Method for fabricating in-situ doped polysilicon employing overdamped gradually increasing gas flow rates with constant flow rate ratio

摘要

A method of fabricating a film of in-situ doped polycrystalline silicon having a surface that is free of microscopic hillocks includes the steps of providing a deposition chamber and a wafer therein on which the film is to be fabricated and introducing one gas containing silicon atoms and another gas containing dopant atoms into said chamber with respective flow rates; wherein the respective flow rates are gradually increased in an overdamped fashion over a start-up time interval of at least one minute from zero to respective steady state values while simultaneously the ratio of the respective flow rates is kept within 25% of the ratio of said steady state values.