Wafer sample analysis method and device

Abstract

The present application provides a wafer sample analysis method and device. The method is applied to a secondary ion mass spectrometer, and includes: providing a wafer sample, the wafer sample includes at least one bevel, the bevel is used to expose a substrate, a first protective layer and a first doping layer on the same surface, wherein the first protective layer is formed on the substrate, and the first doping layer is formed on the first protective layer; obtaining a bevel image of the bevel and analyzing the bevel image to obtain the doping depth and doping concentration of the elements in the wafer sample in the bevel image. The wafer sample analysis method and device provided in the present application solve the problem of inaccurate analysis results in existing methods for analyzing elements in wafers.

Description

Technical Field

[0001] The present application relates to semiconductor detection technology, and in particular to a wafer sample analysis method and device. Background Art

[0002] Wafer refers to the silicon chip used in the manufacture of silicon semiconductor integrated circuits. Because of its round shape, it is called a wafer. Various circuit element structures can be processed on the wafer to form semiconductor components with specific electrical functions. However, the doping of group III and group V elements in the wafer plays a decisive role in regulating the electrical properties of semiconductor components. Therefore, in the semiconductor industry, it is necessary to detect the type, quantity and distribution of group III and group V elements in the wafer.

[0003] At present, the industry generally uses secondary ion mass spectrometer (Sims) to detect the types, quantities and distribution of group III and group V elements in wafers. The secondary ion mass spectrometer bombards the sample surface with a high-energy primary ion beam, causing atoms or atomic groups on the sample surface to absorb energy and sputter from the surface to produce secondary ions. After these charged ions pass through the mass analyzer, a spectrum of information about the sample surface can be obtained. However, Sims analysis directly bombards the surface of the wafer sample with ion beams. Since the surface of the sample will be exposed to the air before Sims analysis, it will cause surface contamination. The surface effect will affect the collection of surface signals. As the depth of ion sputtering increases, the sidewall effect will gradually increase, that is, the ions on the sidewalls of the ion beam bombardment site will mix with the ions that have been generated before to produce mixed ions. In the subsequent analysis process, the mixed ions have a greater impact on the analysis of the true element doping depth. Therefore, the existing methods for analyzing elements in wafer samples have the problem of inaccurate analysis results. Summary of the invention

[0004] The present application provides a wafer sample analysis method and device to solve the problem of inaccurate analysis results when analyzing elements in wafer samples in the prior art.

[0005] On the one hand, the present application provides a wafer sample analysis method, applied to a secondary ion mass spectrometer, comprising:

[0006] Providing a wafer sample, wherein the wafer sample comprises at least one inclined surface, wherein the inclined surface is used to expose a substrate, a first protective layer, and a first doping layer on the same surface, wherein the first protective layer is formed on the substrate, and the first doping layer is formed on the first protective layer;

[0007] An inclined plane image of the inclined plane is acquired and analyzed to obtain the doping depth and doping concentration of the elements in the wafer sample in the inclined plane image.

[0008] In one embodiment, the substrate includes a first part and a second part, wherein the first part is single crystal silicon and the second part is doped single crystal silicon; the first protective layer is formed on the doped single crystal silicon.

[0009] In one embodiment, acquiring a bevel image of the bevel and analyzing the bevel image to obtain the doping depth and doping concentration of elements in the wafer sample in the bevel image includes:

[0010] Determine a first length of the first protective layer along the inclined surface direction according to the inclined surface image;

[0011] Determine a second length of the doped single crystal silicon along the inclined surface direction according to the inclined surface image;

[0012] Obtaining the thickness of the first protective layer along a direction perpendicular to the substrate to obtain the thickness of the first protective layer;

[0013] Determine the doping depth according to the first length, the second length and the thickness of the first protective layer;

[0014] Determining the doping concentration corresponding to the doping depth according to the inclined plane image;

[0015] An analysis result graph is drawn according to the doping depth and the doping concentration corresponding to the doping depth.

[0016] In one embodiment, the wafer sample further includes a second protective layer formed on the first doping layer.

[0017] In one embodiment, the first protective layer and the second protective layer are composed of silicon compounds.

[0018] In one embodiment, the first doping layer is formed on the first protective layer by low pressure chemical vapor deposition, and the first doping layer includes boron.

[0019] In one embodiment, the doping concentration in the wafer sample is generated by bombardment of an ion beam with a preset energy.

[0020] In one embodiment, the angle between the inclined surface and the plane where the substrate is located is less than or equal to 10°.

