Charged particle beam device and method for producing sample

Abstract

This charged particle beam device (100) comprises: an electron beam lens barrel (2); a focused ion beam lens barrel (3); a detector (6); a control unit (C0) having an image forming unit (C8); a sample stage (20); and a holder unit (60). The holder unit (60) has: a sample holder (50) capable of holding a sample (Q); and a base (40) including a tilt drive mechanism (41) for tilting the sample holder (50). The sample stage (20) has a sample stage drive mechanism (21), a terminal (24) connected to a wiring (28) for supplying a drive current to the tilt drive mechanism (41), and a terminal (25) for electrically connecting to the sample holder (50). The sample holder (50) is electrically insulated from the base (40).

Description

Charged particle beam device and sample preparation method

[0001] The present invention relates to a charged particle beam device and a sample preparation method, and more particularly to a charged particle beam device equipped with a holder unit having a two-axis tilt drive mechanism capable of tilting a sample holder, and a sample preparation method using the charged particle beam device.

[0002] Various charged particle beam devices are used in the defect analysis of semiconductor devices. For example, a scanning electron microscope (SEM) or a transmission electron microscope (TEM) is used as a charged particle beam device to observe and capture images of defective areas. Furthermore, an FIB-SEM device capable of irradiating a focused ion beam (FIB) is used as a charged particle beam device to prepare samples for observation.

[0003] The sample stages of recent charged particle beam instruments have five-axis (X-axis, Y-axis, Z-axis, T-axis, and R-axis) drive mechanisms. However, because the tilt angle or orientation of the sample cannot be changed, problems arise, such as the formation of irregularities on the processed surface of the sample, known as the curtaining effect, and the increased workload. In particular, recent semiconductor devices have developed microstructures, such as FIN-FET structures, that are three-dimensionally complex. This makes it even more difficult to suppress the curtaining effect.

[0004] Therefore, as disclosed in Patent Document 1, for example, a charged particle beam device has been developed that has a holder unit (double tilt holder) mounted on the sample stage and that has a tilt drive mechanism for two axes (S-axis and F-axis). When irradiating an ion beam onto a sample and processing the sample, the irradiation angle of the ion beam can be changed by tilting the holder unit. This makes it possible to suppress the curtaining effect.

[0005] JP 2016-72089 A

[0006] When processing a sample with an ion beam, if it is possible to accurately acquire not only an SEM image of the sample but also a current image of the sample, various effects can be obtained. For example, if an EBIC (Electron Beam Induced Current) image is acquired as a current image of the sample during ion beam processing and is superimposed on the SEM image of the sample, it is possible to change the contrast only in desired areas, which can dramatically increase the success rate of automated processing, including image matching.

[0007] The holder unit includes a sample holder for holding a sample, a base on which the sample holder is mounted, and a tilt drive mechanism attached to the base. To tilt the sample holder, the tilt drive mechanism must be connected to wiring for supplying a drive current. Therefore, in existing holder units, the drive current is supplied not only to the base but also to the sample holder, making it difficult to accurately obtain a current image of the sample.

[0008] One of the objects of the present application is to provide a charged particle beam apparatus that can acquire not only an SEM image of a sample but also a current image of the sample when processing the sample with an ion beam.

[0009] Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

[0010] A brief summary of a representative embodiment of the present invention will be given below.

[0011] A charged particle beam device according to one embodiment includes an electron beam column capable of irradiating an electron beam, an ion beam column capable of irradiating an ion beam at a position irradiated with the electron beam, a detector capable of detecting secondary electrons or backscattered electrons emitted from the sample as a signal when the sample is irradiated with the electron beam, a controller having an image forming unit, a sample stage, and a holder unit detachable from the sample stage. The holder unit includes a sample holder capable of holding the sample, and a base including a tilt drive mechanism for tilting the sample holder and on which the sample holder is mounted. The sample stage has a sample stage drive mechanism for controlling the attitude of the sample stage, a first terminal connected to wiring for supplying drive current to the tilt drive mechanism, and a second terminal for electrically connecting to the sample holder. The controller is electrically connected to the electron beam column, the ion beam column, the detector, the sample stage drive mechanism, the first terminal, and the second terminal. The control unit controls the electron beam column, the ion beam column, the detector, the sample stage drive mechanism, the tilt drive mechanism, and the image formation unit. The sample holder is electrically insulated from the base. When the holder unit is attached to the sample stage, the tilt drive mechanism is electrically connected to the first terminal, and the sample holder is electrically connected to the second terminal.

[0012] According to one embodiment, when processing a sample with an ion beam, not only an SEM image of the sample but also a current image of the sample can be acquired.

[0013] 1 is a schematic diagram showing a charged particle beam device according to the first to fifth embodiments; FIG. 2 is a cross-sectional view showing details of a sample stage and a holder unit according to the first to fifth embodiments; FIG. 3 is a schematic diagram showing a tilting operation of a holder unit according to the first to fifth embodiments; FIG. 4 is a front view showing an enlarged portion of a sample holder according to the first to fifth embodiments; FIG. 5 is a side view showing an enlarged portion of a sample holder according to the first to fifth embodiments; FIG. 6 is a perspective view showing an example of a sample according to the first to fifth embodiments; FIG. 7 is a flowchart showing a sample preparation method according to the first, second, third and fifth embodiments; FIG. 8 is a schematic diagram corresponding to the flowchart of FIG. 7; FIG. 9 is a schematic diagram showing a sample preparation method according to the fourth embodiment; FIG. 10 is a schematic diagram showing a sample preparation method according to the fourth embodiment; FIG. 11 is a schematic diagram showing a sample preparation method according to the first to fifth embodiments; FIG. 12 is a schematic diagram showing a sample preparation method according to the second embodiment;

[0014] Hereinafter, embodiments will be described in detail with reference to the drawings. In all drawings for explaining the embodiments, components having the same functions are designated by the same reference numerals, and repeated explanations thereof will be omitted. In the following embodiments, explanations of the same or similar parts will not be repeated unless particularly necessary.

