JPH10284366A - Focal point position detecting equipment and focal point position detecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the optimum focal point position, by selecting a plurality of measuring points from detected results of a detecting part before and after a specified very small distance travel, on the basis of the result of an operation part. SOLUTION: A driving part 22 moves an XY stage 21 in the X direction and the Y direction by a very small distance under the command of a MCU 30. The XY stage 21 is moved by a very small distance ΔP, and the difference of measured values of hight positions before and after the movement is obtained. When one out of the obtained difference value is greater than or equal to a specified threshold value, the MCU 30 detects the measured point as a measured point positioned at a step-difference part, does not select the measured point positioned at the step-difference part, and selects a measured point which does not positioned at the step-difference part. The value averaged by using the measured value at the selected measured point is made the optimum height position for exposure in a shot region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus position detecting device and method, and more particularly to a focus position detecting device and method for an exposure apparatus used in semiconductor manufacturing.

[0002]

2. Description of the Related Art Conventionally, as a focus position detecting device used for an exposure apparatus, as disclosed in Japanese Patent Application Laid-Open No. 58-113706 proposed by the same applicant as the present application, a projection optical system has been proposed. Semiconductor wafer (hereinafter, referred to as a substrate) positioned at a position where a mask pattern is transferred by
Called wafer. ), A so-called oblique incidence type focus position detection device that irradiates detection light from an oblique direction is used.

In this focus position detecting device, the surface of a wafer is used as a surface to be inspected, and a slit-like pattern is formed on the surface to be inspected so that the longitudinal direction of the slit is a plane extending between incident light and reflected light, that is, perpendicular to the incident surface. The reflected light is projected in such a direction as to form an image on the detecting means comprising a photoelectric conversion element, and the incident position of the reflected light on the detecting means can be detected.

In recent years, with the increase in integration of LSIs, it has been desired to transfer a fine pattern to an exposure area (shot area) on a wafer. Numerical aperture NA (Numerical
Aperture) is largely composed. However, since the depth of focus of the projection optical system is reduced by increasing the numerical aperture NA, it is desired that the exposure area be more accurately and reliably positioned at the focal position (within the depth of focus) of the projection optical system.

[0005] In addition, the size of the exposure area has been increased by the exposure apparatus, and printing has been performed to increase the exposure area of the LSI chip itself in one exposure, or a plurality of LSI chips have been exposed in one exposure. Is being burned. For this reason, it is desired to position the entire exposure region, which is increasing in size or the like, more accurately and reliably at the focal position (within the depth of focus) of the projection optical system.

However, in recent semiconductor device manufacturing and the like, since many complicated structures are stacked on a wafer and manufactured, the flatness of an exposed surface on the wafer tends to be deteriorated. For this reason, a technique has been used in which the state of unevenness in a shot area of a wafer is measured, and an average surface of the shot area is adjusted to an image plane formed by a projection optical system in consideration of the measurement result. For example, in Japanese Patent Application Laid-Open No. 2-198130, the position of the wafer in the optical axis direction of the projection optical system is fixed, and the wafer is moved in the optical axis direction. The height position of the projection optical system in the optical axis direction is measured. Then, by calculating the average value of the height positions at the plurality of measurement points, a correction value of the focal position caused by a difference in the structure and arrangement of the pattern in the shot area (hereinafter, appropriately referred to as an offset value). Is disclosed.

[0007]

As described above, in the conventional focus position detecting device, the height positions measured at a plurality of specific measurement points in a predetermined shot area are averaged, so that the focus position is detected. The optimum focus position was determined by determining the offset position. However, actually, the state of the unevenness of the exposure surface of each shot region varies depending on the process structure (pattern arrangement, process step, etc.), and simply averaging the height positions at a plurality of measurement points will not be sufficient. It has been difficult to match each shot area to the imaging plane of the projection optical system in an optimal state.

