JP5531515B2 - Charged particle beam irradiation apparatus and method for adjusting axis alignment of the apparatus - Google Patents

Description

  The present invention relates to an electronic apparatus such as a scanning electron microscope, an analysis apparatus / observation apparatus such as an electron beam microanalysis apparatus, an electron beam drawing apparatus, a semiconductor manufacturing apparatus such as an ion beam micromachining apparatus, and an industrial apparatus such as an electron beam processing machine. Charged particle beam irradiation apparatus for irradiating an object such as a sample with a charged particle beam in various apparatuses using charged particles such as a beam and an ion beam, and adjusting the optical axis of the charged particle beam in such a charged particle beam irradiation apparatus The present invention relates to an alignment adjustment method.

  For example, in an apparatus using charged particles such as an electron beam microanalyzer (EPMA), it is necessary to accurately irradiate an irradiation position on an observation object or workpiece with a charged particle beam emitted from a charged particle source. For example, in a general EPMA, an electron beam emitted from an electron gun is once converged by a converging lens, and an electron beam that diverges after convergence is passed through an aperture to be introduced into an objective lens by limiting the beam diameter. Then, the electron beam is focused by the objective lens and irradiated onto the sample surface (see, for example, Patent Document 1).

  In such a charged particle beam irradiation apparatus, in order to accurately irradiate a charged particle beam having a small diameter to a predetermined position on a sample or a workpiece, it is necessary to perform axial alignment of the charged particle beam with high accuracy. Conventionally, a deflector that deflects a charged particle beam by the action of a magnetic field or an electric field is generally used to perform axial alignment of the charged particle beam. For example, in Patent Documents 1 and 2 and the like, a two-stage deflector is provided between the charged particle source and the converging lens, that is, on the entrance side of the converging lens along the axial direction of the optical system. By deflecting the beam, the optical axis (orbit center) of the beam is aligned with the centers of the converging lens and the objective lens.

  By the way, in the charged particle beam irradiation apparatus described in Patent Document 3, a two-stage condenser lens (electromagnetic lens) whose focusing lens can be independently controlled for the purpose of adjusting the incident opening angle of the charged particle beam on the sample surface. It consists of In such a configuration, it is necessary to perform axial alignment so that the charged particle beam passes through the center of each of the two condenser lenses of the converging lens. Furthermore, it is necessary that the optical axis of the charged particle beam converged by the converging lens passes through the center of the objective lens.

  When the center of each of the two-stage condenser lenses constituting the converging lens and the center of the objective lens are aligned, the two-stage deflector provided on the entrance side of the converging lens as described above. Appropriate alignment is possible. When it is possible to move one of the two-stage condenser lenses with respect to the other, the machine is arranged so that the center of each of the two-stage condenser lenses and the center of the objective lens are in a straight line as described above. Adjustments can be made.

  However, when the two-stage condenser lens is integrated, specifically, for example, when the pole piece constituting the converging lens has an integral structure, the relative position of the two-stage condenser lens. The relationship cannot be adjusted. Therefore, the charged particle beam may not be allowed to pass through the center of each of the two-stage condenser lenses constituting the converging lens and the center of the objective lens.

  For example, if there is a misalignment between the center of the two-stage condenser lens constituting the converging lens and the charged particle beam, the beam axis will deviate when the converging lens is driven dynamically. There is a problem that a large current cannot be obtained due to deterioration. Further, since the beam axis is deviated from the center of the objective lens, there is a problem that the irradiation position of the beam on the sample surface moves when the strength (magnetic field strength) of the objective lens is changed.

JP 2004-134300 A JP 2002-257997 A JP-A-8-138600 JP-A-9-73870

  The present invention has been made to solve the above-described problems, and in a charged particle beam irradiation apparatus having a converging lens composed of a two-stage condenser lens and an objective lens, accurately adjusting the axis alignment of the charged particle beam. The main object is to prevent the charged particle beam from being displaced even by controlling the two-stage condenser lens constituting the converging lens and controlling the objective lens.

