Feature

Laser Chemical Etching of Semiconductors

Carol I. H. Ashby

Many of today's important technologies require selective removal of small regions of a thin film to produce a particular pattern. Laser-driven chemical reactions have been extensively studied as alternatives to current ion-beam-based etching processes, such as ion-beam milling and reactive ion etching (RIE). The attraction of photon-based processes lies in their ability to selectively etch very small features with little or no substrate damage using a range of reactants, temperatures, and pressures. There are three general reaction classes: thermal chemical reactions, photochemical reactant generation, and carrier-driven reactions. The most appropriate type to use depends on the specific application. Although most research has employed lasers, one should always bear in mind that there is nothing magic about using a laser except when extremely monochromatic or highly coherent light is required. For many applications, high-intensity lamps might be a better light source.