JP7246296B2 - Charged particle beam device and holder - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to a charged particle beam device and a holder, and more particularly to a charged particle beam device having a feeding mechanism for applying a retarding voltage and a holder having a current suppressing element.

In conventional analysis techniques, pattern measurement, defect inspection, image acquisition, and the like of samples such as semiconductor devices are performed using a charged particle beam apparatus such as a scanning electron microscope (SEM). Further, during analysis, the sample is held by the holder, and the holder is placed on the sample table. At that time, there is a technique of applying a retarding voltage to the holder via the sample table.

For example, Patent Document 1 discloses a charged particle beam device equipped with a contact terminal for connecting a sample and ground, and a surface potential meter for measuring the potential of the surface of the sample with respect to the ground. Techniques for applying a retarding voltage have been disclosed.

In addition, Patent Document 2 discloses a charged particle beam apparatus having a power source and a wiring section for applying a retarding voltage to a sample. A technique is disclosed in which a resistor is provided in the wiring portion of the sample as a detection module for the current excited in the sample.

JP 2010-272586 A JP 2005-071775 A

However, in the techniques disclosed in Patent Documents 1 and 2, when the retarding voltage is applied or cut off, when the discharge occurs unintentionally, or when the discharge occurs, the retarding voltage Radiation noise and conduction noise may occur when there is a sudden change in . Then, there is a problem that the controller and the control unit of the charged particle beam device malfunction due to their influence, and in the worst case, there is a problem that parts of the charged particle beam device are damaged.

Therefore, there is a demand for a technology that suppresses abrupt movement of charges in the power supply line and improves the reliability of the charged particle beam device when the retarding voltage is applied. Further, development of a holder that can contribute to suppressing such abrupt movement of charges is desired.

Other problems and novel features will become apparent from the description of the specification and the accompanying drawings.

A brief outline of representative embodiments among the embodiments disclosed in the present application is as follows.

A charged particle beam apparatus according to one embodiment includes a charged particle source, a stage provided inside a sample chamber and having a first electrode, and a holder provided on the stage and capable of holding a sample. a first power source provided outside the sample chamber and capable of supplying a negative voltage; and a first power source provided inside the sample chamber and electrically connected to the first power source and the first electrode. and a first cable. Here, the holder is provided with a first current suppressing element electrically connected to the first electrode.

A charged particle beam apparatus according to one embodiment includes a charged particle source, an electrostatic chuck provided inside a sample chamber and having a first electrode and capable of holding a sample, and A first power supply provided and capable of supplying a negative voltage, and a first cable provided inside the sample chamber and electrically connected to the first power supply and the first electrode. Here, the electrostatic chuck further includes a first current suppressing element provided between the first electrode and the first cable and electrically connected to the first electrode and the first cable. have.

A holder, which is an embodiment, includes a contact area for contacting an electrode of a stage provided inside a charged particle beam device, and a resistance element, a high resistance cable, an inductor or a thyristor provided in the contact area. and a current suppressing element configured by

According to one embodiment, it is possible to improve the reliability of the charged particle beam device. Further, it is possible to provide a holder capable of suppressing abrupt movement of charges in the power supply line when the retarding voltage is applied.

1 is a schematic diagram showing a charged particle beam device according to Embodiment 1. FIG. 1 is a schematic diagram showing a main part of a charged particle beam device according to Embodiment 1; FIG. FIG. 4 is an equivalent circuit diagram showing power lines of a retarding power supply in a study example; 2 is an equivalent circuit diagram showing a power line of the retarding power supply in Embodiment 1. FIG. 4 is a cross-sectional view showing the structure around the holder in Embodiment 1. FIG. FIG. 11 is an equivalent circuit diagram showing a power supply line of a retarding power supply according to Embodiment 2; FIG. 8 is a cross-sectional view showing a structure around a holder in Embodiment 2; FIG. 11 is an equivalent circuit diagram showing a power supply line of a retarding power supply according to Embodiment 3; FIG. 11 is a cross-sectional view showing a structure around an electrostatic chuck in Embodiment 3;

Hereinafter, embodiments of the present disclosure will be described in detail based on the drawings. In addition, in all the drawings for describing the embodiments, members having the same functions are denoted by the same reference numerals, and repeated description thereof will be omitted. In addition, in the following embodiments, the description of the same or similar parts will not be repeated in principle unless particularly necessary.

In addition, in the drawings used in the embodiments, hatching may be omitted or hatched in order to make the drawings easier to see.

Also, although the embodiments have been described in sufficient detail to enable those skilled in the art to practice the disclosure, other implementations and configurations are possible. It should be understood that changes in configuration and structure, and substitution of various elements, are possible without departing from the scope and spirit of the present disclosure. Therefore, the following description should not be construed as being limited to them.

Also, in the description of the embodiments below, an example in which the present disclosure is applied to a scanning electron microscope (SEM) using an electron beam as a charged particle beam device will be shown. However, this embodiment should not be construed as limiting, and the present disclosure can be applied to, for example, an apparatus using a charged particle beam such as an ion beam, or a general observation apparatus.

Also, the X, Y and Z directions described in this application are orthogonal to each other. In this application, the Z direction may also be described as the upward direction or height direction of a structure.

(Embodiment 1)
<Structure of Charged Particle Beam Device 1>
A charged particle beam device 1 according to Embodiment 1 will be described below with reference to FIGS. 1 and 2. FIG. The charged particle beam device 1 is, for example, a scanning electron microscope (SEM), and a critical dimension SEM that is an applied device thereof. A critical dimension SEM is a device specialized for dimensional measurement of fine patterns contained in a sample such as a semiconductor device. FIG. 1 is a schematic diagram for explaining the overall outline of the charged particle beam device 1, and FIG. 2 is a schematic diagram for explaining the main part of the charged particle beam device 1.

