Wafer processing method and wafer
By spraying etchant at the edge of the oxide layer and cleaning agent at the center while the wafer is rotating, the problem of uneven oxide layer thickness on the wafer has been solved, thus improving wafer yield and process efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-22
- Publication Date
- 2026-04-07
AI Technical Summary
In semiconductor manufacturing, during the oxidation process, the unevenness of the wafer oxide layer thickness in the lower region of the wafer boat leads to a low wafer yield.
Under wafer rotation conditions, etchant is sprayed onto the edge area of the concave oxide layer, and cleaning agent is sprayed onto the middle area. The contact time of the etchant is controlled to be no later than that of the cleaning agent. The rotation speed is 500rpm~1500rpm. By adjusting the mass fraction of the etchant and the spraying time, the synergistic effect between the cleaning agent and the etchant is ensured, and the etching rate is gradually increased to form a plane.
It significantly improves the uniformity of oxide layer thickness, increases wafer yield, and reduces costs.
Smart Images
Figure CN121815971A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of semiconductor technology, in particular to a wafer processing method and a wafer. BACKGROUND
[0002] In the field of semiconductor manufacturing, oxidation process is a key step for forming oxide layer, and is widely used in the preparation of oxide film on silicon wafer, silicon on insulator (SOI), piezoelectric on insulator (POI), silicon carbide on insulator (SiCOI) and other substrates, and related device manufacturing processes.
[0003] At present, the oxidation process is usually carried out in a high-temperature vertical furnace. In actual process, the product wafers are generally uniformly loaded in a silicon carbide (SiC) boat in an amount of no more than 130 pieces, and are distributed in four areas of upper, middle upper, middle lower and lower. Due to the limitations of hardware design of processing equipment and process characteristics, the uniformity of the oxide layer formed on the surface of the wafer located in the lower area of the boat is often worse than that of other areas, which is difficult to meet the actual application requirements, thereby resulting in a low yield of wafers prepared by using the oxidation process. SUMMARY
[0004] Therefore, the embodiments of the present application provide a wafer processing method and a wafer to solve at least one problem in the background art.
[0005] In a first aspect, the embodiments of the present application provide a wafer processing method, which comprises: providing a wafer, the wafer comprising a substrate and an oxide layer located on the substrate; a surface of the oxide layer away from the substrate is a concave surface; under the condition that the wafer rotates, spraying an etching liquid to an edge area of the concave surface and spraying a cleaning agent to a middle area of the concave surface to perform etching treatment on the oxide layer, so that the surface of the oxide layer away from the substrate forms a plane; the rotation rate of the wafer is 500 rpm-1500 rpm; the etching liquid contacts the concave surface no later than the cleaning agent contacts the concave surface; The method satisfies the following relationship: ; wherein U is the thickness uniformity of the oxide layer, specifically the difference between the maximum thickness and the minimum thickness of the oxide layer accounts for the percentage of the average thickness of the oxide layer; T is the average thickness of the oxide layer, in units of nm; Q is the mass fraction of the etching liquid; t is the spraying time of the etching liquid, in units of s.
[0006] In conjunction with the first aspect of this application, in an optional embodiment, Q is 1% to 10%; and / or, the corrosive liquid includes hydrofluoric acid; and / or, the cleaning agent includes one or more of deionized water, ultrapure water, and ozone.
[0007] In conjunction with the first aspect of this application, in an optional embodiment, the distance from the spray area of the cleaning agent on the concave surface to the central axis of the wafer is less than half the radius of the wafer; optionally, the center of the spray area of the cleaning agent on the concave surface is located on the central axis of the wafer.
[0008] In conjunction with the first aspect of this application, in an optional embodiment, the first spray source of the cleaning agent moves in a direction parallel to the plane of the substrate; optionally, the moving speed of the first spray source is less than or equal to 100 mm / s.
[0009] In conjunction with a first aspect of this application, in an alternative embodiment, the distance from the sprayed area of the etchant on the concave surface to the central axis of the wafer is greater than or equal to half the radius of the wafer.
[0010] In conjunction with the first aspect of this application, in an optional embodiment, the second spray source of the etchant moves in a direction parallel to the plane of the substrate; optionally, the moving speed of the second spray source is less than or equal to 100 mm / s.
[0011] In conjunction with the first aspect of this application, in an optional embodiment, the distance between the first spray source of the cleaning agent and the tangential surface at the center point of the concave surface is greater than or equal to the distance between the second spray source of the corrosive liquid and the tangential surface at the center point of the concave surface; and / or, the distance between the first spray source of the cleaning agent and the tangential surface at the center point of the concave surface is 1cm to 10cm; and / or, the distance between the second spray source of the corrosive liquid and the tangential surface at the center point of the concave surface is 1cm to 10cm.
