US 5,310,260 AGranted

Non-contact optical techniques for measuring surface conditions

AssigneeLuxtron Corporation

InventorsCharles W. Schietinger, Bruce E. Adams

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Abstract

Thermal, optical, physical and chemical characteristics of a substrate (11) surface are determined with non-contact optical techniques that include illuminating (23) the surface with radiation having a ripple intensity characteristic (51), and then measuring the combined intensities (53) of that radiation after modification by the substrate surface and radiation emitted from the surface. Precise determinations of emissivity, reflectivity, temperature, changing surface composition, the existence of any layer formed on the surface and its thickness are all possible from this measurement. They may be made in situ and substantially in real time, thus allowing the measurement to control (39, 41) various processes of treating a substrate surface. This has significant applicability to semiconductor wafer processing and metal processing.

Claims33

Dependent claims

A system adapted to measure a characteristic of a surface of an article, comprising:

a source of electromagnetic radiation that contains a time varying ripple component,
means for directing said source electromagnetic radiation against said article surface,
first and second photodetectors each characterized by generating an electrical signal proportional to a level of electromagnetic radiation incident upon it,
means positioned with respect to the article for carrying to the first photodetector both a portion of source electromagnetic radiation reflected from said article surface and electromagnetic radiation emitted by said article surface within a bandwidth of the source electromagnetic radiation,
means positioned with respect to the source for carrying to the second photodetector a portion of source electromagnetic radiation substantially without any radiation reflected or emitted from said article surface, said source radiation carrying means including an elongated light pipe having a solid end thereof with either a convex shape or roughened surface that is oriented to gather source radiation therethrough, and
means receiving and combining the electrical signals from the first and second photodetectors for determining characteristic of the surface.

3 more elements

A system adapted to measure a characteristic of a surface of an article, comprising:

a source of electromagnetic radiation that contains a time varying ripple component,
means for directing said source electromagnetic radiation against said article surface,
first and second photodetectors each characterized by generating an electrical signal proportional to a level of electromagnetic radiation incident upon it,
means positioned with respect to the article for carrying to the first photodetector both a portion of source electromagnetic radiation reflected from said article surface and electromagnetic radiation emitted by said article surface within a bandwidth of the source electromagnetic radiation,
means positioned with respect to the source for carrying to the second photodetector a portion of source electromagnetic radiation substantially without any radiation reflected or emitted from said article surface, said source radiation carrying means including an elongated light pipe and at least one lens having at least one convex surface directing radiation towards said elongated light pipe oriented to gather source radiation therethrough, and
means receiving and combining the electrical signals from the first and second photodetectors for determining the characteristic of the surface.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/999,278Filed 28 Dec 1992 · continuation in part
Priority: 10 Apr 1990
Granted: 10 May 1994
Term ends: Not estimatedThe source records don’t support an estimate.

Classification20 codes

G01B 11/06
For measuring length, width or thickness: for measuring thickness ; e.g. of sheet material
G01B 11/0658
Of coating: with measurement of emissivity or reradiation
G01J 5/0003
Radiation pyrometry, e.g. infrared or optical thermometry: for sensing the radiant heat transfer of samples, e.g. emittance meter
G01J 5/0007
For sensing the radiant heat transfer of samples, e.g. emittance meter: of wafers or semiconductor substrates, e.g. using Rapid Thermal Processing

Family

Serial507,605Parent of this continuation-in-part · filed 10 Apr 1990
Serial692,578Parent of this continuation-in-part · filed 19 Apr 1991
Serial943,927Parent of this continuation-in-part · filed 11 Sep 1992
US 5,154,512 AParent of this continuation-in-part
US 5,166,080 AParent of this continuation-in-part
US 5,310,260 AThis patent

From the US filing history. Foreign family members aren’t listed.