WO2003067182A1 - Procede de mesure d'interference differentielle et interferometre differentiel, procede de production d'un systeme optique de projection, systeme optique de projection, et systeme d'exposition par projection - Google Patents

Procede de mesure d'interference differentielle et interferometre differentiel, procede de production d'un systeme optique de projection, systeme optique de projection, et systeme d'exposition par projection Download PDF

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Publication number
WO2003067182A1
WO2003067182A1 PCT/JP2003/000897 JP0300897W WO03067182A1 WO 2003067182 A1 WO2003067182 A1 WO 2003067182A1 JP 0300897 W JP0300897 W JP 0300897W WO 03067182 A1 WO03067182 A1 WO 03067182A1
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WIPO (PCT)
Prior art keywords
light
optical system
shearing interferometer
light beam
light beams
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PCT/JP2003/000897
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English (en)
Japanese (ja)
Inventor
Zhigiang Liu
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Nikon Corporation
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Application filed by Nikon Corporation filed Critical Nikon Corporation
Priority to AU2003244344A priority Critical patent/AU2003244344A1/en
Publication of WO2003067182A1 publication Critical patent/WO2003067182A1/fr

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/70591—Testing optical components
    • G03F7/706—Aberration measurement
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02097—Self-interferometers
    • G01B9/02098—Shearing interferometers

Definitions

  • the present invention relates to a shearing interference measuring method and a shearing interferometer, a method of manufacturing a projection optical system, a projection optical system, and a method of manufacturing a projection optical system. , And a projection exposure apparatus.
  • FIG. 14 is a diagram showing a conventional shearing interferometer.
  • Fig. 14 (a) shows a shearing interferometer that measures the transmitted wavefront of the test object (here, the projection optical system PL), and
  • Fig. 14 (b) shows the wavefront of the return light from the test object (here, the PL).
  • a shearing interferometer for measuring the reflected wavefront of the test surface 4 shows a shearing interferometer for measuring the reflected wavefront of the test surface 4).
  • a measurement light beam L (a spherical wave diverging from one point of a reticle surface R, which is an object surface) is made incident on an optical system PL to be inspected, and the optical system PL is subjected to measurement.
  • the measurement light beam L emitted from the light analysis system PL is split into two light beams L 1 and L 2 whose wavefronts are shifted from each other by the diffractive optical element 2, and the interference fringes due to the light beams L 1 and L 2 are captured by the CCD camera 3. Observed by such as. From this interference fringe, the shape of the transmitted wavefront of the test optical system PL is determined.
  • the measurement light beam L (a light beam that is incident substantially perpendicularly to the test surface 4) is incident on the test surface 4, and the measurement light beam L is incident on the test surface 4.
  • the reflected measurement light beam L is split by a half mirror HM2 etc. into two light beams L l and L 2 (not shown) whose wavefronts are shifted from each other, and the interference fringes caused by these light beams LI and L 2 are observed by a CCD camera 3 etc. Is what you do. From this interference fringe, the shape of the reflected wavefront of the test surface 4 is determined.
  • the two light beams branched from the same light source interfere without shifting the wavefront, so the wavefront (hereinafter referred to as the “noise wavefront”) that indicates the disturbance and aberration on the light source side superimposed on the wavefronts of the two light beams, respectively
  • the interference fringes generated by the overlap between the two light beams and the phase difference distribution between the wavefronts of the two light beams are not affected by the noise wavefront.
  • two light beams (light beams L 1 and L 2 in Fig. 14) branched from the same light source interfere with each other by shifting their wavefronts. And affect the interference fringes. Disclosure of ⁇
  • An object of the present invention is to provide a shearing interferometer and a shearing interferometer capable of performing measurement without being affected by disturbance or aberration on the light source side.
  • Another object of the present invention is to provide a method of manufacturing a high-performance projection optical system by applying the shearing interference measurement method.
  • Another object of the present invention is to provide a high-performance projection optical system.
  • Another object of the present invention is to provide a high-performance projection exposure apparatus.
  • the measurement light beam emitted from the light source is divided to generate two light beams having wavefronts shifted from each other, and the two light beams are applied to the test object with the wavefronts shifted. Light is projected, and interference fringes occurring at positions where the wavefronts of the two light beams passing through the test object overlap are detected.
  • the interference fringes formed by the two light beams at that position are affected by the transmitted wavefront (signal wavefront) corresponding to the aberration of the test object, but are not affected by disturbance or aberration on the light source side. Therefore, according to this shearing interference measurement method, measurement can be performed without being affected by disturbance or aberration on the light source side.
  • a phase shift interferometry for detecting the interference fringes a plurality of times while shifting the phase of the two light beams is applied.
  • measurement accuracy can be improved.
  • the shearing interferometer of the present invention is arranged in the optical path of the measurement light beam emitted from the light source, and divides the measurement light beam to generate two light beams having different wavefronts.
  • the arrangement position of the detector is a position conjugate with the division plane of the division optical system.
  • the optical path of the two light beams that passes through the test object and enters the detector is divided into two light beams, and the wavefronts of the two light beams are placed on the detector. Are arranged.
  • the splitting optical system for splitting the measurement light beam and the splitting optical system for splitting the two light beams have a conjugate relationship.
  • a mask for cutting light other than the two light beams whose wavefronts overlap on the detector is arranged in the optical path of the two light beams. In this way, measurement accuracy can be improved.
  • the split optical system comprises a diffractive optical element.
