Method utilizing a modulated light beam for determining characteristics such as the doping concentration profile of a specimen of semiconductor material
US6034535A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 12, 1997 |
| Grant date | Mar 7, 2000 |
| Priority date | — |
| Expiry date | Jun 12, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N33/0095
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for determining the doping concentration profile of a specimen of semiconductor material. The specimen is positioned between a pair of electrodes, the specimen being disposed on one of the electrodes and being spaced from the other electrode by an air gap. A signal is provided corresponding to the total capacitance between the two electrodes. A region of the surface of the specimen is illuminated with a beam of light of wavelengths shorter than that corresponding to the energy gap of the semiconductor material and which is intensity modulated at a predetermined frequency. A variable DC bias voltage is applied between the pair of electrodes, the variable bias voltage varying between that corresponding to accumulation and that corresponding to deep depletion for the specimen. The intensity of the light beam is low enough and the speed at which the DC bias voltage is varied is fast enough such that no inversion layer is formed at the surface of the specimen. A signal is provided representing the ac photocurrent induced at the region of the specimen illuminated by the light beam. The intensity of the light beam and frequency of modulation of the light beam are selected such th…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.