US 5,985,164 AGranted

Method for forming a filter

AssigneeThe Regents of the University of California

InventorsWen-Hua Chu, Mauro Ferrari

Life of this patent

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Abstract

Surface micromachining and bulk micromachining are employed for realizing a porous membrane with bulk support for a microparticle filter. The filter is manufactured by a process employing a thin film etch-stop, in which the bulk substrate is etched using a first etching process followed by etching of the etch stop and of material within pores of a filter layer using a second etching process. The filter is sufficiently sturdy to allow for easy handling. It may be used as a diffusion barrier and under high pressures. The disclosed fabrication method is simple, reliable, and integrated-circuit compatible, and thus amenable to mass production. Electronic circuitry may be integrated on the filter surface, as may be desired for several purposes, such as fluid characterization, filter self-cleaning, or charging of the filter surfaces. Methods are shown for the realization of biological containment capsules based on this microfilter.

Claims9

Dependent claims

A method for forming a filter with bulk support, comprising the steps of:

a. providing a bulk substrate, said bulk substrate being etchable using a first predetermined etching process;
b. forming a thin film etch-stop over a first area of a first surface of said bulk substrate, said etch-stop being etchable using a second predetermined etching process and said etch-stop not being etchable using said first predetermined etching process;
c. forming at least part of a filter structure over a second area of said first surface, said second area including at least a portion of said first area and said filter structure not being etchable by said second predetermined etching process, said etch-stop positioned between said filter structure and said bulk substrate, and said filter structure including a plurality of pores filled by a material etchable by said second predetermined etching process;
d. etching a portion of said bulk substrate underneath said etch-stop using said first predetermined etching process beginning at a second surface of said bulk substrate to expose an underside of said etch-stop;
and
e. etching at least a portion of said etch-stop and said material in said pores using said second predetermined etching process.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/950,952Filed 15 Oct 1997 · continuation
Priority: 7 Mar 1994
Granted: 16 Nov 1999
Term ends: Not estimatedThe source records don’t support an estimate.

Classification22 codes

B81C 1/00246
Integrating an electronic processing unit with a micromechanical structure: monolithic integration, i.e. micromechanical structure and electronic…
B01D 39/20
Other self-supporting filtering material ; Other filtering material: of inorganic material, e.g. asbestos paper, metallic filtering material of…
B01D 67/0058
By inducing porosity into non porous precursor membranes: by selective elimination of components, e.g. by leaching
B01D 67/0062
By elimination of segments of the precursor, e.g. nucleation-track membranes, lithography or laser methods: by micromachining techniques, e.g.…

Family

Serial207,459Parent of this continuation-in-part · filed 7 Mar 1994
Serial207,457Parent of this continuation-in-part · filed 7 Mar 1994
Serial254,330Parent of this continuation-in-part · filed 6 Jun 1994
Serial482,237Parent of this division · filed 7 Jun 1995
Serial649,998Parent of this continuation · filed 16 May 1996
US 5,770,076 AParent of this division
US 5,893,974 AParent of this continuation-in-part
US 5,660,680 AParent of this continuation-in-part
US 5,651,900 AParent of this continuation-in-part
US 5,985,164 AThis patent

From the US filing history. Foreign family members aren’t listed.