JP6139449B2 - Stage device and electron beam device - Google Patents

Description

  The present invention relates to a stage apparatus and an electron beam apparatus.

Conventionally, in an electron beam apparatus such as a scanning electron microscope, a sample to be processed with an electron beam is placed on a stage and moved. Related prior art documents include the following patent documents.
Patent Literature 1 JP 2012-64567 A Patent Literature 2 JP 2010-272586 A Patent Literature 3 JP 2003-115274 JP Patent Literature 4 JP 10-233434 A Patent Literature 5 JP 2007-300132 A

  In the electron beam apparatus, it is preferable that the potential of the sample on the stage can be easily set.

  In the first aspect of the present invention, there is provided a stage device for placing a sample to be processed by an electron beam, an insulating substrate, an electrode for chuck provided on the insulating substrate, and a conductive material on the surface of the insulating substrate. And a support unit potential control unit configured to control the potentials of the plurality of support units.

  According to a second aspect of the present invention, there is provided an electron beam apparatus including the stage apparatus according to the first aspect and an irradiation unit that irradiates a sample with an electron beam.

  The summary of the invention does not enumerate all the features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

It is a figure which shows the structural example of the electron beam apparatus 100 which concerns on embodiment. It is a figure which shows the side surface of the stage apparatus 30 and the sample 200. FIG. FIG. 3 is a diagram showing a surface on the side where a sample 200 is placed in the stage device 30. It is a figure which shows the side surface of the stage apparatus 30 and the sample 200. FIG. FIG. 3 is a diagram showing a surface on the side where a sample 200 is placed in the stage device 30. It is a figure which shows the other structural example of the stage apparatus. It is a figure which shows the other structural example of the stage apparatus. It is a figure which shows the other structural example of the stage apparatus. Equivalent circuit of positive side power source 38-1, negative side power source 38-2, capacitance C1 between sample 200 and positive side power source 38-1, and capacitance C2 between sample 200 and negative side electrode 36-2 FIG. FIG. 4 is a diagram showing a structural example of a support portion 34.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 is a diagram illustrating a configuration example of an electron beam apparatus 100 according to the embodiment. The electron beam apparatus 100 processes the sample 200 by irradiating the sample 200 with an electron beam. The electron beam apparatus 100 of this example is a scanning electron microscope (CD-SEM) for length measurement. However, the electron beam apparatus 100 is not limited to CD-SEM. The electron beam apparatus 100 may be various electron beam apparatuses that place and move a sample on a stage, such as other types of scanning electron microscopes and electron beam exposure apparatuses.

  The electron beam apparatus 100 of this example includes a housing 10, an electron gun 12, a focusing lens 14, a deflection coil 16, an objective lens 18, a detector 20, a beam control unit 22, a signal processing unit 24, a stage control unit 26, and a stage device. 30. The housing 10 seals the electron gun 12, the focusing lens 14, the deflection coil 16, the objective lens 18, the detector 20, the stage device 30, and the sample 200.

  The electron gun 12, the focusing lens 14, the deflection coil 16, and the objective lens 18 function as an irradiation unit that irradiates the sample 200 with an electron beam. The electron gun 12 emits electrons according to the applied energy. A voltage for accelerating electrons in the direction of the stage device 30 is applied to the electron gun 12. The focusing lens 14 is provided in the vicinity of the electron gun 12 and focuses the electrons emitted from the electron gun 12 to form an electron beam.

  The deflection coil 16 controls the deflection direction of the electron beam focused by the focusing lens 14. That is, the deflection coil 16 controls the position where the sample 200 is irradiated with the electron beam. The objective lens 18 controls the focal position of the electron beam focused by the deflection coil 16. For example, the objective lens 18 focuses the electron beam on the surface of the sample 200.

  The beam control unit 22 controls the focusing lens 14, the deflection coil 16, and the objective lens 18. For example, the beam control unit 22 controls the deflection coil 16 to scan the electron beam within a predetermined region on the surface of the sample 200.

  The stage device 30 places and moves the sample 200 to be processed by the electron beam. For example, the stage device 30 is movable in the horizontal direction and the vertical direction. As a result, the approximate position of the sample 200 where the electron beam is irradiated is adjusted. The stage control unit 26 controls the movement of the stage device 30.

  The sample 200 emits secondary electrons when irradiated with an electron beam. The detector 20 detects the secondary electrons emitted by the sample 200 for each electron beam irradiation position (that is, the deflection amount in the deflection coil 16). The signal processing unit 24 forms an image indicating the surface state of the sample 200 according to the secondary electrons detected by the detector 20.

