Cross‐sectional TEM analysis of fault and slip structures produced during etching processes for large‐scale superconducting‐tunnel‐junction array detectors

We proposed a model of fault and slip formation to explain the excessive increase of the leak current of Nb/Al superconducting tunnel junction detectors and the nano‐structural deformation. Observations of the cross‐sections at pinpoint places in the array detectors with transmission electron microscopy (TEM) support our model. The nano‐scale tectonism due to the relaxation of the residual stress in the sputtered films, which corresponds to a wafer bend motion at a few tens nm at 10 mm‐apart two points, generates the vertical fault in the Nb/Al film and the slip plane in the 1 nm‐thick AlOx tunneling layer. The slip in the AlOx layer can cause the leak current increase.