  • the shearing interferometer of the present invention is arranged in the optical path of the measurement light beam emitted from the light source, and divides the measurement light beam to generate two light beams whose wavefronts are deviated from each other, and combines the two light beams.
  • the splitting optical system includes: a beam splitter that splits the measurement light beam into two light beams of a transmitted light beam and a reflected light beam; and the two light beams split by the beam splitter.
  • a polarization beam splitter is used in the beam splitter, and a polarization beam splitter is used between the split optical system and the detector.
  • a polarizing plate is arranged in the optical path of the two light beams. In this way, measurement accuracy can be improved.
  • the position of the detector is a position conjugate with the surface of the test object.
  • a mask for cutting light other than the two light beams whose wavefronts overlap on the detector is arranged in the optical path of the two light beams. In this way, measurement accuracy can be improved.
  • a method of manufacturing a projection optical system according to the present invention includes a procedure for inspecting a part or all of the projection optical system by the shearing interference measurement method of the present invention. Since the shearing interference measurement method of the present invention can perform high-accuracy measurement, the inspection is performed with high accuracy. Therefore, according to the method for manufacturing a projection optical system of the present invention, a high-performance projection optical system can be manufactured.
  • a projection optical system according to the present invention is manufactured by the method for manufacturing a projection optical system according to the present invention. Such a projection optical system has high performance.
  • a projection exposure apparatus of the present invention includes the projection optical system of the present invention. Such a projection exposure apparatus has high performance.
  • FIG. 1A is a configuration diagram of the shearing interferometer of the first embodiment
  • FIG. 1B is a diagram illustrating an alignment method of the shearing interferometer of the first embodiment.
  • FIG. 2 is a diagram showing a modified example of the shearing interferometer of the first embodiment.
  • FIG. 3A is a configuration diagram of the shearing interferometer of the second embodiment
  • FIG. 3B is a diagram illustrating an alignment method of the shearing interferometer of the second embodiment.
  • FIG. 4 is a diagram illustrating the shearing interferometer of the second embodiment in which the imaging surface of the CCD camera 3 and the diffractive optical element G21 are in a conjugate relationship.
  • FIG. 5 is a diagram showing a modified example of the shearing interferometer of the second embodiment.
  • FIG. 6A is a configuration diagram of the shearing interferometer of the third embodiment.
  • FIG. 6 (b) is a diagram showing the optical paths 1 ⁇ 1, R2 of the light beams L1, 2 of this shearing interferometer.
  • FIG. 7 is a diagram illustrating an application example of the shearing interferometer of the third embodiment.
  • FIG. 8 is a diagram showing a modified example of the shearing interferometer of the third embodiment.
  • FIG. 9A is a configuration diagram of the shearing interferometer of the fourth embodiment.
  • FIG. 9B is a diagram showing the optical paths 11 and R2 of the light beams L1 and L2 of the shearing interferometer.
  • FIG. 10 is a diagram illustrating a modified example of the shearing interferometer of the fourth embodiment.
  • FIG. 1.1 is a configuration diagram of the shearing interferometer of the fifth embodiment.
  • FIG. 12 is a configuration diagram of the shearing interferometer of the sixth embodiment.
  • FIG. 13 is a schematic configuration diagram of the projection exposure apparatus of the seventh embodiment.
  • FIG. 14 is a diagram showing a conventional shearing interferometer. Sun ⁇ ⁇
  • a shearing interferometer of the present invention of a type for measuring a transmitted wavefront of a test object and a shearing interferometer thereof will be described.
  • FIG. 1A is a configuration diagram of the shearing interferometer of the present embodiment.
  • test object is the projection optical system P L (for example, EUVL) of the projection exposure apparatus, but the present invention can be applied to other test objects.
  • P L for example, EUVL
  • a measurement light beam (hereinafter, referred to as a spherical wave diverging from one point of the reticle surface R) enters the projection optical system PL from the reticle surface R side.
  • a detector such as a CCD camera 3 is arranged on the wafer surface W side of the projection optical system PL.
  • the measurement light beam L is generated by collecting a light beam emitted from a light source (not shown) on the reticle surface R.
  • a split optical element for example, a diffractive optical element G11
  • a diffractive optical element G11 is included in the measurement light beam L on the reticle surface R side. ) Is inserted.
  • the insertion position of the diffractive optical element Gl1 is determined by the focusing position of the measurement light beam L (L The light source side is closer to the tickle surface R).
  • the diffractive optical element Gl1 divides the measurement light beam L to generate two light beams L1 and L2 whose wavefronts are shifted from each other.
  • the 0th-order diffracted light and the 1st-order diffracted light generated in the diffractive optical element G11 are used as the light flux L1 and the light flux L2, respectively.
  • the wavefront of the light beam L1 and the wavefront of the light beam L2 are shifted in the horizontal direction (object height direction), and the light-collecting positions of both light beams are shifted from each other on the reticle surface R. was shown.
  • the most efficient cut can be made when it is placed near the focal point (here, near the reticle surface R).
  • this mask M11 has openings at the light-condensing point of the light beam L1 and the light-condensing point of the light beam L2, respectively, and the other parts are light-shielded. It is a mask that became a department.
  • the light beam L1 and the light beam L2 that have passed through the mask M11 and then have passed through the projection optical system PL are condensed on the wafer surface W (at positions shifted from each other).
  • the imaging surface of the CCD camera 3 of the present embodiment is arranged at a position conjugate with (the diffraction surface of) the diffraction optical element G11 with respect to the projection optical system PL.
