CN109416457B

CN109416457B - Optical device, exposure device, and method for manufacturing article

Info

Publication number: CN109416457B
Application number: CN201780040473.6A
Authority: CN
Inventors: 柴田雄吾; 长野浩平
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2016-07-06
Filing date: 2017-06-16
Publication date: 2021-09-17
Anticipated expiration: 2037-06-16
Also published as: KR102165797B1; CN109416457A; KR20190020139A; JP2018005068A; JP6929024B2; WO2018008364A1

Abstract

Provided is an optical device capable of suppressing heat generation associated with shape correction of an optical element and correcting the shape with high accuracy. An optical device (10) for deforming a reflection surface (1a) of a mirror (1) comprises: a base plate (5) disposed separately from a rear surface (1b) which is the surface opposite to the reflection surface (1 a); and a correction unit (2) that includes a mirror-side magnet (3) attached to the surface on the opposite side of the reflection surface (1a), and a base-side magnet (4) disposed at the position of the bottom plate (5) that faces the mirror-side magnet (3). The correction unit (2) corrects the shape of the reflection surface (1a) by using the repulsive force or attractive force generated by the mirror-side magnet (3) and the base-side magnet (4).

Description

Optical device, exposure device, and method for manufacturing article

Technical Field

The invention relates to an optical device, an exposure apparatus and a method for manufacturing an article.

Background

In order to improve the resolution of an exposure apparatus used for manufacturing semiconductor devices and the like, it is required to correct various optical characteristics of a projection optical system in the exposure apparatus, such as optical aberration, image magnification, image distortion, and focus. The correction of the optical characteristics is achieved by deforming the shape of the mirror included in the projection optical system from a reference shape. Here, when the shape of the mirror deviates from the reference shape due to a machining error or the like and has a shape error, it is necessary to deform the mirror in consideration of the shape error in order to correct the optical characteristics. Patent document 1 discloses a technique of correcting a shape error with respect to an ideal shape (reference shape) generated by screw fastening at the time of mirror mounting by driving an electromagnet actuator.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2-101402

Disclosure of Invention

However, in the case where the shape error is corrected by the electromagnet actuator using the technique of the above-mentioned document, and the mirror is deformed in order to correct the optical characteristics, unintended deformation occurs in the mirror due to heat generation from the electromagnet actuator, and new optical aberration may be generated.

An object of the present invention is to provide an optical device capable of suppressing heat generation associated with shape correction of an optical element and correcting the shape with high accuracy.

In order to solve the above problem, one aspect of the present invention provides an optical device in which a reflection surface of an optical element is deformed, the optical device including: a bottom plate disposed apart from a surface on the opposite side of the reflection surface; and a correction unit including a1 st permanent magnet attached to a surface on an opposite side of the reflection surface and a2 nd permanent magnet disposed at a position of the base plate facing the 1 st permanent magnet, the correction unit correcting a shape of the reflection surface by using a repulsive force or an attractive force generated by the 1 st permanent magnet and the 2 nd permanent magnet.

According to the present invention, for example, an optical device capable of suppressing heat generation associated with shape correction of an optical element and correcting the shape with high accuracy can be provided.

Drawings

Fig. 1 is a diagram showing a schematic configuration of an exposure apparatus according to embodiment 1.

Fig. 2 is a cross-sectional view showing a schematic configuration of the optical device according to embodiment 1.

Fig. 3 is a front view showing a schematic configuration of an optical device according to embodiment 1.

Fig. 4 is a cross-sectional view showing a schematic configuration of an optical device according to embodiment 2.

Fig. 5 is a front view showing a schematic configuration of an optical device according to embodiment 2.

Description of the reference numerals

1: a mirror; 2: a correction unit; 3: a mirror-side magnet; 4: a base-side magnet; 5: a base plate.

Detailed Description

Fig. 1 is a diagram showing a schematic configuration of an exposure apparatus. The exposure apparatus 50 includes an illumination optical system IL, a projection optical system UM, a mask stage MS capable of holding and moving the mask 55, and a substrate stage PS capable of holding and moving the substrate 56. The exposure apparatus 50 includes a control unit 51 that controls a process of exposing the substrate 56.