[0015] The X, Y, and Z directions described herein intersect and are perpendicular to one another. In the description herein, the Z direction is the vertical or height direction of a structure.

[0016] (Embodiment 1) <Structure of Charged Particle Beam Apparatus> Fig. 1 is a schematic diagram showing a charged particle beam apparatus 100 in embodiment 1. The charged particle beam apparatus 100 is a composite charged particle beam apparatus equipped with multiple beam column tubes, such as an electron beam column tube and an ion beam column tube.

[0017] 1 , the charged particle beam instrument 100 includes a sample chamber 1, an electron beam column 2, a focused ion beam column 3, a gas ion beam column 4, a sample stage 20, a holder unit 60, a needle 5, a detector 6, a gas supplier 7, an integrated controller C0, an electron beam controller C1, a focused ion beam controller C2, a gas ion beam controller C3, a sample stage controller C4, a needle controller C5, a detector controller C6, a gas supply controller C7, and an image forming unit C8. In addition, a display unit 8 and an operation unit 9 electrically connected to the integrated controller C0 are provided inside or outside the charged particle beam instrument 100.

[0018] An electron beam column 2 capable of irradiating an electron beam 2a is attached to the sample chamber 1. The electron beam column 2 includes all of the components necessary for an SEM device, such as an electron source for generating the electron beam 2a, a lens for focusing the electron beam 2a, and a deflection system for scanning and shifting the electron beam 2a.

[0019] The electron beam controller C1 is electrically connected to the electron beam column 2 and controls the operation of the electron beam column 2. For example, the generation of the electron beam 2a from the electron source and the driving of the deflection system are controlled by the electron beam controller C1.

[0020] A focused ion beam column 3 capable of irradiating an ion beam (focused ion beam) 3a is attached to the sample chamber 1. The focused ion beam column 3 includes all of the components necessary for an FIB device, such as a liquid metal ion source for generating the ion beam 3a, a lens for focusing the ion beam 3a, and a deflection system for scanning and shifting the ion beam 3a.

[0021] The focused ion beam controller C2 is electrically connected to the focused ion beam column 3 and controls the operation of the focused ion beam column 3. For example, the irradiation of the ion beam 3a from the liquid metal ion source and the driving of the deflection system are controlled by the focused ion beam controller C2.

[0022] A gas ion beam column 4 capable of irradiating an ion beam (gas ion beam) 4a is attached to the sample chamber 1. The gas ion beam column 4 includes all of the components necessary for a GIB (Gas Ion Beam) device, such as a gas ion source for generating the ion beam 4a, a lens for focusing the ion beam 4a, and a deflection system for scanning and shifting the ion beam 4a. The gas ion source uses helium, argon, xenon, oxygen, or the like as an ion source gas.

[0023] The gas ion beam control unit C3 is electrically connected to the gas ion beam column 4 and controls the operation of the gas ion beam column 4. For example, the irradiation of the ion beam 4a from the gas ion source and the driving of the deflection system are controlled by the gas ion beam control unit C3.

[0024] During processing of the sample Q by the ion beam 3a from the focused ion beam column 3, a damaged layer may be formed in the sample Q. The gas ion beam column 4 is mainly used to remove such a damaged layer. The ion beam 3a and the ion beam 4a can be irradiated onto the irradiation position of the electron beam 2a.

[0025] A sample stage 20 is provided in the sample chamber 1. The sample stage 20 can be equipped with a holder unit 60 that holds a sample Q. The sample stage 20 has a sample stage drive mechanism 21 for controlling the attitude of the sample stage 20. The sample stage drive mechanism 21 includes a five-axis drive mechanism consisting of a movement mechanism (X-axis, Y-axis, Z-axis), a tilt mechanism (T-axis), and a rotation mechanism (R-axis). The sample stage control unit C4 is electrically connected to the sample stage drive mechanism 21 and controls the operation of the sample stage drive mechanism 21.

[0026] The holder unit 60 attached to the sample stage 20 can be moved in the X, Y and Z directions by the movement mechanism of the sample stage drive mechanism 21, can be tilted around the X or Y direction as the central axis by the tilt mechanism of the sample stage 20, and can be rotated around the Z direction as the central axis by the rotation mechanism of the sample stage 20.

[0027] The holder unit 60 is detachably attached to the sample stage 20 and has a base 40 and a sample holder 50. The sample Q is held in the sample holder 50. Details of the sample stage 20, the base 40, and the sample holder 50 will be described later in detail with reference to FIG.

[0028] A needle 5 is provided in the sample chamber 1 to attach and detach the sample Q to and from the sample holder 50. A needle control unit C5 is electrically connected to the needle 5 and controls the operation of the needle 5. A current measurement unit EC4 is also electrically connected to the needle 5 and the integrated control unit C0. When the needle 5 is irradiated with the electron beam 2a, the current measurement unit EC4 measures the current flowing from the needle 5 as a current signal.

