Abstract:
When it is tried to detect a microscopic defect, it is desired that the width of the above-mentioned illuminated region in the minor axis direction should be short. In the related art, although an illuminated region is formed by converging light by some means, it is not easy to form an illuminated region with a narrower width. This is because various aberrations possessed by optical elements themselves used for convergence, aberrations possessed by other optical elements disposed on optical paths, assembly errors, and the like have undesired influence on the formation of linear illumination. In the related art, sufficient consideration has not been paid to the above points. The present invention is characterized in that it includes a system for changing the wavefront of light.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an inspection apparatus that inspect defects on a substrate. 
       BACKGROUND ART 
       [0002]    In semiconductor processes, foreign substances (also referred to as defects in the broad sense of the term) on the surface of a semiconductor substrate (wafer) cause insulation failures and short circuits between wirings, and also cause insulation failures of capacitors and breakages of oxide films, and the like. The foreign substances includes substances such as created from moving parts of a carrier, device, created from human bodies, created in chemical reactions in processing devices in which process gases are used, and mixed in medicals and materials. Then these foreign substances are attached to the surface of the wafer for various reasons. In addition, in the manufacturing process of a liquid crystal display element, if a foreign substance gets mixed in a pattern of the display element, this liquid crystal display element can not be used as a display element. Further, the same can be said for the case of the manufacturing process of a printed-circuit board, and the contamination with foreign substances leads to short circuits and contact failures between patterns. Therefore, in order to manage the process yield, it becomes important to detect foreign substances on substrates such as a wafer and feed back the information to the manufacturing process. 
         [0003]    Apparatuses that are used for detecting foreign substances and the like on the above-mentioned substrates are so-called inspection apparatuses. The inspection apparatuses can be roughly classified into two types: one type is a surface inspection apparatus for inspecting mirror surface wafers, and the other type is a wafer-with-patterns inspection apparatus for inspecting wafers on which circuit patters are formed. In particular, Patent Literature 1, Patent Literature 2, and Patent Literature 3 are well known as wafer-with-patterns inspection apparatus for inspecting wafers on which circuit patters are formed. In Patent Literatures 1 to 3, an illuminated region having a two-dimensional spread in the major axis direction and the minor axis direction is formed on a substrate. Patent Literature 4 and Patent Literature 4 are well known for disclosing the related art regarding another inspection apparatus. In addition, Patent Literature 6 is well known for disclosing a technology for illuminating a substrate. Patent Literature 7 and Patent Literature 8 are well known for disclosing other technologies. 
       CITATION LIST 
     Patent Literature 
       [0004]    Patent Literature 1: U.S. Pat. No. 7,098,055 
         [0005]    Patent Literature 2: U.S. Pat. No. 6,608,676 
         [0006]    Patent Literature 3: United States Patent Application Publication No. 2009/0059216 
         [0007]    Patent Literature 4: Japanese Unexamined Patent Application Publication No. 2011-69769. 
         [0008]    Patent Literature 5: Japanese Unexamined Patent Application Publication No. 2008-58111 
         [0009]    Patent Literature 6: Japanese Unexamined Patent Application Publication No. Hei8 (1996)-304732 
         [0010]    Patent Literature 7: U.S. Pat. No. 7,535,561 
         [0011]    Patent Literature 8: Japanese Unexamined Patent Application Publication No. Hei4 (1992)-350613 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0012]    When it is tried to detect a microscopic defect, it is desired that the width of the above-mentioned illuminated region in the minor axis direction should be short. In the related art, although an illuminated region is formed by converging light by some means, it is not easy to form an illuminated region with a narrower width. This is because an aberration that cannot be removed for some design reason, a wavefront aberration owing to the processing accuracies of optical elements themselves that are used for convergence, and the like have undesired influence on the formation of linear illumination. In the related art, sufficient consideration has not been paid to the above point. 
       Solution to Problem 
       [0013]    The present invention is characterized in that it includes a system for changing the wavefront of light. 
       Advantageous Effects of Invention 
       [0014]    According to the present invention, a more highly sensitive inspection can be performed than the inspection according to the related art. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0015]      FIG. 1  is a diagram for explaining a reason why an illumination width narrower than the focal depth of an oblique detection system is required. 
           [0016]      FIG. 2  is a diagram for explaining the reason why an illumination width narrower than the focal depth of an oblique detection system is required (continued from  FIG. 1 ). 
           [0017]      FIG. 3  is a schematic block diagram showing a defect inspection apparatus according to a first embodiment. 
           [0018]      FIG. 4  is a diagram for explaining an illumination system  300  in detail. 
           [0019]      FIG. 5  is a front view of a deformable mirror  309 . 
           [0020]      FIG. 6  is a cross-section view of the deformable mirror  309 . 
           [0021]      FIG. 7  is a diagram for explaining a deformable mirror including electrostatic actuators. 
           [0022]      FIG. 8  is a diagram for explaining a procedure of illumination reshaping (No. 1). 
           [0023]      FIG. 9  is a diagram for explaining the procedure of illumination reshaping (No. 2) 
           [0024]      FIG. 10  is a diagram for explaining the procedure of illumination reshaping (No. 3) 
           [0025]      FIG. 11  is a flowchart for explaining the procedure of illumination reshaping. 
           [0026]      FIG. 12  is a diagram for explaining a second embodiment. 
           [0027]      FIG. 13  is a diagram for explaining a third embodiment. 
           [0028]      FIG. 14  is a diagram for explaining a fourth embodiment. 
           [0029]      FIG. 15  is a diagram for explaining a fifth embodiment. 
           [0030]      FIG. 16  is a diagram for explaining a sixth-embodiment. 
           [0031]      FIG. 17  is a diagram for explaining a seventh embodiment. 
           [0032]      FIG. 18  is a diagram for explaining an eighth embodiment. 
           [0033]      FIG. 19  is a diagram for explaining a ninth embodiment. 
           [0034]      FIG. 20  is a diagram for explaining a tenth embodiment (No. 1). 
           [0035]      FIG. 21  is a diagram for explaining the tenth embodiment (No. 2). 
           [0036]      FIG. 22  is a diagram for explaining the tenth embodiment (No. 3). 
           [0037]      FIG. 23  is a diagram for explaining an eleventh embodiment. 
           [0038]      FIG. 24  is a flowchart for explaining the eleventh embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0039]    Embodiments of the present invention will be described with reference to the accompanying drawings hereinafter. 
       First Embodiment 
       [0040]    At the beginning the explanation of a first embodiment, the reason why an illuminated region with a narrow width in the minor axis direction is required will be explained first.  FIG. 1  and  FIG. 2  show the reason why an illumination width narrower than the focal depth of an oblique detection system is required when the oblique detection system is used in a defect inspection apparatus. 
