2045年的计算机芯片会是什么样?
- 现有设备可能只能支撑先进制程晶圆产出约翻一倍,而非10倍;2030年的供给取决于更广泛的产能扩张。 开场一位未具名的Intel发言人称,AI需求“轻松高出我们最大产能40–50%”。Dwarkesh指出,ASML每年生产的EUV设备不到100台,并称到本世纪末,设备产量大幅提升的计划有限。被问到全球设备是否足以将先进制程晶圆产量提高10倍时,Pushkar Ranade回答:“达不到10倍,但大概能到2倍。”Dwarkesh之后总结的时间表是:现在下单的设备要到2028年到位,新厂房外壳则要到本世纪末前后才能建成;Ranade并未明确确认这一总结。AI算力连续10年每年增长3倍“根本无法持续”,是Dwarkesh的说法。
- AI实验室拿下晶圆厂级产能,是Dwarkesh提出的可能性,并非Ranade的承诺。 Dwarkesh估算,Intel投入数十亿美元资本开支,或可支撑每年约1,000亿美元AI模型收入背后的产能逻辑;他也指出,存储器和产业链其他环节同样重要。他推测AI实验室可能买下产能或保证未来供应。Ranade表示,一些模型公司可能消耗掉整座晶圆厂的硅片产能,也有资金支持这一投入;但这种转变已有“早期迹象”,是Dwarkesh的表述。Dwarkesh建议Intel多买设备时,Ranade最后回应:“如果一年前就知道今天这些情况,我们当时会投得更多。既然现在已经知道,我想我们会增加投资。”
- Ranade认为,Intel在技术上与TSMC只差几个百分点;规模和执行仍是重要短板。 他表示,在性能、功耗或密度上相差几个百分点,“就是吹毛求疵”,更重要的是按时交付,以及良率能否支撑快速爬坡。他反驳了Dwarkesh引用的SemiAnalysis对14A与N2的对标结果。Dwarkesh称,TSMC先进制程晶圆出货量超过Intel的3倍,资本开支约为500亿美元,Intel则约为200亿美元。Ranade表示,晶圆厂成本结构中约80%是固定成本,因此提高产能利用率和良率尤其有价值;他还提到,如今先进制程代工厂只剩3家,而40年前约有20家。
- High-NA EUV是否有价值,取决于芯片架构,而不是单纯比拼设备。 Chris Auth解释,Intel的背面供电放宽了部分正面布线间距要求,因此High-NA对Intel有用;TSMC在没有背面供电的情况下采用更紧密的间距,需要用EUV进行双重图形化。“对他们来说用处不大,对我们来说很有用。”Intel的10nm经历——原定2016年推出,2018年才开始制造——促使公司限制每代制程的创新幅度,并采用阶段门成熟度指标。14A计划从一开始就配备高质量PDK,而18A“起步时没有PDK”。
- Intel退出存储器业务在当下短缺环境中显得代价不小,但Ranade称当时无法预见需求规模;Terafab则是应对需求的另一种方式。 Ranade表示,存储器的供给紧张程度高于算力,同时指出Intel退出DRAM和闪存业务时,没人能预见需求会达到这样的规模。他说Intel正与Elon合作,帮助加快其晶圆厂项目。Dwarkesh指出,设备短缺可能意味着新晶圆厂只是拿到既有供应,并未增加全球净硅片产出;Ranade补充说,晶圆厂还需要电力、水和耗材,并称这些资源比设备更容易扩容。
- 更远期的3D结构是一种可能性,热管理则是限制因素;这不是对2045年的确定预测。 Auth谈到让晶体管在互连结构中悬浮,并探讨未来10年或20年更复杂的3D结构能带来什么。他认为散热是3D器件的限制因素,同时指出系统层面的分析和仿真工具仍处于起步阶段。Dwarkesh另行提醒,技术路线图通常只能看清约4年。
- 混合键合仍有扩展空间,但最密集的未来应用尚属设想。 Tyler Osborn列出互连间距的变化:15年前第一级互连为130–150 µm,如今Foveros大规模量产达到25 µm,研发中的方案已低于10 µm。他提到,今年IEEE ECTC上发表的一篇论文给出了0.45 µm间距器件的可靠性数据。他表示,更细间距的键合未来可能连接芯片之间更低层的互连并降低功耗;达到接近芯片内部互连的水平仍是未来可能性,并非当前量产能力。
- 成本持续上升,正在促使这个风险厌恶的行业提出激进问题。 Ranade表示,晶圆厂成本每4–5年翻一倍,一台High-NA扫描仪加配套设备约需4亿美元。他质疑图形化成本能否继续以这一速度上涨,并问:“如今真的还需要洁净室吗?”他说,没有哪家现有厂商愿意尝试让人进厂吃汉堡、抽雪茄。Kevin Fischer的行事原则是:“如果你非要等一套完整数据,那就已经等太久了。”
1. 推进14A意味着精调2,000道工序,也要吸取10nm的教训
- Chris Auth介绍,14A的开发已超过3年,工艺和设备组合也接近定型。工厂流程大约有2,000道工序,每道都要精细调校,才能稳定地每周重复生产数千片晶圆。缺陷通过线上计量和产线末端电测来发现;TEM截面分析可以定位缺陷所在的层间位置,帮助找出流程中的问题环节。
- Auth回顾10nm时说,Intel设定了激进的“超缩放”目标,并在EUV尚未成熟时,尝试不依赖新设备来实现目标。这个制程最终达到了世界级的良率、性能和成本水平,但所需时间超出预期:原定目标是2016年,直到2018年才开始制造。节目中的新闻片段显示,Intel股价下跌超过15%,TSMC上涨13%。TSMC从2019年起大规模使用EUV;Intel首个EUV制程到2023年才进入产品,因此TSMC使用这些设备的经验约早了4年。
- Intel的制度应对包括针对良率、缺陷和性能设置阶段门成熟度指标,用来判断技术何时能从探索阶段进入开发阶段。Auth的原则是控制每代制程的创新幅度,确保工艺能赶上客户的时间表。
2. High-NA适合Intel,却不适合TSMC——关键在背面供电
- Dwarkesh解释了设备的经济性:High-NA将数值孔径从0.33提高到0.55,单次曝光可打印更小的特征,约为原来的1/1.7。标准EUV设备售价约2亿美元,High-NA设备价格约为其两倍。设备价值取决于能减少多少次图形化步骤;额外步骤既耗时,也会增加缺陷机会。
- Auth表示,Intel和TSMC面对同一设备可能得出不同结论,因为两者的技术架构不同。背面供电放宽了Intel部分正面布线间距要求,因此一些图形可以直接用High-NA打印。TSMC没有背面供电,间距要求更紧,需要采用EUV双重图形化,因此High-NA对其用处较小。在14A中,High-NA是PDK中的一个选项,Intel会与客户逐一讨论是否采用。
- 谈到Intel作为代工厂的学习曲线,节目提到,Intel长期作为IDM经营,并没有正式的PDK流程;18A“起步时没有PDK”。客户反馈已融入工艺开发,14A计划从一开始就提供高质量PDK,并设有0.5、0.9和1.0等成熟度等级。
3. 从“尽量什么都别改”到“抡起大锤拆掉重来”
- Auth对比了80年代和90年代:当时Dennard缩放和光刻推动了可预测的尺寸缩小;而当单靠缩放已不够时,行业进入他所说的“创新黄金时代”。应变硅、高介电常数金属栅、FinFET、全环绕栅和背面供电不断扩充工艺工具箱。他估计,所用材料的数量相比90年代增加了约10倍:“以前是‘尽量什么都别改’(‘try to not change anything’);现在是‘抡起大锤,把东西拆了重来’(‘take the sledgehammer and start tearing the thing up’)。”
- 全环绕栅花了很长时间才进入量产,部分原因是其他方案已经能先满足性能要求。Auth说:“没必要在不得不做之前就去做。”Intel先后采用应变硅、高介电常数金属栅和FinFET,之后才着手全环绕栅。新材料、设备、气体和加热设备可能都需要供应商发明,研发过程也包括反复尝试并淘汰失败的结构。
- 谈及更长期的可能性时,Auth称全环绕栅“多少是不可避免的”,而剥离衬底、将导线放到背面则“有点超前”。他探讨未来芯片能否把晶体管和互连整合进更复杂的3D结构,视野放在10年或20年后。Dwarkesh补充说,技术路线图通常只能看清约4年。
- Auth将算力的限制归为3项:开关频率、每个开关的功耗和散热。对于3D器件,系统层面的热分析和仿真仍处于起步阶段。他说,热管理是一个限制因素,但“这些问题我们可以解决”。
4. Hot Topics会议现场:数据不完整、外延结节与HotBox 1