[0029] A detector 6 is provided in the sample chamber 1. The detector 6 is capable of detecting secondary electrons or backscattered electrons emitted from the sample Q as a signal 2b when the sample Q is irradiated with an electron beam 2a. A detector control unit C6 is electrically connected to the detector 6 and controls the operation of the detector 6.

[0030] A gas supplier 7 is provided in the sample chamber 1. A gas supply controller C7 is connected to the gas supplier 7 and controls the type and amount of gas supplied into the sample chamber 1.

[0031] By supplying a deposition gas from the gas supplier 7 to the sample Q simultaneously with the irradiation of the ion beam 3a, solid components decomposed from the deposition gas can be deposited on the surface of the sample Q. Furthermore, by supplying an etching gas from the gas supplier 7 to the sample Q simultaneously with the irradiation of the ion beam 3a, etching can be selectively promoted.

[0032] The sample Q can be connected to the sample holder 50 and the needle 5 by deposition, and the sample Q can be separated from the sample holder 50 and the needle 5 by etching.

[0033] The operation unit 9 is a device, such as a keyboard or a mouse, for the user to input various instructions. Such various instructions include inputting information about the sample Q, changing the irradiation conditions of the electron beam 2a, the ion beam 3a, and the ion beam 4a, and changing the positions of the sample stage 20 and the needle 5. The display unit 8 displays a GUI screen and the like. On the GUI screen, the user can confirm the input of various instructions via the operation unit 9 and can also confirm the captured image and the like.

[0034] The image forming unit C8 is included in the integrated control unit C0. The image forming unit C8 has an arithmetic processing circuit that processes the signal 2b detected by the detector 6 and creates an image. Therefore, the image forming unit C8 can generate an SEM image of the sample Q from the signal 2b. The image forming unit C8 can also form an absorbed current image of the needle 5 from the scanning signal of the electron beam 2a and the current signal of the current measuring unit EC4.

[0035] The integrated control unit C0 is a computer system including various semiconductor devices such as a CPU. The integrated control unit C0 is electrically connected to each of the electron beam control unit C1, focused ion beam control unit C2, gas ion beam control unit C3, sample stage control unit C4, needle control unit C5, detector control unit C6, gas supply control unit C7, and image formation unit C8, and controls these units in an integrated manner. Therefore, the control performed by each unit C1 to C8 can also be said to be performed by the integrated control unit C0, and the integrated control unit C0 may sometimes be simply referred to as a "control unit."

[0036] <Configuration of Holder Unit> The configuration and tilting operation of the holder unit 60 will be described below with reference to FIGS.

[0037] 2, the holder unit 60 has a sample holder 50 capable of holding a sample Q, and a base 40 on which the sample holder 50 can be mounted. The base 40 includes a tilt drive mechanism (motor) 41 for tilting the sample holder 50. Although not shown, the base 40 is provided with a shaft connected to the sample holder 50. The tilt drive mechanism 41 rotates the shaft, causing the sample holder 50 to tilt. The sample holder 50 is electrically insulated from the base 40.

[0038] As shown in FIG. 3 , the tilt drive mechanism 41 can tilt the sample holder 50 around two mutually orthogonal tilt axes, the F-axis (flip axis) and the S-axis (swing axis). In FIG. 3 , the sample holder 50 tilts in a rotation direction FR1 around the F-axis as the central axis, and tilts in a rotation direction SR1 around the S-axis as the central axis. For example, when irradiating an ion beam 3 a onto an observation surface of a sample Q to process the observation surface, the incident angle of the ion beam 3 a can be adjusted by tilting the sample holder 50 around the S-axis as the central axis. This can suppress the curtaining effect.

[0039] As shown in Fig. 2, the sample holder 50 has a TEM grid 51. As shown in Figs. 4 and 5, the TEM grid 51 is provided with a plurality of pillars 52. The sample Q is connected to the pillars 52 by deposition. The TEM grid 51 tilts in a rotation direction FR2 linked to the rotation direction FR1 in Fig. 3, and tilts in a rotation direction SR2 linked to the rotation direction SR1 in Fig. 3.

[0040] The tilt drive mechanisms 41 for the two tilt axes (S-axis and F-axis) are controlled independently of each other and also independently of the drive mechanisms for the five axes (X-axis, Y-axis, Z-axis, T-axis, and R-axis) of the sample stage 20. The eucentric position of the tilt mechanism (T-axis) of the sample stage 20 coincides with the eucentric position of the F-axis and S-axis. The eucentric position corresponds to the irradiation positions of the electron beam 2a, ion beam 3a, and ion beam 4a on the sample Q. With this configuration, even if the sample stage 20 and the TEM grid 51 are tilted simultaneously, the irradiation target will not shift from its original irradiation position, enabling accurate processing and observation.

[0041] <Configuration of Sample Stage> The configuration of the sample stage 20 will be described below with reference to FIG.

[0042] As shown in FIG. 2, the sample stage 20 has a top plate 22 , a wiring board 23 , a tilt drive terminal 24 , a current acquisition terminal 25 , a slip ring mechanism 27 , and a wiring fixing portion 31 .

[0043] The charged particle beam device 100 also includes a tilt drive controller C9, a probe 26, a probe controller C10, current measuring units EC1, EC2, and EC3, and a retarding power supply Vdr. The integrated controller C0 is electrically connected to each of the tilt drive controller C9 and the probe controller C10 and controls them in an integrated manner. Therefore, it can be said that the controls performed by the tilt drive controller C9 and the probe controller C10 are performed by the integrated controller C0.

