Wafer and manufacturing method thereof, and method for detecting trace metal in wet etching liquid
By forming PN junctions in the wafer and forming an N-type conductive type crystal rod grown by direct-pullization method during cooling, the problem of low sensitivity and accuracy of detecting trace metals in the wet etching liquid in the prior art is solved, and more efficient trace metal detection is achieved.
Patent Information
- Application Number
- CN202411997498.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2025-04-11
AI Technical Summary
In the prior art, the sensitivity and accuracy of detecting trace metals in wet etching liquid are low, making it difficult to accurately detect whether trace metals are present in wet etching liquid.
The P-type conductive type crystal rod is grown by direct drawing method, and the N-type conductive type region is formed through the thermal donor defect during the cooling process, forming wafers including the P-type conductive type and the N-type conductive type region, and the adsorption ability to trace metal is enhanced by using the PN junction.
By forming a PN junction, the wafer's adsorption ability to trace metals in the wet etching liquid is significantly improved, thereby improving the detection sensitivity and accuracy.
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Figure CN119812056A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of semiconductor technology, and in particular to a wafer and a method for manufacturing the same, and a method for detecting trace metals in a wet etching solution. Background Art
[0002] In the semiconductor manufacturing process, trace metals such as nickel are widely present in the wet etching solution used in the wet etching process in semiconductor manufacturing. These trace metals can easily diffuse into the silicon wafer, thus adversely affecting subsequent processing and equipment performance. Therefore, it is necessary to detect the trace metals in the wet etching solution to determine whether there are trace metals in the wet etching solution.
[0003] However, the sensitivity and accuracy of the method for detecting trace metals in the wet etching solution in the related art are low, and it is difficult to accurately detect whether there are trace metals in the wet etching solution. Summary of the invention
[0004] A series of simplified concepts are introduced in the Summary of the Invention section, which will be further described in detail in the Detailed Description of the Invention section. The Summary of the Invention section of this application does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.
[0005] In view of the existing problems, the present application provides a method for manufacturing a wafer, wherein the wafer is used to detect trace metals in a wet etching solution, and the method comprises:
[0006] Growing a P-type conductive type crystal rod by a Czochralski method, wherein, during the cooling process of the crystal rod, a region of N-type conductive type is formed in the crystal rod under the influence of heated donor defects;
[0007] The crystal rod is processed to obtain a wafer, wherein the wafer includes a P-type conductive region and an N-type conductive region.
[0008] Exemplarily, in the process of growing the crystal rod by the Czochralski method, the resistivity of the crystal rod is greater than or equal to 10 ohm·cm and less than or equal to 500 ohm·cm.
[0009] Exemplarily, in the process of growing the crystal rod by the Czochralski method, the oxygen content of the crystal rod is greater than or equal to 10 ppma and less than or equal to 20 ppma.
[0010] Exemplarily, in the process of growing the crystal rod by the Czochralski method, the pulling speed of the crystal rod is greater than or equal to 0.3 cm / min and less than or equal to 1 cm / min.
[0011] Exemplarily, the potential difference of the electric field generated by the P-type conductive region and the N-type conductive region in the wafer is greater than or equal to 0.3V and less than or equal to 0.5V.
[0012] Exemplarily, the N-type conductive area in the wafer is an annular area whose center coincides with the center of the wafer.
[0013] On the other hand, the present application provides a wafer, which is used to detect trace metals in a wet etching solution, and the wafer is manufactured using the aforementioned manufacturing method.
[0014] In another aspect, the present application provides a method for detecting trace metals in a wet etching solution, comprising:
[0015] Providing a wafer manufactured by the aforementioned manufacturing method, or providing the aforementioned wafer;
[0016] Placing the wafer into a wet etching solution to perform a wet etching process;
[0017] After etching is completed, the wafer is inspected, and when trace metal is detected in the wafer, it is determined that trace metal exists in the wet etching solution.
