Method for preparing superconductive nanometer device by negative electron beam resist exposure process

Abstract

The invention discloses a method for preparing a superconductive nanometer device by a negative electron beam resist exposure process. The method mainly comprises the following steps of: spinning a hydrogen silsesquioxane (HSQ) resist on a superconductive thin film; pre-drying; designing an exposure graph; exposing by two steps; developing; fixing; and etching. By using the method, the superconductive nanometer device which is stable in performance and uniform in line width and has the minimum line width of 15 nm can be prepared. Residues do not exist in an electrode region after the etching step is performed by setting an exposure amount in different regions and changing the thickness of an exposure product in the corresponding region, so that electrical measurement is facilitated. HSQ has high anti-etching performance and is suitable to serve as an etching mask of a hard superconductive metal material, so that the etching selection ratio can be increased. An electrode and the device are obtained through one-time etching; no contact potential difference exists between the electrode and the device; and the success rate of the device is high. Furthermore, a plurality of independent micro electric bridges are exposed on the same thin film, so that the efficiency of integrating and measuring the electric bridges can be improved, and the material utilization rate is increased; and the superconductive nanometer device has great significance for research on nanometer structures made of rare materials.

Description

technical field [0001] The invention belongs to the technical field of micro-nano processing, in particular to a method for preparing a superconducting nano-device by a negative electron beam resist exposure process. Background technique [0002] With the development of micro-nano-fabrication technology, the research on superconducting materials at the micro-scale has attracted extensive attention. Novel superconducting nanodevices continue to emerge, such as nano-superconducting quantum interference devices (nano-SQUID), superconducting nanowire single-photon detectors (SNSPD), Josephson junctions (Josephsonjunctions), superconducting qubits (Quantum bits) Wait. In the manufacturing process of superconducting devices, it is required not only the small size, but also reduce the influence of micro-nano processing on the superconducting characteristics as much as possible. This is the key to obtaining high-performance devices, and it is also a difficult point. [0003] In th...

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Problems solved by technology

For hard metal and ceramic high-temperature superconducting thin films, it is difficult to obtain high-quality samples by exfoliation and desorption

Positive photoresist PMMA, ZEP520, etc. are also used as etching masks in the research, but it will be difficult to make fine lines and dense patterns; at the same time, this method generally needs to make measurement bridges through ultraviolet exposure first, and then through electron beam exposure. Complex process for making nanostructures

In addition, in literature reports, there is also a method of directly processing superconducting devices by using maskless focused ion beam (FIB), but the disadvantage of this method is that it will bring Ga + Contamination of ions, and direct bombardment of ion beams can also seriously degrade superconducting properties

[0005] However, HSQ also has shortcomings: First, its exposure product SiO x Insoluble in organic solvents, which makes it difficult to remove the glue after etching

In this method, due to the adhesion of the deposition electrode, contamination of the interface, contact potential difference, etc., the ohmic contact performance between the electrode and the device is poor, and the success rate of the device is low.

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