A method of monitoring an annealing process

Abstract

The application relates to a monitoring method of an annealing process, which comprises the following steps: providing a monitoring wafer, which comprises a first base wafer and a monitoring film layer on the surface of the first base wafer; placing the monitoring wafer in a furnace tube of an annealing device for annealing, wherein the annealing device comprises a quartz component; detecting the pit defect level in the monitoring film layer after annealing, so as to obtain the pollution level of impurity pollution released by the quartz component in the furnace tube during the annealing process; wherein the corrosion rate of the impurity pollution to the monitoring film layer is higher than that to the first base wafer during the annealing process. According to the monitoring method, the impurity pollution released by the quartz component during the annealing process can corrode the monitoring film layer and form pit defects with a larger size, the pit defects are easier to be detected, and therefore the detection precision of the impurity pollution is improved.

Description

Technical Field

[0001] This invention relates to the technical field of semiconductor processing, and more specifically to a method for monitoring an annealing process. Background Technology

[0002] Currently, in the wafer annealing process, the temperature inside the furnace tube can reach 1000℃ or higher during high-temperature heating. Impurities in quartz components such as quartz tubes, such as chlorine, fluorine, and hydroxyl groups, can diffuse under high-temperature conditions, resulting in high-temperature corrosion defects on the wafer surface. Therefore, in order to ensure product quality, the level of impurity contamination inside the furnace tube is monitored during the high-temperature annealing process by using wafer monitoring methods.

[0003] In related technologies, bare silicon wafers are often used as monitoring wafers in high-temperature annealing furnaces to monitor corrosion defects caused by impurity diffusion and process stability. However, because defects caused by impurity diffusion are generally small in size on the wafer surface, usually concentrated within 45nm, it is difficult to effectively monitor corrosion defects caused by the diffusion of impurities released from quartz by using bare silicon wafers as monitoring wafers. Therefore, it is also impossible to effectively monitor the level of impurity contamination during the high-temperature annealing process.

[0004] In view of the above-mentioned technical problems, this application provides a method for monitoring the annealing process. Summary of the Invention

[0005] The summary section introduces a series of simplified concepts, which will be further explained in detail in the detailed description section. The summary section of this invention is not intended to limit the key features and essential technical features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0006] To address the existing problems, this application provides a method for monitoring an annealing process, the method comprising:

[0007] Provide a monitoring wafer, including a first substrate wafer and a monitoring film layer on the surface of the first substrate wafer;

[0008] The monitoring wafer is placed in the furnace tube of an annealing equipment for annealing, the annealing equipment including a quartz component;

[0009] The level of pit defects in the monitoring film layer after annealing is detected to obtain the level of contamination in the furnace tube by impurities released by the quartz component during the annealing process.

[0010] During the annealing process, the corrosion rate of the monitoring film due to impurities is higher than the corrosion rate of the first substrate wafer.

[0011] For example, the monitoring method further includes:

[0012] Before the annealing process, the thickness of the monitoring film layer before annealing is detected;

[0013] The monitoring wafer and the product wafer are placed in the furnace tube of the annealing equipment for annealing. The product wafer includes a second substrate wafer and a product film layer located on the surface of the second substrate wafer. The monitoring film layer and the product film layer are prepared under the same process conditions.

[0014] After the annealing process is completed, the thickness of the monitoring film layer after annealing is detected.

[0015] The degree of change in the density of the product film layer before and after the annealing process is determined based on the thickness before and after the annealing process.

[0016] For example, the monitoring method includes:

[0017] The monitoring wafer and the product wafer are placed in the furnace tube of an annealing apparatus for an annealing process. The product wafer includes a second substrate wafer and a product film layer located on the surface of the second substrate wafer; or, the annealing process forms a product film layer on the surface of the product wafer.

[0018] The corrosion rate of the monitoring film due to the impurity contamination is higher than or equal to the corrosion rate of the product film, and the degree of influence of the impurity contamination on the product film is determined by the contamination level.

