Due to the rapid spread of mobile handheld devices, industrial demands for micro-scale holes with a diameter of even smaller than 100㎛ in sapphire/silicon wafers have been increasing. Holes in sapphire wafers are for heat dissipation from LEDs; and those in silicon wafers for interlayer communication in three-dimensional integrated circuit (IC). We have developed a sapphire wafer driller equipped with a 532㎚ laser in which a cooling chuck is employed to minimize local heat accumulation in wafer. Through the optimization of process parameters (pulse energy, repetition rate, number of pulses), quality holes with a diameter of 30㎛ and a depth of 100㎛ can be drilled at a rate of 30holes/sec. We also have developed a silicon wafer driller equipped with a 355㎚ laser. It is able to drill quality through-holes of 15μm in diameter and 150㎛ in depth at a rate of 100holes/sec.
