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▼ [20p-234A-12] Effect of Atomic Layer Deposition Temperature on the Electrical Characteristics of Al2O3-passivated Amorphous InGaZnO Thin-Film Transistors
Keywords:a-IGZO TFT, DMAH, atomic layer deposition
Various passivation layers have been extensively explored to address the instability in oxide-based thin-film transistors (TFTs). Among the most utilized passivation layers, Al2O3 has been known to exhibit excellent barrier property against atmospheric gases such as O2 and H2O [1]. In this work, we investigated the effect of atomic layer deposition (ALD) temperature on the electrical characteristics of Al2O3-passivated a-IGZO TFTs employing dimethylaluminum hydride as precursor.
Bottom-gate a-IGZO TFTs were fabricated by sputtering 70 nm a-IGZO channel on SiO2/Si substrates, with Mo/Pt as source and drain electrodes. After atmospheric (N2:O2 = 4:1) annealing at 300C for 2 h, 25 nm Al2O3 passivation was deposited through ALD using DMAH at varying temperature from 100C to 300C. The passivated a-IGZO TFTs were finally annealed in O2 at 300C for 2 h. From the transfer curves obtained, decent TFT switching behavior is evident for all a-IGZO TFTs with DMAH-Al2O3 passivation. The summary of electrical characteristics also shows decreasing mobility at higher ALD temperature. This might be attributed to higher hydrogen content at lower temperatures that act as shallow donors and increase the mobility. Moreover, the results of positive bias stress test showed the smallest on-voltage shift of ~ 0.3 V at 200C and 250C. It is speculated that at an optimized ALD condition around 200C and 250C, the deposition temperature is not too low, which might result to incomplete Al2O3 formation, and not too high, which might cause possible degradation of precursor.
Bottom-gate a-IGZO TFTs were fabricated by sputtering 70 nm a-IGZO channel on SiO2/Si substrates, with Mo/Pt as source and drain electrodes. After atmospheric (N2:O2 = 4:1) annealing at 300C for 2 h, 25 nm Al2O3 passivation was deposited through ALD using DMAH at varying temperature from 100C to 300C. The passivated a-IGZO TFTs were finally annealed in O2 at 300C for 2 h. From the transfer curves obtained, decent TFT switching behavior is evident for all a-IGZO TFTs with DMAH-Al2O3 passivation. The summary of electrical characteristics also shows decreasing mobility at higher ALD temperature. This might be attributed to higher hydrogen content at lower temperatures that act as shallow donors and increase the mobility. Moreover, the results of positive bias stress test showed the smallest on-voltage shift of ~ 0.3 V at 200C and 250C. It is speculated that at an optimized ALD condition around 200C and 250C, the deposition temperature is not too low, which might result to incomplete Al2O3 formation, and not too high, which might cause possible degradation of precursor.