JP2014116438A - Method and device for computing light quantity distribution, recording medium with program for computing light quantity distribution recorded thereon, and exposure method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and highly accurately compute light quantity distribution, on a pupil surface of a projection optical system, of diffraction light generated from a pattern.SOLUTION: A method for computing light quantity distribution, on a projection pupil surface, of light from patterns of a reticle includes: steps 112-116 for inputting information about a table recording therein computation results of intensity information of zero-order diffraction light and first-order diffraction light which are generated when a plurality of patterns having different cycles among the patterns are irradiated with light at first and second incident angles, a Fourier transformation pattern obtained from the patterns and an illumination pupil; and steps 118-122 for obtaining partial light quantity distribution on a projection pupil surface on the basis of a Fourier transformation pattern obtained by correcting a plurality of partial Fourier transformation patterns separated from the Fourier transformation pattern while using the table for each of a plurality of partial illumination pupils of the illumination pupil.

Description

  The present invention relates to a calculation technique for calculating a light quantity distribution of light generated from a pattern, a recording medium on which a program for calculating the light quantity distribution is recorded, and a calculation technique for calculating optical characteristics of a projection optical system that forms an image of the pattern The present invention relates to an exposure technique using these calculation techniques, and a device manufacturing technique using the exposure techniques.

  For example, in an exposure apparatus (projection exposure apparatus) such as a stepper or a scanning stepper used in a lithography process for manufacturing an electronic device (microdevice) such as a semiconductor device or a liquid crystal display element, a pattern of a reticle (mask) is increased. In order to accurately expose a substrate such as a wafer, the optical characteristics (for example, aberration) of the projection optical system must be maintained within a target range. In this regard, when the exposure is continued, the optical characteristics of the projection optical system gradually change depending on the accumulated irradiation energy.

  Therefore, conventionally, an imaging characteristic correction system that predicts the amount of change in the optical characteristics of the projection optical system during exposure, for example, according to the integrated irradiation energy, and corrects the position and angle of a predetermined optical member in the projection optical system, for example. Is used to correct the predicted variation in the optical characteristics (see, for example, Patent Document 1). In this case, as an example, when using the reticle for the first time, before actually exposing the substrate, measure how the optical characteristics of the projection optical system fluctuate according to the integrated irradiation energy, During the exposure, the variation amount of the optical characteristic is predicted based on the measurement result and the integrated irradiation energy.

US Patent Application Publication No. 2006/244940

  As is conventional, each time the first use example reticle and how the optical characteristics in advance before the exposure to perform the method to be measured or to change, possibly productivity of the exposure step (throughput) is reduced is there. Therefore, for example, it is preferable to obtain by calculation how the optical characteristics of the projection optical system fluctuate according to the integrated irradiation energy. For this purpose, the light amount distribution of the diffracted light (including zero-order light) generated from the reticle pattern on the pupil plane (or entrance pupil or exit pupil) of the projection optical system is calculated with high accuracy. There is a need.

  Also, since the pattern of recent reticles is becoming increasingly finer, for example, when the pattern is formed on a thin film, in order to accurately calculate the light intensity distribution of the diffracted light, the pattern is used as the structure of the thin film. Need to be considered as a three-dimensional pattern. However, if the actual reticle pattern is regarded as a three-dimensional pattern and the light amount distribution of the diffracted light generated from the pattern is calculated by, for example, strict electromagnetic field analysis (for example, Maxwell equation), the amount of calculation and the calculation time are reduced. It becomes enormous and the practicality decreases. For this reason, it is preferable that the light quantity distribution can be calculated with relatively small accuracy with a smaller calculation amount.

  In view of such circumstances, an aspect of the present invention is to enable an efficient and highly accurate calculation of a light amount distribution on a pupil plane of a projection optical system of diffracted light generated from an exposure pattern, for example. And

  According to the first aspect of the present invention, there is provided a light amount distribution calculation method for calculating a light amount distribution on a pupil plane of a projection optical system that receives light from a predetermined pattern. In this calculation method, when a plurality of periodic patterns having different periods among the predetermined patterns are illuminated with lights having different first and second incident angles, the first and second orders having different orders are generated. Input the information of the table in which the calculation result of the intensity information of the diffracted light is recorded, and input the Fourier transform pattern information of the predetermined pattern obtained by calculating the predetermined pattern as a two-dimensional pattern And inputting information on the illumination pupil of the illumination optical system that illuminates the predetermined pattern, and using the information of the Fourier transform pattern, a plurality of patterns generated by the partial patterns having different periods from the Fourier transform pattern Using the information of the illumination pupil to separate the partial Fourier transform pattern, the illumination pupil is divided into a plurality of partial illumination pupils, Obtaining a partial light quantity distribution on the pupil plane of the projection optical system based on a corrected partial Fourier transform pattern obtained by correcting the plurality of partial Fourier transform patterns using the table for each partial illumination pupil of Adding the partial light quantity distribution obtained for each partial illumination pupil to obtain the light quantity distribution.

Further, according to the second aspect, in the calculation method of the optical characteristics of the projection optical system that forms an image of a predetermined pattern illuminated with light from the illumination optical system, the light quantity distribution calculation method of the first aspect is used. Determining the light quantity distribution of the light from the predetermined pattern on the pupil plane of the projection optical system, determining the optical characteristics of the projection optical system using information on the light quantity distribution on the pupil plane of the projection optical system, A calculation method is provided.
According to the third aspect, in the exposure method of illuminating a predetermined pattern with the light from the illumination optical system and exposing the substrate with the light through the predetermined pattern and the projection optical system, the light amount of the aspect of the present invention Determining the light quantity distribution of the light from the predetermined pattern on the pupil plane of the projection optical system using the distribution calculation method, and the optical of the projection optical system based on the information on the light quantity distribution on the pupil plane of the projection optical system An exposure method is provided that includes determining a variation amount of the characteristic and correcting the determined variation amount of the optical characteristic.

  According to the fourth aspect, there is provided a light amount distribution calculating device for calculating a light amount distribution on a pupil plane of a projection optical system that receives light from a predetermined pattern. The calculation device is configured to illuminate a plurality of periodic patterns having different periods among the predetermined patterns with lights having different first and second incident angles, and generate first and second orders having different orders. Information on the table in which the calculation result of the intensity information of the diffracted light is recorded, information on the Fourier transform pattern of the predetermined pattern obtained by calculating the predetermined pattern as a two-dimensional pattern, and illuminating the predetermined pattern A plurality of partial Fourier transform patterns generated by partial patterns having different periods from the Fourier transform pattern using the storage device for storing the information of the illumination pupil of the illumination optical system and the information of the Fourier transform pattern. Using the information of the illumination pupil, the illumination pupil is divided into a plurality of partial illumination pupils, and the table is divided for each partial illumination pupil. The partial light quantity distribution on the pupil plane of the projection optical system is obtained based on the corrected partial Fourier transform pattern obtained by correcting the plurality of partial Fourier transform patterns using And an arithmetic unit that obtains the light quantity distribution by adding the partial light quantity distributions.

According to the fifth aspect, the optical characteristic calculation device of the projection optical system that forms an image of a predetermined pattern illuminated with light from the illumination optical system includes the light amount distribution calculation device of the fourth aspect. The calculation apparatus includes an optical characteristic calculation apparatus that obtains optical characteristics of the projection optical system using information on a light amount distribution of light from the predetermined pattern on the pupil plane of the projection optical system obtained by the arithmetic unit. An apparatus is provided.
According to the sixth aspect, in the exposure apparatus that illuminates the predetermined pattern with the light from the illumination optical system and exposes the substrate with the light through the predetermined pattern and the projection optical system, the light amount of the aspect of the present invention A distribution calculation device, and a variation amount of the optical characteristics of the projection optical system based on information on the light amount distribution of the light from the predetermined pattern on the pupil plane of the projection optical system obtained by the calculation device, and the optical characteristics An exposure apparatus is provided that includes a control device that corrects the amount of fluctuation in the above.

