JP3143514B2 - Surface position detecting apparatus and exposure apparatus having the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for detecting a focus position used in, for example, a semiconductor projection exposure apparatus for transferring a circuit pattern onto a wafer.

[0002]

2. Description of the Related Art In recent years, as a focus position detection mechanism of a semiconductor exposure apparatus, the NA of a projection exposure optical system has been increased, and the allowable focal depth of pattern transfer tends to be further reduced. Therefore, the mainstream of the focus position detection mechanism is a system configuration that detects the inclination of the exposure area on the wafer on which pattern transfer is performed and adjusts the focus so that the entire exposure area is focused.

A conventional focal plane position detecting mechanism is provided with a plurality of air sensors at the periphery of an exposure area on a wafer, and calculates and adjusts the inclination and height position of the exposure area based on height information around the exposure area. The method was common. As another method, as described in Japanese Patent Publication No. 2-10361, the height position of the center of the exposure area is detected and adjusted by an oblique incidence height position detecting optical system. There is known an example of calculating and adjusting a tilt in an exposure region by another tilt detection optical system (collimator) for oblique incidence.

However, the above-mentioned conventional example has various disadvantages. Therefore, the applicant of the present application has previously filed Japanese Patent Application No. 3-157822.
In the above issue, an excellent surface position detecting device that solves these disadvantages was proposed.

The present invention is a further improvement of the proposed device. The object of the present invention is to provide a surface position detecting device in which the measurement points are made variable according to conditions to improve the accuracy of detecting the surface position. And an exposure apparatus having the same.

[0006]

According to the present invention, there is provided a surface position detecting apparatus for irradiating a plurality of different measurement positions on a surface to be inspected with a light beam from an oblique direction. Means for receiving reflected light and obtaining position information of the test surface based on a detection signal at each measurement position. A plurality of one-dimensional array sensors for receiving the reflected light. Wherein one of the reflected lights from a plurality of different measurement points is simultaneously detected by the same one-dimensional array sensor.

[0007]

1 and 2 are side views of an embodiment of the present invention. FIG. 1 is a structural view showing a light irradiation means A for forming a plurality of measurement points in a test area on a wafer. FIG. 2 is a configuration diagram showing a photoelectric conversion unit C and a projection unit B for detecting each light beam reflected at a plurality of measurement point positions in a test area on a wafer. This embodiment shows an example in which the surface position detecting device is mounted on a reduction projection exposure device.

In both figures, reference numeral 1 denotes a reduction projection lens system, a reticle stage (not shown) is provided above the projection lens system 1, and an exposure illumination system (not shown) is provided above the reticle stage. I have. Ax is the projection lens system 1
2 shows the optical axis. Reference numeral 2 denotes a semiconductor wafer, which is mounted on a wafer stage 3 by being suction-fixed. The wafer stage 3 is movable and moves the wafer 2 to the optical axis Ax of the projection lens system 1.
In the direction (z direction) and the direction (x, y directions) orthogonal to the optical axis Ax, and a plane (XY) orthogonal to the optical axis Ax.
The surface of the wafer 2 can be inclined with respect to the plane.
The movement control and tilt control of the wafer stage 3 in the x, y, and z directions are performed by the stage control device 4. The circuit pattern is transferred onto the wafer 2 by illuminating the circuit pattern of the reticle mounted on the reticle stage with uniform illuminance with light from the exposure illumination system, and the projection lens system 1 converts the image of the reticle circuit pattern into a wafer. 2 is carried out by reducing the projection. At this time, the surface of the wafer 2 must be positioned on a plane conjugate with the plane on which the reticle circuit pattern is located with respect to the projection lens system 1. For controlling the position of the surface of the wafer 2 as described above, a surface position detecting device including a light irradiation unit A, a projection unit B, and a photoelectric conversion unit C is provided.

The light irradiation means A includes a light source 5, a collimator lens 6, a mirror 7, an optical system block 8, a lens system 9, and a mirror 10. The light source 5 is composed of a lamp that emits light of a plurality of different wavelengths. The collimator lens 6 converts the light from the light source 5 into a parallel light beam having a substantially uniform cross-sectional intensity distribution. Then, it is directed to the optical system block 8. The optical system block 8 is formed by laminating a pair of prisms such that their slopes face each other, and a slit 80 is formed on the lamination surface. This slit 8
0 has pinholes 81, 82, 83, 84, 85, 8
6, 87, 88 and 89 are provided.

