Grad student receives award for microelectronics research

Elham Mohimi, Ph.D. student in MatSE at Illinois, has been selected to receive an Outstanding Graduate Student Award. The award, worth $5,000, was made possible by a generous gift from Lam Research Corporation. Mohimi received her bachelor’s degree in Materials Science and Metallurgy from Bahonar University of Kerman, Iran, and her master's degree in Materials Science and Engineering from Sharif University of Technology, Iran. Her graduate advisor at Illinois is Prof. John R. Abelson; she also collaborates with Prof. Gregory S. Girolami in the Chemistry Department.

"My work at Illinois utilizes chemical control of surface reactions to direct where thin films deposit, which materials are etched, and what morphology they have on complex substrates," Mohimi said. “"t is very exciting for me to develop elegant and effective solutions to real world challenges in science and engineering."

The approaches she uses are part of an emerging new paradigm for the fabrication of nanoscale structures and devices.  In the future, nanoscale devices will be even smaller and more tightly packed than is the case today.

"My work in selective CVD provides a new approach to control surface reaction kinetics through the use of a growth inhibitor. The result is that film deposits only on the desired growth surface, such as a pattern of metal conductors, while no growth at all happens on the intended non-growth surfaces, such as insulators," Mohimi explained. This process would eliminate some of the complex and very expensive patterning and lithography steps, making continued dimensional scaling of integrated circuit devices possible. "The difficult problem of stray nucleation, which limits the practicality of all other selective deposition approaches, is also resolved in this method," she said. "For example, I have successfully demonstrated the selective deposition of copper on metals vs. dielectrics, using the well-known copper precursor Cu(hfac)VTMS, with a co-flow of VTMS as the growth inhibitor. I am also developing processes for thermal atomic layer etching (ALEtch) of metals, a highly challenging area, which brings well-controlled, damage free and precise dry etching routes for nano-fabrication."

After Mohimi completes her Ph.D., she wants to join a leading-edge microelectronics company and "enable progress by translating exciting research, such as the work we have done here, into the manufacturing environment." In the longer term, she might consider an academic or entrepreneurial opportunity.