Semiconductor Film Bonding Technology and Application in Two-axis Hall Sensor Fabrication
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1079-N09-03
Semiconductor Film Bonding Technology and Application in Two-axis Hall Sensor Fabrication Keishin Koh, Takashi Matushita, and Koji Hohkawa Kanagawa Institute of Technology, Atsugi, 243-0292, Japan ABSTRACT We study basic problems with semiconductor film bonding technologies and propose a new release method for a large number of semiconductor films using a film photoresist to protect the semiconductor films. We investigated the basic process conditions, released many a large GaAs films, and bonded them to Si, LiNbO3 substrates and a metal Au surface. We estimated the ctystallinity of semiconductor films by X-ray diffraction and Raman spectra. The results demonstrate the effectiveness of these processes. As an application of the semiconductor film bonding technology, we fabricated a two-axis Hall sensor with a planar structure. The two-axis Hall sensor can measure axial and radial magnetic filed components (Bx and Bz) with a sensitivity of about 9.2 Ω/G for Bz and 4.5 Ω/G for Bx. INTRODUCTION The epitaxial liftoff (ELO) process is an attractive material technology [1], as it allows the integration of different electronic or optical film materials on the same substrate and realization of novel functional electronic devices or sensors with new structure, small size, and low cost [2-4]. Recently, a new LSI manufacturing technology combined with bonding technology such as system on chip, and system in package has been developed. The semiconductor film bonding technology based on the ELO process is attracting attention, because it fuses the LSI manufacturing technology with bonding technology. In this paper, we report the results of a study on the basic problems of semiconductor film bonding technologies, such as release and bonding thicker semiconductor film, finding a protective material for semiconductor film, and its application in fabricating two-axis Hall sensors. FILM BONDING TECHNOLOGY The basic process of the semiconductor film bonding technology is based on the ELO process and consists of two process steps, the release of the semiconductor film and its bonding (Figure 1). In the release process, the GaAs compound semiconductor film, which is covered with a protective material, is released into an HF solution by selective etching of the AlAs sacrifice layer. In the bonding process, the GaAs film is bonded onto some other substrate or a metal with a smooth surface using van der Waals force or an adhesive material such as water glass (SiO2 : Na2O) (Figure 1(b) or Figure 1(c)). Compared with the wafer bonding technology, the semiconductor film bonding technology has many features as follows: 1) It can release a large number of small semiconductor film devices from one compound semiconductor wafer simultaneously and the released film devices can be bonded onto a number of other substrate. There is no damage to the compound semiconductor substrate during release process, allowing it to be recycled.
2) The integration density of the functional device is high since the film semiconductor devices are small
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