JP2004347483A - Pattern inspection device using electron beam and pattern inspection method using electron beam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pattern inspection device using an electron beam, capable of enhancing the detection precision of a desired flaw. <P>SOLUTION: In the pattern inspection device using the electron beam, for inspecting the pattern formed on the surface of a sample by forming an image to be inspected by irradiating the sample with the electron beam to detect the secondary electrons or reflected electrons emitted from the sample and comparing the same with a reference image, the caliblation of the brightness of the image to be inspected and that of the reference image is performed to detect the desired flaw such as a flaw bright or dark with respect to a normal part, or the like. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inspection apparatus and an inspection method for a semiconductor device such as a memory or an LSI having a fine circuit pattern and a circuit pattern such as a liquid crystal and a photomask, and more particularly to a pattern inspection apparatus and an inspection method using an electron beam.
[0002]
[Prior art]
2. Description of the Related Art A semiconductor device is manufactured by repeating a process of transferring a circuit pattern formed on a semiconductor wafer on a photomask by lithography and etching. The quality of lithography, etching, and other processes in the manufacturing process of a semiconductor device, the generation of foreign matter in the manufacturing process, and the like greatly affect the yield of the semiconductor device. Therefore, in order to detect the occurrence of processing abnormality or defect early or in advance, it is necessary to inspect a pattern formed on a semiconductor wafer in a manufacturing process for each process.
[0003]
In the process of manufacturing semiconductor devices, an optical inspection device that determines abnormalities using images obtained by irradiating a pattern with laser light or the like, and secondary electrons generated by scanning a pattern with a charged particle beam such as an electron beam An SEM-type inspection apparatus that determines an abnormality using signal intensity or an image from reflected electrons or reflected electrons is used. Here, SEM is a scanning electron microscope
(Scanning Electron Microscope).
[0004]
In a pattern inspection apparatus using an electron beam, that is, in an SEM inspection apparatus, an image signal is obtained by binarizing an electric signal proportional to the amount of detected secondary electrons or reflected electrons, and an inspection image is compared with a reference image. The defect is detected by regarding the difference in image signal amount, that is, the difference in brightness as a defect. Utilizing the fact that chips on a semiconductor wafer are a repetition of the same pattern, a defect can be extracted by comparing the image immediately before the inspection image with a reference image, and the memory capacity for storing the image is small. Yes. However, even in a normal part, a slight difference in brightness due to a process may be erroneously detected as a defect, and if the brightness of the entire image changes due to noise superposition or the like, the brightness of the entire image may change. Even if two images having a difference are compared, it is not clear where the defect is, and there is a problem that a desired defect cannot be detected.
[0005]
On the other hand, a technique of providing an image brightness adjustment function in an SEM type inspection apparatus is also known, but it is not clear how the adjustment is performed, and a defect that looks brighter than the surroundings or a darkness appears on the image. Since all the extracted defects are output as defects without distinguishing the defects, it has been difficult to detect a desired defect (for example, see Patent Document 1).
[0006]
[Patent Document 1]
JP-A-2000-193594 (page 13, page 15, FIG. 12)
[0007]
[Problems to be solved by the invention]
Conventionally, only desired defects could not be detected by the SEM type inspection device, and only the desired defects were obtained by observing and classifying the extracted defects with an observation device. It took a long time to identify, and we could not respond quickly.
[0008]
SUMMARY OF THE INVENTION An object of the present invention is to provide a pattern inspection apparatus and an inspection method using an electron beam, which improve the detection accuracy of a desired defect.
[0009]
[Means for Solving the Problems]
In order to solve the above object, an embodiment of the present invention forms an image by irradiating an electron beam on a sample having a pattern formed on its surface and detecting secondary electrons and reflected electrons generated from the sample, An electron beam pattern inspection apparatus that compares an inspection target image with a reference image and inspects a pattern includes an operation unit that calibrates the brightness of the inspection target image and the reference image and detects only a desired defect. It is a thing.
