Effects of Ion Bombardment Energy Flux on Chemical Compositions and Structures of Hydrogenated Amorphous Carbon Films Grown by a Radical-Injection Plasma-Enhanced Chemical Vapor Deposition

Abstract

Hydrogenated amorphous carbon (a-C:H) films have attracted much attention, because of their excellent physical and chemical properties, such as high mechanical hardness, chemical robustness, a wide variety of optical bandgaps, and so forth. Although an ion bombardment energy has been regarded as essential in the well-know subplantation model, it alone is inadequate especially in complicated reactions of a plasma-enhanced chemical vapor deposition process. In this study, an ion bombardment energy flux (ΓEi) was proposed as a crucial factor to determine chemical compositions and structures of a-C:H films. To obtain the amounts of ΓEi, electron densities, hydrogen (H) excitation temperatures, and negative direct current (DC) self-bias voltage (-VDC) were measured. The deposition rate increased, and sp2-C clusters incorporation was induced by the ΓEi. With increasing ΓEi, photoluminescence (PL) backgrounds in Raman spectra decreased, while spin densities in electron spin resonance (ESR) measurements increased. These results suggested the H content of a-C:H film decreased depending on the amount of ΓEi. The ΓEi is one of the crucial factors to determine the properties of the a-C:H films.

Deposition of hydrogenated amorphous carbon films by CH4/Ar capacitively coupled plasma using tailored voltage waveform discharges

“…H. Sugiura et al used a dual frequency discharge setup consisting of 100 MHz very HF (VHF) at the upper electrode and 13.56 MHz RF at the lower electrode to deposit a-C:H films. 60) The power of the VHF at the upper electrode was set at either 20 W or 250 W to control radical generation constantly. The RF power at the lower electrode ranged from 30 W to 150 W to control V DC , which is related to the IBE.…”

“…Fig.9. Comparisons between this study [TVWs (13.56 + 27.12 MHz, V PP 360 and 480 V, phase shift 0°∼ 90°), single frequency (13.56 MHz, V PP 287 -647V)] and previous ones (single frequency (13.56 MHz),59) VHF (20 W and 250 W) with RF bias60) ) regarding the relationship between the deposition rate of a-C:H film and V DC . Figure9(a) is a figure enlarged of the area enclosed by the dashed line in Fig.9(b).…”