JP2006032807A - Exposure device and device manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-precision pattern duplication method that is not subject to mask flexure in spite of a small clearance between the mask and projection optical system and eliminates exposure errors for defocusing. <P>SOLUTION: This exposure device comprises the position detection units (160a, 160b and 40) that radiate a detection light DL on a point of the mask R corresponding to the evaluation point in a view of the projection optical system PL from the projection optical system and the opposite side, and then detects positional information concerning the optical axis of the projection optical system PL at a detection point corresponding to the above evaluation point of the pattern surface of the mask according to the reflection from the mask of the detection light and a control unit 50 that controls at least the positions in the above optical axis direction of the mask R and object W according to the above positional information detected by the position detection units during pattern duplication. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exposure apparatus and a device manufacturing method, and more particularly to an exposure apparatus used when manufacturing a semiconductor element, a liquid crystal display element, and the like in a lithography process, and a device manufacturing method using the exposure apparatus.

  Conventionally, various exposure apparatuses are used in a lithography process for manufacturing a semiconductor element, a liquid crystal display element, or the like, but at present, it is formed on a mask or a reticle (hereinafter, collectively referred to as “reticle” as appropriate). An exposure apparatus, for example, step-and-repeat, that transfers a pattern onto an object such as a wafer or glass plate (hereinafter referred to as “wafer”) having a resist (photosensitive agent) coated on the surface via a projection optical system. In general, a reduction projection type exposure apparatus (so-called stepper) of the type and a scanning projection exposure apparatus (scanning stepper (also referred to as a scanner)) of a step-and-scan type are generally used.

  With higher integration of semiconductor elements and miniaturization of patterns, exposure apparatuses have been required to have higher resolution (high resolution). The resolution of the projection optical system provided in the projection exposure apparatus increases as the wavelength of exposure light to be used (hereinafter also referred to as “exposure wavelength”) decreases and as the numerical aperture (NA) of the projection optical system increases. For this reason, with the miniaturization of integrated circuits, the exposure wavelength used in the projection exposure apparatus has become shorter year by year, and the numerical aperture of the projection optical system has also increased. The mainstream exposure wavelength is 248 nm for a KrF excimer laser, but 193 nm for an ArF excimer laser having a shorter wavelength is also in practical use.

  In the projection exposure apparatus, the surface of the wafer is positioned within the range of the depth of focus (DOF) of the image plane of the projection optical system (the best image plane of the pattern) in order to prevent image blur due to defocus. It is necessary to perform exposure, and the depth of focus is important as well as the resolution. However, if the exposure wavelength is shortened and the numerical aperture NA is increased (increased NA) in order to increase the resolution, the depth of focus becomes narrower. Therefore, as a premise to position the wafer surface within the range of the focal depth of the image plane of the projection optical system, it is possible to accurately know the positional relationship between the best imaging plane of the pattern and the wafer surface in the optical axis direction of the projection optical system. Become very important.

  However, in recent years, an imaging error due to reticle deformation has gradually become ignorable. That is, the shape of the best imaging plane changes in accordance with the position and deflection of the pattern surface of the reticle, and when the pattern surface of the reticle is deformed, the direction perpendicular to the optical axis of the projection optical system of the pattern on the pattern surface The position of the pattern may also change, and such a lateral shift of the pattern also causes a distortion error.

  The above-mentioned reticle deformations are classified according to factors: (a) deflection due to its own weight, (b) deformation during polishing of the reticle glass substrate itself, and (c) contact between the two contact surfaces when holding the reticle on the reticle holder. Deformation that occurs according to the flatness, (d) deformation that accompanies thermal expansion of the reticle due to illumination light irradiation, and the like are conceivable. Since the state of deformation of such a reticle differs for each reticle and for each reticle holder of the exposure apparatus, in order to accurately measure the deformation amount of the reticle, the reticle is actually used as the reticle holder of the exposure apparatus. It is necessary to perform measurement while adsorbed and held.

  Therefore, in order to quickly measure the surface shape of the reticle, it may be possible to arrange a position sensor on the reticle stage side, similar to the oblique incidence type focal position detection system for detecting the focus position of the wafer (for example, , See Patent Document 1). In this case, since the pattern surface of the reticle is the lower surface, that is, the surface on the projection optical system side, the oblique incidence type position sensor needs to be arranged in the space between the reticle stage and the projection optical system or in the vicinity thereof. There is.

  However, particularly in a scanning exposure apparatus, the reticle stage needs to have sufficient rigidity so as not to be deformed even when subjected to stress during acceleration / deceleration. For example, the reticle stage has a sufficient thickness to the extent that it almost contacts the projection optical system. In many cases, the configuration is adopted. In addition, since the design of a high-performance projection optical system is easier when the space between the reticle and the projection optical system is narrower, the space between the projection optical system and the reticle is improved as the performance of the projection optical system becomes higher. Tend to be less. Therefore, in a recent projection exposure apparatus that employs a high-performance projection optical system, it is difficult as a real problem to dispose a reticle position sensor between the projection optical system and the reticle.

  As a technique for avoiding such inconvenience, a reticle position sensor may be arranged at a position away from the projection optical system, but in this case, in the pattern surface area irradiated with illumination light, Since it is difficult to measure the position in the optical axis direction at the detection point during scanning exposure, the surface position information of the pattern surface of the reticle that has been measured in advance is used, and the light of the reticle and wafer at the time of exposure is measured. Adjustment of the axial position is performed (see, for example, Patent Document 2). Therefore, there is an inconvenience that the surface position information of the irradiation area of the illumination light on the pattern surface during the scanning exposure cannot be measured in real time, which combines the deformation of the reticle and the vertical position change of the reticle.

JP-A-7-86154 JP-A-7-94388

  The present invention has been made under the circumstances described above. From the first viewpoint, the pattern formed on the mask (R) is transferred onto the object (W) via the projection optical system (PL). An exposure apparatus that irradiates at least one point on the mask corresponding to at least one evaluation point in the field of view of the projection optical system with detection light (DL) from the opposite side of the projection optical system, and detects the detection light (DL) Based on the reflected light of the light from the mask, position information relating to the optical axis direction of the projection optical system at a detection point corresponding to the at least one evaluation point on the pattern surface of the mask on which the pattern is formed is detected. A position detection device (160a, 160b, 40); the optical axis direction of the pattern image of the mask and the object based on the position information detected by the position detection device during the transfer of the pattern; It is an exposure apparatus comprising a; control device for controlling the relative positional relationship between the (50).