[0018] Exemplarily, the wafer is inspected, including:
[0019] The minority carrier lifetimes of the N-type conductivity region and the P-type conductivity region in the wafer are detected, and when the detected minority carrier lifetime of the N-type conductivity region is lower than the minority carrier lifetime of the P-type conductivity region, it is determined that trace metal exists in the wafer.
[0020] Exemplarily, the wafer is inspected, including:
[0021] performing heat treatment on the wafer;
[0022] Collecting the material on the surface of the wafer by a vapor deposition tool to obtain a collected sample;
[0023] The collected samples are subjected to inductively coupled plasma mass spectrometry detection, and when trace metals are detected, it is determined that the trace metals exist in the wafer.
[0024] The wafer and its manufacturing method, and the method for detecting trace metals in wet etching solution of the embodiments of the present application, the P-type conductive area and the N-type conductive area in the wafer form a PN junction, which can enhance the wafer's ability to adsorb trace metals in the wet etching solution, thereby improving the sensitivity and accuracy of detecting trace metals in the wet etching solution. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The following drawings of the present application are used as a part of the present application for understanding the present application. The drawings show the embodiments of the present application and their descriptions, which are used to explain the principle of the present application.
[0026] In the attached figure:
[0027] Figure 1 A schematic top view of a wafer according to an exemplary embodiment of the present application is shown;
[0028] Figure 2 A schematic cross-sectional view of a wafer according to an exemplary embodiment of the present application is shown;
[0029] Figure 3 A flowchart showing a method for manufacturing a wafer according to an exemplary embodiment of the present application is shown;
[0030] Figure 4 A flow chart showing a method for detecting trace metals in a wet etching solution according to an exemplary embodiment of the present application is shown;
[0031] Figure 5 The resistivity, oxygen content and minority carrier lifetime distribution diagram of the sample A wafer according to an exemplary embodiment of the present application are shown;
[0032] Figure 6 The resistivity, oxygen content and minority carrier lifetime distribution diagram of the sample B wafer according to an exemplary embodiment of the present application are shown;
[0033] Figure 7 A comparison chart of nickel metal content obtained by inductively coupled plasma mass spectrometry detection of sample A wafer and sample B wafer according to an exemplary embodiment of the present application is shown. DETAILED DESCRIPTION
[0034] Next, the present application will be described more completely in conjunction with the accompanying drawings, in which embodiments of the present application are shown. However, the present application can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the present application to those skilled in the art. In the accompanying drawings, for clarity, the sizes and relative sizes of layers and regions may be exaggerated. The same reference numerals throughout represent the same elements.
[0035] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer or part discussed below can be represented as a second element, component, region, layer or part.
[0036] Spatially relative terms such as "under," "below," "below," "under," "above," "above," etc., may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that in addition to the orientations shown in the figures, the spatially relative terms are intended to include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "on" the other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be oriented otherwise (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.
[0037] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present application. When used herein, the singular forms "a", "an", and "said / the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.
[0038] Embodiments of the application are described herein with reference to cross-sectional views that are schematic diagrams of ideal embodiments (and intermediate structures) of the present application. Thus, variations from the shapes shown due to, for example, manufacturing techniques and / or tolerances can be expected. Therefore, embodiments of the present application should not be limited to the specific shapes of the zones shown herein, but include shape deviations due to, for example, manufacturing. For example, an implanted region shown as a rectangle typically has rounded or curved features and / or an implant concentration gradient at its edges, rather than a binary change from an implanted region to a non-implanted region. Similarly, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation is performed. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to show the actual shape of the region of the device and are not intended to limit the scope of the present application.
[0039] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by ordinary technicians in the field of this application. It will also be understood that terms such as those defined in commonly used dictionaries should be understood to have a meaning consistent with their meaning in the context of the relevant art and / or this specification, and should not be interpreted in an ideal or overly formal sense unless expressly defined as such herein.
