FIB sample holder for preparing horizontal grid platform and method of using the same

Abstract

The present invention relates to a FIB sample holder for preparing a horizontal grid platform and a method for using the same, wherein the FIB sample holder comprises a base and a grid clamping portion, the upper end of the base is provided with the grid clamping portion, and there is an angle between the grid clamping portion and the base; the grid clamping portion comprises a groove for placing the grid and a clip for clamping the grid. The present invention can improve the quality of TEM sample shooting and improve characterization efficiency.

Description

Technical Field

[0001] The present invention relates to the field of failure analysis in the semiconductor chip manufacturing industry, and in particular to a FIB sample holder for preparing a horizontal grid platform and a method for using the same. Background Art

[0002] Transmission Electron Microscopy (TEM) has nanometer-level resolution and is widely used in the field of semiconductor chip failure analysis. However, TEM has very high requirements for sample thickness (less than 100nm). Focused Ion Beam (FIB) is often used to prepare transmission electron microscope samples due to its high processing accuracy. With the continuous development and progress of semiconductor technology, the structure of devices is becoming more and more complex, and the traditional FIB cross-section sample preparation technology can no longer meet the needs of complex structure sample preparation.

[0003] Based on the FIB planar sample preparation technology, the target layer of the sample can be prepared for TEM. However, the existing FIB stage cannot be tilted at a large negative angle (less than 10°), that is, the ion beam cannot be perpendicular to the side of the semicircular grid. As a result, the plane of the cut semicircular grid has a slope, so that the TEM sample slice placed on it is not perpendicular to the semicircular grid platform. Angle compensation is required when shooting TEM samples, and too large an angle difference will cause the TEM characterization sample structure to be deformed. This greatly affects the quality of TEM sample shooting and makes the shooting steps more cumbersome. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a FIB sample holder for preparing a horizontal semicircular grid platform and a use method thereof, which can improve the quality of TEM sample shooting and improve the characterization efficiency.

[0005] The technical solution adopted by the present invention to solve its technical problem is: providing a FIB sample holder for preparing a horizontal grid platform, comprising a base and a grid clamping part, the grid clamping part is arranged on the upper end of the base, and there is an angle between the grid clamping part and the base; the grid clamping part comprises a groove for placing the grid and a clamping piece for clamping the grid.

[0006] The angle is 90-α, wherein α is the angle between the electron beam and the ion beam.

[0007] The base is 3-5 cm long, 0.4-1 cm wide and 1-2 cm high.

[0008] The number of the grooves is 2-6 and matches the size of the carrier grid.

[0009] The clip is a metal sheet with a length of 3-5 mm and a width of 1-3 mm.

[0010] The technical solution adopted by the present invention to solve the technical problem is: a method for using the above-mentioned FIB sample holder is also provided, comprising the following steps:

[0011] (1) placing the FIB sample holder holding the carrier grid in the FIB machine so that the angle between the carrier grid and the ion beam is 90°;

[0012] (2) adjusting the ion beam to a first parameter to vertically cut the grid;

[0013] (3) adjusting the ion beam to the second parameter, cutting the plane flat, and obtaining a horizontal grid-carrying platform;

[0014] (4) tilting the FIB sample holder 90° so that the electron beam is perpendicular to the horizontal grid platform;

[0015] (5) vertically moving the first needle with the sample attached to it to the vicinity of the horizontal grid platform, and opening the second needle with platinum gas passing therethrough;

[0016] (6) controlling the first needle to contact the horizontal grid platform, and then bonding the sample to the horizontal grid platform with platinum metal under the action of the electron beam and the second needle;

[0017] (7) cutting off the connection between the first needle and the sample, and retracting the first needle and the second needle;

[0018] (8) Rotate the sample stage 180°, and adhere the sample to the horizontal grid platform using steps (5) to (7) on the other side.

[0019] In the step (2), adjusting the ion beam to the first parameter specifically includes adjusting the acceleration voltage of the ion beam to 30 kV and the beam current to 9.3-20 nA.

[0020] In the step (2), adjusting the ion beam to the second parameter specifically includes adjusting the beam current of the ion beam to 2.5-9nA.

[0021] In the step (6), the acceleration voltage of the electron beam is 30 kV, and the beam current is 40 pA-90 pA.

[0022] Beneficial Effects

[0023] Due to the adoption of the above-mentioned technical scheme, the present invention has the following advantages and positive effects compared with the prior art: the present invention has a simple structure and is easy to operate. The sample can be placed on a horizontal semicircular grid plane cut by an ion beam, so that the final TEM sample slice is perpendicular to the semicircular grid plane, which simplifies the subsequent TEM characterization steps, overcomes the problem of deformed sample structure characterization caused by angle differences, and improves the TEM characterization quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of an embodiment of the present invention;

[0025] Figure 2 It is a schematic diagram of the principle of vertically cutting a semicircular grid plane in an embodiment of the present invention;

[0026] Figure 3 Schematic diagram of the effect of vertically cutting the semicircular grid plane in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0028] The embodiment of the present invention relates to a FIB sample holder for preparing a horizontal semicircular grid platform, such as Figure 1 As shown, it includes a base 1 and a semicircular mesh clamping portion 2. The semicircular mesh clamping portion 2 is provided on the upper end of the base 1 and is an integrated structure. There is an angle between the semicircular mesh clamping portion 2 and the base 1. In this embodiment, the angle is 38°; the semicircular mesh clamping portion 2 includes a groove 3 for placing the mesh and a clamping piece 4 for clamping the semicircular mesh.

