Exposure apparatus

Abstract

To provide a technique capable of efficiently and easily measuring a misalignment of an optical axis.SOLUTION: An exposure apparatus comprises a stage 2, a stage moving mechanism, a laser light source, a spatial light modulator 510, an illumination optical system 535, a projection optical system 511, an imaging element 71 and an optical axis measurement part. The stage supports a substrate W, the stage moving mechanism moves the stage in Y direction, the spatial light modulator spatially modulates a laser beam from the laser light source, the illumination optical system images the laser beam from the laser light source to the spatial light modulator, the projection optical system images the laser beam modulated by the spatial light modulator on an exposure surface of the substrate, the imaging element detects the laser beam emitted from the projection optical system on an observation plane positioned further than the exposure surface to the projection optical system, and the optical axis measurement part measures a misalignment amount of an optical axis of the laser beam by using the position of the laser beam detected by the imaging element.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The subject matter disclosed in this specification relates to an exposure apparatus.

Background Art

[0002] As a method of forming a pattern on a substrate such as a semiconductor wafer or a glass substrate, an exposure apparatus (direct writing apparatus) that performs direct writing by light irradiation is known. In this type of exposure apparatus, a substrate on which a photosensitive layer such as a resist is formed is held by a stage, and the stage is moved in the main scanning direction. Then, depending on the position of the stage in the main scanning direction, pattern light is emitted from an optical head, and a predetermined pattern is drawn on the photosensitive layer. In addition, a spatial light modulator is used to form pattern light corresponding to the pattern. A spatial light modulator such as a GLV (Grating Light Valve, a registered trademark of Silicon Light Machines, USA) or a DMD (Digital Mirror Device) can control the on / off of beams of thousands of pixels.

[0003] The optical head in the exposure apparatus includes a light source, an illumination optical system, a spatial light modulator, a projection optical system, and a control unit that controls the spatial light modulator. In order to expose submicron L / S (Line and Space), since the mirror image of the spatial light modulator also needs to be reduced to submicron size, the magnification of the projection lens that reduces and projects the mirror image increases. Then, the stability of the optical system, particularly the angular change of the optical axis, may become a problem.

[0004] That is, according to the formula of the magnification of the optical system, for example, when the angular change incident on a reduction projection lens of ×1 / 10 times is Θ degrees, the optical axis tilts by 10Θ degrees multiplied by the reciprocal of the magnification on the exposure surface. When the optical axis tilts on the image plane, a bias occurs in the light amount distribution in the resist, resulting in a tilted resist shape after development, and problems may occur in subsequent processes. Since measures to improve the stability of the optical system also have limitations in terms of cost-effectiveness, it is desirable to prevent exposure defects by monitoring the change of the optical axis.

[0005] As a method for detecting the inclination of the optical axis, for example, direct observation of the beam on the exposure surface has been performed. Specifically, an observation device for magnifying and observing the beam, which is installed on the stage, is arranged directly below the projection optical system, and the beam is imaged while moving the observation device (or the objective lens of the projection optical system) in a direction parallel to the ideal optical axis. When the optical axis is not inclined, even if the observation device is moved, the position of the beam in the horizontal plane does not change. On the other hand, when the optical axis is inclined, if the observation device is moved in the optical axis direction, the position of the beam moves in the horizontal plane according to the inclination of the beam. Therefore, it is possible to calculate the inclination of the optical axis by using the amount of movement of the observation device and the amount of movement of the beam in the horizontal plane. Further, when the inclination exceeds the allowable range, the inclination of the optical axis of the light incident on the projection optical system is normalized by adjusting the angle of the mirror installed between the illumination optical system and the spatial light modulation element (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, when using a conventional observation device, each time the inclination of the optical axis is detected, it is necessary to move the observation device up and down, which takes time for measurement and thereby reduces productivity. In addition, in order to observe a beam narrowed down to sub-microns, a high-resolution (high magnification) observation device is required, resulting in a problem of high measurement cost.

[0008] An object of the present invention is to provide a technique capable of efficiently and at low cost measuring the deviation of the optical axis.

Means for Solving the Problems

[0009] To solve the above problems, a first aspect is an exposure apparatus, comprising: a stage for supporting an object; a stage moving mechanism for moving the stage in a predetermined moving direction; a light source for emitting laser light; a spatial modulator for spatially modulating the laser light from the light source; an illumination optical system for imaging the laser light from the light source onto the spatial modulator; a projection optical system for imaging the laser light modulated by the spatial modulator onto the exposure surface of the object; an optical sensor for detecting the laser light emitted from the projection optical system on an observation surface located farther from the projection optical system than the exposure surface; and an optical axis measurement unit for measuring a deviation amount of the optical axis of the laser light based on the position of the laser light detected by the optical sensor.

