JP2024097677A - Projection optical system, exposure device, and method for manufacturing article - Google Patents

Abstract

To provide a projection optical system capable of achieving both higher NA and excellent optical performance.SOLUTION: A projection optical system projects light flux from an illumination area outside an optical axis on an object surface onto an image surface via a first dioptric system, a concave reflection surface, a second dioptric system, a convex reflection surface, the second dioptric system, the concave reflection surface, and a third dioptric system in this order. The concave reflection surface has an aspherical surface and is configured to satisfy predetermined conditions for light flux, which is emitted from an endpoint on a line where the illumination area and a plane bisecting the illumination area so as to include the optical axis intersect and which is incident on the concave reflection surface. When a paraxial curvature radius of the concave reflection surface is defined as positive, the predetermined conditions include a condition in which a differential value Tp at a position where a principal ray of the light flux is incident and a maximum value Tm of a differential value in a position range where a meridional upper line of the light flux is incident in a function representing a local curvature radius of the concave reflection surface with a position of the concave reflection surface in a meridional direction as a variable satisfies Tm-Tp>0.SELECTED DRAWING: Figure 1

Description

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

In the lithography process, which is a manufacturing process for semiconductor devices and flat panel displays (FPDs) such as liquid crystal or organic EL display devices, an exposure apparatus having a projection optical system can be used. In the exposure apparatus, the pattern of an original (reticle, mask) is projected via the projection optical system onto a substrate (wafer, glass plate, etc.) coated with photosensitive material (resist), thereby transferring the pattern of the original onto the substrate.

As a projection optical system for an exposure apparatus, for example, a telecentric catadioptric optical system is known in which the basic power arrangement is composed of concave and convex reflecting surfaces, and the concave and convex reflecting surfaces reflect light a total of three times. In such a projection optical system, aspheric surfaces are used for the lenses and/or mirrors that compose it, and an image of the pattern of the original illuminated in an arc-shaped effective area (illumination area) using only off-axis object points is projected onto the substrate at 1:1 magnification. Patent Document 1 proposes an advantageous projection optical system for reducing the effect of the C17 term component of the Zernike polynomial of the wavefront aberration. Patent Document 2 also proposes a projection optical system for providing an exposure apparatus that combines high performance, high throughput, and low cost.

JP 2021-56461 A Patent No. 5196869

Akiyoshi Suzuki, "Analysis of a 1:1 Two-Mirror System," Optics, Vol. 14, No. 5, October 1985

For example, exposure devices for FPDs are required to have even higher resolution, and in order to meet this demand, it is necessary to increase the NA and improve the optical performance of the projection optical system mounted on the exposure device. Patent Document 1 discloses that in a projection optical system with a high NA of 0.1 to 0.135 at unity magnification, focusing on scanning exposure, the average value of each image height of the Zernike polynomial C17 term component of the wavefront aberration is reduced. However, in the configuration described in Patent Document 1, the absolute value of the C17 term component of each image height remains large at about 100 mλ to 300 mλ, so there is a problem that the contrast of the projected image is reduced and the specified projection performance cannot be obtained. In addition, in the idea of reducing the average value of each image height of the C17 term component, there is also a problem that it is difficult to reduce the C17 term component over the entire effective area because the image height range used for scanning exposure differs between the center and the ends of the arc-shaped effective area. For example, in order to uniformly illuminate the arc-shaped effective area (arc-shaped good image area) shown in FIG. 10 of Patent Document 1 and ensure uniformity in the line width of the projected image, it is necessary to set the slit width SD equal within the effective area. In this case, the inner and outer sides that define the arc-shaped effective area have the same radius of curvature, so image heights F3 to F10 are used in the center of the effective area, but image heights F5 to F10 may be used at the edges of the effective area. Furthermore, Patent Document 2 only discloses a projection optical system with a low NA of 0.08, and does not disclose any idea of reducing the C17 term component of the Zernike polynomial of the wavefront aberration.

Therefore, the present invention aims to provide a projection optical system that can achieve both a high NA and good optical performance.

In order to achieve the above object, a projection optical system according to one aspect of the present invention is a projection optical system that projects a light beam from an illumination area located off the optical axis on an object plane onto an image plane by passing it through a first refractive optical system, a concave reflecting surface, a second refractive optical system, a convex reflecting surface, the second refractive optical system, the concave reflecting surface, and a third refractive optical system in this order, wherein the numerical aperture of the projection optical system is 0.11 or more, the concave reflecting surface, the first refractive optical system, the second refractive optical system, and the third refractive optical system each have an aspheric surface, and the concave reflecting surface is a plane that bisects the illumination area so as to include the optical axis and intersects with the illumination area. It is configured to satisfy a predetermined condition for the light beam emitted from the end point of the line and incident on the concave reflecting surface, and the predetermined condition includes a condition that, when the paraxial radius of curvature of the concave reflecting surface is defined as positive, a differential value Tp at the position where the principal ray of the light beam is incident in a function expressing the local radius of curvature of the concave reflecting surface with the position of the concave reflecting surface in the meridional direction as a variable, and a maximum value Tm of the differential value in the position range where the meridional upper line of the light beam is incident, satisfy Tm-Tp>0.

Further objects and other aspects of the present invention will become apparent from the following description of preferred embodiments thereof with reference to the accompanying drawings.

The present invention can provide, for example, a projection optical system that can achieve both a high NA and good optical performance.

FIG. 1 is a schematic diagram showing an example of the configuration of a projection optical system according to an embodiment of the present invention. Diagram showing the illumination area on the object plane A diagram showing the projection of a concave reflecting surface in the direction of the optical axis. FIG. 13 is a diagram showing the relationship between the position of a concave reflecting surface in the meridional direction and local R of the concave reflecting surface. FIG. 1 is a diagram showing the relationship between the position in the meridional direction and local R on the concave reflecting surface of the first embodiment; FIG. 1 is a diagram showing values of the tilt Tp and the maximum tilt Tm in the concave reflecting mirror of Example 1. FIG. 13 is a diagram showing a change in local aspheric surface R of the aspheric surface of the second refractive optical system of Example 1. FIG. 1 is a diagram showing various aberrations in the projection optical system of the first embodiment. FIG. 13 is a pupil map of wavefront aberration at each image height in the projection optical system of Example 1; FIG. 1 is a diagram showing a comparison result between the projection optical system of the first embodiment and a projection optical system of a conventional configuration; FIG. 13 is a diagram showing the relationship between the position in the meridional direction and local R on the concave reflecting surface of the second embodiment; FIG. 13 is a diagram showing values of the tilt Tp and the maximum tilt Tm in the concave reflecting mirror of the second embodiment. FIG. 13 is a diagram showing a change in local aspheric surface R of the aspheric surface of the second refractive optical system according to the second embodiment. FIG. 13 is a diagram showing various aberrations in the projection optical system according to the second embodiment. FIG. 13 is a diagram showing the relationship between the position in the meridional direction and local R on the concave reflecting surface of the third embodiment. FIG. 13 is a diagram showing values of the tilt Tp and the maximum tilt Tm in the concave reflecting mirror of Example 3. FIG. 13 is a diagram showing a change in local aspheric surface R of the aspheric surface of the second refractive optical system according to the third embodiment. FIG. 13 is a diagram showing various aberrations in the projection optical system according to the third embodiment. FIG. 13 is a diagram showing the relationship between the position in the meridional direction and local R on the concave reflecting surface of the fourth embodiment. FIG. 13 is a diagram showing values of the tilt Tp and the maximum tilt Tm in the concave reflecting mirror of Example 4. FIG. 13 is a diagram showing a change in local aspheric R on the aspheric surface of the second refractive optical system according to the fourth embodiment. FIG. 13 is a diagram showing various aberrations in the projection optical system according to the fourth embodiment. FIG. 13 is a diagram showing the relationship between the position in the meridional direction and local R on the concave reflecting surface of the fifth embodiment. FIG. 13 is a diagram showing values of the tilt Tp and the maximum tilt Tm in the concave reflecting mirror of Example 5. FIG. 13 is a diagram showing a change in local aspheric R on the aspheric surface of the second refractive optical system according to the fifth embodiment. FIG. 13 is a diagram showing various aberrations in the projection optical system according to the fifth embodiment. FIG. 13 is a diagram showing the relationship between the position in the meridional direction and local R on the concave reflecting surface of Example 6. FIG. 13 is a diagram showing values of the tilt Tp and the maximum tilt Tm in the concave reflecting mirror of Example 6. FIG. 23 is a diagram showing a change in local aspheric R of the aspheric surface of the second refractive optical system according to the sixth embodiment. FIG. 13 is a diagram showing various aberrations in the projection optical system according to the sixth embodiment. FIG. 1 is a diagram showing an example of the configuration of a scanning exposure apparatus; A diagram to explain the parameters of a 1:1 two-mirror system A diagram showing the C17 term component of the Zernike polynomial Schematic diagram of a conventional projection optical system FIG. 1 is a diagram showing various aberrations in a projection optical system having a conventional configuration. FIG. 13 is a diagram showing the C17 term component of the Zernike polynomial for each object height in the conventional configuration. FIG. 13 is a diagram showing a reproduction result of a change in local R of an aspheric surface in the third embodiment of Patent Document 1. FIG. 13 is a diagram showing a reproduction result of a change in local R of an aspheric surface in the third embodiment of Patent Document 1. FIG. 13 is a diagram showing a reproduction result of a change in local R of an aspheric surface in the fourth embodiment of Patent Document 1. FIG. 13 is a diagram showing a reproduction result of a change in local R of an aspheric surface in the fourth embodiment of Patent Document 1. FIG. 13 is a diagram showing the reproduction results of the change in local R of an aspheric surface in Numerical Example 1 of Patent Document 2. FIG. 13 is a diagram showing the reproduction results of the change in local R of an aspheric surface in Numerical Example 1 of Patent Document 2. FIG. 13 is a diagram showing the reproduction results of the change in local R of an aspheric surface in Numerical Example 2 of Patent Document 2. FIG. 13 is a diagram showing the reproduction results of the change in local R of an aspheric surface in Numerical Example 2 of Patent Document 2. FIG. 13 is a diagram showing the reproduction results of the change in local R of an aspheric surface in Numerical Example 3 of Patent Document 2. FIG. 13 is a diagram showing the reproduction results of the change in local R of an aspheric surface in Numerical Example 3 of Patent Document 2.

