Browse Prior Art Database

Automated Multiple Angle of Incidence Ellipsometer System

IP.com Disclosure Number: IPCOM000099686D
Original Publication Date: 1990-Feb-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 8 page(s) / 309K

Publishing Venue

IBM

Related People

Manthei, LW: AUTHOR [+5]

Abstract

A technique is described whereby an automated multiple angle of incidence ellipsometer system provides non-destructive testing of thin films, as used in the production of semiconductor wafers. The system provides automatic, accurate measurements of multilayer films with a minimum of operator interaction. The various elements of the system are described which enable measurements to be made at different angles on a wafer.

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Automated Multiple Angle of Incidence Ellipsometer System

       A technique is described whereby an automated multiple
angle of incidence ellipsometer system provides non-destructive
testing of thin films, as used in the production of semiconductor
wafers.  The system provides automatic, accurate measurements of
multilayer films with a minimum of operator interaction.  The various
elements of the system are described which enable measurements to be
made at different angles on a wafer.

      The system is designed to be used in wafer measurements after
each oxidation and low pressure chemical vaporization deposition
process.  It is composed of a commercial ellipsometer repackaged into
a specifically designed multiple angle of incidence drive and support
unit.  The ellipsometer includes a laser, polarizer, analyzer,
detector and a processing board.  Incorporated is a microscope with
an autofocus unit and a high resolution color video system. So as to
measure the angle of incidence with respect to the local tilt of the
wafer surface, a relative angle measurement system consisting of a
laser source and quad detector is used.  Additional actuating and
sensing components are required to move and control components, such
as the polarizer, shutters and switches.

      The entire ellipsometer configuration is mounted on a vibration
isolation table.  An XYZ and theta stage (not shown) is used to
position and orient the wafer chuck. Wafer load and unloading is
accomplished by an automatic wafer handler (not shown).  The system
is controlled by means of an industrial computer.

      Angle of incidence (AOI) assembly 1, as shown in Fig. 1A,
consists of the ellipsometer components: laser/polarizer assembly 2
and  analyzer/detector assembly 3, as shown in Fig. 2, adjustable
mounting brackets (not shown) and electronic control unit 4, as shown
in Fig.  1B.

      Laser/polarizer assembly 2 and analyzer/detector assembly 3, as
shown in Fig. 2, are configured to travel on 180-degree circular arc
mechanism 5, positioned over wafer chuck 6.  The center of the circle
defined by the arc is at the measurement site on the surface of the
wafer. Laser/polarizer assembly 2 and analyzer/detector assembly 3
travel on the outer radius of the arc with the optical axis of each
directed radially inward and intersecting at the center of the arc
(measurement site).

      Laser/polarizer assembly 2 travels on the left half of the arc
with its position from the wafer normal defining the angle of
incidence. Analyzer/detector assembly 3 travels on the right half of
the arc with its position from the wafer normal defining the
corresponding and equal angle of reflection.  This configuration
allows laser/polarizer assembly 2 and analyzer/detector assembly 3 to
move independent of each other, allowing for increasing flexibility
in system alignment and operation.

      Arc mechanism 5 has a precision ground radius of twelve inches
and a t...