A sample of N-doped, single crystal Czochralski Si was subjected to several different surface preparations. Secondary ion mass spectrometry depth profiling had shown that prolonged glancing-angle bombardment by 3 to 5kV Ar+ ions significantly increased the N concentration in the near-surface by up to an order of magnitude above the bulk value. Concentrations were observed to be elevated over the bulk value to a depth up to 25µm. Nitrogen-implanted samples and samples with a 1nm surface nitride did not exhibit N segregation under the same conditions, but a sample with 100nm of surface nitride did exhibit ion bombardment induced drive-in. In nitride-free samples, the source of the N was indicated to be a N-rich layer in the first μm of material. The diffusion behavior of N in Si was considered, and the crowdion mechanism for diffusion was suggested to be the mechanism of enhanced low-temperature diffusion.

Segregation and Enhanced Diffusion of Nitrogen in Silicon Induced by Low Energy Ion Bombardment. N.Stoddard, G.Duscher, A.Karoui, F.Stevie, G.Rozgonyi: Journal of Applied Physics, 2005, 97[8], 083534