Selective Material Removal for Nanostructure Formation

摘要

As the industry continues to fabricate structures with smaller dimensions―referred to as nanostructures―conventional wet etching can cause problems. The removal of silicon oxide to form freestanding nanostructures presents several challenges to process integration, including residue formation and stiction. Structure deformation and stiction are caused by the surface tension of liquids as they are removed from the surface. There are many methods being used to counteract these problems, such as the deposition of self-assembled monolay-ers (SAMs), the use of release agents, and the use of surfactants or a final dry in supercritical CO_2 (SCCO_2). These methods use liquid chemicals and water to condition the surfaces and make them less likely to bond. Another approach is the use of gaseous anhydrous HF (AHF), which removes the sacrificial oxide layer in a gaseous process and avoids the liquid phase altogehter.