  • the shearing interference measurement of the present embodiment based on the output of the CCD camera 3, the shear direction and the shear amount from the measurement light beam L to the light beams Ll and L.2, it corresponds to the aberration of the projection optical system PL. Calculate the transmitted wavefront.
  • the shear amount and shear direction can be obtained from the design data of the shearing interferometer and the data measured by the shearing interferometer.
  • the same noise wavefront is superimposed on the wavefront of the light beam L1 and the wavefront of the light beam L2 obtained by dividing the measurement light beam L.
  • the noise wavefront superimposed on the wavefront of the light flux 1 The noise wavefront superimposed on the wavefront of the light beam L2 just overlaps, and the phase difference between the noise wavefronts is almost zero.
  • the light beam L1 and the light beam L2 enter the projection optical system PL with their wavefronts shifted from each other, the transmission corresponding to the aberration information of the projection optical system PL superimposed on the light beam L1
  • the wavefront (signal wavefront) and the signal wavefront superimposed on the light beam L2 are shifted from each other at the position, and a phase difference distribution is generated.
  • the interference fringes formed by the light beam L1 and the light beam L2 on the imaging surface of the CCD camera 3 arranged at that position are affected by the transmitted wavefront (signal wavefront) corresponding to the aberration of the projection optical system PL. On the other hand, it is not affected by the noise wavefront.
  • FIG. 1B is a diagram illustrating an alignment method of the shearing interferometer of the present embodiment.
  • the conjugate relationship is set based on whether or not the light flux L1 and the light flux L2 are substantially overlapped on the imaging surface of the CCD camera 3.
  • a target T that partially blocks the measurement light L is placed in the measurement light L incident on the diffractive optical element Gl1, and one of the light L1 and the light L2 is shielded.
  • One of the openings of the mask M11 is shielded from light.
  • the target T is disposed at a position as close as possible to the diffractive optical element G11.
  • the opening of the mask M11 is arranged only at one of the light-condensing points of the light beam L1 and the light beam L2, and the other light-condensing portion
  • the mask M11 may be shifted in the reticle plane R so that the light shielding portion of the mask M11 is arranged at a point.
  • one of the light flux L 1 and the light flux L 2 is provided on the imaging surface of the CCD camera 3. Only in the evening, an image of the gate T is formed.
  • the output of the CCD camera 3 is referred to while the other of the light beam L.l and the light beam L2 is shielded, and the position of the formation of the target T on the imaging surface is determined.
  • the positions of the diffractive optical element Gl1 and the CCD camera 3 are adjusted so as to be the same as the stored formation positions.
  • FIG. 2 is a diagram showing a modified example of the shearing interferometer of the first embodiment.
  • the position at which the diffractive optical element Gl1 is disposed is on the light source side with respect to the reticle surface R (see FIG. 1).
  • a diffractive optical element according to the present modification is indicated by reference numeral G 11 'in FIG.
  • the mask M 11 ′ for cutting off the extra light generated in the diffractive optical element G 11 may be arranged near the wafer surface W as shown in FIG. In this case as well, the CCD camera 3 is arranged at a position conjugate with (the diffraction surface of) the diffractive optical element G 11 ′ with respect to the projection optical system PL.
  • an evening shearing interferometer of the present invention for measuring a transmitted wavefront of a test object and a shearing interference method thereof will be described.
  • only the differences from the first embodiment will be described, and the description of the other parts will be omitted.
  • FIG. 3A is a configuration diagram of the shearing interferometer of the present embodiment.
  • the diffractive optical element as a split optical element is not only on the reticle surface R side of the projection optical system PL but also on the wafer surface W side. It is also located at the point.
  • a diffractive optical element as a nine-segment optical element is additionally arranged on the reticle surface R side of the projection optical system PL.
  • diffractive optical elements G 21 and G 22 are arranged on the reticle surface R side and the wafer surface W side, respectively.
  • the diffractive optical element G21 like the diffractive optical element G11 of the first embodiment, generates two light beams L1 and L2 whose wavefronts are shifted from each other.
  • the 0th-order diffracted light and the 1st-order diffracted light generated in the diffractive optical element G21 are used as the light flux Ll and the light flux L2, respectively.
  • the diffractive optical element G22 integrates the two light beams L1 and L2 emitted from the projection optical system PL with a displacement equivalent to that of the diffractive optical element G21 to form one light beam (reverse To do).
  • Such a diffractive optical element G22 is designed in advance according to the diffraction pattern of the diffractive optical element G11, the magnification of the projection optical system PL, the wavelength used, and the like.
  • the interference fringes formed by the light beam L1 and the light beam L2 at that position are affected by the transmitted wavefront (signal wavefront) corresponding to the aberration of the projection optical system PL, but are not affected by the noise wavefront.
  • the diffractive optical element G 22 (the diffractive surface thereof) is arranged at a position conjugate with the diffractive optical element G 21 (the diffractive surface thereof) with respect to the projection optical system PL. Since the focal point of the light beam L1 and the focal point of the light beam L2 coincide on the wafer surface W, the wavefront of the light beam L1 and the wavefront of the light beam L2 can travel in the same direction. The interference fringes can be made almost one color.
  • the closer to one color ie, the larger the fringe interval of the interference fringes
  • the imaging surface of the CCD camera 3 can be arranged, for example, at a position conjugate with the pupil of the projection optical system PL, and the evaluation of the projection optical system PL based on the observed interference fringes can be facilitated.
