ACCUGLASS 104 was characterized for four micron via etching. The quality of the Spin On Glass (SOG) layer was improved by increasing the cure temperature to 600 degrees c for one hour. A buffered hydrofloric acid diluted 100:1 produced an etch rate of 2700 Angstroms per minute. A plasma etching process was design with a gas mixture of CHF3/CF4/02 in a ratio of 10:3:1.5 wit a regal 700 plasma etcher. The SOG etch rate of this mixture was 600 Angstroms per minute. The selectivity of this plasma for SOG to poly silicon was 12:1. The wet process produced better image profiles for thick glass layers, while the plasma process etch rate is better suited for thin layers.
"Spin on Glass Etch Processing for the RIT NMOS Process,"
Journal of the Microelectronic Engineering Conference: Vol. 4
, Article 33.
Available at: http://scholarworks.rit.edu/ritamec/vol4/iss1/33