(RIE) Plasma process for making metal-semiconductor ohmic type contacts

Claim 1

A process for exposing semiconductor material for the deposition thereon of a layer of a material showing metallic conduction for providing for ohmic type metal-semiconductor contacts which comprises a RIE plasma attack treatment for the formation of apertures in a layer of dielectric material covering the surface of a single crystal semiconductor material, corresponding to areas defined on the surface of said layer of a dielectric by masking, for exposing said underlying single crystal semiconductor material corresponding to said areas in preparation for depositing on said wafer a layer of a material showing metallic conduction for establishing metal-semiconductor contacts corresponding to said areas, wherein (a) said RIE plasma attack utilizes a plasma in a reaction zone containing at least a polymerizable compound containing fluorine and oxygen, and is carried out on the layer of dielectric material until a depth short of exposing the underlying single crystal semiconductor material is achieved and then said RIE plasma attack is interrupted; (b) purging the plasma gases of the preceding RIE plasma attack step in said reaction zone and introducing to said reaction zone a gas mixture of a non-polymerizable, hydrogen-free compound containing fluorine and oxygen while maintaining the atmosphere in said reaction zone free of hydrogen and free of polymerizing compounds; (c) resuming and continuing to complete the RIE plasma attack of the residual layer of dielectric material to thereby expose the single crystal semiconductor material.