Wafer pollution element detection method

Abstract

The invention provides a wafer pollution element detection method, and relates to the technical field of semiconductors. The wafer pollution element detection method comprises detection of pollution elements in a target wafer; an oxidation step: oxidizing a surface layer with a preset thickness of the target wafer into an oxide layer; a release step: dissolving the oxide layer by using a dissolving substance in an aerosol state to form a to-be-detected solution; and a detection step: dividing the target wafer into a plurality of detection areas, and detecting the content of pollution elements in the to-be-detected liquid in each detection area. According to the detection method, the position distribution of the pollution elements can be fixedly released, and the wafer is subjected to partitioned detection in the detection step, so that the content of the pollution elements in each detection region is obtained, the causes of the pollution of the elements are conveniently and accurately judged accordingly, the source tracing of the causes of the pollution of the elements is realized, and the detection efficiency is improved. Therefore, element pollution is effectively controlled and improved, and the purity of subsequent wafers and the performance and reliability of semiconductor devices obtained through processing of the wafers are ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to a wafer pollution element detection method. BACKGROUND

[0002] Wafer itself or in the process, may introduce element pollution, in which, metal element pollution on the performance and reliability of the final device is particularly serious. With the rapid development of semiconductor, photovoltaic, display panel and other high-tech industries, the purity of wafer material is more and more high, and the control of element pollution is more and more strict, so it is very important to accurately detect the pollution elements in the wafer and trace the causes.

[0003] In recent years, VPD-ICP-MS technology gradually becomes the mainstream method of element detection because of its high sensitivity, low detection limit and wide dynamic range. In related technology, the wafer is generally detected locally or as a whole, and only whether there is element pollution in the wafer can be detected, but the causes of element pollution cannot be traced according to the element pollution, so that the control and improvement of element pollution is difficult. SUMMARY

[0004] The purpose of the present application is to provide a wafer pollution element detection method to solve the technical problem that in related technology, only whether there is element pollution in the wafer can be detected, but the causes of element pollution cannot be traced according to the element pollution, so that the control and improvement of element pollution is difficult.

[0005] To solve the above problems, the present application provides a wafer pollution element detection method, which comprises the detection of internal pollution elements of a target wafer.

[0006] Oxidation step: oxidizing the surface layer of the target wafer with a predetermined thickness into an oxide layer;

[0007] Release step: dissolving the oxide layer with a dissolved substance in aerosol state to form a to-be-tested liquid;

[0008] Detection step: dividing the target wafer into a plurality of detection zones, and detecting the content of pollution elements in the to-be-tested liquid in each detection zone.

[0009] Optionally, the dissolved substance comprises hydrofluoric acid, hydrochloric acid and nitric acid.

[0010] Optionally, in the oxidation step, ozone and an adsorbing liquid in aerosol state are introduced into the process chamber.

[0011] Optionally, the adsorbing liquid comprises hydrogen peroxide solution with a content of 31% to 38%.

[0012] Optionally, in the oxidizing step, the inert gas is continuously introduced into the process chamber after the inert atmosphere is formed by introducing the inert gas into the process chamber, and then the ozone and the adsorbed liquid in the aerosol state are introduced into the process chamber.

[0013] Optionally, in the detecting step of the target wafer internal contaminant element, the oxidizing step is followed by:

[0014] The temperature decreasing step: decreasing the temperature of the target wafer to 16-18℃.

[0015] Optionally, in the detecting step of the target wafer internal contaminant element, the oxidizing step, the releasing step and the detecting step are cyclically performed until the content of the contaminant element detected in the detecting step is less than the preset content threshold.

[0016] Optionally, in the detecting step of the target wafer internal contaminant element, the oxidizing step is followed by:

[0017] The measuring step: measuring the uniformity of the thickness of the oxide layer formed in the oxidizing step.

[0018] Optionally, the detecting method further comprises detecting the surface contaminant element of the target wafer.

[0019] Optionally, the target wafer comprises a wafer that has not been processed and a wafer that has been processed by a preset process.

