JPH05109604A - Inclination-angle detector of optical axis of synchrotron radiation and axis of aligner - Google Patents

Abstract

PURPOSE:To detect in which direction and at which angle the optical axis of an SR beam and the axis of an aligner are inclined. CONSTITUTION:Two or four photodetectors 10, 11 are attached to a wafer mounting face 5 at an aligner 3; a light-shielding plate or a plurality of pinholes 6 to 9 are arranged on the wafer mounting face; an SR beam 1 reaches the photodetectors through the circumference of the light-shielding plate or through the pinholes; the incident light quantity of an angle detector is changed by tilting the optical axis of the SR beam. Thereby, it is possible to obtain an effect that the position of an aligner with reference to the optical axis of the SR beam can be corrected with good accuracy and easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tilt angle detector (hereinafter referred to as SR light angle detector) of an optical axis of synchrotron radiation (hereinafter referred to as SR light) and an axis of an exposure apparatus, and particularly S
In an X-ray exposure apparatus using X-rays in R light, an optical axis of synchrotron radiation light for detecting an angle of inclination between an optical axis of the synchrotron radiation light and a vertical line of a wafer mounting surface of the X-ray exposure apparatus. The present invention relates to a tilt angle detector of an axis of an exposure apparatus.

[0002]

2. Description of the Related Art Generally, an X-ray exposure apparatus that exposes a wafer with X-rays contained in SR light aligns a pattern formed on the wafer with a pattern of an X-ray mask and detects a positional deviation by an alignment detector. The position is corrected on the wafer mounting surface, and X-ray irradiation is performed for exposure. The wafer and the X-ray mask are held at intervals of several tens of μm and adjusted so as to be parallel to each other. Therefore, if the perpendicular of the wafer mounting surface of the exposure apparatus is inclined with respect to the optical axis of the SR light, the pattern transferred to the wafer will be displaced. In order to transfer a fine pattern of 0.25 μm or less, the positional deviation must be corrected with an accuracy of 0.1 μm or less, and when the inclination angle is set, it must be detected and corrected at an angle of 2.5 mrad or less. .

When SR light is used in an X-ray exposure apparatus, it is usually used in a vacuum state, but for efficiency, it is taken out into the atmosphere through a beryllium window immediately before the mask. However, since the beryllium window hardly transmits visible light, it is difficult to detect the X-ray optical axis in the atmosphere.

Therefore, in the conventional detection of the SR optical axis and the axial tilt angle of the exposure apparatus, the exposure apparatus is aligned so that the wafer mounting surface is parallel to the end surface of the beam line without using the apparatus. After that, the X-ray mask was aligned with the resist-coated wafer, and the deviation of the perpendicular of the wafer mounting surface to the optical axis of the SR light was detected by the shape and position of the transferred pattern. However, since the SR light and the beam line are not accurately aligned with each other and are detected with an alignment error peculiar to the exposure apparatus, even if the posture of the exposure apparatus is corrected according to the detection result, accurate correction is not possible. Therefore, it was necessary to repeat the detection and correction of the inclination by the trial exposure described above several times to gradually improve the accuracy.

Further, conventionally, a device for detecting the SR light and the axis shift between the exposure device shown in FIG. 9 has been used. The apparatus shown in FIG. 9 is provided on the wafer mounting surface 5 of the stage 4 of the exposure apparatus 3 installed at the tip of the beam line 2 for irradiating the SR light 1, and is arranged on the vertical line of the wafer mounting surface 5, respectively. 1 pinhole 13 and 2nd pinhole 14, 1st
2 and the photodetector 12 installed on the wafer mounting surface 5 on a perpendicular line passing through the second pinhole 14. (Japanese Patent Application No. 01-122440) The method for detecting the axis deviation in the apparatus shown in FIG.
The SR light 1 emitted at an angle to the perpendicular of
Since it is difficult to pass through the second pinhole 7 even if it passes through the pinhole 6, the amount of light incident on the photodetector 12 becomes small and the output of the photodetector 12 becomes small. When the perpendicular of the wafer mounting surface 5 and the optical axis of the SR light 1 are parallel, the photodetector 12
Since the amount of light incident on is maximum and the output of the photodetector 12 is maximum, it can be seen that the perpendicular of the wafer mounting surface 5 and the optical axis of the SR light 1 are parallel.

[0006]

As described above, the conventional resist-coated wafer is aligned with the X-ray mask, trial exposure is performed, and the optical axis of SR light from the transferred pattern and the exposure apparatus. The method of indirectly detecting the inclination angle of the axis has a drawback in that the accuracy is not good and it takes time and labor.

Further, since the conventional optical axis of SR light provided with the pinhole and the axis deviation detection device of the exposure device make the judgment only by the magnitude of the output of one photodetector, the vertical (left and right) However, it is difficult to correct the position of the exposure apparatus because it is not known at which angle in which direction the axis is displaced.

