Sample welding method and sample preparation method
By depositing byproducts generated by ion etching at the contact point between the sample and the sample stage, the problem of weak sample welding is solved, high-strength connection is achieved, and costs are reduced.
Patent Information
- Application Number
- CN202411116719.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-14
- Publication Date
- 2026-03-03
AI Technical Summary
In existing technologies, the welding between the sample and the copper sheet is not strong, which makes the sample easy to fall off. In addition, the use of high-cost welding materials such as tungsten or platinum increases the welding cost.
Ion etching is used to etch the area near the contact point between the sample and the sample stage. The byproducts generated by ion etching are deposited at the contact point to fix the sample to the sample stage, thus avoiding the use of high-cost tungsten or platinum materials.
It improves the connection strength between the sample and the sample stage, reduces the risk of sample detachment, and reduces the cost of welding materials.
Smart Images
Figure CN121595602A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor manufacturing technology, and in particular to a sample welding method and a sample preparation method. Background Technology
[0002] In the semiconductor process development process, each process station requires transmission electron microscopy (TEM) to analyze the sample in order to obtain the relationship between parameters such as the uniformity of the thickness of the process structure in processes such as metal trench etching and metal sputtering, and the key dimensions of the metal trench, thereby helping the process department to improve chip performance.
[0003] TEM characterization requires sample preparation using focused ion beam (FIB). During sample preparation, the desired sample location must be extracted and welded onto a copper sheet. This is typically done using the instrument's built-in gas injection system (GIS) to weld the sample to the copper sheet using tungsten (W) or platinum (Pt). The sample is then thinned using FIB. The tungsten or platinum welding materials used in this process are relatively expensive. Furthermore, for some samples, in addition to observing their surface (plan-view) using TEM, it is also necessary to observe their cross-section. During this process, the sample after surface observation needs to be transferred to the FIB instrument for further processing. If the welding is not secure, the sample may fall off the copper sheet, affecting the observation of the sample.
[0004] Therefore, it is necessary to develop a sample welding method that ensures the strong weld between the sample and the copper sheet while reducing material costs during the welding process. Summary of the Invention
[0005] The purpose of this application is to provide a sample welding method that ensures the strong weld between the sample and the sample stage while reducing the material cost during the welding process.
[0006] In a first aspect, this application provides a sample welding method, comprising: providing a sample stage, the sample stage including at least one recess; placing the sample on top of at least one of the recesses, the sample having at least one contact point with a side of the recess; and using ion etching to etch a region near the contact point so that byproducts sputtered during the ion etching process are at least partially deposited at the contact point and the sample is fixedly connected to the side of the recess.
[0007] In some embodiments, the ion etching method is focused ion beam etching.
[0008] In some embodiments, the focused ion beam etching is performed using the graphic mode of a focused ion beam machine.
[0009] In some embodiments, the current of the focused ion beam etching is 0.9 to 1.1 nA; the voltage of the focused ion beam etching is 25 to 35 kV; and the duration of the focused ion beam etching is 30 to 40 s.
[0010] In some embodiments, the ion source used for the focused ion beam etching is a Ga gallium ion source.
[0011] In some embodiments, the distance between the etched area and the contact point is 1 to 2 μm.
[0012] In some embodiments, the sample has four contact points with the side of the recess; and the number of etched areas is two.
[0013] In some embodiments, the sample stage includes a plurality of columns, each of which has a recess on its top surface.
[0014] In some embodiments, the sample stage is made of copper.
[0015] Secondly, this application also provides a sample preparation method, comprising: cutting a sample to expose the cross section of the sample to be observed; welding the sample to a sample stage using the sample welding method described in the first aspect of this application; and thinning the sample to a set thickness.
[0016] The beneficial effects of the sample welding method provided in this application include, but are not limited to, the following:
[0017] This application uses ion etching to fix the contact point between the sample and the side of the sample stage recess to the side of the recess using the byproducts sputtered during the ion etching process. During the process, the sample stage is the object of ion etching, and there is no need to provide additional high-cost welding materials such as tungsten or platinum, thus reducing the cost of sample welding.