Moreover, according to the seventh aspect, forming the pattern of the photosensitive layer on the substrate using the exposure method or the exposure apparatus of the aspect of the present invention, processing the substrate on which the pattern is formed, A device manufacturing method is provided.
According to the eighth aspect, the computer executes the processing of the light amount distribution calculation method according to the aspect of the present invention for calculating the light amount distribution on the pupil plane of the projection optical system that receives light from the predetermined pattern. A computer-readable recording medium on which a program for recording is recorded is provided.

  According to the aspect of the present invention, even when the predetermined pattern is a three-dimensional pattern, for example, when the predetermined pattern is calculated more efficiently than when a strict electromagnetic field analysis is performed and the predetermined pattern is regarded as a two-dimensional pattern The light amount distribution on the pupil plane of the projection optical system of the diffracted light generated from the predetermined pattern can be calculated with higher accuracy.

It is a figure which shows schematic structure of the exposure apparatus which concerns on an example of embodiment. 2 is a block diagram showing a control system and the like of the exposure apparatus of FIG. (A) is an enlarged plan view showing an example of a periodic pattern, (B) is a cross-sectional view showing a case where illumination light is perpendicularly incident on the pattern of FIG. 3 (A), and (C) is a pattern of FIG. 3 (A). It is sectional drawing which shows the case where illumination light injects with the maximum inclination angle. It is a figure which shows an example of the exact calculation result of the amplitude of two diffracted lights according to the pitch (period) in case illumination light makes normal incidence and oblique incidence in a line and space pattern (L & S pattern). (A) is an enlarged plan view showing a part of an example of a reticle pattern for actual exposure, (B) is a sectional view of FIG. 5 (A), and (C) is a two-dimensional pattern of FIG. 5 (A). It is a figure which shows an example of the Fourier-transform pattern when it sees as a pattern. (A) is a diagram showing a Fourier transform pattern of the first and higher order diffracted light of the first L & S pattern, (B) is a diagram showing a Fourier transform pattern of the first and higher order diffracted light of the second L & S pattern, (C ) Is a diagram showing Fourier transform patterns of the 0th-order and 1st-order diffracted light of the first L & S pattern, and (D) is a diagram showing Fourier transform patterns of the 0th-order and 1st-order diffracted light of the second L & S pattern. is there. (A) is a diagram showing an example of an illumination pupil, (B) is a diagram showing an example of a method for dividing an illumination pupil, (C) is a diagram showing a first partial illumination pupil, and (D) is a first partial illumination. The figure which shows an example of the result of convolving a pupil and a Fourier-transform pattern, (E) is a figure which shows the 2nd partial illumination pupil, (F) is the 2nd partial-illumination pupil, and the Fourier-transform pattern was convolved It is a figure which shows an example of a result. (A) is a figure which shows an example of the result of integrating | accumulating several light quantity distribution, (B) is a figure which shows an example of the light quantity distribution in the pupil plane of a projection optical system. (A) is a flowchart showing an example of a preparation process of light quantity distribution calculation, and (B) is a flowchart showing an example of light quantity distribution calculation and exposure process. (A) is a view showing an example of an illumination pupil, (B) is a view showing a light amount distribution calculated as a two-dimensional pattern, (C) is a view showing a light amount distribution calculated by the method of the present embodiment, and (D) is a view showing the light amount distribution. It is a figure which shows the light quantity distribution measured. (A) is an enlarged plan view showing a part of another reticle pattern, and (B) is an example of a Fourier transform pattern when the pattern of FIG. 11 (A) is viewed as a two-dimensional pattern. It is a figure which shows an example of the light quantity ratio of the 1st-order light and 0th-order light obtained by calculating with the calculation method of this embodiment and another calculation method regarding various patterns. It is a figure which shows an example of the light quantity distribution of the diffracted light which generate | occur | produces from the L & S pattern obtained by calculating with the calculation method of this embodiment and another calculation method. It is a flowchart which shows an example of the manufacturing process of an electronic device.

An example of an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 schematically shows the overall configuration of an exposure apparatus EX according to the present embodiment. The exposure apparatus EX is, for example, a scanning exposure type projection exposure apparatus composed of a scanning stepper (scanner). The exposure apparatus EX includes a projection optical system PL. Hereinafter, a reticle R and a semiconductor wafer (hereinafter referred to as a wafer) W are taken in a plane (a plane parallel to a horizontal plane in this embodiment) orthogonal to the Z axis parallel to the optical axis AX of the projection optical system PL. In the following description, the Y axis is taken in the direction in which the and are relatively scanned, and the X axis is taken in the direction perpendicular to the Z axis and the Y axis. In addition, the rotation directions around the axes parallel to the X axis, the Y axis, and the Z axis are also referred to as θx, θy, and θz directions.

  The exposure apparatus EX includes an exposure light source 30 that generates exposure illumination light (exposure light) IL, an illumination optical system ILS that illuminates a reticle R (mask) using the illumination light IL from the light source 30, and a reticle R. Is provided with a reticle stage RST that moves while holding. Further, the exposure apparatus EX includes a projection optical system PL that exposes the wafer W (substrate) with illumination light IL emitted from the reticle R, a wafer stage WST that holds and moves the wafer W, and illumination light emitted from the reticle R. From a calculation device 10 (see FIG. 2) for calculating the light amount distribution on the pupil plane PLP (or entrance pupil or exit pupil) of the projection optical system PL of IL (diffracted light), and a computer that comprehensively controls the operation of the entire device. And the like (see FIG. 2). The exposure main body (illumination optical system ILS, reticle stage RST, projection optical system PL, and wafer stage WST) of the exposure apparatus EX is installed in an environmental chamber (not shown) to which a temperature-controlled clean gas is supplied. Has been.

  As the illumination light EL, for example, ArF excimer laser light (wavelength 193 nm) is used. As illumination light, KrF excimer laser light (wavelength 248 nm), harmonics of a YAG laser or a solid-state laser (semiconductor laser, etc.), or a bright line (i-line etc.) of a mercury lamp can be used. The illumination optical system ILS is linearly polarized or non-polarized in a predetermined direction supplied from the light source 30 as indicated by a dotted line and as disclosed in, for example, US Patent Application Publication No. 2003/0025890. A mirror MR1 that reflects illumination light EL for exposure such as polarized light, a spatial light modulator 32 that reflects the reflected light by an array of many tilt angle variable mirror elements, and collects light from the array of mirror elements It has a condensing optical system 33 and a mirror MR2 that reflect, and a fly-eye lens 34 (optical integrator) that forms a surface light source (illumination pupil) on the exit surface from the reflected light. In the present embodiment, the exit surface of the fly-eye lens 34 is the illumination pupil plane IPP.

  By controlling the inclination angle of each mirror element of the spatial light modulator 32, the light amount distribution (light intensity distribution) of the illumination pupil plane IPP is changed to a light amount (light intensity) in a circular region, a multi-pole region, or an annular region. Can be set to a distribution corresponding to various illumination conditions. A region where the amount of light increases on the illumination pupil plane IPP is referred to as an illumination pupil ILP. If necessary, a variable aperture stop 35 is installed on the illumination pupil plane IPP or in the vicinity thereof. The illumination optical system ILS further includes a condenser optical system 36 that illuminates a slit-like illumination area IAR that is elongated in the X direction of the pattern surface (lower surface) Ra of the reticle R with illumination light EL from the surface light source, and an illumination area It has a variable field stop (not shown) that defines the shape of the IAR. In place of the spatial light modulator 32, a plurality of diffractive optical elements arranged in the illumination optical path in an interchangeable manner can also be used.

  Further, the illumination optical system ILS is provided with a photoelectric sensor (integrator sensor) (not shown) that measures the amount of light branched from the illumination light IL, and the measurement value of the integrator sensor is supplied to the main controller 14. Yes. The main controller 14 can monitor the integrated irradiation energy of the projection optical system PL from the measured value. In addition, it is also possible to use the exposure duration as alternative information for the integrated irradiation energy.