- Kevin Fischer负责协助决定如何分配工程资源处理18A问题。他说:“你永远不会有一套完整的数据。如果你非要等一套完整数据,那就已经等太久了。”他的工作是判断应该承担多大风险:“现在就上吗?要不要开始冒险投产?”他说,很多工程师看不到自己的工作如何影响Intel的利润和客户。
- 例子是外延结节:异常的外延生长“就像肿瘤”,会迅速扩大,可能导致一层外延与不该连接的另一层短路,使晶体管无法工作。各团队并行尝试不同修复方法,包括用特殊清洗去除结节,以及消除结节的源头;最先看起来有希望的方案未必最终有效。
- 实验批次可以使用分级的“HotBox”系统。优先级最高的HotBox 1会在每台设备上获得优先权,快速穿过整座工厂,但Fischer说这会拖累工厂效率。他打的比方是,为单个实验留出一条共乘车道。
5. 研究实验室:钌、钴的往返,以及CFET的集成难题
- Jack Kavalieros解释了Intel为何在探索钌,用于极细间距互连。铜通常需要衬层来帮助沉积,并与下方的铜连接;衬层可能占据导电路径的相当一部分。钌无需衬层也能刻蚀。Kavalieros表示,在约20纳米间距处,钌的导电性可能优于铜。
- 钴的例子说明材料选择会变。Intel做出决定时,钴是领先方案;但之后出现的新方案让铜重新成为竞争选项。Kavalieros说,随着制造时间窗口临近,每项技术都会与替代方案重新比较。
- CFET研究使用短流程试验载体,获得结果的速度比完整制造流程快;后者需要1个月或更久。团队可以从二极管、电容器等组件入手,再逐步组合成晶体管。简化版CFET可能只用1根线连接NMOS、另1根线连接PMOS,而不是将4条纳米带叠在另外4条纳米带上。难点包括垂直互连、高深宽比刻蚀,以及在微小空间内填充材料且不留下气隙。
- Dwarkesh问,为什么实验室版本并不意味着CFET已能用于手机,并在问题中提到10年这一时间尺度。回答并未给出明确量产时间:实验室版本经过简化,性能未必优于并排排列的纳米带。技术还要经过许多步骤,包括选用合适的金属和介电材料。材料可能因为接触不牢,或后续工艺与未密封的薄膜发生相互作用而失效。
6. 混合键合正在模糊封装与芯片之间的界线
- Tyler Osborn对比了晶圆对晶圆键合和芯片对晶圆键合:前者常用于CMOS图像传感器,但要求晶粒高度匹配,且需要对应的筛选图;良品和坏品随机分布可能拉低良率。芯片对晶圆键合则可以先测试并挑出已知良品,再将其键合到已知良好的位置。Osborn预计两种方式都会继续使用,并称芯片对晶圆键合适合逻辑芯片之间的连接。
- 互连间距的变化是:15年前第一级互连为130–150 µm,如今Foveros大规模量产达到25 µm,研发中的方案已低于10 µm。Osborn提到,今年IEEE ECTC的一篇论文公布了0.45 µm间距混合键合器件的可靠性数据;这并非当前大规模量产水平。他认为间距还有进一步缩小的空间。
- Osborn表示,如果封装间距能做到约0.5 µm或更小,就可能连接芯片之间更低层的互连,从而降低总IR压降。对于包括客户端设备在内的非AI用途,他强调互连密度和更低的每比特功耗,这意味着在电气性能相同的情况下可以减少发热。
7. 供给上限:有望翻倍,但做不到10倍
- 节目开头,一位未具名的Intel发言人称,AI需求“轻松高出我们最大产能40–50%,我以前从没见过这种情况”。之后Dwarkesh指出,ASML每年生产的EUV设备不到100台,并称预计到本世纪末产量也不会显著增加。Ranade认为EUV是瓶颈之一,但设备短缺不止于EUV:一旦18A等制程被锁定到特定设备,Intel就不能简单换成另一家供应商的设备。
- 被问到全球设备是否足以将先进制程晶圆产量提高10倍时,Ranade回答:“达不到10倍,但大概能到2倍”(“Not 10X, but probably 2X, yes”)。Dwarkesh据此称,如果供应链及其下级供应商不扩大产出,AI行业算力每年增长3倍“根本无法持续”;这是Dwarkesh的判断。
- Dwarkesh之后给出一份时间表总结:边际产出可能在约12个月内上升,但到2030年,产量可能不会比当前预测高多少;设备交期为18个月,现在下的订单要到2028年到位,新厂房外壳则要到本世纪末前后才能建成。节目中没有Ranade明确确认这一总结。谈到14A时,Ranade说Intel会尽量保留不同制程间设备的通用性;18A的设备组合中或许有约80%可以复用。
8. 数十亿美元资本开支、1,000亿美元AI收入:一种购买产能的设想
- Dwarkesh估算,Intel投入约20亿美元资本开支,或可支撑每年约1,000亿美元AI模型收入背后的产能逻辑;他同时指出,存储器和产业链其他参与者也很重要。他推测AI实验室可能买下所有产能,或保证未来供应。Ranade表示,一些模型公司的需求足以消耗整座晶圆厂的硅片产能,也有资金来支持这一投入;节目中所谓这一转变已有“早期迹象”,是Dwarkesh的说法,不是Ranade的判断。
- 谈到Terafab时,Ranade说,Elon意识到自己的业务需要大量硅片,Intel认为自己可以帮助加快晶圆厂项目的启动。Dwarkesh指出,设备瓶颈可能意味着新晶圆厂拿到的是有保障的供应,却没有增加全球净硅片产出。Ranade补充说,晶圆厂还需要电力、水和耗材,并称这些资源比设备更容易扩容。
- Dwarkesh建议Intel承诺多买设备,据称Nvidia已在存储器和其他组件上这么做。Ranade回应:“如果一年前就知道今天这些情况,我们当时会投得更多。既然现在已经知道,我想我们会增加投资。”
9. 追赶TSMC不只看晶体管密度,规模和存储器供应同样受限
- Ranade表示,性能、功耗或面积相差几个百分点,“就是吹毛求疵”;更重要的是按时交付,以及良率能否支撑快速爬坡。他说,一项技术不只包括一种晶体管,还包括低漏电和高性能晶体管、SRAM、模拟电路和RF。他反驳了Dwarkesh引用的14A对比N2基准测试,但节目中没有给出另一组密度数据。Dwarkesh称,TSMC先进制程晶圆出货量超过Intel的3倍,资本开支约为500亿美元,Intel则约为200亿美元;Ranade认为这一比较有些不公平,因为TSMC为许多客户提供代工,而Intel的代工业务主要服务自身。
- Ranade表示,晶圆厂成本结构中约80%是固定成本,因此在同样的厂房规模下,提高利用率、产出和良率可以大幅改善经济效益。他说,先进制程代工厂如今只剩3家,而40年前约有20家。谈到Intel退出DRAM和闪存业务,他说当时有充分理由,也没人能预见需求会如此庞大;如今存储器的供给紧张程度高于算力。
- Ranade表示,晶圆厂成本每4–5年翻一倍,一台High-NA扫描仪加配套设备约需4亿美元。他质疑图形化成本能否继续以这一速度上涨,并提出从零开始审视行业惯例的问题,例如:“如今真的还需要洁净室吗?”他说,没有哪家现有厂商愿意真的在厂房里做吃汉堡、抽雪茄的实验。他还补充,一些CPU设计实践可能也被锁定在30年前形成的路径上。
完整逐字稿
There’s never been as big a shock to the semiconductor industry as the current surge in demand from AI.
AI is driving incredible computing demand—easily 40–50% above our maximum capacity, which I’ve never seen before.
Progress in AI has been driven by exponentially increasing compute. To sustain that progress, foundries like Intel will need to manufacture far more leading-edge compute, both by producing more chips and by improving what each chip can do. But the production of these chips is bottlenecked by tools Intel buys from its suppliers. The most famous are ASML’s EUV machines.
