Method and apparatus for verifying the presence of a material applied to a substrate
US5841543A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 9, 1995 |
| Grant date | Nov 24, 1998 |
| Priority date | — |
| Expiry date | Mar 9, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/956
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The invention provides a process for evaluating a substrate, such as a wafer of semiconductive material having a semiconductor die at least partially formed thereon, as to the condition of an overlying film, such as an overlying film of photoresist that is applied to the semiconductor die prior to metal etching and ion implantation. The condition of the film is evaluated by exposing at least a portion of the substrate to electromagnetic radiation and evaluating the wave profile of the reflected beam. In instances where it is desirable to evaluate the substrate for the presence or absence of photoresist, ultraviolet or near ultraviolet light having a wavelength of about 240-650 nm can be used, as such wavelengths are strongly absorbed by photoresist. In contrast, areas of the substrate that are not covered by photoresist will not significantly absorb ultraviolet or near ultraviolet radiation. The presence or absence of the film under study can be evaluated by detecting reflected light from the substrate and comparing the detected light to a known profile. When photoresist films are under evaluation, the profile will feature portions of relatively low amplitude, which correspond to a…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.