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Proceedings Paper

Patterning and bonding of TiNi shape memory thin film for fabrication of micropump
Author(s): Eiji Makino; Takashi Mitsuya; Tae Nakatsuji; Takayuki Shibata
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Paper Abstract

In order to develop a micropump driven by shape memory actuation, we require a TiNi diaphragm structure with a cap to act as a chamber for applying bias pressure to the diaphragm. With the purpose of realizing such a structure, we studied the photoetching of TiNi thin film on a Si substrate and two bonding processes-diffusion bonding and anodic bonding- for patterning and assembling. TiNi thin film deposited on Si substrates by flash evaporation was etched in HF/HNO3/H2O solutions using negative photoresist masks. HF:HNO3:H2O equals 1:1:4 solution proved capable of etching it at a rate of about 30 nm/s without etching of the Si substrate. Patterned TiNi thin film of 6 micrometers in thickness on a Si substrate was diffusion bonded to another Si substrate coated with the same TiNi thin film at a thickness of 300 nm. Bonding was conducted in a vacuum at a bonding pressure of 210 MPa. TiNi-TiNi diffusion bonding was obtained at temperatures of more than 300 degrees C. A 4-point bending test revealed that the bond strength of specimens bonded at 400 degrees C was 15-20 MPa. Anodic bonding was conducted between TiNi thin film on a Si substrate and a Pyrex 7740 glass substrate at an applied voltage of 600 V. Two substrates were bonded in nitrogen ambient at temperatures of more than 350 degrees C, giving a bond strength of about 15 MPa at 400 degrees C bonding.

Paper Details

Date Published: 10 March 1999
PDF: 8 pages
Proc. SPIE 3680, Design, Test, and Microfabrication of MEMS and MOEMS, (10 March 1999); doi: 10.1117/12.341172
Show Author Affiliations
Eiji Makino, Hokkaido Univ. (Japan)
Takashi Mitsuya, Hokkaido Univ. (Japan)
Tae Nakatsuji, Hokkaido Univ. (Japan)
Takayuki Shibata, Hokkaido Univ. (Japan)

Published in SPIE Proceedings Vol. 3680:
Design, Test, and Microfabrication of MEMS and MOEMS
Bernard Courtois; Wolfgang Ehrfeld; Selden B. Crary; Wolfgang Ehrfeld; Hiroyuki Fujita; Jean Michel Karam; Karen W. Markus, Editor(s)

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