JP2012190945A - Exposure device and manufacturing method of device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exposure device which can achieve high-precision focus position calibration while enhancing the throughput excellently.SOLUTION: A mask side mark 8 for focusing is provided on the surface of a mask 1, a photoelectric sensor 10 is provided on a plate stage 5 and a plate side mark 9 for focusing is provided on the photoelectric sensor 10. The mask side mark 8 for focusing is illuminated with exposure light 7, and a light beam passed through the mask side mark 8 for focusing is made incident onto the photoelectric sensor 10 through a projection optical system 3 and the plate side mark 9 for focusing. Change in the focus position of the projection optical system 3 is detected based on a signal from the photoelectric sensor 10 obtained when the plate stage 5 is shaken on a plane orthogonal to the optical axis direction of the projection optical system 3 and the position signal of the plate stage 5.

Description

  The present invention relates to a focal position detection method for an exposure apparatus.

  In recent years, in order to increase the definition of liquid crystal televisions and the like, there has been a need for imaging with high resolving power in a projection exposure apparatus due to the demand for pattern miniaturization.

  In an exposure apparatus, an effective high-precision automatic focusing position alignment method for aligning the plate surface with the focusing position (image plane of the projection optical system) is an important theme.

  In this type of projection exposure apparatus, the in-focus position is affected by a change in the ambient temperature of the projection optical system, a change in atmospheric pressure, a temperature increase due to light applied to the projection optical system, or a temperature increase due to heat generated by the apparatus including the projection optical system. Must move and correct this.

  As means for correcting this, TTL autofocus using a light beam via a projection optical system is known.

  In TTL autofocus, slit-shaped mask-side focusing marks are formed in portions other than the circuit pattern of the mask, and light having the same wavelength as the exposure light from the illumination means is masked with the mask mounted on the mask stage. Irradiate the side focus mark.

  Then, the light passing through the slit of the mask-side focusing mark is directed onto the plate stage via the projection optical system, and is received by the photoelectric sensor through the slit of the plate-side focusing mark placed on the plate stage.

  Then, the plate stage is placed on the optical axis of the projection optical system so that the position where the light passing through the slit on the mask stage side focusing mark is imaged via the projection optical system matches the slit position on the plate stage focusing mark. A plane perpendicular to the direction is driven in a direction perpendicular to the slit of the focusing mark. By detecting the position indicating the center of gravity of the light intensity signal from the photoelectric sensor at this time, the plate stage is driven to a position where the imaging position and the plate stage side in-focus mark are aligned.

  The plate stage is moved up and down in the optical axis direction of the projection optical system to change the position of the plate-side focusing mark and the photoelectric sensor, and the position indicating the center of gravity of the light intensity output from the photoelectric sensor at this time is detected. Thus, this position is set as the in-focus position of the projection optical system.

  When detecting the in-focus position of the projection optical system, a range (TTL autofocus detection range) in which the plate stage is driven in the optical axis direction of the projection optical system is set to a predetermined range in advance.

  At this time, for example, if the change in the focus position of the projection optical system due to a temperature change or the like greatly exceeds the detection range, the detection becomes impossible. For this reason, conventionally, a slightly wider detection range is defined, and the plate stage is moved up and down within the detection range.

  However, when the change in the in-focus position of the projection optical system is small, TTL autofocus detection is performed in a useless area, resulting in a problem that throughput is reduced.

  Therefore, in Patent Document 1, the detection range in which the plate stage is moved up and down in the optical axis direction of the projection optical system is set not to be so wide but to an appropriate size detection range, and the image plane variation accompanying the environmental change such as a temperature change by the calculation means. Is calculated based on a preset function, and the in-focus position based on the calculation result is set as a temporary in-focus position, and the plate stage is moved up and down within the detection range based on the temporary in-focus position.

JP-A-5-182895

  However, the in-focus position obtained by the calculation is actually TTL depending on the measurement error of the data used for the calculation (exposure dose, exposure time, mask transmittance, temperature, humidity, atmospheric pressure, etc.) and correction coefficient error. There is a difference from the in-focus position detected by autofocus measurement. Therefore, it is necessary to perform TTL autofocus measurement within the measurement range that takes into account the data measurement error and correction coefficient error used in the calculation, and it takes extra time if the calculation of the in-focus position is correct, and retry measurement. May occur.