  2A and 2B are diagrams illustrating a configuration example of the stage apparatus 30. FIG. FIG. 2A is a diagram illustrating a side surface of the stage device 30 and the sample 200. FIG. FIG. 2B is a diagram illustrating a surface on the side where the sample 200 is placed in the stage apparatus 30. The stage apparatus 30 includes an insulating substrate 32, a positive electrode 36-1, a negative electrode 36-2, a plurality of support portions 34, a positive power source 38-1, and a negative power source 38-2.

  The insulating substrate 32 is made of an insulating material. The insulating substrate 32 is moved in the horizontal direction and the vertical direction by the stage control unit 26. A positive electrode 36-1, a negative electrode 36-2, and a plurality of support portions 34 are provided on the surface of the insulating substrate 32. In this specification, the surfaces of the members such as the insulating substrate 32 and the sample 200 refer to the surface on the electron gun 12 side, and the back surface refers to the surface on the bottom side of the housing 10.

  The positive side electrode 36-1 and the negative side electrode 36-2 are provided separately from each other and function as chucking electrodes. That is, when a voltage is applied to the positive side electrode 36-1 and the negative side electrode 36-2, charges having opposite polarities are generated on the surfaces of the positive side electrode 36-1 and the negative side electrode 36-2 and the back surface of the sample 200. get together. The sample 200 is adsorbed to the stage device 30 by the electrostatic force of the charge. The stage apparatus 30 of this example has a bipolar chuck electrode, but the stage apparatus 30 is a monopolar chuck in which only one of a positive electrode or a negative electrode is provided on the surface of the insulating substrate 32. You may have an electrode.

  Since the sample 200 is adsorbed by the electrostatic chuck, the electron beam apparatus 100 can prevent slipping while the stage apparatus 30 is moving even if the sample 200 has a relatively small friction coefficient on the back surface. For example, the sample 200 is a mask for EUV (Extreme Ultra Violet) exposure. In this case, the layer 202 exposed on the back surface of the sample 200 is, for example, chromium nitride.

  The positive power supply 38-1 sets a potential with respect to the reference potential of the positive electrode 36-1. The negative power supply 38-2 sets a potential with respect to the reference potential of the negative electrode 36-2. In this example, the reference potential is the ground potential. The positive power source 38-1 and the negative power source 38-2 in this example are connected in series, and a ground potential is applied to the connection point.

  The positive electrode 36-1 and the negative electrode 36-2 are provided exposed on the surface of the insulating substrate 32. That is, a space is provided between the positive electrode 36-1 and the negative electrode 36-2 and the back surface of the sample 200. When the chuck electrode is embedded in the insulating substrate 32, a dielectric is disposed immediately below the sample 200. For this reason, when the dielectric is charged up by an electron beam or the like, the sample 200 cannot be irradiated with the electron beam with high accuracy. In the stage apparatus 30 of this example, a space is provided immediately below the sample 200, and the positive side electrode 36-1 and the negative side electrode 36-2 are provided to be exposed. Does not occur.

  The plurality of support portions 34 are provided on the surface of the insulating substrate 32. Each support part 34 is provided away from each other. The stage apparatus 30 of this example has three support portions 34 as shown in FIG. 2B. In this example, the surface shape of the insulating substrate 32 is a rectangle, and support portions 34 are provided on three sides of the rectangle.

  The plurality of support portions 34 support the sample 200 so that a space is formed between the sample 200 and the positive electrode 36-1 and the negative electrode 36-2. That is, the support part 34 is provided so that the top part of the support part 34 is higher than the surfaces of the positive electrode 36-1 and the negative electrode 36-2. The top portion refers to the surface or point at the highest position in the support portion 34. In the present specification, unless a direction is particularly specified, the height indicates a position in a direction perpendicular to the surface of the insulating substrate 32.

  The support part 34 may be thicker than the positive electrode 36-1 and the negative electrode 36-2. In this example, the support portion 34 has a top area smaller than a bottom area. The top of the support 34 may be approximately a point. Moreover, the front-end | tip part of the support part 34 is formed with an insulating material. For example, the tip is made of sapphire. The distal end portion of the support portion 34 refers to a portion including the top portion that contacts the sample 200 in the support portion 34.

  According to the stage apparatus 30 of this example, since the sample 200 is supported by the plurality of spaced apart support portions 34, the contact area between the stage apparatus 30 and the sample 200 can be reduced, and the generation of particles can be reduced. . In addition, since the sample 200 is attracted to the stage device 30 by the electrostatic chuck, it is possible to prevent slip even on the sample 200 having a small friction coefficient without reducing the moving speed of the stage. For this reason, the throughput is improved. Further, since a space is formed between the sample 200 and the insulating substrate 32 by the support portion 34, the positive electrode 36-1 and the negative electrode 36-2 are exposed and provided on the surface of the insulating substrate 32. it can. Accordingly, it is possible to prevent charge-up immediately below the sample 200 while fixing the sample 200 with the electrostatic chuck.

