JP2023072533A - Exposure device, exposure method, and article manufacturing method - Google Patents

Abstract

To provide a technique advantageous for improving a focus residue.SOLUTION: An exposure device for exposing a shot region of a substrate through an original plate includes a measurement part for measuring positions in a height direction of a plurality of measurement points of exposure regions, for each of the exposure regions becoming units of exposure for the shot region, and a control part, wherein the control part determines second-order or higher approximation functions expressing a cross-sectional shape of the surface of the exposure region by approximation for each of the exposure regions on the basis of the positions in the height direction of the plurality of measurement points measured by the measurement part, determines a representative plane representatively expressing the cross-sectional shape of the surface of the exposure region for each of the exposure regions on the basis of the approximation function, and controls the position of the substrate in the height direction when the exposure regions are exposed on the basis of the representative plane for each of the exposure regions.SELECTED DRAWING: Figure 1

Description

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

2. Description of the Related Art In a photolithography process for manufacturing devices such as semiconductor elements, an exposure apparatus is used that transfers an original (reticle or mask) onto a substrate via a projection optical system. As such exposure apparatuses, generally known are an exposure apparatus (stepper) that employs a step-and-repeat method and an exposure apparatus (scanner) that employs a step-and-scan method.

In order to accurately transfer the pattern of the original onto the substrate, the exposure apparatus is required to align the original and the substrate, as well as perform focus positioning with high accuracy. have also been proposed (see Patent Documents 1 to 3). Note that focus alignment means alignment between the image plane of the projection optical system and the surface of the substrate.

In Patent Document 1, the processed region (exposure region) is represented by a polynomial (approximate surface shape) from the result of measuring the position of the processed region (exposure region) of the substrate, and the focus correction value is feedforward processed to calculate the focus residual. Techniques for improving are disclosed. Patent Document 2 discloses a technique for correcting an offset value to be subtracted from the height values (measured values) of the surface of a plurality of sample shots on a substrate using the amount of error (inclination) generated in the step of calculating the offset value. is disclosed. In Patent Document 3, a surface shape function indicating the surface shape of the substrate is determined from the results of measuring the surface position of the substrate at a plurality of points, and the surface position (data) of the substrate is corrected based on the constant term of the surface shape function. A technique for doing so is disclosed.

JP 2005-129674 A Japanese Patent No. 6253269 Japanese Patent No. 2130641

However, in the prior art, when the topography shape of the exposure area of the substrate is not planar, for example, it is a secondary shape, depending on the setting of the measurement points on the substrate, the focus alignment residual error, that is, the focus residual error increases. In the prior art, the least-squares plane calculated from measurement points (topography representative points) and each measurement value is used as the exposure correction plane.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems of the prior art, and an exemplary object of the present invention is to provide an advantageous technique for improving the focus residual.

To achieve the above object, an exposure apparatus as one aspect of the present invention is an exposure apparatus that exposes a shot area of a substrate through an original, wherein each exposure area that is a unit of exposure for the shot area is , a measuring unit that measures the positions of a plurality of measurement points in the exposure region in the height direction, and a control unit, wherein the control unit measures, for each of the exposure regions, the Based on the positions of the plurality of measurement points in the height direction, a quadratic or higher approximation function that approximates the cross-sectional shape of the surface of the exposure region is obtained, and for each of the exposure regions, based on the approximation function, A representative plane representing the cross-sectional shape of the surface of the exposure region is obtained, and for each of the exposure regions, the position of the substrate in the height direction when the exposure region is exposed is determined based on the representative plane. It is characterized by controlling.

Further objects or other aspects of the present invention will be made clear by the 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 improving focus residuals.

1 is a schematic diagram showing the configuration of an exposure apparatus as one aspect of the present invention; FIG. FIG. 3 is a diagram showing an example of the relationship between an irradiation system, a light receiving system, and measurement points on a substrate; 4 is a diagram showing the relationship between measurement points formed in shot areas on a substrate and exposure areas; FIG. FIG. 4 is a diagram showing the topography shape of a substrate and measurement points; 5 is a cross-sectional view of the topographical shape shown in FIG. 4; FIG. FIG. 4 is a diagram showing the topography shape of a substrate and measurement points; FIG. 4 is a diagram showing the topography shape of a substrate and measurement points; It is a figure which shows an example of the result of focus measurement performed with respect to the whole surface of a board|substrate. FIG. 4 is a diagram showing the topography shape of a substrate and measurement points; FIG. 4 is a diagram showing the topography shape of a substrate and measurement points;

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.