[0010]
Further, when performing the calibration of the brightness of the inspection target image and the reference image in a direction in which the brightness of the desired defect becomes brighter, a defect darker than the brightness after the calibration is detected, and the brightness of the desired defect is compared with the brightness of the desired defect. When darkening, a defect brighter than the brightness after calibration is detected.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0012]
FIG. 1 is a longitudinal sectional view schematically showing a configuration of an SEM type inspection apparatus for inspecting a pattern of a semiconductor wafer or a mask or a reticle using an electron beam to which the present invention is applied. The SEM type inspection apparatus 1 is roughly divided into an inspection room 2 including an electron optical system device 3, an optical microscope unit 4, and a sample room 8, an image processing unit 5, a control unit 6, and a secondary electron detection unit 7. Consists of
[0013]
The electron optical system device 3 includes an electron gun 10, an electron beam extraction electrode 11, a condenser lens 12, a blanking deflector 13, a diaphragm 14, a scanning deflector 15, an objective lens 16, a reflection plate 17, and an E × B deflector 18. An electron beam 19 generated by the electron gun 10 and extracted by the extraction electrode 11 irradiates the sample 9 through the condenser lens 12, the aperture 14, and the objective lens 16. The electron beam 19 is a narrowed beam, and the sample 9 is scanned by the scanning deflector 15, and reflected electrons and secondary electrons 51 are generated from the sample 9. The secondary electrons have their trajectories bent by the E × B deflector 18 and irradiate the reflector 17, generating second secondary electrons 52, which are detected by the secondary electron detector 20. On the other hand, by directing the electron beam 19 to the outside of the opening of the stop 14 by the blanking deflector 13, the irradiation of the sample 9 with the electron beam 19 can be prevented.
[0014]
The sample chamber 8 includes a sample stage 30, an X stage 31, a Y stage 32, a rotary stage 33, a position monitor length measuring device 34, and a sample height measuring device 35. The optical microscope unit 4 is provided near the electron optical system device 3 in the inspection room 2 and at a position away from the electron optical system device 3 so as not to affect each other. Is known. Then, the X stage 31 or the Y stage 32 reciprocates a known distance between the electron optical system device 3 and the optical microscope unit 4.
[0015]
The optical microscope unit 4 includes a white light source 40, an optical lens 41, and a CCD camera 42. Although not shown, an acquired image is sent to the image processing unit 5 in the same manner as an electron beam image described later.
[0016]
In this embodiment, a length measuring device based on laser interference is used as the position monitor measuring device 34. The positions of the X stage 31, the Y stage 32, and the rotating stage 33 can be monitored in real time, and the position information can be sent to the control unit 6. Although not shown, data such as the number of rotations of the motors of the X stage 31, the Y stage 32, and the rotation stage 33 are also transmitted from the respective drivers to the controller 6. The control unit 6 can accurately grasp the region and position where the electron beam 19 is irradiated based on these data, and corrects the positional deviation of the irradiation position of the electron beam 19 in real time as necessary. The correction can be performed using the control circuit 43. Further, even if the sample 9 is replaced, the region irradiated with the electron beam can be stored for each sample.
[0017]
As the sample height measuring device 35, an optical measuring device using a measuring method other than the electron beam, for example, a laser interferometer or a reflected light measuring device for measuring a change in the position of reflected light is used. The configuration is such that the height of the sample 9 mounted on the Y stage 31 can be measured in real time. In the present embodiment, a method in which an elongated white light passing through a slit is applied to a sample 9 through a transparent window, the position of reflected light is detected by a position detection monitor, and a height change amount is calculated from a position change. Was used. Based on the measurement data of the sample height measuring device 35, the focal length of the objective lens 16 for narrowing down the electron beam 19 is dynamically corrected so that the electron beam 19 can be always focused on the inspection area. It has become. Further, it is also possible to configure so that the warpage and the height distortion of the sample 9 are measured in advance before the electron beam irradiation, and the correction conditions for each inspection area of the objective lens 16 are set based on the data. .
[0018]
In order to obtain an image of the sample 9, the electron beam 19 narrowed down is irradiated on the sample 9 to generate secondary electrons 51, which are scanned by the electron beam 19 and moved by the X stage 31 and the Y stage 32. Synchronously detect.