  According to this, at least one point on the mask corresponding to at least one evaluation point in the field of view of the projection optical system is irradiated with detection light from the side opposite to the projection optical system, and reflected light from the mask of the detection light is reflected on the mask. And a position detecting device for detecting position information related to the optical axis direction of the projection optical system at a detection point corresponding to the at least one evaluation point on the pattern surface of the mask. Even if the space between them is small, the position detection device can detect the position information regarding the optical axis direction of the projection optical system at the detection point without any trouble. In addition, even if there is little space between the mask and the projection optical system, this position detection device does not limit the degree of freedom of arrangement.

  The control device controls the position of at least one of the mask and the object (the object to which the pattern is transferred) in the optical axis direction based on the position information detected by the position detection device when the pattern is transferred. The Therefore, it is possible to obtain true surface position information of the exposure target area of the pattern surface, which combines the deformation of the mask and the position change in the optical axis direction of the mask. Based on this surface position information, at least the mask and the object can be obtained. By controlling the position in one optical axis direction, it is possible to transfer a highly accurate pattern without exposure failure due to defocusing.

  In this case, various configurations of the position detection device are conceivable. For example, the position detection device includes an irradiation system (160a) that irradiates the mask with the detection light from a direction inclined at a predetermined angle with respect to the optical axis of the projection optical system; and the pattern surface of the mask of the detection light And a light receiving system (160b) for receiving the first and second reflected light from each of the opposite surfaces; and based on light reception information of at least one of the first and second reflected light from the light receiving system. A calculation device (40) that performs a predetermined calculation and calculates position information regarding the optical axis direction at the at least one detection point on the pattern surface.

  In this case, the light receiving system includes light receiving elements (S1, S2) that receive the first and second reflected lights, respectively, and the calculation device is based on light reception information of the second reflected light. The positional information on the optical axis direction of the surface opposite to the pattern surface of the mask at the at least one detection point is calculated, and the detection point at the detection point is based on light reception information of the first and second reflected light. The thickness of the mask is calculated, and the position in the optical axis direction of the pattern surface at the at least one detection point can be calculated based on the calculated position information and information on the thickness of the mask. .

  In this case, the calculation device includes a distance between incident points of the first and second reflected lights on a light receiving surface of the light receiving element, an incident angle of the detection light with respect to the mask, and a refractive index of the mask. Based on the above, the thickness of the mask at the detection point can be calculated.

  In the exposure apparatus of the present invention, the position detection device irradiates a plurality of points on the mask individually corresponding to a plurality of evaluation points in the field of view of the projection optical system from the opposite side of the projection optical system. Then, based on the reflected light from the mask of each detection light, position information regarding the optical axis direction of the pattern surface at a plurality of detection points individually corresponding to the plurality of evaluation points is detected. Can do.

  In this case, the apparatus further includes a drive system that drives the mask and the object in synchronization with a predetermined scanning direction, and the plurality of detection points are arranged at least apart in the non-scanning direction orthogonal to the scanning direction. Can be.

  Further, in the lithography process, the pattern formed on the mask can be transferred onto the object through the projection optical system using the exposure apparatus of the present invention, so that the pattern can be formed on the object with high accuracy. Thus, a highly integrated microdevice can be manufactured with a high yield. Therefore, it can be said that this invention is a device manufacturing method using the exposure apparatus of this invention from another viewpoint.

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

  FIG. 1 schematically shows a configuration of an exposure apparatus 100 according to an embodiment of the present invention. The exposure apparatus 100 is a step-and-scan projection exposure apparatus (so-called scanner).

  The exposure apparatus 100 holds an illumination system 10 including a light source and an illumination optical system, and a reticle R as a mask illuminated by exposure illumination light (hereinafter abbreviated as “illumination light”) IL from the illumination system. It includes a reticle stage RST, a projection optical system PL that projects illumination light IL emitted from the reticle R onto a wafer W as an object, a wafer stage WST that holds the wafer W, and a control system thereof.

  The illumination system 10 includes an illumination uniformizing optical system including a light source, an optical integrator, etc., as disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-313250 (corresponding to US Patent Application Publication No. 2003/0025890). It includes a splitter, a relay lens, a variable ND filter, a reticle blind, etc. (all not shown). In this illumination system 10, a slit-shaped illumination area (hereinafter referred to as a “slit-shaped illumination area”) IAR that is defined by a reticle blind and extends in the X-axis direction on the reticle R is illuminated with illumination light IL with a substantially uniform illuminance. To do. As the illumination light IL, for example, ArF excimer laser light (wavelength 193 nm) is used. As the optical integrator, a fly-eye lens, a rod integrator (an internal reflection type integrator), a diffractive optical element, or the like can be used.

  The reticle R is loaded on the reticle stage RST and is sucked and held via a vacuum chuck (not shown). An opening 32 serving as a passage for the illumination light IL is formed in a lower portion of the reticle R of the reticle stage RST. Further, on the + Y side of the opening 32, a rectangular opening 34 that is substantially the same shape as the slit-shaped illumination area IAR described above when viewed from above and is elongated in the X-axis direction is formed. A reticle reference mark plate (hereinafter abbreviated as “reference plate”) RFM made of parallel flat glass is fixed to the upper surface of the reticle stage RST so as to cover the opening 34 (see FIG. 2). In the present embodiment, as the reference plate RFM, the design thickness is the same as that of the reticle R, and parallel flat glass made of the same material as the reticle R is used. The reference plate RFM and the reticle R are fixed on the reticle stage RST so that at least the lower surface thereof is substantially the same surface.

On the lower surface (bottom surface) of the reference plate RFM, evaluation marks for evaluating the imaging characteristics (distortion, magnification, focus, field curvature, etc.) of the projection optical system PL are formed. Specifically, on the bottom surface of the reference plate RFM, as shown in the bottom view of FIG. 3A, a plurality of pairs, for example, five pairs of evaluation marks FRM _1,1 , FRM _2,1 , FRM _{1, 2} , FRM ₂ , ₂ ,..., FRM ₁ , ₅ , FRM ₂ , ₅ are formed symmetrically with respect to the X axis passing through the center in the Y axis direction and are formed at predetermined intervals along the Y axis direction. . In FIG. 3 (A), cross marks are representative as FRM _1,1 , FRM _2,1 , FRM _1,2 , FRM _2,2 ,..., FRM _1,5 , FRM _2,5. However, the present invention is not limited to this, and each evaluation mark may be a two-dimensional mark. For example, the evaluation mark may be formed by two line and space patterns whose arrangement directions are orthogonal. Further, the arrangement of the evaluation marks is an example, and it is only necessary that the evaluation marks are distributed almost uniformly over the entire bottom surface of the reference plate RFM, particularly in the non-scanning direction (X-axis direction). In the present embodiment, the surface position of the reference plate RFM is adjusted so that the bottom surface (lower surface) of the reference plate RFM is flush with the designed pattern surface of the reticle R. In the present embodiment, the upper surface of the reference plate RFM is used as a reference when detecting surface position information (position information regarding the optical axis direction of the projection optical system PL) of the pattern surface of the reticle R described later.