If they don’t have the equipment, they can’t make the chips here.
1. How Intel brings up a new process node
I spent 2 days touring Intel’s fabs to prepare for these interviews with its leadership. I wanted to understand what it takes to manufacture the world’s most advanced chips and how hardware is shaping the future of AI. I’m joined by Chris Auth, who leads development of all the processes that are currently in manufacturing.
The thing I want to understand in more concrete detail is how the development of a new process actually happens. If 14A is going to come out 2 or 3 years from now, what is happening from now until then? Walk me through as much detail as you can, from how the yield is improving to what kind of telemetry you look at and what kind of experiments you run. I want to understand as concretely as possible what’s going to happen over the next 2 years.
14A has been in development for about 3-plus years at this stage, so quite a bit of pre-work has been done to get it to where it is right now. We’re getting very close to finalizing the process. We’re finalizing the tool sets it will be manufactured on, and we’re fine-tuning each of the process steps.
There are about 2,000 steps in the factory that you have to do. You need to do really intricate work at each one to make sure it’s fine-tuned, can go into manufacturing, can run thousands of wafers a week on this process, and can be repeated every single time.
Right now, you might have a certain yield. Walk me through how that increases month over month. There’s a line running at 14A. What happens from now until next month that will result in the yield changing? How do you identify where the defects are? How do you fix that?
There’s a constant process that we go through to identify defects. There are 2 main ways we identify them. One is through inline metrology. We have tools that look at the wafers and say, “Ah, there’s a defect there, there’s a defect there, there’s a defect there.”
Then, at the end of the line, through electrical testing or sorting, we see where the failures are. We identify failures, and then we get an analysis of those failures. We cross-section them. You were in the TEM lab yesterday, and you saw how you can get cross-sections.
You get a cross-section of a defect, and from that, you can say, “Oh, that defect is between these layers, so it must have come from this section of the flow. Oh, we have inline metrology in that section, which has identified defects. Those are the defects we need to go after.”
What we’ve learned is that you don’t want to do too much innovation in one node, because the more innovation you do, the more complex it becomes. You’ll be able to get it to work, but you need to hit a certain schedule, and that’s the schedule your customer ultimately wants. Having a predictable schedule is a key piece.
You’ve got to figure out how much innovation you can put in to meet the customer’s requirements within the timeline they need.
2. What Intel learned from 10nm
Intel learned how costly that tradeoff can be with delays to its 10-nanometer node, whose original target launch date was 2016 but which didn’t begin manufacturing until 2018. Usually, Intel has been the keeper of Moore’s Law, with a new manufacturing cadence every 2 years, but its last set of products slipped almost 4 years.
Intel today is having its worst day in 4 months, the stock now down more than 15%. I also want to point out Taiwan Semiconductor, up 13% off of Intel’s bad news.
Walk me through what lessons you think Intel has learned from 10 nanometers.
10 nanometers was a good example of where we had very aggressive targets. We were doing what was called hyperscaling at the time, so we were scaling much faster than what had historically been done. To do that, we came up with all sorts of innovative ideas about how we could achieve it without new tools, because the tools weren’t ready.
10 nanometers is a great technology. It has world-class yield, world-class performance, and world-class cost, but it took us longer to do than we would have liked. So we’ve tried to take that learning into future technology nodes and say, “Hey, we need to limit the amount of innovation we put in there to make sure that we keep it on schedule.”
What do you think was the main technology that should’ve been saved for a future version?
EUV was probably the big thing. When we started to define 10 nanometers, the conclusion was that EUV was not ready.
EUV is extreme ultraviolet lithography. It prints chip patterns with light at a wavelength of 13.5 nanometers, about 14 times shorter than that emitted by previous tools chipmakers had relied on. The shorter the wavelength, the finer the features that a single exposure can print. But Intel decided this technology wasn’t going to be ready in time.
TSMC transitioned to EUV much sooner. It put EUV into volume manufacturing in 2019 and ramped it up further on its 5-nanometer node in 2020. Intel’s first EUV process did not reach products until 2023, so TSMC had about 4 more years of experience with these machines.
Yesterday, we were at the research lab getting a preview of 2D materials, CFET, and ruthenium interconnects. I’m curious about how you decide whether that technology is mature enough for the next node.
One thing that did come out of 10 nanometers is that we started to define a set of maturity metrics. We use those metrics in a process we call phase gate, where we would say, “To go from pathfinding into development, these are the criteria that we need to hit.”
There are yield criteria, defect criteria, and performance criteria, and we need to hit those in order to move to the next set of the flow. If there’s something that doesn’t meet those criteria, it goes on to the next technology. We focus on the items that are ready and that we can run and put into a process, because one of the key things is staying on schedule.
3. From planar transistors to gate-all-around
Staying on schedule is hard partly because new transistor designs take decades to mature. Modern chip transistors evolved from the planar MOS transistor, demonstrated in 1960. The history of transistors since then has been a progression from 2 dimensions into 3. Each development Chris goes on to describe, from FinFET to gate-all-around, is a step in that progression.
So it’ll help to first look at a basic transistor and how its parts have changed over time. A transistor is basically a switch. When it’s turned on, it allows current to flow between its 2 ends, which are called the source and the drain. A piece called a gate sits on top of the silicon between the source and the drain.
Applying a positive voltage to the gate turns the switch on, because the positive voltage pulls negatively charged electrons in the silicon beneath up toward the gate. However, a thin layer of insulation stops them from actually reaching the gate. So the electrons collect just beneath that insulation and form a thin conducting path from the source to the drain. This is called the channel.
Remove the voltage and the electrons disperse, the channel disappears, and the switch turns off. As transistors shrank, the source and the drain got so close together that current could flow through the channel even when the switch was supposed to be off. We needed a better way to control the channel and prevent current from leaking through.
The fix was to give the gate a tighter grip on the channel by touching it from more sides. In the original planar transistor, the gate only touches the channel from the top. The FinFET transistor squeezes the channel into a thin vertical fin of silicon. The gate drapes over the fin, so it controls the channel from 3 sides.
The next progression from there was to cover not only the top and the sides of the channel, but also the bottom.
This technology is called gate-all-around. It slices the channel into thin ribbons, each of which gets completely wrapped around by the gate. But getting gate-all-around to work required new materials and new manufacturing steps.
To build these floating ribbons of silicon, you first sandwich them between alternating layers of a temporary placeholder material, which holds the space where the gate will eventually go. We use a placeholder because the materials in the real gate wouldn’t survive the processing that comes after, which involves baking the wafer at around 1,000 degrees Celsius.
Once these hot steps are done, chipmakers etch away the placeholder, leaving the ribbons suspended. Then they fill the gaps around every ribbon with a thin coat of a special insulator called a high-k material, whose purpose is to let the gate pull more strongly on the channel. On top of this material, they put the metal of the gate itself.
FinFET was demonstrated in a lab in 1989 and reached volume production at Intel in 2011. A gate-all-around transistor had been demonstrated a year earlier, in 1988, but Samsung didn’t begin producing gate-all-around chips until 2022. So these ideas, FinFET and gate-all-around, were developed around the same time, but they reached production a decade apart.
I wanted to ask Chris why it took so long to get to this current gate-all-around technology. Maybe you can walk me through the process of getting into high-volume manufacturing. I want to understand concretely: once you have an idea that, “Hey, we’re going to make the channel smaller, we’re going to surround it,” how do all the other problems of material science get figured out? How do you figure out how not to destroy the gate? Why does it take so long?
Gate-all-around’s a good example, because back in the ’90s, we knew of this idea. But we knew there were going to be these problems with how you put this into high-volume manufacturing. At the same time, there are other things, like high-k metal gate. There’s strained silicon, and there are FinFETs that are out there.
It’s a question of when the right time is to tackle those. Well, you don’t want to tackle something before you have to. If you have these other things that can drive performance, you would go and do that. So we went through this path. We did strained silicon, high-k metal gate, and FinFETs, and then it became, “Well, we need to do things further. How do we get there?”
Gate-all-around’s really the ultimate transistor out there. Maybe it’s time to start tackling some of those issues that you have. You’re right: now you have to look at how you put high-k metal gate in with gate-all-around. It’s that innovation that takes time.
