JP4590181B2 - Measuring method and apparatus, exposure apparatus, and device manufacturing method - Google Patents

Description

  The present invention generally relates to a measurement method and apparatus, and in particular, a measurement method for measuring wavefront aberration of a projection optical system or the like that transfers a pattern on a mask onto an object to be exposed using a light dividing means such as a diffraction grating. And an apparatus, and an exposure method and apparatus using the same. The measurement method and apparatus of the present invention are suitable for measurement of a projection optical system used in an exposure apparatus using EUV (Extreme Ultraviolet) light, for example.

  2. Description of the Related Art A projection type exposure apparatus that transfers a pattern formed on a mask (reticle) to an object to be exposed when manufacturing a semiconductor element or the like in a photolithography process is used. Such an exposure apparatus is required to accurately transfer a pattern on a reticle to an object to be exposed at a predetermined magnification. For this reason, it is important to use a projection optical system with good imaging performance and reduced aberrations. . Particularly in recent years, due to the demand for further miniaturization of semiconductor devices, the transfer pattern has become sensitive to aberrations of the optical system. Therefore, there is a demand for measuring the wavefront aberration of the projection optical system with high accuracy.

As an apparatus for measuring the wavefront aberration of a projection optical system with high accuracy, PDI and shearing interference have been conventionally known (see Patent Documents 1 and 2 and Non-Patent Documents 1 to 3). These interferometry methods typically use light splitting means such as a diffraction grating that splits the beam of measurement light.
JP-A-64139 US Pat. No. 5,835,217 Daniel Malacara, “Optical Shop Testing”, John Wiley & Sons, Inc. 231 (1978) Patrik P.M. Nauleau and Kenneth A .; Goldberg, J.M. Vac. Sci. Technol. B 18 (6), (2000) K. MURAKAMI et. al: Proc. SPIE Vol. 5307 Emerging Lithographic Technologies VII (2003) 257

  High-accuracy wavefront aberration measurement, for example, the measurement accuracy of the wavefront aberration of an EUV projection optical system is required to be as high as 0.1 nm. For such high-accuracy measurement, the interferometer components are also required to have high accuracy. Is done. For example, the surface accuracy of the optical elements constituting the interferometer or the pattern accuracy of the diffraction grating used for the light splitting means is important. The surface accuracy can be made somewhat insensitive by configuring the interferometer so that the optical path of the interferometer is a common path, and allowing the divided beams to pass through almost the same optical path. However, there has been no means for correcting and analyzing the pattern error of the diffraction grating.

Accordingly, the present invention is an exemplary object to provide an advantageous method and apparatus for measuring the reduction of the measurement error caused by the light dividing means.

Measurement method according to one aspect of the present invention utilizes a light dividing means constituted by connecting a plurality of regions having aligned to arranged pattern line respectively dividing the light beam of the measurement light, the test optical in the resulting Ru measuring method wavefront aberration of the interference fringes measured by the target optical system obtained by interference the measurement light passing through the system, from the size of the area in that direction in a direction parallel to the front Symbol pattern line and performing measurement of the interference fringes plurality of positions in each of the large amount only the light dividing means varies by moving the light splitting means, the step of averaging the results of a plurality of said measurements at said plurality of locations When, characterized by having a, and give Ru step the wavefront aberration on the basis of data obtained by the averaging. The light splitting means is, for example, a diffraction grating. It said pattern lines in each region of the light splitting means, for example, Ru is created by electron optics of an electron beam exposure apparatus. The interference may be based on point diffraction interferometry, line diffraction interferometry, or shearing interferometry.

Another exposure method as aspects of the present invention includes the wavefront aberration Ru give steps of the target optical system using the measuring method described above, the target optical system based on the obtained the wavefront aberration and adjusting, and having the steps of: exposing an object using the adjusted for such has been the target optical system.

