JP5608722B2 - Inspection device and method for adjusting inspection device - Google Patents

Description

  The present invention relates to a surface inspection apparatus for inspecting minute foreign matters, scratches, dirt, etc. (hereinafter collectively referred to as defects) present on the surface of an object to be inspected such as a semiconductor substrate (semiconductor wafer).

  In a production line for semiconductor substrates, thin film substrates, and the like, surface defects such as semiconductor substrates and thin film substrates are inspected in order to monitor the dust generation status of the production apparatus.

  Conventionally, as a technique for detecting a minute defect on the surface of an object to be inspected such as a semiconductor substrate, for example, as described in US Pat. No. 5,798,829 (publication), a focused laser is used. When the surface of the semiconductor substrate is irradiated with a fixed beam (the illuminated laser beam is formed on the surface of the semiconductor substrate, the illuminated area is called an illumination spot), and there is a defect on the semiconductor substrate. Some of them detect the scattered light from the generated defects with a photodetector and inspect the defects on the entire surface of the semiconductor substrate.

  In such a surface inspection apparatus, generally, the signal intensity obtained from the photodetector is converted into a detected defect size to obtain an inspection result. This conversion is performed by measuring a calibration wafer coated with standard particles (generally PSL: polystyrene latex spheres) whose particle size is known in advance before inspection, and generating the known standard particle size particles. The relationship between the scattered light intensity and the corresponding signal intensity obtained from the photodetector is calculated as a calibration curve, and the signal intensity obtained from the photodetector is calibrated at the time of inspection of the actual wafer to be inspected. It is performed by applying to a curve and converting to a particle size equivalent to a standard particle. Such a calibration method is described in, for example, Japanese Patent Application Laid-Open No. 2003-185588.

JP 2003-185588 A

  In the surface inspection apparatus, it is possible to inspect smaller defects by using PSL having a smaller particle diameter. However, the particle size of PSL is finite.

  Therefore, in the conventional surface inspection apparatus, no consideration is given to how to inspect defects having a particle size that is too small to be set in the PSL that will be required in the semiconductor manufacturing process inspection in the near future. It was.

  The present invention includes a light source device that generates light simulating at least one of wavelength, light amount, temporal change in light amount, and polarization of light scattered, diffracted, or reflected by an object to be inspected, One feature is that the light is incident on a photodetector of the surface inspection apparatus.

  According to the present invention, the light extracted from the light source device is summed at least with the approximate DC component and the approximate pulse component, and the magnitude of the approximate DC component, the magnitude of the approximate pulse component, and the width of the approximate pulse component Another feature is that at least one can be changed in an arbitrary range and resolution.

  Another feature of the present invention is that a light amount monitor detector that receives a part of light emitted from the light source is provided, and the drive power supply can be controlled using an output signal of the light amount monitor detector. .

  Another feature of the present invention is that it includes a light-attenuating unit that attenuates light emitted from the light source, and can be extracted after the light is reduced.

  Another feature of the present invention is that the light source device includes at least one optical fiber and extracts the light from the optical fiber.

  Another feature of the present invention is that the intensity ratio of light extracted from the plurality of optical fibers can be arbitrarily changed.

  Another feature of the present invention is that a surface inspection apparatus includes the light source device.

  The present invention uses the light source device to measure the relationship between the incident light of the photodetector and the output signal intensity, to store the relationship in the surface inspection device, and to store the relationship when the particle size calculation unit calculates the particle size. Another feature is to reflect the information.

  Another feature of the present invention is that the particle size calculator uses the light source device to create a calibration curve for converting the output signal of the photodetector into the particle size of the defect.

  The present invention incorporates a plurality of light source devices inside a surface inspection apparatus, associates the plurality of optical fibers with a plurality of photodetectors, and arranges output ends of the plurality of optical fibers in the vicinity of the plurality of photodetectors. Another feature is to do.

  According to the present invention, a finer defect can be inspected.

