Imaging structure protection method and structure of plasma resonance cavity lens lithography

Abstract

The present disclosure provides a method and structure for protecting an imaging structure of a plasma resonant cavity lens lithography, the method comprising: S1, depositing a reflective metal film layer on a substrate surface; S2, depositing a protective film layer on the reflective metal film layer, the protective film layer being used to protect the reflective metal film layer; S3, preparing a photosensitive film layer on the protective film layer; S4, depositing a transparent protective film layer on the photosensitive film layer, the transparent protective film layer being used to protect the photosensitive film layer; S5, depositing a transmissive metal film layer on the transparent protective film layer to obtain an imaging structure of a plasma resonant cavity lens lithography. The present disclosure avoids damage and destruction to the photosensitive film layer caused by a metal-removing corrosive solution and a developer to the reflective metal film layer by arranging a protective film layer and a transparent protective film layer on the reflective metal film layer and the transmissive metal film layer, respectively, and is conducive to improving the pattern quality of the plasma resonant cavity imaging lithography.

Description

Technical Field

[0001] The present disclosure relates to the technical field of super-resolution imaging, and in particular to a method and structure for protecting an imaging structure of a plasma resonance cavity lens lithography. Background Art

[0002] For traditional projection imaging optical lithography systems, the evanescent waves carrying the sub-wavelength information of the mask pattern cannot participate in imaging, resulting in a resolution limit of 1 / 4 wavelength line width. The main principle of surface plasmons (SP) super-resolution imaging lithography is to use nano-metal imaging film structures such as super lenses to excite SP modes in a wide spatial spectrum range and enhance the intensity of evanescent waves carrying high-frequency spatial information, and use the negative refraction imaging effect to achieve the mask pattern transfer to the photoresist space and super-resolution imaging lithography.

[0003] The superlens structure was first used in the research of super-resolution imaging technology. It mainly uses the metal film to excite the SP light field on both sides when the mask pattern is illuminated by ultraviolet light, and realizes the super-resolution imaging lithography of the mask pattern with a magnification of 1:1 in the photoresist space on the other side of the metal film. In order to improve the SP excitation efficiency and compress the SP wavelength, the superlens structure is combined with the reflective lens structure to integrate the advantages of the two to form a SP resonant cavity imaging structure composed of metal-medium-metal. From the simulation analysis, the SP resonant cavity imaging structure has higher imaging resolution and pattern depth than the superlens and reflective imaging lithography. However, in the actual process experiment, the photoresist in the SP resonant cavity is sandwiched by two layers of metal, resulting in the inability to directly carry out the development process without removing the surface metal after exposure, and thus the pattern structure cannot be obtained.

[0004] The common method of metal removal is to use a certain concentration of corrosive solution to corrode the metal to achieve the purpose of removal. However, in the process of removing the surface metal with the corrosive solution, the corrosive solution often causes certain damage and destruction to the photosensitive film layer. In the development process, the developer will also cause certain damage to the reflective metal film layer, thus affecting the quality of high-resolution graphics.

[0005] Therefore, developing the protection technology of photoresist and underlying metal in the process of removing the surface metal layer will be the key technology in SP resonant cavity imaging lithography. Summary of the invention

[0006] 1. Technical issues to be resolved

[0007] In response to the above problems, the present disclosure provides a method and structure for protecting the imaging structure of plasma resonance cavity lens lithography, which are used to solve technical problems such as the existing metal removal corrosion solution is easy to damage the photosensitive film layer and the developer is easy to damage the reflective metal film layer.

[0008] (II) Technical solution

[0009] On the one hand, the present disclosure provides a method for protecting an imaging structure of a plasma resonant cavity lens lithography, comprising: S1, depositing a reflective metal film layer on a substrate surface; S2, depositing a protective film layer on the reflective metal film layer, the protective film layer being used to protect the reflective metal film layer; S3, preparing a photosensitive film layer on the protective film layer; S4, depositing a transparent protective film layer on the photosensitive film layer, the transparent protective film layer being used to protect the photosensitive film layer; S5, depositing a transmissive metal film layer on the transparent protective film layer to obtain an imaging structure of the plasma resonant cavity lens lithography.

[0010] Furthermore, the substrate in S1 includes one of a silicon substrate, a quartz substrate, a magnesium fluoride substrate and a flexible substrate.

[0011] Furthermore, the method for depositing the reflective metal film layer in S1 includes one of magnetron sputtering deposition, thermal evaporation deposition or chemical vapor deposition; the reflective metal film layer includes one of Ag, Al, and Au.

