Study On The Preparation And Properties Of Film Resistor With Low TCR Based On TaN

This research is based on the fact that there is a large gap in the quality of Ta N film resistor between our country with the world.The preparation technology,power characteristic and oxidation characteristic of Ta N film resistor were completely investigated in this paper,aiming to fabricating Ta N film resistor with high performance by controlling TCR and thermal oxidation.Details are as follows:(1)The effects of sputtering power,N2 partial pressure and sputtering pressure on microstructure and electrical property were studied,respectively.The results show that:(1)the increase in sputtering power from 150 W to 350 W contributes to the increase in grain size.Rising grain size will result in the decrease in resistivity and the increase in TCR.(2)When the N2 partial pressure increases from 0% to 9%,Ta-N phases appears in films in an order of Ta(including ?-Ta and ?-Ta),Ta N0.4,?-Ta N,?-Ta N and Ta4N5.The film resistivity increased from 138 ??·cm to 1052 ??·cm,and the film prepared at a N2 partial pressure of 5% had a minimum TCR of-28 ppm /°C.(3)The ratio of N/Ta atoms in the film composition,the TCR and resistivity of the films increases with the increase of sputtering pressure.At 0.3 Pa,the prepared film had a minimum TCR of 41 ppm /°C.The preparation parameter for superior Ta N films was obtained by orthogonal experiment,and the fabricated Ta N films have the TCR of 26 ppm/?.(2)Ta N film resistor with the rated power density of 9 W/mm2 was fabricated.The investigation on themal oxidation suggests that the percentage of resistance variation caused by thermal oxidation was less than 0.5% unless the ambient temperature is less than 100?.A method of using Ansoft ephysics software to assist in designing resistive power is proposed.Through the thermal simulation of the film resistors,the relationship between the surface temperature and the load power density of the resistive film at different ambient temperatures is established.The power density of the load can be determined by the environmental conditions used in the design of the resistors.(3)Resistor 1 used in the ambient temperature of 25? with the rated power of 5 W and Resistor 2 used in ambient temperature of 70? with the rated power of 5W were designed and fabricated for use in the microwave circurt of DC~8GHz through adopting the results in(2).At the loaded power of 5 W,the temperatur of Resistor 1 and Resistor 2 are 95? and 112?,respectively.The difference surface temperature measured value and the simulation value is not large,indicating that the use of ephysics simulation to establish the surface temperature and load power density curve to assist the design of the power with the feasibility.The test results for microwave charateristic shows that S11 of Resistor 1 and Resistor 2 were less than-10.3 d B and-14 d B,respectively,and VSWR of Resistor 1 and Resistor 2 were less than 1.37 and 1.34,respectively,all showing great microwave charateristic in the frequency of DC~8 GHz.