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

Abstract

The extraction of nitride trap density (Nt) 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 Nt at EC-ET value of 1.20 eV using the IP pattern was as low as 1.01×10 19 cm -3 eV -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. INDEX TERMS 3D NAND flash memory, data retention, lateral migration, trap profilingThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.

Effects of Poly-Si Grain Boundary on Retention Characteristics under Cross-Temperature Conditions in 3-D NAND Flash Memory

“…Hurkx band-to-band tunneling model for gate induced drain leakage (GIDL) erase, and the Shockley-Read-Hall (SRH) model for capture or emission of carriers into traps were adopted. Transient simulation with the non-local tunneling model was applied for program and erase operations [29]. Figure 5a shows the channel electron density near the BE-TOX interface along the BL direction for the neutral and programmed target cells at the subthreshold region.…”

Advanced FTIR optical modeling for hydrogen content measurements in 3D NAND cell nitride and amorphous carbon hard mask

“…7,8 These effects bring about more process challenges as the 3D NAND scaling continues, because of their impact on the program/erase times, 9 charge retention capabilities, 10 and threshold voltage. 11 Since the trap centers in SiN are mainly H-and O-incorporated defects at the nitrogen vacancy and substitute defects, 6,10,12 it is important to measure the hydrogen content which can influence the trapping energy levels and location. 13 Previously, the hydrogen content for SiO 2 /SiN tier stacks were measured by FTIR for process control of dry etch selective ratios, 14 but there have been few reports for cell nitride owing to the thinness (typically a few nm).…”