JP7336343B2 - Exposure apparatus, exposure method, and article manufacturing method - Google Patents

Description

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

An exposure apparatus that exposes a plurality of shot areas on a substrate by scanning the substrate with light from a projection optical system is known as one of the apparatuses used in the manufacturing process (lithography process) of semiconductor devices and the like. ing. During scanning exposure of each shot area, the exposure apparatus measures the surface height of the substrate (focus measurement) prior to light irradiation. Height adjustment (focus/leveling control) of the substrate for placement on the plane is performed.

By the way, in each shot area of the substrate, a pattern structure having a step distribution (for example, an uneven shape) may be formed. In this case, frequently changing the height of the substrate so as to follow the pattern structure may cause a delay in adjusting the height of the substrate, making it difficult to perform focus/leveling control with high accuracy. Japanese Patent Application Laid-Open No. 2002-200000 describes a method of performing focus/leveling control based on the result of measuring the step distribution (step data) of a pattern structure formed in a shot area in advance and correcting the result of focus measurement with the step distribution. is disclosed.

JP-A-9-45608

In the exposure apparatus, obtaining step data each time the substrate or lot is changed is disadvantageous in terms of throughput. Therefore, if the pattern structure of each shot area is the same even if the substrate or lot is changed, it is preferable to apply the step distribution obtained in the past. However, the substrate used to acquire the step distribution and the substrate to be exposed may have different distortions due to the holding state of the substrate stage, etc. Therefore, the step distribution obtained in the past may It can be difficult to properly determine whether the

Accordingly, an object of the present invention is to provide an advantageous technique for appropriately determining whether or not a step distribution obtained in the past is applicable.

To achieve the above object, an exposure apparatus as one aspect of the present invention is an exposure apparatus that exposes a plurality of areas on a substrate, each area having a common pattern structure, wherein the surface height of each area is and a control unit for controlling exposure of each region, wherein the control unit causes the measurement unit to measure a plurality of sample regions selected from the plurality of regions. A step distribution of the pattern structure is obtained as a first distribution by performing a process of removing components of a predetermined order or less from the surface height distribution, and a second distribution of steps of the pattern structure obtained in the past is obtained. controlling the exposure of each region while adjusting the height of the substrate based on the second distribution and the measurement result of the measurement unit when the variation of the first distribution with respect to the distribution is equal to or less than a threshold; characterized by

Further objects or other aspects of the present invention will be made clear by preferred embodiments described below with reference to the accompanying drawings.

According to the present invention, for example, it is possible to provide an advantageous technique for appropriately determining whether or not a step distribution acquired in the past is applicable.

Schematic diagram showing the configuration of an exposure apparatus A diagram showing the arrangement of multiple measurement points in the measurement unit FIG. 4 is a diagram showing the positional relationship between a shot area to be scanned and exposed, an irradiation area irradiated with exposure light, and a plurality of measurement points for surface height measurement; A diagram showing an arrangement example of sample shot areas on a substrate and an arrangement example of measurement target points in each shot area. A diagram showing conventional processing for obtaining a correction distribution FIG. 4 is a diagram showing processing of the first embodiment for acquiring a correction distribution; A diagram showing an arrangement example of sample shot areas selected to obtain correction distributions and confirmation distributions. FIG. 10 is a diagram showing the processing of the first embodiment for obtaining a confirmation distribution; FIG. 10 is a diagram showing the process of the second embodiment for obtaining a confirmation distribution; Diagram showing how to modify the correction distribution Flowchart showing the flow of scanning exposure processing A plan view of the board showing the points to be measured for the surface height

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In addition, the following embodiments do not limit the invention according to the scope of claims. Although multiple features are described in the embodiments, not all of these multiple features are essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant description is omitted.

<First embodiment>
A first embodiment according to the present invention will be described. The exposure apparatus 100 of the present embodiment is a so-called step-and-scan type scanning exposure apparatus that exposes the substrate 15 while scanning the exposure light (slit light, pattern light) emitted from the projection optical system 14. is. In the following description, a direction parallel to the optical axis of the projection optical system 14 is the Z direction, and two directions that are orthogonal to each other on a plane perpendicular to the Z direction are the X direction and the Y direction. Also, the scanning direction of the mask 12 and the substrate 15 (that is, the scanning direction of the irradiation area 21 on the substrate) is the Y direction.

[Configuration of exposure device]
FIG. 1 is a schematic diagram showing the configuration of an exposure apparatus 100 according to the first embodiment. The exposure apparatus 100 includes an illumination optical system 11, a mask stage 13, a projection optical system 14, a substrate stage 16, a measurement section 17, a first detection section 18, a second detection section 19, and a control section 20. including. The control unit 20 includes a CPU and memory, and controls the entire exposure apparatus 100 . That is, the controller 20 controls the process of transferring the pattern formed on the mask 12 to the substrate 15 (scanning and exposing the substrate 15).

