A New Evaluation Method of Bonding Strength Using Atomic Force Microscopy

As the demand for high-performance semiconductors continues to increase, research on semiconductor chips with 3DICs (three-dimensional integrated circuits) has been intensively conducted. The wafer-to-wafer (W2W) or die-to-wafer (D2W) bonding process is an essential technology for the fabrication of 3DICs. Since the bonding stre7ngth (B/S) affects not only the durability of the product but also reliability of subsequent processes such as wafer back-grinding or CMP, the evaluation of the B/S is an important procedure. The conventional method of measuring B/S is the double cantilever beam (DCB) method which inserts a blade between the two wafers to measure the length of separation. However, the DCB method is a destructive method and the measured sample should be discarded. In this paper, a non-destructive and resource-efficient evaluation method of B/S is newly proposed by measuring the adhesion force using atomic force microscopy (AFM).