  In view of such problems of the prior art, the object of the present invention is to obtain an error between the in-focus position obtained by calculation before TTL autofocus and the in-focus position detected by TTL autofocus, and to obtain an optimum TTL autofocus. An object of the present invention is to provide an exposure apparatus with high throughput by obtaining a focus measurement range.

In order to achieve the object, an exposure apparatus according to the present invention comprises:
A mask side focusing mark 8 is provided on the mask 1 surface, a photoelectric sensor 10 is provided on the plate stage 5, and a plate side focusing mark 9 is provided on the photoelectric sensor 10,
The exposure light 7 illuminates the mask-side focusing mark 8, and the light beam that has passed through the mask-side focusing mark 8 is incident on the photoelectric sensor 10 via the projection optical system 3 and the plate-side focusing mark 9. The change of the in-focus position of the projection optical system 3 is detected based on the signal of the photoelectric sensor 10 obtained when the plate stage 5 is swung on a plane orthogonal to the optical axis direction of the projection optical system 3. To do.

  An exposure apparatus that takes a short time to measure the in-focus position can be provided.

It is the figure which showed the structure of this embodiment. It is the figure which showed the mark for focusing. It is TTL autofocus explanatory drawing. It is a figure of the measurement signal at the time of TTL autofocus. It is a figure of the measurement signal at the time of slit position alignment. It is a flowchart of a preparation stage. It is a flowchart of a device manufacturing stage.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[First embodiment]
First, the structure of the exposure apparatus according to the first embodiment of the present invention will be described with reference to FIGS.

  The mask 1 is held on the mask stage 2. When the circuit pattern on the mask 1 is transferred, the mask 1 is illuminated with the circuit pattern by the illumination optical system 6, and the circuit pattern on the mask 1 is held on the plate stage 5 by the projection optical system 3. An image is formed on the resist and an exposure process is performed.

  A mask-side focusing mark 8 is provided on the surface of the mask 1 separately from the circuit pattern, and includes a light shielding portion 8a and a slit 8b. Further, a plate-side focusing mark 9 whose height is substantially coincident with the upper surface of the plate 4 is disposed at a position adjacent to the plate 4. The plate-side focusing mark 9 has a light shielding portion 9 a and a slit 9 b, and a photoelectric sensor 10 is provided below the plate-side focusing mark 9. The intensity signal of the light incident on the photoelectric sensor 10 is input to the automatic focusing control system 22 via the signal line. Here, with respect to the arrangement of the slit 8a of the mask-side focusing mark 8 and the slit 9a of the plate-side focusing mark 9, as shown in FIG. 2, the light that has passed through the long slit in the X direction and the long slit in the Y direction. The astigmatism of the projection optical system 3 can be measured by determining the difference between the in-focus positions of the X-direction slit and the Y-direction slit.

  The plate stage 5 is movable in the optical axis direction (Z direction) of the projection optical system 3 and a plane (XY plane) orthogonal to the optical axis, and can be rotated around the X axis, the Y axis, and the Z axis.

  11 is a light projecting optical system, and 12 is a detection optical system. These plates detect the position of the plate-side focusing mark 9 surface (or the upper surface of the plate 4) in the optical axis direction (Z direction) of the projection optical system 3. Surface position detecting means is configured.

  A plurality of light beams are projected from the light projecting optical system 11. Each light beam projected from the light projecting optical system 11 is composed of non-exposure light, and is composed of light that does not sensitize the photoresist on the plate 4. The plurality of light beams are respectively collected and reflected on the surface of the plate-side focusing mark 9. The reflected light beam enters the detection optical system 12. Although not shown, position detection line sensors are arranged in the detection optical system 12 in correspondence with the respective reflected light beams. The reflection point of each light beam on the light receiving surface of the line sensor and the plate-side focusing mark 9 surface is configured to be substantially conjugate.

  The positional deviation signal of the incident light beam on the line sensor in the detection optical system 12 is calculated by the surface position detection system 21 as the positional deviation in the Z direction of the surface of the plate-side focusing mark 9, and the automatic focusing control system 22. Is input.

  The automatic focusing control system 22 gives a command signal to the stage control system 23 through a signal line as driving means for driving the plate stage 5 on which the plate-side focusing mark 9 is stacked. The stage control system 23 drives the plate stage 5, monitors the position of the plate stage 5 at the time of driving, and inputs the monitor result to the automatic focusing control system 22 through a signal line.

