Radiometric measurement of wafer temperatures during deposition
US4823291A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 10, 1987 |
| Grant date | Apr 18, 1989 |
| Priority date | — |
| Expiry date | Sep 10, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01J5/58
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
An infrared heat source is directed through a chopper or modulator and beam splitter to the surface of the water. A pair of radiometers are provided, one located behind the back surface of the wafer to measure transmittance, the other adjacent to the beam splitter to measure wafer reflectance. The wafer temperature may then be calculated using an experimentally determined relationship between wafer radiance W.sub.W and wafer temperature, with wafer radiance being provided by the relationship ##EQU1## where r.sub.BS is the reflectance of the beam splitter, W.sub.W is the blackbody radiance of the wafer, W.sub.a is the blackbody radiance equivalent to ambient temperature, and e.sub.W is the wafer emittance. Alternatively, rather than locate a radiometer behind the wafer to measure wafer transmittance, a mirror may be located behind the wafer to reflect the transmitted energy back through the wafer on a periodic basis for a short part of each duty cycle. A single radiometer can then measure both the reflected and transmitted energy.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.