JP2001028328A - Method and device for scanning aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a scanning aligner and exposure method, where thermal deformation state of a mask is monitored at always, and based on the monitoring result, the imaging characteristics of a projection optical system is accurately corrected. SOLUTION: While a reticle R and a wafer W are moved synchronously, the image of a pattern formed on the reticle R is scanned and exposed on the wafer W via a projection optical system 24. During the scanning exposure, the image of a periodic pattern 33, comprising a rod-like mark 33a formed on the reticle R, is detected with a photodetector 34. As a reticle stage is 19 moved, a reference phase cycle which is a reference for scanning exposure is generated, using an interferometer 22A. Phase difference between a detection phase cycle and a reference phase cycle is detected, based on the image of the periodic pattern 33 by a main control system 23, and based on the detection result, the imaging characteristics of the projection optical system 24 are corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used, for example, 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, and an imaging device, and in a manufacturing process of a mask such as a reticle and a photomask. The present invention relates to a scanning type exposure apparatus and an exposure method.

[0002]

2. Description of the Related Art In a scanning exposure apparatus of this type, an image of a pattern formed on a reticle is projected via a projection optical system while a reticle as a mask and a wafer as a substrate are moved synchronously. Scanning exposure is performed on the wafer. In this type of exposure apparatus, in order to form a circuit pattern of a semiconductor element or the like on a wafer with high accuracy, it is necessary to form an image such as a magnification and a focus position in a projection optical system with the accuracy of synchronous movement between the reticle and wafer. It is necessary to project an image of a pattern on a reticle onto a wafer while maintaining characteristics in a predetermined state.

However, in this exposure apparatus, the reticle and the projection optical system absorb the exposure light during the exposure, so that the reticle and the optical elements of the projection optical system may be thermally deformed. For this reason, the synchronization accuracy between the image of the pattern on the reticle and the wafer during the scanning exposure and the imaging characteristics of the projection optical system change, and the accuracy of the scanning exposure decreases. Then, there is a possibility that the yield of manufactured product wafers may be reduced.

Therefore, the following method has conventionally been proposed in order to correct such a change in the imaging characteristics due to absorption of exposure light in such a reticle or projection optical system. That is, regarding the exposure light absorption of the projection optical system,
For example, JP-A-60-78455 and JP-A-63-78455
Japanese Patent Application Laid-Open No. 58349 discloses an exposure apparatus including a mechanism for detecting the amount of exposure light incident on a projection optical system and correcting a change in optical characteristics of the projection optical system. Also,
Regarding the exposure light absorption of the reticle, see, for example,
Japanese Patent Application Laid-Open No. 92317 discloses an exposure apparatus including a mechanism for calculating the amount of thermal deformation of a reticle by calculation and correcting the optical characteristics of a projection optical system according to the calculation result.

In general, thermal deformation of a reticle is caused by the fact that a light-shielding member of a circuit pattern formed of a metal film such as chromium formed on the reticle absorbs exposure light, and the reticle glass substrate made of quartz glass or the like undergoes thermal expansion. It is caused by things.
For this reason, conventionally, it corresponds to various information such as the material of the light shielding member, the absorptance of the exposure light beam, the density distribution of the circuit pattern (pattern abundance ratio), the power of the light source, and the fluctuation characteristics of the thermal deformation which are obtained in advance. Using the model, the thermal expansion amount of the reticle was calculated.

[0006] The change in the imaging characteristics caused by thermal deformation of the reticle is mainly a change in magnification due to thermal expansion of the entire reticle. For this reason, conventionally, the distance between the optical elements in the projection optical system is changed in the optical axis direction, or by changing the pressure in the lens barrel of the projection optical system,
The image forming characteristic of the projection optical system is corrected so as to cancel the change in the image forming characteristic. Note that the magnification change in this case refers to a case where the size of an image of a pattern exposed on a wafer changes from a design reference dimension due to thermal expansion of a reticle, even when the projection magnification of a projection optical system does not change. Is included.

[0007]

In recent years, the microdevices have been highly integrated. In particular, in a semiconductor element, the circuit pattern has become extremely fine, and the number of superposed patterns has been increasing. For this reason, the permissible width for the displacement of each pattern formed on the wafer is becoming smaller and smaller. In other words, for example, even if the magnification of the pattern image is slightly deviated, there is a possibility that a connection failure or insulation failure between a plurality of layers may occur due to the stacking.

