AVS 47th International Symposium
    Manufacturing Science and Technology Friday Sessions
       Session MS-FrM

Paper MS-FrM5
Standardization of the Method to a Disiloxane Concentration in Monosilane Gas using Atmospheric Pressure Ionization Mass Spectrometer

Friday, October 6, 2000, 9:40 am, Room 304

Session: Langmuir Award/Ultra Clean Society and Contamination Free Manufacturing
Presenter: M. Kitano, Tohoku Univ.
Authors: M. Kitano, Tohoku Univ.
Y. Sakakibara, NTT Adv. Tech. Corp.
Y. Ishihara, Nippon Sanso Corp.
Y. Kunii, Kokusai Electric Co., Ltd.
K. Hasumi, Hitachi Tokyo Electronics Co., Ltd.
I. Matsuda, Syowa Denko K.K.
A. Ohki, Osaka Sanso Kogyo Ltd.
Y. Shirai, Tohoku Univ.
Correspondent: Click to Email
Ultra clean society (UCS)'s process gas measurement standardization working group proposed, using atmospheric pressure ionization mass spectrometer (APIMS) which has two ionization compartments to measure the disiloxane(SiH@sub 3@-O-SiH@sub 3@) in monosilane(SiH@sub 4@) gas at concentrations between 10ppb to 1000ppb. In this standard, SiH@sub 4@ with SiH@sub 3@-O-SiH@sub 3@ of unknown concentration is introduced into the second ionization compartment. Ar@super +@ ion generated by corona discharge in the first ionization compartment is sent out to the second ionization compartment. And Ar@super +@ ion reacts with SiH@sub 3@-O-SiH@sub 3@ in the SiH@sub 4@ gas to exchange ion, and SiH@sub 3@-O-SiH@sub 3@ ion are generated in large amount. SiH@sub 3@-O-SiH@sub 3@ is detected with mass number of 77. Using relative ion intensity of SiH@sub 3@-O-SiH@sub 3@ and calibration curve acquired by follow method, SiH@sub 3@-O-SiH@sub 3@ concentration is determined. H@sub 2@O of a known concentration firstly adsorbed into the stainless steel tube. This tube is purged out using SiH@sub 4@ gas. Adsorbed H@sub 2@O reacts with SiH@sub 4@, and SiH@sub 3@-O-SiH@sub 3@ is generated. Adsorbed H@sub 2@O volume and generated total disiloxane volume are in a proportion of one to one. So that the amount of disiloxane in SiH@sub 4@ gas can be quantitatively calculated. The determination limit, which was defined as 3 times of the standard deviation of SiH@sub 3@-O-SiH@sub 3@ concentration in purified SiH@sub 4@ gas was found to be 10ppb. For verification of calibration curve, calibration curves, which were prepared at different timings and different places by different people, showed good agreement of over 80%. Moreover, it is proved that calibration curve of SiH@sub 3@-O-SiH@sub 3@ in SiH@sub 4@ can be substituted by that of H@sub 2@O in Ar which is corrected with a correction coefficient.