JP5331673B2 - Inspection method and inspection apparatus - Google Patents

Description

  The present invention relates to an inspection apparatus, an inspection method, and a program used therefor, and for example, relates to a surface inspection apparatus that detects minute foreign matters and defects on a semiconductor wafer.

  In a production line for semiconductor substrates, thin film substrates, etc., in order to maintain and improve product yields, inspection of defects existing on the surface of semiconductor substrates, thin film substrates, etc. is performed. In such a surface inspection apparatus, there is a technique for collecting and irradiating illumination light on a sample surface and detecting light scattered by surface roughness and defects. In order to divide the detection range spatially, there is a technique such as Japanese Patent Laid-Open No. 2005-3447 using a plurality of pixel sensors.

JP 2005-3447 A

  If a multi-pixel sensor is used in the surface inspection apparatus, the range of the detection range can be divided, which is effective for increasing the sensitivity. However, when using a multi-pixel sensor, if the height of the surface to be inspected fluctuates, there is a problem of detecting a location that is not in a range that should be originally detected due to the positional deviation of the illumination spot and the focal deviation of the detection optical system, There is a problem that accuracy decreases.

  The first feature of the present invention is that it has an optical system capable of detecting the height of a sample, and based on the result, inspection is performed while adjusting the position of the sample surface, deterioration of the positional accuracy of defects, illumination / detection optics It has a function to prevent the system from being out of focus.

  The second feature of the present invention is that it has a sample receiving mechanism for stabilizing the height of the sample in a stage having a width large enough to adsorb the entire surface of the sample.

  A third feature of the present invention includes a transport system that moves a sample, an irradiation optical system that irradiates the sample with linear illumination light, a height detection system that measures the height of the sample, and a plurality of pixels. A detection optical system including a detector; a processing unit that inspects a foreign matter or a defect of the sample using a detection result of the detection optical system; and a control unit that controls the height of the sample. Is to control the height of the sample using the measurement result of the height detection system so that the fluctuation amount of the linear illumination light is smaller than the size of the pixel.

  According to a fourth aspect of the present invention, the transport system rotates, and the height detection system detects the height of the position of the front circumference of the position where the irradiation optical system irradiates the linear illumination light. is there.

  A fifth feature of the present invention is that the control unit corrects the variation amount at a time interval in which the variation amount is smaller than the size of the pixel.

  A sixth feature of the present invention is that the transport system has a ball screw mechanism that changes the height of the sample.

  A seventh feature of the present invention is that the transport system has a back surface non-contact type stage.

  An eighth feature of the present invention resides in that the transport system has a back surface adsorption type stage, and the back surface adsorption type stage has the sample receiving mechanism disposed on the outer periphery of the back surface adsorption type stage. .

  A ninth feature of the present invention is that the sample receiving mechanism moves up and down.

  According to one aspect of the present invention, in a surface inspection apparatus having a plurality of pixel sensors, the sample surface position can always be corrected to the focus position of the illumination / detection optical system, high-sensitivity inspection can be performed, and Defect position accuracy can be maintained.

It is the schematic of the surface inspection apparatus which concerns on one Example of this invention. It is an example of the detector position which concerns on one Example of this invention. It is the schematic of the 2nd example of the detection optical system which concerns on one Example of this invention. It is a detection part circuit schematic diagram concerning one example of the present invention. It is a figure which shows the 1st example of the test | inspection range and sample surface position which concern on one Example of this invention. It is a figure which shows the 2nd example of the test | inspection range and sample surface position which concern on one Example of this invention. It is a figure which shows the test | inspection range and height measurement position on the sample surface which concern on one Example of this invention. It is a flowchart figure of the inspection process which concerns on one Example of this invention. It is a figure which shows the mechanism part for height control which concerns on one Example of this invention. It is the schematic of the surface inspection apparatus which concerns on the 2nd example of this invention. It is a figure which shows the sample delivery method of a prior art. It is a figure which shows the wafer delivery method which concerns on the 2nd example of this invention. It is the schematic of the surface inspection apparatus which concerns on the 3rd example of this invention. It is the schematic of the detection optical system which concerns on the 3rd example of this invention. It is a figure which shows an example of the sensitivity adjustment method of the multi-anode photomultiplier tube which concerns on the 3rd example of this invention. It is a figure which shows the 2nd example of the sensitivity adjustment method of the multi anode photomultiplier tube which concerns on the 3rd example of this invention. It is a figure which shows the applied voltage dependence for every channel of the multi anode photomultiplier tube which concerns on the 3rd example of this invention. It is a figure which shows the applied voltage dependence of the multi-anode photomultiplier tube which concerns on the 3rd example of this invention. It is a figure which shows the time-dependent change of the sensitivity of the multi anode photomultiplier tube which concerns on the 3rd example of this invention.