However, in each of the above-mentioned conventional configurations, the amount of thermal expansion of the reticle is obtained by calculation or the like, and the imaging characteristics of the projection optical system are corrected in advance according to the calculation result. . In other words, each of the conventional configurations corrects the imaging characteristics of the projection optical system based on the amount of thermal expansion calculated according to a predetermined model, and thereafter, for a predetermined period, does not perform correction of the imaging characteristics without changing the product wafer. Will be manufactured. As described above, each of the conventional configurations is so-called open control in which the calculation of the coefficient of thermal expansion and the correction of the imaging characteristics are performed discretely.

Here, even if the calculation of the coefficient of thermal expansion and the correction of the imaging characteristics are performed, for example, once per processing lot of a product wafer, the reticle is continuously irradiated with exposure light. The amount of thermal expansion changes every moment, albeit little by little. For this reason, in the lot, a magnification shift of the pattern image occurs due to the thermal deformation of the reticle. As described above, in each of the conventional configurations, there is a problem that a sufficient yield improvement effect on a product wafer may not be expected in the flow of the recent miniaturization of circuit patterns as described above.

The present invention has been made by paying attention to such problems existing in the prior art. It is an object of the present invention to provide a scanning exposure apparatus and an exposure method that can constantly monitor thermal deformation of a mask with a simple configuration and accurately correct an imaging characteristic of a projection optical system based on the monitoring result. Is to provide.

[0011]

According to a first aspect of the present invention, there is provided a scanning exposure apparatus, wherein a mask (R) and a substrate (W) are moved synchronously. A scanning type exposure apparatus which scans and exposes an image of a pattern formed on the mask (R) onto the substrate (W), wherein a predetermined phase period (L1) is formed on the mask (R). First cycle generating means (33) for generating
A cycle detecting means (34) for detecting the predetermined phase cycle (L1); and a second cycle generating means (22A, 30) for generating a reference phase cycle (L2) serving as a reference for the scanning exposure.
A) and a phase difference detecting means (2) for detecting a phase difference between the predetermined phase cycle (L1) and the reference phase cycle (L2).
3).

According to the first aspect of the present invention, a predetermined phase period generated from the first period generating means formed on the mask during the scanning exposure is detected by the period detecting means. Further, a reference phase cycle serving as a reference for the scanning exposure is generated by the second cycle generating means. Then, a phase difference between the predetermined phase cycle and the reference phase cycle is detected by a phase difference detecting means. For this reason, the thermal deformation state of the mask can be constantly monitored based on the variation of the phase difference, and it is easy to change the imaging characteristic of the projection optical system due to the thermal deformation of the mask. Can be detected.

According to a second aspect of the present invention, in the first aspect, the first period generating means (33) includes a periodic pattern (33) formed on the mask (R). And the period detecting means (34) includes a light receiver (34) for receiving an image of the periodic pattern (33) in the scanning exposure.

According to the second aspect of the present invention, in addition to the operation of the first aspect of the present invention, by using a light receiver such as a CCD camera, a predetermined light generated from a periodic pattern on a mask can be obtained. Variations in the phase period can be easily measured.

The invention according to claim 3 of the present application is the invention according to claim 2, wherein the periodic pattern (3
3) a bar mark (33a) extending along a direction orthogonal to the moving direction of the mask (R) during the scanning exposure and arranged at a predetermined interval along the moving direction. It is characterized by the following.

According to the third aspect of the present invention, in addition to the operation of the second aspect of the present invention, a predetermined phase period can be generated with a simple configuration. Can be avoided.

Further, the invention according to claim 4 of the present application is the invention according to claim 3, wherein the periodic pattern (3
3) is replaced with the device pattern (1) on the mask (R).
7) The region is arranged outside in the direction orthogonal to the moving direction of the mask (R).

According to the fourth aspect of the present invention, in addition to the function of the third aspect, even during exposure of a device pattern on a mask, a periodic pattern arranged outside the device pattern is also provided. Thereby, the thermal deformation state of the mask can be constantly monitored.

According to a fifth aspect of the present invention, in accordance with the first aspect of the present invention, there is provided a mask stage (10) on which the mask (R) is placed and moved. 19) and a substrate stage (27) on which the substrate (W) is placed and moved, and wherein the second cycle generating means (22A, 30A) includes the mask stage (1).
9) Alternatively, the reference phase period (L2) is generated with the movement of the substrate stage (27).

According to a fifth aspect of the present invention, in addition to the operation of the first aspect, the reference phase period associated with the movement of the mask stage or the substrate stage. By calculating the phase difference of the predetermined phase period with respect to the above, the thermal deformation state of the mask can be accurately detected.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the second period generating means (L2) includes a mask (R) or a substrate (W) for the scanning exposure. The mask stage in the moving direction of the mask stage (19)
Alternatively, it comprises an interferometer (22A, 30A) for detecting the position of the substrate stage (27).

