TW201835964A - Charged particle beam device and sample processing method capable of uniformly irradiating the entire miniature sample piece having a reduced sample thickness with a charged particle beam and capable of precisely grasping a processing end point during processing - Google Patents

Abstract

The present invention provides a charged particle beam device and a sample processing method, capable of uniformly irradiating the entire miniature sample piece having a reduced sample thickness with a charged particle beam and capable of precisely grasping a processing end point during processing. The charged particle beam device which irradiates a sample with a charged particle beam to produce a miniature sample piece is characterized in that the charged particle beam device comprises a charged particle beam tube configured to irradiate the sample with the charged particle beam; a sample room configured to accommodate the charged particle beam tube; and a sample piece holder configured to hold the sample. When the miniature sample piece having a reduced thickness of a portion of the sample is formed through the charged particle beam device, a portion adjacent to a thinned portion of the miniature sample piece is formed with an inclination part which is inclined relative to the thinned portion.

Description

Charged particle beam device and sample processing method

The present invention relates to a charged particle beam device for processing a sample using a charged particle beam and a sample processing method using the charged particle beam.

For example, as a method of analyzing the internal structure of a sample such as a semiconductor element or performing stereoscopic observation, a method for observing a cross-section is known, which uses a lens barrel equipped with a Focused Ion Beam (FIB) and an electron. A beam (Electron Beam; EB) lens barrel composite device performs FIB-based cross-section formation processing and observation of the cross-section with a scanning electron microscope (Scanning Electron Microscope: SEM) (for example, refer to Patent Document 1). This cross-section processing observation method is known to construct a three-dimensional image by repeating the FIB-based cross-section formation processing and the SEM-based cross-section observation. In this method, the three-dimensional shape of the object sample can be analyzed in detail from various directions based on the reconstructed three-dimensional stereo image. In addition, there is an advantage that other methods such as an arbitrary cross section of an object sample can be reproduced. On the other hand, SEM has a limit in observation of high magnification (high resolution) in principle, and the information obtained is also limited to the vicinity of the sample surface. Therefore, an observation method is also known in which a transmission electron microscope (TEM) that transmits electrons is used for a sample processed into a thin film in order to perform high-resolution observation at a higher magnification. The above-mentioned FIB-based cross-section forming process is also effective in the production of thin-filmed fine samples (hereinafter, sometimes referred to as minute sample pieces) used for observation by TEM. Conventionally, when making a small sample piece used for observation by TEM, for example, by irradiating a charged particle beam to a front end portion of a sample in a thickness direction of the sample, the thickness of the sample is reduced and the thickness thereof is reduced. To make tiny test pieces. For example, when thinning a sample obtained by stacking a plurality of elements on a semiconductor substrate in the thickness direction, the SEM image of the processed cross section is observed while the charged particle beam is irradiated, and the number of elements exposed in the processed cross section is counted. , Thus grasp the desired processing end point. On the other hand, in order to reduce the processing stripe pattern (curtain effect) along the irradiation direction of the charged particle beam generated by the processing using the charged particle beam, it may be performed by tilting it from the thickness direction of the sample. It is performed by irradiating a charged particle beam in a direction of (see, for example, Patent Document 2). Patent Document 1: Japanese Patent Application Laid-Open No. 2008-270073 Patent Document 2: Japanese Patent Application Laid-Open No. 9-186210 However, in the processing method (thinning method) of the sample described above, the thinned portion of the sample Since it is etched, a portion adjacent to the portion is not etched, so a step difference of 90 ° is generated. Furthermore, when a charged particle beam is irradiated from a direction inclined with respect to the processing surface of the thinned portion in order to cope with the curtain effect as described above, the above-mentioned adjacent portion shields the charged particle beam, so that the charged particle beam cannot be irradiated. Shadow area. Therefore, it is necessary to consider the shadow area that the charged particle beam cannot irradiate to determine the processing width. Therefore, it is necessary to irradiate the charged particle beam in comparison with a desired processing range with a larger processing width. For this reason, the processing time of a sample becomes long, and there exists a possibility that a micro sample piece of a desired shape may not be produced. In addition, when thinning a sample formed by stacking a plurality of elements in a thickness direction on a semiconductor substrate, when counting the number of elements exposed due to processing in order to grasp the processing end point, the above-mentioned shadow may be The contrast of the machined surface is reduced under the influence of the area, the number of components cannot be accurately counted, and the processing end point cannot be accurately grasped.

