JP7086811B2 - Electron gun and electron beam device - Google Patents

Description

Embodiments of the present invention relate to electron guns and electron beam devices.

Regarding the current density distribution of the electron beam emitted from the cathode of the electron gun, the current density near the center position of the beam region is the maximum, and the current density becomes smaller toward the periphery. Therefore, an aperture member is provided inside the electron gun, and only a part of the beam region of the electron beam, specifically, a portion having a uniform current density near the center position of the beam region is emitted from the electron gun. As a result, the proportion of the electron beam that collides with the aperture member and is absorbed is larger than that of the electron beam that passes through the aperture member.

The larger the ratio of the electron beam that collides with the aperture member and is absorbed, the more energy is accumulated in the aperture member and the heat is easily generated. As the current density of the electron beam emitted from the electron gun increases, as in a multi-beam device, the amount of heat generated by the aperture member inside the electron gun increases, and the aperture member becomes easier to melt.

Japanese Unexamined Patent Publication No. 2001-312986

An object to be solved by the present invention is to provide an electron gun and an electron beam device in which the aperture member inside the electron gun is prevented from melting.

According to this embodiment, a cathode that emits an electron beam and
A first aperture member that allows a part of the electron beam to pass through and shields the remaining electron beam.
A first anode arranged between the cathode and the first aperture member,
A second anode arranged between the first aperture member and the second aperture member through which the electron beam passing through the first anode passes, and to which a voltage higher than that of the first anode is applied. An electron gun is provided to prepare.

The block diagram which shows the schematic structure of the electron beam apparatus by one Embodiment. The figure which shows the internal structure of the electron gun by this embodiment. The figure which shows the internal structure of the electron gun by one comparative example. (A) is a diagram showing a region in which the current density is uniform in the beam region of the electron beam emitted from the cathode, and (b) is a diagram showing the current density distribution of the electron beam emitted from the cathode.

Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the drawings attached to the present specification, the scale, aspect ratio, etc. are appropriately changed from those of the actual product and exaggerated for the convenience of illustration and comprehension.

FIG. 1 is a block diagram showing a schematic configuration of an electron beam device 1 according to an embodiment. The electron beam apparatus 1 in FIG. 1 is a multi-beam drawing apparatus 2. The electron beam apparatus 1 according to the present embodiment can be applied not only to the multi-beam drawing apparatus 2 but also to the single-beam drawing apparatus. Further, the electron beam apparatus 1 according to the present embodiment can be applied not only to a drawing apparatus but also to an inspection apparatus. As described above, the electron beam apparatus 1 according to the present embodiment can be applied to an apparatus for drawing on the sample 20 or inspecting the sample 20 by using a multi-beam or a single beam. An example applied to the multi-beam drawing device 2 will be mainly described.

The multi-beam drawing device 2 of FIG. 1 includes a drawing unit 3 and a control unit 4. The drawing unit 3 has an electronic lens barrel 5 and a drawing chamber 6. The electron barrel 5 includes an electron gun 8 having a first aperture member 7, an illumination lens 9, a second aperture member 10, a third aperture member 11, a reduction lens 12, a fourth aperture member 13, and an objective. It has a lens 14 and a deflector 15. The drawing chamber 6 has an XY stage 16 and a mirror 17.

The internal configuration of the electron gun 8 will be described later. The illumination lens 9 includes a collimator lens, and parallelizes the electron beam emitted from the electron gun 8 to guide the electron beam to the second aperture member 10. The second aperture member 10 has a plurality of openings, and the electron beam emitted from the electron gun 8 is passed through these openings to generate a multi-beam.

The third aperture member 11 is also referred to as a blanking aperture array. The third aperture member 11 is a semiconductor chip (BAA chip) mounted on a substrate, and this substrate is mounted on the blanking aperture stage device 18. The individual beams constituting the multi-beam that has passed through the second aperture member 10 are individually deflected and controlled by the third aperture member 11. The third aperture member 11 has a plurality of openings, and the multi-beam passing through these openings is guided to the fourth aperture member 13. That is, a part of the multi-beams that have passed through the third aperture member 11 pass through the fourth aperture member 13, and the remaining beams collide with the fourth aperture member 13 and are absorbed. The beam that has passed through the fourth aperture member 13 is positioned and irradiated on the sample 20 placed on the XY stage 16 by controlling the position by the deflector 15.