         [0041]      FIG. 1  is a diagram showing a normal image focus relationship in the case where a later-mentioned illuminated region  209  is reshaped so as to have its width equal to or narrower than the after-mentioned focused focal region  202  in an inspection apparatus using an oblique detection system  100 . A focused focal plane  103  shows a region that is included by the focused focal plane and the focal depth at the object side of the oblique detection system  100 . The focused focal region  202  is a region where the focused focal plane  103  and the surface of an inspection target  200  intersect with each other. In  FIG. 1 , illumination light  301  emitted from an illumination system  300  is reshaped into linear light with its width equal to or narrower than the focused focal region  202 , and the reshaped illumination light is irradiated onto the focused focal region  202 . In this case, because the reshaped illumination light does not illuminate a defocused region  203 , only scattered light  201  from the focused focal region  202  is created, the scattered light is focused into an image by an oblique detection optical system  101  including an objective lens, a spatial filter, an imaging lens, and the like. The image built up in an image focus position  104  is received by the surface of a one-dimensional sensor  102 . In this state, a focused image can be obtained by scanning the inspection target  200 . 
         [0042]      FIG. 2  is a diagram showing an image focus relationship in the case where the illuminated region  209  is wider than the focused focal region  202  in the inspection apparatus using the oblique detection system  100 . In  FIG. 2 , the illumination light  301  emitted from the illumination system  300  forms the illuminated region  209  on the inspection target  200 . In  FIG. 2 , in the case where the illuminated region  209  is larger than the focused focal region  202 , the defocused region  203  is also illuminated. In this case, not only the scattered light  201  created from the focused focal region  202 , but also scattered light  208  created from a foreign substance or a pattern  207  existing on the defocused region  203  is received in a defocused state by the one-dimensional sensor  102 , which leads to the degradation of the detected image. 
         [0043]    The above is the reason why it is desired that linear illumination with its width equal to or narrower than the focused focal region  202  should be used in the case where the oblique detection system  100  is used. 
         [0044]    Next, a defect inspection apparatus according to this embodiment will be explained below.  FIG. 3(   a ) is a schematic block diagram of the defect inspection apparatus according to this embodiment. In  FIG. 3(   a ), a defect inspection apparatus  1000  includes: an illumination system  300 ; an oblique detection system  100 ; an upward detection system  800 ; a stage  400  on which an inspection target  200  is disposed to be scanned by illumination light; a one-dimensional sensor  102  (a time delay integration sensor (TDI sensor), a charge-coupled device, or the like); a one-dimensional sensor  802 ; a calculation processing system  700  that processes images obtained by the one-dimensional sensors  102  and  802  in order to detect defects; a two-dimensional sensor  107 ; a two-dimensional sensor  807 ; a display device  701  for displaying images obtained by the two-dimensional sensors  107  and  807 ; an optical branching component  106 ; and a reference chip  205  (a chip in which standard circuit patterns are formed) that is used for detecting the focused focal position of the oblique detection system  100 . The reference chip  205  is disposed on the stage  400 . In addition, as the reference chip, standard particles that are polystyrene latex balls attached onto a mirror surface substrate can be used. 
         [0045]    The calculation processing system  700  processes the image  500  of the reference chip  205  obtained by the two-dimensional sensor  107 , detects the focused focal recognition position  502  of the oblique detection system  100 , and controls the stage  400  and the illumination system  300 . In an actual inspection, the calculation processing system  700  compares the image of a chip (an image to be inspected) on the inspection target  200  obtained from at least one of the oblique detection system  100  and the upward detection system  800  with the reference image (the image of chips lying next to the chip whose image is to be inspected) on the inspection target  200 , and performs threshold processing on the comparison result in order to find a defect on the inspection target  200 . This defect detection operation is performed in synchronization with the scanning operation in x and y directions performed by the stage  400 . The comparison of an inspection image with a reference image and threshold processing are performed in the units of the so-called dies or in the units of the so-called cells. In addition, if an inspection apparatus includes plural optical detection systems as is the case with this embodiment, there is a case where the comparison of an inspection image with a reference image and threshold processing are performed in the units of optical detection systems in the inspection apparatus. Further, there is a case where, after the comparison and the threshold processing are performed in units of the detection systems, defect detection is performed using the so-called characteristic quantities, that is, the defect detection is performed by integrally processing the characteristic quantities. These processes may be performed by a processing system separately installed instead of the calculation processing system  700 . The control over the stage  400  and the illumination system  300  may also be performed by a control unit separately installed. 
         [0046]    The coordinate system of the defect inspection apparatus  1000  is defined so that the direction of the z-axis is the direction of the normal line  204  of the upper surface of the inspection target  200 , the direction of the x-axis is the direction of the scanning of the inspection target  200 , and the direction of the y-axis is perpendicular to both directions of the x-axis and z-axis. 
         [0047]    The stage  400  is configured to be movable in four directions, that is, the directions of the x-axis, y-axis, z-axis, and θ-axis. 
         [0048]    The oblique detection system  100  includes: a detection optical system  101  having an objective lens  105  and an imaging lens  109 ; the one-dimensional sensor (a TDI sensor or a one-dimensional CCD sensor)  102 ; the optical branching component  106 ; and the two-dimensional sensor  107 . The oblique detection system  100  mainly detects scattered light  201  that scatters in the oblique direction relative to the normal line  204 . 
         [0049]    If the one-dimensional sensor  102  is a TDI sensor and is capable of taking an image in the same way as a two-dimensional sensor does, the optical branching component  106  and the two-dimensional sensor  107  can be omitted. In addition, a spatial filter can be inserted on a Fourier transform plane formed between the objective lens  15  and the imaging lens  109  in order to shield diffracted light arriving from a repeated pattern of the inspection target  200  and remove the repeated pattern. 
         [0050]    The one-dimensional sensor  102  is disposed in such a way that the longitudinal direction (which is perpendicular to the scanning direction) of the sensor is set approximately parallel with a direction that is the same direction in which the y-axis of the inspection target is projected by the oblique detection optical system  101 . In addition, the light-receiving surface of the one-dimensional sensor  102  is disposed approximately perpendicular to the optical axis  108  of the oblique detection system  100 . 
         [0051]    A detection system moving unit  120  can move the oblique detection system  100 . 
         [0052]    The upward detection system  800  includes: an upward detection optical system  801  having an objective lens  805  and an imaging lens  809 ; the one-dimensional sensor (a TDI sensor or a one-dimensional CCD sensor)  802 ; an optical branching component  806 ; and the two-dimensional sensor  807 . The upward detection system  800  detects scattered light that scatters in the direction of the normal line  204 . If the one-dimensional sensor  802  is a TDI sensor and is capable of taking an image in the same way as a two-dimensional sensor does, the optical branching component  806  and the two-dimensional sensor  807  can be omitted. In addition, a spatial filter may be inserted on a Fourier transform plane formed between the objective lens  805  and the imaging lens  809  in order to shield diffracted light arriving from a repeated pattern of the inspection target  200  and remove the repeated pattern. 
