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Semiconductor device and method for manufacturing the same

  • US 9,029,191 B2
  • Filed: 09/23/2010
  • Issued: 05/12/2015
  • Est. Priority Date: 09/24/2009
  • Status: Active Grant
First Claim
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1. A method for manufacturing a semiconductor device, comprising the steps of:

  • forming a gate electrode layer over a substrate having an insulating surface;

    forming a gate insulating layer over the gate electrode layer;

    forming an In—

    Ga—

    Zn—

    O-based oxide semiconductor layer over the gate insulating layer;

    performing a first heat treatment after the oxide semiconductor layer is formed;

    forming source and drain electrode layers over the oxide semiconductor layer after performing the first heat treatment;

    forming an inorganic insulating layer in contact with part of the oxide semiconductor layer, over the gate insulating layer, the oxide semiconductor layer, and the source and drain electrode layers;

    performing a second heat treatment after the inorganic insulating layer is formed; and

    forming a planarization layer comprising a resin material over the inorganic insulating layer,wherein an amount of change in threshold voltage according to a BT test applied to a transistor including the oxide semiconductor layer is less than or equal to 2 V,wherein the BT test is performed under conditions in which a temperature of the substrate is 150°

    C., an electrical field applied to the gate insulating layer is 2 MV/cm, and a time of application of the electrical field is one hour,wherein the second heat treatment is performed at a temperature higher than or equal to 100°

    C. and lower than a maximum temperature in the first heat treatment, andwherein the oxide semiconductor layer is at least partially microcrystalline.

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