Extraction of Nitride Trap Profile in 3-D NAND Flash Memory Using Intercell Program Pattern

Abstract

The extraction of nitride trap density ( $N_{t}$ ) filled with electrons emitted by thermal emission (TE) in the charge-trapping layer of 3-D NAND flash memory is demonstrated. The intercell program (IP) pattern was adopted to intentionally inject electrons into the intercell region to minimize the influence of lateral migration (LM) on the trap profiles. This was confirmed by the retention characteristics observed at 120 °C, where the charge loss is mainly caused by the TE of the trapped electrons in the nitride layer. The extracted peak value of $N_{t}$ at $E_{C}$ - $E_{T}$ value of 1.20 eV using the IP pattern was as low as $1.01\times 10^{19}$ cm−3eV−1, in the scan range of 0.96 eV to 1.27 eV. This value was 17% lower than that from the conventional adjacent cell program (P-P-P) pattern. Therefore, the IP pattern can be used in extracting trap profiles in the SiN layer in scaled 3-D NAND memories.

Keywords

• 3D NAND flash memory
• data retention
• lateral migration
• trap profiling