JP6966317B2 - Cathode - Google Patents

Description

The present invention relates to a cathode and relates to, for example, the cathode of a beam source used in an electron beam lithography system.

In recent years, with the increasing integration of LSIs, the circuit line width of semiconductor devices has been further miniaturized. As a method of forming an exposure mask (also referred to as a reticle) for forming a circuit pattern on these semiconductor devices, an electron beam (EB: Electron beam) drawing technique having excellent resolution is used.

FIG. 10 is a conceptual diagram for explaining the operation of the variable molding type electron beam drawing apparatus. The variable molding type electron beam lithography system operates as follows. The first aperture 410 is formed with a rectangular opening 411 for forming the electron beam 330. Further, the second aperture 420 is formed with a variable molding opening 421 for molding the electron beam 330 that has 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 passing through the opening 411 of the first aperture 410 is deflected by the deflector and passes through a part of the variable forming opening 421 of the second aperture 420 to a predetermined value. The sample 340 mounted on the stage moving continuously 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 molding opening 421 of the second aperture 420 continuously moves in the X direction. Is drawn to. A method of creating an arbitrary shape by passing both the opening 411 of the first aperture 410 and the variable molding opening 421 of the second aperture 420 is called a variable molding method (VSB method).

In electron beam drawing, an electron gun is used. As the cathode material of the electron gun, lanthanum hexaboride (LaB ₆ ), cerium hexaboride (CeB ₆ ), hafnium carbide (HfC) or the like in a sintered or crystalline form is used. Such cathode material is used as an electron source or emitter in various electron beam devices (eg, lithography devices, scanning electron microscopes (SEMs), transmission electron microscopes (TEMs), etc.). The cathode is created, for example, as a tapered shape with a conical angle or a shape in which the tip (top) of the conical shape is cut into a plane. Then, the side surface portion of the tapered shape is coated with carbon. With such a configuration, the electron emission surface is limited to the upper surface of the cathode, and the emission area can be limited. Attempts have been made to improve the brightness of the electron gun. Then, in order to prevent corrosion of the edge of the electron emission surface that comes into contact with the carbon coating due to the chemical interaction between the carbon coating and the LaB ₆ or CeB _{6 cathode material, between the cathode material and the carbon coating.} A structure for providing a gap has been proposed (see, for example, Patent Document 1).

Here, since the cathode evaporates with use, the electron emitting surface gradually recedes. On the other hand, since the carbon coating material does not recede, the isobaric lines are bent by the protrusion of the carbon coating material, and the emitted electrons are emitted. As a result, there is a problem that the brightness is lowered and the life is shortened.

Japanese Unexamined Patent Publication No. 2012-069364

Therefore, one aspect of the present invention provides a cathode capable of suppressing the emission of emitted electrons and extending the period during which the desired brightness can be maintained.

The cathode of one aspect of the present invention is
A single crystal electron emitting member having an electron emitting surface open in one direction,
Same as the electron emitting member, which has an annular surface having a work function larger than that of the electron emitting surface formed so as to surround the periphery of the electron emitting surface on substantially the same surface as the electron emitting surface and surrounds at least the upper side surface of the electron emitting member. The enclosing member formed of the material and
A guide portion that surrounds the lower side surface of the electron emitting member and the entire side surface of the surrounding member, and the height position on the upper surface side is not lower than the height position of the annular surface of the surrounding member.
It is characterized by being equipped with.

Further, the electron emission surface is preferably a (100) crystal plane.

Further, the annular plane is preferably a (111) crystal plane.

Further, it is preferable to further provide a guide portion that covers the side surface of the electron emitting member and the side surface of the surrounding member.

Further, it is preferable that the height position of the surface of the guide portion on the annular surface side is the same as the height position of the annular surface or a position higher than the height position of the annular surface.

According to one aspect of the present invention, it is possible to suppress the emission of emitted electrons and extend the period during which the desired brightness can be maintained.

