Projection exposure device

Abstract

The present invention measures a change in the performance of a projection lens with high accuracy without affecting a tact time. This projection exposure device comprises: a conveyance control unit that controls conveyance of a substrate stage and an aberration and position deviation measurement stage so that the aberration and position deviation measurement stage is positioned at a projection exposure position while the substrate stage is positioned at a substrate replacement position; and an image capturing control unit that controls image capturing of an alignment mark image capturing unit and an aberration detection mark image capturing unit so that an image of a position deviation detection mark is captured by the alignment mark image capturing unit and images of a mask-side aberration detection mark and a reference mask-side aberration detection mark are captured by the aberration detection mark image capturing unit while the aberration and position deviation measurement stage is positioned at the projection exposure position by the conveyance control unit.

Description

Projection exposure equipment

[0001] The present invention relates to a projection exposure apparatus.

[0002] Patent Document 1 (JP 9-50959 A) describes an embodiment of a projection exposure apparatus that includes a substrate mark detection optical system that detects a substrate mark by illuminating a substrate mark with first detection light of a broadband wavelength without passing through a projection optical system and receiving the first detection light from the substrate mark without passing through a projection optical system, a mask mark detection optical system that detects a mask mark by illuminating a mask mark with second detection light via the projection optical system and receiving light from the mask mark, and a correction unit that is arranged between the mask and the substrate to correct chromatic aberration (axial chromatic aberration, lateral chromatic aberration (distortion), etc.) of the projection optical system for the second detection light reflected by the substrate. That is, Patent Document 1 describes an embodiment in which aberrations of the projection optical system are detected and corrected by comparing a mark provided on the mask with a mark provided on the projection exposure position.

[0003] Patent Document 2 (JP 10-172907 A) describes an embodiment of a projection exposure apparatus that includes a first alignment system that irradiates a first reference mark arranged on the image plane side of the projection optical system with first alignment light having a different wavelength from the exposure illumination light and detects optical information generated from the first reference mark via the projection optical system, and a second alignment system that irradiates a mark on a mask and a second reference mark arranged on the image plane side of the projection optical system with second alignment light having approximately the same wavelength as the exposure illumination light, detects the two marks via the projection optical system, and detects an offset amount due to chromatic aberration. That is, Patent Document 2 describes an embodiment in which aberrations in the projection optical system are detected and corrected by comparing a mark provided on the mask with a mark provided on the projection exposure position side.

[0004] Patent document 3 (U.S. Patent Publication US7403264B2) describes an aspect of a lithographic projection apparatus comprising a projection system for projecting a patterned beam onto a target portion of a substrate to form an image, predicting changes in the aberration of the projection system over time for measured aberration values, determining an application-specific effect of the predicted changes in the aberration of the projection system on at least one image parameter for a selected pattern, generating control signals specific to the selected pattern according to the predicted changes in the aberration of the projection system and the application-specific effect on the at least one image parameter, and responding to the control signals to compensate for the application-specific effect of the predicted changes in the aberration of the projection system on the image.

[0005] Patent Document 4 (Japanese Patent Laid-Open Publication No. 11-168062) describes a projection exposure position that includes a substrate stage, a projection optical system, a first mark detection means that has a detection center at a first position outside the projection field of the projection optical system and spaced a fixed distance from the optical axis of the projection optical system and is capable of optically detecting a mark on a photosensitive substrate, and a second mark detection means that optically detects a specific mark that exists at a substantially fixed second position within the field of the projection optical system, and a first reference mark that is provided on a part of the substrate stage and can be detected by the first mark detection means, and a second reference mark that is detected by the second mark detection means via the projection optical system. and a reference mark plate on which a first reference mark and a second reference mark detectable by the first mark detection means are arranged in a fixed positional relationship corresponding to the distance between the first position and the second position, a first positioning means for positioning a substrate stage so that the second reference mark can be detected by the second mark detection means, a second positioning means for detecting both a specific mark on the mask and the second reference mark by the second mark detection means and positioning the mask stage so that the two marks are in a predetermined positional relationship, and a first mark detection means for detecting a positional deviation between the detection center and the first reference mark and storing the positional deviation as a baseline error.

[0006] Patent Document 5 (JP Patent Publication No. 10-12520) describes an embodiment in which a light beam emitted from a first mark on a mask and a light beam emitted from a second mark provided in a shot area on a substrate to which a mask pattern is transferred and passing through the mask at a position a predetermined distance in a first direction from the first mark are detected, the amount of misalignment between the first mark and the second mark in a second direction perpendicular to the first direction is measured, the rotation angle between the shot area and the mask is detected, the measured amount of misalignment is corrected by an offset amount corresponding to the measured rotation angle, and the mask and shot area are aligned in the second direction based on the corrected amount of misalignment between the first mark and the second mark.