[0020] The detecting method of the wafer contaminant element provided by the present application can realize the fixed position distribution releasing of the contaminant element by oxidizing the surface layer of the target wafer into an oxide layer, then adhering and reacting and dissolving the dissolving substance in the aerosol state to the oxide layer, and the flowability of the dissolving substance and the to-be-detected liquid formed in the process of adhering and reacting and dissolving is small, and the position distribution of the contaminant element released from the oxide layer into the to-be-detected liquid is approximately stationary. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to make the technical solutions in the specific embodiments or related art of the present application clearer, the accompanying drawings needed in the specific embodiments or related art description will be briefly introduced. Obviously, the accompanying drawings in the following description are some embodiments of the present application, and all other embodiments obtained by a person of ordinary skill in the art without any creative effort based on the embodiments in the present application shall fall within the protection scope of the present application.

[0022] Figure 1 A first flowchart of a wafer contamination element detection method according to an embodiment of the present application;

[0023] Figure 2 A second flowchart of a wafer contamination element detection method according to an embodiment of the present application;

[0024] Figure 3 A third flowchart of a wafer contamination element detection method according to an embodiment of the present application;

[0025] Figure 4a A schematic diagram of detecting the content of Li contamination elements in the interior of a pre-wafer not subjected to process treatment according to the wafer contamination element detection method provided by an embodiment of the present application;

[0026] Figure 4b A schematic diagram of detecting the content of Na contamination elements in the interior of a pre-wafer not subjected to process treatment according to the wafer contamination element detection method provided by an embodiment of the present application;

[0027] Figure 5a A schematic diagram of detecting the content of Li contamination elements in the interior of a post-wafer subjected to a preset process treatment according to the wafer contamination element detection method provided by an embodiment of the present application;

[0028] Figure 5b A schematic diagram of detecting the content of Na contamination elements in the interior of a post-wafer subjected to a preset process treatment according to the wafer contamination element detection method provided by an embodiment of the present application. DETAILED DESCRIPTION

[0029] The technical solutions of the present application will be described clearly and completely below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without any creative effort shall fall within the protection scope of the present application.

[0030] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0031] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0032] In the related technology of detecting the contaminant elements in the wafer by VPD-ICP-MS technology, generally includes an oxide film forming process and a recovery detection process, wherein in the oxide film forming process, the wafer surface is oxidized to form an oxide film; in the recovery detection process, a liquid dissolving solution is covered on the surface of the oxide film to dissolve the entire oxide film to obtain a test solution, and the contaminant elements existing in the oxide film are released into the test solution, wherein the dissolving solution has high flowability during the process of being transported to the surface of the oxide film and reacting with the oxide film, so that the contaminant elements released into the test solution also change positions with the flow of the dissolving solution and the test solution; through the recovery detection of the test solution, it can only be determined whether the wafer has element contamination, but cannot trace the causes according to the element contamination, so that the related processes causing the element contamination cannot be effectively controlled and improved, resulting in that the control and improvement of the element contamination are difficult.

[0033] The present embodiment provides a method for detecting contaminant elements in a wafer, which realizes the fixed release of the position distribution of the contaminant elements by using the aerosol state of the dissolving substance to adhere to the oxide layer and react and dissolve it, so that the position distribution of the contaminant elements released into the test solution in the oxide layer is approximately stationary; then the test solution is detected in zones to obtain the content of the contaminant elements in each detection zone, and according to the position distribution and content distribution of the contaminant elements, the causes can be accurately and conveniently traced, the related processes causing the element contamination can be effectively controlled and improved to realize the effective control and improvement of the element contamination, and then the purity of the wafer and the performance and reliability of the semiconductor device processed therefrom are ensured. The method for detecting contaminant elements in a wafer provided by the present embodiment will be described in detail below with reference to the drawings.

[0034] Figure 1 A first flowchart of a method for detecting a contaminant element in a wafer according to an embodiment of the present application. The contaminant element in the wafer directly affects the purity and performance of the wafer, such as Figure 1 As shown in the figure, the method includes detecting the contaminant element in the wafer:

[0035] S102 Oxidation step: oxidizing a preset thickness of the surface layer of the wafer to form an oxide layer.

[0036] The wafer to be detected for the contaminant element is taken as the wafer, and the surface layer of the wafer is oxidized to form an oxide layer of SiO2, wherein when the contaminant element exists in the surface layer of Si, the contaminant element enters the oxide layer of SiO2, and the position distribution and content of the contaminant element remain unchanged. The preset thickness can be 100-140 angstroms.

[0037] S104 Release step: dissolving the oxide layer with a dissolving material in aerosol state to form a to-be-detected liquid.

