JP2013187514A - Surface position detection method and device, and exposure method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect in high accuracy a surface position at many measurement positions of a surface to be measured without complicating too much an optical system.SOLUTION: An AF sensor 12 for detecting surface position information of a wafer surface Wa comprises: a light-transmitting optical system 14A for obliquely projecting a slender slit image onto the wafer surface Wa along a plane of incidence; a light-receiving optical system 14B for receiving reflected light of the wafer surface Wa and reforming a slit image; a deflection prism 32 formed with a slender light-receiving slit 33a along a longer direction of the reformed slit image; a vibration mirror 26AD for changing a defocus amount of the slit image; and a light-receiving element array 36 for detecting light passing the light-receiving slit 33a.

Description

  The present invention relates to a surface position detection technique for detecting surface position information of a surface to be measured, an exposure technique using this surface position detection technique, and a device manufacturing technique using this exposure technique.

  Conventionally, in a lithography process for manufacturing an electronic device (microdevice) such as a semiconductor element (an integrated circuit or the like) or a liquid crystal display element, a wafer (or glass) on which a resist pattern is applied to a reticle pattern via a projection optical system An exposure apparatus such as a stepper or a scanning stepper (scanner) is used to transfer the image onto the surface of a plate or the like. Conventionally, in such an exposure apparatus, the surface position (the position in the normal direction or the position in the optical axis direction of the projection optical system) of the surface of the wafer is detected by an autofocus sensor (hereinafter referred to as an AF sensor), and the detection result Based on the above, the surface of the wafer is focused on the image plane of the projection optical system by autofocusing during exposure.

  As a conventional AF sensor, a slit image is projected from an oblique direction onto a surface to be measured such as the surface of a wafer by a light transmission optical system, and reflected light from the surface is received by a light receiving optical system, and the slit image is obtained. An oblique incidence type detection device that re-images is known. In this case, when the surface position of the test surface changes, the position of the slit image to be re-imaged shifts laterally, so that the surface position of the test surface can be detected. Furthermore, in the conventional oblique incidence type detection device, the detection signal is synchronously detected in synchronization with the drive signal of the vibrating mirror provided in the light transmitting optical system or the light receiving optical system, thereby reducing the influence of disturbance light. (For example, refer to Patent Document 1).

JP 2007-48818 A

  Since the conventional AF sensor projects the slit image obliquely to the plurality of measurement positions on the test surface, it is difficult to reduce the arrangement pitch of the plurality of measurement positions on the test surface. If it is going to increase, an optical system will become complicated and adjustment of an optical system will also become complicated. Recently, it has been required to measure the surface position at more measurement positions arranged at a smaller pitch on the surface to be measured such as the surface of a wafer.

  In view of such circumstances, it is an object of an aspect of the present invention to detect a surface position with high accuracy at many measurement positions on a surface to be measured without complicating an optical system.

  According to the first aspect of the present invention, a surface position detection device for detecting surface position information of a surface to be detected is provided. This surface position detecting device receives a light transmission optical system that projects an image of a slit-like pattern in a direction along the incident surface from an oblique direction to the test surface, and light reflected by the test surface. A light receiving optical system for re-forming the slit-shaped image and a surface on which the slit-shaped image is re-formed, and an elongated slit-shaped opening on the surface along the longitudinal direction of the slit-shaped image A defocus system that periodically changes the defocus amount of the image of the slit pattern on the surface on which the slit opening is formed, and detects light that has passed through the slit opening. A photoelectric detector and a signal processing unit that obtains surface position information of the surface to be detected based on a detection signal of the photoelectric detector.

According to the second aspect, in the exposure apparatus that exposes the substrate with the exposure light via the pattern and the projection optical system, the position of at least one of the surface on which the pattern is formed and the surface of the substrate is detected. Therefore, an exposure apparatus including the surface position detection apparatus according to the first aspect is provided.
Moreover, according to the 3rd aspect, the surface position detection method which detects the surface position information of a to-be-tested surface is provided. This surface position detection method projects an image of an elongated slit pattern from the oblique direction to the direction along the incident surface on the surface to be measured, and receives the light reflected by the surface to be measured. An elongated slit arranged along the longitudinal direction of the image of the slit pattern on the surface where the image of the slit pattern is re-formed by receiving light through an optical system The light from the light receiving optical system is detected via the aperture, and the defocus amount of the image of the slit pattern is periodically changed on the surface where the slit aperture is formed. Surface position information of the test surface is obtained based on the light detection signal.

According to the fourth aspect, in the exposure method of exposing the substrate with the exposure light through the pattern and the projection optical system, the position of at least one of the surface on which the pattern is formed and the surface of the substrate is detected. Therefore, an exposure method using the surface position detection method of the third aspect is provided.
Further, according to the fifth aspect, the mask pattern is transferred to the substrate using the exposure apparatus according to the second aspect or the exposure method according to the fourth aspect, and the substrate on which the pattern is transferred is transferred to the substrate. Processing based on the pattern is provided.

  According to the aspect of the present invention, since the image of the elongated slit pattern is projected on the test surface, the image of the slit pattern is re-formed, and the amount of light of the re-formed image is passed through the slit-shaped opening. When the light is received, the measurement position of the surface position of the test surface can be easily increased only by increasing the number of light receiving elements arranged in the direction corresponding to the longitudinal direction of the regenerated image. Therefore, the surface position can be detected with high accuracy at many measurement positions on the surface to be measured without complicating the optical system so much.

It is a figure which shows schematic structure of the exposure apparatus which concerns on 1st Embodiment. 1A is a plan view showing a detection area of the AF sensor in FIG. 1, FIG. 1B is an enlarged view showing a plurality of slits of the light transmission slit portion 19 in FIG. 1, and FIG. 1C is a light receiving slit in FIG. It is an enlarged view which shows the slit image formed in a part. (A) is a figure which shows the optical path of the detection light which changes with an oscillating mirror in an AF sensor, (B), (C), (D) shows the slit image from which a defocused state mutually differs formed in a light-receiving slit part, respectively. FIG. 5E is a diagram showing an example of a detection signal obtained from one light receiving element of the light receiving element array. (A) is a figure which shows the optical path of the upper limit and lower limit of the detection light in an AF sensor, (B) is a top view which shows two area | regions with a different reflectance in the wafer surface. (A), (B), (C), and (D) are diagrams showing a state in which the defocus amount of the slit image projected on a portion including two regions having different reflectances on the wafer surface changes. . It is a flowchart which shows an example of the detection operation | movement of the focus position (surface position) of a wafer surface. It is a figure which shows the exposure apparatus which concerns on 2nd Embodiment. It is a flowchart which shows an example of the manufacturing process of an electronic device.

[First Embodiment]
A preferred first embodiment of the present invention will be described below with reference to FIGS.
FIG. 1 shows a schematic configuration of an exposure apparatus EX according to the present embodiment. The exposure apparatus EX is a scanning projection exposure apparatus (scanning exposure apparatus) that includes a scanning stepper (scanner). The exposure apparatus EX includes a projection optical system PL. In the following description, the exposure apparatus EX takes a Z-axis parallel to the optical axis AX of the projection optical system PL, and is within a plane orthogonal to the Z-axis (this embodiment is substantially a horizontal plane). The Y axis is taken in the direction in which the reticle and wafer are relatively scanned (direction perpendicular to the paper surface of FIG. 1), and the X axis is taken in the direction perpendicular to the Z axis and Y axis (direction parallel to the paper surface of FIG. 1). The description will be made assuming that the rotation (inclination) directions around the X, Y, and Z axes are the θx, θy, and θz directions, respectively.