  • the extra light generated by the diffractive optical element G 21 is cut by the mask M 21 arranged on the reticle surface R, and the diffractive optical element G 2
  • the extra light generated in 2 is cut by the mask M22 arranged on the wafer surface W surface.
  • the light beam L1 and the light beam L2 emitted from the diffractive optical element G22 are condensed at the same point, so that the mask M22 may have only one opening.
  • FIG. 3B is a diagram for explaining an alignment method of the shearing interferometer of the present embodiment.
  • This alignment method is the same as the alignment method of the shearing interferometer of the first embodiment, except that the position adjustment target is the diffractive optical element G21 and the diffractive optical element G22.
  • a sunset T which partially blocks the measurement light beam L is arranged, and at the same time, the light beams L 1 and L 2 One of the openings of the mask M21 is shielded so as to shield one of the openings.
  • the target T is disposed at a position as close as possible to the diffractive optical element G21.
  • the opening of the mask M21 is arranged only at one of the light-condensing points of the light beam L1 and the light beam L2, and the other light-condensing point To
  • the mask M21 may be shifted in the reticle plane R plane so that the light shielding portion of the mask M21 is arranged.
  • the position where the image of the target T is formed on the imaging surface is stored from the output of the CCD camera 3 at this time.
  • the output of the CCD camera 3 is referred to, and the formation position of the sunset T on the imaging surface is determined.
  • the positions of the diffractive optical element G21 and the diffractive optical element G22 are adjusted so that is the same as the stored formation position.
  • FIG. 4 shows that the diffractive optical element G21 and the diffractive optical element G22 are non-conjugated in the shearing interferometer of the present embodiment, and instead, the imaging surface of the CCD camera 3 and the diffractive optical element G21
  • FIG. 4 is a diagram showing a case where a diffraction surface (a diffraction surface) is set to a conjugate relationship.
  • the diffractive optical element G21 and the diffractive optical element G22 are not set to a conjugate relationship, if the imaging surface of the CCD camera 3 and the (diffractive surface of) the diffractive optical element G21 are set to a conjugate relation, The noise wavefront superimposed on the wavefront of the light beam L1 and the noise wavefront superimposed on the wavefront of the light beam L2 overlap on the imaging surface of the CCD camera 3.
  • the alignment may be performed by setting the position adjustment target to the diffractive optical element G21 or the CCD camera 3 in the above-described alignment method (see FIG. 3B).
  • FIG. 5 is a diagram showing a modified example of the shearing interferometer of the second embodiment.
  • shearing interferometer of the second embodiment can be modified.
  • the direction of deviation between the wavefront of the light beam 1 and the wavefront of the light beam L2 is referred to as the “lateral direction” (object height direction).
  • the term “wavefront direction” (direction along the wavefront) is used. Therefore, a diffractive optical element G 21, and a diffractive optical element G 22 ′ are provided between the diffractive optical element G 21 and the reticle surface R and between the diffractive optical element G 22 and the wafer surface W, respectively. Inserted.
  • the diffractive optical element G 21 ′ is designed in advance so that the focal points of the light beam L 1 and the light beam L 2 emitted from the diffractive optical element G 21 coincide.
  • the diffractive optical element G22 ' is designed in advance so that the converging points of the light beam L1 and the light beam L2 emitted from the diffractive optical element G22 coincide.
  • the interference fringes are detected while shifting at least one of the diffractive optical elements in the same direction as the wavefront dividing direction (that is, if the phase shift interferometry is applied, )
  • the measurement accuracy can be further improved.
  • a refraction member as an optical element of a shearing interferometer (because a refraction member that transmits a special wavelength).
  • a diffractive optical element was used as the split optical element.
  • a lens may be used for a part or all of the split optical element for a test object that can use a refraction member.
  • the direction of division of the light fluxes L 1 and L 2 is “horizontal direction” or “wavefront direction”, but may be the optical axis direction (vertical direction).
  • FIG. 6 A third embodiment of the present invention will be described based on FIGS. 6, 7, and 8.
  • FIG. 6 A third embodiment of the present invention will be described based on FIGS. 6, 7, and 8.
  • FIG. 6A is a configuration diagram of the shearing interferometer of the present embodiment.
  • FIG. 6B is a diagram showing the optical paths R 1 and R 2 of the light beams L 1 and L 2 of the shearing interferometer.
  • the shearing interferometer has a light source 5 such as a laser that emits a measurement light beam L to be incident on the surface 4 to be measured, and the measurement light beam L is divided before being incident on the surface 4 to be measured.
  • the split optical system 34 generates two shifted light beams L 1 and L 2 and projects them on the test surface 4 with the wavefront shifted, and returns to the split optical system 34 after being reflected by the test surface 4.
  • a CCD camera 3 for detecting interference fringes caused by the light beams L 1 and L 2 is provided.
  • Reference numeral 6 denotes a beam spreader that converts the measurement light beam L emitted from the light source 5 into a parallel light beam.
  • Reference numeral HM33 denotes a half mirror for guiding the light beams L 1 and L 2 reciprocating in the split optical system 3 in the direction of the CCD force camera 3.
  • Reference numeral 7 denotes an imaging optical system that forms an image of a light beam (light beam 1, L 2) incident on the CCD camera 3.
  • test surface 4 and the imaging surface of the CCD camera 3 are in a conjugate relationship via the split optical system 34, the half mirror HM33, and the imaging optical system 7.
  • test surface 4 and the imaging surface of the CCD camera 3 have a conjugate relationship via an optical system disposed therebetween.
