Effect of Annealing on Hardness and Elastic Modulus of Invar36 Thin Films Deposited by Direct Current Sputtering for Strain Gauge Applications

Invar36 thin film was deposited at room temperature on p-type silicon (100) substrates using DC magnetron sputtering technique. In order to investigate the post-annealing effect on the structural characteristics and mechanical properties of the prepared films, they were vacuum annealed for one hour at different temperatures viz. 200°C, 400°C and 500°C. Composition analysis, phase structure, microstructure and roughness of as-deposited and annealed Invar36 thin films were investigated by energy dispersive X-ray analysis (EDX), X-Ray diffraction (XRD) and Atomic Force Microscopy (AFM). Mechanical properties of Invar36 thin films were studied by nano indentation method. EDX analysis revealed a variation in nickel content with annealing. The XRD measurements indicated the phase transformation of Invar36 thin film with annealing. AFM analysis implied uniform surface morphology of the films, increase of surface roughness and grain size with annealing. The hardness (H) of the film decreased with annealing. Hardness of as-deposited, annealed at 200oC, 400oC and 500oC were found as 8.5±0.96 GPa, 7.64±0.35 GPa, 6.34±0.14GPa and 3.95±1.05 GPa, respectively. The elastic modulus of Invar36 thin films was increased with annealing. Elastic modulus of as-deposited, annealed at 200oC, 400oC and 500oC were found as 157.00±25.49 GPa, 166.0±11.8 GPa, 172.00±9.93 GPa and 176.00 ±10.78 GPa, respectively. These results are explained on the basis of the change of microstructure after annealing and the effect of the same on the mechanical properties of Invar36 thin films for strain gauge applications

Growth and effect of deposition pressure on microstructure and electrical properties of 3C-SiC thin films deposited using methyltrichlorosilane single precursor

This paper presents effect of deposition pressure on the microstructure and electrical properties of 3C-SiC (111) thin films. These films are deposited at a temperature of 1040 ◦C and pressures of 1.5, 1.8, 2.5 and 2.7 mbar, on thermally oxidized Si (100) substrates from a mixture of methyltrichlorosilane and hydrogen gas using a vertical hot wall, low pressure chemical vapour deposition (LPCVD) reactor. The above properties are investigated for all films using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and four probe technique. An FTIR spectrum shows the formation of Si-C bonding of deposited films. The SEM and XRD investigations show improvement in the grain size and crystallanity, decrease in strain and dislocations of the films with increase in the deposition pressure from 1.5 to 2.5 mbar. AFM investigations show decrease in roughness of the films with increase in the deposition pressure from 1.55 to 2.5 mbar. The sheet resistance of 3C-SiC thin films is found to decrease with increase in temperature in the range of 35 to 550 ◦C. Comparing all the films, 3C-SiC thin films deposited at a pressure of 2.5 mbar and temperature of 1040 ◦C exhibited improved structural and electrical properties

Influence of annealing and thickness on the electrical properties of invar36 thin film for strain gauge applications

Invar36 thin films with various thicknesses from 200 °Ato 1400°Aare deposited on glass substrates by DC magnetron sputtering technique. After deposition, the samples are annealed in vacuum ambient (10−5mbar) upto 500◦C. Electrical properties of as-deposited as well as annealed films are analyzed with respect to thickness and annealing temperature. In situ measurement of sheet resistance of films with respect to annealing temperature is carried out by four probe technique. There is a decrease of sheet resistance and resistivity of all films with increasing temperature irrespective of film thickness.The resistivity of the as deposited films is around 230 mW-cm and decreases with increasing temperature and found as 84 mW-cm for 550°Afilm annealed at 500◦C. Temperature co-efficient of resistance (TCR) of films at different temperature is measured and is found to be in the range of 10−4/ ◦C.Gauge factors of as deposited and annealed at 300◦C and 500◦C films are measured by using four point bending technique and it is found that gauge factor decreases with respect to annealing temperature irrespective of film thickness. The best characteristics among different thickness and annealing temperature are obtained at 500◦C, for the films of thicknesses between 400 °Ato 600 °A