Moreover, the sample 10 used in the first embodiment is, for example, a wafer manufactured by semiconductor technology. A wafer includes a semiconductor substrate, a semiconductor element such as a transistor formed on the semiconductor substrate, a wiring layer formed on the semiconductor element, and the like. Further, the state of the sample 10 includes the case where only the semiconductor substrate is present, the case where the semiconductor element and the wiring layer are completed on the semiconductor substrate, and the case where these are in the process of being manufactured.

First, with reference to FIG. 1, the paths and operations when the sample 10 is loaded and unloaded will be described.

The charged particle beam device 1 includes a length-measuring SEM unit 201 and a sample transport unit 202, and a cassette 204 containing one or more samples 10 is installed in a user interface 205 outside the charged particle beam device 1. It is The sample transport unit 202 includes a sample transport robot 203 for transporting the sample 10 between the cassette 204 and the length-measuring SEM unit 201 .

The measuring SEM unit 201 includes a sample chamber 171 and a preparation chamber 172. The sample chamber 171 is provided with an electron optical system 170 and a stage 60 on which a holder 50 holding a sample table 20 can be installed. . The stage 60 is movable in the X, Y and Z directions. Further, the preparation room 172 is provided with a holder transport robot 161 .

The interior of the cassette 204 is filled with an inert gas such as nitrogen, and in the preparation chamber 172, pressure state transitions are repeated like atmospheric pressure and vacuum. Also, the inside of the sample transport unit 202 may be filled with an inert gas such as nitrogen.

Cassettes 204 are manually or automatically loaded into user interface 205 by a user or factory automation system. The user interface 205 may also be called a load port, a cassette stand, or the like. After the cassette 204 containing the sample 10 is placed, the user or the factory's automatic system inputs a process such as dimension measurement and an instruction to a controller (not shown).

The controller performs an operation for carrying the sample 10 into the sample chamber 171 in the critical dimension SEM unit 201 according to the input processing and instructions.

First, the sample 10 is taken out from the cassette 204 by the sample transport robot 203 in the sample transport unit 202 . Next, the sample 10 held by the sample transport robot 203 is carried into the preparation chamber 172 with the opening and closing of the doorway 173 .

A holder 50 is installed on the arm of the holder transfer robot 161 mounted in the preparation room 172 . The sample 10 is mounted on the holder 50 in the preparation chamber 172 and held by the holder 50 .

After the sample 10 is held on the holder 50, the controller commands the preparation chamber 172 to be evacuated. As the doorway 174 is opened and closed, the holder transport robot 161 performs an operation 210 of loading the holder 50 holding the sample 10 into the sample chamber 171 . The loaded holder 50 is placed on the sample table 20 of the stage 60 , and the moving mechanism of the stage 60 moves the stage 60 within the field of view of the electron optical system 170 . The above controller controls the electron optical system 170 via the control unit 101 (see FIG. 2), thereby performing dimension measurement of the pattern of the sample 10 and acquiring analysis data such as an SEM image of the sample 10. .

After the desired dimension measurement is performed, the sample 10 is carried out by the reverse procedure of the above description. The holder 50 is separated from the stage 60 and carried out from the sample chamber 171 to the preparation chamber 172 by the operation 210 of the holder conveying robot 161 . After the preparation chamber 172 is opened to the atmosphere, the sample 10 mounted on the holder 50 is taken out by the sample transport robot 203 and stored in the cassette 204 .

Processing of the next sample 10 or the next cassette 204 is then performed by a similar procedure. A critical dimension SEM is used as an in-line device for processes in a semiconductor factory that operates 24 hours a day, 365 days a year. Therefore, the charged particle beam device 1 is required to have high performance in terms of availability, reliability, and the like.

The configuration of the length-measuring SEM unit 201, which is part of the charged particle beam device 1, will be described with reference to FIG.

First, an outline of the configuration and operation of the electron optical system 170 will be described. It should be noted that the content described here is an example of the basic configuration, and some parts are omitted from illustration and description. Therefore, electron optical system components, lenses, and the like mounted in the electron optical system 170 to realize various functions may be added, deleted, or replaced in FIG.

An electron beam (primary electron beam, charged particle beam) EB1 emitted from an electron source (charged particle source) 110 and accelerated by an electron optical system electrode (not shown) is directed over the sample 10 by a scanning deflector 113. Scanned in one or two dimensions. At this time, the electron beam EB1 is converged by the electron lens 114 and irradiated onto the sample 10 . When irradiating the sample 10 , the electron beam EB<b>1 is decelerated by a retarding voltage 31 that is a negative voltage applied to the holder 50 .

When the sample 10 is irradiated with the electron beam EB1, charged particles such as secondary electrons and reflected electrons are emitted from the irradiated location. The emitted charged particles are accelerated toward the electron source 110 by the acceleration action based on the retarding voltage 31 applied to the sample 10, collide with the conversion electrode 111, and generate secondary electrons EB2. Secondary electrons EB2 emitted from conversion electrode 111 are captured by detector 112 . The amount of captured secondary electrons EB2 changes the output of the detector 112, which determines the brightness of each pixel in the SEM image.

For example, when forming a two-dimensional image, the image of the scanning area is formed by synchronizing the control signal of the scanning deflector 113 and the output of the detector 112 . For example, when analyzing a photoresist pattern on the sample 10, the length measurement SEM obtains an SEM image of the photoresist pattern, and automatically measures the width of the photoresist pattern from the grayscale signal of the SEM image.

Control of the electron optical system 170 and formation of SEM images are controlled by control signals from the control unit 101 . A plurality of controllers and power supplies are mounted in the control unit 101 according to the number required for various uses. The control unit 101 is controlled by the controller of the user interface 205 shown in FIG. By the above controller, FAPC (Factory Automation PC) or an information terminal having a monitor that can be visually checked, displays the information, communicates between controllers, or communicates with the factory automation system.

