Preparation method of convex region window
By depositing dielectric and protective films on the raised structure and controlling the etching depth and selectivity, the problem of insufficient alignment accuracy between the window and the raised structure was solved, and high-precision window fabrication and process compatibility were achieved.
Patent Information
- Application Number
- CN202511135885.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-13
- Publication Date
- 2025-11-11
AI Technical Summary
In the prior art, when creating a window on a raised structure, it is difficult to ensure precise alignment between the window and the raised structure, resulting in insufficient positional accuracy, and the fabrication process is incompatible with standard CMOS processes.
By sequentially depositing dielectric and protective films on a substrate structure, controlling the etching depth and selectivity of the protective film, etching the protective film first and then the dielectric film, a high-precision window is formed, which is compatible with standard CMOS processes.
It enables the fabrication of high-precision windows, improves positional accuracy and process compatibility, and is suitable for the precise fabrication of similar structures.
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Figure CN120933154A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, and in particular to a method for fabricating a raised region window. Background Technology
[0002] In the fabrication process of semiconductor devices, it is necessary to prepare windows in special locations, such as the top part of some protruding structures that need to have windows.
[0003] In existing technologies, window regions are typically fabricated using photolithography. This involves defining a specific mask and then using photolithography and etching to form the window at the designated location. In this process, the accuracy of the window's position depends on the resolution of the photolithography machine. However, when creating windows on raised structures, the alignment between the window region and the raised structure becomes problematic. If the alignment precision exceeds the alignment capability of the photolithography machine, the alignment between the window and the raised structure cannot be guaranteed. In other words, existing fabrication processes may not be able to meet the required positional accuracy of the window. Summary of the Invention
[0004] One objective of the first aspect of this invention is to provide a method for preparing a raised area window that can ensure the positional accuracy of the window.
[0005] A further objective of this invention is to improve process compatibility.
[0006] This invention provides a method for preparing a raised area window, comprising: Prepare a matrix structure, the matrix structure comprising a base layer and at least one protrusion structure located on the top surface of the base layer; A dielectric film and a protective film are sequentially deposited on the substrate structure; The protective film layer is etched under a first etching condition to thin it to below the top of the dielectric film layer of the protrusion structure. Under the first etching condition, the etching selectivity ratio of the protective film layer to the dielectric film layer is greater than 1:1. The dielectric film is etched under the second etching condition such that the distance between the top of the dielectric film and the top of the protrusion is the target height difference. Under the second etching condition, the etching selectivity ratio of the dielectric film and the protective film is greater than 5:1. Remove the protective film layer to form a window in the top region of the raised structure.
[0007] Optionally, the material of the dielectric film layer is one or more of silicon dioxide, silicon nitride, polycrystalline silicon, and silicon oxynitride.
[0008] Optionally, the protective film layer is one or more of photoresist, silicon nitride, silicon dioxide, silicon oxynitride, and carbon-based hard mask.
[0009] Optionally, under the first etching conditions, the distance between the top of the protective film layer and the top of the protruding structure after etching is less than the target height difference.
[0010] Optionally, the etching depth uniformity under the first etching condition is less than 5%.
[0011] Optionally, the average etching depth fluctuation under the first etching condition is less than 5%.
[0012] Optionally, in the step of removing the protective film layer, the protective film layer is removed by dry etching or wet etching, and the etching selectivity ratio of the protective film layer to the dielectric film layer is greater than 10:1.
[0013] Optionally, the step of removing the protective film layer may be followed by a cleaning step to remove etching residues.
[0014] Optionally, the steps for preparing a matrix structure include: Provide a substrate; A dielectric layer is deposited on the substrate; At least one of the protrusion structures is formed on the dielectric layer.
[0015] According to one aspect of the present invention, the fabrication method involves first depositing a dielectric film and a protective film on the surface of a substrate structure with a protruding structure, then etching the protective film to expose the end of the protruding structure, then etching the dielectric film to form a window at the end of the protruding structure, and finally removing the protective film. This method of forming a window by etching can accurately fabricate windows with high positional accuracy, and the fabrication process is compatible with standard CMOS processes. It can be widely used in the precise fabrication of similar structures and has broad application prospects.
