JP2007287898A - Mark member, measuring method, measuring apparatus, and aligner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the base line measuring accuracy of a sensor. <P>SOLUTION: On a reference mark plate FM, four reference marks WM<SB>1</SB>, WM<SB>2</SB>, WM<SB>3</SB>, WM<SB>4</SB>for measuring the base line of an alignment system ALG are disposed in such a layout that the mean position of these marks aligns with the position of a measuring pattern ST for detecting a reticle alignment mark RM. Hence, if the mutual distances between the reference marks WM<SB>1</SB>, WM<SB>2</SB>, WM<SB>3</SB>, WM<SB>4</SB>or the distance between each reference mark WM<SB>1</SB>, WM<SB>2</SB>, WM<SB>3</SB>, WM<SB>4</SB>and the measuring pattern ST is changed due to the expansion/contraction of the reference mark plate FM, it is always held that the mean position of the reference marks WM<SB>1</SB>, WM<SB>2</SB>, WM<SB>3</SB>, WM<SB>4</SB>aligns with the position of the measuring pattern ST. This suppresses the measuring error from growing in the base line measurement using the reference mark WM<SB>1</SB>, WM<SB>2</SB>, WM<SB>3</SB>, WM<SB>4</SB>and the measuring pattern ST. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a mark member, a measurement method, a measurement apparatus, and an exposure apparatus. More specifically, the present invention relates to a mark member used for measuring a positional relationship between sensors, and a sensor baseline is measured using the mark member. The present invention relates to a measurement method, a measurement device that measures a baseline of a sensor using the mark member, and an exposure apparatus including the measurement device.

  Conventionally, in a lithography process for manufacturing an electronic device such as a semiconductor element (such as an integrated circuit) or a liquid crystal display element, a resist (sensitive material) is applied to a pattern image of a mask (or reticle) via a projection optical system. A step-and-repeat reduction projection exposure apparatus (so-called stepper) for transferring to each of a plurality of shot areas on a sensitive object such as a wafer or a glass plate (hereinafter collectively referred to as “wafer”); An AND-scan type projection exposure apparatus (a so-called scanning stepper (also called a scanner)) or the like is mainly used.

  When manufacturing a semiconductor element or the like with this type of exposure apparatus, it is necessary to form different circuit patterns on the wafer so that the reticle and wafer are formed when forming the second and subsequent circuit patterns. It is necessary to perform alignment (alignment) of the circuit pattern formed in the shot area with high accuracy. For this alignment, in recent years, relatively many off-axis type alignment sensors that detect alignment marks on a wafer without using a projection optical system are used.

  By the way, in order to position each shot area on the wafer at the exposure position using an off-axis alignment sensor, it is necessary to measure the baseline of the alignment sensor prior to exposure.

  In this baseline measurement, the projection position of the reticle pattern is determined by measuring the aerial image (projected image) of the reticle alignment mark whose positional relationship with the circuit pattern formed on the reticle is known on the image plane side of the projection optical system. Recently, measurement has been carried out. For the baseline measurement of the alignment sensor, it is necessary that the measurement pattern (slit-like opening pattern) constituting a part of the aerial image measurement device and the reference mark detected by the alignment sensor be formed on the same object. is there. This is because the baseline is calculated on the assumption that the relationship between the measurement pattern and the reference mark is known and fixed.

  Therefore, for example, when the slit-shaped opening pattern is formed on the reference mark plate on which the reference mark is formed, it is desirable that the reference mark plate is made of a material that is not easily deformed (thermal expansion or the like) due to a temperature change or the like. However, when forming a slit for aerial image measurement, it is difficult to use a low thermal expansion material because a material that transmits exposure light must be selected.

  Since the baseline measurement error due to the thermal expansion of the reference mark plate is considered to be proportional to the distance between the slit-shaped opening pattern and the reference mark, the measurement error can be reduced by placing them as close as possible. It is possible to plan. However, if a reference mark (formed by extracting a part of the metal film into a mark shape) is placed at a position close to the slit-shaped opening pattern on the reference mark plate, the mark part (the part without the light shielding metal film) There is a possibility that the light transmitted through the light enters the light receiving system of the aerial image measurement device and causes an error in aerial image measurement. For this reason, other patterns cannot be formed in the vicinity of the slit-shaped opening pattern, for example, in a range of about 10 mm.

  For this reason, when the slit-shaped opening pattern is formed on the reference mark plate on which the reference mark is formed, there is a possibility that a baseline measurement error may occur due to expansion / contraction of the reference mark plate or a rotation error.

  Here, for convenience, description will be made with reference to the configuration according to the embodiment corresponding to each component, but the present invention is not limited to the embodiment.

From a first viewpoint, the present invention is a mark member used for measuring a positional relationship between a plurality of sensors, and is a mark for at least one first sensor used for measurement using the first sensor. (ST) and at least three second sensor marks (WM _{1 to} WM ₄ ) used for measurement using the second sensor are the average position of the first sensor mark and the second sensor mark. This is a mark member (FM) including a pattern plate formed in an arrangement in which the average positions of the marks coincide with each other.

