JP7361599B2 - Exposure equipment and article manufacturing method - Google Patents

Description

The present invention relates to an exposure apparatus and an article manufacturing method.

Several methods are known for measuring imaging characteristics (eg, distortion, focal position, etc.) of a projection optical system of an exposure apparatus. Patent Document 1 describes a method for measuring distortion of a projection optical system of an exposure apparatus. The measurement method described in Patent Document 1 will be explained with reference to FIG. First, a first mark 101 and a second mark 102 are transferred in an overlapping manner by exposure to a substrate 100 coated with a photosensitive material, and the photosensitive material is developed. As a result, a mark corresponding to the first mark 101 and a mark corresponding to the second mark 102 are formed on the substrate 100. After that, the amount of deviation between the mark corresponding to the first mark 101 and the mark corresponding to the second mark 102 is measured using a microscope, and the simultaneous equations created from the measurement results are solved to obtain the distortion of the projection optical system. be able to. According to this method, distortion can be determined with high accuracy by removing the influence of stage drive errors.

Patent Document 2 describes a method of measuring imaging characteristics (distortion, focal position, etc.) of a projection optical system without exposing a wafer. The measurement method described in Patent Document 2 will be explained with reference to FIG. In the measurement method described in Patent Document 2, as shown in FIG. 9A, a reticle 112 having a slit-shaped first mark 113 is held by a reticle stage 110, and a pattern having a slit-shaped second mark 116 is formed. A plate 117 is placed on the wafer stage 111. Then, the exposure light 114 is applied to the first mark 113, and the exposure light 114 that has passed through the first mark 113 is applied to the second mark 116 via the projection optical system 115, and the exposure light 114 that has passed through the second mark 116 is applied to the second mark 116. is received by the photoelectric sensor 118. In this state, the wafer stage 111 is driven in the optical axis direction (Z direction) of the projection optical system 115 or in the direction perpendicular to the optical axis (X/Y direction). Thereby, as shown in FIG. 9(b), the relationship between the position of the wafer stage 111 and the output (light amount) of the photoelectric sensor 118 is obtained. For example, by receiving exposure light with the photoelectric sensor 118 while driving the wafer stage 111 in the optical axis direction, the position of the wafer stage 111 when the amount of light is maximum can be determined as the focal position. In addition, by receiving exposure light with the photoelectric sensor 118 while driving the wafer stage 111 in a direction perpendicular to the optical axis, the imaging position (X/Y position) of the first mark 113 in the direction perpendicular to the projection optical system can be determined. can be found. By performing such measurements on the plurality of first marks 113 on the mask, the imaging characteristics of the projection optical system can be determined without exposing and developing the wafer. Furthermore, as shown in FIG. 10, Patent Document 2 describes that a large number of second marks 123 and a large number of photoelectric sensors 121 are arranged on a pattern plate 120 to simultaneously measure imaging characteristics at a plurality of positions. has been done.

Japanese Patent Application Publication No. 2004-63905 Japanese Patent Application Publication No. 8-227847

However, in the method of Patent Document 1, it is necessary to prepare a substrate coated with a photosensitive material, perform exposure and development, and then perform measurement using a microscope. Therefore, the method of Patent Document 1 is not suitable for regular measurement because exposure and development take a considerable amount of time. Furthermore, equipment other than the exposure device is required to perform coating and development. In the method of Patent Document 2, when there is only one photoelectric sensor, the measurement results are affected by the drive error of the wafer stage. Further, arranging a large number of photoelectric sensors on the wafer stage increases the size of the wafer stage and increases cost.

The present invention provides an advantageous technique for measuring the imaging characteristics of a projection optical system at low cost and with high precision without performing exposure and development.

One aspect of the present invention provides an exposure apparatus that includes an illumination system that illuminates a mask placed on a surface to be illuminated, a projection optical system that projects an image of the mask onto a substrate, and a substrate stage that supports the substrate. Accordingly, the exposure apparatus includes a sensor mounted on the substrate stage and a control unit that controls the sensor, and the control unit includes at least two marks selected from a plurality of marks arranged on the illuminated surface. A detection process of detecting the image formation position of one mark using the sensor is performed multiple times, and a movement process of moving the substrate stage on which the sensor is mounted is performed between the detection processes. implement. The movement of the substrate stage in the movement process includes a portion of at least two marks selected from the plurality of marks in the detection process before the movement process and a part of the plurality of marks selected in the detection process after the movement process. At least two marks selected from the marks are carried out so that a portion thereof is common.

According to the present invention, an advantageous technique is provided for measuring the imaging characteristics of a projection optical system at low cost and with high precision without performing exposure and development.

