JP2011187597A - Illuminating light source evaluating method, illuminating light source setting method, exposure method and device manufacturing method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately evaluate a light source shape by using a deviation of a measurement result of the light source shape from a target. <P>SOLUTION: The shape (light source shape) of an illuminating light source is set (S206) by controlling a spatial optical modulator 3S based upon designs of the illuminating light source and a mask pattern obtained through optimization calculation for optimizing the illuminating light source. The light source shape is measured (S208) by projecting illuminating light generated by the illuminating light source on a wafer through an illuminating optical system. The shape of the illuminating light source is evaluated (S214) by using the deviation of the measurement result of the light source shape from the target. Further, the shape of the illuminating light source is optimized based upon the evaluated shape of the illuminating light source. Consequently, suitable settings of the shape of the illuminating light source for a pattern are made. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an illumination light source evaluation method, an illumination light source setting method, an exposure method, a device manufacturing method, and a program, and more specifically, an illumination light source evaluation method for evaluating the shape of an illumination light source for forming a pattern on an object. An illumination light source setting method for setting an illumination light source using the illumination light source evaluation method, and a pattern is formed on an object by exposure with illumination light generated by the illumination light source set using the illumination light source setting method The present invention relates to an exposure method, a device manufacturing method using the exposure method, and a program for causing a processing apparatus to execute the illumination light source evaluation method or the illumination light source setting method.

With the miniaturization of device patterns, high resolution has been required for projection exposure apparatuses such as so-called steppers or so-called scanning steppers (also called scanners) used in the manufacture of semiconductor elements and the like. . The resolution R is expressed by the Rayleigh equation, that is, R = k ₁ (λ / NA). Here, λ is the wavelength of the light source (illumination light), NA is the numerical aperture of the projection optical system, and k ₁ is a process factor determined by the resolution and / or process controllability of the resist. For this reason, conventionally, the resolution has been improved by shortening the wavelength λ of the illumination light and increasing the numerical aperture of the projection optical system (higher NA). However, the shortening of the exposure wavelength is accompanied by difficulties in the development of light sources and glass materials, for example, and the increase in NA results in a decrease in the depth of focus (DOF) of the projection optical system, thereby improving the imaging performance (imaging characteristics). In order to make it worse, it is not possible to push the increase in NA.

For the reasons described above, it has not been possible to keep up with miniaturization of circuit patterns and sizes only by shortening the wavelength λ of the illumination light and increasing the numerical aperture of the projection optical system (higher NA). Therefore, modified illumination techniques such as annular illumination, and the introduction of light survival techniques such as phase-shift masks, efforts lithographic performance improvement by process development techniques such as materials and thin and multilayer in resist technology (Low K ₁ of) Has been made.

In recent years, an exposure apparatus that employs a local immersion exposure technique has been put into practical use as a means for achieving a higher NA. In the immersion exposure apparatus, of course, the wavelength λ of illumination light is shortened. However, there is a limit to the increase in NA, and Low ₁ has become indispensable. In recent Lowk ₁ , not only super-resolution technology such as modified illumination and phase shift technology is used, but also optical system errors such as aberration and the fidelity of the pattern when the reticle pattern is transferred onto the wafer. It has also become necessary to consider optical proximity correction (OPC) that corrects the deterioration with a reticle pattern. However, Lowk ₁ causes a decrease in the contrast of the pattern image, and thus this point needs to be taken into consideration.

Against this backdrop, SMO (Source and Mask Optimization), which simultaneously optimizes the mask (reticle) pattern and illumination light source using an optical model, has been recently developed to provide an optical imaging solution that can be mass-produced at low k ₁ values. Attracted attention. SMO is disclosed in, for example, Patent Document 1. The light source intensity distribution output by the SMO is realized by a spatial light modulator (SLM) as disclosed in, for example, Patent Document 2.

  However, there is a difference between the target light source intensity distribution and the actual light source intensity distribution due to various errors. Due to this deviation, the imaging performance, in particular, the optical proximity effect (OPE: Optical proximity effect) results different from the target value (results in an OPE error). In the conventional imaging optical system, parameters for correcting the OPE error are relatively simple parameters such as NA of the projection optical system, illumination σ, and annular ratio. Therefore, OPE matching itself can be performed relatively easily.

  However, in order to accurately perform OPE matching of a complex illumination intensity distribution such as an SMO solution with a highly flexible parameter called SLM, the intensity distribution set by the SLM with respect to the intensity distribution obtained as the SMO solution may be used. It is assumed that the degree of coincidence is accurately evaluated.

US Pat. No. 6,563,566 US Patent Application Publication No. 2009/0097094

  According to the first aspect of the present invention, there is provided an illumination light source evaluation method for evaluating an illumination light source that generates illumination light for forming a pattern on an object, the result of optimization calculation for optimizing the illumination light source The shape of the illumination light source in the optical system is actually set with the shape of the illumination light source obtained as a target, and the illumination light generated by the set illumination light source is received on a predetermined surface to receive the optical system Measuring the intensity distribution of the illumination light on the pupil plane or its conjugate plane; an index value of the measured intensity distribution, and an index of the intensity distribution of the illumination light corresponding to the target shape An illumination light source evaluation method including: evaluating a degree of coincidence of the set shape of the illumination light source with respect to the target shape based on a predetermined evaluation criterion regarding a value.

  According to this, the setting for the target shape based on a predetermined evaluation criterion regarding the index value of the measured intensity distribution and the index value of the intensity distribution of illumination light corresponding to the target shape The degree of coincidence of the shape of the illumination light source is evaluated. That is, since the degree of coincidence of the set shape of the illumination light source with respect to the target shape is evaluated based on an objective evaluation criterion, accurate evaluation is possible.

  According to the 2nd aspect of this invention, the program which makes a processing apparatus perform the illumination light source evaluation method of this invention is provided.

  According to a third aspect of the present invention, there is provided an illumination light source setting method for setting a shape of an illumination light source for forming a pattern on an object, wherein the illumination light source evaluation method of the present invention is used to There is provided an illumination light source setting method including: evaluating a shape; and adjusting the light source such that a deviation of the measured light source shape from the target falls within an allowable range based on the evaluation result Is done.

  According to this, it becomes possible to set the optimum light source shape obtained as a result of the optimization calculation for optimizing the illumination light source.

  According to the 4th aspect of this invention, the program which makes a processing apparatus perform the illumination light source setting method of this invention is provided.

  According to a fifth aspect of the present invention, there is provided an exposure method for irradiating illumination light from the illumination light source having a light source shape set by the illumination light source setting method of the present invention to form the pattern on an object. Is done.

  According to this, it becomes possible to form a pattern on an object with high resolution and high accuracy.

  According to a sixth aspect of the present invention, there is provided a device manufacturing method comprising: forming the pattern on an object using the exposure method of the present invention; and developing the object on which the pattern is formed. Is provided.

It is a figure which shows schematic structure of the exposure apparatus which concerns on 1st Embodiment. It is a figure which shows the structure of the spatial light modulation unit which comprises the illumination system of FIG. It is a figure which shows an example of a structure of the luminance distribution measuring device which measures a pupil luminance distribution. It is a figure which shows the relationship between the image surface (image surface coordinate system) of a projection optical system, and a pupil surface (pupil surface coordinate system). It is a figure for demonstrating distortion modulation. It is a figure which shows the outline | summary of the optimal design procedure of the light source shape (pupil luminance distribution) and reticle pattern by SMO. 7A is a target pattern input to the SMO, FIG. 7B is a light source shape SMO solution, and FIGS. 7C and 7D are mask patterns (transmission distribution and phase shift distribution, respectively). FIGS. 7E to 7G are views showing the performance of the SMO solution (focus dependence of the projected image). 8A shows the SMO solution of the light source shape (pupil luminance distribution), and FIG. 8B shows the detection result of the line width of the test pattern transferred onto the wafer with respect to the SMO solution of the light source shape (pupil luminance distribution). FIG. 8C shows the light source shape (pupil luminance distribution) reproduced by the spatial light modulation unit (spatial light modulator) based on the SMO solution, and FIG. 8D shows the reproduced light source shape (pupil luminance distribution). FIG. 6 is a diagram showing a detection result of a line width of a test pattern transferred onto a wafer. It is a figure which shows the result of OPE matching. It is a flowchart which shows the schematic procedure of OPE matching of the SMO solution of a light source shape (pupil luminance distribution). It is a table | surface which shows the Zernike polynomial (Zernike function) which is a 1st model employ | adopted in OPE matching. It is a table | surface which shows the distortion function which is a 2nd model employ | adopted in OPE matching. It is a flowchart which shows the schematic procedure of the OPE matching of the SMO solution of the light source shape (pupil luminance distribution) in 2nd Embodiment. It is a flowchart which shows the schematic procedure of the OPE matching of the SMO solution of the light source shape (pupil luminance distribution) in 3rd Embodiment. 15A shows the SMO solution of the light source shape (pupil luminance distribution), FIG. 15B shows the process window obtained for the SMO solution of the light source shape (pupil luminance distribution), and FIG. 15C shows the SMO solution. The light source shape (pupil luminance distribution) reproduced by the spatial light modulation unit (spatial light modulator) based on Fig. 15D shows the process window obtained for the reproduced light source shape (pupil luminance distribution). FIG.

<< First Embodiment >>
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows a schematic configuration of an exposure apparatus 100 according to the first embodiment. The exposure apparatus 100 is a step-and-scan projection exposure apparatus, a so-called scanner. As will be described later, in the present embodiment, a projection optical system PL is provided. In the following description, a reticle and wafer are arranged in a direction perpendicular to the Z-axis direction parallel to the optical axis AX of the projection optical system PL and in a plane perpendicular to the Z-axis direction. And the direction perpendicular to the Z and Y axes is the X axis direction, and the rotation (tilt) directions around the X, Y, and Z axes are θx, θy, And the θz direction will be described.

  The exposure apparatus 100 includes an illumination system IOP, a reticle stage RST that holds a reticle R, a projection unit PU that projects a pattern image formed on the reticle R onto a wafer W coated with a sensitive agent (resist), and a wafer W. A wafer stage WST to be held and a control system for these are provided.

  The illumination system IOP includes a light source 1, a beam expander 2, a spatial light modulation unit 3, a relay optical system 4, and a fly-eye lens 5 as an optical integrator that are sequentially arranged on the optical path of the light beam LB emitted from the light source 1. A condenser optical system 6, an illumination field stop (reticle blind) 7, an imaging optical system 8, and an illumination optical system including a bending mirror 9.

  As an example of the light source 1, an ArF excimer laser (output wavelength 193 nm) is used. The light beam LB emitted from the light source 1 has, for example, a rectangular cross-sectional shape that is long on the X axis.

  The beam expander 2 includes a concave lens 2a and a convex lens 2b. The concave lens 2a has a negative refractive power, and the convex lens 2b has a positive refractive power.

