Micromachining by lasers

The continually increasing demand for miniaturisation in the fields of electronics, micro-system-technology, and microoptics leads to higher and higher requirements for micromachining tools. Lasers are ideal for micromachining of metals, ceramics, and polymers. UV radiation of excimer lasers and frequency-quadrupled Nd:YAG-lasers with short pulses of 10 ns to 150 ns, and intensities up to 109 W/cm2, allow machining with sub-micron structure size and minimal thermal influence. The high photon energy of UV laser radiation facilitates a direct photolythic interaction with some materials. Besides this, thermal and pyrolytic interaction mechanisms also appear. Regarding this, removal mechanisms of certain materials depending on laser properties are discussed. Handling-systems for micromachining are as important as the laser itself. The application of excimer laser radiation in a multiaxis CNC-micromachining unit with modular design is presented. Special features of this micromachining centre are the beam handling system with integrated flexible mask and energy control. The workpiece handling and all process parameters are controlled by a host computer with a user-friendly interface. The unit can be used to generate microstructures in micromechanical parts and ceramic and polymer surfaces with a resolution of 1 pm horizontally, and 0.1 μm vertically. In this way, it is possible to produce, e.g., microlenses in glass or polymers.