  • the split optical system 34 is composed of two beam splitters P 34-1 and P 34-2, and mirrors M 34-1 and 34-2.
  • the measurement light beam L is split into a transmitted light beam and a reflected light beam (hereinafter, the transmitted light beam is referred to as a light beam L1 and the reflected light beam is referred to as a light beam L2) at a beam splitter P34-2.
  • the light beam L1 is reflected by the mirror M34-1 and is incident on the beam splitter P34-1, and the light beam L2 is reflected by the mirror M34-2 and is incident on the beam splitter P34-11.
  • the beam splitter P34-1 transmits the light flux L1 and emits the light to the surface 4 to be measured, and also reflects the light flux L2 and emits the light to the surface 4 to be measured.
  • the position of the mirror M 34-2 beam splitter P 34-1 is measured in a state where the light beams L 1 and L 2 are shifted from each other (in a state where the optical axis is shifted). Adjusted to be incident on surface 4.
  • the light beams L 1 and L 2 emitted from the splitting optical system 34 to the surface 4 to be detected and reflected on the surface 4 to be tested are transmitted through the splitting optical system 34 in the opposite direction, and then are transferred to the half mirror H M33 by the CCD. It is deflected in the direction of camera 3 and forms interference fringes on the imaging surface of CCD camera 3.
  • the shearing interference measurement based on the output of the CCD camera 3 and the shear direction and the shear amount from the measurement light beam L to the light beams Ll and L2, it corresponds to the unevenness of the surface 4 to be measured. Calculate the reflected wavefront.
  • the shear amount and shear direction can be obtained from the design data of the shearing interferometer and the data actually measured by the shearing interferometer.
  • the same noise wavefront is superimposed on the wavefront of the light beam L1 and the wavefront of the light beam L2 obtained by dividing the measurement light beam L.
  • the light beam L1 passing through the optical path R1 and the light beam L2 passing through the optical path R2 shown in FIG. 6 (b) reciprocate in a specific optical path in the split optical system. Therefore, the light beam L1 and the light beam L2 absorb the mutual wavefront shift (shift of the optical axis), and overlap each other after reciprocation (the optical path R1 is a half mirror HM33).
  • the luminous flux L 1 passing through the optical path R 1 and the luminous flux L 2 passing through the optical path R 2 are shifted from each other when they are incident on the surface 4 to be measured. Therefore, the reflected wavefront (signal wavefront) corresponding to the unevenness of the surface 4 to be measured, which is superimposed on the wavefront of the light beam L1, and the signal wavefront superimposed on the wavefront of the light beam L2, are the wavefront of the light beam L1.
  • the wavefront of the light beam L2 overlaps with the wavefront of the light beam L2, they deviate from each other.
  • the light is superimposed on the wavefront of the light beam L1
  • the reflected wavefront (signal wavefront) corresponding to the unevenness of the test surface 4 and the signal wavefront superimposed on the wavefront of the light beam L2 do not overlap, and generate interference fringes.
  • the interference fringes formed by the light flux L1 and the light flux L2 on the imaging surface of the CCD camera 3 are affected by the reflected wavefront (signal wavefront) corresponding to the unevenness of the surface 4 to be measured, while the noise wavefront is Not affected by
  • the beam splitter P 34 is used to increase the light amount of the light beam L 1 passing through the optical path R 1 and the light beam L 2 passing through the optical path R 2 to enhance the detection accuracy of interference fringes.
  • -Polarizing beam splitter is used as 1 or beam splitter P 34-2, and polarizing plate 35 is provided in front of CCD camera 3 (for example, between imaging optical system 7 and half mirror HM 33). Inserted.
  • the beam splitter P34_1 For example, if a polarizing beam splitter is used as the beam splitter P34_1, the P-polarized light of the light beam L1 transmitted through the beam splitter P34-2 is reflected on the surface 4 to be measured. Later, the light returns to the direction of the optical path R 1, and the S-polarized light of the light beam L 2 reflected by the beam splitter P 3 4 12 returns to the direction of the optical path R 2 after the reflection on the surface 4 to be measured.
  • a polarizing beam splitter is used as the beam splitter P34_1
  • the P-polarized light of the light beam L1 transmitted through the beam splitter P34-2 is reflected on the surface 4 to be measured. Later, the light returns to the direction of the optical path R 1, and the S-polarized light of the light beam L 2 reflected by the beam splitter P 3 4 12 returns to the direction of the optical path R 2 after the reflection on the surface 4 to be measured.
  • a polarization beam splitter is used for both the beam splitter P34-1 and the beam splitter P34-2.
  • the P-polarized light component of the measurement light beam L is surely set to the light beam L1 passing through the optical path R1, and the S-polarized light component of the measurement light beam L is surely changed to Since the light beam L2 can pass through the optical path R2, the loss of light amount can be suppressed.
  • phase shift interferometry is applied to the above-described shearing interference measurement, the measurement accuracy is further improved.
  • one or both of the mirror M34-1 and the mirror M34-2 may be slightly moved.
  • the moving direction is the direction in which the difference between the optical path lengths R 1 and R 2 of the light beams L 1 and L 2 changes (for example, the direction indicated by the arrow in FIG. 6A).
  • the output data of the CCD camera 3 (luminance distribution data of interference fringes) is sampled a plurality of times during this phase shift.
  • the calculation method is, for example, as follows.