[0019] For example, the monitoring method includes:

[0020] The monitoring wafer and the product wafer are placed in the furnace tube of an annealing apparatus for an annealing process. The product wafer includes a second substrate wafer and a product film layer located on the surface of the second substrate wafer; or, the annealing process forms a product film layer on the surface of the product wafer.

[0021] The thickness of the monitoring membrane is greater than the thickness of the product membrane, and the degree of influence of the impurity contamination on the product membrane is determined by the contamination level.

[0022] For example, the thickness of the monitoring film ranges from 10 nm to 800 nm.

[0023] For example, the size of the pit defect is greater than or equal to 300 nm.

[0024] For example, the first substrate wafer includes a silicon wafer.

[0025] For example, the material of the monitoring film includes at least one of the following: silicon oxide, polycrystalline silicon, aluminum oxide, and silicon nitride.

[0026] For example, the monitoring film is deposited using a low-pressure chemical vapor deposition method, a physical vapor deposition method, or an atomic layer deposition method.

[0027] For example, the impurity contamination includes at least one of the following impurities: Cl, F, -OH; and / or

[0028] The annealing temperature range of the annealing process is 950℃~1300℃.

[0029] The annealing process monitoring method in this application involves a monitoring wafer comprising a first substrate wafer and a monitoring film layer on the surface of the first substrate wafer. The monitoring wafer is placed in the furnace tube of an annealing apparatus for annealing. By detecting the level of pit defects in the monitoring film layer after annealing, the contamination level of impurities released by the quartz component during annealing within the furnace tube can be obtained. Therefore, if impurities are present during annealing, their diffusion will corrode the monitoring film layer, thereby forming pit defects in the monitoring film. Since the corrosion rate of impurities on the monitoring film layer is higher than that on the first substrate wafer during annealing, compared to using a silicon wafer as the monitoring wafer, the monitoring method of this application can form larger pit defects in the monitoring film if impurities are present during annealing. This makes the pit defects easier to detect, and the level of pit defects can be used to determine the contamination level of impurities released by the quartz component during annealing within the furnace tube, thus improving the detection accuracy and sensitivity of impurities. Attached Figure Description

[0030] The following drawings, which are incorporated herein by reference as part of this invention, are provided for understanding the invention. The drawings illustrate embodiments of the invention and their descriptions, serving to explain the principles of the invention.

[0031] In the attached image:

[0032] Figure 1 A schematic diagram of a monitoring method for the annealing process in the related art is shown.

[0033] Figure 2 A flowchart of a monitoring method for the annealing process in one embodiment of this application is shown.

[0034] Figure 3 A flowchart of a monitoring method for the annealing process in another embodiment of this application is shown.

[0035] Figure 4 A schematic diagram of the annealing equipment in an embodiment of this application is shown.

[0036] Figures 5A-5C A cross-sectional schematic diagram of the relevant steps in the monitoring method for the annealing process of the monitored wafer in the embodiments of this application is shown. Detailed Implementation

[0037] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention.

[0038] It should be understood that the invention can be embodied in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, for clarity, the dimensions and relative dimensions of layers and regions may be exaggerated. The same reference numerals denote the same elements throughout.

[0039] 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 may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, 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., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this invention, the first element, component, area, layer, or portion discussed below may be referred to as the second element, component, area, layer, or portion.

[0040] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below” or “under” the other element or feature will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0041] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. When used herein, the singular forms “a,” “an,” and “ / the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “comprising,” when used in this specification, identify the presence of features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0042] To fully understand this invention, detailed steps and structures will be set forth in the following description to illustrate the technical solution proposed by this invention. Preferred embodiments of the invention are described in detail below; however, in addition to these detailed descriptions, the invention may have other embodiments.

[0043] For high-temperature annealing processes, many related technologies use silicon wafers as monitoring wafers in high-temperature annealing furnaces to monitor the level of impurity contamination released by quartz components and the stability of the process during annealing.