[0010] A second aspect is the exposure apparatus according to the first aspect, further comprising: the optical axis measurement unit for obtaining the position of the laser light using the light amount distribution detected by the optical sensor.

[0011] A third aspect is the exposure apparatus according to the first aspect or the second aspect, further comprising: a determination unit for determining whether or not the deviation amount measured by the optical axis measurement unit exceeds a threshold value.

[0012] A fourth aspect is the exposure apparatus according to the first aspect or the second aspect, further comprising: a mirror for reflecting the laser light from the illumination optical system and making it incident on the spatial modulator; and an angle adjustment unit for adjusting the angle of the mirror.

[0013] A fifth aspect is the exposure apparatus according to the first aspect or the second aspect, wherein the spatial light modulator has a diffractive modulation element.

[0014] A sixth aspect is the exposure apparatus according to the fourth aspect, wherein the diffractive modulation element has a plurality of reflecting surfaces arranged in a predetermined array direction, and each of the reflecting surfaces has a fixed reflecting surface and a movable reflecting surface that can move up and down with respect to the fixed reflecting surface.

[0015] Aspect 7 is the exposure apparatus of Aspect 5, wherein the optical sensor is capable of detecting the zeroth-order diffracted light and the ±first-order diffracted light emitted from the diffractive modulation element, and the deviation amount calculation unit calculates the deviation amount using the position of any one of the zeroth-order diffracted light and the ±first-order diffracted light detected by the optical sensor.

[0016] Aspect 8 is the exposure apparatus of Aspect 7, wherein the projection optical system has a diaphragm, and the optical axis measurement unit identifies the contour of the diaphragm based on the shapes of the zeroth-order diffracted light and the ±first-order diffracted light detected by the optical sensor, and calculates the deviation amount using the position of any one of the zeroth-order diffracted light and the ±first-order diffracted light with respect to the contour.

[0017] Aspect 9 is the exposure apparatus of Aspect 1 or Aspect 2, wherein the stage has a support surface for supporting the object, and the optical sensor is disposed inside the outer edge of the support surface.

Advantages of the Invention

[0018] According to the exposure apparatus of Aspect 1, the deviation amount of the optical axis can be efficiently measured without moving the optical sensor in the optical axis direction. In addition, the light imaged on the exposure surface by the projection optical system is detected in an enlarged state on the observation surface. Thereby, since the resolution (magnification) of the observation device can be kept low, the measurement cost of the optical axis deviation can be reduced.

[0019] According to the exposure apparatus of Aspect 2, the displacement of the position of the laser light can be appropriately acquired based on the light amount distribution.

[0020] According to the exposure apparatus of Aspect 3, it is possible to appropriately determine whether the optical axis deviation exceeds the allowable range.

[0021] According to the exposure apparatus of Aspect 4, the optical axis deviation can be easily corrected by adjusting the angle of the mirror.

[0022] According to the exposure apparatus of Aspect 5, the optical axis deviation can be measured by detecting the diffracted light.

[0023] According to the exposure apparatus of the seventh aspect, by measuring the optical axis deviation using a plurality of diffracted lights, the measurement accuracy can be improved as compared with the case of measuring the optical axis deviation using only one diffracted light.

[0024] According to the exposure apparatus of the eighth aspect, even when the position of the optical sensor is displaced, the amount of deviation of the optical axis can be appropriately measured.

[0025] According to the exposure apparatus of the ninth aspect, since it is arranged near the object, for example, even during the exposure process, the amount of deviation of the optical axis can be efficiently measured.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0027] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the components described in this embodiment are merely examples, and are not intended to limit the scope of the present invention thereto. In the drawings, for ease of understanding, the dimensions and numbers of each part may be exaggerated or simplified as necessary.

[0028] <1. Embodiment> FIG. 1 is a perspective view showing an exposure apparatus 100 according to an embodiment. The exposure apparatus 100 is a substrate processing apparatus for processing a substrate W, and is an apparatus that irradiates light onto the upper surface of a substrate W on which a layer of a photosensitive material such as a resist (photosensitive layer W1) is formed to draw a pattern. The substrate W is, for example, a semiconductor substrate, a printed circuit board, a substrate for a color filter, a glass substrate for a flat panel display used in a liquid crystal display device or a plasma display device, or a substrate for an optical disk. The exposure apparatus 100 includes a base 1, a stage 2, a stage moving mechanism 3, a gantry 4, an exposure unit 5, an observation unit 7, and a control unit 9.

[0029] The base 1 has a rectangular shape in a top view. The base 1 supports the stage 2, the stage moving mechanism 3, and the gantry 4 from below.

