JP2006030021A - Position detection apparatus and position detection method - Google Patents

Abstract

A reticle alignment system capable of appropriately arranging a reticle mark near the center of a fine camera based on a position detection result at a low magnification by a search camera.
A search measurement error caused by a magnification amount, a distortion amount, or a rotation amount of an optical element 221 or a monitor imaging element 222 of a search observation system 228 is detected in advance, stored as a correction map, and actual search measurement is performed. The result is corrected using this correction map. Thereby, in the fine measurement, the reticle alignment mark RM is appropriately arranged at the center of the visual field of the fine observation system 229, and the alignment of the reticle alignment mark and the wafer reference mark can be performed with high accuracy.
[Selection] Figure 2

Description

  The present invention relates to a position detection apparatus and a position detection method for detecting the position of a substrate or a mask, which are suitable for application to an exposure apparatus used in a lithography process when manufacturing an electronic device such as a semiconductor element.

  In the manufacture of electronic devices such as semiconductor devices, liquid crystal display devices, CCD imaging devices, plasma display devices, thin film magnetic heads and the like (hereinafter collectively referred to as electronic devices), an exposure apparatus is used to manufacture photomasks and reticles (hereinafter referred to as electronic devices). The image of the fine pattern formed on the reticle is generally projected and exposed onto a substrate (hereinafter referred to as a wafer) such as a semiconductor wafer or a glass plate coated with a photosensitive agent such as a photoresist. At that time, it is necessary to align the reticle and the wafer with high accuracy and to superimpose the reticle pattern on the pattern on the wafer with high accuracy. 2. Description of the Related Art In recent years, pattern refinement and high integration in electronic devices are rapidly progressing, and there is a demand for higher-precision alignment in exposure apparatuses than ever before.

  The position measurement of the wafer is performed by measuring the position of the alignment mark formed on the wafer. As an alignment system that measures the position of the alignment mark, the mark is irradiated with light with a wide wavelength bandwidth, the reflected light is imaged with a CCD camera, etc., and the image data of the resulting alignment mark is processed to measure the mark position An FIA (Field Image Alignment) type off-axis alignment sensor is known. According to this FIA-based alignment sensor, it is difficult to be affected by the thin film interference caused by the resist layer, and it is possible to detect the position of an aluminum mark or an asymmetric mark with high accuracy.

  Like the wafer position detection, the reticle position detection is also performed by detecting an alignment mark formed on the reticle. As an alignment system for measuring the position of the reticle alignment mark, an exposure system that uses exposure light or light having the same wavelength as the exposure light as a detection light beam is generally used. For example, exposure light is irradiated onto an alignment mark formed on the reticle. In addition, a VRA (Visual Reticle Alignment) type sensor (hereinafter also referred to as a reticle alignment sensor) that captures reflected light with a CCD camera or the like, processes the image data of the obtained alignment mark, and measures the mark position. ) Etc. are known.

In this type of reticle alignment sensor, a wafer reference mark (wafer fiducial mark) patterned on a reference plate fixed on a wafer stage and a reticle alignment mark patterned on the reticle are imaged. Images are taken in the same field of view through the optical system, and the relative position of the wafer reference mark and the reticle alignment mark, in other words, the amount of deviation is obtained based on the obtained signal, and based on this, reticle alignment (reticle alignment) , Baseline measurement.
At this time, since the imaging optical system usually has its own imaging characteristics such as distortion, there is a possibility that an image captured by the camera will be distorted by passing through the imaging optical system, and an error may occur in the obtained position. There is. Therefore, in order to cope with such a state and detect the position of the reticle alignment mark with high accuracy, the imaging characteristics of the imaging optical system are detected in advance and stored, and the information about the imaging characteristics is stored. An alignment system (position detection device) that corrects the position of a wafer reference mark or a reticle alignment mark based on this has also been proposed (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 8-167571

  When a reticle alignment mark (sometimes simply referred to as a reticle mark) is detected by a reticle alignment sensor, immediately after the reticle is placed on the reticle stage, it is caused by a reticle drawing error, reticle loader reproducibility error, etc. The alignment sensor center and the alignment mark center are greatly deviated. For this reason, when aligning the reticle, a low-magnification search sensor (search camera) that can measure a wide field of view is used to first roughly measure the position of the reticle alignment mark. The reticle stage is driven so that the alignment mark is arranged at the center of the visual field of the fine sensor (fine camera). In addition, focus measurement is performed using a high-magnification fine sensor, focusing is performed, and final alignment mark detection and position measurement are performed with the fine sensor.

  By the way, as described above, after performing position adjustment at a low magnification with a search camera with a wide field of view and adjusting the position with a high magnification fine camera with high accuracy, the rotation error of the search camera or Even if the error occurs in the search measurement result due to magnification error, distortion, or magnification error of the low magnification search sensor optical system, and the reticle stage is moved based on the search measurement result, the reticle mark remains in the field of view of the fine camera. There are cases where it is not located near the center. If the reticle mark is placed near the peripheral edge away from the center of the field of view of the fine camera in this way, it will be affected by the distortion of the optical members in the fine measurement system, and the alignment accuracy will be reduced or the alignment will be reduced. May take a long time. In addition, if the reticle mark shift becomes large, the wafer fiducial mark and the reticle alignment mark are overlapped, and the reticle alignment mark cannot be detected and an error (measurement error) may occur.

  The present invention has been made in view of such problems, and its purpose is to appropriately arrange a reticle mark near the center of a fine camera based on a low-magnification position detection result by a search camera, thereby An object of the present invention is to provide a position detection device and a position detection method capable of detecting the position of a reticle mark with high accuracy.

