The present invention relates generally to semiconductor manufacturing and, more particularly, to top gas baffle and distributor for delivering gases in semiconductor processing chambers.
Chemical vapor deposition (CVD) is a gas reaction process used in the semiconductor industry to form thin layers or films of desired materials on a substrate. Some high density plasma (HDP) enhanced CVD processes use a reactive chemical gas along with physical ion generation through the use of an RF generated plasma to enhance the film deposition by attraction of the positively charged plasma ions onto a negatively biased substrate surface at angles near the vertical to the surface, or at preferred angles to the surface by directional biasing of the substrate surface. One goal in the fabrication of integrated circuits (ICs) is to form very thin, yet uniform films onto substrates, at a high throughput. Many factors, such as the type and geometry of the power source and geometry, the gas distribution system and related exhaust, substrate heating and cooling, chamber construction, design, and symmetry, composition and temperature control of chamber surfaces, and material build up in the chamber, must be taken into consideration when evaluating a process system as well as a process which is performed by the system.
Uneven gas distribution is one problem encountered in semiconductor fabrication, which affects deposition uniformity. In one known chamber configuration, a gas plenum is provided around the perimeter of a processing region and a plurality of nozzles extend radially inwardly to provide gases to the substrate surface. A challenge in such a design is to evenly distribute gases across the substrate surface so that more gas is not provided towards the edge of the substrate than towards the center of the substrate. A top gas nozzle, positioned directly above the substrate support member, can be used to improve deposition uniformity.
Despite the improvements obtainable by using of a top gas nozzle further improvements and/or alternative techniques are desirable for increasing uniformity of gas distribution on the surface of a substrate.