Three-dimensional structuring of sapphire by sequential He+ ion-beam implantation and wet chemical etching

We present a method for the selective two- and three-dimensional patterning of sapphire using light ion-beam implantation to generate severe lattice damage to depths exceeding 1 μm and subsequent selective wet chemical etching of the damaged regions by hot H₃PO₄. C-cut sapphire crystals were implanted through contact masks using ion fluences of 1×10¹⁶ to 5×10¹⁷ He⁺/cm² and energies up to 400 keV. The etching process is characterized by a high selectivity and a rate of approximately 19 nm/min. Whereas an implantation that produces a continuously damaged pathway results in complete etching from the surface, sole in-depth implantation using only high-energy ions leads to under-etching of the crystalline surface layer. By a combination of these processes we have fabricated three-dimensional structures such as channels and bridges in sapphire. Received: 14 October 2002 / Accepted: 15 October 2002 / Published online: 26 February 2003 RID="*" ID="*"Corresponding author. Fax +41-21/693-3701, E-mail: aurelian.crunteanustanescu@epfl.ch