사업성과

학술대회

학술대회

Fabrication of IGZO Thin Film Transistor Using Dry Etching Method with High Mobility and Stability
Author
Jeong-Min Park, Jang-Yeon Kwon
Conference
ITC 2024

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As the DRAM market grows, the demand for component miniaturization intensifies. However, ongoing miniaturization encounters scaling limitations due to increasing off-current. DRAM's 1T-1C cell structure faces challenges such as shortened capacitor charge retention (< 64 ms), necessitating frequent refresh cycles for data maintenance. To overcome these obstacles, IGZO with low leakage current property [1], which has been only utilized for display TFT, has been adopted as a new channel material in transistor for DRAM.

In this study, In-Ga-Zn-O (IGZO) based thin-film transistors (TFTs) were successfully fabricated using photolithography and a dry etching method with chlorine-based gas. To achieve precision in the fabrication of sub-micro-level TFTs, the angle of the channel layer etching played a crucial role, measured at a near-perpendicular 81.843°. Our a-IGZO TFT achieved a high mobility of 32.11 cm2/Vs, a reliability of 0.41 V under 15 V of gate stress for an hour, a threshold voltage of 2.46 V, a subthreshold gate swing value of 0.33 V/decade and an on/off ratio exceeding 1.02*108 through appropriate annealing treatment, shown in Fig. 1., addressing industrial goals in reliability and performance. The improved characteristics of the a-IGZO TFT, based on dry-etched channels, enhance the potential for solving the existing refresh rate problem in Si transistor-based DRAM as device scaling continues, leveraging the low leakage current advantages of IGZO.