Shallow trench isolation structure, trench manufacturing method and semiconductor device

Abstract

The invention relates to a shallow trench isolation structure, a trench manufacturing method and a semiconductor device. The method comprises the following steps: forming a patterned hard mask on a substrate; forming a polymer on the side wall of the hard mask; performing dry etching on the substrate to form a groove; the polymer is bombarded and diffused by plasma in the dry etching process, and is adhered to the surface of the adjacent substrate; the polymer is removed; and filling silicon oxide in the groove after the polymer is removed to form the shallow groove isolation structure. The polymer formed on the side wall of the hard mask is bombarded by the plasma downwards during dry etching, so that the polymer is diffused, transferred downwards and adhered to the surface of the adjacent substrate, the side wall of the trench is protected, and the shallow trench isolation structure with a small side wall angle is obtained.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing, and in particular to a method for manufacturing a shallow trench isolation structure, a method for manufacturing a trench, and a semiconductor device. Background Technology

[0002] The sidewall angle α of a typical shallow trench isolation (STI) structure is usually 80 to 85 degrees. See also... Figure 1 The sidewall angle α of an STI (Surface Mount Technology) refers to the angle between the STI and the horizontal plane. For some special devices, it is necessary to form an STI with a smaller sidewall angle. Summary of the Invention

[0003] Therefore, it is necessary to provide a manufacturing method for a shallow trench isolation structure that can form a smaller sidewall angle.

[0004] A method for manufacturing a shallow trench isolation structure includes: forming a patterned hard mask on a substrate; forming a polymer on the sidewalls of the hard mask; dry etching the substrate to form trenches; the polymer being bombarded and diffused by plasma during the dry etching process, and adhering back to the adjacent substrate surface; removing the polymer; and filling the trenches after polymer removal with silicon oxide to form a shallow trench isolation structure.

[0005] In the above-mentioned method for manufacturing shallow trench isolation structures, the polymer formed on the sidewall of the hard mask is bombarded downward by plasma during dry etching, thus diffusing and transferring downward, and adhering back to the adjacent substrate surface to form protection for the trench sidewall, thereby obtaining a shallow trench isolation structure with a small sidewall angle.

[0006] In one embodiment, the thickness of the polymer formed on the sidewalls of the hard mask is determined according to the designed sidewall angle of the shallow trench isolation structure; the straighter the designed sidewall angle, the greater the thickness of the polymer.

[0007] In one embodiment, the polymer contains fluorine and carbon elements.

[0008] In one embodiment, the step of forming the polymer on the sidewall of the hard mask is to form the polymer using gas deposition containing carbon and fluorine elements.

[0009] In one embodiment, the polymer contains fluorine, carbon, and hydrogen.

[0010] In one embodiment, the step of forming the polymer on the sidewall of the hard mask is to form the polymer using a gas deposition process containing carbon, fluorine, and hydrogen elements.

[0011] In one embodiment, the hard mask is made of silicon nitride.

[0012] In one embodiment, the thickness of the polymer is no greater than 1000 Å.

[0013] In one embodiment, the sidewall angle of the shallow trench isolation structure is 45 to 75 degrees, and the sidewall angle is the angle between the sidewall of the shallow trench isolation structure and the upper surface of the trench isolation structure.

[0014] In one embodiment, the width of the top of the shallow trench isolation structure is 0.2 to 5 micrometers.

[0015] In one embodiment, the step of forming a polymer on the sidewall of the hard mask includes forming a polymer covering the hard mask and the substrate.

[0016] It is also necessary to provide a method for manufacturing the trench.

[0017] A method for manufacturing a trench includes: forming a patterned hard mask on a substrate; forming a polymer on the sidewalls of the hard mask; dry etching the substrate to form a trench; and the polymer being bombarded and diffused by plasma during the dry etching process, and then adhering back to an adjacent substrate surface.

[0018] In the above-mentioned trench manufacturing method, the polymer formed on the sidewall of the hard mask is bombarded downward by plasma during dry etching, so it diffuses and transfers downward, and sticks back to the adjacent substrate surface, forming protection for the trench sidewall, thereby obtaining a trench with a smaller sidewall angle.