         [0053]    When the focused focal position of the oblique detection system  100  is detected, the reference chip  205  is disposed in the inspection position, and while an inspection operation is performed, the reference chip  205  is evacuatedly disposed in a position so that the reference chip  205  disposed there does not disturb the inspection operation. For example, the reference chip  205  is installed on the same horizontal plane as the inspection target  200  is installed relative to the stage  400 , and when the focused focal position of the oblique detection system  100  is detected, the reference chip  205  is moved to a predefined position by moving the stage  400 . In addition, the reference chip  205  is disposed within the visual field of an illumination observation system  370 , which will be described later, when an illuminated shape  901  is observed. 
         [0054]    As the optical branching component  106 , a half mirror or a prism can be used. Alternatively, a mirror, which is taken into or taken out from an optical path in order to switch the optical path and lead the scattered light  201  to the two-dimensional sensor  107  at the time when the focused focal position is detected, can be used as the optical branching component  106 . Similarly, as the optical branching component  806 , a half mirror or a prism can be used. Alternatively, a mirror, which is taken into or taken out of an optical path in order to switch the optical path and lead the scattered light to the two-dimensional sensor  807  at the time when the inspection target  200  or the reference chip  205  is observed, and when the illumination light  301  is observed, may be used as the optical branching component  806 . 
         [0055]    In this embodiment, the illumination system  300  that illuminates the inspection target  200  is moved relative to the inspection target  200  by an illumination system moving unit  350 . 
         [0056]    Here, several variations can be thought of about the relationship among the illumination system  300 , the inspection target  200 , and the oblique detection system  100 . One variation is shown in  FIG. 3(   b ). In  FIG. 3(   b ), the illumination system  300  converges the illumination light  301  in the y scanning direction of the stage  400 , and forms a linear illuminated region on the inspection target  200 . In this case, the longitudinal direction of the illuminated region coincides with the y scanning direction of the stage  400 . In addition, in the case of  FIG. 3(   b ), two oblique detection optical systems  100  are disposed, and these two oblique detection optical systems  100  are symmetrically disposed about the y scanning direction of the stage  400 , and these oblique detection optical systems  100  are also symmetrically disposed about an incident plane determined by the normal line of the inspection target  200  and the optical axis of incident light. Another variation is shown in  FIG. 3(   c ). In  FIG. 3(   c ), the illumination system  300  converges the illumination  301  light in such a direction that an angle between a projected line obtained by projecting the optical axis of light radiated from the illumination system  300  onto the inspection target  200  and the y scanning direction of the stage  400  forms an azimuthal angle θ. In the case of  FIG. 3(   c ), although two oblique detection systems  100  are symmetrically disposed about the y scanning direction of the stage  400 , these oblique detection systems  100  are not symmetrically disposed about the incident plane. 
         [0057]    The defect inspection apparatus according to this embodiment is configured to be able to inspect the inspection target  200  using the upward detection system  800  and the oblique detection system  100  at the same time. For example, in order to it possible to detect the same position of the inspection target by both detection systems, this defect inspection apparatus includes the oblique detection system moving unit  120  that moves the oblique detection system  100  relative to the inspection target. Alternatively, such a driving mechanism as the oblique detection system moving unit  120  may be included by the upward detection system  800  side, or such a driving mechanism may be included by each of the upward detection system  800  and oblique detection system  100 . 
         [0058]    Next, the illumination system  300  will be described in detail with reference to  FIG. 4 .  FIG. 4  is a diagram for explaining the illumination system  300  and the illumination observation system  370  according to this embodiment. The illumination system  300  includes: a deformable mirror  309  that reshapes the wavefront  306  of illumination light  308  radiated from a light source into an arbitrary wavefront  307 , and reflects the illumination light  308 ; a mirror  312  that is a reflection component; an optical path branching component/optical path switching component  313 ; a mirror  314  that is a reflection component; a wavefront sensor  305  that measures the wavefront  307  of the incident light  308  that is reflected or branched by the optical path branching component/optical path switching component  313 ; a control means  341  that creates data for driving the deformable mirror  309  using the wavefront measured by the wavefront sensor  305 ; a driving means  342  that drives the deformable mirror  309  using the data from the control means  341 ; and an illumination reshaping component  303  that reshapes the illumination light into linear illumination light. In this embodiment, illumination light  321  that has passed through such an illumination system  300  is irradiated onto an inspection target  200 . In addition, the control component  341  and the driving component  342  can be provided separately from each other, or a combination of both components can be provided as one component. Here, a wavefront can be represented, for example, as a plane that intersects with the optical axis of light, and more concretely, can be represented as a plane perpendicular to the optical axis of the light. 
         [0059]    The illumination system  300  will be described more concretely. After entering the deformable mirror  308 , the illumination light  308 , which is emitted from the light source and whose wavefront  306  is flat, is reflected. The wavefront of the illumination light  308  reflected by the deformable mirror  308  is changed from the substantially flat wavefront  306  into a wavefront  307  having undulation. The illumination light  308  reflected by the deformable mirror  308  is reflected by the reflection component  314 , and enters the optical path branching component/optical path switching component  313 . In this case, the undulation of the wavefront  307  represents a phase that is the inverse of the phase of the aberration of the illumination reshaping component  303 . The wavefront of the light branched by the optical path branching component/optical path switching component  313  is observed by wavefront sensor  305 . The wavefront observed by the wavefront sensor  305  is input into the control component  341 . The light passing through the optical path branching component/optical path switching component  313  is reflected by the reflection component  312 , and enters the illumination reshaping component  303 . The illumination reshaping component  303  converges the light in the direction shown by an arrow  3002  (in the direction perpendicular to the plane of the page). The illumination reshaping component  303  does not converge the light in the direction shown by an arrow  3001  that is orthogonal to the arrow  3002 , and irradiates the light as it is, that is, as parallel light. As a result, the light is converged in the direction shown by the arrow  3002  on the reference chip  205  (so as to have a short axis), and a substantially linear illuminated region that has a long axis in the direction shown by the arrow  3001  is formed. In addition, in this embodiment, an elevation angle at which the light is irradiated onto the reference chip  205  (or onto the inspection target  200 , of course) can be changed by rotating the reflection component  312  in the direction shown by an arrow  3004  using some driving means such as a motor and by moving the illumination reshaping component in the direction shown by an arrow  3003  (in the direction parallel with the optical axis of the illumination light). Here, there are other methods that change the illumination elevation angle, and these methods will be explained in embodiments 3 to 6. 
