Awards > Awardee Interviews > Interview

Interview: William R. Wheeler

1996 Albert Nerken Award Recipient
Interviewed by Daniel Bills, October 16, 1996

BILLS: I'm Daniel Bills. This is Wednesday, October 16, 1996. We're in Philadelphia at the 43rd National AVS Symposium, and it's my pleasure this morning to introduce William R. Wheeler. He is Senior Technical Advisor to the vice-president of Metrology Division at Tencor Corporation. Bill is being awarded the Albert Nerken Award for his outstanding contribution to ultra-high vacuum technology. Bill, tell us how you got started in vacuum.

WHEELER: Well, actually I guess it started in college; I did some vacuum processing. But in 1943, I joined Sylvania Electric and worked in the vacuum tube industry for some 17 years, and of course, we dealt with vacuum every day. I took a glass blowing course there; we had the resident glass blower, as you used to have in those days, and fiddled around with the VG1A ionization gauge and learned all sorts of vacuum technology. Special materials, we were concerned with exotic materials a good part of the time, and we did a lot of cleaning. We picked materials that would stay clean as we put them in tubes; this was essential for long life in tubes. So it put me in good stead then, when I joined the Vacuum Products Division of Varian in the fall of 1960. I had a running start in generating ultra-high vacuum products. 

BILLS: Do you work exclusively on glass systems?

WHEELER: Oh, glass vacuum tubes. This occurred of course, while I was still at Sylvania, and no, I worked on ceramic-metal tubes and generated some new forms of the ceramic-metal seals.

BILLS: How do you think your tube experience prepared you for your vacuum apparatus?

WHEELER: Well, I am afraid I explained that already, but yeah, I was loaded when I got into the vacuum division.

BILLS: Why did you leave the tube industry?

WHEELER: It was more like the tube industry leaving me, I'm afraid. You remember that the transistor was invented in 1949, and then along came the integrated circuit and the handwriting was pretty much on the wall. 

BILLS: How did you happen to get into vacuum tube component development?

WHEELER: One of the last things I did at Sylvania was to build an advanced tube processing station, and it involved the use of Varian's, at that time, brand new vac-ion pump. It allowed me to make a system which was much safer to use - you weren't dependent on power failures as you are with vacuum pumps and diffusion pumps. It was much cleaner and more reliable. And so a couple of the engineers came over from Varian to see what I was doing, and I had an introduction. They invited me over to see what they were doing, and it seemed like a fine place to go.

BILLS: Did you enjoy the change?

WHEELER: Did I enjoy it? Oh yes, because I had been largely in government contract work up till then, and now that we had complete free reign - it was a start-up atmosphere, and of course, in a start-up, the technical people are the leaders. So we just had a ball devising all sorts of new products.

BILLS: You did work on ultra-high vacuum seals, right? What kind?

WHEELER: Well, early on, this problem arose that the vacuum flange seal that Varian was using wasn't really reliable enough for their application. Big systems were using 50 and more flanges, and so reliability after bake simply wasn't enough to support that kind of activity. So I was asked to look into seals, and we evaluated the presently available seals, and none of them had the reliability necessary. So we started to experiment on our own, and this is how the ConFlat flange was born. Almost through a fluke, we had a junior engineer who had been with Varian for a couple of months, suggest using a conical seal surface, and I said, "Well, that may have advantages, but we can't put the conical surface on the gasket. It'll have to be on the flange." And there were some other practical ideas I had that the flange design should have, most particularly that the gasket should be thick enough and located snugly in the gasket cavity - that is, a small gap between the OD [outside diameter] of the gasket and the ID [inside diameter] of the flange - so that we'd have precision alignment of the flanges. This would be useful for a lot of purposes, and it turned out that that feature is what made the ConFlat work as well as it did. We went through some big tests and found that we could bake to 500C repeatedly for almost any number of times and the flange remained tight. This was such an advanced result over what we had experienced that we were ready to introduce the ConFlat flange to the world.

BILLS: How did you go about introducing it?

WHEELER: First, gave a paper at AVS in 1961, and that was printed in the Proceedings. After we had a patent. I had persuaded Varian management that it would be a good idea to offer the license to manufacture the flange at low cost.

BILLS: And we [Granville-Phillips Corporation] acquired one of those licenses!

WHEELER: You did?


WHEELER: Well, congratulations. You know, there were some people, who in spite of the low offering price, refused to do it [laughs]. The real standout was Vacuum Generators in England, and they said "There's no reason why we should pay that." But finally they decided that they would be social and join the club!

BILLS: We have used ConFlat for many years, and when they're made right, we've never found one that failed yet. It's a wonderful design.

WHEELER: I'm very pleased to learn that.

BILLS: Did the ConFlat seal analysis lead to other seal development?

WHEELER: Yes. After the first paper, I went back and tried to figure out why it was as good as it was, because I wasn't able to predict the result that we had. I devised a number of tests for getting quantitative figures on the pressures involved and the pressures obtained, and with that further understanding, it led first to the Wheeler flange. There was a problem, that we envisioned anyway, that as the flanges got bigger and bigger, that gasket supply would become awkward if you had to have stamping dyes to stamp out a two-foot gasket, for example. That sounded to me too expensive. So I devised a seal on the same gasket-capturing principles using wire. You could take a length of etched copper wire and cold weld it and stretch it to whatever size and shape you wanted, usually round. Wheeler flanges have been made up to ten feet in diameter. They worked quite well. I don't suppose that the reliability is as good as the ConFlat, but it certainly approaches it.

BILLS: Did you develop other kinds of vacuum products?

WHEELER: Yeah, all kinds. Because I knew about ionization gauges, for example, I got the job of doing the Varian nude gauge, which was the first, I think, really successful nude gauge. I used the kind of construction that we used in vacuum tubes to make it. Later on, I did a high-pressure ionization gauge, and then finally I did the production version of the Helmer gauge, which read down to 2 x 10-13 [Torr]. It was a shame that that one was not a commercial success at first because it got discontinued far too early. 

I did all sorts of feed-throughs: electrical, mechanical, motion feed throughs. I did the first five-axis manipulator that the physics people used for performing experiments. And seals, I developed a seal with a captured copper alloy pressed against a flat sapphire surface in order to generate a leak valve which could operate over 10-12 decades of leak range and pressuring.

BILLS: That's still being sold, right?

WHEELER: That thing is still being sold, 35 years later.

BILLS: 35 years. That's a pretty good product line!

WHEELER: Yeah, that's a good product line. In fact, there were a lot of things that we developed at that point that are still in the catalog. 

BILLS: That's amazing. How do you sum up your career in UHV products?

WHEELER: I thoroughly enjoyed it. At Varian, the technical people had free reign at the beginning, and we started to run a yearly symposium where we all talked. We delivered the symposium in various parts in the country. It was a very enjoyable experience, but as time changed, management changed and the rate of development certainly fell off, and it was time to move on, eventually.

BILLS: What are you doing now?

WHEELER: Well, 20 years ago, I joined another start-up - I love start-ups - which became the Tencor Corporation. We build technical instruments for the semiconductor industry and others, and I've been long-term associated with profilometers, which have been getting more and more complex and more and more capable as time goes on. Our profilometers now can measure roughness down to one angstrom Ra, sometimes better, and we are just about to release a new profilometer built on normal profilometer standards which is going to be directly competitive with AFM. We generate pictures that look just like AFM pictures.

BILLS: That's amazing.

WHEELER: Yeah, that's quite a coup, we think.

BILLS: Okay. Well, thanks for sharing this information with us, Bill, and congratulations on your Albert Nerken Award.

WHEELER: Thank you very much. Congratulations to you.