JP2006078229A - Position detection method and its device, alignment measuring method and its device, and exposure method and its device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position detection method and a position detection device capable of detecting consistency of a position detection result by a simple processing, and at least reducing a probability of continuation of a subsequent processing on an improper focusing position, concerning the position detection method and the device of a grazing incidence system. <P>SOLUTION: In this position detection method, two detection lights are allowed to enter the surface to be measured of a position detection object obliquely respectively, and two reflected lights reflected by the surface to be measured are received respectively, and the position in the vertical direction to the surface to be measured, on the surface to be measured is detected based on the interval between each light receiving position on the light receiving surface of the two reflected lights. It is determined whether a desired detection result detected based on the interval between each light receiving position of the two reflected lights is proper or not, based on two position detection results of the surface to be measured detected individually respectively based on each light receiving position of each of the two reflected lights. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a position that detects the position of a surface to be exposed such as a substrate suitable for application to an exposure apparatus when manufacturing an electronic device such as a semiconductor element based on the relative position of reflected light of two obliquely incident lights. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection method and apparatus, an alignment measurement method and apparatus using the position detection method, and an exposure method and apparatus for determining the position of a substrate to be exposed by the alignment measurement method.

When manufacturing an electronic device such as a semiconductor device, a liquid crystal display device, an imaging device such as a CCD, a plasma display device, or a thin film magnetic head (hereinafter collectively referred to as an electronic device), a photomask or reticle is used using an exposure apparatus An image of a fine pattern formed (hereinafter collectively referred to as a reticle) is projected and exposed onto a substrate such as a semiconductor wafer or a glass plate coated with a photosensitive agent such as a photoresist.
There are various types of exposure apparatuses used at this time, but step-and-repeat projection exposure apparatuses (steppers) and step-and-scan projection exposure apparatuses (scanning steppers) are widely used. ing. After the relative alignment between the reticle and the photosensitive substrate, the stepper sequentially exposes the pattern formed on the reticle to a plurality of shot areas set on the photosensitive substrate while stepping the photosensitive substrate ( This is an exposure apparatus for transferring.

Usually, a plurality of patterns are superimposed and exposed on each shot area on a wafer to manufacture a device. In order to reduce the error in this superposition, this type of exposure apparatus is equipped with a position detection device (alignment detection device) for measuring the position of the pattern exposed on the previous layer. This type of position detection apparatus includes a focus detection apparatus for measuring an alignment mark on the wafer in an optimal focus state. For example, as this type of focus apparatus, a so-called pupil division type position detection system is provided. It has been known. In the pupil division method, for example, the object surface (photosensitive substrate surface in the case of an exposure apparatus) is illuminated with a slit-shaped light beam, and the light beam from the illuminated object surface is near the pupil plane of the objective optical system or the pupil conjugate plane. Divide the pupil with. Then, based on the position information of the pupil-divided light beam, the relative position of the object plane with respect to the focal position of the objective optical system (in the case of an exposure apparatus, the relative position of the photosensitive substrate surface with respect to the imaging plane of the projection optical system) It detects (for example, refer patent document 1).
JP-A-8-167550

In such a grazing incidence position detection device, for example, even if the reflectance of the reflecting surface is difficult to measure, or even if the measurement is not properly performed due to a change in the measurement mechanism over time, If a measurement result within a measurement stroke in which the focus position is assumed in advance is obtained based on the relative positional relationship between the reflected lights of the two obliquely incident lights, the value is used for focusing. That is, the focus adjustment is performed by believing the detection result of the focus position by this oblique incidence method as it is. However, as a result, there is a possibility that pattern position detection or the like may be performed when the focus state is not appropriate.
If the focus state is inadequate, the position of the alignment mark or the like cannot be detected properly, and an appropriate pattern cannot be transferred onto the substrate at an appropriate position with an appropriate line width. Improvement is desired.

