LT: Removal of Organic Films and Contaminants from Surfaces Using Elevated Pressure, Elevated Temperature Water

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9727249 Hess The worldwide semiconductor market currently exceeds one hundred thirty billion dollars. Continued growth of this technology has occurred because the complexity and hence the capability of microelectronic devices and integrated circuits (ICs) has increased tremendously over the past 3 5 years with essentially no increase in cost per IC chip. Yield and reliability of these devices are determined primarily by the ability to avoid the incorporation of deleterious impurities such as organic contaminants, alkali ions and metal atoms/ions into the device during fabrication processes. Competitiveness and market share in this rapidly changing technology therefore depend on cleaning methodology. Future device structures and dimensions require modifications to the traditional liquid cleaning steps. In addition, disposal of solvents, acids, and large volumes of de-ionized water used in current cleaning techniques is a significant environmental concern. The proposed research focuses on the development of a novel approach to surface cleaning and conditioning that ensures compatibility of this critical fabrication step with vacuum sequences in the manufacturing process. By increasing the pressure of liquid water in the vicinity of 100C, the advantages of liquid cleaning can be maintained; a reduction in pressure results in water evaporation, permitting subsequent transfer of substrates into a vacuum chamber. The addition of C02 to water under elevated pressure and elevated temperature conditions enhances water reactivity to organic materials, and thus provides a means to remove organic as well as inorganic contaminants. Furthermore, this new cleaning approach minimizes the volumes of solvents, acids, and de-ionized water used in the numerous cleaning cycles required in the fabrication of ICs, thereby reducing greatly the environmental impact of IC manufacture. Chemical and physical characterization of silicon and silicon dioxide surfaces, intentional ly contaminated with organic layers and subsequently cleaned, will be performed by X-ray Photoelectron Spectroscopy (via in-situ transfer from the high pressure reactor in the analysis system), in- situ Fourier Transform Infrared Spectroscopy, Inductively- Coupled Mass Spectrometry (ICP-MS), atomic force microscopy and contact angle measurements. These results will provide insight into fundamental cleaning mechanisms of organic contaminants using water with and without additives. Preliminary electrical measurements, combined with ICP-MS, will generate information concerning the ultimate utility of this cleaning technique. ***