JP4817700B2 - Exposure apparatus and method, and device manufacturing method - Google Patents

Description

  The present invention is used, for example, for manufacturing semiconductor devices such as ICs and LSIs, display devices such as liquid crystal panels, detection devices such as magnetic heads, imaging devices such as CCDs, and the like, and manufacturing fine patterns used in micromechanics. The present invention relates to an exposure apparatus and method.

  When manufacturing fine semiconductor elements such as semiconductor memories and logic circuits using photolithography (baking) technology, a circuit pattern drawn on a reticle (or mask) is projected onto a wafer or the like by a projection optical system. Conventionally, a projection exposure apparatus for transferring the image has been used.

  In a projection exposure apparatus, it is required to expose a circuit pattern of a reticle onto a wafer with higher resolution as semiconductor elements are miniaturized and densified. The resolution (minimum dimension that can be transferred) of the projection exposure apparatus is proportional to the wavelength of light used for exposure and inversely proportional to the numerical aperture (NA) of the projection optical system. NA is advancing. On the other hand, the chip pattern of one semiconductor element tends to increase in size, and further expansion of the exposure area is required for the projection exposure apparatus.

  In order to achieve these requirements, a projection optical system having a large exposure area and high resolving power is essential. However, the larger the exposure area and the higher the resolving power, the more the entire exposure area. It is difficult to maintain the imaging performance such as distortion at a predetermined accuracy. Therefore, a scanning type exposure apparatus ("" scans a reticle and wafer relative to a slit-shaped exposure region such as a rectangular shape or an arc shape) while transferring the reticle and the wafer relatively synchronously (scanning). It is also called “scanner”.)

  However, along with the further miniaturization of semiconductor elements in recent years, a scanner is required to have a resolution close to the limit, and a projection optical system having a larger NA is employed. Since the depth of focus becomes extremely shallow as the NA of the projection optical system increases, it is important to improve the accuracy of focusing (that is, alignment between the image plane position of the projection optical system and the surface position of the wafer). As a result, the imaging error due to the deformation of the reticle cannot be ignored.

  The reticle can be deformed by bending of the reticle itself, flatness of the reticle itself, deformation at the time of holding (sucking) the reticle on the reticle stage, and the like. Deformation when holding (sucking) the reticle occurs according to the surface shape of the suction part of the reticle stage and the surface shape of the reticle, and the amount of deformation differs depending on the combination. Therefore, the deformation of the reticle needs to be measured in a state where the reticle is actually held (adsorbed) on the reticle stage.

  Therefore, a surface shape detection system for detecting the surface shape of the reticle is arranged in a space between the projection optical system and the reticle stage and deviated in the scanning direction, and scanning exposure is performed via the surface shape detection system. An exposure apparatus has been proposed that detects the surface shape of a reticle (pattern surface thereof) during the run-up period (see, for example, Patent Document 1). The exposure apparatus of Patent Document 1 controls the imaging characteristics of the projection optical system or the focus position of the wafer based on the detection result of the surface shape detection system. Furthermore, the exposure apparatus of Patent Document 1 has a configuration in which a reference member is arranged on a reticle stage, and the surface shape detection system can be calibrated via the reference member.

A position detecting device configured to detect a position of the reticle in a direction substantially perpendicular to the reticle surface, the irradiation unit configured to guide light from the light source to the reticle surface and a light receiving unit configured to receive reflected light from the reticle surface; An exposure apparatus having the same has also been proposed (see, for example, Patent Document 2). The exposure apparatus of Patent Document 2 is characterized in that the incident angle of light incident on the reticle surface is 45 degrees or more in order to improve detection errors.
JP 11-45846 A JP 2003-264136 A

  When positioning with the reticle stage mounted on the reticle stage, generally, even if the same reticle is used, the positioning error is not zero, and the positioning is performed within a certain allowable range. The detection position of the detection system or position detection device fluctuates (that is, deviates from a predetermined detection position). In particular, when the detection position (detection light) of the surface shape detection system or position detection device straddles the boundary of the pattern, reflection from the reticle is caused by the difference in reflectance between the region with the pattern (chrome) and the region without the pattern (glass). Light is affected, and an error is included in the detected reticle shape.

  The exposure apparatus disclosed in Patent Document 1 has a surface shape detection system disposed at a position away from the projection optical system. Therefore, in order to detect the entire surface of the reticle, an extra stroke of the reticle stage is required (only by a distance arranged at a distance), and the exposure apparatus becomes large. When the surface shape detection system is calibrated, it is necessary to drive the reticle stage to a position where the surface shape detection system can detect a reference member arranged on the reticle stage for calibration. Therefore, an extra stroke of the reticle stage is required to calibrate the surface shape detection system. Further, if the stroke of the reticle stage becomes longer, the driving time becomes longer, resulting in a decrease in the throughput of the exposure apparatus.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a novel technique for measuring the shape of the pattern surface of a reticle.

