A novel electrochemical anodization cell

A novel design of an electrochemical anodization cell dedicated to the synthesis of mesoporous, single-crystalline silicon is presented. First and foremost, the design principle follows user safety since electrochemical etching of silicon requires highly hazardous electrolytes based on hydrofluoric (HF) acid. The novel cell design allows for safe electrolyte handling prior, during and post etching. A peristaltic pump with HF-resistant fluoroelastomer tubing transfers electrolytes between dedicated reservoirs and the anodization cell. Due to the flexibility of the cell operation, different processing conditions can be realized, providing a large parameter range for the attainable sample thickness, its porosity and the mean pore size. Rapid etching on the order of several minutes to synthesize micrometer-thick porous silicon epilayers on bulk silicon is possible, as well as long-time etching with continuous, controlled electrolyte flow for several days to prepare up to 1000 µm thick self-supporting porous silicon membranes. A highly adaptable, LabVIEW-based control software allows for user defined etching profiles.