Method for forming shallow trench isolation in semiconductor device
View Patent ↗A method for forming shallow trench isolation in a semiconductor device. The method includes forming a pad oxide and a pad nitride on a semiconductor substrate in successive order, forming a trench in the substrate by etching the pad nitride, the pad oxide and the substrate, removing a portion of the pad oxide to expose top corners of the trench, and rounding the exposed portion of the top corners of the trench by a wet chemical etch.
1. A method for forming shallow trench isolation in a semiconductor device, comprising the steps of:
(a) forming a pad oxide and a pad nitride on a semiconductor substrate in successive order;
(b) forming a photoresist pattern on the pad nitride by a photolithography process;
(c) forming a trench in the substrate by etching the pad nitride, the pad oxide and the substrate using the photoresist pattern as an etching mask, and removing the photoresist pattern;
(d) removing a portion of the pad oxide to expose top corners of the trench by selectively wet etching the pad oxide using the pad nitride as an etching mask; and
(e) rounding the exposed portion of the top corners of the trench by a wet chemical etch process using standard cleaning 1 (SC-1) solution without an oxidizing process, wherein
an entirety of a lateral edge of the pad nitride layer defined along the trench has a sharp profile.
2. The method of claim 1 , wherein step (d) is performed by a wet etch process using hydrofluoric acid.
3. The method of claim 1 , wherein the wet etch process using SC-1 solution is performed at a temperature of from 60° C. to 85° C.
4. The method of claim 1 , wherein step (d) is performed without etching of the pad nitride layer.