DETAILED DESCRIPTION OF THE INVENTION
[0001]
The present invention relates to a method for irradiating a first object with light.
The pattern of the illuminated first object as a second object
Also relates to a projection exposure apparatus for reducing projection onto a substrate or the like.
In particular, the reticle (mask) as the first object
Substrate with circuit pattern formed thereon as second object
Projection exposure equipment suitable for projection exposure on (wafer)
It is about. The present invention also relates to the projection exposure apparatus
The present invention relates to an exposure method using a semiconductor and a semiconductor manufacturing method.
is there. Furthermore, the present invention projects a reticle pattern image onto a substrate.
And a method for adjusting the projection optical system.
[0002]
2. Description of the Related Art In recent years, the pattern of integrated circuits has been increasing.
As the size becomes smaller, the projection used for baking the wafer
The demands on the performance of shadow exposure equipment are becoming more and more severe.
Is coming. Under such circumstances, projection optical system
Has high resolution, flatness of image plane, and low distortion
(Hereinafter, referred to as distortion). So
For these reasons, besides shortening the exposure wavelength λ, the projection optical system
Increase the numerical aperture NA of the lens, reduce the field curvature,
Reduction of curvature has been performed. As such an example
Are disclosed in JP-A-4-157412 and JP-A-5-17306.
No. 5, etc.
Further, a method for adjusting only the magnification error has been proposed.
JP-A-59-144127, JP-A-62-356
There is No. 20. The former has a very thin effect on image performance.
Curved pellicle, such as a pellicle, is placed in the optical path.
It is proposed that the latter is a rotationally symmetric plano-convex lens.
Or a set of rotationally symmetric plano-convex and plano-concave lenses
In the direction of the optical axis to make the overall magnification on the wafer surface isotropic.
It has been proposed to make adjustments dynamically.
[0004]
SUMMARY OF THE INVENTION
JP-A-4-157412 and JP-A-5-173065
The high-performance projection optical system proposed in the patent gazette
The number of constituent lenses is 15 to 24, especially the numerical aperture NA
When it comes to a high-resolution projection optical system of 0.4 or more, the number of components
It is very large, more than 20 sheets. Thus, the request
As the performance becomes more severe, more and more projected light
Academics have become very complicated because of the increasing number of components
I have. Therefore, these projection optical systems were actually manufactured,
Mounted on a projection exposure system to correct field curvature, astigmatism, and distortion
Achieve high performance by keeping aberrations such as differences as designed
The accuracy of individual lens components and assembly accuracy
It must be strictly controlled, so the yield is poor
Or it takes a very long time to manufacture, or
There were problems such as the inability to provide satisfactory performance.
Further, Japanese Patent Application Laid-Open No. 59-144127 proposes
The proposed magnification error correction method uses the image quality of the optical system.
Curve an extremely thin film that does not affect the performance
The magnification error is corrected by the prism action.
Directional asymmetric magnification remaining in the projection optics
Fine adjustment of the error component correction amount and correction direction is not possible.
No. In addition, since the thin film is used,
When the exposure area is elongated as in the projection method, gold
It can be held two-dimensionally by pasting it on a frame, etc.
In the case of a rectangle or square, such a thin film is three-dimensional
It is very difficult to keep
is there. Also, instead of using a thin film to maintain its shape,
Use of a lath etc. does not affect the imaging performance
It is still difficult to make them thin and uniform
In addition, when those films are actually used,
Durability of films etc. including damage accidents due to heat absorption of exposure light
Of optical performance due to heat absorption, heat absorption of exposure light and environmental changes
Very problematic.
In Japanese Patent Application Laid-Open No. 62-35620, the rotation
It is suggested to adjust the magnification error using a symmetric lens
But only by moving the rotationally symmetric lens in the optical axis direction.
Now, only the whole magnification on the wafer surface can be adjusted isotropically
Flaws, directional asymmetric doubles remaining in the projection optics
The rate error component cannot be adjusted.
Further, JP-A-59-144127 and
Magnification error proposed in JP-A-62-35620
In the correction method, only the magnification error can be basically corrected.
Correction for astigmatism as off-axis aberration
Furthermore, it is rotationally asymmetric in the projection optical system and locally
For randomly remaining magnification error components and distortion components
It was also difficult to respond.
[0008] The present invention has been made in view of the above problems.
The accuracy of individual parts and the accuracy of assembly are extremely strict.
Projection light that remains in the projection optics
Optical characteristics that are rotationally asymmetric with respect to the optical axis of the scientific system, such as rotation
Asymmetric off-axis aberration components (astigmatism, field curvature, etc.), rotation
Durable while allowing adjustment of asymmetric magnification error components, etc.
To provide a high-performance projection exposure apparatus with excellent reproducibility and reproducibility.
And the main purpose. In addition, this projection exposure apparatus
Providing an exposure method and a semiconductor manufacturing method using the same.
The purpose is. Also, projection used in a projection exposure apparatus
An object of the present invention is to provide a method for adjusting an optical system. Sa
Are locally rotationally asymmetrical in the projection optical system.
Correction of rotationally asymmetric distortion remaining in the
The secondary purpose is to be able to respond adequately.
[0009]
Means for Solving the Problems To achieve the above object,
For example, the projection exposure apparatus of the first invention illuminates a first object.
Illumination optical system, and the illumination optical system
A projection optical system for projecting an image of the first object onto the second object.
Projection exposure apparatus, the first object and the second object
Rotationally asymmetric astigmatism remaining in the projection optical system between
First optical means for correcting an aberration component;
The rotation non-rotation remaining in the projection optical system with the second object
Second optical means for correcting a symmetric magnification error component,
The first optical unit is configured to detect the rotationally asymmetric magnification error component.
Said rotationally asymmetric astigmatism component with little effect
Is corrected, and the second optical means is provided with the rotationally asymmetric astigmatism.
Rotationally asymmetric magnification error without significantly affecting aberration components
It is characterized in that the difference component is corrected.
The exposure method according to the second invention is characterized in that the first invention
In an exposure method using a bright projection exposure apparatus, the illumination
Illuminating a reticle as the first object using an optical system;
And a pattern of the reticle using the projection optical system.
Projecting an image on a substrate as the second object.
It is characterized by including.
Further, a method of manufacturing a semiconductor according to a third aspect of the present invention includes:
A semiconductor manufacturing method using the projection exposure apparatus of the first invention
In the above, the illumination optical system is used as the first object.
Illuminating the reticle and using the projection optics
A wafer as the second object using a pattern image of the reticle
And projecting the image on the screen.
Further, a method for adjusting a projection optical system according to a fourth aspect of the present invention.
Is a projection optical system that projects the reticle pattern image onto the substrate
In the adjusting method, between the reticle and the substrate
In the projection optical system,
A first step of correcting a difference component, the reticle and the substrate
Rotational asymmetry remaining in the projection optical system between
And a second step of correcting a large magnification error component.
The step has little effect on the rotationally asymmetric magnification error component.
Without affecting the rotationally asymmetric astigmatism component,
The second step is to reduce the rotationally asymmetric astigmatism component.
Corrects rotationally asymmetric magnification error component without affecting
It is characterized by the following.
The projection exposure apparatus according to a fifth aspect of the present invention provides the projection exposure apparatus according to the fourth aspect.