Sometimes you need new materials. Sometimes you need a different tool to be able to do some of the things that you need to do, and that requires invention from the tool vendors. You have to go to the tool vendor and say, “Hey, I need a tool that can do XYZ. I need a gas that can deposit this particular material that goes into that. I need a heating chuck that has this characteristic to it.”
All those things take time. Some of it’s iterative, where you have to run a gate-all-around transistor and say, “Oh, well, that didn’t work. Let me figure out what was wrong with my hypothesis and try it again with some different structure.”
How has the nature of R&D changed from the era of just making planar transistors smaller and smaller and getting the benefits of Dennard scaling to the world we’re in today? Is it just a totally different kind of R&D process?
Previously, it was, “Let’s make things smaller, smaller, smaller.” Now you look at all these other facets of performance at the same time, and improvements in size don’t come as easily. Walk me through whether there was some crucial change in the R&D process at that point.
If you look at the ’80s and ’90s, yes, it was driven really by Dennard scaling and lithography. We just made things smaller; transistors got faster, they got more reliable, and it was a very predictable cadence. When we started to hit the 2000s, we saw, “That’s not good enough anymore. We need to do something different.”
To me, it became this golden age of innovation. For each technology node, how are you going to provide more scaling? How are you going to provide more performance? It drove things like strained silicon. It drove high-k metal gate. It drove FinFETs, gate-all-around, and backside power.
These are things that in the ’80s and ’90s you would be like, “Oh no, we’re not touching any of that,” because we just continued to have the same process flow. We just scaled it, scaled it, scaled it. But for somebody like me who’s a transistor junkie, it’s awesome, because now the playbook’s open. You can do all sorts of things out there.
You can bring in new materials. Just look at the number of materials we used to use in the ’90s versus the materials today. It’s probably gone up 10X. There’s a lot of innovation. There’s atomic layer deposition. You’re controlling this stuff atom by atom.
So it’s changed a lot how you approach the process. Before, it was, “Try to not change anything.” Now it’s, “Take the sledgehammer and start tearing the thing up and come up with some new idea.”
4. Why High-NA EUV pays off for Intel but not TSMC
For 14A, Intel is using a new kind of lithography machine: High-NA EUV. It uses the same extreme ultraviolet light as today’s EUV machines, but changes the optics. NA, or numerical aperture, is a measure of how wide a cone of light the machine’s mirrors can focus onto the wafer. The wider the cone you can focus, the smaller the spot that your light can carve.
Standard EUV machines have an NA of 0.33. High-NA widens it to 0.55, so High-NA can print features about 1.7 times smaller in a single pass. When features are smaller than the lithography machine can print, chipmakers have to split the pattern across several passes, each printing a different set of features. The most tightly packed patterns can require 2, 3, or even 4 passes.
Each additional pass takes up valuable time on a machine that costs around $200 million, and it introduces another opportunity for defects. High-NA machines cost about twice as much, but they can reduce the number of passes that are needed. So the question that determines whether they justify their higher price is how much more time they save and how much they reduce the risk of defects.
Now you guys are using High-NA EUV tools for 14A, whereas TSMC has said that they don’t make economic sense yet for them. How do you decide whether the next litho tool is the one that’s ready to adopt or not?
High-NA’s a good example of where, because of the architecture of our technology versus TSMC’s, we make different conclusions off of the same tool set. We use backside power. That means that you actually alleviate some of the pitch requirements you have on the front side. That allows you to print that directly with High-NA.
TSMC has to run tighter pitches because they don’t have backside power, and they can’t do that with High-NA, so they have to use double patterning EUV. So for them, it’s not very helpful. For us, it is very helpful.
Now at 14A, we’ve left it as an option, and it’s something that we’ll have a discussion with the customer on, because there’s some value proposition to it, and there’s some complexity that it adds.
Chris is referring to a feature called backside power. A chip has two different kinds of wiring. Power lines deliver electricity to the transistors, and they need to be thick. Signal lines let the transistors talk to each other. They’re much thinner, but they need to be spaced apart so that the signal from one wire doesn’t interfere with the signal from another.
In the past, all of these power lines and signal lines had to be crammed together on top of the transistors. Intel’s newest process moves these power lines below the transistors, to the back of the wafer. This frees up space on top, so the signal lines don’t have to be packed as tightly.
This change makes High-NA worth it for Intel. Without backside power, the wiring is so tight that it would require multiple passes to print, even with High-NA. With backside power, a single High-NA pass is enough.
Outside companies can now commission Intel to manufacture chips that they’ve designed. They follow Intel’s process design kit, or PDK: the menu of what a given process can build, and the rules for building it.
Do you need to lock that into your PDK right now for customers who are planning on developing on 14A?
It’s an option in the PDK today, and we’re handling it as a customer-by-customer discussion as to whether or not they want to go down that path.
For 18A, there was public reporting that there were delays in or issues with the PDK, such that some instructions didn’t work, and it was difficult for people to use your foundry to build their chips.
Tell me about the process of Intel becoming a foundry and then having a PDK that other customers can use to make whatever chip they’re making as well.
There’s definitely a learning curve to how you become a foundry. That’s something our competitors have gone through as well. PDK is a good example of that.
For decades, we’ve been an IDM. We’ve gone to our product teams and shown them our transistor data, and we share that data back and forth. We haven’t had a formal PDK-type process, so that’s a new process we’ve had to implement on 18A. 18A started out not having a PDK.
There’s definitely a lot of feedback we’ve gotten from customers about what they expect for the quality and maturity of the PDK and what sort of information they want to see in there. We’ve tried to incorporate that into making sure we have a PDK that meets our customers’ requirements. That’s where we’ve ended up.
We’re starting to get PDKs that have this, and 14A will have that from the get-go. It has very high-quality PDKs. Again, there are maturity metrics for what is a PDK 0.5 versus a 0.9 versus a 1.0. We’re constantly going through and taking customer feedback and incorporating that into the quality of our PDK.
For most of its history, Intel’s fabs made only Intel’s chips. That could be part of what allowed TSMC to gain an edge. Serving many customers gave TSMC more wafers to learn from, more revenue to reinvest, and more pressure to hit deadlines.
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5. Could chips have evolved completely differently?
If a butterfly flapped its wings in the ’60s, could you imagine a world where gate-all-around isn’t even a word people have heard of or an idea people are familiar with, and people are thinking of an extremely different branch of the tech tree? How far down the tech tree do you think things could be totally different? Could it be that we’re not even using copper?
If you look at, say, transistors and interconnects, where we’ve gotten to—as far as the transistor and gate-all-around being the ideal transistor structure—was somewhat inevitable. As I said, in the ’90s we were already talking about these types of things.
Backside power, that one’s pretty out there. Even in the ’90s, the idea that you’re going to strip off the entire silicon substrate and put lines on the backside is probably something that’s a little bit out there.
Copper, of course—copper wires are the best, so I don’t know how you would end up somewhere else besides copper. But you guys are exploring other—
For some of the very tightest pitches, it’s inevitable that you will replace copper. That’s a good example of where you will have another material that will come in there. But for the larger lines, I think copper is about where it’s at.
Once you start to do gate-all-around transistors and you do backside power, you start to enter a very different regime. Now you see it’s not, “Hey, there’s just some substrate and you stack everything on top.” Now you’ve got a transistor that’s floating in interconnect, and you’re like, “Okay, well, why don’t I have transistors, interconnect, a little more transistors, more interconnect?”
This whole 3D stacking that we now do with just discrete chips that we stack on top of each other—you’re like, “Why can’t I just build an entire structure like this?” You see it with memory, NAND, DRAM. NAND already does it, DRAM talks about it, but I think DRAM inevitably is going to go there too.
A lot of people say, “Oh no, we’re not going to do this because we can’t do it in the next five years.” Well, come on, let’s put a larger timescale on this. Let’s put 10 years, 20 years. In 2045, do you think you could do it? Now you start to say, “Oh yeah, I could see us having some pretty exotic structures at that point.”
We limit ourselves by what we see as possible in the next four years. As I’ve always said, when people ask, “How do you see technology scaling going?” we have visibility for about four years. Then you get out to the four years, and you go, “Yeah, I think there’s something we can do another four years out of that.” And you get to that four years, and you’re like, “Yeah, I think you can do something.” But if you start to talk about 10 years, it becomes hard to say what it’s going to be.