[0012] In conjunction with the first aspect of this application, in an optional embodiment, the flow rate of the cleaning agent is less than or equal to the flow rate of the corrosive liquid; and / or, the flow rate of the cleaning agent is 0.2 L / min to 1 L / min; and / or, the flow rate of the corrosive liquid is 0.2 L / min to 1 L / min.
[0013] In conjunction with the first aspect of this application, in an optional embodiment, after the wafer is processed, the thickness uniformity of the oxide layer is less than or equal to 1.5%.
[0014] Secondly, embodiments of this application provide a wafer fabricated using the wafer processing method described in any one of the first aspects.
[0015] Compared with the prior art, the embodiments of this application have the following beneficial effects: In the wafer processing method provided in this application embodiment, under the condition of wafer rotation, an etchant is sprayed onto the edge region of the concave surface of the oxide layer, and a cleaning agent is sprayed onto the middle region of the concave surface of the oxide layer to etch the oxide layer. By controlling the time when the etchant contacts the concave surface to be no later than the time when the cleaning agent contacts the concave surface, it can be ensured that the etchant reaches the concave surface first and is fully dispersed. When the cleaning agent reaches the concave surface, under the condition of wafer rotation, when the cleaning agent contacts the etchant, it can effectively dilute the etchant. Through the combination of the cleaning agent and the etchant, the concentration of the etchant gradually increases along the radial direction of the wafer from the center to the edge. When the wafer rotation speed is too low, it is difficult to ensure the effective combination of the cleaning agent and the etchant. When the wafer rotation speed is too high, the cleaning agent and the etchant are easily thrown off the oxide layer before they can play their role. Therefore, in this application embodiment, the wafer rotation speed is controlled at 500 rpm to 1500 rpm. At the same time, the mass fraction Q of the etchant and the spraying time t of the etchant are controlled according to the thickness uniformity U and the average thickness T of the oxide layer, so that... This ensures effective interaction between the cleaning agent and the etching solution, resulting in an increasing etching rate of the oxide layer along the wafer radial direction from the center to the edge. This etching rate adapts to the concave morphology of the oxide layer, allowing the surface of the oxide layer furthest from the substrate to form a planar surface. After processing the wafer using the wafer processing method provided in this application, the uniformity of the oxide layer thickness can be significantly improved, thereby increasing the wafer yield.
[0016] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description
[0017] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 A schematic flowchart of the wafer processing method provided in the embodiments of this application; Figure 2 This is a schematic diagram of the cross-sectional structure of a wafer before processing, provided in an embodiment of this application. Figure 3 This is a side view of an embodiment of the present application showing the application of a corrosion treatment performed by spraying cleaning agent and etching solution onto the concave surface of the oxide layer; Figure 4 This is a top view of an embodiment of the present application showing the application of a corrosion treatment performed by spraying cleaning agent and etching solution onto the concave surface of the oxide layer; Figure 5 This is a schematic cross-sectional view of the processed wafer in an embodiment of this application. Figure 6 This is a morphological diagram showing the thickness distribution of the oxide layer in the wafer after high-temperature oxidation in Example 6; Figure 7 This is a thickness distribution morphology diagram of the oxide layer after etching treatment in Example 6. Detailed Implementation
[0018] Exemplary embodiments of the present application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application may be implemented in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present application and to fully convey the scope of the disclosure of the present application to those skilled in the art.
[0019] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of this application. However, it will be apparent to those skilled in the art that this application can be practiced without one or more of these details. In other instances, to avoid confusion with this application, some technical features well-known in the art have not been described; that is, not all features of actual embodiments are described herein, nor are well-known functions and structures described in detail.
[0020] In the accompanying drawings, for clarity, the dimensions of layers, areas, and elements, as well as their relative dimensions, may be exaggerated. The same reference numerals denote the same elements throughout.
[0021] 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. 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 application, the first element, component, area, layer, or portion discussed below may be referred to as a second element, component, area, layer, or portion. And the discussion of a second element, component, area, layer, or portion does not imply that the first element, component, area, layer, or portion necessarily exists in this application.
[0022] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship of one element or feature shown in the figure to other elements or features. 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.
[0023] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. The terms “comprising” and / or “including,” when used in this specification, identify the presence of said 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.
[0024] To fully understand this application, detailed steps and structures will be presented in the following description to illustrate the technical solution of this application. Preferred embodiments of this application are described in detail below; however, in addition to these detailed descriptions, this application may have other implementation methods.