The illumination optical system 11 uses a light-shielding member such as a masking blade included therein to shape light emitted from a light source (not shown) such as an excimer laser into, for example, a strip-shaped or arc-shaped slit light elongated in the X direction. A portion of the mask 12 is illuminated with light. The mask 12 and substrate 15 are held by a mask stage 13 and a substrate stage 16, respectively, and placed at optically nearly conjugate positions (object plane and image plane of the projection optical system 14) through the projection optical system 14, respectively. be done. The projection optical system 14 has a predetermined projection magnification, and projects the pattern formed on the mask 12 onto the substrate with slit light. A region of the substrate 15 onto which the pattern of the mask 12 is projected (a region irradiated with slit light) is sometimes referred to as an irradiation region 21 below.

The mask stage 13 and the substrate stage 16 are configured to be movable in a direction (for example, Y direction) perpendicular to the optical axis of the projection optical system 14 (the optical axis of the slit light). Relative scanning is performed at a speed ratio corresponding to the projection magnification. Thereby, the pattern of the mask 12 can be transferred to the shot area 15a on the substrate by moving (scanning) the irradiation area 21 on the substrate. By sequentially repeating such scanning exposure for each of the plurality of shot areas 15a on the substrate, the exposure processing for one substrate 15 can be completed.

The first detection unit 18 includes, for example, a laser interferometer, irradiates a laser beam toward the reflector 13a provided on the mask stage 13, and determines the position of the mask stage 13 based on the laser beam reflected by the reflector 13a. Detect location. Further, the second detection unit 19 includes, for example, a laser interferometer, irradiates a laser beam toward a reflector 16a provided on the substrate stage 16, and detects the substrate stage based on the laser beam reflected by the reflector 16a. 16 positions are detected. The control unit 20 relatively drives the mask stage 13 and the substrate stage 16 based on the detection results of the first detection unit 18 and the second detection unit 19, thereby controlling the relative position between the mask 12 and the substrate 15 in the XY directions. can do. In the present embodiment, the first detection unit 18 and the second detection unit 19 are composed of laser interferometers, but are not limited to this, and may be composed of encoders, for example.

The measurement unit 17 measures the surface height of the shot area 15a of the substrate 15 while the substrate 15 (substrate stage 16) is moving. That is, the measurement unit 17 can measure the surface height distribution of the shot area 15 a of the substrate 15 . The measurement unit 17 of this embodiment is of an oblique incidence type that irradiates the substrate 15 with light obliquely. 17b.

The light projection system 17a can include a light source 70, a collimator lens 71, a slit member 72, an optical system 73, and a mirror 74, for example. The light source 70 has, for example, a lamp or a light emitting diode, and emits light of a wavelength that does not sensitize the resist on the substrate. The collimator lens 71 converts the light emitted from the light source 70 into parallel light with a substantially uniform cross-sectional light intensity distribution. The slit member 72 is composed of a pair of prisms bonded together so that the slanted surfaces face each other. is provided with a light shielding film. The optical system 73 is a telecentric optical system on both sides, and transmits a plurality of light beams (nine light beams in this embodiment) generated by passing through a plurality of openings in the slit member 72 onto the substrate via a mirror 74. make it incident.

In this embodiment, the projection system 17a is configured such that the angle φ at which each light beam is incident on the substrate 15 (the angle between the light beam and the optical axis of the projection optical system 14) is, for example, 70 degrees or more. . Further, as shown in FIG. 2, the projection system 17a forms an angle .theta. It is configured to make nine light beams enter the substrate 15 from different directions. By making the nine light beams obliquely enter the substrate 15 in this manner, the surface height of the substrate 15 can be measured independently at each of the plurality (nine) of measurement points 30 .

The light receiving system 17b can include, for example, a mirror 75, a light receiving optical system 76, a correction optical system 77, a photoelectric conversion section 78, and a processing section 79. The mirror 75 guides the nine light beams reflected by the substrate 15 to the light receiving optical system 76 . The light-receiving optical system 76 is a double-side telecentric optical system, and includes a diaphragm provided in common for the nine light beams. High-order diffracted light (noise light) generated due to the circuit pattern formed on the substrate is blocked by the diaphragm included in the light receiving optical system 76 . The correction optical system 77 has a plurality of (nine) lenses so as to correspond to the nine light beams. A hole image is formed respectively. The photoelectric conversion unit 78 includes a plurality of (nine) photoelectric conversion elements so as to correspond to the nine luminous fluxes. For example, a CCD line sensor, a CMOS line sensor, or the like is used as the photoelectric conversion element. The processing unit 79 also calculates the surface height of the substrate 15 at each measurement point 30 based on the output from the photoelectric conversion unit 78 (the position of each pinhole image on the light receiving surface).