  The reticle R is held on the upper surface of the reticle stage RST by vacuum suction or the like, and a device pattern DP1 (see FIG. 5A) such as a circuit pattern and an alignment mark (not shown) are formed on the pattern surface Ra of the reticle R. Has been. The reticle stage RST can be driven minutely in the XY plane by the reticle stage drive system 41 shown in FIG. 2 including a linear motor, for example, and can be driven at a scanning speed specified in the scanning direction (Y direction).

  Position information within the moving surface of the reticle stage RST (including the position in the X direction, the Y direction, and the rotation angle in the θz direction) is transferred to the moving mirror 22 (or mirror-finished) by the reticle interferometer 24 including a laser interferometer. For example, it is always detected with a resolution of about 0.5 to 0.1 nm via the stage end face. The measurement value of reticle interferometer 24 is sent to main controller 14 in FIG. Main controller 14 controls the position and speed of reticle stage RST by controlling reticle stage drive system 41 based on the measured values.

  In FIG. 1, the projection optical system PL is, for example, both-side telecentric and has a predetermined projection magnification β (for example, a reduction magnification of 1/4 times, 1/5 times, etc.). An aperture stop AS is installed in or near the pupil plane (hereinafter referred to as projection pupil plane) PLP of the projection optical system PL. The projection pupil plane PLP (and the entrance pupil and the exit pupil) is optically conjugate with the illumination pupil plane IPP, and the projection pupil plane PLP is optical with respect to the pattern surface Ra of the reticle R (the object plane of the projection optical system PL). It is also a typical Fourier transform surface. The projection optical system PL may be a type that forms an intermediate image. Further, the projection optical system PL may be a refractive system, but may also be a catadioptric system. When the illumination area IAR of the pattern surface Ra of the reticle R is illuminated by the illumination light IL from the illumination optical system ILS, the device pattern in the illumination area IAR is passed through the projection optical system PL by the illumination light IL that has passed through the reticle R. Is formed in an exposure area IA (an area conjugate with the illumination area IAR) of one shot area of the wafer W. As an example, the wafer W includes a wafer formed by applying a photoresist (photosensitive material) with a thickness of about several tens to 200 nm to a disk-shaped base made of a semiconductor such as silicon and having a diameter of about 200 to 450 mm.

  Further, in the exposure apparatus EX, in order to perform exposure using the liquid immersion method, local liquid immersion is performed so as to surround the lower end portion of the optical element on the most image plane side (wafer W side) constituting the projection optical system PL. A nozzle unit 18 that constitutes a part of the apparatus and supplies and recovers the exposure liquid Lq (for example, pure water) in the liquid immersion area including the exposure area IA is provided. The nozzle unit 18 is connected to a liquid supply device 43 and a liquid recovery device 44 (see FIG. 2) via a pipe (not shown) for supplying the liquid Lq. If the immersion type exposure apparatus is not used, the above-mentioned local immersion apparatus need not be provided.

  In addition, a pipe (not shown) installed so as to be in contact with the holding mechanism of the plurality of optical elements in the projection optical system PL is provided with a liquid Co whose temperature is controlled from the temperature control unit 28 via the supply pipe 29A. (For example, pure water, fluorine-based liquid, refrigerant, or the like) is supplied, and the liquid Co that has flowed through the piping in the projection optical system PL is recovered by the temperature control unit 28 via the recovery piping 29B. By circulating the liquid Co whose temperature is controlled by the temperature controller 28 in the projection optical system PL, the temperature rise of the plurality of optical elements in the projection optical system PL due to the integrated irradiation energy of the illumination light IL is suppressed. .

Further, the projection optical system PL includes an imaging characteristic correction system 16 that corrects optical characteristics (including imaging characteristics) such as distortion and spherical aberration (wavefront aberration) by controlling the postures of a plurality of predetermined lenses. Is provided. Such an imaging characteristic correction system is disclosed in, for example, US Patent Application Publication No. 2006/244940 (Patent Document 1).
Further, the exposure apparatus EX performs an alignment of the wafer W with an aerial image measurement system (not shown) that measures the position of the image of the alignment mark of the reticle R by the projection optical system PL in order to align the reticle R. For example, an image processing type (FIA type) alignment system AL, an irradiation system 45a and a light receiving system 45b, and an oblique incidence type multi-point autofocus sensor for measuring Z positions at a plurality of locations on the surface of the wafer W ( (Hereinafter referred to as a multi-point AF system) 45 (see FIG. 2).

  Wafer stage WST is supported in a non-contact manner on an upper surface parallel to the XY plane of base board WB via a plurality of air pads (not shown). Wafer stage WST can be driven in the X and Y directions by a stage drive system 42 (see FIG. 2) including, for example, a planar motor or two sets of orthogonal linear motors. Wafer stage WST includes a stage main body that is driven in the X direction and the Y direction, a wafer holder WH that is provided on the stage main body and holds wafer W by vacuum suction, the Z position of wafer W, the θx direction, and the θy direction. And a Z stage mechanism (not shown) for controlling the tilt angle.

  In addition, a wafer interferometer 26 composed of a laser interferometer is arranged for measuring position information of wafer stage WST. Instead of the wafer interferometer 26, an encoder type position measurement system combining a diffraction grating and a detector may be used. Position information within the moving surface of wafer stage WST (including the position in the X direction, the Y direction, and the rotation angle in the θz direction) is always detected by the wafer interferometer 26 with a resolution of about 0.5 to 0.1 nm, for example. The measured value is sent to the main controller 14. Main controller 14 controls the position and speed of wafer stage WST by controlling stage drive system 42 based on the measurement value.

  In addition, measurement unit 20 capable of measuring the light amount distribution (light intensity distribution) of projection pupil plane PLP is incorporated in wafer stage WST. The measurement unit 20 has a surface having the same height as the surface of the wafer W, a flat glass substrate 21A having a pinhole formed on the surface, and light receiving optics that collects illumination light that has passed through the pinhole. It has a system 21B, a CCD or CMOS type two-dimensional imaging device 21D that receives illumination light condensed by the light receiving optical system 21B, and a housing 21D that holds these members. With the pinhole of the glass substrate 21A moved into the exposure area IA, the light receiving surface of the image sensor 21C is optically conjugate with respect to the projection pupil plane PLP (or the exit pupil) by the light receiving optical system 21B. By processing the detection signal of the image sensor 21C by an image processing unit (not shown), the light amount distribution on the projection pupil plane PLP can be measured. The measured light quantity distribution is supplied to the main controller 14.

  The main controller 14 composed of a computer includes a plurality of arithmetic processors, a memory, a storage device, and the like. The main control unit 14 includes an input / output unit 48, a recording / reproducing unit 50 that records and reproduces data on a recording medium 51 such as a DVD (digital versatile disk), a CD-ROM, or a flash memory. Data is exchanged between a storage unit 52 such as a semiconductor non-volatile memory, a calculation unit 54 including a calculation processor and a memory, and a host computer 12 that supplies control information to a plurality of exposure apparatuses and a plurality of lithography apparatuses. An interface unit (not shown) is connected. A calculation device 10 (detailed later) that calculates the light amount distribution of the projection pupil plane PLP by the diffracted light from the reticle R is configured including the storage unit 52 and the calculation unit 54. Note that the arithmetic unit 54 may be one function on software of a computer constituting the main control device 14. The program executed by the main control device 14 and the calculation unit 54 is recorded in, for example, the recording medium 51 and can be read from the recording medium 51 by the recording / reproducing unit 50.

  As a basic operation during exposure of the wafer W, after the alignment of the reticle R and the wafer W is performed, the wafer stage WST is moved in the X direction and the Y direction (step movement), so that the shot of the wafer W to be exposed is shot. The area moves to the front of the exposure area of the projection optical system PL. Then, under the control of the main controller 14, the reticle stage RST and the wafer stage WST are synchronously driven while exposing the shot area of the wafer W with an image of a part of the pattern of the reticle R by the projection optical system PL. By scanning the reticle R and the wafer W with respect to the projection optical system PL in the Y direction, for example, using the projection magnification as the speed ratio, the image of the pattern of the reticle R is scanned and exposed over the entire shot area. By repeating the step movement and the scanning exposure in this way, a pattern image of the reticle R is sequentially exposed to a plurality of shot regions of the wafer W by a step-and-scan method.