The following embodiments are described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe multiple features, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicate explanations are omitted.

First, the reason why the Zernike polynomial C17 term component of the wavefront aberration increases when increasing the NA, which is one of the objects of the present invention, will be explained using the above-mentioned non-patent document 1. According to non-patent document 1, for example, from equation (21) in non-patent document 1, the transverse aberration is proportional to the fourth power of θ and the third power of NA (φ), and in "6. Summary", it is described that "2. The remaining wavefront aberration is proportional to h/Fe ⁷ ". Since Fe = 1/(2 x NA), the remaining wavefront aberration is proportional to h x NA ^7. And, non-patent document 1 shows that the sagittal aberration in the optimized system is one order of magnitude smaller than the meridional aberration (Figure 8 (b) in non-patent document 1), and that the aberration in the ±45° direction is significant (Figure 9 (d) in non-patent document 1). The aberration in the ±45° direction corresponds to the C17 term component of the Zernike polynomial, and FIG. 19 of the present application again shows the C17 term component of the Zernike polynomial diagrammatically by a brightness distribution.

Thus, the Zernike polynomial C17 term component is an aberration occurring in the ±45° direction in the pupil plane of the projection optical system PO. This aberration distribution is called the 4θ component or the Tetrafoil component. As shown in FIG. 18 of the present application (corresponding to FIG. 1 of the non-patent document), h, φ, and θ represent parameters related to the object height, NA (numerical aperture), and chief ray angle, respectively. That is, in order to realize a high NA, it is necessary to increase φ while also increasing h and θ to ensure the distance between the convex mirror and the light rays above and below it. However, since the Zernike polynomial C17 term component of the wavefront aberration increases in proportion to NA ⁷ , it becomes difficult to increase the NA. When converted to the dominant factor NA ⁷ , for example, assuming a C17 term of 50 mλ at NA 0.1, this increases to 97 mλ, 179 mλ, 313 mλ, and 527 mλ at NA 0.11, NA 0.12, NA 0.13, and NA 0.14, respectively.

Since the diffracted light from a pattern (lines and spaces) on the object plane travels in the longitudinal direction of the pattern and in a direction perpendicular to the longitudinal direction, the diffracted light from a pattern in the ±45° direction (diagonal lines) on the object plane occurs in the ±45° direction on the pupil plane and is affected by the C17 term component. On the other hand, the diffracted light from vertical lines and horizontal patterns (vertical/horizontal lines) on the object plane is hardly affected by the C17 term component. As a result, during exposure, focus differences and line width differences are caused between the diagonal lines and the vertical/horizontal lines, reducing the line width uniformity within the screen (i.e., on the exposed substrate).

Through extensive research, the inventors have discovered a projection optical system configuration that can reduce the absolute value of the C17 term component of the Zernike polynomial of wavefront aberration, even when the NA is increased to 0.11 or higher, by setting an appropriate aspheric shape on the concave reflecting surface that is the cause of the generation of the C17 term component of the Zernike polynomial. The inventors have also discovered that the absolute value of the C17 term component can be further reduced by making the aspheric surfaces of each refractive optical system function appropriately. Below, an embodiment of the projection optical system according to the present invention is described.

[Example 1]
A first embodiment of the projection optical system according to the present invention will be described. FIG. 1 is a schematic diagram showing an example of the configuration of the projection optical system PO of the first embodiment, and shows a meridional section. The projection optical system PO has a concave reflecting surface M1 and a convex reflecting surface M2, and projects an image of an illumination area located off the optical axis on an object surface onto an image surface by reflecting the image on the concave reflecting surface M1 and the convex reflecting surface M2. In FIG. 1, OA represents the optical axis, OP represents the object surface, IP represents the image surface, L1 represents the first refractive optical system (lens), SG1 represents a refractive optical element, and DM represents a trapezoidal mirror or a plane mirror. In addition, L2 represents the second refractive optical system (meniscus lens), SG2 represents a refractive optical element, and L3 represents the third refractive optical system (lens). When the projection optical system PO is applied to an exposure apparatus, an original may be placed on the object surface OP of the projection optical system PO, and a substrate may be placed on the image surface IP of the projection optical system PO. The light beam emitted from the object plane OP with NA 0.12 passes through (or is reflected by) each optical element in the order of the optical path from the object plane OP, L1→SG1→DM→M1→L2→M2→L2→M1→DM→SG2→L3, and is imaged at the image plane IP at the same magnification. That is, the projection optical system PO of the present embodiment 1 is a unity magnification system that projects the image of the illumination area IR on the object plane OP (specifically, the image of the pattern provided in the illumination area IR) at the same magnification onto the image plane IP. In FIG. 1, since there is a flat reflecting surface DM on the way from the object plane OP to the concave reflecting surface M1, the coordinate system of the optical axis OA is described separately before and after the plane DM. In the following, all light rays (excluding the principal ray) on the meridional direction side in the +Y direction of the principal ray among the light beams emitted from one object point in the illumination area IR are defined as the upper line. The same is true for the aberration diagram. The meridional direction is defined as the direction from the optical axis OA toward the principal ray, and the meridional direction for a light beam immediately after emerging from an object point on the object plane OP is the +Y direction.

Here, in the configuration example shown in FIG. 1, the pupil position (pupil surface) of the projection optical system PO is the convex reflecting surface M2, and an aperture stop may be arranged near the convex reflecting surface M2. In addition, the concave reflecting surface M1, the first refractive optical system L1, the second refractive optical system L2, and the third refractive optical system L3 have aspheric surfaces. The refractive optical elements SG1 and SG2 can be used to adjust the imaging magnification or distortion aberration.

Figure 2A shows the illumination area IR of the object plane OP when the object plane OP is viewed from above in Figure 1. The illumination area IR may be understood as an area where an original placed on the object plane OP is illuminated by slit light, and may be called an effective area. The illumination area IR is located outside the optical axis (outside the optical axis OA) on the object plane OP so as not to include the optical axis OA. In this embodiment 1, the illumination area IR is arc-shaped, but is not limited to this and may be rectangular. Also, in this embodiment 1, as shown in Figure 2A, the length in the Y-axis direction, which is the short side direction of the illumination area IR, is represented as the slit width Sw, the length in the X-axis direction, which is the long side direction, is represented as the illumination width W, the upper limit in the meridional plane of the illumination area IR is represented as the maximum object height Ya, and the lower limit is represented as the minimum object height Yi.

