One challenge in fabricating submicron ridge waveguide photonic devices is the formation of metal contacts and passivation. In this article, the authors report a self-aligned metal-contact and passivation technique suitable for submicron to nanoscale ridge waveguide device fabrication. The technique uses two different dielectric materials, e.g., SiO2 and Si3N4, with a different wet-etching selectivity. The first dielectric material (SiO2) acts as the etching mask and the second dielectric material (Si3N4) with a much lower etching rate acts as the passivation film. An undercut is formed in the semiconductor below the SiO2 mask by a wet-etching process. The semiconductor surface on top of the ridge waveguide will be fully exposed to metal contact by the lift-off process. A 0.7-μm-wide InGaAsP∕InP ridge waveguide laser was fabricated using the technique proposed. Mode simulation showed that the 0.7-μm-wide and 1.2-μm-deep ridge waveguide in the InGaAsP∕InP laser structure has good optical field confinement. Lasing is obtained on the 0.7-μm-wide ridge waveguide laser under current injection. An ∼240nm ridge waveguide is also demonstrated as an example of the technology for deep-submicron waveguide structure fabrication. The whole process is completely compatible with the existing compound semiconductor process and can be extended to fabricating other submicron to nanoscale devices.