JP4332891B2 - Position detection apparatus, position detection method, exposure method, and device manufacturing method - Google Patents

Description

  The present invention relates to a position detection apparatus, a position detection method, an exposure method, and a device manufacturing method. More specifically, the present invention relates to a position detection apparatus that detects position information of an object, and a position detection method using the position detection apparatus. Further, the present invention relates to an exposure method using the position detection method and a device manufacturing method using the exposure method.

  In a lithography process for manufacturing a semiconductor element, a liquid crystal display element, or the like, a wafer or glass on which a pattern formed on a mask or a reticle (hereinafter collectively referred to as “reticle”) is coated with a resist or the like via a projection optical system An exposure apparatus that transfers onto a substrate such as a plate (hereinafter collectively referred to as a “wafer”), such as a step-and-repeat reduction projection exposure apparatus (so-called stepper), or a step-and- A sequential movement type projection exposure apparatus (hereinafter abbreviated as “exposure apparatus”) such as a scanning scanning exposure apparatus (so-called scanning stepper) is mainly used.

  When manufacturing a semiconductor element or the like, different circuit patterns are stacked and formed on a wafer in several layers. However, if the overlay accuracy between the layers is poor, the circuit characteristics may be inconvenient. In such a case, the chip does not satisfy the desired characteristics, and in the worst case, the chip becomes a defective product, which decreases the yield. Therefore, in the exposure process, it is important to accurately superimpose and transfer the reticle on which the circuit pattern is formed and the pattern already formed on each shot area on the wafer.

  Therefore, in the exposure process, an alignment mark is previously attached to each of a plurality of shot areas on the wafer on which the circuit pattern is formed, and when the exposure process is performed again, the alignment mark on the wafer is The position of the alignment mark observed by the apparatus (the stage coordinate system of the wafer stage on which the wafer is placed (the coordinate system defining the movement of the wafer stage, usually the coordinate system defined by the measurement axis of the laser interferometer) ) Upper coordinate value) is detected based on the observation result. After that, based on the mark position information and the position information of the projection position of the known reticle pattern (which is measured in advance), the stage coordinate system and the array coordinate system defined by a plurality of shot areas on the wafer The so-called wafer alignment (fine alignment) is performed in which the positional relationship between each shot area and the projection position of the reticle pattern is determined in consideration of the deviation.

  Such an alignment mark (hereinafter referred to as a “fine alignment mark”) is observed at a high magnification from the viewpoint of enhancing detection accuracy. Therefore, the observation field of the observation apparatus when observing the fine alignment mark is inevitably narrow. Therefore, in order to reliably capture the mark in a narrow observation field, the deviation between the stage coordinate system and the array coordinate system is detected as follows prior to the observation of the alignment mark.

  First, by detecting an outer edge portion of the wafer including at least a notch (or orientation), a deviation of the wafer direction and center position on the wafer stage is roughly detected, and the wafer position is adjusted according to the deviation. This detection operation is generally called rough alignment.

  Further, at least two places on the wafer are provided with marks that can be observed at a low magnification by an observation device, so-called search alignment marks. After the rough alignment, each search alignment mark is observed by the observation device. Based on the observation result, the position of each search alignment mark is detected, and the rotation component and offset of the wafer are calculated based on the position of each search alignment mark. This detection operation is generally called search alignment.

  Thus, conventionally, in an exposure apparatus, a series of alignment processes such as rough alignment, search alignment, and fine alignment have been performed before exposure in order to realize highly accurate overlay exposure. Since it is used for mass production of semiconductor elements and the like, high throughput is required. In order to realize high throughput, it is desirable that the time required for alignment, which is a non-exposure time, be as short as possible.

  However, in the alignment process, a plurality of marks that are formed on the wafer together with the shot area and whose design positions are known and that are separated from each other by a predetermined distance or more are observed with some observation device, and the observation results are obtained. Based on the alignment.

  In this case, in order to observe each mark, the observation visual field of the observation device is sequentially moved to the region including the mark, and the mark is included in a state where the relative position between the imaging visual field and the object is kept constant. It was necessary to image the area. In other words, in order to capture a plurality of marks in the alignment process, it is necessary to move the observation visual field of the observation device to the position of each mark in order to make it stand still, and this operation shortens the time required for alignment. Had become a bottleneck.

  The present invention has been made under such circumstances, and a first object of the present invention is to provide a position detection device capable of detecting position information of an object in a short time.

  A second object of the present invention is to provide a position detection method capable of detecting position information of an object in a short time.

  A third object of the present invention is to provide an exposure method capable of realizing high throughput.

  A fourth object of the present invention is to provide a device manufacturing method capable of improving the productivity of microdevices.

The invention according to claim 1 is a position detection device that detects position information of an object, the storage-type imaging device; and while scanning the imaging field of the storage-type imaging device relative to the object in a predetermined direction. The reference that is compressed in the predetermined direction by continuously capturing an area including a reference line that defines the orientation of the object formed on the object at least once using the storage-type imaging device. and information on the detected the reference line; imaging mechanism and for acquiring an imaging result of a region including a line; based on the imaging result of the area including the reference line, the detector and for detecting information about the reference line And a calculation device that calculates information related to the orientation of the object based on the relative scanning speed .

According to this, at least an area including a reference line (for example, a scribe line between shot areas on a wafer) that defines the direction of an object while scanning the imaging field of view of the storage-type imaging device relative to the object in a predetermined direction. Take one image. By doing so, an imaging result of the area compressed in a predetermined direction (scanning direction) can be obtained. If the detection device detects information related to the reference line from the imaging result, the calculation device can calculate information related to the orientation of the object based on the detected information and the relative scanning speed. . Therefore, according to the present invention, information regarding the orientation of an object can be obtained by imaging during relative scanning in a predetermined direction without repeating the movement and stationary operation of the observation field of the observation apparatus to a plurality of locations as in the past. Can be detected in a short time.

In this case, as in the position detection device according to claim 2, the imaging mechanism uses a design-type position formed on the object by using the storage-type imaging device at the start or end of the relative scanning. An area including a mark whose information is known is further imaged, and the detection apparatus further detects position information of the mark based on an imaging result of the area including the mark, and the calculation apparatus detects the detected The position information of the object can be further calculated based on the position information of the mark, the information on the direction of the object, and the position information on the design of the detected mark .

According to a third aspect of the present invention, there is provided a position detection apparatus for detecting position information of an object, the storage type imaging device; and while scanning the imaging field of the storage type imaging device relative to the object in a predetermined direction. The reference that is compressed in the predetermined direction by continuously capturing an area including a reference line that defines the orientation of the object formed on the object at least once using the storage-type imaging device. An area including a mark obtained by acquiring an imaging result of an area including a line and having a known design position information formed on the object using the storage type imaging device at the start or end of the relative scanning An imaging mechanism for further imaging; detecting information on the reference line based on the imaging result of the area including the reference line, and the position of the mark based on the imaging result of the area including the mark A detection device for further detecting information; calculating information on the direction of the object based on the information on the detected reference line; information on the position of the detected mark and information on the direction of the object; and And a calculation device for further calculating the position information of the object based on the design position information of the detected mark. In the position detection device according to claim 2 or 3 , as in the position detection device according to claim 4 , the imaging mechanism is configured to change the direction of each coordinate axis of the two-dimensional coordinate system that defines the movement of the object, respectively. As the predetermined direction, an area including the reference line extending substantially parallel to each coordinate axis direction of the two reference lines orthogonal to each other while relatively scanning the imaging field of view of the storage-type imaging device with respect to the object Are detected at least once using the storage-type imaging device, the detection device detects information on the reference line based on the imaging result including the reference lines, and the calculation device Further, based on the detected information on each reference line, the orthogonality of each coordinate axis of the two-dimensional coordinate system is further calculated, and the positional displacement of the object is considered while considering the orthogonality. It can be to calculate the that information.

In the position detection device according to any one of claims 1 to 4 , as in the position detection device according to claim 5 , the storage type imaging device includes a plurality of photoelectric conversion elements two-dimensionally on the imaging surface. In the plurality of regions in the two-dimensional image obtained as the imaging result, the detection device obtains a cumulative value of luminance data for each pixel column in a direction corresponding to the predetermined direction. It is possible to create a data string of the cumulative value related to the orthogonal direction of the corresponding direction for each region, and detect information related to the reference line for the generated data string of the cumulative value of each region.

The position detecting device according to any one of the above claims 1-4, as the position detection apparatus according to claim 6, wherein the storage-type imaging device, arranged a plurality of photoelectric conversion elements two-dimensionally on an imaging surface The detection device extracts a plurality of pixel columns in a direction orthogonal to a direction corresponding to the predetermined direction from the two-dimensional image obtained as the imaging result, and the extracted luminance data of each pixel column The information on the reference line can be detected based on the data string.

The position detecting device according to any one of the above claims 1-4, as a position detecting device according to claim 7, wherein the imaging mechanism, at the time of the predetermined direction of relative scanning, continuous multiple times By performing the imaging, a plurality of imaging results of the area including the reference line compressed in the predetermined direction can be acquired.

In this case, as in the position detection device according to claim 8 , in the storage-type imaging device, the plurality of photoelectric conversion elements are arranged in a row in a direction corresponding to the orthogonal direction of the predetermined direction on the imaging surface. It can be an imaging device.

