The Silicon Roadmap an industry development plan to continue reducing transistor size identifies basic problems to be solved. One involves the implanting of boron to produce increasingly finer features. In the subsequent annealing to restore the material s high conductivity, the boron diffuses 10-100 times further than expected, making features larger than desired, perhaps blocking the roadmap. The suspected culprit is the interstitial silicons that are kicked out of their lattice positions during the implanting. Electron microscope pictures show plate-like defects that might be the interstitials.
Computer modeling finds that planes of interstitials are amazingly stable.
This seems surprising since interstitials should disrupt the four-fold bonding that stabilizes materials such as silicon and diamond. The modeling reveals that interstitial chains can form planes with only four-fold bonds except at the ends of the chains hence the planes cost little energy to form. Using parameters deduced from this work, others can study the diffusion of boron in the presence of the silicon interstitial planes. Perhaps a way around the roadblock can be found. Everything is a lot.