[0021] On the other hand, the present application also provides a wafer sample analysis device, comprising:

[0022] A processing module, used for acquiring an inclined plane image of the inclined plane and analyzing the inclined plane image to obtain a doping depth and a doping concentration of elements in the wafer sample in the inclined plane image;

[0023] The wafer sample comprises at least one inclined surface, and the inclined surface is used to expose the substrate, the first protection layer and the first doping layer on the same surface, wherein the first protection layer is formed on the substrate, and the first doping layer is formed on the first protection layer.

[0024] In one embodiment, the substrate includes a first part and a second part, wherein the first part is single crystal silicon and the second part is doped single crystal silicon; the first protective layer is formed on the doped single crystal silicon.

[0025] After the staff dopes the III group elements and the V group elements into the wafer, it is necessary to know the depth of element doping and the element doping concentration corresponding to different doping depths. The wafer sample analysis method provided in this embodiment prepares at least one inclined surface for exposing the substrate, the first protective layer and the first doping layer of the wafer sample to be analyzed. Then, by analyzing the inclined surface image of the wafer sample, an analysis result diagram of the doping depth and doping concentration of the elements in the wafer sample is obtained. Since the inclined surface image is an image obtained by the secondary ion mass spectrometer directly bombarding the inclined surface of the wafer sample with an ion beam, the inclined surface image includes the element distribution information of all layers of the wafer sample. Therefore, unlike the result of the elements of the side wall of the ion beam impact part mixed with the elements produced by the high-energy ion beam impact part as the ion sputtering depth increases in the prior art, the inclined surface image obtained in this application does not have the problem of element mixing interference, and the element analysis results obtained by analyzing the inclined surface image, that is, the doping depth of the element and the doping concentration of the element are more accurate. In addition, the first protective layer provided in the present application can solve the problem of inaccurate element analysis results caused by surface contamination of wafer samples, and the first doping layer can also solve the problem of inaccurate calculation of element doping depth in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0027] Figure 1 Schematic diagram of the application of the secondary electron mass spectrometer provided for this application.

[0028] Figure 2 A schematic flow chart of a wafer sample analysis method provided for one embodiment of the present application.

[0029] Figure 3 A schematic diagram of a wafer sample provided for one embodiment of the present application.

[0030] Figure 4 A schematic flow chart of a wafer sample analysis method provided in accordance with another embodiment of the present application.

[0031] Figure 5 A schematic diagram of an analysis result graph provided for one embodiment of the present application.

[0032] Figure 6 A schematic diagram of a wafer sample provided for yet another embodiment of the present application.

[0033] Figure 7 A schematic diagram of a wafer sample analysis device provided for one embodiment of the present application.

[0034] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0035] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0036] The existing SIMS method for analyzing doped elements in wafer samples has the problem of inaccurate analysis results. Based on this, the present application provides a wafer sample analysis method, which is applied to a secondary ion mass spectrometer. The wafer sample analysis method provides a wafer sample including a bevel, and generates secondary ions by acquiring an image of the bevel of the wafer sample, and analyzing the image of the bevel by ion beam bombardment. The secondary ions are analyzed to obtain a map of the element doping depth of the wafer sample and the element doping concentration corresponding to different depths. Because the bevel image includes a cross-sectional image of multiple layers in the wafer sample. At this time, the doping depth and corresponding element doping concentration of the element in the wafer sample can be determined without bombarding the wafer sample by continuously deepening the bombardment depth with an ion beam, so there will be no sidewall effect, and the analysis results of the elements in the obtained wafer will be more accurate. In addition, the wafer sample analysis method provided in the present application also forms a first protective layer and a first doping layer on the substrate of the wafer sample. The protective layer can effectively prevent surface contamination of the wafer sample, thereby making the analysis results of the elements in the wafer sample more accurate. It should be noted that the analysis of the elements in the wafer sample includes analysis of the doping type, doping depth and doping concentration of the elements.

[0037] See also Figure 1 The wafer sample analysis method provided in the present application is applied to a secondary ion mass spectrometer, which includes an ion source and a secondary electron imaging system. The ion source generates primary ions, which bombard the inclined surface of the wafer sample to generate secondary ions, and the secondary electron imaging system is used to generate a secondary electron image of the secondary ions, that is, an inclined surface image of the wafer sample. The element analysis system in the secondary ion mass spectrometer determines the doping depth and doping concentration of the elements in the wafer sample after analyzing the inclined surface image.

[0038] Please also see Figure 2 The present application provides a wafer sample analysis method, which is applied to a secondary ion mass spectrometer, comprising:

[0039] S201, providing a wafer sample, wherein the wafer sample comprises at least one inclined surface, wherein the inclined surface is used to expose a substrate, a first protective layer and a first doping layer on the same surface, wherein the first protective layer is formed on the substrate, and the first doping layer is formed on the first protective layer.

