US5641380A
Expired / Lapsed
US
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Method for fabricating a semiconductor device
Assignee: Semiconductor Energy Laboratory Co Ltd
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Filing: 1995-12-01
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Granted: 1997-06-24
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Expires: 2015-12-01
Abstract
Abstract There is proposed a process for performing (quasi-) anisotropic etching on a silicon-based material without using plasma. The process consists of irradiating a polycrystalline or single-crystalline silicon film or substrate with a beam of accelerated hydrogen ions, silicon ions, or rare gas ions, so that the crystalline silicon is made amorphous. Then, the amorphous silicon is placed in an atmosphere of fluorinated halogen. Since the etching rate of fluorinated halogen for amorphous silicon is greater than that for polycrystalline or single-crystalline silicon, etching takes place selectively at the area which has been irradiated with a beam of accelerated hydrogen ions, silicon ions, or rare gas ions. The selective etching permits (quasi-) anisotropic etching instead of sideward isotropic etching.
Inventors
- 👤 Shunpei Yamazaki
- 👤 Hideomi Suzawa
- 👤 Yasuhiko Takemura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 06:35
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/021; H10D30/0223; H10D30/0227; H10P; H10P50/00; H10P50/20; H10P50/26; H10P50/264; H10P50/266; H10P50/267; H10P50/268
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
52 words
A method for fabricating a semiconductor device comprising the steps of: forming a crystalline silicon film on a substrate; selectively forming an amorphous portion in said crystalline silicon film; and preferentially etching said amorphous portion; wherein an etching rate of said amorphous portion is larger than that of said crystalline silicon film.
Claim 2
Independent Claim
52 words
A method for fabricating a semiconductor device comprising the steps of: forming a crystalline silicon film on a substrate; selectively forming an amorphous portion in said crystalline silicon film; and preferentially etching said amorphous portion; wherein an etching rate of said amorphous portion is larger than that of said crystalline silicon film.
Claim 3
Dependent Claim
27 words
A method of claim 1 wherein the selective formation of said amorphous portion is performed by irradiating ions with a mask formed on said crystalline silicon film.
Claim 4
Dependent Claim
19 words
A method of claim 2 wherein said ions is selected from hydrogen ions, silicon ions, and rare gas ions.
Claim 5
Dependent Claim
21 words
A method of claim 1 wherein the preferential etching of said amorphous portion is performed in an atmosphere of fluorinated halogen.
Claim 6
Dependent Claim
28 words
A method of claim 4 wherein hydrogen ions is used as said irradiating ions, the concentration of said hydrogen ions being more than 1×10 21 atoms/cm 3 .
Claim 7
Dependent Claim
22 words
A method of claim 4 wherein the etching rate is controlled according to concentration, temperature or flow rate of said fluorinated halogen.
Claim 8
Dependent Claim
30 words
A method claim 1 wherein said preferential etching of said amorphous portion is performed with etching of said crystalline silicon film surrounding said amorphous portion, whereby quasi-anisotropic etching is performed.
Claim 9
Dependent Claim
26 words
A method of claim 1 wherein said substrate is an insulating substrate and said semiconductor devise is a thin film transistor formed on said insulating substrate.
Claim 10
Dependent Claim
31 words
A method of claim 1 wherein said crystalline silicon film is formed by thermally annealing an amorphous silicon comprising at least one species selected from nickel, platinum, iron, cobalt, and palladium.
Claim 11
Independent Claim
85 words
A method for fabricating a semiconductor device comprising the steps of: forming a crystalline silicon interconnect on a substrate; forming a crystalline silicon film on said crystalline silicon interconnect; selectively forming an amorphous portion in said crystalline silicon film, thereby the amorphous portion and a crystalline silicon portion being formed in said crystalline silicon film, and preferentially etching said amorphous portion such that a side wall is formed at a side of said crystalline silicon interconnection, said side wall corresponding to said crystalline silicon portion.
Claim 12
Independent Claim
85 words
A method for fabricating a semiconductor device comprising the steps of: forming a crystalline silicon interconnect on a substrate; forming a crystalline silicon film on said crystalline silicon interconnect; selectively forming an amorphous portion in said crystalline silicon film, thereby the amorphous portion and a crystalline silicon portion being formed in said crystalline silicon film, and preferentially etching said amorphous portion such that a side wall is formed at a side of said crystalline silicon interconnection, said side wall corresponding to said crystalline silicon portion.
Claim 13
Dependent Claim
31 words
A method of claim 10 wherein the selective formation of said amorphous portion is performed by irradiating ions, a depth of the ion penetration being controlled by the ion accelerating voltage.
Claim 14
Dependent Claim
19 words
A method of claim 11 wherein the ion penetration reaches to the upper part of said crystalline silicon interconnect.
Claim 15
Dependent Claim
21 words
A method of claim 10 wherein the preferential etching of said amorphous portion is performed in an atmosphere of fluorinated halogen.
Claim 16
Dependent Claim
27 words
A method of claim 10 wherein an approximately triangular wall of crystalline silicon is formed on each side of said crystalline silicon interconnect by said preferential etching.
Claim 17
Dependent Claim
26 words
A method of claim 10 wherein said substrate is an insulating substrate and said semiconductor devise is a thin film transistor formed on said insulating substrate.
Claim 18
Dependent Claim
30 words
A method of claim 10 wherein said crystalline film is formed by thermally annealing an amorphous silicon comprising at least one species selected from nickel, platinum, iron, cobalt, and palladium.
Claim 19
Independent Claim
135 words
A method for fabricating a field-effect transistor comprising the steps of: forming a gate insulating film on a substrate; forming a central portion as a part of a gate electrode on said gate insulating film, said central portion comprising crystalline silicon; forming a lightly doped region in said substrate using said central portion as a mask; forming a crystalline silicon film on at least said central portion; selectively forming an amorphous portion in said crystalline silicon film, thereby the amorphous portion and a crystalline silicon portion being formed in said crystalline silicon film; and preferentially etching said amorphous portion such that a side wall as a part of said gate electrode is formed at a side of said central portion and over said lightly doped region, said side wall corresponding to said crystalline silicon portion.
Claim 20
Independent Claim
135 words
A method for fabricating a field-effect transistor comprising the steps of: forming a gate insulating film on a substrate; forming a central portion as a part of a gate electrode on said gate insulating film, said central portion comprising crystalline silicon; forming a lightly doped region in said substrate using said central portion as a mask; forming a crystalline silicon film on at least said central portion; selectively forming an amorphous portion in said crystalline silicon film, thereby the amorphous portion and a crystalline silicon portion being formed in said crystalline silicon film; and preferentially etching said amorphous portion such that a side wall as a part of said gate electrode is formed at a side of said central portion and over said lightly doped region, said side wall corresponding to said crystalline silicon portion.
Claim 21
Dependent Claim
21 words
A method of claim 17 wherein the preferential etching of said amorphous portion is performed in an atmosphere of fluorinated halogen.
Claim 22
Dependent Claim
30 words
A method of claim 17 wherein said crystalline film is formed by thermally annealing an amorphous silicon comprising at least one species selected from nickel, platinum, iron, cobalt, and palladium.
Claim 23
Dependent Claim
32 words
A method of claim 17 further comprising the following step of: performing ion implantation in order to source and drain regions using said central portion and said side wall as a mask.
References Cited (Backward Citations)
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