Thus, after repeatedly program/ erase ( P/ E) cycling, residual charge buildup occurs, which aggregate the second bit effect and leads to the serious degradation of cycling endurance and retention. 经过多次编程/擦除循环后,残余电荷逐渐堆积,加重了单元的第二位比特效应,同时使单元耐受力和保持性能发生严重的退化。