JP2018197801A - Image surface measurement device, image surface measurement method, exposure device, exposure method, and device production method - Google Patents

Abstract

To provide an image surface measurement device that shortens the time required for measuring the position of an image surface.SOLUTION: An image surface measurement device 7 measures the position of an image surface of a projection optical system 3 that projects an image of a desired pattern onto the image surface by exposure light EL. The device has: an input interface 71 that receives input of first information on the state of an image formed by the exposure light through the projection optical system and second information on the properties of the projection optical system; and a controller 72 that calculates the position of the image surface using the first and second information.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image plane measuring apparatus and an image plane measuring method for measuring the position of an image plane of a projection optical system, an exposure apparatus and an exposure method for exposing an object using the image plane measuring apparatus or the image plane measuring method, and The present invention relates to a technical field of a device manufacturing method for manufacturing a device using this exposure method.

  The exposure apparatus transfers the desired pattern onto the object by projecting the exposure light through the desired pattern onto the object with the projection optical system. In such an exposure apparatus, the position of the image plane of the projection optical system is measured. It is desired to reduce the time required for measuring the position of the image plane.

US Patent Application Publication No. 2007/296945

  According to the first aspect, there is provided an image plane measuring apparatus for measuring a position of the image plane of a projection optical system that projects an image of a desired pattern onto an image plane with exposure light, the exposure via the projection optical system. The position of the image plane is calculated using an input interface to which first information relating to a state of an image formed by light and second information relating to characteristics of the projection optical system are inputted, and the first and second information. An image plane measuring device including a controller is provided.

  According to the second aspect, there is provided an image plane measuring device that measures the position of the image plane of the projection optical system that projects an image of a desired pattern onto the image plane by exposure light, and the first plane is the first plane under the first illumination condition. An input interface for inputting first information relating to a state of an image formed by the projection optical system and second information relating to characteristics of the projection optical system under the first illumination condition; An image plane measuring device including a controller that calculates the position of the image plane using the two information is provided.

  According to a third aspect, there is provided an image plane measurement method for measuring a position of the image plane of a projection optical system that projects an image of a desired pattern onto an image plane with exposure light, the exposure via the projection optical system. Obtaining first information relating to a state of an image formed by light and second information relating to characteristics of the projection optical system; calculating a position of the image plane using the first and second information; Is provided.

  According to a fourth aspect, there is provided an image plane measurement method for measuring a position of the image plane of a projection optical system that projects an image of a desired pattern onto an image plane with exposure light, and the method is performed under a first illumination condition. Acquiring first information relating to a state of an image formed by the projection optical system and second information relating to characteristics of the projection optical system under the first illumination condition; and the first and second information. And calculating the position of the image plane.

  According to the 5th aspect, an exposure apparatus provided with the image surface measuring device in a 1st or 2nd aspect is provided.

  According to the 6th aspect, the exposure apparatus which exposes a board | substrate using the measurement result of the image surface measuring method in a 3rd or 4th aspect is provided.

  According to the 7th aspect, the exposure method which exposes a board | substrate using the image surface measuring device in the 1st or 2nd aspect is provided.

  According to the 8th aspect, the exposure method which exposes a board | substrate using the measurement result of the image surface measuring method in the 3rd or 4th aspect is provided.

  According to the ninth aspect, by using the exposure method according to the seventh or eighth aspect, the substrate coated with the photosensitive material is exposed, a desired mask pattern is transferred to the substrate, and the exposed photosensitive material. Is developed to form an exposure pattern layer corresponding to the desired mask pattern, and a device manufacturing method is provided for processing the substrate through the exposure pattern layer.

  According to the 10th aspect, the computer program which makes a computer perform the image plane measuring method in a 3rd or 4th aspect is provided.

FIG. 1 is a block diagram showing the configuration of the exposure apparatus of the present embodiment. FIG. 2 is a flowchart showing the flow of the image plane measurement operation performed by the exposure apparatus of this embodiment. FIG. 3 is a flowchart showing a flow of processing for acquiring image information in the image plane measurement operation shown in FIG. FIG. 4 is a plan view showing a pattern surface of a mask for image plane measurement.

FIG. 5 is a flowchart showing a flow of processing for acquiring aberration information in the image plane measurement operation shown in FIG. FIG. 6 is a flowchart showing a flow of processing for calculating the position of the image plane in the image plane measurement operation shown in FIG. FIG. 7 is a flowchart showing the flow of the device manufacturing method.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments described below.
(1) Configuration of Exposure Apparatus EX First, an example of the configuration of the exposure apparatus EX of the present embodiment will be described with reference to FIG. FIG. 1 is a schematic view showing a cross section (partly a processing block) of the exposure apparatus EX of the present embodiment. In the following description, the positional relationship of the components constituting the exposure apparatus 1 will be described using an XYZ orthogonal coordinate system defined by the X axis, the Y axis, and the Z axis orthogonal to each other. For convenience of explanation, each of the X-axis direction and the Y-axis direction is a horizontal direction (that is, a predetermined direction in the horizontal plane), and the Z-axis direction is a vertical direction (that is, a direction orthogonal to the horizontal plane, and substantially up and down. Direction). Further, the rotation directions around the X axis, the Y axis, and the Z axis (in other words, the tilt direction) are referred to as a θX direction, a θY direction, and a θZ direction, respectively.

