US 4,893,932 AGranted

Surface analysis system and method

AssigneeParticle Measuring Systems, Inc.

InventorRobert G. Knollenberg

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Abstract

A surface analysis system and method are disclosed for determining particle contamination and/or defects on or below a surface of material. Laser beams having different polarizations are directed to the surface to be analyzed and light scattered from particle contamination and/or defects on or below the surface is collected and detected to provide electrical signals representative thereof. The electrical signals are then processed to provide an output indicative of sensed contamination and/or defects. In the embodiment particularly shown and described, a pair of polarized laser beams, one of which is a "P" polarized laser beam and the other of which is a "S" polarized laser beam, are separately directed to a monitoring region so that the beams impinge at a common point on the surface to be analyzed. The scattered light is then collected and split into two components depending upon whether scattered from the "P" polarized laser beam or the "S" polarized laser beam and each component is separately detected, after which the electrical outputs are processed to provide the desired indication.

Claims21

Dependent claims

A surface analysis system, comprising:

beam generating means for providing first and second illuminating beams having predetermined different polarizations;
beam directing means for directing said beams to a monitoring region;
support means for supporting a material having a surface to be analyzed for the presence of submicron particles on and below said surface with said surface being positioned at said monitoring region so that said beams impinge on said surface in a manner such that light is scattered by contamination and defects on and below said surface due to the presence of said submicron particles;
collecting means for collecting intensities of said light scattered by said contamination and defects on and below said surface;
separating means for separating said intensities of scattered light collected by said collecting means into first and second components with said first component including intensities of scattered light from said first beam and said second component including intensities of scattered light from said second beam;
first and second detecting means, said first detecting means receiving said first component of scattered light intensities from said separating means and said second detecting means receiving said second component of scattered light intensities from said separating means, said first and second detecting means, responsive to receipt of said components of scattered light intensities, providing separate outputs indicative thereof;
and
processing means for receiving said outputs from said detecting means and utilizing the same to provide an output indicative of said submicron particles on and below said surface.

5 more elements

A surface analysis system, comprising:

support means for supporting a material having a surface to be analyzed by light scattering for the presence of submicron particles on and below said surface with said surface being maintained at a monitoring region in a manner such that light is scattered by contamination and defects on and below said surface due to the presence of said submicron particles;
first laser means providing a "P" polarized laser beam;
second laser means providing an "S" polarized laser beam;
first directing means for directing said "P" polarized laser beam to said monitoring region at a predetermined incidence angle;
second directing means for directing said "S" polarized laser beam to said monitoring region at said predetermined incidence angle so that "P" polarized laser beam and said "S" polarized laser beam impinge on said surface at substantially a common point;
collecting means including a lens set for commonly collecting said light scattered from on and below said surface due to the presence of submicron particles with respect to both said "P" polarized laser beam and said "S" polarized laser beam;
polarizing beam splitting means for separating said light scattered from said "P" polarized laser beam and said "S" polarized laser beam;
first detecting means for receiving said light scattered from said "P" polarized laser beam and providing an electrical signal indicative thereof;
second detecting means for receiving said light scattered from said "S" polarized laser beam and providing electrical signal indicative thereof;
and
signal processing means connected to receive the outputs from said first and second detecting means and responsive thereto providing an output indicative of submicron particles on and below said surface to thereby indicate at least one of contamination and defects on and below said surface of said material.

8 more elements

A method for analyzing the surface of an element, said method comprising:

providing a first polarized beam;
providing a second polarized beam having a polarization different from said first beam;
directing said first and second beams to a monitoring region at substantially identical incidence angles;
providing a material at said monitoring region with said material having a surface to be analyzed by light scattering for the presence of submicron particles on and below said surface with said surface being positioned at said monitoring region so that said beams impinge on said surface in a manner such that light is scattered by contamination and defects on and below said surface due to the presence of said submicron particles;
collecting intensities of said light from said first and second beams that have been scattered by contamination and defects on and below said surface of said material due to the presence of said submicron particles;
separating said collected light intensities scattered from said first and second beams;
detecting said separated and collected light intensities scattered from first and second beams to form electrical signals indicative thereof;
and
processing said electrical signals to provide an indication of submicron particles to thereby indicate at least one of contamination and defects on and below said surface of said material.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/262,216Filed 21 Oct 1988 · continuation
Priority: 2 May 1986
Granted: 16 Jan 1990
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G01N 21/9501
Characterised by the material or shape of the object to be examined: semiconductor wafers
G01N 21/21
Systems in which incident light is modified in accordance with the properties of the material investigated: polarisation-affecting properties
G01N 21/94
Investigating the presence of flaws or contamination: investigating contamination, e.g. dust
G01N 21/9505
Semiconductor wafers: wafer internal defects, e.g. microcracks