Patent US6274444B1 successfully refreshed from Google Patents.
US6274444B1
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for forming mosfet
Assignee: United Microelectronics Corp
•
Filing: 1999-08-10
•
Granted: 2001-08-14
•
Expires: 2019-08-10
Abstract
Abstract A method for forming a MOSFET is described. The feature of this invention is that an epitaxial silicon layer with device isolation structures is formed over a substrate, wherein each device isolation structure is made of oxide. The invention need not etch the substrate for forming a device isolation structure. As a result, the invention not only prevents stress and dislocation generation and avoids leakage current, but also provides an easily method for forming a device isolation structure.
Inventors
- 👤 Chuan-Fu Wang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 07:28
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/021; H10D30/027; H10D30/0278; H10D84/00; H10D84/01; H10D84/0123; H10D84/0126; H10D84/0151; H10D84/0156; H10D84/02; H10D84/03; H10D84/038
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
113 words
A method for forming a MOSFET, comprising the steps of: providing a substrate; forming a mask layer having an opening to expose the substrate; filling the opening with an epitaxial silicon layer, wherein a surface level of the epitaxial silicon layer is substantially the same as that of the mask layer; after filling the opening with the epetaxial silicon layer, removing the entire mask layer to expose the substrate; forming an oxide layer on the exposed substrate, wherein a surface level of the oxide layer is substantially the same as that of the epitaxial silicon layer; and forming a gate on the epitaxial silicon layer and source/drain regions in the epitaxial silicon layer.
Claim 2
Independent Claim
113 words
A method for forming a MOSFET, comprising the steps of: providing a substrate; forming a mask layer having an opening to expose the substrate; filling the opening with an epitaxial silicon layer, wherein a surface level of the epitaxial silicon layer is substantially the same as that of the mask layer; after filling the opening with the epetaxial silicon layer, removing the entire mask layer to expose the substrate; forming an oxide layer on the exposed substrate, wherein a surface level of the oxide layer is substantially the same as that of the epitaxial silicon layer; and forming a gate on the epitaxial silicon layer and source/drain regions in the epitaxial silicon layer.
Claim 3
Dependent Claim
13 words
The method of claim 1 , wherein the mask layer includes silicon nitride.
Claim 4
Dependent Claim
24 words
The method of claim 1 , further comprising a step of forming a pad oxide layer before the step of forming the mask layer.
Claim 5
Dependent Claim
18 words
The method of claim 1 , wherein the thickness of the epitaxial silicon layer is about 3000-4000 Å.
Claim 6
Dependent Claim
16 words
The method of claim 1 , wherein the oxide layer serves as a device isolation structure.
Claim 7
Independent Claim
128 words
A method for forming a MOSFET, comprising the steps of: forming a pad oxide layer and a silicon nitride layer on a substrate in sequence; forming an opening in the silicon nitride layer and the pad oxide layer to expose a portion of the substrate; filling the opening with an epitaxial silicon layer, wherein a surface level of the epitaxial silicon layer is substantially the same as that of the silicon nitride layer; after filling the opening with an epitaxial silicon layer, removing the entire silicon nitride layer to expose the pad oxide layer; forming an oxide layer over the substrate; planarizing the oxide layer to expose the epitaxial silicon layer; and forming a gate on the epitaxial silicon layer and source/drain regions in the epitaxial silicon layer.
Claim 8
Independent Claim
128 words
A method for forming a MOSFET, comprising the steps of: forming a pad oxide layer and a silicon nitride layer on a substrate in sequence; forming an opening in the silicon nitride layer and the pad oxide layer to expose a portion of the substrate; filling the opening with an epitaxial silicon layer, wherein a surface level of the epitaxial silicon layer is substantially the same as that of the silicon nitride layer; after filling the opening with an epitaxial silicon layer, removing the entire silicon nitride layer to expose the pad oxide layer; forming an oxide layer over the substrate; planarizing the oxide layer to expose the epitaxial silicon layer; and forming a gate on the epitaxial silicon layer and source/drain regions in the epitaxial silicon layer.
Claim 9
Dependent Claim
17 words
The method of claim 6 , wherein the step of planarizing the oxide layer includes etching back.
Claim 10
Dependent Claim
18 words
The method of claim 6 , wherein the step of planarizing the oxide layer includes chemical mechanical polishing.
Claim 11
Dependent Claim
18 words
The method of claim 6 , wherein the thickness of the epitaxial silicon layer is about 3000-4000 Å.
Claim 12
Dependent Claim
23 words
The method of claim 6 , wherein a residual oxide layer and a residual pad oxide layer serve as a device isolation structure.
Claim 13
Independent Claim
91 words
A method for forming a device isolation structure, comprising the steps of: forming a mask layer with an opening on a substrate to expose a portion of the substrate; filling the opening with an epitaxial silicon layer, wherein a surface level of the epitaxial silicon layer is substantially the same as that of the mask layer; removing the mask layer to expose the substrate; and forming an oxide layer on the substrate, wherein a surface level of the oxide layer is substantially the same as that of the epitaxial silicon layer.
Claim 14
Independent Claim
91 words
A method for forming a device isolation structure, comprising the steps of: forming a mask layer with an opening on a substrate to expose a portion of the substrate; filling the opening with an epitaxial silicon layer, wherein a surface level of the epitaxial silicon layer is substantially the same as that of the mask layer; removing the mask layer to expose the substrate; and forming an oxide layer on the substrate, wherein a surface level of the oxide layer is substantially the same as that of the epitaxial silicon layer.
Claim 15
Dependent Claim
13 words
The method of claim 11 , wherein the mask layer includes silicon nitride.
Claim 16
Dependent Claim
24 words
The method of claim 11 , further comprising a step of forming a pad oxide layer before the step of forming the mask layer.
Claim 17
Dependent Claim
18 words
The method of claim 11 , wherein the thickness of the epitaxial silicon layer is about 3000-4000 Å.
References Cited (Backward Citations)
US5959331A
Cited
US6010928A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2004-08-13 | 2005-02-12 | 2005-08-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-08-13 | 2009-02-12 | 2009-08-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-08-13 | 2013-02-12 | 2013-08-14 | $7700.00 | Window Closed / Lapsed |