JP3295244B2 - Positioning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning device for adjusting the position of a reticle (mask) or the like provided in a semiconductor manufacturing apparatus or the like.

[0002]

2. Description of the Related Art In recent years, the progress of semiconductor technology has been increasing at an ever-increasing rate, and the fine processing technology has also been remarkably advanced. In particular, in the optical processing technology, which is the main technology of the fine processing technology, the sub-micron region has been advanced beyond the 1MDRAM.

As a means for improving the resolving power of an optical system such as an exposure apparatus, it is generally known to increase the NA (numerical aperture) of the optical system by fixing the wavelength.
However, recently, even at the wavelength of the exposure light, the g-line
The wavelength has been shortened to excimer lasers at 248 nm and 193 nm, and attempts have been made to expand the limit of the resolving power of the light exposure method.

As described above, in an exposure apparatus in which the wavelength of an exposure light source is shortened, a technique for performing high-accuracy alignment of a wafer and a reticle, which is an original of a circuit pattern, in the exposure apparatus with improvement in resolution. Occupies an important position.

As a method of performing alignment between the wafer and the reticle, light that does not expose the resist applied on the wafer (hereinafter referred to as non-exposure light), for example, a wavelength of 633 nm of a He-Ne laser. 2. Description of the Related Art A method of irradiating light onto a (TTL) wafer via a projection lens, detecting an alignment target provided on the wafer, and performing alignment is widely used. However, in this alignment method, since the projection lens has chromatic aberration, it is impossible to observe the wafer and the reticle at the same time. When this method is used, a TTL off-axis form is generally employed.

As described above, in the alignment method in which the TTL off-axis form is adopted, the fluctuation of the baseline (the distance between the shot center at the alignment position and the shot center at the exposure position) greatly increases the accuracy of the alignment. Affect. Therefore, in addition to the TTL off-axis microscope, a TTL on-axis microscope using an exposure wavelength is provided, and the TTL on-axis microscope is used when the reticle is set in the exposure apparatus main body. (2) Positional relationship between reticle and fiducial mark (3) Positional relationship between fiducial mark and TTL off-axis microscope to control baseline fluctuation There has been proposed one that can be easily performed. Hereinafter, an example of a positioning method using a TTL on-axis microscope is described in JP-A-63-32303.

The above-mentioned publication discloses an alignment apparatus that performs alignment by reflecting a plurality of lights having different wavelengths with a reflecting mirror disposed above a reticle surface. In this alignment apparatus, the reflecting mirror is detached from the alignment optical path for each shot on each wafer surface,
When the reflecting mirror is returned after the shot, an error in the returning position of the reflecting mirror generated at the time of the returning is detected and corrected, whereby the reflecting mirror is returned to an accurate position, thereby enabling good alignment.

On the other hand, as a device using a method different from the alignment in the above-described alignment device, there is a positioning device described in Japanese Patent Application Laid-Open No. 4-217260.

The positioning apparatus described in the above publication uses exposure light as measurement light, irradiates the measurement light on a reticle mark on a reticle pre-aligned with a projection exposure apparatus, and reflects the reflected light to the primary. The position of the reticle is detected by detecting the mark position with the pixel position of the image sensor after detecting the mark position with the original image sensor, and then calculating the deviation from the reference pixel set in advance on the image sensor. In this positioning device, a movable light shielding member such as a shutter is provided below the reticle, thereby preventing the wafer from being exposed to measurement light during reticle alignment. Therefore, the reticle can be aligned without retracting the wafer.

Further, there are two types of shutters of the positioning device, one having a high reflectance and the other having a low reflectance on the light irradiation surface side.
The shutter is provided with different types of shutters, the reflectance of the shutter is switched according to the change in the reflectance of the reticle mark, the illumination light illuminating the mark is reflected by the shutter surface, and the mark is illuminated with the reflected light. The best contrast is obtained.

In the positioning device configured as described above, analysis of the waveform of the reticle mark detected by the image sensor is usually performed by binarizing a peak-shaped waveform portion at a predetermined slice level, and analyzing the peak waveform portion. This is performed by a method of finding the center of the pixel position from the rise and fall. When the waveform symmetry of the peak waveform portion with respect to the scanning direction is good, the calculation may be performed by a method of calculating the center of gravity by the integration method.

[0012]

However, each of the above-described conventional positioning devices has the following problems.

