JP2006073932A - Focal state detecting method and its equipment, focal adjustment method and its equipment, position detecting method and its equipment, and exposing method and its equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method which can perform an alignment AF immediately without waiting for stabilizing vibration after a wafer stage 110 has transferred. <P>SOLUTION: The deviation of a wafer W with respect to the comfocal plane of an alignment sensor 117 is detected. A distance S between a polishing plate 131 on which the wafer stage 110 is mounted and a column 132, and a spacing d between the polishing plate 131 and the wafer stage 110, are measured by a Z interferometer and a linear scale. On the basis of this measuring result, the location deviation of the wafer stage 110 mounting the wafer W is calculated, and this corrects a deviation to the comfocal plane. A proper deviation can be detected even while the wafer stage 110 vibrates. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  INDUSTRIAL APPLICABILITY The present invention is applied to an alignment system that detects an alignment mark of an exposure apparatus when manufacturing an electronic device such as a semiconductor element and detects the position thereof, a focus state detection method and apparatus, and focus adjustment The present invention relates to a method and an apparatus thereof, a position detection method and an apparatus thereof, and an exposure method and an apparatus to which such a position detection method and apparatus are applied.

When manufacturing an electronic device such as a semiconductor device, a liquid crystal display device, an image pickup device such as a CCD, a plasma display device or a thin film magnetic head (hereinafter collectively referred to as an electronic device), an exposure apparatus is used to manufacture a photomask or a reticle. 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 collectively transfers the pattern formed on the reticle onto one shot area set on the photosensitive substrate. This is an exposure apparatus that sequentially moves the other shot areas by moving the steps. In addition, the scanning stepper sequentially transfers the pattern formed on the reticle to the photosensitive substrate while continuously moving (scanning) the reticle and the photosensitive substrate, and moves the photosensitive substrate after transfer to another shot area. The exposure apparatus performs scanning exposure again.

  For example, in the manufacture of semiconductor devices, a circuit pattern of a plurality of layers is formed on each shot area on a wafer as a substrate by using such an exposure apparatus, and the circuit patterns of the second and subsequent layers are projected onto the wafer. At the time of exposure, it is necessary to accurately align the pattern image of the reticle to be exposed on the pattern already formed on the wafer. That is, it is necessary to align (align) the wafer with the projection position of the pattern image of the reticle with high accuracy. As a method for detecting the position of each shot on the wafer or wafer (alignment measurement method), sample shots (hereinafter referred to as EGA shots) at several locations (three or more locations, usually, for example, 6 to 8 locations) are used. An enhanced global alignment (EGA) system that performs statistical calculation processing based on the position information measured for obtaining position information of all shot areas on the wafer has become the mainstream (see, for example, Patent Document 1).

  The wafer loaded on the wafer stage is placed on the wafer stage in a pre-aligned state, but is not positioned at a level (accuracy) at which EGA measurement as fine alignment can be performed. Therefore, so-called search alignment is generally performed in which the wafer position is roughly adjusted before the EGA measurement is performed so as not to hinder the EGA measurement. In the search alignment, the position of an alignment mark (search alignment mark) is detected in a shot area designated in advance (for example, two locations, hereinafter referred to as a search shot), and the coordinate value of the shot area is corrected based on the detection result. Is.

  In addition, when measuring the alignment mark in the EGA or search alignment as the fine alignment described above, an imaging surface (focusing surface) of the alignment optical system is formed on the mark forming surface on the wafer in order to obtain a clear image of the object. ) Must match. Therefore, for example, alignment AF (autofocus) is performed to detect the relative position of the wafer with respect to the imaging plane of the optical system and adjust the height of the wafer stage, for example, so that they match. As a method of detecting the relative position between the imaging plane of the optical system and the wafer surface, the wafer surface is illuminated with a slit-shaped light beam, and the light beam from the illuminated wafer is divided into pupils on the pupil surface of the objective optical system. A so-called pupil division method is known in which the relative positions of the imaging plane and the wafer surface in the optical axis direction are detected based on the position of the luminous flux obtained by pupil division (see, for example, Patent Document 2).

By the way, in the exposure process in the manufacturing process of an electronic device, the improvement of a throughput is conventionally requested | required and there exists a request | requirement of performing an alignment process efficiently in a short time. As a method for this, for example, in a series of alignment processes including search alignment and EGA measurement as fine alignment described above, the order of shots for alignment measurement is optimized in consideration of the positional relationship between search shots and EGA shots. Thus, there has been proposed a position measurement method that reduces the movement distance between shots and shortens the time required to measure a plurality of marks (see, for example, Patent Document 3).
JP-A 61-44429 JP-A-8-167550 JP 2001-135559 A

  When wafer alignment is performed by the FIA system in such an exposure apparatus, as described above, for each wafer, alignment mark position measurement such as two search measurements and eight EGA measurements (fine measurement) is performed. Will do. Accordingly, the position of the wafer stage (wafer) is sequentially moved about 10 times, and alignment AF and mark position measurement are performed at each position.

  At this time, the movement of the wafer stage causes a phenomenon that the wafer stage slightly vibrates even after the wafer stage is stopped. In such a state, accurate focus state measurement and position measurement cannot be performed. For this reason, immediately after the wafer stage is moved (a predetermined period after the stop), the subsequent stage measurement is performed after waiting for the vibration of the wafer stage to settle (converge). That is, immediately after the movement of the wafer stage, the measurement process is not performed immediately, but the measurement is performed after waiting for a certain period of time and the vibration is settled.

However, it is not preferable to require such a waiting time while it is desired to improve the throughput as much as possible in the alignment process.
Actually, as a specific example, for example, in an exposure apparatus that performs position measurement of about 8 points on a wafer in a time of about 3 seconds, a standby time from the end of movement of the wafer stage until the stage is settled. As (time until measurement is started), a time of about 10 msec to 20 msec per measurement location may be required. Therefore, 80 msec to 160 msec out of about 3 seconds required for measuring the position of the EGA shot is spent in the waiting time for stabilization after the stage is moved, and is not negligible.

The present invention has been made in view of such problems, and an object of the present invention is to immediately detect the focus state of the alignment system without waiting for the vibration of the wafer stage to settle after moving the wafer stage. An object of the present invention is to provide a focus state detection method and apparatus capable of the same.
Another object of the present invention is to adjust the focus state based on the focus state detection result so that the focus state of the alignment system can be quickly adjusted even after the wafer stage is moved and the apparatus. Is to provide.

Another object of the present invention is to quickly detect the position after moving the wafer stage by detecting the position of a desired portion of an object such as a wafer after performing such focus adjustment. It is an object of the present invention to provide a position detection method and an apparatus for the same.
Furthermore, another object of the present invention is to apply such a position detection method and apparatus so that the alignment measurement for the wafer can be efficiently performed in a short time, and the exposure process can be performed at a high throughput. And providing such a device.

  In order to solve the above-described problem, a focus state detection method according to the present invention includes a focus detection surface of a position detection optical system that detects the position of an object placed on a stage in a focal direction of the position detection optical system. A focus state detection method for detecting a focus state of the object, wherein the amount of deviation of the object with respect to the in-focus plane is detected by irradiating the object with detection light and detecting reflected light of the detection light. Simultaneously with the detection of the shift amount, position information of the stage in the focal direction is detected, and the focus state of the object is calculated by correcting the shift amount based on the position information. ).

