JP2005098703A - Electron beam measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily detect as to whether light irradiation is carried out appropriately, and to appropriately irradiate a prescribed portion on an object to be measured with the light. <P>SOLUTION: An electron beam measurement apparatus is provided with an electron gun 16 which emits an electron beam; electronic lens system components 18, 24 and 30 which focus the electron beam onto a prescribed focal point; a measurement object support section 14 on which the object to be measured 12 can be mounted; an optical microscope 48 which detects an optical image about the object to be measured 12 in a prescribed measurement region; a displacement gauge 44 which irradiates the object to be measured 12 in the measurement region with the light and receives reflection light being reflected by the object to be measured 12; and a focus control section 56 which detects the amount of deviation between positions of the object to be measured 12 and the focal point of the electronic lens system components 18, 24 and 30, based on the light received by the displacement gauge 44. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electron beam measurement apparatus that performs a predetermined measurement process on a measurement object using an electron beam.
[0002]
[Prior art]
Conventionally, for example, a measurement target such as a GMR (Giant Magneto Resistive) head element is observed with an optical microscope, and based on the observed image, the length of a predetermined portion such as the width of a writing magnetic pole, the width of a reading sensor, etc. An optical measuring apparatus for measuring the length is known. In recent years, patterns such as magnetic poles in the GMR head element have been miniaturized, and it has become impossible to measure the length with an optical measuring device. Therefore, an electron beam measuring apparatus that performs length measurement using an electron beam has attracted attention.
[0003]
In the electron beam measuring apparatus, it is necessary to focus the electron beam on a predetermined portion to be measured. As a method of focusing the electron beam, the measurement target is positioned at a predetermined place where the electron beam is irradiated, and a predetermined portion of the measurement target irradiated with the electron beam is irradiated with laser light. Of adjusting the height of the measurement object so that the position where the reflected light is received becomes the position where the reflected light is received when the previously detected electron beam is in focus It has been known.
[0004]
[Problems to be solved by the invention]
In the conventional electron beam measuring apparatus described above, in order to properly focus the electron beam on a predetermined portion of the measurement target, the measurement target is positioned at a position where the electron beam is irradiated, and the focus of the measurement target is at that position. It is necessary to appropriately irradiate a laser beam onto a predetermined portion to be matched, for example, a pattern to be measured. However, since the laser beam is irradiated in a vacuum, it cannot be easily detected whether or not the laser beam is properly irradiated, and the position where the laser beam is irradiated is adjusted easily and appropriately. The problem of being unable to do so arises.
[0005]
In particular, when the predetermined portion to be focused on in the measurement target is a small piece or a thin rod shape, there is a high possibility that the laser light is irradiated and scattered on the edge of the portion, and the position of the reflected light is accurately determined. There is a high possibility that a problem that it cannot be detected and focusing cannot be performed properly will occur. For this reason, it is required to be able to adjust the position where the laser beam is irradiated in more detail. Further, in the electron beam measuring apparatus, it is required to shorten the time required for the length measurement process and to reduce the apparatus size.
Further, for example, similar problems occur in other electron beam measuring apparatuses such as an electron beam tester that performs electrical measurement on a measurement target.
[0006]
Accordingly, an object of the present invention is to provide an electron beam measuring apparatus that can solve the above-described problems. This object is achieved by a combination of features described in the independent claims. The dependent claims define further advantageous specific examples of the present invention.
