WO2018008364A1

WO2018008364A1 - Optical device, exposure device, and method for manufacturing article

Info

Publication number: WO2018008364A1
Application number: PCT/JP2017/022311
Authority: WO
Inventors: 柴田　雄吾; 浩平長野
Original assignee: キヤノン株式会社
Priority date: 2016-07-06
Filing date: 2017-06-16
Publication date: 2018-01-11
Also published as: KR102165797B1; CN109416457B; CN109416457A; JP6929024B2; KR20190020139A; JP2018005068A

Abstract

Provided is an optical device capable of highly accurately correcting a shape by suppressing heat generated with shape correction of an optical element. An optical device (10) that deforms a reflecting surface (1a) of a mirror (1) has: a base plate (5) that is disposed by being separated from a rear surface (1b), i.e., the surface on the reverse side of the reflecting surface (1a); and a correction unit (2), which includes a mirror-side magnet (3) attached to the surface on the reverse side of the reflecting surface (1a), and a base-side magnet (4) that is disposed at a position in the base plate (5), said position facing the mirror-side magnet (3). The correction unit (2) corrects the shape of the reflecting surface (1a) by means of a repelling force or an attracting force generated by the mirror-side magnet (3) and the base-side magnet (4).

Description

Optical apparatus, exposure apparatus, and method of manufacturing article

The present invention relates to an optical apparatus, an exposure apparatus, and a method of manufacturing an article.

In order to improve the resolution of an exposure apparatus used for manufacturing a semiconductor device or the like, it is required to correct various optical characteristics such as optical aberration, image magnification, image distortion, and focus of a projection optical system in the exposure apparatus. The correction of the optical characteristics is realized by deforming the shape of the mirror included in the projection optical system from the reference shape. Here, if the shape of the mirror deviates from the reference shape due to a processing 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 from an ideal shape (reference shape) generated by screw fastening at the time of mirror attachment by driving an electromagnet actuator.

JP-A-2-101402

However, in the case where the mirror is deformed to correct the optical characteristics while correcting the shape error by the electromagnet actuator using the technique of the above-mentioned document, the heat generated from the electromagnet actuator causes unintended deformation of the mirror and new optical Aberrations can occur.

An object of the present invention is, for example, to provide an optical device capable of correcting the shape with high accuracy by suppressing heat generation accompanying the shape correction of the optical element.

In order to solve the above problems, an optical device according to one aspect of the present invention is an optical device that deforms a reflective surface of an optical element, and a base plate disposed apart from the surface on the opposite side of the reflective surface A correction unit including: a first permanent magnet attached to the surface opposite to the reflecting surface; and a second permanent magnet disposed at a position facing the first permanent magnet of the base plate The correction unit corrects the shape of the reflecting surface by a repulsive force or an attractive force generated by the first permanent magnet and the second permanent magnet.

According to the present invention, for example, it is possible to provide an optical device capable of correcting the shape with high accuracy by suppressing the heat generation accompanying the shape correction of the optical element.

FIG. 1 is a view showing a schematic configuration of an exposure apparatus according to a first embodiment. It is a sectional view showing a schematic structure of an optical device concerning a 1st embodiment. FIG. 1 is a front view showing a schematic configuration of an optical device according to a first embodiment. It is sectional drawing which shows schematic structure of the optical apparatus which concerns on 2nd Embodiment. It is a front view which shows schematic structure of the optical apparatus which concerns on 2nd Embodiment.

FIG. 1 is a view 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 which can move while holding the mask 55, and a substrate stage PS which can move while holding the substrate 56. The exposure apparatus 50 also includes a control unit 51 that controls the process of exposing the substrate 56.

The light emitted from the light source (not shown) included in the illumination optical system IL forms, for example, an arc-shaped illumination area long in the Y direction on the mask 55 by a slit (not shown) included in the illumination optical system IL. can do. The mask 55 and the substrate 56 are held by the mask stage MS and the substrate stage PS, respectively, and are at a substantially optically conjugate position (the position of the object plane and the image plane of the projection optical system UM) via the projection optical system UM. Be placed. The projection optical system UM has a predetermined projection magnification (for example, 1⁄2), 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 surface of the projection optical system UM (for example, the X direction in FIG. 1) at a speed ratio corresponding to the projection magnification of the projection optical system UM. Thereby, the pattern formed on the mask 55 can be transferred to the substrate 56.

The projection optical system UM is configured to include, for example, a plane mirror 52, a mirror 1 which is a concave mirror, and a convex mirror 54, as shown in FIG. The exposure light emitted from the illumination optical system IL and transmitted through the mask 55 has its optical path bent by the first surface 52 a of the plane mirror 52 and enters the first surface 1 a 1 of the mirror 1. The exposure light reflected on the first surface 1 a 1 of the mirror 1 is reflected on the convex mirror 54 and is incident on the second surface 1 a 2 of the mirror 1. The exposure light reflected by the second surface 1 a 2 of the mirror 1 is bent along the optical path by the second surface 52 b of the plane mirror 52 and forms an image on the substrate 56.