  In the focus state detection method having such a configuration, the detection of the position information of the stage on which the object is placed in the focal direction is detected simultaneously with the detection of the deviation of the focus direction of the object such as the wafer (displacement with respect to the in-focus plane). The amount of displacement of the object is corrected by the stage position information. Accordingly, even when the stage vibrates, for example, the displacement of the stage position due to the vibration is corrected immediately, so that the correct amount of displacement of the object can always be detected.

  In the focus adjustment method according to the present invention, based on the focus state detected by the focus state detection method described above, the position of the object in the focal direction matches the in-focus plane of the position detection optical system. In addition, the position of the stage in the focal direction is adjusted.

In the position detection method according to the present invention, the position detection optical system detects the position of a predetermined location on the object, the position of the focus direction of which has been adjusted by the focus adjustment method described above.
Preferably, the position of the predetermined position of the object is detected by the position detection optical system in a state where the stage on which the object is placed is stationary.

  Also preferably, there is provided a method for detecting a position of a desired pattern formed on the substrate as the object, wherein the pattern formed on the substrate falls within a detection visual field of the position detection optical system. Immediately after the stage is moved and the substrate is moved, the pattern region on the substrate arranged in the detection visual field of the position detection optical system is focused on the position detection optical system by the focus adjustment method described above. The position of the stage in the focal direction is adjusted so as to coincide with a plane, and the position of the focal direction is orthogonal to the focal direction of the pattern formed on the substrate placed on the stage. A position in a two-dimensional plane is detected by the position detection optical system.

  Preferably, the detection of the amount of shift in the focal direction with respect to the focal plane of the position detection optical system of the pattern region of the substrate and the detection of positional information of the stage in the focal direction are performed by the stage of the stage. Immediately after the movement, the stage vibration associated with the movement is not converged (Claim 6).

  Further, the exposure method according to the present invention detects the position of the position measurement target pattern formed on the substrate placed on the stage by any of the position detection methods described above, and based on the detected position. Then, the substrate is aligned, and a predetermined pattern is transferred and exposed on the aligned substrate.

  Further, the focus state detection device according to the present invention indicates the focus state of the object in the focal direction of the position detection optical system with respect to a focal plane of the position detection optical system that detects the position of the object placed on the stage. A focus state detection device for detecting a displacement amount detecting means for detecting a displacement amount of the object with respect to the in-focus plane by irradiating the object with detection light and detecting reflected light of the detection light. 117, 231, 239), stage position detection means (261, 262, 269) for detecting position information of the stage in the focal direction simultaneously with detection of the shift amount, and the shift amount based on the position information. And a focus state calculation means (280) for calculating the focus state of the object by correcting the image (Claim 8).

  In addition, the focus adjustment device according to the present invention is configured such that the position of the object in the focus direction of the position detection optical system is based on the focus state detection device described above and the focus state detected by the focus state detection device. Stage position adjusting means for adjusting the position of the stage in the focal direction so as to coincide with the in-focus plane (claim 9).

The position detection device according to the present invention includes the focus adjustment device described above, and the position detection optical system that detects a position of a predetermined location on the object whose position in the focus direction is adjusted by the focus adjustment device. (Claim 10).
Preferably, the position of the predetermined position of the object is detected by the position detection optical system while the stage on which the object is placed is stationary.

  Preferably, the position detection device detects a position of a desired pattern formed on the substrate as the object, and the pattern formed on the substrate falls within a detection visual field of the position detection optical system. A stage moving means for moving the stage to a position immediately after the substrate is moved, and a pattern area on the substrate arranged in a detection field of the position detection optical system is a focal plane of the position detection optical system. The focus adjustment device described above for adjusting the position of the stage in the focal direction so as to match, and the pattern of the pattern formed on the substrate placed on the stage in which the position of the focus direction is adjusted The position detection optical system detects a position in a two-dimensional plane orthogonal to the focal direction.

  Preferably, the shift amount detection means detects the shift amount in the focal direction of the pattern area of the substrate with respect to the focal plane of the position detection optical system, and the stage position detection means causes the focus of the stage. The position information in the direction is detected immediately after the stage is moved by the stage moving means in a state where the vibration of the stage accompanying the movement has not converged (Claim 13).

  An exposure apparatus according to the present invention includes any one of the position detection apparatuses described above that detects the position of a pattern of a position measurement target formed on a substrate placed on a stage and aligns the substrate. Exposure means for transferring and exposing a predetermined pattern on the aligned substrate (claim 14).

According to the present invention, it is possible to provide a focus state detection method and apparatus capable of immediately detecting the focus state of the alignment system without waiting for the vibration of the wafer stage to settle after moving the wafer stage.
Further, by adjusting the focus state based on the focus state detection result, it is possible to provide a focus adjustment method and apparatus capable of quickly adjusting the focus state of the alignment system even after the wafer stage is moved.

Further, a position detection method and apparatus capable of quickly detecting the position after moving the wafer stage by detecting the position of a desired part of an object such as a wafer after performing such focus adjustment. Can be provided.
Furthermore, by applying such a position detection method and apparatus, it is possible to provide an exposure method and apparatus capable of performing alignment measurement on a wafer efficiently in a short time and performing exposure processing with high throughput. it can.

An embodiment of the present invention will be described with reference to FIGS.
In the present embodiment, the present invention is described by describing an exposure apparatus that projects and transfers an image of a circuit pattern formed on a reticle onto a plurality of shot areas on a wafer via a projection optical system, and an alignment system thereof. explain.

First, the overall configuration of the main part of the exposure apparatus will be described.
FIG. 1 is a view showing a schematic configuration of the exposure apparatus 100.
In the exposure apparatus 100, illumination light emitted from a light source 102 such as an ultra-high pressure mercury lamp or an excimer laser is reflected by a reflecting mirror 103 and is incident on a wavelength selection filter 104 that transmits only light having a wavelength necessary for exposure. . The illumination light transmitted through the wavelength selection filter 4 is adjusted to a light beam having a uniform intensity distribution by an optical integrator (fly eye lens or rod) 105 and reaches a reticle blind (field stop) 106. The reticle blind 106 sets the illumination area on the reticle R by illumination light by changing the size of the opening S by driving a plurality of blades by the drive system 106a.

  The illumination light that has passed through the opening S of the reticle blind 106 is reflected by the reflecting mirror 107 and enters the lens system 108. The lens system 108 forms an image of the opening S of the reticle blind 106 on the reticle R held on the reticle stage 120, and illuminates a desired pattern area of the reticle R. The wavelength selection filter 104, the optical integrator 105, the reticle blind 106, and the lens system 108 constitute an illumination optical system of the exposure apparatus 100.

Reticle stage 120 can move two-dimensionally in a plane perpendicular to the optical axis of projection optical system 109. The position and rotation amount of reticle stage 120 (reticle R) are detected by a laser interferometer (not shown), and the position information of reticle stage 120 (reticle R), which is a measurement value thereof, includes stage control system 114, main control system 115, and Each is output to the alignment control system 119.
An image of a circuit pattern or alignment mark existing in the illumination area of the reticle R is formed on the wafer W coated with a resist by the projection optical system 109. As a result, the pattern image of the reticle R and the alignment mark image are exposed to the shot area on the wafer W placed on the wafer stage 110.