  Further, the automatic focusing control system 22 includes the intensity of light from the photoelectric sensor 10 when the slit positioning described later is performed, the position signal of the plate stage 5, and threshold value data used for determining the focusing position change. A memory capable of storing a plurality of files is provided.

  Next, TTL autofocus will be explained.

  First, the case where the plate-side focus mark 9 is at the focus position of the mask-side focus mark 8 will be described with reference to FIG. The exposure light 7 that has passed through the mask-side focusing mark 8 is condensed on the plate-side focusing mark 9 via the projection optical system 3, and all the light beams pass through the plate-side focusing mark, thereby producing a photoelectric sensor. The light intensity signal by 10 is maximized.

  Next, with respect to the case where the plate-side focusing mark 9 is at a position shifted from the focusing position of the mask-side focusing mark 8 in the optical axis direction (Z direction) of the projection optical system, FIG. It explains using. At this time, since the plate-side focusing mark 9 is not in the in-focus position, the exposure light 7 is applied to the plate-side focusing mark 9 as a light beam spreading through the projection optical system 3. At this time, part of the exposure light is directed to the light shielding portion 9a of the plate-side focusing mark 9, and the entire light beam cannot pass through the slit 9b.

  That is, the TTL autofocus is performed when the plate-side focusing mark 9 is defocused (light is weak) and the focus position (light is strong) of the mask-side focusing mark 8 via the projection optical system 3. The focus position of the plate-side focusing mark 9 is detected by utilizing the difference in the light intensity signal of the photoelectric sensor 10.

  Furthermore, the procedure of the TTL autofocus method and the calculation method of the focus position will be described. First, the mask stage 2 is moved so that the exposure light 7 strikes the mask-side focusing mark 8, and the plate stage is moved so that the imaging position of the mask-side focusing mark 8 and the plate-side focusing mark 9 are aligned. To do. Next, the plate stage 5 is shaken in the optical axis direction (Z direction) of the projection optical system 3. At this time, the stage control system 23 monitors the position of the projection optical system 3 of the plate stage 5 in the optical axis direction (Z direction) and outputs a signal to the automatic focusing control system 22. The photoelectric sensor 10 outputs a light intensity signal to the automatic focusing control system 22. FIG. 4 shows a signal input to the automatic focusing control system 22, and the automatic focusing control system 22 can calculate the focusing position Z0 by applying the following methods (a) to (d) from the signal shown in FIG. It is.

  (A) The Z position of the plate stage where the light intensity is maximum is set as the in-focus position Z0.

  (B) A certain slice level 30 is set with respect to the maximum intensity of light, and Z0 = (Z1 + Z2) / 2 from the Z1, Z2 position of the plate stage indicating the output of the slice level 30, and the in-focus position Z0 Is calculated.

  (C) The center of gravity is calculated with respect to the light intensity and the Z position of the plate stage, and the center of gravity is set as the in-focus position Z0.

  (D) A quadratic function approximation (y = A · X · X + B · X + C) is performed on the light intensity and the Z position of the plate stage, and the in-focus position Z0 is calculated as Z0 = −B / 2A. It is also desirable to set a certain percentage of slice levels 30 and perform a second order approximation from the position of the plate stage showing the light intensity at slice level 30 or higher.

  Next, slit positioning necessary for TTL autofocus will be described.

  First, FIG. 3- (c) is used in the case where the plate-side focusing mark 9 is shifted from the focusing position of the mask-side focusing mark 8 in the direction orthogonal to the optical axis direction of the projection optical system. I will explain.

  At this time, since the plate-side focusing mark 9 is not at the imaging position, the exposure light 7 that has passed through the mask-side focusing mark 8 is shifted from the plate-side focusing mark 9 via the projection optical system 3. A portion of the exposure light is focused on the light shielding portion 9a of the plate-side focusing mark 9, and the entire light beam cannot pass through the slit 9b. In other words, even if TTL autofocus is performed at this position, measurement cannot be performed because the plate-side focusing mark is illuminated. In particular, at the in-focus position, since the light is condensed at a position shifted from the slit 9a, there is a possibility that the light is weak at the in-focus position and the light is increased at the defocus position. Requires slit alignment.

