Browse Prior Art Database

Precise Diameter Measurement of Contact Holes and Inspection of Resist Residuals

IP.com Disclosure Number: IPCOM000111476D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Graulich, M: AUTHOR [+3]

Abstract

The field in future semiconductor manufacturing can be improved, if very precise and sensitive measurements and inspection tools are developed to characterize the optical lithography process, so that a go or rework decision is possible. The most difficult process in lithography is the layer with contact holes. They are the smallest dimension in lithography. The diameter of the contact hole has to be precisely measured, and the bottom of the contact hole has to be free of resist residuals. The optical measurement systems on the market suffer from thin film interferences and low resolution.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 55% of the total text.

Precise Diameter Measurement of Contact Holes and Inspection of Resist
Residuals

      The field in future semiconductor manufacturing can be
improved, if very precise and sensitive measurements and inspection
tools are developed to characterize the optical lithography process,
so that a go or rework decision is possible.  The most difficult
process in lithography is the layer with contact holes.  They are the
smallest dimension in lithography.  The diameter of the contact hole
has to be precisely measured, and the bottom of the contact hole has
to be free of resist residuals.  The optical measurement systems on
the market suffer from thin film interferences and low resolution.

      It is proposed to use a confocal laser scanning microscope to
overcome these problems.  The highest possible optical resolution is
achieved in incoherent confocal systems.  In an incoherent system
there exist no interferences, so the measurements will be accurate.
The incoherence should be established by fluorescent dyes, added to
the resist.

      The technical problems are now the high demand on measurement
precision and the high sensitivity to detect resist residuals.  To
establish high precision, a two-dimensional gauge with nanometer
increments (e.g., interferometer) is conventionally used.  It is
proposed not to use an expensive gauge; the measurement precision
should be established by self-calibration.  The distance of the
contact holes should be used as a referenc...