According to the sixth aspect of the present invention, in addition to the operation of the fifth aspect of the present invention, the phase difference is detected by utilizing a synchronization signal for detecting the position of the mask stage or the substrate stage. You can ask.

According to a seventh aspect of the present invention, in the first aspect of the present invention, the pattern of the mask (R) is changed to the substrate (W).
Correction means (20, 20) having a projection optical system (24) for projecting the light onto the projection optical system (24), and correcting the imaging characteristics of the projection optical system (24) based on the detection result of the phase difference detection means (23)
28, 31, 32).

According to the seventh aspect of the present invention, in addition to the operation of the first aspect of the present invention, the thermal deformation state of the mask is constantly monitored, and The imaging characteristics of the projection optical system can be accurately corrected based on the monitoring result.

According to the invention described in claim 8 of the present application, in the invention described in any one of claims 5 to 7, the phase difference detecting means (23) is provided with the predetermined phase period. And detecting a phase difference between (L1) and the reference phase period (L2) generated with the movement of the mask stage (19).

According to an eighth aspect of the present invention, in addition to the operation of the fifth aspect, the reference phase generated by the movement of the mask stage is provided. By calculating the phase difference using the period,
The influence of a synchronization error between the mask stage and the substrate stage can be eliminated. For this reason, the thermal deformation state of the mask can be detected more accurately.

According to a ninth aspect of the present invention, in accordance with the seventh or eighth aspect, the correction means (20, 28, 31, 32) includes the projection optical system (24). Wherein the magnification component of the imaging characteristics is corrected.

According to the ninth aspect of the present invention, in addition to the effects of the seventh or eighth aspect,
By correcting the magnification component of the projection optical system, the imaging characteristics of the projection optical system caused by the thermal deformation of the mask can be easily corrected.

The invention according to claim 10 of the present application is the invention according to any one of claims 7 to 9, wherein the correction means (20, 28) includes the mask stage (19). ) And at least one of the moving speeds of the substrate stage (27) is corrected.

According to the tenth aspect of the present invention, in addition to the operation of the seventh aspect, the moving speed of at least one of the mask stage and the substrate stage is reduced. By performing the correction, it is possible to easily correct the imaging characteristic of the projection optical system caused by the thermal deformation of the mask.

[0031] The invention according to claim 11 of the present invention relating to the exposing method is characterized in that an image of a pattern formed on the mask (R) is formed while the mask (R) and the substrate (W) are moved synchronously. In an exposure method for performing scanning exposure on said substrate (W) via a projection optical system (24), a predetermined phase period (L1) is set by a first period generating means (33) formed on said mask (R). The predetermined phase period (L1) is detected by the period detecting means (34), and the second
A cycle generating means (22A, 30A) generates a reference phase cycle (L2) as a reference for the scanning exposure, and detects a phase difference between the predetermined phase cycle (L1) and the reference phase cycle (L2). The imaging characteristic of the projection optical system (24) is detected by the means (23) and corrected based on the detection result of the phase difference detecting means (23).

According to the eleventh aspect of the present invention, the thermal deformation state of the mask can be monitored at all times, and the imaging characteristics of the projection optical system can be accurately corrected based on the monitoring result. Can be performed.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a scanning exposure apparatus (hereinafter simply referred to as "exposure apparatus") for manufacturing a semiconductor device will be described below with reference to FIGS. I do.

As shown in FIG. 1, a KrF excimer laser beam, an ArF excimer laser beam,
Exposure light EL such as F ₂ excimer laser light is formed with a uniform illuminance via the fly-eye lens 12. Then, the exposure light EL emitted from the fly-eye lens 12 enters the reticle R as a mask via the relay lenses 13 and 14, the mirror 15, and the condenser lens 16.
As shown in FIGS. 2 and 3, this reticle R is a device pattern 1 such as a circuit pattern made of a metal film such as chromium on a reticle substrate Rp made of quartz glass, fluorite or the like.
7 are formed.

As shown in FIGS. 1 and 2, the reticle R is mounted on a reticle stage 19 as a mask stage provided on a base 18. The reticle stage 19 is moved in a predetermined scanning direction (Y direction in FIG. 1) in a plane orthogonal to the optical axis AX of the exposure light EL on the base 18 by a reticle stage driving unit 20 which constitutes a correcting means such as a motor. To be moved to The reticle stage 19 is provided with the exposure light E
In order to position the reticle R in a plane orthogonal to the optical axis AX of L, the reticle R is configured to be finely movable in a direction (X direction) orthogonal to the scanning direction (Y direction).