FIG. 1 is a schematic diagram showing the configuration of an exposure apparatus 80 as one aspect of the present invention. The exposure apparatus 80 is a lithography apparatus used in a lithography process, which is a manufacturing process of devices such as semiconductor elements, and forms a pattern on a substrate using an original plate (reticle or mask). The exposure device 80 performs an exposure process of exposing the substrate through the original and transferring the pattern of the original onto the substrate.

In this embodiment, the exposure apparatus 80 is a step-and-scan type exposure apparatus (scanner) that exposes the substrate while driving the original and the substrate in the scanning direction (scanning exposure) to transfer the pattern of the original onto the substrate. ). However, the exposure device 80 can also employ a step-and-repeat method or other exposure method.

In this specification and the accompanying drawings, the direction along the optical axis of the projection optical system 14, which will be described later, is defined as the Z-axis, and the direction parallel to the plane perpendicular to the Z-axis and perpendicular to each other is defined as the X-axis. , indicates the direction in an XYZ coordinate system with the Y axis. The directions parallel to the X, Y, and Z axes in the XYZ coordinate system are defined as the X direction, Y direction, and Z direction, respectively.

As shown in FIG. 1, the exposure apparatus 80 includes an illumination optical system 11, an original stage 13 that holds an original 12, a projection optical system 14, a substrate stage 16 that holds a substrate 15, and a first measuring section . , a second measuring unit 19 , a third measuring unit 17 , and a control unit 20 .

The control unit 20 is composed of, for example, a computer (information processing device) including a CPU, a memory, etc., and comprehensively controls each unit of the exposure apparatus 80 according to a program stored in a storage unit. In this embodiment, the control unit 20 controls an exposure process of transferring a pattern formed on the original 12 to the substrate 15 (scanning and exposing the substrate 15).

The illumination optical system 11 includes a light shielding member such as a masking blade, and shapes light emitted from a light source (not shown) such as an excimer laser into, for example, a band-shaped or arc-shaped slit light having a longitudinal direction in the X direction. , illuminates a portion of the original plate 12 with such slit light.

The original 12 and the substrate 15 are held by an original stage 13 and a substrate stage 16, respectively, and arranged at optically conjugate positions via the projection optical system 14. FIG.

The projection optical system 14 has a predetermined projection magnification (for example, 1/2 times or 1/4 times) and projects the pattern formed on the original 12 onto the substrate 15 . A region of the substrate 15 onto which the pattern of the original 12 is projected (that is, a region irradiated with slit light and a unit of exposure for a shot region) is hereinafter referred to as an exposure region 21 .

The original stage 13 and the substrate stage 16 are configured to be drivable in a direction (eg, Y direction) perpendicular to the optical axis of the projection optical system 14 (the optical axis of the slit light). The original stage 13 and the substrate stage 16 are synchronized with each other and relatively driven (scanned) at a speed ratio corresponding to the projection magnification of the projection optical system 14 . As a result, the pattern of the original 12 can be transferred onto the substrate 15 (shot area) by scanning the exposure area 21 on the substrate. By sequentially repeating such scanning exposure for each of a plurality of shot areas on the substrate, exposure processing for one substrate 15 is completed.

The first measurement unit 18 includes, for example, a laser interferometer, and measures the position of the original stage 13 . The laser interferometer included in the first measuring unit 18 irradiates, for example, a laser beam to the reflector 13a provided on the original stage 13, and detects the laser beam reflected by the reflector 13a, thereby measuring the original stage. Measure the displacement from the reference position at 13 . The first measuring unit 18 can acquire the current position of the original stage 13 based on the displacement of the original stage 13 from the reference position.

The second measurement unit 19 includes, for example, a laser interferometer and measures the position of the substrate stage 16 . The laser interferometer included in the second measurement unit 19 irradiates, for example, a laser beam to the reflector 16a provided on the substrate stage 16, and detects the laser beam reflected by the reflector 16a, thereby detecting the substrate stage. Measure the displacement from the reference position at 16 . The second measurement unit 19 can acquire the current position of the substrate stage 16 based on the displacement of the substrate stage 16 from the reference position.