Here, the object height (maximum object height Ya, minimum object height Yi) is defined as the height (distance) from the optical axis OA on the object plane, and is sometimes called the object height. The meridional plane can be defined as a plane (meridional plane) that includes the optical axis OP and the chief ray that passes through the center of gravity of the illumination area IR as an object point, that is, as a plane that bisects the illumination area IR so as to include the optical axis OP. In other words, the maximum object height Ya is the one of the two end points of the line where the illumination area IR and the meridional plane intersect, which is farther from the optical axis OA, and the minimum object height Yi is the other of the two end points that is closer to the optical axis OA.

Figure 2B shows the optical axis direction projection of concave reflecting surface M1 as viewed from convex reflecting surface M2 in Figure 1. Figure 2B shows the incidence ranges of the light beams emitted with minimum object height Yi and maximum object height Ya as object points. The range shown by the dotted line is the incidence range of light beam LBa (first light beam) emitted from maximum object height Ya, and the range shown by the two-dot chain line is the incidence range of light beam LBi (second light beam) emitted from minimum object height Yi.

In FIG. 2B, for the light beam LBa emitted from the maximum object height Ya, the incident position of the principal ray rp is indicated by an x mark, the incident position of the sagittal marginal ray rs (peripheral ray) is indicated by an ▲ mark, and the incident position of the azimuth 45° direction marginal ray r45 (peripheral ray) is indicated by a ■ mark. The distances from the optical axis OA to the incident positions of the rays rp, rs, and r45 are Rp, Rs, and R45, respectively. The distance from the optical axis OA to the incident position of the meridional marginal ray (peripheral ray) is Rm. Note that the incident positions of the principal ray, sagittal marginal ray, and azimuth 45° direction marginal ray of the light beam LBi emitted from the minimum object height Yi are similar to those of the light beam LBa emitted from the maximum object height Ya, but are not shown in FIG. 2B.

In addition, in FIG. 2B, circles with radii Rs, R45, and Rm centered on the optical axis OA are shown by dotted line a, dashed line b, and solid line c, respectively. The differences from the incident position of the principal ray rp to the incident positions of each ray as the length over which the aspheric surface acts are (Rm-Rp), (R45-Rp), and (Rs-Rp) in descending order. Furthermore, since the aspheric surface of the concave reflecting surface M1 has a concentric shape symmetrical with respect to the optical axis, the change direction of the aspheric surface coincides with the meridional direction. Therefore, since the aberration correction effect of the aspheric surface is greatest in the meridional direction, it is possible to reduce the difference with the aberration in the azimuth 45° direction by controlling the aberration of the upper line in the meridional direction. As mentioned above, the meridional direction is defined as the direction from the optical axis OA toward the principal ray (specifically, the incident position of the principal ray). The upper line in the meridional direction is defined as including all light rays (upper rays) that are on the positive side of the meridional direction (Y direction) from the principal ray among the light beams that are emitted from one object point (maximum object height Ya, minimum object height Yi) in the illumination area IR and enter the concave reflecting surface M1. Hereinafter, the upper line in the meridional direction may be referred to as the "upper meridional line."

In the projection optical system PO of the first embodiment, the aspheric concave reflecting surface M1 is configured to satisfy a predetermined condition for a light beam emitted from an end point of a line where the illumination region IR and the meridional plane intersect and incident on the concave reflecting surface M1. The predetermined condition includes a condition that the following formula (1) is satisfied. This makes it possible to satisfactorily correct the C17 term component of the Zernike polynomial at all image heights while increasing the NA in the projection optical system PO.
Tm-Tp>0...(1)

The above formula (1) is based on the premise that the paraxial radius of curvature of the concave reflecting surface M1 is defined as positive (specifically, positive data setting). In formula (1), in a function that expresses the local radius of curvature of the concave reflecting surface M1 with the position of the concave reflecting surface M1 in the meridional direction as a variable, the differential value at the position where the principal ray of the light beam is incident is Tp, and the maximum value of the differential value in the position range where the meridional upper line of the light beam is incident is Tm. The light beam can be each of the light beam LBa (first light beam) emitted from the maximum object height Ya and the light beam LBi (second light beam) emitted from the minimum object height Yi. In other words, in this embodiment 1, the concave reflecting surface M1 is configured so that the above formula (1) is satisfied for both the light beam LBa and the light beam LBi. In the following, the local radius of curvature (local radius of curvature) of the concave reflecting surface M1 may be referred to as "local R", the differential value Tp at the position where the principal ray is incident may be referred to as "slope Tp", and the maximum value Tm of the differential value in the range of positions where the meridional upper line is incident may be referred to as "maximum slope Tm".

Here, the condition of the above formula (1) will be explained with reference to FIG. 2C. FIG. 2C shows an example of a function that expresses the relationship between the position of the concave reflecting surface M1 in the meridional direction and the local R of the concave reflecting surface M1, that is, the local R of the concave reflecting surface M1 with the position of the concave reflecting surface M1 in the meridional direction as a variable. The concave reflecting surface M1 of this embodiment 1 is configured to satisfy the condition of the above formula (1) for both the light beam LBa from the maximum object height Ya and the light beam LBi from the minimum object height Yi. Specifically, the concave reflecting surface M1 is configured such that, for the light beam LBa from the maximum object height Ya, the differential value Tpa of the function at the position where the principal ray is incident and the maximum value Tma of the differential value of the function in the position range where the meridional upper line is incident satisfy (Tma-Tpa>0). Furthermore, the concave reflecting surface M1 is configured so that for the light beam LBi from the minimum object height Yi, the differential value Tpi of the function at the position where the principal ray is incident and the maximum value Tmi of the differential value of the function in the range of positions where the meridional upper line is incident satisfy (Tmi-Tpi>0).

3A shows the relationship between the position of the concave reflecting surface M1 in the meridional direction and the local R of the concave reflecting surface M1 when the minimum object height Yi = 470 and the maximum object height Ya = 520 in this embodiment 1. In FIG. 3A, the horizontal axis shows the position h of the concave reflecting surface M1 in the meridional direction (i.e., the height in the radial direction), and the vertical axis shows the local R of the concave reflecting surface M1 (i.e., the local radius of curvature). FIG. 3A shows the position ranges where the chief ray and the meridional upper line of the light beam emitted from each of the minimum object height Yi and the minimum object height Ya are incident. The left end of the position range is the incident position of the chief ray, and the maximum value of the inclination within the position range shows a value larger in the positive direction than the inclination at the incident position of the chief ray. FIG. 3B shows the numerical values for the inclination Tp and the maximum inclination Tm in the example of FIG. 3A, and the example of FIG. 3A satisfies the condition of the above formula (1).

The aberration of the conventional projection optical system will be described later, but the halo component, especially in the 45° azimuth direction, remains over, which is the reason for the increase in the absolute value of the C17 component of the Zernike polynomial. According to the above formula (1), the aberration of the meridional upper line is controlled to be over, so the difference in aberration in the 45° azimuth direction can be reduced, and the absolute value of the C17 component of the Zernike polynomial can be reduced.

In addition, since the projection optical system PO of this embodiment 1 is an equal-magnification symmetric optical system, the light beam emitted from the object point (maximum object height Ya, minimum object height Yi) in the illumination area IR is reflected twice by the concave reflecting surface M1. The above describes the first reflection at the upper part of the concave reflecting surface M1, but the second reflection at the lower part of the concave reflecting surface M1 is subjected to the same aspheric action as the first reflection. This reduces the difference in wavefront aberration in the meridional direction and the azimuth 45° direction, so that the absolute value of the C17 term component of the Zernike polynomial can be further reduced. The aspheric surfaces of the first and third refractive optical systems L1 and L3, which are symmetrically arranged, mainly correct the field curvature, and the aspheric surface of the second refractive optical system L2, which is close to the pupil, corrects the balance of lateral aberration at all image heights so as to compensate for the action of the aspheric surface of the concave reflecting surface M1. Specifically, the second refractive optical system L2 has an area for compensating (reducing) the change in the differential value (slope) of the above function in the range from the position where the principal ray of the light beam (LBa, LBi) is incident on the concave reflecting surface M1 to the position where the meridional marginal ray of the light beam is incident. The range from the position where the principal ray is incident to the position where the meridional marginal ray is incident may be understood as the range of the incidence position of the meridional upper ray plus the incidence position of the principal ray in FIG. 2C. In addition, the projection optical system PO of this embodiment 1, which is an equal-magnification symmetric system with the convex reflecting surface M2 as the pupil, is configured so that coma aberration and distortion aberration do not occur.