[Problems to be Solved by the Invention] The present invention has been made in view of the above circumstances, and an object thereof is to provide a charged particle beam device and a method for processing a sample. The charged particle beam device can reduce The sample piece is uniformly irradiated with the charged particle beam, and the processing end point at the time of processing can be clearly grasped. [Means for Solving the Problems] In order to solve the problems described above, the embodiment of the present embodiment provides the following charged particle beam device and sample processing method. That is, the charged particle beam device of the present invention is a charged particle beam device that irradiates a charged particle beam toward a sample to make a minute sample piece, and is characterized in that the charged particle beam device includes a charged particle beam tube that can face The sample irradiates a charged particle beam; a sample chamber containing the charged particle beam lens barrel; and a sample piece holder capable of holding the sample, which reduces the formation of the charged particle beam by the charged particle beam. In the case of a thin sample piece having a thickness of a part of the sample, a portion adjacent to the thinned portion of the small sample piece forms an inclined portion inclined with respect to the thinned portion. According to the charged particle beam device of the present invention, an inclined portion inclined with respect to the thinned portion is formed by a portion adjacent to the thinned portion of the minute sample piece, and a cross-sectional shape ratio of the element exposed in the inclined portion is in a direction in which the element is extended. The cross-sectional shape of the right-angled cross section is larger and more vividly visible, so that the number of components can be accurately counted. This makes it possible to easily and reliably determine the processing end point of the sample by the charged particle beam. In addition, the present invention is characterized in that the charged particle beam device irradiates an argon ion beam so as to be parallel to the inclined portion. The sample processing method of the present invention is a sample processing method in which a charged particle beam is irradiated toward a sample to make a small sample piece having a reduced thickness in a part of the sample area. The sample processing method is characterized in that: A slope forming process is provided. In the slope forming process, a plurality of removed areas are formed in the thickness direction of the sample by irradiation with the charged particle beam, and the removed areas have a predetermined thickness direction. And the processing width in the width direction perpendicular to the thickness direction, the processing width is gradually reduced each time the overlapped area is overlapped, thereby reducing the thickness of the micro sample piece in comparison with the thinned portion of the micro sample piece. The adjacent portion forms an inclined portion that is inclined with respect to the thinned portion. According to the sample processing method of the present invention, since an inclined portion inclined with respect to the thinned portion can be formed in a portion adjacent to the thinned portion of the minute sample piece, in the subsequent process, during the irradiation and processing of the sample When the reprocessed beams with different irradiation angles of the charged particle beams used are used, it is possible to eliminate the shadow region where the argon ion beam is not irradiated to the root portion of the minute sample piece, so that the entire region of the minute sample piece can be reliably irradiated Ion beam. Thereby, the processing stripe pattern can be reduced in the entire area of the minute sample piece, and a minute sample piece with a clear observation image can be obtained. In addition, the present invention is characterized in that the processing thickness and the processing width of each of the removed regions in the inclined portion forming process are determined with reference to an SEM image of the inclined portion obtained by a scanning electron microscope. In addition, the present invention is characterized in that the sample is formed by superposing a plurality of buried layers in the thickness direction inside the substrate. In the inclined portion forming process, the number of the buried layers exposed in the inclined portion is counted using the SEM image to determine a processing end point. The sample processing method is characterized in that, in the inclined portion forming process, the thinned portion and the inclined portion that is a portion adjacent to the thinned portion are made 10 ° or more and less than 90 ° from each other. Tilt within range. In addition, the present invention is characterized in that the sample processing method further includes an argon beam irradiation process in which argon ions are irradiated toward the minute sample piece so as to be parallel to the inclined portion. bundle. According to the present invention, it is possible to provide a charged particle beam device and a sample processing method that can uniformly irradiate a charged particle beam over the entire small sample piece with a reduced thickness of the sample and can clearly understand the processing end point during processing.

