Platen for electrostatic wafer clamping apparatus
US6660665B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | May 1, 2002 |
| Grant date | Dec 9, 2003 |
| Priority date | — |
| Expiry date | May 13, 2022 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/24917
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A platen for electrostatic wafer clamping apparatus comprising a platen body of dielectric material and grains of electrically conductive material diffused in the dielectric material so that the platen has a relatively large electrostatic capacitance due to the diffusion of the conductive grains with the result that the platen provides an increased clamping force regardless of humidity. In accordance with another aspect of the invention, the thickness of the platen body can be decreased by an amount sufficient to maintain a constant clamping force with reduced applied voltage, to eliminate any residual voltage on the platen and to increase the speed of wafer release. The grains of electrically conductive material are present in an amount of from about 2.5 percent to about 15.0 percent of the volume of the platen body, and the grains of electrically conductive material are selected from the group consisting of carbonated transition metals, nitrified transition metals and carbonated grains. The dielectric material preferably is Al2O3, and the grains of electrically conductive material preferably are TiC and preferably in an amount of about 5% of the volume of the platen.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.