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Method for manufacturing semiconductor device

  • US 10,224,433 B2
  • Filed: 03/23/2017
  • Issued: 03/05/2019
  • Est. Priority Date: 11/30/2011
  • Status: Active Grant
First Claim
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1. A method for manufacturing a semiconductor device comprising the steps of:

  • forming an oxide semiconductor layer over an insulating surface;

    etching a part of the oxide semiconductor layer so that an island-shaped oxide semiconductor layer is formed;

    cleaning a top surface and a side surface of the island-shaped oxide semiconductor layer; and

    forming a source electrode layer and a drain electrode layer over the island-shaped oxide semiconductor layer after the cleaning step,wherein;

    the island-shaped oxide semiconductor layer includes a region in a vicinity of the top surface of the island-shaped oxide semiconductor layer,a concentration of chlorine in the region is lower than or equal to 3.4×

    1017 atoms/cm3 when being measured by secondary ion mass spectrometry after the cleaning step,a concentration of boron in the region is lower than or equal to 4.5×

    1018 atoms/cm3 when being measured by secondary ion mass spectrometry after the cleaning step,a concentration of aluminum in the region is lower than or equal to 7.5×

    1017 atoms/cm3 when being measured by secondary ion mass spectrometry after the cleaning step, anda concentration of fluorine in the region is lower than or equal to 8.9×

    1018 atoms/cm3 when being measured by secondary ion mass spectrometry after the cleaning step.

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