It seems I can’t go a month without seeing at least one article decrying the end of Moore’s Law and another which shows that it’s still on track. Ultimately this dichotomy comes from the fact that we’re on the bleeding edge of material sciences with new research being published often. At the same time however I’m always sceptical of those saying that Moore’s Law is coming to an end as we’ve heard it several times before and, every single time, those limitations have been overcome. Indeed it seems that one technology even I had written off, Extreme Ultraviolet Lithography, may soon be viable.
Our current process for creating computing chips relies on the photolithography process, essentially a light that etches the transistor pattern onto the silicon. In order to create smaller and smaller transistors we’ve had to use increasingly shorter wavelengths of light. Right now we use deep ultraviolet light at the 193nm wavelength which has been sufficient for etching features all the way down to 10nm level. As I wrote last year with current technology this is about the limit as even workarounds like double-patterning only get us so far, due to their expensive nature. EUV on the other hand works with light at 13.5nm, allowing for much finer details to be etched although there’s been some significant drawbacks which have prevented its use in at-scale manufacturing.
For starters producing the required wattage of light at that wavelength is incredibly difficult. The required power to etch features onto silicon with EUV is around 250W, a low power figure to be sure, however due to nearly everything (including air) absorbing EUV the initial power level is far beyond that. Indeed even in the most advanced machines only around 2% of the total power generated actually ends up on the chip. This is what has led ASML to develop the exotic machine you see above in which both the silicon substrate and the EUV light source work in total vacuum. This set up is capable of delivering 200W which is getting really close to the required threshold, but still requires some additional engineering before it can be utilized for manufacturing.
However progress like this significantly changes the view many had on EUV and its potential for extending silicon’s life. Even last year when I was doing my research into it there weren’t many who were confident EUV would be able to deliver, given its limitations. However with ASML projecting that they’ll be able to deliver manufacturing capability in 2018 it’s suddenly looking a lot more feasible. Of course this doesn’t negate the other pressing issues like the interconnect widths bumping up against physical limitations but that’s not a specific problem to EUV.
The race is on to determine what the next generation of computing chips will look like and there are many viable contenders. In all honesty it surprised me to learn that EUV was becoming such a viable candidate as, given its numerous issues, I felt that no one would bother investing in the idea. It seems I was dead wrong as ASML has shown that it’s not only viable but could be used in anger in a very short time. The next few node steps are going to be very interesting as they’ll set the tempo for technological progress for decades to come.
