SEMICONDUCTOR MEMORY DEVICE AND METHOD OF OPERATING THE SAME

• US 20180068740A1
• Filed: 06/16/2017
• Published: 03/08/2018
• Est. Priority Date: 09/06/2016
• Status: Active Grant

• Current Assignee: SK Hynix Inc.
• Original Assignee: SK Hynix Inc.
• Inventors: LEE, Hee Youl
• Granted Patent: US 10,109,360 B2
• Time in Patent Office: Days
• CPC Class Codes: G11C 16/14 Circuits for erasing electrically, e.g. erase voltage switching circuits
• CPC Class Codes: G11C 16/26 Sensing or reading circuits; Data output circuits
• CPC Class Codes: G11C 16/3445 Circuits or methods to verify correct erasure of nonvolatile memory cells
• CPC Class Codes: G11C 16/3459 Circuits or methods to verify correct programming of nonvolatile memory cells

Abstract

A semiconductor memory device includes a memory cell array, a read/write circuit and a control logic. The memory cell array includes a plurality of memory cells. The read/write circuit is configured to write data to the memory cell array or read data from the memory cell array. The control logic is configured to control the read/write circuit to perform a read/write operation for the memory cell array. The memory cell array includes a plurality of memory blocks, and each of the memory blocks includes a plurality of sub-blocks. During an operation of erasing a sub-block in a memory block, the control logic selects a sub-block to be erased regardless of a sequence in which the sub-blocks have been programmed, and determines an erase verify voltage based on a position of the selected sub-block.

Claims

1. A semiconductor memory device comprising:

a memory cell array including a plurality of memory cells;

a read/write circuit configured to write data to the memory cell array or read data from the memory cell array; and

a control logic configured to control the read/write circuit to perform a read/write operation for the memory cell array,

wherein the memory cell array includes a plurality of memory blocks, and each of the memory blocks includes a plurality of sub-blocks, and

wherein, during an operation of erasing a sub-block in a memory block, the control logic selects a sub-block to be erased regardless of a sequence in which the sub-blocks have been programmed, and determines an erase verify voltage based on a position of the selected sub-block.

2. The semiconductor memory device according to claim 1,

wherein each of the memory blocks includes two sub-blocks, and

wherein the two sub-blocks include an upper sub-block and a lower sub-block.

3. The semiconductor memory device according to claim 2, wherein the control logic determines the erase verify voltage such that an erase verify voltage for erasing the upper sub-block is greater than an erase verify voltage for erasing the lower sub-block.

4. The semiconductor memory device according to claim 2, wherein, during the operation of erasing the selected sub-block, the control logic determines the erase verify voltage for the operation of erasing the selected sub-block, based on a program state of an unselected sub-block.

5. The semiconductor memory device according to claim 4, wherein the unselected sub-block is adjacent to the selected sub-block.

6. The semiconductor memory device according to claim 2, wherein:

the lower sub-block is erased using a first erase verify voltage if the upper sub-block is in an erased state, and the lower sub-block is erased using a second erase verify voltage if the upper sub-block is in a programmed state, where the first erase verify voltage is different from the second erase verify voltage; and

the upper sub-block is erased using a third erase verify voltage if the lower sub-block is in the erased state, and the upper sub-block is erased using a fourth erase verify voltage if the lower sub-block is in the programmed state, where the third erase verify voltage is different from the fourth erase verify voltage.

7. The semiconductor memory device according to claim 1,

wherein each of the memory blocks includes first to N-th sub-blocks (N is a natural number of 2 or more), and

wherein, during a program operation, the control logic controls the memory cell array and the read/write circuit such that the first sub-block is programmed first, and then the second to N-th sub-blocks are sequentially programmed.

8. The semiconductor memory device according to claim 7, wherein erase verify voltages corresponding to the first to N-th sub-blocks are increased from the first sub-block to the N-th sub-block.

9. The semiconductor memory device according to claim 7,

wherein, during the operation of erasing the selected sub-block, the control logic determines a first erase verify voltage as the erase verify voltage for the operation of erasing the selected sub-block when, among unselected sub-blocks, both sub-blocks adjacent to the selected sub-block are in an erased state,

wherein the control logic determines a second erase verify voltage as the erase verify voltage for the operation of erasing the selected sub-block when both the sub-blocks adjacent to the selected sub-block are in programmed states,

wherein the control logic determines a third erase verify voltage as the erase verify voltage for the operation of erasing the selected sub-block when either one of the sub-blocks adjacent to the selected sub-block is in the erased state and the other sub-block adjacent to the selected sub-block is in a programmed state, and

wherein the first erase verify voltage is greater than the second erase verify voltage, and the second erase verify voltage is greater than the third erase verify voltage.

10. The semiconductor memory device according to claim 7, wherein the sub-blocks have a same size.

11. The semiconductor memory device according to claim 7, wherein the sub-blocks each have a different size.

12. A method for operating a semiconductor memory device including a plurality of memory blocks each of which is divided into a plurality of sub-blocks, the method comprising:

determining a target memory block to be erased;

determining a target sub-block to be erased in the determined memory block;

determining an erase verify voltage of the determined sub-block; and

erasing the determined sub-block using the determined erase verify voltage.

13. The method according to claim 12, wherein the determining of the target sub-block to be erased comprises selecting the sub-block to be erased, regardless of a sequence in which the sub-blocks have been programmed in the target memory block to be erased.

14. The method according to claim 12,

wherein each of the plurality of memory blocks includes an upper sub-block and a lower sub-block, and

wherein the determining of the erase verify voltage comprises determining the erase verify voltage such that an erase verify voltage for erasing the upper sub-block is greater than an erase verify voltage for erasing the lower sub-block.

15. The method according to claim 12,

wherein each of the plurality of memory blocks includes an upper sub-block and a lower sub-block, and

wherein the determining of the erase verify voltage comprises determining the erase verify voltage for an operation of erasing the determined sub-block, based on a program state of an unselected sub-block.

16. The method according to claim 15, further comprising:

determining a first erase verify voltage as the determined erase verify voltage for erasing the target sub-block when, among unselected sub-blocks, both unselected sub-blocks adjacent to the target sub-block are in an erased state;

determining a second erase verify voltage as the determined erase verify voltage for erasing the target sub-block when both unselected sub-blocks adjacent to the target sub-block are in programmed states; and

determining a third erase verify voltage as the determined erase verify voltage for erasing the target sub-block when either one of the unselected sub-blocks adjacent to the target sub-block is in the erased state and the other sub-block adjacent to the target sub-block is in the programmed state.

17. The method according to claim 16, wherein the first erase verify voltage is greater than the second erase verify voltage, and the second erase verify voltage is greater than the third erase verify voltage.