The present invention has been made in view of such problems, and its purpose is to detect the consistency of the position detection result by simple processing in the position detection method and apparatus of the oblique incidence method, and at least It is an object of the present invention to provide a position detection method and a position detection apparatus that can reduce the possibility of continuing the subsequent processing at an inappropriate focus position.
Another object of the present invention is to provide an alignment measurement method and an alignment measurement apparatus that can avoid alignment measurement in an inappropriate focus state.
Another object of the present invention is to provide an exposure method and an exposure apparatus capable of performing alignment in an inappropriate focus state and further avoiding exposure processing.

  In order to solve the above-described problem, a position detection method according to the present invention makes two detection lights incident obliquely on a measurement target surface that is a position detection target, and two reflected lights reflected by the measurement target surface. In the position detection method of detecting each position of the surface to be measured in a direction perpendicular to the surface to be measured based on the interval between the light receiving positions on the light receiving surface of the two reflected lights. Whether the desired detection result detected based on the interval between the light receiving positions of the two reflected lights is appropriate or not is determined individually based on the light receiving positions of the two reflected lights. A detection result confirming step for determining based on the two position detection results of the surface to be measured (claim 1);

  Further, the position detection device according to the present invention causes two detection lights to enter the measurement target surface to be position-detected obliquely, receives the two reflected lights reflected by the measurement target surface, and receives the two reflections. A position detection device for detecting a position of the measurement target surface in a direction perpendicular to the measurement target surface based on an interval between the respective light reception positions on the light reception surface, wherein each light reception of the two reflected lights Whether or not the desired detection result detected based on the interval between the positions is appropriate is determined based on the two measured surfaces individually detected based on the light receiving positions of the two reflected lights. It has a detection result confirmation means for judging based on the position detection result (claim 11).

According to the present invention, in the position detection method and apparatus of the oblique incidence method, it is possible to detect the consistency of the position detection result by a simple process, and to continue the subsequent process at least at an inappropriate focus position. It is possible to provide a position detection method and a position detection apparatus that can reduce the amount of the noise.
In addition, it is possible to provide an alignment measurement method and an alignment measurement apparatus that can avoid alignment measurement in an inappropriate focus state.
In addition, it is possible to provide an exposure method and an exposure apparatus that can perform alignment in a state where the focus state is inappropriate and can avoid performing an exposure process.

An exposure apparatus according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a drawing schematically showing a configuration of the exposure apparatus of the present embodiment.
The exposure apparatus shown in FIG. 1 has an exposure illumination system IL for uniformly illuminating a reticle R as a mask with predetermined exposure light. The reticle R is supported substantially parallel to the XY plane on the reticle stage RS, and a circuit pattern to be transferred is formed in the pattern area PA.
The light illuminated by the exposure illumination system IL and transmitted through the reticle R reaches the wafer W via the projection optical system PL, and a pattern image of the reticle R is formed on the wafer W. The wafer W is supported substantially parallel to the XY plane on the Z stage ZS via the wafer holder WH.

The Z stage ZS is supported on the XY stage XY, and is configured to be driven along the optical axis of the projection optical system PL by the stage control system SC.
The XY stage XY is also configured to be driven two-dimensionally in the XY plane perpendicular to the optical axis of the projection optical system PL by the stage control system SC. The stage control system SC is configured to be controlled by the main control system MC.

  In the exposure apparatus having such a configuration, it is necessary to set the exposure surface of the wafer W with respect to the imaging surface of the projection optical system PL prior to the projection exposure. Therefore, the exposure apparatus is equipped with a position detection device PD for detecting the relative position of the wafer W along the optical axis with respect to the imaging plane of the projection optical system PL.

