Selective isotropic etching of SiO over SiN using NF/H remote plasma and methanol vapor.

In this study, an isotropic etching process of SiO selective to SiN using NF/H/methanol chemistry was investigated. HF was formed using a NF/H remote plasma, and in order to remove the F radicals, which induces spontaneous etching of Si-base material, methanol was injected outside the plasma discharge region. Through this process, etch products were formed on the surface of SiO, and then the (NH)SiF was removed by following heating process.