Apparatus and method for eliminating thinning error angle for fast FIB lift-out TEM sample

Abstract

This invention relates to the field of transmission electron microscopy (TEM) sample fabrication technology, and discloses a device and method for rapidly eliminating thinning error angles during FIB inverted cutting of TEM samples. The device includes: a stage with a first mounting groove on its upper surface for fixing a semiconductor workpiece; a mesh holder with a second mounting groove on its upper surface for fixing a lift-out mesh; when the lift-out mesh is fixed in the second mounting groove, the toothed column of the lift-out mesh is located at the upper end; a nanomechanical needle for extracting a thin sheet sample formed on the semiconductor workpiece, the thin sheet sample including a substrate and a surface layer on the substrate; and a transfer device that, when the thin sheet sample is connected to the transfer device, can rotate the thin sheet sample 180° longitudinally. This invention eliminates the need for rotating the electron microscope, rotating the nanomechanical arm, and vertically tilting the lift-out mesh, thus eliminating the angle difference generated during FIB inverted cutting and ensuring that the ion beam is completely parallel to the top surface of the thin sheet sample during FIB inverted cutting, without needing to calibrate the actual platform tilt angle of the ion beam parallel to the sample structure.

Description

Technical Field

[0001] This invention relates to the field of transmission electron microscopy sample fabrication technology, and in particular to an apparatus and method for rapidly inverting TEM samples using FIB to eliminate thinning error angles. Background Technology

[0002] Focused ion beam (FIB) back-cutting is a fabrication technique for preparing high-quality transmission electron microscope (TEM) samples. The fabrication steps are as follows: 1. Pre-process the sample and rotate the platform counterclockwise by 90°; 2. Extract the sample using a nanorobot and rotate it 180°, then weld it to a flat-lying lift-out grid; 3. Transfer the grid out of the microscope chamber and place it vertically for final back-cutting and thinning. Due to the multiple rotation operations of the platform, nanorobot, and grid, the chip structure (such as silicon fins or polycrystalline gates) is not parallel to the electron beam (SEM) after the sample is re-transferred out of the microscope chamber, resulting in an angular difference. Therefore, it is necessary to side-cut the sample and detect the error angle between the chip structure and the ion beam processing at the standard vertical ion beam tube tilt angle. When the sum of the error angle and the vertical ion beam tilt angle exceeds the limiting tilt angle of the dual-beam electron microscope platform, the electron microscope will be unable to observe and process one side of the sample in real time, leading to FIB back-cutting failure.

[0003] Therefore, how to provide a FIB back-cutting method that can avoid generating angle differences is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide an apparatus and method for rapidly eliminating thinning error angles in FIB inverted cutting of TEM samples, so as to solve the problems existing in the prior art.

[0005] To achieve the above objectives, the present invention provides an apparatus for rapidly eliminating thinning error angles in FIB inverted TEM samples, comprising: A mechanical table, mounted on a dual-axis moving platform, is capable of moving laterally, and the upper surface of the mechanical table is provided with multiple mounting holes; A nailing station, the upper surface of which has a first mounting groove for fixing a semiconductor workpiece; A net carrier clamp has a second mounting groove on its upper surface for fixing the Lift-out net carrier; when the Lift-out net carrier is fixed in the second mounting groove, the toothed post of the Lift-out net carrier is located at the upper end; the nail platform and the net carrier clamp are respectively set in different mounting holes; Nanomechanical needles are used to extract thin sheet samples formed on semiconductor workpieces, the thin sheet samples comprising a substrate and a surface layer located on the substrate; A transfer device is provided, which allows the thin-film sample to be connected to and disconnected from the transfer device. When the thin-film sample is connected to the transfer device, the transfer device can rotate the thin-film sample 180° longitudinally.