That is, as shown in FIG. 3, when any one of a plurality of measurement points provided in a shot area is located at a step portion caused by a process structure, a measurement value at the measurement point is obtained. However, when averaging is used, the desired averaging is not performed, and the accuracy of the offset value of the focal position in the shot area deteriorates. here,
More specifically, at a measurement point located at a step portion, an upper portion of the step (hereinafter, referred to as an upper portion of the step) and a lower portion of the step (hereinafter, referred to as a lower portion of the step) within the same measurement point region.
And exists. For this reason, for example, in a method of projecting a slit image to a measurement point and generating a detection signal corresponding to the amount of lateral displacement of the slit image to detect the height position, the amount of lateral displacement of the slit image is Unlike the lower part, the height position is detected as a value corresponding to the average amount of the lateral shift amount. That is,
The height position at the measurement point located at the step is detected as being intermediate between the upper part of the step and the lower part of the step. Therefore, when the correction value of the focus position is obtained, if the measurement point located at the step is included, the correction value of the theoretical focus position and the correction of the focus position based on the measurement values actually measured at a plurality of measurement points Therefore, it is impossible to detect the optimum focus position. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to detect an optimum focus position and enable highly accurate exposure.

[0009]

According to a first aspect of the present invention, there is provided a focus position detecting apparatus, wherein a height of a substrate surface on which a mask pattern is transferred via a projection optical system in an optical axis direction of the projection optical system is set. In the focus position detection device for detecting the height position, a detection unit having a plurality of measurement points for detecting the height position, before and after moving the substrate and each of the measurement points relatively a predetermined minute distance An arithmetic unit for comparing and calculating the detection results of the detection unit, and a selection unit for selecting the plurality of measurement points based on the result of the arithmetic unit are provided. In the second invention (claim 2), regarding the first invention,
A stage for holding the substrate, and a driving unit for driving the stage in XY directions substantially orthogonal to the optical axis direction, wherein the driving unit drives the stage by a predetermined minute distance to And each of the measurement points is relatively moved a small distance. In a third invention (claim 3), the driving section in the second invention is configured to move the stage in the X direction and / or the Y direction.

In a fourth aspect of the present invention (claim 4), in any one of the first aspect to the third aspect, further comprising a moving means for moving each position of the measurement points on the substrate. Is configured to relatively move the substrate and each of the measurement points by a minute distance by moving the position of the measurement point by a predetermined minute distance. In a fifth invention (claim 5), the arithmetic unit according to the first invention is configured such that a difference between the detection result before and after the stage moves by a predetermined minute distance is obtained for each of the plurality of measurement points. Is obtained.

In a sixth aspect (claim 6), the selection means in the fifth aspect is configured to select a measurement point at which the value of the difference obtained by the arithmetic section does not exceed a predetermined threshold. In a seventh invention (claim 7), the detection unit according to the first invention is arranged such that light of a predetermined wavelength is transmitted to a plurality of measurement points in the projection field on the substrate with respect to an optical axis of the projection optical system. A projection optical system for projecting an image of a pattern for focus detection from an oblique direction, and condensing reflected light from the plurality of measurement points to re-image an image of the focus detection pattern on the plurality of measurement points. And a plurality of photoelectric detecting means for generating a detection signal corresponding to the lateral shift amount of each of the plurality of images re-formed by the light receiving optical system. According to an eighth aspect of the present invention, in the focus position detecting method for detecting a height position of the projection optical system in the optical axis direction on a substrate surface onto which a mask pattern is transferred via a projection optical system, A first detection step of detecting the height position at each of the plurality of measurement points, and after the first detection step, relatively moving the substrate and each of the plurality of measurement points by a predetermined minute distance Performing the step, a second detection step of detecting the height position at each of the plurality of measurement points after moving by the minute distance, and a height position detected by the first detection step and the second detection step And a step of selecting the measurement point based on a result of the calculation. Ninth
In the invention (claim 9), the step of performing the calculation in the eighth invention is configured to obtain a difference between the height positions detected by the first detection step and the second detection step. In a tenth aspect (claim 10), the step of selecting the measurement point in the eighth or ninth aspect is configured to select a measurement point whose height difference does not exceed a predetermined threshold.