In general, reticle marks include a two-layer type having a (chromium oxide layer-chromium layer) configuration and a three-layer type reticle mark having a (chromium oxide layer-chromium layer-chromium oxide layer) configuration. The rates are different. The user can freely select and use these two-layer type and three-layer type reticle marks as needed. When reticle marks having different reflectivities are used as described above, in a conventional positioning apparatus, for example, when the apparatus is set to observe a reticle mark having a high reflectivity, a reticle mark having a low reflectivity is used. When used, the observed image will not be of the best contrast.

Therefore, a reticle is obtained by a method of obtaining the center of the pixel position from the rise and fall of the waveform portion obtained by binarizing the peak waveform portion at a predetermined slice level, or by calculating the center of gravity by an integration method. In Japanese Unexamined Patent Application Publication No. 4-217260, in which the position of a mark is detected, when a reticle on which a reticle mark having a low reflectance is formed is used, a decrease in contrast due to a decrease in the reflectance is caused. As a result, the position detection accuracy is reduced, so that it is difficult to detect the mark position, and there is a problem that accurate positioning cannot be performed.

Similarly, in Japanese Patent Application Laid-Open No. 63-32303, the position detection accuracy is reduced due to a decrease in contrast due to a change in the reflectance of the reticle mark, and accurate positioning is required. There is a problem that it cannot be performed.

[0016] In addition, among those described in JP-A-4-217260, a shutter having a different reflectivity is provided below the reticle, and when a reticle mark having a different reflectivity is used, the reflectivity is reduced. In the case where the reflectivity of the shutter is switched accordingly, the contrast does not decrease even if reticle marks having different reflectivities are used, but there are the following problems.

In the case where the shutter is provided below the reticle, the measurement light illuminated on the reticle mark is reflected by the shutter and transmitted through the reticle mark again. At this time, the reticle mark image generated by the reflected light from the shutter is projected onto the reticle mark in a defocused state. Therefore, in such a system, illuminance non-uniformity occurs in the illumination light for illuminating the reticle mark portion due to the reflected light from the shutter portion. This illuminance unevenness can be reduced by bringing the shutter position as close to the reticle as possible, but usually, since the reticle portion is provided with a drive mechanism for holding and adjusting the position, the shutter is moved in close proximity to the reticle. Cannot be deployed. In this way, the reticle mark image generated by the reflected light from the shutter
In a positioning device in which the illumination light illuminating the reticle mark has uneven illuminance, it is difficult to detect the rising and falling portions of the peak waveform detected due to the uneven illuminance. There is a problem that it cannot be performed.

An object of the present invention is to reduce the detection accuracy even when a reticle on which a reticle mark having a different reflectance is formed is used when aligning a reticle using a mark based on an image sensor or a stage. An object of the present invention is to provide a positioning device that can detect an accurate position of a reticle without causing any trouble.

[0019]

According to the present invention, there is provided a first stage on which a reticle is installed, a second stage on which a wafer is installed, and a first stage between the first stage and the second stage. The projection optical system provided, and the first and second
Moving means for moving the first stage, and the reticle mounted on the first stage is projected and exposed at a predetermined position on a wafer mounted on the second stage via the projection optical system. In the positioning apparatus for adjusting the position of the reticle as described above, each reticle installed on the first stage has an alignment mark having a different reflectivity, and the reticle is positioned on the first stage. Illuminating means for illuminating an alignment mark of a reticle installed on the reticle; a reference reflecting surface provided at a predetermined position on the second stage, the reflecting surface comprising a plurality of reflecting surfaces having different reflectivities; An imaging optical system that forms an image of the alignment mark generated by reflected light reflected by each of the reflection surface and the alignment mark; and an imaging optical system provided on the imaging surface of the imaging optical system. The position shift amount of the reticle set on the first stage is obtained based on the obtained one-dimensional image sensor and the coordinates of the alignment mark detected by the one-dimensional image sensor. Control means for controlling the moving means so that the position of the reticle is an appropriate position based on the reticle, the control means,
When a reticle on which a positioning mark having a high reflectance is formed is used, a reflection surface having a low reflectance of the reference reflecting surface has a conjugate relationship with the positioning mark via the projection optical system. When the reticle on which the alignment mark having a low reflectance is formed is used, the reflection surface having a high reflectance of the reference reflection surface is moved to the position via the projection optical system. The moving means is controlled so as to have a conjugate relationship with the alignment mark.

In this case, reference marks of the same shape are provided on predetermined portions of the respective reflecting surfaces of the reference reflecting surface, and the control means determines the amount of displacement of the reticle by the position adjustment detected by the one-dimensional image sensor. It may be determined from the coordinates of the mark and the coordinates of the reference mark on the reference reflecting surface.

