JPH05291111A - Alignment equipment - Google Patents

Abstract

PURPOSE:To prevent the decrease of alignment precision when the position of an alignment mark in the exposure area of a projection optical system is changed by alternation of marking and the like. CONSTITUTION:An alignment optical system 19 is arranged so as to be able to move above a reticle 3, and a wafer 6 is irradiated with an alignment beam from the alignment optical system 19, via the reticle 3 and a projection optical system 4. A central processing equipment 12 executes offset correction of measurement results of alignment mark by the alignment optical system 19, according to measurement data of a thermometer 21, an atmospheric pressure meter, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alignment apparatus suitable for application to an alignment system of a projection exposure apparatus having a projection optical system for transferring a pattern formed on a reticle (mask) onto a wafer, In particular, the present invention relates to an alignment apparatus that performs relative alignment between a reticle and a wafer by using alignment light in a wavelength band different from exposure light for transferring a reticle pattern onto a wafer.

[0002]

2. Description of the Related Art When a semiconductor element, a liquid crystal display element, or the like is manufactured by a photolithography technique, a projection exposure apparatus is used which transfers a reticle pattern onto a wafer via a projection optical system. In general, semiconductor devices are manufactured by forming a multi-layered circuit pattern on a wafer, so in the process of transferring a new reticle pattern to a wafer on which a pattern has already been formed, the pattern to be transferred this time has already been formed. It is necessary to accurately align the reticle and the wafer with each other.
Recently, as the fineness of the transferred pattern is further improved, it is an important issue to further improve the alignment accuracy.

Conventionally, the so-called TTR (Through The Reticle) method, which performs alignment between the reticle and the wafer by detecting an alignment mark on the wafer via the reticle and the projection optical system, is high in principle in terms of alignment accuracy. It is expected that accuracy can be achieved. As described above, in the method of detecting the alignment mark on the wafer through the projection optical system, by using the alignment light in the wavelength band different from the exposure light, care is taken so that the resist applied on the wafer is not exposed. ing.

However, when performing alignment based on alignment light in a wavelength band different from the exposure light, the projection optical system causes axial chromatic aberration and lateral chromatic aberration with respect to the alignment light. Therefore, conventionally, an alignment offset, which is a relative difference between the positional relationship between the reticle and the wafer under the exposure light and the positional relationship between the reticle and the wafer under the alignment light, is measured in advance. At the time of actual alignment, the alignment offset is corrected based on the positional relationship between the reticle and the wafer obtained by the alignment light.

In the conventional projection exposure apparatus, the alignment offset is measured at a relatively low frequency when the reticle is replaced or the like. Moreover, once the alignment offset is measured, it is assumed that the alignment offset is constant until the next measurement.
The alignment offset was being corrected.

[0006]

By the way, in the conventional projection exposure apparatus, when transferring a multi-layered circuit pattern onto a wafer, for example, the alignment on the wafer used in transferring the second layer. Considering that the mark may disappear (destroy) due to exposure light irradiation, development, etching, etc., for example, when the third layer is transferred, an alignment mark is newly formed at another position. There is a case where the “change of mark” is performed. When the marks are rewritten in this way, the position of the alignment mark on the wafer within the exposure area of the projection optical system changes slightly. Further, the position of the alignment mark on the wafer also changes when the size of the reticle pattern to be transferred onto the wafer is changed. Therefore, the alignment optical system is also configured to be movable above the reticle.

If the position of the alignment mark on the wafer within the exposure area of the projection optical system changes even a little due to such mark replacement, etc., the amount of alignment offset also changes. In this regard, conventionally, the value of the alignment offset has not been changed even if the position of the alignment mark slightly changes in the exposure area of the projection optical system. However, as the recent demand for alignment accuracy further increases, it is desired to maintain high alignment accuracy even when the position of the alignment mark in the exposure area of the projection optical system changes.