In order to achieve the above object, an exposure apparatus according to one aspect of the present invention includes a reticle stage for holding a reticle , a projection optical system, and a target object stage for holding a target object. An exposure apparatus that projects a pattern of the reticle held on the reticle stage onto a target object via a projection optical system, the mark being held on the reticle stage, on the reticle and on the target stage Position measuring means for measuring the position of the reticle by measuring the relative position between the mark on the reticle and the mark on the reticle stage, and the optical axis of the projection optical system. Position detecting means for detecting the position of the pattern surface of the reticle in a parallel direction, and the position detecting means is a predetermined position on the pattern surface. In to perform the detection, and having a positioning means for positioning the reticle using the measurement results of the position measurement means.

An exposure apparatus according to another aspect of the present invention includes a reticle stage for holding a reticle , a projection optical system, and a target object stage for holding a target object , and through the projection optical system, An exposure apparatus that projects a pattern of the reticle held on the reticle stage onto a workpiece, the relative position between the mark on the reticle and the mark on the workpiece stage held by the reticle stage , Or position measuring means for measuring the position of the reticle by measuring the relative position between the mark on the reticle and the mark on the reticle stage, and the reticle in the direction parallel to the optical axis of the projection optical system. Position detecting means for detecting the position of the pattern surface, and the position of the pattern surface of the reticle with respect to the positional deviation of the reticle acquired in advance; By correcting the detection result of said position detecting means with out error, characterized by having a calculating means for calculating the shape of the pattern surface.

  According to still another aspect of the present invention, there is provided a device manufacturing method comprising: exposing a target object using the above-described exposure apparatus; and developing the exposed target object.

  Further objects and other features of the present invention will become apparent from the preferred embodiments described below with reference to the accompanying drawings.

  ADVANTAGE OF THE INVENTION According to this invention, the novel technique for measuring the shape of the pattern surface of a reticle can be provided.

  Hereinafter, an exposure apparatus according to one aspect of the present invention will be described with reference to the accompanying drawings. In addition, in each figure, the same reference number is attached | subjected about the same member and the overlapping description is abbreviate | omitted. FIG. 1 is a schematic sectional view showing the arrangement of an exposure apparatus 1 according to the present invention.

  As shown in FIG. 1, the exposure apparatus 1 mounts an illumination apparatus 100 that illuminates a reticle R on which a circuit pattern is formed, a reticle stage 200 on which the reticle R is mounted, a projection optical system 300, and a wafer W. A wafer stage 400, an alignment sensor 500, a reticle surface shape detection system 600, a reticle detection system 700, and a main controller 800.

  The exposure apparatus 1 is a projection exposure apparatus that exposes a workpiece W to a circuit pattern formed on a reticle R by, for example, a step-and-scan method or a step-and-repeat method. Such an exposure apparatus is suitable for a lithography process of submicron or quarter micron or less, and in the present embodiment, a step-and-scan type exposure apparatus (scanner) will be described below as an example.

  The illumination device 100 illuminates a reticle R on which a transfer circuit pattern is formed, and includes a light source unit 110 and an illumination optical system 120.

For the light source unit 110, for example, an ArF excimer laser with a wavelength of about 193 nm, a KrF excimer laser with a wavelength of about 248 nm, or the like can be used as the light source, but the type of the light source is not limited to the excimer laser. A 157 nm F ₂ laser or YAG laser may be used, and the number thereof is not limited. The light source that can be used for the light source unit 110 is not limited to a laser, and one or a plurality of lamps such as a mercury lamp and a xenon lamp can be used.

  When the light source unit 110 is a pulse light source (that is, a laser), on / off of exposure is switched by control of power supplied from a power source device for the pulse light source. When the light source unit 110 is a continuous light source (that is, a lamp), whether the exposure is on or off is switched by a shutter in the illumination optical system 120. However, in the present embodiment, as will be described later, since the illumination optical system 120 includes a movable blind (variable field stop) 125, the exposure may be switched on and off by opening and closing the movable blind 125.

  The illumination optical system 120 is an optical system that illuminates the reticle R. In the present embodiment, the illumination optical system 120 uniformly illuminates a rectangular slit-shaped illumination area IA. Thereby, the circuit pattern of the reticle R in the slit-shaped illumination area IA is transferred onto the workpiece W via the projection optical system 300 described later. As shown in FIG. 1, the illumination optical system 120 includes an illumination light shaping optical system 121, a fly-eye lens 122, a condenser lens 123, a field stop 124, a movable blind 125, and a relay lens system 126. .

  Illumination light from the light source unit 110 is shaped into a predetermined beam diameter by the illumination light shaping optical system 121 and reaches the fly-eye lens 122. A number of secondary light sources are formed on the exit surface of the fly-eye lens 122. The illumination light from the secondary light source is collected by the condenser lens 123 and reaches the movable blind (variable field stop) 125 through the fixed field stop 124. In FIG. 1, the field stop 124 is disposed closer to the condenser lens 123 than the movable blind 125, but may be disposed closer to the relay lens system 126.