[0030] The stage 2 has an upper surface 2S as a support surface for supporting the substrate W. In a top view of the upper surface 2S viewed from above, the upper surface 2S is rectangular (here, rectangular). The upper surface 2S is a horizontal plane parallel to the X direction and the Y direction. The substrate W is placed on the upper surface 2S in a horizontal posture. A plurality of suction holes are formed in the upper surface 2S. The stage 2 can fix the substrate W to the upper surface 2S by applying a negative pressure (suction pressure) to the suction holes. Note that a chuck for gripping the periphery of the substrate W may be provided on the upper surface 2S, and the substrate W may be fixed to the upper surface 2S by the chuck.

[0031] The stage moving mechanism 3 moves the stage 2 in the main scanning direction (Y direction), the sub-scanning direction (X direction), and the rotation direction (rotation direction around the Z axis (θ direction)). The stage moving mechanism 3 includes a support plate 31, a sub-scanning mechanism 32, a base plate 33, a main scanning mechanism, and a rotation mechanism 35.

[0032] The support plate 31 is disposed below the stage 2 and rotatably supports the stage 2. The base plate 33 is disposed below the support plate 31 and supports the support plate 31 and the sub-scanning mechanism 32. The sub-scanning mechanism 32 moves the support plate 31 in the X direction, which is the sub-scanning direction, with respect to the base plate 33. The main-scanning mechanism 34 moves the base plate 33 in the Y direction, which is the main-scanning direction, with respect to the base 1. When the base plate 33 moves in the Y direction, the stage 2 moves in the Y direction. The sub-scanning mechanism 32 and the main-scanning mechanism 34 are constituted by, for example, a linear motor mechanism including a linear motor and a guide, or a ball screw mechanism including a rotary motor, a ball screw, and a guide. The rotation mechanism 35 is provided on the support plate 31 and rotates the stage 2 about the rotation axis A extending in the Z direction. The sub-scanning mechanism 32, the main-scanning mechanism 34, and the rotation mechanism 35 operate based on a control command from the control unit 9.

[0033] The exposure unit 5 has one or a plurality of exposure heads 51. In this example, five exposure heads 51 are arranged along the X direction. Each exposure head 51 has a spatial light modulator 510. The spatial light modulator 510 spatially modulates the laser light based on the strip data corresponding to the drawing pattern.

[0034] The exposure unit 5 has a light irradiation unit 53. The light irradiation unit 53 irradiates the exposure head 51 with laser light. The light irradiation unit 53 has a laser drive unit 531, a laser light source 533 (light source), and an illumination optical system 535. By the operation of the laser drive unit 531, the laser light source 533 emits laser light to the illumination optical system 535. The illumination optical system 535 performs magnification change of the laser light incident from the laser light source 533 and uniformization of the light quantity distribution, etc. The laser light emitted from the illumination optical system 535 is irradiated to the spatial light modulator 510 of each exposure head 51.

[0035] The spatial light modulator 510 spatially modulates the laser light irradiated from the light irradiation unit 53 in units of channels, and reflects the necessary light that contributes to the drawing of the pattern and the unnecessary light that does not contribute to the drawing of the pattern in different directions from each other. Note that spatially modulating light means changing the spatial distribution (amplitude, phase, polarization, etc.) of the light. The exposure head 51 projects the modulated laser light onto the substrate W that moves directly below the exposure head 51. As a result, the drawing pattern is exposed on the unprocessed substrate W.

[0036] FIG. 2 is a diagram showing the configuration of the exposure unit 5. As shown in FIG. 2, the exposure head 51 has a projection optical system 511. The projection optical system 511 forms an image of the laser light spatially modulated by the spatial light modulator 510 on the exposure surface ES. The exposure surface ES is, for example, the surface of the substrate W (or the photosensitive layer W1) that is the object.

[0037] FIG. 3 is a cross-sectional view showing the spatial light modulator 510. Specifically, the spatial light modulator 510 of the present embodiment is a GLV, which is a type of diffraction-type modulation element. As shown in FIG. 3, the spatial light modulator 510 has a bottom electrode 61, a plurality of fixed ribbons 63, and a plurality of movable ribbons 65. The bottom electrode 61 has, for example, a flat plate shape. The fixed ribbons 63 and the movable ribbons 65 are alternately arranged in one direction (X direction) on the bottom electrode 61. The lower surface of each fixed ribbon 63 and the lower surface of each movable ribbon 65 face the upper surface of the bottom electrode 61, respectively. The upper surface of the fixed ribbon 63 is a fixed reflection surface 63S, and the upper surface of the movable ribbon 65 is a movable reflection surface 65S. The fixed reflection surface 63S and the movable reflection surface 65S are finished to be flat. The plurality of fixed reflection surfaces 63S and the plurality of movable reflection surfaces 65S are the condensing surfaces of the spatial light modulator 510.

