Control of fixed charges at the oxide/Si interface by eliminating the incorporated carbon in bpsg films

摘要

Carbon in BPSG films receives much attention as one of the most important impurities because carbon atoms are incorporated in BPSG films deposited with organic sources. Carbon atoms segregate at the oxide/Si interface and induce fixed positive charges, causing the n-channel field threshold voltage to decrease. High deposition temperatures are preferred in order to lower the carbon concentration in as-deposited BPSG films. However, deposition at high temperatures tends to degrade the uniformity on a wafer. In this paper, it is shown, for the first time, that the incorporated carbon can be eliminated from BPSG films and from the interface by the appropriate annealing process in an oxygen ambient.