[0007]
[Means for Solving the Problems]
To achieve the above object, an electron beam measuring apparatus according to a first embodiment of the present invention is an electron beam measuring apparatus that performs a predetermined measurement on a measurement object using an electron beam, and irradiates the electron beam. An electron gun, a deflecting unit that deflects the electron beam, an electron lens system that connects the electron beam to a predetermined focal point, a detector that detects electrons scattered due to the electron beam, and the deflecting unit scan the electron beam. A scanning control unit, a measurement target holding unit on which a measurement target can be placed, an optical microscope that detects an image of light on the measurement target in a predetermined observation region, and an irradiation that irradiates the measurement target in the observation region with light Position shift amount for detecting the shift amount between the position of the measurement target and the focus position of the electron lens system based on the system, the light receiving system that receives the reflected light reflected by the measurement target, and the light received by the light receiving system Detector and A focusing unit for focusing the electronic lens on the measurement target based on the shift amount, and a measurement unit for performing a predetermined measurement process when the focusing of the electronic lens system is focused on the measurement target by the focusing unit. It is characterized by having.
[0008]
The measuring unit further includes a length measuring unit for measuring a predetermined portion of the measurement target based on a change state of electrons sequentially detected by the detector when the scanning control unit scans the electron beam. It may be. An irradiation position detection unit that detects an irradiation position of light emitted from a light emitting unit in an image detected by an optical microscope, and an irradiation position adjustment unit that adjusts the irradiation position to a predetermined reference portion of a measurement target, and a positional shift The amount detection unit may detect the amount of deviation between the position of the measurement target and the focus position of the electron lens system based on the light received by the light receiving system in a state where the irradiation position is aligned with the reference portion. Good. The focusing unit may focus by moving the measurement target. You may make it further have a display part which displays the image detected on the optical microscope. You may make it have an adjustment instruction | indication reception part which receives the instruction | indication which adjusts an irradiation position from a user, and an irradiation position adjustment part which adjusts the irradiation position in a measuring object based on an instruction | indication.
[0009]
The irradiation system emits light and emits light emitted by the light emitting unit to the measurement target in the observation area and guides the reflected light reflected by the measurement target to be detected by the optical microscope. The light receiving system includes a light receiving unit that receives light, and a light receiving side optical unit that guides a part of the reflected light to the optical microscope and guides a part of the reflected light to the light receiving unit. May be.
[0010]
The irradiation-side optical part and the light-receiving-side optical part may each have a partially-passing and partially-reflecting surface that transmits a part of the light and reflects a part of the light. The partially passing partially reflecting surface of the irradiation side optical part and the partially passing partially reflecting surface of the light receiving side optical part may be on the same plane. You may make it equip the irradiation side optical part and the light-receiving side optical part in the position shifted | deviated from the optical axis of an optical microscope, and its vicinity. The irradiation-side optical part and the light-receiving-side optical part may be formed integrally, and may have a partially-passing and partially-reflecting surface that transmits a part of the light and reflects a part of the light.
[0011]
You may make it an irradiation side optical part and a light reception side optical part have an opening in the optical axis of an optical microscope, and its vicinity. The light emitting unit and the light receiving unit may be arranged at positions deviated from and near the optical axis center connecting the optical axis center of the optical microscope and the optical axis center of the electron lens system.
The above summary of the invention does not enumerate all necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the solution of the invention.
FIG. 1 is a diagram showing a configuration of an electron beam measurement apparatus according to the first embodiment of the present invention. This electron beam measurement apparatus is an electron beam measurement apparatus that measures a predetermined portion of a GMR head element as an example of a measurement target, for example. It is assumed that the X axis, the Y axis, and the Z axis are taken as shown in the figure.
[0013]
Here, the measurement target may be not only a semiconductor component composed of an active element such as an IC (Integrated Circuit) or an LSI (Large-Scale Integrated circuit), but also a component such as a passive element or various sensors. Furthermore, the component may be a component that is combined into a single package, or a component such as a breadboard that realizes a predetermined function by mounting these components on a printed circuit board. Further, it may be a component that may be damaged by a magnetic field, such as a GMR head element.