Next, to clarify the effect (correction mechanism) of the configuration of the projection optical system PO of this embodiment 1 on the projection optical system POc of the conventional configuration, the results of an attempt to design a projection optical system POc of the conventional configuration will be described. The projection optical system POc of the conventional configuration has the same optical specifications as the projection optical system PO of this embodiment 1 shown in FIG. 1, except that the concave reflecting surface M1 is a spherical surface.

As shown in Table 1 below, the optical specifications of the conventional projection optical system POc are i-line dominant wavelength, NA 0.12, illumination width W = 800 mm, and slit width Sw = 50 mm (object height 470-520 mm). Tables 2 and 3 below show examples of the values of various parameters used in the design of the conventional projection optical system POc. FIG. 20 shows a schematic diagram of the conventional projection optical system POc, and FIG. 21 shows an aberration diagram of the conventional projection optical system POc. FIG. 21 also shows the wavefront aberration RMS of the i-line and the numerical value of the C17 term component of the Zernike polynomial. FIG. 22 is a pupil map of the wavefront aberration at each image height (each object height) at the i-line wavelength, and the scale on the right side of the figure is -400 to +400 mλ.

Note that in aberration diagrams, the indication of the meridional upper line, meridional lower line, and sagittal ray is usually switched depending on the sign of the entrance pupil position based on the object plane. However, in all aberration diagrams, the meridional upper line and meridional lower line defined on the light path diagram are corrected so that they correspond to the aberration diagram. The meridional lower line is defined as including all rays (lower rays) on the negative side of the meridional direction from the principal ray among the light beams emitted from one object point in the illumination region IR. In addition, in the numerical example shown in Table 2, a dummy reflecting surface is inserted just before the image plane so that the image field has a positive interval and a positive refractive index, making the total number of reflecting surfaces an even number. The above settings are used in common in all embodiments described in this specification.

In the conventional projection optical system POc, the dominant wavelength is 365.5 nm (i-line). FIG. 21 shows, from the left, the transverse aberrations of meridional, sagittal, and 45° azimuth, the wavefront aberration RMS of the i-line wavelength, and the Zernike polynomial C17 term component for the conventional projection optical system POc. The behavior (halo component) of the light beam ratio of 50% to 100% is different between meridional and sagittal versus 45° azimuth. The former meridional and sagittal tend to be under-corrected overall, while the latter 45° azimuth is over-corrected. As a result, the Zernike polynomial C17 term remains large at 162.7 to 207.7 mλ, and the wavefront aberration RMS is also large at 62.1 to 74.0 mλ, resulting in a decrease in the contrast of the projected image. It can be seen from Fig. 22 that the C17 term component of the Zernike polynomial as shown in Fig. 19 remains large. As described above using Non-Patent Document 1, it can be seen that it is at the same level as the numerical value converted at NA ⁷ .

In contrast, in this embodiment 1, the concave reflecting surface M1 (aspheric surface) is configured so that the above formula (1) is satisfied. FIG. 4 shows, from the left, the meridional, sagittal, and azimuth 45° transverse aberrations, the wavefront aberration RMS of the i-line wavelength, and the Zernike polynomial C17 term component for the projection optical system PO of this embodiment 1. As shown in FIG. 4, in the configuration of the projection optical system PO (concave reflecting surface M1) of this embodiment 1, the Zernike polynomial C17 term component is very small at -8.7 to 6.3 mλ, and the wavefront aberration RMS is also small at 6.1 to 14.0 mλ, and these aberrations are well corrected. FIG. 5 is a pupil map of the wavefront aberration at each image height (each object height) at the i-line wavelength, and the scale on the right side of the figure is -400 to +400 mλ. As shown in Fig. 5, the wavefront is corrected better in the projection optical system PO of this embodiment 1 than in the projection optical system POc of the conventional configuration (Fig. 22). Fig. 6 shows the results of comparing the Zernike polynomial C17 term component for each image height in the projection optical system PO of this embodiment 1 and the projection optical system POc of the conventional configuration. The difference between the projection optical system PO of this embodiment 1 and the projection optical system POc of the conventional configuration is whether or not the concave reflecting surface M1 is an aspheric surface that satisfies the condition of the above formula (1), but it can be seen that the absolute value of the Zernike polynomial C17 term component is corrected very well in this embodiment 1.

Here, Patent Documents 1 and 2 describe examples in which an aspheric surface is used on the concave reflecting surface of a projection optical system. In Patent Document 1, the examples in which an aspheric surface is used on the concave reflecting surface are the third and fourth embodiments, and in Patent Document 2, the examples in which an aspheric surface is used on the concave reflecting surface are Numerical Examples 1 to 3. However, Patent Documents 1 and 2 do not describe the idea of defining the aspheric shape of the concave reflecting surface in order to reduce the absolute value of the C17 term component of the Zernike polynomial as in this Example 1. Below, for verification, the results of reproducing the configurations of Patent Documents 1 and 2 are shown.

First, the results of reproducing the change in aspherical local R in the third and fourth embodiments of Patent Document 1 are shown in Figures 23A to 23B and Figures 24A to 24B, respectively. The difference in aspherical local R in Figures 23A and 24A from the axis to the periphery increases monotonically to about 38 mm and 25 mm, respectively. This is an order of magnitude larger than the change in aspherical local R in this Example 1 (within 3 mm). Therefore, with the configuration of Patent Document 1, referring to Figures 23B and 24B, it is presumed that the meridional aberration is excessively controlled over, exceeding the range in which the C17 term component of the Zernike polynomial is uniformly corrected for image height, and instead the image height difference increases.

In addition, the configuration of Patent Document 1 differs from the configuration of this Example 1 in that the second refractive optical system does not have an aspheric surface, and therefore it is difficult to appropriately compensate (reduce) the aspheric action of the concave reflecting surface. In the configuration of Patent Document 1, the convex reflecting surface near the second refractive optical system is aspheric, but since the convex reflecting surface is the pupil surface, it is only possible to control aberrations collectively at all image heights. Furthermore, due to the principle of Petzval sum correction of an equal-magnification two-mirror system, the degree of freedom to change the radius of curvature of the convex reflecting surface is also limited. As a result, as shown in Figures 19 and 18 of Patent Document 1, the average value of the Zernike polynomial C17 term component obtained by scanning exposure is small, but the absolute value of the Zernike polynomial C17 term component at each image height cannot be reduced. On the other hand, in the present invention, as in this Example 1, an aspheric surface is used for the second refractive optical system L2 away from the pupil surface. This distributes the positions at which light rays pass from each object height (each object point), which results in a greater effect of compensating for the aspheric action of the concave reflecting surface M1, where the positions at which light rays pass from each object height are distributed. In addition, because bending is possible on both sides of the lens as the second refractive optical system L2, the degree of freedom in setting an appropriate radius of curvature for aberration correction can also be improved.

Next, the results of reproducing the change in local R of the aspheric surface in numerical examples 1 to 3 of Patent Document 2 are shown in Figures 25A to 25B, 26A to 26B, and 27A to 27B, respectively. With reference to Figures 25B, 26B, and 27B, the numerical examples of Patent Document 2 do not satisfy the above formula (1). That is, for either or both of the light rays from the minimum object height and the maximum object height, there is no position within the range of incidence positions of the meridional upper line where the maximum slope Tm is greater than the slope Tp at the incidence position of the principal ray. Therefore, it is difficult to reduce the absolute value of the C17 term component of the Zernike polynomial when increasing the NA.

Below, we will explain more preferable configuration conditions for increasing the NA and reducing the absolute value of the CN17 term component of the Zernike polynomial in the projection optical system PO of this embodiment 1.

