JP6118142B2 - Electron gun apparatus, drawing apparatus, leakage current measuring method for electron gun power supply circuit, and leakage current determination method for electron gun power supply circuit - Google Patents

Description

  The present invention relates to an electron gun apparatus, a drawing apparatus, a leakage current measurement method for an electron gun power supply circuit, and a leakage current determination method for an electron gun power supply circuit. For example, the leakage of a power supply circuit for a beam source used in a charged particle beam drawing apparatus The present invention relates to a current measurement method.

  In the electron beam apparatus, an electron gun apparatus serving as a beam source is used. There are various types of electron beam apparatuses such as an electron beam drawing apparatus and an electron microscope. For example, when it comes to electron beam drawing, it has an essentially excellent resolution and is used for the production of high-precision original picture patterns.

  Lithography technology, which is responsible for the progress of miniaturization of semiconductor devices, is an extremely important process for generating a pattern among semiconductor manufacturing processes. In recent years, with the high integration of LSI, circuit line widths required for semiconductor devices have been reduced year by year. In order to form a desired circuit pattern on these semiconductor devices, a highly accurate original pattern (also referred to as a reticle or a mask) is required. The electron beam drawing apparatus is used for producing such a high-precision original pattern.

FIG. 8 is a conceptual diagram for explaining the operation of the variable shaping type electron beam drawing apparatus.
The variable shaped electron beam (EB) drawing apparatus operates as follows. In the first aperture 410, a rectangular opening 411 for forming the electron beam 330 is formed. Further, the second aperture 420 is formed with a variable shaping opening 421 for shaping the electron beam 330 having passed through the opening 411 of the first aperture 410 into a desired rectangular shape. The electron beam 330 irradiated from the charged particle source 430 and passed through the opening 411 of the first aperture 410 is deflected by the deflector, passes through a part of the variable shaping opening 421 of the second aperture 420, and passes through a predetermined range. The sample 340 mounted on a stage that continuously moves in one direction (for example, the X direction) is irradiated. That is, the drawing area of the sample 340 mounted on the stage in which the rectangular shape that can pass through both the opening 411 of the first aperture 410 and the variable shaping opening 421 of the second aperture 420 is continuously moved in the X direction. Drawn on. A method of creating an arbitrary shape by passing both the opening 411 of the first aperture 410 and the variable shaping opening 421 of the second aperture 420 is referred to as a variable shaping method (VSB method).

  In the electron beam drawing, further accuracy improvement is demanded as the integrated circuit is miniaturized. Among them are stabilization of the emission current of the electron beam emitted from the electron gun device. However, if the insulating property of each component in the electron gun apparatus is weak, a leak current is generated. Conventionally, in an electron gun device, an emission current is measured by arranging an ammeter in series with an acceleration voltage power source, for example, between a positive electrode of the acceleration voltage power source and a ground (ground). However, the value measured with such an ammeter includes both the emission current and the leakage current. Therefore, the emission current is controlled in a state where the difference between the emission current and the leakage current is not known. Therefore, when leakage current occurs, it becomes difficult to control the emission current with high accuracy. For this reason, it is necessary to grasp the leakage current generated in the electron gun device. In addition, since the insulating property varies depending on each component even in the electron gun apparatus, it is necessary to grasp how much leakage current is generated between each component and the leakage target counterpart.

JP 2002-304963 A

  Accordingly, an object of the present invention is to provide an apparatus and method that can overcome the above-described problems and can measure a leakage current for each component in the electron gun apparatus.

An electron gun device according to one embodiment of the present invention includes:
A cathode,
A grounded anode;
Wehnelt arranged between the cathode and the anode;
An acceleration voltage power supply circuit for applying an acceleration voltage between the cathode and the anode;
A bias voltage power supply circuit arranged to be electrically connected between the cathode of the acceleration voltage power supply circuit and Wehnelt, and applying a bias voltage to Wehnelt;
A filament power supply for supplying filament power to the cathode;
A first current detector arranged to be electrically connected in series between the acceleration voltage power supply circuit and the cathode;
The accelerating voltage power supply circuit is electrically connected in parallel with the first current detector, and is arranged to be electrically connected in series between the accelerating voltage power supply circuit, Wehnelt, and the bias voltage power supply circuit. A second current detection unit,
A third current detector arranged so as to be electrically connected in series to the first current detector and the second current detector with respect to the acceleration voltage power circuit;
Equipped with a,
The first, second, and third current detectors are configured such that the acceleration voltage is applied between the cathode and the anode, a bias voltage having the same potential as the acceleration voltage is applied between the Wehnelt and the anode, and Each of the current values is measured in a state where filament power is not supplied to the cathode .

The drawing device of one embodiment of the present invention includes:
An electron gun device as described above;
A drawing unit that draws a pattern on a sample using an electron beam emitted from an electron gun device;
It is provided with.

