Photoresist removal method, photoresist cleaning agent, semiconductor structure and preparation method

Abstract

The invention provides a photoresist removal method, a photoresist cleaning agent, a semiconductor structure and a preparation method. The photoresist removal method comprises the following steps: providing a semiconductor substrate; hardened photoresist remains on the surface of the semiconductor substrate; silica sol mixed with activated molecules is arranged on the photoresist, so that the photoresist is softened under a specified temperature condition; wherein the silica sol is used as a carrier for activating molecules; and removing the silica sol and the softened photoresist on the surface of the semiconductor substrate by using an ultraviolet cleaning technology. The method for removing the photoresist can reduce the loss of the substrate material caused in the process of removing the photoresist to a certain extent.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of semiconductor manufacturing process technology, and in particular to a photoresist removal method, a photoresist cleaning agent, a semiconductor structure and a manufacturing method. Background Art

[0002] In the semiconductor manufacturing process, photoresist can be used as a temporary mask material to define and protect specific areas on the semiconductor substrate during the photolithography process to achieve precise pattern transfer. After completing the photolithography and subsequent etching or deposition processes, there may be residual photoresist on the substrate surface. If it is not removed, it will not only affect the accuracy and reliability of subsequent processes, but may also cause the performance of the manufactured semiconductor device to degrade or fail. Therefore, it is necessary to use a stripping process to remove the residual photoresist to ensure that the substrate surface is clean and pollution-free.

[0003] In some cases, due to the influence of the previous process, the surface of the photoresist will harden and it is difficult to remove it using conventional stripping methods. Wet cleaning methods are required, such as using SPM (Sulfuric Peroxide Mixture) as a cleaning solution to remove the hardened photoresist.

[0004] However, since the cleaning solution used in wet cleaning is usually oxidizing or corrosive to a certain extent, it is easy to corrode the substrate material during the photoresist removal process, thereby causing loss of the substrate material. Summary of the invention

[0005] In view of this, multiple embodiments of the present application are dedicated to providing a photoresist removal method, a photoresist cleaning agent, a semiconductor structure and a preparation method, which can reduce the loss of substrate material caused by the photoresist removal process to a certain extent.

[0006] One embodiment of the present application provides a method for removing photoresist, which includes: providing a semiconductor substrate; hardened photoresist remaining on the surface of the semiconductor substrate; arranging a silica sol mixed with activated molecules on the photoresist to soften the photoresist under specified temperature conditions; wherein the silica sol serves as a carrier of the activated molecules; and using ultraviolet light cleaning technology to remove the silica sol and the softened photoresist on the surface of the semiconductor substrate.

[0007] In some embodiments, the activating molecule comprises: benzotriazole and alcoholamine.

[0008] In some embodiments, the specified temperature condition is a temperature range of 130°C to 200°C.

[0009] In some embodiments, the step of disposing a silica sol mixed with activated molecules on the photoresist to soften the photoresist under specified temperature conditions includes: uniformly coating the silica sol on the photoresist; adding benzotriazole and amine to the silica sol; and heating the coating area of ​​the silica sol to reach the specified temperature conditions.

[0010] In some embodiments, the step of heating the silica sol coating area to reach the specified temperature condition includes: irradiating the silica sol coating area with infrared light; wherein the duration of the infrared light irradiation falls within the range of 0.5h to 1h.

[0011] In some embodiments, in the silica sol mixed with benzotriazole and olamine, the proportions of the components are: benzotriazole, 0.05% to 0.2%; olamine, 0.02% to 0.05%; and the rest is silica sol.

[0012] In some embodiments, residual organic matter is removed from the surface of the semiconductor substrate during the process of removing the silica sol and softened photoresist using ultraviolet cleaning technology; the photoresist removal method further includes: removing the organic matter using a wet cleaning process.

[0013] One embodiment of the present application provides a method for preparing a semiconductor structure, which includes the steps in the method for removing photoresist as described in any of the above embodiments.

[0014] One embodiment of the present application provides a semiconductor structure, which is prepared by the semiconductor structure preparation method described in the above embodiment.

