US5478759A
Expired / Lapsed
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Method of manufacturing semiconductor device with retrograde wells
Assignee: Renesas Electronics Corp
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Filing: 1993-11-24
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Granted: 1995-12-26
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Expires: 2013-11-24
Abstract
Abstract A thick isolation oxide film is selectively formed on a surface of a silicon substrate so as to isolate an element formation region. Ions are implanted into a region in silicon substrate through the thick isolation oxide film. Thus, retrograde wells, having impurity concentration peak positions are formed in the region of silicon substrate positioned under the isolation oxide film. Then, an upper part of the isolation oxide film is removed away to form an isolation oxide film with a reduced thickness. Isolation oxide film has a reduced isolation length L. Thus, a semiconductor device is provided, which permits restriction of the narrow channel effect and the substrate biasing effect when the size of elements is reduced.
Inventors
- 👤 Tomoharu Mametani
- 👤 Masahiro Shimizu
- 👤 Katsuhiro Tsukamoto
- 👤 Hajime Arai
- 👤 Heiji Kobayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 04:22
CPC Classifications
H; H10; H10B; H10B12/00; H10B12/10; H10D; H10D84/00; H10D84/01; H10D84/0123; H10D84/0126; H10D84/0165; H10D84/0181; H10D84/0188; H10D84/02; H10D84/03; H10D84/038; H10D84/80; H10D84/82; H10D84/83; H10D84/85; H10D84/854; H10W; H10W10/00; H10W10/01; H10W10/011; H10W10/012; H10W10/0125; H10W10/0126; H10W10/0127; H10W10/10; H10W10/13
Claims Analysis
Total Claims: 49
Claim 1
Independent Claim
120 words
A method of manufacturing a semiconductor device, comprising the steps of: selectively forming an isolation insulating film having a thickness on a main surface of a semiconductor substrate to isolate an element formation region; implanting an impurity into a region of said semiconductor substrate from above the main surface of said semiconductor substrate through said isolation insulating film, thereby forming a well region having an impurity concentration distribution in the region of said semiconductor substrate positioned under said isolation insulating film; and removing a surface portion of said isolation insulating film after forming said well region so that the top surface of the peripheral portion of the isolation insulating film is positioned below the main surface of the semiconductor substrate.
Claim 2
Independent Claim
120 words
A method of manufacturing a semiconductor device, comprising the steps of: selectively forming an isolation insulating film having a thickness on a main surface of a semiconductor substrate to isolate an element formation region; implanting an impurity into a region of said semiconductor substrate from above the main surface of said semiconductor substrate through said isolation insulating film, thereby forming a well region having an impurity concentration distribution in the region of said semiconductor substrate positioned under said isolation insulating film; and removing a surface portion of said isolation insulating film after forming said well region so that the top surface of the peripheral portion of the isolation insulating film is positioned below the main surface of the semiconductor substrate.
Claim 3
Dependent Claim
33 words
A method of manufacturing a semiconductor device as recited in claim 1, wherein said step of forming said isolation insulating film includes a step of forming an oxide film by a LOCOS process.
Claim 4
Dependent Claim
52 words
A method of manufacturing a semiconductor device as recited in claim 1, wherein said step of forming said well region includes the steps of: implanting said impurity into said semiconductor substrate with a first energy; and implanting said impurity into said semiconductor substrate with a second energy higher than said first energy.
Claim 5
Dependent Claim
35 words
A method of manufacturing a semiconductor device as recited in claim 1, wherein said step of removing the surface portion of said isolation insulating film includes etching said surface portion of said isolation insulating film.
Claim 6
Independent Claim
141 words
A method of manufacturing a semiconductor memory device including a memory cell array region and a peripheral circuit region, comprising the steps of: selectively forming on a main surface of a semiconductor substrate an isolation insulating film having a thickness to isolate an element formation region included in said memory cell array region and said peripheral circuit region; implanting an impurity into a region of said semiconductor substrate from above the main surface of said semiconductor substrate through said isolation insulating film, thereby forming a well region having an impurity concentration distribution in the region of said semiconductor substrate positioned under said isolation insulating film; and subsequently selectively removing the surface portion of the isolation insulating film positioned in said memory cell array region so that the thickness of the isolation insulating film in said memory cell array region is reduced.
