Contrast-optimized anti-pollution medium-filled mask and preparation method thereof
Through simulation optimization of the deposition of ultralens and fill media in the mask slit, combined with annealing and planarization, the problems of traditional masks being susceptible to contamination and low contrast are solved, and higher anti-pollution ability and lithographic contrast are achieved , improve structural resolution and production efficiency.
Patent Information
- Application Number
- CN202411664465.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-20
- Publication Date
- 2024-12-27
AI Technical Summary
Traditional masks are susceptible to contamination and low lithography contrast, especially in plasma lithography technology, where imaging quality declines due to small micro-scale contaminants and slit sizes.
Through simulation calculation, optimize the key film parameters and fill media of superlens, simulate the contrast curves of different refractive index media, select appropriate fill media and deposit them in the mask slit, combine annealing and planarization to prepare anti-pollution media to be prepared Fill the mask.
It significantly improves the mask's anti-pollution ability and lithographic contrast, achieves higher resolution structural preparation, reduces chip manufacturing costs, improves product yields, and simplifies the preparation process.
Smart Images
Figure CN119200321A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the technical field of photolithography, and in particular to a contrast-optimized anti-pollution medium-filled mask and a preparation method thereof. Background Art
[0002] Surface Plasmon (SP) lithography technology is based on superlens and mainly uses evanescent waves (light waves that decay rapidly away from the surface) for imaging, bypassing the diffraction limit of imaging resolution of about half a wavelength in traditional optical systems, thereby achieving proportional graphic imaging of sub-wavelength size.
[0003] As a proximity exposure technology, SP lithography has a working distance of only nanometers and is easily contaminated by pollutants in practical applications. These micro-scale pollutants will have a serious negative impact on the image quality, thereby reducing the contrast and clarity of the image. Therefore, in order to maintain high-quality lithography effects, appropriate anti-pollution measures need to be added to the process flow to minimize the impact of pollutants on plasma lithography and ensure the efficiency and accuracy of the lithography process.
[0004] In addition, as the circuit pattern becomes finer and the period and line width of the mask gradually decrease, the scattering and reflection effects increase during the interaction between the UV light and the mask material, resulting in a decrease in the light flux concentrated through the mask slit, thereby reducing the contrast of the exposure pattern. At the same time, the interference effect when the light wave passes through the narrow slit also becomes significant, forming interference fringes or other irregular exposure patterns and blurred pattern edges on the wafer, which further reduce the exposure contrast. In addition, for masks with smaller periods (< ~100 nm) and smaller slits (< ~28 nm), any slight unevenness in the mask material (such as slight changes in thickness or refractive index) may have a significant impact on the exposure contrast.
[0005] Therefore, it is necessary to provide an anti-pollution method or technology for a lithography mask, and the technology should be able to achieve a lithography effect with higher contrast in SP lithography. Summary of the invention
[0006] 1. Technical issues to be resolved
[0007] In view of the above problems, the present disclosure provides a contrast-optimized anti-pollution medium-filled mask and a preparation method thereof, which are used to solve technical problems such as the traditional mask being easily contaminated and having low lithography contrast.
[0008] (II) Technical solution
[0009] An aspect of an embodiment of the present disclosure provides a method for preparing a contrast-optimized anti-pollution medium-filled mask, comprising: S1, performing simulation calculations according to mask conditions to obtain optimized superlens key film layer parameters; S2, simulating the graphic structure of the mask with different refractive index media and filling the simulated structure according to the optimized superlens key film layer parameters to obtain a contrast curve; S3, determining a contrast-optimized filling medium adapted to an actual working environment according to the contrast curve; S4, preparing the graphic structure of the mask according to the mask conditions, and filling the graphic structure with the optimal filling medium determined in S3; S5, annealing and flattening the mask obtained in S4 in sequence to obtain a contrast-optimized anti-pollution medium-filled mask.
[0010] According to an embodiment of the present disclosure, the method for performing simulation calculation in S1 includes any one of a rigorous coupled wave analysis method, a finite difference time domain method, and a finite element method.
[0011] According to an embodiment of the present disclosure, the key film layer parameters of the superlens in S1 include at least the material and thickness of the metal transmission layer and the photoresist layer; wherein the material of the metal transmission layer includes any one of Au, Ag, Al, and Cu; and the material of the photoresist layer includes any one of the AR series, AZ series, and PMMA series photosensitive materials.
