Method and apparatus for imaging semiconductor devices
US6316950A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 15, 1997 |
| Grant date | Nov 13, 2001 |
| Priority date | — |
| Expiry date | May 15, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R31/311
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Semiconductor devices are imaged using two-photon absorption. The method is similar to conventional optical beam induced imaging except that the light beams used have frequencies (photon energies) insufficient to excite electrons across the semiconductor bandgap. Rather the instantaneous intensity of the lower frequency light is increased, as by using a pulsed laser source, so that electron transitions occur by two-photon absorption predominately in the localized region where the beam is focused. The result is minimal absorption during passage through the substrate and maximal absorption in the component-rich active layer where the beam is focused. This enhances imaging of fine-detail semiconductor devices. Specifically, the quadratic dependence of free carrier generation on the excitation intensity both enhances the resolution and provides a three-dimensional sectioning capability.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.