Patent US6017785A successfully refreshed from Google Patents.
US6017785A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for improving latch-up immunity and interwell isolation in a semiconductor device
Assignee: Renesas Electronics America Inc
•
Filing: 1996-08-15
•
Granted: 2000-01-25
•
Expires: 2016-08-15
Abstract
Abstract A method of improving latch-up immunity and interwell isolation in a semiconductor device is provided. In one embodiment, an implant mask which has a variable permeability to implanted impurities is formed on the surface of a substrate having a first dopant region. A first portion of the implant mask overlies a first portion of the first dopant region. The structure is subjected to high energy implantation which forms a heavily doped region. A first portion of the heavily doped region is located along the lower boundary of the first dopant region. A second portion of the heavily doped region which extends along a side boundary of the first dopant region is formed by impurity ions which pass through the first portion of the implant mask. The heavily doped region improves latch-up immunity and interwell isolation without degrading threshold voltage tolerance. In alternative embodiments, one variable permeability mask is used to form the first dopant region and also to form the heavily doped region continuous with the first dopant region.
Inventors
- 👤 Chung-Chyung Han
- 👤 Jeong Yeol Choi
- 👤 Cheun-Der Lien
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 20:48
CPC Classifications
H; H10; H10D; H10D84/00; H10D84/80; H10D84/82; H10D84/83; H10D84/85; H10D84/854; H10D84/01; H10D84/0123; H10D84/0126; H10D84/0165; H10D84/0188; H10D84/02; H10D84/03; H10D84/038; Y; Y10; Y10S; Y10S438/00; Y10S438/981
Claims Analysis
Total Claims: 41
Claim 1
Independent Claim
145 words
A method of forming a semiconductor device from a substrate, said substrate having a first semiconductor region, said method comprising the steps of: forming an implant mask having a first portion and a second portion over an upper surface of said substrate, said first portion overlying a first portion of said first semiconductor region; and implanting impurities into said implant mask wherein said impurities pass through said first portion of said implant mask and do not pass through said second portion of said implant mask, wherein said impurities enter into said first portion of said first semiconductor region after passing through said first portion of said implant mask thereby creating a second semiconductor region, and wherein, during said step of implanting, said impurities enter into a second portion of said first semiconductor region not covered by said implant mask thereby creating a third semiconductor region.
Claim 2
Independent Claim
145 words
A method of forming a semiconductor device from a substrate, said substrate having a first semiconductor region, said method comprising the steps of: forming an implant mask having a first portion and a second portion over an upper surface of said substrate, said first portion overlying a first portion of said first semiconductor region; and implanting impurities into said implant mask wherein said impurities pass through said first portion of said implant mask and do not pass through said second portion of said implant mask, wherein said impurities enter into said first portion of said first semiconductor region after passing through said first portion of said implant mask thereby creating a second semiconductor region, and wherein, during said step of implanting, said impurities enter into a second portion of said first semiconductor region not covered by said implant mask thereby creating a third semiconductor region.
Claim 3
Dependent Claim
31 words
The method of claim 1 wherein said impurities do not significantly affect a dopant concentration of said second portion of said first semiconductor region near said upper surface of said substrate.
Claim 4
Dependent Claim
50 words
The method of claim 1 wherein said first semiconductor region has a lower boundary located below said upper surface and a side boundary extending from said upper surface to said lower boundary, said second semiconductor region located along said side boundary, said third semiconductor region located along said lower boundary.
Claim 5
Dependent Claim
37 words
The method of claim 1 wherein said second semiconductor region and said third semiconductor region are substantially continuous and have a substantially uniform dopant concentration which is greater than a dopant concentration of said first semiconductor region.
Claim 6
Dependent Claim
29 words
The method of claim 4 wherein said second semiconductor region and said third semiconductor region have dopant concentrations greater than or equal to approximately 1.0×10 17 atoms/cm 3 .
