WO2003076872A1 - Procede de mesure de forme, dispositif de mesure d'interference, procede d'elaboration d'un systeme optique de projection et dispositif d'alignement - Google Patents

Procede de mesure de forme, dispositif de mesure d'interference, procede d'elaboration d'un systeme optique de projection et dispositif d'alignement Download PDF

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Publication number
WO2003076872A1
WO2003076872A1 PCT/JP2003/002842 JP0302842W WO03076872A1 WO 2003076872 A1 WO2003076872 A1 WO 2003076872A1 JP 0302842 W JP0302842 W JP 0302842W WO 03076872 A1 WO03076872 A1 WO 03076872A1
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WIPO (PCT)
Prior art keywords
optical system
wavefront
shape
measurement
null
Prior art date
Application number
PCT/JP2003/002842
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English (en)
Japanese (ja)
Inventor
Shigeru Nakayama
Original Assignee
Nikon Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Nikon Corporation filed Critical Nikon Corporation
Priority to AU2003213455A priority Critical patent/AU2003213455A1/en
Publication of WO2003076872A1 publication Critical patent/WO2003076872A1/fr

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Classifications

    • 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

Definitions

  • the present invention relates to a shape measuring method for measuring a test surface of an optical element such as a lens.
  • the present invention relates to an interferometer for measuring a surface shape.
  • the present invention relates to a method for manufacturing a projection optical system to which an interference measurement method is applied. Further, the present invention relates to a projection exposure apparatus provided with a projection optical system. Background art
  • An interferometer is used for surface shape measurement.
  • the interferometer makes a light beam from a surface to be detected interfere with a light beam having a predetermined wavefront, and observes the interference fringes.
  • the shape of the surface to be measured with respect to a predetermined wavefront can be obtained in units of the wavelength of light or less.
  • a Fizeau type interferometer in which many of the reference light path and the test light path are overlapped has high performance.
  • null element An optical element or an optical system that enters the optical path of the interferometer to generate such a light beam is generally called a “null element”.
  • a null element is designed to convert the measurement light beam (generally a parallel light beam) emitted from the interferometer into a light beam having a curved wavefront.
  • a Fizeau lens is often used.
  • the Fizenz lens has a final semi-transparent surface (the surface opposite to the light source when used). Null element whose final surface is used as Fizeau surface.
  • null optical system a null element in which a Fizeau surface is arranged on the non-final surface
  • Null optics have more design freedom than Fizeau lenses because they are less constrained and can be designed to reliably generate the desired null wavefront (here, an aspheric wave).
  • the shape of the Fizeau surface can be selected relatively freely, it is generally possible to provide a flat surface (a flat Fizeau) that is easy to manufacture.
  • An object of the present invention is to obtain, from measurement results obtained by interferometry using a null optical system, shape information of a single unit of a test surface without being affected by errors caused by the null optical system.
  • An object of the present invention is to provide a shape measuring method.
  • Another object of the present invention is to provide an interferometer capable of efficiently performing surface shape measurement.
  • Another object of the present invention is to provide a method for manufacturing a high-performance projection optical system and a high-performance projection exposure apparatus.
  • the wavefront conversion from the Fizeau surface to the final surface of the null optical system is performed by performing interference measurement on the test surface using a null optical system having the Fizeau surface arranged on the non-final surface.
  • the shape information of the surface to be inspected based on the part is acquired.
  • by performing interference measurement on the surface to be measured by using a transmission type zone plate designed such that the wavefront of the transmitted m-th order diffracted light generated when the measurement light beam is incident becomes equivalent to the design shape of the surface to be measured The shape information of the test surface based on the wavefront of the transmitted mth-order diffracted light is acquired.
  • the transmission information generated by the above-mentioned method is to obtain error information of the wavefront conversion unit with reference to the wavefront of the m-th order diffracted light. Then, by performing an arithmetic process based on each of the acquired information, shape information of the above-mentioned single surface of the test surface is obtained.
  • the order m of the transmitted diffraction light is 1 or 11. Since such transmitted diffracted light has higher intensity than transmitted diffracted light of other orders, it is possible to perform interference measurement with high accuracy.
  • the Fizeau surface of the null optical system is moved from the Fizeau surface to the final surface.
  • the shape information of the surface to be inspected is acquired with reference to the wavefront conversion unit.
  • the reflective zone plate designed so that the wavefront of the reflected diffracted light of a predetermined order generated when the measuring light beam enters through the null optical system is equivalent to the reflected wavefront in the design shape of the surface to be inspected is used as the null optical system.
  • the reflection is performed by using a calibration null optical system designed such that a wavefront of light generated at the time of incidence of the measurement light beam is incident on the reflection type zone plate at an angle of an opposite sign to the null optical system.
  • the wavefront shape information of the reflected diffracted light having the same order as the reflected diffracted light with respect to the calibration null optical system is acquired.
  • the error information of the wavefront conversion unit with respect to the calibration null optical system is obtained. Then, by performing an arithmetic process based on each of the acquired information, shape information of a single unit of the test surface is obtained.
  • the order of the reflected diffraction light is 1 or —1. Since such reflected diffraction light has higher intensity than reflected diffraction light of other orders, it is possible to perform interference measurement with high accuracy.