[0018] Furthermore, the sample welding method provided in this application can achieve fixed connection of all contact points between the sample and the side of the sample stage recess through the side of the recess by sputtering, thereby improving the connection strength between the sample and the sample stage and reducing the sample drop rate from the sample stage. Attached Figure Description
[0019] The following accompanying drawings describe in detail the exemplary embodiments disclosed in this application. The same reference numerals denote similar structures in several views of the drawings. Those skilled in the art will understand that these embodiments are non-limiting and exemplary, and the drawings are for illustrative purposes only and are not intended to limit the scope of this application. Other embodiments may similarly fulfill the inventive intent of this application. It should be understood that the drawings are not drawn to scale.
[0020] in:
[0021] Figure 1 This is a schematic diagram illustrating the welding of a sample using existing sample welding methods.
[0022] Figure 2 for Figure 1 The sample stage is shown as a top view after the sample has been welded using the welding method shown.
[0023] Figure 3 This is a flowchart of a sample welding method according to some embodiments of this application;
[0024] Figure 4 This is a schematic diagram of a sample stage structure in which the etched area according to some embodiments of this application has not undergone ion etching;
[0025] Figure 5 This is a schematic diagram of the sample stage after welding according to some embodiments of this application;
[0026] Figure 6 for Figure 5 A top view of the sample stage shown; and
[0027] Figure 7 This is a schematic diagram of the structure of a sample stage according to some embodiments of this application. Detailed Implementation
[0028] The following description provides specific application scenarios and requirements for this application, intended to enable those skilled in the art to make and use the content of this application. Various partial modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this application. Therefore, this application is not limited to the embodiments shown, but rather to the widest scope consistent with the claims.
[0029] For samples requiring analysis using transmission electron microscopy (TEM), focused ion beam (FIB) sample preparation is employed. During sample preparation, reference is made to… Figure 1 First, the sample 10 is placed in the recess 21 at the top of the sample stage 20, so that there are multiple contact points 30a, 30b, 30c and 30d between the sample 10 and the side of the recess 21. The sample is then welded to the recess using tungsten (W) or platinum (Pt) welding through the gas injection system (GIS) 40 of the FIB machine. Subsequently, the sample is thinned using FIB.
[0030] However, because the gas injection system's gas needle can only be located on one side of the sample stage, it can only target certain contact points (such as...). Figure 1 and Figure 2Welding is performed at the contact points 30a and 30b shown, which reduces the connection strength between the sample 10 and the recess 21. When the sample stage 20 is moved, the sample 10 may fall off the sample stage 20, causing the sample 10 to be scrapped.
[0031] In addition, the welding materials used for welding via the gas injection system 40, such as tungsten and platinum, are expensive, which greatly increases the cost of characterizing the samples.
[0032] This application provides a sample welding method, comprising: providing a sample stage, the sample stage including at least one recess; placing the sample on top of at least one of the recesses, the sample having at least one contact point with the side of the recess; and using ion etching to etch a region near the contact point so that byproducts sputtered during the ion etching process are at least partially deposited at the contact point and the sample is fixedly connected to the side of the recess.
[0033] This application utilizes ion etching to deposit byproducts sputtered during the ion etching process at the contact points where the sample contacts the side of the sample stage recess, thus fixing the sample to the sample stage. During this process, the ion etching target is the sample stage, eliminating the need for expensive welding materials such as tungsten or platinum. Furthermore, the sample welding method provided in this application can fix all contact points between the sample and the side of the sample stage recess, improving the connection strength between the sample and the sample stage and reducing the sample detachment rate.
[0034] The sample welding method provided in this application will be described in detail below with reference to specific embodiments and accompanying drawings.
