# US 2017/0285485 A1 · Exposure apparatus, exposure method, and device manufacturing method

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- Number: US 2017/0285485 A1
- Document ID: US20170285485A1
- Status: Published application
- Kind: A1
- Application number: 15/628,982
- Filed: 2017-06-21
- Published: 2017-10-05
- Earliest claimed: 2009-08-25
- Assignees: Nikon Corporation
- Applicants: Nikon Corporation
- Inventors: Yuichi SHIBAZAKI
- Web page: https://patentgrep.com/patent/US20170285485A1

## CPC

- G03F 7/70108: {Off-axis setting using a light-guiding element, e.g. diffractive optical elements [DOEs] or light guides}
- G03F 7/70058: {Mask illumination systems}
- G03F 7/70191: {Optical correction elements, filters or phase plates for controlling intensity, wavelength, polarisation, phase or the like}
- G03F 7/70516: {Calibration of components of the microlithographic apparatus, e.g. light sources, addressable masks or detectors}
- G03F 7/70725: {control}
- G03F 7/70758: {Drive means, e.g. actuators, motors for long- or short-stroke modules or fine or coarse driving}
- G03F 7/70775: {Position control, e.g. interferometers or encoders for determining the stage position}
- G03F 7/70975: {Assembly, maintenance, transport or storage of apparatus}
- G03F 9/70: {for microlithography (measuring printed patterns for monitoring overlay G03F7/70633 or focus G03F7/70641; projection system adjustment G03F7/70258; position control G03F7/70775)}
- G03F 9/7046: {Strategy, e.g. mark, sensor or wavelength selection}
- Y10T 29/49004: including measuring or testing of device or component part
- G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

An exposure apparatus is equipped with an encoder system which measures positional information of a wafer stage by irradiating a measurement beam using four heads installed on the wafer stage on a scale plate which covers the movement range of the wafer stage except for the area right under a projection optical system. Placement distances of the heads here are each set to be larger than width of the opening of the scale plates, respectively. This allows the positional information of the wafer stage to be measured, by switching and using the three heads facing the scale plate out of the four heads according to the position of the wafer stage.

## Claims

### Claim 1

An exposure apparatus that exposes a substrate with illumination light via a projection optical system, the apparatus comprising:
a body having a metrology frame to support the projection optical system;
an alignment system provided at the metrology frame in a measurement station, that detects a mark of the substrate, the measurement station being different from an exposure station in which exposure of the substrate is performed via the projection optical system;
a base disposed below the projection optical system and the alignment system;
a stage having a holder to hold the substrate, and disposed on the base;
a drive system having a magnetic levitation type planar motor to drive the stage on the base;
a first scale member having four L-shaped sections in each of which a reflection-type grating is formed and a first opening substantially surrounded by the four sections, the first scale member being provided at the metrology frame so that the projection optical system is located in the first opening and the first scale member is disposed on a lower end side of the projection optical system in the exposure station, and the stage being placed facing the first scale member in an exposure operation of the substrate;
a second scale member having four L-shaped sections in each of which a reflection-type grating is formed and a second opening substantially surrounded by the four sections, the second scale member being provided at the metrology frame so that the alignment system is located in the second opening and the second scale member is disposed on a lower end side of the alignment system in the measurement station, and the stage being placed facing the second scale member in a detection operation of the mark by the alignment system;
an encoder system that has four heads provided at the stage and measures positional information of the stage, each of the four heads irradiating the first scale member or the second scale member from below with a measurement beam; and
a controller that controls the drive system based on measurement information of the encoder system, and switches one head of three heads used in the measurement to another head, of the four heads, during movement of the stage, wherein
the four heads are provided at the stage so that a distance between two heads of the four heads is larger than each of a width of the first opening and a width of the second opening in a first direction, and a distance between two heads of the four heads is larger than each of a width of the first opening and a width of the second opening in a second direction, the first direction being in a predetermined plane orthogonal to an optical axis of the projection optical system, and the second direction being orthogonal to the first direction in the predetermined plane,
a movement area of the stage in the exposure operation includes a first area, a second area, a third area, a fourth area and a fifth area,
in the first area, three heads of the four heads except for a first head respectively facing three sections of the four sections of the first scale member except for a first section,
in the second area, three heads of the four heads except for a second head different from the first head respectively facing three sections of the four sections except for a second section different from the first section,
in the third area, three heads of the four heads except for a third head different from the first and the second heads respectively facing three sections of the four sections except for a third section different from the first and the second sections,
in the fourth area, three heads of the four heads except for a fourth head different from the first, the second and the third heads respectively facing three sections of the four sections except for a fourth section different from the first, the second and the third sections, and
in the fifth area, the four heads respectively facing the four sections,
in the exposure operation, the stage is moved from one area of the first, the second, the third and the fourth areas to another area of the first, the second, the third and the fourth areas that is different from the one area, via the fifth area,
the controller switches the one head to the another head when the stage is moved from the fifth area to the another area.

