JP2007019034A - Electron beam device and defect inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a destruction of a sample by discharging between a sample applied with a high voltage and an objective lens. <P>SOLUTION: The electron beam device makes an electron beam emitted from an electron gun irradiate on a sample and evaluates the sample. The electron beam device impresses negative high voltage to the sample, includes a measuring instrument detecting a discharging precursor phenomenon between the sample and an objective lens and a function capable of adjusting voltage or current applying to the sample at or below discharging voltage or current from the measuring instrument. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

Detailed Description of the Invention

TECHNICAL FIELD OF THE INVENTION

    The present invention relates to an apparatus for performing evaluation of a sample having a pattern with a minimum line width of 0.1 μm or less at a high throughput, and a device capable of improving yield by evaluating a wafer in the middle of a process using such an apparatus. It relates to a manufacturing method.

Conventional technology

    Conventionally, in an evaluation apparatus such as a defect inspection apparatus or a CD measurement apparatus, an electron gun having a Schottky cathode has been used.

    In order to improve the throughput of evaluation, an apparatus having a plurality of emitters arranged in a straight line and a multi-detector using a line sensor has been proposed.

    Furthermore, in the conventional electron beam apparatus, an EXB deflector is used to separate the secondary electron beam from the primary electron beam. However, in the conventional EXB deflector, the deflection amount of the electrostatic deflector and the deflection amount of the electromagnetic deflector are different. The absolute values were equal and the deflection directions were opposite to each other.

    However, in a device having a Schottky cathode, for example, W / ZrO, and a cathode, there is a problem that a signal with a good S / N ratio cannot be obtained unless a large beam current is passed because the shot noise is large.

    In addition, in a multi-beam device using an emitter array and a line sensor arranged on a line, it is difficult to satisfy the imaging conditions of the primary optical system and the secondary optical system at the same time, so a practical device is still completed. The fact is not.

Furthermore, those using the conventional EXB deflector have large deflection chromatic aberration, and it has been difficult to perform accurate evaluation.
One problem to be solved by the present invention is an electron gun equipped with an electron gun with low shot noise, capable of forming and detecting a multi-beam without burdening the optical design, and performing evaluation with higher throughput. A line device is provided.

Another problem to be solved by the present invention is to provide an electron beam apparatus capable of reducing the deflection chromatic aberration of the EXB separator.
Another problem to be solved by the present invention is to provide a device manufacturing method capable of improving the yield by using the apparatus as described above.

    The invention according to claim 1 of the present application is an electron beam apparatus that irradiates a sample with an electron beam emitted from an electron gun and evaluates the sample, and applies a negative high voltage to the sample. It has a measuring device that detects the precursor phenomenon of discharge between the sample and the objective lens, and has the function of adjusting the voltage or current applied to the sample to the discharge voltage or the discharge current or less from the signal of the measuring device. It is characterized by things.

According to the present invention, it is possible to detect the discharge precursor phenomenon occurring between the sample and the objective lens and to avoid the rise of the discharge, so there is no possibility of damaging the irradiation region of the sample and the objective lens.
The invention according to claim 2 of the present application is characterized in that, in the invention according to claim 1, the measuring device comprises a photomal that detects corona discharge. In the present invention, the measuring instrument comprises an ammeter for detecting an abnormal current.

    The invention according to claim 4 of the present application includes an electron gun that emits an electron beam, a primary optical system that irradiates the sample surface to be inspected with the electron beam from the electron gun, and the sample. A secondary optical system for causing the emitted secondary electrons to enter the secondary electron detector, and the electron gun is provided corresponding to the cathode having a plurality of protrusions and the protrusions of the cathode It has a Wehnelt provided with a hole, and an adjusting mechanism for adjusting the parallelism between the surface formed by the tips of the plurality of projections of the cathode and the surface of the Wehnelt.

According to the present invention, the difference in the amount of electron emission from the plurality of emitters is small, and the beam current or beam diameter between the plurality of beams can be made uniform.
The invention according to claim 5 of the present application is characterized in that, in the invention according to claim 4, the adjusting mechanism includes a screw and a spring.