Claim 7
Dependent Claim
26 words
The method of claim 1 wherein said second semiconductor region and said third semiconductor region are regions with low resistivities which inhibit vertical and lateral latch-up.
Claim 8
Independent Claim
136 words
A method of forming a semiconductor device from a substrate, said substrate having a first semiconductor region, said method comprising the steps of: forming an implant mask having a first portion and a second portion over an upper surface of said substrate, said first portion overlying a first portion of said first semiconductor region, said first portion having a sloped surface; and implanting impurities into said implant mask wherein said impurities pass through said first portion of said implant mask and wherein said impurities do not pass through said second portion of said implant mask; said method further comprising the steps of: depositing a photoresist on said substrate; patterning said photoresist to form a photoresist mask which has a substantially perpendicular side; and heating said photoresist mask to form said implant mask with said sloped surface.
Claim 9
Independent Claim
136 words
A method of forming a semiconductor device from a substrate, said substrate having a first semiconductor region, said method comprising the steps of: forming an implant mask having a first portion and a second portion over an upper surface of said substrate, said first portion overlying a first portion of said first semiconductor region, said first portion having a sloped surface; and implanting impurities into said implant mask wherein said impurities pass through said first portion of said implant mask and wherein said impurities do not pass through said second portion of said implant mask; said method further comprising the steps of: depositing a photoresist on said substrate; patterning said photoresist to form a photoresist mask which has a substantially perpendicular side; and heating said photoresist mask to form said implant mask with said sloped surface.
Claim 10
Dependent Claim
30 words
The method of claim 7 wherein said step of heating further comprises the step of controlling a slope of said sloped surface by controlling the duration of said heating step.
Claim 11
Dependent Claim
37 words
The method of claim 7 wherein said step of heating further comprises the step of controlling a slope of said sloped surface by controlling the temperature to which said photoresist mask is heated during said heating step.
Claim 12
Independent Claim
124 words
A method of forming a semiconductor device from a substrate, said substrate having a first semiconductor region, said method comprising the steps of: forming an implant mask having a first portion and a second portion over an upper surface of said substrate, said first portion overlying a first portion of said first semiconductor region, said first portion having a sloped surface; and implanting impurities into said implant mask wherein said impurities pass through said first portion of said implant mask and wherein said impurities do not pass through said second portion of said implant mask; wherein said step of forming said implant mask comprises the steps of: depositing a photoresist over said upper surface of said substrate; and patterning said photoresist using defocused light.
Claim 13
Independent Claim
124 words
A method of forming a semiconductor device from a substrate, said substrate having a first semiconductor region, said method comprising the steps of: forming an implant mask having a first portion and a second portion over an upper surface of said substrate, said first portion overlying a first portion of said first semiconductor region, said first portion having a sloped surface; and implanting impurities into said implant mask wherein said impurities pass through said first portion of said implant mask and wherein said impurities do not pass through said second portion of said implant mask; wherein said step of forming said implant mask comprises the steps of: depositing a photoresist over said upper surface of said substrate; and patterning said photoresist using defocused light.
Claim 14
Independent Claim
164 words
A method of forming a semiconductor device from a substrate, said substrate having a first semiconductor region, said method comprising the steps of: forming an implant mask having a first portion and a second portion over an upper surface of said substrate, said first portion overlain a first portion of said first semiconductor region, said first portion having a sloped surface; and implanting impurities into said implant mask wherein said impurities pass through said first portion of said implant mask and wherein said impurities do not pass through said second portion of said implant mask; wherein said step of forming said implant mask comprises the steps of: depositing a first layer over said upper surface of said substrate; depositing a photoresist over said first layer; patterning said photoresist to form a photoresist mask and expose a portion of said first layer; etching said exposed portion of said first layer isotropically to form said implant mask having said sloped surface; and stripping said photoresist mask.
