Preparation and Block Resistance Uniformity of ITO/SiO2 Films with Double Film Layer
According to the product design principle,the double film structure of SiO2/ITO films was designed and prepared.The preparation process is as follows:Si target(purity 99.85％)was used,and ITO target(purity 99.85％)was mixed with 90％indium oxide(In2O3)and 10％tin dioxide(SnO2).TN(Twist Nematic liquid crystal)sodium-calcium glass substrate was selected,size 16"×14"×1.1 mm,one side coating.Through magnetron sputtering and continuous coating magnetron sputtering,production line test equipment was used to carry out process design for TN series glass,requiring block resistance uniformity range of 70-90 Ω/sq.,coating in a 10 000 clean workshop at control humidity of 30％-70％RH.The TN sodium-calcium glass substrate was placed on the frame,the height of the frame was approximately equal to the height of the coating equipment,and the frame was transported by the conveyor belt through the coating machine for coating.The first vacuum extraction treatment of the coating machine was carried out to ensure the stability of the atmosphere during the coating process,and then it was sent to the inlet chamber,transition chamber,variable speed chamber,and then the coating chamber for Si target and ITO target for coating.The deposited Si film was oxidized to form a SiO2 film,and after coating,it was sent to the variable speed chamber,transition chamber,and outlet chamber in turn to fill air for natural cooling to prevent the glass from being damaged due to the large pressure difference between inside and outside.The effects of target magnetic field intensity,coating work-piece moving speed and coating power on the film resistance uniformity of ITO/SiC2 films were studied by X-ray diffractometer(XRD),ST-21L film resistance tester,atomic force microscope(AFM)and FIB sample preparation transmission electron microscope(TEM).The phase,morphology and structure of ITO/SiO2 films prepared under optimized conditions were studied,and the effects of SiO2 films were discussed through element distribution analysis.The results showed that:(1)Under the optimized conditions of magnetron sputtering,when the magnetic field strength was 780-820 Gs,the motion speed of the coating work-piece was 1.2 m/min,and the coating power was 2.5 kW(A21)and 3 kW(A23),the minimum resistance range of ITO/SiO2 film was 10-11 Q/sq,and the average value was 75-76 Ω/sq.ITO/SiO2 film had the best film resistance uniformity.(2)ITO/SiO2 films showed the superposition of crystal spectral lines and amorphous spectral lines,and the characteristic peaks of In2O3 and SnO2 were slightly shifted to the left.The wide characteristic peaks of SiO2 indicated that SiO2 in the films was in an amorphous structure,and the grain size effect might partially occur,and then existed in the form of microcrystals or nanocrystals.(3)Compared with SiO2 films,the surface topography of ITO/SiO2 films was more uniform,more continuous,smoother and denser,and had an obvious double-film layer structure.The surface of ITO films was uniform and the film thickness was uniform,which was consistent with the uniformity of film resistance.The SiO2 film formed an interface layer with the ITO film and the glass substrate,which should also be the reason why ITO films had good bonding force;the loss of In element was blocked to some extent,which should be related to the amorphous structure of SiO2 in the film or the grain size effect,and the structure of poly crystalline ITO.In summary,the uniformity of ITO/SiO2 film resistance can be improved by optimizing the process factors such as the magnetic field strength of the target surface,the motion speed of the coating work-piece and the coating power,and the quality of ITO films can be improved by controlling the film forming quality of SiO2 films,and the loss of In element can be prevented.
magnetron sputtering methodITO/SiO2 double film layermicrostructureuniformity of block resistance
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