Hereinafter, a charged particle beam apparatus and a sample processing method using the charged particle beam apparatus as an embodiment of the present invention will be described with reference to the drawings. In addition, each embodiment shown below is specifically described in order to better understand the gist of the invention, and the invention is not limited thereto unless otherwise specified. In addition, in order to easily understand the features of the present invention, the drawings used in the following description may be enlarged and shown as a main part for convenience, and the dimensional ratios and the like of the constituent elements may not necessarily be the same as the actual ones. FIG. 1 is a schematic configuration diagram showing a charged particle beam device according to an embodiment of the present invention. As shown in FIG. 1, the charged particle beam device 10 according to the embodiment of the present invention includes a sample chamber 11 capable of maintaining the inside in a vacuum state, and a stage 12 capable of holding a bulk sample V and A specimen holder P for holding the specimen S is fixed inside the specimen chamber 11; and a stage driving mechanism 13 that drives the stage 12. The pseudo-charged particle beam device 10 includes a converged ion beam irradiation optical system 14 that irradiates an irradiation target in a predetermined irradiation area (that is, a scanning range) inside the sample chamber 11 with a charged particle beam such as a converged ion beam (FIB). The charged particle beam device 10 includes an electron beam irradiation optical system 15 that irradiates an irradiation target in a predetermined irradiation area inside the sample chamber 11 with an electron beam (EB). The charged particle beam device 10 includes a detector 16 that detects secondary charged particles (secondary electrons, secondary ions) R generated from an irradiation target by irradiation of a charged particle beam or an electron beam. The krypton charged particle beam device 10 includes a gas ion beam optical system 18 that irradiates an irradiation target in a predetermined irradiation area inside the sample chamber 11 with a gas ion beam (GB). The converged ion beam irradiation optical system 14, the electron beam irradiation optical system 15, and the gas ion beam optical system 18 are arranged so that their respective beam irradiation axes can cross at substantially one point on the stage 12. That is, when the sample chamber 11 is viewed from the side, the condensing ion beam optical system 14 is arranged in the vertical direction, and the electron beam irradiation optical system 15 and the gas ion beam optical system 18 are inclined at, for example, 45 ° with respect to the vertical direction. Direction configuration. With such an arrangement, when the sample chamber 11 is viewed from the side, the beam irradiation axis of the gas ion beam (GB) is, for example, perpendicular to the beam irradiation axis of the electron beam (EB) irradiated from the electron beam irradiation optical system 15. Intersecting directions. The krypton-charged particle beam device 10 includes a gas supply unit 17 that supplies a gas G to a surface of an irradiation target. The gas supply unit 17 is specifically a nozzle 17 a or the like having an outer diameter of about 200 μm. The charged particle beam device 10 includes a gas supply unit 17 that supplies a gas G to a surface of an irradiation target. The gas supply unit 17 is specifically a nozzle 17 a or the like having an outer diameter of about 200 μm. The charged particle beam device 10 includes a sample piece transfer unit 19 that removes a sample piece S from a sample V fixed on the stage 12, holds the sample piece S, and transfers the sample piece S to a sample piece holder. The needle 19a on P and the needle driving mechanism 19b that drives the needle 19a to convey the sample piece S, and an absorption current detector 20 that detects the inflow current (also referred to as the absorption current) of the charged particle beam flowing into the needle 19a, and The incoming current signal is sent to a computer for imaging. The charged particle beam device 10 includes a display device 21, a computer 22, and an input device 23 that display image data and the like based on the secondary charged particles R detected by the detector 16. In addition, the irradiation targets of the convergent ion beam irradiation optical system 14 and the electron beam irradiation optical system 15 are the sample V, the sample piece S fixed on the stage 12, the needle 19a, and the sample piece holder existing in the irradiation area. P and so on. The charged particle beam device 10 can perform imaging of an irradiated portion, various processes based on sputtering (excavation, trimming processing, and the like), and depositing a film by scanning the charged particle beam while irradiating the surface of an irradiation target. deposited film). The charged particle beam device 10 can execute cutting of a sample piece S from a sample V and formation of a small sample piece Q used for TEM-based observation from the sample piece S (see FIG. 3: for example, a thin sample, Needle-shaped samples, etc.), processing of electron beam analysis sample pieces. The charged particle beam device 10 can reduce the thickness of, for example, the front end portion of the sample piece S placed on the sample piece holder P to a desired thickness (for example, 5 to 100 nm, etc.) suitable for transmission observation of a transmission electron microscope, thereby obtaining observation. Used tiny sample piece Q. The charged particle beam device 10 can perform observation of the surface of the irradiation target by scanning the surface of the irradiation target such as the sample sheet S, the needle 19a, and the like while scanning the charged particle beam or the electron beam. The chirped current detector 20 has a preamplifier that amplifies the current flowing into the needle and sends it to