In the projection optical system PO of this embodiment 1, it is more preferable that the concave reflecting surface M1 is configured to satisfy the following formula (2) as a predetermined condition. In principle, by satisfying the above formula (1), the absolute value of the C17 term component of the Zernike polynomial is reduced, but in order to obtain a greater correction effect, the lower limit value of (Tm-Ta) should be set to a value greater than "0.0004". The lower limit value is set based on the minimum value obtained from the results of designing a plurality of embodiments by changing the positions of the first refractive optical system L1 and the third refractive optical system L3, and the aspheric shape (aspheric amount) of the concave reflecting surface M1 as parameters with an NA of 0.11 or more. Note that the upper limit value is not particularly set because it changes depending on the optical specifications, such as when the NA is increased beyond this embodiment 1, the constraints of the aspheric shape (aspheric amount) in processing/measurement, and changes in the slit width, but "0.028" is given as an example.
Tm-Tp>0.0004...(2)

In the projection optical system PO of the first embodiment, it is more preferable that the concave reflecting surface M1 is configured to satisfy the following formula (3) as a predetermined condition. In the following formula (3), "Tpa" is the inclination Tp at the position where the principal ray of the light beam LBa from the maximum object height Ya is incident, and "Tpi" is the inclination Tp at the position where the principal ray of the light beam LBi from the minimum object height Yi is incident. This condition is a condition for uniformly and efficiently correcting (reducing) the Zernike polynomial C17 term component (see FIG. 6) that occurs uniformly at all image heights as in the conventional configuration, and is particularly effective for the change in local R of the concave reflecting surface M1 in the meridional direction. If this condition is not satisfied, the change in local R of the concave reflecting surface M1 increases, and the image height difference of the Zernike polynomial C17 term component may occur in the aspheric surface of the concave reflecting surface M1 itself. As shown in FIG. 23B and FIG. 24B, the third and fourth embodiments of Patent Document 1 largely deviate from the condition of formula (3).
|Tpa-Tpi|<0.001...(3)

In addition, in the projection optical system PO of the first embodiment, the concave reflecting surface M1 having an aspheric surface may be configured to satisfy the following formula (4) with respect to the approximate spherical surface determined by the optical axis OA and the effective diameter. This is a condition for making the aspheric shape (aspheric amount) measurable by spherical interferometer measurement. If the aspheric sag amount (aspheric sag amount) of the concave reflecting surface M1 is 10 μm or more, it is necessary to prepare a null element dedicated to the test surface or to prepare a master prototype having a shape equivalent to the test surface for system error calibration of the interferometer. In this case, the cost of capital investment will be large. Therefore, it is preferable to make the aspheric sag amount of the concave reflecting surface M1 smaller than 10 μm, as in the condition of the following formula (4).
Aspheric surface sag amount < 10 μm ... (4)

Next, the specific specifications of the projection optical system PO of the first embodiment will be described. The configuration of the projection optical system PO of the first embodiment has been described above with reference to FIG. 1. Table 4 below shows the optical specifications 1 of the projection optical system PO of the first embodiment, and also includes the specifications shown in FIG. 2A. The projection optical system PO of the first embodiment has a dominant wavelength of the i-line, a high NA of 0.12, an exposure width of 800 mm, and a slit width of 50 mm. Tables 5 to 6 below show examples of numerical values of various parameters in the projection optical system PO of the first embodiment. In Table 5, "surface number" indicates the number given to the multiple surfaces provided in the projection optical system PO in the order of the optical path from the object surface OP. "Aspheric setting" indicates whether each surface is aspheric or not, and the surface marked with "ASP" is aspheric. "R" indicates the radius of curvature (mm), "D" indicates the surface distance (mm), and "glass" indicates the glass material. However, the refractive index of air is 1, surfaces with "glass" set to "-1" indicate surfaces that have been reflected an odd number of times, and surfaces with "SiO2" indicate that the glass material is synthetic quartz. Table 5 also shows the refractive index for each wavelength. Furthermore, "asp_data" shown in Table 6 is an aspheric coefficient, and all aspheric surfaces in the projection optical system PO of the embodiment according to the present invention can be defined by the aspheric equation expressed by the following equation (5). The projection optical system PO of the embodiment 1 configured in this way satisfies all of the conditions of the above equations (1) to (4), as shown in FIG. 3B.
z=(1/R)h ² /(1+(1-(1+k)(1/R) ² h ² ) ^1/2 )
+Ah ⁴ +Bh ⁶ +Ch ⁸ +Dh ¹⁰ +Eh ¹² +Fh ¹⁴ +Gh ¹⁶ +Hh ¹⁸ +Jh ²⁰
...(5)
Here, when f(h)=z in the above formula (5), the local R of the aspheric surface can be calculated by the following formula (6). In the following formula (6), "f"" represents the second derivative of f(h), and "f'" represents the first derivative of f(h).

Figure 3C shows the change in aspheric local R on the aspheric surface (surface number 8) of the second refractive optical system L2 when the minimum object height Yi = 470 and the maximum object height Ya = 520. In Figure 3C, the horizontal axis shows the position h in the meridional direction (i.e., the height in the radial direction), and the vertical axis shows the local R (i.e., the local radius of curvature) of the concave reflecting surface M1. Figure 3C shows the position ranges in which the chief ray and the meridional upper line of the light beam emitted from each of the minimum object height Yi and the maximum object height Ya are incident. The left end of the position range is the incident position of the chief ray. The second refractive optical system L2 of this embodiment 1 has a region in which the inclination within the position range is in the negative direction from the incident position of the chief ray so as to compensate for the change in the inclination of the aspheric local R of the concave reflecting surface M1 that satisfies the formula (1) (see Figure 3A). This allows for a balanced correction of lateral aberrations at all image heights, and mainly corrects the field curvature at the aspheric surface (surface number 2) of the first refractive optical system L1 and the aspheric surface (surface number 18) of the third refractive optical system L3, resulting in good overall optical performance of the projection optical system PO. This is as described above with reference to FIG. 4.

[Example 2]
A projection optical system according to a second embodiment of the present invention will now be described. The second embodiment basically inherits the contents described in the first embodiment, and is the same as that described in the first embodiment except for what will be mentioned below. For example, the conditions and various definitions shown in equations (1) to (4) are the same as those described in the first embodiment. The projection optical system according to the second embodiment has a similar configuration to the projection optical system PO of the first embodiment described above with reference to FIG. 1.

The following Table 7 shows the optical specification 2 of the projection optical system of the present embodiment 2, and also includes the specifications shown in FIG. 2A. The projection optical system of the present embodiment 2 has a dominant wavelength of the i-line, a high NA of 0.11, an exposure width of 800 mm, and a slit width of 50 mm. The following Tables 8 and 9 show examples of the numerical values of various parameters in the projection optical system of the present embodiment 2. The explanation of the table and the aspheric formula are the same as those in the first embodiment. In the projection optical system of the present embodiment 2 configured in this way, the relationship between the position of the concave reflecting surface M1 in the meridional direction and the local R of the concave reflecting surface M1 is shown in FIG. 7A. Also, FIG. 7B shows the numerical values for the tilt Tp and the maximum tilt Tm in the example of FIG. 7A. As shown in FIG. 7B, the projection optical system of the present embodiment 2 satisfies all the conditions of the above formulas (1) to (4). In the second embodiment, the formula (1) is satisfied, but the aspheric local R is reduced. In this case, the effect of the concave reflecting surface M1 on the meridional upper line is under-corrected, but the field curvature can be corrected by the aspheric surfaces of the first and third refractive optical systems L1 and L3, and the lateral aberration can be corrected by the aspheric surface of the second refractive optical system L2. Since it is important to control the halo component of the meridional upper line in order to correct the C17 term component of the Zernike polynomial, satisfying formula (1) with the concave reflecting surface M1 is effective.