The movable mirrors 21A and 21B are fixed to the end of the reticle stage 19, and these movable mirrors 21A and 21B are fixed.
Interferometers 22A and 22B are arranged near the reticle stage 19 so as to face the reticle stage 19B, respectively. These interferometers 22A and 22B are
A, 21B is irradiated with, for example, He-Ne laser light, and a predetermined reference phase periodic signal is generated based on interference of the incoming and reflected laser light. The position of the reticle stage 19 in the scanning direction and the direction orthogonal thereto is constantly detected based on the reference phase period signal, and the position information is used as main control constituting phase difference detection means for controlling the operation of the entire exposure apparatus. Output to the system 23. The main control system 23 drives and controls the reticle stage drive unit 20 based on the position information of the reticle stage 19, and moves the reticle stage 19 so that the reticle R is positioned at a predetermined position.

The exposure light having passed through the reticle R enters a projection optical system 24 having a plurality of lens elements 24b and the like in a lens barrel 24a. This projection optical system 24
Are arranged such that the optical axis thereof coincides with the optical axis AX of the exposure light EL. Then, the projection optical system 24 is a wafer as a substrate on the surface of which a projection image obtained by reducing the device pattern 17 on the reticle R to, for example, 1/4 is coated with a photoresist having photosensitivity to the exposure light EL. It is formed on W.

The wafer W is mounted on a wafer stage 27 as a substrate stage via a wafer holder 26. The wafer stage 27 can be tilted in an arbitrary direction with respect to the optimum image forming plane of the projection optical system 24 by a wafer stage driving unit 28 which constitutes a correcting means such as a motor, and the optical axis direction of the projection optical system 24 (Z direction). Further, the wafer stage 27 is moved in the scanning direction (Y direction) in synchronization with the movement of the reticle stage 19 by the wafer stage drive unit 28, and is moved in a direction (X direction) orthogonal to the scanning direction (Y direction).
Direction). This allows
A step-and-scan operation that repeats an operation of scanning and exposing a predetermined shot area partitioned on the wafer W and an operation of moving to a start position of the next scanning exposure is performed.

At the end of the wafer stage 27, movable mirrors 29A and 29B are fixed.
9B so as to face each other.
Are interferometers 30A and 30B. These interferometers 30A, 30B are provided with the movable mirrors 29A, 2B.
9B is irradiated with, for example, He-Ne laser light, and a predetermined reference phase periodic signal is generated based on interference of the incoming and reflected laser light. Then, the position of the wafer stage 27 in the scanning direction and its orthogonal direction is constantly detected based on the reference phase period signal, and the position information is output to the main control system 23 which controls the operation of the entire exposure apparatus. The main control system 23 drives and controls the wafer stage driving unit 28 based on the position information of the wafer stage 27,
The wafer stage 27 is moved so that the wafer W is positioned at a predetermined position.

The projection optical system 24 includes the main control system 2
Under the control of (3), a lens interval control unit 31 is connected as correction means for changing the interval between the lens elements 24b in the projection optical system 24. The projection optical system 24 is also connected to an internal pressure control unit 32 as correction means for changing the pressure in the lens barrel 24a of the projection optical system 24 under the control of the main control system 23. ing.

Next, a configuration for detecting the thermal deformation of the reticle R and correcting the imaging characteristics of the projection optical system 24 based on the detection result will be described in detail. 2 and 3
As shown in the figure, on the reticle substrate Rp of the reticle R,
Periodic patterns 33 as first period generating means are formed so as to be located on both outer sides in the X direction orthogonal to the moving direction (scanning direction) of the reticle R at the time of scanning exposure with respect to the region of the device pattern 17. I have. These periodic patterns 33 are composed of a plurality of rod-shaped marks 33a extending along the X direction and arranged at predetermined intervals along the Y direction.

As shown in FIG. 1 and FIG.
On the back side of 5, a pair of light receivers 34 as cycle detecting means including a CCD camera, a line sensor, and the like are arranged corresponding to each periodic pattern 33 on the reticle R. These light receivers 34 receive an image of the periodic pattern 33 on the reticle R at the time of scanning exposure in a bright field. Then, as shown in FIG. 4A, the light receiver 34 detects a predetermined detection phase period L1 based on the light intensity distribution of each of the received periodic patterns 33, and detects the detection phase period L1.
Is output to the main control system 23.

