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Self-aligned edge control in silicon on insulator

  • US 5,863,823 A
  • Filed: 03/21/1995
  • Issued: 01/26/1999
  • Est. Priority Date: 07/12/1993
  • Status: Expired due to Term
First Claim
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1. A method for isolating an active region of a semiconductor layer from another region of the semiconductor layer comprising the steps of:

  • providing a layer of silicon on an insulating substrate;

    forming a pad oxide layer on the layer of silicon;

    providing a layer of silicon nitride on the pad oxide layer;

    providing a photoresist layer over a portion of the layer of silicon nitride such that the photoresist layer is adapted to define the active region in the silicon layer wherein the active region is adapted for forming a transistor;

    removing selected portions of the silicon nitride layer as defined by the photoresist layer;

    removing the photoresist layer to expose a silicon nitride mask that covers portions of the active region;

    oxidizing portions of the silicon layer as allowed by the silicon nitride mask to form a field oxide such that the silicon layer is oxidized at least in part through to the insulating substrate and such that an edge of the active region extends between the field oxide and the insulating substrate; and

    implanting ions of a conductivity determining material in the edge of the active region after the portions of the silicon layer have been oxidized such that the ions are blocked by the silicon nitride mask from the portions of the active region that are covered by the silicon nitride mask and such that the ions are self-aligned in the edge of the active region by the silicon nitride mask.

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