Transcending Moore’s Law with Molecular Electronics

The future of Moore’s Law is not CMOS transistors on silicon. Within 25 years, they will be as obsolete as the vacuum tube.

While this will be a massive disruption to the semiconductor industry, a larger set of industries depends on continued exponential cost declines in computational power and storage density. Moore’s Law drives electronics, communications and computers and has become a primary driver in drug discovery and bioinformatics, medical imaging and diagnostics. Over time, the lab sciences become information sciences, and then the speed of iterative simulations accelerates the pace of progress.

There are several reasons why molecular electronics is the next paradigm for Moore’s Law:

• Size: Molecular electronics has the potential to dramatically extend the miniaturization that has driven the density and speed advantages of the integrated circuit (IC) phase of Moore’s Law. For a memorable sense of the massive difference in scale, consider a single drop of water. There are more molecules in a single drop of water than all transistors ever built. Think of the transistors in every memory chip and every processor ever built, worldwide. Sure, water molecules are small, but an important part of the comparison depends on the 3D volume of a drop. Every IC, in contrast, is a thin veneer of computation on a thick and inert substrate.

• Power: One of the reasons that transistors are not stacked into 3D volumes today is that the silicon would melt. Power per calculation will dominate clock speed as the metric of merit for the future of computation. The inefficiency of the modern transistor is staggering. The human brain is ~100 million times more power efficient than our modern microprocessors. Sure the brain is slow (under a kHz) but it is massively parallel (with 100 trillion synapses between 60 billion neurons), and interconnected in a 3D volume. Stan Williams, the director of HP’s quantum science research labs, concludes: “it should be physically possible to do the work of all the computers on Earth today using a single watt of power.”

• Manufacturing Cost: Many of the molecular electronics designs use simple spin coating or molecular self-assembly of organic compounds. The process complexity is embodied in the inexpensive synthesized molecular structures, and so they can literally be splashed on to a prepared silicon wafer. The complexity is not in the deposition or the manufacturing process or the systems engineering.

Biology does not tend to assemble complexity at 1000 degrees in a high vacuum. It tends to be room temperature or body temperature. In a manufacturing domain, this opens the possibility of cheap plastic substrates instead of expensive silicon ingots.

• Elegance: In addition to these advantages, some of the molecular electronics approaches offer elegant solutions to non-volatile and inherently digital storage. We go through unnatural acts with CMOS silicon to get an inherently analog and leaky medium to approximate a digital and non-volatile abstraction that we depend on for our design methodology. Many of the molecular electronic approaches are inherently digital and immune to soft errors, and some are inherently non-volatile.

For more details, I recently wrote a 20 page article expanding on these ideas and nanotech in general (PDF download). And if anyone is interested in the references and calculations for the water drop and brain power comparisons, I can provide the details in the Comments.