Sandisk Technologies Inc.

Zac Shepard

Steven Theodore Sprouse

Chris Nga Yee Avila

Brian Murphy

Qing Li

Xiaoyu Yang

Neil David Hutchison

Albert T Meeks

Raz Dan

Kim Le

Enosh Levi

In a nonvolatile memory that stores data in two or more different data storage formats, such as binary and MLC, a separation scheme is used to distribute blocks containing data in one data storage format (e.g. binary) so that they are separated by at least some minimum number of blocks using another data storage format (e.g. MLC).

Data retention in nonvolatile memory with multiple data storage formats

In a nonvolatile memory array, blocks that contain only obsolete data are modified by adding charge to their cells, increasing the charge level from the programmed charge levels that represented obsolete data to elevated charge levels. The increase in overall charge in such blocks lessens the tendency of such blocks to impact data retention in neighboring blocks.

Obsolete block management for data retention in nonvolatile memory

A non-volatile memory chip package is prepared for surface mounting to a substrate in a solder reflow process by programming erased blocks to higher threshold voltage levels, to improve data retention for blocks which are preloaded with content, such as by an electronic device manufacturer. Following the surface mounting, the previously-erased blocks are returned to the erased state. The threshold voltage of storage elements of the preloaded blocks can change during the surface mounting process due to a global charge effect phenomenon. The effect is most prominent for higher state storage elements which are surrounded by erased blocks, in a chip for which the wafer backside was thinned and polished. The erased blocks can be programmed using a single program pulse without performing a verify operation, as a wide threshold voltage distribution is acceptable.

Maintaining integrity of preloaded content in non-volatile memory during surface mounting

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Zac Shepard