JP2013065578A - Method for checking failure of beam detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for checking a failure of a beam detector constituting a beam monitor.SOLUTION: A method for checking a failure of a beam detector, comprises: first measuring a beam current of an ion beam 2 by any one beam detector 12 of a plurality of beam detectors 12 while the ion beam 2 enters a beam monitor 10 disposed in a path of the ion beam 2, to store the beam current value in storage means; then sequentially measuring the beam currents of the ion beam 2 by the other beam detectors 12 of the plurality of beam detectors 12 at the same position as the first measurement while moving the beam monitor 10 by an interval between the beam detectors 12 in an X-direction, to store the beam current values in the storage means; and then comparing the stored beam current values with each other to determine whether or not the beam current value out of a predetermined allowable range exists, and, if it exists, determining that the beam detector 12 that has measured the beam current value out of the range is a failure.

Description

  The present invention relates to an ion beam measurement method for measuring a traveling angle, a divergence angle, and the like of an ion beam having a ribbon shape (also referred to as a sheet shape or a band shape) in an ion implantation apparatus or the like. Further, the present invention relates to a defect check method for checking defects of a beam detector constituting a beam monitor used for measuring an ion beam.

  Measuring method for measuring parallelism in scanning direction (X direction in Patent Document 1) of ion beam that is electrically parallel scanned using two multi-point beam monitors provided upstream and downstream of ion beam Is described in Patent Document 1. This parallelism is an angle (that is, a traveling angle) with respect to the designed traveling direction of the ion beam (that is, the traveling direction that should be originally traveled, the same applies hereinafter) in the scanning direction. This corresponds to a traveling angle in the Y direction of a ribbon-like ion beam to be described later.

Japanese Patent No. 2969788 (column 8, FIG. 4)

  The above measuring method is a measuring method of the traveling angle in the scanning direction of the ion beam, and the traveling angle in the direction substantially orthogonal to the scanning direction is not a problem in Patent Document 1, and therefore the traveling angle thereof. There is no description about the measurement method.

  However, if the traveling direction in the design of the ion beam is the Z direction, and two directions substantially orthogonal to each other in the plane substantially orthogonal to the Z direction are the X direction and the Y direction, the Y direction is larger than the dimension in the X direction. As for the ion beam having a ribbon shape with a large size in the direction, if the advancing angle in the X direction (short direction) varies in the Y direction (longitudinal direction), for example, a semiconductor substrate using the ion beam Inconvenience may occur when ion implantation is performed.

  For example, the ribbon-shaped ion beam as described above and the semiconductor substrate are mechanically scanned in a direction intersecting with the main surface of the ribbon-shaped ion beam to irradiate the semiconductor substrate with the ion beam. When ion implantation is performed, if the traveling angle of the ion beam in the X direction varies in the Y direction, it is difficult to perform uniform ion implantation on the semiconductor substrate. In particular, in recent years, semiconductor devices formed on the surface of a semiconductor substrate have been miniaturized, so the adverse effect of the variation in the advance angle is great.

The traveling angle represents a macroscopic traveling direction of the entire ion beam, but in addition to the measurement, it is also important to measure the divergence angle of the ion beam. The divergence angle of the ion beam represents a so-called microscopic traveling direction (spreading direction) of the ion beam in a small region within the ion beam.
Accordingly, an object of the present invention is to provide a measurement method capable of measuring the divergence angle of the ion beam in the X direction and the Y direction by a simple method. Another object of the present invention is to provide a defect check method for checking defects of a beam detector constituting a beam monitor used for measuring an ion beam.

  According to the beam detector defect check method of the present invention, the traveling direction of the ion beam design is the Z direction, and two directions substantially orthogonal to each other in a plane substantially orthogonal to the Z direction are the X direction and the Y direction. A beam monitor used for measurement of a ribbon-like ion beam (2) having a dimension in the Y direction larger than a dimension in the X direction, a plurality of beams receiving the ion beam and detecting the beam current, respectively. A defect check method for checking a defect of the beam detector which comprises a beam monitor (10) having a detector (12) in the X direction and movable at least in the X direction, wherein the beam monitor is In the state where the ion beam enters the ion beam path and enters the beam monitor, first, any one of the plurality of beam detectors is selected. The beam current of the ion beam is measured by the beam detector, and the beam current value is stored in the storage means. Thereafter, the beam monitor is moved in the X direction by an interval in the X direction of the beam detector. The beam current of the ion beam is sequentially measured by the remaining beam detectors of the plurality of beam detectors at the same position as the first measurement, and the beam current values are respectively stored in the storage means. The stored beam current values are compared with each other to determine whether or not there is a beam current value that is out of a predetermined allowable range. The measured beam detector is determined to be defective.