A leakage current measurement method for an electron gun power supply circuit according to an aspect of the present invention includes:
Applying an acceleration voltage between the cathode and the grounded anode;
Applying a first bias voltage having the same potential as the acceleration voltage between the anode and the Wehnelt disposed between the cathode and the anode;
An acceleration voltage is applied between the cathode and the anode, a first bias voltage is applied between Wehnelt and the anode, and an acceleration voltage is applied between the acceleration voltage power supply circuit and the cathode without supplying filament power to the cathode. Measuring a first current value flowing through
An accelerating voltage is applied between the cathode and the anode, a first bias voltage is applied between the Wehnelt and the anode, and a second current flowing between the accelerating voltage power circuit and the Wehnelt without supplying filament power to the cathode. Measuring the current value; and
It is provided with.

A step of applying a second bias voltage in which electrons are not emitted even when the cathode is heated between Wehnelt and the anode in a state where an acceleration voltage is applied between the cathode and the anode;
A third current value flowing between the acceleration voltage power supply circuit and the cathode in a state where the acceleration voltage is applied between the cathode and the anode and the second bias voltage is applied between Wehnelt and the anode, and the acceleration voltage power supply circuit Measuring at least one of a fourth current value flowing between the first and Wehnelt;
It is preferable to further include

A leakage current determination method for an electron gun power supply circuit according to an aspect of the present invention includes:
Applying an acceleration voltage between the cathode and the grounded anode;
Applying a first bias voltage having the same potential as the acceleration voltage between Wehnelt and the anode disposed between the cathode and the anode;
An acceleration voltage is applied between the cathode and the anode, a first bias voltage is applied between Wehnelt and the anode, and an acceleration voltage is applied between the acceleration voltage power supply circuit and the cathode without supplying filament power to the cathode. Measuring a first current value flowing through
An accelerating voltage is applied between the cathode and the anode, a first bias voltage is applied between the Wehnelt and the anode, and a second current flowing between the accelerating voltage power circuit and the Wehnelt without supplying filament power to the cathode. Measuring the current value; and
Determining a first current value as a first leakage current between the cathode and ground;
And a step of determining the second current value as a second leakage current between Wehnelt and ground.

  According to one embodiment of the present invention, at least leakage current between the cathode and the ground and between Wehnelt and the ground can be grasped.

1 is a conceptual diagram illustrating a configuration of a drawing apparatus according to Embodiment 1. FIG. FIG. 3 is a diagram illustrating an internal configuration of the electron gun device and an example of leakage current in the first embodiment. FIG. 6 is a flowchart showing main steps of a leakage current determination method (method 1) for an electron gun power supply circuit in the first embodiment. FIG. 6 is a flowchart showing main steps of a leakage current determination method (method 2) for an electron gun power supply circuit in the first embodiment. FIG. 3 is a graph showing a relationship between an emission current and a bias voltage in the first embodiment. FIG. 3 is a diagram showing a relationship between a detection current and a leakage current in the first embodiment. FIG. 3 is a diagram showing an internal configuration of the electron gun device and another example of leakage current in the first embodiment. It is a conceptual diagram for demonstrating operation | movement of a variable shaping type | mold electron beam drawing apparatus.

  In the following embodiments, a variable shaping type (VSB method) drawing apparatus will be described as an example of an electron beam apparatus.

Embodiment 1 FIG.
FIG. 1 is a conceptual diagram illustrating a configuration of a drawing apparatus according to the first embodiment. 1, the drawing apparatus 100 includes an electron gun device 112, a drawing unit 150, and a control circuit 160 (control unit). The drawing apparatus 100 is an example of an electron beam drawing apparatus. In particular, it is an example of a variable shaping type drawing apparatus. The drawing unit 150 includes an electron column 102 and a drawing chamber 103. In the electron column 102, an illumination lens 202, a first aperture 203, a projection lens 204, a deflector 205, a second aperture 206, an objective lens 207, a main deflector 208, and a sub deflector 209 are arranged. . In addition, an electron gun 201 that is a hardware structure portion of the above-described electron gun device 112 is disposed in the electron column 102. An XY stage 105 is disposed in the drawing chamber 103. On the XY stage 105, a sample 101 such as a mask to be drawn at the time of drawing is arranged. The sample 101 includes an exposure mask for manufacturing a semiconductor device. Further, the sample 101 includes mask blanks to which a resist is applied and nothing is drawn yet.

The electron gun device 112 includes an electron gun 201 and an electron gun power supply device 110. In the electron gun 201, a cathode 10 (cathode electrode), a Wehnelt 12 (Wehnelt electrode), and an anode 14 (anode electrode) are arranged. For example, lanthanum hexaboride (LaB ₆ ) crystal is preferably used as the cathode 10. The Wehnelt 12 is disposed between the cathode 10 and the anode 14. The anode 14 is grounded and the potential is set to the ground potential. An electron gun power supply device 110 is connected to the electron gun 201.