    The invention according to claim 6 of the present application is a defect inspection method in which an electron beam emitted from an electron gun is applied to a sample and the sample is evaluated, and the sample is discharged in a region within a defective chip in the sample. It is characterized by investigating conditions that cause The sample is a wafer having a defective chip in the peripheral portion, and the condition under which the discharge between the sample and the objective lens does not occur in the defective chip region in the peripheral portion of the wafer is examined.

    Since the defective chip is not used as a product, there is no problem even if it is destroyed. Therefore, it is possible to reliably prevent discharge by grasping the conditions that do not cause discharge by using these defective chip regions.

    In the first embodiment of the present application, an electron beam emitted from an electron gun having a thermionic emission cathode is made incident on a plurality of apertures, the electron beam formed in each aperture is reduced, focused on the sample surface, and scanned. In the electron beam apparatus in which the secondary electron image emitted from the sample is enlarged by at least one stage of lens and deflected from the primary optical system and detected by the secondary electron detector, the secondary electron detector has one substrate. Or a MCP (microchannel plate) detector capable of independently detecting a plurality of beams.

    By using a thermionic emission cathode, shot noise can be reduced, and a good evaluation of the S / N ratio can be performed with a smaller beam current. In addition, since a multi-detector in which secondary electron detectors are integrated on a single substrate, for example, a Si substrate, or an MCP (microchannel plate) detector capable of independently detecting a plurality of beams can be made small, It is not necessary to enlarge the secondary electron image so much, the secondary optical system can be configured simply, and detection can be performed with an efficiency close to 100% without crosstalk. Furthermore, the detection optical system can be reduced in size.

    The second embodiment of the present application has a function in which an electron gun, a condenser lens, and an objective lens are arranged in a substantially vertical direction, and a primary electron is scanned on a sample surface by a two-stage deflector. In the device for directing the secondary electrons from the direction of the detector by an electric field and a magnetic field, the aberration generated by the first stage deflector, the aberration generated by the electrostatic deflector in the second stage deflector, The electrostatic and electromagnetic deflection ratio of the second stage deflector has been adjusted so as to minimize the sum of the aberration generated by the electromagnetic deflector in the second stage deflector and the aberration of the objective lens. Features.

According to this embodiment, the deflection chromatic aberration due to the second stage deflector can be made substantially zero, and the barrel of the primary optical system can be made almost vertical.
The third embodiment of the present application has a stage for holding and moving the sample in the first or second embodiment, and further includes a laser length measuring device for measuring the movement of the stage, The moving mirror of the laser length measuring device is attached to the stage, and the fixed mirror is attached to the outside of the objective lens.

    According to this embodiment, since the fixed mirror of the laser length measuring device (interferometer) is attached to the outer cylinder of the objective lens, there is no error in the evaluation position even if there is a vibration or a temperature change. A good evaluation can be made.

    In the fourth embodiment of the present application, in the first or second embodiment, a negative high voltage is applied to the sample, and a precursor phenomenon of discharge between the sample and the objective lens is detected. It has a measuring device and has a function of adjusting the voltage or current applied to the sample to a discharge voltage or a discharge current or less from the signal of the measuring device.

    According to this embodiment, it is possible to detect a discharge precursor phenomenon occurring between the sample and the objective lens and to avoid the rise of the discharge, and there is no possibility of damaging the irradiation region of the sample and the objective lens.

    In the fifth embodiment of the present application, in the first or second embodiment, the electron gun includes a cathode having a plurality of electron beam emission regions, a Wehnelt, and an anode, and the electron beam emission region and the Wehnelt And a plurality of electron beam emission regions having a function of being able to be uniformly adjusted before being incorporated into the apparatus.

According to this embodiment, the difference in the amount of electron emission from the plurality of emitters is small, and the beam current or beam diameter between the plurality of beams can be made uniform.
The sixth embodiment of the present application is characterized in that, in the first or second embodiment, the plurality of openings are an even number, and the intervals at which the openings are projected in one axial direction are equal intervals. To do.

According to this embodiment, there is no difference in the spacing between the plurality of beams, and a beam close to symmetry around the optical axis can be obtained. Further, it is possible to perform a scan without waste.
The seventh embodiment of the present application is characterized in that, in the fifth embodiment, the maximum values of the adjacent beam intervals around the optical axis are equal at four positions.