FIG. 3 is a diagram illustrating a configuration of a light source device for generating a reference light amount according to the first embodiment. FIG. 4 is a diagram showing a time-varying waveform of light output obtained from the light source device for generating a reference light quantity according to the first embodiment. 1 is a diagram illustrating a configuration of a surface inspection apparatus according to a first embodiment. FIG. 3 is a diagram illustrating an arrangement of photodetectors in the surface inspection apparatus according to the first embodiment. FIG. 2 is a diagram illustrating a configuration of a light source device for generating a reference light quantity built in the surface inspection apparatus according to the first embodiment. FIG. 3 is a diagram for explaining a method of introducing output light of a light source device for generating a reference light quantity to each photodetector of the surface inspection apparatus according to the first embodiment. The flowchart which shows the flow of the conventional calibration curve creation process. 5 is a flowchart showing a flow of creating a reference light amount database in the first embodiment. 5 is a flowchart showing a flow of creating a reference light amount database in the first embodiment. 5 is a flowchart showing a flow of processing for adding data corresponding to a particle size not in the particle size series of standard particles in the first embodiment. 3 is a flowchart showing the flow of calibration curve creation processing according to the first embodiment. 3 is a flowchart showing the flow of calibration curve creation processing according to the first embodiment. 6 is a table showing input parameters in the GUI when creating a calibration curve in the first embodiment. An example in which light from a light source device for generating a reference light quantity is incident on a one-dimensional CCD using an arrayed optical fiber.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  A first embodiment of the light source device of the present invention is shown in FIG. It is desirable to use a small light source with a narrow wavelength band, such as a light emitting diode, a semiconductor laser, or a semiconductor laser pumped solid-state laser, as the light emitting element 1 as a light source. The emission wavelength of the light emitting element 1 is approximately equal to the wavelength of illumination light used by a surface inspection apparatus to be simulated, which will be described later, the emission wavelength band of the light emitting element 1 includes the wavelength of the illumination light, or It is desirable that the spectral sensitivity characteristics of the photodetector used by the surface inspection apparatus be selected so that the wavelength of the illumination light and the emission wavelength of the light emitting element 1 are approximately equal. In this embodiment, a case where the wavelength of illumination light of a surface inspection apparatus to be simulated, which will be described later, is 355 nm will be described. Therefore, an ultraviolet light-emitting diode having a center wavelength of 365 nm is used as the light-emitting element 1.

  After the direct current from the direct current generator 2 is amplified by the direct current amplifier 21 and the pulse current from the pulse current generator 3 is amplified by the pulse current amplifier 31, both are led to the current adder 4. These are added and supplied to the light emitting element 1 as a drive current. A DC current set value input unit 6 is attached to the DC current generator 2, and an operator can input the amount of DC drive current to be given to the light emitting element 1 from here. The pulse current generator 3 is provided with a pulse current set value input unit 7, a pulse width input unit 8, and a pulse repetition interval input unit 9, from which the operator can determine the amount of pulse drive current to be applied to the light emitting element 1. The pulse width and repetition interval time can be input. At this time, the temporal change in the emission intensity of the light emitting element 1 has a waveform as shown in FIG. Light emitted from the light emitting element 1 is collected by the condenser lens 10 and enters the incident side end face of the optical fiber 20.

  However, when deterioration of the applied current vs. output characteristics of the light emitting element 1 over time occurs while the values of the DC driving current and the pulse driving current applied to the light emitting element 1 are kept constant, the light source device The amount of light extracted from the optical fiber 20 varies.

  In order to avoid such fluctuations, in this light source device, a beam splitter 11 is disposed between the condensing lens and the incident side end face of the optical fiber 20, and a part of the light emitted from the light emitting element 1 is transferred to the beam splitter 11. And branch to the light amount monitor detector 14. The light quantity monitor detector 14 is a silicon photodiode, and generates an output signal proportional to the incident light quantity. This output signal is fed back to the DC current amplifier 21 and the pulse current amplifier 31 to finely adjust the respective amplification factors. That is, when the output signal of the light amount monitoring detector 14 decreases under the condition that the set values to the DC current set value input unit 6 and the pulse current set value input unit 7 are constant, the DC current amplifier 21 Further, the gain of the pulse current amplifier 31 is finely adjusted to increase, and the intensity of the output signal of the light amount monitor detector 14 is kept constant. By this feedback control, even when the light emitting element 1 is deteriorated with time, the influence can be suppressed and the light quantity extracted from the optical fiber 20 by the light source device can be stabilized so as not to fluctuate.