  The spatial light modulation unit 3 includes a so-called K prism (hereinafter simply referred to as a prism) 3P and a reflective spatial light modulator (SLM: Spatial Light Modulator) disposed on the upper surface (+ Z side surface) of the prism 3P. ) 3S. The prism 3P is made of optical glass such as fluorite or quartz glass.

  As shown in an enlarged view in FIG. 2, on the lower surface of the prism 3P, that is, on the side opposite to the spatial light modulator 3S, an incident surface (−Y side surface) and an exit surface (+ Y) parallel to the XZ plane in FIG. V-shaped surfaces (surfaces recessed in a wedge shape) made of surfaces PS1 and PS2 that intersect each other at 60 degrees and intersect each other at 120 degrees are formed. The back surfaces of the surfaces PS1 and PS2 (inner surfaces of the prism 3P) function as reflecting surfaces R1 and R2, respectively.

  The reflecting surface R1 reflects light parallel to the Y axis, which is perpendicularly incident on the incident surface of the prism 3P from the beam expander 2, in the direction of the spatial light modulator 3S. The reflected light beam LB reaches the spatial light modulator 3S via the upper surface of the prism 3P, and is reflected toward the reflection surface R2 by the spatial light modulator 3S as will be described later. The reflecting surface R2 of the prism 3P reflects the light that has arrived from the spatial light modulator 3S via the upper surface of the prism 3P and emits it to the relay optical system 4 side.

  The spatial light modulator 3S is a reflective spatial light modulator. The spatial light modulator means an element that processes, displays, and erases spatial information such as an image or patterned data by two-dimensionally controlling the amplitude, phase, or traveling direction of incident light. As the spatial light modulator 3S of the present embodiment, a movable multi-mirror array having a large number of minute mirror elements SE arranged on a two-dimensional (XY) plane is used. The spatial light modulator 3S includes a large number of mirror elements. In FIG. 2, only the mirror elements SEa, SEb, SEc, and SEd are shown. The spatial light modulator 3S continuously tilts (rotates) a large number of mirror elements SE and the large number of mirror elements SE within a predetermined range around two orthogonal axes (for example, the X axis and the Y axis) in the XY plane. And the same number of driving units. The drive unit includes, for example, a support column that supports the center of the back surface (the surface on the + Z side, that is, the surface opposite to the reflection surface) of the mirror element SE, a substrate on which the support column is fixed, and four electrodes provided on the substrate. And four electrodes (not shown) provided on the back surface of the mirror element SE so as to face the electrodes. The detailed configuration of the spatial light modulator similar to the spatial light modulator 3S is disclosed in, for example, US Patent Application Publication No. 2009/0097094.

  Returning to FIG. 1, the fly-eye lens 5 is a set of a large number of microlens elements having positive refractive power arranged densely in the direction perpendicular to the light beam LB. As the fly-eye lens 5, for example, a cylindrical micro fly-eye lens disclosed in US Pat. No. 6,913,373 can be employed.

  According to the illumination system IOP of the present embodiment, the light beam LB emitted from the light source 1 is incident on the beam expander 2 and passes through the beam expander 2 so that its cross section is enlarged, and a predetermined rectangular cross section is formed. It is shaped into a light beam. The light beam LB shaped by the beam expander 2 enters the spatial light modulation unit 3.

  For example, as shown in FIG. 2, four parallel light beams L1 to L4 aligned in the Z-axis direction in the light beam LB enter the inside from the incident surface of the prism 3P and are spatially modulated by the reflecting surface R1. Reflected parallel to each other toward the container 3S. The light beams L1 to L4 are incident on the reflecting surfaces of different mirror elements SEa, SEb, SEc, and SEd arranged in the Y-axis direction among the plurality of mirror elements SE. Here, the mirror elements SEa, SEb, SEc, and SEd are independently tilted by respective driving units (not shown). For this reason, the light rays L1 to L4 are reflected toward the reflecting surface R2 in different directions. Then, the light beams L1 to L4 (light beam LB) are reflected by the reflecting surface R2 and emitted to the outside of the prism 3P. Here, the air-converted optical path lengths of the light beams L1 to L4 from the −Y side surface (incident surface) to the + Y side surface (outgoing surface) of the prism 3P correspond to the air-converted optical path length when the prism 3P is not provided. Is set equal to Here, the air-converted optical path length is an optical path length L / n obtained by converting an optical path length (L) of light in the medium (refractive index n) into an optical path length in the air (refractive index 1).

  Light rays L1 to L4 (light beam LB) emitted to the outside of the prism 3P are aligned in parallel to the Y axis via the relay optical system 4 and are incident on the fly-eye lens 5 disposed behind the relay optical system 4. To do. The light beams L1 to L4 (light beam LB) are divided (wavefront division) into a plurality (a large number) by the fly-eye lens 5 (a large number of lens elements). Thereby, a secondary light source (surface light source, that is, an illumination light source) composed of a plurality of light source images is formed on the rear focal plane LPP of the fly-eye lens 5 that coincides with the pupil plane (illumination pupil plane) of the illumination optical system. .

  FIG. 2 schematically shows light intensity distributions SP1 to SP4 corresponding to the light beams L1 to L4 on the rear focal plane LPP of the fly-eye lens 5. Thus, in the present embodiment, the light intensity distribution (also referred to as luminance distribution or light source shape) of the secondary light source (illumination light source) is freely set by the spatial light modulator 3S. As the spatial light modulator, the above-described reflective active spatial light modulator, or a transmissive or reflective diffractive optical element as an inactive spatial light modulator can be used. When such an inactive spatial light modulator is used, the secondary light source is controlled by controlling the position and orientation of at least some of the optical members (lens, prism member, etc.) constituting the relay optical system 4. The light intensity distribution of (illumination light source) can be variably set. Further, as a diffractive optical element, for example, Japanese Patent Laid-Open No. 2001-217188 and US Pat. No. 6,671,035 corresponding thereto and Japanese Patent Laid-Open No. 2006-005319 and US Pat. No. 7,265 corresponding thereto are disclosed. , 816, the light intensity distribution of the secondary light source (illumination light source) may be variably set by controlling the position of a diffractive optical element having a plurality of sections. Further, in addition to the above-mentioned active or inactive spatial light modulator, a movable illumination aperture disclosed in, for example, Japanese Patent Laid-Open No. 2000-58441 and US Pat. No. 6,452,662 corresponding thereto is disclosed. The light intensity distribution of the secondary light source (illumination light source) may be variably set using a diaphragm.

  In the present embodiment, the secondary light source formed by the fly-eye lens 5 is used as an illumination light source, and the reticle R held on a reticle stage RST described later is Koehler illuminated. Therefore, the surface on which the secondary light source is formed is a conjugate surface with respect to the surface of the aperture stop 41 (aperture stop surface) of the projection optical system PL, and is called a pupil plane (illumination pupil plane) of the illumination optical system. Further, the irradiated surface (the surface on which the reticle R is disposed or the surface on which the wafer W is disposed) is an optical Fourier transform surface with respect to the illumination pupil plane. When the number of wavefront divisions by the fly-eye lens 5 is relatively large, the overall light intensity distribution formed on the entrance surface of the fly-eye lens 5 and the overall light intensity distribution (pupil intensity distribution) of the entire secondary light source. ) And a high correlation. For this reason, the light intensity distribution on the incident surface of the fly-eye lens 5 and the surface optically conjugate with the incident surface can also be referred to as the light intensity distribution (luminance distribution or light source shape) of the secondary light source (illumination light source). .

  Returning to FIG. 1, the light beam LB emitted from the fly-eye lens 5 is condensed by the condenser optical system 6, and further, the illumination field stop 7, the imaging optical system 8, the bending mirror 9, etc. (hereinafter, the condenser optical system). 6 to the bending mirror 9 are collectively referred to as a light transmission optical system 10) and emitted from the illumination system IOP. As shown in FIG. 1, the emitted light beam LB is irradiated onto the reticle R as illumination light IL. Here, by shaping the light beam LB (illumination light IL) by the illumination field stop 7, a part (illumination area) of the pattern surface of the reticle R is illuminated.

  Reticle stage RST is arranged below (−Z side) illumination system IOP. On reticle stage RST, reticle R is fixed, for example, by vacuum suction. The reticle stage RST can be finely driven in a horizontal plane (XY plane) by a reticle stage drive system (not shown) including a linear motor, for example, and can be driven within a predetermined stroke range in the scanning direction (Y-axis direction). It has become.

  Position information of the reticle stage RST in the XY plane (including rotation information in the θz direction) is transferred to a movable mirror 12 (or an end surface of the reticle stage RST) by a reticle laser interferometer (hereinafter referred to as “reticle interferometer”) 14. For example, it is always detected with a resolution of about 0.25 nm through the formed reflection surface. Measurement information of reticle interferometer 14 is supplied to main controller 20.

  Projection optical system PL is arranged below reticle stage RST (−Z side). As the projection optical system PL, for example, a refractive optical system including a plurality of optical elements (lens elements) arranged along the optical axis AX is used. The projection optical system PL is, for example, both-side telecentric and has a predetermined projection magnification (for example, 1/4 times, 1/5 times, or 1/8 times). Therefore, as described above, when the reticle R is illuminated by the illumination light IL from the illumination system IOP, illumination on the pattern surface of the reticle R (the first surface of the projection optical system, the object surface) via the projection optical system PL. A reduced image of the pattern in the region (a reduced image of a part of the pattern) is projected onto the exposure region IA on the wafer W (second surface of the projection optical system, image surface) coated with a resist (sensitive agent). .

  Among a plurality of lens elements constituting the projection optical system PL, a plurality of lens elements (not shown) on the object plane side (reticle R side) are controlled by an imaging performance correction controller 48 under the main controller 20. For example, it is a movable lens that can be driven in the Z-axis direction, which is the optical axis direction of the projection optical system PL, and in the tilt direction with respect to the XY plane (that is, the θx and θy directions). An aperture stop 41 that continuously changes the numerical aperture (NA) within a predetermined range is provided in the vicinity of the pupil plane of the projection optical system PL. As the aperture stop 41, for example, a so-called iris stop is used. The aperture stop 41 is controlled by the main controller 20 via the imaging performance correction controller 48.

  Wafer stage WST is driven on stage base 22 with a predetermined stroke in the X-axis direction and Y-axis direction by stage drive system 24 including a linear motor and the like, and in Z-axis direction, θx direction, θy direction, and θz direction. It is driven minutely. On wafer stage WST, wafer W is held by vacuum suction or the like via a wafer holder (not shown).