It is sectional drawing which shows an example of the structure of the cathode in Embodiment 1. FIG. It is a figure for demonstrating the time-dependent change of electron emission in the comparative example of Embodiment 1. FIG. It is a figure for demonstrating the time-dependent change of electron emission in Embodiment 1. FIG. It is a figure which shows an example of the cross-sectional structure of the upper part of a cathode in Embodiment 1. FIG. It is sectional drawing which shows the manufacturing process of the cathode in Embodiment 1. FIG. It is a figure which shows an example of the relationship between the current density and the temperature in the case where the electron beam is emitted using the cathode in Embodiment 1. FIG. It is sectional drawing which shows an example of the structure of the cathode in the modification of Embodiment 1. FIG. It is a conceptual diagram which shows the structure of the drawing apparatus which mounted the cathode in Embodiment 1. FIG. It is a conceptual diagram for demonstrating each area in Embodiment 1. FIG. It is a conceptual diagram for demonstrating operation of a variable molding type electron beam drawing apparatus.

Embodiment 1.
FIG. 1 is a cross-sectional view showing an example of the configuration of the cathode according to the first embodiment. FIG. 1A shows a top view of a portion other than the cathode holder 301. FIG. 1B shows a cross-sectional view of a portion other than the cathode holder 301. In FIGS. 1A and 1B, the cathode 300 is fixed on the cathode holder 301. The cathode 300 includes a cathode main body 20 (the cathode main body is also referred to as an "emitter"), a surrounding member 30, and a guide portion (side cover portion) 40. For the cathode body 20 (electron emission member), it is preferable to use any single crystal _{of lanthanum hexaboride (LaB 6} ) or cerium hexaboride (CeB _{6) as a material.} The lower portion of the cathode body 20 is formed in a columnar shape, for example, the upper portion is formed in a columnar shape having a smaller diameter than the lower portion. The cathode body 20 is a single crystal electron emitting member having an electron emitting surface open in one direction. Specifically, the upper end surface 22 (top) of the upper part of the cathode body 20 forms an electron emission surface processed into a flat surface. The tip upper surface 22 which is an electron emission surface is processed so as to be a (100) crystal plane. In the examples of FIGS. 1A and 1B, the cathode main body 20 has an electron emission surface limited to the upper surface by the surrounding member 30 and the guide portion 40.

The surrounding member 30 is formed in a hollow columnar shape (annular shape). The surrounding member 30 surrounds at least the upper side surface of the cathode body 20. In the example of FIG. 1B, it is arranged on the lower part of the cathode body 20 so as to cover the entire side surface of the upper part of the cathode body 20. It is preferable that the surrounding member 30 has a gap G between it and the upper side surface of the cathode body 20. The gap G is preferably in the range of, for example, about 1 μm to about 15 μm, but the gap can be further reduced or further increased depending on the application. Alternatively, the surrounding member 30 may be arranged in contact with the upper side surface of the cathode body 20. Then, the annular upper surface 32 (top, annular surface) at the tip of the surrounding member 30 is formed into a flat surface so as to be substantially the same surface (substantially the same surface) as the tip upper surface 22 (electron emission surface). In other words, the annular upper surface 32 is formed so as to surround the periphery of the tip upper surface 22 (electron emission surface) on substantially the same surface as the tip upper surface 22 (electron emission surface). As the material of the surrounding member 30, the same material as that of the cathode body 20 is used. However, the annular upper surface 32 of the surrounding member 30 is processed so as to have a larger work function than the tip upper surface 22 (electron emission surface) on the center side. For example, the annular upper surface 32 is processed so as to be a (111) crystal plane.

The guide portion 40 covers the side surface of the cathode body 20 (electron emission member) and the side surface of the surrounding member 30 so as to surround the side surface thereof. The guide portion 40 is arranged in contact with the side surface of the cathode body 20 (electron emission member) and the side surface of the surrounding member 30. Alternatively, they may be arranged with a slight gap between all or part of them. The height position of the upper surface 42 on the annular surface side of the guide portion 40 is formed so as not to be lower than the height position of the annular surface 32 of the surrounding member 30. In other words, it is formed so as to be at the same position as the height position of the annular surface 32 or higher than the height position of the annular surface 32. It is more preferable to form them so as to be on the same surface. As a result, the side surface of the cathode body 20 (electron emission member) and the side surface of the surrounding member 30 can be prevented from being opened. As a result, the emission of electrons can be limited to the above-mentioned tip upper surface 22 (electron emission surface). It is preferable to use carbon (C), tungsten (W), or the like for the guide portion 40 as a material.

