Investigation Of Diamond Like Carbon Thin Film Deposited By Coupling DC/RF Magnetron Sputtering

Diamond like carbon films(DLC)are a form of amorphous structure material.DLC films are currently used as ablation materials for ICF target in the study of inertia confinement fusion(ICF)experiment because of their excellent properties of thermal stability and optical transparency,the higher strength,and compact microstructure.With the development of domestic ICF experiment,DLC films with higher thickness,high mass density,smoothness surface and excellent mechanical property are required.Therefore,it is very important to study and discuss the influencing factors on mass density,surface roughness,internal stress and the fabrication of the Si/DLC microshells.In this paper,we deposited DLC films by coupling DC/RF magnetron sputtering,the films structure and properties are investigated in detail.The influence of deposition parameters on growth rate was discussed.Beside,FTIR spectroscopy,Raman spectroscopy and XPS were used to study the structure and chemical bonding of the samples deposited at different preparation parameters.Nanoindentation with continuous stiffness measurement(CSM)tests was performed for the DLC films prepared by different deposition parameter in order to investigate the hardness and modulus of the DLC films.AFM and FE-SEM were employed to investigate morphology and roughness of the films.The XRR measurement was utilized to analyze the film density,which was carried out on high resolution PHILIPS MRD using the CuKα1 emission.The internal stress of the films was evaluated by substrate curvature method.Specifically,thickness of the films and curvature of the Si wafers before and after deposition of the films were measured using a Micro XAM 3D non-contact surface profilometer,and the internal stress was calculated by Stoney equation.By the systematic studies above,four main conclutions can be made as following.It has been developed in the aspect of fabrication the microspheres.(1)The influence of working pressure on structure and properties of DLC films.It was found that as the working pressure increased,the deposition rate decreased gradually and the sp~3 content in the films first increased then decreased;the surface roughness presented a trend that first decreased then increased and gained the minimum surface roughness which is 6.68nm at the working pressure of 1.OPa.With the pressure increasing,both hardness and modules of films first increased then decreased,and reached the maximum value of 11.6GPa and 120.7GPa respectively at the work pressure of 1.0Pa.(2)Effect of hydrogen flow on structure and properties of DLC films.It is found that the deposition rate decreases,while the sp~3 content in the DLC films increases with the hydrogen flow increasing.When the hydrogen flow is at 25 mL/min,the sp~3 content reaches 36.4%,the hardness and modules of films reach the maximum value of 17.5 GPa and 137 GPa,respectively.The internal stress of DLC films prepared at different hydrogen flow is less than 0.5 GPa.The coupling DC and RF reactive magnetron sputtering may be really an effective method to prepare high quality thick DLC films with low internal stress.When the hydrogen flow increases,the surface of the DLC films becomes more denser and smoother,the surface root mean square roughness decreases from 5.40 nm to 1.46 nm.(3)Effect of DC voltage on structure and properties of DLC films.It was found that the deposition rate decreases,while the content of sp~3 first increases and then decreases with the DC voltage increasing.The sp~3 content inside the film reaches maximum value 29.3%at DC voltage of 500 V.The hardness and modules of films reach the maximum value of 17.5 GPa and 137 GPa respectively at DC voltage of 500 V.Film with the densest microstructure,and the smallest surface roughness value was also obtained at 500 V.All films exhibit relatively high mass density(2.25-2.36 g/cm3)and low internal stress(lower than 0.3 GPa)compared with some results published by other researchers.(4)The preparation of Si/DLC microsphere.When DC voltage at 500V,RF power at 50W,working pressure at 1.0Pa,Ar flow at 50sccm,we can deposite DLC film with 50um and smooth surface on 2mm Si microsphere which was placed into device of microspheres coating vibration.In summary,the DLC films were succuessfully deposited by coupling DC/RF magnetron sputtering.The structure,component and properties of DLC films were analyzed systematically.The results show the DLC with high mass density,low internal stress and well mechanical properties will prepare material which satisfy the requirement of ICF physics experiments.