Reaction chamber for processing semiconductor substrates with gas flow control capability

Apparatus, particularly reaction chamber for processing semiconductor substrate is presented. A reaction chamber with gas exit flow control capability comprises an upper body, a substrate supporting part, a shower head for letting in gas which is used for processing the substrate, a lower body comprising duct, wherein the duct has a multiple of duct holes and a flow control liner configured to surround the duct and the flow control liner has a multiple of flow holes, wherein the duct holes and flow holes are used to control the exit flow of the gas used for substrate processing, and the flow control liner may rotate around so that the duct holes and the flow holes can be overlapped. The duct can have scribe mark for various hole sizes and shapes.