[0012] Furthermore, the method for depositing the protective film layer in S2 includes one of magnetron sputtering deposition, atomic layer deposition, chemical vapor deposition and vacuum evaporation deposition; the protective film layer includes one of SiO2, Al2O3, and MgF2.

[0013] Furthermore, the thickness of the protective film layer is 2-10 nm.

[0014] Furthermore, the photosensitive film layer in S3 includes one of ultraviolet phenolic resin system photoresist, polystyrene system photoresist, and molecular glass system photoresist.

[0015] Furthermore, the method for depositing the transparent protective film layer in S4 includes one of magnetron sputtering deposition, atomic layer deposition, chemical vapor deposition and vacuum evaporation deposition; the transparent protective film layer includes one of SiO2 and Si3N4; the thickness of the transparent protective film layer is 2 to 10 nm.

[0016] Furthermore, the method of depositing the transmissive metal film layer in S5 includes one of magnetron sputtering deposition, atomic layer deposition, chemical vapor deposition and vacuum evaporation deposition; the transmissive metal film layer includes one of Ag, Al and Au.

[0017] On the other hand, the present disclosure provides an imaging structure of plasma resonance cavity lens lithography, and the imaging structure is prepared by using the aforementioned imaging structure protection method of plasma resonance cavity lens lithography.

[0018] Another aspect of the present disclosure provides an application of the imaging structure of the aforementioned plasma resonance cavity lens lithography in surface plasmon super-resolution imaging lithography.

[0019] (III) Beneficial effects

[0020] The imaging structure protection method of the plasma resonance cavity lens lithography disclosed in the present invention can prepare a sub-ten nanometer thickness imaging structure protection layer by using only conventional coating processes, thereby preventing the plasma resonance cavity imaging structure from causing damage and destruction to the photosensitive film layer and the reflective metal film layer during the wet removal of the surface metal. Specifically, by setting a protective film layer on the reflective metal film layer and setting a transparent protective film layer on the photosensitive film layer, the transparent protective film layer is used to protect the photosensitive film layer from being damaged by the corrosive solution when the transmissive metal film layer is removed; the protective film layer is used to protect the reflective metal film layer from being damaged by the developer when the photosensitive film layer is developed, and neither affects the exposure process. The dual combination of the protective film layer and the transparent protective film layer synergistically protects the integrity of the imaging structure and improves the image quality of the plasma resonance cavity imaging lithography. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A flowchart schematically shows a method for protecting an imaging structure of a plasma resonance cavity lens lithography according to an embodiment of the present disclosure;

[0022] Figure 2 The schematic diagram shows the imaging structure and mask structure of the plasma resonance cavity lens lithography obtained by the preparation method according to the embodiment of the present disclosure;

[0023] Figure 3 A schematic diagram of a structure of wet etching of an imaging structure of a plasma resonance cavity lens lithography obtained by the preparation method according to an embodiment of the present disclosure is shown;

[0024] Figure 4 A schematic diagram of the structure after the transmissive metal film layer in the imaging structure of the plasma resonance cavity lens lithography obtained by the preparation method according to the embodiment of the present disclosure is corroded;

[0025] Figure 5 A schematic diagram of the structure after the transparent protective film layer in the imaging structure of the plasma resonance cavity lens photolithography obtained by the preparation method according to the embodiment of the present disclosure is etched;

[0026] Figure 6 A schematic diagram of a graphic structure obtained after developing the imaging structure of the plasma resonance cavity lens photolithography obtained by the preparation method according to an embodiment of the present disclosure is schematically shown;

[0027] Figure 7 Schematically showing a light field simulation diagram (a) of a 32nm resolution pattern obtained by the imaging structure of the plasma resonance cavity lens lithography obtained by the preparation method according to an embodiment of the present disclosure and a light field distribution curve diagram at the middle depth of the photosensitive layer (b);

[0028] Figure 8 A schematic diagram showing a graphic structure obtained after developing an imaging structure of a plasma resonance cavity lens photolithography obtained by a preparation method according to an embodiment of the present disclosure;

[0029] Fig. 9 The diagram schematically shows the imaging structure of the plasma resonance cavity lens lithography without a protective film layer and a transparent protective film layer according to the embodiment of the present disclosure after the transmissive metal film layer is removed;

[0030] Fig.10 The diagram schematically shows the imaging structure of the plasma resonance cavity lens lithography with a protective film layer and without a transparent protective film layer after the transmissive metal film layer is removed according to the embodiment of the present disclosure;

[0031] Description of Figure Numbers:

[0032] 1, substrate; 2, reflective metal film layer; 3, protective film layer; 4, photosensitive film layer; 5, transparent protective film layer; 6, transmissive metal film layer; 7, mask light-blocking layer; 8, mask pattern structure; 9, mask substrate; 10, illumination incident light; 11, wet etching solution. DETAILED DESCRIPTION

[0033] In order to make the objectives, 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.