[0006] Furthermore, the transfer device includes: The U-shaped component has an opening facing upwards, and its bottom surface is fixed to the upper surface of the machine table or fixed to the mounting hole by means of a nail leg. A tungsten needle is detachably mounted on one end of a bushing, the bushing being rotatably mounted on the two side plates of the U-shaped part, and a groove cap is provided on the other end of the bushing, with a slot formed on the groove cap; A spring set screw is provided on the side plate of the U-shaped part, which allows the thin sample to be connected to and disconnected from the tungsten needle. A limiting groove is provided on the bushing. When the thin sample is connected to the tungsten needle, the bushing, tungsten needle and thin sample are rotated 180° longitudinally, at which time the spring set screw is pushed into the limiting groove.

[0007] Furthermore, the tungsten needle has a diameter of 0.5 mm and a tip diameter of <2 μm, and the thin film sample is deposited onto the tip of the tungsten needle via gas injection.

[0008] Furthermore, the nanomechanical needles are attached to the sheet sample via gas injection deposition.

[0009] This invention provides a method for rapidly eliminating thinning error angles by inverting TEM samples using FIB (Fiber Optic Injection) and an apparatus for doing so, comprising the following steps: S1: Fix the semiconductor workpiece on the nail stage, move the mechanical stage to move the semiconductor workpiece to the confocal working position of the ion beam tube and the electron beam tube, and deposit a protective layer on the semiconductor workpiece by gas injection to form a thin film sample. The protective layer is located on the surface layer of the thin film sample. S2: Extract a thin-film sample at a location of interest on a semiconductor workpiece using a nanomechanical needle. During extraction, the nanomechanical needle is connected to the protective layer deposited on the thin-film sample via gas injection deposition, forming a first connection point. The mechanical stage is moved to the confocal working position of the ion beam and electron beam microscope tubes. The substrate of the thin-film sample is connected to the tip of the tungsten needle via gas injection deposition, forming a second connection point. The first connection point is then severed, and the nanomechanical needle is withdrawn. S3: Move the mechanical stage to move the tungsten needle to the preset position, and rotate the shaft sleeve through the groove cap to make the tungsten needle and the thin sample rotate 180° longitudinally. At this time, the spring set screw is inserted into the limiting groove. S4: The moving mechanical stage moves the thin-film sample to the confocal working position of the ion beam tube and the electron beam tube. The nanomechanical needle enters and connects the substrate of the thin-film sample to the nanomechanical needle through gas injection deposition. A third connection point is formed at the connection point. The second connection point is cut off, and the nanomechanical arm carries the thin-film sample out. S5: Move the mechanical stage to the confocal working position of the ion beam and electron beam tubes. Use a nanorobot to move the sheet sample to the side of the toothed column of the Lift-out mesh. Use gas injection deposition to attach the sheet sample to the side of the toothed column of the Lift-out mesh and cut the third connection point to start the FIB back-cutting.

[0010] Furthermore, in step S3, the slot cap is rotated by inserting a screwdriver into the slot.

[0011] The present invention discloses the following technical effects: This invention proposes a novel FIB inverting method for eliminating thinning error angles in TEM samples based on a rapid FIB inverting technique. This method eliminates the need for rotating the electron microscope, rotating the nanorobot, or vertically tilting the lift-out support, thus eliminating the angle difference generated during the FIB inverting process. It ensures that the ion beam is completely parallel to the top surface of the thin-film sample during FIB inverting, without the need to calibrate the actual platform tilt angle of the ion beam parallel to the sample structure. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 A schematic diagram of nanomechanical needles extracting thin-film samples; Figure 2 A schematic diagram showing the tungsten needle moving to the confocal working position of the ion beam tube and the electron beam tube; Figure 3 This is a schematic diagram showing the connection between a nanomechanical needle and a thin-film sample. Figure 4 This is a schematic diagram showing the connection between the tungsten needle and the thin-film sample; Figure 5 A schematic diagram of a rotating tungsten needle; Figure 6 A schematic diagram showing the tungsten needle moving again to the confocal working position of the ion beam tube and the electron beam tube; Figure 7 This is a schematic diagram of the rotated tungsten needle and the thin-film sample. Figure 8 Schematic diagrams showing the disconnection of the tungsten needle from the thin-film sample and the reconnection of the nanomechanical needle to the thin-film sample; Figure 9 A schematic diagram showing the movement of a thin-film sample to a lift-out grid. Figure 10 A schematic diagram showing the connection between the thin-film sample and the toothed post of the Lift-out carrier mesh; Among them, 1. Semiconductor workpiece; 2. Ion beam microscope tube; 3. Electron beam microscope tube; 4. Nanomechanical needle; 5. Thin sheet sample; 6. U-shaped part; 7. Lift-out carrier; 8. Mechanical stage; 9. Tungsten needle; 10. First connection point; 11. Deposited protective layer; 12. Second connection point; 13. Electron microscope vacuum chamber flange plate; 14. Screwdriver; 15. Spring set screw; 16. Groove cap; 17. Third connection point; 18. Tooth column. Detailed Implementation

