JP2003068613A - Alignment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixed alignment apparatus that, for example, when it is applied to a proximity exposure device, aligns an original plate with a substrate, without obstructing the optical path of exposure. SOLUTION: This device comprises irradiation systems (4-6) for, along a substantially inclined optical path, irradiating a first diffraction grating mark (7) formed on a first substrate (1) and a second diffraction grating mark formed on a second substrate (3) with a coherent light, imaging systems (6, 9-11) for forming the images, based on the diffraction lights from the first and second diffraction grating marks, respectively, and a detection system (12) for detecting the images of the first and second diffraction grating marks formed via the imaging systems. The first substrate is aligned with the second substrate based on the output of the detection system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning device, and more particularly, to a proximity exposure device for transferring and printing a pattern of a semiconductor integrated circuit or a DNA chip, which is arranged in close proximity to an original plate on which a minute pattern is drawn and below the original plate. The present invention relates to a device for aligning a substrate.

[0002]

2. Description of the Related Art In the manufacture of semiconductor integrated circuits and DNA chips, a proximity exposure apparatus is used which transfers and prints a fine pattern drawn on an original plate onto a substrate arranged under the original pattern. In this case, not only one original plate is used, but a plurality of original plates are usually used. The patterns of a plurality of original plates are sequentially transferred onto the same substrate, but it is necessary that the plurality of original patterns are accurately superimposed on each other on the substrate. Conventionally, in a proximity exposure apparatus, an alignment device is used to align the original plate and the substrate.

The position detecting device used in the semiconductor manufacturing apparatus described in Japanese Patent Application Laid-Open No. 10-242037 is superposed with a small distance in the process of transferring the circuit pattern on the mask surface onto the wafer using exposure light. The mask and the wafer are aligned. This position detecting device detects by observing an alignment mark formed on the mask and the wafer.

This position detecting device comprises an illuminating optical device and a detecting optical device. Each device has an optical axis oblique to the mask surface outside the exposure area so as not to block the exposure light during exposure. It was arranged so that.
In addition, the detection optical device detects scattered light from the alignment mark (mask mark and wafer mark),
The positional relationship between the wafer and the mask is detected.

[0005]

In the conventional position detecting device, since the optical axis of the detecting optical system of the detecting optical device is arranged obliquely with respect to the normal to the mask surface, the entire area of the alignment mark is covered. However, there is a problem that only a part of the alignment mark can be focused, and the correct positional relationship between the mask mark and the wafer mark cannot be accurately obtained.

Further, since the detection optical device performs detection using scattered light, there is a problem that it is easily affected by noise. Further, the conventional position detecting device cannot detect the gap between the mask and the wafer.

The present invention has been made in view of the above problems, and when applied to a proximity exposure apparatus, for example,
An object of the present invention is to provide a positioning device that can perform the positioning of the original plate and the substrate with high accuracy without blocking the exposure optical path.

[0008]

In order to solve the above-mentioned problems, according to the present invention, the first members are arranged in parallel and close to each other.
An alignment apparatus for a proximity exposure apparatus, which aligns a substrate and a second substrate, including an illumination optical system,
The first diffraction grating mark formed on the substrate and the second diffraction grating mark formed on the second substrate include an illumination system for illuminating the coherent light, and an imaging optical system, and the first diffraction grating mark is formed by a diffractive action. An imaging system for detecting a diffraction image from the first diffraction grating mark and a diffraction image from the second diffraction grating mark is provided, and the illumination system and the imaging system are arranged outside the exposure area and on the same side. In addition, the optical axis of the imaging optical system and the first
There is provided an alignment device characterized by being arranged in parallel with a normal line of a substrate.

According to a preferred embodiment of the present invention, the illumination light exit side objective lens of the illumination optical system and the diffracted light incidence side objective lens of the imaging optical system are common optical systems. The optical axis of the common optical system and the normal line of the first substrate are arranged in parallel. Further, it is preferable that the common optical system includes a semi-circular lens obtained by cutting a part of a circular lens, or a cylindrical lens obtained by cutting a part of a cylindrical lens in a refracting direction.