  In order to achieve the above object, a position detection apparatus according to the present invention includes a first optical system (221 etc.) and a first photoelectric conversion element (222), and detects the position of a desired detection target (RM). A first position detecting means (228), a second optical system (223, 224, 225, etc.) and a second photoelectric conversion element (226X, 226Y), and the position of the desired detection target (RM) A position detecting device (201) including a second position detecting means (229) for detecting the position with higher accuracy than the first position detecting means (228), the first position detecting means (228). The correction means (160) for correcting the error generated in the detection result of the first position detection means (228) due to the constituent elements of the above-mentioned based on the correction data stored in advance, and the correction corrected by the correction means Based on the detection results, Drive means (160, 124) for moving the desired detection object and positioning the desired detection object within the detection field of view of the second position detection means, and the second position detection means ( 229) detects the position of the desired detection target (RM) moved within the detection visual field by the driving means (160, 124) (see FIGS. 1 and 2) (Claim 1).

  Preferably, the correction data is obtained by dividing the detection visual field of the first position detection unit into a plurality of quadrants (R1 to R4) and sequentially moving the detection target into the respective quadrants by the driving unit. Detection results (P1 to P4) in which the position of a certain reference mark in the detection visual field is sequentially detected by the first detection means, and the movement amount of the reference mark when the reference mark is sequentially moved by the driving means. (V1 to v4) obtained by comparing the detection results (Q1 to Q4) by the third position detecting means for detecting (see FIG. 5) (Claim 2).

Preferably, the correction data includes at least one of a magnification amount or an aberration amount generated in the first optical system and the first photoelectric conversion element, and a rotation amount of the first photoelectric conversion element. (Claim 3).
Preferably, the correction means stores the correction data as a map-type correction value corresponding to each location in the detection visual field of the first position detection means.
Preferably, the correction means stores a plurality of correction data corresponding to environmental conditions around the position detection means (see FIG. 7) (Claim 5).

Preferably, the electronic apparatus further includes an environmental sensor that detects at least one of temperature and atmospheric pressure as an environmental condition, and the correction unit is configured to output correction data suitable for the detected environment based on a detection result of the environmental sensor. The correction data is selected and used.
Preferably, when the position of the detection target is shifted from a predetermined position in a detection visual field of the second position detection unit by a predetermined amount or more during position detection by the second position detection unit, A predetermined warning is issued or correction data is automatically updated (claim 7).

Also preferably, the predetermined position of the desired detection target that is positioned in the detection visual field of the second position detection means by the drive means by evaluating the history of the detection results so far by the second position detection means. And a correction means for updating the correction data based on the calculation result of the calculation means.
Preferably, the detection target is a mark formed on a mask. In order to control the position of the mask, the position of the mark is roughly measured by the first position detection unit, and the second position is detected. The position of the mark is finely measured by the position detecting means.

  In the position detection method according to the present invention, after the position of a desired detection target is detected using the first position detection unit including the first optical system and the first photoelectric conversion element (step S19), The position of the desired detection target is detected with higher accuracy than the first position detection means by using the second position detection means including the second optical system and the second photoelectric conversion element (step S25). A correction step (step) for correcting an error that occurs in a detection result of the first position detection unit due to a component of the first position detection unit based on correction data stored in advance. S21) and a positioning step (step S23) for moving the desired detection target based on the detection result corrected in the correction step and positioning it within the detection field of view of the second position detection means. Have Serial second position detection means detects been the location of the desired detection target moving within the detection field by the positioning step (step S25) (see FIG. 7) (claim 10).

  Another position detection device according to the present invention is a position detection device that includes a detection optical system and a photoelectric conversion element, and photoelectrically detects a desired detection target and detects the position of the detection target. Correction means for correcting an error generated in the detection result of the position detection means due to the component of the detection means based on correction data stored in advance, and temperature or atmospheric pressure as an environmental condition around the position detection device An environmental sensor for detecting at least one of the correction data, the correction data includes a plurality of correction data provided for each of the environmental conditions, and the correction means includes the correction data from the plurality of correction data. The correction is performed using correction data selected based on the output of the environmental sensor.

  In this column, the reference numerals of the corresponding components shown in the attached drawings are shown for each component, but this is only for easy understanding and does not relate to the present invention. It is not intended to indicate that the means is limited to the embodiments described below with reference to the accompanying drawings.

  According to the present invention, based on the position detection result at a low magnification by the search camera, the reticle mark is appropriately arranged near the center of the fine camera, and thereby the position detection can detect the position of the reticle mark with high accuracy. An apparatus and a position detection method can be provided.

An embodiment of the present invention will be described with reference to FIGS.
In the present embodiment, the present invention will be described by exemplifying a projection exposure apparatus for manufacturing an electronic device that exposes a device pattern on a reticle onto a wafer.
FIG. 1 is a diagram schematically showing the overall configuration of the projection exposure apparatus.
An exposure apparatus 100 shown in FIG. 1 has a circuit pattern formed on a reticle R while synchronously moving a reticle R as a mask and a wafer W as a substrate in a one-dimensional direction (Y direction in the example shown in FIG. 1). Is a step-and-scan type scanning exposure apparatus (scanning stepper) that transfers the image to a shot area defined on the wafer W.

First, the overall configuration of the exposure apparatus 100 will be described.
The exposure apparatus 100 includes an illumination system 110, a reticle stage unit 120, a reticle alignment system 200, a projection optical system 130, a wafer stage unit 140, a wafer alignment sensor 170, a main focus system 150, and a main controller 160.

The illumination system 110 includes, for example, a light source 111 made of an excimer laser, an illuminance uniformizing optical system 112 including a beam shaping lens and an optical integrator (fly eye lens), an illumination system aperture stop plate (revolver) 113, a revolver drive system 114, A relay optical system 116 and a bending mirror 117 are included. In addition to these components, the illumination system 110 further includes components (not shown) such as optical members such as condenser lenses and reticle blinds.
In such an illumination system 110, first, an illumination beam IL such as KrF excimer laser light or ArF excimer laser light is emitted from the light source 111, for example. The light emission of the laser pulse in the light source 111 is controlled by the main controller 160. Note that an ultra-high pressure mercury lamp may be used as the light source 111. In that case, bright lines in the ultraviolet region such as g-line and i-line are used as the illumination beam IL.