  Here, FIG. 1 shows a configuration necessary for explaining the first embodiment. The drawing apparatus 100 may normally have other necessary configurations.

  FIG. 2 is a diagram showing an internal configuration of the electron gun device and an example of leakage current in the first embodiment. In FIG. 2, in the electron gun power supply device 110, an acceleration voltage power supply circuit 62, a bias voltage power supply circuit 64, and a filament power supply circuit 66 (filament power supply unit) are arranged. The cathode (−) side of the acceleration voltage power circuit 62 is connected to the cathode 10 in the electron column 102. The anode (+) side of the acceleration voltage power supply circuit 62 is connected to the anode 14 in the electron column 102 and grounded (ground connection). The cathode (−) of the acceleration voltage power circuit 62 is also branched and connected to the anode (+) of the bias voltage power circuit 64, and the cathode (−) of the bias voltage power circuit 64 is connected to the cathode 10 and the anode 14. Are electrically connected to Wehnelt 12 disposed between the two. In other words, the bias voltage power supply circuit 64 is disposed so as to be electrically connected between the cathode (−) of the acceleration voltage power supply circuit 62 and the Wehnelt 12. The portion of the cathode 10 opposite to the electron emission surface is covered with a heater member (not shown). The filament power supply circuit 66 is connected to the heater member of the cathode 10. The acceleration voltage power supply circuit 62 applies an acceleration voltage between the cathode 10 and the anode 14. The bias voltage power supply circuit 64 applies a bias voltage to the Wehnelt 12. The filament power supply circuit 66 supplies filament power to the cathode 10 via the heater member.

  Here, in the first embodiment, an ammeter 70 (first current detection unit) is further arranged so as to be electrically connected in series between the acceleration voltage power supply circuit 62 and the cathode 10. The ammeter 70 is electrically connected in series on the cathode (−) side of the acceleration voltage power supply circuit 62 and on the circuit on the cathode 10 side after branching to the anode (+) side of the bias voltage power supply circuit 64. The

  The ammeter 70 is electrically connected in parallel to the ammeter 70 with respect to the acceleration voltage power supply circuit 62 and is electrically connected in series between the acceleration voltage power supply circuit 62 and the Wehnelt 12. A second current detector) is arranged. In the example of FIG. 2, the ammeter 72 is electrically connected in series between the cathode (−) of the bias voltage power supply circuit 64 and the Wehnelt 12.

  An ammeter 74 (third current detection unit) is arranged so as to be electrically connected in series to the ammeter 70 and the ammeter 72 with respect to the acceleration voltage power circuit 62. In the example of FIG. 2, the ammeter 74 is connected in series between the anode (+) and the anode 54 (ground) of the acceleration voltage power supply 62.

  The negative acceleration voltage is applied to the cathode 10 from the acceleration voltage power supply circuit 62 and the negative bias voltage is applied to the Wehnelt 12 from the bias voltage power supply circuit 64, and the cathode 10 is supplied with the power supplied from the filament power supply circuit 66. When electrons are heated, electrons (electron group) are emitted from the cathode 10, and the emitted electrons (electron group) are accelerated by the acceleration voltage and travel toward the anode 14 as an electron beam. Then, the electron beam passes through the opening provided in the anode 14, and the electron beam 200 is emitted from the electron gun 201. Thereby, the emission current Ie flows between the cathode 10 and the anode 14. In the electron gun power supply 110, the bias voltage power supply circuit 64 controls the bias voltage so as to keep the emission current Ie constant during drawing.

  Here, as shown in FIG. 2, the leakage current in the electron gun 201 includes a leakage current Icg between the cathode 10 and the ground, a leakage current Icw between the cathode 10 and the Wehnelt 12, and a leakage current between the Wehnelt 12 and the ground. The current Iwg can be assumed. In the conventional electron gun apparatus, it has been difficult to individually grasp these plural types of leakage currents. For this reason, it is difficult to determine which part has poor insulation. Therefore, in the first embodiment, the three ammeters 70, 72, and 74 are arranged at the positions described above, and a plurality of types of leakage currents are individually grasped by measuring as shown below.

  FIG. 3 is a flowchart showing main steps of the leakage current determination method (method 1) of the electron gun power supply circuit according to the first embodiment. In FIG. 3, the leakage current determination method (method 1) of the electron gun power supply circuit according to the first embodiment includes an acceleration voltage application step (S102), a bias voltage application (short-circuit connection) step (S104), and a current measurement step ( A series of steps of S106) and a determination step (S114) are performed. Among these steps, the leakage current measuring method (method 1) of the electron gun power supply circuit includes the acceleration voltage applying step (S102), the bias voltage applying (short-circuit connection) step (S104), and the current measuring step (S106). ).

