Evaluation method, adjustment method, exposure apparatus, and memory medium

• US 8,941,813 B2
• Filed: 02/10/2009
• Issued: 01/27/2015
• Est. Priority Date: 02/12/2008
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Arai, Tadashi
• Primary Examiner(s): Ton, Toan
• Assistant Examiner(s): Sanei, Mona M
• Application Number:
  US12/368,892
• Publication Number:
  US 20090201480A1
• Time in Patent Office: 2,177 Days
• Field of Search: 355/30, 355/52, 355/53, 355/55, 355/67, 355/71, 359/341.1, 359/352, 700/59
• US Class Current: 355/67
• CPC Class Codes: G02B 27/28 for polarising used in stereoscopes G02B30/25
• CPC Class Codes: G03B 27/54 Lamp housings; Illuminating means
• CPC Class Codes: G03F 7/70258 Projection system adjustments, e.g. adjustments during exposure or alignment during assembly of projection system
• CPC Class Codes: G03F 7/70566 Polarisation control
• CPC Class Codes: G03F 7/706 Aberration measurement

Abstract

A method evaluating an imaging performance of a projection optical system according to a polarization state of light in a pupil of an illumination optical system for an exposure apparatus, comprises a representation step of numerically representing the polarization state in the pupil of the illumination optical system, an assumption step of virtually dividing the pupil of the illumination optical system into a plurality of partial regions, each of which includes a light incident region and a light non-incident region, and assuming individual polarization states for the plurality of partial regions so that one polarization state is assumed for the whole of each partial region based on the polarization state numerically represented in the representation step; and a calculation step of calculating the imaging performance of the projection optical system under a condition in which the plurality of partial regions have the polarization states individually assumed in the assumption step.

Claims

1. A method of evaluating an aberration of a projection optical system for an exposure apparatus which illuminates an original by an illumination optical system and projects a pattern of the original onto a substrate by the projection optical system, the method comprising:

setting an effective light source distribution and a polarization state in a pupil of the illumination optical system, the effective light source distribution including a plurality of poles each having a light intensity higher than a predetermined value;

dividing the pupil of the illumination optical system into a plurality of first partial regions in accordance with an arrangement of the plurality of poles in the effective light source distribution, and dividing a pupil of the projection optical system into a plurality of second partial regions respectively corresponding to the plurality of first partial regions of the pupil of the illumination optical system;

assuming polarization states for the plurality of second partial regions of the pupil of the projection optical system so that one polarization state that is determined based on a polarization state in the pole of a first partial region of the plurality of first partial regions is assumed for a whole of a corresponding second partial region of the plurality of second partial regions; and

determining a polarization state of light which emerges from the projection optical system, under a condition in which the plurality of second partial regions have the assumed polarization states, based on characteristics of a polarization change of the projection optical system that represents a relationship between a polarization state of light which enters the projection optical system and light that emerges from the projection optical system, and calculating the aberration of the projection optical system based on the determined polarization state.

2. The method according to claim 1, wherein the pupil of the illumination optical system is divided between the poles of the plurality of poles.

3. The method according to claim 1, wherein the polarization state is represented by at least one of Stokes parameters, a Jones vector, and a degree of polarization.

4. The method according to claim 1, wherein characteristics of a polarization change of the projection optical system, which is represented by at least one of a Mueller matrix and a Jones matrix, is used in the calculation of the imaging performance.

5. The method according to claim 1, wherein the polarization state in a whole of each of the plurality of second partial regions is represented by Jones Vector having same values.

6. An exposure apparatus comprising:

an illumination optical system configured to illuminate an original;

a projection optical system configured to project a pattern of the original; and

a control unit configured to adjust the projection optical system based on an aberration of said projection optical system,

wherein said control unit executes a process including;

setting an effective light source distribution and a polarization state in a pupil of said illumination optical system, the effective light source distribution including a plurality of poles each having a light intensity higher than a predetermined value,

dividing the pupil of the illumination optical system into a plurality of first partial regions in accordance with an arrangement of the plurality of poles in the effective light source distribution, and dividing a pupil of the projection optical system into a plurality of second partial regions respectively corresponding to the plurality of first partial regions of the pupil of the illumination optical system,

assuming polarization states for the plurality of second partial regions of the pupil of the projection optical system so that one polarization state that is determined based on a polarization state in the pole of a first partial region of the plurality of first partial regions is assumed for a whole of a corresponding second partial region of the plurality of second partial regions,

determining a polarization state of light which emerges from the projection optical system, under a condition in which the plurality of second partial regions have the assumed polarization states, based on characteristics of a polarization change of the projection optical system that represents a relationship between a polarization state of light which enters the projection optical system and light that emerges from the projection optical system, and calculating the aberration of the projection optical system based on the determined polarization state, and

adjusting the projection optical system based on the calculated aberration.

7. A non-transitory memory medium storing a computer program for making a computer execute a process for evaluating aberration of a projection optical system for an exposure apparatus which illuminates an original by an illumination optical system and projects a pattern of the original onto a substrate by the projection optical system, the process comprising:

setting an effective light source distribution and a polarization state in a pupil of said illumination optical system, the effective light source distribution including a plurality of poles each having a light intensity higher than a predetermined value;

dividing the pupil of the illumination optical system into a plurality of first partial regions in accordance with an arrangement of the plurality of poles in the effective light source distribution, and dividing a pupil of the projection optical system into a plurality of second partial regions respectively corresponding to the plurality of first partial regions of the pupil of the illumination optical system;

assuming polarization states for the plurality of second partial regions of the pupil of the projection optical system so that one polarization state that is determined based on a polarization state in the pole of a first partial region of the plurality of first partial regions is assumed for a whole of a corresponding second partial region of the plurality of second partial regions; and

determining a polarization state of light which emerges from the projection optical system, under a condition in which the plurality of second partial regions have the assumed polarization states, based on characteristics of a polarization change of the projection optical system that represents a relationship between a polarization state of light which enters the projection optical system and light that emerges from the projection optical system, and calculating the aberration of the projection optical system based on the determined polarization state.