[0038] The fixed reflecting surface 63S is fixed at a position separated from the bottom electrode 61 by a predetermined distance. Also, the movable reflecting surface 65S is provided so as to be movable in a direction approaching and separating from the bottom electrode 61 in accordance with the applied voltage (driving voltage). That is, the movable reflecting surface 65S is movable in a direction perpendicular to the fixed reflecting surface 63S with respect to the fixed reflecting surface 63S.

[0039] The displacement amount of the movable reflecting surface 65S is adjusted in accordance with the magnitude of the potential difference generated between the movable ribbon 65 and the bottom electrode 61 by the driving voltage. For example, as shown on the left side of FIG. 3, when the height difference d between the fixed reflecting surface 63S and the movable reflecting surface 65S is zero, the light reflected by the fixed reflecting surface 63S and the light reflected by the movable reflecting surface 65S are in the same phase. Therefore, these lights are emitted from the spatial light modulator 510 as the specular reflection light Lr (zero-order diffracted light).

[0040] When the wavelength of the incident light Li is λ, when the optical path difference (= 2d) between the light reflected by the fixed reflecting surface 63S and the light reflected by the movable reflecting surface 65S is an integral multiple of the wavelength λ (= n × λ, where n is an integer equal to or greater than zero), the light reflected by the fixed reflecting surface 63S and the light reflected by the movable reflecting surface 65S are in the same phase. That is, the specular reflection light Lr (zero-order diffracted light) is emitted from the spatial light modulator 510.

[0041] Also, as shown in the center of FIG. 3, when the optical path difference (= 2d) between the light reflected by the fixed reflecting surface 63S and the light reflected by the movable reflecting surface 65S is an odd multiple of the half wavelength λ / 2, the light reflected by the fixed reflecting surface 63S and the light reflected by the movable reflecting surface 65S are in opposite phases and cancel each other out. For this reason, no reflected light in the vertical direction is emitted from the spatial light modulator 510, and diffracted light in the oblique direction, that is, diffracted light of ±1st order or higher (scattered light Ld) is emitted.

[0042] Also, as shown on the right side of FIG. 3, when the optical path difference (= 2d) between the light reflected by the fixed reflecting surface 63S and the light reflected by the movable reflecting surface 65S is different from the wavelength λ and also different from the half wavelength λ / 2, a part of the incident light Li is emitted as the specularly reflected light Lr, and the rest is emitted obliquely as diffraction light (scattered light Ld) of ±1st order or higher. That is, depending on the magnitude of the height difference d, the specularly reflected light Lr with an intensity weaker than that of the incident light Li is emitted from the spatial light modulator 510. Thus, in the spatial light modulator 510, it is possible to adjust the intensity of the specularly reflected light Lr (or the intensity of the scattered light Ld) by changing the drive voltage.

[0043] The exposure apparatus 100 performs drawing by irradiating the substrate W with the 0th order diffraction light emitted from the spatial light modulator 510. Also, the diffraction light of ±1st order or higher is blocked by the aperture 511a (see FIG. 3) provided in the projection optical system 511. That is, when exposure is performed, the diffraction light of ±1st order or higher does not exit from the projection optical system 511.

[0044] FIG. 4 is a side view schematically showing the exposure head 51 and the observation unit 7. As shown in FIG. 4, the exposure head 51 further includes a mirror 513 and an angle adjustment unit 515. The mirror 513 reflects the laser light emitted from the illumination optical system 535 and makes it incident on the spatial light modulator 510. The angle adjustment unit 515 is a device that adjusts the angle of the mirror 513. For example, when the deviation of the optical axis of the laser light exceeds the allowable range, the angle of the mirror 513 is adjusted by the angle adjustment unit 515 to normalize this. The angle adjustment unit 515 has a moving member that individually moves a plurality of locations (for example, three locations) of the mirror 513. By pushing and pulling the mirror 513 with the moving member, the angle of the mirror 513 is changed. The angle adjustment unit 515 may operate in response to a control command from the control unit 9. In this case, several micromotors for moving the moving member are appropriately provided in the angle adjustment unit 515. Further, the control unit 9 may output a control command for adjusting the angle of the mirror 513 based on the amount of deviation of the optical axis measured by the optical axis measurement unit 97 described later. Note that the angle adjustment unit 515 may be operated by a human hand. In this case, a manipulator for operating the member that moves the mirror 513 is appropriately provided in the angle adjustment unit 515.

[0045] The observation unit 7 is a device for observing the deviation of the laser light emitted from the projection optical system 511. The observation unit 7 is disposed on the upper surface 2S of the stage 2. The observation unit 7 has an imaging element 71. The imaging element 71 is an image sensor composed of a CCD (Charge-Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), etc. The imaging element 71 corresponds to a "light sensor" that detects the light emitted from the projection optical system 511. Also, the observation surface OS of the observation unit 7 corresponds to the imaging surface of the imaging element 71. The observation surface OS is located farther from the projection optical system 511 than the exposure surface ES. That is, the observation surface OS is located below the exposure surface ES. The observation unit 7 may have an optical system that forms an image of the incident light on the imaging element 71 (observation surface OS).

