Study On Composition And Microstructure Of Multi Ratio IGZO Targe

In recent years,with the rapid development of flat panel display technology,the higher requirements of materials have been put forward for the filed.Amorphous indium-gallium-zinc?IGZO?thin film is the key material of thin film transistor in flat panel display.Compared with the thin film transistors fabricated by?-Si and LTPS?Low Temperature Poly-Silicon?,IGZO thin film transistor has many obvious advantages,such as low leakage current,high carrier mobility and higher on-off ratio.Therefore,IGZO materials have important application prospects in new display technology.However,the quality of multi-component IGZO target is not easy to control,and the key technologies are mainly mastered by foreign manufacturers,so it is necessary to study its preparation,microstructure and properties systematically.In this study,IGZO targets were prepared by powder metallurgy technology,and the element ratio of IGZO targets was changed.The relationship among the composition,process and properties of IGZO target was studied systematically by controlling the element content and sintering temperature.In the experimental scheme,XRD,SEM,TG-DTA and four probe analysis methods were used to analyze the pretreatment of IGZO powder,molding process and sintering results.The internal relationship is analyzed by the study of the related mechanism of the composition,microstructure and performance of the target material,which provides theoretical guidance for the preparation of IGZO target with excellent performance.The main conclusions are as follows:?1?The ball milling process of IGZO powder and its influence on sintering were studied.The effects of mechanical ball milling on the morphology,phase composition,particle size distribution and specific surface area of IGZO mixed particles was studied,and the optimum powder state of sintered IGZO ceramics was analyzed.The results showed that the milling time has no effect on the phase of IGZO powder.After ball milling for more than 36 hours,the particles of IGZO powder were further refined,the particle size difference between the particles was significantly reduced.The uniformity,particle size distribution and specific surface area of IGZO powder were greatly improved.?2?The granulation process and mechanism of IGZO powder were studied.The influence of solid content and binder content on the micro morphology and pressing performance of IGZO granulated powder was analyzed,it is concluded that when the solid content is 60%and binder content is 1%,IGZO agglomerates with high sphericity,good uniformity and excellent pressing performance can be obtained.At the same time,it was found that the granulated powder with low solid content and low binder content was easy to produce pit and breakage,which led to the decrease of the pelletizing rate of the powder.?3?The pressing properties of IGZO powders with different molar ratios and the shrinkage curves of green bodies were studied.By analyzing the density of four kinds of pelletized powder,it is concluded that the higher the proportion of ZnO powder,the lower the proportion of In₂O₃ powder and Ga₂O₃ powder,the better the compaction performance of the mixed pelletized powder,and the higher the relative density.Through the thermal expansion apparatus,the thermal shrinkage test of the raw material powder and the IGZO powder were carried out.The results show that the final shrinkage of ZnO was the lowest.For four kinds of IGZO green bodies,the final shrinkage of the target decreased with increasing ZnO content.?4?The effects of molar ratio and sintering temperature on the microstructure and composition of IGZO target were studied.Four kinds of IGZO target materials?In2O3:Ga2O3:ZnO=1:1:1,1:1:2,1:1:4 and 1:1:8?with different molar ratio,namely IGZO-111,IGZO-112,IGZO-114 and IGZO-118,were selected for experiments.The results show that IGZO-111 ceramics with low Zncontent were easier to densify,but the reaction process was delayed in the whole temperature range.The reaction temperature of IGZO ceramics with higher Zncontent was lower,but the densification rate was slower.?5?The effects of molar ratio and sintering temperature on the properties of IGZO target were studied.Four kinds of IGZO target materials with different molar ratio,namely,IGZO-111,IGZO-112,IGZO-114 and IGZO-118,were selected for experiments.The experimental results show that compared with other IGZO ceramics,IGZO-111 ceramics had the best sinter properties.When the sintering temperature was 1500?,the target has the lowest resistivity of 3.4 m?·cm.The densification was the highest,reaching 99.54%.The IGZO-111 target with high density and high conductivity was obtained.