Abstract:
In order to enable inspections to be conducted at a sampling rate higher than the pulse oscillation frequency of a pulsed laser beam emitted from a laser light source, without damaging samples, a defect inspection method is disclosed, wherein: a single pulse of a pulsed laser beam emitted from the laser light source is split into a plurality of pulses; a sample is irradiated with this pulse-split pulsed laser beam; scattered light produced by the sample due to the irradiation is focused and detected; and defects on the sample are detected by using information obtained by focusing and detecting the scattered light from the sample. Said defect inspection method is configured such that the splitting a single pulse of the pulsed laser beam into a plurality of pulses is controlled in such a manner that the peak values of the split pulses are substantially uniform.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a defect inspection method of a defect or an extraneous substance of a micro pattern formed on a sample by a thin film process which is represented by a semiconductor manufacturing process or a manufacturing process of a flat panel display and a device using the same. 
       BACKGROUND ART 
       [0002]    An inspection device of a semiconductor device according to a related art has a configuration as disclosed in Patent Literature 1 (Japanese Patent Application Laid-Open No. 2003-130808) and Patent Literature 2 (Japanese Patent Application Laid-Open No. 2007-85958). The inspection device of the semiconductor device disclosed in Patent Literature 1 uses a VUV (vacuum ultraviolet) pulsed laser as a light source. Since pulsed laser light in this range has a low pulse repetition frequency, if the light is used as it is, an inspection speed is lowered. Therefore, Patent Literature 1 discloses a method that splits pulse light which oscillates a laser light source into a plurality of pulses in a delay optical path. 
         [0003]    An inspection device of a semiconductor device disclosed in Patent Literature 2 that uses a UV (ultraviolet) laser for pulse oscillation has a configuration that splits a pulsed laser emitted from a light source so as to be irradiated onto the sample in order to suppress damage to the sample by reducing a peak value of the pulse. 
       CITATION LIST 
     Patent Literature 
       [0000]    
       
         Patent Literature 1: Japanese Patent Application Laid-Open Publication No. 2003-130808 
         Patent Literature 2: Japanese Patent Application Laid-Open Publication No. 2007-85958 
       
     
       SUMMARY OF INVENTION 
     Technical Problem 
       [0006]    In order to improve a sensitivity of detecting a defect on a semiconductor wafer by a scattered light detecting method, it is useful to detect scattered light component from the defect as many as possible. In a Rayleigh scattering region, generally, the scattered light component is inversely proportional to the fourth power of a wavelength and thus it is possible to raise an intensity of the scattered light component from the defect by shortening the wavelength. As a high power and short wavelength light source which is applicable to the inspection, a 248 nm (KrF) excimer laser or a 193 nm (ArF) excimer laser in the DW region and a 157 nm (F2) laser may be used. Such gas lasers have an advantage of a high power. However, a pulse oscillating frequency is approximately several kHz and is triple digits or more slower than a sampling frequency (several MHz or higher) of the scattered light component for the inspection. Therefore, if the scattered light component is sampled so as to correspond to an illumination pulse, the inspection time is delayed. 
         [0007]    As a method that uses the pulsed laser light source in the inspection device, a method that splits a laser emitted from the pulsed laser light source into a plurality of pulses in the middle of the optical path so as to be irradiated onto the sample is disclosed in Patent Literatures 1 and 2. However, an object of Patent Literature 1 and 2 is to reduce a peak value of the pulse. Therefore, Patent Literatures 1 and 2 do not disclose that the sample is inspected at a higher sampling rate than the pulse oscillation frequency of the pulsed laser emitted from the pulsed laser light source. 
         [0008]    Further, in order to make scattered light component from the defect highly sensitive to be proportional to the intensity of the laser light, the intensity of the laser light is increased. However, if a wafer is illuminated by a pulse, damage to the wafer due to instantaneously raised temperature of the wafer caused by the pulse peak value and a wafer damage to the wafer due to an average raised wafer temperature by continuous pulse illumination may occur, which becomes a constraint condition on an increase in the intensity of the laser light. Therefore, it is necessary to perform the inspection while maintaining the illumination intensity so as to be below a critical illumination intensity that accepts the damage caused by the instantaneously raised temperature and the average raised temperature. 