  According to the first and second aspects of the present invention, since it is possible to perform a defect check of each beam detector constituting the beam monitor, it is not necessary to use an erroneous measurement value of the beam current by the defective beam detector. . As a result, the accuracy and reliability of ion beam measurement performed using the beam monitor can be improved. For example, the accuracy and reliability of the measurement of the ion beam traveling angle, the ion beam divergence angle, and the ion beam profile (beam current density distribution) can be improved.

It is a perspective view which shows an example of a ribbon-shaped ion beam partially. It is a figure for demonstrating an example of an ion beam measuring method, (A) is a top view which shows an example of arrangement | positioning of a beam monitor etc., (B) is a figure which shows an example of the measured beam current distribution. It is a front view which shows an example of a beam monitor. It is a front view which shows the other example of a beam monitor. It is a figure which shows an example of the drive device of a beam monitor. It is a figure which shows the other example of the drive device of a beam monitor. It is a figure for demonstrating the other example of an ion beam measuring method, (A) is a top view which shows an example of arrangement | positioning of a beam monitor etc., (B) is a figure which shows an example of the measured beam current distribution. . It is a figure for demonstrating the other example of an ion beam measuring method, (A) is a side view which shows an example of arrangement | positioning of a beam monitor etc., (B) is a figure which shows an example of the measured beam current distribution. . It is a side view which shows the example which provided the some small hole in the Y direction in the mask board, and respond | corresponds to FIG. 8 (A). It is a figure for demonstrating the method to check the defect of the beam detector which comprises a beam monitor.

  FIG. 1 is a perspective view partially showing an example of a ribbon-like ion beam. In this specification and the drawings, the design traveling direction of the ion beam 2 is defined as the Z direction, and the two directions substantially orthogonal to each other in a plane substantially orthogonal to the Z direction are defined as the X direction and the Y direction. . For example, the X direction and the Z direction are horizontal directions, and the Y direction is a vertical direction. In this specification, the “designed direction of travel” refers to a predetermined direction of travel, that is, the direction of travel that should originally proceed.

The ion beam 2 has a ribbon shape in which the dimension W _{Y in the} Y direction is larger than the dimension W _{X in the} X direction without being scanned. Even if the ion beam 2 has a ribbon shape, it does not mean that the dimension W _{X in the} X direction is as thin as paper or cloth. For example, the dimension W _{X in} the X direction of the ion beam 2 is about 30 mm to 80 mm, and the dimension W _{Y in the} Y direction is about 300 mm to 500 mm, depending on the dimensions of the target substrate.

  An example of an ion beam measurement method for measuring the advancing angle θ in the X direction of the ion beam 2 (which can also be called a traveling angle measurement method) will be described with reference to FIG.

  In this measurement method, two beam monitors 10 and 20 that are provided relatively upstream and downstream in the traveling direction Z of the ion beam 2 and movable in the Y direction are used.

  The first (upstream) beam monitor 10 includes a plurality of beam detectors 12 in the X direction that receive the ion beam 2 and detect (measure) the beam current thereof. That is, it is a multi-point beam monitor having a plurality of beam detectors 12 arranged in the X direction. Each beam detector 12 is, for example, a Faraday cup. The same applies to each beam detector 22 described later.

  The plurality of beam detectors 12 may be linearly arranged in one line in the X direction as in the example shown in FIG. 3, for example, or linearly in the X direction as in the example shown in FIG. A plurality of arranged beam detectors 12 may be arranged in a zigzag pattern in two rows in the Y direction. In both examples, the plurality of beam detectors 12 are arranged at a constant interval d in the X direction. If the staggered arrangement is used, a plurality of beam detectors 12 can be arranged at a higher density in the X direction (for example, twice the density in the case of a one-row arrangement), and the measurement resolution in the X direction can be reduced. Can be increased.

  The second (downstream) beam monitor 20 is also a multi-point beam monitor having a plurality of beam detectors 22 in the X direction for detecting (measuring) the beam current upon receiving the ion beam 2. . Since the beam monitor 20 has the same structure as the beam monitor 10, the description thereof will be referred to, and a duplicate description will be omitted here. That is, the beam detector 12 described above may be read as the beam detector 22.

