Method for realizing nanopore processing by utilizing two times of photoetching and two times of negative development

Abstract

The invention provides a method for realizing nanopore processing by utilizing two times of photoetching and two times of negative development, and relates to the technical field of photoetching, the method comprises the following steps: forming a to-be-etched film layer, a first photosensitive film layer, a dielectric layer and a second photosensitive film layer which are stacked in sequence on a substrate, the to-be-etched film layer being close to the substrate; performing primary exposure on the second photosensitive film layer by using the nanopore pattern mask, then performing primary negative development, and forming a nanopillar photoetching structure on the second photosensitive film layer; transferring the pattern of the nano column photoetching structure to the dielectric layer to form a column pattern structure; performing secondary exposure on the first photosensitive film layer by using the column pattern structure as a shielding pattern, then performing secondary negative development, and forming a nanopore pattern structure on the first photosensitive film layer; and transferring the pattern of the nano-pore pattern structure to the to-be-etched film layer to obtain the nano-pore structure.

Description

Technical Field

[0001] The present disclosure relates to the field of photolithography technology, and can be applied to technical fields such as storage, sensors, and nano-optics, and in particular to a method for realizing nano-hole processing by utilizing two photolithography steps and two negative development steps. Background Art

[0002] Nanopores are common nanostructures and are widely used in storage, sensors, nano-optics and other fields. The preparation of small-size, high-precision nanopore arrays has become a research hotspot in the field of semiconductor devices. With the continuous development of microelectronics manufacturing technology, there are currently a variety of process methods for the preparation of nanopore structures, such as electron beam lithography, ion beam lithography, nanoimprinting, etc. However, these technologies are difficult to achieve low-cost preparation of large-area, ordered, high-quality nanopore array structures.

[0003] For small-sized and high-density semiconductor nanopore structures, traditional diffraction lithography is often used for exposure and imaging. This method has the advantages of short time consumption and easy implementation, but the two-dimensional structure imaging contrast of diffraction lithography is low, resulting in problems such as insufficient depth of focus, deformed contours, and poor uniformity. In addition, due to the existence of the optical proximity effect, the hole diameters distributed at the edge of the hole array have a large deviation from the designed size, making it difficult to obtain a nanopore array structure with good uniformity and high quality. Summary of the invention

[0004] In view of this, an embodiment of the present disclosure provides a method for realizing nanohole processing by using two photolithography and two negative developments, including: forming a film layer to be etched, a first photosensitive film layer, a dielectric layer and a second photosensitive film layer stacked in sequence on a substrate, wherein the film layer to be etched is close to the substrate; exposing the second photosensitive film layer once using a nanohole pattern mask, and then performing a negative development to form a nanocolumn lithography structure on the second photosensitive film layer; transferring the pattern of the nanocolumn lithography structure to the dielectric layer to form a column pattern structure; exposing the first photosensitive film layer twice using the column pattern structure as a shielding pattern, and then performing a second negative development to form a nanohole pattern structure on the first photosensitive film layer; transferring the pattern of the nanohole pattern structure to the film layer to be etched to obtain a nanohole structure.

[0005] According to an embodiment of the present disclosure, a second photosensitive film layer is exposed once using a nanohole pattern mask, and then a negative development is performed to form a nanocolumn lithography structure on the second photosensitive film layer, including: exposing the second photosensitive film layer once using a nanohole pattern mask so that the second photosensitive film layer area corresponding to the light-transmitting area of ​​the nanohole pattern mask is stimulated to optically react and baked to form a hydrophilic polymer insoluble in a negative development solution; negative development is performed once using a negative development solution on the second photosensitive film layer after the single exposure to dissolve the second photosensitive film layer area corresponding to the non-light-transmitting area of ​​the nanohole pattern mask; and the second photosensitive film layer after the single negative development is cleaned using an organic solution to form a nanocolumn lithography structure.