[0040] In order to thoroughly understand the present application, detailed steps and structures will be presented in the following description to illustrate the technical solution proposed by the present application. The preferred embodiments of the present application are described in detail below, but in addition to these detailed descriptions, the present application may also have other implementations.
[0041] In the related art, a P-type wafer is generally placed in a wet etching solution for a wet etching process, and then the metal that may exist in the P-type wafer is driven out through a thermal process below 700°C, and then the material on the surface of the P-type wafer is collected through a vapor deposition tool, and then the collected material is subjected to inductively coupled plasma mass spectrometry detection to determine whether there is trace metal in the wet etching solution by detecting the trace metal in the P-type wafer.
[0042] However, the P-type wafer used in the related art for detecting trace metals in the wet etching solution has limited adsorption capacity for trace metals, resulting in low sensitivity and accuracy of the method for detecting trace metals in the wet etching solution in the related art.
[0043] Therefore, in view of the existence of the above-mentioned technical problems, the present application proposes a method for manufacturing a wafer, which is used to detect trace metals in a wet etching solution, such as Figure 3 As shown, the manufacturing method comprises the following steps:
[0044] Step S1, growing a P-type conductive type crystal rod by a Czochralski method, wherein, during the cooling process of the crystal rod, an N-type conductive type region is formed in the crystal rod due to the influence of thermal donor defects;
[0045] Step S2, processing the crystal rod to obtain a wafer, wherein the wafer includes a P-type conductive region and an N-type conductive region.
[0046] The wafer manufacturing method of the embodiment of the present application can form a wafer including a P-type conductivity type region and an N-type conductivity type region. The P-type conductivity type region and the N-type conductivity type region in the wafer form a PN junction, which can enhance the wafer's ability to adsorb trace metals in a wet etching solution, thereby improving the sensitivity and accuracy of detecting trace metals in the wet etching solution.
[0047] Below, reference Figures 1 to 3 The wafer manufacturing method of the present application is described in detail, wherein: Figure 1 FIG. 1 is a schematic top view of a wafer according to an exemplary embodiment of the present application. Figure 2 A schematic cross-sectional view of a wafer according to an exemplary embodiment of the present application is shown. Figure 3 A flow chart of a method for manufacturing a wafer according to an exemplary embodiment of the present application is shown.
[0048] For example, Figure 3 As shown, the wafer manufacturing method of the present application includes the following steps:
[0049] First, step S31 is performed to grow a P-type conductive type crystal rod by using a Czochralski method, wherein during the cooling process of the crystal rod, an N-type conductive type region is formed in the crystal rod under the influence of thermal donor defects.
[0050] In one example, the Czochralski method is also called the Czochralski method (i.e., the CZ method). In the process of growing a P-type conductive type crystal rod using the Czochralski method: first, P-type doped polysilicon (e.g., boron-doped polysilicon) is placed in a quartz crucible, and then the P-type doped polysilicon is heated by a thermal field structure to melt it into molten silicon. Then, a seed crystal is immersed in the molten silicon, and the seed crystal is pulled to solidify and grow the molten silicon at the bottom of the seed crystal, and finally a P-type conductive type crystal rod is formed. Specifically, the process of growing a P-type conductive type crystal rod using the Czochralski method may include the steps of melting, seed crystal immersion, necking, shouldering, equal diameter growth, and finishing, which will not be repeated here.
[0051] In one example, during the cooling process of a P-type conductive crystal rod grown by the Czochralski method, a thermal donor defect will be formed inside the crystal rod. The thermal donor defect is a complex precipitate of silicon oxide. During the process of growing the crystal rod by the Czochralski method, the crystal rod will inevitably contain a certain amount of oxygen impurities. During the cooling process, complex interactions will occur between oxygen atoms and silicon atoms. For example, oxygen atoms will gather together to form special structures with silicon atoms. These structures will introduce donor energy levels in the silicon bandgap, thereby forming thermal donor defects. Among them, the change in temperature is the key factor in the formation of thermal donor defects. The formation temperature of thermal donor defects is 400 degrees Celsius-600 degrees Celsius.