[0012] According to an embodiment of the present disclosure, the refractive index of the different refractive index media used for simulation in S2 is 1-10; the different refractive index media include the different refractive index media including SiO 2 、Si 3 N 4 , HfO 2 、TiO 2 、Al 2 O 3 、ZrO 2 、 2 O 5 , Nb 2 O 5 , WO 3 , AlAs, ZnS, TiN and TaN.
[0013] According to an embodiment of the present disclosure, S3 includes: determining, according to the contrast curve, a material that is higher than the contrast baseline when there is no filling and that can adapt to the actual working environment as the filling medium.
[0014] According to an embodiment of the present disclosure, preparing the graphic structure of the mask plate according to the mask conditions in S4 includes: depositing a photolithography mask material on the substrate of the mask plate, and preparing graphic structures of different periods and line widths by photolithography and etching methods; wherein the photolithography method includes any one of surface plasma lithography, electron beam direct writing lithography, and projection lithography; the etching method includes any one of ion beam etching, reactive ion beam etching, inductively coupled plasma etching, and capacitively coupled high energy plasma etching.
[0015] According to an embodiment of the present disclosure, the base material of the mask in S4 includes any one of sapphire, quartz, silicon, and magnesium fluoride; the photolithography mask material includes any one of Cr, Ta, and Mo.
[0016] According to an embodiment of the present disclosure, the method of filling the filling medium determined in S3 in S4 includes any one of vacuum evaporation deposition, magnetron sputtering deposition, atomic layer deposition, and chemical vapor deposition, wherein the surface of the filling medium is higher than the surface of the graphic structure of the mask.
[0017] According to an embodiment of the present disclosure, the annealing temperature in S5 is 100°C to 1000°C, the heating rate is 10°C to 100°C / minute, the cooling rate is 10°C to 50°C / minute, and the holding time is 0.5 to 10 hours; the planarization method in S5 includes any one of ion beam etching and chemical mechanical polishing, wherein the surface of the filling medium after planarization is flush with the surface of the graphic structure of the mask.
[0018] Another aspect of the embodiments of the present disclosure provides a contrast-optimized anti-pollution medium-filled mask, which is prepared by using the above-mentioned method for preparing a contrast-optimized anti-pollution medium-filled mask.
[0019] (III) Beneficial effects
[0020] The contrast-optimized anti-pollution medium-filled mask and preparation method disclosed herein determine the optimized key film layer parameters of the metalens and the appropriate filling medium through numerical simulation, and coordinate the type and properties of the medium material used to fill the mask slits with the specific mask slit design, size, shape and arrangement to achieve the effect of improving the anti-pollution ability of the mask and the lithography contrast, and realize higher-resolution structure preparation; at the same time, reduce the manufacturing cost of the chip, improve the product yield, and greatly simplify the overall preparation process. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 A flow chart schematically shows a method for preparing a contrast-optimized anti-pollution medium-filled mask according to an embodiment of the present disclosure;
[0022] Figure 2 A schematic diagram of the structure of a superlens in SP lithography according to one of the embodiments of the present disclosure is shown;
[0023] Figure 3 Schematically showing contrast curves when medium is filled under different masks and slit widths according to the embodiment of the present disclosure;
[0024] Figure 4 A structural flow chart of a contrast-optimized anti-pollution medium-filled mask according to an embodiment of the present disclosure is schematically shown;
[0025] Figure 5 Schematically showing a cross-sectional view of a dielectric-filled mask before and after planarization according to an embodiment of the present disclosure;
[0026] Figure 6 It shows that SiO 2 Comparison of the mask before and after filling and the corresponding exposure pattern (period 105 nm / line width 25 nm, period 90 nm / line width 20 nm).
[0027] Description of Figure Numbers:
[0028] 1. Mask substrate; 2. Photolithography mask material; 3. Photoresist layer; 4. Optimal filling medium; 5. Cavity. DETAILED DESCRIPTION
[0029] 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.
[0030] 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.
[0031] 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.
[0032] The present invention provides a method for preparing a contrast-optimized anti-pollution medium-filled mask. Figure 1 A flowchart schematically shows a method for preparing a contrast-optimized anti-pollution dielectric-filled mask according to an embodiment of the present disclosure, see Figure 1The preparation method may include: S1, performing simulation calculation according to mask conditions to obtain optimized superlens key film layer parameters; S2, simulating the filling of the mask pattern structure with different refractive index media according to the optimized superlens key film layer parameters and performing simulation to obtain a contrast curve; S3, determining the contrast-optimized filling medium adapted to the actual working environment according to the contrast curve; S4, preparing the mask pattern structure according to the mask conditions, and filling the optimal filling medium determined in S3 into the pattern structure; S5, annealing and flattening the mask obtained in S4 in turn to obtain a contrast-optimized anti-pollution medium-filled mask.
