Method and apparatus for increasing deposition quality of a chemical

Abstract

A method is introduced which improves gas flow characteristics within a reaction chamber used in a Chemical Vapor Deposition (CVD) system, thereby reducing the formation of Light Point Defects (LPDs) and improving epitaxial layer thickness control. This is accomplished by forcing the gas flow from its normally turbulent or non-uniform state into a more steady, linear, and controlled flow using one or more baffles. A steady flow of reactant gases significantly reduces the tendency of particles to move from a lower portion of the reaction chamber and settle onto the wafer during processing, thus reducing LPDs. It further allows a more controlled deposition onto the wafer which in effect improves the layer thickness control. A chemical vapor deposition system is also provided for deposition of silicon from a gas flow onto a substrate which has a reaction chamber with a non-uniform cross-sectional area and one or more baffles placed within the reaction chamber for transforming the non-uniform cross-sectional area into a substantially uniform cross-sectional area. The baffle(s) are placed within the reaction chamber such that their inner surfaces control the gas flow and substantially prevent gas flow turbulence thereby improving uniformity of deposition and reducing or preventing LPDs. Baffles are disclosed which serve the above-mentioned purposes.