Fabrication of GdBa2Cu3O7−ẟ fine patterns by “chemically modified self-photosensitive” photolithography

Abstract

In this study, GdBa2Cu3O7−ẟ (GdBCO) sol with ultraviolet (UV) sensitivity was prepared using Gd(OAC)3, Ba(OAC)2, and Cu(OAC)2 as the starting materials, methanol as the solvent, and 2,2′-bipyridine as the chemical modifier. Furthermore, chelation mechanism of the chemical modifier and metal ions in the sol was analyzed by infrared and UV absorption spectroscopy. Cu2+ in the sol was found to chelate with the chemical modifier to form a photosensitive chelate, rendering UV sensitivity to the sol. Next, the photosensitive chelate was decomposed by exposing it to UV light, and the decomposition product was barely soluble in organic solvents. By exploiting the self-sensitivity of GdBCO, fine patterns of its films were obtained (without photoresist throughout) with micron scale resolution. XRD and superconductivity performance tests revealed that compared to the GdBCO film without fine patterns, fine-patterned GdBCO fabricated herein does not exhibit significant degradation in terms of its crystal structure and superconductivity. This result indicates that fine-pattern technology developed for chemical film formation is simple in terms of process and equipment, and it does not affect the performance of the GdBCO film. Therefore, “chemically modified self-photosensitive” photolithography can be applied for the preparation of the GdBCO-based inorganic microstructure, which exhibits specific significance for the research and application of high-temperature superconductor electronic devices. In addition, during heat treatment, the technology of first introducing carbon dioxide and then water vapor also was adopted in this paper, which reduced the surface roughness of the GdBCO film.