  The wafer stage 110 has a wafer holder (not shown) that vacuum-sucks the wafer W, and is moved in the X and Y directions perpendicular to the optical axis of the projection optical system 109 and perpendicular to each other by a drive device 111 such as a linear motor. . As a result, the wafer W is two-dimensionally moved on the image plane side with respect to the projection optical system 109. The pattern image of the reticle R is transferred onto the shot area.

  Further, the position of the wafer stage 110 (wafer W) on the stage movement coordinate system XY in the X and Y directions and the rotation amount (yaw amount, pitching amount, rolling amount) are provided at the end of the wafer stage 110. It is detected by a laser interferometer 113 that irradiates the moving mirror (reflecting mirror) 12 with laser light. Measurement values (position information) of the laser interferometer 113 are output to the stage control system 114, the main control system 115, and the alignment control system 119, respectively.

  The stage control system 114 controls the movement of the reticle stage 120 and the wafer stage 110 via the driving device 111 and the like based on position information from the main control system 115 and the laser interferometer 113 and the like.

The main control system 115 performs control of the size and shape of the opening S of the reticle blind 106 via the drive system 106a, EGA calculation based on the position information of the alignment mark on the wafer W output from the alignment control system 119, etc. Overall control of the exposure apparatus 100 is performed.
The main control system 115 is connected to an input unit 121 for inputting various exposure data. As exposure data, each position of a shot area, a position of a search shot, a position of an EGA shot, a position of a search mark, a position of a fine mark (EGA mark), and the like are input.

  The exposure apparatus 100 includes, for example, a TTR (through-the-reticle) type reticle alignment sensor 116 and an off-axis type wafer alignment sensor 117 in order to align the reticle R and the wafer W. Yes.

The reticle alignment sensor 116 is an alignment system of an exposure light alignment system, and detects a reference mark on the reference mark member 118 via the reticle R and the projection optical system 109 using exposure illumination light, and on the reticle R. The image of the alignment mark (reticle / alignment mark) and the reference mark formed in (1) is picked up by an image pickup device (CCD), and the image pickup signal is output to the alignment control system 119. Thereby, the positional relationship between the reticle alignment mark and the reference mark can be directly observed.
The reference mark member 118 is fixed on the wafer stage 110, and a reference mark is formed at the same height as the surface of the wafer W.

  With respect to the reticle alignment sensor 116, the alignment control system 119 detects the amount of misalignment between the marks based on the image signals of the reticle alignment mark and the reference mark input from the reticle alignment sensor 116. Further, based on the position measurement value of wafer stage 110 and the position measurement value of reticle stage 120 input from laser interferometer 113 or the like, reticle stage 120 and wafer when the amount of positional deviation between both marks is 0 (zero). Each position of the stage 110 is obtained. As a result, the position of the reticle R on the wafer stage movement coordinate system XY is detected. In other words, the reticle stage movement coordinate system and the wafer stage movement coordinate system XY are associated (detection of relative positional relationship). The alignment control system 119 outputs the resulting position information to the main control system 115.

  The wafer alignment sensor 117 is an FIA (Field Image Alignment) type alignment system. The wafer alignment sensor 117 is provided with illumination light in a wavelength range that does not expose the resist on the wafer W via an objective optical system that is provided separately from the projection optical system 109, for example, broadband light having a wavelength of about 530 to 800 nm (broadband light). Light) is applied to an alignment mark (wafer alignment mark) on the wafer W, and an image of the alignment mark is formed on the light receiving surface of the image sensor (CCD) through the objective optical system. An image pickup signal (photoelectric conversion signal, image signal) is output to the alignment control system 119.

  The wafer alignment sensor 117 has an AF (autofocus) function. The AF function of the wafer alignment sensor 117 includes a focus state detection unit that detects a focus state of illumination light on the alignment arc forming surface on the wafer W, and an optical axis of the objective optical system of the wafer alignment sensor 117. And a focus adjustment unit that adjusts the alignment mark forming surface on the wafer W to coincide with the focal plane of the objective optical system. The focus state detection unit illuminates the wafer surface with, for example, a slit-shaped light beam, divides the light beam from the illuminated wafer by the pupil plane of the objective optical system, and forms an image plane based on the position of the pupil-divided light beam And a so-called pupil division type detector that detects the relative positions of the wafer surface in the optical axis direction.

  Further, the wafer alignment sensor 117 has two separate (one) optical system for search alignment (search measurement) and one optical system for fine alignment (EGA measurement) for one objective lens for observing the wafer W. Part of the optical system. That is, observation light (reflected light) obtained by irradiating illumination light to a predetermined location on the wafer W through one objective lens is sent to the search optical system or the fine optical system in the wafer alignment sensor 117. It is configured to enter.

Although the search optical system has a lower magnification than the fine optical system, it can observe the wafer W in a wide visual field range, and the fine optical system has a narrow visual field range than the search optical system. The wafer W can be observed at a high magnification. Each optical system includes a two-dimensional image sensor, and is configured to capture an image of each observation field. An image signal (photoelectric conversion signal) imaged by each image sensor via these optical systems is output to the alignment control system 119.
The observation visual field of the search optical system and the fine optical system of the wafer alignment sensor 117 will be described in detail with reference to the drawings in the description of the signal processing system related to wafer alignment described later.

  With respect to the wafer alignment sensor 117, the alignment control system 119 is arranged in the fine optical system based on the imaging signal from the wafer alignment sensor 117, for example, during fine alignment measurement. The amount of positional deviation between the reference mark and the alignment mark (wafer alignment mark) is detected. Further, with reference to the position measurement value of wafer stage 110 input from laser interferometer 113, the position of wafer stage 110 when the amount of positional deviation is 0 (zero) is indicated on wafer stage movement coordinate system XY. Obtained as the coordinate value of the alignment mark. Then, alignment control system 119 outputs the position information to main control system 115.

  The main control system 115 gives a command such as a signal processing condition to the alignment control system 119, and also performs search measurement and fine measurement (EGA) based on the alignment mark position information (coordinate values) output from the alignment control system 119. (Calculation). Further, the main control system 115 controls the position of the wafer W and the transfer of the pattern image of the reticle R to each shot area of the wafer W based on the measured alignment mark position information.

  Specifically, the main control system 115 measures the positions of alignment marks (search alignment marks) in, for example, two search shot areas designated in advance, so that EGA measurement can be performed based on the measurement results. The position of the wafer W is adjusted. Further, the positions of alignment marks (fine alignment marks) in, for example, six EGA shot areas designated in advance on the wafer W whose position has been adjusted by the search alignment are measured, and all the positions on the wafer W are measured based on the measurement result. A coordinate value of the position of the shot area (for example, the position of a reference point such as a shot center) is calculated.

The main control system 115 corrects the calculated coordinate value based on the baseline amount of the wafer alignment sensor 117 and outputs the corrected coordinate value to the stage control system 114.
The stage control system 114 controls the movement of the wafer stage 10 via the driving device 11 based on the position information from the main control system 115.
Then, under the control of the main control system 115, the pattern image of the reticle R is transferred to each shot area on the wafer W by, for example, the step-and-repeat method (or step-and-scan method).
The overall configuration of the exposure apparatus 100 has been described above.