Further, in the conventional projection exposure apparatus, in order to prevent the imaging performance of the projection optical system from changing due to environmental changes such as ambient temperature changes and atmospheric pressure changes, the inside of the projection optical system is prevented. It is configured such that the refractive index of the predetermined lens chamber can be adjusted, or the predetermined distance between the lens groups forming the projection optical system can be adjusted. Then, by changing the refractive index of the predetermined lens chamber or the distance between the predetermined lens groups by the control unit called a lens controller, the image forming characteristic of the projection optical system with respect to the exposure light is maintained in a predetermined state.

However, since the dispersion characteristics of the glass material of the lens constituting the projection optical system are different between the exposure light and the alignment light, even if the image forming characteristics of the projection optical system with respect to the exposure light are completely corrected, they are simultaneously corrected. It is difficult to completely correct the image forming characteristic for the alignment light. Therefore, when the refractive index of the predetermined lens chamber of the projection optical system or the distance between the predetermined lens groups is changed, the alignment light is used for the alignment marks existing at the same position in the exposure area of the projection optical system. There is an inconvenience that an error occurs in the position detection result.

Further, when the exposure light passes through the projection optical system, a part of the exposure energy is accumulated inside the projection optical system to generate a temperature gradient, which is projected according to the amount of the accumulated exposure energy. The image magnification and other factors may change over time. The change in the image forming characteristics in this case is also corrected by the control by the lens controller. However, also in this case, it is difficult to make a complete correction for the alignment light. Therefore, when the exposure is started after the alignment offset is measured once, the actual value of the alignment offset gradually deviates from the measured value, which causes an inconvenience of a positioning error.

In view of the above point, the present invention provides an alignment apparatus in which the alignment accuracy does not decrease even if the position of the alignment mark in the exposure area of the projection optical system changes due to mark replacement or the like. The purpose is to It is another object of the present invention to provide an alignment device in which the alignment accuracy does not deteriorate even if the surrounding environment changes.

[0012]

An alignment apparatus according to the present invention is, for example, as shown in FIG. 1, an illumination optical system for irradiating a mask (3) with exposure light IL from an illumination light source (1) and this mask (3). ) A projection optical system (4) for transferring the pattern formed on the photosensitive substrate (6) under the exposure light.
By illuminating the alignment mark formed on the mask (3) and the alignment mark formed on the photosensitive substrate with the alignment light AL having a wavelength band different from that of the exposure light. , In an alignment device for performing relative alignment between the mask and the photosensitive substrate, the alignment device is movably arranged above the mask (3) and illuminates the alignment mark of the mask with the alignment light AL, and An alignment light-transmitting system (9 to 11) that illuminates the alignment mark of the photosensitive substrate with the alignment light through the mask and the projection optical system, and is movable above the mask in conjunction with the alignment light-transmitting system. The alignment mark is received from the alignment mark of the mask and And a alignment light receiving system (9,10,18) for receiving the alignment light from the alignment mark of the substrate through the projection optical system and the mask thereof.

Furthermore, the present invention relates to a position calculating means (17) for calculating the amount of positional deviation between the mask and the photosensitive substrate based on the light receiving signal from the alignment light receiving system, and the projection optical system (4). Measuring means (21, 22) for measuring environmental conditions, and a predetermined offset correction to the amount of positional deviation between the mask and the photosensitive substrate calculated by the position calculating means (17) according to the measurement results by these measuring means. And a position correction means (12) for performing. In this case, it is desirable that the measuring means (21, 22) measures the amount of exposure energy passing through the projection optical system (4).

[0014]

According to the present invention, the alignment light-transmitting system and the alignment light-receiving system are moved above the mask (3) even when the position of the alignment mark on the photosensitive substrate is changed, for example, by rewriting the mark. As a result, the alignment mark can be accurately detected.
When the position of the alignment mark in the exposure area of the projection optical system is changed, the value of the alignment offset, which is the difference between the positional relationship due to the exposure light and the positional relationship due to the alignment light, also changes. By performing offset correction according to the position of the alignment mark by the correction means (12), the exposure light I can always be accurately measured.
The positional relationship between the mask and the photosensitive substrate under L can be measured. That is, even with an alignment system using non-exposure light, the mask and the photosensitive substrate can always be accurately aligned regardless of the position of the alignment mark.