FIG. 2 is a diagram for explaining the time course of electron emission in the comparative example of the first embodiment. FIG. 2A shows an example of the state of electrons emitted from the cathode of the comparative example in the state at the start of use. In the comparative example, the cathode 620 is created, for example, as a tapered shape with a conical angle or a shape in which the tip (top) of the conical shape is cut into a plane 622. Then, the side surface portion of the tapered shape is coated with carbon 630. With such a configuration, the electron emission surface is limited to the plane 622 on the upper surface of the cathode, and the emission area can be limited. Attempts have been made to improve the brightness of the electron gun. Then, an acceleration voltage was applied between the cathode 620 and the anode electrode (not shown above) arranged on the downstream side (upper in FIG. 2A), and a negative bias voltage was applied to the lead-out electrode (Wenert) (not shown). When the cathode 620 is heated in this state, electrons (electron group) are emitted from the cathode 620 and proceed to the anode electrode side. In such a case, since the upper surface 632 of the carbon 630 and the flat surface 622 of the upper surface of the cathode 620 are formed on the same surface, the equipotential line (actually becomes the equipotential surface) is the cathode 620 in the vicinity of the electron emission surface of the cathode 620. It becomes parallel to the plane 622 (electron emission plane) of. Therefore, the electrons can travel in the direction orthogonal to the equipotential lines. On the other hand, FIG. 2B shows an example of the state of electrons emitted from the cathode 630 of the comparative example in the state after the lapse of a predetermined use period. Due to evaporation due to the use of the cathode 630 (heating, etc.), the plane 622, which is the electron emission surface, recedes inward. On the other hand, the upper surface 632 of the coated carbon 630 has a sufficiently slow evaporation rate and is unlikely to recede. As a result, as shown in FIG. 2B, a step is formed between the carbon 630 of the comparative example and the plane 622 which is the electron emission surface. Therefore, the equipotential lines are refracted in the vicinity of the plane 622 and become a curved orbit. Since the electrons travel in the direction orthogonal to the equipotential lines, they do not travel in the direction orthogonal to the plane 622 (electron emission plane), and diverging electrons are generated. As a result, the brightness is lowered and the usage limit (life) as an electron source is exhausted.