Next, the wafer W used in the exposure apparatus 100 having such a configuration and the alignment marks formed on the wafer W will be described with reference to FIGS.
2 is a view showing an example of a shot region used for alignment on the wafer W used in the exposure apparatus 100, and FIG. 3 is a view for explaining the observation field of the mark M to be subjected to alignment measurement and the wafer alignment sensor 117. FIG.
A plurality of shot regions are arranged in a matrix on the wafer W used in the exposure apparatus 100, and a circuit pattern is formed in each shot region by exposure and development in the previous process. In the present embodiment, as shown in FIG. 2, with respect to these shot regions, eight search shot regions SS1 and SS2 and six fine alignment (EGA) shot regions ES1 to ES6 are provided at eight locations. The shot area is set as a position measurement target shot area.

  These shot areas SS1, SS2, and ES1 to ES6 that are alignment measurement targets have the same mark in the search measurement and fine measurement (EGA measurement) as shown in FIG. 3 outside the pattern areas. The alignment mark M used for both the position measurement in the X direction and the position measurement in the Y direction is formed. The alignment mark M is a two-dimensional direction measurement mark whose measurement direction is the X direction and the Y direction.

In such wafer W and each alignment mark M, in the wafer alignment processing according to the present invention described in detail later, first, the alignment mark M associated with the first search shot area SS1 and the second search mark. The wafer stage 110 is sequentially moved so that the alignment mark M associated with the shot area SS2 is arranged in the observation field of view VS (see FIG. 3) of the wafer alignment sensor 117 at the time of search measurement. Search alignment is performed by performing alignment AF and sequentially measuring the position of the mark.
Further, based on the result of the search alignment, the alignment marks M associated with the first EGA shot area ES1 to the sixth EGA shot area ES6 are in the observation visual field VF of the wafer alignment sensor 117 at the time of EGA measurement. The wafer stage 110 is sequentially moved so as to be arranged, alignment AF is performed at each moved position, the positions of the marks are sequentially measured, and the positions of all shot areas on the wafer W are detected based on the position measurement results. EGA measurement is performed.

  In the alignment process according to the present invention, when performing these search alignments or EGA measurements, the wafer stage 110 is arranged such that the alignment mark M associated with each shot area is arranged in the observation field VS or VF of the wafer alignment sensor 117. This method is characterized in the timing of performing alignment AF immediately after moving and the method of alignment AF.

Next, referring to FIG. 4 for the relative positional relationship between the wafer alignment sensor 117 and the wafer stage 110 and the focus state detection method of the wafer alignment sensor 117 according to the present invention in the exposure apparatus 100 having such a configuration. To explain.
FIG. 4 is a view for explaining the installation status of the wafer stage 110, the projection optical system 109, and the wafer alignment sensor 117 of the exposure apparatus 100 and their relative positional relationship.
As shown in FIG. 4, the wafer stage 110 is placed and installed on a surface plate 131. The projection optical system 109 and the wafer alignment sensor 117 are installed in the column 132. The surface plate 131 and the column 132 are each installed with respect to the frame of the exposure apparatus 100 via the active vibration isolator 140, and are each maintained at a predetermined reference position. Further, the surface plate 131, the projection optical system 109, and the wafer alignment sensor 117 are installed on the surface plate 131 and the column 132, respectively, and are maintained at predetermined reference positions.
In FIG. 4, the XYZ axes are defined as shown. In this case, the positive direction in the Z direction is the vertically upward direction in the real space.

In such an installation state of each component, the distance S between the upper surface of the surface plate 131 and the lower surface of the column 132 is measured by the Z interferometer 261 in FIG. The distance d from the bottom surface is measured by the linear scale 262. Further, it can be considered that the thickness a of the wafer stage 110 is maintained at a constant value. Accordingly, the distance between the wafer alignment sensor 117 and the upper surface of the wafer stage 110 is the measured value of the distance S by the Z interferometer 261, the measured value of the distance d by the linear scale 262, and a fixed value of the thickness a of the wafer stage 110. Can be calculated based on
Normally, the distance between the wafer alignment sensor 117 and the wafer stage 110 is maintained at a predetermined reference interval. For example, during alignment measurement, the wafer stage 110 moves on the surface plate 131 and moves in the Z direction. This distance will fluctuate if it vibrates. However, this variation, that is, the relative shift amount of the distance between the wafer alignment sensor 117 and the wafer stage 110 can be calculated from the measurement results of the Z interferometer 261 and the linear scale 262 as described above.

Therefore, in the focus state detection method according to the present invention, the wafer alignment sensor 117 simultaneously measures the shift amount Δz of the wafer W placed on the wafer stage 110 with respect to the focal plane of the optical system of the wafer alignment sensor 117. At the same time, the distance S between the column 132 and the surface plate 131 and the distance d between the surface plate 131 and the wafer stage 110 are measured by the Z interferometer 261 and the linear scale 262, respectively.
Thus, since the displacement amount of the wafer stage 110 can be calculated from the distance S and the interval d, the focus shift amount Δz detected by the wafer alignment sensor 117 is corrected by the displacement amount of the wafer stage 110. As a result, the amount of defocus of the wafer alignment sensor 117 with respect to the state where the wafer stage 110 is at the reference position, that is, the state where the vibration of the wafer stage 110 has settled after a sufficient time has elapsed after the wafer stage 110 has moved. Can be detected.

Next, the configuration of a signal processing system (hereinafter referred to as a wafer alignment system) relating to wafer alignment of the exposure apparatus 100 that performs such processing will be described with reference to FIG.
FIG. 5 is a diagram showing the configuration of the wafer alignment system 200.
As shown in FIG. 5, the wafer alignment system 200 includes two search cameras 211 and 212 (to be described later), a search unit 219, three fine cameras 221 to 223 (to be described later), a fine unit 229, and one focus camera. 231, focus unit 239, position monitor unit 240, Z interferometer 261, linear scale 262, other sensor units 269, data communication optical transmission line (optical fiber) 270, monitor video output line 271, position data communication light A transmission path 272, a focus signal accumulation control line 273, a signal processing unit 280, and a monitor 290 are included.

  The search system cameras 211 and 212, the search unit 219, the fine system cameras 221 to 223, the fine unit 229, the focus camera 231, the focus unit 239, and the other sensor units 269 shown in FIG. The apparatus 100 constitutes a wafer alignment sensor 117. Further, the position monitor unit 240 is included in the stage control system 114 in FIG. Further, the signal processing unit 280 is shown as one control unit in which the alignment control system 119 and the main control system 115 in FIG. 1 are combined.

In the wafer alignment system 200 shown in FIG. 5, the two search system cameras 211 and 212 are the search camera 211 and the observation camera 212.
The search camera 211 observes a desired search mark detection area of the wafer W in an observation visual field VS as shown in FIG. 3 at a predetermined magnification, and outputs a video signal (video signal) to the search unit 219. It is a camera.

  As shown in FIG. 3, the observation field of view VS of the search camera 211 can sufficiently absorb the alignment error due to the wafer pre-alignment of the alignment mark M to be measured (alignment process performed before placing the wafer on the wafer stage). It is a large area. Moreover, it is an area | region wider than the observation visual field VF in the case of the fine measurement mentioned later. However, the observation magnification of the search camera 211 is lower than the observation magnification of an X-direction measurement fine camera 221 and a Y-direction measurement fine camera 222 described later. The arrangement of the observation region VS on the wafer W is set by controlling the position of the wafer W via the driving device 111 by the main control system 115 and the stage control system 114.

  The observation camera 212 is a camera for observing the wafer W with a wider field of view than the search camera 211 for assistance and adjustment.