[0044] like Figure 1 The diagram illustrates a furnace tube annealing monitoring method in related technologies. After a product film layer is deposited on the surface of a product wafer, it is placed in a furnace tube for annealing to improve the density of the product film layer; or, the surface of the product wafer is annealed to form an oxide layer. The furnace tube includes quartz components, which typically contain impurities such as Cl, F, and -OH (hydroxyl groups). The annealing temperature is usually high, for example, 950℃ to 1300℃. At this temperature, the impurities diffuse, affecting the quality of the film layer on the product wafer surface. For example, when the product film layer on the product wafer surface is silicon oxide, or when the product wafer surface is oxidized to form silicon oxide, the impurities (such as Cl, F, or -OH) corrode the silicon oxide, leaving pit defects in the silicon oxide layer.

[0045] In existing technologies, such as Figure 1 As shown, monitoring wafers are typically used to monitor defects in product wafers. Monitoring wafers are usually bare silicon wafers with silicon as their surface material. Impurities can also cause corrosion defects such as pitting defects in Si materials. However, impurities such as Cl, F, or -OH released by quartz components at high temperatures have a low corrosion rate on Si materials, resulting in small corrosion defects, usually concentrated within 45nm, which are difficult to detect and monitor. Therefore, bare silicon monitoring wafers are difficult to use to monitor the impact of impurities on product wafers.

[0046] Furthermore, although a silicon dioxide film 120 will form on the surface of the monitoring wafer 110 during the natural oxidation process, its thickness is very thin, making it difficult to form a sufficient number and size of pit defects 140 on the monitoring wafer 110. This also makes it difficult to detect and monitor pit defects caused by the diffusion of impurities, thereby affecting the monitoring accuracy of the annealing process.

[0047] To address the aforementioned problems, embodiments of this application provide a method for monitoring the annealing process, such as... Figure 2 As shown, this method includes the following steps:

[0048] In step S210: a monitoring wafer is provided, including a first substrate wafer and a monitoring film layer on the surface of the first substrate wafer.

[0049] In step S220: the monitoring wafer is placed in the furnace tube of the annealing equipment for annealing process, the annealing equipment including a quartz component.

[0050] In step S230: the level of pit defects in the monitoring film after annealing is detected to obtain the level of contamination in the furnace tube by impurities released by the quartz component during the annealing process. During the annealing process, the corrosion rate of the monitoring film by impurities is higher than the corrosion rate of the first substrate wafer.

[0051] The annealing process monitoring method in this application involves a monitoring wafer comprising a first substrate wafer and a monitoring film layer on the surface of the first substrate wafer. The monitoring wafer is placed in the furnace tube of an annealing equipment for annealing. By detecting the level of pit defects in the monitoring film layer after annealing, the contamination level of impurities released by the quartz component during annealing within the furnace tube can be obtained. Therefore, if impurities are present during annealing, their diffusion will corrode the monitoring film layer, thereby forming pit defects in the monitoring film. Since the corrosion rate of impurities on the monitoring film layer is higher than that on the first substrate wafer during annealing, compared to using a silicon wafer as the monitoring wafer, the monitoring method of this application can form larger pit defects in the monitoring film if impurities are present during annealing. This makes the pit defects easier to detect, and the level of pit defects can be used to determine the contamination level of impurities released by the quartz component during annealing within the furnace tube. This improves the detection accuracy and sensitivity of impurities, thereby reducing product scrap and equipment downtime caused by impurities, lowering production costs, and increasing production efficiency.

[0052] More specifically, in step S210, first refer to Figure 5A A first substrate wafer 510 is provided. Exemplarily, the first substrate wafer 510 is a silicon wafer or other suitable wafer.

[0053] Refer to Figure 5B A monitoring film 520 is deposited on the surface of the first substrate wafer 510, and the first substrate wafer 510 and the monitoring film 520 constitute a monitoring wafer 500.