  Position information (including rotation information (yaw amount (rotation amount in θz direction), pitching amount (rotation amount in θx direction) and rolling amount (rotation amount in θy direction)) of wafer stage WST in the XY plane) is a laser. An interferometer system (hereinafter abbreviated as “interferometer system”) 18 always detects with a resolution of about 0.25 nm, for example, via a movable mirror 16 (or a reflecting surface formed on the end surface of wafer stage WST). The Measurement information of the interferometer system 18 is supplied to the main controller 20.

  Further, the position and the inclination of the surface of the wafer W in the Z-axis direction are such that an imaging light beam for forming images of many pinholes or slits toward the imaging surface of the projection optical system PL with respect to the optical axis AX. It is measured by a focal position detection system having an irradiation system 60a that irradiates from an oblique direction and a light receiving system 60b that receives a reflected light beam of the imaging light beam on the surface of the wafer W. As the focal position detection system (60a, 60b), one having the same configuration as the oblique incidence type multipoint focal position detection system disclosed in, for example, US Pat. No. 5,448,332 is used.

  On the wafer stage WST, a reference plate FP whose surface is flush with the surface of the wafer W is fixed. On the surface of the reference plate FP, a reference mark used for baseline measurement of the alignment system AS, a pair of reference marks detected by a reticle alignment system described later, and the like are formed.

  Further, the wafer stage WST is provided with a luminance distribution measuring device 80 that measures the pupil luminance distribution on-body. As shown in FIG. 3, the luminance distribution measuring device 80 includes a cover glass 80a, a condensing lens 80b, a light receiving unit 80c, and the like.

  The upper surface of cover glass 80a is set equal to the image plane position of projection optical system PL, that is, the surface position of wafer W placed on wafer stage WST. Here, on the upper surface, a light shielding film having a circular opening (pinhole) in the center is formed by vapor deposition of a metal such as chromium. This light shielding film blocks unnecessary light from entering the light receiving unit 80c when measuring the pupil luminance distribution. The cover glass 80a (pinhole) and the light receiving unit 80c are disposed at the front and rear focal positions of the condenser lens 80b, respectively. That is, the light receiving surface of the light receiving unit 80c is arranged at a position optically conjugate with the position of the aperture stop 41 of the projection optical system PL (that is, the pupil plane of the projection optical system PL and the pupil plane of the illumination system IOP). The light receiving unit 80c includes a light receiving element including a two-dimensional CCD and the like, and an electric circuit such as a charge transfer control circuit. The measurement data from the light receiving unit 80c is sent to the main controller 20.

  In the luminance distribution measuring device 80 having the above-described configuration, a part of the illumination light IL emitted from the projection optical system PL passes through the pinhole of the cover glass 80a, is condensed by the condenser lens 80b, and is collected by the light receiving unit 80c. Incident on the light receiving surface. Here, the intensity distribution of the illumination light IL at the aperture stop 41 of the projection optical system PL is reproduced on the light receiving surface of the light receiving unit 80c. That is, the light distribution unit 80c measures the intensity distribution on a part of the aperture stop 41 of the illumination light IL that passes through the pinhole of the cover glass 80a. Here, since the position of the aperture stop 41 is optically conjugate with the positions of the pupil plane of the projection optical system PL and the pupil plane of the illumination system IOP, measuring the intensity distribution of the illumination light IL measures the pupil luminance distribution. Is equivalent to

  An alignment mark (not shown) having a known positional relationship with the pinhole is provided on the upper surface of the cover glass 80a. The alignment mark is used to calibrate the position of the pinhole on the stage coordinate system, that is, the position of the luminance distribution measuring device 80.

  By moving the wafer stage WST (that is, the luminance distribution measuring device 80) in the XY two-dimensional direction and performing the above-described measurement, the pupil luminance distribution regarding a plurality of points on the irradiated surface (second surface) is measured. The measurement of the pupil luminance distribution will be further described later.

  Returning to FIG. 1, an alignment system AS for detecting an alignment mark and a reference mark formed on the wafer W is provided on the side surface of the lens barrel 40 of the projection unit PU. As the alignment system AS, for example, an image processing method in which a mark is illuminated and detected by broadband light such as a halogen lamp and the position of the mark is measured by performing image processing on the detected mark image (image). An FIA (Field Image Alignment) system, which is a kind of imaging type alignment sensor, is used.

  Although not shown in the exposure apparatus 100, TTR (Through The Reticle) alignment using light having an exposure wavelength disclosed in, for example, US Pat. No. 5,646,413 is provided above the reticle stage RST. A pair of reticle alignment systems comprising the system is provided. A detection signal of the reticle alignment system is supplied to main controller 20.

  The control system is mainly configured by a main controller 20 in FIG. The main controller 20 is composed of a so-called workstation (or microcomputer) composed of a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc. Control all over. The main controller 20 includes, for example, a storage device 42 including a hard disk, an input device 45 including a pointing device such as a keyboard and a mouse, a display device 44 such as a CRT display (or liquid crystal display), and a CD (compact disc). , DVD (digital versatile disc), MO (magneto-optical disc) or FD (flexible disc) drive device 46 is connected externally.

  In the storage device 42, information on the light source shape (pupil luminance distribution) in which the projection state of the projection image projected onto the wafer W by the projection optical system PL is optimum (for example, aberration or line width is within an allowable range), Control information of the corresponding illumination system IOP, in particular, the mirror element SE of the spatial light modulator 3S, information on the aberration of the projection optical system PL, and the like are stored.

  The drive unit 46 includes an SMO (Source and Mask Optimization) program for optimally designing a light source shape and a reticle pattern, a light source condition optimization program for further optimizing a solution of the light source shape by SMO (SMO solution), and luminance as described later. An information recording medium (a CD-ROM for convenience in the following description) on which a conversion program for converting a measurement result of the distribution measuring device 80 into a Zernike coefficient, which will be described later, is set. Note that these programs may be installed in the storage device 42. Main controller 20 reads these programs onto the memory as appropriate.

  In the exposure apparatus 100, as in a normal scanner, after performing preparatory work such as wafer exchange, reticle exchange, reticle alignment, baseline measurement of the alignment system AS, and wafer alignment (such as EGA), exposure in a step-and-scan manner is performed. Operation is performed. Detailed description is omitted.

  Next, the control principle of the spatial light modulation unit 3 (spatial light modulator 3S) in the exposure apparatus 100 of the present embodiment will be described.

  In the exposure apparatus 100, the spatial light modulator 3S (tilt of the mirror element SE) is based on design data of the light source shape (pupil luminance distribution) and / or modulation amount data (hereinafter referred to as modulation data). By being controlled by the control unit (in this case, the main controller 20), the illumination light intensity distribution (pupil luminance distribution) on the illumination pupil plane, that is, the light source shape is reproduced.

The light source shape (pupil luminance distribution) actually formed by the spatial light modulator 3S is expressed using coordinates in the pupil plane, for example, a function Ψ (ξ, η) of orthogonal coordinates ξ, η. This pupil luminance distribution is considered to be generally different from the originally desired pupil luminance distribution Ψ _DESIGN (ξ, η) that was originally intended to be formed for the spatial light modulator 3S. As this factor, for example, various control errors of the spatial light modulator 3S itself, the transmittance distribution of the lens, or the aberration of the optical system can be considered. Therefore, feedback is actually applied to the spatial light modulator 3S so that Ψ (ξ, η) actually obtained is as close as possible to Ψ _DESIGN (ξ, η), or a few remain after multiple feedbacks. As a means of accurately grasping whether or not the amount of residual residue should be acceptable, modeling using causal relationship between Ψ _DESIGN (ξ, η) and Ψ (ξ, η) using some expression including multiple parameters This idea is effective.

The above causal relationship is generally
It can be expressed approximately using a modulation operation Q reflecting some realistic model and a plurality of modulation factors Z ₁ , Z ₂ ... Z _i . As an example of a model relating to the modulation operation and the modulation factor, here, a transmission modulation effect and a distortion modulation effect, which are typical as a distribution modulation operation by an optical system, will be described. First, in the case of the former transmittance modulation, the following expressions can be considered.

Here, T (ξ, η) means a net transmittance distribution function, and f _i (ξ, η) means a Fringe Zernike polynomial. The expansion coefficient Z _i of each order corresponds to 0 when there is no transmittance modulation, in which case the transmittance is exactly 1.

  In the case of distortion modulation, generally, the following can be expressed for pupil coordinate values before and after modulation.

For example, as shown in FIG. 5, this equation means that each position (ξ, η) (corresponding to each pixel in numerical calculation) in the pupil plane before modulation is represented by functions g _x and g _y . This is an operation to move slightly to the position (ξ ', η') determined based on this, and thereby the pupil luminance distribution modulation action based on the distortion action (distribution distortion) typified by, for example, a pincushion type or barrel type As a result. Note that such a distortion modulation action can be specifically defined by applying the Zernike polynomial expression described above. FIG. 12 means that. For example, when there is modulation of only a fourth-order distortion polynomial (Dist-4), it is embodied as the following expression (4).

Here, Z ′ ₄ corresponds to a fourth-order expansion coefficient of the distortion polynomial, and the magnitude of this fourth-order distortion action is determined by the magnitude of this numerical value. That is, DX and DY in FIG. 12 are unit vectors that mean which parameter is to be modulated with respect to each of the pupil plane coordinates ξ and η. Therefore, by using this distortion polynomial, a general modulation action can be expressed as a mixed effect of a plurality of orders of distortion modulation as in the following equation (5).

Here, D _i is a distortion polynomial (vector expression) of each order defined in FIG. 12, and Dξ and Dη are unit vectors for pupil plane coordinates ξ and η. If the distortion polynomial is defined in this way, the modulation effects of the respective orders correspond to operations orthogonal to each other, and thus have an advantage of being useful for change table management, index expression, and the like.

In this way, by modeling the modulation relationship between Ψ _DESIGN (ξ, η) and Ψ (ξ, η) in some specific form, for example, as described in detail later, each modulation parameter Z _It is possible to create a database of information for imaging performance change in the case of illumination luminance distribution modulated by the presence of only a small amount of _i . In addition, the objective is to effectively bring the imaging performance of the actually obtained illumination luminance distribution Ψ (ξ, η) closer to the imaging performance of the illumination luminance distribution Ψ _DESIGN (ξ, η) that is originally desired. Thus, it is possible to perform additional minute modulation of the illumination luminance distribution determined from the value of each modulation parameter Z _{i on} the spatial light modulator 3S.

Further, as another application of modeling regarding such modulation action, for example, by calculating the parameter group Z _i based on the equation (1) that matches the relationship between the images before and after the modulation by the least square method or the like, Even in the case of complex pupil luminance distribution that is different from conventional simple annular illumination or multipolar illumination that can be expressed only with such geometric parameters, it is a representative index value that determines the feature of the luminance distribution Z _i can be used, and the use of Z _i as a specification value is also conceivable.

  In addition to the above two types of models, for example, a blur effect caused by an optical system or a component such as flare light can be added as a model as necessary, so that more realistic illumination is possible. It is possible to express the modulation effect relating to the luminance distribution.