Further, in the above case, the reference reflecting surface is formed by inverting the first reflecting surface having the reflecting portion of a predetermined shape in the transmitting portion, and the transmitting portion and the reflecting portion of the first reflecting surface. When a reticle on which an alignment mark having a high reflectance is formed is used, the first reflecting surface is controlled via a projection optical system. The moving means is controlled so as to have a conjugate relationship with the alignment mark, and when a reticle on which an alignment mark having a low reflectance is formed is used, the second reflection surface is connected via the projection optical system. The moving means is controlled so as to have a conjugate relationship with the alignment mark, and the reticle position shift amount is
The first detected by the one-dimensional image sensor respectively
May be determined based on the coordinates of the reflecting portion of the reflecting surface or the coordinates of the transmitting portion of the second reflecting surface.

[0022]

According to the positioning apparatus of the present invention, a reference reflecting surface composed of a plurality of reflecting surfaces having different reflectivities is provided at a predetermined position on the second stage without providing a shutter below the reticle. . Since each reflecting surface of the reference reflecting surface has a conjugate relationship with an alignment mark formed on the reticle via the projection optical system at each position, in the present invention, the reference reflecting surface Irradiation unevenness does not occur due to reflected light from the light source.

Further, in the present invention, the reflectance of the reference reflecting surface is switched according to the reflectance of the alignment mark of the reticle to be used. That is, when the reflectance of the alignment mark is high, a reference reflective surface having a low reflectance is used, and when the reflectance of the alignment mark is low, a reference reflective surface having a high reflectance is used. Therefore, in the present invention, even if the reflectance of the alignment mark changes, it is possible to accurately detect the rising and falling portions of the peak waveform from the waveform of the alignment mark image detected by the one-dimensional image sensor. As a result, the detection accuracy does not decrease as in the related art.

In another embodiment of the present invention, a reference mark or the like is provided on the reference reflecting surface, and the amount of displacement of the reticle becomes the reference detected by the one-dimensional image sensor. Since it is obtained based on the coordinates of the mark etc., it is necessary to prevent the influence of a slight shift due to a temporal change of each component that occurs in the alignment device that stores the reference coordinates measured at the time of initial setting. It is possible to always obtain a stable reticle position shift amount.

[0025]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram of a reduced projection exposure apparatus equipped with a positioning apparatus according to one embodiment of the present invention.

In FIG. 1, a reticle 1 is provided with a reticle mark 9 at a predetermined position, and is set on a reticle stage 2. The reticle stage 2 is provided with a drive motor 14 for moving the reticle 1 in the XY directions on the stage. A mirror 6 is fixed at a predetermined position on the reticle stage 2.
The amount of movement of the reticle 1 is calculated as a distance from a predetermined reference point by measuring the amount of movement of the reticle 1 with the laser interferometer 15. Note that three sets of drive motors 14 are provided so that the reticle 1 can be independently moved in each of the X direction, the Y direction, and the rotation θ direction, but here, for simplicity of description, The illustration is partially omitted. In addition, the mirror 6 and the laser interferometer 15 also have the reticle 1
Although three sets are installed so as to independently detect the movement amounts of the respective elements, some illustrations are omitted here for the sake of simplicity.

The wafer 4 is placed on the wafer stage 5 so as to face the reticle 1 via the projection lens 3 which is telecentric on both sides or one side. The wafer stage 5 is provided with a drive motor 17 for moving the wafer 4 two-dimensionally along the image plane of the projection lens 3. A mirror 7 is fixed at a predetermined position of the wafer stage 5, and the amount of movement of the mirror 4 is measured as a distance from a predetermined reference point by measuring the amount of movement of the mirror 7 with a laser interferometer 16. Is calculated. Note that two sets of drive motors 17 are provided so that the wafer 4 can be independently moved in two directions of the X direction and the Y direction. Omitted. Similarly, two sets of the mirror 7 and the laser interferometer 16 are provided so as to independently detect the amount of movement of the reticle 1 at each position in the same direction as the drive motor 17, but the description is simplified here. The illustration is partially omitted for the sake of simplicity.

The exposure illumination optical system for exposing the reticle 1 installed as described above to the wafer 4 via the projection lens 3 includes a light source 30, an input lens group 31, an optical integrator 32, mirrors 33 and 35, and a relay. Lens 34,
Main condenser lens 36 and reticle brand 3
7. These components are arranged as follows.

A mirror 11, an input lens group 31, an optical integrator 32, and a mirror 33 are sequentially arranged in the traveling direction of the light beam emitted from the light source 30, and the mirror 33
A relay lens 34, a reticle brand 37, and a mirror 35 are sequentially arranged in the traveling direction of the light beam reflected by the mirror 35, and a main condenser lens 36 and the beam splitter 21 are sequentially arranged in the traveling direction of the light beam reflected by the mirror 35. ing. Note that the beam splitter 21 is
It has a transmittance of 90% and a reflectance of 10% with respect to the wavelength of the light beam emitted from.

