Like urban planners trying to squeeze more residents onto a city block, chip makers are talking about ways to improve their products by building upward rather than squeezing circuitry closer together. IBM and Micron plan to work together to commercialize the concept.

The fundamental idea is to stack chips on top of each other, using more and faster data pathways than typically connect semiconductors in a system. Backers say the resulting stack, besides saving space, can deliver performance akin to the creation of a three-dimensional block of circuitry.

IBM, which makes microprocessors in its own factories and offers chip-production services to others, has been refining the concept with various partners. So has Micron, the sole U.S. company left that makes chips known as DRAMs, for dynamic randomaccess memory.

Under a collaboration between the two companies, Micron would slightly modify some of its memory chips to remove circuitry that normally connects them to other chips. Those functions would essentially be taken over by a special IBM chip, which would be form the bottom layer below a stack of four or eight Micron memory chips.

Rather than communicate through the standard wiring on the outside of packaging which draw signals off the edge of chips the data would flow vertically in the stack of chips using pathways called through-silicon vias. Prototypes of the approach pump some 128 gigabytes of data per second, the companies say, about 10 times more than memory chips typically send now.

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