[0029] The base is 3-5 cm long, 0.4-1 cm wide and 1-2 cm high, and can support the semicircular web-carrying clamping device. Preferably, in this embodiment, the base is 3 cm long, 1 cm wide and 1 cm high.

[0030] The semicircular web clamping device 2 has a semicircular groove 3 for placing the semicircular web. The groove 3 may have a diameter of 3-4 mm and is used to place the semicircular web. Preferably, the diameter of the groove 3 in this embodiment is 4 mm. The semicircular web clamping device 2 has a clamping piece 4 for clamping the semicircular web. In this embodiment, the clamping piece 4 is made of a stainless steel sheet metal. The sheet metal is 3-5 mm long and 1-3 mm wide. Preferably, the stainless steel sheet metal is 4 mm long and 2 mm wide in this embodiment.

[0031] The horizontal FIB semicircular grid platform preparation and sample adhesion process can be implemented using the above-mentioned FIB sample holder, which specifically includes the following steps:

[0032] Step 1: Place the semicircular grid in the semicircular groove of the FIB sample stage 3, adjust the metal sheet 4, and clamp the semicircular grid.

[0033] Step 2: Place the FIB sample stage holding the semicircular grid in step 1 in the FIB machine. At this time, the tilt angle of the sample stage is 0°.

[0034] Step 3: The angle between the semicircular grid and the ion beam is 90°, such as Figure 2 shown.

[0035] Step 4: Adjust the acceleration voltage of the ion beam to 30KV, the beam current to 20nA, vertically cut the semicircular grid, and set the cutting depth to 5 microns.

[0036] Step 5: Use an ion beam with a beam current of 9.3nA to cut the plane flat.

[0037] Step 6: The horizontal semicircular grid platform is now completed.

[0038] Step 7: Tilt the sample stage to 38°, so that the electron beam is perpendicular to the horizontal semicircular grid platform.

[0039] Step 8: Move the first needle with the sample attached vertically to the vicinity of the horizontal semicircular grid platform, and open the second needle with platinum gas passing through it.

[0040] Step 9: Control the first needle with the sample to contact the horizontal semicircular grid platform, and then use platinum metal to adhere the sample and the horizontal semicircular grid platform under the cooperation of the electron beam and the second needle. The acceleration voltage of the electron beam is 30KV, and the beam current is 60pA.

[0041] Step 10: Use a beam current of 2.5 nA to cut off the connection between the first needle and the sample, and retract the first needle and the second needle.

[0042] Step 11: Rotate the sample stage 180°, and use steps 8 to 10 on the other side to bond the joint between the sample and the horizontal semicircular grid platform with platinum metal.

[0043] Step 12: At this point, the adhesion process between the sample and the horizontal semicircular grid platform is completed. Figure 3 shown.

[0044] It is not difficult to find that the present invention has a simple structure and is easy to operate, and can place samples by cutting a horizontal semicircular grid plane using an ion beam, so that the final TEM sample slice is perpendicular to the semicircular grid plane, which simplifies the subsequent TEM characterization steps, overcomes the problem of sample structure characterization deformity caused by angle differences, and improves the TEM characterization quality.

Claims

1. A FIB sample holder for preparing a horizontal grid platform, characterized in that: It comprises a base and a grid clamping part, wherein the grid clamping part is arranged on the upper end of the base, and there is an angle between the grid clamping part and the base; the grid clamping part comprises a groove for placing the grid and a clamping piece for clamping the grid; the angle is 90-α, wherein α is the angle between the electron beam and the ion beam.

2. The FIB sample holder for preparing a horizontal grid platform according to claim 1, characterized in that: The base is 3-5 cm long, 0.4-1 cm wide and 1-2 cm high.

3. The FIB sample holder for preparing a horizontal grid platform according to claim 1, characterized in that: The number of the grooves is 2-6 and matches the size of the carrier grid.

4. The FIB sample holder for preparing a horizontal grid platform according to claim 1, characterized in that: The clip is a metal sheet with a length of 3-5 mm and a width of 1-3 mm.

5. A method for using a FIB sample holder for preparing a horizontal grid platform as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: (1) placing the FIB sample holder holding the carrier grid in the FIB machine so that the angle between the carrier grid and the ion beam is 90°; (2) adjusting the ion beam to a first parameter to vertically cut the grid; (3) adjusting the ion beam to the second parameter, cutting the plane flat, and obtaining a horizontal grid-carrying platform; (4) tilting the FIB sample holder 90° so that the electron beam is perpendicular to the horizontal grid platform; (5) vertically moving the first needle with the sample attached to it to the vicinity of the horizontal grid platform, and opening the second needle with platinum gas passing therethrough; (6) controlling the first needle to contact the horizontal grid platform, and then bonding the sample to the horizontal grid platform with platinum metal under the action of the electron beam and the second needle; (7) cutting off the connection between the first needle and the sample, and retracting the first needle and the second needle; (8) Rotate the sample stage 180°, and adhere the sample to the horizontal grid platform using steps (5) to (7) on the other side.

6. The method of use according to claim 5, characterized in that: In the step (2), adjusting the ion beam to the first parameter specifically includes adjusting the acceleration voltage of the ion beam to 30 kV and the beam current to 9.3-20 nA.

7. The method of use according to claim 5, characterized in that: In the step (2), adjusting the ion beam to the second parameter specifically includes adjusting the beam current of the ion beam to 2.5-9nA.

8. The method of use according to claim 5, characterized in that: In the step (6), the acceleration voltage of the electron beam is 30 kV, and the beam current is 40 pA-90 pA.

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