When 3:30 PM - 5:00 PM Feb 10, 2012
Where 1670 CSE Building
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Adding New Capabilities to Silicon CMOS Via Determinsitic Assembly


Theresa Mayer
The Pennsylvania State University, Department of Electrical Engineering

The recent International Technology Roadmap for Semiconductors highlighted not only the need to continue Si CMOS miniaturization, but also the growing importance of expanding its capabilities by integrating new materials and devices with the Si circuitry. Attractive materials include narrow bandgap semiconductors that operate at lower supply voltages, giving lower power consumption without sacrificing speed. Molecular and metal oxide materials, which can produce a large electronic response to chemical vapors or biological molecules, offer sensing capabilities. Unfortunately, the high temperatures and harsh chemicals used in conventional fabrication processes generally damage these materials or the Si circuitry, which up to now has made it difficult to effectively couple them.

This talk will describe a programmed deterministic assembly method that offers a route to address this challenge by decoupling off-chip materials synthesis from on-chip device integration. The technique begins by fabricating > 108 nearly identical nanometer-sized parts –sheets, wires, or spheres of a desired material– under optimal conditions, and suspending them in a fluid. Different populations of these components are then delivered, one by one, to a fully processed Si CMOS chip. A programmable AC voltage that is applied to the topmost metal level of the Si chip directs individual parts to a specific region of the chip, and then positions them with the submicron accuracy needed to connect a part to a specific feature on the chip. Assembly follows seconds after delivery, and component densities can exceed 106/cm2. Conventional top-down fabrication is then used to convert the assembled parts into functional devices and circuits. Several material and device integration examples will be discussed, including the assembly of three different types of bio-probe coated nanowire resonator arrays, Si nanowire FETs, InGaAs nanowire p+-i-n+junctions and tunneling FETs.

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