[0034] 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.

[0035] It should be noted that if directional indication is involved in the embodiments of the present disclosure, the directional indication is only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0036] The embodiment of the present disclosure provides a method for protecting the imaging structure of a plasma resonance cavity lens lithography, see Figure 1 , including: S1, depositing a reflective metal film layer 2 on the surface of a substrate 1; S2, depositing a protective film layer 3 on the reflective metal film layer 2, the protective film layer 3 is used to protect the reflective metal film layer 2; S3, preparing a photosensitive film layer 4 on the protective film layer 3; S4, depositing a transparent protective film layer 5 on the photosensitive film layer 4, the transparent protective film layer 5 is used to protect the photosensitive film layer 4; S5, depositing a transmissive metal film layer 6 on the transparent protective film layer 5, to obtain an imaging structure of a plasma resonance cavity lens lithography.

[0037] The preparation method disclosed in the present invention is applied to a plasma resonant cavity lens structure, specifically a SP resonant cavity imaging structure composed of metal-medium-metal. Figure 2 The schematic diagram of the imaging structure and mask of the plasma resonant cavity lens lithography obtained by the preparation method of the present disclosure is shown. In the process of preparing the SP resonant cavity imaging structure, the present disclosure sets a protective film layer 3 on the reflective metal film layer 2, and sets a transparent protective film layer 5 on the photosensitive film layer 4. When the transmissive metal film layer 6 is removed, the transparent protective film layer 5 is used to protect the photosensitive film layer 4 from being damaged by the corrosive solution; when the photosensitive film layer 4 is developed, the protective film layer 3 is used to protect the reflective metal film layer 2 from being damaged by the developer, and the protective film layer 3 and the transparent protective film layer 5 do not affect the exposure process. The dual combination of the protective film layer 3 and the transparent protective film layer 5 synergistically protects the integrity of the SP resonant cavity imaging structure and improves the pattern quality of the plasma resonant cavity imaging lithography.

[0038] On the basis of the above embodiment, the substrate 1 in S1 includes one of a silicon substrate, a quartz substrate, a magnesium fluoride substrate and a flexible substrate. The method of depositing the reflective metal film layer 2 in S1 includes one of magnetron sputtering deposition, thermal evaporation deposition or chemical vapor deposition; the reflective metal film layer 2 includes one of Ag, Al and Au.

[0039] Step S1: First, a reflective metal film layer 2 is prepared on a substrate. The material of the reflective metal film layer 2 is not limited to Ag, Al, Au, and may also be other materials that can excite surface plasma. This step adopts a conventional metal deposition process, and the thickness of the prepared reflective metal film layer 2 is 10 to 200 nanometers. There are no special requirements for the material of the substrate and the deposition process.

[0040] Based on the above embodiment, the method of depositing the protective film layer 3 in S2 includes one of magnetron sputtering deposition, atomic layer deposition, chemical vapor deposition and vacuum evaporation deposition; the protective film layer 3 includes one of SiO2, Al2O3, and MgF2. The thickness of the protective film layer 3 is 2 to 10 nm.

[0041] A protective film layer 3 is deposited on the reflective metal film layer 2. The protective film layer 3 is made of a material resistant to corrosion by a developer. SiO2, Al2O3, MgF2 or other dielectric materials can be used for the protective film layer 3. SiO2, Al2O3 and MgF2 have the characteristics of high chemical stability and have a relatively stable effect when used to protect the reflective metal film layer. The thickness of the protective film layer 3 is within this range to ensure that the processed protective layer can be continuously formed.

[0042] On the basis of the above embodiment, the photosensitive film layer 4 in S3 includes one of ultraviolet phenolic resin system photoresist, polystyrene system photoresist and molecular glass system photoresist.

[0043] Specifically, the photosensitive film layer 4 may be an AR series, an AZ series or other series of photosensitive materials that are sensitive to light at a wavelength of 365 nm.

