Impurity Redistribution in a Semiconductor during Thermal Oxidation

Abstract

A general review of mathematical treatments on this redistribution phenomena has been made and discussed. A series method is developed and exact solutions describing the redistributed impurity concentration profiles in both the oxide and the semiconductor can be given. Boundary conditions of diffusion equations are discussed according to different physical situations. Special cases are treated for three initial impurity concentration profiles in silicon: Gaussian, complementary error function, and uniform. Experiments were performed on boron-doped silicon by wet oxygen at 1200~ The initial concentration profile was a Gaussian, and the segregation coefficient was found to be about 1.8. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.192.114.19 Downloaded on 2015-05-30 to IP A2n "1 (Dlt) (2~-1)/2 i2n-1 erfc 0 | ----0 for all t > 0 2 J [A17] ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.192.114.19 Downloaded on 2015-05-30 to IP

Boron Segregation at Si ‐ SiO2 Interface as a Function of Temperature and Orientation

“…The ion microprobe has been used in this study to determine the boron concentration on both sides of the interface thus providing a direct measure of the segregation coefficient. This avoids dependence on a modeling procedure as required by the above studies (2)(3)(4)(5)(6)(7)(8). Such a technique has been emplo~-ed (10,11) 4x previously.…”

“…However, this phenomenon was never completely understood and further experimentation showed that very small amounts of H2 in the diffusion ambient drastically reduce the masking ability of Mo films against its diffusion. The importance of the enhanced diffusion of B in SiO2 when heated in H2 and H20 ambients (2) has had important consequences for B-doped polysilicon-gate MOSFET's and has been described by others (3)(4)(5)(6). Heat-treatment of St-gate MOSFET's in H2 and H20 ambients has been observed to decrease the p-channel enhancement mode MOSFET threshold or produce p-channel depletion mode devices instead of the desired enhancement mode device.…”