[0019] In one embodiment, the thickness of the polymer formed on the sidewalls of the hard mask is determined according to the designed sidewall angle of the trench; the straighter the designed sidewall angle, the greater the thickness of the polymer.

[0020] In one embodiment, the polymer contains fluorine and carbon elements.

[0021] In one embodiment, the step of forming the polymer on the sidewall of the hard mask is to form the polymer using gas deposition containing carbon and fluorine elements.

[0022] In one embodiment, the polymer contains fluorine, carbon, and hydrogen.

[0023] In one embodiment, the step of forming the polymer on the sidewall of the hard mask is to form the polymer using a gas deposition process containing carbon, fluorine, and hydrogen elements.

[0024] In one embodiment, the hard mask is made of silicon nitride.

[0025] In one embodiment, the thickness of the polymer is no greater than 1000 Å.

[0026] In one embodiment, the sidewall angle of the trench is 45 to 75 degrees, and the sidewall angle is the angle between the sidewall of the trench and the upper surface of the trench isolation structure.

[0027] In one embodiment, the width of the top of the trench is 0.2 to 5 micrometers.

[0028] In one embodiment, the step of forming a polymer on the sidewall of the hard mask includes forming a polymer covering the hard mask and the substrate.

[0029] It is also necessary to provide a method for manufacturing the trench structure.

[0030] A method for manufacturing a trench structure includes: forming a patterned hard mask on a substrate; forming a polymer on the sidewalls of the hard mask; dry etching the substrate to form a trench; the polymer being bombarded and diffused by plasma during the dry etching process, and adhering back to an adjacent substrate surface; removing the polymer; and filling the trench after polymer removal with a target material to form a trench structure.

[0031] In the above-mentioned method for manufacturing trench structures, the polymer formed on the sidewall of the hard mask is bombarded downward by plasma during dry etching, thus diffusing and transferring downward, and adhering back to the adjacent substrate surface, forming protection for the trench sidewall, thereby obtaining a trench structure with a smaller sidewall angle.

[0032] In one embodiment, the thickness of the polymer formed on the sidewalls of the hard mask is determined according to the designed sidewall angle of the trench structure; the straighter the designed sidewall angle, the greater the thickness of the polymer.

[0033] In one embodiment, the polymer contains fluorine and carbon elements.

[0034] In one embodiment, the step of forming the polymer on the sidewall of the hard mask is to form the polymer using gas deposition containing carbon and fluorine elements.

[0035] In one embodiment, the polymer contains fluorine, carbon, and hydrogen.

[0036] In one embodiment, the step of forming the polymer on the sidewall of the hard mask is to form the polymer using a gas deposition process containing carbon, fluorine, and hydrogen elements.

[0037] In one embodiment, the hard mask is made of silicon nitride.

[0038] In one embodiment, the thickness of the polymer is no greater than 1000 Å.

[0039] In one embodiment, the sidewall angle of the trench structure is 45 to 75 degrees, and the sidewall angle is the angle between the sidewall of the trench structure and the upper surface of the trench isolation structure.

[0040] In one embodiment, the width of the top of the trench structure is 0.2 to 5 micrometers.

[0041] In one embodiment, the step of forming a polymer on the sidewall of the hard mask includes forming a polymer covering the hard mask and the substrate.

[0042] It is also necessary to provide a semiconductor device comprising a shallow trench isolation structure formed by the manufacturing method of the shallow trench isolation structure described in any of the foregoing embodiments, or comprising a trench structure formed by the manufacturing method of the trench structure described in any of the foregoing embodiments, or the semiconductor device having a trench formed by the manufacturing method of the trench described in any of the foregoing embodiments. Attached Figure Description

[0043] To better describe and illustrate embodiments and / or examples of the inventions disclosed herein, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed inventions, the currently described embodiments and / or examples, or the best mode of these inventions as currently understood.