  The exposure apparatus 1 exposes an object. In the following, it is assumed that the object is a substrate 41 such as a semiconductor substrate coated with a resist. In this case, the exposure apparatus 1 exposes the substrate 41 to transfer a device pattern (for example, a semiconductor element pattern) to the substrate 41. That is, the exposure apparatus 1 is an exposure apparatus for manufacturing a device such as a semiconductor device. However, as will be described later, the exposure apparatus 1 may be an arbitrary exposure apparatus that exposes an arbitrary object or irradiates light on an arbitrary object.

  In order to transfer the device pattern to the substrate 41, the exposure apparatus EX includes a mask stage 1, an illumination system 2, a projection optical system 3, a substrate stage 4, and an image plane measuring system 5, as shown in FIG. A wavefront measuring system 6 and a control device 7 are provided. For convenience of explanation, FIG. 1 shows the mask stage 1, the illumination system 2, the projection optical system 3, the substrate stage 4, the image plane measurement system 5, and the wavefront measurement system 6 in a sectional view, while the control device 7. Is not shown in the block diagram.

  The mask stage 1 holds the mask 11 on which a mask pattern corresponding to the device pattern transferred to the substrate 41 is formed. The mask stage 1 is movable along a plane (for example, an XY plane) including an illumination area irradiated with the exposure light EL emitted from the illumination system 2 while holding the mask 11. For example, the mask stage 1 moves by the operation of a mask drive system including a motor. The mask stage 1 is movable along the X-axis direction, the Y-axis direction, the Z-axis direction, and at least one of the θX direction, the θY direction, and the θZ direction by the operation of the mask drive system.

The illumination system 2 emits exposure light EL. The exposure light EL may be, for example, a bright line (for example, g line, h line, or i line) emitted from a mercury lamp. The exposure light EL may be far ultraviolet light (DUV light: Deep Ultra Violet light) such as KrF excimer laser light (wavelength 248 nm), for example. The exposure light EL may be vacuum ultraviolet light (VUV light: Vacuum Ultra Violet light) such as ArF excimer laser light (wavelength 193 nm) or F ₂ laser light (wavelength 157 nm), for example. The exposure light EL emitted from the illumination system 2 is applied to a part of the mask 11.

  The projection optical system 3 projects the exposure light EL transmitted through the mask 11 (that is, the image of the mask pattern formed on the mask 11) onto the substrate 41. The projection optical system 3 is a projection optical system including a refractive optical element, but may be a projection optical system including a reflective optical element in addition to or instead of the refractive optical element. The projection optical system 3 is a reduction system, but may be an equal magnification system or an enlargement system. The projection optical system 3 may project the mask pattern image as an inverted image, or may project the mask pattern image as an erect image.

  The substrate stage 4 holds the substrate 41 by accommodating the substrate 41 in a recess formed on the upper surface of the substrate stage 4. The substrate stage 4 is movable along a plane (for example, an XY plane) including a projection area onto which the exposure light EL is projected by the projection optical system 3 while holding the substrate 41. For example, the substrate stage 4 moves by the operation of a substrate driving system including a motor. The substrate stage 4 is movable along at least one of the X-axis direction, the Y-axis direction, the Z-axis direction, and the θX direction, the θY direction, and the θZ direction by the operation of the substrate driving system.

  The image measurement system 5 is a measurement device that captures an image of the upper surface of the substrate 41 (that is, the upper surface of the substrate 41 serving as a projection surface onto which the exposure light EL is projected). For example, the image measurement system 5 includes a light source that irradiates the substrate 41 with illumination light, and an imaging element that includes an imaging surface on which an image of reflected light from the substrate 41 is formed. The image signal acquired by the image measurement system 5 is output from the image measurement system 5 to the control device 7. The image measurement system 5 is disposed on the side surface of the projection optical system 3. For this reason, the image measurement system 5 images the substrate 41 without using the projection optical system 3. However, the image measurement system 5 may image the substrate 41 via the projection optical system 3.

  The wavefront measuring system 6 is a measuring device that measures the wavefront of the exposure light EL that has passed through the projection optical system 3. For example, the wavefront measuring system 6 includes a light receiving element (typically, an imaging element) that can receive the exposure light EL that has passed through the projection optical system 3. The wavefront measuring system 6 may be, for example, a measuring device capable of measuring a wavefront using an interference measurement method. The wavefront measuring system 6 may be a measuring device capable of measuring a wavefront using, for example, a Shack-Hartmann measurement method. Such a wavefront measuring system 6 is disclosed in, for example, US Pat. No. 7,667,829. The wavefront measuring system 6 may be a measuring device that can measure the wavefront using, for example, other existing measurement methods. For this reason, detailed description of the wavefront measuring system 6 itself is omitted. The wavefront measuring system 6 is disposed on the substrate stage 4. In particular, the wavefront measuring system 6 is disposed outside the concave portion on the upper surface of the substrate stage 4 in which the substrate 41 is accommodated. In this case, the height of the imaging surface of the imaging device included in the wavefront measuring system 6 (that is, the position in the Z-axis direction) is the same as the height of the upper surface of the substrate 41.

  The control device 7 controls the overall operation of the exposure apparatus 1. The control device 7 outputs a control command for operating each operation block included in the exposure apparatus 1 to each operation block. Each operation block operates according to a control command. For example, the control device 7 controls the movement of the mask stage 1 and the substrate stage 4 so that a desired device pattern is transferred to a desired position in a desired shot area on the substrate 41.

  In the present embodiment, in particular, the control device 7 projects the projection optics based on the input interface 71 to which the measurement result of the image measurement system 5 and the measurement result of the wavefront measurement system 6 are input, and the measurement result input to the input interface 71. And an arithmetic processing unit 72 that calculates (that is, measures) the position of the image plane of the system 3 (in particular, the position of the projection optical system 3 in the optical axis direction). The arithmetic processing unit 72 is, for example, a processing device such as a CPU (Central Processing Unit) or a processing block that is logically realized in such a processing device. The arithmetic processing unit 72 calculates the position of the image plane of the projection optical system 3 by executing a computer program stored in a memory or the like (not shown) or input via the input interface 71.

