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US4536947A Expired / Lapsed US ⏱️ 0.0 years remaining

CMOS process for fabricating integrated circuits, particularly dynamic memory cells with storage capacitors

Assignee: Intel Corp
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Filing: 1984-07-02
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Granted: 1985-08-27
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Expires: 2004-07-02
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Abstract

Abstract A CMOS process is described which is particularly suited for forming dynamic memory cells. The cells are formed in an n-well and a single plate member formed from a first layer of polysilicon is used for the entire array. Unique etching of the first polysilicon layer prevents stringers from occurring when the second layer of polysilicon is deposited. A tri-layer dielectric is used for the capacitors in the array. Novel "rear-end" processing is disclosed using a phosphorus doped glass.

Inventors

  • 👤 Mark T. Bohr
  • 👤 Ken K. Yu
  • 👤 Leo D. Yau
  • 👤 Shyam G. Garg

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-28 04:59
CPC Classifications
H; H10; H10B; H10B12/00; H10B12/01; H10B12/02; H10B12/03; H10D; H10D84/00; H10D84/01; H10D84/0123; H10D84/0126; H10D84/0165; H10D84/02; H10D84/03; H10D84/038; Y; Y10; Y10S; Y10S148/00; Y10S148/014; Y10S148/043; Y10S148/051; Y10S148/106; Y10S148/117; Y10S438/00; Y10S438/911

Claims Analysis

Total Claims: 7
Claim 1
Independent Claim 175 words
A process for fabricating complementary metal-oxide-semiconductor dynamic memory comprising the steps of: forming a well of a first conductivity type in an epitaxial layer; forming an oxide layer of a first thickness on said epitaxial layer; forming field oxide regions on said oxide layer to a second thickness; defining first regions in said well for capacitors by performing a wet etch to remove said oxide layer in said first region and reduce said field oxide regions in said first region to a third thickness; non-implanting said defined first regions with a dopant of a second conductivity type; forming an insulative layer at least over said defined first regions; forming a first polysilicon layer over said well, said first polysilicon layer being used to form a portion of said capacitor; forming openings in said first polysilicon layer to define second regions for field effect transistors which are coupled to said capacitors; forming word lines from a second layer of polysilicon; whereby memory cells are fabricated in said well and the area for capacitor formation is increased.
Claim 2
Dependent Claim 175 words
A process for fabricating complementary metal-oxide-semiconductor dynamic memory comprising the steps of: forming a well of a first conductivity type in an epitaxial layer; forming an oxide layer of a first thickness on said epitaxial layer; forming field oxide regions on said oxide layer to a second thickness; defining first regions in said well for capacitors by performing a wet etch to remove said oxide layer in said first region and reduce said field oxide regions in said first region to a third thickness; non-implanting said defined first regions with a dopant of a second conductivity type; forming an insulative layer at least over said defined first regions; forming a first polysilicon layer over said well, said first polysilicon layer being used to form a portion of said capacitor; forming openings in said first polysilicon layer to define second regions for field effect transistors which are coupled to said capacitors; forming word lines from a second layer of polysilicon; whereby memory cells are fabricated in said well and the area for capacitor formation is increased.
Claim 3
Dependent Claim 23 words
The process defined by Claim 1 wherein said information of said insulative layer comprises the formation of silicon dioxide and silicon nitride layers.
Claim 4
Dependent Claim 156 words
The process defined by Claim 1 wherein said step of forming openings in said first polysilicon layer comprises the steps of: growing a silicon dioxide layer on the upper surface of said first polysilicon layer; forming a second silicon dioxide layer over said grown silicon dioxide layer by using a chemical vapor deposition step; forming a photoresist layer over said second silicon dioxide layer; defining patterns in said photoresist layer; etching said second silicon dioxide layer employing a wet etchant such that said second silicon dioxide layer is undercut under said photoresist layer; etching said grown silicon dioxide layer in alignment with said photoresist layer employing an anisotropic plasma etching step; etching said first polysilicon layer employing a wet etachant such that undercutting of said polysilicon layer occurs beneath said grown silicon dioxide layer; removing portions of said grown silicon dioxide layer which extend from between said first polysilicon layer and said second silicon dioxide layer.
Claim 5
Dependent Claim 18 words
The process defined in claim 3 wherein said first polysilicon layer forms a continuous plate for said capacitors.
Claim 6
Dependent Claim 24 words
The process defined by claim 1 including an initial step of forming said epitaxial layer doped with a dopant of said second conductivity type.
Claim 7
Dependent Claim 14 words
The process defined in claim 5 wherein said first conductivity type dopant is n-type.

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1988-08-26 1989-02-25 1989-08-27 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1992-08-26 1993-02-25 1993-08-27 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1996-08-26 1997-02-25 1997-08-27 $7700.00 Window Closed / Lapsed

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