  Embodiments of the invention will be described below with reference to the drawings.

  FIG. 1 is a schematic view of a surface inspection apparatus according to an embodiment of the present invention. As shown in FIG. 1, a back surface non-contact type sample stage 101, a stage driving unit 102, an illumination light source 103, a plurality of pixel sensors 104 for detecting scattered light, a signal processing unit 105, an overall control unit 106, a control unit 107, information display Unit 108, input operation unit 109, storage unit 110, and the like. The stage drive unit 102 includes a rotation drive unit 111 that rotates the back surface non-contact type sample stage 101 around the rotation axis, a vertical drive unit 112 that moves in the vertical direction, and a slide drive unit 113 that moves in the radial direction of the sample. Yes. In order to measure the sample height, a height measurement light source 114 and a height measurement detector 115 are provided separately from the illumination light source 103 for inspection.

  The illumination light source 103 irradiates the sample 100 with illumination light, and the detection optical system 116 collects foreign matter and defects present on or near the sample surface, and light scattered, diffracted, or reflected on the sample surface. Then, an image is formed on the multi-pixel sensor 104 and detected. The illumination light source 103 is a laser, LED, or lamp. When using an LED, color unevenness becomes a problem when light is collected on the sample surface, so it is desirable to pass only a lens in the middle and place a pinhole at the focal position to extract only the part that is less affected by color unevenness. . The back surface non-contact type sample stage 101 supports the sample 100 such as a wafer, and the back surface non-contact type sample stage 101 is moved by the slide drive unit 113 while being rotated by the rotation drive unit 111, so that the relative position is obtained. The illumination light scans the sample 100 in a spiral shape. Therefore, the light scattered by the unevenness of the sample surface is continuously generated, and the scattered light due to the defect is generated in a pulse manner, and shot noise of the light generated continuously becomes a noise component of the surface inspection apparatus. Further, although the present invention has been described using a rotation and translation stage, a two-axis translation stage may be used.

  FIG. 2 is a diagram showing the positional relationship between an illumination spot and a detection optical system according to an embodiment of the present invention. Although one multi-pixel sensor is illustrated in FIG. 1, the number of detectors is not limited as in FIG. 2, and at least one of the azimuth angle Φ and the elevation angle χ from the illumination spot 202 is different. It suffices if the detectors are arranged. In addition, the detection optical system forms a first real image of scattered light on the diffraction grating 303 by the first imaging optical system 301 as shown in FIG. Then, the second imaging optical system 302 may enlarge and form an image on the plurality of pixel sensors 104c.

  FIG. 4 is a schematic diagram of a detector circuit according to an embodiment of the present invention. The generated scattered light is detected by the plurality of pixel sensors 104, and the signal processing unit 105 passes through the BPF (band pass filter 402) and the LPF (low pass filter 405) and separates them into a high frequency component and a low frequency component, respectively. Each signal is corrected by the amplifiers 403 and 406 so as to have the same sensitivity as the other channels, converted into digital signals by the analog / digital converters 404a and 404b, and stored in the storage unit 407 of the computer. When sensor sensitivity variation exists, the signal strength may be corrected using the amplifier 401.

  In surface inspection equipment, the main method for detecting minute foreign matter is to increase the amount of incident light and increase the amount of scattered light generated from the foreign matter, or to increase the inspection time and integrate scattered light. The noise component is reduced by using a multi-pixel sensor as in the invention. When the amount of incident light is increased, there is a problem that the temperature of the sample surface is increased and damage is caused. Therefore, in the present invention, a multi-pixel sensor is used to detect minute foreign matters while maintaining the inspection time. When a multi-pixel sensor is used, the detection range can be spatially divided and measured, so that the light scattered by the unevenness of the sample surface can be reduced, and finer defects can be detected. In the present invention, the multi-pixel sensor 104 includes a multi-anode photomultiplier tube, an avalanche photodiode array, a CCD linear sensor, an EM-CCD (Electron Multiplying CCD), an EB-CCD (Electron Bombardment CCD), an MCP and an optical fiber. An imaging system combining a coupled image intensifier with a CCD or TDI camera.

