Wayne Greene manages the Device Research and Applications Department, which is part of the ULSI Research Lab at HP Laboratories in Palo Alto, California. Wayne received his bachelor of science degree from M.I.T. and his doctorate in chemical engineering from U.C. Berkeley. In 1988 Wayne joined HP's Integrated Circuit Business Division, where he worked for six years on plasma processing of materials, device damage, transistor design, process integration, and technology transfer of advanced CMOS technology. He joined HP Labs in 1994. In this interview, Wayne discusses CMOS active pixel sensors, some difficulties surrounding Moore's Law, and other work under way in his department.

CMOS sensors have been more visible in the news lately. Why is the world now paying attention to these chips?

Traditionally, image capture for camcorders, surveillance, machine vision, and, more recently, digital cameras has used charge coupled devices for image capture. The CCD chip requires the use of many other support chips to provide a system solution. These CCD systems burn a lot of power. If you break open a CCD camera, you will see over 30 integrated circuits, all to provide a color-corrected and enhanced image. CMOS technology advances provide cheaper and denser diodes and transistors that now can be used for imaging. In 1994, the Jet Propulsion Laboratory re-invented the CMOS active pixel sensor technology, which has the potential of CCD image quality with lower power and system costs.

CMOS APS is a perfect example of a disruptive technology that is displacing the traditional use of CCDs. CMOS APS has displaced the CCD in the low end of the market -- for toys, biometrics, and PC videoconferencing -- and by 2003 should displace more than half of the mainstream CCD markets. Right now CMOS APS technology has poorer image quality -- because of leakage noise in the photodiodes -- but is being drastically improved. Just about all semiconductor companies are working on this technology, including HP.

Without giving away anything proprietary, what is your department doing in this area?

We view the CMOS APS technology as a key component of HP's image-capture business. Image sensors can be used in traditional market segments but will be even more pervasive than computers and printers in the consumer space. Specifically, we're researching improved APS pixels -- consisting of transistors and photodiodes -- in advanced CMOS technology. This means reducing the noise sources and improving the image quality. We pursue this activity through the close relationship between circuit design and process technology development. Critical to our success is our close interaction with image-quality and camera designers at HP Labs and within HP's divisions. We maintain a very close linkage with HP's Integrated Circuit Business Division, which is developing new businesses around this technology.

What effect do you think these chips will have? In 5 years, say, how common do you think these chips will be? And what will they let people do that they can't do now?

I firmly believe that CMOS APS will alter the consumer model. We'll see cameras smaller than a Palm Pilot, image-sensor recognition systems that you can buy at hardware stores and that compete for shelf space with keyed door locks, embedded image-capture capability in all sorts of consumer products, video-capable cell phones, digital camcorders. I could go on, but you get the idea. As with the Palm Pilot, I cannot even imagine how my children will use this technology. At the age of 2 my children already understood "directory structure" on my home PC. How will they use image sensors in their lives when they will ultimately cost less than a Slurpee? That is clearly the mark of a disruptive technology -- we cannot estimate the market potential because the consumer has yet to decide how to use it.

I have heard that there are a lot of challenges in producing systems-on-a-chip that incorporate both analog and digital circuits. Can you comment on the nature of the issues and how the industry will solve them?

HP Labs has been very concerned with addressing the concept of "MC squared" -- measurement, computation, communication. The physical world is analog while the silicon world of computation is digital. CMOS technologies need to interface the digital world to this analog world. This interface is key and is governed by the need to engineer solutions for higher-voltage transistors and passive components such as inductors, resistors, and capacitors within the core IC technology. This is a process issue in that Moore's Law dictates lower voltages and lower power while it has effectively neglected passive components. It is also a circuit design issue because high-level synthesis and portability to multiple fabs -- so critical for digital applications -- fail for analog applications.

Various mixed-mode processes have been developed by CMOS manufacturers, but they tend to be at least one generation behind. The industry is solving these issues by making the core process more complicated through multiple threshold voltages, supply voltages, and passive component insertion. It ultimately becomes a business decision of how much more wafer cost for what amount of increased functionality.

What else is your department working on that you can talk about?

The key mission of the ULSI Research Laboratory -- which my department is part of -- is to develop advanced CMOS technologies for HP products. We are currently working on both 0.18 micron and 0.10 micron process and device technologies. We are especially concerned with the escalating costs of keeping the industry advancing according to Moore's Law. We also see that in about 10 years traditional CMOS will run out of steam. Any company that highly leverages silicon technology in its products will have about 10 years to ride this technology. In about 2004, though, the industry will have to seriously fund fundamentally new technology research to satisfy consumers' expectations for continued gains in low-cost, high-performance computation.

We are also working on new CMOS technologies that will enable drastic changes in what consumers can accomplish. On the process side we add about one or two elements from the periodic table to the CMOS material set each year. At this point we are using over 30 elements to manufacture a wafer. On the design side, the work is clearly going digital. We are inventing ways to interface the digital world to the analog world.

You're HP's faculty mentor associate at Stanford and MIT. How do you feel about this part of your job?

We fund some key research activities at universities. There is a significant amount of outstanding academic work out there. In fact, I have observed over the past 10 years that universities have moved close to industrial labs in their research. While this is good for industrial labs, I believe that the current shift back to more basic research at the universities is required for the long-term competitive nature of our industry. Having a close interaction with universities lets HP and the university students gain from that research and also gives us some input in setting the tone of the future research.

How did you get interested in chemical engineering?

My first dream was to become a medical doctor, and chemical engineers appeared to have the best chance at acceptance to medical school. In high school, I donated my time to working with patients at a long-term health care center. Guess what? It was not for me. My next dream was to clean up the world from pollution. But when I was in college, funding for pollution control was drying up, and I also heard horror stories of chemical engineers being sent into oil distillation columns with toothbrushes to clean up. In 1983 I heard about this semiconductor thing, and I realized -- like Dustin Hoffman in "The Graduate" -- that the key to the world was "plastics." Without chemistry, life itself would not be possible. Now I manage great people who turn raw materials and intellectual property into advanced integrated circuits.

Were your parents interested in or work in the sciences?

They climbed the ladder like most immigrants did. I did have an uncle who worked on the Apollo space program. He was one of the many clean-cut guys in that big room that we all saw on TV. We actually have lot in common in terms of managing technology and people.

What do you do when you're not at work?

My family is really key to me. My wife and I believe in spending significant amounts of unprogramed time with our kids. I mountain bike the hills of the South Bay and rollerblade as well. I can't tell you how productive our vegetable garden is this year. Cross country skiing is on my mind as well. I do a lot of volunteer work at our synagogue as well.

What are you reading right now?

Although I read a lot of science fiction, I find that a lot of my reading time is consumed keeping abreast of new technology and of new consumer wants and desires.

When you travel, where do you like to go?

As a family we go to the Sierra Nevada and the beach for extended visits. We do a lot of camping. Little Basin was great this year -- except we were eaten alive by mosquitoes.