  In FIG. 1, an exposure apparatus EX includes an illumination system ILS, a reticle stage RST that moves while holding a reticle R (mask) illuminated by illumination light (exposure light) IL for exposure from the illumination system ILS, and a reticle R. A projection optical system PL for projecting a pattern image onto a surface (hereinafter referred to as a wafer surface) Wa of a wafer W (substrate), a wafer stage WST that holds and moves the wafer W, and a computer that comprehensively controls the operation of the entire apparatus. A main control device 40 and other control systems are provided. Further, the exposure apparatus EX has positions (Z position, focus position, or surface position) in the optical axis direction (Z direction in the present embodiment) of the projection optical system PL in a plurality of measurement regions on the wafer surface Wa (surface to be measured). Is provided with an autofocus sensor (hereinafter referred to as an AF sensor) 12 (surface position detection device). The AF sensor 12 is an optical and oblique incidence detection device that projects a detection light beam obliquely onto a surface to be measured (details will be described later).

  The illumination system ILS has a light source and an illumination optical system. The illumination optical system includes, for example, a light amount distribution setting unit including a diffractive optical element or a spatial light modulator, an optical integrator (fly-eye lens, rod integrator) as disclosed in US Patent Application Publication No. 2003/0025890. Etc.), a fixed and variable field stop (reticle blind), a condenser optical system, etc. (all not shown). The illumination light IL from the illumination system ILS passes through a slit-like illumination area elongated in the X direction on the pattern surface (lower surface) of the reticle R defined by the reticle blind, with a substantially uniform illuminance, via a mirror MI for bending the optical path. Illuminate. As the illumination light IL, for example, ArF excimer laser light (wavelength 193 nm) is used. As illumination light, KrF excimer laser light (wavelength 248 nm), harmonic of a YAG laser, harmonic of a solid laser (such as a semiconductor laser), or a bright line (such as i-line) of a mercury lamp can be used.

  Reticle stage RST is mounted on an upper surface parallel to the XY plane of a reticle base (not shown) via an air bearing. The reticle stage RST can be finely driven at least in the X, Y, and θz directions on its upper surface by a drive system (not shown) including, for example, a linear motor and the like, and scanning designated in the scanning direction (Y direction). It can be driven at speed. Position information of the reticle stage RST (including the position in the X direction, the Y direction, and the rotation angle in the θz direction) is measured by a laser interferometer (not shown), and based on the measured value and control information from the main controller 40. The stage control system 42 controls the drive system.

  The projection optical system PL converts an image of a circuit pattern in the illumination area of the pattern area of the reticle R under illumination light IL into a slit-like exposure area (illumination area and Formed in a conjugate region). The projection optical system PL is composed of a refractive system or a catadioptric system, and has a predetermined projection magnification β (for example, a reduction magnification of 1/4 times, 1/5 times, etc.), for example, on both sides telecentric. The wafer W includes, for example, one obtained by applying a photoresist (photosensitive agent) with a predetermined thickness (for example, about several tens to 200 nm) on the surface of a disk-shaped semiconductor wafer having a diameter of about 200 mm to 450 mm.

When the exposure apparatus EX performs exposure by the immersion method, illumination is performed on a local region between the optical element on the most image plane side (wafer W side) and the wafer W constituting the projection optical system PL. A local liquid immersion mechanism (not shown) for supplying a liquid that transmits the light IL is provided. The local liquid immersion mechanism is disclosed in, for example, US Patent Application Publication No. 2007/242247.
Wafer stage WST is placed on the upper surface of wafer base WB parallel to the XY plane via an air bearing. Wafer stage WST has an XY stage that can move in the X and Y directions on the upper surface of wafer base WB, and that can be slightly rotated in the θz direction, and a Z stage that is fixed to the upper part of XY stage. The Z stage holds the wafer W via the wafer table WTB and controls the Z position of the wafer table WTB (and the wafer W) and the inclination angles in the θx direction and the θy direction. On the upper surface of wafer table WTB, flat plate 10 having an opening in which wafer W is placed at the center is provided, which is a surface having the same height as the surface of the wafer. When the exposure apparatus EX is a liquid immersion type, the surface of the flat plate 10 is subjected to a liquid repellency treatment.

  Position information of wafer stage WST on the upper surface of wafer base WB (including at least the position in the X direction, the Y direction, and the rotation angle in the θz direction) is measured by a laser interferometer (not shown). Based on the control information from 40, stage control system 42 controls the operation of the XY stage in wafer stage WST via a drive system (not shown) such as a linear motor. Further, based on information on the Z position of wafer surface Ws measured by AF sensor 12, main controller 40 controls Z stage of wafer stage WST via stage control system 42.

  Wafer stage WST also includes an aerial image measurement system (not shown) for measuring the position of the image of alignment mark of reticle R by projection optical system PL, and in the vicinity of projection optical system PL, an alignment mark of wafer W is aligned. A wafer alignment system (not shown) for measuring the position is provided. The reticle R and the wafer W are aligned based on the measurement results of the aerial image measurement system and the wafer alignment system.

  During exposure of wafer W, illumination light IL from illumination system ILS is shielded by a movable reticle blind, and one shot area of wafer W is projected onto projection optical system PL by movement of wafer stage WST in the X and Y directions. (Step movement) before this exposure area. Thereafter, irradiation of the illumination light IL to the wafer W is started, and the reticle stage RST and the wafer stage WST are exposed while exposing the shot area of the wafer W with an image of a part of the pattern of the reticle R by the projection optical system PL. By driving and moving the reticle R and the wafer W in synchronization with the Y direction, the pattern image of the reticle R is scanned and exposed in the shot area. By repeating the step movement and the scanning exposure, the image of the pattern of the reticle R is exposed on the entire shot area of the wafer W by the step-and-scan method.

  Further, at the time of scanning exposure of each shot area of the wafer W, the main controller 40 controls the stage control system 42 based on the measurement results of the Z position of a plurality of measurement areas (measurement points) on the surface of the wafer W by the AF sensor 12. Then, the Z stage of wafer stage WST is driven so that wafer surface Ws is focused on the image plane of projection optical system PL by the autofocus method. As a result, the pattern image of the reticle R is exposed to each shot area of the wafer W with high resolution.

  Next, the configuration and operation of the AF sensor 12 of this embodiment will be described in detail. The AF sensor 12 includes a light source system 16 for emitting a detection light beam L, a deflection prism 18 formed with a plurality of light-sending slits 19a irradiated with the light beam L, and a plurality of slit images on a wafer surface Wa (test surface). A light-transmitting optical system 14A that projects from an oblique direction, a light-receiving optical system 14B that receives a light beam L reflected by the wafer surface Wa, and a deflection prism 32 in which a plurality of light-receiving slits 33a are formed. Further, the AF sensor 12 is disposed in the light transmission optical system 14A, and drives a vibrating mirror 26AD such as a galvanometer mirror that reflects the light beam L and periodically changes the angle of the light beam L in the θy direction, and the vibrating mirror 26AD. A signal for obtaining information on Z positions (surface positions) in a plurality of measurement areas of the wafer surface Wa from a mirror control system 44, a detection system 14C for detecting the light beam L via the deflecting prism 32, and detection signals of the detection system 14C. A processing system 46 is included.