[0040] Please also see Figure 3 , the wafer sample can be ground and polished to obtain the bevel, and the bevel is used to expose the substrate, the first protective layer and the first doping layer of the wafer sample on the same surface. The first protective layer is formed on the substrate, and the first doping layer is formed on the first protective layer. The first protective layer is to prevent the surface of the wafer sample from being contaminated, and the first doping layer is to mark the surface position of the first protective layer. The thickness of the first protective layer and the first doping layer can be selected according to actual needs, and the present application does not limit it. In an optional embodiment, the first protective layer can be a film formed by a silicon compound. The bevel morphology of the wafer sample obtained after grinding and polishing should meet the sample specifications of the secondary ion mass spectrometer. The angle between the bevel and the plane where the substrate is located can be selected according to actual needs, and the present application does not limit it.

[0041] S202, acquiring a bevel image of the bevel and analyzing the bevel image to obtain a doping depth and a doping concentration of elements in the wafer sample in the bevel image.

[0042] The secondary ion mass spectrometer is provided with a secondary electron imaging system, and the inclined plane image is obtained by the secondary electron imaging system by analyzing the secondary ions sputtered on the inclined plane. The inclined plane image can be an image of the entire inclined plane, or an image of the bombardment area selected by the staff according to actual needs. For example, the staff first selects the area on the inclined plane to be bombarded by the ion beam, and then selects the image collected in the preset area of ​​the inclined plane after the ion beam bombardment as the inclined plane image. After obtaining the inclined plane image, the element analysis system in the secondary ion mass spectrometer determines the doping depth of the elements in the wafer sample and the doping concentration corresponding to different doping depths through the inclined plane image. The element doping refers to doping the III group elements and the V group elements in the wafer sample. If the inclined plane image is the entire image of the inclined plane, the doping depth and the doping concentration finally determined are the doping depth and the doping concentration of the elements within the inclined plane range after the inclined plane is bombarded by the ion beam. If the inclined surface image is only an image of the area on the inclined surface selected by the staff to be bombarded by the ion beam, the doping depth and the doping concentration finally determined are the element doping depth and doping concentration of the image of the area selected by the staff.

[0043] After the staff dopes the III group elements and the V group elements into the wafer, it is necessary to know the depth of the element doping and the element doping concentration corresponding to different depths. The wafer sample analysis method provided in this embodiment prepares at least one substrate, a first protective layer and a first doping layer bevel for exposing the wafer sample from the wafer sample to be analyzed. Then, by analyzing the bevel image of the wafer sample, an analysis result diagram of the doping depth and doping concentration of the elements in the wafer sample is obtained. Since the bevel image is an image obtained by the secondary ion mass spectrometer directly bombarding the bevel of the wafer sample with an ion beam, the bevel image includes the element distribution information of all layers of the wafer sample. Therefore, unlike the result of the elements generated by the high-energy ion beam impacting the side wall of the ion beam impacting part as the ion sputtering depth increases in the prior art, the bevel image obtained in this application does not have the problem of element mixing interference, and the element analysis results obtained by analyzing the bevel image, that is, the element doping depth and element doping concentration are more accurate. In addition, the first protective layer and the first doping layer provided in this application can also solve the problem of inaccurate element analysis results caused by surface contamination of wafer samples.

[0044] In one embodiment of the present application, the substrate includes a first portion and a second portion, wherein the first portion is single crystal silicon and the second portion is doped single crystal silicon. The first protective layer is formed on the doped single crystal silicon. After acquiring the oblique image, the doping depth and doping concentration of the element doped in the second portion are mainly analyzed.

[0045] Please also see Figure 4 , the step S202 includes:

[0046] S401, determining a first length of the first protective layer along the inclined surface direction according to the inclined surface image.

[0047] like Figure 3 As shown, the extension direction of the line where the inclined surface intersects the side wall of the wafer sample is the direction of the inclined surface, and the plane where the side wall is located is perpendicular to the plane where the substrate and the first protective layer are located. The first length is Figure 3 L1 shown in .

[0048] S402, determining a second length of the doped single crystal silicon along the inclined surface direction according to the inclined surface image.

[0049] The second length is Figure 3 L2 shown in . The first length and the second length can be measured by a secondary ion mass spectrometer through the oblique image.

[0050] S403, obtaining the thickness of the first protective layer along a direction perpendicular to the substrate to obtain the thickness of the first protective layer.