Chris’s idea of building upward could start with the transistors themselves. Chips use two types of transistor, called n-type and p-type, which work the same way, but with the charges reversed. Nearly every circuit is built by pairing them up.
Today, chipmakers build them side by side. The next step is to stack them directly on top of each other to save space. In principle, that fits twice as many transistors into the same area. This design is called a CFET, short for complementary field-effect transistor.
But every extra layer adds manufacturing steps and cost, and also leads to heat building up that doesn’t have a clear way to escape. Because logic consumes more power than memory, you can’t do stacks of DRAM that make HBM or 3D NAND as easily with logic, because of the heat issue. Is that the fundamental issue over the long run? How you—
Thermals. There are 3 things you have when you try to say, “Hey, what limits compute?” It’s how fast you can do the switch, so the frequency of the device. How much power does it take to do that switch, so the power efficiency of it? The third one is, how do you dissipate the heat that was generated by doing that switch? That’s the thermals piece of it.
These are not new problems. You can go back 20 years and see articles on these 3 things. The question is, thermals—how do you deal with that, particularly when you start to talk about these 3D-type devices?
There is a need for that sort of system-level analysis and simulation tools. I think we’re in its infancy because we’ve just started to look at this. It is a limiter, and it will be a limiter, but again, these are problems that we can go solve.
6. Inside Intel's "Hot Topics" meeting
The problems respond to work, but engineering time is finite, and so are the wafers for experiments. Deciding where they go across thousands of problems is itself one of the hardest parts of bringing up a node.
I sat in on one of Intel’s Hot Topics meetings, where those decisions get made. I’m here with Kevin Fischer, who was laying down the law this morning at the Hot Topics meeting, where you guys were discussing how you’re improving 18A and 18A-P technologies. People would come to you with different experiments they were running, different ideas they had for improving yield and performance, and then you and your integration engineers would tell them what data you needed, how they should proceed, how you think they could move things faster.
I want people to have a sense of the culture at these meetings. One thing I found striking is that this is bottlenecking your most advanced node. You want progress to happen fast, so you lay down the hammer.
I would say the average engineer doesn’t understand the stakes or the urgency of how this is going to impact Intel’s bottom line, how it’s going to impact our customer. They just have no visibility into those issues. They will typically have a certain set of criteria that they want to go capture.
They’ll hit boundaries of, “I asked for something and someone said no, and I’m done. I guess I can’t have this thing that I asked for.” One thing you learn in this industry is that you will never have a complete data set.
If you want to wait for a complete data set, you’ve waited too long. It’s already too late. A lot of what I end up doing in those meetings is deciding how much risk we’re going to take on a certain decision, or not take on a certain decision. You need to say, “Look, do we go now? Do we start risking production?” Because you’re risking the bottom line. You’re risking revenue. I’m worried you’re going to put me in the light of being an ogre because I’m putting the hammer down on people.
That’s a great reputation to have. It’s really conveying urgency. Every day counts. Can you walk me through a particular issue that might come up?
One of the examples you saw this morning is epi nodules.
Epi is short for epitaxy, which means growing new material on top of an existing one. Chipmakers flow gases over a heated wafer, and the gases leave atoms on its surface. The crystal structure of the material underneath acts as a template. Each new atom lines up with the atoms below it, and the new layer continues the same crystal. Chipmakers use epitaxy at several stages of making a chip. In the step Kevin describes, they use it to grow the source and the drain as small crystals on either side of the gate.
During the deposition of our epitaxy, we get abnormal growth, a little thing like a tumor. It’s growing super fast. That causes problems, because one epi will short to the wrong epi and you get transistors not working. Then you’ve got to narrow it down to how you’re going to fix it.
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One of the pieces that you observed this morning was a special clean that we were looking at, which would eliminate the nodule. The nodule would deposit, and then we’d get rid of it. Some of the other discussion was about the source of the nodule—getting rid of the source of the nodule. There’s some issue. How do you decide what the source of it is?
For the most part, we work highly parallel.
How do you decide?
It’s not always evident what the easiest way to fix the problem is, so you work on all the potential fixes. Sometimes it’s not the one you expect first. Once we’ve identified it as a primary problem for the technology, that’s where this Hot Topics meeting gets involved. That’s how we align the resources into those engineering teams so that we can accelerate the work.
You said that there’s some fast-track process where wafers can move through faster if they’re bottlenecking some experiment.
We have a tiered system of what we call hot boxes in the factory. Every grade of hot box goes a little bit faster. It’s just how the factory prioritizes that particular lot, that block of silicon that’s running through the factory. Our highest grade of hot box, HotBox 1, races through the factory. It gets priority at every single tool, but it’s a drag on the entire factory. If you had a factory person in here, they don’t like playing that card, because you end up using the tools inefficiently so that you can go super fast.
Think of it as a highway, and you set aside that one lane for the carpool, which everyone could use, but you’re saying, “Okay, it’s just the carpool.” That’s our HotBox 1. Everyone clear out of that lane except for that one experiment, and that one experiment races down the highway.
7. Replacing copper wires with ruthenium
Kevin’s job is deciding what goes onto the production line now, but the day before, I went to Intel’s research lab with Jack Kavalieros to see ideas that aren’t ready for the node yet. We started with wiring. A transistor is only useful once it’s connected to others, and on a modern chip that takes more than a dozen layers of metal wire stacked above the transistors, called interconnect. Those wires are made of copper, and as they shrink, copper starts to run into trouble. Intel is exploring a replacement: ruthenium.
Ruthenium has higher resistivity, so why are you guys exploring ruthenium for the future?
Interestingly enough, as you scale the dimensions of those copper wires, you run into challenges. For example, copper typically requires a liner in order to deposit the copper to fill those lines. Ruthenium is very different in that regard because it’s a material that we can actually etch. As such, by etching it, we don’t need that liner. Now you scale those very fine dimensions, and if you can trade off that resistive liner with no liner, ruthenium starts to win. There is a crossover point where ruthenium will have much better conductivity, better resistivity than copper. That’s roughly in the 20-nanometer pitch range, which means, if you can imagine, half of the pitch is your metal line, and the other half is the dielectric that isolates them.
So what is the liner?
Think of it almost like a glue layer or transition layer that we need in order to deposit the copper and have it stick, and have it make that connection to the copper lines below it. These are all interlocking copper lines that interconnect to each other. But every time you deposit copper, you’ve always had a liner underneath it. In the past, that liner may have been a significant portion of the entirety of that conduction path. But over time, we’ve scaled it, made it thinner, and so copper comes back into play as a contender.
One thing I’d be curious to know is how you decide that a technology is mature and ready for high-volume manufacturing. With 10 nanometer, you were mentioning you guys moved on from copper to cobalt, and there were potential issues with that. How do you decide that this technology is going to work at scale?
The integration of these materials into such a complex system as the transistor ecosystem involves many, many different components. The scalability is one part, but its ability to integrate is another. At the time we made a decision for cobalt, it was the forerunner. The results were stronger at the time. But as we work with our ecosystem externally, the vendor ecosystem that provides these materials and the tools that we integrate them with, we find solutions down the road that may bring copper back in line as being the stronger of the two. That’s exactly what happens.
Every technology that we go through, we will evaluate multiple options. As we get closer to our time horizon for delivering a manufacturing-worthy product, we have to make a decision. The leading option at the time was cobalt. Now it’s copper again, and perhaps in the future it’ll be ruthenium.
8. Why stacked transistors take a decade to ship
I’d love to get your thoughts on CFET, basically stacking the transistors on top of each other. What is progress like there? Can you keep making more and more layers? Is it just two? Can you go three, four? How high can you get?
That evaluation of CFET is currently underway. Not just by us, by our competition. Labs externally are looking at it. It is the ultimate in stackability. We’re taking transistors that had to be compressed more and more, and we’re relaxing that in some ways because we’re going to stack them on top of each other. But the act of stacking does not mean that they’re not interconnected. What used to be connections on the top or even on the bottom, as we’ve seen from our press release, now has to go vertically in between the transistors. That’s a new challenge because the aspect ratio of creating trenches and filling those trenches becomes more and more difficult. It’s not as straightforward as stacking the transistors, because you still have to think about interconnecting them.
