An Overview of Room Temperature Wafer Direct Bonding: Alignment, Mechanism and Application
Wafer direct bonding, also known as “wafer bonding and “direct bonding , refers to a process to join two wafers without intermediate layer. Since direct bonding does not utilize external intermediate layer, specific metal or adhesive, it overcomes the drawbacks accompanying indirect bonding methods. This technique is more and more widely applied to manufacture of three-dimensional (3D) integration circuits, microelectromechancal systems (MEMS), photonic and biomedical devices. Conventional direct bonding process (e.g. fusion bonding) however often involves high -temperature annealing (>700℃) that limits many applications. To avoid problems arisen from the high-temperature annealing, a surface activated bonding (SAB) method has been developed by our group. In this method, an argon (Ar) fast atom beam is employed to activate the wafer surfaces in ultra-high vacuum environment. Subsequently, the wafers are put into contact at room temperature in no need of heating. The SAB method has been succeeded on homo/heterogeneous bonding of typical wafers used in micro-or optoelectronics, such as semiconductors (e.g. Si, GaAs, InP) and insulators (e.g. LiNbO3, LiTaO3) at room temperature. In order to bond a wider range of materials, the surface activation process is modified in our recent work. Wafer surfaces are cleaned by Ar-ion beam and deposited with Fe nanoadhesion layers simultaneously. The nanoadhesion layers have been found for enhanced bonding. Meanwhile, a fluorine containing plasma activation process is demonstrated to realize a room-temperature bonding in air holding potential for development of the low-cost wafer bonding tool without high-vacuum system. On the other hand, wafer-to-wafer alignment issues are addressed. Based on the alignment and room-temperature bonding processes, the high-precision aligned wafer bonding processes are presented to accomplish with ex-situ and in-situ strategies for wafer-level fabrication of micro/nanoelectronics, photonic and biomedical devices.
Chenxi WANG
Tokyo University, Japan
国际会议
上海
英文
1
2011-08-08（万方平台首次上网日期，不代表论文的发表时间）