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Method using disposable and permanent films for diffusion and implant doping

  • US 6,506,653 B1
  • Filed: 03/13/2000
  • Issued: 01/14/2003
  • Est. Priority Date: 03/13/2000
  • Status: Expired due to Fees
First Claim
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1. A method for making a transistor on a substrate of a semiconductor wafer, the method comprising the steps of:

  • a) forming a gate oxide over the substrate;

    b) forming at least one gate layer over the gate oxide;

    c) patterning the at least one gate layer and the gate oxide to create a gate, the patterning creating two exposed substrate regions on opposing sides of the gate;

    d) forming and patterning a conforming layer to form decomposable sidewall spacers on sidewalls of the gate;

    e) implanting exposed portions of the semiconductor wafer with a dopant of a first type to implant source/drain regions in the substrate;

    f) heating the substrate sufficiently to anneal and activate the dopant to further form the source/drain regions;

    g) removing the decomposable sidewall spacers;

    h) forming a second conforming layer over the gate and source/drain regions;

    i) doping the second conforming layer with a dopant of the first type;

    j) beating the substrate at a temperature high enough to cause diffusion of the dopant of the first type from the conforming layer and into underlying layers, thereby creating extensions in the source/drain regions; and

    k) removing at least a portion of the second conforming layer to expose at least the source/drain regions; and

    wherein the step of doping the second conforming layer with a dopant of the first type comprises the step of implanting the second conforming layer with a dopant of the first type having an energy, wherein a higher dopant energy is chosen with a thicker second conforming layer and a lower dopant energy is chosen with a thinner second conforming layer, the step of implanting performed wherein the dopant impinges a surface of he semiconductor at angles ranging between 45 and 60 degrees.

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