[0007] Patent Document 6 (U.S. Publication US20110027542A1) describes an embodiment in which an alignment camera detects an alignment mark on a workpiece and an alignment mark on a mask, calculates the amount of misalignment between the mask and workpiece and the amount of distortion of the workpiece based on the amount of misalignment between the two alignment marks detected by the alignment camera, and adjusts the alignment between the workpiece and mask based on the calculated amount of misalignment.

[0008] Patent Document 7 (JP 9-260273 A) describes an exposure apparatus including: a first measurement unit that observes an alignment mark on a photosensitive substrate via a projection optical system and measures the deviation from its own reference mark; a stage that carries the photosensitive substrate and drives it in directions parallel and perpendicular to the optical axis of the projection optical system; a second measurement unit that measures the parallel and perpendicular drive positions of the stage; a third measurement unit that simultaneously measures, via a projection lens, a pattern on a mask, a pattern on the photosensitive substrate, and a calibration pattern provided on the first stage for use in calibrating the first measurement unit; a fourth measurement unit that has a mask reference mark and simultaneously measures, by superimposing the mark on the mask and the mask reference mark; and a mask drive unit that drives the mask in the X, Y, and θ directions. That is, Patent Document 7 describes an embodiment in which a reference pattern on the mask and a calibration mark are aligned using an on-axis alignment system to determine and correct mask coordinates and magnification errors of the projection lens.

[0009] JP-A-9-50959 JP-A-10-172907 US Pat.

[0010] The most important performance characteristics of a projection exposure tool (stepper) are the resolution and overlay (alignment) accuracy of the pattern it forms. Because it is a manufacturing tool, high productivity (short takt time) is also required. However, the lens (projection lens) that projects the mask pattern is sensitive to changes in air pressure and temperature during production, and its performance continuously changes due to changes in air pressure and temperature, as well as the light energy used during exposure. Because these changes significantly affect exposure performance, it is necessary to measure or predict these changes during production and make various corrections to maintain constant performance. Correction control requires technology to measure changes in the projection lens's performance (aberrations), and various methods have been developed to measure individual aberrations. However, conventional techniques for measuring these aberrations with high precision require stopping production operations during measurements, which significantly reduces productivity. The present invention aims to measure changes in the projection lens's performance with high precision without affecting takt time.

[0011] The first aspect is a projection exposure apparatus that projects a pattern of a mask onto a substrate that has been transported to a projection exposure position via a projection optical system, the mask having formed thereon mask-side aberration detection marks for detecting aberration or aberration fluctuation of the projection optical system, the mask having formed thereon an alignment mark imaging unit that images an alignment mark provided on the substrate, a substrate stage on which the substrate is mounted, a reference mask having formed thereon reference mask-side aberration detection marks for detecting aberration or aberration fluctuation of the projection optical system and having formed thereon positional deviation detection marks for measuring positional deviation relative to a reference position of the alignment mark imaging unit, and the mask-side aberration detection marks and the reference mask-side aberration detection marks are imaged from the opposite side of the projection optical system across the reference mask. a transfer control unit that controls transfer of the substrate stage and the aberration / positional deviation measurement stage so that the aberration / positional deviation measurement stage is positioned at the projection exposure position while the substrate stage is positioned at the substrate exchange position; and an imaging control unit that controls imaging of the alignment mark imaging unit and the aberration detection mark imaging unit so that the alignment mark imaging unit images the positional deviation detection mark and the mask-side aberration detection mark and the reference mask-side aberration detection mark are imaged by the aberration detection mark imaging unit while the aberration / positional deviation measurement stage is positioned at the projection exposure position by the transportation control unit.

[0012] A second aspect is the projection exposure apparatus of the first aspect, wherein the imaging control unit controls imaging every time the substrate mounted on the substrate stage is exchanged at the substrate exchange position.

[0013] A third aspect is a projection exposure apparatus according to the second aspect, in which, each time a substrate mounted on the substrate stage is replaced at the substrate replacement position, the positional deviation of the alignment mark imaging unit is corrected based on the results of the imaging by the imaging control unit, and the aberration or aberration fluctuation of the projection optical system is corrected.

[0014] According to the first, second and third aspects, it is possible to measure the change in performance of the projection lens with high accuracy without affecting the takt time.

[0015] FIG. 1 is a perspective view showing the overall configuration of a projection exposure apparatus according to an embodiment. FIG. 2A is a view showing a partial configuration of the projection exposure apparatus according to an embodiment. FIG. 2B is a view showing a partial configuration of the projection exposure apparatus according to an embodiment. FIG. 3A is a view showing an example of the configuration of a mask. FIG. 3B is a view showing an enlarged view of a mark on the mask. FIG. 3C is a view showing an enlarged view of a mark on the mask. FIG. 3D is a view showing an enlarged view of a mark on the mask. FIG. 4 is a view showing an example of the configuration of a projection optical system. FIG. 5 is a view of a substrate seen from above, showing the positional relationship with an alignment mark imaging unit. FIG. 6A is a view showing an example of the configuration of a reference mask. FIG. 6B is a view showing an enlarged view of a mark on the reference mask. FIG. 6C is a view showing an enlarged view of a mark on the reference mask. FIG. 6D is a view showing an enlarged view of a mark on the reference mask. FIG. 6E is a view showing the relationship between the marks on the mask in a captured image and the marks on the reference mask. FIG. 6F is a view showing the relationship between the marks on the mask in a captured image and the marks on the reference mask. FIG. 7 is a flowchart showing the processing procedure for controlling the projection exposure apparatus according to an embodiment. Figure 8A corresponds to Figure 2A and shows a partial configuration of the projection exposure apparatus of the embodiment. Figure 8B corresponds to Figure 2B and shows a partial configuration of the projection exposure apparatus of the embodiment.