  First, the light source system 16 emits a non-polarized light beam L made of visible light and / or near infrared light having a wide wavelength range, for example, a light source 17A made of a light emitting diode or a halogen lamp, and the light beam L into a substantially parallel light beam. A condenser lens 17B. The light beam L is preferably light with low photosensitivity to the resist applied to the wafer W and low coherence. The light beam L converted into a substantially parallel light beam by the condenser lens 17B is incident on the deflecting prism 18 and is refracted by the deflecting prism 18 so that the principal ray is deflected so as to travel substantially in the −Z direction. On the exit surface of the deflecting prism 18, a light transmission slit portion 19 having a configuration in which a plurality of elongated light transmission slits 19 a (line patterns) are periodically arranged in a light shielding film is provided.

  As shown in FIG. 2B, the X1 direction parallel to the longitudinal direction of the plurality of elongated light transmitting slits 19a of the light transmitting slit portion 19 is a direction corresponding to the X direction of the wafer surface Wa. In FIG. 2B, if the direction orthogonal to the X1 direction is the Y1 direction (a direction parallel to the Y direction of the wafer surface Wa), the line width d1 of the light transmission slit 19a in the Y1 direction is, for example, 10 to 20 μm. The pitch (period) p1 of the arrangement of the slits 19a in the Y1 direction is about several times the line width d1. As an example, the number of the light transmission slits 19a is about several tens to several hundreds.

Note that the light flux of the light source 17A may be transmitted to a position close to the side surface of the projection optical system PL by, for example, a flexible light guide (not shown).
In FIG. 1, a light beam L that has passed through a plurality of light transmission slits 19a of the deflecting prism 18 enters a first objective lens 20A of a light transmission optical system 14A. The light beam L condensed by the first objective lens 20A is bent in the + X direction by a predetermined angle (for example, several degrees to 10 degrees) smaller than 90 degrees by the vibrating mirror 26AD, and then the second objective. Through the lens 20B and the prism 28A that shifts the optical path in the −Z direction, the light is projected obliquely into a projection area 29 that is elongated in the X direction on the wafer surface Wa. Images of a plurality of elongated light transmission slits 19a are formed in the projection area 29 by the light beam L at a constant pitch in the Y direction.

  The first objective lens 20A, the second objective lens 20B, and the prism 28A constitute a light transmission optical system 14A. The light transmission optical system 14A is an image that optically conjugates the exit surface of the deflecting prism 18 (formation surface of the light transmission slit portion 19) and the image surface of the projection optical system PL (wafer surface Wa when focused). It is an optical system. Further, a straight line intersecting the incident surface of the principal ray of the light beam L projected obliquely on the wafer surface Wa and the image plane of the projection optical system PL (wafer surface Wa when focused) is parallel to the X axis (X direction). ), And the longitudinal direction of the image of the light transmission slit 19a is also the X direction.

  The oscillating mirror 26AD is disposed in the vicinity of a plane (pupil plane) conjugate with the exit pupil of the light transmission optical system 14A. The oscillating mirror 26AD oscillates the reflected light between the lower optical path P1 and the upper optical path P2 of the dotted line, that is, within the incident surface of the light beam L with respect to the wafer surface Wa. Further, in a state where the wafer surface Wa is coincident with the image plane of the projection optical system PL, the formation surface of the light transmission slit portion 19 and the wafer surface Wa satisfy the Scheinproof condition with respect to the light transmission optical system 14A. The images of the plurality of light transmission slits 19 a are accurately formed over the entire projection area 29. The light transmission optical system 14A is a so-called double-sided telecentric optical system. As an example, the numerical aperture is about 0.01 to 0.1, the projection magnification is approximately equal to several times, and two arbitrary light transmission slits. The pitch p1 of 19a and the pitch in the Y direction of the two images of the corresponding wafer surface Wa are the same magnification over the entire surface of the wafer surface Wa.

  As shown in FIG. 2A, in the projection area 29, there are J light transmission slits 19a (J is an integer of several tens to several hundreds) by the light beam L projected from the light transmission optical system 14A. An elongated image (hereinafter referred to as a slit image) 37j (j = 1 to J) in the X direction is formed at a pitch p in the Y direction. The pitch p is about the same as the pitch p1 of the light transmission slit 19a or several times the pitch p1. The length of the elongated slit image 37j (line pattern image) in the X direction is, for example, slightly shorter than the maximum width of the test surface in the X direction. Therefore, when the diameter of the wafer W is about 300 mm, the length in the X direction of the image 37j of the light transmission slit is about 300 mm. Due to the vibration of the oscillating mirror 26AD, the position of each slit image 37j as a whole periodically changes in the X direction and the defocus amount changes, but the average position in the Y direction does not change.

  In the present embodiment, the projection area 29 on which the plurality of slit images 37j are projected has I measurement areas MAi (i = 1) having the same width in the X direction (I is an integer of several tens to 300). To I). The center of the i-th measurement area MAi can be regarded as the i-th measurement point at the Z position on the wafer surface Wa. As will be described later, the number I of the measurement areas MAi is the same as the number of the light receiving elements in the light receiving element array 36 in the detection system 14C, and the pitch of the array in the X direction of the measurement areas MAi is the light receiving elements in the light receiving element array 36. For example, it can be easily reduced to about 1 mm in accordance with the pitch of the arrangement. Furthermore, the number of measurement areas MAi (measurement points) can be easily increased only by increasing the number of light receiving elements in the light receiving element array 36.

  In FIG. 1, a light beam L projected onto the wafer surface Wa is reflected by the wafer surface Wa and enters the first objective lens 30A via a prism 28B that shifts the optical path in the + Z direction. Then, the light beam L that has passed through the first objective lens 30A is incident on the second objective lens 30B with its optical path bent substantially in the + Z direction via the mirror 26B. The light beam L emitted from the second objective lens 30B forms images of a plurality of elongated slit images 37j in the projection area 29 on the wafer surface Wa in the light receiving slit portion 33 formed on the incident surface of the deflecting prism 32.

  As shown in FIG. 2 (C), the light receiving slit portion 33 is in the same arrangement as the images of a plurality of slit images 37j (hereinafter referred to as slit images) 38j (j = 1 to J) in the light shielding film. In this configuration, a plurality of light receiving slits 33a each having an elongated opening pattern having substantially the same shape as the slit image 38j at the time are provided in parallel to the Y2 direction (direction parallel to the Y direction of the wafer surface). The slit image 38j is also an image 19aP obtained by the light transmission optical system 14A and the light reception optical system 14B of the plurality of light transmission slits 19a. Due to the vibration of the vibration mirror 26AD, the plurality of slit images 38j as a whole periodically move in the X2 direction (direction corresponding to the X direction of the wafer surface), and the defocus amount changes periodically.

  The light receiving optical system 14B is constituted by the prism 28B, the first objective lens 30A, the mirror 26B, and the second objective lens 30B. Regarding the light receiving optical system 14B, the image plane of the projection optical system PL (wafer surface Wa when focused) and the incident surface of the deflecting prism 32 (formation surface of the light receiving slit portion 33) are optically conjugate. In addition, the wafer surface Wa and the incident surface of the deflecting prism 32 are arranged so as to satisfy the Scheinproof condition with respect to the light receiving optical system 14B in a state where the wafer surface Wa is focused on the image plane of the projection optical system PL. Has been. Therefore, the image 38j of the slit image 37j formed in the projection area 29 of the wafer surface Wa is accurately re-imaged over the entire incident surface of the deflecting prism 32. The light receiving optical system 14B is a double-sided telecentric optical system. As an example, the numerical aperture is about 0.01 to 0.1, the projection magnification is approximately equal to a fraction, and two points on the wafer surface Wa. The interval and the interval between two corresponding conjugate points on the incident surface of the deflecting prism 32 are the same magnification over the entire surface.

