Photolithography in anisotropically etched grooves

This paper presents a novel approach for printing patterns into anisotropically etched grooves of silicon wafers or onto other three-dimensional structures. The key to the technology is electrodeposition of photoresist, which yields a nearly conformal polymer coating even on highly textured surfaces. The photosensitivity of the resist is highest for the major mercury lamp emission lines. The resist may therefore be exposed with standard exposure tools reminiscent of microchip fabrication. The deteriorating influence of diffraction effects on image quality upon exposure through a shadow mask is presented together with appropriate countermeasures. Furthermore, a method is proposed to suppress reflections from planes with non-perpendicular incidence of radiation, e.g., sidewalls of anisotropically etched grooves.