Two Cornell doctoral students have received graduate fellowships from the Semiconductor Research Corporation (SRC), the microchip industry's research consortium.
Leonard Harris, a second-year graduate student in chemical engineering, and Christianto Chih-Ching Liu, in his second year of study in electrical and computer engineering, each will receive complete funding for their tuition and fees and a living stipend for up to three years of study.
SRC also places students with industry mentors and internships as part of this program. Harris and Liu are among 28 graduate students from 18 universities chosen for the awards this year.
"These 28 young men and women are among the brightest students in the world," said Virginia Wiggins, SRC manager of student relations. "The semiconductor community looks forward to their contributions to the industry and the innovations they will impart to all of our lives."
Harris grew up in Cos Cob, Conn., then moved to Highland Ranch, Colo., where he attended Highland Ranch High School. He received his undergraduate degree from the University of Colorado-Boulder.
At Cornell he has been conducting research under Paulette Clancy, Cornell associate professor of chemical engineering, creating computer simulations of the defects that develop in silicon when doping atoms are added by ion implantation. "Doping" is part of the process of making transistors: When atoms of an impurity such as boron are inserted into silicon, they displace some of the silicon atoms in the crystal structure, creating free electrons and "holes" that can conduct electricity. However, the displaced silicon atoms may create defects elsewhere in the crystal that interfere with the working of the transistor.
"In larger structures, this isn't a problem, but as we make devices smaller and smaller it becomes a problem," Harris explained.
Liu was born in Taiwan, but his family moved to Victoria, British Columbia, where he attended St. Michaels University School. He received his undergraduate degree from California Institute of Technology, then came to Cornell.
His research with Sandip Tiwari, Cornell professor of electrical and computer engineering and director of the Cornell Nanofabrication Facility, concerns the investigation of three-dimensional integrated circuits. Currently most circuits consist of an array of transistors and other components on the flat surface of a semiconductor chip. One problem with this design is that the tiny wires connecting components must sometimes follow involved, winding routes to get from one place to another without crossing. A three-dimensional circuit consists of several device layers, allowing both higher circuit density and shorter vertical connections, thereby making the chip much faster and interesting new applications feasible.
Liu has investigated the architecture and circuits that benefit most from such a three-dimensional integration approach, and has analyzed thermal issues in large-scale three-dimensional integration. He is using computer simulations to find out what kinds of circuits will benefit most from three-dimensional integration and is studying the problems raised by the additional heat generated in such close-packed circuits.
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