Claim 7
Independent Claim
141 words
A method of manufacturing a semiconductor memory device including a memory cell array region and a peripheral circuit region, comprising the steps of: selectively forming on a main surface of a semiconductor substrate an isolation insulating film having a thickness to isolate an element formation region included in said memory cell array region and said peripheral circuit region; implanting an impurity into a region of said semiconductor substrate from above the main surface of said semiconductor substrate through said isolation insulating film, thereby forming a well region having an impurity concentration distribution in the region of said semiconductor substrate positioned under said isolation insulating film; and subsequently selectively removing the surface portion of the isolation insulating film positioned in said memory cell array region so that the thickness of the isolation insulating film in said memory cell array region is reduced.
Claim 8
Independent Claim
157 words
A method of manufacturing a semiconductor device, comprising the steps of: selectively forming on a main surface of a semiconductor substrate an isolation insulating film to isolate an element formation region; forming a mask layer to expose a surface of said isolation insulating film; implanting an impurity, in a first implanting step, through said exposed isolation insulating film, thereby forming a first impurity region in a region in said semiconductor substrate; implanting a second impurity, in a second implantation step at a greater implantation energy than the first implantation step, in a region at a greater distance from the surface of said semiconductor substrate than said first impurity region from above the main surface of said semiconductor substrate; and removing a surface portion of said isolation insulating film after forming said well region so that the top surface of the peripheral portion of the isolation insulating film is positioned below the main surface of the semiconductor substrate.
Claim 9
Independent Claim
157 words
A method of manufacturing a semiconductor device, comprising the steps of: selectively forming on a main surface of a semiconductor substrate an isolation insulating film to isolate an element formation region; forming a mask layer to expose a surface of said isolation insulating film; implanting an impurity, in a first implanting step, through said exposed isolation insulating film, thereby forming a first impurity region in a region in said semiconductor substrate; implanting a second impurity, in a second implantation step at a greater implantation energy than the first implantation step, in a region at a greater distance from the surface of said semiconductor substrate than said first impurity region from above the main surface of said semiconductor substrate; and removing a surface portion of said isolation insulating film after forming said well region so that the top surface of the peripheral portion of the isolation insulating film is positioned below the main surface of the semiconductor substrate.
Claim 10
Independent Claim
177 words
A method of manufacturing a semiconductor device, comprising the steps of: selectively forming on a main surface of a semiconductor substrate an isolation insulating film to isolate an element formation region; forming a mask layer to expose a surface of said isolation insulating film; implanting an impurity, in a first implanting step, through said exposed isolation insulating film, thereby forming a first impurity region in a region in said semiconductor substrate; and implanting a second impurity, in a second implantation step at a greater implantation energy than the first implantation step, in a region at a greater distance from the surface of said semiconductor substrate than said first impurity region from above the main surface of said semiconductor substrate, wherein said first impurity region has a first impurity concentration peak portion, said second impurity region has a second impurity concentration peak portion, and a third impurity concentration peak portion under the second impurity concentration peak portion, and said first impurity concentration peak portion and said second impurity concentration peak portion are formed individually without a shared portion.
Claim 11
Independent Claim
177 words
A method of manufacturing a semiconductor device, comprising the steps of: selectively forming on a main surface of a semiconductor substrate an isolation insulating film to isolate an element formation region; forming a mask layer to expose a surface of said isolation insulating film; implanting an impurity, in a first implanting step, through said exposed isolation insulating film, thereby forming a first impurity region in a region in said semiconductor substrate; and implanting a second impurity, in a second implantation step at a greater implantation energy than the first implantation step, in a region at a greater distance from the surface of said semiconductor substrate than said first impurity region from above the main surface of said semiconductor substrate, wherein said first impurity region has a first impurity concentration peak portion, said second impurity region has a second impurity concentration peak portion, and a third impurity concentration peak portion under the second impurity concentration peak portion, and said first impurity concentration peak portion and said second impurity concentration peak portion are formed individually without a shared portion.
Claim 12
Dependent Claim
31 words
A method of manufacturing a semiconductor device as recited in claim 6, wherein said first impurity region is a channel cut layer, and said second impurity region includes a retrograde well.
Claim 13
Dependent Claim
31 words
A method of manufacturing a semiconductor device as recited in claim 6, wherein said first impurity region is formed to be positioned only in a region under said isolation insulating film.
Claim 14
Dependent Claim
27 words
A method of manufacturing a semiconductor device as recited in claim 6, wherein said mask layer is formed to cover the periphery of said isolation insulating film.
Claim 15
Dependent Claim
29 words
A method of manufacturing a semiconductor device as recited in claim 6, wherein the position to form said second impurity region is selected independently of said first impurity region.
