JP2000283889A - Inspection device and method of projection optical system, aligner, and manufacture of micro device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve an inspection device and method for excluding the influence of vibration with a low frequency when inspecting a projection optical system without using any expensive anti-vibration device, an aligner for accurate exposure, and further a method for manufacturing a micro device for improving a product yield. SOLUTION: A test pattern formed on a test reticle Rt is projected onto a light reception surface 42 of an image pickup mechanism 41 via a projection optical system PLe to be inspected. The light reception time of a projection image on the light reception surface 42 is changed for each aberration to be measured. In this case, when the aberration to be obtained based on the contrast of the projection image is to be measured, the said light reception time is set to approximately 1/2 cycle of vibration with the minimum frequency out of vibrations operating on an inspection device body 22. Also, when the aberration to be obtained based on the coordinates positions of the said projection image is to be measured, the said light reception time is set to approximately 1 cycle of the vibration with the said minimum frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure device used in a photolithography process in a manufacturing process of a micro device such as a semiconductor device, a liquid crystal display device, a thin film magnetic head, an image sensor, a reticle, a photo mask and the like. The present invention relates to an apparatus, an inspection apparatus and an inspection method for a projection optical system used for an exposure apparatus, and a method for manufacturing the microdevice.

[0002]

2. Description of the Related Art As an exposure apparatus of this type, for example, the following is known. That is, a predetermined illumination light is applied to a circuit pattern formed on a mask such as a reticle or a photomask, and an image of the circuit pattern is projected and transferred onto a substrate such as a wafer or a glass plate via a projection optical system. Here, if aberration is present in the projection optical system,
The projected image of the circuit pattern formed via the projection optical system becomes distorted, and the yield of the product substrate may be reduced. For this reason, the aberration of the projection optical system is measured using various inspection methods and inspection devices.

In particular, in a semiconductor device manufactured by transferring a circuit pattern formed on a reticle onto a wafer, a large number of different circuit patterns have been formed with each other due to a remarkable increase in the degree of integration in recent years. The layers are overlaid in layers in a state where they are aligned with each other. For this reason, in order to secure the overlay accuracy, more strict measurement of the aberration of the projection optical system is required.

As a method for inspecting the projection optical system, for example, the following method is known. That is, the projected image of the inspection pattern formed on the inspection mask is converted into a conjugate plane (image plane) of the inspection projection optical system via the inspection projection optical system.
Is formed on an image pickup mechanism arranged such that a light receiving surface is located at a position corresponding to the light receiving surface. Then, a projection image of the pattern is captured by the imaging mechanism, and the captured projection image is subjected to image processing, thereby inspecting the aberration of the projection optical system. Note that the imaging mechanism is an XYZ three-axis moving stage (hereinafter, referred to as a moving stage) whose moving amount can be measured by a laser interferometer or the like.
It is called "XYZ stage". ) Is placed on top.

Items causing distortion of the projected image of the projection optical system include so-called “Seidel's five aberrations” (spherical aberration, coma, astigmatism, field curvature, distortion). In the inspection of these aberrations, as the inspection pattern, a line and space (hereinafter, referred to as “L·L”) in which a plurality of linear marks are repeatedly arranged at predetermined intervals.
S ". ) Dark line pattern or bright line pattern. In addition, a large number of the LS patterns are formed on the inspection mask at a predetermined distance.

Inspection of the spherical aberration, coma aberration, astigmatism, and curvature of field among the above-mentioned five aberrations is performed by comparing the contrast of light and dark in the projected image of the LS pattern captured by the imaging mechanism. Required based on. In order to maximize this contrast, it is necessary to find the best focus position that serves as a measurement reference. The best focus position is detected by sequentially moving the light receiving surface of the imaging mechanism along the optical axis of the projection optical system to change the focus position of the projection optical system, and sequentially capturing the projection image. Then, the contrast of the projected image at each of the focus positions is measured, and the best focus position is obtained by calculating a contrast = focus curve.

On the other hand, the distortion is obtained based on the coordinate position of the projected image of each of the LS patterns within the projection range of the projection optical system to be inspected. The coordinate position is obtained based on the position of the center of gravity of each projection image and the value read by the length measuring device.

The inspection of the projection optical system as described above is performed in a state where the projection optical system to be inspected is mounted on an exposure apparatus having the projection optical system or a dedicated inspection apparatus. Further, in order to ensure a highly accurate exposure operation in the exposure apparatus, it is necessary to strictly inspect the projection optical system, that is, measure each of the aberrations.

Here, the exposure apparatus and the inspection apparatus include:
In order to reduce the influence of vibration transmitted from the outside to those devices, a vibration isolator is provided. This is because if vibrations are transmitted to the exposure apparatus and the inspection apparatus during the capture of the projection image, the projection image that should be still may swing. When the projection image fluctuates in this way, the time required for capturing the projection image by the imaging mechanism is very short, so that the contrast may decrease or the projection image itself may move in parallel. Then, there is a possibility that the contrast and the coordinate position of the projected image cannot be measured accurately.

As this kind of vibration isolator, there is known, for example, a vibration isolator which is interposed between the exposure apparatus and the inspection apparatus and a floor on which the apparatus is installed. The anti-vibration table includes a plurality of legs for accommodating a buffer member therein, and a mounting plate on which the exposure device and the inspection device are mounted. The mounting board is connected to the buffer member via a connecting member, and the exposure apparatus and the inspection apparatus are mounted in a floating state from the installation floor. As the buffer member, a coil spring that is evenly displaced by a load is used. Such an anti-vibration table is a so-called passive anti-vibration table that removes vibration using only the natural frequency of the coil spring.

Further, the exposure apparatus and the inspection apparatus eliminate the environmental dependence of the dimensions of each member constituting the apparatus, and
In order to accurately measure the coordinate position of the projection image, it is usually installed in a constant temperature room.

[0012]

In the passive vibration isolating table having the above-mentioned structure, vibrations having a relatively high frequency of, for example, 50 Hz or more can be effectively eliminated. However, in an environment surrounding the exposure apparatus and the inspection apparatus, the frequency is lower than the frequency (for example, 23 Hz or 48 Hz).
(Frequency of the order of magnitude) is generated from, for example, air conditioning equipment in a constant temperature room. In addition, the same low-frequency vibration as described above may be generated from a crane used when transporting the exposure apparatus and the inspection apparatus or when replacing the projection optical system in the inspection apparatus. Further, in general, the floor of the building where the exposure apparatus and the inspection apparatus are arranged is often designed to have a natural frequency of about 10 Hz for anti-earthquake measures and the like.

As described above, in the environment surrounding the exposure apparatus and the inspection apparatus, simple vibrations of various frequencies are simultaneously generated. Then, when these simple vibrations are overlapped, a lower frequency combined vibration having a beat frequency close to the natural frequency of the coil spring is generated.
It is difficult to sufficiently remove such low-frequency simple vibrations and composite vibrations using only a conventional passive vibration isolation table. Then, when the two vibrations are transmitted to the exposure device and the inspection device, there is a problem that the measurement accuracy of the contrast of the projected image and the coordinate position may not be sufficiently secured.

In order to completely eliminate both low frequency vibrations, for example, the following method can be considered. That is, a vibration sensor is attached to the exposure apparatus and the inspection apparatus, and the vibration transmitted to those apparatuses is detected. And
A so-called active anti-vibration table having a function of generating vibration in a phase opposite to the transmitted vibration based on the detection result of the vibration sensor and canceling the transmitted vibration is employed.

However, the adoption of the active anti-vibration table for positively applying the vibration of the opposite phase as described above is very expensive in itself, and causes a significant increase in the manufacturing cost of the exposure apparatus and the inspection apparatus. Is generated. In addition, the vibration isolation table and its peripheral configuration become large, which causes a problem that the configuration of the exposure apparatus and the inspection apparatus becomes complicated and large.

Moreover, such an active vibration isolation table is
The structure is completely different from that of the passive anti-vibration table employed in the conventional exposure apparatus and inspection apparatus.
Therefore, it is not easy to additionally provide the active vibration isolation table or replace the passive vibration isolation table with the active vibration isolation table in the conventional exposure apparatus and inspection apparatus.