FIG. 1 is a diagram showing the configuration of an exposure apparatus according to a first embodiment. A diagram illustrating marks. FIG. 3 is a diagram for explaining the measurement method of the first embodiment. FIG. 3 is a diagram illustrating the relationship between the output of a photoelectric conversion unit and the position of a substrate stage. FIG. 7 is a diagram for explaining another example according to the measurement method of the first embodiment. FIG. 7 is a diagram showing the configuration of an exposure apparatus according to a second embodiment. FIG. 7 is a diagram schematically showing the output of an image sensor of an exposure apparatus according to a second embodiment. A diagram for explaining a conventional exposure apparatus (Patent Document 1). A diagram for explaining a conventional exposure apparatus (Patent Document 2). Diagram for explaining a conventional exposure apparatus (Patent Document 2)

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the claimed invention. Although a plurality of features are described in the embodiments, not all of these features are essential to the invention, and the plurality of features may be arbitrarily combined. Furthermore, in the accompanying drawings, the same or similar components are designated by the same reference numerals, and redundant description will be omitted.

FIG. 1 shows the configuration of an exposure apparatus EX according to the first embodiment. Although the exposure apparatus EX of the first embodiment is configured as a scanning exposure apparatus, the exposure apparatus according to the present invention is not limited to a scanning exposure apparatus, and may also be applied to a stepper or the like. In the following, directions and postures will be explained using an XYZ coordinate system in which the Z axis is a direction parallel to the optical axis of the projection optical system of the exposure apparatus EX, and the XY plane is a plane perpendicular to the optical axis. The XY plane, the X direction, and the Y direction are also directions parallel to the image plane of the projection optical system.

The exposure apparatus EX can include an illumination system IL, a mask stage 203, a projection optical system 204, a substrate stage 206, and a control section 232. The illumination system IL illuminates a mask 202 placed on a surface to be illuminated (an object surface of the projection optical system 204) with illumination light (exposure light) 210. In the exposure apparatus EX configured as a scanning exposure apparatus, the illumination system IL illuminates a slit-shaped illuminated area whose dimension in the scanning direction (Y direction) is smaller than the dimension in the direction perpendicular to the scanning direction (X direction). In the first embodiment, the slit-shaped illuminated area is a rectangular area whose dimension in the Y direction is smaller than the dimension in the X direction, but it may be an area having another shape, such as an arc shape, for example. Illumination system IL can include, for example, a light source 200 and an illumination optical system 201 that illuminates mask 202 using light from light source 200.

Mask stage 203 holds mask 202. The position and orientation of the mask stage 203 are measured by a measuring instrument 230 such as a laser interferometer or a laser scale. The control unit 232 generates a control signal for controlling the mask stage drive mechanism 231 by PID calculation or the like based on the target command value and the measurement result by the measuring device 230. Mask stage drive mechanism 231 drives mask stage 203 according to this drive signal, and controls the position and orientation of mask stage 203. This drives the mask 202. Driving the mask 202 includes driving the mask 202 to scan in the scanning direction (Y direction) for scanning exposure. The position of the mask stage 203 may include positions in the X direction, Y direction, and Z direction. The posture of the mask stage 203 can include θ (rotation around the Z axis), pitch (rotation around the X axis), and roll (rotation around the Y axis).

The substrate stage 206 has a substrate chuck 207 that holds the substrate 205. Substrate chuck 207 may hold substrate 205 by, for example, vacuum suction. The position and orientation of the substrate stage 206 are measured by a measuring instrument 270 such as a laser interferometer or a laser scale. The control unit 232 generates a control signal for controlling the substrate stage drive mechanism 271 by PID calculation or the like based on the target command value and the measurement result by the measuring device 270. Substrate stage drive mechanism 271 drives substrate stage 206 according to this drive signal, and controls the position and attitude of substrate stage 206. This drives the substrate 205. Driving the substrate 205 includes driving the substrate 205 to scan in the scanning direction (Y direction) for scanning exposure. The position of substrate stage 206 may include positions in the X direction, Y direction, and Z direction. The posture of the substrate stage 206 can include θ (rotation around the Z axis), pitch (rotation around the X axis), and roll (rotation around the Y axis).

Projection optical system 204 projects an image of the illuminated area of mask 202 onto substrate 205 . In scanning exposure, the mask 202 is scanned in the scanning direction (Y direction) with respect to the illuminated area, and in synchronization with this, the substrate 205 is also scanned in the scanning direction (Y direction). Therefore, by scanning exposure, an image of the entire pattern area of the mask 202 is transferred to the photosensitive material of the substrate 205. The control unit 232 is, for example, a PLD (Programmable Logic Device) such as FPGA (Field Programmable Gate Array), or an ASIC (Application Specific Integrated). Abbreviation for Circuit), or a general-purpose computer with a built-in program or a dedicated computer, or a combination of all or part of these.