  The search unit 219 is a control unit for the search camera 211 and the observation camera 212, and is an interface unit between the search system cameras 211 and 212 and the signal processing unit 280. Control signals for the search camera 211 and the observation camera 212 are input from the signal processing unit 280 to the search unit 219 via the data transmission path 270. The search unit 219 outputs this to the search camera 211 and the observation camera 212. Thereby, the search camera 211 and the observation camera 212 are each controlled to a desired operation.

The search unit 219 captures an image at a desired timing from the video signal (analog video signal) input from the search camera 211 and the observation camera 212 based on the control signal input from the signal processing unit 280. The image signal is AD converted to a digital image signal, and then sent to the signal processing unit 280 via the data communication optical transmission line 270.
At that time, the search unit 219 performs encoding processing (signal processing) such as compression of the digital image signal based on the control signal from the signal processing unit 280, and then the encoded signal is processed. The data is transmitted to the signal processing unit 280 via the data communication optical transmission line 270.

  Further, the search unit 219 outputs the video signal (analog video signal) input from the search camera 211 and the observation camera 212 to the monitor 290 via the monitor video output line 271. In the present embodiment, it is assumed that video signals are output from the search camera 211 and the observation camera 212 to the monitor 290 independently. The search unit 219 controls the output of each video signal to the monitor 290 based on a selection signal input via a signal line (not shown) based on an operator's selection operation. As a result, the observation video or the captured image from the search camera 211 or the observation camera 212 is displayed on the monitor 290 for confirmation by an operator, for example.

The three fine cameras 221 to 223 of the wafer alignment system 200 are an X direction measuring fine camera 221, a Y direction measuring fine camera 222, and an index mark measuring camera 223.
The X direction measurement fine camera 221 and the Y direction measurement fine camera 222 observe the desired fine mark detection region of the wafer W at a predetermined magnification in the observation visual fields VFX and VFY, respectively, as shown in FIG. This is a two-dimensional CCD camera that outputs a signal (video signal) to the fine unit 229.

The X direction measurement fine camera 221 images the inside of the observation visual field VFX with the X direction as the scanning direction (scanning line direction), and the Y direction measurement fine camera 222 has the Y direction as the scanning direction (scanning line direction). The inside of VFY is captured. In this embodiment, the observation visual field VFX of the X-direction measurement fine camera 221 and the observation visual field VFY of the Y-direction measurement fine camera 222 are the same observation visual field (observation visual field VF). It is also possible to set different regions so as to exclude any components that are invalid for measurement in each direction.
Note that the observation magnification of the X-direction measurement fine camera 221 and the Y-direction measurement fine camera 222 is higher than the observation magnification of the search camera 211 described above. The range of the observation visual field VF of the X direction measurement fine camera 221 and the Y direction measurement fine camera 222 is narrower than the observation visual field VS of the search camera 211.

As shown in FIG. 3, the observation visual fields VFX and VFY are regions narrower than the observation visual field VS at the time of search measurement.
The arrangement of the observation visual field VF on the wafer W is set by controlling the position of the wafer W via the driving device 111 by the main control system 115 and the stage control system 114.

  The index mark measurement camera 223 is a camera for detecting a reference index mark attached to the tip of the objective lens of the FIA optical system. If the objective lens of the wafer alignment sensor 117 undergoes positional fluctuations due to environmental conditions such as temperature or atmospheric pressure, mechanical positional fluctuations for some reason, vibration or drift, etc., the wafer alignment sensor 117 The image to be observed seems to have moved. In order to cancel such a change in position, an index mark is attached to the tip of the objective lens, and the index mark measuring camera 223 detects the position of the index mark. In addition, when measuring this index mark, a dedicated infrared detection light is used. An infrared light cut filter is provided immediately before the other cameras 211, 212, 221, 222, and 231 so that infrared light irradiated on the index mark and reflected on the mark is not detected except by the index camera 223. It has been.

  The fine unit 229 is a control unit for the X-direction measurement fine camera 221 to the index mark measurement camera 223 and is an interface unit between the fine system cameras 221 to 223 and the signal processing unit 280. Control signals from the X direction measurement fine camera 221 to the index mark measurement camera 223 are input to the fine unit 229 from the signal processing unit 280 via the data communication optical transmission path 270. The fine unit 229 outputs this to the cameras 221 to 223. Thereby, the X direction measurement fine camera 221 to the index mark measurement camera 223 are each controlled to a desired operation.

Further, the fine unit 229 performs a desired timing based on a control signal input from the signal processing unit 280 from a video signal (analog video signal) input from the X direction measuring fine camera 221 to the index mark measuring camera 223. Import the images. The image signal is AD converted to a digital image signal, and then sent to the signal processing unit 280 via the data communication optical transmission line 270.
At that time, the fine unit 229 performs encoding processing (signal processing) such as compression of the digital image signal as necessary based on the control signal from the signal processing unit 280, and then the encoded signal is processed. The data is transmitted to the signal processing unit 280 via the data communication optical transmission line 270.

  The fine unit 229 receives video signals (analog video signals) input from the X direction measurement fine camera 221, the Y direction measurement fine camera 222, and the index mark measurement camera 223 via the monitor video output line 271. Output to the monitor 290. In the present embodiment, it is assumed that video signals are output independently from each of the fine cameras 221 to 223 to the monitor 290. The fine unit 229 controls the output of each video signal to the monitor 290 based on a selection signal input via a signal line (not shown) based on an operator's selection operation. As a result, images captured by the fine cameras 221 to 223 are displayed on the monitor 290 for confirmation by, for example, an operator.

  The focus camera 231 of the wafer alignment system 200 detects the relative positional relationship of the surface of the wafer W with respect to the imaging plane of the illumination light in the optical axis direction (focus direction) of the illumination light of the wafer alignment sensor 117. This is a CCD camera for detecting a light beam incident on the surface of the wafer W from an oblique direction.

The focus unit 239 is a control unit of the focus camera 231 and an interface unit between the focus camera 231 and the signal processing unit 280. The focus unit 239 controls the focus camera 231 based on a control signal input from the signal processing unit 280 via the data communication optical transmission path 270.
The focus unit 239 also receives a control signal input from the signal processing unit 280 from a video signal (analog video signal) input from the focus camera 231 or a focus signal accumulation control line 273 from the position monitor unit 240. The image from the focus camera 231 is fetched as the focus information based on the focus information accumulation instruction signal input in the above manner. The image signal is AD converted to a digital image signal, and then sent to the signal processing unit 280 via the data communication optical transmission line 270.
At that time, the focus unit 239 performs encoding processing (signal processing) such as compression of a digital image signal based on a control signal from the signal processing unit 280, and then converts the encoded signal into a signal. The data is transmitted to the signal processing unit 280 via the data communication optical transmission line 270.

  Further, the focus unit 239 outputs the video signal (analog video signal) input from the focus camera 231 to the monitor 290 via the monitor video output line 271. The fine unit 229 controls the output of each video signal to the monitor 290 based on a selection signal input via a signal line (not shown) based on an operator's selection operation. As a result, an image captured by the focus camera 231 is displayed on the monitor 290 for confirmation by, for example, an operator.