A charged particle beam irradiation apparatus according to the present invention, which has been made to solve the above-described problems, is provided between a charged particle source and a charged particle beam irradiation target surface along an axis connecting the two from the charged particle source. An objective aperture provided with a converging lens composed of a two-stage condenser lens arranged in the axial direction for converging the emitted charged particle beam, and an aperture for limiting the beam diameter of the charged particle beam converged by the converging lens In a charged particle beam irradiation apparatus comprising: a plate; and an objective lens that converges the charged particle beam that has passed through the opening of the objective aperture plate on the irradiation target surface.
An entrance-side beam deflecting means disposed between the charged particle source and the converging lens, and an exit-side beam deflecting means disposed between the converging lens and the objective aperture plate,
Each of the two beam deflecting means comprises two stages of deflectors in the axial direction for deflecting the charged particle beam.

  The deflector deflects the charged particle beam in an arbitrary direction by an arbitrary angle using either an action of a magnetic field or an electric field. The beam deflection means respectively disposed on the entrance side and the exit side of the converging lens is composed of such a two-stage deflector. By appropriately setting the deflection direction and deflection intensity of the two-stage deflector installed on the entrance side of the converging lens, the relative deviation of the center of the two-stage condenser lens in the subsequent stage can be determined. However, the axis alignment can be performed so that the beam optical axis passes through the centers of the two lenses. Also, the two-stage deflector installed on the exit side of the converging lens has an optical axis inclined with respect to the axial direction according to the relative deviation of the center of the two-stage condenser lens as described above. Although the beam is incident, the beam passes through the center of the aperture of the objective aperture plate and the center of the objective lens by appropriately setting the deflection direction and the deflection intensity of the two-stage deflector installed on the exit side of the converging lens. Can be corrected.

That is, as one aspect of the charged particle beam irradiation apparatus according to the present invention,
A first mode in which each of the two beam deflecting means corrects a tilt of an incident charged particle beam inclined with respect to the axial direction and emits the charged particle beam in the axial direction, and a charged particle beam incident in the axial direction with respect to the axial direction. A deflection control means for driving to operate in any one of the second mode for emitting light at an angle;
By operating the entrance side beam deflecting means in the second mode, the optical axis is adjusted so that the charged particle beam passes through the respective lens centers of the two-stage condenser lenses of the convergent lens, and the exit side By operating the beam deflection means in the first mode so that the charged particle beam passes through the aperture center of the objective aperture plate, and by operating the exit side beam deflection means in the second mode, The optical axis can be adjusted so that the charged particle beam passes through the lens center of the objective lens.

Moreover, the charged particle beam irradiation apparatus according to the present invention includes a detection unit that detects an irradiation region of the charged particle beam on the irradiation target surface, the exit side beam deflection unit, or the objective aperture plate and the objective lens. A scanning image forming means for generating and outputting a scanning image based on a detection signal from the detection means in a state where a scanning signal is applied to at least one of the beam scanning means disposed between,
It is preferable that the control parameters for the two beam deflecting units can be adjusted using a scanning image obtained by the scanning image forming unit.

  For example, as disclosed in Patent Document 2, the detection means may be an electron detection electrode installed on the irradiation target surface. In addition, when a secondary electron detector or the like is provided for observing the surface of the sample, such as EPMA, a sample having a known pattern formed on the surface is placed on the irradiation target surface, The irradiation region of the charged particle beam can be detected from image information created based on the secondary electrons sometimes obtained.

  When the optical axis of the charged particle beam is deviated from the center of the converging lens or the objective lens, a deviation occurs in the irradiation position of the charged particle beam on the irradiation target surface. Therefore, the scanning image forming unit adjusts the entrance side beam deflection unit based on the detection signal from the detection unit in a state where the scanning signal is applied to at least one of the exit side beam deflection unit or the beam scanning unit. And present it to the operator. The scanned image at this time becomes an image corresponding to the opening of the objective aperture plate, and the center of the aperture image is the optical axis of the charged particle beam. This makes it possible to visually confirm the state of the axis deviation when the control parameter for adjusting the axis by the entrance-side beam deflecting means is changed, thereby facilitating the parameter adjustment and efficiently performing the axis alignment operation. .

Moreover, as an axis alignment adjustment method in the charged particle beam irradiation apparatus according to the present invention,
With the first-stage condenser lens of the converging lens and the electron gun adjusted in the axial direction, first, the driving state of the first-stage condenser lens is fixed, and the driving state of the second-stage condenser lens is changed. The optical axis of the charged particle beam is adjusted by operating the entrance-side beam deflecting unit in the second mode so that the aperture image on the scanned image when changed is in the same position. It is possible to adjust the optical axis of the charged particle beam by operating the exit side beam deflecting means in the first mode so that the aperture image comes to the center of the image. Thereby, the operator can perform accurate axis alignment according to a predetermined procedure.