the computer 22. Based on the signals synchronized with the needle inflow current detected by the absorption current detector 20 and the scanning of the charged particle beam, a needle-shaped absorption current image can be displayed on the display device 21, and the needle shape and tip position can be determined. The sample chamber 11 is configured to be able to be exhausted by an exhaust device (not shown) until the inside is in a desired vacuum state and to maintain the desired vacuum state. The ballast stage 12 holds the sample V. The stage 12 includes a holder fixing table 12 a that holds the sample holder P. The holder fixing table 12 a may have a structure capable of mounting a plurality of sample holders P. The stage driving mechanism 13 is housed inside the sample chamber 11 in a state of being connected to the stage 12 and moves the stage 12 relative to a predetermined axis based on a control signal output from the computer 22. The stage driving mechanism 13 includes at least a moving mechanism 13 a that moves the stage 12 in parallel with the X-axis and the Y-axis that are parallel to the horizontal plane and perpendicular to each other, and the Z-axis in the vertical direction that is perpendicular to the X-axis and Y-axis. The stage driving mechanism 13 includes a tilt mechanism 13 b that tilts the stage 12 about the X-axis or Y-axis, and a rotation mechanism 13 c that rotates the stage 12 about the Z-axis. The condensed ion beam irradiation optical system 14 is fixed to the sample chamber 11 in such a manner that a beam emitting portion (not shown) is positioned above the vertical direction of the stage 12 in the irradiation area inside the sample chamber 11. The side faces the stage 12 and the optical axis is parallel to the vertical direction. Thereby, an irradiation target such as the sample V, the sample piece S placed on the stage 12, and the needle 19a existing in the irradiation area can be irradiated with the charged particle beam from above in the vertical direction and downward. In addition, the charged particle beam device 10 may include another ion beam irradiation optical system instead of the condensed ion beam irradiation optical system 14 as described above. The ion beam irradiation optical system is not limited to an optical system that forms a convergent beam as described above. The ion beam irradiation optical system may be, for example, a projection type ion beam irradiation optical system in which a shaped mask having a shaped opening is provided in the optical system to form a shaped beam having a stencil mask opening. According to such a projection-type ion beam irradiation optical system, a shaped beam having a shape corresponding to a processing area around the sample piece S can be formed with high accuracy, thereby reducing processing time. The krypton-condensing ion beam irradiation optical system 14 includes an ion source 14 a that generates ions, and an ion optical system 14 b that condenses and deflects ions extracted from the ion source 14 a. The ion source 14a and the ion optical system 14b are controlled based on a control signal output from the computer 22, and the irradiation position and irradiation conditions of the charged particle beam are controlled by the computer 22. The europium ion source 14a is, for example, a liquid metal ion source using liquid gallium, a plasma ion source, a gas field ionization ion source, or the like. The ion optical system 14b includes, for example, a first electrostatic lens such as a condenser lens, a second electrostatic lens such as an electrostatic deflector, and an objective lens. When a plasma-type ion source is used as the ion source 14a, high-speed processing of a large current beam can be realized, and it is suitable for taking out a large-sized sample piece S. For example, by using argon ions as a gas-field ionization-type ion source, it is also possible to irradiate an argon ion beam from the focused ion beam irradiation optical system 14. The electron beam irradiation optical system 15 is fixed to the sample chamber 11 in such a manner that a beam emitting portion (not shown) is tilted in the vertical direction with respect to the stage 12 in the irradiation area inside the sample chamber 11. The inclined direction at a predetermined angle (for example, 60 °) faces the stage 12 and the optical axis is parallel to the inclined direction. Thereby, the irradiation target such as the sample V, the sample piece S, and the needle 19 a existing in the irradiation area, which is fixed on the stage 12, can be irradiated with the electron beam from above in the oblique direction and downward. The krypton electron beam irradiation optical system 15 includes an electron source 15a that generates electrons, and an electron optical system 15b that converges and deflects electrons emitted from the electron source 15a. The electron source 15a and the electron optical system 15b are controlled based on a control signal output from the computer 22, and the irradiation position and irradiation conditions of the electron beam are controlled by the computer 22. The electron optical system 15b includes, for example, an electromagnetic lens, a deflector, and the like. In addition, the arrangement of the electron beam irradiation optical system 15 and the condensing ion beam irradiation optical system 14 may be changed, the electron beam irradiation optical system 15 may be arranged in a vertical direction, and the polyion beam irradiation optical system 14 may be arranged relative to The vertical direction is tilted by a predetermined angle. The krypton gas ion beam optical system 18 irradiates a gas ion beam (GB) such as an argon ion beam. The gas ion beam optical system 18 can ionize argon gas and irradiate it at a low acceleration voltage of about 1 kV. Since such a gas ion beam (GB) has a lower convergence property than a converged ion beam (FIB), the etching rate of the sample piece S and the minute sample piece Q becomes low. Therefore, it