Next, a system for measuring the imaging characteristics of the projection optical system 204 will be described. The mask 202 may have a first mark group 220, as illustrated in FIG. 2(b). The first mark group 220 may include a plurality of first marks 250. The plurality of first marks 250 may have the same shape. The plurality of first marks 250 may be arranged at a predetermined arrangement pitch. As illustrated in FIG. 2A, each first mark 250 includes a slit mark (hereinafter referred to as an H mark) 251 whose dimension in the X direction is larger than the dimension in the Y direction, and a slit mark whose dimension in the Y direction is larger than the dimension in the X direction. (hereinafter referred to as V mark) 252. The H mark 251 is a sub-mark for measuring imaging characteristics (distortion) in the Y direction, and can also be understood as a sub-mark extending in the X direction. The V mark 252 is a sub-mark for measuring imaging characteristics in the X direction, and can also be understood as a sub-mark extending in the Y direction. The X direction can be understood as a first direction, and the Y direction can be understood as a second direction intersecting the first direction. In FIG. 2, the shaded area is a light shielding film that blocks light. The first mark group 220 can be arranged to cover or include the inspection area on the object plane of the projection optical system 204. The inspection area can be an illuminated area, in which case the plurality of first marks 250 are arranged in the illuminated area.

In the example of FIG. 2(b), the inspection area is a rectangular area with a dimension in the X direction of 750 [mm] and a dimension in the Y direction of 75 [mm], and the arrangement pitch of the first marks 250 is 25 [mm]. sell. The arrangement pitch in the X direction and the arrangement pitch in the Y direction may be different from each other, but in the example of FIG. 2(b), they are the same. In the example of FIG. 2B, the number of first marks 250 arranged in the Y direction is 4, the number of arranged marks in the X direction is 31, and 124 first marks 250 are arranged in total. Specifications such as the arrangement pitch and the number of first marks 250 can be arbitrarily determined. The first mark group 220 may be provided on the mask 202 for exposing the substrate 205, may be provided on a mask (measurement mask) different from the mask 202 for exposing the substrate 205, or may be provided on a mask 202 for exposing the substrate 205. It may be provided on the stage 203. The first mark group 220 can be manufactured, for example, by providing a patterned light-blocking material on a glass plate.

The exposure apparatus EX can further include a sensor SE mounted on the substrate stage 206. Sensor SE may be placed in a different area than substrate chuck 207. The sensor SE includes a plate 241 having a plurality of second marks (openings) 260 having a shape similar to each of the plurality of first marks 250, as illustrated in FIGS. 2(c) and 2(d). It can be included. Further, the sensor SE may include a plurality of photoelectric conversion units 242 that detect the light flux that has passed through the plurality of second marks (apertures) 260. The plurality of second marks 260 constitute a second mark group 240. The plate 241 can be arranged so that the height of its surface (position in the Z direction) matches the designed image plane of the projection optical system 204. As illustrated in FIG. 2(c), each second mark 260 includes a slit mark (hereinafter referred to as an H mark) 261 whose dimension in the X direction is larger than the dimension in the Y direction, and a slit mark whose dimension in the Y direction is larger than the dimension in the X direction. (hereinafter referred to as V mark) 262. The H mark 261 is a sub-mark for measuring imaging characteristics (distortion) in the Y direction, and can also be understood as a sub-mark extending in the X direction. The V mark 262 is a mark for measuring imaging characteristics in the X direction, and can be understood even if it extends in the Y direction.

In the example of FIG. 2D, the number of second marks 260 arranged in the Y direction is 2, the number of arranged marks 260 in the X direction is 2, and a total of 4 second marks 260 are arranged. The arrangement pitch of the second marks 260 is determined according to the arrangement pitch of the first marks 250 and the magnification of the projection optical system 204. In the first embodiment, the projection optical system 204 is a same-magnification optical system, and the arrangement pitch of the second marks 260 is the same as the arrangement pitch of the first marks 250, that is, 25 [mm]. The projection optical system 204 may be a reduction optical system or an enlargement optical system, and in that case, the arrangement pitch of the second marks 260 is determined according to the magnification of the projection optical system 204. In the first embodiment, the area occupied by the second mark group 240 is about 25 [mm] plus the peripheral light shielding part, as illustrated in FIG. 2(d). Therefore, the area occupied by the second mark group 240 is smaller than the area occupied by the first mark group 220 (as illustrated in FIG. 2(b), an area covering 750 [mm] x 75 [mm]). It's small.

A photoelectric conversion unit 242 is arranged under each second mark. Signals detected by each photoelectric conversion unit 242 are provided to the control unit 232. The control unit 232 can take in the signals provided from each photoelectric conversion unit 242 and the position information of the substrate stage 206 measured by the measuring device 270 in association with each other.

In the first embodiment, one photoelectric conversion unit 242 is provided for a set of an H mark 261 and a V mark 262. Therefore, measurements using the H mark 261 (and H mark 251) and measurements using the V mark 262 (and V mark 252) are performed at different timings. The arrangement of the H mark 251 and V mark 252 of the first mark 250 and the H mark 261 and V mark 262 of the mark 260 can satisfy the following conditions. This condition is that when the H mark 251 and the H mark 261 overlap, the V mark 252 and the V mark 262 do not overlap, and when the V mark 252 and the V mark 262 overlap, the H mark 251 and the H mark 261 do not overlap. They do not overlap. In other words, the condition is that when measuring using the H mark 251 and the H mark 261, the V mark 252 and the V mark 262 do not overlap, and the measurement is performed using the V mark 252 and the V mark 262. At this time, the H mark 251 and the H mark 261 do not overlap. FIG. 2E shows an example of a configuration in which the H mark 251 and the H mark 261 do not overlap when measuring using the V mark 252 and the V mark 262.

