Abstract: The method for avoiding polysilicon film over etch abnormal includes cleaning a semiconductor substrate. A dielectric layer is formed on the substrate. Subsequently, a first silicon source gas at a first flow rate is next performed injecting into a reaction chamber to form a first polysilicon film over the dielectric layer. Successively, a second silicon source gas at a second flow rate is performed injecting into the reaction chamber to form a second polysilicon film over the first polysilicon film, wherein the second silicon source gas having a different growth rate than the first silicon source gas. A patterned photoresist layer is then formed on the second polysilicon film. After the patterned photoresist layer is formed, a dry etching process by way of using the patterned photoresist layer as a etching mask is performed to etch through in turn the second polysilicon film and the first polysilicon film till exposing to the dielectric layer. Finally, the photoresist layer is removed.

Abstract: The method for avoiding polysilicon film over etch abnormal includes cleaning a semiconductor substrate. A dielectric layer is formed on the substrate. Subsequently, a first silicon source gas at a first flow rate is next performed injecting into a reaction chamber to form a first polysilicon film over the dielectric layer. Successively, a second silicon source gas at a second flow rate is performed injecting into the reaction chamber to form a second polysilicon film over the first polysilicon film, wherein the second silicon source gas having a different growth rate than the first silicon source gas. A patterned photoresist layer is then formed on the second polysilicon film. After the patterned photoresist layer is formed, a dry etching process by way of using the patterned photoresist layer as a etching mask is performed to etch through in turn the second polysilicon film and the first polysilicon film till exposing to the dielectric layer. Finally, the photoresist layer is removed.

Abstract: An inside tube whose wall has oxide layer of impurities is provided, wherein the oxide layer is about 400K Å. 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(NH3)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 (N2). 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° C. to 400° C. and the foregoing pressure is about 0.3 torr. The baking process begins proceeding to follow the purged process has been finished.