The illumination beam IL emitted from the light source 111 is uniformed by the illuminance uniformizing optical system 112, and speckle reduction or the like is performed.
An illumination system aperture stop plate 113 made of a disk-shaped member is disposed at the exit portion of the illuminance uniformizing optical system 112. The illumination system aperture stop plate 113 has, for example, a normal circular aperture aperture stop, a small circular aperture aperture stop to reduce the coherence factor σ value, and an annular shape for annular illumination. And a plurality of aperture stops such as a modified aperture stop in which a plurality of apertures for the modified light source method are eccentrically arranged. The illumination system aperture stop plate 113 is rotationally driven by a revolver drive system 114 such as a motor controlled by the main controller 160, so that any aperture stop is placed on the optical path of the illumination beam IL. Arranged selectively.

A relay optical system 116 is disposed behind the illumination system aperture stop plate 113 with a reticle blind (not shown) interposed therebetween. The installation surface of the reticle blind has a conjugate relationship with the reticle R, and an area illuminated by the illumination beam IL on the reticle R is defined by the reticle blind.
A folding mirror 117 that reflects the illumination beam IL that has passed through the relay optical system 116 toward the reticle R is disposed at the subsequent stage of the relay optical system 116, and further downstream of the folding mirror 117 (light of the reflected illumination beam IL). A condenser lens (not shown) is disposed on the rear stage of the road.
When the illumination beam IL that has passed through the illumination system aperture stop plate 113 passes through the relay optical system 116, the illumination area of the reticle R is defined by a movable reticle blind (not shown), and is reflected vertically downward by the bending mirror 117. The predetermined region of the reticle R placed on the reticle stage 121 is illuminated with uniform illuminance through the condenser lens that is not.

The reticle stage unit 120 includes a reticle stage 121, a laser interferometer 122, a moving mirror 123, and a motor 124.
The reticle stage 121 sucks and holds the mounted reticle R via a vacuum chuck, electrostatic chuck or the like (not shown). The reticle stage 121 can be finely moved in the direction of the optical axis AX of the projection optical system 130 by a motor 124 and can be moved two-dimensionally and finely rotated in a plane (horizontal plane, XY plane) perpendicular to the optical axis AX. The
On the reticle stage 121, there are provided movable mirrors (only the movable mirror 123 in the X-axis direction is shown in FIG. 1) having the X-axis direction and the Y-axis direction as reflection surface directions, respectively. The provided laser interferometer (only the X-axis direction laser interferometer 122 is shown in FIG. 1) detects the positions in the X-axis direction and the Y-axis direction with a resolution of about 0.01 μm, for example.

The reticle alignment system 200 includes alignment sensors 201 and 202 disposed above the reticle R, and detects, for example, a reticle mark RM as shown in FIG. 3A formed on the reticle R by these alignment sensors. The position information is output to main controller 160. In main controller 160, based on the input positional information of reticle mark RM, motor 124 is controlled to move reticle stage 121 so that reticle R is positioned. Specifically, the position of reticle stage 121 is controlled so that the center point of pattern area PA of reticle R coincides with optical axis AX of projection optical system PL.
In reticle R, reticle alignment mark RM is formed near the outer periphery of reticle R.
The reticle R is appropriately replaced by a reticle exchange device (not shown).

  The projection optical system 130 has a common optical axis AX in the Z-axis direction, and is composed of a plurality of lens elements arranged so as to have a telecentric optical arrangement on both sides. As the projection optical system 130, a projection magnification of 1/4 or 1/5 is used as an example. When the illumination area on the reticle R is illuminated by the illumination beam IL, the pattern formed on the pattern surface of the reticle R is reduced and projected onto the wafer W whose surface is coated with the resist R by the projection optical system 130. The reduced image of the pattern of the reticle R is transferred to one shot area on the wafer W.

  The wafer stage unit 140 places the wafer W in a desired state at a desired position so that the pattern of the reticle R is appropriately transferred to a desired area of the wafer W by exposure light irradiated through the projection optical system 130. Hold on. In the wafer stage unit 140, the wafer stage 142 is placed on a surface plate (stage surface plate) 141 disposed below the projection optical system 130. The wafer stage 142 is actually composed of an XY stage that can move two-dimensionally in a horizontal plane (XY plane), a Z stage that is mounted on the XY stage and can be moved in the optical axis direction (Z direction), and the like. However, in FIG. 1, these are simply shown as a wafer stage 142. The wafer stage 142 is driven in the XY two-dimensional direction along the upper surface of the surface plate 141 by the drive system 147, and is also driven in the optical axis AX direction within a minute range of, for example, about 100 μm. Note that the surface of the surface plate 141 is processed to be flat and is uniformly plated with a low reflectance material such as black chrome.

A wafer W is held on the wafer stage 142 by vacuum suction or electrostatic suction through a wafer holder 143.
Further, on the wafer stage 142, there are provided movable mirrors (only the movable mirror 144 in the X-axis direction is shown in FIG. 1) with the X-axis direction and the Y-axis direction as the reflecting surface directions. The position of the wafer stage 142 is detected with a resolution of about 1 nm in each of the X-axis direction and the Y-axis direction by a laser interferometer provided in the direction (only the X-axis direction laser interferometer 145 is shown in FIG. 1). The The position detection result of the wafer stage 142 by the laser interferometer 145 is output to the main controller 160, and the main controller 160 controls the drive system 147 based on the information. By such a closed loop control system, for example, the wafer stage 142 is stepped to the exposure position of the next shot when the transfer exposure (scan exposure) of the pattern of the reticle R on one shot area on the wafer W is completed. When exposure for all shot positions is completed, the wafer W is exchanged with another wafer W by a wafer exchange device (not shown). The wafer exchange device is arranged at a position off the wafer stage 142, and is configured to deliver the wafer W via a wafer transfer system such as a wafer loader.

