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Billions of Transistors on a Single Chip
cgi-bin writes, "IBM has reportedly developed technology to create "tens of billions" of transistors on a single chip. Intel's pentiums only have 27 million or so. The technique uses electron beams instead of the traditional optical lithography. "
1. Inorder to get the resolutions required in the future, photon lithography would have to go to X-rays that have a high enough brightness (i.e. You need a syncrotron X-ray source on site). For EBL, you just need a large source filament.
2. Masks for X-rays would need to be the same size as the actual features because there is still not a good method to make images out of X-rays so they use a shadowing technique. Not the case for EBL. Electrons use magnetic lenses to focus and have been used and designed for years. This actually allows you to build the mask in seperate parts and have the electron beam deflection put it all together for you as if it was all together.
3. Stepper motors don't need to be quite as acurate on positioning. This is because you can put in a simple feedback unit that examines where you are projecting on the surface of the wafer and deflection coils can position the beam exactly. This means that you can do lithography while the wafer is still moving! You couldn't do this in your wildest dream with X-rays.
4. Electrons have a very small wave-length at the acceleration voltages used (on the order of picometers). However, the real limitation for EBL is not the wavelength by lens abberations (pick up a good optics book) as well as space-charge effects (this happens because you are using a charged particle and they repel each-other giving a bluring effect). Even with all of this, some predict that you could get resolutions "easily" to the 10nm scale in lithography. No, we can't do atom manipulation with this technique.
5. No this technique does not use a focused beam technique (similar to scanning transmission electron microscopy), but it uses a plane-wave electron beam so that you can expose large areas at once (similar to stardard transmission electron microscopy), allowing for higher through-put.
Probably the major disadvantage for EBL right now is that we need more sensitive resists. The brightness of the EBL is still low compared to UV photon lithography, but I know of several groups that have come a long way with this one.
As another side note to this, Lucent Tech. has an EBL system just about at proof of concept called SCAPEL. Hope this clears up a few of the wrong ideas and helps people understand what this is all about.