US5750428A
Expired / Lapsed
US
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Self-aligned non-volatile process with differentially grown gate oxide thickness
Assignee: United Microelectronics Corp
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Filing: 1996-09-27
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Granted: 1998-05-12
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Expires: 2016-09-27
Abstract
Abstract A method of fabricating a novel electrically erasable programmable read only memory (EEPROM) cell for use in semiconductor memories is disclosed herein. Since the degree of ion implantation in the substrate determines the thichness of the silicon dioxide. The proper thickness of the silicon dioxide can be determined by considering the particular dopant to be used and degree of ion implantation, a 50-100 angstroms silicon dioxide is chosen for an arsenic or phosphorus dopant, 1E14-1E15 atoms/cm 2 , 100 KeV, ion implantation. A 150-350 angstroms silicon dioxide is chosen for an arsenic or phosphorus dopant, 1E11-1E13 atoms/cm 2 , 100 KeV, ion implantation. The method includes the steps of: forming an isolation layer on a substrate to serve as an isolation; doping ions to form a lightly-doped region in the substrate; patterning a photoresist on the substrate; doping an ions to form a highly-doped region in the substrate; removing the photoresist; oxidizing the substrate to form a gate oxide and a tunnel oxide simultaneously; and forming a first polysilicon layer on the gate oxide and the tunnel oxide.
Inventors
- 👤 Kuang-Yeh Chang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:10
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/021; H10D30/0411
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
157 words
A method of fabricating an electrically erasable programmable read only memory (EEPROM) on a semiconductor substrate, said method comprising the steps of: forming a plurality of isolation regions on said substrate to serve as isolations for an active region; performing a first ion implant to form a lightly-doped region in said active region, wherein said first ion implantation is a blanket ion implantation and is performed without a photo mask; patterning a photoresist on a portion of said active region; performing a second ion implant to form a plurality of highly-doped regions in said substrate by using said photoresist as a doping mask; removing said photoresist; oxidizing said substrate to form a gate oxide over said substrate and a tunnel oxide layer over the portion of said active region with differential thickness, simultaneously, wherein said gate oxide is thicker than said tunnel oxide; and forming a first polysilicon layer on said gate oxide and said tunnel oxide.
Claim 2
Independent Claim
157 words
A method of fabricating an electrically erasable programmable read only memory (EEPROM) on a semiconductor substrate, said method comprising the steps of: forming a plurality of isolation regions on said substrate to serve as isolations for an active region; performing a first ion implant to form a lightly-doped region in said active region, wherein said first ion implantation is a blanket ion implantation and is performed without a photo mask; patterning a photoresist on a portion of said active region; performing a second ion implant to form a plurality of highly-doped regions in said substrate by using said photoresist as a doping mask; removing said photoresist; oxidizing said substrate to form a gate oxide over said substrate and a tunnel oxide layer over the portion of said active region with differential thickness, simultaneously, wherein said gate oxide is thicker than said tunnel oxide; and forming a first polysilicon layer on said gate oxide and said tunnel oxide.
Claim 3
Dependent Claim
29 words
The method of claim 1, further comprising the steps of: forming an isolation layer on said first polysilicon layer; and forming a second polysilicon layer on said isolation layer.
Claim 4
Dependent Claim
19 words
The method of claim 1, wherein the dosage of said first ion implant is about 1E11-1E13 atoms/cm 2 .
Claim 5
Dependent Claim
17 words
The method of claim 3, wherein the energy of said first ion implant is about 100 KeV.
Claim 6
Dependent Claim
15 words
The method of claim 1, wherein the dopant of said first ion implant is arsenic.
Claim 7
Dependent Claim
16 words
The method of claim 1, wherein the dopant of said said first ion implant is phosphorus.
Claim 8
Dependent Claim
20 words
The method of claim 1, wherein said highly-doped region is formed to have a dosage about 1E14-1E15 atoms/cm 2 .
Claim 9
Dependent Claim
17 words
The method of claim 7, wherein the energy of said second ion implant is about 100 KeV.
Claim 10
Dependent Claim
15 words
The method of claim 1, wherein the dopant of said second ion implant is arsenic.
Claim 11
Dependent Claim
15 words
The method of claim 1, wherein the dopant of said second ion implant is phosphorus.
Claim 12
Dependent Claim
18 words
The method of claim 3, wherein said gate oxide is formed to have a thickness about 150-350 angstroms.
Claim 13
Dependent Claim
18 words
The method of claim 7, wherein said tunnel oxide is formed to have a thickness about 50-100 angstroms.
Claim 14
Dependent Claim
21 words
The method of claim 1, wherein the temperature of forming said gate oxide and said tunnel oxide is about 850°-1000° C.
Claim 15
Independent Claim
108 words
A method of fabricating an oxide layer with different thickness, said method comprising: performing a first ion implant to form a lightly-doped region in a semiconductor substrate, wherein said first ion implantation is a blanket ion implantation and is performed without a photo mask; patterning a photoresist on a portion of said substrate; performing a second ion implant to form highly-doped regions in said substrate by using said photoresist as a mask; removing said photoresist; and oxidizing said substrate to form a silicon oxide layer, thickness of the silicon oxide layer over the lightly-doped region being thinner than thickness of the silicon oxide layer over the highly-doped regions.
Claim 16
Independent Claim
108 words
A method of fabricating an oxide layer with different thickness, said method comprising: performing a first ion implant to form a lightly-doped region in a semiconductor substrate, wherein said first ion implantation is a blanket ion implantation and is performed without a photo mask; patterning a photoresist on a portion of said substrate; performing a second ion implant to form highly-doped regions in said substrate by using said photoresist as a mask; removing said photoresist; and oxidizing said substrate to form a silicon oxide layer, thickness of the silicon oxide layer over the lightly-doped region being thinner than thickness of the silicon oxide layer over the highly-doped regions.
Claim 17
Dependent Claim
15 words
The method of claim 14, wherein the dopant of said first ion implant is arsenic.
Claim 18
Dependent Claim
15 words
The method of claim 14, wherein the dopant of said first ion implant is phosphorus.
Claim 19
Dependent Claim
15 words
The method of claim 14, wherein the dopant of said second ion implant is arsenic.
Claim 20
Dependent Claim
15 words
The method of claim 14, wherein the dopant of said second ion implant is phosphorus.
Claim 21
Dependent Claim
21 words
The method of claim 14, wherein the temperature of forming said gate oxide and said tunnel oxide is about 850°-1000° C.
References Cited (Backward Citations)
US5393684A
Cited
US5429960A
Cited
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