Claim 15
Independent Claim
164 words
A method of forming a semiconductor device from a substrate, said substrate having a first semiconductor region, said method comprising the steps of: forming an implant mask having a first portion and a second portion over an upper surface of said substrate, said first portion overlain a first portion of said first semiconductor region, said first portion having a sloped surface; and implanting impurities into said implant mask wherein said impurities pass through said first portion of said implant mask and wherein said impurities do not pass through said second portion of said implant mask; wherein said step of forming said implant mask comprises the steps of: depositing a first layer over said upper surface of said substrate; depositing a photoresist over said first layer; patterning said photoresist to form a photoresist mask and expose a portion of said first layer; etching said exposed portion of said first layer isotropically to form said implant mask having said sloped surface; and stripping said photoresist mask.
Claim 16
Dependent Claim
26 words
The method of claim 11 wherein said first layer is selected from the group consisting of oxide, nitride, phosphosilicate glass (PSG), polysilicon and a combination thereof.
Claim 17
Independent Claim
128 words
A method of forming a semiconductor device from a substrate, said substrate having a first semiconductor region, said method comprising the steps of: forming an implant mask having a first portion and a second portion over an upper surface of said substrate, said first portion overlying a first portion of said first semiconductor region, wherein said implant mask is formed from a first layer and a second layer and wherein said first portion of said implant mask comprises said first layer and said second portion of said implant mask comprises said first layer and said second layer; and implanting impurities into said implant mask wherein said impurities pass through said first portion of said implant mask and do not pass through said second portion of said implant mask.
Claim 18
Independent Claim
128 words
A method of forming a semiconductor device from a substrate, said substrate having a first semiconductor region, said method comprising the steps of: forming an implant mask having a first portion and a second portion over an upper surface of said substrate, said first portion overlying a first portion of said first semiconductor region, wherein said implant mask is formed from a first layer and a second layer and wherein said first portion of said implant mask comprises said first layer and said second portion of said implant mask comprises said first layer and said second layer; and implanting impurities into said implant mask wherein said impurities pass through said first portion of said implant mask and do not pass through said second portion of said implant mask.
Claim 19
Dependent Claim
32 words
The method of claim 13 wherein said first layer is photoresist and said second layer is selected from the group consisting of oxide, nitride, phosphosilicate glass (PSG), polysilicon and a combination thereof.
Claim 20
Dependent Claim
77 words
The method of claim 13 further comprising the steps of: depositing an oxide layer over said substrate; depositing a photoresist over said oxide layer; patterning said photoresist to form a photoresist mask which exposes a portion of said oxide layer; and etching said exposed portion of said oxide layer anisotropically and then isotropically thereby leaving a portion of said photoresist mask overhanging, said overhanging portion of said photoresist mask forming said first portion of said implant mask.
Claim 21
Dependent Claim
92 words
The method of claim 13 further comprising the steps of: depositing an oxide layer over said substrate; depositing a photoresist over said oxide layer; patterning said photoresist to form a photoresist mask which exposes a portion of said oxide layer; removing said exposed portion of said oxide layer by performing an anisotropic etch to form a patterned oxide layer; and removing a portion of said photoresist mask thereby exposing a portion of said patterned oxide layer, said exposed portion of said patterned oxide layer forming said first portion of said implant mask.
Claim 22
Independent Claim
136 words
A method of forming a semiconductor device from a substrate, said substrate having a first semiconductor region, said method comprising the steps of: forming an implant mask having a first portion and a second portion over an upper surface of said substrate, said first portion overlying a first portion of said first semiconductor region; and implanting impurities into said implant mask wherein said impurities pass through said first portion of said implant mask and wherein said impurities do not pass through said second portion of said implant mask, wherein said first semiconductor region has a first conductivity type and said impurities are of said first conductivity type, and wherein said substrate has a fourth semiconductor region of a second conductivity type opposite said first conductivity type adjacent to said first portion of said first semiconductor region.