[0012]

FIG. 1 is a diagram showing a schematic configuration of an oblique incidence type focal position detecting apparatus according to an embodiment of the present invention. Referring to FIG. 1, an embodiment of the present invention will be described below. Will be described. The focus position detecting device (hereinafter, appropriately referred to as an AF device) shown in FIG. 1 is a multipoint AF device. The multi-point AF device is provided with measurement points for measuring the height position or defocus of the wafer W in the optical axis direction of the projection optical system PL at a plurality of locations in the projection field of view of the projection lens PL. .

In FIG. 1, a non-photosensitive illumination light IL irradiates a slit plate 1 with respect to a resist applied on a wafer W. The light passing through the slit of the slit plate 1 irradiates the wafer W obliquely via the lens system 2, the mirror 3, the aperture 4, the projection objective lens 5, and the mirror 6. At this time, if the surface of the wafer W is on the best image forming plane, the image of the slit of the slit plate 1 is changed to the lens system 2 and the objective lens 5.
Thereby, an image is formed on the surface of the wafer W. The angle between the optical axis of the objective lens 5 and the wafer surface is set to about 5 to 12 degrees.

The light fluxes of the plurality of slit images reflected by the wafer W are passed through a mirror 7, a light receiving objective lens 8, a lens system 9, a vibration mirror 10, and a parallel plate (plane parallel) 12 to receive a light receiving slit plate. 14 is re-imaged. The vibrating mirror 10 minutely vibrates a slit image formed on the light receiving slit plate 14 in a direction orthogonal to the longitudinal direction. The parallel plate 12 shifts the relative relationship between the slit on the slit plate 14 and the center of vibration of the reflected slit image from the wafer W in a direction orthogonal to the slit longitudinal direction. The oscillating mirror 10 is oscillated by a mirror driving unit (M-DRV) 11 driven by a driving signal from an oscillator (OSC) 16.

As described above, when the slit image vibrates on the light receiving slit plate 14, the light beam transmitted through the slit of the slit plate 14 is received by the sensor 15. This sensor 15 has a plurality of slits (14A1
To 14A25) are formed by a plurality of light receiving elements (photoelectric conversion elements) provided corresponding to each of them. That is, in the present embodiment, as shown in FIG. 3, since 5 × 5 25 measurement points (slit images) are provided, the sensor 15 has 25 light receiving elements (15A1 to 15A1).
15A25). Here, the light receiving element uses a silicon photodiode or a phototransistor. FIG. 6 shows the slit plate 14 for light reception.
1 illustrates the arrangement of one slit (14A1) and the corresponding light receiving element (15A1). The selector circuit 13 in FIG. 1 selects a signal (hereinafter, referred to as a focus signal) related to a height position from a sensor 15 composed of 25 light receiving elements, and a synchronous detection circuit (PSD) 17.
To enter. FIG. 2 is a block diagram showing a processing circuit of the focus detection system according to the present embodiment. As shown in FIG. 2, the selector circuit 13 is illustrated so that focus signals from five measurement points can be selected. This PSD 17 has OS
C. An AC signal having the same phase as that of the drive signal from 16 is input, and synchronous rectification is performed based on the phase of the AC signal.

At this time, the PSD 17 is connected to the selector circuit 13.
A plurality of detection circuits (17A to 17E) for individually and synchronously detecting the output signals at the five measurement points selected from the sensors 15 by using the detection outputs FS (F
Sa to FSe) are output to the main control unit (MCU) 30. The detection output signal FS is called a so-called S-curve signal, and the center of the slit of the light receiving slit plate 14 and the wafer W
When the center of vibration of the reflected slit image from the center is coincident, the level becomes zero. When the wafer W is displaced upward from that state, the level is positive. When the wafer W is displaced downward, the level is negative. Become a level. Therefore, the detection output signal FS
Is detected as a focal point.

FIG. 3 shows a shot area SA of the wafer W.
The measurement points distributed above are illustrated, and each of the measurement points is a slit image of light transmitted through the slit plate 1 and is a direction inclined on the wafer W by 45 degrees with respect to the X direction or the Y direction. Is formed. In addition,
In the present embodiment, an example will be described in which one detection row having five measurement points in the Y direction is arranged in five rows in the X direction as shown in FIG.