  According to the charged particle beam irradiation apparatus and the alignment adjustment method of the apparatus according to the present invention, the charged particle beam is placed at the center of each of the two-stage condenser lenses and the center of the objective lens that cannot adjust the relative position of the converging lens. It is possible to align the axes so that the optical axis passes. Thereby, even when the convergence of the beam is adjusted by the converging lens or the objective lens, the irradiation position of the beam does not move on the sample or the workpiece. Further, since the beam convergence is good on the sample and the workpiece, the beam current can be made sufficiently high. As a result, for example, when the charged particle beam irradiation apparatus according to the present invention is applied to EPMA, the analysis sensitivity can be improved and a desired region on the sample can be accurately analyzed regardless of the magnification or the like. it can. Furthermore, the deviation of the emission direction that occurs when the charged particle source is replaced can be adjusted by using an alignment adjustment method using the magnetic field or the electric field.

1 is a schematic configuration diagram of an electron beam irradiation apparatus according to an embodiment of the present invention. The figure which shows the correction | amendment operation mode of the electron beam optical axis in the entrance side beam deflection | deviation part and exit side beam deflection | deviation part of the electron beam irradiation apparatus of a present Example. The flowchart which shows an example of the procedure of the electron beam optical axis adjustment in the electron beam irradiation apparatus of a present Example. The schematic diagram of the electron beam optical path at the time of electron beam optical axis adjustment. The figure which shows an example of the irradiation pattern image at the time of electron beam optical axis adjustment. The schematic diagram which shows an example of the electron beam optical axis after electron beam optical axis adjustment.

Hereinafter, an electron beam irradiation apparatus for EPMA which is an embodiment of a charged particle beam irradiation apparatus according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram of an electron beam irradiation apparatus of the present embodiment.

  This electron beam irradiation apparatus deflects an electron beam as an electron beam optical system between an electron gun 1 that emits an electron beam E and an electron detection electrode 8 installed on a sample stage 9 that is irradiated with the electron beam. Then, the entrance side beam deflecting unit 2 that performs axis alignment, the converging lens system 3 including the first stage converging lens 31 and the second stage converging lens 32, each of which is a condenser lens, and the exit that deflects the electron beam and performs axis alignment A side beam deflecting unit 4, an objective aperture plate 5 in which an aperture through which an electron beam passes is formed, a scanning coil 6 that scans an irradiation position of the electron beam on a sample placed on the sample stage 9, and an electron beam An objective lens 7 for converging on the sample (electron detection electrode 8 in this figure) is provided along an axis C connecting the electron gun 1 and the sample (or electron detection electrode 8).

  The electron detection electrode 8 is not permanently installed, and may be installed on the sample stage 9 during the axis adjustment operation. The output of the electron detection electrode 8 is input to the electronic measurement unit 15, the measurement signal is input to the image processing unit 16, and the image created by the image processing unit 16 is displayed on the display unit 18. The control unit 10 including a CPU and the like includes a lens power supply unit 11 that supplies a control current to the convergent lens system 3 (convergent lenses 31 and 32) and the objective lens 7 in accordance with an operation from the operation unit 17, and an entrance side. A deflection power supply unit 12 that supplies a control current to the beam deflection unit 2 and the exit-side beam deflection unit 4 and a beam scanning power supply unit 13 that supplies a scanning current to the scanning coil 6 are controlled.

  The first-stage and second-stage converging lenses 31 and 32 are electromagnetic lenses, respectively, and are provided with apertures (capacitor apertures) 31a and 32a that limit the passage region of the electron beam. Normally, the opening size of the rear aperture 32a is slightly larger than the opening size of the front aperture 31a. The converging lens system 3 is a component in which the two-stage converging lenses 31 and 32 are integrated with a predetermined distance apart in the axis C direction. Therefore, the relative positional relationship between the converging lenses 31 and 32 is fixed, and the position of one cannot be adjusted with respect to the other.