[0019]
The electron beam 19 is extracted from the electron gun 10 by applying a voltage between the electron gun 10 and the extraction electrode 11. The electron beam 19 is accelerated by applying a high negative voltage to the electron gun 10. As a result, the electron beam 19 advances toward the sample stage 30 with energy corresponding to the potential, is converged by the condenser lens 12, is further narrowed down by the objective lens 16, and is narrowed down by the X stage 31 and the Y stage 32 on the sample stage 30. The sample 9 mounted on the rotating stage 33 is irradiated.
[0020]
A scanning signal generator 44 for generating a scanning deflection signal and a blanking signal is connected to the blanking deflector 13, and an objective lens power supply 45 is connected to the objective lens 16. A negative voltage can be applied to the sample 9 by the retarding power supply 36. By adjusting the voltage of the retarding power supply 36, the primary electron beam can be decelerated, and the irradiation energy of the electron beam to the sample 9 can be adjusted to an optimum value without changing the potential of the electron gun 10. When it is necessary to blank the electron beam 19, the electron beam 19 is deflected by the blanking deflector 13, and the electron beam 19 can be controlled so as not to pass through the aperture 14.
[0021]
Secondary electrons 51 generated by irradiating the sample 9 with the electron beam 19 are accelerated by the negative voltage applied to the sample 9. The E × B deflector 18 is disposed above the sample 9, and the accelerated secondary electrons 51 are deflected in a predetermined direction. The deflection amount can be adjusted by the voltage applied to the E × B deflector 18 and the strength of the magnetic field. Further, this electromagnetic field can be changed in conjunction with a negative voltage applied to the sample. The secondary electrons 51 deflected by the E × B deflector 18 collide with the reflector 17 under predetermined conditions. The reflection plate 17 has a conical shape, and the electron beam 19 passes through an opening provided at the center thereof. When the accelerated secondary electrons 51 collide with the reflector 17, a second secondary electron 52 having an energy of several V to 50 eV is generated from the reflector 17.
[0022]
The secondary electron detector 20 is disposed above the objective lens 16 in the inspection room 2 and detects the second secondary electrons 52. The output signal of the secondary electron detector 20 is provided outside the inspection room 2. The amplified data is amplified by the preamplifier 21, converted into digital data by the AD converter 22, and transmitted from the light conversion unit 23 to the electric conversion unit 25 of the image processing unit 5 by the light transmission unit 24. When the reflection plate 17 is not provided, the secondary electrons 51 may be detected by the secondary electron detector 20 instead of the second secondary electrons 52.
[0023]
The high-voltage power supply 26 supplies a preamplifier driving power supply 27 for driving the preamplifier 21, an AD converter driving power supply for driving the AD converter 22, and a voltage to be applied to the secondary electron detector 20 to attract the second secondary electrons. Power is supplied to the reverse bias power supply 29. The second secondary electrons 52 generated by colliding with the reflection plate 17 are guided to the secondary electron detector 20 by an attraction electric field generated by the secondary electron detector 20 by the supply of the reverse bias power supply 29.
[0024]
The secondary electron detector 20 detects a second secondary electron 52 generated while the secondary electron 51 generated while the electron beam 19 is irradiated on the sample 9 is then accelerated and collides with the reflecting plate 17, The detection is performed in conjunction with the scanning timing of the electron beam 19.
[0025]
The output signal of the secondary electron detector 20 is amplified by a preamplifier 21 installed outside the inspection room 2, and converted into digital data by an AD converter 22. The AD converter 22 is configured to convert an analog signal detected by the secondary electron detector 20 into a digital signal immediately after being amplified by the preamplifier 21 and transmit the digital signal to the image processing unit 5. As described above, since the detected analog signal is digitized and transmitted immediately after the detection, a signal having a high speed and a high SN ratio can be obtained.
[0026]
The sample 9 is mounted on the X stage 31 and the Y stage 32. During the inspection, the electron beam 19 is moved in the X direction by moving the X stage 31 and the Y stage 32 continuously at a constant speed in the Y direction. The electron beam 19 can be linearly scanned in the Y direction by moving the X stage 31 and the Y stage 32 continuously at a constant speed in the X direction. .