It is known that in the shot area SA, the amount of change in the state of irregularities (process structure) increases each time a device manufacturing process is performed, and the areas PA1 and P2 in FIG.
A2 indicates an area having a different process structure. Then, the regions PA1 and PA2 having different process structures
A step occurs at the boundary portion with 2. In this case, when a measurement point having a predetermined area is located at this step portion, the state of the step (irregularity) greatly differs even within the same measurement point region. FIG. 4A shows this state.

Here, focusing on the measurement point SP located at the step portion in FIG. 3, as shown in FIG. 4A, the slit image at the measurement point SP, ie, in the measurement area, There are different height surfaces at the upper part of the step and at the lower part of the step. Therefore, the focus signal at the measurement point SP located at the step portion is a signal representing an intermediate height between the height of the area PA1 and the height of the area PA2 as described above. This is because the sensor 15 cannot recognize whether the reflected light passing through the slit plate 14 is the reflected light from the area PA1 or the area PA2.

In FIG. 6, the slit 14A1 of the slit plate 14 held by the holding frame 14B is
The light receiving element 15A1 provided in the contact is closely attached in parallel with the longitudinal direction. Accordingly, the vibration center of the reflected light from the area PA1 and the vibration center of the reflected light from the area PA2 pass through the light receiving slit plate 14A1 shown in FIG. 6 in a state different from each other. Light will be received simultaneously. For this reason, the sensor 15A1
The height position at P is detected as the average value of the area PA1 and the area PA2.

In FIG. 4, the length L when projecting the slit image in the Y direction is about 2-3 mm, and the height h of the step is about 1-2 μm. As described above, when detecting the height position of the wafer by averaging the focus signals at a plurality of measurement points in the shot area, the height position thus obtained as the average value of the upper step and the lower step is calculated as follows. It is not preferable to use it for the average calculation for obtaining the height position of the wafer. Therefore, it is necessary to remove the focus signal at the measurement point that has an adverse effect, that is, the focus signal at the measurement point located at the step portion in the average calculation.
Details of the detection of the measurement point located at the step and the non-selection of the focus signal at the detected measurement point will be described later.

Incidentally, a wafer W as a photosensitive substrate is
It is held on a Z leveling stage 20. Also, Z
The leveling stage 20 is provided on the XY stage 21. The XY stage 21 is driven in a two-dimensional plane (within the XY plane in FIG. 1) by a drive unit 22 (including a motor and its control circuit) under a command from the MCU 30. The driving of the driving unit 22 with respect to the XY stage 21 makes it possible to position the wafer W at a predetermined position or to sequentially expose a plurality of shot areas provided on the wafer W.

The drive unit 18 includes a Z leveling stage 20
Is driven in the optical axis direction (Z-axis direction) of the projection lens PL by driving the Z driving mechanism (not shown) provided on the XY stage by the driving unit 18. The Z drive mechanism includes at least three piezo elements that can expand and contract in the Z-axis direction.
The drive unit 18 drives the Z-leveling stage 22 in the Z-axis direction by expanding and contracting the piezo element under the instruction of 0.

The Z-leveling stage 22 can be tilted with respect to a plane perpendicular to the optical axis direction of the projection lens PL by driving the drive unit 22. Thereby, the surface of the wafer W can be inclined at a desired angle. Next, the operation of the focus position detecting device of the present embodiment configured as described above will be described with reference to FIG. The focus position detection method using a plurality of measurement points is substantially the same as, for example, the method disclosed in Japanese Patent Application Laid-Open No. 5-275313 by the present applicant.