Claim 16
Independent Claim
96 words
A method of manufacturing a semiconductor device, comprising the steps of: selectively forming on a main surface of a semiconductor substrate an element isolation layer to isolate an element formation region; forming on said element isolation layer a mask layer to expose a surface of said element formation region; conducting two separate impurity implantations through said mask layer and said element isolation layer, thereby forming an impurity region extending from a first region in said semiconductor substrate to a second region at a greater distance from the surface of said semiconductor substrate than the first region.
Claim 17
Independent Claim
96 words
A method of manufacturing a semiconductor device, comprising the steps of: selectively forming on a main surface of a semiconductor substrate an element isolation layer to isolate an element formation region; forming on said element isolation layer a mask layer to expose a surface of said element formation region; conducting two separate impurity implantations through said mask layer and said element isolation layer, thereby forming an impurity region extending from a first region in said semiconductor substrate to a second region at a greater distance from the surface of said semiconductor substrate than the first region.
Claim 18
Dependent Claim
22 words
A method of manufacturing a semiconductor device as recited in claim 12, wherein said element isolation layer includes an isolation insulating film.
Claim 19
Independent Claim
111 words
A method of manufacturing a semiconductor device, comprising the steps of: selectively forming on a main surface of a semiconductor substrate an element isolation layer to isolate an element formation region; forming on said element isolation layer a mask layer to expose a surface of said element formation region; implanting an impurity through said mask layer and said element isolation layer, thereby forming an impurity region extending from a first region in said semiconductor substrate to a second region at a greater distance from the surface of said semiconductor substrate than the first region; wherein said mask layer is formed to cover the entire upper surface of said element isolation layer.
Claim 20
Independent Claim
111 words
A method of manufacturing a semiconductor device, comprising the steps of: selectively forming on a main surface of a semiconductor substrate an element isolation layer to isolate an element formation region; forming on said element isolation layer a mask layer to expose a surface of said element formation region; implanting an impurity through said mask layer and said element isolation layer, thereby forming an impurity region extending from a first region in said semiconductor substrate to a second region at a greater distance from the surface of said semiconductor substrate than the first region; wherein said mask layer is formed to cover the entire upper surface of said element isolation layer.
Claim 21
Dependent Claim
62 words
A method of manufacturing a semiconductor device as recited in claim 12, wherein said impurity region has a first impurity concentration peak portion, and a second impurity concentration peak portion positioned under the first impurity concentration peak portion, and the position of said first impurity concentration peak portion under said element formation region is determined by the thickness of said mask layer.
Claim 22
Dependent Claim
76 words
A method of manufacturing a semiconductor device as recited in claim 12, wherein said impurity region has a first impurity concentration peak portion, and a second impurity concentration peak portion positioned under the first impurity concentration peak portion, and the distance between said first and second impurity concentration peak portions positioned under said isolation insulating film is larger than the distance between said first and second impurity concentration peak portions positioned under said element formation region.
Claim 23
Dependent Claim
24 words
A method of manufacturing a semiconductor device as recited in claim 12, wherein said mask layer constitutes a part of said element isolation layer.
Claim 24
Dependent Claim
20 words
A method of manufacturing a semiconductor device as recited in claim 17, wherein said mask layer is an oxide film.
Claim 25
Dependent Claim
24 words
A method of manufacturing a semiconductor device as recited in claim 17, wherein said mask layer is a TEOS (Tetra Ethyl Ortho Silicate) film.
Claim 26
Dependent Claim
20 words
A method of manufacturing a semiconductor device as recited in claim 17, wherein said mask layer is a nitride film.
Claim 27
Dependent Claim
84 words
A method of manufacturing a semiconductor device as recited in claim 17, wherein said step of forming the mask layer includes the steps of: forming a TEOS film on the entire main surface of said semiconductor substrate using a chemical vapor deposition process; forming a patterned resist on said TEOS film at a portion positioned on said element isolation layer; performing etching using said patterned resist as a mask, thereby leaving said TEOS film on said element isolation layer; and removing said patterned resist.
Claim 28
Dependent Claim
84 words
A method of manufacturing a semiconductor device as recited in claim 17, wherein said step of forming the mask layer includes the steps of: forming a nitride film on the entire main surface of said semiconductor substrate using a chemical vapor deposition process; forming a patterned resist on said nitride film at a portion positioned on said element isolation layer; performing etching using said patterned resist as a mask, thereby leaving said nitride film on said element isolation layer; and removing said patterned resist.
Claim 29
Dependent Claim
21 words
A method of manufacturing a semiconductor device as recited in claim 12, further comprising a step of removing said mask layer.