Based on the current position of the original stage 13 acquired by the first measurement unit 18 and the current position of the substrate stage 16 acquired by the second measurement unit 19, the control unit 20 controls the original stage 13 and the substrate stage. Driving in 16 XY directions is controlled. In this embodiment, each of the first measurement unit 18 and the second measurement unit 19 uses a laser interferometer to measure the position of the original stage 13 and the position of the substrate stage 16. For example, an encoder may be used without limitation.

The third measuring unit 17 is used to align the surface of the substrate 15 (hereinafter referred to as "substrate surface") with the image plane of the projection optical system 14, and has a function of measuring the position and tilt of the substrate surface. In this embodiment, the third measurement unit 17 measures the surface position (height direction) of the measurement target location (measurement point) in the shot area of the substrate 15 held by the substrate stage 16 while the substrate stage 16 is being driven. position).

The third measurement unit 17 is configured, for example, as an oblique incidence type measurement unit that obliquely irradiates the substrate 15 with light. The third measurement unit 17 includes an irradiation system 17 a that irradiates the substrate 15 with light and a light receiving system 17 b that receives the light reflected by the substrate 15 .

The irradiation system 17a includes a light source 70, a collimator lens 71, a slit member 72, an irradiation optical system 73, and a mirror 74, for example. The light receiving system 17b includes, for example, a mirror 75, a light receiving optical system 76, a correction optical system 77, a photoelectric conversion element 78, and a processing section 79.

The light source 70 includes a lamp, a light-emitting diode, or the like, and emits light of a wavelength to which the resist agent (photosensitive agent) on the substrate is not sensitive. The collimator lens 71 converts the light emitted from the light source 70 into parallel light with a substantially uniform cross-sectional intensity distribution. The slit member 72 is configured by pasting a pair of prisms (prism-shaped members) so that their slopes face each other. It is formed using a light shielding film such as The irradiation optical system 73 is a double-telecentric system, and directs each of the lights that have passed through the plurality of openings of the slit member 72 to a plurality of measurement target locations (measurement points) in the shot area of the substrate 15 via a mirror 74. Make it incident (guide light).

With respect to the irradiation optical system 73, the plane (bonding surface) on which the aperture is formed and the substrate surface are set so as to satisfy the Scheimpflug condition. In this embodiment, the incident angle of the light incident on the substrate 15 from the irradiation optical system 73 (the angle formed with the optical axis of the projection optical system 14) is 70 degrees or more. Further, as shown in FIG. 2, the irradiation system 17a emits light from a direction forming an angle θ (for example, 22.5 degrees) with respect to the scanning direction (Y direction) in the direction (XY direction) parallel to the substrate surface. It is configured to allow light to enter. In this way, by causing a plurality of (for example, nine) light beams to enter a plurality of (for example, nine) measurement points on the substrate, that is, the measurement points 30, the substrate surface surface position can be measured independently. FIG. 2 is a diagram showing an example of the relationship between the irradiation system 17a, the light receiving system 17b, and the measurement points 30 on the substrate.

A plurality of lights reflected at each measurement target location (measurement point 30 ) on the substrate enter a light receiving optical system 76 via a mirror 75 . The light receiving optical system 76 is a double telecentric system. The light-receiving optical system 76 includes an aperture that is provided in common for a plurality of lights reflected at each measurement target location on the substrate. Blocks high-order diffracted light (noise light).

The correcting optical system 77 includes a plurality of (for example, nine) correcting lenses, and forms an image of a plurality of lights that have passed through the light receiving optical system 76 on the photoelectric conversion surface (light receiving surface) of the photoelectric conversion element 78. A plurality of pinhole images are formed on the photoelectric conversion surface. As the photoelectric conversion element 78, for example, a CCD line sensor, a CMOS line sensor, or the like is used. Based on the position of each pinhole image formed on (the photoelectric conversion surface of) the photoelectric conversion element 78, the processing unit 79 calculates the surface position of the substrate surface at each measurement target location on the substrate, that is, the measurement point 30. (get. In the light receiving system 17b, inclination correction is performed so that each measurement point on the substrate and the photoelectric conversion surface of the photoelectric conversion element 78 are conjugated with each other. Therefore, the position of each pinhole image formed on the photoelectric conversion surface of the photoelectric conversion element 78 does not change depending on the local inclination of each measurement point on the substrate.