  The entrance-side beam deflecting unit 2 and the exit-side beam deflecting unit 4 have basically the same configuration. For example, the entrance-side beam deflecting unit 2 has a first and a second arranged so as to be separated by a predetermined distance along the axis C direction. It consists of two stages of deflectors 21 and 22. One deflector 21 or 22 is composed of a pair of alignment coils arranged in directions (X and Y directions in FIG. 1) orthogonal to the axis C and orthogonal to each other, and these X and Y alignment coils. By adjusting the magnitude of the current supplied to each and the ratio of both, the passing electron beam can be bent in any direction at any angle. Therefore, each of the entrance side beam deflecting unit 2 and the exit side beam deflecting unit 4 can deflect the electron beam in different directions and different angles at two positions separated by a predetermined distance in the direction of the axis C.

  In the configuration of the present embodiment, the electron beam is deflected by the action of the magnetic field formed by the alignment coil. However, the electron beam may be deflected by the action of the electric field. That is, instead of the alignment coil, an electrode plate arranged in directions orthogonal to each other (X and Y directions) with the axis C interposed therebetween is used, and the voltage applied to the electrode plate is adjusted to adjust the deflection direction and angle of the electron beam. Can be controlled.

The basic analysis operation (observation operation) of EPMA using this electron beam irradiation apparatus is as follows.
The electron beam emitted from the electron gun 1 travels while spreading substantially along the axis C and is once converged by the converging lens system 3. Actually, as shown in FIG. 4, the focal point of the first stage converging lens 31 exists between the first stage converging lens 31 and the second stage converging lens 32, and the electron beam which is once converged here and then spreads. Is converged to the focal point in front of the objective aperture plate 5 by the second stage converging lens 32. When passing through the opening of the objective aperture plate 5, the outer edge of the electron beam E is shielded, and the electron beam that has passed through the opening is placed on the sample stage 9 by the objective lens 7 (in FIG. 1, an electron detection electrode). Equivalent to 8).

  In EPMA, X-rays are emitted from a sample by irradiation of this electron beam, and detected by an X-ray detector (not shown) disposed above the sample. At the same time, secondary electrons are emitted from the sample and detected by a secondary electron detector (not shown) disposed in proximity to the sample.

  When the control unit 10 changes (scans) the driving current supplied to the scanning coil 6 via the beam scanning power supply unit 13 according to a predetermined pattern, the electron beam is deflected by the action of the magnetic field formed by the scanning coil 6, The position where the electron beam strikes on the sample is scanned in the XY plane. Thereby, an electron beam is sequentially irradiated on the sample, and the sample surface information in the range can be acquired.

  When there is no magnetic field generated by the scanning coil 6, it is ideal that the optical axis until the electron beam emitted from the electron gun 1 reaches the sample coincides with the axis C. However, actually, the lens centers of the convergent lens system 3 and the objective lens 7 are not always on the axis C. In particular, as described above, the converging lens system 3 has a structure in which the two converging lenses 31 and 32 are integrated. Therefore, when the electron optical system is assembled, the lens centers of the two converging lenses 31 and 32 are axes. May not be on C. Therefore, in the electron beam irradiation apparatus of the present embodiment, the entrance-side beam deflecting unit 2 and the exit-side beam deflecting unit 4 each consisting of a two-stage deflector arranged in the direction of the axis C are appropriately adjusted to appropriately The optical axis of the electron beam can be adjusted.

  FIG. 2 is a conceptual diagram showing an electron beam optical axis correction operation mode in the entrance side beam deflecting unit 2 (the same applies to the exit side beam deflecting unit 4).

FIG. 2A shows a mode (mode A) in which an electron beam incident in an inclined state with respect to the axis C is corrected in the direction of the axis C and emitted. That is, in this mode, the point where the tilted incident beam axis and the axis C intersect is defined as the pivot point Pa, the distance in the axis C direction between the pivot point Pa and the first stage deflector 21 is α, and the first stage deflection. When the distance in the axis C direction between the device 21 and the second stage deflector 22 is β, the intensity ratio between the first stage deflector 21 and the second stage deflector 22 is expressed as I ₂₁ : I ₂₂ = ( α + β): α. Thus, the electron beam incident through the pivot point Pa is deflected inward (direction toward the axis C) by the first stage deflector 21, and the electron beam is deflected by the second stage deflector 22 to the first stage deflector. The beam is deflected in a direction opposite to the deflection by 21 and at a smaller angle, and emitted in the direction of the axis C.