  Next, measurement of the light source shape (pupil luminance distribution) in the exposure apparatus 100 of the present embodiment will be described. The measurement of the light source shape (pupil luminance distribution) is performed in the above-described calculation parameter creation, light source shape (SMO solution) optimization (OPE matching) described later, and the like.

  Measurement of the light source shape (pupil luminance distribution) is started by an instruction from an operator or the like. After the instruction, main controller 20 calibrates the position of luminance distribution measuring instrument 80 prior to the start of measurement. Here, main controller 20 drives wafer stage WST via stage drive system 24 to position luminance distribution measuring instrument 80 mounted on wafer stage WST directly below alignment system AS. After positioning, main controller 20 detects an alignment mark (not shown) provided on luminance distribution measuring instrument 80 using alignment system AS. Main controller 20 uses the detection result of the alignment mark and the measurement result of interferometer system 18 at the time of detection to determine the accurate position of alignment mark on the stage coordinate system, that is, luminance distribution measuring instrument 80. Ask. Illumination light IL emitted from the illumination system IOP and reaching the image plane via the projection optical system PL passes through the opening on the cover glass 80a, passes through the condenser lens 80b, and is received by the light receiving element in the light receiving unit 80c. Received light.

  A light receiving element (such as a two-dimensional CCD) in the light receiving unit 80c detects the light intensity in the cross section of the illumination light IL that has passed through the opening on the cover glass 80a (measures the light intensity distribution). This light intensity distribution corresponds to the pupil luminance distribution Ψ (ξ, η) for a part of the illumination light IL. Here, FIG. 4 shows the relationship between the image plane (image plane coordinate system) and the pupil plane (pupil plane coordinate system) of the projection optical system PL.

  The main controller 20 transfers the measurement result of the light source shape (pupil luminance distribution) Ψ (ξ, η) to a host computer or the like. Strictly speaking, since the light source shape (pupil luminance distribution) is measured at discrete points on the pupil plane coordinate system, the measurement result Ψ (ξ, η) is given as discrete data.

  In the exposure apparatus 100 of the present embodiment, since the illumination light IL is detected via the projection optical system PL, the measurement result of the pupil luminance distribution Ψ (ξ, η) is influenced by the modulation by the projection optical system PL (aberration). Including the influence of optical characteristics such as). In the optimization of the light source shape, which will be described later, it is desirable that the influence of such modulation is removed from the measurement result of the pupil luminance distribution Ψ (ξ, η).

When the Mueller matrix of the projection optical system PL is M, and the Stokes parameters on the wafer W and the reticle R are S _w and S _r , respectively, these relations are as follows.
S _w = MS _r (6)
Therefore, by calculating the inverse matrix M ⁻¹ of M and multiplying both sides of the above equation (6), S _w can be converted to S _r as in the following equation.
S _r = M ⁻¹ S _w (7)

  Next, the optimum design of the light source shape (pupil luminance distribution) and mask pattern by SMO (Source and Mask Optimization) will be briefly described.

  In the exposure apparatus 100 of this embodiment, the pattern surface of the mask (reticle) can be illuminated with a desired (arbitrary) illuminance distribution by using the spatial light modulation unit 3 (spatial light modulator 3S). As a result, it is possible to further improve the contrast of the projected image, the depth of focus, etc., exceeding the adjustment limit of the illumination conditions by conventional illumination such as annular illumination and multipole illumination.

  As described above, the spatial light modulator 3S includes a plurality (J) of mirror elements SE, and each mirror element SE is independently tilted about two orthogonal axes so that the reflection direction of the light beam LB is within the beam cross section. By partially modulating, a desired light source shape (pupil luminance distribution) is formed.

  Here, the spatial light modulator 3S has at least a number (2J) of degrees of freedom equal to the product of the number of mirror elements SE and the number in the tilt direction. The shape of the illumination light source (light source shape) is set using the spatial light modulator 3S having such a large number of degrees of freedom, and the pattern formed on the mask is accurately transferred onto the wafer (that is, the projected image of the pattern). In recent years, an SMO that optimally designs both a light source shape (pupil luminance distribution) and a mask pattern has been used in process development.

  FIG. 6 shows an overview of the SMO procedure. In starting SMO, the target of the pattern to be transferred onto the wafer (target pattern), the initial design of the light source shape and mask pattern (initial conditions), and various conditions related to the optimal design (optimization evaluation method, performance of the exposure apparatus) Specify the constraints derived from As an example, the light source shape and the mask pattern are optimally designed so that the focus range (depth of focus) in which the contrast of the projected image within the allowable range can be obtained is maximized with respect to the target pattern shown in FIG. . In the target pattern of FIG. 7A, the bright pattern and the dark pattern are represented by using white circles and black circles, respectively. The boundary between both patterns is a so-called log slope.

  First, a mask pattern that obtains a projected image of a target pattern with the maximum depth of focus is obtained for the light source shape designated as the initial condition. In this embodiment, a phase shift mask that can continuously modulate the light transmittance from zero to 1 and the phase of transmitted light from zero to π is employed. Therefore, a transmittance distribution and a phase shift distribution are designed as mask patterns. The mask pattern specified as the initial condition is repeatedly optimized by applying, for example, a trial and error method which is a kind of analysis method. After the optimization, a light source shape that obtains a projected image of the target pattern with the maximum depth of focus is obtained for the obtained mask pattern. The light source shape designated as the initial condition is repeatedly optimized by applying, for example, a trial and error method.

  Next, the same optimization is performed on the light source shape and the mask pattern obtained by the optimization in the first cycle. The same optimization is further repeated, and each time it is repeated, the depth of focus (maximum depth of focus) at which the contrast of the projected image within the allowable range is obtained is obtained. When the obtained maximum depth of focus converges within the specified convergence rate range, the iteration is terminated.

  Finally, the SMO solution of the light source shape and mask pattern, and the performance of the SMO solution are reported. For the target pattern in FIG. 7A, the light source shape (pupil luminance distribution) shown in FIG. 7B and the transmittance distribution and phase of the mask pattern shown in FIGS. 7C and 7D, respectively. A shift distribution is obtained. Also, with respect to the optimally designed light source shape (pupil luminance distribution) and mask pattern, as shown in FIGS. 7E to 7G, the contrast within the allowable range within the focal depth of 100 nm. It can be seen that a projected image of the target pattern can be obtained.

  In the present embodiment, the above-described SMO is performed by a host computer that performs overall management of a device manufacturing system including the exposure apparatus 100 and the like. A mask is manufactured based on the optimally designed mask pattern. Here, a plurality of masks used to manufacture at least one device are manufactured. The design data of the optimally designed light source shape corresponding to the manufactured mask pattern is stored (stored) in the storage device 42 connected to the main controller 20 of the exposure apparatus 100. The main controller 20 reads design data of the light source shape corresponding to the mask pattern from the storage device 42 during the exposure process or the like, and based on the read design data of the light source shape, the spatial light modulator 3S as described above. The light source shape (pupil luminance distribution) is reproduced by controlling (the inclination of the mirror element SE).

  However, as described above, the light source shape (pupil luminance distribution) reproduced by the spatial light modulation unit 3 (spatial light modulator 3S) deviates from the light source shape (SMO solution) optimally designed by SMO due to various errors. Due to this deviation, the imaging performance, particularly OPE, is different from the target value (OPE error occurs).

  FIG. 8A shows an SMO solution of the light source shape (pupil luminance distribution). FIG. 8B shows the line width of the test pattern image projected on the wafer in the exposure apparatus 100 (result of the imaging simulation) for the SMO solution. Here, as the test pattern, a line and space pattern including a plurality of (eight) line patterns having a line width of 45 nm and a pitch of 110 to 500 nm is used. As is clear from FIG. 8B, the line width slightly deviates from the design (45 nm), but the degree of deviation is small and the dependence on the pitch and defocus is not large.

  FIG. 8C shows a light source shape (pupil luminance distribution) reproduced by a spatial light modulation unit similar to the spatial light modulation unit 3 (spatial light modulator 3S) based on the SMO solution of FIG. It is shown. The light source shape (pupil luminance distribution) is measured using a measuring device similar to the luminance distribution measuring device 80 as described above. As apparent from the comparison with the SMO solution, it can be seen that the contour is reproduced almost accurately, but the fine shape is not reproduced, the contour is smooth, and the edge slope is gentle.

  FIG. 8D shows the detection result of the line width of the test pattern transferred onto the wafer using the exposure apparatus similar to the exposure apparatus 100 with respect to the reproduced light source shape (pupil luminance distribution). It is shown. As apparent from the comparison with FIG. 8B, the detection result of the line width largely deviates from the design (45 nm) and also changes with respect to the pitch. Furthermore, it can be seen that the degree of change becomes more prominent as defocus increases.

  As can be seen from the above description, when manufacturing a device with a device rule of 32 nm or less in the future, it is necessary to further optimize the light source shape (SMO solution) designed by the SMO, particularly considering the OPE error.

Conventionally, as one means of OPE matching, fine adjustment has been performed on the illumination luminance distribution. In that case, if it is a simple circular illumination, fine adjustment that changes its radius is made by making full use of a movable mechanism in the illumination system, and if it is annular illumination, the outer diameter and inner diameter are finely adjusted. Things have been done. On the other hand, in recent years, as described above, a very complicated illumination luminance distribution is often required, and the presence of the spatial light modulator 3S is positioned as a specific means for realizing such an illumination luminance distribution. In order to achieve a desired imaging performance as a result of performing some fine adjustment on such a complicated illumination luminance distribution, as described above, the illumination luminance distribution that was originally desired was actually formed. It may be desirable to manage and control several parameters (corresponding to Z ₁ , Z ₂ ... Z _i in equation (1)) regarding the modulation contents between illumination luminance distributions. This is because such a modulation parameter is a physical quantity that does not depend on the original illumination luminance distribution at all. Therefore, even if the distribution is complex, the feature of the actually measured illumination luminance distribution is expressed with the same parameters. This is because it can.

  Therefore, in the following, without being limited only to OPE matching, for example, at least one of the physical indices related to the resulting imaging performance such as process window information is driven to the originally desired performance. Explain how to go. That is, one of the methods includes OPE matching for a typical imaging performance index called OPE.

  A physical quantity representing the resulting imaging performance is denoted here as U. Assuming that the mask information actually used is always the same, this physical quantity U is linked in the following relationship.

Here, P means an arithmetic operation for calculating U, which is a physical quantity for image formation performance evaluation represented by OPE, when a specific illumination luminance distribution is given. That is, for example, it corresponds to wave optical imaging calculation for a projection optical system. At that time, the evaluation index value obtained in the case of the originally desired illumination luminance distribution Ψ _DESIGN (ξ, η) is defined as follows.