In order to prevent the imaging characteristics of the projection optical system from changing due to changes in the ambient temperature and atmospheric pressure of the projection optical system and to keep the imaging performance constant, for example, a lens controller is used. The image forming characteristic of the exposure light is maintained in a predetermined state by the control, but even when the alignment offset changes due to this, the measuring means (21, 22)
The position correction means (12) calculates the offset value in accordance with the measurement result according to, and thus the changed alignment offset can be accurately obtained.

Further, when the measuring means (21, 22) measures the amount of exposure energy passing through the projection optical system (4), the amount of exposure energy increases and the projection optical system (4). Even when there is a possibility that the image forming characteristics of the image will change significantly, the image forming characteristics of the exposure light are maintained in a predetermined state by the control of the lens controller, for example, in order to keep the image forming performance constant. The position correction means (12) calculates the offset value with respect to the position detection result of the alignment mark, and the exposure light I
The positional relationship between the mask and the photosensitive substrate under L can be accurately measured.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the alignment apparatus according to the present invention will be described below with reference to the drawings. This example is a TT in a reduction projection type exposure apparatus (stepper) that transfers a reticle pattern onto a wafer by a step-and-repeat method.
The present invention is applied to an R type alignment system. When the TTR type alignment system is used, and especially when the dichroic mirror 2 is used as shown in FIG. 1 of this example, alignment can be performed even during exposure of the wafer.

FIG. 1 shows the overall structure of the exposure apparatus of this embodiment. In FIG. 1, 1 is a light source for exposure light.
The exposure light (i-line, KrF excimer laser light, etc.) IL emitted from the light source 1 is appropriately condensed by an illumination optical system (not shown) through the opening of the shutter 8, and after being reflected by the dichroic mirror 2, The pattern area in which the pattern to be transferred of the reticle 3 is formed is illuminated with a substantially uniform illuminance. The exposure light transmitted through the pattern area of the reticle 3 is focused on the wafer 6 by the reduction projection type projection optical system 4, whereby the pattern of the reticle 3 is transferred onto the wafer 6. Hold this wafer 6 on the wafer stage 7,
A reference mark 5 for aligning the reticle 3 is attached near the wafer 6 on the wafer stage 7.
The wafer stage 7 is an XY stage for positioning the wafer 6 in an XY plane perpendicular to the optical axis of the projection optical system 4, and a Z stage for positioning the wafer 6 in the Z direction parallel to the optical axis of the projection optical system 4. Etc.

Reference numeral 11 denotes a light source for alignment, and alignment light emitted from the light source 11 (illumination light in a wavelength range different from the exposure light IL, such as He-Ne laser light) AL is transmitted through the beam splitter 10. After being bent by the mirror 9 for bending the optical path, the light passes through the dichroic mirror 2 and illuminates a reticle mark which is an alignment mark of the reticle 3. A reticle window is formed in the vicinity of the reticle mark of the reticle 3, and the alignment light passing through the reticle window is guided by the projection optical system 4 onto a wafer mark which is an alignment mark of the wafer 6. The alignment light emitted from the wafer mark to the projection optical system 4 side by reflection or diffraction by the wafer mark returns to the reticle window of the reticle 3 via the projection optical system 4. The alignment light returned to the reticle window and the alignment light from the reticle mark on the reticle 3 enter the beam splitter 10 through the dichroic mirror 2 and the mirror 9 in parallel, and the beam splitter 10
It is reflected by and is incident on the light receiver 18. The photodetector 18 photoelectrically changes the alignment light from the reticle mark and the alignment light from the wafer mark to generate a reticle signal and a wafer signal, and supplies these reticle signal and wafer signal to the alignment processing device 17, respectively. A more specific and detailed configuration of this type of TTR type alignment system is disclosed in, for example, Japanese Patent Laid-Open No. 4-781.
No. 4 publication.

An alignment optical system 19 is composed of the alignment light source 11, the beam splitter 10, the mirror 9 and the light receiver 18, and the alignment optical system 19 is moved above the dichroic mirror 2 in parallel with the reticle 3 to an arbitrary position. It is configured to be able to. Therefore,
As will be described later, the projection optical system 4
Even if the position of the wafer mark on the wafer 6 changes in the exposure area of, the position of the alignment optical system 19 can be changed accordingly. The position of the alignment optical system 19 is controlled by the central processing unit 12 described later.