Figure 7C shows the change in aspheric local R in the aspheric surface (surface number 8) of the second refractive optical system L2 when the minimum object height Yi = 450 and the maximum object height Ya = 500. The explanation of the figure is the same as in Example 1. The second refractive optical system L2 of this Example 2 has a region in which the inclination within the range of positions where the meridional upper line is incident is in the negative direction from the position of incidence of the principal ray so as to compensate for the change in the inclination of the aspheric local R of the concave reflecting surface M1 that satisfies the formula (1) (see Figure 7A). As a result, as shown in Figure 8, along with the balance correction of the lateral aberration of the entire image height, mainly the curvature of field is corrected in the aspheric surface (surface number 2) of the first refractive optical system L1 and the aspheric surface (surface number 18) of the third refractive optical system L3, and good optical performance is obtained as a whole of the projection optical system. FIG. 8 shows, from the left, the meridional, sagittal, and 45° azimuth lateral aberrations, the wavefront aberration RMS of the i-line wavelength, and the C17 term component of the Zernike polynomial for the projection optical system of this embodiment. As shown in FIG. 8, in the configuration of the projection optical system of this embodiment, the lateral aberrations are well corrected in the meridional, sagittal, and 45° azimuth directions. In addition, the wavefront aberration RMS of the i-line, which is the dominant wavelength, is small at 2.0 to 3.3 mλ, and the absolute value of the C17 term component of the Zernike polynomial is also small at -1.8 to 1.9 mλ, and these aberrations are also well corrected.

[Example 3]
A projection optical system according to a third embodiment of the present invention will be described. The third embodiment basically inherits the contents described in the first embodiment, and is the same as that described in the first embodiment except for what will be mentioned below. For example, the conditions and various definitions shown in the expressions (1) to (4) are the same as those described in the first embodiment. The projection optical system according to the third embodiment has a basically similar configuration to the projection optical system PO according to the first embodiment described above with reference to FIG. 1, but differs in that the R2 surface of the meniscus lens constituting the second refractive optical system L2 is an aspheric surface.

The following Table 10 shows the optical specification 3 of the projection optical system of this embodiment 3, and also includes the specifications shown in FIG. 2A. The projection optical system of this embodiment 3 has a dominant wavelength of the i-line, a high NA of 0.13, an exposure width of 800 mm, and a slit width of 50 mm. The following Tables 11 and 12 show examples of the values of various parameters in the projection optical system of this embodiment 3. The explanation of the table and the aspheric formula are the same as those in the first embodiment. In the projection optical system of this embodiment 3 configured in this way, the relationship between the position of the concave reflecting surface M1 in the meridional direction and the local R of the concave reflecting surface M1 is shown in FIG. 9A. Also, FIG. 9B shows the values of the tilt Tp and the maximum tilt Tm in the example of FIG. 9A. As shown in FIG. 9B, the projection optical system of this embodiment 3 satisfies all of the conditions of the above formulas (1) to (4).

Figure 9C shows the change in the aspheric local R in the aspheric surface (surface number 9) of the second refractive optical system L2 when the minimum object height Yi = 470 and the maximum object height Ya = 520. The explanation of the figure is the same as in Example 1. The second refractive optical system L2 of this Example 3 has a region in which the inclination within the range of the position where the meridional upper line is incident is in the positive direction from the position of incidence of the principal ray. In this Example 3, unlike Examples 1 and 2, since surface number 9 indicates the concave surface of the R2 surface of the lens, the change in the inclination of the aspheric local R of the concave reflecting surface M1 that satisfies formula (1) (see Figure 9A) can be compensated by changing the inclination in the positive direction. As a result, as shown in Figure 10, along with the balance correction of the lateral aberration at all image heights, mainly the field curvature is corrected in the aspheric surface (surface number 2) of the first refractive optical system L1 and the aspheric surface (surface number 18) of the third refractive optical system L3, and good optical performance is obtained as a whole of the projection optical system. Figure 10 shows, from left to right, the meridional, sagittal, and 45° azimuth lateral aberrations, the wavefront aberration RMS of the i-line wavelength, and the C17 term component of the Zernike polynomial for the projection optical system of this embodiment 3. As shown in Figure 10, in the configuration of the projection optical system of this embodiment 3, the lateral aberrations are well corrected in the meridional, sagittal, and 45° azimuth directions. In addition, the wavefront aberration RMS of the i-line, which is the dominant wavelength, is small at 9.6 to 20.3 mλ, and the absolute value of the C17 term component of the Zernike polynomial is also small at -19.9 to 9.9 mλ, and these aberrations are also well corrected.

[Example 4]
A fourth embodiment of the projection optical system according to the present invention will now be described. The fourth embodiment basically inherits the contents described in the first embodiment, and is the same as that described in the first embodiment except for what will be mentioned below. For example, the configuration conditions and various definitions shown in expressions (1) to (4) are the same as those described in the first embodiment. The projection optical system of the fourth embodiment has a similar configuration to the projection optical system PO of the first embodiment described above with reference to FIG. 1.

The following Table 13 shows the optical specification 4 of the projection optical system of this embodiment 4, and also includes the specifications shown in FIG. 2A. The projection optical system of this embodiment 4 has a dominant wavelength of the i-line, a high NA of 0.14, an exposure width of 800 mm, and a slit width of 40 mm. The following Tables 14 and 15 show examples of the numerical values of various parameters in the projection optical system of this embodiment 4. The explanation of the table and the aspheric formula are the same as those in the first embodiment. In the projection optical system of this embodiment 4 configured in this way, the relationship between the position of the concave reflecting surface M1 in the meridional direction and the local R of the concave reflecting surface M1 is shown in FIG. 11A. Also, FIG. 11B shows numerical values related to the tilt Tp and the maximum tilt Tm in the example of FIG. 11A. As shown in FIG. 11B, the projection optical system of this embodiment 4 satisfies all of the conditions of the above formulas (1) to (4).

Figure 11C shows the change in the aspheric local R in the aspheric surface (surface number 8) of the second refractive optical system L2 when the minimum object height Yi = 474 and the maximum object height Ya = 514. The explanation of the figure is the same as in Example 1. The second refractive optical system L2 of this Example 4 has a region in which the inclination within the range of the position where the meridional upper line is incident is in the negative direction from the incident position of the chief ray so as to compensate for the change in the inclination of the aspheric local R of the concave reflecting surface M1 that satisfies the formula (1) (see Figure 11A). As a result, as shown in Figure 12, along with the balance correction of the lateral aberration of the entire image height, mainly the curvature of field is corrected in the aspheric surface (surface number 2) of the first refractive optical system L1 and the aspheric surface (surface number 18) of the third refractive optical system L3, and good optical performance is obtained as a whole of the projection optical system. Figure 12 shows, from left to right, the meridional, sagittal, and 45° azimuth lateral aberrations, the wavefront aberration RMS of the i-line wavelength, and the C17 term component of the Zernike polynomial for the projection optical system of this embodiment 4. As shown in Figure 12, in the configuration of the projection optical system of this embodiment 4, the lateral aberrations are well corrected in the meridional, sagittal, and 45° azimuth directions. In addition, the wavefront aberration RMS of the i-line, which is the dominant wavelength, is small at 9.7 to 19.8 mλ, and the absolute value of the C17 term component of the Zernike polynomial is also small at -10.7 to 7.4 mλ, and these aberrations are also well corrected.

[Example 5]
A projection optical system according to a fifth embodiment of the present invention will now be described. The fifth embodiment basically inherits the contents described in the first embodiment, and is the same as that described in the first embodiment except for what will be mentioned below. For example, the configuration conditions and various definitions shown in expressions (1) to (4) are the same as those described in the first embodiment. The projection optical system according to the fifth embodiment has a similar configuration to the projection optical system PO of the first embodiment described above with reference to FIG. 1.

The following Table 16 shows the optical specification 5 of the projection optical system of this embodiment 5, and also includes the specifications shown in FIG. 2A. The projection optical system of this embodiment 5 has a dominant wavelength of i-line, a high NA of 0.14, an exposure width of 800 mm, and a slit width of 40 mm. The following Tables 17 to 18 show examples of the numerical values of various parameters in the projection optical system of this embodiment 5. The explanation of the table and the aspheric formula are the same as those in the embodiment 1. In the projection optical system of this embodiment 5 configured in this way, the relationship between the position of the concave reflecting surface M1 in the meridional direction and the local R of the concave reflecting surface M1 is shown in FIG. 13A. Also, FIG. 13B shows numerical values related to the tilt Tp and the maximum tilt Tm in the example of FIG. 13A. As shown in FIG. 13B, the projection optical system of this embodiment 5 satisfies all of the conditions of the above formulas (1) to (4). Example 5 has the same optical specifications as Example 4, but the distance from the object surface OP (surface number 1) to the first refractive optical system L1 (as well as the distance from the third refractive optical system L3 to the image surface IP (surface number 22) because it is an equal-magnification symmetric system) is different from Example 4. Also, in Example 5, the amount of aspheric sag defined by formula (4) is larger than in Example 4.

