JP2023005712A - Projection optical system, exposure device, and method for manufacturing article - Google Patents

Abstract

To provide a projection optical system advantageous for achieving high NA, low aberration, and a large screen.SOLUTION: A projection optical system 7 reflects light from an arcuate area of an object surface 2 in order of a first plane mirror 41, a first concave mirror 31, a convex mirror 5, a second concave mirror 31, and a second plane mirror 42 and forms the light into an image on an image surface 6. An optical path between the object surface and the first plane mirror and an optical path between the second plane mirror and the image surface are parallel to a first direction. An optical path between the first plane mirror and the first concave mirror and an optical path between the second concave mirror and the second plane mirror is parallel to a second direction orthogonal to the first direction. The width in the second direction of the arcuate area, the radii of curvature of the first concave mirror and the second concave mirror, the numerical aperture sinφ of the projection optical system, the minimum distance and the maximum distance along the second direction between the arcuate area and an optical axis of the projection optical system, and a distance L along the first direction between the object surface and the image surface satisfy predetermined conditional expressions.SELECTED DRAWING: Figure 1

Description

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

Devices such as semiconductor devices and flat panel displays (FPDs) are manufactured through a photolithography process. In the photolithography process, a pattern of an original (mask or reticle) is projected onto a substrate (glass plate or wafer) coated with a photosensitive agent (resist) through a projection optical system including optical members such as lenses and mirrors. , including an exposure step for exposing such a substrate.

As a projection optical system used in such an exposure process, there has been proposed a projection optical system that forms an image of an original pattern on a substrate at the same magnification using an off-axis ring-shaped good image area (Patent Document 1). and 2). Such a projection optical system has a first plane mirror, a first concave mirror, a convex mirror, a second concave mirror and a second plane mirror, which are arranged in order on an optical path from an object plane to an image plane.

JP 2011-039172 A JP 2006-078631 A

A projection optical system is required to have high optical performance, that is, high NA and low aberration in order to project fine patterns of the original with good reproducibility. In addition, the projection optical system is required to have a large screen for efficient mass production of devices.

However, in the projection optical systems disclosed in Patent Documents 1 and 2, the screen sharply curves along the ring zone as the screen size increases. As a result, the two plane mirrors (the first plane mirror and the second plane mirror) are brought close to each other, making it difficult to manufacture the plane mirrors. In order to avoid this, the diameter of the annular good image area must be increased to moderate the curvature of the screen. However, increasing the diameter of the annular good image area causes the following problems.

First, as the diameter of the annular good image area increases, the size of the concave mirror increases, making it difficult to manufacture the concave mirror. There is also the problem of interference between the stage holding the original and the concave mirror. Secondly, as the diameter of the annular good image area increases, the residual aberration of the projection optical system increases, deteriorating the optical performance.

Therefore, the projection optical system must satisfy the following (1), (2), (3) and (4).
(1) Separation of the two plane mirrors (upper and lower trapezoidal mirror surfaces) must be ensured (2) The diameter (size) of the concave mirror must be within the manufacturable range (3) The difference between the concave mirror and the object plane (mask plane) (4) The optical performance is within the allowable range. It is an exemplary object to provide a projection optical system.

In order to achieve the above object, a projection optical system as one aspect of the present invention directs light from an arcuate region on an object plane to a first plane mirror, a first concave mirror, a convex mirror, a second concave mirror, and a second plane mirror in that order. A projection optical system that reflects and forms an image on an image plane, wherein an optical path between the object plane and the first plane mirror and an optical path between the second plane mirror and the image plane are directed in a first direction and an optical path between the first plane mirror and the first concave mirror and an optical path between the second concave mirror and the second plane mirror are parallel to a second direction orthogonal to the first direction wherein SW is the width of the arcuate region in the second direction, R is the radius of curvature of the first concave mirror and the second concave mirror, sinφ is the numerical aperture of the projection optical system, and the arcuate region and the projection optical system are Let Y1 and Y2 be the minimum and maximum distances along the second direction, respectively, between the optical axis of the system and L be the distance along the first direction between the object plane and the image plane, T1 is the value required to separate the first plane mirror and the second plane mirror, T2 is the value required for the diameters of the first concave mirror and the second concave mirror, and the first concave mirror and the object plane , and T4 is the value required for the image height ratio to the radius of curvature of the first concave mirror and the second concave mirror. −tanφ)>T1, Y2+R·tanφ<T2, L/2−(Y2+R·tanφ)>T3, and (Y2−SW/2)<T4.

Further objects or other aspects of the present invention will be made clear by the embodiments described below with reference to the accompanying drawings.

According to the present invention, for example, it is possible to provide a projection optical system that is advantageous in realizing a high NA, low aberration, and large screen.