[0025] This application provides a wafer processing method. Please refer to the embodiments provided. Figure 1 The wafer processing method provided in this application includes: Step S101: Provide a wafer, the wafer including a substrate and an oxide layer on the substrate; the surface of the oxide layer away from the substrate is concave; Step S102: Under the condition of wafer rotation, an etchant is sprayed onto the edge area of the concave surface and a cleaning agent is sprayed onto the middle area of the concave surface to etch the oxide layer, so that the surface of the oxide layer away from the substrate forms a plane; the wafer rotation speed is 500 rpm to 1500 rpm; the time when the etchant contacts the concave surface is no later than the time when the cleaning agent contacts the concave surface. The above method satisfies the following relationship: ; Wherein, U represents the uniformity of oxide layer thickness, specifically the percentage of the difference between the maximum and minimum oxide layer thickness to the average oxide layer thickness; T represents the average oxide layer thickness in nm; Q represents the mass fraction of the etchant; and t represents the spraying time of the etchant in seconds.
[0026] In this embodiment, under wafer rotation conditions, an etchant is sprayed onto the edge region of the concave oxide layer, and a cleaning agent is sprayed onto the middle region of the concave oxide layer to etch the oxide layer. By controlling the contact time of the etchant with the concave surface to be no later than the contact time of the cleaning agent, it can be ensured that the etchant reaches the concave surface first for sufficient dispersion. When the cleaning agent reaches the concave surface, under wafer rotation conditions, the cleaning agent can effectively dilute the etchant upon contact with it. Through the interaction of the cleaning agent and the etchant, the concentration of the etchant gradually increases along the radial direction of the wafer from the center to the edge. When the wafer rotation speed is too low, it is difficult to ensure the effective interaction between the cleaning agent and the etchant. When the wafer rotation speed is too high, the cleaning agent and the etchant are easily thrown off the oxide layer before they can function. Therefore, in this embodiment, the wafer rotation speed is controlled at 500 rpm to 1500 rpm. Simultaneously, the mass fraction Q of the etchant and the spraying time t of the etchant are controlled according to the uniformity U and the average thickness T of the oxide layer, so that... This ensures effective interaction between the cleaning agent and the etching solution, resulting in an increasing etching rate of the oxide layer along the wafer radial direction from the center to the edge. The etching rate also adapts to the concave morphology of the oxide layer, allowing the surface of the oxide layer furthest from the substrate to form a planar surface. After processing the wafer using the wafer processing method provided in this application, the uniformity of the oxide layer thickness can be significantly improved, thereby increasing the wafer yield.
[0027] Below, in conjunction with Figures 2 to 5 The wafer processing method and its corresponding beneficial effects provided in the embodiments of this application will be further described in detail.
[0028] First, please refer to Figure 2 In step S101, a wafer 100 is provided, which includes a substrate 110 and an oxide layer 120 located on the substrate 110; the surface of the oxide layer 120 away from the substrate 110 is a concave surface 121.
[0029] In this embodiment, the substrate 110 can be made of materials such as silicon, germanium, silicon-germanium, or silicon carbide. The oxide layer 120 can be formed by oxidizing the surface of the substrate 110; therefore, the material of the oxide layer 120 can be silicon oxide and / or germanium oxide. Of course, this embodiment does not limit the formation method of the oxide layer 120. As long as the surface of the oxide layer 120 away from the substrate 110 is concave, the wafer processing method provided in this embodiment can be used for processing.
[0030] In some embodiments, the method for fabricating wafer 100 may include: first, providing substrate 110; and next, subjecting substrate 110 to high-temperature oxidation.
[0031] For example, the temperature of high-temperature oxidation can be greater than or equal to 1000°C, and the high-temperature oxidation time can be greater than or equal to 10 minutes. High-temperature oxidation can be dry oxygen oxidation and / or wet oxygen oxidation. High-temperature oxidation can be performed in one step or in stages.
[0032] Secondly, please refer to Figure 3 and Figure 4 In step S102, while the wafer 100 is rotating, an etchant is sprayed onto the edge region of the concave surface 121, and a cleaning agent is sprayed onto the middle region of the concave surface 121 to etch the oxide layer 120, so that the surface of the oxide layer 120 away from the substrate 110 forms a plane; the rotation speed of the wafer 100 is 500 rpm to 1500 rpm; the time when the etchant contacts the concave surface 121 is no later than the time when the cleaning agent contacts the concave surface 121; the above method satisfies the following relationship: Wherein, U represents the thickness uniformity of oxide layer 120, specifically the percentage of the difference between the maximum and minimum thickness of oxide layer 120 to the average thickness of oxide layer 120; T represents the average thickness of oxide layer 120, in nm; Q represents the mass fraction of the etching solution; and t represents the spraying time of the etching solution, in s.