FIG. 3 is a diagram for explaining the time course of electron emission in the first embodiment. FIG. 3A shows an example of the state of electrons emitted from the cathode 300 in the state at the start of use. In the first embodiment, the cathode 300 is formed as a shape in which the upper portion of the cathode main body 20 is formed in a columnar shape, for example, and the tip upper surface 22 is cut out in a plane. The side surface of the upper part of the cathode body 20 is surrounded by the surrounding member 30, and the side surface of the surrounding member 30 is surrounded by the guide portion 40. Since the annular upper surface 32 of the surrounding member 30 is formed of a crystal plane having a work function larger than that of the tip upper surface 22 of the cathode 300, electron emission can be suppressed. With such a configuration, the electron emission surface is limited to the tip upper surface 22 of the cathode 300, and the emission area can be limited. This improves the brightness of the electron gun. Then, an acceleration voltage was applied between the cathode 300 and the anode electrode (not shown above) arranged on the downstream side (upper in FIG. 3A), and a negative bias voltage was applied to the lead-out electrode (Wenert) (not shown). When the cathode 300 is heated in this state, electrons (electron group) are emitted from the cathode 300 and proceed to the anode electrode side. In such a case, since the tip upper surface 22 of the cathode body 20, the annular upper surface 32 of the surrounding member 30, and the annular upper surface 42 of the guide portion 40 are formed on substantially the same surface, the tip upper surface 22 (electron emission) of the cathode body 20 is formed. In the vicinity of the surface), the equipotential lines (which are actually equipotential surfaces) are parallel to the upper end surface 22 (electron emission surface) of the cathode body 20. Therefore, the electrons can travel in the direction orthogonal to the equipotential lines.
On the other hand, FIG. 3B shows an example of the state of electrons emitted from the cathode 300 in a state after a predetermined period of use has elapsed. Due to evaporation due to the use of the cathode 300 (heating, etc.), the upper surface surface 22 of the tip, which is the electron emission surface of the cathode body 20, recedes inward. On the other hand, the guide portion 40 formed of carbon or the like has a sufficiently slower evaporation rate than the cathode main body 20, so that a step is formed. However, in the first embodiment, the surrounding member 30 is arranged so as to surround the side surface of the cathode main body 20 by using the same material as the cathode main body 20. Therefore, just as the tip upper surface 22 of the cathode body 20 recedes, the annular upper surface 32 of the surrounding member 30 also recedes at the same speed. Therefore, the upper surface 22 at the tip of the cathode body 20 and the annular upper surface 32 of the surrounding member 30 can continue to be kept in the same plane. Therefore, in the vicinity of the tip upper surface 22 (electron emission surface) of the cathode body 20, the equipotential line (actually the equipotential surface) is kept parallel to the tip upper surface 22 (electron emission surface) of the cathode body 20. Therefore, the electrons can travel in the direction orthogonal to the equipotential lines. Therefore, the limit of use (life) as an electron source can be extended. Even when a gap G is formed between the side surface of the cathode body 20 and the inner wall of the surrounding member 30, electrons are emitted from the side surface of the cathode body 20 because no pulling electric field is generated in the gap G. Even if it does, it only stays in the gap and does not affect the electron beam formation.

FIG. 4 is a diagram showing an example of the cross-sectional configuration of the upper part of the cathode in the first embodiment. Although the cross section is shown in FIG. 4, the diameter D2 of the annular upper surface 32 of the surrounding member 30 is close to the tip upper surface 22 (electron emission surface) of the cathode body 20 with respect to the diameter D1 of the tip upper surface 22 of the cathode body 20. The size is such that the equipotential line (actually the equipotential surface) can continue to be parallel to the upper end surface 22 (electron emission surface) of the cathode body 20. As the upper surface 22 at the tip of the cathode body 20 and the annular upper surface 32 of the surrounding member 30 retreat due to evaporation, the step between the upper surface 42 of the guide portion 40 and the upper surface 42 increases. For example, assuming that such a step is suppressed to within 20% in terms of aspect ratio, it is preferable that the diameter D2 of the annular upper surface 32 is at least twice the diameter D1 of the tip upper surface 22. For example, the diameter D1 of the tip upper surface 22 is preferably about 10 to 100 μm (for example, 50 μm). Further, the diameter D2 of the annular upper surface 32 is preferably about 50 to 200 μm (for example, 100 μm).

FIG. 5 is a cross-sectional view showing the manufacturing process of the cathode according to the first embodiment. As shown in FIG. 5A, first, _{a single crystal member of either lanthanum hexaboride (LaB 6} ) or cerium hexaboride (CeB ₆ ) was used to form a columnar lower portion. For example, the cathode body 20 is processed into a columnar shape in which the upper part has a smaller diameter than the lower part. In that case, processing is performed so that the upper surface side (the surface side forming the electron emission surface) becomes 100 crystal planes. The formed cathode body 20 is fixed on the cathode holder 301. In addition to the (100) plane, it may be formed on a crystal plane such as the (310) plane in which the work function becomes small.