FIG. 2 is a diagram schematically showing the overall configuration of the position detection device PD shown in FIG.
The position detection device PD includes, for example, a first light source (not shown) in which a wavelength selection filter is provided in a halogen lamp, and illumination light (for example, a wavelength of 530 nm to 800 nm) supplied from the first light source is a relay lens (not shown). It enters into a pair of light guides 1a and 1b like an optical fiber through a system.
The illumination light propagating through the inside of the light guides 1a and 1b is emitted from its exit end and then enters the illumination optical system 2 of the alignment autofocus (ALG-AF) optical system. The schematic configuration of the illumination optical system 2 is shown in FIG. In FIG. 3A, the illumination system for guiding the light (first detection light) emitted from the light guide 1a shown on the left side onto the wafer, and the light (second detection light) emitted from the light guide 1b. The illumination system guided onto the wafer is the same except that the configuration is symmetrical.

The light beams emitted from the light guides 1a and 1b and passed through the lens systems 20a and 20b illuminate the illumination slits 22a and 22b, respectively.
The illumination slits 22a and 22b are arranged at or near the position optically conjugate with the surface of the wafer W, and have a line and space pattern (a pair of thick patterns) having a pitch direction along the X direction as shown in FIG. A plurality of openings corresponding to a line pattern and five thin line patterns sandwiched therebetween.

  The light that has passed through the illumination slit 22a enters the second objective lens 13 via the lens system 24a, the prisms 26a and 28a, and the half mirror 3 as a first detection light beam. On the other hand, the light beam that has passed through the illumination slit 22b is incident on the second objective lens 13 via the lens system 24b, the prisms 26b and 28b, and the half mirror 3 as the second detection light beam.

The light beam that has passed through the second objective lens 13 is reflected by the mirror 14, passes through the half prism 15, and then enters the first objective lens 16. The light beam incident on the first group of the first objective lens 16 is reflected by the mirror 17 disposed in the optical path, and then the surface of the wafer W (surface to be measured) through the second group of the first objective lens 16. , Exposure surface).
At this time, the first detection light beam and the second detection light beam are obliquely incident with respect to the normal line of the surface of the wafer W from an oblique direction, and as shown in FIG. In 81, a slit pattern image having a form as shown in FIG. 5B is formed. A circle 82 indicated by a broken line in FIG. 5A corresponds to the visual field of the imaging optical systems 13 and 16. Further, as shown in FIG. 5B, each slit image via the slits 22a and 22b is projected on the wafer with an inclination of about 30 degrees with respect to the street line.

  As described above, the first detection light beam and the second detection light beam form a pattern corresponding to the opening pattern of the illumination slits 68b and 68c as shown in FIG. At this time, in the focus state in which the focal position of the first objective lens 16 and the surface of the wafer W coincide with each other, the two line and space patterns are set to overlap as shown in FIG. ing.

  The reflected light from the wafer W illuminated by the pair of detection light beams is a first objective lens 16, a mirror 17, a half prism 15, a mirror 14, a second objective lens 13, and half mirrors 3 and 4 disposed in the optical path. Then, the light enters the detection optical system (light receiving optical system) 5 of the ALG-AF optical system. The schematic structure of the light receiving optical system 3 is shown in FIG. In FIG. 3B, the first detection light beam emitted from the light guide 1a is reflected on the wafer W, and then the optical system (prisms 310a and 320a and lens system 330a shown on the right side in FIG. 3B). , And reaches the aperture stop plate via the prisms 340a and 350a). The second detection light beam emitted from one light guide 1b reaches the aperture stop plate 6 via the optical system (310b to 350b) illustrated on the left side in FIG. After that, each light beam passes through each aperture 6a, 6b (see FIG. 6C) of the diaphragm 6, and then, as shown in FIG. 6A, X on the imaging surface 7a of the one-dimensional image sensor 7. Two pattern images 73a and 73b are formed at positions spaced apart along the direction. Here, as shown in FIG. 6B, the first pattern image formed by the first detection light beam reflected by the surface of the wafer W and the second pattern image formed by the second detection light beam are shown in FIG. This corresponds to the pattern of the illumination slits 22a and 22b.

