A study was made of the behavior of dislocations at oxide precipitates in (001) Czochralski Si wafers for various oxide-precipitate sizes (100 to 600nm), densities (108 to 1011/cm3) and background O concentrations (7.7 x 1017 to 1.035 x 1018/cm3) using a bending technique with annular knife edges causing a biaxial stress distribution in the samples. The main advantage of the method used was the possibility of detecting single slip events that may be caused by precipitates with special properties. It was found that the stress level at which dislocation movement could be detected around precipitates depended mainly upon the mean-precipitate diameter. The stress threshold at which dislocations began to move could be increased by heat-treatment prior to application of an external stress. This was attributed to the diffusion of O to the dislocations causing a locking effect and showed that the dislocations were associated with the oxide precipitates prior to any external stress being applied. It was shown that such heat treatments could lead to a mechanical strengthening of the wafers in certain circumstances.

Onset of Slip in Silicon Containing Oxide Precipitates. K.Jurkschat, S.Senkader, P.R.Wilshaw, D.Gambaro, R.J.Falster: Journal of Applied Physics, 2001, 90[7], 3219-25