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A method of removing the photoresist using ozone gas with acetic acid vapor has been developed. Glass substrates ͑size 100 ϫ 100 mm 2 ͒ coated with I-line resist were treated under the conditions of substrate temperature, (T S ) 27-50°C; acetic acid vapor, 2-18 vol %; ozone, 0-9.3 vol % ͑0-200 g/m 3 ͒; total gas flow rate, 2 L/min; and gas pressure, 100 kPa. A previous ozone treatment with oversaturated water vapor or sprayed water overcame the limitation of ozone diffusion into the resist by the control of the water film on the resist. In this study, pure acetic acid vapor has been first applied for the resist removal by ozone in order to improve the oxidation rate of the resist, because acetic acid is an inactive solvent in the ozonization, and the solubility of ozone is much higher than water. It was observed that the resist removal rate increased with acetic acid and ozone concentration, and reached at 6 m/min at T S ϭ 50°C, which was about six times greater than that of the previous ozone treatment. Metal corrosion of molybdenum and aluminum electrodes was found negligible during the ozone treatment with acetic acid vapor. The mechanism of resist removal without the metal corrosion by ozone with acetic acid vapor is also discussed, based on the solubility of ozone in acetic acid and the corrosion current in ozonized solutions.

Silicon dioxide (SiO2) films formed by chemical vapor deposition (CVD) were treated with oxygen radical oxidation using Ar/O2 plasma excited by microwave. The mass density depth profiles, carrier trap densities, and current-voltage characteristics of the radical-oxidized CVD-SiO2 films were investigated. The mass density depth profiles were estimated with x ray reflectivity measurement using synchrotron radiation of SPring-8. The carrier trap densities were estimated with x ray photoelectron spectroscopy time-dependent measurement. The mass densities of the radical-oxidized CVD-SiO2 films were increased near the SiO2 surface. The densities of the carrier trap centers in these films were decreased. The leakage currents of the metal-oxide-semiconductor capacitors fabricated by using these films were reduced. It is probable that the insulation properties of the CVD-SiO2 film are improved by the increase in the mass density and the decrease in the carrier trap density caused by the restoration of the Si-O network with the radical oxidation.

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We have investigated the changes of chemical bonding states of an H-terminated silicon surface under inert gas (Ar,N 2 ) and ultrahigh vacuum ͑UHV͒ annealing using X-ray photoelectron spectroscopy ͑XPS͒ and thermal desorption spectroscopy ͑TDS͒. SiC is formed ͑corresponding to ϳ0.1 monolayer͒ under inert gas and UHV annealing at around 500°C, which is coincident with the temperature of the dangling bonds formation at the silicon surface by hydrogen desorption, whereas SiC is not formed under O 2 annealing. From the precise analysis using a combination of XPS and TDS, the SiC formation is related to the reaction between the silicon surface and the organic contamination that is unavoidably adsorbed during air exposure. We also studied the electrical properties of metal oxide semiconductor capacitors with a chemical vapor deposited silicon oxide gate insulator formed on Ar-and O 2 -annealed silicon surfaces. Ar preannealing increases the leakage current by approximately 10 Ϫ4 times compared with O 2 annealing.It is of great importance to obtain high reliability in less than 1.5 nm thick silicon oxide gate dielectrics for 65 nm metal oxide semiconductor ͑MOS͒ devices. Pyrogenic oxides have been frequently applied for the gate dielectrics up to the present. In a conventional furnace, an uncontrollable oxide layer is grown at low temperatures in the preannealing process because O 2 gas in the air unavoidably enters the furnace chamber simultaneously at the wafer loading step. 1 The growth of the uncontrollable oxide layer deteriorates the reliability of the gate dielectrics because the time-dependent dielectric breakdown ͑TDDB͒ characteristic of a MOS capacitor with silicon oxide film grown by dry O 2 at low temperature is inferior to that with a pyrogenic oxide film grown at high temperature. 1 A furnace equipped with a load lock chamber that can control residual O 2 is necessary to prevent the uncontrollable oxide layer formation. H-termination with HF treatment is also necessary to remove the chemical oxide layer formed by the RCA cleaning process and to deactivate the silicon surface. 2-7 Although the uncontrollable oxide or the chemical oxide layer is only about 1 nm thick, it is necessary to prevent the formation of these oxide layers to realize 1.5 nm thick, highly reliable gate dielectrics. Previously, it was reported that the TDDB characteristic for MOS capacitors degrades when using a load lock chamber after HF treatment. 8 It would be caused by remaining organic contamination or etching on the silicon surface by residual O 2 and H 2 O. 9,10 However, a microscopic mechanism for the TDDB degradation still remains unclear.In this paper, we investigate the influence of inert gas (Ar,N 2 ) and ultrahigh vacuum ͑UHV͒ annealing with a load lock chamber on the chemical bonding state and roughness of H-terminated silicon surfaces by X-ray photoelectron spectroscopy ͑XPS͒ and thermal desorption spectroscopy ͑TDS͒ analysis and atomic force microscopic ͑AFM͒ observation. The insulation characteristics of gate dielectric...