  In particular, the arithmetic processing unit 72 calculates the position of the image plane on which the projection optical system 3 forms (that is, projects) an image of a desired mask pattern under desired illumination conditions. Hereinafter, the image plane measurement operation for calculating the position of the image plane will be further described. Since the desired mask pattern is a mask pattern that is a target for measuring the position of the image plane, in the following description, it is appropriately referred to as a “measurement target pattern”. Similarly, since the desired illumination condition is an illumination condition for measuring the position of the image plane, in the following description, it is appropriately referred to as “measurement object illumination condition”.

(2) Image plane detection operation
(2-1) Overall Flow of Image Plane Detection Operation First, the overall flow of the image plane measurement operation will be described with reference to FIG. FIG. 2 is a flowchart showing the overall flow of the image plane measurement operation.

  As shown in FIG. 2, first, the control device 7 acquires image information related to the state of an image formed by the exposure light EL via the projection optical system 3 based on the measurement result of the image measurement system 5 (step). S1). In particular, in step S1, the control device 7 acquires image information related to the state of an image of a special mask pattern for image plane measurement. The mask pattern for image plane measurement (hereinafter referred to as “test pattern” as appropriate) is different from the measurement target pattern. That is, the control device 7 does not have to acquire image information regarding the state of the image of the measurement target pattern. In the present embodiment, the control device 7 acquires, for example, information regarding the position of the image plane on which the image is formed as the image information regarding the state of the image. That is, the control device 7 acquires information regarding the position of the image plane on which the projection optical system 3 forms the test pattern image. 2 will be described in detail later with reference to FIG.

  After or before the process of step S1, the control device 7 acquires aberration information related to the wavefront aberration of the projection optical system 3 based on the measurement result of the wavefront measurement system 6 (step S2). 2 will be described in more detail later with reference to FIG.

  Thereafter, the control device 7 determines the image plane on which the projection optical system 3 forms an image of the measurement target pattern under the measurement target illumination conditions based on the image information acquired in step S1 and the aberration information acquired in step S2. The position is calculated (step S3). In other words, the control device 7 calculates the position of the image plane on which the image of the measurement target pattern is formed by the exposure light EL emitted under the measurement target illumination conditions. That is, in the present embodiment, the exposure apparatus EX does not actually measure the image of the measurement target pattern formed by the projection optical system 3 under the measurement target illumination condition, and does not actually measure the projection optical under the measurement target illumination condition. The position of the image plane on which the system 3 forms an image of the measurement target pattern can be calculated. The process in step S3 in FIG. 2 will be described in more detail later with reference to FIG.

(2-2) Processing for Acquiring Image Information Next, the flow of processing for acquiring image information in step S2 of FIG. 2 will be described with reference to FIG. FIG. 3 is a flowchart showing a flow of processing for acquiring image information in step S2 of FIG.

  As shown in FIG. 3, first, a mask 11 for image plane measurement (hereinafter referred to as “test mask 11a”) on which a test pattern is formed is loaded on the mask stage 1 (step S11). The test mask 11a is a phase shift mask. In particular, the test mask 11a is a phase shift mask that can be used to evaluate the focus position of the projection optical system 3 using a PSFM (Phase Shift Focus Monitor) method. As an example of such a test mask 11a, for example, a mask described in US Patent Application Publication No. 2011/1212389 can be cited. Specifically, as shown in FIG. 4, on the pattern surface of the test mask 11a, a plurality of measurement points P (i,) arranged in a matrix of I rows in the X-axis direction and J columns in the Y-axis direction. j) is set. Note that i is an integer of 1 to I, and j is an integer of 1 to J. However, a single measurement point P may be set on the pattern surface of the test mask 11a. At each measurement point P (i, j), there is a light shielding portion that does not allow the exposure light EL to pass, a passage portion that allows the exposure light EL to pass, and a phase shift portion that allows the exposure light EL to pass after being shifted in phase. A combined unit pattern is formed. Therefore, the test pattern formed on the test mask 11a is composed of a plurality of unit patterns arranged in a matrix. The unit pattern may be the same as the pattern described in US Patent Application Publication No. 2011/1212389, and thus detailed description thereof is omitted.

  After, before or in parallel with the process of step S11, the substrate 41 (in particular, the substrate 41 that has not been exposed by the exposure light EL) is loaded onto the substrate stage 1 (step S12).

  After that, the illumination condition of the illumination system 2 is set to the test illumination condition to be used for acquiring image information (that is, for exposing the substrate 41 with the exposure light EL through the test mask 11a) (step). S13). The illumination condition includes, for example, a light amount distribution at the exit pupil of the illumination system 2, which can be referred to as an illumination shape. In this case, the illumination condition is set to, for example, one of large σ illumination for normal illumination, small σ illumination with relatively small σ value, annular illumination, and modified illumination (for example, quadrupole illumination). May be.

  The test illumination condition may be the same as the measurement target illumination condition. In this case, when the measurement target illumination condition is large σ illumination, the test illumination condition is also large σ illumination. Alternatively, the test illumination conditions may be different from the measurement target illumination conditions that are targets for measuring the position of the image plane. In this case, when the measurement target illumination condition is large σ illumination, the test illumination condition is an illumination condition other than the large σ illumination (for example, small σ illumination, annular illumination, or modified illumination).

