Multi-Level Threshold Voltage Setting Method of String Select Transistors for Layer Selection in Channel Stacked NAND Flash Memory

作者：Kwon Dae Woong^*; Kim Wandong; Kim Do Bin; Lee Sang Ho; Seo Joo Yun; Baek Myung Hyun; Park Ji Ho; Choi Eunseok; Cho Gyu Seong; Park Sung Kye; Park Byung Gook

来源：IEEE Electron Device Letters, 2015, 36(12): 1318-1320.

DOI：10.1109/LED.2015.2491367

• 3D NAND flash memory
• channel stacked NAND flash memory
• stacked layer selection
• LSM
• SST threshold voltage setting

In this letter, we propose a simplified channel-stacked array with a layer selection by multi-level operation (SLSM) and a new string select transistors (SSTs) threshold voltage (V-th) setting method that all the SSTs on each layer are set to targeted the V-th values simultaneously by one erase operation. To verify the validity of the new method in SLSM, TCAD simulations are performed, and a fabricated pseudo SLSM is measured. It is verified that the V-th values of SSTs are set to the targeted V-th values by the new method. Moreover, memory operations are examined in the fabricated structure after setting the V-th values of all the SSTs by the new method. As a result, stable memory operations are obtained successfully without the interference between stacked layers.

• 出版日期2015-12