  The field stop 124 has a rectangular slit-shaped opening, and the light beam that has passed through the opening becomes a light beam having a rectangular slit-shaped cross section and enters the relay lens system 126. The longitudinal direction of the slit-shaped opening is assumed to be a direction perpendicular to the paper surface (FIG. 1).

  The movable blind 125 includes two light shielding plates 125a and 125b that define the width in the scanning direction (X direction), which will be described later, and two light shielding plates (not shown) that define the width in the direction perpendicular to the scanning direction (non-scanning direction). Composed. The light shielding plates 125a and 125b that define the width in the scanning direction are supported by the driving units 125c and 125d so that they can be independently driven in the scanning direction. Further, a light shielding plate (not shown) that defines the width in the non-scanning direction is supported so that it can be driven independently. The operations of the drive units 125c and 125d of the movable blind 125 and the drive unit in the non-scanning direction are controlled by the blind control unit 810.

  In the present embodiment, illumination light is irradiated only within a desired exposure area set by the movable blind 125 in the slit-shaped illumination area IA on the reticle R set by the fixed field stop 124.

  The relay lens system 126 is a lens system that conjugates the movable blind 125 and the reticle R (pattern surface thereof). The relay lens system 126 is a bilateral telecentric optical system, and telecentricity is maintained in the slit-shaped illumination area IA on the reticle R.

  The reticle R is made of, for example, quartz, and a circuit pattern (or image) to be transferred is formed on the reticle R, and is supported and driven by the reticle stage 200. The diffracted light emitted from the reticle R passes through the projection optical system 300 and is projected onto the workpiece W. The reticle R and the workpiece W are arranged in an optically conjugate relationship. Since the exposure apparatus 1 of the present embodiment is a scanner, the pattern of the reticle R is transferred onto the object to be processed W by scanning the reticle R and the object to be processed W at a speed ratio of the reduction magnification ratio. Specifically, the image of the circuit pattern on the reticle R defined by the slit-shaped illumination area IA and the movable blind 125 is projected and exposed on the workpiece W via the projection optical system 300.

  Reticle stage 200 supports reticle R via a reticle chuck (not shown) and is connected to stage moving mechanism 220. The position of reticle stage 200 is detected by interferometer 210 and driven by stage moving mechanism 220. In this embodiment, reticle stage 200 is driven by stage moving mechanism 220 to scan reticle R in the scanning direction (+ X direction or −X direction). Here, in the secondary plane perpendicular to the optical axis of the projection optical system 300, the scanning direction of the reticle R with respect to the slit-shaped illumination area IA is the + X direction (or -X direction), and the optical axis of the projection optical system 300 is Let the parallel direction be the Z direction.

  The projection optical system 300 is an optical system that projects the pattern of the reticle R onto the workpiece W. The projection optical system 300 includes an optical system including only a plurality of lens elements, an optical system (catadioptric optical system) having a plurality of lens elements and at least one concave mirror, a plurality of lens elements, and at least one kinoform. An optical system having a diffractive optical element such as an all-mirror optical system can be used. When correction of chromatic aberration is required, a plurality of lens elements made of glass materials having different dispersion values (Abbe values) can be used, or the diffractive optical element can be configured to generate dispersion in the opposite direction to the lens element. To do.

  The object to be processed W is a wafer in this embodiment, but widely includes a liquid crystal substrate and other objects to be processed. A photoresist is applied to the workpiece W.

  Wafer stage 400 supports workpiece W by a wafer chuck (not shown) and is connected to stage moving mechanism 420. The position of wafer stage 400 is detected by interferometer 410 and driven by stage moving mechanism 420. For example, the wafer stage 400 positions the object to be processed W in a plane perpendicular to the optical axis of the projection optical system 300, and scans the object to be processed W in the ± X direction, and the object W to be processed. It is composed of a Z stage that is positioned in the Z direction. The wafer stage 400 includes a reference mark FM having a mark for baseline measurement, a mark for alignment of the reticle R, or the like.

  When the reticle R pattern is exposed to each shot area on the workpiece W via the projection optical system 300 by the step-and-scan method, the reticle stage 200 is set by the field stop 124. The reticle R is scanned at a speed VR in the −X direction (or + X direction) with respect to the slit-shaped illumination area IA. Further, when the projection magnification of the projection optical system 300 is β, the wafer stage 400 moves the workpiece W in the + X direction (or −X direction) at the speed VW (= β · VR) in synchronization with the scanning of the reticle R. ). As a result, the circuit pattern of the reticle R is sequentially transferred to the shot area on the workpiece W.

  The alignment sensor 500 is disposed above the wafer W. In this embodiment, the alignment sensor 500 detects an alignment mark on the wafer W by an off-axis method. The detection result of the alignment sensor 500 is processed by the alignment control unit 830 and sent to the main control unit 800. The main controller 800 controls the positioning operation and scanning operation of the wafer stage 400 via the stage moving mechanism 420 as will be described later.

  The reticle surface shape detection system 600 is disposed between the reticle stage 200 and the projection optical system 300, and has a function as a shape measurement unit that measures the shape of the reticle R, as will be described later. The detection result of reticle surface shape detection system 600 is processed by detection system control unit 820 and sent to main control unit 800.

