Low temperature metallorganic chemical vapor deposition routes to chromiummetal thin films using bis(benzene)chromium

Different routes to control carbon incorporation into Cr-based coatings gro wn by metallorganic chemical vapor deposition (MOCVD) using Cr(C6H6)(2) as precursor have been explored. In agreement with partial equilibrium thermod ynamic calculations, the reduction and even the suppression of carbon incor poration into the chromium layers from the decomposition of the input gas m ixture Cr(C6H6)(2)/H-2 is possible only under or near atmospheric pressure. However. these deposition conditions do not allow for the development of a process for large scale applications since they lead to a poor uniformity and a low growth rate of the metal thin films. Hard chromium metal coatings are more conveniently deposited at low temperature (623-673 K) by addition of small amounts of C6Cl6 to the input gas phase. This MOCVD process opera tes at low pressure even with the use of inert carrier gas unlike the first route. Under these conditions, a good throwing power is obtained leading t o a promising process for industrial applications. The influence of the gro wth conditions on the properties of the films is described, and some proper ties of the chromium coatings are presented. Interestingly, they exhibit a very high hardness (similar to 21 GPa) and good adhesion to steel substrate s. A growth mechanism supported by on-line mass spectrometry analyses is di scussed. The C6Cl6 molecules favor a reaction pathway which is not expected on the basis of predictions from thermodynamic calculation. The successful growth of vanadium metal thin films from bis(benzene)vanadium and C6Cl6 un der related conditions suggests that the proposed mechanism may be extended to the deposition of other transition metals starling from their bis(arene )metal complexes as precursors. (C) 1999 The Electrochemical Society. S0013 -4651(99)02-013-3. All rights reserved.