Method for preventing deposition of film on edge or backside of semiconductor wafer in chemical vapor deposition process

摘要

A platen supports a substrate on an interior platen region during the deposition of materials such as tungsten, metal nitrides, other metals, and silicides in a chemical vapor deposition ("CVD") reactor. A deposition control gas composed of a suitable inert gas such as argon or a mixture of inert and reactive gases such as argon and hydrogen is introduced into the CVD reactor. Deposition control gas is preferably introduced through a restrictive opening in a gas orifice surrounding the platen interior region and exits near an edge of the substrate. The restrictive opening accommodates a uniform deposition control gas flow proximate to an edge of the substrate at a pressure greater than reactor pressure near the substrate edge. The deposition control gas substantially prevents process gas access to the substrate edge and backside. In one embodiment, the restrictive opening is formed by placing a restrictive insert within a gas groove surrounding the platen interior region. In another embodiment, the restrictive opening is formed by an exclusion guard substantially uniformly spaced from the edge of the substrate.