  On the wafer stage 142, there is provided a reference plate 146 on which one or more wafer reference marks (wafer fiducial marks (WFM)) for later-described reticle alignment and baseline measurement are formed. The surface position of the reference plate 146 (Z-direction position / reference mark formation surface) is set to be the same as the surface position of the wafer W. In the present embodiment, a wafer reference mark WFM as shown in FIG. 3B is formed on the reference plate 146.

The main focus system 150 measures the position of the surface of the wafer W in the Z direction.
The main focus system 150 includes an irradiation optical system 151 that irradiates light on the surface of the wafer W or the reference plate 146 from an oblique direction, and a light incident optical system 152 that receives reflected light of the light and detects obliquely incident light type focus. It is a system. The irradiation optical system 151 tilts an image forming beam or a parallel beam for forming an image of a pinhole or a slit toward the image forming plane of the projection optical system 130 with respect to the optical axis AX perpendicular to the wafer W surface. Irradiate from the direction. The light receiving optical system 152 receives the reflected light beam on the surface of the wafer W or the reference plate 146 of the imaging light beam or the parallel light beam irradiated by the irradiation optical system 151, and sends the obtained detection signal to the main controller 160. Output. Based on this signal, main controller 160 controls the position of wafer W in the Z direction with respect to the best image plane of projection optical system 130 via drive system 147.

  The main control device 160 controls each part of the exposure apparatus 100 so that each constituent part cooperates and the exposure apparatus 100 as a whole performs a desired exposure process. Specifically, for example, alignment (alignment) of the reticle R and the wafer W, stepping of the wafer W, control and adjustment of the exposure timing, etc. are performed. Note that the main control device 160 is constituted by, for example, a microcomputer.

  The wafer alignment sensor 170 detects the position of the wafer reference mark (WFM) formed on the reference plate 146 provided on the wafer stage 142 or the wafer alignment mark on the wafer W, and the detection result is sent to the main controller 160. Output to. In this embodiment, the wafer alignment sensor 170 is provided with an index serving as a detection reference, and the position of the mark is detected using the index as a reference. For example, the result of the image processing method disclosed in Japanese Patent Laid-Open No. 4-65603 is disclosed. An image sensor is used. However, other types such as a laser scanning sensor known in Japanese Patent Laid-Open No. 10-141915 or a laser interference sensor may be used.

  The reticle alignment system 200 is a component related to the position detection apparatus and position detection method of the present invention, and performs reticle alignment (reticle alignment) for each lot head, for example. The reticle alignment system 200 includes two alignment sensors 201 and 202 of the VRA type. Since the configurations and functions of the two alignment sensors 201 and 202 are the same, the configuration, functions, and operations of the alignment sensor 201 are described below. Will be described in detail.

FIG. 2 is a diagram illustrating a configuration of the alignment sensor 201.
The alignment sensor 201 includes a base 205, an alignment light source 211, image sensors 226X and 226Y such as a CCD, a monitor image sensor 222, beam splitters 215, 216, and 225, optical elements 212, 213, 218 such as a condenser lens and an objective lens, 221 and 224, reflection mirrors 214 and 223, illumination field stop 213, stop 217, and internal focusing lens 219.
Further, as shown in FIG. 1, between the alignment sensor 201 and the reticle R, a retracted position where the exposure light incident on the projection optical system 130 cannot be shifted, and a measurement position for aligning the reticle R or the wafer W The epi-illumination mirror 203 (same for 204 with respect to the alignment sensor 202) is installed.

The alignment light source 211 is a light source that emits a detection beam for alignment. In the present embodiment, the alignment light source 211 is configured to guide and use exposure illumination light emitted from the light source 111 (see FIG. 1). That is, a part of the light beam of the illumination beam IL is branched by a mirror (not shown), guided into the alignment sensor 181 by an optical fiber, and emitted as a detection beam (illumination beam) from the end of the optical fiber as the alignment light source 211.
The detection beam emitted from the alignment light source 211 reaches the internal focusing lens 219 via the optical elements 212, 214, 218, the illumination field stop 213, the beam splitters 215, 216, and the stop 217.
The inner focus system lens 219 is a focus adjustment mechanism (AF lens) that is moved along the optical path of the detection beam by a driving unit (not shown). Position information of the internal focusing lens 219 is detected by a position detector (not shown) and output to the main controller 160. Based on this information, a detection beam emitted from the alignment sensor 201 by the main controller 160 is desired. The position of the in-focus lens 219 is controlled via the drive system so that the focus state becomes.

The detection beam whose focus is adjusted by the inner focus lens 219 is emitted from the alignment sensor 201, reflected by the incident mirror 203, and shown in FIG. 3A on the reticle R in the illumination field defined by the illumination field stop 213. Such a reticle alignment mark RM is illuminated, and a wafer reference mark WFM as shown in FIG. 3B on the reference plate 146 is illuminated via the reticle R and the projection optical system 130 (see FIG. 1).
The reflected beam from the reticle alignment mark RM and the wafer reference mark WFM is reflected by the epi-illumination mirror 203, reaches the beam splitter 216 via the inner focal lens 219, the optical element 218, and the aperture 217, and is branched by the beam splitter 216. Are incident on the rough measurement system 228 and the fine observation system 229, respectively.

The reflected beam branched by the beam splitter 216 and incident on the rough measurement system 228 is incident on the monitor imaging element (rough measurement camera) 222 via the optical element 221. The monitor imaging element 222 observes a wider field of view than the X direction sensor 226X and the Y direction sensor 226Y of the fine observation system 229, which will be described later. The imaging signal obtained in this manner is output to an observation monitor (not shown) and to the main controller 160 (FIG. 1).
The main controller 160 detects the amount of misalignment between the reticle alignment mark RM and the wafer reference mark WFM in each of the X direction and the Y direction based on the input imaging signal, and the present invention stored in the main controller 160. The positional deviation amount is corrected using the correction map according to the above, and the position of the reticle stage 121 is controlled based on the corrected positional deviation amount. That is, the position of the reticle stage 121 is controlled so that the reticle mark is arranged at the center of the visual field of the fine measurement system 229.

