| 摘要 |
A dry etching method for silicon trench etching in which high anisotropy, high etchrate and low pollution may be achieved simultaneously. A single crystal silicon substrate is etched using a gas mixture of S2Cl2 and S2F2 while a wafer is cooled to about -70 DEG C. Etching proceeds by a mechanism in which a radical reaction by Cl* derived from S2Cl2 and F* derived from S2F2 is assisted by the incident energy of S+, SF+, SCl+ or Cl+ ions. The highly reactive F* radicals of a small atomic radius contribute to increasing the etchrate. Deposition of sulfur yielded from S2Cl2 and S2F2 provides for efficient sidewall protection to achieve high anisotropy. The conventional practice to add fluorine based gases with a view to increasing the etchrate is in need of an excess quantity of a deposition material to give rise to increased pollution by particles. There is no risk of pollution with the sulfur deposit according to the present invention because the sulfur deposit may easily be sublimed off by heating the wafer.
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