  If such exposure is continued, the illumination light IL made up of diffracted light (including zero-order light) generated from the device pattern of the reticle R passes through the projection optical system PL, and is integrated into the projection optical system PL by the accumulated irradiation energy. The temperature of the plurality of optical elements gradually increases, and the optical characteristics (aberration) of the projection optical system PL vary. In the present embodiment, since the temperature-controlled cooling liquid Co is supplied from the temperature control unit 28 into the projection optical system PL, the temperature distribution of these optical elements gradually saturates from the reticle R. The generated diffracted light converges to a certain temperature distribution according to the light amount distribution on the projection pupil plane PLP. Further, each optical element has a very small coefficient of thermal expansion, so that the amount of deformation is small, but the refractive index distribution slightly changes according to the temperature distribution. Therefore, the fluctuation amount of the temperature distribution from the light amount distribution to the convergence on the projection pupil plane PLP and the temperature distribution at the time of convergence are obtained by calculation, and the optical element (or the optical characteristic variation most greatly contributes from the obtained temperature distribution). By calculating the refractive index distribution of the partial optical elements), it is possible to calculate the fluctuation amount of the optical characteristics of the projection optical system PL at each time point during the exposure.

  The light quantity distribution on the projection pupil plane PLP can be measured by driving the wafer stage WST and moving the measurement unit 20 to the exposure area IA. However, in order to suppress a reduction in the throughput of the exposure process, the measurement unit 20 is It is preferable that the measurement of the used light amount distribution can be omitted. Therefore, hereinafter, a method of calculating the light amount distribution on the projection pupil plane PLP of the diffracted light generated from the reticle R using the calculation device 10 and a method of exposing the wafer W while correcting the optical characteristics using the calculation results are described. An example will be described.

  As shown in FIG. 5A, the reticle R device pattern DP1 includes a line and space pattern (hereinafter referred to as an L & S pattern) 62A having a pitch (period) p1 in the X direction and a pitch p1 in the X direction. The L & S patterns 62A and 62B having a smaller pitch p2 are formed on the light-shielding thin film 58 on the lower surface of the flat light-transmitting glass substrate 56. In this case, the line portions 62Aa and 62Ba of the L & S patterns 62A and 62B are rectangular opening patterns elongated in the Y direction in the thin film 58, the space portions 62Ab and 62Bb are portions of the thin film 58, and the duty of the L & S patterns 62A and 62B. The ratio (ratio between the width of the line portion and the width of the space portion) is 1: 1.

Further, as shown in FIG. 5B, as an example, the thin film 58 includes a first thin film 58a made of a metal such as chromium (Cr) having a thickness d1, and a chromium oxide (CrO ₃ ) having a thickness d2. And a second thin film made of an oxide film or the like. As an example, the thickness d1 is about 80 to 90 nm (for example, 85 nm), the thickness d2 is about 10 to 20 nm (for example, 15 nm), and the thickness of the thin film 58 is about 100 nm. Further, since the pitches p1 and p2 of the L & S patterns 62A and 62B are smaller than, for example, about 200 nm, the device pattern DP1 can be regarded as a three-dimensional pattern in which the influence of the thin film 58 cannot be ignored. Therefore, in order to calculate the light quantity distribution on the projection pupil plane PLP of the diffracted light (including the 0th order light) generated from the device pattern DP1, it is necessary to consider the influence of the thin film 58. On the other hand, if strict electromagnetic field analysis is performed according to the illumination conditions with respect to the device pattern DP1, the calculation amount and the calculation time become enormous, and the practicality decreases. Therefore, in the present embodiment, the light amount distribution is calculated with a small amount of calculation while considering the influence of the thin film 58 according to the illumination conditions as follows.

  First, as shown in the flowchart of FIG. 9A, a preparation process for calculating the light amount distribution is executed. The calculation of this preparation process is executed in advance by, for example, the host computer 12 of FIG. 2, and the calculation result is supplied to the main controller 14 of the exposure apparatus EX as necessary. First, in step 102 of FIG. 9A, as shown in FIG. 3A, in the thin film 58 on the pattern surface of the glass substrate 56, the line portion 60a having the line width p / 2 in the X direction and the line width p / Assuming an L & S pattern 60 in which two space portions 60b are formed at a pitch p in the X direction, as shown in FIG. 3B, the configuration of the thin film 58 is the device pattern DP1 of the reticle R in FIG. Similar to the formed thin film 58, it has a two-layer structure of a first thin film 58a having a thickness d1 and a second thin film 58b having a thickness d2. Then, in the host computer 12, the illumination light Lin (with an amplitude of 1) is incident vertically (with an incident angle of 0 degrees) on the L & S pattern 60 in the thin film 58 by strict electromagnetic field analysis using the Maxwell equation, for example. In this case, the amplitude (intensity information) of the 0th-order light L (0) and the ± 1st-order diffracted lights L (+1) and L (−1) generated from the L & S pattern 60 is calculated. Since the square of the absolute value of the amplitude becomes the intensity, the intensity may be calculated. Further, this calculation is performed while changing the pitch p of the L & S pattern 60 from, for example, about 70 nm to about 500 nm in steps of several nm, for example. Within the variable range of the pitch p, the pitches p1 and p2 of the L & S patterns 62A and 62B of the reticle R in FIG. 5A are included. By interpolating this calculation result with respect to the pitch p, for example, as shown in FIG. 4, solid line curves A0 and A1 (first calculation result) are obtained as the amplitudes of the zeroth-order light and the first-order diffracted light in the case of normal incidence. It is done.

  In the next step 104, the illumination light Lin (amplitude is 1) is applied to the L & S pattern 60 in the thin film 58 by strict electromagnetic field analysis using, for example, Maxwell's equation in the host computer 12, as shown in FIG. The amplitudes of the 0th-order light L (0) and the + 1st-order diffracted light L (+1) generated from the L & S pattern 60 when incident at the maximum possible tilt angle θmax by the illumination optical system ILS in the X direction are, for example, 70 nm to 500 nm. Calculation is made within a range of a pitch p of about. As a result, as shown in FIG. 4, dotted curves B0 and B1 (second calculation results) are obtained as the amplitudes of the zeroth-order light and the first-order diffracted light when incident at the maximum inclination angle (oblique incidence). In the next step 106, the host computer 12 creates a table TB1 in which the first and second calculation results are recorded, and stores the table TB1 in an internal storage device.

  As described above, it is possible to calculate the amplitude of diffracted light generated from a simple L & S pattern having a certain thickness with respect to illumination light having two incident angles with a relatively small amount of calculation and calculation time. It is. The table TB1 is a table in which the amplitudes (intensities) of the 0th order light and the 1st order diffracted light generated when the periodic direction is perpendicularly incident on the L & S pattern in the Y direction and incident at the maximum inclination angle in the Y direction are recorded. Can also be used. Furthermore, the table TB1 can be used in common for many types of reticles.

  In the next step 108, the host computer 12 regards the device pattern DP1 of the reticle R in FIG. 5A as a two-dimensional pattern (assuming the thickness of the thin film 58 is 0) and performs, for example, FFT calculation in FIG. As shown in C), the Fourier transform pattern SP1 of the device pattern DP1 is calculated, and the calculation result is stored in the internal storage device. A two-dimensional Fourier transform pattern can be calculated in a short time. In FIG. 5C, the coordinate system (fx, fy) is the spatial frequency in the X direction and the Y direction, but in the present embodiment, the coordinates (fx, fy) are converted into coordinates on the projection pupil plane PLP. Shall. The Fourier transform pattern SP1 is a pattern in which spots 65A to 67A and 65B to 67B having a large amount of light are arranged symmetrically in the fx direction with respect to the center spot 64 (0th order light). This completes the preparation process.