[0054] The monitoring film 520 can be formed using various deposition processes commonly used in the art. For example, the monitoring film 520 can be formed on the surface of the first substrate wafer 510 using any suitable deposition method such as low-pressure chemical vapor deposition, physical vapor deposition, or atomic layer deposition. This embodiment does not impose any limitations on this method. It should be noted that if multiple monitoring wafers simultaneously undergo high-temperature annealing, they must be prepared under the same process conditions to ensure that variables in the monitoring method are controllable.

[0055] Optionally, the thickness of the monitoring film 520 can be between 10nm and 800nm, such as any suitable thickness of 10nm, 50nm, 100nm, 150nm, 200nm, 300nm, 500nm, 600nm, 700nm or 800nm, or any other suitable thickness, which can be selected according to the actual situation.

[0056] The monitoring film 520 with a thickness greater than or equal to 10 nm is contaminated and corroded by impurities during high-temperature annealing, which can form large-sized pit defects, reducing the difficulty of subsequent defect detection; the monitoring film 520 with a thickness less than or equal to 800 nm can reduce the preparation cost of the monitoring film 520.

[0057] The monitoring film 520 is made of at least one of the following materials: silicon oxide, polycrystalline silicon, aluminum oxide, silicon nitride, or any other suitable material. When the monitoring film obtained from the above materials undergoes a high-temperature annealing process together with the monitoring wafer 500, impurities released from the quartz component cause a faster corrosion rate to the monitoring film 520 relative to the first substrate wafer, thereby facilitating the formation of easily detectable pit defects 530.

[0058] like Figure 4 The diagram shown is a schematic of the annealing equipment used in the monitoring method of this application embodiment. The annealing equipment 400 includes a quartz component, which includes a furnace tube, such as a quartz tube 430. The quartz component also includes a quartz crystal boat 410, a gas pipeline (not shown), and an igniter 440.

[0059] The quartz tube 430 has a cavity. A quartz boat 410 is used to hold product wafers and monitoring wafers; during annealing, the quartz boat 410 is placed inside the cavity of the furnace tube, such as the quartz tube 430. A gas passage is connected to the quartz tube 430 for introducing gas into it. An igniter 440 is used to ignite the gas, such as hydrogen and oxygen, and to generate the reactant water. It is understood that the specific gas introduced during the annealing process can be selected according to actual needs; in some embodiments, an inert gas is introduced to provide an inert annealing environment.

[0060] For example, the quartz tube 430, igniter 440, gas pipeline and crystal boat 410 are all made of quartz. In high-temperature environments, impurities in the quartz components inevitably diffuse. In particular, when the furnace tube operates at a high temperature of 1000°C or above, impurities in the quartz components of the annealing equipment will diffuse exponentially, making it easier to generate high-temperature corrosion defects. Therefore, it is necessary to monitor the annealing process using the monitoring method in this application embodiment to monitor the level of impurities released by the quartz components. The level of impurities can refer to the level of impurities in the furnace tube.

[0061] Therefore, after obtaining the monitoring wafer 500, step S220 can be performed, placing the monitoring wafer 500 in the furnace tube of the annealing equipment for annealing, and monitoring the annealing process through the monitoring wafer 500. In the annealing process, the annealing temperature range is 950℃~1300℃, or other suitable temperature ranges. The annealing time in the process can be adjusted according to the available time.

[0062] For example, during the annealing process, the quartz component releases impurities under high-temperature conditions, primarily including at least one of the following impurities: Cl, F, -OH, or other corrosive impurities. During the annealing process, the impurities released by the quartz under high-temperature conditions can corrode the monitoring film layer 520. Figure 5C As shown, pit defects 530 are formed in the monitoring film layer 520.

[0063] The corrosion rate of the monitoring film 520 due to impurities is greater than that of the first substrate wafer 510, thus forming pit defects 530 on the surface of the monitoring film 520, and the pit defects 530 have a large size (e.g., the size of the pit defects is greater than or equal to 300 nm). Therefore, it is convenient to monitor the impurities released from the quartz component through the pit defects 530.