[0046] FIG. 5 is a block diagram showing the configuration of the control unit 9 shown in FIG. 1. The control unit 9 includes a processor such as a CPU (Central Processing Unit) and a storage unit 90 electrically connected to the processor. The storage unit 90 is composed of a main storage device such as a RAM (Random Access Memory) and an auxiliary storage device such as a hard disk. The storage unit 90 stores the program P. The program P may be provided to the control unit 9 via a magnetic medium, an optical disk such as a DVD, or a semiconductor memory such as a USB (Universal Serial Bus) flash drive. By the processor executing the program P, the control unit 9 functions as an irradiation control unit 91, a stage control unit 93, a drawing control unit 95, an optical axis measurement unit 97, and a determination unit 98. Note that a part of the functions of the control unit 9 may be realized by a dedicated circuit (for example, an application specific integrated circuit (ASIC)).

[0047] The irradiation control unit 91 controls the laser light source 533 of the light irradiation unit 53 to cause the light irradiation unit 53 to emit laser light (line beam light) toward the exposure head 51. The stage control unit 93 controls the stage moving mechanism 3 to move the stage 2 in the Y direction, which is the main scanning direction, and the X direction, which is the sub-scanning direction, with respect to the exposure head 51. The drawing control unit 95 controls the spatial light modulator 510 of the exposure head 51 using the drawing recipe stored in the storage unit 90 and the position information of the stage 2. More specifically, the drawing control unit 95 controls the drive voltage applied to each channel of the spatial light modulator 510 to modulate the line beam light so as to correspond to the drawing pattern. Thereby, pattern light corresponding to the drawing pattern is formed, and the pattern light is emitted from the exposure head 51.

[0048] The drawing recipe describes, for example, pattern data indicating a drawing pattern to be formed on the substrate W and various conditions for drawing (such as the amount of light emitted from the exposure unit 5, the moving speed of the stage 2, etc.) in a predetermined data format. The pattern data is, for example, data obtained by rasterizing CAD data generated using CAD (Computer Aided Design), and the position information on the substrate W where light is to be irradiated is recorded in pixel units.

[0049] The optical axis measurement unit 97 measures the deviation amount of the optical axis (hereinafter simply referred to as "optical axis") in the laser light emitted from the projection optical system. Specifically, the optical axis measurement unit 97 measures the deviation amount of the optical axis using the observation image captured by the imaging element 71 of the observation unit 7. Each pixel of the observation image captured by the imaging element 71 has a luminance value indicating the intensity (amount of light) of the incident light. Therefore, the observation image has information indicating the incident position where the laser light is incident on the observation surface OS and the amount of light of the laser light. As will be described later, the optical axis measurement unit 97 measures the deviation amount of the optical axis using the position of the laser light detected by the imaging element 71 and the amount of light of the laser light (specifically, the light amount distribution).

[0050] The determination unit 98 determines whether or not the deviation amount of the optical axis measured by the optical axis measurement unit 97 exceeds a predetermined threshold value. The determination unit 98 causes the determination result to be displayed on the display 99 connected to the control unit 9. For example, when the deviation amount of the optical axis exceeds a predetermined threshold value, the determination unit 98 causes a predetermined warning image to be displayed on the display 99. Thereby, it is possible to notify the user that the deviation amount of the optical axis has exceeded the allowable range. Note that the determination unit 98 may output the determination result to an output device different from the display 99. Examples of the output device include a lamp such as a warning lamp, a speaker that emits a warning sound, or a printer.

[0051] Further, the drawing control unit 95 adjusts the angle of the mirror 513 by controlling the angle adjustment unit 515. For example, when the determination unit 98 determines that the deviation amount of the optical axis exceeds a predetermined threshold value, the drawing control unit 95 may automatically control the angle adjustment unit 515 according to the deviation amount of the optical axis measured by the optical axis measurement unit 97. Further, the drawing control unit 95 may control the angle adjustment unit 515 according to an input command from the user.

[0052] FIG. 6 is a diagram schematically showing the movement of the stage 2 when exposing the photosensitive layer W1 of the substrate W. When exposing the photosensitive layer W1, the stage 2 is moved in the Y direction to perform a main scanning movement of moving the substrate W supported by the stage 2 in the Y direction (main scanning direction) with respect to the exposure head 51. Then, the exposure head 51 irradiates the substrate W moving in the Y direction with pattern light. Further, after the main scanning movement, a sub-scanning movement of moving the substrate W in the X direction is performed by moving the stage 2 in one direction in the X direction by the width of the pattern light. The exposure apparatus 100 exposes the entire photosensitive layer W1 of the substrate W by repeating such main scanning movement and sub-scanning movement.