Another measuring device as aspects of the present invention, there is provided a resulting Ru measuring device wavefront aberration of the target optical system by measuring the interference fringes obtained by interference measurement light passing through the target optical system, alignment is constructed by connecting a plurality of areas having to arranged pattern line respectively, larger than the size of the area in that direction in a direction parallel to the measurement light and the optical splitter for splitting the light, before Symbol pattern line characterized by having a drive means Before moving the light splitting means by an amount, and means that turn into averaging the results of the plurality of measurements at a plurality of positions of different said light splitting means by said movement by said driving means And

An exposure apparatus according to still another aspect of the present invention includes a projection optical system, an exposure apparatus that exposes an object with an exposure light via the mask and the projection optical system, before Symbol projection optical system the has a measuring device according to claim 7, target optical system, characterized in that. The exposure light is, for example, extreme ultraviolet light having a wavelength of 20 nm or less.

A device manufacturing method according to another aspect of the present invention includes the steps of exposing an object using the above exposure apparatus, and a step of developing the exposed object that has been exposed in the step. The claim of the device manufacturing method that exhibits the same operation as that of the above-described exposure apparatus extends to the intermediate and final device itself. Such devices include semiconductor chips such as LSI and VLSI, CCDs, LCDs, magnetic sensors, thin film magnetic heads, and the like.

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

According to the present invention, for example, it is possible to provide a measurement method and apparatus that are advantageous in reducing measurement errors caused by light splitting means.

  In this embodiment, an EUV projection optical system interferometer will be described as an example. However, the present invention is not limited to the EUV projection optical system. The inventor first analyzed the patterning error of the diffraction grating constituting the light splitting means. Since EUV is absorbed by almost all substances, a thin film-like substance, for example, a Ta film having a thickness of several hundred nm, is patterned and etched to form a hole, thereby forming a diffraction grating. For patterning, an electron beam is used as a normal method of this kind of microfabrication. In the case of an electron beam, since the screen size for scanning the electron beam cannot be made large, it is usual to create a large drawing area by connecting small screens. The problem in this case is the connection accuracy between the screens (referred to as “stitching accuracy”).

  In this embodiment, when measuring the wavefront aberration of the test optical system, the diffraction is performed by measuring a plurality of times while shifting by a predetermined amount in the direction of the pattern line constituting the diffraction grating, and averaging the measurement data of the plurality of times. The variation in error between regions constituting the lattice is made uniform. The shift amount is preferably larger than the screen size of the electron optical system of the electron beam lithography apparatus for creating the diffraction grating. As a result, it is possible to effectively correct the stitching error.

  Hereinafter, with reference to FIG. 1, a measurement apparatus 10 using PDI according to an embodiment of the present invention will be described. Here, FIG. 1 is a schematic optical path diagram of the measuring apparatus 10. The measuring apparatus 10 includes a first mask 12, a light splitting means 14 such as a diffraction grating (grating-type beam splitter in this embodiment), driving means 16 and 24 for the light splitting means 14, and a test optical system. As a projection optical system 18, a pinhole mask 20 as a second mask, a stage 22 for placing and driving the second mask 20, a driving means 24 for the stage 22, a detection unit 26, and a control Part 28.

  The first mask 12 is provided with a spherical hole generating pinhole 12a on the object side. The second mask 20 is an image-side spherical surface generation mask, and has a pinhole 20a and a window 20b for passing the test light. The second mask 20 can take out only a desired order by blocking light of other orders generated by the diffraction grating 14. The driving unit 16 drives the light splitting unit 14 in a direction parallel to the pattern line of the diffraction grating (X direction) and a direction orthogonal thereto (Y direction). The driving unit 24 drives the stage 22 in the optical axis direction and in a direction perpendicular to the optical axis direction. The drive means 16 and 24 are comprised from a linear motor, for example.