  In this case, as shown in FIG. 3A, in the state where the wafer surface Wa is focused on the image surface, the center point in the X direction of the wafer surface Wa along the solid line optical path from the light transmission optical system 14A. Assume a light beam L irradiated to B0. The light beam L is reflected by the wafer surface Wa and then collected by the light receiving optical system 14B, and forms a slit image in a focused state at a central point C0 of the light receiving slit portion 33. At this time, as shown in FIG. 3C, slit images 38j having substantially the same size are formed at substantially the same positions as the light receiving slits 33a of the light receiving slit portion 33, and the amount of light passing through the light receiving slits 33a is maximized. Become. From this state, when the wafer surface Wa is displaced in the Z direction (surface position measurement direction) and moved to the position A1 in the + Z direction, the light beam passing through the same optical path as the light beam reflected at the point B0 is a dotted line. As shown, the light beam is focused on a point B1 that is separated from the point B0 by δX in the + X direction on the wafer surface Wa. This light beam is actually reflected by the wafer surface Wa at the position A1, and then condensed by the light receiving optical system 14B to form a slit image at a point C1 separated from the light receiving slit portion 33 by δZ2 in the + Z direction. Therefore, as shown in FIG. 3B, a defocused slit image 38j is formed on each light receiving slit 33a of the light receiving slit portion 33, and the amount of light passing through each light receiving slit 33a is reduced.

  On the other hand, when the wafer surface Wa moves to the position A2 in the −Z direction, the light beam passing through the same optical path as the light beam reflected at the point B0 is δX from the point B0 to the −X direction on the wafer surface Wa as indicated by the dotted line. It becomes a light beam condensed at a point B2 that is far away. This light beam is actually reflected by the wafer surface Wa at the position A2, and then condensed by the light receiving optical system 14B to form a slit image at a point C2 away from the light receiving slit portion 33 by δZ2 in the −Z direction. Therefore, as shown in FIG. 3D, a defocused slit image 38j is formed on each light receiving slit 33a of the light receiving slit portion 33, and the amount of light passing through each light receiving slit 33a is reduced. Therefore, when the Z position of the wafer surface Wa changes, the detection signal S1 obtained by photoelectrically converting the amount of light passing through each of the light receiving slits 33a of the light receiving slit portion 33 is, as shown in FIG. 3E, the wafer surface Wa. Is at the best focus position BF, and decreases as the wafer surface Wa moves away from the position BF. For this reason, the Z position (displacement δZ with respect to the position BF) of the wafer surface Wa can be detected from the detection signal S1. However, if the detection signal S1 is simply used, it is not known whether the Z position is displaced in the + Z direction or the −Z direction with respect to the position BF. Therefore, in this embodiment, the detection signal S1 is vibrated as described later. Synchronous rectification is performed by the drive signal of the mirror 26AD.

In FIG. 3A, as an example, the incident angle φ of the light beam L incident on the wafer surface Wa from the light transmission optical system 14A is set to 86 °, and the wafer surface Wa is displaced in the Z direction (to the position A1 or A2). Is 1 μm, the distance δX from the point B0 to the point B1 or B2 is approximately 14.3 μm as follows.
δX = 1 × tan 86 ° = 14.3 (μm) (1)
Further, if the light receiving optical system 14B is, for example, equal magnification, the defocus amount (interval δZ2) of the slit image 38j in the light receiving slit portion 33 is substantially equal to the distance δX of Expression (1), and the defocus amount is approximately 14.3x magnification. The magnification of the defocus amount in the light receiving slit portion 33 with respect to the defocus amount of the wafer surface Wa can also be referred to as a confocal effect of the light receiving optical system 14B. In other words, even if the numerical aperture of the light receiving optical system 14B is 0.02, the numerical aperture is substantially equivalent to 0.28 (= 0.02 × 14) due to the confocal effect, and the surface position is detected. High detection accuracy can be obtained.

  In FIG. 1, a light beam L that has passed through a plurality of light receiving slits 33a on the incident surface of the deflecting prism 32 is received by a relay optical system 34, and a plurality of light receiving elements PEi (i = i = a photodiode formed by a light receiving element array 36, for example). 1 to I) are relayed to the light receiving surface. The detection signals S1 of the plurality of light receiving elements PEi are supplied to the signal processing system 46. As the light receiving element array 36, for example, a CCD or CMOS type one-dimensional line sensor can also be used. Instead of the light receiving element array 36, a light receiving element array having a plurality of light receiving element arrays in a plurality of columns or a two-dimensional image pickup element may be used.

  In FIG. 2C, the plurality of light receiving elements PEi (i = 1 to I) of the light receiving element array 36 viewed from the arrangement surface of the plurality of light receiving slits 38j of the light receiving slit portion 33 through the relay optical system 34 are shown. Show. The number I of light receiving elements PEi is the same as the number of measurement areas MAi set in the projection area 29 of the wafer surface Wa in FIG. 2A, and the i-th light receiving element PEi causes i in the projection area 29 to be i. Of the light beam reflected by the first measurement region MAi, the light beam that has passed through the corresponding region (region conjugate with the measurement region MAi) of the plurality of light receiving slits 38j of the light receiving slit portion 33 is received.

  The signal processing system 46 performs synchronous rectification of the detection signal S1 output from each light receiving element PEi individually using the drive signal of the oscillating mirror 26AD supplied from the mirror control system 44, so that the i th of the wafer surface Wa is obtained. The displacement δZi of the Z position of the measurement area MAi from the best focus position BF is obtained. Synchronous rectification in this case is, for example, sampling the detection signal every half cycle of the drive signal and obtaining the difference between the two sampled signals. As shown in FIG. 3E, the detection signal S1 is a signal that becomes a maximum value at the position BF, and the displacement δZi can be obtained with high accuracy by the synchronous rectification. Since there are irregularities (steps) on the wafer surface Wa due to the processing of the previous processes, the displacements δZi are usually slightly different from each other. Information on the obtained Z position (displacement δZi) of all measurement areas MAi on the wafer surface Wa is supplied to the main controller 40. The relay optical system 34 and the light receiving element array 36 constitute a detection system 14C. Of the AF sensor 12, the part of the optical system excluding the mirror control system 44 and the signal processing system 46 is supported by a frame (not shown) that holds the projection optical system PL.

  Here, when the light beam L is vibrated in the θy direction by the vibration mirror 26AD, the defocus amount of the slit image formed in the light receiving slit portion 33 changes, and the AF sensor 12 causes the layer in front of the wafer surface Wa to be changed. A description will be given of the fact that the influence of reflected light from a plurality of adjacent circuit patterns (underlying patterns) or wafer surfaces Wa having different reflectances and adjacent to each other can be reduced. Here, as shown in FIG. 4A, as an example, when the wafer surface Wa is focused on the image plane and the vibrating mirror 26AD is at the center (neutral position) of the vibration range, the light transmission optical system Assume a light beam L irradiated to a center point B0 in the X direction of the wafer surface Wa along a solid optical path from 14A. The light beam L is reflected by the wafer surface Wa and then forms a slit image at a center point C0 of the light receiving slit portion 33.

  From this state, when the oscillating mirror 26AD rotates to the clockwise lower limit position and the optical path of the light beam L incident on the point B0 of the wafer surface Wa moves to the dotted optical path P1, the light beam L along the optical path P1 is A slit image is formed at a point B01 that is separated from the point B0 in the + Z direction after being reflected by the wafer surface Wa. Accordingly, since all the slit images are projected on the wafer surface Wa in a defocused state, the slit images formed on the light receiving slit portion 33 by the reflected light from the wafer surface Wa are also defocused. In this case, the light beam passing through the point B01 is incident on the light receiving slit portion 33 at a position away from the point C0 in the direction corresponding to the X direction. The light beam L11 incident on the point B0 on the wafer surface Wa forms a slit image at a point B11 away from the wafer surface Wa, and then defocuses in the + Z direction from the point C0 along the optical axis of the light receiving optical system 14B. Since a slit image is formed at the position C11, the amount of light passing through the light receiving slit decreases.