  According to this, at least one first sensor mark and at least three second sensor marks are formed on the pattern plate in such an arrangement that the average positions of the pattern plates coincide with each other. For this reason, isotropic deformation (expansion and contraction) and rotation error of the pattern plate do not affect the relationship between the average positions, and the relationship is maintained. Therefore, in the predetermined measurement using the mark member, it is possible to suppress the occurrence of measurement errors due to thermal deformation or rotation error of the pattern plate.

From the second viewpoint, the present invention detects the pattern image by the first sensor via the at least one first sensor mark (ST) of the mark member (FM) of the present invention, A first step of measuring position information of a pattern image; a first step of detecting an alignment mark on an object on which the pattern image is generated, using marks for each of the second sensors (WM _{1 to} WM ₄ ) of the mark member; A second step of measuring position information of the detection center of the second sensor at the time of detecting a mark for each of the second sensors by detecting each using two sensors; A third step of calculating a baseline of the second sensor based on position information of the detection center of the second sensor at the time of detecting a mark for two sensors.

  According to this, the position information of the pattern image measured by detecting the pattern image by the first sensor through the mark for the first sensor and the mark for the second sensor are detected using the second sensor. Thus, a baseline of the second sensor with respect to the first sensor is calculated based on the position information of the detection center of the second sensor at the time of detecting the mark for each second sensor. In this case, even if the pattern plate expands or contracts, the average position of the marks for the first sensor and the average position of the marks for the second sensor remain substantially the same (the relationship between the average positions is unchanged). is there). Accordingly, the base line can be accurately measured by calculating the base line based on the position information of the pattern image and the average of the position information of the detection center of the second sensor at the time of detecting the mark for each second sensor. It becomes possible.

According to a third aspect of the present invention, a pattern image on an object is first sensored via the mark member (FM) of the present invention; and the at least one first sensor mark (ST) of the mark member. The first measurement system that measures the generation position information of the pattern image by detecting the mark image, and the marks (WM _{1 to} WM ₄ ) for the second sensors of the mark member are detected as alignment marks on the object. A second measurement system for measuring position information of the detection center of the second sensor when detecting a mark for each of the second sensors by detecting each using a second sensor (ALG) used in the pattern; A calculation system (50) for calculating a base line of the second sensor based on image generation position information and position information of a detection center of the second sensor at the time of detecting the mark for each of the second sensors; It is a measuring device provided.

  According to this, the position information of the pattern image measured through the mark for the first sensor by the first detection system, and the mark for the second sensor is detected by the second sensor by the second detection system. Thus, based on the position information of the detection center of the second sensor at the time of detecting the mark for each of the second sensors, a baseline for the first sensor of the second sensor is calculated by the calculation system. In this case, even if the pattern plate expands or contracts, the average position of the marks for the first sensor and the average position of the marks for the second sensor remain substantially the same (the relationship between the average positions is unchanged). is there). Therefore, it is possible to accurately measure the baseline by calculating the baseline based on the position information of the pattern image and the average of the position information of the detection center of the second sensor at the time of detecting the mark for each second sensor. It becomes possible.

  From a fourth aspect, the present invention is an exposure apparatus that exposes an object with a pattern image, the measuring apparatus according to the present invention; and a movable body (WST) on which the object is placed and movable in a two-dimensional plane. ) And; detecting position information of an alignment mark on the object (W) placed on the moving body using the second sensor (ALG), and based on the detection result and the baseline, And a control device (50) for controlling movement of the moving body when exposing the object with a pattern image.

  According to this, when the control apparatus exposes the object with the pattern image, based on the position information of the alignment mark detected by the second sensor and the baseline measured by the measurement apparatus of the present invention, Control movement. Therefore, the positional relationship between the pattern image and the object can be accurately set to a desired relationship, and high-precision exposure can be realized.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 5B.

  FIG. 1 schematically shows a configuration of an exposure apparatus 100 according to an embodiment. The exposure apparatus 100 is a step-and-scan exposure apparatus, that is, a so-called scanner.

  The exposure apparatus 100 holds an illumination system ILS, a reticle R illuminated by exposure illumination light (hereinafter referred to as illumination light) IL from the illumination system ILS, and holds a predetermined scanning direction (here, in FIG. 1). A reticle stage RST that moves in the Y-axis direction, which is the left-right direction in the drawing), a projection unit PU that includes a projection optical system PL that projects illumination light IL emitted from the reticle R onto the wafer W, and a wafer W are placed thereon. A stage device 150 including a wafer stage WST to be performed and a measurement stage MST used for measurement for exposure, and a control system thereof are provided.

  As a light source mounted in the illumination system ILS, an ArF excimer laser light source (output wavelength 193 nm), which is a pulse light source that emits light in the vacuum ultraviolet region with a wavelength of 200 nm to 170 nm, is used as an example.