Adjusted by the method for adjusting a projection optical system according to the present invention.
An optical system, and an illumination optical system for illuminating the reticle.
It is characterized by that.
The exposure method according to a sixth aspect of the present invention is the fifth aspect of the invention.
In an exposure method using a bright projection exposure apparatus, the illumination
Illuminating the reticle using an optical system;
Using a shadow optical system, the pattern image of the reticle
And projecting the image on the screen.
Further, a method for manufacturing a semiconductor according to a seventh aspect of the present invention is
A semiconductor manufacturing method using the projection exposure apparatus of the fifth invention
Illuminate the reticle using the illumination optical system.
And a pattern of the reticle using the projection optical system.
Projecting an on-board image onto the substrate.
I do.
[0016]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG.
Is a kind of toric lens with different power
Direction of the cylindrical lens 1 having a refractive power of (y
The focal length in the y 'plane direction) is f1, and the focal length from the cylindrical lens 1 is
The distance to the reticle surface 4 (xy plane) as one object
d11, center position of reticle surface 4 (reticle surface and optical axis A
(the position where x intersects) with the cylindrical lens 1
Is formed between the object point (reticle surface 4) and the cylindrical lens 1.
When the position of an image point (virtual image) to be performed is d12, this cylinder
The Y direction rotated by θ from the y axis of the lens 1 (the optical axis Ax
Imaging magnification β1 in a plane direction including the Y axis) and a cylindrical lens
1 to the image point position d12 (hereinafter simply referred to as the image formation position
Called. ) Is as shown below. Note that FIG.
Although shown, the side opposite to the reticle surface 4 with respect to the cylindrical lens
To project the reticle pattern onto the wafer.
A shadow optical system is arranged, and with reference to FIGS.
It is the same as above.
[0017]
β1 = f1 / (d11 · cos^{Two} θ + f1) (1)
d12 = d11 · f1 / (d11 · cos^{Two} θ + f1) (2)
Similarly, the X direction orthogonal to the Y direction (the optical axis Ax and the X axis
The imaging magnification β1 'and the imaging magnification d12' in
It looks like below.
[0018]
β1 ′ = f1 / (d11 · sin^{Two} θ + f1) (3)
d12 ′ = d11 · f1 / (d11 · sin^{Two} θ + f1) (4)
Therefore, the astigmatism amount AS1 is
AS1 = d12−d12 ′ (5)
Given by
Therefore, if the cylindrical lens 1 is moved,
Since d11 in the expressions (1) to (4) changes, (5)
The amount of astigmatism changes from the equation, and the equation (1) and
It can be understood that the magnification of the equation (3) changes.
On the other hand, if the cylindrical lens 1 is rotated,
Since θ in the equations (1) to (4) changes, the equation (5)
The amount of astigmatism changes, and equations (1) and (3)
It can be seen that the magnification of the equation changes.
Further, as shown in FIG.
Of cylindrical lens 2 with positive refractive power, which is a kind of lens
F2, focal length in the onal direction (yy 'plane direction)
A reticle surface 4 (xy plane) as a first object from the lens 2
D21, the center position of the reticle surface 4 (the
(Where the optical axis Ax intersects with the tickle surface)
The image point position formed by the cylindrical lens 2 is d22.
Is rotated by θ from the y-axis by the cylindrical lens 2
Magnification β in the direction (plane direction including the optical axis Ax and the Y axis)
2 and the distance from the cylindrical lens 2 to the image point position d22 (hereinafter referred to as “d22”).
Below, it is simply called an imaging position. ) Is as shown below.
[0022]
β2 = f2 / (d21 · cos^{Two} θ + f2) (6)
d22 = d21 · f2 / (d21 · cos^{Two} θ + f2) (7)
Similarly, the X direction orthogonal to the Y direction (the optical axis Ax and the X axis
The imaging magnification β2 ′ and the imaging magnification d22 ′ in
It looks like below.
[0023]
β2 ′ = f2 / (d21 · sin^{Two} θ + f2) (8)
d22 ′ = d21 · f2 / (d21 · sin^{Two} θ + f2) (9)
Therefore, the astigmatism amount AS2 is
AS2 = d22−d22 ′ (10)
Given by
Therefore, if the cylindrical lens 2 is moved,
Since d21 in the expressions (6) to (10) changes, (1)
The amount of astigmatism changes from the expression (0), and the expression (6)
It can be seen that the magnification of equation (8) changes.
On the other hand, if the cylindrical lens 2 is rotated,
Since θ in the expressions (6) to (9) changes, the expression (10)
The amount of astigmatism further changes, and equation (6) and
It can be understood that the magnification of the equation (8) changes.
Now, as shown in the above equations (5) and (10),
AS1 and AS2 that have been used are respectively cylindrical lenses (1,
The amount of astigmatism that can be corrected by 2) is obtained.
The best image plane at that time is
(D12 + d12 ') / 2 (11)
(D22 + d22 ') / 2 (12)
The best image plane is given by d11, d21, θ.
Therefore, the amount of curvature of field may also vary.
I understand.
As described above, the imaging magnification, astigmatism,
To adjust the amount and direction for the song, use a cylindrical lens
Move the toric lens in the optical axis direction.
Rotating the toric lens itself such as a cylindrical lens
It is understood that it is good. Note that other than the above adjustment methods
Alternatively, the focal length of the toric lens itself may be changed.
Now, the cylindrical lens 2 shown in FIG. 2 is used.
To estimate the maximum amount of astigmatism correction in cases
If θ = 0, the maximum astigmatism at that time is as follows:
It becomes.
[0030]
AS2_{max} =-(D21)^{Two} / (D21 + f2) (13)
Now, from the reticle as the first object to the c
When the distance to Eha is L, a line of 10 microns or less
Trial printing was performed on the projection exposure equipment that prints the width.
The maximum astigmatism to be corrected
AS2_{max} Is 10^{-Five}L is better than L
Revealed.
Therefore, d21 ≦ 10^{-2}If L, (1
From equation 3),
| F2 | ≧ 10L (14)
And the focal length of the positive cylindrical lens 2 is given by the above equation (14).
It is desirable to satisfy the range.
In addition, two or more as shown in FIGS. 1 and 2
When combining toric lenses such as cylindrical lenses
When combined with another optical element, the reticle 4
Object point by the first toric lens or other optical element
The new image formation position in the direction of interest
From this new object point, the next toric lens
The distance to another optical element is obtained again, and the distance is calculated as d1
What is necessary is just to set it to 1 or d21.
By the way, the negative cylindrical lens shown in FIG.
1 and the positive cylindrical lens 2 shown in FIG. 2 along the optical axis direction.
Consider the case where they are arranged in series.
Now, the generatrix of the two cylindrical lenses (1, 2)
The directions are coincident with each other and the imaging of two cylindrical lenses
If the product of the magnifications is 1, that is, | β1 · β2 | = 1,
The combined power of the two cylindrical lenses (1, 2) in the direction
Nearly zero, magnification and off-axis aberrations (astigmatism, field curvature
Etc.) do not change at all.
On the other hand, the generatrix of the two cylindrical lenses (1, 2)
If the directions are orthogonal to each other, the maximum magnification and maximum
Off-axis aberrations can be generated.