  The number of the beam detectors 12 and 22 constituting the beam monitors 10 and 20 is shown in FIG. 2 for simplicity of illustration in FIG. 2, but is not limited thereto. For example, the beam monitors 10 and 20 may have a total of 19 beam detectors (Faraday cups) 12 and 22 each having an ion beam entrance diameter of 5 mm arranged in a staggered manner as shown in FIG.

Referring to FIG. 2 again, using the two beam monitors 10 and 20, the center positions x ₁ and x ₂ of the ion beam 2 in the X direction are measured at substantially the same position in the Y direction. For example, the ion monitor 2 is first received and measured by the beam monitor 10, and then the beam monitor 10 is retracted from the ion beam 2 and the beam monitor 20 receives and measures the ion beam 2. The reverse order may be used.

When the ion beam 2 is deviated from the design traveling direction Z as in the example shown in FIG. 2, for example, each beam detector 12 of the beam monitor 10 is different from each other as shown by a solid line in FIG. 2B. The beam current of the specified value flows. In FIG. 2 and the like, the end portion of the ion beam 2 is represented by a line for convenience of illustration, but in reality, the end portion of the ion beam 2 has a spread, so that it has a spread as shown in FIG. 2B. A beam current flows. f _{1 to} f ₇ are the positions of the centers of the beam detectors 12 in the X direction. In the illustrated example, the beam current near the fifth beam detector 12 is larger than the others. When this discrete beam current distribution is connected by a curve, a beam current distribution 30 is obtained. For example, the position of the center of gravity of the beam current distribution 30 is set as a center position x ₁ in the X direction of the ion beam 2.

The peak position may be the center position x ₁ instead of the center of gravity position. However, since the values of the beam currents flowing in the adjacent beam detectors 12 are similar to each other and it is difficult to determine the peak position, the center of gravity position is easier to determine the center position of the ion beam 2. The same applies to the beam monitor 20. The same applies to the determination of the center position of the ion beam 2a that has passed through a small hole 62 (see FIGS. 7 to 9) of the mask plate 60 described later.

Similarly, different beam currents flow through the beam detectors 22 of the beam monitor 20 as shown by the solid lines in FIG. 2B. b _{1 to} b ₇ are the positions of the centers of the beam detectors 22 in the X direction. In the illustrated example, the beam current in the vicinity of the third beam detector 22 is larger than the others. When this discrete beam current distribution is connected by a curve, a beam current distribution 32 is obtained. For example, the position of the center of gravity of the beam current distribution 32 is set as a center position x ₂ in the X direction of the ion beam 2. Peak position instead of the position of the center of gravity may be a center position x ₂ to.

The distance L ₂ in the X direction between the two measured center positions x ₁ and x ₂ (ie, x ₁ −x ₂ or x ₂ −x ₁ ) and the distance L ₁ in the Z direction between the two beam monitors 10 and 20. Based on the above, the traveling angle θ in the X direction of the ion beam 2 is measured. The traveling angle θ is an angle in the X direction of the actual ion beam 2 with respect to the designed traveling direction Z of the ion beam 2. Specifically, since the advance angle θ can be expressed by the following equation, it is obtained.

[Equation 1]
θ = tan ⁻¹ (L ₂ / L ₁ )

In addition, the two beam monitors 10 and 20 are moved in the Y direction, and the advancing angle θ is measured at a plurality of positions in the Y direction. For example, the measurement is performed at the upper part, the central part, and the lower part of the ion beam 2 in the Y direction. In this case, as described above, the two beam monitors 10 and 20 measure the center positions x ₁ and x ₂ of the ion beam 2 at substantially the same position in the Y direction.

  According to this measuring method, since the two beam monitors 10 and 20 that are movable at multiple points in the X direction and movable in the Y direction are used, the ribbon-like ion beam 2 travels in the X direction by a simple method. The angle θ can be measured at a plurality of positions in the Y direction. As a result, the variation in the Y direction of the advance angle θ can be known by a simple method.

  FIGS. 5 and 6 show examples of driving devices for moving the beam monitors 10 and 20 in the Y direction in the vacuum vessel 6 (see FIGS. 5 and 6) to which the ion beam 2 is transported. In both figures, the beam monitor 10 is described as an example of the beam monitor, but the driving device of the beam monitor 20 is the same as this. The arrangement of the beam detectors 12 constituting the beam monitor 10 may be a linear arrangement as shown in FIG. The same applies to the beam detector 22 constituting the beam monitor 20.