[0033] This preparation method determines the optimized key film layer parameters of the superlens and the appropriate filling medium through numerical simulation, and coordinates the type and properties of the dielectric material used to fill the mask slits with the specific mask slit design, size, shape and arrangement. Specific media are selected to fill the slits of the mask. On the one hand, it can improve the tolerance of the mask to contaminants in SP lithography, and on the other hand, it optimizes the propagation characteristics of light, suppresses unnecessary diffraction and scattering, and significantly improves its lithography contrast. At the same time, it reduces the manufacturing cost of the chip, improves the product yield, and greatly simplifies the overall preparation process.
[0034] On the basis of the above embodiment, the method for performing simulation calculation in S1 may include any one of a rigorous coupled wave analysis method, a finite difference time domain method, and a finite element method.
[0035] In steps S1 and S2, the simulation can be calculated using methods such as Rigorous Coupled Wave Analysis (RCWA), Finite Difference Time Domain (FDTD), and Finite Element Method (FEM). In actual use, the impact of simulation accuracy should be carefully considered.
[0036] On the basis of the above embodiments, the key film layer parameters of the superlens in S1 may at least include the material and thickness of the metal transmission layer and the photoresist layer; wherein the material of the metal transmission layer may include any one of Au, Ag, Al, and Cu; and the material of the photoresist layer may include any one of AR series, AZ series, and PMMA series photosensitive materials.
[0037] The film layers of the super lens in S1 may include a mask, an air spacer layer, a metal transmission layer, a photoresist layer, a metal reflection layer and a substrate layer. Figure 2 The schematic diagram of the structure of a super lens in SP lithography according to one embodiment of the present disclosure is shown as follows: Figure 2 As shown, the superlens structure may include a mask (SiO2 Substrate + Cr photolithography mask material), air spacer layer (Air), metal transmission layer (Ag), photoresist layer (Pr), metal reflection layer (Ag) and substrate (Si). The optimized parameters of the superlens in S1 include at least the metal transmission layer and the photoresist layer, among which the metal transmission layer should be a plasma material that can produce significant plasma resonance under the irradiation of ultraviolet light, and the photoresist layer should have good adhesion on the metal surface; the thickness of the metal transmission layer should be controlled to achieve better light transmission performance, and the high purity of the photoresist layer should be electronic grade or above. In the process of optimizing the parameters of the metal transmission layer and the photoresist layer, the actual process limitations and requirements (including the type of thin film deposition source material, acid and alkali resistance, high temperature and high mechanical properties, etc.) should be considered to obtain the optimal parameter combination.
[0038] Based on the above embodiment, the refractive index of the medium with different refractive indexes used for simulation in S2 may be 1 to 10; the medium with different refractive indexes may include SiO 2 、Si 3 N 4 , HfO 2 、TiO 2 、Al 2 O 3 、ZrO 2 、 2 O 5 , Nb 2 O 5 , WO 3 , AlAs, ZnS, TiN and TaN.
[0039] In S2, simulation is performed to obtain contrast curves under different refractive index (1~10) filling media. The filled transparent medium material should have the characteristics of high strength, high transmittance in the ultraviolet band and high purity. The actual filling medium can be the common process material SiO 2 、Si 3 N 4 , HfO 2 、TiO 2 、Al 2 O 3 、ZrO 2 、 2 O 5 , Nb 2 O 5 , WO 3 , AlAs, ZnS, TiN and TaN, and the deposition method can be vacuum evaporation deposition, magnetron sputtering deposition, atomic layer deposition, and chemical vapor deposition, wherein the surface of the filling medium is higher than the surface of the graphic structure of the mask.
[0040] On the basis of the above embodiment, S3 may include: determining a contrast-optimized filling medium adapted to the actual working environment according to the contrast curve.
[0041] Figure 3 The figure schematically shows the contrast curves when the medium is filled under different masks and slit widths according to the embodiment of the present disclosure. Figure 3 As shown, the horizontal axis is the refractive index and the vertical axis is the contrast. Figure 3 The middle horizontal dotted line represents the contrast baseline when there is no filling. The refractive index of the actual filling medium material should be selected to be higher than the contrast baseline when there is no filling (corresponding to the contrast when there is no filling, that is, the refractive index is 1). At the same time, consider whether the filled material is suitable for the actual working environment, such as high temperature resistance and acid and alkali resistance.
