Optical illumination and inspection system for wafer and solar cell defects
US5334844A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 5, 1993 |
| Grant date | Aug 2, 1994 |
| Priority date | — |
| Expiry date | Apr 5, 2013 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S136/29
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical inspection system for detecting cracks in a crystalline substrate. The crystalline substrate that is to be inspected is located in a test plane in the field of view of a video camera. A first collimated light source projects light which is passed through a long pass filter. The filtered collimated light is projected onto the reflective surface of a panel that contains surface irregularities in the same order as the wavelength of the filtered, collimated light. The light is diffused by the panel surface and reflected onto the crystalline substrate at a plurality of various angles. The light passes through the crystalline substrate and is reflected into the path of the field of view of the video camera and forms an object image from which a real image is created and may be viewed on a control monitor. Cracks in the solar cell silicon layer or glass covers can be observed on the control monitor, and printed by a video graphics printer or stored via a VCR for permanent documentation purposes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.