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US 4,807,994 AGranted
Method of mapping ion implant dose uniformity
AssigneeVarian Associates, Inc.
InventorsSusan B. Felch, Ronald A. Powell
Life of this patent
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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.
Claims6
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.
3 more elements
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.
3 more elements
Dependencies are inferred from the claim text.