A novel double-density, single-gate vertical channel (SGVC) 3D NAND Flash that is tolerant to deep vertical etching CD variation and possesses robust read-disturb immunity

We demonstrate a novel vertical channel 3D NAND Flash architecture - SGVC. SGVC device is a single-gate, flat-channel TFT charge-trapping device with ultra-thin body. Our novel array decoding method enables a tight-pitch (25nm HP) metal BL design to fulfill the large page size (16KB for one plane) for high-performance NAND product. The SGVC flat cell possesses excellent P/E window of ~10V, small X/Y/Z adjacent-cell interferences, good self-boosting inhibit, and >10K P/E cycling endurance. Due to the advantage of flat cell that is insensitive to etching CD, SGVC device is tolerant to the non-ideal vertical etching and has shown excellent device uniformity from layer to layer. In sharp contract to GAA VC, SGVC suffers no penalty from field-enhancement effect, thus has shown very robust read-disturb immunity against long-term gate stressing. Due to (1) two physical bits per X-Y cell footprint, and (2) efficient array design with minimal overhead, SGVC architecture has 2 to 4 times memory density than GAA VC 3D NAND at the same stacking layer number.