[0035] refer to Figures 3-6 This application provides a sample welding method, comprising the following steps:
[0036] S1: A sample stage 200 is provided, the sample stage 200 including a recess 201;
[0037] S2: The sample 100 is placed on the top of the recess 201, and the sample 100 has at least one contact point 300 with the side of the recess 201.
[0038] S3: Ion etching is used to etch the region 202 near the contact point 300 (hereinafter referred to as "etched region 202"), so that the byproducts sputtered by the ion etching are at least partially deposited at the contact point 300 and the sample 100 is fixedly connected to the side of the recess 201.
[0039] It should be noted that, for the sake of convenience, the term "welding" is used in this application specification to summarize and refer to the process of "byproducts being deposited at the contact point 300 and the sample 100 being fixedly connected to the side of the recess 201".
[0040] In some embodiments, the sample stage 200 is cylindrical, such as a cylinder or a prism.
[0041] In some embodiments, the sample stage 200 is made of copper.
[0042] In some embodiments, reference Figure 7 The sample stage 200 includes multiple columns, and each column has a recess 201 on its top surface. By placing multiple samples 100 into the recess 201 and welding them, multiple samples can be welded on one sample stage, thereby improving welding efficiency.
[0043] In some embodiments, the sample stage 200 is a conventional sample stage for a TEM, such as a 3-column sample stage.
[0044] In some embodiments, the recess 201 is located on the top surface of the sample stage 200 to accommodate the sample 100. During the ion etching process, the byproducts generated by the ion etching can not only be deposited from above the sample 100 to the contact point 300 between the sample 100 and the recess 201, but can also enter the recess 201 and be deposited from below the sample 100 to the contact point 300 between the sample 100 and the recess 201.
[0045] In some embodiments, the width of the recess 201 gradually decreases from the top surface to the bottom surface. For example, the cross-section of the recess 201 along the direction perpendicular to its length is an inverted triangle or an inverted trapezoid, thereby allowing the sample 100 to be held in place at the top of the recess 201. Definition Figures 4-6 In the diagram, the X direction is the length direction of the recess 201, and the Y direction is the width direction of the recess 201.
[0046] In some embodiments, the length of the recess 201 gradually increases from the top surface to the bottom surface. For example, the cross-section of the recess 201 along the direction perpendicular to the width of the recess 201 is trapezoidal, so that byproducts generated during ion etching are more easily sputtered into the interior of the recess 201.
[0047] In some embodiments, the ion etching method is focused ion beam etching.
[0048] In some embodiments, the focused ion beam etching is performed using the pattern mode of a focused ion beam (FIB) machine.
[0049] During the etching process, high-energy ions released by the FIB instrument etch the etching area 202 on the side of the sample stage 200. During the etching process, the ions react with the sample stage 200 to generate ionic byproducts. These byproducts are sputtered into the recess 201, reaching the area around the contact point 300 between the sample 100 and the side of the recess 201, or directly sputtered from above the sample 100 to the vicinity of the contact point 300. They accumulate and deposit around the contact point 300, thus achieving a fixed connection between the sample 100 and the recess 201 (i.e., the sample stage 200). In some embodiments, by adjusting the size of the etching area 202 and the duration of ion etching, the byproducts can completely fill the recess 201, thereby enveloping the sample 100 and resulting in a stronger weld.
[0050] In some embodiments, the current of the focused ion beam etching is 0.9–1.1 nA, for example, 0.9 nA, 1.0 nA, or 1.1 nA. If the current is too small, the etching deposition rate will slow down and the time will increase; if the current is too large, the etching range will increase and the sample deposition effect will be affected. The voltage of the focused ion beam etching is 25–35 kV, for example, 25 kV, 30 kV, or 35 kV. The duration of the focused ion beam etching is 30–40 s, for example, 30 s, 35 s, or 40 s.
[0051] In some embodiments, the ion source used for the focused ion beam etching is a Ga gallium ion source.
[0052] In some embodiments, the etched region 202 is disposed close to the contact point 300 to ensure that byproducts generated by ion etching can be deposited at the contact point 300.