1 is a schematic diagram showing the configuration of a projection optical system as one aspect of the present invention; FIG. FIG. 4 is a diagram showing a screen area on an object plane; 2 is a diagram showing some of the elements of the projection optical system shown in FIG. 1; FIG. 2 is a diagram showing some of the elements of the projection optical system shown in FIG. 1; FIG. 2 is a diagram showing some of the elements of the projection optical system shown in FIG. 1; FIG. It is a figure which shows the cross section shown in FIG. 5 from the +Y side. 7 is a diagram showing an XY cross section including the optical axis shown in FIG. 6 from the +Z side; FIG. 4 is a diagram showing possible ranges of the radius of the outer periphery of the good image area and the radius of curvature of the concave mirror in Example 1. FIG. 4 is a ray diagram of the projection optical system in Example 1. FIG. FIG. 10 is an aberration diagram of the projection optical system shown in FIG. 9; FIG. 10 is a diagram showing possible ranges of the radius of the outer circumference of the good image area and the radius of curvature of the concave mirror in Example 2; FIG. 10 is a ray diagram of the projection optical system in Example 2; FIG. 13 is an aberration diagram of the projection optical system shown in FIG. 12; FIG. 10 is a diagram showing possible ranges of the radius of the outer circumference of the good image area and the radius of curvature of the concave mirror in Example 2; 6 is a diagram showing the cross section shown in FIG. 5 from the +Y side in Example 3. FIG. 16 is a diagram showing an XY cross section including the optical axis shown in FIG. 15 in Example 3. FIG. 16 is a diagram showing a YZ cross section including the optical axis shown in FIG. 15 in Example 3. FIG. FIG. 10 is a diagram showing possible ranges of the radius of the outer circumference of the good image area and the radius of curvature of the concave mirror in Example 3; FIG. 11 is a ray diagram of a projection optical system in Example 3; FIG. 20 is an aberration diagram of the projection optical system shown in FIG. 19; 1 is a schematic diagram showing the configuration of an exposure apparatus as one aspect of the present invention; FIG.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In addition, the following embodiments do not limit the invention according to the scope of claims. Although multiple features are described in the embodiments, not all of these multiple features are essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant description is omitted.

FIG. 1 is a schematic diagram showing the configuration of a projection optical system 7 as one aspect of the present invention. The projection optical system 7 is an optical system based on the Offner optical system. The projection optical system 7 has a concave mirror 3 , a trapezoidal mirror 4 , a convex mirror 5 , an aspherical lens 11 and a meniscus lens 13 . The projection optical system 7 forms (images) an image of the object plane 2 on an image plane 6 separated by a distance L along the Z direction.

In FIG. 1, PA1 indicates the optical axis of the projection optical system 7. As shown in FIG. PA2 indicates the optical axis of the projection optical system 7 bent by 90 degrees due to the reflection on the trapezoidal mirror 4. FIG.

The concave mirror 3 has a reflecting surface 31 (first concave mirror and second concave mirror) with a radius of curvature R on its surface. In this embodiment, as shown in FIG. 1, the first concave mirror and the second concave mirror are composed of one mirror, that is, the concave mirror 3 (reflecting surface 31). may be composed of separate mirrors.

The trapezoidal mirror 4 has, on its surfaces, an upper reflecting surface 41 (first plane mirror) inclined by 45 degrees with respect to the optical axis PA1, and a lower reflecting surface 42 (second plane mirror) inclined by 45 degrees with respect to the optical axis PA1. plane mirror). An intersection point Pt between the optical axis PA1 and the optical axis PA2 is located on the same plane as the reflecting surface 41 and the same plane as the reflecting surface 42 . A flat-pressing portion 43, which is a surface sandwiched between the reflecting surfaces 41 and 42, is not an optical surface, but is an area that affects the manufacturing process of the trapezoidal mirror 4, as will be described later. Instead of the trapezoidal mirror 4, the reflecting surfaces 41 and 42 may be configured as separate plane mirrors.

The aspherical lens 11 is a lens having an aspheric upper surface and a flat lower surface. The aspherical lens 12 is a lens having a flat upper surface and an aspherical lower surface. The meniscus lens 13 is a lens that has one surface as a concave surface and the other surface as a convex surface. As will be described later in Examples 2 and 3, the surface of the meniscus lens 13 can also be made aspherical.

A convex mirror 5 is positioned at the pupil of the projection optical system 7 . The projection optical system 7 is an optical system that is vertically symmetrical (object side and image side) with the convex mirror 5 interposed therebetween. The NA (numerical aperture) of the projection optical system 7 is represented by NA=sin φ, where φ is the divergence angle of light rays.

The projection optical system 7 is a double-telecentric optical system, and its principal rays are parallel to the Z-axis on both the object plane side and the image plane side. The imaging magnification of the projection optical system 7 is substantially -1.