  Note that the pitch of the periodic pattern (L & S pattern) that generated the first-order diffracted light can be calculated from the interval between the spot 64 (0th-order light) of the Fourier transform pattern SP1 and other spots 65A, 65B (first-order diffracted light). For this reason, in this embodiment, when the information of the Fourier transform pattern SP1 is known, the specific two-dimensional shape information of the device pattern DP1 of the reticle R is not necessary.

Next, an example of an operation for performing exposure by calculating the light amount distribution of the projection pupil plane PLP in the exposure apparatus EX using the calculation result of the preparation step will be described with reference to the flowchart of FIG. This operation is controlled by the main controller 14.
First, in step 112 of FIG. 9B, the main controller 14 of FIG. 2 inputs the information of the table TB1 created in step 106 from the host computer 12, and stores the input information of the table TB1 in the storage unit 52. To do. Further, main controller 14 inputs information of Fourier transform pattern SP1 of device pattern DP1 of reticle R from host computer 12, and stores the input information in storage unit 52 (step 114). Then, main controller 14 inputs information about the illumination condition (illumination pupil ILP shape and light amount distribution) of reticle R to be exposed from, for example, host computer 12, and stores the input information about illumination pupil ILP in storage unit 52. (Step 116). Note that the illumination condition of the reticle R may be recorded in advance in an exposure data file of the storage unit 52, for example.

  Then, in accordance with the operation command of main controller 14, operation unit 54 separates a plurality of partial Fourier transform patterns from Fourier transform pattern SP1 (FIG. 5C) of reticle R read from storage unit 52 (step S). 118). In this case, first, in the Fourier transform pattern SP1, two symmetric spots 65A and 65B that are closest to the spot 64 of the zero-order light are converted into the first-order diffracted light from the first periodic pattern as shown in FIG. Separate as spots. The first periodic pattern corresponds to the L & S pattern 62A of FIG. In addition, the distance between the central spot 64 and the spots 65A and 65B is FA1, and a spot whose interval is an integral multiple of FA1 with respect to the central spot 64 is separated as a spot of higher-order diffracted light from the same first periodic pattern. . In the example of FIG. 5C, since the distance from the center spot 64 to the third spots 67A and 67B on the left and right is three times FA1 (third-order diffracted light), the spots 67A and 67B are the spots 65A and 67B. It is separated as diffracted light from the first periodic pattern as in 65B (see FIG. 6A).

  Further, in the Fourier transform pattern SP1, two symmetric spots 66A and 66B that are next closest to the spot 64 of the zero-order light are converted into spots of the first-order diffracted light from the second periodic pattern as shown in FIG. As separate. The interval between the spot 64 and the spots 66A and 66B is FB1. The second periodic pattern corresponds to the L & S pattern 62B of FIG. The calculation unit 54 obtains the pitches p1 and p2 of the first and second periodic patterns from the intervals FA1 and FB1.

  Next, the calculation unit 54 separates the light amount of the zero-order light from the first and second periodic patterns from the light amount of the spot 64 of the zero-order light of the Fourier transform pattern SP1 in FIG. For this purpose, the intensities of the first-order diffracted light spots 65A and 65B shown in FIG. 6A and the zero-order light and the first-order diffracted light at the time of perpendicular incidence shown in FIG. The intensity of the spot 64a (see FIG. 6C) of the 0th-order light corresponding to the spots 65A and 65B is obtained using the value of the ratio of the square of the amplitude (the value at the pitch p1 of the curves A0 and A1). Furthermore, the intensity of the spots 66A and 66B of the first-order diffracted light in FIG. 6B and the ratio of the squares of the amplitudes of the zero-order light and the first-order diffracted light (values at the pitch p2 of the curves A0 and A1) in FIG. Is used to determine the intensity of the zero-order light spot 64b (see FIG. 6D) corresponding to the spots 66A and 66B.

  This separates the spot of the zeroth-order light of the first and second periodic patterns from the spot 64 of the zeroth-order light of the Fourier transform pattern SP1 according to the area ratio of the first and second periodic patterns. Means. As a result, the partial Fourier transform pattern SP1A including the spot 64a of the zeroth order light and the spots 65A and 65B of the first order diffracted light in FIG. 6C is separated as the Fourier transform pattern of the first periodic pattern, and FIG. ), The partial Fourier transform pattern SP1B composed of the spot 64b of the zeroth order light and the spots 66A and 66B of the first order diffracted light is separated as the Fourier transform pattern of the second periodic pattern.

  Next, the calculation unit 54 reads the illumination condition (illumination pupil ILP) of the reticle R from the storage unit 52, and divides the read illumination pupil ILP into a plurality of partial illumination pupils for each of a plurality of tilt angles in the X direction with respect to the reticle R. (Step 120). The illumination pupil ILP on the illumination pupil plane IPP when illuminating the reticle R is, as an example, as shown in FIG. 7A, two fan-shaped regions (hereinafter referred to as pupils) arranged symmetrically in the X direction with respect to the optical axis AX. It is assumed that the light quantity increases in 70A and 70B. The distance on the illumination pupil plane IPP is converted to the distance on the projection pupil plane PLP. In this case, since the tilt angle in the X direction with respect to the reticle R of the illumination light from that portion is defined by the interval in the ± X direction from the optical axis AX, the pupil regions 70A and 70B are as shown in FIG. In the X direction, it is divided into I partial pupil regions 70A (i) and 70B (i) (i = 1 to I) having a predetermined width (I is an integer of 2 or more). If the distance from the center optical axis AX of the partial pupil areas 70A (i) and 70B (i) (area where the amount of light of the partial illumination pupil increases) is xi, the tilt angle can be calculated from the distance xi. It is also possible to divide the pupil regions 70A and 70B into partial pupil regions having a radius ri around the optical axis AX.

  Then, the computing unit 54 uses the table TB1 for each i-th partial illumination pupil (partial pupil regions 70A (i) and 70B (i)), and the partial Fourier transform patterns shown in FIGS. 6C and 6D. The intensity of the diffracted light of SP1A and SP1B is corrected, and the partial Fourier transform patterns SP1A and SP1B after correction are convoluted with the partial pupil regions 70A (i) and 70B (i) to obtain the partial light quantity distribution (step) 122). Specifically, the first partial pupil regions 70A (1) and 70B (1) are as shown in FIG. 7C, and the X direction of the illumination light from the partial pupil regions 70A (1) and 70B (1) with respect to the reticle R Is assumed to be an angle θi shown in FIG. The difference between this angle θi (difference from 0 degree) and the angle θi and the maximum inclination angle θmax is, for example, k1: k2 (k1 and k2 are real numbers).

  At this time, in FIG. 4 which is data of the table TB1, the value of the point at which the values of the curve A0 and the curve B0 related to the 0th order light at the pitch p1 are interpolated with k1: k2 is C10 (i), the 1st order diffracted light. Assuming that the value of the point at which the curve A1 and the curve B1 are interpolated at k1: k2 is C11 (i), the values C10 (i) and C11 (i) are the partial pupil regions 70A (1) and 70B ( 1) The amplitudes of the 0th-order light and the 1st-order diffracted light generated from the illumination light (amplitude 1) emitted from the L & S pattern having the pitch p1. Similarly, in FIG. 4, the value of the point at which the values of the curve A0 and the curve B0 are interpolated by k1: k2 in the portion of the pitch p2 is C20 (i), and the value of the curve A1 and the curve B1 is k1: k2. Assuming that the value of the point to be interpolated is C21 (i), the values C20 (i) and C21 (i) are respectively emitted from the partial pupil regions 70A (1) and 70B (1) and enter the L & S pattern with the pitch p2. This is the amplitude of the 0th order light and the 1st order diffracted light generated from the illumination light (amplitude 1).