By configuring the irradiation system 17a and the light receiving system 17b in this way, the third measurement unit 17 can perform each measurement on the substrate from the position of each pinhole image formed on the photoelectric conversion surface of the photoelectric conversion element 78. The surface position of the substrate plane at points can be measured. Then, based on the measurement result of the third measuring unit 17, the control unit 20 drives the substrate stage 16 in the Z direction (focus driving) so that the substrate surface of the substrate 15 matches the target surface (target height position). ) is controlled. Here, the target plane is the image plane of the pattern of the original 12, that is, the position of the image plane of the projection optical system 14 (best focus position (optimum exposure position)). However, the target plane does not mean a position that completely matches the position of the image plane of the projection optical system 14, but includes the range of the allowable depth of focus.

FIG. 3 shows nine measurement points 30 (30a ₁ to 30a ₃ , 30b ₁ to 30b ₃ , 30c ₁ to 30c ₃ ) formed in the shot area 15a on the substrate by the third measurement unit 17 and the exposure area 21. FIG. 4 is a diagram showing relationships; The exposure area 21 is a rectangular area indicated by broken lines in FIG. The measurement points 30a ₁ to 30a ₃ are measurement points formed in (the inside of) the exposure area 21 . The measurement points 30a ₁ to 30a ₃ are measurement points at which so-called focus measurement is performed, in which the surface positions of the substrate surface at the measurement target locations on the substrate are measured in parallel with the exposure of the measurement target locations on the substrate. The measurement points 30b ₁ to 30b ₃ and 30c ₁ to 30c ₃ are measurement points formed at positions separated from the measurement points 30a ₁ to 30a ₃ formed in the exposure area 21 by a distance Lp in the scanning direction (Y direction). It is a point. At the measurement points 30b ₁ to 30b ₃ and 30c ₁ to 30c ₃ , the surface positions of the substrate surface at the measurement target locations are measured prior to the exposure of the measurement target locations on the substrate, so-called focus measurement. It is a point.

The control unit 20 switches the measurement points used for measuring the surface position of the measurement target location on the substrate, that is, for focus measurement, according to the direction (scanning direction) in which the substrate stage 16 is driven. For example, referring to FIG. 3, when scanning exposure is performed by driving the substrate stage 16 in the direction indicated by the arrow F, prior to focus measurement at the measurement points 30a ₁ to 30a ₃ formed in the exposure area 21, measurement Focus measurements are made at points 30b ₁ to 30b ₃ . At this time, based on the results of focus measurement at the measurement points 30b ₁ to 30b ₃ , the control unit 20 sets a command value for arranging the surface position of the area including the measurement points 30b ₁ to 30b ₃ at the target height position. decide. Then, according to the determined command value, the control unit 20 arranges the area including the measurement points 30b ₁ to 30b ₃ at the target height position before becoming the exposure area 21 (reaching the exposure area 21). Secondly, the focus drive of the substrate stage 16 is controlled.

On the other hand, when scanning exposure is performed by driving the substrate stage 16 _in the direction indicated by the arrow R, prior to focus measurement at the measurement points _{30a 1 to} 30a ₃ formed in the exposure area 21, Focus measurement is performed. At this time, based on the results of focus measurement at the measurement points 30c ₁ to 30c ₃ , the control unit 20 sets a command value for arranging the surface position of the area including the measurement points 30c ₁ to 30c ₃ at the target height position. decide. Then, the control unit 20 drives the substrate stage 16 so that the area including the measurement points 30c ₁ to 30c ₃ is arranged at the target height position before becoming the exposure area 21 according to the determined command value. to control.

In the focus alignment, which is the alignment between the image plane of the projection optical system 14 and the substrate surface, if the topography shape of the surface of the substrate 15 (substrate surface) deviates from the plane, the focus residual error is improved. A method (exposure method) will be described.

<First embodiment>
FIG. 4 is a diagram showing a topography shape 90 of the substrate 15 and measurement points 91 (measurement positions) of the third measurement unit 17. As shown in FIG. FIG. 5 is a cross-sectional view of the topographic features 90 of the substrate 15 shown in FIG. Referring to FIGS. 4 and 5, in the present embodiment, the surface positions of the exposure region 101 of the substrate 15 are measured at a plurality of measurement points 91 (measurement of the topography shape 90), that is, focus Take measurements.