  The reticle surface shape detection system 600 has the same configuration as the reticle surface position detection system of the exposure apparatus proposed by the present applicant in Japanese Patent Application Laid-Open No. 2003-297726. explain. The basic detection principle of the reticle surface shape detection system 600 will be described. The reticle pattern surface, which is the test surface, is irradiated with a light beam from an oblique direction, and the incident position of the light beam reflected by the test surface on the predetermined surface is positioned. Detection is performed by a detection element, and position information in the Z direction (the optical axis direction of the projection optical system 300) of the test surface is detected from the position information. In addition, reticle surface shape detection system 600 (detection system control unit 820) projects a plurality of light beams set in a direction substantially orthogonal to the scanning direction onto a plurality of measurement points on the test surface, and at each measurement point. The tilt information of the test surface is calculated using the obtained position information in the Z direction. Furthermore, by scanning the reticle R, it is possible to measure position information in the Z direction at a plurality of measurement points in the scanning direction. From these position information, the detection system control unit 820 calculates the surface shape of the pattern surface of the reticle R (that is, the shape of the reticle R).

  The reticle detection system 700 is disposed above the reticle R and has a function as position detection means for detecting the position of the reticle R. As shown in FIG. 2, reticle detection system 700 includes fiber 710, relay lens 720, half mirror 730, objective lens 740, mirror 750, relay lens 760, detection unit 770, and calculation unit 780. Have Here, FIG. 2 is a schematic cross-sectional view showing the configuration of the reticle detection system 700.

  The reticle detection system 700 guides the illumination light branched from the illumination optical system 120 through the fiber 710. The illumination light guided by the fiber 710 is guided to the reticle R through the relay lens 720, the half mirror 730, the objective lens 740, and the mirror 750, and the alignment mark and projection optics arranged on the reticle R. The reference mark FM on the wafer stage 400 is irradiated through the system 300. The alignment mark arranged on the reticle R and the image of the reference mark FM on the wafer stage 400 are formed on the detection unit 770 via the mirror 750, the objective lens 740, the half mirror 730, and the relay lens 760. . The detection result of the detection unit 770 is processed by the calculation unit 780 and sent to the main control unit 800.

  The main control unit 800 includes a CPU and a memory, and controls the operation of the exposure apparatus 1. The CPU includes any processor of any name such as MPU and controls the operation of each unit. The memory is composed of ROM and RAM, and stores firmware that operates the exposure apparatus 1. The main controller 800 is connected to the blind controller 810, the detection system controller 820, the alignment controller 830, and the stage moving mechanisms 220 and 420. In the present embodiment, the main control unit 800 controls the position of the reticle R with respect to the reticle surface shape detection system 600 based on the detection result of the reticle detection system 700, as will be described later. In other words, the main control unit 800 also has a function as a shape acquisition unit that acquires the shape of the reticle R in cooperation with the reticle surface shape detection system 600. The main control unit 800 controls the positioning operation and scanning operation of the wafer stage 400 via the stage moving mechanism 420. Needless to say, the main control unit 800 may be configured integrally with the functions of the blind control unit 810, the detection system control unit 820, and the alignment control unit 830.

  Here, the relationship between reticle detection system 700 and reticle surface shape detection system 600 will be described. The present embodiment is characterized in that the detection position of the reticle surface shape detection system 600 is corrected based on the position of the reticle R detected by the reticle detection system 700. FIG. 3 shows the reticle R, the pattern area RPA formed in the reticle R, and the detection position (detection point) DP of the reticle surface shape detection system 600. Referring to FIG. 3, five detection points DP of reticle surface shape detection system 600 are configured in a direction orthogonal to the scanning direction. Further, by scanning the reticle R, seven rows of detection points DP are configured in the scanning direction. The arrangement of the detection points DP shown in FIG. 3 is in a state in which the reticle R is positioned with respect to the reticle stage 200 as designed.

  FIG. 4 shows detection points DP ′ (black circles) of reticle surface shape detection system 600 when reticle R is scanned with respect to reticle stage 200 while being displaced by X in a direction orthogonal to the scanning direction. Further, the detection point DP ′ of the reticle surface shape detection system 600 when the reticle R is scanned with respect to the reticle stage 200 while being positioned with a deviation of θ in the rotation direction about the optical axis of the projection optical system 300. '(Black circle) is shown in FIG. 4 and 5, the design detection point DP (that is, the state shown in FIG. 3) for the reticle R (pattern thereof) is shown as a white circle.