  The reflected beam branched by the beam splitter 216 and incident on the fine observation system 229 reaches the beam splitter 225 via the reflection mirror 223 and the optical element 224, and is further branched by the beam splitter 225, and is further divided into the X direction sensors 226X and Y Each is incident on the direction sensor 226Y. The X direction sensor 226X is an image pickup element that picks up an image in the image pickup area Px extended in the X direction shown in FIG. 4A in order to measure the position of the observed mark in the X direction. The Y direction sensor 226Y is This is an imaging device that measures an image in the imaging area Py extended in the Y direction shown in FIG. 4A in order to measure the position of the observed mark in the Y direction. For example, a signal waveform indicating the signal intensity of the pattern signal in the X-axis direction as shown in FIG. 4B is obtained from the X-direction sensor 226X. The imaging signals obtained by these X direction sensor 226X and Y direction sensor 226Y are output to main controller 160.

The base 205 is a surface plate on which a reticle alignment system is mounted. The base 205 is composed of a member formed of a nonmagnetic material or a member whose surface is coated with a nonmagnetic material.
The above is the description of the schematic configuration of the exposure apparatus 100.

Next, the reticle alignment system 200 according to the present invention in the exposure apparatus 100 having such a configuration, and the method of detecting the position of the reticle R in the reticle alignment system 200 will be described with reference to FIGS.
In the exposure apparatus 100, the position of the reticle R is detected by the alignment sensor 201 (and the alignment sensor 202) as described above, and alignment with the wafer W is performed. At this time, the alignment sensor 201 first creates and stores data for correcting measurement errors such as distortion in the search observation system 228 before actually aligning the reticle R and the wafer W.
First, the correction data creation process will be described with reference to FIGS.

In exposure apparatus 100, mark FM (reference mark, fiducial mark) formed on reference plate 146 of wafer stage 142 is in the first to fourth quadrants within the field of search observation system 228 of alignment sensor 201. In this state, the position of the reference mark FM under each state is measured. Based on the measurement result, correction data in the search observation system is obtained.
In FIG. 5, the position of the wafer stage 142 is controlled by the main controller 160 via the drive system 147, and the reference mark FM is displayed on the first to first image sensors 222 (imaging field of view 222) on the monitor observation system 228. It is a figure which shows the state arrange | positioned to each 4th quadrant. Here, it is assumed that the monitor imaging element 222 has a camera coordinate system (monitor coordinate system) having an origin O (0, 0).

  First, the wafer stage 142 is controlled in the XY two-dimensional plane so that the reference mark FM is positioned in the first quadrant R1 of the monitor image sensor (state in FIG. 5A). Under this state, the image pickup signal picked up by the monitor image pickup device is subjected to signal processing (first position detecting means) to obtain the position P1 (coordinate value) of the reference mark FM on the camera coordinate system. Further, the stage position under this state (coordinate value Q1 on the stage movement coordinate system) is also obtained by the laser interferometer 145 (third position detecting means).

  Next, the wafer stage 142 is controlled to move in the -X direction (while the movement amount in the Y direction is controlled to 0) with reference to the measurement value of the interferometer 145, so that the state of FIG. To the state shown in FIG. That is, the wafer stage 142 is driven to position the reference mark FM in the fourth quadrant R4 of the monitor image sensor (state shown in FIG. 5B). In this state, the coordinate position P2 of the reference mark FM on the camera coordinate system and the coordinate position Q2 of the stage on the stage movement coordinate system are obtained in the same manner as described with reference to FIG. .

  Next, from the state of FIG. 5B, the wafer stage 142 is controlled to move in the −Y direction (while controlling the amount of movement in the X direction to 0) with reference to the measurement value of the interferometer 145, The state shown in FIG. 5C (a state in which the reference mark FM is positioned in the third quadrant R3) is set, and the coordinate position P3 of the reference mark FM on the camera coordinate system and the stage movement coordinate system are set in the same manner as described above. The coordinate position Q3 of the upper stage is obtained.

  After that, from the state of FIG. 5C, the wafer stage 142 is controlled to move in the + X direction (while the movement amount in the Y direction is controlled to 0) with reference to the measurement value of the interferometer 145. 5 (D) (the reference mark FM is positioned in the second quadrant R2), and the coordinate position P4 of the reference mark FM on the camera coordinate system and the stage movement coordinate system are set in the same manner as described above. The coordinate position Q4 of the stage at is obtained.

The coordinate values P1 to P4 on the camera coordinate system and the stage coordinate values Q1 to Q4 on the stage movement coordinate system measured as described above are input to the main controller 160.
The main controller 160 uses the coordinate values P1 to P4 and the coordinate values Q1 to Q4 to obtain the scaling error information in the X direction and the scaling error information in the Y direction of the search observation system 228.
Specifically, | P1x−P2x | and | P3x−P4x | are obtained based on the X coordinate positions (Pnx) of the coordinate values P1 to P4, while the X coordinate positions (Qnx) of the coordinate values Q1 to Q4 are obtained. | Q1x−Q2x | and | Q3x−Q4x | are obtained, and their ratios (| P1x−P2x | / | Q1x−Q2x | and | P3x−P4x |, | Q3x−Q4x |) are obtained. Then, the scaling error information in the X direction of the search observation system is obtained by calculating the average of the values obtained at P1, P2, Q1, and Q2 and the values obtained at P3, P4, Q3, and Q4.

Note that the Y-direction scaling error information of the search observation system is also obtained by the same calculation method as the X-direction scaling error information calculation method.
With such a measurement / calculation method, distortion correction information (X-direction scaling correction information, Y-direction scaling correction information) can be obtained for the entire search observation system.

In addition, by applying the above-described measurement / calculation methods, optimal correction map information (distortion information) for each individual region (area) or each position (point) in the search observation system (in the search observation visual field) ) Can also be obtained.
For example, in FIG. 5A, distortion information (X-direction scaling, Y-direction) in the first quadrant R1 is obtained by performing the same measurement and calculation as described above while moving the reference mark FM in the region of the first quadrant R1. Direction scaling). By applying this measurement method also in other quadrants (R2 to R4), distortion correction information for each quadrant (distortion correction map information for each quadrant) can be obtained.