Therefore, the two cylindrical lenses (1, 2) are
Direction that remains in the projection optical system if rotated relatively
Of asymmetric magnification error component and off-axis aberration component
It can be seen that the adjustment for the correction direction can be realized.
The negative cylindrical lens 1 shown in FIG.
When two are arranged in series along the axial direction, or
Two positive cylindrical lenses 2 shown in FIG.
When arranged in rows, the busbar of each cylindrical lens
When the directions match each other, maximum magnification and maximum off-axis
Aberrations can be generated, and each cylinder
When the generatrix directions of the lenses are perpendicular to each other, almost one rotation pair
Can have the same lens action as a nominal spherical lens.
You.
As described above, one type of toric lens is used.
Using at least two cylindrical lenses
By making the cylindrical lens rotatable, the magnification and
The amount of optical characteristics such as off-axis aberrations (astigmatism, field curvature, etc.)
The direction can be adjusted arbitrarily.
In the above, astigmatism and curvature of field are reduced.
We have mainly described the adjustments related to
The negative cylindrical lens 1 shown or the positive cylindrical lens shown in FIG.
Of the magnification error when the lens 2 is rotated about the optical axis Ax.
The adjustment will be described in detail with reference to FIGS.
FIG. 3 shows an arrangement corresponding to the negative cylindrical lens 1 shown in FIG.
A parallel light flux having a radius R centered on the optical axis Ax was made incident.
The state of time is shown. Here, in FIG.
A parallel light flux having a radius R about x is applied to the reticle surface 4 (xy
(A plane) is shown as a circle 13 and the optical axis A
A parallel light flux having a radius R about x is formed by the cylindrical lens 1.
The divergent light beam passes through the virtual plane (x'y 'plane).
The trajectory at the time of passing is shown as an ellipse 11. Also,
FIG. 5 shows light on a virtual plane (x'y 'plane) shown in FIG.
The state of the bundle diameter is shown.
FIG. 4 shows the positive cylindrical lens shown in FIG.
2. A parallel light flux having a radius R centered on the optical axis Ax is incident on 2
This shows the state at the time of being caused. Here, in FIG.
A parallel light flux having a radius R centered on the optical axis Ax forms a reticle surface 4
The trajectory when passing through the (xy plane) is shown as a circle 13,
A parallel light flux having a radius R centered on the optical axis Ax is a cylindrical lens 2
The luminous flux converged by the virtual plane (x'y 'plane)
The ellipse 12 shows the trajectory when passing through
You. FIG. 6 shows a virtual plane (x′y ′ plane) shown in FIG.
2 shows the state of the beam diameter on the surface (1).
The ellipse 11 in FIG. 3 and the ellipse in FIG.
12 is to rotate the cylindrical lenses (1, 2) around the optical axis.
If it rotates with it.
As shown in FIG. 7, the negative cylindrical lens 1
Is a meridional direction on a virtual plane (x'y 'plane)
Beam diameter in y 'direction (plane direction including optical axis Ax and y' axis)
When the amount of change of ΔR1 is ΔR1,
If the distance to the virtual plane (x'y 'plane) is e1,
The relationship is established.
[0044]
ΔR1 = −R · e1 / f1 (15)
Similarly, as shown in FIG.
Y ′ which is a meridional direction on a virtual plane (x′y ′ plane)
Of the beam diameter in the direction (a plane direction including the optical axis Ax and the y 'axis)
Assuming that the change amount is ΔR2, it is more virtual than the positive cylindrical lens 2.
Assuming that the distance to the plane (x'y 'plane) is e2,
The engagement is established.
[0045]
ΔR2 = −R · e2 / f2 (16)
Therefore, as shown in FIGS. 5 and 6, the virtual plane (x ′)
The diameter in the y ′ direction indicated by a solid line on the y ′ plane (the major axis in FIG. 5)
, Half of the minor axis in FIG. 6)
y '= R (1-e1 / f1) (17)
y ′ = R (1−e2 / f2) (18)
And the formula of a circle, that is,
y = ± [R^{Two} + (X ')^{Two} ]^{0.5} (19)
Is converted to xy coordinates by substituting
Ellipses 11 and 12 indicated by solid lines in FIG.
It can be expressed as follows.
[0046]
x^{Two} / R^{Two} + Y^{Two} /[(1-e1/f1).R]^{Two} = 1 (20)
x^{Two} / R^{Two} + Y^{Two} /[(1-e2/f2).R]^{Two} = 1 (21)
Becomes
As described above, for example, FIG.
If there is an asymmetric magnification error as shown in
Rotating the cylindrical lens 1 of FIG.
As a result, the luminous flux diameter as shown in FIG.
Asymmetrical doubling because it can be changed arbitrarily
The rate error can be adjusted. Conversely, inside the projection optical system
Have an asymmetric magnification error as shown in FIG.
In this case, the cylindrical lens of FIG. 4 having the optical characteristics shown in FIG.
By rotating the lens 2, the beam diameter as shown in FIG.
Can be changed arbitrarily from ellipse to circle
Therefore, an asymmetric magnification error can be adjusted.
Here, a negative cylindrical lens 1 as shown in FIG.
Is used, the reticle as the first object is used to
When the distance to the wafer as L is 10 micron
Test exposure equipment that prints line widths
As a result of repeated examinations, the largest magnification error
Is 10^{-Four}(= 100ppm)
The thing turned out.
The focal length f1 of the cylindrical lens 1 and the column
Equation (1) showing the relationship with the magnification β1 of the lens 1 is modified.
Then, the following equation is obtained.
[0050]
f1 = (− d11 · β1) / (β1-1) (23)
Therefore, the maximum magnification error correction amount 10^{-Four}(= 100pp
m) into β1, β1 = 0.9999 (or 1.000
1), and d11 ≦ 10^{-2}If L, then equation (23)
And
| F2 | ≧ 10^{Two} L (24)
And the focal length of the positive cylindrical lens 2 is given by the above equation (24).
It is desirable to satisfy the range.
In the above description, one toric lens
(Cylindrical lens) is rotated around the optical axis direction to magnify
The example of correcting the error has been described, but one toric lens
(Cylindrical lens) in the optical axis direction to compensate for magnification errors.
What can be corrected is the above equations (1), (3), (6) and
It is clear from equation (8). In this case, the above (2)
It is more preferable to satisfy the expression 4).
By the way, in the above description, one story
The magnification error can be corrected using a back lens (cylindrical lens).
Is a kind of toric lens
Using at least two cylindrical lenses, at least one of
Magnification error etc. by making the cylindrical lens rotatable
The amount and direction of the optical characteristics can be arbitrarily adjusted.
Therefore, the negative cylindrical lens 1 shown in FIG.
And the positive cylindrical lens 2 shown in FIG.
Are arranged in series along the
You may let it. In this case, the negative cylindrical lens 1 is shown in FIG.
The positive cylindrical lens 1 has optical characteristics as shown in FIG.
These cylindrical lenses have excellent optical characteristics.
The beam diameter formed by (1, 2) is shown in FIGS.
The beam diameters are synthesized as shown in
The beam diameter can be changed arbitrarily from an ellipse to a circle.
It can be understood that the asymmetric magnification error can be corrected.
Wear.
Further, FIG. 5 or FIG.
When there is an asymmetric magnification error as shown in FIG.
Has at least two or more cylindrical lenses along the optical axis direction.
