Sub-micron superconducting electronic devices may play a role in the realisation of proposed architectures for quantum computing and metrology. Further miniaturisation of superconducting electronics relies on the ability to fabricate the basic building block, the Josephson junction, on the scale of the superconducting coherence length, with sufficient accuracy that the junction characteristics may be controlled. Making use of focused ion beam technology to fabricate thin-film Nb microbridge devices, we examine the evolution of device characteristics with dimension, focusing on control of the critical current and suppression of superconductivity due to phase-slip behaviour.