# US 2014/0153330 A1 · Method for operating non-volatile memory device and memory controller > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0153330 A1 - Document ID: US20140153330A1 - Status: Published application - Kind: A1 - Application number: 14/088,511 - Filed: 2013-11-25 - Published: 2014-06-05 - Earliest claimed: 2012-12-05 - Assignees: Samsung Electronics Co., Ltd. - Applicants: Samsung Electronics Co., Ltd. - Inventors: HYUN JUN YOON; JAEYONG JEONG; MYUNG-HOON CHOI; KITAE PARK - Web page: https://patentgrep.com/patent/US20140153330A1 ## CPC - G11C 16/26: Sensing or reading circuits; Data output circuits - G11C 11/5642: {Sensing or reading circuits; Data output circuits} - G11C 16/0483: {comprising cells having several storage transistors connected in series} - G11C 16/3404: {Convergence or correction of memory cell threshold voltages; Repair or recovery of overerased or overprogrammed cells} - G11C 16/3422: {Circuits or methods to evaluate read or write disturbance in nonvolatile memory, without steps to mitigate the problem} - G11C: STATIC STORES (semiconductor memory devices H10B) ## Abstract An operating method for a non-volatile memory device includes applying first and second read voltages to a first word line to perform a read operation; counting first memory cells each having a threshold voltage belonging to a first voltage range between the first read voltage and the second read voltage; applying a third read voltage to the first word line sequentially after applying the second read voltage to count second memory cells each having a second threshold voltage belonging to a voltage range between the second read voltage and the third read voltage; comparing the number of first memory cells counted and the number of second memory cells counted; determining a fourth read voltage based on a result of the comparing; and applying the fourth read voltage to the first word line sequentially after applying the third read voltage. ## Claims ### Claim 1 A method of operating a non-volatile memory device, the method comprising: employing a voltage generator to apply first and second read voltages to a first word line of the memory device to perform a read operation; counting first memory cells of the memory device each having a threshold voltage belonging to a first voltage range between the first read voltage and the second read voltage; employing the voltage generator to apply a third read voltage to the first word line sequentially after applying the second read voltage to count second memory cells of the memory device each having a threshold voltage belonging to a second voltage range between the second read voltage and the third read voltage; comparing the number of first memory cells counted and the number of second memory cells counted; determining a fourth read voltage based on a result of the comparing; and employing the voltage generator to apply the fourth read voltage to the first word line sequentially after applying the third read voltage. ### Claim 2 (depends on 1) The operating method of claim 1, wherein when the number of second memory cells is less than the number of first memory cells, the fourth read voltage is determined to be less than the third read voltage. ### Claim 3 (depends on 1) The operating method of claim 1, further comprising: employing the voltage generator to apply a fifth read voltage, less than the fourth read voltage, to the first word line after applying of the fourth read voltage. ### Claim 4 (depends on 3) The operating method of claim 3, further comprising: employing the voltage generator to apply a sixth read voltage, less than the fifth read voltage, to the first word line after applying of the fifth read voltage. ### Claim 5 (depends on 1) The operating method of claim 1, wherein when the number of second memory cells is more than the number of first memory cells, the fourth read voltage is determined to be greater than the third read voltage. ### Claim 6 (depends on 5) The operating method of claim 5, further comprising: employing the voltage generator to apply a fifth read voltage, greater than the fourth read voltage, to the first word line after applying of the fourth read voltage. ### Claim 7 (depends on 6) The operating method of claim 6, further comprising: employing the voltage generator to apply a sixth read voltage, greater than the fifth read voltage, to the first word line after applying of the fifth read voltage. ### Claim 8 (depends on 6) The operating method of claim 6, further comprising: employing the voltage generator to apply a sixth read voltage, greater than the fifth read voltage, to the first word line after applying of the fifth read voltage. ### Claim 9 An method controlling a memory device, the method comprising: counting first memory cells of a memory device each having a threshold voltage belonging to a first voltage range between a first read voltage and a second read voltage; counting second memory cells of the memory device each having a threshold voltage belonging to a second voltage range between the second read voltage and a third read voltage; comparing the number of first memory cells counted and the number of second memory cells counted; and a read voltage level adjusting unit determining, as a result of the comparing, a fourth read voltage to be applied to the memory cells sequentially after the third read voltage. ### Claim 10 (depends on 9) The operating method of claim 9, wherein when the number of second memory cells is less than the number of first memory cells, the fourth read voltage is determined to be less than the third read voltage. ### Claim 11 (depends on 9) The operating method of claim 9, wherein when the fourth read voltage is determined to be less than the third read voltage, a fifth read voltage to be applied sequentially after the fourth read voltage is determined to be less than the fourth read voltage. ### Claim 12 (depends on 9) The operating method of claim 9, wherein when the number of second memory cells is less than the number of first memory cells, the fourth read voltage is determined to be greater than the third read voltage. ### Claim 13 (depends on 12) The operating method of claim 12, wherein if the fourth read voltage is determined to be greater than the third read voltage, a fifth read voltage to be applied sequentially after the fourth read voltage is determined to be greater than the fourth read voltage. ### Claim 14 (depends on 12) The operating method of claim 12, wherein if the fourth read voltage is determined to be greater than the third read voltage, a fifth read voltage to be applied sequentially after the fourth read voltage is determined to be less than the fourth read voltage. ### Claim 15 (depends on 9) The operating method of claim 9, wherein the number of first memory cells is counted by performing a logical operation on a result read using the first read voltage and a result read using the second read voltage. ### Claim 16 A method, comprising: counting first memory cells of a memory device each having a threshold voltage belonging to a first voltage range between a first read voltage and a second read voltage; counting second memory cells of the memory device each having a threshold voltage belonging to a second voltage range between the second read voltage and the third read voltage; comparing the number of first memory cells counted and the number of second memory cells counted to produce a comparison result; and a read voltage level adjusting unit determining, based on the comparison result, a third voltage range for counting memory cells of the memory device having a threshold voltage belonging to the third voltage range. ### Claim 17 (depends on 16) The method of claim 16, wherein when the third read voltage is less than the first read voltage and the number of second memory cells is less than the number of first memory cells, then the third voltage range is determined to span a set of voltages which are less than the second voltage, and when the third read voltage is less than the first read voltage and the number of second memory cells is greater than the number of first memory cells, then the third voltage range is determined to span a set of voltages which are greater than the second voltage. ### Claim 18 (depends on 16) The method of claim 16, wherein when the third read voltage is greater than the first read voltage and the number of second memory cells is less than the number of first memory cells, then the third voltage range is determined to span a set of voltages which are greater than the second voltage, and when the third read voltage is greater than the first read voltage and the number of second memory cells is greater than the number of first memory cells, then the third voltage range is determined to span a set of voltages which are less than the second voltage. ### Claim 19 (depends on 16) The method of claim 16, wherein counting the first memory cells each having a threshold voltage belonging to the first voltage range between the first read voltage and the second read voltage comprises: employing a voltage generator to apply the first read voltage to the memory cells and reading first data values from each memory cell; employing a voltage generator to apply the second read voltage to the memory cells and reading second data values from each memory cell; exclusive OR-ing the first data values and the second data values to produce an output indicating whether each memory cell's threshold voltage is between the first read voltage and the second read voltage. ### Claim 20 (depends on 16) The method of claim 16, further comprising finding a valley in a threshold voltage distribution of the memory cells by iteratively changing voltage ranges and counting numbers of memory cells each having a threshold voltage belonging to each changed voltage range.