With respect to the lens system 9, pinholes 81 to 8
9 and the plane including the slit 80 and the wafer 2
The plane including the surface of satisfies the condition of Scheimpflug,
The imaging magnification of the pinholes 81 to 89 by the lens system 9 is β
_{9 (81) to} β _{9 (89)} , β _{9 (81)} ≠ β _{9 (82)} ≠ β
_{9 (83)} ≠ β _{9 (84)} ≠ β _{9 (85)} ≠ β _{9 (86)} ≠ β _{9 (87)} ≠ β
_{9 (88)} ≠ β9 ₍₈₉₎ , and the imaging magnification of the pinhole image closer to the lens system 9 is larger. That is, β _{9 (81)}
<Β _{9 (82)} <β _{9 (83)} <β _{9 (84)} <β _{9 (85)} <β _{9 (86)}
<Β _{9 (87)} <β _{9 (88)} <β _{9 (89)} . Therefore, in this embodiment, in order to form the images of the pinholes 81 to 89 on the surface of the wafer 2 to have substantially the same size, the slit 80
The pinholes 81 to 89 have different sizes as shown in FIG. FIG. 3 is a view of the slit 80 viewed from the optical axis direction of the lens system 9 in FIG. The hatched portion in the figure is a light shielding portion, which is formed by forming a light shielding film such as chrome on the surface of one prism forming the optical block 8. Here, if the diameter of each pin hole 81 to 89 and D ₈₁ to D _89, respectively, the diameter D ₈₁ to D ₈₉ so as to satisfy the following relationship is set.

D ₈₁ : D ₈₂ : D ₈₃ : D ₈₄ : D ₈₅ : D ₈₆ : D
₈₇ : _D88 : _D89 = β9 ₍₈₉₎ : β9 ₍₈₈₎ : β9 ₍₈₇₎ : β
_{9 (86)} : β _{9 (85)} : β _{9 (84)} : β _{9 (83)} : β _{9 (82)} : β
_{9 (81)} By setting as above, the measurement point 8 on the wafer 2
A pinhole image having substantially the same size is formed on each of 1 to 89. The lens system 9 irradiates the light beams from the pinholes 81 to 89 onto the wafer 2 at an incident angle φ, and forms respective pinhole images at measurement points 111 to 119 on the wafer 2. The lens system 9 includes an aperture stop 11 for making the NA of each light beam (corresponding to the pinholes 81 to 89) substantially uniform.

FIG. 4 is a view of the apparatus of this embodiment as viewed from above. The measurement points 111 to 119 are formed at positions separated from each other on the wafer 2 by causing each light beam to enter from the direction rotated by θ = 22.5 ° in the XY plane. The reason that each light beam is incident on the XY plane from the direction rotated by θ = 22.5 ° is for the purpose of facilitating the spatial arrangement of optical elements corresponding to each light beam. Regarding this, Japanese Patent Application No. 3-157822 previously proposed by the present applicant has been proposed.
Therefore, detailed description is omitted here.

In FIG. 2, the projecting means B comprises a measuring point 11
1 to 119, common mirror 12 and light receiving lens system 1
3, a stop aperture 14, and an optical system block 15.
Further, the imaging lens 1 is positioned with respect to the measurement points 111 and 112.
6, mirror 21, cylindrical lens 26 in common,
The imaging lens 17, the mirror 22, and the cylindrical lens 27 are commonly used for the measurement points 113 and 114,
5, the imaging lens 18 and the mirror 23 are moved to the measurement point 11
The image forming lens 19, the mirror 24, and the cylindrical lens 28 are commonly used for the measurement points 118 and 119 with respect to the measurement points 118 and 119.
Have an imaging lens 20, a mirror 25, and a cylindrical lens 29 in common. Also, measuring point 111
, The correction optical system 36 for the measurement point 113, and the correction optical system 37 for the measurement point 116.
Are provided with the correction optical system 38 for the measurement point 118, respectively.

A stopper aperture 14 provided in common to each of the measurement points 111 to 119 is provided with a high-order stop beam 14 generated when each light beam is reflected on the wafer 2 by a fine circuit pattern existing on the wafer 2. It has the function of cutting the diffracted light. Further, correction optical systems 35, 36, 3 provided for each of the measurement points 111, 113, 116, 118, respectively.
Reference numerals 7 and 38 each include a flat light flat plate and a lens system. The parallel flat plate is provided for correcting the optical path length, and the lens system is provided for correcting the magnification. These correction optical systems 35, 36, 37,
The imaging magnification and the imaging position of the imaging lenses 16, 17, 19, and 20 are corrected by 38.

The optical system block 15 is formed by laminating a pair of prisms so that their slopes face each other. A reflection surface such as aluminum is partially formed on the lamination surface by vapor deposition. , 112, 115, 118, 119, and measuring points 113, 114, 11
6 and 117 are transmitted.

The photoelectric conversion means C has one-dimensional CCD sensors 30, 31, 32, 33, 34 as position detecting elements. The output of each sensor is connected to the focus control device 40.

The measuring points 111 to 119 are measured by the light irradiation means A.
When light is applied to the nine points, nine reflected lights are generated. The light receiving lens system 13 has these nine reflected lights, that is, the measurement point 1
The light from the pinhole images formed on 11 to 119 is received and directed to the optical system block 15. At this time, the light receiving lens system 13 re-images the pinhole images on the measurement points 111 to 119 at positions 211 to 219 near the bonding surface of the optical system block 15.

