Laser ablation of silicon wafer with a water microdrop

We have developed a new laser ablation process using a water-microdrop with a diameter of 70 μm. The shapes of the debris were investigated at various delay times. A Q-switched Nd:yttrium-aluminium-garnet laser of 25 ns pulse width and 532 nm wavelength was used. The spattering of debris was remarkably reduced by using the water microdrop. The debris pattern was dependent on the shape of the microdrop on the wafer, which in turn was dependent on the surface condition of the wafer and the delay time. The use of a smaller microdrop would result in laser dicing with a small ridge at the rim of the ablation point and no debris. The flexural stress of 720 MPa was obtained near the blade dicing.