| AVS 60th International Symposium and Exhibition | |
| Plasma Science and Technology | Monday Sessions |
| Session PS+TF-MoA |
| Session: | Plasma Deposition |
| Presenter: | E.V. Johnson, LPICM-CNRS, Ecole Polytechnique, France |
| Authors: | E.V. Johnson, LPICM-CNRS, Ecole Polytechnique, France B. Bruneau, LPICM-CNRS, Ecole Polytechnique, France P.A. Delattre, LPP-CNRS, Ecole Polytechnique, France T. Lafleur, LPP-CNRS, Ecole Polytechnique, France J.-P. Booth, LPP-CNRS, Ecole Polytechnique, France |
| Correspondent: | Click to Email |
The use of Tailored Voltage Waveforms (TVWs) to manipulate the Electrical Asymmetry Effect in a capacitively coupled plasma-enhanced chemical vapour deposition (CCPECVD) chamber has been shown to be an effective technique for device quality thin-film deposition [1,2], and a useful tool to study the interaction of the bulk and sheath properties of processing plasmas [3] and their impact on growth surfaces [4].
We have used this technique to directly study the influence of mean ion-bombardment energy (IBE) on the growth of hydrogenated microcrystalline silicon (μc-Si:H) in a CCP chamber, with otherwise unchanged plasma conditions. In this work, we discuss recent results on a specific aspect of μc-Si:H growth for photovoltaic applications, the amorphous to μc phase transition. The dependence of this transition on many other parameters (power, pressure, dilution) makes the direct observation of the effect of IBE very difficult, as recently demonstrated by the efforts of other authors [5]. We instead use TVWs to vary the IBE, and in-situ ellipsometry to observe the transition in real time for a number of deposition chemistries, such as H2/SIH4 and Ar/H2/SiF4. Furthermore, in addition to maximizing or minimizing the IBE by changing the waveform shape, the sheath expansion/contraction rates at the powered electrode can equally be controlled. The unexpected impact of these conditions for the μc-Si:H nucleation rate are presented, underlining the importance of "Tailoring" the waveform to the specific plasma processing goal.
Finally, we address an outstanding issue that has challenged the use of TVW's in an industrial setting – the difficulty of matching a TVW source to a CCP chamber. This has previously limited their use to only two harmonics for exciting a large area reactor at high power. We present experimental results for a prototype, high-power multifrequency matchbox that allows the effective coupling of the full output power of the amplifier to the PECVD chamber, enabling high deposition rate μc-Si:H. These increased deposition rates, along with in-situ observation of the film evolution during growth, will be shown.
[1] E.V. Johnson, P-A. Delattre, and J.P. Booth, Appl. Phys. Lett. 100 (2012) 133504.
[2] D. Hrunski, et al, Vacuum 87 (2013) 114.
[3] T. Lafleur, P.A. Delattre, E.V. Johnson, and J.P. Booth. Appl. Phys. Lett.101, (2012)124104.
[4] E.V. Johnson, S. Pouliquen, P-A. Delattre, and J.P. Booth, J. Non-Cryst. Solids 358. (2012), 1974.
[5]A. C. Bronneberg, N. Cankoy, M. C. M. van de Sanden, and M. Creatore, J. Vac. Sci. Technol. A30, 061512 (2012).