The one-dimensional imaging device 7 photoelectrically detects two pattern images formed on the imaging surface 7 a and supplies a detection signal to the signal processing system 26. FIG. 7 shows an example of a signal tooth system of a pair of pattern images measured by the image sensor 7. In the signal processing system 26, as will be described later, the position of one specific line portion in the first pattern image, the position of one specific line portion in the second pattern image, and the specific line portion of these two patterns The center-to-center distance is measured, and a relative positional deviation amount in the height direction (Z direction) of the surface of the wafer W with respect to the focal position of the first objective lens 16 is detected based on the measured center-to-center distance.
The position of the line portion of the first pattern image, the position of the line portion of the second pattern image detected by the signal processing system 26, and the relative positional deviation amount between the line portion of the first pattern image and the line portion of the second pattern image. This information is supplied to the main control system MC.

In the main control system MC, the position of the line portion of the first pattern image, the position of the line portion of the second pattern image supplied from the signal processing system 26, and the line portion of the first pattern image and the line of the second pattern image First, it is determined whether or not the detection result is a valid result based on the information on the relative positional deviation amount of the part. If it is determined that the detection result is an appropriate result, a command for driving the Z stage ZS along the optical axis AX by the detected relative displacement amount is supplied to the stage control system SC.
In this way, the exposure surface of the wafer W is set at the focal position of the first objective lens 16 by the action of the stage control system SC that operates based on a command from the main control system MC.

Further, the position detection device PD includes an FIA system position detection unit for detecting the X-direction position and the Y-direction position of the wafer mark formed on the wafer.
The FIA system position detection unit includes, for example, a second light source (not shown) in which a wavelength selection filter is added to a halogen lamp (for example, generates broadband light having a wavelength of 530 nm to 800 nm) and infrared light such as an LED (for example, wavelength 870 nm). And a third light source for supplying light.

  Light from the second light source and the third light source enters a light guide 31 such as an optical fiber via a relay lens or the like. The light propagating through the light guide 31 is emitted from the exit end thereof, reflected by the half prism 15 via the relay lens 34, and then incident on the indicator plate 35 via the first objective lens 16. . The index plate 35 is a parallel flat plate-like optical member made of, for example, quartz glass, and an infrared reflection film is formed on the lower side surface (side surface of the wafer W). The infrared reflecting film reflects infrared light from the third light source and transmits white light (visible light, the above-described broadband light) from the second light source. For example, the infrared reflecting film is formed of a dielectric layer film. ing.

  Therefore, the white light from the second light source passes through the indicator plate 35 and illuminates the wafer mark formed on the wafer W. The reflected light from the illuminated wafer mark is incident on the half prism 15 via the indicator plate 35 and the first objective lens 16. On the other hand, the infrared light from the third light source propagates inside the indicator plate 35, is reflected by the infrared reflecting film, propagates inside the indicator plate 35, and illuminates the indicator mark. Then, the reflected light from the illuminated index mark propagates inside the index plate 35, is reflected by the infrared reflection film, propagates inside the index plate 35, and then passes through the first objective lens 16 to be a half prism. 15 is incident.

  White light and infrared light transmitted through the half prism 15 enter the third objective lens 36 via the mirror 14, the second objective lens 13, and the half mirrors 3 and 4. White light and infrared light that have passed through the third objective lens 36 enter the dichroic mirror 40 via the aperture stop 37, the fourth objective lens 38, and the mirror 39. The dichroic mirror 40 has a characteristic of transmitting infrared light while reflecting white light. Therefore, the white light from the wafer mark is reflected by the dichroic mirror 40 and enters the wafer mark detection CCD 41.

