Dicing of gallium–arsenide high performance laser diodes for industrial applications: Part II. Cleavage operation

Dicing of III–V based high-power laser diodes is commonly carried out in two steps. To start with, an initial defect is created in the devices by scratching it with a sharp diamond tip to allow a subsequent cleavage operation. Micro-scratching and cleavage are crucial operations for maximizing the yield production. Thus, this contribution is divided into two papers according to these essential operations.The cleavage operation is the focus of this study for three material conditions based on gallium–arsenide (GaAs) previously scratched by a diamond tip (Berkovich). Due to its complexity, the cleavage operation was investigated through (a) finite element calculation, (b) the stress intensity factor K and (c) the cleavage operation itself. It can be demonstrated that a crack significantly diminishes the influence of loading condition. Additionally, three cleavage behaviors were observed depending on the initial conditions. First, the crack deviates from its path. This was observed when the shear stress component becomes more important than the tensile stress. Second, features are visible on the cleaved surface. This is generally the case when the median crack is small resulting in an unstable crack growth leading to catastrophic failure. Finally, perfectly atomic flat cleaved surfaces are produced. This is the case with larger median crack when, after unstable initiation, crack propagation is controlled.The analyzes and results of the scratching operation completed in this contribution are presented in Part I [Wasmer, K., Ballif, C., Pouvreau, C., Schulz, D., Michler, J., 2008. Dicing of gallium–arsenide high performance laser diodes for industrial applications. Part I. Scratching operation. J. Mater. Process. Technol. 198, 114–121]. Based on this complete study, three technological requirements can be set for obtaining cleaved surface atomically flat: (1) crack initiation and propagation must be controlled, even in brittle semiconductors such as GaAs, (2) the scratch load range and tip geometry must be optimized to avoid particle generation and (3) finally, crack opening in Mode I (tension) must be maximized compared to Mode III (shearing).