Preprint: manuscript in review

We report demonstration of a low-cost (~ 1000 USD) interference lithography (IL) system capable of ~ 300-nm-pitch patterning. Our system includes a 405-nm GaN diode laser module, a machinist's block, a chrome-coated silicon mirror, substrate and double-sided tape. The laser and the machinist’s block were assembled in a linear configuration, and to complete the system, the mirror and substrate were taped to perpendicular surfaces of the machinist’s block. During IL exposures, the substrate’s photoresist was irradiated with light from both the laser (directly) and mirror (by reflection). Approximately 50 silicon substrates were prepared with a trilayer resist stack to improve the resist profile and facilitate post-lithographic processing. These substrates were exposed and developed and some of them were then imaged in an SEM. In addition to exposures, the associated laser spectrum was measured, enabling calculation of the laser’s fringe visibility as it varied along the substrate surface. To compare the exposed resist pattern to the fringe visibility, we measured the first order diffraction efficiency as a function of position along the grating surface. Our measurements indicated that the artifacts seen in both the optical spectrum and resulting grating patterns arose from the laser diode source. Consequently, improving the source characteristics will be the topic of future work.