United States Patent 3,539,391
November 10, 1970

Methods Of Coating Semiconductor Materials With Conductive Metals
D.C. Lepiane

Filed September 20, 1966
Image of US PATENT 3,539,391

Abstract of the Disclosure

Before metalizing a silicon base semiconductor slice in an electroless plating bath, glassy phosphosilicate and glassy borosilicate layers that form on opposite sides of the slice during thermal diffusion must be removed. A known method of removing the glassy layers is the immersion of the slice in hydrofluoric acid; however, it is during the removal of the glassy layers that the surface underlying the glassy phosphosilicate is rendered passive for subsequent electroless deposition of a metal. In order to eliminate this passive condition and present an active surface that will receive a uniform and adherene plating of metal, the slice is immersed in a hot aqueous ammonium hydroxide solution after the removal of the glassy and prior to the metal plating
Figure descriptions: cover graphic

  • flow diagram for processes disclosed in this invention.

 Citations [54]:
2,962,394 11/1960 Andres
National Museum of American History
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