Could You Build A Better iPod?

…and what do consumer electronics have to do with chemical and biomolecular engineering anyway?

Plenty, if you work at the Laboratory for Advanced Materials Processing (LAMP). It's there that Associate Professor Raymond Adomaitis focuses on the research and development of the next generation of semiconductor products like computer chips.

The Programmable Vapor Deposition System was designed, built and patented by Associate Professor Raymond Adomaitis. It is the first device of its kind to explicitly control the chemical composition of the gas injected above a silicon wafer before it is depositied. This allows researchers to apply the same materials in different thicknesses across a single wafer, creating a graded change and nearly infinate composition possibilities in a single test.

The circuits that make up today's computer chips are manufactured on a micron scale, so tiny that no physical tool is small enough to build them. Instead, they are built through chemical reactions. Exceedingly thin, photosensitive films are spread across a silicon wafer. The wafer is then exposed to tiny patterns of light, and much in the same way film is developed, a chemical reaction creates tiny transistors where the film has reacted with the light. The unexposed areas are then removed, and the tiny transistors are transferred via another coat of film to their final destinations. This process must take place in a clean room, since even a speck of dust can ruin everything at this scale.

Our ability to manufacture tiny, fast, and reliable computer chips in this way allows us to have iPods, flash memory, thin cell phones, and increasingly smaller gadgets. Because the films involved in the process measure only tens of atoms in thickness, the challenge is to distribute a uniform coat of film across the wafer. Inconsistencies in the film will result in transistors of varying quality and performance. The material the film is made of also affects the nature of the final product. LAMP is addressing these issues in two ways: with physical experiments, and virtually through simulations.

Physical experiments are analyzed using the lab's four-point probe, which creates 3-D representations of the sufraces of silicon wafers.  The representations allow LAMP researchers to determine how consistent the thicknesses of the film deposits are, and see the results experiments involving changes in production conditions and materials.

Using computer simulations of chemical reactions, the LAMP team is able to predict how different films will behave under different conditions before actual manufacture, saving time and money. The simulations' data are then saved in a standardized database other scientists and manufacturers can refer to in their own research and development. The LAMP team can also make recommendations to improve existing processes.