EP0506473A2
Expired / Lapsed
EP
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Method of producing isoplanar isolated active regions
Assignee: STMicroelectronics lnc USA
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Filing: 1992-03-27
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Granted: —
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Expires: 2012-03-27
Abstract
Abstract A method is provided for forming isoplanar isolated regions in an integrated circuit, and an integrated circuit formed according to the same. According to a first disclosed embodiment, a first epitaxial layer is formed over a substrate, the substrate having a (100) crystal orientation. A first masking layer is formed over the first epitaxial layer. The first masking layer is patterned and the first epitaxial layer is etched to form openings. The sidewalls of these openings have a (111) crystal orientation. The first masking layer is then removed and a second masking layer is formed in the openings. The first epitaxial layer is anodized and oxidized. The second masking layer is removed and a second epitaxial layer is formed in the openings. According to an alternate embodiment, after the first epitaxial layer is anodized, the second epitaxial layer is formed in the openings and the first epitaxial layer is then oxidized. According to a further alternate embodiment, the first epitaxial layer is anodized and oxidized after the second epitaxial layer is formed in the openings.
Inventors
- 👤 Robert Otis Miller
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-23 20:30
CPC Classifications
H; H10; H10P; H10P90/00; H10P90/19; H10P90/1904; H10P90/1906; H10P90/191; H10W; H10W10/00; H10W10/01; H10W10/011; H10W10/018; H10W10/10; H10W10/181
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
52 words
A method of producing isoplanar isolated regions in an integrated circuit comprising the steps of: (a) forming a first epitaxial layer over a substrate; (b) patterning the first epitaxial layer to form isolated regions; (c) forming a second epitaxial layer in between the isolated regions; and (d) oxidizing the first epitaxial layer.
Claim 2
Independent Claim
75 words
A method of producing isoplanar isolated regions in an integrated circuit comprising the steps of: forming a first epitaxial layer over a substrate; forming a first masking layer over the first epitaxial layer; patterning the first masking layer; etching the first epitaxial layer; forming a second masking layer in the openings; anodizing the first epitaxial layer; oxidizing the first epitaxial layer; removing the second masking layer; and, forming a second epitaxial layer in the openings.
Claim 3
Dependent Claim
15 words
A method as claimed in claim 1 wherein step (d) is performed before step (c).
Claim 4
Independent Claim
80 words
A method of producing isoplanar isolated regions in an integrated circuit comprising the steps of: forming a first epitaxial layer over a substrate; forming a first masking layer over the first epitaxial layer; patterning the first masking layer; etching the first epitaxial layer; forming a polymer layer over the surface of the wafer; etching the polymer; removing the first masking layer; anodizing the first epitaxial layer; oxidizing the first epitaxial layer; and forming a second epitaxial layer in the openings.
Claim 5
Dependent Claim
35 words
An integrated circuit, comprising: a substrate; and, epitaxial regions disposed over the substrate separated by oxide regions wherein the epitaxial regions having an inverted trapezoidal volume are wider at the top than at the bottom.
Claim 6
Independent Claim
22 words
The method of any one of claims 1, 2, 3 or 4, wherein a p-type dopant has been implanted into the substrate.
Claim 7
Independent Claim
23 words
The method of any one of claims 1, 2, 3 or 4, wherein the first epitaxial layer is doped with an n-type dopant.
Claim 8
Dependent Claim
19 words
The method of claim 1, wherein the first epitaxial layer is anodized before the second epitaxial layer is formed.
Claim 9
Dependent Claim
19 words
The method of claim 1, wherein the first epitaxial layer is anodized after the second epitaxial layer is formed.
Claim 10
Dependent Claim
19 words
The method of claim 2, wherein the first masking layer is removed after the first epitaxial layer is etched.
Claim 11
Dependent Claim
19 words
The method of claim 2, wherein the first masking layer is removed after the first epitaxial layer is anodized.
Claim 12
Dependent Claim
21 words
The method of claim 2 or 4, wherein the first masking layer is either silicon dioxide (SiO₂) or silicon nitride (Si₃N₄).
Claim 13
Dependent Claim
28 words
The method of claim 8, wherein a second masking layer is deposited before anodization of the first epitaxial layer and removed after anodization of the first epitaxial layer.
Claim 14
Dependent Claim
18 words
The method of claim 4, wherein a second masking layer is formed before the polymer layer is formed.
Claim 15
Dependent Claim
27 words
The method of claim 2 or 4, wherein the second masking layer is nitride (Si₃N₄) or a layer of silicon nitride (Si₃N₄) over a layer of oxide.
Claim 16
Dependent Claim
26 words
The method of claim 1, 2 or 3 or the integrated circuit of claim 5, wherein the crystal orientation of the substrate is the (100) plane.
Claim 17
Dependent Claim
21 words
The integrated circuit of claim 15, wherein the sidewalls of the epitaxial regions have the crystal orientation of the (111) plane.
Claim 18
Dependent Claim
31 words
The method of claim 16, wherein the etching step of claim 2 or the patterning step of claim 1 or 3 creates sidewalls having the crystal orientation of the (111) plane.
Claim 19
Dependent Claim
28 words
The method of claim 15, wherein the etching or patterning step is an anisotropic etch, preferably a combination wet/dry etch, which produces sidewalls having a (111) crystal orientation.
Claim 20
Dependent Claim
11 words
The method of claim 19, wherein the anisotropic etchant is EDP.
Claim 21
Dependent Claim
20 words
The method of claim 19 or 20, further comprising the step of passivating the sidewalls, preferably using a boron implant.
Claim 22
Dependent Claim
17 words
The method of claim 4, wherein the polymer layer is removed after anodizing the first epitaxial layer.
Claim 23
Dependent Claim
24 words
The method of claim 14, wherein the polymer layer is removed before anodizing the first epitaxial layer if the second masking layer is formed.
Claim 24
Dependent Claim
24 words
The method of claim 14, wherein the polymer layer is removed after anodizing the first epitaxial layer if the second masking layer is formed.
References Cited (Backward Citations)
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