In addition, the stage 60 includes a sample table 20 on the outermost surface on the electron source 110 side. It is electrically connected to the charging power supply 30 . That is, the stage 60 is electrically connected to the retarding power supply 30 . Therefore, the retarding voltage 31 can be applied to the holder 50 and the sample table 20 via the stage 60 on which the holder 50 can be installed.

The vacuum high voltage cable 40 , the connector 46 , the atmosphere high voltage cable 41 and the retarding power supply 30 are included in the length measurement SEM unit 201 , but the vacuum high voltage cable 40 is provided inside the sample chamber 171 . , the atmospheric high-voltage cable 41 and the retarding power supply 30 are provided outside the sample chamber 171 . The connector 46 is made of ceramic or the like and attached to the wall surface of the sample chamber 171 . In addition, the connector 46 is connected to the end of the high voltage cable for vacuum 40 and the end of the high voltage cable for atmosphere 41 so as to electrically connect the inside and outside of the sample chamber 171 .

Here, the method of applying the retarding voltage 31, which is a negative voltage, to the sample 10 via the holder 50 is called a retarding method.

In the scanning electron microscope, the retarding method is a method of obtaining high resolution by decelerating the electron beam EB1 having an acceleration voltage higher than the final acceleration voltage just before the sample 10. FIG. Using the retarding method enables high-resolution observation of the sample 10 at an extremely low accelerating voltage. Advantages of this are that, in addition to being able to improve the resolution at low acceleration, the fine state of the outermost surface of the sample 10 can be observed, and the sample 10, which is sensitive to damage caused by the electron beam EB1, can be observed. .

Although the retarding method is adopted for these advantages, it is necessary to apply a retarding voltage 31, which is a relatively large negative voltage, to the sample 10 for this purpose. Such a retarding voltage 31 is, for example, a voltage of minus several kV.

The retarding voltage 31 is generated inside the retarding power supply 30 and output to the outside of the retarding power supply 30 . The output retarding voltage 31 is introduced into the sample chamber 171 via the atmospheric high voltage cable 41 and the connector 46 . Inside the sample chamber 171 , the retarding voltage 31 is applied to the sample table 20 of the stage 60 via the high voltage cable 40 for vacuum. The vacuum high-voltage cable 40 is wired to the stage 60 so as to withstand movement of the stage 60 .

The step of applying the retarding voltage 31 to the sample 10 is started when the holder 50 is placed on the sample table 20 of the stage 60 and the stage 60 moves to the field of view for acquiring the SEM image. At this time, the retarding voltage 31 is applied to the holder 50, and the potential of the holder 50 changes from the reference potential to the retarding potential.

Conversely, the step of cutting off the retarding voltage 31 from the sample 10 is performed until the holder transport robot 161 unloads the holder 50 after the work such as acquisition of the SEM image is completed. At this time, the retarding voltage 31 is cut off and the potential of the holder 50 is returned to the reference potential. After that, the holder 50 is transported to the preparation chamber 172 .

When analyzing the sample 10 inside the sample chamber 171, the sample 10 is irradiated with the electron beam EB1 emitted from the electron source 110, and the retarding voltage 31 is applied to the holder 50 and the sample table during the irradiation period of the electron beam EB1. The voltage is applied to the holder 50 via the contact portion (contact portion) with 20 . By applying the retarding voltage 31 to the holder 50, the retarding voltage 31 is also applied to the sample 10 integrated with the holder 50 as described above, and the surface of the sample 10 becomes the retarding potential. The contact portion is shown as a contact portion 301 in an equivalent circuit diagram such as FIG. 3 or FIG. 4 which will be described later.

Here, since a high vacuum must be maintained inside the sample chamber 171, it is necessary to make the capacity as small as possible. Normally, the retarding power supply 30 is mounted inside the length measurement SEM unit 201 and provided outside the sample chamber 171 . For this reason, the power supply line of the retarding power supply 30 generally tends to be long.

<Power supply line of the retarding power supply 30 in the study example and its problem>
FIG. 3 is an equivalent circuit diagram in an example examined by the inventors of the present application, and is an equivalent circuit diagram showing the power supply line of the retarding power supply 30. As shown in FIG.

The retarding power supply 30 has a retarding voltage 31 , an output capacitor 32 of the retarding power supply 30 such as a bypass capacitor, and an output current suppressing element 33 of the retarding power supply 30 .

In the power supply line of the retarding power supply 30, the equivalent circuit of the high voltage cable 41 for atmosphere and the high voltage cable 40 for vacuum is composed of a cable resistance component 42, a cable inductive component 43, a cable resistance component 44, and a cable resistance component 44. is indicated by the capacitive component 45 . Here, the cable capacitive component 45 is the total stray capacitance of the power supply line of the retarding power supply 30 including the atmospheric high voltage cable 41, the vacuum high voltage cable 40, the connector 46, and the like. Actually, small stray capacitances exist at various points on the power supply line of the retarding power supply 30, and the capacitive component 45 of the cable includes such small stray capacitances.

On the power line of the retarding power source 30 , the sample table 20 (stage 60 ) has a contact portion 301 to which the power line of the retarding power source 30 and the holder 50 are connected. An equivalent circuit of the holder 50 in the power line of the retarding power supply 30 can be represented by a capacitive component 51 of the holder 50 . Similar to the capacitive component 45 of the cable, actually small stray capacities exist at a plurality of locations, and the sum of them is shown here as the capacitive component 51 of the holder 50 .

Thus, when viewed from the retarding power supply 30, the holder 50 on which the sample 10 is placed can be considered as a capacitive load. Therefore, the retarding power supply 30, which is a high-voltage power supply that outputs minus several kV, does not require a large current. Furthermore, for the purpose of preventing rush current, an output current suppressing element 33 is mounted on the output side.