[0006] According to an embodiment of the present disclosure, a first photosensitive film layer is subjected to secondary exposure using a columnar graphic structure as a shielding pattern, and then secondary negative development is performed to form a nanopore graphic structure on the first photosensitive film layer, including: secondary exposure of the first photosensitive film layer using the columnar graphic structure so that an area of ​​the first photosensitive film layer corresponding to a light-transmitting area of ​​the columnar graphic structure is stimulated to optically react and baked to form a hydrophilic polymer insoluble in a negative development solution; removing the columnar graphic structure; secondary negative development of the first photosensitive film layer after the secondary exposure using a negative development solution to dissolve an area of ​​the first photosensitive film layer corresponding to a non-light-transmitting area of ​​the columnar graphic structure; and cleaning the first photosensitive film layer after the secondary negative development using an organic solution to form a nanopore graphic structure.

[0007] According to an embodiment of the present disclosure, the exposure method includes one of projection lithography, super-resolution lithography, contact lithography, and electron beam lithography, and the exposure wavelength includes i-line, g-line and 193 nm; the negative developing solution includes at least one of n-butyl acetate, ethyl 3-ethoxypropionate, and 2-heptanone; the organic solution includes at least one of methyl isobutyl ketone, 4-methyl-2-pentanol, and isopropanol.

[0008] According to an embodiment of the present disclosure, a film layer to be etched, a first photosensitive film layer, a dielectric layer, and a second photosensitive film layer are stacked in sequence on a substrate, including: forming the film layer to be etched on the substrate by thermal oxidation, electron beam evaporation, magnetron sputtering deposition, chemical vapor deposition or coating; forming the first photosensitive film layer on the film layer to be etched by coating or fumigation; forming the dielectric layer on the first photosensitive film layer by electron beam evaporation, spin coating, spraying, a combination of spin coating and spraying, printing or magnetron sputtering; forming the second photosensitive film layer on the dielectric layer by coating or fumigation.

[0009] According to an embodiment of the present disclosure, the material of the film layer to be etched includes at least one of SiO2, Si3N4, Poly-Si, and TiO2; the material of the dielectric layer includes at least one of Si-BARC, SiO2, Si3N4, Poly-Si, TiN, and TiO2; the material of the first photosensitive film layer and the second photosensitive film layer are the same or different, and the material of the first photosensitive film layer and the second photosensitive film layer includes positive photoresist.

[0010] According to an embodiment of the present disclosure, the thickness of the film layer to be etched is 10 nm to 200 nm, the thickness of the dielectric layer is 10 nm to 50 nm, the thickness of the first photosensitive film layer is 10 nm to 200 nm, and the thickness of the second photosensitive film layer is 10 nm to 100 nm.

[0011] According to the embodiments of the present disclosure, at least one of wet etching, ion beam etching, reactive ion etching, and inductively coupled plasma etching is used to transfer the pattern of the nanocolumn photolithography structure to the dielectric layer; at least one of ion beam etching, reactive ion etching, and inductively coupled plasma etching is used to transfer the pattern of the nanopore graphic structure to the film layer to be etched.

[0012] According to an embodiment of the present disclosure, the solution used for wet etching includes at least one of a dilute hydrofluoric acid solution, a dilute sodium hydroxide solution, and a dilute potassium hydroxide solution; the etching gas used for ion beam etching, reactive ion etching, and inductively coupled plasma etching includes at least one of SF6, CF4, CHF3, and Ar.

[0013] According to an embodiment of the present disclosure, the characteristic size of the nanopore structure is 30 nm to 300 nm, and the period is 60 nm to 500 nm.

[0014] According to the embodiment of the present disclosure, the method for realizing nano-hole processing by using two photolithography and two negative developments has at least the following technical effects:

[0015] This method uses double negative development technology as a process technology to achieve nanopore processing, which can not only improve the imaging contrast of the nanopore pattern, but also avoid the problem of poor pattern contour quality caused by the optical proximity effect of the nanopore array pattern. In addition, the method of achieving higher quality nanopore processing through double exposure and double negative development technology can be applied not only to the manufacture of super-resolution sensors, but also to the field of semiconductor chips at high-tech nodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0017] Figure 1The flowchart of the method for realizing nano-hole processing by using two photolithography and two negative development according to an embodiment of the present disclosure is schematically shown.