In the position detection apparatus according to claim 7 , as in the position detection apparatus according to claim 9 , the storage type imaging device is an imaging device in which a plurality of photoelectric conversion elements are two-dimensionally arranged on an imaging surface. And the detection device obtains a cumulative value of luminance data for each pixel column in a direction corresponding to the predetermined direction within a predetermined region in the two-dimensional image obtained as the imaging result, and is orthogonal to the corresponding direction. A data string of the cumulative value relating to the reference value is created, and information relating to the reference line is detected based on the created data string.

In the position detection device according to claim 7 , as in the position detection device according to claim 10 , the storage-type imaging device is an imaging device in which a plurality of photoelectric conversion elements are two-dimensionally arranged on an imaging surface. The detection apparatus extracts a pixel row in a direction orthogonal to a direction corresponding to the predetermined direction from the two-dimensional image obtained as the imaging result, and based on the data row of luminance data of the extracted pixel row, Information on the reference line may be detected.

The position detection device according to any one of claims 7 to 10 , wherein, as in the position detection device according to claim 11 , the reference line is a plurality of partitioned regions arranged in a matrix on the object. The imaging mechanism can perform each imaging at an interval such that the arrangement state of the partitioned areas corresponding to the imaging results is substantially the same.

The position detection device according to any one of claims 7 to 11 , wherein, as in the position detection device according to claim 12 , the imaging mechanism performs imaging three times or more during relative scanning in the predetermined direction. In this case, the detection device can detect information on the reference line by maximum likelihood estimation based on each imaging result.

  The position detection device according to any one of claims 1 to 12, wherein, as in the position detection device according to claim 13, the detection device relates to the reference line based on a folded correlation of a data string. Information can be detected.

  The position detection device according to any one of claims 1 to 12, wherein, as in the position detection device according to claim 14, the detection device uses the reference line based on the correlation between different data strings. The information about can be detected.

The invention according to claim 15 is a position detection device for detecting position information of an object, wherein the storage type imaging device is configured to scan the imaging field of the storage type imaging device relative to the object in a predetermined direction. The reference that is compressed in the predetermined direction by continuously capturing an area including a reference line that defines the orientation of the object formed on the object at least once using the storage-type imaging device. An imaging mechanism that acquires an imaging result of an area including a line; a detection device that detects information about the reference line based on an imaging result of an area including the reference line; and information about the detected reference line; A calculation device that calculates information related to the orientation of the object based on a design value of information related to the reference line .

The invention according to claim 18 is a position detection device for detecting position information of an object, comprising: a storage-type imaging device; while scanning the imaging field of view of the storage-type imaging device relative to the object in a predetermined direction. The reference line that is formed on the object and includes a reference line that defines the orientation of the object is continuously imaged at least once using the storage type imaging device and is compressed in the predetermined direction. When the relative scanning is started or ended, the storage type imaging device is used to obtain an area including a mark having a known design position information formed on the object. An imaging mechanism for further imaging and acquiring an imaging result of the area including the mark; and an area including the mark by detecting information on the direction of the reference line based on the imaging result of the area including the reference line Based on the position information and position information on the detected mark design orientation related information and the mark of the detected said reference line; based on the imaging result, the detection device and for further detecting the position information of the mark And a calculation device for calculating position information of the object.

According to this, a reference line (for example, a scribe line between shot areas on a wafer) that defines the direction of an object while causing the imaging mechanism to scan the imaging field of view of the storage type imaging device relative to the object in a predetermined direction. The area including the image is imaged, and the imaging result of the area including the mark is acquired before and after the relative scanning. In this way, the detection device detects information on the direction of the reference line from the compressed imaging result of the area including the reference line, and detects the position information of the mark based on the imaging result of the area including the mark. Further, in the calculation device, the position information of the object can be calculated based on the information regarding the direction of the detected reference line, the position information of the mark, and the design position information of the detected mark . Therefore, according to the present invention, as before, during the relative scanning in a predetermined direction and one stop operation before and after that, without repeatedly moving and stopping the observation field of the imaging device to a plurality of locations. It is possible to detect the position information of the object in a short time only by imaging.

The invention according to claim 19 is a position detection method for detecting position information of an object, and detects the position information of the object using the position detection device according to any one of claims 1 to 18. A position detection method including a process. In such a case, since the position information of the object is detected using the position detection device according to any one of claims 1 to 18 , the position information of the object can be detected in a short time.

The invention described in claim 20 is an exposure method for transferring a pattern to an object held by a moving body, and uses the position detection method according to claim 19 to position information on the object on the moving body. And a step of transferring the pattern to the object while controlling the position of the object held on the moving body based on the detected position information of the object. is there.

According to this, the position information of the object on the moving body is detected in a short time using the position detection method according to claim 19, and the position control of the object is performed based on the detection result Since transfer is performed, high throughput can be realized.

A twenty-first aspect of the present invention is a device manufacturing method including a lithography process, wherein the exposure is performed using the exposure method according to the twenty-first aspect. In such a case, since exposure is performed using the exposure method according to the twentieth aspect , high throughput can be realized, so that productivity of a highly integrated device can be improved.

    Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows a schematic configuration of an exposure apparatus 100 according to an embodiment to which the position detection method and the exposure method of the present invention are applied. The exposure apparatus 100 is a step-and-scan projection exposure apparatus. The exposure apparatus 100 includes an illumination system 10, a reticle stage RST on which a reticle R as a mask is mounted, a projection optical system PL, a wafer stage WST as a moving body on which a wafer W as an object is mounted, and an outer edge of the wafer W. A rough alignment detection system RAS for observing the shape, an alignment detection system AS, and a main controller 20 for overall control of the entire apparatus are provided.

  The illumination system 10 includes, for example, a light source, an illuminance uniformizing optical system including an optical integrator, a relay lens, a variable ND filter, a variable field stop (reticle blind or masking) as disclosed in Japanese Patent Laid-Open No. 6-349701. (Also referred to as a blade) and a dichroic mirror or the like (both not shown). As the optical integrator, a fly-eye lens, a rod integrator (an internal reflection type integrator), a diffractive optical element, or the like is used.

In the illumination system 10, a slit-shaped illumination area (a rectangular illumination area elongated in the X-axis direction) defined by the reticle blind on the reticle R on which a circuit pattern or the like is drawn is controlled by the main controller 20. Is illuminated with substantially uniform illuminance by the illumination light IL. Here, as the illumination light IL, far ultraviolet light such as KrF excimer laser light (wavelength 248 nm), ArF excimer laser light (wavelength 193 nm), vacuum ultraviolet light such as F ₂ laser light (wavelength 157 nm), or the like is used. . As the illumination light IL, it is also possible to use an ultraviolet bright line (g-line, i-line, etc.) from an ultra-high pressure mercury lamp.

  On reticle stage RST, reticle R is fixed, for example, by vacuum suction. Reticle stage RST is XY perpendicular to the optical axis of illumination system 10 (corresponding to optical axis AX of projection optical system PL described later) by a reticle stage drive unit (not shown) using a linear motor, a voice coil motor or the like as a drive source. It can be driven minutely in a plane and can be driven at a scanning speed specified in a predetermined scanning direction (here, the Y-axis direction which is the left-right direction in FIG. 1).

  The reticle stage RST is formed with a reflecting surface composed of a moving mirror or the like facing the X-axis direction and the Y-axis direction that reflects the laser light, and the position of the reticle stage RST within the stage moving surface is on the reflecting surface. For example, a reticle laser interferometer (hereinafter referred to as “reticle interferometer”) 16 that irradiates a laser always detects with a resolution of about 0.5 to 1 nm. Here, actually, a reticle X interferometer and a reticle Y interferometer are provided, but in FIG. 1, these are typically shown as a reticle interferometer 16. At least one of the reticle Y interferometer and the reticle X interferometer, for example, the reticle Y interferometer, is a two-axis interferometer having two measurement axes, and the reticle stage RST is based on the measurement value of the reticle Y interferometer. In addition to the Y position, the rotation amount (yawing amount) in the θz direction (rotation direction around the Z axis) can also be measured. Position information (including rotation information such as yawing amount) of reticle stage RST from reticle interferometer 16 is supplied to stage controller 19 and main controller 20 via this. The stage control device 19 drives and controls the reticle stage RST via a reticle stage drive unit (not shown) based on the position information of the reticle stage RST in response to an instruction from the main control device 20.

  Above the reticle R, a pair of reticle alignment detection systems 22 (however, in FIG. 1, the reticle alignment detection system 22 on the back side of the drawing is not shown) are arranged at a predetermined distance in the X-axis direction. Although not shown here, each reticle alignment detection system 22 includes an epi-illumination system for illuminating a detection target mark with illumination light having the same wavelength as the exposure light IL, and the detection target mark. And a detection system for capturing an image. The detection system includes an imaging optical system and an image sensor, and an imaging result (that is, a mark detection result by the reticle alignment detection system 22) by this detection system is supplied to the main controller 20. In this case, a deflection mirror (not shown) for guiding the detection light from the reticle R to the reticle alignment detection system 22 is movably arranged, and when an exposure sequence is started, based on a command from the main controller 20. The deflecting mirror is retracted out of the optical path of the exposure light IL integrally with the reticle alignment detection system 22 by a driving device (not shown).

