US5135884A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of producing isoplanar isolated active regions
Assignee: STMicroelectronics lnc USA
•
Filing: 1991-03-28
•
Granted: 1992-08-04
•
Expires: 2011-03-28
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 O. Miller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 04:47
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: 34
Claim 1
Independent Claim
96 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 to create sidewalls having a (111) crystal orientation and to form openings exposing a portion of the underlying substrate; forming a second masking layer in the openings; anodically porifying the first epitaxial layer; oxidizing the porified first epitaxial layer; removing the second masking layer; and, forming a second epitaxial layer in the openings.
Claim 2
Independent Claim
96 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 to create sidewalls having a (111) crystal orientation and to form openings exposing a portion of the underlying substrate; forming a second masking layer in the openings; anodically porifying the first epitaxial layer; oxidizing the porified first epitaxial layer; removing the second masking layer; and, forming a second epitaxial layer in the openings.
Claim 3
Dependent Claim
15 words
The method of claim 1, wherein a p-type dopant has been implanted into the substrate.
Claim 4
Dependent Claim
16 words
The method of claim 1, wherein the first epitaxial layer is doped with an n-type dopant.
Claim 5
Dependent Claim
19 words
The method of claim 1, wherein the first masking layer is removed after the first epitaxial layer is etched.
Claim 6
Dependent Claim
19 words
The method of claim 1, wherein the first masking layer is removed after the first epitaxial layer is anodized.
Claim 7
Dependent Claim
13 words
The method of claim 1, wherein the first masking layer is silicon dioxide.
Claim 8
Dependent Claim
13 words
The method of claim 1, wherein the first masking layer is silicon nitride.
Claim 9
Dependent Claim
13 words
The method of claim 1, wherein the second masking layer is silicon nitride.
Claim 10
Dependent Claim
16 words
The method of claim 1, wherein the crystal orientation of the substrate is the (100) plane.
Claim 11
Dependent Claim
13 words
The method of claim 1, wherein the etching step is an anisotropic etch.
Claim 12
Dependent Claim
11 words
The method of claim 10, wherein the anisotropic etchant is EDP.
Claim 13
Dependent Claim
14 words
The method of claim 1, wherein the etching step is a combination wet/dry etch.
Claim 14
Dependent Claim
13 words
The method of claim 12, further comprising the step of passivating the sidewalls.
Claim 15
Dependent Claim
13 words
The method of claim 13, wherein the passivating step is a boron implant.
Claim 16
Independent Claim
48 words
A method of producing isoplanar isolated regions in an integrated circuit comprising the steps of: forming a first epitaxial layer over a substrate; patterning the first epitaxial layer to form isolated regions; forming a second epitaxial layer in between the isolated regions; and, oxidizing the first epitaxial layer.
Claim 17
Independent Claim
48 words
A method of producing isoplanar isolated regions in an integrated circuit comprising the steps of: forming a first epitaxial layer over a substrate; patterning the first epitaxial layer to form isolated regions; forming a second epitaxial layer in between the isolated regions; and, oxidizing the first epitaxial layer.
Claim 18
Dependent Claim
19 words
The method of claim 15, wherein the first epitaxial layer is anodized before the second epitaxial layer is formed.
Claim 19
Dependent Claim
35 words
The method of claim 16, wherein a second masking layer of silicon nitride is deposited between the isolated regions before anodization of the first epitaxial layer and removed after anodization of the first epitaxial layer.
Claim 20
Dependent Claim
19 words
The method of claim 15, wherein the first epitaxial layer is anodized after the second epitaxial layer is formed.
Claim 21
Dependent Claim
24 words
The method of claim 15, wherein a first masking layer is formed over the first epitaxial layer before the first epitaxial layer is patterned.
Claim 22
Dependent Claim
19 words
The method of claim 19, wherein the first masking layer is removed after the firs epitaxial layer is patterned.
Claim 23
Dependent Claim
16 words
The method of claim 15, wherein the crystal orientation of the substrate is the (100) plane.
Claim 24
Dependent Claim
24 words
The method of claim 21, wherein the etching step is an anisotropic etch which produces sidewalls having the crystal orientation of the (111) plane.
Claim 25
Independent Claim
70 words
A method of producing isoplanar isolated regions in an integrated circuit comprising the steps of: forming a first epitaxial layer over a substrate; patterning and etching the first epitaxial layer to form isolated regions having sidewalls which have a (111) crystal orientation; oxidizing the first epitaxial layer; and, forming a second epitaxial layer in between the isolated regions; wherein the first epitaxial layer is anodically porified before the oxidizing step.
Claim 26
Independent Claim
70 words
A method of producing isoplanar isolated regions in an integrated circuit comprising the steps of: forming a first epitaxial layer over a substrate; patterning and etching the first epitaxial layer to form isolated regions having sidewalls which have a (111) crystal orientation; oxidizing the first epitaxial layer; and, forming a second epitaxial layer in between the isolated regions; wherein the first epitaxial layer is anodically porified before the oxidizing step.
Claim 27
Independent Claim
106 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 firs masking layer; etching the first epitaxial layer to create sidewalls having a (111) crystal orientation and to form openings exposing a portion of the substrate; forming a polymer layer over the surface of the wafer; etching the polymer layer to expose the first masking layer; removing the first masking layer; anodically porifying the first epitaxial layer; oxidizing the first epitaxial layer; and, forming a second epitaxial layer in the openings.
Claim 28
Independent Claim
106 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 firs masking layer; etching the first epitaxial layer to create sidewalls having a (111) crystal orientation and to form openings exposing a portion of the substrate; forming a polymer layer over the surface of the wafer; etching the polymer layer to expose the first masking layer; removing the first masking layer; anodically porifying the first epitaxial layer; oxidizing the first epitaxial layer; and, forming a second epitaxial layer in the openings.
Claim 29
Dependent Claim
18 words
The method of claim 24, wherein the polymer layer is removed after anodically porifying the first epitaxial layer.
Claim 30
Dependent Claim
18 words
The method of claim 24, wherein a second masking layer is formed before the polymer layer is formed.
Claim 31
Dependent Claim
13 words
The method of claim 26, wherein the second masking layer is silicon nitride.
Claim 32
Dependent Claim
21 words
The method of claim 26, wherein the second masking layer is a layer of silicon nitride over a layer of oxide.
Claim 33
Dependent Claim
18 words
The method of claim 26, wherein the polymer layer is removed before anodically porifying the first epitaxial layer.
Claim 34
Dependent Claim
18 words
The method of claim 26, wherein the polymer layer is removed after anodically porifying the first epitaxial layer.
References Cited (Backward Citations)
JPS53144690A
Cited
JPS55134946A
Cited
JPS5823431A
Cited
US4400411A
Cited
JPS59134819A
Cited
US4628591A
Cited
JPS61170018A
Cited
JPS61203632A
Cited
WO1987001239A1
Cited
US4810667A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-08-04 | 1996-02-03 | 1996-08-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-08-04 | 2000-02-03 | 2000-08-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-08-04 | 2004-02-03 | 2004-08-04 | $7700.00 | Window Closed / Lapsed |