[0014]
The electron beam measuring apparatus 100 includes an electron beam column 102, a vacuum chamber 104, an amplifier 38, an analog / digital converter (A / D converter) 40, a storage unit 50, a control unit 52, and an analysis voltage. As an example of the application unit 42, a receiving unit 70 as an example of an adjustment instruction receiving unit, a keyboard 72, a mouse 74, a display device 76 as an example of a display unit, an optical microscope 48, and an irradiation system and a light receiving system. Displacement meter 44 and half mirror 46. The electron beam column 102 includes an electron gun 16, a deflection plate 20, a chopping aperture 22, a deflector 26 as an example of a deflection unit, an astigmatism correction lens 28, and an electron lens 18 as an example of an electron lens system. , Electron lens 24 and objective lens 30, energy filter 34, and detector 36. In the present embodiment, the irradiation side optical unit and the light receiving side optical unit referred to in the claims are configured by a half mirror 44. Here, each of the electron lens 18, the deflection plate 20, the electron lens 24, the deflector 26, the astigmatism correction lens 28, and the lens 30 may use either a magnetic field or an electric field. Good. In the present embodiment, since a part that is damaged by a magnetic field such as a GMR head element is a measurement target, the lens 30, the electron lens 18, the deflection plate 20, the electron lens 24, the deflector 26, and astigmatism correction. Each of the lenses 28 preferably uses an electric field.
[0015]
The vacuum chamber 104 includes a stage 14 as an example of a measurement object holding unit. The stage 14 holds the measurement object 12 in a detachable manner. The stage 14 can move in the X-axis direction, the Y-axis direction, and the Z-axis direction in the vacuum chamber 104. In this embodiment, the stage 14 detachably holds a sample substrate having a plurality of measurement objects 12. Here, in this embodiment, the sample substrate is a so-called bar (BAR) having a plurality of measurement objects 12 cut out from a wafer on which the plurality of measurement objects 12 are formed.
[0016]
FIG. 2 is a diagram showing a partial configuration of the electron beam measuring apparatus according to one embodiment of the present invention. 2A is a diagram in which a part of the electron beam measuring device is cut along the XY plane, and FIG. 2B is a diagram in which a part of the electron beam measuring device is cut along the XZ plane. is there. As shown in FIG. 2B, the optical microscope 48 includes a CCD camera 48a that captures an image connected to a light receiving surface, and an optical lens system 48b that connects an image in a predetermined observation field to the light receiving surface of the CCD camera 48a. Have The CCD camera 48 a inputs the captured image information to the control unit 52. In the present embodiment, the optical microscope 48 captures an image within the observation field and inputs it to the control unit 52 when performing global alignment.
[0017]
The half mirror 46 has a partially-passing partially reflecting surface that allows a part of the irradiated light to pass and reflects a part of the light. In the present embodiment, the half mirror 46 is a side on which an object to be detected by the optical lens system 48b, for example, a measurement object is to be placed, and at least in an optical path through which light reaching the CCD camera 48a from the object to be detected passes. It is arranged so as to cross a part. In the present embodiment, as shown in FIG. 2B, the half mirror 46 is arranged with an angle of approximately 45 degrees between planes parallel to the XY plane.
[0018]
The displacement meter 44 detects information for specifying the position of the object in the observation visual field on the Z axis. In the present embodiment, the displacement meter 44 includes a light emitting unit 44a that emits light, for example, laser light, and a light receiving unit 44b that receives the light. The light emitting unit 44a and the light receiving unit 44b are disposed at positions shifted between and near the optical axis center connecting the optical axis center of the optical microscope 48 and the optical axis center of the electron lens system 30 and the like. In the present embodiment, the light emitting unit 44 a and the light receiving unit 44 b are arranged on the opposite side of the optical axis center of the electron lens system 30 with respect to the optical axis center of the optical microscope 48. Therefore, since there is no configuration of the light emitting unit 44a and the light receiving unit 44b between the optical axis center of the electron lens 30 and the like and the optical axis center of the optical microscope 48, the interval between them can be shortened. Thereby, the moving distance of the stage 14 can be suppressed, and errors occurring in the height direction when the stage 14 is moved from below the optical axis of the electron lens 30 or the like to the optical axis of the optical microscope 48 can be suppressed. The size of the vacuum chamber 104 can be reduced. In the present embodiment, the light emitting unit 44a emits light in a direction having a slight angle with the X axis in a plane parallel to the XY plane.
