Method and apparatus for determining lithographic quality of a structure

Patent metadata

Field	Value
Publication number	US-9518936-B2
Application number	US-201314648457-A
Country	US
Kind code	B2
Filing date	Oct 30, 2013
Priority date	Nov 30, 2012
Publication date	Dec 13, 2016
Grant date	Dec 13, 2016

Abstract

Method for determining lithographic quality of a structure produced by a lithographic process using a periodic pattern, such as a grating, detects lithographic process window edges and optimum process conditions. Method steps are: 602 : printing a structure using a lithographic process using a grating pattern; 604 : selecting a first characteristic, such as a polarization direction, for the illumination; 606 : illuminating the structure with incident radiation with first characteristic 608 : detecting scattered radiation; 610 : selecting a second characteristic, such as a different polarization direction, for the illumination; 612 : illuminating the structure with incident radiation with the second characteristic; 614 : detecting scattered radiation; 616 : rotating one or more angularly resolved spectrum to line up the polarizations, thus correcting for different orientations of the polarizations; 618 : determining a difference between the measured angularly resolved spectra; and 620 : determining a value of lithographic quality of the structure using the determined difference.

First claim

The invention claimed is:

1. A method comprising:
illuminating a structure with a beam;
measuring intensity of non-zeroth order radiation based on the beam being scattered by the structure;
comparing the measured intensity of non-zeroth order radiation and a value of intensity corresponding to an absence of non-zeroth order radiation; and
determining a parameter of the structure based on the comparison.

2. The method of claim 1 , wherein the beam is polarized.

3. An apparatus comprising:
an illumination system configured to illuminate a structure with a beam;
a detection system configured to measure intensity of the non-zeroth order radiation based on the beam being scattered by the structure; and
a processor configured to:
compare the measured intensity of non-zeroth order radiation and a value of intensity corresponding to an absence of non-zeroth order radiation, and:
determine a parameter of the structure based on the comparison.

4. The apparatus of claim 3 , wherein:
the processor is further configured to perform the comparison by determining a difference between the measured intensity of non-zeroth order radiation and the value of intensity corresponding to an absence of non-zeroth order radiation.

5. The apparatus of claim 3 , wherein:
the illumination system is further configured to illuminate a plurality of structures;
the detection system is further configured to measure intensities based on the beams being scattered by the plurality of structures; and
the processor is further configured to determine a process window edge of a lithographic process used to produce the plurality of the structures based on the parameters.

6. The apparatus of claim 3 , wherein:
the illumination system is further configured to illuminate a plurality of structures;
the detection system is further configured to measure intensities based on the beams being scattered by the plurality of structures; and
the processor is further configured to determine an optimum process condition of a lithographic process used to produce the plurality of the structures based on the parameters.

Assignees

• Asml Netherlands Bv

Inventors

• Grootjans Willem Jan
• Megens Henricus Johannes Lambertus
• Krist Jouke
• Garcia Granda Miguel
• Xu Lu

Classifications

• G03F7/70641

  Focus · CPC title

• G03F7/70625

  Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness · CPC title

• G03F7/70558

  Dose control, i.e. achievement of a desired dose · CPC title

• G01N21/95607 Primary

  using a comparative method · CPC title

• G01N2021/4792

  Polarisation of scatter light · CPC title