[0015] One embodiment of the present application provides a photoresist cleaning agent, which is applied to the photoresist removal method as described in any of the aforementioned embodiments; the photoresist cleaning agent is composed of the activated molecules and silica sol; wherein the activated molecules include benzotriazole and alcohol amine; the photoresist cleaning agent includes: benzotriazole, 0.05% to 0.2%; alcohol amine, 0.02% to 0.05%; the rest is silica sol.

[0016] The present application provides a plurality of embodiments, using silica sol mixed with activated molecules to soften the residual hardened photoresist under specified temperature conditions, and using ultraviolet cleaning technology to remove the silica sol and the softened photoresist together. The unexpected effect is that the silica sol is used as a carrier of the activated molecules, the cleaning method is relatively mild, and the silica sol can protect the substrate surface, making it difficult to damage the substrate surface during the degumming process, thereby reducing the substrate material loss caused in the process of removing the photoresist to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of a method for removing photoresist provided in accordance with one embodiment of the present application.

[0018] Figure 2 A schematic diagram of the operation of a method for removing photoresist provided in one embodiment of the present application.

[0019] Figure 3 A schematic diagram of the molecular structure of benzotriazole provided for one embodiment of the present application.

[0020] Figure 4 A schematic diagram of a nucleophilic reaction in a method for removing photoresist provided in one embodiment of the present application. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0022] In the present application, the drawings are not necessarily drawn to scale, and local features may be enlarged or reduced to more clearly show details of the local features.

[0023] Unless otherwise stated, all technical and scientific terms used in this application have the same meaning as those generally understood by those skilled in the art of the technical field of this application. The terms used in this application are only for the purpose of describing the specific implementation mode and are not intended to limit the scope of this application. The term "and / or" used in this application includes any and all combinations of one or more related listed items. The singular forms of "a kind of", "above" and "the" used in this application implementation mode and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0024] In the description of the present application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0025] In the related art, the hardened photoresist remaining on the surface of the substrate is usually removed by wet cleaning, for example, using a sulfuric acid-hydrogen peroxide mixture (SPM) as a wet cleaning solution for degumming. SPM can be made by mixing concentrated sulfuric acid (H2SO4) and hydrogen peroxide (H2O2) in a certain proportion. SPM has extremely strong oxidizing and high temperature characteristics, and can quickly oxidize and decompose the photoresist at high temperatures, converting it into a soluble compound, making it easy to remove.

[0026] The process of removing photoresist by wet cleaning usually requires immersion in a cleaning solution or ultrasonic cleaning. Taking SPM as an example, first, the substrate with hardened photoresist remaining on the surface is immersed in a preheated SPM solution. After a period of immersion, the photoresist will be oxidized and decomposed. Then the substrate is removed from the SPM solution and rinsed thoroughly with deionized water, or ultrasonic cleaning is used to remove the residual SPM solution and decomposition products.

[0027] However, since the cleaning liquid used in the wet cleaning method, such as SPM, ozone aqueous solution, etc., has strong oxidizing properties, this strong oxidizing property is not only effective for photoresist, but may also corrode the material on the substrate or the deposited thin film layer, resulting in the loss of substrate material during the wet cleaning process. For example, for some metal materials and their oxides, the strong oxidizing property of SPM may cause these materials to be corroded or lost.

[0028] Therefore, it is necessary to provide a method for removing photoresist, which can reduce the loss of substrate material caused in the process of removing photoresist to a certain extent.

[0029] See also Figure 1 and Figure 2 One embodiment of the present application provides a method for removing a photoresist, and the method for removing a photoresist may include the following steps.

[0030] S110: providing a semiconductor substrate; hardened photoresist remains on the surface of the semiconductor substrate.

[0031] In this embodiment, the semiconductor base may include only a substrate as the basis of the semiconductor device, or may include a semiconductor structure composed of a substrate and other components disposed on the substrate, such as a gate, a contact hole, etc. Specifically, the substrate is not only a carrier of various active layers and other structures, but also directly affects the electrical performance and reliability of the semiconductor device. For example, the material of the substrate may include silicon (Si), gallium arsenide (GaAs), silicon carbide (SiC) or gallium nitride (GaN), etc., which may be selected according to actual application requirements.