[0019]
The light emitted from the light emitting unit 44a is guided to the object in the observation region by the half mirror 46, and a part of the reflected light reflected by the object passes through the half mirror 46 so that it can be detected by the optical microscope 48. In other words, it is guided to the light receiving surface of the CCD camera 48a. A part of the reflected light reflected by the object is reflected by the half mirror 46 and guided to the light receiving unit 44b.
[0020]
According to this configuration, when the position of the target in the observation region on the Z-axis changes, the position on the Y-axis where the light emitted from the light emitting unit 44a reflects changes. For this reason, the position where the light receiving unit 44b receives the reflected light is different, and the position of the target on the Z axis can be detected based on the position where the reflected light is received. In addition, since the height position of the measurement target is detected near the optical microscope as described above, the optical path length from the light emitting portion to the light receiving portion can be suppressed, and the height position can be detected with high accuracy and high resolution. can do.
[0021]
Returning to FIG. 1, the electron beam EB is irradiated from the electron gun 16 in the electron beam measuring apparatus. The electron beam EB irradiated from the electron gun 16 is introduced between the deflection plates 20 via the electron lens 18. The deflecting plate 20 deflects the electron beam EB so that the electron beam EB passes through an opening of the chopping aperture 22 for a predetermined time so that the electron beam EB is pulsed. The pulsed electron beam is irradiated to the stage 14 side in the vacuum chamber 104 through the electron lens 24, the deflector 26, the astigmatism correction lens 28, and the objective lens 30.
[0022]
The deflector 26 deflects the electron beam EB and changes the position where the electron beam is irradiated. The astigmatism correction lens 28 corrects astigmatism generated in the electron beam EB. Secondary electrons generated by irradiating the measurement object 12 or the reference substrate 13 with the electron beam EB are sequentially detected by the detector 36 via the energy filter 34. The detector 36 inputs the detected amount of secondary electrons (secondary electron amount) to the amplifier 38.
[0023]
The amplifier 38 amplifies the input secondary electron amount and inputs it to the A / D converter 40. The A / D converter 40 converts the amount of secondary electrons input from the amplifier 38 into a digital signal and inputs the digital signal to the control unit 52. The analysis voltage application unit 42 applies an analysis voltage to the energy filter 34 based on the control of the control unit 52. The storage unit 50 stores a correspondence relationship between time and length in scanning of the electron beam, for example, a coefficient used for calculation for obtaining the length from the time in scanning. The storage unit 50 also has information (reference height) regarding the position detected by the displacement meter 44 when the focused surfaces of the electron lens systems 18, 24 and 30 are positioned in the observation region of the optical microscope 48. Information).
[0024]
The control unit 52 includes an alignment control unit 54 as an example of an irradiation position detection unit and an irradiation position adjustment unit, a focus control unit 56 as an example of a focusing unit, and a length measurement as an example of a length measurement unit and a scanning control unit. A control unit 58, a display control unit 60, a stage control unit 62, and a calibration control unit 64 are provided. The calibration control unit 64 causes the stage control unit 62 to adjust the substrate to be focused, such as the electron lens system 30 mounted on the stage 14, to a plurality of heights, and at each height, electronically adjusts a predetermined pattern on the substrate. The beam is scanned to detect the change state of the amount of secondary electrons detected by the detector 36, and the height of the substrate when the change rate of the secondary electron amount is the largest is the focus of the electron lens system on the substrate. It is detected as the height of the substrate when there is. Next, the calibration control unit 64 adjusts the substrate to a height at which the electron lens system is in focus, moves the substrate into the observation region of the optical microscope 48, causes the displacement meter 44 to irradiate the substrate with light, and reflects it. Light is received and information on the position of the received reflected light is detected. The calibration control unit 64 stores the position information in the storage unit 50 as reference height information for specifying the height of the substrate when the electronic lens system 30 or the like is in focus.
