Probably the most important development in the past few decades for electronics has been Moore’s Law. Really it should not be called a “Law”, as it’s not really a “formal law”. In essence, what it is an observation that transistors doubled approximately once every 2 years. A Law is something like “the Laws of Thermodynamics”, a fundamental law of the universe.
Why does it even matter?
Imagine a world where next year’s model of computer, phone, and any electronic are not much better than the previous years. What really drove this was shrinking transistor sizes. Let’s call these nodes. Imagine if there won’t be another node next time. So in other words, next year’s shiny new toy isn’t going to be much better than this year’s. Sure there may be some incremental improvements, but they will be much smaller than before.
Does this sound crazy? We might be heading towards that world. It may very well be that 28nm is the cheapest node. So smaller and faster nodes can be made, but not cheaper per node. That remains a big “may” be though, and there are some technologies on the horizon (as always that are promising), but with immense technical difficulties. Certainly the difficulties that Intel has had since 14nm suggest so.
I think that the media in particular in how it has portrayed Moore’s Law has been dismissive. There have been a lot of claims over the years that it would die. I think we get this sort of “the boy who cried” wolf mentality and another reason is that many journalists do not have the technical background needed to comment on these issues. When engineers say that they think Moore’s Law is about to die, what they mean is that : “Here are some really big technical challenges and if we do not solve them, then Moore’s Law cannot continue. If we can solve them, then they can continue until we identify the next big challenge in the next node.” Previously in nodes, they have been solved and a smaller process came about.
At some point, I think it is inevitable that it will slow down. The problem is that the challenges get exponentially more difficult as you scale down. They are literally at war with the laws of physics. Heat and leakage become the bane of electronics and at some point they will win. Either the next node will be simply too expensive in terms of capital costs or the technical problems will be insurmountable. At the same time, compounding the issue, the marginal benefit of the next node is become more and more questionable.
As you scale down smaller and smaller, the challenges become exponentially larger. As I have noted, you are at war with the very laws of physics itself to get the node to work. Past 22nm, semiconductor engineers have become faced with pretty unique challenges like quantum tunneling.
Supposedly there were technologies out there that would come to the rescue:
- 450mm wafers: Basically all of the silicon chips produced today are produced on 300 mm wafers. Wafers today use 300mm ingots – 450mm (in theory at least) would allow for economies of scale. This would allow for reduced die costs and other economies of scale. In practice, it has been delayed by various challenges and is not expected until the mid to late 2020s.
- Extreme Ultraviolet Lithography (EUV): Computer chips today are made with a 193 nm laser that etches the changes onto the 300mm wafers I’ve described. Essentially EUV is a much higher frequency laser, which in theory, should allow for much greater precision. There appear to be various technical problems that involve its deployment, including providing enough power. Even if it were to work, it will be very capital intensive.
Both of these are critical for the long-term continuation of Moore’s Law and both of them have faced significant technical problems. These have caused delays and may outright prevent their deployment.
Even further out, there are unconventional solutions like graphene (which has a huge problem – no band gap, which is necessary for a transistor), but these are truly ‘blue skies’ type projects with an uncertain (at time of this writing) hope for success. Whether or not graphene will turn out to be the wonder material that it has hyped as remains to be seen. I certainly hope it does, but so far, it remains totally unproven. Other ideas like quantum computing remain long-term solutions that may or may not work out. Much like nuclear fusion power, it is always “a few decades away”.
In truth progress has already slowed down. Around 2005, Dennard Scaling, which meant that as the size of transistors got smaller, the power density was unchanged (so for example, a 2x smaller transistor would use 1/4 as much power). If you are interested, I’ve uploaded the original paper here. That no longer held after 2005, where power losses began to result in increases in power consumption and would have destroyed the chip had power consumption increased. The end result was that although we could etch smaller transistors with lasers, power density had to be held a constant. That was one reason why we have multicore CPUs – to spread out the concentration of power consumption and prevent a thermal breakdown. Unfortunately, not everything tends to scale very well. It is only a matter of time before the rest slows down.
The net effect
I pay close attention to Intel since it is the leader when it comes to semiconductor nodes.
Intel had experienced considerable difficulties with the 14nm leading to delays and there is still a Skylake CPU shortage. Meanwhile, the 10nm CPU node has been delayed and it is looking like the tick-tock model that Intel pioneered of an architecture one year, followed by a node shrink, then 2 years later another architecture has died. Barring a major breakthrough such as EUV, this is looking like the status quo for now.
At some point, either the technical problems will be so problematic that they are insurmountable or the costs of the next generation fab simply will not be economically viable.
The only scenario where this changes is if something fundamentally new such as quantum computer or graphene completely changes the game. Whether that happens anytime soon though is beyond the scope of this post.
So what if it does end?
I hope that Moore’s Law can continue in some form or another and that we continue to see faster chips for decades to come. However, I think given the challenges, it is worth considering a “what if” analysis.
That is what I plan to do in a part 2 of this analysis.