The light reflected at the measurement points 111 and 112 is reflected on the bonding surface of the optical system block 15, and re-images pinhole images at positions 211 and 212, respectively, and then enters the imaging lens 16. . The light reflected at the measurement point 111 exits the imaging lens 16 and is reflected by the mirror 21, passes through the correction optical system 35 and the cylindrical lens 26, and enters the one-dimensional CCD sensor 30. At this time, the pinhole image on the measurement point 111 is
On the upper side, an image is formed again only in the direction corresponding to the array forming direction of the one-dimensional CCD sensor 30, and the direction orthogonal thereto is not in an image forming relationship due to the operation of the cylindrical lens 26. The light reflected at the measurement point 112 is transmitted to the imaging lens 16.
Is reflected by the mirror 21 and further passes through the cylindrical lens 26 to enter the one-dimensional CCD sensor 30. At this time, the pinhole image on the measurement point 112 is one-dimensional C
An image is formed again on the CD sensor 30 only in a direction coinciding with the array forming direction of the one-dimensional CCD sensor 30, and the direction orthogonal thereto does not have an imaging relationship due to the operation of the cylindrical lens 26. The light reflected at the measurement points 113 and 114 passes through the bonding surface of the optical system block 15 and re-forms pinhole images at positions 213 and 214, respectively.
Light enters the imaging lens 17. This is the same as the light reflected at the measurement points 111 and 112 until the light reaches the one-dimensional CCD sensor 31 thereafter. Further, the light reflected at the measurement point 115 is reflected on the bonding surface of the optical system block 15, re-images a pinhole image at a position 215, passes through the imaging lens 18,
The light is reflected by the mirror 23, and further reflected by the cylindrical lens 39.
And enters the one-dimensional CCD sensor 32. At this time, the pinhole image on the measurement point 115 is re-imaged on the one-dimensional CCD sensor 32 only in the direction corresponding to the array forming direction of the one-dimensional CCD sensor 32, and the direction orthogonal to this is formed by the action of the cylindrical lens 26. There is no imaging relationship. That is, the images of the two pinholes are simultaneously formed on the image 30 in a shifted relationship, thereby achieving the compactness of the apparatus. Until the light reflected at the measurement points 116 and 117 reaches the one-dimensional CCD sensor 33, it is the same as the light reflected at the measurement points 113 and 114,
The light reflected at the measurement points 118 and 119 is the same as the light reflected at the measurement points 111 and 112 until the light reaches the one-dimensional CCD sensor 34.

Thus, the nine measurement points 1 on the wafer 2
11 to 119 and a direction corresponding to the array forming direction of the light receiving surfaces of the one-dimensional CCDs 30 to 34 are conjugate to each other via the projection means B, so that the surface of the wafer 2 is inclined with respect to the optical axis Ax. However, the one-dimensional CCD sensors 30 to 34
The position of the light receiving surface in the direction corresponding to the array forming direction does not change. In response to a change in the surface position of the surface of the wafer 2 with respect to the direction of the optical axis Ax, that is, the height of the measurement points 111 to 119, , Pinhole 81
The positions of the images 89 to 89 will change. In the direction perpendicular to the array forming direction of the light receiving surfaces of the one-dimensional CCD sensors 30 to 34, the measurement points 111 to 119 on the wafer 2 are not conjugate to each other, so that the surface of the wafer 2 is aligned with the optical axis Ax. When tilted, the one-dimensional CCD sensors 30 to 34
The position of the light receiving surface in the direction orthogonal to the array forming direction changes. However, while the width of the light receiving surface of the one-dimensional CCD sensors 30 to 34 is at most several tens of μm, by appropriately setting the focal lengths of the cylindrical lenses 26 to 29 and 39, the measurement points 111 to It is possible to make the width of the light reflected at 119 sufficiently large, and even if the surface of the wafer 2 is inclined with respect to the optical axis Ax and the light incident position moves, the width of the light always collected One-dimensional CCD inside
It is easy to position the light receiving surfaces of the sensors 30 to 34, and there is no problem in measurement.