         [0009]    In addition, various defects are present on the wafer and the wafer manufacturing process or the semiconductor device manufacturing process have increased needs to stably detect the various defects. Depending on the size or shape of the defects, the scattering distribution of the defects is variedly changed. Therefore, an optical system needs to have a configuration that is capable of detecting the scattered light component even when the defect scattering distribution is varied. 
         [0010]    An object of the invention is to address the problems of the above-mentioned related art and provide a defect inspection device and a defect inspection method of a semiconductor device which are capable of inspecting a defect without causing damage on a sample at a sampling rate which is higher than a pulse oscillation frequency of a pulsed laser emitted from a pulsed laser light source. 
       Solution to Problem 
       [0011]    In order to achieve the object, the present invention provides a defect inspection method which includes: splitting a single pulse of a pulsed laser beam emitted from a laser light source into a plurality of pulses to form a pulse-split pulsed laser beam; irradiating the pulse-split pulsed laser beam on a sample; focusing and detecting a scattered light generated from the sample by the irradiating of the pulse-split pulsed laser beam; and detecting a defect on the sample using information obtained by focusing and detecting the scattered light generated from the sample. The splitting of the single pulse of the pulsed laser beam into a plurality of pulsed is controlled so as to maintain a peak value of the pulse-split pulsed laser beam to be substantially constant. 
         [0012]    Further, in order to achieve the object, the present invention provides a defect inspection device including: a laser light source that emits a pulsed laser; a pulse splitting unit that splits a single pulse of pulsed laser beam emitted from the laser light source into a plurality of pulses to form a pulse-split pulsed laser beam; an irradiating unit that irradiates the pulsed laser beam which is split by the pulse splitting unit onto a sample; a scattered light detecting unit that focuses a light scattered from the sample onto which the pulse-split pulsed laser beam is irradiated by the irradiating unit to detect the scattered light; and a signal processing unit that detects a defect on the sample using information obtained by focusing and detecting the scattered light from the sample by the scattered light detecting unit. The pulse splitting unit includes a pulse splitting optical path configured to split the single pulse of the pulsed laser beam into a plurality of split pulses and a pulse peak value controller that controls a peak value of the puls-split pulsed laser beam emitted from the pulse splitting optical path so as to be substantially constant. 
       Advantageous Effect of Invention 
       [0013]    According to the present invention, it is possible to inspect a defect at a high speed without substantially lowering a substantial sampling frequency even when a pulse light source having a lower repetition frequency than a sampling frequency of scattered light component is used. Further, by simultaneously illuminating a plurality of viewing fields under the same illumination condition, it is possible to inspect the defect at a high speed. Furthermore, by simultaneously illuminating a plurality of viewing fields under different optical conditions, it is possible to inspect a variety of defects with high sensitivity. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0014]      FIG. 1  is a block diagram schematically illustrating an overall configuration of an inspection device. 
           [0015]      FIG. 2  is a block diagram illustrating a configuration of a pulse splitting optical path. 
           [0016]      FIG. 3  is a view illustrating a polarization state (left side) of pulse light which incidents in the pulse splitting optical path before arriving on an electro-optical element and a polarization state (right side) of pulse light immediately after being emitted from the electro-optical element. 
           [0017]      FIG. 4  is a view illustrating a polarization state (left side) of pulse light which travels around the pulse splitting optical path before arriving again on an electro-optical element and a polarization state (right side) of pulse light immediately after being emitted from the electro-optical element. 
           [0018]      FIG. 5  is a view illustrating a polarization state (left side) of pulse light which travels around the pulse splitting optical path n times before arriving again on an electro-optical element and a polarization state (right side) of pulse light immediately after being emitted from the electro-optical element. 
           [0019]      FIG. 6  is a graph illustrating a concept of change of light intensity when light from a single pulse is split by a pulse splitting method according to the related art. 
           [0020]      FIG. 7  is a graph illustrating a concept of change of light intensity when light from a single pulse is split by a uniform intensity pulse splitting method according to an embodiment of the present invention. 
           [0021]      FIG. 8  is a graph illustrating an output state from a pulse splitting optical path when light from a single pulse is split by a uniform intensity pulse splitting method according to an embodiment of the present invention. 