The control unit 4 of FIG. 1 includes a control computer 21, a memory 22, a deflection control circuit 23, a stage position detector 24, a first storage unit 25, and a second storage unit 26.

The control computer 21 includes a data processing unit 27 that processes various data and a drawing control unit 28 that controls the drawing operation of the multi-beam drawing device 2. The data processing unit 27 and the drawing control unit 28 may be configured by hardware built in the control computer 21 or by software by a program executed by the control computer 21. The input / output information and the information being calculated in the data processing unit 27 and the drawing control unit 28 are stored in the memory 22 as needed. The drawing control unit 28 includes drawing data stored in the first storage unit 25, irradiation time data of each shot stored in the second storage unit 26, and the position of the XY stage 16 detected by the stage position detector 24. The deflection control circuit 23 is controlled based on the above. The deflection control circuit 23 controls the deflection of the multi-beam in the third aperture member 11 (blanking aperture array), and also controls the deflection direction of the beam in the deflector 15.

FIG. 2 is a diagram showing an internal configuration of the electron gun 8 according to the present embodiment. The electron gun 8 shown in FIG. 2 has a cathode 31, a Wehnelt electrode 32, a first anode 33, an aligner 34, a first aperture member 7, and a second anode 35.

The cathode 31 is set to, for example, 0V. A negative voltage lower than 0 V is applied to the Wehnelt electrode 32. The first anode 33 is arranged between the cathode 31 and the first aperture member 7. More specifically, the first anode 33 is arranged between the cathode 31 and the aligner 34. The aligner 34 is provided to control the direction of the electron beam emitted from the cathode 31. That is, the aligner 34 controls the direction of the electron beam so that the portion of the beam region of the electron beam emitted from the cathode 31 has a uniform current density passes through the first aperture member 7. The aligner 34 can be configured with an electrostatic deflector or a magnetic field deflector.

In this embodiment, the voltage applied to the first anode 33 is made as small as possible. Therefore, the electron beam emitted from the cathode 31 reaches the first aperture member 7 without having so much energy. Since the first aperture member 7 passes only the portion of the beam region of the electron beam accelerated by the first anode 33 where the current density is uniform, most of the electron beam collides with the first aperture member 7 and is absorbed. Will be done. Therefore, the first aperture member 7 may generate heat. However, in the present embodiment, the voltage applied to the first anode 33 is smaller than that in the conventional case, so that the electrons collide with the first aperture member 7 and are absorbed. The energy of the beam does not increase so much. Therefore, even if the first aperture member 7 absorbs the electron beam and generates heat, there is no possibility that the first aperture member 7 will generate heat as it melts.

As shown in FIG. 2, in the present embodiment, the second anode 35 is arranged between the first aperture member 7 and the second aperture member 10. More specifically, the second anode 35 is arranged between the first aperture member 7 and the collimator lens 36. The collimator lens 36 parallelizes (colimates) the electron beam accelerated by the second anode 35 and passes it through the second aperture member 10. The collimator lens 36 corresponds to the illumination lens 9 of FIG.

A voltage higher than that of the first anode 33 is applied to the second anode 35. That is, in the present embodiment, instead of suppressing the voltage applied to the first anode 33, the acceleration voltage that should be originally applied to the electron gun 8 is applied to the second anode 35. For example, 50 kV is applied to the second anode 35. As a result, the electron beam emitted from the cathode 31 passes through the first aperture member 7 and then is rapidly accelerated to pass through the second aperture member 10. Since most of the electron beam that has passed through the first aperture member 7 passes through the second aperture member 10, even if the electron beam is rapidly accelerated between the first aperture member 7 and the second aperture member 10, the second aperture is used. There is no risk that the member 10 will heat up.

As described above, in the electron gun 8 of FIG. 2, the electron beam can be accelerated and emitted with a sufficient acceleration voltage while suppressing the heating of the first aperture member 7.