As shown in FIG. 4 (b), the interferometer 22A generates a predetermined reference phase period signal in order to detect the position of the reticle stage 19 in the scanning direction during scanning exposure. It constitutes two-cycle generating means.
The interferometer 22A is connected to the reticle stage 1
9, at the time of scanning exposure, a reference phase cycle L2 serving as a reference for scanning exposure is detected based on the reference phase cycle signal,
The signal of the reference phase period L2 is output to the main control system 23.

The main control system 23 calculates and detects the phase difference ΔL = L1−L2 based on the detected phase period L1 and the reference phase period L2, and calculates the phase difference ΔL.
Is constantly monitored for changes. The main control system 23
Determines that the reticle R has undergone thermal deformation if the detected phase period L1 fluctuates during this monitoring and the phase difference ΔL changes. Then, the main control system 23 corrects a magnification component of the imaging characteristics so that the imaging characteristics of the projection optical system 24 are maintained in a predetermined state.

In this case, the main control system 23 determines the phase difference Δ
When a change occurs in L, reticle R moves in Y direction, which is the scanning direction.
The magnification correction of the imaging characteristics is performed assuming that the image is uniformly thermally deformed in the direction and the X direction orthogonal thereto.

That is, the main control system 23 controls the driving of the reticle stage driving section 20 and the wafer stage driving section 28 in accordance with the phase difference ΔL, and moves the reticle stage 19 and the wafer stage 27 relative to each other. Change speed. Further, the main control system 23 changes the distance between the lens elements 24b in the projection optical system 24 via the lens distance control unit 31 according to the phase difference ΔL. Further, the main control system 23 controls the phase difference ΔL
, The lens barrel 24a via the internal pressure control unit 32.
Change the pressure inside. With these changes, the magnification component of the imaging characteristic of the projection optical system 24 in the direction orthogonal to the scanning direction of the reticle R and the reticle R is corrected. When changing the relative moving speed of the reticle stage 19 and the wafer stage 27, the main control system 23 controls the exposure amount of the exposure light EL on the wafer W to be always constant without increasing or decreasing. , The output of the light source 11 is controlled.

Next, the operation of the exposure apparatus configured as described above will be described. In this exposure apparatus, the exposure light EL from the light source 11 is incident on the reticle R while the reticle R and the wafer W are moved synchronously. Thereby, the image of the device pattern 17 formed on the reticle R is scanned and exposed on the wafer W via the projection optical system 24. During the scanning exposure, the reticle R absorbs the exposure light EL and is thermally deformed, which may cause a change in the imaging characteristics of the projection optical system 24. However, in this exposure apparatus, the thermal deformation state of the reticle R is constantly monitored, and the imaging characteristics of the projection optical system 24 are corrected according to the monitoring result.

That is, during the scanning exposure, the image of the periodic pattern 33 formed on the reticle R
4, a detection signal having a detection phase period L1 is output based on the light intensity distribution of the image received from the light receiver 34. Further, as the reticle stage 19 on which the reticle R is mounted moves, a signal of a reference phase period L2 serving as a reference for scanning exposure is output from the interferometer 22A.
Then, the main control system 23 calculates the phase difference ΔL based on the detected phase period L1 and the reference phase period L2, and constantly monitors whether the phase difference ΔL has changed.

When the detected phase period L1 fluctuates and the phase difference ΔL changes, the main control system 23 controls the reticle stage 19 according to the phase difference ΔL.
In addition, the moving speed of the wafer stage 27, the distance between the lens elements 24b in the projection optical system 24, and the pressure in the lens barrel 24a are changed. Thereby, the magnification component of the imaging characteristic in the scanning direction of the reticle R and the direction orthogonal thereto is corrected. Therefore, even when the reticle R is thermally deformed, the imaging characteristics of the projection optical system 24 are corrected so as to always maintain a predetermined state, and accurate scanning exposure is performed.

Therefore, according to the present embodiment, the following effects can be obtained. (A) In the exposure apparatus of the present embodiment, the image of the periodic pattern 33 formed on the reticle R is constantly detected by the light receiver 34 during the scanning exposure of the reticle R and the wafer W. A reference phase period L2 serving as a reference for scanning exposure is generated by the interferometer 22A. Then, the main control system 23 detects a phase difference ΔL between the detected phase period L1 based on the light receiving image of the periodic pattern 33 and the reference phase period L2.

