Plasma Activated Wafer Bonding as an Alternative to Standard Wafer Bonding Processes

Abstract

Wafer bonding became a powerful industrial technology for various applications in the fields of Micro- Electro-Mechanical Systems (MEMS), wafers stacking for 3D interconnects, wafer level packaging and other areas where new materials combinations are facilitated by the use of different bonding processes. An important enlargement of wafer bonding applications field was brought by new developments in the area of low temperature wafer bonding processes (maximum temperature of 400{degree sign}C): with such processes wafer bonding can be applied for fully patterned wafers (e.g. CMOS), IC wafers (e.g. for 3D interconnects) or silicon direct bonding can now be performed in standard industrial wafer bonding equipment. Plasma activated wafer bonding is a process in which the two substrates are submitted to a plasma treatment prior to bringing them into contact. This surface treatment allows the control of surface chemistry and results in obtaining a high bond strength at low annealing temperatures and short thermal annealing times. This paper reports new results obtained for different applications using plasma activated wafer bonding.