[0038] The dissolving liquid capable of reacting with the oxide layer of SiO2 is dispersed in a gaseous medium in the form of liquid particles to form a dissolving material in aerosol state, which can be attached to the surface of the oxide layer of SiO2 and react with it to dissolve it when sprayed onto the surface of the oxide layer of SiO2, and the reaction product is the to-be-detected liquid; when the contaminant element exists in the oxide layer of SiO2, the contaminant element is released into the to-be-detected liquid in the corresponding area, and the flowability of the to-be-detected liquid is small, and accordingly, the position distribution of the contaminant element released into the to-be-detected liquid is approximately stationary, thereby realizing the fixed release of the position distribution of the contaminant element. The contaminant element can include metal elements such as Li, Na, Pt, Au, and Ag.

[0039] S106 Detection step: dividing the wafer into a plurality of detection zones, and detecting the content of the contaminant element in the to-be-detected liquid in each detection zone.

[0040] After the contaminant elements in the surface layer of the target wafer with a preset thickness are released into the to-be-tested liquid, the area where the target wafer is located is divided, specifically divided into not less than 4 detection zones; then the to-be-tested liquid in each detection zone is independently detected to measure the content of the contaminant elements therein, so as to obtain the content of the contaminant elements in each detection zone, and accordingly obtain the position distribution and content distribution of the contaminant elements in the surface layer of the target wafer with a preset thickness; then, according to the type of the target wafer and the process treatment procedure thereof, the cause of the element pollution can be conveniently and more accurately judged to realize the traceability of the cause of the element pollution, and the related components and process parameters of the process treatment procedure are adjusted and controlled accordingly, so as to realize effective control and improvement of the element pollution, and ensure the purity of the subsequent wafer and the performance and reliability of the semiconductor device processed from the wafer.

[0041] Specifically, in the detecting step, the target wafer can be divided into a center circle located at a center position and a plurality of concentric circles coaxial with the center circle, and the center circle and each concentric circle are divided into a plurality of equal parts along the circumferential direction, so as to obtain a plurality of detection zones. Figure 4a and Figure 4b As shown in the figures, the target wafer is divided into a center circle located at a center position and 6 concentric circles coaxial with the center circle, and the center circle and the 6 concentric circles are divided into four detection zones along the circumferential direction through two mutually perpendicular diameters, so as to obtain a total of 28 detection zones; specifically, when the radius of the target wafer is 150 mm, the radius of the center circle can be 40 mm, and along the direction away from the center circle, the radius ranges of the concentric circles are 40-60 mm, 60-80 mm, 80-100 mm, 100-120 mm, 120-140 mm and 140-150 mm, respectively.

[0042] Then, the wafer contaminant element detection method provided by the embodiment of the present application can realize fixed release of the position distribution of the contaminant elements after the surface layer of the target wafer is oxidized into an oxidation layer, and the dissolving material in the aerosol state is attached to the oxidation layer and reacts and dissolves, and in the process of attachment and reaction and dissolution, the flowability of the dissolving material and the to-be-tested liquid formed is small, and the position distribution of the contaminant elements released into the to-be-tested liquid in the oxidation layer is approximately stationary; in the detecting step, the wafer is detected in a partitioned manner, so as to obtain the content of the contaminant elements in each detection zone, and according to the position distribution and content distribution of the contaminant elements and the type of the target wafer and the process treatment procedure thereof, the cause of the element pollution can be conveniently and more accurately judged to realize the traceability of the cause of the element pollution, and the wafer source, the related components and process parameters of the process treatment procedure are adjusted and controlled accordingly, so as to realize effective control and improvement of the element pollution, and ensure the purity of the subsequent wafer and the performance and reliability of the semiconductor device processed from the wafer.

[0043] In the embodiment of the present application, the target wafer includes a wafer not subjected to process treatment and a wafer subjected to preset process treatment. The wafer not subjected to process treatment is a front wafer, and the wafer subjected to preset process treatment is a rear wafer. The front wafer and the rear wafer of the same batch can be sequentially taken as the target wafer to detect the internal contaminant elements. When the contaminant elements exist in the front wafer, it is indicated that the contaminant elements have been introduced in the manufacturing process of the wafer, and the manufacturing process should be controlled and improved. When the contaminant elements exist in the rear wafer, it is indicated that the related components or process parameters of the corresponding preset process treatment procedure have problems, and the related components and process parameters of the preset process treatment procedure should be adjusted and controlled. When the performance and reliability of the device processed from the wafer have problems, the front wafer and the rear wafer of the same batch of the wafer are comprehensively detected, and the source of the contaminant elements can be traced back comprehensively and effectively.