  Further, an ND filter 12 is installed between the condenser lens and the incident end face of the optical fiber 20. The ND filter 12 can be inserted into or removed from the optical path by the switching mechanism 13. The amount of light incident on the optical fiber 20 can be reduced by reducing the drive current of the light emitting element 1, but there is a limit to the lower limit of the drive current that can reduce the amount of light with stable and good linearity. Therefore, when it is desired to reduce the amount of light incident on the optical fiber 20 beyond this range, the ND filter 12 is inserted into the optical path, and the dimming action by the ND filter 12 and the dimming action by the drive current are used in combination. Can do.

Here, typical specifications of light to be measured detected by a built-in photodetector in a general surface inspection apparatus will be described. The structure of a general surface inspection apparatus is, for example, as described in FIG. 6 of Japanese Patent Application Laid-Open No. 2008-020271. In an example of a standard inspection condition of such a surface inspection apparatus, the rotary stage is rotated at 4000 rotations / minute. Further, the diameter of the illumination spot in the radial direction of the semiconductor wafer (the illuminance is defined by an outline where e: the illuminance at the center of the illumination spot decreases to 1 / square of the base of the natural logarithm) is 10 micrometers. . Therefore, when foreign matter is attached to a position of a radius of 75 mm on the wafer to be inspected (here, the size of the foreign matter is sufficiently smaller than 1 micrometer), the foreign matter is 10 with the rotation of the rotary stage. The time for passing through the illumination spot having a micrometer diameter is 10 / {2 × π × 75 × 1000 × (2000/60)} = 3.18 × 10 ⁻⁷ (seconds), which is 318 nanoseconds. Produces a pulsed emission having a pulse width of 318 nanoseconds.

  In the light source device of the present embodiment, pulse emission having equivalent time characteristics can be generated by matching the set value in the pulse width input unit. In addition, the intensity of pulsed light emission due to defects depends on the material and particle size of the defect, but in a region where the particle size of the defect is sufficiently smaller than the wavelength of the illumination light, a scattered light of a type called Rayleigh scattering is generated. A scattered light having a mode called Mie scattering is generated up to a particle size of a size larger than the wavelength. In the Rayleigh scattering region, since the scattered light intensity is proportional to the sixth power of the particle size, a small particle size difference appears as a large scattered light amount difference. For example, if the small target is 20 nanometer particles and the larger particle is 80 nanometers, the range of light quantity is about 1000 times the dynamic range. As described above, in the light source device of this embodiment, the amount of light emitted from the light emitting element 1 can be adjusted by the combination of both the ND filter and the drive current. Therefore, when the amount of light is adjusted only by the magnitude of the drive current. In comparison, the light source device can deal with the amount of light changing in such a large dynamic range without causing the light emission amount to become unstable.

  Furthermore, in the surface inspection apparatus, even when such a defect does not pass through the illumination spot, scattered light (hereinafter referred to as background scattered light) is generated in the illumination spot due to the minute surface roughness (micro roughness) of the wafer to be inspected. It always occurs. In general, in the case of a semiconductor wafer having a good polishing finish, such surface roughness is almost uniform everywhere in the semiconductor wafer surface. Therefore, the temporal change in the intensity of the background scattered light is substantially a direct current component. However, the absolute value of the strength varies depending on the surface finish state. In the light source device of this embodiment, the input value to the direct current set value input unit 6 is changed to individually adjust the background scattered light having different intensities due to the different surface roughness. It is possible. As described above, in the light source device of this embodiment, (1) a set value to the DC current set value input unit 6, (2) a switch between the set value to the pulse current set value input unit 7 and the ND filter 12, (3) By combining the set value to the pulse width input unit 8, it is possible to generate light equivalent to the light to be measured that enters the photodetector when one defect passes through the illumination spot in an actual surface inspection apparatus. It becomes possible. Further, in this light source device, (4) by setting a repetition cycle time to the set value of the pulse repetition interval input unit 9, it is possible to repeatedly generate a single light emission phenomenon generated from one defect at a constant time interval. it can.

  The light source device of the present embodiment can be used as a reference light amount generation device that is built in the surface inspection device and generates a constant amount of light.

  FIG. 3 shows a configuration diagram of the surface inspection apparatus in which the light source device of this embodiment is incorporated. The surface inspection apparatus in FIG. 3 is obtained by incorporating the light source device of the present invention into the surface inspection apparatus described in FIG. 6 of Japanese Patent Application Laid-Open No. 2008-020271 and adding the control function of the light source device. Detailed explanations other than the light source device and its control part are omitted.