  The slit alignment is performed when the position of the plate-side focusing mark 9 deviates from the focusing position (light is strong) of the mask-side focusing mark 8 via the projection optical system 3 (light is weak). This is done by utilizing the difference in the light intensity signal of the photoelectric sensor 10. Also, even if the slit alignment is at the defocus position (the position where the light spreads), the light intensity will not be reversed when the slit position is not correct, as in TTL autofocus. , Can be measured before TTL autofocus.

  Further, a procedure for adjusting the slit position and a method for calculating the optimum position will be described. First, the mask stage 2 is moved so that the exposure light 7 strikes the mask-side focusing mark 8, and the plate stage so that the imaging position of the mask-side focusing mark 8 and the plate-side focusing mark 9 are substantially aligned. Move 5. Next, the plate stage 5 is driven in a direction (XY direction) orthogonal to the optical axis of the projection optical system 3. At this time, the stage control system 23 monitors the X or Y position of the plate stage 5 and outputs a signal to the automatic focusing control system 22. The photoelectric sensor 10 outputs a light intensity signal to the automatic focusing control system 22. At this time, the plate stage 5 is driven in a direction orthogonal to the slit. For example, when measuring with a slit long in the Y direction, the plate stage 5 is driven in the X direction to measure the slit position. Further, it is not always necessary to drive the plate stage 5 in a direction orthogonal to the slit. For example, in the case of an oblique slit inclined at 45 °, the plate stage 5 is driven to be orthogonal to the slit in the oblique direction simultaneously with the X axis and the Y axis. Instead, measurement may be performed by driving in the X-axis direction or the Y-axis direction.

  The automatic focusing control system 22 can calculate the optimum position from the X or Y position signal of the plate stage 5 and the light intensity signal by applying the following method. As the calculation method, the same calculation methods (a) to (d) as in the above-described TTL autofocus can be applied.

  Next, a calibration method for aligning the plate 4 with the in-focus position will be described. First, the plate-side focus mark 9 is moved to the focus position by TTL autofocus. Next, the position of the plate-side focus mark 9 is measured by the plate surface position detection system 21, and the measurement position is set as the focus position. Then, the upper surface of the plate 4 is moved to the measurement position of the surface detection system 21, the position of the upper surface of the plate 4 is measured by the plate surface position detection system, and the plate stage is moved in the Z direction by the difference from the in-focus position. Thus, the upper surface of the plate 4 can be moved to the in-focus position of the projection optical system.

  Next, a method for detecting a change in the focus position of the projection optical system 3 from a signal at the time of slit alignment will be described.

  As a preparatory stage, the intensity signal of the light from the photoelectric sensor 10 obtained when the slit alignment measurement is performed at the in-focus position of the projection optical system 3 and the position defocused from the in-focus position. A plurality of signals from the stage control system 23 are acquired and stored in the automatic focusing control system 22.

  FIGS. 5A to 5C show the X axis or Y axis position of the plate stage with the intensity of light from the photoelectric sensor when the plate stage is shaken in the optical axis direction of the projection optical system as the vertical axis. It is a graph when taken on the horizontal axis.

  The signal of (a) in FIG. 5 is a graph obtained by measuring the position of the plate-side focusing mark at the in-focus position, and the signals of (b) and (c) in FIG. 5 are graphs measured at positions deviating from the in-focus position. . (B) is on the apparatus (illumination side) in the optical axis direction (Z direction) of the projection optical system from (a), and (c) is the optical axis direction (Z direction) of the projection optical system from (a). Are both below the apparatus (the direction in which the exposure light travels), both of which are the same distance from the position acquired at the in-focus position (a). At this time, since the graphs in (b) and (c) are approximately the same, whether the in-focus position of the projection optical system has shifted in the upper direction of the apparatus (illumination side) or in the lower direction of the apparatus (direction in which exposure light travels) Are treated the same. However, when there is aberration in the projection optical system, a difference in signal occurs between (b) and (c). If the aberration of the projection optical system does not affect the manufacturing of the device and the signals at the focus position are different between (b) and (c), a signal with a large difference from the signal at the focus position will be described later. Used for threshold calculation.

  In the signal of FIG. 5A measured at the in-focus position, the exposure light 7 that has passed through the mask-side focusing mark 8 is condensed on the plate-side focusing mark 9 via the projection optical system 3, and all of the signals are collected. When the light beam passes through the plate-side focusing mark 9 and the light intensity signal from the photoelectric sensor 10 becomes maximum, and the light beam deviates in the direction orthogonal to the optical axis (XY direction), the light is emitted to the plate-side focusing mark. Therefore, the signal from the photoelectric sensor 10 becomes low.