By configuring the irradiation system 17a and the light receiving system 17b in this way, the measurement unit 17 can detect the position of each pinhole image on the light receiving surface of the photoelectric conversion unit 78 at each measurement point 30 (each measurement unit). can measure the height of the substrate surface. Then, the control unit 20 controls the driving of the substrate stage 16 based on the measurement result of the measurement unit 17, and adjusts the height of the substrate 15 so that the substrate surface is arranged at the target height (imaging plane). be able to. Here, in the light-receiving system 17b, inclination correction is performed so that each measurement point 30 on the substrate and the light-receiving surface of the photoelectric conversion unit 78 are conjugated with each other. Therefore, the position of each pinhole image on the light receiving surface of the photoelectric conversion unit 78 does not change depending on the local tilt of each measurement point 30 .

[Scanning exposure of shot area]
Scanning exposure of the shot area 15a of the substrate 15 in the exposure apparatus 100 described above will be described. FIG. 3 shows a shot region 15a to be scanned and exposed, an irradiation region 21 irradiated with exposure light from the projection optical system 14, and a plurality of measurement points at which surface height measurement (focus measurement) is performed by the measurement unit 17. 30 is a diagram showing a positional relationship with 30. FIG. In FIG. 3, the irradiation area 21 is a rectangular area surrounded by dashed lines. The measurement points 30a (30a ₁ to 30a ₃ ) are measurement points for focus measurement inside the irradiation area 21 . Measurement points 30b (30b ₁ to 30b ₃ ) and measurement points 30c (30c ₁ to 30c ₃ ) are measurement points (prefetch measurement points) for focus measurement prior to exposure in the irradiation area 21 . The measurement points 30b and 30c are arranged at positions separated from the measurement point 30a in the irradiation area 21 by a distance Lp in the scanning direction (±Y direction). In this embodiment, each of the measurement points 30a, 30b, and 30c is composed of three measurement points arranged in a direction (X direction) intersecting the scanning direction (Y direction). or four or more measurement points. Also, the measurement point 30a can be used to calibrate the measurement results at the measurement points 30b and 30c.

In the measurement unit 17 configured as described above, the measurement point used for focus measurement prior to exposure in the irradiation area 21 is switched according to the scanning direction (moving direction) of the substrate 15 . For example, when the substrate 15 is moved in the direction F to scan and expose the shot area 15a, the measurement point 30b is used. In this case, the control unit 20 drives the substrate stage 16 based on the measurement result at the measurement point 30 b so that the substrate surface within the irradiation area 21 is arranged on the imaging plane of the projection optical system 14 . Make 15 height adjustments. On the other hand, when the substrate 15 is moved in the direction R to scan and expose the shot area 15a, the measurement point 30c is used. In this case, the control unit 20 drives the substrate stage 16 based on the measurement result at the measurement point 30 b so that the substrate surface within the irradiation area 21 is arranged on the imaging plane of the projection optical system 14 . Make 15 height adjustments.

[Example of acquisition of conventional step distribution]
In a plurality of shot regions 15a on the substrate 15, a common pattern structure having a step distribution (for example, an uneven shape) may be formed by conventional semiconductor processes. In the scanning exposure in this case, if the height of the substrate 15 is frequently changed so as to follow the pattern structure based only on the measurement result of the measuring unit 17, the adjustment delay of the height of the substrate 15 may occur. That is, it may be difficult to accurately adjust the height of the substrate (also called focus leveling control) in scanning exposure. Therefore, in the exposure apparatus 100, the step difference distribution of the common pattern structure formed in each shot area is acquired in advance as a pattern offset, and based on the result of correcting the measurement result of the measurement unit 17 by the step difference distribution, Controls substrate height adjustment in scanning exposure.

An example of conventional processing for acquiring the step distribution of the pattern structure will be described below. FIG. 4(a) is a diagram showing an arrangement example of a plurality of shot regions 15a on a substrate, and it is assumed that a common pattern structure is formed in each of the plurality of shot regions 15a. Also, FIG. 4A shows the positions of sample shot regions 200 (sample regions) used to acquire the step distribution of the pattern structure. The sample shot areas 200 can be set by the user or by the controller 20 in a number and arrangement that can accurately acquire the step distribution of the pattern structure.

Here, in each sample shot area 200, a plurality of measurement target locations whose surface heights are to be measured by the measurement unit 17 can be set along the scanning direction (Y direction). In this embodiment, as shown in FIG. 4B, each sample shot area 200 has five measurement target points s1 to s5. Any one of the measurement points 30a to 30c may be used as the measurement point of the measurement unit 17 for measuring the surface height of each measurement target location, or two or more of the measurement points 30a to 30c may be used. may In the latter case, the average value of the values obtained at the two or more measurement points can be used as the measured value of the surface height of each measurement target location.

