s*******r 发帖数: 921 | 1 You can try to deposit a layer of Silicon Nitride above the
oxide layer.
Usually, SiN can work as a hard mask for SiO.
Also, it is possible for you to find a good etch recipe
which has a high selectivity of SiN to SiO, say, 3:1. In
this way, the thickness of SiN depends on the selectivity
you finally get - for 3:1, you need at least 9000A SiN. At
such a thich SiN layer, you might need to consider issues
caused by stress of its.
And, it's very easy to strip Nitride by wet-etch - hot
H3PO4.
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