According to this embodiment, with the above conditions, the difference between the maximum value and the minimum value of the beam interval around the optical axis can be minimized.
The eighth embodiment of the present application is characterized in that, in the first or second embodiment, the cathode has a plurality of electron beam emission regions formed by electric discharge machining.

By producing a cathode, for example, a LaB6 cathode, by electric discharge machining, a surface free from machining distortion can be obtained.
In the ninth embodiment of the present application, in the first or second embodiment, on the stage having the same height as the sample, a marker composed of two lines and spaces is located at a position corresponding to the plurality of beams. It is characterized by being arranged in plural.

    According to this embodiment, the marker corresponding to all the beams can be scanned simultaneously under the condition that the one marker corresponding to one beam is scanned, and scanning in two directions, for example, the x direction and the y direction can be performed simultaneously. If performed once, the beam dimensions in the x-direction and y-direction of all the beams can be measured. Therefore, all the beams can be evaluated in the time for evaluating one beam, and the beam adjustment time is shortened. can do.

    The tenth embodiment of the present application is characterized in that in the first or second embodiment, the evaluation is performed while continuously moving the sample stage in the uniaxial direction, and the evaluation regions of adjacent beams include an overlapping region. To do.

According to this embodiment, it is possible to reduce the probability that a defect is overlooked in the vicinity of the boundary of the evaluation area or a false defect occurs.
The eleventh embodiment of the present application is characterized in that, in the first or second embodiment, the thermionic emission cathode operates under a space charge limiting condition, and the shot noise reduction coefficient is 0.5 or less. To do.

    By operating the cathode under the space charge limiting condition, the shot noise can be reduced, and therefore a good evaluation of the S / N ratio can be performed with a small current.

    The twelfth embodiment of the present application is the wafer according to the first embodiment, in which the sample has a defective chip in the peripheral portion, and the discharge between the sample and the objective lens is generated in the defective chip region in the peripheral portion of the wafer. It has the function of examining conditions that do not occur.

    Since the defective chip is not used as a product, there is no problem even if it is destroyed. Therefore, it is possible to reliably prevent discharge by grasping the conditions that do not cause discharge by using these defective chip regions.

    The thirteenth embodiment of the present application has a function of detecting a defect from a difference between two images from which the same image should be obtained in the first or second embodiment, and whether or not the defect is a killer defect. It is characterized by having a function of judging.

According to this embodiment, it is possible to quickly and efficiently determine whether a defect is a killer defect or a non-killer defect.
The fourteenth embodiment of the present application is characterized in that, in the first or second embodiment, anodes that are insulated from each other corresponding to the plurality of beams are provided behind the microchannel plate.

    By configuring the detector as described above, the detector can be reduced in size, and thus the detection optical system can be reduced in size. In addition, since the rise and fall times of the detector are as short as 150 ps or 55 ps, for example, high-speed scanning can be performed.

The fifteenth embodiment of the present application is characterized in that, in the second embodiment, the deflection amount of the electromagnetic deflector of the second stage deflector is approximately twice the deflection amount of the electrostatic deflector. .
In the EXB deflector, since the deflection amount of the electrostatic deflector and the deflection amount of the electromagnetic deflector have the same absolute value and the deflection directions are opposite to each other, the deflection chromatic aberration caused by the EXB deflector is almost zero by the above conditions. Can be.

    The sixteenth embodiment of the present application is characterized in that, in device manufacturing, a wafer in the middle of a process is evaluated using the electron beam apparatus of the first to fifteenth embodiments.