  The detection unit 26 is a detector or camera such as a back-illuminated CCD that is an interference fringe observation means. In addition to controlling each unit, the control unit 28 performs arithmetic processing for averaging the contrast of the interference fringes detected by the detection unit 26. In addition, the control unit 28 performs wavefront analysis using the averaged measurement data, and calculates the wavefront aberration of the optical system 18 to be measured. The control unit 28 has a memory for storing the driving amount and direction of the driving means 16 and the flowchart shown in FIG.

  Light emitted from a light source (not shown) is condensed on a pinhole 12a disposed on the first mask 12 by a light collecting system (not shown). The measurement light after passing through the pinhole 12a forms a reference spherical wave and travels toward the optical system 18 to be tested. A diffraction grating 14 disposed between the first mask 12 and the projection optical system 18 is disposed in parallel to a direction perpendicular to the paper surface, divides the measurement light in the y-axis direction, and has a direction corresponding to the pitch of the diffraction grating. Direct the light on.

  Each diffracted light is condensed on the image plane by the test optical system 18. Of the light collected by the test optical system 18, the 0th-order light having a large light amount is condensed on the pinhole 20a of the second mask 20, and the first-order diffracted light having a small light amount is collected on the window 20b. Of the two lights that have passed through the second mask 20, the 0th-order light passes through the pinhole 20a and becomes a spherical wave without aberration. That is, if the diameter of the pinhole is, for example, ½ or less of the Rayleigh limit, which is a well-known index of resolution, that is, a value smaller than the resolution limit of the optical system 18 to be measured, It has been known that the light passing therethrough is cut in the spread due to the aberration of the projection optical system to generate an ideal spherical wave. The ideal spherical wave generated in this way becomes a reference spherical wave, and the wavefront of the projection optical system is measured by interfering with the wavefront to be tested described above. Since the first-order diffracted light passes through the window 20b having an opening sufficiently larger than the diffraction limit, it becomes a wavefront on which the aberration information of the projection optical system 18 is placed. The zero-order light and the first-order diffracted light form interference fringes after passing through the second mask 20, and this is observed by the detection unit 26. In this state, when the control unit 28 scans the diffraction grating 14 in the direction orthogonal to the pattern line (Y-axis direction) via the driving unit 16, the diffracted light undergoes a phase shift and measures the aberration of the optical system 18 to be measured. be able to.

  The pinhole 12a of the first mask 12 and the pinhole 20a of the second mask 20 are sufficiently small, and the wavefront of the light after emitting the pinhole is very close to an ideal spherical wave. Therefore, it is possible to guarantee the absolute value of the aberration of the optical system 18 to be measured with very high accuracy. In addition, since the 0th-order light and the 1st-order diffracted light pass through almost the same optical path, stable and very high reproducibility can be realized.

  Here, when measuring the wavefront of the optical system 18 to be measured, the stitching accuracy of the diffraction grating 14 becomes a problem. When the measurement light is ultraviolet light, the light splitting means 14 can use an amplitude division beam splitter using a film formed on a glass material. However, when the measurement light is EUV, it corresponds to glass. Since there is no such a good transmissive material, the light splitting means 14 uses a wavefront split beam splitter.

  Hereinafter, problems of the latter type of light splitting means 14 will be described with reference to FIG. Here, FIG. 2A is a plan view of a diffraction grating as the light splitting means 14, and FIG. 2B is a partially enlarged plan view of the grating pattern. As shown in FIG. 2B, the diffraction grating 14 is configured by connecting a plurality of regions or blocks 14a, 14b, and 14c having a pattern aligned in the arrow direction.

  As shown in FIG. 2B, the pattern lines between the regions are slightly shifted. This is a phenomenon that occurs because the grating is drawn with an electron beam, and is a joining error called a stitching error. The drawing area of the electron beam exposure apparatus is usually sufficiently smaller than the total drawing area of the grating. Therefore, after writing one screen with the electron beam optical system, the drawing object is moved to connect the drawing areas, and the entire pattern is formed. Stitching accuracy between the drawing regions reaches a value of 20 to 30 nm. Therefore, for example, if the grating has a pitch of 2 microns, an error reaching λ / 100 may be generated.