Reference numeral 12 denotes a central processing unit for controlling the operation of the entire apparatus. The central processing unit 12 controls the opening / closing operation of the shutter 8 via a shutter drive circuit 13. Since the exposure energy per unit time of the exposure light IL passing through the shutter 8 changes depending on the size of the opening of the shutter 8, the central processing unit 12 controls the size of the opening of the shutter 8 and the open time. By doing so, it is possible to irradiate the wafer 6 with the exposure light of the specified amount of energy. The central processing unit 12 also positions the wafer stage 7 via the stage controller 16. In this case, a mirror (not shown) is fixed on the upper surface of the wafer stage 7, and the stage controller 1 is used by this mirror.
By reflecting the laser beam of the laser interferometer built in 6, the coordinates in the plane perpendicular to the optical axis of the projection optical system 4 of the wafer stage 7 are constantly measured.

Reference numeral 14 is a lens controller, 15 is an interferometer wavelength correction unit, 21 is a thermometer, 22 is an atmospheric pressure gauge, and the temperature near the projection optical system 4 measured by the thermometer 21 and the atmospheric pressure gauge 22 are used for measurement. Projection optical system 4
The information on the atmospheric pressure in the vicinity of is supplied to the lens controller 14 and the interferometer wavelength correction unit 15. Projection optical system 4 of this example
Is capable of changing the pressure of a predetermined lens chamber inside, and changing the pressure of the lens chamber to change the refractive index, so that the imaging characteristics (magnification, states of various aberrations, etc.) can be changed. Is configured. And the central processing unit 1
2 is the projection optical system 4 based on the size of the opening of the shutter 8 and the set time set through the shutter drive circuit 13.
The amount of exposure energy passing through is calculated and the amount of exposure energy is notified to the lens controller 14.

The lens controller 14 changes the pressure in a predetermined lens chamber of the projection optical system 4 according to the amount of the exposure energy, the temperature information from the thermometer 21 and the atmospheric pressure information from the atmospheric pressure gauge 22. As a result, the pattern of the reticle 3 is always exposed on the wafer 6 via the projection optical system 4 with the same image forming characteristics. Instead of changing the pressure of a predetermined lens chamber of the projection optical system 4, a predetermined lens group of the lens groups forming the projection optical system 4 may be moved. The exposure surface of the wafer 6 may be set at a position obtained by adding a certain offset to the focus position of the projection optical system 4 obtained by the focusing mechanism (not shown). Other than that, the reticle 3 is slightly moved along the optical axis of the projection optical system 4, or the reticle 3 is slightly tilted with respect to a plane perpendicular to the optical axis of the projection optical system 4, thereby You may make it correct a distortion aberration etc.

Further, the interferometer wavelength correction unit 15 includes the thermometer 2
The wavelength of the laser beam of the laser interferometer is corrected based on the temperature information of 1 and the atmospheric pressure information of the atmospheric pressure gauge 22, and the corrected wavelength is fed back to the stage controller 16 via the central processing unit 12. As a result, the laser interferometer inside the stage controller 16 can accurately measure the coordinates of the wafer stage 7,
The wafer stage 7 is always accurately positioned at the target position regardless of changes in the surrounding environment.

Next, an example of the alignment operation of this embodiment will be described. In this embodiment, the lens controller 1
4 controls so that the image forming characteristics of the projection optical system 4 under the exposure light IL are always the same regardless of changes in surrounding environmental conditions. Changes in imaging characteristics cannot be corrected completely. That is, even if the lens controller 14 controls the image forming characteristics of the projection optical system 4, a control error (control residual) remains with respect to the alignment light AL, and the reticle 3 and the wafer 6 under the exposure light IL. And the alignment relationship, which is the difference between the positional relationship between the reticle 3 and the wafer 6 under the alignment light AL, changes.

