Self-calibration in non-contact surface photovoltage measurement of depletion capacitance and dopant concentration
AssigneeSemiconductor Diagnostics, Inc.
InventorDmitriy Marinskiy
Life of this patent
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Abstract
The surface photovoltage dopant concentration measurement of a semiconductor wafer is calibrated by biasing the semiconductor wafer into an avalanche breakdown condition in a surface depletion region; determining a contact potential difference value corresponding to an avalanche breakdown; determining small signal ac-surface photovoltage value corresponding to an avalanche breakdown; and using the values of the contact potential and the surface photovoltage to calculate a calibration constant that relates depletion layer capacitance and an inverse of the surface photovoltage.
Claims20
A method for calibrating the surface photovoltage dopant concentration measurement of a semiconductor wafer, the method comprising:
- biasing the semiconductor wafer into an avalanche breakdown condition in a surface depletion region;
- determining a contact potential difference value corresponding to an avalanche breakdown;
- determining small signal ac-surface photovoltage value corresponding to an avalanche breakdown;
- and
- using the values of the contact potential and the surface photovoltage to calculate a calibration constant that relates depletion layer capacitance and an inverse of the surface photovoltage.
A system for calibrating a surface photovoltage dopant concentration measurement of a semiconductor wafer, the system comprising:
- a corona electrode configured to bias the semiconductor wafer into an avalanche breakdown condition in a surface depletion region;
- a first probe configured to determine a contact potential difference value corresponding to an avalanche breakdown;
- a second probe configured to determining small signal ac-surface photovoltage value corresponding to an avalanche breakdown;
- and
- a processor configured to use the values of the contact potential and the surface photovoltage to calculate a calibration constant that relates depletion layer capacitance and an inverse of the surface photovoltage.
A computer program product tangibly embodied in an information carrier, the computer program product comprising instructions to cause a machine to:
- determine a contact potential difference value corresponding to an avalanche breakdown;
- determine small signal ac-surface photovoltage value corresponding to an avalanche breakdown,
- use the values of the contact potential and the surface photovoltage to calculate a calibration constant that relates depletion layer capacitance and an inverse of the surface photovoltage.
Dependencies are inferred from the claim text.