[0014] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] Those skilled in the art will understand that the term "comprising" as used in this application means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements present. Furthermore, "connected" or "coupled" as used herein can include wireless connections or wireless coupling. The term "and / or" as used herein includes all or any unit and all combinations of one or more associated listed items.

[0016] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] like Figures 1 to 10 This invention provides an apparatus for rapidly eliminating thinning error angles in FIB inverted TEM samples, comprising: The mechanical table 8 is set on a dual-axis moving platform and can move laterally. The upper surface of the mechanical table 8 is provided with multiple mounting holes. The nailing station has a first mounting groove on its upper surface for fixing the semiconductor workpiece 1. The mesh holder has a second mounting groove on its upper surface for fixing the Lift-out mesh 7 (a special electron microscope mesh for supporting tiny sample sections); when the Lift-out mesh 7 is fixed in the second mounting groove, the toothed post 18 of the Lift-out mesh 7 is located at the upper end; the nail stage and the mesh holder are respectively set in different mounting holes; Nanomechanical needle 4 is used to extract a thin sheet sample 5 formed on a semiconductor workpiece 1. The thin sheet sample 5 includes a substrate and a surface layer located on the substrate. The transfer device allows the thin film sample 5 to be connected to and disconnected from the transfer device. When the thin film sample 5 is connected to the transfer device, the transfer device can rotate the thin film sample 5 180° longitudinally.

[0018] In this embodiment, the transfer device includes: U-shaped part 6, with its opening facing upward, has its bottom surface fixed to the upper surface of the machine table 8 or fixed to the mounting hole by means of nail legs; the transfer device, nail table, and net clamp are respectively set in different mounting holes; Tungsten needle 9 is detachably mounted on one end of the bushing sleeve, the bushing sleeve is rotatably mounted on the two side plates of the U-shaped part 6, and the other end of the bushing sleeve is provided with a groove cap 16, on which a slot is formed. Spring set screw 15 is set on the side plate of U-shaped part 6. Thin sheet sample 5 can be connected to tungsten needle 9 and disconnected from tungsten needle 9. A limiting groove is opened on the bushing. When thin sheet sample 5 is connected to tungsten needle 9, the bushing, tungsten needle 9 and thin sheet sample 5 are rotated 180° longitudinally. At this time, spring set screw 15 is pushed into the limiting groove.

[0019] In this embodiment, the tungsten needle 9 has a diameter of 0.5 mm and a tip diameter of <2 μm. The thin-film sample 5 is deposited onto the tip of the tungsten needle 9 via gas injection, enabling good connection and cutting with the thin-film sample 5. The tungsten needle 9 is detachably connected to the bushing, such as by snap-fit, and the height difference between the tip of the tungsten needle 9 and the highest point of the bushing does not exceed 4 mm.

[0020] In this embodiment, the nanomechanical needle 4 is attached to the sheet sample 5 by gas injection deposition.