  5B and 5C measured at a position deviated from the in-focus position, the exposure light 7 that has passed through the mask-side in-focus mark 8 is converted into a light beam that has spread through the projection optical system 3, and the plate side. The focusing mark 9 is irradiated. At this time, part of the exposure light is directed to the plate-side focusing mark 9, and the entire light beam cannot pass through the slit 9a, and the maximum amount of light is lower than that in (a), and is orthogonal to the optical axis. Even if it is shifted in the direction (XY direction), since the exposure light 7 spreads, a part of the exposure light passes through the plate-side focusing mark 9, and the minimum light quantity becomes higher than that in (a). That is, since there is a difference in the signal at the time of the slit alignment measurement between when focused and when deviated from focus, a change in the focused position is detected using this.

  For example, the following method can be applied as a method for detecting a change in focus position.

  (E) When the difference between the maximum value and the minimum value of the light intensity becomes smaller than the threshold value than the value measured at the in-focus position recorded in the automatic in-focus control system 22, it is deviated from the in-focus position. To detect.

  (F) When the maximum value of the light intensity is smaller than the threshold value measured at the in-focus position recorded in the automatic in-focus control system 22, it is detected that the light has shifted from the in-focus position.

  (G) When the minimum value of the light intensity becomes larger than the threshold value measured at the in-focus position recorded in the automatic in-focus control system 22, it is detected that the light has shifted from the in-focus position.

  The threshold values in the respective detection methods (e) to (g) are arbitrarily determined according to the measurement width and the defocus allowable value when the plate stage is moved in the optical axis direction of the projection optical system to measure the in-focus position.

  If the signal obtained by the slit alignment measurement at the time of device manufacture changes more than the threshold when measured at the in-focus position, the signal is focused more than the deviation from the in-focus position where the threshold is measured. It can be detected that the position has changed. That is, it is possible to detect a change in the focus position from the signal at the time of measuring the slit alignment position.

  Next, a specific process in the present embodiment will be described with reference to a preparatory stage flowchart in FIG. 6 and a device manufacturing stage flowchart in FIG. The improvement of the throughput using the signal at the time of slit alignment measurement in this embodiment is to skip the focus position measurement when the change of the focus position detected by the signal at the time of slit position measurement is less than 5 [um]. When the change in focus position is less than 20 [um], the time required for the focus position is shortened by narrowing the focus position measurement range.

  First, as a preparation stage, slit alignment measurement is performed at a position shifted by ± 5 [um] in the optical axis direction (Z direction) of the projection optical system and a position shifted by ± 20 [um] from the focus position. Signal acquisition is performed and a threshold value is determined. In the flowchart of FIG. 6, first, the mask stage 2 is moved so that the exposure light 7 strikes the mask side focus mark 8, and the focus position of the mask side focus mark 8 and the plate side focus mark 9 are substantially omitted. The plate stage 5 is moved so as to fit, and slit alignment measurement is performed (S101). Then, based on the result of the slit alignment measurement, the plate stage 5 is driven, and the focus position of the mask side focus mark 8 and the focus position of the plate side focus mark 9 are the optical axes of the projection optical system. The slit alignment is finished within a plane (XY plane) orthogonal to (S102).

  Subsequently, the TTL autofocus measurement is moved (S103), the plate stage 5 is driven in the Z-axis direction based on the TTL autofocus detection result, and the focus position of the mask side focus mark 8 and the plate side focus are adjusted. The focus mark 9 is aligned (S104).

  Subsequently, the slit alignment measurement is performed, and the light intensity signal of the photoelectric sensor and the position signal of the plate stage 5 at this time are stored in the focusing control system 22 (S105).

