The fabrication of surface structures on silica includes techniques such as wet, dry , and vapor etching. Wafer-scale processing methods such as reactive ion etching and lithographically defined wet/dry etching can be adapted for silica. Recently, dry etching followed by HF-based wet etching is used to produce high-quality optical surfaces. Wet etching based on dilute ammonium fluoride solutions has also been used to tune the thickness of oriented mesoporous silica films. However, dry etching methods require expensive instruments and high-selectivity masking materials. Masking materials such as chromium (Cr) , photoresists, polysilicon, amorphous silicon, aluminum, silicon nitride, and chromium/gold (Cr/Au) have been reported for the etching of silica. These are typically patterned on the substrate using standard lithography techniques. Metal/polymeric nanoparticles (NPs) could replace these masking materials for the etching process. A combination of solid-state dewetting and annealing of thin metallic films on the silica surfaces resulted in the deposition of different metal NPs which acts as an etchant mask. Further, the plasma etching of NP-masked substrate resulted in the formation of silica nanostructures on the surface. The metal film thickness and dewetting conditions were used to tune the size and shape of the NPs which in turn influenced the optical reflection properties of the etched surface structures. This method required vacuum equipment for thin film deposition and high-temperature annealing for dewetting. Also, dewetting does not provide precise control over the size and shape of the NPs, which in turn can affect the features of the surface structures. In this context, the use of preformed NPs (with controlled size and shape) can replace the dewetting and annealing steps in the silica nanostructure fabrication process. Super hydrophilic transparent nanopillar structures on silica have been fabricated via the combination of nanosphere lithography and plasma etching which has been shown to prevent bacterial growth on the surfaces. Silicon nanostructures were fabricated through metal-assisted etching in which a thin layer of metal such as Au, Ag, Cu, and Pt, deposited on the Si surface, catalyzed the etching of Si in various mixtures of hydrofluoric acid (HF)/oxidant/solvent. Expensive requirements such as vacuum, plasma generation, or ion optics are inevitable in dry etching and sidewall damage is an undesirable effect associated with it. Therefore, wet chemical etching is considered a less expensive method to fabricate surface structures at higher etch rates on planes of different orientations. A thin monolayer of preformed metal NPs is suitable as an efficient etchant mask for the fabrication of silica structures via wet chemical etching using HF.