[0064] Furthermore, in step S230, the level of pit defects in the monitoring film after annealing is detected to obtain the level of contamination in the furnace tube caused by impurities released by the quartz component during the annealing process.

[0065] For example, the pit defect level can be determined by detecting the number of pit defects 530 or the number of pit defects of different sizes. The pit defect level reflects the level of contamination by impurities in the furnace tube. Generally, the larger the number of pit defects 530, the higher the pit defect level, which in turn reflects the higher level of contamination by impurities released from the quartz component during annealing. Furthermore, when the product wafer and the monitoring wafer are annealed simultaneously, the pit defect level of the monitoring film layer 520 can also reflect the degree of influence of impurities released from the quartz component during annealing on the product wafer. Generally, the larger the number of pit defects 530, the higher the pit defect level, and the greater the influence on the product wafer. The number and size of pit defects 530 can be detected by any suitable method, such as optical microscopy, electron microscopy, or automated defect detection systems. In the scheme of this application, the size of the pit defects 530 formed is larger, for example, larger than the resolution of the detection equipment, making them easier to capture and detect by the detection equipment, thereby increasing the number of detectable pit defects 530.

[0066] For example, the size of the pit defect 530 formed in the monitoring film layer 520 is greater than or equal to 300 nm, that is, a larger pit is formed, or it may be other suitable size range, and therefore more easily detected.

[0067] Compared to methods that directly utilize a monitoring wafer, such as a first substrate wafer, for pit defect detection, this application provides a monitoring film layer 520 on the first substrate wafer 510. This monitoring film layer 520 has sufficient thickness, and the corrosion rate of the monitoring film layer due to impurities is higher than that of the first substrate wafer 510. Therefore, after annealing, it is possible to more accurately monitor whether pit defects caused by corrosion from impurities released from the quartz component have occurred, and to determine the level of contamination of impurities released from the quartz component within the furnace tube based on the pit defect level. Furthermore, increasing the thickness of the monitoring film layer can also increase the number of pit defects that can be detected by the monitoring film layer. For example, compared with directly using bare silicon wafers as monitoring wafers, which can detect a dozen or so defects, this embodiment of the application uses the pit defects 530 generated by the high-temperature corrosion monitoring film 520 caused by the diffusion of quartz impurities (Cl, F, OH, etc.) at high temperatures to monitor the impurity contamination caused by the diffusion of impurities in the quartz component at high temperatures. Due to the increase in the size of the pit defects, the number of pit defects that can be detected can be increased to dozens or even hundreds (optionally, the number of defects is positively correlated with the thickness of the monitoring film).

[0068] It is worth mentioning that the monitoring wafer can be used separately to monitor the impurities released by the quartz components during the annealing process, that is, to monitor the impurities released by the quartz components of the annealing equipment.

[0069] Another approach is to simultaneously anneal both the monitoring wafer and the product wafer. By detecting pit defects formed in the monitoring film layer of the monitoring wafer, the contamination released from the quartz components of the annealing equipment can be monitored. The obtained contamination level can be used to determine the extent of the contamination's impact on the product wafer (including the product film layer), i.e., the degree of impact of the contamination on the product film layer. This can be understood as confirming the impact of contamination on the product film layer through the contamination level. This includes confirming the level of pit defects caused by contamination on the product film layer by monitoring the number of pit defects on the film layer, for example, when the pit defects caused by contamination on the product film layer are small and difficult to detect.