         [0060]    As an example of the illumination reshaping component  303 , cylindrical lens, a cylindrical mirror, a diffraction optical element, a combination of one or some of the above elements and an optical lens, and the like are conceivable. In addition, as an example of arrangement of a cylindrical lens or a cylindrical mirror, there is an arrangement in which the cylindrical lens or cylindrical mirror is arranged so that the principal plane of the cylindrical lens or cylindrical mirror is parallel with the surface of the inspection target  200 . As an illumination method using the illumination reshaping component  303 , there is a method in which linear illumination is formed in such a way that the linear illumination intersects with an incident plane determined by the normal line of the inspection target  200  and the optical axis of the incident light, or a method in which the linear illumination is formed in the incident plane. As long as linear illumination can be formed on the inspection target  200 , various methods using the illumination reshaping component  303  can be adopted. 
         [0061]    The illumination reshaping component  303  converges the incident light, and creates the illumination light  321 . In the case where the illumination light  321  is adjusted, the illumination light  321  is irradiated onto the reference chip  205 . A linear illuminated region is formed on the reference chip by the illumination light  321 . Scattered light from the reference chip is focused into an image and detected by the illumination observation system  370  that includes an objective lens, an imaging lens, and a one-dimensional sensor. In this case, diffracted light can be used instead of the scattered light, and a two-dimensional sensor or the so-called beam profiler can be used instead of the one-dimensional sensor. The detected image is input into the control component  341 . The control component  341  creates data for driving the deformable mirror  309  using the wavefront observed by the wavefront sensor  305  and the image observed by the illumination observation system  370 . (The data can be read out from a database in which candidate data are stored.) The data created by the control component  341  is changed into a signal used by the driving component  342  for driving the deformable mirror  309 . The deformable mirror  309  is driven in accordance with the data from the control component  341 . As a result, the wavefront  307  is changed into an arbitrary wavefront, and the shape of the linear illumination formed by the illumination light  321  is also changed. 
         [0062]    Next, the deformable mirror  309  according to this embodiment will be described in detail with reference to  FIG. 5 ,  FIG. 6 , and  FIG. 7 .  FIG. 5  is a front view of the deformable mirror  309  according to this embodiment. As shown in  FIG. 5 , the deformable mirror  309  according to this embodiment includes a reflection board  3091  having two-dimensional spread and plural actuators  3092  disposed on the rear surface of the reflection board  3091 .  FIG. 6  is a cross-section view of the deformable mirror  309  according to this embodiment. The actuators  3091  can press the rear surface of the reflection board  3091 . These behaviors of the actuators  3092  makes it possible to change the state of the reflection surface of the reflection board  3091  (for example, the state of the undulation of the reflection surface) arbitrarily, so that the wavefront of light, which enters the reflection board  3091  and is reflected by the reflection board  3091 , can be changed arbitrarily. As a concrete example of the actuator  3092 , an elastic piezoelectric element, a linear actuator, or the like can be used. Here, if the actuators  3092  are piezoelectric elements, the actuators  3092  have to include a power supply for driving the piezoelectric elements. 
         [0063]    The deformable mirror  309  having a structure different from the above-described structure can be also conceivable.  FIG. 7  is a diagram for explaining a deformable mirror including electrostatic actuators.  FIG. 7(   a ) shows plural electrostatic actuators  3093  disposed on the rear surface of the reflection board  3091 . These actuators can be fabricated using a MEMS process or the like. In addition, the actuators can be arranged in a lattice-shaped pattern, in a radial pattern, or in any other pattern. Because the strokes of the electrostatic actuators  3093  are small and the spatial resolutions of the electrostatic actuators  3093  are high, the electrostatic actuators  3093  are useful for high-accurate driving of the deformable mirror  309 . In addition, as shown in  FIG. 7(   b ), a hybrid scheme that is a combination of a scheme shown in  FIG. 6  and the scheme shown in  FIG. 7  can be used. In the hybrid scheme shown in  FIG. 7(   b ), the plural electrostatic actuators  3093  are disposed on the rear surface of the reflection board  3091 . In addition, the hybrid scheme includes the actuators  3092  that push the rear surface of a board  3094  disposed so as to face the rear surface of the reflection board  3091 . In the hybrid scheme, the linear actuators  3092 , each of which has a long stroke and a low spatial resolution, roughly drive the reflection board  3091  (perform rough driving), and the electrostatic actuators  3093 , each of which has a short stroke and a high spatial resolution, perform driving more finely than the linear actuators  3092  does. In this way, the hybrid scheme has a wider driving range than the other two schemes. 
         [0064]    Here, the wavefront sensor  305  can be a Shack-Hartmann sensor, a curvature sensor, or the like as long as it can measure the shape of a wavefront coming into the wavefront sensor  305 . 
         [0065]    Next, the procedure of illumination shaping according to this embodiment will be described with reference to  FIG. 8  to  FIG. 11 . First, in  FIG. 8(   a ), the control component  341  obtains the information of a wavefront (this wavefront can be referred to, for example, as a first wavefront) from the wavefront sensor  305  (at step  1101  in  FIG. 11) . The deformable mirror  309  is driven so that the wavefront  8001  of light entering the illumination reshaping means  303  becomes approximately in no aberration state using the information from the wavefront sensor  305  (at step  1102  in  FIG. 11 ). 
         [0066]    Afterward, the incident light  308  with the wavefront  8001  is irradiated onto the reference chip  205  after being reshaped in a linear shape by the illumination reshaping means  303 . The illuminated shape  901  at this moment is observed by the illumination observation system  307  (at step  1103  in  FIG. 11 ). As described above, by observing the illuminated shape  901  under the condition that the wavefront  8001  of the light is approximately in no aberration state, the state of undesired factors for light convergence such as an aberration  8010  that can not be removed for some design reason as shown in  FIG. 8(   b ) and a wavefront aberration  8020  owing to the processing accuracy of the illumination reshaping means  303  as shown in  FIG. 8(   c ) can be obtained. In addition, if the illumination reshaping means  303  is a cylindrical lens  8030  as shown in  FIG. 8(   d ), there is fear that especially the shapes of both ends of the longitudinal direction of an illuminated region  8040  get turbulent. 
         [0067]      FIG. 9  shows an optical simulator model in which the reference chip  205  is disposed on the object plane, the illumination reshaping means  303  and the illuminated shape  902  are modeled, and the image plane is set to an incident wavefront  904 . The control component  341  disposes a light source model  902  based on the illuminated shape  901  as a light source on the reference chip  205  in accordance with the model in  FIG. 9 , lets the light from the light source model  902  to enter the theoretical model  903  of the illumination reshaping component  303 , and calculates a wavefront  904  that has passed through the theoretical model  903  (at step  1104  in  FIG. 11 ). 