  Moreover, a current measurement process (S106) implements a current Id measurement process (S108), a current Iw measurement process (S110), and a current Ir measurement process (S112) as internal processes. In Method 1, the current Ir measurement step (S112) may be omitted. In addition, as an internal process of the determination process (S114), a leakage current Icg determination process (S116) and a leakage current Iwg determination process (S118) are performed. Such a leakage current determination method (method 1) is preferably performed before the drawing apparatus 100 draws a pattern on the sample 101 (for example, when the apparatus is started up).

As an acceleration voltage application step (S102), in Method 1, first, the acceleration voltage V _ACC is applied between the cathode 10 and the grounded anode 14 from the acceleration voltage power supply circuit 62. In other words, the negative acceleration voltage V _ACC is applied from the acceleration voltage power supply circuit 62 to the cathode 10.

As a bias voltage application (short-circuit connection) step (S104), a bias voltage (first bias voltage) having the same potential as the acceleration voltage V _ACC is applied between the Wehnelt 12 and the anode. In other words, the negative bias voltage V _B having the same potential as the acceleration voltage V _ACC is applied from the bias voltage power supply circuit 64 to the Wehnelt 12. The bias voltage power supply circuit 64 applies a negative bias voltage V _B having the same potential as the acceleration voltage V _ACC to the Wehnelt 12 by short-circuiting the anode (+) and the cathode (−).

  In Method 1, filament power is not supplied from the filament power supply circuit 66 to the cathode 10. That is, since the filament power is not supplied to the heater member, the cathode 10 is not heated.

  As the current measurement step (S106), the current values of the three ammeters are measured in this state. Specifically, it is as follows.

As a current Id measurement step (S108), an acceleration voltage V _ACC is applied between the cathode 10 and the anode 14, a bias voltage V _B having the same potential as the acceleration voltage is applied between the Wehnelt 12 and the anode 14, and a filament is applied to the cathode 10. A current Id (first current value) flowing between the acceleration voltage power supply circuit 62 and the cathode 10 is measured by the ammeter 70 in a state where no power is supplied.

As the current Iw measurement step (S110), the acceleration voltage V _ACC is applied between the cathode 10 and the anode 14, the bias voltage V _B having the same potential as the acceleration voltage is applied between the Wehnelt 12 and the anode 14, and the filament is applied to the cathode 10. A current Iw (second current value) flowing between the acceleration voltage power supply circuit 62 and Wehnelt is measured by an ammeter 72 in a state where power is not supplied.

As the current Ir measurement step (S112), the acceleration voltage V _ACC is applied between the cathode 10 and the anode 14, the bias voltage V _B having the same potential as the acceleration voltage is applied between the Wehnelt 12 and the anode 14, and the filament is applied to the cathode 10. A current Ir flowing between the acceleration voltage power supply circuit 62 and the ground is measured by an ammeter 74 in a state where no power is supplied.

  When an acceleration voltage is applied between the cathode 10 and the anode 14, a bias voltage having the same potential as the acceleration voltage is applied between the Wehnelt 12 and the anode 14, and no filament power is supplied to the cathode 10, no electron beam is emitted. Therefore, no emission current flows. Therefore, a leak current is detected in each ammeter. As shown in FIG. 2, the ammeter 70 measures a leakage current Icg flowing from the ground toward the cathode 10 as a leakage 50 between the ground and the cathode 10. Similarly, the ammeter 72 measures a leak current Iwg flowing from the ground toward the Wehnelt 12 as a leak 54 between the ground and the Wehnelt 12, as shown in FIG. As shown in FIG. 2, the ammeter 74 measures the total of the leakage current Icg flowing from the ground toward the cathode 10 and the leakage current Iwg flowing from the ground toward the Wehnelt 12.

  Therefore, in the determination step (S114), the leakage current is determined as follows using the current values measured by the three ammeters 70, 72, and 74 in this state. In Method 1, since the measurement of the ammeter 74 may be omitted, it can be determined as follows using the current values measured by at least two ammeters 70 and 72.

  In the leakage current Icg determination step (S116), the current Id is determined as the leakage current Icg between the cathode 10 and the ground.

  In the leakage current Iwg determination step (S118), the current Iw is determined as the leakage current Iwg between the Wehnelt 12 and the ground.

  As described above, according to the technique 1, the leakage current Icg between the cathode 10 and the ground and the leakage current Iwg between the Wehnelt 12 and the ground can be measured and determined. However, in Method 1, since no potential difference occurs between the cathode 10 and the Wehnelt 12, no leak current flows. Therefore, it is difficult to measure the leakage current Icw between the cathode 10 and the Wehnelt 12. Therefore, as the method 2, the leakage current Icw is measured as follows.

