Silicate glasses are amorphous and have no crystalline structure. [1] Silicate glass is useful for conducting x-ray crystallography because the x-rays will pass through the silicate pipette holding the sample under examination without being reflected by crystals in the glass itself; thus the resulting measurement is assured to be from the sample. Silicate glasses have also been commonly used in the field of semiconductor device fabrication as an insulator between active layers of the semiconductor device. Also, some airbags in cars react SiO2 with harmful byproducts of nitrogen gas producing reactions to produce Silicate glass to remove the harmful substances (K2O and Na2O) .
These materials have relatively low melting temperatures, and can be flowed by heating in order to "planarize" the semiconductor layers. There will typically be contact holes or vias etched into the glass layers using wet etching or dry etching, and the silicate glasses can then be reflowed by heating in order to make smoother tops to the contact holes or vias, which makes the metal connections into the contact holes or vias more durable.
The silicate glasses are typically formed of phosphosilicate glass (PSG) or borophosphosilicate glass (BPSG). The boron and/or phosphorus impurity levels used can be adjusted to affect the silicate glass's melting point.
References
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