  • the shape information of a single aspherical surface can be obtained with high precision. You can get every time.
  • the interferometer according to the present invention includes an interferometer, a null optical system in which a Fizeau surface is arranged on a non-final surface, and a wavefront of the transmitted m-order diffracted light generated when the measurement light flux of the interferometer is incident.
  • a transmissive zone plate designed to be equivalent to the design shape of the surface; support means for supporting the surface to be measured so as to be detachable with respect to the measurement light beam; And a switching unit for reversing the irradiation direction of the measurement light beam, and a support device for supporting the transmission zone plate so that it can be inserted into and removed from the measurement light beam and can be turned upside down.
  • Another interferometer of the present invention includes an interferometer, a null optical system in which a Fizeau surface is arranged on a non-final surface, and a predetermined light beam generated when the measurement light beam of the interferometer is incident via the null optical system.
  • a reflective zone plate designed so that the wavefront of the reflected diffracted light of the order is equivalent to the reflected wavefront in the design shape of the test surface; and a support for supporting the test surface removably with respect to the measurement light beam.
  • the shape of any one of the test surfaces of the projection optical system is measured by the shape measuring method of the present invention, and the measured shape of the single test surface is measured.
  • the processing adjustment of a part or the whole of the projection optical system is performed according to.
  • the shape measuring method of the present invention since the shape information of the single surface of the test surface can be obtained with high accuracy, even if the processing adjustment method is the same as the conventional method, the shape information can be obtained with high accuracy. However, the performance of the projection optical system is improved.
  • a projection exposure apparatus includes a projection optical system manufactured by the method for manufacturing a projection optical system according to the present invention.
  • the projection optical system is improved in performance. Therefore, even if other components are the same as the conventional one, the projection exposure apparatus is improved by the performance of the projection optical system. Is also improved.
  • FIG. 1 is a configuration diagram of the interference measurement system 1 of the first embodiment.
  • FIG. 2 is a diagram illustrating a shape measuring procedure according to the first embodiment.
  • FIG. 3 is a diagram illustrating a modification of the first embodiment.
  • FIG. 4 is a configuration diagram of the interference measurement system 2 of the second embodiment.
  • FIG. 5 is a diagram illustrating a shape measurement procedure according to the third embodiment.
  • FIG. 6 is a diagram illustrating a shape measuring procedure according to the fourth embodiment.
  • FIG. 7 is a schematic configuration diagram of a projection exposure apparatus according to the fifth embodiment.
  • FIG. 1 is a configuration diagram of an interference measurement system 1 of the present embodiment.
  • the interferometer 1 includes a Fizeau-type interferometer 14, a null optical system 12, and the like.
  • the object to be measured is the aspheric surface 11 a of the object 11 to be measured.
  • the measurement light emitted from the interferometer 14 enters the aspheric surface 11a via the null optical system 12 and the aspheric surface 1
  • the interferometer 14, the null optical system 12, and the test object 11 are placed in such a position that the reflected light at 1 a returns to the interferometer 14 again via the null optical system 12.
  • Reference numeral 13 denotes a support member that supports the test object 11.
  • the interferometer 14 includes an illumination optical system 61, an observation optical system 62, a beam splitter (polarizing beam splitter) 64, a wave plate (1/4 wavelength plate) 65, and the like.
  • the illumination optical system 61 emits measurement light
  • the observation optical system 62 detects interference fringes formed by interference light (described later).
  • Beam splitter (Polarizing beam splitter) 6 4 The measurement light emitted from the illumination optical system 6 1 is guided to the null optical system 12 and is reflected by the Fizeau surface 12 aa (described later) in the null optical system 12 to occur.
  • the interference light generated by the reference light that has passed through the null optical system 12 and the test light that has been reflected by the test aspheric surface 11 a after being transmitted through the null optical system 12 and incident on the re-null optical system 12 is transmitted to the observation optical system 6.
  • the wave plate (1Z 4 wave plate) 65 is inserted into the optical path between the beam splitter 64 and the null optical system 12.
  • the illumination optical system 61 includes a light source (laser light source) 61 c and a beam expander 61 d for converting a light beam emitted from the light source 61 c into a parallel light beam.
  • the polarization direction of the measurement light emitted from the illumination optical system 61 is selected such that all of the measurement light is guided in the direction of the null optical system 12 in the beam splitter 64.
  • the observation optical system 62 includes a beam diameter conversion optical system 62 that converts the diameter of the light beam of the interference light emitted from the beam splitter 64, and a two-dimensional image detector 6 that images interference fringes caused by the interference light. 2c etc. are arranged.
  • the output of the two-dimensional image detector 62c is connected to a computer (not shown).
  • the computer is arranged to analyze the interference fringes (calculate the phase distribution of the interference fringes) and to drive each drive unit of the interference measurement system 1.
  • the beam diameter conversion optical system 62d also serves to form an image of the aspheric surface 11a to be inspected on the two-dimensional image detector 62c, and each of the beams on the aspheric surface 11a to be inspected.
  • the distortion is designed so that the points correspond exactly to each point on the two-dimensional image detector 62c.
  • phase shift interferometry (fringe scan interferometry) is applied to the interference measurement system 1.
  • the null optical system 12 (or the test object 11) can be slightly moved in the optical axis direction by a piezo element or the like (not shown), and the computer (not shown) uses the null optical system 12 (or the test object).
