| SiO2 film has excellent chemical stability and electrical insulation properties.According to different needs,people have used SiO2 film as the gate oxide layer of metal oxide semiconductor field effect transistor（MOSFET）,the protective layer of the device and capacitors dielectric film.The properties of SiO2 film are related to the preparation process.The general preparation methods of SiO2 films include chemical vapor deposition,physical vapor deposition and thermal oxidation.In this paper,SiO2 thin film were prepared on substrate Si（100）by electron cyclotron resonance（ECR）hydrogen and oxygen mixed plasma at low temperature.This process is achieved through ESPD device.This device can provide high activity and high ionization rate’s oxygen active particles by microwave electron cyclotron resonance,which can greatly reduce the oxidation temperature.In this paper,the oxidation temperature,O2 flow rate and the ratio of O2 and H2 on the growth rate of SiO2 thin films were studied.In addition,the insulating properties of SiO2 films and the defect density at the interface were characterized by electrical tests.The experimental results show:The thickness of SiO2 film shows a linear trend with the increase of temperature,and it means that the oxidation rate shows an increasing trend with the increase of temperature.Therefore,the optimum oxidation temperature of 500 ℃ is determined.The increase of O2 flow shows a tendency to increase first and then decrease,and when the O2 flow rate is 120 sccm,there is the maximum value and it means the oxygen plasma’s density and the microwave power to achieve the best match.Therefore,the optimum O2 flow rate is 120 sccm in this experiment.Adding the right amount of H2 in the oxidation process can further improve the growth rate of SiO2 film,but H2 flow is too high or too low are not conducive to the preparation of SiO2 film.Finally,the optimum experimental conditions were obtained as under the O2 flow rate of 120 sccm,the H2 flow rate is 3 sccm.The results of I-V show that the introduction of H2 can improve the breakdown filed strength of SiO2 thin films by 13MV/cm,which is close to the ideal value of SiO2 film prepared by low temperature oxidation of ECR.Which will extend the working life of MOSFET devices.The results of C-V show that the sample’s hysteresis of capacitor is not obvious and it means the introduction of H2 can improve the performance of SiO2 thin films. |
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