In the first embodiment, for ease of understanding, the projection optical system 204 uses a configuration in which the image is not inverted (the first mark 250 is projected onto the image plane of the projection optical system 204 without being inverted in the X direction and the Y direction). configuration) is explained. When the image is inverted by the projection optical system 204, the second mark 260 is inverted in accordance with the inversion of the image. For example, in the case of a projection optical system that inverts an image in the X direction, a second mark inverted in the X direction is provided. Further, in the first embodiment, a combination of H mark and V mark is illustrated, but in order to understand the characteristics of the projection optical system in detail, for example, a mark inclined at 45 degrees with respect to the scanning direction in scanning exposure and a 135 A tilted mark may be additionally provided. Even in this case, an arrangement may be adopted in which only one of the plurality of marks forming the first mark 250 and only one mark of the plurality of marks forming the second mark 260 overlap each other. Furthermore, in the first embodiment, one common photoelectric conversion unit is provided for the plurality of marks constituting the second mark 260; A photoelectric conversion section may be provided. In this case, the plurality of marks making up the second mark 260 can be measured simultaneously.

Next, a method for measuring the imaging characteristics (distortion) of the projection optical system 204 will be described. The control unit 232 uses the sensor SE to determine the imaging position of at least two first marks 250 selected from the plurality of first marks 250 of the mask 202 arranged on the illuminated surface (the object surface of the projection optical system 204). Detection processing is performed multiple times. Further, the control unit 232 performs a movement process to move the substrate stage 206 on which the sensor SE is mounted between the detection processes. Here, the movement of the substrate stage 206 in the movement process is defined as one of at least two marks 250 selected from a plurality of marks 250 in a detection process (for example, it can be understood as a first detection process) before the movement process. a portion of at least two marks 250 selected from the plurality of marks 250 in a detection process after the movement process (for example, it can be understood as a second detection process after the first detection process); are carried out in a common manner.

This will be explained with reference to FIG. For convenience of explanation, as shown in FIGS. 3A and 3B, numbers are assigned to the first mark 250 such as M11, M12, etc., and numbers such as P11 are assigned to the second mark 260. , P12, etc. First, the control unit 232 controls the position of the mask stage 203 so that the first mark group 220 of the mask 202 is placed in the inspection area of the projection optical system 204. The position of the mask stage 203 can be maintained until the measurement of the imaging characteristics of the projection optical system 204 is completed.

Next, the control unit 232 controls the substrate so that the positions of the second marks P11, P12, P21, and P22 almost match the imaging positions of the first marks M11, M12, M21, and M22, as shown in FIG. 3(c). Controls the stage drive mechanism 271. The drive target position of the substrate stage 206 at this time may be a position that is shifted by a distance corresponding to the distortion measurement range from the designed imaging position of the first marks M11, M12, M21, and M22. For example, if the distortion measurement range is ±10 [um], the control unit 232 positions the second mark at a position that is deviated from the designed imaging position by 10 [um].

Regarding the position of the substrate stage 206 in the Z direction, if the focal position of the projection optical system 204 is known in advance, the control unit 232 adjusts the position of the substrate stage 206 so that the second mark coincides with the focal position of the projection optical system 204. Control position. If the focal position of the projection optical system 204 is not known in advance, the control unit 232 first positions the substrate stage 206 so that the second mark coincides with the default Z position (for example, the designed focal position). do. After executing the process of measuring the imaging position in the X and Y directions, the control unit 232 executes the process of measuring the focus position (best focus position) described in the second embodiment, and sets the second focus position to the focus position. After positioning the mark, the process of measuring the imaging position in the X and Y directions may be executed again. In other words, if the focal position of the projection optical system 204 is not known in advance, rough measurement of the imaging position in the X and Y directions, measurement of the focal position, and positioning of the second mark at the focal position, Measurements can be made in the order of precise measurement of the imaging position.

After the second mark is positioned at a position having a deviation of 10 [um] from the designed imaging position, the control unit 232 executes the detection process. Specifically, the control unit 232 controls the substrate stage drive mechanism 271 so that the substrate stage 206 is scan-driven in the Y direction while being irradiated with the illumination light 210. The range of scanning drive is 20 [um] if the measurement range is ±10 [um]. For example, the substrate stage 206 is positioned so that the second mark is located at a position having a deviation of -10 [um] in the negative direction from the designed imaging position, and then the substrate stage 206 is shifted in the positive direction by +20 [um]. ] It is sufficient to carry out scanning drive within the scanning range. During this scanning drive period, the control unit 232 takes in signals provided from each photoelectric conversion unit 242 and position information of the substrate stage 206 provided from the measuring instrument 230. Thereby, the control unit 232 can obtain information indicating the relationship between the position Y of the substrate stage 206 in the Y direction and the output of the photoelectric conversion unit 242, as illustrated in FIG. 4(a). The position (PSy) of the substrate stage 206 in the Y direction at which the output of the photoelectric conversion unit 242 has the maximum value is determined by the imaging position in the Y direction of the first mark 250 (H mark 251) and the second mark 260 (H mark 261). The position of the substrate stage 206 in the Y direction coincides with the position of the substrate stage 206 in the Y direction.