[0044] Based on the above embodiment, the method for depositing the transparent protective film layer 5 in S4 includes one of magnetron sputtering deposition, atomic layer deposition, chemical vapor deposition and vacuum evaporation deposition; the transparent protective film layer 5 includes one of SiO2 and Si3N4; the thickness of the transparent protective film layer 5 is 2 to 10 nm.

[0045] The transparent protective film layer 5 does not react with the corrosive solution of the transmissive metal film layer and is resistant to the corrosion of the corrosive solution. The transparent protective film layer 5 can be SiO2, Si3N4 or other transparent dielectric materials. In order not to affect the loss of illumination light during the exposure process, the transparent protective film layer 5 is preferably a transparent dielectric material. The protective film layer 3 also needs to have a transmittance of more than 60% for ultraviolet light. The thickness of the transparent protective film layer 5 can be the same as or different from that of the protective film layer 3. The thickness of the two is determined according to actual needs.

[0046] The present invention selects a transparent protective film layer resistant to metal corrosion liquid to protect the photosensitive film layer and the underlying reflective metal film layer, thereby overcoming the damage and destruction problem of the photosensitive film layer and the underlying reflective metal film layer caused by the corrosion process of the surface transmissive metal film layer in the current SP resonant cavity lithography, which is beneficial to improving the lithography quality of super-resolution graphics.

[0047] Based on the above embodiment, the method of depositing the transmissive metal film layer 6 in S5 includes one of magnetron sputtering deposition, atomic layer deposition, chemical vapor deposition and vacuum evaporation deposition; the transmissive metal film layer 6 includes one of Ag, Al and Au.

[0048] The material used to prepare the surface transmissive metal film layer 6 can be Ag, Al, Au, or other materials with negative dielectric constants. The deposition method can be magnetron sputtering deposition, atomic layer deposition, chemical vapor deposition, or vacuum evaporation deposition.

[0049] The present disclosure also provides an imaging structure for plasma resonance cavity lens lithography, and the imaging structure is prepared by using the aforementioned imaging structure protection method for plasma resonance cavity lens lithography.

[0050] Through the preparation method disclosed in the present invention, it is only necessary to use conventional coating and etching processes to prepare an imaging structure protection layer with a thickness of sub-ten nanometers, thereby realizing super-resolution lithography of 32nm and below graphics, and solving the problem that the photosensitive film layer and the underlying reflective metal film layer are damaged and destroyed during the wet removal of the surface transmissive metal film layer of the SP resonant cavity imaging structure, thereby affecting the graphics quality.

[0051] The present disclosure also provides an application of the imaging structure based on the aforementioned plasma resonance cavity lens lithography in surface plasmon super-resolution imaging lithography.

[0052] The present invention protects the photosensitive film layer and the underlying reflective metal film layer by selecting a transparent film layer resistant to metal corrosion liquid, thereby ensuring the integrity of the imaging structure and providing an important basis for subsequent graphic transfer, thereby facilitating improving the graphic quality of plasma resonance cavity imaging lithography.

[0053] The present disclosure is further described below through specific implementations. In the following embodiments, the imaging structure protection method and structure of the plasma resonance cavity lens lithography are specifically described. However, the following embodiments are only used to illustrate the present disclosure, and the scope of the present disclosure is not limited thereto.

[0054] The imaging structure protection method and exposure and development method of the plasma resonance cavity lens lithography in the following embodiments include the following steps: Figure 1 , Figure 2 As shown:

[0055] Step (1): Select a flat substrate 1.

[0056] Step (2): preparing a bottom reflective metal film layer 2 on the surface of the substrate 1, wherein the thickness of the bottom reflective metal film layer 2 is d1 = 10 to 200 nm; equivalent to the above-mentioned S1.

[0057] Step (3): Prepare a protective film layer 3 on the surface of the bottom reflective metal film layer 2. The main function of the protective film layer 3 is to protect the bottom metal film layer 2 from being damaged by subsequent corrosion or development process. The thickness of the protective film layer 3 is d2 = 2 to 20 nm; equivalent to the above S2.

[0058] Step (4): preparing a photosensitive film layer 4 on the protective film layer 3, wherein the thickness of the photosensitive film layer 4 is d3 = 10-200 nm; equivalent to the above-mentioned S3.

[0059] Step (5): prepare a transparent protective film layer 5 on the photosensitive film layer 4. The transparent protective film layer 5 is mainly used to protect the photosensitive film layer 4 from being damaged by the subsequent corrosion process. The thickness of the transparent protective film layer 5 is d4 = 2 to 10 nm; this is equivalent to the above S4.

