Experts at CAMP use modeling in a variety of research areas such as chemical-mechanical polishing, quantum physics, and crystal growth. Highlights of CAMP's modeling work are provided.

CAMP Professor Subramanian Models Various Aspects of Chemical-Mechanical Polishing

Professor R. Shankar Subramanian is working on various aspects of modeling of chemical- mechanical polishing (CMP). He is interested in predicting overall removal rates from blanket wafers, and understanding phenomena such as dishing and erosion in patterned wafers. Experimentally measured copper removal rates (from blanket films in a Strasbaugh 6CA polishing tool by an abrasive-free solution containing hydrogen peroxide and glycine) were compared with predictions from a model that accounts for the detailed fluid mechanics in the region between the wafer and the pad, and the associated mass transport with chemical reaction. In the experiments, the removal rate first increased with increasing relative velocity between the wafer and the pad, and eventually leveled off at large velocities. The same trend was predicted by the model. The results were reported in an article published in the journal Thin Solid Films (2001). Professor Subramanian co-authored this article with former doctoral student Lu Zhang.

Professor Subramanian is also interested in the process by which mechanical removal of material occurs at the microscopic level. Here, the issues are the role of the mechanical properties such as the relative hardness of the wafer, abrasive particle, and the pad, the role of asperities on the pad, and the coupling of the chemistry to the mechanical removal process. He and graduate students Lirong Guo and Qingjun Qin have been studying the mechanical removal of copper in an alumina slurry as a function of relative velocity, applied pressure, and particle concentration using a Struers Benchtop polisher. Experiments have been performed using IC-1000 and Suba 500 pads. The results clearly demonstrate the inadequacy of the Preston model in describing mechanical removal rates over a wide range of velocities and pressures in the case of the IC-1000 pad. The removal rates initially increase with increasing pressure or velocity, but tend to level off at sufficiently large values of these parameters. This does not appear to be the case with the soft Suba 500 pads. Work is under way on developing an understanding of the behavior of the removal rate in these experiments.

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Clarkson University Receives $ 30 Million from Wallace H. Coulter Foundation

The Wallace H. Coulter Foundation has made a $30-million commitment to Clarkson University, in support of ongoing excellence in engineering and science programs at the University. Funds devoted to the Colloid Research Focus Area are as follows. An endowment of $6,500,000 will provide faculty salary supplements together with professional development resources, two Wallace H. Coulter graduate fellowships, and an equipment maintenance fund Operating funds of $750,000 will be expended to enhance equipment and facilities to advance colloid science. Also an endowment of $6,500,000 will be devoted to Rehabilitation Engineering and an endowment of $5,000,000 will be given as scholarships to under-represented students. This gift, the largest in Clarkson's history, will dramatically transform the institution and will reinforce and broaden Clarkson's most successful learning and research activities, especially those at CAMP.

The grant will fund key areas, which will support Clarkson's leadership in research and teaching in engineering and the sciences, team project-based learning, and innovative interdisciplinary programs

Clarkson's School of Engineering will be named the Wallace H. Coulter School of Engineering, in recognition of the Foundation's generous gift and the late Wallace Coulter's dedication to the University as a trustee. Wallace H. Coulter was a renowned inventor and entrepreneur. He became acquainted with Clarkson through his collaboration with colloid scientists on the faculty. In 1979 he received an honorary Ph.D. degree, and served as a trustee of the University from 1983-1989. Through the years, Coulter maintained close connections with Clarkson, supporting research projects, collaborating with scientists, and establishing an endowed scholarship.

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