Electron density measurement and plasma process control system using a microwave oscillator locked to an open resonator containing the plasma
US6741944B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | May 22, 2002 |
| Grant date | May 25, 2004 |
| Priority date | — |
| Expiry date | May 22, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J37/3299
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A system for measuring plasma electon densities (e.g., in the range of 1010 to 1012 cm−3) and for controlling a plasma generator (240). Measurement of the plasma density is essential if plasma-assisted processes, such depositions or etches, are to be adequately controlled using a feedback control. Both the plasma measurement method and system generate a control voltage that in turn controls the plasma generator (240) to maintain the plasma electron density at a pre-selected value. The system utilizes a frequency stabilization system to lock the frequency of a local oscillator (100) to the resonant frequency of an open microwave resonator (245) when the resonant frequency changes due to the introduction of a plasma within the open resonator. The amplified output voltage of a second microwave discriminator may be used to control a plasma generator (240).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.