[0053] As shown in FIG. 6, the upper surface 2S of the stage 2 includes an exposure region A1 and two acceleration / deceleration regions A2, A2. The exposure region A1 is a region where the exposure head 51 performs exposure in the main scanning movement, specifically, a region where the photosensitive layer W1 of the substrate W is disposed. The acceleration / deceleration regions A2 are located on the +Y side and -Y side of the exposure region A1. The acceleration / deceleration regions A2 are regions where the exposure head 51 does not perform exposure. During the main scanning movement, while the exposure head 51 is facing the acceleration / deceleration region A2, the stage 2 is accelerated or decelerated.

[0054] For example, as shown in FIG. 6, assume a case where the main scanning movement is started from a state where the exposure head 51 is positioned away from the stage 2 in the +Y direction. In this case, while the exposure head 51 passes over the acceleration / deceleration region A2 on the +Y side, the stage 2 is accelerated to a predetermined speed. Also, while the exposure head 51 passes over the exposure region A1, the stage 2 is moved at a constant speed. Then, while the exposure head 51 passes over the acceleration / deceleration region A2 on the -Y side, the stage 2 is decelerated. After that, the stage 2 is stopped.

[0055] As shown in FIG. 6, the observation unit 7 is disposed in the acceleration / deceleration region A2 on the upper surface 2S of the stage 2. Also, in the X direction, the observation unit 7 is positioned inside the exposure region A1. That is, the observation unit 7 is positioned on the +X side from the -X side end of the exposure region A1 and on the -X side from the +X side end of the exposure region A1. By disposing the observation unit 7 in the acceleration / deceleration region A2 of the stage 2, it becomes possible to measure the amount of deviation of the optical axis during the main scanning movement. For this reason, the amount of deviation of the optical axis can be measured efficiently.

[0056] <Measurement of the amount of deviation of the optical axis> FIG. 7 is a diagram showing the optical path of the laser light from the spatial light modulator 510 to the observation surface OS. FIG. 7(A) shows the optical path when there is no deviation of the optical axis, and FIG. 7(B) shows the optical path when the optical axis is deviated.

[0057] In the following description, in the spatial light modulator 510, the direction in which the fixed ribbon 63 and the movable ribbon 65 (channels) are arranged is defined as the x direction. Also, the direction orthogonal to the x direction and parallel to the reflection surfaces (the fixed reflection surface 63S and the movable reflection surface 65S) is defined as the y direction. The x direction coincides with the sub-scanning direction X direction.

[0058] In FIG. 7, the optical paths of the laser light emitted from the +x side end portion of the spatial light modulator 510, the laser light emitted from the center in the x direction, and the laser light emitted from the -x side end portion among the light emitted from the spatial light modulator 510 are illustrated.

[0059] When measuring the deviation amount of the optical axis, the spatial light modulator 510 is controlled so that the zeroth-order diffracted light and the ±first-order diffracted light emitted from the spatial light modulator 510 pass through the aperture 511a and enter the observation plane OS. Note that the emission directions of the ±first-order diffracted lights can be controlled by adjusting the positions of the respective movable reflecting surfaces 65S in the spatial light modulator 510.

[0060] On the optical path, the observation plane OS is located farther from the projection optical system 511 (more specifically, the objective lens of the projection optical system 511) than the exposure plane ES. And the projection optical system 511 is set to form an image of the laser light on the exposure plane ES. For this reason, the zeroth-order diffracted light and the ±first-order diffracted lights are focused at the same position on the exposure plane ES and travel away from each other. For this reason, on the observation plane OS, the zeroth-order diffracted light and the ±first-order diffracted lights enter the observation plane OS at different positions. More specifically, the -first-order diffracted light travels away from the zeroth-order diffracted light in the +x direction, and the +first-order diffracted light travels away from the zeroth-order diffracted light in the -x direction. For this reason, on the observation plane OS, the -first-order diffracted light enters a position separated from the zeroth-order diffracted light in the +x direction, and the +first-order diffracted light enters a position separated from the zeroth-order diffracted light in the -x direction.

[0061] In the observation image 8a obtained by the imaging element 71 of the observation unit 7, the zeroth-order diffracted light, the +first-order diffracted light, and the -first-order diffracted light appear as strip-shaped bands 81, 82, 83 (hereinafter referred to as "bands 81 to 83").

