Study On Preparation Of Indium-Gallium-Zinc Oxide Thin Films And Microstructure Changes Of Sputtering Target

The indium gallium zinc oxide?IGZO?thin film has the advantages of high transmittance,wide optical band gap,high electron mobility and low temperature preparation process,etc.It is a transparent conductive oxide?TCO?material with development prospects,which can be applied to TFT devices with higher transmittance,greater resolution,and lower power consumption,and it is a key substrate for the preparation of high-end display screens such as OLED?Organic Light-Emitting Diode?,flexible,and large LCDs.The process parameters of the IGZO thin film prepared by magnetron sputtering have greatly affected the quality of the thin film.The optimization of preparation parameters of magnetron sputtering process is very important to obtain high-performance IGZO TFT devices.So far,few domestic studies on IGZO targets and films have been done,which limits the application and localization of IGZO materials.Therefore,this paper systematically studied the influence mechanism of sputtering gas pressure,sputtering power and substrate temperature on the microstructure,morphology,photoelectric performance and chemical valence state of the film,and explored the best preparation process of IGZO film by controlling the quality factor parameter.In addition,based on the interaction mechanism between the IGZO film and the performance of the target before and after sputtering,the microscopic changes of the target before and after sputtering were studied.The phase composition,microstructure,cracking and nodulation of the IGZO target before and after sputtering were carried out.Furthermore,the center area,the etched area and the edge area after sputtering were selected for detailed study.The main research results obtained are as follows:?1?As the sputtering gas pressure increased from 0.2 Pa to 0.8 Pa,the root mean square roughness and resistivity of the film decreased first and then increased.When the sputtering pressure was 0.4 Pa,the film had a lower root mean square roughness?0.204 nm?and the resistivity value(4.012×10^-3?·cm).The optical transmittance and quality factor of the film increased first and then decreased.When the sputtering pressure was 0.4 Pa,the film had the best average transmittance?89.06%?and the quality factor value(26.38×10^-4?^-1).?2?As the sputtering power increased from 60 W to 120 W,the sputtering rate,optical band gap and quality factor of the film gradually increased,and the surface roughness and resistivity of the film gradually decreased.When the sputtering power was 120 W,the sputtering rate,optical band gap and quality factor reached maximum values,which were 18.20 nm/min,3.83 e V,and 14.26×10^-4?^-1,respectively.The surface roughness and resistivity of the film gradually decreased.When the sputtering power was 120 W,the root mean square roughness and the resistivity of the film reached the minimum values of 0.185 nm and 9.028×10^-3?·cm,respectively.?3?As the substrate temperature increased from room temperature to 300?,it can be found that the films prepared at different substrate temperatures showed amorphous structure.Considering the quality factor,film roughness and the high temperature resistance of flexible substrates,the best preparation temperature was revealed.When the substrate temperature was room temperature,the quality factor of IGZO film,the average transmittance in the visible light range and the optical band gap had larger values of 28.66×10^-4?^-1?86.69%and 3.842 e V,respectively.And the root mean square roughness and resistivity have smaller values of 0.32 nm and2.919×10^-3?·cm,respectively.?4?The target before sputtering consisted of the main phase In₂Ga₂Zn O₇ and the secondary phase Zn Ga₂O₄.Targets in different regions after sputtering contained different types of nanoparticles,and the central region and the etched region were mainly composed of In₂Ga₂Zn O₇ and gallium-rich oxide.In addition,the nodule in the center area was rich in Ga element and also contains higher C element?caused by dust and shedding in the sputtering chamber?.The contaminant C easily accumulated in cracks and holes,becoming the core of nodulation;the edge region was mainly composed of In₂Ga₂Zn O₇.At the same time,it was also found that the uneven distribution of the chemical composition of the target after sputtering would further expand the nodules on the surface of the target.