[0052] In one example, during the cooling process of the P-type conductive type crystal rod in the present application, the heated donor defects will form an N-type conductive type region in the crystal rod. From the perspective of the band structure, the donor energy level formed by the thermal donor defect is close to the conduction band, and can provide electrons to the conduction band, so that the electron concentration in the P-type conductive type crystal rod increases. When the electrons provided by the thermal donor defect are higher than a certain amount, part of the region in the P-type conductive type crystal rod can be transformed into an N-type conductive type region, that is, an N-type conductive type region is formed in the P-type conductive type crystal rod.
[0053] In one example, in the process of growing a crystal rod of P-type conductivity type by the Czochralski method, the resistivity of the crystal rod is greater than or equal to 10ohm·cm and less than or equal to 500ohm·cm. For example, the resistivity of the crystal rod may be 10ohm·cm, 50ohm·cm, 100ohm·cm, 200ohm·cm, 300ohm·cm, 350ohm·cm, 400ohm·cm or 500ohm·cm. Exemplarily, the resistivity of the crystal rod of P-type conductivity type is negatively correlated with the doping concentration (e.g., boron doping concentration) in the crystal rod, and the resistivity of the crystal rod can be controlled by controlling the doping concentration of the silicon melt, that is, the resistivity of the crystal rod can characterize the doping concentration in the crystal rod. Exemplarily, the resistivity of the crystal rod mentioned here is the resistivity of the P-type conductivity region of the wafer obtained below.
[0054] In one example, in the process of growing a crystal rod of P-type conductivity type by the Czochralski method, the oxygen content of the crystal rod is greater than or equal to 10 ppma and less than or equal to 20 ppma, for example, the oxygen content of the crystal rod can be 10 ppma, 11 ppma, 12 ppma, 13 ppma, 14 ppma, 15 ppma, 16 ppma, 17 ppma, 18 ppma, 19 ppma or 20 ppma. Among them, oxygen is provided by a quartz crucible, and the oxygen content of the crystal rod is a key factor affecting the formation of thermal donor defects. Exemplarily, the oxygen content of the crystal rod mentioned here is the oxygen content of the P-type conductivity type region of the wafer obtained below.
[0055] In one example, in the process of growing a P-type conductive type crystal rod by the Czochralski method, the pulling speed of the crystal rod is greater than or equal to 0.3 cm / min and less than or equal to 1 cm / min, for example, the pulling speed of the crystal rod can be 0.3 cm / min, 0.4 cm / min, 0.5 cm / min, 0.6 cm / min, 0.7 cm / min, 0.8 cm / min, 0.9 cm / min or 1 cm / min. The pulling speed of the crystal rod affects the cooling rate of the crystal rod, that is, affects the length of time the crystal rod is in a certain temperature range, for example, affects the length of time the crystal rod is in a state where thermal donor defects can be formed (for example, the length of time the crystal rod is at 400 degrees Celsius to 600 degrees Celsius), thereby affecting the formation of thermal donor defects.
[0056] In one example, in the process of growing a P-type conductive type crystal rod by the Czochralski method, the resistivity, oxygen content and pulling speed of the crystal rod are all key factors that determine whether an N-type conductive type region can be formed in the crystal rod during the cooling process. Taking the crystal rod resistivity greater than or equal to 10 ohm·cm and less than or equal to 500 ohm·cm, the crystal rod oxygen content greater than or equal to 10 ppma and less than or equal to 20 ppma, the crystal rod pulling speed greater than or equal to 0.3 cm / min and less than or equal to 1 cm / min, and the P-type conductive type crystal rod doped with boron as an example, when the resistivity, oxygen content and pulling speed of the crystal rod are within the above ranges, the boron doping concentration in the crystal rod is not too high, that is, the number of holes in the crystal rod is not too large, and at the same time, the formed thermal donor defects can provide enough electrons, that is, to ensure that the P-type conductive type crystal rod can be affected by the thermal donor defects during the cooling process and form an N-type conductive type region in the crystal rod. Exemplarily, the resistivity, oxygen content and pulling speed of the crystal rod may also be in any other suitable numerical range, as long as it can ensure that the P-type conductive type crystal rod can be affected by the thermal donor defects during the cooling process to form an N-type conductive type region in the crystal rod, and the present application does not impose any restrictions on this.
