We present a technical processing to fabricate substrates (fused silica) for 3-D photonic bandgap material. The potential surface was modified to improve the colloidal method for nanoparticles assembly. This method allows orientating the growth of the colloidal crystals in a specific way; the crystalline plans growth is parallel to the surface of the substrate, and we can eliminate stacking defects and polycrystallinity. The substrate is obtained with ions beam engraving, according to the following process:
A layer of photoresist is deposited on the substrate; we write two identical holographic gratings on the photoresist with 90° angle;
After the development of photoresist, we obtain a profile which corresponds to one of the crystalline plans of the face centered cubic lattice;
This profile will be transferred on the substrate by RIE (reactive ion etching).
This substrate has many advantages: it is reusable because it is easily cleaned with solvents like acetone; the same substrate will be easy to use in order to make several growth tests and to optimize physicochemical parameters during artificial opals fabrication.