[0027]
The image processing unit 5 includes a first storage unit 46, a second storage unit 47, a calculation unit 48, a defect determination unit 49, and a monitor 50. The captured electron beam image or optical image is displayed on the monitor 50. Operation commands and operation conditions of each unit of the device are input and output from the control unit 6. In the control unit 6, conditions such as acceleration voltage at the time of electron beam generation, electron beam deflection width, deflection speed, signal fetch timing of the secondary electron detector 20, and moving speed of the sample stage 30 are arbitrarily set according to the purpose. Is entered so that it can be selected or set. The control unit 6 uses the correction control circuit 43 to
34, monitor the position and height deviation from the signal of the sample height measuring device 35, generate a correction signal based on the result, and supply the objective lens 16 The correction signal of the blanking deflector 13 is sent to the scanning signal generator 44.
[0028]
The image signal of the sample 9 transmitted by the optical transmission unit 24 is converted into an electric signal again by the electric conversion unit 25 and stored in the first storage unit 46 or the second storage unit 47.
[0029]
The arithmetic unit 48 performs alignment of the stored image signal with the image signal of the other storage unit, normalizes the signal level, performs various image processing for removing a noise signal, and compares the two image signals. Calculate. The calibration described later is performed here.
[0030]
The defect determination unit 49 compares the absolute value of the difference image signal calculated and compared by the calculation unit 48 with a predetermined threshold value, and when the difference image signal level is larger than the predetermined threshold value, determines the pixel as a defect candidate. The monitor 50 displays the position, the number of defects, and the like. This predetermined threshold is called an inspection threshold.
[0031]
In the above-described embodiment, the secondary electron detector 20 is applied with the reverse bias voltage from the reverse bias power supply 29. However, the secondary electron detector 20 may be configured not to apply the reverse bias voltage. In the present embodiment, a PIN type semiconductor detector is used as the secondary electron detector 20, but another type of semiconductor detector, for example, a Schottky type semiconductor detector or an avalanche type semiconductor detector may be used. . If conditions such as responsiveness and sensitivity are satisfied, an MCP (micro channel plate) can be used as a detector.
[0032]
Next, a procedure for inspecting the semiconductor wafer on which pattern processing has been performed in the manufacturing process by the SEM inspection apparatus 1 shown in FIG. 1 will be described.
[0033]
FIG. 2 is a flowchart showing the procedure of the inspection. First, a cassette in which wafers are set on an arbitrary shelf is placed on a cassette mounting portion (step 53 in FIG. 2). Next, a wafer to be inspected is specified from the monitor 50, and thereafter, various inspection conditions are input (step 54 in FIG. 2). As the inspection condition, an electro-optical condition, the number of times of addition of an image signal, an inspection pixel size and the like are input. When these condition inputs are completed, the inspection is started (step 55 in FIG. 2). When the automatic inspection is started, first, the designated wafer is loaded into the sample exchange chamber (Step 56 in FIG. 2). Thereafter, the sample exchange chamber is evacuated after being mounted and fixed on the sample holder, and is transferred to the inspection chamber 2 when the sample exchange chamber reaches a certain degree of vacuum. In the inspection room 2, the sample holder is placed on the sample table 30 via the X stage 31, the Y stage 32, and the rotating stage 33 and held and fixed. When the wafer is loaded, the control unit 6 sets the conditions of the electron optical system based on the input inspection conditions. Then, focus and astigmatism are adjusted by beam calibration (step 57 in FIG. 2). Then, the wafer is moved to a predetermined position on the wafer, an SEM image is obtained, and contrast and the like are adjusted (Step 58 in FIG. 2). Here, when a change in conditions such as the electron beam irradiation energy occurs, it is possible to change the parameters and perform beam calibration again. At the same time, the height of the wafer is obtained from the height detector, and the correlation between the height information and the focusing condition of the electron beam is obtained by the wafer height detection system. The focus condition is automatically adjusted based on the result of the wafer height detection. Thereafter, alignment is performed at two points on the wafer (step 59 in FIG. 2).