Claim 23
Independent Claim
136 words
A method of forming a semiconductor device from a substrate, said substrate having a first semiconductor region, said method comprising the steps of: forming an implant mask having a first portion and a second portion over an upper surface of said substrate, said first portion overlying a first portion of said first semiconductor region; and implanting impurities into said implant mask wherein said impurities pass through said first portion of said implant mask and wherein said impurities do not pass through said second portion of said implant mask, wherein said first semiconductor region has a first conductivity type and said impurities are of said first conductivity type, and wherein said substrate has a fourth semiconductor region of a second conductivity type opposite said first conductivity type adjacent to said first portion of said first semiconductor region.
Claim 24
Independent Claim
102 words
A method of forming a semiconductor device from a substrate, said substrate having a first semiconductor region, said method comprising the steps of: forming an implant mask having a first portion and a second portion over an upper surface of said substrate, said first portion overlying a first portion of said first semiconductor region, wherein said first portion of said implant mask has a concave or convex surface; and implanting impurities into said implant mask wherein said impurities pass through said first portion of said implant mask and wherein said impurities do not pass through said second portion of said implant mask.
Claim 25
Independent Claim
102 words
A method of forming a semiconductor device from a substrate, said substrate having a first semiconductor region, said method comprising the steps of: forming an implant mask having a first portion and a second portion over an upper surface of said substrate, said first portion overlying a first portion of said first semiconductor region, wherein said first portion of said implant mask has a concave or convex surface; and implanting impurities into said implant mask wherein said impurities pass through said first portion of said implant mask and wherein said impurities do not pass through said second portion of said implant mask.
Claim 26
Independent Claim
191 words
A method of forming a semiconductor device from a substrate, said substrate having a first semiconductor region of a first conductivity type and a second semiconductor region of a second conductivity type opposite said first conductivity type adjacent to said first semiconductor region, said method comprising the steps of: forming a first implant mask having a first portion and a second portion over said substrate, said first portion overlying a first portion of said first semiconductor region and said second portion overlying said second semiconductor region; performing a first high energy implantation wherein first conductivity type impurities pass through said first portion of said first implant mask to form a third semiconductor region in said first portion of said first semiconductor region; stripping said first implant mask; forming a second implant mask having a first portion overlying a first portion of said second semiconductor region and a second portion overlying said first semiconductor region; and performing a second high energy implantation wherein second conductivity type impurities pass through said first portion of said second implant mask to form a fourth semiconductor region in said first portion of said second semiconductor region.
Claim 27
Independent Claim
191 words
A method of forming a semiconductor device from a substrate, said substrate having a first semiconductor region of a first conductivity type and a second semiconductor region of a second conductivity type opposite said first conductivity type adjacent to said first semiconductor region, said method comprising the steps of: forming a first implant mask having a first portion and a second portion over said substrate, said first portion overlying a first portion of said first semiconductor region and said second portion overlying said second semiconductor region; performing a first high energy implantation wherein first conductivity type impurities pass through said first portion of said first implant mask to form a third semiconductor region in said first portion of said first semiconductor region; stripping said first implant mask; forming a second implant mask having a first portion overlying a first portion of said second semiconductor region and a second portion overlying said first semiconductor region; and performing a second high energy implantation wherein second conductivity type impurities pass through said first portion of said second implant mask to form a fourth semiconductor region in said first portion of said second semiconductor region.
Claim 28
Dependent Claim
37 words
The method of claim 19 wherein, during said step of performing said first high energy implantation, first conductivity type impurities are implanted into a second portion of said first semiconductor region to form a fifth semiconductor region.
Claim 29
Dependent Claim
20 words
The method of claim 20 wherein said third semiconductor region and said fifth semiconductor region have substantially uniform dopant concentrations.
Claim 30
Dependent Claim
37 words
The method of claim 20 wherein, during said step of performing said second high energy implantation, second conductivity type impurities are implanted into a second portion of said second semiconductor region to form a sixth semiconductor region.
