A method for preventing oxidation of TEM samples processed by FIB

Abstract

A method for preventing oxidation of TEM samples processed by FIB, comprising the following steps: 1) bonding the target sample to the sample stage and depositing a protective layer; 2) etching the target position in three directions; 3) welding the research area to a 3MM grid dedicated to TEM; 4) etching the front and back sides of the target sample; 5) depositing carbon on the front side of the aforementioned TEM sample; 6) depositing carbon on the back side of the sample. The advantages are: the present invention solves the problem that samples that are easily oxidized are difficult to characterize, and it is no longer necessary to rely on high-end instruments and equipment for characterization; it can be characterized in a regular photographic manner, without relying on high-end equipment for processing; it solves the problem of samples being oxidized by contact with air, and the deterioration of morphology and composition; after the FIB sample is prepared, the TEM sample is subjected to an anti-oxidation treatment, which can isolate the TEM sample from the air, thereby protecting the original structure of the sample; the present invention will not damage the structure of the sample itself, and solves the problem of active metals being easily oxidized.

Description

Technical Field

[0001] The invention belongs to the technical field of material analysis, and in particular relates to an anti-oxidation treatment method for FIB processed TEM samples. Background Art

[0002] The use of focused ion beam (FIB) sample preparation is the most important TEM sample preparation method in the field of metal materials. The research sample is subsequently thinned to a thickness of 50nm to provide high-quality samples for subsequent TEM photography. Transmission electron microscopy is a very important analytical tool in materials science research. It can perform morphological analysis, structural analysis and composition analysis of samples, and produce high-resolution images; element distribution; electron diffraction. It has extremely wide and increasingly important applications in the fields of materials science and integrated circuit analysis. Since the emergence of easily oxidized samples, the existing technology can only be replaced with TEM equipment immediately after the dual-beam equipment is processed; or the most advanced equipment is used for processing, and the sample is in a vacuum state from beginning to end to meet the test requirements; conventional sample preparation, the sample will inevitably come into contact with air during the transfer process, so it can only be characterized by relying on more advanced instruments and equipment. This undoubtedly increases costs and reduces work efficiency. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for preventing oxidation of TEM samples processed by FIB.

[0004] The technical solution adopted by the present invention to solve the technical problem is: a method for preventing oxidation of TEM samples processed by FIB, characterized in that it includes the following steps: 1) Glue the target sample to the sample stage of the focused ion beam system, select the target position of the area to be studied according to the electron beam imaging, and deposit the protective layer; 2) Etching the target position: Separate the target position from the substrate and retain the protective layer; according to the depth requirements of the viewing area, etch grooves above and below the protective layer to complete the pre-processing; 3) The original sample under the protective layer in the studied area is taken out by a robot and welded to the FIB grid; the target sample is obtained and waits for the next processing; 4) Use FIB to etch the front and back surfaces of the target sample until the thickness of the target sample is 50nm±5nm, completing the TEM sample processing; 5) Adjust the angle of the sample stage of the processed TEM sample in the focused ion beam device, fully expose the front of the sample to the electron beam, click the gas needle (carbon) equipped with the focused ion beam device, and insert the gas needle (carbon); the gas needle tip is 1-300μm away from the sample, set the working pattern size according to the shooting position size, and place the sample area to be studied in the center of the working pattern; perform carbon deposition on the front of the sample area to be studied, and calibrate the thickness of the deposited carbon to 1nm-150nm, and wait for the focused ion beam device to complete work; 6) Adjust the angle of the sample stage, expose the back of the sample to the electron beam, insert the gas needle equipped with the focused ion beam device, and place the gas needle tip 1-300μm away from the sample; set the working pattern size according to the shooting position size, place the area to be analyzed in the center of the working pattern, perform carbon deposition on the back of the sample area, and calibrate the thickness to 1nm-150nm. Wait for the focused ion beam device to complete the work, that is, complete all the anti-oxidation processing; TEM analysis and shooting can be carried out directly afterwards.

[0005] Preferably, in step 1), the focused ion beam device may be a focused ion beam / electron beam dual beam device.

[0006] Preferably, in step 2), the target position is etched: the target position and the substrate are separated, and the protective layer is retained; according to the depth requirements of the viewing area, grooves are etched above and below the protective layer, as well as on the left or right side to complete the pre-processing.

