US5670431A
Expired / Lapsed
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Method of forming an ultra thin dielectric film for a capacitor
Assignee: Taiwan Semiconductor Manufacturing Co TSMC Ltd
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Filing: 1996-06-13
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Granted: 1997-09-23
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Expires: 2016-06-13
Abstract
Abstract The present invention provides a method of forming a ultra thin silicon nitride/silicon oxide (NO) dielectric layer over a polysilicon capacitor electrode formed adjacent to a silicon oxide insulating layer. First, a HF in-situ vapor clean is used to clean the polysilicon electrode and oxide insulating layers. A first silicon nitride (SiN) layer is then selectively deposited over the electrode. Next, the substrate is exposed to air. This grows a native oxide layer over the first silicon nitride layer and the insulating layer. Next, a second SiN layer is formed over the first silicon nitride layer, the insulating layer and the interface between the polysilicon electrode and the insulating layer. A thin oxide dielectric layer is grown over the second silicon nitride layer to complete the (NO) capacitor dielectric layer. The method of the present invention is an inexpensive process that provides an oxide free interface between the polysilicon and oxide layers. The method produces an uniform ultra thin silicon nitride/silicon oxide dielectric layer over a polysilicon electrode.
Inventors
- 👤 Julie Huanga
- 👤 Mong-Song Liang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:57
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/60; H10P14/65; H10P14/6502; H10P14/6504; H10P14/63; H10P14/6326; H10P14/6328; H10P14/6334; H10P14/69; H10P14/692; H10P14/6921; H10P14/69215; H10P14/694; H10P14/6943; H10P14/69433
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
133 words
A method of fabricating an uniform thin silicon nitride layer over a polysilicon layer and over an adjacent insulating layer, said polysilicon layer and said insulating layer join at an interface, the method comprises the steps of: a) under a non-oxidizing environment, cleaning the surface of said polysilicon layer with an HF vapor; b) under a non-oxidizing environment, selectively forming a first silicon nitride layer over said polysilicon layer and said interface; c) subjecting the semiconductor substrate to air thereby growing a native oxide over the said insulating layer and said first silicon nitride layer; d) under a reduced pressure, forming a second silicon nitride layer over said first silicon nitride layer and said native oxide layer, said second nitride layer completely covering said interface between said polysilicon layer and said insulating layer.
Claim 2
Independent Claim
133 words
A method of fabricating an uniform thin silicon nitride layer over a polysilicon layer and over an adjacent insulating layer, said polysilicon layer and said insulating layer join at an interface, the method comprises the steps of: a) under a non-oxidizing environment, cleaning the surface of said polysilicon layer with an HF vapor; b) under a non-oxidizing environment, selectively forming a first silicon nitride layer over said polysilicon layer and said interface; c) subjecting the semiconductor substrate to air thereby growing a native oxide over the said insulating layer and said first silicon nitride layer; d) under a reduced pressure, forming a second silicon nitride layer over said first silicon nitride layer and said native oxide layer, said second nitride layer completely covering said interface between said polysilicon layer and said insulating layer.
Claim 3
Dependent Claim
14 words
The method of claim 1 wherein said insulating layer is formed of silicon oxide.
Claim 4
Dependent Claim
26 words
The method of claim 1 wherein the non-oxidizing environment in steps (a) and (b) comprises a non-oxygen containing gas mixture at a pressure below 760 torrs.
Claim 5
Dependent Claim
29 words
The method of claim 1 which further includes growing a silicon oxide dielectric layer over said second silicon nitride layer thereby forming a silicon nitride/silicon oxide (NO) dielectric layer.
Claim 6
Dependent Claim
41 words
The method of claim 1 which further includes growing a silicon oxide dielectric layer over said second silicon nitride layer, said silicon oxide dielectric layer formed by a wet oxidation with a temperature in a range between 800° and 850° C.
Claim 7
Dependent Claim
21 words
The method of claim 1 wherein said insulating layer is formed by a chemical vapor deposition (CVD) process using tetraethylorthosilicate (TEOS).
Claim 8
Dependent Claim
38 words
The method of claim 1 wherein said polysilicon layer has a thickness in a range of between about 2000 and 5000 Å and an impurity concentration in a range of between about 1E19 and 1E20 atoms/cm 3 .
Claim 9
Dependent Claim
25 words
The method of claim 1 wherein said polysilicon layer has an impurity concentration in a range of between about 5E16 and 2E16 atoms/cm 3 .