In this embodiment, the imaging lens 16 is located at the position 212.
The pinhole image (image of the measurement point 112) formed on the light-receiving surface of the one-dimensional CCD sensor 30 is re-imaged (one-dimensional CCD image).
(In the direction corresponding to the array forming direction of the sensor 30)
Magnification, the imaging lens 16 and the correction optical system 35
The pinhole image (the image of the measurement point 111) formed at the position 211 by the composite optical system formed by the image forming apparatus is re-imaged on the light receiving surface of the one-dimensional CCD sensor 30 (the one-dimensional CCD sensor 30).
(In the direction corresponding to the array forming direction of the light-receiving lens system 1).
Regarding 3, the surface of the wafer 2 and the plane inclined with respect to the optical axis of the light receiving lens system 13 including the positions 211 and 212 satisfy the Scheimpflug's condition, so that the pinholes 81 and Each of the images 82 (the images of the measurement points 111 and 112) is formed on the light receiving surface of the one-dimensional CCD sensor 30 at the same magnification (in the direction corresponding to the array forming direction of the one-dimensional CCD sensor 30). As a result, each image of the pinholes 81 and 82 formed on the light receiving surface of the one-dimensional CCD sensor 30 (measurement point 11
1, 112) are equal to each other.

Here, the measurement point 1 by the light receiving lens system 13
The imaging magnification of the pinhole image on the measurement point 112 by the light receiving lens system 13 is β _{13 (111)} , the imaging magnification of the pinhole image on the measurement point 112 is β _{13 (112)} , the imaging lens 16 and the correction optical system 35 _16-35 imaging magnification position 211 formed pinhole images of the synthetic optical system formed (with respect to the direction that matches the array forming direction of the one-dimensional CCD sensor 30) beta by _(211),
When the imaging magnification of the pinhole image formed at the position 212 by the imaging lens 16 (with respect to the direction corresponding to the array forming direction of the one-dimensional CCD sensor 30) is β _{16 (212)} ,
_{13 (111)} × β _{16-35 (211)} = β _{13 (112)} × β _{16 (212)} .

Similarly, each image of the measurement points 113 and 114,
And each image of the measurement points 116 and 117, and the measurement point 118,
For 119 each image _{of, β 13 (113) × β} 17-36 (213) = β 13 (114) × β 17 (214) β 13 (116) × β 19-37 (216) = β 13 ₍₁₁₇₎ × β _{19 (217)} β _{13 (118)} × β _{20-38 (218)} = β _{13 (119)} × β _{20 (219)} Furthermore, between all the measurement points including the measurement point 115 , Β _{13 (111)} × β _{16-35 (211)} = β _{13 (112)} × β _{16 (212)} = β _{13 (113)} × β _{17-36 (213)} = β _{13 (114)} × β _{17 ( 214)} = β _{13 (115)} × β _{18 (215)} = β _{13 (116)} × β _{19-37 (216)} = β _{13 (117)} × β _{19 (217)} = β _{13 (118)} × β _{20- The} projection optical system B is configured so as to satisfy _{38 (218)} = β _{13 (119)} × β _{20 (219)} . In the case where a plurality of measurement points are configured in the oblique incidence projection optical system as in the present embodiment, it is necessary to use the above-described correction optical system in order to configure the resolution and accuracy for detecting the height of each measurement point to be substantially equal. Become. This is disclosed in Japanese Unexamined Patent Publication No.
Since it is described in detail in Japanese Unexamined Patent Publication No. 1-2005, further description is omitted here.

FIG. 5 and FIG. 6 are diagrams showing light from two pinhole images entering the light receiving surface of the one-dimensional CCD sensor. 5 is a view from the same direction as FIG. 2, and FIG.
FIG. In FIGS. 5 and 6, the position 301 corresponds to the positions 211, 213, 216, and 218.
Position 302 corresponds to positions 212, 214, 217 and 219,
The imaging lens system 401 includes imaging lens systems 16, 17, 19,
20, the correction optical system 402 includes the correction optical systems 35, 36, 3
7, 38, the cylindrical lens 403 is the cylindrical lens 26, 27, 28, 29, the one-dimensional CCD sensor 501 is the one-dimensional CCD sensor 30, 31, 33, 3
4 respectively. The mirrors 21 and 2
Those corresponding to 2, 24 and 25 are not essential and are omitted here.

In FIG. 5, light emitted from a pinhole image at a position 301 passes through an imaging lens system 401 at a position decentered from the center, and passes through a correction optical system 402 and a cylindrical lens 403 (in this direction, a lens as a lens). After passing through (having no function), the light enters a position 601 on the light receiving surface of the one-dimensional CCD sensor 501. At this time, position 301 and position 6
Reference numeral 01 denotes a conjugate position with respect to a combined optical system composed of the imaging lens system 401 and the correction optical system 402 and has an image forming relationship. If the correction optical system 402 is not provided, an image is formed in front of the one-dimensional CCD sensor 501. I do. The light emitted from the pinhole image on the position 302 is focused on the imaging lens system 4 at a position decentered from the center.
After passing through the cylindrical lens 403 (having no function as a lens in this direction), the light enters the position 602 on the light receiving surface of the one-dimensional CCD sensor 501. At this time, the position 302 and the position 602 are
It is in a conjugate position with respect to 01 and has an imaging relationship.