First, the MCU 30 controls the X through the drive unit 22.
By driving the Y stage 21, the shot area SA in which the positional shift in the optical axis direction is to be detected is positioned at a predetermined position that falls within the projection area of the projection lens PL. (Step 100). When the positioning of the shot area SA is completed, the height positions Z1 to Z5 of the wafer W are measured at each of the five points selected by the selector circuit 13 out of a total of 25 measurement points of 5 × 5 ( Step 10
1). Note that the selected five measurement points are MCU3
It can be set arbitrarily electrically under the command of 0, for example, SPa, SPb, SPc, SPd, SPe shown in FIG.
Select The height positions Z1 to Z5 measured in step 101 are stored in a memory in the MCU 30.
Now, when the height positions Z1 to Z5 at each measurement point are measured and stored in the memory in step 101, the MCU
30 outputs a command to the driving unit 22 to move the XY stage 21 by a very small distance (a very small pitch). Drive unit 22
Performs a drive to move the XY stage 21 by a small distance in the X direction and the Y direction under the instruction of the MCU 30 (step 102). When the direction of the step is known in advance, the direction in which the XY stage 21 moves may be any one of X and Y to increase the throughput. The direction in which the XY stage 21 moves may be an oblique direction (XY simultaneous movement direction). This allows
Two measurement operations can be performed once in the X and Y directions, and the throughput can be relatively improved. This is also effective when detecting a measurement point located at a step when the step due to the process structure exists in a direction oblique to the X and Y directions. Further, the MCU 30 may control the drive unit 22 to move the XY stage 21 in the + direction and the − direction in each of the X direction and the Y direction in order to increase the detection accuracy. Here, the minute distance by which the drive unit 22 moves the XY stage 21 will be described with reference to FIG. FIG.
(A) is a cross-sectional view of the shot area SA at the measurement point SP, which is a state before the XY stage 21 moves a minute distance. The drive unit 22 moves the XY stage 21 by a small distance ΔP from the state of FIG. FIG. 4B shows the XY stage 21.
FIG. 7 is a diagram showing a state after the user has moved a distance ΔP. This minute distance ΔP is, for example, 1 of the length L when projecting the slit image at one measurement point in the X direction or the Y direction.
/ 2.

Next, in the shot area SA moved by the minute distance ΔP, the same measurement points (SPa to SPe) as those selected by the selector circuit in step 101 are used.
Are measured (step 103). The memory inside the MCU 30 similarly stores Z′1 to Z′5 as measured values.

Next, by comparing the measured values before and after the movement of the XY stage 21 in step 102, a measurement point located at the step is detected (step 1).
05). Hereinafter, a method of detecting the measurement point located at the step will be described in detail. The MCU 30 has a height position Z1 before movement.
Z5 and height positions Z'1 to Z'5 are read from the memory,
The measured values before and after the movement are compared for each measurement point. This comparison is performed, for example, by obtaining a difference. Therefore, in this case, the MCU 30 calculates ΔZ1 = Z1-
Z1 ′, ΔZ2 = Z2-Z2 ′, ΔZ3 = Z3-Z
3 ′, ΔZ4 = Z4-Z4 ′, ΔZ5 = Z5-Z5 ′. Then, the MCU 30 calculates the difference value (Δ
If one of Z1 to ΔZ5) is equal to or greater than a predetermined threshold value, it is detected that the measurement point is a measurement point located at the step. This is because the measured value of the height position greatly changes before and after the measurement point located at the step portion moves by the minute distance ΔP.

More specifically, at a measurement point located at a step before moving a minute distance,
For the height position, an intermediate value between the upper part of the step and the lower part of the step is measured. Then, at this measurement point after the movement of the minute distance, the height position under the step is measured (FIG. 4B).
Therefore, the change in the measured height position is detected as a difference between the height positions before and after the movement. Conversely, for a measurement point that is not located at the step, the measured height position does not change before and after the movement of the minute distance. The present invention pays attention to this point, and moves the XY stage 21 to the minute distance ΔP
By determining the difference between the measured values of the height positions before and after the movement, it is detected whether or not each of the measurement points is located at the step.

When the measurement point located at the step portion is detected in this way, the MCU 30 averages the measurement values at the measurement points not located at the step portion without using the measurement value at the measurement point (step 30). 105). That is, the MCU 30 non-selects the measurement point located at the step portion and selects the measurement point not located at the step portion. The value averaged using the measurement values at the selected measurement point is
The height position is optimal for exposing a shot region having a different process structure and having irregularities. MCU3
0 is the Z leveling stage 20 via the drive unit 18 based on the optimal height position determined in step 105.
Is driven in the Z direction. Thus, the focus position adjusting operation before the start of the exposure is completed (step 106).