FIG. 3 is a diagram showing an internal configuration of the electron gun 8a according to a comparative example. In the electron gun 8a of FIG. 3, the anode 37 is arranged between the cathode 31 and the aligner 34, and there is no anode between the first aperture member 7 and the second aperture member 10. For example, 50 kV is applied to the anode 37 in FIG. Therefore, in the case of FIG. 3, most of the high-energy electron beams accelerated by the anode 37 collide with the first aperture member 7 without passing through the first aperture member 7 and are absorbed, so that the first aperture member 7 is absorbed. May generate heat and dissolve.

FIG. 4A is a diagram showing a region in which the current density is uniform in the beam region of the electron beam emitted from the cathode 31, and FIG. 4B is a diagram showing the current density distribution of the electron beam emitted from the cathode 31. Is. The relationship between the current I (n) in the beam region having a uniformity of current density of n or more and the current (emission current) It of the electron beam emitted from the cathode 31 is expressed by the following equation (1). To.
I (n) = It (1-n) ... (1)

When n = 0.9, I (n) = 0.1 × It, and 90% of the emission current is absorbed by the aperture. When 100 μA is required as the beam current passing through the second aperture member 10, a current of 900 μA is absorbed by the first aperture member 7. In the case of the electron gun 8 of FIG. 3, since a voltage of 50 kV is applied to the anode arranged between the cathode 31 and the first aperture member 7, an electron beam having a power of 50 kV × 0.9 mA = 45 W is the first aperture member. It is absorbed by 7. When such a high-energy electron beam is absorbed by the first aperture member 7, the first aperture member 7 is melted. When a refractory metal such as tungsten or tantalum is used as the material of the first aperture member 7, the first aperture portion may be melted.

On the other hand, in the electron gun 8 of the present embodiment shown in FIG. 2, the first anode 33 is provided between the cathode 31 and the first aperture member 7, and the first aperture member 7 and the second aperture member 10 are provided. A second anode 35 is provided between the two, and a voltage sufficiently lower than that of the second anode 35 is applied to the first anode 33. As an example, when an electron gun 8 applies an acceleration voltage of 50 kV to emit an electron beam, a voltage of, for example, 10 kV is applied to the first anode 33 and the first aperture member 7, and a voltage of, for example, 50 kV is applied to the second anode 35. Apply the voltage of. Since only a voltage of 10 kV, which is 1/5 of 50 kV, is applied to the first anode 33, the electric power of the electron beam that collides with the first aperture member 7 and is absorbed is also reduced to 1/5, and the first aperture is melted. There is no fear.

The lower the voltage applied to the first anode 33, the smaller the power of the electron beam that collides with the first aperture member 7 and is absorbed. Therefore, when it is necessary to apply an acceleration voltage of 50 kV to the electron gun 8, it is possible to make the voltage applied to the first anode 33 less than 10 kV, but the voltage applied to the first anode 33 is low. If it is too much, the electron beam will not be emitted from the cathode 31. In particular, since a negative voltage is applied to the Wenert electrode 32 arranged between the cathode 31 and the first anode 33, electrons are emitted from the cathode 31 unless the voltage applied to the first anode 33 is a positive voltage higher than a certain level. The beam will not be emitted. According to the study of the present inventor, for example, when it is necessary to apply an acceleration voltage of 50 kV to the electron gun 8, the electrons are stably emitted from the cathode 31 unless the voltage applied to the first anode 33 is about 3 kV or more. The beam will not be emitted.

The minimum value of the voltage applied to the first anode 33 varies depending on the material of the first aperture member 7, the size of the electron gun 8, and the like, and therefore cannot be unconditionally specified.

Further, it is not always necessary to apply the same voltage to the first anode 33 and the first aperture member 7. For example, 5 kV may be applied to the first anode 33 and 10 kV may be applied to the first aperture member 7.

As described above, the first anode 33 is provided between the cathode 31 and the aligner 34, and a voltage lower than that of the second anode 35 is applied to the first anode 33 to prevent the first aperture member 7 from melting. However, if the irradiation time of the electron beam is long, the first anode member 7 may be melted. Therefore, it is desirable not only to provide the first anode 33 but also to use a refractory metal such as tungsten or tantalum as the material of the first aperture member 7.