  The projection optical system PL is disposed below the reticle stage RST in FIG. 1, and the direction of the optical axis AX is the Z-axis direction. As the projection optical system PL, a birefringent optical system having a predetermined reduction magnification (for example, 1/5 or 1/4) is used. Therefore, when the illumination area of the reticle R is illuminated by the illumination light IL from the illumination system 10, a reduced image (partial inverted image) of the illumination area portion of the circuit pattern of the reticle R is passed through the projection optical system PL through the wafer W. It is projected onto a projection area in the field of view of the projection optical system conjugate with the illumination area above, and transferred to the resist layer on the surface of the wafer W.

  Wafer stage WST is arranged on a base (not shown) below projection optical system PL in FIG. Wafer holder 25 is placed on wafer stage WST. A wafer W is fixed on the wafer holder 25 by, for example, vacuum suction.

  Wafer stage WST is rotated by X, Y, Z, θz (rotation direction around Z axis), θx (rotation direction around X axis), and θy (rotation direction around Y axis) by wafer stage drive unit 24 in FIG. ) In a single stage that can be driven in the direction of five degrees of freedom. For the remaining θz direction, wafer stage WST (specifically, wafer holder 25) may be configured to be rotatable, and yawing error of wafer stage WST is corrected by rotation on reticle stage RST side. It is also good.

  Wafer stage WST is formed with a reflecting surface made of a moving mirror or the like facing in the X-axis direction and Y-axis direction for reflecting laser light, and the position of wafer stage WST irradiates the reflecting surface with laser. For example, a wafer laser interferometer (hereinafter referred to as “wafer interferometer”) 18 disposed outside is constantly detected with a resolution of about 0.5 to 1 nm. In practice, an interferometer having a length measuring axis in the X-axis direction and an interferometer having a length measuring axis in the Y-axis direction are provided, but these are typically shown as a wafer interferometer 18 in FIG. Has been. These interferometers are composed of multi-axis interferometers having a plurality of measurement axes, and in addition to the X and Y positions of wafer stage WST, rotation (yawing (θz rotation that is rotation around the Z axis)), pitching (X axis) Rotation around (θx rotation) and rolling (θy rotation around Y axis)) can also be measured.

  A reference mark plate FM is fixed in the vicinity of wafer W on wafer stage WST. The surface of the reference mark plate FM is set to substantially the same height as the surface of the wafer W, and at least a pair of reticle alignment reference marks, a reference mark for baseline measurement of the alignment detection system AS, and the like are provided on this surface. Is formed.

  The rough alignment detection system RAS is held by a holding member (not shown) at a position separated from the projection optical system PL above the base (not shown). The rough alignment detection system RAS includes three rough alignment sensors 40a, 40b, and 40c that detect the positions of three outer edge portions of the wafer W held by the wafer holder 25 (in FIG. 1, the rough alignment sensor 40c is shown). , On the back side of the rough alignment sensor 40b, the illustration thereof is omitted). These three rough alignment sensors 40a, 40b, and 40c are respectively arranged at positions with a central angle of 120 degrees on the circumference of a predetermined radius (substantially the same as the radius of the wafer W), and one of them, here, The rough alignment sensor 40a is disposed at a position where the notch N (V-shaped notch) of the wafer W held by the wafer holder 25 can be detected. As these rough alignment sensors, an image processing type sensor composed of an image sensor and an image processing circuit is used. The rough alignment detection system supplies the main controller 20 with the detection result of the outer edge position of the wafer by the rough alignment sensors 40 a to 40 c according to an instruction from the main controller 20.

  The alignment detection system AS is an off-axis alignment sensor disposed on the side surface of the projection optical system PL. As this alignment detection system AS, for example, a broadband detection light beam that does not sensitize a resist on a wafer is irradiated onto a target mark, and an image of the target mark formed on a light receiving surface by reflected light from the target mark is not shown. The image of the index is captured using a storage solid-state imaging device composed of a photoelectric conversion element (for example, a photodiode) and a charge-coupled device element (for example, a CCD), and outputs an image signal of the FIA ( Field Image Alignment) type sensors are used. That is, in this alignment detection system AS, an X-line sensor (one-dimensional CCD) in which a plurality of photoelectric conversion elements are arranged in a row in a direction corresponding to the X-axis direction and a plurality of photoelectric conversion elements are provided on the imaging surface. Y line sensors (one-dimensional CCDs) arranged in a line in a direction corresponding to the Y-axis direction are provided, and imaging is performed by both line sensors.

  In both the line sensors, in response to an instruction from the main controller 20, signal charges accumulated according to the amount of light received in 1/60 s in each photoelectric conversion element are converted into charge transfer circuits connected to the photoelectric conversion elements. The output circuit samples the electrical signal corresponding to the transferred signal charge amount, and outputs the sampled signal to the main controller 20 as an imaging signal of each line sensor. That is, main controller 20 acquires a signal imaged by the X-line sensor as an imaging signal corresponding to one-dimensional imaging data along the X-axis direction, and uses the signal imaged by the Y-line sensor as the Y-axis direction. It can be acquired as an imaging signal corresponding to the one-dimensional imaging data along.

  The target mark is irradiated with coherent detection light, and scattered light or diffracted light generated from the target mark is detected, or two diffracted lights (for example, of the same order) generated from the target mark are interfered and detected. Of course, it is possible to use alignment sensors in appropriate combinations.

  In FIG. 1, the control system is mainly configured by a main control device 20 and a stage control device 19 subordinate thereto. The main control device 20 includes a so-called microcomputer (or workstation) including a CPU (central processing unit), a main memory, and the like, and controls the entire device.

  The main controller 20 includes, for example, a storage device including a hard disk, an input device including a pointing device such as a keyboard and a mouse, and a display device such as a CRT display (or a liquid crystal display) (all not shown), A drive device 46 for an information recording medium such as a CD (Compact Disc), a DVD (Digital Versatile Disc), an MO (Magneto-Optical Disc), or an FD (Flexible Disc) is connected externally. An information recording medium (hereinafter referred to as a CD) set in the drive device 46 has a program corresponding to a processing algorithm at the time of wafer alignment and exposure operations shown in the flowchart described later (hereinafter, “specific” for convenience). Other programs, and databases attached to these programs are recorded.

  The main controller 20 executes processing according to the above-described specific program so that, for example, the exposure operation is accurately performed, and controls, for example, synchronous scanning of the reticle R and the wafer W, step movement (stepping) of the wafer W, and the like. To do.

Specifically, the main controller 20 synchronizes with the reticle R being scanned in the + Y direction (or −Y direction) at the speed V _R = V via the reticle stage RST, for example, during scanning exposure. Through wafer stage WST, wafer W has a velocity V _W = β · V (β is the projection magnification from reticle R to wafer W) in the −Y direction (or + Y direction) with respect to the projection region conjugate with the illumination region. Based on the measurement values of the reticle interferometer 16 and the wafer interferometer 18 obtained through the stage control device 19 so as to be scanned, the reticle stage drive unit and wafer stage drive unit (not shown) are passed through the stage control device 19. The position and speed of reticle stage RST and wafer stage WST are controlled via 24 respectively. Further, at the time of stepping, main controller 20 controls the position of wafer stage WST via stage controller 19 and wafer stage drive unit 24 based on the measurement value of wafer interferometer 18.

  Further, the exposure apparatus 100 of the present embodiment supplies an image forming light beam for forming a plurality of slit images toward the best image forming surface of the projection optical system PL from an oblique direction with respect to the optical axis AX direction (not shown). And an oblique incidence type multi-point focus detection system comprising a light receiving system (not shown) that receives each reflected light beam of the imaging light beam on the surface of the wafer W through a slit. As this multipoint focus detection system, one having the same configuration as that disclosed in, for example, Japanese Patent Laid-Open No. 6-283403 is used, and the output of this multipoint focus detection system is supplied to the main controller 20. Yes. Main controller 20 drives wafer stage WST in the Z direction and the tilt direction via stage controller 19 and wafer stage drive unit 24 based on the wafer position information from the multipoint focus detection system.

  Next, with respect to the operation when performing exposure processing on the second layer (second layer) and subsequent layers on the wafer W by the exposure apparatus 100 of the present embodiment configured as described above, on the wafer W. 2A and 2B showing the arrangement of the shot area and the like and the flowcharts of FIGS. 3 to 5 showing the processing algorithm of the CPU in the main controller 20 executed according to the specific program, This will be described with reference to other drawings as appropriate.

  As a premise, the specific program and other programs in the CD-ROM set in the drive device 46 are assumed to be installed in the storage device inside the main storage device 20, and the reticle alignment and baseline of those programs are also included. It is assumed that a program such as a measurement process is loaded from the storage device into the main memory by the CPU inside the main controller 20.

  As shown in FIG. 2A, a plurality of shot regions S (i, j) (i =) are formed on the wafer W, which is the exposure target of the second and subsequent layers, as shown in FIG. 1 to m, j = 1 to n) are arranged in a matrix with a certain distance from adjacent shot regions. The shot coordinate area αβ is defined by the shot area.

Between adjacent shot regions, a scribe line Lα _i (i = 1 to _m −1) as a reference line extending in the α-axis direction and a scribe line Lβ _j (j = 1) as a reference line extending in the β-axis direction. To n-1). The shot region S (p, q) (p = 2 to m−2, q = 2 to n−2) is surrounded by scribe lines Lα _p−1 , Lα _p , Lβ _q−1 , Lβ _q Can be considered. In FIG. 2A, only the shot areas S (1,1), S (1, n), S (m, 1), and S (m, n) at the four corners are denoted by reference numerals. The code | symbol is abbreviate | omitted about shot area | region S (i, j). In addition, since the surface state is more uniform on the scribe lines Lα _i and Lβ _j than on the shot area, when the scribe line and the shot area are imaged by the FIA sensor, the imaging result of the scribe line The luminance is higher than the imaging result of the shot area.