[0021] This invention provides a method for rapidly eliminating thinning error angles by inverting TEM samples using FIB (Fiber Optic Injection) and an apparatus for doing so, comprising the following steps: S1: Fix the semiconductor workpiece 1 on the nail stage, move the mechanical stage 8 to the confocal working position of the ion beam tube 2 and the electron beam tube 3, and form a protective deposition layer 11 on the semiconductor workpiece 1 by gas injection deposition. A thin film sample 5 is then formed on the semiconductor workpiece 1. The protective deposition layer 11 is located on the surface layer of the thin film sample 5. The specific processing method of the thin film sample 5 adopts existing TEM sample preparation methods, which will not be elaborated here. It should be noted that gas injection deposition, also known as focused ion beam induced deposition, uses a gas precursor (W, Pt, etc.) as raw material. The precursor gas molecules injected through the gas needle are decomposed by selective target area irradiation with an ion beam. The volatile portion of the gas is removed by the electron microscope vacuum system, and the unvolatile particles are deposited in the selective target area, thereby forming the protective deposition layer 11 or a connecting function. Regarding the semiconductor workpiece 1, its structural composition is largely the same as that of the fabricated thin film sample 5, also including a substrate and a surface layer. S2: Extract the thin film sample 5 at the sample location of interest on the semiconductor workpiece 1 using the nanomechanical needle 4. During extraction, the nanomechanical needle 4 is connected to the deposition protective layer 11 on the thin film sample 5 by gas injection deposition, forming a first connection point 10 at the connection point. Move the mechanical stage 8 to move the tungsten needle 9 to the confocal working position of the ion beam tube 2 and the electron beam tube 3. Connect the substrate of the thin film sample 5 to the tip of the tungsten needle 9 by gas injection deposition, forming a second connection point 12 at the connection point. Cut off the first connection point 10 and withdraw the nanomechanical needle 4. S3: Move the mechanical stage 8 to move the tungsten needle 9 to the preset position, and rotate the shaft sleeve through the groove cap 16 to make the tungsten needle 9 and the thin sample 5 rotate 180° longitudinally. At this time, the spring set screw 15 is pushed into the limiting groove. S4: The moving mechanical stage 8 moves the thin film sample 5 to the confocal working position of the ion beam tube 2 and the electron beam tube 3. The nanomechanical needle 4 enters and connects the substrate of the thin film sample 5 with the nanomechanical needle 4 through gas injection deposition. A third connection point 17 is formed at the connection point. The second connection point 12 is cut off, and the nanomechanical arm carries the thin film sample 5 out. S5: Move the mechanical stage 8 to move the Lift-out carrier 7 to the confocal working position of the ion beam tube 2 and electron beam tube 3. Use a nano-manipulator to move the sheet sample 5 to the side of the toothed post 18 of the Lift-out carrier 7. Use gas injection deposition to connect the sheet sample 5 to the side of the toothed post 18 of the Lift-out carrier 7 and cut the third connection point 17 to start the FIB back-cutting.

[0022] In this embodiment, in step S3, the screwdriver 14 is inserted into the slot and the slot cap 16 is rotated. Specifically, the screwdriver 14 is of the slot type and is inserted from the flange opening of the electron microscope vacuum chamber flange plate 13.

[0023] In this embodiment, all structures are made of non-magnetic materials such as austenitic stainless steel, copper, aluminum, titanium, and tungsten, which will not affect the optical path of the electron microscope.

[0024] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0026] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A device for rapidly eliminating thinning error angles in FIB inverted cutting of TEM samples, characterized in that, include: The mechanical table (8) is set on a dual-axis moving platform and can move laterally. The upper surface of the mechanical table (8) is provided with multiple mounting holes. A nailing station, the upper surface of which has a first mounting groove for fixing a semiconductor workpiece (1); The net carrier clamp has a second mounting groove on its upper surface for fixing the Lift-out net carrier (7); when the Lift-out net carrier (7) is fixed in the second mounting groove, the toothed post (18) of the Lift-out net carrier (7) is located at the upper end; the nail station and the net carrier clamp are respectively set in different mounting holes; Nanomechanical needles (4) are used to extract thin sheet samples (5) formed on semiconductor workpieces (1), the thin sheet samples (5) including a substrate and a surface layer located on the substrate; The transfer device is capable of connecting to and disconnecting the thin sheet sample (5) from the transfer device. When the thin sheet sample (5) is connected to the transfer device, the transfer device is capable of rotating the thin sheet sample (5) 180° longitudinally. The transfer device includes: U-shaped part (6), the opening direction of the U-shaped part (6) is upward, and its bottom surface is fixed to the upper surface of the machine table (8) or fixed to the mounting hole by the nail leg; A tungsten needle (9) is detachably mounted on one end of a bushing. The bushing is rotatably mounted on the two side plates of the U-shaped part (6). A groove cap (16) is provided on the other end of the bushing. A slot is formed on the groove cap (16). A spring set screw (15) is provided on the side plate of the U-shaped part (6). The thin sample (5) can be connected to the tungsten needle (9) and disconnected from the tungsten needle (9). A limiting groove is provided on the bushing. When the thin sample (5) is connected to the tungsten needle (9), the bushing, the tungsten needle (9) and the thin sample (5) are rotated 180° longitudinally. At this time, the spring set screw (15) is pushed into the limiting groove.