  Moreover, it is preferable that the support part 34 is arrange | positioned so that the sample 200 may not bend. However, when the electron beam apparatus 100 is a CD-SEM, even if the sample 200 is bent in the vertical direction, the measurement accuracy in the horizontal direction is not affected.

  3A and 3B are diagrams showing another configuration example of the stage apparatus 30. FIG. FIG. 3A shows the side surface of the stage apparatus 30 and the sample 200. FIG. 3B shows the surface on the side where the sample 200 is placed in the stage apparatus 30.

  The stage apparatus 30 of this example further includes a guard ring 40 in addition to the configuration of the stage apparatus 30 shown in FIGS. 2A and 2B. The guard ring 40 is provided so as to surround the positive electrode 36-1 and the negative electrode 36-2. The guard ring 40 is formed away from the positive electrode 36-1 and the negative electrode 36-2. As shown in FIGS. 3A and 3B, the stage apparatus 30 may include one guard ring 40 that collectively surrounds the positive electrode 36-1 and the negative electrode 36-2. You may have the two guard rings 40 which each surround the negative side electrode 36-2.

  A reference potential is applied to the guard ring 40. The reference potential is the same as the reference potential of the positive power supply 38-1 and the negative power supply 38-2. Thereby, the leakage of the electric field which arises by having applied the voltage to the positive side electrode 36-1 and the negative side electrode 36-2 can be suppressed, and an electron beam can be controlled accurately.

  The guard ring 40 is provided exposed on the surface of the insulating substrate 32. The guard ring 40 is provided so as not to contact the sample 200. That is, the height of the guard ring 40 is lower than that of the support portion 34.

  The guard ring 40 of this example is provided between the positive electrode 36-1 and the negative electrode 36-2 and the plurality of support portions 34. In another example, the guard ring 40 may be provided outside the plurality of support portions 34.

  FIG. 4 is a diagram showing another configuration example of the stage apparatus 30. As shown in FIG. The stage apparatus 30 of this example further includes a support unit potential control unit 42 in addition to the configuration of the stage apparatus 30 shown in FIGS. 2A and 2B. In the present example, the plurality of support portions 34 are formed of a conductive material. The support unit potential control unit 42 controls the potential of the plurality of support units 34 with respect to the ground potential. Thereby, the potential of the sample 200 can be set. In this example, the connection point of the positive power supply 38-1 and the negative power supply 38-2 is floating.

  The same potential is set for the plurality of support portions 34 in this example. The support unit potential control unit 42 of this example is a variable power source provided between the ground potential and the plurality of support units 34. In another example, a plurality of support unit potential control units 42 that individually set the potential of each support unit 34 may be provided.

  Each support part 34 does not need to be formed only with a conductive material. The support part 34 may include an insulating material as long as the sample 200 and the support part potential control part 42 can be electrically connected. According to the stage apparatus 30 of this example, the potential of the sample 200 is controlled with a simple configuration by controlling the potential of the support portion 34 while suppressing the generation of particles by supporting the sample 200 by the support portion 34. be able to.

  FIG. 5 is a diagram illustrating another configuration example of the stage apparatus 30. The stage apparatus 30 of this example further includes a guard ring 40 in addition to the configuration of the stage apparatus 30 shown in FIG. The guard ring 40 is the same as the guard ring 40 described in FIGS. 3A and 3B. The support portion potential control unit 42 in this example controls the potential of the guard ring 40 together with the potentials of the plurality of support portions 34. Thereby, the leakage of the electric field can be reduced while setting the potential of the back surface of the sample 200. Note that the support portion potential control unit 42 may separately control the potential of the guard ring 40 and the potentials of the plurality of support portions 34.

  The guard ring 40 and the plurality of support portions 34 may be in contact with each other. The plurality of support portions 34 may be in contact with the outer periphery or inner periphery of the guard ring 40, and may be formed on the surface of the guard ring 40.

  FIG. 6 is a diagram illustrating another configuration example of the stage device 30. The stage apparatus 30 of this example further includes a reference power supply 44 and a power supply control unit 50 in addition to the configuration of the stage apparatus 30 shown in FIGS. 2A and 2B.

  The reference power supply 44 controls the reference potential at the connection point between the positive power supply 38-1 and the negative power supply 38-2. The reference power supply 44 in this example is a variable power supply provided between the connection point and the ground potential. Thereby, the reference potentials of the positive power supply 38-1 and the negative power supply 38-2 can be set. The power supply controller 50 controls the voltage of the reference power supply 44.

