Fabrication of three-dimensional crystalline microstructures by selective ion implantation and chemical etching

We present a new fabrication technique to produce three-dimensional (3D) microstructures on crystalline substrate using selective ion implantation and chemical etching. Localized lattice-damage layers at the specified depth beneath the substrate surface are formed by selective ion implantation. After etching out the partial surface regions and the buried lattice-damage layers by chemical etching, the 3D crystalline microstructures are produced. This technique is demonstrated on LiNbO₃ crystal to produce undercutting and free-standing microstructures, including microwire, microring, and microdisk. The measurement results of micro-Raman spectra show that the used fabrication process does not affect the original crystalline structure. The features of this technique include smooth structure surface, large undercutting range, and auto-etching stop. By using multiple implantations or repeating the proposed process several times, versatile 3D crystalline microstructures can be produced.