This will be described in detail. The exposure apparatus of FIG. 1 is configured so that alignment can be performed even during exposure, and the relative relationship between the reticle 3 and the wafer 6 is constantly changing during exposure according to changes in environmental conditions including changes in the exposure amount. Change. In FIG. 1, the exposure light IL and the alignment light AL are both irradiated onto the reference mark 5, but the exposure light IL and the alignment light AL are separated by Δx in the X direction when passing through the reticle 3. This Δx is an aberration called chromatic aberration of magnification, and the exposure light IL and the alignment light AL when the reference mark 5 is viewed through the projection optical system 4 are shown.
And the position difference of the optical path in the magnification direction. The value of the lateral chromatic aberration Δx temporally changes according to changes in environmental conditions including the exposure amount.

The change amount of the lateral chromatic aberration Δx can be obtained by the central processing unit 12 based on the information from the shutter drive circuit 13 and the lens controller 14. In addition, the reference mark 5 is two-dimensionally moved within the exposure area of the projection optical system 4 to measure the amount of change in the lateral chromatic aberration Δx at each measurement point, whereby the position within the exposure area of the projection optical system 4 is measured. It is possible to obtain the amount of change in the lateral chromatic aberration Δx according to The central processing unit 12 is the alignment processing unit 1
The amount of change in the lateral chromatic aberration Δx is added to the information on the relative position between the reticle 3 and the wafer 6 from 7 and the position information after this addition is used as the position correction amount.
Supply to 6. As a result, the wafer 6 can always be positioned at an accurate position under the exposure light IL.

FIGS. 2 and 3 show states in which the irradiation position of the alignment light AL in FIG. 1 within the exposure area 4I of the projection optical system 4 is observed through the projection optical system 4 and the reticle 3, respectively. 2 and 3, the lens controller 14 controls the imaging characteristics of the projection optical system 4 for the slit-shaped alignment light beams (for example, the alignment light beams X ₁ and X _{2 in} FIG. ₂ ) shown by the solid lines. The previous state,
Slits shown by broken lines (for example, slits XA ₁ and X in FIG. 2)
A ₂ ) shows a state after the lens controller 14 controls the projection optical system 4 so that the imaging characteristics for the exposure light become the same.

Among them, in FIG. 2, X ₁ and X ₂ respectively represent slit-shaped alignment light beams in the X direction (alignment beams), and Y ₁ and Y ₂ respectively represent slit-shaped alignment beams in the Y direction. , These 4
The alignment beam of the book is centered on the reticle 3 (hence,
It is arranged radially from the center of the exposure area 4I).
Then, as a result of the lens controller 14 controlling the projection optical system 4 so that the imaging characteristics regarding the exposure light become constant, the positions of the slit-shaped alignment beams are positions XA ₁ and XA ₂ indicated by broken lines, respectively. And YA ₁ and YA ₂ . For the sake of clarity in FIG. 2, for example, the alignment beam X ₁ and the position XA ₁ (also the alignment beam X ₂ and the position XA ₂ ) are X.
Although they appear to be offset in the directions, they are offset only in the Y direction, which is the non-measurement direction. Similarly, the alignment beam Y ₁ and the position YA ₁ (similarly, the alignment beam Y ₂ and the position YA ₂ ) are deviated only in the X direction which is the non-measurement direction. In this way, when each alignment beam only moves in the non-measurement direction, there is no influence on the alignment.

Next, FIG. 3 shows an example of the case where the position of the alignment mark on the wafer 6 is changed due to the mark reshuffling or the like. In FIG. 3, XB ₁ and XB ₂ are slit-shaped in the X direction. Alignment beam, YB ₁
And YB ₂ respectively indicate slit-shaped alignment beams in the Y direction. When each alignment beam is irradiated onto the wafer 6 through the projection optical system 4, the irradiation position changes depending on the chromatic aberration of magnification in the optical path of the projection optical system 4 through which each beam passes. The chromatic aberration of magnification between the exposure light IL and the alignment light AL is measured by the reference mark 5 on the wafer stage 7, and the reticle 3 is measured based on this measurement result.
By calculating the offset amount of the position detection result of the wafer 6 by the alignment beam with respect to the projected position of the pattern, the irradiation position of the alignment beam on the wafer 6 can be obtained.