[0032] In this embodiment, due to the influence of the process such as exposure, development, etching, ion implantation, etc., the surface of the photoresist will harden and remain on the surface of the semiconductor substrate, affecting the reliability of the subsequent process. For example, the photoresist after exposure usually undergoes steps such as pre-bake (soft bake) and post-exposure bake (post-exposure bake) to stabilize the photolithography pattern and remove the solvent. However, if the temperature, time or exposure dose in the process is not properly controlled, the remaining photoresist part will be overheated, resulting in further cross-linking reaction, making its molecular structure more dense, hardened and difficult to peel off. For another example, in the plasma etching or deposition process, the residual photoresist may come into contact with the reaction gas or plasma, and these chemical reactions will form a layer of insoluble carbonized film on its surface, thereby aggravating the hardening.

[0033] S120: placing a silica sol mixed with activation molecules on the photoresist to soften the photoresist under a specified temperature condition.

[0034] In the present embodiment, the activated molecule may include molecules that enter an excited state or have a high reactivity by absorbing energy, to promote the carrying out of a specific chemical reaction or physical process in a semiconductor manufacturing process. Specifically, for example, in processes such as ion implantation, thin film deposition, etching, etc., the activated molecule can accelerate the reaction rate or reduce the reaction temperature. In the present embodiment, the activated molecule can be used for a nucleophilic reaction with a hardened photoresist under a specified temperature condition to soften the photoresist.

[0035] In this embodiment, silica sol is used as a carrier of activated molecules. Silica sol (Silica Sol-Gel) is a colloidal solution composed of nano-sized silicon dioxide (SiO2) particles dispersed in water or solvent. Since SiO2 in silica sol is combined with a large amount of water and hydroxyl groups, it can be expressed as SiO2·nH2O. Silica sol has a large specific surface area, good mechanical strength and chemical inertness, is odorless and non-toxic, and is resistant to high temperatures (1500°C to 1600°C), and has stable and mild properties. In addition, the swelling of silica sol in solvents is also low and can be ignored.

[0036] In this embodiment, the specified temperature condition is used as a reaction condition for the nucleophilic reaction between the activated molecule and the hardened photoresist. Specifically, the specified temperature condition can be a specific temperature value or a temperature value range. For example, the specified temperature condition can be 120°C or 140°C, or a temperature range of 120°C to 220°C. In some embodiments, the specific temperature value or temperature value range of the specified temperature condition can be determined by the material type, property, state, etc. of the activated molecule used and the photoresist to be removed.

[0037] In this embodiment, the silica sol mixed with the activated molecules is arranged on the photoresist, and the activated molecules can be mixed in the silica sol solution in advance, that is, a cleaning agent composed of the activated molecules and the silica sol is prepared in advance, and then the cleaning agent is evenly coated on the surface of the photoresist. Of course, in some embodiments, the activated molecules and the silica sol can also be arranged on the surface of the hardened photoresist in steps to achieve the arrangement of the silica sol mixed with the activated molecules.

[0038] In some embodiments, the setting range of the silica sol mixed with activated molecules can be the area where the residual photoresist exists on the substrate surface, or it can cover the entire surface of the substrate. The present application does not specifically limit the coating range, as long as it can cover the photoresist to be removed.

[0039] In this embodiment, the specified temperature condition can be achieved by heating the area where the photoresist to be removed is located, or by heating the entire substrate surface, or by heating in advance when the activated molecules are mixed with the silica sol so that the specified temperature condition can be achieved after the silica sol is coated.

[0040] S130: using ultraviolet cleaning technology to remove the silica sol and softened photoresist on the surface of the semiconductor substrate.

[0041] In this embodiment, ultraviolet (UV) cleaning technology can remove organic substances adhering to the surface of the material by utilizing the photosensitive oxidation of organic compounds. The surface of the material after UV cleaning can achieve "atomic cleanliness". Based on the principle of UV degumming, UV cleaning technology can effectively remove a variety of glues including silica sol. Specifically, silica sol is irradiated with ultraviolet light to decompose the chemical bonds in the silica sol, thereby making it lose its viscosity and can be easily removed. Based on a similar principle, in this embodiment, the softened photoresist can also be removed by using UV cleaning technology.