Here, the physical quantity that we really should pay attention to is the relative change from the ideal state regarding the imaging performance in the case of the actually obtained illumination luminance distribution. If the relative change is Δ, it can be defined as follows.

Here, Δ can be interpreted as a function depending on the following physical quantity, taking into account the equation (1).

That is, depending on a plurality of parameters Z ₁ , Z _2, ... Z _i that determine minute changes from the originally desired illumination luminance distribution, the explanation can be made by a causal relationship that a predetermined imaging performance deviates from the originally desired state. However, the relationship between the parameter and Δ is generally a complex non-linear relationship. However, rough feedback has already been completed by the spatial light modulator 3S, and the stage where the desired imaging performance is obtained by minute modulation that also takes into consideration the imaging performance viewpoint has been reached. If the assumption is made, it becomes effective to treat the change from 0 of 0 when the parameter Z _i has a finite value by a minute amount as a linear change.

As described above, when the objective is to obtain the desired imaging performance by minute modulation, it is necessary to prepare in advance a plurality of parameters Z ₁ , Z ₂ ... That determine minute changes from the desired illumination luminance distribution. It becomes a series of change table information concerning how much Δ changes by each small modulation of Z _i . That is, the following changes in Δ when Z ₁ , Z ₂ ... Z _i are close to 0, that is, information on slope (partial differentiation) is required.

Specifically, this information is obtained by performing an imaging calculation on an illumination luminance distribution that is minutely modulated by a minute amount Z _i , and calculating a change Δ from an ideal value regarding the imaging physical index obtained thereby, This value can be calculated by dividing by the Z _i that was originally used to modulate. Then, the same operation is calculated for a series of modulation parameters.

Hereinafter, a micro-modulation feedback method for an illumination luminance distribution represented by OPE matching will be described using the above-described change table information. First, with respect to an actual illumination luminance distribution Ψ (ξ, η) that requires such feedback, its imaging performance is calculated based on the equation (8). A deviation amount Δ with respect to the imaging performance index value from the ideal luminance distribution obtained thereby is defined as Δ _REAL . Next, least square fitting is performed so that Δ _REAL can be restored by linear combination based on the change table information of Expression (12).

Here, c ₁ , c ₂ ,..., C _i mean coefficients as a result of fitting. FIG. 9 shows an example of fitting based on the equation (13). In the case of OPE evaluation, Δ is a function that targets the pitch of the pattern, and therefore, in practice, such a function distribution is subjected to fitting. In the example of FIG. 9, based on the change table information according to some parameters changing the illumination brightness distribution, in order to fit the OPE curve of solid line delta _REAL is, by combining what modulation in any weight The fitting means that the same effect can be expected. Then, based on the coefficients c ₁ , c ₂ ,..., C _i obtained by this fitting, the illumination luminance distribution Ψ (ξ, η) obtained at the present stage is subjected to the inverse modulation, that is, the expression (1) ), The following modulation is additionally performed.

Thereby, the imaging performance index value U by the illumination luminance distribution Ψ _OPTIMIZED (ξ, η) subjected to predetermined additional modulation is the evaluation index value obtained in the case of the originally desired illumination luminance distribution Ψ _DESIGN (ξ, η). It can be expected to be close to U ₀ . Even if the feedback is in a region where linearity is not established, the above-described fitting operation can be performed several times sequentially to achieve a desired optimization.

  FIG. 10 is a flowchart showing a schematic procedure of OPE matching of the SMO solution. The OPE matching of the SMO solution starts when instructed by an operator or the like via the input device 45.

  Prior to the OPE matching of the SMO solution, it is assumed that the light source shape and the mask pattern are optimally designed by the above-described SMO, and the design data is stored (stored) in the storage device 42.

  In the first step 202, the optimization condition of the light source shape, for example, the SMO solution of the light source shape (illumination luminance distribution) and the mask pattern, the model expressing the light source shape (the modulation operation Q in the equation (1)), OPE Test pattern (type, projection position, etc.) for evaluating OPE error), index (physical quantity) to be evaluated as OPE error and its allowable limit, index for evaluating light source shape, its allowable limit, and reference light source shape ( Reference shape) << Ψ >> and the like are set. Here, main controller 20 reads the SMO solution of the light source shape and the mask pattern from storage device 42. Other conditions are set by an operator or the like via the input device 45. As an example, a plurality of (K) types of line and space patterns (k = 1 to K) which are different from each other in the range of the same line width of 45 nm and a pitch of 110 to 500 nm as a test pattern, and an imaging line as an evaluation index of OPE error A width error (line width error), an RMS (Root Mean Square) error from the reference shape, and the like are set as an evaluation index of the light source shape.

Further, as a model expressing the modulation operation Q in the equation (1), the Zernike polynomial shown in FIG. 11 or the distortion function shown in FIG. 12 is set. Further, the SMO solution Ψ _DESIGN (ξ, η) is selected as the reference shape << Ψ >>.

The main controller 20 controls the spatial light modulator 3S based on the SMO solution Ψ _DESIGN (ξ, η) of the light source shape. As a result, the light source shape Ψ (ξ, η) is obtained. In general, the obtained light source shape Ψ (ξ, η) deviates from Ψ _DESIGN (ξ, η). It is assumed that the projection optical system PL (and the light transmission optical system 10) is in the reference state through the OPE matching.

In the next step 204, an OPE change table, which is a kind of imaging performance change table, is created. Here, the OPE change table is partial differential information defined by Expression (8). Main controller 20 calculates partial differential information for line width error Δ _{CD, k} for the _k -th test pattern (= 1 to K) set as an index for evaluating OPE error Δ in step 202. The obtained numerical data of partial differential information is held in a memory (not shown) in a table format.

In the next step 206, the light source shape is set by controlling the spatial light modulator 3S based on the modulation operation Q (modulation parameters Z _{1 to} Z _i ). Here, since the modulation parameters Z _{1 to} Z _i are not given (Z _{1 to} Z _i = 0), the modulation is not performed. Therefore, the light source shape Ψ (ξ, η) initialized in step 202 is maintained.

  In the next step 208, the light source shape Ψ reproduced on the exposure apparatus 100 in step 206 is measured using the luminance distribution measuring device 80. The details of the measurement method are as described above. The measurement result of the light source shape Ψ is denoted as <Ψ>.

In the next step 210, the measurement result <Ψ> of the light source shape obtained in step 208 is evaluated. Main controller 20 obtains RMS error ε between measurement result <Ψ> and reference shape << Ψ >>. Main controller 20 determines whether or not the calculated RMS error ε is within the allowable limit ε ₀ set in step 202, so that the deviation of the light source shape from the target is within the allowable range. That is, the degree of coincidence of the set shape of the illumination light source with respect to the target light source shape is evaluated. If the determination in step 210 is negative, the process proceeds to step 212. Here, main controller 20 may evaluate the degree of coincidence as a numerical value based on the obtained RMS error ε instead of the process of step 210.

Since the light source shape SMO solution Ψ _DESIGN (ξ, η) is given as the reference shape << Ψ >> as described above, the light source shape obtained by the OPE matching greatly deviates from the SMO solution, and further the OPE. It is avoided that the matching optimization flow diverges.

In step 212, main controller 20 creates candidates for modulation data ΔΨ (modulation parameters Z _{1 to} Z _i ) that give RMS error ε of allowable limit ε ₀ or less with respect to light source shape ψ. As an example, a candidate of modulation data ΔΨ is given as ΔΨ = w (<< Ψ >> − Ψ) using a weight 0 <w <1. The weight w is set in step 202. When the modulation data ΔΨ is given, the main controller 20 develops using the set model, that is, using the product of the Zernike polynomial and the reference shape, or the product of the distortion function and the reference shape. Modulation parameters Z _{1 to} Z _i are obtained from the expansion coefficient, and the process returns to step 206.

  On the other hand, if the determination in step 210 is affirmed, the process proceeds to step 214.

In step 214, the imaging performance, that is, the line width (line width error) set in step 202 is predicted using the measurement result <Ψ> of the light source shape measured in step 208. Here, the line width (delta _CD, denoted as _k) is predicted for k kinds th test pattern set in step 202 (k = 1~K).

Note that the line width Δ _{CD, k} may be predicted for several types of focus. Further, the line width Δ _{CD, k} may be predicted for several exposure doses (exactly, exposure time).

By the above prediction, the same line width prediction results as those in FIGS. 8B and 8D can be obtained. From these results, a deviation (line width error) from the true line width (45 nm) is obtained. Note that a deviation (line width error) predicted for the kth test pattern is represented as <Δ _{CD, k} >.

In the next step 216, it is determined whether or not the line width error <Δ _{CD, k} > predicted in step 214 is within an allowable range (imaging performance is evaluated). Specifically, main controller 20 determines the average (weighted average) <Δ _{CD, AVG} > or the line width error for all test patterns (k = 1 to K) of line width error <Δ _{CD, k} >. It is determined whether the maximum value <Δ _{CD, MAX} > is within the allowable limit set in step 202. If the determination in step 216 is negative, further optimization of the light source shape is required, and the process proceeds to step 218.

In step 218, modulation parameters Z _{1 to} Z _i are determined from the line width error <Δ _{CD, k} > (k = ₁ to K) predicted above. Main controller 20 assigns line width error <Δ _{CD, k} > (k = 1 to K) to the left side of equation (13) and change table information to each term on the right side, and simultaneously applies K linear equations. A set of coefficients c _{1 to} c _{i to be} satisfied is determined using a least square method or the like. These coefficients c _{1 to} c _i give the modulation parameters Z _{1 to} Z _i . When the modulation parameter is obtained, the process returns to step 206.

On the other hand, if the determination in step 216 is affirmative, that is, if it is determined that the predicted line width error <Δ _{CD, k} > is within the allowable range, the process proceeds to the next step 220.

  In the next step 220, test exposure is performed using a test reticle. Here, as the test reticle, a reticle on which the k-th test pattern (k = 1 to K) set in step 202 is formed is used. Main controller 20 performs the above-described exposure operation to expose the wafer. After completion of exposure, main controller 20 conveys the exposed wafer to exposure apparatus 100, for example, a coater / developer (C / D) (not shown) connected in-line, and develops it. Main controller 20 loads the developed wafer again onto wafer stage WST, detects a resist image of the test pattern formed on the wafer using alignment system AS, and obtains the line width (line width error). . However, the present invention is not limited to this, and the line width (line width error) of the resist image may be measured by SEM or the like after the development of the wafer.

  In the test exposure, the exposure may be performed for several kinds of focus. Further, exposure may be performed with respect to several exposure doses (exactly, exposure time).

By the above test exposure, the detection result of the line width similar to that in FIGS. 8B and 8D is obtained. Since the OPE is reflected in the detection result of the line width in the test exposure, the deviation (line width error) from the true line width (45 nm) becomes more remarkable. The deviation (line width error) obtained for the kth test pattern is denoted as <Δ _{CD, k} >.

