Plasma-enhanced CVD of high quality insulating films

A modified plasma-enhanced chemical vapor deposition process (He-PECVD) is described, and used to deposit high quality silicon-based insulators at low substrate temperature (≤ 350°C). This process utilizes very high levels of helium dilution of the reactive gases to eliminate many of the problems normally associated with plasma deposition. SiO2 films deposited by He-PECVD approach the standards of high quality thermally grown oxide and very thin films (≤ 100 Å) with excellent electrical integrity can be deposited over large areas routinely. MOSFET's incorporating deposited gate oxides highlight the fundamental difference between deposition and growth by revealing a strong correlation between the ultimate device performance and pre-deposition silicon surface treatment. By minimizing the extent of process-induced surface damage, good quality deposited oxide FET's can be fabricated without the need for additional high temperature annealing. The He-PECVD process can also be applied to the deposition of Si3N4 films, also with marked improvements in film quality. © 1989.