    According to this embodiment, it is possible to manufacture a device with a high yield having the advantages of the electron beam apparatus of the first to fifteenth embodiments.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is an explanatory diagram of an electron beam apparatus according to an embodiment of the present invention. In the figure, the electron gun comprises a thermionic emission cathode 1 having a plurality of electron beam emission regions, a heater 2, a support fitting 3, a Wehnelt 4 and an anode 5. This electron gun operates under a space charge limited condition, and it has been confirmed that the shot noise is 1/5 or less of that in the temperature limited condition, and the operating temperature of the cathode 1 is determined. The cathode 1 and the Wehnelt 4 are processed so as to have a plurality of electron beam emission regions. The plurality of electron beams emitted from the electron gun are expanded in the emission direction by the condenser lens 6 and focused by the second-stage condenser lens 7 to irradiate the aperture plate 8 having a plurality of openings. At this time, a plurality of electron beams from the cathode 1 are allowed to pass through corresponding openings of the aperture plate 8. The aperture plate 8 is provided with an aperture position so that the beam intervals projected onto the scanning direction axis are all equal. The excitation conditions for the condenser lens 7 are determined so that the electron beam exiting the aperture forms a crossover at the NA aperture 9. The electron beam that has exited the aperture is reduced by the reduction lens 10 and the objective lens 14 to form a plurality of probe electron images on the sample 15. The scanning deflectors 11 and 12 scan in the X direction, and the entire surface of the sample 15 is evaluated by continuously moving the sample stage, that is, the stage 16 in the Y direction. A plurality of groups of secondary electrons emitted from each scanning point of the sample 15 are focused into narrow beams by the objective lens 14 and deflected to the right in the figure by the electromagnetic deflector 13 to be formed on a single Si substrate. Each beam is independently detected without mutual crosstalk by a detector 24 including a PIN diode group inserted therein, amplified, converted into a digital signal, and then input to the two-dimensional image forming apparatus 27.

  A scanning signal is input from the scanning power supply 26 to the two-dimensional image forming apparatus 27, and a plurality of SEM images are created. Evaluation such as defect inspection from the SEM image is controlled by the CPU 28, and evaluation such as defect inspection is performed and displayed on the display unit. A series of controls when evaluation is performed by the CPU 28 is performed by an operator console 29 to interface with an operator. The SEM image is stored in the image memory 30, and an image created from the design data is supplied from the image memory 31 as necessary.

    As shown in FIG. 2, the secondary electron detector 24 is formed by forming a plurality of PIN diodes around an optical axis on a single substrate, for example, a Si substrate. The arrangement of 6 corresponds to the opening position of the opening plate 8. In FIG. 2, 24-7 is a bonding pad, 24-8 is an aluminum wiring, 24-9 is a SiO2 passivation, and 24-10 is a common ground. A front surface of the secondary electron detector 24 has a multi-aperture plate 23 provided with openings corresponding to the positions of the electrosensitive surfaces 24-1 to 24-6 to prevent mutual crosstalk. Further, the detector position is adjusted so that the output is maximized by the R-θ stage 25.

    Further, instead of the PIN diode, as shown in FIG. 3, a plurality of independent MCP groups 24a-1 to 24a-6 are formed in the MCP substrate 24a, and a plurality of anodes 24b- You may use detector 24 'which combined 1-24b-6.

  The stage 16 is moved by causing the laser from the laser oscillator 21 to enter the movable mirror 19 attached to the stage and the fixed mirror 18 attached to the outside of the objective lens 14, and the reflected beam from these movable mirror 19 and fixed mirror 18. By detecting the interference light with a receiver, measurement, that is, the XY coordinate position of the stage is calculated. For this reason, even if the position of the objective lens 14 fluctuates due to vibration or thermal expansion, the fluctuation is measured, so that the image is not affected.

  Since a negative high voltage is applied to the sample 15, there is a possibility that discharge occurs between the sample 15 and the objective lens. Before the discharge occurs, corona discharge light is emitted as a precursor phenomenon, or an abnormal current flows through the sample. For this reason, this precursor phenomenon is detected by detecting light emission with the photomultiplier 32 or detecting an abnormal current with an ammeter (not shown). By adjusting, local destruction of the sample due to discharge can be prevented.