In the projection optical system 7, the optical path between the object plane 2 and the reflecting surface 41 of the trapezoidal mirror 4 and the optical path between the reflecting surface 42 of the trapezoidal mirror 4 and the image plane 6 are in the Z direction (first direction). is parallel to The optical path between the reflecting surface 41 of the trapezoidal mirror 4 and the concave mirror 3 and the optical path between the concave mirror 3 and the reflecting surface 42 of the trapezoidal mirror 4 are in the Y direction (second direction orthogonal to the first direction). is parallel to

FIG. 2 is a diagram showing a screen area 24 on the object plane 2. As shown in FIG. As shown in FIG. 2, the projection optical system 7, as shown in FIG. 2, has an outer circumference radius Y2, It has an annular good image area 23 (arc-shaped area) with a width SW.

The screen area 24 is inscribed in the outer circumference of the good image area 23 and has an arcuate width (hereinafter referred to as "screen width") VS in the X direction and a width (hereinafter referred to as "slit width") SW in the Y direction. area. The screen area 24 is projected onto the image plane 6 via the projection optical system 7 .

Here, in the screen area 24, the point with the shortest distance in the Y direction from the optical axis PA1 is P1, and the distance (minimum distance) is Y1. In the screen area 24, there are two points having the shortest distance in the Y direction from the optical axis PA1, a point on the +X side (lower left end) and a point on the −X side (lower right end). Here, the point on the +X side is adopted because even if it is adopted, it does not affect the following discussion. Similarly, in the screen area 24, the point with the longest distance in the Y direction from the optical axis PA1 is P2, and the distance (maximum distance) is Y2. Since the screen area 24 is inscribed in a circle with a radius of Y2, it satisfies the relationship shown in the following formula (1).

In order to establish the configuration of the projection optical system 7, the following four conditions must be satisfied.
Condition (1): Separation between the upper reflecting surface 41 and the lower reflecting surface 42 of the trapezoidal mirror 4 Condition (2): The diameter of the concave mirror 3 is within a manufacturable range Condition ( 3): The separation between the concave mirror 3 and the object plane 2 is ensured Condition (4): The optical performance is within the permissible range Details of conditions (1) to (4) and conditions ( A method for concretely formulating the conditional expressions for satisfying the conditions 1) to (4) will be explained. Furthermore, a method for specifically formulating a conditional expression for satisfying the condition (5): that an arrangement area for the holding structure of the convex mirror 5 is ensured will also be described.

In the following description, refraction of light rays in the aspherical lenses 11 and 12 is ignored. This is because the thickness of the aspherical lenses 11 and 12 is sufficiently thin and the aspherical shape is minute, so that the refraction of rays can be substantially ignored in the following discussion.

Condition (1) will be described with reference to FIG. Only some of the elements of the projection optical system 7 are shown in FIG. As shown in FIG. 3, the distance between the object plane 2 and the optical axis PA2 is defined as dt. As described above, the projection optical system 7 is a vertically symmetrical optical system with the convex mirror 5 interposed therebetween. Therefore, since the distance between the optical axis PA2 and the image plane 6 is also equal to dt, the following equation (2) holds.
dt=L/2 (2)
where L is the distance between the object plane 2 and the image plane 6 .

A light ray L1 is a light ray most incident on the +Y side of the reflecting surface 41 among the light rays emitted from the point P1 on the object plane 2 . Since the point P1 is the most +Y side point in the screen area 24, the ray L1 is the most +Y side ray in the optical path from the object surface 2 to the reflecting surface 41 among the rays emitted from the screen area 24. is.

A point P3 is a point at which the light ray L1 is incident on the reflecting surface 41 . Here, the distance from the optical axis PA1 to the point P3 is defined as tr. As shown in FIG. 3, when the point P3 exists on the -Y side of the optical axis PA1, the sign of tr is defined as positive. Therefore, when the point P3 exists on the +Y side of the optical axis PA1, the sign of tr is negative.

Since the reflecting surface 41 has an angle of 45 degrees with respect to the optical axis PA1, the distance between the optical axis PA2 and the point P3 is equal to tr. Therefore, the distance between the object plane 2 and the point P3 is (dt−tr), and the distance in the Y direction between the points P1 and P3 is represented by (dt−tr)·tanφ. , the relationship shown in the following equation (3) is established.
tr=Y1−(dt−dr)·tanφ (3)
By rearranging tr and using the formula (2), the relationship shown in the following formula (4) is established.
tr=(Y1−L/2·tanφ)/(1−tanφ) (4)
As can be seen from Figure 3, tr must be greater than zero. If tr is less than zero, that is, if the point P3 exists on the optical axis PA1 or on the right side (+Y side) of the optical axis PA1, the trapezoidal mirror 4 cannot be formed. Therefore, the relationship shown in the following equation (5) is required.
(Y1-L/2 tan φ)/(1-tan φ)>0 (5)
Note that the relationship shown in Equation (5) is also required when two separate plane mirrors are used instead of the trapezoidal mirror 4. FIG.