In the case of the present invention, the XY stage 21 is moved by a small distance to detect a measurement point located at a step before the focus position adjusting operation. Therefore, when transferring (exposure) a reticle as a mask on which a circuit pattern or the like is formed to a wafer coated with a photosensitive material, it is necessary to perform relative alignment (alignment) between the reticle and the wafer. Therefore, the exposure operation is performed after the alignment between the reticle and the wafer is completed.

As described above, in this embodiment, when the position (height position) of the surface of the wafer in the optical axis direction is obtained by using a plurality of measurement points, the XY stage on which the wafer is mounted is slightly moved. The measured values before and after the minute movement are compared. When a measurement point located at the step is detected by comparing the measurement values, the measurement at the measurement point located at the step is used non-selectively. This makes it possible to detect the optimal height position of the shot area to be exposed.

In the present embodiment, the measurement point located at the step is detected by calculating the difference between the measurement points before and after the minute movement. However, the present invention is not limited to this. The present invention is also applicable to various comparison operations such as sum or product of measurement points. Further, in the present embodiment, the focus position detecting apparatus and method using a plurality of measurement points have been described as an example, but the present invention can be applied even when there is only one measurement point for focus position detection.
That is, when one measurement point existing in the shot area is located at the step portion, it is possible to detect whether the measurement point is located at the step portion by the above-described method. When it is detected that this measurement point is located at the step portion, for example, the measurement position may be changed to a position not located at the step portion in the same shot area. As described above, the detection of the measurement point located at the step portion and the non-selection of the detected measurement point are generally performed as preprocessing before the wafer exposure operation as described above. However, the present invention is not limited to this,
For example, when a plurality of shot areas are provided on a wafer, it may be performed immediately before exposure to all or any of the plurality of shot areas. Next, another embodiment of the present invention will be described. That is, in the above-described embodiment, the relative movement between the wafer W as the substrate and the plurality of measurement points is performed by moving the XY stage 21 by a very small distance. However,
In this other embodiment, the relative movement between the wafer W and the plurality of measurement points is performed by moving the position of the slit image on the wafer W instead of driving the XY stage 21. Hereinafter, another embodiment will be described with reference to FIG. Note that the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 7 is a schematic configuration diagram of the present embodiment. That is, in this embodiment, a parallel flat plate 50 is provided between the lens system 2 and the light projecting lens 5 in FIG. The parallel flat plate 50 rotates around an axis in a direction perpendicular to the paper surface of FIG. By the rotation of the parallel plate 50,
The illumination light IL can be translated. The manner in which the optical axis of the illumination light moves in parallel is shown by the dotted line in FIG. When the parallel-moved illumination light IL is irradiated on the wafer W via the reflection of the mirror 6, the irradiated position on the wafer W is similarly moved. The operation of the present embodiment based on the above configuration will be described below. In the present embodiment, step 101 for measuring the height position (Z1 to Z5) described above.
Thereafter, the parallel plate 50 is rotationally driven. Thereby, the positions of the plurality of measurement points on the wafer W move. This moving distance is a minute distance of ΔP similarly to the above-described distance (FIG. 7). When the relative position between each of the plurality of measurement points and the substrate is moved by a very small distance by rotating the parallel plate 50, the height positions Z′1 to Z′1 to
Measure Z'5. Steps after step 103 are the same as steps 104 to 106 described above.

As described above, according to the present embodiment, the relative position between each of the plurality of measurement points on the wafer W and the substrate can be moved by a small distance by rotating the parallel plate 50. Since this drives only the parallel flat plate lighter than the XY stage 21, the control speed can be improved and power consumption can be reduced.

[0034]

As described above, according to the present invention, it is possible to eliminate the adverse effect on the focus position detection by the measurement point located at the step. Therefore, it is possible to detect an optimum focus position even for a shot region having regions having different process structures.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an oblique incidence type focus position detecting apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a processing circuit of a focus detection system according to the embodiment of the present invention.

