Nan Ya Technology Corporation

Chih-Chiang Kuo

Chien-Li Cheng

Shian-Hau Liao

Tsung-Shin Wu

A method for forming a stack capacitor includes providing a substrate with a bottom layer, a BPSG layer, a USG layer and a top layer thereon; using the top layer as a hard mask and the substrate as a first etching stop layer to perform a dry etching process to form a tapered trench in the bottom layer, the BPSG layer and the USG layer; removing the top layer to perform a selective wet etching process to partially remove the BPSG layer; depositing conformally a poly-Si layer and filling the trench with a sacrificial layer; removing the poly-Si layer unmasked by the sacrificial layer; using the bottom layer as a second etching stop layer to perform a wet etching process to remove the USG layer and BPSG layer; performing a static drying process; and depositing a dielectric layer and a conductive material to form the stack capacitor.

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Taipei, Taiwan

Chih-Chiang Kuo