  The reticle stage RST can be driven minutely in the XY plane perpendicular to the optical axis of the illumination system (matching the optical axis AX of the projection optical system PL described later) by the reticle stage drive unit 30 (rotation around the Z axis (θz Rotation), and at a scanning speed designated in a predetermined scanning direction (here, the Y-axis direction). In addition, reticle stage RST can be finely driven by reticle stage drive unit 30 in the Z-axis direction and in the tilt directions with respect to the XY plane (the θx direction that is the rotation direction around the X axis and the θy direction that is the rotation direction around the Y axis). It has become. The reticle stage drive unit 30 is configured by, for example, an electromagnetic motor having a coil for driving in the X-axis direction, a coil for driving in the Y-axis direction, and a coil for driving the Z-axis.

  The position of the reticle stage RST in the XY plane is set to, for example, 0.5 by a reticle laser interferometer (hereinafter referred to as “reticle interferometer”) 54R via a reflective surface formed (or provided) on the reticle stage RST. It is always detected with a resolution of about 1 nm. Here, actually, a reticle Y interferometer for detecting the position of reticle stage RST in the Y-axis direction and a reticle X interferometer for measuring the position of reticle stage RST in the X-axis direction are provided. These are typically shown as a reticle interferometer 54R. Further, at least one corner cube type mirror may be used instead of the reflecting surface extending in the X-axis direction used for detecting the position of the reticle stage RST in the scanning direction (Y-axis direction in the present embodiment). Here, 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, rotation in the rotation direction (θz direction) around the Z axis can also be measured.

  Position information of reticle stage RST from reticle interferometer 54R is supplied to main controller 50. Main controller 50 drives and controls reticle stage RST via reticle stage drive unit 30 based on the position information of reticle stage RST.

  Returning to FIG. 1, an illumination system 160 a that has a light source that is controlled to be turned on and off by the main controller 50 above the reticle stage RST (reticle R), and irradiates detection light toward the reticle R from an oblique direction. And a light receiving system 160b for receiving the reflected light of the detection light from the pattern surface of the reticle R and the like. An output signal from the light receiving system 160b is output to the controller 40 as a calculation device. In the present embodiment, the irradiation system 160a, the light receiving system 160b, and the controller 40 constitute a position detection device that detects position information regarding the optical axis AX direction of the projection optical system at a plurality of detection points described later on the pattern surface of the reticle R. ing.

The irradiation system 160a includes, for example, a light source (not shown) such as a light emitting diode that irradiates red light belonging to a wavelength range of about 600 to 800 nm as detection light, an aperture plate in which a pinhole or slit-shaped aperture is formed, and irradiation The detection light (pinhole image or image light beam of a slit-shaped aperture image) is given to a plurality of points in an area corresponding to the above-described illumination area IAR on the upper surface of the reticle R. Irradiate at an incident angle of. Here, in actuality, as shown in FIG. 2, the irradiation system 160a includes a plurality (in the non-scanning direction (X-axis direction)) arranged at predetermined intervals in the illumination area IAR on each of the upper surface and the lower surface of the reticle R. Here, detection light DL ₁ , DL ₂ , and DL ₃ are respectively irradiated to _three detection points. In the following description, the detection lights DL ₁ , DL ₂ , DL ₃ are collectively referred to as detection light DL as appropriate.

In this case, as the irradiation system 160a, a configuration having three each of the light source, the slit plate, and the irradiation objective lens can be adopted, or light from a single light source is divided into three by the optical system, and each divided light beam is divided. Can be adopted as the detection light DL ₁ , DL ₂ , DL ₃ .

  As schematically shown in FIG. 4, the light receiving system 160b reflects reflected light DL′1 and DL′2 from the upper surface and the lower surface (pattern surface) of the reticle R of the detection light DL emitted from the irradiation system 160a. Includes a light receiving optical system 70 disposed on the optical path of the first and second light detectors S1 and S2 that receive the reflected lights DL′1 and DL′2 via the light receiving optical system 70, respectively. It is configured.

  The light receiving optical system 70 includes a light receiving objective lens, a parallel plate glass (both not shown), and the like. In this case, by changing the inclination of the parallel flat glass with respect to the reflected light beams DL′1 and DL′2, the reflected lights DL′1 and DL′2 incident on the first and second photodetectors S1 and S2 are changed. The position on the light receiving surface can be shifted in the directions of arrows A and A ′ in FIG. In this embodiment, the inclination angle of the parallel flat glass is controlled by the main controller 50 via a drive system (not shown), and the calibration of the first and second photodetectors S1 and S2 (reset of the origin) is performed. ) Is to be performed.

  As the first and second photodetectors S1 and S2, a light receiving element capable of detecting a light receiving position such as a line sensor, a one-dimensional or two-dimensional CCD is used. In this case, the first and second photodetectors S1 and S2 are fixed to the same fixing member so that the positional relationship does not fluctuate.

  As shown in FIG. 4, the first photodetector S1 receives the reflected light DL′1 on the upper surface of the reticle R of the detection light DL irradiated from the irradiation system 160a, and sends the detection signal to the controller described above. Output to 40. The second photodetector S 2 receives the reflected light DL ′ 2 of the detection light DL reflected by the lower surface (pattern surface) of the reticle R, and outputs the detection signal to the controller 40.

  The controller 40 relates to the Z-axis direction of the surface opposite to the pattern surface of the reticle R at each of the three detection points based on the output of the first photodetector S1 (light reception information of the reflected light DL′1). The position information is calculated, and the thickness of the reticle R at each detection point is calculated based on the outputs of the first and second photodetectors S1 and S2 (light reception information of the reflected lights DL′1 and DL′2). Then, the position of the pattern surface at each detection point in the optical axis direction (Z-axis direction) is calculated based on the previously calculated position information and information on the thickness of the reticle R, and information on the calculation result is used as the main controller 50. Output to. The calculation method by the controller 40 will be described in detail later.

  Returning to FIG. 1, the projection optical system PL uses, for example, a double telecentric reduction system. The projection magnification of the projection optical system PL is, for example, 1/4, 1/5, or 1/6. Therefore, as described above, when the slit-shaped illumination area IAR on the reticle R is illuminated by the illumination light IL, a reduced image of the circuit pattern in the illumination area IAR is illuminated via the projection optical system PL. Is formed in an irradiation area (hereinafter referred to as an “exposure area”) IA of the illumination light IL on the wafer W which is conjugate with the wafer W.