Is the issue there the etch to get that deep hole?
Aspect ratio for the etches is a big part of it. We’re working with our vendors to evolve on that and to improve that, but it’s also what you fill those very tiny spaces with.
Because filling can sometimes leave air gaps or holes that are never really filled, and that’s not ideal.
I assume there’s a version of CFET that works inside this lab. What is the kind of wafer or process that’s working right now? Then what’s the next step? What’s the next step after that, until it’s inside the full high-volume process?
Part of the process of evolving these technologies, especially something more complex like an architecture—not just a basic chemistry or a material, but a full architecture like CFET—is that we have to make short-loop vehicles that can give us faster turnaround. The normal manufacturing process can take a month or longer to complete the thousands of steps that it goes through.
Our goal here is to take unit cells of that process and qualify them. We take advantage of short-loop vehicles that can give us electrical parameters, chemical parameters that can resolve some of those challenges, those speed bumps. Once we’ve resolved them, then we combine them into a more complex test vehicle.
What you would find in here is something very simple. You might be making a diode, you might be making a capacitor, which are components of the transistor. As those evolve and become stronger, better performing, you combine them to make the next stage, which might be the transistor itself.
In the CFET example, you might not choose to do four ribbons on top of four ribbons. You might just choose to do one on one, because naturally the aspect ratio of dealing with something that much taller becomes more and more challenging. So we would have a simplified version of a CFET, which has only one wire for the NMOS and one wire for the PMOS. That simplifies our job, but it still helps us evaluate the stacking of devices and how they will interconnect.
But are the feature sizes here as small as they will be eventually? Or are the feature sizes bigger?
Oh, absolutely. In some cases, at least as small. For example, you’ve heard of 2D materials, these transition layer dichalcogenides, as they’re called. They’re very, very thin materials. They’re essentially one monolayer of atoms that we deal with.
Those depositions can happen in this lab. We can evaluate those films in terms of conductivity, our ability to contact them, our ability to modulate that conductivity, which is what the transistor does. So yes, we do have the ability to not only deposit films that are very small and thin to the atomic scale, but also print very small features. We have EUV technology, or e-beam technology, that can allow us to print very small features similar to what we will eventually make in production.
I guess I don’t understand intuitively, lacking the context in this process, if you have features that are as small for a working CFET right now, why will it take 10 years for it to be in my phone? I understand that there’s a process, but why is it such a long process?
The answer is slightly different when you’re dealing with an architecture like CFET versus a novel material. Materials have, of course, the challenges of being deposited, etched, and removed. Their compatibility with other layers above and below—all those things have to be researched first before you put them in a production line.
An architecture may seem like a simple evolution. “Oh, you’re making nanoribbon transistors next to each other. What’s wrong with just stacking them?” But the act of stacking them, of course, increases the aspect ratio for etches, depositions, and cleans, and the technology may simply not be ready yet.
But if you’ve already made it here, there’s a version of the technology that’s ready, right?
Correct. We’ve made a simplified version that may not be an advantage over our current side-by-side technology of nanoribbons, but we need to evolve it to make it maybe two nanoribbons, or to add the right type of metals and dielectrics, in order to extract the maximum performance out of that device.
Got it. So it’s like a long tail of—
There’s a thousand different steps that all have to come together in a very unique way to make the performance compatible or actually supersede the prior technology.
Where do the ideas tend to fail? You have 20 ideas like 2D materials. What is the way in which you decide this is actually not worth pursuing further?
Sometimes we discover fundamentals about the material that will be incompatible with the rest of the processing that we do. The first level of experiments may simply be very simple depositions. You say, “Okay, I can deposit the film, I can look at it, I can measure it. But the moment I try to make a contact to it, nothing sticks.”
It could be something as fundamental as the adhesion. The next step in the process simply has no way to adhere to the material. So you may rule out a material because of something as simple as that.
More complex challenges might be that the subsequent processing may have gaseous interactions with downstream steps. For example, I’ve deposited the film, I’ve capped it with other materials, but they’re not hermetic. So my third or fourth or fifth step in the process may actually still interact with it and change its properties.
That makes it unstable, and now we have to find better hermetic sealing for that process. If we don’t find a way to control it, then it’s a dead end for us.
9. Hybrid bonding and the chip-to-chip bottleneck
Stacking transistors is still in the research lab. Stacking whole chips is already in production, and it tackles a different problem: how separate chips communicate with each other. Modern computers are divided into multiple parts, each optimized for a different task.
For example, Nvidia’s Blackwell data-center GPU joins two huge processor chips and surrounds them with eight stacks of high-bandwidth memory. These chips have to constantly send data back and forth with each other. And in AI, the speed of that traffic, not the raw computation itself, is often what limits how fast the workload finishes.
Imagine two chips side by side, communicating through their facing edges. If you double each chip’s width and length, you’ll have four times the area for circuitry, but only twice the edge length for connections. This is the area-versus-perimeter problem.
As transistors become denser, a chip’s ability to do computations increases faster than its ability to move data around. The industry has known about this problem for years, so multiple technologies have been invented to address it.
The completed circuits must undergo two last operations: bonding and packaging. Once a chip is made, it still has to be connected to other chips and to the rest of the computer. That step is called packaging, and it has changed a lot in the last few decades.
At a high level, you can think of the evolution of packaging like this: initially, chips were laid out side by side. Wires connecting them went out the side of one chip to another. To allow for more communication density, the industry introduced a shared piece of silicon, called an interposer, for multiple chips to sit on.
A chip can talk to other chips through the wiring that runs directly through the interposer. This type of packaging is often called “2.5D.” Another way to increase connection density is to bond chips directly to one another. This allows for shorter connections between chips, but the early versions of this idea used solder bumps, which are bulky and increased resistance.
It would be better to skip the solder and fuse the signal wire connections of the two chips directly to each other. This is called hybrid bonding, and it is one of the technologies the semiconductor industry is investing in the most.
Hybrid bonding works by aligning the copper interconnects of one chip with those of another. Then these chips are pushed together and heated so their interconnects expand and bridge the gap between the chips. This process makes the insulating surfaces around the copper bond as well. And so, by removing the solder bumps, you end up with much denser connections.
But the reason this technology is only now entering volume manufacturing is because it took a while to iron out the alignment and defect challenges that it introduced. In the packaging lab, I asked Tyler Osborn, a director in Intel’s advanced packaging technology development group, how they put this into practice.
Intel has spent over 50 years optimizing its CPUs for speed. But lots of these optimizations—like caching and branch prediction and speculative execution—reduce predictability. The exact same instructions can take four cycles to execute one time and 300 the next. When you stack billions of instructions together and execute them across multiple threads and cores, these non-determinisms compound into all sorts of hard-to-reproduce bugs. If you work on serious systems, you’ve definitely experienced this. Antithesis solved this by doing something a bit crazy: they built a 100% deterministic computer. They identified every single door in Intel’s x86 architecture where non-determinism could leak in—network packets, disk reads, temperature sensors, even time itself. And they either welded each of these shut or slotted in a controlled simulation. This deterministic computer is just a foundation. On top of it, Antithesis built a testing platform that compresses years of production hardening into minutes. It runs your software through thousands of parallel worlds, injecting faults and intelligently steering each one towards a one-in-a-billion failure that you’d never be able to test yourself. This determinism is what’s behind all the other insane Antithesis features that I’ve mentioned over the past few episodes. It’s what lets you reproduce any bug and time travel to any point in the test run. Most importantly, it’s what lets you—or your agents—trace every failure back to its root cause. Go to antithesis.com/dwarkesh to learn more.
Intel has spent over 50 years optimizing its CPUs for speed. But lots of these optimizations—like caching, branch prediction, and speculative execution—reduce predictability. The exact same instructions can take four cycles to execute one time and 300 the next.
When you stack billions of instructions together and execute them across multiple threads and cores, these non-determinisms compound into all sorts of hard-to-reproduce bugs.
Two different ways you could do hybrid bonding are die-to-die and die-to-wafer. Maybe you can talk about the advantages of both and which one actually works better in practice.
Sure. Around Intel, what I think you’re referring to as die-to-die, we typically call wafer-to-wafer. We actually take a full wafer and another wafer and bond them together. That’s an approach that’s really popular in the CMOS image sensor industry. In fact, it basically dominates it.