  The reticle surface shape detection system 600 ideally calculates the shape of the reticle R from the detection result at the position of the detection point DP shown in FIG. 3, but as shown in FIGS. On the other hand, when the reticle R is arranged so as to be displaced, the shape of the reticle R is calculated from the detection results at the positions of the detection points DP ′ and DP ″ for the positional displacement amounts X and θ of the reticle R. . Therefore, the pattern distribution of the reticle R is different between the position of the detection point DP and the positions of the detection points DP ′ and DP ″, that is, the detection point in the chrome part (or glass part) is in the glass part (or chrome part). Or the ratio (reflectance) between the chromium portion and the glass portion inside the detection point region is different, and the detection rate is lowered. In other words, the reflected light from the reticle R is affected by fluctuations in the detection position of the reticle surface shape detection system 600, and the detection accuracy of the shape of the reticle R is significantly reduced.

  Therefore, in the present embodiment, the reticle detection system 700 changes the position of the reticle R, that is, the scanning direction of the reticle R with respect to the reticle stage 200, the direction orthogonal to the scanning direction, and the rotation direction about the optical axis of the projection optical system 300. The amount of displacement is detected, and the detection result is reflected in the correction of the detection position of the reticle surface shape detection system 600. For example, the displacement of the reticle R in the scanning direction is corrected by controlling the detection start position of the reticle surface shape detection system 600 by the detection system control unit 820. Further, for the positional deviation of the reticle R in the direction orthogonal to the scanning direction, the reticle stage 200 is driven to correct the positional deviation of the reticle R. Similarly, the reticle stage 200 is driven to correct the positional deviation of the reticle R with respect to the positional deviation in the rotation direction around the optical axis of the projection optical system 300. Alternatively, correction is performed by driving the reticle stage 200 in the scanning direction and a direction orthogonal to the scanning direction and moving the reticle R in stages. Thereby, the reticle surface shape detection system 600 can always measure the surface shape at a constant position (that is, a predetermined detection position) with respect to the reticle R (pattern), and the shape of the reticle R can be accurately determined. It can be measured.

  If the detection error of the shape of the reticle R with respect to the positional deviation of the reticle R is known in advance, the deviation detection points (for example, the detection points DP ′ and DP ″) are corrected without correcting the positional deviation of the reticle R. It is also possible to directly correct the shape of the reticle R calculated from the detection result at, in other words, to calculate the shape of the reticle R from the position deviation of the reticle R and the detection result at the shifted detection point. .

  Alignment of the image plane position of the projection optical system 300 by measurement of the shape of the reticle R and the surface position of the workpiece W, that is, correction of the imaging characteristics of the projection optical system 300 based on the measurement result of the shape of the reticle R; Alternatively, the correction of the imaging characteristics by adjusting the position of the wafer stage 400 during scanning is disclosed in Japanese Patent Laid-Open No. 11-45846, which is shown as a prior art, and thus detailed description thereof is omitted here.

  As described above, according to the present embodiment, it is possible to provide a novel surface shape measurement technique that copes with the fact that the measurement result of the reticle pattern surface shape varies depending on the position of the reticle with respect to the reticle stage.

  In FIG. 1, reticle surface shape detection system 600 is arranged in a space between reticle stage 200 and projection optical system 300, and a measurement position (that is, a position of a detection point) is set at the optical axis center position of projection optical system 300. However, as shown in FIG. 6, it has a position shifted in the scanning direction from the center position of the optical axis of the projection optical system 300, that is, a measurement position (that is, a position of a detection point) outside the transfer target area. It is also possible to arrange the reticle surface shape detection system 600 as described above. Here, FIG. 6 is a schematic sectional view showing another configuration of the exposure apparatus 1 of the present invention.

  Although not shown in FIG. 6, a reticle detection system 700 is disposed above the reticle R, as in FIG. 1, and the alignment mark on the reticle R and the wafer stage 400 are positioned on the wafer stage 400. The position of the reticle R can be detected by measuring the relative position of the reference mark FM. By correcting the detection position of the reticle surface shape detection system 600 based on the detection result of the reticle detection system 700, it becomes possible to always detect the surface shape at a predetermined position with respect to the reticle R (pattern). It becomes possible to measure the shape of the reticle R with high accuracy.

  Further, as shown in FIG. 7, a reference surface SP in which a reflecting surface and measurement marks are formed on the reticle stage 200 at substantially the same height as the pattern surface of the reticle R in the optical axis direction of the projection optical system 300. And a reference plate RFM constituting a reference mark for positioning the reticle R, and a reticle position detection system 900 may be arranged above the reticle R. Here, FIG. 7 is a schematic sectional view showing another configuration of the exposure apparatus 1 of the present invention.

  Differences between the reticle position detection system 900 and the reticle detection system 700 will be described. The reticle detection system 700 is disposed at a position where the reference mark FM on the wafer stage 400 can be detected via the projection optical system 300, whereas the reticle position detection system 900 includes the reference mark RFM and the reticle. It is arranged at a position where an alignment mark on R can be detected.

  8 and 9 are schematic perspective views showing the reference plate RFM and the reference surface SP arranged on the reticle stage 200. FIG. As shown in FIG. 8, the reticle R is held (adsorbed) by the reticle chuck 230 of the reticle stage 200. The reticle chuck 230 is configured with two front and rear positions with respect to the scanning direction, and similarly with two front and rear positions with respect to the non-scanning direction, and holds (sucks) the reticle R at four positions. Further, the reference plate RFM is disposed between the reticle chucks 230 of the reticle chuck 230.