[0042] Different from traditional optimization techniques, the present invention can effectively improve the lithography contrast by filling a specific filling medium in the slits of the mask, thereby achieving higher-resolution structure preparation; the contrast is improved by changing the filling medium rather than complex equipment or special treatment, which greatly simplifies the overall preparation process.
[0043] On the basis of the above-mentioned embodiments, preparing the graphic structure of the mask plate according to the mask conditions in S4 may include: depositing a photolithography mask material on the substrate of the mask plate, and preparing graphic structures of different periods and line widths by photolithography and etching methods; wherein the photolithography method includes any one of surface plasma lithography, electron beam direct writing lithography, and projection lithography; the etching method includes any one of ion beam etching, reactive ion beam etching, inductively coupled plasma etching, and capacitively coupled high energy plasma etching.
[0044] The preparation of the graphic structure of the mask plate includes first depositing the photolithography mask material on the substrate of the mask plate. The method of depositing the photolithography mask material can be sputtering deposition, evaporation deposition, atomic layer deposition, chemical vapor deposition, etc.; and then using various photolithography or etching methods to prepare the graphic structure. The photolithography method can be surface plasma lithography technology, electron beam direct writing lithography technology, 193 nm projection lithography, etc., to ensure the high-precision preparation of small-period masks. In S3, reactive ion beam etching (RIE), inductively coupled plasma etching (ICP) or capacitively coupled high-energy plasma etching (CCP) methods are usually used for quartz substrates and glass substrates, reactive ion beam etching (RIE) or ion beam etching (IBE) methods are usually used for sapphire substrates, and reactive ion beam etching (RIE) and inductively coupled plasma etching (ICP) methods are used for organic film substrates.
[0045] On the basis of the above embodiment, the base material of the mask in S4 may include any one of sapphire, quartz, silicon, and magnesium fluoride; the photolithography mask material may include any one of Cr, Ta, and Mo.
[0046] The base material of the mask in S4 can be sapphire, quartz, silicon, magnesium fluoride and other materials, and the base should have good flatness and stability. The method of depositing the photolithography mask material can be sputtering deposition, evaporation deposition, atomic layer deposition, chemical vapor deposition and other methods. The photolithography mask material can be Cr, Ta, Mo or other hard metals with a thickness of 50 nm ~ 500 nm. The specific thickness of the photolithography mask material is determined according to the light absorption performance of the film material, and its transmittance is required to be less than 0.5%; the photolithography mask should have good light absorption characteristics. The difference in dielectric constants of different film layers will lead to differences in the film parameters of the super lens and the best actual filling material, but the specific simulation settings, steps and the method of determining the best actual filling material are consistent.
[0047] Based on the above embodiment, the method of filling the filling medium determined in S3 in S4 may include any one of vacuum evaporation deposition, magnetron sputtering deposition, atomic layer deposition, and chemical vapor deposition.
[0048] SiO 2 、Si 3 N 4 , HfO 2 、TiO 2 、Al 2 O 3 、ZrO 2 、 2 O 5 , Nb 2 O 5 , WO 3 , AlAs, ZnS, TiN and TaN can be filled by deposition method, and the surface of the filling medium is higher than the surface of the graphic structure of the mask to achieve complete coverage of the mask graphic structure.
[0049] Based on the above embodiment, the annealing temperature in S5 can be 100°C to 1000°C, the heating rate can be 10°C to 100°C / minute, the cooling rate can be 10°C to 50°C / minute, and the insulation time can be 0.5 to 10 hours; the planarization method in S5 includes any one of ion beam etching and chemical mechanical polishing.
[0050] The mask can be annealed as a whole, which means putting the entire mask substrate including the transparent dielectric material into an annealing device for annealing; or only the upper surface of the mask with the transparent dielectric material can be annealed, which means heating only the substrate of the mask and the upper surface of the transparent dielectric material, while the back of the substrate of the mask is not heated for annealing. Annealing the mask can reduce the cavities in the transparent dielectric material, further adjust the dielectric constant of the filling medium, and improve its optical and mechanical properties.
[0051] In S5, an etching or planarization process is used to planarize the film layer, so that the planarized filling medium surface is flush with the mask pattern structure surface, and finally a contrast-optimized anti-pollution medium filling mask is obtained.
[0052] The present invention first uses simulation technology to determine the key film layer parameters of the metalens under different parameter mask conditions, then fills the media with different refractive indexes under the optimized key film layer parameters under different parameter mask conditions, and finally selects the appropriate filling medium based on the simulation contrast curve and the actual process conditions to provide a priori guidance for subsequent experiments; based on the mask graphic structure, the optimal filling medium is filled in the mask slit through the material filling technology and annealed and flattened to obtain a contrast-optimized anti-pollution medium-filled mask.
