USH1137H
Expired / Lapsed
US
⏱️ 0.0 years remaining
Wafer bonding technique for dielectric isolation processing
Assignee: AT&T Inc
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Filing: 1990-11-05
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Granted: 1993-02-02
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Expires: 2010-11-05
Abstract
Abstract A process for forming a dielectrically isolated wafer is disclosed. In particular, the conventional process is altered to replace the step of growing the thick polysilicon handle layer with the steps of growing a relatively thin conformal coating layer and bonding a single crystal wafer thereto. The wafer will become the substrate of the final device structure. The process of bonding is considered to be more efficient and economical than the prior art polysilicon growth process. Additionally, the tub structures of the wafer bonding process may be exposed to a somewhat lower temperature (for bonding) for shorter period of time than the tub regions of the conventional thick polysilicon DI structures. Therefore, the tub regions will exhibit superior qualities (e.g., less stress, fewer crystal defects) when compared with those formed with the conventional polysilicon growth technique. The wafer bonding process may be utilized with virtually and tub structure since the bonding step occurs subsequent to any tub fabrication processes.
Inventors
- 👤 William G. Easter
- 👤 Richard H. Shanaman, III
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 22:11
CPC Classifications
H; H10; H10P; H10P90/00; H10P90/19; H10P90/1904; H10P90/1906; H10W; H10W10/00; H10W10/01; H10W10/011; H10W10/019; H10W10/061; H10W10/10; H10W10/181; H10P90/1914; H10W10/014; H10W10/17
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
61 words
In a method of forming a dielectrically isolated wafer, replacing the step of growing a polysilicon handle layer with the following steps: a) forming a layer of conformal material of a thickness sufficient to fill any voids on the wafer surface; b) planarizing the conformal layer of step a); c) bonding a silicon substrate to the planarized layer of step b).
Claim 2
Dependent Claim
61 words
In a method of forming a dielectrically isolated wafer, replacing the step of growing a polysilicon handle layer with the following steps: a) forming a layer of conformal material of a thickness sufficient to fill any voids on the wafer surface; b) planarizing the conformal layer of step a); c) bonding a silicon substrate to the planarized layer of step b).
Claim 3
Dependent Claim
21 words
In the method of claim 1, when performing step b), planarizing the conformal layer until an underlying dielectric layer is exposed.
Claim 4
Dependent Claim
23 words
In the method of claim 1, when performing step b), planarizing the conformal layer such that an underlying dielectric layer is not exposed.
Claim 5
Dependent Claim
54 words
In the method of claim 1, when performing step c), utilizing the following steps: c 1 ) attaching a silicon substrate to the planarized conformal layer with a force sufficient to cause adhesion; and c 2 ) heating the adhered structure for a time and at a temperature sufficient to form a permanent bond.
Claim 6
Dependent Claim
27 words
In the method of claim 4, when performing step c 2 , heating the structure for at least two hours at a temperature of approximately 1000° C.
Claim 7
Dependent Claim
14 words
In the method of claim 1, when performing step a), growing a polysilicon layer.
Claim 8
Dependent Claim
22 words
In the method of claim 6, growing a polysilicon layer of a thickness at least twice that of an associated tub region.
Claim 9
Dependent Claim
15 words
In the method of claim 1, when performing step a), forming a silicon nitride layer.
Claim 10
Independent Claim
119 words
A method of forming a dielectrically isolated structure, the method comprising the steps of: a) providing a first silicon substrate; b) etching said first substrate to delineate locations of predetermined tub regions; c) forming a dielectric layer over the etched surface formed in step b) to form a dielectric layer sufficient to provide electrical isolation in the final dielectrically isolated structure; d) forming a conformal layer over the dielectric layer of step c), the conformal layer being of a thickness sufficient to at least fill the etched tub regions; e) bonding a second silicon substrate to the planarized conformal layer of step d); and f) removing a portion of the first silicon substrate sufficient to expose the tub region.
Claim 11
Independent Claim
119 words
A method of forming a dielectrically isolated structure, the method comprising the steps of: a) providing a first silicon substrate; b) etching said first substrate to delineate locations of predetermined tub regions; c) forming a dielectric layer over the etched surface formed in step b) to form a dielectric layer sufficient to provide electrical isolation in the final dielectrically isolated structure; d) forming a conformal layer over the dielectric layer of step c), the conformal layer being of a thickness sufficient to at least fill the etched tub regions; e) bonding a second silicon substrate to the planarized conformal layer of step d); and f) removing a portion of the first silicon substrate sufficient to expose the tub region.
Claim 12
Dependent Claim
15 words
The method of claim 9 wherein in performing step d), the conformal layer is planarized.
Claim 13
Dependent Claim
18 words
The method of claim 10 wherein the conformal layer is planarized until the underlying dielectric layer is exposed.
Claim 14
Dependent Claim
56 words
The method of claim 9 wherein in performing step e), the following steps are performed: e 1 ) attaching the second silicon substrate to the conformal layer with a force sufficient to cause adhesion; and e 2 ) heating the adhered structure for a time and at a temperature sufficient to form a permanent bond therebetween.
Claim 15
Dependent Claim
27 words
The method of claim 12 wherein in performing step e 2 , heating the structure for at least two hours at a temperature of approximately 1000° C.
Claim 16
Dependent Claim
15 words
The method of claim 9 wherein in performing step d), a polysilicon layer is formed.
Claim 17
Dependent Claim
16 words
The method of claim 9 wherein in performing step d), a silicon nitride layer is formed.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-02-02 | 1996-08-03 | 1997-02-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-02-02 | 2000-08-03 | 2001-02-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-02-02 | 2004-08-03 | 2005-02-02 | $7700.00 | Window Closed / Lapsed |