In the related art, the release accuracy of the bridge brace is increased by improving the etching process. In the improved etching process, the effect of releasing the bridge brace is improved using methods such as changing the composition of an etching gas, adjusting an etching time, and detecting the composition of an exhaust gas after etching. However, it is still difficult to effectively remove a bridge brace material deep in a bridge hole. In conclusion, disadvantages are as follows:

1. Generally, an additional gas path needs to be added to equipment to modify the composition of the etching gas, which involves the difficulty of equipment modification.

2. An additional detection device is required for detecting the composition of the exhaust gas, which increases costs.

3. The method of adjusting the etching time by detecting the composition of the exhaust gas may prolong the etching time, which has relatively large impact on the performance of the junction device on a superconducting chip.

4. The modification of the composition of the etching gas involves inflammable and explosive gases such as methanol, which poses hidden dangers to the safety of the production workshop or laboratory.

In addition, a fully-enclosed air bridge without an opening is likely to cause unevenness of the deck such as bumps, dents, undulations, and the approach bridge is also likely to break.