Frequency monitoring to detect plasma process abnormality
US8174400B2 · kind B2 · utility
307Cited by
1References
15Claims
0Family size
Assignee
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Key dates
| Filing date | Mar 7, 2011 |
| Grant date | May 8, 2012 |
| Priority date | — |
| Expiry date | Mar 7, 2031 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H7/40
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Abnormal conditions within an RF-powered plasma process chamber are detected by detecting whether the frequency of a variable-frequency RF power supply moves outside established lower and upper limits. In a first aspect, a first pair of lower and upper limits are established as a function of the frequency of the power supply sampled after a new process step begins or after a sample control signal changes state. In a second aspect, a second pair of lower and upper limits are not adapted to the frequency of the power supply. Both aspects preferably are used together to detect different occurrences of abnormal conditions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.