Shear band formation is critical in understanding plasticity in non-crystalline solids such as metallic glasses. The shear bands in metallic glasses initiate from generally multiple soft spots, which interact and compete for growth. Eventually one shear band becomes dominant, growing rapidly driven by the elastic energy release of the rest of the sample. In this talk, however, we will focus on isolated, steady-state shear band close to zero-width, in a tip wear system (a flat amorphous tip sliding against a rigid slider). Here, the shear band locates at the interface (highest plastic strain rate is from the moving debris; the strain rate quickly decreases to zero away from the interface). Such steady-state shear bands enable position dependent effective temperature measurement of the shear band. We show that the effective temperature, characterizing the mechanical agitation from the slider, governs both the debris formation and the shear band formation. Furthermore, the plastic activities of the shear band can be characterized by the debris clusters. We show that large fractal clusters emerge as the contact stress approaches a critical value corresponding to global plasticity.