The position monitor unit 240 sends interferometer data (position coordinate information) indicating the position of the wafer stage 110 input from the laser interferometer 113 to the signal processing unit 280 via the optical transmission path 272 for position data communication.
Further, the position monitor unit 240 monitors the interferometer data, and the position coordinate value of the wafer stage 110 becomes equal to the focus signal accumulation position preset by the signal processing unit 280 via a control line (not shown). In this case, a signal instructing accumulation of focus information is output to the focus unit 239 via the focus signal accumulation control line 273.

  As described with reference to FIG. 4, the Z interferometer 261 is an interferometer that measures the distance S between the surface plate 131 and the column 132.

  The linear scale 262 is an interferometer that measures the distance between the surface plate 131 and the wafer stage 110 as described with reference to FIG.

Each of the other sensor units 269 is an interface unit with other sensors other than the search system cameras 211 and 212, the fine system cameras 221 to 223, and the focus camera 231. For example, the Z interferometer 261, the linear scale 262, and the like are connected. Is done.
The control signals of these sensors are input from the signal processing unit 280 to the other sensor units 269. Each of the other sensor units 269 outputs this to each sensor. Thereby, each sensor is controlled to a desired operation.
Each of the other sensor units 269 sends a signal input from each connected sensor to the signal processing unit 280 via the data transmission path 270. Each of the other sensor units 269 takes in a signal from each sensor at a desired timing based on a control signal input from the signal processing unit 280, and AD-converts the signal to send it to the signal processing unit 280 as a digital signal. To do.

  Further, when the input signal from the connected sensor is a video signal, each of the other sensor units 269 outputs the video signal to the monitor 290 via the monitor video output line 271. Each of the other sensor units 269 controls output of the video signal to the monitor 290 based on a selection signal input via a signal line (not shown) based on an operator's selection operation.

The data communication optical transmission line 270 is a transmission unit that connects the search unit 219, the fine unit 229, the focus unit 239, the other sensor units 269, and the signal processing unit 280. In the present embodiment, the data communication optical transmission line 270 is a high-speed digital optical signal transmission line such as an optical link configured using an optical fiber as a transmission medium, that is, an optical communication network.
The optical transmission line for data communication 270 includes a search unit 219, a fine unit 229, a focus unit 239, other sensor units 269, and a signal processing unit 280 (these components connected to the optical transmission line for data communication 270 are nodes. Are collectively connected in a loop. Each of these nodes includes a bus controller that controls transmission / reception of data on the optical transmission line 270 for data communication, and these controllers sequentially transmit, receive, or relay data packets, A desired data packet is transmitted and received between arbitrary nodes.

Digital signals such as image signals and sensor output signals are transmitted from the search unit 219, the fine unit 229, the focus unit 239, and the other sensor units 269 to the signal processing unit 280 via the data communication optical transmission path 270 having the above configuration. Data is transmitted.
In this embodiment, commands, parameters, and the like are transferred from the signal processing unit 280 to the search unit 219, the fine unit 229, the focus unit 239, and other sensor units 269 through the data communication optical transmission line 270. Is done through.

  The monitor video output line 271 is a transmission system for transmitting a monitor video signal from the search unit 219, the fine unit 229, the focus unit 239, and other sensor units 269 to the monitor 290.

  The optical transmission path 272 for position data communication is a transmission means for transmitting the interferometer data of the laser interferometer 113 from the position monitor unit 240 to the signal processing unit 280. Like the optical transmission path 270, an optical fiber is used as a transmission medium. A high-speed digital optical signal transmission path such as an optical link configured as described above, that is, an optical communication network.

  The signal processing unit 280 is a control unit that controls each unit of the exposure apparatus 100. As processing related to the wafer alignment system 200, the signal processing unit 280 is based on imaging signals such as alignment marks input via the search system cameras 211 and 212, the fine system cameras 221 to 223, and the focus camera 231. A one-dimensional signal waveform in the desired direction of the mark is detected. Further, processing for detecting the position of the mark is performed based on the signal waveform of the mark. Further, based on the position measurement results of six EGA shots on the wafer, EGA calculation processing is performed to calculate the positions of all shot areas on the wafer by calculation statistical processing.

  Prior to the measurement of the mark positions, the signal processing unit 280 performs alignment AF. In the exposure apparatus 100, alignment AF is performed when the wafer stage 110 is moved so that the alignment mark M to be measured is arranged in the observation field VS or VF of the search system optical system or fine system optical system of the wafer alignment sensor 117. Immediately after the move is complete. That is, the wafer stage 110 vibrates with the movement of the wafer stage 110 and is left in a state where it has not yet been settled, and immediately, a positional deviation in the focus direction of the wafer W with respect to the focal plane of the optical system is detected. To do.

  At this time, the signal processing unit 280 sends a control signal to the focus camera 231 via the focus unit 239, and at the same time, the data from the Z interferometer 261 and the linear scale 262 also passes through the other sensor units 269. Instruct to capture in sync with capture. Then, the focus state detection result (focus shift amount) at this time is set to the distance S between the surface plate 131 and the column 132 and the distance d between the wafer stage 110 and the surface plate 131 measured by the Z interferometer 261 and the linear scale 262. Based on this, a correct value of the focus shift amount is obtained. Then, the wafer stage 110 is driven via the stage control system 114 and the driving device 111 so that the deviation amount becomes zero.

  The monitor 290 is, for example, a monitor for an operator or the like to observe images captured by the search cameras 211 and 212, the fine cameras 221 to 223, and the focus camera 231, and is transferred via the monitor video output line 271. Displayed image signal.

Next, the operation of the wafer alignment system 200 having such a configuration will be described with reference to FIG.
FIG. 7 is a flowchart showing the flow of the alignment process.
Alignment is started by loading the wafer W on which the previous process is completed in a pre-aligned state on the wafer stage 110 (step S10).
First, the stage control system 114 drives the wafer stage 110 via the driving device 111, so that the alignment mark (first search shot region SS1) is centered on the field of the observation observation field VS of the wafer alignment sensor 117. Are moved (step S12). The position of the wafer W is monitored with high accuracy by the laser interferometer 113 via the wafer stage 110, and the stage control system 114 positions the position of the wafer W with high accuracy based on the monitoring result.

  When the movement of the wafer W is completed, the wafer alignment sensor 117 immediately adjusts the focus of the wafer alignment sensor 117 regardless of whether or not the vibration of the wafer stage 110 is stabilized (step S13). That is, the focus state detection function of the wafer alignment sensor 117 detects the amount of deviation of the surface of the wafer W where the alignment mark is formed from the focal plane of the optical system of the wafer alignment sensor 117. At the same time, the Z interferometer 261 and the linear scale 262 detect the distance S (see FIG. 4) between the surface plate 131 and the column 132 and the distance d between the wafer stage 110 and the surface plate 131. When these distances are measured, the position of the wafer stage 110 is detected based on the distance S and the interval d, and the amount of deviation from the reference position is detected. Then, the deviation amount in the focus direction of the alignment mark forming surface of the wafer W is corrected by the deviation amount of the wafer stage 110, and the deviation amount in the true focus direction is detected. Then, the wafer stage 110 is driven in the Z direction via the main control system 115, the stage control system 114, and the driving device 111, and the alignment mark forming surface is adjusted to coincide with the in-focus surface of the wafer alignment sensor 117.