This output current suppressing element 33 is very important. Even if a person is electrocuted, the output current suppressing element 33 has a function of limiting the current value to a safe range. In addition, since the retarding voltage 31 is a high voltage, the output current suppressing element 33 also has a function of suppressing abrupt changes in transient response during voltage application and cutoff. Furthermore, the output current suppressing element 33 also has a function of suppressing the influence of electrostatic induction and the like in order to alleviate the generation of a large electric field during the movement of the stage 60 .

When the retarding voltage 31 changes abruptly, it is accompanied by rapid charge transfer (current), and this abrupt change can be considered as a step response or an impulse response. As can be seen from the Fourier transform of these responses, the point of change contains many high-frequency components, and the high-frequency components may be propagated into space as radiation noise. In addition, high-frequency components are transmitted as conduction noise through the stray capacitance contained in the capacitive component 45 of the cable, the capacitive component 51 of the holder 50, etc. may be propagated to

Low voltage or low current circuits are more susceptible to such radiated or conducted noise. In addition, depending on conditions such as resonance, each noise may become large at a specific location, which may cause malfunction of the controller in the control unit 101 or, in the worst case, damage to electronic components. There is This may adversely affect the performance of the charged particle beam device 1 and reduce the reliability of the charged particle beam device 1 . The output current suppressing element 33 is also important for preventing them.

However, as described above, the atmospheric high-voltage cable 41 and the vacuum high-voltage cable 40 of the power supply line of the retarding power supply 30 are unavoidably long due to the configuration of the charged particle beam device 1 . Therefore, the capacitive component 45 of the cable cannot be ignored. In that case, it is difficult to achieve the above-described expected effects simply by including the output current suppressing element 33 in the retarding power supply 30, which is the supply source.

For example, in the actual measurement of the device, the relationship between the capacitive components is "the capacitive component 51 of the holder 50<the capacitive component 45 of the cable", and the ratio of each capacitive component is "the capacitive component 51 of the holder 50: the capacitive component 45 of the cable. = 1:2".

As described above, the capacitance component 45 (electrostatic capacitance C) of the cable increases depending on the length of the cable, etc., and the retarding voltage 31 (voltage V) is also as high as minus several kV. The charge Q stored in component 45 becomes very large.

In a state in which the retarding voltage 31 is applied, that is, in a state in which charges are accumulated in the capacitive component 45 of the cable, and in a state in which the capacitive component 51 of the holder 50 is empty (zero state), the sample table 20 and the holder 50 contact at the contact portion 301 , the charge accumulated in the capacitive component 45 of the cable abruptly moves to the capacitive component 51 of the empty holder 50 . This means that the current flows steeply, and that the retarding voltage 31 changes steeply. That is, this means that the reliability of the charged particle beam device 1 may deteriorate.

Further, when the retarding voltage 31 is cut off, the holder 50 is brought into contact with the holder transport robot 161 at the reference potential in a state where the capacitance component 51 of the holder 50 or the capacitance component 45 of the cable remains charged. Then, abrupt charge transfer may occur. Therefore, similarly to the above, the reliability of the charged particle beam device 1 may deteriorate.

When a sudden movement of charge occurs, that is, when a steep current flows, the resistance component 42 of the cable and the inductive component 43 of the cable may appear as a large voltage. At the same time, the retarding voltage 31 undergoes a sharp change.

This sharp change in the power supply line may occur unintentionally other than when the retarding voltage 31 is applied and cut off. This is the case where discharge such as creeping discharge or space discharge occurs between the power supply line of the retarding power supply 30 and the reference potential of the chamber, frame, etc. that constitute the sample chamber 171 . These discharges occur, for example, when foreign matter is mixed with the sample 10 . In this case, a large electric field concentration occurs around the foreign matter, or the foreign matter itself becomes a carrier, causing a dielectric breakdown, and the dielectric breakdown causes discharge to occur.

In addition, various materials and various chemicals are used in the semiconductor manufacturing process, and various substances are included in the film and pattern shape forming the sample 10 . Therefore, when the sample 10 is carried into the high-vacuum sample chamber 171, gas may be generated from the sample 10 unintentionally. The gas is not necessarily generated in the preparation chamber 172 , and the gas may be generated in the sample chamber 171 . Even if gas is generated from the sample 10, the degree of vacuum is locally reduced, and the creepage distance or the spatial distance becomes unbearable, and discharge may occur. Here, Paschen's law is empirically known that a low-vacuum state is a state in which discharge is more likely to occur than a high-vacuum state or an atmospheric state.

During discharge, a current flows through the frame or cable of the sample chamber 171, which should not normally flow, and electromagnetic waves, which are radiation noise, also fly around due to the energy generated during discharge. The impact of this discharge becomes greater when it is accompanied by movement of many charges. When a discharge occurs, the electric charges stored in the capacitive component 51 of the holder 50 and the capacitive component 45 of the cable are discharged at once, so that with the impact of the discharge, a steep voltage change similar to that described above occurs, resulting in radiation noise. Or conduction noise is generated. Therefore, the reliability of the charged particle beam device 1 may decrease due to the influence of the discharge.

<Power supply line of retarding power supply 30 in Embodiment 1>
The inventors of the present application have taken into consideration the problems of the above examination examples and devised a power supply line that connects the retarding power supply 30 and the holder 50 . FIG. 4 shows an equivalent circuit diagram of the power supply line of the retarding power supply 30 according to the first embodiment.

Each configuration of the power supply line shown in FIG. 4 is substantially the same as each configuration of the power supply line shown in FIG. 3 of the study example, but the configuration of the holder 50 is different from the study example. Therefore, in the following description, the description of the configuration other than the holder 50 is omitted.