Further, by reducing (finely) the driving step amount (movement amount) of the reference mark FM that is performed when performing the above-described measurement and calculation methods, each visual field position within the search observation visual field (finely). Distortion correction information (correction map information) can be obtained.
Note that the driving step amount (movement amount) of the reference mark FM when obtaining the correction map information as described above is the required positioning accuracy and reticle conditions (material, reflectivity, phase shift, etc.) to be measured. It can be set automatically or arbitrarily by the user depending on whether or not it is a reticle.

Further, it is desirable that a plurality of correction map information (correction data) as described above is provided in accordance with the environmental conditions (temperature, humidity, atmospheric pressure, etc.) in which the exposure apparatus 100 is placed.
In the present embodiment, correction map information optimum for various environmental conditions is obtained in advance by performing the above-described measurement / calculation method while changing the environmental conditions (temperature, atmospheric pressure). FIG. 6 is an example of a correction map information table obtained by such a measurement / calculation method, and a plurality of correction map information to be used (15 sets in this case) are prepared in advance by combinations of temperature and atmospheric pressure. Is.
For example, the temperature in the exposure apparatus (specifically, the ambient temperature of the reticle alignment system 200) is in the range of a degree or more and less than b degree, and the atmospheric pressure at that time is in the range of A atmosphere or more and less than B atmosphere. If there is, the first correction map (No. 1) is used as the correction information. On the other hand, the temperature is in the range of a degree or more and less than b degree, and the atmospheric pressure is in the range of B atmosphere or more and less than C atmosphere. If there is, the second correction map (No. 2) is used.

A plurality of correction map information may be averaged or weighted averaged. For example, when the temperature is a degree and the atmospheric pressure is B atmospheric pressure in the example of FIG. 2 is not used, but map no. 1 is also used as a weighted average (the weight of map No. 1 is made lighter than the weight of map No. 2), and a new correction map information No. 1 is obtained. 1 + 2 may be calculated and used.
Hereinafter, “correction map information (correction data)” may be referred to as “correction map”.

Next, a reticle alignment method to which the reticle position detection method according to the present invention using such correction data is applied will be described with reference to FIG.
FIG. 7 is a flowchart for controlling reticle alignment when, for example, the lots loaded with the reticle R mounted on the reticle stage 121 are sequentially subjected to exposure processing.

When the processing for controlling the reticle alignment is started, first, the environment of the exposure apparatus 100 is detected by the environment sensor 300 that is disposed around the reticle alignment system in the exposure apparatus 100 and detects the environment (temperature and pressure) therein. Condition detection is performed (step S11). That is, the temperature is detected by a temperature sensor provided in the environment sensor 300, and the atmospheric pressure is detected by an atmospheric pressure sensor.
When the environmental condition is detected, a correction map (correction data) suitable for the detected environmental condition is selected from a plurality of correction maps stored in advance (step S13). As described above with reference to FIG. 6, the correction map is stored in association with the temperature and the atmospheric pressure. Accordingly, a correction map that matches the detected temperature and atmospheric pressure is selected from these.
When the correction map is selected, it is detected whether or not reticle alignment processing is performed (step S17). Reticle alignment by the reticle alignment system 200 is performed, for example, immediately after the reticle R is loaded on the reticle stage 121 or when a lot leading wafer is processed.

  When performing reticle alignment, first, search measurement using the search observation system 228 (first position detection means) is performed (step S19). That is, main controller 160 drives motor 124 based on design information or the like so that reticle alignment mark RM of reticle R is arranged at the center of the visual field of search observation system 228 of alignment sensor 201, and reticle stage 121 is moved. Move. Then, in this state, the reticle alignment mark RM is observed at a relatively low magnification with respect to the fine observation system 229 by the search observation system 228, and the image is captured by the monitor image sensor 222. The amount of deviation from the visual field center O (the position of the reticle alignment mark RM) is detected.

  When the amount of deviation of the reticle alignment mark RM in the visual field of the monitor image sensor 222 is detected, the detected amount of deviation is corrected based on the correction map (correction data) selected in step S13 (step S21). Then, based on the corrected deviation amount, main controller 160 drives motor 124 to move reticle stage 121 and adjust its position so that reticle alignment mark RM is at the center of the visual field (step S23). .

  When such search measurement is completed, fine measurement using the fine observation system 229 (second position detection means) is performed (step S25). That is, the reticle alignment mark RM is observed at a relatively high magnification with respect to the search observation system 228 by the fine observation system 229, the waveform data is detected by the X direction sensor 226X and the Y direction sensor 226Y, and the wafer at that position is detected. A deviation amount from the reference mark WFM is detected.

At this time, the reticle alignment mark RM should be arranged in the vicinity of the center of the visual field of the fine observation system 229 by performing the search alignment in consideration of the correction data as described above. Therefore, the amount of deviation detected in step S25 is compared with a predetermined threshold value THL, and it is detected whether or not the reticle alignment mark RM is appropriately arranged near the center of the visual field of the fine observation system 229 (step S27).
If this deviation amount is larger than the threshold value THL, it is considered that the search alignment is not properly performed, for example, the search measurement result is not properly corrected in step S21. To prompt the user to recalibrate (step S29).

  When such a warning is issued, for example, the history of measurement results obtained so far by the fine observation system 229 is evaluated, the tendency of the deviation of the reticle alignment mark RM is obtained, and the correction map is corrected as necessary. . The correction map correction processing may be performed by an operator based on history data stored in a storage unit provided in the main control device 160 of the exposure apparatus 100, for example. Alternatively, main controller 160 performs, for example, a calculation for determining a tendency of positional deviation of reticle alignment mark RM set in advance to automatically analyze the tendency of positional deviation, and further updates a preset correction map. The correction map may be automatically updated based on the analysis result of the misalignment tendency by a processing program or the like.