[0016] Furthermore, by controlling the etching depth of the protective film, it is ensured that the bottom of the area to be etched in the dielectric film is lower than the top surface of the protective film during etching. On the one hand, the higher protective film can act as an etching mask, improving the steepness of the window edge or preventing lateral etching diffusion of the dielectric film. On the other hand, it can also prevent the higher protective film from being exhausted prematurely, thus protecting the material below during the etching of the dielectric film. In addition, given a fixed etching selectivity ratio between the protective film and the dielectric film, the thickness of the protective film can be used as an auxiliary criterion for determining the endpoint of the dielectric film etching.
[0017] Furthermore, by controlling the uniformity of the etching depth of the protective film, the thickness difference between the protective film and the dielectric film can be accurately controlled, ensuring that the depth of the etched window is stable and controllable, thereby improving the positional accuracy of the formed window. Attached Figure Description
[0018] Figure 1 This is a flowchart of a method for preparing a raised area window according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a method for preparing a raised area window according to an embodiment of the present invention; Figure label: 10-Base layer, 11-Substrate, 21-Dielectric layer, 31-Protrusion structure, 41-Dielectric film layer, 51-Protective film layer, 42-Window. Detailed Implementation
[0019] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.
[0020] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or there may be an intermediate component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application's specification are for illustrative purposes only and do not represent the only possible implementation.
[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0022] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature and the second feature are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0023] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items.
[0024] Figure 1 This is a flowchart illustrating a method for preparing a raised area window 42 according to an embodiment of the present invention. Figure 1 As shown, in one embodiment, the method for preparing the raised area window 42 includes: Step S100: Prepare a substrate structure, the substrate structure including a base layer 10 and at least one protrusion structure 31 located on the top surface of the base layer 10, see [link to relevant documentation]. Figure 2 (a) in the middle; Step S200: A dielectric film 41 and a protective film 51 are sequentially deposited on the substrate structure. (See below) Figure 2 (b) and (c) in the middle; Step S300: Under the first etching condition, the protective film layer 51 is etched to thin it to below the top of the dielectric film layer 41 of the protrusion structure 31. See [link to relevant documentation]. Figure 2 In (d), under the first etching condition, the etching selectivity ratio of the protective film layer 51 and the dielectric film layer 41 is greater than 1:1; Step S400: Etch the dielectric film layer 41 under the second etching condition, such that the distance between the top of the dielectric film layer 41 and the top of the protrusion structure 31 is the target height difference h. (See [reference]) Figure 2 In (e), under the second etching condition, the etching selectivity ratio of the dielectric film layer 41 and the protective film layer 51 is greater than 5:1; Step S500: Remove the protective film layer 51 to form a window 42 in the top region of the raised structure 31. See [link to relevant documentation] Figure 2 (f) in the middle.
[0025] The protrusion structure 31 in step S100 is a functional structure in a semiconductor device for which the volume of the exposed portion at the top needs to be controlled. The specific material and function of the protrusion structure 31 are not limited here. For example, the protrusion structure 31 can be the light-emitting pixel unit of a micro-LED, made of gallium nitride, or the photosensitive or active region of a photodiode, using materials such as InGaAs, GaN, or Ge. The protrusion structure 31 can also be the detection region of a photodetector, etc., without limitation. The shape of the protrusion structure 31 can be conical, cylindrical, elongated, rectangular, or irregular, without limitation.
[0026] In step S200, the dielectric film layer 41 is made of one or more of silicon dioxide, silicon nitride, polycrystalline silicon, and silicon oxynitride, and the protective film layer 51 is made of one or more of photoresist, silicon nitride, silicon dioxide, silicon oxynitride, and carbon-based hard mask.
