Tailoring the number of lines for IGO-channel 2T0C DRAM comparable to conventional 2-line operation 1T1C structure for highly scaled cell volume

  • Capacitor-less 2T0C dynamic random-access memory (DRAM) employing oxide semiconductors (OSs) as a channel has great potential in the development of highly scaled three dimensional (3D)-structured devices. However, the use of OS and such device structures presents certain challenges, including the trade-off relationship between the field-effect mobility and stability of OSs. Conventional 4-line-based operation of the 2T0C enlarges the entire cell volume and complicates the peripheral circuit. Herein, we proposed an IGO (In-Ga-O) channel 2-line-based 2T0C cell design and operating sequences comparable to those of the conventional Si-channel 1 T1C DRAM. IGO was adopted to achieve high thermal stability above 800 ℃, and the process conditions were optimized to simultaneously obtain a high µFE of 90.7 cm2·V-1·s-1, positive Vth of 0.34 V, superior reliability, and uniformity. The proposed 2-line-based 2T0C DRAM cell successfully exhibited multi-bit operation, with the stored voltage varying from 0 V to 1 V at 0.1 V intervals. Furthermore, for stored voltage intervals of 0.1 V and 0.5 V, the refresh time was 10 s and 1 000 s in multi-bit operation; these values were more than 150 and 15 000 times longer than those of the conventional Si channel 1T1C DRAM, respectively. A monolithic stacked 2-line-based 2T0C DRAM was fabricated, and a multi-bit operation was confirmed.
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Kwag J H, Choi S H, Kim D, Lee J Y, Hwang T, Oh H J, Park C K, Park J S. 2025. Tailoring the number of lines for IGO-channel 2T0C DRAM comparable to conventional 2-line operation 1T1C structure for highly scaled cell volume. Int. J. Extrem. Manuf. 7 055503.. DOI: 10.1088/2631-7990/add7a3
Kwag J H, Choi S H, Kim D, Lee J Y, Hwang T, Oh H J, Park C K, Park J S. 2025. Tailoring the number of lines for IGO-channel 2T0C DRAM comparable to conventional 2-line operation 1T1C structure for highly scaled cell volume. Int. J. Extrem. Manuf. 7 055503.. DOI: 10.1088/2631-7990/add7a3

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