End point detection method for plasma etching of semiconductor wafers with low exposed area
US7871830B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 18, 2006 |
| Grant date | Jan 18, 2011 |
| Priority date | — |
| Expiry date | Dec 14, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L22/26
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method for controlling the plasma etching of semiconductor wafers determines the impedance of a plasma chamber using values representing voltage, current, and the phase angle between them, as provided by a sensor. All or less than all of the data during a first time period may be used to calculate a model. During a second time period, real time data is used to calculate a version of the instant impedance of the chamber. This version of impendence is compared to a time-projected version of the model. The method determines that etching should be stopped when the received data deviates from the extrapolated model by a certain amount. In some embodiments a rolling average is used in the second time period, the rolling average compared to the model to determine the end point condition.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.