Light emitted from a light source (not shown) included in the illumination optical system IL can form an arc-shaped illumination region, for example, long in the Y direction, on the mask 55 by a slit (not shown) included in the illumination optical system IL. The mask 55 and the substrate 56 are held by the mask stage MS and the substrate stage PS, respectively, and are disposed at positions substantially optically conjugate with each other (positions of an object plane and an image plane of the projection optical system UM) through the projection optical system UM. The projection optical system UM has a predetermined projection magnification (for example, 1/2 times), and projects the pattern formed on the mask 55 onto the substrate 56. Then, the mask stage MS and the substrate stage PS are scanned in a direction parallel to the object plane of the projection optical system UM (for example, in the X direction in fig. 1) at a speed ratio corresponding to the projection magnification of the projection optical system UM. This allows the pattern formed on the mask 55 to be transferred to the substrate 56.

The projection optical system UM includes, for example, a flat mirror 52, a mirror 1 as a concave mirror, and a convex mirror 54 as shown in fig. 1. The exposure light emitted from the illumination optical system IL and transmitted through the mask 55 is bent in its optical path by the 1 st surface 52a of the flat mirror 52, and enters the 1 st surface 1a1 of the mirror 1. The exposure light reflected by the 1 st surface 1a1 of the mirror 1 is reflected by the convex mirror 54 and enters the 2 nd surface 1a2 of the mirror 1. The exposure light reflected by the 2 nd surface 1a2 of the mirror 1 is bent in the optical path by the 2 nd surface 52b of the flat mirror 52, and forms an image on the substrate 56.

Embodiment 1

Next, the optical device 10 and the method for correcting a shape error according to embodiment 1 will be described with reference to fig. 2 and 3. The optical device 10 is, for example, a large-aperture concave mirror device used in a mirror type exposure apparatus. Fig. 2 is a cross-sectional view of an optical device. The optical device 10 includes a mirror 1, a base plate 5, and a plurality of shape error correction units (correction units) 2. The mirror 1 is an optical element having a reflection surface 1a that reflects light and a back surface 1b that is a surface opposite to the reflection surface. The mirror 1 is fixed to the base plate 5 via a fixing member 6. The bottom plate 5 is disposed apart from the back surface 1 b.

The correction unit 2 is disposed between the mirror 1 and the bottom plate 5, and includes a1 st permanent magnet (mirror-side magnet) 3 disposed on the mirror side of the back surface 1b of the mirror 1 and a2 nd permanent magnet (base-side magnet) 4 disposed on the base side of the bottom plate 5 facing thereto. The correction unit 2 can generate an attractive force or a repulsive force by reversing the polarity of the base-side magnet 4 facing the mirror-side magnet 3. Further, the amount of force generated can be adjusted by adjusting the magnet-to-magnet distance between the mirror-side magnet 3 and the opposing base-side magnet 4 using the adjustment mechanism 13. Specifically, the distance between the magnets is adjusted by adjusting the position of the arrangement of the base-side magnet 4 by the adjustment mechanism 13. In the present embodiment, the case where the polarity of the base-side magnet 4 is changed has been described, but the present invention is not limited to this, and the attractive force and the repulsive force may be switched by changing the polarity of the mirror-side magnet 3.

Next, a shape error correction method of the mirror 1 using the correction unit 2 is explained. The shape of the reflecting surface 1a of the mirror 1 is measured by using the measuring unit 12, and the direction and amount of force (shape error) necessary for correcting the shape error are calculated. The measuring unit 12 is constituted by a measuring instrument for measuring the shape of the reflecting surface 1a of the mirror 1, such as a laser interferometer or Shack-Hartmann Sensor.

The polarity of the base-side magnet 4 of each correction unit 2 is selected according to the positive and negative (concave and convex) of the shape error indicating the direction and amount of force necessary for correcting the shape error, and any force of the attraction force or the repulsion force is generated. The distance between the mirror-side magnet 3 and the base-side magnet 4 of each correction unit 2 is adjusted by the adjustment mechanism 13 according to the magnitude of the shape error, and the generated force is adjusted. Tensile or compressive stresses are locally generated in the mirror 1 by a plurality of correction cells 2. Therefore, the mirror surface 1a is locally elastically deformed in accordance with the tensile stress or the compressive stress, and the shape error of the mirror surface 1a is corrected. In the optical device 10 of the present embodiment, the correction unit 2 made of a permanent magnet is used, and the shape error of the mirror 1 can be corrected without generating heat by the shape correction mechanism.