The holder 50 has a contact region CR for contacting the electrode of the sample table 20 (stage 60), and the contact region CR is provided with a current suppressing element CSE. Here, the current suppressing element CSE is a resistive element, a high resistance cable, an inductor, a thermistor, or the like. In Embodiment 1 as well, the retarding voltage 31 is applied and cut off via the contact portion 301 between the sample table 20 and the holder 50 . When the current suppressing element CSE is a resistance element or a high resistance cable, the conductive material contained in the resistance element or high resistance cable is higher than the conductive material contained in the high voltage cable 40 for vacuum and the high voltage cable 41 for atmosphere. , has a high sheet resistance.

Along with the operation 210 of loading the holder 50, the retarding voltage 31 is applied to the holder 50 via the sample table 20 and the current suppressing element CSE, and the retarding voltage 31 gradually increases. Since the retarding voltage 31 is a negative voltage here, the retarding voltage 31 actually drops gradually. Hereinafter, increasing the retarding voltage 31 is expressed as "drop", and decreasing the retarding voltage 31 is expressed as "increase".

When the retarding voltage 31 reaches the target potential, the SEM image is finally obtained while the retarding voltage 31 is applied to the holder 50 via the current suppressing element CSE.

When the holder 50 is carried out after the acquisition of the SEM image and the pattern measurement process are completed, the retarding voltage 31 is is gradually raised, and after the holder 50 reaches the reference potential, the holder 50 is carried out by the holder carrying robot 161 .

Here, when the current suppressing element CSE is a resistive element or a high-resistance cable, the current suppressing element CSE has a relationship of an RC low-pass filter with the capacitive component 51 of the holder 50. Therefore, depending on the RC time constant, The retarding voltage 31 becomes slowly applied. That is, when the charge accumulated in the capacitive component 45 of the cable flows into the capacitive component 51 of the holder 50, or when the charge accumulated in the capacitive component 51 flows into the capacitive component 45 of the cable, the current suppressing element CSE It suppresses the rapid movement of these charges.

Further, when the current suppressing element CSE is an inductor, the current suppressing element CSE has a relationship of a low-pass filter of the capacitive component 51 of the holder 50 and the LC, so the current suppressing element CSE has the function of suppressing the current. have. The inductor has a function of preventing rapid movement of electric charges and a function of blocking high-frequency noise. Therefore, the inductor can suppress the current in a transient response such as a sharp change and conduct the current in the steady state. Note that the inductor is configured by a coil that can be formed by winding a conductive material. Therefore, an inductor can also be formed by winding a metal wire in vacuum to any shape or any constant.

Also, when the current suppressing element CSE is a thermistor, the same effect as an inductor can be expected, so it is desirable to select the optimum current suppressing element CSE according to the system.

When an unintended discharge occurs in the sample 10 or the holder 50, the charges accumulated in the capacitive component 51 of the holder 50 are discharged. However, since the retarding voltage 31 is applied to the holder 50 via the current suppressing element CSE, the current is suppressed, the rapid discharge of the charge from the capacitive component 45 of the cable is suppressed, and the impact of the discharge is reduced. be.

Since the holder 50 is moved into the field of view of the electron optical system 170 in the period from when the holder 50 is carried into the sample chamber 171 to when the SEM image is acquired, there is a little time from an electrical point of view. Within that time range, the retarding voltage 31 can be gradually changed to the target potential, and the retarding voltage 31 can be applied to the holder 50 . The same is true when cutting off the retarding voltage 31 .

In order to reduce the effects of transient response when the retarding voltage 31 is applied or cut off, and to prevent sudden changes in the electric field, the control unit 101 gradually increases or decreases the retarding voltage 31 according to the program. Let However, although the contact portion 301 between the holder 50 and the sample table 20 is the same in principle as the mechanical switch, due to its mechanical structure, it is very rare that the contact fails or chattering occurs. There is a possibility that a situation in which detachment and detachment are repeated like this may occur. In such a case, even if the retarding voltage 31 is gradually changed as described above, the expected effect may not be exhibited.

Further, for example, even if the retarding voltage 31 is gradually lowered when the retarding voltage 31 is cut off, if there is a place where the charge is unintentionally accumulated, the charge remains. There is a possibility that the holder 50 and the sample table 20 will come into contact with each other in this state. In that case, as in the case described above, abrupt charge movement may occur. In addition, when an irregular situation such as discharge occurs, it is not possible to prevent abrupt movement of charges only by gradually changing the program.

Considering the above, in Embodiment 1, the program of the control unit 101 is the same as before, but a mechanical structure is added. That is, the current suppressing element CSE is added to the contact region CR of the holder 50 .

<Structure of Holder 50 Equipped with Current Suppressing Element CSE>
FIG. 5 is a cross-sectional view showing the structure around holder 50 in the first embodiment.

In Embodiment 1, the surface of the stage 60 (the surface of the sample table 20) is provided with an electrode EL for contacting the current suppressing element CSE. The electrode EL is electrically connected to a vacuum high voltage cable 40 . The electrode EL is also surrounded by an insulating layer IL so that the electrode EL is electrically isolated from the surrounding sample table 20 .

A part of the stage 60 constitutes a transport path A1 for transporting the holder 50 . Although not shown here, the stage 60 is provided with guide members such as rails and bearings along the transport path A1.

A part near the bottom surface of the holder 50 constitutes a contact region CR for contacting the electrode of the sample table 20 (stage 60), and the contact region CR is provided with a current suppressing element CSE. A contact portion 301 in the equivalent circuit of FIG. 4 corresponds to a contact (contact surface) between the electrode EL and the current suppressing element CSE in the contact region CR. Moreover, in order to minimize the stray capacitance, it is desirable that the current suppressing element CSE be integrated with the holder 50 .

Also, the current suppressing element CSE may be provided inside the holder 50 instead of on the bottom surface of the holder 50 . For example, the contact region CR is provided with a current suppressing element CSE and a holder electrode provided closer to the bottom surface of the holder 50 than the current suppressing element CSE. It may be electrically connected via the holder electrode and the electrode EL.