After that, when the exposure operation is started, the projection optical system 4
Of the projection optical system 4 changes so that the imaging characteristics of the lens controller 14 such as magnification and distortion under the exposure light IL are constant. Control. Accordingly, the positions of the respective alignment beams in the exposure area 4I are respectively positions XC ₁ and X
Change to C _2, YC ₁ and YC ₂ . In the example of FIG. 3, X
The positional deviation amounts of the alignment beams XB ₁ and XB _{2 for} the directions in the X direction, which is the measurement direction, are ΔX ₁ and Δ, respectively.
X ₂ and the positional deviation amounts of the alignment beams YB ₁ and YB ₂ for the Y direction in the Y direction, which is the measurement direction, are ΔY ₁ and ΔY ₂ , respectively.

These positional deviation amounts are calculated by the central processing unit 1 of FIG.
2 is calculated, and the coordinate value obtained by offset-correcting the target coordinate value of the wafer stage 7 is supplied to the stage controller 16 for accurate positioning under the exposure light IL. be able to. As described above, not only the lens controller 14 corrects the image forming characteristic of the projection optical system 4 according to the ambient temperature fluctuation, the atmospheric pressure fluctuation, and the exposure amount, but also the positional relationship obtained by the alignment beam is used for the exposure light. By the correction, the alignment of the reticle 3 and the wafer 6 under the exposure light IL can be performed with higher accuracy.

In the above embodiment, the correction amount of the alignment offset is determined by the calculation of the central processing unit 12. Alternatively, the position of the alignment beam may be measured at any time using the reference mark 5 or the like, and the alignment operation may be performed based on the measured value. Further, in the above-described embodiments, correction of lateral chromatic aberration is described, but chromatic aberration also includes axial chromatic aberration corresponding to the amount of deviation of the projection optical system 4 with respect to the optical axis direction. This axial chromatic aberration can also be dealt with by similarly obtaining the correction amount by the calculation of the central processing unit 12.

In the TTR type alignment system, depending on the positions of the four alignment marks (wafer marks) around each shot area of the wafer 6, only the relative position and the relative rotation angle between the reticle 3 and the wafer 6 are used. Instead, the relative magnification can be measured. For example, in FIG.
As shown in, the reticle mark on the reticle 3 is AR
1 to AR4, these reticle marks AR1 to A
It is assumed that a wafer mark on the wafer 6 is formed at a position conjugate with R4 under exposure light. However, under the alignment light of the wafer marks on the wafer 6, conjugate images on the reticle 3 are formed, for example, at positions AW1 to AW4 indicated by broken lines, respectively. That is, when observed with alignment light, the wafer mark on the wafer 6 is located at the positions AW1, AW2, AW3 on the reticle 3.
And AW4.

In this case, the reticle marks AR1 to AR4
The wafer mark and the wafer mark are formed, for example, in a cross shape so that the coordinates in a two-dimensional plane parallel to the paper surface of FIG. 4 can be measured. Thereby, the variation of the magnification can be obtained from the interval between the alignment marks facing each other. That is, in FIG. 4, the ratio of the distance between the position AW1 and the position AW3 observed by the alignment light of the wafer mark and the distance between the reticle mark AR1 and the reticle mark AR3 is measured in a predetermined cycle to obtain one direction. A change in the magnification of the projection optical system 4 can be detected. Similarly, position AW2 and position AW observed by the alignment light of the wafer mark
By measuring the ratio of the distance between W4 and the distance between reticle mark AR2 and reticle mark AR4 in a predetermined cycle, it is possible to detect variation in the magnification of projection optical system 4 in another direction.

However, since this is variation in magnification when viewed with alignment light, a correction value for variation in magnification when viewed with exposure light is obtained from the ambient temperature, atmospheric pressure and exposure amount, and this correction value is used. Is added to the variation of the magnification when viewed with the alignment light to calculate the variation of the magnification when viewed with the exposure light. Then, by returning the magnification of the projection optical system 4 to the original value by the lens controller 14, good superposition can be performed. Furthermore, the reference mark 5 in FIG.
It is also possible to detect the fluctuation of the magnification by measuring the position of the alignment beam for the wafer 6 by using, for example, every time the wafer is exchanged or at each exposure.