  FIG. 7 shows a positive power source 38-1, a negative power source 38-2, a capacitance C1 between the sample 200 and the positive electrode 36-1, and a capacitance between the sample 200 and the negative electrode 36-2. It is a figure which shows the equivalent circuit of C2. Further, the potential of the sample 200 is Va, the voltage of the positive power supply 38-1 is V1, the voltage of the negative power supply 38-2 is V2, and the voltage of the reference power supply 44 is Vos.

The charge Q1 of the capacitor C1 and the charge Q2 of the capacitor C2 are given by the following equations.
Q1 = C1 (Vos + V1-Va)
Q2 = C2 (Va−Vos + V2)
If the sample 200 is not charged up, −Q1 + Q2 = 0. Therefore,
−C1 (Vos + V1−Va) + C2 (Va−Vos + V2) = 0
That means
Va = Vos + (C1V1-C2V2) / (C1 + C2) (1)
It becomes. When C1 = C2 and V1 = V2, Va = Vos.

  The power supply control unit 50 controls the voltage Vos of the reference power supply 44 based on the potential Va to be set for the sample 200. As described above, when C1 = C2 and V1 = V2, the power supply control unit 50 sets the voltage Vos equal to the potential Va to be set for the sample 200 to the reference power supply 44.

  The power supply control unit 50 may control the voltage of the reference power supply 44 based on the capacitance C1 and the capacitance C2. In this case, the power supply control unit 50 may further control the voltage of the reference power supply 44 according to the equation (1) based on the potential Va to be set on the sample 200. The voltages V1 and V2 are known.

  The stage apparatus 30 may further include a measurement unit that measures the capacitance C1 and the capacitance C2. The measurement unit may measure the capacitance C1 and the capacitance C2 when processing a new sample 200. The power supply control unit 50 controls the voltage of the reference power supply 44 based on the measurement result of the measurement unit. The measurement unit may detect the areas of the positive electrode 36-1 and the negative electrode 36-2 and calculate the capacitance C1 and the capacitance C2 based on the areas.

  FIG. 8 is a diagram illustrating a structure example of the support portion 34. The support portion 34 in this example has a tip portion 46 and an adjustment portion 48. The tip 46 comes into contact with the sample 200. The tip portion 46 of this example has a weight shape. The adjustment unit 48 adjusts the height of the distal end portion 46. For example, the adjustment unit 48 adjusts the height of the tip 46 by stacking a plurality of layers. The number of layers of the adjusting portion 48 in each support portion 34 is set so as to adjust the variation in the height of the tip portion 46. Thereby, the sample 200 can be held horizontally.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The order of execution of each process such as operations, procedures, steps, and stages in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 10 ... Case, 12 ... Electron gun, 14 ... Condensing lens, 16 ... Deflection coil, 18 ... Objective lens, 20 ... Detector, 22 ... Beam control part, 24 ... Signal processing unit, 26 ... Stage control unit, 30 ... Stage device, 32 ... Insulating substrate, 34 ... Supporting unit, 36-1 ... Positive electrode, 36-2 ... Negative electrode, 38-1 ... Positive power supply, 38-2 ... Negative power supply, 40 ... Guard ring, 42 ... Supporting part potential control part, 44 ... Reference power supply , 46 ... tip part, 48 ... adjustment part, 50 ... power supply control part, 100 ... electron beam apparatus, 200 ... sample, 202 ... layer

Claims (7)

A stage device for placing a sample to be processed by an electron beam,
An insulating substrate;
An electrode for chuck provided on the insulating substrate;
A plurality of support portions formed of a conductive material on the surface of the insulating substrate and supporting the sample;
A support unit potential control unit that controls the potentials of the plurality of support units ,
The chuck electrode has a positive electrode and a negative electrode separated from each other,
The stage apparatus is
A positive power source for setting the potential of the positive electrode;
A negative power supply for setting the potential of the negative electrode;
A stage apparatus further comprising: The chuck electrode is provided exposed on the surface of the insulating substrate,
The stage device according to claim 1, wherein the plurality of support parts support the sample so that a space is formed between the sample and the chuck electrode. The positive power source and the negative power source are connected in series,
The stage apparatus according to claim 1 , wherein a connection point between the positive power source and the negative power source is floating. The stage apparatus according to claim 1, further comprising a guard ring provided around the chuck electrode on the surface of the insulating substrate. The stage device according to claim 4 , wherein the support part potential control unit controls the potential of the guard ring together with the potentials of the plurality of support parts. A stage apparatus according to any one of claims 1 to 5 ,
An electron beam apparatus comprising: an irradiation unit that irradiates the sample with an electron beam. The electron beam apparatus according to claim 6 , wherein the electron beam apparatus is a CD-SEM.

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