[0060] Step (6): prepare a surface transmissive metal film layer 6 on the transparent protective film layer 5 to form a metal-photosensitive film layer-metal plasma cavity imaging structure, and the thickness of the surface transmissive metal film layer 6 is d5 = 10 to 30 nm; equivalent to the above S5.

[0061] At this point, the method for protecting the imaging structure of plasma resonance cavity lens lithography has been completed, and then the obtained imaging structure of plasma resonance cavity lens lithography is used to perform subsequent exposure and development steps.

[0062] Step (7): Using super-resolution lithography technology, an exposure process is carried out on the plasma cavity imaging structure, and the mask pattern feature size d6 is used = 20-100nm. This step can use an ultraviolet 365nm illumination light source, an ultraviolet 193nm illumination light source, or an ultraviolet illumination light source of other wavelengths. The mask pattern structure can be a one-dimensional pattern or a two-dimensional pattern structure.

[0063] Step (8): wet-etch the surface transmissive metal film layer 6 of the plasma cavity imaging structure after exposure in step (7), and the etching solution used is a solution that can react with metal, which can be an acidic solution or an alkaline solution. The etching solution in this step can be a nitric acid solution, a chromium removal solution, or other chemical solutions that react with metals; the etching solution cannot produce other impurities after reacting with the metal, and the products after the reaction can be washed away by pure water.

[0064] Step (9): Use an etching process to remove the transparent protective film layer 5. This step uses a process for etching the protective layer, which can be achieved by ion beam etching, reactive ion beam etching, or inductively coupled plasma etching (ICP). The selected etching gas can be SF6, CHF3, O2, or Ar.

[0065] Step (10): Use a developer to develop the pattern in the photosensitive film layer 4, and complete the processing of the super-resolution photolithography pattern structure. The photolithography pattern can be a one-dimensional pattern or a two-dimensional pattern, and the pattern feature size d7 = 20-100nm. In the development process of this step, the photosensitive film layer 4 can be immersed in the developer for development, or the photosensitive film layer 4 can be sprayed with the developer. The developer can be an AR series, AZ series or other ultraviolet series photoresist special developer, and the developer only develops the photosensitive pattern and has no destructive effect on the underlying protective film layer 3. In this way, the protective film layer 3 plays a role in protecting the underlying reflective metal film layer 2.

[0066] Specifically, the following 3 embodiments and 2 comparative examples are provided:

[0067] Embodiment 1:

[0068] like Figure 1 As shown, the imaging structure protection method and subsequent exposure and development method of the plasma resonance cavity lens lithography disclosed in the present invention have the following specific implementation steps:

[0069] (11) Figure 2As shown, the imaging substrate 1 material is quartz substrate material; the bottom reflective metal film layer 2 is an Ag film layer with a thickness of 30nm; the protective film layer 3 is a SiO2 film layer with a thickness of 2nm, and its preparation method is magnetron sputtering coating; the photosensitive film layer 4 is an AR-P3170 photoresist layer with a film thickness of 20nm; the transparent protective film layer 5 is a SiO2 film layer with a thickness of 5nm, and its preparation method is electron beam evaporation coating; the surface transmission metal film layer 6 material is Ag with a thickness of 16nm, and its preparation method is thermal evaporation coating; the mask light blocking layer 7 material is metal Cr with a thickness of 40nm, and magnetron sputtering coating is adopted, and the coating temperature is 400℃; the mask graphic structure 8 is a grating graphic structure with a half-period of 32nm; the mask substrate 9 is a quartz substrate; the illumination incident light 10 is ultraviolet light with a wavelength of 365nm.

[0070] (12) Figure 3 As shown, after super-resolution lithography exposure, the surface transmissive metal film layer 6 is wet-etched with nitric acid etching solution. The concentration of the nitric acid etching solution used is 20%, the etching temperature is 22°C, and the etching time is 10s. After etching, it is rinsed with deionized water. Since SiO2 material does not react with nitric acid solution, when the surface transmissive metal film layer 6 (Ag film layer) is etched with nitric acid, the transparent protective film layer 5 (SiO2 film layer) can well protect the photosensitive film layer 4. The structure after etching is as shown in FIG. Figure 4 as shown; Figure 5 As shown, the transparent protective film layer 5 is removed by ion beam etching, the gas used is Ar, and the etching power is 5w; Figure 6 , AR300-35 developer is used to develop the photosensitive film layer 4, the development time is 20s, and the development temperature is 0°C. Since the developer will cause certain damage to the underlying reflective metal film layer 2 (Ag film layer) during the development process, it will often destroy the entire resonant cavity imaging structure. When a 2nm transparent protective film layer 5 (SiO2 film layer) is added to the surface of the underlying reflective metal film layer 2 (Ag film layer), the damage of the developer to the underlying reflective metal film layer 2 (Ag film layer) can be solved, thereby ensuring the quality of the imaging pattern; the resonant cavity imaging structure designed in this embodiment obtains a clear 32nm resolution pattern in super-resolution lithography, and the pattern contrast reaches more than 0.7, such as Figure 7 As shown, Figure 7 (a) is the light field simulation diagram of the 32nm resolution pattern obtained. Figure 7 (b) is the light field distribution curve at the middle depth of the photosensitive layer. At the same time, the 32nm resolution pattern obtained by the exposure and development process is shown in Figure 8 As shown, the effectiveness of the protective film layer and the transparent protective film layer disclosed in the present invention is proved.