[0053] Filling the mask with the optimal filling medium can, on the one hand, prevent contaminant particles from falling into the mask slits and reduce the impact of contaminants on imaging; on the other hand, it can also improve the lithography contrast and help achieve high-precision pattern transfer; in addition, through annealing treatment, the bonding force between the optimal filling medium and the mask is enhanced, the pinhole bubbles inside the optimal filling medium are reduced, the stress inside the optimal filling medium is eliminated, and its high-temperature tolerance is improved, thereby improving the uniformity and thermal stability of the overall structure of the mask; the flattening treatment further ensures the uniformity and smoothness of the mask surface, which helps to improve the lithography accuracy and consistency.
[0054] The present disclosure also provides a contrast-optimized anti-pollution medium-filled mask, which is prepared by the aforementioned method for preparing the contrast-optimized anti-pollution medium-filled mask.
[0055] The present invention provides a contamination-resistant medium-filled mask with optimized contrast in SP lithography and a preparation method thereof, which overcomes the problem of limited exposure contrast due to the mask being susceptible to contamination and the small slit size in SP lithography, and achieves excellent anti-pollution performance and a lithography effect with higher contrast.
[0056] The present disclosure is further described below through specific implementations. The above-mentioned contrast-optimized anti-pollution dielectric filling mask and its preparation method are specifically described in the following examples. However, the following examples are only used to illustrate the present disclosure, and the scope of the present disclosure is not limited thereto.
[0057] The method for preparing the anti-pollution medium-filled mask with optimized contrast in the following embodiment comprises the following steps:
[0058] Step (1): Use simulation technology to scan the influence of the key film layer parameters of the superlens on the contrast under different parameter mask conditions, and obtain the optimized key film layer parameter combination of the superlens. Among them, the key film layer parameters of the superlens include at least the material and thickness of the metal transmission layer and the photoresist layer; the scanning range of the metal transmission layer is 8~36 nm, and the thickness of the photoresist layer is 20~46 nm; the mask period is 105 nm and 90 nm, and the corresponding mask slit width is 25 nm and 20 nm. In the process of optimizing the parameters of the metal transmission layer and the photoresist layer, refer to the contrast hot spot map and the actual process limitations: the metal transmission layer is greater than 10 nm, and the photoresist layer thickness is greater than 20 nm. Finally, the optimized key film layer parameter combination of the superlens under different period and line width mask layers is obtained. Equivalent to the above S1.
[0059] Step (2): Fill the medium with different refractive indexes under the optimized key film layer parameters under different parameter mask conditions, and finally select the appropriate filling medium based on the simulated contrast curve and the actual process conditions. Figure 3 As shown, Figure 3 (a)-(c) in the figure show the contrast curves of different Cr, Ta, and Mo mask periods (105 nm, 90 nm) and corresponding slit widths (25 nm, 20 nm) under different simulated filling refractive index (1~10) filling media. The horizontal dotted line in the figure represents the contrast baseline when there is no filling, and the vertical dotted line corresponds to the refractive index of the ideal filling medium. For the Cr mask, the refractive index of the filling medium above the baseline ranges from 1~6.2 (period 105 nm) and 1~5.4 (period 90 nm); for the Ta mask, the refractive index of the filling medium above the baseline ranges from 1~5.2 (period 105 nm) and 1~3.7 (period 90 nm); for the Mo mask, the refractive index of the filling medium above the baseline ranges from 1~1.6, 3.5~4.3 and 7.0~7.6 (period 105 nm), 1~3.8 and 4.8~7.0 (period 90 nm). Equivalent to S2~S3 above.
[0060] Step (3): Deposit a photolithography mask material on the substrate of the mask plate, and use photolithography and etching techniques to complete the preparation of graphic structures of different periods and line widths through steps such as coating and developing.
[0061] Figure 4 The structural flow chart of the anti-pollution medium filling mask with optimized contrast according to the embodiment of the present disclosure is schematically shown. Figure 4 As shown, the preparation of the graphic structure may include:
[0062] Step (31): Prepare a photolithography mask material 2 on the surface of the mask substrate 1, such as Figure 4 As shown in (a), the photolithography mask material 2 is a metal film layer or other film layer, and then a photoresist layer 3 is coated on the surface of the photolithography mask material 2. Figure 4 As shown in (b);
[0063] Step (32): using photolithography technology to transfer the predefined grating pattern onto the photoresist layer 3 and develop it to obtain a grating structure with a desired duty cycle: the grating period is 56 nm to 105 nm; the line width is 28 nm to 45 nm;
[0064] Step (33): Etching the grating structure obtained in step (32) to transfer the grating pattern structure in the photoresist layer 3 to the photolithography mask material 2, such as Figure 4 As shown in (c).