[0057] Next, step S32 is performed to process the crystal rod to obtain a wafer, wherein the wafer includes a P-type conductive region and an N-type conductive region.
[0058] In one example, the crystal rod is processed to obtain a crystal surface, including: cutting the wafer to remove the head and tail parts with smaller diameters; and then slicing, rounding, grinding, removing defects, polishing and cleaning the cut crystal rod to obtain a wafer.
[0059] In one example, if Figure 1 and Figure 2 As shown, the wafer obtained in the present application includes a P-type conductive area 110 and an N-type conductive area 120. The P-type conductive area 110 and the N-type conductive area 120 can form a PN junction, forming a perfect electroplating circuit, which can enhance the adsorption capacity of the wafer to trace metals. For example, the adsorption capacity of the wafer including the P-type conductive area 110 and the N-type conductive area 120 in the present application to trace metals is about 10 times that of the P-type wafer in the related art; and under the action of the internal electric field of the PN junction, trace metals are more easily adsorbed into the N-type conductive area 120. For example, Figure 1 As shown, the N-type conductive region 120 in the wafer is a ring-shaped region whose center coincides with the center of the wafer.
[0060] In one example, the potential difference of the electric field generated by the P-type conductive region 110 and the N-type conductive region 120 in the wafer is greater than 0.26V (i.e., the potential difference of the internal electric field of the PN junction is greater than 0.26V). For example, nickel is a common trace metal in a wet etching solution. When the wafer is placed in a wet etching solution for wet etching, silicon atoms react to generate silicon ions and an electron, and the nickel ions in the wet etching solution can react with the electrons to generate nickel atoms, and the standard reduction potential of nickel is -0.26V. By making the potential difference of the electric field generated by the P-type conductive region 110 and the N-type conductive region 120 in the wafer greater than 0.26V, it is possible to provide power for the reduction of nickel, thereby enhancing the wafer's ability to adsorb nickel.
[0061] In one example, the potential difference of the electric field generated by the P-type conductive type region 110 and the N-type conductive type region 120 in the wafer is greater than or equal to 0.3V and less than or equal to 0.5V. For example, the potential difference of the electric field generated by the P-type conductive type region 110 and the N-type conductive type region 120 in the wafer can be 0.3V, 0.35V, 0.4V, 0.45V or 0.5V. By making the potential difference of the electric field generated by the P-type conductive type region 110 and the N-type conductive type region 120 in the wafer within the above range, the adsorption capacity of the wafer for most trace metals can be enhanced. For example, taking the trace metal copper in the wet etching solution as an example, the standard reduction potential of copper is -0.37V, then the potential difference of the electric field generated by the P-type conductive type region 110 and the N-type conductive type region 120 in the wafer can be greater than 0.37V to provide power for the reduction of copper, thereby enhancing the adsorption capacity of the wafer for copper.
[0062] In one example, the potential difference of the electric field generated by the P-type conductive region 110 and the N-type conductive region 120 in the wafer is calculated by the following formula:
[0063]
[0064] Wherein, E0 represents the potential difference of the electric field generated by the P-type conductive region 110 and the N-type conductive region 120, V T Represents thermal voltage, N D represents the donor impurity concentration, N A represents the acceptor magazine concentration, n i represents the intrinsic carrier concentration. For example, n i Equal to 1E10, N D Equal to 2E14, N A Equal to 8E14, it is calculated that E0 is greater than or equal to 0.3V and less than or equal to 0.5V.