[0027] Both steps S400 and S500 can employ dry etching or wet etching processes. It is important to note that the selection of the protective film layer 51 and the dielectric film layer 41 must meet the above-mentioned etching selectivity requirements. This ensures that when etching the protective film layer 51, the dielectric film layer 41 is not etched or its etching rate is lower than that of the protective film layer 51. Conversely, when etching the dielectric film layer 41, its etching rate must be greater than that of the protective film layer 51. For example, when etching the protective film layer 51 under the first etching condition, the etching selectivity ratio of the dielectric film layer 41 to the protective film layer 51 can be 6:1, 8:1, 10:1, or 20:1. In specific implementations, for example, the material of the dielectric film 41 is silicon dioxide, the material of the protective film 51 is photoresist, the photoresist is etched by oxygen plasma etching, and the silicon dioxide is etched by fluorine-based reactive ion etching; or the material of the dielectric film 41 is silicon nitride, and high-density plasma etching is performed under CHF3 / O2 or SF6 / O2 mixed gas, the protective film 51 is a carbon-based hard mask, and plasma dry etching is performed under O2 / Ar mixed atmosphere.
[0028] In step S500, the material removal method varies depending on the material of the protective film layer 51. For example, when the protective film layer 51 is photoresist, it can be removed using O2 plasma dry etching or NMP solution. When the protective film layer 51 is silicon dioxide, it can be removed using plasma etching under a CF4 / O2 etching atmosphere. The material removal process in step S500 can be the same as that in step S300. It should be noted that the purpose of step S500 is to remove the protective film layer 51 and retain the dielectric film layer 41 formed in step S400. Therefore, the etching selectivity ratio still needs to be considered. Here, the etching selectivity ratio of the protective film layer 51 to the dielectric film layer 41 can be greater than 10:1, for example, an etching selectivity ratio of 15:1, 20:1, or 30:1.
[0029] The fabrication method of this embodiment involves first depositing a dielectric film layer 41 and a protective film layer 51 sequentially on the surface of a substrate structure with a protrusion structure 31, then etching the protective film layer 51 to expose the end of the protrusion structure 31, and then etching the dielectric film layer 41 to form a window 42 at the end of the protrusion structure 31. Finally, the protective film layer 51 is removed. This method of forming the window 42 by etching can accurately fabricate the window 42 with high positional accuracy, and the fabrication process is compatible with standard CMOS processes. It can be widely used in the precise fabrication of similar structures and has broad application prospects.
[0030] In a further embodiment, the distance d between the top of the protective film layer 51 after etching under the first etching condition and the top of the protrusion structure 31 is less than the target height difference h.
[0031] Here, the target height difference h is a value determined according to the design target. In this embodiment, by controlling the etching depth of the protective film layer 51, it is ensured that when etching the dielectric film layer 41, the bottom end of the area to be etched in the dielectric film layer 41 is lower than the upper surface of the protective film layer 51. On the one hand, the higher protective film layer 51 can act as an etching mask to improve the steepness of the window 42 edge or prevent the lateral etching diffusion of the dielectric film layer 41. On the other hand, it can also prevent the higher protective film layer 51 from being exhausted prematurely, thus protecting the material below during the etching of the dielectric film layer 41. In addition, when the etching selectivity ratio of the protective film layer 51 to the dielectric film layer 41 is determined, the thickness of the protective film layer 51 can be used as an auxiliary criterion for determining the etching endpoint of the dielectric film layer 41.
[0032] In a further embodiment, the etching depth uniformity under the first etching condition is less than 5%. Etching depth uniformity is understood as the ratio of the difference between the maximum etching depth and the average etching depth of the protective film layer 51 to the average etching depth being less than 5%, and the ratio of the difference between the minimum etching depth and the average etching depth of the protective film layer 51 to the average etching depth being greater than -5%. The fluctuation of the average etching depth under the first etching condition is less than 5%. The fluctuation of the average etching depth is understood as the maximum difference between the average etching depths during each fabrication process of the raised region window 42 being less than 5%.
[0033] This embodiment controls the uniformity of the etching depth of the protective film layer 51, thereby accurately controlling the thickness difference between the protective film layer 51 and the dielectric film layer 41, ensuring that the depth of the etched window 42 is stable and controllable, and thus improving the positional accuracy of the formed window 42.