[0034]
In order to execute automatic alignment, an optical microscope image and an SEM image and position information of an alignment chip, a pattern or a pattern suitable for alignment are obtained and registered in advance using a wafer having a pattern equivalent to the wafer to be observed. In the inspection condition input, the preset coordinates and the registered image can be read out. In the inspection, it is necessary to accurately view a set area in a wafer or a chip. Therefore, the alignment is automatically executed using the alignment conditions and the alignment image registered in advance before executing the viewing of the defective portion. In the alignment, when the alignment pattern on the first chip exists, the sample stage 30 is moved to the coordinates registered in the inspection condition file, an image is first acquired by an optical microscope, and the registered optical system is obtained by image processing. A position that matches the microscope image is automatically searched, and if detected, the coordinates of the detected point are calculated by calculation. Also, an SEM image of the same location is acquired based on the detected coordinates, a location that matches the registered SEM image is automatically searched by image processing, and if detected, the coordinates of the detected point are calculated by calculation. Are stored as coordinates. Next, with respect to the second chip located at a parallel position on the circuit pattern matrix, the stage similarly moves to a position where the alignment pattern is considered to exist. Therefore, similarly to the first point, the optical microscope image and the SEM image are respectively searched for a position that matches the registered image by image processing, the coordinates of the detected position are calculated by calculation, and stored as the coordinates of the second point. . Coordinate shift between two points between the first expected position calculated from the alignment mark position on the chip and the data of the chip size and the coordinate position obtained by actually acquiring an image, that is, the X direction The amount of rotation θ of the circuit pattern array on the wafer with respect to the stage movement direction is obtained from the deviation amount in the Y direction, and the amount of correction in the electron beam scanning direction is determined from the amount of rotation θ. When the alignment is completed, the rotation and the coordinate values are corrected based on the alignment result, and then moved on the wafer to obtain images of several patterns, and the brightness adjustment calibration is performed (step in FIG. 2). 60). The calibration method will be described later in detail.
[0035]
When the calibration is completed, an inspection is performed (Step 61 in FIG. 2). Here, an inspection method for detecting a pn junction leak defect and a plug conduction defect as electrical defects in a wafer will be described. In the structure of the sample, an element isolation layer is formed on a substrate, and each transistor is separated by the element isolation layer. The transistor portion has a hole pattern in which a plug is embedded, and the substrate and the plug are electrically connected, but the plug pattern has a structure surrounded by an interlayer insulating film. Then, a pn junction is formed in the substrate portion immediately below the plug. In this example, a p-type substrate was used as the substrate, and a film of polysilicon doped with n-type ions was used as the plug filling material. An electron beam is incident on such a sample. Here, as the irradiation energy of the electron beam, a condition in which the secondary electron emission efficiency of the plug portion is larger than 1 is selected. In this embodiment, the irradiation energy was set to 500 eV. The electron beam current was set to 100 nA, and the beam scanning speed and the signal sampling clock were set to 50 MHz. These irradiation conditions can be arbitrarily set within a specified range. For example, the electron beam current can be set in a range from 10 pA to 150 nA, and the sampling clock can be set in a range from 100 kHz to 100 MHz.
[0036]
When the sample is irradiated with the electron beam under the above conditions, more secondary electrons are generated than the irradiated electron beam. As a result, the plug portion is electrically positively charged. The plug is electrically connected to the substrate, but has a pn junction. A pn junction has a depletion layer at the junction limit, and a current flows when a potential is applied to a forward bias, but does not flow when a potential is applied to a reverse bias. In this embodiment, since the plug surface corresponding to the n region is electrically positively charged, the plug is in a reverse bias state. Therefore, no current flows from the substrate corresponding to the p region, and the supply of electrons is extremely small. Therefore, it takes a long time for the charged electric charge to relax. If a leak occurs at the pn junction, the supply of electrons from the substrate becomes relatively large, so that the potential contrast image is displayed brighter than the normal plug portion. Further, if there is a conduction failure in the plug portion, the supply of electrons from the substrate is stopped, so that the potential contrast image is displayed darker than the normal plug portion.