is suitable for precise finishing of the test piece S and the minute test piece Q. The detector 16 detects the intensity of the secondary charged particles (secondary electrons, secondary ions) R radiated from the irradiation target when irradiating the irradiation target such as the sample V, the sample piece S, and the needle 19a with a charged particle beam or an electron beam. (That is, the amount of secondary charged particles), and outputs information on the detected amount of the secondary charged particles R. The detector 16 is disposed inside the sample chamber 11 at a position capable of detecting the amount of the secondary charged particles R. For example, the detector 16 is fixed at a position obliquely above the irradiation target such as the sample V and the sample piece S in the irradiation area. Sample room 11. The krypton gas supply unit 17 is fixed to the sample chamber 11 and is disposed inside the sample chamber 11 so as to have a gas injection unit (also referred to as a nozzle) and face the stage 12. The gas supply unit 17 can supply the sample V and the sample piece S to selectively promote the charged particle beam (convergent ion beam) to the sample V and the sample piece S depending on the material of the sample V and the sample piece S. An etching gas used for etching, a deposition gas used to form a deposited film of a deposit such as a metal or an insulator on the surfaces of the sample V and the sample piece S, and the like.针 The needle driving mechanism 19b constituting the sample piece displacement unit 19 is stored in the sample chamber 11 in a state of being connected to the needle 19a, and the needle 19a is displaced according to a control signal output from the computer 22. The needle driving mechanism 19b is provided integrally with the stage 12. For example, when the stage 12 is rotated about the tilt axis (that is, the X-axis or the Y-axis) by the tilt mechanism 13b, it moves integrally with the stage 12. The needle driving mechanism 19b includes a moving mechanism (not shown) that moves the needle 19a in parallel along the three-dimensional coordinate axis, and a rotating mechanism (not shown) that rotates the needle 19a about the central axis of the needle 19a. The three-dimensional coordinate axis is independent of the orthogonal three-axis coordinate system of the sample stage. In the orthogonal three-axis coordinate system that is a two-dimensional coordinate axis parallel to the surface of the stage 12, the surface of the stage 12 is inclined. In the state of rotation and rotation, the coordinate system is tilted and rotated. The computer 22 controls at least the stage driving mechanism 13, the focused ion beam irradiation optical system 14, the electron beam irradiation optical system 15, the gas supply unit 17, and the needle driving mechanism 19b.电脑 In addition, the computer 22 is disposed outside the sample chamber 11, and is connected to a display device 21 and input devices 23 such as a mouse and a keyboard that output signals corresponding to input operations by the operator. The computer 22 uniformly controls the operation of the charged particle beam device 10 based on a signal output from the input device 23 or a signal generated by a preset automatic operation control process. The computer 22 converts the detection amount of the secondary charged particles R detected by the detector 16 into a luminance signal corresponding to the irradiation position while scanning the irradiation position of the charged particle beam, and according to the two-dimensional position distribution of the detection amount of the secondary charged particles R Generate image data representing the shape of the irradiation target. In the absorption current image mode, the computer 22 detects the absorption current flowing in the needle 19a while scanning the irradiation position of the charged particle beam, thereby generating a representation of the needle 19a based on the two-dimensional position distribution of the absorption current (absorption current image). The shape of the sink current image data. The computer 22 displays a screen for performing operations such as zooming in, zooming out, moving, and rotating the image data together with the generated image data on the display device 21. The computer 22 displays a screen for performing various settings such as mode selection and processing settings in automatic sequence control on the display device 21. A sample processing method according to the present invention using the charged particle beam device 10 having the above-described structure will be described. FIG. 2 and FIG. 3 are explanatory diagrams showing a sample processing method in steps. In addition, in the following embodiments, as a sample processing method, a thin sample piece supported on a sample piece holder P by a charged particle beam is formed into a thin sample piece for TEM observation. An example of Q will be explained. In addition, as shown in FIG. 2 (a), it is assumed that the sample piece S is a sample obtained by cutting out a region in which a plurality of elements 31, 31, ... are formed on a sample V (see FIG. 1) composed of a semiconductor substrate. In the sheet, the direction in which the elements 31, 31,... Are arranged is referred to as a thickness direction T, and the extending direction of the element 31 that is perpendicular to the thickness direction T is referred to as a width direction W. A direction perpendicular to the thickness direction T and the width direction W is referred to as a processing direction D. First, a sample piece S as a small area containing an observation object is cut out from a sample V (see FIG. 1) made of a semiconductor substrate by FIB processing. Then, the sample piece holder P (see FIG. 1) is used to support the sample piece S as a processing target using the needle 19 a (see FIG. 1) so that the thickness direction of the semiconductor substrate is the vertical direction (processing direction D). Then, as shown in