When the alignment AF is thus completed, the search shot area SS1 illuminated with an illumination beam from a halogen lamp or the like is imaged (step S14). That is, the search camera 211 of the search optical system captures an image of the observation visual field VS set as shown in FIG. 3, for example.
An imaging signal (image signal) obtained by imaging is converted into a digital signal by the search unit 219 and then output to the signal processing unit 280 via the data communication optical transmission path 270. Stored in the memory 281.
At this time, the index mark measurement camera 223 also measures the index mark using infrared light.

  The signal processing unit 280 that has captured the image of the first search shot area SS1 performs position measurement (search measurement) of the first search mark based on the captured image signal (step S16). That is, the coordinate value (positional information) based on the visual field of the search camera 211 of the first search mark is measured.

When the search position measurement of the first search mark is completed, it is determined whether or not there is a search mark to be measured next (step S18). Here, since the second search mark (mark attached to the search shot SS2) exists as a search mark to be measured next, the search position of the second search mark is measured in the same manner as described above (step S12). To S16).
That is, returning to the process of step S12, the alignment mark of the second search shot area SS2 is moved to the center of the field of view for the search observation field VS of the wafer alignment sensor 117 (step S12), and focus adjustment is performed (step S13). The search visual field is imaged by the search camera 211 of the optical system for search of the wafer alignment sensor 117 (step S14). At the time of the focus adjustment in step S13, as described above, the stage 110 is moved in the Z direction based on a value obtained by correcting the measurement result of the focus camera 231 based on the outputs of the Z interferometer 261 and the linear scale 262. This is done by driving. The captured image signal is AD converted in the search unit 219 to be converted into a digital signal, and transferred to the signal processing unit 280 via the data communication optical transmission path 270. Then, based on the imaging signal imaged by the search camera 211, the coordinate value (position information) of the search mark in the second search shot area SS2 is obtained (step S16).

  When the imaging of the first and second search marks is completed and the measurement of all the search marks to be measured is completed (step S18), the signal processing unit 280 includes the measured coordinate values of the search marks, and An arithmetic process is performed based on the corresponding design coordinate value, and the design coordinate value of the fine mark on the wafer stage movement coordinate system XY is corrected for each EGA shot (step S20).

If the coordinate value of the fine mark (coordinate value of the EGA shot) is corrected by such search alignment, then EGA as fine alignment is executed.
In the present embodiment, the EGA process is performed by measuring the positions of the alignment marks attached to the six EGA shots ES1 to ES6 (fine alignment measurement).
First, the wafer stage 110 (wafer W) is moved so that the fine alignment mark of the first EGA shot ES1 is arranged at the position of the observation field VF of the fine optical system of the wafer alignment sensor 117 (step S24). .

When the movement of the wafer W is completed, the wafer alignment sensor 117 performs focus adjustment by the same method as the search measurement (the method described above) (step S25), and an EGA shot illuminated with an illumination beam from a halogen lamp or the like. The area ES1 is imaged (step S26). That is, the X direction measurement fine camera 221 and the Y direction measurement fine camera 222 capture images of the observation visual fields VFX and VFY, respectively.
An imaging signal (image signal) obtained by imaging is converted into a digital signal by the fine unit 229, and then output to the signal processing unit 280 via the data communication optical transmission path 270, in the signal processing unit 280. Stored in the memory 281.
Then, the signal processing unit 280 measures the position of the fine mark based on the captured image signal (step S28).

  When the position measurement of the alignment mark (fine mark) in the first EGA shot area ES1 is completed, it is determined whether or not there is a fine mark to be measured next (step S30). Here, since the second fine mark (mark attached to the EGA shot ES2) exists as the fine mark to be measured next, the position measurement of the second fine mark is performed in the same manner as described above (steps S24 to S24). S28).

  That is, returning to the process of step S24, the alignment mark of the second EGA shot area ES2 is moved to the center of the visual field of fine observation field VF of the wafer alignment sensor 117 (step S24). The fine field of view (VFX and VFY) is imaged by the fine camera 221 for X direction measurement and the fine camera 222 for Y direction measurement of the fine optical system of the alignment sensor 117 (step S26). The captured image signal is AD converted in the fine unit 229 to be converted into a digital signal, and transferred to the signal processing unit 280 via the data communication optical transmission path 270. Then, the coordinate values (position information) of the fine marks in the second EGA shot area ES2 are obtained based on the imaging signals respectively captured by the X direction measuring fine camera 221 and the Y direction measuring fine camera 222 (step). S28).

Such processing is sequentially repeated while there are EGA shots to be position-measured, and when the position measurement of the marks M of all EGA shots (in this embodiment, six EGA shots ES1 to ES6) is completed, The EGA calculation is performed using the position measurement result.
That is, a statistical calculation process such as a least square method is performed based on the measurement value and design value of each alignment mark, and X shift, Y shift, X scale, Y as position information regarding the array characteristics of shot areas on the wafer W are performed. Error parameters such as scale, rotation, and orthogonality are calculated.
Based on these error parameters, design coordinate positions are corrected for all shot regions on the wafer W (step S32).

  In the exposure apparatus 100, such alignment processing is performed on sequentially loaded wafers W to acquire position information of each shot area. Thereafter, the wafers W are sequentially aligned based on the position information. Exposure is performed on each shot area of the wafer W.

As described above, in the exposure apparatus 100 of the present embodiment, when the alignment mark M is arranged in the observation field of view of the wafer alignment sensor 117 during search measurement and EGA measurement alignment measurement, the vibration of the wafer stage 110 is stabilized. Alignment AF is performed immediately before starting. Therefore, the processing time can be shortened by the amount of time that has conventionally been waited until the wafer stage 110 is settled, and alignment measurement can be performed efficiently in a short time with high throughput.
In the present embodiment, the above-described alignment AF is performed before the measurement in both the search measurement and the EGA (fine) measurement, but the present invention is not limited to this. For example, in search measurement that requires relatively less accuracy than EGA measurement (fine alignment measurement), the above-described alignment AF processing is not performed, and search measurement may be performed to improve throughput. .

  Further, since the focus state detection result in the wafer alignment sensor 117 is corrected based on the measurement results in the Z interferometer 261 and the linear scale 262, an appropriate focus state is detected even if the wafer stage 110 vibrates. As a result, the focus state can be adjusted appropriately.

  Further, according to the method of the present embodiment, not only the error of the focus state detection result due to the vibration of the wafer stage 110 but also the error of the focus state detection result due to other factors can be corrected. Therefore, the alignment AF can be appropriately performed as compared with the conventional case.

  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.

  For example, in the wafer alignment system 200 described above, a search unit 219 for the search system cameras 211 and 212, a focus unit 239 for the fine system cameras 221 to 223, and a focus unit 239 for the focus camera 231. In addition, an interface unit is provided for each CCD camera. However, the configuration of the input sensor and the interface unit is not limited to such a case, and may be arbitrarily changed.

  The search unit 219, the fine unit 229, the focus unit 239, and the like perform encoding processing (signal processing) such as compression on the digital signal to be transmitted to the signal processing unit 280 as necessary. However, the form and type of processing are not limited to signal compression, and arbitrary processing may be performed. For example, an arbitrary process such as filtering on an image signal, extraction of only a necessary signal, conversion based on a desired function may be performed.