  The illumination system ILS includes a beam shaping optical system, an energy coarse adjuster, an optical integrator (a uniformizer or a homogenizer), an illumination system aperture stop plate, a beam splitter, a relay lens, and a reticle arranged in a predetermined positional relationship. It includes a blind, a mirror for bending the optical path, a condenser lens (all not shown), and the like. Note that the configuration of the illumination system ILS and the function of each optical member are disclosed in, for example, the pamphlet of International Publication No. 2002/103766, and detailed description thereof is omitted here.

  On reticle stage RST, reticle R on which a circuit pattern or the like is formed on its pattern surface (lower surface in FIG. 1) is fixed, for example, by vacuum suction. The reticle stage RST can be moved in a predetermined direction within the XY plane by a reticle stage drive system 55 including, for example, a linear motor.

  The position of the reticle stage RST in the stage movement plane (including rotation around the Z axis) is moved by a reticle laser interferometer (hereinafter referred to as “reticle interferometer”) 53 to a movable mirror 65 (actually in the Y axis direction). (A Y movable mirror having a reflecting surface orthogonal to the X moving mirror having a reflecting surface orthogonal to the X-axis direction is provided) and is always detected with a resolution of, for example, about 0.5 to 1 nm. The measurement value of the reticle interferometer 53 is sent to the main controller 50, which in the X-axis direction of the reticle stage RST through the reticle stage drive system 55 based on the measurement value of the reticle interferometer 53. , Control the position in the Y-axis direction and the θz direction (rotation direction around the Z-axis).

  The projection unit PU is disposed below the reticle stage RST. The projection unit PU includes a lens barrel 140 and a projection optical system PL composed of a plurality of optical elements held in the lens barrel 140 in a predetermined positional relationship. As the projection optical system PL, for example, a refractive optical system including a plurality of lenses (lens elements) having a common optical axis AX in the Z-axis direction is used. The projection optical system PL is, for example, both-side telecentric and has a predetermined projection magnification (for example, 1/4, 1/5, or 1/8). Therefore, when the illumination area IAR on the reticle R is illuminated by the illumination light IL from the illumination system ILS, the illumination light IL that has passed through the reticle R is illuminated via the projection optical system PL (projection unit PU). A reduced image of the circuit pattern of the reticle R in the area IAR (a reduced image of a part of the circuit pattern) is an area conjugated to the illumination area IAR on the wafer W coated with a resist (sensitive material) on the surface (hereinafter, “ (Also referred to as “exposure area”).

  In the exposure apparatus 100 of the present embodiment, an immersion apparatus is provided in the vicinity of a lens (hereinafter also referred to as “tip lens”) 191 that is an optical element on the most image plane side (wafer W side) constituting the projection optical system PL. A liquid supply nozzle 131 </ b> A and a liquid recovery nozzle 131 </ b> B constituting 132 are provided. One ends of the nozzle 131A and the nozzle 131B are connected to a liquid supply device 138 and a liquid recovery device 139 (not shown in FIG. 1, refer to FIG. 4), respectively. Then, by operating the liquid supply device 138 and the liquid recovery device 139 by the main controller 50, the liquid Lq is supplied between the tip lens 191 and the wafer W via the liquid supply nozzle 131A, and The liquid Lq is recovered from between the front lens 191 and the wafer W via the liquid recovery nozzle 131B, and a certain amount of liquid Lq is held between the front lens 191 and the wafer W. Even when the measurement stage MST is positioned below the projection unit PU, a certain amount of liquid Lq is held between a measurement table MTB and a front lens 191 described later, as described above.

  In this embodiment, as an example, pure water that transmits ArF excimer laser light (light having a wavelength of 193 nm) is used as the liquid Lq for immersion. Pure water has the advantage that it can be easily obtained in large quantities at a semiconductor manufacturing factory or the like and has less adverse effects on the resist on the wafer, optical lenses, and the like.

  On the + Y side of the projection unit PU, an off-axis alignment system (hereinafter abbreviated as “alignment system”) ALG for optically detecting a detection target mark such as an alignment mark on the wafer W is provided. . As the alignment system ALG, various types of sensors can be used, but in this embodiment, an image processing type sensor is used. The imaging signal from the alignment system ALG is supplied to the main controller 50. Note that the image processing type sensor is disclosed in, for example, Japanese Patent Laid-Open No. 4-65603, and therefore detailed description thereof is omitted here.

  The stage apparatus 150 includes a base board 112, a wafer stage WST and a measurement stage MST supported above the base board 112 via an air bearing (not shown) in a non-contact manner, and positions of these stages WST and MST. Interferometers 116 and 117 for measuring, and a stage drive system 124 for driving stages WST and MST using a linear motor or the like are provided.

  As shown in FIG. 1, wafer stage WST includes a wafer stage main body 91 in which the air bearing is provided on the bottom surface, and a wafer table WTB mounted on wafer stage main body 91. As shown in FIG. 1, the measurement stage WST includes a measurement stage main body 92 in which the air bearing is provided on the bottom surface thereof, and a measurement table MTB mounted on the measurement stage main body 92.

