JPH10189428A - Illumination optical apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination optical apparatus which does not spoil the uniformity of an illumination distribution and which can correct telecentricity. SOLUTION: An illumination optical apparatus is provided with secondary- light-source formation means 1, 2 which form a secondary light source on the basis of a luminous flux from a light source, with a multiple-light-source-image formation means 32 which forms many light-source images on the basis of a luminous flux from the secondary light source, with condenser optical systems 34, 35 which condense luminous fluxes from the many light-source images and by which a face R to be irradiated is illuminated telecentrically and with a relay optical system 31 by which the position of the secondary light source and positions of the many light-source images are conjugated. Then, the secondary light source, the relay optical system and the multiple-light-source-image formation means can be moved integrally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination optical device, and more particularly to an illumination optical device suitable for an illumination system of a projection exposure apparatus used in a lithography process for manufacturing, for example, a semiconductor device or a liquid crystal display device.

[0002]

2. Description of the Related Art Projection exposure for transferring a pattern of a mask (reticle or photo mask) onto a substrate (wafer, glass plate, etc.) when manufacturing a semiconductor element or a liquid crystal display element by using a photolithography technique. The device is being used. 2. Description of the Related Art In recent years, in a projection exposure apparatus, high precision of pattern superimposition is required along with miniaturization of a transfer pattern, and it is required to reduce a projection magnification error within a focal depth of a pattern transfer image. In view of this, the present applicant has proposed, in Japanese Patent Publication No. 7-85140 (JP-A-62-123423), an illumination optical device that can provide an illumination light beam having good telecentricity on the image side. ing.

In the conventional illumination optical device proposed in the above-mentioned publication, a large number of light source images are formed on the exit end face of a fly-eye lens based on a light beam from a light source, and the formed large number of light source images are used in a projection optical system. It is configured to be optically at infinity when viewed from the image plane. Further, each entrance end face of each lens element constituting the fly-eye lens is configured to be substantially conjugate with the image plane of the projection optical system. Therefore, the light beam incident on the fly-eye lens from the light source is wavefront divided into the same number of regions as the number of lens elements constituting the fly-eye lens, and after forming a large number of light source images, the light beams from the large number of light source images are The mask is superimposedly illuminated via the condenser optical system. Thus, the illumination optical device constitutes a so-called telecentric optical system in which a principal ray is incident on the image plane of the projection optical system in parallel with the optical axis.

However, since the spatial light intensity distribution of the light beam from the light source entering the fly-eye lens is not uniform, even if the parallelism between the principal ray and the optical axis on the image side is maintained,
The reason why the direction of the center of gravity of the light beam does not coincide with the direction of the principal ray is as described in the above-mentioned publication. That is, a shift in telecentricity occurs due to the non-uniformity of the intensity distribution of the light beam incident on the fly-eye lens. For this reason, in the illumination optical device disclosed in the above publication,
The fly-eye lens is moved along the optical axis direction and the optical axis vertical direction. Due to the movement of the fly-eye lens, it is possible to obtain good telecentricity on the image side of the projection optical system even when the intensity distribution of the light beam incident on the fly-eye lens is not uniform.

[0005]

Generally, in a projection exposure apparatus, in order to expose a pattern on a substrate to be exposed at a high resolution, the uniformity of illuminance distribution in an illumination area on a mask and an exposure area on the exposure substrate is required. It needs to be raised. However, when the fly-eye lens is moved to correct the telecentricity, illuminance unevenness occurs with the movement of the fly-eye lens. The occurrence of illuminance non-uniformity due to the movement of the fly-eye lens is due to the non-uniform intensity distribution of the light beam incident on the fly-eye lens. That is, when the fly-eye lens moves, the light quantity distribution of the light beam cross section received by the incident end face of the fly-eye lens changes, and as a result, the uniformity of the illuminance distribution on the mask and on the substrate to be exposed fluctuates.

Further, in this case, the fact that the amount of movement of the fly-eye lens is not proportional to the amount of change in telecentricity makes it difficult to correct the telecentricity by moving the fly-eye lens. The fact that the amount of movement of the fly-eye lens is not proportional to the amount of change in telecentricity is also due to the non-uniform intensity distribution of the light beam incident on the fly-eye lens. That is, when the fly-eye lens moves, the light amount distribution of the cross section of the light beam received by the incident end face of the fly-eye lens changes, and a number of light source image planes formed on the exit end face of the fly-eye lens corresponding to this change in the light amount distribution. Changes in the light amount distribution. As a result, the center of gravity of the light amount changes with respect to the fly-eye lens, and the amount of movement of the fly-eye lens and the amount of change in the direction of the center of gravity of the light amount of the illumination light on the image side of the projection optical system do not show a simple correspondence. I will.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an illumination optical apparatus capable of correcting telecentricity without deteriorating the uniformity of the illuminance distribution. . It is still another object of the present invention to provide an illumination optical device in which the amount of movement of the fly-eye lens and the amount of change of the illumination light flux on the image side in the direction of the center of gravity are substantially proportional to facilitate correction of telecentricity.

[0008]

According to a first aspect of the present invention, there is provided a multi-light source image forming means for forming a plurality of light source images based on a light beam from a light source. A condenser optical system for converging light beams from the multiple light source images formed through the forming means and illuminating the irradiated surface telecentrically, and the position of the light source and the multi-source image forming means A relay optical system for conjugating the positions of the plurality of light source images to be formed, without impairing the uniformity of the illuminance distribution on the surface to be irradiated; The light source, the relay optical system, and the multiple light source image forming means are arranged along the optical axis direction or a direction perpendicular to the optical axis to correct a deviation in telecentricity caused by the non-uniformity of the intensity distribution. Can be moved together To provide an illumination optical apparatus characterized by.

