Sandisk Technologies Inc.

Western Digital Technologies, Inc.

Abhijith Prakash

Xiang Yang

Anubhav Khandelwal

Jiahui Yuan

Deepanshu Dutta

Huai-Yuan Tseng

Dengtao Zhao

Yu-Chung Lien

Wei Zhao

Jiacen Guo

Shubhajit Mukherjee

Masaaki Higashitani

Henry Chin

Shinsuke Yada

Muhammad Masuduzzaman

Parth Amin

Anirudh Amarnath

Kazuki Isozumi

Keyur Payak

Dong-Il Moon

Vishwanath Basavaegowda Shanthakumar

Aravind Suresh

A memory apparatus and method of operation are provided. The apparatus includes source-side and drain-side select gate transistors for coupling respectively to the source-side and drain-side of memory holes of memory cells. During the read operation, the control means ramps the word lines to a read pass voltage. The control means is configured to delay ramping the voltage applied to the source-side select gate transistors to a select gate voltage until a predetermined time after the selected ones of the word lines and the unselected ones of the word lines ramp to the read pass voltage. The control means is also configured to delay ramping the voltage applied to the drain-side select gate transistors to a select gate voltage until a different predetermined time after the selected ones of the word lines and the unselected ones of the word lines ramp to the read pass voltage.

Delayed select gate ramp-up for peak read current consumption reduction for non-volatile memory apparatus

Technology is disclosed herein for detecting evolved bad blocks in three-dimensional NAND. The test may include a drain side erase that includes applying an erase voltage from the bit lines and a source side erase that includes applying an erase voltage from the source line(s). If the source side erase performed worse than the drain side erase this may indicate a defect near the source side of the block. For example, the source side erase may fail but the drain side erase may pass. As another example the source side erase may take at least a pre-determined number of additional erase pulses to pass than the drain side erase. If the block is found as having a defect the entire block could be marked bad or the defective region could be identified such that the defective region is no longer used.

Evolving bad block detection in non-volatile memory

Memory die management based on biasing voltages. Some memory dies are formed of memory holes having a semi-circular shape. This semi-circular shape results in a decrease in biasing voltage compared to memory holes having a circular shape. Systems and methods described herein organize memory dies into memory die groups according to their biasing voltages. During operation, data is relocated between the memory die groups based on how often the data is read. Data may be scrambled within their respective memory die groups to maintain appropriate storage space.

Memory die management

The memory device includes a memory block with an array of memory cells arranged word lines. The memory device also includes control circuitry that is configured to program final data into a selected word line in a multi-pass programming operation that includes a first pass and a second pass. In the first pass, the control circuitry is configured to program the memory cells of the selected word line to foggy data and program parity data in the memory device. The parity data includes three possible data states. Prior to the second pass, the control circuitry is configured to read the foggy data and the parity data and reconstruct the final data from the foggy data and the parity data. In the second pass, the control circuitry is configured to program the memory cells of the selected word line from the foggy data to the final data.

Multi-stage programming techniques with three states per memory cell parity

A memory device includes a memory block including a plurality of sub-blocks each including a plurality of memory cells and control circuitry configured to perform single-side erase operations on the memory block in a sub-block mode in which a selected sub-block of the plurality of sub-blocks in the memory block is erased while unselected sub-blocks of the plurality of sub-blocks in the memory block are not erased and selectively perform data scrubbing and relocation operations on the plurality of sub-blocks of the memory block. To perform a data scrubbing and relocation operation, the control circuitry is configured to determine whether to perform the data scrubbing and relocation operation on a first sub-block based on a position of the first sub-block relative to an erase side of the memory block and selectively perform the data scrubbing and relocation operation on the first sub-block in response to the determination.

Single block mode block handling for single-side GIDL erase

The memory device includes a memory block with memory cells arranged in word lines and control circuitry that is configured to program the memory cells in a selected word line to respective programmed data states in program loops, which each include verify operations. The control circuitry is further configured to lock out any of the memory cells in the selected word line memory cell from subsequent program pulses and verify operations in response to that memory cell passing verify for its respective programmed data state. For a selected programmed data state, the control circuitry is further configured to re-verify all of the memory cells in the selected word line that are being programmed to the selected programmed data state and release all memory cells that were locked out but fail re-verify in order to allow any memory cells that mistakenly passed verify to be programmed further.

Intermediate re-verify for achieving tighter threshold voltage distributions in a memory device

A storage device is provided that conditionally performs read refresh in blocks having higher P/E cycles or older programming times, while refraining from performing read refreshes in blocks having lower P/E cycles or recent programming times. The storage device includes a memory and a controller. The memory includes a block having cells. The controller performs a read refresh on the cells when a number of P/E cycles of the block exceeds an age threshold or after a threshold amount time has elapsed since data was programmed in the block. The controller may also refrain from performing read refreshes on the cells until the number of P/E cycles exceeds the age threshold or until a threshold amount of time has elapsed since the data is programmed. As a result, lower BER may occur due to wider Vt margins, while power and system overhead may be saved.

