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US5066606A Expired / Lapsed US ⏱️ 0.0 years remaining

Implant method for advanced stacked capacitors

Assignee: Micron Technology Inc
•
Filing: 1990-12-07
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Granted: 1991-11-19
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Expires: 2010-12-07
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Abstract

Abstract An implant method to develop a storage node access MOSFET to a 3-dimensional stacked capacitor storage cell during a semiconductor fabrication process. This implant method utilizes one layer of oxide to serve as both a MOSFET's (N-channel or P-channel) lightly doped drain spacer as well as a subsequent polysilicon etch stopper when etching a FET's digitline. As DRAM density increases the use of only one oxide layer decreases oxide bridging or buildup.

Inventors

  • 👤 Ruojia Lee

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-02 09:15
CPC Classifications
H; H10; H10B; H10B12/00; H10B12/01; H10B12/02; H10B12/05

Claims Analysis

Total Claims: 24
Claim 1
Independent Claim 266 words
A process for developing source/drain diffusion regions of an MOSFET during fabrication of a semiconductor on a silicon substrate, said process steps comprising: a) depositing a first dielectric layer superjacent surface of said silicon substrate; b) depositing a first conductive layer superjacent surface of said first dielectric; c) depositing a second dielectric layer superjacent said first conductive layer; d) masking and etching said first conductive and said second dielectric layers to form a first control line; e) implanting a lightly doped impurity into said silicon substrate, thereby forming said source/drain diffusion regions on opposite sides of said control line; f) said step of implanting a lightly doped impurity causing said control line to bridge said source/drain diffusion regions, thereby forming a gate isolated from said silicon substrate by said first dielectric layer, said gate bridging a pair of said source/drain diffusion regions to form said MOSFET; g) depositing a third dielectric layer superjacent existing topology of surface of said semiconductor; h) creating an aligned d buried contact location thereby providing a second control line junction at a first source/drain diffusion region of said MOSFET; i) depositing a second conductive layer superjacent said semiconductor surface, said second conductive layer making direct contact to said second control line junction at said buried contact location; j) masking and etching said second conductive layer to form a conductive second control line; k) anisotropically etching said third dielectric layer; and l) implanting a heavily doped impurity into said source/drain diffusion regions of said MOSFET, said implanting taking place at regions not covered by an implant blocking remnant of said second dielectric.
Claim 2
Dependent Claim 266 words
A process for developing source/drain diffusion regions of an MOSFET during fabrication of a semiconductor on a silicon substrate, said process steps comprising: a) depositing a first dielectric layer superjacent surface of said silicon substrate; b) depositing a first conductive layer superjacent surface of said first dielectric; c) depositing a second dielectric layer superjacent said first conductive layer; d) masking and etching said first conductive and said second dielectric layers to form a first control line; e) implanting a lightly doped impurity into said silicon substrate, thereby forming said source/drain diffusion regions on opposite sides of said control line; f) said step of implanting a lightly doped impurity causing said control line to bridge said source/drain diffusion regions, thereby forming a gate isolated from said silicon substrate by said first dielectric layer, said gate bridging a pair of said source/drain diffusion regions to form said MOSFET; g) depositing a third dielectric layer superjacent existing topology of surface of said semiconductor; h) creating an aligned d buried contact location thereby providing a second control line junction at a first source/drain diffusion region of said MOSFET; i) depositing a second conductive layer superjacent said semiconductor surface, said second conductive layer making direct contact to said second control line junction at said buried contact location; j) masking and etching said second conductive layer to form a conductive second control line; k) anisotropically etching said third dielectric layer; and l) implanting a heavily doped impurity into said source/drain diffusion regions of said MOSFET, said implanting taking place at regions not covered by an implant blocking remnant of said second dielectric.
Claim 3
Dependent Claim 19 words
A process as recited in claim 1, wherein said first, said second and said third dielectric layers include oxide.
Claim 4
Dependent Claim 20 words
A process as recited in claim 1, wherein said first conductive layer comprises a layer of tungsten silicide and metal.
Claim 5
Dependent Claim 14 words
A process as recited in claim 1, wherein said buried contact is self aligned.
Claim 6
Dependent Claim 15 words
