Title: Nanomechanical study of amorphous and polycrystalline ALD HfO2 thin films

Authors: K. Tapily, J.E. Jakes, D. Gu, H. Baumgart, A.A. Elmustafa

Addresses: Department of Electrical Engineering, Old Dominion University, Norfolk, Virginia 23529, USA; Applied Research Center, Newport News, Virginia, 23606, USA. ' Performance Enhanced Biopolymers, USDA Forest Products Laboratory, Madison, Wisconsin, 53726, USA; Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA. ' Department of Electrical Engineering, Old Dominion University, Norfolk, Virginia 23529, USA; Applied Research Center, Newport News, Virginia, 23606, USA. ' Department of Electrical Engineering, Old Dominion University, Norfolk, Virginia 23529, USA; Applied Research Center, Newport News, Virginia, 23606, USA. ' Applied Research Center, Newport News, Virginia, 23606, USA; Department of Mechanical Engineering, Old Dominion University, Norfolk, Virginia 23529, USA

Abstract: Thin films of hafnium oxide (HfO2) were deposited by atomic layer deposition (ALD). The structural properties of the deposited films were characterised by transmission electron microscopy (TEM) and X-ray diffraction (XRD). We investigated the effect of phase transformations induced by thermal treatments on the mechanical properties of ALD HfO2 using nanoindentation. The elastic modulus of the amorphous low temperature deposited ALD HfO2 films was measured to be 370 ± 20 GPa. Subsequent to crystallisation by annealing in a rapid thermal annealing (RTA) chamber, the elastic modulus dropped to 240 ± 20 GPa. Similarly, the Meyer hardness decreased from a value of 18 ± 1 GPa for amorphous HfO2 to 15 ± 1 GPa following the transition temperature from amorphous to polycrystalline HfO2.

Keywords: atomic layer deposition; ALD; nanoindentation; high-k dielectrics; elastic modulus; hardness; hafnium oxide; HfO2 thin films; phase transformations.

DOI: 10.1504/IJSURFSE.2011.041402

International Journal of Surface Science and Engineering, 2011 Vol.5 No.2/3, pp.193 - 204

Available online: 21 Jul 2011 *

Full-text access for editors Access for subscribers Purchase this article Comment on this article