Photoelectron-induced selective etch process

  • US 5,129,991 A
  • Filed: 04/30/1991
  • Issued: 07/14/1992
  • Est. Priority Date: 04/30/1991
  • Status: Expired due to Term
First Claim
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1. A process for selectively etching a region on the surface layer of a substrate device which comprises the steps of:

  • (a) providing in a chamber a substrate device having a photon-transparent surface layer, a region of which is to be selectively etched away, said substrate device further having a conductive regions below said surface layer and characterized by a photoemission threshold, said conductive region being adjacent to another substrate device region characterized by a photoemission threshold value greater than the photoemission threshold of said conductive region;

    (b) providing an etch gas to said chamber causing said etch gas to adsorb onto the surface layer of said substrate device, said etch gas being selected to enable the dissociation of said etch gas into fragments which react with the substrate device surface layer to form a volatile reaction product;

    (c) impinging a beam of radiation upon said substrate device within said chamber, said beam radiation wavelength being selected to exceed the photoemission threshold of said substrate device conductive region to thereby generate photo-excited electrons which are reactive with the etch gas molecules adsorbed onto the substrate device surface layer above said conductive regions to form reactive etch fragments, said beam radiation wavelength further being selected to be less than the photoemission threshold of said other substrate device region adjacent said conductive region; and

    ,(d) removing volatile species formed on the substrate device surface above said conductive region by the reaction of the reactive etch fragments and said substrate device surface layer to thereby selectively expose the conductive region of said substrate device lying underneath said surface layer while said other substrate device region adjacent said conducive region remains covered by said photon-transparent surface layer.

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