This research award in the Inorganic, Bioinorganic and Organometallic Chemistry program supports work by Professor Gregory S. Girolami at the University of Illinois at Urbana-Champaign to develop new and better-performing materials and new fabrication methods that will enable the continued miniaturization of integrated circuits. This research involves the synthesis and characterization of new transition metal compounds that could serve as precursors for the low-temperature growth of thin films, and the use of these compounds to deposit thin films. A particular focus is on the chemistry of compounds that contain both transition metals and boron, which could serve as precursors to grow films of transition metal borides, which are highly electrically conductive but extremely chemically inert. The chemistry and mechanisms of film formation will be studied in order to obtain a better understanding of the deposition chemistry and to guide the development of better methods. Both graduate and undergraduate students will participate in the research, and receive advanced training and mentoring that will enable them to contribute to the solution of key national needs.
This project addresses critical problems in the microelectronics industry. Potential outcomes of the work are the development of methods and materials for barriers that would prevent undesired reactions between copper and silicon, which are two key components of integrated circuits, and the development of improved methods to deposit uniformly-thick films in deep recesses with aspect ratios of greater than 10:1, so that key circuit components such as interconnects and dynamic random access memory (DRAM) capacitors can be made on a smaller scale.
A vital national scientific need is the development of new and better performing materials that will enable the continued miniaturization of integrated circuits. One class of materials that have very attractive properties for such applications is the metal diborides, compounds formed by chemically combining a metal such as titanium with the element boron in a 1:2 ratio. The metal diborides have extremely high melting temperatures near or above 3000 °C, and have very low electrical resistivities that rival those of platinum metals. They are also extremely hard and chemically inert. This combination of properties make the metal diborides potentially useful for several applications in the manufacture of integrated circuits. Despite these attractive attributes, transition metal diborides have not been previously used in microelectronics, due principally to the lack of effective methods to make them as high quality films at temperatures compatible with the manufacturing limits for integrated circuits, i.e., below 400 °C. Among the intellectual merits of this completed project, we developed new low temperature methods to grow metal diborides by a technique called chemical vapor deposition, in which chemical compounds (called precursors) are passed over a surface, and a chemical reaction occurs to grow the metal diboride material as a thin film. We also discovered over three dozen new compounds that are currently being tested as precursors for future chemical vapor deposition methods. Specific broader impacts include the education and training of new B.S. and Ph.D. chemists, including multiple students from underrepresented groups. The results have been broadly disseminated by presentations at international conferences, by publication in reputable scientific journals, and by news stories that discuss the work as well as the enabling role of NSF. Interactions with leading companies in microelectronics development, especially IBM and Intel, led to presentation and discussion of the project results with their research and development scientists.