  On the other hand, when the vibrating mirror 26AD rotates to the counterclockwise upper limit position and the optical path of the light beam L incident on the point B0 on the wafer surface Wa moves to the dotted optical path P2, the light beam along the optical path P2 L forms a slit image at a point B01 above the point B0 and is then reflected by the wafer surface Wa. Therefore, even in this state, the entire slit image is projected on the wafer surface Wa in a defocused state, and the slit image formed in the light receiving slit portion 33 by the reflected light from the wafer surface Wa is also defocused. A light beam L12 that forms a slit image at a point B12 that is distant from the point B0 in the -X direction in the + Z direction is reflected at the point B0 on the wafer surface Wa, and then is pointed along the optical axis of the light receiving optical system 14B. Since the slit image is formed at the position C12 defocused in the −Z direction, the amount of light passing through the light receiving slit is reduced.

  As described above, the vibration of the oscillating mirror 26AD periodically changes the defocus amount of the slit image formed at the center of the light receiving slit portion 33, and similarly, the slit image formed at the other portion of the light receiving slit portion 33. However, the defocus amount changes periodically. Further, in the case of FIG. 4A, the wafer surface Wa where the point B0 is located is at the best focus position, but the light beam is emitted by the vibrating mirror 26AD in a state where the wafer surface Wa is shifted by δZ from the best focus position. When L is vibrated, the defocus amount of the slit image formed in the light receiving slit portion 33 periodically changes around the defocus amount corresponding to the displacement δZ. Therefore, the displacement δZ of the wafer surface Wa from the best focus position can be obtained by synchronously rectifying the detection signal output from the light receiving element array 36 with the drive signal of the oscillating mirror 26AD.

  As shown in FIG. 4B, in the projection area 29 of the slit image 37j on the wafer surface Wa, for example, the i-th measurement area MAi has a high reflectivity portion (high reflectivity portion) 48A and a reflectivity. It is assumed that it is set at the boundary with the low part (low reflectance part) 48B. At this time, by vibrating the oscillating mirror 26AD, the plurality of slit images 37j projected on the wafer surface Wa move in the X direction as a whole, and the defocus amount on the wafer surface Wa periodically changes.

  That is, when the slit image 37j is moved in the −X direction on the wafer surface Wa by the oscillating mirror 26AD, the slit image 37j is in the center of the moving range in the X direction as shown in FIG. Assume that the slit image 37j is clearly formed in a focused state. In this case, when the slit image 37j is further moved in the −X direction by the oscillating mirror 26AD, the defocus amount of the slit image 37j is maximized as shown in FIG. Thereafter, the slit image 37j starts to move in the + X direction by the oscillating mirror 26AD, and when the slit image 37j returns to the center in the movement range in the X direction as shown in FIG. It is clearly formed in the focused state again. When the slit image 37j is further moved in the + X direction by the oscillating mirror 26AD, the defocus amount of the slit image 37j is maximized as shown in FIG. Hereinafter, the operations of FIGS. 5A to 5D are periodically repeated.

  In this case, in the state of FIG. 5A, the light beam reflected by the measurement area MAi at the boundary between the high reflectance part 48A and the low reflectance part 48B is received by the i-th light receiving element of the light receiving element array 36. Shall be. At this time, as shown in FIG. 5B or FIG. 5D, even if the position of the slit image 37j moves in the X direction on the wafer surface Wa, the light beam incident on the i-th light receiving element is high. Among the light beams reflected by the measurement area MAi at the boundary between the reflectivity part 48A and the low reflectivity part 48B, the light beam has passed through the corresponding light receiving slit 33a. Therefore, the detection signal from the i-th light receiving element periodically changes according to the vibration of the oscillating mirror 26AD (the defocus amount of the slit image 37j), but the high reflectivity portion 48A and the low reflection in the measurement region MAi. The area ratio with the rate part 48B does not change. Therefore, the slit image 37j is moved in the X direction in order to change the defocus amount of the slit image 37j in a state where the high reflectance portion 48A and the low reflectance portion 48B are formed adjacent to each other on the wafer surface Wa. Even if the detection signal is detected, the detection signal from the i-th light receiving element accurately changes in accordance with the defocus amount, and the Z position of the measurement region MAi is measured by the presence of the high reflectivity portion 48A and the low reflectivity portion 48B. The accuracy is not reduced.

  On the other hand, when a slit image is projected onto the wafer surface Wa and the slit image is vibrated as in the conventional technique, the slit image is moved so as to have a high reflectance in the area where the slit image is projected. If the area ratio of the part and the low reflectance part changes, the detection signal also changes due to factors other than the defocus of the slit image (change in the area ratio or the influence of the ground pattern), and the measurement accuracy of the Z position decreases. There is a fear. According to the AF sensor 12 of the present embodiment, the influence of the base pattern on the wafer surface Wa and the presence of the high reflectance portion and the low reflectance portion on the wafer surface Wa are reduced.

Hereinafter, in the exposure apparatus EX of the present embodiment, the Z position on the surface of the wafer W is measured using the AF sensor 12 under the control of the main controller 40, and the wafer W is exposed using this measurement result. An example will be described with reference to the flowchart of FIG. This operation is controlled by the main controller 40.
First, in step 102 in FIG. 6, wafer stage WST is driven to move wafer surface Wa to projection area 29 of AF sensor 12. In the next step 104, light emission of the light source 17A is started, and the vibration of the vibrating mirror 26AD is started by the mirror control system 44. In the next step 106, as shown in FIG. 1, the light beam L emitted from the light source 17A illuminates the light transmission slit portion 19 of the deflecting prism 18. The light beam L that has passed through the plurality of elongated light-sending slits 19a of the light-sending slit unit 19 obliquely enters the projection area 29 of the wafer surface Wa (surface to be measured) via the light-sending optical system 14A and the vibrating mirror 26AD. A slit image 37j (line pattern image) is projected.

  In the next step 108, the light beam L reflected by the wafer surface Wa is received through the light receiving optical system 14B and forms an image of a plurality of light transmitting slits 19a in the light receiving slit portion 33 of the deflecting prism 32. In the next step 110, the light beam that has passed through the plurality of light receiving slits 33 a is detected by the light receiving element array 36, and the signal processing system 46 receives detection signals output from the plurality of light receiving elements in the light receiving element array 36. Sampling is performed in synchronization with the drive signal. In the next step 112, the signal processing system 46 obtains Z positions in a plurality of measurement areas MAi on the wafer surface Wa using a plurality of sampled detection signals, and stores the obtained Z positions in an internal storage device. . As a result, the Z positions of the plurality of measurement areas MAi (measurement points) in the first row of the wafer surface Wa are measured.