           [0022]      FIG. 9  is a plan view of a wafer illustrating a state where an optical path of illumination light is bifurcated into three to simultaneously illuminate three locations on the wafer. 
           [0023]      FIG. 10  is a plan view of a wafer and a detection optical system illustrating a schematic configuration in which an optical path of illumination light is bifurcated into three using a mirror to simultaneously illuminate three locations on the wafer and front scattered light component and side scattered light component from the illumination locations are detected by the detection optical systems disposed at four directions. 
           [0024]      FIG. 11  is a plan view schematically illustrating an optical system that bifurcates the optical path of the illumination light into three by a combination of lenses. 
           [0025]      FIG. 12  is a plan view of a wafer and a detection optical system illustrating a schematic configuration in which an optical path of illumination light is bifurcated into three using a mirror and a combination of lenses to simultaneously illuminate three locations on the wafer and a front scattered light component, a side scattered light component, and a back scattered light component from the illumination locations are detected by the detection optical systems disposed at four directions. 
           [0026]      FIG. 13  is a graph illustrating a relationship between an irradiating position of illumination light in a radial direction of a wafer and a temperature of the wafer when the illumination intensity of the illumination light is controlled. 
           [0027]      FIG. 14A  is a graph illustrating a relationship between an illuminating position in a radial direction of a wafer and a rotational velocity of the wafer. 
           [0028]      FIG. 14B  is a graph illustrating a relationship between an illuminating position in a radial direction of a wafer and a transmittance of an attenuator. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
       [0029]    A configuration of a semiconductor wafer defect inspection device according to an embodiment of the present invention will be illustrated in  FIG. 1 . 
         [0030]    The semiconductor wafer defect inspection device includes a stage unit  1100  on which a semiconductor wafer  1  to be inspected is mounted, an illumination optical system  1200  that irradiates illumination light onto the semiconductor wafer  1  to be inspected, a scattered light detection optical system  1300  that detects the scattered light component from the semiconductor wafer  1  onto which the illumination light is irradiated, a signal processing unit  1400  that processes an output signal from the scattered light detection optical system  1300  that detects the scattered light component, and a controller  1500  that controls entire components. 
         [0031]    The stage unit  1100  includes a chuck  2  that supports the semiconductor wafer  1  to be inspected, a rotary stage  3  on which the chuck is mounted, a Z stage  5  which is movable in a height direction, an X stage  6  which is movable in an X-axis direction on a plane, and a Y stage  7  which is movable in a Y-axis direction which is perpendicular to the X-axis direction on the plane. 
         [0032]    The illumination optical system  1200  includes a laser light source  10  that oscillates a pulsed laser, an attenuator  15 , a pulse splitting optical path  20  that splits a pulse of the pulsed laser, a polarizer  25 , and mirrors  30 ,  32 , and  33 . 
         [0033]    The scattered light detection optical system  1300  includes objective lenses  40 ,  45 ,  50 , and  55  that are disposed in a plurality of positions at different elevation angles and azimuth angles and sensors  41 ,  46 ,  51 , and  56  that detect an optical image formed by each of the objective lenses. 
         [0034]    The signal processing unit  1400  includes A/D converters  60 ,  65 ,  70 , and  75  that A/D convert outputs of the sensors  41 ,  46 ,  51 , and  56  and a signal processor  80  that processes a signal converted by each of the A/D converters. 
         [0035]    The controller  1500  includes a mechanical controller  95  that controls a movement of movable mechanisms such as the respective stages of the stage unit  1100  or the attenuator  15 , the pulse splitting optical path  20 , the polarizer  25 , and the mirrors  30  of the illumination optical system  1200  and an operating unit  90 . 
         [0036]    Hereinafter, operations of the units configured as described above will be described. The semiconductor wafer  1  to be inspected is adsorbed on the chuck  2  and the chuck  2  is mounted on the rotary stage  3 , the Z stage  5 , and an X stage  7 . The rotary stage  3  using a spindle is considered and the highest rotational velocity is approximately 1,000 to 100,000 rpm. The wafer  1  is thoroughly inspected by the rotational movement and a linear movement in a horizontal direction by the X stage  7 . Further, it is also possible to thoroughly inspect the wafer by a scanning unit which uses an XYZ orthogonal triaxial stage. 
