Determining long minority carrier diffusion lengths
US5663657A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Sep 26, 1994 |
| Grant date | Sep 2, 1997 |
| Priority date | — |
| Expiry date | Sep 26, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L22/14
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Minority carrier diffusion lengths, especially long diffusion lengths that exceed the thickness of the wafer, are determined accurately and conveniently using techniques that limit errors due to lateral carrier diffusion, surface reflectivity, temperature variations, and inherent limitations in standard computation techniques that assume a diffusion length shorter than the wafer thickness. In particular embodiments, a probe is provided that senses the photovoltage in an area spaced from the edge of the illuminated region to provide a measurement substantially free of error from lateral carrier diffusion. The probe may also measure surface reflectivity simultaneously with measurement of photovoltage. Reflectivity correction is particularly beneficial in the analysis of wafers with dielectric coatings.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.