Study On 3C-SiC Film Stripping Thechnology And Surface Passivation

The excellent material properties of 3C-SiC make it a promising application in high-temperature,high-frequency,high-power and anti-radiation electronic device applications.If the Si substrate is etched away from the Si/3C-SiC heterostructure to obtain a 3C-SiC filmand then transferred to a flexible substrate to make a flexible device or circuit,it can be applied to a wearable device or some special environment,and can expand the application of 3C-SiCthin film devices and circuits.The performance of SiC devices is not only related to the materialproperties,but also related to the surface state.The surface of a semiconductor deviceinevitably has an unsaturated dangling bond,these dangling bonds are generated by thebreakage of chemical bonds,and dangling bonds readily accept the surrounding charge or adsorbed impurities,all of which may introduce intrinsic energy state in the bandgap,thesurface state.The surface state will cause the Fermi level pinning band to bend.Passivation is an effective means to reduce the effect of dangling bonds on the semiconductor surface.In this paper,the peeling process technology of 3C-SiC thin films was investigated.The peeling of 3C-SiC flexible thin films was achieved by wet etching and anodic oxidation peeling respectively.The S passivation technology of 3C-SiC thin films was studied.The passivation effect of 3 passivation solutions on the surface of 3C-SiC films was analyzed.The main research contents and conclusions of this paper's work are as follows:1.In order to study the effect of wet etching process parameters on the peel integrity and peel area of the film,different proportions of isotropic and anisotropic etching fluids were selected.The experimental results show that the anisotropic corrosion rate is within 1.0?m/min.Although the film can be completely peeled off,the speed is ioo slow.The isotropic etching solution is shown in Table 3-1.The corrosion rate can be from 2.5 to 24.0 ?m/min.The rate of reaction can be slowed by controlling the ratio of increasing CH3COOH and decreasing the proportion of HNO3.If the corrosion rate is too high,it will easily cause the film to crack,and it cannot be peeled off to obtain a complete film.Therefore,HF:HN03:CH3COOH=1:1:1 is better stripping process parameter.2.The anodizing stripping process parameters of 3C-SiC thin films were studied by means of anodized etching technology.By analyzing the effect of different anodizing time on the surface and cross-sectional morphology of Si/3C-SiC samples,it is found that the anodizing time has little effect on the surface of 3C-SiC,and no porous structure appears on the surface of 3C-SiC film.However,as the anodizing time increases,the space between the Si substrate and the 3C-SiC film gradually increases,which gradually separates the film and the substrate.When the anodizing is performed for 40 minutes,the Si substrate and the 3C-SiC film are completely separated.Photoluminescence studies show that as the etching time increases,the luminous intensity of the luminescence peak after 600 nm becomes stronger and stronger,this is because as the 3C-SiC thin film gradually departs from the Si substrate,the Si substrate absorbs less and less photoluminescence of the 3C-SiC thin film.3.The effects of Si substrate on stress and photoluminescence in 3C-SiC films were studied.It is found that due to the lattice mismatch between Si and SiC reaching 20%,there is a large tensile stress in the 3C-SiC thin film grown on the Si substrate,and the tensile stress in the 3C-SiC thin film before and after the substrate is peeled off is reduced 22%;Annealing is also one of the methods to reduce the stress of the film.The stress analysis of the annealed 3C-SiC film shows that,the tensile stress existing in the 3C-SiC thin film with Si substrate after annealing is decreased by 44%compared with that before annealing,and the tensile stress in the 3C-SiC thin film after peeling off the Si substrate is decreased by 43%compared with that before annealing.Photoluminescence studies have found that all the emission peaks of the PL spectrum of the 3C-SiC thin film after the Si substrate is stripped have been enhanced,and a new luminescence peak has appeared at 412 nm,this is because when the 3C-SiC thin film is on a Si substrate,and the weak emission at 412 nm is completely absorbed by the substrate.The other luminescence peaks are also affected by the absorption of light by the substrate,while the substrate is enhanced by the luminescence peak.4.The influence of different components of S passivation solution on the passivation of 3C-SiC films was studied.The analysis shows that the Si-S bonds and C-S bonds are formed on the surface of 3C-SiC films after passivation with 3 kinds of passivation solutions,which indicates that the 3C-SiC films have formed effective passivation on the surface.The surface chemical bond analysis and photoluminescence results show that after the passivation of neutral(NH4)2S and NH3 � H2O mixed solutions,the Si-S bonds and C-S bonds on the surface of the sample are the strongest,and the luminescence peak intensity is the highest.It shows that the passivation solution can reduce surface state density and reduce surface recombination more effectively than other passivation solutions.