Claim 30
Dependent Claim
57 words
A method of manufacturing a semiconductor device as recited in claim 12, wherein said step of forming the element isolation layer includes the steps of: forming on said main surface of said semiconductor substrate an oxide film having a thickness by CVD; and patterning said oxide film, thereby leaving said oxide film in the element isolation region.
Claim 31
Dependent Claim
30 words
A method of manufacturing a semiconductor device as recited in claim 24, wherein said oxide film is formed on the entire main surface of said semiconductor substrate by thermal oxidation.
Claim 32
Dependent Claim
52 words
A method of manufacturing a semiconductor device as recited in claim 24, wherein said impurity region has a first impurity concentration peak portion, and a second impurity concentration peak portion under the first impurity concentration peak portion, and said first impurity concentration peak portion is formed after said oxide film is patterned.
Claim 33
Independent Claim
205 words
A method of manufacturing a semiconductor device, comprising the steps of: selectively forming on a main surface of a semiconductor substrate an element isolation layer to isolate an element formation region; forming on said element isolation layer a mask layer to expose a surface of said element formation region; implanting an impurity through said mask layer and said element isolation layer, thereby forming an impurity region extending from a first region in said semiconductor substrate to a second region at a greater distance from the surface of said semiconductor substrate than the first region; wherein said step of forming the element isolation layer includes the steps of: forming on said main surface of said semiconductor substrate an oxide film having a thickness by CVD; and patterning said oxide film, thereby leaving said oxide film in the element isolation region, and wherein said impurity region has a first impurity concentration peak portion, and a second impurity concentration peak portion under the first impurity concentration peak portion, said first impurity concentration peak portion is formed by implanting said impurity through said oxide film and said mask layer before said oxide film is patterned, and then said oxide film is patterned using said mask layer as a mask.
Claim 34
Independent Claim
205 words
A method of manufacturing a semiconductor device, comprising the steps of: selectively forming on a main surface of a semiconductor substrate an element isolation layer to isolate an element formation region; forming on said element isolation layer a mask layer to expose a surface of said element formation region; implanting an impurity through said mask layer and said element isolation layer, thereby forming an impurity region extending from a first region in said semiconductor substrate to a second region at a greater distance from the surface of said semiconductor substrate than the first region; wherein said step of forming the element isolation layer includes the steps of: forming on said main surface of said semiconductor substrate an oxide film having a thickness by CVD; and patterning said oxide film, thereby leaving said oxide film in the element isolation region, and wherein said impurity region has a first impurity concentration peak portion, and a second impurity concentration peak portion under the first impurity concentration peak portion, said first impurity concentration peak portion is formed by implanting said impurity through said oxide film and said mask layer before said oxide film is patterned, and then said oxide film is patterned using said mask layer as a mask.
Claim 35
Independent Claim
123 words
A method of manufacturing a semiconductor device, comprising the steps of: selectively forming on a main surface of a semiconductor substrate an element isolation layer to isolate an element formation region; forming on said element isolation layer a mask layer to expose a surface of said element formation region; implanting an impurity through said mask layer and said element isolation layer, thereby forming an impurity region extending from a first region in said semiconductor substrate to a second region at a greater distance from the surface of said semiconductor substrate than the first region, wherein said element isolation layer includes a stacked layer structure formed of an insulating layer formed on said semiconductor substrate and a conductive layer formed on the insulating layer.
Claim 36
Independent Claim
123 words
A method of manufacturing a semiconductor device, comprising the steps of: selectively forming on a main surface of a semiconductor substrate an element isolation layer to isolate an element formation region; forming on said element isolation layer a mask layer to expose a surface of said element formation region; implanting an impurity through said mask layer and said element isolation layer, thereby forming an impurity region extending from a first region in said semiconductor substrate to a second region at a greater distance from the surface of said semiconductor substrate than the first region, wherein said element isolation layer includes a stacked layer structure formed of an insulating layer formed on said semiconductor substrate and a conductive layer formed on the insulating layer.
Claim 37
Dependent Claim
21 words
A method of manufacturing a semiconductor device as recited in claim 28, wherein said conductive layer is a polycrystalline silicon layer.
