LATERAL EFFECT OF OXIDATION ON BORON-DIFFUSION IN (100) SILICON

It is found that oxidation of silicon not only enhances the diffusion of the dopants in the regions under oxidized surface but also in the adjacent unoxidized regions. The diffusivity of boron in the narrow unoxidized regions is enhanced by the oxidation with an enhancement decreasing rapidly with the increasing distances from the oxidation regions. The experimental results show that the lateral diffusion length of the oxidation-induced extrinsic point defects that cause this lateral enhancement is 2 μm for temperatures from 900 to 1100°C. This lateral diffusion length is much shorter than the reported vertical diffusion length (25 μm). Nevertheless, for modern integrated circuit dimensions, the lateral effect of oxidation-enhanced diffusion can have significant effects on device properties and minimum pattern spacings.