[0071] Embodiment 2:

[0072] like Figure 1 As shown, the imaging structure protection method and subsequent exposure and development method of the plasma resonance cavity lens lithography disclosed in the present invention have the following specific implementation steps:

[0073] (21) Figure 2 As shown, the imaging substrate 1 material is quartz substrate material; the bottom reflective metal film layer 2 is an Al film layer with a thickness of 40nm; the protective film layer 3 is a MgF2 film layer with a thickness of 3nm, and its preparation method is magnetron sputtering coating; the photosensitive film layer 4 is a PHS photoresist layer with a film thickness of 30nm; the transparent protective film layer 5 is a SiO2 film layer with a thickness of 5nm, and its preparation method is electron beam evaporation coating; the surface transmission metal film layer 6 material is Al with a thickness of 16nm, and its preparation method is thermal evaporation coating; the mask light blocking layer 7 material is metal Mo with a thickness of 40nm, and magnetron sputtering coating is adopted, and the coating temperature is 380℃; the mask graphic structure 8 is a grating graphic structure with a half-period of 44nm; the mask substrate 9 is a quartz substrate; the illumination incident light 10 is ultraviolet light with a wavelength of 365nm.

[0074] (22) Figure 3 As shown, after super-resolution lithography exposure, the surface transmissive metal film layer 6 (Al film layer) is wet-etched using phosphoric acid etching solution. The concentration of the phosphoric acid etching solution used is 55%, the etching temperature is 22°C, and the etching time is 20s. After etching, it is rinsed with deionized water. Since SiO2 material does not react with phosphoric acid solution, when phosphoric acid is used to etch the surface transmissive metal film layer 6 (Al film layer), the transparent protective film layer 5 (SiO2 film layer) can well protect the photosensitive film layer 4. The structure after etching is as shown in FIG. Figure 4 as shown; Figure 5 As shown, the transparent protective film layer 5 (SiO2 film layer) is removed by reactive ion beam etching, the gas used is CHF3, and the etching power is 5W; Figure 6 The photosensitive film layer 4 is developed with TMAH developer for 30 seconds at a temperature of 20°C. During the development process, the developer will cause certain damage to the underlying reflective metal film layer 2 (Al film layer), which will often destroy the entire resonant cavity imaging structure. When a 3nm protective film layer 3 (MgF2 film layer) is added to the surface of the underlying reflective metal film layer 2 (Al film layer), the damage to the underlying reflective metal film layer 2 (Al film layer) by the developer can be solved, thereby ensuring the quality of the imaging pattern.

[0075] Embodiment 3:

[0076] like Figure 1 As shown, the imaging structure protection method and subsequent exposure and development method of the plasma resonance cavity lens lithography disclosed in the present invention have the following specific implementation steps:

[0077] (31) Figure 2 As shown, the imaging substrate 1 material is silicon substrate material; the bottom reflective metal film layer 2 is an Ag film layer with a thickness of 40nm; the protective film layer 3 is an Al2O3 film layer with a thickness of 2nm, and its preparation method is thermal evaporation coating; the photosensitive film layer 4 is an AR-P3120 photoresist layer with a film thickness of 20nm; the transparent protective film layer 5 is a SiO2 film layer with a thickness of 5nm, and its preparation method is electron beam evaporation coating; the surface transmission metal film layer 6 material is Al with a thickness of 20nm, and its preparation method is thermal evaporation coating; the mask light blocking layer 7 material is metal Cr with a thickness of 50nm, and magnetron sputtering coating is adopted, and the coating temperature is 420℃; the mask graphic structure 8 is a grating graphic structure with a half-period of 45nm; the mask substrate 9 is a sapphire substrate; the illumination incident light 10 is ultraviolet light with a wavelength of 365nm.

