Characterize poly etching process to polysilicon film deposition on OD pits defect

The correlation between amorphous polysilicon film and OD (active area) pits that appeared after poly gate etching was investigated in this paper. Some film deposition splits and poly gate etching recipe tests were done to study the OD pit formation mechanism. It is believed that OD pits are induced by amorphous polysilicon bump (haze). We observed the oxidation level of polysilicon film surface could affect OD pits window. To solve OD pits problem, we can increase poly gate recipe organic BARC over etching time or shorten etching recipe breakthrough time. Besides, an extra oxidation step applied before poly gate photo can reduce OD pits tremendously.