[0008]

An inclination angle detector of the optical axis of SR light and the axis of an exposure apparatus of the present invention is mounted on a mounting surface of a wafer exposed by synchrotron radiation light.
And a second photodetector, first and second pinholes that are provided on a first straight line that passes through the first photodetector and is inclined with respect to a normal line of the wafer mounting surface, and the first photodetector and the second photodetector. The first line with respect to the perpendicular of the wafer mounting surface through the second photodetector.
Of the first and second pinholes arranged directly above the second and third pinholes symmetrical to each other, the optical axis of the synchrotron radiation being perpendicular to the wafer mounting surface. The light detectors are characterized in that the incident light amounts are equal. The tilt angle detectors of the optical axis of the SR light and the axis of the exposure apparatus of the present invention are not aligned in a straight line attached to the attachment surface of the wafer exposed by the synchrotron radiation.
A fourth photodetector, first and second pinholes provided on a first straight line that passes through the first photodetector and is inclined with respect to a perpendicular to the wafer mounting surface, and the second photodetector. Passing through the photodetector, and third and fourth pinholes arranged on a second straight line symmetric to the first straight line with respect to a vertical line of the wafer mounting surface, and passing through the third photodetector. 5th provided on the 1st straight line inclined with respect to the perpendicular of the wafer mounting surface
And a sixth pinhole, and seventh and eighth pinholes which are arranged on a fourth straight line which passes through the fourth photodetector and is symmetrical with respect to a perpendicular of the wafer mounting surface to the third straight line. The amount of light incident on the first and second photodetectors is equal when the optical axis of the synchrotron radiation is perpendicular to the wafer mounting surface, and the amount of light incident on the third and fourth photodetectors is the same. Are equal to each other.

The tilt angle detector of the optical axis of the SR light and the axis of the exposure apparatus of the present invention is the same as the first and second photodetectors mounted on the mounting surface of the wafer exposed by the synchrotron radiation. And a light-shielding plate which is provided on the wafer mounting surface and is spaced apart from each other, and which shields the synchrotron radiation light in a symmetrical shape with respect to a plane forming a center between the first and second photodetectors. When the optical axis of the tron radiation is perpendicular to the wafer mounting surface, the amounts of light incident on the first and second photodetectors are equal.

The tilt angle detectors of the optical axis of the SR light and the axis of the exposure apparatus of the present invention are mounted on the mounting surface of the wafer exposed by the synchrotron radiation and are located at a center point provided on the mounting surface of the wafer. First and second photodetectors of equal shape at equal distances, and third and fourth photodetectors of equal shape at equal distances from the center point in different directions from the first and second photodetectors And a plane that is provided on the wafer mounting surface at a distance from each other and forms a center between the second first and second photodetectors, and a plane that forms a center between the third and fourth photodetectors. A light-shielding plate for blocking the synchrotron radiation in a shape, wherein the amounts of light incident on the first and second photodetectors are equal to each other when the optical axis of the synchrotron radiation is perpendicular to the wafer mounting surface. Third and fourth light Amount of light incident on the output device is equal to or equal to each other.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 and FIG. 2 are sectional views of an embodiment of a tilt angle detector of the optical axis of SR light and the axis of the exposure apparatus of the present invention.

The apparatus shown in FIG. 1 has a stage 4 of an exposure apparatus 3 installed at the tip of a beam line 2 for irradiating SR light 1.
Of the first pinhole 6 and the second pinhole 7 which are provided on the wafer mounting surface 5 and are arranged on a first straight line having an angle with respect to the vertical line on the wafer mounting surface 5. First photodetector 10 installed on the wafer mounting surface 5 on the straight line
And a third pinhole 8 and a fourth pinhole 9 arranged on a second straight line which is symmetrical to the first straight line with respect to the perpendicular of the wafer mounting surface 5, and the wafer mounting on the second straight line. And a second photodetector 11 installed on the surface 5.

Next, a method of detecting the SR light and the axis deviation of the exposure apparatus according to this embodiment will be described.

This device is mounted on the wafer mounting surface 5 S
When the optical axis of the R light 1 is shaken up and down, the output 21 of the first photodetector 10 and the output 22 of the second photodetector 11 as shown in FIG.
Is obtained. The difference between the two outputs 21 and 22 is shown in FIG.

Here, when the SR light 1 is irradiated at a certain angle (an angle close to the above-mentioned first straight line) with respect to the vertical line of the wafer mounting surface 5 as shown in FIG. 1, the first photodetector 10 Is S
Since the R light 1 hardly enters, the first output 21 becomes small. This is designated as point a in FIG. However, since the amount of SR light 1 incident on the second photodetector 11 is large, the second output 22 is large. This is designated as point b in FIG.
In this case, if the second output 22 is subtracted from the first output 21, a negative value is calculated. This is represented by point c in FIG. The sign of the point C indicates the direction of the inclination of the optical axis of the SR light 1, and the value indicates the angle.