[0018] Figure 2 The structural diagrams corresponding to the various stages in the method for realizing nanohole processing by using two photolithography and two negative developments according to an embodiment of the present disclosure are schematically shown.

[0019] Figure 3A The schematic diagram shows a nanorod lithography structure obtained after the first exposure and negative development process according to an embodiment of the present disclosure.

[0020] Figure 3B The schematic diagram shows the structure of the nanopore pattern after the second exposure and negative development process according to an embodiment of the present disclosure.

[0021] Figure 3C The schematic diagram shows a nanopore structure diagram obtained by transferring a pattern of a nanopore graphic structure according to an embodiment of the present disclosure to a membrane layer to be etched. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present disclosure.

[0023] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0024] Similarly, in order to simplify the present disclosure and help understand one or more of the various disclosed aspects, in the above description of the exemplary embodiments of the present disclosure, the various features of the present disclosure are sometimes grouped together into a single embodiment, figure, or description thereof. The description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0025] In addition, 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 the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the feature. In the description of the present disclosure, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0026] The embodiments of the present disclosure aim to provide a method for realizing nano-hole processing by using two photolithography and two negative developments, and realize nano-hole processing by using two photolithography and two negative development techniques.

[0027] Figure 1 The flowchart of the method for realizing nano-hole processing by using two photolithography and two negative development according to an embodiment of the present disclosure is schematically shown.

[0028] like Figure 1 As shown, the nano-hole processing method of this embodiment may include operations S110 to S150.

[0029] In operation S110 , a film layer to be etched, a first photosensitive film layer, a dielectric layer, and a second photosensitive film layer stacked in sequence are formed on a substrate, and the film layer to be etched is close to the substrate.

[0030] In operation S120, the second photosensitive film layer is exposed once using a nanohole pattern mask, and then negatively developed once to form a nanorod lithography structure on the second photosensitive film layer.

[0031] In operation S130 , the pattern of the nano-pillar lithography structure is transferred to the dielectric layer to form a pillar pattern structure.

[0032] In operation S140, the first photosensitive film layer is exposed twice using the pillar pattern structure as a shielding pattern, and then negatively developed twice to form a nanohole pattern structure on the first photosensitive film layer.

[0033] In operation S150 , the pattern of the nanopore pattern structure is transferred to the film layer to be etched to obtain the nanopore structure.

[0034] In the embodiments of the present disclosure, the nanopore pattern mask adopts a nanopore pattern mask consistent with the required lithography pattern period and diameter. The specific pattern period and diameter can be selected according to actual application requirements, and the present disclosure does not limit it. That is, by selecting nanopore pattern masks with different periods and diameters, nanopores with different periods and diameters can be prepared.

[0035] Although the nanopore structure can be obtained by one-time photolithography by directly exposing and developing with a nanopore pattern mask, the imaging contrast of the two-dimensional hole array pattern is low, and there are problems such as difficulty in exposure and poor aperture uniformity. In addition, affected by stray light and light diffraction, the nanopore array pattern is easily distorted, making it difficult to meet the device performance and yield. The nanopore processing method of the embodiment of the present disclosure uses a nanopore pattern mask to expose the second photosensitive film layer for the first time, and then performs the first negative development; the column pattern structure is used as a shielding pattern to expose the first photosensitive film layer for the second time, and then performs the second negative development. Compared with the nanopore pattern obtained by a single exposure, the nano-column structure in this method is less subject to light scattering and reflection, and the light can penetrate the photoresist more directly, and the exposure is more uniform; at the same time, the photoresist of the nano-column structure is easier to remove evenly during development, thereby improving the pattern accuracy; in addition, the nano-column structure is less affected by the optical proximity effect, the pattern is clearer and the pattern distortion problem is reduced. Therefore, the nanopore processing method of the embodiment of the present disclosure can not only improve the imaging contrast of the nanopore pattern, but also avoid the problems such as poor pattern contour quality caused by the optical proximity effect of the nanopore array pattern.

