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Method for forming a filter

  • US 5,985,164 A
  • Filed: 10/15/1997
  • Issued: 11/16/1999
  • Est. Priority Date: 03/07/1994
  • Status: Expired due to Term
First Claim
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1. 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.

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