In FIG. 6, light emitted from a pinhole image at a position 301 passes through an imaging lens system 401 at a position decentered from the center, further passes through a correction optical system 402, and a cylindrical lens at a position decentered from the center. After passing through 403 (which acts as a lens in this direction), the one-dimensional C
Light enters a position 601 on the light receiving surface of the CD sensor 501.
At this time, the position 601 is almost at the pupil position with respect to the position 301 via the combining optical system including the imaging lens system 401, the correction optical system 402, and the cylindrical lens 403. Light emitted from the pinhole image at the position 302 passes through the imaging lens system 401 at a position decentered from the center, and passes through a cylindrical lens 403 (having a function as a lens in this direction) at a position decentered from the center. After that, the light enters a position 602 on the light receiving surface of the one-dimensional CCD sensor 501. At this time,
The position 602 is the imaging lens system 401 and the cylindrical 4
It is almost at the position of the pupil with respect to the position 301 via the combining optical system consisting of 03. Position 301 and position 302 of two different points
Although the position of the pupil on the one-dimensional CCD sensor 501 differs strictly depending on the presence or absence of the correction optical system 402, the optical system is configured to be negligible for the purpose of condensing light at almost the same position. I have.

FIG. 7 and FIG. 8 are views showing that light from the pinhole image from the position 215 enters the light receiving surface of the one-dimensional CCD sensor. 7 shows a view from the same direction as FIG. 2, FIG. 8 shows a view from a direction orthogonal to FIG.
The mirror 23 is omitted because it is not essential.

In FIG. 7, light from the pinhole image at the position 215 passes through the imaging lens system 18 and is a cylindrical lens 39 (there is no function as a lens in this direction).
After passing through, the light enters a position 603 on the light receiving surface of the one-dimensional CCD sensor 32. At this time, the position 215 and the position 603 are at positions conjugate to the imaging lens system 18 and have an imaging relationship. In FIG. 8, light from the pinhole image at the position 215 passes through the imaging lens system 18 and has a cylindrical lens 39 (in this direction, acts as a lens).
After passing through, the light enters a position 603 on the light receiving surface of the one-dimensional CCD sensor 32. At this time, the position 603 is almost at the pupil position with respect to the position 215 via the combining optical system including the imaging lens system 18 and the cylindrical lens 39. Position 2
For the light from the pinhole image on 15, there is no particular need for the cylindrical lens 39, but the purpose of providing the cylindrical lens 39 here is to use the positions 215 and 30.
This is to make the resolution and accuracy of the height detection of 1, 302 almost equal.

One-dimensional CCD sensor 3 of photoelectric conversion means C
0, 31, 32, 33, and 34 are pinholes 81 and 82, 83, 84, and 8 formed on the light receiving surface, respectively.
5, 86 and 87, 88 and 89 (measurement points 111 and 1
12, 113 and 114, 115, 116 and 117, 11
8 and 119 are output, and the signals are input to the focus control unit 40. One-dimensional CC
Since the sizes of the images formed on the light receiving surfaces of the D sensors 30, 31, 32, 33, and 34 are substantially equal to each other, the measurement points 111, 112, 113, 114, 115, 116,
The resolutions and the accuracy of the height detection of 117, 118 and 119 can be made almost equal. The focus control means 40 includes one-dimensional CCD sensors 30, 31, 32, 3
3, 34 based on the output signals from
The height information 19 is obtained, and the position of the surface of the wafer 2 in the z direction (optical axis Ax direction) and the inclination with respect to the XY plane are detected. Then, a signal corresponding to the amount of driving of the wafer stage 3 necessary for positioning the surface of the wafer 2 on a plane (imaging plane) conjugate with the plane on which the circuit pattern of the reticle exists with respect to the projection lens system 1 is output to the stage controller 4. To enter. The stage control device 4 drives the wafer stage 3 according to the input signal, and thereby adjusts the position and attitude of the wafer 2.

In this embodiment, each of the measurement points 111 to 119
When calculating the surface position of the wafer 2 from the height information, an appropriate measurement point is selected according to conditions as described below. The conditions referred to here include, for example, the size and shape of the exposure area of the exposure light, the wafer shape in wafer peripheral exposure, and the like.

FIG. 9 shows the relationship between the arrangement of the measurement points 111 to 119 and the areas 901, 902, and 903 on which the circuit patterns are projected when all the measurement points are present on the wafer. If the projection area is larger than the area 901 with respect to the arrangement of the measurement points 111 to 119, the surface position of the area 901 is calculated using all nine measurement points 111 to 119 in the area. Alternatively, the surface position of the area 901 may be calculated using one measurement point 111, 113, 115, 117, 119 per one-dimensional CCD sensor. In the latter case, there is an advantage that the measurement point detection time and the calculation time are shortened by the small number of measurement points used, and the throughput is increased. On the other hand, if the projection area is smaller than the arrangement of the measurement points 111 to 119 as in the area 902, some of the measurement points 112, 114, 115,
The surface position of the region 902 is calculated by using 116 and 118. When the area is smaller as in the area 903,
The surface position of the region 903 is calculated using the measurement points 112, 114, 115, 116, and 118. Alternatively, the surface position of the region 903 may be calculated using only the measurement point 115, although the inclination cannot be corrected.