Next, as shown in FIG. 5B, the outer circumference is the same size as the diameter of the lower part of the cathode body 20, and the inner diameter is slightly larger than the diameter of the upper part of the cathode body 20 (fitting size). A member for the hollow cylindrical (annular) surrounding member 30 that is longer than the upper part of the cathode body 20 is formed. In that case, the upper surface (the surface side forming the surface in the same direction as the electron emission surface of the cathode body 20) is processed so as to be the 111 crystal plane. The member for the surrounding member 30 uses the same single crystal as the cathode main body 20 or the single crystal material of the same manufacturing rod, and the cut angle when forming the upper surface side is changed from that of the cathode main body 20 (111). You may cut it out. Alternatively, a material that has been crystal-grown so that the upper surface becomes a (111) crystal plane may be used. In addition to the (111) plane, it may be formed on a crystal plane having a large work function such as the (211) plane. The first embodiment includes a case where the crystal plane on the upper surface side of the member for the surrounding member 30 is formed as a crystal plane having a relatively larger work function than the upper surface of the cathode body 20. Then, a member for the surrounding member 30 is fitted from the upper side of the cathode body 20 to the upper part of the cathode body 20, and the bottom surface of the member for the surrounding member 30 and the cathode body 20 are adhered with an adhesive. As an adhesive, for example, using a mixture of colloidal carbon and B _{4 C,} it can be bonded by sintering after fitting.

Next, as shown in FIG. 5 (c), a hollow cylindrical (annular) guide having an inner diameter slightly larger than the diameter of the lower part of the cathode body 20 (fitting size) and longer than the cathode body 20. The portion 40 is formed. Then, the guide portion 40 is fitted into the surrounding member 30 and the cathode main body 20 from the upper side of the surrounding member 30, and the side surface of the surrounding member 30 and the side surface of the lower portion of the cathode main body 20 are adhered with an adhesive. As an adhesive, for example, using a mixture of colloidal carbon and B _{4 C,} it can be bonded by sintering after fitting.

Next, as shown in FIG. 5D, the upper surface of the built-in structure in which the cathode main body 20, the surrounding member 30, and the guide portion 40 are incorporated is mechanically polished to mechanically polish the upper surface of the tip of the cathode main body 20. The annular upper surface 32 of the surrounding member 30 and the annular upper surface 42 of the guide portion 40 can be formed on the same surface. As described above, the cathode 300 according to the first embodiment is manufactured.

FIG. 6 is a diagram showing an example of the relationship between the current density and the temperature when the electron beam is emitted using the cathode in the first embodiment. In FIG. 6, the vertical axis shows the current density and the horizontal axis shows the heating temperature. As shown in FIG. 6, the current density (part A) of the electron group emitted from the tip upper surface 22 of the cathode body 20 increases as the temperature rises. On the other hand, the current density (part B) of the electron group emitted from the annular upper surface 32 of the surrounding member 30 remains sufficiently lower than that of the cathode body 20 regardless of the increase in temperature. The current density J of the electron beam emitted from the hot cathode has a work function φ, a heating temperature T (cathode temperature), a Boltzmann coefficient k, a Richardson constant A (= 8.62 × 10 ^-5 eV / K), and a transparency. Using the magnetic coefficient η (= 0 to 1), it can be defined by the following Richardson-Dassiman equation (1).
(1) J = η ・ A ・ T ²・ exp {−φ / (k ・ T)}

As can be seen from the results of equation (1) and FIG. 6, the surrounding member formed on the crystal plane having a large work function φ with respect to the upper surface 22 of the tip of the cathode body 20 formed on the crystal plane having a small work function φ. From the annular upper surface 32 of 30, it can be seen that the emission of electrons is sufficiently small even though the materials are the same.

FIG. 7 is a cross-sectional view showing an example of the configuration of the cathode in the modified example of the first embodiment. In FIG. 7, the lower side of the cathode 300 is not shown. In the example of FIG. 7, the upper part of the cathode main body 20 is created, for example, as a tapered shape with a tapered cone angle or a shape (conical cone shape) in which the tip (top) of the conical shape is cut into a plane. Then, the inner peripheral side of the surrounding member 30 is processed into a tapered shape so as to be parallel to the tapered side surface of the upper portion of the cathode main body 20. Other configurations are the same as those in FIG. As in the modified example of FIG. 7, the shape of the upper part of the cathode main body 20 in the first embodiment is not limited to a cylinder, and may be another shape.

