  We present a structure and a fabrication method for superconducting tunnel
junctions down to the dimensions of 200 nm using i-line UV lithography. The key
element is a side-wall-passivating spacer structure (SWAPS) which is shaped for
smooth crossline contacting and low parasitic capacitance. The SWAPS structure
enables formation of junctions with dimensions at or below the
lithography-limited linewidth. An additional benefit is avoiding the excessive
use of amorphous dielectric materials which is favorable in sub-Kelvin
microwave applications often plagued by nonlinear and lossy dielectrics. We
apply the structure to niobium trilayer junctions, and provide characterization
results yielding evidence on wafer-scale scalability, and critical current
density tuning in the range of 0.1 -- 3.0 kA/cm$^2$. We discuss the
applicability of the junction process in the context of different applications,
such as, SQUID magnetometers and Josephson parametric amplifiers.