In the prior art, the least-squares plane calculated based on the surface positions (measured values) of the substrate surface at a plurality of measurement points 91 and the positions of the measurement points 91 is defined as the exposure plane, which is the target plane (target height position). 110. Here, the exposure plane 110 is a representative plane representing the surface shape of the shot area. Then, the focus drive of the substrate stage 16 is controlled so that the image plane of the projection optical system 14 and the exposure plane 110 are aligned. At this time, the point (position) where the focus residual takes the maximum value 111 is the point where the difference between the topography shape 90 and the exposure plane 110 is maximum, and the point where the image performance is most degraded during exposure.

On the other hand, in this embodiment, based on the surface positions (measured values) of the substrate surface at the plurality of measurement points 91 and the positions of the measurement points 91, a surface shape function other than a constant or a linear function, that is, a quadratic or higher surface shape function 120 is calculated. Here, the surface shape function 120 is a quadratic or higher approximation function that approximates the surface shape of the exposure region 101 (more specifically, the cross-sectional shape of the surface of the exposure region 101). The surface shape function 120 is in the plane (in the XY plane) perpendicular to the height direction (Z direction) of the substrate 15 and in the direction (X direction) perpendicular to the scanning direction (Y direction) of the master 12 and the substrate 15. approximating the surface shape of the exposure region 101 in .

For example, let the positions of the five measurement points 91 be x1, x2, x3, x4 and x5, respectively, and let the measured values of the surface positions of the substrate surface at the five measurement points 91 be z1, z2, z3, z4 and z5. When the surface shape function 120 is a quadratic function, the surface shape function 120 at the position x of the measurement point 91 is expressed by the following equation (1) using constants a, b and c.

With respect to the surface shape function 120, the positions x1 to x5 of the measurement points 91 and the measured values z1 to z5 have the relationship shown in the following formula (2).

The surface shape function 120 can be determined by solving equation (2) for the constants a, b and c.

Based on the surface shape function 120 obtained in this way, in this embodiment, an exposure plane 121, which is a target plane (target height position), is calculated. For example, the exposure plane 121 may be obtained by calculating a least-squares plane for the surface shape function 120 in the exposure region 101 . The exposure plane 121 is represented by the following equation (3) using constants p and q.

For points v1, v2, . An average value X ⁻ of the differences Xi is obtained.

From the equations (4) and (5), the variance ^s2 of the difference Xi shown in the following equation (6) is obtained.

The exposure plane 121 is calculated by finding the constants p and q that minimize the variance ^s2 of the difference Xi.

Alternatively, the surface shape function 120 may be weighted according to the surface position (measurement value) of the substrate surface measured by the third measuring unit 17 to determine the least-squares plane as the exposure plane 121 . Thereby, uniform image performance can be obtained in the exposure area 101 while avoiding local defocus.

In this embodiment, the focus drive of the substrate stage 16 is controlled so that the image plane of the projection optical system 14 and the exposure plane 121 are aligned. At this time, the point (position) where the focus residual takes the maximum value 122 is the point where the difference between the topography shape 90 and the exposure plane 121 is maximum. In this embodiment, since the exposure plane 121 is obtained from the surface shape function 120 of degree 2 or higher that approximates (reproduces) the topography shape 90, the maximum value 122 of the focus residual error in this embodiment is It is smaller than the maximum value 111 of the focus residual in the prior art. Therefore, in the present embodiment, it is possible to improve the focus residual error in the exposure area 101 and suppress deterioration of image performance during exposure.

A series of processes including focus measurement, calculation (acquisition) of the surface shape function 120, calculation of the exposure plane 121, and focus driving are performed in real time for each exposure area in one shot area. is repeated until the scanning exposure for .

<Second embodiment>
FIG. 6 shows the result of calculating a surface shape function 130 different from the surface shape function 120 for the topography shape 90 of the substrate 15 . Here, consider a case where focus measurement is performed at five measurement points 91 . When there are five measurement points 91 of the third measurement unit 17, the number of terms of the surface shape function that can be calculated as an approximation function that approximates the surface shape of the exposure area 101 is five. Therefore, the surface shape function 130, which is a quartic function (polynomial), may be an approximation function that approximates the surface shape of the exposure region 101. FIG. If the topography shape 90 of the substrate 15 is not known, the surface shape function 130, which is a quartic function, is an approximation function that passes through the measured values at the five measurement points 91 and reproduces the topography shape 90. Obtainable.

Moreover, the order and the number of terms of the surface shape function that approximates the surface shape of the exposure region 101 can be changed within the range not exceeding the number of measurement points 91 . For example, if the topographical shape 90 of the substrate 15 is symmetrical with respect to the center of the exposure area 101, the reproducibility of the topographical shape 90 is improved by setting the order of the surface shape function to even terms.