  Thereafter, the illumination system 2 emits the exposure light EL corresponding to the test illumination condition (step S13). As a result, the exposure light EL through the test pattern is projected onto the substrate 41 by the projection optical system 3 under the test illumination conditions (step S13). Specifically, each of a plurality of shot areas set on the substrate 41 is exposed by the exposure light EL through the test pattern. Therefore, a test pattern is transferred to each shot area.

  Thereafter, the substrate 41 to which the test pattern is transferred is unloaded from the substrate stage 4 (step S14). The unloaded substrate 41 is developed by the coater / developer (step S15). As a result, a resist image (that is, a resist pattern) corresponding to the test pattern is formed on the substrate 41.

  Thereafter, the developed substrate 41 is loaded again onto the substrate stage 4 (step S16). Thereafter, the image measurement system 5 captures a resist image (step S17). In particular, the image measurement system 5 captures a resist image at the measurement point Q (i, j) in each shot area corresponding to the measurement point P (i, j) on the test mask 11a. For this reason, the substrate stage 4 moves relative to the image measurement system 5 so that the image measurement system 5 can capture a resist image at the measurement point Q (i, j) in each shot region. However, the image measurement system 5 may capture a resist image at a desired position on the substrate 41.

  Thereafter, the measurement result (that is, the imaging data) of the image measurement system 5 is input as image information to the arithmetic processing unit 72 via the input interface 71 (step S18).

(2-3) Processing for Acquiring Aberration Information Next, the flow of processing for acquiring aberration information in step S3 in FIG. 2 will be described with reference to FIG. FIG. 5 is a flowchart showing the flow of processing for acquiring aberration information in step S3 of FIG.

  As shown in FIG. 5, the wavefront measuring system 6 measures the wavefront of the exposure light EL that has passed through the projection optical system 3 (step S21). In particular, the wavefront measurement system 6 measures the wavefront of the exposure light EL at each measurement point R (i, j) corresponding to each measurement point Q (i, j) at which a resist image is captured when acquiring image information. To do. That is, the wavefront measuring system 6 measures the wavefront of the exposure light EL at each measurement point R (i, j) whose relative position with respect to the projection optical system 3 coincides with each measurement point Q (i, j). For this reason, the substrate stage 4 moves together with the wavefront measurement system 6 so that the wavefront measurement system 6 can measure the wavefront at each measurement point R (i, j). For example, the substrate stage 4 moves together with the wavefront measurement system 6 so that the imaging surface of the wavefront measurement system 6 is positioned at each measurement point R (i, j). As a result, the position in the XY plane of the image obtained by the image measurement system 5 capturing a resist image at each measurement point Q (i, j) is determined by the wavefront measurement system 6 at each measurement point R (i, j). The position of the image obtained by imaging the wavefront is the same as the position in the XY plane.

  As an example, a wavefront measurement method in the case where the wavefront measurement system 6 is a measurement device that can measure a wavefront using an interference measurement method will be described. In this case, a mask 11 for wavefront measurement (hereinafter referred to as “test mask 11b”) is loaded on the mask stage 1. For example, a plurality of pinholes regularly arranged are formed on the pattern surface of the test mask 11b. Further, the substrate stage 4 is moved so that the wavefront measuring system 6 (particularly, its imaging device) is located in the projection area where the exposure light EL is projected via the projection optical system 3. Then, the illumination system 2 emits exposure light EL. At this time, the illumination system 2 emits the exposure light EL under the test illumination conditions used when acquiring the image information. As a result, the exposure light EL that has passed through the test mask 11 b (particularly, pinhole) and the projection optical system 3 enters the wavefront measurement system 6. In addition to the above-described image sensor, the wavefront measuring system 6 using the interference measurement method includes a diffraction grating in which a two-dimensional grating pattern is formed between the projection optical system 3 and the image sensor. The exposure light EL from the projection optical system 3 enters the diffraction grating. As a result, a plurality of diffracted lights are emitted from the diffraction grating. The plurality of diffracted lights interfere with each other to form interference light. The imaging device images the interference fringes formed by the interference light. Accordingly, the image sensor substantially detects the intensity distribution of the interference light as an image. A measurement result (that is, imaging data) of the wavefront measurement system 6 is input to the arithmetic processing unit 72 via the input interface 71. The interference type wavefront measurement system 6 is disclosed in, for example, US Patent Application Publication No. 2015/0160073.

  Thereafter, the arithmetic processing unit 72 calculates the wavefront aberration of the projection optical system 3 based on the measurement result of the wavefront measurement system 6 (that is, information on the wavefront of the exposure light EL via the projection optical form 3). That is, the arithmetic processing unit 72 calculates the wavefront aberration of the projection optical system 3 under the illumination condition for image plane measurement. As a result, aberration information relating to wavefront aberration is acquired.

(2-4) Processing for calculating the position of the image plane Next, the flow of processing for calculating the position of the image plane in step S4 in FIG. 2 will be described with reference to FIG. FIG. 6 is a flowchart showing a flow of processing for calculating the position of the image plane in step S4 of FIG.