[0044] Among the components that make up the sample stage 20, the top plate 22 is a component on which the base 40 is mounted. The wiring board 23 is a wiring board on which a plurality of wirings, active elements, passive elements, etc. are provided, and includes terminals 24 on its surface. The terminals 24 are connected to wiring 28 that supplies a drive current to the tilt drive mechanism 41, and are electrically connected to the tilt drive controller C9 via a slip ring mechanism 27.

[0045] The tilt drive controller C9 is provided to control the operation of the tilt drive mechanism 41. For example, the power for driving the tilt drive mechanism 41 and tilt operation instructions from the user are transmitted from the tilt drive controller C9 to the tilt drive mechanism 41.

[0046] The terminal 25 is provided for electrical connection to the sample holder 50. The current measurement unit EC1 is electrically connected to the terminal 25 and the integrated control unit C0 by wiring 29. The terminal 25 can also be electrically connected to the ground potential and the retarding power supply Vdr. Switching from the terminal 25 to the current measurement unit EC1, the ground potential, or the retarding power supply Vdr is controlled by the integrated control unit C0. In the first embodiment, the terminal 25 is electrically connected to the current measurement unit EC1.

[0047] When the electron beam 2a is irradiated onto the sample Q, the current measurement unit EC1 measures, as a current signal, the current flowing from the sample Q via the sample holder 50 and the terminal 25. The image formation unit C8 can form an absorbed current image of the sample Q from the scanning signal of the electron beam 2a and the current signal of the current measurement unit EC1.

[0048] A probe 26 capable of coming into contact with a sample Q held in a sample holder 50 is provided near the terminal 25. A probe control unit C10 is electrically connected to the probe 26 and controls the operation of the probe 26. Current measurement units EC2 and EC3 are also electrically connected to the probe 26 and the integrated control unit C0 by wiring 30. Switching from the probe 26 to the current measurement unit EC2 or the current measurement unit EC3 is controlled by the integrated control unit C0.

[0049] When the electron beam 2a is irradiated onto the sample Q, the probe 26 comes into contact with the sample Q. When the probe 26 is electrically connected to the current measurement unit EC2, the current measurement unit EC2 measures the current flowing from the sample Q via the probe 26 as a current signal. The image formation unit C8 can form an electron beam induced current image (EBIC image) of the sample Q from the scanning signal of the electron beam 2a and the current signal of the current measurement unit EC2. In this case, the image formation unit C8 can also acquire an SEM image of the sample Q and can also form a captured image in which the electron beam induced current image and the SEM image are superimposed.

[0050] Furthermore, when the probe 26 is electrically connected to the current measurement unit EC3, the current measurement unit EC3 measures, as a current signal, the current flowing from the sample Q via the probe 26. The image formation unit C8 can form an absorbed current image (EBAC image) of the sample Q from the scanning signal of the electron beam 2a and the current signal of the current measurement unit EC3.

[0051] The holder unit 60 is detachably attached to the sample stage 20, more specifically, the top plate 22, the terminal 24, and the terminal 25. When the holder unit 60 is attached to the sample stage 20, the tilt drive mechanism 41 is electrically connected to the terminal 24 via the internal wiring of the base 40, and the sample holder 50 is electrically connected to the terminal 25.

[0052] Therefore, by attaching the holder unit 60 to the sample stage 20, the tilt drive control unit C9 can drive the tilt drive mechanism 41, the current measurement units EC1, EC2, and EC3 can measure the current signal of the sample Q, and the image formation unit C8 can acquire a current image (absorbed current image, electron beam induced current image) of the sample Q. Furthermore, since the sample holder 50 is electrically insulated from the base 40, the tilt operation of the sample holder 50 and the acquisition of a current image can be performed independently and simultaneously.

[0053] The wires 28, 29, and 30 are electrically insulated from one another. The slip ring mechanism 27 and the wire fixing portion 31 are provided inside the sample stage 20. The wire fixing portion 31 is located on the slip ring mechanism 27. The wires 28, 29, and 30 are fixed to the wire fixing portion 31 using metal fittings or the like. Here, the slip ring mechanism 27 is provided on the wire 28, but slip ring mechanisms may also be provided on the wires 29 and 30.

[0054] Since the sample stage 20 is configured in this manner, the wiring 28, wiring 29, and wiring 30 do not become tangled even when the sample stage 20 is rotated, and the wiring 28, wiring 29, and wiring 30 can be connected to the tilt drive control unit C9, probe control unit C10, current measurement units EC1, EC2, EC3, ground potential, and retarding power supply Vdr outside the sample stage 20.

[0055] According to such a charged particle beam device 100, when processing a sample Q using an ion beam 3a, not only an SEM image of the sample Q but also a current image of the sample Q (absorbed current image, electron beam induced current image) can be obtained without removing the sample Q from the sample chamber 1.

[0056] <Configuration of Sample Q> An example of the sample Q will be described below with reference to FIG.

[0057] A typical sample used in the charged particle beam device 100 is a thin sample cut out from a portion of a semiconductor wafer. The semiconductor wafer includes, for example, a semiconductor substrate, semiconductor elements such as transistors formed on the semiconductor substrate, and a plurality of wirings formed on the semiconductor elements.

[0058] Sample Q shown in Figure 6 includes a semiconductor layer PS in which p-type impurities are introduced into a semiconductor substrate, a semiconductor layer NS in which n-type impurities are introduced into a semiconductor substrate, conductor patterns CF including gate electrodes and wiring, and insulating layers IL formed between each conductor pattern CF.