Next, referring to fig. 3, the configuration of the correction unit 2 is explained. Fig. 3 is a front view of the optical device 10 viewed in the direction of arrow a in fig. 2. The correction units 2 are arranged at 4 positions at 90 ° intervals on the same circumference, and are further arranged at 8 positions at 45 ° intervals on the outer circumference apart from the 4 positions. However, the arrangement of the correction unit 2 is not limited thereto, and the number and arrangement may be changed according to the optical aberration to be corrected.

The optical device of the present embodiment can be variously modified within a range not departing from the gist. For example, the number, arrangement, and the like of the correction units 2 can be arbitrarily set. Further, the outer peripheral portion of the mirror 1 is fixed to the base plate 5 by the fixing member 6, but an arbitrary portion of the mirror 1 may be fixed to the base plate 5 by the fixing member 6. Further, means such as screwing or bonding may be employed for coupling the mirror 1 and the base plate 5. In embodiment 1, an example in which a spherical mirror having a circular concave surface is used as the mirror 1 has been described, but the present invention is not limited to this, and for example, a plane mirror or a spherical mirror having a convex surface may be used as the mirror 1. The measurement unit 12 is described by taking a sensor for measuring a surface shape as an example, but a sensor array including a plurality of displacement sensors for measuring a plurality of positions of the mirror 1 may be used.

Embodiment 2

Next, the optical device 20 and the method for correcting a shape error according to embodiment 2 will be described with reference to fig. 4 and 5. In fig. 4 and 5, the same reference numerals are given to the components common to embodiment 1, and the description thereof is omitted. Fig. 4 is a sectional view of the optical device of embodiment 2. The optical device 20 is, for example, a large-aperture concave mirror device used in a mirror-type exposure apparatus, and can be applied to the mirror 1 in the exposure apparatus of fig. 1. The optical device 20 according to embodiment 2 corrects optical aberrations of the projection optical system, and the magnification, distortion, and focus of the projected image by deforming the reflection surface 1a of the mirror 1 included in the projection optical system of the exposure apparatus, for example. The optical device 20 includes a mirror 1, a base plate 5, a plurality of actuators 7, a plurality of displacement sensors 14, and a control unit 11.

The control unit 11 has a CPU, a memory, and the like, and controls the displacement sensor 14 and the plurality of actuators 7. The actuator 7 is disposed between the mirror 1 and the base plate 5, and applies a force to the back surface 1b of the mirror 1. The actuator 7 has a mover magnet 8 fixed to the back surface 1b and a stator coil 9 fixed to the base plate 5. The displacement sensor 14 measures the distance up to the back surface 1b of the mirror 1. The control unit 11 calculates a drive command value of the actuator 7 based on the measurement value of the displacement sensor 14, and generates a desired force. This enables the reflection surface 1a of the mirror 1 to be deformed at high speed and with high accuracy, and optical aberration in the projection optical system UM can be corrected in real time and with high accuracy.

In addition, the optical device 20 has a correction unit 2. The correction unit 2 is disposed between the mirror 1 and the bottom plate 5, and includes a mirror-side magnet 3 provided on the back surface 1b of the mirror 1 and a base-side magnet 4 disposed on the opposing bottom plate 5. The shape correction method performed by the correction unit 2 is the same as that of embodiment 1. For measuring the shape error, the measuring unit 12 may be used as in embodiment 1, or the displacement sensor 14 may be used.

When the shape error due to the assembly error or machining error of the mirror 1 is corrected by the actuators 7, a required force must be constantly generated in accordance with the shape error, and therefore, heat generation increases, and unintended deformation is given to the mirror 1. However, by correcting the shape error due to the assembly error or the machining error by using the correction means 2, the shape error due to the assembly error or the machining error can be corrected without generating heat. Accordingly, each actuator only needs to generate a force necessary for a deformation driving amount necessary for correcting optical aberration in the projection optical system UM, and therefore, heat generation can be relatively suppressed. Further, in the optical device 20 that performs the deforming drive by the plurality of actuators as in embodiment 2, generally speaking, the machining accuracy required for the mirror 1 is high, but the machining error can be corrected by the correcting means 2, so that the machining time and the machining cost of the mirror 1 can be suppressed.

Next, the arrangement of the correction unit 2 and the actuator 7 will be described with reference to fig. 5. Fig. 5 is a front view of the optical device 20 when viewed in the direction of arrow B of fig. 4. In embodiment 2, the correction unit 2 and the actuator 7 are arranged at 4 positions on the same circumference at 90 ° intervals, and are further arranged at 8 positions on the outer circumference apart from the 4 positions at 45 ° intervals. However, the arrangement of the correction unit 2 and the actuator 7 is not limited to this, and the number and arrangement may be changed according to the optical aberration to be corrected.