On the other hand, FIG. 2B shows a mode (mode B) in which an electron beam incident in the direction of the axis C is corrected so as to have an inclination with respect to the axis C and emitted. That is, in this mode, the point where the tilted outgoing beam axis and the axis C intersect is the pivot point Pb, and the distance in the axis C direction between the pivot point Pb and the second stage deflector 22 is γ. The intensity ratio between the first stage deflector 21 and the second stage deflector 22 is I ₂₁ : I ₂₂ = γ: (β + γ). As a result, the electron beam incident in the direction of the axis C is deflected outward (in the direction away from the axis C) by the first stage deflector 21, and the electron beam is deflected by the next second stage deflector 22. is deflected in the opposite direction to the deflection by, emit inclined so as to pass through the pivot point P b.

  An example of the axis adjustment procedure in the electron beam irradiation apparatus of the present embodiment will be described with reference to the flowchart of FIG.

  First, the relative position between the electron gun 1 and the converging lens system 3 is adjusted before performing the axial adjustment of the electromagnetic charged particle beam, which will be described later. The position of the electron gun 1 is adjusted so that it is positioned immediately above the lens center of the first stage converging lens 31. For this purpose, the control unit 10 controls the lens power source unit 11 so as to drive only the first stage converging lens 31 in the converging lens system 3, and irradiates the electron detection electrode 8 with an electron beam (step S1).

  The control unit 10 scans the electron beam by sending a scanning signal to the first stage deflector 41 or the second stage deflector 42 of the exit side beam deflecting unit 4 via the deflection power source unit 12, and the image processing unit 16 An image in which an irradiation pattern indicating a region irradiated with an electron beam (actually an aperture image of the aperture 31a for the capacitor or the aperture plate 5) is drawn on the basis of a signal sometimes obtained by the electronic measuring unit 15 Is displayed on the display unit 18. When the electron gun 1 is not directly above the first stage converging lens 31, if the control is performed to move the focal position of the converging lens system 3 by changing the current supplied to the first stage converging lens 31 (step S2), The irradiation pattern changes in size and position. Therefore, the operator (axis adjustment operator) mechanically adjusts the position of the electron gun 1 so that the electron gun 1 comes directly above the center position of the first stage converging lens 31 while observing the irradiation pattern ( Step S3).

  In the case of a structure in which the relative positional relationship between the electron gun 1 and the converging lens system 3 is fixed and the position cannot be adjusted, for example, the entire optical element including the electron gun 1 and the converging lens system 3 is integrated. In some cases, the position adjustment in steps S1 to S3 is omitted, and the adjustment is started from the next step S4.

  At the start of the process of step S4, the lens center of the first stage converging lens 31 and the electron beam emission position of the electron gun 1 can be regarded as being located on the axis C. However, at this time, the lens center of the second stage converging lens 32 is not necessarily on the axis C. Therefore, next, axis adjustment using the entrance side beam deflecting unit 2 is performed. First, a predetermined current is supplied to the first stage converging lens 31 by the lens power supply unit 11, and the focal position of the electron beam by the converging lens 31 is fixed. Then, the current supplied to the second stage converging lens 32 is changed in a plurality of stages (in this example, two stages) to move the focal position of the electron beam by the converging lens 32. FIG. 4 shows a state in which the focal position of the electron beam is set to P1 and P2 by the drive control of the second stage converging lens 32.

  For example, in a state where the focal point of the second stage converging lens 32 is set to P1, the control unit 10 sends the exit side beam deflecting unit 4 (first stage deflector 41, second stage deflector 42) via the deflection power source unit 12. ) Is input a scanning signal for scanning in the X and Y directions. The scanning signal may be a sawtooth signal, for example, so that repeated scanning is performed. By this scanning, a substantially circular aperture image is obtained in the scanned image formed by the image processing unit 16. The position and size of the aperture image change on the scanned image obtained by scanning in the same manner with the focus of the second stage converging lens 32 being P2. Therefore, the image processing unit 16 creates an image as shown in FIG. 5A in which the aperture images corresponding to the different focal points P1 and P2 are superimposed and displays the image on the display unit 18 (step S4).