Further, as shown in FIG. 2B, the wafer alignment X mark (on the scribe line Lα _i having a predetermined width between adjacent shot regions, for example, about 100 μm width, together with this shot region S (i, j). wafer X mark) MX (i, j) is formed, on the scribe line L? _j, wafer alignment Y marks (wafer Y mark) MY (i, j) are respectively formed. Among these, the X position of the wafer X mark MX (i, j) coincides in design with the X coordinate of the shot area S (i, j) (center C (i, j) thereof), and the wafer Y mark MY (i , J) is designed to coincide with the Y coordinate of the shot area S (i, j) (center C (i, j)). That is, in design, the center C (i, j) of the shot region S (i, j) (by the X position of the wafer X mark MX (i, j) and the Y position of the wafer Y mark MY (i, j). )) Position coordinates are obtained.

  In this case, as the wafer X mark MX (i, j), for example, a line and space mark whose periodic direction is the X-axis direction is used, and for the wafer Y mark MY (i, j), for example, the Y-axis direction is periodic. Line and space marks are used as directions.

  Information relating to the shot area S (i, j) on the wafer W as described above (that is, positional information of the wafer X mark MX (i, j) and wafer Y mark MY (i, j)), for example, array coordinates It is assumed that the design position in the system is stored in the storage device.

  A processing algorithm of the CPU in the main controller 20 will be described.

  As shown in FIG. 3, first, in step 301, reticle R is loaded onto reticle stage RST by a reticle loader (not shown). When this reticle loading is completed, in step 303 → step 305 → step 307, main controller 20 (more precisely, CPU) performs reticle alignment, baseline measurement, and wafer load, reticle alignment, baseline measurement as described above. , And in accordance with the wafer load processing program, the following is executed.

  That is, in step 303, main controller 20 causes reference mark plate FM on wafer stage WST to be a predetermined position directly below projection optical system PL via wafer stage drive unit 24 (hereinafter referred to as “reference position” for convenience). And the relative position between the pair of first reference marks on the reference mark plate FM and the pair of reticle alignment marks on the reticle R corresponding to the first reference mark is set to the above-described pair of reticle alignment detection systems 22. Use to detect. Then, main controller 20 stores the detection result of reticle alignment detection system 22 and the measurement values of interferometers 16 and 18 obtained through detection by stage controller 19 in the main memory. Next, main controller 20 moves wafer stage WST and reticle stage RST in the opposite directions along the Y-axis direction by a predetermined distance, respectively, to generate another pair of first reference marks on reference mark plate FM. And a pair of reticle alignment marks on the reticle R corresponding to the first reference mark are detected using the pair of reticle alignment detection systems 22 described above. Then, main controller 20 stores the detection result of reticle alignment detection system 22 and the measurement values of interferometers 16 and 18 obtained through detection by stage controller 19 in the main memory. Next, in the same manner as described above, the relative positional relationship between another pair of first reference marks on the reference mark plate FM and the reticle alignment mark corresponding to the first reference mark may be further measured.

  Then, main controller 20 obtains information on the relative positional relationship between the at least two pairs of first reference marks obtained in this way and the corresponding reticle alignment marks, and the measurements of interferometers 16 and 18 during the respective measurements. The relative position relationship between the reticle stage coordinate system defined by the measurement axis of the interferometer 16 and the wafer stage coordinate system defined by the measurement axis of the interferometer 18 is obtained using the value. Thereby, reticle alignment is completed.

  Next, at step 305, main controller 20 performs baseline measurement. Specifically, wafer stage WST is returned to the above-described reference position, moved from the reference position by a predetermined amount, for example, the design value of the baseline, in the XY plane, and then moved onto reference mark plate FM using alignment detection system AS. The second reference mark is detected (the measured value of the wafer interferometer 18 is stored in the main memory via the stage controller 19). Main controller 20 obtains information on the relative positional relationship between the detection center of alignment detection system AS and the second reference mark obtained at this time, and a pair of first reference values measured when wafer stage WST is first positioned at the reference position. Information on the relative positional relationship between the mark and the pair of reticle alignment marks corresponding to the first reference mark, the measurement value of the wafer interferometer 18 at each measurement, the known first reference mark and second reference Based on the positional relationship with the mark, the base line of the alignment detection system AS, that is, the distance (positional relationship) between the projection center of the reticle pattern and the detection center (index center) of the alignment detection system AS is calculated.

  Next, at step 307, main controller 20 instructs the control system of the wafer loader (not shown) to load wafer W. Thereby, wafer W is loaded onto wafer holder 25 on wafer stage WST by the wafer loader.

  When such a series of preparatory work is completed, main controller 20 unloads the above-described reticle alignment and baseline measurement processing programs from the main memory, and also executes a specific program for executing the alignment operation and the exposure operation. Is loaded into main memory. Thereafter, according to the specific program, the position detection method of the present embodiment, that is, rough alignment, search alignment, EGA wafer alignment, and exposure to each shot area on the wafer W are performed.

  First, in step 309, rough alignment is performed on the loaded wafer W. In this rough alignment operation, first, main controller 20 moves wafer stage WST via stage controller 19 and wafer stage drive unit 24, and notch N of wafer W is positioned directly below rough alignment sensor 40a and wafer W. The position of the wafer W is roughly aligned so that the outer edge of the wafer is directly below the rough alignment sensors 40b and 40c. In this state, the rough alignment sensor 40a detects the position of the notch N of the wafer W, and the rough alignment sensors 40b and 40c detect the outer edge position of the wafer W. These detection results are supplied to the main controller 20. Based on the detection results supplied from the rough alignment sensors 40a, 40b, and 40c, the main controller 20 matches the array coordinate system (α, β) on the wafer W within the approximate alignment coordinate system (α ', Β') is derived. Here, the main controller 20 may rotate the wafer holder 25 so that the X axis direction and the Y axis direction coincide with the α ′ axis direction and the β ′ axis direction, respectively. At this time, the stage coordinate system coincides with the approximate array coordinate system. In the following description, it is assumed that the stage coordinate system and the approximate array coordinate system coincide with each other by this rough alignment.

  Next, in subroutine 311, search alignment is performed. FIG. 4 shows a flowchart showing the processing of the subroutine 311. As shown in FIG. 4, in step 401, a position detection mark (search mark) to be detected is determined. Specifically, main controller 20 performs wafer X mark MX (i, j) or wafer Y mark MY (i, j) attached to each shot area S (i, j) shown in FIG. ) To select a search alignment mark. For example, any one of the aforementioned wafer Y marks MY (i, j) is determined as a search alignment mark, and the design position coordinates of the mark are read from the storage device.

Here, in order to simplify the description, the search alignment marks are the wafer X mark MX (i, j) and the wafer Y mark MY (i, j). Alternatively, another mark disposed on the scribe line Lβ _j may be used. Here, in consideration of scanning the imaging field of the alignment detection system AS on the scribe line Lβ _{j in} a process described later, a scanning section of the scribe line Lβ _j is sufficiently ensured. It is desirable to determine the wafer Y mark MY (i, j).

  In step 403, wafer stage WST is moved so that wafer Y mark MY (i, j) determined as the search mark falls within the imaging field of alignment detection system AS. In step 405, the alignment detection system AS is instructed to image the area including the search alignment mark, and the imaging result is acquired, and the position of wafer stage WST sent from wafer interferometer 18 is acquired. Then, the acquired imaging result (that is, imaging data by both line sensors in the X-axis direction and the Y-axis direction) and position information of wafer stage WST are stored in the storage device.

  Furthermore, in step 407, imaging conditions by the alignment detection system AS are set. Examples of such imaging conditions include the number of times of imaging and the imaging interval during one relative scan. Here, the number of times of imaging is Kc, the imaging interval is Ic, and Kc and Ic are set. At the same time, the value of the counter K used in the interrupt processing to be described later is initialized to 0, and the value of the counter I is initialized to Ic (here, 2 is set as the number of imaging times Kc and 3 is set as the imaging interval Ic). . As will be described later, when the imaging interval Ic is set to 3, the imaging interval in the alignment detection system AS is 1/60 × 3 = 1/20 s.

Next, in step 409, to initiate the relative scanning on the scribe line L? _J of the imaging field of the alignment detection system AS. Specifically, wafer stage WST is moved in the −Y direction at a predetermined moving speed (for example, V ′). As a result, the imaging field of view of the alignment detection system AS moves on the wafer W in the + Y direction at the movement speed V ′. Even in this case, since the wafer W is placed so that the scribe line Lβ _j is substantially along the Y-axis direction, the imaging field of view of the alignment detection system AS does not deviate from the scribe line Lβ _j . Note that the imaging magnification of the alignment detection system AS needs to be set such that the scribe line Lβ _j is sufficiently included in the imaging field of view.

