Sandisk Technologies Inc.

Dong-Il Moon

Henry Chin

Erika Penzo

Jiahui Yuan

Wei Zhao

Abhijith Prakash

Abu Naser Zainuddin

Jie Liu

A memory apparatus and method of operation are provided. The apparatus includes memory cells connected to word lines and disposed in memory holes each comprising a channel. The memory cells retain a threshold voltage and are operable in one of a first read condition in which a word line voltage of the word lines is discharged and a second read condition in which the word line voltage of the word lines is coupled up to a residual voltage level. A control means is configured to apply a predetermined refresh read voltage to the word lines at predetermined intervals of time during a refresh read operation to maintain the memory cells in the second read condition. The control means also adjusts a read setup time in which the word lines are ramped up and the channel is discharged during a read operation based on occurrences of the refresh read operation.

Word line-dependent word line and channel read setup time in first read state of non-volatile memory

To reduce spikes in the current used by a NAND memory die, different ramp rates are used for the pass voltage applied to unselected word lines during a program operation depending on whether data is stored in a multi-level cell (MLC) format or in a single level cell (SLC) format. These ramp rates can be determined through device characterization and stored as parameter values on the memory die. Different ramp rate interval values can also be used for the pass voltage applied to unselected word lines during a program operation depending on whether data is stored in an MLC format or in an SLC format.

NAND memory with different pass voltage ramp rates for binary and multi-state memory

A memory apparatus and method of operation are provided. The apparatus includes memory cells each connected to one of a plurality of word lines. The memory cells are disposed in strings and configured to retain a threshold voltage corresponding to one of a plurality of data states. A control means is coupled to the plurality of word lines and the strings and is configured to apply a read voltage to a selected ones of the plurality of word lines during a read operation and ramp down to a discharge voltage at an end of the read operation and apply a ready voltage to the selected ones of the plurality of word lines during a ready period of time following the read operation. The control means is also configured to adjust at least one of the discharge voltage and the ready voltage based on a temperature of the memory apparatus.

Temperature-dependent word line voltage and discharge rate for refresh read of non-volatile memory

An apparatus disclosed herein comprises: a plurality of memory cells and a control circuit coupled to the plurality of memory cells. The control circuit is configured to: acquire a first set of read levels on a wordline of a first block of pages of memory cells; acquire a second set of read levels on a first wordline of a second block of pages of a second set of memory cells in response to determining that the fail bit count of the page after a read operation is above the threshold amount; and acquire a third set of read levels on a second wordline of the second block in response to determining that the fail bit count of the page after the second read operation is above the threshold amount.

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San Jose, CA, United States of America

Dong-Il Moon