[0036] Based on the above embodiment, the second photosensitive film layer is exposed once using a nanohole pattern mask in operation S120, and then negative development is performed to form a nanocolumn lithography structure on the second photosensitive film layer, including:

[0037] The second photosensitive film layer is exposed once using a nanopore pattern mask, so that the second photosensitive film layer area corresponding to the light-transmitting area of ​​the nanopore pattern mask is stimulated to react optically and baked to form a hydrophilic polymer insoluble in a negative developing solution.

[0038] The second photosensitive film layer after the first exposure is negatively developed by using a negative developing solution to dissolve the second photosensitive film layer area corresponding to the non-light-transmitting area of ​​the nanohole pattern mask.

[0039] The second photosensitive film layer after the first negative development is cleaned by using an organic solution to form a nano-column lithography structure.

[0040] Based on the above embodiment, the first photosensitive film layer is subjected to secondary exposure using the pillar pattern structure in operation S140, and then secondary negative development is performed to form a nanopore pattern structure on the first photosensitive film layer, including:

[0041] The first photosensitive film layer is exposed twice using the column pattern structure as a shielding pattern, so that the first photosensitive film layer area corresponding to the light-transmitting area of ​​the column pattern structure is stimulated to react optically and baked to form a hydrophilic polymer insoluble in a negative developing solution.

[0042] The columnar graphic structure, ie, the dielectric layer, is removed.

[0043] The first photosensitive film layer after the secondary exposure is subjected to secondary negative development using a negative developing solution to dissolve the first photosensitive film layer corresponding to the non-light-transmitting area of ​​the column pattern structure.

[0044] The first photosensitive film layer after the secondary negative development is cleaned with an organic solution to form a nanopore graphic structure.

[0045] According to the embodiments of the present disclosure, the light-transmitting area on the nanopore pattern mask causes the corresponding area of ​​the second photosensitive film layer to be stimulated to undergo a photochemical reaction, producing acid. After baking, the polarity of the polymer changes, and the polymer becomes hydrophilic and no longer dissolves in the negative developing solution. However, in the non-light-transmitting area on the nanopore pattern mask, the material properties of the second photosensitive film layer in the corresponding area do not change, and the polymer still dissolves in the negative developing solution. Therefore, the photoresist in the unexposed area of ​​the second photosensitive film layer is dissolved, and the photosensitive part is retained. In other words, the hole pattern on the nanopore pattern mask forms a nanocolumn lithography structure in the corresponding area on the second photosensitive film layer.

[0046] Similarly, the light-transmitting area around the column graphic structure causes the corresponding area of ​​the first photosensitive film layer to be stimulated to react with light, producing acid. After baking, the polarity of the polymer changes, and the polymer becomes hydrophilic and no longer dissolves in the negative developing solution. However, in the non-light-transmitting area below the column graphic structure, the material properties of the first photosensitive film layer in the corresponding area do not change and still dissolve in the negative developing solution. Therefore, the photoresist in the unexposed area on the first photosensitive film layer is dissolved, and the photosensitive part is retained. In other words, the column graphic structure can form a nanopore graphic structure in the corresponding area on the first photosensitive film layer.

[0047] Since a dielectric layer is formed between the first photosensitive film layer and the second photosensitive film layer, exposing and negatively developing the second photosensitive film layer using a nanohole pattern mask will not affect the first photosensitive film layer, thereby making the material selection, exposure mode and development method of the two photoresists unrestricted, that is, the two exposure processes and development processes can be the same or different.

[0048] Based on the above embodiment, the double exposure method may include one of projection lithography, super-resolution lithography, contact lithography, and electron beam lithography, and the exposure wavelength may include i-line, g-line, and 193 nm. Among them, i-line refers to ultraviolet light with a wavelength of 365 nanometers, and g-line refers to ultraviolet light with a wavelength of 436 nanometers.