  FIG. 4 shows an embodiment of the cathode 1 and the Wehnelt 4 of the present invention. A plurality of protrusions 3-5 are formed on the cathode 1, and an electron beam is emitted from the tip 4-5. At this time, if there is a difference in the Z direction distance between the tip 4-5 and the Wehnelt hole 7-5 between the emitters, the intensity of the emitted electrons is different, and a uniform beam intensity cannot be obtained. Therefore, a function for adjusting the parallelism between the Wehnelt surface 6-5 and the surface formed by the tip 4-5 of the plurality of emitters is provided. In other words, the cathode 1 is supported on an insulating base plate 11-5 disposed in a cylindrical support 8-5, and a plurality of screws 1 are screwed to the bottom plate 9-5 of the support 8-5. It is mounted on the screws 12a-5 and 12b-5. A plate spring 14-5 is arranged between the base plate 11-5 and a spring receiver 15-5 fixed to the support 8-5, and the base plate 11-5 is always adjusted by adjusting screws 12a-5 and 12b. It is pressed by -5. By adjusting the screws 12a-5 and 12b-5, the parallelism between the surface formed by the tip 4-5 of the emitter and the surface of the Wehnelt 4 can be adjusted. The screws 13a-5 and 13b-5 are screws for adjusting the centering between the tip 4-5 of the emitter and the opening 7-5. In the figure, 18-5 is a heater for heating, and 17-5 is a metal fitting for supporting the heater.

FIG. 5 is a view of the cathode 1 as viewed from below. If the number of emitters 12-6 is an even number, the symmetry is good, and astigmatism is not generated. Further, if all the distances Lx between adjacent emitters projected in the X-axis direction (scanning direction) of each emitter 12-6 are made equal, a useless area is not scanned. In the figure, when the angle θ formed by the line connecting the target emitters through the optical axis O and the X axis is set to an appropriate value, the difference between the maximum value L ₁ and the minimum value L ₂ between the emitters can be minimized. There is. When the maximum value L ₁ of the adjacent values of the emitter-to-emitter spacing is equal at four locations, the difference between L ₁ and L ₂ is the smallest. FIG. 5B is an enlarged view of the tip of one emitter 12-6, and an emission region 13-6 that can emit a strong electron beam is formed at the tip.

  6 and 7 are diagrams for explaining a processing method of the cathode 1. 6 is an overall view of the cathode tip, FIG. 7A is a plan view of an electrode for forming a single emitter protrusion by electric discharge machining, and FIG. 7B is a side view of the electrode. is there. If a small hole of 100 μmφ shown in e-6 is provided in the center of the electrode a-6, a plane portion emitting a strong beam shown in 13-6 in FIG. 5 is formed at the tip of the emitter. When an electrode having a c-6 hole having a conical shape is used, a conical protrusion corresponding to the apex angle can be processed. In addition, in FIG. 7, b-6 shows the end surface of an electrode and d-6 shows the attachment part of an electrode.

  FIG. 8 is a diagram showing a relationship between a beam and a marker for adjusting a plurality of beams of the primary optical system. Markers 21-5 and 22 comprising a line and space marker parallel to the X axis and a line and space marker parallel to the Y axis in the same arrangement as a plurality of primary beams (9 beams in the figure) on the same plane as the sample. -5, ... 2n-5 are arranged close to each other. All beams can scan all markers simultaneously, with one beam scanning a specific marker. If the scanning in the X direction and the scanning in the Y direction are performed once for one beam, all the beam dimensions in the X direction and the beam dimension in the Y direction can be measured. Therefore, since all the beams can be evaluated in the time for evaluating one beam, the beam adjustment time can be shortened.

  FIG. 9 is a diagram for explaining how to handle evaluation at the boundary between the fields of view SA1 to SA9 scanned by each beam when pattern evaluation such as defect inspection is performed. In the figure, the sample stage is continuously moved in the Y direction, and the evaluation is performed by simultaneously scanning a plurality of beams EB1 to EB9 in the X direction. As shown in the figure, when a plurality of beam positions are projected on the X-axis, the interval between adjacent beams, which is equally spaced, is Lx, and the scanning width of each beam is Lx + Δ. That is, an overlap scanning region is generated by Δ in each scanning width. As shown in FIG. 6B, between the width Δ, the pattern Pt-1 connected to the right visual field SA2 and the pattern Pt-2 connected from the left visual field SA1 are mixed. In this case, the boundary Bol indicated by the dotted line in FIG. 5B is considered, and the pattern on the right side of Bol is evaluated in the right visual field, and the pattern on the left side of Bol is evaluated in the left visual field. That is, the image data processing is performed by using the image data from the detector corresponding to the beam EB2 in the area on the right side of the boundary line Bol and using the image data from the detector corresponding to the beam EB1 in the area on the left side. Based on this, evaluation such as defect inspection is performed. As a result, the probability that a defect was missed near the boundary of the visual field or a fake defect occurred was reduced.