         [0037]    As the illumination light source for inspection, a laser or a lamp have been used. As the laser light source  10 , a solid laser having a wavelength of 532 nm, 355 nm, or 266 nm, or a gas laser of 248 nm (KrF), a 193 nm (ArF), or a 157 nm (F2) may be used. 
         [0038]    The pulsed laser beam  11  that oscillates the laser  10  transmits the attenuator  15 , the pulse splitting optical path  20 , and the polarizer  25  to incident in the mirror  30  that switches an oblique illumination and a vertical illumination. The light which is reflected from the mirror  30  is reflected from the mirror  32  to obliquely illuminate the wafer  1 . In the meantime, if the mirror  30  is driven by the mechanical controller  95  to be deviated from the optical path, the light is reflected from the mirror  33  to be guided into an optical path that vertically illuminates the wafer  1  and vertically illuminates the wafer  1 . Light scattered from the defect on the wafer  1  by the oblique illumination and the vertical illumination is captured by the objective lenses  40 ,  45 ,  50 , and  55  which are disposed in the plurality of positions at different elevation angles and azimuth angles and detected by the sensors  41 ,  46 ,  51 , and  56  which are disposed on the image planes thoseof. As the sensor, a multi anode photo multiplier or a backside illuminating image sensor (including a CCD or CMOS sensor) may be used. An analog signal output from the sensors  41 ,  46 ,  51 , and  56  that detect the scattered light component from the defect on the wafer  1  is converted into a digital signal by the AD converters  60 ,  65 ,  70 , and  75  and the signal processor  80  determines a defect candidate. A motorized mechanism of the stage or the optical system is controlled by the mechanical controller  95 . The operating unit  90  sets the inspection condition or displays the inspection result in accordance with an operational instruction to the controller or by a user. 
         [0039]    A configuration of the pulse splitting optical path  20  will be illustrated in  FIG. 2 . The pulsed laser beam  11  oscillated from the laser light source  10  incidents in a PBS (polarizing beam splitter)  105  of the pulse splitting optical path  20  by P polarization and then incidents in an electro-optical element  110 . The electro-optical element  110  is, for example, formed of lithium niobate (LiNbO3) and has a characteristic that causes the light that transmits a lithium niobate element in accordance with a voltage which is applied on both sides of the lithium niobate element to be birefringent so that a polarized face  90  of the pulse light which incidents in the electro-optical element  110  is rotated at approximately 90 degrees to be substantially S polarized on the PBS  115 , and some light components are transmitted but most light components are reflected from the PBS  115 . The reflected light is reflected from total reflection mirrors  125  and  130 , incidents in the PBS  105  as S polarization, and is reflected from the PBS  105 . The light which incidents in the electro-optical element  110  at a second cycle has a birefringence which is different from a birefringence of light at a first cycle to rotate the polarized face. In this case, the voltage which is applied to the electro-optical element  110  is controlled so that some light components are transmitted by the PBS  115  and most light is reflected from the PBS  115 . The control of the electro-optical element  110  will be described with reference to  FIGS. 3 ,  4 , and  5 . 
         [0040]      FIG. 3  illustrates a state at the first cycle of the pulse splitting optical path  20  where the pulsed laser beam  11  from the laser light source  10  initially incidents in the electro-optical element  110 . The left side of the arrow illustrates a state of the polarization of the laser beam which incidents in the electro-optical element  110  and the right side of the arrow illustrates a state of the polarization of the laser beam which is emitted from the electro-optical element  110  to incident in the PBS  115 . The laser beam which incidents in the electro-optical element  110  in a state of P polarization is the light controlled by the voltage which is applied to the electro-optical element  110  so as to rotate the polarization plane at approximately 90 degrees. By doing this, an amplitude of the laser beam that transmits the PBS  115  is referred to as A.  FIG. 4  illustrates a state at the second cycle. The laser beam which incidents in the electro-optical element  110  in a state of S polarization is the light controlled by the voltage which is applied to the electro-optical element  110  so that the amplitude of the P polarization laser beam is equal to the transmittance amplitude A at the first cycle. Further,  FIG. 5  illustrates a state at an n-th cycle. As the rotation is repeated, an amplitude of laser beam arriving on the electro-optical element  110  becomes smaller as much as the light is deviated from the PBS  115 . Therefore, in order to maintain the amplitude A of the light that transmits the PBS  115  to be constant, it is required to control the modulation amount of the electro-optical element  110  whenever the rotation is repeated. The modulation amount of the electro-optical element  110  is controlled by the mechanical controller  95 . 
