Fracture of atomic layer deposited tungsten films

N. R. Moody, J. M. Jungk, T. M. Mayer, R. A. Wind, S. M. George, W. W. Gerberich

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

Atomic layer deposited (ALD) films are an ideal choice for enhancing the performance and reliability of microsystem devices. The self-limiting chemistry results in conformal coatings of high aspect ratio structures with monolayer precision. ALD tungsten films are of particular interest for MEMS and LIGA applications due to their good wear resistance. However, property data is extremely limited as most conventional test methods are difficult to apply to these very thin films. We therefore began a study of ALD tungsten films on silicon substrate properties as a function of film thickness using nanoindentation and nanoscratch techniques. Nanoindentation showed that elastic modulus and hardness increased with film thickness. For the thickest films, these values were substantially higher than those of the substrate and hardness equaled values for bulk and sputter deposited films. Of particular concern, nanoscratch tests triggered channel cracking and delamination in the thickest film. These cracks formed in succession during the scratch tests closely following the path established by the previous cracks. Mechanics-based cracking and delamination models showed that the films fractured under steady state conditions at an energy of 0.4 J/m2. The corresponding interfacial fracture energy for film delamination between the channel cracks was substantially less at 50 mJ/m2 with a mode I component equal to 30 mJ/m2. This value is less than the work of adhesion for sputter deposited tungsten films on silicon substrates but may accurately reflect the influence of lower film density along the substrate interface.

Original languageEnglish (US)
Title of host publication11th International Conference on Fracture 2005, ICF11
Pages2135-2140
Number of pages6
StatePublished - Dec 1 2005
Event11th International Conference on Fracture 2005, ICF11 - Turin, Italy
Duration: Mar 20 2005Mar 25 2005

Publication series

Name11th International Conference on Fracture 2005, ICF11
Volume3

Other

Other11th International Conference on Fracture 2005, ICF11
CountryItaly
CityTurin
Period3/20/053/25/05

Fingerprint Dive into the research topics of 'Fracture of atomic layer deposited tungsten films'. Together they form a unique fingerprint.

  • Cite this

    Moody, N. R., Jungk, J. M., Mayer, T. M., Wind, R. A., George, S. M., & Gerberich, W. W. (2005). Fracture of atomic layer deposited tungsten films. In 11th International Conference on Fracture 2005, ICF11 (pp. 2135-2140). (11th International Conference on Fracture 2005, ICF11; Vol. 3).