  On the other hand, the wavefront aberration of recent projection optical systems has been required to be measured up to the fine characteristics of the wavefront. When the wavefront aberration is expressed by the Zernike function, it is sufficient to express from the first term to the 36th or 37th term. However, it is understood that the system cannot be evaluated correctly unless the higher order terms are taken into consideration. This is because. In particular, it is known that residues that cannot be expressed by the basic low-order terms up to 36 or 37 terms appear as flare during imaging. The flare is directly affected by the roughness of the surface processing and increases in inverse proportion to the square of the wavelength. For this reason, flare is accompanied by the recent shortening of the exposure light wavelength (for example, transition from KrF excimer laser (wavelength: about 248 nm) to ArF excimer laser (wavelength: about 193 nm) or EUV light (wavelength: about 13.5 nm)). The effect has become prominent.

  The fact that the fine behavior of the wavefront must be measured accurately means that each light beam divided by the light splitting means must be split in the same way. This corresponds to an improvement in surface accuracy in the conventional amplitude division beam splitter, and corresponds to an improvement in surface accuracy and pattern drawing accuracy in the wavefront division beam splitter.

  However, if there is a stitching error as shown in FIG. 2B, high measurement accuracy cannot be maintained. Such a state will be described with reference to FIGS. Here, FIG. 3 is a schematic diagram for explaining the imaging of the measurement light. FIG. 4A is an optical path perspective view showing a state in which the light beam is split by the light splitting unit 14 that is ideally formed (that is, has no stitching error). FIG. 4B is an optical path perspective view showing a state in which the light beam is split by the light splitting means 14 having a stitching error. First, as shown in FIG. 3, an imaging light beam 2 having a conical shape and representative rays 4 and 6 therein are considered. In the case of FIG. 4B, a phase difference occurs between the rays 4 and 6 after passing due to the stitching error, but such a phase difference does not occur in FIG. 4A.

  In the measuring apparatus 10 shown in FIG. 1, since the primary light that has passed through the light splitting means 14 passes through the optical system 18 to be detected and then passes through the window 20b to become the wavefront to be detected, the stitching error is directly measured by the wavefront measurement. Is understood to affect In contrast, the zero-order light that has passed through the minute pinhole 20a has its stitching error removed in the process of passing through the pinhole 20a. For this reason, it becomes difficult for the detection unit 26 to observe and correct interference fringes including stitching errors.

  Therefore, in this embodiment, in order to correct the stitching error and improve the measurement accuracy, the measurement is performed plural times by moving in the direction in which the pattern line extends (the arrow direction in FIG. 2B) and averaging. ing. Conventionally, PDI uses a phase scanning method that detects by scanning in a direction (Y direction shown in FIG. 1) perpendicular to the direction in which the pattern lines extend (X direction shown in FIG. 1). In the embodiment, characteristically, the light dividing means 14 is moved via the driving means 16 in a direction orthogonal to the X direction (X direction shown in FIG. 1), and phase scanning is performed again to average the results. As a result, it is possible to correct a systematic error that exists constantly, such as a stitching error. The shift amount is desirably a value larger than the screen size of the electron optical system of the electron beam exposure apparatus. Furthermore, the measurement accuracy can be improved by performing such a shift in the linear direction a predetermined number of times, for example, four times.

  Hereinafter, the measurement method of the present embodiment will be described with reference to FIG. Here, FIG. 5 is a flowchart for explaining the measurement method of the present embodiment.

  First, the test optical system 18 is set (step 102). Next, the control unit 28 sets the number of measurements K to 0 (step 104). Next, the control unit 28 drives the stage 24 to position the pinhole 20a of the second mask 20. The positioning is performed by aligning the condensing point of the test optical system 18 by the zero-order light of the diffraction grating 14 with the center of the pinhole 20a of the pinhole mask 20.