[0065] Step (4): Based on the simulation results of step (2), the mask pattern structure is filled with the appropriate filling medium in step (2) using advanced thin film deposition technology, so that the surface of the deposited filling medium 4 is higher than the surface of the pattern structure obtained in step (33), such as Figure 4 As shown in (d) above; equivalent to S4 above.
[0066] Step (5): annealing the entire mask obtained in step (4) or annealing a portion of its upper surface, such as Figure 4 As shown in (e), the cavity 5 in the optimal filling medium 4 is removed, the dielectric constant of the optimal filling medium is further adjusted, and its optical and mechanical properties are improved;
[0067] Step (6): The mask obtained in step (5) is flattened by ion beam etching or chemical mechanical polishing (CMP), such as Figure 4 As shown in (f), the surface of the optimal filling medium is flush with the surface of the mask pattern structure, and finally a contrast-optimized anti-pollution medium-filled mask is obtained; this is equivalent to the above S5.
[0068] According to the above steps (1) to (6), the following three embodiments are provided for illustration:
[0069] Embodiment 1:
[0070] The preparation method of the anti-pollution medium-filled mask with optimized contrast in this embodiment has the following specific implementation steps:
[0071] Step 1-1: Use COMSOL software to build a two-dimensional model of the SP lithography metalens, including the mask substrate (SiO 2 ), photolithography mask layer (Cr), air spacer layer (Air), metal transmission layer (Ag), photoresist layer (Pr), metal reflection layer (Ag) and substrate (Si), with corresponding thicknesses of 200 nm, 40 nm, 30 nm, 12 nm, 30 nm, 50 nm and 200 nm, respectively. The metal transmission layer (Ag) and photoresist layer (Pr) were scanned, and the scanning ranges were 8~36 nm and 18~46 nm, respectively. The key film layer parameters of the superlens were optimized according to the contrast hotspot map and the actual process parameter limitations.
[0072] Step 1-2: According to the optimized metalens key film layer parameters under different parameter mask conditions in step 1-1, the mask slit is simulated to be filled with media with different refractive indices (1~10). From the simulated contrast curve, it can be obtained that the refractive index of the filling medium higher than the baseline ranges from 1~6.2 (period 105 nm) to 1~5.4 (period 90 nm) and meets the actual process limitations and requirements such as the type of thin film deposition source material, acid and alkali resistance, high temperature and high mechanical properties. The suitable filling medium can be SiO 2 、Si 3 N 4 , HfO 2 、ZrO 2 、 2 O 5 , Nb 2 O 5 , WO 3 , AlAs, ZnS, TiN and TaN. This embodiment provides SiO 2 An actual filling example of . Figure 5 The cross-sectional view of the dielectric-filled mask before and after planarization according to the embodiment of the present disclosure is schematically shown. Figure 6 It shows that SiO 2 Comparison of the mask before and after filling and the corresponding exposure pattern, from Figure 6 It can be seen that the SiO 2 The contrast of the exposed pattern of the rear mask is better than that of the unfilled one, and Figure 5 The simulation results of and are consistent (corresponding to the horizontal coordinates 1.46 and 1, respectively), which confirms the performance of the dielectric-filled mask in improving resolution performance. On the other hand, since the slits of the mask grating are filled with dielectric, the anti-pollution performance of the mask is effectively improved, which increases the service life of the mask in SP lithography.
[0073] Step 1-3: A Cr film layer with a thickness of 40 nm is prepared on the surface of the mask substrate 1, and the photoresist layer 3 is electron beam gel ARP-6200 with a film thickness of 100 nm.
[0074] Step 1-4: Perform SP lithography on the photoresist layer 3, and write into the photoresist layer 3 grating patterns with predefined periods of 105 nm and 90 nm and corresponding line widths of 25 nm and 20 nm.
[0075] Step 1-5: Transfer the grating pattern to the photolithography mask material 2 by etching, wherein the etching method is RIE etching.
[0076] Step 1-6: Deposit the appropriate filling medium 4 (SiO 2 ) is deposited onto the surface of the etched photolithography mask material 2, and the surface of the filling medium 4 is higher than the surface of the graphic structure in the photolithography mask material 2.
