Invention of process for miniaturizing features on silicon chips leads chemical engineer to receive Heroes of Chemistry award
Aug. 23, 2005
AUSTIN, Texas—C. Grant Willson, professor of chemical engineering and of chemistry and biochemistry at The University of Texas at Austin, will receive a 2005 Heroes of Chemistry award from the American Chemical Society for co-developing light-sensitive materials that are used for printing circuitry patterns on all of today's microprocessors and memory chips.
Dr. Grant Willson
|Photo: Jennie Trower|
The revision of this key computer chip manufacturing step became the universal standard for creating smaller, denser computer chips and microprocessors.
Willson, holder of the Rashid Engineering Regents Chair in the College of Engineering, and co-inventor Dr. Hiroshi Ito from IBM’s Almaden Research Center, will receive Heroes of Chemistry awards on Aug. 28 at the national meeting of the American Chemical Society.
Willson and Ito co-developed their light-sensitive materials at IBM when photolithography, the process of patterning computer chips using light, was being questioned as the right approach for future semiconductor manufacturing.
Silicon chips are made through use of photolithography methods, in which light is focused on chemicals to create an image. In the case of computer chips, the light causes chemical reactions in the materials that create templates for placement of tiny wires that make up chip circuits. In the early days of chip-size reduction, the chemicals, or photo-resist materials, would only allow computer manufacturers to print at wavelengths of 365 nanometers or above. This limited chip features to 0.25 micrometers wide, or 300 times thinner than a human hair.
Willson and Ito overcame the 365-nanometer roadblock by creating new materials that respond to shorter light wavelengths that contain more energy, and thus allow finer features to be printed. Their new materials, known as chemically amplified photoresists, allowed for printing of today’s devices, which have minimum features of 90 nanometers, or features 500 times thinner than a human hair.
Their approach was first used commercially in 1986 for IBM chips. It is now used pervasively, and is being used to support future designs for devices with even smaller structures.
Then, as now, building a computer chip involves layering of the microscopic wire patterns. A photoresist material is spread on a silicon layer that will have sections etched away during later processing steps. The image of a stencil, or “mask,” of the wire patterns is projected onto the photoresist material, which permits the exposed parts of the photoresist to become soluble when hit by ultraviolet light. The exposed areas are washed away to reveal the silicon beneath it. The uncovered silicon is etched to create spaces for wiring or other components in each layer of the microprocessor. The smaller these wires can be made, the faster and better the chip works, and the cheaper it becomes.
For more information contact: Becky Rische, College of Engineering, 512-471-7272.