Further, the wafer alignment system 200 is configured to include only one signal processing unit 280 as a signal processing unit that generates a signal waveform or performs EGA measurement or the like, but a plurality of signal processing units cooperate with each other. It may be configured to perform each processing as described above. In that case, it is preferable that the plurality of signal processing units are also connected via the data communication optical transmission line 270.
Further, in such a configuration including a plurality of signal processing units, a search unit 219, a fine unit 229, a focus unit 239, data transmitted from them, and data processing between the plurality of signal processing units are performed. The form, the distributed form of the function, the signal processing method, etc., that is, the architecture as the signal processing system may be arbitrarily configured.

  Also, the physical specifications and communication protocols of the optical network as the data communication optical transmission path 270 and the position data communication optical transmission path 272 described above may use any standard and any protocol.

The number of search measurement shots may be any number as long as it is two or more, and the number of EGA measurement shots may be any number as long as it is three or more. Further, the shape of the mark may be arbitrary.
In addition, the configuration of the exposure apparatus 100, the EGA measurement method (calculation model, calculation parameter, etc.) and the like are not limited to this embodiment, and any configuration and method may be used.

FIG. 1 is a view showing the schematic arrangement of an exposure apparatus according to an embodiment of the present invention. FIG. 2 is a view for explaining alignment measurement shots arranged on a wafer to be processed by the exposure apparatus shown in FIG. FIG. 3 is a view for explaining an example of an observation field of view and a mark to be observed of the wafer alignment sensor of the exposure apparatus shown in FIG. FIG. 4 is a view for explaining the relative positional relationship and installation method of the wafer stage and the wafer alignment sensor of the exposure apparatus shown in FIG. FIG. 5 is a view showing the configuration of the wafer alignment system of the exposure apparatus shown in FIG. FIG. 6 is a flowchart showing a wafer alignment method using the exposure apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Exposure apparatus 102 ... Light source 103 ... Reflective mirror 104 ... Wavelength selection filter 105 ... Optical integrator 106 ... Reticle blind 107 ... Reflector mirror 108 ... Lens system 109 ... Projection optical system 110 ... Wafer stage 111 ... Drive apparatus 112 ... Moving mirror 113 DESCRIPTION OF SYMBOLS Laser interferometer 114 ... Stage control system 115 ... Main control system 116 ... Reticle alignment sensor 117 ... Wafer alignment sensor 118 ... Reference mark member 119 ... Alignment control system 120 ... Reticle stage 121 ... Input part 131 ... Surface plate 132 ... Column 200 ... Wafer alignment system 211 ... Search camera 212 ... Observation camera 219 ... Search unit 221 ... Fine camera for X direction measurement 222 ... Fine camera for Y direction measurement 223 ... Turtle for index mark measurement La 229 ... Fine unit 231 ... Focus camera 239 ... Focus unit 240 ... Position monitor unit 261 ... Z interferometer 262 ... Linear scale 269 ... Other sensors 270 ... Optical transmission path for data communication 271 ... Video output line for monitor 272 ... optical transmission line for position data communication 273 ... focus signal accumulation control line 280 ... signal processing unit 290 ... monitor

Claims (14)

A focus state detection method for detecting a focus state of the object in a focal direction of the position detection optical system with respect to a focusing surface of the position detection optical system for detecting the position of the object placed on the stage,
By irradiating the object with detection light and detecting the reflected light of the detection light, the amount of deviation of the object from the in-focus plane is detected,
Simultaneously with the detection of the shift amount, the position information of the stage in the focal direction is detected,
The focus state detection method, wherein the focus state of the object is calculated by correcting the shift amount based on the position information.   The focus of the stage is set so that the position of the focal direction of the object coincides with a focal plane of the position detection optical system based on the focus state detected by the focus state detection method according to claim 1. A focus adjustment method comprising adjusting a position in a direction.   A position detection method, wherein the position detection optical system detects a position of a predetermined location on the object, the position of the focus direction of which is adjusted by the focus adjustment method according to claim 2.   The position detection method according to claim 3, wherein the position of the predetermined portion of the object is detected by the position detection optical system in a state where the stage on which the object is placed is stationary. A method for detecting a position in a two-dimensional plane of a desired pattern formed on a substrate as the object,
Moving the stage so that the pattern formed on the substrate falls within the detection visual field of the position detection optical system;
Immediately after the substrate is moved, according to the focus adjustment method according to claim 2, the pattern region on the substrate arranged in the detection visual field of the position detection optical system becomes an in-focus surface of the position detection optical system. Adjust the position of the stage in the focal direction to match
Detecting the position in a two-dimensional plane perpendicular to the focal direction of the pattern formed on the substrate placed on the stage, the position of the focal direction being adjusted, by the position detection optical system. A characteristic position detection method.   Detection of the amount of shift in the focal direction with respect to the focal plane of the position detection optical system of the pattern area of the substrate, and detection of position information in the focal direction of the stage are performed immediately after the movement of the stage. The position detection method according to claim 5, wherein the position detection is performed in a state where the vibration of the stage accompanying the movement has not converged. By the position detection method according to claim 5 or 6, the position of the pattern of the position measurement target formed on the substrate placed on the stage is detected,
Aligning the substrate based on the detected position;
An exposure method comprising transferring and exposing a predetermined pattern onto the aligned substrate. A focus state detection device that detects a focus state of the object in a focal direction of the position detection optical system with respect to a focusing surface of the position detection optical system that detects a position of the object placed on the stage;
A deviation amount detecting means for detecting a deviation amount of the object with respect to the in-focus plane by irradiating the object with detection light and detecting reflected light of the detection light;
Stage position detection means for detecting position information of the stage in the focal direction simultaneously with the detection of the shift amount;
A focus state calculation means for calculating the focus state of the object by correcting the shift amount based on the position information;
A focus state detection device comprising: A focus state detection device according to claim 8;
Based on the focus state detected by the focus state detection device, the position of the stage in the focus direction is adjusted so that the position of the focus direction of the object coincides with the focal plane of the position detection optical system. Stage position adjusting means to perform,
A focus adjusting apparatus comprising: A focus adjustment device according to claim 9;
The position detection optical system for detecting a position of a predetermined location on the object, the position of the focus direction of which is adjusted by the focus adjustment device;
A position detecting device comprising:   The position detection apparatus according to claim 10, wherein the position of the predetermined portion of the object is detected by the position detection optical system in a state where the stage on which the object is placed is stationary. A position detection device for detecting a position of a desired pattern formed on a substrate as the object,
Stage moving means for moving the stage so that the pattern formed on the substrate falls within the detection visual field of the position detection optical system;
Immediately after the substrate is moved, the focal point of the stage is set so that a pattern region on the substrate arranged in a detection field of view of the position detection optical system coincides with a focal plane of the position detection optical system. The focus adjustment device according to claim 9, which adjusts the position in the direction;
The position detecting optical system for detecting a position in a two-dimensional plane perpendicular to the focal direction of the pattern formed on the substrate placed on the stage, the position of the focal direction being adjusted;
A position detecting device comprising:   Detection of the amount of shift in the focal direction of the pattern area of the substrate with respect to the focal plane of the position detection optical system by the shift amount detection means, and position information of the focus direction of the stage by the stage position detection means The position detection apparatus according to claim 12, wherein the detection is performed immediately after the stage is moved by the stage moving means in a state where the vibration of the stage accompanying the movement is not converged. The position detection device according to claim 12 or 13, wherein the position of the pattern of the position measurement target formed on the substrate placed on the stage is detected to align the substrate.
An exposure apparatus comprising: exposure means for transferring and exposing a predetermined pattern on the aligned substrate.

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