[0059] <Method of Preparing Sample in First Embodiment> A method of preparing sample Q in the first embodiment will be described below with reference to Figures 7 and 8. Note that Figure 8 schematically illustrates steps S1 to S9 shown in Figure 7. In the first embodiment, steps S1 to S5 are used. Furthermore, at the time of step S1, sample Q is already held in sample holder 50. That is, sample Q is connected to columnar portion 52.

[0060] In the first embodiment, the sample Q is prepared in a state where the terminal 25 is electrically connected to the current measuring unit EC1 and the probe 26 is not in contact with the sample Q.

[0061] First, in step S1, cross-section processing is performed using an ion beam 3a. For example, the sample Q is tilted in a rotation direction FR2 around the F axis as the central axis, and the observation surface of the sample Q is irradiated with the ion beam 3a to process the observation surface.

[0062] Next, in step S2, cross-section finishing is performed to suppress the curtaining effect. The specimen Q is tilted in a rotation direction SR2 around the S axis as the central axis, and the observation surface is irradiated with the ion beam 3a or 4a to process the observation surface. By changing the tilt angle of the specimen Q and changing the irradiation angle of the ion beam 3a or 4a, the observation surface is irradiated with the ion beam 3a or 4a from multiple directions.

[0063] Next, in step S3, an SEM image of the cross section is acquired. The sample Q is tilted in the rotation direction FR2 around the F axis, and the electron beam 2a is irradiated onto the observation surface of the sample Q to acquire an SEM image of the observation surface. At this time, step S4 is also performed at the same time, and an absorbed current image of the sample Q is also acquired.

[0064] Next, in step S5, steps S1 to S4 are repeated until the observation surface becomes the desired cross section. When the desired cross section is exposed, a change occurs in the current from the specimen holder 50, and the desired current is obtained. This change is regarded as the end point of cross section processing. In other words, processing of the observation surface can be terminated based on the change in the current signal from the current measurement unit EC1.

[0065] (Embodiment 2) A charged particle beam device 100 according to embodiment 2 will be described below. In the following description, differences from embodiment 1 will be mainly described, and descriptions of points that overlap with embodiment 1 will be omitted.

[0066] In the second embodiment, when processing the sample Q with the ion beam 3a, the terminal 25 and the probe 26 are used to acquire an electron beam induced current image (EBIC image) of the sample Q. When irradiating the sample Q with the electron beam 2a, the probe 26 is brought into contact with the sample Q, and the terminal 25 is connected to the ground potential. In the case of the sample Q shown in FIG. 6 , the portion that is brought into contact with the probe 26 and the portion that is irradiated with the electron beam 2a are, for example, the p-type semiconductor layer PS or the n-type semiconductor layer NS.

[0067] When the electron beam 2a is irradiated onto the sample Q, hole-electron pairs are generated inside the sample Q. Hole-electron pairs normally recombine and disappear, but when hole-electron pairs are generated in a region with an internal electric field, such as a depletion layer, the carriers drift due to the internal electric field, generating an electromotive current. The current measurement unit EC2 measures the current flowing from the sample Q via the probe 26 as a current signal. The image formation unit C8 can form an EBIC image of the sample Q from the scanning signal of the electron beam 2a and the current signal of the current measurement unit EC2. In addition, by acquiring both the EBIC image and the SEM image and forming a captured image by superimposing them, the user can confirm the position of the PN junction and the extent of the depletion layer on the display unit 8.

[0068] <Method of Preparing Sample in Second Embodiment> The method of preparing sample Q in the second embodiment is substantially the same as the method of preparing sample Q in the first embodiment from steps S1 to S4.

[0069] The observation surface of the sample Q is irradiated with the electron beam 2a, an SEM image of the observation surface is acquired (step S3), and an EBIC image of the observation surface is acquired (step S4). Thereafter, a photographed image is acquired in which the SEM image and the EBIC image are superimposed.

[0070] Next, in step S5, steps S1 to S4 are repeated until the observation surface becomes the desired cross section. When the desired cross section is exposed, a change occurs in the current from the probe 26, and the desired current is obtained. This change is considered to be the end point of cross section processing. In other words, processing of the observation surface can be terminated based on the change in the current signal from the current measurement unit EC2.

[0071] (Embodiment 3) A charged particle beam device 100 according to embodiment 3 will be described below. In the following description, differences from embodiment 1 will be mainly described, and descriptions of points that overlap with embodiment 1 will be omitted.

[0072] In the third embodiment, when processing the sample Q with the ion beam 3a, a terminal 25 and a probe 26 are used to acquire an absorbed current image (EBAC image) of the sample Q. When irradiating the sample Q with the electron beam 2a, the probe 26 is brought into contact with the sample Q, and the terminal 25 is connected to the ground potential. In the case of the sample Q shown in FIG. 6 , the portion that is brought into contact with the probe 26 and the portion that is irradiated with the electron beam 2a are, for example, wiring of the conductor pattern CF formed on the surface of the sample Q.

[0073] When the electron beam 2a is irradiated onto the sample Q, the current measurement unit EC3 measures, as a current signal, the current flowing from the sample Q via the probe 26. The image formation unit C8 can form an EBAC image of the sample Q from the scanning signal of the electron beam 2a and the current signal of the current measurement unit EC3.

[0074] <Method of Preparing Sample in Third Embodiment> The method of preparing sample Q in the third embodiment is the same as the method of preparing sample Q in the first embodiment from step S1 to step S2.

[0075] After step S2, step S6 is performed. In step S6, the sample Q is tilted in a rotation direction FR2 around the F axis as the central axis, and an electron beam 2a is irradiated onto the wiring formed on the surface of the sample Q to obtain an SEM image of the surface. At this time, step S7 is also performed at the same time to obtain a second absorbed current image of the conductor pattern CF connected to the wiring.