In embodiment 2, the center portion of the mirror 1 is fixed to the base plate 5 by the fixing member 6, but an arbitrary portion of the mirror 1 may be fixed to the base plate 5 by the fixing member 6. As each actuator 7, for example, a Voice Coil Motor (VCM), a non-contact type actuator including a mover magnet 8 and a stator Coil 9 which are not in contact with each other, or a displacement actuator such as a piezoelectric element may be used.

As described above, by performing the shape correction of the optical device by the correction means composed of the permanent magnet, it is possible to perform the shape correction with high accuracy without generating heat associated with the shape correction as in embodiment 1 or by suppressing the heat generation as in embodiment 2. In the above-described embodiments, an example of application to an exposure apparatus has been described, but examples of apparatuses to which the optical apparatus of the above-described embodiments can be applied include a lithography apparatus in which a latent image pattern of a resist is formed on a substrate by irradiation with EUV light. In addition, the present invention can be applied to a laser processing apparatus, a fundus imaging apparatus, a telescope, and the like.

Embodiment of method for manufacturing article

The method for manufacturing an article according to the present embodiment is suitable for manufacturing articles such as a micro device such as a semiconductor device and an element having a microstructure, for example. The method of manufacturing an article according to the present embodiment includes a step of forming a latent image pattern on a photosensitive agent applied to a substrate by using the exposure apparatus (a step of exposing the substrate), and a step of developing the substrate on which the latent image pattern is formed in the step. The above-described manufacturing method further includes other known steps (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, and the like). The method for manufacturing an article according to the present embodiment is advantageous in at least 1 of the performance, quality, productivity, and production cost of the article, as compared with the conventional method.

While the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist of the present invention.

Claims

1. An optical device for deforming a reflection surface of an optical element, the optical device comprising:

a bottom plate disposed apart from a surface on the opposite side of the reflection surface;

a displacement sensor that measures a distance between the bottom plate and a surface on an opposite side of the reflection surface;

a correcting unit including a1 st permanent magnet attached to a surface on the opposite side of the reflecting surface, and a2 nd permanent magnet disposed at a position of the base plate facing the 1 st permanent magnet; and

an actuator including a 3 rd magnet attached to a surface on the opposite side of the reflection surface and located at a position different from the 1 st permanent magnet, and a coil arranged at a position of the bottom plate facing the 3 rd magnet,

the correction unit applies a repulsive force or an attractive force generated by the 1 st permanent magnet and the 2 nd permanent magnet to the optical element so as to reduce a shape error measured by a measurement unit that measures a shape of the reflection surface,

in a state where the correction means reduces the shape error of the reflecting surface, the actuator applies a force to the optical element to change the optical characteristics of the optical device based on the measurement value of the displacement sensor, thereby changing the shape of the reflecting surface.

2. The optical device according to claim 1,

the actuator applies a force to a position of the optical element different from a position at which the correction unit applies a force to the optical element.

3. The optical device according to claim 1,

the correction unit corrects the shape of the reflection surface using a repulsive force or an attractive force generated by the 1 st permanent magnet and the 2 nd permanent magnet.

4. The optical device according to claim 3,

the repulsive force and the attractive force are switched by changing the polarity of the 2 nd permanent magnet.

5. The optical device according to claim 4,

the polarity of the 2 nd permanent magnet is changed according to a shape error measured by a measuring part that measures the shape of the reflection surface.

6. The optical device according to claim 1,

the optical device is also provided with an adjusting mechanism, and the adjusting mechanism adjusts the distance between the 1 st permanent magnet and the 2 nd permanent magnet by adjusting the position of the 2 nd permanent magnet.

7. The optical device according to claim 6,

the adjusting mechanism adjusts the position of the 2 nd permanent magnet according to a shape error measured by a measuring unit that measures the shape of the reflection surface.

8. The optical device according to claim 1,

the displacement sensor is configured on the bottom plate.

9. The optical device according to claim 8,

the actuator is driven according to the distance measured by the displacement sensor.

10. An exposure apparatus, characterized in that,

the exposure apparatus has the optical apparatus according to claim 1.

11. A method of manufacturing an article, comprising:

exposing a substrate using the exposure apparatus according to claim 10; and

a step of developing the substrate exposed to light,

fabricating an article from the developed substrate.