Controlling the amount of Si-OH bonds for the formation of high-quality low-temperature gate oxides for poly-Si TFTS

Lowering process temperatures for polysilicon thin-film-transistors (TFTs) has given rise to new worries about the quality of TFT gate oxides. Specifically, presence of large amounts of Si-OH bonds in gate oxides has become a matter of concern. We discuss methods for suppressing the formation of SI-OH bonds during chemical vapor deposition (CVD) of low-temperature processed (LTP) gate oxides. The use of remote-plasma CVD and control of the reaction between the silicon source gas and the oxygen source gas are both shown to be effective. We also show that decreased amounts of SI-OH bonds in LTP-CVD gate oxides result in desirable decreases in fixed oxide charge densities.