In the light beam emitted from the light source 30 of the illumination optical system for exposure configured as described above, the mirror 11
The light beam reflected by is guided to a position detection optical system described below.

The position detecting optical system shares the light source 30 of the exposure illumination optical system. In the position detecting optical system, the light beam reflected by the mirror 11 out of the light beams emitted from the light source 30 is used. The reticle mark 9 provided on the reticle 1 is detected by utilizing the reticle mark 9. The configuration comprises a shutter 12, an objective lens 22, a beam splitter 23, an imaging optical system 24, and a one-dimensional image sensor 25,
Each component is arranged as follows.

A shutter 12, a beam splitter 23, and an objective lens 22 are sequentially arranged in the traveling direction of the light beam reflected by the mirror 11, and the light beam sequentially passing through the respective components is converted into a beam splitter of the illumination optical system for exposure. The reticle mark 9 on the reticle 1 is reflected by the beam splitter 21 to illuminate the reticle mark 9. The beam splitter 23 has a transmittance of 90% and a reflectance of 10% with respect to the wavelength of the light beam emitted from the light source 30, similarly to the beam splitter 21.

In the above configuration, the light beam illuminated on the reticle mark 9 passes through the following first and second optical paths, respectively. That is, the first optical path is projected onto the reference plane 10 via the projection lens 3, reflected by the reference plane 10, transmitted through the reticle 1 again via the projection lens 3, reflected by the beam splitter 21, and The light is incident on the beam splitter 21 via the objective lens 22, and the second optical path is reflected by the reticle mark 9, further reflected by the beam splitter 21, and again passed through the objective lens 22.
It is incident on. An imaging optical system 24 and a one-dimensional image sensor 25 are sequentially arranged in the traveling direction of the light beam reflected by the beam splitter 21.

In the position detecting optical system configured as described above, each reflected light from the reticle mark 9 and the reference surface 10 is formed on the one-dimensional image sensor 25 by the image forming optical system 24, and the image is formed. The system forms an enlarged image of the reticle mark 9 on the image plane.

In this embodiment, the reticle mark 9 and the reference plane 10 have the following structures.

FIG. 2A is a schematic configuration diagram of the reticle mark 9, and FIG. 2B is a schematic configuration diagram of the reference plane 10.

The reticle mark 9 is composed of a transmission part and a reflection part, and the reflection part is in a state where two quadrilateral reflection members are provided at a predetermined interval. On the other hand, the reference plane 10
Are a high reflectance portion 10a and a low reflectance portion 10b
Of the reticle 1 at the respective positions via the projection lens 3 at different positions.
And conjugate relationship. In the present embodiment, the reflecting surface of the reference surface 10 has the portions 10a and 10a in accordance with the reflectance of the reticle mark 9.
b. In addition, each of these parts 10a,
The setting of 10b is performed by control means (not shown)
The control is performed by controlling the control system 18 so that the wafer stage 5 is moved to a position where each of a and 10b is in a conjugate relationship with the reticle mark 9 via the projection lens.

Next, the operation of the positioning device of the present invention using the position detecting optical system configured as described above will be described.

The light beam emitted from the light source 30 is reflected by the mirror 11
And passes through the shutter 12 in the open state. The light beam that has passed through the shutter 12 sequentially passes through the beam splitter 23 and the objective lens 22, is reflected by the beam splitter 21, and is illuminated on the reticle mark 9 on the reticle 1.

The light beam reflected by the reticle mark 9 among the light beams illuminated on the reticle mark 9 enters the beam splitter 21 again, and
The light is reflected by the light source, passes through the objective lens 22, and enters the beam splitter 23. The light beam incident on the beam splitter 23 is reflected by the beam splitter 23, and is reflected by the imaging optical system 24 into a one-dimensional image sensor 25.
Imaged on top.

On the other hand, of the light beam illuminated on the reticle mark 9, the light beam other than the portion reflected by the reticle mark 9 passes through the reticle 1 and is provided on the wafer stage 5 by the projection lens 3. Reference plane 10
Projected above.

The light beam projected on the reference plane 10 is reflected by the reference plane 10 and again enters the beam splitter 23 via the projection lens 3, reticle 1, beam splitter 21 and objective lens 22, respectively. The light beam incident on the beam splitter 23 is reflected by the beam splitter 23 and is imaged on the one-dimensional image sensor 25 by the imaging optical system 24.