  As shown in FIG. 6, the arithmetic processing unit 72 is based on the image information acquired in step S <b> 1, and the optical axis direction of the image plane on which the projection optical system 3 forms an image of the test pattern under the test illumination conditions ( First position information regarding the position in the Z-axis direction is provisionally calculated (step S31). Specifically, the arithmetic processing unit 72 defocuses at each measurement point Q (i, j) from the state of the resist image at each measurement point Q (i, j) in each shot area based on the image information. Amount (that is, the amount of deviation from the best focus position of the surface of the substrate 41 on which each measurement point Q (i, j) is set, and substantially the amount of deviation of the surface of the substrate 41 from the image plane. Amount). Note that the processing for calculating the defocus amount may be the same as the processing described in the specification of US Patent Application Publication No. 20111/212389, and thus detailed description thereof is omitted. Thereafter, the arithmetic processing unit 72 calculates the position in the optical axis direction of the image plane on which the projection optical system 3 forms an image of the test pattern, based on the defocus amount at each measurement point Q (i, j). As an example, the arithmetic processing unit 72 calculates the average value of defocus at each measurement point Q (i, j) as a deviation amount from the image plane of the surface of the substrate 41, and the deviation amount of the substrate 41 is calculated by the deviation amount. The position of the optical surface set at a position shifted from the surface may be calculated as the position in the optical axis direction of the image surface on which the projection optical system 3 forms the image of the test pattern.

  Here, as described above, the test pattern is different from the measurement target pattern. For this reason, the position in the optical axis direction of the image plane indicated by the first position information is different from the position in the optical axis direction of the image plane on which the projection optical system 3 forms an image of the measurement target pattern. Furthermore, the test illumination condition may be different from the measurement object illumination condition. In this case, considering that the influence (that is, imaging performance) of the wavefront aberration of the projection optical system 3 varies according to the illumination condition of the illumination system 2, the light on the image plane indicated by the first position information The position in the axial direction is different from the position in the optical axis direction of the image plane on which the projection optical system 3 forms an image under the measurement target illumination conditions. Therefore, in the present embodiment, the arithmetic processing unit 72 performs the processing from step S32 to step S35 described below, so that the projection optical system 3 can be obtained from the first position information under the illumination conditions for image plane measurement. Calculates the position of the image plane on which the test pattern image is formed.

  Specifically, the arithmetic processing unit 72 is based on the first position information acquired in step S31 and the aberration information acquired in step S2, and the virtual projection optical system 3 (hereinafter referred to as wavefront aberration is not present) having no wavefront aberration. The non-existent virtual projection optical system 3 is referred to as “virtual projection optical system 3a” to temporarily calculate the second position information regarding the position in the optical axis direction of the image plane on which the test pattern image is formed (step) S32). Specifically, the arithmetic processing unit 72 excludes a fluctuation component of the position in the optical axis direction of the image plane caused by the wavefront aberration indicated by the aberration information from the position in the optical axis direction of the image plane indicated by the first position information. . That is, the arithmetic processing unit 72 eliminates a fluctuation component caused by the influence of wavefront aberration on the position of the image plane in the optical axis direction from the position of the image plane indicated by the first position information. As a result, the arithmetic processing unit 72 can calculate the position in the optical axis direction of the image plane on which the virtual projection optical system 3a forms an image of the test pattern.

  Thereafter, the arithmetic processing unit 72 specifies the measurement target illumination condition and the measurement target pattern (step S33). That is, the arithmetic processing unit 72 specifies what illumination condition the measurement target illumination condition is. Furthermore, the arithmetic processing unit 72 specifies what mask pattern the measurement target pattern is.

  Thereafter, the arithmetic processing unit 72 specifies the aberration sensitivity of the projection optical system 3 under the measurement target illumination condition (step S34). Specifically, the arithmetic processing unit 72 specifies the aberration sensitivity of the projection optical system 3 under the measurement target illumination condition from the aberration sensitivity data. The aberration sensitivity data defines the relationship between the illumination conditions and the wavefront aberration (particularly, the aberration sensitivity) of the projection optical system 3. As an example of such aberration sensitivity data, for example, a database including a Zernike Sensitivity Table (Zernike Sensitivity) can be cited. The Zernike sensitivity table shows, for example, the amount of change (for example, the amount of change per 1λ) in each term of the Zernike polynomial of the wavefront aberration (that is, imaging performance) of the projection optical system 3 calculated under a certain illumination condition. The database includes each of a plurality of different illumination conditions.

  The aberration sensitivity data is input to the arithmetic processing unit 72 via the input interface 71. The aberration sensitivity data may be input to the arithmetic processing unit 72 via an input interface 71 from an internal storage device (not shown) provided in the exposure apparatus EX. The aberration sensitivity data may be input to the arithmetic processing unit 72 via the input interface 71 from an external storage device (not shown) that can be attached to and detached from the exposure apparatus EX. The aberration sensitivity data may be input to the arithmetic processing unit 72 via the input interface 71 from a network line to which the exposure apparatus EX is connected. In any case, the aberration sensitivity data is prepared in advance, and the prepared aberration sensitivity data is appropriately referred to by the arithmetic processing unit 72.

  Thereafter, the arithmetic processing unit 72 projects the projection optical system under the measurement target illumination condition based on the second position information calculated in step S32, the measurement target pattern specified in step S33, and the aberration sensitivity specified in step S34. 3 calculates the position in the optical axis direction of the image plane on which the test pattern image is formed (step S35). Specifically, for example, the arithmetic processing unit 72 generates a simulation model in which the virtual projection optical system 3a having no wavefront aberration forms an image of a test pattern based on the second position information and the measurement target pattern. Thereafter, the arithmetic processing unit 72 applies the measurement target pattern instead of the test pattern to the simulation model, so that the virtual projection optical system 3a having no wavefront aberration forms an image of the measurement target pattern. The position in the optical axis direction is calculated. Thereafter, the arithmetic processing unit 72 adds a fluctuation component of the position of the image plane in the optical axis caused by the wavefront aberration according to the specified aberration sensitivity to the calculated position of the image plane in the optical axis direction. That is, the arithmetic processing unit 72 sets the position of the image plane in the optical axis direction due to the wavefront aberration of the projection optical system 3 under the measurement target illumination condition with respect to the calculated position of the image plane in the optical axis direction. Add variable components. As a result, the arithmetic processing unit 72 can calculate the position in the optical axis direction of the image plane on which the projection optical system 3 forms an image of the measurement target pattern under the measurement target illumination conditions.