[0033] In this embodiment, the average thickness T of the oxide layer 120 can be taken as the average value of the oxide layer thickness at different points on the concave surface 121 of the oxide layer 120. The number of points taken can be determined according to the size of the wafer, and the points taken can be uniformly distributed on the concave surface 121. For example, the commonly used 49-point measurement method in the industry involves 49 measurement points arranged on the wafer in polar coordinates, including the center point and points distributed at equal angles on multiple concentric rings. By measuring the oxide layer thickness at all measurement points, the average thickness of the oxide layer can be obtained, and the uniformity of the oxide layer thickness can be calculated. For example, it can be 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, or any value between any two of the above ranges.
[0034] Understandable.Figure 4 The direction of the dotted-line arrow in the diagram is merely illustrative of the direction of wafer 100's rotation. In actual processing, wafer 100 can rotate clockwise or counterclockwise. The rotational speed of wafer 100 can be, for example, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, 1100 rpm, 1200 rpm, 1300 rpm, 1400 rpm, 1500 rpm, or any value between any two of the above ranges.
[0035] It should be noted that, in this embodiment, the moment the etchant contacts the concave surface 121 is no later than the moment the cleaning agent contacts the concave surface 121 means that the moment the etchant first contacts the concave surface 121 is no later than the moment the cleaning agent first contacts the concave surface 121. From the moment the cleaning agent contacts the concave surface 121, the etchant and cleaning agent begin to be sprayed simultaneously onto the concave surface 121. In some specific embodiments, the moment the etchant contacts the concave surface 121 is earlier than the moment the cleaning agent contacts the concave surface 121. Thus, by controlling the etchant to reach the concave surface 121 before the cleaning agent, under the action of the wafer 100 rotation, it is better ensured that the etchant is fully dispersed on the concave surface 121 first. When the cleaning agent reaches the concave surface 121, it can more uniformly and comprehensively dilute the dispersed etchant, improving the synergistic effect between the cleaning agent and the etchant, thereby improving the uniformity of the treatment of the entire concave surface 121.
[0036] In some embodiments, the mass fraction Q of the etching solution can be 1% to 10%, for example, it can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any value between any two of the above ranges. This allows for adjustment of the mass fraction of the etching solution to suit the morphology of the concave surface 121 of the oxide layer 120, thereby ensuring the effectiveness and efficiency of the etching treatment of the oxide layer 120.
[0037] For example, the etching solution may include hydrofluoric acid, as it has a good corrosive effect on the oxide layer 120. In a specific example, the etching solution is a hydrofluoric acid solution. Of course, other types of etching solutions capable of corroding the oxide layer 120 may also be used in this application, and this application is not limited thereto.
[0038] For example, the cleaning agent may include one or more of deionized water (DIW), ultrapure water (UPW), and ozone (O3). Specifically, the cleaning agent may be one or more of deionized water (DIW), ultrapure water (UPW), and ozone (O3). In a specific example, the cleaning agent may be DIW, UPW, O3, a DIW / O3 mixture, or a UPW / O3 mixture.
[0039] In some embodiments, the distance from the sprayed area of the cleaning agent on the concave surface 121 to the central axis of the wafer 100 can be less than half the radius of the wafer 100. This facilitates the formation of a larger mixing zone of the cleaning agent and the etching solution on the concave surface 121, thereby improving the etching effect of the etching solution on the oxide layer 120 and the uniformity of the treatment of the entire concave surface 121, and ultimately improving the thickness uniformity of the treated oxide layer 120.
[0040] In this embodiment, the central axis of wafer 100 is the central axis of wafer 100 in the thickness direction of substrate 110.
[0041] In actual oxidation processes, the thickness of the oxide layer 120 formed on the surface of substrate 110 typically increases gradually from the center to the edge radially along wafer 100. That is, the center point of the concave surface 121 of oxide layer 120 is substantially located near or on the central axis of wafer 100. Therefore, in some specific embodiments, the center of the cleaning agent spray area on the concave surface 121 can be located on the central axis of wafer 100. This helps to further improve the uniformity of the etching solution's treatment of the entire concave surface 121, thereby further improving the thickness uniformity of the treated oxide layer 120.
[0042] In actual processing, please refer to Figure 3 A first spray source 201 (specifically, a nozzle) can be used to spray a cleaning agent onto the concave surface 121 of the oxide layer 120. The spray area of the cleaning agent on the concave surface 121 can be controlled by the position of the first spray source 201. When the first spray source 201 sprays the cleaning agent onto the concave surface 121 of the oxide layer 120 in a vertical direction, the spray area of the cleaning agent on the concave surface 121 can be directly controlled according to the position of the first spray source 201. When the first spray source 201 does not spray the cleaning agent onto the concave surface 121 of the oxide layer 120 in a vertical direction, the position of the first spray source 201 can be adjusted according to the actual angle of the first spray source 201 spraying the cleaning agent to control the spray area of the cleaning agent on the concave surface 121 within a preset position range. Here, the vertical direction can be understood as the thickness direction of the substrate 110. Similarly, a second spray source 202 (specifically, a nozzle) can be used to spray an etching solution onto the concave surface 121 of the oxide layer 120. The spraying area of the corrosive liquid on the concave surface 121 can be controlled by the position of the second spray source 202. The specific control method can be understood by referring to the method described above for controlling the spraying area of the cleaning agent on the concave surface 121 by the position of the first spray source 201, and will not be repeated here.