[0025]
Based on the image input from the optical microscope 48, the alignment control unit 54 performs adjustment, that is, global alignment so that the measurement object 12 can be moved to a range in which the electron beam from the electron gun 16 can be irradiated. . In the present embodiment, adjustment is performed so that each measurement object 12 in the bar is aligned with the coordinate system of the stage 14. Further, the alignment control unit 54 detects the irradiation position on the measurement target 12 of the light irradiated from the displacement meter 44 based on the image input from the optical microscope 48, and determines the irradiation position as the Z axis of the measurement target 12. The stage controller 62 moves the stage 14 so that the height in the direction matches the reference position to be measured. Accordingly, the reference position can be appropriately irradiated with light from the displacement meter 44, and the position of the reference position in the Z-axis direction can be detected with high accuracy. For this reason, the focus of the electron lens system 30 and the like can be appropriately adjusted to the reference position.
[0026]
In addition, the alignment control unit 54 moves the stage 14 by the stage control unit 62 so that the light from the displacement meter 44 is irradiated to the position corresponding to the adjustment instruction received by the receiving unit 70. As a result, it is possible to appropriately irradiate light from the displacement meter 44 to a position according to the user's instruction, and to detect the position in the Z-axis direction of the position with high accuracy. For this reason, the focus of the electronic lens system 30 etc. can be appropriately adjusted to the position instructed by the user.
[0027]
In addition, after global alignment, the alignment control unit 54 causes the stage control unit 62 to move the measurement object 12 to a predetermined place where the electron beam can be irradiated, and then performs local alignment (fine alignment). That is, the alignment control unit 54 scans the electron beam on the measurement object 12 and forms a secondary electron image of the measurement object 12 based on the change state of the secondary electrons detected from the detector 36. Next, the alignment control unit 54 detects the amount of deviation in the X-axis direction, the amount of deviation in the Y-axis direction, the amount of rotation, and the like based on the secondary electron image, and based on these amounts, Make various adjustments. In the present embodiment, the alignment control unit 54 adjusts the position and direction in which the length measurement control unit 58 scans the electron beam with the deflector 26.
[0028]
The focus control unit 56 determines the position of the measurement target and the focus of the electronic lens system 30 based on the information on the position of the measurement target input from the displacement meter 44 and the reference height information stored in the storage unit 50. The position shift amount is detected, and the height of the measuring object 12 in the Z-axis direction is adjusted by the stage control unit 62 based on the shift amount. As a result, the height position of the measurement target can be adjusted to the focal position of the electron lens system 30 or the like. The length measurement control unit 58 scans the electron beam on the measurement object 12 by the deflector 26 and, on the basis of the change state of the secondary electrons sequentially detected from the detector 36, the electron is applied to a predetermined part of the measurement object 12. The time during which the beam is irradiated is detected, and the length corresponding to the detected time is detected based on the correspondence relationship stored in the storage unit 50.
[0029]
The display control unit 60 causes the display device 76 to display an image detected by the optical microscope 48. From this image, it is possible to grasp the irradiation position where the light from the displacement meter 44 is irradiated onto the measurement object 12. The display control unit 60 causes the display device 76 to display the length of the measurement target portion detected by the length measurement control unit 58. The stage control unit 62 controls the drive of the stage 14. For example, the stage control unit 62 moves the stage 14 so that the measurement target 12 placed on the stage 14 is positioned within the observation field of view of the optical microscope 48. The stage control unit 62 moves the stage 14 so that the measurement target 12 is located substantially at the center of the optical axis of the electron beam. The stage control unit 62 moves the stage 14 in the Z-axis direction. The accepting unit 70 accepts an instruction from the user using the keyboard 72 or the mouse 74. In the present embodiment, the accepting unit 70 accepts an instruction to adjust the position at which light from the displacement meter 44 is irradiated on the image displayed by the display device 76 from the user.