[0070] Specifically, both the monitoring wafer and the product wafer can be placed in the furnace tube of an annealing equipment for annealing. The product wafer includes a second substrate wafer and a product film layer on the surface of the second substrate wafer. Alternatively, the annealing process forms a product film layer (such as a silicon oxide film layer or a silicon nitride film layer) on the surface of the product wafer. In this case, impurities corrode the monitoring film layer at a higher rate than they corrode the product film layer. Therefore, if impurities are present in the furnace tube, they are more likely to cause significant corrosion and larger pit defects in the monitoring film layer of the monitoring wafer. This improves the accuracy and sensitivity of pit defect detection, reduces detection difficulty, and consequently reduces product scrap and equipment downtime caused by impurities, lowering production costs and increasing production efficiency. Furthermore, annealing the monitoring wafer and the product wafer together ensures that the monitoring results accurately reflect the process environment of the product wafer.

[0071] In some instances, the corrosion rate of the monitoring film is equal to that of the product film, for example, when the monitoring film and the product film are made of the same material. Therefore, the impact of impurity contamination on the product film can be determined by detecting the number of depressions formed on the monitoring film, reducing wafer loss during defect detection.

[0072] It is worth mentioning that the second substrate wafer can be a silicon wafer or any other suitable material wafer, and the material of the product film layer can be at least one of the following: silicon oxide, polycrystalline silicon, aluminum oxide, and silicon nitride. The specific material can be selected according to actual needs, and no specific limitation is made here.

[0073] In some examples, the monitoring film layer can have the same thickness as the product film layer. In other examples, the thickness of the monitoring film layer can be greater than that of the product film layer. This configuration allows impurities to easily form larger pit defects when they corrode the monitoring film layer, making them easier for detection equipment to capture and thus increasing the number of detectable pit defects.

[0074] In some examples, the degree of change in the density of the product film layer on the product wafer due to the annealing process can also be monitored, for example, as... Figure 3 As shown, the monitoring method in this application embodiment further includes the following steps:

[0075] First, in step S310, before the annealing process, the thickness of the monitoring film layer before annealing is detected. More specifically, as... Figure 5B As shown, the thickness L1 of the monitoring film layer 520 before annealing is obtained before the annealing process, that is, the thickness of the monitoring film layer 520 before the annealing process is obtained. The thickness of the monitoring film layer 520 can be detected using any suitable thickness measuring instrument known to those skilled in the art, such as an ellipsometer or interferometer.

[0076] Next, in step S320, the monitoring wafer and the product wafer are placed in the furnace tube of the annealing equipment for annealing. The product wafer includes a second substrate wafer and a product film layer located on the surface of the second substrate wafer. The monitoring film layer and the product film layer are prepared under the same process conditions.

[0077] The monitoring film and the product film are prepared using the same process conditions, which means that they can be deposited using exactly the same process parameters, and they can also have the same thickness and the same material to ensure that they have a high degree of consistency in structure and properties.

[0078] Next, in step S330, after the annealing process is completed, the thickness of the film layer after annealing is detected and monitored. For example... Figure 5C As shown, after the annealing process, the thickness L2 of the monitoring film 520 after annealing is obtained again. Although the impurities released by the quartz during the annealing process will corrode the monitoring film 520, it mainly manifests as pit defects 530 and will not affect the measurement of the overall thickness of the monitoring film 520.

[0079] Next, in step S340, the degree of change in the density of the product film before and after the annealing process is determined based on the thickness before and after annealing. For example, the degree of change in the density of the product film before and after the annealing process can be determined by monitoring the thickness difference between the thickness before and after annealing, where a larger thickness difference indicates a higher degree of change in density. Alternatively, the degree of change in the density of the product film before and after the annealing process can also be determined by monitoring the ratio of the thickness L1 before annealing to the thickness L2 after annealing (i.e., L1 / L2), where a larger ratio indicates a higher degree of change in density. Yet another example is obtaining the thickness change rate by subtracting L2 from L1 and then dividing by L1, using this thickness change rate to represent the degree of change in the density of the product film before and after the annealing process, where a larger thickness change rate indicates a higher degree of change. Of course, other suitable methods can also be used to determine the degree of change in the density of the product film before and after the annealing process.