  Each of the stages WST and MST is driven (including θz rotation) independently of each other in the XY plane by the stage drive system 124. Interferometers 116 and 117 detect the position of wafer stage WST and measurement stage MST in the stage moving surface (XY plane) and the rotational position around each coordinate axis, respectively. The measurement values of the interferometers 116 and 117 are sent to the main controller 50. The main controller 50 determines the wafer stage WST and the measurement via the stage drive system 124 based on the measurement values of the interferometers 116 and 117, respectively. The position (and speed) of the stage MST is controlled (see FIG. 4).

  On wafer table WTB, a wafer holder (not shown) for holding wafer W by vacuum suction or the like is provided. The wafer holder includes a plate-like main body portion and a plate 93 fixed to the upper surface of the main body portion and having a circular opening having a diameter of about 0.1 to 2 mm larger than the diameter of the wafer W at the center thereof. A large number of pins are arranged in the region of the main body portion inside the large circular opening of the plate 93, and the wafer W is vacuum-sucked while being supported by the large number of pins. In this case, in the state where the wafer W is vacuum-sucked, the height of the surface of the wafer W and the surface of the plate 93 are substantially the same. The entire surface of the plate 93 is coated with a liquid repellent material (water repellent material) such as a fluorine resin material or an acrylic resin material to form a liquid repellent film. A resist (sensitive material) is applied to the surface of the wafer W, and a resist film is formed by the applied resist. In this case, it is desirable to use a resist film that is liquid repellent with respect to the immersion liquid Lq.

  A plate member 101 is held on the measurement table WTB of the measurement stage MST. As shown in FIG. 2, which is a plan view of the measurement stage MST, the plate member 101 has a square opening 101a, a rectangular opening 101b whose longitudinal direction is the X-axis direction, and two circular openings 101d and 101f. Is formed.

In the opening 101a, a square plate-like fiducial mark plate FM is arranged in a state where the upper surface thereof is set to be substantially the same height (level) as the surface of the plate member 101. The reference mark plate FM has a square plate-like quartz glass and a light shielding film such as chromium formed on the surface of the quartz glass. A slit pattern having a longitudinal direction in the Y-axis direction (hereinafter referred to as “slit” as appropriate) STx and a slit pattern having a longitudinal direction in the X-axis direction (hereinafter referred to as “slit” as appropriate) The measurement pattern ST including STy and four reference marks WM ₁ , WM ₂ , WM ₃ , and WM ₄ including a two-dimensional mark having a predetermined shape surrounding the measurement pattern ST are light transmitting portions. It is formed as.

FIG. 3 is an enlarged view of the reference mark plate FM in FIG. As shown in FIG. 3, the slit STx is formed on the + Y side of the center point P on the surface of the reference mark plate FM and on the straight line L1 passing through the center point P and parallel to the Y axis. The mark plate FM is formed on the −X side of the center point P on the surface of the mark plate FM and on the straight line L2 passing through the center point P and parallel to the X axis. These slits STx and STy have a width of, for example, 100 nm and a length of, for example, 10 μm. The centers of the slits STx and SyT are, for example, 20 μm away from the center point P in the + Y direction and the −X direction, respectively. The four reference marks WM _{1 to} WM ₄ have a cross shape as an example, and are formed on the reference mark plate FM so that the distances from the point P are equal to each other. Each of the reference marks WM ₁ and WM ₃ is formed on the −Y side and + Y side of the point P on the straight line L1, and each of the reference marks WM ₂ and WM ₄ is formed on the + X side and −X side of the point P on the straight line L2. Has been. The reference marks WM _{1 to} WM ₄ are marks having a line width of, for example, about several μm to 10 μm and a total of about 100 μm square, for example, and are formed at positions separated from the point P by, for example, about 10 mm to 15 mm.

  In the present embodiment, under the measurement slit ST of the reference mark plate FM, the illumination light IL irradiated to the plate member 101 via the projection optical system PL and the liquid Lq is received via the slit STx or STy. A light receiving system 110b (see FIG. 4) including a light receiving element such as a photomultiplier tube is provided. The reference mark plate FM and the light receiving system 110b are at least the aerial image measuring instrument 125 (see FIG. 4) disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-14005 (corresponding US Patent Application Publication No. 2002/0041377). Part of it.

  Returning to FIG. 2, an illuminance monitor (irradiation amount monitor) 122 is disposed below the opening 101 b of the plate member 101. The illuminance monitor 122 has the same configuration as the illuminance monitor (irradiation amount monitor) disclosed in, for example, Japanese Patent Laid-Open No. 6-291016 (corresponding US Pat. No. 5,721,608). The illuminance of the illumination light IL is measured on the image plane of the optical system PL.

