In-situ source metrology instrument and method of use

• US 20030007143A1
• Filed: 10/09/2001
• Published: 01/09/2003
• Est. Priority Date: 02/10/1999
• Status: Active Grant

• Current Assignee: Litel Instruments Incorporated
• Original Assignee: Litel Instruments Incorporated
• Inventors: Smith, Adlai H., McArthur, Bruce B.
• Granted Patent: US 6,741,338 B2
• Time in Patent Office: Days
• US Class Current: 356/121
• CPC Class Codes: G01J 9/00 Measuring optical phase difference devices or arrangements for controlling the phase of light beams G02F1/01; Determining degree of coherence; Measuring optical wavelength spectrometry G01J3/00
• CPC Class Codes: G01M 11/0207 Details of measuring devices
• CPC Class Codes: G01M 11/0264 by using targets or reference patterns
• CPC Class Codes: G03F 7/70591 Testing optical components
• CPC Class Codes: G03F 7/706 Aberration measurement

Abstract

A process of measuring the radiant intensity profile of an effective source of a projection image system that has an effective source, an object plane, an imaging objective, an exit pupil, and an image plane. The improved process consists of selecting at least one field point and a corresponding aperture plane aperture and projecting a plurality of images of the selected field point through the corresponding selected aperture plane aperture at a plurality of various intensities of the effective source. By analyzing the recorded images of the effective source at various intensities it is possible to determine a radiant intensity profile of the image source at the selected field point.

Claims

1. A process of measuring the radiant intensity profile of an effective source of an projection image system having an effective source, an object plane, an imaging objective, an exit pupil, and an image plane, the process comprising the steps of:

providing an array of field points on an object plane of the projection imaging system;

providing a corresponding array of aperture plane apertures displaced from the object plane a sufficient distance to image the effective source, the array of corresponding object plane apertures corresponding to the field points on the object plane;

selecting at least one field point and a corresponding aperture plane aperture;

projecting a plurality of images of the selected field point through the corresponding selected aperture plane aperture at a plurality of various intensities of the effective source to produce at the image plane a corresponding plurality of images of the effective source image at the selected field point;

recording the plurality of effective source images of the selected field points on recording media at the image plane to produce recorded images for each of the plurality of various intensities; and

,

analyzing the recorded images of the effective source on the media for the selected field point and aperture plane aperture to determine a radiant intensity profile of the image source at the selected field point.

2. The process of measuring the radiant intensity profile of an effective source of an projection image system according to claim 1 and comprising the further steps of:

selecting a plurality of field points and a corresponding aperture plane apertures; and

,

for each selected field point repeating the projecting, recording and analyzing steps.

3. The process of measuring the radiant intensity profile of an effective source of an projection image system according to claim 1 and comprising the further steps of:

the projecting a plurality of images step includes projecting frame patterns.

4. The process of measuring the radiant intensity profile of an effective source of an projection image system according to claim 1 and comprising the further steps of:

the projecting a plurality of images step includes projecting a unique number designating the field point.

5. The process of measuring the radiant intensity profile of an effective source of an projection image system according to claim 1 and comprising the further steps of:

the projecting a plurality of images of the selected field point through the corresponding selected aperture plane aperture at a plurality of various intensities of the effective source includes using a minimum intensity equal to;

Emin=E0*(Wsource/Wpinhole)/10

and using a maximum intensity equal to;

Emax=E0*(Wsource/Wpinhole)*5

where;

E0=E-zero or dose where an open frame photoresist exposure just clears

Wsource =the solid angle of the source on the image side; and

,

Wpinhole =the solid angle of the pinhole as seen from the image side.

6. The process of measuring the radiant intensity profile of an effective source of an projection image system according to claim 1 wherein the analyzing the recorded images of the effective source on the media for the selected field point includes:

taking machine readable images.

7. The process of measuring the radiant intensity profile of an effective source of an projection image system according to claim 1 wherein the analyzing the recorded images of the effective source on the media for the selected field point includes:

producing a contour plot of the radiant intensity profile.

8. The process of measuring the radiant intensity profile of an effective source of an projection image system according to claim 1 wherein the analyzing the recorded images of the effective source on the media for the selected field point includes:

producing a three dimensional plot of the radiant intensity profile.

9. The process of measuring the radiant intensity profile of an effective source of an projection image system according to claim 1 wherein the recording of the recorded images of the effective source on the media for the selected field point includes:

recording the machine readable images on a charge coupled device (CCD).

10. The process of measuring the radiant intensity profile of an effective source of an projection image system according to claim 1 wherein the recording of the recorded images of the effective source on the media for the selected field point includes:

recording the images utilizes a line type detector; and

,

moving the line type detector in one dimension across the image plane.

11. The process of measuring the radiant intensity profile of an effective source of an projection image system according to claim 1 wherein the recording of the recorded images of the effective source on the media for the selected field point includes:

reflecting the images from the image plane to an image recorder.

12. The process of measuring the radiant intensity profile of an effective source of an projection image system according to claim 1 wherein the recording of the recorded images of the effective source on the media for the selected field point includes:

providing a wafer chuck having an image recorder; and

,

recording the image at the image recorder.

14. Apparatus for measuring the radiant intensity profile of an effective source of an projection image system according to claim 13 and wherein:

the means for recording the plurality of effective source images of the selected field points on recording media at the image plane includes a reflecting media at the image plane and a detector removed from the image plane.

15. Apparatus for measuring the radiant intensity profile of an effective source of an projection image system according to claim 13 and wherein:

the means for recording the plurality of effective source images of the selected field points on recording media at the image plane includes a charged couple device and lenses for sizing the image with respect to the charge coupled device.

13. Apparatus for measuring the radiant intensity profile of an effective source of an projection image system having an effective source, an object plane, an imaging objective, an exit pupil, and an image plane, the apparatus comprising:

an array of field points on an object plane of the projection imaging system;

a corresponding array of aperture plane apertures displaced from the object plane a sufficient distance to image the effective source, the array of corresponding object plane apertures corresponding to the field points on the object plane;

means for selecting at least one field point and a corresponding aperture plane aperture;

means for projecting a plurality of images of the selected field point through the corresponding selected aperture plane aperture at a plurality of various intensities of the effective source to produce at the image plane a corresponding plurality of images of the effective source image at the selected field point;

means for recording the plurality of effective source images of the selected field points on recording media at the image plane to produce recorded images for each of the plurality of various intensities; and

,

means for analyzing the recorded images of the effective source on the media for the selected field point and aperture plane aperture to determine a radiant intensity profile of the image source at the selected field point.