[0080] Therefore, by preparing the monitoring film and the product film under the same process conditions, a high degree of consistency in structure and properties can be ensured. Simultaneous annealing can guarantee the same thermal history. Thus, changes in the thickness of the monitoring film can more accurately reflect changes in the density of the product film, which helps reduce the risk of wafer breakage that may result from directly measuring the product wafer.

[0081] For example, during the annealing process, multiple product wafers are annealed using annealing equipment. The same monitoring film layer is formed on both the monitoring wafer and the product wafer under identical deposition conditions, thus maintaining a high degree of consistency between the monitoring film layers on the monitoring wafer and the product wafer. Furthermore, by monitoring the change in the thickness of the monitoring film layer on the monitoring wafer before and after annealing, the change in the density of the monitoring film layer on the actual product wafer can be reflected, thereby monitoring the stability of the monitoring film layer density. It is worth noting that the product wafer is the wafer actually used for semiconductor device fabrication.

[0082] Exemplary, the method in this application embodiment further includes the following steps A1 to A2:

[0083] In step A1, a filler wafer is provided, which includes a third substrate wafer and a baffle film layer disposed on the surface of the third substrate wafer.

[0084] The aforementioned monitoring film layer of the monitoring wafer, the product film layer of the product wafer, and the baffle film layer of the filling wafer can be prepared under the same process conditions. For example, the three can be deposited using the exact same process parameters, and they can also have the same thickness and the same material to ensure that the three have a high degree of consistency in structure and properties.

[0085] In step A2, multiple product wafers, at least one monitoring wafer, and at least one filler wafer are placed in a crystal boat and placed in the furnace tube of an annealing equipment for annealing. The filler wafer is used as a baffle.

[0086] It should be noted that during the annealing process, multiple product wafers are typically placed in the quartz crystal boat 410. When the number of product wafers cannot fill all the slots of the quartz crystal boat 410, some of the extra slots can be filled with filler wafers as baffles. For example, if the quartz crystal boat 410 of the annealing equipment can hold 125 wafers, but only 80 product wafers actually need to be annealed, filler wafers can be placed in the extra slots of the quartz crystal boat 410 as baffles, after placing the necessary monitoring wafers. For example, filler wafers can be placed in the slots at both ends of the quartz crystal boat 410, as well as in other slots. This arrangement allows the product wafers in the annealing equipment to maintain basically similar annealing conditions, resulting in more uniform heat radiation and more stable heat distribution. Therefore, using filler wafers as baffles can effectively reduce the back-side effect in the annealing process, making the annealing process more stable and efficient. Monitoring wafers are primarily used to monitor impurity contamination, thus requiring a higher number of pit defects. Filled wafers, used to improve heat distribution, have lower requirements for the number of pit defects. Subsequent pit defect detection mainly involves monitoring impurity contamination by monitoring pit defects on the wafer. In some embodiments, changes in the baffle film layer of the filled wafer can also be used to monitor the thickness of the product film layer, to confirm the degree of change in the density of the product film layer before and after the annealing process.

[0087] In summary, the annealing process monitoring method in this application involves depositing a monitoring film layer on a first substrate wafer to prepare a monitoring wafer. Then, by detecting the presence of pit defects on the monitoring film layer after annealing, it is possible to confirm the presence of impurities released from quartz components during the annealing process within the furnace tube. The monitoring film layer amplifies the pit defects formed by impurities when viewed from above. Compared to methods that directly monitor the first substrate wafer, such as a silicon wafer, this application can more accurately identify impurities, ensuring the accuracy of the annealing process monitoring method. Furthermore, it facilitates the confirmation of changes in the density of the product film layer by examining the thickness of the monitoring film layer before and after the annealing process. Compared to related technologies, the monitoring method in this application has the advantages of being more efficient and reliable.