  In the opening 101d of the plate member 101, an illuminance unevenness measuring device 104 having a circular pattern plate 103 in plan view is arranged. The illuminance unevenness measuring instrument 104 has a sensor composed of a light receiving element (not shown) (silicon photo diode or photo multiplier tube) disposed below the pattern plate 103. The pattern plate 103 is made of quartz glass or the like. A light shielding film such as chromium is formed on the surface of the pattern plate 103, and a pinhole 103a is formed as a light transmitting portion in the center of the light shielding film. The uneven illuminance measuring instrument 104 has the same configuration as the uneven illuminance measuring instrument disclosed in Japanese Patent Laid-Open No. 57-117238 (corresponding US Pat. No. 4,465,368) and the like, and has a projection optical system. Irradiance unevenness of the illumination light IL is measured via the liquid Lq on the PL image plane.

  Inside the opening 101f of the plate member 101, a wavefront aberration measuring pattern plate 107 having a circular shape in plan view is disposed in a state where the surface thereof is substantially flush with the surface of the plate member 101. Similar to the pattern plate 103, the wavefront aberration measurement pattern plate 107 includes quartz glass and a light shielding film such as chromium formed on the surface of the quartz glass, and has a circular shape at the center of the light shielding film. An opening is formed. A light receiving system including, for example, a microlens array that receives the illumination light IL through the projection optical system PL and the liquid Lq is provided below the wavefront aberration measurement pattern plate 107. The pattern plate 107 and the light receiving system constitute at least a part of the wavefront aberration measuring instrument 127 disclosed in, for example, International Publication No. 99/60361 pamphlet (corresponding to European Patent No. 1,079,223).

  Outputs (measured values) of the aerial image measuring instrument 125, the illuminance monitor 122, the illuminance unevenness measuring instrument 104, and the wavefront aberration measuring instrument 127 described above are supplied to the main controller 50.

  From the viewpoint of suppressing the influence of heat, in the aerial image measuring instrument 125, the wavefront aberration measuring instrument 127, etc., for example, only a part of the optical system or the like may be mounted on the measuring stage MST.

  FIG. 4 shows the main configuration of the control system of the exposure apparatus 100. This control system includes a main controller 50 composed of a microcomputer (or workstation) that controls the entire apparatus in an integrated manner.

  Next, a series of operations at the time of exposure in the exposure apparatus 100 of the present embodiment will be described.

  First, main controller 50 performs baseline measurement of alignment system ALG as follows prior to wafer exposure.

  First, outside the pattern area on the reticle R, for example, on one side and the other side of the pattern area on a straight line (center line) parallel to the X axis (or Y axis) passing through the center (reticle center) of the pattern area. By measuring the position of the projected image (aerial image) of the pair of reticle alignment marks, the projection center of the pattern area whose positional relationship with the reticle alignment marks is known is obtained.

  Specifically, main controller 50 drives reticle stage RST so that the center of reticle R is positioned almost directly above the optical axis of projection optical system PL. Then, main controller 50 drives a reticle blind (not shown) of illumination system ILS to limit the illumination area so that illumination light IL is emitted only to one reticle alignment mark and its surrounding area. To do. At this time, assuming that the reference mark plate FM on the measurement stage MST is below the projection optical system PL, for example, as shown in FIG. 5A, the reference mark plate FM below the projection optical system PL. An aerial image RM ′ of the reticle alignment mark is formed on the top via the projection optical system PL and the liquid Lq.

  Next, main controller 50 drives measurement stage MST in the + Y direction based on the measurement value of interferometer 117, thereby scanning slit image STy on reference mark plate FM with respect to aerial image RM '. As a result, the illumination light IL transmitted through the slit STy is received by the light receiving system 110b, and a photoelectric conversion signal is supplied to the main controller 50 from the light receiving system 110b.

FIG. 5B shows an example of a photoelectric conversion signal supplied to the main control device 50 by scanning the slit STy described above. Based on this photoelectric conversion signal, main controller 50 detects, for example, Y coordinate Y _MAX corresponding to the peak value of the photoelectric conversion signal as the Y coordinate in the stage coordinate system of the reticle alignment mark. In FIG. 5B, the horizontal axis represents the Y position of the measurement stage MST measured by the interferometer 117. Here, the stage coordinate system is a coordinate system that regulates the movement of wafer stage WST and measurement stage MST, and is a coordinate system that is defined by the measurement axis of the interferometer system including interferometers 117 and 116. Then, this stage coordinate system is called a reference coordinate system.

  Similarly, main controller 50 drives measurement stage MST along the X axis based on the measurement value of interferometer 117 to scan slit STx on reference mark plate FM with respect to aerial image RM '. Thus, in the same manner as described above, the main controller 50 determines, for example, the X coordinate corresponding to the peak value of the photoelectric conversion signal based on the photoelectric conversion signal from the light receiving system 110b in the reference coordinate system of the reticle alignment mark. Detect as coordinates.

  Next, main controller 50 obtains the Y coordinate and the X coordinate in the reference coordinate system of the other reticle alignment mark in the same procedure as described above.

  Then, main controller 50 obtains position coordinates in the reference coordinate system of the projection center of the pattern area of reticle R based on the position coordinates in the reference coordinate system of the two reticle alignment marks.

