Patent ID: 6572924
Filing Date: 2003-06-03
Classification: C23C,C30B

Abstract:
A chemical vapor deposition system comprising:a substrate handling system including a handling chamber; a substrate processing system including a deposition chamber having one or more gas inlets for deposition gas or purge gas, and having an exhaust outlet; a gate valve controlling an opening into the deposition chamber through which a substrate is moved into or out of the deposition chamber from the handling chamber; one or more purge gas inlets and outlets connected to said handling chamber, configured to maintain a pressure balanced fairly closely with the pressure of the deposition chamber, but with the deposition chamber pressure being slightly less than that of the handling chamber when the gate valve is open so that particles in the deposition chamber do not flow into the handling chamber; a first exhaust conductance path connected to said exhaust outlet for conducting exhaust from the deposition chamber when deposition gas is flowing into the deposition chamber; a second exhaust conductance path connected to the exhaust outlet and separated from the first path so that particles from the first path cannot enter the deposition chamber through the second path; at least one exhaust valve connected to control the flow of gas from the exhaust outlet into either of said exhaust paths while the other path is closed, said exhaust valve being positioned to minimize the distance between the exhaust valve and the exhaust outlet to minimize the surfaces exposed to deposition gas before reaching the exhaust valve; a controller set to position said exhaust valve so that exhaust gases are directed to said fist path when deposition gases are being introduced into the deposition chamber through said gas inlet and said deposition gases are being purged front the chamber; and said controller being set to control the deposition chamber purge gas exhaust gas flow so that said at least one exhaust valve is positioned to direct flow into said second exhaust path and to prevent flow into said first path before said gate valve is opened so that if pressure fluctuations occur in the deposition chamber when the gate valve is opened, particles in the first conductance path are blocked from flowing upstream into the deposition chamber.