         [0068]    Subsequently, as shown in  FIG. 10(   a ), the control component  341  creates data for changing the wavefront  8001 , which is observed by the wavefront sensor  305  and in no aberration state, into a wavefront having an inverse phase relative to the wavefront  904  that has passed through the theoretical model  903 , wherein the wavefront  904  is a wavefront onto which the factors, which are undesired for light convergence, are superimposed (at step  1105  in  FIG. 11) . The deformable mirror  309  is driven on the basis of these data (at step  1106  in  FIG. 11 ), and the deformable mirror  309  changes the wavefront  8001 , which is approximately in no aberration state, into a wavefront  1001  having an inverse phase relative to the wavefront  904  that has passed through the theoretical model  903  as a wavefront of light entering the illumination reshaping means  303 , wherein the wavefront  1001  can be referred to, for example, as a second wavefront. The light having the wavefront  1001  is irradiated onto the reference chip  205  as linear illumination via the illumination reshaping means  303 . An illuminated shape  1002  on the reference chip  205  is observed by the illumination observation system  370  (at step  1107  in  FIG. 11 ). The control component  341  compares the observation result of the illuminated shape  901  shown in  FIG. 8  with the observation result of the illuminated shape  1002 , and if a desired state (for example, a state in which the linear illumination is reshaped so that its width is equal to or narrower than the width of the focused focal region as shown in  FIG. 1 ) is verified (at step  1108  in  FIG. 11 ), the reshaping of the illuminated region is finished (at step  1109  in  FIG. 11 ). For example, as shown in  FIG. 10(   b ), if the illumination reshaping means  303  that converges the light reflected by the deformable mirror  309  is the cylindrical lens  8030 , because the cylindrical lens  8030  converges the illumination light  321 , the shapes of both ends of the longitudinal direction of the illuminated region  8040 , which is formed on the inspection target  200 , does not get turbulent, so that the desired linear illumination has to be formed. If the desired state can not be obtained, it is necessary to repeat step  1106  in  FIG. 11  until the desired shape is obtained. Alternatively, it is all right if the flow goes back to step  1105  in  FIG. 11  to create the data again. An actual inspection shown in  FIG. 11  is performed after this illumination shaping is finished (at step  1110  in  FIG. 11) . In other words, because the state of undesired factors for light convergence can be obtained at step  1103 , by irradiating light whose wavefront is optically inverse to the wavefront onto which the undesired factors for light convergence is superimposed (for example, the wavefront onto which the undesired factors for light convergence are superimposed can be referred to as a wavefront having the inverse phase), it can be expected that the desired linear illumination is formed. 
         [0069]    Thanks to the above procedure, the influence, which is caused by an aberration that can not be removed for some design reason, a wavefront aberration owing to the processing accuracies of optical elements themselves that are used for convergence, and the like, can be reduced, so that it becomes possible to make the state of an illuminated shape  905  come near to a preferred state for the inspection (for example, a state in which the linear illumination is reshaped so that its width is equal to or narrower than the width of the focused focal region as shown in  FIG. 1 ). According to this embodiment, the wavefront aberration of illumination light can be reduced, and the line width of an illuminated region can be miniaturized, with the result that the sensitivity of the defect inspection performed by the oblique detection system can be improved. 
         [0070]    Although the example in which the illumination reshaping is automatically adjusted by the control unit  341  has been described above, the illumination reshaping may also be configured to be performed by an operator who manually performs the operations of the control unit  341  using various display devices and input devices. Alternatively, the illumination reshaping may also be configured in such a way that a part of the above illumination reshaping procedure is performed by the control unit  341 , and the other part is performed by an operator. In addition, it is also all right that at least one of the upward detection system  800  and the oblique detection system  100  includes the function of the observation optical system  370 . 
       Second Embodiment 
       [0071]    Next, a second embodiment will be described. In the description about the second embodiment, parts of the second embodiment different from those of the first embodiment will mainly be described. The first embodiment includes the deformable  309  mirror that is an example of system for changing a wavefront, and the illumination reshaping component  303  that forms linear illumination. In other words, it can be said that optical systems or optical elements independent from each other are respectively in charge of the function for changing a wavefront and the function for forming linear illumination. This embodiment is characterized in that one optical system is in charge of both function for changing a wavefront and function for forming linear illumination. 
         [0072]    This embodiment will be described more concretely.  FIG. 12  is a diagram for explaining this embodiment. This embodiment allows a deformable mirror  309  itself to include the function for reshaping illumination (that is, the function for forming linear illumination) without using the illumination reshaping component  303  of the first embodiment. In other words, for example, as shown in  FIG. 12 , plural actuators  3092  disposed on the rear surface of a reflection component  601  are driven, so that the reflection component  601  forms the reflection plane of a cylindrical mirror. In this case, it can be said that the deformable mirror  309  according to this embodiment is a deformable cylindrical mirror including both function for changing a wavefront and function for forming linear illumination. Such a deformable mirror  309  is especially effective for forming linear illumination using light of a short wavelength. In addition, plural deformable mirrors  309  according to this embodiment may also be disposed in the optical path of an illumination system. Further, a total reflection illumination optical system can be configured using the deformable mirrors  309  and plural reflection optical elements such as mirrors. Here, a hybrid type deformable mirror as shown in  FIG. 7(   a ) can be used as the deformable mirror  309  according to this embodiment. 
       Third Embodiment 
       [0073]    Next, a third embodiment will be described below. In order to highly sensitively detect various defects existing on an inspection target, an optimal illumination condition (determined by, for example, an azimuthal angle, an elevation angle, a wavelength, and the polarization of light irradiated onto the inspection target) varies in accordance with various kinds of defects. This embodiment is achieved with this point in mind, and characterized in that it includes an illumination condition changing system in which a deformable mirror changes the wavefront of light in accordance with the variation of the illumination condition. In the description about the third embodiment, parts of the third embodiment different from those of the first embodiment will mainly be described. 
         [0074]      FIG. 13  is a diagram for explaining this embodiment. This embodiment includes a first elevation angle illumination system  1201  for forming linear illumination on an inspection target  200  at a first elevation angle  1205  and a second elevation angle illumination system  1202  for forming linear illumination on the inspection target  200  at a second elevation angle  1206  that is lower than the first elevation angle  1205  in the optical path between a deformable mirror  309  and a illumination reshaping component  303 . In addition, this embodiment includes a reflection component  1203 , such as a mirror, for guiding the light reflected, by the deformable mirror  309  to the first elevation angle illumination system  1201  or to the second elevation angle illumination system  1202  between the first elevation angle illumination system  1201  and the second elevation angle illumination system  1202 . The mirror can be moved in the direction shown by an arrow  1204 . The first elevation angle illumination system  1201  includes an optical path branching component/optical path switching component  313  for guiding the light reflected by the reflection component  1203  to a wavefront sensor  305 , and the reflection component  312 , such as a mirror, for guiding the light that passes through the optical path branching component/optical path switching component  313  to the illumination reshaping component  303 . The second elevation angle illumination system  1202  includes an optical path branching component/optical path switching component  323  for guiding the light reflected by the reflection component  1203  to the wavefront sensor  305 , and a reflection component  322 , such as a mirror, for guiding the light that passes through the optical path branching component/optical path switching component  323  to the illumination reshaping component  303 . 