[0043] In some embodiments, the first spray source 201 of the cleaning agent can move in a direction parallel to the plane of the substrate 110. This is beneficial to improve the dispersion speed and uniformity of the cleaning agent on the concave surface 121, thereby improving the uniformity of the cleaning agent's dilution of the etching solution, and further improving the etching effect of the etching solution on the oxide layer 120 and the uniformity of the treatment of the entire concave surface 121.
[0044] In actual processing, please refer to Figure 4 The first spray source 201 can be driven to move in a direction parallel to the plane of the substrate 110 by the first driving member 301 connected to the first spray source 201. Figure 4 The first driving element 301 driving the first spray source 201 to swing in the direction indicated by the dashed arrow is only one example. In some other embodiments of this application, the first driving element 301 can also drive the first spray source 201 to move in any direction parallel to the plane of the substrate 110 in any form. For example, the movement path of the first spray source 201 can be one or more combinations of a straight line, a broken line, a regular curve, and an irregular curve. In addition, the movement of the first spray source 201 can be continuous or intermittent. During the movement of the first spray source 201, the distance from the spray area of the cleaning agent on the concave surface 121 to the central axis of the wafer 100 can be controlled to be less than half the radius of the wafer 100. Exemplarily, the first driving element 301 can be a robotic arm, and the first spray source 201 can be a spray head. The robotic arm is connected to the spray head, and the movement of the robotic arm is driven by a motor, thereby driving the spray head to move in a set manner.
[0045] In some specific embodiments, the moving speed of the first spray source 201 can be less than or equal to 100 mm / s. This helps to control the spraying area of the cleaning agent on the concave surface 121, thereby improving the controllability and stability of the treatment process.
[0046] In some embodiments, the distance from the sprayed area of the etchant on the concave surface 121 to the central axis of the wafer 100 can be greater than or equal to half the radius of the wafer 100. This is beneficial to further improve the etching effect of the etchant on the oxide layer 120, thereby further improving the thickness uniformity of the treated oxide layer 120.
[0047] In some embodiments, the second spray source 202 of the etchant can move in a direction parallel to the plane of the substrate 110. This is beneficial to improve the dispersion speed and uniformity of the etchant on the concave surface 121, thereby improving the uniformity of the cleaning agent's dilution of the etchant, and further improving the etchant's effect on the oxide layer 120 and the uniformity of the treatment of the entire concave surface 121.
[0048] In actual processing, please refer to Figure 4The second spray source 202 can be driven to move along a direction parallel to the plane of the substrate 110 by a second driving member 302 connected to the second spray source 202. Figure 4 The second driving element 302 driving the second spray source 202 to swing in the direction indicated by the dashed arrow is only one example. In some other embodiments of this application, the second driving element 302 can also drive the second spray source 202 to move in any direction parallel to the plane of the substrate 110 in any form. For example, the movement path of the second spray source 202 can be one or more combinations of a straight line, a broken line, a regular curve, and an irregular curve. In addition, the movement of the second spray source 202 can be continuous or intermittent. During the movement of the second spray source 202, the distance from the spray area of the etchant on the concave surface 121 to the central axis of the wafer 100 can be controlled to be greater than or equal to half the radius of the wafer 100. Exemplarily, the second driving element 302 can be a robotic arm, and the second spray source 202 can be a nozzle. The robotic arm is connected to the nozzle, and the movement of the robotic arm is driven by a motor, thereby driving the nozzle to move in a set manner.
[0049] In some specific embodiments, the moving speed of the second spray source 202 can be less than or equal to 100 mm / s. This helps to control the spray area of the corrosive agent on the concave surface 121, thereby improving the controllability and stability of the treatment process.
[0050] In some embodiments, the first spray source 201 and the second spray source 202 can move simultaneously in a direction parallel to the plane of the substrate 110. This is beneficial for further improving the etching effect of the etchant on the oxide layer 120 and the uniformity of the treatment of the entire concave surface 121.