### Claim 2 (depends on 1)

The exposure apparatus according to claim 1, wherein
the switching is performed while the stage is in the fifth area.

### Claim 3 (depends on 1)

The exposure apparatus according to claim 1, wherein
in a part of the another area, the one head does not face one section to which the one head faces in the one area, of the four sections of the first scale member, and
in a part of the one area, the another head does not face one section to which the another head faces in the another area, of the four sections of the first scale member.

### Claim 4 (depends on 1)

The exposure apparatus according to claim 1, wherein
the controller moves the stage in the another area, using correction information for compensating for a measurement error of the encoder system, the measurement error occurring due to performing drive control of the stage by three heads used in the another area, instead of drive control of the stage by three heads used in the one area.

### Claim 5 (depends on 4)

The exposure apparatus according to claim 4, wherein
the correction information is acquired while the stage is in the fifth area.

### Claim 6 (depends on 4)

The exposure apparatus according to claim 4, wherein
the measurement error occurs due to one of the heads and one of the sections used in the measurement being different between the one area and the another area.

### Claim 7 (depends on 4)

The exposure apparatus according to claim 4, wherein
the correction information includes an offset for compensating for a difference between positional information of the stage in the fifth area obtained from three heads used in the one area and positional information of the stage in the fifth area obtained from three heads used in the another area.

### Claim 8 (depends on 1)

The exposure apparatus according to claim 1, wherein
the encoder system is capable of measuring positional information of the stage in directions of six degrees of freedom, the directions of six degrees of freedom including the first and the second directions and a third direction orthogonal to the predetermined plane, and
each of the four heads is capable of measuring positional information of the stage in two directions, the two directions being a direction parallel to the predetermined plane and a direction perpendicular to the predetermined plane.

### Claim 9 (depends on 1)

The exposure apparatus according to a claim 1, wherein
each of the first and the second scale members has a reflection-type two-dimensional grating formed, and is supported in a suspended manner by the metrology frame so that the two-dimensional grating is substantially parallel to the predetermined plane.

### Claim 10 (depends on 1)

The exposure apparatus according to claim 1, wherein
each of the first and the second scale members has a non-effective area on an outer periphery of the four sections.

### Claim 11 (depends on 1)

The exposure apparatus according to claim 1, wherein
the first and the second scale members are arranged so that the reflection-type gratings are substantially flush.

### Claim 12 (depends on 1)

The exposure apparatus according to claim 1, wherein
the encoder system has at least one head that is different from the four heads and is disposed in proximity to each of the four heads.

### Claim 13 (depends on 1)

The exposure apparatus according to claim 1, wherein
the controller controls movement of the stage while compensating for a measurement error of the encoder system that occurs due to at least one of a production error of the scale member, acceleration of the stage and a position or tilt of the head.

### Claim 14 (depends on 1)

The exposure apparatus according to claim 1, further comprising:
another stage disposed on the base and different from the stage, wherein
the encoder system has four heads that are provided at the another stage and different from the four heads provided at the stage, and the encoder system measures positional information of the another stage with at least three heads of the four heads provided at the another stage.

