| CPC H01L 21/687 (2013.01) [H01L 21/67253 (2013.01); H01L 21/6838 (2013.01)] | 20 Claims |

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1. A method for processing wafer, comprising:
extracting a first gas from a chamber via a first route;
blocking a second route used to be pumped down to chuck a wafer placed in the chamber, wherein the second route connects the chamber and the first route, and the wafer is positioned adjacent to a first end of the second route; and
providing a second gas via a third route to purge a junction of the first route and a second end of the second route when the second route is blocked, wherein the second end is opposite the first end, and a junction of the third route and the second route is adjacent to the second end of the second route.
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