The holder 50 moves along the transport path A<b>1 of the stage 60 by the loading or unloading operation 210 . At the time of loading, the retarding voltage 31 is applied to the holder 50 via the current suppressing element CSE until the holder 50 moves along the transport path A1 and is fixed to the stage 60 . Further, in a state where the holder 50 is fixed to the stage 60, the electrode EL of the stage 60 and the current suppressing element CSE provided in the contact region CR of the holder 50 are in contact with each other.

At the time of unloading, an operation opposite to that at the time of loading is performed. During the period before the holder 50 is separated from the stage 60, the retarding voltage 31 is applied to the holder 50 via the current suppressing element CSE.

When analyzing the sample 10 inside the sample chamber 171 , the analysis is performed with the holder 50 fixed to the stage 60 . During the irradiation period of the electron beam EB1, a retarding voltage 31 is applied to the holder 50 from the retarding power supply 30 via the atmospheric high voltage cable 41, the vacuum high voltage cable 40, the electrode EL and the current suppressing element CSE. be done.

In order to reduce the influence of the capacitive component 45 of the cable shown in FIG. As shown in FIG. 5, by providing the current suppressing element CSE in the contact region CR of the holder 50, the influence of the capacitive component 45 of the cable can be reduced. Therefore, when the retarding voltage 31 is applied, it is possible to suppress abrupt movement of charges in the power supply line, and the reliability of the charged particle beam device 1 can be improved.

Further, since the electrode EL is provided on the transport path A1 of the stage 60 and the current suppressing element CSE is provided on the bottom surface of the holder 50, it is easy to secure a contact surface between the electrode EL and the current suppressing element CSE. That is, the area of the contact portion 301 can be increased. For this reason, problems related to poor contact or chattering are less likely to occur, and the retarding voltage 31 can be stably applied to the holder 50 .

(Embodiment 2)
The charged particle beam device 1 according to Embodiment 2 will be described below with reference to FIGS. 6 and 7. FIG. In the following description, differences from the first embodiment are mainly described.

In the second embodiment, as shown in FIGS. 6 and 7, the contact region CR of the holder 50 is provided with a plurality of current suppressing elements CSE1-CSE3. Although three current suppressing elements CSE1 to CSE3 are illustrated here, the number of current suppressing elements may be two or four or more.

Similar to the current suppressing element CSE of Embodiment 1, the current suppressing elements CSE1 to CSE3 are each a resistance element, a high resistance cable, an inductor or a thermistor, but the current suppressing elements CSE1 to CSE3 are different elements. may be the same element. Further, when the current suppressing elements CSE1 to CSE3 are the same element, it is desirable that they have different electrical characteristics.

For example, if the current suppressing elements CSE1-CSE3 are resistive elements or high-resistance cables, respectively, the sheet resistance of the conductive material included in each of the current suppressing elements CSE1-CSE3 is different from each other. The sheet resistance of the conductive material included in each of current suppressing element CSE1 and current suppressing element CSE3 is greater than the sheet resistance of the conductive material included in current suppressing element CSE2.

Since the sheet resistance of the current suppressing element CSE1 is relatively large, the effect of the first contact can be mitigated. Since the sheet resistance of the current suppressing element CSE2 is relatively small, it is possible to easily raise or lower the retarding voltage 31 within a desired time. The relatively high sheet resistance of the current suppressing element CSE3 makes it possible to prepare for unexpected movement of charges such as discharge. The sheet resistance of the current suppressing element CSE1 and the sheet resistance of the current suppressing element CSE3 may be the same or different. By setting the sheet resistance of each of the current suppressing elements CSE1 to CSE3 in this way, it is possible to prevent the reliability of the charged particle beam device 1 from deteriorating.

Further, when the current suppressing elements CSE1 to CSE3 are inductors, the number of turns of the coils in the current suppressing elements CSE1 to CSE3 or the conductive material constituting the coils are different from each other.

Further, when the current suppressing elements CSE1 to CSE3 are thyristors, each thyristor is composed of a semiconductor element such as a diode or a transistor including a p-type semiconductor layer and an n-type semiconductor layer. When the current suppressing elements CSE1 to CSE3 are the semiconductor elements described above, the impurity concentration of the p-type semiconductor layer, the impurity concentration of the n-type semiconductor layer, the width of the p-type semiconductor layer, or the n-type semiconductor layer in the current suppressing elements CSE1 to CSE3 width, etc., are different.

When the holder 50 is loaded, the electrode EL contacts the current suppressing element CSE3, the current suppressing element CSE2, and the current suppressing element CSE1 in this order in accordance with the operation 210. FIG. Further, when the holder 50 is unloaded, the electrode EL contacts the current suppressing element CSE1, the current suppressing element CSE2, and the current suppressing element CSE3 in this order in accordance with the operation 210. FIG. A retarding voltage 31 is applied to the sample 10 on the holder 50 via the electrode EL and the current suppressing elements CSE1 to CSE3.

Also, as in operation 710, the electrode EL of the sample table 20 can be moved along the direction (X direction) along the transport path A1. In that case, the control unit 101 controls which one of the current suppressing elements CSE1 to CSE3 the electrode EL contacts. Thus, the relative positions of the holder 50 and the sample table 20 can change the connection to any of the current suppressing elements CSE1-CSE3, for example using components such as relays, the contact 301 You can also send a signal to to change to any connection. Since the current suppressing elements CSE1 to CSE3 can be selected in this manner, it is possible to more effectively suppress abrupt movement of charges according to the application or the state of the charged particle beam device 1. FIG.

(Embodiment 3)
The charged particle beam device 1 according to Embodiment 3 will be described below with reference to FIGS. 8 and 9. FIG. In the following description, differences from the first embodiment are mainly described.

