AVS 46th International Symposium
    Manufacturing Science and Technology Group Monday Sessions
       Session MS-MoA

Paper MS-MoA9
Highly Concentrated Ozone Gas Supplied at Atmospheric Pressure Condition as a New Oxidizing Reagent for the Formation of SiO@sub 2@ Thin Film on Si

Monday, October 25, 1999, 4:40 pm, Room 611

Session: Ultra-Clean Society and Contamination Free Manufacturing
Presenter: K. Koike, Iwatani International Corporation, Japan
Authors: K. Koike, Iwatani International Corporation, Japan
S. Ichimura, Electrotechnical Laboratory, Japan
A. Kurokawa, Electrotechnical Laboratory, Japan
K. Nakamura, Electrotechnical Laboratory, Japan
Correspondent: Click to Email
Ozone is expected to be one of promising oxidizing reagents for the fabrication of future ULSI device. We have investigated ozone oxidation on Si(100) substrate with high purity (about 80 vol%) ozone gas, and have revealed various merits of ozone oxidation; e.g., ozone can form dense SiO@sub 2@ film on a Si substrate at lower substrate temperature than that used at a conventional thermal oxidation process, ozone can oxidize hydrogen-terminated silicon surface which oxygen molecules cannot, etc.@footnote 1,2@ One major problem which has to be solved before the ozone oxidation is applied to a practical process is low oxidation rate. Since the pressure of the high purity ozone gas was low (typically; <10@super -4@ Pa), only 2 nm thick SiO@sub 2@ film could grow on a Si(100) substrate by 2 hours ozone gas exposure at a substrate temperature of 973K. In the present study, we report that the problem could be solved by fabricating another type of ozone generator. The generator can supply highly concentrated ozone gas at atmospheric pressure condition, by desorbing ozone from silica-gel on which ozone/oxygen mixture gas had been adsorbed at lower temperature. Ozone concentration in the gas from the generator can be changed between 0 and 70 vol%, by controlling the ozone adsorption and desorption condition. Even with 25 vol% ozone gas, it was confirmed that SiO@sub 2@ film as thick as 3.3 nm grew on a Si (100) wafer kept at 648 K by 30 min exposure. The wafer had chemical oxide film (thickness; 1.2 nm) before the ozone oxidation. So SiO@sub 2@ film with thickness of 2.1 nm could be additionally formed with the ozone gas, while under the same experimental condition only 0.6 nm thick SiO@sub 2@ film could be formed on the same wafer with pure oxygen. It should be emphasized that the density of the SiO@sub 2@ film formed with 25 vol% ozone gas was equivalent to the density of a film formed by a thermal oxidation process at 1023K, judging from their etching rates with dilute HF solution. The result suggests that the present ozone oxidation process has high possibility to be adopted as a new process for Si oxidation. The details and performance of the new ozone generator are presented together with the dependence of the oxidation of Si(100) on ozone concentration and on Si substrate temperature. @FootnoteText@ @footnote 1@ A. Kurokawa, S. Ichimura, and D.W. Moon, Mat. Res. Soc. Symp. Proc. 477, 359 (1997). @footnote 2@ A. Kurokawa, K. Nakamura, and S.Ichimura, Mat. Res. Soc. Symp. Proc. 513, 37 (1998).