         [0041]      FIG. 6  illustrates a state of a light intensity when the modulation amount of the electro-optical element  110  is fixed. In this case, light intensity is lowered with time. In contrast, by controlling the modulation for every pulse by the electro-optical element  110 , as illustrated in  FIG. 7 , it is possible to split the pulse to have a uniform intensity. If a length of the pulse splitting optical path  20  (for example, a length where light travels around the pulse splitting optical path  20  from an incident surface of the electro-optical element  110  to reach the incident surface of the electro-optical element  110  again) is 60 cm, the modulation for every pulse may be controlled by the electro-optical element  110  at a driving frequency of 500 MHz. 
         [0042]    By increasing the intensity of the illumination light, the scattered light component from the defect is increased in proportion to the intensity. If a noise component for detecting the defect is a roughness of a surface of the wafer, an S/N of defect detection is propositional to 0.5 power of the intensity. The high intensity of the illumination has a trade-off relationship with damage of the wafer or the optical system. Therefore, it is required to increase the intensity while avoiding the damage. 
         [0043]    A method that controls the intensity of illumination in accordance with the scanning speed of wafer  1  is illustrated in  FIG. 13 . The damage of the wafer  1  is an average temperature rising limit A by the laser beam and an instantaneous temperature rising limit B by the peak value of the pulse illumination. The instantaneous temperature rising limit B is higher than the average temperature rising limit A. If the viewing field of the optical system is in an inner circumference of the wafer (a portion close to the center of the wafer), the scanning of the wafer  1  in the viewing field position (laser irradiating location) is slow and thus the temperature of the wafer  1  is easily increased. Therefore, in a position where a linear speed is slow, the illumination intensity is lowered by the attenuator  15  to avoid the damage. As the linear speed is increased, the illumination intensity is correspondingly increased and thus the illumination intensity is constant when the radius is above a radius where the linear speed is constantly controlled. 
         [0044]    In other words, as illustrated in  FIG. 14A , the rotary stage  3  is controlled by the mechanical controller  95  to maximize the rotating speed of the wafer  1  when the inspection is performed from the center of the wafer  1  to the position of a radial direction r0 and to lower the rotating speed of the wafer  1  in accordance with the position of the wafer  1  in the radial direction when the position outside the radial direction r0 is inspected. On the other side, in this case, as illustrated in  FIG. 14B , the attenuator  15  is controlled by the mechanical controller  95  to change a light transmittance of the attenuator  15  so as to become smaller as the position approaches the center of the wafer  1  in accordance with the position of the wafer  1  in the radial direction when the inspection is performed from the center of the wafer  1  to the position of a radial direction r0 and to constantly maintain the light transmittance regardless of the position of the wafer  1  in the radial direction when the position outside the radial direction r0 is inspected. 
         [0045]    As described above, regardless of the radial position of the wafer, the illumination intensity is controlled to be increased to the limit A of the average temperature rise  1330 . In a case that the pulse splitting is not performed, or in a case that the peak value of the split pulse is changed depending on the time similarly to the related art even though the pulse splitting is performed, even if increasing the illumination intensity so that the average temperature rise  1330  is the limit A, the instantaneous temperature rise  1340  may exceed the limit B. In contrast, according to this embodiment, the pulse splitting is performed so that the peak values of the split pulses are substantially constant as illustrated in  FIG. 2  to lower the pulse peak value. Therefore, the pulse peak value may be reduced, and thus the instantaneous temperature rise may be reduced to  1350 . 
       Second Embodiment 
       [0046]    In the first embodiment, a configuration where a pulse of the pulsed laser beam  11  is split to illuminate the wafer  1  has been described. In a second embodiment, a method that splits a laser beam of which a pulse is split into a plurality of optical paths to illuminate the wafer  1  will be described. 