Therefore, from the fluctuation of the phase difference ΔL, the fluctuation of the detected phase period L1 based on the periodic pattern 33 on the reticle R can be detected. Then, the thermal deformation state of the reticle R can be constantly monitored as the fluctuation of the detected phase period L1. Therefore,
Due to the thermal deformation of the reticle R, the projection optical system 2
4 can be easily detected as a change in the imaging characteristic.

(B) In the exposure apparatus of the present embodiment, the image of the periodic pattern 33 on the reticle R at the time of scanning exposure is received by the photodetector 34, so that the detection phase period L1
Is detected.

Therefore, the fluctuation of the detection phase period L1 based on the periodic pattern 33 on the reticle R can be easily measured by using the light receiver 34 such as a CCD camera or a line sensor. Therefore, the thermal deformation state of the reticle R can be easily detected.

(C) In the exposure apparatus of the present embodiment, the periodic pattern 33 extends in a direction orthogonal to the scanning direction of the reticle R during scanning exposure, and at a predetermined interval along the scanning direction. It is composed of arranged bar-shaped marks 33a.

For this reason, the detection phase period L1
Can be generated, and the exposure apparatus can be prevented from becoming complicated. (D) In the exposure apparatus of the present embodiment, the periodic pattern 33 on the reticle R is arranged outside the region of the device pattern 17 in a direction orthogonal to the scanning direction.

Therefore, even during the exposure of the device pattern 17 for manufacturing a product wafer, it is possible to constantly monitor the thermal deformation state of the reticle R without hindering the exposure of the device pattern 17 by the periodic pattern 33. it can.

(E) In the exposure apparatus of the present embodiment, a reticle stage 19 on which the reticle R is mounted and moved is provided, and the reference phase period L2 is generated from the interferometer 22A with the movement of the reticle stage 19. It is supposed to be.

Therefore, the reference phase period L2 can be obtained using a reference phase period signal generated for detecting the position of the reticle stage 19 in synchronization with the movement of the reticle stage 19. Accordingly, by calculating the phase difference ΔL of the detected phase period L1 based on the periodic pattern 33 on the reticle R with respect to the reference phase period L2, the thermal deformation state of the reticle R can be achieved without complicating the configuration of the exposure apparatus. Can be accurately and easily detected. Further, when calculating the phase difference ΔL between the detection phase period L1 and the reference phase period L2, there is no possibility of being affected by a synchronization error or the like between the reticle stage 19 and the wafer stage 27, and the thermal deformation of the reticle R can be further reduced. It can be detected accurately.

(F) In the exposure apparatus of this embodiment, the detection phase period L1 based on the period pattern 33 on the reticle R
And the reference phase period L2 generated by the interferometer 22A serving as the reference for scanning exposure is obtained. And
Based on the detection result of the phase difference ΔL, the projection optical system 24
Is corrected.

For this reason, the thermal deformation state of the reticle R is constantly monitored, and based on the monitoring result, the projection optical system 2
4 can be accurately corrected. Therefore,
The above-mentioned image forming characteristics can always be maintained in an optimum state, and the exposure accuracy in the exposure apparatus can be improved.

(G) In the exposure apparatus of the present embodiment, the magnification component of the imaging characteristics of the projection optical system 24 is corrected. For this reason, by correcting the magnification component of the imaging characteristics, the imaging characteristics due to the thermal deformation of the reticle R can be easily corrected.

(H) In the exposure apparatus of this embodiment, the detection phase period L1 based on the period pattern 33 on the reticle R
The relative movement speed between the reticle stage 19 and the wafer stage 27 is changed based on the phase difference ΔL from the reference phase period L2 generated by the interferometer 22A serving as the reference for scanning exposure. Therefore, by correcting the relative movement speed of the two stages 19 and 27, it is possible to easily correct the magnification component of the imaging characteristic in the projection optical system 24 due to the thermal deformation of the reticle R.

(Modification) The above embodiment may be modified as follows. In the above embodiment, the light receiver 34 in the bright field
An image of the periodic pattern 33 on the reticle R at the time of scanning exposure is received to detect the detection phase period L1, but the diffracted light of the laser beam from the periodic pattern 33 is received in a dark field by a predetermined sensor. The detection phase period L
1 may be configured to be detected.

In the above embodiment, the mirror 15
Although the light receiver 34 is arranged on the back side of the optical disk, the light receiver 34 or the sensor may be arranged between the mirror 15 and the reticle R via, for example, a half mirror.

In the above-described embodiment, the relative movement speed of both stages 19 and 27 is changed by correcting the movement speed of both reticle stage 19 and wafer stage 27. The imaging speed of the projection optical system 24 may be corrected by changing either one of the moving speeds 27.