  FIG. 4 is a flowchart showing main steps of the leakage current determination method (method 2) of the electron gun power supply circuit according to the first embodiment. In FIG. 4, the leakage current determination method (method 2) for the electron gun power supply circuit in the first embodiment includes an acceleration voltage application step (S102), a bias voltage (emission cut voltage) application step (S105), and a current measurement step. A series of steps of (S106) and a determination step (S114) are performed. In addition, among these steps, the leakage current measuring method (method) of the electron gun power supply circuit includes the acceleration voltage applying step (S102), the bias voltage (emission cut voltage) applying step (S105), and the current measuring step (S106). 2).

  In the current measurement step (S106), the current Id measurement step (S109), the current Iw measurement step (S111), and the current Ir measurement step (S113) are performed as internal steps. In Method 2, the current Iw measurement step (S111) and the current Ir measurement step (S113) may be omitted. Alternatively, the current Id measurement step (S109) and the current Ir measurement step (S113) may be omitted.

  Further, a leakage current Icw determination step (S120) is performed as an internal step of the determination step (S114). Such a leakage current determination method (method 2) is preferably carried out after method 1 and before the pattern is drawn on the sample 101 by the drawing apparatus 100 (for example, when the apparatus is started up).

  As an acceleration voltage application step (S102), in Method 2, first, an acceleration voltage is applied between the cathode 10 and the grounded anode 14 from the acceleration voltage power supply circuit 62. In other words, a negative acceleration voltage is applied from the acceleration voltage power supply circuit 62 to the cathode 10.

  As a bias voltage (emission cut voltage) application step (S105), a bias voltage (second bias voltage) that does not emit electrons even when the cathode 10 is heated is applied between the Wehnelt 12 and the anode 14.

FIG. 5 is a graph showing the relationship between the emission current and the bias voltage in the first embodiment. When supplying filament power for heating the cathode 10 to, for example, the operating temperature in a state where a predetermined acceleration voltage V _ACC is applied, the emission current Ie decreases as the bias voltage V _B increases. Become. When the bias voltage V _B exceeds a certain value, electrons are not emitted at a bias voltage higher than that, no matter how much the cathode 10 is heated. That is, the emission current Ie does not flow. In the first embodiment, a bias voltage V _{B at} which electrons are not emitted no matter how much the cathode 10 is heated is defined as an emission cut voltage (hereinafter the same). Here, for example, a bias voltage V _B ′ slightly larger than the voltage at the branch point at which the emission current Ie does not flow is applied to the Wehnelt 12. Thereby, the flow of the emission current Ie (electron emission) can be completely stopped.

  In Method 2, filament power is not supplied from the filament power supply circuit 66 to the cathode 10. That is, since the filament power is not supplied to the heater member, the cathode 10 is not heated. However, the present invention is not limited to this. Since the emission cut voltage is applied to the Wehnelt 12, even if the cathode 10 is heated, the emission current Ie does not flow. Therefore, there is no need to measure the leakage current, but filament power may be supplied from the filament power supply circuit 66 to the cathode 10.

  As the current measurement step (S106), the current values of the three ammeters are measured in this state. Specifically, it is as follows.

  As a current Id measurement step (S109), an acceleration voltage is applied between the cathode 10 and the anode 14, a bias voltage (second bias voltage) of an emission cut voltage is applied between the Wehnelt 12 and the anode 14, and the cathode 10 is applied. A current Id (third current value) flowing between the acceleration voltage power supply circuit 62 and the cathode 10 is measured by the ammeter 70 in a state where the filament power is not supplied. As described above, the filament power may be supplied to the cathode 10 for measurement.

  In the current Iw measurement step (S111), an acceleration voltage is applied between the cathode 10 and the anode 14, a bias voltage of an emission cut voltage is applied between the Wehnelt 12 and the anode 14, and no filament power is supplied to the cathode 10. The current Iw (fourth current value) flowing between the acceleration voltage power supply circuit 62 and Wehnelt is measured by an ammeter 72. As described above, the filament power may be supplied to the cathode 10 for measurement.

  In the current Ir measurement step (S112), an acceleration voltage is applied between the cathode 10 and the anode 14, a bias voltage of an emission cut voltage is applied between the Wehnelt 12 and the anode 14, and no filament power is supplied to the cathode 10. The current Ir flowing between the acceleration voltage power supply circuit 62 and the ground is measured by an ammeter 74. As described above, the filament power may be supplied to the cathode 10 for measurement.