[0044] In the embodiment of the present application, the dissolving substance includes hydrofluoric acid, hydrochloric acid and nitric acid. The dissolving liquid formed by mixing the hydrofluoric acid, the hydrochloric acid and the nitric acid is in a liquid particle dispersed in a gaseous medium to form an aerosol state dissolving substance. The corrosiveness of the hydrofluoric acid, the hydrochloric acid and the nitric acid is different, and the releasing ability of the contaminant elements is different. The releasing ability of the contaminant elements can be significantly enhanced after mixing the hydrochloric acid and the nitric acid. In the process of reacting the dissolving substance with the SiO2 oxide layer, the releasing intensity of the same contaminant element can be effectively improved, the recovery rate of the same contaminant element and the detection accuracy of the content of the same contaminant element can be improved, and the releasing range of different types of contaminant elements can be increased. For example, Au or Pt which is insoluble in hydrofluoric acid can be dissolved in the mixture of the hydrochloric acid and the nitric acid to be released. Therefore, the detection accuracy of the position distribution and the content distribution of the contaminant elements can be improved, and the source of the contaminant elements can be traced back conveniently and accurately.

[0045] In the embodiment of the present application, in the oxidation step, the ozone and the adsorbing liquid in the aerosol state are introduced into the process chamber. In the oxidation step, the target wafer is sent into the process chamber, and then the ozone O3 is introduced into the process chamber. The O3 is a gaseous medium, and the adsorbing liquid in the aerosol state is dispersed in the O3. The adsorbing liquid in the aerosol state contacts and adheres to the surface of the target wafer to form a liquid adsorption layer. The liquid adsorption layer can adsorb the O3 to increase the contact area and the contact strength of the O3 and the Si surface layer, thereby improving the reaction efficiency of the O3 and the Si to generate the SiO2 oxide layer. In addition, the oxidation reaction of the O3 and the Si is an exothermic reaction. The adsorbing liquid in the aerosol state and the liquid adsorption layer adhered to the surface of the target wafer can absorb heat to effectively control the chamber temperature of the process chamber and ensure the stability and safety of the process.

[0046] Specifically, the process chamber can be a VPD (Vapor Phase Decomposition) chamber.

[0047] In the embodiment of the present application, the adsorption liquid comprises hydrogen peroxide solution with a content of 31% to 38%. The solution formed by mixing water as a solvent and hydrogen peroxide as a solute is used as the adsorption liquid, wherein the mass fraction of hydrogen peroxide is 31% to 38%, preferably 35%. In addition to the above-mentioned functions of adsorbing O3 and absorbing reaction heat, the hydrogen peroxide solution also has the function of enhancing the oxidation ability of O3, so as to further improve the oxidation effect of O3 on Si and improve the generation efficiency of the SiO2 oxide layer. In addition, the hydrogen peroxide solution can be self-decomposed into water and oxygen in the subsequent process, without causing pollution to the target wafer and the generated oxide layer, and without the need for cleaning operation, thereby improving the detection accuracy and convenience of the pollution elements.

[0048] Of course, in other embodiments, in addition to the above-mentioned hydrogen peroxide solution, water, hydrochloric acid solution or nitric acid solution can also be selected.

[0049] In the embodiment of the present application, in the oxidation step, the inert gas is continuously introduced into the process chamber when the inert gas is introduced into the process chamber to form an inert atmosphere and then the adsorption liquid in the aerosol state is introduced into the process chamber. In the oxidation step, the target wafer is sent into the process chamber, and then the inert gas is first introduced into the process chamber to drive out the air in the process chamber, so that the process chamber is in an inert atmosphere. Then, O3 and the adsorption liquid in the aerosol state are introduced into the process chamber, and the inert gas is continuously introduced to dilute O3, reduce the reaction intensity of O3 and Si, and improve the detection stability and safety of the pollution elements.