[0049] The negative developing solution of the double development may include at least one of n-butyl acetate, ethyl 3-ethoxypropionate, and 2-heptanone;

[0050] The organic solution may include at least one of methyl isobutyl ketone, 4-methyl-2-pentanol, and isopropanol.

[0051] On the basis of the above embodiment, the step of forming a film layer to be etched, a first photosensitive film layer, a dielectric layer, and a second photosensitive film layer stacked in sequence on the substrate in operation S110 may include:

[0052] The film layer to be etched is formed on the substrate by thermal oxidation, electron beam evaporation, magnetron sputtering deposition, chemical vapor deposition or coating.

[0053] A first photosensitive film layer is formed on the film layer to be etched by coating or fumigation.

[0054] The dielectric layer is formed on the first photosensitive film layer by electron beam evaporation, spin coating, spray coating, a combination of spin coating and spray coating, printing or magnetron sputtering.

[0055] A second photosensitive film layer is formed on the dielectric layer by coating or fumigation.

[0056] Further, as some feasible implementations, the material of the film layer to be etched may include at least one of SiO2, Si3N4, Poly-Si, and TiO2. The material of the dielectric layer may include at least one of Si-BARC, SiO2, Si3N4, Poly-Si, TiN, and TiO2. The materials of the first photosensitive film layer and the second photosensitive film layer may be the same or different, and the materials of the first photosensitive film layer and the second photosensitive film layer may include positive photoresist.

[0057] The thickness of the film layer to be etched may be 10 nm to 200 nm, the thickness of the dielectric layer may be 10 nm to 50 nm, the thickness of the first photosensitive film layer may be 10 nm to 200 nm, and the thickness of the second photosensitive film layer may be 10 nm to 100 nm.

[0058] Based on the above embodiments, at least one of wet etching, ion beam etching (IBE), reactive ion etching (RIE), and inductively coupled plasma etching (ICP) can be used to transfer the pattern of the nanorod lithography structure to the dielectric layer.

[0059] At least one of ion beam etching, reactive ion etching and inductively coupled plasma etching can be used to transfer the pattern of the nanopore pattern structure to the film layer to be etched.

[0060] Further, as some feasible implementation methods, the solution used for wet etching includes at least one of a dilute hydrofluoric acid solution, a dilute sodium hydroxide solution, and a dilute potassium hydroxide solution.

[0061] The etching gas used in ion beam etching, reactive ion etching and inductively coupled plasma etching includes at least one of SF6, CF4, CHF3 and Ar.

[0062] In order to more clearly illustrate the effectiveness of the nanopore processing method provided by the embodiment of the present disclosure, Figure 2 and Figure 3A-3C , is described based on some specific embodiments. Figure 2 The structure diagram corresponding to each stage in the nanohole processing method according to the embodiment of the present disclosure is schematically shown. Figure 3A The schematic diagram shows the nanorod lithography structure obtained after the first exposure and negative development process according to the embodiment of the present disclosure. Figure 3B The schematic diagram shows the nanopore pattern structure after the second exposure and negative development process according to the embodiment of the present disclosure, Figure 3C The schematic diagram shows a nanopore structure diagram obtained by transferring a pattern of a nanopore graphic structure according to an embodiment of the present disclosure to a membrane layer to be etched.

[0063] Embodiment 1:

[0064] The implementation steps of the method for fabricating nanoholes using two-time photolithography and two-time negative development technology provided in this embodiment can be as follows:

[0065] Step 1-1: depositing an etched layer 2 on a substrate 1 by magnetron sputtering, wherein the etched layer 2 is Poly-Si with a thickness of 70 nm.

[0066] Step 1-2: Prepare the first photosensitive film layer 3 by spin coating. The material of the first photosensitive film layer 3 is I-Line photoresist HTI751. The rotation speed is 4000 rpm. The spin coating time is 40 s. Bake on a hot plate at 100 °C for 3 minutes to form a photoresist layer with a thickness of 30 nm.