As described above, when the reflected light from the reticle mark 9 and the reflected light from the reference plane 10 are respectively imaged on the one-dimensional image sensor 25 by the imaging optical system 24, the one-dimensional image sensor 25 A waveform related to the formed image of the reticle mark 9 is detected as follows.

FIG. 3 is a waveform diagram obtained from the image of the reticle mark 9 formed on the one-dimensional image sensor 25.
(A) shows that the reflectance of the reticle mark 9 is high and the reference surface 10
A portion 10b having a low reflectance is used for the reflection surface of
(B), the reflectance of the reticle mark 9 is low and the reference surface 10
A portion 10b having a low reflectance is used for the reflection surface of
(C), the reflectance of the reticle mark 9 is low and the reference surface 10
In this example, a portion 10a having a high reflectance is used for the reflection surface.

In the one-dimensional image sensor 25, in the case of a reticle having a high reflectance of the reticle mark 9, if the low reflectance portion 10b is used as the reflection surface of the reference surface 10,
A waveform having a clear peak value as shown in FIG.

Here, when a reticle having a low reflectance at the reflection portion of the reticle mark 9 is used, the detected waveform has a lower peak value as shown in FIG. 3B. In this case, the peak value of the waveform becomes low and the peak waveform becomes unclear, so that it is difficult to detect the rise and fall of the peak waveform.

As described above, when the reflectivity of the reflective portion of the reticle mark 9 is reduced, the reflective surface of the reference surface 10 is changed from the low reflective portion 10b to the high reflective portion 10b.
This is changed by moving the wafer stage 5 to a. When the portion 10a having a high reflectance is used as the reflection surface, the waveform detected by the one-dimensional image sensor 25 has a waveform obtained by inverting the waveform of FIG. 3A, as shown in FIG. Will be obtained. As a result, the rise and fall of the peak waveform can be accurately detected from the output waveform.

When the waveform relating to the image of the reticle mark 9 is detected by the one-dimensional image sensor 25 as described above, control means (not shown) derives the reticle mark 9 at each pixel on the one-dimensional image sensor 25 from the detected waveform. Are calculated, and the displacement of the reticle 1 is adjusted from the calculated coordinates and the reference coordinates stored in advance as follows.

The control means (not shown) controls the reticle stage based on the positional deviation of the reticle 1 calculated from the reference coordinates stored in advance and the coordinates of the reticle mark 9 formed on the one-dimensional image sensor 25. The control signal is output to the control system 18 so that the position of the reticle 1 is adjusted by moving the reticle 2 in the X direction, the Y direction, and the rotation θ direction.

When a control signal is input to the control system 18, the drive motor 14 is driven by the control system 18, and the reticle stage 2 is moved in each of the X direction, the Y direction, and the rotation θ direction, and the reticle 1 is moved. Set in the proper position.

In the reduction projection exposure apparatus equipped with the above-described positioning device, the reticle 1 is set at an appropriate position by the positioning device as described above, and then projected onto the wafer 4 by the above-described exposure optical system. Exposure is performed.

The reflecting surface of the reference surface 10 in the positioning apparatus of the embodiment is constituted by two reflecting surfaces having different reflectivities, but is constituted by three or more reflecting surfaces having different reflectivities. May be.

In the positioning of the reticle in the positioning apparatus described above, the reticle position deviation is calculated from the coordinates of the reticle mark image formed on the image sensor and the reference coordinates stored in advance, and the reticle is shifted. Is adjusted, but a fiducial mark is provided on the reference surface 10 and a reticle mark image and a fiducial mark image are formed on an image sensor to obtain the fiducial mark image. Using the coordinates as the reference coordinates, the positional deviation of the reticle can be calculated and adjusted from the reference coordinates and the coordinates of the reticle mark image.

Hereinafter, a case where a fiducial mark is provided on the reference surface 10 of the positioning apparatus of the above embodiment will be described.

A. Example 1 of Fiducial Mark FIG. 4 is a view schematically showing a fiducial mark 50 provided on the reference surface 10 of the positioning device shown in FIG.

The fiducial mark 50 is formed on the reflecting portion 1.
A fiducial mark 50a in which rectangular mark portions 10a2 and 50a3 are provided at predetermined intervals so that their longitudinal directions are orthogonal to each other, and a reflection portion 50b
In one, rectangular mark portions 50b2 and 50b3 are constituted by fiducial marks 50b provided at predetermined intervals so that their longitudinal directions are orthogonal to each other. The fiducial mark 50a and the fiducial mark 50b have the same shape.

