Highlight
- In this work, we proposed a concept of CAA 3D 2T0C-FeDRAM using AOS and ALD-deposited HZO ferroelectrics with stable ferroelectric properties and excellent performance.
- The optimized hetero a-ITZO/a-IGZO structure marks a pivotal advancement in achieving superior stress stability, and the double gate a-ITZO/a-IGZO FeFET showed an enlarged MW of 1.5 V and reliable multi-level states.
- We achieved a record-long multibit retention time of over 2000 s and 4-bit storage, highlighting the potential for low-power, high-density 3D DRAM applications.
Press release
- 뉴시스, “한양대 ERICA 김영현 교수팀, 차세대 D램 기술 개발”
- 신아일보, “한양대 ERICA 김영현 교수팀, 차세대 D램 기술 개발”
- NEWSH, “한양대 ERICA 김영현 교수팀, 초장보유시간 및 다중레벨셀 구현 가능한 차세대 D램 기술 개발”
- 매일일보, “김영현 한양대 ERICA 교수팀, 차세대 D램 기술 개발”
- 뉴데일리경제, “한양대 ERICA 김영현 교수팀, 초장보유시간·다중레벨셀 구현 가능한 차세대 D램 기술 개발”
Schematic image of 2T0C-FeDRAM with a record-long multibit retention time
Abstract
Conventional DRAM, consisting of one transistor and one capacitor (1T1C), requires periodic data refresh processes due to its limited retention time and data-destructive read operation. Here, we propose and demonstrate a novel 3D-DRAM memory scheme available with a single transistor and a single ferroelectric field-effect transistor (FeFET) DRAM (2T0C-FeDRAM), which offers extended retention time and non-destructive read operation. This architecture uses a back-end-of-line (BEOL)-compatible amorphous oxide semiconductor (AOS) that is suitable for increasing DRAM cell density. Notably, the device structures of a double gate a-ITZO/a-IGZO FeFET, used for data storage and reading, are engineered to achieve an enlarged memory window (MW) of 1.5 V and a prolonged retention time of 104 s. This is accomplished by a double gate and an a-ITZO/a-IGZO heterostructure channel to enable efficient polarization control in hafnium-zirconium oxide (HZO) layers. We present successful program/erase operations of the double gate a-ITZO/a-IGZO FeFET through incremental step pulse programming (ISPP), demonstrating multi-level states with remarkable retention characteristics. Most importantly, we perform 2T0C-FeDRAM operations by electrically connecting the double gate a-ITZO/a-IGZO FeFET and the a-ITZO FET. Leveraging the impressive performance of the double gate a-ITZO/a-IGZO FeFET technology, we have effectively showcased an exceptionally record-long retention time exceeding 2000 s and 4-bit multi-level states, positioning it as a robust contender among emerging memory solutions in the era of artificial intelligence.
Congratulations, Tae hyeon and Simin!