Further, in the second invention, a secondary light source forming means for forming a secondary light source based on a light beam from the light source, and a secondary light source formed through the secondary light source forming means are provided. A multi-source image forming means for forming a plurality of light source images based on the light flux of the light source; and condensing the light flux from the plurality of light source images formed through the multi-source image forming means to form an irradiation surface. A condenser optical system for telecentric illumination, and the positions of the secondary light sources formed through the secondary light source forming means and the positions of the multiple light source images formed through the multiple light source image forming means. And a relay optical system for conjugating the illuminated light, and without deteriorating the uniformity of the illuminance distribution on the surface to be illuminated, the telephoto caused by the non-uniformity of the intensity distribution of the light beam incident on the multi-source image forming means. Compensate for Centricity Therefore, the illumination optical device is characterized in that the secondary light source, the relay optical system, and the multi-source image forming means are integrally movable along an optical axis direction or a direction perpendicular to the optical axis. provide. According to a preferred aspect of the second invention, the secondary light source forming means includes a light guide, and a light source image forming means for forming a light source image at an incident end of the light guide based on a light beam from the light source. And the secondary light source is formed at an emission end of the light guide.

Further, according to the third invention, the secondary light source forming means for forming a plurality of secondary light sources based on the light flux from one or more light sources, and the secondary light source forming means A plurality of light source image forming means for forming a plurality of light source images based on light fluxes from each of the plurality of secondary light sources formed through the plurality of light source image forming means; A plurality of condenser optical systems for condensing light beams from the large number of light source images formed respectively and illuminating each region of the irradiated surface telecentrically, and the secondary light source forming means. A plurality of relay optical systems for respectively conjugate the positions of the plurality of secondary light sources and the positions of the plurality of light source images respectively formed through the plurality of multiple light source image forming means. The irradiation surface Each secondary light source corresponding to each other is corrected without compromising the uniformity of the illuminance distribution in the area, and correcting the telecentricity shift caused by the non-uniformity of the intensity distribution of the light flux incident on each light source image forming means. And an illumination optical device, wherein each of the relay optical systems and each of the multiple light source image forming means are integrally movable along an optical axis direction or a direction perpendicular to the optical axis.

According to a preferred aspect of the third invention, the secondary light source forming means has the same number of incident ends as the one or more light sources, and has the same number as the plurality of multi-source image forming means. A multi-branch light guide having one or more light-emitting ends, and one or two light source images formed at each light-receiving end of the multi-branch light guide based on a light beam from each of the one or more light sources. One or more light sources and the same number of light source image forming means are provided, and each secondary light source is formed at each emission end of the multi-branch light guide.

[0012]

As described above, in the illumination optical device of the present invention, for example, a secondary light source formed on the exit end face of a light guide, a relay optical system, and a multi-source image such as a fly-eye lens The forming means is integrally movable along the optical axis direction or a direction perpendicular to the optical axis. Therefore, even if the fly-eye lens is moved along the optical axis direction or perpendicular to the optical axis in order to correct the deviation of the telecentricity due to the non-uniformity of the intensity distribution of the light beam incident on the fly-eye lens, The intensity distribution of the light beam incident on the eye lens is unchanged. As a result, it is possible to satisfactorily correct the telecentricity without impairing the uniformity of the illuminance distribution on the irradiated surface. Further, even if the fly-eye lens is moved, the intensity distribution of the light beam incident on the fly-eye lens remains unchanged, so that the displacement amount of the light quantity center of gravity of the light beam can be made almost proportional to the movement amount of the fly-eye lens. As a result, it is easy to predict the amount of movement of the fly-eye lens required for the correction of the telecentricity, and the workability relating to the correction of the telecentricity is improved.

An embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram schematically showing a configuration of an illumination optical device according to a first embodiment of the present invention. In FIG. 1, the x-axis is along the optical axis AX, the y-axis is parallel to the plane of FIG. 1 in a plane perpendicular to the optical axis AX, and the y-axis is perpendicular to the plane of FIG. 1 in a plane perpendicular to the optical axis AX. The z-axis is set respectively.
FIG. 2A is a perspective view showing a configuration of each lens element 32a constituting the fly-eye lens 32 of FIG. 1, and FIG. 2B is a diagram showing light at an incident end face C of the fly-eye lens 32 of FIG. It is a figure showing an intensity distribution. This embodiment shows an example in which the illumination optical device is applied to a projection exposure apparatus for manufacturing a semiconductor element, a liquid crystal display element, and the like.

In the illumination optical device shown in FIG.
Is composed of an elliptical mirror 12 and a light source 11 arranged at a first focal position of the elliptical mirror 12. As the light source 11, for example, g-line (436 nm), i-line (365n)
A mercury lamp or the like that outputs a light beam such as m) and h rays (407 nm) can be used. The light beam from the light source 11 is condensed by the elliptical mirror 12 so that
To form a light source image. The incident end face of the light guide 21 is positioned at the second focal position A of the elliptical mirror 12, and
The light flux from the light source image formed at the second second focus position A enters the light guide 21. The light beam incident on the light guide 21 propagates inside the light guide 21 and forms a secondary light source on the emission end face B. The light beam from the secondary light source formed on the exit end face B of the light guide 21 is supplied to the subsequent illumination optical system 3. As described above, the light supply system 1 and the light guide system 2 constitute a secondary light source forming unit for forming a secondary light source.

The light beam incident on the illumination optical system 3 from the exit end surface B of the light guide 21 is converted into a parallel light beam by the collimator lens 31 and is incident on the incident end surface C of the fly-eye lens 32. As shown in FIG. 2A, the fly-eye lens 32 is configured by densely arranging lens elements 32a having a rectangular cross-sectional shape vertically and horizontally in a plane perpendicular to the optical axis AX. Each lens element 32a is configured such that its air-equivalent length and the focal length match. Therefore, the parallel light beam incident on the fly-eye lens 32 is condensed by each lens element 32a, and forms a light source image on the exit side of each lens element 32a. That is, the exit end face D of the fly-eye lens 32 has a large number (the lens element 32
(same number as a).