[0076] Next, in step S8, steps S1, S2, S6, and S7 are repeated until the observation surface becomes the desired cross section. When the desired cross section is exposed, a change occurs in the current from the probe 26, and the desired current is obtained. This change is considered to be the end point of cross section processing. In other words, processing of the observation surface can be terminated based on the change in the current signal from the current measurement unit EC3.

[0077] Next, in step S9, an SEM image of the cross section is acquired by tilting the sample Q in a rotation direction FR2 around the F axis as the central axis, irradiating the observation surface of the sample Q with the electron beam 2a, and acquiring an SEM image of the observation surface.

[0078] 9 to 14, a method for fabricating a sample Q in accordance with the fourth embodiment will be described below. In the following description, differences from the first to third embodiments will be mainly described, and explanations of points that overlap with the first to third embodiments will be omitted.

[0079] In the fourth embodiment, automatic micro-sampling of the sample Q is performed using the needle 5. Figures 9 to 11 show how the sample Q is connected to the columnar portion 52 of the sample holder 50.

[0080] 9, the sample Q connected to the needle 5 is brought close to the columnar portion 52. The sample Q is connected to the needle 5 by a deposition film DM1.

[0081] 10, the sample Q connected to the needle 5 is connected to the columnar portion 52 by deposition. That is, an ion beam 3a is irradiated near the tip of the sample Q, and a deposition gas is supplied from a gas supplier 7. Solid components decomposed from the deposition gas are deposited as a deposition film DM2. This deposition film DM2 connects the sample Q to the columnar portion 52.

[0082] 11, an ion beam 3a is irradiated onto the connection point between the needle 5 and the sample Q, and the needle 5 is separated from the sample Q. That is, by irradiating the deposition film DM1 with the ion beam 3a and supplying an etching gas from the gas supplier 7, etching of the deposition film DM1 is selectively promoted. After removing the deposition film DM1, the needle 5 is moved away from the sample Q. Note that when removing the deposition film DM1, a portion of the sample Q may also be cut.

[0083] 9 to 11 are performed while irradiating the needle 5 with the electron beam 2a and acquiring an absorption current image of the needle 5. When the sample Q is connected to the columnar portion 52 and when the needle 5 is detached from the sample Q, the absorption current flowing through the needle 5 changes. Using this change, the connection state between the sample Q and the columnar portion 52 and the connection state between the sample Q and the needle 5 can be determined.

[0084] 10, it can be determined based on the change in the current signal of the current measuring unit EC4 that the sample Q is connected to the columnar portion 52. In Fig. 11, it can be determined based on the change in the current signal of the current measuring unit EC4 that the needle 5 is detached from the sample Q.

[0085] 9 to 11, when the needle 5 is irradiated with the electron beam 2a and an absorbed current image of the needle 5 is acquired, the terminal 25 is connected to the ground potential. By fixing the sample holder 50 and the sample Q to the ground potential, the sample Q is less susceptible to the influence of various radio waves around it, and noise is less likely to be introduced into the absorbed current image. In other words, it is possible to acquire a more accurate absorbed current (electrical signal).

[0086] 9 to 11, steps S1 to S9 shown in Fig. 7 and Fig. 8 are performed. After that, the sample Q may be transferred to another holder, as will be described below with reference to Fig. 13 and Fig. 14. Here, an example will be described in which the sample Q is processed into a sample to be used in atom probe measurement (atom probe sample), and then the sample Q is transferred to another holder.

[0087] 12 shows how the sample Q is processed into an atom probe sample. As shown in FIG. 12, with the sample Q connected to the columnar portion 52, the sample Q is tilted in a rotation direction FR2 around the F axis as the central axis, for example, and the sample Q is irradiated with an ion beam 3a, thereby processing the sample Q into a conical shape. By changing the tilt angle of the sample Q and the irradiation angle of the ion beam 3a, the sample Q is irradiated with the ion beam 3a from multiple directions.

[0088] 13, the sample Q is connected to the needle 5 by deposition. That is, with the needle 5 brought close to the sample Q, an ion beam 3a is irradiated near the tip of the needle 5, and a deposition gas is supplied from the gas supplier 7. Solid components decomposed from the deposition gas are deposited as a deposition film DM3. This deposition film DM3 connects the sample Q and the needle 5.

[0089] 14, an ion beam 3a is irradiated onto the connection point between the columnar portion 52 and the sample Q, and the sample Q connected to the needle 5 is separated from the columnar portion 52. That is, by irradiating the deposition film DM2 with the ion beam 3a and supplying an etching gas from the gas supplier 7, etching of the deposition film DM2 is selectively promoted. After removing the deposition film DM2, the needle 5 and the sample Q are moved away from the columnar portion 52, and the sample Q is transferred to another holder.

[0090] 13 and 14 are performed while irradiating the needle 5 with the electron beam 2a and acquiring an absorption current image of the needle 5. When the sample Q is connected to the needle 5 and when the sample Q is detached from the columnar portion 52, the absorption current flowing through the needle 5 changes. Using this change, the connection state between the sample Q and the needle 5 and the connection state between the sample Q and the columnar portion 52 can be determined.

[0091] 13, it can be determined that the sample Q has been connected to the needle based on a change in the current signal from the current measuring unit EC4. In FIG. 14, it can be determined that the sample Q has been detached from the columnar portion 52 based on a change in the current signal from the current measuring unit EC4.

