Michael Stewart

Under the direction of the Gift Manager and the Alumni Records & Donor Coordinator of Bradley University, I scan gift and donor documentation, prepare and send Memorial Gift Notifications to family members of the deceased, prepare Matching Gift Letters to donors whose outside employer match gifts to the University, and other responsibilities such as campus errands, filing, verifying computer data against other sources, data entry, and other duties as assigned.

The development of integrated circuits (ICs) with an ever-decreasing feature size, as dictated by Moore’s law, has created a continuing need for understanding molecular interactions occurring at the surfaces involved in a key processing step of IC manufacture - chemical-mechanical planarization (CMP). Characterizing the adsorption of small molecules on colloidal metal oxide abrasive particles is an active area of investigation associated with the development of new CMP polishing slurries. The need for characterizing these adsorptive interactions stems from the increasing use of abrasive particles in CMP slurries with minimized hydrodynamic diameters (< 10 nm) as a means to reduce surface defect creation during CMP processes. However, incorporation of smaller abrasive particles in CMP slurries promotes the adsorption of chemical additives on a slurry’s abrasive particles due to the increase in the total surface area of the abrasive particles. In this presentation, applications of fluorescence correlation spectroscopy (FCS) and attenuated total reflectance infrared spectroscopy (ATR-FTIR) are described for the analysis of small molecule adsorption on colloidal alumina, silica and zirconia abrasive particles. The choice of these particles in this investigation derives from their use in commercial CMP processes for planarizing metal films deposited on silicon wafers during the fabrication of ICs. The reported FCS studies build on previous studies in which fluorescent dyes were used as probes for adsorption sites on colloidal silica abrasives dispersed in aqueous solution. Reported ATR-FTIR analyses expand on earlier studies of the molecular interactions between small molecules and the surface of thin films of a colloidal ceria abrasive. Extensions of these two methods are described for the analysis of small molecule adsorption at additional surfaces involved in CMP processes. (Abstract written by Dr. Edward Remsen)

Small molecule adsorption on CMP slurry abrasive particles has been investigated previously for silica (1) and ceria (2, 3) abrasives using fluorescence correlation spectroscopy (FCS) and attenuated total reflectance - Fourier transform infrared spectroscopy (ATR-FTIR). The need for further characterization of such adsorptive interactions is dictated by the increasing use of abrasive particles in CMP slurries with minimized hydrodynamic diameters (S 10 nm) as a means to reduce surface defects created during CMP processes. incorporation of ever-smaller abrasive particles in CMP slurries will, however, promote the adsorption of chemical additives on a slurry's abrasive particles due to the increase in the total abrasive particle surface area. In the present study, FCS and ATR-FTIR are employed in the analysis of small molecule adsorption on colloidal alumina and zirconia abrasive particles. This work is motivated by the widespread commercial use of alumina-based slurries in CMP processes for planarization of deposited copper films on dielectric layers and the proposed use (4) of zirconia abrasives in CMP slurries for metal film removal on dielectric metal oxide materials. The reported FCS studies use fluorescent dyes as probes for adsorption sites on alumina and zirconia colloids dispersed in aqueous solution. Described ATR-FTIR analyses summarize the characterization of molecular interactions driving glycine and picolinic acid adsorption on porous thin films of colloidal alumina and zirconia, respectively. The potential for employing these methods in studies modelling the adsorption of CMP slurry additives on a metal film deposited on a silicon wafer surface is also discussed. References: 1. Jacobson, L.M.; Turner, D.K.; Wayman, A.; Rawat, A.; Carver, C.T..; Moinpour, M.; Remsen, E.E. Characterization of Particle Size and Surface Adsorption for SiO2 Abrasives Used in Chemical Mechanical Planarization via Fluorescence Correlation Spectroscopy. ECS J. Solid State Sci. Tech. 2015, 4, P5053-P5057. 2. Schorr, D.K.; Smith, M.A.; Rawat, A.K.; Carver, C.T.; Mansour, M.; Remsen, E.E. Fluorescence Correlation Spectroscopic Studies of Particle Properties for Colloidal Ceria Abrasives Used in Chemical-Mechanical Planarization. ECS Trans. 2016, 72, 43-51. 3. Marsh, J.L.; Wayman, A.E.; Smiddy, N.M.; Campbell, D.J.; Parker, J.C.; Bosma, W.B.; Remsen, E.E. Infrared Spectroscopic Analysis of the Adsorption of Pyridine Carboxylic Acids on Colloidal Ceria. Langmuir 2017, 33, 13224-13233. 4. "CMP Composition Containing Zirconia Particles and Method of Use"; Lin, Wiechang; Parker, John; Remsen, Elizabeth; PCT Int. Appl. 2012; US 8,778,212 B2; July 15, 2014. (Abstract written by Dr. Edward Remsen)

The development of a new instrumental capability for simultaneous determinations of molecular size and molecular shape of nanoparticles and proteins is proposed. An existing analytical technique used in the project leader’s laboratory, fluorescence correlation spectroscopy (FCS), will be enhanced for this purpose. Simultaneous measurements of molecular size and shape will have broad application, but will be used initially in conjunction with ongoing and anticipated collaborative research interactions with industrial research partners interested in the development of a robust method for shape analysis of abrasive nanoparticles. This project will advance the field of FCS and will provide future external funding opportunities. (Abstract written by Dr. Edward Remsen)