  Thereafter, the arithmetic processing unit 72 determines whether or not to change at least one of the measurement target illumination condition and the measurement target pattern (step S36). That is, the arithmetic processing unit 72 has already determined the position of the image plane in the optical axis direction under another measurement target illumination condition that is different from the one measurement target illumination condition in which the position of the image plane in the optical axis direction has already been calculated. It is determined whether or not to calculate the position in the optical axis direction of the image plane on which the image of one calculated measurement target pattern is formed. In addition, the arithmetic processing unit 72 includes a measurement target pattern that has already calculated the position of the image plane in the optical axis direction under a measurement target illumination condition that has already calculated the position of the image plane in the optical axis direction. Determines whether to calculate the position in the optical axis direction of the image plane on which the image of another different measurement target pattern is formed. Further, the arithmetic processing unit 72 has already determined the position of the image plane in the optical axis direction under another measurement target illumination condition different from the one measurement target illumination condition in which the position of the image plane in the optical axis direction has already been calculated. It is determined whether or not to calculate the position in the optical axis direction of the image plane on which an image of another measurement target pattern different from the already calculated one measurement target pattern is formed.

  As a result of the determination in step S36, when it is determined that at least one of the measurement target illumination condition and the measurement target pattern is to be changed (step S36: Yes), the arithmetic processing unit 72 performs the processing subsequent to step S33 again. That is, the arithmetic processing unit 72 changes the measurement target illumination condition and / or the measurement target pattern in step S33, and then performs the processes in and after step S34. On the other hand, as a result of the determination in step S36, when it is determined that neither the measurement target illumination condition nor the measurement target pattern is changed (step S36: No), the arithmetic processing unit 72 ends the process illustrated in FIG. To do.

(3) Technical Effects As described above, in the present embodiment, the exposure apparatus EX does not actually measure the image of the measurement target pattern formed by the projection optical system 3 under the measurement target illumination conditions. The projection optical system 3 can calculate the position in the optical axis direction of the image plane on which the image of the measurement target pattern is formed under the measurement target illumination condition. In other words, the exposure apparatus EX performs projection under the measurement target illumination condition by simulation based on the position in the optical axis direction of the image plane on which the projection optical system 3 forms an image of the test pattern under the test illumination condition. The position in the optical axis direction of the image plane on which the optical system 3 forms the image of the measurement target pattern can be calculated. For this reason, the image of the measurement target pattern formed by the projection optical system 3 under the measurement target illumination condition (for example, a resist image) is compared with the exposure apparatus of the first comparative example that actually needs to be measured. The time required for calculating (that is, measuring) the position of the surface in the optical axis direction is shortened.

  Furthermore, in this embodiment, when the exposure apparatus EX measures an image formed by the projection optical system 3 under the test illumination conditions, the projection optical system 3 captures an image under a plurality of different measurement target illumination conditions. The positions in the optical axis direction of a plurality of image planes formed respectively can be calculated. That is, the exposure apparatus EX may not actually measure a plurality of images (for example, resist images) formed by the projection optical system 3 under a plurality of measurement target illumination conditions. For this reason, compared with the exposure apparatus of the 2nd comparative example which needs to actually measure a plurality of images which each projection optical system 3 forms under a plurality of measurement object illumination conditions, a plurality of different measurement object illuminations The time required for calculating (that is, measuring) the positions of the plurality of image planes corresponding to the conditions in the optical axis direction is reduced.

  Furthermore, in this embodiment, if the exposure apparatus EX measures the image of the test pattern formed by the projection optical system 3, the projection optical system 3 forms a plurality of image planes that respectively form a plurality of different measurement target patterns. The position in the optical axis direction can be calculated. That is, the exposure apparatus EX may not actually measure a plurality of different measurement target patterns formed by the projection optical system 3 or a plurality of different test pattern images (for example, resist images). Therefore, a plurality of different measurement target patterns compared to the exposure apparatus of the third comparative example that actually needs to measure a plurality of different measurement target patterns formed by the projection optical system 3 or a plurality of different test pattern images. The time required for calculating (that is, measuring) the positions in the optical axis direction of a plurality of image planes corresponding to is reduced.

(4) Modification In the above description, the image measurement system 5 is arranged on the side surface of the projection optical system 3. However, as long as the image measurement system 5 can capture the substrate 41 (particularly, a resist image), the image measurement system 5 may be arranged at an arbitrary position. Alternatively, the exposure apparatus EX may not include the image measurement system 5. In this case, the substrate 41 (particularly, the resist image) may be picked up by another image measurement system arranged outside the exposure apparatus EX. In the above description, the image measurement system 5 captures a resist image formed on the substrate 41. However, the image measurement system 5 may measure an aerial image by the projection optical system 3.

  The exposure apparatus EX may include an alignment system that can detect an alignment mark formed on the substrate 41. The detection result of the alignment mark by the alignment system is output to the control device 7. Based on the detection result of the alignment mark, the control device 7 performs an alignment operation for aligning the device pattern already formed on the substrate 41 and the device pattern to be newly transferred on the substrate 41. . In this case, when the alignment system is an alignment system that detects an alignment mark by imaging the alignment mark, such an alignment system may also be used as the image measurement system 5 described above. An example of an alignment system that can image an alignment mark is an FIA (Field Image Alignment) type alignment system.