[0065] The description of the key steps of the wafer manufacturing method of the present application has been completed. The complete wafer manufacturing method may also include other steps, which will not be described one by one here.
[0066] In summary, the wafer manufacturing method of the embodiment of the present application can form a wafer including a P-type conductivity type region and an N-type conductivity type region. The P-type conductivity type region and the N-type conductivity type region in the wafer form a PN junction, which can enhance the wafer's ability to adsorb trace metals in the wet etching solution, thereby improving the sensitivity and accuracy of detecting trace metals in the wet etching solution.
[0067] Another embodiment of the present application further provides a wafer, which is used to detect trace metals in a wet etching solution, and the wafer is manufactured using the aforementioned manufacturing method.
[0068] The wafer of the embodiment of the present application is manufactured using the aforementioned manufacturing method, and can form a wafer including a P-type conductivity type region and an N-type conductivity type region. The P-type conductivity type region and the N-type conductivity type region in the wafer form a PN junction, which can enhance the wafer's ability to adsorb trace metals in a wet etching solution, thereby improving the sensitivity and accuracy of detecting trace metals in the wet etching solution.
[0069] Another embodiment of the present application also provides a method for detecting trace metals in a wet etching solution. Figures 4 to 7 The method for detecting trace metals in wet etching solution of the present application is described in detail, wherein: Figure 4 A flow chart of a method for detecting trace metals in a wet etching solution according to an exemplary embodiment of the present application is shown. Figure 5 The resistivity, oxygen content and minority carrier lifetime distribution diagram of the sample A wafer according to an exemplary embodiment of the present application are shown. Figure 6 The resistivity, oxygen content and minority carrier lifetime distribution diagram of the sample B wafer according to an exemplary embodiment of the present application are shown. Figure 7 A comparison chart of nickel metal content obtained by inductively coupled plasma mass spectrometry detection of sample A wafer and sample B wafer according to an exemplary embodiment of the present application is shown.
[0070] For example, Figure 4 As shown, the method for detecting trace metals in a wet etching solution in the present application comprises the following steps:
[0071] First, step S41 is performed to provide a wafer manufactured by the manufacturing method of the above embodiment, or to provide a wafer of the above embodiment. Exemplarily, the wafer includes a P-type conductive region and an N-type conductive region.
[0072] Next, step S42 is performed to place the wafer in a wet etching solution for a wet etching process. Exemplarily, the wafer includes a P-type conductive area and an N-type conductive area, and the P-type conductive area and the N-type conductive area in the wafer form a PN junction, which can enhance the wafer's ability to adsorb trace metals in the wet etching solution.
[0073] Next, step S43 is performed, after etching is completed, the wafer is inspected, and when trace metal is detected in the wafer, it is determined that trace metal exists in the wet etching solution. Exemplarily, after etching is completed and before the wafer is inspected, the steps of polishing and cleaning the wafer are also included.
[0074] In one example, the wafer is detected, including: detecting the minority carriers life time (MCLT) of the N-type conductive type region and the P-type conductive type region in the wafer, and when the minority carrier life time of the detected N-type conductive type region is lower than the minority carrier life time of the P-type conductive type region, it is determined that there is trace metal in the wafer. Exemplarily, when there is trace metal in the wet etching solution, due to the presence of the PN junction, the trace metal is more easily adsorbed into the N-type conductive type region, so that the trace metal adsorbed in the N-type conductive type region is more than the trace metal adsorbed in the P-type conductive type region, and the minority carrier life time in the P-type conductive type region and the N-type conductive type region will decrease with the increase of the trace metal adsorbed in the region, therefore, when the minority carrier life time of the detected N-type conductive type region is lower than the minority carrier life time of the P-type conductive type region, it can be determined that there is trace metal in the wafer, and then it can be determined that there is trace metal in the wet etching solution. For example, the photoconductivity attenuation method may be used to measure the minority carrier lifetimes of the N-type conductivity region and the P-type conductivity region in the wafer.