  • the luminance distribution I of the interference fringes occurring on the imaging surface is
  • I 0 is the DC component of the luminance distribution of the interference fringes
  • A is the amplitude of the luminous flux LI
  • L 2 B i is the amplitude of various noises
  • i is the number of each interference fringe due to various noises.
  • N i is the phase distribution of the interference fringes due to each noise
  • 5 is the phase modulation by the phase shift of each interference fringe
  • T is the shape of the reflected wavefront (signal wavefront) corresponding to the unevenness of the surface 4 to be measured.
  • T (s) is a change in wavefront shape (unit: phase) due to shearing of the measurement light beam L into the light beam L1 or the light beam L2.
  • ⁇ f (i) is the sum of each i of f.
  • each luminance distribution data II, ... I8 are sampled while gradually shifting the phase by ⁇ / 2 as a phase shift
  • each luminance distribution data II, ... Is represented as
  • FIG. 7 is a diagram illustrating an application example of the shearing interferometer of the present embodiment. .
  • the object to be measured is a flat surface 4 to be measured, but a curved surface 4 ′ is measured by using a wavefront conversion element 38 as shown in A in FIG. You can also.
  • the folded reflecting surface 39 as shown in B in FIG. 7 not only the reflected wavefront of the test surface 4 but also the transmitted wavefront of the test object (such as the projection optical system PL) 4 ′′ can be measured. .
  • FIG. 8 is a diagram illustrating a modified example of the shearing interferometer of the present embodiment.
  • the split optical system 34 uses a half-mirror HM 33 instead of one of the beam splitters P 34-2.
  • the measurement accuracy is lower than in the case of using the polarizing beam splitter, but the number of parts of the shearing interferometer can be reduced because the half mirror HM33 can be used as well.
  • the present embodiment describes a shearing interferometer of the present invention of a type that measures the wavefront of the return light from the test object (the reflected wavefront of the test surface 4).
  • FIG. 9A is a configuration diagram of the shearing interferometer of the present embodiment.
  • FIG. 9 (b) is a diagram showing the optical paths 111 and R2 of the light beams L1 and L2 of this shearing interferometer.
  • the splitting optics 44 of this shearing interferometer consists of a single beam splitter P44 and a single mirror M44.
  • the reflection surface of the mirror M44 is arranged parallel to the reflection / transmission surface of the beam splitter P44.
  • the measurement light beam L is divided into a transmitted light beam and a reflected light beam (hereinafter, the transmitted light beam is referred to as a light beam L1 and the reflected light beam is referred to as L2) at a beam splitter P44.
  • the light beam L2 is projected onto the surface 4 to be measured as it is.
  • the light beam L1 is reflected by the mirror M44, then re-enters the beam splitter P44, passes through the beam splitter P44, and is projected on the surface 4 to be measured.
  • the positions of the mirror M44 and the beam splitter P44 are adjusted so that the light beams L1 and L2 enter the surface 4 to be measured with their wavefronts shifted from each other (with the optical axis shifted). Have been.
  • the light beams LI and L2 emitted from the splitting optical system 44 to the surface 4 to be measured and reflected on the surface 4 to be tested are transmitted to the half mirror 1 It is deflected in the direction of camera 3 and forms an interference fringe on the imaging surface of CCD camera 3.
  • the light beam L1 passing through the optical path R1 and the light beam L2 passing through the optical path R2 shown in FIG. 9 (b) reciprocate in a specific optical path in the splitting optical system 34. . Therefore, between the light beam L1 and the light beam L2, the mutual wavefront shift (shift of the optical axis) is absorbed, and the wavefront of the light beam L1 and the wavefront of the light beam L2 reciprocate.
  • the optical path of the HM33 is the optical path of the beam splitter P44 ⁇ the surface of the beam to be inspected 4 beam splitters, and the optical path of the half mirror HM33 is the optical path R2.
  • the interference fringes formed by the light flux L1 and the light flux L2 on the image plane of the CCD camera 3 correspond to the unevenness of the surface 4 to be measured. While being affected by the reflected wavefront (signal wavefront), it is not affected by the noise wavefront due to disturbances and aberrations on the light source side (beam expander 6, light source 5).
  • the beam splitter P44 is used as the beam splitter P44 in order to increase the light amount of the light flux L1 passing through the light path R1 and the light flux L2 passing through the light path R2 to increase the detection accuracy of interference fringes.
  • a polarizing beam splitter is used, and a polarizing plate 35 is inserted in front of the CCD camera 3 (for example, between the imaging optical system 7 and the half mirror HM 33).
  • phase shift interferometry for example, the method described in the third embodiment
  • the measurement accuracy is further improved.
  • one or both of the mirror M44 and the beam splitter P44 may be slightly moved.
  • the moving direction is a direction in which the difference between the optical path lengths 1 ⁇ 1 and R2 of the light fluxes L1 and L2 changes.
  • the shearing interferometer shown in FIG. 9 may be modified as shown in FIG. 10 and then the phase shift may be performed by another method.
  • the phase shift method described below can be similarly applied to the third, fifth, and sixth embodiments.
  • a quarter-wave plate 45 is inserted on the incident side of the polarizing plate 35, and the polarizing plate 35 is rotatable around the optical axis.
  • the main axis of the quarter-wave plate 45 is set to be 45 ° with respect to the P or S polarization direction of the light beams L 1 and L 2.
  • the light beam L 1 (linearly polarized light of P) and the light beam L 2 (of S (Linearly polarized light) is converted into circularly polarized light whose directions are opposite to each other.
  • the phase shift can be performed by rotating the polarizing plate 35.
