SGER: Room-Temperature Reactive Ion Plasmas for the Generation of Low-Friction Carbon Films

Aerospace Corporation, El Segundo CA

Investigators

Abstract

ROOM-TEMPERATURE REACTIVE-ION-PLASMAS FOR GENERATION OF LOW-FRICTION CARBON FILMS Small Grant for Exploratory Research G. Radhakrishnan (The Aerospace Corporation) and Michael McNallan (University of Illinois at Chicago) In this exploratory research program, a novel room-temperature process for the generation of low-friction carbon films from hard carbides is proposed. This offers an alternative to high-temperature chlorination (on the order of 1000oC), typically used to generate such films from carbides. There are practical limitations when applying the high-temperature process to fabrication of microscale devices. Such devices are typically produced by photolithography on a silicon substrate. The Si substrates are highly susceptible to attack by Cl. or F. radicals and must be protected from the halogenation process. However, neither organic photoresist, nor phospho-silicate glass, commonly used as mask materials in device fabrication, are capable of withstanding the high temperatures employed in the chlorination process. For these reasons, an alternative low-temperature is highly desirable. We will investigate the use of reactive halogen-ion plasmas, generated from low-pressure halogen gases using a radio-frequency source, as an alternate method of producing low-friction carbon coatings at or near room-temperature on bulk TiC and SiC as well as thin films of these carbides. Such coatings will simultaneously reduce friction and wear on sliding interfaces in micro and macro-scale devices and surmount key and complex problems that result from high-temperature processing during fabrication of devices with new materials. Specifically, room temperature processing will allow such a technique to be applied to the fabrication of devices using standard photoresist as a masking layer for lithographic patterning. This approach to depositing low-friction and hard coatings at room temperature is new and exploratory. It has the potential of significantly impoacting the MEMS industry by becoming a processing step in the manufacture of many types of complex MEMS devices. This investigation will provide insight into the fundamental mechanisms responsible for the generation of low-friction carbon from carbides by comparing carbon films generated by room-temperature reactive halogen plasmas to those produced by high-temperature chlorination of carbides. In parallel, this investigation could provide a technological breakthrough for fabricating hybrid, multi-functional low-friction coatings for MEMS or other devices impacting micro and nanotechnologies. Novel coatings and hybrid deposition and surface engineering schemes will emerge from this research. This program will also provide an excellent opportunity for students to participate in new developments and applications in materials processing and surface engineering. This collaborative program between the Aerospace Corporation and UIC makes use of complementary experimental capabilities at the two institutions to achieve its research and educational goals. UIC has pioneered the development of high temperature chlorination processes for formation of carbon structures on ceramic carbides, and is well equipped with characterization equipment. The Aerospace Corporation has particular expertise in room-temperature coating technologies, fabrication of MEMS devices, and can offer additional equipment, which can supplement that available at UIC. The technologies used at the two institutions are sufficiently different that a student with experience in both laboratories will be uniquely prepared to contribute to the development of new nanoscale technologies. The collaboration between the two institutions will enable a graduate student from UIC to participate in investigations at The Aerospace Corporation as part of his/her thesis research and gain valuable experience and exposure to the advanced laboratory facilities at The Aerospace Corporation.