Abstract:
A glass coating is applied to a semi-conductor body by applying a slurry of glass and a photo resist to the surface, exposing and developing to remove the slurry from selected areas and heating to remove the remaining resist and fuse the glass to desired areas of the body. The glass may consist of lead borosilicate glass and the resist of Kmer. The mixture is prepared by grinding the glass with hard alumina balls in polyethylene bottles containing methyl alcohol, filtering off the methyl alcohol, and adding the ground glass to xylene to leach out traces of polyethylene. The xylene is filtered off, and since drying is undesirable a sample is used to determine the proportion of xylene remaining so that the bulk may be brought to a standard xylene level. The resulting paste is mixed in a ball mill with the Kmer photo resist and xylene and applied to the semi-conductor surface by spinning. The mixture is then baked, exposed to the desired light pattern, and material from the unexposed regions removed by development. The coated semi-conductor body is dried and the glass fired in oxygen at 500 DEG C. A layer of silicon oxide may cover the semi-conductor body before the glass is applied. The figure shows a planar diode with the semi-conductor 1 covered by an oxide coating 3 and glass coating 4 applied to leave an opening for contact 5 to the semi-conductor.