And at least one of those cylindrical lenses
If one is provided rotatably, as shown in FIG. 5 or FIG.
The luminous flux diameter can be changed arbitrarily from an ellipse to a circle.
Can adjust for asymmetric magnification errors.
You.
Note that two or more toric lenses (columns)
Lens) or other optical elements
In this case, the luminous flux of interest is
Through a cleanse (cylindrical lens) or other optical element
The next toric lens (circle
If you follow it as if it were incident on a column lens)
good.
Two toric lenses (cylindrical lenses)
In combination, the negative cylindrical lens 1 as shown in FIG.
If you install such a positive cylindrical lens in close proximity,
When the generatrix directions of these lenses match, the
The total lens power is almost 0, and the light beam shape changes
But the generatrix directions of each lens are orthogonal
Is the largest shape change.
The negative cylindrical lens 1 shown in FIG.
When two are arranged in series along the axial direction, or
Two positive cylindrical lenses 2 shown in FIG.
When arranged in rows, the busbar of each cylindrical lens
When the directions match each other, maximum magnification and maximum off-axis
Aberrations can be generated, and each cylinder
When the generatrix directions of the lenses are perpendicular to each other, almost one rotation pair
Can have the same lens action as a nominal spherical lens.
You.
As described above, one type of toric lens is used.
Using at least two cylindrical lenses
By making the cylindrical lens rotatable, the magnification and
The amount of optical characteristics such as off-axis aberrations (astigmatism, field curvature, etc.)
The direction can be adjusted arbitrarily.
The above-mentioned equations (14) and (24)
Expressing the formula in a general form is an effective way to correct astigmatism
Let fA be the focal length of the cylindrical lens that can act,
FD is the focal length of the cylindrical lens that can be effectively used for correction.
Then
| FA | ≧ 10L (25)
| FD | ≧ 10^{Two} L (26)
In order to effectively correct astigmatism, the above equation (25) is used.
Should be satisfied, and effectively correct magnification errors
In order to achieve this, it is desirable to satisfy the above expression (26). However
In this case, the focal length of the cylindrical lens (fA, fD)
Is not limited to a single cylindrical lens,
Combines toric lenses and toric reflective members
It can be applied even if it is done. In other words, this cylindrical lens
Focal lengths (fA, fD) have multiple toric optical components
Focal length of multiple cylindrical lenses in the case of combining
Separated.
From the relation of the equation (25) or (26),
When the toric component is too strong,
The effect on the difference comes out and becomes a problem. For example, correction of astigmatism
In this case, the field curvature and magnification error become worse,
In the correction, the telecentricity and the astigmatism deteriorate. This
Therefore, within the above range, effectively correct asymmetric aberration
Can be done.
By the way, in the above equations (25) and (26),
Indicates the optimal focal length range for toric optics.
However, from the other point of view,
Consider the range of focal length.
First, FIG. 9 shows that the projection optical system has an aperture stop S
The reticle 4 side is the front group GF, and the wafer 5 side is the rear group G
R, where the front group GF is f_{GF}
The rear group GR has a focal length of f_{GR}Have a focal length of
The projection optical system is telescopic on the reticle side and on the wafer 5 side.
It is centric.
FIG. 10 shows the front group G of the projection optical system shown in FIG.
Between F and reticle 4 as a toric optical member
Shows how a cylindrical lens with positive power is placed
The power of the cylindrical lens 2 is in the direction of the paper of FIG.
(Meridional direction).
Here, as shown in FIG.
Is the focal length of f2 between the cylindrical lens 2 and the front group GF.
(The distance between the principal points of both optical systems) is D_{1} To be
And the combined focal length F of the cylindrical lens 2 and the front group GF_{1} Is
The following relationship is established.
[0065]
F_{1} = (F2 · f_{GF}) / (F2 + f_{GF}-D_{1} ) (27)
Also, the imaging magnification B of the projection optical system (GF, GR)_{1} age,
A composite system of the cylindrical lens 2 and the projection optical system (GF, GR)
Imaging magnification B_{1}Then, the following relationship is established.
[0066]
B_{1} = -F_{GR}/ F_{GF} (28)
B_{1}'= -F_{GR}/ F_{1} = B_{1} [1+ (f_{GF}-D_{1} ) / F2] (29)
Therefore, the sagittal direction and the meridional direction of the projection optical system
Magnification difference ΔB at_{1} Is as follows.
[0067]
ΔB_{1} = B_{1}'-B_{1} = B_{1} (F_{GF}-D_{1} ) / F2 (30)
On the other hand, the reticle by the composite system of the cylindrical lens 2 and the front group GF
H_{1} System composed of the cylindrical lens 2 and the front group GF
The focal position on the reticle side by P_{1} , Its focal position P
_{1} Δs to the distance to the reticle 4_{1} , With the cylindrical lens 2
Of the reticle 4 by the combination system with the shadow optical system (GF, GR)
Image formation position Q_{1} Δs from the wafer to the wafer 5_{1}'
And the following relationship is established.
[0068]
Δs_{1} = (F_{GF}-D_{1} )^{Two} / (F2 + f_{GF}-D_{1} ) (31)
Δs_{1}'= (B_{1}')^{Two} ・ Δs_{1} (32)
Where Δs_{1}'Is the sagittal direction of the projection optical system and Meridio
The difference in the imaging position in the null direction, that is, the amount of astigmatism (astigmatism)
(Difference).
The numerical aperture on the reticle side of the projection optical system is
NA_{R} If the wavelength of the exposure light is λ, the projection optical system
DOF on the vehicle side_{R} Is as follows.
[0070]
DOF_{R} = Λ / (NA_{R} )^{Two} (33)
Therefore, the amount of astigmatism is determined by focusing on the reticle side of the projection optical system.
In order to keep the depth within the range, the above equation (31) and (3)
From equation (3), the following equation is derived.
[0071]
f2 ≧ − (f_{GF}-D_{1} ) + [(NA_{R} )^{Two}(F_{GF}-D_{1} )^{Two} ] / Λ (34
)
Therefore, the cylindrical lens 2 is configured so as to satisfy the expression (34).
To focus on the amount of astigmatism.
It is possible to keep it within the depth.
If this expression (34) is generally expressed,
Power difference in the direction orthogonal to the optical member is Δf
Then, it becomes as follows.
Δf ≧ | − (f_{GF}-D_{1} ) + [(NA_{R} )^{Two}(F_{GF}-D_{1} )^{Two} ] / Λ | (35
)
Thus, when a toric optical member is used,
Focus on the reticle side of the projection optical system
In order to keep the depth within the range, the above equation (35) must be satisfied.
It is understood that is preferred. Note that the above equation (34) and
The relationship between (35) and (35) is that the projection optical system is
Needless to say, this is true even when the magnification is large.
No.
As an example, open the reticle side of the projection optical system.
NA_{R} 0.1, the wavelength of the exposure light λ is 436 nm,
f_{GF}= 250mm, f_{GR}= 250mm, D_{1} = 200m
Assuming m, from the above equation (34), the merging of the cylindrical lens
The focal length f2 in the onal direction, generally speaking (3)
From equation (5), the toric optical member in the direction orthogonal to
The power difference Δf is 5.7 × 10^{Four} mm
Magnification change amount (magnification difference ΔB_{1} ) Is 87
0 ppm (= 8.7 × 10^{-Four})
In the above description, toric type optics
Before placing the member between the reticle and the projection optical system
Equation (35) was derived as a suggestion.
