ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
A variety of effects of substrate bias upon an electron cyclotron resonance plasma deposition have been studied, taking the deposition of amorphous boron carbide films as an example. First, the impact energy of ions incident on substrates was studied through the variation of the sheath potentials formed on insulating and conducting substrates. For this purpose, the plasma potential (Vp) was measured by the bias current-voltage (Ib-Vb) analysis, and the floating potential (Vf) was measured by the Langmuir probe method. These analyses show that the plasma potential is sufficiently influenced by the substrate bias for positive biases even if the area of the bias electrode is small. The energy of ions incident on conducting substrates is not effectively changed by imposing a positive bias. This effect can be explained in terms of the global balance of the electron and ion currents. This consideration leads to the criterion for the area of bias electrode at which the substrate bias perturbs the plasma potential. Next, the effects of the substrate bias upon the deposition processes and properties of the deposited films were studied through the variations of the deposition rates and the infrared absorption due to the atomic vibrations in the films. The deposition rates vary with the substrate bias according to the variation of sheath potentials: Vp−Vf for insulating substrates and Vp−Vb for conducting substrates. As the substrate bias increases negatively, the deposition rate on conducting substrates increases. This increase is hardly explained by the direct contribution of ions to the deposition. The comparison with other relevant discharge phenomena leads to the importance of the secondary electrons emitted from the substrate surface caused by the ion bombardment. The secondary electrons increase the densities of condensable neutral radicals in the vicinity of the substrate in a way similar to dc discharges.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.346217
