Coating GaSb or GaAs Zincsilicafilm 306 will not wet GaAs orGaSb unless the wafer surfaces have been conditioned prior to application. The wafer conditioning is quite simple. The wafers are heated at 350 o C or 400 o C for a few minutes in air. The wafers are cooled and are then ready for coating. Proper surface conditioning is evidenced when a drop of the Zincsilicafilm 306 mixture is placed on the surface of the wafer and proceeds to wet out over the wafer surface.
Improper conditioning is evidenced when the drop remains stationary with no wetting or spreading.
After conditioning the wafers are ready for coating. The wafers may be coated by spinning, or in the case of odd size or bowed wafers, the solution may be diluted with alcohol and the solution may be applied by painting. For spinning, spin speeds of 2000-3000 rpm or of such magnitude so as to yield a minimum lip on the edge of the wafer may be used. Diffusion Diffusion may be carried out in N 2 or argon. Slight traces of oxygen in the ambient will cause no difficulty.