  FIG. 6 shows how the imaging field of view of the alignment detection system AS moves in the + Y direction on the wafer W by the relative scanning. As described above, since the time required for one imaging of the alignment detection system AS is 1/60 s, when the imaging field of view of the alignment detection system AS moves in the + Y direction at the moving speed V ′, the alignment detection system AS The X-line sensor imaging range (indicated by a dotted line in FIG. 6) is expanded in the Y-axis direction, and its length is L (= 1/60 × V ′). By continuous imaging during the relative scanning, imaging data compressed in the Y-axis direction can be obtained by the X-line sensor of the alignment detection system AS. That is, if the alignment detection system AS continuously captures images at 1/60 s intervals, the captured image data of the section A in FIG. 6 is compressed and the image capturing range of the section B is compressed. Imaging data, imaging data compressed in the imaging range of section C, and imaging data compressed in the imaging range of section D are obtained by the X-line sensor.

  In the present embodiment, since the imaging interval Ic is set to 3, imaging is performed at an interval of 1/60 × 3 = 1/20 s. Further, since the number of times of image capturing Kc is set to 2, image capturing by the alignment detection system AS is performed twice during the above-described relative scanning. Therefore, when the imaging range of the X-line sensor of the alignment detection AS during relative scanning is as shown in FIG. 6 and the imaging range of the section A is captured in the first imaging, in the second imaging, Imaging of the imaging range of the section D is performed. The reason why such an imaging interval can be set is to make the arrangement state of shot areas in each imaging range substantially the same (section A and section D are the arrangement of shot areas in the imaging range. Are almost the same). If the shot areas are arranged in the same imaging range in which the imaging result is actually acquired, the imaging results in the imaging range are compared and the rotation area of the wafer W is obtained to obtain the shot area in the imaging range. The influence of the difference in the arrangement state on the calculated value of the rotational component of the wafer W can be reduced. However, when such an influence can be regarded as slight, the imaging range of the section A and the imaging range of the section B may be continuously captured.

  Note that the above-described imaging during relative scanning needs to be performed in a state where the moving speed of wafer stage WST reaches a predetermined speed (V ′) (that is, at a constant speed). Therefore, in the next step 411, it is determined whether or not the scanning speed has reached a predetermined speed based on the measurement value of the wafer interferometer 18, and the processing of step 411 is repeated until the determination is affirmed. Then, when the moving speed of wafer stage WST reaches V ′, the determination in step 411 is affirmed, and the process proceeds to step 413. In step 413, an imaging data capture permission flag is set. In step 415, the process waits until the imaging data capture permission flag is reset. This imaging data capture permission flag is a flag that is referred to and reset when all imaging is completed in an interrupt process described later.

  The main controller 20 has an interrupt controller that generates interrupt signals at 1/60 s intervals in accordance with a clock signal generated by a clock provided therein. This interrupt signal is supplied to the CPU. When this interrupt signal is supplied, the CPU starts an interrupt processing routine and executes the processing. That is, the CPU executes interrupt processing at 1/60 s intervals.

  FIG. 5 shows a flowchart of the interrupt processing routine. As shown in FIG. 5, in step 501, it is first determined whether or not an imaging data capturing permission flag is set. If the determination is affirmed, the process proceeds to step 503. If the determination is negative, the interrupt process is directly exited, and the process that was being executed before the interrupt process is returned. That is, in this interrupt process, the process ends without performing any substantial process such as the imaging process until the imaging data capture permission flag is set in step 413 (FIG. 4). In step 413 (FIG. 4), after the imaging data capture permission flag is set, the determination in step 501 is affirmed, and processing after step 503, that is, imaging processing and the like are performed.

  In step 413 (FIG. 4), when the imaging data capture permission flag is set, in the interrupt process started thereafter, the determination in step 501 is affirmed, and the process proceeds to step 503. In step 503, it is determined whether the value of the counter I is Ic. If this determination is affirmed, the process proceeds to step 505. If the determination is negative, the process proceeds to step 515. Here, since the value of the counter I is set to Ic in step 407 (FIG. 4), the determination is affirmed and the process proceeds to step 505. In step 505, the alignment detection system AS is instructed to take an image. In response to this instruction, the alignment detection system AS starts imaging and sends an imaging signal as the imaging result to the main controller 20.

  In the next step 507, the measured value of the wafer interferometer 18 is acquired and stored in the storage device. In the next step 509, the counter value K is incremented by 1, and the counter value I is initialized to 0. In step 511, it is determined whether or not the counter value K is Kc. If the determination is affirmed, the process proceeds to step 513, and if the determination is negative, the interrupt process is exited. Here, since K = 1 still, the determination is denied and the interrupt processing is left as it is.

  After exiting the interrupt process, the CPU repeats the process of step 415 in FIG. 4 again. Here, since the imaging data capture permission flag remains set, the determination is negative and the processing of step 415 is repeated. The main controller 20 associates the data of the imaging signal with the measurement value of the wafer interferometer 18 stored in step 507 after the reception of the imaging signal sent from the alignment detection system AS is completed. It is assumed that processing for saving is also performed.

  When the interrupt controller supplies an interrupt signal to the CPU again, the CPU executes the interrupt process shown in FIG. 5 again. As described above, since the imaging data capturing permission flag remains set, the determination in step 501 is affirmed, and the process proceeds to step 503. In step 503, since the value of the counter value I is 0, the determination is negative and the process proceeds to step 515. In step 515, the counter value I is incremented by 1, and then the interrupt process is exited.

  Thereafter, every time interrupt processing is started every 1/60 s, the counter value I becomes Ic in step 503, and the counter value I is incremented by 1 in step 515 until the determination is affirmed.

  When the counter value I becomes Ic, the determination in step 503 is affirmed, and the imaging instruction in step 505, the measurement value of the wafer interferometer 18 in step 507 are fetched, and the counter value is updated in step 509. The imaging signal sent from the alignment detection system AS and the measurement value of the wafer interferometer 18 are stored in the storage device as the second imaging result and position. In FIG. 6, the imaging range of the section D as the imaging range of the alignment detection system AS in the second imaging is indicated by a thick dotted line.

  Returning to FIG. 5, in the next step 511, it is determined whether or not the counter value K is Kc. In step 513, since K = 2, the determination is affirmed and the process proceeds to step 513.

In step 513, the imaging data capture permission flag is reset, and then the interrupt processing is exited. Thereafter, returning to FIG. 4, the determination in step 415 is affirmed, and the process proceeds to step 417. In step 417, to terminate the relative scanning on the scribe line L? _J.

  FIG. 7 shows the imaging range of the section A captured by the X-line sensor of the alignment detection system AS at the time of relative scanning and the data string function P1 (X) corresponding to the imaging signal as the imaging result of the imaging range. The relationship is shown. In general, the brightness when shooting a shot area is low, and the brightness when shooting on a scribe line is high. Therefore, the imaging range of the X-line sensor by relative scanning is as shown in FIG. In this case (hatched lines indicate shot areas), the imaging signal acquired by the X-line sensor is as shown by P1 (X) in FIG. 7B.

Returning to FIG. 4, in the next step 419, information on the scribe line Lβ _j is detected from the imaging result. For example, data string functions P1 (X) and P2 (X) shown in FIGS. 8A and 8B are obtained from the first and second imaging results by the X-line sensor, respectively. And In this case, first, with respect to P1 (X) and P2 (X), positions in the X-axis direction (respectively X1 and X2) at which the respective folding correlations are maximum are obtained. Then, a difference LX (= X2−X1) between X1 and X2 is calculated. This difference LX becomes information regarding the scribe line Lβ _j .

  In step 421, the movement distance LY of wafer stage WST between the first imaging and the second imaging is calculated. When LY acquires the first imaging data, the measurement value in the Y-axis direction of the wafer interferometer 18 stored in the storage device corresponding to the imaging result and the second imaging data are acquired. Then, it is derived from the difference from the measured value in the Y-axis direction of the wafer interferometer 18 stored in the storage device corresponding to the imaging result.

  In step 423, the rotation angle Ry of the wafer W shown in FIG. 8C (the rotation component of the array coordinate system with respect to the stage coordinate system, and the “position information of the object (wafer)” shown in FIG. One of them).

求められたウエハＷの回転成分Ｒｙは、記憶装置に保存される。

The obtained rotation component Ry of the wafer W is stored in the storage device.

  In the next step 425, the offset amount of the wafer W (one of "position information of the object (wafer)") is calculated. Specifically, the imaging result of the area including the wafer Y mark MY (i, j) as the search alignment mark by the alignment detection system AS and the mark MY (i, j) stored in the storage device are imaged. Based on the measurement value of the wafer interferometer 18 obtained from time to time, the position of the mark is detected. Here, if the measured value of the position coordinate of the wafer Y mark MY (i, j) is (x, y) and the design value is (xid, yid), the offset amount (ofx, ofy) of the wafer W is It is obtained using the following formula. In the following formula, θ = Ry.

そして、ステップ４２５を終了後、サブルーチン３１１の処理を終了し、図３のステップ３１９に戻る。

Then, after completing step 425, the processing of subroutine 311 is terminated, and the process returns to step 319 of FIG.

  In step 319, the counter value h is initialized to 1. In step 321, the wafer stage WST is driven so that the h-th alignment mark falls within the detection field of the alignment detection system AS, and the alignment detection system AS is used. Then, each of the alignment marks in the h-th EGA measurement shot area is imaged. Here, since h = 1, the alignment mark of the first measurement shot falls within the detection visual field of the alignment detection system AS.

