Method of measuring gas purity information, chamber unit and exposure unit using the method and a device production method
US5467637A · kind A · utility
15Cited by
10References
26Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Dec 17, 1993 |
| Grant date | Nov 21, 1995 |
| Priority date | — |
| Expiry date | Dec 17, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/102
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The sonic velocity in a chamber which is filled with helium is measured by using ultrasonic waves, and the temperature in the chamber is also measured. Purity information relating to helium gas contained in the chamber is determined on the basis of the measured values of the sonic velocity and the temperature.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.