  The deviation in the position of the two aperture images reflects the deviation between the lens centers of the first and second stage converging lenses 31 and 32 and the optical axis of the electron beam. Therefore, the operator sets the correction operation mode of the entrance side beam deflecting unit 2 to the mode B shown in FIG. 2B by using the operation unit 17 while viewing the scanning image as shown in FIG. Control parameters such as currents supplied to the deflectors 21 and 22 of the entrance-side beam deflecting unit 2 are adjusted (step S5). By adjusting this control parameter, the deflection direction and deflection angle of the electron beam that exits (passes through) the entrance-side beam deflection unit 2 change.

  If the optical axis of the electron beam passes through the center of each of the two-stage converging lenses 31, 32, the center of the irradiation pattern on the electron detection electrode 8 even if the focal point of the second-stage converging lens 32 is moved. The position does not move. Therefore, even when the focal position of the second stage converging lens 32 is changed as described above, the center position of the aperture image on the scanned image does not change, that is, as shown in FIG. The control parameters for the deflectors 21 and 22 are appropriately adjusted so that the images are concentric (step S5). As a result, the optical axis of the electron beam passes through the center of each of the two-stage converging lenses 31 and 32. In this state, the deflection state of each deflector 21 and 22 of the entrance side beam deflection unit 2 is fixed.

  Next, the control unit 10 sets the correction operation mode of the exit side beam deflection unit 4 to mode A shown in FIG. 2A and then scans the exit side beam deflection unit 4 (deflectors 41 and 42). give. The operator adjusts the control parameter so as to change the beam angle by changing the deflection intensity of each of the deflectors 41 and 42 by the operation unit 17 while viewing the concentric aperture image adjusted as described above. By adjusting this control parameter, the deflection direction and deflection angle of the electron beam exiting (passing through) the exit-side beam deflection unit 4 change, and the optical axis of the electron beam in the axis C direction regardless of the tilt angle or direction of the incident beam. Can be adjusted. At this time, if the optical axis of the electron beam passes through the center of the objective lens 7, the concentric aperture image is positioned at the center of the image. Therefore, the control parameters for the deflectors 41 and 42 are adjusted so that the concentric aperture image comes to the center of the image (step S6).

Further, the control unit 10 inputs a scanning signal to the scanning coil via the beam scanning power supply unit 13 and inputs a signal for repeatedly scanning the intensity to the objective lens 7 via the lens power supply unit 11. The irradiation diameter of the electron beam on the electron detection electrode 8 is changed by the intensity scanning of the objective lens 7. In this case, the optical axis of the electron beam passing through the objective lens 7 does not coincide with the axis C, the position of the objective U O Bring image due to scanning of the objective intensity shifts. Therefore, the operator sets the correction operation mode of the exit side beam deflecting unit 4 to the mode B shown in FIG. 2B by the operation unit 17 and then displays it on the display unit 18 as shown in FIG. while watching the objective c O bling image as the objective c O Bring images so as to extend concentrically, appropriately adjusting the control parameters for each deflector 41, 42 (step S7, S8).

  FIG. 6 is a diagram showing an example of a final adjustment state when the axis adjustment is performed according to the procedure as described above. At this time, with respect to the entrance-side beam deflecting section 2, the pivot point Pa of mode A shown in FIG. 2A is located at the tip of the electron gun 1, and the pivot point Pb of mode B shown in FIG. It is located at the aperture 31 a of the first stage converging lens 31. On the other hand, with respect to the exit side beam deflecting unit 4, the pivot point Pa of mode A shown in FIG. 2A is located at the aperture 31a of the first stage converging lens 31, and the pivot of mode B shown in FIG. The point Pb is located at the center of the opening of the objective aperture plate 5. The relationship between α ′, β ′, and γ ′ shown in FIG. 6 corresponds to the relationship between α, β, and γ also shown in FIG. By performing the axis alignment in the above-described procedure, the axis adjustment is performed so that the optical axis of the electron beam passes through the center of each of the two-stage converging lenses 31 and 32 and the objective lens 7 as shown in FIG. It can be performed.

