Plasma process uniformity across a wafer by apportioning ground return path impedances among plural VHF sources
US7884025B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 11, 2007 |
| Grant date | Feb 8, 2011 |
| Priority date | — |
| Expiry date | Aug 28, 2029 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/6831
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
In a plasma reactor chamber a ceiling electrode and a workpiece support electrode, respective RF power sources of respective VHF frequencies f1 and f2 are coupled to either respective ones of the electrodes or to a common one of the electrodes, where f1 is sufficiently high to produce a center-high non-uniform plasma ion distribution and f2 is sufficiently low to produce a center-low non-uniform plasma ion distribution. Respective center ground return paths are provided for RF current passing directly between the ceiling electrode and the workpiece support electrode for the frequencies f1 and f2, and an edge ground return path is provided for each of the frequencies f1 and f2. The impedance of at least one of the ground return paths is adjusted so as to control the uniformity of the plasma ion density distribution.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.