Furthermore, from the viewpoint of the manufacturing process of the trapezoidal mirror 4, the shape of the trapezoidal mirror 4 is restricted. For example, when tr is small, the reflecting surface 41 and the reflecting surface 42 of the trapezoidal mirror 4 are close to each other, and the flat pressing portion 43 becomes small. The width of the flat pressing portion 43 is represented by 2·tr. If the width of the flat-pressing portion 43 is too small, there is a high possibility that the edge will be chipped in the polishing process of the trapezoidal mirror 4 . The width of the flat pressed portion 43 is desirably greater than 80 mm so that the shape of the component can be practically ground. Therefore, it is preferable to satisfy the relationship shown in the following formula (6).
(Y1-L/2・tanφ)/(1-tanφ)>40mm (6)
Next, condition (2) will be described with reference to FIG. Only some of the elements of the projection optical system 7 are shown in FIG. In FIG. 4, surface 2′ is the surface that is optically equivalent to object surface 2 without reflective surface 41. In FIG. A point P'2 is a point on the plane 2' corresponding to the point P2. The distance between plane 2' and optical axis PA1 is dt, which is equal to the distance between plane 2 and optical axis PA2.

Here, the distance between the surface 2' and the concave mirror 3 is d'o. If do is the sum of the distance between the object plane 2 and the point Pt and the distance between the point Pt and the concave mirror 3, then d'o=do.

Furthermore, d'o=do is approximately equal to the radius of curvature R of the concave mirror 3. This is a requirement for optical performance, and if do deviates significantly from R, curvature of field and astigmatism will be larger than permissible values, making it impossible to satisfy the requirement for optical performance.

Here, let us consider the light ray L2 that is most incident on the +Z side of the concave mirror 3 among the light rays emitted from the point P2. A point P5 is an intersection point between the light ray L2 and the reflecting surface 31 of the concave mirror 3 . A point P6 is an intersection point between the optical axis PA2 and the reflecting surface 31 of the concave mirror 3 .

As shown in FIG. 4, the distance between point P5 and optical axis PA2 is defined as EAo/2. The curvature of the concave mirror 3 is exaggerated in FIG. However, in reality, the radius of curvature R of the reflecting surface 31 of the concave mirror 3 is sufficiently large with respect to the distance between the point P4 and the optical axis PA2 and the distance between the point P5 and the optical axis PA2. , P4, P5 and P6 can be neglected. Therefore, the distance between the point P'2 and the point P4 can be regarded as d'o, that is, R, so the relationship shown in the following formula (7) is established.
EAo/2≈Y2+d′o·tanφ≈Y2+R・tanφ (7)
In order to configure the reflecting surface 31 on the concave mirror 3, the diameter D of the concave mirror 3 should be twice EAo/2, ie larger than EAo. However, if D is too large, manufacturing of the concave mirror 3 becomes difficult. A low thermal expansion ceramic is generally used as the base material of the concave mirror 3, and there is a limit to the size of equipment such as a sintering furnace used in the manufacturing process. Also, there is a limit to the size of a polishing machine used in the process of polishing a base material to produce a reflecting surface. Therefore, a concave mirror 3 having a diameter D greater than or equal to a certain value cannot be manufactured, or cannot be manufactured practically because the manufacturing cost is extremely high. In order to be practically manufacturable, D must be smaller than 6000 mm, so the relationship shown in the following equation (8) is required.
Y2+R・tanφ<3000mm (8)
Further, since the manufacturing cost of the concave mirror 3 having a diameter D of 2400 mm or more is extremely high, it is desirable that D is smaller than 2400 mm, and the relationship shown in the following equation (9) is required.
Y2+R・tanφ<1200mm (9)
Next, condition (3) will be described with reference to FIG. As shown in FIG. 4, the distance in the Z direction between point P5 and object plane 2 is defined as dm. The sign of dm is positive when the object plane 2 exists above the point P5 (+Z direction).

When the projection optical system 7 is mounted on an exposure apparatus, the original placed at the position of the object plane 2 and the substrate placed at the position of the image plane 6 are synchronously scanned to perform an exposure operation (scanning exposure). I do. In scanning exposure, the original positioned at the object plane 2 is driven in the Y direction.