In the charged particle beam device 1 of the first embodiment, the holder 50 and the sample table 20 are separated, but in the charged particle beam device 1 of the third embodiment, the electrostatic A chuck 80 is used and the sample 10 is mounted on the surface of the electrostatic chuck 80 . Further, in the operation 210 in Embodiment 3, the holder transport robot 161 in the preparation chamber 172 transports only the sample 10 without transporting the holder 50 .

FIG. 8 is an equivalent circuit diagram of the power line of the retarding voltage 31 when the electrostatic chuck 80 is used, and FIG. 9 is a cross-sectional view showing the structure around the electrostatic chuck 80. As shown in FIG.

When the electrostatic chuck 80 is used, the number of electrodes for holding the sample 10 to the holding table increases in order to electrostatically attract the sample 10 . Therefore, in the third embodiment, as shown in FIG. 8, the number of equivalent circuits is increased to two in comparison with the equivalent circuit of FIG. 4 in the first embodiment.

The electrostatic chuck power supply 830 has a retarding voltage 31 and two power supply lines electrically connected to the retarding voltage 31 . The first power supply line has a DC power supply 83 superimposed on the retarding voltage 31 for applying voltage to the electrostatic chuck electrode EL1, an output capacitor 832, and an output current suppressing element 833. The second power supply line has a DC power supply 84 superimposed on the retarding voltage 31 for applying voltage to the electrostatic chuck electrode EL2, an output capacitor 862, and an output current suppressing element 863.

Equivalent circuits such as vacuum high voltage cable 40, atmospheric high voltage cable 41 and connector 46 described in the first embodiment are shown as transmission circuits of cables 840 and 850 in the third embodiment. That is, the resistance component 42, the inductive component 43, the resistance component 44 and the capacitive component 45 included in the vacuum high voltage cable 40, the atmospheric high voltage cable 41, the connector 46, etc. It corresponds to each of the following components included in the second power supply line of the power supply 84 .

Cable 840 (the first power supply line of DC power supply 83) includes a resistance component 842, an inductive component 843, a resistance component 844 and a capacitive component 845, and a cable 850 (the second power supply line of DC power supply 84) has a resistance component 852, an inductive component 853, a resistive component 854 and a capacitive component 855.

The electrostatic chuck 80, which is the load of the electrostatic chuck power source 830, has a capacitive component 81 between the electrode EL1 and the reference potential, a capacitive component 82 between the electrode EL2 and the reference potential, and a capacitive component 82 between the electrode EL1 and the electrode EL2. contains a capacitance component 85 between. The electrostatic chuck 80 also includes a current suppressing element CSE1 introduced into the first power line of the DC power supply 83 and a current suppressing element CSE2 introduced into the second power line of the DC power supply 84 .

Here, in a situation where a rapid charge transfer occurs between the capacitive component 845 of the first power supply line and the capacitive component 85 and the capacitive component 81 of the electrostatic chuck 80, the current suppressing element CSE1 It has a function to suppress it. In addition, in a situation where a rapid charge transfer occurs between the capacitive component 855 of the second power supply line and the capacitive component 85 and capacitive component 82 of the electrostatic chuck 80, the current suppressing element CSE2 has the function of suppressing

Moreover, discharge may occur unintentionally on the surface of the electrostatic chuck 80 as well. Even in that case, it is possible to suppress only the movement of charges due to discharge from the capacitive component 81 or the capacitive component 82 . That is, movement of charges from capacitive component 845 or capacitive component 855 is suppressed by current suppressing element CSE1 or current suppressing element CSE2.

As shown in FIG. 9, the electrostatic chuck 80 has therein an electrostatic chucking electrode EL1, an electrostatic chucking electrode EL2, a current suppressing element CSE1, and a current suppressing element CSE2. The current suppressing element CSE1 is provided between the electrode EL1 and the high voltage vacuum cable of the cable 840 and is electrically connected to the electrode EL1 and the high voltage vacuum cable of the cable 840 . Further, the current suppressing element CSE2 is provided between the electrode EL2 and the high voltage vacuum cable of the cable 850, and is electrically connected to the electrode EL2 and the high voltage vacuum cable of the cable 850. That is, electrode EL1 and current suppressing element CSE1 are electrically connected to retarding voltage 31 via cable 840, and electrode EL2 and current suppressing element CSE2 are electrically connected to retarding voltage 31 via cable 850. It is

As described above, since the electrodes of the electrostatic chuck 80 are provided with the current suppressing element CSE1 and the current suppressing element CSE2, the stray capacitance can be separated, and rapid movement of charges including discharge can be minimized. can be suppressed to Therefore, the reliability of the charged particle beam device 1 can be improved.

Although the invention of the present application has been specifically described above based on the embodiments, the invention of the present application is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention.

1 Charged particle beam device 10 Sample 20 Sample table 30 Retarding power supply 31 Retarding voltage 32 Output capacity 33 Output current suppression element 40 High voltage cable for vacuum 41 High voltage cable for atmosphere 42 Resistance component of cable 43 Inductive component of cable 44 Cable resistance component 45 cable capacitive component 46 connector 50 holder 51 holder capacitive component 60 stage 80 electrostatic chuck 81 capacitive component 82 capacitive component 83 DC power supply 84 DC power supply 101 control unit 110 electron source (charged particle source)
111 Conversion electrode 112 Detector 113 Scanning deflector 114 Electron lens 161 Holder transport robot 171 Sample chamber 172 Preparation chamber 173 Entrance 174 Entrance 203 Sample transport robot 210 Loading and unloading operation 301 Contact part 710 Operation 832 Output capacity 833 Output Current suppression element 840 Cable 842 Cable resistance component 843 Cable induction component 844 Cable resistance component 845 Cable capacitance component 850 Cable 852 Cable resistance component 853 Cable induction component 854 Cable resistance component 855 Cable capacitance component 862 Output capacitance 863 output current suppressing elements CSE, CSE1 to CSE3 current suppressing element CR contact region EB1 electron beam (charged particle beam)
EB2 secondary electron EL, EL1, EL2 electrode

