부산대학교 도서관

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 ( $V_{\mathrm {th}}$ ) setting method that all the SSTs on each layer are set to targeted the $V_{\mathrm {th}}$ 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 $V_{\mathrm {th}}$ values of SSTs are set to the targeted $V_{\mathrm {th}}$ values by the new method. Moreover, memory operations are examined in the fabricated structure after setting the $V_{\mathrm {th}}$ values of all the SSTs by the new method. As a result, stable memory operations are obtained successfully without the interference between stacked layers.