Quantification of wafer bond strength under controlled atmospheres

Abstract

Bond strength is the most reliable criterion of the wafer bonding quality. The bond strength is affected by the stress corrosion of water from the measurement atmosphere and from the residual moisture at the bonding interface. In this study, we developed a new methodology to measure the wafer bond strength including the water stress corrosion effect under the controlled atmospheres, namely, dry atmosphere, wet atmosphere, and vacuum. The developed method experimentally demonstrates the evaluation of the water stress corrosion of the ambient air and the interfacial water separately. Furthermore, it is also indicated that the wafer stress corrosion depends on the bonding methods, such that the surface activated bonding using Si intermediate layer has high durability for corrosion and the hydrophilic bonding has low durability. This study will provide a new understanding of the relation between the bonding process and the water stress corrosion effect, especially for the interfacial water.

Room-Temperature Bonding of Indium Phosphide Wafers and Their Atomic Structure at the Bond Interface

“…As shown in Figure , no voids or cracks were observed at the interface, indicating that the two wafers were tightly connected and well bonded. The bond strength of the wafers was tested by the crack-opening method, − in which a blade was inserted parallel to the bond interface, the wafer around the blade was split, the crack length was measured, and the surface energy γ (i.e., half the bonding energy G ) was calculated using the following equation γ = 3 E t b 2 t 3 32 L 4 E is the Young’s modulus of the two wafers, t b and t are the blade thickness and thickness of the two wafers, respectively, and L is the measured fracture length. Crack-opening tests were performed at four different locations on the bonded body, and the average bond strength (surface energy) was 0.4 J/m 2 .…”

Surface activated bonding of ALD Al2O3 films

“…This is a well-known phenomenon in SiO 2 bonding, 31) which was also reported for glass bonding and SiN bonding. 32) Therefore, lower bond strength was obtained in humid air. When measurements were done in vacuum, trapped water at the bonding interface would be purged partially as the crack propagates resulting in a possible…”