As the projection optical system PL, a refraction system including only a plurality of, for example, about 10 to 20 refractive optical elements (lens elements) 13 is used. Of a plurality of lens elements 13 that constitute the projection optical system PL, a plurality of the object plane side (reticle R side) (here, four in order to simplify the description) lens elements 13 _1, Reference numerals 13 ₂ , 13 ₃ , and 13 ₄ are movable lenses that can be driven from the outside by the imaging characteristic correction controller 48. The imaging characteristic correction controller 48 shifts each of the lens elements 13 _{1 to} 13 ₄ in the Z-axis direction, which is the optical axis direction of the projection optical system PL, by independently adjusting the voltage applied to a drive element (not shown). The driving and tilting directions with respect to the XY plane (namely, the rotation direction around the X axis (θx direction) and the rotation direction around the Y axis (θy direction) are possible (tiltable).

In addition to the lens elements 13 _{1 to} 13 ₄ , the aberration of the lens element disposed in the vicinity of the pupil plane of the projection optical system PL or in the image plane side, or the projection optical system PL, particularly its non-rotationally symmetric component, is corrected. An aberration correction plate (optical plate) or the like may be driven. Furthermore, the degrees of freedom (movable directions) of these drivable optical elements are not limited to three, but may be one, two, or four or more.

  On wafer stage WST, wafer W is fixed by vacuum suction via wafer holder 25. Wafer stage WST is disposed below projection optical system PL and can be driven in the XY plane (including the θz direction) by wafer stage drive unit 56 including a linear motor, a planar motor, a voice coil motor (VCM), and the like. In addition, it can be finely driven in the Z-axis direction and the tilt directions with respect to the XY plane (the rotation direction around the X axis (θx direction) and the rotation direction around the Y axis (θy direction)).

  The position of wafer stage WST in the XY plane (including rotation around the Z axis (θz rotation)) is transferred to a wafer laser interferometer (hereinafter referred to as “wafer interferometer”) via moving mirror 52W fixed to wafer stage WST. 54W, for example, is always detected with a resolution of about 0.5 to 1 nm.

  In practice, the moving mirror is provided with an X moving mirror having a reflecting surface orthogonal to the X axis and a Y moving mirror having a reflecting surface orthogonal to the Y axis. An X-laser interferometer for measuring the directional position and a Y-laser interferometer for measuring the Y-direction position are provided. In FIG. 1, these are representatively shown as a movable mirror 52W and a wafer interferometer 54W. For example, the end surface of the wafer table 18 may be mirror-finished to form a reflecting surface (corresponding to the reflecting surface of the movable mirror 52W). The X laser interferometer and the Y laser interferometer are multi-axis interferometers having a plurality of measurement axes, and in addition to the X and Y positions of the wafer stage WST, rotation (yawing (θz rotation that is rotation around the Z axis)) , Pitching (θx rotation that is rotation around the X axis), and rolling (θy rotation that is rotation around the Y axis)) can also be measured. Therefore, in the following description, it is assumed that the position of wafer stage WST in the X, Y, θz, θy, and θx directions of five degrees of freedom is measured by wafer interferometer 54W. Further, the multi-axis interferometer irradiates the laser beam on the reflecting surface installed on the gantry (not shown) on which the projection optical system PL is placed via the reflecting surface installed on the wafer stage WST with an inclination of 45 °. The relative position information regarding the optical axis direction (Z-axis direction) of the projection optical system PL may be detected.

  Position information (or speed information) of wafer stage WST detected by wafer interferometer 54W is supplied to main controller 50. Main controller 50 controls the position of wafer stage WST via wafer stage drive unit 56 based on the position information (or speed information) of wafer stage WST.

  Further, in the vicinity of wafer W on the upper surface of wafer stage WST, fiducial mark plate FM is fixed in a state where the surface thereof is the same height as the surface of wafer W. A light-shielding film is formed on the surface of the reference mark plate FM, and the slit-shaped opening pattern 22x extending in the Y-axis direction and the X-axis direction extend in the light-shielding film as shown in FIG. A slit-shaped opening pattern 22y is formed. These slit-like opening patterns (hereinafter abbreviated as “slits”) are aerial image measurement slits for measuring the imaging characteristics (distortion, magnification, best focus, field curvature, etc.) of the projection optical system PL. It is.

  Inside the wafer stage WST below the slit 22x of the reference mark plate FM, as shown in FIG. 3C, there are a lens 29a and a photoelectric detector 29b composed of, for example, a photomultiplier tube (PMT). Is provided. In this case, the illumination light IL that has passed through the slit 22x is received by the photoelectric detector 29b through the lens 29a inside the wafer stage WST. Similarly, photoelectric detectors that receive illumination light IL that has passed through slits 22y are also fixed below slits 22y inside wafer stage WST, and detection signals from these photoelectric detectors are sent to main controller 50 in FIG. Have been supplied. Note that at least the photoelectric detector 29b may be arranged outside the wafer stage WST so that the illumination light IL transmitted through the reference mark plate FM is guided to the photoelectric detector 29b.

In the present embodiment, when detecting, for example, the X coordinate (or Y coordinate) of the projection image of the evaluation mark FRM _1,1 on the reference plate RFM shown in FIG. Wafer stage WST is moved in the X-axis direction (or Y-axis direction) via wafer stage drive unit 56 so that slit 22x (or slit 22y) of reference mark plate FM crosses the projected image of mark FRM _1,1 for evaluation. During the scanning, the detection signal of the photoelectric detector 29b is sampled in correspondence with the X coordinate (or Y coordinate) of the wafer stage WST. Thereafter, main controller 50 detects, for example, the X coordinate (or Y coordinate) of evaluation mark FRM _1,1 as the coordinate of the midpoint of the slice point when the detection signal is binarized with a predetermined threshold. .

Further, in order to detect the position (best focus position) of the image plane of the projection image of evaluation mark FRM _1,1 , main controller 50 determines the position of wafer stage WST (reference mark plate FM) in the Z-axis direction. (Z position) is changed stepwise at a predetermined pitch, and the contrast of the detection signal obtained when the projection image is scanned by the slit 22x at each Z position is detected, and the reference mark plate FM when the contrast becomes the highest Is detected as the best focus position of the projected image. By detecting the best focus position for evaluation marks of various image heights, it is possible to obtain the image plane by calculating the least square approximation surface of the best focus position of each evaluation mark. It is.