[0075] In one example, the wafer is tested, including: heat treating the wafer; collecting substances on the surface of the wafer by a vapor deposition tool to obtain a collected sample; performing inductively coupled plasma mass spectrometry on the collected sample, and when trace metals are detected, determining that there are trace metals in the wafer. Exemplarily, when there are trace metals in the wafer, heat treating the wafer can drive the trace metals to the surface; in this way, the trace metals on the surface of the wafer can be collected by a vapor deposition tool, and then inductively coupled plasma mass spectrometry can be performed to detect the type and content of the trace metals, and then the presence of trace metals in the wet etching solution can be determined. Exemplarily, heat treating the wafer includes performing medium temperature diffusion (MTOD, Medium Temperature Of Diffuse) treatment on the wafer, and specifically, the wafer can be heat treated at a temperature below 700°C.
[0076] In one example, a sample A wafer and a sample B wafer are provided, both of which have been wet-etched in a wet etching solution, the sample A wafer includes an N-type conductivity type region and a P-type conductivity type region, and the sample B wafer only includes a P-type conductivity type region. Among them, the sample A wafer is obtained by processing the sample A crystal rod of P-type conductivity, and the sample B wafer is obtained by processing the sample B crystal rod of P-type conductivity. In the process of growing the sample A crystal rod by the direct pulling method, the resistivity of the sample A crystal rod is greater than 17ohm·cm, the oxygen content is 10ppma, and the pulling speed is 0.3cm / min-0.7cm / min, so that during the cooling process of the sample A crystal rod, the N-type conductivity type region is generated in the sample A crystal rod due to the influence of the thermal donor defects; and in the process of growing the sample B crystal rod by the direct pulling method, the resistivity of the sample B crystal rod is 7ohm·cm, the oxygen content is 10ppma, and the pulling speed is 0.5cm / min-1cm / min. During the cooling process of the sample B crystal rod, no N-type conductivity type region is formed in the sample B crystal rod.
[0077] In one example, if Figure 5 and Figure 6 As shown, the resistivity of sample A wafer and sample B wafer were detected respectively. The resistivity of the N-type conductive type region in sample A wafer was significantly higher than that of the P-type conductive type region, while the resistivity in sample B wafer had no significant change.
[0078] In one example, if Figure 5 and Figure 6 As shown, the oxygen content of sample A wafer and sample B wafer was detected respectively. The oxygen content at different positions in sample A wafer had obvious changes. For example, the oxygen content near the N-type conductive type area had obvious fluctuations, while the oxygen content in sample B wafer had no obvious change.
[0079] In one example, if Figure 5 and Figure 6 As shown in the figure, when there is a trace amount of metal in the wet etching solution, the minority carrier lifetimes of sample A wafer and sample B wafer are detected respectively. There is an obvious ring distribution in sample A wafer (i.e., a ring-shaped N-type conductive type area), and the minority carrier lifetime in the N-type conductive type area is significantly lower than that in the P-type conductive type area; while the minority carrier lifetime in sample B wafer has no obvious change. Among them, Figure 5 and Figure 6 The colors of different areas in the graph represent the minority carrier lifetime in that area.
[0080] In one example, if Figure 7As shown, taking the presence of nickel metal in the wet etching solution as an example, heat treatment is performed on sample A wafer and sample B wafer respectively, and the substances on the surfaces of sample A wafer and sample B wafer are collected by a vapor deposition tool to obtain collected samples of sample A wafer and sample B wafer, and then inductively coupled plasma mass spectrometry is performed on the collected samples of sample A wafer and sample B wafer to obtain the collected samples of sample A wafer and sample B wafer. Figure 7 It can be seen that the nickel content detected in sample A wafer is significantly higher than that in sample B wafer, that is, the adsorption capacity of sample A wafer to nickel is much stronger than that of sample B wafer to nickel. Figure 7 The vertical axis in the figure represents the gradual increase of Ni metal content from bottom to top.