         [0047]    In  FIG. 8 , a state of split pulses is illustrated. It is assumed that a period T2 of the pulse that oscillates the pulsed laser beam is three times of T1 which is a split pulse generation time. Also in this case, an example in which the inspection is performed by a uniform motion is illustrated in  FIG. 9 . The illumination light illuminates three areas  140 ,  145 , and  150  on the wafer  1 . The intervals  155  of the three areas correspond to the split pulse generation time T1. Therefore, three viewing fields are simultaneously illuminated for T1 to detect the scattered light component. When a next pulse is irradiated, scattered light component in an area where the scattered light component has not been detected is detected. 
         [0048]    A configuration of an optical system that simultaneously detects a plurality of viewing fields is illustrated in  FIG. 10 . The illumination light  35  which is reflected from the mirror  32  with the configuration illustrated in  FIG. 1  incidents in the mirror  160 . Here, the mirror  160  has a characteristic that transmits two third of the incident light and reflects one third thereof. The illumination light which is reflected from the mirror  160  goes toward the semiconductor wafer  1 . The light that transmits the mirror  160  having the above-mentioned characteristic incidents in a half mirror  165  that transmits half of the incident light and reflects the remaining light. The illumination light reflected from the half mirror  165  goes toward the semiconductor wafer  1 . The light which transmits the half mirror  165  is reflected by a total reflection mirror  170  to go toward the semiconductor wafer  1 . The illumination light which is reflected (split) by the mirror group  160 ,  165 , and  170  having the above-mentioned characteristic illuminates areas  140 ,  145 , and  150  on the semiconductor wafer  1  with the same illumination intensity. 
         [0049]    Among light scattered from the area  140  which is illuminated by the illumination light  36  reflected from the mirror  160 , light which incidents in the lenses  40 ,  45 ,  50 , and  55  is focused to be detected by the sensors  44 ,  49 ,  52 , and  57 . Among light scattered from the area  145  which is illuminated by the illumination light  37  reflected from the mirror  165 , light which incidents in the lenses  40 ,  45 ,  50 , and  55  is focused to be detected by the sensors  43 ,  48 ,  53 , and  58 . Further, among light scattered from the area  150  which is illuminated by the illumination light  38  reflected from the mirror  170 , light which incidents in the lenses  40 ,  45 ,  50 , and  55  is focused to be detected by the sensors  42 ,  47 ,  54 , and  50 . For example, from the viewpoint of the lens  40 , since the detection viewing fields  140 ,  145 , and  150  are different spaces, images formed by using the lens  40  are also formed in the different positions. Therefore, the sensors  42 ,  43 , and  44  may be disposed in an image plane of each of the viewing fields. Further, the sensors  47 ,  48 ,  49 ,  52 ,  53 ,  54 ,  57 ,  58 , and  59  that individually detect the scattered light component of the viewing field are disposed on the image planes by the lenses  45 ,  50 , and  55 . Therefore, also in the image plane by the lenses  45 ,  50 , and  55  where the sensors  42 ,  43 , and  44  may be disposed on the image plane of each viewing field, sensors  47 ,  48 ,  49 ,  52 ,  53 ,  54 ,  57 ,  58 , and  59  that individually detect the scattered light component of the viewing fields are disposed. 
       Modified Embodiment of Second Embodiment 
       [0050]    In the configuration illustrated in  FIG. 10 , a configuration in which the optical path of the illumination light is split into three using three mirrors  160 ,  165 , and  170  has been described. However, this configuration has a limitation in narrowing the interval of the mirrors. Therefore, the illumination areas  140 ,  145 , and  150  on the wafer  1  may not be closer to each other than the limitation that allows the three mirrors  160 ,  165 , and  170  to be closer. 
