Out‐diffusion of nitrogen from float‐zone silicon measured by dislocation locking

Abstract

A measurement of nitrogen out‐diffusion from nitrogen‐doped float‐zone silicon made using a dislocation locking technique is presented. Specimens containing a well‐defined array of dislocation half‐loops are subjected to identical anneals at 750 °C, during which nitrogen diffuses both to the surface and to the dislocations. The specimens are then chemically etched so as to remove different thicknesses of material from the surface. The stress required to move the dislocations away from the nitrogen is then measured. The variation in this unlocking stress with thickness of material removed allows some measure of nitrogen diffusivity to be deduced. The result obtained is consistent with an extrapolation of SIMS out‐diffusion measurements previously performed at higher temperatures, but indicates a different activation energy for out‐diffusion to that associated with dislocation locking by nitrogen. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Measurements of Dislocation Locking by Near-Surface Ion-Implanted Nitrogen in Czochralski Silicon

“…Previous NFZ-Si nitrogen dislocation unlocking experiments 9,[26][27][28][29]32 used different three-point bend loads and durations for each test, which was found to contribute to an error in the results. In the present experiments therefore, standard conditions were used for every three-point bend: ϳ85 MPa maximum stress for 4 h, eliminating the error that existed in previous work.…”

Measurements of Dislocation Locking by Near-Surface Ion-Implanted Nitrogen in Czochralski Silicon

“…This is done after the three-point bend using a preferential etch, comprising CrO 3 (0.3M) and HF (40%) in the ratio 5:4, which creates etch pits at the position of dislocations which are visible under an optical microscope. Previous NFZ-Si nitrogen dislocation unlocking experiments (9,(26)(27)(28)(29)32) used different three-point bend loads and durations for each test, which has been found to contribute to an error in the results. In the present experiments therefore, standard conditions were used for every three point bend: ~85MPa maximum stress for a four hour duration, eliminating the error that existed in previous work.…”