All posts by Chris

General

The best governement

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I like philosophy, especially arguments about philosophy. And if you throw in a little religion or politics, things really get fun. But in the end, I’m a practical kind of guy. I can’t be bothered with any philosophical musing that can’t be brought to bare on how I live my life. Here is a very simple example.

There is an oft repeated quote about the size of government: “That government is best which governs least,” attributed to Thomas Jefferson though it appears in none of his writings. What exactly does this mean? The least amount of government is no government; thus, it literally extols anarchy. Assuming that most who repeat this quote are not promoting anarchy (it is, after all, a part of the Republican Party oath), what is meant by this phrase? It is akin to saying “I believe in small government” without having to be bothered with defining what is meant by “small”. Thus, it claims to represent a philosophy, but without committing the adherent to any course of action. If no government and an all consuming government are both bad options (and surely all rational people must think that they are), there must be some optimum size of government, so that more or less government than this optimum is detrimental to the general welfare of the populous. It should be our goal to find the optimal level of government. How is this optimum to be determined? How, in fact, is the size of government to be measured? What criteria are best used when defining the benefits and detriments of government? These questions are not answered, and in fact not even asked, when one simply repeats the fine sounding but meaningless phrase “That government is best which governs least.”

Microlithography

Who invented pellicles?

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A question to the lithography blogosphere: who invented pellicles for photomask protection?

Lithographers have been practicing safe exposures – with masks wrapped in a thin sheet of plastic to protect them from particles – since before my time. What is the first reference to pellicles in the literature? Who was the first to use them? The earliest reference that I have found is Ron Hershel, “Pellicle protection of integrated circuit (IC) masks”, SPIE Vol. 275 (1981) pp. 23 – 28.

General

Greetings from Hong Kong

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It is not the shortest business trip I have been on, and it is not the longest. But somehow it feels like both.

After spending about 24 hours to get here from Austin, I arrived in Hong Kong on Thursday night. I’m here for a trial – I’m an expert witness in the case. But when I checked into the hotel, a note was waiting for me – the two sides had settled, so there was nothing for me to do. I changed my flight back to Saturday, and another 24 hours of travel time later I will be home. Thus, a very long, short trip.

But I did have a half-day free, and remarkably I managed to find a brew pub (go figure). The Hong Kong Brew House was in Lan Kwai Fong, the bar district of Hong Kong. While none of the beers were outstanding, they were all good (or at least acceptable). And you have to like it that someone in Hong Kong is trying.

General

The North Pole

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I have a good friend, Erica Lloyd, who is a science writer. She’s on her way to the North Pole, accompanying a science expedition to explore the sea floor up there. I’ve been following the daily photo updates on the mission’s website: http://divediscover.whoi.edu/expedition11/daily/index.html (apparently there is internet access on the North Pole – who’d of figured?). Fascinating stuff – I’m envious of Erica. She’s actually seeing the North Pole while there is still ice.

BTW, someday you’ll be able to hear Erica’s reports on the NPR show Radiolab.

General

Climate versus Weather

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The topic of climate change is, naturally enough, a hot one right now. But most people who are not climate scientists have a hard time grasping even the meaning of the word climate, let alone the implications of climate change. In conversations with friends and acquaintances, climate is invariably confused with weather (one of my favorite sayings when the temperature outside is too cold for my liking: “Where is global warming when you need it?”)

Climate and weather are very, very, very weakly related. Here is my favorite analogy: The weather is like how much change is in your pocket. The climate is like how much money you will earn in a life time. Of course these two quantities must be related in some way, since I did earn the money that’s in my pocket. But on any given day there is essentially no correlation between the two. And if I want to estimate my future earning potential, I won’t go counting the change in my pocket for clues. So let’s wise up and stop asking the weather man for his opinion on climate change, and don’t even bother asking the climate scientist if he thinks it will be a hot one this weekend. Besides, I live in Austin, so I already know the answer to that question.

Microlithography

New paper published today

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An article I wrote, “The Future of Semiconductor Lithography: After Optical, What Next?“, has just been published. It is available online at the Future Fab International website.

A definite advantage of being unemployed (er, I mean, a Gentleman Scientist) is that I can pontificate without worry as to who I offend. And this article porbably has a little bit to offend just about everyone in the next generation lithography community.

Microlithography

Chris, where have you been?

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I haven’t been blogging a lot lately.

This is obvious to the 2.5 people that regularly check my blog to see what I have to say. But I have a reason (there is always a reason): Since the first of the year till the end of May I was extremely focused on one thing – finishing my textbook on optical lithography. I spent the month of June on the French Rivera on vacation, but more on that later. I’d like to talk about that pesky book first.

The title is Fundamental Principles of Optical Lithography: The Science of Microfabrication. Quite a mouthful. It is my Opus Magnum – just about everything I have learned about optical lithography over the last 24 years, including quite a bit of new, unpublished research. Amazingly, I’ve spent 17 of those 24 years writing this book! And for most of those years it has seemed that I was further away from finishing each year that went by (a testament to how fast the field changes). I finally realized that near full time effort was required to finish the book, which is what I have been (almost) doing for the last two years.

