AVS 50th International Symposium
    Manufacturing Science and Technology Tuesday Sessions
       Session MS-TuP

Paper MS-TuP3
GaAs Recycling using Supercritical Fluid SCFCO@sub2@ with O@sub2@ and H@sub2@O

Tuesday, November 4, 2003, 5:30 pm, Room Hall A-C

Session: Poster Session
Presenter: T. Momose, Miyagi National College of Technology, Japan
Authors: T. Momose, Miyagi National College of Technology, Japan
O. Otomo, Miyagi National College of Technology, Japan
Correspondent: Click to Email
Contamination with valuable and poisnous metals such as GaAs dust produced in semicondutor technology must be controlled not to contaminate our life cycles. Most of the metals are embeded underground sealed by concrete, but not complete. Therefore, supercritical fluid (SCF) carbon dioxide (CO@sub2@) with high solubility for organic compounds was employed for simpler recycling for metals.@footnote 1@ Samples were GaAs(1:99) grains obtained from the wall of the sputtering apparatus. They(0.5 g) were kept in SCFCO@sub2@ with H@sub2@O of 4 c.c. for 30 min at a constant temperature and pressure. The treated water was analyzed using ICP (Vop-MarkII, Kyoto-Koken or Z-5700, Hitachi). However, the solubility of GaAs using SCFCO@sub2@ with H@sub2@O was low about 30 mg/L for As @footnote 2@. Therefore, to increase solubility, oxygen gas (O@sub2@) was introduced into the treatment chamber and SCFCO@sub2@ was filled and treated. The solubility at 50 °C for 30 minute was 3 g/L at 10-30 mega-Pascal (MPa) in SCFCO@sub2@ with O@sub2@ of 0.05 MPa and 6 g/L at 25 MPa in SCFCO@sub2@ with O@sub2@ of 0.15 MPa. The addition of O@sub2@ into SCFCO@sub2@ is effective to increase the solubility of Ga about two orders.@footnote 1@ T.Momose et.al, JVST, A17(4), Jul/Aug, 1999, 1391.@footnote 2@ T.Momose et.al, Proc. 55th Appl. Phys. Tohoku Local Conf., 8pB7, Tohoku Univ., Dec. 2000, 198.