AN EXPERIMENTAL-STUDY OF CHEMICAL-VAPOR-DEPOSITION OF TUNGSTEN ON TI TIN ADHESION BILAYERS - MECHANICAL-PROPERTIES/

The mechanical properties of chemical vapour deposited tungsten (W-CVD ) on Ti/TiN adhesion bilayers have been studied. Rapid thermal anneali ng (RTA) of the Ti/TiN bilayers has been found to strongly affect subs equently deposited W films. The stress in W is reduced as a consequenc e of the RTA treatment of Ti/TiN, and the stress reduction is especial ly pronounced for thin W films. However, the stress in the Ti/TiN bila yers deposited at 300 or 550 degrees C increases substantially after t he RTA treatment at 650 degrees C, leading to appreciable increase in the total stress of the whole Ti/TiN/W stack. The nucleation depositio n of W on the annealed Ti/TiN is somewhat hindered. The retardation of W growth on annealed Ti/TiN is discussed in terms of thermodynamics a nd classical nucleation theory in conjunction with the reduction of th e interfacial impurities (i.e. fluorine and oxygen) as a result of the RTA of Ti/TiN [A. Mouroux, R. Palmans, J. Keinonen, S,-L. Zhang, K. M aex, S. Petersson, in: Materials Research Society, MRS, San Francisco, CA, 1996], as well as the evolution of the W film texture with the W thickness. (C) 1998 Elsevier Science S.A.