Nanomechanical test specimen preparation techniques by microfabrication and two‐photon lithography to avoid FIB induced Ga implantation damage
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- two-photon polymerization; nanocomposites; photolithography; microfabrication; reactive ion etching; Engineering
Traditional mechanical test specimen preparation methods require a subtractive approach to define the structure out of the bulk material. The most commonly used technology, focused ion beam patterning, leaves a modified specimen surface by gallium implantation resulting in for instance an altered grain structure. In this work, purely chemical approaches and an additive manufacturing technique are introduced to define test specimen.Compression pillars have been fabricated out of single crystal silicon and glass. The developed silicon process is crystalline orientation independent; consists of optical lithography, reactive ion etching via an alternating fluorine plasma and polymer passivation, surface oxidation and HF wet etching for sidewall planarization. High aspect ratio structures are achievable with a sub-50 nm surface roughness and parallel sidewalls.Glass pillar microfabrication requires a hard metallic mask due to the relatively low selectivity of any etchant plasma. Sputtered aluminum is patterned by photolithography and a chlorine based dry etch. The glass is reactively etched in a fluorine based plasma via this mask. The aluminum is then selectively removed by wet etching. The process has been demonstrated on a fused silica substrate with an average of 84º sidewall angle, although a wide variety of glasses may be used. Glass purity influences the sidewall angle.Please click Additional Files below to see the full abstract.