Methods of inspecting wafers for manufacturing light emitting elements
US5440384A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 30, 1993 |
| Grant date | Aug 8, 1995 |
| Priority date | — |
| Expiry date | Aug 30, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10H20/824
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An irradiation light containing a light which wave length is not absorbed by the n-type clad layer, but is absorbed by the p-type active layer, is applied on the wafer for manufacturing light emitting elements with a double-hetero structure of a p-type clad layer, a p-type active layer and an n-type clad layer formed one after another on a semiconductor substrate. Defects are found by detecting the increased photoluminescent light due to generation of a conductivity-type inverted layer such as the n-type inverted layer. When the double-hetero structure is composed of a GaAlAs mixed crystal compound semiconductor, the irradiation light which contains a wavelength range of 600-650 nm is applied. When the defective area is an active layer deficient area, detection is conducted by using the reflection light from the surface of the semiconductor substrate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.