[0044] Figure 1 This is a schematic diagram of an exemplary STI structure.

[0045] Figure 2 This is a flowchart of a method for manufacturing a shallow trench isolation structure according to an embodiment of this application.

[0046] Figure 3 This is a schematic diagram of the semiconductor structure after step S210 is completed in one embodiment of this application.

[0047] Figure 4 This is a schematic diagram of the semiconductor structure after step S220 is completed in one embodiment of this application.

[0048] Figure 5 This is a schematic diagram of the semiconductor structure after step S230 is completed in one embodiment of this application.

[0049] Figure 6 This is a schematic diagram of the etching process in step S230 of one embodiment of this application.

[0050] Figure 7 This is a schematic diagram of the semiconductor structure after step S240 is completed in one embodiment of this application.

[0051] Figure 8 This is a schematic diagram of the semiconductor structure after step S250 is completed in one embodiment of this application.

[0052] Figure 9 This is a microscope image of the semiconductor structure after step S210 is completed in one embodiment of this application.

[0053] Figure 10 This is a microscope image of the semiconductor structure after step S220 is completed in one embodiment of this application.

[0054] Figure 11 This is a microscope image of the semiconductor structure after step S230 is completed in one embodiment of this application.

[0055] Figure 12 This is a flowchart of a method for manufacturing a trench according to one embodiment of this application.

[0056] Figure 13 This is a flowchart of a method for manufacturing a trench structure according to one embodiment of this application. Detailed Implementation

[0057] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0059] It should be understood that when a component or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other components or layers, it may be directly on, adjacent to, connected to, or coupled to other components or layers, or there may be intervening components or layers. Conversely, when a component is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other components or layers, there are no intervening components or layers. The term "connection" in this specification, if referring to the transmission of electrical signals or data between connected circuits, modules, units, etc., should be understood as "electrical connection," "communication connection," etc. It should be understood that although the terms first, second, third, etc., may be used to describe various components, parts, areas, layers, and / or portions, these components, parts, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one component, part, area, layer, or portion from another component, part, area, layer, or portion. Therefore, without departing from the teachings of this invention, the first element, component, region, layer or portion discussed below may be represented as a second element, component, region, layer or portion.

[0060] 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.

[0061] 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 will be understood that “at least one” means one or more, and “a plurality” means two or more. “At least a portion of an element” means part or all of an element. It should also be understood that the terms “compose” and / or “comprising,” when used in this specification, identify the presence of the stated 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.

[0062] Embodiments of the invention are described herein with reference to cross-sectional views that serve as schematic diagrams of ideal embodiments (and intermediate structures). Thus, variations in the shape shown can be anticipated due to, for example, manufacturing techniques and / or tolerances. Therefore, embodiments of the invention should not be limited to the specific shapes of the regions shown herein, but include shape deviations due to, for example, manufacturing processes. For example, implantation regions shown as rectangular typically have rounded or curved features at their edges and / or implantation concentration gradients, rather than a binary change from implantation regions to non-implantation regions. Similarly, the buried regions formed by implantation can result in some implantation in the region between the buried region and the surface traversed during implantation. Therefore, the regions shown in the figures are substantially schematic, and their shapes are not intended to show the actual shapes of the regions of the device and are not intended to limit the scope of the invention.

[0063] This application proposes a method for manufacturing a shallow trench isolation structure (STI). By depositing a polymer layer before STI etching, the trench sidewalls can be protected during the subsequent STI etching process, resulting in an STI with a smaller sidewall angle (the angle between the STI and the horizontal plane). Engineers can also control the sidewall angle of the formed STI more accurately.

[0064] Figure 2 This is a flowchart of a method for manufacturing a shallow trench isolation structure according to an embodiment of this application, including the following steps:

[0065] S210 forms a patterned hard mask on a substrate.