A surface shape function approximating the surface shape of the exposure region 101 may be used as the surface shape function 131, which is a non-linear function, within a range not exceeding the number of measurement points 91. FIG. In this case, it is necessary to model a nonlinear function with a high reproducibility in advance in the exposure region 101 for the topography shape 90 of the substrate 15 . In FIG. 6, the surface shape function 131 is obtained by modeling the nonlinear function as a Gaussian function. However, the nonlinear function is not limited to the Gaussian function, and may be, for example, a sine function. When the topographical shape 100 of the substrate 15 is a periodic shape in the exposure area 101, the nonlinear function is modeled as a sine function to improve the reproducibility of the surface shape function for the topographical shape 100. can be done.

<Third Embodiment>
In this embodiment, referring to FIG. 7, a method of obtaining an exposure plane that represents the topography shape 90 of the substrate 15 in consideration of the image plane that has changed due to the aberration of the projection optical system 14 will be described. Projection optics 14 may be non-planar with respect to topographic features 90 because they have a certain amount of aberration. Further, the image plane of the projection optical system 14 may not be flat due to thermal deformation of the lenses and lens barrel of the projection optical system 14 during exposure. In such a case, as shown in FIG. 7, based on corrected measured values 141 (corrected positions) obtained by correcting the measured values at the five measurement points 91 on the image plane 140 of the projection optical system 14, A surface shape function 142 that approximates the surface shape of the exposure area is calculated. As a result, the topography shape 90 of the substrate 15 can be aligned with the image plane 140 of the projection optical system 14, the focus residual error in the exposure area 101 can be improved, and the deterioration of image performance during exposure can be further suppressed. be able to.

In this embodiment, the measurement value at the measurement point 91 is corrected on the image plane 140 of the projection optical system 14, but the present invention is not limited to this. For example, a surface shape function approximating the surface shape of the exposure region, for example, the surface shape function 120 obtained in the first embodiment, is obtained from the measured values at the measurement point 91 , and the surface shape function 120 is applied to the projection optical system 14 . The image plane 140 may be corrected. Such an approach is useful when the image plane 140 of the projection optical system 14 has a simple first-order plane tilt with respect to the stage plane.

<Fourth Embodiment>
The substrate 15 to be exposed by the exposure device 80 generally includes a substrate having a rough surface. The coefficient of the surface shape function that approximates the surface shape of the exposure region of the substrate changes greatly for each focus measurement. Therefore, for each substrate or each shot area, a logic is provided for determining an abnormal value for statistical values (variance values, etc.) of the coefficients included in the surface shape function, and the quality thereof, for example, defective substrates, or , to determine whether it is a bad shot area. If the substrate is determined to be a defective substrate or a defective shot area, the fact (error message) is notified to the user (operator) via an output device such as a display device or an audio device of the exposure apparatus 80 .

Thus, in this embodiment, the statistical values of the coefficients included in the surface shape functions (approximate functions) obtained from a plurality of exposed substrates and the coefficients included in the surface shape obtained from the exposed substrates By comparing with the coefficient, it is determined whether or not the substrate or its shot area is defective. Then, the user is notified of the substrate determined to be defective (defective substrate) and the shot area determined to be defective (defective shot area).

As for the defective substrate and the defective shot area, the exposure plane may be determined from the focus measurement result (measurement value) of the third measuring unit 17 as in the conventional technique without obtaining the surface shape function. As for a defective substrate or a defective shot area, a surface shape function may be determined using measurement values at different measurement points, and an exposure plane may be determined based on the surface shape function. This makes it possible to suppress abrupt focus driving of the substrate stage 16 in a defective substrate or a defective shot area, and as a result, it is possible to improve the focus residual error.

<Fifth Embodiment>
In this embodiment, it is assumed that focus measurement is performed on the entire surface of the substrate 15 while driving the substrate stage 16 . The focus measurement for the entire surface of the substrate 15 can be realized by measuring the measurement origin of the substrate stage 16 a plurality of times at intervals smaller than the measurement interval of each measurement point on the substrate.