In the next step 222, it is determined whether or not the line width error <Δ _{CD, k} > obtained in step 220 is within an allowable range (imaging performance is evaluated). Specifically, main controller 20 determines the average (weighted average) <Δ _{CD, AVG} > or the maximum line width error for all test patterns (k = 1 to K) of line width error <Δ _{CD, k} >. It is determined whether <Δ _{CD, MAX} > is greater than the allowable limit set in step 202. If larger, it is determined that further optimization of the light source shape is required, and the routine proceeds to step 218.

In step 218, modulation parameters Z _{1 to} Z _i are obtained from the line width error <Δ _{CD, k} > (k = ₁ to K) obtained above. Main controller 20 assigns line width error <Δ _{CD, k} > (k = 1 to K) to the left side of equation (13) and change table information to each term on the right side, and simultaneously satisfies the K linear equation. A set of coefficients c _{1 to} c _i is determined using a least square method or the like. These coefficients c _{1 to} c _i give the modulation parameters Z _{1 to} Z _i . When the modulation parameter is obtained, the process returns to step 206.

Returning to step 206, the light source shape is modulated using the modulation data ΔΨ obtained in step 212 or 218, that is, the modulation parameter ΔZ _i (i = 1 to I). Thereby, the optimized light source shape (pupil luminance distribution) is reproduced.

  Thereafter, steps 206 to 220 are repeated until the determination in step 222 is affirmed.

If the determination in step 222 is affirmed, an optimal light source shape Ψ _OPTIMIZED (ξ, η) that minimizes the line width error <Δ _{CD, k} > (k = 1 to K) is obtained, and OPE matching ends. Here, main controller 20 reports the optimal light source shape Ψ _OPTIMIZED (ξ, η) and the corresponding line width error <Δ _{CD, k} > (k = 1 to K) on a display device (not shown), The obtained optimal light source shape Ψ _OPTIMIZED (ξ, η) is stored (stored) in the storage device 42.

  When exposing the wafer, main controller 20 reads design data of optimum light source shape Ψ corresponding to the mask pattern from a storage device (not shown), and based on the design data, spatial light modulator 3S (mirror element) The light source shape (pupil luminance distribution) is reproduced by controlling the SE inclination. Then, a step-and-scan exposure operation is executed in the same manner as a normal scanner.

  Although not particularly described in the above description, in the OPE matching of the SMO solution of the present embodiment, the test pattern projection positions for evaluating the OPE (OPE error) are at different positions on the imaging plane. It has been established. This makes it possible to accurately optimize the light source shape, that is, the luminance distribution in almost the entire pupil plane, over almost the entire imaging plane.

  In step 220, test exposure was performed using the kth type test pattern (= 1 to K), and the pattern transferred to the wafer was detected to evaluate the imaging performance (line width error). Alternatively or in combination, a photodetector (luminance distribution measuring device 80 or the like) provided on wafer stage WST, or aerial image measurement disclosed in, for example, US Patent Application Publication No. 2002/0041377. The imaging performance (line width error) can also be evaluated by detecting the projected image of the k-th type test pattern using a detector. Here, the imaging performance (line width error) may be evaluated in consideration of resist characteristics and the like.

As described above in detail, in the present embodiment, the light source shape Ψ or the light source shape Ψ obtained as a result of SMO (SMO solution) which is an optimization calculation method for optimizing the mask pattern and the illumination light source is obtained. The light source shape modulated by the modulation data ΔΨ of the light source shape is used to control the spatial light modulator 3S as a light source shape target to set the shape of the illumination light source (light source shape), and from the illumination light source having the set light source shape The illumination light is irradiated onto the wafer surface via the projection optical system PL, the intensity distribution (light source shape) of the illumination light on the pupil plane of the illumination optical system is measured, and the measurement result <Ψ> is targeted. Based on whether or not the RMS error ε with respect to the reference shape << ψ >> is within the allowable limit ε ₀ , ie, the intensity distribution of the illumination light corresponding to the light source shape on the pupil plane of the illumination optical system, From that light source shape target Is (matching degree of the shape of the illumination light source that has been set for the light source shapes are targeted) is evaluated. This makes it possible to accurately evaluate the deviation of the light source shape from the target.

  In the present embodiment, the shape of the illumination light source matches the target light source shape based on the degree of matching of the set shape of the illumination light source with respect to the target light source shape evaluated as described above. Adjusted (set). This makes it possible to set an optimal light source shape for a pattern obtained as a result (solution) of SMO, which is an example of optimization calculation for optimizing the pattern and the illumination light source. In addition, since the reticle has a pattern obtained as a solution of SMO, the reticle pattern can be formed on the wafer with high resolution by using illumination light generated by an illumination light source having a set light source shape. It becomes possible to transfer with high accuracy.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described. Here, the second embodiment is different from the first embodiment described above only in part of the OPE matching procedure of the SMO solution. Below, it demonstrates centering on such a difference.

  FIG. 13 is a flowchart showing a schematic procedure of OPE matching of the SMO solution according to the second embodiment.

  In the first step 302, a light source shape optimization condition and the like are set in the same manner as in step 202 of the first embodiment described above. In this step 302, as an evaluation index of the light source shape, a line width error which is a kind of index value of the OPE error and its allowable limit are set instead of the RMS (Root Mean Square) error from the reference shape described above. Except for the points, the same conditions as in step 202 are set. Not only the line width error but also an appropriate OPE error index value such as distortion can be set as an evaluation index of the light source shape.

  In steps 304, 306, and 308, processing similar to that in steps 204, 206, and 208 described above is performed.

In the next step 314, the imaging performance, that is, the line width Δ _{CD, k} (line width error) set in step 302 is predicted using the measurement result <Ψ> of the light source shape measured in step 308. The Here, the line width is predicted for the k-th test pattern (k = 1 to K) set in step 302.

Note that the line width Δ _{CD, k} may be predicted for several types of focus. Further, the line width Δ _{CD, k} may be predicted for several exposure doses (exactly, exposure time).

In the next step 316, whether or not the (predicted) line width ΔCD _{, k} obtained by calculation in step 314 is within the allowable limit set in step 302, that is _, OPE using ΔCD _{, k} as an index value. Determine whether the error is within acceptable limits. Thus, whether or not the deviation of the light source shape from the target is within an allowable range, that is, the degree of coincidence of the set shape of the illumination light source with respect to the target light source shape is evaluated. If the determination in step 316 is negative, the process proceeds to step 312.

In step 312, main controller 20 creates candidates for modulation data ΔΨ (modulation parameters Z _{1 to} Z _i ) that give an OPE error below the allowable limit for light source shape Ψ. As an example, a candidate of modulation data ΔΨ is given as ΔΨ = w (<< Ψ >> − Ψ) using a weight 0 <w <1. The weight w is set in step 302. When the modulation data ΔΨ is given, the main controller 20 develops using the set model, that is, using the product of the Zernike polynomial and the reference shape, or the product of the distortion function and the reference shape. Modulation parameters Z _{1 to} Z _i are obtained from the expansion coefficient, and the process returns to step 306.

  On the other hand, if the determination in step 316 is affirmative, that is, if the determined OPE error is within the allowable limit set in step 302, the process proceeds to step 320.

  In steps 320, 322, and 318, the processing or determination of steps 220, 222, and 218 described above is performed, respectively.

  As described above, in the second embodiment, the light source shape Ψ or the light source shape Ψ obtained as the result of SMO (SMO solution) as an optimization calculation method for optimizing the pattern and the illumination light source is used as the light source. The light source shape modulated by the shape modulation data ΔΨ is generated by an illumination light source having the set shape by controlling the spatial light modulator 3S as a light source shape target to set the shape of the illumination light source (light source shape). The illumination light is irradiated onto the wafer surface via the projection optical system PL, the intensity distribution (light source shape) of the illumination light on the pupil plane of the illumination optical system is measured, and the index value corresponding to the measured intensity distribution And the degree of coincidence of the set shape of the illumination light source with respect to the target shape is evaluated based on the difference between the target value and the index value corresponding to the intensity distribution of the illumination light corresponding to the target shape. Here, as an index value of the intensity distribution of the illumination light on the pupil plane of the illumination optical system, the pattern formed on the wafer when the illumination light having the intensity distribution is irradiated onto the pattern obtained as the SMO solution is used. A predetermined imaging performance of an image, that is, an OPE error (a line width that is an index value) is used. This makes it possible to accurately evaluate the deviation of the light source shape from the target.

  In addition, according to the second embodiment, as in the first embodiment, it is optimal for the pattern obtained as a result (solution) of SMO, which is an example of optimization calculation for optimizing the pattern and the illumination light source. A simple light source shape can be set. In addition, since the reticle has a pattern obtained as a solution of SMO, the reticle pattern can be formed on the wafer with high resolution by using illumination light generated by an illumination light source having a set light source shape. It becomes possible to transfer with high accuracy.

<< Third Embodiment >>
Next, a third embodiment of the present invention will be described. Here, the third embodiment is different from the first embodiment described above only in part of the OPE matching procedure of the SMO solution. Below, it demonstrates centering on such a difference.

  FIG. 14 is a flowchart showing a schematic procedure of OPE matching of the SMO solution according to the third embodiment.

In the first step 402, a light source shape optimization condition and the like are set in the same manner as in step 202 of the first embodiment described above. In this step 402, as an evaluation index of the light source shape, a process window of OPE error is set instead of the RMS (Root Mean Square) error from the reference shape described above. Here, the process window means that the illumination light having the light source shape, that is, the intensity distribution, is changed in focus (position of the surface of the wafer W in the optical axis AX direction) with respect to each of the plurality of patterns, and the wafer W. When the dose of illumination light (exposure dose) applied to is changed and irradiated, a predetermined imaging performance of an image of the pattern formed on the wafer, for example, an OPE error is applied to all of the plurality of patterns. It means an area defined by a focus range and an exposure dose range that are commonly within a predetermined range. In this embodiment, since the OPE error is represented by the line width that is the index value, the process window of the OPE error is a process window of the line width error. A tolerance limit for line width error to define the process window is set. In addition, a threshold value of an evaluation standard (ratio S / S ₀ described later) for evaluating the process window is set. Other than these conditions, conditions similar to those in step 202 are set. Instead of the line width error, an appropriate index value of OPE error such as distortion may be used.

  In steps 404, 406, and 408, processing similar to that in steps 204, 206, and 208 described above is performed.

In the next step 414, a process window of line width error (OPE error) is predicted using the target light source shape set in step 406 and the light source shape measured in step 408. As an example, the target light source shape shown in FIG. 15A and the measurement result of the light source shape shown in FIG. 15C are used. Main controller 20 performs the k-th test in which the line widths (represented as χ _{CD, k} and <χ _{CD, k} >, respectively) are set in step 402 in the same manner as in step 314 in the second embodiment. For the pattern (k = 1 to K), calculation is performed at several focus and exposure doses.

