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US5266513A Expired / Lapsed US ⏱️ 0.0 years remaining

Method of making stacked W-cell capacitor

Assignee: Micron Technology Inc
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Filing: 1992-11-19
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Granted: 1993-11-30
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Expires: 2012-11-19
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Abstract

Abstract A stacked multi fingered cell (SMFC) capacitor using a modified stacked capacitor storage cell fabrication process. The SMFC is made up of polysilicon structure, having a multi-fingered cross-section, located at a buried contact and extending to an adjacent storage node overlaid by polysilicon with a dielectric sandwiched in between. The addition of the polysilicon structure increases storage capability 120% without enlarging the surface area defined for a normal stacked capacitor cell.

Inventors

  • 👤 Pierre C. Fazan
  • 👤 Charles H. Dennison
  • 👤 Ruojia Lee
  • 👤 Yauh-Ching Liu

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-30 16:51
CPC Classifications
H; H10; H10B; H10B12/00; H10B12/30; H10B12/31; H10B12/318

Claims Analysis

Total Claims: 10
Claim 1
Independent Claim 282 words
A process for fabricating a DRAM storage capacitor on a silicon substrate having active areas, word lines and digit lines, said process comprising the steps of: forming a dielectric layer superjacent the surface of said silicon substrate; creating an aligned buried contact location at a storage node junction in each said active area, wherein said aligned buried contact location is defined by a patterned photomask which exposes a portion of said first dielectric layer, said exposed dielectric layer being etched away to expose said storage node junction; forming a first conductive layer superadjacent the patterned dielectric layer, said first conductive layer making contact to said storage node junction at said buried contact location; patterning said first conductive layer to form a portion of a storage node plate at each said storage node junction, said storage node plate portion remaining in contact to said storage node junction at said buried contact location; isotropically etching a remaining portion of said dielectric layer to thereby expose an underneath portion of said patterned first conductive layer, said underneath portion extending from said storage node junction to a gap between two adjacent word lines; forming a second conductive layer superjacent said patterned first conductive layer and said exposed underneath first conductive layer portion, said second conductive layer combining with said first conductive layer; patterning and dry etching said second conductive layer to form a complete storage node plate at said storage node junction, said storage node plate having a multi-fingered cross-section; forming a cell dielectric layer adjacent and coextensive with said storage node plate and adjacent existing substrate surface; and forming a third conductive layer adjacent and coextensive said cell dielectric layer to form a top cell.
Claim 2
Dependent Claim 282 words
A process for fabricating a DRAM storage capacitor on a silicon substrate having active areas, word lines and digit lines, said process comprising the steps of: forming a dielectric layer superjacent the surface of said silicon substrate; creating an aligned buried contact location at a storage node junction in each said active area, wherein said aligned buried contact location is defined by a patterned photomask which exposes a portion of said first dielectric layer, said exposed dielectric layer being etched away to expose said storage node junction; forming a first conductive layer superadjacent the patterned dielectric layer, said first conductive layer making contact to said storage node junction at said buried contact location; patterning said first conductive layer to form a portion of a storage node plate at each said storage node junction, said storage node plate portion remaining in contact to said storage node junction at said buried contact location; isotropically etching a remaining portion of said dielectric layer to thereby expose an underneath portion of said patterned first conductive layer, said underneath portion extending from said storage node junction to a gap between two adjacent word lines; forming a second conductive layer superjacent said patterned first conductive layer and said exposed underneath first conductive layer portion, said second conductive layer combining with said first conductive layer; patterning and dry etching said second conductive layer to form a complete storage node plate at said storage node junction, said storage node plate having a multi-fingered cross-section; forming a cell dielectric layer adjacent and coextensive with said storage node plate and adjacent existing substrate surface; and forming a third conductive layer adjacent and coextensive said cell dielectric layer to form a top cell.
Claim 3
Dependent Claim 22 words
A process as recited in claim 1, wherein said dielectric layer is selected from the group consisting essentially of oxide and nitride.
Claim 4
Dependent Claim 20 words
A process as recited in claim 1, wherein said etching of said dielectric is a controlled phosphoric acid wet etch.
Claim 5
Dependent Claim 20 words
A process as recited in claim 1, wherein said etching of said dielectric is a controlled hydrofluoric acid wet etch.
Claim 6
Dependent Claim 14 words
A process as recited in claim 1, wherein said buried contact is self aligned.
Claim 7
Dependent Claim 17 words
A process as recited in claim 1, wherein said first and second conductive layers are doped polysilicon.
Claim 8
Dependent Claim 20 words
A process as recited in claim 6, wherein said first and second conductive layers are deposited by low temperature deposition.
Claim 9
Dependent Claim 17 words
A process as recited in claim 1, wherein said dielectric layer is deposited by chemical vapor deposition.
Claim 10
Dependent Claim 14 words
A process as recited in claim 1, wherein said cell dielectric layer is nitride.

References Cited (Backward Citations)

US5071783A Cited
US4977102A Cited
JPH0272672A Cited
JPH0279468A Cited
JPH02135775A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1996-11-29 1997-05-31 1997-11-30 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 2000-11-29 2001-05-31 2001-11-30 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 2004-11-29 2005-05-31 2005-11-30 $7700.00 Window Closed / Lapsed

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