  • a predetermined arithmetic process based on the phase shift interferometry is performed on the interference fringes acquired from the two-dimensional image detector 62c while the specimen 11) is moving, thereby increasing the phase distribution of the interference fringes. Calculate to accuracy.
  • the null optical system 12 is formed by a null element having a Fizeau surface 12aa on a non-final surface.
  • the null optical system 12, which is a null element has a single interference fringe pattern due to the reflected light (test light) from the aspheric surface 11a to be tested and the reflected light (reference light) from the Fizeau surface 12aa. It is designed to be. In other words, it is designed so that the wavefront of the measurement light beam (which is a parallel light beam) is converted to form a wavefront equivalent to the design shape of the aspheric surface 11a to be measured at the position of the predetermined remote distance L1.
  • the system other than the Fizeau surface 12 a a in the null optical system 12 may be configured by any of a diffractive optical element, a refractive lens, and a combination of a diffractive optical element and a refractive lens. Further, the shape of the Fizeau surface 12 a a may be flat or spherical.
  • the null optical system 12 includes a planar Fizeau member 12a and a wavefront conversion lens 12b in order from the light source side.
  • the Fizeau surface 12 aa is a surface of the Fizeau member 12 a on the wavefront varying lens 12 b side.
  • a transmission zone plate 10 as shown in a circle in FIG. 1 is prepared in order to carry out a shape measurement procedure described later.
  • the transmission zone plate 10 is designed according to the design shape of the aspheric surface 11a to be inspected.
  • the transmitted first-order diffracted light generated when the measurement light beam (here, a parallel light beam) is made incident on the transmission zone plate 10 has a predetermined wavefront equivalent to the design shape of the aspheric surface 11a to be measured. It is located at the remote distance L2 (see Fig. 2 (b)).
  • the sign of the order of the diffracted light diffracted toward the side closer to the optical axis is taken as “positive”, and the sign of the order of the diffracted light diffracted toward the side farther from the optical axis is taken as “negative”.
  • FIG. 2 is a diagram illustrating a shape measurement procedure according to the present embodiment.
  • interference measurement is performed on the test aspheric surface 1 la using the null optical system 12, and the Fizeau surface 12 aa of the null optical system 12 is changed to the final surface 12 bb.
  • the shape information (phase distribution data of interference fringes) W1 of the aspheric surface 11a to be measured is acquired with reference to the wavefront conversion unit 12 '.
  • the test aspheric surface 11a is arranged at the position of the remote distance L1 with respect to the null optical system 12 and the interferometer 14 is driven in that state.
  • the interference fringes are detected, and the interference fringes are analyzed (by a computer (not shown)) to obtain the interference fringe phase distribution data W1.
  • a computer not shown
  • the aspheric surface 11a to be measured is interferometrically measured using the transmission zone plate 10 and the transmission + first-order diffracted light of the transmission zone plate 10 is measured.
  • the transmission zone plate 10 into the measurement beam of the interferometer, and
  • the aspheric surface 11a to be measured is placed at a position of a remote distance L2 with respect to the 10 diffraction plane 10a, and the interference fringes are detected by driving the interferometer in that state, and the interference fringes are detected.
  • the phase distribution data W2 of the interference fringes is obtained by the analysis. What is detected here is an interference fringe formed by the reflected wavefront on the test aspheric surface 11a and the wavefront (reference wavefront) of the 0th-order diffracted light reflected on the transmission zone plate 10.
  • a parallel light beam is perpendicularly incident on the diffraction surface 10a of the transmission zone plate 10.
  • the Fizeau surface 12aa in the null optical system 12 is interferometrically measured from the final surface 12bb using the transmission zone plate 10 and the transmission is performed.
  • Error information (phase distribution data of interference fringes) W3 of the wavefront conversion unit 12 'in the null optical system 12 is acquired with reference to the wavefront of the transmitted first-order diffracted light generated in the mold zone plate 10.
  • the same interferometer 14 as in the normal interferometer or another interferometer configured as a Fizeau type insert the transmissive zone plate 10 into the measurement light beam of the interferometer,
  • the null optical system 12 is arranged at a position at a remote distance L3 with respect to the diffraction surface 10a of the plate 10 with the diffraction surface 10a and the final surface 12 bb facing each other.
  • the interferometer is driven to detect interference fringes, and the interference fringes are analyzed to obtain phase distribution data W3 of the interference fringes. Note that what is detected here is that the reflected wavefront at the Fiso surface 12 aa and the reflected wavefront at the transmission zone plate 10 This is an interference fringe formed by the wavefront (reference wavefront) of the next-order diffracted light.
  • the shape information to be acquired in the present invention is a rotationally symmetric component of a surface shape error. Therefore, all of the phase distribution, shape error, wavefront error, and the like in this specification indicate only their rotationally symmetric components. Note that extracting only the rotational symmetric component from certain data is easily performed by a known method.
  • the acquired phase distribution data W1 includes the shape error ES of the test aspheric surface 11a, the wavefront error and the shape error (EF + EW) of the wavefront conversion unit 1 2 'in the null optical system 12. ) Is superimposed (EF is the shape error of the Fizeau surface 12aa, and EW is the transmitted wavefront error of the wavefront conversion lens 12b).