In the present embodiment, a measurement sequence for performing focus measurement on the entire surface of the substrate 15 is performed prior to the sequence including the exposure process, so that the topography shape 200 of the entire surface of the substrate 15 can be obtained as shown in FIG. measure. Then, for the topography shape 200 of the entire surface of the substrate 15, a topography shape 202 for each measurement step (eg, exposure region) is obtained from the layout 201 of the shot region. FIG. 8 is a diagram showing an example of the results of focus measurement performed on the entire surface of the substrate 15. As shown in FIG.

FIG. 9 shows a cross-section of topographic feature 202 at a particular metrology step. FIG. 9 also shows a plurality of measurement points 203 of the third measurement unit 17 during exposure with respect to the topography shape 202 . In the present embodiment, a plurality of different surface shape functions of second or higher order are obtained based on the surface positions (measured values) of the substrate surface at the plurality of measurement points 203 and the positions of the measurement points 203 . Specifically, for five measurement points 203, three surface shape functions 212, 213 and 214, which are smaller in number than the number of measurement points 203, are obtained. Here, the surface shape function 212 is a quadratic function (polynomial), the surface shape function 213 is a cubic function, and the surface shape function 214 is a quartic function.

FIG. 10 shows an enlarged view of the cross-sectional area 204 of the topographic features 202 shown in FIG. Now consider the respective differences 222 , 223 and 224 of the surface shape functions 212 , 213 and 214 for the topographic feature 202 in the cross-sectional area 204 of the topographic feature 202 . In this case, of the differences 222 , 223 and 224 , the surface shape function with the smallest difference is the approximation function that most approximates the topography shape 202 . In FIG. 10, since the topography shape 202 is a cubic shape, the difference 223 of the surface shape function 213, which is a cubic function, is minimized. Therefore, since the surface shape function 213 is an approximation function that most approximates the topography shape 202, the exposure plane is obtained based on the surface shape function 213, thereby most improving the focus residual error and producing an image at the time of exposure. It becomes possible to suppress the deterioration of the performance most.

By performing such processing on the entire surface of the substrate 15, a surface shape function that best reproduces the topography shape of the substrate 15 can be obtained for each measurement step. By calculating the exposure plane based on the surface shape function obtained in each measurement step, it is possible to further improve the focus residual error and further suppress the deterioration of the image performance during exposure.

In this embodiment, the exposure plane is calculated based on the surface shape function having the smallest difference from the topography shape among the plurality of mutually different surface shape functions obtained from the measured values at the plurality of measurement points. However, it is not limited to this. For example, from the viewpoint of suppressing deterioration of image performance during exposure by improving focus residual error, one surface shape function, which has an allowable range of difference from the topography shape, among a plurality of mutually different surface shape functions. Based on this, the exposure plane may be calculated.

Further, it is not necessary to perform focus measurement on the entire surface of the substrate 15 and obtain the surface shape function for each measurement step for each substrate. For example, the surface shape function is stored in the storage unit of the exposure apparatus 80, and the surface shape function stored in the storage unit is used when exposing the substrate with the same recipe or when performing periodic checks. may

As described above, according to the first to fifth embodiments, the topography shape of the surface of the substrate 15 (substrate surface) deviates from the plane during focus alignment, which is alignment between the image plane of the projection optical system 14 and the substrate surface. Focus residual can be improved even in the case of

The method for manufacturing an article according to the embodiment of the present invention is suitable for manufacturing articles such as liquid crystal display elements, semiconductor elements, flat panel displays, and MEMS. This manufacturing method includes a step of exposing a substrate coated with a photosensitive agent using the exposure apparatus 80 or the exposure method described above, and a step of developing the exposed photosensitive agent. Also, the circuit pattern is formed on the substrate by performing an etching process or an ion implantation process on the substrate using the pattern of the developed photosensitive agent as a mask. By repeating these steps of exposure, development, etching, etc., a circuit pattern consisting of a plurality of layers is formed on the substrate. In the post-process, the substrate on which the circuit pattern is formed is diced (processed), and chip mounting, bonding, and inspection processes are performed. Such manufacturing methods may also include other well-known steps (oxidation, deposition, deposition, doping, planarization, resist stripping, etc.). The method for manufacturing an article according to the present embodiment is advantageous in at least one of performance, quality, productivity and production cost of the article as compared with conventional methods.

It should be noted that the present invention is not intended to limit the lithographic apparatus to an exposure apparatus, but can also be applied to, for example, an imprint apparatus. The imprinting apparatus brings the imprinting material placed (supplied) on the substrate into contact with the mold (original plate) and applies energy for curing to the imprinting material, thereby producing a cured product with the pattern of the mold transferred. form a pattern. The present invention can also be applied to an external inspection apparatus for substrates.