According to a preferred aspect of the present invention, the first diffraction grating mark and the second diffraction grating mark are:
Deflection for guiding the diffracted light from the first diffraction grating mark and the diffracted light from the second diffraction grating mark along substantially different directions, with a substantially different grating pitch. Have members. Further, the detection system has a first split light receiving element for detecting the diffraction image of the first diffraction grating mark and a second split light receiving element for detecting the diffraction image of the second diffraction grating mark. Then, based on the output of the first divided light receiving element and the output of the second divided light receiving element, the positional deviation between the first substrate and the second substrate along the in-plane direction of the first substrate is measured. Preferably.

Furthermore, according to a preferred embodiment of the present invention,
The imaging system has a dividing member that divides the diffracted light from the first diffraction grating mark and the diffracted light from the second diffraction grating mark symmetrically with respect to the longitudinal direction of the mark, and is divided by the dividing member. Based on the positional relationship between the one mark image formed by the one diffracted light from the first diffraction grating mark and the other mark image formed by the other diffracted light, the normal direction of the first substrate is determined. The positional deviation of the first substrate along the distance is measured, and one mark image formed by one diffracted light from the second diffraction grating mark divided by the dividing member and the other formed by the other diffracted light. The positional deviation of the second substrate along the normal direction is measured based on the positional relationship with the mark image.

According to a preferred aspect of the present invention, the image forming system includes a beam splitter for splitting the diffracted light from the first diffraction grating mark and the diffracted light from the second diffraction grating mark, respectively. Based on one diffracted light from the first diffraction grating mark and one diffracted light from the second diffraction grating mark, which is split by the beam splitter, along the in-plane direction of the first substrate. Measuring the positional deviation between the first substrate and the second substrate,
Based on the other diffracted light from the first diffraction grating mark and the other diffracted light from the second diffraction grating mark split by the beam splitter, the first diffracted light along the normal direction of the first substrate. The positional deviation between the substrate and the second substrate is measured.

Furthermore, according to a preferred embodiment of the present invention,
The first substrate is an original plate on which a pattern to be exposed is drawn, and the second substrate is a photosensitive substrate to which the pattern of the original plate is exposed and transferred in a predetermined state in which the pattern is exposed. Is.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram schematically showing a configuration of an alignment device according to an embodiment of the present invention. Also,
FIG. 2 is a diagram schematically showing the configuration of the lateral alignment section of the alignment apparatus according to this embodiment. on the other hand,
FIG. 7 is a diagram schematically showing the configuration of the vertical alignment unit of the alignment device according to the present embodiment. In the present embodiment, alignment between the original plate and the substrate in the proximity exposure apparatus, that is, horizontal alignment (alignment along the in-plane direction of the original plate) and vertical alignment (in the normal direction of the original plate) The present invention is applied to (alignment along). In other words, the alignment device according to the present embodiment includes the lateral alignment portion MSh for performing lateral alignment and the vertical alignment portion MSv for performing vertical alignment. .

Referring to FIG. 2, the lateral alignment section provides a light source 4 for supplying light having a long coherence length (coherent light).
Is equipped with. As the light source 4, for example, a semiconductor laser or a He-Ne laser can be used. The light beam Lb emitted from the light source 4 is converted into a substantially parallel light beam through the lens 5 (objective lens) and the lens 6 (objective lens), and then the alignment marks formed on the original plate 1 and the substrate 3 are applied to the original plate 1. Illuminate from an angle with respect to the normal direction.
Here, the lens 6 is formed as a partial lens (semi-circular lens) obtained by cutting out only the portion indicated by the solid line from the circular lens so as not to block the exposure optical path. As the lens 6, for example, a partial lens (such as a cylindrical lens) cut out from a cylindrical lens can be used.

FIG. 3 is a view schematically showing the arrangement of the alignment marks formed on the original plate and the substrate. As shown in FIG. 3, on the original plate 1, a pair of one-dimensional diffraction grating marks 7a are arranged in the horizontal direction in the drawing in the vicinity of the exposure region of the pattern 2.
And 7b are formed, and one one-dimensional diffraction grating mark 7c is formed in the vertical direction in the drawing in the vicinity of the exposure area of the pattern 2. Similarly, on the substrate 3, a pair of one-dimensional diffraction grating marks 8a and 8b are formed in the horizontal direction in the drawing so as to be aligned with the pair of one-dimensional diffraction grating marks 7a and 7b. One one-dimensional diffraction grating mark 8c is formed in the vertical direction in the figure so as to be aligned.