The present invention has been made by paying attention to such problems existing in the prior art. An object of the present invention is to provide an inspection apparatus and an inspection method for a projection optical system that can eliminate the influence of low-frequency vibration when inspecting the aberration of the projection optical system without using an expensive anti-vibration apparatus. Another object is to provide an exposure apparatus capable of accurately measuring aberration of a projection optical system and performing accurate exposure. Still another object is to provide a method for manufacturing a micro device capable of improving the yield of products.

[0018]

In order to achieve the above object, the invention according to the first aspect of the present invention, which relates to an inspection apparatus for a projection optical system, uses an inspection pattern (PA1 to PA4, PB1, PB1, P2).
B2) an illumination optical system (32) for illuminating the inspection mask (Rt), and the inspection patterns (PA1 to PA).
4, PB1, PB2) onto a predetermined surface (42, 87), and a projection optical system (PLe, PL);
2,87) projected onto the inspection pattern (PA1
ＰＡPA4, PB1, PB2) based on the projected images, measuring means (53) for measuring the imaging characteristics of the projection optical system (PLe, PL), and an inspection device (53) for the projection optical system (PLe, PL). 21, 61), wherein the measuring means (53)
The predetermined surface (42) according to at least one of the type of imaging characteristics of the projection optical system (PLe, PL) to be measured in and the characteristic of vibration acting on the inspection device (21, 61). , 87) is provided with control means (52) for changing the projection time of the projection image projected onto the projection image.

Here, as a result of various studies, the present inventor has determined whether the imaging characteristic of the object to be measured is measured based on the contrast of the projected image of the inspection pattern, or is measured based on the coordinate position. It was found that the contrast and the period of the change of the coordinate position differed depending on the object. According to the first aspect of the present invention, the projection time of the projection image is changed according to at least one of the type of the imaging characteristic to be measured and the characteristic of the vibration acting on the inspection device. It has become. Therefore, the projected image can be formed in the best state for each type of the image forming characteristics and for each characteristic of the acting vibration. Thus, the influence of the low-frequency vibration can be eliminated without using an expensive anti-vibration device, and the imaging characteristics of the projection optical system can be accurately measured based on the projection image.

According to a second aspect of the present invention, in the first aspect of the present invention, a detecting means (63) for detecting the characteristic of the vibration is further provided.

Therefore, according to the second aspect of the present invention, in addition to the operation of the first aspect, the characteristic of the vibration actually acting on the inspection apparatus is detected by the detection means. be able to. By setting the projection time of the projection image according to the characteristics of the vibration, the imaging characteristics of the projection optical system can be measured more accurately.

According to a third aspect of the present invention, in the first or the second aspect of the present invention, a light receiving surface (42, 8) for receiving the projection image is provided on the predetermined surface.
7) is arranged.

Therefore, according to the third aspect of the present invention, in addition to the operation of the first or second aspect, the projection optical system can be used in accordance with the state of use of the projection optical system. The measurement of the imaging state can be performed.

According to a fourth aspect of the present invention, in accordance with the third aspect of the present invention, the control means (52)
Is characterized in that a light receiving time on the light receiving surface (42, 87) is changed as the projection time.

For this reason, according to the invention described in claim 4 of the present application, the light receiving time of the projected image is determined for each imaging characteristic of the measurement object in accordance with the period of the contrast and the coordinate position variation in the projected image of the inspection pattern. Can be adjusted. This makes it possible to average the variation in the contrast of the projection image and the parallel movement of the projection image itself, which are the basis of the measurement of each imaging characteristic by the measurement unit.

In the invention described in claim 4 of the present application,
In addition to the effect of the invention according to the third aspect, with a simple configuration in which the light receiving time of the projected image of the inspection pattern is simply changed, the influence of low-frequency vibration when measuring the imaging characteristics of the projection optical system is obtained. Can be eliminated.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the light amount of the light beam incident on the light receiving surface (42, 87) is reduced. A light quantity changing means (43, 33) for changing is further provided.

When the projected image of the inspection pattern is captured using an image sensor (CCD) prior to the measurement of the imaging characteristics by the measuring means, the CCD is saturated depending on the accumulation time of the projected image. It may be in a state. On the other hand, in the invention described in claim 5 of the present application, in addition to the effect of the invention described in any one of claims 1 to 4, the light is projected onto the light receiving surface by the light amount changing unit. The light quantity of the projected image can be adjusted. For this reason,
As described above, the saturation of the CCD can be avoided, and the imaging characteristics of the projection optical system can be accurately measured.

The invention according to claim 6 of the present invention, which relates to a method for inspecting a projection optical system, uses an inspection pattern (PA1 to PA4, PB1, PB1) formed on an inspection mask (Rt).
2) through a projection optical system (PLe, PL) to a predetermined surface (4).
2,87) and the inspection patterns (PA1 to PA1)
Measuring means (53) for measuring the imaging characteristics of the projection optical system (PLe, PL) based on the projected images of PA4, PB1, PB2)
In the method of inspecting the projection optical system (PLe, PL), the type of the imaging characteristic of the projection optical system (PLe, PL) to be measured by the measurement means (53) and the inspection pattern ( PA1 to PA4, PB1, PB2)
Changing the projection time of the projection image projected on the predetermined surface (42, 87) in accordance with at least one of the characteristics of vibration acting when projecting the image on the predetermined surface (42, 87). It is characterized by the following.

Therefore, the invention according to claim 6 of the present application exerts substantially the same operation as the invention according to claim 1. The invention according to claim 7 of the present invention relates to an exposure apparatus (71) for transferring a pattern formed on a mask (R) onto a substrate (W) via a projection optical system (PL). A projection optical system inspection apparatus according to any one of claims 1 to 5, and a correction for correcting an imaging characteristic of the projection optical system (PL) based on an inspection result of the inspection apparatus. Means (89, 92, 93).

Therefore, according to the present invention, the imaging characteristics of the projection optical system can be accurately measured without using an expensive anti-vibration device, and an accurate exposure operation is ensured. be able to. And the yield in the product substrate can be improved.

Further, in the invention according to claim 8 of the present invention relating to a method for manufacturing a micro device, a device pattern formed on a mask (R) is transferred onto a substrate (W) via a projection optical system (PL). Then, in the method of manufacturing a micro device for forming a predetermined circuit pattern on the substrate (W), the type of imaging characteristics of the projection optical system (PL) to be measured and the inspection mask (Rt) The inspection pattern (PA1 to PA4, PB1, PB2) is projected onto the predetermined surface (42, 87) via the projection optical system (PL) according to at least one of the following: By changing the projection time of the projection image of the inspection pattern (PA1 to PA4, PB1, PB2) projected on the predetermined surface (42, 87), the inspection pattern (PA1 to PA4) is changed.
, PB1, PB2) on the predetermined surface (42, 87), and based on the projection image after the change of the projection time, measures the imaging characteristics of the projection optical system (PL). The imaging characteristic of the projection optical system (PL) is corrected on the basis of this, and the device pattern on the mask (R) is transferred onto the substrate (W).

Therefore, according to the present invention, the imaging characteristic of the projection optical system can be accurately measured without using an expensive anti-vibration device, and based on the measurement result, it is possible to accurately measure the image forming characteristic. The imaging characteristics of the projection optical system can be corrected. As a result, the circuit pattern on the mask is accurately transferred onto the substrate, so that the yield on the product substrate can be improved.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment in which an inspection apparatus and an inspection method for a projection optical system according to the present invention are embodied in a dedicated inspection apparatus will be described with reference to FIGS. Will be explained.

FIG. 1 is an external view in which a part of the inspection apparatus is cut away, and FIG. 2 is a schematic view of the inspection apparatus of FIG. As shown in FIGS. 1 and 2, the inspection device 21 includes an inspection device main body 22 and a vibration isolation table 23. On the base 24 of the inspection apparatus main body 22, a lower frame 25 for detachably holding the test projection optical system PLe is provided upright. On the base 24, an XYZ stage 26 and a laser interferometer (hereinafter, referred to as "length measuring device") 27 are arranged. The XYZ stage 26 can be moved in three XYZ directions by a stage driving unit 28. A pair of movable mirrors 29 are erected on the XYZ stage 26 along the X and Y directions. The length measuring device 27 is arranged to face the movable mirror 29. The length measuring device 27 emits a predetermined laser beam to the movable mirror 29,
Based on the interference between the emitted light and the reflected light from the movable mirror 29, the position of the XYZ stage 26 in the XY biaxial directions is measured.

