| 摘要 |
A method for forming a trench for a shallow trench isolation structure wherein the trench has rounded bottom corners. In one embodiment, the present invention performs a breakthrough etch to remove a native oxide layer disposed over a region of a semiconductor substrate. In so doing, a region of the semiconductor substrate is exposed. Next, the present embodiment etches a trench into the semiconductor substrate using a first etching environment. In this embodiment, the first etching environment is comprised of chlorine, hydrogen bromide, helium, and oxygen. The present embodiment then rounds the bottom corners of the trench using a second etching environment. In this embodiment, the second etching environment is comprised sulfur hexafluoride (SF6) and chlorine. In so doing, the present embodiment provides a method for forming a trench for a shallow trench isolation structure wherein the trench does not have sharp bottom corners formed therein.
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