[0067] Step 1-3: A SiO2 dielectric layer 4 is prepared by vacuum evaporation process. The thickness of the SiO2 dielectric layer 4 is 20 nm and the deposition rate is 2.5 A / s.

[0068] Step 1-4: Prepare the second photosensitive film layer 5 by spin coating. The material of the second photosensitive film layer 5 is I-Line photoresist HTI751. The rotation speed is 4000 rpm. The spin coating time is 40 s. The film is baked on a hot plate at 100 °C for 3 minutes. The thickness of the photoresist layer is 30 nm. The structure prepared is as follows: Figure 2 As shown in a.

[0069] Step 1-5: Perform a super-resolution exposure on the second photosensitive film layer 5, the exposure dose is 300 mJ, the hole size of the hole mask is 150 nm, and the period is 300 nm. Figure 2 As shown in b.

[0070] Step 1-6: Soak the exposed substrate in n-butyl acetate for 1 min for negative development, then rinse the substrate surface with isopropanol solution and blow dry with N2 to obtain a columnar pattern structure with a half-period of 150 nm on the second photosensitive film layer 5. The prepared structure is as follows Figure 2 In c and Figure 3A shown.

[0071] Step 1-7: The column pattern structure is further transferred to the SiO2 dielectric layer 4 by solution wet etching. Prepare a 1:100 HF:DI aqueous solution, soak the above sample for 10 s to remove the SiO2 dielectric layer 4, then rinse it and blow dry it with N2. The prepared structure is as follows Figure 2 As shown in middle d.

[0072] Step 1-8: The first photosensitive film layer 3 is subjected to secondary exposure, and the exposure dose is 300 mJ. No mask is required, and the pattern structure of the dielectric layer is transferred to the first photosensitive film layer 3 by photolithography. The structure prepared is as follows Figure 2 As shown in figure e.

[0073] Step 1-9: Prepare 1:100 HF:DI aqueous solution, soak the above sample for 10 s to remove SiO2 dielectric layer 4, then rinse it and blow dry it with N2.

[0074] Step 1-10: Soak the substrate after secondary exposure in n-butyl acetate for 1 min for secondary negative development, then rinse it with isopropanol and blow dry it with N2 to obtain a nanopore structure with a half-period of 150 nm in the first photosensitive film layer 3. The prepared structure is as follows Figure 2 Medium f and Figure 3B shown.

[0075] Step 1-11: Use ICP to further transfer the hole pattern structure to the Poly-Si layer. Use 100 W ICP RF power and 20 W lower electrode power, 20 sccm CHF3 and 5 sccm SF6 mixed gas for etching. The prepared structure is as follows Figure 2 As shown in g and Figure 3C As shown, a nanopore structure with a size of 150 nm and a period of 300 nm was finally prepared.

[0076] Embodiment 2:

[0077] The implementation steps of the method for fabricating nanoholes using two-time photolithography and two-time negative development technology provided in this embodiment can be as follows:

[0078] Step 2-1: Deposit an etched layer 2 on a substrate 1 by magnetron sputtering. The etched layer 2 is SiO2 with a thickness of 100 nm.

[0079] Step 2-2: Prepare the first photosensitive film layer 3 by spin coating. The material of the first photosensitive film layer 3 is I-Line photoresist HTI751. The rotation speed is 2000 rpm. The spin coating time is 40 s. Bake on a hot plate at 100 °C for 5 minutes to form a photoresist layer with a thickness of 20 nm.

[0080] Step 2-3: A SiN dielectric layer 4 is prepared by vacuum evaporation. The SiN dielectric layer 4 has a thickness of 10 nm and a deposition rate of 2.0 A / s.

[0081] Step 2-4: Prepare the second photosensitive film layer 5 by spin coating. The material of the second photosensitive film layer 5 is 193nm photoresist ARF-88. The rotation speed is 3000 rpm. The spin coating time is 40 s. The film is baked on a hot plate at 100°C for 3 minutes. The thickness of the photoresist layer is 60 nm. The structure prepared is as follows: Figure 2 As shown in a.

