Thermal Budget for Fabricating p+ Polysilicon Gate with Thin Gate Oxide

Abstract

We found that B diffusion profiles in polysilicon can be regarded as having a constant surface concentration, . Using this finding, we derived a B diffusion profile model and identified the diffusion coefficient of B in polysilicon. We also derived the model for the critical time, , to flatten the B profile in a polysilicon gate. Using the critical time for B penetration through the gate oxide, , we determined the allowable diffusion time . We showed that B implantation provides a thermal budget wide enough to fabricate p+ polysilicon gates for 0.1 μm complementary metal oxide semiconductor with pure .