[0092] 9 to 11, in the steps of Figures 13 and 14, when the needle 5 is irradiated with the electron beam 2a and an absorbed current image of the needle 5 is acquired, the terminal 25 is connected to the ground potential, which makes it difficult for noise to enter the absorbed current image.

[0093] The automatic micro-sampling of the fourth embodiment described above can be applied in combination with any of the methods for producing the sample Q of the first to third embodiments.

[0094] Fifth Embodiment A charged particle beam device 100 according to a fifth embodiment will be described below. In the following description, differences from the first embodiment will be mainly described, and descriptions of points that overlap with the first embodiment will be omitted.

[0095] In the fifth embodiment, when an SEM image is acquired, a retarding potential is supplied to the sample holder 50 and the sample Q. That is, when the electron beam 2 a is irradiated onto the sample Q, the terminal 25 is electrically connected to the retarding power supply Vdr, and the retarding potential is supplied to the terminal 25 from the retarding power supply Vdr.

[0096] In the fifth embodiment, since the terminal 25 is connected to the retarding power supply Vdr, it is not possible to acquire a current image along with the SEM image as in the first to third embodiments. However, it is possible to reduce damage to the sample Q caused by the energy of the electron beam 2a, and it is possible to acquire an SEM image with higher resolution than in the case where there is no retarding effect.

[0097] <Method of Preparing Sample in Fifth Embodiment> The method of preparing sample Q in the fifth embodiment is almost the same as the method of preparing sample Q in the first embodiment, except that step S4 is not performed.

[0098] In step S3, the surface to be observed is irradiated with the electron beam 2a and an SEM image of the surface to be observed is obtained while a retarding potential is being supplied to the sample Q via the terminal 25. In step S5, steps S1 to S3 are repeated until the surface to be observed has the desired cross section. The end point of cross section processing is when it is confirmed in the SEM image that the desired cross section has been exposed.

[0099] The present invention has been specifically described above based on the above embodiment, but the present invention is not limited to the above embodiment and can be modified in various ways without departing from the spirit of the present invention.

[0100] 100 Charged particle beam device 1 Sample chamber 2 Electron beam column 2a Electron beam 2b Signal (secondary electrons, backscattered electrons) 3 Ion beam column (focused ion beam column) 3a Ion beam (focused ion beam) 4 Ion beam column (gas ion beam column) 4a Ion beam (gas ion beam) 5 Needle 6 Detector 7 Gas supplier 8 Display unit 9 Operation unit 20 Sample stage 21 Sample stage drive mechanism 22 Top plate 23 Wiring board 24 Terminal for tilt drive 25 Terminal for current acquisition 26 Probe 27 Slip ring mechanism 28, 29, 30 Wiring 31 Wiring fixing unit 40 Base 41 Tilt drive mechanism (motor) 50 Sample holder 51 TEM grid 52 Columnar portion 60 Holder unit C0 Integrated control unit (control unit) C1 Electron beam control unit C2 Focused ion beam control unit C3 Gaseous ion beam control unit C4 Sample stage control unit C5 Needle control unit C6 Detector control unit C7 Gas supply control unit C8 Image formation unit C9 Tilt drive control unit C10 Probe control unit CF Conductive pattern DM1, DM2, DM3 Deposition film EC1, EC2, EC3, EC4 Current measurement unit FR1, FR2 Rotation direction IL Insulation layer NS n-type semiconductor layer PS p-type semiconductor layer Q Sample SR1, SR2 Rotation direction Vdr Retarding power supply

Claims

1. An electron beam column capable of irradiating an electron beam; an ion beam column capable of irradiating an ion beam at a position irradiated with the electron beam; a detector capable of detecting, as a signal, secondary electrons or reflected electrons emitted from a sample when the sample is irradiated with the electron beam; a control unit having an image forming unit; a sample stage; and a holder unit detachable from the sample stage, wherein the holder unit has: a sample holder capable of holding the sample; and a base including a tilt drive mechanism for tilting the sample holder and on which the sample holder is mounted, wherein the sample stage has: a sample stage drive mechanism for controlling the attitude of the sample stage; a first terminal connected to wiring for supplying a drive current to the tilt drive mechanism; and a second terminal for electrically connecting to the sample holder, and the control unit is electrically connected to the electron beam column, the ion beam column, the detector, the sample stage drive mechanism, the first terminal, and the second terminal, A charged particle beam device, wherein the control unit controls the electron beam column, the ion beam column, the detector, the sample stage drive mechanism, the tilt drive mechanism and the image forming unit, the sample holder is electrically insulated from the base, and when the holder unit is attached to the sample stage, the tilt drive mechanism is electrically connected to the first terminal and the sample holder is electrically connected to the second terminal.

2. A charged particle beam device as described in claim 1, wherein the tilt drive mechanism tilts the sample holder about a flip axis as a central axis, and tilts the sample holder about a swing axis perpendicular to the flip axis as a central axis.

3. A charged particle beam device as described in claim 1, further comprising a first current measuring unit electrically connected to the second terminal and the control unit, wherein when the electron beam is irradiated onto the sample, the first current measuring unit measures the current flowing from the sample via the sample holder and the second terminal as a current signal, and the image forming unit is capable of forming an absorbed current image of the sample from the scanning signal of the electron beam and the current signal of the first current measuring unit.

4. A method for preparing a sample using the charged particle beam device described in claim 3, comprising: (a) a step of irradiating an observation surface of the sample with the ion beam and processing the observation surface; (b) after the step (a), a step of tilting the sample using the tilt drive mechanism, irradiating the observation surface with the ion beam and processing the observation surface; and (c) after the step (b), a step of irradiating the observation surface with the electron beam and obtaining a first absorbed current image of the sample.