[0062] Also, the laser light emitted from the spatial light modulator 510 shows a light quantity distribution (intensity distribution) along a Gaussian distribution in the y direction. The light quantity distribution in the y direction indicated by the luminance of the bands 81 to 83 of the observation image 8A also becomes a distribution along a Gaussian distribution. The light quantity distribution LD1 shown in FIG. 7(A) shows the light quantity distribution of the band 81.

[0063] When there is a deviation in the optical axis, the incident positions of the zeroth-order diffracted light and the ±first-order diffracted light with respect to the observation plane OS change. For example, in the example shown in FIG. 7(B), the optical axis of the laser light incident on the spatial light modulator 510 is tilted, so that the optical axis of the laser light output from the projection optical system 511 is deviated. When the optical axis is deviated, in the inspection observation image 8b acquired by the image sensor 71 of the observation unit 7, the bands 81 to 83 are displaced from the normal positions (the positions in the observation image 8A). That is, when the optical axis is deviated in the x direction, the positions of the bands 81 to 83 in the x direction (hereinafter referred to as "x positions") change, and when the optical axis is deviated in the y direction, the positions of the bands 81 to 83 in the y direction (hereinafter referred to as "y positions") change. Therefore, the optical axis measurement unit 97 detects at least one of the x positions and y positions of the bands 81 to 83, and measures the displacement of the detected x position and y position from the normal state as the deviation amount of the optical axis.

[0064] In the following description, the case of detecting the x position and y position of the band 81 of the zeroth-order diffracted light will be described. However, the x positions and y positions of the other bands 82 and 83 can be detected in the same manner as the x position and y position of the band 81.

[0065] First, the optical axis measurement unit 97 applies known image processing such as edge extraction and pattern recognition using the reference observation image 8A to obtain the x position and y position of the band 81. For example, for the x position, both ends of the band 81 in the x direction may be detected, and the intermediate position between the two ends may be used as the x position. Similarly, for the y position, both ends in the y direction may be detected, and the intermediate position between the two ends may be used as the y position. However, for the y position, it may be obtained based on the light amount distribution LD1 along the Gaussian distribution. For example, the optical axis measurement unit 97 may specify the position where the light amount is maximum (peak) in the light amount distribution LD1, and use that position as the y position of the band 81. When the optical axis measurement unit 97 obtains the x position and y position of the band 81 using the observation image 8A, it stores them in the storage unit 90 as the reference x position and reference y position. The reference x position and reference y position are used when inspecting the deviation of the optical axis.

[0066] When actually inspecting the deviation of the optical axis, as shown in FIG. 7(B), the optical axis measurement unit 97 acquires an observation image 8B for inspection by imaging the zero-order diffracted light and the ± first-order diffracted light with the observation unit 7. Then, the optical axis measurement unit 97 acquires the x position and the y position of the band 81 using the observation image 8B. Then, the optical axis measurement unit 97 obtains the displacement Δx of the acquired x position from the reference x position and the displacement Δy of the acquired y position from the reference y position, respectively.

[0067] For example, in the case of the observation image 8B, the light quantity distribution LD3 in the y direction in the band 81 is shifted in the -y direction from the reference light quantity distribution LD1, and the peak is also shifted in the -y direction. The magnitude and direction of this shift are acquired as the displacement Δy.

[0068] When the displacement Δx and the displacement Δy exceed the threshold value, an image indicating that the deviation amount of the optical axis exceeds the allowable range is displayed on the display 99 by the determination unit 98. Also, according to the displacement Δx and the displacement Δy, the angle of the mirror 513 is adjusted by the angle adjustment unit 515.

[0069] In some cases, a part of the zero-order diffracted light and the ± first-order diffracted light may be blocked by the aperture 511a of the projection optical system 511. In this way, when a part of the diffracted light is blocked, as shown in FIGS. 7(A) and 7(B), one end or both ends in the y direction of any of the bands 81 to 83 have a shape cut out by the circular contour 511b along the aperture 511a. In this case, it is difficult to specify the y position only from the shapes of the bands 81 to 83. Therefore, by using the light quantity distributions LD1 and LD3 in the y direction, the y positions of the respective diffracted lights can be specified without being affected by the aperture 511a.

[0070] As described above, by measuring the displacement of the position on the observation surface OS of the diffracted light, which is laser light, the deviation of the optical axis can be measured. In this case, since it is not necessary to move the observation surface OS up and down, the deviation of the optical axis can be measured efficiently. Further, by observing the laser light on the observation surface OS that is farther from the projection optical system 511 than the exposure surface ES, the laser light can be observed after being enlarged. As a result, a high-resolution device that was required when observing the laser light on the exposure surface ES becomes unnecessary, and thus the deviation of the optical axis can be measured at low cost.