Light beams from a large number of light source images formed on the exit end face D of the fly-eye lens 32 are converted into light beams having a circular cross-sectional shape by a circular aperture stop 33 positioned immediately after this, and are condensed into a condenser lens system (34). , 35). In addition, the condenser lens system (34, 35)
Since the pattern surface R of the mask, which is the surface to be irradiated, is positioned almost at the rear focal position of the fly-eye lens 3
The entrance end face C of each lens element 32a and the irradiated surface R have a substantially conjugate relationship. Therefore, the luminous flux from the multiple light source images formed on the exit end face D of the fly-eye lens 32 passes through the condenser lens system (34, 35).
Irradiates the irradiated surface R in a superimposed manner, and the illuminance distribution on the irradiated surface R shows good uniformity. Further, the circular aperture stop 33 disposed immediately after the exit end face D of the fly-eye lens 32 includes a condenser lens system (3
4, 35) are arranged substantially at the front focal plane. Therefore, the luminous flux restricted via the circular aperture stop 33 is converted into a parallel luminous flux by the action of the condenser lens system (34, 35), and irradiates the irradiated surface R.

The irradiated surface (mask pattern surface) R uniformly illuminated by the light beams from the illumination optical system 3 (31 to 35)
Is formed with a predetermined circuit pattern. Therefore, the light transmitted through the pattern surface R forms a circuit pattern image via the projection optical system 4 on the exposure surface W of the substrate to be exposed, which is disposed at a position conjugate with the irradiation surface R. The mask R serving as a surface to be irradiated is held on a mask stage RS that is movable in a two-dimensional direction (y-direction and z-direction) along a plane perpendicular to the plane of FIG. The exposure substrate W can be moved in a two-dimensional direction (y-direction and z-direction) along a plane perpendicular to the plane of FIG.
S is held.

The position of the mask stage RS is measured by a position measurement system IF1 such as an interferometer, and the movement of the mask stage RS is performed by a drive system MS1 such as a motor. The control is performed by the drive system M based on the measurement value from the position measurement system IF1.
This is achieved by a control system CS1 that supplies a drive output to S1. The position of the substrate stage WS is measured by a position measurement system IF2 such as an interferometer, and the movement of the substrate stage WS is performed by a drive system MS2 such as a motor. Finally, the position of the substrate stage WS is controlled by the position Measurement IF
This is achieved by the control system CS1 which supplies a drive output to the drive system MS2 based on the measurement value from the control system CS2. Further, the substrate stage WS is moved in the optical axis direction (x direction) of the projection optical system 4 via a drive system (not shown) controlled by the control system CS1.
Is provided so as to be movable.

Above the substrate stage WS, a projection system AF1 of an autofocus system and a detection system AF2 of an autofocus system are provided, and the light from the projection system AF1 is inclined with respect to the substrate W to be exposed. The light is reflected from the surface of the substrate W to be exposed, and the light reflected from the surface of the substrate W to be exposed is received by the detection system AF2. Can be detected. Therefore, based on the detection information from the detection system AF2, the control system C
S1 controls the position of the substrate stage WS along the optical axis direction (x direction) of the projection optical system 4 via a drive system (not shown).

In the projection optical system 4, by arranging the exit pupil plane E at an optically infinite position when viewed from the image plane,
It has a telecentric configuration on the image side. In the projection optical system 4, an aperture stop is arranged on the exit pupil plane E, and the aperture stop defines the numerical aperture of the projection optical system 4. At this time, the numerical aperture NAi of the illumination system (1-3) on the image plane W
And the numerical aperture NAu of the projection optical system 4 on the image plane W,
The relationship is set so as to satisfy the following expression (1).

0 <NAi / NAu <1 (1)

By the way, even if the principal ray of a light beam incident on a certain point on the image plane W is perpendicular to the image plane W, the direction of the center of gravity of the light beam is generally perpendicular to the image plane W. do not become. This is based on a plurality of light source images formed on the exit end face D of the fly-eye lens 32 and formed into a circular cross-sectional shape by the circular aperture stop 33 disposed immediately behind the fly-eye lens 32, on the exit pupil plane E of the projection optical system 4. This is because the center of gravity of the light quantity of the formed transfer image does not coincide with the optical axis.

The parallel light beam incident on the incident end face C of the fly-eye lens 32 is
Of light intensity emitted from the light guide 21
Due to manufacturing errors and lens misalignment
For example, non-uniform (non-uniform) as shown in FIG.
It exhibits a light intensity distribution. Assuming that the intensity distribution of the light beam incident on the incident end face C of the fly-eye lens 32 is I1 (y, z), the intensity distribution I2 of the light beam on the circular aperture stop 33 is I2.
_{Y, Z} (y, z) is represented by the following equation (2).

I 2 _{Y, Z} (y, z) = I 1 (y−Y / β, z−Z / β) (2) where β: the distance between the incident end face C of the fly-eye lens 32 and the image plane W Imaging magnification Y: y coordinate of incident point P on image plane W Z: z coordinate of incident point P on image plane W

According to the above equation (2), the circular aperture stop 33
It can be seen that the intensity distribution of the upper light beam changes depending on the coordinates of the incident point P on the image plane W. Since the detailed description of the expression (2) is sufficiently described in the aforementioned gazette (Japanese Patent Publication No. 7-85140), the duplicate description will be omitted in this specification. By the way, in this specification, one point P of the image plane W
The unsatisfactory amount of the telecentricity of the light beam incident on (Y, Z) is determined by the amount of light beam centroid, which is the amount of deviation of the light beam centroid direction of the light beam incident on one point P (Y, Z) from the normal direction of the image plane W. Defined as G. Further, the light quantity center-of-gravity shift G is expressed by the following equation (3) using the cosine of the direction of the light quantity center of gravity in the y direction and the z direction.

[0024]

G = U _y + iU _z ≡U _g exp (iφ) (3) where U _{y is the} cosine of the direction of the center of gravity of the light amount in the y direction U _{z is the} cosine of the direction of the center of gravity of the light amount in the z direction U _G = (U _y ² + U _z ² ) ^1/2 φ = tan ⁻¹ (U _z / U _y ) i ² = −1

In this case, the displacement G (Y, Z) of the light quantity of the light beam incident on one point P (Y, Z) on the image plane W is expressed by the following equation (4).