[0034] Furthermore, by controlling the fluctuation of the average etching depth of the protective film layer 51, the stability of process repeatability can be achieved.
[0035] In a further embodiment, a cleaning step is included after step S500 to remove etching residues. For example, when silicon dioxide is used for the dielectric film 41 and photoresist is used for the protective film 51, the etching and removal of the dielectric film 41 are performed using O2 plasma dry etching, and the protective film 51 is etched using CHF3, O2, and Ar dry etching. During cleaning, NMP solution is used for immersion cleaning to dissolve incompletely ashed photoresist residues and remove polymer impurities. Subsequently, at least three running rinses with deionized water (DI water) are performed to thoroughly remove the NMP solution and dissolved residues. Next, cleaning is performed using a first standard cleaning solution (SC1), which is a cleaning solution composed of ammonia, hydrogen peroxide, and deionized water in a 1:1:5 ratio. This step is mainly used to remove particles, organic residues, and some metal contaminants. Then, cleaning is performed using a second standard cleaning solution (SC2), which is a mixture of hydrochloric acid, hydrogen peroxide, and deionized water in a 1:1:6 ratio, to remove metal ion contaminants such as aluminum and iron ions. Finally, a thorough rinse with deionized water is performed, followed by drying with nitrogen to prevent water spots and residual chemical deposits, ensuring a clean surface.
[0036] In one embodiment, the preparation of the matrix structure in step S100 includes the following steps: S1. Provide a substrate 11; S2. Deposit dielectric layer 21 on substrate 11; S3. At least one protrusion structure 31 is formed on the dielectric layer 21.
[0037] In this embodiment, a silicon wafer is used as the substrate 11, and the dielectric layer 21 is made of silicon dioxide. The substrate 11 and the dielectric layer 21 are the base layer 10 mentioned above. The protrusion structure 31 is made of gallium nitride and is conical. The protrusion structure 31 is arranged in an array. The protrusion structure 31 can be obtained by photolithography and etching.
[0038] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.
Claims
1. A method for preparing a raised area window, characterized in that, include: Prepare a matrix structure, the matrix structure comprising a base layer and at least one protrusion structure located on the top surface of the base layer; A dielectric film and a protective film are sequentially deposited on the substrate structure; The protective film layer is etched under a first etching condition to thin it to below the top of the dielectric film layer of the protrusion structure. Under the first etching condition, the etching selectivity ratio of the protective film layer to the dielectric film layer is greater than 1:
1. The dielectric film is etched under the second etching condition such that the distance between the top of the dielectric film and the top of the protrusion is the target height difference. Under the second etching condition, the etching selectivity ratio of the dielectric film and the protective film is greater than 5:
1. Remove the protective film layer to form a window in the top region of the raised structure.
2. The preparation method according to claim 1, characterized in that, The dielectric film is made of one or more of silicon dioxide, silicon nitride, polycrystalline silicon, and silicon oxynitride.
3. The preparation method according to claim 1, characterized in that, The protective film layer is one or more of photoresist, silicon nitride, silicon dioxide, silicon oxynitride, and carbon-based hard mask.
4. The preparation method according to claim 1, characterized in that, Under the first etching conditions, the distance between the top of the protective film layer and the top of the protruding structure after etching is less than the target height difference.
5. The preparation method according to claim 1, characterized in that, The etching depth uniformity under the first etching condition is less than 5%.
6. The preparation method according to claim 1, characterized in that, The average etching depth fluctuates by less than 5% under the first etching condition.
7. The preparation method according to claim 1, characterized in that, In the step of removing the protective film layer, the protective film layer is removed by dry etching or wet etching, and the etching selectivity ratio of the protective film layer to the dielectric film layer is greater than 10:
1.
8. The preparation method according to claim 1, characterized in that, The step of removing the protective film layer is followed by a cleaning step to remove etching residues.
9. The preparation method according to any one of claims 1-8, characterized in that, The steps for preparing a matrix structure include: Provide a substrate; A dielectric layer is deposited on the substrate; At least one of the protrusion structures is formed on the dielectric layer.