Four main forming methods for ITO target material

As we all know, ITO sputtering target is a black gray ceramic semiconductor formed by mixing indium oxide and tin oxide powder in a certain proportion in a high temperature atmosphere (1600 degrees, oxygen sintering) through a series of production processes.  ITO target was used as raw material to oxidize ITO film to glass substrate or flexible organic film by magnetron sputtering.  ITO film has conductivity and light transmission, and its thickness is generally 30nm ~ 200nm.  

There are four main forming methods for ITO target:  

Vacuum hot pressing is a process to densify ceramic materials by using heat energy and mechanical energy, which can produce ITO ceramic targets with a density of 91% ~ 96%.  The process is as follows: heat the mold, add the sample, attach the mold to the heating plate (control the melting temperature and time), then melt the sample, harden it, cool it, and finally take out the finished product.

Hot isostatic pressing (HIP) can be considered as pressure sintering or high temperature pressing.  Compared with traditional press-free sintering, hot isostatic pressing can make the material completely compact at a lower temperature (generally about 0.5 ~ 0.7 times the melting point of the material).  It can control the structure well, restrain grain growth and obtain uniform and isotropic structure.  The process of ITO target preparation by hot isostatic pressing is as follows.  Firstly, ITO solid solution powder was partially reduced in a certain reducing atmosphere (such as a mixture of H2, N2 and H2) and at 300-500 ℃.  The reduced powder is then pressed into preforms by molding or cold isostatic pressing.  The preforms are placed in stainless steel containers with insulation between them.  The container is then vacuumed and sealed.  Finally, ITO target material was prepared by placing the container in a hot isostatic pressure furnace at 800 ~ 1050℃ and 50 ~ 200MPa for 2 ~ 6 hours.  

Room temperature sintering is a target preparation method developed in the early 1990s.  It uses the precompression method (or slurry casting method) to prepare the high-density target prefabricated, and then sintering under a certain atmosphere and temperature.  The main process of atmospheric sintering method is: the In2O3 powder (with a certain vibration density) and SnO2 powder mixed, prepared into slurry casting slurry.  It is then dehydrated and defatted for a long time at 300 ~ 500℃, and finally sintered in pure oxygen or air atmosphere at a pressure of more than 1 atmosphere at a sintering temperature of 1450 to 1550 °C.  

Cold isostatic pressing (CIP) takes rubber or plastic as cover material and liquid as pressure medium to deliver super high pressure at room temperature.  Under the protection of low pressure oxygen atmosphere, ITO powder was pressed into large ceramic prefabricated rod by cold isostatic pressing, and then sintered at 1500~1600℃ in the pure oxygen environment of 0.1~0.9 MPa.  This method can theoretically produce ceramic targets with a density of 95%.