For example, while the substrate stage 16 scans the substrate 15 , the control unit 20 causes the measurement unit 17 to measure the surface height of each measurement target location in each sample shot region 200 . Thereby, as shown in FIG. 5A, the surface height distribution of each sample shot area 200 can be obtained. In the example shown in FIG. 5A, the surface height distribution of each of the five sample shot regions 200 (sam1 to sam5) is the surface height distribution obtained by the measurement unit 17 for each of the measurement target points s1 to s5. It is shown as a measured value.

Next, the control unit 20 obtains an approximate plane gt for all of the surface height measurement values obtained for each of the measurement target points s1 to s5 of the sample shot areas sam1 to sam5. Then, the difference between the approximate plane gt and the measured value is obtained for each of the measurement target points s1 to s5, and the average values of the differences in the sample shot areas sam1 to sam5 are obtained as the pattern offsets c1 to c5. The pattern offsets c1 to c5 obtained for each of the measurement target points s1 to s5 in this way are the distribution indicating the relative surface heights at the measurement target points s1 to s5, that is, the common pattern formed in each shot area. 4 shows the step distribution of the structure.

Here, the approximate plane gt is a plane substantially parallel to the shape component (for example, the surface shape of the substrate) of the substrate surface w1 when it is assumed that there is no pattern structure, and is located at the target height (the imaging plane of the projection optical system 14). ). That is, by moving (shifting) the approximate plane gt in the height direction (Z direction), the surface of the substrate placed on the imaging plane of the projection optical system 14 can be arbitrarily set. As an example, when the approximate plane gt is moved to the substrate surface w1, the height adjustment of the substrate can be controlled so that the substrate surface w1 is placed on the imaging plane of the projection optical system 14 in scanning exposure. It is also possible to change the position of the approximate plane gt by adding an arbitrary constant value to the pattern offsets c1 to c5.

FIG. 5(b) is a diagram showing pattern offsets c1 to c5 (that is, the step distribution of the pattern structure) obtained for each of the measurement target points s1 to s5. FIG. 5B shows pattern offsets c1 to c5 when the height position of the approximate plane gt is aligned with the substrate surface w1. During scanning exposure of each shot region 15a, the control unit 20 corrects the measurement result of the measurement unit 17 using a pattern offset according to the measurement position of the measurement unit 17 (measurement point 30b or 30c), and based on the result, to adjust the height of the substrate 15. Thereby, the height adjustment of the substrate 15 can be controlled by following the surface shape of the substrate 15 so that the substrate surface w1 is arranged on the imaging plane of the projection optical system 14 .

[Example of acquisition of step distribution according to the present embodiment]
In the exposure apparatus 100, it is disadvantageous in terms of throughput to acquire the step distribution of the pattern structure each time the substrate or lot is changed. Therefore, if the pattern structure of each shot area is the same even if the substrate or lot is changed, it is preferable to apply the step distribution obtained in the past. However, the substrate used to obtain the step distribution and the substrate to be exposed may be distorted due to the substrate itself or the state of being held by the substrate stage 16 (flatness of the substrate chuck). surface distortion) may differ from each other. Therefore, it may be difficult to appropriately determine whether or not the step distribution obtained in the past is applicable. Therefore, the exposure apparatus 100 of the present embodiment determines whether or not the step distribution acquired in the past can be applied in consideration of the distortion of the substrate surface.

First, the process of acquiring the step distribution of the pattern structure in this embodiment will be described. The processing of this embodiment is basically the same as the conventional processing described above, but differs in that the surface shape of the substrate is taken into consideration. Specifically, while the substrate stage 16 is scanning the substrate 15, the control unit 20 causes the measuring unit 17 to measure the surface height of each measurement target point in each of the sample shot areas sam11 to sam15. Thereby, as shown in FIG. 6A, the surface height distribution of each sample shot area sam11 to sam15 can be obtained. Here, the surface height distribution includes a component caused by the distortion of the substrate (that is, the shape component of the substrate surface w1).

As shown in FIG. 6(a), the control unit 20 calculates the approximate planes gt11 to gt15 for the measured values of the surface height obtained for each of the measurement target points s1 to s5 for each of the sample shot areas sam11 to sam15. Ask for Also, an average (averaged) approximate plane gt1 of the approximate planes gt11 to gt15 is obtained. Then, for each of the sample shot areas sam11 to sam15, the difference between the approximate plane gt1 and the measured value is obtained for each of the measurement target points s1 to s5, and the average value of the differences for each of the measurement target points s1 to s5 is calculated as the pattern offset c1 to c1. It is obtained as c5.

