Sandisk Technologies Inc.

Yew Yin Ng

Mrinal Kochar

Aaron Lee

Dennis S Ea

Mikhail Palityka

Abhijeet Bhalerao

Ivan Baran

Deepanshu Dutta

Gautam Ashok Dusija

Niles Yang

Data that is initially stored in Single Level Cell (SLC) blocks is subsequently copied (folded) to a Multi Level Cell (MLC) block where the data is stored in MLC format, the data copied in a minimum unit of a fold-set, the MLC block including a plurality of separately-selectable sets of NAND strings, data of an individual fold-set copied exclusively to two or more word lines of an individual separately-selectable set of NAND strings in the MLC block.

Data folding in 3D nonvolatile memory

Partially-bad blocks are identified in a 3-D block-erasable nonvolatile memory, each partially-bad block having one or more inoperable separately-selectable sets of NAND strings and one or more operable separately-selectable sets of NAND strings. Operable sets of NAND strings within two or more partially-bad blocks are identified and are mapped to form one or more virtual blocks that are individually assigned virtual block addresses. The virtual block address are maintained in a list and used to access the virtual blocks.

Partially-bad block operation in 3-D nonvolatile memory

Non-volatile memory systems with multi-write direction memory units are disclosed. In one implementation an apparatus comprises a non-volatile memory and a controller in communication with the non-volatile memory. The controller is configured to select an empty memory block of the non-volatile memory for the storage of data; examine an identifier associated with the memory block to determine a write direction for the storage of data; and write data to the memory block beginning with an initial word line of the memory block or a last word line of the memory block dependent on the write direction. The controller is further configured to erase the memory unit and, in response to erasing the memory unit, modify the identifier to change the write direction for a subsequent write of data to the memory block.

Non-volatile memory systems with multi-write direction memory units

Apparatus and method for performing a post-write read in a memory device are disclosed. A memory device may include 3-dimensional memory, with the wordlines in a memory block each having multiple strings. Periodically, the memory device may analyze the wordlines for defects by performing a post-write read on a respective wordline and analyzing the read data to determine whether the respective wordline is defective. Rather than reading all of the strings for the respective wordline, less than all of the strings (such as only one of the strings) for the respective wordline are read. In this way, determining whether the respective wordline in 3-dimensional memory may be performed more quickly.

Enhanced post-write read for 3-D memory

A method of searching for a boundary between a written portion and an unwritten portion of an open block may include performing a word line by word line binary search of a first physical area of the open block to identify a last written word line of the first physical area of the block, and subsequently, searching in at least a second physical area of the open block based on the last written word line of the first physical area of the block as identified by the binary search.

Efficient scanning of nonvolatile memory blocks

In a nonvolatile memory array that has a binary cache formed of SLC blocks and a main memory formed of MLC blocks, corrupted data along an MLC word line is corrected and relocated, along with any other data along the MLC word line, to binary cache, before it becomes uncorrectable. Subsequent reads of the relocated data directed to binary cache.

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Milpitas, CA, United States of America

Yew Yin Ng