  If the electron source (filament, cathode, etc.) inside the electron gun 1 is exchanged in the state in which the axis is adjusted as described above, the emission direction of electrons from the electron source is shifted by the exchange. At this time, the entrance-side beam deflecting section 2 is scanned in mode A (a scanning signal is inputted to the upper and lower deflectors 21 and 22 at a constant ratio), and an image is detected by a detection signal by electrons passing through the opening of the objective aperture plate 5. Form. Then, adjustment is made so that the pattern scanned in mode A is centered, the emission direction of the electron source is matched, and then adjustments in steps S4 to S8 are performed, thereby performing beam adjustment after replacing the electron source. be able to.

In the above-described embodiment, the electron beam irradiation area is detected by the electron detection electrode 8 placed on the sample stage 9, but for example, an axis adjustment sample having a predetermined pattern formed on the surface is used as the sample. was placed on the stage 9, create a scanned image of the aperture image and objective c O bling image as described above appears from the secondary electron image based on secondary electrons emitted upon irradiation of electron beam to the sample You can also

  The above embodiment is an embodiment of the present invention, and it will be understood that the present invention is encompassed in the scope of the present application even if appropriate modifications, corrections and additions are made within the scope of the present invention. For example, in the above embodiment, the present invention is applied to an electron beam irradiation apparatus in which charged particles are electrons, but it is obvious that the present invention can be applied to an ion beam irradiation apparatus in which charged particles are ions.

DESCRIPTION OF SYMBOLS 1 ... Electron gun 10 ... Control part 11 ... Lens power supply part 12 ... Deflection power supply part 13 ... Beam scanning power supply part 15 ... Electron measurement part 16 ... Image processing part 17 ... Operation part 18 ... Display part 2 ... Entrance side beam deflection part 4 ... Exit-side beam deflectors 21, 41 ... first stage deflectors 22,42 ... second stage deflector 3 ... converging lens system 31 ... first stage converging lens 32 ... second stage converging lenses 31a, 32a ... capacitor aperture 41 ... deflector 5 ... objective aperture plate 6 ... scanning coil 7 ... objective lens 8 ... electron detection electrode C ... axis E ... electron beam

Claims (1)

A two-stage capacitor disposed between the charged particle source and the charged particle beam irradiation target surface in an axial direction for converging the charged particle beam emitted from the charged particle source along an axis connecting the two. A converging lens consisting of lenses,
An objective aperture plate provided with an aperture for limiting the beam diameter of the charged particle beam focused by the focusing lens;
An objective lens that converges the charged particle beam that has passed through the opening of the objective aperture plate on the irradiation target surface;
An entrance-side beam deflecting means, which is arranged between the charged particle source and the converging lens, and comprises an axially two-stage deflector for deflecting the charged particle beam;
Exit-side beam deflecting means, which is disposed between the converging lens and the objective aperture plate, and comprises an axially two-stage deflector for deflecting a charged particle beam;
A first mode in which each of the two beam deflecting means corrects a tilt of an incident charged particle beam inclined with respect to the axial direction and emits the charged particle beam in the axial direction, and a charged particle beam incident in the axial direction with respect to the axial direction. A deflection control means for driving to operate in any one of a second mode for emitting light at an angle;
At least a detection unit that detects an irradiation region of the charged particle beam on the irradiation target surface, the exit side beam deflecting unit, or a beam scanning unit disposed between the objective aperture plate and the objective lens. Scanning image forming means for creating and outputting a scanned image based on a detection signal from the detection means in a state where a scanning signal is given to one side,
A method for adjusting the axis alignment of a charged particle beam irradiation apparatus capable of adjusting a control parameter for the two beam deflection means by using a scanning image obtained by the scanning image forming means ,
The position of the electron gun is mechanically adjusted so that only the first-stage condenser lens of the convergent lens is driven and the electron gun is positioned directly above the center position of the first-stage condenser lens. wherein in a state where the first stage of the condenser lens and said electron gun is positioned axially adjustable, firstly, it changes the driving state of the fixed second stage condenser lens driving state of the first stage of the condenser lens The optical axis of the charged particle beam is adjusted by operating the entrance-side beam deflecting means in the second mode so that the aperture image on the scanned image at the same position becomes the same position, and then the aperture Adjusting the optical axis of the charged particle beam irradiation apparatus by adjusting the optical axis of the charged particle beam by operating the exit beam deflecting means in the first mode so that the image is at the center of the image. Law.

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