First embodiment

Next, the optical device 10 according to the first embodiment and the method of correcting the shape error will be described with reference to FIGS. 2 and 3. The optical device 10 is, for example, a large aperture concave mirror device used in a reflection mirror type exposure device. FIG. 2 is a cross-sectional view of the 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 reflective surface 1 a that reflects light and a back surface 1 b that is the surface opposite to the reflective surface. The mirror 1 is fixed to the base plate 5 via a fixing member 6. The base plate 5 is spaced apart on the back surface 1b.

The correction unit 2 is disposed between the mirror 1 and the base plate 5, and the first permanent magnet (mirror side magnet) 3 on the mirror side disposed on the back surface 1 b of the mirror 1 and the base side disposed on the opposing base plate 5 The second permanent magnet (base-side magnet) 4 of FIG. The correction unit 2 can generate a suction force or a repulsive force by inverting and installing the polarity of the base-side magnet 4 facing the mirror-side magnet 3. Further, by adjusting the inter-magnet distance between the mirror-side magnet 3 and the base-side magnet 4 facing the mirror-side magnet 3 using the adjustment mechanism 13, the amount of generated force can be adjusted. Specifically, the distance between the magnets is adjusted by adjusting the position where the base-side magnet 4 is disposed by the adjustment mechanism 13. Although the case of changing the polarity of the base-side magnet 4 has been described in the present embodiment, the present invention is not limited to this, and the attraction force and the repulsive force may be switched by changing the polarity of the mirror-side magnet 3.

Next, a method of correcting the shape error of the mirror 1 using the correction unit 2 will be described. The shape of the reflective surface 1a of the mirror 1 is measured using the measurement unit 12, and the direction and amount of force (shape error) required to correct the error of the shape are calculated. The measurement unit 12 is configured of a measurement instrument that measures the shape of the reflection surface 1 a of the mirror 1, such as a laser interferometer or a Shack-Hartmann sensor.

The polarity of the base-side magnet 4 of each correction unit 2 is selected according to the positive / negative (concave / convex) of the shape error indicating the direction and amount of force required to correct the error of the shape, and either attraction or repulsion To generate According to the size of the shape error, 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 to adjust the generated force. The plurality of correction units 2 partially generate tensile stress or compressive stress on the mirror 1. Therefore, the mirror surface 1a is partially elastically deformed according to the tensile stress or the compressive stress, and the shape error of the mirror surface 1a is corrected. In the optical device 10 according to the present embodiment, the shape error of the mirror 1 can be corrected without the heat generated by the shape correction mechanism due to the correction unit 2 configured by the permanent magnet.

Next, the arrangement of the correction unit 2 will be described with reference to FIG. FIG. 3 is a front view looking at the optical device 10 in the direction of arrow A in FIG. The correction units 2 are disposed at four locations at 90 ° intervals on the same circumference, and at eight locations at 45 ° intervals on another further outer circumference. However, the arrangement of the correction unit 2 is not limited to this, and the number and arrangement may be changed according to the optical aberration to be corrected.

The optical device of this embodiment can be variously modified without departing from the scope of the invention. For example, the number, arrangement, and the like of the correction units 2 can be set arbitrarily. Further, although the outer peripheral portion of the mirror 1 is fixed to the base plate 5 by the fixing member 6, any part of the mirror 1 may be fixed to the base plate 5 by the fixing member 6. Further, means such as screws or adhesion may be adopted for connecting the mirror 1 and the base plate 5. In the first embodiment, an example in which a spherical mirror having a circular concave surface is used as the mirror 1 has been described. However, the present invention is not limited thereto. For example, a flat mirror or a spherical mirror having a convex surface may be used as the mirror 1. The measuring unit 12 has been described by way of example of a sensor that measures the surface shape, but a sensor array configured of a plurality of displacement sensors that measure a plurality of positions of the mirror 1 may be used.

Second embodiment

Next, an optical device 20 according to a second embodiment and a method of correcting a shape error will be described with reference to FIGS. 4 and 5. In FIG. 4 and FIG. 5, the members common to the first embodiment are given the same reference numerals, and the description thereof will be omitted. FIG. 4 is a cross-sectional view of the optical device according to the second embodiment. The optical device 20 is, for example, a large-diameter concave mirror device used for a reflection mirror type exposure device, and can be applied to the mirror 1 in the exposure device of FIG. The optical device 20 according to the second embodiment corrects, for example, the optical aberration of the projection optical system, the magnification and distortion of the projection image, and the focus by deforming the reflection surface 1a of the mirror 1 included in the projection optical system of the exposure apparatus. Do. 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 includes 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 1 b of the mirror 1. The actuator 7 has a mover magnet 8 fixed to the back surface 1 b and a stator coil 9 fixed to the base plate 5. The displacement sensor 14 measures the distance to the back surface 1 b of the mirror 1. Based on the measurement value of the displacement sensor 14, the control command value of the actuator 7 is calculated by the control unit 11, and a desired force is generated. Thereby, the reflection surface 1a of the mirror 1 can 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.