2. The apparatus for rapidly eliminating thinning error angles in FIB inverted TEM sample cutting according to claim 1, characterized in that, The tungsten needle (9) has a diameter of 0.5 mm and a tip diameter of <2 μm. The sheet sample (5) is deposited onto the tip of the tungsten needle (9) by gas injection.

3. The apparatus for rapidly eliminating thinning error angles in FIB inverted TEM sample cutting according to claim 2, characterized in that, The nanomechanical needle (4) is attached to the sheet sample (5) by gas injection deposition.

4. A method for rapidly eliminating thinning error angles in FIB inverted cutting of TEM samples, characterized in that, The apparatus for rapidly eliminating thinning error angles by inverting TEM samples using FIB as described in claim 3 includes the following steps: S1: Fix the semiconductor workpiece (1) on the nail stage, move the mechanical stage (8), move the semiconductor workpiece (1) to the confocal working position of the ion beam tube (2) and the electron beam tube (3), deposit a protective layer (11) on the semiconductor workpiece (1) by gas injection, and process a thin film sample (5) on the semiconductor workpiece (1). The protective layer (11) is located on the surface layer of the thin film sample (5). S2: Extract the thin film sample (5) at the sample location of interest on the semiconductor workpiece (1) using a nanomechanical needle (4). During extraction, the nanomechanical needle (4) is connected to the deposition protective layer (11) on the thin film sample (5) by gas injection deposition, and a first connection point (10) is formed at the connection point. Move the mechanical stage (8) to move the tungsten needle (9) to the confocal working position of the ion beam tube (2) and the electron beam tube (3). Connect the substrate of the thin film sample (5) to the tip of the tungsten needle (9) by gas injection deposition, and a second connection point (12) is formed at the connection point. Cut off the first connection point (10) and remove the nanomechanical needle (4). S3: Move the mechanical stage (8) to move the tungsten needle (9) to the preset position, and rotate the bushing through the groove cap (16) to make the tungsten needle (9) and the thin sample (5) rotate 180° in the longitudinal direction. At this time, the spring set screw (15) is pushed into the limiting groove. S4: Move the mechanical stage (8) to move the thin film sample (5) to the confocal working position of the ion beam tube (2) and the electron beam tube (3). The nanomechanical needle (4) enters and connects the substrate of the thin film sample (5) to the nanomechanical needle (4) through gas injection deposition. A third connection point (17) is formed at the connection point. The second connection point (12) is cut off, and the nanomechanical arm carries the thin film sample (5) out. S5: Move the mechanical stage (8) to move the Lift-out mesh (7) to the confocal working position of the ion beam tube (2) and electron beam tube (3), move the sheet sample (5) to the side of the toothed post (18) of the Lift-out mesh (7) by the nanomanipulator, connect the sheet sample (5) to the side of the toothed post (18) of the Lift-out mesh (7) by gas injection deposition and cut off the third connection point (17), and start the FIB back cutting.

5. The method for eliminating thinning error angle by rapidly inverting a TEM sample using FIB as described in claim 4, characterized in that, In step S3, the screwdriver (14) is inserted into the slot and the slot cap (16) is rotated.

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