  • the phase distribution data W2 includes the shape error ES of the aspheric surface 11a to be measured, the reflection of the transmission zone plate 10, the wavefront error of the 0th-order diffracted light (reference wavefront error) EO, and the transmission zone plate 10 Transmission + wavefront error EA of first-order diffracted light is superimposed.
  • the phase distribution data W3 includes the wavefront error of the 0th-order diffracted light reflected from the transmission zone plate 10 (reference wavefront error) E 0, the wavefront error of the first-order diffracted light transmitted through the transmission zone plate 10 EB, and null
  • the wavefront error and the shape error (EF + EW) of the wavefront conversion unit 12 in the optical system 12 are superimposed.
  • shape error indicates phase distribution data corresponding to a deviation from the design shape of each element.
  • wavefront error indicates phase distribution data corresponding to a deviation of a wavefront formed from each element from a design wavefront shape.
  • Each phase distribution data Wl, W2, W3 is expressed by the following equation (1).
  • Wavefront errors EA and EB are error components due to errors in the surface shape of the pattern surface on the transmission zone plate 10, and errors due to in-plane variation errors in the depth (height) of the diffraction pattern. Components, and error components due to diffraction pattern coordinate errors.
  • the order of the phase distribution data W2 and the phase distribution data W3 is opposite to each other.
  • the error component EP due to the coordinate error of the diffraction pattern is superimposed on each other with the same opposite sign, and the error component EC due to other than the coordinate error (surface shape error, in-plane variation in pattern depth). are superimposed equally.
  • each of the phase distribution data Wl, W2, and W3 acquired in the shape measurement procedure is an actually measured value.
  • the value of the error component EP due to the coordinate error can be measured directly from the transmission zone plate 10 with sufficient accuracy (by a coordinate measuring machine or the like).
  • Equation (4) the values of Wl, W2, W3, and EP obtained as described above are substituted into Equation (4) to determine the shape error ES of the aspheric surface 11a to be measured. Confuse.
  • the first calibration interferometer (FIG. 2 (b)) and the second calibration interferometer (FIG. 2 (c)) use different reference light generating elements. Also, the same effect can be obtained if the difference in shape error between the reference light generating elements is known. However, in this case, equation (1) (and therefore equation (4)) takes this difference into account.
  • FIGS. 1 and 2 show an example in which the test aspheric surface 11a is a convex surface
  • the present embodiment can be similarly applied to a case where the test aspheric surface is a concave surface.
  • the transmission zone plate 20 in this case is designed so that the wavefront of the transmitted first-order diffracted light is equivalent to the design shape of the surface to be measured.
  • the transmission first-order diffracted light generated in the transmission zone plate 20 is used (FIG. 3 (b)), and in the second calibration interferometry, the transmission first-order diffracted light is generated in the transmission zone plate 20. Transmission + 1st order diffracted light is used (Fig. 3 (c)).
  • the test surface is replaced with the test aspheric surface, Needless to say, the surface may be a spherical surface.
  • the shape of the surface to be measured can be determined with higher accuracy by adding the third calibration interference measurement described below.
  • the shape information of the spherical surface to be measured is acquired based on the transmission zone plate.
  • the interval between 21 and the transmission zone plate is set wider than the interval shown in Fig. 3 (b), and the transmission + 1st-order diffracted light generated in the transmission zone plate 20 is almost perpendicular to the spherical surface to be measured and almost in phase. Make it incident.
  • the same spherical wavefront is formed both on the side closer to and farther from the diffraction surface than the focal point. It is.
  • the error component EP due to the coordinate error can be eliminated by calculation.
  • the shape error ES of the spherical surface to be measured is extracted with higher accuracy without being affected by the error due to the measurement.
  • FIG. 4 is a configuration diagram of the interference measurement system 2 of the present embodiment.
  • the same elements as those shown in FIG. 1 are denoted by the same reference numerals.
  • the interference measurement system 2 is for efficiently performing the shape measurement described in the first embodiment.
  • the interference measurement system 2 includes an interference measurement device 24 in which an interferometer 14, a null optical system 12, and a test object 11 are arranged, and a computer 29.
  • the computer 29 is a control board that drives and controls each drive unit of the interference measurement device 24 It is a general-purpose computer or the like equipped with the (control circuit 29c), and has at least a CPU 29a and a memory 29b.
  • the transmission zone plate 10, the specimen 11, and the null optical system 12 can be moved to and from the measurement position (measurement optical path) by the optical arrangement mechanism 27, and Switching is possible.
  • the direction of incidence of the measurement light emitted from the interferometer 14 to the measurement position (measurement optical path) is as follows: a half mirror 25a, a total reflection mirror 25b, 25c, 25d, a shirt 26a, 26b, and It can be inverted by the optical path switching mechanism 28.
  • the measurement light emitted from the interferometer 14 is split into a first optical path R1 and a second optical path R2 by a half mirror 25a.
  • shirts 26a and 26b are provided so as to be detachable from each other.
  • the measuring light incident on the first optical path R1 deflects the optical path by 90 ° at the mirror 25b, and the measuring light incident on the second optical path R2 shifts the optical path by 90 ° at the mirrors 25c and 25d. To deflect.