Thus, an image of the wafer mark is formed on the imaging surface of the wafer mark detection CCD 41. An output signal from the wafer mark detection CCD 41 is supplied to the signal processing system 26. On the other hand, infrared light from the index mark passes through the dichroic mirror 40, is reflected by the mirror 42, and then enters the index mark detection CCD 43. An image of the index mark is formed on the imaging surface of the index mark detection CCD 43. An output signal from the index mark detection CCD 3 is supplied to the signal processing system 26.
In FIG. 5, a rectangular region 83 in the center of the circular field 82 of the imaging optical systems 13 and 16 corresponds to the imaging surface of the wafer mark detection CCD 41 and the imaging surface of the index mark detection CCD 43.

  The signal processing system 26 performs signal processing (waveform processing) on the output signal from the wafer mark detection CCD 41 and the output signal from the index mark detection CCD 43, thereby obtaining wafer mark position information based on the index mark. . The wafer mark position information detected by the signal processing system 26 (that is, the position information of the wafer W) is supplied to the main control system MC. In the main control system MC, based on the position information of the wafer W supplied from the signal processing system 26, a command for driving the XY stage XY is supplied to the stage control system SC. Thus, alignment (positioning) between the pattern area PA on the reticle R and each exposure area on the wafer W is performed by the action of the stage control system SC that operates based on a command from the main control system MC.

Next, a method of determining the focus position detection result according to the present invention in such a position detection device PD will be described.
As described above, in the present embodiment, the detection result of the focus position detected based on the relative positional relationship between the detected light beams of the two systems based on the detection positions (absolute positions) of the detected light beams of the two systems. Determine the validity of. Various thresholds can be used as the criterion (determination threshold) for the determination. For example, it is preferable to use a threshold that allows a deviation of the degree of play in measurement reproducibility. Here, “deviation of play” is an allowable value of deviation within about 1 μm (1000 nm) in the Z direction.
A method of determining the focus position detection result in that case will be described.

  The signal shown in FIG. 8 is a diagram showing light reception signals of two lines for detecting the relative positional relationship between the left and right systems of obliquely incident light as shown in FIG. The two convex portions in FIG. 8 indicate left and right system signals, respectively. Here, the left system is a system 310b-7 (FIG. 3B) that receives the second detection light beam emitted from the light guide 1b in FIG. 3A, and the right system is FIG. 3A. ) To detect the second detection light beam emitted from the light guide 1a. In this detection signal, such a signal is obtained when a low reflective surface area in the circuit pattern in the shot area on the wafer enters the left half of the left system, for example.

In FIG. 8, it is assumed that there is no difference between the reference position X2 and the observation position X2 ′ in the right system, and the observation position X1 ′ is obtained as an observation value with respect to the reference position X1 in the left system. Here, the reference positions X1 and X2 refer to a reference surface (for example, a non-mark forming surface on a fiducial mark plate (not shown) provided on the wafer stage) having a uniform brightness in advance (in advance). Then, focus measurement is performed using the above-described ALG-AF system of the position detection device PD, and two sensors on the sensor (CCD 7) obtained based on the measurement signal of the ALG-AF system when the in-focus state is achieved. Each position of the slit pattern image.
At this time, each defocus amount ΔZ calculated from the interval X2′−X1 ′ and the positions X1 ′ and X2 ′ of the left system and the right system is

It becomes. Here, S is a coefficient indicating the relationship between X and ΔZ measured in advance, and S _{X1 ′} S _{X2 ′} is the position on the sensor (CCD 7) of each of the pair of slit pattern images. (In this case, the position in the X direction) and ΔZ are shown, and S _{X1′−X2 ′} shows the relationship between the relative position interval of the pair of slit pattern images on the sensor (CCD7) and ΔZ. is there.
The three ΔZs shown in the above equation (1) should match if there is no measurement error and no measurement trick.
However, suppose that the left and right systems have 3 pixels on the sensor for each reflecting surface position conversion of 3 μm, and 3 pixels on the left and right sensor on the reflecting surface position conversion is 1.5 μm.