(Equation 4) Here, σ: all light beams incident on one point (Y, Z) on the image plane W (corresponding to the aperture range of the circular aperture stop 33)

In addition, I2′Y _{, Z} in the above equation (4)
(U, φ) is approximately expressed by the following equation (5), where f is the combined focal length of the condenser lens system (34, 35) and the projection optical system 4.

I2′Y _{, Z} (U, φ) = I2Y _{, Z} (fUcosφ, fUsinφ) (5)

As in this embodiment, when the exit pupil plane E of the projection optical system 4 is located at an optically infinite position when viewed from the image plane W, the light intensity distribution I1 on the entrance end face C of the fly-eye lens 32 If (y, z) is constant without depending on y and z, that is, if a light beam having a uniform light intensity distribution is incident on the incident end face C of the fly-eye lens 32, the light amount centroid deviation G is always 0. And good telecentricity can be obtained. However, in general, fly-eye lens 3
2, the light intensity distribution I1 (y, z) at the incident end face C is
As shown in FIG. 2B, since the distance is non-uniform depending on the distance from the optical axis AX (that is, y and z), good telecentricity cannot be obtained. Even if the light intensity distribution I1 (y, z) is symmetric with respect to the optical axis AX,
The value of the light amount center of gravity shift G does not become zero.

Hereinafter, the light intensity distribution I1 (y, z) is expressed by the optical axis A
A description will be given of the fact that the value of the light quantity center-of-gravity deviation G does not become 0 even when the image is symmetric with respect to X. First, it is assumed that a light intensity distribution I1 (y, z) symmetric with respect to the optical axis AX is represented by the following equation (6).

I 1 (y, z) = a (y ² + z ² ) + I ₀ (6) where a: a constant other than ₀ I ₀ : light intensity on the optical axis AX

If δ _y = Y / β and δ _z = Z / β, the following equation (7) can be obtained by a simple calculation.

(Equation 7) Here, φ = tan ⁻¹ (δ _z / δ _y ) where, r: aperture radius of the circular aperture stop 33

From equation (7), the magnitude of G is equal to the origin (Y,
Z) = (0,0), so that G on the y-axis
Even if (Y, 0), the character is maintained.

(Equation 8)

Referring to equation (7.5), when Y = 0, G = 0
Where G 、 0 except for Y = 0. Especially δ _y
When ≪r, equation (7) can be expressed as the following equation (8).

(Equation 9) Equation (8) above indicates that the transfer magnification of the pattern on the irradiation surface R by the projection optical system 4 changes in proportion to the defocus of the exposure surface W.

In this case, the exit end portion (ie, the secondary light source) of the light guide 21, the collimator lens 31, the fly-eye lens 32, and the circular aperture stop 33 are integrally displaced by a predetermined distance along the optical axis direction. As a result, the light amount gravity center shift G can be corrected to almost zero. Assuming that the displacement amount at this time is Δx, a point P on the image plane W of the projection optical system 4 is obtained.
The change amount ΔVy of the principal ray at (Y, 0) is approximately expressed by the following equation (9).

ΔVy = YΔx / f ² (9)

Giving Δx such that ΔVy in the equation (9) matches the light quantity center-of-gravity shift G given in the equation (8) fulfills the above-mentioned purpose. Then, since Y can be eliminated by the above equations (8) and (9), the relationship shown in the following equation (10) is obtained.

[Equation 11]

As described above, the displacement Δ obtained by the equation (10)
By moving the exit end portion of the light guide 21, the collimator lens 31, the fly-eye lens 32, and the circular aperture stop 33 along the optical axis direction by x, the light amount center of gravity G is made substantially zero, and the telecentricity is corrected. It can be performed. In order to establish a simple proportional relationship between ΔVy and Δx as shown in Expression (9), the light intensity distribution on the circular aperture stop 33 does not change with the movement of the fly-eye lens 32. It is necessary. In the present embodiment, since the partial system from the exit end of the light guide 21 to the fly-eye lens 32 (including the circular aperture stop 33) is integrally moved, the above-described condition is satisfied.

The above relationship will be described in some detail.
For simplicity, the dimension of the light intensity distribution I1 (y, z) on the circular aperture stop 33 originally having a two-dimensional spread is set to 1
Lowered and handled as light intensity distribution I (y). In this case, the light amount center-of-gravity deviation Gy is expressed by the following equation (11).

(Equation 12)

When the subsystem from the exit end of the light guide 21 to the fly-eye lens 32 is moved integrally, the light intensity distribution I (y) of the light beam incident on the fly-eye lens 32 is Not affected by movement. Now, assuming that the sub-system including the fly-eye lens 32 is moved in the y-direction by ξ, and assuming a coordinate system y ′ stuck to the fly-eye lens 32, a new light quantity center of gravity shift G
y ′ is represented by the following equation (12).

(Equation 13)

Since y ′ = y−ξ, the above equation (12)
Is represented by the following equation (13).

[Equation 14]

In equation (13), ξ is replaced by Δy,
Assuming that ΔVy = Gy′−Gy, this matches the equation (16) described later. When the subsystem including the fly-eye lens 32 is moved by Δx in the optical axis AX direction, ξ is replaced as follows.

１５ = Δx · tanθ ≒ Δx · sinθ ≒ Δx · Y / f (13.5) If Expression (13.5) is substituted into Expression (13), this matches Expression (9). That is, the exit end of the light guide 21, the collimator lens 31, and the circular aperture stop 33 are moved together with the fly-eye lens 32 so that I (y ') is not affected by the movement of the fly-eye lens 32. Thus, the amount of displacement of the center of gravity of the light amount can be made substantially proportional to the amount of movement of the fly-eye lens 32. In this case, it is easy to predict the amount of movement of the fly-eye lens 32 required for the correction of the telecentricity, so that the workability relating to the correction of the telecentricity is improved. Further, even if the fly-eye lens 32 is moved to correct the telecentricity, the light intensity distribution received by the fly-eye lens 32 is unchanged, so that the illuminance distribution on the irradiated surface R and the exposed surface W changes. Nothing. As a result, telecentricity can be corrected without deteriorating good uniformity of the illuminance distribution.