FIG. 10 shows each measurement point 1 when some of the measurement points are present on the wafer 2 indicated by oblique lines in the periphery of the wafer 2.
Area 9 where the arrangement of 11 to 119 and the circuit pattern are projected
04 and 905 are shown. For the region 904, the measurement point 117 is not on the wafer 2, and the measurement point 119 is located at the peripheral boundary of the wafer 2. In this case, the measuring point 118 instead of the measuring point 119 and the measuring points 111, 1
The surface position of the region 904 is calculated using a total of 13 and 115 points. In this case, the surface position of the region 904 may be calculated using all the six measurement points included on the wafer 2. The measurement point 1 is set for the area 905.
16 is not on wafer 2. Therefore, in this case, measurement point 11
The area 90 is calculated using a total of four points of 2, 114, 115 and 118.
5 is calculated.

FIG. 11 shows each measurement point 1 when some of the measurement points are present on the wafer 2 indicated by oblique lines in the periphery of the wafer 2.
Area 9 where the arrangement of 11 to 119 and the circuit pattern are projected
06 and 907. The surface position of the area 906 is calculated using a total of three measurement points 111, 113, and 115 for the area 906. Similarly to the above, in this case, the surface position of the area 906 may be calculated using all the five measurement points on the wafer 2. The surface position of the region 907 is calculated using a total of three measurement points 112, 114, and 115 for the region 907.

Incidentally, if an arithmetic processing circuit is provided for each one-dimensional CCD sensor and arithmetic processing is performed in parallel, the throughput can be further improved. Further, if an arithmetic processing circuit is provided for each measurement point and calculation processing is performed in parallel, it is possible to further increase the speed. Further, if all points (9 points) are used, more precise position setting can be performed.

Next, some modifications of the above embodiment will be described below. In recent years, the exposure area of the projection lens 1 that performs projection exposure of a circuit pattern tends to be large. This is due to the requirement to improve the yield by forming a plurality of chips at once in the exposure area. For example, considering a memory chip often formed by a projection exposure apparatus, the memory chip generally has a rectangular shape in many cases, and a rectangular exposure area is required even when a plurality of memory chips are collectively exposed.

FIG. 12 shows an exposure area 9 of a single memory chip.
FIG. 13 is a diagram showing an example in which three memory chips 08 are arranged vertically. FIG. 13 shows the measurement points shown in FIG. 4 so as to be suitable for the batch exposure exposure area 909 when three memory chips are arranged vertically. It is a figure showing the example which changed arrangement. In the example of FIG. 13, the measurement points 111, 113, 117,
119 and the central measurement point 115 are the same as in FIG.
Measuring points 122, 124, 126, 128 respectively corresponding to measuring points 112, 114, 116, 118 in FIG.
To the inside of the measurement points 111, 113, 117, 119
It is provided at a position where the direction is longer than the X direction. When performing projection exposure of the circuit pattern on the rectangular exposure area 909, the measurement points 122, 124, 12
Exposure area 9 using 6, 128 and central measurement point 115
09 is to be determined.

FIG. 14 shows an example in which the arrangement of the measurement points shown in FIG. 4 is changed and arranged in the diagonal direction, the xy direction, and the center in the area 901. As shown in FIG. 13, the measurement points 111, 113, 117, and 119 at the four corners of the square exposure screen and the measurement point 115 at the center are the same as in FIG. 4, but the measurement points 112, 114, 116, and 118 in FIG. As shown in the figure, measurement points 132, 134, 136, and 138 are arranged in regions inside the measurement points 111, 113, 117, and 119 so that diagonals are oriented in the x and y directions. As a result, the distance between the measurement points can be made substantially uniform in the area 901.
The surface shape of the region 901 can be determined with higher accuracy.

FIG. 15 shows the cylindrical lens 40 of FIG.
One-dimensional C using parallel plates 404 and 405 instead of
FIG. 3 shows a diagram in which light from two pinhole images is incident on a light receiving surface of a CD sensor, as viewed from a direction orthogonal to FIG. 2. Note that, when viewed from the same direction as FIG. 5, the parallel plates 404 and 405 in this direction are omitted because they have no function of bending light. In FIG. 15, the light emitted from the pinhole image on the position 301 is focused on the imaging lens system 4 at a position decentered from the center.
After passing through the correction optical system 402 and the parallel plate 404, the light enters the position 601 on the light receiving surface of the one-dimensional CCD sensor 501. At this time, the position 301 and the position 601 are conjugate with respect to the combined optical system including the imaging lens system 401 and the correction optical system 402, and have an image forming relationship. That is, when there is no correction optical system 402, one-dimensional CC
An image is formed before the D sensor 501. The light emitted from the pinhole image at the position 302 passes through the imaging lens system 401 at a position decentered from the center, changes its direction through the parallel plate 405, and then changes its position on the light receiving surface of the one-dimensional CCD sensor 501. Light enters 602. At this time, the position 302 and the position 602 are conjugate with respect to the imaging lens system 401 and have an imaging relationship. Even with such a configuration, it is possible to measure the luminous flux emitted from two different points with a common one-dimensional CCD sensor.