  Next, it moves from the in-focus position to a position shifted by +5 [um], −5 [um], +20 [um], −20 [um] in the optical axis direction (Z direction) of the projection optical system 3 (S106). Then, the slit position is measured and the light intensity signal of the photoelectric sensor 10 and the position signal of the plate stage 5 are stored in the focusing control system 22 (S107). The difference between the signal acquired at the in-focus position and the signal acquired at a position shifted by 5 [um] from the in-focus position is defined as a threshold T1, and the signal acquired at the in-focus position and a position shifted by 20 [um] from the in-focus position. The difference from the signal acquired in step S2 is stored as a threshold value T2 (S108). Here, the signals of +5 [um] and −5 [um] are substantially the same, and the signals of +20 [um] and −20 [um] are substantially the same, but the projection optical system 3 has an aberration. A difference occurs in the signal. If there is an aberration that does not affect the manufacture of the device and the focus position signal differs in the defocus direction, the larger difference may be used as the threshold value. That is, when −20 [um] is larger than +20 [um] than the signal acquired at the in-focus position, the signal difference at −20 [um] is used as the threshold T2.

  Subsequently, the flow of the device manufacturing stage will be described with reference to FIG.

  ΔF1 is set to an initial value (S201). ΔF1 is the position in the Z direction of the plate stage 5 when the plate 4 is subjected to exposure processing, and the initial value may be a temporary position that is a substantially in-focus position, but if there is ΔF1 that was previously exposed, the value is It is desirable to take over.

  Subsequently, the plate 4 is supplied and held on the plate stage 5 (S202).

  Next, the plate stage 5 is driven to the position of ΔF1 in the Z direction (S203), and slit alignment measurement is performed (S204). Then, the signal at the time of slit alignment measurement (S204) is compared with the signal at the time of slit alignment measurement (S105) at the in-focus position stored in the automatic focusing processing system 22 in the preparation stage (S205), If the signal difference is less than the threshold value T1, the current Z position is within ± 5 [um] from the in-focus position, so the TTL autofocus measurement is skipped and the surface position of the plate-side in-focus mark 9 is detected (S211). ) If the signal difference in S204 is less than the threshold value T2, the in-focus position is shifted within a range of ± 20 [um], so the measurement range at the time of in-focus position measurement is set to ± 20 [um] (S207). When the signal difference is larger than the threshold value T2, the in-focus position is shifted by ± 20 [um] or more, so the measurement range at the time of in-focus position measurement is set to ± 100 [um] (S206), and the slit alignment measurement ( From the detection result of S204), the plate-side focusing mark 9 is moved to the optimum position (S208), and TTL autofocus is performed (S209). Further, based on the detection result of TTL autofocus (S209), the plate stage 5 is driven in the Z direction to move the plate-side focusing mark 9 to the in-focus position, and the value of ΔF1 is set in the Z direction of the plate stage 5. Update with the position (S210).

  Then, the plate-side focusing mark 9 is measured by the plate surface position detecting means, and the measured position is set as the focusing position (S211). Subsequently, the plate stage 5 is driven so that the plate 4 can be measured by the plate surface position detecting means. Therefore, the upper surface of the plate 4 is measured by the plate surface position detecting means, and the plate stage 5 is driven in the Z direction so that the upper surface of the plate 4 comes to the in-focus position (S212).

  Thus, since the upper surface of the plate 4 is at the in-focus position, exposure processing is performed (S213).

  Subsequently, a change amount ΔF2 of the in-focus position by the exposure process is calculated during the exposure process, and ΔF1 is updated with the calculated in-focus position (S214). Here, the amount of change ΔF2 of the in-focus position is calculated by the following equation: ΔF2 = K · τ · E · t0 / t, and ΔF2 is added to the value of ΔF1 (ΔF1 = ΔF1 + ΔF2). Here, K is the in-focus position change coefficient of the projection optical system 3, τ is the transmittance of the mask 1, E is the amount of light irradiated per unit time from the illumination system 6, and t0 is the irradiation time of the exposure light 7 from the illumination system 6. , T is the total exposure interval time.

  Subsequently, the plate 4 that has undergone the exposure process is collected (S215). If there is an unprocessed plate, the process returns to S202 to receive and continue the next plate, and if there is no plate to be processed, the process ends.

  In this embodiment, as described above, the circuit pattern on the mask 1 surface is projected onto the resist on the upper surface of the plate 4 by the projection optical system 3 so that the upper surface of the plate 4 is positioned at the in-focus position of the projection optical system 3. Exposure to manufacture liquid crystal display devices and semiconductor devices.

  In the TTL autofocus system according to the present invention, as disclosed in JP-A-1-286418, the light transmitted through the slit on the mask surface is reflected using a mirror on the plate surface through the projection optical system, and again the mask surface. A method of detecting light intensity through the upper slit is also applicable.