Next, main controller 50 drives measurement stage MST based on the measurement value of interferometer 117 so that fiducial mark plate FM is positioned immediately below alignment system ALG based on the known baseline design value. To do. Then, main controller 50 sequentially positions _four reference marks WM _{1 to} WM 4 formed on reference mark plate FM in the detection area of alignment system ALG, and uses reference marks WM _{1 to} WM _{4 in} alignment system ALG. Are detected sequentially. This detection is performed without going through the liquid Lq. At this time, the liquid Lq is recovered. The main control unit 50, the position of the reference mark _WM 1 _{~WM 4} for detecting the center to be detected by the alignment system ALG, and based on the measurement values of the interferometer 117 at the time of detecting each mark, the reference mark WM ₁ -WM ₄ position coordinates (X ₁ , Y ₁ ), (X ₂ , Y ₂ ), (X ₃ , Y ₃ ), (X ₄ , Y) of the detection center of the alignment system ALG in the reference coordinate system at the time of detection. ₄ ) are calculated respectively.

Next, main controller 50 determines the coordinates of the average position of the _four position coordinates (X ₁ , Y ₁ ), (X ₂ , Y ₂ ), (X ₃ , Y ₃ ), (X ₄ , Y ₄ ). (X _AVE , Y _AVE ) = ((X ₁ + X ₂ + X ₃ + X ₄ ) / 4, (Y ₁ + Y ₂ + Y ₃ + Y ₄ ) / 4), that is, the average position of the reference marks WM _{1 to} WM ₄ , that is, the reference mark Detection center of alignment system ALG when detecting a virtual mark existing at the center point P of the surface of the plate FM (the center point P of the measurement pattern ST that is the intersection of the center axis of the slit STy and the center axis of the slit STx) The position coordinates of are calculated. Here, by _obtaining the coordinates (X _AVE , Y _AVE ) of the average position, the measurement included in the measurement value of each position coordinate resulting from deformation (isotropic expansion / contraction) or rotation error of the reference mark plate FM. The error is offset. Therefore, the coordinates (X _AVE , Y _AVE ) of the average position are position coordinates in the reference coordinate system of the detection center of the true alignment system ALG including only the position shift component of the detection center of the alignment system ALG. Strictly speaking, the center of the slit STx or STy and the average position of the reference marks WM _{1 to} WM ₄ do not completely coincide (for example, 20 μm apart in this embodiment), but this disagreement is practically ignored. it can. For example, when FM expands and contracts by 1 ppm, the average position error is 0.02 nm, which is sufficiently smaller than the accuracy required for baseline measurement (for example, 1 nm).

Next, main controller 50 determines the pattern image of reticle R based on the position coordinates in the reference coordinate system of the projection center of the pattern area of reticle R previously obtained and the position coordinates (X _AVE , Y _AVE ). The positional relationship between the projected position of the image and the detection center of the alignment system ALG, that is, the baseline of the alignment system ALG is obtained.

  When the above-described baseline measurement is completed, main controller 50 performs wafer alignment such as EGA (Enhanced Global Alignment) disclosed in detail in, for example, Japanese Patent Laid-Open No. 61-44429 and the like on wafer W. The arrangement coordinates of all shot areas are obtained. In this wafer alignment, a wafer alignment mark of a predetermined sample shot among a plurality of shot areas on the wafer W is measured by the alignment system ALG.

  Next, main controller 50 determines position information from reticle interferometer 53 and interferometer 116 based on the arrangement coordinates (position information) of the shot areas on wafer W obtained above and the baseline measured earlier. , The wafer stage WST and the reticle stage RST are driven to perform step-and-scan exposure, and the circuit pattern of the reticle R is transferred to a plurality of shot areas on the wafer W, respectively. The scanning exposure in this case is performed via the projection optical system PL and the liquid Lq, and at least during a step-and-scan exposure, a certain amount of the liquid Lq is present between the tip lens 191 and the wafer W. Retained.

As described above, according to the exposure apparatus 100 of the present embodiment, the reference mark plate FM has an average of the _four reference marks WM ₁ , WM ₂ , WM ₃ , WM ₄ for baseline measurement of the alignment system ALG. The position is formed so as to coincide with the position of the measurement pattern ST of the aerial image measuring device 125 that detects the alignment mark on the reticle R. For this reason, when the reference mark plate FM expands and contracts due to a temperature change or the like, the distance between the reference marks WM ₁ , WM ₂ , WM ₃ , WM ₄ , the reference marks WM ₁ , WM ₂ , WM ₃ , even if the distance between the WM ₄ and the measurement pattern ST changes, the average position of the reference marks WM ₁ , WM ₂ , WM ₃ , WM _{4 and} the position of the measurement pattern ST are always kept in agreement. . Therefore, in the baseline measurement using the reference marks WM ₁ , WM ₂ , WM ₃ , WM ₄ and the measurement pattern ST, generation of measurement errors is suppressed, and improvement in measurement accuracy is expected.

  Further, in this embodiment, regardless of the material of the fiducial mark plate FM, it is possible to always measure the baseline with high accuracy using the fiducial mark plate FM. Therefore, the fiducial mark plate can be manufactured from an arbitrary material. Is possible.