  In the state where the acceleration voltage is applied between the cathode 10 and the anode 14 and the bias voltage of the emission cut voltage is applied between the Wehnelt 12 and the anode 14, the electron beam is not emitted. Therefore, no emission current flows. However, in Method 2, since a potential difference is generated between the cathode 10 and the Wehnelt 12, there is a possibility that a leakage current Icw flows from the cathode 10 toward the Wehnelt 12 between the cathode 10 and the Wehnelt 12. . Therefore, the ammeter 70 includes a leakage current Icg flowing from the ground toward the cathode 10 as a leakage 50 between the ground and the cathode 10 and a cathode as a leakage 52 between the cathode 10 and the Wehnelt 12 as shown in FIG. The difference from the leakage current Icw flowing from 10 to Wehnelt 12 is measured. Since the direction of the loop through which the current flows is reversed, it becomes a difference. In addition, as shown in FIG. 2, the ammeter 72 includes a leak current Icw flowing from the cathode 10 toward the Wehnelt 12 as a leak 52 between the cathode 10 and the Wehnelt 12, and a leak 54 between the ground and the Wehnelt 12. The sum of the leakage current Iwg flowing from the ground toward the Wehnelt 12 is measured. Since the direction of the loop through which the current flows is the same, the sum is obtained. As shown in FIG. 2, the ammeter 74 measures the total of the leakage current Icg flowing from the ground toward the cathode 10 and the leakage current Iwg flowing from the ground toward the Wehnelt 12.

  Therefore, in the determination step (S114), the leakage current is determined as follows using the current values measured by the three ammeters 70, 72, and 74 in this state. In the method 2, the measurement of the ammeter 74 may be omitted, and at least one of the measurement of the ammeter 70 and the measurement of the ammeter 72 may be performed. Therefore, it can be determined as follows using one of the current values measured by the two ammeters 70 and 72.

  In the leakage current Icw determination step (S120), the leakage current Icw is determined as follows. When the current Id is measured, the current Id is the difference between the leak current Icg and the leak current Icw. Therefore, the leak current Icw can be calculated by subtracting the current Id from the leak current Icg obtained by the technique 1. Therefore, the difference between the leakage current Icg and the current Id obtained by the method 1 is determined as the leakage current Icw.

  Alternatively, when the current Iw is measured, the current Iw is the sum of the leak current Iwg and the leak current Icw. Therefore, the leak current Icw is calculated by subtracting the leak current Iwg obtained by the method 1 from the current Iw. it can. Therefore, the difference between the current Iw and the leak current Iwg obtained by the method 1 is determined as the leak current Icw.

  FIG. 6 is a diagram showing the relationship between the detection current and the leakage current in the first embodiment. As shown in FIG. 6, in Method 1, the current Id measured by the ammeter 70 can be detected as a leak current Icg flowing from the ground toward the cathode 10. Similarly, the current Iw measured by the ammeter 72 can be detected as a leak current Iwg flowing from the ground toward the Wehnelt 12. The current Ir measured by the ammeter 74 can be detected as the sum of the leak current Icg flowing from the ground toward the cathode 10 and the leak current Iwg flowing from the ground toward the Wehnelt 12.

  As shown in FIG. 6, in Method 2, the current Id measured by the ammeter 70 includes a leak current Icg flowing from the ground toward the cathode 10 and a leak current Icw flowing from the cathode 10 toward the Wehnelt 12. It can be detected as the difference between The current Iw measured by the ammeter 72 can be detected as the sum of the leakage current Icw flowing from the cathode 10 toward the Wehnelt 12 and the leakage current Iwg flowing from the ground toward the Wehnelt 12. The current Ir measured by the ammeter 74 can be detected as the sum of the leak current Icg flowing from the ground toward the cathode 10 and the leak current Iwg flowing from the ground toward the Wehnelt 12.

  As described above, according to the first embodiment, it is possible to individually grasp a plurality of types of leakage currents. Therefore, it is possible to determine which part is weak in insulation. Then, it is determined whether or not each leakage current measured before drawing by the drawing apparatus 100 is larger than the respective threshold value. If the leakage current is larger, the part may be replaced or an improvement for improving the insulation may be performed. As a result, for example, an initial trouble at the time of starting up the apparatus can be prevented.

  As described above, after confirming that each leakage current is equal to or less than the threshold value or performing maintenance so as to be equal to or less than the threshold value, the drawing apparatus 100 performs a drawing operation.

  As a drawing process, the drawing unit 150 draws a pattern on the sample 101 using the electron beam 200 emitted from the electron gun device 112. Specifically, it operates as follows. First, drawing data (not shown) is input by the control circuit 160, and a plurality of stages of data conversion processing is performed on the drawing data to generate apparatus-specific shot data. Here, a plurality of graphic patterns are usually defined in the drawing data. In order to draw a figure pattern with the drawing apparatus 100, it is necessary to divide each figure pattern into a size that can be irradiated with one shot of a beam. Therefore, in the control circuit 160, in order to actually draw, a shot figure is generated by dividing each figure pattern into a size that can be irradiated with one beam shot. Then, shot data is generated for each shot figure. In the shot data, for example, graphic data such as a graphic type, a graphic size, and an irradiation position are defined. In addition, irradiation amount (irradiation time) data and the like are defined. The generated shot data is stored in a storage device (not shown). The drawing unit 150 controlled by the control circuit 160 operates as follows according to the shot data.