Then, from the result of the detection process using the first mark M11 (H mark 251 of the first mark 250), the control unit 232 can obtain measurement data M11y regarding the Y direction according to the following equation.

M11y = PSy - P11y
Here, PSy is the position in the Y direction of the substrate stage 206 at which the output of the photoelectric conversion unit 242 disposed under the second mark P11 (second mark 260) is the maximum value, and the second position from the reference position of the substrate stage 206 is PSy. The distance in the Y direction from mark P11 to H mark 261 is assumed to be P11y.

The measurement data M11y (δy in the formula described later) is approximately equal to the imaging position of the first mark M11 (dy1 in the formula described later). However, the measurement data M11y is based on the position error of the substrate stage 206 (ey, eθ in the formula described later), the position error during manufacturing of the second mark (dy2 in the formula described later), and the quantization error of the photoelectric conversion unit 242. (εy). Although FIG. 4A illustrates the output of one photoelectric conversion unit 242, in the first embodiment, the second mark group 240 outputs four second marks 260 (and four photoelectric conversion units 242). have Therefore, the control unit 232 can obtain measurement data M11y, M12y, M21y, and M22y for the four first marks 250, that is, the first marks M11, M12, M21, and M22y, through one detection process.

Similarly to the above, the control unit 232 obtains measurement data M11x in the X direction from the result of the detection process using the first mark M11 (V mark 252 of the first mark 250) according to the following formula.

M11x = PSx - P11x
Here, the position in the X direction of the substrate stage 206 where the output of the photoelectric conversion unit 242 disposed under the second mark P11 (the second mark 260) has the maximum value is PSx, and the position PSx is the second position from the reference position of the substrate stage 206. The distance in the X direction from mark P11 to V mark 262 is assumed to be P11x. Further, similarly to M11x, the control unit 232 can obtain M12x, M21x, and M22x for the other first marks M12, M21, and M22y. The measurement data in the X direction (δx in the formula described below) also depends on the positional error (ex, eθ) of the substrate stage 206, the positional error (dx2) during manufacturing of the second mark, and the quantization of the photoelectric conversion unit 242. error (εx).

Next, the control unit 232 executes a movement process to control the substrate stage drive mechanism 271 so that the substrate stage 206 moves in the Y direction, as illustrated in FIG. 3(d). The moving distance of the substrate stage 206 in this moving process is 25 [mm], which is the arrangement pitch of the first marks 250. By such movement processing of the substrate stage 206, the second marks P11, P12, P21, and P22 almost match the imaging positions of the first marks M21, M22, M31, and M32. Then, through the same detection process as described above, the control unit 232 obtains measurement data regarding the first marks M21, M22, M31, and M32.

Next, the control unit 232 performs a movement process to control the substrate stage drive mechanism 271 so that the substrate stage 206 moves in the X direction by a movement distance of 25 [mm], as illustrated in FIG. 3(e). and then performs the detection process. The control unit 232 repeats the movement processing and detection processing as described above. The number of detection processes is "the number of measurement points - 1" in both the X and Y directions, so in the first embodiment, the detection process is performed at 3 types of positions in the Y direction and 30 types of positions in the X direction, for a total of 90 positions in the X and Y directions. Performs direction-related detection processing. Furthermore, since four pieces of measurement data are obtained for one location in each of the X and Y directions, a total of 90×4×2=720 pieces of measurement data are obtained. Let these measurement data be (δx, δy).

The control unit 232 uses the 720 pieces of measurement data (δx, δy) obtained as described above to create simultaneous equations in which the imaging position of the first mark is substituted into (Equation 1) to (Equation 11), which will be explained below. is solved by multiple regression analysis.

Here, each variable is defined as follows.

δx(n), δy(n): nth measurement data dx1(i), dy1(i): imaging position of the first mark dx2(j), dy2(j): second mark during mask manufacturing Position error ex(l), ey(l), eθ(l): Positional error of substrate stage during measurement X2(j), Y2(j): Position of second mark εx(n), εy(n): Quantization error of the photoelectric conversion unit SX(l), SY(l): Position of the substrate stage at the time of measurement p: Number of second marks placed on the mask (4 in the first embodiment)
q: Number of measurements (90 times in the first embodiment).

This simultaneous equation is an example. In the above example, the orthogonality of the substrate stage 206 in the X and Y directions and the driving magnification are solved as 0, but for example, the orthogonality of the arrangement of the second marks and the magnification of the arrangement may be solved as 0. The equation can be changed arbitrarily to suit the situation.

The imaging positions dx1 and dy1 of the first mark include the placement error of the first mark, so if you accurately measure the placement error of the first mark in advance, you can subtract the placement error from the imaging position. Therefore, the distortion of the projection optical system can be determined more accurately.