Claim 31
Dependent Claim
20 words
The method of claim 22 wherein said fourth semiconductor region and said sixth semiconductor region have substantially uniform dopant concentrations.
Claim 32
Independent Claim
123 words
A method of forming a semiconductor device comprising the steps of: forming a mask over a semiconductor substrate, said mask having an edge which defines a first portion of said semiconductor substrate which is covered by said mask and a second portion of said semiconductor substrate which is not covered by said mask, wherein a first portion of said mask adjacent to said edge has a first permeability to implanted ions and a second portion of said mask laterally separated from said edge has a second permeability to implanted ions, said first permeability being greater than said second permeability; and selectively implanting impurity ions along a side boundary of a well region of said semiconductor substrate through said first portion of said mask.
Claim 33
Independent Claim
123 words
A method of forming a semiconductor device comprising the steps of: forming a mask over a semiconductor substrate, said mask having an edge which defines a first portion of said semiconductor substrate which is covered by said mask and a second portion of said semiconductor substrate which is not covered by said mask, wherein a first portion of said mask adjacent to said edge has a first permeability to implanted ions and a second portion of said mask laterally separated from said edge has a second permeability to implanted ions, said first permeability being greater than said second permeability; and selectively implanting impurity ions along a side boundary of a well region of said semiconductor substrate through said first portion of said mask.
Claim 34
Independent Claim
110 words
A method of forming a semiconductor device from a substrate comprising the steps of: forming a mask over a top surface of said substrate, said mask covering a first portion of said substrate and leaving a second portion exposed; performing a first ion implantation wherein first impurity ions enter said second portion thereby forming a first semiconductor region; and performing a second ion implantation wherein said impurity ions pass through a first portion of said mask and wherein said impurity ions enter said second portion of said substrate thereby forming a second semiconductor region having a substantially uniform dopant concentration greater than a dopant concentration of said first semiconductor region.
Claim 35
Independent Claim
110 words
A method of forming a semiconductor device from a substrate comprising the steps of: forming a mask over a top surface of said substrate, said mask covering a first portion of said substrate and leaving a second portion exposed; performing a first ion implantation wherein first impurity ions enter said second portion thereby forming a first semiconductor region; and performing a second ion implantation wherein said impurity ions pass through a first portion of said mask and wherein said impurity ions enter said second portion of said substrate thereby forming a second semiconductor region having a substantially uniform dopant concentration greater than a dopant concentration of said first semiconductor region.
Claim 36
Dependent Claim
25 words
The method of claim 25 wherein, during said step of performing said first ion implantation, said first impurity ions do not pass through said mask.
Claim 37
Dependent Claim
35 words
The method of claim 25 wherein said step of performing said second ion implantation is performed with an implant energy greater than an implant energy used during said step of performing said first ion implantation.
Claim 38
Dependent Claim
17 words
The method of claim 25 wherein said second semiconductor region is continuous with said first semiconductor region.
Claim 39
Dependent Claim
20 words
The method of claim 28 wherein said first semiconductor region and said second semiconductor region have a first conductivity type.
Claim 40
Dependent Claim
18 words
The method of claim 29 wherein said substrate has a second conductivity type opposite said first conductivity type.
Claim 41
Dependent Claim
27 words
The method of claim 25 wherein, during said step of performing said first ion implantation, said first impurity ions pass through said first portion of said mask.
References Cited (Backward Citations)
US4346512A
Cited
US4710477A
Cited
US4947227A
Cited
US4721686A
Cited
EP0250722A2
Cited
US4920066A
Cited
US5247200A
Cited
US4975764A
Cited
US5408125A
Cited
US5679586A
Cited
US5028556A
Cited
US5362981A
Cited
US5501993A
Cited
US5744372A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2003-01-24 | 2003-07-26 | 2004-01-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-01-24 | 2007-07-26 | 2008-01-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-01-24 | 2011-07-26 | 2012-01-25 | $7700.00 | Window Closed / Lapsed |