In this case, the projection optical system PL
The direction along the optical axis AX of e is the Z axis, the direction orthogonal to the optical axis AX and along the plane of FIG. 2 is the X axis, and the direction orthogonal to the optical axis AX and the plane of FIG. 2 is the Y axis. I do.
FIGS. 1 and 2 show only the length measuring device 27 and the movable mirror 29 that measure the position of the XYZ stage 26 in the X direction.

An upper frame 30 is erected on the lower frame 25. A reticle holder 31 is mounted on the upper gantry 30 above the projection optical system PLe to be inspected, and a test reticle Rt as an inspection mask is held on the reticle holder 31 by vacuum suction. The test reticle Rt is held such that its center is located on the optical axis AX of the projection optical system PLe.

The test reticle R is placed on the upper pedestal 30 above the test reticle Rt.
illumination optical system 32 for illuminating t with predetermined illumination light IL
Is arranged. The illumination optical system 32 includes a light source 33,
Fly-eye lens 34, relay lens 35, mirror 3
6, the condenser lens 37 and the like.

The light source 33 serves as the illumination light IL,
For example, pulsed light such as KrF excimer laser light, ArF excimer laser light, and F2 excimer laser light is emitted.
The fly-eye lens 34 is composed of a number of lens elements, and a number of secondary light source images corresponding to the respective lens elements are formed on the exit surface. Then, the secondary light source image is transferred to the relay lens 35 and the mirror 3
6. The test reticle Rt is superimposed on the test reticle Rt via the combining system of the condenser lens 37,
The upper part is illuminated with a uniform illuminance distribution.

A shutter mechanism 39 having a shutter 38 is attached to the lower surface of the illumination optical system 32. The shutter 38 is moved back and forth with respect to the optical path of the illumination light IL by a shutter driving unit 40, and the test reticle Rt
The irradiation of the illumination light IL upward is interrupted.

An image pickup mechanism 41 including an image pickup device (CCD) is arranged on the XYZ stage 26. By driving the XYZ stage 26, the imaging mechanism 41 is moved in the XYZ three-axis directions in the projectable range of the test projection optical system PLe.

Between the light receiving surface 42 of the image pickup mechanism 41 and the test projection optical system PLe, a dimming plate 43 as a light amount changing means is interposed. The neutral density plate 43 has a disk shape, and a plurality of neutral density filters 44 having different transmittances with respect to the illumination light IL are arranged at equal angular intervals in the circumferential direction. Then, by rotating the dimming plate 43 by the dimming plate driving unit 45, each of the dimming filters 44
Correspond to the light receiving surface 42 of the imaging mechanism 41. Then, the neutral density filters 4 having different transmittances are used.
By selecting 4, the intensity of the illumination light IL incident on the light receiving surface 42 is adjusted.

The anti-vibration table 23 is connected to the inspection apparatus main body 22.
Is mounted, and hollow cylindrical legs 47 are arranged at four corners of the mounting board 46. Inside each leg 47, a coil spring 48 having a predetermined spring constant is accommodated. This coil spring 4
The mounting board 46 is connected to an upper portion of the base 8 via a connecting member 49. Then, with the exposure apparatus main body 22 floating above the floor FL of the installation location,
Is placed on top. Here, the vibration isolation table 23 is a so-called passive vibration isolation table that removes vibrations using only the natural frequency of the coil spring 48.

Next, a configuration for measuring the imaging characteristics of the projection optical system PLe will be described. As shown in FIGS. 3 and 4, when measuring the imaging characteristics, a plurality of test patterns PA1 to P
A test reticle Rt in which A4, PB1 and PB2 are formed is used. These one set of test patterns PA1 to P
A4, PB1, and PB2 constitute a test pattern group PG. On the test reticle Rt, a plurality of test pattern groups PG are formed at predetermined intervals with a two-dimensional spread. In the present embodiment, the pattern area PR on the test reticle Rt corresponding to the projectable range of the test projection optical system PLe
Within, the center, the four corners, the middle of the four corners,
And a total of 13 intermediate image heights between the center and the four corners.
The test pattern group PG is formed at several locations.

The test patterns PA1 to PA4, PB
1, PB2 includes a plurality of linear light shielding portions Ps in the light transmitting portion Pt.
Are L / S dark line patterns arranged and formed at predetermined intervals. The test patterns PA1 to PA4 differ from PB1 and PB2 in the arrangement cycle (line width) of the light-shielding portions Ps. In addition, the test patterns PA1, PA2, PA3, and PA4 are different from each other, and the test patterns PB1 and PB2 are different in the arrangement direction of the light shielding portions Ps.

Now, as shown in FIG. 2, the stage driving unit 28 for driving the XYZ stage 26 and the illumination light I
The light source 33 that emits light L, the shutter driving unit 40 that drives the shutter 38, and the dimming plate driving unit 45 that drives the dimming plate 43 are all connected to a main control system 52 that controls the operation of the entire inspection apparatus main body 22. Have been. That is, the X
The YZ stage 26, the light source 33, the shutter 38, and the dimming plate 43 are operated based on a command from the main control system 52.

The length measuring device 27 is connected via the main control system 52 to an arithmetic processing unit 54 provided in an aberration detecting unit 53 as measuring means. Then, information on the position of the XYZ stage 26 in the XY directions is output from the length measuring device 27 to the arithmetic processing unit 54 via the main control system 52. The stage drive system 28
Is connected to the arithmetic processing unit 54 via the main control system 52. Then, information on the position of the XYZ stage 26 in the Z direction is output from the stage drive system 28 to the arithmetic processing unit 54 via the main control system 52.

The imaging mechanism 41 is connected to the arithmetic processing section 54 via a frame memory 55 provided in the aberration detection section 53. Then, information on the image received by the imaging mechanism 41 via the light receiving surface 42 is temporarily stored in the frame memory 55 and then input to the arithmetic processing unit 54. The frame memory 55
Is connected to a monitor 56 for checking the light receiving state of the projected image of the pattern on the test reticle Rt in the imaging mechanism 41.

In the arithmetic processing section 54, the image pickup mechanism 4
The imaging characteristics of the projection optical system PLe are measured based on the information on the received light image input from step 1 and the information on the position of the XYZ stage 26 input from the length measuring device 27 and the stage drive system 28. Is done.

The main control system 52 stores information on the opening time of the shutter 38 for each type of the imaging characteristics to be measured, and the transmittance of the neutral density filter 44 changed for each opening time. Is connected. The main control system 52 includes a timer 58.
Is equipped. The main control system 52 is provided with a selection switch according to the type of the imaging characteristic to be measured, and according to the imaging characteristic selected by the selection switch, the opening time of the shutter 38, The configuration may be such that the information on the transmittance is called from the storage device 57.

Next, the operation of measuring the imaging characteristics of the projection optical system PLe will be described. The main control system 52 instructs the stage driving unit 28 to move the XYZ stage 26 to a predetermined position. Thereby, the imaging mechanism 41
Of the test patterns PA1 to PA projected on the light receiving surface 42 of the test projection optical system PLe within a projectable range of the test projection optical system PLe.
4, PB1 and PB2.

Next, the main control system 52 stores the information necessary for the measurement (the opening time of the shutter 38, the light-
4 etc.). And the main control system 52
Optimal dimming filter 44 for the dimming plate driving unit 45
On the light receiving surface 42. The main control system 52 sets the opening time of the shutter 38 in the timer 58. Next, the main control system 52 instructs the light source 33 to emit the illumination light IL.

Then, the main control system 52 instructs the shutter drive section 40 to open the shutter 38, and at the same time when the shutter 38 is opened, the timer 58 starts counting time. Thereby, the test patterns PA1 to P1
The projected images of A4, PB1 and PB2 are projected projection optical systems PL.
The light is projected onto the light receiving surface 42 of the image pickup mechanism 41 via e. Then, the projection image is captured and accumulated by the imaging mechanism 41. When the time set by the timer 58 elapses, the main control system 52 instructs the shutter drive unit 40 to close the shutter 38 and instructs the light source 33 to stop emitting the illumination light IL. . Thus, the capturing of the projection image in the imaging mechanism 41 is stopped.

Information on the image of the projection image taken into the image pickup mechanism 41 is temporarily stored in the frame memory 55. At the same time, information on the position of the XYZ stage 26, that is, the position of the light receiving surface 42, is input to the arithmetic processing unit 54 from the length measuring device 27 and the stage driving unit 28. Then, in the arithmetic processing unit 54, based on the information, the test projection optical system PL
The imaging characteristic of e is measured.