  Therefore, in the calculation unit 54, regarding the partial Fourier transform pattern SP1A in FIG. 6C, the values C10 () at the pitch p1 in FIG. The corrected intensity is obtained by multiplying the square of the ratio between i) and the value of the curve A0 and the square of the ratio between the value C11 (i) and the value of the curve A1. Further, regarding the partial Fourier transform pattern SP1B in FIG. 6D, the values C20 (i) and the curve A0 at the pitch p2 in FIG. 4 are respectively obtained as the intensities of the zeroth-order light spot 64b and the first-order diffracted light spots 66A and 66B. The corrected intensity is obtained by multiplying the square of the ratio with the square of the value and the square of the ratio between the value C21 (i) and the value of the curve A1. After that, by performing convolution of the partial Fourier transform patterns SP1A and SP1B whose intensity has been corrected and the partial pupil regions 70A (1) and 70B (1) in FIG. 7C, the first in FIG. Partial light quantity distribution 71 (1) is obtained. In FIG. 7D and the like, the dotted curve is the aperture 72 limited by the aperture stop AS of the projection optical system PL.

  Similarly, the second partial pupil regions 70A (2) and 70B (2) are as shown in FIG. 7E, and the illumination light from the partial pupil regions 70A (2) and 70B (2) in the X direction with respect to the reticle R is shown. The difference between the inclination angle (difference from 0 degree) and the inclination angle and the maximum inclination angle θmax is, for example, k3: k4 (k3 and k4 are real numbers). At this time, in FIG. 4 which is data of the table TB1, the value of the point at which the values of the curve A0 (A1) and the curve B0 (B1) regarding the 0th order light are interpolated at k3: k4 in the portion of the pitch p1 is C10 ( i) Assuming (C11 (i)), the values C10 (i) and C11 (i) are emitted from the partial pupil regions 70A (2) and 70B (2), respectively, and are incident on the L & S pattern having the pitch p1 ( This is the amplitude of the 0th order light and the 1st order diffracted light generated from the amplitude 1). Similarly, in FIG. 4, when the values of the curve A0 (A1) and the curve B0 (B1) are interpolated at k3: k4 at the pitch p2, the value of the point C20 (i) (C21 (i)) is assumed. , Values C20 (i) and C21 (i) are zero-order light generated from illumination light (amplitude 1) emitted from the partial pupil regions 70A (2) and 70B (2) and incident on the L & S pattern having the pitch p2, respectively. The amplitude of the first-order diffracted light. In addition, when the incident angle of illumination light is outside between 0 degree and the maximum inclination angle (second incident angle), the values of the two curves may be extrapolated.

  Therefore, by convolving the partial Fourier transform patterns SP1A and SP1B whose intensities are corrected using these values with the partial pupil regions 70A (2) and 70B (2) in FIG. 7E, FIG. A second partial light quantity distribution 71 (1) in (F) is obtained. Similarly, the convolution of the partial Fourier transform patterns SP1A and SP1B after intensity correction and the partial pupil regions 70A (i) and 70B (i) (i = 1 to I) up to the I-th in FIG. By doing so, partial light quantity distributions up to the I-th are obtained.

  Then, the calculation unit 54 integrates the I partial light quantity distributions obtained for each of the partial pupil regions 70A (i) and 70B (i) (i = 1 to I), and performs the projection shown in FIG. A light amount distribution 71 on the pupil plane PLP is obtained (step 124). Actually, in the light amount distribution 71, as shown in FIG. 8B, the light amount distribution 73 in which the light amount increases in the pupil regions 73A, 73B, 73C in the opening 72 becomes the light amount distribution on the projection pupil plane PLP. Information on the light quantity distribution 73 is supplied to the main controller 14. In the light quantity distribution 73, the partial light quantity distribution in the pupil regions 73A, 73B, and 73C changes depending on the three-dimensional structure of the device pattern DP1 of the reticle R.

  In the next step 126, the reticle R is loaded onto the reticle stage RST of FIG. 1 by a reticle loader system (not shown), and alignment is performed. Then, alignment is performed by loading an unexposed wafer W coated with a photoresist onto wafer stage WST (step 128). In main controller 14, in step 124, projection pupil plane PLP supplied from operation unit 54 is processed. A fluctuation amount of the optical characteristic (for example, aberration) of the projection optical system PL is calculated from the light amount distribution and the integrated irradiation energy measured by, for example, an integrator sensor (not shown), and the fluctuation amount is corrected by the imaging characteristic correction system 16 ( Step 130). In this state, the wafer W is scanned and exposed with an image of the pattern of the reticle R by the projection optical system PL (step 132). Thereafter, when the next wafer is exposed in step 136, the operation returns to step 128, and the next wafer loading, calculation and correction of the variation in the optical characteristics of the projection optical system PL, and wafer exposure are repeated.

As described above, according to the present embodiment, the light amount distribution on the projection pupil plane PLP of the diffracted light from the reticle R is calculated in consideration of the three-dimensional structure of the reticle R, and the optical of the projection optical system PL is calculated based on the calculation result. Since the fluctuation amount of the characteristic is corrected, even if the reticle R has a three-dimensional structure, the pattern image of the reticle R can always be exposed on the wafer W with high accuracy.
As described above, the exposure apparatus EX of the present embodiment calculates the light amount distribution (light intensity distribution) on the pupil plane (projection pupil plane) PLP of the projection optical system PL that receives light from the device pattern DP1 of the reticle R. A computing device 10 is provided. The calculation apparatus 10 generates 0th-order light and 1st-order diffracted light generated when the plurality of L & S patterns 62A and 62B having different periods in the device pattern DP1 are illuminated with light having different first and second incident angles, respectively. Information of the table TB1 in which the calculation result of the intensity information (amplitude) of the device is recorded, the Fourier transform pattern (Fourier spectrum) SP1 of the device pattern DP1 obtained by calculating the device pattern DP1 as a two-dimensional pattern, A storage unit 52 that stores information on the illumination pupil ILP of the illumination optical system ILS that illuminates the device pattern DP1 and a calculation unit 54 are provided. Information of the table TB1, the Fourier transform pattern SP1, and the illumination pupil ILP is input to the storage unit 52 in steps 112, 114, and 116, respectively.

  Then, the calculation unit 54 separates a plurality of partial Fourier transform patterns SP1A and SP1B generated by L & S patterns 62A and 62B (partial patterns) having different periods from the Fourier transform pattern SP1 (step 118), and sets the illumination pupil ILP. Divided into a plurality of partial illumination pupils 70A (i) and 70B (i), and corrected parts obtained by correcting the plurality of partial Fourier transform patterns SP1A and SP1B using the table TB1 for each partial illumination pupil A partial light amount distribution on the projection pupil plane PLP is obtained based on the Fourier transform pattern (steps 120 and 122), and a partial light amount distribution obtained for each partial illumination pupil is added to obtain a light amount distribution (step 124).

  According to the calculation device 10 of this embodiment or the light amount distribution calculation method using the calculation device 10, when the device pattern DP1 is a three-dimensional pattern formed on the thin film 58 having a certain thickness (d1 + d2), For example, the amount of light on the projection pupil plane PLP of the diffracted light generated from the device pattern DP1 is more efficient than when performing a strict electromagnetic field analysis and with higher accuracy than when the device pattern DP1 is calculated as a two-dimensional pattern. Distribution can be calculated.

The recording medium 51 stores a program that causes a computer including the storage unit 52 and the calculation unit 54 to execute the operations of steps 112 to 124. The main control device 14 reads out the program from the recording medium 51, and the computer. By executing this, the calculation of the light amount distribution of the present embodiment can be executed efficiently.
The exposure apparatus EX is an exposure apparatus that exposes the wafer W (substrate) through the pattern of the reticle R and the projection optical system PL with the illumination light EL from the illumination optical system ILS. A fluctuation amount of the aberration (optical characteristic) of the projection optical system PL is obtained based on the calculation device 10 and information on the light amount distribution of the light from the pattern of the reticle R on the projection pupil plane PLP obtained by the calculation device 10 (step 130). The main controller 20 corrects the fluctuation amount of the optical characteristic through the imaging characteristic correction system 16 (step 132).

  According to the exposure apparatus EX or the exposure method by the exposure apparatus EX, without actually measuring the light quantity distribution on the projection pupil plane PLP of the light from the pattern of the reticle R or the aberration fluctuation state of the projection optical system PL, It is possible to predict with high accuracy the aberration fluctuation amount of the projection optical system PL when the exposure using the reticle R is continued. Therefore, by correcting the predicted aberration fluctuation amount, even when the pattern of the reticle R is substantially a three-dimensional pattern, the pattern of the reticle R can be accurately applied to the wafer W without reducing the throughput. Can be exposed.

