Cleaning Technologies using Electrolytic Ionized Water and Analysis Technology of Fine Structures for Next Generation De
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Mat. Res. Soc. Symp. Proc. Vol. 477 c 1997 Materials Research Society
contamination on Si surfaces [8]. The use of electrolytic ionized cathode water (EIW-C) with high reduction potential is effective in removing inorganic particle such as residual silica particles on wafers after chemical mechanical polishing (CMP) [10]. Electrolysis of UPW also results in highly efficient rinsing [11,12]. Thus, EIW of both diluted electrolyte solutions and UPW have much potential as an ecological and economical wet process for both 300-mm wafer and 200-mm wafer processing. In this paper, we summarize the production, characteristics and cleaning effects of EIW. A second concern regarding next-generation cleaning processes is how to guarantee sufficient cleanliness in fine structures by using a contamination analysis technique for inside the fine structures. The conventional technology for metallic contamination analysis, however, is insufficient for this purpose. For example, analysis methods with high sensitivity, such as total reflection x-ray fluorescence (TXRF) or inductively coupled plasma mass spectrometry (ICPMS), cannot be used for analyzing the inside of deep-submicron structures. Methods that can be used for analyzing these structures, such as field emission Auger electron spectroscopy (FEAES), do not have a sensitivity of less 1014aosc2. We have developed a way to analyze method for the remaining metallic contamination and the residual ions in deep-submicrondiameter holes with high aspect ratios [13]. The method is based on conventional atomic absorption spectrometry (AAS), and uses device patterns with high-density contact holes. With this method, metallic (Fe) contamination on the order of 101 atoms/cm2 can be easily analyzed inside 0.1 -jim-diameter holes with aspect ratios of 10. The residual ions in the fine holes can be detected by thermal desorption spectroscopy (TDS). We have reported that TDS can directly analyze Al compound contamination, such as A1C or Al F, produced in deep-submicron holes during dry etching [14], and as well as residual surfer oxides in deep-submicron holes after SPM cleaning [15]. In this paper, we summarize our new methods for analyzing contamination remaining in deep-submicron-diameter holes. Cleaning Technology using Electrolytic Ionized Water 1. Production of Electrolytic Ionized Water (EIW) 1.1 The Electrolytic Cell The structure of the cell used in this study is shown in Figure 1. The cell is composed of three chambers, which are anode, cathode and middle chambers inside the frames [9]. A pair of sheets of ion exchange membranes separates each chamber, and forms anode, cathode and middle chambers inside the frame. The anode and cathode electrodes are located in the anode and cathode chambers, respectively. An ion exchange resin is packed in the middle chamber. Each chamber has an inlet and outlet nozzle for making individual water flow in each chamber. All parts of the cell except for the electrodes, are made of fluorocarbon polymers, such as PTFE, PFA, and etc. The materials of th
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