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Browse Prior Art Database

Method of Producing Submicron Apertures with (Variable) Angles

IP.com Disclosure Number: IPCOM000108553D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

Bayer, T: AUTHOR [+4]

Abstract

The method described in this article permits the monitored production of micropipets with arbitrarily large aperture angles.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 63% of the total text.

Method of Producing Submicron Apertures with (Variable) Angles

       The method described in this article permits the
monitored production of micropipets with arbitrarily large aperture
angles.

      The initial substrate is a plane parallel silicon wafer which
is polished and (e.g., thermally) coated with SiO2 on either side.  A
circular aperture is etched into one side. By anisotropic wet
etching, a hole, limited by four 111-walls, is etched into the Si
wafer (Fig. 1).  Etching stops when these walls coincide (in
practice, the point of coincidence is frequently a blade, which does
not interfere with the application described in this article).

      The alternatively applicable dry etch process is favorably
carried out by RIE (reactive ion etching) (using HBr at a temperature
of ~ 20~ C) which allows varying the typical angle ranging from 70 to
90~.  (During anisotropic wet etching, the cone angle of the etched
hole is 70.6~.) Following this etch step, the SiO2 mask is removed
(as well as the SiO2 layer from the back of the wafer).  The
patterned front side is then coated with Si3N4 or SiC, using PECVD
(plasma enhanced chemical vapor deposition), up to a thickness of
about 1 to 2 mm (Fig. 2).

      This method is non-conformal, i.e., the layer thickness grown
on the substrate surface is larger than on the sidewalls of a hole.
For holes produced by wet anisotropic etching, the thickness of the
deposited layer decreases continuously towards the hole...