         [0075]    In this embodiment, in the case where the reflection component  1203  guides the light to the first elevation angle illumination system  1201 , the deformable mirror  309  adjusts a reflection wavefront  307  so that the width of linear illumination formed by illumination light  311  is reshaped at the first elevation angle  1205  so as to be equal to or narrower than the width of the focused focal region. In addition, in the case where the reflection component  1203  guides the light to the second elevation angle illumination system  1202 , the deformable mirror  309  adjusts the reflection wavefront  307  so that the width of linear illumination formed by illumination light  321  is reshaped at the second elevation angle  1206  so as to be equal to or narrower than the width of the focused focal region. 
         [0076]    The adjustment of the wavefront can be performed in the following way. In advance of the inspection, the adjustment method disclosed in the first embodiment is performed in both cases where linear illumination is formed on the inspection target  200  at the first elevation angle  1205  and where linear illumination is formed on the inspection target  200  at the second elevation angle, and first data for forming the linear illumination on the inspection target  200  at the first elevation angle  1205  and second data for forming the linear illumination on the inspection target  200  at the second elevation angle  1206  are respectively stored in the control component  341 . In the inspection, after the first data or the second data is read out in accordance with the movement of the reflection component  1203 , the deformable mirror  309  may be driven using the read-out data. Other parts of this embodiment are the same as those of the first embodiment. According to this embodiment, the illumination elevation angle can be changed, so that it becomes possible to perform a more highly sensitive inspection. In addition, in this embodiment, a newly installed reflection component  1207  may be taken into or taken out of the optical path of the second elevation angle illumination system  1202  in the direction shown by an arrow  1208  while the reflection component  1203  is fixed in the optical path of the first elevation angle illumination system  1201  instead of being moved. 
       Fourth Embodiment 
       [0077]    Next, a fourth embodiment will be described with reference to  FIG. 14 . In the third embodiment, an example in which the illumination elevation angle is changed has been described. This embodiment shows an example in which plural pieces of light are irradiated at plural elevation angles substantially at the same time. In the description about this embodiment, parts of the fourth embodiment different from those of the first and second embodiments will mainly be described. 
         [0078]    This embodiment is characterized in that it includes an optical path branching component  1305  and a first deformable mirror  1303  that reflects light that passes through the optical path branching component  1305  instead of the reflection component  1203  described in the third embodiment. 
         [0079]    This embodiment will be described more concretely below. In this embodiment, illumination light  308  with an incident wavefront  306  is reflected by a second deformable mirror  1304 . The light whose wavefront is changed into a reflection wavefront  307  by the deformable mirror  1304  enters the optical path branching component  1305 . The light that passes through the optical path branching component  1305  enters the first deformable mirror  1303 . The light whose wavefront is further changed by the first deformable mirror  1303  enters a first elevation angle illumination system  1301  for forming linear illumination on the inspection target  200  at a first elevation angle  1307 . The light reflected by the optical path branching component  1305  enters a second elevation angle illumination system  1302  for forming linear illumination on the inspection target  200  at a second elevation angle  1308  that is lower than the first elevation angle  1307 . The configurations of the first elevation angle illumination system  1301  and the second elevation angle illumination system  1302  are respectively the same as those of the first elevation angle illumination system and the second elevation angle illumination system shown in the third embodiment. 
         [0080]    In this embodiment, the first deformable mirror  1303  adjusts a reflection wavefront  1309  so that the width of linear illumination formed by illumination light  311  is reshaped at the first elevation angle  1307  so as to be equal to or narrower than the width of the focused focal region. The second deformable mirror  1304  adjusts the reflection wavefront  307  so that the width of linear illumination formed by illumination light  321  is reshaped at the second elevation angle  1308  so as to be equal to or narrower than the width of the focused focal region. 
         [0081]    In this embodiment, the adjustment of linear illumination can be performed in the following way. (1) First, the optical path of the first elevation angle illumination system  1301  is shielded by a shutter  1306 , and the wavefront of light that passes through the optical path branching component/optical path switching component  323  in the second elevation angle detection system  1302  is observed by the wavefront sensor  305 . (2) Subsequently, using the adjustment method disclosed in the first embodiment, the reflection wavefront  307  is adjusted so that the width of linear illumination irradiated at the second elevation angle  1308  is reshaped so as to be equal to or narrower than the width of the focused focal region. (3) Next, the optical path of the second elevation angle illumination system  1302  is shielded by the shutter  1306 , and the wavefront of light that passes through the optical path branching-component/optical path switching component  313  in the first elevation angle detection system  1301  is observed by the wavefront sensor  305 . (4) Subsequently, using the adjustment method disclosed in the first embodiment, the reflection wavefront  1309  is adjusted so that the width of linear illumination irradiated at the first elevation angle  1307  is reshaped so as to be equal to or narrower than the width of the focused focal region. 
         [0082]    In the actual inspection, first data for forming the linear illumination on the inspection target  200  at the first elevation angle  1307  and second data for forming the linear illumination on the inspection target  200  at the second elevation angle  1308  are respectively stored in a control component  341 , and after the first data and the second data are read out, the first deformable mirror  1303  and the second deformable mirror  1304  can be driven respectively using the read-out first data and second data. 
         [0083]    According to this embodiment, pieces of light are irradiated at plural elevation angles onto the inspection target  200  at the same time, so that it becomes possible to perform a more highly sensitive inspection. 
       Fifth Embodiment 
       [0084]    A fifth embodiment will be described below.  FIG. 15  is a diagram for explaining the fifth embodiment. The fifth embodiment is characterized in that the deformable cylindrical mirror explained in the second embodiment is used instead of the illumination reshaping component  303  and the deformable mirror  309  that are explained in the third embodiment, and pieces of light are selectively irradiated onto the inspection target at plural elevation angles. In the fifth embodiment, a more highly sensitive inspection can be performed using light of a shorter wavelength. 
