下一代存储材料

Core Insights - Oxide semiconductors are gaining attention as potential materials for next-generation storage architectures due to their compatibility with back-end-of-line (BEOL) processes and their ability to enhance key performance metrics such as durability, data retention, and scalability [1][2][26] Group 1: Advances in Oxide Semiconductor Technology - Significant progress has been made in n-type oxide semiconductors, including IGZO, InWO, InSnO, and InO, which are suitable for BEOL storage unit access transistors due to their ultra-low leakage characteristics and compatibility with low thermal budget processes below 400°C [3][19] - The article summarizes three main types of BEOL-compatible oxide semiconductor-based memory: DRAM-like 1T-1C structures, capacitorless gain cell memory, and ferroelectric memory [3][19] Group 2: Performance of 1T-1C Storage Chips - A recent demonstration of a 1T-1C storage chip using n-type oxide semiconductor transistors showed excellent performance with a random cycle time of 8 ns and a retention time of 128 ms at a VDD of 0.75 V, indicating high reliability [4][16] - The storage unit array is integrated in a cell-over-peripheral (COP) structure, which minimizes signal propagation distance, providing significant advantages in density expansion, delay, and power consumption [4][16] Group 3: Challenges in Device Optimization - Key challenges remain in optimizing performance for n-type oxide semiconductor devices, including contact resistance (RC) optimization to achieve high drive current (ION) in short-channel devices, threshold voltage (VT) tuning to suppress leakage, and process control to enhance reliability [6][10][12] - The presence of hydrogen in n-type oxide systems is highly sensitive to reliability performance, necessitating surface treatment and passivation methods to minimize hydrogen content and prevent diffusion into the channel [12][14] Group 4: Development of p-Type Oxide Semiconductors - Research on p-type oxide semiconductors, particularly SnO, is ongoing, with challenges including improving mobility, reducing contact resistance, and achieving stable threshold voltage [19][20] - Recent advancements in the fabrication of SnO devices using wafer-compatible processes have shown promising results, with an ION/IOFF ratio of approximately 10⁴ and a mobility of about 1 cm²/V·s [20][22] Group 5: Ferroelectric Field-Effect Transistors (FeFETs) - FeFETs using Hf₁₋ₓZrₓO as the ferroelectric layer are considered promising candidates for high-speed, low-power storage, but integrating ferroelectric materials with oxide semiconductor channels presents unique challenges [24][25] - A breakthrough in highly scaled OS-FeFET devices demonstrated a unit area of 0.009 μm², achieving a conduction current of 40 μA/μm and over 1000 s of data retention at 85°C [25]