A few statistics about the book:

Number of pages: about 600
Number of chapters: 10
Number of figures: 272
Number of equations: 973
Number of homework problems: 132

It’s not exactly beach reading.

The publisher is John Wiley & Sons, and the book should come out towards the end of November. If it is a best seller (as far as such textbooks are concerned), I won’t even come close to making minimum wage for the time I spent writing it. But of course, nobody writes such a book for the money. It’s about the glory.

General

Greetings from our Nation’s Capital

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I am writing late at night from Washington DC, where I am not following the advice of my lawyer to retire early. Tomorrow I am being deposed as an expert witness in a lawsuit – an experience, so I am told, unlike any other. But I’m not interested in talking about that, nor politics, nor the various memorials to famous dead people that I visited today. Instead, I want to talk about a bar.

I have just returned from the Brickskeller, a fairly famous local joint that is celebrating its 50th anniversary this year (it’s been a fixture of Washington life longer than most, but not all, of the politicians that tend to hang out it much more upscale bars than this one). What’s so special about this bar? It’s a cool little dive in an interesting part of town, not too far from the action but far enough to be a true neighborhood bar. The bartenders are friendly, carrying on conversations and knowing the city in Wisconsin where the beer you are drinking came from.

Oh, and they have a thousand beers to choose from.

Not on the order of a thousand, but actually one thousand beers. The menu goes on for pages. The number of beers on tap, of course, is much more limited, but I was still able to enjoy draft beers from Lyons (Colorado, not France), Wisconsin, Vermont, Oregon, Canada, the UK, and Russia.

In case you are wondering, the Brickskeller does not own the world’s record for beer selection at a bar. That honor goes to the Delirium Café in Belgium, which is reported to have 2,500 beers available (and so has earned the pink elephant that is their mascot). The Brickskeller, however, holds the record in the US, and the record in terms of bars I have been to. It almost makes me want to visit DC again soon.

Almost.

Microlithography

PMJ – Day 3

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The final day at PMJ had the papers most interesting to me (that is, more related to the use of masks rather than their fabrication). Here’s a few things I learned at the conference (if you’re not a serious litho techno-nerd, skip this bit):

• Mask makers have started to ask for resists that are less sensitive (shot noise has become a problem), after three decades of complaining that resists are not sensitive enough.
• The non-ideal behavior of a scanner has a noticeable impact on proximity effects, and thus on the behavior of OPC tools.
• EUV is hard to do.
• No one really understands line edge roughness.
• Double patterning sounds good to mask makers – they get to sell twice as many masks, but mask errors probably won’t be the number one problem facing the lithographer.
• EUV is really hard to do.
• At the 45 nm node, lithography will be the #2 problem facing chip makers (strain variability will be #1) – how disappointing!

Overall, the average paper quality at PMJ is about the same as at other SPIE-sponsored lithography conferences, but with fewer really bad papers and fewer really good ones. There was one presenter who seemed to randomly change slides, both forward and backward, without any relationship to what he was saying. A couple of papers had none-too-subtle marketing messages sprinkled between graphs of data and self-serving conclusions. And of course, there was the guy whose company wouldn’t let him present any data, so he removed the numbers from the axes of every graph (why did he even bother to present?). But I’ve come to expect this from a conference that caters mostly to industry, and the number and egregiousness of the violations of paper propriety were relatively small. Most papers described solid but small incremental advances – the kind of thing that has been pushing Moore’s law forward for 40 years.

Microlithography

PMJ – Day 2

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The second day of the conference has been eventful. One speaker went horizontal – fainted dead away – in the middle his talk. Apparently he is fine, but it was hard to tell as the paramedics took him away in a stretcher. It could have been nerves coupled with jetlag, or some bad tuna, or too much sake. I think, though, that he was done in by trying to make EUV masks work.

At lunch I was invited by some of the conference organizers to provide English lessons. As background, the conference, in Japan and run by Japanese, is carried on entirely in English. Now I am a typical American – unable to communicate in any language other than English, and just barely so in that language – so I have immense respect for anyone that is brave enough to commit to another language for an important endeavor. The people running the conference take their responsibilities very seriously, and asked for help in learning appropriate English phrases needed for conducting the business of conferencing. Is it better to say “In the interest of keeping on schedule, please see the author during the break if you have questions”, or “I’m tired of listening to this guy talk – let’s move on to the next paper”? I did my best to encourage authentic and appropriate phrases.

The day ended with a panel discussion from 6 – 8pm. The astute student of time might note the conflict between the timing of a such a technically fulfilling event and the emptiness of my stomach. Fortunately, the conference organizers anticipated this conflict and provided chips and beer. Less than fortunately, the beer was gone within nanoseconds of its availability – only the fast movers in this business reap the rewards of success. What did I learn from the panel? That panels always go better with beer.