Nanoscratch testing of a-SiC:H films on silicon wafers deposited by PECVD

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Adhesion of thin film to the substrate is one of the most important properties in determining its application possibilities. Thin films of hydrogenated amorphous carbon-silicon (a-SiC:H) alloy were deposited on silicon wafers from tetravinylsilane (TVS) monomer by plasma-enhanced chemical vapor deposition (PECVD). The silicon wafers were pretreated with argon or oxygen plasmas (10 sccm, 5.7 Pa, 5-200 W) using continuous wave for 10 min to clean the surface from adsorbed gases and reach reproducible adhesion of films. A mass flow rate of TVS used for film deposition was 3.8 sccm at a pressure of 2.7 Pa. Pulsed plasma was employed to deposit thin films at an effective power ranging from 2 to 150 W. Thin films of 0.1 μm thickness were tested by scratch test using a conical (90 °) diamond tip with a radius of 1 µm, linearly loading with time from 1 µN to 6 mN at a loading rate of 12 mN/min and using a scratch length of 10 μm. The film adhesion was characterized by the critical load that is defined as the load at which the adhesive failure occurs in the scratch track observed by atomic force microscopy. We revealed that the critical load for a-SiC:H films increased with enhanced power from 1.6 mN (2 W) up to 4.6 mN (75 W) and was invariable for higher power 4.4 mN (150 W). Different powers (5-200 W) applied for wafer pretreatment with argon or oxygen plasmas did not affect the film adhesion. No aging effects were observed in the first 850 days after film deposition.

PECVD, thin films, adhesion, nanoscratch test

PLICHTA, T.; BRÁNECKÝ, M.; ČECH, V.

12. 4. 2017

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