FIG. 2 (b), an irradiation area is set for the sample sheet S, and FIB is irradiated in the processing direction D from the focused ion beam irradiation optical system 14 (see FIG. 1). Then, a first removal region E1 having a predetermined processing thickness in the thickness direction T of the test piece S and a processing width W1 in the width direction W is formed. As a result, the end portion E1e on the root side of the first removal region E1, for example, exposes the end surface of one element 31. Next, as shown in FIG. 2 (c), FIB is irradiated to the position overlapping the first removal area E1 in the thickness direction T, that is, the position offset from the first removal area E1 in the thickness direction T by a predetermined processing thickness. A second removal area E2 is formed. At this time, the processing width W2 in the width direction W is set to a width that is shorter than the processing width W1 by a predetermined reduction width ΔW. As a result, the end portion E2e on the root side of the second removal region E2 is positioned closer to the center side in the width direction W than the end portion E1e on the root side of the first removal region E1. In addition, as shown in FIG. 3 (a), the position overlapping the n-th removal region En formed in the thickness direction T is shifted from the n-th removal region En in the thickness direction T by a predetermined processing thickness. The FIB is irradiated to form the (n + 1) th removal region E (n + 1). At this time, the processing width W (n + 1) in the width direction W is set to a width that is shorter than the processing width Wn of the n-th removal region En by a predetermined reduction width ΔW. In this way, the sample sheet S is irradiated with FIB in the processing direction D, and a plurality of removed regions that reduce the processing width are gradually formed in the thickness direction T to overlap, thereby forming a pattern that reduces the thickness T of the sample sheet S. Thick sample piece Q. (2) By forming such a plurality of removal regions that reduce the processing width in stages, the thin sample piece Q is formed with a thinned portion Qs having a reduced thickness. Further, an inclined portion (a portion adjacent to the thinned portion) C is formed in a portion adjacent to the thinned portion Qs, that is, a portion connected to an end portion on the root side of each removal region (inclined portion forming process). The inclined portion C is, for example, an inclined surface inclined within a range of 10 ° or more and less than 90 ° with respect to the thickness direction T. For example, the surface of the inclined portion C may be formed parallel to the irradiation angle of the argon ion beam. As an example, in the present embodiment, the inclined portion C is an inclined surface inclined by 20 ° with respect to the thickness direction T. Here, in a range of 10 ° or more and less than 90 °, by radiating the beam at a small incident angle smaller than 90 °, it is possible to make the damage layer of the sample shallower when the beam is incident. Accordingly, since the damaged layer is made shallow, even a sample with a fine element size can clearly grasp the processing end point during processing. In addition, in the embodiment shown in FIGS. 2 and 3, the FIB is scanned and irradiated so that the processing width Wn in the width direction W of the sample piece S is gradually reduced to form the inclined portion (and The thinned portion is adjacent to the C), but the FIB scanning method is not limited to this. For example, in the example of the FIB scan shown in FIG. 4, the processing width Wn of the removal region En in the width direction W of the sample piece S as the thinned portion Qs is made constant. Then, the FIB is continuously scanned from the root side of each removal area En to a direction inclined with respect to the thickness direction T within a range of 10 ° or more and less than 90 °. Thereby, the inclined portion C is formed in a region where the FIB scans in a direction inclined with respect to the thickness direction T. The processing width Wn along such an inclined portion C gradually increases. Here, the FIB scanning method uses a vector scan in which the scanning direction of the FIB is changed from the width direction of the sample piece S to a direction inclined with respect to the thickness direction T. In addition, a first rectangular irradiation area may be set in the width direction of the sample piece S, a second rectangular irradiation area may be set in a direction inclined with respect to the thickness direction T, and a raster scan (raster scan) may be used in each irradiation area. ) Or bitmap scan. In addition, the scanning direction of the FIB in the trapezoidal area divided by the thinned portion Qs of the minute sample piece Q and the inclined portion C as a portion adjacent to the thinned portion Qs is not particularly limited as long as it can be formed as The slanted portion C of the portion adjacent to the thinned portion Qs may also scan the FIB in any direction to form a removal region. As described above, in the process of forming a plurality of removed regions in which the processing width is gradually reduced, the EB is irradiated from the electron beam irradiation optical system 15 at an arbitrary timing to obtain an SEM image of the inclined portion C. Then, by observing the obtained SEM image and counting the number of the elements 31, 31,... Exposed in the inclined portion C, the processing end point of the thickness direction T of the FIB can be determined. The cross-sectional shape of the elements 31, 31, ... exposed in the inclined portion C can be seen, for example, larger and more clearly than the cross-sectional shape of the elements exposed in the cross-section in the thickness direction T. Therefore, the elements 31, 31, ... The number is counted. In addition, for example, the computer 22 can automatically count the elements 31, 31, ... exposed from the