  Regarding the movement of wafer stage WST at this time, in addition to the design position coordinates of the h-th alignment mark stored in advance in the storage device, the rotation component Ry of wafer W obtained in step 423, the wafer The value of the offset component (ofx, ofy) of W is taken into consideration.

  When the imaging signal of the alignment mark is received from the alignment detection system AS, the position information of the first alignment mark is detected based on the imaging signal. Then, the position information of the first alignment mark is calculated from the position information and the position information of the wafer stage WST sent from the wafer interferometer 18 when the first alignment mark is imaged, and stored in the main memory. Remember.

  In the next step 323, it is determined whether or not the counter value h has exceeded the number of EGA measurement shots. If the determination is positive, the process proceeds to step 327, and if the determination is negative, the process proceeds to step 325. Here, since h = 1 still, the determination is denied and the process proceeds to step 325.

  In step 325, the counter value h is incremented by 1 (h ← h + 1), and the process returns to step 321.

  Thereafter, in step 323, until the determination is affirmed, the positions of alignment marks for the number of shots for which the processing of step 321 → step 323 → step 325 has been repeatedly executed are detected according to the optimized movement sequence.

  In step 327, based on the alignment mark detection result, so-called EGA calculation is performed in which the array coordinates of all shot areas are calculated by the statistical processing method performed in the above-described EGA method. Thereby, arrangement coordinates on the stage coordinate system (stationary coordinate system) of all shot areas on the wafer W are calculated. Since this process is disclosed in, for example, Japanese Patent Laid-Open No. 61-44429, detailed description thereof is omitted.

  In the next step 329, 1 is set to the counter g indicating the array number of the shot area, and the first shot area is set as the exposure target area.

  In step 331, based on the alignment coordinates of the exposure target area calculated by the EGA calculation, wafer stage WST is set so that the position of wafer W becomes the acceleration start position for exposing the exposure target area on wafer W. , And the reticle stage RST is moved via the stage control device 19 and the reticle stage drive unit (not shown) so that the position of the reticle R becomes the acceleration start position.

  In step 333, relative scanning of reticle stage RST and wafer stage WST is started. When both stages reach their respective target scanning speeds and reach a constant speed synchronization state, the pattern area of the reticle R starts to be illuminated by the illumination light IL from the illumination system 10, and scanning exposure is started. Then, different areas of the pattern area of the reticle R are sequentially illuminated with the illumination light IL, and the scanning exposure is completed when the illumination on the entire pattern area is completed. Thereby, the pattern of the reticle R is reduced and transferred to the exposure target area on the wafer W via the projection optical system PL.

  In step 335, with reference to the counter value g, it is determined whether or not exposure has been performed on all shot areas. Here, since g = 1, that is, only the first shot area has been exposed, the determination at step 335 is denied and the routine proceeds to step 337.

  In step 337, the value of the counter g is incremented (+1), the next shot area is set as an exposure target area, and the process returns to step 331.

  Thereafter, the processing and determination of Step 331 → Step 333 → Step 335 → Step 337 are repeated until the determination in Step 335 is affirmed.

  When the transfer of the pattern to all shot areas on the wafer W is completed, the determination in step 335 is affirmed, and the process proceeds to step 339.

  In step 339, an unloading of the wafer W is instructed to a wafer loader (not shown). Then, the wafer W is unloaded from the wafer holder 25 by a wafer loader (not shown), and then transferred to a coater / developer (not shown) connected inline to the exposure apparatus 100 by a wafer transfer system (not shown). The Thereby, the exposure processing operation ends.

  In the present embodiment, the movement distance LY of wafer stage WST is obtained based on the measurement value of wafer interferometer 18 acquired during imaging. However, the present invention is not limited to this, and the movement speed V ′ of wafer stage WST is determined. The calculated movement distance obtained by multiplying the above-described imaging interval 1/60 × Kc (here, Kc = 3) may be used as LY.

  Further, in the present embodiment, the difference LX between the mirror symmetry positions X1 and X2 of the obtained data string functions P1 (X) and P2 (X) is calculated using the folded correlation calculation of P1 (X) and P2 (X). The rotation component Ry of the wafer W was obtained, but the present invention is not limited to this. For example, the correlation between the data string function P1 (X) and the data string function P2 (X) is sequentially obtained while shifting the data string function P1 (X) pixel by pixel in the + X direction, and the correlation is maximized. The length obtained by shifting the data string function P1 (X) until that time may be obtained as LX, and the rotation component Ry of the wafer W may be obtained by calculating the above equation (1) using the obtained LX.

Further, in the present embodiment, prior to imaging of the scribe line L? _J, it was subjected to imaging of the search mark MY (i, j), after performing imaging scribe lines L? _J, search mark MY (i, j ) May be performed. That is, the search mark may be imaged either before or after the relative scanning in the Y-axis direction.

  In the present embodiment, the number of times of imaging in one relative scan is two, but may be three or more. In this case, since three or more data sequence functions are obtained (for each imaging result), the maximum likelihood estimation method (for example, based on the X position obtained by the above-described correlation from the data sequence functions (for example, The rotation component Ry of the wafer W may be obtained using a least square method.

In the present embodiment, the scribe line as the reference line to be imaged is the scribe line Lβ _j and the moving direction (predetermined direction) of wafer stage WST at the time of relative scanning is the Y-axis direction. Instead, the wafer stage WST may be moved in the X-axis direction, and the scribe line Lα _i may be the imaging target. In this case, for the calculation of the rotation component of the wafer W, the imaging result of the Y line sensor is used instead of the imaging result of the X line sensor.

In the present embodiment, the orthogonality of the X and Y coordinate axes of the stage coordinate system of wafer stage WST may be obtained by detecting both scribe lines Lα _i and Lβ _j .

That is, imaging is performed by relatively scanning wafer stage WST in the X-axis direction and Y-axis direction, respectively, and wafer W obtained based on the information about each of scribe lines Lα _i and Lβ _j obtained for each imaging result, respectively. May be obtained as Rx and Ry, and the difference ω = Rx−Ry may be obtained as the orthogonality of each coordinate axis of the stage coordinate system. In consideration of the orthogonality ω thus obtained, the offset component (ofx, ofy) of the wafer W can be obtained using the following equation instead of the above equation (2).

In the above-described embodiment, the number of times of imaging is two, but the rotational component Ry of the wafer W can be obtained by setting the number of times of imaging to one. That is, as shown in FIGS. 9A and 9B, the width W _obs of the scribe line Lβ _j is measured from the data string function P1 (X). Then, the difference between the width design value W _id of the width W _obs and the scribe line L? _J of the measured scribe lines L? _J and LX, and Y position measured by the wafer interferometer 18 at the start of imaging, at the end of imaging The above equation (1) may be calculated by setting the difference from the Y position measured by the wafer interferometer 18 or 1/60 × movement speed V ′ to LY, and the rotational component Ry of the wafer W may be obtained.

  As is apparent from the above description, in this embodiment, the main control device 20, the stage control device 19, the alignment detection system AS, the wafer stage drive unit 24, and the wafer stage WST correspond to the imaging mechanism, and the main control The device 20 corresponds to a detection device and a calculation device. That is, a part of the functions of the imaging mechanism is realized by the processing of Step 409 to Step 417 (FIG. 4) and Step 501 to Step 513 (FIG. 5) performed by the CPU of the main control device 20, and Step 419 (FIG. 4). ) Realizes the function of the detection device, and the processing of step 421 to step 425 (FIG. 4) realizes the function of the calculation device. However, it goes without saying that the present invention is not limited to this.

As described above in detail, according to the position detection method of the present embodiment, the scribe line Lβ _j that defines the orientation of the wafer W is set while the imaging field of view of the alignment detection system AS is scanned relative to the wafer W. The area to be included is continuously imaged at least once. In this way, the information on the scribe line Lβ _j (orientation) is repeated without repeating the imaging field of view movement and stationary operation (that is, the stepping operation of wafer stage WST) a plurality of times as in the prior art. Since the rotation component of the wafer W can be detected based on the information, the rotation component of the wafer W can be detected in a short time.

  In the above embodiment, the alignment detection system AS of the exposure apparatus 100 is a detection system provided with a line sensor (X line sensor and Y line sensor) composed of a one-dimensional CCD or the like arranged in the X axis direction and the Y axis direction, respectively. However, the present invention is not limited to this, and a detection system including a sensor composed of a two-dimensional CCD can also be used as the alignment detection system.

  Such a two-dimensional CCD corresponds to a standard television format system (number of pixels: 494 × 768) such as the NTSC (National TV Standards Committee) system, and is one two-dimensional CCD at 1 / 60s intervals. An image can be obtained. Therefore, even when a two-dimensional CCD is adopted, it is not necessary to change the above-described operation of the present embodiment, that is, the imaging processing by interrupt processing every 1/60 s, but the obtained image is slightly different from the one-dimensional CCD. Therefore, the processing content for the obtained imaging result is different. Hereinafter, processing contents for the imaging result when the alignment detection system AS of the two-dimensional CCD is used will be described.