In the surface inspection apparatus, a plurality of photodetectors are provided to individually capture the three-dimensional angular distribution of scattered light generated from defects on the surface of the object to be inspected, that is, the components of scattered light traveling to different azimuths and elevation angles. As shown in the bird's-eye view of FIG. 4, the surface inspection apparatus according to the present embodiment includes ten photodetectors 50 each including a photomultiplier tube. Therefore, in the present embodiment, ten reference light source generating light source devices 100 according to the present invention are built in the surface inspection apparatus in correspondence with the number of the photodetectors 50. Each of the reference light quantity generating light source devices 100 is the same as that described in the first embodiment except for the following points, and only the different parts will be described in detail.
(B) As shown in FIG. 5, instead of the DC current set value input unit 6, the pulse current set value input unit 7, the pulse width input unit 8, and the pulse repetition interval input unit 9, a DC current setting interface 61, a pulse current setting interface 71, a pulse width setting interface 81, and a pulse generation timing signal interface 91 are respectively attached to the control microcomputer 40 built in the surface inspection apparatus, and from the control microcomputer 40 The amount of DC drive current applied to the light emitting element 1, the amount and pulse width of the pulse drive current, and the generation timing of the pulse drive current can be controlled by the command.
(B) The switching mechanism 13 inserts or removes the ND filter 12 into or from the optical path according to a command from the control microcomputer 40.
(C) As shown in the side view of FIG. 6, the output-side end face of the optical fiber 20 is actually near the light-receiving face of the single photodetector 50 associated with each reference light amount generation light source device 100. The light detector 50 does not interfere with the detection of scattered light generated from defects on the semiconductor wafer when inspecting the wafer to be inspected, and the light extracted from the output side end face of the optical fiber 20 is effectively used. It arrange | positions so that it may contact the light-receiving surface of the photodetector 50. FIG.

Heretofore, a calibration curve for converting an output signal from a photodetector into a particle size of a defect at the time of inspection has been created by performing the following work in advance before actual inspection. FIG. 7 is a flowchart showing the flow of conventional calibration curve creation processing.
Step 1: An operator has a surface condition (film formation, surface roughness, etc.) equivalent to that of a semiconductor wafer to be inspected before starting the inspection, and a standard particle (generally PSL is generally known) on a clean semiconductor wafer. Prepare a calibration wafer coated with polystyrene latex spheres). Usually, a wafer coated with standard particles having several different particle sizes within a particle size range that needs to be detected at the time of inspection is used.
Step 2: The operator sets the inspection conditions of the surface inspection apparatus of the present embodiment in accordance with the inspection conditions for the inspection to be performed on the actual wafer to be inspected.
Step 3: The operator starts inspection of the calibration wafer.
Step 4: The surface inspection apparatus inspects and records the relationship between the size of each standard particle applied on the calibration wafer and the signal intensity obtained from the photodetector corresponding to the standard particle. To do.
Step 5: After the inspection in Step 4 is completed, the surface inspection apparatus performs statistics based on the relationship between the size of each standard particle recorded in Step 4 and the signal intensity obtained from the photodetector corresponding to the standard particle. Calculate and create a calibration curve.

  The surface inspection apparatus according to this embodiment has a function of creating a calibration curve using the built-in reference light amount generation light source device 100 in addition to the function of creating a calibration curve using a conventional calibration wafer. This function makes it possible to create a calibration curve without using a calibration wafer, so that such inconvenience can be solved. This function and its operation are detailed below.

  The surface inspection apparatus according to the present embodiment includes calibration curve creation software, which stores storage areas for a reference light intensity database, calibration wafer data, a standard particle data table, a standard particle counter, and a calibration curve creation data table. I have.

  First, the surface inspection apparatus according to the present embodiment performs the following process to create a reference light quantity database that stores parameter values necessary for causing the reference light quantity generation light source device to generate a desired light quantity. FIG. 8 is a flowchart showing a flow of creating the reference light quantity database.

