The recent death of the great science fiction writer Arthur C. Clarke prompted me to recall his famous three “laws” (from the 1973 edition of his book of essays Profiles of the Future):

1. When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.
2. The only way of discovering the limits of the possible is to venture a little way past them into the impossible.
3. Any sufficiently advanced technology is indistinguishable from magic.

The last law is a favorite in a world where very few of us have even the slightest idea how most of our essential gadgets work. But the first two laws I think are more interesting, and revealing.

In particular, the first law hits close to home for me. First, let us be clear what Clarke meant. He defined “elderly” in this context as any scientist over 30, or possibly 40 in some cases. Thus, I easily qualify as an elderly scientist, and some (who don’t quite know me well enough) might even regard me as distinguished. So I began to think about past pronouncements I’ve made as to what is “impossible” in the field of lithography. The most obvious category is next generation lithographies, where I have made many public statements of the kind “193 nm lithography forever” and “EUV will never work”. Could it be that I am a classic example of Clarke’s first law, and that I am “very probably wrong”?

I don’t think so. Let me explain why. First, I don’t think that EUV lithography is impossible. In fact, I am quite confident that the many smart people working on that technology will be able to demonstrate very high resolution with EUV and be able produce working high-end chips in the very near future. EUV lithography is not impossible, it is just uneconomical. Tool costs coupled with throughput (not to mention defects) will render EUV lithography fundamentally too expensive. The technology is certainly feasible, but the economic realities of semiconductor manufacturing are even more harsh than the realities of the limits of physics. The important question to our industry is not “Can you do it?”, but “Can you do it for a dollar?” EUV can’t, and in my expert opinion never will.

By the way, in 1999 Clarke added a fourth law: “For every expert there is an equal and opposite expert.” Keep that in mind when pondering my expert opinions on the fate of EUV lithography.