The above-mentioned imaging characteristics, that is, "Seidel's five aberrations" are roughly classified into the following two. One is aberration in the optical axis direction obtained based on contrast of light and dark in the projection image captured by the imaging mechanism 41.
The aberration in the optical axis direction includes spherical aberration, coma, astigmatism, and field curvature. The other is aberration in the direction orthogonal to the optical axis, which is obtained based on the coordinate position in the projection image. The aberration in the orthogonal direction includes distortion.

The case of measuring the aberration in the optical axis direction will be described, including the method of measuring the best focus position. First, in order to measure the best focus position, the XYZ stage 26 is stepwise moved at predetermined intervals along the optical axis AX of the projection optical system PLe by the stage drive unit 28. Thereby, the imaging mechanism 41
Is moved stepwise to change the focus position of the projection optical system PLe. Then, at each of the focus positions, test patterns PA1 to PA4, PB1, PB2 for each of the imaging characteristics to be measured.
Is appropriately selected to detect the projected image.

Here, it is assumed that, for example, a test pattern PA1 as shown in FIG. In this case, the theoretical light intensity distribution at the best focus position of the projected image is as shown in FIG. However, actually, even when the light passes through the test projection optical system PLe in an ideal state, the waveform of the light intensity distribution obtained from the binarized image based on the shading of the projected image is as shown in FIG. It becomes like c). Then, the waveform of the light intensity distribution is determined by the focus position, the test projection optical system PL.
It changes subtly due to the aberration remaining in e.

The arithmetic processing unit 54 calculates, for each focus position, the amplitude of the main peak MP in the waveform of the intensity distribution of the light that has passed through the light transmitting part Pt of the test pattern PA1 thus obtained. Then, the contrast for each focus position is detected from the amplitude of the main peak MP at each focus position. From the detection result, a relationship curve between the focus position and the contrast is calculated, and the focus position having the highest contrast is determined as the best focus position.

When measuring the spherical aberration, the test patterns having different line widths from each other, for example, PA1 and PB1
Or, using PA2 and PB2, the best focus position of the projected image of each test pattern PA1 and PB1 or of the projected image of PA2 and PB2 is obtained. The spherical aberration is obtained by measuring the difference between the best focus positions.

When measuring the coma aberration, at least one of the test patterns PA1 to PA4 in the test pattern group PG arranged at the four corners of the pattern region PR on the test reticle Rt or at an intermediate portion between them. Use Then, the test patterns PA1 to PA4
Then, an intensity difference (peak height difference) ΔI between a pair of pseudo peaks SP1 and SP2 generated at both ends of the main peak MP of the light intensity distribution waveform of the projection image at the best focus position is measured.

If no coma aberration exists in the projection optical system PLe, as shown in FIG.
No difference occurs between the intensities of the pair of pseudo peaks SP1 and SP2. On the other hand, when the test projection optical system PLe has a coma aberration, as shown in FIG.
An intensity difference ΔI corresponding to the amount of coma is generated between the pair of pseudo peaks SP1 and SP2. As a result, the measured intensity difference ΔI between the pseudo peaks SP1 and SP2 is determined by the previously calculated pseudo peak SP in each coma aberration amount.
The coma in the arrangement direction of the test patterns PA1 to PA4 used for the measurement is obtained by collating with the relational expression of the intensity difference ΔI between SP1 and SP2.

In determining the astigmatism, the test patterns PA1 to PA4 in four different directions are used. Here, the best focus position on the sagittal plane is obtained using the test pattern PA1, and the best focus position on the tangential plane is obtained using the test pattern PA2. Further, the best focus position in the 45 ° direction is obtained using the test pattern PA3, and the best focus position in the 135 ° direction is obtained using the test pattern PA4. Then, by measuring the difference between the best focus position on the sagittal surface and the tangential surface, and the difference between the best focus position in the 45 ° direction and the 135 ° direction,
Astigmatism is required.

When determining the field curvature, the astigmatism measurement is performed for a plurality of test pattern groups PG including a test pattern group PG arranged at the center of the pattern area PR on the test reticle Rt. Do. Then, the best focus position of the projected image of each test pattern PA1 to PA4 of the pattern group PG arranged in the peripheral portion with respect to the best focus position of the projected image of each test pattern PA1 to PA4 of the pattern group PG arranged in the central portion. By measuring the deviation, the curvature of field is obtained.

On the other hand, when measuring the aberration in the orthogonal direction, that is, the distortion, first, the stage driving section 28 moves the XYZ stage 26.
Thereby, at least one projected image of the test patterns PA1 to PA4 in the test pattern group PGc located at the center of the test reticle Rt shown in FIG. The projected image is captured by the imaging mechanism 4.
1 and stored in the frame memory 55, the arithmetic processing unit 54 calculates the position of the center of gravity of the projected image from the waveform of the light intensity distribution in the projected image. The length measuring device 27 is reset to zero using the position of the center of gravity as the position of the center coordinates.

Next, the XYZ stage 26 is
By moving in the biaxial direction, a plurality of other test pattern groups P different from the test pattern group PGc located at the central portion
For at least one of the test patterns PA1 to PA4 in G, similar detection of the position of the center of gravity of the projected image is sequentially performed. At this time, the main control system 52 instructs the length measuring device 27 to measure the position of the XYZ stage 26 in the XY biaxial directions in synchronization with the capturing of the projection image by the imaging mechanism 41. The measurement result is input to the arithmetic processing unit 54. Accordingly, the center of gravity of the projected image of the test patterns PA1 to PA4 in each of the test pattern groups PG is set to the coordinate with the origin being the center of gravity of the test patterns PA1 to PA4 in the test pattern group PGc arranged at the center. It is obtained as a coordinate position on the system. Then, in the arithmetic processing unit 54, the coordinate position of each of the projection images and the lattice points in the ideal lattice, that is, the test projection optical system PLe
Is calculated by measuring the difference from the coordinate position of each projected image when it is assumed that no distortion exists.

According to the results of intensive studies by the inventor of the present invention, it has been found that in the measurement of the contrast of the projected image, the contrast varies for each measurement mainly due to the influence of a low frequency simple vibration. . Further, in the measurement of the coordinate position of the projected image, it has been found that the entire projected image moves in parallel in the XY plane mainly due to the influence of a further low-frequency synthesized vibration generated by superimposing a plurality of the simple vibrations. Was.

Here, as shown in FIG. 6, in the conventional configuration, the light receiving time of the projected image in the image pickup mechanism 41 is very short with respect to the cycle of the lowest frequency vibration of the combined vibration. is there. In contrast, the imaging mechanism 4
By extending the light receiving time of the projection image in No. 1, the variation in the contrast and the translation of the coordinate position could be greatly reduced. This is because the swing motion of the projected image due to the low frequency vibration is averaged within the light receiving time of the projected image.

In order to most effectively suppress the variation in the contrast, the light receiving time is set to a time substantially corresponding to or exceeding a half cycle of the lowest frequency vibration. In this case, if the light receiving time becomes extremely long, the contrast is reduced as a whole. For this reason, the light receiving time is preferably in the range of 1/4 to 3/4 cycle of the lowest frequency vibration, and more preferably in the range of 1/3 to 2/3 cycle.

In order to most effectively suppress the parallel movement of the coordinate position, the light receiving time should be set to a time that substantially corresponds to one cycle of the lowest frequency vibration of the combined vibration or that exceeds the period. , Preferably in the range of 2/3 to 4/3 cycle of the lowest frequency vibration, more preferably 3/4.
Set within the range of ５/4 cycle.

Therefore, the first structure configured as described above
According to the embodiment, the following effects can be obtained. (A) In the inspection device 21 of the first embodiment, the main control system 52 determines the test pattern PA in the imaging mechanism 41 according to the aberration of the projection optical system PLe to be measured.
The light receiving times of the projected images 1 to PA4, PB1 and PB2 are changed. Here, aberrations in the optical axis direction (spherical aberrations, measured based on the contrast of the projection image)
(Coma aberration, astigmatism, curvature of field), the light receiving time is set so as to be approximately 周期 cycle or more of the lowest frequency vibration among the synthetic vibrations affecting the measurement. In the orthogonal aberration (distortion) measured based on the coordinate position of the projection image, the light receiving time is set so as to be substantially equal to or more than one cycle of the lowest frequency vibration among the synthetic vibrations affecting the measurement. Is set.

