Laser writing of amplitude masks and binary holograms on Si/Cr films with layer-by-layer selective etching

Subject of study . This study presents a method for fabricating masks and holograms based on thermochemical laser writing (TLW) on Si/Cr films, followed by layer-by-layer selective etching. Aim of study. The aim of this study is to eliminate the drawbacks of TLW on Cr films by depositing a Si capping layer and introducing an additional stage of selective etching. Method. In conventional TLW on Cr, a latent oxide image is formed and then developed in a selective etchant. The presence of a Si layer on the Cr film during TLW leads to the formation of a metal–silicide mask (MSM), which is developed through the additional etching of the unexposed areas of the Si film. Main results. The results show that, compared to single-layer Cr films, Si deposition expands the usable power range of the laser beam for writing masks on Cr films by up to 3.3 times and increases the spatial resolution by 20%. The resulting MSMs are developed through two-stage etching, which provides exceptionally high selectivity with respect to both Si and Cr. Practical significance. The high selectivity of the modified areas of the Si/Cr film minimizes errors during mask development in the Cr etchant. The significant change in light reflection from the modified Si/Cr film enables the control of the formed pattern prior to development.