In the fiducial mark 50a,
The reflectance of the reflecting portion 50a1 has a value such that the output of the reflected light from the reticle mark 9 has a certain peak value when the reflectance of the reticle mark 9 is high. The reflectance of the mark portions 50a2 and 50a3 is
The value is such that the reflected light from the mark portions 50a2 and 50a3 is substantially the same as the output of the reflected light from the reticle mark 9.

On the other hand, in the fiducial mark 50b, when the reflectance of the reticle mark 9 is low, the output of the reflected light from the reticle mark 9 has a certain peak value when the reflectance of the reticle mark 9 is low. It has a value lower than the reflectance of the reflecting portion 50a1 so as to have. The reflectance of the mark portions 50b2 and 50b3 is
The reflectance of the mark portions 50a2 and 50a3 is lower than the reflectance of the mark portions 50a2 and 50a3 so that the reflected light from the reticle mark 9 has substantially the same output as the reflected light from the reticle mark 9.

In the positioning apparatus of the present embodiment in which the fiducial mark 50 configured as described above is provided on the reference plane 10, the alignment mark is generated on the one-dimensional image sensor 25 by the reflected light from the reference plane 10. The image of the fiducial mark 50 and the image of the reticle mark 9 reflected by the reticle mark 9 are formed, respectively, and the formed image of the reticle mark 9 and the fiducial mark 5 are formed.
The waveform for the 0 image is detected as follows.

FIGS. 5A and 5B are waveform diagrams obtained from the image of the reticle mark 9 and the image of the fiducial mark 50 formed on the one-dimensional image sensor 25. FIG. The fiducial mark 50a is used for the reflecting surface of the reference surface 10, the (b) is the one where the reflectivity of the reticle mark 9 is low and the fiducial mark 50a is used for the reflecting surface of the reference surface 10,
(C), the reflectance of the reticle mark 9 is low and the reference surface 10
The fiducial mark 50b is used for the reflection surface of the above.

In the one-dimensional image sensor 25, if the reflectivity of the reticle mark 9 is high, if the fiducial mark 50a is used as the reflection surface of the reference surface 10, FIG.
A waveform having a clear peak value as shown in FIG.

Here, when a reticle having a low reflectance at the reflecting portion of the reticle mark 9 is used, the detected waveform has a lower peak value as shown in FIG. 5B. In this case, the peak value of the waveform becomes low and the peak waveform becomes unclear, so that it is difficult to detect the rise and fall of the peak waveform.

As described above, when the reflectivity of the reflecting portion of reticle mark 9 decreases, the reflecting surface of reference surface 10 moves wafer stage 5 from fiducial mark 50a to fiducial mark 50b. Will be changed. Fiducial mark 50 as reflective surface
When b is used, in the waveform detected by the one-dimensional image sensor 25, as shown in FIG. 5C, the level value x in the waveform of FIG. 5B decreases, and a peak waveform is obtained. . At this time, as the reflectivity of the mark portion decreases, the peak waveform value of the mark portion in the waveform of FIG. 5B also decreases, and the values of the respective peak waveforms are substantially the same. As a result, the rise and fall of the peak waveform are accurately detected from the output waveform.

As described above, when the one-dimensional image sensor 25 detects a waveform related to the image of the reticle mark 9, control means (not shown) converts the detected waveform into each pixel on the one-dimensional image sensor 25. The coordinates of the image of the reticle mark 9 and the coordinates of the image of the fiducial mark 50 are obtained. The coordinates of the obtained image of the fiducial mark 50 are set as reference coordinates, and the reticle 1 is calculated from the reference coordinates and the coordinates of the image of the reticle mark 9.
Is determined, and the displacement of the reticle 1 is performed on the basis of the determined displacement in the same manner as the adjustment in the positioning apparatus of the above-described embodiment.

In the case where the fiducial mark 50 as described above is used, when the reflectivity of the reticle mark decreases, the reflectivity of the fiducial mark 50 is switched to a lower reflectivity as the reflectivity decreases. Therefore, the peak value of the waveform detected as a result also decreases overall as the reflectivity of the reticle mark decreases. In such a case, the peak value of the detected waveform can be increased as a whole by providing a dimming function for adjusting the amount of detection light.

B. Example 2 of Fiducial Mark FIG. 6 is a diagram of the reflection part of the fiducial mark 50 shown in FIG. 4 and the fiducial mark 60 in which the reflectance of the mark part is changed.