Claim 38
Independent Claim
150 words
A method of manufacturing a semiconductor device, comprising the steps of: selectively forming on a main surface of a semiconductor substrate an element isolation layer to isolate an element formation region; forming on said element isolation layer a mask layer to expose a surface of said element formation region; implanting an impurity through said mask layer and said element isolation layer, thereby forming an impurity region extending from a first region in said semiconductor substrate to a second region at a greater distance from the surface of said semiconductor substrate than the first region, wherein an insulating layer and a conductive layer constituting said element isolation layer are formed in turn on the entire main surface of said semiconductor substrate, a mask layer is patterned on said conductive layer, and said element isolation layer is left on the element isolation region by performing etching using said mask layer as mask.
Claim 39
Independent Claim
150 words
A method of manufacturing a semiconductor device, comprising the steps of: selectively forming on a main surface of a semiconductor substrate an element isolation layer to isolate an element formation region; forming on said element isolation layer a mask layer to expose a surface of said element formation region; implanting an impurity through said mask layer and said element isolation layer, thereby forming an impurity region extending from a first region in said semiconductor substrate to a second region at a greater distance from the surface of said semiconductor substrate than the first region, wherein an insulating layer and a conductive layer constituting said element isolation layer are formed in turn on the entire main surface of said semiconductor substrate, a mask layer is patterned on said conductive layer, and said element isolation layer is left on the element isolation region by performing etching using said mask layer as mask.
Claim 40
Dependent Claim
53 words
A method of manufacturing a semiconductor device as recited in claim 30, wherein said impurity region has a first impurity concentration peak portion and a second impurity concentration peak portion under the first impurity concentration peak portion, and said first impurity concentration peak portion is formed after said element isolation layer is patterned.
Claim 41
Dependent Claim
84 words
A method of manufacturing a semiconductor device as recited in claim 30, wherein said impurity region has a first impurity concentration peak portion and a second impurity concentration peak portion under the first impurity concentration peak portion, said first impurity concentration peak portion is formed by implanting said impurity through said insulating layer, said conductive layer, and said mask layer before said element isolation layer is patterned, and then said insulating layer and said conductive layer are patterned using said mask layer as mask.
Claim 42
Independent Claim
101 words
A method of manufacturing a semiconductor device, comprising the steps of: selectively implanting an impurity into a first region in an element isolation region of a semiconductor substrate; forming on a main surface of said semiconductor substrate an isolation insulating film having a thickness in a second region including and surrounding said first region in said element isolation region, thereby forming a first impurity region in said first region; and forming a second impurity region from above the main surface of said semiconductor substrate in a region further away from the surface of said semiconductor substrate than said first impurity region.
Claim 43
Independent Claim
101 words
A method of manufacturing a semiconductor device, comprising the steps of: selectively implanting an impurity into a first region in an element isolation region of a semiconductor substrate; forming on a main surface of said semiconductor substrate an isolation insulating film having a thickness in a second region including and surrounding said first region in said element isolation region, thereby forming a first impurity region in said first region; and forming a second impurity region from above the main surface of said semiconductor substrate in a region further away from the surface of said semiconductor substrate than said first impurity region.
Claim 44
Dependent Claim
51 words
A method of manufacturing a semiconductor device as recited in claim 33, wherein said step of implanting the impurity includes the steps of: exposing said first region on said semiconductor substrate and forming a patterned resist; and implanting said impurity into said semiconductor substrate using said patterned resist as a mask.
Claim 45
Dependent Claim
87 words
A method of manufacturing a semiconductor device as recited in claim 33, wherein said isolation insulating film is an oxide film, and said isolation insulating film forming step includes steps of forming an insulating film, and a nitride film in turn on said main surface of said semiconductor substrate; patterning said insulating film and said nitride film, thereby forming an opening to expose said second region in said insulating film and said nitride film; and forming said isolation insulating film in said second region by selective oxidation.
Claim 46
Dependent Claim
37 words
A method of manufacturing a semiconductor device as recited in claim 35, wherein conditions for said selective oxidation are selected so that said first impurity region is positioned only in the region under said isolation insulating film.
Claim 47
Dependent Claim
72 words
A method of manufacturing a semiconductor device as recited in claim 33, wherein a peripheral portion of said first region in the main surface of said semiconductor substrate, and a peripheral portion of said second region in the main surface of said semiconductor substrate are spaced apart from each other by a distance not greater than a maximum distance over which said impurity is diffused when said isolation insulating film is formed.
Claim 48
Dependent Claim
31 words
A method of manufacturing a semiconductor device as recited in claim 33, wherein said first impurity region is a channel cut layer, and said second impurity region includes a retrograde well.
Claim 49
Dependent Claim
29 words
A method of manufacturing a semiconductor device as recited in claim 33, wherein the position to form said second impurity region is selected independently of said first impurity region.
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