[0030]
Next, the operation of the electron beam measurement apparatus according to this embodiment will be described. First, the following calibration process is performed before the measurement process for measuring a predetermined portion of the measurement target. Here, it is assumed that a substrate for focusing the electron lens system 30 or the like is placed on the stage 14. In the calibration process, the calibration control unit 64 adjusts the substrate placed on the stage 14 to a plurality of heights, scans the electron beam in a predetermined pattern on the substrate at each height, and detects the detector 36. The change state of the secondary electron amount detected by the above is detected, the height when the rate of change of the secondary electron amount is large is detected, and the position where the substrate is in focus is detected. Next, the calibration control unit 64 adjusts the substrate to a height at which the substrate is in focus, moves the substrate into the observation region of the optical microscope 48, irradiates the substrate with light by the displacement meter 44, and receives reflected light. Information on the position of the received reflected light is detected. The calibration control unit 64 receives the position information and stores the position in the storage unit 50 as reference height information indicating the height of the substrate when the electronic lens system 30 or the like is in focus.
[0031]
Next, a measurement process for measuring a predetermined portion of the measurement target will be described. Here, it is assumed that a measurement object is placed on the stage 14. First, the alignment controller 54 moves the measurement object placed on the stage 14 by the stage controller 62 into the observation region of the optical microscope 48. At this position, the displacement meter 44 irradiates the measurement target 12 with light and receives reflected light from the measurement target 12. At the same time, the optical microscope 48 captures an image of the measurement target and outputs it to the alignment control unit 54. .
[0032]
Based on the image input from the optical microscope 48, the alignment control unit 54 performs global alignment so that the measuring object 12 can be moved to a range where the electron beam from the electron gun 16 can be irradiated. The alignment control unit 54 detects the irradiation position on the measurement target 12 of the light irradiated from the displacement meter 44 based on the image input from the optical microscope 48, and the irradiation position is the Z axis of the measurement target 12. The stage controller 62 moves the stage 14 so that the height in the direction matches the reference position to be measured.
[0033]
The displacement meter 44 irradiates the measurement target 12 with light, receives reflected light, detects information on the position of the received reflected light, and notifies the focus control unit 56 of the detected information. The focus control unit 56 focuses the electronic lens system 30 or the like on the measurement target 12 based on the position information of the measurement target input from the displacement meter 44 and the reference height information stored in the storage unit 50. The height of the measuring object 12 in the Z-axis direction is adjusted by the stage controller 62 so as to match. As a result, the focus of the electron lens system 30 or the like is adjusted to the measurement object 12 with high accuracy. At the same time, the alignment controller 54 causes the stage controller 62 to move the measurement object 12 to a predetermined position where the electron beam can be irradiated. Thus, since the global alignment and the height detection process of the measurement target can be performed in parallel, the time required for the process can be shortened.
[0034]
Thereafter, the alignment control unit 54 scans the measurement target 12 with an electron beam, and forms a secondary electron image of the measurement target 12 based on the change state of the secondary electrons detected from the detector 36. Next, the alignment control unit 54 detects the amount of deviation in the X-axis direction, the amount of deviation in the Y-axis direction, the amount of rotation, and the like based on the secondary electron image, and based on these amounts, The length measurement control unit 58 adjusts the position and scanning direction of the electron beam by the deflector 26.
[0035]
Next, the length measurement control unit 58 causes the deflector 26 to scan the electron beam on the measurement target 12, and based on the change state of the secondary electrons sequentially detected from the detector 36, a predetermined measurement of the measurement target 12 is performed. The time during which the portion is irradiated with the electron beam is detected, and the length corresponding to the detected time is detected based on the correspondence stored in the storage unit 50.
