United Microelectronics Corp.

Paul Hwang

Bruce Han

Eddy Wu

Colin Chung

An inside tube whose wall has oxide layer of impurities is provided, wherein the oxide layer is about 400K &angst;. The inside tube is washed with pure water by level-style washing. Then, taking the inside tube out and soaking it with hydrofluoric acid (HF). Next, the inside tube is taken out from hydrofluoric acid (HF) and it is soaked with pure water. It is dried with ammonia gas(NH,)after the inside tube is taken out from pure water. The inside tube is then washed with pure water by vertical-style washing, and it is dried with nitrogen gas (N,). Finally, the purged inside tube is set into furnace, then proceed a baking process about two hours at low temperature and low pressure to eliminate entirely remained acid from the inside tube, wherein the foregoing temperature range is about between 120&deg; C. to 400&deg; C. and the foregoing pressure is about 0.3 torr. The baking process begins proceeding to follow the purged process has been finished.

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Hsin-Chu, Taiwan

Paul Hwang