  FIG. 5 is a diagram showing a detection range and a sample surface position according to an embodiment of the present invention, and is a diagram in which the position of each channel of a plurality of pixel sensors is made to correspond to the sample surface. Illumination light 501 is irradiated onto the sample surface 503. At this time, there may be a change to an ideal position 504 that is shifted by Δz from the sample surface 503 due to a change due to the support method of the sample or undulation of the sample itself during the inspection. In that case, as shown in FIG. 5A, the illumination light is not irradiated to the position to be inspected, and scattered light from a position shifted by Δr is detected. When a single-channel detector such as a photomultiplier tube is used instead of a multi-pixel sensor as in the prior art, the amount of variation Δr with respect to the detection region is sufficiently small so that there is no problem. On the other hand, when the pixel size is reduced using a plurality of pixel sensors as in the present invention, the detection region is shifted by one channel or more, and there is a problem that the position to be detected cannot be detected.

  A correction method when the optical axis of the detector optical system is in the direction perpendicular to the paper surface, that is, at the position of the first detection optical system 203 in FIG. 2 will be described with reference to FIG. 5A and 5B are cross-sectional views in the y-axis direction at the illumination spot. The sample height is adjusted so that the sample surface is always positioned near the sample surface 503. Therefore, in order for the variation amount Δr of the inspection range to be within one pixel, the position accuracy of the stage in the direction perpendicular to the sample stage is:

が必要である。φは照明光の入射角、ｐは試料表面上における複数画素センサ１チャンネルの大きさである。また、試料表面の異物位置精度を向上させるために、ｐ以下の量で径方向に試料を移動させて加算することがある。その場合には、垂直方向のステージの位置精度は径方向の移動量をｐ／ｎ，（ｎ＝１，２，３，４・・・・）とすると

is necessary. φ is the incident angle of the illumination light, and p is the size of the multi-pixel sensor 1 channel on the sample surface. In addition, in order to improve the accuracy of foreign matter position on the sample surface, the sample may be moved in the radial direction by an amount of p or less and added. In that case, if the position accuracy of the vertical stage is p / n, (n = 1, 2, 3, 4,...)

を満たす必要がある。

It is necessary to satisfy.

  Next, the focus shift of the detection optical system will be described. FIG. 5C is a cross-sectional view in the x-axis direction in FIG. 5B, and the illumination light is illuminated from a direction perpendicular to the paper surface. When the sample height fluctuates by Δz, the detection range is shifted by Δw. Therefore, the position accuracy of the stage in the vertical direction is as follows.

かつ

And

を同時に満たさなければならない。

Must be satisfied at the same time.

  On the other hand, a correction method when the optical axis of the detector optical system is obliquely above the paper surface, that is, at the position of the second detection optical system 204 in FIG. 2, will be described with reference to FIG. As shown in FIG. 6, when the position of the sample surface is shifted in the negative z-axis direction, the focal position of the illumination optical system can be considered in the same manner as the first detection optical system 203 described above.

または

Or

を満たす必要がある。一方、検出光学系のピントでずれに関しては、検出領域は、ｙ軸の負の方向及びｘ軸の負の方向にずれる。したがって

It is necessary to satisfy. On the other hand, regarding the focus shift of the detection optical system, the detection region is shifted in the negative y-axis direction and the negative x-axis direction. Therefore

かつ

And

を満たす必要がある。また、この場合も焦点深度をｄ′（＝ｄcosψ）とすると

It is necessary to satisfy. Also in this case, if the focal depth is d ′ (= d cos ψ)

を満たさなければならない。また、散乱光の検出効率を増加させるために、検出光学系のＮＡを大きくかつ短波長化をすると、焦点深度ｄが短くなるため、より試料表面の位置精度が必要となる。

Must be met. Further, if the NA of the detection optical system is increased and the wavelength is shortened in order to increase the detection efficiency of scattered light, the depth of focus d is shortened, so that the positional accuracy of the sample surface is required.