  • the first light path R 1, ie, the measurement light passing through the mirror 25 b, and the second light path R 2, ie, the measurement light passing through the mirrors 25 c and 25 d, are at the same measurement position (measurement light path). , Incident from opposite sides.
  • FIG. 4 shows a state in which the shirt 26a is set to the open state, the shirt 26b is set to the closed state, and the first optical path R1 is valid.
  • the optical arrangement mechanism 27 has a support member that individually supports each of the transmission zone plate 10, the test object 11, and the null optical system 12, and a motor that individually drives each support member.
  • Each motor is connected to a control circuit 29c in the computer 29, and moves the support member according to an instruction from the CPU 29a in the computer 29. Then, each of the transmission zone plate 10, the test object 11, and the null optical system 12 is individually moved out of the measurement position (measurement optical path).
  • the optical arrangement mechanism 27 adjusts the distance between the optical elements (transmissive zone plate 10, test object 11, and null optical system 12) inserted at the measurement position (measurement optical path). Can be. Further, the optical arrangement mechanism 27 can also reverse the arrangement direction of the transmission zone plate 10.
  • the computer 29 operates as follows to execute the shape measuring procedure of the first embodiment.
  • the CPU 29a sets the shirt 26a to the open state and the shirt 26b to the closed state to enable the first optical path R1. .
  • the CPU 29a is positioned at a measurement position (measurement optical path) in order from the side where measurement light is incident, and in a disposition direction in which the final surface 12 bb and the aspheric surface 11a to be measured face each other.
  • the optical system 12 and the object 11 are inserted.
  • the CPU 29a drives the interferometer 14 to detect the interference fringes, and obtains the phase distribution data W1 of the interference fringes by analyzing the interference fringes.
  • the CPU 29a sets the shirt 26a to the open state and the shirt 26b to the closed state to enable the first optical path R1. I do.
  • the CPU 29a transmits light to the measurement position (measurement optical path) in order from the side where the measurement light is incident, and in the arrangement direction where the diffraction surface 10a and the aspheric surface 11a to be measured face each other. Insert the mold zone plate .10 and the specimen 11.
  • the CPU 29a drives the interferometer 14 to detect interference fringes, and analyzes the interference fringes to obtain phase distribution data W2 of the interference fringes.
  • the CPU 29a sets the shirt 26b to the open state and the shirt 26a to the closed state to enable the second optical path R2. I do.
  • the CPU 29a moves the transmission zone plate to the measurement position (measurement optical path) in order from the side where the measurement light is incident, and in the arrangement direction where the diffraction surface 10a and the final surface 12bb face each other. Insert 10 and null optics 1 2.
  • the CPU 29a drives the interferometer 14 to detect interference fringes, and obtains phase distribution data W3 of the interference fringes by analyzing the interference fringes.
  • the CPU 29a substitutes the values of W1, W2, and W3 obtained as described above into Expression (4) as described in the first embodiment, thereby obtaining the aspheric surface to be inspected.
  • 1 Acquire the shape information of the simple substance of 1a.
  • EP error component due to coordinate error
  • each optical element when performing the same shape measurement procedure as in the first embodiment, is made to be able to move away from the measurement light beam, and the arrangement direction of the transmission zone plate 10 is reversed.
  • a single interferometer 14 By making it possible and reversing the direction of incidence of the measurement light, a single interferometer 14 can be used.
  • shape measurement similar to that of the first embodiment can be efficiently performed.
  • the computer 29 (CPU) is set so that the normal interference measurement (FIG. 2 (a)) and the second calibration interference measurement (FIG. 2 (c)) are continuously performed. If 29 a) is set, the number of movements of the null optical system 12 from the start to the end of the shape measurement procedure can be suppressed to one, and the measurement time can be reduced.
  • part or all of the operation of the CPU 29a may be manually performed.
  • the light for switching the optical path is Shirt elements 26a and 26b and half mirror 25a are used as elementary elements. Shirt elements 26a and 26b are omitted and all parts that can be removed from the position of half mirror 25a are omitted. A reflection mirror may be provided.
  • a third embodiment of the present invention will be described with reference to FIG. Here, only differences from the first embodiment will be described.
  • FIG. 5 is a diagram illustrating a shape measurement procedure according to the present embodiment.
  • a calibration null optical system 31 as shown in (1) is prepared.
  • the reflective zone plate 30 is designed in accordance with the design shape of the aspheric surface 11a to be inspected, and its diffraction surface 30a is arranged in the arrangement shown in FIG. At a distance L a), the reflection effect is equivalent to that of the aspheric surface 11a.
  • the calibration null optical system 31 is designed according to the design shape of the aspheric surface 11a to be inspected or the design shape of the reflection zone plate 30.
  • the interference fringes due to the light reflected from the diffraction surface 30a and the light reflected from the entire surface 31aa of the Fize Null optical system 31 for calibration is designed so that is a single stripe color.
  • the angle of incidence S of the light beam on the diffraction surface 30a is designed to be the same sign as the angle of incidence in the arrangement of FIG. 5B.
  • the calibration null optical system 31 may be configured by any of a diffractive optical element, a refractive lens, and a combination of a diffractive optical element and a refractive lens.