[0051] It is understandable that when the distance between the first spray source 201 and the center point tangent of the concave surface 121 is less than the distance between the second spray source 202 and the center point tangent of the concave surface 121, to control the contact time of the corrosive liquid with the concave surface 121 to be no later than the contact time of the cleaning agent with the concave surface 121, it is usually necessary to control the first spray source 201 to spray the liquid before the second spray source 202, which increases the complexity of the processing control. Therefore, in some embodiments, the distance between the first spray source 201 of the cleaning agent and the center point tangent of the concave surface 121 can be greater than or equal to the distance between the second spray source 202 of the corrosive liquid and the center point tangent of the concave surface 121. In this way, it is easier to control the contact time of the corrosive liquid with the concave surface 121 to be no later than the contact time of the cleaning agent with the concave surface 121. For example, the first spray source 201 and the second spray source 202 can be controlled to spray the liquid simultaneously.
[0052] In some embodiments, the distance between the first spray source 201 of the cleaning agent and the center point tangent of the concave surface 121 can be 1cm to 10cm, for example, it can be 1cm, 2cm, 3cm, 4cm, 5cm, 6cm, 7cm, 8cm, 9cm, 10cm or any value between any two of the above ranges. This facilitates appropriately increasing the spray area of the cleaning agent on the concave surface 121, thereby promoting uniform dispersion of the cleaning agent on the concave surface 121, while also better controlling the splashing of the cleaning agent.
[0053] In some embodiments, the distance between the second spray source 202 of the corrosive liquid and the tangential surface at the center of the concave surface 121 can be 1cm to 10cm, for example, it can be 1cm, 2cm, 3cm, 4cm, 5cm, 6cm, 7cm, 8cm, 9cm, 10cm or any value between any two of the above ranges. This facilitates appropriately increasing the spray area of the corrosive liquid on the concave surface 121, thereby promoting uniform dispersion of the corrosive liquid on the concave surface 121, while also better controlling the splashing of the corrosive liquid.
[0054] In some embodiments, the flow rate of the cleaning agent can be less than or equal to the flow rate of the etching solution. This can better avoid excessive dilution of the etching solution by the cleaning agent and ensure the contact time between the etching solution and the concave surface 121, thereby ensuring the effectiveness and efficiency of the etching solution in etching the oxide layer 120.
[0055] In some embodiments, the flow rate of the cleaning agent can be from 0.2 L / min to 1 L / min, for example, 0.2 L / min, 0.3 L / min, 0.4 L / min, 0.5 L / min, 0.6 L / min, 0.7 L / min, 0.8 L / min, 0.9 L / min, 1 L / min, or any value between any two of the above ranges. This ensures both the dilution effect of the cleaning agent on the corrosive solution and the rinsing effect on the corrosion products, while also avoiding waste of the cleaning agent and facilitating cost control.
[0056] In some embodiments, the flow rate of the etching solution can be from 0.2 L / min to 1 L / min, for example, 0.2 L / min, 0.3 L / min, 0.4 L / min, 0.5 L / min, 0.6 L / min, 0.7 L / min, 0.8 L / min, 0.9 L / min, 1 L / min, or any value between any two of the above ranges. This ensures both a good etching effect and efficiency on the oxide layer 120, while avoiding waste of the etching solution and facilitating cost control.
[0057] Please refer to Figure 5 After processing the wafer 100, the surface of the oxide layer 120 away from the substrate 110 forms a plane.
[0058] In some embodiments, after processing the wafer 100, the thickness uniformity of the oxide layer 120 is less than or equal to 1.5%.
[0059] The wafer processing method provided in this application effectively solves the problem of poor uniformity of oxide layer thickness on the wafer surface located in the lower region of the wafer boat during the wafer oxidation process, thereby improving wafer yield and reducing costs.
[0060] In some embodiments, after performing step S102, the wafer processing method may further include: spraying a second cleaning agent onto the surface of the oxide layer 120 away from the substrate 110 to clean the surface of the oxide layer 120.
[0061] In actual processing, the above cleaning can be performed while the wafer 100 is rotating, which improves the cleanliness and efficiency of the cleaning, and allows for direct spin-drying after cleaning the wafer 100. The second cleaning agent can be one or more of DIW, UPW, and O3. In practice, the second cleaning agent can be sprayed using the first spray source 201.
[0062] In a specific example, O3 and DIW can be sprayed sequentially from directly above the center of wafer 100 onto the surface of oxide layer 120 away from substrate 110 for cleaning. After drying, the processed wafer is obtained.
[0063] This application also provides a wafer, which is prepared using the wafer processing method described in any of the foregoing embodiments.
[0064] It is understood that the beneficial effects of the wafer processing method described in any of the foregoing embodiments are also applicable to the wafers in the embodiments of this application. Therefore, the oxide layer in the wafers in the embodiments of this application has high uniformity in thickness. In practical applications, this wafer can be used for bonding with other wafers, and ion implantation (specifically, boron implantation, phosphorus implantation, hydrogen implantation, helium implantation, hydrogen and helium implantation, etc.) can be performed on the processed wafer between bonding operations. Of course, this wafer can also be directly used to manufacture semiconductor devices.