  FIG. 7 is a diagram showing the inspection range and the height measurement position on the sample surface. In this embodiment, an optical laser displacement sensor is used. In FIG. 7A, the light of the height measurement light source 114 is irradiated in the vicinity of the inspection illumination spot 702 for inspecting the sample surface (height measurement illumination spot 701), and the reflected light is heightened. Detection is performed by the measurement detector 115. The height measurement detector 115 uses a light receiving lens, a multi-pixel sensor, a position detection device (PSD), and the like. When the height of the sample surface fluctuates, the position of light incident on the height detector is shifted. In the case of using a multi-pixel sensor, the fluctuation amount is converted from the balance of the signal amount of each channel, and in the position detection element, the photoelectrically converted charge passes through the resistance layer (P layer) and is taken out as current from the electrodes at both ends. Then, the fluctuation amount of the sample surface is converted from the ratio of the current amount. The position of the height measurement illumination spot 701 may be in a range in which the height of the sample surface at the illumination spot position does not change. For example, as shown in FIG. 7, the position may be the front peripheral position of the inspection illumination spot 702.

  FIG. 7B shows the variation of the sample surface height with respect to the rotation angle. The black circle is a point for correcting the sample surface height. As shown in FIG. 7B, height correction must be performed at time intervals that satisfy Equations 1-9 within the measurement points.

  FIG. 8 is a flowchart of a method for inspecting while correcting the height of the sample surface. First, a wafer is set, and the height of the sample surface is measured by the height measuring light source 114. The position of the sample surface is moved to a desired position using the vertical drive unit 112 of the sample stage. While rotating the sample by the rotation driving unit and sliding the sample by the slide driving unit, the sample is irradiated with illumination light to generate scattered light, and the scattered light is detected. On the other hand, the height sensor measures the height in the vicinity of the illumination spot during inspection, and sequentially sends Δz to the vertical drive control unit, and the vertical drive unit sets the sample surface to satisfy Formulas 1 to 4 or Formulas 5 to 9 To control.

  FIG. 9 is a diagram showing a system using a ball screw as an example of a vertical driving method. The ball screw method is inexpensive and easy to handle. A motor unit 905 for rotating the ball screw 904 is fixed to the slide stage 908 on the slide drive unit 907, and a nut 906 of the ball screw 904 is fixed to the rotation drive unit. A laser beam 902 for height measurement is irradiated in the vicinity of the focal spot of illumination light 901 for sample surface inspection. The detector calculates a fluctuation value Δz of the sample surface height, and sends data to the height controller 909. The height control unit 909 converts the motor stepping number necessary for correcting the sample surface position, transfers it to the motor control unit 910, and corrects the height of the sample surface.

  FIG. 10 is a schematic view of a surface inspection apparatus according to the second example of the present invention. In FIG. 10, the sample stage is not the back surface non-contact type sample stage 101 of FIG. In the prior art, the back surface adsorption region fixes a part of the sample back surface, but in the non-adsorption region of the sample 100, the variation amount of the sample surface height is large. Therefore, the entire back surface of the sample is adsorbed by the entire back adsorption type sample stage 121a to fix the sample. In this case as well, the sample surface height can be adjusted by the vertical driving unit 112 and the control unit 107 in the same manner as described above. Compared with a back surface non-contact type stage, since the amount of fluctuation in height is small, there is an effect that the number of times of height correction is small.

  FIG. 11 shows a method of receiving a sample in the conventional back surface adsorption method. The U-shaped transfer arm 122b is used to transfer the sample 100 to the upper side of the conventional backside adsorption type sample stage 121b in the inspection apparatus (FIG. 11A). The U-shaped transfer arm 122b is lowered and the sample 100 is placed on the stage (FIG. 11 (b)). At this time, the U-shaped transfer arm 122b is not in contact with the conventional backside adsorption type sample stage 121b. As it is, only the U-shaped transfer arm 122b is lowered and pulled out (FIG. 11C). In the prior art as shown in FIG. 11, when the conventional backside adsorption type sample stage 121b is changed to the full backside adsorption type sample stage 121a, the U-shaped transfer arm 122b and the conventional backside adsorption type sample stage are used in the conventional sample delivery method. There is a problem that 121a comes into contact.

  FIG. 12 shows a sample receiving method in the entire back surface adsorption method of the present invention. As shown in FIGS. 12A and 12B, the U-shaped transfer arm 122a is used to transfer the sample 100 above the entire back-side adsorption type sample stage 121a in the inspection apparatus. The U-shaped transfer arm 122a is lowered, the sample 100 is placed on the sample support 123 on the stage, and only the U-shaped transfer arm 122a is pulled out. The sample support 123 protrudes through the through hole of the entire back side adsorption type sample stage 121 a, is fixed to the rotation drive unit 111, and can be moved up and down by the motor 124. Thereafter, the sample support 123 is lowered and the sample is placed on the entire back side adsorption type sample stage 121a. At this time, the sample is lowered while drawing air from the vacuum line 126 so that the sample is not displaced.