A process as recited in claim 1, wherein said second conductive layer is doped polysilicon.
Claim 7
Dependent Claim 31 words
A process as recited in claim 1, wherein said implanting a lightly doped impurity is from an N- phosphorus source and a heavily doped impurity is from an N+ arsenic source.
Claim 8
Dependent Claim 32 words
A process as recited in claim 1, wherein said implanting a lightly doped impurity is from an P- boron source and a heavily doped impurity is from an P+ boron diflouride source.
Claim 9
Dependent Claim 12 words
A process as recited in claim 1, wherein said MOSET is N-channel.
Claim 10
Dependent Claim 12 words
A process as recited in claim 1, wherein said MOSFET is P-channel.
Claim 11
Dependent Claim 310 words
A process for developing source/drain diffusion regions of storage node MOSFET during fabrication of a DRAM array on a silicon substrate, said process steps comprising: a) depositing a first dielectric layer superjacent surface of said array; b) depositing a first conductive layer superjacent surface of said array; c) depositing a second dielectric layer superjacent said first conductive layer; d) masking and etching said first conductive and said second dielectric layers to form a plurality of parallel conductive wordlines arranged in rows, said wordlines being separated from said silicon substrate by said first dielectric layer; e) implanting a lightly doped impurity into said silicon substrate, thereby forming said source/drain diffusion regions on opposite sides of each said wordline; f) said step of implanting a lightly doped impurity causing said wordlines to bridge said source/drain diffusion regions, thereby forming a gate isolated from said silicon substrate by said first dielectric layer, said gate bridging a pair of said source/drain diffusion regions to form said MOSFET; g) depositing a third dielectric layer superjacent said array surface; h) creating an aligned buried contact location thereby providing a digitline junction at a first source/drain diffusion region of each said MOSFET; i) depositing a second conductive layer superjacent said array surface, said second conductive layer making direct contact to said digitline junctions at said buried contact locations; j) masking and etching said second conductive layer to form a plurality of parallel conductive digitlines arranged in columns such that a digitline maintains electrical contact at each said digitline junction within a said column, said digitlines running perpendicular to and over said wordlines forming a 3-dimensional, waveform-like topology; k) anisotropically etching said third dielectric layer; and l) implanting a heavily doped impurity into said source/drain diffusion regions of each said MOSFET, said implanting taking place in regions not covered by an implant blocking remnant of said second dielectric.
Claim 12
Dependent Claim 310 words
A process for developing source/drain diffusion regions of storage node MOSFET during fabrication of a DRAM array on a silicon substrate, said process steps comprising: a) depositing a first dielectric layer superjacent surface of said array; b) depositing a first conductive layer superjacent surface of said array; c) depositing a second dielectric layer superjacent said first conductive layer; d) masking and etching said first conductive and said second dielectric layers to form a plurality of parallel conductive wordlines arranged in rows, said wordlines being separated from said silicon substrate by said first dielectric layer; e) implanting a lightly doped impurity into said silicon substrate, thereby forming said source/drain diffusion regions on opposite sides of each said wordline; f) said step of implanting a lightly doped impurity causing said wordlines to bridge said source/drain diffusion regions, thereby forming a gate isolated from said silicon substrate by said first dielectric layer, said gate bridging a pair of said source/drain diffusion regions to form said MOSFET; g) depositing a third dielectric layer superjacent said array surface; h) creating an aligned buried contact location thereby providing a digitline junction at a first source/drain diffusion region of each said MOSFET; i) depositing a second conductive layer superjacent said array surface, said second conductive layer making direct contact to said digitline junctions at said buried contact locations; j) masking and etching said second conductive layer to form a plurality of parallel conductive digitlines arranged in columns such that a digitline maintains electrical contact at each said digitline junction within a said column, said digitlines running perpendicular to and over said wordlines forming a 3-dimensional, waveform-like topology; k) anisotropically etching said third dielectric layer; and l) implanting a heavily doped impurity into said source/drain diffusion regions of each said MOSFET, said implanting taking place in regions not covered by an implant blocking remnant of said second dielectric.
Claim 13
Dependent Claim 19 words
A process as recited in claim 10, wherein said first, said second and said third dielectric layers include oxide.
Claim 14
Dependent Claim 20 words
