Impact of Multiple Debonding on Adhesion Energy

Abstract

Direct bonding energy relates to the well-known “strength” or “toughness” of wafer direct bonding interface. It is the energy needed to separate two bonded surfaces. In contrast, adhesion energy is the energy available to bring the two surfaces together. Due to hysteretic effects, the two energies may be different and, while the first energy has been largely measured, the second one is the subject of very few papers. In this study, a new phenomenon will be shown in adhesion energy behavior using two silicon wafers. Several partial debondings and rebondings of the same silicon direct bonding structure result in an increase of the bonding wave speed and consequently of the adhesion energy. Using an electrostatic field, it will be shown that this behavior is linked to the electrical states of the bonding interface. This phenomena is not well understood, although it sheds new light on the adhesion mechanism.

Edge Bonding Voids Management Using Humid Helium Bonding Atmosphere

“…This overpressure deforms the silicon wafers, and this deformation can be seen from the wafer backside. In addition to infrared visualization, dynamic backside interferometry can be used to monitor the bonding wave speed [4]. This overpressure can reach a few bars [2].…”