The result is obtained. And, from the viewpoint that the set threshold value allows a normal measurement reproducibility specification value and the above-described degree of play, for example, if it is set to be less than 1.5 μm, it is clear from the above calculation result. Any deviation amount exceeds the threshold value, and it is determined that some inconvenience has occurred.
In the present embodiment, the validity of the focus position thus detected is determined.
In addition to the above threshold value, for example, when a multi-line mark image is used, a threshold value corresponding to the missing pitch may be used as a criterion for determination.

Next, a method for inspecting from the inclination of the edge of the signal waveform measured by the ALG-AF system (image sensor 7) will be described.
When determining the suitability of the focus detection result from the inclination of the edge, as shown in FIG. 9, the correspondence between the defocus amount, the edge inclination amount, and the positions on the sensors of the left and right systems is obtained in advance. Specifically, the wafer stage (reference surface) is moved in the Z direction in a state in which the above-described slit image of the alignment AF system is projected onto a reference surface (for example, the above-described FM non-mark forming surface) having a uniform luminance distribution. The line sensor 7 obtains (samples) the measurement signal at each Z position while swinging it. Based on the signal from the sensor 7 at each Z position, the position, defocus amount, and edge inclination amount of the slit pattern image detected by the left and right systems on the sensor 7 are obtained in association with each other. The edge inclination amount indicates the peak value (differential value) of the differential signal obtained by differentiating the measured signal (slit pattern photoelectric signal). In FIG. 9, the edge inclination amount is assumed to be the same for the left and right systems. However, in order to increase the accuracy, it is appropriate to extract the relationship with the edge inclination amount for each of the left and right systems.

When the above information amount (for example, the data in FIG. 9) is obtained with an appropriate number of sampling points, it is performed on the data obtained with the secondary (or higher order) interpolation, and the sensor position and edge inclination amount as shown in FIG. Get relationship (function, polynomial). This obtained relationship becomes a reference for comparison with the measured data.
Then, the edge inclination amounts (measured values) of the left and right systems calculated based on the focus signal (signal of the line sensor 7) obtained by measurement (actual measurement) at the time of focus detection on the actual wafer, and FIG. As shown in FIG. 10, the reference value of the edge tilt amount calculated from the sensor position and the edge tilt amount (relationship reference relationship) as shown in FIG. And the relationship between the edge inclination amount y calculated by the respective functional expressions of the left and right systems and the above-described allowable threshold value) and the difference (the measured value of the edge inclination amount and the reference value) If the difference between the two values exceeds a predetermined threshold value, it is determined that the system is fooled.

Here, a method using the above-described edge inclination amount will be described with a specific example.
When the focus detection of a certain process wafer is performed using the alignment focus detection system (ALG-AF system) configured as described above (when the slit pattern image is detected by the line sensor 7), the slit detected by the left system Assume that the position of the pattern image on the line sensor 7 is 0 [pixel], and the edge inclination amount of the signal waveform corresponding to the slit pattern image is 139.
Now, the above-described allowable threshold is set to 1.0 μm, and the conversion rate between the position on the sensor [pixel] and the position in the Z direction [μm] is 1 [pixel] ⇔1 [μm]. Assuming that 0 ± 1 [pixel] is substituted for x in the relational expression shown in FIG. 10 (the left system expression: y = −0.4x ² −0.0x + 140.0), the above-described edge inclination amount is calculated as described above. The reference value y is y = 140.0 ± 0.4. Since the actual measurement value 139 is not included in the reference value 140.0 ± 0.4, in this case, it is determined that a mismatch occurs in the left system.

In the method using the edge inclination amount, in addition to determining the validity of the focus position detection result, it is possible to determine which system is inappropriate.
The method using the edge inclination amount is used only when determining which system is inappropriate. The threshold based on the above-described measurement accuracy is used for determining whether the system is inappropriate in the first place. good.

