Interference Lithography - Uses of Interference Lithography

Uses of Interference Lithography

The benefit of using interference lithography is the quick generation of dense features over a wide area without loss of focus. Hence, it is commonly used for testing photoresist processes for lithography techniques based on new wavelengths (e.g., EUV or 193 nm immersion). In addition, interfering laser beams of high-power pulsed lasers provides the opportunity of applying a direct treatment of the material's surface (including metals, ceramics and polymers) based on photothermal and/or photochemical mechanisms. Due to the above mentioned characteristics, this method has been called in this case “Direct Laser Interference Patterning” (DLIP). Using DLIP, the substrates can be structured directly in one-step obtaining a periodic array on large areas in a few seconds. Such patterned surfaces can be use for different applications including tribology (wear and friction reduction) or biotechnology. Electron interference lithography may be used for patterns which normally take too long for conventional electron beam lithography to generate.

The drawback of interference lithography is that it is limited to patterning arrayed features only. Hence, for drawing arbitrarily shaped patterns, other photolithography techniques are required. In addition, non-optical effects, such as secondary electrons from ionizing radiation or photoacid generation and diffusion, cannot be avoided with interference lithography. For instance, the secondary electron range is roughly indicated by the width of carbon contamination (~20 nm) at the surface induced by a focused (2 nm) electron beam. This indicates that the lithographic patterning of 20 nm half-pitch features or smaller will be significantly affected by factors other than the interference pattern, such as the cleanliness of the vacuum.