  Next, the control unit 28 performs PDI measurement, and performs multi-bucket interference fringe measurement through the detection unit 26 while phase-shifting the light splitting unit 14 in the Y direction shown in FIG. 106), aberration measurement data is acquired (step 108). In the phase shift method, five, nine, or more interference fringes are measured by the detection unit 26 while moving the grating by 1/4 or 1/8 pitch of the grating interval.

  Next, the control unit 28 determines whether or not the number of times of measurement K has reached a predetermined number of times N (for example, 4 times) (Step 110). The dividing means is shifted by a predetermined amount in the pattern line direction (X direction shown in FIG. 1) (step 112), the number of measurements is updated to K + 1 (step 114), and the process returns to step 106. If the control unit 28 determines that the predetermined number of times has been reached in step 110, the control unit 28 averages the N aberration measurement data (step 116), performs a wavefront analysis on the averaged data (step 118), and performs a test. The wavefront aberration of the optical system 18 is acquired. As described above, the measurement method of the present embodiment includes steps 104, 110, 112, 114, and 116 to improve measurement accuracy and correct stitching errors. In particular, the improvement of the accuracy of random components is remarkable.

  FIG. 6 is a schematic optical path diagram of a measuring apparatus 30 according to another embodiment of the present invention. The measurement apparatus 30 uses a shearing interferometry (DLSI method) using two gratings as a different measurement method in the EUV region. In FIG. 6, the control unit 28 and the like shown in FIG. 1 are omitted. The DLSI method is disclosed in Non-Patent Document 3.

  The measuring apparatus 30 forms two-color shearing fringes by arranging two light splitting means (diffraction gratings) 32 and 36 in a conjugate manner and matching the orders of the two diffracted lights, thereby forming the test optical system 18. Measure the wavefront aberration. Reference numeral 34 denotes a first mask, and reference numeral 38 denotes a second mask. As the mask 34, a pair of windows 34a and 34b aligned in the X direction and the Y direction, respectively, are used interchangeably. The mask 36 has a window 36a.

  Since the measurement accuracy of the DLSI is directly affected by the manufacturing accuracy of the diffraction grating, it is greatly affected by the patterning error described with reference to FIG. In particular, since the light splitting means 32 and 36 are arranged in a conjugate manner, the light splitting means 36 on the image plane side has a smaller pitch, and the effect of stitching error is increased accordingly. Therefore, the measuring apparatus 30 performs the measurement a plurality of times by shifting the light dividing means 36 in the pattern line direction (X direction), and takes the average as in FIG. As in the case of PDI, it is desirable to set the shift amount to a value that is equal to or larger than the screen size of the electron optical system of the electron beam drawing apparatus.

  The accuracy required for wavefront measurement of the EUV projection optical system is 0.1 nm or less, and a value of λ / 100 or less is required considering a wavelength of 13.5 nm. In order to perform such high-accuracy measurement, it is necessary to compensate for any imperfections of the constituent optical elements. In particular, in an EUV interferometer with few constituent elements, it is most important to eliminate errors in the elements themselves. According to the present embodiment, it is possible to correct the patterning error generated by the light splitting means and measure the wavefront aberration of the optical system 18 to be measured with high accuracy.

  Hereinafter, an exposure apparatus 40 according to another embodiment of the present invention will be described with reference to FIG. Here, FIG. 7 is a schematic block diagram of an exposure apparatus 40 that uses EUV light as exposure light. However, the exposure apparatus of the present invention is not limited to EUV light.

  The present invention is applicable not only to the DLSI method but also to other shearing interference such as Talbot interference. Needless to say, the present invention is applicable to LDI (Line Diffraction Interference) interference in addition to PDI interference.