The exposure apparatus of FIG. 1 measures the position of the alignment mark by using, for example, a two-dimensional CCD camera as the light receiver 18, but the alignment mark detection method is arbitrary. For example, a method of scanning a slit-shaped alignment beam on the alignment mark or a method of using an interference fringe as disclosed in Japanese Patent Laid-Open No. 2-272305 may be used. Further, in the above-described embodiment, the projection optical system including a plurality of lens elements is assumed as the projection optical system 4, but a projection optical system of a mirror projection system or a system combining a reflection system and a refraction system is used. The present invention can be applied to the case where the pressure of a predetermined lens chamber is adjusted or a predetermined optical element is moved.

As described above, the present invention is not limited to the above-described embodiments, and various structures can be adopted without departing from the gist of the present invention.

[0039]

According to the present invention, since the alignment light-transmitting system and the alignment light-receiving system can be moved above the mask in an interlocking manner, the position of the alignment mark on the side of the photosensitive substrate is changed by changing the marks. However, the alignment mark can be accurately detected. Then, the position correction means performs the offset correction of the position detection result for the alignment mark, so that there is an advantage that the alignment accuracy does not decrease even if the position of the alignment mark changes.

Furthermore, since the positional relationship with respect to the exposure light can be obtained by adding an appropriate offset to the position detection result for the alignment mark according to the environmental conditions, even if the environmental conditions such as the ambient temperature change, the alignment can be performed. There is an advantage that accuracy does not decrease. Further, when the measuring means measures the exposure energy passing through the projection optical system, the alignment accuracy does not decrease even if the amount of the exposure energy changes by newly calculating the offset according to the change of the exposure energy. There are advantages.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an exposure apparatus to which an embodiment of an alignment apparatus according to the present invention is applied.

FIG. 2 is a plan view showing an example of positions of alignment marks when observed with alignment light.

FIG. 3 is a plan view showing another example of the position of an alignment mark when observed with alignment light.

FIG. 4 is a plan view showing an example of an alignment mark for detecting a change in magnification.

[Explanation of symbols]

 1 Light Source for Exposure Light 2 Dichroic Mirror 3 Reticle 4 Projection Optical System 5 Reference Mark 6 Wafer 8 Shutter 10 Beam Splitter 11 Light Source for Alignment 12 Central Processing Unit 13 Shutter Drive Circuit 14 Lens Controller 15 Interferometer Wavelength Corrector 16 Stage Controller 17 Alignment processing device 18 Optical receiver 19 Alignment optical system 21 Thermometer 22 Atmospheric pressure meter

Claims (2)

[Claims] 1. An illumination optical system for irradiating a mask with exposure light from an illumination light source, and a projection optical system for transferring a pattern formed on the mask onto a photosensitive substrate under the exposure light. The mask and the photosensitive substrate are provided in the projection exposure apparatus, and the alignment mark formed on the mask and the alignment mark formed on the photosensitive substrate are illuminated with alignment light having a wavelength band different from that of the exposure light, thereby illuminating the mask and the photosensitive substrate. In an alignment apparatus for performing relative alignment of the mask, the alignment mark of the mask is illuminated by the alignment light, and the alignment mark of the photosensitive substrate is masked by the alignment light. And an alignment light-transmitting system that illuminates through the projection optical system, and in conjunction with the alignment light-transmitting system. An alignment light receiving unit that is movably arranged above the mask and receives alignment light from the alignment mark of the mask and receives alignment light from the alignment mark of the photosensitive substrate via the projection optical system and the mask. System, position calculating means for calculating a positional deviation amount between the mask and the photosensitive substrate based on a light receiving signal from the alignment light receiving system, measuring means for measuring environmental conditions relating to the projection optical system, and the measuring means. An alignment apparatus comprising: a position correction unit that performs a predetermined offset correction on the amount of positional deviation between the mask and the photosensitive substrate calculated by the position calculation unit according to the measurement result by 2. The alignment apparatus according to claim 1, wherein the measuring unit measures the amount of exposure energy passing through the projection optical system.