Micro photoreflectance semiconductor wafer analyzer
US5365334A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 21, 1990 |
| Grant date | Nov 15, 1994 |
| Priority date | — |
| Expiry date | Dec 21, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L22/14
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus for measuring local carrier concentration in a preselected area of a semi-conductor is shown and described. An exciting light (preferably a laser) alters the sample's band-gap by photo injecting electron hole pairs in the area being measured. Because of the Franz-Keldysh effect, the photo injected carriers alter the sample's reflectivity. An optical fiber conducts a broad band source of probing light to the excited area on the sample. The sample reflects some of the broad band light back into a fiber that conducts the reflected light to an optical analyzer. The optical analyzer includes a dispersive element that disperses the reflected light onto a linear array of detectors. The analyzer thus simultaneously samples multiple wavelengths in the reflected spectrum. From the resulting samples, a computer deconvolutes the spectral line shape into a measurement of the local electric field and the local carrier concentration.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.