Influence of a direct current bias on the energy of ions from an electron cyclotron resonance plasma
The energy distributions of ions (IED) on the substrate in an electron cyclotron resonance discharge have been measured for methane at pressures of 5.4 x 1.0 E-2 and 1.1 x 1.0 E-1 Pa, for substrate holders with diameters ranging from 2.2 to 9.5 cm and dc-bias voltages between 0 and -120 V. The applied dc-bias is fully converted into an increase of ion energy only with the smallest substrate plate, and has no effect on the ion energy for the largest diameter. For intermediate diameters, the ion energy increases with increasing pressure at constant bias. This is explained by a model taking into account the sheath and anisotropic plasma resistivity. The current density does not increase with bias. From the observed small changes in full width at half-maximum and the percentage of low energy ions with increasing dc-bias voltage and sheath thickness it can be concluded that the sheath is collisionless.
Bibliographic Reference: Article: Journal of Vacuum Science and Technology A, Vol. 10 (1992) No. 3, pp. 434-438
Record Number: 199310024 / Last updated on: 1994-11-29
Original language: en
Available languages: en