### Claim 15 (depends on 1)

A device manufacturing method, comprising:
exposing a substrate using the exposure apparatus according to claim 1; and
developing the substrate that has been exposed.

### Claim 16

An exposure method of exposing a substrate with illumination light via a projection optical system, the method comprising:
moving a stage having a holder to hold the substrate, with a magnetic levitation type planar motor that drives the stage, on a base disposed below the projection optical system and an alignment system in an exposure station and a measurement station, in the exposure station an exposure operation of the substrate being performed via the projection optical system, the measurement station being different from the exposure station, and in the measurement station a detection operation of a mark of the substrate being performed by the alignment system, and the alignment system being provided at a metrology frame that supports the projection optical system;
in the exposure station, measuring positional information of the stage in the exposure operation, with an encoder system having four heads provided at the stage, each of the four heads irradiating a first scale member from below with a measurement beam, the first scale member having four L-shaped sections in each of which a reflection-type grating is formed and a first opening substantially surrounded by the four sections, and the first scale member being provided at the metrology frame so that the projection optical system is located in the first opening and the first scale member is disposed on a lower end side of the projection optical system;
in the measurement station, measuring positional information of the stage in the detection operation, with the encoder system having the four heads provided at the stage, each of the four heads irradiating a second scale member from below with the measurement beam, the second scale member having four L-shaped sections in each of which a reflection-type grating is formed and a second opening substantially surrounded by the four sections, and the second scale member being provided at the metrology frame so that the alignment system is located in the second opening and the second scale member is disposed on a lower end side of the alignment system;
controlling movement of the stage based on measurement information of the encoder system; and
switching one head of three heads used in the measurement to another head, of the four heads, during movement of the stage, wherein
the four heads are provided at the stage so that a distance between two heads of the four heads is larger than each of a width of the first opening and a width of the second opening in a first direction, and a distance between two heads of the four heads is larger than each of a width of the first opening and a width of the second opening in a second direction, the first direction being in a predetermined plane orthogonal to an optical axis of the projection optical system, and the second direction being orthogonal to the first direction in the predetermined plane,
a movement area of the stage in the exposure operation includes a first area, a second area, a third area, a fourth area and a fifth area,
in the first area, three heads of the four heads except for a first head respectively facing three sections of the four sections of the first scale member except for a first section,
in the second area, three heads of the four heads except for a second head different from the first head respectively facing three sections of the four sections except for a second section different from the first section,
in the third area, three heads of the four heads except for a third head different from the first and the second heads respectively facing three sections of the four sections except for a third section different from the first and the second sections,
in the fourth area, three heads of the four heads except for a fourth head different from the first, the second and the third heads respectively facing three sections of the four sections except for a fourth section different from the first, the second and the third sections, and
in the fifth area, the four heads respectively facing the four sections,
in the exposure operation, the stage is moved from one area of the first, the second, the third and the fourth areas to another area of the first, the second, the third and the fourth areas that is different from the one area, via the fifth area,
the one head is switched to the another head when the stage is moved from the fifth area to the another area.

### Claim 17 (depends on 16)

The exposure method according to claim 16, wherein
the switching is performed while the stage is in the fifth area.

### Claim 18 (depends on 16)

The exposure method according to claim 16, wherein
in a part of the another area, the one head does not face one section to which the one head faces in the one area, of the four sections of the first scale member, and
in a part of the one area, the another head does not face one section to which the another head faces in the another area, of the four sections of the first scale member.

### Claim 19 (depends on 16)

The exposure method according to claim 16, wherein
the stage is moved in the another area, using correction information for compensating for a measurement error of the encoder system, the measurement error occurring due to performing drive control of the stage by three heads used in the another area, instead of drive control of the stage by three heads used in the one area.

### Claim 20 (depends on 19)

The exposure method according to claim 19, wherein
the correction information is acquired while the stage is in the fifth area.

### Claim 21 (depends on 16)

The exposure method according to claim 16, wherein
positional information of the stage in directions of six degrees of freedom is measured with the encoder system, the directions of six degrees of freedom including the first and the second directions and a third direction orthogonal to the predetermined plane, and
each of the four heads is capable of measuring positional information of the stage in two directions, the two directions being a direction parallel to the predetermined plane and a direction perpendicular to the predetermined plane.