For this reason, when the projected image is received by the image pickup mechanism 41, the variation in the contrast of each measurement and the parallel movement of the projected image caused by the fluctuation of the projected image are averaged. Accordingly, the projected image at the time of measuring each aberration can always be formed in the best state, and the influence of the low-frequency vibration can be eliminated without using an expensive so-called active vibration isolation table.

Therefore, each aberration present in the projection optical system PLe to be measured can be accurately measured based on the projection image. In addition, it is possible to prevent the manufacturing cost of the inspection device 21 from increasing remarkably and the vibration damping table 23 and its peripheral configuration to be complicated and large.

In addition, the test patterns PA1 to PA
4, the influence of low frequency vibration can be eliminated with a simple configuration such as changing the light receiving time of the projected images of PB1 and PB2. Therefore, it is possible to realize the inspection apparatus 21 capable of accurately inspecting the projection optical system PLe without increasing the number of components and complicating the configuration.

(B) Inspection apparatus 21 of the first embodiment
In the figure, the light receiving surface 42 of the imaging mechanism 41 that receives the projected images of the test patterns PA1 to PA4, PB1, and PB2 is arranged on the image plane of the test projection optical system PLe. For this reason, it is possible to easily and accurately measure each aberration present in the test projection optical system PLe in accordance with the use state of the test projection optical system PLe.

(C) Inspection apparatus 21 of the first embodiment
In this embodiment, a dimming plate 43 for changing the amount of light in the projected images of the test patterns PA1 to PA4, PB1 and PB2 incident on the light receiving surface 42 of the imaging mechanism 41 is provided.

In the first embodiment, the projection image is captured by a CCD provided in the imaging mechanism 41. In this case, according to the length of the accumulation time of the projection image,
By adjusting the light quantity of the projection image passing therethrough by the dimming plate 43, the light quantity of the projection image reaching the CCD can be adjusted. Therefore, the CCD can be prevented from becoming saturated, and the imaging characteristics of the projection optical system can be accurately measured.

(Second Embodiment) In an inspection apparatus 61 according to a second embodiment, as shown in FIGS. 7 and 8, the shutter mechanism 39 and the dimming plate 43 in the inspection apparatus main body 62 are used.
Is different from that of the first embodiment. The inspection device main body 62 has a vibration sensor 6 on its base 24.
3, and an enlargement optical system 65 is provided in the imaging mechanism 64.

In the inspection device main body 62, the shutter mechanism 39 is disposed on the XYZ stage 26 so as to cover the light receiving surface 42 of the image sensor 64 in an openable and closable manner. Further, the dimming plate 43 is provided with the illumination optical system 32.
Provided between the fly-eye lens 34 and the relay lens 35.

The vibration sensor 63 is connected to the base 2
4, which detects the period of the vibration acting on the base 24 and outputs information on the period of the vibration to the main control system 52.

Further, the magnifying optical system 65 is disposed below the light receiving surface 42 of the imaging mechanism 64,
2, the test patterns PA1 to PA4, PB
1 and PB2 are enlarged to a predetermined magnification. The projection image magnified by the magnifying optical system 65 is taken in by an imaging device (CCD) 67 via a mirror 66.

In the inspection apparatus 61 of the second embodiment, when measuring the imaging characteristics of the projection optical system PLe to be inspected, the main control system 52 adds to the type of the imaging characteristics to be measured. A light receiving surface 4 of the imaging mechanism 64 based on information on the cycle of the vibration input from the vibration sensor 63;
2, the light receiving time is set. In other words, at the time of measuring the imaging characteristics, the main control system 52 determines the optimal shutter mechanism 39 according to the period of the vibration actually acting on the inspection apparatus main body 62 and the aberration to be measured. The release time is read from the storage device 57 and set in the timer 58.

In this case, the measured aberrations include:
The aberration of the magnifying optical system 65 is included. For this reason, the aberration information of the magnifying optical system 65 is stored in the storage device 57 in advance. When each aberration is measured based on the projected image captured by the CCD 67, the arithmetic processing unit 54 stores the aberration information of the magnifying optical system 65 through the main control system 52 into the storage device 57.
Read from. The arithmetic processing unit 54 corrects the measured aberration using the aberration information of the magnifying optical system 65, and obtains the imaging characteristics of the projection optical system PLe.

Therefore, according to the second embodiment, the following effects can be obtained in addition to the effects (a) to (c) of the first embodiment. (D) In the inspection device 61 of the second embodiment, the inspection device main body 62 is provided with the vibration sensor 63 for detecting the characteristic of the vibration acting on the inspection device main body 62.

For this reason, at the time of measuring the imaging characteristics of the projection optical system PLe to be inspected, the characteristics of the vibrations actually acting on the inspection apparatus main body 62 are detected by the vibration sensor 63, and the vibrations are detected. Test pattern PA1 according to characteristics
PA4, PB1 and PB2 can set the light receiving time of the projected image. Therefore, it is possible to reliably prevent the light receiving time from being set excessively, and it is possible to more accurately measure the imaging characteristics of the test projection optical system PLe. In particular, it is possible to accurately measure the aberration based on the contrast of the projection image.

Further, the characteristic of the vibration detected by the vibration sensor 63 is the period of the vibration acting on the inspection apparatus main body 61. For this reason, based on the period of the detected vibration, the light receiving surface 42 of the imaging mechanism 64 is provided for each aberration.
Can be easily obtained.

(E) Inspection apparatus 61 of the second embodiment
Here, an enlargement optical system 65 is interposed between the light receiving surface 42 of the imaging mechanism 64 and the CCD 67. Therefore, the test patterns PA1 to PA4, PB
The projected images of PB1 and PB2 are taken in by the CCD 67 while being enlarged by the magnifying optical system 65. As a result, the resolution of the projected image on the CCD 67 is increased, and the projected image is stored in the frame memory 55 as a more accurate image. Therefore, the arithmetic processing unit 54
Can further improve the measurement accuracy of each aberration.

(Third Embodiment) Next, the third embodiment in which the exposure apparatus capable of performing the method of inspecting the projection optical system of the present invention is embodied as an exposure apparatus for manufacturing a semiconductor device will be described. The following description focuses on the differences from the inspection apparatus of the embodiment.

In the exposure apparatus 71 of the third embodiment, as shown in FIG. 9, a reticle blind 72 is provided between a pair of relay lenses 35 of the illumination optical system 32.
The reticle blind 72 is arranged such that its light-shielding surface is conjugate with the pattern area of the reticle R. In addition, the reticle blind 72 includes a plurality of movable light shielding units (for example, two L-shaped movable light shielding units) that can be opened and closed by a reticle blind driving unit 73.
By adjusting the size (slit width and the like) of the opening formed by the movable light-shielding portions, the illumination area for illuminating the reticle R can be set arbitrarily.

On the object plane side of projection optical system PL, reticle stage RST is arranged. The reticle stage RST includes test patterns PA1 to PA4, PB1,
A reticle R such as a test reticle Rt on which a PB2 is formed or a device reticle on which a device pattern is formed is exchangeably held. Further, the reticle stage RST transfers the reticle R to the projection optical system PL.
Is held movably in the X direction orthogonal to the optical axis AX. Further, the reticle stage RST can be moved in a predetermined direction (scanning direction (Y direction)) by a reticle stage driving section 74 composed of a linear motor or the like.

The reticle stage RST has a movement stroke that allows the entire surface of the reticle R to cross at least the optical axis of the illumination light IL. Note that FIG.
, The direction along the optical axis AX of the projection optical system PL is the Z direction, the direction orthogonal to the optical axis AX of the projection optical system PL and the paper is the X direction, and the paper orthogonal to the optical axis of the projection optical system PL is Is defined as a Y direction.

At the end of the reticle stage RST,
A movable mirror 76 that reflects the laser light from the laser interferometer 75 is fixed. The length measuring device 75 constantly detects the position of the reticle stage RST in the Y direction, and outputs information on the position to the main control unit 52. Then, the main control system 52 controls the reticle stage driving section 74 based on the position information of the reticle stage RST to move the reticle stage RST.