Therefore, the alignment apparatus according to the present embodiment has a first lateral alignment portion corresponding to the one-dimensional diffraction grating marks 7a and 8a and a second lateral direction alignment portion corresponding to the one-dimensional diffraction grating marks 7b and 8b. Alignment part,
It has a third lateral alignment portion corresponding to the one-dimensional diffraction grating marks 7c and 8c. Hereinafter, since the configurations of the respective lateral alignment portions are basically the same, the suffixes a to c are omitted, and the configuration of one lateral alignment portion corresponding to the one-dimensional diffraction grating marks 7 and 8 and The operation will be described.

In the lateral alignment portion shown in FIG. 2, the one-dimensional diffraction grating marks 7 and 8 formed on the original 1 and the substrate 3 are obliquely illuminated. Thus, diffracted light is generated from the illuminated one-dimensional diffraction grating marks 7 and 8. FIG. 4 is a diagram illustrating diffracted light generated from the one-dimensional diffraction grating mark formed on the original plate and the substrate. Figure 4
Referring to, when the one-dimensional diffraction grating mark 7 (or 8) formed on the original 1 (or the substrate 3) is obliquely irradiated with the parallel light flux Li, in addition to the regular reflection light Lr, the diffraction in the + direction is performed. Light DL + and diffracted light DL− in the − direction are generated.
In this embodiment, the − direction diffracted light DL − generated along the optical path close to the irradiation optical path of the parallel light flux Li is used. Thereby, the lens 6 common to the illumination system and the imaging system can be arranged close to the exposure area of the pattern 2.

Here, the pitch of the one-dimensional diffraction grating mark 7 (or 8) is P, the wavelength of the parallel light flux Li is λ,
If the incident angle of the parallel light flux Li is θi, the minus first-order diffracted light D
The angle θ− of L− satisfies the following expression (1). sin (θ −) = − λ / P + sin (θi) (1)

Referring to FIG. 2, -1 from the one-dimensional diffraction grating marks 7 and 8 formed on the original plate 1 and the substrate 3.
The next-order diffracted lights DLm and DLw enter the lens 6 along an oblique optical path that is substantially the same as the incident optical path. When the pitch of the one-dimensional diffraction grating mark 7 and the pitch of the one-dimensional diffraction grating mark 8 are different, the diffraction angle of the -1st-order diffracted light DLm and -1
This is different from the diffraction angle of the next-order diffracted light DLw. The diffracted lights DLm and DLw become convergent lights through the lens 6, are reflected in the horizontal direction by the plane mirror 9, and then enter the triangular prism 10. At this time, the diffracted light DLm and the diffracted light DLw are spatially separated due to the different diffraction angles.

Diffracted lights DLm and DLw which are incident on the triangular prism 10 substantially in parallel with each other are reflected by the triangular prism 1.
They are respectively biased away from each other by 0. The diffracted lights DLm and DLw deflected through the triangular prism 10 are guided onto the four-divided position detection element 12 through the lens 11. In the present embodiment, the intermediate position between the original plate 1 and the substrate 3 and the light receiving surface of the four-divided position detecting element 12, which is a pair of two two-divided position detecting elements, are set to be substantially optically conjugate. Further, the four-divided position detection element 12 is
Four photoelectric devices Dma and Dm having the same characteristics as each other
It is a position detection element composed of b, Dwa, and Dwb.

Therefore, a real image of the one-dimensional diffraction grating mark 7 and a real image of the one-dimensional diffraction grating mark 8 are formed on the four-divided position detecting element 12. More specifically, 1 is provided on the two-divided light receiving element including the photoelectric elements Dma and Dmb.
A real image of the three-dimensional diffraction grating mark 7 is formed, and the photoelectric element Dw
A real image of the one-dimensional diffraction grating mark 8 is formed on the two-divided light receiving element composed of a and Dwb. As described above, the triangular prism 10 allows the diffracted light DLm from the one-dimensional diffraction grating mark 7 and the diffracted light DL from the one-dimensional diffraction grating mark 8.
It constitutes a deflecting member for guiding w along substantially different directions. In other words, due to the deflecting action of the triangular prism 10, the position of the real image of the one-dimensional diffraction grating mark 7 and the position of the real image of the one-dimensional diffraction grating mark 8 on the four-divided position detection element 12 can be spatially largely separated. Therefore, they do not interfere with each other.