5. A method for preparing a sample as described in claim 4, comprising repeating steps (a), (b) and (c), and completing the processing of the observation surface based on a change in the current signal of the first current measuring unit.

6. A charged particle beam apparatus as defined in claim 1, further comprising: a probe capable of contacting the sample held in the sample holder; and a second current measuring unit electrically connected to the probe and the control unit, wherein the control unit controls the probe; when the sample is irradiated with the electron beam, the probe contacts the sample and the second terminal is connected to ground potential, the second current measuring unit measures the current flowing from the sample via the probe as a current signal; and the image forming unit is capable of forming an electron beam induced current image of the sample from the scanning signal of the electron beam and the current signal of the second current measuring unit.

7. A charged particle beam device as described in claim 6, wherein the image forming section is capable of forming an SEM image from the signal detected by the detector, and is capable of forming a photographed image by superimposing the electron beam induced current image and the SEM image.

8. A method for preparing a sample using the charged particle beam device described in claim 7, comprising the steps of: (a) irradiating an observation surface of the sample with the ion beam and processing the observation surface; (b) after step (a), tilting the sample using the tilt drive mechanism, irradiating the observation surface with the ion beam and processing the observation surface; (c) after step (b), irradiating the observation surface with the electron beam and obtaining a first electron beam induced current image of the observation surface and a first SEM image of the observation surface; and (d) after step (c), obtaining an image in which the first electron beam induced current image and the first SEM image are superimposed.

9. A method for preparing a sample as described in claim 8, comprising repeating steps (a), (b), (c) and (d), and completing the processing of the observation surface based on a change in the current signal of the second current measuring unit.

10. A charged particle beam apparatus as described in claim 1, further comprising: a probe capable of contacting the sample held in the sample holder; and a third current measurement unit electrically connected to the probe and the control unit, wherein the control unit controls the probe; when the sample is irradiated with the electron beam, the probe contacts the sample and the second terminal is connected to ground potential, the third current measurement unit measures the current flowing from the sample via the probe as a current signal, and the image formation unit is capable of forming an absorbed current image of the sample from the scanning signal of the electron beam and the current signal of the third current measurement unit.

11. A method for preparing a sample using the charged particle beam device described in claim 10, comprising: (a) a step of irradiating an observation surface of the sample with the ion beam and processing the observation surface; (b) after step (a), a step of tilting the sample using the tilt drive mechanism, irradiating the observation surface with the ion beam and processing the observation surface; and (c) after step (b), a step of irradiating wiring formed on the surface of the sample with the electron beam and acquiring a second absorbed current image of a conductor pattern connected to the wiring.

12. A method for preparing a sample as described in claim 11, comprising repeating steps (a), (b) and (c) and completing the processing of the observation surface based on a change in the current signal of the third current measuring unit.

13. A charged particle beam device as described in claim 1, further comprising: a needle provided for attaching and detaching the sample to the sample holder; and a fourth current measuring unit electrically connected to the needle and the control unit, wherein the control unit controls the needle; when the electron beam is irradiated to the needle, the second terminal is connected to ground potential, the fourth current measuring unit measures the current flowing from the needle as a current signal, and the image forming unit can form an absorption current image of the needle from the scanning signal of the electron beam and the current signal of the fourth current measuring unit.

14. A method for preparing a sample using a charged particle beam device as described in claim 13, comprising: (a) a step of connecting the sample connected to the needle to a columnar portion of the sample holder by deposition; and (b) after step (a), a step of irradiating the ion beam to the connection point between the needle and the sample and detaching the needle from the sample, wherein steps (a) and (b) are performed while irradiating the needle with the electron beam and acquiring a third absorption current image of the needle, and wherein in step (a), it is determined that the sample is connected to the columnar portion based on a change in the current signal of the fourth current measurement unit, and in step (b), it is determined that the needle is detached from the sample based on a change in the current signal of the fourth current measurement unit.

15. A method for preparing a sample as recited in claim 14, comprising the steps of: (d) after step (c), tilting the sample using the tilt drive mechanism while the sample is connected to the columnar portion, and irradiating the sample with the ion beam to process the sample into a conical shape; (e) after step (d), connecting the sample to the needle by deposition; (f) after step (e), irradiating the connection point between the columnar portion and the sample with the ion beam, and detaching the sample connected to the needle from the columnar portion; steps (e) and (f) are performed while irradiating the needle with the electron beam and acquiring a fourth absorption current image of the needle; and in step (e), determining that the sample is connected to the needle based on a change in the current signal of the fourth current measurement unit; and in step (f), determining that the sample is detached from the columnar portion based on a change in the current signal of the fourth current measurement unit.

16. A charged particle beam device as claimed in claim 1, further comprising a retarding power supply, wherein when the sample is irradiated with the electron beam, the second terminal is electrically connected to the retarding power supply and a retarding potential is supplied from the retarding power supply to the second terminal.

17. A method for preparing a sample using the charged particle beam device described in claim 16, comprising: (a) a step of irradiating an observation surface of the sample with the ion beam and processing the observation surface; (b) after step (a), a step of tilting the sample using the tilt drive mechanism, irradiating the observation surface with the ion beam and processing the observation surface; and (c) after step (b), a step of irradiating the observation surface with the electron beam and acquiring a second SEM image of the observation surface while the retarding potential is being supplied to the sample via the second terminal.

Images