[0053] In some embodiments, the etched region 202 is disposed close to the contact point 300. In some embodiments, the distance between the edge of the etched region 202 near the contact point 300 and the contact point 300 is 1–2 μm, to ensure that byproducts generated by ion etching can be deposited near the contact point 300. In some embodiments, the distance between the edge of the etched region 202 near the contact point 300 and the contact point 300 is 1 μm, 1.5 μm, or 2 μm. The distance between the edge of the etched region 202 near the contact point 300 and the contact point 300 should not be less than 1 μm; if the distance is less than 1 μm, there is a risk of damaging the sample.
[0054] In some embodiments, the sample 100 has four contact points 300 with the side of the recess 201. For common FIB (Film Embedding) machines, only one side of the sample stage 200 can be ion-etched. Therefore, during ion etching, only the area near the contact points 300 facing the etching direction can be etched. However, this does not mean that the etching area 202 described in this application can only be located near the contact points 300 facing the etching direction. When using a machine capable of etching the sample stage 200 from both sides or at multiple angles, the etching area 202 can also be located near all four contact points 300.
[0055] Additionally, it should be noted that even if the etched area 202 is only located near the contact point 300 facing the etching direction, unlike the prior art where the gas needle can only weld a single selected contact point 300, during the ion etching process, the sputtering of by-products is random and non-directional. Therefore, by-products can be sputtered and deposited near all contact points 300, thereby fixing all contact points 300 to the recess 201.
[0056] In some embodiments, the number of etched regions 202 is multiple. Preferably, in some embodiments, the number of etched regions 202 is two, and the two etched regions 202 are respectively disposed near the two contact points 300 facing the etching direction. Since each etched region 202 needs to be ion-etched individually, reducing the number of etched regions 202 can improve welding efficiency while satisfying the welding effect. By reasonably setting the size of the etched regions 202, it is possible to improve welding efficiency while satisfying the requirement of welding all contact points 300 of the sample 100 to the side of the recess 201.
[0057] In some embodiments, the etched area 202 is a square or a rectangle. Setting the etched area 202 to a square or rectangle is to adapt to the common graphic pattern patterns of FIB machines, facilitating the selection of the etched area 202 through the graphic pattern.
[0058] In some embodiments, the area of a single etched region 202 is 1.8–2.4 μm. 2 For example, 1μm*2μm, 1.1μm*2μm or 1μm*2.4μm.
[0059] In some embodiments, the sample 100 is square, and the periphery of the sample 100 includes four contact points 300 that directly contact the sides of the recess 201. In some embodiments, there is partial line contact between the sample 100 and the recess 201; for example, the two bottom edges of the sample 100 contact the sides of the recess 201.
[0060] In some embodiments, the process by which an operator welds a sample to a sample stage using the sample welding method provided in this application is as follows:
[0061] The operator places the sample 100 on the top surface of the recess 201, making the sample 100 contact the recess 201. Then, the sample stage 200 is placed in the FIB machine, the relevant parameters for focused ion beam etching are set, and the pattern mode configured in the FIB machine is used to sequentially select a single etching area 202 on the side of the sample stage 200 and perform focused ion beam etching on the selected etching area 202. During the etching process, the sputtered byproducts enter the recess 201, are deposited at the contact point 300 between the sample 100 and the recess 201, and the contact point 300 is fixedly connected to the side of the recess 201, thereby welding the sample 100 to the sample stage 200.
[0062] This application also provides a sample preparation method, comprising: cutting a sample 100 to expose the cross-section of the sample 100 to be observed; welding the sample to a sample stage 200 using the sample welding method described in this application; and thinning the sample 100 to a set thickness. Except for the sample welding step, the remaining steps of the sample preparation method are conventional steps for preparing TEM samples using a FIB substrate, and will not be described in detail here for the sake of brevity.