Next, as an example of a light intensity distribution that is not symmetrical with respect to the optical axis AX, a light intensity distribution I expressed by the following equation (14):
Consider a case where the light beam of 1 (y, z) is incident on the fly-eye lens 32.

Equation 16] I1 (y, z) = ay + I 0 (14) In this case, the light quantity gravity center shift G (Y, Z) of the light beam incident on the P 1 point in the image plane W (Y, Z) have the formula It is represented by (15).

G (Y, Z) = a / {4f (I ₀ / r ² −aδ / r ² )}｝ ar ² / (4fI ₀ ) = constant (15)

In equation (15), an approximate calculation based on δ≪r is performed. Equation (15) indicates that the transfer image of the pattern on the irradiation surface R by the imaging optical system 4 moves in proportion to the defocus of the exposure surface W. In this case, the exit end portion of the light guide 21, the collimator lens 31, the fly-eye lens 32, and the circular aperture stop 33 are
By integrally displacing a predetermined distance along the direction perpendicular to the optical axis AX (in this case, the y direction), the light amount center of gravity shift G can be corrected to zero.

As described above, even when the fly-eye lens 32 is moved, the light intensity distribution of the light beam received by the fly-eye lens 32 is unchanged. Therefore, from the same consideration as in Expression (13), if the displacement amount is Δy, the change amount ΔVy of the principal ray in the y direction is approximately expressed by Expression (16).

ΔVy = Δy / f (16)

Accordingly, the displacement amount Δy required to correct the light quantity center-of-gravity deviation G is obtained from the equations (15) and (16).
Is obtained by the relationship shown in the following equation (17).

Δy = −ar ² / (4I ₀ ) (17) As described above, the light guide 21, the collimator lens 31, the fly-eye lens 32, and the circle are formed by the displacement amount Δy obtained by the equation (17). By moving the aperture stop 33 along the direction perpendicular to the optical axis (the y direction), the displacement G of the light quantity center can be made substantially zero, and the correction of the telecentricity can be performed.

In this case, similarly, the fly-eye lens 32
Illuminated surface R and exposed surface W when moving the subsystem including
, The telecentricity can be corrected without deteriorating good uniformity of the illuminance distribution. Also, as shown in equation (16),
Since the amount of displacement of the center of gravity of the light amount is substantially proportional to the amount of movement of the fly-eye lens 32, the work relating to the correction of the telecentricity becomes easy. Thus, in the first embodiment, the optimum moving amount for correcting the telecentricity is obtained from the equations (9) and (16) according to the remaining unsatisfactory amounts of the telecentricity ΔVy and ΔVz. By moving the exit end portion of the light guide 21, the collimator lens 31, the fly-eye lens 32, and the circular aperture stop 33 integrally by the determined moving amount, a good telephoto can be obtained without deteriorating the uniformity of the illuminance distribution. You can get Centricity.

In the above, the exit end portion of the light guide 21, the collimator lens 31, the fly-eye lens 32 as an optical integrator, and the aperture stop 33 are integrally moved in the direction of the optical axis or in the direction orthogonal to the optical axis. The example of correcting the telecentricity of the illumination optical system has been described above. Next, automatic correction of the telecentricity of the illumination optical system will be described. As shown in FIG. 1, at a position close to the substrate holder of the substrate stage WS, that is, at one end of the substrate stage WS, a large number of tests formed on a test mask TR, which will be described later, disposed on the object plane of the projection optical system 4. A spatial image position detector PS for measuring the relative position of the image of the pattern TP is provided.

As shown in FIG. 4, the aerial image position detecting section PS includes a parallel plane plate 100 on which a predetermined knife edge pattern is formed, and a light amount detector 101 disposed immediately after the parallel plane plate 100. It is configured. Then, as shown in FIG. 5, the transmission area 100a is formed on the surface of the parallel plane plate 100 in a direction orthogonal to each scanning direction (y direction, z direction).
An L-shaped knife edge pattern is formed such that there is a boundary between the light-shielding region 100b and the light-shielding region 100b. That is,
A knife edge pattern having a boundary line along the z direction on the plane parallel plate 100 is used for measurement in the y direction, and a knife edge pattern having a boundary line along the y direction on the plane parallel plate 100 is used for measurement in the z direction. Used for measurement.

Now, a line-and-space pattern (test pattern) having a regular pitch along the y direction
Assuming that the test mask TR having TP is disposed on the object plane of the projection optical system 4, an image of the test pattern TP is formed on the image plane of the projection optical system 4, that is, on the surface of the substrate W. The image of the test pattern TP has a spatial image intensity distribution along the y direction as shown in FIG. The control system CS1 includes a detection system AF of an autofocus system.
By controlling the position of the substrate stage WS in the x direction so that the output of the substrate stage WS becomes a predetermined output, the substrate stage WS is moved along the y direction via the drive system MS2 to form an image of the test pattern TP. By causing the aerial image position detector PS to scan, the aerial image position detector PS can obtain an integrated light amount distribution of the image of the test pattern TP along the y direction as shown in FIG. In FIG. 7,
The vertical axis is the amount of light, and the horizontal axis is time.

Next, the control system CS1 uses its internal calculation unit based on the position information from the interferometer IF for measuring the position of the stage and the output signal from the aerial image position detection unit PS. By performing a differential operation on the output signal from the spatial image position detecting section PS according to the position of the image position detecting section PS, as shown in FIG. 8, a signal similar to the spatial image intensity distribution shown in FIG. 6 is obtained. , The position of the image of the test pattern TP on the test mask TR in the y direction can be measured.
In the same manner as in the above method, using the test pattern TP for x-direction measurement formed on the test mask TR, an image of the test pattern TP for x-direction measurement is projected.
And a test pattern T for measuring in the x direction
By causing the spatial image position detection unit PS to scan the P image in the z direction, the position of the test pattern TP image in the z direction is finally measured by the arithmetic unit inside the control system CS1. can do.

