Browse Prior Art Database

Method to Control Depth of Etching

IP.com Disclosure Number: IPCOM000109170D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 2 page(s) / 68K

Publishing Venue

IBM

Related People

Cronin, JE: AUTHOR [+2]

Abstract

To assist in creating controlled depth channels and/or holes (features) in a substrate, an etch stop layer and a controlled thickness of a material having a known etch rate ratio (ERR) relative to the substrate material are first deposited on the substrate. The etch stop material provides superior end point detection as well as stopping etching and may be completely removed during subsequent processing. This technique is especially useful where etch stop materials cannot become a permanent part of a product or where choice of etch stop material is limited by product sensitivity. To best illustrate benefits provided by the method, a dual Damascene process is described.

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Method to Control Depth of Etching

       To assist in creating controlled depth channels and/or
holes (features) in a substrate, an etch stop layer and a controlled
thickness of a material having a known etch rate ratio (ERR) relative
to the substrate material are first deposited on the substrate.  The
etch stop material provides superior end point detection as well as
stopping etching and may be completely removed during subsequent
processing.  This technique is especially useful where etch stop
materials cannot become a permanent part of a product or where choice
of etch stop material is limited by product sensitivity.  To best
illustrate benefits provided by the method, a dual Damascene process
is described.

      Referring to Fig. 1, substrate 2 (silicon dioxide, for
instance) is to have a wiring channel etched to a controlled depth
and a connecting via hole etched completely through it to an
underlying contact (not shown) which provides an etch stop at that
point.  An etch stop layer 4, e.g., aluminum, is deposited on
substrate 2 and a layer 6 of thickness H is deposited.  Layer 6 may
be of any material having a known ERR with respect to substrate
material 2.  In this illustration, layer 6 is assumed to be the same
material as substrate 2 and has the same etch rate (ERR = 1).
Positive photoresist layer 8 is deposited, exposed, and developed to
create via hole region V and hardened by any of several methods to
resist change during deposition, exposure,...