         [0051]    In order to address the problems, using a split illumination optical system  1700  which is provided in the light path of the illumination light  35  reflected from the mirror  32 , a configuration of a split illumination optical system  1600  that allows three illumination areas  2140 ,  2145 , and  2150  on the wafer  1  to be closer to each other without broadening a width of light beam is illustrated in  FIG. 11 . The pulsed laser beam  35  which is reflected from the mirror  32  incidents in an intensity uniformizing element  174  that uniformly distributes the intensity in the cross section of the pulsed laser beam. As an example of the uniformizing element  174 , an aspheric lens element or a diffractive optical element may be used. The pulsed laser beam whose intensity distribution in the cross section of the beam is uniformized by the uniformizing element  174  incidents in the lens array  175 . The lens array  175  has a plurality of comparatively small-sized lenses  176  to focus plural lights in each of the focal position of the plurality of comparatively small-sized lenses  176  from one incident beam  35 . The lights focused by the lenses  176 - 1  to  176 - 3  of the lens array  175  are collimated by the lens  180  and focused by the lens  185  in spatially different positions  2140 ,  2145 , and  2150  on the wafer  1 . Therefore, it is possible to focus and illuminate the beams in three viewing fields close to each other. 
       Third Embodiment 
       [0052]    In the configuration of  FIG. 10  which has been described in the second embodiment, only front and side scattered light component is detected. However, depending on the type of the defect, some defects are strongly backwardly scattering the illuminated light. Therefore, in order to broadly detect the defect, a configuration that separately detects the scattered light component in the front, side, and backside is desirable. As compared with the configuration illustrated in  FIG. 10 , as a configuration that detects light which is scattered in the front, side, and backside by switching the direction of the illumination light, a configuration having a plurality of illuminations and detecting a plurality of viewing fields is illustrated in  FIG. 12 . 
         [0053]    With the configuration illustrated in  FIG. 1 , the illumination light (pulsed laser beam)  35  reflected from the mirror  32  incidents in the mirror  300 . Here, the mirror  300  has a characteristic that transmits two third of the incident light and reflects one third thereof. The illumination light reflected from the mirror  300  is focused by the lens  315  to illuminate an area  3140  on the wafer  1 . Among the illumination light that transmits the mirror  300 , half of an amount of the light which incidents in the half mirror  305  is transmitted and the remaining is reflected. The light reflected from the half mirror  305  is focused by the lens  320  to illuminate the area  3145  on the wafer  1 . The light that transmits the half mirror  305  is reflected by the total reflection mirror  310  and focused by the lens  325  to illuminate the area  3150  on the wafer  1 . 
         [0054]    As described above, the directions of the light which illuminates the areas  3140 ,  3145 , and  3150  on the wafer  1  are different from each other. From the viewpoint of the area  3140 , the lens  340  focuses the back scattered light component, the lens  345  focuses the side scattered light component, and the lenses  350  and  355  focus the front scattered light component to be detected by the detectors  342  to  344 ,  347  to  349 ,  352  to  354 , and  357  to  359 . Further, from the viewpoint of the area  3145 , the lenses  340  and  355  detect the side scattered light component and the lenses  345  and  350  detect the front scattered light component. Furthermore, from the viewpoint of the area  3150 , the lenses  340  and  345  detect the front scattered light component, the lens  350  detects the side scattered light component, and the lens  355  detects the back scattered light component. With this configuration, the scattered light component in all directions may be detected, which may efficiently improve a defect capturing rate. 
         [0055]    The configuration, the function, and the image processing contents described in the embodiments may be considered to be combined in various ways. However, it is obvious that the combination thereof falls into the scope of the present invention. 
       INDUSTRIAL APPLICABILITY 
       [0056]    The present invention may be applied to a device that inspects a defect such as a defect or an extraneous substance of a micro pattern formed on a sample by a thin film process which is represented by a semiconductor manufacturing process or a manufacturing process of a flat panel display. 
       REFERENCE SIGNS LIST 
       [0000]    
       
         
           
               1  Wafer 
               3  θ stage 
               5  Z stage 
               7  X stage 
               10  Laser light source 
               15  Attenuator 
               20  Pulse splitting optical path 
               25  Polarizer 
               40 ,  45 ,  50 ,  55  Objective lens 
               41 ,  46 ,  51 ,  56  Sensor 
               80  Signal processor 
               90  Operation unit 
               95  Mechanical controller 
               105 ,  115  PBS 
               110  Electro-optical element 
               1125 ,  130  Mirror 
               174  Intensity uniformizing element in the beam 
               175  Lens array