Grooved gas gate

Abstract

An improved magnetic gas gate is adapted to operatively interconnect two adjacent chambers, in the first chamber of which process gases are introduced for depositing a first layer upon a magnetic substrate and in the second chamber of which process gases are introduced for depositing a second layer atop the first layer. Since it is important to prevent the second chamber gases from contaminating the first chamber gases, a constant pressure differential established between the chambers is employed to provide a substantially unidirectional flow of gases from the first chamber into the second chamber. Magnetic gas gates have been used in the prior art to reduce the size of gas gate passageways by creating a magnetic field which urges the unlayered surface of the substrate toward a wall of the passageway. Although the size of the passageway opening is thereby reduced with a corresponding reduction in back diffusion of gases from the second chamber, the passageway is simultaneously divided into a relatively large flow channel and a relatively narrow flow channel. The present invention reduces the back diffusion of gases through the relatively narrow flow channel by forming a plurality of elongated grooves in the passageway wall toward which the unlayered surface of the substrate is urged. The grooves are substantially coextensive with the length of the passageway so as to operatively interconnect the adjacent chambers. The flow channels thus established are adapted to accommodate a sufficient flow of inert sweep gases to further reduce the back diffusion of process gases through the narrow flow channel.