[0042] In this embodiment, the unexpected effect is that the silica sol is used as a carrier of the activated molecules, the cleaning method is relatively mild, and the silica sol can protect the substrate surface, making it difficult to damage the substrate surface during the degumming process, thereby reducing the loss of substrate material caused by the photoresist removal process to a certain extent. In addition, the silica sol and the softened photoresist on the surface of the semiconductor substrate can be removed at the same time through the ultraviolet cleaning process, so that the substrate surface is clean and efficient.

[0043] See also Figure 3 and Figure 4 In some embodiments, the activating molecule comprises: benzotriazole and alcoholamine.

[0044] In some embodiments, using benzotriazole and amine as activation molecules can effectively soften and dissolve the hardened photoresist. The specific activation mechanism is as follows: Benzotriazole is a heterocyclic compound containing three nitrogen atoms, with a chemical formula of C6H5N3 and a molecular structure as shown below: Figure 3 As shown in , for the convenience of explanation, it can be expressed as HN-R. The morphology of the hardened photoresist is similar to that of graphite, which can be expressed as: –C=C–C=C–. Figure 4 As shown, when infrared light (NIR) is used to irradiate to a specified temperature condition, such as 130°C to 200°C, the two can undergo a nucleophilic reaction. Specifically, HN-R attacks the C atom, and the energy provided by the infrared light breaks the double bonds of the hardened photoresist, and the long chain becomes a short chain, thereby achieving the purpose of softening and digestion. In some embodiments, alcoholamine is a class of organic compounds containing hydroxyl (-OH) and amino (-NH2). Alkylamine can promote the dissolution and removal of photoresist through its hydrophilicity and surfactant action, and can effectively enhance the penetration ability and removal effect of the cleaning agent.

[0045] In some embodiments, the step of disposing a silica sol mixed with activated molecules on the photoresist to soften the photoresist under specified temperature conditions includes: uniformly coating the silica sol on the photoresist; adding benzotriazole and amine to the silica sol; and heating the coating area of ​​the silica sol to reach the specified temperature conditions.

[0046] In some embodiments, by uniformly coating the silica sol on the hardened photoresist first, the substrate surface around the photoresist coated with the silica sol can be protected to prevent damage to the substrate surface during subsequent cleaning and removal of the photoresist.

[0047] In some embodiments, Figure 2 As shown in, in the step of heating the coating area of ​​the silica sol to reach the specified temperature condition, infrared light can be used to irradiate the coating area of ​​the silica sol; wherein the duration of the infrared light irradiation falls within the range of 0.5h to 1h.

[0048] In some embodiments, in the silica sol mixed with benzotriazole and olamine, the proportions of each component are: benzotriazole, 0.05% to 0.2%; olamine, 0.02% to 0.05%; the rest is silica sol. Using silica sol as a carrier, mixing benzotriazole and olamine therein, and configuring each component in the above proportion, the softening effect of the photoresist and the subsequent ultraviolet light cleaning is better.

[0049] In some embodiments, residual organic matter is removed from the surface of the semiconductor substrate during the process of removing the silica sol and softened photoresist using ultraviolet cleaning technology; the photoresist removal method further includes: removing the organic matter using a wet cleaning process.

[0050] In some embodiments, the ultraviolet cleaning technology can remove most of the silica sol and softened photoresist, but there may still be some residual organic matter, mainly including some small molecular organic matter. In this case, a wet cleaning process can be used to remove the residual organic matter by washing with some mild cleaning liquid, such as deionized water, so that the semiconductor surface can reach a clean state.

[0051] In order to illustrate the technical effect of the photoresist removal method provided in the embodiment of the present application, the present application also provides a comparison table of the embodiment and the comparative example as shown in Table 1.

[0052] Table 1 It can be seen from the comparison results in Table 1 that, compared with conventional cleaning methods, the photoresist removal method provided in the embodiment of the present application has less substrate material loss and remaining particles. Therefore, the present application can not only effectively reduce the loss of substrate material during the photoresist removal process, but also has a higher cleanliness.

[0053] One embodiment of the present application provides a method for preparing a semiconductor structure, which includes the steps in the method for removing photoresist as described in any of the above embodiments.

