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Method of making a semiconductor memory circuit device

  • US 5,389,558 A
  • Filed: 08/10/1993
  • Issued: 02/14/1995
  • Est. Priority Date: 11/30/1990
  • Status: Expired due to Term
First Claim
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1. A method for fabricating a semiconductor memory circuit device having an array of memory cells arranged in a matrix form, each memory cell containing a first MISFET and an information storing capacitor connected in series with each other, and also having peripheral circuitry constituted by a plurality of second MISFETs, said method comprising:

  • (a) a step of forming a first gate electrode of each first MISFET and a second gate electrode of each second MISFET in first and second regions, respectively, on a semiconductor substrate;

    (b) after forming the first and second gate electrode, a step of introducing first impurities of N conductivity type into said semiconductor substrate in self-alignment with respect to said first and second gate electrodes in said first and second regions, so as to form a source region and a drain region for said first and second MISFETs;

    (c) after introducing the first impurities of N conductivity type, a step of forming a third insulating film in both said first and second regions on said semiconductor substrate;

    (d) a step of removing a portion of the third insulating film so as to expose one of the source and drain regions of said first MISFET;

    (e) a step of forming a first electrode of said information storing capacitor so as to be in contact with said one of the source and drain regions of said first MISFET exposed through said third insulating film;

    (f) a step of forming in sequence, a dielectric film and a second electrode of said information storing capacitor on said first electrode;

    (g) a step of forming a second insulating film on said third insulating film in the first and second regions of said semiconductor substrate, after performing steps (e) and (f); and

    (h) a step of forming a wiring layer on said second insulating film in said first and second regions, wherein said first and second electrodes extend on said third insulating film in said first region and the thickness of said third insulating film is larger than a total thickness of said first and second electrodes of said information storing capacitor.

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