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By low-temperature melting technology can be successfully closed a Silicon Dioxide content measured by this technique, Shandong Province, geophysical and geochemical rock Exploration Institute Test Center developed recently obtained national patent.

It is understood that the Silicon Dioxide rocks and minerals encountered in their daily work, there are a dozen ingredients hornblende, zircon and so on. Currently silicate analysis of silica, mostly using hydrochloric acid twice dehydration gravimetric method, polyethylene oxide weight cohesion and traditional gravimetric method, potassium fluosilicate volumetric method and other animal glue cohesion, these methods are not only processes complex, labor-intensive and dangerous temperatures, high production costs.(Source: China Nonferrous network)

This invention relates to a process for selectively etching a silicon dioxide layer deposited on a silicon nitride layer, and more particularly to a process for effectively and efficiently etching such silicon dioxide layer at a high etch rate and high selectivity of silicon dioxide with respect to silicon nitride, particularly in a multilayer structure. The process used to perform this etch must have three basic properties, namely, (1) a high outer layer etch rate which (2) produces substantially upright sidewalls and (3) has a high selectivity of the outer layer being etched down to the etch stop layer. The preferred etch stop material is silicon nitride because it's properties are well known and it is currently used for semiconductor fabrication. The preferred outer layer is silicon dioxide.


 

 

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