[0065] The effects of the wafer processing method in this application will be further illustrated below with reference to several embodiments and comparative examples.
[0066] Example 1
[0067] In this embodiment, the wafer processing method includes the following steps: Step S1, providing a wafer: A silicon wafer (substrate) is oxidized at high temperature to form an oxide layer, thereby obtaining an oxide wafer (wafer); the surface of the oxide layer away from the silicon wafer is concave; the thickness uniformity of the oxide layer is U0, and the average thickness of the oxide layer is Tnm; Step S2, post-processing the oxide wafer obtained in step S1: ① Place the oxide wafer in a horizontal chuck with the oxide layer side (hereinafter referred to as the front side) facing upwards, and control the oxide wafer to rotate at a speed v; ② Spray a DIW / O3 mixture (cleaning agent) onto the front side of the oxide wafer through a first nozzle (first spray source), using an electric robotic arm to control the first nozzle to move along the direction of the substrate plane at a moving speed V1, and control the distance from the spray area of the cleaning agent on the concave surface to the central axis of the wafer to be less than half the wafer radius; spray the oxide wafer through a second nozzle (second spray source)... A hydrofluoric acid solution (etching solution) with a mass fraction of Q is sprayed onto the front side of the wafer. An electric robotic arm controls the second nozzle to move along the direction of the substrate plane at a moving speed of V2. The distance from the spraying area of the etching solution on the concave surface to the central axis of the wafer is controlled to be greater than or equal to half the wafer radius to etch the oxide layer. The first and second nozzles spray the liquid simultaneously, and the spraying time of the etching solution is ts, resulting in a processed wafer. O3 and DIW are sprayed sequentially from directly above the center of the front side of the processed wafer to clean the wafer surface. After drying, the final wafer is obtained.
[0068] The values of temperature and time, U0, T in the high-temperature oxidation process in step S1, and v, V1, V2, Q, t, distance H1 from the first nozzle to the center point of the concave surface of the oxide layer, and distance H2 from the second nozzle to the center point of the concave surface of the oxide layer in step S2 are shown in Table 1.
[0069] The wafer processing methods of Examples 2 to 9 and Comparative Examples 1 to 6 are basically the same as those of Example 1. The values of temperature and time, U0, T, v, V1, V2, Q, t, distance H1 from the first nozzle to the center point of the concave surface of the oxide layer, and distance H2 from the second nozzle to the center point of the concave surface of the oxide layer in step S2 are shown in Table 1.
[0070] The thickness uniformity U1 of the oxide layer in the wafers of each embodiment and comparative example was tested, and the test results are shown in Table 1.
[0071] Table 1
[0072] As can be seen from the data in Table 1, in Comparative Example 1, the wafer rotation rate was too low, making it difficult to ensure the effective interaction between the cleaning agent and the etching solution. This resulted in ineffective treatment of the concave surfaces of the oxide layer, and the uniformity of the oxide layer thickness after treatment was not improved, failing to meet practical application requirements (typically, an oxide layer thickness uniformity of ≤1.5%). In Comparative Examples 2 to 5, the mass fraction Q of the etching solution and the spraying time t did not meet the requirements for the oxide layer thickness uniformity U0 and average thickness T obtained after high-temperature oxidation. Furthermore, the interaction between the cleaning agent and the etching solution cannot be guaranteed, and the concave surface of the oxide layer cannot be effectively treated. The uniformity of the oxide layer thickness after treatment does not meet the requirements of practical applications. In Comparative Examples 5 and 6, since H1 is less than H2, when the first and second nozzles spray liquid simultaneously, the first nozzle is closer to the surface of the oxide layer. The cleaning agent contacts the concave surface earlier than the etching solution, which also fails to guarantee the interaction between the cleaning agent and the etching solution, and the uniformity of the oxide layer thickness after treatment does not meet the requirements of practical applications.
[0073] As can be seen from the data in Table 1, in Examples 1 to 9, the uniformity of oxide layer thickness was significantly improved after wafer processing, with the uniformity being within 1.5%, meaning the concave surface of the oxide layer was essentially transformed into a planar surface. This indicates that in this application, controlling the wafer rotation speed to 500 rpm to 1500 rpm, and simultaneously controlling the mass fraction Q of the etching solution and the spraying time t of the etching solution based on the oxide layer thickness uniformity U and the average oxide layer thickness T, results in… This ensures the effective combination of the cleaning agent and the etching solution, resulting in an increasing etching rate of the oxide layer along the wafer radial direction from the center to the edge, with the etching rate adapting to the morphology of the concave surface of the oxide layer. This allows the surface of the oxide layer away from the substrate to form a plane.