Further, when the optical axis of the SR light 1 and the perpendicular of the wafer mounting surface 5 are parallel as shown in FIG. 2, the SR light incident on the first photodetector 10 and the second photodetector 11 is incident. The light amount of 1 becomes the same amount, and the first photodetector 10 and the second photodetector 11
The outputs 21 and 22 of 1 match. This is designated as point d in FIG. In this case, from the value of the first output 21 to the second output 22
It becomes 0 when the value of is subtracted. This is represented by point e in FIG. That is, the difference between the first output 21 and the second output 22 is 0.
It can be seen that the optical axis of the SR light 1 and the perpendicular of the wafer mounting surface 5 are parallel to each other.

However, in the actual apparatus, the SR light 1 is always radiated in a fixed direction, and the correction is performed on the wafer mounting surface 5.

FIG. 5 is a perspective view showing a part of an embodiment of a tilt angle detector of the SR light optical axis and the exposure apparatus axis according to the present invention.

The SR light inclination angle detector shown in FIG. 5 is composed of a pedestal 58, a first photodetector 51 and a second photodetector 51 arranged on the pedestal 58 at equal distances in the vertical and horizontal directions from the center of the pedestal 58. Of the second photodetector 52, the third photodetector 53, the fourth photodetector 54, and the first photodetector 51, the second photodetector 51 perpendicular to the pedestal 58.
Outer photodetector 52, the third photodetector 53 and the fourth photodetector 54, and a pedestal 58 at the tip of the outer frame 57.
It is surrounded by a beryllium thin film 56 fitted in parallel with, a beryllium shading plate 5 centered on a vertical line passing through the center of a pedestal 58 arranged on the thin film 56, a pedestal 58, an outer frame 57 and a beryllium thin film 56. And a helium gas 59 filled in the enclosed space. The light-shielding plate 5 is a square having each side horizontal or vertical, and has a size such that when viewed from the front of the pedestal 58, a part of each of the first to fourth photodetectors 51 to 54 can be seen.

FIG. 6 is a sectional view showing a state in which the exposure apparatus of the embodiment shown in FIG. 5 is mounted. This SR light angle detector is mounted on the wafer mounting surface 5 of the stage 4 of the exposure apparatus 3 and installed at the tip of the beam line 2. When the optical axis of the SR light 1 is swung from the bottom to the top, the first output 31 from the first photodetector 51 and the second
Two outputs of the second output 32 from the photodetector 2 of Then, the direction of inclination can be detected from the sign of the value obtained by subtracting the second output 32 from the first output 31, and the angle can be detected from the value. FIG. 8 shows the value of this difference in a graph.

For example, when the SI light 1 is irradiated from above at a certain angle as shown in FIG. 7, the SR light 21 incident on the first photodetector 51 has a large amount of light, so that the first output 31 is growing. When this is represented on FIG. 7, it is point f. On the contrary, since the SR light 1 hardly enters the second photodetector 52, the second output 32 becomes small. When this is represented on FIG. 7, it is point g. Then, a positive value is calculated by taking the difference between the first output 31 and the second output 32.
This is represented by point h in FIG. The inclination direction can be detected from the sign at this time, and the angle can be detected from the value. The left and right can be detected similarly.

When the SR light 1 and the wafer mounting surface 5 are perpendicular to each other, the SR light 1 incident on all the photodetectors 51 to 54 has the same light amount. When this is shown in FIG. 7, it is point j. Then, the first output 31 and the second output 32
It becomes 0 when the difference of is taken. This is represented by k points in FIG. That is, the difference between the first output 31 and the second output 32 is 0.
Therefore, it can be detected that the SR light 21 and the wafer mounting surface 11 are vertical.

In the embodiment shown in FIG. 1, in addition to the first to fourth pinholes 6 to 9 on the vertical plane, a plurality of pinholes and a wafer mounting surface are similarly provided on the horizontal water surface. If a photodetector is provided, the horizontal tilt angle as well as the vertical tilt angle of the SR light can be detected. Even when only the first and second photodetectors 51 and 52 or only the third and fourth photodetectors 53 and 54 are provided in the embodiment shown in FIG. 5, the vertical tilt angle of SR light or Only the left and right tilt angles can be detected.

[0025]

According to the SR light angle detector of the present invention, by calculating the difference between the output values of the photodetectors located at symmetrical positions, it is possible to determine in which direction the SR light is directed with respect to the vertical line of the wafer mounting surface. Since it is possible to detect the angle of inclination, it is possible to improve the accuracy of correcting the position of the exposure apparatus and to facilitate the correction.