Next, the telecentricity correction using the above spatial image position detecting section PS will be specifically described.
Now, when a test mask TR having a large number of test patterns TP for measuring the y direction and the z direction is arranged on the object plane of the projection optical system 4, a large number of test masks are formed on the image plane of the projection optical system 4 (the surface of the substrate W). An image of the test pattern TP is formed. Here, on the test mask TR, the y direction and the z direction are set at predetermined positions (P′1, P′2, P′3... P′n) different from each other.
A large number of test patterns TP having light and dark patterns each having a predetermined pitch in each direction are formed, and corresponding different positions (P ″) on the image plane of the projection optical system 4 (the surface of the substrate W). 1, P''2, P''3 ...
Many images of the test pattern TP are formed on P''n).

First, the control system CS1 controls the drive system while controlling the position of the substrate stage WS in the x direction so that the output of the detection system AF2 of the autofocus system becomes the output that becomes the best image plane of the projection optical system. Substrate stage WS via MS2
Is moved along the y direction, and the position P ″ where the image of the test pattern TP at the position P′1 on the test mask TR is formed is formed.
The aerial image position detector PS is set to 1. Next, the control system C
In step S1, the position P ′ of the substrate stage WS is controlled while controlling the position of the substrate stage WS in the x direction such that the output of the detection system AF2 of the autofocus system becomes an output defocused by Δx / 2 from the best image plane of the projection optical system. The spatial image position detector P detects the defocus image of the test pattern TP formed on the
By scanning S in the y direction and the z direction, the position of the defocus image of the test pattern TP formed at the position P ″ 1 is measured.

Thereafter, the control system CS1 adjusts the position of the substrate stage WS in the x direction such that the output of the detection system AF2 of the autofocus system becomes an output defocused by -Δx / 2 from the best image plane of the projection optical system. Is controlled, the spatial image position detection unit PS scans the defocused image of the test pattern TP formed at the position P''1 in the y-direction and the z-direction, respectively. The position of the defocus image of the test pattern TP is measured.

Based on the above measurement results, the control system CS1
Calculates the deviation amounts (Gy1, Gz1) of the telecentricity in the y-direction and the z-direction at the position P ″ 1 on the image plane of the projection optical system 4, respectively, as shown below, I do.

Gy1 = Def (Y) / ΔX Gz1 = Def (Z) / ΔX where Def (Y) is the spatial image position of the test pattern TP due to the defocus ΔX in the optical axis direction of the projection optical system 4. The amount of change in the y direction, Def (Z), is the amount of change in the x direction of the spatial image position of the test pattern TP due to the defocus ΔX of the projection optical system 4 in the optical axis direction.

The control system CS1 includes a test pattern TP formed at each position (P ″ 1, P ″ 2, P ″ 3... P ″ n) on the image plane of the projection optical system 4. Are measured in the y direction and the z direction, respectively, so that the respective positions (P ″ 1, P ″ 2, P ″ 3... P ″ n) in the y direction Telecentricity deviation (Gy1, Gy2 ...
.. Gyn) and each position (P''1, P''2, P''3)
.., P ″ n) in the x direction in the telecentricity (Gx1, Gx2,..., Gxn). Then, the control system CS1 outputs a calculation result regarding the deviation amount of the telecentricity to the signal processing device CS2.

Next, the signal processing device CS2 uses each of the above-described equations (9) and (16) based on the calculation result regarding the amount of deviation of the telecentricity to obtain each telecentricity in the y direction. The shift amount (Gy1, Gy2 ...
... Gxn) and the collimator lens 31 so that the value of each of the deviation amounts (Gx1, Gx2,... Gxn) of the telecentricity in the x direction becomes smaller. Then, the drive amount of the drive system MS3 for moving the fly-eye lens 32 and the aperture stop 33 integrally in the optical axis direction or the direction orthogonal to the optical axis is calculated.

More specifically, the signal processing device CS2 outputs the output information from the control system CS1 (each deviation amount (Gy1, Gy2... Gyn) of the telecentricity in the y direction and the telecommunication in the x direction). Centricity deviation (Gx1, Gx2 ...
.. Gxn)), the constants of A, B, and C when the value of I shown below becomes the minimum value are calculated.

(Equation 21) ∂I / ∂A = 0, ∂I / ∂B = 0, ∂I / ∂C = 0

Here, yk (k = 1, 2, 3,...)
n) is the position on the y coordinate of the aerial image of the test pattern TP formed at each position (P ″ k) on the image plane of the projection optical system 4,
zk (k = 1, 2, 3,... n) is a test pattern T formed at each position (p ″ k) on the image plane of the projection optical system 4.
This is the position on the z coordinate of the aerial image of P. The constants of A, B, and C are calculated from the above-described equations (9) and (16) as A = −ΔX / f ² , B = −ΔY / f, and C = −ΔZ /
f, the signal processing device CS2 includes A, B,
After calculating the constant of C, A = −ΔX / f ² , B = −ΔY
/ F and C = −ΔZ / f, the exit end portion of the light guide 21 and the collimator lens 31, the fly-eye lens 32, and the aperture stop 33 are integrally integrated in the optical axis direction or orthogonal to the optical axis. The drive amount of the drive system MS3 to be moved in the direction to be moved is calculated.

The drive system MS3 integrally connects the exit end of the light guide 21, the collimator lens 31, the fly-eye lens 32 and the aperture stop 33 in the optical axis direction based on the output signal from the signal processing device CS2. Alternatively, it is moved by a predetermined amount in a direction orthogonal to the optical axis. by this,
Good telecentricity is guaranteed on the image plane of the projection optical system 4. After the above operation of adjusting the telecentricity is completed, the test pattern TP disposed on the object plane of the projection optical system 4 is replaced with an exposure mask R on which a predetermined pattern for exposure is formed, and the exposure is performed. A predetermined pattern for exposure on the mask R is projected onto the photosensitive substrate via the projection optical system 4. Thereby, good semiconductor elements and liquid crystal display elements can be manufactured.