Figure 13C shows the change in aspheric local R in the aspheric surface (surface number 8) of the second refractive optical system L2 when the minimum object height Yi = 474 and the maximum object height Ya = 514. The explanation of the figure is the same as in Example 1. The second refractive optical system L2 of this Example 5 has a region in which the inclination within the range of the position where the meridional upper line is incident is in the negative direction from the incident position of the chief ray so as to compensate for the change in the inclination of the aspheric local R of the concave reflecting surface M1 that satisfies the formula (1) (see Figure 13A). As a result, as shown in Figure 14, along with the balance correction of the lateral aberration of the entire image height, mainly the curvature of field is corrected in the aspheric surface (surface number 2) of the first refractive optical system L1 and the aspheric surface (surface number 18) of the third refractive optical system L3, and good optical performance is obtained as a whole of the projection optical system. Figure 14 shows, from the left, the meridional, sagittal, and 45° azimuth lateral aberrations, the wavefront aberration RMS of the i-line wavelength, and the C17 term component of the Zernike polynomial for the projection optical system of this embodiment 5. As shown in Figure 14, in the configuration of the projection optical system of this embodiment 5, the lateral aberrations are well corrected in the meridional, sagittal, and 45° azimuth directions. In addition, the wavefront aberration RMS of the i-line, which is the dominant wavelength, is small at 10.2 to 20.5 mλ, and the absolute value of the C17 term component of the Zernike polynomial is also small at -5.9 to 6.4 mλ, and these aberrations are also well corrected.

[Example 6]
A sixth embodiment of the projection optical system according to the present invention will now be described. The sixth embodiment basically inherits the contents described in the first embodiment, and is the same as that described in the first embodiment except for what will be mentioned below. For example, the configuration conditions and various definitions shown in expressions (1) to (4) are the same as those described in the first embodiment. The projection optical system of the sixth embodiment has a similar configuration to the projection optical system PO of the first embodiment described above with reference to FIG.

The following Table 19 shows the optical specifications 6 of the projection optical system of this embodiment 6, and also includes the specifications shown in FIG. 2A. The projection optical system of this embodiment 6 has a dominant wavelength of i-line, a high NA of 0.14, an exposure width of 800 mm, and a slit width of 50 mm. The following Tables 20 to 21 show examples of the values of various parameters in the projection optical system of this embodiment 6. The explanation of the table and the aspheric formula are the same as those in the first embodiment. In the projection optical system of this embodiment 6 configured in this way, the relationship between the position of the concave reflecting surface M1 in the meridional direction and the local R of the concave reflecting surface M1 is shown in FIG. 15A. Also, FIG. 15B shows the values of the tilt Tp and the maximum tilt Tm in the example of FIG. 15A. As shown in FIG. 15B, the projection optical system of this embodiment 6 satisfies all of the conditions of the above formulas (1) to (4). In Example 6, the NA is the same as in Examples 4 to 5, but the slit width is larger, and the amount of aspheric sag defined by formula (4) is larger than in Examples 4 to 5. In Example 6, formula (1) is satisfied, but the aspheric local R is significantly reduced. In this case, the effect of the concave reflecting surface M1 on the meridional upper line is under-corrected, but the field curvature can be corrected by the aspheric surfaces of the first and third refractive optical systems L1 and L3, and the lateral aberration can be corrected by the aspheric surface of the second refractive optical system L2. In order to correct the C17 term component of the Zernike polynomial, it is important to control the halo component of the meridional upper line, so by satisfying formula (1) with the concave reflecting surface M1, the effect is achieved.

Figure 15C shows the change in the aspheric local R in the aspheric surface (surface number 8) of the second refractive optical system L2 when the minimum object height Yi = 470 and the maximum object height Ya = 520. The explanation of the figure is the same as in Example 1. The second refractive optical system L2 of this Example 6 has a region in which the inclination within the range of the position where the meridional upper line is incident is in the negative direction from the incident position of the chief ray so as to compensate for the change in the inclination of the aspheric local R of the concave reflecting surface M1 that satisfies the formula (1) (see Figure 15A). As a result, as shown in Figure 16, along with the balance correction of the lateral aberration of the entire image height, mainly the curvature of field is corrected in the aspheric surface (surface number 2) of the first refractive optical system L1 and the aspheric surface (surface number 18) of the third refractive optical system L3, and good optical performance is obtained as a whole of the projection optical system. Figure 16 shows, from left to right, the meridional, sagittal, and 45° azimuth lateral aberrations, the wavefront aberration RMS of the i-line wavelength, and the C17 term component of the Zernike polynomial for the projection optical system of this embodiment 6. As shown in Figure 16, in the configuration of the projection optical system of this embodiment 6, the lateral aberrations are well corrected in the meridional, sagittal, and 45° azimuth directions. In addition, the wavefront aberration RMS of the i-line, which is the dominant wavelength, is small at 11.2 to 21.3 mλ, and the absolute value of the C17 term component of the Zernike polynomial is also small at -22.0 to 14.0 mλ, and these aberrations are also well corrected.

As described above, in a projection optical system, generally, the diffracted light from a vertical/horizontal pattern (line) on the object plane is hardly affected by the C17 term component of the Zernike polynomial, but the diffracted light from a diagonal pattern (line) on the object plane is greatly affected by the C17 term component. As a result, focus differences and line width differences are caused between the diagonal pattern and the vertical/horizontal pattern, and the line width uniformity within the screen may decrease. According to the projection optical system of the above-mentioned Examples 1 to 6 of the present invention, by configuring the concave reflecting surface M1 to satisfy the formula (1), the absolute value of the C17 term component of the Zernike polynomial can be reduced even with a high NA, so that the decrease in the contrast of the projected image can be reduced. In addition, the focus differences and line width differences occurring between the diagonal pattern and the vertical/horizontal pattern can also be reduced, so that the deterioration of the line width uniformity within the screen (i.e., on the exposed substrate) can also be prevented. In another aspect, in the projection optical systems of the first to sixth embodiments of the present invention, by configuring the concave reflecting surface M1 to satisfy the formula (4), the aspheric shape of the concave reflecting surface M1 can be measured with a spherical interferometer. Therefore, a large capital investment for measuring the aspheric shape of the concave reflecting surface M1 is not required, which can be advantageous in terms of capital investment costs.

<Embodiments of Exposure Apparatus>
An embodiment of an exposure apparatus having a projection optical system according to the present invention will be described. FIG. 17 shows a schematic configuration example of a scanning exposure apparatus EX of this embodiment. The scanning exposure apparatus EX of this embodiment includes an illumination optical system IO that illuminates an original M, a projection optical system PO that projects a pattern of the original M onto a substrate P (plate) P, and a controller CNT. The original M is placed on the object plane of the projection optical system PO, and is held and driven by an original stage MS. The substrate P is placed on the image plane of the projection optical system PO, and is held and driven by a substrate stage PS. The controller CNT is composed of a computer (information processing device) having a processor such as a CPU (Central Processing Unit) and a storage unit such as a memory, and controls each unit of the scanning exposure apparatus EX to control the scanning exposure of the substrate P.

The scanning exposure apparatus EX is configured to project the pattern of the original M illuminated by the illumination optical system IO onto the substrate P using the projection optical system PO while scanning the original M and the substrate P relatively, thereby scanning and exposing the substrate P. The illumination optical system IO illuminates an arc-shaped area on the object plane (original M) as an illumination area. The projection optical system PO projects a portion of the illumination area illuminated by the illumination optical system IO of the pattern provided on the object plane (original M) onto the image plane (substrate P). The projection optical systems described in the above embodiments 1 to 6 can be applied to the projection optical system PO of the scanning exposure apparatus EX.