[0016] Hereinafter, an embodiment of a projection exposure apparatus according to the present invention will be described with reference to the drawings.

[0017] FIG. 1 is a perspective view showing the overall configuration of a projection exposure apparatus 200 according to an embodiment.

[0018] 2A and 2B are diagrams showing a partial configuration of a projection exposure apparatus 200 according to an embodiment.

[0019] 2A and 2B are views taken along the arrow A in FIG.

[0020] As shown in FIG. 1, the projection exposure apparatus 200 includes a lamp house 210, a mask blind projection optical system 220, a mask stage 230, a projection optical system 20, a substrate stage 50, an aberration / positional deviation measurement stage 80, a substrate transport unit 250, a substrate exchange unit 260, a mask library 270, a mask transport articulated robot 280, and a suspension 290.

[0021] The lamp house 210 is a housing in which an exposure light source 211, such as a mercury lamp, that emits illumination light IL for exposure is disposed. The mercury lamp that is used emits, for example, a mercury spectral line with a wavelength of 365 nm.

[0022] The mask blind projection optical system 220 projects a blind 221 that limits the exposure area onto the mask 10 via a dedicated optical system 220 .

[0023] The mask 10 is placed and held on the mask stage 230 .

[0024] The projection optical system 20 forms an image of the pattern drawn in the irradiation area AR1 of the mask 10 onto the projection exposure area AR2 of the substrate 30 transported to the projection exposure position P1.

[0025] The substrate 30 is placed and held on the substrate stage 50 .

[0026] The aberration and positional deviation measuring stage 80 is a stage for measuring the aberration or aberration fluctuation of the projection optical system 20 and the positional deviation of the alignment mark imaging unit 40, and the reference mask 60 is placed and held on it.

[0027] The substrate transport unit 250 transports the substrate stage 50 to the substrate exchange position P2 and the projection exposure position P1 in the X direction, and also transports the aberration / positional deviation measuring stage 80 to the projection exposure position P1 and the retract position P3 in the X direction.

[0028] The substrate exchange section 260 exchanges the substrate 30 on the substrate stage 50 positioned at the substrate exchange position P2.

[0029] The mask library 270 is a storage shelf for storing a plurality of replacement masks 30 while preventing foreign matter from adhering to the surface of the masks 10, and stores the plurality of masks 10 arranged at intervals.

[0030] The mask transport articulated robot 280 is a robot that handles the mask 10 on the mask stage 230 to replace it in response to a request to change the projection exposure pattern image formed on the substrate 30. The mask transport articulated robot 280 removes the mask 10 from the mask stage 230 and retrieves a new mask 10 from the mask library 270 and loads it onto the mask stage 230 by controlling the drive of each axis of the robot and controlling the gripping and releasing of a hand 281 at the tip of the arm.

[0031] The suspension 290 is provided between the floor of the clean room and the platform 170 on which the projection optical system 20, substrate stage 50, and mask stage 230 are mounted. The suspension 290 maintains the positional relationship between the projection optical system 20, substrate 30, and mask 10 with high precision, and prevents or suppresses vibrations from being transmitted to the projection optical system 20, substrate stage 50, and mask stage 230.

[0032] As shown in FIG. 2B, the projection exposure apparatus 200 projects the pattern of the mask 10 onto the substrate 30 transported to the projection exposure position P1 via the projection optical system 20.

[0033] 2A and 2B, the projection exposure apparatus 200 includes a mask 10, a projection optical system 20, a substrate 30, an alignment mark image capturing unit 40, a substrate stage 50, a reference mask 60, an aberration detection mark image capturing unit 70, an aberration and positional deviation measuring stage 80, a transport control unit 90, an image capturing control unit 100, an aberration and positional deviation measuring unit 110, and an aberration and positional deviation correcting unit 120. The transport control unit 90, the image capturing control unit 100, the aberration and positional deviation measuring unit 110, and the aberration and positional deviation correcting unit 120 constitute a controller 190 of the projection exposure apparatus 200.

[0034] (mask)

[0035] Fig. 3A shows an example of the configuration of the mask 10. Fig. 3A is a view of the mask 10 as seen from above.