[Brief description of drawings]

FIG. 1 is a side sectional view of an embodiment of the present invention.

FIG. 2 shows the SR light 1 of the embodiment shown in FIG.
It is a side sectional view at the time of being perpendicular to 1.

FIG. 3 shows first and second photodetectors 10 and 11 in FIG.
It is a figure which shows the output of.

FIG. 4 is a diagram showing a difference between outputs 21 and 22 in FIG.

FIG. 5 is a perspective view of another embodiment of the present invention.

FIG. 6 is a side sectional view of a state in which the exposure apparatus 3 of the embodiment shown in FIG. 5 is attached.

FIG. 7 is a diagram showing first and second photodetectors 51 and 52 in FIG.
It is a figure which shows the output of.

8 is a diagram showing a difference between outputs 31 and 32 in FIG.

FIG. 9 is a side view of a conventional tilt angle detector for the optical axis of SR light and the axis of the exposure apparatus.

[Explanation of symbols]

 1 SR Light, 2 Beamline 3 Exposure Device 4 Stage 5 Wafer Mounting Surface 6 First Pinhole 7 Second Pinhole 8 Third Pinhole 9 Fourth Pinhole 10 First Photodetector 11 Second Photodetector 12 photodetector 13 first pinhole 14 second pinhole 51 first photodetector 52 second photodetector 53 third photodetector 54 fourth photodetector 55 light shielding Plate 56 Thin film of beryllium 57 Outer frame 58 Pedestal 59 Helium gas

Claims (4)

[Claims] 1. A first and a second photodetector attached to a mounting surface of a wafer exposed by synchrotron radiation, and a perpendicular line of the wafer mounting surface passing through the first photodetector. A first and a second pinhole provided on the inclined first straight line, and a second pinhole passing through the second photodetector and symmetric with the first straight line with respect to a vertical line of the wafer mounting surface.
And third and fourth pinholes disposed directly above the optical axis of the synchrotron radiation, and the amount of light incident on the first and second photodetectors when the optical axis of the synchrotron radiation is perpendicular to the wafer mounting surface. A tilt angle detector between the optical axis of the synchrotron radiation and the axis of the exposure apparatus, characterized in that 2. A first to a fourth photodetector, which are mounted on a mounting surface of a wafer exposed by synchrotron radiation and are not aligned, and the wafer mounting which passes through the first photodetector. The first and second pinholes provided on the first straight line inclined with respect to the vertical line of the surface, and the first line with respect to the vertical line of the wafer mounting surface that passes through the second photodetector.
The third and fourth pinholes arranged on a second straight line which is symmetrical to the straight line of the above, and on the first straight line which passes through the third photodetector and is inclined with respect to the perpendicular to the wafer mounting surface. The fifth and sixth pinholes provided and the seventh and sixth pinholes arranged on a fourth straight line which passes through the fourth photodetector and is symmetric with respect to the perpendicular of the wafer mounting surface. 8 pinholes, and when the optical axis of the synchrotron radiation is perpendicular to the wafer mounting surface, the amounts of light incident on the first and second photodetectors are equal and the third and fourth photodetections are performed. An inclination angle detector between the optical axis of the synchrotron radiation and the axis of the exposure apparatus, characterized in that the amounts of light incident on the vessel are equal. 3. A first and a second photodetector of the same shape mounted on a mounting surface of a wafer exposed by synchrotron radiation, and the first and second photodetectors provided on the wafer mounting surface at a distance from each other. A light-shielding plate that shields the synchrotron radiation in a symmetrical shape with respect to a plane that is the center between the second photodetectors, and the first axis when the optical axis of the synchrotron radiation is perpendicular to the wafer mounting surface. And an inclination angle detector between the optical axis of the synchrotron radiation and the axis of the exposure apparatus, wherein the amounts of light incident on the second photodetector are equal. 4. A first and a second photodetector, which are mounted on a mounting surface of a wafer exposed by synchrotron radiation and are equidistant from a center point provided on the mounting surface of the wafer, and the first and second photodetectors. Third and fourth photodetectors having the same shape and equidistant from each other in the different direction from the first and second photodetectors, and the second first and second photodetectors provided on the wafer mounting surface at a distance from each other. And a light-shielding plate for blocking the synchrotron radiation in a symmetrical shape with respect to a plane forming a center between the second photodetector and a plane forming a center of the third and fourth photodetectors. When the optical axis of the emitted light is perpendicular to the wafer mounting surface, the amounts of light incident on the first and second photodetectors are equal to each other.
And an inclination angle detector between the optical axis of the synchrotron radiation and the axis of the exposure apparatus, wherein the amounts of light incident on the fourth photodetector are equal to each other.