FIG. 15B and FIG. 15D show process windows (shaded portions in the figure) having line widths χ _{CD, k} and <χ _{CD, k} >, respectively. The process window is determined as follows. First, for each of the K types of test patterns, the calculation results of the line widths χ _{CD, k} and <χ _{CD, k} > are plotted against the focus (defocus based on the best focus position) and the exposure dose. The As a result, contour maps as shown in FIGS. 15B and 15D are created. Next, for each of the K types of test patterns, a two-dimensional region of defocus and exposure dose that gives a line width within the allowable limit set in step 402 is extracted. Finally, among these two-dimensional areas, a two-dimensional area common to all (K types) test patterns is obtained as a process window.

In the next step 416, the light source shape is evaluated by using the (predicted) process window obtained in the calculation in step 414. Specifically, the main controller 20, for example, processes the area S of the process window having the line width χ _{CD, k} of the common area S of the process windows of the line width χ _{CD, k} , <χ _{CD, k} >. the ratio S / S ₀ for _0, determines whether a set threshold or more in step 402. Thus, the deviation between the target light source shape and the light source shape reproduced on the exposure apparatus 100 is evaluated. If the ratio S / S ₀ is smaller than the threshold value, the target light source shape and the light source shape reproduced on the exposure apparatus 100 are largely shifted, so the determination in step 416 is negative, and step 412 is performed. Migrate to

In step 412, main controller 20 creates candidates for modulation data ΔΨ (modulation parameters Z _{1 to} Z _i ) that give an OPE error below the allowable limit for light source shape Ψ. As an example, a candidate of modulation data ΔΨ is given as ΔΨ = w (<< Ψ >> − Ψ) using a weight 0 <w <1. The weight w is set in step 402. When the modulation data ΔΨ is given, the main controller 20 develops using the set model, that is, using the product of the Zernike polynomial and the reference shape, or the product of the distortion function and the reference shape. Modulation parameters Z _{1 to} Z _i are obtained from the expansion coefficient, and the process returns to step 406.

On the other hand, if the determination in step 410 is affirmative, that is, if the ratio S / S ₀ is greater than or equal to the threshold set in step 402, the process proceeds to step 420.

  In steps 420, 422, and 418, the processes or determinations of steps 220, 222, and 218 described above are performed, respectively.

As described above, in the third embodiment, the light source shape Ψ or the light source shape Ψ obtained as a result of SMO (SMO solution) as an optimization calculation method for optimizing the pattern and the illumination light source is used as the light source. The light source shape modulated by the shape modulation data ΔΨ is generated by an illumination light source having the set shape by controlling the spatial light modulator 3S as a light source shape target to set the shape of the illumination light source (light source shape). The illumination light is irradiated onto the wafer surface via the projection optical system PL, the intensity distribution (light source shape) of the illumination light on the pupil plane of the illumination optical system is measured, and the index value corresponding to the measured intensity distribution And the set illumination light source for the target shape based on the ratio of the index value corresponding to the intensity distribution of the illumination light corresponding to the target shape (for example, the ratio S / S ₀ described above) Degree of matching The match is evaluated. Here, as an index value of the intensity distribution of the illumination light on the pupil plane of the illumination optical system, the pattern formed on the wafer when the illumination light having the intensity distribution is irradiated onto the pattern obtained as the SMO solution is used. The predetermined imaging performance of the image, that is, the area of the process window of the OPE error (the line width that is the index value) is used. This makes it possible to accurately evaluate the deviation of the light source shape from the target.

  In addition, according to the third embodiment, as in the first embodiment, the optimum pattern is obtained as a result (solution) of SMO, which is an example of optimization calculation for optimizing the pattern and the illumination light source. A simple light source shape can be set. In addition, since the reticle has a pattern obtained as a solution of SMO, the reticle pattern can be formed on the wafer with high resolution by using illumination light generated by an illumination light source having a set light source shape. It becomes possible to transfer with high accuracy.

  In the third embodiment, the process window of the predetermined imaging performance, that is, the OPE error (the line width that is the index value) is used as the index value of the intensity distribution of the illumination light on the pupil plane of the illumination optical system. Instead of the area, the projection depth is used to project the illumination light having the intensity distribution through the projection optical system, thereby giving a line width error within a predetermined range of the pattern image projected on the wafer. Also good. In this case, the setting for the target shape is set as an evaluation criterion based on the deviation of the index value corresponding to the measured intensity distribution with respect to the index value corresponding to the intensity distribution of illumination light corresponding to the target light source shape. The degree of coincidence of the shape of the illumination light source is evaluated.

Note that in the OPE matching of the second and third embodiments using both OPE error (referred to as DerutaOPE) and process window S / S _0, it is possible to evaluate the light source shape. In this case, for example, when the combined index F = aΔOPE + b / (S / S ₀ ) is defined and the combined index F exceeds a predetermined allowable limit F ₀ , the target light source shape and the light source reproduced on the exposure apparatus 100 It can be determined that the shape deviates greatly. Further, the RMS error of the light source shape employed in the first embodiment may be added to the coupling index F.

  In the OPE matching of the first to third embodiments, a Zernike polynomial or a distortion function is employed as a model expressing the modulation operation Q. As a result, the light source shape realized by the spatial light modulator 3S having a large number of degrees of freedom can be efficiently and accurately modulated with a small number of degrees of freedom corresponding to the number of terms of the Zernike polynomial or the distortion function. It becomes possible to obtain the light source shape.

  In each of the above embodiments, any polynomial can be used as long as it is suitable for describing the light source shape, without being limited to the Zernike polynomial or the distortion function. Further, although the Zernike polynomial and the distortion function are given in FIGS. 11 and 12, it is possible to use a polynomial excluding some of these terms.

In the OPE matching in the above embodiment, the modulation using the two models using the Zernike polynomial and the distortion function has been described as an example. However, the modulation that handles the blur effect can be performed by the same handling. The pupil luminance distribution Ψ (ξ, η) including the blur effect is a concatenation of the originally desired pupil luminance distribution Ψ _DESIGN (ξ, η) and the blur function (point spread function) B (ξ, η) representing the luminance distribution of the blur. As a convolution, Ψ (ξ, η) = (Ψ _DESIGN · B) * (ξ, η) is obtained. The function B is given by, for example, a Gaussian function having a width σ. The convolution is Fourier-transformed so that F (Ψ) = F (Ψ _DESIGN ) F (B) and the form similar to expression (2a), and F (B) meaning modulation is the same form as expression (2b). (Gauss function) is rewritten. Therefore, the width σ that minimizes the blur effect can be obtained and the light source shape can be modulated by the same handling as the OPE matching. It can also handle flare components. The modulation of the flare component is represented by the DC component within the power exponent on the right side of Equation (2b). Therefore, by the same handling as the OPE matching, the value of the DC component that minimizes the flare component can be obtained and the light source shape can be modulated.

  In each of the above embodiments, the case where the line width (line width error) of the pattern is used as the evaluation index of the OPE error has been described. However, the present invention is not limited to this, and imaging performance other than the line width error or a plurality of results are used. The OPE error can also be evaluated using the combination of image performance as an evaluation index.

  In each of the above embodiments, OPE matching, which is an example of matching of the imaging performance of the SMO solution, has been described. The OPE change table is used as the imaging performance change table, and the line width (line width error) of the pattern, which is one of the OPE error evaluation indexes, is used as the imaging performance evaluation index. The invention is not limited to this. That is, the matching of the imaging performance of the SMO solution is not limited to the OPE. For example, the imaging performance such as the distortion of the projected image is set as the object of matching of the imaging performance of the SMO solution, and the imaging performance change table corresponding thereto. And an evaluation index of the imaging performance may be used. In addition, a plurality of imaging performances may be defined as targets for SMO solution matching.

In each of the above embodiments, the OPE matching of the SMO solution has been described. However, not only SMO but also an optimization calculation that optimizes only the shape of the illumination light source may be performed using a predetermined pattern as a target pattern in advance. . Also in this case, the RMS error ε between the measurement result <Ψ> described in the first, second, and third embodiments and the target light source shape (that is, the reference shape << Ψ >>), the measurement result <Ψ > the ratio S / S ₀ an indication of the area of the process window of targeted light source shape of OPE error difference (line width which is the index value), the light source shape of OPE error (line width which is the index value) As a value, a method of evaluating the deviation of the light source shape from the target can be preferably applied.

  Further, in the exposure apparatus 100 of each of the above embodiments, the configuration in which the pupil luminance distribution is measured on the wafer surface using the luminance distribution measuring device 80 provided on the wafer stage WST is adopted. A configuration in which the pupil luminance distribution is provided on the reticle stage RST and the pupil luminance distribution is measured on the pattern surface of the reticle may be employed. In this case, since the measurement result of the pupil luminance distribution does not include the effect of the optical characteristics of the projection optical system PL, it is suitable for accurately measuring the pupil luminance distribution.

  In each of the above embodiments, the main controller 20 executes the OPE matching of the SMO solution according to the programs corresponding to the flowcharts shown in FIGS. 10, 13, and 14, but the host computer or device A dedicated computer connected to the manufacturing system may execute the program, and the main controller 20 may execute test exposure, light source shape measurement, and the like under these instructions.

  In the exposure apparatus 100 of the present embodiment, one spatial light modulation unit (spatial light modulator) is used, but a plurality of spatial light modulation units (spatial light modulators) can also be used. As an illumination optical system for an exposure apparatus using a plurality of spatial light modulation units, for example, an illumination optical system disclosed in US Patent Application Publication No. 2009/0109417 and US Patent Application Publication No. 2009/0128886 is used. Can be adopted.

  In addition, in the exposure apparatus 100 of the present embodiment, a spatial light modulator that independently controls the inclination of the mirror elements arranged two-dimensionally is employed. As such a spatial light modulator, for example, a European patent application is published. Spatial light modulators disclosed in US Pat. No. 779530, US Pat. No. 6,900,915 and US Pat. No. 7,095,546 can be employed.

  It is also possible to employ a spatial light modulator that independently controls the height of the mirror element as the spatial light modulator. As such a spatial light modulator, for example, the spatial light modulator disclosed in US Pat. No. 5,312,513 and US Pat. No. 6,885,493 can be employed. Furthermore, the above-described spatial light modulator can be modified in accordance with the disclosure of, for example, US Pat. No. 6,891,655 or US Patent Application Publication No. 2005/0095749.

  In the above embodiment, the case where the present invention is applied to the scanning stepper has been described. However, the present invention is not limited to this, and the present invention may be applied to a stationary exposure apparatus such as a stepper. The present invention can also be applied to a step-and-stitch reduction projection exposure apparatus that synthesizes a shot area and a shot area.