[0078] (32) Figure 3 As shown, after super-resolution lithography exposure, the surface transmissive metal film layer 6 (Al film layer) is wet-etched using phosphoric acid etching solution. The concentration of the phosphoric acid etching solution used is 60%, the etching temperature is 40°C, and the etching time is 15s. After etching, it is rinsed with deionized water. Since SiO2 material does not react with phosphoric acid solution, when phosphoric acid is used to etch the surface transmissive metal film 6 (Al film layer), the transparent protective film layer 5 (SiO2 film layer) can well protect the photosensitive film layer 4. The structure after etching is as shown in FIG. Figure 4 as shown; Figure 5 As shown, the transparent protective film layer 5 (SiO2 film layer) is removed by ion beam etching, the gas used is Ar, and the etching power is 15W; Figure 6 The photosensitive film layer 4 is developed with AR300-35 developer for 50s at a temperature of 0°C. During the development process, the developer will cause certain damage to the underlying reflective metal film layer 2 (Ag film layer), which will often destroy the entire resonant cavity imaging structure. When a 2nm protective film layer 3 (Al2O3 film layer) is added to the surface of the underlying reflective metal film layer 2 (Ag film layer), the damage of the developer to the underlying reflective metal film layer 2 (Ag film layer) can be solved, thereby ensuring the quality of the imaging pattern.

[0079] Comparative Example 1: No protective film layer 3 and transparent protective film layer 5.

[0080] like Figure 1 As shown, the imaging structure protection method and subsequent exposure and development method of the plasma resonance cavity lens lithography disclosed in the present invention have the following specific implementation steps:

[0081] (41) Figure 2As shown, the imaging substrate 1 is made of quartz substrate material; the bottom reflective metal film layer 2 is an Ag film layer with a thickness of 30nm; the photosensitive film layer 4 is an AR-P 3170 photoresist layer with a thickness of 20nm; the surface transmissive metal film layer 6 is made of Ag with a thickness of 16nm, and its preparation method is thermal evaporation coating; the mask light-blocking layer 7 is made of metal Cr with a thickness of 40nm, and is coated by magnetron sputtering at a coating temperature of 400°C; the mask graphic structure 8 is a grating graphic structure with a half-period of 32nm; the mask substrate 9 is a quartz substrate; and the illumination incident light 10 is ultraviolet light with a wavelength of 365nm.

[0082] (42) After super-resolution lithography exposure, the surface transmissive metal film layer 6 (Ag film layer) is wet-etched using nitric acid etching solution. The concentration of the nitric acid etching solution used is 20%, the etching temperature is 22°C, and the etching time is 10s. After etching, it is rinsed with deionized water. It can be found that in the absence of the protective film layer 3 and the transparent protective film layer 5, the process of removing the surface transmissive metal film layer 6 (Ag film layer) using nitric acid has corroded and damaged the entire photosensitive film layer 4 and part of the bottom reflective metal film layer 2 (Ag film layer), such as Fig. 9 It is impossible to continue with the subsequent development process, so it can be proved that the super-diffraction pattern cannot be obtained without the protective film layer 3 and the transparent protective film layer 5.

[0083] Comparative Example 2: with protective film layer 3 but without transparent protective film layer 5.

[0084] like Figure 1 As shown, the present invention discloses a method for protecting an imaging structure in plasma resonance cavity lens lithography and a subsequent exposure and development method, and the specific implementation steps are as follows:

[0085] (51) Figure 2 As shown, the imaging substrate 1 material is a quartz substrate material; the bottom reflective metal film layer 2 is an Al film layer with a thickness of 40nm; the protective film layer 3 is a MgF2 film layer with a thickness of 3nm, and its preparation method is magnetron sputtering coating; the photosensitive film layer 4 is a PHS photoresist layer with a film thickness of 30nm; the surface transmission metal film layer 6 material is Al with a thickness of 16nm, and its preparation method is thermal evaporation coating; the mask light blocking layer 7 material is metal Mo with a thickness of 40nm, and magnetron sputtering coating is adopted, and the coating temperature is 380℃; the mask graphic structure 8 is a grating graphic structure with a half-period of 44nm; the mask substrate 9 is a quartz substrate; the illumination incident light 10 is ultraviolet light with a wavelength of 365nm.

