editor's blog
Subscribe Now

Laying n-Type Epi

Dopants used to be there just for their doping. But stress is now an important aspect as well, which means the dopant atoms must be sized appropriately as compared to their silicon hosts. This has worked for p-type, where compressive stress is desired. Germanium, which is larger than silicon, compresses the silicon, increasing hole mobility.

n-type should be the reverse: tensile stress is needed, meaning smaller dopant atoms. Phosphorus and carbon are both smaller and can work. Sounds simple, right?

Well, apparently not so. The n-type dopants have a tendency to migrate, and so far increased border security hasn’t worked. OK, kidding. About the security, that is. The migration has remained to be solved.

At Semicon West, Applied Materials announced that they had found a way to create a stable n-type epi layer. How do they manage it, you ask? Keep asking… they’re not telling. There was a mention of millisecond anneals helping to tweak any vagabonds before they get too far. And whatever they do sets up a strict thermal budget, although not so low that it affects the back-end interconnect processing.

Details aside, if this is all working as promised, then we have more control over how to optimize the performance of n- and p-type devices. You can read more in their release.

Leave a Reply

featured blogs
Nov 19, 2018
At the Linley Fall Processor Conference recently, the keynote on the second day was by Cliff Young of Google titled Codesign in Google TPUs: Inference, Training, Performance, and Scalability . The TPU is Google's Tensor Processing Unit. It is actually a family, since, as...
Nov 16, 2018
If you aren'€™t from the packaging world, then chances are likely you might think '€œpacking'€ refers to objects being placed in to a box instead of packaging integrated circuits (IC'€™s) on a substrate. Packaging has advanced since it began, and as with many areas i...
Nov 14, 2018
  People of a certain age, who mindfully lived through the early microcomputer revolution during the first half of the 1970s, know about Bill Godbout. He was that guy who sent out crudely photocopied parts catalogs for all kinds of electronic components, sold from a Quon...
Nov 13, 2018
Podcast Interview with the authors of The Hitchhikers Guide to PCB Design eBook by Mike Beutow with PCB Chat....