  A driving device 40a shown in FIG. 5 includes a ball nut portion 46 provided in the vacuum vessel 6 to which the ion beam 2 is transported, a ball screw 44 screwed with the ball nut portion 46, and the ball screw. A reversible motor section 42 that reciprocates and a bearing section 48 that has a function of vacuum-sealing a portion through which the ball screw 44 penetrates the vacuum vessel 6 are provided. In this example, the beam monitor 10 has a ball nut section 46. It is supported by.

  The ball nut 44 and the beam monitor 10 can be moved up and down in the Y direction as indicated by arrow B by rotating the ball screw 44 left and right as indicated by arrow A by the motor part 42. Thereby, the beam monitor 10 can be positioned at a plurality of positions in the Y direction of the ion beam 2. The motor unit 42 has an encoder and can output position information of the beam monitor 10 in the Y direction.

  A driving device 40b shown in FIG. 6 is obtained by adding a mechanism for moving the beam monitor 10 in the X direction to the driving device 40a. That is, a ball nut portion 54 provided in the vacuum vessel 6, a ball screw 52 screwed with the ball nut portion 54, and a motor that is supported by the ball nut portion 46 and rotates the ball screw 52 reciprocally. The beam monitor 10 is supported by the ball nut portion 54 in this example.

  In the drive device 40b, the movement of the beam monitor 10 in the Y direction can be performed by the motor unit 42 as in the case of the drive device 40a. Further, by rotating the motor unit 50 left and right as indicated by an arrow C, the ball nut 54 and the beam monitor 10 can be moved left and right in the X direction as indicated by an arrow D. Thereby, the beam monitor 10 can be moved in the X direction within the incident region of the ion beam 2. The motor unit 50 has an encoder and can output position information of the beam monitor 10 in the X direction. The beam monitor 10 and the ball screw 44 are arranged so as to be shifted from each other before and after the ion beam traveling direction Z so that they do not hit the ball screw 44 even if the beam monitor 10 is moved in the X direction. Yes.

  When the beam monitor 10 can be moved not only in the Y direction but also in the X direction as in the driving device 40b, for example, the beam monitor 10 is separated by a distance d (in the X direction between the plurality of beam detectors 12). 3), and can be moved in the X direction by a distance of about a half of the distance (see FIG. 3, FIG. 4, FIG. 10), thereby increasing the resolution of measurement in the X direction by the beam monitor 10. Moreover, it can also be used for a defect check of the beam detector 12 described later. The same applies to the movement of the beam monitor 20.

Next, an ion beam measurement method for measuring the divergence angle of the ion beam 2 in the X direction and the Y direction (this may also be called a divergence angle measurement method) will be described with reference to FIGS. The traveling angle θ represents a macroscopic traveling direction of the entire ion beam 2, and divergence angles α _X and α _Y described below are microscopic traveling of the ion beam in a small region within the ion beam 2. It represents the direction (how to spread).

  Since the beam monitor 10 and the beam monitor 20 have the same structure, either of the beam monitors may be used in the following measurement method. Below, the case where the beam monitor 10 is used is demonstrated to an example.

This ion beam measurement method is provided with a mask plate 60 having one or more small holes 62 in the Y direction for allowing a part of the ribbon-like ion beam 2 to pass therethrough, and provided on the downstream side of the mask plate 60. The beam monitor 10 includes a plurality of beam detectors 12 that receive the ion beam 2a that has passed through the hole 62 and detect beam currents in the X direction, and are movable in the Y direction. the by moving in the Y direction, the center position x ₃ in the X direction and the Y direction of the ion beam 2a which has passed through the respective small holes 62, y ₃ were measured, respectively, the center position x _3, y ₃ mentioned above measured based on the distance L _4, L ₅ and the distance L ₃ in the Z direction between the mask plate 60 and a beam monitor 10 in the X direction and the Y direction between the small hole 62 corresponding thereto, each of Divergence angle alpha _X in the X direction and the Y direction of the ion beam 2a which passes through the hole 62, alpha _Y a is to measured.