FIG. 3 is a diagram schematically showing a configuration of an illumination optical device according to a second embodiment of the present invention. In the second embodiment, as in the first embodiment, an example in which the illumination optical device is applied to a projection exposure apparatus for manufacturing a semiconductor element, a liquid crystal display element, or the like is shown. However, in the second embodiment, one illuminated surface R based on the light fluxes from the three light sources is used.
In order to illuminate the above four areas, three light supply systems 1a
1c, four illumination optical systems 3a to 3d, and four projection optical systems 4a to 4d. The light supply system 1a
1c are the light supply system 1 of the first embodiment and the illumination optical systems 3a to 3c.
3d is the illumination optical system 3 of the first embodiment and the projection optical systems 4a to 4d.
4d has the same configuration as the projection optical system 4 of the first embodiment. The second embodiment will be described below, focusing on the differences from the first embodiment.

In the illumination optical device shown in FIG.
Light sources 11a to 1c positioned at the first focal position 12c
The light beams from 1c form light source images at the second focal positions A1 to A3 of the elliptical mirrors 12a to 12c, respectively. Position A1
The luminous flux from the light source image formed at A3 is divided into positions A1 to A3.
To the multi-branch light guide 22 having an incident end face. The multi-branch light guide 22 has the same number of entrance ends as the number of light sources (three in this embodiment) and the same number of exit ends as the number of illumination optical systems (four in this embodiment). Has a function of distributing a light beam incident on the light emitting end to each of the exit ends. In this way, secondary light sources are formed on the emission end faces B1 to B4 of the multi-branch light guide 22, respectively. Light beams from the secondary light sources formed on the emission end surfaces B1 to B4 of the multi-branch light guide 22 are supplied to the following illumination optical systems 3a to 3d, respectively.

As described above, the illumination optical systems 3a to 3d have the same configuration as the illumination optical system 3 of the first embodiment, and are arranged in parallel with each other. Therefore, the light beams from the secondary light sources formed on the exit end surfaces B1 to B4 of the multi-branch light guide 22 are converted into parallel light beams via the relay optical systems 31a to 31d, and the incident end surfaces C1 of the fly-eye lenses 32a to 32d. To C4. Thus, a large number of light source images are respectively formed on the emission end faces D of the fly-eye lenses 32a to 32d. Fly eye lens 32a ~
Light beams from a large number of light source images formed on the exit end face D of the 32d are restricted by the circular aperture stops 33a to 32d, and then enter the condenser lens systems 34a to 34d, respectively.

The light beams passing through the condenser lens systems 34a to 34d irradiate the four regions on the surface R to be irradiated with each other in a superimposed manner, and the illuminance distribution in each illumination region on the surface R to be irradiated has good uniformity. Will show. Illumination optical system 3a-
Circuit patterns are formed in four illumination regions on the irradiation target surface R uniformly illuminated by 3d. Therefore,
The light transmitted through the four illumination regions on the irradiation target surface R is transmitted through the projection optical systems 4a to 4d to the four exposures on the exposure surface W of the exposure target substrate arranged at a position conjugate with the irradiation target surface R. A circuit pattern image is formed in each area. As described above, the projection optical systems 4a to 4d have the same configuration as the projection optical system 4 of the first embodiment, and are each configured to be telecentric on the image side.

Now, in accordance with the light intensity distribution of the light beam incident on the entrance surfaces C1 to C4 of the fly-eye lenses 32a to 32d in the illumination optical systems 3a to 3d, the telecentricity in each exposure area of the exposure surface W is increased. Collapse occurs as shown in FIG.
As described in the first embodiment. Therefore, in the second embodiment as well, optimal correction of the telecentricity is performed in the illumination optical systems 3a to 3d according to the unsatisfactory amount of the telecentricity in each exposure area of the exposure surface W. As described above, since the illumination optical systems 3a to 3d and the projection optical systems 4a to 4d have the same configuration, the correction of the telecentricity will be described focusing on the illumination optical system 3a and the projection optical system 3a.

First, the exposure surface W corresponding to the illumination optical system 3a
The optimum moving amount for correcting the telecentricity is obtained from Expressions (9) and (16) according to the unsatisfied amounts of telecentricity ΔVy and ΔVz remaining in the upper exposure area. By moving the exit end portion of the multi-branch light guide 22 (that is, the secondary light source), the collimator lens 31a, the fly-eye lens 32a, and the circular aperture stop 33a integrally by the obtained moving amount, a good telephoto is obtained. You can get Centricity. At this time, when the subsystem including the fly-eye lens 32a moves, the illuminance distribution in the corresponding illumination area on the irradiation target surface R and the corresponding exposure area on the exposure surface W does not change. Telecentricity can be corrected without impairing the performance. Further, as shown in Expressions (9) and (16), the displacement of the center of gravity of the light quantity is
Since it is almost proportional to the movement amount of “a”, the work related to the correction of the telecentricity becomes easy.

Thus, the other fly-eye lenses 32b to 32b
In the illumination area and the exposure area corresponding to 32d,
The correction of the telecentricity can be performed individually without deteriorating the good uniformity of the illuminance distribution. Further, as described with reference to FIG. 1, the exit end portions (B1 to B4) of the light guide 22 and the collimator lens (3
1a to 31d), the fly-eye lenses (32a to 32d) as optical integrators and the aperture stop (33, 33a to 33d) are automatically moved integrally with each other in the optical axis direction or the direction orthogonal to the optical axis. Needless to say, the configuration may be adopted.

In the second embodiment, three light supply systems 1a
To 1c have the same configuration, but each light supply system may be set to have a different configuration. Further, the number of light supply systems is not limited to three. Similarly,
The illumination optical systems 3a to 3d and the projection optical systems 4a to 4d have the same configuration, but each illumination optical system and each projection optical system may be set to have different configurations. Furthermore, the number of illumination optical systems and projection optical systems is not limited to four. Further, in each of the above embodiments, an example is shown in which the present invention is applied to an illumination optical device for a projection exposure apparatus. However, the present invention can be applied to other appropriate illumination optical devices.