[0088] Although exemplary embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above exemplary embodiments are merely illustrative and are not intended to limit the scope of this application. Various changes and modifications can be made therein by those skilled in the art without departing from the scope and spirit of this application. All such changes and modifications are intended to be included within the scope of this application as claimed in the appended claims.

[0089] Similarly, it should be understood that, in order to simplify this application and aid in understanding one or more aspects of the application, various features of this application may sometimes be grouped together in a single embodiment, figure, or description thereof in the description of exemplary embodiments of this application. However, this approach should not be construed as reflecting an intention that the claimed application requires more features than are expressly recited in each claim. Rather, as reflected in the corresponding claims, the point of application is that the corresponding technical problem can be solved with fewer features than all of a single disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of this application.

[0090] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the claims, any of the claimed embodiments can be used in any combination.

[0091] It should be noted that the above embodiments are illustrative of this application and not limiting of it, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

Claims

1. A method for monitoring an annealing process, characterized in that, The method includes: Provide a monitoring wafer, including a first substrate wafer and a monitoring film layer on the surface of the first substrate wafer; The monitoring wafer is placed in the furnace tube of an annealing equipment for annealing, the annealing equipment including a quartz component; The level of pit defects in the monitoring film layer after annealing is detected to obtain the level of contamination in the furnace tube by impurities released by the quartz component during the annealing process. During the annealing process, the corrosion rate of the monitoring film due to impurities is higher than the corrosion rate of the first substrate wafer.

2. The monitoring method as described in claim 1, characterized in that, The monitoring method also includes: Before the annealing process, the thickness of the monitoring film layer before annealing is detected; The monitoring wafer and the product wafer are placed in the furnace tube of the annealing equipment for annealing. The product wafer includes a second substrate wafer and a product film layer located on the surface of the second substrate wafer. The monitoring film layer and the product film layer are prepared under the same process conditions. After the annealing process is completed, the thickness of the monitoring film layer after annealing is detected. The degree of change in the density of the product film layer before and after the annealing process is determined based on the thickness before and after the annealing process.

3. The monitoring method as described in claim 1, characterized in that, The monitoring method includes: The monitoring wafer and the product wafer are placed in the furnace tube of an annealing apparatus for an annealing process. The product wafer includes a second substrate wafer and a product film layer located on the surface of the second substrate wafer; or, the annealing process forms a product film layer on the surface of the product wafer. The corrosion rate of the monitoring film due to the impurity contamination is higher than or equal to the corrosion rate of the product film, and the degree of influence of the impurity contamination on the product film is determined by the contamination level.

4. The monitoring method as described in claim 1, characterized in that, The monitoring method includes: The monitoring wafer and the product wafer are placed in the furnace tube of an annealing apparatus for an annealing process. The product wafer includes a second substrate wafer and a product film layer located on the surface of the second substrate wafer; or, the annealing process forms a product film layer on the surface of the product wafer. The thickness of the monitoring membrane is greater than the thickness of the product membrane, and the degree of influence of the impurity contamination on the product membrane is determined by the contamination level.

5. The monitoring method according to any one of claims 1 to 4, characterized in that, The thickness of the monitoring film ranges from 10nm to 800nm.

6. The monitoring method according to any one of claims 1 to 4, characterized in that, The size of the pit defect is greater than or equal to 300 nm.

7. The monitoring method according to any one of claims 1 to 4, characterized in that, The first substrate wafer includes a silicon wafer.

8. The monitoring method according to any one of claims 1 to 4, characterized in that, The material of the monitoring film includes at least one of the following: silicon oxide, polycrystalline silicon, aluminum oxide, and silicon nitride.

9. The monitoring method according to any one of claims 1 to 4, characterized in that, The monitoring film is formed by deposition using low-pressure chemical vapor deposition, physical vapor deposition, or atomic layer deposition.

10. The monitoring method according to any one of claims 1 to 4, characterized in that, The impurity contamination includes at least one of the following impurities: Cl, F, -OH; and / or The annealing temperature range of the annealing process is 950℃~1300℃.

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