FIG. 16 shows the cylindrical lens 40 of FIG.
3 shows a view in which light from two pinhole images is incident on a light receiving surface of a one-dimensional CCD sensor using a wedge-shaped prism 407 instead of 3, and is viewed from a direction orthogonal to FIG. Note that the drawing viewed from the same direction as FIG. 5 does not show the wedge prism 407 in this direction because it has no function of bending light. In FIG. 16, light emitted from a pinhole image at a position 301 passes through an imaging lens system 401 at a position decentered from the center, passes through a correction optical system 402, and passes through a wedge prism 407 at a position decentered from the center. After being changed, the position 601 on the light receiving surface of the one-dimensional CCD sensor 501 is changed.
Light enters. At this time, the position 301 and the position 601 are in a conjugate position with respect to the combined optical system including the imaging lens system 401 and the correction optical system 402, and have an image forming relationship.
If there is no 02, an image is formed before the one-dimensional CCD sensor 501. The light emitted from the pinhole image at the position 302 passes through the imaging lens system 401 at a position decentered from the center, passes through the wedge prism 407 at a position decentered from the center, and changes its direction. The light enters a position 602 on the light receiving surface 501. At this time, position 302 and position 6
Numeral 02 is at a conjugate position with respect to the imaging lens system 401 and has an imaging relationship. Even with such a configuration, light beams emitted from two different points can be measured by a common one-dimensional CCD sensor.

FIG. 17 shows the cylindrical lens 40 shown in FIG.
Using mirrors 408 and 409 instead of 3
FIG. 3 is a diagram illustrating a view in which light from two pinhole images is incident on a light receiving surface of a CD sensor, as viewed from a direction orthogonal to FIG. 2. It should be noted that the drawing viewed from the same direction as FIG. 5 will not be described because the mirrors 408 and 409 have no function of bending light in this direction. In FIG. 17, light emitted from a pinhole image at a position 301 is formed at a position decentered from the center by an imaging lens system 401.
After being reflected by the correction optical system 402 and the mirror 408 to change the direction, the light enters the position 601 on the light receiving surface of the one-dimensional CCD sensor 501. At this time, position 301 and position 6
Numeral 01 is in a conjugate position with respect to the combined optical system composed of the imaging lens system 401 and the correction optical system 402 and forms an imaging relationship. If the correction optical system 402 is not provided, an image is formed in front of the one-dimensional CCD sensor 501. .

The light emitted from the pinhole image at the position 302 passes through the imaging lens system 401 at a position eccentric from the center, is reflected by the mirror 409 and is changed in direction, and then received by the one-dimensional CCD sensor 501. Light enters a position 602 on the surface. At this time, the position 302 and the position 602 are
It is in a conjugate position with respect to 01 and has an imaging relationship. Even with such a configuration, light beams emitted from two different points can be measured by a common one-dimensional CCD sensor.

When the configuration shown in FIGS. 15, 16 and 17 is adopted, the position 215 is assumed to have the configuration shown in FIG. FIG. 18 has a configuration in which the cylindrical lens 39 of FIG. 8 is omitted, and the same reference numerals denote the same members. 18, the light from the pinhole image at the position 215 passes through the imaging lens system 18 and then enters the position 603 on the light receiving surface of the one-dimensional CCD sensor 32. At this time,
The position 215 and the position 609 are conjugate to the imaging lens system 18 and have an imaging relationship. For the light from the pinhole image on the position 215, the cylindrical lens 39 is not originally required, and here the cylindrical lens 39 is used.
The purpose of eliminating is to make the resolution and accuracy of height detection at the position 215 and the positions 301 and 302 substantially equal.

FIG. 19 is a view showing a modification in which the apparatus shown in FIG. 1 is partially modified. In this figure, only the different parts are shown, and the optical system block 8 and thereafter are the same as in FIG.
The light source 51 is a lamp that emits light of white or a plurality of different wavelengths.
By 1, light enters the incident end face of the fiber system 71. The light that has passed through the fiber system 71 exits from the emission end face of the fiber system 71 and irradiates the slit 81. Similarly, the fiber systems 72 to
A slit 79 is provided for each of the slits 82 to 89 and has an individual light source to illuminate the slits 82 to 89. Here, for simplicity, the light source unit 50 is shown only for the fiber system 71. By providing a light source for each measurement point in this way, even when the reflectance under the measurement point is different, the amount of light is individually adjusted and stable detection is always possible.

