Patent US6093607A successfully refreshed from Google Patents.
US6093607A
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Method of forming sharp beak of poly by oxygen/fluorine implant to improve erase speed for split-gate flash
Assignee: Taiwan Semiconductor Manufacturing Co TSMC Ltd
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Filing: 1998-01-09
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Granted: 2000-07-25
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Expires: 2018-01-09
Abstract
Abstract A method is provided for forming a short and sharp gate bird's beak in order to increase the erase speed of a split-gate flash memory. This is accomplished in two embodiments where in the first, fluorine is implanted in the first polysilicon layer to form the floating gate. It is disclosed here that the implanting of fluorine increases the oxidation rate of the polysilicon and because of the faster oxidation, the polygate bird's beak (GBB) that is formed attains a relatively short and sharp shape in comparison with conventional beaks. This has the attendant benefit of forming a relatively small memory cell, and the concomitant increase in the erase speed of the cell. In the second embodiment, oxygen is used with the same favorable results. A third embodiment discloses the structure of a split-gate flash memory cell having a sharp bird's beak.
Inventors
- 👤 Chia-Ta Hsieh
- 👤 Yai-Fen Lin
- 👤 Hong-Cheng Sung
- 👤 Di-Son Kuo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 03:41
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/60; H10D30/68; H10D30/6891; H10D64/00; H10D64/01; H10D64/031; H10D64/035
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
128 words
A method of forming sharp beak in a split-gate flash memory comprising the steps of: providing a semiconductor substrate; forming a gate oxide layer over said substrate; forming a first polysilicon layer over said gate oxide layer; forming a mask layer over said first polysilicon layer; patterning said mask layer to define a floating gate region in said first polysilicon layer; implanting fluorine ions in said floating gate region in said first polysilicon layer; removing said layer; forming a sharp gate 6 bird's beak (GBB) in said floating gate region; etching said first polysilicon layer to form said floating gate; forming an oxide layer over said floating gate; forming a second polysilicon layer over said oxide layer; and patterning said second polysilicon layer to form a control gate.
Claim 2
Independent Claim
128 words
A method of forming sharp beak in a split-gate flash memory comprising the steps of: providing a semiconductor substrate; forming a gate oxide layer over said substrate; forming a first polysilicon layer over said gate oxide layer; forming a mask layer over said first polysilicon layer; patterning said mask layer to define a floating gate region in said first polysilicon layer; implanting fluorine ions in said floating gate region in said first polysilicon layer; removing said layer; forming a sharp gate 6 bird's beak (GBB) in said floating gate region; etching said first polysilicon layer to form said floating gate; forming an oxide layer over said floating gate; forming a second polysilicon layer over said oxide layer; and patterning said second polysilicon layer to form a control gate.
Claim 3
Dependent Claim
11 words
The method of claim 1, wherein said semiconductor substrate is silicon.
Claim 4
Dependent Claim
19 words
The method of claim 1, wherein said gate oxide has a thickness between about 70 to 90 angstroms (Å).
Claim 5
Dependent Claim
19 words
The method of claim 1, wherein said first polysilicon layer has a thickness between about 1000 to 1200 Å.
Claim 6
Dependent Claim
22 words
The method of claim 1, wherein said mask layer is silicon nitride and has a thickness between about 700 to 800 Å.
Claim 7
Dependent Claim
26 words
The method of claim 5, wherein said patterning said mask layer is accomplished by using an etch recipe comprising gases SF 6 and O 2 .
Claim 8
Dependent Claim
34 words
The method of claim 1, wherein said implanting fluorine ions is accomplished at a dosage level between about 1×10 15 to 1×10 18 atoms/cm 2 and energy level between about 70 to 80 KEV.
Claim 9
Dependent Claim
39 words
The method of claim 1, wherein said forming a sharp bird's beak in said floating gate region is accomplished by wet oxidizing said first polysilicon layer having fluorine ions at a temperature between about 850° C. to 900° C.
