Initiation and arrest of cracks from corners in multi-chip semiconductor devices

Abstract

A contemporary semiconductor device often contains multiple chips. Corners of the chips concentrate stress, and are principal sites to initiate failure. Here we propose to characterize the corners using a double cantilever beam, in which two silicon beams sandwich a row of chips. As the two beams are pulled open, a crack initiates at the corner of a chip, and runs unstably on the interface between the chip and a beam. The crack may or may not arrest, depending on various experimental conditions. We calculate energy release rate as a function of crack length by using a combination of finite element method and an analytical solution of the singular field around a corner. At a fixed applied displacement, the energy release rate is low for a short crack, peaks for a crack of intermediate length, and drops for a long crack. This non-monotonic behavior explains how a crack initiates, grows unstably, and possibly arrests. If the crack does arrest, as the two beams open further, the crack grows stably. We relate the initiation and arrest of the crack to machine compliance, specimen geometry, and flaw size. The force at which the crack initiates can be used to characterize the manufacturing process, whereas the stable growth of the crack can be used to measure interfacial toughness. It is hoped that this work will aid the development of multi-chip semiconductor devices.