Thin film thickness measuring method
US4899055A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 12, 1988 |
| Grant date | Feb 6, 1990 |
| Priority date | — |
| Expiry date | May 12, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/0633
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method of measuring thin film thickness, especially on semiconductor substrates, in which the substrate is illuminated with ultraviolet light of a fixed wavelength corresponding to a persistent spectral line and the amount of light reflected from the substrate is detected and measured. The ultraviolet light preferably has a wavelength in the range from 240 nm to 300 nm, and the 253.6 nm spectral line of mercury is considered best. Comparing the measured amount of light from the substrate to a known amount of light detected from a standard calibration substrate with known reflectivity, the reflectivity of the test substrate is computed. The thickness of a thin film on the substrate is determined from the computed reflectivity using Fresnel's equation or a lookup table derived from the same.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.