  FIG. 10A, FIG. 10B, and FIG. 10C show an example of the imaging range and imaging results of the two-dimensional CCD alignment detection system AS. In the case of a two-dimensional CCD, the imaging field of view of the alignment detection system AS moves from the area A1 indicated by the dotted line to the area A2. As a result, the imaging range of the alignment detection system AS is as shown in FIG. 10A, and the image captured by the two-dimensional CCD of the alignment detection system AS is as shown in FIG. The imaging range shown in FIG. 10A is a two-dimensional image that is compressed in a direction corresponding to the Y-axis direction that is the scanning direction. Further, when the luminance of the compressed two-dimensional image shown in FIG. 10B is accumulated in the Y-axis direction, the data string function P (X of the accumulated luminance value as shown in FIG. 10C is obtained. ) Can be created.

  Several methods are conceivable for obtaining the rotational component Ry of the wafer W from the imaging result of such a two-dimensional CCD.

  For example, similarly to the alignment detection system AS of the one-dimensional CCD, imaging is performed twice during relative scanning, and the rotation component Ry of the wafer W can be obtained from the imaging results of each time. For this, as shown in FIGS. 11A and 11C, the luminance of each pixel in each image as the imaging result during the relative scanning imaged by the two-dimensional CCD is expressed as Y in the scanning direction. The accumulated luminance value data string function P1 (X) shown in FIG. 11B and the accumulated luminance value data string function P2 (X) shown in FIG. Create each one. Then, the mirror symmetry positions X1 and X2 of the data string functions P1 (X) and P2 (X) and the difference LX between them are obtained, and the movement distance LY of the wafer stage WST at the imaging interval is obtained and obtained in the same manner as this embodiment. If the above equation (1) is calculated using the obtained LX and LY, the rotation component Ry of the wafer W can be obtained.

  Further, the rotational component Ry of the wafer W can be obtained even if the imaging during relative scanning is performed only once. For example, as shown in FIG. 11 (E), in a two-dimensional image obtained by one imaging, the two regions (indicated by dotted lines) in the Y-axis direction are in the direction corresponding to the Y-axis direction. Accumulated luminance values are obtained for each pixel column. Then, in the same manner as the data sequence function P (X) shown in FIG. 10C, the data sequence functions P1 ′ (X) and P2 ′ (X) of the accumulated luminance values in the direction corresponding to the X-axis direction. (Shown in FIGS. 11 (F) and 11 (G), respectively), and based on the mirror symmetry positions X1 and X2 of the data string functions P1 ′ (X) and P2 ′ (X), The difference LX is obtained, the distance LY (shown in FIG. 11E) corresponding to the Y-axis direction of the two regions is obtained, and the above equation (1) is calculated using these LX and LY. For example, the rotational component Ry of the wafer W can be obtained. Note that in FIG. 11E, a partial area in the two-dimensional image is extracted and the luminance of each pixel in each extracted area is accumulated, but the two-dimensional image has two or more numbers. It is also possible to divide the brightness of each pixel in each region and accumulate the luminance of each pixel. When the number of divisions is 3 or more, as described above, the maximum likelihood estimation method (for example, the least square method) is used.

  In the alignment detection system AS in the above embodiment, an imaging device including a CCD is used as a sensor. However, the present invention is not limited to this, and the present invention is not limited to this. And the like, and any storage type imaging device that can output an imaging signal corresponding to the magnitude of the accumulated charge or the like is applicable.

  In the above embodiment, the case where the present invention is applied to a step-and-scan type scanning exposure apparatus has been described, but it is needless to say that the scope of the present invention is not limited to this. That is, it can be suitably applied to a step-and-repeat method, a step-and-stitch method, a mirror projection aligner, and a photo repeater. Further, the projection optical system PL may be any of a refraction system, a catadioptric system, and a reflection system, and may be any one of a reduction system, an equal magnification system, and an enlargement system.

Further, although the light source of the exposure apparatus to which the present invention is applied is a KrF excimer laser, an ArF excimer laser, or an F ₂ laser, other pulse laser light sources in the vacuum ultraviolet region may be used. In addition, as the illumination light for exposure, for example, a fiber doped with, for example, erbium (or both erbium and ytterbium) with a single wavelength laser beam in the infrared region or visible region oscillated from a DFB semiconductor laser or fiber laser. Harmonics that are amplified by an amplifier and wavelength-converted to ultraviolet light using a nonlinear optical crystal may be used.

  An illumination optical system, a projection optical system, and an alignment detection system composed of a plurality of lenses are incorporated into the exposure apparatus body for optical adjustment, and a reticle stage and wafer stage consisting of a large number of mechanical parts are incorporated into the exposure apparatus body. The exposure apparatus of the above-described embodiment can be manufactured by attaching and connecting wirings and pipes and further performing general adjustment (electrical adjustment, operation check, etc.). The exposure apparatus is preferably manufactured in a clean room where the temperature, cleanliness, etc. are controlled.

  The present invention is not limited to an exposure apparatus for manufacturing a semiconductor, but is used for manufacturing a display including a liquid crystal display element. An exposure apparatus for transferring a device pattern onto a glass plate and a device used for manufacturing a thin film magnetic head. The present invention can also be applied to an exposure apparatus that transfers a pattern onto a ceramic wafer, an exposure apparatus used for manufacturing an image sensor (CCD, etc.), an organic EL, a micromachine, and a DNA chip. Further, in order to manufacture reticles or masks used in not only microdevices such as semiconductor elements but also light exposure apparatuses, EUV exposure apparatuses, X-ray exposure apparatuses, electron beam exposure apparatuses, etc., glass substrates or silicon wafers, etc. The present invention can also be applied to an exposure apparatus that transfers a circuit pattern. Here, in an exposure apparatus using DUV (far ultraviolet) light, VUV (vacuum ultraviolet) light, or the like, a transmission type reticle is generally used. As a reticle substrate, quartz glass, fluorine-doped quartz glass, fluorite, Magnesium fluoride or quartz is used. Further, in a proximity type X-ray exposure apparatus or an electron beam exposure apparatus, a transmission mask (stencil mask, membrane mask) is used, and a silicon wafer or the like is used as a mask substrate.

  In addition, the position detection method according to the present invention is not limited to an exposure apparatus, and an object on which a reference line that defines the direction is formed is a processing target, and the apparatus needs to detect the direction of the object. Applicable.

<Device manufacturing method>
Next, an embodiment of a device manufacturing method using the exposure apparatus 100 described above in a lithography process will be described.

  FIG. 12 shows a flowchart of a manufacturing example of a device (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin film magnetic head, a micromachine, etc.). As shown in FIG. 12, first, in step 801 (design step), device function / performance design (for example, circuit design of a semiconductor device) is performed, and a pattern design for realizing the function is performed. Subsequently, in step 802 (mask manufacturing step), a mask on which the designed circuit pattern is formed is manufactured. On the other hand, in step 803 (wafer manufacturing step), a wafer is manufactured using a material such as silicon.

  Next, in step 804 (wafer processing step), using the mask and wafer prepared in steps 801 to 803, an actual circuit or the like is formed on the wafer by lithography or the like, as will be described later. Next, in step 805 (device assembly step), device assembly is performed using the wafer processed in step 804. Step 805 includes processes such as a dicing process, a bonding process, and a packaging process (chip encapsulation) as necessary.

  Finally, in step 806 (inspection step), inspections such as an operation confirmation test and a durability test of the device created in step 805 are performed. After these steps, the device is completed and shipped.

  FIG. 13 shows a detailed flow example of step 804 in the semiconductor device. In FIG. 13, in step 811 (oxidation step), the surface of the wafer is oxidized. In step 812 (CVD step), an insulating film is formed on the wafer surface. In step 813 (electrode formation step), an electrode is formed on the wafer by vapor deposition. In step 814 (ion implantation step), ions are implanted into the wafer. Each of the above steps 811 to 814 constitutes a pre-processing process in each stage of the wafer processing, and is selected and executed according to a necessary process in each stage.

  At each stage of the wafer process, when the above pre-process is completed, the post-process is executed as follows. In this post-processing process, first, in step 815 (resist formation step), a photosensitive agent is applied to the wafer. Subsequently, in step 816 (exposure step), the circuit pattern of the mask is transferred to the wafer using the exposure apparatus 100 of the above embodiment. Next, in step 817 (development step), the exposed wafer is developed, and in step 818 (etching step), the exposed member other than the portion where the resist remains is removed by etching. In step 819 (resist removal step), the resist that has become unnecessary after the etching is removed.

  By repeatedly performing these pre-processing steps and post-processing steps, multiple circuit patterns are formed on the wafer.

  By using the device manufacturing method of the present embodiment described above, the exposure apparatus 100 of the above-described embodiment is used in the exposure step (step 816), so that an improvement in throughput can be realized. As a result, it becomes possible to produce a device with a higher degree of integration.

  As described above in detail, the position detection apparatus and position detection method of the present invention are suitable for detecting position information of an object. The exposure method of the present invention is suitable for transferring a pattern to an object held on a moving body. The device manufacturing method of the present invention is suitable for the production of micro devices.