  More specifically, in the example shown in FIGS. 7 and 8, a mask plate 60 having one small hole 62 through which a part of the ribbon-like ion beam 2 passes is provided upstream of the beam monitor 10. It is arranged. The small hole 62 is, for example, a circular small hole. The ion beam 2a that has passed through the small hole 62 is thin.

  The beam monitor 10 is configured as described above. That is, the beam monitor 10 is provided on the downstream side of the mask plate 60, and includes a plurality of beam detectors 12 that receive the ion beam 2a that has passed through the small holes 62 and detect (measure) the beam currents in the X direction. And is movable in the Y direction. An example of a driving device for driving the beam monitor 10 in the Y direction is as described above with reference to FIGS.

  Then, by moving the beam monitor 10 in the Y direction as indicated by an arrow B in FIG. 8, the center positions in the X direction and the Y direction of the ion beam 2a having passed through the small holes 62 of the mask plate 60 are measured. .

The X-direction, the traveling direction of the ion beam 2a is, for example, as in the example shown in FIG. 7, if the offset from the center position x ₄ in the X direction of the small holes 62, in each beam detector 12 of beam monitor 10 The beam current of the beam current distribution 34 as shown in FIG. 7B flows. Similar to the case of FIG. 2B, the beam current distribution 34 is displayed by connecting discrete beam current distributions with curves. For example, the position of the center of gravity of the beam current distribution 34 is set as a center position x ₃ in the X direction of the ion beam 2a. The peak position may be the center position x ₃ instead of the center of gravity position. Since the center position x ₄ in the X direction of the small holes 62 is known in advance, the distance in the X direction between the two center position x _3, x ₄ L ₄ (i.e. x ₃ -x ₄ or x ₄ -x ₃₎ Can be sought.

Similarly, for Y direction, the traveling direction of the ion beam 2a is, for example, as in the example shown in FIG. 8, if the offset from the center position y ₄ in the Y direction of the small holes 62, the ion beam 2a is incident, Focusing on one beam detector 12, a beam current having a beam current distribution 36 as shown in FIG. 8B flows through the beam detector 12 as the beam monitor 10 moves in the Y direction. The beam current distribution 36 is continuous because it is measured by the beam detector 12 moving in one Y direction. For example, the position of the center of gravity of the beam current distribution 36 is set as a center position y ₃ in the Y direction of the ion beam 2a. The peak position may be the center position y ₃ instead of the center of gravity position. Since the center position y ₄ in the Y direction of the small hole 62 is known in advance, the distance L ₅ in the Y direction between the two center positions y ₃ and y ₄ (ie, y ₃ -y ₄ or y ₄ -y ₃ ) is determined. Can be sought.

Then, based on the distances L ₄ and L ₅ and the distance L ₃ in the Z direction between the mask plate 60 and the beam monitor 10, the divergence angles α _X and Y in the X direction of the ion beam 2a that have passed through the small hole 62 are obtained. Each divergence angle α _Y is measured. Specifically, the divergence angles α _X and α _Y can be expressed by the following equations, and are thus obtained.

[Equation 2]
α _X = tan ⁻¹ (L ₄ / L ₃ )

[Equation 3]
α _Y = tan ⁻¹ (L ₅ / L ₃ )

According to this measuring method, since the beam monitor 10 that is movable at multiple points in the X direction and movable in the Y direction as described above is used, the X of the ion beam 2 at the position of the small hole 62 of the mask plate 60 can be obtained in a simple manner. The divergence angles α _X and α _Y in the direction and the Y direction can be measured. The same applies when the beam monitor 20 is used instead of the beam monitor 10.

  A plurality of small holes 62 may be provided in the mask plate 60 in the Y direction. An example is shown in FIG. FIG. 9 shows an example in which there are three small holes 62, but the present invention is not limited to this. In this case, it is preferable that the small holes 62 be separated in the Y direction so that the ion beams 2 a that have passed through the small holes 62 do not overlap each other at a position where they enter the beam monitor 10. This is to eliminate measurement errors due to overlap.

If a plurality of small holes 62 are provided as described above, the ion beam 2a that has passed through each small hole 62 is measured in the X direction and Y direction of the ion beam 2a by the measurement method described with reference to FIGS. Divergence angles α _X and α _Y in the direction can be measured. As a result, the divergence angles α _X and α _Y in the X direction and Y direction of the ion beam 2 can be measured at a plurality of positions in the Y direction of the ribbon-like ion beam 2.