[0063] The beneficial effects of the sample welding method provided in this application include, but are not limited to, the following:
[0064] This application uses ion etching to fix the contact point between the sample and the side of the sample stage recess to the side of the recess using the byproducts sputtered during the ion etching process. During the process, the sample stage is the object of ion etching, and there is no need to provide additional high-cost welding materials such as tungsten or platinum, thus reducing the cost of sample welding.
[0065] Furthermore, the sample welding method provided in this application can achieve fixed connection of all contact points between the sample and the side of the sample stage recess through the side of the recess by sputtering, thereby improving the connection strength between the sample and the sample stage and reducing the sample drop rate from the sample stage.
[0066] In summary, after reading this application, those skilled in the art will understand that the foregoing application content is presented by way of example only and is not restrictive. Although not explicitly stated herein, those skilled in the art will understand that this application is intended to encompass various reasonable changes, improvements, and modifications to the embodiments. These changes, improvements, and modifications are all within the spirit and scope of the exemplary embodiments of this application.
[0067] It should be understood that the term "and / or" as used in this embodiment includes any or all combinations of one or more of the associated listed items. It should be understood that when an element is referred to as "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be an intermediate element.
[0068] Similarly, it should be understood that when an element such as a layer, region, or substrate is referred to as being "on" another element, it may be directly on that other element, or there may be intermediate elements present. Conversely, the term "directly" means without intermediate elements. It should also be understood that the terms "comprising," "including," "including," or "comprises," as used in this application, indicate the presence of the described features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof.
[0069] It should also be understood that although the terms first, second, third, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Therefore, without departing from the teachings of this application, a first element in some embodiments may be referred to as a second element in other embodiments. The same reference numerals or the same reference signs denote the same elements throughout the specification.
[0070] Furthermore, this application specification describes exemplary embodiments by referring to idealized exemplary cross-sectional views and / or plan views and / or perspective views. Therefore, differences from the illustrated shapes are foreseeable due to factors such as manufacturing techniques and / or tolerances. Thus, exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but should include deviations in shape caused, for example, by manufacturing processes. For instance, etched areas shown as rectangular typically have circular or curved features. Therefore, the regions shown in the figures are substantially schematic, and their shapes are not intended to illustrate the actual shape of the regions of the device, nor are they intended to limit the scope of the exemplary embodiments.
Claims
1. A sample welding method, characterized in that, include: A sample stage is provided, the sample stage including at least one recess; The sample is placed on top of at least one of the recesses, and the sample has at least one contact point with the side of the recess; as well as The area near the contact point is etched by ion etching so that the byproducts sputtered during the ion etching process are at least partially deposited at the contact point and the sample is fixedly connected to the side of the recess.
2. The sample welding method according to claim 1, characterized in that, The ion etching method is focused ion beam etching.
3. The sample welding method according to claim 2, characterized in that, The focused ion beam etching is performed using the graphic mode of a focused ion beam machine.
4. The sample welding method according to claim 3, characterized in that, The current for the focused ion beam etching is 0.9–1.1 nA; the voltage for the focused ion beam etching is 25–35 kV; and the duration of the focused ion beam etching is 30–40 s.
5. The sample welding method according to claim 4, characterized in that, The ion source used in the focused ion beam etching is a Ga gallium ion source.
6. The sample welding method according to claim 1, characterized in that, The distance between the etched area and the contact point is 1 to 2 μm.
7. The sample welding method according to claim 1, characterized in that, The sample has four contact points with the side of the recess; and the number of etched areas is two.
8. The sample welding method according to claim 1, characterized in that, The sample stage includes multiple columns, and the top surface of each column is provided with the recess.
9. The sample welding method according to claim 1, characterized in that, The sample stage is made of copper.
10. A sample preparation method, characterized in that, include: The sample is cut to expose the cross-section that needs to be observed. The sample is welded to the sample stage using the sample welding method according to any one of claims 1 to 9; as well as The sample is thinned to a set thickness.