Patent US1980436A successfully refreshed from Google Patents.
EP0507567A2
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EP
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Field effect transistor structure and method of fabrication
Assignee: STMicroelectronics lnc USA
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Filing: 1992-04-01
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Granted: —
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Expires: 2012-04-01
Abstract
Abstract After formation of gate electrodes (14) in a field effect device, first lightly doped drain regions (16), and opposite contactivity type halo regions (18), are formed by implant into the substrate. A first thin oxide layer (20) is then formed over the device, followed by an implant of a second lightly doped drain region (22). The second lightly doped drain region will be spaced further from the channel of the field effect device than the first lightly doped drain region vy the thickness of the thin oxide layer. A second oxide layer (24) is then formed over the device, followed by an anisotropic etch back to form sidewall regions alongside the gate electrode of the device. The sidewall regions are used to align the heavy impurity implant for forming source/drain regions.
Inventors
- 👤 Zamanian Mehdi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 01:43
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/021; H10D30/0223; H10D30/0227; H10D30/60; H10D62/00; H10D62/10; H10D62/17; H10D62/351; H10D62/357; H10D62/364; H10D62/371; H10D64/00; H10D64/01; H10D64/021; Y; Y10; Y10S; Y10S257/00; Y10S257/90
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
163 words
A method for forming a semiconductor field effect device, comprising the steps of: forming a conductive gate electrode over a semiconductor substrate having a first conductivity type; implanting impurities having a second conductivity type into the substrate, wherein first lightly doped drain regions are formed in the substrate adjacent the gate electrode; forming a first insulating layer over the substrate and the gate electrode; implanting impurities having the second conductivity type into the substrate, wherein second lightly doped drain regions are formed adjacent the first lightly doped drain regions, and wherein the second lightly doped drain regions have an impurity concentration greater than the first lightly doped drain regions; forming a second insulating layer over the first insulating layer; anisotropically etching back the first and second insulating layers to expose portions of the substrate proximate the gate electrode, and to form sidewall insulator regions alongside the gate electrode; and implanting impurities of the second conductivity type into the substrate to form source/drain regions.
Claim 2
Dependent Claim
65 words
The method of Claim 1, wherein said gate electrode forming step comprises the steps of: forming a gate insulating layer over the substrate; forming a layer of polycrystalline silicon over the gate insulating layer; and patterning the polycrystalline silicon layer to define a gate electrode; wherein the gate insulating layer lies between the substrate and portions of the first insulating layer which overly the substrate.
Claim 3
Dependent Claim
27 words
The method of Claim 2, further comprising the step of: prior to said patterning step, forming a layer of refractory metal silicide in the polycrystalline silicon layer.
Claim 4
Independent Claim
24 words
The method of any one of Claims 1 to 3, wherein the first conductivity type is P-type, and the second conductivity type is N-type.
Claim 5
Independent Claim
24 words
The method of any one of Claims 1 to 3, wherein the first conductivity type is N-type, and the second conductivity type is P-type.
Claim 6
Independent Claim
39 words
The method of any one of Claims 1 to 5, further comprising the step of: after said electrode forming step, implanting impurities of the first conductivity type to form first halo regions adjacent the gate electrode in the substrate.
Claim 7
Dependent Claim
22 words
The method of Claim 6, wherein said first halo region forming step is performed before said first lightly doped drain forming step.
Claim 8
Dependent Claim
41 words
The method of Claim 6, wherein said first halo region forming step is performed after said first lightly doped drain forming step, the first halo regions being formed to a depth greater than that of the first lightly doped drain regions.
Claim 9
Dependent Claim
34 words
The method of Claim 6, further comprising the step of: after said first insulating layer forming step, implanting impurities of the first conductivity type to form second halo regions adjacent the first halo regions.
Claim 10
Dependent Claim
22 words
The method of Claim 9, wherein said second halo region forming step is performed before said second lightly doped drain forming step.
Claim 11
Dependent Claim
53 words
The method of Claim 9, wherein said second halo region forming step is performed after said second lightly doped drain forming step, the second halo regions being formed in the substrate to a depth greater than that used for the second lightly doped drain regions and adjacent the second lightly doped drain regions.
Claim 12
Independent Claim
22 words
The method of any one of Claims 1 to 11, wherein the first and second insulating layers are formed of silicon dioxide.
Claim 13
Dependent Claim
53 words
A method according to Claim 1 wherein the step of forming a conductive gate electrode comprises the steps of: forming a gate oxide layer over a substrate having a first conductivity type; forming a conductive layer containing polycrystalline silicon over the gate oxide layer; patterning the conductive layer to define a gate electrode.
Claim 14
Dependent Claim
129 words
A semiconductor field effect device structure, comprising: a gate oxide layer on a semiconductor substrate; a conductive gate electrode on said gate oxide layer; a first oxide layer on said gate oxide adjacent said gate electrode and alongside vertical sides of said gate electrode; a second oxide region adjacent said first oxide layer, wherein said second oxide region is separated from said gate electrode by said first oxide layer, and is separated from the substrate by said gate and first oxide layers; wherein said first oxide layer in combination with said second oxide region defines a sidewall insulating region alongside said gate electrode; and impurity regions defining source/drain regions in the substrate, said impurity regions aligning approximately with an edge of the sidewall regions spaced from said gate electrode.
Claim 15
Dependent Claim
73 words
The device of Claim 14, wherein said impurity regions each comprise: a heavily doped region beyond approximately an edge of the sidewall region spaced from said gate electrode; a lightly doped drain region adjacent to said heavily doped region, and extending partway under the sidewall region; and a very lightly doped drain region adjacent said lightly doped drain region and extending to a location approximately under a vertical edge of said gate electrode.
Claim 16
Dependent Claim
38 words
The device of Claim 14 or Claim 15, further comprising: halo regions having a conductivity type opposite to that of the source drain regions, and located between said lightly doped and very lightly doped regions and the substrate.
References Cited (Backward Citations)
US4356623A
Cited
US4356623B1
Cited
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