A method for fabricating micro pipes on a semiconductor wafer or other substrate. According to the method of the invention, a base layer is initially deposited on the substrate and then etched to form a trench which exposes the surface of the substrate. Next, a PR (photoresist) layer of selected thickness is deposited over the base layer and the trench. Finally, in a curing step, the deposited photoresist is irradiated with ionizing radiation to cause outgassing of nitrogen gas from the photoresist layer, between the PR layer and the substrate. This step facilitates buckling of the PR layer into an arcuate bubble which defines the semispherical micro pipe structure.