Then, based on the deviation amount obtained in step S25, main controller 160 drives reticle stage 121 via motor 124, and aligns reticle alignment mark RM and wafer reference mark WFM with high accuracy (step). S31).
Thereby, the reticle alignment is completed, and further, when the series of lot processes is completed and the exposure apparatus 100 is substantially stopped, this reticle alignment process in the main controller 160 is also completed (step S33). .

As described above, the exposure apparatus 100 according to the present embodiment detects in advance the amount of displacement of the measurement position of the search observation system 228 due to magnification error or distortion of the optical system or imaging system, or rotation of the imaging device (camera). It is stored as a correction map for correcting the measurement result of the measurement. The search measurement result by the search observation system 228 is corrected by a correction map and used for fine measurement. Therefore, high-precision search alignment that is not affected by such magnification error or distortion can be performed.
As a result, in fine measurement, the reticle alignment mark RM can be appropriately arranged near the center of the visual field of the fine observation system 229, and fine measurement can be appropriately performed near the visual field center of the fine observation system 229. That is, the reticle alignment mark RM and the wafer reference mark can be aligned with high accuracy.

Finally, a device manufacturing method using the exposure apparatus 100 according to the present embodiment in the lithography process will be described with reference to FIG.
FIG. 8 is a flowchart showing a manufacturing process of an electronic device such as a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, or a micromachine.
As shown in FIG. 8, in the manufacturing process of the electronic device, first, the function / performance design of the device such as the circuit design of the electronic device is performed, and the pattern design for realizing the function is performed (step S810). Then, a reticle on which the designed circuit pattern is formed is manufactured (step S820).
On the other hand, a wafer (silicon substrate) is manufactured using a material such as silicon (step S830).

Next, using the reticle manufactured in step S820 and the wafer manufactured in step S830, an actual circuit or the like is formed on the wafer by a lithography technique or the like (step S840).
Specifically, first, a thin film with an insulating film, an electrode wiring film, or a semiconductor film is formed on the wafer surface (step S841), and then the entire surface of the thin film is exposed using a resist coating apparatus (coater). An agent (resist) is applied (step S842).
Next, the resist-coated substrate is loaded onto the wafer holder, and the reticle manufactured in step S830 is loaded onto the reticle stage, and the pattern formed on the reticle is reduced and transferred onto the wafer (step S843). ). At this time, the exposure apparatus sequentially aligns each shot area of the wafer by the above-described alignment method according to the present invention, and sequentially transfers the reticle pattern to each shot area.

When the exposure is completed, the wafer is unloaded from the wafer holder and developed using a developing device (developer) (step S844). Thereby, a resist image of a reticle pattern is formed on the wafer surface.
Then, the wafer subjected to the development process is etched using an etching apparatus (step S845), and the resist remaining on the wafer surface is removed using, for example, a plasma ashing apparatus (step S846).
Thereby, patterns such as an insulating layer and electrode wiring are formed in each shot region of the wafer. Then, by repeating this process sequentially with the reticle changed, an actual circuit or the like is formed on the wafer.

Once a circuit or the like is formed on the wafer, the device is then assembled (step S850). Specifically, the wafer is diced and divided into individual chips, each chip is mounted on a lead frame or a package, bonding for connecting electrodes is performed, and packaging processing such as resin sealing is performed.
Then, inspections such as an operation confirmation test and a durability test of the manufactured device are performed (step S860), and the device is shipped as a completed device.

  In addition, this embodiment is 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 can be made.

For example, the overall configuration of the exposure apparatus is not limited to the configuration shown in FIG.
For example, it may be a system in which another computer is connected to an intranet and processing is distributed, a system constructed via another communication network, or a so-called server client type A system constructed as a system may also be used. The form of sharing of processing such as calculations for calculation and control in each apparatus of the exposure system, in other words, the distributed form of functions as a distributed processing system, or the connection form of these apparatuses as a network system is an arbitrary form As good as

The present invention is not limited to a step-and-scan type exposure apparatus, but to various types of exposure apparatuses including a step-and-repeat type or proximity type exposure apparatus (such as an X-ray exposure apparatus). Can be applied in exactly the same way.
The exposure illumination light (energy beam) used in the exposure apparatus is not limited to ultraviolet light, but may be charged particle beams such as X-rays (including EUV light), electron beams and ion beams. Further, it may be an exposure apparatus used for manufacturing a DNA chip, a mask, a reticle or the like.

FIG. 1 is a view showing the arrangement of an exposure apparatus according to an embodiment of the present invention. FIG. 2 is a view showing the arrangement of the alignment sensor of the exposure apparatus shown in FIG. FIG. 3 is a diagram showing the reticle alignment mark RM and the wafer reference mark. FIG. 4 is a diagram showing signal waveforms for detecting a state in which the reticle alignment mark RM and the wafer reference mark shown in FIG. FIG. 5 is a diagram for explaining a correction map creation method. FIG. 6 is a view showing the form of a correction map stored in the exposure apparatus shown in FIG. FIG. 7 is a flowchart showing the flow of reticle alignment. FIG. 8 is a flowchart for explaining the device manufacturing method.

