Researchers at Hewlett-Packard Co. (HP), Palo Alto, Calif., this year announced a series of dramatic breakthroughs that they say demonstrates that molecular electronics could be the semiconductor industry's answer to Moore's Law. The law states that semiconductor performance doubles roughly every two years while the cost to manufacture semiconductors increases at an even greater rate. At that pace, scientists in the industry fear that current silicon-based technology will hit its physical and economic limits by the end of the decade. The molecular electronics advances, the researchers say, could augment silicon-based integrated circuits within the decade and eventually replace them. Silicon-based technology "could be extended enormously by layering molecule-switch devices on conventional silicon without the need for complex and expensive changes to the base technology," says R. Stanley Williams, director of Quantum Science Research (QSR) at HP Labs. In announcing the breakthroughs, HP said that it had:
Created the highest density electronically addressable memory reported to date. The laboratory's demonstration circuit -- a 64-bit memory using molecules as switches -- has a bit density more than 10 times greater than today's silicon memory chips. It is so tiny that 1,000 of the circuits could fit on the end of a single strand of human hair.
Combined, for the first time, both memory and logic using rewritable, non-volatile molecular-switch devices. The rewritable, non-volatile nature of the devices suggests that programming could eventually replace the current high-precision method of fabricating computer chips. "Once a basic grid has been assembled, programming could be used to implement a very complex logic design by electronically setting the appropriate configuration switches in the molecular-scale structure," says Philip J. Kuekes, a researcher at QSR. This would provide manufacturers with flexibility on two fronts, said HP Senior Scientist Yong Chen. First, the device could be manufactured as a generic circuit that can later be programmed for specific customer requirements. Currently most chips must be manufactured for a specific application. Second, the circuits will have greater defect tolerance. When a current silicon-based chip is found to have a defect it must be thrown away. With the molecular chip, designers would be able to use the programmable architecture to route around the defect.
Fabricated the circuits using "nano-imprint lithography," a new manufacturing technology likened in one description to an ultra-high-tech printing press, where entire wafers of circuits can be stamped out quickly and inexpensively from a master. Today's chip manufacturing process involves multiple, precision steps, which make it expensive and error prone. The first products using the technology could be a replacement for flash memory or for use in other high-density, portable devices such as digital cameras. They could be ready in five to 10 years, Williams says. Ultimately, molecular electronics could provide devices so tiny that they would be small enough to be woven into fabric, yet so powerful that they could understand ordinary speech.