Browse Prior Art Database

Endpoint Technique for Processing Metal Damascene Structures

IP.com Disclosure Number: IPCOM000113960D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Kaufman, F: AUTHOR [+3]

Abstract

This invention describes the use of commercially available reflectivity thickness measurement tools in providing an endpoint determination method for metal processed structures. In practice the method involves a repetitive process-measure sequence until the measurement shows the wafer is completely processed; (all metal removed from field). Data on actual processed wafers are shown in Figs. 1 and 2 to illustrate use of the method.

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Endpoint Technique for Processing Metal Damascene Structures

      This invention describes the use of commercially available
reflectivity thickness measurement tools in providing an endpoint
determination method for metal processed structures.  In practice the
method involves a repetitive process-measure sequence until the
measurement shows the wafer is completely processed; (all metal
removed from field).  Data on actual processed wafers are shown in
Figs. 1 and 2 to illustrate use of the method.

      Fig. 1 shows reflectivity measurements performed on patterned
wafers as a function of endpoint in arbitrary units.  To get the
number of open sites, the reflectivity tool need merely be used in a
mode where field sites still covered with conductor or liner metal
register as unmeasureable sites.  At endpoint all metal in the field
has been removed and the number of cleared sites changes no further
and is equal to the total number of sites being measured.  Once
endpoint has been reached, the extent beyond endpoint can be
determined from a calibration curve of the type shown in Fig. 2.
This Figure shows that the net insulator thickness I varies as a
linear function of the extent beyond endpoint.  Net thickness is
given by (field thickness-pad adjacent thickness), where the latter
is measured in the insulator but adjacent to any metal pad feature.