[0054] One embodiment of the present application provides a semiconductor structure, which is prepared by the semiconductor structure preparation method described in the above embodiment.

[0055] One embodiment of the present application provides a photoresist cleaning agent, which is applied to the photoresist removal method as described in any of the aforementioned embodiments; the photoresist cleaning agent is composed of the activated molecules and silica sol; wherein the activated molecules include benzotriazole and alcohol amine; the photoresist cleaning agent includes: benzotriazole, 0.05% to 0.2%; alcohol amine, 0.02% to 0.05%; the rest is silica sol.

[0056] An unexpected effect is that the use of silica sol as a carrier of activated molecules makes the cleaning method relatively gentle, and the silica sol can protect the surface of the substrate, making it less likely to cause damage to the substrate surface during the degumming process, thereby reducing the loss of substrate material caused by the removal of the photoresist to a certain extent.

[0057] It should be understood that the specific examples in this article are only intended to help those skilled in the art to better understand the embodiments of the present application, rather than to limit the scope of the present invention.

[0058] It can be understood that in the various implementations of the present application, the size of the serial number of each process does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation methods of the present application.

[0059] It can be understood that the various embodiments described in this application can be implemented individually or in combination, and the embodiments of this application are not limited to this.

[0060] Unless otherwise stated, all technical and scientific terms used in the embodiments of the present application have the same meaning as those generally understood by those skilled in the art of the technical field of the present application. The terms used in the present application are only for the purpose of describing specific embodiments and are not intended to limit the scope of the present application. The term "and / or" used in the present application includes any and all combinations of one or more related listed items. The singular forms of "a kind of", "above" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0061] The above is only a specific implementation of the present application, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for removing a photoresist, characterized in that: include: providing a semiconductor substrate; Hardened photoresist remains on the surface of the semiconductor substrate; Placing silica sol mixed with activation molecules on the photoresist so that the photoresist softens under specified temperature conditions; wherein the silica sol serves as a carrier of the activation molecules; The ultraviolet cleaning technology is used to remove the silica sol and softened photoresist on the surface of the semiconductor substrate.

2. The method for removing the photoresist according to claim 1, characterized in that: The activated molecules include benzotriazole and alcohol amine.

3. The method for removing the photoresist according to claim 2, characterized in that: The step of placing silica sol mixed with activated molecules on the photoresist to soften the photoresist under a specified temperature condition comprises: uniformly coating the silica sol on the photoresist; adding benzotriazole and alcoholamine to the silica sol; The silica sol coating area is heated to reach the specified temperature condition.

4. The method for removing the photoresist according to claim 3, characterized in that: The step of heating the coating area of ​​the silica sol to reach the specified temperature condition comprises: The coating area of ​​the silica sol is irradiated with infrared light; wherein the duration of the infrared light irradiation falls within the range of 0.5h to 1h.

5. The method for removing the photoresist according to claim 2, characterized in that: The specified temperature condition is a temperature range of 130°C to 200°C.

6. The method for removing photoresist according to claim 3, characterized in that: In the silica sol mixed with benzotriazole and olamine, the proportions of each component are: Benzotriazole, 0.05% to 0.2%; Alkylamine, 0.02% to 0.05%; The remaining part is silica sol.

7. The method for removing the photoresist according to any one of claims 1 to 6, characterized in that: Using ultraviolet cleaning technology to remove residual organic matter in the process of removing the silica sol and softened photoresist on the surface of the semiconductor substrate; The photoresist removal method also includes: The organic matter is removed using a wet cleaning process.

8. A method for preparing a semiconductor structure, characterized in that: The method comprises the steps of the photoresist removal method according to any one of claims 1 to 7.

9. A semiconductor structure, characterized in that: The semiconductor structure is prepared by the method for preparing a semiconductor structure described in claim 8.

10. A photoresist cleaning agent, characterized in that: A method for removing photoresist as claimed in any one of claims 1 to 7; the photoresist cleaning agent is composed of the activated molecules and silica sol; wherein the activated molecules include benzotriazole and alcohol amine; the photoresist cleaning agent includes: Benzotriazole, 0.05% to 0.2%; Alkylamine, 0.02% to 0.05%; The remaining part is silica sol.

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