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A highly selective dry etching process for the removal of silicon nitride (Si3N4)(Si3N4) layers from silicon and silicon dioxide(SiO2) is described and its mechanism examined. This new process employs a remote O2/N2O2/N2 discharge with much smaller flows of CF4CF4 or NF3NF3 as a fluorine source as compared to conventional Si3N4Si3N4 removal processes. 

Etch rates of Si3N4Si3N4 of more than 30 nm/min were achieved for CF4CF4 as a source of fluorine, while simultaneously the etch rate ratio of Si3N4Si3N4 to polycrystalline silicon was as high as 40, and silicon dioxide(SiO2) was not etched at all. For NF3NF3 as a fluorine source, Si3N4Si3N4 etch rates of 50 nm/min were achieved, while the etch rate ratios to polycrystalline silicon and silicon dioxide(SiO2) were approximately 100 and 70, respectively. In situ ellipsometry shows the formation of an approximately 10-nm-thick reactive layer on top of the polycrystalline silicon. This oxidized reactive layer suppresses etching reactions of the reactive gas phase species with the silicon.

In this paper, by the sol - gel prepared by low thermal conductivity, low density hydrophobic silicon dioxide(SiO2) aerogels, and the sandwich structure formed by its direct application, or to form a coating on the cotton and polyester flakes load, etc. Three ways of holding applied research to develop silicon dioxide(SiO2) aerogels in the clothing, goods were loaded and uses other sectors.


 

 

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