The same applies when the member is placed between the projection optical system and the wafer.
In this case, the following relationship is established.
It is desirable to be satisfied.
[0075]
Δf ≧ | − (f_{GR}-D_{1}') + [(NA_{W} )^{Two}(F_{GR}-D_{1}')^{Two} ] / Λ | (3
6)
However, NA_{W} Is the numerical aperture on the wafer side of the projection optical system,
D_{1}'Is the distance between the toric optical member and the rear group GR
(Distance between principal points of both optical systems).
Next, the projection optical system will be described with reference to FIG.
Between the front group GF and the rear group GR in the middle, in other words, the aperture stop
When a positive cylindrical lens 2 is placed near S
The optimum focal length range of lens 2 will be considered. FIG.
Is a distance between the front group GF and the rear group GR of the projection optical system shown in FIG.
Cylinder with positive power as a toric optical member
This figure shows the state when the lens 2 is arranged.
The power of lens 2 is in the direction of the paper of FIG. 11 (meridional
Direction).
Here, as shown in FIG.
Is the focal length of f2 between the front group GF and the cylindrical lens 2.
(The distance between the principal points of both optical systems) is D_{Two} To be
And the combined focal length F of the front group GF and the cylindrical lens 2_{Two} Is
The following relationship is established.
[0078]
F_{Two} = (F2 · f_{GF}) / (F2 + f_{GF}-D_{Two} ) (37)
Also, the imaging magnification B of the projection optical system (GF, GR)_{Two} age,
A composite system of the cylindrical lens 2 and the projection optical system (GF, GR)
Imaging magnification B_{Two}Then, the following relationship is established.
[0079]
B_{Two} = -F_{GR}/ F_{GF} (38)
B_{Two}'= -F_{GR}/ F_{Two} = B_{Two} [1+ (f_{GF}-D_{Two} ) / F2] (39)
Therefore, the sagittal direction and the meridional direction of the projection optical system
Magnification difference ΔB at_{Two} Is as follows.
[0080]
ΔB_{Two} = B_{Two}'-B_{Two} = B_{Two} (F_{GF}-D_{Two} ) / F2 (40)
On the other hand, the retic by the combined system of the front group GF and the cylindrical lens 2
H_{Two} , Composite system of front group GF and cylindrical lens 2
The focal position on the reticle side by P_{Two} , Its focal position P
_{Two} Δs to the distance to the reticle 4_{Two} , Projection optical system (GF
, GR) and a cylindrical lens 2 in a combined system.
Imaging position Q_{Two} Δs from the wafer to the wafer 5_{Two} 'To
Then, the following relationship is established.
[0081]
Δs_{Two} = (F_{GF})^{Two} / (F2 + f_{GF}-D_{Two} ) (41)
Δs_{Two}'= (B_{Two}')^{Two} ・ Δs_{Two} (42)
Where Δs_{Two}'Is the sagittal direction of the projection optical system and Meridio
The difference in the imaging position in the null direction, that is, the amount of astigmatism (astigmatism)
(Difference).
Accordingly, the amount of astigmatism is determined by the reticle of the projection optical system.
(33)
The following formula is derived from the formula and the formula (41).
[0083]
f2 ≧ − (f_{GF}-D_{Two} ) + [(NA_{R} )^{Two}(F_{GF})^{Two} ] / Λ (43)
Therefore, the cylindrical lens 2 is configured so as to satisfy the expression (43).
To focus on the amount of astigmatism.
It is possible to keep it within the depth.
If this expression (43) is generally expressed,
Power difference in the direction orthogonal to the optical member is Δf
Then, it becomes as follows.
[0085]
Δf ≧ | − (f_{GF}-D_{Two} ) + [(NA_{R} )^{Two}(F_{GF})^{Two} ] / Λ | (44)
Thus, when a toric optical member is used,
Focus on the reticle side of the projection optical system
In order to keep the depth within the range, the above equation (44) must be satisfied.
It is understood that is preferred. Note that the above equation (43) and
The relationship between (44) and (44) is that the projection optical system is
Needless to say, this is true even when the magnification is large.
No.
As an example, open the reticle side of the projection optical system.
NA_{R} 0.1, the wavelength of the exposure light λ is 436 nm,
f_{GF}= 250mm, f_{GR}= 250mm, D_{Two} = 200m
Assuming that m, from the above equation (43), the merging of the cylindrical lens
The focal length f2 in the onal direction, generally speaking (4)
From equation 4), the toric type optical member in the direction orthogonal to
The power difference Δf is 1.43 × 10^{6} mm or more
Magnification correction amount (magnification difference ΔB_{1} ) Is 3
5 ppm (= 3.5 × 10^{-Five})
From the results of the analysis shown in FIGS.
Between reticle and projection optics or between projection optics and wafer
If a toric optical member is placed between
Magnification error while minimizing the contribution of correction to astigmatism
Can increase the contribution of correction to
On the other hand, toric light is placed on or near the pupil of the projection optical system.
When disposing mechanical components, correction of magnification error
Increase the contribution of correction to astigmatism while keeping the
It can be understood that it is possible to make it easier.
The toric optical member referred to in the present invention and
Is polished in one direction of a rotationally symmetric spherical surface,
With different power in different directions
Or have different powers in orthogonal directions
It may be a reflecting mirror, or it may have different power in orthogonal directions.
A refractive index distribution type lens having a refractive index may be used.
By the way, the description so far is based on the projection optical system.
As an aspheric surface that is rotationally asymmetric with respect to the optical axis of
Using toric optics with different power in different directions
Rotationally asymmetric astigmatism, field curvature, magnification error, etc.
Has been described, but rotationally asymmetric
In addition to these aberrations and magnification errors,
Rotationally asymmetric and locally random magnification error component
Or distortion components occur along the optical axis direction.
Toric optics that can be moved or rotated about the optical axis
Local polishing on the lens surface of a cylindrical lens as one type of member
Polishing, etc., and process the cylindrical lens
Rotationally asymmetric when placed between tickle and wafer
Astigmatism, curvature of field, and magnification errors,
Corrects magnification error components and distortion components that occur randomly.
It is possible to
Further, the projection optical system is rotationally asymmetric and locally
Only the magnification error component and distortion component that remain at random
In the case of having an optical element,
(Lens, reflecting mirror) itself is subjected to local processing such as polishing
For example, the magnification error component and distortion component
Correction is also possible.
The projection optical system is rotationally asymmetric and locally
Only the magnification error component and distortion component remaining at random
If there is, a magnification error that occurs randomly
Component with a certain thickness to correct the components and distortion components.
Process, such as polishing, locally on the two parallel flat plates
Between the reticle and the projection optical system.
Arranged inside the projection optics or between the projection optics and the wafer
May be placed. However, in this case, the plane parallel plate has a predetermined thickness.
Has spherical aberration, but the spherical
What is necessary is to configure the projection optical system in advance so that aberrations can be corrected.
No.
Next, an embodiment of the present invention will be described with reference to FIG.
Will be described in detail. FIG. 12 shows an embodiment of the present invention.
1 shows a configuration of a projection exposure apparatus according to an embodiment. As shown in FIG.
