Self-diagnostic smart verify algorithm in user mode to prevent unreliable acquired smart verify program voltage

Abstract

A memory apparatus and operating method are provided. The apparatus includes memory cells connected to word lines and disposed in memory holes and configured to retain a threshold voltage. The memory holes are organized in rows grouped in strings. A control means is coupled to the word lines and the memory holes and programs the memory cells associated with a first one of the strings in a program operation and acquire a smart verify programming voltage in a smart verify operation including smart verify loops. The control means discards the smart verify programming voltage and determines another smart verify programming voltage in another smart verify operation on the memory cells associated with a second one of the strings in response to a quantity of the smart verify loops needed to complete programming of the memory cells associated with the first one of the strings being outside a predetermined threshold criteria.