Note that it is predicted that two defocus amounts ΔZ obtained from the edge inclination amount are detected. Which defocus amount is used may be determined based on the position on the original sensor.
In addition, the absolute value of the edge tilt amount is meaningless when measuring reflecting surfaces with different reflectivities. In this case, the signal is normalized (normalized) (average signal strength is the value of the entire signal) And the like, and the edge inclination amount may be obtained.

  In this way, when it is determined that there is some contradiction in the focus position detection result, it may be determined that measurement is impossible and the apparatus may be stopped due to a measurement error. In order to suppress this, the following measures may be taken. For example, visual field movement to a known position where the reflectance is uniform, visual field movement to a nearby street line, movement to the second measurement point described in the sequence program in advance, or very close If the focus position is re-measured (focus measurement retry) at the destination (the place where it was moved) after moving to an arbitrary position, the sequence (device sequence or measurement sequence) ) Can be continued without stopping, and an inconsistent (incorrect) focus measurement value (focus result) can be avoided. Alternatively, when a plurality of signal processing algorithms are provided as signal processing algorithms for ALG-AF measurement, the most appropriate one of the signal processing algorithms may be selected.

As described above, according to the present embodiment, when measuring the position of the reflecting surface (the amount of deviation from the reference position) in relation to the imaging position of the two systems of obliquely incident light on the light receiving sensor, the interval is measured. By utilizing the imaging position on the sensor that will inevitably be measured, it is possible to perform self-determination of the measurement result.
Similarly, it is possible to check which of the two systems is abnormal by using the edge inclination amount.
In addition, the determination can be easily performed without the need for separate adjustment or manufacturing, and as a result, high-precision measurement without self-contradiction can be expected.

  In addition, this Embodiment was described in order to make an understanding of this invention easy, and does not limit this invention at all. Each element disclosed in the present embodiment includes all design changes and equivalents belonging to the technical scope of the present invention, and various suitable modifications are possible.

FIG. 1 is a view showing the arrangement of an exposure apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing the configuration of the position detection apparatus of the exposure apparatus shown in FIG. FIG. 3 is a diagram showing a configuration of the alignment focus detection apparatus shown in FIG. FIG. 4 is a diagram showing an illumination slit of the alignment focus detection apparatus shown in FIG. FIG. 5 is a view showing an AF slit image on the wafer in the alignment focus detection apparatus shown in FIG. 6A and 6B are diagrams showing pattern images on the image sensor of the alignment focus detection apparatus shown in FIG. FIG. 7 is a diagram illustrating an example of a signal detected by the ALG-AF sensor illustrated in FIG. FIG. 8 is a diagram showing light reception signals of two slit pattern images for detecting the relative positional relationship between the two right and left systems of obliquely incident light. FIG. 9 is a diagram illustrating a correspondence relationship between the defocus amount, the edge tilt amount, and the positions on the sensors of the left and right systems. FIG. 10 is a diagram illustrating a correspondence relationship between the defocus amount, the edge tilt amount, and the positions on the left and right sensors on the two-dimensional functions.

Explanation of symbols

PD ... position detection device IL ... exposure illumination system R ... reticle RS ... reticle stage PL ... projection optical system W ... wafer WH ... wafer holder ZS ... Z stage SC ... stage control system XY ... XY stage MC ... main control systems 1a, 1b ... Light guide 2 ... ALG-AF illumination optical system 5 ... ALG-AF light receiving optical system 6 ... Aperture stop 7 ... Line sensor 13 ... Second objective lens 16 ... First objective lenses 22a, 22b ... Illumination slit 26 ... Signal Processing system

Claims (13)