       Sixth Embodiment 
       [0085]    Next, a sixth embodiment will be described below.  FIG. 16  is a diagram for explaining the sixth embodiment. The sixth embodiment is characterized in that a first deformable cylindrical mirror  1601  and a second the deformable cylindrical mirror  1602 , such as explained in the second embodiment, are used instead of the illumination reshaping component  303 , the first deformable mirror  1303 , and the second deformable mirror  1304  that are explained in the fourth embodiment, and pieces of light are irradiated approximately at the same time onto the inspection target at plural elevation angles. In the sixth embodiment, a more highly sensitive inspection can be performed using light of a shorter wavelength. In the fourth embodiment to the seventh embodiment, although the descriptions have been made under the assumption that one illumination reshaping component  303  is used, linear illumination may also be formed at plural elevation angles by preparing the same number of the illumination reshaping components  303  as the number of the elevation angles at which pieces of illumination light are irradiated. 
       Seventh Embodiment 
       [0086]    A seventh embodiment will be described below. In the above described embodiments, it can be said that, for example, it is preferable for the optical location of the wavefront sensor  305  to be near to linear illumination. This is because to observe a wavefront at a location nearer to the linear illumination makes it possible to observe the state of the wavefront that is just before the actual formation of the linear illumination. This embodiment is achieved with this point in mind. 
         [0087]      FIG. 17  is a diagram for explaining this embodiment. In the first embodiment to the sixth embodiment, the optical branching component/optical path switching component and the wavefront sensor are disposed in the optical path located before the illumination reshaping component  303  (in other words, in the optical path located farther than the illumination reshaping component  303  viewed from the inspection target  200 ). In this embodiment, an optical branching component/optical path switching component  1701  and a wavefront sensor  1702  are disposed in an optical path located after an illumination reshaping component  303  (in other words, in an optical path located nearer than the illumination reshaping component  303  viewed from an inspection target  200 ). In order to reshape linear illumination, the adjustment method disclosed in the first embodiment can be performed while the linear illumination is radiated onto a reference chip  205 . 
         [0088]    According to this embodiment, it becomes possible to observe the state of a wavefront that is just before the actual formation of the linear illumination and to feed back the observed wavefront to driving a deformable mirror, so that narrower linear illumination can be formed. 
       Eighth Embodiment 
       [0089]    An eighth embodiment will be described below. Another variation of the location of the wavefront sensor can be thought of.  FIG. 18  is a diagram for explaining the eighth embodiment. This embodiment includes a reference mirror surface  1802  having a polished mirror surface and a wavefront sensor  1801  disposed in the regular reflection position of the incident angle of illumination light  321  instead of the reference chip, the optical branching component/optical path switching component that have been described in the first embodiment to the seventh embodiment. 
         [0090]    The eighth embodiment will be described more concretely. The reference mirror surface  1802  is polished so as to be able to reflect the illumination light, and it is disposed in an arbitrary position such as on the stage  400  or on the inspection target  200  shown in  FIG. 3 . The wavefront sensor  1801  is disposed in the regular reflection position so that the wavefront sensor  1801  can detect the regular reflection light reflected from the reference mirror surface  1802 , and the wavefront sensor  1801  observes the wavefront of the regular reflection light  1803 . 
       Ninth Embodiment 
       [0091]    A ninth embodiment will be described below. The ninth embodiment is characterized in that it includes an illumination observation system  1901  that detects regular reflection light instead of the above-described illumination observation system  307  that detects scattered light and diffracted light. In the description about this embodiment, parts of this embodiment different from those of other embodiments will mainly be described.  FIG. 19  is a diagram for explaining this embodiment. In this embodiment, the reference mirror surface  1802  described in the eighth embodiment is used. An inspection apparatus according to this embodiment includes an illumination observation system  1901  that detects the regular reflection light  1803  reflected by the reference mirror surface  1802  as an image. The illumination observation system  1901  includes an imaging optical system  1903  such as a lens that focuses the regular reflection light  1803  into an image, and a sensor  1902  that detects the focused reflection light image. In addition, there is a case where the sensor  1902  includes plural pixels. As such a sensor  1902 , the so-called beam profiler can be adopted. The regular reflection light image observed by the illumination observation system  1901  is transmitted to a control component  341 , and is used for reshaping the illuminated shape described in the first embodiment (to put it more concretely, it is used at step  1103 , step  1107 , step  1108 , and the like in  FIG. 11 ). 
       Tenth Embodiment 
       [0092]    A tenth embodiment will be described below. In the inspection of a wafer on which circuit patterns are formed, there is a case where the heights of the circuit patterns formed on the wafer are different from each other.  FIG. 20  is a top view of a wafer on which patterns are formed. In  FIG. 20 , in the case where a pattern  2030  having a certain height and a pattern  2040  having its height lower than that of the pattern  2030  are formed on the wafer, if linear illumination  2020  is irradiated onto both patterns redundantly, it may undesirably happen that the linear illumination  2020  is properly focused on one pattern and it is defocused on the other pattern. This embodiment is achieved with this point in mind, and is characterized in that the wavefront of light entering an optical element that converges the light is changed in accordance with the heights of patterns. 
         [0093]    This embodiment will be described more concretely. 
         [0000]    In the description about this embodiment, parts of this embodiment different from those of other embodiments will be described in particular.  FIG. 21  is a diagram for explaining an inspection apparatus according to this embodiment, and particularly for explaining an illumination system  300  of the inspection apparatus. A database  2110  that stores design information about circuit patterns formed on an inspection target  200  is coupled to a control component  341  that creates data for driving a deformable mirror  309 . In addition, the scanning information of a stage  400  (information showing how long the stage  400  has moved in the x and y directions) is transmitted to the control component  341 . In other words, if the dimensions of the linear illumination is known, the location of the linear illumination on the inspection target  200  can be known from the scanning information of the stage  400 . 
         [0094]    The control component  341  checks the known dimensions of the linear illumination, the design information from the design information database  2110 , and the scanning information from the stage  400 , and judges how much part of the linear illumination is irradiated onto each circuit pattern. Subsequently, the control component  341  drives the deformable mirror  309  in accordance with the height of each pattern. 
         [0095]    In addition, this embodiment will be described more concretely.  FIG. 22  is a diagram for explaining this embodiment more in detail. Further, in  FIG. 22(   a ), components disposed in optical paths between the deformable mirror  309  and an illumination reshaping means  303  are omitted for ease of explanation. In  FIG. 22(   a ), it will be assumed that a pattern  2030  having a high height and a pattern  2040  having its height lower than the height of the pattern  2030  are formed in the y scanning direction on the inspection target  200 . The control component  341  checks the known dimensions of the linear illumination, the design information from the design information database  2110 , and the scanning information from the stage  400 , and judges whether the linear illumination is redundantly irradiated onto both the high pattern  2030  and the low pattern  2040  or not (this judgment can be done either before or during the inspection). In the initial state shown in  FIG. 22(   a ), it will be assumed that the linear illumination is focused on both focal point  2050  and focal point  2200  that are as high as the surface of the low pattern  2040 . If the control component  341  judges that the linear illumination is redundantly irradiated onto both the high pattern  2030  and the low pattern  2040 , the control component  341  drives the deformable mirror  309  so that one illuminated region of the linear illumination that overlaps the high pattern  2030  is focused on a focal point  2060  instead of the focal point  2050 . On the other hand, the control component  341  drives the deformable mirror  309  so that the other illuminated region of the linear illumination that overlaps the low pattern  2040  is focused on the focal point  2200 . With the above function of the control component  341 , two regions with focus positions different from each other are formed in one linear illumination. Scanning in the direction shown by an arrow  2080  is performed with the linear illumination that is focused on the focal point  2060  in the case of the high pattern  2030  and is focused on the focal point  2200  in the case of the low pattern  2040 . 