[0036]
FIG. 3 is a diagram illustrating another example of the half mirror according to the embodiment of the present invention. In this example, a half mirror 80 and a half mirror 82 are used in place of the single half mirror 46. Each of the half mirror 80 and the half mirror 82 has a partly passing partly reflecting surface that transmits part of the irradiated light and reflects part of the light. Further, the half mirror 80 and the half mirror 82 are arranged at positions removed from the optical axis of the optical lens system 48b and the vicinity thereof. Thereby, since the light passing through the optical axis of the optical lens system 48b and the vicinity thereof is not affected by the half mirror, it is possible to appropriately suppress the deterioration of the measurement target image in the observation region. For this reason, global alignment can be performed with high accuracy. In addition, the partially passing partially reflecting surfaces of the half mirror 80 and the half mirror 82 are arranged so as to be the same plane as the plane on which the partially passing partially reflecting surface of the half mirror 46 is placed.
[0037]
FIG. 4 is a diagram showing still another example of the half mirror according to the embodiment of the present invention. In this example, a half mirror 84 is used instead of the half mirror 46. The half mirror 84 has a partially-passing partially reflecting surface that allows a part of the irradiated light to pass and reflects a part of the light. The half mirror 84 has an opening at the optical axis of the optical lens system 48b and in the vicinity thereof. Thereby, since the light passing through the optical axis of the optical lens system 48b and the vicinity thereof is not affected by the half mirror 84, it is possible to appropriately suppress the deterioration of the image to be measured in the observation region. For this reason, global alignment can be performed with high accuracy. Further, the half mirror 84 is a single half mirror, so that it can be easily installed.
[0038]
The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the above-described embodiment, an example in which the partially-passing partially reflecting surfaces of the two half mirrors are located on the same plane is shown, but the present invention is not limited to this, and a part of these half mirrors Each of the passing partial reflection surfaces may be positioned on different planes, for example, may be positioned on planes parallel to each other. In the above embodiment, the displacement meter that detects the position in the Z-axis direction based on the position of the reflected light is used. However, the present invention is not limited to this, and the position in the Z-axis direction can be determined using light interference. A displacement meter to be detected may be used. In short, any displacement meter that detects the position in the Z-axis direction may be used.
[0039]
In the above-described embodiment, an example in which the present invention is applied to an electron beam measuring apparatus that measures a predetermined portion of a measurement target has been described. However, the present invention is an electron beam tester that performs electrical measurement of a measurement target. The present invention can be applied to other electron beam measuring apparatuses, and in short, can be applied to an electron beam measuring apparatus that detects the focal point of an electron lens.
[0040]
As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the description of the scope of claims that embodiments with such changes or improvements can be included in the technical scope of the present invention.
[0041]
【The invention's effect】
As is clear from the above description, according to the present invention, it is possible to easily detect whether or not the measurement object is appropriately irradiated with light. Moreover, it is possible to appropriately irradiate a predetermined portion on the measurement target with light.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an electron beam measurement apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram showing a partial configuration of an electron beam measurement apparatus according to an embodiment of the present invention.
FIG. 3 is a view showing another example of a half mirror according to an embodiment of the present invention.
FIG. 4 is a diagram showing still another example of a half mirror according to an embodiment of the present invention.
