I am now back in Austin, after spending the summer working for Dow Chemical (the Shipley photoresist group) in Marlborough, MA. Besides enjoying the much more pleasant temperatures of that northeastern clime, I had the great pleasure of getting to know (or know better) many fine folks at Dow (most especially my supervisor Jim Thackerary, whom I have known for 20 years, but now know of his favorite curse after a bad golf shot). One of the people I was glad to interact with was George Barclay, the R&D head for Dow Advanced Materials. Thus, I was a bit amused when, on the flight home to Austin, I opened up my current issue of Scientific American and there, staring at me thoughtfully from the inside cover, was an overly artistic rendering of that very same George Barclay. Dow is running an ad campaign to bring the “Human Element” of Dow to life. Thanks to the talents of the famous (and very expensive) photographer Albert Watson, Dr. Barclay has earned his new moniker: Gorgeous George.

A scene that I witnessed yesterday:

Congressman Barney Frank to (unnamed Intel litho engineer): “Your fly is down.”

Like many lithographers who have been at this business for a while, I frequently ran into Franco Cerrina, longtime professor at the University of Wisconsin, at conferences (mostly the 3-beam conferences). He was friendly, smart, hard working, and one was always glad to see him and for the chance to talk to him. He worked for many years on X-ray lithography, and has more recently applied himself to using nanofabrication techniques in biology. I recently reread some of his line-edge roughness papers, since he and his students did some of the early work in that area. He moved to Boston University last year to head up the EE department. Since I am spending the summer working in Boston, I had planned to call him up to visit him, to see what he was up to. It came as a shock to learn that he died in a photonics lab at BU on Monday. He was 62, rode his bike in to work every day, and apparently was in good health. More details can be found at:

http://www.bu.edu/ece/2010/07/13/professor-franco-cerrina-ece-chair-dies/
http://www.engr.wisc.edu/news/headlines/2010/Jul12.html

He will be missed by the lithography community.

Aloha is a great word. I enjoy the word first because when you use it or hear it, chances are you are on Hawaii. It is also wonderful for its marvelous ambiguity – it is used for both hello and goodbye, but means literally love and peace. It is both a word and a sentiment that I wish to use more often.

And I got to use it during the last two weeks of June, where for the third year in a row I attended Vivek Bakshi’s Extreme Ultraviolet (EUV) lithography workshop. The workshop was held at the Makena Beach and Golf Resort – formally the Maui Prince before they went bankrupt last fall (it is now owned by Wells Fargo). It is a resort in the old style, grand and beautiful, but with its glory somewhat faded, and its best days in the past. It is unclear when or how or if it will reemerge as financially successful. A metaphor for optical lithography?

After teaching a half-day introductory litho course on Tuesday, the workshop began early on Wednesday morning with a keynote talk by Jos Benschop of ASML. I learned that everything is progressing according to plan for ASML (are you surprised?). The critical next step for them is the delivery of the six “preproduction” EUV scanners that are now being built. The goal is to print the first wafer at a customer site with the first of these tools by the end of this year. Subsequent preproduction tools will roll out roughly every two months. Thus, 2011 will be a critical year for ASML, and for EUV lithography in general. Customers will experience what EUVL will be like in a roughly production-like environment. By the end of 2011, then, chip makers will be ready to make a very critical choice: buy multiple production EUVL tools from ASML for delivery in 2012, or not. It is not an overstatement to say that the future of EUV lithography will depend on the overall performance of the technology using these preproduction tools. If progress on the critical issues of source, masks and resists over the next 12 – 18 months is not sufficient, the technology could easily be abandoned by the industry, much the way 157-nm lithography was dropped in 2003.

Obert Wood of Global Foundaries gave the next talk. He has been painstakingly using the ASML alpha-demo tool (ADT) at SEMATECH in Albany to gain production experience with EUV lithography. This is not easy to do, however, when your scanner has a throughput of one wafer per hour. Obert also received Vivek’s lifetime achievement award for his 25 years of effort in the pursuit of EUV lithography (beginning at Bell Labs, back when it was called “soft x-ray”). Congratulations to Obert, a scientist that I respect for working diligently on a technology without becoming an advocate or losing his scientific objectivity.

My main research interest of late has been line-edge roughness, so I reported on the latest developments in my modeling efforts (much progress, but even more left to do). I also was very happy to hear Takahiro Kozawa and Seiichi Tagawa of Osaka University give papers on their seminar work in understanding the radiation chemistry of EUV resists. My good friend Mark Smith gave a talk as well (I had been needling him to come to this workshop for years), and I was happy that we were able to go snorkeling together just before he rushed off to the airport to make it home for his anniversary (thus cutting his trip to Hawaii short but preserving marital harmony). The value of an intimate workshop setting is in the interactions with the other attendees, and this workshop proved quite valuable to me in this regard. The 50 or so attendees included colleagues and friends both new and old.

As always, I brought my family and stayed for an extra week on the island. A bit of paradise in your life every now and again never hurts.

I met Steve Thornton almost exactly 20 years ago, when I taught a lithography class at AMD in Austin. Shortly after that I moved to Austin, and Steve and I become good friends. He worked in litho at AMD/Spansion for something over 20 years. Steve and I wrote the first paper on “tuning” the lithography simulator PROLITH to match experimental data in 1996, an idea that eventually led to the development of the AutoTune product. I still look at that paper as one of the best that I wrote. Now, thanks to OPC, calibrating lithography simulators seems routine, but it was new and interesting stuff 15 years ago. But mostly the time I spent with Steve was spent drinking beer, fishing and floating on lake Travis, arguing politics, and complaining about the semiconductor industry. Usually doing all of these things simultaneously.