FIG. 6B is a diagram showing the pattern offsets c1 to c5 (step distribution ptn11 of the pattern structure) obtained for each of the measurement target points s1 to s5. The step distribution ptn11 of the pattern structure includes the shape component of the substrate surface w1 caused by the distortion of the substrate such as the substrate itself and the state of being held by the substrate stage 16 . It is known that the shape component of the substrate surface w1 is a low-frequency component (has a long period) compared to the pattern structure formed in each shot area. Therefore, in the present embodiment, the step distribution ptn11 of the pattern structure is subjected to spatial frequency filtering for removing components of a predetermined order or less (for example, first-order components). For example, an approximate plane is obtained for the step distribution ptn11 (pattern offsets c1 to c5) of the pattern structure, and the obtained approximate plane is removed from the step distribution ptn11 as the shape component (primary component gt1′) of the substrate surface w1. I do. Note that the first-order component gt1' may be the average approximate plane gt1 of the approximate planes gt11 to gt15. As a result, as shown in FIG. 6C, it is possible to obtain a step distribution ptn12 (hereinafter sometimes referred to as "correction distribution ptn12") of the pattern structure in which the component caused by the distortion of the substrate is reduced. . As the number of sample shot areas increases, the correction distribution ptn12 can be obtained with higher accuracy by reducing the influence of the shape component of the substrate surface w1.

Next, the process of determining whether or not the step distribution (correction distribution ptn12) of the pattern structure acquired in the past is applicable will be described. In this process, the step distribution of the pattern structure is acquired as a confirmation distribution (first distribution) using the substrate to be exposed, and the change amount of the confirmation distribution with respect to the previously acquired correction distribution ptn12 (second distribution) is (difference) is calculated. Then, when the amount of change is equal to or less than a threshold (determination threshold), it can be determined that the correction distribution ptn12 acquired in the past is applicable.

Acquisition of the distribution for confirmation can be performed using the same processing as acquisition of the distribution for correction ptn12. However, the number of sample shot areas 200 selected to obtain the confirmation distribution is preferably less than the number of sample shot areas 200 used to obtain the correction distribution ptn12 in terms of throughput. For example, the plurality of sample shot areas 200 for obtaining the correction distribution ptn12 are preferably selected as many and evenly as possible over the entire substrate 15, as shown in FIG. 7(a). As a result, the influence of the shape component of the substrate surface w1 can be reduced, and the step distribution of the pattern structure can be accurately obtained. On the other hand, the plurality of sample shot areas 200 for acquiring the confirmation distribution are selected from a relatively small number from the viewpoint of throughput so that the surface height distribution can be continuously measured by the measurement unit 17. preferably. As an example, a plurality of sample shot areas 200 for obtaining a confirmation distribution may be arranged in the center of the substrate and/or adjacent to each other on the substrate, as shown in FIG. 7(b). I hope it matches. An example in which three sample shot areas sam21 to sam23 are selected as the plurality of sample shot areas 200 for acquiring the confirmation distribution will be described below.

While the substrate stage 16 scans the substrate 15, the control unit 20 causes the measuring unit 17 to measure the surface height of each of the measurement target points s1 to s5 of the sample shot areas sam21 to sam23. Thereby, as shown in FIG. 8A, the surface height distribution of each sample shot area sam21 to sam23 can be obtained. The control unit 20 also obtains approximate planes gt21 to gt23 for each of the sample shot areas sam21 to sam23, and calculates an average (averaged) approximate plane gt2. Then, average values of differences between the approximate plane gt2 and the measured values are obtained as pattern offsets c1' to c5' for each of the measurement target points s1 to s5. Thereby, the step distribution ptn21 of the pattern structure can be obtained.

FIG. 8B is a diagram showing pattern offsets c1' to c5' (step distribution ptn21 of the pattern structure) obtained for each of the measurement target points s1 to s5. Ideally, the step distribution ptn21 shown in FIG. 8B has the same result (same shape) as the step distribution ptn11 shown in FIG. 6B. However, the step distribution ptn11 shown in FIG. 6B and the step distribution ptn21 shown in FIG. 8B differ from each other due to the influence of the shape component of the substrate surface. It is not appropriate to determine applicability. Therefore, in the present embodiment, the step distribution ptn21 shown in FIG. 8B is subjected to spatial frequency filtering for removing components of a predetermined order or less (for example, primary components). Then, the distribution obtained by the filtering process is compared with the past correction distribution ptn12 (FIG. 6(c)) to determine whether or not the past correction distribution ptn12 is applicable.