Prior to the following processing, the operator has a surface condition (film formation, surface roughness, etc.) equivalent to that of the semiconductor wafer to be inspected, and is on a circumference of a predetermined radius (for example, 75 mm) on a clean semiconductor wafer. A calibration wafer coated with standard particles (generally using PSL: polystyrene latex spheres) having a particle size for which data should be registered in the reference light quantity database is prepared, and the inspection conditions of the surface inspection apparatus of this embodiment (the calibration wafer) (Including the diameter and illuminance of the illumination spot that illuminates) is set in accordance with the inspection conditions of the inspection to be performed on the actual wafer to be inspected, and then the inspection of the calibration wafer is started.
Step 1: Receives the “particle size value of the applied standard particles” input by the operator. Step 2: Only the light generated from the calibration wafer by the light from the inspection light source is received by each of the ten light detectors 50, and the output of the light source device 100 for generating the ten reference light amounts is output. The light is prevented from entering each of the photodetectors 50.
Step 3: An inspection is performed, and the signal intensity obtained for each of the photodetectors 50 corresponding to the standard particles applied on the calibration wafer is individually recorded. Among the signals obtained from each photodetector, the signal intensity corresponds to the signal intensity corresponding to the background scattered light whose temporal change is approximately a direct current component and the scattered light from standard particles whose temporal change is pulsed. Record both corresponding signal strengths.
Step 4: Next, each of the photodetectors 50 receives only the output light of each of the reference light amount generation light source devices 100, and the light generated from the calibration wafer by the light from the inspection light source. Is not incident on the photodetector 50.
Step 5: The pulse width setting of the light source device 100 for generating the reference light amount is determined from the radius of the position where the standard particles are applied, the rotational speed of the rotary stage used in the inspection of Step 3, and the diameter of the illumination spot by the following formula: Set to the calculated time.

Illumination spot diameter / (2 x π x radius x rotation speed)
Step 6: Predetermined initial values are given to the DC current setting and the pulse current setting of the ten reference light amount generation light source devices 100, respectively. At this time, a light output of a direct current component corresponding to each direct current set value is continuously generated from each reference light amount generation light source device 100.
Step 7: A pulse generation timing signal is given to the reference light amount generation light source device 100. As a result, in addition to the continuous DC component, a pulse component is superimposed on the output light from the light source device 100 for generating the reference light quantity, so that it is obtained from each photodetector 50 corresponding to this output light. Individually record the signal strength. At this time, as in Step 3, both the signal intensity corresponding to the DC component and the signal intensity corresponding to the pulse component are recorded.
Step 8: Until each signal intensity recorded in Step 7 becomes equal to each signal intensity recorded in Step 3, the DC current setting value and the pulse current setting value of each of the ten reference light quantity generation light source devices are changed. Adjust and repeat Step 7.
Step 9: Each DC current value finally determined in Step 8 is registered at a location corresponding to each photodetector 50 in the reference light quantity database.
Step 10: The particle size value received in Step 1 and each pulse current value finally determined in Step 8 are paired and registered in a location corresponding to each photodetector 50 in the reference light amount database.

  When there are a plurality of particle diameters whose data should be registered in the reference light quantity database, the above operation may be repeated from the calibration wafer preparation as many times as necessary.

As for the particle size of a value not in the particle size series of the standard particle, each pulse current value In corresponding to the amount of scattered light that the standard particle will generate when it is assumed that the standard particle of the particle size exists. (D) can be calculated by the following procedure and added to the reference light quantity database. FIG. 9 is a flowchart showing a flow of processing for adding data corresponding to a particle size not in the particle size series of the standard particles.
Step 1: Let d be the particle size of standard particles to be added to the reference light quantity database.
Step 2: In order to accurately obtain In (d), the particle diameter closest to d among the particle diameters stored in the reference light quantity database is defined as d ', and the n-th particle corresponding to the standard particle. The pulse current value corresponding to the first photodetector (n = 1, 2,..., 10) is assumed to be In (d ′).
Step 3: When d is smaller than approximately 1/6 of the wavelength used at the time of inspection, a Rayleigh scattering region is obtained. In the Rayleigh scattering region, the amount of light scattered by the defect is proportional to about the sixth power of the particle size of the defect. The pulse current value In (d) is obtained.

In (d) = In (d ′) × (d / d ′) ⁶ Step 4: When d is larger than the criterion of Step 3, it becomes a Mie scattering region. Each pulse current value In (d) corresponding to the amount of scattered light that will generate standard particles is obtained.
Step 5: A simulation calculation based on the Mie scattering theory is performed, and the amount of scattered light Sn () in which a standard particle having a particle diameter d is generated in a small solid angle range that is collected and detected by the nth photodetector. d) and the amount of scattered light Sn (d ') that will generate standard particles of particle size d' are obtained. It should be noted that all the conditions other than the particle diameter are assumed to be equivalent when calculating both. Step 6: Each pulse current value In (d) is obtained by the following equation.