Note that the above-described embodiment can also be applied to the case where the pattern of the reticle R is not a thin film but is substantially formed of a transmittance distribution or a phase distribution.
In addition, when an L & S pattern having a pitch of 90 nm, for example, is actually exposed using the illumination pupil of FIG. 10A, the light amount distribution on the projection pupil plane PLP calculated by regarding the pattern as a two-dimensional pattern is shown in FIG. FIG. 10C shows the light amount distribution calculated by the calculation method of the above embodiment, assuming that the pattern is a three-dimensional pattern, and FIG. 10C shows the result of measuring the light amount distribution from the pattern by the measuring unit 20. As shown in FIG. FIG. 10 (D) and FIG. 10 (C) according to the calculation method of the present embodiment are in good agreement, and FIG. 10 (D) and FIG. It can be seen that the amount of light is relatively different in the inner part.

  In addition, the calculation method of the present embodiment uses a two-dimensional contact hole pattern such as pitches p3 and p4 in addition to the L & S pattern 62A as shown by the device pattern DP2 of the reticle R1 in FIG. The present invention can also be applied to cases including 63A and 63B. The Fourier transform pattern SP2 in this case is a two-dimensional pattern as shown in FIG. 11B, and the amplitudes of the zeroth-order light and the first-order diffracted light with respect to normal incidence and oblique incidence are previously obtained for a plurality of pitch contact hole patterns. By calculating (intensity) strictly, the light quantity distribution on the projection pupil plane PLP from the device pattern DP2 can be calculated with high accuracy and efficiency in consideration of the three-dimensional effect.

  FIG. 12 shows an L & S pattern 78A (line width 45 nm, 60 nm, 500 nm) with a duty ratio of 1: 1, an L & S pattern 78B (line width 45 nm, 60 nm) with a different duty ratio of + 10% and −10%, a two-dimensional positive type Contact hole pattern 78C (line width 45 nm, 60 nm, 500 nm), two-dimensional negative contact hole pattern 78D (line width 45 nm, 60 nm, 500 nm), and auxiliary pattern shapes A to C with a line width of about 40 nm. For different isolated patterns 78E, exact electromagnetic field analysis (bar graph 79A), calculation method considering the three-dimensional structure of the above embodiment (bar graph 79B), and calculation as a two-dimensional pattern (bar graph 79C), the intensity of the first-order diffracted light It is the ratio between IP1 and 0th-order light intensity IP0. The calculation method of this embodiment is in good agreement with the result of strict electromagnetic field analysis.

Further, FIG. 13 shows the light amount distribution on the projection pupil plane PLP of FIGS. 10B, 10C, and 10D when the line width of the L & S pattern is 45 nm. In FIG. 13, the distribution by strict electromagnetic field analysis is curves 76C0 and 76C1 (0th-order light and first-order diffracted light, the same applies hereinafter), and the distribution by the calculation method considering the three-dimensional structure of the above embodiment is curves 76B0 and 76B1. The distribution calculated as a dimensional pattern is curves 76A0 and 76A1, and the calculation method of this embodiment is in good agreement with the result of strict electromagnetic field analysis.
Further, the optical characteristics of the projection optical system that forms an image of a predetermined pattern illuminated with light from the illumination optical system may be calculated using the calculation method according to the above-described embodiment. Here, the optical characteristics can include, for example, the formation state of the aerial image by the projection optical system. In this case, the light quantity distribution of the light from the predetermined pattern on the pupil plane of the projection optical system is obtained using the calculation method according to the above-described embodiment, and the formation state of the aerial image is obtained by calculation using the obtained light quantity distribution. Note that the main controller 20 of the exposure apparatus EX according to the above-described embodiment can be regarded as an optical characteristic calculation apparatus that calculates the optical characteristics of the projection optical system.

  Further, when an electronic device (microdevice) such as a semiconductor device is manufactured using the exposure apparatus EX or the exposure method of the above embodiment, the electronic device has a function / performance design of the device as shown in FIG. Step 221 to be performed, Step 222 to manufacture a mask (reticle) based on this design step, Step 223 to manufacture a substrate (wafer) that is a base material of the device, the exposure apparatus EX, EXA or the exposure method of the above-described embodiment A process of exposing the mask pattern onto the substrate, a process of developing the exposed substrate, a substrate processing step 224 including heating (curing) and etching process of the developed substrate, a device assembly step (dicing process, bonding process, packaging process, etc.) 225) and inspection step 2 It is produced through a 6 or the like.

  In other words, the device manufacturing method includes the steps of exposing the substrate (wafer W) through the mask pattern using the exposure apparatus EX or the exposure method of the above embodiment, and processing the exposed substrate. (I.e., developing the resist on the substrate and forming a mask layer corresponding to the mask pattern on the surface of the substrate; and processing the surface of the substrate through the mask layer (heating, etching, etc.) ) Processing step).

According to this device manufacturing method, the image of the reticle pattern can be exposed onto the substrate with high accuracy and high throughput in the exposure apparatus or the exposure method, so that the electronic device can be efficiently manufactured with high accuracy.
Note that the light amount distribution calculation method and apparatus of the above embodiment can be applied to a stepper type exposure apparatus or the like.

In the device manufacturing method of the present embodiment, the method of manufacturing a semiconductor device has been particularly described. However, the device manufacturing method of the present embodiment can be applied to a semiconductor material such as a liquid crystal panel or a magnetic disk in addition to a device using a semiconductor material. The present invention can also be applied to the manufacture of devices using other materials.
In addition, this invention is not limited to the above-mentioned embodiment, A various structure can be taken in the range which does not deviate from the summary of this invention.

  EX ... exposure apparatus, ILS ... illumination optical system, R ... reticle, PL ... projection optical system, W ... wafer, DP1 ... device pattern, SP1 ... Fourier transform pattern, IPP ... illumination pupil plane, PLP ... projection pupil plane, 10 ... Light quantity distribution calculation device, 14 ... main control device, 20 ... light quantity distribution measurement unit, 51 ... recording medium 51, 52 ... storage unit, 54 ... calculation unit, 58 ... thin film, 60, 60A, 60B ... L & S pattern (line) -And space pattern), 73 ... Light intensity distribution

As the illumination light IL, for example, ArF excimer laser light (wavelength 193 nm) is used. As illumination light, KrF excimer laser light (wavelength 248 nm), harmonics of a YAG laser or a solid-state laser (semiconductor laser, etc.), or a bright line (i-line etc.) of a mercury lamp can be used. The illumination optical system ILS is linearly polarized or non-polarized in a predetermined direction supplied from the light source 30 as indicated by a dotted line and as disclosed in, for example, US Patent Application Publication No. 2003/0025890. A mirror MR1 that reflects illumination light IL for exposure such as polarized light, a spatial light modulator 32 that reflects the reflected light by an array of multiple tilt angle variable mirror elements, and collects light from the array of mirror elements It has a condensing optical system 33 and a mirror MR2 that reflect, and a fly-eye lens 34 (optical integrator) that forms a surface light source (illumination pupil) on the exit surface from the reflected light. In the present embodiment, the exit surface of the fly-eye lens 34 is the illumination pupil plane IPP.

The recording medium 51 stores a program that causes a computer including the storage unit 52 and the calculation unit 54 to execute the operations of steps 112 to 124. The main control device 14 reads out the program from the recording medium 51, and the computer. By executing this, the calculation of the light amount distribution of the present embodiment can be executed efficiently.
The exposure apparatus EX is an exposure apparatus that exposes the wafer W (substrate) through the pattern of the reticle R and the projection optical system PL with the illumination light IL from the illumination optical system ILS. A fluctuation amount of the aberration (optical characteristic) of the projection optical system PL is obtained based on the calculation device 10 and information on the light amount distribution of the light from the pattern of the reticle R on the projection pupil plane PLP obtained by the calculation device 10 (step 130). The main controller 14 corrects the fluctuation amount of the optical characteristic via the imaging characteristic correction system 16 (step 132).

