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Semiconductor memory device having improved connecting structure of bit line and memory cell

  • US 4,953,125 A
  • Filed: 03/25/1988
  • Issued: 08/28/1990
  • Est. Priority Date: 03/25/1987
  • Status: Expired due to Term
First Claim
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1. A semiconductor device comprising:

  • a semiconductor substrate comprising a first layer of a first conductivity type having a predetermined impurity concentration, a first insulating layer formed on said first layer of the first conductivity type and a second layer of the first conductivity type having a major surface formed on said first insulating layer,said semiconductor substrate having a trench formed through said first layer of the first conductivity type, said first insulating layer and said second layer of the first conductivity type,a first layer of a second conductivity type formed in a region of said second layer of the first conductivity type and in the sidewall portion of said trench,a second layer of the second conductivity type formed spaced apart, by predetermined spacing, from said first layer of the second conductivity type in said second layer of the first conductivity type,a first conductive layer formed adjacent to said second layer of the second conductivity type in said second layer of the first conductivity type,a third layer of the second conductivity type formed on the sidewall of said trench at least on the side of a portion in which said first layer of the second conductivity type is formed,a second insulating layer formed on the sidewall and in the bottom portion of said trench having said third layer of the second conductivity type formed,a second conductive layer formed on the surface of said third insulating layer on the sidewall and the bottom surface of said trench,said third layer of the second conductivity type, said second insulating layer and said second conductive layer constituting a capacitor of a memory cell,a third insulating layer formed in the upper portion of said trench on said major surface, anda third conductive layer formed on said third insulating layer,said second layer of the first conductivity type, said first layer of the second conductivity type, said second layer of the second conductivity type and said third conductive layer constituting a semiconductor element.

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