  In the next step 114, when the measurement of the Z position is continued, the process proceeds to step 116, the wafer stage WST is driven, and the projection area 29 of the AF sensor 12 is applied to the AF sensor 12 as shown in FIG. The wafer W is moved in the Y direction, and the next measurement target area on the wafer surface Wa is moved to the projection area 29. Thereafter, the operation returns to step 106, and the Z positions of the plurality of measurement areas MAi in the measurement target area are measured and stored. As a result, the Z positions of the plurality of measurement areas MAi in the second row of the wafer surface Wa are measured. Thereafter, the Z position of a plurality of measurement areas MAi in the third row, the fourth row,... That are gradually arranged in the Y direction on the wafer surface Wa is measured by the AF sensor 12 while moving the wafer W in the Y direction. Then, when the measurement of the Z position is completed over the entire wafer surface Wa, it is determined in step 114 that the measurement is completed, the operation proceeds to step 118, the light emission of the light source 17A is stopped, and the vibration of the vibration mirror 26AD is reduced. By stopping, the measurement operation of the Z position is completed. At this time, Z position measurement results in a plurality of measurement areas (measurement points) in a plurality of rows on the entire wafer surface Wa stored in step 112 are supplied to the main controller 40.

  Thereafter, in step 120, wafer stage WST is driven to move the shot area to be exposed on wafer W to the front of the exposure area of projection optical system PL (step movement). In the next step 122, the reticle is applied to the shot area on the wafer surface Wa while focusing the wafer surface Wa on the image plane of the projection optical system PL by the autofocus method based on the measurement result of the Z position stored in step 112. An R pattern image is scanned and exposed. After the operations in steps 120 and 122 are performed for all shot regions of the wafer W, the exposure for the wafer W is completed in step 124, and the measurement and exposure of the Z position for the next wafer are performed.

  As described above, in the present embodiment, a large number of measurement areas (measurement points) at the Z position of the AF sensor 12 can be arranged at a fine pitch in the X direction, and the influence of the ground pattern on the wafer surface Wa is small. The Z position distribution can be measured with high precision at a fine pitch. Therefore, the wafer surface Wa can be focused on the image plane of the projection optical system PL with higher accuracy, and the pattern image of the reticle R can be exposed onto the wafer with higher accuracy.

The effects and the like of this embodiment are as follows.
The AF sensor 12 (surface position detection device) provided in the exposure apparatus EX of the present embodiment is a Z position that is a position in the normal direction of the wafer surface Wa (surface to be measured) (a position in the optical axis direction of the projection optical system PL). This is a device for detecting (surface position). The AF sensor 12 receives a light reflected by the wafer surface Wa and projects an image 38j of the slit image on the wafer surface Wa. And a deflecting prism 32 having a surface on which a slit image 38j is re-formed, and a light-receiving slit 33a formed of an elongated opening along the longitudinal direction of the slit image 38j. Have. The AF sensor 12 further includes a vibrating mirror 26AD that periodically changes the defocus amount of the slit image 38j on the surface on which the light receiving slit 33a is formed, a light receiving element array 36 that detects light that has passed through the light receiving slit 33a, and a light receiving element. A signal processing system 46 for obtaining surface position information of the wafer surface Wa based on the detection signal of the element array 36 is provided.

  In addition, the method of detecting the Z position (surface position) of the wafer surface Wa using the AF sensor 12 is a method in which an elongated slit image 37j is passed through the light transmission optical system 14A from the oblique direction to the wafer surface Wa along the incident surface. (Step 106), the light reflected by the wafer surface Wa is received through the light receiving optical system 14B to re-form the slit image 38j (part of step 108), and the slit image 38j is re-formed. On the surface, light from the light receiving optical system 14B is detected through a long and narrow light receiving slit 33a disposed along the longitudinal direction of the slit image 38j (part of step 108), and the surface on which the light receiving slit 33a is formed. The defocus amount of the slit image 38j is periodically changed (step 110), and the Z position of the wafer surface Wa is obtained based on the light detection signal from the light receiving optical system 14B (step 110). Flop 112).

  According to the present embodiment, since the elongated slit image 37j is projected on the wafer surface Wa, the image (slit image) 38j of the slit image 37j is re-formed, and the light quantity of the re-formed slit image 38j is received. When light is received through the slit 33a, the number of measurement areas (measurement positions) of the surface position of the wafer surface Wa can be reduced by simply increasing the number of light receiving elements PEi arranged in the direction corresponding to the longitudinal direction of the slit image 38j. Can easily increase. Further, when the surface position of the wafer surface Wa changes, the defocus amount of the slit image 38j formed on the surface on which the light receiving slit 33a is formed changes, and the amount of light passing through the light receiving slit 33a changes. The surface position information can be detected. Therefore, it is possible to detect the surface position with high accuracy at many measurement positions on the wafer surface Wa without complicating the optical system of the AF sensor 12 so much.

  Even if the defocus amount of the slit image 37j on the wafer surface Wa and the slit image 38j on the incident surface of the deflecting prism 32 is changed by the oscillating mirror 26AD, the light beam incident on the light receiving element PEi in the light receiving element array 36 is The light beam reflected by the measurement area with the wafer surface Wa remains as it is. For this reason, the influence of the pattern formed on the wafer surface Wa or a portion having a different reflectance is reduced, and the surface position of the wafer surface Wa can be measured with high accuracy.

Further, since the defocus amount of the slit image 38j on the incident surface of the deflecting prism 32 is changed by the oscillating mirror 26AD, the mechanism for defocusing is simple. The vibrating mirror 26AD may be installed at the position of the mirror 26B in the light transmission optical system 14A of FIG.
In the present embodiment, one row of measurement areas MAi is set in the X direction in the projection area 29. However, even if a plurality of rows of measurement areas MAi are set in the projection area 29 at a predetermined pitch in the Y direction. Good. In this case, a two-dimensional image sensor may be used instead of the light receiving element array 36.

  Further, the exposure apparatus EX of the present embodiment is an exposure apparatus that illuminates the pattern of the reticle R with illumination light IL (exposure light) and exposes the wafer W with the illumination light IL via the pattern and the projection optical system PL. An AF sensor 12 and a wafer stage WST for controlling the Z position of the wafer W based on information on the Z position (surface position) of the surface of the wafer W detected by the AF sensor 12 are provided. Further, the exposure method using the exposure apparatus EX uses the Z position detected by the Z position detection method using the AF sensor 12 when the wafer W is exposed to image the surface of the wafer W on the image of the projection optical system PL. Focus on the surface.

According to the exposure apparatus EX or the exposure method of this embodiment, the Z position of the wafer surface Wa can be measured with high accuracy in many measurement areas by the AF sensor 12, and therefore the surface of the wafer W is projected optically based on this measurement value. The image plane of the system PL can be focused with high accuracy, and the pattern image of the reticle R can be exposed onto the wafer W with high accuracy.
In the exposure apparatus EX, a sensor similar to the AF sensor 12 may be used as a device for measuring the position (surface position) in the Z direction of the pattern surface of the reticle R.

[Second Embodiment]
Next, a second embodiment will be described with reference to FIG. In FIG. 7, portions corresponding to those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.
FIG. 7 shows an exposure apparatus EX according to this embodiment. Although the basic configuration of the exposure apparatus EX is the same as that of the embodiment of FIG. 1, the configuration of the AF sensor 12A (autofocus sensor or surface position detection apparatus) provided in the exposure apparatus EX is different from the AF sensor 12 of FIG. Yes. Hereinafter, the AF sensor 12A of the present embodiment will be described.

