Macronix International Co., Ltd.

Shiuh-Sheng Yu

Chun-Hung Lee

Ming-Chung Liang

Chia-Chi Chung

A method for pulling back SiN to increase rounding effect in a shallow trench isolation process, includes the steps of preparing a substrate of Si and forming a SiO layer on the substrate, forming a Si N layer on the SiO layer, defining Si N trenches by plasma etching, etching the remaining Si N with SF /HB gas, etching SiO layer to form a platform and enhance the rounding of the platform, etching the substrate to have a third shallow trench and a reinforced platform, filling the third shallow trench with oxide, planarizing the filled oxide using chemical mechanical polishing, and removing the Si N layer, wherein after the removal of the Si N layer, multiple cleaning processes are performed.

Method of rounding a topcorner of trench

First of all, a semiconductor substrate that has a pad oxide layer thereon is provided. Then a nitride layer is formed on the pad oxide layer. Next, a photoresist layer is formed and defined on the nitride layer. Afterward, performing a residual etching process to etch the nitride layer to form an opening and a convex remainder of the nitride layer. The convex remainder of the nitride layer and the semiconductor substrate are then etched by way of using a top rounding process to form the rounding corners on the semiconductor substrate. Subsequently, performing a process for forming the trench to form a trench with the rounding corners. Finally, the follow-up processes are performed to form the shallow trench isolation.

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Chi-Lung, Taiwan

Shiuh-Sheng Yu