FIG. 5 is a diagram showing a positional relationship between a pair of one-dimensional diffraction grating marks formed on the original plate and the substrate and a positional relationship between a pair of real images formed on the four-divided position detecting element. That is, in FIG. 5, the positional relationship between the one-dimensional diffraction grating mark 7 and the one-dimensional diffraction grating mark 8 as viewed along the normal line direction of the original plate 1 and the normal direction of the light receiving surface of the four-divided position detection element 12 are shown. Real image 7 of the one-dimensional diffraction grating mark 7 seen along
The positional relationship between I and the real image 8I of the one-dimensional diffraction grating mark 8 is shown. The real images 7I and 8I are shown as a single linear shape instead of the diffraction grating shape because they are real images only by the -1st order diffracted light.

As shown in FIGS. 5A to 5C, when the one-dimensional diffraction grating marks 7 and 8 move in a direction orthogonal to the longitudinal direction, that is, in the lateral direction, their real images 7I and 8 are obtained.
I will also be displaced on the four-divided position detection element 12 in the direction orthogonal to the longitudinal direction, that is, in the lateral direction. In the four-divided position detection element 12, D from the output of the photoelectric element Dmb
Signal Sm from which the output of ma is subtracted, and photoelectric element Dw
A signal Sw is obtained by subtracting the output of Dwa from the output of b.

FIG. 6 shows a one-dimensional diffraction grating mark 7 or 8.
FIG. 6 is a diagram showing how the signal Sm or Sw changes when (in the original plate 1 or the substrate 3) is moved in the lateral direction. The signals Sm and Sw are adjusted so that they become 0 when the real images 7I and 8I are located at the boundary between the two photoelectric elements on the left and right. In other words, the original plate 1 and the substrate 3 are relatively moved by moving the one-dimensional diffraction grating marks 7 and 8 (and thus the original plate 1 and the substrate 3) laterally so that the signals Sm and Sw become 0 at the same time. It can be aligned along the lateral direction.

At this time, as long as the one-dimensional diffraction grating marks 7 and 8 are within the area illuminated by the irradiation light beam Lb, their positional deviation directions can be known based on the positive and negative signs of the signals Sm and Sw. Therefore, the alignment control is easy, and quick alignment is possible. In addition,
The above-described lateral alignment operation is performed in order to adjust the two orthogonal directions in the plane of the original plate 1 and the substrate 3 and the rotation direction, and the three pairs of one-dimensional diffraction grating marks 7a to 7c and 8a.
~ 8c. Further, in the above description, the four-division detector is used to detect the positions of the real images 7I and 8I, but the present invention is not limited to this, and for example, a two-dimensional image sensor (two-dimensional CCD or the like) or a position sensor described later is used. It can also be used.

FIG. 7 is a view schematically showing the arrangement of the vertical alignment section of the alignment apparatus according to this embodiment. The alignment device according to the present embodiment includes a first vertical alignment portion corresponding to the one-dimensional diffraction grating marks 7a and 8a, and one-dimensional diffraction grating marks 7b and 8b.
And a third vertical alignment portion corresponding to the one-dimensional diffraction grating marks 7c and 8c. Hereinafter, since the configuration of each vertical alignment unit is basically the same, the suffixes a to c are omitted, and the configuration of one vertical alignment unit corresponding to the one-dimensional diffraction grating marks 7 and 8 and The operation will be described. 7A is a sectional view taken along the longitudinal direction of the one-dimensional diffraction grating mark 7, and FIG. 7B is a sectional view taken along a direction orthogonal to the longitudinal direction of the one-dimensional diffraction grating mark 7. is there.