As such, both sides (or one side) telecentric projection lens
Above the lens 36, a reticle stage (not shown)
The reticle 35 is arranged, and the reticle 35 and the projection lens
Between the projection lens 36 and the optical axis of the projection lens 36.
Orthogonal direction as optical means with rotationally asymmetric power
Toric type optical members with different powers
Have been. This toric type optical member is
Turn the concave surface toward the projection lens side in the
Negative cylindrical lens 1 with a convex surface facing the reticle side
Positive cylindrical lens 2 with positive power in the paper direction
The cylindrical lens 1 and the cylindrical lens 2 are
Each is provided rotatable about the optical axis.
Further, with respect to the projection lens 36, the reticle 3
5 is placed on a wafer stage 37 at a position conjugate with
The wafer stage 3
Reference numeral 7 denotes an XY stage and a projection lens that can move two-dimensionally.
Composed of a Z stage movable in the optical axis direction
ing.
On the other hand, above the reticle 35, a reticle
An illumination optical system (2
1, 22, 23, 24, 25, 32, 33, 34)
The optical characteristics of the projection lens are included in the illumination optical system.
And a measurement system 42 for measuring the
Are different between the reticle 35 and the wafer 38 by light of different wavelengths.
First alignment system for optically detecting relative position of
47 are provided respectively.
Further, there is an off-axis outside the projection lens 36.
An axis-type second alignment system 48 is provided.
The second alignment system 48 is provided with an exposure light I to be described later.
The position of the wafer 38 is optically adjusted by light having a wavelength different from L.
Detection.
The embodiment shown in FIG. 12 will be specifically described.
Then, the exposure light IL radiated from the light source 21 such as a mercury lamp
Is collected by the elliptical mirror 22 and reflected by the reflection mirror 23.
After being reflected by the collimator lens 24,
Optics converted to line luminous flux and composed of fly-eye lenses
The light enters the cal integrator 25. Second of the elliptical mirror 22
A shutter 26 is disposed near the focal point.
-26 through a drive unit 27 such as a motor.
Thus, the exposure light IL can be blocked at any time.
The shutter 26 blocks the exposure light IL.
The exposure light I reflected by the shutter 26
L is emitted in a direction substantially perpendicular to the optical axis of the elliptical mirror 22.
The exposure light IL emitted in this manner is incident on the condenser lens 28.
More light is incident on one end of the light guide 29. Therefore, light
The exposure light IL emitted from the source 21 is an optical
Incident on either the Greater 25 or the Light Guide 29
You.
Exposure light to the optical integrator 25
When the IL enters, the optical integrator 25
A number of secondary light source images (hereinafter simply referred to as
It is called a secondary light source. ) Is formed, and the secondary light source forming surface is formed.
The variable aperture stop 30 is disposed. Those secondary light sources
Exposure light IL emitted from is tilted by 45 degrees with respect to the optical axis.
After passing through the arranged half mirror 31, the first core
Condenser lens 32, dichroic mirror 33 and
The lower surface of the reticle 35 via the second condenser lens 34
The pattern area on the side is illuminated with uniform illuminance.
At the time of exposure, the toric optical member (1,
2) and the pattern of the reticle 35 by the projection lens 36
Is formed on the wafer 38. In this case,
The secondary light source forming surface of the cal integrator 25 is a projection lens
36 is conjugate with the pupil plane, and is arranged on the secondary light source forming plane.
By adjusting the aperture of the variable aperture stop 30
The coherency of the illumination optical system that illuminates the ticicle 35 is shown.
Σ value can be changed. Illuminates reticle 35
The maximum incident angle of the exposure light IL_{IL}Of the projection lens 36
The half angle of the opening on the_{PL}Then the σ value is sin
θ_{IL}/ Sinθ_{ } _{PL}Can be represented by Where the σ value is
It is set to about 0.3 to 0.7.
The pupil position of the projection lens 36 is not shown.
However, an aperture stop is provided.
The mouth may be configured to be variable. Also, wafers
In the vicinity of the wafer holder of the stage 37, for example, a glass plate
The adjustment plate 39 is fixedly provided.
A reference pattern is formed on the surface of the
ing. Correspondingly, the image lens of the projection lens 36 is
In the field and near the pattern area of the reticle 35
Is the reference pattern on the adjustment plate 39 and the projection lens 36.
Reticle mark RM is formed at a conjugate position with respect to
I have. As an example, the reference pattern on the adjustment plate 39 side is light-shielded.
It consists of a cross-shaped opening pattern formed in the
The reticle mark RM on the Eha 35 side is
Toric optical members (1, 2) and projection lens 36
Inverts the brightness of the pattern obtained by multiplying
It consists of a pattern obtained by
On the lower surface of the adjustment plate 39 of the wafer stage 37
Indicates that the condenser lens 41 and the reflection mirror 40 are arranged.
Light condenser on the rear focal plane of the condenser lens 41.
The exit end of the gate 29 is fixed. This light guide 2
9 is conjugate with the pupil plane of the projection lens 36.
It is also conjugate with the variable aperture stop 30. Also, this light guy
The light emitting surface of the exit end of the aperture 29 is projected onto the variable aperture stop 30.
The size of the image is set approximately equal to the aperture of the variable aperture stop 30.
Therefore, the reference pattern on the adjustment plate 39 is
Illumination with an illumination σ value approximately equal to the illumination σ value for the exposure light IL
It is. Further, in the illumination optical system of the exposure light IL,
Position conjugate with the variable aperture stop 30 with respect to the
The light receiving section of the photomultiplier 42 is
You. That is, the light receiving portion of the photomultiplier 42 is projected.
Both the pupil plane of the lens 36 and the exit end face of the light guide 29
It is arranged to be useful. Detection surface of the light receiving section
Is the emission end of the light guide 39 projected on it.
It is larger than the image on the light surface to prevent light loss. Obedience
Thus, the reference pattern of the adjustment plate 39 was illuminated from the lower surface side.
In this case, the adjustment plate 39 is
Reference pattern of the adjustment plate 39 regardless of the position
Most of the light emitted from the projector
Incident on the optical member (1, 2),
After the tickle mark RM, the photomultiplier 42
Light enters the light receiving surface.
The central processing unit 43 (hereinafter referred to as CPU)
I do. ) Is electrically connected to the photomultiplier 42.
From the photomultiplier 42.
The input photoelectric conversion signal is supplied to the CPU 43. Ma
In addition, an X-direction mirror and
A Y-direction mirror (not shown) is fixed, and the laser interference system 44 is fixed.
And the use of these two mirrors,
It is possible to constantly monitor the coordinates of the position on the stage 37.
Wear. The laser interference system 44 sends the CPU 43
The coordinate information from the eha stage 37 is supplied, and the CPU 4
Reference numeral 3 denotes a wafer stage 3 via a stage driving unit 45.
7 can be moved to the desired coordinate position.
You.
Next, the operation of this embodiment will be described.
explain. The projection lens 36 and
Optics remaining in the optical members (1, 2)
Optical characteristics that are rotationally asymmetric with respect to the optical axis of the system (astigmatism, image
To measure surface curvature, magnification error, and distortion).
And a reticle stage (not shown) as shown in FIG.
A reference reticle 35 'is previously arranged. This reference
In the pattern area of the tickle 35 ', as shown in FIG.