  • a Fizeau lens provided with an aspherical Fizeau may be used. JP03 / 02842
  • the calibration null optical system 31 includes a planar Fizeau member 31 a and a wavefront conversion lens 31 b in order from the light source side.
  • the Fizeau surface 31a is a surface of the Fizeau member 31a on the wavefront conversion lens 31b side.
  • the shape information (interference fringe phase distribution data) of the test aspheric surface 11a based on the null optical system 12 obtained by ordinary interference measurement (FIG. 5 (a)) is expressed as W1 Too ⁇ 0
  • the reflected wavefront WU of the reflective zone plate 30 is measured using the null optical system 12, and the wavefront in the null optical system 12 is measured.
  • the shape information (phase distribution data of interference fringes) W 2 ′ of the reflected wavefront WU based on the conversion unit 1 2 ′ is obtained.
  • the interferometer 14 prepares the same interferometer 14 as in the normal interferometer or another interferometer configured in the Fizeau type, insert the null optical system 12 into the measurement light beam of the interferometer, and connect the null optical system 12
  • a reflective zone plate 30 is arranged at the position of the reference remote distance L a with the diffraction surface 30 a facing the null optical system 12, and in this state, the interferometer is driven to form interference fringes.
  • phase distribution data W 2 ′ of the interference fringes is obtained. Note that what is detected here is an interference fringe formed by the reflected wavefront WU of the reflective zone plate 30 and the reflected wavefront of the Fizeau surface 12 aa.
  • the reflected wavefront WV of the reflective zone plate 30 is measured by using the calibration null optical system 31 to perform calibration. Obtain the shape information (phase distribution data of interference fringes) W 3 ′ of the reflected wavefront WV based on the null optical system 31 1.
  • the Fizeau surface 12aa in the null optical system 12 is moved from the final surface 12 bb side using the null optical system 31 for calibration. Interference measurement is performed, and error information (phase distribution data of interference fringes) W4 of the wavefront transforming unit 12 'in the null optical system 12 is acquired with reference to the null optical system 31 for calibration.
  • the same interferometer 14 as in the normal interferometer or another interferometer configured in a Fizeau type is prepared, and the calibration null optical system 31 is inserted into the measurement light beam of the interferometer, and the null null for calibration is provided.
  • the null optical system 12 is arranged at a position at a remote distance Lc with respect to the optical system 31 with the final surface 31 bb facing the final surface 12 bb, and the interferometer is driven in that state. Then, the interference fringes are detected, and the interference fringes are analyzed to obtain phase distribution data W4 of the interference fringes. Note that what is detected here is an interference fringe formed by the reflected wavefront of the Fizeau surface 3 la a and the reflected wavefront of the Fizeau surface 12 aa.
  • the acquired phase distribution data W1 includes the shape error ES of the test aspheric surface 11a, the wavefront error and the shape error (EF + EW) of the wavefront conversion unit 1 2 'in the null optical system 12. ) Are superimposed (EF is the shape error of the Fizeau surface 12 aa, and EW is the transmitted wavefront error of the wavefront conversion lens 12 b).
  • the wavefront error (equivalent reflection surface error) EU of the reflection wavefront WU of the reflection type zone plate 30 and the wavefront error and the shape error (EF + EW) of the wavefront conversion unit 12 ′ are superimposed on the phase distribution data W2 ′.
  • the phase distribution data W 3 ′ includes the wavefront error (equivalent reflection surface error) of the reflection wavefront WV of the reflection zone plate 30 and the wavefront conversion unit 3 1 ′ (the Fizeau surface 3 1) in the calibration null optical system 31.
  • the wavefront error and the shape error (EF '+ EW') of the optical system from aa to the final surface 31 bb) are superimposed (EF, where the shape error of the Fizeau surface 31aa and EW 'is the wavefront transformation This is the transmitted wavefront error of the lens 31b).
  • the phase distribution data W4 includes the wavefront error and shape error (EF + EW) of the wavefront conversion unit 12 'in the null optical system 12, and the wavefront error and shape of the wavefront conversion unit 31' in the calibration null optical system 31. Error (EF '+ EW) is superimposed.
  • Equivalent reflective surface error EU, EV error component due to surface shape error of pattern surface on reflective zone plate 30, error component due to in-plane variation error of depth (height) of diffraction pattern, coordinates of diffraction pattern It consists of error components due to errors.
  • the equivalent reflection surface errors EU and EV are expressed by the following equation (6).
  • each of the phase distribution data Wl, W2 ', W3', and W4 obtained in the shape measurement procedure is an actually measured value.
  • the value of the error component EP ′ due to the coordinate error can be measured directly from the reflective zone plate 30 with sufficient accuracy (by a coordinate measuring machine or the like).
  • the relationship between the coordinate error ⁇ X and the phase distribution deviation E is the pattern position of the pitch P. 0302842
  • the Fizeau surface 12 aa of the null optical system 12 is changed to the final surface 12 bb using the null optical system 31 for calibration.
  • the measurement is performed from the side, but the relationship between the two is reversed, and the Fizeau surface 31 aa of the calibration null optical system 31 using the null optical system 12 is measured from the final surface 31 bb side. It is possible to acquire the shape information of the single object of the aspheric surface to be inspected 1a with high accuracy.
