Dong Hyuk Chae

The Compact Modeling of Channel Potential in Sub-30-nm NAND Flash Cell String

This letter presents a compact model of nand Flash strings in which complex characteristics of scaled-down Flash cells can be captured very accurately through simple circuit simulation. Different from previous modeling studies, the proposed model has detailed physical descriptions for channel potential of Flash cell so that various program disturbances due to leakages in nand string can be easily analyzed. The compact model of channel potential is fully compatible with BSIM4 SPICE model. By applying compact model to the 30-nm nand product, many phenomena in the device were realized with more than 95% accuracy at the expense of only a few minutes.

A Compact Model for Channel Coupling in Sub-30 nm NAND Flash Memory Device

This paper presents an analytic model for NAND flash array where channel coupling embodies. Channel coupling effect which is becoming a more serious issue in developing high-density flash memory devices should be effectively suppressed. By applying the coupling model to a 30-nm NAND flash product, the simulation showed a good agreement with the measurement results. Also, complex problems in scaled NAND flash memories could be accurately explained by circuit simulations. This evaluation will be useful in developing high-density multi-level cell (MLC) NAND flash technologies.

16-Gigabit, 8-level NAND flash memory with 51nm 44-cell string technology

Eight-level NAND flash memories with 51 nm design rule and 44-cell string floating gate technology have been successfully developed for the first time. 44-cell string with floating poly silicon and tungsten silicide (WSi) gate structure reduced the cell area per bit and improved chip cost efficiency. 44-cell string structure shows acceptable cell current and the results of endurance and interference are quite comparable to the conventional 32-cell string structure.