In (d) = In (d ′) × (Sn (d) / Sn (d ′))
Alternatively, if the transmission efficiency ηn of each condensing optical system in the optical path from the illumination spot on the wafer to be inspected to each photodetector is known in advance, the amount of light obtained by multiplying the Sn (d) by ηn That is, ηn × Sn (d) may be taken as In (d) by using the pulse current of the light source device when it can be taken out from the light source device.

  Next, the surface inspection apparatus according to the present embodiment can create a calibration curve by using the reference light amount generation light source device 100 by performing the processing shown in the flowchart of FIG. When creating the calibration curve, the operator inputs the parameter group shown in FIG. 11 in advance through the GUI or the like to the surface inspection apparatus.

  Further, in the calibration wafer data, corresponding to the input parameter group, (1) the intensity of light collected and detected by each photodetector 50 among the background scattered light generated by the calibration wafer. It is assumed that each direct current value necessary for causing each of the reference light amount generation light source devices 100 to generate a corresponding light amount is stored in advance.

  In the standard particle data table, (2) the particle size of the standard particle (3) of the scattered light generated by the standard particle having the particle size of (2) is the intensity of the light collected and detected by each photodetector 50. Data pairs of each pulse current value necessary for causing the respective light source devices 100 for generating a corresponding light amount to be generated are stored in advance for the number of types of particle sizes necessary for creating a calibration curve. It shall be.

In addition, each numerical value of (1), (2), and (3) shall be obtained with reference to the data in the said standard particle database created previously as mentioned above.
Step 1: Inspection in which the calibration curve to be created is associated with parameters related to the output signal of each photodetector 50, such as the applied voltage of the photomultiplier tube of each photodetector 50, the gain of the signal amplifier, etc. An appropriate value is set so that the output signal does not saturate and a sufficient output signal is obtained according to the conditions.
Step 2: The light detectors 50 receive only the output light of the reference light source generating light source devices 100, and the light generated from the calibration wafer by the inspection light source is the photodetector 50. So that it is not incident on.
Step 3: The rotation speed of the rotary stage and the diameter of the illumination spot used for the inspection condition associated with the calibration curve to be created, and the calibration for setting the pulse width of each of the light source devices 100 for generating the reference light amount The time calculated by the following formula is set from the value of the radius of the position where the standard particles are applied when the wafer is formed.

Illumination spot diameter / (2 x π x radius x rotation speed)
Step 4: Read out the direct current value corresponding to each photodetector 50 stored in the calibration wafer data.
Step 5: Set the value of a standard particle counter (hereinafter referred to as M) to 1.
Step 6: Read the particle diameter value, the direct current value and the pulse current value corresponding to each photodetector 50, which are stored as the Mth data set in the standard particle data table.
Step 7: The direct current value read in Step 4 and the pulse current value read in Step 6 are set in each of the reference light quantity generation light source devices 100, and light corresponding to these values is generated.
Step 8: The light emission of Step 7 is detected by each photodetector 50, and each signal intensity value (both signal intensity corresponding to the DC component and signal intensity corresponding to the pulse component) obtained at that time is read out at Step 6. The particle size value is individually stored for each photodetector 50 as the Mth data set of the calibration curve creation data table.
Step 9: Steps 6 to 8 are repeated while increasing the value of M by 1 until the processing is completed for all data in the standard particle data table.
Step 10: A calibration curve is created by performing a statistical operation such as a least square method from the data set stored in the calibration curve creation data table.

  As described above, the surface inspection apparatus of this embodiment can create a calibration curve without using a calibration wafer.

  A light meter that can measure the amount of output light by a plurality of light source devices for generating a reference light amount, the absolute value of the light amount in advance using W (watts) or the number of photons per unit time, or using these guidance unit systems. Each light source device is tested so that output light having the same intensity can be extracted from the plurality of light source devices under predetermined conditions when the set value of the direct current, the set value of the pulse current, and the set value of the pulse current are predetermined. If adjusted, calibration curve creation is performed under the same conditions among a plurality of surface inspection apparatuses incorporating each light source device, and it goes without saying that it works advantageously for suppressing the difference in sensitivity characteristics between the devices.

