Accurate measuring of long steady state minority carrier diffusion lengths
US8093920B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 21, 2009 |
| Grant date | Jan 10, 2012 |
| Priority date | — |
| Expiry date | Jul 13, 2030 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L22/14
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
Surface photo-voltage measurements are used to accurately determine very long steady state diffusion length of minority carriers and to determine iron contaminant concentrations and other recombination centers in very pure wafers. Disclosed methods use multiple (e.g., at least two) non-steady state surface photovoltage measurements of diffusion length done at multiple (e.g., at least two) modulation frequencies. The measured diffusion lengths are then used to obtain a steady state diffusion length with an algorithm extrapolating diffusion length to zero frequency. The iron contaminant concentration is obtained from near steady state measurement of diffusion length at elevated frequency before and after iron activation. The concentration of other recombination centers can then be determined from the steady state diffusion length and the iron concentration measured at elevated frequency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.