The illumination light IL that has passed through the reticle R is
The light enters the projection optical system PL. This projection optical system PL
Forms a projection image on the image plane in which the pattern on the reticle R is reduced to, for example, 1/5 or 1/4.

A wafer stage WST is arranged on the image plane side of the projection optical system PL. On the wafer stage WST, a wafer W as a substrate having a surface coated with a photoresist having photosensitivity to the illumination light IL is mounted and held via a wafer holder 77. The wafer holder 77 can be tilted in an arbitrary direction with respect to the optimum image forming plane of the projection optical system PL by a driving unit (not shown), and can be finely moved in the optical axis AX direction (Z direction) of the projection optical system PL. Has become.

The wafer stage WST is moved not only by the wafer stage drive unit 78 in the scanning direction (Y direction) but also arbitrarily by a plurality of shot areas defined on the wafer W. It is configured to be movable in a direction (X direction) orthogonal to the scanning direction.
This makes it possible to perform a step-and-repeat operation for repeating batch exposure and a step-and-scan operation for repeating scanning exposure for each shot region partitioned on the wafer W.

A movable mirror 29 for reflecting the laser beam from the length measuring device 27 is fixed to an end of the wafer stage WST. The position of the wafer stage WST in the X and Y directions is determined by the length measuring device 27. Always detected. The position information (or speed information) of wafer stage WST is transmitted to main control system 5.
2 and to the arithmetic processing unit 54 via the main control system 52. The main control system 52 controls the wafer stage driving unit 74 based on the position information (or speed information).

Here, when the pattern on the reticle R is exposed collectively to a predetermined exposure area (shot area) on the wafer W by the step-and-repeat method, the illumination area on the reticle R is changed to the reticle blind. At 72, it is shaped approximately square. Then, in a state where the reticle R and the wafer W are both stationary, an image of a pattern on the reticle R in this illumination area is projected onto the projection optical system PL.
Are projected onto the shot area on the wafer W at a time.

On the other hand, when the pattern on the reticle R is scanned and exposed on the shot area on the wafer W by the step-and-scan method, the illumination area on the reticle R is shaped like a rectangle (slit) by the reticle blind 72. Is formatted. This illumination area has a longitudinal direction perpendicular to the scanning direction (+ Y direction) on the reticle R side. By scanning the reticle R at a predetermined speed Vr during exposure, the circuit pattern on the reticle R is sequentially illuminated from one end to the other end in the slit-shaped illumination area. Thus, the pattern on the reticle R in the illumination area is projected onto the wafer W via the projection optical system PL, and a projection area is formed.

Here, since the wafer W has an inverted image relationship with the reticle R, a predetermined speed is synchronized with the scanning of the reticle R in a direction (-Y direction) opposite to the scanning direction of the reticle R. Scan with Vw. As a result, the entire surface of the shot area of the wafer W can be exposed. Scanning speed ratio V
The ratio w / Vr accurately corresponds to the reduction magnification of the projection optical system PL, and the circuit pattern on the reticle R is accurately reduced and transferred onto each shot area on the wafer W.

Above the wafer stage WST, a focus position detection system 81 including a pair of a light transmission system 79 and a light reception system 80 is provided so as to sandwich the projection optical system PL. The light transmitting system 79 obliquely emits measurement light having a wavelength at which the photoresist is not exposed to the surface of the wafer W. The light receiving system 80 receives the reflected light of the measurement light from the surface of the wafer W, and detects a focus position (a position in the Z direction) on the surface of the wafer W based on the light receiving position of the reflected light. Then, information on the detected focus position is input to the arithmetic processing unit 54 of the aberration detecting unit 53 via the main control system 52 and the main control system 52.

As shown in FIGS. 9 and 10, an imaging mechanism 8 for measuring the imaging characteristics of the projection optical system PL.
Numeral 4 is detachably mounted in the mounting recess 85 on the wafer stage WST so that the surface 86 thereof substantially matches the height of the surface of the wafer W. On the surface 86 of the imaging mechanism 84, the test patterns PA
A plurality of slits 87 are formed as a plurality of light receiving surfaces so as to substantially correspond to the size of one light shielding portion Ps 1 to PA4, PB1 and PB2. An image pickup device (CCD) 88 is arranged at a position corresponding to each slit 87 in the image pickup mechanism 84. The CCD 88 is connected to the frame memory 5.
5 is connected.

In the image pickup mechanism 84, the projected images of the test patterns PA1 to PA4, PB1 and PB2 are captured as follows. That is, as shown in FIGS. 9 and 11, first, the wafer stage WST is moved so that the slits 87 of the image pickup mechanism 84 are projected into the projectable range of the projection optical system PL. It is arranged at a scanning start position P1 near any one of PA4, PB1 and PB2. Next, the main control system 52 reads out the relative movement speed between the projection image and the slit 87 stored in advance for each aberration to be measured from the storage device 57. The main control system 52 sends the wafer stage W to the wafer stage driving unit 78.
When the movement of ST is instructed, the slit 87 is moved to the scanning end position P with the relative movement speed along the arrangement direction of the projection images Ps' corresponding to the light shielding portions Ps with respect to the projection images.
Move to 2.

As a result, the projection images Ps ′ corresponding to the light-shielding portions Ps sequentially pass over the slits 87, and the CCD 88 captures the projection images. Then, in the aberration detecting section 53, similarly to the first embodiment, the imaging characteristics of the projection optical system PL are measured based on the captured projection image. As described above, in the third embodiment, the light receiving time of the projected images of the test patterns PA1 to PA4, PB1 and PB2 in the slit 87 of the imaging mechanism 84 is measured for each aberration to be measured, and the projected image and the slit 87 are measured. It is configured to be changed by changing the relative moving speed with respect to.

In the exposure apparatus of the third embodiment,
The amount of light in the projection image incident on the slit 87 of the imaging mechanism 84 is adjusted by changing the number of pulses of the illumination light IL to the light source 33 that emits the illumination light IL according to a command from the main control system 52. Has become. Here, the light source 33 constitutes a light amount changing unit.

Further, as shown in FIG.
Is connected to an imaging characteristic control unit 89 that controls the imaging characteristics of the projection optical system PL based on each aberration measured by the arithmetic processing unit 54 of the aberration detection unit 53.
The imaging characteristic control unit 89 includes a driving element 9 such as a piezo element for changing an interval between a plurality of lens elements 91 housed in a lens barrel 90 of the projection optical system PL.
2 are connected. Further, a pressure controller 93 for adjusting the pressure in the lens barrel 90 of the projection optical system PL is connected to the imaging characteristic controller 89. The image forming characteristic control system 89, the drive element 92, and the pressure control unit 93 constitute a correction unit.

Here, the main control system 52 sends the driving element 92 and the pressure control unit 93 to the imaging characteristic control unit 89 based on the input information on each aberration of the projection optical system PL. Command. Thereby, the relative position of each lens element 91 is changed, the pressure in the lens barrel 90 of the projection optical system PL is adjusted, and the imaging characteristics of the projection optical system PL are corrected. .

Therefore, according to the third embodiment, the following effects can be obtained in addition to the effects substantially the same as those described in (a) to (c) in the first embodiment. .

(F) Exposure apparatus 71 of the third embodiment
In, the imaging characteristics of the projection optical system PL are corrected based on the aberration measured by the aberration detection unit 53.
Therefore, each aberration present in the projection optical system PL can be accurately measured without using an expensive active anti-vibration device, and the imaging characteristics of the projection optical system PL can be accurately corrected. . Therefore, the pattern formed on the reticle R can be accurately projected and transferred onto the wafer W, and the yield on the product wafer can be improved.

(G) Exposure apparatus 71 of the third embodiment
Then, the light amount adjustment of the projection image incident on the slit 87 of the imaging mechanism 84 is performed by changing the pulse number of the illumination light IL to the light source 33 that emits the illumination light IL in accordance with a command from the main control system 52. It has become.

For this reason, the slit 8 of the image pickup mechanism 84
In the case where the light receiving time of the projection image via the light source 4 is extended, it is possible to prevent the CCD 88 from becoming saturated without increasing the number of components and complicating the configuration.

(Modification) The embodiment of the present invention may be modified as follows. In the above embodiments, the test patterns PA1 to PA
4, PB1 and PB2 use a dark line pattern in which a plurality of linear light shielding portions Ps are arranged at predetermined intervals in the light transmitting portion Pt. On the other hand, test patterns PA1 to PA
4, a bright line pattern in which a plurality of linear light transmitting portions Pt are arranged at predetermined intervals in the light shielding portion Ps may be used as PB1 and PB2.

