The Study of the Electrical Properties of the Ni-Cr Thin Film Resistor

• Main Authors: Nai-chuan Chuang, 莊乃川
• Other Authors: Jyi-Tsong Lin
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/tjm5d5

博士 === 國立中山大學 === 電機工程學系研究所 === 104 === With the demand of electronic devices increasing for information and telecommunication technologies, the passive component with high precision and high reliability properties have become more important in the recent years. The main process of thin film resistor is by sputtering technology to perform high precision of resistance, lower temperature coefficient of resistance (TCR) and high reliability properties. The thin film resistors are widely used in electronic circuit. Among the thin film resistor processes, the laser trimming dominate the precision of resistance and TCR is dominated by composition of sputtering target, sputtering condition and annealing condition. In this study, we focus on the dependence of TCR on different Ni-Cr film thickness and different annealing conditions. The electron mean free path (MFP) and scattering mechanisms of carriers due to surface scattering, grain boundary scattering and surface roughness scattering of Ni-Cr film have been determinate. The experimental results show the electron MFP is about 24.2nm. The TCR performance is increasing with annealing temperature increasing obviously for the thickness of Ni-Cr film is less than electron MFP. The TCR performance is stable as the Ni-Cr film thickness is thicker than the electron MFP, and decreases slightly as the annealing temperature increases. This is because the film is discontinuous with island structure which scattering of electrons at imperfections is dependent on temperature and the TCR increasing. For the thickness of Ni-Cr film is thicker than electron MFP, the film is continuous structure. There is a Cr2O3 oxidation layer on the surface of thicker Ni-Cr film after annealing process. An interdiffusion reaction phenomenon is occurrence. The Cr is diffused out to form Cr2O3 layer and caused higher Ni concentration in inside conductive layer. Thus the TCR decreased with the increase in annealing temperature. Finally, the electrical conduction mechanisms of Ni-Cr thin film resistor are demonstrated by different film thickness through scattering models fitting. The resistivity and temperature coefficient of the resistance of Ni-Cr thin film are measured to investigate the influence of thickness with different annealing temperature. An oxidation and atom inter-diffusion model was proposed to explain the effects of film thickness on the electrical properties of Ni-Cr thin film resistor under different annealing temperature. As the result, we obtained the thin film resistors of low TCR under ±5 ppm/0C at -55 0C and 125 0C.