Claims (19)

A calculation method for calculating a light amount distribution in a pupil plane of a projection optical system that receives light from a predetermined pattern,
Intensity information of the first and second diffracted lights of different orders generated when a plurality of periodic patterns having different periods among the predetermined patterns are illuminated with lights having different first and second incident angles. Enter the information of the table where the calculation result of
Inputting Fourier transform pattern information of the predetermined pattern obtained by calculating the predetermined pattern as a two-dimensional pattern;
Inputting information of an illumination pupil of an illumination optical system that illuminates the predetermined pattern;
Using the information of the Fourier transform pattern, separating a plurality of partial Fourier transform patterns generated by the partial patterns having different periods from the Fourier transform pattern;
Using the information of the illumination pupil, the illumination pupil is divided into a plurality of partial illumination pupils, and the corrected partial Fourier transform pattern obtained by correcting the plurality of partial Fourier transform patterns using the table for each partial illumination pupil Obtaining a partial light amount distribution in the pupil plane of the projection optical system based on a partial Fourier transform pattern;
Adding the partial light amount distribution obtained for each partial illumination pupil to obtain a light amount distribution;
Calculation method of light quantity distribution including   The calculation method according to claim 1, wherein the first and second incident angles used when creating the table are an angle of vertical incidence and a maximum inclination angle of light that can be incident on the predetermined pattern, respectively.   The calculation method according to claim 1, wherein the first and second diffracted lights whose intensities are recorded on the table are zero-order light and first-order light. Separating a plurality of partial Fourier transform patterns generated by partial patterns having different periods from the Fourier transform pattern,
Selecting a plurality of first-order diffracted lights having different distances from zero-order light in the Fourier transform pattern as diffracted lights from the plurality of partial patterns;
Obtaining the intensity of the 0th-order light from the plurality of partial patterns out of the intensity of the 0th-order light based on the respective intensities of the plurality of first-order diffracted lights;
The calculation method according to claim 3. Selecting a plurality of first-order diffracted lights having different distances from zero-order light in the Fourier transform pattern as diffracted lights from the plurality of partial patterns,
5. The calculation method according to claim 4, further comprising: selecting a plurality of diffracted lights whose distance from the 0th order light is an integral multiple of each other in the Fourier transform pattern as diffracted lights from the same partial pattern. For each partial illumination pupil, correcting the plurality of partial Fourier transform patterns using the table to obtain the corrected partial Fourier transform pattern,
Intensity information of the first and second diffracted lights recorded with respect to the first and second incident angles of the table in accordance with an incident angle of light with respect to the pattern obtained corresponding to the partial illumination pupil. 6. The intensity of the first and the second diffracted light in the partial Fourier transform pattern is corrected based on the intensity obtained by interpolating or extrapolating. Calculation method. In a calculation method of optical characteristics of a projection optical system that forms an image of a predetermined pattern illuminated with light from an illumination optical system,
Obtaining the light amount distribution of the light from the predetermined pattern on the pupil plane of the projection optical system using the light amount distribution calculating method according to claim 1;
Obtaining optical characteristics of the projection optical system using information on a light amount distribution on a pupil plane of the projection optical system;
Calculation method including In an exposure method of illuminating a predetermined pattern with light from an illumination optical system and exposing the substrate with the light through the predetermined pattern and a projection optical system,
Obtaining the light amount distribution of the light from the predetermined pattern on the pupil plane of the projection optical system using the light amount distribution calculating method according to claim 1;
Obtaining a variation amount of the optical characteristics of the projection optical system based on information on a light amount distribution on a pupil plane of the projection optical system;
Correcting the obtained variation amount of the optical characteristics;
An exposure method comprising: A calculation device for calculating a light amount distribution in a pupil plane of a projection optical system that receives light from a predetermined pattern,
Intensity information of the first and second diffracted lights of different orders generated when a plurality of periodic patterns having different periods among the predetermined patterns are illuminated with lights having different first and second incident angles. Information of the table in which the calculation results of the above are recorded, information on the Fourier transform pattern of the predetermined pattern obtained by calculating the predetermined pattern as a two-dimensional pattern, and an illumination optical system for illuminating the predetermined pattern A storage device for storing illumination pupil information;
Separating a plurality of partial Fourier transform patterns generated by partial patterns having different periods from the Fourier transform pattern using the information of the Fourier transform pattern, and using the information of the illumination pupil, Dividing into partial illumination pupils, and for each partial illumination pupil, based on corrected partial Fourier transform patterns obtained by correcting the plurality of partial Fourier transform patterns using the table, on the pupil plane of the projection optical system An apparatus for calculating a light quantity distribution, comprising: an arithmetic unit that obtains a partial light quantity distribution and calculates the light quantity distribution by adding the partial light quantity distributions obtained for each of the partial illumination pupils.   10. The calculation apparatus according to claim 9, wherein the first and second incident angles used when creating the table are a vertical incident angle and a maximum inclination angle of light incident on the predetermined pattern, respectively. .   The calculation device according to claim 9 or 10, wherein the first and second diffracted lights whose intensities are recorded on the table are zero-order light and first-order light. The arithmetic unit is:
In order to separate a plurality of partial Fourier transform patterns generated by partial patterns having different periods from the Fourier transform pattern,
A plurality of first-order diffracted lights having different distances from zero-order light in the Fourier transform pattern are selected as diffracted lights from the plurality of partial patterns;
The calculation device according to claim 11, wherein, based on the respective intensities of the plurality of first-order diffracted lights, out of the zero-order light intensities, the zero-order light intensities from the plurality of partial patterns are obtained. The arithmetic unit is:
In order to select a plurality of first-order diffracted lights having different distances from zero-order light in the Fourier transform pattern as diffracted lights from the plurality of partial patterns,
The calculation apparatus according to claim 12, wherein a plurality of diffracted lights whose distances from the 0th order light are integer multiples of each other in the Fourier transform pattern are selected as diffracted lights from the same partial pattern. The arithmetic unit is:
In order to obtain the corrected partial Fourier transform pattern by correcting the plurality of partial Fourier transform patterns using the table for each partial illumination pupil,
Intensity information of the first and second diffracted lights recorded with respect to the first and second incident angles of the table in accordance with an incident angle of light with respect to the pattern obtained corresponding to the partial illumination pupil. 14. The calculation device according to claim 9, wherein the first and second diffracted light in the partial Fourier transform pattern is corrected based on an intensity obtained by interpolating or extrapolating. . In a calculation device for optical characteristics of a projection optical system that forms an image of a predetermined pattern illuminated with light from an illumination optical system,
A light amount distribution calculating device according to any one of claims 9 to 14, comprising:
The calculation apparatus includes an optical characteristic calculation apparatus that calculates optical characteristics of the projection optical system using information on a light amount distribution of light from the predetermined pattern on the pupil plane of the projection optical system determined by the arithmetic unit. . In an exposure apparatus that illuminates a predetermined pattern with light from an illumination optical system and exposes the substrate with the light through the predetermined pattern and the projection optical system,
The light quantity distribution calculating device according to any one of claims 9 to 14,
A variation amount of the optical characteristic of the projection optical system is obtained based on information on a light amount distribution of light from the predetermined pattern on the pupil plane of the projection optical system obtained by the calculation device, and the variation amount of the optical characteristic is corrected. A control device;
An exposure apparatus comprising: Forming a pattern of a photosensitive layer on a substrate using the exposure method according to claim 8;
Processing the substrate on which the pattern is formed;
A device manufacturing method including: Forming a pattern of a photosensitive layer on a substrate using the exposure apparatus according to claim 16;
Processing the substrate on which the pattern is formed;
A device manufacturing method including:   A program for causing a computer to execute the processing of the calculation method according to any one of claims 1 to 6 for calculating a light amount distribution on a pupil plane of a projection optical system that receives light from a predetermined pattern is recorded. Computer-readable recording medium.

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