It’s being looked at for other things, like memory stacking. People have published ideas about all kinds of stuff. One of the challenges with that, though, is that you need dies that perfectly match each other and are perfectly left-handed and right-handed, so you have to be able to bond exactly one to the other. One-to-one die size is a challenge.
If they’re not the exact same design device on top and bottom, that’s a problem. With wafer-to-wafer, it’s challenging to make sure that you have wafers that match really well in terms of the sort. So, sort good die here versus sort good die here. If they match exactly—good die and bad die all match—I can get 100% yield of that operation on the good dies.
But the chances of that are very low. There’s going to be some randomization between the two, and whatever that randomization is, there will be a loss from good bonding to bad. Whereas with chip-to-wafer, I can dictate the terms. I can singulate and have known good dies that I’ve tested at the chip level, and then only bond known good to a known good base position.
Do you think chip-to-wafer is the way that you’ll do hybrid bonding in the future?
I think we’re going to do both. We definitely have the capability to do both. It’s really customer- and architecture-driven, but certainly chip-to-wafer in the logic-to-logic space makes a lot of sense.
You were explaining that, going from advanced packaging to hybrid bonding, the size of the pitches is decreasing. How much further could that go?
That’s a wonderful question. Historically, like we were saying, 15 years ago, first-level interconnect was 130 to 150 micrometer pitch. Today, in HVM, we’re doing 25 micrometer pitch in Foveros. Here, we’re doing sub-10-micrometer pitch, but there’s already been literature out there.
In fact, the biggest conference every year in packaging is the IEEE ECTC conference, which happens in May. There was a paper there this year showing reliability data on a 0.45-micron-pitch hybrid-bonded device. So you can imagine that’s a whole other order of magnitude in density from where we are right now in HVM. That scalability has already been proven, so I see a long runway there.
Within interconnect, within a single wafer, how far separated are they usually?
In the back end of the fab, you can imagine the few layers below packaging are typically around 1 to 0.5 microns in size. So if you can push packaging down to 0.5 microns or below, you can almost think about taking layers off the top of the die and connecting a lower layer within the silicon to another lower layer within the silicon. That’s really where the beauty of hybrid bonding happens.
You could think someday about even having reduced interconnect layers on both sides that we can bond together and have less total IR drop between the two transistor layers. It’s really cool to think about where that could go once we get into those regimes.
Actually, I’m very curious about this. For AI, it makes sense why hybrid bonding is so powerful, because then you can get higher bandwidth to the memory. But you were saying there are issues with heat and everything. What is the advantage of hybrid bonding for non-AI applications?
Excellent question. There are companies out there that are looking at it for non-AI applications, even in client devices. One of the big things I think it can help with there is, number one, obviously, the same raw interconnect density, especially between something like a CPU and a GPU. But the other one is around power.
Like we talked about before, as you get to finer and finer interconnects, you can reduce the total power consumption, in picojoules per bit, for that interface. With hybrid bonding in those applications, you could think about that as another way that packaging can help reduce the total system power budget. That gives you lots of benefits: lower power, less heat, for the same benefit in terms of actual electrical performance.
10. There aren't enough tools to 10x chip production
So far, this has been about making better chips. The other half of the question is how many chips the industry can make if AI labs are willing to pay for far more of them. I’m getting a chance to talk to Pushkar Ranade, who is the CTO of Intel. I’m very interested in understanding how the fact that the entire industry has to rely on the same suppliers bottlenecks your ability to ramp up production.
For this EUV tool, ASML produces fewer than 100 of them a year. They don’t plan to produce more than 100 a year, or significantly more, even by the end of the decade. That has to be split between you, TSMC, and all the memory makers who are ramping up production, like SK Hynix. How does that limit your ability to scale up to all this demand?
It is a limiter. We have to make the most of the capacity that we already have installed. We’ll try to increase the output from our existing fleet of tools. But EUV or ASML is not the only bottleneck.
It is definitely a bigger bottleneck than some of the other tools, but to a large extent, we’re seeing tremendous supply shortages across all equipment. Even though there are multiple providers of other tools, once you lock into a process flow—let’s say 18A, which is a mature process now—we need a specific tool. We can’t just go and get a different tool for the same process. So we’re locked into that one tool, one supplier, and we rely on that.
What lessons does this give for 14A in terms of how you structure it? By 2028, it’s going to be such a crazy world. How do you structure things in such a way that you have flexibility in ramping?
The way to do it—and we’ve been doing it, and generally everybody does it—is you try to maintain as much fungibility as possible going from one node to the next node. Going from 18A to 14A, maybe you would say 80% of the tool set can be reused. Then, of course, 14A would require some new capabilities because it’s a denser geometry, so it would require some unique tools.
Do you have a sense of what the ultimate bottleneck is on how many wafers you guys could produce a month, even if you were to decide to invest infinite money into doing CapEx?
Given the existing constraints, let’s say we had to maximize the output from a given footprint of tools, then I think it’s incremental, because the process today is already yielding pretty high. If your yield is already pretty high, getting every 1% extra yield is extremely hard because it’s already a finely tuned process.
Are there enough tools in the world so you could 10X the amount of wafers you’re producing at the leading edge?
Not 10X, but probably 2X, yes.
That’s quite interesting, because the AI industry for a decade has been 3X-ing compute year over year. You’re saying that just can’t continue. Unless the entire supply chain—starting from the equipment suppliers, their suppliers, their sub-suppliers—produces more, you can’t increase the output.
Just to give the audience a sense of how big the AI demand is and how well it monetizes the products you guys are producing: you can crunch the numbers, and they seem to suggest that just a couple billion dollars of CapEx on Intel’s part results in enough chips—or the logic for enough chips—to produce, say, $100 billion of revenue for the AI model companies. Of course, there are so many other players within that stack. There’s also memory and other things.
But it’s crazy that a couple billion dollars of CapEx, which can be amortized over many different years, produces $100 billion of revenue every single year. That seems to suggest that at some point that should percolate down. At some point, the AI labs could just say, “We’ll just buy everything. Produce as much as you can. We’ll guarantee future income streams.” There are early signs that could actually be happening already. The demand signals are just so high.
But I think you were alluding to how the value is accumulating at the top of the technology stack. What is essentially happening is that we moved from a fully vertically integrated industry 30–40 years ago, maybe longer, to a very horizontal industry, where you have foundries, equipment makers, and their suppliers. Today, every hyperscaler is designing its own chips, and the scale of the hyperscalers is so large.
Some of the model companies, for example, have such high demand that they could easily consume an entire fab’s worth of silicon on their own, or multiple fabs’ worth, and they definitely have the capital to fund that. So, in some sense, we are moving from a horizontal world back to a pseudo-vertical world. It’s not monolithically vertically integrated, but it’s kind of virtually vertically integrated.
11. Can Intel catch up to TSMC?
What is the nature of economies of scale in this business? If you look at how many wafers TSMC versus Intel is shipping at the leading edge, it’s upwards of 3x for TSMC. What kinds of advantages do you get at this point from economies of scale? Or is it that once you reach a certain point, the economies of scale get weaker?
That’s a very important question. This entire business just relies on economies of scale. If you look at all the advanced manufacturing companies out there, the scale economics in semiconductor foundries is probably the purest. The reason for that is the fixed cost is just so incredibly high. Once you build a fab, about 80% of your cost structure is fixed.
What that means is every extra percentage of utilization adds far more in revenue. So it’s extremely important. We’ll fight for every extra percent of fab utilization, but also every extra percentage of fab output. Let’s say I’m making some wafers today and the yield is 60%. If I improve the process and the die yield becomes 65% or 70%, it’s not a linear advantage. I’m getting way more output for the given footprint. So there’s always room to improve the economies of scale.
That’s one of the reasons why you’re seeing so much consolidation in this business. There are only 3 foundries left at the advanced node for that exact reason. Along the way, many companies just stopped manufacturing. I don’t know if you’ve seen the chart: 40 years ago, there were about 20 foundries. Over time, the number kept diminishing until today, when there are only 3.
What is the concrete master plan to catch up to TSMC? Even though TSMC is ahead, there’s so much overflow demand at its leading edge, where N3 is now majority AI accelerators and maybe majority Nvidia alone. There’s all this demand for CPUs and other things, which are also needed for AI, by the way. There’s a humongous influx in demand for CPUs because of AI. How do you see this opportunity right now, where Intel’s a few years behind while TSMC is just way oversaturated?