  As shown in FIG. 9, reticle position detection system 900 includes a two-lens detection system. The alignment mark on the reticle R is arranged at a position that can be detected by the reticle position detection system 900 together with the reference plate RFM in a state where the reticle R is held (sucked) by the reticle chuck 230. A reference plane SP is formed at a position shifted from the reticle R in the scanning direction.

  The reticle surface shape detection system 600 can be calibrated by moving the reticle stage 200 and driving the reference surface SP to the detection position of the reticle surface shape detection system 600. Note that a method for calibrating the reticle surface shape detection system 600 is disclosed in Japanese Patent Application Laid-Open No. 11-45846, and a detailed description thereof is omitted here.

  In the present embodiment, since the alignment mark on the reference plate RFM and the reticle R are arranged on the reticle stage 200, the reticle position detection system 900 is configured so that the reference mark RFM and the reticle are within the stroke of the reticle stage 200. What is necessary is just to arrange | position in the position which can measure the mark for alignment on R. In addition, the reticle position detection system 900 is positioned at a position where the alignment mark on the reference plate RFM and the reticle R can be measured at the position of the reticle stage 200 where the reticle reference surface SP can measure the calibration reference surface SP. Has been placed. Thereby, when the position of the reticle R is detected by the reticle position detection system 900, the reticle surface shape detection system 600 can be calibrated, and the reticle stage 200 is calibrated for the calibration of the reticle surface shape detection system 600. Driving to the position is not necessary, and unnecessary expansion of the stroke of reticle stage 200 can be suppressed.

  Further, the calibration position of the reticle surface shape detection system 600 (ie, the detection position of the reference surface SP), the detection position of the reticle position detection system 900 (ie, the position for detecting the position of the reticle R), and the attachment / detachment position of the reticle R are the same. Thus, during the transition from the reticle R replacement operation to the pattern transfer exposure operation, the reticle surface shape detection system 600 is calibrated, the reticle R position is detected, the reticle R position is corrected, and the reticle R shape is corrected. The shape of the reticle R can be measured with high accuracy without causing a reduction in throughput.

  The reticle surface shape detection system 600 may be arranged on both sides of the projection optical system 300 with respect to the scanning direction, as shown in FIG. The detection results of the two reticle surface shape detection systems 600 are processed by the detection system control unit 820 and sent to the main control unit 800. By arranging the reticle surface shape detection systems 600 on both sides of the projection optical system 300 with respect to the scanning direction, the stroke of the reticle stage 200 required to detect the shape of the reticle R can be minimized. Here, FIG. 10 is a schematic sectional view showing another configuration of the exposure apparatus 1 of the present invention.

  The stroke of reticle stage 200 will be described with reference to FIGS. FIG. 11 is a partially enlarged view schematically showing the reticle R, the reticle surface shape detection system 600, and the projection optical system 300. As shown in FIG. In FIG. 11, LR is the length of the reticle R in the scanning direction, and L is the reticle from the optical axis of the projection optical system 300 when the reticle surface shape detection system 600 is arranged without physically interfering with the projection optical system 300. A indicates the distance to the detection position of the surface shape detection system 600, and A indicates the distance required for acceleration for the reticle stage 200 to reach the speed at the time of exposure. Note that when examining the stroke of the reticle stage 200, strictly speaking, it is necessary to consider the pattern area of the reticle R or the irradiation area of the reticle R, but in the present embodiment, the reticle surface shape detection system 600 includes: For comparison by arrangement, only dimensions necessary for the comparison are shown, and other dimensions are omitted.

  12 shows a case where the reticle surface shape detection system 600 is arranged on both sides of the projection optical system 300 with respect to the scanning direction (that is, the reticle R, the reticle surface shape detection system 600 and the projection optical system 300 shown in FIG. 10). It is a partial enlarged view showing typically. In FIG. 12, LR / 2 indicates a range (distance) in which the reticle surface shape detection system 600 can measure the shape of the reticle R in the scanning direction. Referring to FIG. 12, since the reticle surface shape detection system 600 is arranged on both sides of the projection optical system 300, the range LR of the reticle R in the scanning direction is measured by one reticle surface shape detection system 600. Can be halved. That is, the left half of the reticle R shown in FIG. 12 is measured by the reticle surface shape detection system 600A, and the right half of the reticle R shown in FIG. 12 is detected by the reticle surface shape detection system 600B.

  In the case of the configuration of the reticle surface shape detection system 600 shown in FIG. 11, the stroke ST required by the reticle stage 200 is expressed by the following Equation 1.

  On the other hand, in the case of the configuration of the reticle surface shape detection system 600 shown in FIG. 12, the stroke ST ′ required by the reticle stage 200 is expressed by the following Equation 2.

  Further, the difference between the stroke ST and the stroke ST ′ is expressed by Equation 3 below.