A process as recited in claim 10, wherein said first conductive layer comprises a layer of tungsten silicide and metal.
Claim 15
Dependent Claim 14 words
A process as recited in claim 10, wherein said buried contact is self aligned.
Claim 16
Dependent Claim 15 words
A process as recited in claim 10, wherein said second conductive layer is doped polysilicon.
Claim 17
Dependent Claim 31 words
A process as recited in claim 10, wherein said implanting a lightly doped impurity is from an N- phosphorus source and a heavily doped impurity is from an N+ arsenic source.
Claim 18
Dependent Claim 32 words
A process as recited in claim 10, wherein said implanting a lightly doped impurity is from an P- boron source and a heavily doped impurity is from an P+ boron diflouride source.
Claim 19
Dependent Claim 12 words
A process as recited in claim 10, wherein said MOSET is N-channel.
Claim 20
Dependent Claim 12 words
A process as recited in claim 10, wherein said MOSFET is P-channel.
Claim 21
Dependent Claim 329 words
A process for developing source/drain diffusion regions of storage node access N-channel MOSFET during fabrication of a DRAM array on a silicon substrate, said process steps comprising: a) depositing a first oxide layer superjacent surface of said array; b) depositing a first conductive layer superjacent surface of said array, said conductive layer includes n-type doped polysilicon and tungsten silicide; c) depositing a second oxide layer superjacent said first conductive layer; d) masking and etching said first conductive and said second oxide layers to form a plurality of parallel conductive wordlines arranged in rows, said wordlines being separated from said silicon substrate by said first oxide layer; e) implanting a N- impurity into said silicon substrate, thereby forming lightly doped said source/drain diffusion regions on opposite sides of each said wordline; f) said step of implanting said N- impurity causing said wordlines to bridge said source/drain diffusion regions, thereby forming a gate isolated from said silicon substrate by said first dielectric layer, said gate bridging a pair of said source/drain diffusion regions to form said N-channel MOSFET; g) depositing a third oxide layer superjacent said array surface; h) creating a self aligned buried contact location thereby providing a digitline junction at a first source/drain diffusion region of each said MOSFET; i) depositing a polsilicon layer superjacent said array surface, said polysilicon being doped as n-type conductivity and making direct contact to said digitline junctions at said buried contact locations; j) masking and etching said polysilicon layer to form a plurality of parallel conductive digitlines arranged in columns such that a digitline maintains electrical contact at each s id digitline junction within a said column, said digitlines running perpendicular to and over said wordlines forming a 3-dimensional, waveform-like topology; k) anisotropically etching said third oxide layer; and l) implanting an N+ impurity into said source/drain diffusion regions of each said lightly doped N-channel MOSFET, said implanting taking place in regions not covered by an implant blocking remnant of said second dielectric.
Claim 22
Dependent Claim 329 words
A process for developing source/drain diffusion regions of storage node access N-channel MOSFET during fabrication of a DRAM array on a silicon substrate, said process steps comprising: a) depositing a first oxide layer superjacent surface of said array; b) depositing a first conductive layer superjacent surface of said array, said conductive layer includes n-type doped polysilicon and tungsten silicide; c) depositing a second oxide layer superjacent said first conductive layer; d) masking and etching said first conductive and said second oxide layers to form a plurality of parallel conductive wordlines arranged in rows, said wordlines being separated from said silicon substrate by said first oxide layer; e) implanting a N- impurity into said silicon substrate, thereby forming lightly doped said source/drain diffusion regions on opposite sides of each said wordline; f) said step of implanting said N- impurity causing said wordlines to bridge said source/drain diffusion regions, thereby forming a gate isolated from said silicon substrate by said first dielectric layer, said gate bridging a pair of said source/drain diffusion regions to form said N-channel MOSFET; g) depositing a third oxide layer superjacent said array surface; h) creating a self aligned buried contact location thereby providing a digitline junction at a first source/drain diffusion region of each said MOSFET; i) depositing a polsilicon layer superjacent said array surface, said polysilicon being doped as n-type conductivity and making direct contact to said digitline junctions at said buried contact locations; j) masking and etching said polysilicon layer to form a plurality of parallel conductive digitlines arranged in columns such that a digitline maintains electrical contact at each s id digitline junction within a said column, said digitlines running perpendicular to and over said wordlines forming a 3-dimensional, waveform-like topology; k) anisotropically etching said third oxide layer; and l) implanting an N+ impurity into said source/drain diffusion regions of each said lightly doped N-channel MOSFET, said implanting taking place in regions not covered by an implant blocking remnant of said second dielectric.