[0077] Step 1-7: perform overall annealing treatment on the mask including the filling medium 4, with an annealing temperature of 200°C, an annealing time of 1 hour, a heating rate of 10°C / min, and a cooling rate of 20°C / min; to reduce defects such as cavities 5 in the filling medium 4.
[0078] Step 1-8: Use chemical mechanical polishing (CMP) to planarize the film layer so that the surface of the optimal filling medium 4 is flush with the surface of the photolithography mask material 2, and finally obtain a contrast-optimized anti-pollution medium filling mask, such as Figure 5 shown.
[0079] Embodiment 2:
[0080] The preparation method of the anti-pollution medium-filled mask with optimized contrast in this embodiment has the following specific implementation steps:
[0081] Step 2-1: Use FDTD software to establish a two-dimensional model of the SP lithography metalens, including the structures of the mask substrate (Si), lithography mask layer (Ta), air spacer layer (Air), metal transmission layer (Ag), photoresist layer (Pr), metal reflection layer (Ag) and substrate (Si), with corresponding thicknesses of 200 nm, 58 nm, 30 nm, 12 nm, 30 nm, 50 nm and 200 nm, respectively. Scan the metal transmission layer (Ag) and photoresist layer (Pr), with a scanning range of 8~36 nm and 18~46 nm, respectively. According to the contrast hotspot map and the actual process parameter limitations, the optimized key film layer parameters of the metalens are obtained.
[0082] Step 2-2: According to the optimized key film parameters of the metalens under different parameter mask conditions in step 2-1, the mask slit is simulated to be filled with media with different refractive indices (1~10). From the simulated contrast curve, it can be obtained that the refractive index of the filling medium higher than the baseline ranges from 1~5.2 (period 105 nm) to 1~3.7 (period 90 nm), and meets the actual process limitations and requirements such as the type of thin film deposition source material, acid and alkali resistance, high temperature and high mechanical properties. The suitable filling medium can be SiO 2 、Si 3 N 4 , HfO 2 、ZrO 2 、 2 O 5 , Nb 2 O 5 , WO 3 , AlAs, ZnS, TiN and TaN, etc.
[0083] Step 2-3: A Ta film layer with a thickness of 58 nm is prepared on the surface of the mask substrate 1, and the photoresist layer 3 is a PHS photoresist with a film thickness of 100 nm.
[0084] Step 2-4: Using electron beam exposure technology on the photoresist layer 3, write into the photoresist layer 3 a grating pattern with predefined periods of 105 nm and 90 nm and corresponding line widths of 25 nm and 20 nm.
[0085] Step 2-5: Transfer the grating pattern structure into the photolithography mask material 2 by etching, wherein the etching method is ICP etching.
[0086] Step 2-6: Deposit the filling medium 4 (ZnS) determined in step 1-2 onto the surface of the etched functional layer 2 by magnetron sputtering technology, wherein the surface of the filling medium 4 is higher than the surface of the graphic structure in the photolithography mask material 2 .
[0087] Step 2-7: Anneal the upper surface portion of the mask including the filling medium 4 at a temperature of 200°C, an annealing time of 1 hour, a heating rate of 10°C / min, and a cooling rate of 20°C / min to reduce defects such as cavities 5 in the filling medium 4.
[0088] Step 1-8: Planarize the film layer by etching process, so that the surface of the optimal filling medium 4 is flush with the surface of the photolithography mask material 2, and finally obtain a contrast-optimized anti-pollution medium filling mask.
[0089] Embodiment 3:
[0090] The preparation method of the anti-pollution medium-filled mask with optimized contrast in this embodiment has the following specific implementation steps:
[0091] Step 3-1: Use the RCWA algorithm to establish a two-dimensional model of the SP lithography metalens, including the structure of the mask substrate (sapphire), lithography mask layer (Mo), air spacer layer (Air), metal transmission layer (Ag), photoresist layer (Pr), metal reflection layer (Ag) and substrate (Si), with corresponding thicknesses of 200 nm, 40 nm, 30 nm, 12 nm, 30 nm, 50 nm, and 200 nm, respectively. The metal transmission layer (Ag) and photoresist layer (Pr) are scanned, with a scanning range of 8~36 nm and 18~46 nm, respectively. The optimized key film layer parameters of the metalens are obtained based on the contrast hotspot map and the actual process parameter limitations.
