I’ve been doing some work lately as an expert witness, so I found the following factoid quite interesting. The most commonly quoted song lyric in judicial opinions is from Bob Dylan’s Subterranean Homesick Blues: “You don’t need a weatherman to know which way the wind blows.” How do I know this? The law professor Alex B. Long is described as the leading expert on music citations in judicial opinions, and his analysis can be found in an article in yesterday’s New York Times. Couple this with Arthur C. Clarke’s fourth law (“For every expert there is an equal and opposite expert”) and we see that, especially in a court of law, two expert weathermen will generally tell you the wind is blowing in opposite directions.
Monthly Archives: June 2008
Clarke’s Laws and Future Lithographies
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.
Aloha From the EUV Islands
Last week I attended the 2008 International Workshop on EUV Lithography on Maui. Many people who know me are perfectly aware of my opinions on EUV lithography (a doomed technology), and thus may wonder why I was attending an EUV workshop. Did I mention it was on Maui?
Actually, my current primary research interest is line-edge roughness (most likely the ultimate limiter of resolution for optical lithography), a topic of great interest to the EUV community (since it is killing them). I gave a talk at the workshop and presented a full-day course on line-edge roughness the day before the workshop began. And I had some very useful discussions on the topic with various other attendees – that’s the point of a workshop, is it not? I also got the chance to tell everyone during a panel discussion that EUV would never make it to high volume manufacturing (I have a habit of stating the obvious, even if no one else does). All in all, great fun.
The workshop was organized by Vivek Bakshi, who was recently “redeployed” (laid-off) by SEMATECH, along with all the other SEMATECH lithographers in Austin who couldn’t stomach a move to Albany, NY. Since SEMATECH’s main product is workshops, it is not surprising that one of their excess minions would start up a business (Vivek has called his EUV Litho, Inc.) to compete. SEMATECH was not amused. They made it very clear that all suppliers receiving SEMATECH money would not participate in this renegade conference. As such, the meeting became more academic and international, with virtually none of the “we’re on track, trust us” talks that the tool vendors always give at similar SEMATECH meetings. And besides, it was on Maui.
And I still am. That’s why this post is almost a week late. I’ve acclimated to island time – what’s the hurry? I brought my wife and two daughters, as well as my parents, who celebrated their 50th wedding anniversary on Sunday. Life is good. In fact, I am now sitting on the balcony of my room overlooking the ocean drinking a coconut porter from Maui Brewing Company. From a can. Life is good, but not perfect.
Lithography Word Recount
I was befuddled (rank: 53,829) by my recent experience with wordcount.org (see my previous post). It seems that the word ‘lithography’ is ranked appallingly low in frequency of use, relegating me and my life’s work to the denizens of the perennially unpopular. But something smelled funny. I began to think that WordCount was not very good at counting. Since I have spent a lot of time thinking about how to measure things over the years, I decided to do what I always do when I see a data point I don’t like: blame the measurement.
I began by looking into the website’s counting method. From the wordcount.org site:
“WordCount™ is an artistic experiment in the way we use language. It presents the 86,800 most frequently used English words, ranked in order of commonness… WordCount data currently comes from the British National Corpus, a 100 million word collection of samples of written and spoken language from a wide range of sources, designed to represent an accurate cross-section of current English usage.”
So WordCount is an art project. I suppose that doesn’t mean it couldn’t be accurate, though I suspect that accuracy is low on the list of success criteria for most artists. But what is the British National Corpus? I found the official BNC website, and this is what they said:
“The British National Corpus (BNC) is a 100 million word collection of samples of written and spoken language from a wide range of sources, designed to represent a wide cross-section of current British English, both spoken and written.”
British English! That explains a lot. I thought the word count would relate to real English. But since lithography was a European invention, and was certainly practiced in England, I’m not sure that this could explain lithography’s unexpected lack of popularity. True, England doesn’t have a semiconductor industry to speak of, so talk of semiconductor lithography over dinner is probably unlikely. But still, the frequency of use seemed too low, especially compared to ‘sciorto’.
I did a little more digging. Of the 100 million words in the collection, the word ‘lithography’ is used 47 times. That’s a pretty small count, even if the sample appears to be large. 100 million words is obviously not enough if you want good statistics at the tail of the distribution. The other words near ‘lithography’ on the list – luqa, calculi, tiverton, kaysone, sciorto, and bullingdon – were all tied with lithography. Digging further in the BNC website, I could even find the sources for those 47 word uses. This is where the fun begins.
Yes, Sciorto is an Italian family name, but Count Roman di Sciorto is a character from a romance novel called Calypso’s Island, the source of all 47 occurrences in the BNC. Talk about skewing the sample. Here is one example: “How ludicrous, after all, to have imagined that the great Count Romano de Sciorto, of Casa Sciorto, of the Città Notabile, the Noble City, could fall seriously in love with her.” Riveting. Tiverton, while certainly a city in England, is also a character from another romance novel, Hidden Flame, from which 19 of its 47 word-use references came. It seems that romance novels make up a fair part of the 100 million word collection. Almost every use of Bullingdon occurred on television news and refered to the prison of that name in Oxfordshire, England. What we have here is a phenomenon called ‘the sampling sucks’, caused by the lumpiness of an abysmally low sample size for these words. 100 million words seems large, but when you think about all of the words that are written and spoken in English each day, that number starts looking very small.
The bottom line is this: WordCount is art, and while it definitely has words, it doesn’t do a very good job of counting. You shouldn’t expect artists to count – that’s what nerds are for.
By the way, ‘recount’ is number 29,409 on the list. I think the wordcount.org folks need to move it a little higher up.
Lithography Word Count
II discovered an interesting website recently: wordcount.org. The site claims to have taken the 86,800 most common words in the English language and ordered them by frequency of use. It’s no surprise that the top ten words are, in order, ‘the’, ‘of’, ‘and’, ‘to’, ‘a’, ‘in’, ‘that’, ‘it’, ‘is’, ‘was’. Overcome by curiosity, I began typing in words to see how they ranked. ‘Mack’ is number 26,453. ‘Beer’ is 2,927. ‘Wine’ is more common at 1,634 (though I would have thought beer, the common man’s drink, would be more popular).
Then I typed in ‘lithography’ (the subject of my profession). I was shocked at the result: #42,832. There are 42,831 words in English that are more commonly used than ‘lithography’! Obviously, that is not true in my household, but could I be so out of touch with the rest of the world that I didn’t realize that lithography is in the bottom half of word popularity?
I decided to look at the few words just above ‘lithography’ on the list. Here they are.
42,826 luqa
42,827 calculi
42,828 tiverton
42,829 kaysone
42,830 sciorto
42,831 bullingdon
42,832 lithography
Are they kidding me? A word with a ‘q’ not followed by a ‘u’ is more popular than ‘lithography’? The only word I even remotely recognize from this list is the plural of calculus, and I can truthfully say that I believe that one calculus is enough. Is my field of study and work, the field that I have devoted the last 25 years of my life to, really this obscure? I guess so.
By the way, Luqa is a small village in Malta. Tiverton is an English town in Devon (as well as a New English town in Rhode Island). Kaysone is the first name of Kaysone Phomvihane, a former prime minister of Loas. Sciorto is an Italian family name. Bullingdon is an area of land in Oxfordshire, England, known as a “hundred”. The Bullingdon Club (or Bullingdon Dining Club) is a top-secret Oxford student drinking club for the super-rich. (Thank you, Google.) I look forward to using these words in conversation soon. I suspect there are a lot of words above ‘lithography’ on the list that I’ll need to learn.
But wait, there is more on this subject that must be told. Could there have been a measurement error? Stay tuned…