Claim 10
Dependent Claim
28 words
The method of claim 1, wherein said etching said first polysilicon layer is accomplished with a recipe comprising gases HBr, Cl 2 , He and O 2 .
Claim 11
Dependent Claim
23 words
The method of claim 1, wherein said oxide layer over said first polysilicon layer has a thickness between about 200 to 300 Å.
Claim 12
Dependent Claim
24 words
The method of claim 1, wherein said second polysilicon layer has a thickness between about 2000 to 2500 Å to form said control gate.
Claim 13
Independent Claim
128 words
A method of forming sharp beak in a split-gate flash memory comprising the steps of: providing a semiconductor substrate; forming a gate oxide layer over said substrate; forming a first polysilicon layer over said gate oxide layer; forming a mask layer over said first polysilicon layer; patterning said mask layer to define a floating gate region in said first polysilicon layer; implanting oxygen ions in said floating gate region in said first polysilicon layer; removing said photoresist layer; forming a sharp gate bird's beak (GBB) in said floating gate region; etching said first polysilicon layer to form said floating gate; forming an oxide layer over said floating gate; forming a second polysilicon layer over said oxide layer; and patterning said second polysilicon layer to form a control gate.
Claim 14
Independent Claim
128 words
A method of forming sharp beak in a split-gate flash memory comprising the steps of: providing a semiconductor substrate; forming a gate oxide layer over said substrate; forming a first polysilicon layer over said gate oxide layer; forming a mask layer over said first polysilicon layer; patterning said mask layer to define a floating gate region in said first polysilicon layer; implanting oxygen ions in said floating gate region in said first polysilicon layer; removing said photoresist layer; forming a sharp gate bird's beak (GBB) in said floating gate region; etching said first polysilicon layer to form said floating gate; forming an oxide layer over said floating gate; forming a second polysilicon layer over said oxide layer; and patterning said second polysilicon layer to form a control gate.
Claim 15
Dependent Claim
11 words
The method of claim 12, wherein said semiconductor substrate is silicon.
Claim 16
Dependent Claim
19 words
The method of claim 12, wherein said gate oxide has a thickness between about 70 to 90 angstroms (Å).
Claim 17
Dependent Claim
19 words
The method of claim 12, wherein said first polysilicon layer has a thickness between about 1000 to 1200 Å.
Claim 18
Dependent Claim
22 words
The method of claim 12, wherein said mask layer is silicon nitride and has a thickness between about 700 to 800 Å.
Claim 19
Dependent Claim
26 words
The method of claim 16, wherein said patterning said mask layer is accomplished by using an etch recipe comprising gases SF 6 and O 2 .
Claim 20
Dependent Claim
34 words
The method of claim 12, wherein said implanting oxygen ions is accomplished at a dosage level between about 1×10 15 to 1×10 18 atoms/cm 2 and energy level between about 70 to 80 KEV.
Claim 21
Dependent Claim
39 words
The method of claim 12, wherein said forming a sharp bird's beak in said floating gate region is accomplished by wet oxidizing said first polysilicon layer having fluorine ions at a temperature between about 850° C. to 900° C.
Claim 22
Dependent Claim
28 words
The method of claim 12, wherein said etching said first polysilicon layer is accomplished with a recipe comprising gases HBr, Cl 2 , He and O 2 .
Claim 23
Dependent Claim
23 words
The method of claim 12, wherein said oxide layer over said first polysilicon layer has a thickness between about 200 to 300 Å.
Claim 24
Dependent Claim
24 words
The method of claim 12, wherein said second polysilicon layer has a thickness between about 2000 to 2500 Å to form said control gate.
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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) | 2003-07-25 | 2004-01-24 | 2004-07-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-07-25 | 2008-01-24 | 2008-07-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-07-25 | 2012-01-24 | 2012-07-25 | $7700.00 | Window Closed / Lapsed |