For example, when dm≦0, that is, when the point P5 exists above the object plane 2, driving the original in the +Y direction interferes with the concave mirror 3, making scanning exposure impossible. Therefore, L/2−(Y2+R·tanφ)>0 (10), which requires the relationship shown in the following equation (10)
As an actual configuration, the original is generally held on an original stage, and scanning exposure is performed by driving the original stage in the Y direction. The original plate stage has a thickness of at least about 200 mm or more, and holds the original plate from below. Therefore, in order to configure the original stage, the distance dm between the object plane 2 and the point P5 must be equal to or greater than the thickness required for the original stage. Therefore, since the distance between the reflecting surface 31 of the concave mirror 3 and the object plane 2 must be greater than 200 mm, the relationship shown in the following equation (11) is required.
L/2-(Y2+R・tanφ)>200mm (11)
Next, condition (4) will be described. As described above, due to the characteristics of the Offner optical system, which is the basis of the projection optical system 7, the optical performance is degraded depending on the diameter of the annular zone of the good image area 23. FIG. As shown in FIG. 2, when the distance between the intermediate position of the annular zone of the good image area 23 and the optical axis PA1 is H, the relationship shown in the following formula (12) is established.
H=Y2-SW/2 (12)
As a result of intensive studies, the present inventors found that the ratio of H to the radius of curvature R of the concave mirror 3 (image height ratio) needs to be less than 0.3.
(Y2−SW/2)<0.3 (13)
Furthermore, as a result of intensive studies, the inventors of the present invention have found that the ratio of H to the radius of curvature R of the concave mirror 3 is preferably less than 0.22 in terms of optical performance, as represented by the following equation (14). I found out.
(Y2−SW/2)<0.22 (14)
Finally, condition (5) will be described with reference to FIGS. 5, 6 and 7. FIG. Only some of the elements of the projection optical system 7 are shown in FIG. In FIG. 5, surface 2′ is a surface that is optically equivalent to object surface 2, as in FIG. A point P'1 is a point on the surface 2' corresponding to the point P1. A cross section 51 is a plane that passes through the vertex of the convex mirror 5 and is perpendicular to the Y axis. The distance between the surface 2' and the convex mirror 5, ie the distance between the surface 2' and the section 51 is defined as dv. Due to the optical performance requirements of the Offner optical system, dv is approximately equal to half the radius of curvature R of the concave mirror 3, ie, R/2.

Here, let us consider a ray L3 that is incident on the reflecting surface 31 of the concave mirror 3 at a position on the -Z side among the rays emitted from the point P1. A point P9 is the intersection of the ray L3 and the cross section 51 . If the distance in the Z direction between the point P and the optical axis PA2 is defined as V/2, V/2 is represented by the following equation (15).
V/2=Y1-dv.tanφ≈Y1-R/2.tanφ (15)
FIG. 6 is a diagram showing the cross section 51 from the +Y side. In FIG. 6, LR1 is an area through which the light reflected by the upper reflecting surface 41 of the trapezoidal mirror 4 passes on the way to the concave mirror 3 . LR2 is an area through which the light reflected by the convex mirror 5 and reflected by the concave mirror 3 passes on the way to the lower reflecting surface 42 of the trapezoidal mirror 4 . The holding structure 72 is a structure for holding the convex mirror 5 and the meniscus lens 13 .

FIG. 7 is a diagram showing an XY cross section including the optical axis PA2 from the +Z side (upper side). The surroundings of the convex mirror 5 and the meniscus lens 13 are fixed to a holding structure 72 via, for example, a clamping mechanism or fitting structure. The holding structure 72 is fixed to the lens barrel 71 via a portion extending in the X direction (third direction orthogonal to the first direction and the second direction). The lens barrel 71 is a structure (holding member) for covering and stably holding the entire projection optical system 7 .

Referring to FIG. 6, the regions LR1 and LR2 are closest to each other in the vicinity of the point P9, and the distance is V between them. If the holding structure 72 interferes with the regions LR1 and/or LR2, vignetting will occur in the light beam. Therefore, the distance V between region LR1 and region LR2 must be greater than the width of retaining structure 72 in the Z direction. On the other hand, if there is no space between the region LR1 and the region LR2, that is, if V≦0, the holding structure 72 cannot be constructed. Therefore, the relationship shown in the following equation (16) is required.
Y1−R/2·tanφ>0 (16)
Furthermore, from the viewpoint of mechanical rigidity, it is preferable that the thickness of the holding structure 72 in the Z direction is at least 20 mm or more.
Y1-R/2・tanφ>20mm (16)
Summarizing these conditions, the following conditional expressions J1 to J5 are obtained as conditional expressions for satisfying the conditions (1) to (5).
Condition (1): J1=(Y1−L/2·tanφ)/(1−tanφ)>T1
Condition (2): J2=Y2+R·tan φ<T2
Condition (3): J3=L/2-(Y2+R・tanφ)>T3
Condition (4): J4=(Y2-SW/2)<T4
Condition (5): J5=Y1−R/2·tanφ>T5
Note that T1 to T5 are threshold values.
The threshold value T1 is a value required to separate the reflecting surface 41 (first plane mirror) and the reflecting surface 42 (second plane mirror) of the trapezoidal mirror 4 .
The threshold value T2 is a value required for the diameter of the concave mirror 3 (the first concave mirror and the second concave mirror).
The threshold T3 is a value required to separate the concave mirror 3 (first concave mirror) and the object plane 2 .
The threshold value T4 is a value required for the image height ratio to the radius of curvature of the concave mirror 3 (the first concave mirror and the second concave mirror).
The threshold T5 is a value required to secure an area (placement area) for arranging the holding structure 72 .