The optical device 20 also has a correction unit 2. The correction unit 2 is arranged between the mirror 1 and the base plate 5 and is composed of the mirror side magnet 3 disposed on the back surface 1 b of the mirror 1 and the base side magnet 4 disposed on the base plate 5 facing the mirror 1. The shape correction method by the correction unit 2 is the same as that of the first embodiment. For the measurement of the shape error, the measurement unit 12 may be used as in the first embodiment, or the displacement sensor 14 may be used.

If a shape error due to an assembly error or a processing error of the mirror 1 is corrected by each of the actuators 7, it is necessary to continuously continuously provide a necessary force according to the shape error, so the heat generation becomes large. Brings unintended deformations to However, by correcting the shape error due to the assembly error or the processing error using the correction unit 2, it is possible to correct the shape error due to the assembly error or the processing error without generating heat. As a result, since each actuator only needs to generate a force necessary for the deformation drive amount required to correct the optical aberration in the projection optical system UM, heat generation can be relatively suppressed. Furthermore, in the optical device 20 that generally performs deformation drive with a plurality of actuators as in the second embodiment, the processing accuracy required for the mirror 1 is high, but the processing error can be corrected by the correction unit 2 Therefore, processing time and processing 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. FIG. 5 is a front view looking at the optical device 20 in the direction of arrow B in FIG. In the second embodiment, the correction unit 2 and the actuator 7 are respectively arranged at four locations at 90 ° intervals on the same circumference, and another 8 locations at 45 ° intervals on another outer circumference. ing. However, the arrangement of 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 the second embodiment, the central portion of the mirror 1 is fixed to the base plate 5 by the fixing member 6, but any 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 non-contact type actuator such as a voice coil motor (VCM) including the mover magnet 8 and the stator coil 9 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 with the correction unit configured by the permanent magnet, without generating heat accompanying the shape correction as shown in the first embodiment, or the second embodiment As shown in the above, it is possible to suppress heat generation and perform shape correction with high accuracy. In the above embodiment, an example of application to an exposure apparatus has been described, but an apparatus to which the optical device according to the above embodiment can be applied forms, for example, a latent image pattern of resist on a substrate by irradiation with EUV light. There is a lithographic apparatus. In addition, the present invention is applicable to a laser processing apparatus, a fundus imaging apparatus, a telescope, and the like.

Embodiment according to a method of manufacturing an article

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

Although 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 are possible within the scope of the present invention.

1 mirror 2 correction unit 3 mirror side magnet 4 base side magnet 5 base plate

Claims

An optical device for deforming a reflection surface of an optical element, comprising:
A base plate spaced apart on a surface opposite to the reflective surface;
The correction unit includes: a first permanent magnet attached to the surface opposite to the reflecting surface; and a second permanent magnet disposed at a position facing the first permanent magnet of the base plate ,
The optical device according to claim 1, wherein the correction unit corrects the shape of the reflection surface by a repulsive force or a suction force generated by the first permanent magnet and the second permanent magnet.
The optical device according to claim 1, wherein the repulsive force and the attractive force are switched by changing the polarity of the second permanent magnet.
The optical device according to claim 2, wherein the polarity of the second permanent magnet is changed based on a shape error measured by a measurement unit that measures the shape of the reflection surface.
4. The apparatus according to claim 1, further comprising an adjusting mechanism for adjusting a distance between the first permanent magnet and the second permanent magnet by adjusting a position of the second permanent magnet. The optical device according to any one of the items.
5. The optical device according to claim 4, wherein the adjustment mechanism adjusts the position of the second permanent magnet based on a shape error measured by a measurement unit that measures the shape of the reflection surface.
The actuator according to any one of claims 1 to 5, further comprising an actuator including a magnet attached to a surface opposite to the reflecting surface, and a coil disposed at a position facing the magnet on the base plate. An optical device according to item 1.
The optical device according to claim 6, further comprising a displacement sensor disposed on the base plate and measuring a distance between the base plate and a surface opposite to the reflection surface.
The optical device according to claim 7, wherein the actuator is driven based on the distance measured by the displacement sensor.
An exposure apparatus comprising the optical device according to any one of claims 1 to 8.
Exposing the substrate using the exposure apparatus according to claim 9;
And b. Developing the exposed substrate.