Transfer and handling of thin semiconductor materials by a combination of wafer bonding and controlled crack propagation
- PDF / 297,247 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 83 Downloads / 196 Views
Transfer and handling of thin semiconductor materials by a combination of wafer bonding and controlled crack propagation J. Bagdahn1,2, D. Katzer1 , M. Petzold1, M. Wiemer3, M. Alexe4, V. Dragoi4, U. Goesele4 1
Fraunhofer Institute for Mechanics of Materials, Heideallee 19, D-06120 Halle, Germany. Johns Hopkins University, Department of Mechanical Engineering, 3400 N. Charles Street, Baltimore MD 21218-2681, U.S.A. 3 Fraunhofer Institute for Reliability and Microintegration, Dept. Micro Devices and Equipment, Postfach 344, D-09003 Chemnitz, Germany 4 Max- Planck-Institute of Microstructure Physics, Weinbergweg 2, D-06120 Halle, Germany. 2
ABSTRACT Direct waferbonding is an appropriate technology to join two or more wafers of the same or of different materials. Waferbonding can be used to stiffen thin wafers during fabrication. However, conventional fabrication processes lead to an increase of the bond strength, which inhibits the required de-bonding. The propagation of cracks, which is based on a subcritical crack growth in the bonded interface, was used to cleave the bonded wafers. The subcritical crack growth is limited to the bonded interface, since the adjacent bulk semiconductor materials are inherently resistant to subcritical crack growth. The process allows the separation of Si-Si and Si-GaAs wafers after annealing. Wafer-bonded SOI wafers can also be separated with this technology even if they were annealed at 1100ºC. The first examples for wafer stiffening during fabrication and wafer transfer using the developed approach will be presented.
INTRODUCTION The fabrication of microelectronic, micromechanical and optoelectronic devices requires manufacturing, handling or transferring of thin layers of semiconductor materials with thickness of 250 µm or less. Direct waferbonding is an appropriate technology to join two or more wafers of the same or of different materials /1, 2/. Therefore the bonding of a thin process wafer to a thick substrate wafer can be used to stiffen the thin process wafer and avoid wafer bowing or fracture. In addition, the approach enables the use of conventional high temperature processes such as oxidation, diffusion, or film deposition. However, these steps contribute to a strength increase in the bonded interface and would prevent the required de-bonding, of the process wafer from the handling substrate wafer, without wafer fracture. Therefore, a reliable separation technique for high-strength bonded wafers can be of practical significance. In this paper, we will present a new method /3/, which stiffens thin semiconductor materials during fabrication by direct waferbonding and subsequently promotes controlled cleaving by using subcritical crack growth in the bonded interface. It is the aim of the paper to demonstrate the application of this technique in combination with wafer bonding for the
I9.3.1
handling of GaAs and the fabrication of Si microelectromechanical systems (MEMS) using SOI wafers. CLEAVING APPROACH It was recently shown that subcritical crack growth processes can
Data Loading...