Steve died yesterday after a year-long struggle with cancer. He had not yet reached the age of 50. His daughter Kelly is 9 years old, and his wife Phuong still works at Spansion. I have trouble even trying to imagine what they are going through. My heart goes out to them, and to all of Steve’s family and friends that, like me, can’t yet feel what it will be like to miss him.

"History is full of examples of supernatural events, and unless we are saying that we’re somehow more intelligent and educated, better equipped to understand unexplained events today than we were five hundred years ago, then we must accept the explanations given to these events by those who witnessed them.”

Bobby Henderson, The Gospel of the Flying Spaghetti Monster

From yesterdays New York Times, front page:

"We Have Met the Enemy, and He Is PowerPoint"

The corporatization of the US military has had an unintended consequence: the ubiquitous use of mind-numbing PowerPoint presentations in place of critical thinking. Soon, military analysts will be like most corporate managers and executives: unable to write a coherent sentence.

"When you're looking at truth versus gossip, truth doesn't stand a chance."

- Barbara Mikkelson, cofounder (with her husband David) of Snopes.com
Quoted in the New York Times, April 5, 2010

The “hottest ticket” of the week were the ASML and Cymer updates on EUV lithography progress. It was beyond standing room only for the ASML talk, with a line out the door of the conference room. I decided not to brave the crowds, since I knew what was going to be said: everything is going even better than expected; the project is on-time and according to plan; EUV is inevitable. I poked my head in for the Cymer update on building sources for the ASML preproduction tool (PPT). They have six sources under construction, but unfortunately they will ship with an expected output of 40W, 20% of the 200W required for the PPT to have a chance of meeting its 60 wafer per hour throughput goal. They plan to upgrade the source in the field in two steps, first to 90W and then to the final 200W. Challenging, to say the least. Of the three technologies that could easily kill EUV lithography, source power is the most obvious and thus will probably get blamed when EUV dies (the other two problems are resist performance and mask defectivity, both of which will also take much longer to solve than the industry’s timetable demands).

As I come to the end of the week, I start thinking of summing up my impressions of another Advanced Lithography Symposium. I attended only about 20% of the 340 oral papers presented this year, so my sampling is certainly far from comprehensive. Hopefully, though, my posts this week have given an accurate impression of the conference nonetheless. Several people mentioned to me that they were impressed with the progress being made on directed self-assembly polymers – it’s moving beyond a science project to become an engineering project, and the results are looking good.

Since I have complained repeatedly in past years about lying with graphs (no numerical labels, misleading axes ranges that hide variations, etc.), I seem to have created an informal graph-police among my fellow lithographers who alert me to what they consider to be the most egregious abuses. One new complaint: displaying two wafer maps and then claiming that the spatial signatures are correlated because they look similar. But why do ‘chi-by-eye’ when performing a real correlation, with a scatterplot and a correlation coefficient, is trivial to do? Is there something to hide, or is the author just being lazy?

Finally, here are some of my favorite quotes from the conference. First, the bar quotes – gems from lithographers with a beer in their hand:

“You spend $120M on an EUV scanner. The result? You get a space with three more photons than a line.” (From an engineer worried about line-edge roughness.)

“I just spent 18 hours exposing one sh!$ty wafer with EUV.” (A student talking about collecting experimental data on the ASML ADT.)

And finally, quoting myself speaking directly to the audience during my line-edge roughness talk” “Your LER metrology sucks.”

And so ends another intensive week of talking, thinking and drinking about lithography. I love this conference!

Attending a meeting like Advanced Lithography I always have one hope: that I will listen to a paper that makes me say “wow!” After the first two days there were no “wow” moments. But then it happened for me on Wednesday. It was the first resist session in the morning, and I saw why Greg Wallraff and Bill Hinsberg’s group at IBM Almaden Research is so unique. Linda Sundberg gave a paper that I found hard to imagine coming from anyone else’s lab. The problem was an old one, though with a modern twist: how big an effect is developer depletion, and how can we separate that affect from chemical flare (acid that evaporates from one spot on the wafer and then redeposits nearby). What made the paper so good was the approach – she didn’t ask “what’s the easiest way to figure this out”, but asked “what’s the best way to figure this out.” They built a flow-cell to send a very controlled, small volume of developer sequentially across a line of exposed resist patterns to see how CD varied with order of contact with the developer. Sunberg happily described the early failures of this flow-cell, the redesigns that gradually improved it, and how the final version worked. It was a good idea followed by systematic attacks on the inevitable problems leading to an answer to a question that we’ve been asking in this industry for 20 years. Outstanding work.

There were also very good papers by Vivek Prabhu of NIST and Vassilios Constantoudis of Demokritos (Greece) in that same session. I walked out for the coffee break remembering why it was I love this conference. Later that morning I saw a good paper by Kedar Patel of SanDisk on comparing LWR measurements for different next generation lithography (NGL) approaches. His data was excellent, but his conclusion that every NGL approach can meet the ITRS roadmap specifications for LWR was inexplicable. I always enjoy discovering a new student, coming to the conference for the first time, who has become turned on by lithography. Alessandro Vaglio-Pret is getting his PhD at Imec and he gave a wonderful talk on roughness post-treatments, a topic many have discussed but only Alessandro provided reliable data for.

I gave a paper on my approach to modeling line-edge roughness in the afternoon (it’s always fun to give a talk), then finally gave up on attending papers for the rest of the day. I was winding down my brain and turning the conference into a social event (one of its other important uses). I talked to so many people at the poster session that I forgot to see any posters. I hit up a few hospitality suites in the evening, then went to bed thinking that this was a very good day.