  As another effect, the magnitude of the output signal of each photodetector can be converted into W (watts), the number of photons per unit time, or their inductive unit system. The intensity of the generated scattered light can be displayed as an absolute value of the light amount. The light source device 100 for generating a reference light amount according to the present embodiment can be applied to various inspection apparatuses other than the present embodiment as long as the light from the light source device for generating a reference light amount can be incident on a photodetector.

  For example, if the optical fibers 20 that emit light from the light source device for generating a reference light amount are arranged in an array, light from the light source device for generating a reference light amount can be incident on each pixel of a CCD array or TDI.

  At this time, the number of optical fibers 20 arranged in an array and the number of pixels of a CCD array or TDI do not necessarily have to match.

  FIG. 12 shows an example in which light 240 from a light source device for generating a reference light quantity is incident on a one-dimensional CCD 250 using an arrayed optical fiber 20.

  Next, Example 2 will be described. In the second embodiment, the output signal when the light from the light source device of FIG. 1 is incident on the photodetector 50 is observed with an oscilloscope or the like, thereby determining the quality of the photodetector 50 incorporated in the surface inspection device. This can be performed before the inspection apparatus is assembled.

  At this time, as described above, (1) the set value to the DC current set value input unit 6 of the light source device, (2) the set value to the pulse current set value input unit 7 and the switching of the ND filter 12, (3) A value corresponding to an actual inspection condition using the surface inspection apparatus is set in the set value in the pulse width input unit 8 and (4) the set value in the pulse repetition interval input unit 9. Further, when observing the output signal of the photodetector 50, amplification or frequency filtering is appropriately performed if necessary. With these operations, it is possible to evaluate the pass / fail judgment of the photodetector 50 with respect to the light input that simulates the state when the surface inspection apparatus is actually operated.

  If this light source device is used, the test items for pass / fail judgment are: Response linearity to pulsed light emission (represents the characteristic that when the intensity of pulsed light emission is increased at a certain rate, the output increases by a corresponding amount) 2. Items relating to pulsed light emission such as saturation characteristics for pulsed light emission (representing characteristics of how much the intensity of pulsed light emission becomes saturated) can be included.

  The light source device is configured with a smaller number of parts than a general surface inspection device, and can be manufactured at low cost. Therefore, it is suitable for manufacturing a plurality of units.

  However, even if the set value to the DC current set value input unit 6 and the set value to the pulse current set value input unit 7 are the same among the plurality of light source devices manufactured, the optical fiber 20 If there is a difference in the amount of light output, there is a possibility that a different determination result can be obtained by evaluating the photodetector using different light source devices.

  In the light source device of this embodiment, in order to avoid such a possibility, the set value to the DC current set value input unit 6, the set value to the pulse current set value input unit 7, and the pulse width input unit 8 are used. When the light source device is operated with a set value for a predetermined condition, the amount of light extracted from the emission side end face of the optical fiber 20 is set to the absolute value of the amount of light in advance in W (watts) or photons per unit time. Or a light quantity meter that can be measured using the induction unit system, and a set value to the DC current set value input unit 6, a set value to the pulse current set value input unit 7, and the pulse width input The amplification values of the DC current amplifier 21 and the pulse current amplifier 31 are adjusted so that the output values having the same intensity can be extracted from all of the plurality of light source devices under the predetermined conditions set to the unit 8. To doAccording to this procedure, even when a plurality of the light source devices are used, it is possible to reduce the possibility that “a different determination result can be obtained by evaluating a photodetector using different light source devices”.

  In the light source device of this embodiment, the wavelength, light amount, and temporal change of the light amount that are scattered, diffracted, or reflected on the surface of the object to be inspected in the surface inspection device to be simulated and incident on the photodetector. However, in the case where the sensitivity of the photodetector 50 to be evaluated has polarization dependence, in addition to the above items, the characteristics of the polarization state are also simulated. It is desirable to generate an optical signal.