Cross-shaped light-shielding pattern such as chrome is two-dimensionally
They are arranged at intervals.
[0104] The CPU 43
After the exposure light IL is blocked by the
Projecting adjustment plate 39 on wafer stage 37 through 45
The lens 36 is moved into the image field. this
As a result, the exposure light IL (hereinafter referred to as the
Below, it is simply called illumination light. ) Is the condenser lens 28 and
Into the wafer stage 37 via the guide 29
Is done. After this illumination light is reflected by the reflection mirror 40,
Is converted into a substantially parallel light beam by the condenser lens 41.
The reference pattern formed on the adjustment plate 39 from the lower side.
Light up. The reference pattern of the adjustment plate 39 is
And the toric optical member (1, 2)
The light is projected onto the light-shielding pattern of the quasi-reticle 35 '.
The matching state of the two patterns is determined by the second capacitor
34, dichroic mirror 33, first condensate
A photo camera is provided through the sur lens 33 and the half mirror 31.
It is detected photoelectrically by the multiplier 42. And
The CPU 43 is arranged two-dimensionally in the reference reticle 35 '.
The coordinates of the positions of the plurality of shaded patterns
In order to detect sequentially through the prior 42, the laser
The coordinate position of the wafer stage 37 is always set via the negotiation system 44
While monitoring, the wafer is
The stage 37 is sequentially moved. With this, the photo
The multiplier 42 is two-dimensional within the reference reticle 35 '.
Of a plurality of light-shielding patterns arranged in parallel and the reference of the adjusting plate 39
Each of the matching states with the pattern is photoelectrically detected, and CP
U43 indicates the coordinate position of each matching state by laser drying.
To the first memory unit inside the CPU 43 via the communication system 44
And store them sequentially. Further, not shown inside the CPU 43.
A second memory unit and a first correction amount calculating unit;
The second memory section is rotated about the optical axis of the projection optical system.
Asymmetric optical characteristics (astigmatism, field curvature, magnification error, distortion
Curvature) and the relative relationship between the toric optical members (1, 2).
Information related to the rotation amount is stored in advance.
Therefore, the first correction amount calculating unit includes the first and second memory units.
From the toric optical member (1,
The optimum relative rotation amount to be corrected in 2) is calculated. So
Then, based on the correction information from the first correction amount calculating unit,
The CPU 43 outputs a drive signal to a drive unit 46 such as a motor.
Then, the drive unit 46 controls the torque by a predetermined correction amount (rotation amount).
The optical members (1, 2) are relatively rotated.
After the above operation is completed, the actual process
The ordinary reticle 35 used for
CPU 43 shuts down via drive unit 27
Switch 26. As a result, the exposure light IL is irradiated.
The reticle 35 is illuminated through the bright optical system,
The pattern image of No. 5 is a toric optical member (1, 2) and
Faithfully transferred onto the wafer 38 via the projection lens 36
You. In this manner, the exposure transfer by the projection exposure apparatus is continuously performed.
Then, the thermal energy by the exposure light IL is
Energy is stored, and the optical characteristics of the projection lens 36 fluctuate.
Periodically during the exposure transfer operation.
In addition, as described above, the optical characteristics of the projection lens 36 are used.
The toric type based on the measured results.
What is necessary is just to rotate the optical member (1, 2). At this time, projection
By controlling the pressure between the lenses constituting the lens 36, the
The well-known technique of adjusting the magnification of the shadow lens 36 itself and
It is more desirable to use them together.
The toric optical member (1, 2)
The rotation remaining in the projection lens 36 depends on the relative rotation amount.
Asymmetric optical characteristics (astigmatism, field curvature, magnification error,
Distortion has been corrected in a fully optimized state
It is desirable to confirm that
By repeating the above operation, more complete correction can be achieved.
In addition, the magnification error remaining in the projection lens 36
When measuring the difference and the distortion, the wafer stage 37 is
Each light-shielding path in the reference reticle 35 'is moved two-dimensionally.
It is sufficient to find the coordinate position of the turn.
When measuring astigmatism and field curvature remaining in the object more accurately
The wafer stage 37 in the optical axis direction of the projection lens 36.
While moving from the photomultiplier 42
Reference reticle that maximizes the contrast of the output signal
It is sufficient to find the coordinate position of each light shielding pattern in the frame 35 '.
No.
The projection exposure apparatus according to the present embodiment
Non-linear expansion and contraction of the wafer 38 due to the conductor manufacturing process, etc.
When manufacturing semiconductors with multiple projection exposure devices
When magnification errors and distortion differences occur between projection exposure devices
Can be fully supported. Specifically, first,
The CPU 43 includes a plurality of wafers formed on the wafer.
The coordinate position of the mark is provided outside the projection lens 36.
Optically sequentially detected through the second alignment 48
The wafer stays through the laser interference system 44
While constantly monitoring the coordinate position of the
The wafer stage 37 is sequentially moved via the moving part 45
You. Thereby, the CPU 43 sets the second alignment 48
And formed on the wafer obtained from the laser interference system 44
The coordinate position of each wafer mark is stored in a third
Store them sequentially in the memory unit. Further, the inside of the CPU 43
Has a fourth memory unit and a second correction amount calculating unit (not shown).
The optical axis of the projection optical system is stored in the fourth memory unit.
Rotationally asymmetric optical properties (astigmatism, field curvature,
Magnification error, distortion) and toric optical member (1,
Information related to the relative rotation amount of 2) is stored in advance.
Has been delivered. Therefore, the second correction amount calculation unit calculates the third and
Based on the information from the fourth memory unit, the toric light
The optimal relative rotation amount of the structural member (1, 2) to be corrected
calculate. Then, the correction information from the correction amount calculation unit is
The CPU 43 outputs a drive signal to the drive unit 46 such as a motor based on the
And the drive unit 46 triggers by a predetermined correction amount (rotation amount).
The relative optical elements (1, 2) are relatively rotated.
In the embodiment shown in FIG.
Rick type optical member (1, 2)
The rotationally asymmetric optical characteristics (astigmatism) remaining in the projection lens 36
Aberration, curvature of field, magnification error, distortion)
As described above, the toric optical members (1, 2) are relatively
Note that the projection lens 36 may be moved in the optical axis direction.
Needless to say. In the embodiment shown in FIG.
Rotationally asymmetric optical characteristics (astigmatism, image
Example of automatic correction of surface curvature, magnification error, distortion)
However, the rotation or transfer of the toric optical member (1, 2)
The movement can be performed manually.
The light source 21 and the elliptical mirror in this embodiment
A collimated light beam is provided instead of the collimator lens 22 and the collimator lens 24.
A laser light source such as an excimer laser to be supplied may be used,
In addition, this laser and this laser beam
Combined with a beam expander that converts to surface light
Is also good. By the way, in the embodiment shown in FIG.
Between the projection lens and the toric optical member (1,
Although the example where 2) was arranged was described, it is not limited to this arrangement.
Alternatively, the configuration shown in FIG.
FIG. 14A shows the projection lens 36 and the wafer.
A toric optical member (1, 2) is arranged between the optical member (38) and (c).
An example is shown. As shown, toric optical section
The materials (1, 2) are sequentially placed on the reticle 35 from the wafer 38 side.
