Effect of rapid thermal annealing on oxide precipitation behavior in silicon crystal

Oxide precipitation behavior after rapid thermal annealing (RTA) in Ar, N-2 or O-2 ambient was investigated. Lightly boron-, nitrogen- or carbon-doped p-CZ silicon wafers with a diameter of 200 mm ([O-1] = 11.5-13.9 x 10(17) atoms/cm(3) (old ASTM)) were prepared as samples. RTA temperature and cooling rate were changed between 1280 and 1200degreesC. and between 70 and 5degreesC/s, respectively. From the result of in Ar ambient, it was found that (1) M-like depth profile of precipitate density was observed in the lightly boron-doped wafer, (2) width of precipitate denuded zone (DZ) was decreased in the nitrogen-doped wafer compared with the lightly boron-doped wafer and (3) DZ width in the carbon-doped wafer was comparable to lightly boron-doped wafer. From the calculated result of the depth profile of vacancy (V) and silicon interstitial (I) concentrations, C-V and C-I, it was clarified that the relationships of thermal equilibrium concentration and the diffusion constant of point defects are to be C-V > C-I and D-V < D-I, respectively. to appear the M-like profile in lightly boron-doped wafer. From the result of the decrease of the DZ width it was deduced that the diffusion constant of vacancy decreased in the nitrogen-doped wafer. From the result of in lightly boron-doped wafer in N-2 or O2 ambient, it was found that (1) the precipitate density was higher compared with that in At ambient and (2) the precipitate was not observed in O-2 ambient, These results due to the injection of the vacancy or the interstitial silicon during RTA in N-2 or O-2, respectively. (C) 2002 Elsevier Science B.V. All rights reserved.