  FIG. 10 shows the arrangement of devices in one wafer W. A plurality of rectangular chips 31-12 are taken from the circular wafer W, but there are defective chips as indicated by reference numerals 32-12 and 33-12 in the peripheral region. Of course, all the processes are performed on the chip having no defect shown in 31-12. All processes are performed in the same manner for the defective chips indicated by 32-12 and 33-12. Therefore, when examining conditions under which discharge occurs between the wafer W and the objective lens 14 during evaluation or conditions under which discharge does not occur, if the conditions are examined in the area within the defective chip 32-12, 33-12, even if the discharge occurs. Even if you wake up and destroy the pattern, it is not a chip that will eventually yield good products, so it will not degrade the yield.

  FIG. 11 is a diagram illustrating an evaluation example in the case of identifying whether a defect is a killer defect or not a killer defect in defect inspection. This example shows a case where the conductive material in the wiring pattern is detected as a defect candidate. As shown in FIGS. 5A and 5B, the defects Ptn-1 and Pta-1 that do not short-circuit the wiring patterns Ptn do not become killer defects. However, as shown in FIG. 5C, the defect Pta-2 that straddles the wiring pattern Ptn becomes a killer defect. As described above, when evaluating the defect inspection, it is possible to provide a function of identifying whether the defect is a killer defect by examining the relationship between the defect candidate pattern and the original pattern.

FIG. 12 is an explanatory diagram of the second embodiment of the present invention.
The electron gun is composed of a LaB6 cathode 91, a Wehnelt 92, and an anode 93, and operates in a space charge limited region. The NA of the electron beam emitted from the electron gun is determined by the opening 95, the crossover is reduced by the condenser lens 94 and the objective lens 99, and the sample 100 is irradiated. Scanning is performed on the sample by deflecting and scanning the beam in two stages of electrostatic deflectors 96 and 97. In parallel with this, the following DC signals are given to the electrostatic deflectors 96 and 97 and the electromagnetic deflector 98 for secondary electron detection. That is, the primary beam is deflected by the angle γ by the electrostatic deflector 96, further deflected by the angle α by the electrostatic deflector 97 and the electromagnetic deflector 98, and the principal ray intersects the optical axis in the vicinity of the objective lens 99. By doing so, the aberration generated in the objective lens 99 is reduced. The deflection directions of the electromagnetic deflector 98 and the electrostatic deflector 97 are opposite to each other. Therefore, the deflection amount of the deflector 98−the deflection amount of the deflector 97 = α, and the deflection amount of the secondary electrons is deflected. The deflection amount of the device 98 + the deflection amount of the deflector 97 = β. Regarding the deflection chromatic aberration, if the deflection chromatic aberration on the sample by the deflector 96 + the deflection chromatic aberration on the sample by the deflector 97 = (deflection chromatic aberration by the deflector 98) × 2, the deflection chromatic aberration on the sample is minimum. Become. This is because the deflection chromatic aberration due to the electromagnetic deflector is half of the chromatic aberration of the electrostatic deflector, and the deflection directions are opposite to each other. In general, a model including three deflectors 96, 97, and 98 and an objective lens 99 is created, and it is preferable that β be 5 to 10 ° or more under the condition that the sum of all aberrations is minimized by simulation.