Data retention-specific refresh read

Systems and methods for bit line modulation to compensate for cell source variation are disclosed. For example, a method for reading data from non-volatile storage comprising determining a first bit line level based on a first programmed data state that is being sensed and determining a second bit line level based on a second programmed data state that is being sensed. As another example, a storage device comprising a first bit line driver configured to generate a first bit line level for a first set of bit lines corresponding to a first set of memory strings based on a first cell source level associated with the first set of memory strings a second bit line driver configured to generate a second bit line level for a second set of bit lines corresponding to a second set of memory strings based on a second cell source level associated with the second set of memory strings.

Bit line modulation to compensate for cell source variation

A non-volatile memory system comprises a plurality of non-volatile memory cells divided into three or more tiers. The memory cells can be programmed, erased and read. In order to achieve uniform erase speed for the three or more tiers, the erase process comprises applying a larger voltage bias to control gates of non-volatile memory cells in the outer tiers than the voltage bias applied to control gates of non-volatile memory cells in one or more inner tiers.

Erase method for non-volatile memory with multiple tiers

The nonvolatile memory includes a plurality of nonvolatile memory cells configured to store multiple data states; a word line connected to a control gate of at least one of the plurality of non-volatile memory cells; a control gate line to supply a control gate signal; a word line switch connected between the word line and the control gate line to control the potential applied to the word line from the control gate line; and a memory controller circuit. The memory controller circuit is configured to control a word line potential on the word line and a control gate potential on the control gate line and to control a state of the control gate. The memory controller circuit, when the nonvolatile memory transitions to a not-on state, is further configured to turn off the word line switch and to charge the control gate line to a charged potential.

Control gate signal for data retention in nonvolatile memory

A memory apparatus and method of operation are provided. The apparatus includes memory cells connected to word lines including a dummy word line and other data word lines. The memory cells are disposed in memory holes and configured to retain a threshold voltage. A control means is coupled to the word lines and the memory holes and is configured to determine whether one of the word lines being programmed in a program operation is a particular one of the word lines adjacent the dummy word line needing a dummy positioning operation. The control means is also configured to program the memory cells connected to the dummy word line to adjust the threshold voltage to a predetermined position threshold voltage in the dummy positioning operation in response to determining the one of the plurality of word lines being programmed in the program operation is the particular one of the word lines.

Pre-position dummy word line to facilitate write erase capability of memory apparatus

A memory apparatus and method of operation are provided. The apparatus includes memory cells connected to word lines and disposed in memory holes organized in rows grouped in strings and configured to retain a threshold voltage. The memory cells are connected in series between a drain-side select gate transistor on a drain-side of each of the memory holes and a source-side select gate transistor on a source-side of each of the memory holes. A control means determines whether a downshift recovery trigger event has occurred in memory operations. In response to determining the downshift recovery trigger event has occurred, the control means inserts at least one of a predetermined idle time in the memory operations and a recovery pulse of a negative voltage to the drain-side select gate transistor of the memory holes of the strings for a predetermined pulse period of time during one of the memory operations.

Recovery pulses to counter cumulative read disturb

A memory apparatus and method of operation are provided. The apparatus includes memory cells each connected to word lines. The memory cells are disposed in strings and configured to retain a threshold voltage corresponding to data states. A control means is configured to apply verification pulses of program verify voltages each associated with one of the data states to selected ones of the word lines to determine whether the memory cells connected thereto have the threshold voltage above each of the program verify voltages targeted for each of the memory cells during a program-verify portion of a program operation. The control means is also configured to trim the program verify voltages for each of the data states for a grouping of the memory cells based on quantities of the memory cells having the threshold voltage crossing over between the data states in crossovers in a verify level trimming process.

Refresh frequency-dependent system-level trimming of verify level offsets for non-volatile memory

A memory apparatus and method of operation are provided. The apparatus includes memory cells connected to word lines including at least one edge word line and other data word lines. The memory cells are arranged in strings and are configured to retain a threshold voltage corresponding to data states. The strings are organized in rows and a control means is coupled to the word lines and the strings and identifies the at least one edge word line. The control means programs the memory cells of the strings in particular ones of the rows and associated with the at least one edge word line to have an altered distribution of the threshold voltage for one or more of the data states compared to the memory cells of the strings not in particular ones of the rows and not associated with the at least one edge word line during a program operation.

Edge word line data retention improvement for memory apparatus with on-pitch semi-circle drain side select gate technology

A plurality of memory programming the memory cells to at least one programmed data state in a plurality of program-verify iterations. In each iteration, after a programming pulse, a sensing operation is conducted to compare the threshold voltages of the memory cells to a low verify voltage associated with a first programmed data state and to a high very voltage associated with the first programmed data state. The sensing operation includes discharging a sense node through a bit line coupled to one of the memory cells and monitoring a discharge time of the sense node. At least one aspect of the sensing operation is temperature dependent so that a voltage gap between the high and low verify voltages is generally constant across a range of temperatures.

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Milpitas, CA, United States of America

Abhijith Prakash