Macroporous silicon has gained interest in research for many applications which have a demand for mechanical and chemical stability as well as a high order of the pores. The membranes are manufactured from single crystal n-doped silicon wafers.
The pore diameters can differ from 1 µm up to 8 µm. The standard deviation of pore diameter and interpore distance is lower than 10 %. Because of the lithographic pre-structuring technique macroporous silicon with its high ordered structure represents an ideal 2-D photonic crystal (PC) exhibiting novel properties for the propagation of infrared light within the pores.
Because of the above mentioned unique properties macro porous silicon can be used in a wide range of applications, such as filtration, as platform for multi-functional flow-through sensors and diagnostics, as electrode material (e.g. fuel cells) or micro reactors, and especially as templates for the fabrication of micro scale composites, such as tubes or wires by electrochemical deposition or by using polymer melts.
Our MakroPor membranes feature perfectly ordered pores with an unique pore diameter which stays constant through the complete length of the pores. The pores are arranged evenly over the complete wafer size in an exact trigonal or cubic array due to the prestructuring step. By applying an additional anisotropic etching the round pores can be also widened to square-shaped pores.
Pore diameter: 1 µm (pitch 1.5 µm; trigonal order, round pores); lift-off process
Pore diameter: 2.5 µm (pitch 4.2 µm; trigonal order, round pores); lift-off process
Pore diameter: 5 µm (pitch 12 µm; cubic order, round pores); flat backside
Pore diameter: 8 µm (pitch 1.5 µm; cubic order, square shaped pores), flat backside
Lift-off process: process to produce thin membranes; the pores are widended at the bottom to such an extent that the pore wall to the neighboring pore dissolves and hence there is no connection to the bulk material as well; this results in a peak structure on the bottom surface in contrast to a smooth top surface of the membrane.