Method of producing a sheet comprising through pores and the application thereof in the production of micronic and submicronic filters

Abstract

The method comprises the following steps: preparing a sheet having thickness of 5 mum to a few tens of micrometers, suitable for being etched by a lithographic operation; making a mask on a face of the sheet, the mask presenting etching selectivity S of at least 5; depositing a layer of photosensitive resin on the mask; making through holes in the layer of resin by photolithography; etching through the mask via the pores in the layer of resin; and anisotropically etching through the sheet from the pores in the mask in order to make pores in the sheet having an aspect ratio greater than 5. The invention is applicable to fabricating micron and sub-micron filters.

Description

technical field [0001] The present invention relates to a method for the production of perforated foils (sheets) and perforated membranes for the production of micron and submicron filters with calibrated (scaled) cylindrical pores, to said foils thus obtained, membranes and filters. Background technique [0002] Said filters are used in a very wide range of technical fields, such as air filtration, more generally gas filtration, liquid effluent filtration, in particular tangential filtration, powder separation or powder size classification filtration. [0003] Such filters are used in the agro-food processing industry, in the pharmaceutical industry, in the treatment of gaseous or liquid emissions, in the production and supply of dust-free pure gases, and more generally in all industrial fields requiring separation and filtration steps There are applications. [0004] Fabrication of microporous grids (or grids of holes) in dielectric materials, composite materials (photon...

AI Technical Summary

Problems solved by technology

Unfortunately, the technique has many drawbacks and limitations, namely: i) The silicon wafer needs to be thinned (typically 500 microns to a few tenths of a micron) in order to avoid excessive head loss for flux (flow) through the filter ; ii) the method is limited to the largest wafer size available; iii) excessive raw material costs (thick single crystals, which are not compatible with filters used in industrial filtration); iv) use of brittle materials for fabrication brittleness of the filter (shock, stress); v) impossibility to shape the resulting filter (tube, closure); vi) unstable corrosion resistance (corrosion by strong alkalis and certain acid solutions)

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