Referring to FIG. 7, the vertical alignment unit has an irradiation system (4 to 4) common to the horizontal alignment unit described above.
6) is provided. That is, even in the vertical alignment section, the light flux Lb emitted from the light source 4 is reflected by the lens 5
And after being converted into a substantially parallel light flux via the lens 6,
The one-dimensional diffraction grating marks 7 and 8 formed on the original 1 and the substrate 3 are illuminated. And the one formed on the original plate 1
-1st-order diffracted light DBm from the one-dimensional diffraction grating mark 7 and -1 from the one-dimensional diffraction grating mark 8 formed on the substrate 3
The next-order diffracted light DBw enters the aperture member 13 via the lens 6. The opening member 13 is formed with two openings 13a and 13b spaced from each other in FIG. 7 (b).

Therefore, of the -1st-order diffracted light DBm from the one-dimensional diffraction grating mark 7, the left portion DB in FIG. 7B.
ma and the right side portion DBmb are the openings 13a, respectively.
And 13b to enter the triangular prism 14. Further, in the −1st-order diffracted light DBw from the one-dimensional diffraction grating mark 8, the left side portion DBwa and the right side portion DBwb in FIG. 7B enter the triangular prism 14 through the openings 13a and 13b, respectively. Diffracted light DBma
And DBmb and DBwa and DBwb are deflected away from each other via the triangular prism 14 having the same function as the above-mentioned triangular prism 10.

The diffracted lights DBma and DBwa deflected through the triangular prism 14 reach the position sensors PSma and PSwa through the lens 15a. On the other hand, the diffracted light DB deflected through the triangular prism 14
mb and DBwb reach the position sensors PSmb and PSwb via the lens 15b. Each position sensor outputs an electric signal proportional to the position of the center of gravity of the total amount of incident light. FIG. 8 is a diagram of the four position sensors PSma, PSmb, PSwa, and PSwb viewed from directly above in the figure in FIG. 7B.

In this embodiment, the original plate 1 and the substrate 3 are used here.
Intermediate positions between and are position sensors PSma, PSmb, PSw
It is set to be substantially conjugate with the light receiving surfaces of a and PSwb. Therefore, the position sensors PSma and PSmb
Are formed with real images 7Ia and 7Ib of the one-dimensional diffraction grating mark 7 formed on the original plate 1, and the position sensors PSwa and PSwb are formed with real images 8Ia and 8Ib of the one-dimensional diffraction grating mark 8 formed on the substrate 3 (see FIG. 10). Are formed). In this way, the opening member 14 constitutes a dividing member that divides the diffracted light DBm from the one-dimensional diffraction grating mark 7 and the diffracted light DBw from the one-dimensional diffraction grating mark 8 symmetrically with respect to the longitudinal direction of the mark. . Further, the triangular prism 14 constitutes a deflecting member for guiding the diffracted light DBm from the one-dimensional diffraction grating mark 7 and the diffracted light DBw from the one-dimensional diffraction grating mark 8 along substantially different directions.

FIG. 9 is a diagram for explaining the principle of the vertical position detecting method according to the present invention. In addition, FIG.
FIG. 3 is a diagram showing a positional relationship of real images formed on the light receiving surfaces of a pair of position sensors in FIG. In FIG. 9, only the substrate 3 is shown as the surface to be detected, and the original 1 is omitted for the sake of simplicity of explanation and clarity of the drawing. Further, in FIG. 9, a desired position 3o of the substrate 3 is indicated by a solid line, a position 3u of the substrate 3 displaced in the upward direction is indicated by a broken line, and a position 3d of the substrate 3 displaced in the downward direction is indicated by a dashed line. There is. Therefore, in FIG. 10, the one-dimensional diffraction grating marks 8 formed on the light receiving surfaces of the pair of position sensors PSwa and PSwb.
7 shows the positional relationship between the real images 8Ia and 8Ib.

The substrate 3 is placed at a desired position 3o along the vertical direction.
10B, as shown in FIG. 10B, the position sensor P
The interval between the real image 8Ia formed on Swa and the real image 8Ib formed on the position sensor PSwb is Lo. On the other hand, when the substrate 3 moves up and down to the positions 3u and 3d, as shown in FIGS. 10A and 10C, the real image 8I is obtained.
The distance between a and 8Ib changes to Lu and Ld, respectively. In FIG. 10, the real images shown in (a) and (c) are thicker than the real images shown in (b) because blurring of the image occurs due to the collapse of the conjugate relationship with the position sensor. However, since the position sensors PSwa and PSwb output electric signals proportional to the position of the center of gravity of the real image, the center distance L between the real images 8Ia and 8Ib can be accurately detected even when the substrate 3 moves up and down to some extent. it can.