[0082] Step 2-5: Perform a projection exposure on the second photosensitive film layer 5, the exposure dose is 50 mJ, the hole size of the hole mask is 60 nm, and the period is 120 nm. The structure of a single exposure is as follows: Figure 2 As shown in b.

[0083] Step 2-6: Soak the substrate after the first exposure in n-butyl acetate for 1 min for a negative development, then rinse it with isopropanol and blow it dry with N2 to obtain a column structure with a half-period of 60 nm in the second photosensitive film layer 5. The prepared structure is as follows Figure 2 In c and Figure 3A shown.

[0084] Step 2-7: The pillar pattern structure is further transferred to the SiN dielectric layer 4 by RIE etching, and the etching is performed using 20 W RF power and 20 sccm CHF3 gas. The prepared structure is as follows Figure 2 As shown in middle d.

[0085] Step 2-8: The first photosensitive film layer 3 is subjected to secondary exposure, and the exposure dose is 200 mJ. No mask is required, and the pattern structure of the dielectric layer is transferred to the first photosensitive film layer 3 by photolithography. The structure prepared is as follows Figure 2 As shown in figure e.

[0086] Step 2-9: Remove the SiN dielectric layer 4 on the surface of the first photosensitive film layer 3 by RIE etching, using 20 W of RF power and 20 sccm of CHF3 gas for etching.

[0087] Step 2-10: Soak the substrate after the secondary exposure in n-butyl acetate for 1 minute for secondary negative development, then rinse it with isopropanol and blow it dry with N2 to obtain a nanopore structure with a half-period of 60 nm in the first photosensitive film layer 3. The prepared structure is as follows Figure 2 Medium f and Figure 3B shown.

[0088] Step 2-11: Use ICP to further transfer the hole pattern structure to the SiO2 layer. Use 100 W ICP RF power and 20 W lower electrode power, 20 sccm CHF3 gas for etching. The prepared structure is as follows Figure 2 As shown in g and Figure 3C As shown, a nanopore structure with a size of 60 nm and a period of 120 nm was finally prepared.

[0089] Based on the processing method provided in the embodiment of the present disclosure, the characteristic size of the prepared nanopore structure can be 30 nm to 300 nm, and the period can be 60 nm to 500 nm.

[0090] It should be noted that the specific parameters, material types and processing methods involved in the above examples are all for the purpose of more clearly illustrating the processing methods provided by the embodiments of the present disclosure, and are not intended to limit the present disclosure.

[0091] The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present disclosure in detail. It should be understood that the above are only preferred embodiments of the present disclosure and the technical principles used. Those skilled in the art will understand that the present disclosure is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present disclosure. Therefore, although the present disclosure is described in more detail through the above embodiments, the present disclosure is not limited to the above embodiments, and may also include more other equivalent embodiments without departing from the concept of the present disclosure, all of which belong to the protection scope of the present disclosure.

Claims

1. A method for realizing nanopore processing by using two photolithography and two negative developments, characterized in that: include: Forming a film layer to be etched, a first photosensitive film layer, a dielectric layer, and a second photosensitive film layer stacked in sequence on a substrate, wherein the film layer to be etched is close to the substrate; The second photosensitive film layer is exposed once using a nano-hole pattern mask, and then negatively developed once to form a nano-column lithography structure on the second photosensitive film layer; Transferring the pattern of the nano-pillar photolithography structure to the dielectric layer to form a pillar pattern structure; Using the column pattern structure as a shielding pattern, the first photosensitive film layer is subjected to secondary exposure, and then secondary negative development is performed to form a nanopore pattern structure on the first photosensitive film layer; The pattern of the nanopore pattern structure is transferred to the film layer to be etched to obtain a nanopore structure.

