Formation of fine near-field scanning optical microscopy tips. Part I. By static and dynamic chemical etching

The probe tip is the key component in scanning probe microscopes and their applications in the nanoscale imaging and nanofabrication. In this work, we have investigated the formation of near-field scanning optical microscopy probe tips from optical fiber by chemical etching. Static and dynamic etchings and their combinations are studied. The etching process is optimized, and tips with short tapers, small apertures (about 50 nm) and large aperture cone angles (40°) are successfully obtained. Multiple-tapered tips are also fabricated by using different dynamic regimes. It is found that the taper profiles are determined by the nonlinear dynamic evolution of the meniscus of the etchant near the fiber.