As described above, according to the first embodiment, the imaging characteristics (distortion) of the projection optical system 204 can be measured with high precision without performing exposure and development. Further, according to the first embodiment, by using the sensor SE to repeat the movement process and the detection process, the sensor SE is transferred to the projection area of the inspection area (an area where the inspection area is projected onto its image plane by the projection optical system). ), which is advantageous for cost reduction.

The projection optical system 204 can include an adjustment section that adjusts the imaging characteristics (distortion), and measures the imaging characteristics of the projection optical system 204 periodically or at an arbitrary timing, and adjusts the adjustment section based on the results. The imaging characteristics can be adjusted by

The second embodiment will be described below. Matters not mentioned in the second embodiment may follow the first embodiment. In the first embodiment, the image formation position of the mark in the direction parallel to the image plane of the projection optical system 204 is detected, but in the second embodiment, the image formation position of the mark in the direction parallel to the optical axis of the projection optical system 204 is detected. Detect location. In the second embodiment, the output of the photoelectric conversion unit is acquired while driving the substrate stage 206 in the Z direction.

First, the control unit 232 positions the substrate stage 206 using the substrate stage drive mechanism 271 so that the imaging position of the first mark 250 in the X and Y directions matches the position of the second mark 260 in the X and Y directions. . At this time, the position of the substrate stage 206 in the X and Y directions is such that the position of the second mark 260 in the X and Y directions is the imaging position of the first mark 250 in the X and Y directions measured in the first embodiment. may be determined to match. Here, if the four second marks 260 constituting the second mark group 240 do not match the positions of the four corresponding first marks 250 due to distortion of the projection optical system 204, etc., detection processing is performed individually. All you have to do is

After the positioning in the X and Y directions is completed, the control unit 232 executes detection processing. In the detection process, the substrate stage 206 (second mark 260) is driven in the Z direction with the position of the second mark 260 in the X and Y directions matching the imaging position of the first mark 250 in the X and Y directions. . As a result, the image of the first mark 250 is defocused at the second mark 260, and the amount of light passing through the second mark 260 is reduced. Therefore, as illustrated in FIG. 4B, the control unit 232 can obtain information indicating the relationship between the position Z of the substrate stage 206 in the Z direction and the output of the photoelectric conversion unit 242. The position (PSz) of the substrate stage 206 in the Z direction at which the output of the photoelectric conversion unit 242 has the maximum value is the substrate where the imaging position of the first mark 250 in the Z direction and the position of the second mark 260 in the Z direction match. This is the position of the stage 206 in the Z direction. The control unit 232 obtains this PSz as measurement data. This measurement data (δz in the equation described later) is approximately equal to the imaging position (dz1) of the first mark in the Z direction. However, this includes the manufacturing error (dz2) of the plate 241 on which the second mark 260 is provided, the positional error (ez) of the substrate stage 206, and the quantization error (εz) of the photoelectric conversion unit 242. sell.

Thereafter, the control unit 232 repeats the movement process of moving the substrate stage 206 in the X direction and/or the Y direction and the detection process after the movement process, as in the first embodiment. As a result, four pieces of measurement data are obtained at each of 3×30=90 locations, resulting in a total of 360 pieces of measurement data.

The control unit 232 solves simultaneous equations by substituting the 360 measurement data (δz) obtained as described above into the following (Formula 21) to (Formula 25) by multiple regression analysis.

Here, each variable is defined as follows.

δz(n): nth measurement data dz1(i): Image formation position of the first mark dz2(j): Error in the height direction during plate manufacturing ez(l): Z direction of the substrate stage during measurement position error εz(n): quantization error of the photoelectric conversion unit SX(l), SY(l): position of the substrate stage during measurement p: number of second marks placed on the mask (in the second embodiment 4 marks)
q: Number of measurements (90 times in the second embodiment)
In the second embodiment, the number of second marks 260 constituting the second mark group 240 is four, and correspondingly, the number of photoelectric conversion units 242 is four, but this is only an example, and other The number may be adopted. For example, as shown in FIG. 5(a), it is possible to adopt a configuration in which the number of arrays in the X direction is three and the number of arrays in the Y direction is three. In this case, measurements will be made as shown in Figures 5(b), (c), and (d), and the number of measurements will be 29 times in the X direction and 2 times in the Y direction, with 9 data per time, totaling 522. measurement data can be obtained. The drive error of the substrate stage 206 may be calculated not only in the Z direction but also separately in pitch and roll directions. In addition, the equation may be changed depending on the configuration and situation of the exposure apparatus.

Furthermore, if there is an error in the height direction of the mark surface of the mask 202, that error will be included in the calculated focal position. The calculation results may be corrected based on this.

As described above, according to the second embodiment, the imaging characteristics (focal position) of the projection optical system 204 can be measured with high accuracy without performing exposure and development. Further, according to the second embodiment, by using the sensor SE so as to repeat the movement process and the detection process, the sensor SE is transferred to the projection area of the inspection area (an area where the inspection area is projected onto its image plane by the projection optical system). ), which is advantageous for cost reduction.