  FIG. 13 is a schematic view of a surface inspection apparatus according to a third example of the present invention. A case where a multi-anode photomultiplier 131 is used as the multi-pixel sensor will be described. FIG. 14 is a schematic diagram of a detection optical system of the inspection apparatus. Scattered light generated from the illumination spot 141 is collected by the detection lens system 143 and imaged on the photoelectric conversion surface of the photomultiplier tube. As shown in FIG. 14, the multi-anode photomultiplier 131 has a region (hereinafter referred to as an insensitive body) 146 where light cannot be detected between the channels. In order to solve this problem, a microarray lens 144 is arranged in front of the detector, and all scattered light can be detected by the multi-anode photomultiplier 131.

  When using multi-anode photomultiplier tubes, there are differences in sensitivity between channels and individual differences in using multiple multi-anode photomultiplier tubes, which must be corrected. In the present invention, the voltage to be applied to each photomultiplier tube is determined in advance from the average value ratio of the amplification factors of each channel in each multi-anode photomultiplier tube, and individual sensitivity differences among multiple multi-anode photomultiplier tubes are corrected. To do. Furthermore, in order to correct the sensitivity difference between the channels, the output current of each channel is corrected by an amplifier in the electric circuit.

  FIG. 15 shows a sensitivity adjustment unit for investigating applied voltage characteristics of a plurality of multi-anode photomultiplier tubes. As shown in FIG. 15, a multi-anode photomultiplier 131 is irradiated with a certain amount of light by a sensitivity adjustment light source 152 separately from the illumination light for inspection. At this time, the sensitivity adjustment light source is a laser light source, LD, or LED. The wavelength of the light source is preferably close to the wavelength of the illumination light source 103 in the inspection apparatus. The signals photoelectrically converted by the multi-anode photomultiplier 131 are amplified by the amplifiers 154, pass through the analog / digital converter 155, and record the signal amounts of the respective channels in the signal storage unit 156. The multi-anode photomultiplier tube 131 applies a high voltage from an applied voltage power source 157. The amplification factor of the photomultiplier tube is determined by the magnitude of the applied voltage.

  As shown in FIG. 16, the aforementioned sensitivity adjustment unit may be installed in the surface inspection apparatus. Light of the illumination system is closed by a shutter 166, and light is guided from another sensitivity adjustment light source 162 to the multi-anode photomultiplier tube 131 using an optical fiber 164. At this time, light should be irradiated to one channel. Further, the end of the optical fiber 134 is installed on the linear stage 165, and light can be introduced into all the channels by moving it. In addition, the sensitivity adjustment unit is used to correct a change in sensitivity over time at regular intervals.

  A specific method of sensitivity correction will be described. FIG. 17 shows the applied voltage characteristics of signals in each channel of the multi-anode photomultiplier tube. The amplification factor in each channel is different. The average value of the signal with respect to the applied voltage of each channel is calculated, and an average curve is determined as shown in FIG. When a plurality of multi-anode photomultiplier tubes are used in the inspection apparatus, an average curve in each photomultiplier tube is obtained as shown in FIG. Assuming that an applied voltage V is necessary to obtain the output signal I as an ideal value when a certain amount of light is incident, each photomultiplier tube

になるようなＶ₁，Ｖ₂を求める。一般に光電子増倍管のゲインは印加電圧Ｖのｋｎ乗に比例し、ｋは０.７〜０.８の値をとり、ｎは光電子増倍管のダイノードの段数、ａは比例係数である。ダイノードとは光電子増倍管内の増幅用の電極である。また、ｋはダイノードの材質や形状に起因する値である。さらに、Ｖ₁，Ｖ₂は数式１１のように

V ₁ and V ₂ are obtained such that In general, the gain of the photomultiplier tube is proportional to the knth power of the applied voltage V, k takes a value of 0.7 to 0.8, n is the number of dynodes of the photomultiplier tube, and a is a proportional coefficient. A dynode is an electrode for amplification in a photomultiplier tube. K is a value resulting from the material and shape of the dynode. Furthermore, V ₁ and V ₂ are as shown in Equation 11.