For example, an approximate plane is obtained for the step distribution ptn21 (pattern offsets c1′ to c5′) of the pattern structure, and the obtained approximate plane is removed from the step distribution ptn21 as the shape component (primary component gt2′) of the substrate surface w2. Filter. Note that the first-order component gt2' may be the average approximate plane gt2 of the approximate planes gt21 to gt23. As a result, as shown in FIG. 8C, it is possible to obtain a step distribution ptn22 (hereinafter sometimes referred to as "confirmation distribution ptn22") of the pattern structure in which the shape component of the substrate surface w2 is reduced. The control unit 20 obtains the amount of change in the confirmation distribution ptn22 (FIG. 8(c)) with respect to the correction distribution ptn12 (FIG. 6(c)). It can be determined that the correction distribution ptn12 is applicable to the substrate to be exposed. That is, in this case, the control unit 20 controls the scanning exposure of each shot area while adjusting the height of the substrate based on the result of correcting the measurement result of the measuring unit 17 using the correction distribution ptn12 acquired in the past. be able to.

As described above, the exposure apparatus according to the present embodiment performs spatial frequency filtering on the surface height distribution measured for the substrate to be exposed, thereby obtaining the step distribution of the pattern structure from the confirmation distribution (first distribution). ). Then, when the amount of change in the confirmation distribution with respect to the correction distribution (second distribution) acquired in the past is equal to or less than the threshold, the correction distribution acquired in the past is applied. Accordingly, it is possible to appropriately determine whether or not the step distribution acquired in the past is applicable, taking into consideration the distortion of the substrate surface.

<Second embodiment>
A second embodiment according to the present invention will be described. In this embodiment, an example of correcting the correction distribution ptn12 based on the amount of change (difference) in the confirmation distribution with respect to the correction distribution ptn12 will be described. It should be noted that the present embodiment basically succeeds the first embodiment unless otherwise specified.

Acquisition of the confirmation distribution in this embodiment can be performed using the same processing as the confirmation distribution ptn22 described in the first embodiment. Specifically, while the substrate stage 16 is scanning the substrate 15, the control unit 20 causes the measurement unit 17 to measure the surface height of each of the measurement target points s1 to s5 of the sample shot areas sam31 to sam33. Thereby, as shown in FIG. 9A, the surface height distribution of each sample shot area sam31 to sam33 can be obtained. The control unit 20 also obtains approximate planes gt31 to gt33 for each of the sample shot areas sam31 to sam33, and obtains an average (averaged) approximate plane gt3. Then, the average value of the differences between the approximate plane gt3 and the measured values is obtained for each of the measurement target points s1 to s5. Thereby, the step distribution ptn31 (FIG. 9B) of the pattern structure can be obtained. Then, the control unit 20 performs spatial frequency filtering on the step distribution ptn31 shown in FIG. 9B. Spatial filtering is, for example, a process of obtaining an approximate plane for the step distribution ptn31 of the pattern structure and removing the obtained approximate plane from the step distribution ptn31 as a shape component (primary component gt3') of the substrate surface w3. As a result, it is possible to obtain the pattern structure step distribution (confirmation distribution) ptn32 in which the shape distribution of the substrate surface is reduced.

FIG. 10 is a diagram showing a method of correcting the correction distribution ptn12 shown in FIG. 6(c). The control unit 20 obtains the change amount ptn4 of the confirmation distribution ptn32 with respect to the correction distribution ptn12, and if the change amount ptn4 is larger than the threshold, corrects (corrects) the previously acquired correction distribution ptn12 with the change amount ptn4. )do. As a result, the correction distribution ptn5 after correction can be obtained. The control unit 20 can adjust the height of the substrate with higher accuracy by using the result of correcting the measurement result of the measuring unit 17 using the corrected correction distribution ptn5 in the scanning exposure of each shot area.

In this embodiment, the correction distribution ptn12 is modified when the variation ptn4 exceeds the threshold. You may In this case, it is possible to more sensitively correct changes in pattern shape between substrates and lots. Further, when correcting the correction distribution ptn12 acquired in the past, the amount of change ptn4 multiplied by a predetermined gain may be used. As a result, when there is an abnormal point in some sample shot areas and the amount of change ptn4 is affected by it, the influence can be reduced. In this case, if the change amount ptn4 is larger than the threshold, the step distribution of the pattern structure can be newly obtained by applying the processing for acquiring the correction distribution ptn12 described in the first embodiment.

Also, a plurality of thresholds may be provided. For example, assume a case where a first threshold and a second threshold larger than the first threshold are provided. In this case, if the change amount ptn4 is equal to or less than the first threshold, the correction distribution ptn12 acquired in the past is applied as it is. On the other hand, if the change amount ptn4 is greater than the first threshold and equal to or less than the second threshold, the correction distribution ptn12 acquired in the past is corrected with the change amount ptn4, and the corrected correction distribution ptn5 is applied. If the change amount ptn4 is greater than the second threshold value, the process for acquiring the correction distribution ptn12 described in the first embodiment is applied to newly obtain the step distribution of the pattern structure. By providing a plurality of thresholds in this way, it is possible to change the processing corresponding to various risks. For example, when the threshold is greatly exceeded, it is highly possible that there is an abnormality in the correction distribution ptn12 acquired in the past. Therefore, rather than correcting and applying the correction distribution ptn12 that has been obtained in the past, obtaining a new distribution for correction can more accurately adjust the height of the substrate in scanning exposure.