  In the electron gun device 112, when the cathode 10 is heated with a constant negative Wehnelt voltage (bias voltage) applied to the Wehnelt 12 and a constant negative acceleration voltage applied to the cathode 10, electrons are emitted from the cathode 10. The (electron group) is emitted, and the emitted electron (electron group) is accelerated by the acceleration voltage to become an electron beam and travel toward the anode 14. As a result, the electron beam 200 is emitted from the electron gun 201. The bias voltage applied to the Wehnelt 12 is a constant current control voltage through which an emission current flows. The constant current control voltage is set to an optimum value depending on, for example, a desired emission current. Needless to say, the optimum value is smaller than the above-described emission cut voltage. Further, the filament power is supplied to the cathode 10 (or a heater (not shown)) so that the cathode 10 has an optimum operating temperature for a desired emission current.

  The electron beam 200 emitted from the electron gun 201 (emission unit) illuminates the entire first aperture 203 having a rectangular hole by the illumination lens 202. Here, the electron beam 200 is first shaped into a rectangle. Then, the electron beam 200 of the first aperture image that has passed through the first aperture 203 is projected onto the second aperture 206 by the projection lens 204. The deflector 205 controls the deflection of the first aperture image on the second aperture 206, and can change (variably shape) the beam shape and dimensions. The electron beam 200 of the second aperture image that has passed through the second aperture 206 is focused by the objective lens 207, deflected by the main deflector 208 and the sub deflector 209, and continuously moved. The desired position of the sample 101 arranged in the above is irradiated. FIG. 1 shows a case in which multi-stage deflection of main and sub two stages is used for position deflection. In such a case, the electron beam 200 of the corresponding shot is obtained by following the stage movement by the main deflector 208 to the reference position of the subfield (SF) obtained by further dividing the stripe area in which the drawing area of the sample 101 is divided into strips. And the sub-deflector 209 deflects the corresponding shot beam at each irradiation position in the SF.

  Even during such drawing, it is preferable to detect the values of the ammeters 70, 72, and 74 as the method 3. In Method 3, as shown in FIG. 6, the current Id measured by the ammeter 70 can be detected as a value obtained by subtracting the leakage current Icw from the sum of the emission current Ie and the leakage current Icg. The current Iw measured by the ammeter 72 can be detected as the sum of the leakage current Icw and the leakage current Iwg. The current Ir measured by the ammeter 74 can be detected as the sum of the emission current Ie, the leakage current Icg, and the leakage current Iwg. Therefore, a value obtained by subtracting the difference between the leakage current Icg and the leakage current Icw from the current Id can be detected as the actual emission current Ie. Alternatively, a value obtained by subtracting the sum of the leakage current Icg and the leakage current Iwg from the current Ir can be detected as the actual emission current Ie. Since the value of each leakage current is known in advance before starting drawing on the sample 101, the emission current Ie can be grasped with high accuracy. Therefore, it is possible to control the emission current with high accuracy in real time during drawing.

  FIG. 7 is a diagram illustrating an internal configuration of the electron gun device according to Embodiment 1 and another example of leakage current. 7 is the same as FIG. 2 except that the arrangement positions of the ammeters 72 and 74 are different. In the example of FIG. 2, the ammeter 72 is electrically connected in series between the cathode (−) of the bias voltage power supply circuit 64 and the Wehnelt 12. However, the present invention is not limited to this, and as shown in FIG. 7, the ammeter 72 branches to the cathode (−) side of the acceleration voltage power circuit 62 and to the anode (+) side of the bias voltage power circuit 64. It may be electrically connected in series on the circuit up to the anode (+) of the later bias voltage power supply circuit 64.

  In the example of FIG. 2, the ammeter 74 is connected in series between the anode (+) and the anode 54 (ground) of the acceleration voltage power supply 62. However, the present invention is not limited to this, and the ammeter 74 branches to the anode (+) side of the bias voltage power supply circuit 64 even if it is on the cathode (−) side of the acceleration voltage power supply circuit 62 as shown in FIG. Any circuit may be used as long as it is electrically connected in series on the circuit before the operation.

The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. The electron gun apparatus on which the selected cathode is mounted is not limited to the drawing apparatus, but can be applied to other electron beam apparatuses such as an electron microscope. Further, as the cathode material has been described as an example LaB ₆ crystal, a tungsten (W), such as cerium hexaboride (CeB _6), it can be applied to other thermionic emission material. Further, although a carbon film is used to limit the electron emission surface of the cathode, it is not limited to carbon. In addition, any material such as rhenium (Re) having a higher work function than the electron emission material may be used.