[0050] Specifically, the inert gas can be selected from N2, Ar and He. The oxidation thickness of the surface layer of the target wafer can be determined by controlling the flow rates of O3, the inert gas and the hydrogen peroxide solution in the aerosol state, and the reaction time.

[0051] In the embodiment of the present application, before the oxidation step in the detection step of the pollution elements inside the target wafer, the temperature of the target wafer is reduced to 16℃ to 18℃. Specifically, before the target wafer is conveyed to the process chamber, the temperature of the target wafer is first reduced to 16℃ to 18℃ in the temperature reduction step. Then, the target wafer is conveyed to the process chamber and the oxidation step is continued, so as to reduce the reaction temperature of the target wafer and O3, and improve the reaction efficiency and safety of the target wafer and O3. Specifically, the Foup containing the target wafer can be conveyed to the nitrogen cabinet at 16℃ to 18℃ for at least 1 hour, so as to reduce the temperature of the target wafer to 16℃ to 18℃.

[0052] Specifically, after the oxidation step, the release step and the detection step can be as follows:

[0053] Release step: The oxidized target wafer is transferred to the process chamber, and an aerosol of hydrofluoric acid, hydrochloric acid and nitric acid is introduced to dissolve the SiO2 oxide layer and obtain the test solution; nitrogen is introduced into the process chamber to purge the remaining dissolved aerosol, and then the target wafer is transferred out of the process chamber and transferred to the stage.

[0054] Inspection step: The wafer is divided into the following sections using software: Figure 4a and 4b The 28 detection zones shown are used to collect contaminant elements in each zone by using a scanning head containing 1 ml of elemental scanning solution (a mixture of 4% hydrogen peroxide and 3% hydrofluoric acid). The volume of the scanning solution is measured to determine the recovery rate. The scanning solution is then poured into an ICP-MS for testing. Based on the test results, the content of contaminant elements in each detection zone of the target wafer is obtained.

[0055] In this embodiment of the invention, the detection step of contaminant elements inside the target wafer is performed by cyclically executing the oxidation step, the release step, and the detection step until the content of contaminant elements measured in the detection step is less than a preset content threshold. In the detection steps for contaminant elements inside the target wafer, each oxidation step, release step, and detection step constitutes a detection cycle, capable of detecting the content of contaminant elements in a Si layer of a corresponding preset thickness. Specifically, the first detection cycle is executed, starting with the oxidation step: oxidizing the Si surface layer of the target wafer to a SiO2 oxide layer of the first preset thickness, where contaminant elements reside. Then, the release step is executed: an aerosol-like dissolved substance reacts with the SiO2 oxide layer, dissolving it to form a test solution, releasing the contaminant elements within the SiO2 oxide layer. The content of contaminant elements in the test solution is then the content of contaminant elements in the Si surface layer of the first preset thickness. Finally, the detection step is executed: the target wafer is divided into multiple detection areas, and the content of contaminant elements in the test solution of each area is detected separately. This yields the content of contaminant elements in the Si surface layer of the first preset thickness in each detection area. When the content of contaminant elements in any detection area is greater than or equal to a preset content threshold, it indicates that the Si surface layer of the first preset thickness contains contaminant elements.

[0056] The second detection cycle is continuously executed to perform an oxidation step of oxidizing a second preset thickness of the Si surface layer of the target wafer into a SiO2oxidation layer, and the contaminant elements in the Si surface layer are located in the SiO2oxidation layer; then the releasing step and the detecting step are sequentially performed to obtain the content of the contaminant elements in the second preset thickness of the Si surface layer in each detection area, and when the content of the contaminant elements in each detection area is greater than or equal to the preset content threshold, it is indicated that the second preset thickness of the Si surface layer contains the contaminant elements. Such a cycle is repeated until the Nth detection cycle is performed to obtain the content of the contaminant elements in the Nth preset thickness of the Si surface layer in each detection area, and the content of the contaminant elements in each detection area is less than the preset content threshold, indicating that the content of the contaminant elements in the Nth preset thickness of the Si surface layer is small and can be ignored, and the detection of the contaminant elements in the target wafer is completed.

