Advances in laser-based lithography and processing of semiconductors and insulators

The mass production of electronic and optoelectronic devices and even their research and development phase have relied so far to a large extent on optical lithography, implemented via application of pre-fabricated templates (masks), required to selectively expose parts of the substrate to deposition or removal of functional materials. Even a simple device structure may require numerous masks, in order to form the necessary 3D architecture of interconnected semiconductor, dielectric, and metal segments. At the stage of development of many devices and applications, it is necessary to test many different architectures and parameters of each of the components. A viable alternative to the traditional mask-based lithography, at least for µm or sub-µm components and devices, is a direct optical patterning of the substrates, functional layers, protective coatings or electrodes. There are two different ways of implementation of direct optical lithography, referred to as maskless optical lithography and direct laser writing, respectively. A variety of materials and their role in devices or applications have been addressed by these techniques. In particular, the local removal of material, or its recrystallisation, or changing its composition, reduction or oxidation, etc., result in changes of optical, electrical or mechanical properties of the treated material at the µm or sub-µm scale. In the present review we summarize the recent advances and current limitations of these approaches when applied to semiconductor and dielectric materials, including their nanostructures, such as 2D materials and quantum dots.