<Third Embodiment>
A third embodiment according to the present invention will be described. In this embodiment, an example of the flow of scanning exposure processing for each shot area described in the first embodiment and/or the second embodiment will be described with reference to FIG. FIG. 11 is a flowchart showing an example of the flow of scanning exposure processing. Each step of the flowchart can be controlled by the control unit 20 .

In S<b>1 , the controller 20 uses a transport hand (not shown) to load the substrate 15 onto the substrate stage 16 and causes the substrate stage 16 to hold the substrate 15 . In S2, the control unit 20 performs pre-measurement and correction for the global alignment process of S6, which will be described later (pre-alignment process). Specifically, the control unit 20 uses a low-magnification alignment scope (not shown) to adjust the position, rotation, etc. of the substrate 15 so that the marks on the substrate 15 fit within the field of view of a high-magnification alignment scope (not shown) used for global alignment. Measure and correct the amount of deviation. In S3, the control unit 20 measures the surface heights of the substrate 15 at a plurality of locations using the measurement unit 17, for example, and calculates and corrects the overall tilt of the substrate 15 (global tilt step). FIG. 12 is a plan view of the substrate 15 showing, as an example, a portion (shot region 201) whose surface height is to be measured.

S4-1 to S4-6 are steps for determining whether or not the correction distribution obtained in the past is applicable, and the processing described above in the first embodiment and/or the second embodiment can be performed. In this embodiment, an example in which a plurality of thresholds (first threshold and second threshold) are provided will be described. In addition, the second threshold can be set to a value larger than the first threshold.

In S4-1, the control unit 20 determines whether or not there is a correction distribution acquired in the past. If there is no correction distribution acquired in the past, proceed to S4-2, otherwise proceed to S4-3. In S4-2, the control unit 20 causes the measurement unit 17 to measure the surface height distribution of the first number of sample shot regions 200, and performs spatial frequency filtering on the step distribution of the pattern structure obtained thereby. By doing so, a new distribution for correction is obtained. On the other hand, in S4-3, the control unit 20 causes the measurement unit 17 to measure the surface height distribution of the second number of sample shot areas 200 smaller than the first number, and the step distribution of the pattern structure obtained thereby. A verification distribution is obtained by performing spatial frequency filtering on .

In S4-4, it is determined whether or not the amount of change in the confirmation distribution with respect to the correction distribution obtained in the past is equal to or less than the first threshold. If the amount of change is equal to or less than the first threshold, the process proceeds to S4-5. In S4-5, the control unit 20 applies the correction distribution obtained in the past as it is as the correction distribution used for correcting the measurement result of the measurement unit 17 in the scanning exposure. On the other hand, if the amount of change is greater than the first threshold, the process proceeds to S4-6.

In S4-6, it is determined whether or not the amount of change in the confirmation distribution with respect to the correction distribution obtained in the past is equal to or less than the second threshold. If the amount of change is equal to or less than the second threshold, the process proceeds to S4-7. In S4-7, the control unit 20 selects the correction distribution obtained by correcting the correction distribution obtained in the past with the change amount as the correction distribution used for correcting the measurement result of the measurement unit 17 in the scanning exposure. apply. On the other hand, if the amount of change is greater than the second threshold value, the process proceeds to S4-2 to obtain a new distribution for correction.

In S5, the control unit 20 calculates and corrects correction values for the inclination of the projection lens in the projection optical system 14 and the field curvature (projection lens correction step). A light amount sensor and reference marks provided on the substrate stage 16 and a reference plate provided on the mask stage 13 can be used to calculate the correction value. Specifically, the control unit 20 causes the light amount sensor to measure the light amount change of the exposure light when the substrate stage 16 is scanned in the XYZ axial directions. Then, based on the amount of change in the amount of light output from the light amount sensor, the amount of deviation of the reference mark from the substrate plate is obtained, and a correction value for correcting the amount of deviation is calculated.

In S6, a high-magnification alignment scope (not shown) is used to measure the alignment marks on the substrate, and the amount of misalignment of the entire substrate (including the amount of rotational misalignment) and the amount of misalignment common to each shot area are calculated and corrected. (global alignment step). Here, in order to measure the alignment mark with high accuracy, the contrast of the alignment mark must be at the best contrast position (height). A measurement unit 17 and an alignment scope can be used to measure this best contrast position. Specifically, the control unit 20 moves the substrate stage 16 to a predetermined height (Z direction), causes the alignment scope to measure the contrast, and causes the measurement unit 17 to measure the surface height of the substrate 15. Repeat the process several times. At this time, the control unit 20 associates and stores the measurement result of the surface height of the substrate 15 and the measurement result of the contrast corresponding to each surface height. Then, the control unit 20 obtains the height of the surface with the highest contrast based on the obtained measurement results of a plurality of contrasts, and determines the best contrast position (height).