[0036] The mask 10 is an original plate for an exposure image, in which a projection pattern PT1 serving as a circuit pattern is drawn in an irradiation area AR1 on, for example, a glass substrate. In addition to the projection pattern PT1, mask-side aberration detection marks M11, M12, M13, and M14 are formed on the mask 10. The mask-side aberration detection marks M11, M12, M13, and M14 are marks for detecting the aberration R or aberration variation ΔR of the projection optical system 20. The mask-side aberration detection marks M11, M12, M13, and M14 are formed in locations outside the irradiation area AR1.

[0037] As shown enlarged in Figure 3B, the mask-side aberration detection marks M11 and M12 are each marks for detecting positional misalignment of the mask 10, and the parts that do not transmit the illumination light IL are drawn as, for example, circular or elliptical shapes filled in black.

[0038] As shown enlarged in Figure 3C, the mask-side aberration detection marks M13 and M14 are each marks for focus detection, and are drawn, for example, as a row of multiple lines with a width of 5 μm for the black lines (portions that do not transmit the illumination light IL) and a spacing between each line (portions that transmit the illumination light IL).

[0039] The mask-side aberration detection marks M11 and M12 may have any shape or pattern as long as they are capable of detecting misalignment of the mask 10. For example, as shown in Fig. 3D, the mask-side aberration detection marks M11 and M12 may be cross-shaped.

[0040] (Projection optical system)

[0041] Fig. 4 shows an example of the configuration of the projection optical system 20. Fig. 5 is a view of the substrate 30 from above, showing each projection area. The following description will be made with reference to Figs. 3A, 4 and 5.

[0042] 4, the projection optical system 20 is a reduction or enlargement lens optical system composed of a group of multiple projection lenses, such as plano-convex, biconvex, plano-concave, or biconcave lenses, etc. The projection optical system 20 optically reduces or enlarges the image of the projection pattern PT1 in the irradiation area AR1 of the mask 10, and projects and exposes it as a projection exposure pattern PT2 onto a predetermined projection area AR2 on the substrate 30.

[0043] The image of the irradiation area AR1 of the mask 10 shown in Fig. 3A is projected onto the projection area AR2 on the substrate 30 shown in Fig. 5. Here, as shown by the arrows in Fig. 5, the exposure position is controlled so that the projection exposure pattern PT2 is sequentially exposed onto each projection area AR2 on the substrate 30. For example, the exposure position is controlled by driving the substrate stage 50 in the X and Y directions.

[0044] (substrate)

[0045] Any substrate 30 can be used as long as it can project a projection exposure pattern. In this embodiment, an FC-BGA (Flip Chip-Ball Grid Array) substrate is assumed, for example. Projection exposure of an FC-BGA substrate requires many repeated build-up steps, which takes time, and the wiring patterns on each layer are fine and dense. For this reason, the projection exposure apparatus 200 is required to have a short cycle time, high-precision alignment accuracy, and high resolution with aberrations minimized to the utmost, and the projection exposure apparatus 200 of this embodiment is suitable for these requirements.

[0046] As shown in Fig. 5, alignment marks M31 are formed on the substrate 30. Fig. 5 shows the positional relationship between the alignment mark imaging unit 40 (described later) and the alignment marks M31. Five alignment marks M31 are arranged along the Y-axis direction, which is the arrangement direction of the alignment mark imaging unit 40, and four alignment marks M31 are arranged along the X-axis direction. The alignment marks M31 are arranged, for example, at the four corners of each of eight rectangular projection areas AR2.

[0047] (Alignment mark imaging unit)

[0048] The alignment mark imaging unit 40 captures an image of the alignment mark M31 provided on the substrate 30.

[0049] The alignment mark imaging unit 40 is configured, for example, by a microscope camera having a digital camera attached to a microscope. As shown in Fig. 5, five alignment mark imaging units 40 are arranged along the Y-axis direction so that they can image each of the five alignment marks M31 arranged along the Y-axis direction on the substrate 30 from above.

[0050] As shown in FIG. 2B, a captured image signal S1 indicating an image captured by the alignment mark image capturing unit 40 is transmitted to the image capturing control unit 100 wirelessly or via a wired connection.

[0051] (Substrate stage)

[0052] As shown in FIG. 2A, the substrate stage 50 is driven by the substrate transport unit 250 in the three-dimensional directions of X, Y, and Z while placing and holding the substrate 30 thereon, and is also driven in tilt directions around the X-axis and Y-axis and in a rotation direction around the Z-axis.

[0053] The substrate 30 on the substrate stage 50 is exchanged at a substrate exchange position P2 by a substrate exchange unit 260. For example, the substrate exchange unit 260 is configured to include a substrate transport arm 262 equipped with a suction pad 261. The substrate 30 is gripped by the suction pad 261, and the substrate transport arm 262 is driven and controlled to load and unload the substrate 30.

[0054] In the projection exposure apparatus 200 of this embodiment, the projection exposure pattern PT2 is sequentially exposed onto each projection area AR2 of the substrate 30 by a step-and-repeat method in which the substrate stage 50 is driven in the X and Y directions as shown by the arrows in FIG.