The fiducial mark 60 of the present embodiment
Is a rectangular reflecting portion (mark portion) 6 in the transmitting portion 60a1.
0a2, 60a3 are fiducial marks 60a provided at predetermined intervals such that their longitudinal directions are orthogonal to each other.
Similarly, in the reflecting portion 60b1, rectangular transmission portions (mark portions) 60b2 and 60b3 are constituted by fiducial marks 60b provided at predetermined intervals so that their longitudinal directions are orthogonal to each other. The fiducial mark 60a and the fiducial mark 60b have the same shape with the reflection part and the transmission part inverted.

In the positioning apparatus according to the present embodiment in which the fiducial mark 60 configured as described above is provided on the reference surface 10, the one-dimensional image sensor 25 is generated by the reflected light from the reference surface 10. The image of the fiducial mark 60 and the image of the reticle mark 9 reflected by the reticle mark 9 are respectively formed, and the waveforms of the formed image of the reticle mark 9 and the image of the fiducial mark 50 are as follows. Is detected.

FIGS. 7A and 7B are waveform diagrams obtained from the image of the reticle mark 9 and the image of the fiducial mark 60 formed on the one-dimensional image sensor 25. FIG. The fiducial mark 60a is used for the reflecting surface of the reference surface 10, the (b) is the one where the reflectance of the reticle mark 9 is low, and the fiducial mark 60a is used for the reflecting surface of the reference surface 10,
(C) shows that the reticle mark 9 has a high reflectance and the reference surface 10
The fiducial mark 60b is used for the reflection surface of the above.

In the one-dimensional image sensor 25, if the reflectivity of the reticle mark 9 is high, if the fiducial mark 60a is used as the reflection surface of the reference surface 10, FIG.
A waveform having a clear peak value is detected as shown in FIG.

Here, when a reticle having a low reflectance at the reflecting portion of the reticle mark 9 is used, the detected waveform has a lower peak value of the waveform as shown in FIG. 7B. In this case, the peak value of the waveform becomes low and the peak waveform becomes unclear, so that it is difficult to detect the rise and fall of the peak waveform.

As described above, when the reflectivity of the reflecting portion of reticle mark 9 decreases, the reflecting surface of reference surface 10 moves wafer stage 5 from fiducial mark 60a to fiducial mark 60b. Will be changed. Fiducial mark 60 as reflective surface
When b is used, a waveform detected by the one-dimensional image sensor 25 is obtained as shown in FIG. 7C, which is the inverse of the waveform in FIG. 7A. As a result, the rise and fall of the peak waveform can be accurately detected from the output waveform.

As described above, when the one-dimensional image sensor 25 detects the waveform relating to the image of the reticle mark 9, the control means (not shown) converts the detected waveform into each pixel on the one-dimensional image sensor 25. The coordinates of the image of the reticle mark 9 and the coordinates of the image of the fiducial mark 50 are obtained. The coordinates of the obtained image of the fiducial mark 50 are set as reference coordinates, and the reticle 1 is calculated from the reference coordinates and the coordinates of the image of the reticle mark 9.
Is determined, and the displacement of the reticle 1 is performed on the basis of the determined displacement in the same manner as the adjustment in the positioning apparatus of the above-described embodiment.

[0075]

Since the present invention is configured as described above, it has the following effects.

According to the first aspect of the present invention, since illumination unevenness does not occur due to light reflected from the reference surface, an image with good contrast can be formed on the unified image sensor, and the reticle position detection accuracy can be improved. There is an effect that is improved.

Further, in addition to the above effects, the reflection surface of the reference surface has a low reflectance when the reflectance of the alignment mark is high, and has a low reflectance when the reflectance of the alignment mark is low. Since each is set to a higher value, there is an effect that even if a reticle on which alignment marks having different reflectances are formed is used, the alignment marks can be accurately detected.

According to the second and third aspects of the present invention, the amount of displacement of the reticle is obtained based on the coordinates of a mark or the like serving as a reference of the reference reflecting surface detected by the one-dimensional image sensor. Therefore, as compared with the case where the reference coordinates are provided at the time of the initial setting, there is an effect that a more stable reticle positional deviation amount can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a reduction projection exposure apparatus equipped with a positioning device according to an embodiment of the present invention.

FIG. 2A is a schematic configuration diagram of a reticle mark 9;
FIG. 2B is a schematic configuration diagram of the reference plane 10.

3A and 3B are waveform diagrams obtained from an image of a reticle mark 9 formed on a one-dimensional image sensor 25. FIG. 3A shows a high reflectance of the reticle mark 9 and a low reflectance of the reference surface 10 on the reflection surface. The part 10b is used, (b) is a part where the reflectance of the reticle mark 9 is low, and the part of the reference surface 10 is low reflectance 10b, and (c) is the reflectance of the reticle mark 9 And a portion 10a having a high reflectivity is used as the reflection surface of the reference surface 10.