[0071] Note that the optical axis measurement unit 97 may specify the circular contour 511b by extracting the edges of the bands 81 to 83 in the observation images 8A and 8B. Then, the optical axis measurement unit 97 may acquire the x position and the y position of the band 81 with respect to the specified contour 511b. For example, if the position of the imaging device 71 is deviated from the predetermined position due to long-term use or the like, the incident position of each diffracted light with respect to the imaging device is deviated, and thus there is a possibility that it may be erroneously determined that the optical axis is deviated. Therefore, by using the contour 511b of the aperture 511a as a reference, even when the position of the imaging device 71 of the observation unit 7 is deviated, the deviation of the optical axis can be appropriately measured.

[0072] Also, by measuring the optical axis deviation using a plurality of diffracted lights, the measurement accuracy can be improved compared to the case of measuring the optical axis deviation using one diffracted light. (Effect)

[0073] <2. Modification Example> As described above, the embodiments have been described, but the present invention is not limited to the above-described configurations, and various modifications are possible.

[0074] In the above embodiment, it is not essential to make the 0th-order diffracted light and the ±1st-order diffracted lights enter the imaging device 71 of the observation unit 7. For example, only the 0th-order diffracted light may be made to enter the imaging device 71. However, by also making the ±1st-order diffracted lights enter the imaging device 71, for example, the contour 511b of the aperture 511a can be accurately extracted from the observation image.

[0075] Although the present invention has been described in detail, the above description is illustrative in all aspects and the present invention is not limited thereto. It is understood that numerous variations not illustrated can be envisioned without departing from the scope of the present invention. Each configuration described in each of the above embodiments and each variation can be appropriately combined or omitted as long as they do not conflict with each other.

Description of Reference Numerals

[0076] 2: Stage 2S: Upper surface (support surface) 3: Stage moving mechanism 9: Control unit 53: Light irradiation unit 61S: Fixed reflecting surface 63S: Fixed reflecting surface 65S: Movable reflecting surface 71: Image sensor 97: Optical axis measurement unit 98: Determination unit 99: Display 100: Exposure apparatus 510: Spatial light modulator 511: Projection optical system 511a: Diaphragm 511b: Contour 513: Mirror 515: Angle adjustment unit 533: Laser light source (light source) 535: Illumination optical system ES: Exposure surface OS: Observation surface W: Substrate

Claims

1. An exposure apparatus, comprising a stage for supporting an object, a stage moving mechanism for moving the stage in a predetermined moving direction, a light source for emitting laser light, a spatial modulator for spatially modulating the laser light from the light source, an illumination optical system for imaging the laser light from the light source onto the spatial modulator, a projection optical system for imaging the laser light modulated by the spatial modulator onto the exposure surface of the object, a light sensor for detecting the laser light emitted from the projection optical system on an observation surface located farther from the exposure surface than the projection optical system, an optical axis measurement unit for measuring the deviation amount of the optical axis of the laser light based on the position of the laser light detected by the light sensor, and an exposure apparatus comprising the same.

2. The exposure apparatus according to claim 1, further comprising an optical axis measurement unit that acquires the position of the laser light using the light amount distribution detected by the light sensor.

3. The exposure apparatus according to claim 1 or claim 2, further comprising a determination unit for determining whether or not the deviation amount measured by the optical axis measurement unit exceeds a threshold value.

4. The exposure apparatus according to claim 1 or claim 2, further comprising a mirror for reflecting the laser light from the illumination optical system and incidenting it on the spatial modulator, and an angle adjustment unit for adjusting the angle of the mirror. and an exposure apparatus comprising the same.

5. The exposure apparatus according to claim 1 or claim 2, wherein the spatial light modulator has a diffractive modulation element.

6. The exposure apparatus according to claim 4, wherein the diffractive modulation element has a plurality of reflecting surfaces arranged in a predetermined array direction, each of the reflecting surfaces has a fixed reflecting surface and a movable reflecting surface that can move up and down with respect to the fixed reflecting surface, the exposure apparatus.

7. The exposure apparatus according to claim 5, wherein the optical sensor can detect the zero-order diffracted light and the ± first-order diffracted light emitted from the diffractive modulation element, the deviation amount calculation unit calculates the deviation amount using the position of any one of the zero-order diffracted light and the ± first-order diffracted light detected by the optical sensor, the exposure apparatus.

8. The exposure apparatus according to claim 7, wherein the projection optical system has a diaphragm, the optical axis measurement unit identifies the contour of the diaphragm based on the shapes of the zero-order diffracted light and the ± first-order diffracted light detected by the optical sensor, and calculates the deviation amount using the position of any one of the zero-order diffracted light and the ± first-order diffracted light with respect to the contour, the exposure apparatus.

9. The exposure apparatus according to claim 1 or claim 2, wherein the stage has a support surface for supporting the object, the optical sensor is disposed inside the outer edge of the support surface, the exposure apparatus.

Images