Also in such a case, the same effects as those described in (A) to (H) in the above embodiment can be obtained. In the above embodiment, the reference phase period L2 generated from the interferometer 22A for detecting the position of the reticle stage 19 in the scanning direction is used to detect the detection phase period L1.
, The interferometer 30A for detecting the position of the wafer stage 27 in the scanning direction.
May be used to determine the phase difference ΔL from the detected phase period L1.
In this case, the interferometer 30A constitutes a second phase period generating means.

Also in this case, the same effects as the effects (a) to (d) and (f) to (h) in the above embodiment can be obtained. In the above embodiment, the relative moving speed of the reticle stage 19 and the wafer stage 27 and the projection optical system 24
The image forming characteristics are corrected by changing the lens interval and the internal pressure of the lens. However, the image forming characteristics are corrected by changing at least one of the relative movement speed, the lens interval, and the internal pressure. It may be configured as follows.

Also in this case, effects similar to the effects (a) to (g) in the above embodiment can be obtained. In the above-described embodiment, the light source 11 emits excimer laser light. However, the light source 11 may emit visible light such as g-line, h-line, i-line or the like, or a bright line of ultraviolet light, or metal vapor laser light. , YAG laser light, solid laser light, harmonics of continuous laser light such as fiber laser light, extreme ultraviolet light,
It may generate soft X-rays or the like.

In the above-described embodiment, a specific example of the exposure apparatus having the refraction type projection optical system 24 has been described. However, the present invention is directed to a reflection type projection optical system and an exposure apparatus having a catadioptric type projection optical system. It may be embodied in an apparatus.

In the above embodiment, the reticle R
A specific example of the exposure apparatus having the projection optical system 24 for reducing and projecting the image of the pattern on the wafer W has been described. The present invention may be embodied in an exposure apparatus having an optical system.

In the above-described embodiment, a specific example of the exposure apparatus for manufacturing a semiconductor device has been described.
The present invention may be embodied in an exposure apparatus for manufacturing other microdevices such as a liquid crystal display element, a thin film magnetic head, and an image sensor, or for manufacturing a mask such as a reticle and a photomask.

[0072]

As described above in detail, according to the first aspect of the present invention, the predetermined phase period generated from the mask during the scanning exposure, and the reference phase period serving as the reference for the scanning exposure. With the simple configuration of detecting the phase difference, the thermal deformation state of the mask can be constantly monitored based on the fluctuation of the phase difference. Therefore, it is possible to easily detect a change in the imaging characteristic of the projection optical system due to the thermal deformation of the mask.

According to the second aspect of the present invention, in addition to the effect of the first aspect, a variation of a predetermined phase period generated from the periodic pattern on the mask is easily measured. be able to. Therefore, the thermal deformation state of the mask can be easily detected.

According to the third aspect of the present invention, in addition to the effect of the second aspect of the invention, a predetermined phase period can be generated with a simple configuration, and the apparatus becomes complicated. Can be avoided.

According to the fourth aspect of the present invention, in addition to the effect of the third aspect, the thermal deformation state of the mask is constantly monitored even during the exposure of the device pattern on the mask. can do.

According to the invention as set forth in claim 5 of the present application, in addition to the effects of the invention as set forth in any one of claims 1 to 4, the movement of the mask stage or the substrate stage is accompanied. The thermal deformation state of the mask can be accurately detected based on the phase difference between the reference phase cycle and the predetermined phase cycle.

According to the sixth aspect of the present invention, in addition to the effect of the fifth aspect of the present invention, the configuration using a synchronization signal for detecting the position of the mask stage or the substrate stage is provided. The above-mentioned phase difference can be easily obtained without complicating the above.

According to the seventh aspect of the present invention, in addition to the effects of the first aspect, the thermal deformation of the mask is constantly monitored. The imaging characteristics of the projection optical system can be accurately corrected based on the monitoring result. Therefore, it is possible to always maintain the optimum exposure condition, and it is possible to increase the exposure accuracy in the exposure apparatus.

According to the invention of claim 8 of the present application, in addition to the effects of the invention of any one of claims 5 to 7, a synchronization error between the mask stage and the substrate stage is obtained. By eliminating the effects of the above, the thermal deformation state of the mask can be detected more accurately.

According to the ninth aspect of the present invention, in addition to the effect of the seventh or eighth aspect, correction of the magnification component of the projection optical system reduces thermal deformation of the mask. The resulting imaging characteristics of the projection optical system can be easily corrected.