[0055] (reference mask)

[0056] As shown in FIG. 2A, the reference mask 60 is placed and mounted on an aberration and positional deviation measuring stage 80 .

[0057] Fig. 6A shows an example of the configuration of the reference mask 60. Fig. 6A is a view of the reference mask 60 as seen from above.

[0058] The reference mask 60 is made of, for example, a glass substrate, on which reference mask side aberration detection marks M61 and M62 and a positional deviation detection mark M63 are formed.

[0059] The reference mask-side aberration detection marks M61 and M62 are marks corresponding to the mask-side aberration detection marks M11 and M12, respectively, and are marks for detecting the aberration R or aberration fluctuation ΔR of the projection optical system 20.

[0060] The positional deviation detection mark M63 is a mark for measuring the positional deviation ΔQ of the alignment mark imaging unit 40 relative to the reference position Q0.

[0061] As shown enlarged in Fig. 6B, the reference mask-side aberration detection marks M61 and M62 are marks for detecting the relative positions of the reference mask-side aberration detection marks M61 and M62 with respect to the mask-side aberration detection marks M11 and M12 as a positional deviation of the mask 10, and for example, the portions that do not transmit the illumination light IL are drawn in the shape of an elliptical or circular frame. The reference mask-side aberration detection marks M61 and M62 may have any shape or pattern as long as they are capable of detecting a positional deviation of the mask 10. For example, as shown in Fig. 6C, the reference mask-side aberration detection marks M61 and M62 may have portions that do not transmit the illumination light IL formed in the shape of a square frame.

[0062] 6A, the misalignment detection mark M63 is drawn, for example, in a grid pattern along the arrangement direction (Y-axis direction) of the alignment mark imaging unit 40. The misalignment detection mark M63 may have any shape or pattern as long as it can measure the misalignment ΔQ of the alignment mark imaging unit 40. For example, the misalignment detection mark M63 may be drawn in the form of a scale along the arrangement direction (Y-axis direction) of the alignment mark imaging unit 40, as shown in FIG. 6D.

[0063] (Aberration detection mark imaging unit)

[0064] As shown in FIG. 2A, the aberration detection mark imaging unit 70 is mounted on an aberration and positional deviation measuring stage 80 .

[0065] 2A, the aberration detection mark imaging unit 70 is disposed below the reference mask 60. The aberration detection mark imaging unit 70 images the mask-side aberration detection marks M11, M12, M13, and M14 and the reference mask-side aberration detection marks M61 and M62 from the opposite side of the projection optical system 20 across the reference mask 60. The aberration detection mark imaging unit 70 is configured, for example, by a digital camera. The aberration detection mark imaging unit 70 includes an aberration detection mark imaging unit 70A located on the substrate exchange position P2 side, an aberration detection mark imaging unit 70B located on the retracted position P3 side, and an aberration detection mark imaging unit 70B located between them on the optical axis 20C.

[0066] A captured image signal S2 indicating the image captured by the aberration detection mark capturing unit 70 is transmitted to the imaging control unit 100 wirelessly or via a wire.

[0067] (Aberration and positional deviation measurement stage)

[0068] As shown in FIG. 2A, the aberration / positional deviation measurement stage 80 places and holds the reference mask 60 on its upper surface, and also has the aberration detection mark imaging unit 70 mounted below the reference mask 60, while being driven in the three-dimensional directions of X, Y, and Z by the substrate transport unit 250.

[0069] The substrate transport unit 250 , the substrate stage 50 , the aberration and positional deviation measuring stage 80 , the projection optical system 20 , and the mask 10 are supported by a suspension 290 via a base 170 .

[0070] (Transport control unit)

[0071] 2A and 2B, the transport control unit 90 drives the substrate transport unit 250 to control the positions of the substrate stage 50 and the aberration / positional deviation measurement stage 80 in the three-dimensional directions of X, Y, and Z. The transport control unit 90 also controls the orientation of the substrate stage 50 in the tilt directions about the X and Y axes and the rotation direction about the Z axis (hereinafter referred to as position and orientation control).

[0072] As shown in FIG. 2A, the transport control unit 90 controls the transport of the substrate stage 50 and the aberration / positional deviation measurement stage 80 by the substrate transport unit 250 so that the aberration / positional deviation measurement stage 80 is positioned at the projection exposure position P1 while the substrate stage 50 is positioned at the substrate exchange position P2.

[0073] As shown in FIG. 2B, the transport control unit 90 controls the transport of the substrate stage 50 and the aberration / positional deviation measurement stage 80 by the substrate transport unit 250 so that the aberration / positional deviation measurement stage 80 is positioned at the retracted position P3 while the substrate stage 50 is positioned at the projection exposure position P1.

[0074] In this embodiment, the substrate stage 50 and the aberration and positional deviation measuring stage 80 are controlled in transportation so that they are positioned in synchronization with adjacent positions (P2, P1) or (P1, P3).