  Further, when the baseline measurement is completed, main controller 50 measures a wafer alignment mark of a predetermined sample shot among a plurality of shot areas on wafer W via alignment detection system ALG, Based on the measurement result and the previously measured baseline, step-and-scan exposure is performed by immersion exposure while moving wafer stage WST. Therefore, it is possible to improve the exposure accuracy.

  In the exposure apparatus 100 according to the present embodiment, the case where one measurement pattern ST is formed on the reference mark plate FM has been described. However, the present invention is not limited thereto, and there may be two or more measurement patterns ST. good. In short, it is only necessary that the average positions of the plurality of measurement patterns coincide with the average positions of the plurality of reference patterns.

Further, in the exposure apparatus 100 according to the present embodiment, the case where the four reference marks WM ₁ , WM ₂ , WM ₃ , and WM ₄ are formed on the reference mark plate FM has been described. Three reference marks may be formed on the plate so as to form vertices of an equilateral triangle, and five or more reference marks may be formed. In short, it is only necessary that the average position of the plurality of reference marks matches the position of the measurement pattern ST.

  In the exposure apparatus 100 according to the present embodiment, the slit STx and STy are scanned with respect to the aerial image RM ′ by moving the measurement pattern ST along the X-axis direction and the Y-axis direction. First, for example, by moving the measurement pattern ST in a direction that forms an angle of 45 degrees with respect to the X axis and the Y axis, the slits STx and STy simultaneously scan the aerial image RM ′ and transmit the slits STx and STy, respectively. The illumination light IL may be received by an individual light receiving element. In such a case, the position information of the aerial image RM ′ can be simultaneously measured in the X-axis direction and the Y-axis direction.

In addition, although the measurement time increases as the number of reference marks increases, for example, by measuring the position of the reference mark without stopping the measurement stage MST, a decrease in throughput can be avoided. In this case, when the reference marks WM ₁ , WM ₂ , WM ₃ , and WM _{4 are} measured by the alignment system ALG, the measurement blur is caused by flash illumination of the reference marks WM ₁ , WM ₂ , WM ₃ , and WM ₄ , respectively. Can be reduced.

Further, when the marks cannot be arranged so that the positions of the slits STx and STy and the average positions of the reference marks WM _{1 to} WM ₄ completely coincide with each other, the expansion / contraction of the reference mark plate FM is determined from the measurement results of the reference marks WM _{1 to} WM _4. And the rotation may be calculated, and the baseline measurement result may be corrected from the difference between the deformation amount and the average position.

  Further, the measurement time may be shortened by devising the movement path of the measurement stage MST in the aerial image measurement operation using the aerial image measuring device 125 and the reference mark detection operation.

In the above embodiment, all the four reference marks WM ₁ , WM ₂ , WM ₃ , and WM ₄ are detected. However, for example, only two reference marks, for example, the reference marks WM ₁ and WM ₃ are detected, If it can be determined from the detection result that the baseline is not fluctuating, the position of the detection center of the alignment system ALG when detecting the two reference marks without detecting the remaining two reference marks WM ₂ and WM _4. A baseline may be calculated based on an average of information. Of course, if it can be determined from the detection results of the two reference marks that the baseline is fluctuating, the remaining two reference marks may be detected and the baseline may be calculated in the same manner as in the above embodiment.

  In the above embodiment, the case where the exposure apparatus 100 includes the measurement stage MST separately from the wafer stage WST has been described. However, the present invention is not limited to this, and the measurement stage MST is not necessarily provided, and only the wafer stage WST is provided. The wafer stage WST may be provided with the reference mark plate FM, the light receiving system 110b, the illuminance monitor 122, the illumination unevenness measuring device 104, the aerial image measuring device 125, the wavefront aberration measuring device 127, and the like.

  In the above embodiment, the case where the present invention is applied to a step-and-scan type exposure apparatus has been described. However, the present invention is not limited to this, and the present invention is not limited to this. -It can be suitably applied to an exposure apparatus such as a stitch system.

  Further, the present invention is a multi-stage type exposure measure having a plurality of wafer stages as disclosed in JP-A-10-163099, JP-A-10-214783, JP-T 2000-505958, and the like. Can also be suitably applied.

  In the above embodiment, the case where the exposure apparatus 100 is a liquid immersion type exposure apparatus has been described, but the present invention is not limited to this.

  In the above embodiment, an exposure apparatus that locally fills the liquid between the projection optical system PL and the wafer W is employed. However, the present invention is disclosed in JP-A-6-124873 and JP-A-10-10. The present invention can also be applied to an immersion exposure apparatus that performs exposure in a state where the entire surface of a wafer to be exposed is immersed in a liquid as disclosed in US Pat. No. 303114, US Pat. No. 5,825,043 and the like. is there.

  In the above embodiment, a light transmissive mask in which a predetermined light shielding pattern (or phase pattern / dimming pattern) is formed on a light transmissive substrate is used. As disclosed in Japanese Patent No. 6,778,257, an electronic mask that forms a transmission pattern, a reflection pattern, or a light emission pattern based on electronic data of a pattern to be exposed may be used.