         [0096]    In addition, in this embodiment, a step  2070  is also taken into consideration. In other words, there may be a case where, if the step  2070  is too small to substantially influence the focusing of the linear illumination, the inspection is continued without changing the above-described change of the wavefront. Further, there may be a case where a circuit pattern having two patterns whose heights are different from each other not only in the y scanning direction, but also in the x scanning direction is formed. In this case, it is all right if the wavefront is changed in accordance with the heights of the patterns in the x scanning direction. In this embodiment, although the design information has been used, it is also all right if the image of the illuminated region actually measured in advance or information obtained by a separately-installed auto-focus system or the like is used instead of using the design information. As described above, this embodiment is characterized, for example, in that it changes the wavefront of light entering an optical element used for converging the light in accordance with the heights of patterns. In other words, this embodiment is characterized in that it includes one illuminated region in which plural illuminated regions each of which has its own focal point are formed. According to this embodiment, even in the case where there are patterns whose heights are different from each other, a highly sensitive inspection can be performed. 
       Eleventh Embodiment 
       [0097]    An eleventh embodiment will be described below. As factors that have undesirable influence on the formation of linear illumination, there are environmental factors in an apparatus, especially environmental factors in an illumination system (such as temperature, air pressure, humidity) other than an aberration that can not be removed for some design reason, and a wavefront aberration owing to the processing accuracies of optical elements themselves that are used for convergence. This embodiment is achieved with this point in mind, and is characterized in that it changes the wavefront of light entering optical elements used for converging the light in accordance with environmental factors in an apparatus, especially environmental factors in an illumination system (such as temperature, air pressure, humidity). 
         [0098]    This embodiment will be described more concretely below.  FIG. 23  is a diagram for explaining this embodiment. This embodiment includes an environmental measurement unit  2101  for measuring environmental factors in an illumination system  300  (for example, at least one of temperature, air pressure, and humidity). Plural environmental measurement units  2101  may be installed in the illumination system  300 . The measurement result of the environmental measurement unit  2101  are transmitted to a control component  341 , and the control component  341  drives a deformable mirror  309  in accordance with this measurement result. In other words, the wavefront  307  of light reflected by the deformable mirror  309  is changed in accordance with the result of the environmental measurement unit  2102 . 
         [0099]    In addition, this embodiment will be concretely explained with reference to the flowchart in  FIG. 24 . Step  1101  to step  1110  of the flowchart in  FIG. 22  are the same as those of the flowchart in  FIG. 11  according to the first embodiment. In this embodiment, environmental factors in the apparatus when the desired shape of linear illumination is obtained is measured by the environmental measurement unit  2101 , and the measurement result is stored in the memory in the control component  341 . After an inspection starts at step  1110 , the environmental measurement unit  2101  periodically transmits a measurement result to the control component  341 . The control component  341  judges whether the measurement result is within the allowable range or not (at step  1112 ), and if the measurement result is within the allowable range, the inspection is continued (at step  1113 ). If the measurement result is not within the allowable range, the control component  341  drives the deformable mirror  309 , and changes the wavefront  307  of the light reflected by the deformable  309 . To explain it more concretely, the control component  341  obtains the relationship between variations of the environmental factors in the apparatus and variations of the wavefront  307  when the desired shape of the linear illumination is obtained, and the control component  341  drives the deformable mirror  309  on the basis of this relationship. According to this embodiment, even in the case where there are variations of the environmental factors in the apparatus, a highly sensitive inspection can be performed. 
         [0100]    Although several embodiments have been described above, the present invention is not limited to these embodiments. In the above-described embodiments, it has been described that the wavefront of light that enters an optical element used for forming linear illumination is adjusted so that the linear illumination is reshaped so as to have a width equal to or narrower than the focused focal region. However, the present invention can be applied to the case where an illumination region other than the linear illumination is formed. In the other words, to obtain the wavefront of incident light used for obtaining a desired illuminated shape or to change the wavefront of the incident light used for obtaining a desired illuminated shape are within the limits of the idea of the present invention. 
         [0101]    In addition, the above-described wavefront sensors and deformable mirrors can be adopted in a detection optic system such as an oblique detection system, and an upward detection system. Further, the present invention can be applied to a surface inspection apparatus that inspects a mirror surface wafer. The present invention can be applied not only to a wafer, but also town inspection apparatus for inspecting various boards, and to an optical apparatus for irradiating light to an object. 
       LIST OF REFERENCE SIGNS 
       [0000]    
       
           100  Oblique Detection System 
           101  Oblique Detection Optical System 
           102 ,  802  One-dimensional Sensor 
           103  Focused Focal Position 
           104  Image Focus Position 
           105 ,  805  Objective Lens 
           106 ,  806  Optical Branching Component 
           107 ,  807  Two-dimensional sensor 
           108  Optical Axis 
           109 ,  809  Imaging Lens 
           120 ,  350  Moving Unit 
           200  Inspection Target, 
           201 ,  801 ,  898  Scattered Light 
           202  Focused Focal Region 
           203  Defocused Region 
           204  Normal Line 
           205  Reference Chip 
           300 ,  310 ,  320  Illumination System 
           301 ,  308 ,  311 ,  321  Illumination Light 
           303  Illumination Reshaping Component 
           305  Wavefront Sensor 
           306  Incident Wavefront 
           307  Reflection Wavefront 
           309  Deformable Mirror 
           312 ,  314 ,  322 ,  601 ,  3091  Reflection Component 
           313  Optical Branching Component/Optical Path Switching Component 
           323 ,  331  Optical Path Branching Component/Switching Component 
           341  Control Component 
           342  Driving Component 
           360  Diffraction Light or Scattered Light 
           370  Illumination Observation System 
           400  Stage 
           700  Calculation Processing System 
           701  Display Device 
           800  Upward Detection System 
           901  Illuminated Shape 
           902  Light Source Model 
           903  Theoretical Model of Illumination Shaping Component 
           904  Theoretical Model of Wavefront 
           1000  Defect Inspection Apparatus 
           3092  Actuator 
           3093  Electrostatic Actuator