FIG. 8 is a conceptual diagram showing a configuration of a drawing apparatus equipped with a cathode according to the first embodiment. In the example of FIG. 8, the case where the cathode according to the first embodiment is mounted as the electron source of the drawing apparatus 100 is shown. However, the cathode in the first embodiment is not limited to the drawing device which is a lithography device, and is an electron source or an emitter in various electron beam devices (for example, a scanning electron microscope (SEM), a transmission electron microscope (TEM), etc.). Can be used as. In FIG. 8, the drawing apparatus 100 includes a drawing mechanism 150 and a control system circuit 160. The drawing device 100 is an example of a charged particle beam drawing device equipped with a cathode 300. In the example of FIG. 8, a variable molding type (VSB type) drawing apparatus is shown as an example. The drawing device 100 is not limited to a configuration using a single beam such as a VSB type, and may be a configuration using a multi-beam. The drawing mechanism 150 includes an electron gun mechanism 230, an electronic lens barrel 102, and a drawing chamber 103. An electron gun 201 is arranged in the electron gun mechanism 230. In the electronic lens barrel 102, an electronic lens 211, an illumination lens 202, a blanking deflector 212, a first molded aperture substrate 203, a projection lens 204, a deflector 205, a second molded aperture substrate 206, an objective lens 207, A main deflector 208 and a sub-deflector 209 are arranged. An XY stage 105 is arranged in the drawing chamber 103. A sample 101 such as a mask to be drawn is arranged on the XY stage 105 at the time of drawing. The sample 101 includes an exposure mask for manufacturing a semiconductor device. In addition, the sample 101 contains mask blanks coated with resist and not yet drawn. For example, a pair of electrodes is used as the blanking deflector 212.

Further, the electron gun 201 has a cathode 300, a Wehnelt 322, and an anode 324 according to the first embodiment. As the cathode 300, for example, a lanthanum hexaboride (LaB ₆ ) crystal or the like is suitable. The Wehnelt 322 is arranged between the cathode 320 and the anode 324. Further, the anode 324 is grounded and the potential is set to the ground potential. The boundary between the electron gun mechanism 230 and the electron barrel 102 is formed so that an electron beam can pass through.

The control system circuit 160 includes a control computer 110, a control circuit 120, and a high-voltage power supply circuit 130. A high voltage power supply circuit 130 is connected to the electron gun 201. The drawing mechanism 150 is controlled by the control circuit 120. The control computer 110 controls the entire drawing device 100.

Here, FIG. 8 describes a configuration necessary for explaining the first embodiment. The drawing apparatus 100 may usually have other necessary configurations. For example, for position deflection, a multi-stage deflector of two stages of main and sub of the main deflector 208 and the sub-deflector 209 is used, but the position is deflected by a one-stage deflector or a multi-stage deflector of three or more stages. It may be the case. Further, an input device such as a mouse or a keyboard, a monitor device, or the like may be connected to the drawing device 100.

FIG. 9 is a conceptual diagram for explaining each region in the first embodiment. In FIG. 9, the drawing region 510 of the sample 101 is virtually divided into a plurality of strip-shaped stripe regions 520, which is the width that can be deflected in the Y direction of the main deflector 208. Further, each stripe region 520 is virtually divided into a plurality of subfields (SF) 530 (small regions) which are the deflectable sizes of the sub-deflector 209. Then, a shot figure 552,554,556 is drawn at each shot position of each SF530.

A digital signal for blanking control is output from the control circuit 120 operated by the control signal from the control computer 110 to a DAC amplifier for blanking control (not shown). Then, in the DAC amplifier for blanking control, the digital signal is converted into an analog signal, amplified, and then applied to the blanking deflector 212 as a deflection voltage. The electron beam 200 is deflected by such a deflection voltage, and the irradiation time (irradiation amount) of each shot is controlled.

