SBIR Phase I: Clean Tool: A unified approach to wafer cleaning

This Small Business Innovation Research (SBIR) Phase I project, will develop a new kind of wafer cleaning tool that will be useful at every cleaning step in semiconductor processing. It will use an environmentally friendly, acoustic technology that uses only clean water and silent sound. The tool will clean a wafer by simultaneously detecting and dislodging the particulates from the wafer using UPW (ultra pure water) until all particulates have been removed. Its novelty is that this will be the first tool incorporating the endpoint determined cleaning. It will then rinse the wafer briefly and dry it in the same tool. In this streamlined sequence, a fully clean wafer will be available for the next process step much more quickly, much more economically, and in much less cleanroom space. Cleaning mechanism relies on constructively controlled acoustic microcavitation precisely brought about at the particle location to dislodge the particle; the cavitation implosion echo is simultaneously detected and cleaning kept track of. This tool will be applicable to all sub-100nm technology nodes. It will be able to detect on-wafer particulates well below 50nm. The broader impact/commercial potential of this project beyond semiconductor application will be in precision cleaning of lithography masks, mems, solar cells, flat panel displays, HDDs, and precision optics. Ultimately, the principle of constructively controlled microcavitation relies on controlling the very fundamental process of phase change, the control of nucleation -- the ability to convert a liquid into a gas in the vicinity of a solid phase. This should have much wider applications in a variety of chemical processing, e.g. in the control of the boiling processes in chemical and nuclear reactors. The study of this acoustically mediated nucleation control could form an active field/area of research and education. Rejected wafers amount to a colossal waste of prime resources including energy, material, and productivity time; it further amounts to environmental degradation through the effluents and scrap generated. The use of clean tool to prevent such wafer loss directly benefits the society at large.