FIG. 4 is a view schematically showing a fiducial mark 50 provided on a reference surface 10 of the positioning device shown in FIG.

5A and 5B are waveform diagrams obtained from the image of the reticle mark 9 and the image of the fiducial mark 50 formed on the one-dimensional image sensor 25. FIG. 5A shows the fiducial mark 50a on the reflecting surface of the reference surface 10. Are used, and the reflectance of the reticle mark 9 is high, and FIG.
The fiducial mark 50a is used for the reflection surface of
(C) is a state in which the fiducial mark 50b is used for the reflecting surface of the reference surface 10 and the reflectivity of the reticle mark 9 is low.

FIG. 6 is a diagram of a reflection portion of the fiducial mark 50 shown in FIG. 4 and a fiducial mark 60 in which the reflectance of the mark portion is changed.

FIGS. 7A and 7B are waveform diagrams obtained from the image of the reticle mark 9 and the image of the fiducial mark 60 formed on the one-dimensional image sensor 25. FIG. 7A shows the fiducial mark 60a on the reflecting surface of the reference surface 10. Are used, and the reflectance of the reticle mark 9 is high, and FIG.
The fiducial mark 60a is used on the reflection surface of
(C) is a state in which the fiducial mark 60b is used on the reflection surface of the reference surface 10 and the reflectance of the reticle mark 9 is low.

[Explanation of symbols]

 Reference Signs List 1 reticle 2 reticle stage 3 projection lens 4 wafer 5 wafer stage 6, 7, 33, 35 mirror 9 reticle mark 10 reference plane 14, 17 drive motor 15, 16 laser interferometer 18 control systems 21, 23 beam splitter 22 objective lens 24 Imaging optical system 25 One-dimensional image sensor 30 Light source 31 Input lens group 32 Optical integrator 34 Relay lens 36 Main condenser lens 37 Reticle brand

Claims (3)

(57) [Claims] A first stage on which a reticle is installed, a second stage on which a wafer is installed, a projection optical system provided between the first stage and the second stage, Moving means for moving the first and second stages, wherein a reticle mounted on the first stage is mounted on a wafer mounted on the second stage via the projection optical system. In a positioning device for adjusting the position of the reticle so that the position is projected and exposed, each reticle installed on the first stage includes:
Illuminating means for illuminating alignment marks of a reticle installed on the first stage, wherein alignment marks having different reflectivities are formed, and provided at a predetermined position on the second stage. Forming a reference reflecting surface including a plurality of reflecting surfaces having different reflectivities, and an image of the alignment mark generated by reflected light reflected by each of the reference reflecting surface and the alignment mark. An imaging optical system; a one-dimensional image sensor provided on an imaging surface of the imaging optical system; and a first stage mounted on the first stage based on coordinates of an alignment mark detected by the one-dimensional image sensor. Control means for calculating the position shift amount of the reticle obtained, and controlling the moving means so that the position of the reticle becomes an appropriate position based on the obtained position shift amount. The control means, when a reticle on which a positioning mark having a high reflectance is formed is used, a reflection surface having a low reflectance of the reference reflecting surface is aligned with the positioning mark via the projection optical system. When the reticle on which the alignment mark having a low reflectance is formed is used by controlling the moving means so as to have a conjugate relationship, the reflection surface having a high reflectance of the reference reflection surface is formed by the projection optical system. A positioning device that controls the moving means so as to have a conjugate relationship with the positioning mark via the control unit. 2. The positioning device according to claim 1, wherein the reference reflecting surface is provided with a reference mark having the same shape on a predetermined portion of each of the reflecting surfaces. A positioning apparatus, wherein a position shift amount of a reticle is obtained from coordinates of a positioning mark detected by a sensor and coordinates of a reference mark on the reference reflecting surface. 3. The positioning device according to claim 1, wherein the reference reflecting surface includes a first reflecting surface provided with a reflecting portion having a predetermined shape in the transmitting portion, and a transmitting portion of the first reflecting surface. And a second reflecting surface having an inverted reflecting portion. When a reticle on which an alignment mark having high reflectivity is formed is used, the first reflecting surface is a projection optical system. Controlling the moving means so as to have a conjugate relationship with the positioning mark via, when a reticle on which a positioning mark with a low reflectance is formed is used,
The moving means is controlled so that the second reflection surface has a conjugate relationship with the alignment mark via the projection optical system, and the position shift amount of the reticle is detected by the one-dimensional image sensor. Wherein the coordinates of the reflection portion of the reflection surface or the coordinates of the transmission portion of the second reflection surface are determined as a reference.