Although the transition to 300mm Si is in progress now,it is slowed by the recent slump in the semiconductor business. 200mm will be around a looooong time as it will be profitable to make certian types of devices on the older equipment. [Even 150 mm fabs are still making some older style but still useful devices. Hell, I work in a 100 mm fab, but we still get to do some additional interesting micromachining work... ].
Despit the remanent smaller sizes, there has been talk, and even some serious crystal growth work, and calculations for 400mm wafers. [The effect of Dan's conversion blunder is hearby slightly obscured] The capital costs in these fabs can run in the 2-10 billion dollar range for state of the art. A single process tool can easiliy be in the 1-6 million dollar range. This is an important technology area left to the competition of only a few of the largest corporations that can afford these investments. This leads to an inherent conservatism and bottom line mentality perhaps?!?!? The revolutionary ideas are harder to develop in universities unless they ally with a big company to get access to the latest equipment. -Jay