Examples of the optical system (projection optical system) satisfying the conditions (1) to (5) are shown below.

<Example 1>
In this example, the NA of the optical system, that is, sin φ, is 0.12 and the dominant wavelength is 320 nm. The total length of the optical system, ie the distance L between the object plane 2 and the image plane 6, is 3000 mm. The slit width SW is 100 mm and the screen width VS is 1200 mm.

In this example, T1=40 mm, T2=200 mm, T3=1200 mm, T4=0.22, and T5=20 mm are selected.

FIG. 8 is a diagram showing possible ranges of the radius Y2 of the outer circumference of the good image area 23 and the radius of curvature R of the concave mirror 3 in this embodiment. Referring to FIG. 8, the shaded area corresponds to the area satisfying all conditions (1) to (5). In this embodiment, Y2=710 mm and R=4000 mm, which are included in the hatched area shown in FIG. 8, are selected.

FIG. 9 is a ray diagram of the projection optical system 1001 designed based on the above policy. FIG. 10 is an aberration diagram of the projection optical system 1001. FIG. The specifications of the projection optical system 1001 are shown in Table 1 below, and the values of conditional expressions J1 to J5 at that time are shown in Table 2 below.

<Example 2>
In this example, the NA of the optical system, ie sinφ, is 0.11 and the dominant wavelength is 320 nm. The total length of the optical system, ie the distance L between the object plane 2 and the image plane 6, is 3000 mm. The slit width SW is 100 mm and the screen width VS is 1400 mm.

The thresholds T1 to T5 in this embodiment are the same as in the first embodiment.

FIG. 11 is a diagram showing possible ranges of the radius Y2 of the outer circumference of the good image area 23 and the radius of curvature R of the concave mirror 3 in this embodiment. Referring to FIG. 11, the shaded area surrounded by straight lines J3, J4 and J5 is the area that satisfies all conditions (1) to (5). In this embodiment, Y2=814 mm and R=3480 mm, which are included in the hatched area shown in FIG. 11, are selected.

FIG. 12 is a ray diagram of the projection optical system 1002 designed based on the above policy. FIG. 13 is an aberration diagram of the projection optical system 1002. FIG. The specifications of the projection optical system 1002 are shown in Table 3 below, and the values of conditional expressions J1 to J5 at that time are shown in Table 4 below.

Incidentally, referring to FIG. 11, it can be seen that the design solution selected in this embodiment still has a margin with respect to conditions (1) and (5). This shows that even smaller values of Y1 are acceptable. In other words, it indicates that the screen width VS can be made larger.

FIG. 14 shows possible ranges of the radius Y2 of the outer circumference of the good image area 23 and the curvature radius R of the concave mirror 3 when the screen width VS is 1500 mm. The design solution selected in this example is still included in the area surrounded by straight lines J3, J4 and J5 even at VS = 1500 mm, and satisfies the conditions (1) to (5). there is Therefore, it is possible to use a larger screen width VS.

<Example 3>
In this example, the NA of the optical system, that is, sin φ, is 0.10 and the dominant wavelength is 320 nm. The total length of the optical system, ie the distance L between the object plane 2 and the image plane 6, is 1700 mm. The slit width SW is 100 mm and the screen width VS is 1200 mm.

In this example, T1=0 mm, T2=0 mm, T3=3000 mm, and T4=0.30 are selected.

FIG. 15 is a diagram showing a cross section 51 from the +Y side in this embodiment. As explained with reference to FIG. 6, LR1 is a region through which the light reflected by the reflecting surface 41 on the upper side of the trapezoidal mirror 4 passes on the way to the concave mirror 3, and LR2 is a region where the light is reflected by the convex mirror 5 and is an area through which the light reflected by . FIG. 16 is a diagram showing an XY cross section including the optical axis PA2 in this embodiment. FIG. 17 is a diagram showing a YZ section including the optical axis PA2 in this embodiment. In this embodiment, the holding structure 72 is fixed to the lens barrel 71 through a portion that penetrates the trapezoidal mirror 4 and extends in the Y direction. As a specific structure, for example, the structure disclosed in Japanese Patent No. 6386896 can be applied. In this embodiment, it is not necessary to secure a space (arrangement area) for arranging the holding structure 72 on the side (X direction) of the convex mirror 5 . Therefore, since it is not necessary to satisfy the condition (5), it is sufficient to satisfy the conditions (1) to (4).