  Further, in the exposure apparatus 100 of the present embodiment, as shown in FIG. 1, an oblique incidence type multi-point focal position detection system that measures the position of the wafer W in the optical axis AX direction, which includes an irradiation system 60a and a light receiving system 60b. (60a, 60b) are provided. The irradiation system 60a has a light source whose ON / OFF is controlled by the main control device 50, and forms a large number of pinholes or slit images toward the image plane of the projection optical system PL. The image light beam is applied to the surface of the wafer W from an oblique direction with respect to the optical axis AX. The light receiving system 60b receives a reflected light beam generated by reflecting the imaged light beam on the surface of the wafer W, and detects a defocus signal (defocus signal) for detecting a defocus to the main controller 50. For example, an S curve signal is transmitted. The detailed configuration of the multipoint focal position detection system (60a, 60b) and the same multipoint focal position detection system is disclosed in, for example, Japanese Patent Laid-Open No. 6-283403 (corresponding US Pat. No. 5,448,332). ) Etc., and detailed description thereof is omitted.

  Further, the exposure apparatus 100 is an off-axis method used for measuring the positions of the alignment marks on the wafer W held on the wafer stage WST and the reference marks formed on the reference mark plate FM. An alignment system ALG is provided. As this alignment system ALG, for example, the target mark is irradiated with a broadband detection light beam that does not sensitize the resist on the wafer, and the target mark image formed on the light receiving surface by the reflected light from the target mark and an index (not shown) An image processing type FIA (Field Image Alignment) type sensor that captures the image of the image using an image sensor (CCD or the like) and outputs the imaged signals is used. In addition to the FIA system, the target mark is irradiated with coherent detection light to detect scattered light or diffracted light generated from the target mark, or two diffracted lights (for example, of the same order) generated from the target mark. Of course, it is possible to use an alignment sensor that detects the interference by interfering with each other singly or in an appropriate combination.

  The control system is mainly configured by the main controller 50 in FIG. The main controller 50 includes a so-called workstation (or microcomputer) including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. In addition to performing the above control operation, the entire apparatus is controlled in an integrated manner.

  The main controller 50 monitors the measurement values of the reticle interferometer 54R and the wafer interferometer 54W, for example, so that the scanning exposure operation can be performed accurately, and the reticle controller 50 and the wafer stage driver 56 respectively. Controls synchronous scanning with reticle stage RST (reticle R) and wafer stage WST (wafer W). In other words, in this embodiment, the reticle stage driving unit 30, the wafer stage driving unit 56, and the main controller 50 constitute a driving system that drives the reticle R and the wafer W in synchronization with a predetermined scanning direction. Main controller 50 also controls stepping of wafer stage WST (wafer W).

  Next, the principle of calculating the position of the lower surface (pattern surface) of the reticle R in the Z-axis direction (optical axis AX direction) by the controller 40 will be described with reference to FIG. FIG. 4 shows a case where the magnification D of the light receiving optical system 70 is 1 as an example.

  As a premise, the photodetectors S1 and S2 are calibrated as will be described later, and the controller 40 has a reference point (hereinafter referred to as a “first reference point”) on the light receiving surface of the photodetector S1. The coordinates of a reference point on the light receiving surface of the second photodetector S2 (hereinafter referred to as “second reference point”) are stored in the memory.

  When measuring position information in the Z-axis direction (optical axis AX direction) of the lower surface (pattern surface) of the reticle R, as shown in FIG. 4, the detection light DL is irradiated from the irradiation system 160a onto the reticle R at an incident angle α. Is done. A part of the detection light DL is reflected on the upper surface of the reticle R at a reflection angle α, and the rest is refracted on the upper surface of the reticle R, and enters the inside of the glass material forming the reticle R at the emission angle β. Incident. The light incident on the inside of the glass material enters the pattern surface at an incident angle β, is reflected by the pattern surface at the reflection angle β, and the reflected light DL′2 is refracted again by the upper surface of the reticle R, and then receives light. The light is received by the second photodetector S2 via the system 70. On the other hand, the reflected light DL ′ 1 reflected by the upper surface of the reticle R is received by the first photodetector S 1 via the light receiving optical system 70.

  Further, from the geometric relationship of FIG. 4, the distance δ of the reflected light DL′1 and the reflected light DL′2 after passing through the light receiving optical system 70 (that is, on the light receiving surface of the photodetector S1 of the reflected light DL′1). The relationship between the incident position of the reflected light DL′2 and the incident position of the reflected light DL′2 on the light receiving surface of the photodetector S2) can be expressed by the following equation (1), where t is the thickness of the reticle R.

δ = 2t · tanβ · cosα (1)
From the above equation (1),
t = δ / (2 tan β · cos α) (2)
Is obtained.

  When a light receiving optical system having a projection magnification D is used, the distance δ and the thickness t can be expressed by the following expressions (3) and (4), respectively.

δ = 2D · t · tanβ · cosα (3)
t = δ / (2D · tanβ · cosα) (4)
The incident angle α is a preset value and is known. The exit angle β depends on the incident angle α and the refractive index n of the material forming the reticle R, and is a value that can be derived from the relationship n = sin α / sin β, and is a constant. The projection magnification D is also a known value.

  Therefore, it can be replaced with a coefficient of 1 / (2D · tan β · cos α) = K. As a result, the thickness t of the reticle R can be expressed by the following equation (5).

t = Kδ (5)
The positional relationship between the first reference point on the light receiving surface of the photodetector S1 and the second reference point on the light receiving surface of the photodetector S2 is known, and the photodetector S1 of the reflected light DL′1. Is obtained as coordinates with the first reference point as the origin from the output of the light detector S1, and the incident position of the reflected light DL′2 on the light receiving surface of the light detector S2 is a light beam. From the output of the detector S2, it is obtained as coordinates with the second reference point as the origin. As a result, the distance δ is obtained based on the output of the photodetector S1 and the output of the photodetector S2.

  Therefore, the controller 40 calculates the distance δ based on the output of the photodetector S1 and the output of the photodetector S2, and calculates the thickness of the reticle R based on the calculated δ and Equation (5). To do.

  Further, the controller 40 calculates the Z position information of the upper surface of the reticle R, that is, the Z position Zr of the upper surface of the reticle R based on the Z position of the upper surface of the reference plate RFM, based on the output of the photodetector S1.

  Then, the controller 40 calculates the Z position information Zp of the pattern surface of the reticle R on the basis of the Z position of the upper surface of the reference plate RFM based on the following equation (6).

Zp = Zr-t (6)
Here, Zr is positive when the upper surface of the reticle R is on the + Z side with respect to the upper surface of the reference plate RFM, and is negative when the upper surface of the reticle R is on the −Z side with respect to the upper surface of the reference plate RFM. . Normally, the reticle R bends so that its central portion protrudes downward due to its own weight, so that Zr is normally considered to be a negative value.