[0075] (Imaging control unit)

[0076] The imaging control unit 100 controls the imaging of the alignment mark imaging unit 40 and the aberration detection mark imaging unit 70 so that, while the aberration / positional deviation measurement stage 80 is positioned at the projection exposure position P1 by the transport control unit 90, the alignment mark imaging unit 40 images the positional deviation detection mark M63, and the aberration detection mark imaging unit 70 images the mask side aberration detection marks M11, M12, M13, and M14 and the reference mask side aberration detection marks M61 and M62.

[0077] (Aberration and positional deviation measurement unit)

[0078] The aberration / positional deviation measurement unit 110 measures the positional deviation ΔQ of the alignment mark imaging unit 40 based on the imaging results by the imaging control unit 100 at the substrate exchange position P2, and also measures the aberration R or aberration variation ΔR of the projection optical system 20 each time the substrate 30 mounted on the substrate stage 50 is exchanged.

[0079] (Aberration and positional deviation correction unit)

[0080] The aberration / positional deviation correction unit 120 corrects the positional deviation ΔQ of the alignment mark imaging unit 40 in accordance with the measured value of the positional deviation ΔQ of the alignment mark imaging unit 40 each time the substrate 30 mounted on the substrate stage 50 is exchanged at the substrate exchange position P2, and also corrects the aberration R or aberration variation ΔR of the projection optical system 20 in accordance with the measured value of the aberration R or aberration variation ΔR of the projection optical system 20.

[0081] (Control processing procedure)

[0082] FIG. 7 is a flowchart showing the control processing procedure of the projection exposure apparatus 200 according to the embodiment.

[0083] (Mask replacement and setting process S11)

[0084] As shown in FIG. 1, the mask 10 is carried out from the mask stage 230 by the mask carrying articulated robot 270 , and a new mask 10 is taken out from the mask library 270 and set on the mask stage 230 .

[0085] (Substrate replacement process and aberration / positional deviation correction process S12)

[0086] As shown in FIG. 2A, the substrate stage 50 is positioned at the substrate exchange position P2, and the aberration and positional deviation measuring stage 80 is positioned at the projection exposure position P1.

[0087] The substrate 30 on the substrate stage 50 is exchanged at a substrate exchange position P2 by the substrate exchange unit 260. The substrate 30 is carried in and out via, for example, a roller conveyor (not shown).

[0088] The imaging control unit 100 controls imaging by the alignment mark imaging unit 40 by sending an imaging command signal to the alignment mark imaging unit 40. A captured image signal S1 indicating an image captured by the alignment mark imaging unit 40 is input to the imaging control unit 100.

[0089] The aberration and positional deviation measuring unit 110 measures the positional deviation ΔQ of the alignment mark imaging unit 40 based on the captured image signal S1. That is, the aberration and positional deviation measuring unit 110 measures the fluctuation in the relative position of the alignment mark imaging unit 40 with respect to the projected image.

[0090] When the alignment mark imaging unit 40 is positioned at the reference position Q0, the misalignment detection mark M63 is imaged at a predetermined reference position in the captured image. However, when the alignment mark imaging unit 40 is positioned away from the reference position Q0, the misalignment detection mark M63 is imaged at a position in the captured image that is shifted from the predetermined reference position. The aberration / misalignment measuring unit 110 measures the misalignment ΔQ of the alignment mark imaging unit 40, for example, by measuring the amount of deviation of the misalignment detection mark M63 from the reference position in the captured image using image processing.

[0091] The aberration and positional deviation correction unit 120 corrects the positional deviation ΔQ of the alignment mark imaging unit 40 in accordance with the measurement value of the positional deviation ΔQ of the alignment mark imaging unit 40. If a mechanism capable of adjusting the position and attitude of the alignment mark imaging unit 40 is provided, the positional deviation ΔQ of the alignment mark imaging unit 40 can be corrected by adjusting the position and attitude of the alignment mark imaging unit 40. If a mechanism capable of adjusting the position and attitude of the alignment mark imaging unit 40 is not provided, the positional deviation ΔQ of the alignment mark imaging unit 40 can be corrected by moving the substrate stage 50 in alignment processing S13, which will be described later, taking into account the measurement value of the positional deviation ΔQ of the alignment mark imaging unit 40.

[0092] The imaging control unit 100 controls imaging by the aberration detection mark imaging unit 70 by transmitting an imaging command signal to the aberration detection mark imaging unit 70. A captured image signal S2 indicating an image captured by the aberration detection mark imaging unit 70 is input to the imaging control unit 100.

[0093] The aberration and positional deviation measuring unit 110 measures the aberration R or aberration fluctuation ΔR of the projection optical system 20 based on the captured image signal S2. That is, the aberration and positional deviation measuring unit 110 measures changes in focus in the direction of the optical axis 20C of the projection optical system 20, changes in the image plane, and changes in magnification and distortion due to changes in thermal expansion of the mask 10. Various aberrations R can be measured as follows.