Claim 10
Dependent Claim
76 words
The method of claim 1 wherein said first silicon nitride layer is formed using a LPCVD process with dichlorosilane and ammonia at reduced pressure at reduced pressure, said first silicon nitride layer formed at a pressure in a range between about 30 and 80 Pa, and at a temperature in a range between about 600° and 800° C. and said first silicon nitride layer having a thickness in a range between about 15 and 30 Å.
Claim 11
Dependent Claim
78 words
The method of claim 1 wherein said second silicon nitride layer is formed using a low pressure chemical vapor deposition (LPCVD) process with dichlorosilane and ammonia at reduced pressure, said second silicon nitride layer formed at a pressure in a range between about 30 and 80 Pa, and at a temperature in a range between about 600° and 800° C. and said second silicon nitride layer having a thickness in a range between about 30 and 40 Å.
Claim 12
Dependent Claim
24 words
The method of claim 1 wherein the method is performed in-situ in a HF cleaning and LPCVD furnace tool having a wafer transportation system.
Claim 13
Independent Claim
123 words
A method of forming an ultra thin dielectric film for a capacitor on a semiconductor substrate, said substrate having two spaced gates structures with a source region therebetween, an insulating layer overlying portions of said gate structures, and said substrate having a bottom electrode comprised of polysilicon overlying portions of said insulating layer, said gate structures and said source region, the method comprising: a) cleaning the surfaces of said bottom electrode with a HF vapor; b) selectively forming a first silicon nitride layer over said bottom electrode; c) subjecting the semiconductor substrate to air thereby growing a native oxide over the said insulating layer and said first silicon nitride layer; and d) forming a second silicon nitride layer over said native oxide layer.
Claim 14
Independent Claim
123 words
A method of forming an ultra thin dielectric film for a capacitor on a semiconductor substrate, said substrate having two spaced gates structures with a source region therebetween, an insulating layer overlying portions of said gate structures, and said substrate having a bottom electrode comprised of polysilicon overlying portions of said insulating layer, said gate structures and said source region, the method comprising: a) cleaning the surfaces of said bottom electrode with a HF vapor; b) selectively forming a first silicon nitride layer over said bottom electrode; c) subjecting the semiconductor substrate to air thereby growing a native oxide over the said insulating layer and said first silicon nitride layer; and d) forming a second silicon nitride layer over said native oxide layer.
Claim 15
Dependent Claim
14 words
The method of claim 12 wherein said insulating layer is formed of silicon oxide.
Claim 16
Dependent Claim
20 words
The method of claim 12 which further includes forming a silicon oxide dielectric layer over said second silicon nitride layer.
Claim 17
Dependent Claim
36 words
The method of claim 12 which further includes forming a silicon oxide dielectric layer over the second silicon nitride layer and forming a top electrode layer over said silicon oxide dielectric layer thereby forming a capacitor.
Claim 18
Dependent Claim
58 words
The method of claim 12 which further includes forming a silicon oxide dielectric layer over said second silicon nitride layer, said silicon oxide dielectric layer having a thickness in a range between 5 and 10 Å, and said silicon oxide dielectric layer formed by a wet oxidation with a temperature in a range between 800° and 900° C.
Claim 19
Dependent Claim
18 words
The method of claim 12 wherein said insulating layer is formed by a CVD process using tetraethylorthosilicate (TEOS).
Claim 20
Dependent Claim
38 words
The method of claim 12 wherein said bottom electrode has a thickness in a range of between about 2000 and 5000 Å and an impurity concentration in a range of between about 1E19 and 1E20 atoms/cm 3 .
Claim 21
Dependent Claim
76 words
The method of claim 12 wherein said first silicon nitride layer is formed using a LPCVD process with dichlorosilane and ammonia at reduced pressure at reduced pressure, said first silicon nitride layer formed at a pressure in a range between about 30 and 80 Pa, and at a temperature in a range between about 600° and 800° C., and said first silicon nitride layer having a thickness in a range between about 15 and 30 Å.
Claim 22
Dependent Claim
73 words
The method of claim 12 wherein said second silicon nitride layer is formed using a LPCVD process with dichlorosilane and ammonia at reduced pressure, said first silicon nitride layer formed at a pressure in a range between about 30 and 80 Pa, and at a temperature in a range between about 600° and 800° C. and said second silicon nitride layer having a thickness in a range between about 30 and 40 Å.
References Cited (Backward Citations)
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