  • the calibration in the second calibration interferometer (FIG. 5 (c)) and the third calibration interferometer (FIG. 5 (d)), the calibration can be performed by using a common reference light generation element. Even if a null optical system 31 having no Fizeau surface 31aa is used, almost the same effect can be obtained.
  • the Fizeau surface 31aa is not provided as the calibration null optical system 31. If used, a Twyman-Green interferometer may be used.
  • FIG. 6 shows an example in which the test aspheric surface 11a is a convex surface, the present embodiment can be similarly applied to a case where the test aspheric surface 11a is a concave surface.
  • an interference measurement system for efficiently performing the present embodiment is configured in the same manner as the interference measurement system for efficiently performing the first embodiment (see the second embodiment, FIG. 4). You may.
  • the irradiation direction of the measurement light beam is reversible
  • the test object 11 is supported so as to be able to move away from the measurement light beam
  • the reflection zone plate 30 is supported.
  • an optical arrangement mechanism for supporting the measurement light beam so that it can be inserted and removed and turned over.
  • a fourth embodiment of the present invention will be described with reference to FIG. Here, only differences from the third embodiment will be described.
  • FIG. 6 is a diagram illustrating an interference measurement procedure according to the present embodiment.
  • an optical system for causing the aspheric surface 11 a to be measured to act as one Fiso surface (referred to as “work Fizeau optical system” in this specification) 6 7 are prepared. Then, only the second calibration interference measurement described below is performed instead of the second calibration interference measurement and the third calibration interference measurement described in the third embodiment.
  • the work Fizeau optical system 67 has the shape of the test object 11 (the shape of the test aspheric surface 11 a and the shape of the back surface lib, the distance between the test aspheric surface 11 a and the back surface lib, and the shape of the test object 11). It converts the incident parallel luminous flux into a luminous flux with a predetermined wavefront according to the shape of the specimen 11.
  • the work Fizeau optical system 67 is arranged between the test object 11 and the interferometer 14 in the second calibration interference measurement.
  • the test object 11 is placed with its back surface 11 b facing the work Fizeau optical system 67.
  • the luminous flux of the predetermined wavefront emitted from the work Fizeau optical system 67 enters from the back surface 11b side of the test object 11 and then enters the test aspheric surface 11a in substantially the same phase in the perpendicular direction. I do.
  • the work Fizeau optical system 67 that converts a parallel light beam into a light beam having such a predetermined wavefront may be configured by any optical element, for example, a plurality of refractive lenses.
  • the shape information (phase distribution data of interference fringes) of the test aspheric surface 11a based on the null optical system 12 and obtained by ordinary interference measurement is referred to as W1. ⁇ .
  • the shape information of the wavefront WU reflected by the reflective zone plate 30 based on the null optical system 12 (the phase distribution of the interference fringes) obtained by the first calibration interferometry shown in FIG. Data) is W2 '.
  • the shape information of the reflected wavefront WV of the reflective zone plate 30 is measured with reference to the aspheric surface 11a to be measured. That is, the same interferometer 14 as that used for normal interferometry or another interferometer configured in a Fizeau type is prepared, and the work Fizeau optical system 67, the test object 11, and the reflection zone are added to the measurement light beam of the interferometer. With the plate 30 inserted, the interferometer is driven with the aspheric surface under test 11a as the Fizeau surface and the diffraction surface 30a as the test surface to detect interference fringes and analyze the interference fringes. To obtain the phase distribution data W 3 ′′ of the interference fringes.
  • the distance from the diffraction surface 30a in the arrangement state shown in FIG. 6 to the aspheric surface 11a to be measured is calculated in the arrangement state shown in FIG. From the distance between the null optical system 12 and the aspheric surface 11a to be examined (see Fig. 5 (a)), the distance from the diffraction surface 30a to the null optical system 12 in the arrangement shown in Fig. 5 (b) is determined. It is equal to the distance La.
  • the shape error ES of the test aspheric surface 11a and the wavefront error (EF + EW) of the wavefront transforming unit 12 'in the null optical system 12 are superimposed (EF is The shape error of the Fiso surface 12 aa, and EW is the transmitted wavefront error of the wavefront conversion lens 12 b).
  • phase distribution data W2 ' is superimposed with the equivalent reflection surface error EU of the reflection type zone plate 30 and the wavefront error (EF + EW) of the wavefront conversion unit 12'.
  • the work Fizeau optical system 67 uses the reference light (here, the light reflected on the aspheric surface 11a to be measured). This is because they are arranged on the common optical path of the reference light and the measurement light (light reflected on the diffraction surface 30a). (In general, in an interferometer, the wavefront shape in the common optical path of the reference light and the measurement light has no effect on the measurement result. Do not give.)
  • the shape error ES of the test aspheric surface 11a is expressed as the equation (12).
  • Wl, W2 ', W3 are actual measurement values, and the error component EP' is sufficient to measure the pattern coordinates of the reflective zone plate 30 with a coordinate measuring machine or the like. Can be obtained with precision.
  • the shape error E S of the aspheric surface 11 a to be measured is obtained from the equation (12).
  • the shape information of the single aspheric surface 11a to be obtained can be obtained only by a total of three measurements. It is possible to do.
  • An interference measurement system for efficiently implementing the present embodiment is configured in the same manner as the interference measurement system for efficiently implementing the first embodiment (see the second embodiment, FIG. 4). You may.