[0094] (Mask 10 Positional Misalignment) When the aberration R of the projection optical system 20 is below a reference level, the relative positional shift between the mask-side aberration detection marks M11, M12 and the reference mask-side aberration detection marks M61, M62 in the captured image is within a predetermined threshold. However, as shown in FIG. 6E , when the aberration R of the projection optical system 20 exceeds the reference level, the relative positional shift between the mask-side aberration detection marks M11, M12 and the reference mask-side aberration detection marks M61, M62 in the captured image exceeds the predetermined threshold. The aberration / positional shift measurement unit 110 moves the position of the mask 10 to measure the relative positional shift between the center positions of the mask-side aberration detection marks M11, M12 and the reference mask-side aberration detection marks M61, M62 in the captured image by the aberration detection mark imaging units 70A, 70B, from a position where they are shifted to a position where they coincide. The measured relative positional shift is defined as the aberration R of the projection optical system 20 (mask 10 positional shift).

[0095] (Focus Change and Field Curvature of the Projection Lens) When the aberration R of the projection optical system 20 is below a reference level, the deviation of the image plane of the mask-side aberration detection marks M13 and M14 from the best focus position is within a predetermined threshold. However, when the aberration R of the projection optical system 20 exceeds the reference level, the deviation of the image plane of the mask-side aberration detection marks M13 and M14 from the best focus position exceeds the predetermined threshold. The aberration / positional deviation measurement unit 110 moves the aberration detection mark imaging unit 70C up and down to measure the vertical movement amount until the aberration detection mark imaging unit 70C reaches a height position (best focus position) where the contrast of the striped pattern of the mask-side aberration detection marks M13 and M14 in the captured image is at its best. The measured vertical change amount of the aberration detection mark imaging unit 70C is taken as the aberration R of the projection optical system 20 (focus change and field curvature of the projection lens).

[0096] (Magnification Change of Projection Lens) When the aberration R of the projection optical system 20 is below a reference level, the dimensional difference between the mask-side aberration detection marks M11, M12 and the reference mask-side aberration detection marks M61, M62 in the captured image is below a predetermined threshold. However, as shown in FIG. 6F , when the aberration R of the projection optical system 20 exceeds the reference level, the dimensional difference between the mask-side aberration detection marks M11, M12 and the reference mask-side aberration detection marks M61, M62 in the captured image exceeds the predetermined threshold. The aberration / positional deviation measurement unit 110 measures the dimensional difference between the mask-side aberration detection marks M11, M12 and the reference mask-side aberration detection marks M61, M62 in the captured image through image processing. The measured dimensional difference is taken as the aberration R of the projection optical system 20 (magnification change of the projection lens).

[0097] The aberration and positional deviation correction unit 120 corrects the aberration R of the projection optical system 20 in accordance with the measurement value of the aberration R of the projection optical system 20. For example, by driving some of the projection lenses 21 and 22 in the projection optical system 20 in the Z-axis direction, which is the direction of the optical axis 20C, the focal position and projection magnification of the projection optical system 20 can be adjusted to correct the aberration R. Also, for example, by driving the mask stage 230 in the X and Y directions, the X and Y positions of the mask 10 can be adjusted to correct the aberration R.

[0098] Instead of correcting the aberration R, the aberration variation ΔR of the current aberration relative to the previous aberration may be corrected. As a result, the aberration R or the aberration variation ΔR of the projection optical system 20 can be suppressed (alignment process S13).

[0099] Next, as shown in FIG. 2B, the substrate stage 50 is transported to the projection exposure position P1 by the transport control unit 90, and the aberration and positional deviation measuring stage 80 is transported to the retracted position P3.

[0100] When the substrate stage 50 is positioned at the projection exposure position P1, the imaging control unit 100 controls imaging by the alignment mark imaging unit 40 by sending an imaging command signal to the alignment mark imaging unit 40. An imaging image signal S1 indicating the image captured by the alignment mark imaging unit 40 is input to the imaging control unit 100. When the substrate 30 passes under the alignment mark imaging unit 40, the alignment mark imaging unit 40 captures an image of the coordinate position of each alignment mark M31.

[0101] The aberration and positional deviation measuring unit 110 calculates the positional deviation of the alignment marks M31 in the captured image from a reference position and the tilt angle of each reference alignment mark M31 from the arrangement direction, and measures the coordinate position, tilt, and magnification of the substrate 30. The position and attitude of the substrate stage 50 are controlled according to the measured coordinate position, tilt, and magnification of the substrate 30.

[0102] Here, the position and attitude of the substrate stage 50 are controlled taking into consideration the measurement value of the positional deviation ΔQ of the alignment mark imaging unit 40 measured in the substrate exchange process and the aberration / positional deviation correction process S12. As a result, the positional deviation ΔQ of the alignment mark imaging unit 40 can be corrected.

[0103] As a result, the deterioration of the alignment accuracy of the substrate 30 due to the positional deviation ΔQ of the alignment mark imaging unit 40 can be suppressed, and the alignment accuracy can be maintained at a high level of accuracy.