The third embodiment will be described below. Items not mentioned in the third embodiment may follow the first embodiment. In the third embodiment, an image sensor (two-dimensional image sensor) is used instead of a photoelectric conversion unit as a light amount sensor. FIG. 6 shows the configuration of an exposure apparatus EX according to the third embodiment. In the third embodiment, an image sensor 300 is provided in place of the second mark group and the photoelectric conversion section. The exposure apparatus EX of the third embodiment may be similar to the exposure apparatus EX of the first embodiment in other respects.

In the third embodiment, there is no need to move the substrate stage 206 in the X direction or the Y direction in the detection process to obtain data as illustrated in FIG. 4(a), so the time required for the detection process can be shortened. can. Furthermore, the third embodiment is also useful in cases where it is difficult to adopt the first embodiment, such as when the arrangement interval of evaluation points for evaluating imaging characteristics such as distortion is narrow.

The image sensor 300 may have an effective area (imaging area) of approximately 26 mm square or more, for example, in order to accommodate a mark arrangement pitch of 25 mm. An optical system may be arranged on the substrate stage 206 to form a reduced or enlarged image of the first mark formed on the image plane of the projection optical system 204 on the imaging plane of the image sensor 300. The size of the effective area of the image sensor 300 can be changed as appropriate depending on required specifications. In order to shorten measurement time, the image sensor 300 may be configured to be able to capture images of more marks at the same time.

A method for measuring distortion of the projection optical system 204 will be described below. First, the control unit 232 controls the substrate stage drive mechanism 271 so that the image sensor 300 is positioned at a position where it can image the four first marks 250 selected from the plurality of first marks 250. . The image sensor 300 generates image data 400 corresponding to the optical image of the first mark 250 formed on its imaging surface and provides it to the control unit 232. Image data 400 is schematically shown in FIGS. 7(a) and 7(b). Image data 400 includes images 401 of four first marks 250. The image 401 of the first mark 250 includes an image 402 of the H mark and an image 403 of the V mark.

The control unit 232 determines the imaging position of the first mark 250 in the X and Y directions by processing the image data 400. The processing of the image data 400 may include, for example, a process of determining the position where the amount of light is the greatest as the imaging position. In this case, when determining the imaging position in the X direction, the imaging positions obtained from each of the portions 404, 405, and 406 of the V mark image 403 may be averaged. Furthermore, when determining the imaging position in the Y direction, the imaging positions obtained from each of the portions 407, 408, and 409 of the H mark image 402 may be averaged. The position in the X direction and the position in the Y direction can be determined for each of the four locations of one image data 400, and a total of eight pieces of measurement data can be obtained.

The control unit 232 can obtain measurement data M11y of the first mark M11 in the Y direction according to the following equation.

M11y = PSy - ISy + IMGy
Here, the position of the substrate stage 206 in the Y direction at the time of imaging by the image sensor 300 is assumed to be PSy, and the distance from the reference position of the substrate stage 206 to the center of the image sensor 300 is assumed to be ISy. Further, the processing result (the distance from the center of the image sensor 300 to the imaging position of the H mark of the first mark M11) is set as IMGy. Then, the movement process of moving the substrate stage 206 with the first mark arrangement pitch (25 [mm]) as the movement distance in the X and Y directions and the subsequent detection process are repeated. As a result, detection processing is performed at 30 types of positions in the X direction and 3 types of positions in the Y direction, a total of 90 positions. Since four pieces of measurement data are obtained for each location in each of the X and Y directions, a total of 90×4×2=720 pieces of measurement data are obtained.

The control unit 232 substitutes the imaging position of the first mark from (Equation 1) to (Equation 11) described in the first embodiment using the 720 pieces of measurement data (δx, δy) obtained as described above. Solve the simultaneous equations using multiple regression analysis.

However, the following variables in the third embodiment differ from those in the first embodiment as follows.

dx2(j), dy2(j): Measurement error due to distortion of the image sensor X2(j), Y2(j): Designed imaging position of the first mark (center coordinate reference of the image sensor)
εx(n), εy(n): Quantization error of image sensor According to the third embodiment, the imaging characteristics (distortion) of the projection optical system 204 can be measured with high precision without performing exposure and development. Can be done.

The fourth embodiment will be described below. Matters not mentioned in the fourth embodiment may follow the second and third embodiments. The exposure apparatus EX of the fourth embodiment may have the same configuration as the exposure apparatus EX of the third embodiment. In the fourth embodiment, the control unit 232 controls the substrate stage drive mechanism so that the image sensor 300 is positioned at a position where it can image the four first marks 250 selected from the plurality of first marks 250. 271. Next, the control unit 232 repeats driving of the substrate stage 206 (image sensor 300) in the Z direction and image acquisition by the image sensor 300. At the focal position (best focus position), the contrast of the image data captured by the image sensor 300 is high, and at the defocused position, the contrast of the image data captured by the image sensor is low. Therefore, the control unit 232 detects the contrast of the image data captured by the image sensor 300, and obtains the position of the substrate stage 206 in the Z direction when the contrast is highest as measurement data.