In S7, the control unit 20 performs scanning exposure of each shot area. In the scanning exposure according to the present embodiment, the control unit 20 causes the measuring unit 17 to measure the surface height of the shot area to be exposed, and adjusts the height of the substrate based on the result of correcting the measurement result using the correction distribution. Make sequential adjustments (perform focus leveling control). In S8, the controller 20 ends the holding of the substrate 15 by the substrate stage 16 after the scanning exposure of all the shot areas on the substrate 15 is completed, and removes the substrate 15 from the substrate stage 16 using a transport hand (not shown). Carry out. Thus, a series of scanning exposure processes for one substrate 15 is completed.

<Embodiment of method for manufacturing article>
The method for manufacturing an article according to the embodiment of the present invention is suitable for manufacturing an article such as a microdevice such as a semiconductor device or an element having a fine structure. The method for manufacturing an article according to the present embodiment includes a step of forming a latent image pattern on a photosensitive agent applied to a substrate using the exposure apparatus (the step of exposing the substrate), and a step of forming the latent image pattern in this step. and developing (processing) the substrate. In addition, such manufacturing methods include other well-known steps (oxidation, deposition, deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The article manufacturing method of the present embodiment is advantageous in at least one of article performance, quality, productivity, and production cost compared to conventional methods.

The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the claims are appended to make public the scope of the invention.

11: illumination optical system, 12: mask, 13: mask stage, 14: projection optical system, 15: substrate, 16: substrate stage, 17: measurement section, 20: control section, 100: exposure apparatus

Claims (9)

An exposure apparatus for exposing a plurality of regions on a substrate, each region having a common pattern structure,
a measurement unit that measures the surface height distribution of each region;
a control unit that controls the exposure of each region,
The control unit
step distribution of the pattern structure by removing components of a predetermined order or less from the surface height distribution measured by the measuring unit for a plurality of sample regions selected from the plurality of regions; as the first distribution,
When the amount of change in the first distribution with respect to the second distribution, which is the step distribution of the pattern structure obtained in the past, is equal to or less than a threshold, the substrate is measured based on the second distribution and the measurement result of the measurement unit. An exposure apparatus characterized by controlling exposure of each area while adjusting height. The number of the plurality of sample areas selected to obtain the first distribution is less than the number of sample areas whose surface height distribution was measured by the measurement unit to obtain the second distribution. 2. The exposure apparatus according to claim 1, wherein: 3. An exposure apparatus according to claim 1, wherein said plurality of sample areas selected to obtain said first distribution are adjacent to each other on said substrate. 4. An exposure apparatus according to any one of claims 1 to 3, wherein said plurality of sample areas selected to obtain said first distribution are arranged in a central portion of said substrate. The control unit removes, from the surface height distribution of the substrate measured by the measurement unit, a component caused by distortion of the substrate as a component of the predetermined order or less, thereby removing the first distribution 5. The exposure apparatus according to any one of claims 1 to 4, wherein . The control unit controls the exposure of each region while adjusting the height of the substrate based on the distribution obtained by correcting the second distribution by the amount of change and the measurement result of the measurement unit. 6. The exposure apparatus according to any one of claims 1 to 5, characterized by: The control unit
if the amount of change is greater than the threshold, apply the process used to obtain the second distribution to obtain a new step distribution of the pattern structure;
7. The method of claim 1, wherein the exposure of each region is controlled while adjusting the height of the substrate based on the newly obtained step distribution of the pattern structure and the measurement result of the measurement unit. The exposure apparatus according to any one of items 1 and 2. an exposure step of exposing a substrate using the exposure apparatus according to any one of claims 1 to 7;
and a processing step of processing the substrate exposed in the exposure step,
A method for manufacturing an article, comprising manufacturing an article from the substrate processed in the processing step. An exposure method for exposing a plurality of regions on a substrate, each region having a common pattern structure,
a measurement step of measuring a surface height distribution for a plurality of sample regions selected from the plurality of regions;
an acquiring step of acquiring the step distribution of the pattern structure as a first distribution by performing a process of removing components of a predetermined order or less from the surface height distribution measured in the measuring step;
When the variation of the first distribution with respect to the second distribution, which is the step distribution of the pattern structure obtained in the past, is equal to or less than a threshold value, the result of correcting the measurement result of the surface height distribution of each region by the second distribution. a control step of controlling the exposure of each region while adjusting the height of the substrate based on;
An exposure method comprising:

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