  In FIG. 7, an AF sensor 12A includes a first light source system 16A that alternately emits a first light beam LP polarized in a direction parallel to the paper surface of FIG. 7 and a second light beam LS polarized in a direction perpendicular to the paper surface of FIG. The first light beam LA and the second light beam LS in which the first light beam LP and the second light beam LS are unpolarized, respectively, are projected on the wafer surface Wa (test surface) from an oblique direction, and reflected by the wafer surface Wa. A light receiving optical system 14B for receiving the light beams LA and LB. Further, the AF sensor 12A receives the light beams LA and LB that have passed through the deflection prism 32 having a plurality of light receiving slits 33a formed on the incident surface on which the light beam received by the light receiving optical system 14B is irradiated and the light receiving slits 33a. A detection system 14C including a light receiving element array 36 having a plurality of light receiving elements, and a signal processing system for processing detection signals from the light receiving element array 36 to obtain Z positions (surface positions) of a plurality of measurement regions on the wafer surface Wa. 46.

  Further, the AF sensor 12A is disposed in the light transmission optical system 14C, and a polarization separation prism 22 (angle conversion element) made of a Wollaston prism that changes the relative angles of the first light beam LP and the second light beam LS, and A depolarization element 24 is disposed downstream of the polarization separation prism 22 and converts the first light beam LP and the second light beam LS into a non-polarized first light beam LA and a second light beam LB, respectively.

  First, the light source system 16A includes a first light source 17A1 and a second light source 17A2 made of, for example, light emitting diodes that emit unpolarized light beams L1 and L2 made of visible light and / or near infrared light having a wide wavelength range. As the light beams L1 and L2, light with low photosensitivity to the resist applied to the wafer W is preferable. The light beams L1 and L2 are incident on two orthogonal incident surfaces of the polarizing beam splitter 17C. The s-polarized light beam having a light amount of approximately ½ of the light beam L1 is reflected by the polarization beam splitter 17C and is incident on a monitoring photoelectric sensor 17D such as a photo diode, and P having a light amount of approximately ½ of the light beam L2. The polarized light beam passes through the polarization beam splitter 17C and enters the photoelectric sensor 17D. The photoelectric sensor 17D supplies the received light detection signal to the light source control system 44A. The light source control system 44 </ b> A causes the first light source 17 </ b> A <b> 1 and the second light source 17 </ b> A <b> 2 to alternately emit light with the same output instructed, for example, according to control information from the main control device 40. In the present embodiment, since the outputs of the light sources 17A1 and 17A2 are monitored by the photoelectric sensor 17D, variations in the outputs of the light sources 17A1 and 17A2 do not become measurement errors.

  On the other hand, the P-polarized first light beam LP of the light beam L1 passes through the polarizing beam splitter 17C, and the S-polarized second light beam LS indicated by the dotted line of the light beam L2 is reflected by the polarizing beam splitter 17C. The first light beam LP and the second light beam LS are converted into a substantially parallel light beam by the condenser lens 17B along substantially the same optical path, and enter the deflecting prism 18. The light beams LP and LS incident on the deflecting prism 18 are refracted by the deflecting prism 18 so that the principal ray is deflected so as to travel substantially in the −Z direction. On the exit surface of the deflecting prism 18, there is provided a light transmission slit portion 19 having a configuration in which a plurality of elongated light transmission slits 19 a are periodically arranged in a light shielding film. A light source system 16A is composed of the light sources 17A1 and 17A2, the polarizing beam splitter 17C, the condenser lens 17B, and the photoelectric sensor 17D for monitoring.

  The first light beam LP and the second light beam LS that have passed through the plurality of light transmission slits 19a of the deflecting prism 18 are incident on the first objective lens 20A of the light transmission optical system 14C. LP and LS condensed by the first objective lens 20A become a non-polarized first light beam LA and second light beam LB via the polarization separation prism 22 and the depolarizer plate (depolarizer) 24, respectively. The polarization separation prism 22 widens the relative angles of the light beams LP and LS in the direction corresponding to the X direction of the wafer surface Wa. Since the light beams LP and LS have a wide wavelength band, for example, a birefringent crystal (for example, quartz) whose thickness gradually changes can be used as the depolarization plate 24. The first light beam LA and the second light beam LB that have passed through the depolarization plate 24 bend the mirror 26A, the second objective lens 20B, and the optical path that bend the optical path in a direction inclined in the −Z direction by a predetermined angle with respect to the + X direction. The light is projected obliquely into a projection area 29 elongated in the X direction including the wafer surface Wa via the prism 28A shifted in the −Z direction. Images of a plurality of light transmission slits 19a are formed in the projection region 29 by the light beams LA and LB at a constant interval in the Y direction. Since the configuration of the light receiving optical system 14B and the detection system 14C is the same as that of the first embodiment, the description thereof is omitted.

  In the present embodiment, the light sources 17A1 and 17A2 are alternately turned on, so that the light beams LA and LB from the light transmission slit 19a are alternately projected onto the wafer surface Wa in a state where the angles are shifted in the θy direction. This operation is the same as that when the light beam is vibrated in the θy direction by the vibrating mirror 26AD in the first embodiment. That is, the defocus amount of the slit image formed on the incident surface of the deflecting prism 32 by the light sources 17A1 and 17A2 and the polarization separation prism 22 that are alternately turned on periodically changes. Therefore, a drive signal for alternately lighting the light sources 17A1 and 17A2 is supplied to the signal processing system 46, and the signal processing system 46 uses the drive signal to synchronously rectify the detection signal supplied from the light receiving element array 36. By doing so, the Z position in many measurement regions (measurement points) on the wafer surface Wa can be measured with high accuracy while reducing the influence of the base pattern and the like, as in the first embodiment.

In the present embodiment, the polarization separation prism 22 may be disposed at a position Q1 in the vicinity of a plane (pupil plane) conjugate with the exit pupil of the light receiving optical system 14B in FIG. In this case, the depolarizing plate 24 may be disposed between the position Q1 and the incident surface of the deflecting prism 32, or the depolarizing plate 24 may be omitted.
In this embodiment, since the depolarization plate 24 is disposed downstream of the polarization separation prism 22, the surface to be measured can be illuminated with a non-polarized light beam. For example, when there is no specific polarization characteristic on the test surface or the like, the depolarization plate 24 may be omitted.

In each of the above embodiments, since the prisms 28A and 28B that shift the optical path of the light beam in the Z direction are provided, the arrangement of the light transmitting optical systems 14A and 14C and the light receiving optical system 14B is easy. However, the prisms 28A and 28B are not necessarily provided.
In each of the above embodiments, the light transmission optical systems 14A and 14C and the light reception optical system 14B are a single imaging optical system. However, the light transmission optical systems 14A and 14C and / or the light reception optical system 14B are in the middle. An optical system that performs intermediate imaging may be used.

  Further, when an electronic device such as a semiconductor device is manufactured using the exposure apparatus or the exposure method of the above embodiment, the electronic device performs step 221 for performing function / performance design of the electronic device, as shown in FIG. A step 222 for producing a mask (reticle) based on the design step, a step 223 for producing a substrate (wafer) as a base material of the device, and a reticle pattern on the substrate by the exposure apparatus EX (exposure method) of the above-described embodiment. Exposure step, development step of the exposed substrate, substrate processing step 224 including heating (curing) and etching step of the developed substrate, device assembly step (including processing processes such as dicing step, bonding step, packaging step) 225 and the inspection step 226 and the like.

In other words, the device manufacturing method includes exposing a substrate (object) using the exposure apparatus or exposure method according to the above-described embodiment, and processing the exposed substrate (development or the like). It is out. In this case, since the focusing accuracy of the substrate with respect to the projection optical system PL is high, the electronic device can be manufactured with high accuracy.
The present invention can be applied to a step-and-repeat type projection exposure apparatus (stepper or the like) in addition to the above-described scanning exposure type projection exposure apparatus (scanner). Further, the present invention can be similarly applied to a dry exposure type exposure apparatus other than the immersion type exposure apparatus.