[0057] Through the above detection cycle, the content of the contaminant elements in each detection area in each preset thickness of the Si layer containing the contaminant elements along the depth direction of the target wafer can be obtained, so that not only the content of the contaminant elements in each detection area can be measured, but also the contamination depth of the contaminant elements in each detection area can be measured. The causes of the element contamination can be traced according to the position distribution, content distribution and contamination depth of the contaminant elements, the tracing accuracy and convenience are further improved, and the related components and process parameters for generating the element contamination can be more accurately adjusted and controlled, so that the effective control and improvement of the element contamination are further improved. In addition, when the target wafer is a wafer that has not been processed, the contamination of the contaminant elements can be accurately fed back to the wafer source, so as to facilitate the repair operation of the wafer.

[0058] Specifically, the preset content threshold can be 10 8 atoms / cm 2 .

[0059] In the embodiment of the present application, after the oxidation step in the detection step of the internal contaminant element of the target wafer, the measurement step of measuring the uniformity of the thickness of the oxide layer formed in the oxidation step is included. In the detection step of the internal contaminant element of the target wafer, the measurement step is arranged between the oxidation step and the dissolution step. After the target wafer is oxidized into the SiO2 oxide layer from the Si surface layer with a preset thickness in the oxidation step, the measurement step is continued to measure the overall thickness uniformity of the SiO2 oxide layer. Specifically, the thickness of multiple points of the SiO2 oxide layer can be detected, and the thickness standard deviation of the SiO2 oxide layer is calculated. When the obtained thickness standard deviation is less than the preset standard deviation threshold, it indicates that the overall thickness uniformity of the SiO2 oxide layer is high, the depth corresponding to the content of the contaminant element in each detection area measured in the subsequent detection step is accurate, the detection accuracy is high, and the traceability of the element contamination is more accurate and reliable. When the obtained thickness standard deviation is greater than or equal to the preset standard deviation threshold, it indicates that the overall thickness uniformity of the SiO2 oxide layer is low, the accuracy of the depth corresponding to the content of the contaminant element in each detection area measured in the subsequent detection step is low, the detection accuracy is low, and the traceability of the element contamination is poor.

[0060] Specifically, the KAL film thickness tester can be used to measure the uniformity of the thickness of the oxide layer.

[0061] In the embodiment of the present application, the detection method further includes the detection of the surface contaminant element of the target wafer. In addition to the detection of the internal contaminant element of the target wafer described above, the surface contaminant element of the target wafer can also be detected to determine whether the surface of the target wafer contains contaminant elements, so as to further improve the detection comprehensiveness of the situation that the contaminant elements contaminate the target wafer, and correspondingly further improve the traceability of the element contamination cause. Specifically, when the surface of the new wafer contains contaminant elements, the storage and transportation conditions thereof can be controlled and improved, or a cleaning step can be added to clean the surface contaminant elements, so as to ensure the purity of the front wafer. When the surface of the rear wafer contains contaminant elements, the process flow thereof can be controlled and improved, such as adding a cleaning step to clean the surface element contamination, so as to ensure the purity of the rear wafer.

[0062] Figure 2 A second flowchart of the wafer contaminant element detection method according to the embodiment of the present application is shown in FIG. 2. As shown in FIG. 2, the detection method includes the detection of the internal contaminant element of the target wafer. Figure 2

[0063] S201 cooling step: the temperature of the target wafer is reduced to 16-18℃.

[0064] S202 oxidation step: the surface layer of the target wafer with a preset thickness is oxidized into an oxide layer.

[0065] S203 measurement step: the thickness uniformity of the oxide layer is measured.​

[0066] S204 Release Step: The oxide layer is dissolved using aerosol-state dissolved substances to form the test solution.

[0067] S205: Detection step: Divide the target wafer into multiple detection areas and detect the content of contaminant elements in the test solution located in each detection area.

[0068] S206: Determine whether the content of pollutant elements in the test liquid in each detection zone is less than the preset content threshold; if yes, end the detection; if no, continue to step S202.

[0069] Figure 3 This is a schematic diagram of the third process of a method for detecting wafer contamination elements according to an embodiment of the present invention. Figure 3 As shown, the detection method includes:

[0070] S302 testing checks for contaminating elements on the surface of unprocessed pre-wafers in the same batch.

[0071] S304 testing checks for contaminating elements inside pre-processed wafers from the same batch that have not undergone processing.

[0072] S306 tests whether there are contaminating elements on the surface of wafers that have undergone a preset process in the same batch.

[0073] S308 tests whether there are contaminating elements inside the wafers in the same batch that have undergone a preset process.