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.

12: Original plate 13: Original plate stage 14: Projection optical system 15: Substrate 16: Substrate stage 17: Third measurement unit 20: Control unit 80: Exposure device

Claims (14)

An exposure apparatus that exposes a shot area of a substrate through an original,
a measurement unit that measures positions in the height direction of a plurality of measurement points in each exposure area, which is a unit of exposure for the shot area;
a control unit;
The control unit
For each of the exposure regions, a quadratic or higher approximation function that approximates the cross-sectional shape of the surface of the exposure region is obtained based on the positions in the height direction of the plurality of measurement points measured by the measurement unit. ,
For each of the exposure regions, obtaining a representative plane representative of the cross-sectional shape of the surface of the exposure region based on the approximate function;
For each of the exposure regions, controlling the position of the substrate in the height direction when exposing the exposure region based on the representative plane;
An exposure apparatus characterized by: The exposure device scans and exposes the shot area while driving the original and the substrate,
2. The exposure apparatus according to claim 1, wherein the measurement unit measures the positions of the plurality of measurement points in the height direction for each of the exposure areas before scanning and exposing the exposure area. The approximation function approximates a cross-sectional shape of the surface of the exposure region in a plane orthogonal to the height direction and in a direction orthogonal to a direction in which the original and the substrate are driven. 3. The exposure apparatus according to claim 2, wherein 4. The exposure apparatus according to any one of claims 1 to 3, wherein said control unit obtains a least-squares plane from said approximation function as said representative plane. 5. Any one of claims 1 to 4, wherein the control unit obtains the representative plane by weighting according to the height direction positions of the plurality of measurement points measured by the measurement unit. The exposure apparatus according to the item. 6. The exposure apparatus according to claim 1, wherein said approximation function is a non-linear function including a smaller number of coefficients than said plurality of measurement points. further comprising a projection optical system for projecting the pattern of the original onto the substrate;
The control unit obtains the approximation function based on corrected positions obtained by correcting the height direction positions of the plurality of measurement points measured by the measurement unit on the image plane of the projection optical system. 7. An exposure apparatus as claimed in any one of claims 1 to 6. The control unit
By comparing statistical values of coefficients included in the approximation function obtained from a plurality of exposed substrates with coefficients included in the approximation function obtained from the substrate to be exposed, it is possible to determine whether the substrate is defective. determine whether or not
8. The exposure apparatus according to any one of claims 1 to 7, wherein the substrate judged to be defective is notified. The control unit
By comparing statistical values of coefficients included in the approximation function obtained from a plurality of regions of the substrate subjected to exposure with coefficients included in the approximation function obtained from the region of the substrate subjected to exposure, Determining whether the area is defective,
8. The exposure apparatus according to any one of claims 1 to 7, wherein the area of the substrate judged to be defective is notified. The control unit
Obtaining a plurality of different approximation functions of degree two or more that approximate the surface shape of the exposure region based on the positions in the height direction of the plurality of measurement points measured by the measurement unit;
10. The representative plane is determined based on one of the plurality of approximation functions that allows a difference from the surface shape of the exposure area to be within an allowable range. The exposure apparatus according to the item. 11. The exposure apparatus according to claim 10, wherein the control unit obtains the plurality of approximation functions whose number is smaller than the number of the plurality of measurement points. 12. An exposure apparatus according to claim 10, wherein said plurality of approximation functions include coefficients of a number smaller than the number of said plurality of measurement points. An exposure method for exposing a shot area of a substrate through an original plate,
a step of measuring positions in the height direction of a plurality of measurement points in each exposure region, which is a unit of exposure for the shot region;
For each of the exposure regions, obtaining a quadratic or higher approximation function that approximates the cross-sectional shape of the surface of the exposure region based on the positions of the plurality of measurement points measured in the step in the height direction. and,
obtaining a representative plane representative of the cross-sectional shape of the surface of the exposure region for each of the exposure regions, based on the approximation function;
for each of the exposure regions, controlling the position of the substrate in the height direction when the exposure region is exposed, based on the representative plane;
An exposure method characterized by comprising: exposing a substrate using the exposure method according to claim 13;
developing the exposed substrate;
producing an article from the developed substrate;
A method for manufacturing an article, comprising:

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