  Since the stroke of the reticle stage 200 can be shortened when ST> ST ′, the stroke of the reticle stage 200 is shortened when the condition shown in the following Equation 4 is satisfied, thereby preventing an increase in the size of the apparatus. it can. Formula 4 shows that the larger the size of the reticle R and the acceleration distance, the more effective.

  In recent years, in order to improve the throughput of the apparatus, the speed of the reticle stage 200 and the wafer stage 400 has been increased along with the higher output of the light source unit 110. As the speed increases, the acceleration distance of the reticle stage 200 also tends to increase. Therefore, by arranging the reticle surface shape detection systems 600 on both sides of the projection optical system 300 with respect to the scanning direction, the stroke of the reticle stage 200 is expanded. Therefore, it is possible to measure the shape of the reticle R with high accuracy.

  10 and 12, the reticle surface shape detection systems 600A and 600B measure the pattern surface of the reticle R in half, thereby preventing the stroke of the reticle stage 200 from expanding. However, since reticle surface shape detection systems 600A and 600B are detection systems having different configurations, calibration between the two reticle surface shape detection systems is required. Therefore, as shown in FIG. 13, the reticle surface shape detection systems 600A and 600B are configured to be able to measure the region B of the reticle R in addition to half of the pattern surface of the reticle R, which is shown in FIG. The reference surface SP that is not to be measured is arranged so as to be measurable by the reticle surface shape detection system 600A or 600B. Here, FIG. 13 is a partially enlarged view schematically showing the case where the reticle surface shape detection system 600 is arranged on both sides of the projection optical system 300 with respect to the scanning direction.

  For example, first, the reference surface SP is detected by the reticle surface shape detection system 600B, and the reticle surface shape detection system 600B is calibrated. Region B of reticle R is measured by reticle surface shape detection system 600B for which calibration has been completed. Next, the area B of the reticle R is measured by the reticle surface shape detection system 600A, and the reticle surface shape detection system 600A is calibrated based on the detection result of the reticle surface shape detection system 600B. When the area R of the reticle R is measured by the reticle surface shape detection systems 600A and 600B, it is performed not in the scanning operation but in a stationary state.

  Although the stroke of the reticle stage 200 is enlarged by the area B with respect to FIG. 12, it is sufficient if there is an area that can be measured by the reticle surface shape detection systems 600A and 600B. With such a configuration, calibration between the two reticle surface shape detection systems is possible, and the shape of the reticle R can be measured with higher accuracy.

  Until now, the reticle surface shape detection system 600 and the reticle detection system 700 or the reticle position detection system 900 have been arranged in different configurations. In such an arrangement, for example, when the position of the reticle surface shape detection system 600 changes due to thermal deformation of the structure supporting the reticle surface shape detection system 600, the position of the reticle R is detected by the reticle detection system 700 or the reticle position detection system 900. Even if the position of the reticle R is corrected, the position of the reticle surface shape detection system 600 is changed, and therefore the measurement position with respect to the reticle pattern is shifted.

  Therefore, as shown in FIG. 14, a reticle surface shape detection system 600 and a reticle detection system 700 or a reticle position detection system 900 are housed in a housing HG to constitute a reticle measurement system. As a result, even when the structure supporting the reticle measurement system changes due to thermal deformation or the like, the reticle surface shape detection system 600 and the reticle detection system 700 or the reticle position detection system 900 move together with the casing HG to detect the reticle surface shape. The relative position change between the detection position of system 600 and the detection position of reticle detection system 700 or reticle position detection system 900 can be reduced. For this reason, when measuring the shape of the reticle R, it is possible to always measure at a predetermined position with respect to the reticle R, so that the shape of the reticle R can be measured with high accuracy.

  As described above, according to the exposure apparatus 1, the shape of the reticle R is detected with high accuracy and focusing is performed (alignment between the image plane position of the projection optical system 300 and the surface of the workpiece W). And an excellent exposure performance can be exhibited. Further, an increase in the size of the apparatus and a decrease in throughput can be prevented.

  In the exposure, the light beam emitted from the light source unit 110 illuminates the reticle R, for example, with Koehler illumination by the illumination optical system 120. The light that passes through the reticle R and reflects the reticle pattern is imaged on the object 400 by the projection optical system 300. In the exposure, the exposure apparatus 1 can accurately align the image plane position of the projection optical system 300 and the surface of the workpiece W, prevent defocusing, etc., and achieve high throughput. Therefore, it is possible to provide a high-quality device (semiconductor element, LCD element, imaging element (CCD, etc.), thin-film magnetic head, etc.) with high economic efficiency.

  Next, an embodiment of a device manufacturing method using the exposure apparatus 1 will be described with reference to FIGS. 15 and 16. FIG. 15 is a flowchart for explaining how to fabricate devices (ie, semiconductor chips such as IC and LSI, LCDs, CCDs, and the like). Here, the manufacture of a semiconductor chip will be described as an example. In step 1 (circuit design), a device circuit is designed. In step 2 (mask production), a mask on which the designed circuit pattern is formed is produced. In step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the mask and the wafer. Step 5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer created in step 4. The assembly process (dicing, bonding), packaging process (chip encapsulation), and the like are performed. Including. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device created in step 5 are performed. Through these steps, the semiconductor device is completed and shipped (step 7).