Claim 23
Dependent Claim 328 words
A process for developing source/drain diffusion regions of storage node access P-channel MOSFET during fabrication of a DRAM array on a silicon substrate, said process steps comprising: a) depositing a first oxide layer superjacent surface of said array; b) depositing a first conductive layer superjacent surface of said array, said conductive layer includes p-type doped polysilicon and tungsten silicide; c) depositing a second oxide layer superjacent said first conductive layer; d) masking and etching said first conductive and said second oxide layers to form a plurality of parallel conductive wordlines arranged in rows, said wordlines being separated from said silicon substrate by said first oxide layer; e) implanting a P- impurity into said silicon substrate, thereby forming lightly doped said source/drain diffusion regions on opposite sides of each said wordline; f) said step of implanting said P- impurity causing said wordlines to bridge said source/drain diffusion regions, thereby forming a gate isolated from said silicon substrate by said first dielectric layer, said gate bridging a pair of said source/drain diffusion regions to form said P-channel MOSFET; g) depositing a third oxide layer superjacent said array surface; h) creating a self aligned buried contact location thereby providing a digitline junction at a first source/drain diffusion region of each said MOSFET; i) depositing a polysilicon layer superjacent said array surface, said polysilicon being doped as p-type conductivity and making direct contact to said digitline junctions at said buried contact locations; j) masking and etching said polysilicon layer to form a plurality of parallel conductive digitlines arranged in columns such that a digitline maintains electrical contact at each said digitline junction within a said column, said digitlines running perpendicular to and over said wordlines forming a 3-dimensional, waveform-like topology; k) anisotropically etching said third oxide layer; and l) implanting an P+ impurity into said source/drain diffusion regions of each said lightly doped P-channel MOSFET, said implanting taking place in regions not covered by an implant blocking remnant of said second dielectric.
Claim 24
Dependent Claim 328 words
A process for developing source/drain diffusion regions of storage node access P-channel MOSFET during fabrication of a DRAM array on a silicon substrate, said process steps comprising: a) depositing a first oxide layer superjacent surface of said array; b) depositing a first conductive layer superjacent surface of said array, said conductive layer includes p-type doped polysilicon and tungsten silicide; c) depositing a second oxide layer superjacent said first conductive layer; d) masking and etching said first conductive and said second oxide layers to form a plurality of parallel conductive wordlines arranged in rows, said wordlines being separated from said silicon substrate by said first oxide layer; e) implanting a P- impurity into said silicon substrate, thereby forming lightly doped said source/drain diffusion regions on opposite sides of each said wordline; f) said step of implanting said P- impurity causing said wordlines to bridge said source/drain diffusion regions, thereby forming a gate isolated from said silicon substrate by said first dielectric layer, said gate bridging a pair of said source/drain diffusion regions to form said P-channel MOSFET; g) depositing a third oxide layer superjacent said array surface; h) creating a self aligned buried contact location thereby providing a digitline junction at a first source/drain diffusion region of each said MOSFET; i) depositing a polysilicon layer superjacent said array surface, said polysilicon being doped as p-type conductivity and making direct contact to said digitline junctions at said buried contact locations; j) masking and etching said polysilicon layer to form a plurality of parallel conductive digitlines arranged in columns such that a digitline maintains electrical contact at each said digitline junction within a said column, said digitlines running perpendicular to and over said wordlines forming a 3-dimensional, waveform-like topology; k) anisotropically etching said third oxide layer; and l) implanting an P+ impurity into said source/drain diffusion regions of each said lightly doped P-channel MOSFET, said implanting taking place in regions not covered by an implant blocking remnant of said second dielectric.

References Cited (Backward Citations)

US4992389A Cited
US4935380A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1994-11-18 1995-05-20 1995-11-19 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1998-11-18 1999-05-20 1999-11-19 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 2002-11-18 2003-05-20 2003-11-19 $7700.00 Window Closed / Lapsed

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