Method and apparatus for releasing a workpiece from and electrostatic chuck
US5790365A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 31, 1996 |
| Grant date | Aug 4, 1998 |
| Priority date | — |
| Expiry date | Jul 31, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T279/23
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
An apparatus and concomitant method that applies an oscillating voltage to at least one electrode of an electrostatic chuck. The apparatus is a switching circuit connected between the electrostatic chuck power supply and an electrode or electrodes of an electrostatic chuck. In one contact position, the relay applies the electrostatic chuck chucking voltage to the electrode(s). While in a second contact position, the electrode(s) is connected through an inductor to a predetermined potential, e.g., ground. To dechuck a wafer from the chuck surface, the relay is switched from the first position to the second position connecting the electrode(s) through the inductor to ground. Because the wafer and the chuck electrode(s) form a parallel plate capacitor, this inductor and capacitor combination forms a tank circuit that oscillates at a resonant frequency. As such, energy is transferred between the capacitor and the inductor, and vice versa, in a decaying manner over a period of time that is defined by the Q of the tank circuit. This oscillating energy produces an oscillating voltage across the wafer-to-chuck interface that discharges any residual charge between the wafer and chuck.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.