Double cantilever beam bonding energy measurement using confocal IR microscopy

Abstract

A new technique is assessed in order to measure, at the wafer scale, direct bonding energies. It is derived from the standard Double Cantilever Beam (DCB) method and uses interferometry in confocal IR laser source microscopy to measure crack openings. Such a bonding energy measurement protocol has better accuracy compared to other techniques. This is due to a better confocal microscopy resolution and the high intensity of the laser source. The elastic energy stored in bent wafers is obtained by measuring the beam curvature. DCB deformation models are discussed from the short-range crack opening theory to long distance beam-bending theories. Comparison is made between models, experimental results, and FEM simulations. Finally, the bonding energy error during standard measurements is estimated.