Thereafter, the control unit 232 repeats the movement process of moving the substrate stage 206 using the first mark arrangement pitch (25 [mm]) as the movement distance in the X and Y directions, and the subsequent detection process. As a result, detection processing is performed at 30 types of positions in the X direction and 3 types of positions in the Y direction, a total of 90 positions. Since four pieces of measurement data are obtained for one location, a total of 360 pieces of measurement data are obtained. The control unit 232 calculates the focal position of the projection optical system 204, the drive error of the substrate stage 206 in the Z direction, and the height of the imaging surface of the image sensor 300 by solving simultaneous equations created based on these measurement data. Separate the error in the horizontal direction.

To create the equation, (Equation 21) to (Equation 25) described in the second embodiment can be used.

However, the following variables in the fourth embodiment differ from those in the second embodiment as follows.

dz2(j): Error in the height direction of the imaging surface of the image sensor εz (n): Quantization error of the image sensor Hereinafter, articles will be manufactured using the exposure apparatus represented by the above-mentioned first to fourth embodiments. A method for manufacturing articles will be explained. The article manufacturing method of one embodiment is suitable for manufacturing articles such as devices (semiconductor elements, magnetic storage media, liquid crystal display elements, etc.), color filters, etc., for example. The manufacturing method includes an exposure step of exposing a substrate coated with a photosensitive agent using the above-mentioned exposure apparatus, and a development step of developing the substrate exposed in the exposure step. The manufacturing method may also include other well-known steps (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The method for manufacturing an article according to the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article compared to the conventional method.

The invention is not limited to the embodiments described above, and various changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, the following claims are hereby appended to disclose the scope of the invention.

EX: Exposure device, IL: Illumination system, 206: Substrate stage, SE: Sensor, 232: Control unit

Claims (13)

An exposure apparatus comprising: an illumination system that illuminates a mask placed on a surface to be illuminated; a projection optical system that projects an image of the mask onto a substrate; and a substrate stage that holds the substrate.
a sensor mounted on the substrate stage;
A control unit that controls the sensor,
The control unit performs a detection process multiple times to detect image formation positions of at least two marks selected from a plurality of marks arranged on the illuminated surface using the sensor, and Between the detection process, a movement process is performed to move the substrate stage on which the sensor is mounted,
The movement of the substrate stage in the movement process includes a portion of at least two marks selected from the plurality of marks in the detection process before the movement process and a part of the plurality of marks selected in the detection process after the movement process. carried out so that a portion of at least two marks selected from the marks are common;
An exposure device characterized by: Configured as a scanning exposure device,
The illumination system illuminates a slit-shaped illuminated area,
the plurality of marks are arranged in the illuminated area;
The exposure apparatus according to claim 1, characterized in that: The imaging position is detected by detecting the imaging position in a direction perpendicular to the optical axis of the projection optical system.
The exposure apparatus according to claim 1 or 2, characterized in that: The imaging position is detected by detecting the imaging position in a direction parallel to the optical axis of the projection optical system.
The exposure apparatus according to claim 1 or 2, characterized in that: the plurality of marks have the same shape,
The sensor includes a plate having a plurality of apertures having a shape similar to the shape of each of the plurality of marks, and a plurality of photoelectric conversion units that detect a luminous flux passing through the plurality of apertures.
The exposure apparatus according to any one of claims 1 to 4, characterized in that: Each of the plurality of marks includes a first sub-mark and a second sub-mark,
Each of the plurality of openings includes a third sub-mark and a fourth sub-mark,
The third sub-mark and the fourth sub-mark are such that when the first sub-mark and the third sub-mark overlap, the second sub-mark and the fourth sub-mark do not overlap, and the second sub-mark When the mark and the fourth sub-mark overlap, the first sub-mark and the third sub-mark are arranged so as not to overlap,
The exposure apparatus according to claim 5, characterized in that: The first sub-mark is a mark extending in a first direction, and the second sub-mark is a mark extending in a second direction different from the first direction.
The exposure apparatus according to claim 6, characterized in that: The sensor includes an image sensor.
The exposure apparatus according to any one of claims 1 to 4, characterized in that: The plurality of marks are arranged at a predetermined arrangement pitch,
The exposure apparatus according to any one of claims 1 to 8, characterized in that: The substrate stage includes a substrate chuck that holds the substrate,
the sensor is located in a different area from the substrate chuck;
The exposure apparatus according to any one of claims 1 to 9. The control unit obtains imaging characteristics of the projection optical system based on the results of the detection processing performed multiple times.
The exposure apparatus according to any one of claims 1 to 10, characterized in that: The control unit adjusts the imaging characteristics of the projection optical system based on the imaging characteristics.
12. The exposure apparatus according to claim 11. an exposure step of exposing a substrate using the exposure apparatus according to any one of claims 1 to 12;
a developing step of developing the substrate exposed in the exposure step;
A method for manufacturing an article, comprising: obtaining an article from the substrate developed in the developing step.

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