[0037]
In the inspection procedure, these detected defects are reviewed for potential leakage or conduction failure using a potential contrast image, and the images are stored as necessary (step 62 in FIG. 2). Then, as a result of the inspection, the state of distribution of defects on the wafer is displayed on the monitor 50, and output to the outside as necessary (step 63 in FIG. 2). In this way, when the inspection is completed, the wafer is unloaded and the process ends (step 64 in FIG. 2).
[0038]
Hereinafter, the calibration method will be described. Calibration detects the images of multiple points in the inspection area, takes a histogram of the secondary electron signal amount, and detects the secondary electron signal amount detection sensor in order to respond to the secondary electron signal amount variation caused by the process for each wafer. And a gradation conversion table for image processing.
[0039]
First, a first example of calibration will be described. FIG. 3 is a diagram showing a relationship between brightness before and after gradation conversion at the time of calibration, and is an example of a gradation conversion table. First, the sensor gain is set so that the amount of the secondary electron signal does not saturate, and the distribution range of the amount of the secondary electron signal is determined by cutting the upper and lower 0.1% of the histogram of the calibration points acquired under the conditions. , The distribution range of the secondary electron signal amount is arbitrarily expanded, and a gradation conversion table is set to detect the range. In this embodiment, the maximum value of the brightness before the gradation conversion is set to 255 bits, and the corresponding brightness X after the gradation conversion is obtained. FIG. 4 is a diagram of an image displayed on a monitor of the SEM type inspection apparatus, and shows a detection image 70 of a hole pattern in which a plug is embedded in a wafer. In the case of the first example of the calibration, both the darker hole pattern 72 and the lighter hole pattern 73 are detected as defects with respect to the brightness of the hole pattern 71 having no defect. In the case of defect extraction by image comparison, a dark hole pattern 72 and a light hole pattern 73 can be extracted by comparing the inspection image shown in FIG.
[0040]
Next, a second example of calibration will be described. This example is an example of calibration in a case where it is desired to detect only a defect in which a hole pattern is displayed dark due to a conduction failure in a plug portion. FIG. 5 is a relationship diagram of brightness before and after gradation conversion, and shows an example of a gradation conversion table. The sensor gain is increased to a certain extent toward the brighter side, and a gradation conversion table similar to that in the first example is set. FIG. 6 is a diagram of an image displayed on the monitor of the SEM inspection apparatus, and shows a detection image 74 of a hole pattern in which a plug is embedded in a wafer, as in FIG. In the case of this calibration, the brightness of the hole pattern 75 having no defect is substantially the same as the brightness of the bright hole pattern 76 caused by the leak in the plug portion because the brightness is somewhat saturated on the bright side. By comparing the inspection image with a reference image having no defect and taking a difference, only the dark hole pattern 77 can be detected.
[0041]
Next, a third example of calibration will be described. This example is an example of calibration when it is desired to detect only a defect in which a hole pattern is displayed brightly due to a leak in a plug portion. FIG. 7 is a relationship diagram of brightness before and after gradation conversion, and shows an example of a gradation conversion table. The sensor gain is lowered toward the dark side so as to be saturated to some extent, and a gradation conversion table similar to that of the first example is set. FIG. 8 is a diagram of an image displayed on the monitor of the SEM type inspection apparatus, and shows a detection image 78 of a hole pattern in which a plug is embedded in a wafer, similarly to FIG. In the case of this calibration, the brightness of the hole pattern 79 having no defect is substantially the same as the brightness of the dark hole pattern 80 caused by poor conduction in the plug portion because the dark side is saturated to some extent. By comparing the inspection image with a reference image having no defect and taking a difference, only the bright hole pattern 81 can be detected.
[0042]
In this way, it becomes possible to detect only a dark defect or a bright defect. If the cause of the defect and how it looks in the image are known in advance, as in the present embodiment, the pattern is adjusted using an electron beam by adjusting the calibration to detect only the desired defect. The defect can be classified by the inspection device. Conventionally, the coordinate information of various detected defects is transmitted to a defect observation device, and each defect is observed by the defect observation device to perform defect classification work. According to the embodiment of the present invention, the defect can be classified by the pattern inspection apparatus using the electron beam, and the distribution of only the desired defect in the wafer surface can be obtained. Quick response such as identification of the cause of defect occurrence is possible.