Explanation of symbols

100: Exposure apparatus.
DESCRIPTION OF SYMBOLS 110 ... Illumination system 112 ... Illuminance equalization optical system 113 ... Illumination system aperture stop plate (revolver)
DESCRIPTION OF SYMBOLS 114 ... Revolver drive system 116 ... Relay optical system 117 ... Bending mirror 120 ... Reticle stage part 121 ... Reticle stage 122 ... Laser interferometer 123 ... Moving mirror 124 ... Motor 130 ... Projection optical system 140 ... Wafer stage part 141 ... Surface plate 142 ... Wafer stage 143 ... Wafer holder 144 ... Moving mirror 145 ... Laser interferometer 146 ... Reference plate 147 ... Drive system 150 ... Main focus system 151 ... Irradiation optical system 152 ... Light receiving optical system 160 ... Main controller 200 ... Reticle alignment system 201 , 202 ... Alignment sensor 203, 204 ... Epi-illumination mirror 205 ... Base 211 ... Alignment optical system 212, 213, 218, 221, 224 ... Optical element 213 ... Illumination diaphragm 214, 223 ... Reflection mirror 217 ... Diaphragm 219 ... In-focus Lens 222 ... monitor image sensor 226 ... imaging element 228 ... search observation system 229 ... Fine observation system 300 ... environment (temperature and pressure) sensor

Claims (18)

A first position detecting means for detecting a position of a desired detection target; a second optical system; and a second photoelectric conversion element. A position detection device including a second position detection means for detecting a position of a detection target with higher accuracy than the first position detection means,
Correction means for correcting an error that occurs in the detection result of the first position detection means due to the components of the first position detection means based on correction data stored in advance;
Drive means for moving the desired detection target based on the detection result corrected by the correction means and positioning the desired detection target within the detection field of view of the second position detection means. And
The position detection device, wherein the second position detection means detects the position of the desired detection object moved into the detection visual field by the driving means.   The correction data is obtained by dividing the detection field of the first position detection unit into a plurality of quadrants, and sequentially moving the reference mark within the detection field of the detection target moved into the quadrants by the driving unit. The detection result obtained by sequentially detecting the position at the first detection means and the detection result obtained by the third position detection means for detecting the movement amount of the reference mark when the reference mark is sequentially moved by the driving means. The position detection apparatus according to claim 1, wherein the position detection apparatus is data obtained by comparing   The correction data includes at least one of a magnification amount or an aberration amount generated in the first optical system and the first photoelectric conversion element, and a rotation amount of the first photoelectric conversion element. The position detection device according to claim 1 or 2.   The said correction | amendment means memorize | stores the said correction data as a map-type correction value corresponding to each location in the detection visual field of the said 1st position detection means, The any one of Claims 1-3 characterized by the above-mentioned. The position detection apparatus described in 1.   5. The position detection apparatus according to claim 1, wherein the correction unit stores a plurality of correction data according to environmental conditions around the position detection unit. An environmental sensor for detecting at least one of temperature and atmospheric pressure as the environmental condition;
The position according to claim 5, wherein the correction unit selects and uses correction data suitable for the detected environment from the plurality of correction data based on a detection result of the environment sensor. Detection device.   When detecting the position by the second position detecting means, a predetermined warning is issued if the position of the detection target is deviated by a predetermined amount or more from a predetermined position in the detection visual field of the second position detecting means. Or a correction data automatic update process. 7. The position detection apparatus according to claim 1, wherein the correction data is automatically updated. A history of detection results so far by the second position detection means is evaluated, and the desired detection object positioned in the detection visual field of the second position detection means by the drive means from the predetermined position is detected. It further has a calculation means for obtaining the tendency of deviation,
The position detection apparatus according to claim 7, wherein in the correction data automatic update process, the correction data is updated based on a calculation result by the calculation means.   The detection target is a mark formed on a mask, and in order to control the position of the mask, the position of the mark is roughly measured by the first position detection unit, and the second position detection unit The position detection apparatus according to claim 1, wherein the position of the mark is finely measured. After detecting the position of a desired detection target using the first position detection means including the first optical system and the first photoelectric conversion element, the second optical system and the second photoelectric conversion element are provided. A position detection method for detecting the position of the desired detection target with higher accuracy than the first position detection means using the second position detection means,
A correction step of correcting an error occurring in the detection result of the first position detection means due to the constituent elements of the first position detection means based on correction data stored in advance;
A positioning step of moving the desired detection target based on the detection result corrected in the correction step and positioning it within the detection field of view of the second position detection means,
The second position detection means detects the position of the desired detection target moved into the detection visual field by the positioning step.   The correction data is obtained by dividing the detection field of the first position detection unit into a plurality of quadrants, and sequentially moving the reference mark within the detection field of the detection target moved into the quadrants by the driving unit. The detection result obtained by sequentially detecting the position at the first detection means is compared with the measurement result of an interferometer that detects the amount of movement of the reference mark when the reference mark is sequentially moved by the driving means. The position detection method according to claim 10, wherein the position detection method is data obtained as described above.   11. The correction step uses correction data stored as correction values in a map format corresponding to each location in a detection field of view of the first position detection unit as the correction data. 11. The position detection method according to 11.   The position detection method according to any one of claims 10 to 12, wherein a plurality of the correction data are stored according to environmental conditions around the position detection means.   In the correction step, correction data suitable for the detected environment is selected from the plurality of correction data based on a detection result of an environmental sensor that detects at least one of temperature and atmospheric pressure as the environmental condition. The position detection method according to claim 13.   When detecting the position by the second position detecting means, a predetermined warning is issued if the position of the detection target is deviated by a predetermined amount or more from a predetermined position in the detection visual field of the second position detecting means. The position detection method according to claim 10, wherein correction data is automatically updated. In the automatic update process of the correction data,
A history of detection results obtained so far by the second position detection means is evaluated, and the desired detection target positioned in the detection field of view of the second position detection means during the positioning step from the predetermined position. Find the tendency of deviation,
The position detection method according to claim 15, wherein the correction data is updated based on the obtained tendency. A position detection device that includes a detection optical system and a photoelectric conversion element, photoelectrically detects a desired detection target, and detects the position of the detection target.
Correction means for correcting an error occurring in the detection result of the position detection means due to the component of the position detection means based on correction data stored in advance;
An environmental sensor that detects at least one of temperature and atmospheric pressure as an environmental condition around the position detection device;
The correction data includes a plurality of correction data provided for each environmental condition,
The position detecting device, wherein the correction means performs the correction using correction data selected from the plurality of correction data based on an output of the environmental sensor.   18. The position according to claim 17, wherein the correction data includes at least one of a magnification amount or an aberration amount generated in the detection optical system and the photoelectric conversion element, and a rotation amount of the photoelectric conversion element. Detection device.

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