[0007] Compared with the prior art, the present invention has the following beneficial effects: the present invention can solve the problem that samples of active metals that are easily oxidized are difficult to characterize, without having to rely on high-end instruments and equipment for characterization; the present invention can be characterized by conventional photographing methods, without having to rely on high-end equipment for processing; the present invention solves the problem that samples are oxidized when exposed to air, and their morphology and composition are deteriorated; after the FIB sample preparation is completed, the present invention performs an anti-oxidation treatment on the TEM sample, which can isolate the TEM sample from the air, thereby protecting the original structure of the sample; the anti-oxidation treatment method of the present invention will not damage the structure of the sample itself, and solves the problem that active metals are easily oxidized. DETAILED DESCRIPTION

[0008] The present invention will be further described below in conjunction with embodiments: Example 1

[0009] A method for preventing oxidation of a FIB processed TEM sample comprises the following steps: 1) Glue the target sample to the sample stage of the focused ion beam device, select the target position of the area to be studied according to the electron beam imaging, and deposit the protective layer; 2) Etch the target position in two directions: separate the target position from the substrate and retain the protective layer; etch 15*15μm grooves above and below the protective layer to complete the pre-processing; 3) The original sample under the protective layer in the studied area is taken out by a robot and welded to a 3 mm grid dedicated to TEM; the target sample is obtained and waits for the next processing; 4) Use FIB (focused ion beam) to etch the front and back sides of the target sample until the thickness of the target sample is less than 50nm to complete the TEM sample processing; 5) For the processed TEM sample, adjust the sample stage to 0 degrees in the dual-beam device, fully expose the front of the sample to the electron beam, click the carbon gas needle equipped with the dual-beam device, and insert the gas needle; the tip of the gas needle is 1μm-150μm away from the sample, set the working pattern (processing pattern) size to x=5μm, y=5μm, z=0.01μm, place the sample area to be studied in the center of the working pattern, perform carbon deposition on the front of the sample area to be studied, and calibrate the thickness of the deposited carbon to 100nm, and wait for the dual-beam device to complete the work; 6) Expose the back of the sample to the electron beam, adjust the angle of the sample stage to 59 degrees, and insert the probe equipped with the dual-beam equipment; insert the probe; the probe tip is 150μm away from the sample; set the working pattern (processing graphic) size to x=5μm, y=5μm, z=0.01μm, place the area to be analyzed in the center of the working pattern, perform carbon deposition on the back of the sample area, and calibrate the thickness to 100nm. Wait for the dual-beam equipment to complete the work, that is, complete all the anti-oxidation processing; TEM analysis and shooting can be carried out directly afterwards. Example 2

[0010] A method for preventing oxidation of a FIB processed TEM sample comprises the following steps: 1) Glue the target sample to the sample stage of the focused ion beam / electron beam dual beam device, select the target position of the area to be studied according to the electron beam imaging, and deposit the protective layer; 2) Etch the target position in three directions: separate the target position from the substrate and retain the protective layer; etch 15*15μm grooves above and below the protective layer, and etch 8*8μm grooves on the left side to complete the pre-processing; 3) The original sample under the protective layer in the studied area is taken out by a robot and welded to the FIB grid; the target sample is obtained and waits for the next processing; 4) Use FIB (focused ion beam) to etch the front and back sides of the target sample until the TEM sample processing is completed when the thickness of the target sample is 55nm; 5) For the processed TEM sample, adjust the sample stage to 0 degrees in the dual-beam device, fully expose the front of the sample to the electron beam, click the probe equipped with the dual-beam device, and insert the probe; the probe tip is 200μm away from the sample, set the working pattern size to x=15μm, y=15μm, z=0.02μm, place the sample area to be studied in the center of the working pattern, perform carbon deposition on the front of the sample area to be studied, and calibrate the thickness of the deposited carbon to 100nm, and wait for the dual-beam device to complete the work; 6) Expose the back of the sample to the electron beam, adjust the angle of the sample stage to 59 degrees, and insert the carbon gas needle equipped with the dual-beam equipment; insert the gas needle; the tip of the gas needle is 1μm-200μm away from the sample; set the working pattern size to x=15μm, y=15μm, z=0.05μm, place the area to be analyzed in the center of the working pattern, and perform carbon deposition on the back of the sample area with a thickness calibration of 50nm. Wait for the dual-beam equipment to complete the work, that is, complete all the anti-oxidation processing; TEM analysis and shooting can be carried out directly afterwards. Example 3