When it is necessary to accelerate the electron beam with an acceleration voltage larger than 50 kV with the electron gun 8, the second anode 35 may be multi-staged. That is, the second anode 35 may be composed of a plurality of stages of anode portions arranged in the traveling direction of the electron beam, and a higher voltage may be applied to the anode portion closer to the collimator lens. As the number of anode portions is increased, the potential difference between adjacent anode portions can be reduced, so that there is no possibility that each anode portion causes dielectric breakdown. As described above, it is desirable to apply a voltage as low as possible to the first anode 33, so it is not desirable to have the first anode 33 in a multi-stage configuration.

As described above, in the electron gun 8 according to the present embodiment, the first anode 33 is provided between the cathode 31 and the first aperture member 7, and the second anode 35 is provided between the first aperture member 7 and the second aperture member 10. Since a voltage lower than that of the second anode 35 is applied to the first anode 33, the energy of the electron beam that collides with the first aperture member 7 and is absorbed can be suppressed, and the heat generation of the first aperture member 7 is suppressed. It is possible to prevent the problem that the first aperture member 7 is melted. The electron gun 8 according to the present embodiment can be widely applied to a multi-beam or single-beam electron beam drawing device or inspection device, and can be used by replacing the electron gun 8 of the existing electron beam drawing device or inspection device. , The life of the electron gun 8 in the drawing apparatus and the inspection apparatus can be extended.

Aspects of the present invention are not limited to the individual embodiments described above, but include various modifications that can be conceived by those skilled in the art, and the effects of the present invention are not limited to the above-mentioned contents. That is, various additions, changes and partial deletions are possible without departing from the conceptual idea and purpose of the present invention derived from the contents defined in the claims and their equivalents.

1 Electron beam device, 2 Multi-beam drawing device, 3 Drawing unit, 4 Control unit, 5 Electronic lens barrel, 6 Drawing chamber, 7 1st aperture member, 8, 8a electron gun, 9 Illumination lens, 10 2nd aperture member, 11 3rd aperture member, 12 reduction lens, 13 4th aperture member, 14 objective lens, 15 deflector, 16 XY stage, 17 mirror, 18 blanking aperture stage device, 20 samples, 21 control computer, 22 memory, 23 deflection Control circuit, 24 stage position detector, 25 1st storage unit, 26 2nd storage unit, 27 data processing unit, 28 drawing control unit, 31 cathode, 32 Wenert electrode, 33 1st anode, 34 aligner, 35 2nd anode , 36 collimeter lens, 37 anode

Claims (5)

A cathode that emits an electron beam and
A first aperture member that allows a part of the electron beam to pass through and shields the remaining electron beam.
A first anode arranged between the cathode and the first aperture member,
A Wehnelt electrode arranged between the cathode and the first anode and to which a negative voltage is applied,
A second anode arranged between the first aperture member and the second aperture member through which the electron beam passing through the first anode passes is provided.
The acceleration voltage of the electron beam emitted from the cathode is applied to the second anode.
An electron gun to which a positive voltage lower than the acceleration voltage applied to the second anode and higher than the negative voltage applied to the Wehnelt electrode is applied to the first anode . A liner for controlling the direction of the electron beam emitted from the cathode is provided.
The electron gun according to claim 1, wherein the first anode is arranged between the cathode and the aligner. The second anode is arranged between the first aperture member and a collimator lens that collimates the electron beam.
The electron gun according to claim 1 or 2, wherein the second aperture member passes the electron beam collimated by the collimator lens. The electron gun according to claim 3, wherein the second anode has a plurality of stages of anode portions to which a higher voltage is applied as it approaches the collimator lens. An electron gun that has a first aperture member and emits an electron beam,
A second aperture member through which the electron beam emitted from the electron gun is passed is provided.
The electron gun
The cathode that emits the electron beam and
The first aperture member that allows a part of the electron beam to pass through and shields the remaining electron beam.
A first anode arranged between the cathode and the first aperture member,
A Wehnelt electrode arranged between the cathode and the first anode and to which a negative voltage is applied,
It has a second anode arranged between the first aperture member and the second aperture member through which the electron beam passing through the first anode passes.
The acceleration voltage of the electron beam emitted from the cathode is applied to the second anode.
An electron beam apparatus in which a positive voltage lower than the acceleration voltage applied to the second anode and higher than the negative voltage applied to the Wehnelt electrode is applied to the first anode .

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