[0074] For example, in a specific embodiment: during the wafer processing, it was discovered that the wafer contained Li and Na contaminants after a preset process, causing its performance and reliability to fail to meet requirements. Therefore, the cause of the elemental contamination was traced:

[0075] Figure 4a This diagram illustrates the detection of Li contamination content inside an unprocessed wafer using the wafer contamination detection method provided in this embodiment of the invention. The method involves... Figure 4a As shown, after testing, the Li contamination content inside the front wafer was found to be approximately 0, which is less than the preset content threshold of 10. 8 atoms / cm 2 The characterization indicates that the wafer does not contain Li contaminant elements.

[0076] Figure 4b This diagram illustrates the detection of Na contamination content inside an unprocessed wafer using the wafer contamination detection method provided in this embodiment of the invention. Figure 4bAs shown, the content of the Na contamination element in the front wafer is approximately 0, which is less than the preset content threshold 10 8 atoms / cm 2 , indicating that the front wafer does not contain the Na contamination element.

[0077] Figure 5a For the wafer contamination element detection method provided by the embodiment of the present application, a schematic diagram of detecting the content of the Li contamination element in the back wafer after the preset process is shown in FIG. 6. Figure 5a As shown, the Li contamination element is concentrated in the lower left corner and the lower right corner of the back wafer, and the content of the Li contamination element in the four arc-shaped detection areas near the outer edge of the lower left corner is relatively large.

[0078] Figure 5b For the wafer contamination element detection method provided by the embodiment of the present application, a schematic diagram of detecting the content of the Na contamination element in the back wafer after the preset process is shown in FIG. 7. Figure 5b As shown, the Na contamination element is concentrated in an arc-shaped detection area near the outer edge of the lower left corner of the back wafer.

[0079] According to the position distribution and content distribution of the Li contamination element, it is determined that the Li contamination element is mainly introduced by the Li electrode adjacent to the lower left corner region of the target wafer in the preset process. After replacing the Li electrode, the Li contamination element and the Na contamination element in the wafer after the subsequent preset process disappear, thereby realizing convenient and accurate tracing of the causes of the Li contamination element and the Na contamination element, and effectively controlling and improving the Li contamination element and the Na contamination element by replacing the Li electrode, so as to ensure the purity of the subsequent wafer and the performance and reliability of the semiconductor device processed therefrom.

[0080] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for detecting a wafer contamination element, characterized by, The detection method comprises the following steps: An oxidation step: oxidizing a preset thickness of a surface layer of the target wafer into an oxide layer; A releasing step: dissolving the oxide layer into a to-be-detected liquid by using a dissolving substance in an aerosol state; A detecting step: dividing the target wafer into a plurality of detection areas, and detecting the content of the contaminant elements in the to-be-detected liquid in each detection area.

2. The detection method according to claim 1, characterized in that, The dissolving substance comprises hydrofluoric acid, hydrochloric acid and nitric acid.

3. The detection method according to claim 1 or 2, characterized in that, In the oxidation step, ozone and an adsorbing liquid in an aerosol state are introduced into a process chamber.

4. The detection method according to claim 3, characterized in that, The adsorbing liquid comprises a hydrogen peroxide solution with a content of 31% to 38%.

5. The detection method according to claim 3, characterized in that, In the oxidation step, first, an inert gas is introduced into the process chamber to form an inert atmosphere, and then the ozone and the adsorbing liquid in the aerosol state are introduced into the process chamber, and the inert gas is continuously introduced.

6. The method of claim 3, wherein, Before the oxidation step, the detection method further comprises the following steps: A cooling step: reducing the temperature of the target wafer to 16°C to 18°C.

7. The detection method according to claim 1 or 2, characterized by, In the detection step, the oxidation step, the releasing step and the detecting step are cyclically executed until the content of the contaminant elements detected in the detecting step is less than a preset content threshold.

8. The detection method according to claim 1 or 2, characterized by, After the oxidation step, the detection method further comprises the following steps: A measuring step: measuring the uniformity of the thickness of the oxide layer formed in the oxidation step.

9. The detection method according to claim 1 or 2, characterized by, The detection method further comprises detection of the surface contaminant elements of the target wafer.

10. The detection method according to claim 1 or 2, characterized by, The target wafer comprises a wafer that has not undergone a process treatment and a wafer that has undergone a preset process treatment.

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