It is a figure which shows schematic structure of the exposure apparatus which concerns on one Embodiment of this invention. FIG. 2A is a diagram showing the arrangement of shot areas on the wafer, and FIG. 2B is a diagram showing the arrangement of marks on the wafer. It is a flowchart which shows the process algorithm of CPU of the main control apparatus in the case of the exposure process in the exposure apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the process of the subroutine of search alignment. It is a flowchart which shows an interruption process. It is a figure which shows a mode that the imaging visual field of an alignment detection system carries out relative scanning on the wafer. It is a figure which shows an example of the imaging range of the alignment detection system at the time of relative scanning, and an imaging result. It is a figure which shows an example of the data sequence function of imaging data. It is a figure for demonstrating the method to calculate the rotation component of a wafer by one imaging. It is a figure which shows the relationship between the imaging range by a two-dimensional CCD, an imaging result, and the data sequence function of a cumulative luminance value. It is a figure for demonstrating calculation of the rotation component of a wafer from the image of a two-dimensional CCD. It is a flowchart for demonstrating embodiment of the device manufacturing method which concerns on this invention. It is a flowchart of the process in step 804 of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 ... Main control apparatus, 100 ... Exposure apparatus, AS ... Alignment detection system, MX (i, j), MY (i, j) ... Alignment mark, L (alpha) _i , L (beta) _j ... Scribe line, S ... Shot area | region, W ... Wafer, WST ... wafer stage.

Claims (21)

A position detection device for detecting position information of an object,
A storage-type imaging device;
Using the storage-type imaging device, a region including a reference line that defines the orientation of the object formed on the object while relatively scanning the imaging field of the storage-type imaging device in a predetermined direction with respect to the object. An imaging mechanism for acquiring an imaging result of a region including the reference line compressed in the predetermined direction by continuously imaging at least once;
A detection device that detects information related to the reference line based on an imaging result of an area including the reference line;
A position detection device comprising: a calculation device that calculates information about the orientation of the object based on the detected information about the reference line and the relative scanning speed . The imaging mechanism is
At the start or end of the relative scanning, the storage-type imaging device is used to further image a region including a mark with known design position information formed on the object,
The detection device includes:
Further detecting the position information of the mark based on the imaging result of the region including the mark,
The calculation device includes:
The position information of the object is further calculated based on the detected position information of the mark, the information on the orientation of the object, and the design position information of the detected mark. The position detection device described. A position detection device for detecting position information of an object,
A storage-type imaging device;
Using the storage-type imaging device, a region including a reference line that defines the orientation of the object formed on the object while relatively scanning the imaging field of the storage-type imaging device in a predetermined direction with respect to the object. To obtain an imaging result of an area including the reference line compressed in the predetermined direction, and at the start or end of the relative scanning, using the storage type imaging device. An imaging mechanism for further imaging an area including a mark formed on the object and having known design position information;
A detection device that detects information on the reference line based on an imaging result of an area including the reference line, and further detects position information of the mark based on an imaging result of the area including the mark;
Based on information on the detected reference line, information on the direction of the object is calculated, position information on the detected mark and information on the direction of the object, and a design position of the detected mark And a calculation device that further calculates position information of the object based on the information. The imaging mechanism is
The directions of the respective coordinate axes of the two-dimensional coordinate system that defines the movement of the object are set as the predetermined directions, respectively, and the two reference points orthogonal to each other while the imaging field of view of the storage-type imaging device is scanned relative to the object A region including the reference line extending substantially parallel to the direction of each coordinate axis in the line is continuously imaged at least once using the storage type imaging device,
The detection device includes:
Based on the imaging result including each of the reference lines, information about the reference line is detected,
The calculation device includes:
Further calculating the orthogonality of each coordinate axis of the two-dimensional coordinate system based on the detected information on each reference line, and calculating the information on the positional deviation of the object while taking the orthogonality into account. The position detection device according to claim 2 or 3 , characterized in that The storage type imaging device includes:
An imaging device in which a plurality of photoelectric conversion elements are two-dimensionally arranged on an imaging surface;
The detection device includes:
In a plurality of regions in the two-dimensional image obtained as the imaging result, a cumulative value of luminance data for each pixel column in a direction corresponding to the predetermined direction is obtained, and data of the cumulative value in the orthogonal direction of the corresponding direction is obtained. The position detection according to any one of claims 1 to 4 , wherein a column is created for each region, and information relating to the reference line is detected for a data row of accumulated values of the created regions. apparatus. The storage type imaging device includes:
An imaging device in which a plurality of photoelectric conversion elements are two-dimensionally arranged on an imaging surface;
The detection device includes:
A plurality of pixel columns in a direction orthogonal to the direction corresponding to the predetermined direction are extracted from the two-dimensional image obtained as the imaging result, and information on the reference line is obtained on the basis of the data string of luminance data of each extracted pixel column It detects, The position detection apparatus as described in any one of Claims 1-4 characterized by the above-mentioned. The imaging mechanism is
During the predetermined direction of relative scanning, by conducting a continuous imaging of multiple, it claims 1-4, characterized in that acquires a plurality of image pickup results of the region including the reference line which is compressed in the predetermined direction The position detection device according to any one of the above. The storage type imaging device includes:
The position detection apparatus according to claim 7 , wherein the plurality of photoelectric conversion elements are imaging devices arranged in a row on a imaging surface in a direction corresponding to a direction orthogonal to the predetermined direction. The storage type imaging device includes:
A plurality of photoelectric conversion elements are imaging devices arranged two-dimensionally on the imaging surface,
The detection device includes:
In a predetermined region in the two-dimensional image obtained as the imaging result, a cumulative value of luminance data for each pixel column in a direction corresponding to the predetermined direction is obtained, and a data string of the cumulative value in the orthogonal direction of the corresponding direction The position detection device according to claim 7 , wherein information on the reference line is detected based on the generated data string. The storage type imaging device includes:
An imaging device in which a plurality of photoelectric conversion elements are two-dimensionally arranged on an imaging surface;
The detection device includes:
A pixel row in a direction orthogonal to the direction corresponding to the predetermined direction is extracted from the two-dimensional image obtained as the imaging result, and information on the reference line is detected based on the data row of luminance data of the extracted pixel row The position detection device according to claim 7 . The reference line is a boundary line between a plurality of partitioned areas arranged in a matrix on the object,
11. The imaging mechanism according to claim 7 , wherein the imaging mechanism performs imaging each time at an interval such that an arrangement state of the partition regions corresponding to each imaging result is substantially the same. Position detection device. When the imaging mechanism performs imaging at the time of relative scanning in the predetermined direction three times or more,
The detection device includes:
The position detection device according to any one of claims 7 to 11 , wherein information on the reference line is detected by maximum likelihood estimation based on each imaging result. The detection device includes:
The position detection apparatus according to any one of claims 1 to 12, wherein information on the reference line is detected on the basis of a folded correlation of a data string. The detection device includes:
The position detection apparatus according to claim 1, wherein information on the reference line is detected based on correlation between different data strings. A position detection device for detecting position information of an object,
A storage-type imaging device;
Using the storage-type imaging device, a region including a reference line that defines the orientation of the object formed on the object while relatively scanning the imaging field of the storage-type imaging device in a predetermined direction with respect to the object. An imaging mechanism for acquiring an imaging result of a region including the reference line compressed in the predetermined direction by continuously imaging at least once;
A detection device that detects information related to the reference line based on an imaging result of an area including the reference line;
A position detection device comprising: a calculation device that calculates information related to the orientation of the object based on the detected information related to the reference line and a design value of information related to the reference line. The imaging mechanism is
At the start or end of the relative scanning, the storage-type imaging device is used to further image a region including a mark with known design position information formed on the object,
The detection device includes:
Further detecting the position information of the mark based on the imaging result of the region including the mark,
The calculation device includes:
The position information of the object is further calculated based on the detected position information of the mark, the information on the orientation of the object, and the design position information of the detected mark. The position detection device described. The imaging mechanism is
The directions of the respective coordinate axes of the two-dimensional coordinate system that defines the movement of the object are set as the predetermined directions, respectively, and the two reference points orthogonal to each other while the imaging field of view of the storage-type imaging device is scanned relative to the object A region including the reference line extending substantially parallel to the direction of each coordinate axis in the line is continuously captured at least once using the storage type imaging device,
The detection device includes:
Based on the imaging result including each of the reference lines, each detects information on the reference line,
The calculation device includes:
Further calculating the orthogonality of each coordinate axis of the two-dimensional coordinate system based on the detected information on each reference line, and calculating the information on the positional deviation of the object while taking the orthogonality into account. The position detection device according to claim 16, wherein A position detection device for detecting position information of an object,
A storage-type imaging device;
Using the storage-type imaging device, a region including a reference line that defines the orientation of the object formed on the object while relatively scanning the imaging field of the storage-type imaging device in a predetermined direction with respect to the object. Continuously at least once to obtain an imaging result of the region including the reference line compressed in the predetermined direction, using the storage type imaging device at the start or end of the relative scanning, An imaging mechanism that further images an area including a mark formed on the object and whose position information on the design is known, and acquires an imaging result of the area including the mark;
A detection device that detects information on the orientation of the reference line based on an imaging result of the region including the reference line, and further detects position information of the mark based on the imaging result of the region including the mark;
A position detecting device comprising: a calculation device that calculates position information of the object based on information on the detected direction of the reference line, position information of the mark, and position information on the design of the detected mark. . A position detection method for detecting position information of an object,
A position detection method including a step of detecting position information of an object using the position detection device according to any one of claims 1 to 18 . An exposure method for transferring a pattern onto an object held on a moving body,
Detecting the position information of the object on the moving body using the position detecting method according to claim 19 ;
And a step of transferring the pattern to the object while controlling the position of the object held by the moving body based on the detected position information of the object. In a device manufacturing method including a lithography process,
21. A device manufacturing method, wherein exposure is performed using the exposure method according to claim 20 in the lithography process.

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