  In the above description, the test mask 11a used when acquiring image information is a phase shift mask that can be used for evaluating the focus position of the projection optical system 3 using the PSFM method. However, the test mask 11a may be a mask that can be used to evaluate the focus position of the projection optical system 3 using a method different from the PSFM method. For example, the test mask 11a may be a mask that can be used to evaluate the focus position of the projection optical system 3 using the CF (Contrast Focus) method. In the CF method, a predetermined mask pattern is transferred onto the substrate 41 while the position of the substrate 41 in the direction along the optical axis AX of the projection optical system 3 is changed stepwise, and the transferred predetermined mask is also transferred. In this method, the focus position is evaluated based on the contrast of the resist image of the pattern. Alternatively, the test mask 11a is not limited to a mask for evaluating the focus position of the projection optical system 3, and may be an arbitrary mask on which an arbitrary test pattern capable of forming a resist image is formed. The test mask 11a may not be a phase shift mask.

  In the above description, since the test mask 11a is a phase shift mask that can be used for evaluating the focus position of the projection optical system 3 using the PSFM method, the control device 7 performs each measurement in step S31 of FIG. A defocus amount at each measurement point Q (i, j) is calculated from the state of the resist image at the point Q (i, j), and then based on the defocus amount at each measurement point Q (i, j). The position in the optical axis direction of the image plane on which the test pattern image is formed is calculated. However, if the test mask 11a is not a phase shift mask that can be used to evaluate the focus position of the projection optical system 3 using the PSFM method, the control device 7 may use any method based on the resist image (in particular, the test mask 11a). The position in the optical axis direction of the image plane on which the test pattern image is formed may be calculated by a method suitable for the test pattern formed on the mask 11a.

  In the above description, the test pattern used when acquiring the image information is different from the measurement target pattern. However, the test pattern may be the same as the measurement target pattern. In this case, when the test illumination condition is the same as the desired illumination condition, the position in the optical axis direction of the image plane indicated by the second position information provisionally calculated in step S32 in FIG. Under the conditions, the projection optical system 3 corresponds to the position in the optical axis direction of the image plane on which the image of the measurement target pattern is formed. Therefore, the arithmetic processing unit 72 does not need to perform the processing after step S33 in FIG. However, when the test illumination condition is different from the desired illumination condition, the arithmetic processing unit 72 performs the processing after step S33 in FIG. 6 so that the projection optical system 3 can measure the measurement target pattern under the desired illumination condition. The position in the optical axis direction of the image plane forming the image is calculated.

  In the above description, the wavefront measuring system 6 is disposed on the substrate stage 4. However, as long as the wavefront measuring system 6 can measure the wavefront of the exposure light EL via the projection optical system 3, the wavefront measuring system 6 may be arranged at an arbitrary position. For example, the wavefront measuring system 6 may be disposed on the mask stage 1. For example, the wavefront measuring system 6 may be disposed on a support member that is supported by the mask stage 1. When the exposure apparatus EX includes a measurement stage that can move on the side of the substrate stage 4 in addition to the substrate stage 4, the wavefront measurement system 6 may be disposed on the measurement stage.

  In the above description, the exposure apparatus EX exposes the substrate 41 such as a semiconductor substrate. However, the exposure apparatus EX may expose an arbitrary object such as a glass plate, a ceramic substrate, a film member, or mask blanks. The exposure apparatus EX may be an exposure apparatus for manufacturing a liquid crystal display element or a display. The exposure apparatus EX may be an exposure apparatus for manufacturing at least one of a thin film magnetic head, an imaging device (for example, CCD), a micromachine, a MEMS, a DNA chip, and a mask 11 (or reticle).

  A device such as a semiconductor device may be manufactured through the steps shown in FIG. The steps for manufacturing the device include: step S201 for performing function and performance design of the device; step S202 for manufacturing the mask 11 based on the function and performance design; step S203 for manufacturing the substrate 41 which is the base material of the device; Step S204 for exposing the substrate 41 with the exposure light EL from 11 and developing the exposed substrate 41, Step S205 including device assembly processing (processing processing such as dicing processing, bonding processing, and package processing) and inspection step S206 May be included.

  The configuration requirements of the above-described embodiments can be combined as appropriate. Some of the requirements of the above-described embodiment may not be used. In addition, as long as it is permitted by law, the disclosure of all published publications and US patents related to the exposure apparatus and the like cited in the above-described embodiments are incorporated herein by reference.

  Further, the present invention can be appropriately changed without departing from the gist or the idea of the invention that can be read from the claims and the entire specification, and an evaluation apparatus and an evaluation method, an image plane measuring apparatus, and the like accompanying such a change, An image plane measuring method, an exposure apparatus, an exposure method, and a device manufacturing method are also included in the technical idea of the present invention.