[0051] The thickness of the first protective layer can be measured by a worker.

[0052] S404, determining the doping depth according to the first length, the second length and the thickness of the first protective layer.

[0053] The secondary ion mass spectrometer is provided with a calculation program, and the staff can input the thickness of the first protective layer into the calculation program. The calculation program is provided with a calculation formula: Wherein, D represents the doping depth of the element in the wafer sample; L1 represents the first length, L2 represents the second length, and L represents the thickness of the first protective layer. The calculation program in the secondary ion mass spectrometer can determine the doping depth of the element in the wafer sample.

[0054] S405, determining the doping concentration corresponding to the doping depth according to the inclined surface image.

[0055] The oblique surface image is a secondary electron image, and the secondary ion mass spectrometer can determine the doping concentration data corresponding to each depth data in the doping depth according to the secondary electron image.

[0056] S406, plotting an analysis result graph according to the doping depth and the doping concentration corresponding to the doping depth.

[0057] Please refer to Figure 5, the secondary ion mass spectrometer can draw the analysis result diagram according to the determined doping depth of the element in the wafer sample and the doping concentration corresponding to different doping depths through the analysis software. The analysis software is Win Image and Win Curve data processing software. The horizontal coordinate of the analysis result diagram can be the doping concentration of the element, and the vertical coordinate of the analysis result diagram can be the doping depth of the element. The analysis result diagram displays multiple data of the doping depth in the form of a curve, as well as the corresponding relationship between the data of multiple doping depths and multiple data of the doping concentration. The doping depth corresponding to the maximum doping concentration of the element in the wafer sample can also be known through the analysis result diagram. If the inclined plane image is an image of a partial area on the inclined plane selected by the staff, the image of the partial area is defined as a preset area image here, and the preset area image corresponds to a preset depth area. The staff can determine the doping concentration area of ​​the element corresponding to the preset depth area through the analysis result diagram, that is, after selecting the preset depth area on the vertical coordinate of the analysis result diagram, the doping concentration area of ​​the element corresponding to the preset depth area can be determined accordingly.

[0058] In an optional embodiment, the analysis result graph may also be replaced by an analysis result table or other data display formats, as long as the doping depth and corresponding doping concentration of the elements in the wafer sample can be displayed.

[0059] Please also see Figure 6 In one embodiment of the present application, the wafer sample further includes a second protective layer, and the second protective layer is formed on the first doped layer. The element composition of the second protective layer and the first protective layer may be the same. The first protective layer and the second protective layer may be composed of silicon compounds. The thickness of the second protective layer may be selected according to actual needs, and is not limited in the present application. The second protective layer can ensure that the analysis results are more accurate.

[0060] In one embodiment of the present application, the first doping layer is formed on the first protective layer by low pressure chemical vapor deposition, and the first doping layer includes boron. The first doping layer is used to mark the position of the surface of the first protective layer. Figure 5 As shown, the analysis result diagram can display the position of the surface of the first protective layer marked by the first doping layer by displaying the marking line of the element depth and concentration of the first doping layer. The first doping layer can also prevent the surface of the first protective layer from being contaminated, thereby improving the accuracy of the analysis results of the doping depth and corresponding doping concentration of the elements in the wafer sample. The boron element in the first doping layer can also be replaced by other elements as long as the function of marking the surface position of the first protective layer can be achieved.

[0061] In one embodiment of the present application, the doping concentration in the wafer sample is generated by bombardment of an ion beam with a preset energy. The preset energy can be set by a staff member, and the principle of setting is to improve the spatial resolution of the oblique image.

[0062] In one embodiment of the present application, the angle between the inclined surface and the plane where the substrate is located is less than or equal to 10°. Figure 6 As shown, the angle a is less than or equal to 10°. The more completely the inclined plane can display the cross section of the wafer sample, the more completely and accurately the inclined plane image obtained based on the inclined plane can reflect the doping depth and doping concentration of the elements in the wafer sample.

[0063] See also Figure 7 The present application provides a wafer sample analysis device 10, comprising:

[0064] The processing module 11 is used to obtain a bevel image of the bevel and analyze the bevel image to obtain the doping depth and doping concentration of the elements in the wafer sample in the bevel image;

[0065] The wafer sample at least comprises a bevel, and the bevel is used to expose a substrate, a first protection layer and a first doping layer on the same surface, wherein the first protection layer is formed on the substrate, and the first doping layer is formed on the first protection layer.

[0066] The substrate comprises a first part and a second part, wherein the first part is single crystal silicon and the second part is doped single crystal silicon; the first protection layer is formed on the doped single crystal silicon.

