Apparatuses and techniques are described for obtaining a threshold voltage distribution for a set of memory cells based on a user read mode. The user read mode can be based on various factors including a coding of a page and an increasing or decreasing order of the read voltages. The read process for the Vth distribution is made to mimic the read mode which is used when the memory device is in the hands of the end user. This results in a Vth distribution which reflects the user's experience to facilitate troubleshooting. In some cases, one or more dummy read operations are performed, where the read result is discarded, prior to a read operation which is used to build the Vth distribution.

A non-volatile memory device, described herein, comprises: a plurality of memory strings and at least one control circuit in communication with the non-volatile memory cell array. The at least one control circuit is configured to perform, for the plurality of memory strings, one erase-verify iteration in an erase operation including determining whether at least one memory string of the plurality of memory strings passes an erase-verify test. The at least one control circuit is configured to, if the at least one memory string passes the erase-verify test, inhibit the at least one memory string for erase including ramping up, to an erase voltage, of a voltage applied to a gate of a SGD transistor of the at least one memory string and to perform a next erase-verify iteration in the erase operation for remaining memory strings of the plurality of memory strings other than the at least one memory string.

A memory device includes a memory block, a peripheral circuit, and a control logic. The memory block includes a plurality of string groups respectively connected to a corresponding select line, among a plurality of select lines. The peripheral circuit performs a program operation of data on the memory block. The control logic controls the program operation of the peripheral circuit. The memory block is connected to first to n-th word lines. The control logic is configured to control the peripheral circuit to perform a first program operation on a physical page, among physical pages that are included in a first string group, connected to an i-th word line, performs a second program operation on a physical page that is connected to an (i−1)-th word line, and perform a dummy program operation on a physical page that is connected to an (i+1)-th word line. Here, n is a natural number equal to or greater than 3, and i is a natural number greater than 0 and less than n−1.

A nonvolatile semiconductor memory device comprises a cell unit including a first and a second selection gate transistor and a memory string provided between the first and second selection gate transistors and composed of a plurality of serially connected electrically erasable programmable memory cells operative to store effective data; and a data write circuit operative to write data into the memory cell, wherein the number of program stages for at least one of memory cells on both ends of the memory string is lower than the number of program stages for other memory cells, and the data write circuit executes the first stage program to the memory cell having the number of program stages lower than the number of program stages for the other memory cells after the first stage program to the other memory cells.

A memory device includes a plurality of memory cells arranged in a plurality of rows and a plurality of strings. A method of programming the memory device includes programming a first row of the memory cells. The method also includes, after programing the first row of the memory cells, programming a second row of the memory cells. The second row is adjacent to the first row in a first string direction. The method further includes, after programming the second row of the memory cells, programming a third row of the memory cells. The third row is two rows apart from the second row in a second string direction opposite to the first string direction.

According to one embodiment, a memory system includes n memory cells, each capable of storing j bits of data; and a controller. The controller is configured to write a first portion of each of first data to n-th data from among nj data with consecutive logical addresses to the n memory cells one by one. The first data has a lowest logical address among the nj pieces of data. The first data to the n-th data have ascending consecutive logical addresses. The controller is configured to write the first portion of one of the first to n-th data as a first bit of the j bits, and write the first portion of another one of the first to n-th data except said one of the first to n-th data as a second bit of the j bits.

In certain aspects, a memory device includes a memory cell array having rows of memory cells, word lines respectively coupled to the rows of memory cells, and a peripheral circuit coupled to the memory cell array through the word lines. Each memory cell is configured to store a piece of N-bits data in one of 2.sup.N levels, where N is an integer greater than 1. The level corresponds to one of 2.sup.N pieces of N-bits data. The peripheral circuit is configured to program, in a first pass, a row of target memory cells, such that each target memory cell is programmed into one of K intermediate levels based on the corresponding piece of N-bits data, wherein 2.sup.N−1<K<2.sup.N. The peripheral circuit is also configured to program, in a second pass after the first pass, the row of target memory cells, such that each target memory cell is programmed into one of the 2.sup.N levels based on the corresponding piece of N-bits data.

An operation method includes buffering data chunks to be programmed in the multi-level cells in a write buffer; backing up at least one backup data chunk of the data chunks to a backup memory; determining a program sequence of the data chunks, the program sequence for programming a non-backup data chunk among the data chunks to the multi-level cells through a second step program operation of the multi-step program operation; and controlling the memory device to program the data chunks in the multi-level cells, based on the program sequence, by performing first and second step program operations of the multi-step program operation in a first page of the multi-level cells, the second step program operation performed in the first page later than another first step program operation performed in a second page subsequent to the first page.

Disclosed in some examples are improvements to data placement architectures in NAND that provide additional data protection through an improved NAND data placement schema that allows for recovery from certain failure scenarios. The present disclosure stripes data diagonally across page lines and planes to enhance the data protection. Parity bits are stored in SLC blocks for extra protection until the block is finished writing and then the parity bits may be deleted.

According to one embodiment, a memory system includes n memory cells, each capable of storing j bits of data; and a controller. The controller is configured to write a first portion of each of first data to n-th data from among n×j data with consecutive logical addresses to the n memory cells one by one. The first data has a lowest logical address among the n×j pieces of data. The first data to the n-th data have ascending consecutive logical addresses. The controller is configured to write the first portion of one of the first to n-th data as a first bit of the j bits, and write the first portion of another one of the first to n-th data except said one of the first to n-th data as a second bit of the j bits.