<Embodiments of a method for manufacturing an article>
The method for manufacturing an article according to an embodiment of the present invention is suitable for manufacturing an article such as a microdevice such as a semiconductor device or an element having a fine structure. The method for 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 using the above-mentioned exposure apparatus (a step of exposing the substrate) and a step of developing (processing) the substrate on which the latent image pattern has been formed in the step. Furthermore, the manufacturing method includes other well-known steps (oxidation, film formation, deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The method for manufacturing an article according to the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article compared to conventional methods.

Summary of the embodiment
The disclosure of this specification includes at least the following projection optical system, exposure apparatus, and method for manufacturing an article.
(Item 1)
1. A projection optical system that projects a light beam from an illumination area located off an optical axis on an object plane onto an image plane by passing the light beam through a first refractive optical system, a concave reflecting surface, a second refractive optical system, a convex reflecting surface, the second refractive optical system, the concave reflecting surface, and a third refractive optical system in this order,
the numerical aperture of the projection optical system is 0.11 or more;
each of the concave reflecting surface, the first refractive optical system, the second refractive optical system, and the third refractive optical system has an aspheric surface;
the concave reflective surface is configured to satisfy a predetermined condition for a light beam emitted from an end point of a line at which a plane that bisects the illumination area so as to include the optical axis intersects with the illumination area and enters the concave reflective surface,
The predetermined condition is that, when the paraxial radius of curvature of the concave reflecting surface is defined as positive, in a function expressing the local radius of curvature of the concave reflecting surface with the position of the concave reflecting surface in the meridional direction as a variable, a differential value Tp at the position where the principal ray of the light beam is incident, and a maximum value Tm of the differential value in the position range where the meridional upper ray of the light beam is incident are
Tm-Tp>0
A projection optical system comprising:
(Item 2)
The predetermined condition is that the differential value Tp and the maximum value Tm are
Tm-Tp>0.0004
2. The projection optical system according to claim 1, further comprising the condition:
(Item 3)
3. The projection optical system described in item 1 or 2, characterized in that the concave reflective surface is configured to satisfy the specified condition for each of a first light beam that is emitted from one of two end points of the line and enters the concave reflective surface, and a second light beam that is emitted from the other of the two end points and enters the concave reflective surface.
(Item 4)
When the paraxial radius of curvature of the concave reflecting surface is defined as positive, the predetermined condition is as follows:
a differential value Tpa at a position where a principal ray of the first light flux is incident in the function, and a maximum value Tma of the differential value in a position range where a meridional upper ray of the first light flux is incident satisfy a condition that (Tma-Tpa>0);
a differential value Tpi at a position where a principal ray of the second light flux is incident in the function, and a maximum value Tmi of a differential value in a position range where a meridional upper ray of the second light flux is incident satisfy a condition that (Tmi-Tpi>0);
4. The projection optical system according to item 3, comprising:
(Item 5)
The predetermined condition is that the differential value Tpa for the first light flux and the differential value Tpi for the second light flux are
|Tpa-Tpi|<0.001
5. The projection optical system according to item 4, further comprising the condition that:
(Item 6)
6. The projection optical system according to any one of items 1 to 5, wherein an aspheric sag of the concave reflecting surface with respect to an approximate spherical surface determined by the optical axis and an effective diameter is smaller than 10 μm.
(Item 7)
The projection optical system described in any one of items 1 to 6, characterized in that the second refractive optical system has a region on the concave reflecting surface for compensating for a change in the differential value of the function in a range from a position where the principal ray of the light beam is incident to a position where the meridional marginal ray of the light beam is incident.
(Item 8)
8. The projection optical system according to claim 1, wherein the second refractive optical system is a meniscus lens.
(Item 9)
9. The projection optical system according to any one of items 1 to 8, wherein the projection optical system is a unity magnification system.
(Item 10)
10. The projection optical system according to claim 1, wherein the illumination area is an arc-shaped area.
(Item 11)
An exposure apparatus for exposing a substrate, comprising:
an illumination optical system for illuminating the original;
A projection optical system according to any one of items 1 to 10,
Equipped with
an exposure apparatus, wherein the projection optical system projects a pattern of the original, which is arranged on an object plane, onto the substrate, which is arranged on an image plane;
(Item 12)
an exposure step of exposing a substrate using the exposure apparatus according to item 11;
a processing step of processing the substrate exposed in the exposure step;
a manufacturing process for manufacturing an article from the substrate processed in the processing process;
A method for producing an article, comprising:

The invention is not limited to the above-described embodiment, and various modifications and variations are possible without departing from the spirit and scope of the invention. Therefore, the following claims are appended to disclose the scope of the invention.

PO: projection optical system, OP: object plane, IP: image plane, M1: concave reflective surface, M2: convex reflective surface, L1: first refractive optical system, L2: second refractive optical system, L3: third refractive optical system System, DM: Trapezoidal mirror (plane mirror)

Claims (12)

1. A projection optical system that projects a light beam from an illumination area located off an optical axis on an object plane onto an image plane by passing the light beam through a first refractive optical system, a concave reflecting surface, a second refractive optical system, a convex reflecting surface, the second refractive optical system, the concave reflecting surface, and a third refractive optical system in this order,
the numerical aperture of the projection optical system is 0.11 or more;
each of the concave reflecting surface, the first refractive optical system, the second refractive optical system, and the third refractive optical system has an aspheric surface;
the concave reflective surface is configured to satisfy a predetermined condition for a light beam emitted from an end point of a line at which a plane that bisects the illumination area so as to include the optical axis intersects with the illumination area and enters the concave reflective surface,
The predetermined condition is that, when the paraxial radius of curvature of the concave reflecting surface is defined as positive, in a function expressing the local radius of curvature of the concave reflecting surface with the position of the concave reflecting surface in the meridional direction as a variable, a differential value Tp at the position where the principal ray of the light beam is incident, and a maximum value Tm of the differential value in the position range where the meridional upper ray of the light beam is incident are
Tm-Tp>0
A projection optical system comprising: The predetermined condition is that the differential value Tp and the maximum value Tm are
Tm-Tp>0.0004
2. The projection optical system according to claim 1, further comprising the condition that: The projection optical system according to claim 1, characterized in that the concave reflecting surface is configured to satisfy the predetermined condition for each of a first light beam emitted from one of the two end points of the line and incident on the concave reflecting surface, and a second light beam emitted from the other of the two end points and incident on the concave reflecting surface. When the paraxial radius of curvature of the concave reflecting surface is defined as positive, the predetermined condition is as follows:
a differential value Tpa at a position where a principal ray of the first light flux is incident in the function, and a maximum value Tma of the differential value in a position range where a meridional upper ray of the first light flux is incident satisfy a condition that (Tma-Tpa>0);
a differential value Tpi at a position where a principal ray of the second light flux is incident in the function, and a maximum value Tmi of a differential value in a position range where a meridional upper ray of the second light flux is incident satisfy a condition that (Tmi-Tpi>0);
4. The projection optical system according to claim 3, comprising: The predetermined condition is that the differential value Tpa for the first light flux and the differential value Tpi for the second light flux are
|Tpa-Tpi|<0.001
5. The projection optical system according to claim 4, further comprising the condition that the following is satisfied: The projection optical system according to claim 1, characterized in that the aspheric sag of the concave reflecting surface with respect to an approximate spherical surface determined by the optical axis and the effective diameter is less than 10 μm. The projection optical system according to claim 1, characterized in that the second refractive optical system has an area on the concave reflecting surface for compensating for changes in the differential value of the function in the range from the position where the principal ray of the light beam is incident to the position where the meridional marginal ray of the light beam is incident. The projection optical system according to claim 1, characterized in that the second refractive optical system is a meniscus lens. The projection optical system according to claim 1, characterized in that the projection optical system is a unity magnification system. The projection optical system according to claim 1, characterized in that the illumination area is an arc-shaped area. An exposure apparatus for exposing a substrate, comprising:
an illumination optical system for illuminating the original;
A projection optical system according to any one of claims 1 to 10,
Equipped with
an exposure apparatus, wherein the projection optical system projects a pattern of the original, which is arranged on an object plane, onto the substrate, which is arranged on an image plane; an exposure step of exposing a substrate using the exposure apparatus according to claim 11;
a processing step of processing the substrate exposed in the exposure step;
a manufacturing process for manufacturing an article from the substrate processed in the processing process;
A method for producing an article, comprising: