Microstructure, Stress and Texture in Sputter Deposited TiN Thin Films: Effect of Substrate Bias

Abstract

Abstract:Titanium nitride thin films deposited by reactive dc magnetron sputtering under various substrate bias voltages have been investigated by X-ray diffraction. TiN thin films exhibits lattice parameter anisotropy for all bias voltages. Preferential entrapment of argon atoms in TiN lattice has been identified as the major cause of lattice parameter anisotropy. Bombardment of argon ions during film growth has produced stacking faults on {111} planes of TiN crystal. Stacking fault probability increases with increasing substrate bias voltages. X-ray diffraction line profile analysis indicates strain anisotropy in TiN thin films. Diffraction stress analysis by d-sin 2 ψ method reveals pronounced curvature in the plot of interplanar spacing (d) (or corresponding lattice parameter (a)) versus sin 2 ψ. Direction dependent elastic grain interaction has been considered as possible source of the observed anisotropic line broadening. IntroductionTitanium nitride (TiN) thin films deposited by reactive magnetron sputtering is widely used for improving the hardness and wear resistance of materials surfaces [1]. Such functional properties critically depend on the microstructure of TiN thin films. It is well known that ion bombardment during thin film deposition can change the microstructure of such hard coating [2][3][4]. During the films deposition, the substrate is negatively biased (with respect to deposition chamber) so that the positively charged ions of the sputtering gas such as argon can be accelerated towards the substrate during the film growth. Negative bias voltage of the substrate can be varied in order to change the energy of the bombarding ions which is the key to change the film microstructure. In the present work, microstructure of TiN thin films deposited at various substrate bias voltages has been studied by X-ray diffraction. Intrinsic/growth stresses and crystallographic textures in TiN films have been studied as a function of substrate bias voltages (i.e. energies of the bombarding ions). Specimen preparation and characterizationPolycrystalline titanium nitride thin films (thickness ~ 2µm for all films) were deposited on silicon ({100} Si) substrate by planer reactive dc magnetron (magnetron power ~ 270W) sputtering under various substrate bias voltages (0kV to -5kV) using a high voltage pulsed DC power supply. The sputter target was 99.99% pure titanium and argon gas of high purity (99.99%) was used as the sputtering gas for the magnetron targets. For the reactive deposition of titanium nitride, the reactive gas nitrogen was introduced. Operating pressure of the sputtering chamber was 3x10

Optical Properties and Microstructure of TiNxOy and TiN Thin Films before and after Annealing at Different Conditions

“…TiN, the most popular transition metal nitride, has a golden color and is characterized as an extremely hard material, with a high melting point (2950 • C), high thermal and chemical stability at elevated temperatures, and ease to manufacture as compared to TiN x O y [11,12]. Several studies investigated the structure evolution and electrical properties of TiN thin films produced by different deposition parameters [13][14][15][16][17][18][19][20]. Several researchers have suggested [10,[21][22][23][24] that TiN may be used as an absorber layer for high-temperature applications; however, limited work appears in literature on the optical properties of TiN as a selective absorber [21][22][23][24].…”

Role of the Three-Phase Boundary of the Platinum–Support Interface in Catalysis: A Model Catalyst Kinetic Study

“…Figure shows the natural logarithm of the TOF (ln­(TOF/Hz)) versus the inverse temperature (Arrhenius plot) for reaction over the four Pt/YSZ samples and two Pt/Al 2 O 3 samples (samples 1PtAl 2 O 3 and 400PtAl 2 O 3 ) and over the Pt/zirconia (Pt/ZrO 2 ) and Pt/Al 2 O 3 samples used by Contreras et al (it was not possible to extract rate data from the work of Ryll et al) . In the Arrhenius plot we mark the limit where the maximum temperature difference between the sample and the gas phase is expected to be 11 K. As Conteras et al indicated, their data points lie in the regime above the light-off point where heat transfer limitations are expected.…”

“…A low-intensity peak and shoulder to the left of the Pt(111) reflection can be attributed to trace amounts of material with argon implanted into the Pt(111) plane. This is a common phenomenon associated with the sputtering process …”

“…This is a common phenomenon associated with the sputtering process. 20 It is possible that there could be contamination of the Pt surface in the region of the three-phase boundary as a result of the ablation process. Such contamination could be catalytically significant and is difficult to characterize, as what constitutes a catalytically significant level of contamination is unknown.…”