With this configuration, substantially the same effects as in the above embodiments can be obtained. In particular, in the third embodiment, the test patterns PA1 to PA4, PB1,
The projected image of B2 and the slit 87 of the imaging mechanism 84 are relatively moved, and the projected image is transferred to the CCD through the slit 87.
By taking in at 88, information on the imaging characteristics of the projection optical system PL is obtained. Therefore, the third
In the embodiment, when this bright line pattern is used, the slit 87 is moved to the scanning start position P1 and the scanning end position P1.
2, the slit 87 can be made to coincide with the portion corresponding to the light shielding portion Ps of the projected image.
Thereby, the scanning start position P1 and the scanning end position P
In 2, the light beam received by the CCD 88 hardly exists. Therefore, the shutter mechanism 39 is not required,
The configuration and control of the exposure device 71 can be simplified.

In the above embodiments, the projected images of the test patterns PA1 to PA4, PB1 and PB2 are taken by the imaging mechanism 4
The configuration is such that the aberrations of the projection optical systems PLe, PL are measured by capturing the images at 1, 64, 84 and performing image processing. On the other hand, test patterns PA1 to PA4,
The images of PB1 and PB2 are printed on the wafer W coated with the photoresist via the projection optical systems PLe and PL. Then, the printed image of the pattern may be developed, and the developed pattern image may be visually observed with an electron microscope or the like to measure each aberration of the projection optical system.

With this configuration, substantially the same effects as those of the above embodiments can be obtained except for the above (e). In the above embodiments, the illumination light IL is pulsed light such as excimer laser light. However, for example, visible light or ultraviolet light such as g-line, h-line, i-line, or the like, metal vapor laser light, YAG
It may be a continuous light such as a harmonic of a continuous laser beam such as a laser beam, a solid-state laser beam, or a fiber laser beam, or extreme ultraviolet light.

Even with this configuration, substantially the same effects as those of the above-described embodiments can be obtained except for the above (g).・
In each of the above embodiments, the CCD 67, 88 is used as an image sensor.
, For example, BBD type, CID type, CPD type,
MOS-type, PCD-type image sensors, photomultipliers,
A line sensor or the like may be employed.

In this case, substantially the same effects as those of the above embodiments can be obtained. In each of the above embodiments, the light amount adjustment in the projected image incident on the light receiving surface 42 or the slit 87 of the imaging mechanism 41, 64, 84 is performed by changing the neutral density filter 44 or the illumination light emitted from the light source 33. This is performed by changing the number of IL pulses. On the other hand, for example, by using a grating type energy modulator in which a plurality of lattice plates on which light transmitting portions and light shielding portions are formed at a predetermined pitch are stacked so as to be relatively movable in the pitch direction of the lattice. The light amount adjustment may be performed. Further, two optical element plates transparent to the illumination light IL having antireflection coating on both surfaces are arranged so that the inclination angle with respect to the illumination light IL is symmetrical and changeable, and the inclination angle is changed. The light amount adjustment may be performed using an energy modulator or the like that changes the energy of the illumination light IL.

With this configuration, substantially the same effects as those of the above embodiments can be obtained. In the second embodiment, an output signal from the vibration sensor 63 in a state where vibration is not received is stored in the main control system 52 or the storage device 57 in advance as a reference value. Then, projection images of the test patterns PA1 to PA2, PB1, and PB2 are captured at a certain time when the output signal from the vibration sensor 63, that is, the period of the vibration acting on the board 24 is within a predetermined range from the reference value. Captured by the mechanism 64. The imaging characteristics of the test projection optical system PLe may be measured based on the projection image thus captured. In this case, since the measurement of the imaging characteristics is performed in a state where the vibration is small, the imaging mechanism 6 is used.
The light receiving time in 4 may be extended in the same manner as in each of the above embodiments, or may be reduced to such a degree that a sufficient resolving power is obtained by the imaging mechanism 64.

Further, the imaging mechanism 64 constantly captures the projected images of the test patterns PA1 to PA2, PB1 and PB2 by receiving light for a short period of time such that a sufficient resolving power can be obtained by the imaging mechanism 64. To be stored. The output signal from the vibration sensor 63 synchronized with the capture of the projection image is also stored in the frame memory 55 at the same time. Then, the projection image when the output signal from the vibration sensor 63 is within a predetermined range from the reference value is extracted from the frame memory 55, and the imaging characteristics of the projection optical system PLe are measured. You may.

With such a configuration, even when the noise component is superimposed on the vibration acting on the inspection apparatus main body 62 and the period of the vibration is not constant, accurate aberration measurement can be performed. .

In the second embodiment, the aberration measured based on the projected image captured by the CCD 67 is corrected by using the aberration of the magnifying optical system 65 stored in the storage device 57 in advance. It is supposed to. On the other hand, for example, a rotation mechanism for rotating the magnifying optical system 65 by a predetermined angle is provided, the magnifying optical system 65 is arranged at a position different by 180 °, and the imaging characteristics are measured for each. Then, the influence of the aberration of the magnifying optical system 65 may be eliminated by calculating the average of the two measurement results. Similarly, by rotating the test projection optical system PLe, measuring the imaging characteristics thereof, and calculating the average of the measurement results, the influence of the aberration of the magnifying optical system 65 is eliminated. You may.

With this configuration, substantially the same effects as in the second embodiment can be obtained. In the third embodiment, the test patterns PA1 to PA4 and PB in the slit 87 of the imaging mechanism 84 are used.
The light receiving time of the projected images 1 and PB2 was changed by changing the relative moving speed between the projected image and the slit 87 for each aberration to be measured. On the other hand, a counter is provided in the main control system 52, the relative movement speed is always constant, and the relative distance between the projection image and the slit 87 is calculated based on the count of the counter for each aberration to be measured. The light receiving time of the projection image may be changed by changing the number of times of movement.

In the third embodiment, the projection images of the test patterns PA1 to PA4, PB1 and PB2 are kept stationary, and the wafer stage WST is moved, so that the slit 87 of the imaging mechanism 84 is moved. The projected image is taken in by the CCD 88 through the slit 87. On the other hand, the slit 87
May be stationary, and the reticle stage RST may be moved to move the projection image and capture the projection image. Also, both stages RST,
By relatively moving WST while synchronizing, the projected image and the slit 87 may be relatively moved to capture the projected image.

In the third embodiment, the projected images of the test patterns PA1 to PA4, PB1 and PB2 are taken in by the CCD 88 through the slit 87 formed on the surface 86 of the imaging mechanism 84. . On the other hand, for example, a rectangular opening is provided on the surface 86 of the imaging mechanism 84, and the projection image is taken in by the CCD 88 through the opening while relatively moving the opening and the projection image. Is also good.

In the third embodiment, a specific example of the exposure apparatus having the projection optical system PL for reducing and projecting the image of the pattern on the reticle R onto the wafer W has been described.
On the other hand, the present invention may be embodied in an exposure apparatus having a projection optical system for projecting the pattern image onto the wafer W at the same magnification or magnification.

In the third embodiment, a specific example of the exposure apparatus for manufacturing a semiconductor device has been described. On the other hand, the present invention is intended for manufacturing other microdevices such as a liquid crystal display device, a thin film magnetic head, and an imaging device, or
The present invention may be embodied in an exposure apparatus for manufacturing a mask such as a reticle and a photomask.

With such a configuration, substantially the same effects as in the third embodiment can be obtained. Further, the projection optical systems PL and PLe are not limited to those in which all the optical elements are constituted by refraction lenses, but are constituted by reflection elements (mirrors) or refraction lenses and reflection elements. It may be a catadioptric system. Further, the present invention is not limited to the reduction system, and may be an equal magnification system or an enlargement system.