[0066] In one embodiment of this application, the substrate 310 includes a semiconductor substrate, the material of which may be undoped single-crystal silicon, doped single-crystal silicon, silicon-on-insulator (SOI), silicon-on-insulator stacked (SSOI), silicon-on-insulator stacked (S-SiGeOI), silicon-on-insulator (SiGeOI), and germanium-on-insulator (GeOI), etc., and may also be at least one of the following materials: Si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP, or other III / V compound semiconductors. Figure 3 In the embodiment shown, the substrate 310 is made of monocrystalline silicon.

[0067] In one embodiment of this application, a silicon oxide layer (pad oxide) is first formed as a buffer layer before forming the hard mask on the substrate 310, and then the hard mask is formed on the silicon oxide layer. In one embodiment of this application, the hard mask is made of silicon nitride.

[0068] In one embodiment of this application, the patterned hard mask includes coating a hard mask with photoresist, then exposing it using an active area photomask, and after development, using the remaining photoresist 340 as an etching mask to etch and form a hard mask 330 and a silicon oxide layer 320, with etching stopping at the substrate 310. In one embodiment of this application, the etching employs a dry etching process.

[0069] S220 forms a polymer on the sidewalls of a hard mask.

[0070] In one embodiment of this application, a polymer 350 is deposited as a protective layer on the sidewall of the hard mask 330. By selecting a suitable polymer material, the polymer 350 is made to diffuse when bombarded by plasma in a subsequent dry etching step and then re-adhere to the surface of the adjacent substrate 310.

[0071] In one embodiment of this application, polymer 350 contains fluorine and carbon elements; further, polymer 350 contains fluorine, carbon, and hydrogen elements, and its material can be represented as (C x H y F z ) n The polymer 350 can be formed by selecting a suitable deposition gas; specifically, it is formed by depositing a gas containing carbon and fluorine elements and / or a gas containing carbon, fluorine, and hydrogen elements. In one embodiment of this application, CH2F2 / C4F8 / C4F6 (C x H y F z / C x F y A certain thickness of fluorocarbon polymer is deposited using FC gases, such as polymer 350.

[0072] See Figure 4 In one embodiment of this application, the polymer 350 deposited in step S220 is also formed on the upper surface of the substrate 310 and the photoresist 340.

[0073] S230, dry etching of the substrate to form trenches, polymer re-adhesion to the adjacent substrate surface.

[0074] Reference Figure 5 After being bombarded by the plasma of dry etching, the polymer 350 diffuses along with the plasma as an etchant and re-adheres onto the adjacent surface of the substrate 310—including the sidewall surface of the trench 311. Figure 6 This is a schematic diagram of the etching process in step S230 of one embodiment of this application.

[0075] S240, removes polymers.

[0076] In one embodiment of this application, the polymer 350 and photoresist 340 are removed by dry and wet methods. The structure after removing the polymer 350 and photoresist 340 is as follows. Figure 7 As shown.

[0077] S250 involves filling the trench with silicon oxide to form a shallow trench isolation structure.

[0078] In one embodiment of this application, silicon oxide is deposited into trench 311 to form a shallow trench isolation (STI) 360. See also... Figure 8 The sidewall angle of the shallow trench isolation structure 360 ​​is T2, which is the angle between the sidewall of the shallow trench isolation structure 360 ​​and the upper surface of the trench isolation structure 360.

[0079] The aforementioned method for manufacturing shallow trench isolation structures involves polymer 350 formed on the sidewalls of the hard mask 330 undergoing dry etching. During this etching process, the polymer 350 is bombarded downwards by plasma, causing it to diffuse and transfer downwards, adhering back to the adjacent substrate 310 surface. This forms protection for the sidewalls of the trench 311, resulting in a shallow trench isolation structure 360 ​​with a small sidewall angle. Furthermore, by controlling the thickness of the polymer 350 formed in step S220, the sidewall angle of the shallow trench isolation structure 360 ​​can be adjusted, demonstrating broad application prospects. Moreover, the manufacturing process of this shallow trench isolation structure is relatively simple and easy to control.

[0080] In one embodiment of this application, the thickness of the polymer 350 formed on the sidewall of the hard mask 330 in step S220 (hereinafter referred to as T1) is determined based on the designed sidewall angle of the shallow trench isolation structure 360. The designed sidewall angle is the designed value of the angle between the sidewall of the shallow trench isolation structure 360 ​​and the upper surface of the trench isolation structure 360. The straighter the designed sidewall angle (i.e., the closer it is to 90 degrees), the thicker T1 is. Therefore, by adjusting (reasonably designing) the value of T1, the sidewall angle of the shallow trench isolation structure 360 ​​can be made stable and controllable.

[0081] Furthermore, the amount of polymer 350 re-adhesion in step S230 can be adjusted by regulating the bombardment power of T1 and the dry etching in step S230. The thicker T1 and the weaker the bombardment power, the less re-adhesion occurs, resulting in a straighter trench angle T2. The longer the etching time in step S230, the deeper the trench 311 becomes, thereby achieving controllable angle and depth of the shallow trench isolation structure 360.

[0082] In one embodiment of this application, T1 is no greater than 1000 Å. The corresponding sidewall angle of the shallow trench isolation structure 360 ​​is 45 degrees to 75 degrees.

[0083] In one embodiment of this application, the width of the top of the shallow trench isolation structure 360 ​​is 0.2 micrometers to 5 micrometers.

[0084] In one embodiment of this application, the thickness of the photoresist 340 formed in step S210 ranges from 0.3 micrometers to 2 micrometers, and the critical dimension (CD) of the photoresist 340 ranges from 0.25 micrometers to 10 micrometers.

[0085] Figure 9 This is a microscope image of the semiconductor structure after step S210 is completed in one embodiment of this application. Figure 10 This is a microscope image of the semiconductor structure after step S220 is completed in one embodiment of this application. Figure 11 This is a microscope image of the semiconductor structure after step S230 is completed in one embodiment of this application.

[0086] In one embodiment of this application, the photoresist 340 can also be removed before the polymer 350 is formed. That is, after the hard mask 330 is patterned in step S210 and before step S220, the photoresist 340 is removed first, and then the polymer 350 is formed.

[0087] This application provides a semiconductor device including a shallow trench isolation structure formed by the manufacturing method of the shallow trench isolation structure described in any of the foregoing embodiments.

[0088] This application provides a method for manufacturing a trench. Figure 12 This is a flowchart of a method for manufacturing a trench according to an embodiment of this application, including the following steps:

[0089] S410 forms a patterned hard mask on a substrate.

[0090] In one embodiment of this application, the substrate 310 includes a semiconductor substrate, the material of which may be undoped single-crystal silicon, doped single-crystal silicon, silicon-on-insulator (SOI), silicon-on-insulator stacked (SSOI), silicon-on-insulator stacked (S-SiGeOI), silicon-on-insulator (SiGeOI), and germanium-on-insulator (GeOI), etc., and may also be at least one of the following materials: Si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP, or other III / V compound semiconductors. Figure 3 In the embodiment shown, the substrate 310 is made of monocrystalline silicon.

[0091] In one embodiment of this application, a silicon oxide layer (pad oxide) is first formed as a buffer layer before forming the hard mask on the substrate 310, and then the hard mask is formed on the silicon oxide layer. In one embodiment of this application, the hard mask is made of silicon nitride.

[0092] In one embodiment of this application, patterning includes coating a hard mask with photoresist, then exposing it using an active area photomask, and after development, using the remaining photoresist 340 as an etching mask to etch and form a hard mask 330 and a silicon oxide layer 320, with etching stopping at the substrate 310. In one embodiment of this application, the etching employs a dry etching process.

[0093] S420 forms a polymer on the sidewalls of a hard mask.

[0094] In one embodiment of this application, a polymer 350 is deposited as a protective layer on the sidewall of the hard mask 330. By selecting a suitable polymer material, the polymer 350 is made to diffuse when bombarded by plasma in a subsequent dry etching step and then re-adhere to the surface of the adjacent substrate 310.

[0095] In one embodiment of this application, polymer 350 contains fluorine and carbon elements; further, polymer 350 contains fluorine, carbon, and hydrogen elements, which can be represented as (C x H y F z ) n The polymer 350 can be formed by selecting a suitable deposition gas; specifically, it is formed by depositing a gas containing carbon and fluorine elements and / or a gas containing carbon, fluorine, and hydrogen elements. In one embodiment of this application, CH2F2 / C4F8 / C4F6 (C x H y F z / C x F y FC gases, etc., are used to deposit fluorocarbon polymers of a certain thickness.

[0096] See Figure 4 In one embodiment of this application, the polymer 350 deposited in step S420 is also formed on the upper surface of the substrate 310 and the photoresist 340.

[0097] S430, dry etching of the substrate to form trenches, polymer re-adhesion to the adjacent substrate surface.

[0098] Reference Figure 5 After being bombarded by the plasma of dry etching, the polymer 350 diffuses along with the plasma as an etchant and re-adheres onto the adjacent surface of the substrate 310—including the sidewall surface of the trench 311. Figure 6 This is a schematic diagram of the etching process in step S430 of one embodiment of this application.

[0099] In the above-mentioned trench manufacturing method, the polymer 350 formed on the sidewall of the hard mask 330 is bombarded downward by plasma during dry etching, so it diffuses and transfers downward, and sticks back to the surface of the adjacent substrate 310, forming protection for the sidewall of the trench 311, thereby obtaining a trench 311 with a smaller sidewall angle.

[0100] This application provides a semiconductor device having a trench 311 formed by the trench manufacturing method according to any of the foregoing embodiments.

[0101] This application provides a method for manufacturing a trench structure. Figure 13 This is a flowchart of a method for manufacturing a trench structure according to an embodiment of this application, including the following steps:

[0102] S410 forms a patterned hard mask on a substrate.

[0103] In one embodiment of this application, the substrate 310 includes a semiconductor substrate, the material of which may be undoped single-crystal silicon, doped single-crystal silicon, silicon-on-insulator (SOI), silicon-on-insulator stacked (SSOI), silicon-on-insulator stacked (S-SiGeOI), silicon-on-insulator (SiGeOI), and germanium-on-insulator (GeOI), etc., and may also be at least one of the following materials: Si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP, or other III / V compound semiconductors. Figure 3 In the embodiment shown, the substrate 310 is made of monocrystalline silicon.

[0104] In one embodiment of this application, a silicon oxide layer (pad oxide) is first formed as a buffer layer before forming the hard mask on the substrate 310, and then the hard mask is formed on the silicon oxide layer. In one embodiment of this application, the hard mask is made of silicon nitride.

[0105] In one embodiment of this application, patterning includes coating a hard mask with photoresist, then exposing it using an active area photomask, and after development, using the remaining photoresist 340 as an etching mask to etch and form a hard mask 330 and a silicon oxide layer 320, with etching stopping at the substrate 310. In one embodiment of this application, the etching employs a dry etching process.

[0106] S420 forms a polymer on the sidewalls of a hard mask.

[0107] In one embodiment of this application, a polymer 350 is deposited as a protective layer on the sidewall of the hard mask 330. By selecting a suitable polymer material, the polymer 350 is made to diffuse when bombarded by plasma in a subsequent dry etching step and then re-adhere to the surface of the adjacent substrate 310.

[0108] In one embodiment of this application, polymer 350 contains fluorine and carbon elements; further, polymer 350 contains fluorine, carbon, and hydrogen elements, which can be represented as (C x H y F z ) n The polymer 350 can be formed by selecting a suitable deposition gas; specifically, it is formed by depositing a gas containing carbon and fluorine elements and / or a gas containing carbon, fluorine, and hydrogen elements. In one embodiment of this application, CH2F2 / C4F8 / C4F6 (C x H y F z / C x F y FC gases, etc., are used to deposit fluorocarbon polymers of a certain thickness.

[0109] See Figure 4 In one embodiment of this application, the polymer 350 deposited in step S420 is also formed on the upper surface of the substrate 310 and the photoresist 340.

[0110] S430, dry etching of the substrate to form trenches, polymer re-adhesion to the adjacent substrate surface.

[0111] Reference Figure 5 After being bombarded by the plasma of dry etching, the polymer 350 diffuses along with the plasma as an etchant and re-adheres onto the adjacent surface of the substrate 310—including the sidewall surface of the trench 311. Figure 6 This is a schematic diagram of the etching process in step S430 of one embodiment of this application.

[0112] S440, removes polymers.

[0113] In one embodiment of this application, the polymer 350 and photoresist 340 are removed by dry and wet methods. The structure after removing the polymer 350 and photoresist 340 is as follows. Figure 7 As shown.

[0114] S450, fill the trench with the target material to form a trench structure.

[0115] The target material can be silicon nitride, silicon dioxide, etc.

[0116] In the above-mentioned method for manufacturing the trench structure, the polymer 350 formed on the sidewall of the hard mask 330 is bombarded downward by plasma during dry etching, and thus diffuses and transfers downward, sticking back to the surface of the adjacent substrate 310, forming protection for the sidewall of the trench 311, thereby obtaining a trench structure with a smaller sidewall angle.

[0117] It should be understood that although the steps in the flowchart of this application are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowchart of this application may include multiple steps or multiple stages, which are not necessarily completed at the same time, but may be executed at different times, and the execution order of these steps or stages is not necessarily sequential, but may be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0118] In the description of this specification, references to terms such as "some embodiments," "other embodiments," and "ideal embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0119] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features of the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0120] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for manufacturing a shallow trench isolation structure, characterized in that, include: Form a patterned hard mask on the substrate; A polymer is formed on the sidewalls of the hard mask; The substrate is dry-etched to form trenches; The polymer is bombarded and diffused by plasma during dry etching, and then re-adheres to the adjacent substrate surface. Remove the polymer; Silicon oxide is filled into the trench after the polymer has been removed to form a shallow trench isolation structure.

2. The manufacturing method of the shallow trench isolation structure according to claim 1, characterized in that, The thickness of the polymer formed on the sidewalls of the hard mask is determined according to the design sidewall angle of the shallow trench isolation structure. The straighter the design sidewall angle, the greater the thickness of the polymer.

3. The manufacturing method of the shallow trench isolation structure according to claim 1, characterized in that, The polymer contains fluorine and carbon, or the polymer contains fluorine, carbon, and hydrogen.

4. The manufacturing method of the shallow trench isolation structure according to claim 3, characterized in that, The step of forming the polymer on the sidewall of the hard mask is to deposit the polymer using a gas containing carbon and fluorine elements and / or a gas containing carbon, fluorine and hydrogen elements.

5. The manufacturing method of the shallow trench isolation structure according to claim 1, characterized in that, The width of the top of the shallow trench isolation structure is 0.2 to 5 micrometers.

6. The method for manufacturing the shallow trench isolation structure according to claim 1, characterized in that, The hard mask is made of silicon nitride.

7. The method for manufacturing the shallow trench isolation structure according to any one of claims 1-6, characterized in that, The thickness of the polymer is no greater than 1000 Å.

8. The method for manufacturing the shallow trench isolation structure according to any one of claims 1-6, characterized in that, The sidewall angle of the shallow trench isolation structure is 45 to 75 degrees, and the sidewall angle is the angle between the sidewall of the shallow trench isolation structure and the upper surface of the trench isolation structure.

9. A method for manufacturing a trench, characterized in that, include: Form a patterned hard mask on the substrate; A polymer is formed on the sidewalls of the hard mask; The substrate is dry-etched to form trenches; The polymer is bombarded and diffused by plasma during dry etching, and then re-adheres to the adjacent substrate surface.

10. A semiconductor device, characterized in that, This includes a shallow trench isolation structure formed by the manufacturing method of the shallow trench isolation structure according to any one of claims 1-8, or the semiconductor device having a trench formed by the manufacturing method of the trench according to claim 9.

Images