  In addition, although descriptions are omitted for parts and the like that are not directly required for the description of the present invention, such as a device configuration and a control method, a required device configuration and a control method can be appropriately selected and used. For example, although the description of the control unit configuration for controlling the drawing apparatus 100 is omitted, it goes without saying that the required control unit configuration is appropriately selected and used.

  In addition, all cathode selection methods, cathode selection measuring devices, electron beam drawing apparatuses, and methods that include elements of the present invention and can be appropriately modified by those skilled in the art are included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Cathode 12 Wehnelt 14 Anode electrode 62 Acceleration voltage power supply circuit 64 Bias voltage power supply circuit 66 Filament power supply circuit 70,72,74 Ammeter 100 Drawing apparatus 101,340 Sample 102 Electron barrel 103 Drawing chamber 105 XY stage 112 Electron gun power supply 150 Drawing unit 160 Control circuit 200 Electron beam 201 Electron gun 202 Illumination lenses 203 and 410 First aperture 204 Projection lens 205 Deflector 206 and 420 Second aperture 207 Objective lens 208 Main deflector 209 Sub deflector 300 Measuring device 330 Electron beam 411 Opening 421 Variable shaping opening 430 Charged particle source

Claims (5)

A cathode,
A grounded anode;
Wehnelt disposed between the cathode and the anode;
An acceleration voltage power supply circuit for applying an acceleration voltage between the cathode and the anode;
A bias voltage power supply circuit arranged to be electrically connected between the cathode of the acceleration voltage power supply circuit and the Wehnelt, and applying a bias voltage to the Wehnelt;
A filament power supply for supplying filament power to the cathode;
A first current detector disposed so as to be electrically connected in series between the acceleration voltage power supply circuit and the cathode;
The acceleration voltage power supply circuit is electrically connected in parallel with the first current detection unit, and is electrically connected in series between the acceleration voltage power supply circuit, the Wehnelt, and the bias voltage power supply circuit. A second current detector arranged to be
A third current detection unit disposed so as to be electrically connected in series to the first current detection unit and the second current detection unit with respect to the acceleration voltage power supply circuit;
Equipped with a,
The first, second, and third current detectors are configured such that the acceleration voltage is applied between the cathode and the anode, a bias voltage having the same potential as the acceleration voltage is applied between the Wehnelt and the anode, and An electron gun apparatus that measures current values in a state where filament power is not supplied to the cathode . An electron gun device according to claim 1,
A drawing unit that draws a pattern on a sample using an electron beam emitted from the electron gun device;
A drawing apparatus comprising: Applying an acceleration voltage between the cathode and the grounded anode;
Applying a first bias voltage having the same potential as the accelerating voltage between the Wehnelt disposed between the cathode and the anode and the anode;
The acceleration voltage is applied between the cathode and the anode, the first bias voltage is applied between the Wehnelt and the anode, and the acceleration voltage is applied without supplying filament power to the cathode. Measuring a first current value flowing between a voltage power supply circuit and the cathode;
The acceleration voltage is applied between the cathode and the anode, the first bias voltage is applied between the Wehnelt and the anode, and no filament power is supplied to the cathode. Measuring a second current value flowing to and from Wehnelt;
A leakage current measurement method for an electron gun power supply circuit, comprising: Applying a second bias voltage that does not emit electrons even when the cathode is heated between the Wehnelt and the anode in a state where the acceleration voltage is applied between the cathode and the anode;
A third current that flows between the acceleration voltage power supply circuit and the cathode in a state where the acceleration voltage is applied between the cathode and the anode and the second bias voltage is applied between the Wehnelt and the anode. Measuring at least one of a current value and a fourth current value flowing between the acceleration voltage power supply circuit and the Wehnelt;
4. The method for measuring a leakage current of an electron gun power supply circuit according to claim 3, further comprising: Applying an acceleration voltage between the cathode and the grounded anode;
Applying a first bias voltage having the same potential as the acceleration voltage between a Wehnelt and an anode disposed between the cathode and the anode;
The acceleration voltage is applied between the cathode and the anode, the first bias voltage is applied between the Wehnelt and the anode, and the acceleration voltage is applied without supplying filament power to the cathode. Measuring a first current value flowing between a voltage power supply circuit and the cathode;
The acceleration voltage is applied between the cathode and the anode, the first bias voltage is applied between the Wehnelt and the anode, and no filament power is supplied to the cathode. Measuring a second current value flowing to and from Wehnelt;
Determining the first current value as a first leakage current between the cathode and ground;
And a step of determining the second current value as a second leakage current between the Wehnelt and the ground.

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