Determination of ionization fraction and plasma potential in a dc magnetron sputtering system using a quartz crystal microbalance and a gridded energy analyzer
A diagnostic which combines a quartz crystal microbalance and a gridded energy analyzer has been developed to measure the ion-to- neutral ratio and the plasma potential in a commercial dc magnetron sputtering device. Additional features of this sensor include an externally controlled shutter which protects the diagnostic when it is in the chamber, but it is not in use. The diagnostic is mounted on a linear motion feedthrough and embedded in a slot in the wafer chuck to allow for measuring uniformity in deposition and ionization throughout the plane of the wafer. RF power is introduced to ionize the Al particles. Using the quartz crystal microbalance and the gridded energy analyzer, the ion-to-neutral ratio and other parameters are determined. Comparing the total deposition rate with and without a bias that screens out the ions, but leaves the plasma undisturbed, allows for the determination of the ion-to-neutral ratio. By varying the voltage applied to the grids, the plasma potential is measured. For example, a magnetron configuration having a pressure of 35 mtorr, a dc power of 2 kW, and a net rf power of 310{+-}5 W yielded 78{+-}5% ionization and a plasma potential of 35{+-}1 V.
- Research Organization:
- Oak Ridge Inst. for Science and Education, TN (United States); Univ. of Illinois at Urbana-Champaign, IL (United States)
- Sponsoring Organization:
- USDOE Assistant Secretary for Nuclear Energy, Washington, DC (United States)
- DOE Contract Number:
- AC05-76OR00033
- OSTI ID:
- 531049
- Report Number(s):
- DOE/OR/00033-T700; ON: DE97053350
- Resource Relation:
- Other Information: PBD: Jan 1997
- Country of Publication:
- United States
- Language:
- English
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