  The use of the exposure apparatus is not limited to the exposure apparatus for semiconductor manufacturing, but for example, an exposure apparatus for liquid crystal that transfers a liquid crystal display element pattern to a square glass plate, an organic EL, a thin film magnetic head, an image sensor (CCD, etc.), micromachines, DNA chips and the like can also be widely applied to exposure apparatuses. 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.

The light source of the exposure apparatus of each of the embodiments is not limited to the ArF excimer laser, but is a KrF excimer laser (output wavelength 248 nm), F ₂ laser (output wavelength 157 nm), Ar ₂ laser (output wavelength 126 nm), Kr ₂ laser. It is also possible to use a pulse laser light source (output wavelength: 146 nm) or an ultrahigh pressure mercury lamp that emits a bright line such as g-line (wavelength 436 nm) or i-line (wavelength 365 nm). A harmonic generator of a YAG laser or the like can also be used. In addition, a single-wavelength laser beam in the infrared region or visible region oscillated from a DFB semiconductor laser or fiber laser is amplified by, for example, a fiber amplifier doped with erbium (or both erbium and ytterbium), and a nonlinear optical crystal You may use the harmonic which wavelength-converted into ultraviolet light using. Further, the projection optical system may be not only a reduction system but also an equal magnification and an enlargement system.

  The semiconductor device was formed on the reticle by the step of designing the function / performance of the device, the step of manufacturing a reticle based on this design step, the step of manufacturing a wafer from a silicon material, and the exposure apparatus of the above embodiment. It is manufactured through a lithography step for transferring a pattern onto an object such as a wafer by liquid immersion exposure, a device assembly step (including a dicing process, a bonding process, and a packaging process), an inspection step, and the like. In this case, in the lithography step, the above-described immersion exposure method is executed using the exposure apparatus of the above-described embodiment, and a device pattern is formed on the object. Therefore, a highly integrated device can be manufactured with a high yield. .

  The mark member, the measuring method, and the measuring device of the present invention are suitable for measuring a baseline between sensors. The exposure apparatus of the present invention is suitable for exposing an object.

It is the schematic which shows the exposure apparatus which concerns on one Embodiment. It is a top view which shows a measurement table. It is a figure which shows the reference mark board vicinity in FIG. FIG. 2 is a block diagram showing a main configuration of a control system of the exposure apparatus in FIG. 1. FIG. 5A and FIG. 5B are diagrams for explaining aerial image measurement.

Explanation of symbols

50 ... main control unit, 100 ... exposure apparatus, 110b ... receiving system, ALG ... alignment system, ST ... measurement pattern, STx, STy ... _{slits, WM 1, WM 2, WM} 3, WM 4 ... reference marks, FM ... Reference mark plate, W ... wafer, R ... reticle, WST ... wafer stage, MST ... measurement stage.

Claims (6)

A mark member used for measuring a positional relationship between a plurality of sensors,
At least one first sensor mark used for measurement using the first sensor and at least three second sensor marks used for measurement using the second sensor are marks for the first sensor. A mark member including a pattern plate formed so that an average position of the second sensor mark and an average position of the mark for the second sensor coincide with each other.   Only one mark for the first sensor is provided on the pattern plate, and an average position obtained by averaging the measurement positions for each mark is provided around the mark for the first sensor. The mark member according to claim 1, wherein four marks for the second sensor are arranged so as to coincide with the position of the mark.   The mark member according to claim 1, wherein the mark for the first sensor is a measurement pattern used for aerial image measurement. The positional information of the said pattern image is measured by detecting a pattern image with the said 1st sensor via the said mark for at least 1 1st sensors of the mark member as described in any one of Claims 1-3. A first step of;
Mark detection for each second sensor by detecting each second sensor mark on the mark member using a second sensor that detects an alignment mark on an object on which the pattern image is generated. A second step of measuring positional information of the detection center of the second sensor at the time;
And a third step of calculating a baseline of the second sensor based on position information of the pattern image and position information of a detection center of the second sensor when the mark for each second sensor is detected. Method. A mark member according to any one of claims 1 to 3;
A first measurement system that measures the generation position information of the pattern image by detecting a pattern image on the object with the first sensor through the at least one first sensor mark of the mark member;
Each second sensor mark of the mark member is detected using a second sensor used for detecting an alignment mark on the object, whereby the second sensor mark is detected at the time of detection of the second sensor mark. A second measurement system for measuring position information of the detection center of the sensor;
A measurement system that calculates a baseline of the second sensor based on the generation position information of the pattern image and the position information of the detection center of the second sensor when the mark for each of the second sensors is detected. apparatus. An exposure apparatus that exposes an object with a pattern image,
A measuring device according to claim 5;
A movable body on which the object is placed and movable in a two-dimensional plane;
When detecting the position information of the alignment mark on the object placed on the moving body using the second sensor, and exposing the object with the pattern image based on the detection result and the baseline An exposure apparatus comprising: a control device that controls movement of the movable body.

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