Therefore, the substrate 3 can be set at a desired position 3o by moving the substrate 3 in the vertical direction so that the distance between the real images 8Ia and 8Ib becomes equal to Lo. At this time, the distance between the real images 8Ia and 8Ib is L
If it is smaller than o, the substrate 3 may be moved upward, and if the interval is larger than Lo, the substrate 3 may be moved downward. Similarly, by moving the original plate 1 in the vertical direction so that the interval between the real images 7Ia and 7Ib becomes equal to a value Lo ′ that is slightly longer than Lo, the original plate 1 can be set at a desired position 1o. At this time, the real image 7I
If the distance between a and 7b is smaller than Lo ', the original plate 1 may be moved upward, and if the distance is larger than Lo', the original plate 1 may be moved downward. The above-described vertical alignment operation is performed on the three pairs of one-dimensional diffraction grating marks 7a to 7c and 8a to 8c in order to adjust the vertical position of the original plate 1 and the substrate 3 and the inclination with respect to the horizontal plane.

FIG. 11 is a diagram showing a state in which the substrate has moved laterally. Further, FIG. 12 is a diagram showing a positional relationship of real images formed on the light receiving surfaces of the pair of position sensors in FIG. 11. When the substrate 3 moves in the lateral direction and the one-dimensional diffraction grating mark 8 is displaced to the position indicated by reference numeral 8 ′,
Initially, the diffracted lights DBwa and DBwb from the one-dimensional diffraction grating mark 8 follow the position sensor PS along the path indicated by the solid line.
Diffracted light DBw from the one-dimensional diffraction grating mark 8 which reaches wa and PSwb but is displaced to the position indicated by reference numeral 8 ′.
a and DBwb will reach the position sensors PSwa and PSwb along the path indicated by the broken line.

In this case, referring to FIG. 12, even if the substrate 3 moves in the lateral direction, the real images 8Ia and 8Ib move in the same direction by the same amount, so that there is a change in the distance Lo between the real images 8Ia and 8Ib. Does not happen. That is, the real images 8Ia and 8
By measuring the distance L from Ib, it is possible to know the amount of vertical displacement of the substrate 3 regardless of the lateral displacement of the substrate 3. Similarly, by measuring the distance L between the real images 7Ia and 7Ib, it is possible to know the vertical displacement amount of the original 1 regardless of the horizontal displacement of the original 1.

As described above, FIG. 1 shows a positioning device composed of the lateral alignment portion shown in FIG. 2 and the vertical alignment portion shown in FIG. However, the plane mirror 9 in FIG. 2 is replaced with the half mirror 16 in FIG. With this configuration, the diffracted light from the one-dimensional diffraction grating marks 7 and 8 is separated into two via the half mirror 16. Then, the diffracted light portion reflected by the half mirror 16 is guided to the imaging system and the detection system (MSh) of the lateral alignment portion, and the diffracted light portion transmitted through the half mirror 16 is imaged in the vertical alignment portion. System and detection system (MSv). Thus, the half mirror 16 constitutes a beam splitter for splitting the diffracted light from the one-dimensional diffraction grating marks 7 and 8, respectively.

As described above, the alignment apparatus according to the present embodiment has a lateral alignment section for performing lateral alignment between the original 1 and the substrate 3 in the proximity exposure apparatus,
It has a vertical alignment portion for performing vertical alignment between the original 1 and the substrate 3. In this embodiment, the vertical alignment operation is described next to the horizontal alignment operation. However, in the actual alignment step, the vertical alignment between the original 1 and the substrate 3 is performed. After performing the operation, it is advantageous to perform a lateral alignment operation between the master 1 and the substrate 3. This is because the risk of mechanical interference between the original 1 and the substrate 3 can be surely avoided by performing the vertical alignment operation between the original 1 and the substrate 3.

