In microfabrication, photolithography – or UV lithography (UVL) – describes the transfer of a geometric pattern from a photomask to a light-sensitive chemical photoresist (substrate) based on photon absorption. In this way, complex integrated circuits or CMOS wafers, for example, go through several photolithographic cycles. Laser lithography, an application of multiphoton absorption, enables localized but high-resolution exposure of photosensitive material. In contrast to their environment, the exposed areas show a different chemical solubility and also allow the generation of extremely complex 3D structures whose structures are in the submicrometer range. Laser lithography is considered as a key technology in many fields. This includes nano- and microelectronics, fluidics, and biotechnology. In most cases, short laser pulses in the (sub-) nanosecond range are used.
Other techniques such as laser interference lithography (LIL), nano-imprint lithography (NIL), and stereolithography (SLA) are methods for patterning regular arrays of fine details and 3D prototyping for medical and biotechnology applications without using complex optical photomasks.