補正値Ｐによって高電圧を印加して、感度補正を行う。また、チャンネル間の信号の調整には、電気回路の増幅器１５４でそれぞれ調整する。

Sensitivity correction is performed by applying a high voltage with the correction value P. Further, the signal between channels is adjusted by an amplifier 154 of an electric circuit.

  When a multi-anode photomultiplier tube is used over a long period of time, the amplification factor decreases as shown in FIG. 19 due to deterioration of the dynodes of each channel. Therefore, a signal is obtained by periodically inspecting a sample coated with particles of a known particle diameter, or using the above-described sensitivity correction unit, and changing the value of parameter P to obtain a desired signal amount. To be able to. Further, when this parameter P exceeds a certain threshold value, a warning display process is performed to notify the replacement time of the photomultiplier tube.

  Although this embodiment has been described using a semiconductor wafer as a sample, this inspection method and inspection apparatus are not limited to a wafer as a sample, and can also be applied to inspection of a substrate such as a hard disk.

DESCRIPTION OF SYMBOLS 100 Sample 101 Back surface non-contact type sample stage 102 Stage drive part 103 Illumination light source 104,104a, 104b, 104c Multiple pixel sensor 105 Signal processing part 106 Overall control part 107 Control part 108 Information display part 109 Input operation part 110,407 Storage part DESCRIPTION OF SYMBOLS 111 Rotation drive part 112 Vertical drive part 113,907 Slide drive part 114 Height measurement light source 115 Height measurement detector 116 Detection optical system 121a Whole surface back adsorption type sample stage 121b Conventional system back surface adsorption type sample stage 122a, 122b U Shaped transfer arm 123 Sample support 124 Motor 125 Sample holding support slide ball screw 126 Vacuum line 131 Multi-anode photomultiplier tubes 141, 202 Illumination spot 142 Each channel of multi-anode photomultiplier tube on sample surface 43 Detection lens system 144 Microarray lens 146 Insensitive body 151 Sensitivity adjustment light source 152 Sensitivity adjustment light source 153 Condensing lenses 154, 401, 403, 406 Amplifiers 155, 404a, 404b Analog / digital converter 156 Signal storage unit 157 Application Voltage power supply 161 Sensitivity adjustment light source 162 Sensitivity adjustment light source 163 Condensing lens 164 Optical fiber 165 Linear stage 166 Shutter 201, 501 Illumination light 203 First detection optical system 204 Second detection optical system 301 First imaging optical system 302 Second imaging optical system 303 Diffraction grating 402 Band pass filter 405 Low pass filter 502 Each channel 503 of a plurality of pixel sensors on the sample surface Sample surface 504 Ideal position 505 Detection optical system optical axis 601 Illumination spot ideal position 602 Illumination spot position 603 when the surface position fluctuates Detection region ideal position 604 Detection region ideal position 701 when the sample surface position fluctuates Height measurement illumination spot 702 Inspection illumination spot 901 Illumination light 902 for sample surface inspection High Laser beam 903 for height measurement Detector 904 for height measurement Ball screw 905 Motor unit 906 Nut 908 Slide stage 909 Height control unit 910 Motor control unit

Claims (6)

A transport system for moving the sample;
An irradiation optical system for forming a linear illumination area on the specimen,
A height detection system for measuring the height of the sample;
A detection optical system comprising a detector having a plurality of pixels;
A processing unit for detect foreign objects or defects of the sample with the detection result of the detecting optical system,
A control unit that controls the height of the sample, and the control unit uses a measurement result of the height detection system so that the amount of fluctuation of the linear illumination light is smaller than the size of the pixel. And controlling the height of the sample ,
The transport system rotates,
The height detection system detects the height of the position of the front circumference of the position where the irradiation optical system forms the linear illumination light . The inspection apparatus according to claim 1,
The control unit corrects the variation amount at a time interval in which the variation amount is smaller than the size of the pixel . The inspection apparatus according to claim 1,
The inspection apparatus , wherein the transport system has a ball screw mechanism that changes the height of the sample . The inspection apparatus according to claim 1,
The transport system includes a back surface non-contact type stage . The inspection apparatus according to claim 1,
The transport system has a back surface adsorption type stage,
The back adsorption stage is
An inspection apparatus comprising the sample receiving mechanism disposed on an outer peripheral portion of the back surface adsorption type stage . The inspection apparatus according to claim 6 , wherein
The inspection apparatus characterized in that the sample receiving mechanism moves up and down .

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