Claims (13)

a charged particle source;
a stage provided inside the sample chamber and having a first electrode;
a holder provided on the stage and capable of holding a sample;
a first power supply provided outside the sample chamber and capable of supplying a negative voltage;
a first cable provided inside the sample chamber and electrically connected to the first power supply and the first electrode;
has
The holder is provided with a first current suppressing element electrically connected to the first electrode,
the first current suppressing element is a resistive element or a high resistance cable,
A charged particle beam device, wherein a first sheet resistance of a first conductive material included in the first current suppressing element is greater than a third sheet resistance of a third conductive material included in the first cable. a charged particle source;
a stage provided inside the sample chamber and having a first electrode;
a holder provided on the stage and capable of holding a sample;
a first power supply provided outside the sample chamber and capable of supplying a negative voltage;
a first cable provided inside the sample chamber and electrically connected to the first power supply and the first electrode;
has
The holder is provided with a first current suppressing element electrically connected to the first electrode,
The charged particle beam device, wherein the first current suppression element is an inductor or a thyristor. a charged particle source;
a stage provided inside the sample chamber and having a first electrode;
a holder provided on the stage and capable of holding a sample;
a first power supply provided outside the sample chamber and capable of supplying a negative voltage;
a first cable provided inside the sample chamber and electrically connected to the first power supply and the first electrode;
has
The holder is provided with a first current suppressing element electrically connected to the first electrode,
The holder is further provided with a second current suppressing element,
A charged particle beam device, wherein electrical characteristics of the first current suppressing element are different from electrical characteristics of the second current suppressing element. In the charged particle beam device according to claim 3 ,
each of the first current suppressing element and the second current suppressing element is a resistance element or a high resistance cable;
The first sheet resistance of the first conductive material included in the first current suppressing element and the second sheet resistance of the second conductive material included in the second current suppressing element are the third sheet resistance included in the first cable. greater than the third sheet resistance of the conductive material;
The charged particle beam device, wherein the first sheet resistance is different from the second sheet resistance. In the charged particle beam device according to claim 3 ,
the first current suppressing element and the second current suppressing element are inductors,
The charged particle beam device, wherein the number of turns of the coil in the first current suppressing element or the conductive material forming the coil is different from the number of turns of the coil in the second current suppressing element or the conductive material forming the coil. In the charged particle beam device according to claim 3 ,
each of the first current suppressing element and the second current suppressing element is a thyristor composed of a semiconductor element including a p-type semiconductor layer and an n-type semiconductor layer;
The impurity concentration of the p-type semiconductor layer, the impurity concentration of the n-type semiconductor layer, the width of the p-type semiconductor layer, or the width of the n-type semiconductor layer in the first current suppressing element are the same as those in the second current suppressing element. A charged particle beam device, wherein the impurity concentration of the p-type semiconductor layer, the impurity concentration of the n-type semiconductor layer, the width of the p-type semiconductor layer, or the width of the n-type semiconductor layer are different. a charged particle source;
a stage provided inside the sample chamber and having a first electrode;
a holder provided on the stage and capable of holding a sample;
a first power supply provided outside the sample chamber and capable of supplying a negative voltage;
a first cable provided inside the sample chamber and electrically connected to the first power supply and the first electrode;
has
The holder is provided with a first current suppressing element electrically connected to the first electrode,
A part of the stage constitutes a transport path for transporting the holder,
The first electrode is provided on the transport path,
When the holder is transported through the transport path, at least during a period from when the holder is installed on the transport path to when the holder is fixed to the stage, the first electrode has the first A charged particle beam device to which the negative voltage is applied from a power supply. In the charged particle beam device according to claim 7 ,
The charged particle beam device, wherein the first current suppressing element is in contact with the first electrode when the holder is fixed to the stage. In the charged particle beam device according to claim 8 ,
When the sample is analyzed inside the sample chamber while the holder is fixed to the stage, the sample is irradiated with a charged particle beam emitted from the charged particle source. The charged particle beam device, wherein the negative voltage is applied from the first power source to the holder during the period through the first cable, the first electrode and the first current suppressing element. a charged particle source;
an electrostatic chuck provided inside the sample chamber, having a first electrode, and capable of holding a sample;
a first power supply provided outside the sample chamber and capable of supplying a negative voltage;
a first cable provided inside the sample chamber and electrically connected to the first power supply and the first electrode;
has
the electrostatic chuck further comprising a first current suppressing element provided between the first electrode and the first cable and electrically connected to the first electrode and the first cable;
the first current suppressing element is a resistive element or a high resistance cable,
A charged particle beam device, wherein a first sheet resistance of a first conductive material included in the first current suppressing element is greater than a third sheet resistance of a third conductive material included in the first cable. a charged particle source;
an electrostatic chuck provided inside the sample chamber, having a first electrode, and capable of holding a sample;
a first power supply provided outside the sample chamber and capable of supplying a negative voltage;
a first cable provided inside the sample chamber and electrically connected to the first power supply and the first electrode;
has
the electrostatic chuck further comprising a first current suppressing element provided between the first electrode and the first cable and electrically connected to the first electrode and the first cable;
The charged particle beam device, wherein the first current suppression element is an inductor or a thyristor. A holder for holding a sample to be analyzed by a charged particle beam device,
a contact area for contacting electrodes of a stage provided inside the charged particle beam device;
a current limiting element provided in the contact area and constituted by an inductor or a thyristor;
A holder. 13. A holder according to claim 12 , wherein
The holder, wherein the contact area is provided with a plurality of the current suppressing elements each having different electrical properties.

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