Method for contactless testing of conducting paths in a substrate using photon-assisted tunneling
US4999577A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 15, 1989 |
| Grant date | Mar 12, 1991 |
| Priority date | — |
| Expiry date | Jun 15, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R31/308
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
For testing the integrity of conducting lines on or in a substrate, the following steps are executed: (I) Selected pads are irradiated by a focused optical beam so that they are positively charged due to photon-assisted tunneling of electrons from those pads. The charges propagate through existing conductors so that all selected pads and all pads connected to them assume a specific voltage. (II) The whole surface is irradiated by a flooding optical beam. Photon-assisted tunneling of electrons will now occur from those pads which were not charged previously. (III) The tunneling electrons excite an electroluminescent layer whose illumination reveals the spatial distribution of uncharged pads. This method is performed in air under atmospheric conditions and allows completely contactless testing of circuitry to detect line interruptions as well as shortcuts between separate lines. It is suited for surface lines, buried lines and for via connections.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.