A 29-Gb/mm2 1-Tb 3-b/Cell 3-D Flash Memory With CMOS Direct Bonded Array (CBA) Technology

This article reports a 1-Tb 3-b/cell 3-D flash memory fabricated with CMOS direct bonded array (CBA) technology. Compaction of circuits and wires achieves the highest bit density in the world over 29 Gb/mm² with 332-word line (WL) layers. The bit density is improved by 71% from a previous generation despite the number of WL layers being increased only by 52%. This design also achieves a 29% read energy efficiency improvement and features a 4.8-Gb/s I/O interface using power-isolated low-tapped termination (PI-LTT). The energy efficiency improvement plays a vital role in suppressing rapidly escalating energy densities potentially caused by the compaction and the improved I/O rate.