  Next, a method for checking defects of the beam detectors 12 and 22 constituting the beam monitors 10 and 20 will be described with reference to FIG. Since the beam monitor 10 and the beam monitor 20 have the same structure as described above, the beam monitor 10 will be described below as an example, but the same applies to the beam monitor 20.

  When the beam monitor 10 is placed in the path of the ion beam 2 and the ion beam 2 is incident on the beam monitor 10, for example, when attention is paid to the beam detector 12 in the first row 14, first, the first row 14. The beam current of the ion beam 2 is measured by any one of the beam detectors 12 and the beam current value is stored in a storage means (not shown). Thereafter, the beam monitor 10 is moved in the X direction by the distance d of the beam detector 12, and the beam current of the ion beam 2 is sequentially measured by the other beam detector 12 at the same position as the first measurement. Store the current value. In this way, the beam current of the ion beam 2 is measured at the same position of the ion beam 2 by all the beam detectors 12 in the first row 14, and the measured beam current value is stored.

  Thereafter, the beam current values stored as described above are compared with each other to determine whether or not there is a beam current value that is out of the predetermined allowable range. The beam detector 12 that has measured the current value is determined to be defective. Further, if necessary, the defective beam detector 12 is replaced with a normal one. This is because, since the beam current is measured at the same position of the ion beam 2, if all the beam detectors 12 are normal, all the beam current values should fall within a predetermined range.

  When the beam detectors 12 of the beam monitor 10 are arranged in a staggered manner as described above, the beam detectors 12 in the second row 16 are also used by all the beam detectors 12 in the second row 16 in the same manner as described above. Measurement, storage, comparison, and defect determination of the beam current of the ion beam 2 may be performed at the same position of the ion beam 2. Further, if necessary, the defective beam detector 12 may be replaced with a normal one.

  When the beam detectors 12 constituting the beam monitor 10 are arranged in one row as in the example shown in FIG. 3, the check is performed in the same manner as described for the beam detectors 12 in the first row 14 above. And so on.

By performing the defect check of the beam detector 12 by the above method, it is not necessary to use an erroneous measurement value by the defective beam detector 12. Therefore, the measurement of the advance angle θ of the ion beam 2 and the divergence of the ion beam 2 described above. The accuracy and reliability of measurement of the angles α _X and α _Y can be improved.

  It is possible to measure the two-dimensional profile (beam current density distribution) of the ion beam 2 in the X direction and the Y direction using the beam monitor 10 that is multipoint in the X direction and movable in the Y direction. Also in this case, the accuracy and reliability of the profile measurement can be improved by performing a defect check of the beam detector 12 by the above method. The same applies when the beam monitor 20 is used.

2, 2a Ion beam 10 Beam monitor 12 Beam detector 20 Beam monitor 22 Beam detector 40a, 40b Driving device 60 Mask plate 62 Small hole

Claims (2)

If the traveling direction in the design of the ion beam is the Z direction, and two directions substantially orthogonal to each other in a plane substantially orthogonal to the Z direction are the X direction and the Y direction, the direction of the Y direction is larger than the dimension of the X direction. A beam monitor used for measuring a ribbon-shaped ion beam (2) having a large size, and having a plurality of beam detectors (12) in the X direction for receiving the ion beam and detecting the beam current, respectively. And a defect check method for checking defects of the beam detector constituting the beam monitor (10) movable at least in the X direction,
In a state where the beam monitor is put in the path of the ion beam and the ion beam is incident on the beam monitor,
First, the beam current of the ion beam is measured by any one of the plurality of beam detectors, and the beam current value is stored in the storage means.
Thereafter, the beam monitor is moved in the X direction by an interval in the X direction of the beam detector, and at the same position as the first measurement, the remaining beam detectors of the plurality of beam detectors perform the ion detection. The beam current of the beam is sequentially measured, and the beam current value is stored in the storage means.
Thereafter, the stored beam current values are compared with each other to determine whether or not there is a beam current value that is out of the predetermined allowable range. A beam detector defect check method characterized by determining that the beam detector having measured is defective. The beam monitor has a configuration in which a plurality of beam detectors arranged linearly in the X direction are arranged in a staggered manner in two rows in the Y direction,
The beam detector failure check method according to claim 1, wherein the plurality of beam detectors in the first row out of the two rows is implemented.
The beam detector defect checking method according to claim 1, wherein the beam detector defect check method according to claim 1 is performed on the plurality of beam detectors in a second row of the two rows.

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