AVS 46th International Symposium
    Thin Films Division Monday Sessions
       Session TF+VM-MoM

Paper TF+VM-MoM6
Gas-phase Chemistry in Up-scaled Plasma Enhanced MOCVD of TiN and Ti(C,N) on Plasma Treated Tool Steel

Monday, October 25, 1999, 10:00 am, Room 620

Session: Advances in Hard and Superhard Coatings I
Presenter: J.P.A.M Driessen, TNO Institute of Applied Physics, The Netherlands
Authors: J.P.A.M Driessen, TNO Institute of Applied Physics, The Netherlands
A.D. Kuypers, TNO Institute of Applied Physics, The Netherlands
J. Schoonman, Delft University of Technology, The Netherlands
Correspondent: Click to Email
In this paper, the deposition of TiN and Ti(C,N) in a relatively large scale reactor vessel is discussed. Tetrakis(dimethylamine)titanium (TDMAT) and tetrakis(diethylamine) titanium (TDEAT) were used for the purpose of depositing TiN and Ti(C,N) at low temperatures. In large scale systems, homogeneous reactions dominate the deposition process resulting in non-uniform and non-adherent coatings. However, in this study, favourable gas-phase conditions for deposition of Ti(C,N) from in a pulsed DC-plasma have been determined, making use of mass and optical spectroscopy. Decomposition of TDMAT in a pure hydrogen plasma results in the favourable cleavage of dimethylamine from TDMAT but prevents the formation of Ti(C,N) due to the lack of nitrogen and carbon. Addition of N@sub 2@ to the hydrogen plasma results in the formation of NH@sub x@ (1@<=@x@<=@4), opening transamination pathways. Results suggest that transamination plays an important role in the gas-phase of our system. Furthermore, these results were compared with those obtained from using ammonia. However, the depletion of TDMAT by interaction with nitrogen in a H@sub 2@(85%) - N@sub 2@(15%) plasma proceeds in a mechanistic step with a rate constant of k = 4.7 x 10@super -14@ cm@super 3@ mol@super -1@sec@super -1@. Nevertheless, seemingly high quality Ti(C,N) coatings were deposited on blank WN1.2370 tool steel and WN 1.2379 treated in a N@sub 2@/H@sub 2@ plasma. XRD analysis of the plasma treated substrate indicates the presence of CrN, among other species in the top surface layer. These multi-layer coatings, deposited at temperatures between 473 K and 698 K, increased in surface roughness, however, showed good adherence and optimum hardness. Hardness values varied from 1600 Hv to 2000 Hv.