Catching up to TSMC has multiple facets. The catch-up that we need to do is in scale. Like you said, they’re just a much larger wafer manufacturer today than we are, and even bigger than Samsung. Catching up in scale will be a gradual process.
If you meant catching up in terms of just the technology, I think we’re already there. We might be a few percent off on performance, power, or area density. But this sort of benchmarking, where one foundry is ahead or behind, makes sense when you’re a whole generation behind or two generations behind or ahead. That’s when it makes a meaningful difference in your die output, your die area, or functionality like power.
But if you’re within a few percent, you’re splitting hairs at that point in time, because it’s not very unidimensional. It’s not just about density, and it’s not just about raw performance. Different applications require different vectors. You can be off by a few percent, but you need to be on time. Your execution needs to be such that your yields are very high to support very large and very rapid ramps. That actually is more important than catching up on a few percent in performance or area.
I was looking at some SemiAnalysis numbers that seem to suggest that, in terms of transistor density, 14A—which will come out in 2028—would be comparable to N2.
First of all, I would dispute your benchmarking. But like I said, it’s important to be generally in the right ballpark and be very predictable. Also, it’s not unidimensional. We don’t build one type of transistor, let’s say 14A or 18A. You build a few different types of transistors.
There’s a low-leakage transistor, and there’s a high-performance, high-drive-current transistor. You’re building SRAMs. There’s a high-density SRAM and a high-performance SRAM. There are many other functionalities, like analog circuits and RF circuits. It’s the sum of all of those that makes a technology competitive.
I guess that makes the CapEx you do right now even more important. TSMC is on track to do around $50 billion in CapEx this year. You’re on track to do around $20 billion. If the tools you’re buying right now will determine who can service all this crazy AI demand that’s coming up, it makes the difference in CapEx right now even more important, or for the U.S. versus other countries.
Yes, very much. It’s a little bit of an unfair comparison between us and TSMC today, just because they’re a foundry for basically everybody and we’re largely a foundry for Intel. We’ll become a foundry for others. In due course, our CapEx will also grow.
Intel started as a DRAM business in the late ’60s. You guys were producing DRAM, which you sold off. A couple of years ago, you sold off your flash business. Thoughts on that? For context for the audience, these are now multi-trillion-dollar industries because they’ve just exploded as a result of AI demand. Clearly, in hindsight, probably not the smartest time to sell off a flash memory business.
There were good reasons why we did that when we did. Clearly, nobody could see this enormous demand. But today, the world will eat up as much compute as can possibly be made, and it’ll eat up as much memory as can possibly be made. I would argue that the supply crunch is larger for memory today than it is for compute.
Can I summarize what seem to me to be the takeaways from your projections? You can tell me if that’s correct. Marginal production can actually increase very fast—on the scale of 12 months—but the amount of increase up until the end of the decade is extremely limited. Production could be higher next year than what people are forecasting, but production in 2030 is not going to be significantly higher than what people are forecasting, unless the entire supply chain ramps up production very quickly.
We’re already in the middle of ’26, so there aren’t that many years until the end of the decade. Given the lead times, let’s say you place an enormous order for tools today, and you’re looking at 18 months to get those tools. You’re already into basically ’28. From that point on, if you have to build a new shell, build a new fab, you’re basically looking at the end of the decade.
12. Terafab, and rethinking the fab from scratch
I think it’ll be interesting to discuss the partnership you guys have with Elon on Terafab. What’s going on there?
Well, Elon’s publicly talked about his desire to build a fab. “We either build the Terafab or we don’t have the chips. And we need the chips, so we’re going to build the Terafab.” It’s sort of the same thinking. He’s seeing just an enormous increase in demand for silicon, for compute, and for memory. I think he came to the conclusion that his own businesses are going to require a lot of silicon. He thought maybe he should just do it all on his own.
But unlike building a car, for example, this is such an intricate and complicated process that we thought we could work together to help accelerate his bringing up his fab.
But because of the bottleneck at the tool level, it seems like the net amount of silicon in the world won’t increase. It’s just that maybe if somebody were to start a new fab, they would get access to guaranteed supply in a way that they wouldn’t have if they were working with another person’s foundry.
It’s not just tools. A fab does require a lot of power, a lot of water, and a lot of consumables. There are many other input variables as well.
But those can be scaled in a way that tools cannot. Some more than others, but yes.
In one sense, yes, we need a lot more equipment. But it’s true that we also need a lot more raw fab space, raw clean room capacity. If you think of a foundry like Intel, which has to build these expensive facilities and buy expensive tools, I wonder what you think the economics of that could fundamentally look like—whether it could get more economical, whether it could scale faster.
Like I described earlier, this is an extremely capital-heavy business. If you plot how much it costs to build a fab over the last 20, 30, 40 years, I think it’s doubling every 4–5 years. Even inside the fab, if you look at the cost of lithography, which is the most expensive module—just patterning—that itself is doubling at more than that rate. Today, a High-NA EUV scanner and all its associated equipment cost around $400 million.
So what does that mean? If that rate were to continue, if you just draw the line, does that mean four years from now the cost of patterning is going to be around $800 million? It doesn’t really make sense. A very interesting thought exercise is to ask: are there things we could do today that are radically different, but that we perhaps couldn’t do 20 years ago?
This is a very risk-averse industry for a very good reason. You put in tens of billions of dollars, and you really don’t want to take any risks. You want to keep doing things the way they’ve been done for literally decades. This isn’t just true of semiconductors, but of everything, really. If you’ve just kept doing that for decade upon decade, you become indoctrinated.
There are engineers who probably work at Intel who are new, who come in and are taught, “This is how the fab works. This is the process flow.” They just take that as gospel. That’s just how it’s done. But is that really the best way to build a chip today? It’s a really valid question.
I’m very curious what you’re hinting at, because it could be anything from figuring out ways to use fewer litho passes and economize on this expensive component to maybe rethinking the transistor. What is the level of—
All of the above. Transistor architecture is evolving. The silicon transistor has continued to evolve over 30, 40 years, and that will continue. You’ve seen the evolution from the planar transistor to FinFETs to now gate-all-around transistors. There’ll be more. That roadmap exists; it’s pretty well defined, with a lot of people working on it.
But there are things like: do you really need a clean room today? Do you need the infrastructure to be as sophisticated, as complex as it is today? Surely one could run an experiment where you have people eating hamburgers and smoking cigars in the research fab and see what happens to yield.
That would be a great experiment to run, but no incumbent—Intel, TSMC, or Samsung—would willingly do that. That’s what I meant by this. It’s a very risk-averse business, for good reason.
Every one day lost in productivity is—I don’t know how many dollars. But you save so much money in not having to build clean rooms in the future.
But it’s really the risk, the fear of the unknown. Nobody is going to willingly take that risk. That’s why I think sometimes it’s good to just start with a clean slate and rethink everything.
The same thing applies to chip design, by the way. Many of the ways we do CPU design were probably locked in 30 years ago. Does that mean it’s smart to still do it the same way? Probably not. But this is a very complex problem.
In chip design, I guess the capacity to take risks is maybe higher. This one, less so. But given where the economics is today, I think it’s a very valid question to ask. Maybe there’s a smarter way to do this.
To close out, maybe we’ll start with the same question we began the interview with: how does Intel respond to this crazy AI demand that’s incoming and has already arrived? It sounds like what Intel ought to do, if the ultimate bottleneck is that you already have these foundries and the ability to expand them, but will eventually lack the tools from upstream in the supply chain, is raise as much capital as possible right now.
The same way that Nvidia has locked down memory and other components for reportedly hundreds of billions of dollars’ worth of commitments, Intel should maybe do the same thing: make all these commitments so that over the coming years, the US is in a good position to have the bulk of semiconductor manufacturing at the most advanced levels happening here.
You’re suggesting we should be buying a lot more tools, right?
Yeah, because it sounds like otherwise, in a couple of years, you’d just be in a position where you’re like, “Oh man, we could be making trillions of dollars right now, but all the tools are in Taiwan.”
Yes, that’s a very valid question. Had we known what we know today, we would have invested more like a year ago. Knowing what we know now, I think we’ll be investing more.