In the second embodiment, an example in which an electron gun that generates a single beam is used has been described. However, a plurality of beams can be used as in the previous embodiment. That is, a cathode that generates a plurality of beams may be used, or a plurality of beams may be formed by irradiating a single beam to an aperture plate having a plurality of openings. In this case, the detector shown in FIGS. 2 and 3 can be used as in the previous embodiment.
〔The invention's effect〕

As described above, according to the present invention, the following effects can be obtained.
1) Since it is possible to detect a discharge precursor phenomenon that occurs between the sample and the objective lens and to avoid the rise of the discharge, there is no possibility of damaging the irradiation region of the sample or the objective lens.
2) The difference in the amount of electron emission from the plurality of emitters is small, and the beam current or beam diameter between the plurality of beams can be made uniform.
3) Since the defective chip is never used as a product, there is no problem even if it is destroyed. Therefore, it is possible to reliably prevent discharge by grasping the conditions that do not cause discharge by using these defective chip regions.

It is the schematic which shows one Embodiment of the evaluation apparatus using the electron beam apparatus of this invention. FIG. 2A is a plan view of the secondary electron detector shown in FIG. 1, and FIG. 2B is a cross-sectional view taken along line BB of FIG. . 2A and 2B are diagrams showing another embodiment of the secondary electron detector shown in FIG. 1, wherein FIG. 1A is a plan view, and FIG. 2B is a cross-sectional view taken along line BB in FIG. is there. It is sectional drawing explaining the alignment mechanism of the emitter of a cathode applicable to the electron beam apparatus of this invention, and the opening of a Wehnelt. FIG. 2A is a plan view of the cathode tip of an electron gun applicable to the electron beam apparatus of the present invention, and FIG. 3B is a side view of the emitter of the cathode. FIG. 6 is a side view of the cathode shown in FIG. 5. FIGS. 5A and 5B are diagrams showing electrodes for electric discharge machining of the cathode emitter shown in FIGS. 5 and 6, wherein FIG. 5A is a plan view and FIG. 5B is a side view. It is a figure which shows the relationship between the beam and marker for evaluating the several beam of the primary optical system in the electron beam apparatus of this invention. It is a figure for demonstrating the data processing in the boundary area | region of the visual field at the time of performing pattern evaluations, such as defect inspection. It is a top view which shows arrangement | positioning of the device on one wafer. It is a figure for demonstrating identification of the killer defect in a defect inspection performed using the electron beam apparatus of this invention, and a non-killer defect. It is the schematic which shows the 2nd Example of this invention.

Explanation of symbols

1, 91: cathode 4, 92: Wehnelt 5, 93: anode 6, 7, 94: condenser lens 8: aperture plate 10: reduction lenses 11, 12, 96, 97: electrostatic deflectors 13, 98: electromagnetic deflection Instruments 14, 99: Objective lenses 15, 100: Sample 18: Fixed mirror 19: Moving mirror 21: Laser oscillator 23: Multi-aperture plate 24, 103: Secondary electron detectors 24-1 to 24-6: Electrosensitive surface 24a -1 to 24a-6: MCP
24b-3, 24b-6: Anode 27: Image forming apparatus 28: CPU

Claims (6)

An electron beam apparatus that irradiates a sample with an electron beam emitted from an electron gun and evaluates the sample,
The sample is adapted to apply a negative high voltage, and has a measuring device for detecting a precursor phenomenon of the discharge between the sample and the objective lens, and the voltage applied to the sample from the signal of the measuring device or An electron beam apparatus having a function of adjusting a current to a discharge voltage or lower than the current.     The electron beam apparatus according to claim 1, wherein the measuring device is made of a photomultiplier that detects corona discharge.     The electron beam apparatus according to claim 1, wherein the measuring device includes an ammeter that detects an abnormal current. A primary optical system having an electron gun that emits an electron beam and irradiating the sample surface to be inspected with the electron beam from the electron gun;
A secondary optical system for making secondary electrons emitted from the sample incident on a secondary electron detector;
The electron gun includes a cathode having a plurality of protrusions, a Wehnelt having holes provided corresponding to the protrusions of the cathode, a surface formed by tips of the plurality of protrusions of the cathode, and a surface of the Wehnelt And an adjusting mechanism for adjusting the parallelism of the electron beam apparatus.     The electron beam apparatus according to claim 4, wherein the adjustment mechanism includes a screw and a spring.     A defect inspection method in which an electron beam emitted from an electron gun is applied to a sample and the sample is evaluated, wherein the defect is characterized by examining conditions under which the sample causes discharge in a region within a defective chip in the sample Inspection method.

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