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Browse Prior Art Database

Damascene: Optimized Etch Stop Structure and Method

IP.com Disclosure Number: IPCOM000106596D
Original Publication Date: 1993-Nov-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Cronin, J: AUTHOR [+3]

Abstract

Disclosed is a method for optimizing etch stop structures in Damascene processed on-chip wiring structures. Etchstops are typically used to control trench etch in this process but the resulting structure has etchstop material (usually a high &epsilon. material such as silicon nitride) remaining between the lines (Figure). This material significantly impacts line to line capacitance in these structures. This impact is mitigated by eliminating the etch stop material remaining between the lines through the use of an etch stop patterning step.

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Damascene: Optimized Etch Stop Structure and Method

      Disclosed is a method for optimizing etch stop structures in
Damascene processed on-chip wiring structures.  Etchstops are
typically used to control trench etch in this process but the
resulting structure has etchstop material (usually a high &epsilon.
material such as silicon nitride) remaining between the lines
(Figure).  This material significantly impacts line to line
capacitance in these structures.  This impact is mitigated by
eliminating the etch stop material remaining between the lines
through the use of an etch stop patterning step.

      The basic structure arising from the Damascene process is shown
in the Figure with the standard etchstop shown as indicated.  For the
layer shown as the modified etchstop we include an extra masking
level following the initial etchstop deposition.  This mask is
fabricated as the inverse of the next mask level (the one which will
define the shapes in the level of insulator being deposited) with a
slight positive bias to allow for misregistration.  In this way, the
etchstop only remains in the regions where it will actually be
needed.  The extra mask requires no additional design effort as it is
automatically created from the original design data.  The process
itself is not particularly critical involving only reasonable care in
alignment.  The result will vary depending the relative dielectric
constants of the primary insulator and the etchstop material an...