Research On Growth And Resistence-temperature Properties Of SiC Thin Films Deposited By RF Magnetron Sputtering

As the third-generation wide bandgap semiconductor materials,SiC has a series of characteristics such as high thermal conductivity,high saturation electron drift velocity,high bandgap width,high breakdown electric field and high thermal stability.So it has a broad application prospects in aviation,nuclear power and high-power,high-frequency device.In this paper,we choose single crystal <100>Si and single crystal <0001>sapphire(?-Al2O3)as the substrate,and then fabricate hexagonal SiC films with different application conditions by RF magnetron sputtering.The effects of different process conditions on the phase structure,surface and cross-sectional morphology,and resistance-temperature properties of the films were investigated.The comprehensive electrical properties of the films on different substrate were also summarized.SiC thin films were grown on <100>Si and <100>Si/SiO2(200nm)substrates by RF magnetron sputtering.On the <100>Si/SiO2(200nm)substrate,the lattice mismatch between the thin film and the substrate was released to some extent at the deposition temperature of 750? by adjusting the process parameters such as transition layer,deposition temperature and annealing,and a type of hexagonal SiC film with a certain orientation was obtained.The activation energy of the thin film is 0.16 eV,which is dominated by the extended state conduction mechanism.Excessive deposition or annealing temperature will both cause the diffusion of Si and C atoms in the SiC film,resulting in heterogeneous phase,affecting the density and resistance-temperature stability.At the same time,the SiC film has a very high thermal constant B(1400~2000K)at-100~250?.The error of resistance at different temperatures was found to be <±5% after repeated cycling test,suitable for making high-precision type thermistor and temperature sensorIn order to apply the electrical characteristics of the SiC thin film at a higher temperature,SiC thin films were grown on <0001>sapphire substrate by RF magnetron sputtering.When the deposition temperature is 750?,the pure argon pressure is 1Pa,the RF power is 100 W,and the annealing temperature is 1000? in Ar for 10 min.The XRD diffraction shows the films are the 6H-SiC.However,due to the large tensile stress of the substrate,the lattice distortion and the diffraction peak of the thin film are shifted by 1~2°in the small angle direction.The conductive mechanism of the film is biased towards the extended state conduction,and the activation energy is 0.21 eV.At the same time,the resistance variation range of this SiC film is-100~425?,and the variation range of thermal constant B is large(960~4500K).The error of resistance at different temperatures was found to be <±8% after repeated cycling test,suitable for making high-temperature type thermistor and temperature sensor.In order to alleviate the lattice mismatch and the difference of thermal expansion coefficient between SiC thin film and sapphire substrate,a type of Si-O-C intermediate layer was deposited between the sapphire substrate and the SiC thin film by RF magnetron sputtering,which reduced the diffraction peak of SiC film about 0.2 ~ 0.4 ° to small angle.And the thin film can grow more stably,thickness increases about 0.1?m.The variation trend of activation energy and resistance-temperature characteristic of the film are not changed.The membrane-based bond strength of the transition layer is 1N higher than that of the film without the transition layer.