Strength and Fracture Resistance of Amorphous Diamond-Like Carbon Films for MEMS
Abstract
The mechanical strength and mixed mode I/II fracture toughness of hydrogen-free tetrahedral amorphous diamond-like carbon (ta-C) films, grown by pulsed laser deposition, are discussed in connection to material flaws and its microstructure. The failure properties of ta-C were obtained from films with thicknesses 0.5–3 μm and specimen widths 10–20 μm. The smallest test samples with 10 μm gage section averaged a strength of 7.3±1.2 GPa, while the strength of 20-μm specimens with thicknesses 0.5–3 μm varied between 2.2–5.7 GPa. The scaling of the mechanical strength with specimen thickness and dimensions was owed to deposition-induced surface flaws, and, only in the smallest specimens, RIE patterning generated specimen sidewall flaws. The mode I fracture toughness of ta-C films isKIc=4.4±0.4 MPam, while the results from mixed mode I/II fracture experiments with cracks arbitrarily oriented in the plane of the film compared very well with theoretical predictions.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jan 01, 2009
- Source ID
- 10.1155/2009/204281
Entities
People
- I. Chasiotis
- K. N. Jonnalagadda
Organizations
- Air Force Office of Scientific Research
- Johns Hopkins University
- University of Illinois Urbana–Champaign