Product Code: ICAL09_M305

Analytical Model for CW-Laser Cleaving of Semiconductors
Authors:
Viktor Schütz, Laser Zentrum Hannover e.V.; Hannover Germany
Oliver Haupt, Laser Zentrum Hannover e.V.; Hannover Germany
Rainer Kling, Laser Zentrum Hannover e.V.; Hannover Germany
Presented at ICALEO 2009

The cw-laser cleaving process strongly depends on the temperature rise in the semiconductor and therefore from the active and passive process parameters. In the past, various methods have been developed to evaluate the process parameters in cw-laser processing of materials. The finite element method is a powerful tool for simulating heat conduction for all kinds of geometries, however, it turns out to be very time consuming. To achieve the targeted adaptation of process parameters in cw-laser processing, the knowledge of changing physical parameters is indispensable. A sufficient description of the cw-laser process at adequate calculation times can be achieved by an analytical model based on the law of conservation of energy. The model is verified by cw-laser heating of a semiconductor. The challenge in modeling controlled cw-laser heating is to include temperature dependencies of all parameters. Therefore, the mathematical description of the process of controlled heating is quite complex. In previous works, simplifications have been made because of this complex behaviour to achieve adequate temperatures. By referencing to the solid-liquid phase transition, the model can be used to simulate this complex heating behaviour. The calculated temperature rise for a semiconductor at different cw-laser powers is presented in detail. The calculations lead to a better understanding of process limits, thermal effects and also combined thermo-optical effects.