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Semiconductor device and method for manufacturing the same

  • US 8,809,154 B2
  • Filed: 12/20/2012
  • Issued: 08/19/2014
  • Est. Priority Date: 12/27/2011
  • Status: Active Grant
First Claim
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1. A method for manufacturing a semiconductor device, the method comprising the steps of:

  • forming a gate electrode layer over a substrate;

    forming a first gate insulating film over the gate electrode layer;

    forming a second gate insulating film over the first gate insulating film;

    performing a first heat treatment at a temperature higher than or equal to 450°

    C. after the formation of the second gate insulating film;

    forming an oxide semiconductor film over the second gate insulating film after the first heat treatment; and

    performing a second heat treatment after the formation of the oxide semiconductor film,wherein the first gate insulating film is formed by a plasma CVD method using a first RF power, a silane gas, a nitrogen gas, and an ammonia gas,wherein the second gate insulating film is formed by a plasma CVD method using a second RF power, a silane gas and a nitrogen dioxide gas, andwherein the first RF power is higher than the second RF power.

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