  Next, the calibration operation of the first and second photodetectors S1 and S2 constituting the above-described position detection device, the adjustment operation of the imaging characteristics of the projection optical system PL performed together with this, and the like will be described.

Main controller 50 drives reticle stage RST to move reference plate RFM to slit-shaped illumination area IAR, and irradiates reference plate RFM with detection light DL from irradiation system 160a. As a result, the detection light beams DL ₁ , DL ₂ , DL ₃ are irradiated to the individual measurement points in the center in the X-axis direction on the center line in the Y-axis direction on the upper surface of the reference plate RFM, and the upper surface of each reference plate RFM Reflected lights DL′1 and DL′2 on the lower surface are received by the respective photodetectors constituting the light receiving system 160b. At this time, based on an instruction from the main controller 50, the controller 40 sets each incident position of the reflected light DL′1 on the light receiving surface of each photodetector S1 to coincide with the origin on the light receiving surface. Each photodetector S1 is calibrated by adjusting the angle of the parallel flat glass in the light receiving optical system 70. In the controller 40, the coordinates of the origin of each photodetector S1 at this time are stored as the coordinates of the first reference point on the light receiving surface of the photodetector S1.

  Further, in the controller 40, immediately after the angle adjustment of each parallel plate glass, the reflected light DL′2 on the light receiving surface of the second photodetector S2 is based on the output of the second photodetector S2. Are stored as the coordinates of the second reference point on the light receiving surface of the second photodetector S2. Thereby, the calibration operation of the first and second photodetectors S1 and S2 constituting the position detection device is completed.

In parallel with the calibration operations of the first and second photodetectors S1 and S2, the main controller 50 illuminates the reference plate RFM with the illumination light IL. As a result, the images of evaluation marks FRM _{1,1 to} FRM _{2,5 on} the reference plate RFM shown in FIG. 3A are projected onto the wafer stage WST side via the projection optical system PL. Therefore, main controller 50 scans a predetermined plurality (three or more) of evaluation mark images with slits 22x (see FIG. 3B) while changing the Z position of reference mark plate FM as described above. Then, the best focus position of each image is obtained from the contrast of the detection signal, and the optimum image plane (matching plane) is determined from these best focus positions by, for example, the least square method.

  Further, when changing the Z position of the reference mark plate FM in such a manner, the main controller 50 uses the multi-point focal position detection system (60a, 60b) at the measurement points near the images of the plurality of evaluation marks. Surface position information (Z position information) is detected, and surface position information at the best focus position of the plurality of images is obtained. Further, the main controller 50 determines the surface position information of each measurement point of the multipoint focal position detection system (60a, 60b) on the optimum image plane (the preset multipoint focal position detection system (60a, 60b)). The offset amount with respect to the detection origin) is supplied to the wafer stage drive unit 56.

  Instead of supplying the offset amount, for example, the incident angle of the detection light from the irradiation system 60a or the position of the slit image re-imaged in the light receiving system 60b may be shifted so as to cancel the offset. Good.

  Thereafter, in a state where the surface of the wafer W is in the exposure region at the time of exposure, the wafer stage drive unit 56 calculates the offset from the defocus amount obtained from the focus signal supplied from the multipoint focus position detection system (60a, 60b). The Z position and tilt angle of wafer stage WST are controlled so that the subtracted values are 0, respectively. As a result, the surface of the wafer W is accurately aligned with a plane that approximates the image plane by the projection optical system PL on the lower surface of the reference plate RFM, that is, an optimal image plane (matching plane).

Next, the main controller 50 corrects the curvature of field via the imaging characteristic correction controller 48 of FIG. However, here, it is assumed that the curvature of field can be changed to some extent by driving the movable lenses 13 _{1 to} 13 ₄ . At this time, since the average focus position also changes, the main controller 50 calculates the amount of change ΔZ ′ of the remaining focus position, and the target value of the Z position on the surface of the wafer W with respect to the wafer stage drive unit 56. Is changed by −ΔZ ′. As a result, the curvature of field and defocus due to the bending of the pattern surface of the reticle R are corrected, and the surface of the wafer W is adjusted to the actual image surface with respect to the pattern surface of the reticle R with high accuracy.

  When the distortion changes due to the deformation of the pattern surface of the reticle R, the distortion is also corrected through the imaging characteristic correction controller 48.

  In exposure apparatus 100 configured as described above, reticle alignment and alignment system ALG base line measurement, wafer alignment (such as EGA), and step-and-scan methods are performed in the same procedure as a normal scanning stepper. An exposure operation is performed.

  In the exposure apparatus 100 of the present embodiment, during the above-described step-and-scan exposure operation, in particular, during scanning exposure, the irradiation system 160a and the light-receiving system 160b constituting the position detection apparatus are positioned in the slit-shaped illumination area IAR. The Z position information of the pattern surface of the reticle R to be detected is detected at each of the three detection points described above, and the surface position information at each detection point is calculated in real time by the controller 40 and supplied to the main controller 50. During scanning exposure, detection signals from the multipoint focal position detection system (60a, 60b) are also supplied to the main controller 50.

  Therefore, main controller 50 calculates in real time the displacement and tilt amount (mainly the amount of rotation about the Y axis) from the reference plane of the reticle stage based on the surface position information from controller 40, and these displacements. Further, the Z position and tilt of the reticle stage RST are controlled via the reticle stage drive unit 30 so that the tilt amount becomes zero. At the same time, main controller 50 calculates an approximate plane of the surface of the exposure area IA on wafer W based on the detection signal from the multipoint focal position detection system (60a, 60b). By finely driving the wafer stage WST in the Z-axis direction, the θx direction, and the θy direction via the wafer stage drive unit 56 so as to be within the range of the focal depth of the projection optical system PL, Perform leveling control.

  As described above, the exposure apparatus 100 of the present embodiment has three points on the reticle R corresponding to the three evaluation points in the field of view (particularly the exposure area IA) of the projection optical system PL on the side opposite to the projection optical system PL. The projection optical system PL at the detection point corresponding to the three evaluation points on the pattern surface of the reticle R is irradiated with the detection light DL from (on the upper side of the reticle R) and based on the reflected light from the reticle R of the detection light DL. Are provided with position detecting devices (160a, 160b, 40) for detecting position information relating to the optical axis direction. For this reason, even if there is little space between the reticle R and the projection optical system PL, position information (surfaces) regarding the optical axis direction of the projection optical system PL at the detection point without any trouble by this position detection device (160a, 160b, 40). Position information) is detected. Further, even if there is little space between the reticle R and the projection optical system PL, the position detection devices (160a, 160b, 40) do not limit the degree of freedom of arrangement.