sloping portion C from the acquisition of the SEM image, and feed back the results to the FIB irradiation conditions for the specimen S, thereby enabling automation. A minute sample piece Q having an inclined portion C connected to the root side is formed. As a specific example of such an automatic processing end point detection method, the number of design elements 31, 31,... Appearing in the observation target position (exposed in the inclined portion C) is input to the computer 22 in advance. The predetermined number of occurrences of such elements 31 can be grasped based on design data and the like of the integrated circuit formed in the sample V. Then, the image comparison software and the like executed by the computer 22 count the number of the elements 31 appearing in the inclined portion C by repeatedly forming the FIB-based irradiation removal area and acquiring the irradiation SEM image. When the predetermined number of appearances of the element 31 input to the computer 22 in advance coincides with the number of the elements 31 appearing on the inclined portion C based on the actual SEM image acquisition, this is recognized as the processing end point and the FIB irradiation is ended. In addition, as another specific example of an automated processing endpoint detection method, when a sample piece S is cut out from a sample (semiconductor substrate) V (see FIG. 1) by FIB, an SEM image of a sidewall of the sample piece S is obtained. image. Then, an image comparison software or the like executed by the computer 22 counts the number of the elements 31 exposed in the side wall of the sample piece S. Alternatively, the number of elements 31 exposed in the cut end surface of the sample V after the sample piece S is cut out, or the sample piece S based on the design data of the integrated circuit formed on the sample V may be cut. The number of components 31 on the design of the outgoing part is counted. In this way, the actual number of elements 31 appearing on the inclined portion C by repeating the formation of the removal area of the FIB-based irradiation and the acquisition of the irradiation SEM image is subtracted from the total number of the elements 31 of the sample piece S recognized by the computer 22. When the number of elements matches the number of elements 31 to be left in the sample piece S input to the computer 22 in advance, this is recognized as the end point of processing and the FIB irradiation is terminated. Next, as shown in FIG. 3 (b), for example, the minute sample piece Q is irradiated with a gas ion beam, such as an argon ion beam, at an angle parallel to the surface of the inclined portion C, thereby reducing processing caused by processing using FIB. Stripe pattern (curtain effect) (argon beam irradiation process). (2) In this argon beam irradiation process, argon gas is ionized from the gas ion beam optical system 18 (see FIG. 1), and the entire area of the minute sample piece Q is irradiated with a low acceleration voltage of, for example, about 1 kV. At this time, it is preferable to irradiate the EB from the electron beam irradiation optical system 15 toward the minute sample piece Q, and perform a finishing process of the minute sample piece Q based on the obtained SEM image. The detection of the processing end point at this time can also be applied to the processing end point detection process at the time of processing of the micro sample piece Q based on the FIB described above. This makes it possible to automate the argon beam irradiation process. In such an argon beam irradiation process, as a portion adjacent to the root portion of the minute sample piece Q, an inclined portion C inclined at an angle ranging from 10 ° to 90 ° with respect to the thickness direction T is formed. Therefore, it is possible to uniformly irradiate an argon ion beam over the entire area of the minute sample piece Q that is reduced in thickness by reducing the thickness of the sample piece S. That is, as shown in FIG. 1, the gas ion beam optical system 18 is arranged such that, when the sample chamber 11 is viewed from the side, the beam irradiation axis of the gas ion beam (GB) is, for example, electrons irradiated from the electron beam irradiation optical system 15 The beams of the beam (EB) irradiate the directions in which the axes intersect perpendicularly. Therefore, when the thickness direction T is, for example, at right angles to the width direction W of the minute sample piece Q, a shadow area in which the argon ion beam is not radiated to the root portion of the minute sample piece Q is generated. However, as in the present embodiment, by forming an inclined portion C that is inclined in a range of, for example, 10 ° or more and less than 90 ° in the micro sample piece Q in accordance with an argon ion beam irradiated at an angle inclined with respect to the thickness direction T, The shadow area where the argon ion beam is not irradiated to the root portion of the minute sample piece Q can be eliminated, and the entire area of the minute sample piece Q can be reliably irradiated with the argon ion beam. This makes it possible to form a sample sheet for TEM observation in which the processing fringe pattern is reduced in the entire area of the minute sample sheet Q and a clear observation image can be obtained. In addition, as shown in FIG. 3 (c), it is also possible to form a plurality of removal regions in which the processing width in the width direction W is gradually reduced from a direction opposite to the processing direction in the thickness direction T described above, thereby forming a substrate having a thickness from A thin sample piece Q with a reduced thickness Qs on both sides. Although the embodiments of the present invention have been described, these embodiments are presented as examples and are not meant to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and spirit of the invention, and within the scope of the invention described in the claims and their equivalents.