[0067] The wafer sample also includes a second protection layer formed on the first doping layer.

[0068] The first protective layer and the second protective layer are composed of a silicon compound.

[0069] The first doping layer is formed on the first protective layer by low pressure chemical vapor deposition, and the first doping layer includes boron element.

[0070] The doping concentration in the wafer sample is generated by bombardment of an ion beam with a preset energy.

[0071] The included angle between the inclined surface and the plane where the substrate is located is less than or equal to 10°.

[0072] The processing module is specifically used for:

[0073] Determine a first length of the first protective layer along the inclined surface direction according to the inclined surface image;

[0074] Determine a second length of the doped single crystal silicon along the inclined surface direction according to the inclined surface image;

[0075] Obtaining the thickness of the first protective layer along a direction perpendicular to the substrate to obtain the thickness of the first protective layer;

[0076] Determine the doping depth according to the first length, the second length and the thickness of the first protective layer;

[0077] Determine the doping concentration corresponding to the doping depth according to the inclined plane image;

[0078] An analysis result graph is drawn according to the doping depth and the doping concentration corresponding to the doping depth.

[0079] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0080] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0081] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0082] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A wafer sample analysis method, characterized in that: Applied to a secondary ion mass spectrometer, the method comprises: Providing a wafer sample, the wafer sample comprising at least one inclined surface, the inclined surface being used to expose a substrate, a first protective layer and a first doped layer on the same surface, wherein the first protective layer is formed on the substrate, and the first doped layer is formed on the first protective layer; the substrate comprising a first portion and a second portion, wherein the first portion is single crystal silicon, and the second portion is doped single crystal silicon; the first protective layer is formed on the doped single crystal silicon; Acquire an inclined plane image of the inclined plane and analyze the inclined plane image to obtain a doping depth and a doping concentration of elements in the wafer sample in the inclined plane image; Wherein, acquiring the inclined plane image of the inclined plane and analyzing the inclined plane image to obtain the doping depth and doping concentration of the elements in the wafer sample in the inclined plane image comprises: Determine a first length of the first protective layer along the inclined surface direction according to the inclined surface image; Determine a second length of the doped single crystal silicon along the inclined surface direction according to the inclined surface image; Obtaining the thickness of the first protective layer along a direction perpendicular to the substrate to obtain the thickness of the first protective layer; Determine the doping depth according to the first length, the second length and the thickness of the first protective layer; Determining the doping concentration corresponding to the doping depth according to the inclined plane image; An analysis result graph is drawn according to the doping depth and the doping concentration corresponding to the doping depth.

2. The method according to claim 1, characterized in that The wafer sample further includes a second protection layer formed on the first doping layer.

3. The method according to claim 2, characterized in that The first protective layer and the second protective layer are composed of a silicon compound.

4. The method according to claim 1, characterized in that The first doping layer is formed on the first protection layer by low pressure chemical vapor deposition, and the first doping layer includes boron element.

5. The method according to claim 1, characterized in that The doping concentration in the wafer sample is generated by bombardment of an ion beam with a preset energy.

6. The method according to claim 1, characterized in that The included angle between the inclined surface and the plane where the substrate is located is less than or equal to 10°.

7. A wafer sample analysis device, characterized in that: include: A processing module, used for acquiring an inclined plane image of the inclined plane and analyzing the inclined plane image to obtain a doping depth and a doping concentration of elements in the wafer sample in the inclined plane image; The wafer sample comprises at least one inclined surface, and the inclined surface is used to expose the substrate, the first protective layer and the first doping layer on the same surface, wherein the first protective layer is formed on the substrate, and the first doping layer is formed on the first protective layer, and the substrate comprises a first part and a second part, wherein the first part is single crystal silicon, and the second part is doped single crystal silicon; the first protective layer is formed on the doped single crystal silicon; Wherein, acquiring the inclined plane image of the inclined plane and analyzing the inclined plane image to obtain the doping depth and doping concentration of the elements in the wafer sample in the inclined plane image comprises: Determine a first length of the first protective layer along the inclined surface direction according to the inclined surface image; Determine a second length of the doped single crystal silicon along the inclined surface direction according to the inclined surface image; Obtaining the thickness of the first protective layer along a direction perpendicular to the substrate to obtain the thickness of the first protective layer; Determine the doping depth according to the first length, the second length and the thickness of the first protective layer; Determining the doping concentration corresponding to the doping depth according to the inclined plane image; An analysis result graph is drawn according to the doping depth and the doping concentration corresponding to the doping depth.

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