FIG. 18 is a diagram showing possible ranges of the radius Y2 of the outer periphery of the good image area 23 and the radius of curvature R of the concave mirror 3 in this embodiment. Referring to FIG. 18, the shaded area is the area that satisfies all conditions (1) to (4). In this embodiment, Y2=630 mm and R=2150 mm, which are included in the hatched area shown in FIG. 18, are selected.

FIG. 19 is a ray diagram of the projection optical system 1003 designed based on the above policy. FIG. 20 is an aberration diagram of the projection optical system 1003. FIG. The specifications of the projection optical system 1003 are shown in Table 5 below, and the values of conditional expressions J1 to J5 at that time are shown in Table 6 below.

In this embodiment, the case where conditions (1) to (5) or conditions (1) to (4) are satisfied has been described, but the present invention is not limited to this. For example, if condition (1), condition (2), condition (4) and condition (5) are satisfied except condition (3), or if condition (1), condition (2) and condition (4) are satisfied It also constitutes an aspect of the invention if it does.

Next, the exposure apparatus 100 having the projection optical system 7 described above will be described. FIG. 21 is a schematic diagram showing the configuration of an exposure apparatus 100 as one aspect of the present invention. The exposure apparatus 100 is, for example, a lithography apparatus used in a device manufacturing process (photolithography process) to form a pattern on a substrate. The exposure apparatus 100 exposes the substrate through the original, and in this embodiment, exposes the substrate while scanning the original and the substrate (scanning exposure) to transfer the pattern of the original onto the substrate. It is a scanning type exposure device (scanner). However, the exposure apparatus 100 can adopt a step-and-repeat method or other exposure method.

The exposure apparatus 100 has an illumination optical system 1, an original stage 22, a projection optical system 7, and a substrate stage 62, as shown in FIG.

The exposure apparatus 100 irradiates the original 21 with light emitted from a light source (not shown) via the illumination optical system 1 . Thus, the illumination optical system 1 illuminates the original 21 with light from the light source. The lower surface of the original 21 is arranged on the object plane 2 of the projection optical system 7 covered by the lens barrel 71 . A pattern to be transferred to the substrate 61 is formed on the lower surface of the original 21 . The pattern of the original 21 is projected onto the substrate 61 via the projection optical system 7 . In this way, the projection optical system 7 images the light from the pattern of the original 21 onto the substrate 61 . A photosensitive agent (resist) is applied to the substrate 61, and the pattern of the original plate 21 is transferred to the substrate 61 through a developing process.

During exposure, the exposure apparatus 100 performs exposure (scanning exposure) while scanning the original stage 22 holding the original 21 and the substrate stage 62 holding the substrate 61 synchronously in the ±Y directions. The larger the screen width VS of the projection optical system 7, the larger the area of the pattern of the original 21 that is transferred onto the substrate 61 in one scanning exposure, so that the productivity of the exposure apparatus 100 can be improved. . Further, the energy of the light (exposure light) with which the substrate 61 is irradiated during the scanning exposure can be increased as the slit width SW of the projection optical system 7 is increased. Therefore, the time required for scanning can be shortened, and the productivity of the exposure apparatus 100 can be improved.

After the scanning exposure is completed, the substrate stage 62 is stepped in the X direction and/or the Y direction by a constant amount in order to transfer the pattern of the original plate 21 to another shot area (partial area) of the substrate 61 . When the scanning exposure for all shot areas (entire surface) of the substrate 61 is completed, the substrate 61 is unloaded from the exposure apparatus 100 and a new unexposed substrate is loaded into the exposure apparatus 100 .

Next, a method for manufacturing an article as one aspect of the present invention will be described. The method for manufacturing an article according to the present embodiment is suitable for manufacturing devices such as semiconductor devices and liquid crystal display devices. A semiconductor device is manufactured through a pre-process of forming an integrated circuit on a substrate and a post-process of completing the integrated circuit chip formed on the substrate in the pre-process as a product. The pre-process includes a process of exposing a substrate coated with a photosensitive agent using the exposure apparatus 100 described above and a process of developing the exposed photosensitive agent. The post-process includes an assembly process (dicing, bonding) and a packaging process (encapsulation). A liquid crystal display device is manufactured through a process of forming a transparent electrode. The process of forming the transparent electrode includes a process of applying a photosensitive agent to the glass substrate on which the transparent conductive film is deposited, a process of exposing the glass substrate coated with the photosensitive agent using the above-described exposure apparatus 100, and an exposure process. and developing the photosensitizer. The method for manufacturing an article according to the present embodiment is advantageous in at least one of performance, quality, productivity and production cost of the article as compared with conventional methods.

The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the claims are appended to make public the scope of the invention.