[0074] Figure 6 This is a morphological image showing the thickness distribution of the oxide layer in the wafer after high-temperature oxidation in Example 6. Figure 7 This is a morphological diagram showing the thickness distribution of the oxide layer after etching treatment in Example 6. Figure 6 and Figure 7 The comparison shows that after corrosion treatment, the uniformity of the oxide layer thickness is significantly improved, and the surface of the oxide layer is relatively smooth, basically considered as a plane.
[0075] The inventors tested the uniformity of oxide layer thickness on 200 wafers after high-temperature oxidation. A uniformity greater than 1.5% was considered unacceptable, resulting in a wafer yield of only 85.5%. After processing the unacceptable wafers using the wafer processing method described in this application, the wafer yield increased to 95.5%. In other words, this invention, by adding a post-processing step after the high-temperature oxidation process, achieves high-quality repair of concave oxide layers on wafers, significantly improving wafer yield and reducing costs.
[0076] It should be noted that the wafer processing method embodiments provided in this application and the wafer embodiments belong to the same concept; the technical features in the technical solutions described in each embodiment can be arbitrarily combined without conflict.
[0077] It should be understood that the above embodiments are exemplary and not intended to encompass all possible implementations. Various modifications and changes can be made to the above embodiments without departing from the scope of this disclosure. Similarly, the various technical features of the above embodiments can be arbitrarily combined to form other embodiments of this application that may not be explicitly described. Therefore, the above embodiments only illustrate several implementations of this application and do not limit the scope of protection of this patent application.
Claims
1. A wafer processing method, characterized in that, The method includes: A wafer is provided, the wafer including a substrate and an oxide layer on the substrate; the surface of the oxide layer away from the substrate is concave; Under the condition of wafer rotation, an etchant is sprayed onto the edge region of the concave surface, and a cleaning agent is sprayed onto the middle region of the concave surface to etch the oxide layer, so that the surface of the oxide layer away from the substrate forms a plane; the wafer rotation speed is 500 rpm to 1500 rpm; the etchant contacts the concave surface no later than the cleaning agent contacts the concave surface. The method satisfies the following relationship: ; Wherein, U represents the thickness uniformity of the oxide layer, specifically the percentage of the difference between the maximum and minimum thicknesses of the oxide layer to the average thickness of the oxide layer; T represents the average thickness of the oxide layer, in nm; Q represents the mass fraction of the etching solution; and t represents the spraying time of the etching solution, in s.
2. The wafer processing method according to claim 1, characterized in that, The Q is 1% to 10%; and / or the corrosive liquid includes hydrofluoric acid; and / or the cleaning agent includes one or more of deionized water, ultrapure water, and ozone.
3. The wafer processing method according to claim 1, characterized in that, The distance from the spray area of the cleaning agent on the concave surface to the central axis of the wafer is less than half the radius of the wafer; optionally, the center of the spray area of the cleaning agent on the concave surface is located on the central axis of the wafer.
4. The wafer processing method according to claim 3, characterized in that, The first spray source of the cleaning agent moves in a direction parallel to the plane of the substrate; optionally, the moving speed of the first spray source is less than or equal to 100 mm / s.
5. The wafer processing method according to claim 1, characterized in that, The distance from the sprayed area of the etchant on the concave surface to the central axis of the wafer is greater than or equal to half the radius of the wafer.
6. The wafer processing method according to claim 5, characterized in that, The second spray source of the corrosive liquid moves in a direction parallel to the plane of the substrate; optionally, the moving speed of the second spray source is less than or equal to 100 mm / s.
7. The wafer processing method according to claim 1, characterized in that, The distance between the first spray source of the cleaning agent and the center point tangent of the concave surface is greater than or equal to the distance between the second spray source of the corrosive liquid and the center point tangent of the concave surface; and / or, the distance between the first spray source of the cleaning agent and the center point tangent of the concave surface is 1cm to 10cm; and / or, the distance between the second spray source of the corrosive liquid and the center point tangent of the concave surface is 1cm to 10cm.
8. The wafer processing method according to claim 1, characterized in that, The flow rate of the cleaning agent is less than or equal to the flow rate of the corrosive liquid; and / or, the flow rate of the cleaning agent is 0.2 L / min to 1 L / min; and / or, the flow rate of the corrosive liquid is 0.2 L / min to 1 L / min.
9. The wafer processing method according to any one of claims 1 to 8, characterized in that, After processing the wafer, the uniformity of the oxide layer thickness is less than or equal to 1.5%.
10. A wafer, characterized in that, It is prepared by the wafer processing method according to any one of claims 1 to 9.