  • a single split optical element 4 4 ′ having the mirror M 44 and the beam splitter P 44 fixed is used instead of the split optical system 44. You can also. .
  • shearing interferometer shown in FIG. 9 or FIG. 10 can also measure the curved test surface 4 ′ by using the wavefront conversion element 38 as shown in A in FIG.
  • the reflection surface 39 is used as shown in FIG. 7B, not only the reflection wavefront of the test surface 4 but also the transmission wavefront of the test object (such as the projection optical system PL) 4 "is measured. You can do that too.
  • the shearing interferometer according to the third embodiment and the shearing interferometer according to the fourth embodiment are of the type in which the shear direction is the horizontal direction. In the present embodiment, the case where the shear direction is the radial direction will be described.
  • FIG. 11 is a configuration diagram of the shearing interferometer of the present embodiment.
  • the splitting optical system 54 of this shearing interferometer is composed of a beam splitter P34-1 and a beam splitter (here, a half mirror) HM33, a mirror M34-1, and a mirror M34-2. , And beam expanders R 54-1 and R 54-2 having different magnifications from each other.
  • the measurement light beam L is divided into a transmitted light beam and a reflected light beam (hereinafter, the transmitted light beam is referred to as a light beam Ll and the reflected light beam is referred to as a light beam L2) by a half mirror HM33.
  • the light beam LI is reflected by the mirror M 34-1, and then enters the beam splitter P 34-1 via the beam expander R 54-1.
  • the light beam L 2 is reflected by the half mirror HM 33, then enters the mirror M 34-2 via the beam expander R 54-2, is reflected by the mirror M 34-2, and is reflected by the beam splitter 224. It is incident on P 3 4—1.
  • the beam splitter P 34-1 transmits the light beam L 1 and emits the light to the surface 4 to be measured, and also reflects the light beam L 2 and emits the light to the surface 4 to be measured.
  • the light beam L1 and the light beam L2 incident on the surface 4 to be inspected have the same optical axis, but the beam expanders R54-1 and R54-2. Since the magnifications are different, the luminous flux diameter is shifted.
  • the light beam L 1 reciprocating in the beam expander R 54-1 and the light beam L 2 reciprocating in the beam expander R 54-2 absorb the mutual wavefront deviation (beam diameter deviation) due to the reciprocation. After the round trip. The wavefronts of each other overlap.
  • the interference fringes formed by the light flux L1 and the light flux L2 on the image plane of the CCD camera 3 are reflected by the unevenness of the surface 4 to be measured. While being affected by the wavefront (signal wavefront), it is not affected by the noise wavefront due to disturbances and aberrations on the light source side (beam expander 6, light source 5).
  • the shearing interferometer according to the third embodiment and the shearing interferometer according to the fourth embodiment have a structure in which the shear is used to shift the optical axis, but a shearing interferometer in which the optical axis is inclined will be described. .
  • FIG. 12 is a configuration diagram of the shearing interferometer of the present embodiment.
  • the splitting optical system 64 of this shearing interferometer has a beam splitter (here, a half mirror) HM64 and a beam splitter similar to the splitting optical system 34 shown in FIG. Evening (here, half mirror) HM33, Mira M34-l, and Mirror M34-2 are arranged.
  • the postures of the mirror M34-2 and the half-mirror HM64 are adjusted so that the light beam L1 and the light beam L2 are incident on the surface 4 to be inspected with their optical axes inclined by 0. I have.
  • the polarizing beam splitter is used to separate the light beam L1 and the light beam L2). I used the evening ..). Accordingly, the polarizing plate 35 shown in FIG. 8 is unnecessary.
  • the light beam L1 and the light beam L2 that have entered the surface 4 to be inspected return to another optical path in the split optical system 64 while keeping the optical axis inclined, and enter the imaging optical system 7 and the CCD camera 3 in that order. .
  • the inclination of the optical axis of the light beam 1 and the light beam L 2 at the time of entering the test surface 4 not being absorbed back and forth division optical system 64 c is on the imaging surface
  • the noise wavefront superimposed on the wavefront of the light beam L1 and the noise wavefront superimposed on the wavefront of the light beam L2 just overlap, and the reflection corresponding to the unevenness of the surface 4 to be measured, which is superimposed on the light beam L1
  • the wavefront (signal wavefront) and the signal wavefront superimposed on the light beam L2 deviate from each other.
  • the interference fringes formed by the light flux L1 and the light flux L2 on the imaging surface are affected by the reflected wavefront (signal wavefront) corresponding to the unevenness of the test surface 4 but not by the noise wavefront. .
  • a mask M61 be disposed on the focal plane of the imaging optical system 7.
  • the direction in which the two openings are arranged is set so as to correspond to the above-described inclination direction of the optical axis. In this way, the light beams L 1 and L 2 individually transmit one of the two openings and the other, and form interference fringes on the imaging surface of the CCD camera 3.
  • interference fringes caused by the light beams L1 and L2 are detected with high accuracy without being affected by other light.
  • the division optical element diffractive optical element
  • the mask the mask having two openings
  • FIG. 13 is a schematic configuration diagram of the projection exposure apparatus of the present embodiment.
  • the whole or a part of the projection optical system PL mounted on the projection exposure apparatus is inspected at the time of its manufacture by the interference measurement according to any of the above embodiments.
  • At least one surface of the projection optical system PL and / or any part of the projection exposure apparatus are adjusted according to the measurement result.