Two detection lights are incident obliquely on the measurement target surface to be position-detected, the two reflected lights reflected on the measurement target surface are received, and the two reflected lights are received on the light receiving surface. In a position detection method for detecting a position of the measurement surface in a direction perpendicular to the measurement surface based on an interval between positions,
Whether or not a desired detection result detected based on the interval between the light receiving positions of the two reflected lights is appropriate is detected individually based on the light receiving positions of the two reflected lights. A position detection method comprising: a detection result confirmation step for determining based on two position detection results of the surface to be measured.   In the detection result confirmation step, the position detection result of the measurement surface detected based on the interval between the light receiving positions of the two reflected lights, and the reflected light with respect to the first detection light of the two detection lights The position measurement result detected based only on the position detection result of the surface to be measured detected based only on the light receiving position and the light receiving position of the reflected light with respect to the second detection light of the two detection lights The difference between the surface position detection results is detected, and if at least one of the differences is larger than a predetermined threshold, it is determined that the desired measurement result is not appropriate. 2. The position detection method according to 1.   The predetermined threshold is sufficient to absorb the fluctuation based on the play component in the position fluctuation in the position detection direction of the surface to be measured and the position fluctuation based on the measurement reproducibility of the position of the surface to be measured. The position detection method according to claim 2, wherein the position detection method is set to a different value. The detection light is projected with a line-and-space image in which a plurality of lines are arranged at a predetermined pitch,
The position of the surface to be measured is detected based on a line and space image formed by reflected light of the detection light,
The predetermined threshold is a variation in the position of the measurement surface that occurs when a pitch jump occurs in the process of detecting the position of the measurement surface based on a line-and-space image formed by the reflected light. The position detection method according to claim 2, wherein the position detection method is set to a value sufficient to absorb the fluctuation.   In the detection result confirmation step, when it is determined that the desired detection result is not appropriate, based on the edge inclination amount of the component corresponding to each reflected light in the light reception signal waveforms of the two reflected lights, The position detection method according to any one of claims 1 to 4, wherein the position detection system using which of the two reflected lights uses a position detection system is detected.   The detection result confirmation step redetects the position of the measurement target surface when it is determined that the desired detection result is not appropriate. The position detection method described.   When re-detecting the position of the surface to be measured, the surface to be measured is moved in a plane parallel to the surface, the detection light is incident on another part of the surface to be measured, and the surface to be measured is The position detection method according to claim 6, wherein the position of the measurement surface is detected.   The position detection according to any one of claims 1 to 7, wherein in the detection result confirmation step, if it is determined that the desired detection result is not appropriate, a warning to that effect is issued. Method. By the position detection method according to any one of claims 1 to 8, the position of the exposed surface of the substrate is detected,
Align the position of the exposed surface of the substrate with the in-focus position of the alignment measurement system,
An alignment measurement method, comprising: measuring a position of a desired pattern formed on the substrate by the alignment measurement system. By the position detection method according to any one of claims 1 to 8, the position of the exposed surface of the substrate is detected,
Align the position of the exposed surface of the substrate with the in-focus position of the projection optical system;
An exposure method comprising: projecting an image of a predetermined pattern onto the substrate by the projection optical system, and transferring and exposing the pattern onto the substrate. Two detection lights are incident on the measurement target surface of the position detection target obliquely, the two reflected lights reflected by the measurement target surface are received, and the respective light receiving positions on the light receiving surface of the two reflected lights. A position detection device that detects a position of the surface to be measured in a direction perpendicular to the surface to be measured, based on an interval between them,
Whether or not a desired detection result detected based on the interval between the light receiving positions of the two reflected lights is appropriate is detected individually based on the light receiving positions of the two reflected lights. And a detection result confirming means for determining based on the two position detection results of the surface to be measured. The position detection device according to claim 11 for detecting a position of an exposed surface of the substrate;
Alignment means for aligning the position of the exposed surface of the substrate;
An alignment measurement system for measuring the position of a desired pattern formed on the aligned substrate;
An alignment measurement apparatus comprising: The position detection device according to claim 11 for detecting a position of an exposed surface of the substrate;
Alignment means for aligning the position of the exposed surface of the substrate;
An exposure apparatus comprising: exposure means for transferring and exposing a predetermined pattern on the aligned substrate.

Images