New Process For Ybco Films And Their Patterning

Due to its excellent electrical and electronic properties, YBCO superconducting film has attracts great attentions and has wide applications in the field of electronics such as filters, infrared detectors, THz antennas, etc. In the application of YBCO films, the preparation of its fine patterns with high performance plays a key role. The fine patterns of high-Tc superconducting film are usually fabricated by conventional photolithography. During the process of lithographic patterning of the YBCO film, the superconducting performance of YBCO is degraded owing to the YBCO itself properties and characteristics. In order to overcome the disadvantages in method of traditional photolithography, some researches have had put forward some micro-fabrication techniques such as the modification technique and the micro-shadow mask technique. These methods, however, have some other limitations. Therefore, to develop a method of fabrication of YBCO fine patterns, by which the YBCO superconducting properties are not affected by processing, is theoretically significant and of practicable value in developing superconductor devices.In the paper, a new method of fabrication of YBCO film patterns using sol-gel process combined with chemical modification is put forward. The photosensitive chelates are formed in YBCO gel films by adding some chemical modifiers in the sol. When the YBCO gel film is irradiated by the UV light, the solubility of the gel film irradiated drops sharply in some organic solvents such as methanol and ethanol, and thus the gel film exhibits UV photosensitivity. Using this photosensitivity, the fine patterns of YBCO gel films can be prepared by exposing the YBCO gel film to the UV light followed by rinsing process with organic solvents. And thus the gel films exhibit photosensitive to UV light. In this paper, chemical reactions between the chemical modifiers(AA,BzAcH) and metal ions(Cu2+,Y3+), and the formation mechanism of the photosensitive chelates, are explored. And the feasibility of fabrication of film patterns using photosensitive sol-gel method and their properties are also explored. Results indicate that:The photosensitive YBCO/AA solution is prepared using yttrium, barium, and copper acetates as starting materials, acrylic acid (AA) as chemical modifier, and methanol as solvent. AA can react with copper acetate to form the coordination chelate (Cu/AA) which can be stably existed in the YBCO/AA sol or gel films. The YBCO/AA gel film exhibits UV photosensitivity. Based on this photosensitivity of the YBCO gel films, the fine patterns of the YBCO gel films can be prepared using sol-gel method. The least line width of the fine patterning is about 9um.The photosensitive Y/BzAc, Cu/BzAc solutions are respectively prepared using yttium, and copper acetates as starting materials, benzylacetone (BzAcH) as chemical modifier, and methanol as solvent. BzAcH can react with yttium, and copper acetates to form the corresponding coordination chelates (Cu/BzAc,Y/BzAc) which can be stably existed in the subsequent sol or gel films. When the Y/BzAc, Cu/BzAc gel films are irradiated by the UV light, the metal (Y,Cu) coordination chelates are decomposed. The Y/BzAc and Cu/BzAc solutions exhibit good photosensitivity. Thus, the fine patterns of CuO, Y2O3 film can be prepared by UV exposure, rinsing process using organic solvent and the annealing treatment.Transparent, stable, and photosensitive YBCO/BzAc solution is prepared using yttium, barium, and copper acetates as starting materials, BzAcH as chemical modifier, and methanol as solvent. The metal chelates (Cu/BzAc,Y/BzAc) can be stably existed in the YBCO/BzAc sol. The YBCO/BzAc solution has a better photosensitivity than YBCO/AA solution. Using this photosensitivity, the fine patterns of YBCO/BzAc gel film can be prepared. The least line width of the fine patterning is about 3μm.The YBCO superconducting films on LaAlO3 substrate with high critical transition temperature of above 91K and sharp transition broad-width can be prepared using either YBCO/AA solution or YBCO/BzAc solution. Using photosensitive sol-gel method, the superconducting YBCO patterns can also be prepared. The patterned YBCO films also have high critical transition temperature of above 91K and sharp transition broad-width of about 1K. The patterned YBCO film also has a high critical current density of 106A/cm2.