FIG. 20 shows a case where the light source unit 50 in FIG.
9 shows a further modified example constituted by using Nos. 2 and 53.
The light emitted from the monochromatic light source 52 passes through the condenser lens 62, passes through the beam splitter 64, and then enters the incident end face of the fiber system 71. The light emitted from the monochromatic light source 53 is
After passing through 3 and being reflected by the beam splitter 64, the light enters the incident end face of the fiber system 71. The beam splitter 64 has transmissivity for light of a specific wavelength, and has reflection characteristics for light of another wavelength. Thus, a multi-wavelength light source can be configured from the two monochromatic light sources 52 and 53 having different wavelengths. A monochromatic light source such as an LED or a laser is a light source that has a quick response characteristic and is easy to use for the purpose of adjusting the amount of light, but has a disadvantage that it is susceptible to thin-film interference because it is monochromatic. With this configuration, the light source becomes a multi-wavelength light source, and the effect of thin-film interference can be reduced.

[0044]

According to the present invention, an appropriate measurement point is selected from a plurality of measurement points and measured according to the measurement conditions such as the size of the exposure area where the pattern transfer is performed. It is possible to provide an excellent surface position detecting device and an exposing device which are highly accurate and versatile.

[Brief description of the drawings]

FIG. 1 is a side view of an apparatus according to an embodiment of the present invention.

FIG. 2 is a side view of an apparatus according to an embodiment of the present invention.

FIG. 3 is a view showing a shape of a slit of the optical block shown in FIG. 1;

FIG. 4 is a view of the apparatus of the present embodiment as viewed from above.

FIG. 5 is a diagram in which light from two pinhole images enters a light receiving surface of a one-dimensional CCD sensor.

FIG. 6 is a diagram in which light from two pinhole images enters a light receiving surface of a one-dimensional CCD sensor.

FIG. 7 is a diagram in which light from a pinhole image from a position 215 enters a light receiving surface of a one-dimensional CCD sensor.

FIG. 8 is a diagram in which light from a pinhole image from a position 215 enters a light receiving surface of a one-dimensional CCD sensor.

FIG. 9 is a diagram showing a relationship between the arrangement of each measurement point and a projection area of a circuit pattern.

FIG. 10 is a diagram showing the relationship between the arrangement of each measurement point at the peripheral portion of the wafer and the projection area of the circuit pattern.

FIG. 11 is a diagram showing the relationship between the arrangement of each measurement point at the peripheral portion of the wafer and the projection area of the circuit pattern.

FIG. 12 is a diagram showing an exposure area of a memory chip.

FIG. 13 is a diagram showing a modified example of the arrangement of a plurality of measurement points.

FIG. 14 is a diagram showing a modified example of the arrangement of a plurality of measurement points.

FIG. 15 is a diagram showing a modification of the configuration shown in FIG. 6;

FIG. 16 is a diagram showing a modification of the configuration shown in FIG. 6;

FIG. 17 is a diagram showing a modification of the configuration shown in FIG. 6;

FIG. 18 is a diagram showing a modification of the configuration shown in FIG.

FIG. 19 is a diagram showing a modification of the surface position detecting device shown in FIG.

FIG. 20 is a diagram showing a modification of the surface position detecting device shown in FIG. 1;

[Explanation of symbols]

 9, 13 Lens system 16-20 Imaging lens system 35-38 Correction optical system 81-89 Pinhole 111-119 Measurement point 30-34 One-dimensional CCD sensor

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01B 11/00-11/30 G03F 7/207 H01L 21/027

Claims (2)

(57) [Claims] 1. A means for irradiating a plurality of different measurement positions on a surface to be measured with a light beam in an oblique direction, receiving light reflected at the measurement positions, and based on a detection signal at each measurement position. Means for obtaining position information for each measurement position of the surface to be inspected, comprising: a plurality of one-dimensional array sensors for receiving the reflected light; and reflected light from a plurality of different measurement points. same front part of the multiple reflected light of the
A surface position detection device, wherein the surface position is detected simultaneously by the one-dimensional array sensor . 2. An exposure optical system for projecting and exposing a mask pattern on a wafer mounted on a stage, and a light beam obliquely directed to a plurality of different measurement positions on a test surface of the wafer. Means for irradiating, means for receiving light reflected at the measurement position, means for obtaining position information for each measurement position of the surface to be measured based on a detection signal at each measurement position, and the obtained surface to be measured Means for performing control so that the surface to be inspected matches the image forming surface of the exposure optical system according to the positional information of the plurality of one-dimensional array sensors for receiving the reflected light. the a, before the same part of the plurality reflected light of the reflected light from the phase different measuring points
An exposure apparatus, wherein the one-dimensional array sensor simultaneously detects the light.