According to the tenth aspect of the present invention, in addition to the effect of the seventh aspect, at least one of the mask stage and the substrate stage is provided. By correcting the moving speed,
The imaging characteristics of the projection optical system caused by the thermal deformation of the mask can be easily corrected.

According to the eleventh aspect of the present invention, the thermal deformation state of the mask can be constantly monitored,
The imaging characteristics of the projection optical system can be accurately corrected based on the monitoring result, and highly accurate exposure can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a scanning exposure apparatus according to a first embodiment.

FIG. 2 is a perspective view showing a main part of the exposure apparatus of FIG.

FIG. 3 is an enlarged plan view showing the reticle of FIG. 2;

FIG. 4 is a diagram showing a detection signal of a phase cycle on a reticle and a generation signal of a reference phase cycle.

[Explanation of symbols]

11: light source, 17: device pattern, 19: reticle stage as a mask stage, 20: reticle stage drive section constituting a correction means, 22A, 30A: second
Interferometer constituting period generating means, 23 main control system constituting phase difference detecting means, 24 projection optical system, 27 wafer stage as substrate stage, 28 wafer stage driving part constituting correcting means, 31 ... A lens interval control section that constitutes the correction means, 32... An internal pressure control section that constitutes the correction means, 33... A periodic pattern that constitutes the first cycle generation means, 33 a. L1, a detection phase cycle as a predetermined phase cycle, L2, a reference phase cycle, R, a reticle as a mask, W, a wafer as a substrate.

Claims (11)

[Claims] A scanning exposure apparatus configured to scan and expose an image of a pattern formed on the mask onto the substrate while moving the mask and the substrate in synchronization with each other; First cycle generation means for generating a predetermined phase cycle; cycle detection means for detecting the predetermined phase cycle; second cycle generation means for generating a reference phase cycle serving as a reference for the scanning exposure; A scanning exposure apparatus comprising: a phase difference detecting unit that detects a phase difference between a phase cycle and the reference phase cycle. 2. The method according to claim 1, wherein the first period generating means has a periodic pattern formed on the mask, and the period detecting means has a light receiver for receiving an image of the periodic pattern by scanning exposure. The scanning exposure apparatus according to claim 1. 3. The periodic pattern is formed of rod-like marks extending along a direction orthogonal to a moving direction of the mask during the scanning exposure and arranged at predetermined intervals along the moving direction. The scanning exposure apparatus according to claim 2, wherein: 4. The device according to claim 3, wherein the periodic pattern is arranged outside a device pattern region on the mask in a direction orthogonal to a moving direction of the mask.
4. The scanning exposure apparatus according to claim 1. 5. The apparatus according to claim 1, further comprising: a mask stage on which the mask is mounted and moved; and a substrate stage on which the substrate is mounted and moved, wherein the second cycle generating means includes the mask stage or the substrate stage. The scanning exposure apparatus according to any one of claims 1 to 4, wherein the reference phase period is generated with the movement of the scanning exposure apparatus. 6. The apparatus according to claim 1, wherein the second period generating means comprises an interferometer for detecting a position of the mask stage or the substrate stage in a moving direction of the mask or the substrate during the scanning exposure. 6. The scanning exposure apparatus according to 5. 7. A projection optical system for projecting the pattern of the mask onto the substrate, and a correction unit for correcting an imaging characteristic of the projection optical system based on a detection result of the phase difference detection unit. The scanning exposure apparatus according to any one of claims 1 to 6, wherein: 8. The apparatus according to claim 5, wherein said phase difference detecting means detects a phase difference between said predetermined phase cycle and said reference phase cycle generated with movement of said mask stage. Item 8. A scanning exposure apparatus according to any one of Items 7 to 9. 9. The scanning exposure apparatus according to claim 7, wherein the correction unit corrects a magnification component of the imaging characteristics of the projection optical system. 10. The scanning exposure according to claim 7, wherein the correction unit corrects a moving speed of at least one of the mask stage and the substrate stage. apparatus. 11. An exposure method for scanning and exposing an image of a pattern formed on the mask to the substrate via a projection optical system while moving the mask and the substrate in synchronization with each other. Generating a predetermined phase cycle by the first cycle generation means, detecting the predetermined phase cycle by the cycle detection means, and generating a reference phase cycle serving as a reference for the scanning exposure by the second cycle generation means; A phase difference between a predetermined phase period and the reference phase period is detected by a phase difference detection unit, and the imaging characteristic of the projection optical system is corrected based on a detection result of the phase difference detection unit. Exposure method.