  As described above, according to the present embodiment, it is possible to determine the optimum measurement range of the TTL autofocus by detecting the change of the focus position using the slit alignment signal, thereby improving the throughput. be able to.

[Second Embodiment]
Next, the case where the illumination of the illumination system 6 varies depending on the device to be manufactured in the exposure apparatus of the present embodiment will be described. Since the TTL autofocus of the present embodiment is performed according to the light intensity, the intensity of the light received by the photoelectric sensor 10 changes when the illumination condition such as the exposure light amount is changed. For this reason, when the illumination condition used in the preparation stage is different from the illumination condition when manufacturing the device, the threshold value obtained in the preparation stage cannot be used. As described above, when each device has an illumination condition, a threshold value is calculated for each illumination condition, and the threshold value and a signal at the time of measuring the slit position at the in-focus position are stored in the automatic focusing control system 22 as a key. Just do it.

  In this embodiment, the illumination light quantity detection system 20 is provided, and the illumination light quantity detection system 20 is not shown, but the light intensity of the exposure light 7 from the illumination system 6 is measured by a light quantity sensor provided in the illumination system 6. Output to the automatic focusing control system 22.

  In the preparation stage, the threshold value and the signal at the time of slit alignment measurement at the in-focus position are stored in the auto-focus control system 22 using the light intensity signal from the illumination system 6 as a key. Using the light intensity signal from the detection system 20 as a key, a change in the focus position is detected from the slit position measurement using the threshold value and the signal at the time of slit position measurement at the focus position.

  As described above, according to the present embodiment, even when the exposure light 7 from the illumination optical system 6 is different for each device, the change of the in-focus position is detected by using the slit alignment signal. The optimum measurement range of autofocus can be determined, and the throughput can be improved.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

DESCRIPTION OF SYMBOLS 1 Mask 2 Mask stage 3 Projection optical system 4 Plate 5 Plate stage 6 Illumination optical system 7 Exposure light 8 Mask side focusing mark 9 Plate side focusing mark 10 Photoelectric sensor 11 Light projection optical system 12 Light reception optical system 20 Illumination light quantity Detection system 21 Surface position detection system 22 Automatic focusing control system 23 Stage control system

Claims (4)

In an exposure apparatus that projects a circuit pattern on a mask surface supported by a mask stage illuminated by exposure light from an illumination optical system onto a plate surface placed on the plate stage by a projection optical system,
A mask side focusing mark is provided on the mask surface, a photoelectric sensor is provided on the plate stage, and a plate side focusing mark is provided on the photoelectric sensor,
The exposure light illuminates the mask-side focusing mark, and the light beam that has passed through the focusing mark on the mask surface passes through the projection optical system and the focusing mark on the plate surface to a photoelectric sensor. Incident,
The projection optical system is focused on the basis of an intensity signal of light from the photoelectric sensor and a position signal of the plate stage obtained when the plate stage is swung on a plane orthogonal to the optical axis direction of the projection optical system. An exposure device that detects changes in position. The photoelectric sensor illuminates the mask-side focusing mark with the exposure light and passes the light beam that has passed through the focusing mark on the mask surface via the projection optical system and the focusing mark on the plate surface. Incident on
An in-focus position of the projection optical system is detected based on an intensity signal of light from the photoelectric sensor obtained when the plate stage is shaken in the optical axis direction of the projection optical system and a position signal of the plate stage. 2. The exposure apparatus according to claim 1, wherein a driving width in the optical axis direction of the projection optical system of the plate stage is controlled based on a detection result of a change in the focus position. An illumination light amount detection system for detecting an illumination condition of the illumination optical system, illuminating the mask-side focusing mark with the exposure light, and a light beam that has passed through the focusing mark on the mask surface; Incident to the photoelectric sensor through the system and the focusing mark on the plate surface,
The illumination condition of the illumination optical system, the intensity signal of the light from the photoelectric sensor, the position signal of the plate stage, and the position signal of the plate stage obtained when the plate stage is shaken on a plane orthogonal to the optical axis direction of the projection optical system The exposure apparatus according to claim 1, wherein a change in a focus position of the projection optical system is detected based on an illumination condition signal of an illumination system.   A device manufacturing method for manufacturing a device, comprising the step of exposing a substrate by the exposure apparatus according to any one of claims 1 to 3.