The negative cylindrical lens 1 with the concave surface facing the side and the wafer 38 side
A positive cylindrical lens 2 having a convex surface. This structure
According to the embodiment, astigmatism is similar to the embodiment shown in FIG.
With little effect on the correction of magnification error
Can greatly contribute. Therefore, the projection lens
When a large magnification error remains within 36
It is valid (similar to the embodiment shown in FIG. 12).
FIG. 14B shows the front group 36A and the rear group 36A.
B, the front lens 36A and the rear
Between the group 36B, that is, the pupil position of the projection lens 36 or
A toric optical member (1, 2) is arranged in the vicinity.
An example is shown. As shown, toric optical member
(1, 2) are on the wafer 38 side in order from the reticle 35 side.
Cylindrical lens 1 with the concave surface facing the reticle 35 side
A positive cylindrical lens 2 having a convex surface. This structure
According to the result, without significantly affecting the magnification error,
Can greatly contribute to astigmatism correction
You. Therefore, a large amount of astigmatism remains in the projection lens 36.
It is effective when it exists.
FIG. 14C shows a state where the projection lens 36 is interposed.
To the reticle 35 and wafer 38, respectively.
FIG. 2 shows an example in which the optical members (2A, 2B) are arranged.
You. As shown, between the reticle 35 and the projection lens 36
A first positive cylindrical lens having a convex surface facing the wafer 38 side.
A projection lens 36 and a wafer 38
A second positive circle having a convex surface facing the reticle 35 side.
A column lens 2B is provided. According to this configuration,
12 and as in the example shown in FIG.
With little effect on the correction of magnification error
It can greatly contribute.
FIG. 14D further shows FIG. 14C.
This shows an example of application, in which a projection lens 36 is sandwiched between
Positively arranged on the wafer 35 side and the wafer 38 side, respectively.
Each of the cylindrical lenses (2A, 2B) has a negative cylindrical lens (1
A, 1B) are shown. In this configuration
According to the report, magnification has little effect on astigmatism.
This can greatly contribute to error correction. This
In the case of, the first toric optical member (1A, 2A)
One of the second toric optical members (1B, 2B)
Mainly compensates for the magnification error remaining in the projection lens 36.
Correction, magnification error for expansion and contraction of wafer 38 by the other
May be corrected. Furthermore, based on this configuration
And the first toric optical member (1A, 2A) and the second
One of the toric optical members (1B, 2B)
By configuring the power to be strong and the other weak,
The toric optical member with higher power
Rough adjustment of magnification error can be performed without significantly affecting
On the other hand, the toric type optical member with weak power has
Fine adjustment of the magnification error is performed without significantly affecting the difference.
I can.
(E) of FIG. 14 is equivalent to (a) of FIG.
An example of further application in combination with (b)
As shown, the reticle 35 and the projection lens (front group 36)
A), between the negative cylindrical lens 1A and the positive cylindrical lens
2A and a first toric optical member (1
A, 2A) are provided and the projection lens 36
Between the front group 36A and the rear group 36B (the pupil of the projection lens 36).
Position or its vicinity), the negative cylindrical lens 1B and the positive
Second toric light composed of the cylindrical lens 2B of FIG.
A learning member (1B, 2B) is provided. With this configuration
Then, in the first toric optical member (1A, 2A),
Adjustment of magnification error without significantly affecting astigmatism
With the second toric optical member (1B, 2B)
Adjusts astigmatism without significantly affecting magnification error.
Correction, that is, the magnification error and the astigmatism are independently compensated.
Can be corrected.
(F) of FIG. 14 corresponds to (d) of FIG.
(E) is shown in combination with magnification error and
In addition to independent correction of astigmatism, magnification error and astigmatism
Can be roughly adjusted and finely adjusted.
[0117]
According to the present invention, projection light due to manufacturing errors
Prevent degradation in academic performance and ensure high-performance
It is possible to obtain shadow optics, and in production,
Leads to improvement. Also, actively use these features
Without affecting the projection optics.
Process expansion and contraction caused by non-linear
By correcting the rotationally symmetric magnification error between the units,
A decrease in matching accuracy can be prevented. Also, some source
Astigmatism and distortion caused by the optical system itself
Can be corrected.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a principle diagram when a toric lens is a negative cylindrical lens. FIG. 2 is a principle diagram when a toric lens is a positive cylindrical lens. FIG. 3 is a diagram illustrating the operation of the negative cylindrical lens of FIG. 1; FIG. 4 is a view showing the operation of the positive cylindrical lens of FIG. 2; FIG. 5 is a plan view showing a state of a light beam cross section on a virtual plane shown in FIG. 3; 6 is a plan view showing a state of a light beam cross section on a virtual plane shown in FIG. 4; FIG. 7 is a diagram showing a geometric optical relationship of the negative cylindrical lens shown in FIG. 3; FIG. 8 is a diagram showing a geometric optical relationship of the positive cylindrical lens shown in FIG. FIG. 9 is a diagram illustrating a geometric optical relationship of the projection optical system. 10 is a diagram showing a geometric optical relationship when a cylindrical lens as a toric lens is arranged between the projection optical system shown in FIG. 9 and a reticle. 11 is a diagram showing a geometric optical relationship when a cylindrical lens as a toric lens is arranged near the pupil of the projection optical system shown in FIG. FIG. 12 is a diagram showing a configuration of an example according to the present invention. FIG. 13 is a plan view showing a state of a reference reticle. 14A is a diagram illustrating a state where a positive cylindrical lens and a negative cylindrical lens as a toric lens are arranged between a reticle and a projection lens, and FIG. 14B is a diagram illustrating a pupil position of the projection lens or FIG. 3C shows a state in which a positive cylindrical lens and a negative cylindrical lens as a toric lens are arranged in the vicinity of the toric lens. FIG. 4C shows a toric lens between the reticle and the projection lens and between the projection lens and the wafer. FIG. 3D shows a state in which a positive cylindrical lens as a lens is disposed. FIG. 4D shows a positive cylindrical lens as a toric lens and a negative lens between the reticle and the projection lens and between the projection lens and the wafer. A diagram showing a state when a cylindrical lens is arranged,
(E) is a diagram showing a state where a positive cylindrical lens and a negative cylindrical lens as a toric lens are disposed between the reticle and the projection lens and at or near the pupil position of the projection lens, respectively, and (f). Shows a state in which a positive cylindrical lens and a negative cylindrical lens as a toric lens are arranged between the reticle and the projection lens, and at or near the pupil position of the projection lens, and between the projection lens and the wafer, respectively. FIG. [Description of Signs] 1 ... Negative cylindrical lens, 2 ... Positive cylindrical lens, 21 ... Light source, 22 ... Elliptical mirror, 23 ... Reflection mirror, 24 ... Collimator lens, 25 ... Optical integrator, 32 ...
1st condenser lens, 34 ... second condenser lens, 36 ... projection lens, 37 ... wafer stage, 38
... wafer, 42 ... photomultiplier, 48 ... second
Alignment system.
Continuation of front page (56) References JP-A-7-183190 (JP, A) JP-A-59-144127 (JP, A) JP-A-62-21118 (JP, A) JP-A-5-21319 (JP) JP-A-4-134813 (JP, A) JP-A-3-88317 (JP, A) (58) Fields investigated (Int. Cl. ^{7} , DB name) H01L 21/027 G02B 13/24 G03F 7/20