In the above embodiment, the AF sensors 12 and 12A are multi-point detection systems, but the AF sensors 12 and 12A may have only one measurement point.
The present invention is not limited to an exposure apparatus for manufacturing a semiconductor device, but is used for manufacturing a display including a liquid crystal display element and a plasma display. Applicable to exposure equipment that transfers device patterns used in ceramics onto ceramic wafers, as well as exposure equipment used to manufacture imaging devices (CCD, etc.), organic EL, micromachines, MEMS (Microelectromechanical Systems), and DNA chips. can do. Further, the present invention is applied not only to a micro device such as a semiconductor element but also to an exposure apparatus that transfers a circuit pattern to a glass substrate or a silicon wafer in order to manufacture a mask used in an optical exposure apparatus and an EUV exposure apparatus. Applicable.

  Thus, the present invention is not limited to the above-described embodiments, and various configurations can be taken without departing from the gist of the present invention.

  EX ... exposure apparatus, R ... reticle, W ... wafer, WST ... wafer stage, 12, 12A ... AF sensor (autofocus sensor), 14A, 14C ... light transmission optical system, 14B ... light reception optical system, 14C ... detection system, DESCRIPTION OF SYMBOLS 16,16A ... Light source system, 19 ... Light transmission slit part, 26AD ... Vibration mirror, 33 ... Light receiving slit part, 36 ... Light receiving element array, 40 ... Main controller, 46 ... Signal processing system

Claims (19)

In the device for detecting surface position information of the surface to be tested,
A light transmission optical system for projecting an image of a slit-like pattern in a direction along the incident surface from an oblique direction to the test surface;
A light receiving optical system that receives light reflected by the test surface and re-forms the image of the slit pattern;
An optical member having a surface on which an image of the slit-shaped pattern is re-formed, and an elongated slit-shaped opening formed along the longitudinal direction of the image of the slit-shaped pattern on the surface;
A defocus system that periodically changes the defocus amount of the image of the slit pattern on the surface on which the slit opening is formed;
A photoelectric detector for detecting light that has passed through the slit-shaped opening;
A signal processing unit for obtaining surface position information of the test surface based on a detection signal of the photoelectric detector;
A surface position detecting device comprising:   2. The defocusing system according to claim 1, wherein the defocusing system is a vibration system that vibrates a position of an image of the slit-shaped pattern in a longitudinal direction of the slit-shaped opening on a surface on which the slit-shaped opening is formed. Surface position detection device.   The vibration system is disposed on a surface conjugate with an exit pupil of the light transmitting optical system or the light receiving optical system, or in the vicinity of the surface, and determines an angle of light forming the image of the slit pattern. The surface position detecting device according to claim 2, further comprising a vibrating mirror that vibrates in a direction corresponding to a longitudinal direction of the image. The vibration system is
A light source system that supplies different first and second light beams to the light transmission optical system;
The surface position according to claim 2, further comprising: a light beam separating element that is disposed in the light transmitting optical system or the light receiving optical system and separates an optical path of the first light beam and the second light beam. Detection device. The photoelectric detector has a plurality of light receiving elements for detecting light that has passed through a plurality of openings obtained by dividing the slit-shaped opening in the longitudinal direction,
The signal processing unit processes the detection signals of the plurality of light receiving elements in synchronization with a periodic change in the defocus amount of the image of the slit pattern, and each of the plurality of light receiving elements performs the detection. The surface position detection apparatus according to claim 1, wherein the surface position information of the surface is obtained. The light transmission optical system projects a plurality of parallel images of the slit pattern on the test surface,
6. The surface position according to claim 1, wherein a plurality of slit-shaped openings are formed in the optical member corresponding to the images of the plurality of slit-shaped patterns. Detection device. The light transmission optical system is a double-sided telecentric optical system that projects an image of the slit-shaped pattern obliquely onto the test surface,
7. The both-side telecentric optical system that relays the image of the slit-shaped pattern of the test surface obliquely to the surface on which the slit-shaped opening is formed. The surface position detection apparatus as described in any one of Claims.   The surface position according to claim 1, further comprising a moving device that moves a test member having the test surface in a direction orthogonal to a longitudinal direction of the image of the slit pattern. Detection device. In an exposure apparatus that exposes a substrate with exposure light via a pattern and a projection optical system,
An exposure apparatus comprising the surface position detection device according to any one of claims 1 to 8, in order to detect a surface position of at least one of the surface on which the pattern is formed and the surface of the substrate. . In a method for detecting surface position information of a surface to be measured,
Projecting an image of an elongated slit pattern from the oblique direction to the test surface through a light transmission optical system in a direction along the incident surface,
Receiving the light reflected by the test surface through a light receiving optical system to re-form the image of the slit pattern,
The light from the light receiving optical system is detected through an elongated slit-like opening arranged along the longitudinal direction of the image of the slit-like pattern on the surface where the image of the slit-like pattern is re-formed,
Periodically changing the defocus amount of the image of the slit pattern on the surface where the slit opening is formed,
Obtaining surface position information of the test surface based on a detection signal of light from the light receiving optical system;
A surface position detection method characterized by the above.   In order to periodically change the defocus amount of the image of the slit-shaped pattern, the position of the image of the slit-shaped pattern is vibrated in the longitudinal direction of the slit-shaped opening on the surface on which the slit-shaped opening is formed. The surface position detection method according to claim 10, wherein: In order to vibrate the position of the image of the slit pattern in the longitudinal direction of the slit opening,
The angle of the light that forms the image of the slit-like pattern is determined by the vibration mirror disposed in the vicinity of the exit pupil of the light-transmitting optical system or the light-receiving optical system or in the vicinity of this surface. The surface position detecting method according to claim 11, wherein the surface position is vibrated in a direction corresponding to a longitudinal direction of the surface. In order to vibrate the position of the image of the slit pattern in the longitudinal direction of the slit opening,
Supplying different first and second light fluxes to the light transmission optical system,
12. The surface position detection method according to claim 11, wherein optical paths of the first light beam and the second light beam are separated by a light beam separation element disposed in the light transmission optical system or the light reception optical system. When obtaining the surface position information of the test surface based on the detection signal of light from the light receiving optical system,
The detection signal of light passing through a plurality of openings obtained by dividing the slit-shaped opening in the longitudinal direction is processed in synchronization with a periodic change in the defocus amount of the image of the slit-shaped pattern. Item 14. The surface position detection method according to any one of Items 10 to 13. A plurality of images of the slit pattern are projected in parallel on the test surface,
15. The light from the light receiving optical system is received through a plurality of the slit-shaped openings provided corresponding to the images of the plurality of slit-shaped patterns. The surface position detection method according to claim 1. When obtaining the surface position information of the test surface based on the detection signal of light from the light receiving optical system,
The test member having the test surface is moved in a direction orthogonal to the longitudinal direction of the image of the slit pattern, and surface position information of the test surface at a plurality of measurement points along the movement direction of the test member. The surface position detection method according to any one of claims 10 to 15, wherein: In an exposure method of exposing a substrate with exposure light via a pattern and a projection optical system,
An exposure method using the surface position detection method according to any one of claims 10 to 16, in order to detect a surface position of at least one of the surface on which the pattern is formed and the surface of the substrate. . Using the exposure apparatus according to claim 9 to transfer a mask pattern to the substrate;
Processing the substrate on which the pattern is transferred based on the pattern;
A device manufacturing method including: Using the exposure method of claim 17 to transfer a mask pattern to the substrate;
Processing the substrate on which the pattern is transferred based on the pattern;
A device manufacturing method including:

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