### Claim 22 (depends on 16)

The exposure method according to claim 16, wherein
each of the first and the second scale members has a reflection-type two-dimensional grating formed, and is supported in a suspended manner by the metrology frame so that the two-dimensional grating is substantially parallel to the predetermined plane, and
the first and the second scale members are arranged so that the reflection-type gratings are substantially flush.

### Claim 23 (depends on 16)

The exposure method according to claim 16, wherein
the switching is performed at a time other than a period of scanning exposure in which the illumination light is irradiated on the substrate, or at a time other than a period of constant speed movement of the stage.

### Claim 24 (depends on 16)

The exposure method according to claim 16, wherein
the stage is moved while a measurement error of the encoder system is compensated for, the measurement error occurring due to at least one of a production error of the scale member, acceleration of the stage and a position or tilt of the head.

### Claim 25 (depends on 16)

A device manufacturing method, comprising:
exposing a substrate using the exposure method according to claim 16; and
developing the substrate that has been exposed.

### Claim 26

A making method of an exposure apparatus that exposes a substrate with illumination light via a projection optical system, the method comprising:
providing a body having a metrology frame to support the projection optical system;
providing an alignment system at the metrology frame in a measurement station, the alignment system detecting a mark of the substrate, and the measurement station being different from an exposure station in which exposure of the substrate is performed via the projection optical system;
providing a base disposed below the projection optical system and the alignment system;
providing a stage having a holder to hold the substrate, and disposed on the base;
providing a drive system having a magnetic levitation type planar motor to drive the stage on the base;
providing a first scale member having four L-shaped sections in each of which a reflection-type grating is formed and a first opening substantially surrounded by the four sections, the first scale member being provided at the metrology frame so that the projection optical system is located in the first opening and the first scale member is disposed on a lower end side of the projection optical system in the exposure station, and the stage being placed facing the first scale member in an exposure operation of the substrate;
providing a second scale member having four L-shaped sections in each of which a reflection-type grating is formed and a second opening substantially surrounded by the four sections, the second scale member being provided at the metrology frame so that the alignment system is located in the second opening and the second scale member is disposed on a lower end side of the alignment system in the measurement station, and the stage being placed facing the second scale member in a detection operation of the mark by the alignment system;
providing an encoder system that has four heads provided at the stage and measures positional information of the stage, each of the four heads irradiating the first scale member or the second scale member from below with a measurement beam; and
providing a controller that controls the drive system based on measurement information of the encoder system, and switches one head of three heads used in the measurement to another head, of the four heads, during movement of the stage, wherein
the four heads are provided at the stage so that a distance between two heads of the four heads is larger than each of a width of the first opening and a width of the second opening in a first direction, and a distance between two heads of the four heads is larger than each of a width of the first opening and a width of the second opening in a second direction, the first direction being in a predetermined plane orthogonal to an optical axis of the projection optical system, and the second direction being orthogonal to the first direction in the predetermined plane,
a movement area of the stage in the exposure operation includes a first area, a second area, a third area, a fourth area and a fifth area,
in the first area, three heads of the four heads except for a first head respectively facing three sections of the four sections of the first scale member except for a first section,
in the second area, three heads of the four heads except for a second head different from the first head respectively facing three sections of the four sections except for a second section different from the first section,
in the third area, three heads of the four heads except for a third head different from the first and the second heads respectively facing three sections of the four sections except for a third section different from the first and the second sections,
in the fourth area, three heads of the four heads except for a fourth head different from the first, the second and the third heads respectively facing three sections of the four sections except for a fourth section different from the first, the second and the third sections, and
in the fifth area, the four heads respectively facing the four sections,
in the exposure operation, the stage is moved from one area of the first, the second, the third and the fourth areas to another area of the first, the second, the third and the fourth areas that is different from the one area, via the fifth area,
the controller switches the one head to the another head when the stage is moved from the fifth area to the another area.