The inspection devices 21 and 61 and the exposure device 71 of each of the embodiments described above are capable of performing various subsystems including the components described in the claims of the present application with predetermined mechanical accuracy,
It is manufactured by assembling to maintain electrical and optical accuracy. Before and after this assembly, in order to ensure these various precisions, adjustments to achieve optical precision for various optical systems, adjustments to achieve mechanical precision for various mechanical systems, and various electrical systems Are adjusted to achieve electrical accuracy. The process of assembling the inspection devices 21 and 61 and the exposure device 71 from the various subsystems includes mechanical connections, electrical circuit connections, and pneumatic circuit piping connections between the various subsystems. Inspection devices 21 and 61 and exposure device 7
It goes without saying that there is an individual assembly process for each subsystem before the assembly process into one. When the assembly process of the various subsystems into the inspection devices 21 and 61 and the exposure device 71 is completed, comprehensive adjustment is performed, and the inspection devices 21 and 61 are exposed.
Various accuracies of the exposure apparatus 61 and the exposure apparatus 71 as a whole are secured. It is desirable that the inspection devices 21 and 61 and the exposure device 71 be manufactured in a clean room in which temperature, cleanliness, and the like are controlled.

The semiconductor device includes a step of designing the function and performance of the device, a step of manufacturing a reticle R based on the design step, and a step of designing a wafer W from a silicon material.
, A step of exposing the pattern of the reticle R to the wafer W by the exposure apparatus 71 of the embodiment, a device assembling step (including a dicing step, a bonding step, and a package step), an inspection step, and the like. The illumination optical system composed of a plurality of lenses and the projection optical system PL are incorporated in the main body of the exposure apparatus 71 for optical adjustment, and a reticle stage RST and a wafer stage WST composed of a large number of mechanical parts are attached to the main body of the exposure apparatus 71. The exposure apparatus 71 of the above embodiment can be manufactured by connecting wires and pipes and performing overall adjustment (electrical adjustment, operation confirmation, etc.).
It is desirable to manufacture the exposure apparatus 71 in a clean room where the temperature, cleanliness, and the like are controlled.

Next, technical ideas that can be understood from the above embodiments and modified examples will be described below together with their effects. (1) When the characteristics of the vibration include at least the period of the vibration, the optimum light receiving time on the light receiving surface for each imaging characteristic can be easily obtained based on the period of the vibration. Is obtained.

(2) When the illumination light is pulsed light, and the light amount changing means controls the number of pulses of the pulsed light with respect to a light source that emits the pulsed light, the light amount changing means may be used when an image sensor is used. Thus, it is possible to prevent the image pickup device from becoming saturated without increasing the number of components and complicating the configuration.

[0130]

As described in detail above, according to the first and sixth aspects of the present invention, inspection is performed for each type of image forming characteristic and for each characteristic of vibration acting on the inspection apparatus. The projected image of the application pattern can be formed in the best state. Therefore, it is possible to eliminate the influence of low-frequency vibration during the inspection of the projection optical system without using an expensive anti-vibration device, and to accurately measure the imaging characteristics of the projection optical system.

According to the invention of claim 2 of the present application, in addition to the effects of the invention of claim 1, the inspection pattern can be changed according to the characteristics of the vibration actually acting on the inspection apparatus. By setting the projection time of the projection image, the imaging characteristics of the projection optical system can be measured more accurately.

According to the invention described in claim 3 of the present application, in addition to the effects of the invention described in claim 1 or 2, the projection optical system can be adapted in accordance with the state of use of the projection optical system. Can be easily and accurately measured.

According to the invention described in claim 4 of the present application, in addition to the effect of the invention described in claim 3, in addition to the simple configuration of simply changing the light receiving time of the projected image of the inspection pattern, the invention has a low The influence of frequency vibration can be eliminated. Therefore, an accurate inspection of the projection optical system can be performed without increasing the number of parts and complicating the configuration.

According to the invention of claim 5 of the present application, in addition to the effects of the invention of any one of claims 1 to 4, for example, an inspection pattern using an image pickup device is used. When the projection image is received, it is possible to prevent the imaging device from becoming saturated. Therefore, the imaging characteristics of the projection optical system can be accurately measured.

According to the seventh aspect of the present invention, the imaging characteristics of the projection optical system can be accurately measured without using an expensive anti-vibration device, and an accurate exposure operation is ensured. can do. Therefore, the yield on the product substrate can be improved.

According to the eighth aspect of the present invention, the circuit pattern on the mask can be accurately transferred onto the substrate, and the yield on the product substrate can be improved.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing a projection optical system inspection apparatus according to a first embodiment.

FIG. 2 is a schematic configuration diagram showing the inspection apparatus of FIG. 1;

FIG. 3 is an enlarged plan view showing a test pattern.

FIG. 4 is a plan view showing a test reticle.

FIG. 5 is an explanatory diagram relating to image processing of a projected image of a test pattern.

FIG. 6 is an explanatory diagram showing a relationship between a cycle of vibration and a light receiving time.

FIG. 7 is a partially cutaway front view showing a projection optical system inspection apparatus according to a second embodiment.

FIG. 8 is a schematic configuration diagram showing the inspection device of FIG. 7;

FIG. 9 is a schematic configuration diagram illustrating an exposure apparatus according to a third embodiment.

FIG. 10 is an enlarged partial sectional view showing a main part of FIG. 9;

FIG. 11 is an explanatory diagram relating to a relative movement between a projection image and a slit.

DESCRIPTION OF SYMBOLS 21, 61: Inspection device, 32: Illumination optical system, 33: Light source constituting light amount changing means, 42: Light receiving surface, 43: Light reducing plate constituting light amount changing means, 52: Control means Main control system, 53 ... aberration detection unit constituting measuring means, 63 ...
Vibration sensor as detecting means, 71 ... Exposure device, 87 ...
A slit as a light receiving surface, 89: an imaging characteristic control unit forming a part of the correction unit, 92: a driving element forming a part of the correction unit, 93: a pressure control unit forming a part of the correction unit, PA1 ~ PA4, PB1, PB2 ... test pattern as inspection pattern, PL ... projection optical system, PLe ...
A projection optical system to be inspected as a projection optical system, R: a reticle as a mask, Rt: a test reticle as a mask for inspection, W: a wafer as a substrate.

Claims (8)

[Claims] An illumination optical system for illuminating an inspection mask having an inspection pattern, a projection optical system for projecting the inspection pattern on a predetermined surface, and an illumination optical system for projecting the inspection pattern on the predetermined surface. In an inspection apparatus for a projection optical system, comprising: a measurement unit configured to measure an imaging characteristic of the projection optical system based on a projection image; and a type of an imaging characteristic of the projection optical system to be measured by the measurement unit. An inspection apparatus for a projection optical system, comprising: control means for changing a projection time of the projection image projected on the predetermined surface in accordance with at least one of characteristics of vibration acting on the inspection apparatus. . 2. The apparatus according to claim 1, further comprising a detecting unit configured to detect a characteristic of the vibration. 3. The inspection apparatus for a projection optical system according to claim 1, wherein a light receiving surface for receiving the projection image is disposed on the predetermined surface. 4. The inspection apparatus for a projection optical system according to claim 3, wherein the control unit changes a light receiving time on the light receiving surface as the projection time. 5. The inspection of the projection optical system according to claim 1, further comprising a light amount changing unit that changes a light amount of the light beam incident on the light receiving surface. apparatus. 6. An inspection pattern formed on an inspection mask is projected onto a predetermined surface via a projection optical system, and an imaging characteristic of the projection optical system is measured based on a projected image of the inspection pattern. In the inspection method of the projection optical system measured by the means, the type of the imaging characteristic of the projection optical system to be measured by the measurement means, and the vibration acting when projecting the inspection pattern on the predetermined surface A projection time of the projection image projected onto the predetermined surface is changed according to at least one of the following characteristics: 7. An exposure apparatus for transferring a pattern formed on a mask onto a substrate via a projection optical system, wherein the inspection of the projection optical system according to any one of claims 1 to 5. An exposure apparatus comprising: an apparatus; and a correction unit configured to correct an imaging characteristic of the projection optical system based on an inspection result of the inspection apparatus. 8. A method for manufacturing a micro device, wherein a device pattern formed on a mask is transferred onto a substrate via a projection optical system to form a predetermined circuit pattern on the substrate, the method comprising: According to at least one of a type of an imaging characteristic of the projection optical system and a characteristic of vibration acting when projecting the inspection pattern on the inspection mask onto a predetermined surface via the projection optical system, Changing the projection time of the projection image of the inspection pattern projected on the surface, projecting the inspection pattern on the predetermined surface, and connecting the projection optical system based on the projection image after the change of the projection time. Measuring the image characteristics, correcting the imaging characteristics of the projection optical system based on the measurement results, and transferring the device pattern on the mask onto the substrate. .