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Manufacturing method of semiconductor device

  • US 8,207,025 B2
  • Filed: 04/01/2011
  • Issued: 06/26/2012
  • Est. Priority Date: 04/09/2010
  • Status: Active Grant
First Claim
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1. A manufacturing method of a semiconductor device comprising the steps of:

  • forming a first insulating film over a surface;

    forming a first mask over the first insulating film;

    performing a slimming process on the first mask, so that a second mask is formed;

    performing an etching process on the first insulating film using the second mask, so that a second insulating film is formed;

    forming a first conductive film over the second insulating film;

    performing a polishing process on the first conductive film and the second insulating film, so that a second conductive film and a third insulating film having equal thicknesses are formed;

    etching the second conductive film, so that a source electrode and a drain electrode which are thinner than the second conductive film are formed;

    forming an oxide semiconductor film in contact with the third insulating film, the source electrode, and the drain electrode;

    forming a gate insulating film over the oxide semiconductor film; and

    forming a gate electrode in a region which is over the gate insulating film and overlaps with the third insulating film.

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