  • the projection optical system PL and / or the projection exposure apparatus have high performance even if the adjustment method is the same as the conventional one.
  • the projection exposure apparatus includes a projection optical system PL, a wafer stage 108 for mounting a wafer w, a reticle stage 105 for mounting a reticle r, and a light source section 101 for supplying light to the reticle r. And so on.
  • a reticle r and a wafer w are arranged on the object plane and the image plane of the projection optical system PL, respectively.
  • the projection exposure apparatus has a stage control for controlling the position of the stage 108. Control 107 is provided.
  • the projection optical system PL has an alignment optical system applied to a scan type projection exposure apparatus.
  • the illumination optical system 102 has an alignment optical system 103 for adjusting the relative position between the reticle r and the wafer w.
  • reticle stage 105 can move reticle r in parallel with respect to surface 108 a of wafer stage 108.
  • the projection exposure apparatus is provided with a reticle exchange system 104 for exchanging and transporting the reticle r set on the reticle stage 105.
  • the reticle exchange system 104 has a stage driver (not shown) for relatively moving the reticle stage 105 with respect to the surface 10.8a of the wafer stage 108.
  • the projection exposure apparatus is also provided with a main control unit 109 which performs control relating to a series of processes “from alignment to exposure”.
  • a shearing interferometer and a shearing interferometer capable of performing measurement without being affected by disturbance or aberration on the light source side are realized.
  • a high-performance projection optical system manufacturing method, a high-performance projection optical system, and a high-performance projection exposure apparatus are realized by applying the shearing interference measurement method.
  • the present invention contributes to improvement of semiconductor manufacturing technology.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Instruments For Measurement Of Length By Optical Means (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Testing Of Optical Devices Or Fibers (AREA)
  • Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)

Abstract

L'invention concerne un procédé de mesure d'interférence différentielle permettant de mesurer les interférences sans que les mesures soient affectées par des perturbations et par une aberration sur un côté de source lumineuse. Ce système consiste: à diviser une sortie de flux lumineux à partir d'une source lumineuse, de sorte à produire deux flux lumineux dont les fronts d'onde sont déviés l'un par rapport à l'autre; à projeter ces deux flux lumineux à fronts d'onde déviés sur un sujet à examiner; et à détecter la frange d'interférences apparaissant à un endroit où les fronts d'onde des deux flux lumineux traversant le sujet à examiner se chevauchent.
PCT/JP2003/000897 2002-02-07 2003-01-30 Procede de mesure d'interference differentielle et interferometre differentiel, procede de production d'un systeme optique de projection, systeme optique de projection, et systeme d'exposition par projection WO2003067182A1 (fr)

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AU2003244344A AU2003244344A1 (en) 2002-02-07 2003-01-30 Shearing interference measuring method and shearing interferometer, production method of projection optical system, projection optical system, and projection exposure system

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JP2002030413 2002-02-07
JP2002-030413 2002-02-07
JP2002-221765 2002-07-30
JP2002221765A JP2003302205A (ja) 2002-02-07 2002-07-30 シアリング干渉測定方法及びシアリング干渉計、投影光学系の製造方法、投影光学系、及び投影露光装置

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US7508488B2 (en) 2004-10-13 2009-03-24 Carl Zeiss Smt Ag Projection exposure system and method of manufacturing a miniaturized device
CN102878935A (zh) * 2012-09-25 2013-01-16 东南大学 基于剪切散斑干涉的光学离面位移场测量装置及测量方法

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US7333175B2 (en) * 2004-09-13 2008-02-19 Asml Netherlands, B.V. Method and system for aligning a first and second marker
JP4769448B2 (ja) * 2004-10-08 2011-09-07 キヤノン株式会社 干渉計を備えた露光装置及びデバイス製造方法
JP4731951B2 (ja) * 2005-02-28 2011-07-27 キヤノン株式会社 干渉縞の解析方法及び装置、測定装置、露光装置及びデバイス製造方法
JP4904708B2 (ja) * 2005-03-23 2012-03-28 株式会社ニコン 波面収差測定方法、波面収差測定装置、投影露光装置、投影光学系の製造方法
JP2006303370A (ja) 2005-04-25 2006-11-02 Canon Inc 露光装置及びそれを用いたデバイス製造方法
US7518703B2 (en) * 2005-06-28 2009-04-14 Asml Netherlands B.V. Lithographic apparatus and method
JP5336890B2 (ja) * 2009-03-10 2013-11-06 キヤノン株式会社 計測装置、露光装置及びデバイス製造方法
WO2014088089A1 (fr) * 2012-12-06 2014-06-12 合同会社３Ｄｒａｇｏｎｓ Dispositif de mesure de forme tridimensionnelle, procédé d'acquisition d'image d'hologramme et procédé de mesure de forme tridimensionnelle
US11892292B2 (en) 2017-06-06 2024-02-06 RD Synergy Ltd. Methods and systems of holographic interferometry
US10725428B2 (en) * 2017-06-06 2020-07-28 RD Synergy Ltd. Methods and systems of holographic interferometry
EP3887757A4 (fr) 2018-10-30 2022-10-19 RD Synergy Ltd. Procédés et systèmes d'interférométrie holographique

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US7508488B2 (en) 2004-10-13 2009-03-24 Carl Zeiss Smt Ag Projection exposure system and method of manufacturing a miniaturized device
CN102878935A (zh) * 2012-09-25 2013-01-16 东南大学 基于剪切散斑干涉的光学离面位移场测量装置及测量方法

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