[0104] (Exposure control process S14)

[0105] Next, the transport control unit 90 controls the position and attitude of the substrate stage 50 so that the projection exposure pattern PT2 is projected and exposed sequentially onto each projection area AR2 on the substrate 30 based on the coordinate position, inclination, and magnification of the substrate 30 measured in the alignment process S13.

[0106] As a result, the projection exposure pattern PT2 is sequentially exposed onto each projection area AR2 on the substrate 30 as shown in FIG.

[0107] (Substrate unloading process S15)

[0108] Next, as shown in FIG. 2A, the substrate stage 50 is transported to the substrate exchange position P2 by the transport control unit 90, and the aberration and positional deviation measuring stage 80 is transported to the projection exposure position P1.

[0109] Thereafter, if there is no need to replace the mask 10 (determination N in S16), the procedure proceeds to the substrate replacement process and aberration / positional deviation correction process S12. If there is a need to replace the mask 10 (determination Y in S16), the procedure returns to the mask replacement and setting process S11.

[0110] In the above-described embodiment, the substrate stage 50 and the aberration / positional deviation measuring stage 80 are separate entities, but the substrate stage 50 and the aberration / positional deviation measuring stage 80 may also be integrated.

[0111] 8A and 8B correspond to FIGS. 2A and 2B, respectively, and show an example of the configuration of a projection exposure apparatus 200 in which the substrate stage 50 and the aberration / positional deviation measurement stage 80 are configured as an integrated stage 86 via a connecting member 85.

[0112] As shown in FIG. 8A, the transport control unit 90 controls the transport of the stage 86 by the substrate transport unit 250 so that the substrate 30 is positioned at the substrate exchange position P2 and the reference mask 60 is positioned at the projection exposure position P1.

[0113] As shown in FIG. 8B, the transport control unit 90 controls the transport of the stage 86 by the substrate transport unit 250 so that the substrate 30 is positioned at the projection exposure position P1 and the reference mask 60 is positioned at the retracted position P3.

[0114] As described above, according to the embodiment, while the substrate 30 is being replaced, the aberration R or aberration variation ΔR of the projection optical system 20 is measured, and the positional deviation ΔQ of the alignment mark imaging unit 40 is measured. Therefore, it is possible to suppress the aberration R or aberration variation ΔR of the projection optical system 20 without affecting the takt time of the substrate exposure, and it is possible to suppress a decrease in the alignment accuracy of the substrate 30 and maintain high accuracy of the alignment accuracy. Therefore, according to the embodiment, it is possible to provide to the market a projection exposure apparatus 200 that is suitable for exposing substrates, such as high-density package substrates, which require a shorter substrate exposure cycle time and high resolution in the exposure pattern image.

[0115] REFERENCE SIGNS LIST 10 mask 20 projection optical system 30 substrate 40 alignment mark imaging unit 50 substrate stage 60 reference mask 70 aberration detection mark imaging unit 80 aberration and positional deviation measurement stage 90 transport control unit 100 imaging control unit 200 projection exposure apparatus

Claims

1. A projection exposure apparatus that projects a mask pattern onto a substrate conveyed to a projection exposure position through a projection optical system, wherein a mask-side aberration detection mark for detecting an aberration or aberration variation of the projection optical system is formed on the mask, an alignment mark imaging unit that images an alignment mark provided on the substrate, a substrate stage on which the substrate is mounted, a reference mask on which a reference mask-side aberration detection mark for detecting an aberration or aberration variation of the projection optical system is formed and a displacement detection mark for measuring a displacement with respect to a reference position of the alignment mark imaging unit is formed, and an aberration / displacement measurement stage on which an aberration detection mark imaging unit that images the mask-side aberration detection mark and the reference mask-side aberration detection mark from the opposite side of the projection optical system across the reference mask is mounted, a transfer control unit that controls the transfer of the substrate stage and the aberration / displacement measurement stage so that the aberration / displacement measurement stage is positioned at the projection exposure position while the substrate stage is positioned at a substrate exchange position, and an imaging control unit that controls the imaging of the alignment mark imaging unit and the aberration detection mark imaging unit so that the displacement detection mark is imaged by the alignment mark imaging unit and the mask-side aberration detection mark and the reference mask-side aberration detection mark are imaged by the aberration detection mark imaging unit while the aberration / displacement measurement stage is positioned at the projection exposure position by the transfer control unit.

2. The projection exposure apparatus according to claim 1, wherein imaging control by the imaging control unit is executed each time a substrate mounted on the substrate stage is exchanged at the substrate exchange position.

3. The projection exposure apparatus according to claim 2, wherein each time a substrate mounted on the substrate stage is exchanged at the substrate exchange position, the displacement of the alignment mark imaging unit is corrected based on the result of the imaging by the imaging control unit, and the aberration or aberration variation of the projection optical system is corrected.

Images