  In FIG. 7, reference numeral 41 denotes an illumination system including a light source, 42 denotes a reticle stage, 44 denotes a reticle, the reticle 44 may be the first mask 12, or a semiconductor device (a semiconductor chip such as an IC or LSI, or a liquid crystal panel or CCD). Or the like) (a pinhole 12a is necessary in this case). Reference numeral 18A denotes a projection optical system, which is a test optical system, 45 denotes a wafer stage, 14A denotes a diffraction grating (light splitting means), which is on the wafer stage 45 side in FIG. 7, but may be arranged on the reticle stage 42 side. The diffraction grating 14A has the same structure as the diffraction grating 14 shown in FIG. 2, and has two patterns in which the directions of the gratings are orthogonal. Reference numeral 46 denotes a pattern surface on which the pinhole 20a and the window 20b are arranged, 26 denotes a detection unit, and 47 denotes an object to be exposed (wafer in the present embodiment). The pattern surface 46 and the detection unit 26 have an integral structure and are disposed on the wafer stage 45.

  With the configuration as described above, similarly to FIG. 1, the illumination system 41 illuminates the mask 44, and a wavefront that is spherical in only one direction emitted from the pinhole 12a is reflected by the diffraction grating 14A via the projection optical system 18A. The light is divided, and the zero-order light is incident on the pinhole 20a of the pattern 46 and the first-order diffracted light is incident on the window 20b. Since the interference fringes have TLT fringes corresponding to the separation angle of the 0th-order light and the primary light, the interference fringes obtained by the detection unit 26 are phased by the moire method using the control unit 28 (not shown). Get. Alternatively, the phase of the interference fringes is obtained by the phase shift method by scanning the diffractive optical element perpendicularly to the optical axis of the projection optical system 18 by scanning means (not shown). Further, the diffraction grating 14A is moved by the driving means 16, and aberration measurement is similarly performed at several points within the angle of view of the projection optical system 18, thereby measuring the aberration characteristics within the angle of view of the projection optical system. Similarly to FIG. 5, the driving means 16 shifts the diffraction grating 14A by a predetermined amount in the pattern line direction and performs measurement a plurality of times, so that the measurement accuracy is improved. In this embodiment, a reflection pattern is used as a mask so that an aberration measurement function can be easily added to the projection exposure apparatus.

  Hereinafter, an aberration correction method according to an embodiment of the present invention will be described. In the exposure apparatus 40, a plurality of optical elements (not shown) constituting the projection optical system are movable in the optical axis direction and / or the optical axis orthogonal direction, and according to the present embodiment, an aberration adjustment drive system (not shown) is used. By driving one or a plurality of optical elements based on the obtained aberration information, it is possible to correct or optimize one or more aberrations of the projection optical system. In addition to the movable lens, means for adjusting the aberration of the projection optical system 40 include a movable mirror (when the optical system is a catadioptric system or a mirror system), a parallel plane plate that can be tilted, and a pressure-controllable space. In addition, those using various known systems such as surface correction by an actuator can be applied.

  Next, a device manufacturing method using the projection exposure apparatus 40 will be described. FIG. 8 is a flowchart for explaining the manufacture of a semiconductor device (a semiconductor chip such as an IC or LSI, or a liquid crystal panel or a CCD). In step 1 (circuit design), a semiconductor device circuit is designed. In step 2 (mask production), a mask on which the designed circuit pattern is formed is produced. On the other hand, 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 prepared mask and wafer. The next step 5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer produced in step 4, and is a process such as an assembly process (dicing, bonding), a packaging process (chip encapsulation), or the like. including. In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. Through these steps, the semiconductor device is completed and shipped (step 7).

  FIG. 9 is a detailed flowchart of the wafer process in Step 4 of FIG. In step 11 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an insulating film is formed on the wafer surface. In step 13 (electrode formation), an electrode is formed on the wafer by vapor deposition or the like. In step 14 (ion implantation), ions are implanted into the wafer. In step 15 (resist process), a photosensitive material is applied to the wafer. Step 16 (exposure) uses the exposure apparatus 40 to expose the circuit pattern of the mask 42 onto the wafer 47. In step 17 (development), the exposed wafer 47 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 repeatedly performing these steps, multiple circuit patterns are formed on the wafer 47. If the manufacturing method of this embodiment is used, the highly accurate semiconductor device which was difficult to manufacture conventionally can be manufactured.

  Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the gist thereof. For example, the light splitting means may be a two-dimensional diffraction grating.

It is an optical path figure of the measuring device of one embodiment of the present invention. It is a schematic plan view of the light splitting means of the measuring apparatus shown in FIG. It is a schematic diagram for demonstrating the optical characteristic of the light division means shown in FIG. It is a schematic diagram for demonstrating the optical characteristic of the light division means shown in FIG. It is a flowchart for demonstrating the measuring method of one Embodiment of this invention. It is an optical path figure of the measuring device of another embodiment of the present invention. It is an optical path figure for demonstrating the exposure apparatus of one Embodiment of this invention. It is a flowchart for demonstrating manufacture of devices (semiconductor chips, such as IC and LSI, LCD, CCD, etc.). 9 is a detailed flowchart of the wafer process in Step 4 shown in FIG. 8.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 30 Measuring device 12 1st mask 14, 14A, 32, 36 Optical division means 18 Test optical system 20 2nd mask 12a, 20a Pinhole 20b Window 22 Stage 24 Driving means 26 Detection part 28 Control part 40 Exposure apparatus

Claims (10)

Using light splitting means configured by connecting a plurality of regions having aligned to arranged pattern line respectively dividing the light beam of the measurement light, by interfering the measurement light that has passed through the target optical system to obtain in the method to obtain Ru wavefront aberration of the target optical system interference fringes measured to be,
A step in each of a plurality of positions of different said light splitting means by moving said light splitting means by an amount greater than the size of the area in the direction in a direction parallel to the front Symbol pattern lines make measurements of the interference fringes,
Averaging the results of the plurality of measurements at the plurality of locations ;
Measurement wherein that having the steps Ru obtain the wavefront aberration on the basis of data obtained by the averaging. The measuring method according to claim 1, the said light splitting means is a diffraction grating, characterized in that. Each of the plurality of regions corresponds to the screen of the electron optical system of the electron beam exposure apparatus used to create the light splitting means, and the joining is performed by stitching the screen by the electron beam exposure apparatus. those were, measuring method according to claim 1, characterized in that. The measuring method according to claim 1 wherein the interference based on the point diffraction interferometry or ray diffraction interferometry, it is characterized. The measuring method according to claim 1 wherein the interference based on the shearing interferometry, it is characterized. A step Ru obtain the wavefront aberration measuring method using the target optical system according to claim 1,
Adjusting the test optical system based on the obtained wavefront aberration;
Exposure method characterized by having the steps of exposing an object using the adjusted for such has been the target optical system. A resulting Ru measuring device wavefront aberration of the target optical system by measuring the interference fringes obtained by interference measurement light passing through the target optical system,
In alignment with placement pattern line is constructed by connecting a plurality of regions each having a light splitter for splitting the light of the measuring light,
Drive means Before moving the light splitting means by an amount greater than the size of the area in the direction in a direction parallel to the front Symbol pattern line,
Measuring apparatus characterized by having a means that turn into averaging the results of the plurality of measurements at a plurality of positions of different said light splitting means by the movement by the drive means. An exposure apparatus having a projection optical system and exposing an object to be exposed with exposure light through a mask and the projection optical system ,
The pre SL projection optical system having a measuring device according to claim 7, the optical system, an exposure apparatus, characterized in that. The exposure light is less extreme ultraviolet wavelength 20 nm, the exposure apparatus according to claim 8, characterized in that. Comprising the steps of exposing an object using an exposure apparatus according to claim 8,
Device manufacturing method and a step of developing the exposed object that has been exposed in the step.