Phase evolution and sintering behavior of high-performance IGTO sputtering targets

Abstract

In-Ga-Sn-O (IGTO) targets are vital in preparing high-mobility IGTO thin film transistors. This study uses pressure slip casting and conventional sintering methods to prepare IGTO targets with three atomic ratios(IGTO-711 = 70:15:15, IGTO-712 = 70:10:20, IGTO-721 = 70:20:10 In:Ga:Sn at.%). With the increase of Ga content in the system, the phase composition of the IGTO targets changes from In₂O₃ and Ga_1.6In_6.4Sn₂O₁₆ to In₂O₃, Ga₂In₆Sn₂O₁₆ and GaInO₃. Their densification activation energy has been calculated using constant heating rate experiments. It shows that the activation energy is independent of the density in the relative density range of 0.70–0.85, and the activation energy is significantly affected by the ease of reaction of the physical phases. The densification activation energies of samples IGTO-711, IGTO-712 and IGTO-721 are 230.5 ± 42 kJ/mol, 926.4 ± 58 kJ/mol, 582.9 ± 52 kJ/mol, respectively. The presence of the GaInO₃ phase facilitates the densification process of IGTO targets. Ultimately, IGTO-712 targets with a relative density of 99.01 %, a resistivity of 0.42 mΩ cm, a microhardness of 1024.31 HV2, and a uniform grain size range of 3∼5 μm are achieved at 1450 °C for 20 h in an oxygen atmosphere.