Abstract: A process and system for preventing gases from either leaking into or out of a thermal processing chamber that is designed to operate at or near atmospheric pressure is disclosed. For instance, in one embodiment, gases are prevented from leaking into a thermal processing chamber by maintaining the pressure within the chamber at levels that are slightly greater than atmospheric pressure. In an alternative embodiment, in order to prevent gases from leaking out of the chamber, the pressure within the chamber is maintained at levels slightly less than atmospheric pressure. During operation of the thermal processing chamber, a gas is continuously circulated through the chamber. In order to carry out the process of the present invention, a pressure control device can be placed upon the gas outlet for maintaining the pressure within the chamber within a desired range.

Abstract: In a method for the formation of an isolating oxide layer on a silicon substrate, an anti-nitridation layer is formed on a silicon substrate at locations where isolating oxide is desired. The anti-nitridation layer has openings therethrough which expose the silicon substrate at locations where isolating oxide is not desired. A thin silicon nitride layer is selectively grown at the locations where isolating oxide is not desired by nitridation of the exposed silicon substrate. Isolating oxide is then selectively grown at the locations where isolating oxide is desired. The thin silicon nitride layer inhibits oxide growth at the locations where isolating oxide is not desired. The method reduces "bird's beak" formation and is particularly applicable to high density IGFET devices.