Die attach using gold ribbon with gold/silicon eutectic alloy cladding

  • US 5,037,778 A
  • Filed: 05/12/1989
  • Issued: 08/06/1991
  • Est. Priority Date: 05/12/1989
  • Status: Expired due to Term
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First Claim
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1. A method for bonding a semiconductor die onto a dielectrically insulated body having a cavity for receiving the die, said cavity having a bottom onto which a layer of gold has been deposited, said die having a silicon chip onto which an intermediate metal barrier layer has been deposited, said method comprising the steps of:

  • (a) preheating the body and gold layer to a temperature of approximately 400°

    C.;

    (b) cutting a strip from a ribbon made of gold and having a gold/silicon eutectic alloy cladding on one side thereof;

    (c) placing said strip into said cavity onto said gold layer such that said cladding is opposed from said gold layer;

    (d) placing said die onto said strip such that said intermediate metal layer is adjacent to said cladding;

    (e) heating said body, strip and die combination to a temperature of approximately 400°

    C.;

    (f) scrubbing said die on said ribbon and cladding at a bonding temperature of approimately 400°

    C. such that said cladding melts and forms a liquid layer which acts as a catalyst for further transfer of thermal energy from said gold ribbon and said gold layer to said die;

    wherein continued scrubbing of said die causes silicon atoms from said chip to penetrate said intermediate barrier metal layer and combine with said gold/silicon liquid layer, thereby increasing the percentage of silicon relative to the percentage of gold in said liquid layer and causing the melting point of said gold/silicon layer to decrease.

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