DESCRIPTION OF SYMBOLS 1 Light emitting element 2 DC current generation part 3 Pulse current generation part 4 Current adder 6 DC current setting value input part 7 Pulse current setting value input part 8 Pulse width input part 9 Pulse repetition interval input part 10 Condensing lens 11 Beam splitter 12 ND filter 13 switching mechanism 14 light intensity monitoring detector 20 optical fiber 21 DC current amplifier 31 pulse current amplifier 40 control microcomputer 41 reference light intensity generating light source device control interface 50 photodetector 61 DC current setting interface 71 pulse current setting interface 81 Pulse Width Setting Interface 91 Pulse Generation Timing Signal Interface 100 Reference Light Generation Light Source Device 101 Defect 111 Light Source 126 Amplifier 130 A / D Converter 140 Sampling Control Unit 150 Sampling Data Averaging Unit 200 Semiconductor Semiconductor Wafer 201 Chuck 202 Inspected object moving stage 203 Rotating stage 204 Translation stage 205 Z stage 206 Inspection coordinate detection unit 208 Defect determination unit 210 Illumination / detection optical system 220 Particle size calculation unit 230 Defect coordinate detection unit 240 Reference light quantity generator Light 250 One-dimensional CCD

Claims (20)

A first illumination optical system for supplying light to the sample;
A detection optical system for detecting light from the sample;
A second illumination optical system that supplies the detection optical system with light simulating the time characteristics of light generated from a defect of a desired dimension;
Using the results of the detection optical system detects light the simulating, have a, a processing unit for obtaining a function for converting the detection results of the detection optical system to the size of the defect during inspection,
The inspection optical system includes a sensor having a plurality of pixels, and the simulated light is supplied to the plurality of pixels . The inspection apparatus according to claim 1,
2. The inspection apparatus according to claim 1, wherein the simulated light includes a pulse component generated from the defect having the desired dimension. The inspection apparatus according to claim 2,
2. The inspection apparatus according to claim 1, wherein the simulated light includes light in a Rayleigh scattering region. The inspection apparatus according to claim 3, wherein
The second illumination optical system changes the simulated light from the Rayleigh scattering region to the Mie scattering region. The inspection apparatus according to claim 4,
The simulated light includes a direct current component corresponding to a surface state of a sample to be inspected. The inspection apparatus according to claim 5, wherein
The second illumination optical system includes:
A light emitting device for generating the simulated light;
A pulse current generation system for generating a pulse current for driving the light emitting element;
A direct current generation system for generating a direct current for driving the light emitting element;
A detection system for detecting a part of the light from the light emitting element,
The inspection apparatus, wherein the pulse current generation system and the direct current generation system change the pulse current and the direct current so that an output of the detection system becomes a desired value. The inspection apparatus according to claim 5, wherein
An inspection apparatus comprising a neutral density filter disposed so as to be able to enter and exit the optical path of the second illumination optical system. The inspection apparatus according to claim 1,
2. The inspection apparatus according to claim 1, wherein the simulated light includes light in a Rayleigh scattering region. The inspection apparatus according to claim 8, wherein
The second illumination optical system changes the simulated light from the Rayleigh scattering region to the Mie scattering region. The inspection apparatus according to claim 2,
The simulated light includes a direct current component corresponding to a surface state of a sample to be inspected. The inspection apparatus according to claim 1.
The simulated light includes a first simulated light and a second simulated light,
The inspection apparatus, wherein the first simulated light is supplied to a first pixel of the sensor, and the second simulated light is supplied to a second pixel of the sensor . Supplying light simulating the time characteristics of light generated from defects of desired dimensions to a plurality of pixels that detect light from the sample;
Adjustment of the inspection apparatus characterized in that a function for converting the detection result of the detection optical system into a defect size is obtained at the time of inspection using the result of detection of the simulated light by the detection optical system Method. The adjustment method according to claim 12,
The adjustment method, wherein the simulated light includes a pulse component generated from the defect having the desired dimension . The adjustment method according to claim 13,
The adjustment method, wherein the simulated light includes light in a Rayleigh scattering region . The adjustment method according to claim 14,
An adjustment method, wherein the simulated light is changed from the Rayleigh scattering region to the Mie scattering region . In the adjustment method according to claim 1 5,
The adjustment method, wherein the simulated light includes a direct current component corresponding to a surface state of a sample to be inspected . In the adjustment method according to claim 1 2,
The adjustment method, wherein the simulated light includes light in a Rayleigh scattering region . The adjustment method according to claim 17,
An adjustment method, wherein the simulated light is changed from the Rayleigh scattering region to the Mie scattering region . The adjustment method according to claim 12,
The adjustment method, wherein the simulated light includes a direct current component corresponding to a surface state of a sample to be inspected. The adjustment method according to claim 12,
  The simulated light includes a first simulated light and a second simulated light,
  An adjustment method for supplying the first simulated light to the first pixel and supplying the second simulated light to the second pixel.

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