Potential of micrometer-sized graphite as a catalyst for chemical etching of silicon

The chemical etching of silicon substrates, using graphite microparticles as a catalyst, was investigated. Graphite-coated silicon substrates were fabricated by drying a suspension of graphite particles onto substrates, which were then immersed in an etchant composed of HF and H2O2. The sections in the silicon surfaces covered with graphite particles sank down. The chemical etching proceeded only in the silicon beneath the graphite, similar to the conventional metal-assisted chemical etching that use noble metals as catalysts. The present graphite-assisted chemical etching provides a viable, low-cost micromachining process, which can replace conventional methods that employ expensive noble metal catalysts.