  • FIG. 7 is a schematic configuration diagram of the projection exposure apparatus of the present embodiment.
  • the whole or a part of the optical surface 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. Then, at least any surface of the projection optical system PL and any part of the Z or the projection exposure apparatus are adjusted according to the measurement result.
  • the projection lens 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 at least a wafer stage 108, a light source unit 101 for supplying light, and a projection optical system PL.
  • the wafer stage 108 can place the wafer w coated with the photosensitive agent on the surface 108 a.
  • the stage control system 107 controls the position of the wafer stage 108.
  • the projection optical system PL is a high-precision projection lens manufactured using the interferometer of each of the above embodiments as described above.
  • a wafer w is disposed on the object plane P1 and the image plane P2 of the projection optical system PL with a reticle, respectively.
  • the projection optical system PL has an alignment optical system applied to a scan type projection exposure apparatus.
  • illumination optical system 102 includes an alignment optical system 103 for adjusting a relative position between reticle r and wafer w.
  • the reticle / lens is used to project an image of the pattern of the reticle layer r onto the wafer w, and the reticle stage 10 is capable of moving parallel to the surface 108 a of the wafer stage 108. 5 placed on.
  • the reticle exchange system 104 exchanges and transports the reticle r set on the reticle stage 105.
  • reticle exchange system 104 includes a stage driver (not shown) for moving reticle stage 105 parallel to surface 108 a of wafer stage 108.
  • the main control unit 109 controls a series of processes from alignment to exposure.
  • the magnitude of the order of the diffracted light used in the calibration interference measurement of each shape measurement may be two or more. However, in general, the intensity of the diffracted light increases as the order decreases, so that setting to “1” enables more accurate measurement. Further, any of the above shape measurements may be applied to make the shape of a reference prototype (a prototype used as a reference for comparison measurement) known. If the shape of the reference prototype is known by any of the above-mentioned shape measurements, the shape of each test surface can be measured by simply measuring each test surface once by ordinary interference measurement. It can be easily obtained from the measurement results obtained when the reference prototype is measured in the same way and the known shape of the reference prototype.
  • each shape measurement only the shape information of the aspherical surface to be inspected 1 a was acquired, and the same measurement as 1S was used to obtain the error (transmitted wavefront error) of the wavefront conversion unit 1 2 ′ in the null optical system 12. Is also possible. This is applicable to the calibration of interferometers. If either the shape of the surface to be measured or the error of the wavefront converter 12 ′ (transmitted wavefront error) is known, the pattern error of the transmission zone plate or the reflection zone plate is used. Can also be extracted.
  • a transmission zone plate (or a reflection zone plate) is produced by the patterning apparatus thus verified, or a transmission zone plate (or a reflection zone plate) is prepared by the pattern coordinate measuring apparatus thus verified. If any of the above shape measurements is performed after measuring the coordinate error of the reflective zone plate), the result can be obtained with higher accuracy.
  • the shape information of the simple substance of a to-be-tested surface can be acquired from the measurement result obtained by the interference measurement using a null optical system, without being affected by the error resulting from a null optical system.
  • a shape measurement method is realized.
  • an interference measuring device capable of efficiently performing the shape measurement is realized.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Instruments For Measurement Of Length By Optical Means (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

Procédé servant à acquérir une information de forme sur un élément unique d'une surface à détecter à partir de résultats de mesure obtenus par mesure d'interférence au moyen d'un système optique zéro sans subir les inconvénients de ce système. Procédé de mesure d'interférence consistant à mesurer une surface à détecter au moyen d'un système optique zéro composé d'une surface de Fizeau située sur une surface non finale. La surface à détecter est soumise à des mesures d'interférence au moyen une plaque de zone de transmission conçue de telle sorte que le front d'ondes de la lumière de diffraction d'un ordre m-th d'émission apparaissant quand un flux lumineux de mesure est incident, est équivalent à la forme de la surface à détecter. De plus, la surface de Fizeau de ce système optique zéro est soumise à une mesure d'interférence depuis le côté de ladite surface finale au moyen de la plaque de zone de transmission. Un traitement arithmétique est ensuite effectué en fonction des éléments d'information respectifs acquis par les mesures d'interférence respectives afin de déterminer l'information de forme sur l'élément unique de la surface à détecter.
PCT/JP2003/002842 2002-03-12 2003-03-11 Procede de mesure de forme, dispositif de mesure d'interference, procede d'elaboration d'un systeme optique de projection et dispositif d'alignement WO2003076872A1 (fr)

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DE102006035022A1 (de) * 2006-07-28 2008-01-31 Carl Zeiss Smt Ag Verfahren zum Herstellen einer optischen Komponente, Interferometeranordnung und Beugungsgitter
KR101124018B1 (ko) 2009-12-15 2012-03-23 인하대학교 산학협력단 비구면 렌즈 측정장치
DE102011004376B3 (de) * 2011-02-18 2012-06-21 Carl Zeiss Smt Gmbh Verfahren und Vorrichtung zum Bestimmen einer Form einer optischen Testfläche
DE102012217800A1 (de) * 2012-09-28 2014-04-03 Carl Zeiss Smt Gmbh Diffraktives optisches Element sowie Messverfahren

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