Other

Ming-Horng Lin

Ray C Lee

Nien-Yu Tsai

A method to fabricate bottle-shaped deep trench into a semiconductor substrate. After a neck profile is formed, the chlorine gas at a predetermined flow rate is added to the etching plasma gas composition, while the flow rates of the plasma gases are increased by about 30% by volume, to create an enlarged lower portion of the deep trench. Preferably, the neck portion is etched using an etching composition which contains HBr, NF,, and (He/O,) provided at flow rates of about 87:13:35 sccm. The enlarged lower portion is etched using an etching composition which contains HBr, NF,, and (He/O,) provided at flow rates of about 113&plusmn;12:17&plusmn;2:46&plusmn;5 sccm, and Cl,provided at a flow rate between 10 and 40 sccm. It was found that the width of the lower portion of the deep trench can be increased by 100% with minimum side effects such as polymer deposition in the plasma chamber, which could occur as result of substantially increased flow rate of HBr and/or NF,.

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Hsinchu, Taiwan

Ming-Horng Lin