AVS 50th International Symposium
    Manufacturing Science and Technology Monday Sessions
       Session MS-MoM

Paper MS-MoM9
Development of a Continuous Generation/Supply System of Highly-concentrated Ozone Gas for Low-temperature Oxidation Process

Monday, November 3, 2003, 11:00 am, Room 309

Session: Process and Equipment Integration and Development
Presenter: S. Ichimura, National Institute of Advanced Industrial Science and Technology (AIST), Japan
Authors: S. Ichimura, National Institute of Advanced Industrial Science and Technology (AIST), Japan
H. Nonaka, National Institute of Advanced Industrial Science and Technology (AIST), Japan
Y. Morikawa, Meidensha Corporation, Japan
T. Noyori, Meidensha Corporation, Japan
T. Nishiguchi, Meidensha Corporation, Japan
M. Kekura, Meidensha Corporation, Japan
Correspondent: Click to Email
Ozone has various superior characteristics compared to oxygen molecules in ultrathin oxide film formation on silicon. It realizes rapid oxidation rate at low substrate temperature, very thin transition layer in the oxide film, high electrical quality of the oxide film, etc. Those characteristics have been proved using a highly concentrated (HC) ozone generator, which supplies almost 100% ozone gas at pressure lower than 1000 Pa. The generator utilizes vaporization of pure liquid ozone accumulated in an ozone vessel. Since the liquid ozone accumulation is limited to 5 ml because of safety, the generator can supply only about 360 l ozone gas at the pressure. Considering future need in practical low-temperature oxidation process, we have developed a new system which continuously generate/supply HC ozone gas. The system is equipped with 4 ozone-vessels, and each vessel temperature can be controlled separately. During continuous operation, the condition of each ozone vessel changes stepwise with the same time interval along the following mode sequence; 1) cooling the vessel from 120K to 90K, 2) accumulation of liquid ozone by distillation of ozone/oxygen mixture gas at 90K, 3) heating the vessel from 90K to 113K and vaporization of pure liquid ozone, and 4) heating the vessel from 113K to 120 K and evacuation of the vessel. Allocating one of the 4 modes to each of the 4 ozone vessels so as to cover all the modes simultaneously, the system can supply constant flow of HC ozone gas. The maximum flow rate of the gas is 60 sccm, being enough for single wafer processing, and the ozone concentration is over 99 vol.% at the output of the system. The characteristics of the system in the formation of ultrathin oxide on 4 inch silicon wafer is examined, together with the effect in low temperature oxidation of excited state atomic oxygen which can be generated/supplied by photo-dissociation of ozone at sample position. @FootnoteText@@footnote 1@T. Nishiguchi et al. Appl. Phys. Lett. 81, 2190 (2002).