The Influence of a TiN Film on the Electronic Contribution to the Thermal Conductivity of a TiC Film in a TiN-TiC Layer
- PDF / 1,273,901 Bytes
- 10 Pages / 593.972 x 792 pts Page_size
- 67 Downloads / 137 Views
TION
THERMAL conductivity (K) of metallic ceramic carbides and nitrides has been studied extensively.[1–3] These include TiC, ZrC, and HfC and TiN, ZrN, and HfN[4] of group IV metals. Of these, detailed investigation has been carried out on K of TiC and TiN[1–3] to determine the effect of C and N deficiency, respectively, scattering electrons, and phonons by vacancies and temperature dependence.[2,3] The main features are that both electronic (Ke) and phonon (Kp) contributions are present for TiC, but only Ke is present for stoichiometric TiN.[5] The lower value of x in TiCx or y in TiNy increases residual electrical resistivity.[1] The value of K becomes higher for higher values of x and y, but remains nearly constant for stoichiometric TiN at higher temperature (above room temperature or > 27 C). Scattering of carriers of heat (electrons and phonons) by vacancies is present at higher temperature (> 27 C) so that both Ke and Kp are reduced for lower values of x and y. TiC and TiN films are used as diffusion barrier films[6] in electronic devices and as hard coatings in machine tools.[7] Therefore, Ke and Kp and interface thermal K. JAGANNADHAM is with the Materials Science and Engineering Department, North Carolina State University, Raleigh, NC 276957907. Contact email: [email protected]. Manuscript submitted July 20 2017
METALLURGICAL AND MATERIALS TRANSACTIONS A
conductance h between the films are important parameters in the dissipation of heat. In the present work, the values of Ke, Kp, and h are determined in samples with different values of x and the thickness of the individual layers of TiC and TiN. Diffusion of C and N across the interface between TiC and TiN is found to reduce the interface thermal conductance h. More importantly, the value Ke in TiC is found to be significantly increased in the presence of TiN film. In order to determine the influence of a layer on the thermal conductivity of another layer in a layered composite, it is necessary to choose two layers with different heat carriers. For example, the thermal conductivity of TiN is completely electron mediated, while that of TiC is both phonon and electron mediated but with phonon domination. However, these two contributions will change in the presence of the TiN layer. As a result, the influence of TiN on the phonon and electron mediated thermal conductivity of TiC is evaluated when TiC film is grown on TiN. In the present work, these contributions to the thermal conductivity of TiC are evaluated in the presence of TiN film. These results will be useful in the evaluation of thermal conductivity of many layered composites. Therefore, the results of the present work have significant importance in the evaluation of thermal conductivity of composites.
II.
EXPERIMENTAL
Polished Si wafers of (001) and (111) orientation were cleaned with acetone and etched in 49 pct HF for 3
minutes and rinsed with DI water and dried. The wafers were used as substrates for deposition of TiC and TiN films. TiN and TiC films were deposited sequentially by reactive magnet
Data Loading...