A digital signal for main deflection control is output from the control circuit 120 to a DAC amplifier (not shown). Then, in the DAC amplifier for main deflection control, the digital signal is converted into an analog signal, amplified, and then applied to the main deflector 208 as a deflection voltage. The electron beam 200 is deflected by such a deflection voltage, and the beam of each shot is deflected to the reference position of the target SF30 which is virtually divided into a mesh shape.

A digital signal for sub-deflection control is output from the control circuit 120 to a DAC amplifier (not shown). Then, in the DAC amplifier for sub-deflection control, the digital signal is converted into an analog signal, amplified, and then applied to the sub-deflection device 209 as a deflection voltage. The electron beam 200 is deflected by such a deflection voltage, and the beam of each shot is deflected to each shot position in the target SF30.

In the drawing apparatus 100, the drawing process is advanced for each stripe region 520 by using a multi-stage deflector. Here, as an example, a two-stage deflector such as a main deflector 208 and a sub-deflector 209 is used. While the XY stage 105 continuously moves, for example, in the −x direction, drawing proceeds in the x direction for the first stripe region 520. Then, after the drawing of the first stripe area 520 is completed, the drawing of the second stripe area 520 is proceeded in the same manner or in the opposite direction. After that, the drawing of the third and subsequent stripe areas 520 will proceed in the same manner. Then, the main deflector 208 sequentially deflects the electron beam 200 to the reference position of the SF 530 so as to follow the movement of the XY stage 105. Further, the sub-deflector 209 deflects the electron beam 200 from the reference position of each SF 530 to each shot position of the beam irradiated into the SF 530. As described above, the main deflector 208 and the sub deflector 209 have deflection regions of different sizes. Then, the SF 530 is the minimum deflection region in the deflection regions of the plurality of stages of the deflector.

When the cathode 300 is heated while a negative acceleration voltage is applied to the cathode 300 and a negative bias voltage is applied to the Wehnelt 322, electrons (electrons) are emitted from the cathode 300, and the emitted electrons (electrons) are emitted. After forming a convergence point (crossover: CO) (cathode crossover), it spreads and is accelerated by the acceleration voltage to form an electron beam, which travels toward the anode 324. Then, the electron beam passes through the opening provided in the anode 324, and the electron beam 200 is emitted from the electron gun 201.

The electron beam 200 emitted from the electron gun 201 (emission unit) is converged by the electron lens 211 to, for example, a center height position (an example of a predetermined position) in the blanking deflector 212, and a convergence point (crossover:: C.O.) is formed. Then, when passing through the blanking deflector 212 arranged behind the electronic lens 211 in the optical axis direction, the blanking deflector is controlled by a deflection signal from the DAC amplifier 122 for blanking. ON / OFF of the beam is controlled by 212. In other words, the blanking deflector 212 deflects the electron beam when performing blanking control for switching between beam ON and beam OFF. The entire electron beam 200 deflected so as to be in the beam OFF state is shielded by the first molded aperture substrate 203 arranged behind the blanking deflector 212 in the optical axis direction. On the contrary, in the beam ON state, the electron beam 200 is illuminated at a position covering the entire rectangular hole formed in the first molded aperture substrate 203, and a part of the electron beam 200 illuminates the first molded aperture substrate 203. pass. The electron beam 200 that has passed through the first molded aperture substrate 203 from the beam OFF state to the beam ON and then to the beam OFF becomes one shot of the electron beam. The blanking deflector 212 controls the direction of the passing electron beam 200 to alternately generate a beam ON state and a beam OFF state. For example, a voltage of 0 V may be applied (or no voltage is applied) when the beam is ON, and a voltage of several V may be applied to the blanking deflector 212 when the beam is OFF. The irradiation amount per shot of the electron beam 200 irradiated to the sample 101 is adjusted by the irradiation time t of each shot.