[0043]
As described above, according to the present embodiment, by calibrating the brightness of the inspection target image and the brightness of the reference image and comparing them, it is not necessary to perform the work such as classification after the end of the inspection, and it is brighter than the normal part. Desired defects such as defects and dark defects can be easily detected.
[0044]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a pattern inspection apparatus using an electron beam that improves the accuracy of detecting a desired defect.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view schematically showing the configuration of an SEM type inspection apparatus.
FIG. 2 is a flowchart showing a procedure of an inspection.
FIG. 3 is a diagram showing a relationship between brightness before and after gradation conversion.
FIG. 4 is a diagram of an image displayed on a monitor of the SEM type inspection apparatus.
FIG. 5 is a diagram showing a relationship between brightness before and after gradation conversion.
FIG. 6 is a diagram of an image displayed on a monitor of the SEM type inspection device.
FIG. 7 is a diagram showing a relationship between brightness before and after gradation conversion.
FIG. 8 is a diagram of an image displayed on a monitor of the SEM type inspection apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... SEM type inspection apparatus, 2 ... Inspection room, 3 ... Electronic optical system apparatus, 4 ... Optical microscope part, 5 ... Image processing part, 6 ... Control part, 7 ... Secondary electron detection part, 8 ... Sample room, 9 ... sample, 10 ... electron gun, 11 ... electron extraction electrode, 12 ... condenser lens, 13 ... blanking deflector, 14 ... stop, 15 ... scanning deflector, 16 ... objective lens, 17 ... reflector, 18 ... E × B deflector, 19 ... electron beam, 20 ... secondary electron detector, 21 ... preamplifier, 22 ... AD converter, 23 ... light conversion means, 24 ... light transmission means, 25 ... electric conversion means, 26 ... high voltage power supply , 27: Preamplifier drive power supply, 29: Reverse bias power supply, 30: Sample stage, 31: X stage, 32: Y stage, 33: Rotating stage, 34: Position monitor length measuring instrument, 35: Sample height measuring instrument, 36 ... retarding power supply, 40 ... white light source, 4 ... optical lens, 42 ... CCD camera, 43 ... correction control circuit, 44 ... scanning signal generator, 45 ... objective lens power supply, 46 ... first storage unit, 47 ... second storage unit, 48 ... calculation unit, 49 ... defect Judgment unit, 50 monitor, 51 secondary electron, 52 secondary electron.

Claims (5)

An image is formed by irradiating an electron beam on a sample having a pattern formed on its surface and detecting secondary electrons and reflected electrons generated from the sample, performing a comparison between an inspection object image and a reference image, and comparing the pattern. An electron beam pattern inspection apparatus for inspecting, comprising: a calculation unit for calibrating the brightness of the inspection target image and the reference image and detecting a desired defect; apparatus. 2. The pattern using an electron beam according to claim 1, wherein the calculation unit performs the calibration of the brightness of the inspection target image and the reference image in a direction brighter than the brightness of the desired defect. Inspection equipment. 2. The pattern using an electron beam according to claim 1, wherein the calculation unit performs the calibration of the brightness of the inspection target image and the reference image in a direction darker than the brightness of the desired defect. Inspection equipment. An image is formed by irradiating an electron beam on a sample having a pattern formed on its surface and detecting secondary electrons and reflected electrons generated from the sample, performing a comparison between an inspection object image and a reference image, and comparing the pattern. In a pattern inspection method using an electron beam to be inspected, a brightness of the inspection target image and the reference image is calibrated, and a desired defect is detected, wherein the pattern inspection method uses an electron beam. 5. The method according to claim 4, wherein when the calibration of the brightness of the inspection target image and the reference image is performed in a direction brighter than the brightness of the desired defect, a defect darker than the brightness after the calibration is detected. A pattern inspection method using an electron beam, wherein when performing the operation in a direction darker than the brightness of the desired defect, a defect brighter than the brightness after calibration is detected.

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