  Further, according to the exposure apparatus 100 of the present embodiment, the surface position at each detection point detected by the position detection apparatus (160a, 160b, 40) by the main controller 50 during pattern transfer (scan exposure). Based on the information, the Z position and tilt (mainly tilt in the non-scanning direction) of the reticle R are controlled. As described above, according to the exposure apparatus 100, the true surface position information of the exposure target area of the pattern surface can be obtained by combining the deformation of the reticle R and the position change of the reticle R in the optical axis direction. By controlling the Z position and tilt of the reticle R (mainly tilt in the non-scanning direction) based on the position information, it is possible to prevent the position and tilt of the pattern surface from changing in the Z-axis direction. In particular, in the present embodiment, since the Z position and tilt of the reticle R can be measured during scanning exposure, the reticle stage RST can be measured regardless of the change in the scanning speed and acceleration of the reticle stage RST. Even if the posture of the stage RST changes, the true surface position information of the exposure target area of the pattern surface can be obtained accurately and without any particular trouble. Further, the main controller 50 performs the focus / leveling control of the wafer W described above in parallel with the Z position and tilt of the reticle R, so that the reticle R onto the wafer with high accuracy without exposure failure due to defocusing. The pattern can be transferred.

  In the above embodiment, the thickness of the reticle R is measured using the position detection devices (160a, 160b, 40). However, the present invention is not limited to this, and the thickness of the reticle R is not limited thereto. The thickness or thickness distribution may be measured, and the measurement result may be stored in a memory together with the reticle number and the like for each reticle. In this case, the Z position of the pattern surface of the reticle R is calculated for each detection point based on the Z position information of the pattern surface of the reticle R measured by the position detection device and the thickness information of the known reticle. It ’s fine.

  Further, in the above embodiment, the Y position between the detection point on the reticle upper surface and the detection point on the pattern surface is slightly different from the relationship of calculating the surface position information on the pattern surface of the reticle R using the position detection device of the oblique incidence method. It is shifted. However, since the reticle is made of a glass plate with good flatness, the influence of the deviation of the Y position between the detection points on the thickness measurement is negligibly small. The measured thickness is the pattern of the reticle. There is no problem even if it is regarded as the thickness of the reticle at the position of the detection point on the surface.

  However, in order to eliminate such an error, for example, the reticle R is scanned once in advance, the output data of the photodetectors S1 and S2 is sampled at a predetermined sampling interval, and the sampled data is obtained. It is also possible to reconstruct the output data sets of the photodetectors S1 and S2 at the same Y position and calculate the exact thickness distribution of the reticle R from the reconstructed data.

  Further, in the above embodiment, three detection points of the position detection device are arranged in the slit-like illumination area IAR in the non-scanning direction, and based on the surface position information of the pattern surface at each detection point, the reticle R Although the Z position and the θy rotation are controlled, the surface position information at the time s at each detection point and the surface position information at the time s−Δs at each detection point acquired at each sampling interval Δs during the scan. Based on this, the θx rotation of reticle stage RST (reticle R) may also be controlled.

  Alternatively, the detection points of the position detection device may be set in the slit-shaped illumination area IAR at predetermined intervals in the XY two-dimensional direction. Alternatively, for example, only the detection point on the optical axis of the projection optical system PL may be provided, and only the Z position of the reticle R may be controlled. Further, in the above-described position detection device, at least one detection point is set outside the illumination area IAR in the ± Y direction instead of or in combination with at least one detection point in the illumination area IAR. Also good.

  Note that instead of controlling the Z position and tilt of the reticle stage RST based on the positional information on the pattern surface of the reticle R obtained from the position detection device (160a, 160b, 40) during scanning exposure, or in combination therewith, Wafer stage WST may be finely moved in the Z-axis direction, θx and θy directions. Further, based on the detection result of the multipoint focal position detection system (60a, 60b), reticle stage RST may be driven instead of or in combination with wafer stage WST. That is, the pattern image of the reticle R (imaging plane of the projection optical system PL) and the surface of the wafer W in the exposure area IA according to the displacement and inclination amounts of the pattern surface of the reticle R and the surface of the wafer W in the Z-axis direction, respectively. In the detection results of both the position detection devices (160a, 160b, 40) and the multipoint focus position detection system (60a, 60b) so that the relative deviation is within the range of the focal depth of the projection optical system PL. Based on this, at least one of reticle stage RST and wafer stage WST may be driven. Further, instead of driving at least one of reticle stage RST and wafer stage WST, or in combination with it, for example, by moving at least one optical element of projection optical system PL, the optical characteristics thereof are adjusted, and the exposure region Within the IA, the image plane of the projection optical system PL and the surface of the wafer W may be matched within the range of the depth of focus.

  Moreover, the structure of the position detection apparatus (160a, 160b, 40) demonstrated by the said embodiment is an example, and this invention is not limited to this. For example, the photodetector constituting the light receiving system 160b can of course be constituted by a single photodetector (light receiving element) having a large area light receiving surface such as a CCD sensor. In the above embodiment, the evaluation point in the exposure area IA corresponding to the detection point of the position detection device may be substantially coincident with the detection point (detection light irradiation position) of the multipoint focal position detection system.

  In the exposure apparatus of the above embodiment, the magnification of the projection optical system may be not only a reduction system but also an equal magnification and an enlargement system, and the projection optical system PL is not only a refraction system but also any of a reflection system and a catadioptric system. However, the projected image may be either an inverted image or an erect image.

In the above embodiment, ArF excimer laser light is used as the illumination light IL. However, the present invention is not limited to this. Light having a wavelength of 170 nm or less, for example, F ₂ laser light (wavelength 157 nm), Kr ₂ laser light ( Other vacuum ultraviolet light such as a wavelength of 146 nm) may be used. Further, a g-line, i-line, KrF excimer laser, or the like may be used.

  Further, for example, not only laser light output from each of the above light sources as vacuum ultraviolet light, but also single wavelength laser light in the infrared region or visible region oscillated from a DFB semiconductor laser or fiber laser, for example, erbium (Er) A harmonic that is amplified by a fiber amplifier doped with erbium and ytterbium (Yb) and wavelength-converted into ultraviolet light using a nonlinear optical crystal may be used.

  An immersion type exposure apparatus or a step-and-stitch method disclosed in, for example, International Publication WO99 / 49504, where a liquid (for example, pure water) is filled between the projection optical system PL and the wafer. The present invention can also be suitably applied to such an exposure apparatus or a proximity type exposure apparatus. That is, in a reticle that can irradiate detection light from the back side of the reticle to both the pattern surface and the back side regardless of the type of exposure apparatus, exposure wavelength, reticle material, and the like, and an exposure apparatus that uses the reticle. If present, the present invention can be suitably applied.