In each of the above embodiments, the light emitting end portions of the light guides (21, 22), the collimator lenses (31, 31a to 31d), the fly-eye lenses (32, 32a to 32d) as optical integrators, and Although the example in which the aperture stops (33, 33a to 33d) are integrally moved in the optical axis direction or the direction orthogonal to the optical axis has been described, moving the aperture stops (33, 33a to 33d) is not limited to the present invention. Not required. That is,
The aperture stops (33, 33a to 33d) accurately define the light beam diameter on the pupil of the illumination optical system, and the pupil of the illumination optical system is almost accurately determined by the effective diameter of the optical member constituting the illumination optical system. In the case of the aperture stop (33, 33).
This is because the configurations a to 33d) can be omitted.

[0066]

As described above, according to the present invention, even if the fly-eye lens is moved to correct the deviation of the telecentricity, the intensity distribution of the luminous flux incident on the fly-eye lens is invariable. Correction of telecentricity can be performed satisfactorily without impairing the uniformity of the illuminance distribution on the irradiation surface. In addition, since the intensity distribution of the light beam incident on the fly-eye lens is invariable, the displacement of the center of gravity of the light beam can be made almost proportional to the amount of movement of the fly-eye lens. improves.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a configuration of an illumination optical device according to a first embodiment of the present invention.

2A is a perspective view showing the configuration of each lens element 32a constituting the fly-eye lens 32 of FIG. 1, and FIG. 2B is a perspective view showing the incident end face C of the fly-eye lens 32 of FIG.
FIG. 4 is a diagram showing a light intensity distribution in FIG.

FIG. 3 is a diagram schematically showing a configuration of an illumination optical device according to a second embodiment of the present invention.

FIG. 4 is a diagram schematically showing an internal configuration of a spatial image position detecting unit PS in FIG. 1;

FIG. 5 is a view showing an L formed on the surface of a plane parallel plate 100 of FIG. 4;
It is a figure which shows a character-shaped knife edge pattern.

FIG. 6 shows a test pattern T formed on the surface of a substrate W.
It is a figure which shows the intensity distribution along the y direction of the image of P.

FIG. 7 is a diagram illustrating an integrated light amount distribution along the y direction of an image of a test pattern TP obtained by a spatial image position detection unit PS.

FIG. 8 is a diagram showing a signal obtained by differentiating an output signal from the aerial image position detection unit PS.

[Explanation of symbols]

 Reference Signs List 1 light supply system 3 illumination optical system 4 projection optical system 11 light source 12 elliptical mirror 21 light guide 22 multi-branch light guide 31 collimator lens 32 fly-eye lens 33 circular aperture stop 34, 35 condenser lens system R mask RS mask stage W substrate WS Substrate stage PS Spatial image position detector CS1 Control system CS2 Signal processor

Claims (5)

[Claims] 1. A multi-source image forming means for forming a plurality of light source images based on a light beam from a light source, and a light beam from the plurality of light source images formed via the multi-source image forming means. A condenser optical system for illuminating the irradiated surface in a telecentric manner by illuminating, and a relay for conjugating the position of the light source and the positions of the multiple light source images formed via the multiple light source image forming means An optical system, without impairing the uniformity of the illuminance distribution on the irradiated surface,
The light source, the relay optical system, and the multiple light source image forming unit are arranged in an optical axis direction in order to correct a shift in telecentricity caused by non-uniformity of an intensity distribution of a light beam incident on the multiple light source image forming unit. Alternatively, the illumination optical device is capable of integrally moving along a direction perpendicular to the optical axis. 2. A secondary light source forming means for forming a secondary light source based on a light flux from a light source, and a plurality of light sources based on the light flux from the secondary light source formed via the secondary light source forming means. A multi-source image forming means for forming a light source image, and a light source for converging light fluxes from the multiple light source images formed through the multi-source image forming means to illuminate an irradiation surface telecentrically. A condenser optical system, for making the position of the secondary light source formed via the secondary light source forming means and the position of the multiple light source images formed via the multi-light source image forming means conjugate. With a relay optical system, without impairing the uniformity of the illuminance distribution on the irradiated surface,
The secondary light source, the relay optical system, and the multi-source image forming unit are configured to emit light in order to correct a shift in telecentricity caused by non-uniformity of the intensity distribution of the light beam incident on the multi-source image forming unit. An illumination optical device, which is integrally movable along an axial direction or a direction perpendicular to an optical axis. 3. The secondary light source forming means includes: a light guide; and a light source image forming means for forming a light source image at an incident end of the light guide based on a light beam from the light source. The illumination optical device according to claim 2, wherein the secondary light source is formed at an exit end of the light guide. 4. A secondary light source forming means for forming a plurality of secondary light sources based on light fluxes from one or more light sources, and the plurality of secondary light sources formed via the secondary light source forming means. A plurality of light source image forming means for respectively forming a plurality of light source images based on the light flux from each of the secondary light sources; and the plurality of light source images formed via each of the plurality of light source image forming means. A plurality of condenser optical systems for condensing a light beam from the light source image and telecentricly illuminating each area of the irradiated surface, and a plurality of secondary light sources formed via the secondary light source forming means. A plurality of relay optical systems for conjugate each position and the positions of the plurality of light source images formed via each of the plurality of light source image forming means, respectively, Of illuminance distribution in each area Without compromising the uniformity, in order to correct the deviation of the telecentricity caused by the non-uniformity of the intensity distribution of the light beam incident on each light source image forming means, each secondary light source and each relay optical system corresponding to each other An illumination optical device, wherein each of the multiple light source image forming means is integrally movable along an optical axis direction or a direction perpendicular to the optical axis. 5. The secondary light source forming means has the same number of incident ends as the one or more light sources,
A multi-branch light guide having the same number of exit ends as the plurality of multi-light source image forming means; and a light source at each of the entrance ends of the multi-branch light guide based on the light flux from each of the one or more light sources. The image forming apparatus further comprises one or more light sources for forming an image and the same number of light source image forming means, and each secondary light source is formed at each emission end of the multi-branch light guide. The illumination optical device according to claim 4.