  FIG. 16 is a detailed flowchart of the wafer process in Step 4. In step 11 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an insulating film is formed on the surface of the wafer. In step 13 (electrode formation), an electrode is formed on the wafer by vapor deposition or the like. Step 14 (ion implantation) implants ions into the wafer. In step 15 (resist process), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the exposure apparatus 1 to expose a circuit pattern on the mask onto the wafer. In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), the resist that has become unnecessary after the etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer. According to this device manufacturing method, it is possible to manufacture a higher quality device than before. Thus, the device manufacturing method using the exposure apparatus 1 and the resulting device also constitute one aspect of the present invention.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist. For example, the present invention can be applied to a step-and-repeat type exposure apparatus (also referred to as “stepper”) in which the wafer is moved stepwise to the exposure area of the next shot for every batch exposure of the wafer. it can.

It is a schematic sectional drawing which shows the structure of the exposure apparatus as one side surface of this invention. It is a schematic sectional drawing which shows the structure of the reticle detection system shown in FIG. It is a schematic plan view showing the positional relationship between the reticle, the pattern region formed in the reticle, and the detection position of the reticle surface shape detection system. It is a schematic plan view showing the positional relationship between the reticle, the pattern region formed in the reticle, and the detection position of the reticle surface shape detection system. It is a schematic plan view showing the positional relationship between the reticle, the pattern region formed in the reticle, and the detection position of the reticle surface shape detection system. It is a schematic sectional drawing which shows another structure of the exposure apparatus as one side surface of this invention. It is a schematic sectional drawing which shows another structure of the exposure apparatus as one side surface of this invention. FIG. 8 is a schematic perspective view showing a reference plate and a reference surface arranged on the reticle stage shown in FIG. 7. FIG. 8 is a schematic perspective view showing a reference plate and a reference surface arranged on the reticle stage shown in FIG. 7. It is a schematic sectional drawing which shows another structure of the exposure apparatus as one side surface of this invention. It is the elements on larger scale which show typically a reticle, a reticle surface shape detection system, and a projection optical system. It is the elements on larger scale which show typically the reticle, reticle surface shape detection system, and projection optical system which are shown in FIG. It is the elements on larger scale which show typically the case where a reticle surface shape detection system is arranged on both sides of a projection optical system to a scanning direction. It is a schematic sectional drawing which shows another structure of the exposure apparatus as one side surface of this invention. It is a flowchart for demonstrating manufacture of devices (semiconductor chips, such as IC and LSI, LCD, CCD, etc.). 16 is a detailed flowchart of the wafer process in Step 4 shown in FIG. 15.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exposure apparatus 100 Illumination apparatus 200 Reticle stage 300 Projection optical system 400 Wafer stage 500 Alignment sensor 600 Reticle surface shape detection system 700 Reticle detection system 800 Main control part 900 Reticle position detection system R Reticle W Object FM Reference mark RFM Reference plate SP Reference plane HG Housing DP, DP 'and DP''Detection position (detection point)

Claims (5)

A reticle stage for holding a reticle , a projection optical system, and a target object stage for holding a target object, and a pattern of the reticle held on the reticle stage via the projection optical system. An exposure apparatus that projects onto a workpiece,
Position for measuring the position of the reticle by measuring the relative position between the mark on the reticle and the mark on the workpiece stage, or the relative position between the mark on the reticle and the mark on the reticle stage. Measuring means;
Position detecting means for detecting the position of the pattern surface of the reticle in a direction parallel to the optical axis of the projection optical system;
An exposure apparatus comprising: positioning means for positioning the reticle using a measurement result of the position measuring means so that the position detecting means performs detection at a predetermined position on the pattern surface. . A reticle stage for holding a reticle , a projection optical system, and a target object stage for holding a target object, and a pattern of the reticle held on the reticle stage via the projection optical system. An exposure apparatus that projects onto a workpiece,
Position for measuring the position of the reticle by measuring the relative position between the mark on the reticle and the mark on the workpiece stage, or the relative position between the mark on the reticle and the mark on the reticle stage. Measuring means;
Position detecting means for detecting the position of the pattern surface of the reticle in a direction parallel to the optical axis of the projection optical system;
Calculating means for calculating the shape of the pattern surface by correcting the detection result of the position detection unit using the detection error of the position of the pattern surface of the reticle with respect to the positional deviation of the reticle acquired in advance. A featured exposure apparatus. The position of the reticle is a position in at least one of a scanning direction of the reticle stage, a direction orthogonal to the scanning direction of the reticle stage, and a rotation direction about the optical axis of the projection optical system. Item 3. The exposure apparatus according to Item 1 or 2.   The exposure apparatus according to claim 1, further comprising a housing that houses the position measurement unit and the position detection unit. Exposing the object to be processed using the exposure apparatus according to claim 1;
And developing the exposed object to be processed.