[0011] A method for preventing oxidation of a FIB processed TEM sample comprises the following steps: 1) Glue the target sample to the sample stage of the focused ion beam / electron beam dual beam device, select the target position of the area to be studied according to the electron beam imaging, and deposit the protective layer; 2) Etch the target position in three directions: separate the target position from the substrate and retain the protective layer; etch 20*20μm grooves above and below the protective layer, and etch 12*12μm grooves on the left side to complete the pre-processing; 3) The original sample under the protective layer in the studied area is taken out by a robot and welded to the FIB grid; the target sample is obtained and waits for the next processing; 4) Use FIB (focused ion beam) to etch the front and back sides of the target sample until the TEM sample processing is completed when the thickness of the target sample is 45nm; 5) For the processed TEM sample, adjust the sample stage to 0 degrees in the dual-beam device, fully expose the front of the sample to the electron beam, click the carbon gas needle equipped with the dual-beam device, insert the gas needle, and position the gas needle tip 1μm to 200μm away from the sample. Set the working pattern size to x=15μm, y=15μm, z=0.05μm, place the sample area to be studied in the center of the working pattern, perform carbon deposition on the front of the sample area to be studied, and calibrate the thickness of the deposited carbon to 50nm, and wait for the dual-beam device to complete the work; 6) Expose the back of the sample to the electron beam, adjust the angle of the sample stage to 59 degrees, and insert the probe equipped with the dual-beam equipment; insert the probe; the probe tip is 200μm away from the sample; set the working pattern (processing graphic) size to x=15μm, y=15μm, z=0.05μm, place the area to be analyzed in the center of the working pattern, perform carbon deposition on the back of the sample area, and calibrate the thickness to 50nm. Wait for the dual-beam equipment to complete the work, that is, complete all the anti-oxidation processing; TEM analysis and shooting can be carried out directly afterwards.

[0012] Since the FIB deposited carbon protective layer has no contrast in TEM (transmission electron microscope) imaging, the covering carbon film is a few to a dozen nanometers thick; in addition, the additional carbon component of the carbon film has a very limited effect on the imaging signal of the TEM (transmission electron microscope) equipment; therefore, the contrast effect of this type of very thin carbon film on TEM imaging can be ignored and does not affect the structure and composition of the original material.

[0013] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A method for preventing oxidation of TEM samples processed by FIB, characterized in that: The steps include: 1) Glue the target sample to the sample stage of the focused ion beam system, select the target position of the area to be studied according to the electron beam imaging, and deposit the protective layer; 2) Etching the target position: separating the target position from the substrate and retaining the protective layer; According to the depth requirements of the viewing area, grooves are etched above and below the protective layer to complete the pre-processing; 3) The original sample under the protective layer in the studied area is taken out by a robot and welded to the FIB grid; Get the target sample and wait for the next step of processing; 4) Use FIB to etch the front and back surfaces of the target sample until the thickness of the target sample is 50nm±5nm, completing the TEM sample processing; 5) Adjust the angle of the sample stage of the processed TEM sample in the focused ion beam device, fully expose the front of the sample to the electron beam, click the gas needle (carbon) equipped with the focused ion beam device, and insert the gas needle (carbon); the gas needle tip is 1-300μm away from the sample, set the working pattern size according to the shooting position size, and place the sample area to be studied in the center of the working pattern; perform carbon deposition on the front of the sample area to be studied, and calibrate the thickness of the deposited carbon to 1nm-150nm, and wait for the focused ion beam device to complete work; 6) Adjust the angle of the sample stage, expose the back of the sample to the electron beam, insert the gas needle equipped with the focused ion beam device, and place the gas needle tip 1-300μm away from the sample; set the working pattern size according to the shooting position size, place the area to be analyzed in the center of the working pattern, perform carbon deposition on the back of the sample area, and calibrate the thickness to 1nm-150nm. Wait for the focused ion beam device to complete the work, that is, complete all the anti-oxidation processing; TEM analysis and shooting can be carried out directly afterwards.

2. The method for preventing oxidation of TEM samples processed by FIB according to claim 1, characterized in that: In step 1), the focused ion beam device may be a focused ion beam / electron beam dual beam device.

3. The method for preventing oxidation of TEM samples processed by FIB according to claim 2, characterized in that: Step 2) Etch the target position: separate the target position from the substrate and retain the protective layer; according to the depth requirements of the viewing area, etch grooves above and below the protective layer, as well as on the left or right side to complete the pre-processing.