The electron beam 200 controlled to turn on the beam illuminates the entire rectangular hole of the first molded aperture substrate 203 by the illumination lens 202. Here, the electron beam 200 is first formed into a rectangular shape. Then, the electron beam 200 of the first aperture image that has passed through the first molded aperture substrate 203 is projected onto the second molded aperture substrate 206 by the projection lens 204. By the deflector 205, the first aperture image on the second molded aperture substrate 206 is deflection controlled, and the beam shape and dimensions can be changed (variable molding is performed). Such variable molding is performed for each shot, and is usually molded into a different beam shape and size for each shot. Then, the electron beam 200 of the second aperture image that has passed through the second molded aperture substrate 206 is focused by the objective lens 207, deflected by the main deflector 208 and the sub-deflector 209, and continuously moves XY. The desired position of the sample 101 placed on the stage 105 is irradiated. In other words, the electron beam of the beam ON is imaged on the sample 101 by the objective lens 207 arranged behind the blanking aperture 214 in the optical axis direction. FIG. 8 shows a case where a multi-stage deflection with two main and sub stages is used for the position deflection. In such a case, the main deflector 208 deflects the electron beam 200 of the corresponding shot while following the stage movement to the reference position of the SF 30, and the sub-deflector 209 deflects the beam of the corresponding shot applied to each irradiation position in the SF. do it. By repeating this operation and connecting the shot figures of each shot, the figure pattern defined in the drawing data is drawn on the sample.

In the first embodiment, since the cathode 300 having a long life and a high brightness is mounted, the drawing process can be continuously performed with a desired brightness.

As described above, according to the first embodiment, it is possible to suppress the emission of emitted electrons and extend the period during which the desired brightness can be maintained. Therefore, it is possible to provide a high-luminance cathode 300 having a long life.

The embodiment has been described above with reference to specific examples. However, the present invention is not limited to these specific examples.

Further, although the description of parts not directly required for the description of the present invention such as the device configuration and the control method is omitted, the required device configuration and the control method can be appropriately selected and used. For example, the description of the control unit configuration for controlling the drawing apparatus 100 has been omitted, but it goes without saying that the required control unit configuration is appropriately selected and used.

In addition, all cathode and electron beam lithography systems that include the elements of the present invention and can be appropriately redesigned by those skilled in the art are included in the scope of the present invention.

20 Cathode body 22 Tip top surface 30 Surrounding member 32 Circular top surface 40 Guide section 42 Circular top surface 100 Drawing device 101,340 Sample 102 Electron lens barrel 103 Drawing room 105 XY stage 110 Control computer 120 Control circuit 130 High-voltage power supply circuit 150 Drawing mechanism 160 Control System circuit 200 Electron beam 201 Electron gun 202 Illumination lens 203 First molded aperture substrate 204 Projection lens 205 Deflector 206 Second molded aperture substrate 207 Objective lens 208 Main deflector 209 Sub-deflector 211 Electronic lens 212 Blanking deflector 230 Electron gun mechanism 300 Cathode 301 Cathode holder 322 Wenelt 324 Cathode 330 Electron beam 410 First aperture 411 Opening 420 Second aperture 421 Variable molding opening 430 Charged particle source 510 Drawing area 520 Striped area 530 SF
552,554,556 Shot figure 620 Cathode 622 Plane 630 Carbon 632 Top surface

Claims (4)

A single crystal electron emitting member having an electron emitting surface open in one direction,
The said, which has an annular surface having a work function larger than that of the electron emitting surface formed so as to surround the periphery of the electron emitting surface on substantially the same surface as the electron emitting surface, and surrounds at least the upper side surface of the electron emitting member. An enclosing member made of the same material as the electron emitting member,
A guide portion that surrounds the lower side surface of the electron emitting member and the entire side surface of the surrounding member, and the height position on the upper surface side is not lower than the height position of the annular surface of the surrounding member.
A cathode characterized by being equipped with. The cathode according to claim 1, wherein the electron emission surface is a (100) crystal plane. The cathode according to claim 1 or 2, wherein the annular plane is a (111) crystal plane. Claims 1 to 3 characterized in that the height position of the surface of the guide portion on the annular surface side is the same as the height position of the annular surface or higher than the height position of the annular surface. The cathode described in any of.

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