  In addition, as disclosed in, for example, US Pat. No. 6,590,634, US Pat. No. 5,969,441, US Pat. No. 6,208,407, a plurality of wafers. The present invention can also be applied to a multi-stage type exposure apparatus provided with a stage. Further, as disclosed in, for example, US Pat. No. 7,589,822, an exposure including a measurement stage including a measurement member (for example, a reference mark and / or a sensor) separately from the wafer stage. The present invention can also be applied to an apparatus.

  In the above embodiment, the case where the exposure apparatus 100 is a dry-type exposure apparatus that exposes the wafer W without using liquid (water) has been described. As disclosed in US Pat. No. 1,420,298, WO 2004/055803, US Pat. No. 6,952,253, and the like, an immersion optical path including illumination light path between the projection optical system and the wafer. The present invention can also be applied to an exposure apparatus that forms a space and exposes the wafer with illumination light through the liquid in the projection optical system and the immersion space.

The projection optical system of the exposure apparatus according to the present invention including the exposure apparatus of the above-described embodiment may be any of a reduction system as well as an equal magnification and an enlargement system, and the projection optical system is not only a refraction system but also a reflection system and Either a catadioptric system may be used, and the projected image may be an inverted image or an erect image.
Moreover, in the said embodiment, it is also possible to apply the so-called polarization illumination method disclosed in US Patent Application Publication No. 2006/0170901 and US Patent Application Publication No. 2007/0146676.

The light source of the exposure apparatus is not limited to the ArF excimer laser, but is a KrF excimer laser (output wavelength 248 nm), F ₂ laser (output wavelength 157 nm), Ar ₂ laser (output wavelength 126 nm), Kr ₂ laser (output wavelength 146 nm). It is also possible to use a pulse laser light source such as a super high pressure mercury lamp that emits bright lines such as g-line (wavelength 436 nm) and i-line (wavelength 365 nm). A harmonic generator of a YAG laser or the like can also be used. In addition, as disclosed in, for example, U.S. Pat. No. 7,023,610, a single wavelength laser beam in an infrared region or a visible region oscillated from a DFB semiconductor laser or a fiber laser as vacuum ultraviolet light, For example, a harmonic which is amplified by a fiber amplifier doped with erbium (or both erbium and ytterbium) and wavelength-converted into ultraviolet light using a nonlinear optical crystal may be used.

  Further, as disclosed in, for example, International Publication No. 2001/035168, an exposure apparatus (lithography system) that forms line and space patterns on a wafer W by forming interference fringes on the wafer W is provided. The exposure apparatus 100 can be employed.

  Further, as disclosed in, for example, US Pat. No. 6,611,316, two reticle patterns are synthesized on a wafer via a projection optical system, and 1 on the wafer by one scan exposure. An exposure apparatus that double exposes two shot areas almost simultaneously can be employed as the exposure apparatus 100.

  Note that the object on which a pattern is to be formed (the object to be exposed to the energy beam) in each of the above embodiments is not limited to the wafer, but other objects such as a glass plate, a ceramic substrate, a film member, or a mask blank. But it ’s okay.

  The use of the exposure apparatus is not limited to the exposure apparatus for semiconductor manufacturing, but for example, an exposure apparatus for liquid crystal that transfers a liquid crystal display element pattern to a square glass plate, an organic EL, a thin film magnetic head, an image sensor (CCD, etc.), micromachines, DNA chips and the like can also be widely applied to exposure apparatuses. Further, in order to manufacture reticles or masks used in not only microdevices such as semiconductor elements but also light exposure apparatuses, EUV exposure apparatuses, X-ray exposure apparatuses, electron beam exposure apparatuses, etc., glass substrates or silicon wafers, etc. The present invention can also be applied to an exposure apparatus that transfers a circuit pattern.

  An electronic device such as a semiconductor element includes a step of designing a function and performance of the device, a step of manufacturing a reticle based on the design step, a step of manufacturing a wafer from a silicon material, and a part of the lithography system of the above-described embodiment. A lithography step for transferring a mask (reticle) pattern onto a wafer by the exposure apparatus (pattern forming apparatus) and its exposure method, a development step for developing the exposed wafer, and exposure of portions other than the portion where the resist remains It is manufactured through an etching step for removing a member by etching, a resist removing step for removing a resist that has become unnecessary after etching, a device assembly step (including a dicing process, a bonding process, and a packaging process), an inspection step, and the like. In this case, in the lithography step, the exposure method described above is executed using the exposure apparatus that constitutes a part of the lithography system of the above embodiment, and a device pattern is formed on the wafer, so that a highly integrated device is produced. It can be manufactured with good performance.

  As described above, the illumination light source evaluation method of the present invention is suitable for evaluating the shape of an illumination light source that generates illumination light that illuminates a pattern. The illumination light source setting method of the present invention is suitable for setting the shape of the illumination light source that generates illumination light in accordance with the pattern. The exposure method of the present invention is suitable for forming a pattern on an object using illumination light. The device manufacturing method of the present invention is suitable for manufacturing an electronic device such as a semiconductor element or a liquid crystal display element.

  DESCRIPTION OF SYMBOLS 1 ... Light source, 2 ... Beam expander, 3S ... Spatial light modulator, 4 ... Relay optical system, 5 ... Fly eye lens, 6 ... Condenser optical system, 7 ... Illumination field stop, 8 ... Imaging optical system, 9 ... Bending mirror, 20 ... main controller, 80 ... luminance distribution measuring device, 100 ... exposure apparatus, IOP ... illumination system, PL ... projection optical system, PU ... projection unit, R ... reticle, RST ... reticle stage, W ... wafer , WST ... Wafer stage.

Claims (18)

An illumination light source evaluation method for evaluating an illumination light source that generates illumination light for forming a pattern on an object,
Illumination light generated by the illumination light source after the actual setting of the shape of the illumination light source in the optical system with the shape of the illumination light source obtained as a result of optimization calculation for optimizing the illumination light source being set Measuring the intensity distribution of the illumination light on the pupil plane of the optical system or its conjugate plane;
Based on a predetermined evaluation criterion regarding the measured index value of the intensity distribution and the index value of the intensity distribution of the illumination light corresponding to the target shape, the set for the target shape Evaluating the degree of coincidence of the shape of the illumination light source;
An illumination light source evaluation method including:   The illumination light source evaluation method according to claim 1, wherein the optimization calculation result optimizes a pattern and the illumination light source. The index value of the intensity distribution is the intensity distribution itself,
The illumination light source evaluation method according to claim 1, wherein the evaluation criterion is an RMS error between the measured intensity distribution and the intensity distribution of the illumination light corresponding to the target shape. The index value of the intensity distribution includes a predetermined imaging performance of an image of the pattern formed on the object when the illumination light having the intensity distribution is irradiated onto the pattern,
The evaluation criterion includes a difference between the index value corresponding to the measured intensity distribution and the index value corresponding to the intensity distribution of the illumination light corresponding to the targeted shape. The illumination light source evaluation method as described. The index value of the intensity distribution includes a predetermined imaging performance of an image of the pattern formed on the object when the illumination light having the intensity distribution is irradiated onto the pattern,
The evaluation criterion is a difference between the index value corresponding to the measured intensity distribution and the index value corresponding to the intensity distribution of the illumination light corresponding to the targeted shape, obtained for a plurality of patterns. The illumination light source evaluation method according to claim 1, comprising a statistical sum of The index value of the intensity distribution is such that the predetermined imaging performance of an image of the pattern formed on the object when the illumination light having the intensity distribution is irradiated onto the pattern is within a predetermined range. A range of the position of the object with respect to the optical axis direction of the system,
3. The evaluation criterion includes a deviation of the index value corresponding to the measured intensity distribution with respect to the index value corresponding to the intensity distribution of the illumination light corresponding to the target light source shape. The illumination light source evaluation method described in 1. The index value of the intensity distribution is calculated on the object when the illumination light having the intensity distribution is irradiated to each of a plurality of patterns while changing the position of the object with respect to the optical axis direction of the optical system. Including a range of the position of the object with respect to the optical axis direction in which a predetermined imaging performance of the image of the pattern formed on the optical axis direction is common to all of the plurality of patterns,
The evaluation criterion includes a deviation of the index value corresponding to the measured intensity distribution with respect to the index value corresponding to the intensity distribution of the illumination light corresponding to the target shape. The illumination light source evaluation method as described. The index value of the intensity distribution is the illumination given to the object by changing the position of the object in the optical axis direction of the optical system with respect to each of a plurality of patterns. When the light dose is changed and irradiated, the predetermined imaging performance of the image of the pattern formed on the object is common to all of the plurality of patterns and falls within a predetermined range. Including an area of a region determined by a range of the position of the object with respect to the optical axis direction and a range of a dose amount of the illumination light on the object;
The evaluation criterion includes a ratio between the index value corresponding to the intensity distribution of the illumination light corresponding to the target shape and the index value corresponding to the measured intensity distribution. The illumination light source evaluation method described in 1.   The illumination light source evaluation method according to claim 4, wherein the imaging performance includes an error in the size of an image of the pattern formed on the object, which is an OPE error or one of index values thereof. . The shape of the illumination light source is defined by the intensity distribution of the illumination light on the pupil plane of the optical system,
The illumination light source evaluation method according to any one of claims 1 to 9, wherein in the measurement, the illumination light source is controlled to reproduce the intensity distribution. The intensity distribution is set by an optical modulator having a plurality of mirror elements that divide and reflect the illumination light,
The illumination light source evaluation method according to claim 10, wherein in the measurement, positions of the plurality of mirror elements are individually controlled based on the light source shape obtained as a result of the optimization calculation.   The said measurement WHEREIN: The said intensity distribution is measured by light-receiving the illumination light produced | generated by the illumination light source after the said setting on the same surface as the said object, The Claim 1 any one of Claims 1-11. Illumination light source evaluation method. The optical system includes a projection optical system that projects the illumination light through the pattern onto the object,
The illumination light source evaluation method according to claim 12, wherein in the measurement, the modulation by the projection optical system is removed from the measurement result of the intensity distribution.   The program which makes a processing apparatus perform the illumination light source evaluation method as described in any one of Claims 1-13. An illumination light source setting method for setting a shape of an illumination light source for forming a pattern on an object,
Using the illumination light source evaluation method according to any one of claims 1 to 13, and evaluating the shape of the illumination light source;
Adjusting the light source based on the result of the evaluation so that a deviation of the actually measured light source shape from the target falls within an allowable range.   The program which makes a processing apparatus perform the illumination light source setting method of Claim 15.   An exposure method for irradiating illumination light from an illumination light source having a light source shape set by the illumination light source setting method according to claim 15 to form a pattern on an object. Forming a pattern on an object using the exposure method according to claim 17;
Developing the object on which the pattern is formed.