Method for forming semiconductor contacts by electroless plating
First Claim
1. A method for forming contacts on semiconductors, comprising:
- applying a reducible cation bearing compound to a surface of the semiconductor;
reducing the compound independent of the surface in an oxygen free ambient;
reacting the cation reduced from the compound with the semiconductor surface to activate the surface for electroless plating; and
electrolessly plating the activated surface with a further metal.
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Accused Products
Abstract
Semiconductor device structures having very smooth surfaces and very high doping levels of opposite types present on the same wafer may be plated in the same electroless plating bath without differentiation between the N and P regions or rough and smooth surface regions. This is achieved by a pre-treatment involving coating the wafer surface with a metal salt (e.g., NiCl in glycol and water) and reducing the metal salt in an oxygen free atmosphere (e.g., hydrogen) at a temperature (e.g., >300° C. for Si) sufficient to promote formation of an intermetallic between the reduced metal and the semiconductor substrate. This provides very uniform and effective nucleation sites for the subsequent electroless plating process irrespective of the smoothness, doping type and doping density of the semiconductor surface.
101 Citations
20 Claims
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1. A method for forming contacts on semiconductors, comprising:
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applying a reducible cation bearing compound to a surface of the semiconductor; reducing the compound independent of the surface in an oxygen free ambient; reacting the cation reduced from the compound with the semiconductor surface to activate the surface for electroless plating; and electrolessly plating the activated surface with a further metal. - View Dependent Claims (2, 3, 4, 5)
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6. A method for simultaneously forming contacts on semiconductor regions of opposite conductivity type, comprising:
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providing a semiconductor substrate having a first surface region of a first type and a second surface region of a second opposite type and some residual oxide on at least one of the first and second surface regions; coating the first and second regions with a reducible cation bearing compound suitable for surface activation; reducing the compound independent of the surface regions in an oxygen free ambient; reacting the cation reduced from the compound with the first and second regions to activate the surface thereof for electroless plating; and simultaneously electrolessly plating the first and second region with a further metal. - View Dependent Claims (7, 8, 9, 10)
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11. A method for simultaneously forming contacts on semiconductor regions of opposite conductivity type, comprising:
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providing a semiconductor substrate having a first surface region of a first type and a second surface region of a second opposite type, wherein at least one of the regions is heavily doped; coating the first and second surface regions with a material containing a cation suitable for forming a compound with the substrate which can catalyze an electroless plating process thereon and thereafter performing the following steps on the first and second regions at the same time; reducing the compound independent of the first and second surface regions and without reacting with the heavily doped region, in an oxygen free ambient to yield cation; reacting the cation to form a compound with the substrate; and electrolessly plating the compound with a further metal. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification