Groove etching method and semiconductor device

Abstract

The invention discloses a groove etching method and a semiconductor device, and the method comprises the steps: forming a plurality of barrier layers on the surface of a to-be-etched film layer, so as to form a patterned mask, and enabling the two adjacent barrier layers to have a preset interval, and enabling the preset interval to be larger than the target width of a groove; polymer films are deposited near the top of the barrier layer, so that the width of the narrowest position of a gap between every two adjacent polymer films is basically equal to the target width of the groove; etching the film layer to be etched by taking the polymer film as a mask; removing the residual polymer film; the step of depositing the polymer film, the step of etching the to-be-etched film layer and the step of removing the residual polymer film are repeated in sequence until the to-be-etched film layer is etched to the target depth to form the groove; and removing the barrier layer. According to the etching method provided by the invention, the height of the blocking structure is not increased along with the increase of the depth-to-width ratio of the groove, namely, the depth-to-width ratio of the process is not additionally increased.

Description

Technical Field

[0001] The present application relates to the field of semiconductor manufacturing technology, and in particular to a trench etching method and a semiconductor device. Background Art

[0002] As the size of semiconductor devices becomes smaller and smaller, the aspect ratio of the trench becomes higher and higher. For example, a semiconductor device with a trench width of 20nm and a trench depth of 300nm has an aspect ratio of 15:1.

[0003] For grooves with high aspect ratios, deep ultraviolet (DUV) plus multiple exposure processes can be used to form patterns. Specifically, amorphous carbon can be used as a barrier layer. However, the barrier layer of amorphous carbon is difficult to open. In addition, the barrier layer needs to be thick enough, which will further increase the aspect ratio, thereby increasing the process difficulty. Summary of the invention

[0004] In response to the above technical problems, the present application provides a trench etching method and a semiconductor device, which can improve the problem that when preparing high aspect ratio trenches using the existing DUV etching process, a sufficiently thick barrier layer needs to be made, thereby additionally increasing the aspect ratio.

[0005] In order to solve the above technical problems, in a first aspect, an embodiment of the present application provides a trench etching method, which is applied to the manufacture of semiconductor devices, comprising:

[0006] Forming a plurality of barrier layers on the surface of the film layer to be etched to form a patterned mask, wherein two adjacent barrier layers have a preset distance, and the preset distance is greater than the target width of the trench;

[0007] Depositing a polymer film near the top of the barrier layer so that the narrowest width of the gap between two adjacent polymer films is substantially equal to the target width of the groove;

[0008] Using the polymer film as a mask, etching the film layer to be etched;

[0009] Removal of residual polymer film;

[0010] Repeating the steps of depositing the polymer film, etching the film layer to be etched, and removing the residual polymer film in sequence until the film layer to be etched is etched to a target depth to form the groove;

[0011] The barrier layer is removed.

[0012] Optionally, forming a plurality of barrier layers on the surface of the film layer to be etched includes:

[0013] Depositing a metal layer on the film layer to be etched;

[0014] Etching the metal layer at the preset interval to form a patterned metal layer;

[0015] forming an isolation layer on the top surface and side surfaces of the patterned metal layer and the surface of the film layer to be etched;

[0016] The top surface of the patterned metal layer and the isolation layer on the surface of the film layer to be etched are removed, and the isolation layer on the side surface of the patterned metal layer is retained to form the barrier layer.

[0017] Optionally, the metal layer is tungsten.

[0018] Optionally, depositing a polymer film near the top of the barrier layer comprises:

[0019] The polymer film is formed by using carbon-containing gas, and the polymer film is a carbon chain layer.

[0020] Optionally, the carbon-containing gas includes a fluorocarbon gas.

[0021] Optionally, the carbon-containing gas further includes an auxiliary starting gas, wherein a flow ratio of the carbon-fluorine gas to the auxiliary starting gas is 6 to 10.

[0022] Optionally, in the step of forming the polymer film using a carbon-containing gas, the flow rate of the carbon-containing gas is 150-250 sccm; the power of the RF power supply is 800W-1200W, and the power of the bias power supply is 150W-250W.

[0023] Optionally, in the step of etching the film layer to be etched using the polymer film as a mask, the gas used for etching includes a fluorine-containing gas.

[0024] Optionally, the gas used for etching further includes an auxiliary ignition gas, and the flow ratio of the fluorine-containing gas to the auxiliary ignition gas is 1 to 10.

[0025] Optionally, the fluorine-containing gas includes NF3, CH3F, CHF3, and the auxiliary starting gas includes Ar, wherein the flow ratio of NF3, CH3F, CHF3 and Ar is (1.3-1.5):(0.9-1.1):(0.8-1.0):1.

[0026] Optionally, in the step of etching the film layer to be etched using the polymer film as a mask, the power of the radio frequency power supply is 800W-1200W, and the power of the bias power supply is 595W-695W.

[0027] Optionally, the removing of the residual polymer film comprises:

[0028] The polymer film is removed using an oxygen-containing gas.

[0029] Optionally, the oxygen-containing gas includes oxygen, the oxygen flow rate is 450-550sccm, and the power of the radio frequency power supply is 400-600W.

[0030] In a second aspect, an embodiment of the present application provides a semiconductor device, wherein a groove of the semiconductor device is manufactured by the groove etching method described in any of the above embodiments.

[0031] As described above, the groove etching method of the present application is to make a polymer film on the barrier layer so that the minimum gap width between adjacent polymer films on the barrier layer is substantially equal to the target width of the groove, and then etch, remove the residual polymer film after etching to a certain depth, and repeat the steps of depositing the polymer film, etching the film layer to be etched, and removing the residual polymer film until the film layer to be etched is etched to the target depth to form the final groove. The groove etching method of this embodiment does not need to use EUV equipment, and can achieve the production of high aspect ratio grooves by multiple cycles of etching through DUV equipment, and the height of the barrier structure (barrier layer + polymer film) of this method will not increase due to the increase of the trench aspect ratio, that is, the aspect ratio of the process will not be increased, and the process requirements of advanced DRAM can be met. It should be noted that, in theory, the grooves produced by this method can obtain a sufficiently large aspect ratio by increasing the number of etchings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application. In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor.

[0033] Figure 1 It is a schematic diagram of a process of a trench etching method provided in an embodiment of the present application;

[0034] Figure 2 It is a schematic diagram of a process for manufacturing a barrier layer provided in an embodiment of the present application;

[0035] Figure 3a-3h It is a structural schematic diagram corresponding to each step of a trench etching method provided in an embodiment of the present application.

[0036] The realization of the purpose, functional features and advantages of this application will be further described in conjunction with the embodiments and with reference to the accompanying drawings. The above-mentioned drawings have shown clear embodiments of this application, which will be described in more detail later. These drawings and textual descriptions are not intended to limit the scope of the concept of this application in any way, but to illustrate the concept of this application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0037] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0038] It should be noted that, in this article, the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element. In addition, components, features, and elements with the same name in different embodiments of the present application may have the same meaning or different meanings, and their specific meanings need to be determined by their explanation in the specific embodiment or further combined with the context of the specific embodiment.

[0039] It should be further understood that the terms "comprising" and "including" indicate the presence of the described features, steps, operations, elements, components, items, kinds, and / or groups, but do not exclude the presence, occurrence or addition of one or more other features, steps, operations, elements, components, items, kinds, and / or groups. The terms "or", "and / or", "including at least one of the following", etc. used in this application may be interpreted as inclusive, or mean any one or any combination. For example, "including at least one of the following: A, B, C" means "any one of the following: A; B; C; A and B; A and C; B and C; A and B and C", and for another example, "A, B or C" or "A, B and / or C" means "any one of the following: A; B; C; A and B; A and C; B and C; A and B and C". Exceptions to this definition will only occur when the combination of elements, functions, steps or operations is inherently mutually exclusive in some way.

[0040] It should be understood that although the terms first, second, third, etc. may be used herein to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this document, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, as used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless otherwise indicated in the context.

[0041] It should be understood that the orientations or positional relationships indicated by terms such as "top", "bottom", "up", "down", "vertical", and "horizontal" are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present application and simplifying the description. They do not indicate or imply that the device referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0042] See also Figure 1 , Figure 1 It is a schematic flow chart of a trench etching method provided in an embodiment of the present application. The trench etching method may include S110-S160.

[0043] S110, forming a plurality of barrier layers on the surface of the film layer to be etched to form a patterned mask, wherein two adjacent barrier layers have a preset spacing, and the preset spacing is greater than the target width of the trench.

[0044] The film layer to be etched is formed on the surface of a substrate 10, and the substrate 10 may be a silicon substrate, a silicon-containing substrate, an epitaxial silicon substrate, a silicon-on-insulator substrate, or a substrate composed of other suitable materials. A plurality of barrier layers 20 are formed on the surface of the etched film layer to form a patterned mask, wherein a preset spacing D1 is provided between two adjacent barrier layers 20, and the preset spacing D1 is greater than the target width D0 of the trench. For example, the above barrier layer array may be formed by a method of first depositing and then etching.

[0045] As an example, see Figure 2 , Figure 2 1 is a flow chart of a method for manufacturing a barrier layer provided in an embodiment of the present application. The method for manufacturing a barrier layer may include S111-S114.

[0046] S111, depositing a metal layer on the film layer to be etched.

[0047] A metal layer 201 is deposited on the film layer to be etched of the substrate 10. Figure 3a For example, the material of the metal layer can be tungsten (W), aluminum (Al), titanium (Ti), tantalum (Ta), niobium (Nb), molybdenum (Mo), copper (Cu), etc. The deposition method of the metal layer 201 includes but is not limited to physical vapor deposition, chemical vapor deposition, magnetron sputtering, thermal evaporation deposition, etc.

[0048] S112, etching the metal layer at a preset interval to form a patterned metal layer.

[0049] For example, see Figure 3b , a photoresist layer can be formed on the metal layer 201, and then the metal layer 201 is etched at a preset spacing D1 to form a patterned metal layer. It can be understood that the patterned metal layer includes a plurality of metal lines 21, and a first groove 202 is formed between adjacent metal lines 21. Specifically, a patterning process can be performed through the photoresist layer, and the pattern of the photoresist layer can be transferred to the metal layer 201 below, so that a patterned metal layer can be formed in the metal layer 201, and the photoresist layer can be removed after the etching is completed.

[0050] S113, forming an isolation layer on the top surface and side surfaces of the patterned metal layer and the surface of the film layer to be etched.

[0051] In order to improve the stability of the patterned metal layer, an isolation layer can be used to protect the patterned metal layer. For example, see Figure 3c , a titanium nitride film 203 can be formed on the bottom and side surfaces of the first trench 202 and the top surface of the metal layer 201. As an example, the titanium nitride film 203 can be formed by an atomic layer deposition (ALD) process. TiN has the advantages of corrosion resistance, heat resistance, and high barrier properties, and can effectively improve the stability of the metal layer 21.

[0052] S114, removing the top surface of the patterned metal layer and the isolation layer on the surface of the film layer to be etched, and retaining the isolation layer on the side of the patterned metal layer to form a barrier layer.

[0053] For example, see Figure 3d After the titanium nitride film 203 is formed, the titanium nitride film 203 on the bottom of the first trench 202 and the titanium nitride film 203 on the top of the metal layer 201 can be etched back by atomic layer etching (ALE), and finally the sidewalls 22 are formed on both sides of the metal line 21, and the barrier layer 20 (including the metal line 21 and the sidewalls 22) is completed. Preferably, the metal layer 201 is tungsten, which has better bonding with titanium nitride, and the two can be used together.

[0054] S120, depositing a polymer film near the top of the barrier layer so that the narrowest width of the gap between two adjacent polymer films is substantially equal to the target width of the groove.

[0055] For example, see Figure 3e , a polymer film 30 can be deposited on the top surface of the barrier layer 20 and the side surface near the top, so that the narrowest width D2 of the gap between two adjacent polymer films 30 is substantially equal to the target width D0 of the groove. It should be noted that the polymer film 30 is formed by a compound with a relatively long carbon chain and is in a solid form. For example, a perfluoroalkane with more than 8 carbon atoms (or part of F is replaced by H), or a solid polymer including more carbon atoms, and the polymer may also contain double bonds.

[0056] It should be noted that the polymer film 30 will be distributed on the surface of the entire substrate 10 during growth, but it is most likely to grow along the surface with a larger curvature. In addition, the deeper the first groove 202 is, the thinner the deposited polymer film 30 is. Therefore, the polymer film 30 is mainly deposited near the top of the barrier layer 20, and is basically ellipsoidal. The polymer film 30 at other locations is very thin, which is not drawn in the figure and is not a key parameter to be controlled in this application. When the width D2 of the narrowest part of the gap between two adjacent polymer films 30 is basically equal to the target groove width D0, the growth of the polymer film 30 is stopped. Specifically, the deposition thickness can be controlled according to the growth time and gas flow rate.

[0057] For example, a carbon-containing gas can be used to form a polymer film, and the polymer film is a carbon chain layer. As an example, the carbon-containing gas can include a fluorocarbon gas, and the carbon-containing gas can also include an auxiliary ignition gas, wherein the flow ratio of the fluorocarbon gas to the auxiliary ignition gas is 6 to 10. More specifically, the fluorocarbon gas includes CH3F, and the auxiliary ignition gas includes Ar, wherein the flow ratio of CH3F to Ar is 6 to 10. By combining the gases with this ratio, the uniformity of the polymer film can be improved. For example, the flow rate of Ar is 25 sccm, and the flow rate of CH3F can be 150-250 sccm.

[0058] As an example, the flow rate of the carbon-containing gas may be 150-250 sccm, the power of the RF power source may be 800 W-1200 W, and the power of the bias power source may be 150 W-250 W. Specifically, the deposition parameters and deposition time may be specifically selected according to the designed thickness of the polymer film 30 .

[0059] For example, the polymer film 30 may be deposited on the top surface and the side surface near the top of the barrier layer 20 by plasma enhanced chemical vapor deposition (PECVD) process using Ar with a flow rate of 25 sccm as a carrier gas and CH3F with a flow rate of 200 sccm as a reaction gas.

[0060] S130, using the polymer film as a mask, etching the film layer to be etched.

[0061] For example, please continue to see Figure 3e After the polymer film 30 is formed, the polymer film 30 can be used as a mask to etch the second groove 40 on the film layer to be etched on the substrate 10. During etching, the etching time can be controlled according to the loss of the polymer film 30 to prevent the width D2 of the narrowest part between adjacent polymer films 30 from being too large, resulting in the second groove 40 being too wide or the sidewall of the second groove 40 being seriously tilted.

[0062] In one embodiment, the gas used for etching may include a fluorine-containing gas, and the gas used for etching may also include an auxiliary ignition gas, and the flow ratio of the fluorine-containing gas to the auxiliary ignition gas is 1 to 10. More specifically, the fluorine-containing gas may include NF3, CH3F, CHF3, and the auxiliary ignition gas may include Ar, wherein the flow ratio of NF3, CH3F, CHF3 and Ar is (1.3-1.5): (0.9-1.1): (0.8-1.0): 1. The etching morphology of the sidewall of the second trench 40 can be better controlled by the gas flow combination with this ratio.

[0063] In this embodiment, NF3 and CHF3 can etch the dielectric layer and silicon of the substrate 10. CH3F can protect the barrier layer 20 and prolong the etching time to increase the depth of each etching.

[0064] As an example, in the etching process, with the flow rate of the carrier gas as 50sccm as a reference, the flow rate of NF3 can be 65-75sccm, the flow rate of CH3F can be 45-55sccm, and the flow rate of CHF3 can be 40-50sccm; the power of the RF power supply can be 800W-1200W, and the power of the bias power supply can be 595W-695W. In this embodiment, the bias power supply selects a higher power, which is easy to form a deep groove. Specifically, the etching parameters and etching time can be specifically selected according to the real-time change of the minimum width D2 between adjacent polymer films 30 during the etching process.

[0065] S140, removing the residual polymer film.

[0066] For example, see Figure 3f After the second groove 40 is etched, since the surface of the polymer film 30 is etched at the same time, the minimum width D2 between adjacent polymer films 30 also changes. In order to improve the subsequent etching accuracy, the residual polymer film 30 needs to be removed.

[0067] For example, an oxygen-containing gas may be used to remove the polymer film. Taking the oxygen-containing gas as an example, during the process, the flow rate of oxygen may be 450-550 sccm, and the power of the RF power supply may be 400-600 W. Oxygen may oxidize the polymer film 30 under the action of the RF power supply, and the generated gas may be extracted through the exhaust system.

[0068] S150, sequentially repeating the steps of depositing a polymer film, etching the film layer to be etched, and removing the residual polymer film until the film layer to be etched is etched to a target depth to form a final groove.

[0069] For example, see Figure 3g After the second groove 40 is etched through the aforementioned steps, the steps S120-S140 can be repeated. Each time the steps are repeated, the second groove 40 can be advanced into the substrate 10, and the depth becomes deeper, but the groove width D0 remains unchanged. After multiple cycles, the depth of the second groove 40 can be etched to the target depth H0, thereby forming a final groove.

[0070] S160: removing the barrier layer.

[0071] For example, see Figure 3h After the second trench 40 is etched to a target depth H0, the barrier layer 20 may be removed. As an example, the barrier layer 20 may be removed by wet etching.

[0072] The groove etching method of this embodiment is to form a polymer film 30 on the barrier layer 20 so that the minimum gap width D2 between adjacent polymer films 30 on the barrier layer 20 is substantially equal to the target groove width D0, and then perform etching. After etching a certain depth (second groove 40), remove the remaining polymer film 30, and repeat the steps of depositing the polymer film 30, etching the film layer to be etched (i.e., etching the first groove 40), and removing the remaining polymer film 30 until the film layer to be etched is etched to the target depth H0 to form the final groove. The groove etching method of this embodiment does not require the use of EUV equipment, and can achieve the production of high aspect ratio grooves by performing multiple cycles of etching with DUV equipment, and the height of the barrier structure (barrier layer 20 + polymer film 30) will not increase due to the increase in the groove aspect ratio, that is, the aspect ratio of the process will not be increased, and the process requirements of advanced DRAM can be met. It should be noted that, in theory, the grooves produced by this method can obtain a sufficiently large aspect ratio by increasing the number of etchings.

[0073] The present application is further described below with reference to specific embodiments.

[0074] In this embodiment, after the wafer with the barrier layer 20 (the thickness of W is approximately 600A, and the thickness of TiN is approximately 200A) is transferred into the etching chamber, an adsorption voltage is applied to the electrostatic chuck in the etching chamber to adsorb the wafer, and then 8T helium gas is introduced into the back of the wafer before the ignition etching step.

[0075] Etching mainly consists of three steps, namely, depositing (Dep) the polymer film 30, etching (Etch) the second groove 40, and removing (Flush) the remaining polymer film 30, and the above steps are cycled 30 times, and the final groove depth is about 2000A, and the aspect ratio is about 10:1. The specific parameters used in each step are shown in Table 1 below. After etching is completed, the helium supply to the back of the wafer is stopped, and then the voltage of the electrostatic chuck is stopped, and finally the wafer is transferred out of the etching chamber.

[0076] Table 1. Key process parameters for each step in the etching process

[0077]

[0078] An embodiment of the present application also provides a semiconductor device, wherein a groove of the semiconductor device is manufactured by the groove etching method described in the above embodiments.

[0079] Regarding the principle and process of manufacturing the grooves on the semiconductor device of this embodiment, please refer to the description of the groove etching method in the aforementioned embodiment of the present application, which will not be repeated here.

[0080] The above is a detailed introduction to a trench etching method and a semiconductor device provided by the present application. This article uses specific examples to illustrate the principles and implementation methods of the present application. It should be noted that in the present application, the descriptions of various embodiments have different emphases. For parts that are not described or recorded in detail in a particular embodiment, please refer to the relevant descriptions of other embodiments.

[0081] The above are only preferred embodiments of the present application, and the patent scope of the present application is not limited thereto. The various technical features of the technical solution of the present application can be arbitrarily combined. In order to make the description concise, not all possible combinations of the various technical features in the above embodiments are described. Any equivalent structure or equivalent process transformation made using the contents of the specification and drawings of this application, or directly or indirectly used in other related technical fields, as long as there is no contradiction in the combination of these technical features, are equally included in the patent protection scope of the present application.

Claims

1. A trench etching method, applied to the manufacture of semiconductor devices, characterized in that: include: Forming a plurality of barrier layers on the surface of the film layer to be etched to form a patterned mask, wherein two adjacent barrier layers have a preset distance, and the preset distance is greater than the target width of the trench; Depositing a polymer film near the top of the barrier layer so that the narrowest width of the gap between two adjacent polymer films is substantially equal to the target width of the groove; Using the polymer film as a mask, etching the film layer to be etched; Removal of residual polymer film; Repeating the steps of depositing the polymer film, etching the film layer to be etched, and removing the residual polymer film in sequence until the film layer to be etched is etched to a target depth to form the groove; The barrier layer is removed.

2. The trench etching method according to claim 1, characterized in that: The step of forming a plurality of barrier layers on the surface of the film layer to be etched comprises: Depositing a metal layer on the film layer to be etched; Etching the metal layer at the preset interval to form a patterned metal layer; forming an isolation layer on the top surface and side surfaces of the patterned metal layer and the surface of the film layer to be etched; The top surface of the patterned metal layer and the isolation layer on the surface of the film layer to be etched are removed, and the isolation layer on the side surface of the patterned metal layer is retained to form the barrier layer.

3. The trench etching method according to claim 2, characterized in that: The metal layer is tungsten.

4. The trench etching method according to claim 1, characterized in that: The step of depositing a polymer film near the top of the barrier layer comprises: The polymer film is formed by using carbon-containing gas, and the polymer film is a carbon chain layer.

5. The trench etching method according to claim 4, characterized in that: The carbon-containing gas includes fluorocarbon gas.

6. The trench etching method according to claim 5, characterized in that: The carbon-containing gas also includes an auxiliary ignition gas, wherein the flow ratio of the carbon-fluorine gas to the auxiliary ignition gas is 6 to 10.

7. The trench etching method according to claim 4, characterized in that: In the step of forming the polymer film by using the carbon-containing gas, the flow rate of the carbon-containing gas is 150-250 sccm; the power of the radio frequency power supply is 800W-1200W, and the power of the bias power supply is 150W-250W.

8. The trench etching method according to claim 1, characterized in that: In the step of etching the film layer to be etched using the polymer film as a mask, the gas used for etching includes a fluorine-containing gas.

9. The trench etching method according to claim 8, characterized in that: The gas used for etching also includes an auxiliary ignition gas, and the flow ratio of the fluorine-containing gas to the auxiliary ignition gas is 1 to 10.

10. The trench etching method according to claim 9, characterized in that: The fluorine-containing gas includes NF3, CH3F, and CHF3, and the auxiliary starting gas includes Ar, wherein the flow ratio of NF3, CH3F, CHF3 and Ar is (1.3-1.5):(0.9-1.1):(0.8-1.0):

1.

11. The trench etching method according to claim 1, characterized in that: In the step of etching the film layer to be etched using the polymer film as a mask, the power of the radio frequency power supply is 800W-1200W, and the power of the bias power supply is 595W-695W.

12. The trench etching method according to claim 1, characterized in that: The removing of the residual polymer film comprises: The polymer film is removed using an oxygen-containing gas.

13. The trench etching method according to claim 12, characterized in that: The oxygen-containing gas includes oxygen, the oxygen flow rate is 450-550sccm, and the power of the radio frequency power supply during the process is 400-600W.

14. A semiconductor device, characterized in that: The trench of the semiconductor device is made by the trench etching method according to any one of claims 1 to 13.

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