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Semiconductor memory device and manufacturing method thereof

  • US 10,510,758 B2
  • Filed: 10/04/2017
  • Issued: 12/17/2019
  • Est. Priority Date: 10/04/2017
  • Status: Active Grant
First Claim
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1. A manufacturing method of a semiconductor memory device, comprising:

  • forming a gate structure on a semiconductor substrate, wherein the gate structure comprises;

    a floating gate electrode;

    a control gate electrode disposed on the floating gate electrode;

    a first oxide layer disposed between the floating gate electrode and the semiconductor substrate; and

    a second oxide layer disposed between the floating gate electrode and the control gate electrode;

    forming an oxide spacer layer conformally on the gate structure and the semiconductor substrate;

    forming a nitride spacer on the oxide spacer layer and on a sidewall of the gate structure; and

    performing an oxidation process after the step of forming the nitride spacer, wherein a thickness of an edge portion of the first oxide layer is increased by the oxidation process, and a thickness of an edge portion of the second oxide layer before the oxidation process is equal to the thickness of the edge portion of the second oxide layer after the oxidation process, wherein the oxide spacer layer directly contacts a topmost surface of the control gate electrode during the oxidation process.

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