Vanguard International Semiconductor Corporation

Shun-Min Yeh

Chyei-Jer Hsieh

Teng-Shao Su

Ching-Yun Chu

An etching back process to improve topographic planarization of a polysilicon layer. First, a polysilicon layer is formed to fill a contact hole between two adjacent insulating structures and cover the entire surface of a semiconductor substrate to a predetermined height, in which a sunken portion is formed in the polysilicon layer over the contact hole. Then, a bottom antireflective coating (BARC) layer is formed to fill the sunken portion and cover the entire surface of the polysilicon layer. Next, in a first etching step, the BARC layer outside the sunken portion of the polysilicon layer is removed and the BARC layer in the sunken portion of the polysilicon layer is retained to flatten the bottom of the sunken portion. Thereafter, in a second etching step, the etching rate of the polysilicon is decreased and the etching rate of the BARC layer is increased to remove a part of the polysilicon layer outside the sunken portion and retain some of the BARC layer inside the sunken portion, in which the BARC layer remaining in the sunken portion protrudes from the polysilicon layer. Next, the polysilicon layer outside the contact hole is completely removed.

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Zhanghua, Taiwan

Shun-Min Yeh