Transcend 4Gb/CF 133 [7/14] Die stacking and multi level cell multi bit cell flash technologies

COMMITTED T O MEMORY

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Die-Stacking and Multi-Level Cell/Multi-Bit Cell Flash technologies

In order to economically increase the amount of bit-storage that a Flash memory chip can

accommodate, manufacturers often utilize die-stacking and multi-level cell or multi-bit cell

technologies. These technologies result in a Flash memory chip having the capability to

store more data in a single chip.

5.1 DIE-STACKING

Many semiconductor manufacturers use a “die-stacking” technique to double a Flash

memory chip’s capacity. After the semiconductor wafer fabrication process, they cut out the

Flash memory silicon “die” and then attach or stack two separate dies together.

For example, when a semiconductor manufacturer stacks two 1 gigabit dies together, they

form a single 2 gigabit Flash memory chip.

Die -stacking allows for cost-reduced chip alternatives to the larger-capacity, single- die chips

(called “monolithic” chips). Stacking two 8-gigabit chips together, for example, typically

costs far less than buying a low-volume monolithic 16-gigabit chip. The 16-gigabit chip can

then be used to build a 2-GB Flash card (single chip card), or a 4-GB Flash card (two chips

on one card).

Die-stacking is similar to the DRAM chip-stacking technology that Kingston utilizes to

produce high-end server modules. As a result, Kingston’s die-stacked Flash cards are reliable

and deliver high performance.

5.2 MULTILEVEL CELL MLC FLASH TECHNOLOGIES

NAND and NOR Flash memory chips store one (1) bit value (a “0” or a “1”) in each cell. In

multi-level Flash technologies, two (2) or more values are stored into each cell.

Intel Corporation has introduced NOR StrataFlash

™

; AMD has introduced NOR MirrorBit

™

Flash. Other semiconductor manufacturers also manufacture their own multi-level cell

technologies.

NAND MLC Flash technologies were introduced in late 2002, and Kingston has incorporated

MLC Flash memory into its line of standard Flash cards and DataTraveler (DTI/XXX) USB

Flash drives.

5.3 MULTIBIT CELL MBC FLASH TECHNOLOGY

Multi-bit technology is a competing technology to Multi-Level Cell (MLC), and accomplishes

the same goal by storing 2 bits per cell (or 4 values per cell). MBC technology is presently

used in In neon’s TwinFlash

™

memory.

CompactFlash cards

were the  rst small

form factor Flash

memory cards.

5.0