  An illumination optical system and projection optical system composed of a plurality of lenses are incorporated into the exposure apparatus body for optical adjustment, and a reticle stage and wafer stage made up of a number of mechanical parts are attached to the exposure apparatus body to provide wiring and piping. , And further performing general adjustment (electrical adjustment, operation check, etc.), the exposure apparatus of each of the above embodiments can be manufactured. 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, and an exposure apparatus that is used for manufacturing an imaging device (CCD or the like), micromachine, organic EL, DNA chip, and the like. 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, meteorite, 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.

<Device manufacturing method>
FIG. 5 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. 5, first, in step 201 (design step), device function / performance design (for example, circuit design of a semiconductor device) is performed, and pattern design for realizing the function is performed. Subsequently, in step 202 (mask manufacturing step), a mask on which the designed circuit pattern is formed is manufactured. On the other hand, in step 203 (wafer manufacturing step), a wafer is manufactured using a material such as silicon.

  Next, in step 204 (wafer processing step), using the mask and wafer prepared in steps 201 to 203, an actual circuit or the like is formed on the wafer by lithography or the like as will be described later. Next, in step 205 (device assembly step), device assembly is performed using the wafer processed in step 204. Step 205 includes processes such as a dicing process, a bonding process, and a packaging process (chip encapsulation) as necessary.

  Finally, in step 206 (inspection step), inspections such as an operation confirmation test and durability test of the device created in step 205 are performed. After these steps, the device is completed and shipped.

  FIG. 6 shows a detailed flow example of step 204 in the semiconductor device. In FIG. 6, in step 211 (oxidation step), the surface of the wafer is oxidized. In step 212 (CVD step), an insulating film is formed on the wafer surface. In step 213 (electrode formation step), an electrode is formed on the wafer by vapor deposition. In step 214 (ion implantation step), ions are implanted into the wafer. Each of the above-described steps 211 to 214 constitutes a pre-processing process at each stage of the wafer processing, and is selected and executed according to a necessary process at 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 215 (resist formation step), a photosensitive agent is applied to the wafer. Subsequently, in step 216 (exposure step), the circuit pattern of the mask is transferred to the wafer by the exposure apparatus and the exposure method described above. Next, in step 217 (development step), the exposed wafer is developed, and in step 218 (etching step), the exposed members other than the portion where the resist remains are removed by etching. In step 219 (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.

  If the device manufacturing method of this embodiment described above is used, the exposure apparatus of the above embodiment is used in the exposure step (step 216), so that the pattern of the reticle can be transferred onto the wafer with high accuracy, and as a result. In addition, the productivity (including yield) of highly integrated devices can be improved.

  The exposure apparatus of the present invention is suitable for transferring a mask pattern onto an object in a lithography process. The device manufacturing method of the present invention is suitable for manufacturing micro devices.

1 is a view schematically showing a partial cross section of a configuration of an exposure apparatus according to an embodiment of the present invention. It is a perspective view which shows the reticle stage in FIG. 3A is a bottom view showing the reference plate RFM of FIG. 1, FIG. 3B is a plan view showing the reference mark plate FM of FIG. 1, and FIG. 3C is the inside of the wafer stage below the reference mark plate FM. It is a figure which shows the detection system. It is a figure for demonstrating the principle of calculation of the position of the Z-axis direction (optical-axis AX direction) of the lower surface (pattern surface) of the reticle R. It is a flowchart for demonstrating the device manufacturing method of this invention. It is a flowchart which shows the detailed example of step 216 of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 30 ... Reticle stage drive part (a part of drive system), 40 ... Controller (a part of a calculation apparatus and a position detection apparatus), 50 ... Main controller (a control apparatus, a part of a drive system), 56 ... Wafer stage drive Part (part of drive system), 100 ... exposure device, R ... reticle (mask), 160a ... irradiation system (part of position detection device), 160b ... light reception system (part of position detection device), PL ... projection Optical system, W ... wafer (object), DL ... detection light, S1 ... first photodetector (light receiving element), S2 ... second photodetector (light receiving element).

Claims (7)

An exposure apparatus for transferring a pattern formed on a mask onto an object via a projection optical system,
At least one point on the mask corresponding to at least one evaluation point in the field of view of the projection optical system is irradiated with detection light from the side opposite to the projection optical system, and the detection light is based on reflected light from the mask. A position detecting device for detecting position information regarding the optical axis direction of the projection optical system at a detection point corresponding to the at least one evaluation point on the pattern surface of the mask on which the pattern is formed;
A control device that controls a relative positional relationship between the pattern image of the mask and the object in the optical axis direction based on the position information detected by the position detection device when the pattern is transferred. Exposure device. The position detection device includes:
An irradiation system for irradiating the mask with the detection light from a direction inclined by a predetermined angle with respect to the optical axis of the projection optical system;
A light receiving system for receiving first and second reflected light from the pattern surface of the mask and the opposite surface of the mask of the detection light;
A predetermined calculation is performed based on light reception information of at least one of the first and second reflected lights from the light receiving system, and position information regarding the optical axis direction at the at least one detection point of the pattern surface is calculated. The exposure apparatus according to claim 1, further comprising: a calculation device. The light receiving system includes a light receiving element that receives the first and second reflected lights,
The calculation device calculates position information regarding the optical axis direction of the surface opposite to the pattern surface of the mask at the at least one detection point based on light reception information of the second reflected light, and the first The thickness of the mask at the detection point is calculated based on the light reception information of the second reflected light, and the pattern at the at least one detection point is calculated based on the calculated position information and information on the thickness of the mask. The exposure apparatus according to claim 2, wherein a position of the surface in the optical axis direction is calculated.   The calculation device is based on a distance between incident points of the first and second reflected light on a light receiving surface of the light receiving element, an incident angle of the detection light with respect to the mask, and a refractive index of the mask. The exposure apparatus according to claim 3, wherein a thickness of the mask at the detection point is calculated.   The position detection device irradiates a plurality of points on the mask individually corresponding to a plurality of evaluation points in a field of view of the projection optical system, respectively, with detection light from the opposite side of the projection optical system. The position information regarding the optical axis direction of the pattern surface at a plurality of detection points individually corresponding to the plurality of evaluation points is detected based on reflected light from the mask. The exposure apparatus according to any one of the above. A drive system that drives the mask and the object in synchronization with a predetermined scanning direction;
The exposure apparatus according to claim 5, wherein the plurality of detection points are arranged apart from each other at least in a non-scanning direction orthogonal to the scanning direction. A device manufacturing method including a step of transferring a pattern formed on a mask onto an object via a projection optical system using the exposure apparatus according to claim 1.

Images