2: Object surface 3: Concave mirror 31: Reflecting surface 4: Trapezoidal mirror 41, 42: Reflecting surface 5: Convex mirror 6: Image surface 7: Projection optical system

Claims (21)

A projection optical system that reflects light from an arc-shaped area on an object surface in order of a first plane mirror, a first concave mirror, a convex mirror, a second concave mirror, and a second plane mirror to form an image on an image plane,
an optical path between the object plane and the first plane mirror and an optical path between the second plane mirror and the image plane are parallel to a first direction;
an optical path between the first plane mirror and the first concave mirror and an optical path between the second concave mirror and the second plane mirror are parallel to a second direction perpendicular to the first direction,
SW is the width of the arc-shaped area in the second direction, R is the radius of curvature of the first concave mirror and the second concave mirror, sin φ is the numerical aperture of the projection optical system, and the light of the arc-shaped area and the projection optical system Let Y1 and Y2 be respectively the minimum and maximum distances along the second direction between the axes, and L be the distance along the first direction between the object plane and the image plane,
T1 is the value required to separate the first plane mirror and the second plane mirror, T2 is the value required for the diameters of the first concave mirror and the second concave mirror, and the first concave mirror and the object plane Let T3 be the value required to separate , and T4 be the value required for the image height ratio to the radius of curvature of the first concave mirror and the second concave mirror,
(Y1−L/2·tanφ)/(1−tanφ)>T1,
Y2+R·tanφ<T2,
L/2-(Y2+R·tanφ)>T3,
(Y2-SW/2)<T4
A projection optical system characterized by satisfying 2. A projection optical system according to claim 1, wherein the magnification of said projection optical system is -1. further comprising a holding member that holds the convex mirror;
3. The projection optical system according to claim 1, wherein the holding member includes a portion extending in the second direction from between the first plane mirror and the second plane mirror toward the convex mirror. 4. The projection optical system according to claim 1, wherein said T1 is zero. 4. The projection optical system according to claim 1, wherein said T1 is 40 mm. 4. The projection optical system according to claim 1, wherein said T2 is 3000 mm. 4. The projection optical system according to claim 1, wherein said T2 is 1200 mm. 4. The projection optical system according to claim 1, wherein said T3 is zero. 4. The projection optical system according to claim 1, wherein said T3 is 200 mm. 4. The projection optical system according to claim 1, wherein said T4 is 0.3. 4. The projection optical system according to claim 1, wherein said T4 is 0.22. further comprising a holding member that holds the convex mirror;
3. The projection optical system according to claim 1, wherein said holding member includes a portion extending in a third direction orthogonal to said first direction and said second direction. Assuming that T5 is the value required to secure the area for arranging the holding member,
Y1−R/2・tanφ>T5
13. The projection optical system according to claim 12, wherein: 14. A projection optical system according to claim 13, wherein said T5 is zero. 14. A projection optical system according to claim 13, wherein said T5 is 20 mm. 16. The projection optical system according to any one of claims 1 to 15, wherein the first concave mirror and the second concave mirror are different mirrors. 16. The projection optical system according to any one of claims 1 to 15, wherein the first concave mirror and the second concave mirror are composed of one mirror. A projection optical system that reflects light from an arc-shaped area on an object surface in order of a first plane mirror, a first concave mirror, a convex mirror, a second concave mirror, and a second plane mirror to form an image on an image plane,
an optical path between the object plane and the first plane mirror and an optical path between the second plane mirror and the image plane are parallel to a first direction;
an optical path between the first plane mirror and the first concave mirror and an optical path between the second concave mirror and the second plane mirror are parallel to a second direction perpendicular to the first direction,
SW is the width of the arc-shaped area in the second direction, R is the radius of curvature of the first concave mirror and the second concave mirror, sin φ is the numerical aperture of the projection optical system, and the light of the arc-shaped area and the projection optical system Let Y1 and Y2 be respectively the minimum and maximum distances along the second direction between the axes, and L be the distance along the first direction between the object plane and the image plane,
T1 is the value required to separate the first plane mirror and the second plane mirror, T2 is the value required for the diameters of the first concave mirror and the second concave mirror, and the first concave mirror and the second concave mirror are Let T4 be the value required for the image height ratio to the radius of curvature of
(Y1−L/2·tanφ)/(1−tanφ)>T1,
Y2+R·tanφ<T2,
(Y2-SW/2)<T4
A projection optical system characterized by satisfying an illumination optical system that illuminates the original with light from a light source;
a projection optical system according to any one of claims 1 to 18, which projects the pattern of the original onto a substrate;
An exposure apparatus comprising: an illumination optical system that illuminates the original with light from a light source;
a projection optical system according to any one of claims 1 to 17, which projects the pattern of the original onto a substrate;
has
An exposure apparatus that exposes the substrate while scanning the original and the substrate. exposing a substrate using the exposure apparatus according to claim 19 or 20;
developing the exposed substrate;
producing an article from the developed substrate;
A method for manufacturing an article, comprising:

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