[0081] The key steps of the method for detecting trace metals in a wet etching solution of the present application have been described so far. The complete method for detecting trace metals in a wet etching solution may also include other steps, which will not be described one by one here.
[0082] In summary, the method for detecting trace metals in a wet etching solution of an embodiment of the present application detects a wafer including a P-type conductivity type region and an N-type conductivity type region manufactured by the manufacturing method of the aforementioned embodiment. The P-type conductivity type region and the N-type conductivity type region in the wafer form a PN junction, which can enhance the wafer's ability to adsorb trace metals in the wet etching solution, thereby improving the sensitivity and accuracy of detecting trace metals in the wet etching solution.
[0083] Although multiple embodiments are described herein, it should be understood that a variety of other modifications and embodiments may be conceived by those skilled in the art, all of which will fall within the spirit and scope of the concepts disclosed herein. More particularly, various modifications and changes may be made to the arrangements and / or components of the combined arrangements of the subject matter within the scope of the disclosure, drawings, and appended claims of the present application. In addition to modifications and changes to the components and / or arrangements, the use of alternatives is also an obvious option for those skilled in the art.
Claims
1. A method for manufacturing a wafer, wherein the wafer is used to detect trace metals in a wet etching solution, characterized in that: The method comprises: Growing a P-type conductive type crystal rod by a Czochralski method, wherein, during the cooling process of the crystal rod, a region of N-type conductive type is formed in the crystal rod under the influence of heated donor defects; The crystal rod is processed to obtain a wafer, wherein the wafer includes a P-type conductive region and an N-type conductive region.
2. The manufacturing method according to claim 1, characterized in that: In the process of growing the crystal rod by using the Czochralski method, the resistivity of the crystal rod is greater than or equal to 10 ohm·cm and less than or equal to 500 ohm·cm.
3. The manufacturing method according to claim 2, characterized in that: In the process of growing the crystal rod by using the Czochralski method, the oxygen content of the crystal rod is greater than or equal to 10 ppma and less than or equal to 20 ppma.
4. The manufacturing method according to claim 3, characterized in that: In the process of growing the crystal rod by using the Czochralski method, the pulling speed of the crystal rod is greater than or equal to 0.3 cm / min and less than or equal to 1 cm / min.
5. The manufacturing method according to claim 1, characterized in that: The potential difference of the electric field generated by the P-type conductive region and the N-type conductive region in the wafer is greater than or equal to 0.3V and less than or equal to 0.5V.
6. The manufacturing method according to claim 1, characterized in that: The N-type conductive area in the wafer is a ring-shaped area whose center coincides with the center of the wafer.
7. A wafer for detecting trace metals in a wet etching solution, characterized in that: The wafer is manufactured by the manufacturing method described in any one of claims 1 to 6.
8. A method for detecting trace metals in a wet etching solution, characterized in that: The method comprises: Providing a wafer manufactured by the manufacturing method according to any one of claims 1 to 6, or providing a wafer according to claim 7; Placing the wafer into a wet etching solution to perform a wet etching process; After etching is completed, the wafer is inspected, and when trace metal is detected in the wafer, it is determined that trace metal exists in the wet etching solution.
9. The method according to claim 8, characterized in that Testing the wafer includes: The minority carrier lifetimes of the N-type conductivity region and the P-type conductivity region in the wafer are detected, and when the detected minority carrier lifetime of the N-type conductivity region is lower than the minority carrier lifetime of the P-type conductivity region, it is determined that trace metal exists in the wafer.
10. The method according to claim 8, characterized in that Testing the wafer includes: performing heat treatment on the wafer; Collecting the material on the surface of the wafer by a vapor deposition tool to obtain a collected sample; The collected samples are subjected to inductively coupled plasma mass spectrometry detection, and when trace metals are detected, it is determined that the trace metals exist in the wafer.