FIG. 3 is a diagram showing measurement points distributed on a shot area of a wafer.

FIG. 4 is a cross-sectional view of a portion where a step occurs in a shot region.

FIG. 5 is a flowchart illustrating an operation of the focus position detection device according to the embodiment of the present invention.

FIG. 6 is a diagram showing an arrangement of a slit plate 14 for light reception and a sensor 15;

FIG. 7 is a schematic configuration diagram showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Slit plate 2, 9 Lens system 3, 6 Mirror 4 Aperture 5 Projection objective lens 10 Vibration mirror 12 Parallel plate 13 Selector circuit 14 Light receiving slit plate 15 Light receiving element 16 Oscillator 17 Synchronous detection circuit 20 Z leveling stage 30 Main control Unit 50 Parallel plate PL Projection lens W Wafer

Claims (10)

[Claims] 1. A focus position detecting device for detecting a height position in a direction of an optical axis of the projection optical system on a substrate surface on which a mask pattern is transferred via a projection optical system, wherein a plurality of the height positions are detected. A detection unit having measurement points of: a calculation unit for comparing and calculating detection results of the detection unit before and after relatively moving the substrate and each of the measurement points by a predetermined minute distance; a result of the calculation unit And a selecting unit for selecting the plurality of measurement points based on the focus position. 2. The focus position detecting device according to claim 1, further comprising: a stage for holding the substrate; and a drive unit for driving the stage in an XY direction substantially orthogonal to the optical axis direction. A focus position detecting device, wherein the driving unit moves the substrate and each of the measurement points relatively by a minute distance by driving the stage by a predetermined minute distance. 3. The driving unit according to claim 2, wherein the driving unit moves the stage in an X direction and / or a Y direction.
The focus position detecting device according to any one of the preceding claims. 4. The focus position detecting device according to claim 1, further comprising a moving unit configured to move each position of the measurement point on the substrate. Is a focus position detecting apparatus, wherein the substrate and each of the measurement points are relatively moved by a minute distance by moving the position of the measurement point by a predetermined minute distance. 5. The computer according to claim 1, wherein the calculation unit calculates a difference between the detection result before and after the stage has moved by a predetermined minute distance for each of the plurality of measurement points. 2. The focus position detecting device according to claim 1. 6. The focus position detecting device according to claim 5, wherein said selecting means selects a measurement point at which the value of the difference obtained by said calculation section does not exceed a predetermined threshold value. 7. The pattern detecting device according to claim 7, wherein the detecting unit emits light having a predetermined wavelength to a plurality of measurement points in the projection field of view on the substrate at an oblique angle with respect to an optical axis of the projection optical system. A projection optical system for projecting an image, a light receiving optical system for condensing reflected light from the plurality of measurement points and re-forming an image of a focus detection pattern on the plurality of measurement points, and a light receiving optical system 2. A focus position detecting apparatus according to claim 1, further comprising: a plurality of photoelectric detecting means for generating detection signals corresponding to the lateral shift amounts of the plurality of images re-formed by the method. 8. A focus position detecting method for detecting a height position in a direction of an optical axis of the projection optical system on a substrate surface onto which a mask pattern is transferred via a projection optical system, wherein a plurality of measurement points on the substrate are provided. A first detection step of detecting the height position at each of the following steps: after the first detection step, a step of relatively moving the substrate and each of the plurality of measurement points by a predetermined minute distance; After moving by a minute distance, a second detection step of detecting the height position at each of the plurality of measurement points; and calculating based on the height positions detected by the first detection step and the second detection step Performing a focus position detection based on the result of the calculation. 9. The focus position detecting method according to claim 8, wherein the step of performing the calculation obtains a difference between the height positions detected by the first detecting step and the second detecting step. 10. The step of selecting a measurement point,
10. The focus position detecting method according to claim 8, wherein a measurement point at which the difference between the height positions does not exceed a predetermined threshold value is selected.