As described above, in this embodiment, the coherent light is obliquely applied to the one-dimensional diffraction grating marks 7 and 8 formed on the original plate 1 and the substrate 3 to form an oblique optical path close to the irradiation optical path. One-dimensional diffraction grating mark 7 generated along
And the real images 7I and 8I of the one-dimensional diffraction grating marks 7 and 8 are formed on the basis of the diffracted light from the first and the second planes 8, and the lateral alignment between the original plate 1 and the substrate 3 Vertical alignment is performed. Therefore, in the proximity exposure apparatus, the original plate 1 and the substrate 3 can be aligned with each other without blocking the exposure optical path. In other words, the present embodiment is a fixed system in which it is not necessary to retract the alignment optical system from the exposure optical path during exposure of the proximity exposure apparatus. Therefore, the original plate 1 and the substrate 3 can be aligned even during exposure, and the processing time of the alignment process and the exposure process can be shortened based on a simple mechanism.

Further, in the present embodiment, lateral alignment and vertical alignment can be performed based on the same alignment mark (one-dimensional diffraction grating marks 7 and 8). Further, since it is not necessary for the alignment optical system to enter the exposure optical path, it is possible to reduce the distance between the alignment marks. Further, it is possible to detect not only whether or not the alignment mark is at a predetermined position, but also the displacement direction of the alignment mark over a wide range. Therefore, in this embodiment, the positioning control is facilitated, and the original plate 1 and the substrate 3 can be quickly positioned.

Further, since the diffraction grating mark is used as the alignment mark and the diffracted light from the diffraction grating mark is used for position detection, it is possible to perform highly accurate alignment without being easily affected by noise due to dust or the like. . Further, by using the one-dimensional diffraction grating marks 7 and 8 having different pitches on the original plate 1 and the substrate 3, the diffracted light from the one-dimensional diffraction grating mark 7 and the diffracted light from the one-dimensional diffraction grating mark 8 are well separated. can do. As a result, it is possible to detect the position shift signal relating to the original 1 and the position shift signal relating to the substrate 3 separately without interfering with each other.
It is possible to completely independently control the position of the substrate 3 and the substrate 3. Further, since the positional deviation can be detected by the optical system and the electric system having a simple structure, it is possible to reduce the size of the entire alignment device.

In the above-mentioned embodiment, the present invention is applied to the alignment of the original plate and the substrate in the proximity exposure apparatus, but the invention is not limited to this, and it should be generally arranged in parallel with each other. The present invention can also be applied to the positional alignment of a pair of substrates.

As described above, in the present embodiment, the coherent light is obliquely applied to the diffraction grating marks formed on the pair of substrates, and the diffraction generated along the oblique optical path close to the irradiation optical path. A real image of the mark is formed based on the light, and the lateral alignment and the vertical alignment of the pair of substrates are performed based on these real images. Therefore, even when applied to, for example, a proximity exposure apparatus, the original plate and the substrate can be aligned in a fixed manner without blocking the exposure optical path.

[0044]

As described above, according to the present invention, since the illumination system and the imaging system are arranged outside the exposure region and on the same side, the diffraction grating mark can be observed even during the exposure process of the semiconductor. Further, since the optical axis of the imaging optical system and the normal line of the first substrate are arranged in parallel, the diffraction grating mark can be detected with high accuracy.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a configuration of an alignment device according to an embodiment of the present invention.

FIG. 2 is a diagram schematically showing a configuration of a lateral alignment section of the alignment apparatus according to the present embodiment.

FIG. 3 is a diagram schematically showing a configuration of an alignment mark formed on an original plate and a substrate of this embodiment.

FIG. 4 is a diagram illustrating diffracted light generated from a one-dimensional diffraction grating mark formed on an original plate and a substrate.

FIG. 5 is a diagram showing a positional relationship between a pair of one-dimensional diffraction grating marks formed on an original plate and a substrate and a positional relationship between a pair of real images formed on a four-divided position detection element.

FIG. 6 is a signal S when the one-dimensional diffraction grating mark 7 or 8 (and thus the original plate 1 or the substrate 3) is moved in the lateral direction.
It is a figure which shows the mode of change of m or Sw.

FIG. 7 is a diagram schematically showing a configuration of a vertical alignment unit of the alignment device according to the present embodiment.

FIG. 8 shows four position sensors PSm in FIG. 7 (b).
It is the figure which looked at a, PSmb, PSwa, and PSwb from right above in the figure.