2. The method according to claim 1, characterized in that: The method of exposing the second photosensitive film layer once by using a nano-hole pattern mask, and then performing a negative development to form a nano-column lithography structure on the second photosensitive film layer, comprises: The second photosensitive film layer is exposed once by using the nanopore pattern mask, so that the second photosensitive film layer area corresponding to the light-transmitting area of ​​the nanopore pattern mask is stimulated to react optically and baked to form a hydrophilic polymer insoluble in a negative developing solution; Performing a negative development on the second photosensitive film layer after the first exposure using a negative developing solution to dissolve the second photosensitive film layer area corresponding to the non-light-transmitting area of ​​the nanohole pattern mask; The second photosensitive film layer after the first negative development is cleaned with an organic solution to form the nano-column lithography structure.

3. The method according to claim 1, characterized in that: The method of performing secondary exposure on the first photosensitive film layer by using the column pattern structure as a shielding pattern, and then performing secondary negative development to form a nanopore pattern structure on the first photosensitive film layer, comprises: The first photosensitive film layer is subjected to secondary exposure using the column pattern structure as a shielding pattern, so that the first photosensitive film layer area corresponding to the light-transmitting area of ​​the column pattern structure is stimulated to react optically and baked to form a hydrophilic polymer insoluble in a negative developing solution; removing the column graphic structure; Performing secondary negative development on the second-exposed first photosensitive film layer using a negative developing solution to dissolve the first photosensitive film layer region corresponding to the non-light-transmitting region of the column pattern structure; The first photosensitive film layer after the secondary negative development is cleaned with an organic solution to form the nanopore graphic structure.

4. The method according to claim 2 or 3, characterized in that: The exposure method includes one of projection lithography, super-resolution lithography, contact lithography, and electron beam lithography, and the exposure wavelength includes i-line, g-line and 193 nm; The negative developing solution comprises at least one of n-butyl acetate, ethyl 3-ethoxypropionate, and 2-heptanone; The organic solution includes at least one of methyl isobutyl ketone, 4-methyl-2-pentanol, and isopropanol.

5. The method according to claim 1, characterized in that The method of forming a film layer to be etched, a first photosensitive film layer, a dielectric layer and a second photosensitive film layer stacked in sequence on a substrate comprises: Forming the film layer to be etched on the substrate by thermal oxidation, electron beam evaporation, magnetron sputtering deposition, chemical vapor deposition or coating; Forming the first photosensitive film layer on the film layer to be etched by coating or fumigation; Forming the dielectric layer on the first photosensitive film layer by electron beam evaporation, spin coating, spray coating, a combination of spin coating and spray coating, printing or magnetron sputtering; The second photosensitive film layer is formed on the dielectric layer by coating or fumigation.

6. The method according to claim 1 or 5, characterized in that: The material of the film layer to be etched includes at least one of SiO2, Si3N4, Poly-Si, and TiO2; The material of the dielectric layer includes at least one of Si-BARC, SiO2, Si3N4, Poly-Si, TiN, and TiO2; The materials of the first photosensitive film layer and the second photosensitive film layer are the same or different, and the materials of the first photosensitive film layer and the second photosensitive film layer include positive photoresist.

7. The method according to claim 1 or 5, characterized in that: The thickness of the film layer to be etched is 10 nm to 200 nm, the thickness of the dielectric layer is 10 nm to 50 nm, the thickness of the first photosensitive film layer is 10 nm to 200 nm, and the thickness of the second photosensitive film layer is 10 nm to 100 nm.

8. The method according to claim 1, characterized in that Using at least one of wet etching, ion beam etching, reactive ion etching, and inductively coupled plasma etching to transfer the pattern of the nanorod photolithography structure to the dielectric layer; At least one of ion beam etching, reactive ion etching and inductively coupled plasma etching is used to transfer the pattern of the nanopore pattern structure to the film layer to be etched.

9. The method according to claim 8, characterized in that The solution used for the wet etching includes at least one of a dilute hydrofluoric acid solution, a dilute sodium hydroxide solution, and a dilute potassium hydroxide solution; The etching gas used in the ion beam etching, reactive ion etching and inductively coupled plasma etching includes at least one of SF6, CF4, CHF3 and Ar.

10. The method according to claim 1, characterized in that The characteristic size of the nanopore structure is 30 nm to 300 nm, and the period is 60 nm to 500 nm.

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