Formation of multilayer structures with integrated membranes based on porous silicon

Multilayer integrated porous membranes in a monolithic frame were obtained. Porous membranes consist of macroporous silicon with pore diameters of up to 10 $\mu$m and channel silicon with channel diameters from 100 to 300 nm. A laboratory technology is proposed to formation of macroporous/channel silicon two-layer structures using high-resistance $n$-Si substrates (1 $\Omega$ cm). The mechanism of pore formation is discussed and how this mechanism affects the morphology of porous layers when formic acid and ammonium hydroxide are used as electrolytes.