EVALUATION METHOD, ADJUSTMENT METHOD, EXPOSURE APPARATUS, AND MEMORY MEDIUM

• US 20090201480A1
• Filed: 02/10/2009
• Published: 08/13/2009
• 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
• Granted Patent: US 8,941,813 B2
• Time in Patent Office: Days
• 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 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 which illuminates an original by the illumination optical system and projects a pattern of the original onto a substrate by the projection optical system, the method comprising:

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.

2. The method according to claim 1, wherein in the assumption step, the pupil is divided between poles each serving as a region having a light intensity higher than a predetermined value in the pupil of the illumination optical system.

3. The method according to claim 1, wherein in the representation step, the polarization state in the pupil of the illumination optical system is numerically represented by at least one of Stokes parameters, a Jones vector, and a degree of polarization.

4. The method according to claim 1, wherein in the calculation step, the imaging performance of the projection optical system is calculated under a condition in which the plurality of partial regions have the polarization states individually assumed in the assumption step, based on a polarization change of the projection optical system, which represents a relationship between a polarization state of the light which enters the projection optical system and a polarization state of the light which emerges from the projection optical system.

5. The method according to claim 4, wherein in the calculation step, 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 of the projection optical system.

6. A method of adjusting an imaging performance of a projection optical system in accordance with a polarization state of light in a pupil of an illumination optical system for an exposure apparatus which illuminates an original by the illumination optical system and projects a pattern of the original onto a substrate by the projection optical system, the method comprising:

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;

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; and

an adjustment step of adjusting the imaging performance of the projection optical system based on the imaging performance calculated in the calculation step.

7. 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 illuminated by said illumination optical system onto a substrate; and

a control unit configured to adjust an imaging performance of said projection optical system,

wherein said control unit executes a process including

a representation step of numerically representing the polarization state in the pupil of said illumination optical system,

an assumption step of virtually dividing the pupil of said 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,

a calculation step of calculating the imaging performance of said projection optical system under a condition in which the plurality of partial regions have the polarization states individually assumed in the assumption step, and

an adjustment step of adjusting the imaging performance of said projection optical system based on the imaging performance calculated in the calculation step.

8. A memory medium storing a computer program for making a computer execute a process for 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 which illuminates an original by the illumination optical system and projects a pattern of the original onto a substrate by the projection optical system, the process comprising:

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.

9. A memory medium storing a computer program for making a computer execute a process for adjusting an imaging performance of a projection optical system in accordance with a polarization state of light in a pupil of an illumination optical system for an exposure apparatus which illuminates an original by the illumination optical system and projects a pattern of the original onto a substrate by the projection optical system, the process comprising:

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;

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; and

an adjustment step of adjusting the imaging performance of the projection optical system based on the imaging performance calculated in the calculation step.