Direct Wafer Bonding of SiC-SiC at Room Temperature by SAB Method

Abstract

The efficiency improvement of power devices is of significance because the energy saving and prevention of global warming are urgent issues. However, it is difficult to realize further improvement by using the conventional silicon (Si) because of its limited physical properties. Silicon carbide (SiC) has attracted considerable attention owing to its superior properties such as wider band gap, higher dielectric breakdown field, higher thermal conductivity, higher stability in a harsh environment, and so on [1-3]. With successive breakthroughs in aspects of material technology and device fabrication such as 6-inch 4H-SiC wafer being and various devices becoming commercially available, SiC power devices will be widely used in the foreseeable future [4]. As a result, the fabrication and integration technologies of SiC power device in mass production will be very important. Wafer bonding is a widely used technology for device fabrication and integration, while studies about directly wafer bonding of SiC-SiC at low temperature are still hardly. Therefore, directly wafer bonding of SiC-SiC at room temperature by SAB method was investigated in this work. In the directly wafer bonding process, the two SiC wafers surfaces were firstly activated by argon fast-atom-beam (Ar-FAB), followed by directly contacted in UHV bonding chamber under a certain pressure. After bonding, a scanning acoustic microscopy (SAM) was used to inspect the voids of the bonded wafer, followed by blade insertion method to test the bonding strength. In addition, the bonding interfaces were analyzed by high-resolution transmission electron microscopy (HR-TEM) and energy-dispersive X-ray spectroscopy (EDX). References M. B. J. Wijesundara, and R. G. Azevedo, Silicon carbide microsystems for harsh environments (Springer, New York, 2011), pp. 15.Y. Hijikata, Physics and Technology of Silicon Carbide Devices, (InTech, Rijeka, 2012) pp. 181.T. Kimoto, Symp. VLSI Technology, 2010, p. 9.H. Okumura, MRS. Bull. 40, 439 (2015).