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US4807994A
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Method of mapping ion implant dose uniformity
Assignee: Varian Medical Systems Inc
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Filing: 1987-11-19
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Granted: 1989-02-28
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Expires: 2007-11-19
Abstract
Abstract A method of mapping implanted ion dose uniformity is disclosed in which wafers of polysilicon-on-silicon or polysilicon-on-oxidized-silicon are implanted with the ion dose to be mapped and then scanned in a spectrophotmeter using monochromatic radiation. An interference spectral technique is used to achieve improved sensitivity while preserving thermal and electrical properties close to those of actual devices.
Inventors
- 👤 Susan B. Felch
- 👤 Ronald A. Powell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 22:35
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/84; G01N21/8422; G01N21/17; G01N2021/178; G01N21/25; G01N21/31; G01N21/35; G01N21/3563; G01N2021/3568; G01N21/41; G01N21/45; G01N21/59
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
136 words
A method of mapping ion dose uniformity, comprising the steps: (a) scanning wafers having a thin film or polysilicon coated on a substrate made of optically transparent material while measuring the optical transmission spectrum, thereby calibrating wafers suitable for subsequent steps, (b) inserting in the ion implantation device to be mapped a wafer calibrated in step (a), (c) implanting an ion dose in said thin layer of polysilicon in a controlled pattern, (d) removing said wafer from said ion implantation device, (e) scanning the wafer while measuring the optical transmission spectrum of the implanted film using essentially monochromatic radiation and a detection bandwidth of not more than 1 nm, and (f) calculating the dose distribution from the data of the optical transmission spectrum data, film thickness calibration data and calibration data from known ion implant doses.
Claim 2
Independent Claim
136 words
A method of mapping ion dose uniformity, comprising the steps: (a) scanning wafers having a thin film or polysilicon coated on a substrate made of optically transparent material while measuring the optical transmission spectrum, thereby calibrating wafers suitable for subsequent steps, (b) inserting in the ion implantation device to be mapped a wafer calibrated in step (a), (c) implanting an ion dose in said thin layer of polysilicon in a controlled pattern, (d) removing said wafer from said ion implantation device, (e) scanning the wafer while measuring the optical transmission spectrum of the implanted film using essentially monochromatic radiation and a detection bandwidth of not more than 1 nm, and (f) calculating the dose distribution from the data of the optical transmission spectrum data, film thickness calibration data and calibration data from known ion implant doses.
Claim 3
Dependent Claim
11 words
The method of claim 1 in which the substrate comprises quartz.
Claim 4
Dependent Claim
35 words
The method of claim 1 where step (e) is performed at a wavelength selected at a midpoint between a minimum and a maximum in the interference transmission spectrum of the wafer measured before ion implantation.
Claim 5
Independent Claim
130 words
A method of mapping ion dose uniformity, comprising the steps: (a) scanning wafers having a thin film of polysilicon coated on a substrate while measuring the optical reflection spectrum, thereby calibrating wafers suitable for subsequent steps, (b) inserting in the ion implantation device to be mapped a wafer calibrated in step (a), (c) implanting an ion dose in said thin layer of polysilicon in a controlled pattern, (d) removing said wafer from said ion implantation device, (e) scanning the wafer while measuring the optical reflection spectrum of the implanted film using essentially monochromatic radiation and a detection bandwidth of not more than 1 nm, and (f) calculating dose distribution from the data of the optical reflection spectrum data, film thickness calibration data, and calibration data from known ion implant doses.
Claim 6
Independent Claim
130 words
A method of mapping ion dose uniformity, comprising the steps: (a) scanning wafers having a thin film of polysilicon coated on a substrate while measuring the optical reflection spectrum, thereby calibrating wafers suitable for subsequent steps, (b) inserting in the ion implantation device to be mapped a wafer calibrated in step (a), (c) implanting an ion dose in said thin layer of polysilicon in a controlled pattern, (d) removing said wafer from said ion implantation device, (e) scanning the wafer while measuring the optical reflection spectrum of the implanted film using essentially monochromatic radiation and a detection bandwidth of not more than 1 nm, and (f) calculating dose distribution from the data of the optical reflection spectrum data, film thickness calibration data, and calibration data from known ion implant doses.
Claim 7
Dependent Claim
22 words
The method of claim 4 in which the substrate comprises a wafer of silicon coated with a thin layer of silicon dioxide.
Claim 8
Dependent Claim
35 words
The method of claim 4 wherein step (e) is performed at a wavelength selected at a midpoint between a minimum and a maximum in the interference reflection spectrum of the wafer measured before ion implantation.
References Cited (Backward Citations)
US4676647A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1992-02-28 | 1992-08-29 | 1993-02-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-28 | 1996-08-29 | 1997-02-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-28 | 2000-08-29 | 2001-02-28 | $7700.00 | Window Closed / Lapsed |