Experimental study of diode laser cutting of silicon by means of water assisted thermally driven separation mechanism

A novel variant of thermal laser dicing of crystalline silicon has been studied in this paper, by using fluid assistance to improve the reliability, flexibility and operational window of the current process. High quality laser cutting of monocrystalline and polycrystalline silicon is demonstrated by using a diode laser focused on a 1 mm spot, assisted with the use of a water or glycerol layer, and resulting in Zero Kerf cuts with low total roughness and enabling freeform cutting. This variant process is compared with conventional thermal cleaving, with and without the use of an initial stress concentratior, as well as compared with optimized conventional approaches (ablation and gas assisted cutting). Besides the effective cutting speed, the laser induced damage is studied for each alternative, as well as the potential for photovoltaic applications on mono and multicrystalline silicon, is presented. Several parameters have been studied, to achieve highest effective speed values without damage in the surface of the wafer and a homogeneous cutting quality. The high quality, speed and flexibility of water-assisted direct diode induced thermal cutting are demonstrated. (C) 2013 The Authors. Published by Elsevier B.V. Selection and/or peer-review under responsibility of the German Scientific Laser Society (WLT e.V.)