FIG. 9 is a diagram illustrating the principle of the vertical position detection method according to the present invention.

10 is a diagram showing a positional relationship of real images formed on the light receiving surfaces of the pair of position sensors in FIG.

FIG. 11 is a diagram showing a state in which the substrate has moved laterally.

12 is a diagram showing a positional relationship of real images formed on the light receiving surfaces of the pair of position sensors in FIG.

[Explanation of symbols]

1 original 2 Original pattern 3 substrates 4 light sources 5,6,11,15 Objective lens 7,8 One-dimensional diffraction grating mark 9 plane mirror 10,14 Triangular prism 12 Four-division position detection element 13 Opening member 16 half mirror

Continued front page    F term (reference) 2F065 AA03 AA06 AA07 AA14 AA20                       BB02 BB27 CC20 FF01 FF48                       GG05 GG06 GG12 GG22 HH03                       HH12 JJ01 JJ16 JJ22 LL08                       LL12 LL42                 5F046 BA02 EA07 EB01 EB02 ED01                       FA05 FA10 FB09 FB12

Claims (7)

[Claims] 1. An alignment apparatus for a proximity exposure apparatus, which aligns a first substrate and a second substrate, which are arranged in parallel and close to each other, including an illumination optical system and is formed on the first substrate. The first diffraction grating mark and the second diffraction grating mark formed on the second substrate with an illumination system for illuminating the coherent light, and an image forming optical system.
An imaging system for detecting a diffraction image from the diffraction grating mark and a diffraction image from the second diffraction grating mark is provided, and the illumination system and the imaging system are arranged outside the exposure area and on the same side. Further, the alignment device is characterized in that the optical axis of the imaging optical system and the normal line of the first substrate are arranged in parallel. 2. The illumination-light exit-side objective lens of the illumination optical system and the diffracted-light entrance-side objective lens of the imaging optical system are common optical systems, and the common optical system has an optical axis. The alignment device according to claim 1, wherein the alignment line is arranged parallel to a normal line of the first substrate. 3. The common optical system comprises a semicircular lens obtained by cutting a part of a circular lens, or a cylindrical lens obtained by cutting a part of a cylindrical lens in the refraction direction. The alignment device described. 4. The first diffraction grating mark and the second diffraction grating mark have substantially different grating pitches, and the imaging system includes the diffracted light from the first diffraction grating mark and the first diffraction grating mark. The alignment device according to any one of claims 1 to 3, further comprising a deflecting member for guiding the diffracted light from the two diffraction grating marks along substantially different directions. 5. The detection system includes a first split light receiving element for detecting a diffraction image of the first diffraction grating mark and a second split light receiving element for detecting a diffraction image of the second diffraction grating mark. The position of the first substrate and the second substrate along the in-plane direction of the first substrate based on the output of the first divided light receiving element and the output of the second divided light receiving element. The alignment device according to claim 1, wherein a displacement is measured. 6. The image forming system includes a dividing member that divides the diffracted light from the first diffraction grating mark and the diffracted light from the second diffraction grating mark symmetrically with respect to the longitudinal direction of the mark, The first substrate based on the positional relationship between one mark image formed by one diffracted light beam from the first diffraction grating mark divided by the dividing member and the other mark image formed by the other diffracted light beam. The positional deviation of the first substrate along the normal direction of the first diffraction grating mark, and one mark image formed by one diffracted light beam from the second diffraction grating mark divided by the dividing member and the other diffracted light beam. 6. The positional deviation of the second substrate along the normal direction is measured based on the positional relationship with the other mark image formed by the method according to claim 1. Position To equipment. 7. The imaging system has a beam splitter for splitting the diffracted light from the first diffraction grating mark and the diffracted light from the second diffraction grating mark, respectively, and is split by the beam splitter. Based on the one diffracted light from the first diffraction grating mark and the one diffracted light from the second diffraction grating mark, the first substrate and the second substrate along the in-plane direction of the first substrate. And a method for measuring the first substrate based on the other diffracted light from the first diffraction grating mark and the other diffracted light from the second diffraction grating mark, which are divided by the beam splitter. 7. The alignment device according to claim 1, wherein a positional deviation of the first substrate and the second substrate along a line direction is measured.