10‧‧‧ Charged particle beam device

11‧‧‧Sample room

12‧‧‧stage (sample stage)

13‧‧‧stage drive mechanism

14‧‧‧Converging ion beam irradiation optical system (charged particle beam irradiation optical system)

15‧‧‧ electron beam irradiation optical system (charged particle beam irradiation optical system)

16‧‧‧ Detector

17‧‧‧ Gas Supply Department

18‧‧‧Gas ion beam irradiation optical system (charged particle beam irradiation optical system)

19a‧‧‧pin

19b‧‧‧needle drive mechanism

20‧‧‧ Sink Current Detector

21‧‧‧display device

22‧‧‧Computer

23‧‧‧Input device

33‧‧‧Sample stage

34‧‧‧Columnar

C‧‧‧inclined

P‧‧‧ sample holder

Q‧‧‧Small sample piece

R‧‧‧ secondary charged particles

S‧‧‧Sample

V‧‧‧Sample

FIG. 1 is a configuration diagram of a charged particle beam device according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing a sample processing method in steps. FIG. 3 is an explanatory diagram showing a sample processing method in steps. FIG. 4 is an explanatory diagram showing another example of a sample processing method.

Claims (7)

A charged particle beam device, which irradiates a charged particle beam toward a sample to make a small sample piece, is characterized by having: a charged particle beam lens barrel capable of irradiating the charged particle beam toward the sample; a sample chamber, which Storing the charged particle beam lens barrel; and a sample piece holder capable of holding the sample, (i) when forming a small sample piece having a reduced thickness of a part of the sample area by the charged particle beam, A portion adjacent to the thinned portion of the minute sample piece forms an inclined portion that is inclined with respect to the thinned portion. The charged particle beam device according to item 1 of the scope of patent application, wherein the charged particle beam device irradiates an argon ion beam in a manner parallel to the inclined portion. A sample processing method is a method of processing a sample by irradiating a charged particle beam toward a sample to make a small sample piece having a reduced thickness in a part of the sample area, and characterized in that it has a slope forming process, In this inclined portion forming process, a plurality of removal areas are formed in the thickness direction of the sample by irradiation with the charged particle beam, and the removal areas have a predetermined processing thickness in the thickness direction and a plurality of removal areas. The processing width in the width direction, which is perpendicular to the thickness direction, is gradually reduced each time the overlapped area is removed, so that a portion adjacent to the thinned portion of the minute sample piece is formed to be opposite to the thinned portion. The thinned portion is an inclined portion inclined. The sample processing method according to item 3 of the scope of patent application, wherein: (1) the processing thickness and the processing width of each of the removed regions in the inclined portion forming process are the inclination obtained by referring to a scanning electron microscope; SEM image of the part. The method for processing a sample according to item 4 of the scope of patent application, wherein: the sample is formed by overlapping a plurality of buried layers in the thickness direction inside the base material; in the slope forming process, The SEM image is used to count the number of the buried layers exposed in the inclined portion to determine a processing end point. The sample processing method according to any one of claims 3 to 5, wherein: in the inclined portion forming process, the thinned portion and a portion adjacent to the thinned portion The inclined portions are inclined to each other within a range of 10 ° or more and less than 90 °. The sample processing method according to any one of claims 3 to 6, wherein the sample processing method further includes an argon beam irradiation process in which the argon beam irradiation process is directed toward the micro test The sample piece is irradiated with an argon ion beam so as to be parallel to the inclined portion.