EX exposure apparatus 1 mask stage 11 mask 2 illumination system 3 projection optical system 4 substrate stage 41 substrate 5 image measurement system 6 wavefront measurement system 7 controller 71 input interface 72 arithmetic processing unit

Claims (26)

An image plane measuring device that measures the position of the image plane of a projection optical system that projects an image of a desired pattern onto an image plane with exposure light,
An input interface for inputting first information relating to a state of an image formed by the exposure light via the projection optical system and second information relating to characteristics of the projection optical system;
A controller for calculating the position of the image plane using the first and second information. The image plane measurement apparatus according to claim 1, wherein the characteristic includes an aberration. The first information includes information on a state of an image formed at a first position in a projection plane on which the exposure light is projected,
The image plane measurement device according to claim 1, wherein the second information includes information related to the characteristic of exposure light that passes through a first optical path in the projection optical system and reaches the first position. The first information includes information regarding images formed at each of a plurality of second positions in a projection plane on which the exposure light is projected,
The said 2nd information contains the information regarding the said characteristic of the exposure light which each passes through each of several 2nd optical path in the said projection optical system, and reaches | attains each of these 2nd position. The image plane measuring device according to one item. The first information includes a measurement result of a first measurement device capable of measuring the image by the projection optical system,
5. The image plane measurement device according to claim 1, wherein the second information includes a measurement result of a second measurement device capable of measuring the exposure light via the projection optical system. The first measuring device can measure the state of the image by the projection optical system,
The image plane measurement apparatus according to claim 5, wherein the second measurement apparatus is capable of measuring a wavefront of the exposure light via the projection optical system. The image plane measurement device according to claim 6, wherein the first measurement device is capable of measuring a pattern image formed on a photosensitive material layer provided on a substrate by the exposure light passing through the projection optical system. . The controller (i) tentatively calculates the position of the image plane based on the state of the image indicated by the first information, and (ii) calculates the second position from the tentatively calculated position of the image plane. The image plane measurement device according to claim 1, wherein the position of the image plane is calculated by eliminating the influence of the characteristic indicated by the information on the position of the image plane. The image according to any one of claims 1 to 8, wherein the controller calculates a position of the image plane on which an image of the first mask pattern is formed by the exposure light through the first mask pattern. Surface measuring device. The first information includes information regarding a state of an image of a second mask pattern different from the first mask pattern,
The controller (i) tentatively calculates the position of the first image plane on which the image of the second mask pattern is formed based on the state of the image indicated by the first information, and (ii) The position of the second image plane obtained by eliminating the influence of the characteristics indicated by the second information on the position of the first image plane from the provisionally calculated position of the first image plane. (Iii) the position of the second image plane calculated provisionally, the first mask pattern, and the state of the exposure light used when forming the image of the first mask pattern The image plane measurement apparatus according to claim 9, wherein the position of the image plane on which the image of the first mask pattern is formed is calculated using the characteristics of the projection optical system corresponding to the above. The first information includes information on a state of an image formed by the projection optical system under a first illumination condition,
The second information includes information on characteristics of the projection optical system under the first illumination condition,
The controller calculates at least one of a position of the image plane under the first illumination condition and a position of the image plane under a second illumination condition different from the first illumination condition. The image plane measuring device according to any one of 1 to 10. The controller calculates the position of the image plane under the first illumination condition based on the first and second information,
The controller is based on the second illumination condition based on the position of the image plane under the first illumination condition and the characteristics of the projection optical system under the second illumination condition. The image plane measuring device according to claim 11, wherein the position of the image plane is calculated. The image plane measurement apparatus according to claim 11, wherein third information related to characteristics of the projection optical system under the second illumination condition is input to the input interface. An image plane measuring device that measures the position of the image plane of a projection optical system that projects an image of a desired pattern onto an image plane with exposure light,
First information regarding the state of an image formed by the projection optical system under the first illumination condition and second information regarding the characteristics of the projection optical system under the first illumination condition are input. An input interface;
A controller for calculating the position of the image plane using the first and second information. The image plane measurement device according to claim 14, wherein the controller calculates a position of the image plane under a second illumination condition different from the first illumination condition. Third information on the characteristics of the projection optical system under the second illumination condition is input to the input interface,
The image plane measurement device according to claim 15, wherein the controller calculates the position of the image plane under the second illumination condition using the third information from the first information. An image plane measurement method for measuring a position of the image plane of a projection optical system that projects an image of a desired pattern onto an image plane with exposure light,
Obtaining first information relating to a state of an image formed by the exposure light via the projection optical system and second information relating to characteristics of the projection optical system;
An image plane measuring method including calculating the position of the image plane using the first and second information. An image plane measurement method for measuring a position of the image plane of a projection optical system that projects an image of a desired pattern onto an image plane with exposure light,
Obtaining first information relating to a state of an image formed by the projection optical system under a first illumination condition and second information relating to a characteristic of the projection optical system under the first illumination condition. When,
An image plane measuring method including calculating the position of the image plane using the first and second information. Further including obtaining third information relating to characteristics of the projection optical system under a second illumination condition different from the first illumination condition;
The image plane measurement method according to claim 17, wherein the calculating calculates the position of the image plane under the second illumination condition using the first to third information. Further comprising forming a pattern image on a substrate coated with a photosensitive material;
The image plane measurement method according to claim 17, wherein the acquiring includes observing the pattern image and acquiring the first information.   An exposure apparatus comprising the image plane measuring device according to any one of claims 1 to 16.   An exposure apparatus that exposes a substrate using a measurement result of the image plane measurement method according to any one of claims 17 to 20.   The exposure method which exposes a board | substrate using the image surface measuring device as described in any one of Claims 1-16.   The exposure method which exposes a board | substrate using the measurement result of the image surface measuring method as described in any one of Claims 17-20. A substrate coated with a photosensitive material is exposed using the exposure method according to claim 23 or 24, and a desired mask pattern is transferred to the substrate.
Developing the exposed photosensitive material to form an exposure pattern layer corresponding to the desired mask pattern;
A device manufacturing method for processing the substrate through the exposure pattern layer.   A computer program for causing a computer to execute the image plane measurement method according to any one of claims 17 to 20.

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