| 摘要 |
A method and structure for forming a trench in a semiconductor substrate that includes a semiconductor material such as silicon. The method and structure may be used to form a deep trench or a shallow trench, without having a pad oxide in contact with the semiconductor substrate. The method for forming the deep trench forms a nitride layer on the semiconductor substrate, wherein the selectively etchable layer (e.g., a nitride layer) is selectively etchable with respect to the semiconductor substrate, and wherein there is no pad oxide between the selectively etchable layer and the semiconductor substrate. An erosion resistant layer (e.g., a hard mask oxide layer) is formed on the selectively etchable layer, wherein the erosion resistant layer is resistant to being etched by a reactive ion etch (RIE) process that etches the semiconductor substrate. Then the deep trench is formed by RIE through the erosion resistant layer, through the selectively etchable layer, and into the semiconductor substrate. The method for forming the shallow trench forms a nitride layer on the semiconductor substrate, wherein the selectively etchable layer (e.g., a nitride layer) is selectively etchable with respect to the semiconductor substrate, and wherein there is no pad oxide between the selectively etchable layer and the semiconductor substrate. Then the deep trench is formed by RIE through the selectively etchable layer and into the semiconductor substrate, followed by depositing and planarizing an insulative material in the shallow trench.
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