Silicate glass

Silicate glasses have been commonly used in the field of semiconductor device fabrication as an insulator between active layers of the semiconductor device. 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 borophosphate silicate glass (BPSG), and the boron and/or phosphorous impurity levels used can be adjusted to affect the silicate glass's melting point.