[0086] (52) Figure 3As shown, after super-resolution lithography exposure, the surface transmissive metal film layer 6 (Al film layer) is wet-etched using phosphoric acid etching solution. The concentration of the phosphoric acid etching solution used is 55%, the etching temperature is 22°C, and the etching time is 20s. After etching, it is rinsed with deionized water. The results after etching and cleaning are shown in FIG. Fig.10 As shown. After the corrosion, the PHS photoresist layer on the entire substrate has been completely corroded, and only a small amount of residual photosensitive layer is left, and subsequent process flows such as development cannot be performed. Therefore, when there is only a protective film layer 3 and no transparent protective film layer 5, the corrosion process will destroy the photosensitive film layer 4, so that the super-diffraction lithography pattern cannot be obtained. Of course, if there is only a transparent protective film layer 5 and no protective film layer 3, during the development process, the developer material will destroy the underlying reflective metal film layer 2, and the super-diffraction lithography pattern cannot be obtained either. Therefore, when there is only a transparent protective film layer 5 or a protective film layer 3, a complete super-diffraction lithography pattern still cannot be obtained.

[0087] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A method for protecting an imaging structure of a plasma resonance cavity lens lithography, characterized in that: include: S1, depositing a reflective metal film layer (2) on the surface of a substrate (1); S2, depositing a protective film layer (3) on the reflective metal film layer (2), wherein the protective film layer (3) is used to protect the reflective metal film layer (2); S3, preparing a photosensitive film layer (4) on the protective film layer (3); S4, depositing a transparent protective film layer (5) on the photosensitive film layer (4), wherein the transparent protective film layer (5) is used to protect the photosensitive film layer (4); the transparent protective film layer (5) is a transparent medium material; S5, depositing a transmissive metal film layer (6) on the transparent protective film layer (5) to obtain an imaging structure of a plasma resonance cavity lens lithography; In the process of wet removal of the surface metal, the transparent protective film layer (5) is used to protect the reflective metal film layer (2) and the photosensitive film layer (4) to avoid being damaged by the corrosive solution; in the process of developing the photosensitive film layer (4), the protective film layer (3) is used to protect the reflective metal film layer (2) to avoid being damaged by the developer; the transparent protective film layer (5) and the protective film layer (3) cooperate to protect the integrity of the imaging structure; The protective film layer (3) comprises one of SiO2, Al2O3, and MgF2, and the thickness of the protective film layer (3) is 2 to 3 nm; The transparent protective film layer (5) is SiO2 and has a thickness of 5 nm.

2. The imaging structure protection method of plasma resonance cavity lens lithography according to claim 1, characterized in that: The substrate (1) in S1 comprises one of a silicon substrate, a quartz substrate, a magnesium fluoride substrate and a flexible substrate.

3. The imaging structure protection method of plasma resonance cavity lens lithography according to claim 2, characterized in that: The method of depositing the reflective metal film layer (2) in S1 comprises one of magnetron sputtering deposition, thermal evaporation deposition or chemical vapor deposition; The reflective metal film layer (2) comprises one of Ag, Al and Au.

4. The imaging structure protection method of plasma resonance cavity lens lithography according to claim 1, characterized in that: The method for depositing the protective film layer (3) in S2 comprises one of magnetron sputtering deposition, atomic layer deposition, chemical vapor deposition and vacuum evaporation deposition.

5. The imaging structure protection method of plasma resonance cavity lens lithography according to claim 1, characterized in that: The photosensitive film layer (4) in S3 comprises one of a UV phenolic resin system photoresist, a polystyrene system photoresist, and a molecular glass system photoresist.

6. The imaging structure protection method of plasma resonance cavity lens lithography according to claim 1, characterized in that: The method for depositing the transparent protective film layer (5) in S4 comprises one of magnetron sputtering deposition, atomic layer deposition, chemical vapor deposition and vacuum evaporation deposition.

7. The imaging structure protection method of plasma resonance cavity lens lithography according to claim 1, characterized in that: The method of depositing the transmissive metal film layer (6) in S5 comprises one of magnetron sputtering deposition, atomic layer deposition, chemical vapor deposition and vacuum evaporation deposition; The transmissive metal film layer (6) comprises one of Ag, Al and Au.

8. An imaging structure for plasma resonance cavity lens lithography, characterized in that: The imaging structure is prepared by using the imaging structure protection method of plasma resonance cavity lens lithography according to any one of claims 1 to 7.

9. Application of the imaging structure of plasma resonance cavity lens lithography according to claim 8 in surface plasmon super-resolution imaging lithography.

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