| 摘要 |
Chlorine is incorporated into pad oxide ( 110 ) formed on a silicon substrate ( 120 ) before the etch of substrate isolation trenches ( 134 ). The chlorine enhances the rounding of the top corners ( 140 C) of the trenches when a silicon oxide liner ( 150.1 ) is thermally grown on the trench surfaces. A second silicon oxide liner ( 150.2 ) incorporating chlorine is deposited by CVD over the first liner ( 150.1 ), and then a third liner ( 150.3 ) is thermally grown. The chlorine concentration in the second liner ( 150.2 ) and the thickness of the three liners ( 150.1, 150.2, 150.3 ) are controlled to improve the corner rounding without consuming too much of the active areas ( 140 ).
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