[Explanation of symbols]
12 Measurement target 14 Stage
16 electron gun 18 electron lens
20 Deflector plate 22 Chopping aperture
24 electron lens 26 deflector
28 Astigmatism correction lens 30 Objective lens
34 Energy filter 36 Detector
38 amplifier 40 A / D converter
42 Analysis voltage application section 44 Displacement meter
46 Half mirror 48 Optical microscope
50 storage unit 52 control unit
54 Alignment control unit 56 Focus control unit
58 Measurement controller 60 Display controller
62 Stage control unit 64 Calibration control unit
70 Reception Department 72 Keyboard
74 Mouse 76 Display device

Claims (13)

An electron beam measuring apparatus that performs a predetermined measurement on a measurement object using an electron beam,
An electron gun for irradiating the electron beam;
A deflection unit for deflecting the electron beam;
An electron lens system for connecting the electron beam to a predetermined focal point;
A detector for detecting electrons scattered due to the electron beam;
A scanning control unit that scans the electron beam with the deflection unit;
A measurement object holding unit capable of placing the measurement object;
An optical microscope for detecting an image by light of the measurement object in a predetermined observation region;
An irradiation system for irradiating the measurement object in the observation region with light;
A light receiving system that receives reflected light reflected by the measurement object;
Based on the light received by the light receiving system, a position shift amount detection unit that detects a shift amount between the position of the measurement object and the focus position of the electron lens system;
Based on the detected shift amount, a focusing unit that focuses the electronic lens on a measurement target;
An electron beam measurement apparatus, comprising: a measurement unit that performs a predetermined measurement process when the focusing unit is focused on the measurement target by the focusing unit. The measurement unit measures the length of a predetermined portion of the measurement target based on the change state of electrons sequentially detected by the detector when the scanning control unit scans the electron beam. The electron beam measuring apparatus according to claim 1, further comprising a unit. An irradiation position detection unit for detecting an irradiation position of the light irradiated by the light emitting unit in the image detected by the optical microscope;
An irradiation position adjusting unit that adjusts the irradiation position to a predetermined reference portion of the measurement object;
The positional deviation amount detection unit, based on the light received by the light receiving system in a state where the irradiation position is aligned with the reference portion, between the position of the measurement target and the position of the focus of the electron lens system The electron beam measuring apparatus according to claim 1, wherein a deviation amount is detected. The electron beam measuring apparatus according to claim 1, wherein the focusing unit focuses by moving the measurement object. The electron beam measurement apparatus according to claim 1, further comprising a display unit that displays the image detected by the optical microscope. An adjustment instruction receiving unit that receives an instruction to adjust the irradiation position from a user;
The electron beam measurement apparatus according to claim 5, further comprising an irradiation position adjustment unit that adjusts the irradiation position of the measurement target based on the instruction. The irradiation system is
A light emitting section for generating light;
An irradiation-side optical unit that guides the light emitted from the light-emitting unit to the measurement target in the observation region and guides the reflected light reflected by the measurement target to be detected by the optical microscope. ,
The light receiving system is
A light receiving portion for receiving light;
7. The electron according to claim 1, further comprising: a light receiving side optical unit that guides a part of the reflected light to the optical microscope and guides a part of the reflected light to the light receiving unit. Beam measuring device.   8. The irradiation-side optical part and the light-receiving-side optical part each have a partially-passing and partially-reflecting surface that transmits part of light and reflects part of light. An electron beam measuring apparatus according to 1. 9. The electron beam measurement according to claim 8, wherein the partially-passing partially reflecting surface of the irradiation-side light guide and the partially-passing partially reflecting surface of the light-receiving-side light guide are on the same plane. apparatus. 10. The electron beam measuring apparatus according to claim 8, wherein the irradiation side optical unit and the light receiving side optical unit are provided at positions deviated from the optical axis of the optical microscope and the vicinity thereof. 11. The irradiation-side optical part and the light-receiving-side optical part are formed integrally, and have a partly passing partly reflecting surface that allows part of light to pass and reflects part of light. The electron beam measuring apparatus according to claim 7. The electron beam measuring apparatus according to claim 11, wherein the irradiation side optical unit and the light receiving side optical unit have openings in the optical axis of the optical microscope and in the vicinity thereof. The light emitting unit and the light receiving unit are arranged at positions deviated from and near the optical axis center connecting the optical axis center of the optical microscope and the optical axis center of the electron lens system. The electron beam measuring apparatus according to claim 1.

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