[0092] Step 3-2: According to the optimized parameters of the key film layer of the metalens under different parameter mask conditions in step 3-1, the mask slit is simulated to be filled with media with different refractive indices (1~10). From the simulated contrast curve, it can be obtained that the refractive index of the filling medium higher than the baseline ranges from 1~1.6, 3.5~4.3 and 7.0~7.6 (period 105 nm), 1~3.8 and 4.8~7.0 (period 90 nm), and it meets the actual process limitations and requirements such as the type of thin film deposition source material, acid and alkali resistance, high temperature and high mechanical properties. The suitable filling medium can be SiO 2 、ZrO 2 , TiN and TaN, etc.
[0093] Step 3-3: A Mo film layer with a thickness of 60 nm is prepared on the surface of the sapphire mask substrate 1, and the photoresist layer 3 is AR-P 3170 photoresist with a film thickness of 100 nm.
[0094] Step 3-4: Using projection lithography technology on the photoresist layer 3, write into the photoresist layer 3 a grating pattern with predefined periods of 105 nm and 90 nm and corresponding line widths of 25 nm and 20 nm.
[0095] Step 3-5: Transfer the grating pattern structure into the photolithography mask material 2 by etching, and the etching method is IBE etching.
[0096] Step 3-6: Deposit the optimal filling medium 4 (AlAs) determined in step 3-2 onto the surface of the etched photolithography mask material 2 by chemical vapor deposition technology, wherein the surface of the optimal filling medium 4 is higher than the surface of the graphic structure in the photolithography mask material 2 .
[0097] Step 3-7: perform overall annealing treatment on the mask including the filling medium 4, with an annealing temperature of 200°C, an annealing time of 1 hour, a heating rate of 10°C / min, and a cooling rate of 20°C / min; to reduce defects such as cavities 5 in the filling medium 4.
[0098] Step 3-8: Planarize the film layer by etching process, so that the surface of the filling medium 4 is flush with the surface of the photolithography mask material 2, and finally obtain a contrast-optimized anti-pollution medium filling mask.
[0099] The present disclosure provides a new solution to the technical problems such as insufficient contrast faced by the existing photolithography technology. In practical applications, the main technical effects that can be achieved include at least:
[0100] (1) Improving the anti-pollution properties of the mask: Using specific dielectric materials to fill the slits of the mask can effectively prevent contaminants from falling into the slits of the mask, thereby improving the contaminant tolerance of the mask;
[0101] (2) Improving lithography contrast: Filling the slits of the mask with specific dielectric materials can significantly enhance the contrast during the lithography process and suppress or reduce the blur and distortion of the exposed pattern.
[0102] (3) Obtaining high-resolution structures: Due to the improved contrast of lithography, the prepared structures are smaller and the resolution is significantly improved, meeting the needs of future high-precision processes;
[0103] (4) Simplified process flow: This contrast optimization method avoids the use of complex lithography equipment or special processing techniques. Instead, it achieves contrast improvement by changing the dielectric material, thereby simplifying the overall preparation process.
[0104] (5) Improve production efficiency: High-contrast lithography technology can shorten exposure time and subsequent processing steps, thereby improving overall production efficiency;
[0105] (6) Cost reduction: Due to the simplification of the process and the reduction of dependence on high-precision equipment, the production cost has been reduced to a certain extent.
[0106] 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 preparing a contrast-optimized anti-pollution dielectric-filled mask, characterized in that: include: S1, performing simulation calculation according to mask conditions to obtain optimized key film layer parameters of the superlens; S2, according to the optimized parameters of the key film layer of the superlens, the graphic structure of the mask is simulated and filled with different refractive index media and simulation is performed to obtain a contrast curve; S3, determining a contrast-optimized filling medium adapted to the actual working environment according to the contrast curve; S4, preparing a pattern structure of a mask according to the mask condition, and filling the pattern structure with the filling medium determined in S3; S5, annealing and planarization are performed on the mask obtained in S4 in sequence to obtain a contrast-optimized anti-pollution medium-filled mask.
2. The method for preparing a contrast-optimized anti-pollution dielectric-filled mask according to claim 1, characterized in that: The method for performing simulation calculation in S1 includes any one of rigorous coupled wave analysis, finite difference time domain method and finite element method.
3. The method for preparing a contrast-optimized anti-pollution dielectric-filled mask according to claim 1, characterized in that: The key film layer parameters of the super lens in S1 at least include the material and thickness of the metal transmission layer and the photoresist layer; The material of the metal transmission layer includes any one of Au, Ag, Al, and Cu; the material of the photoresist layer includes any one of AR series, AZ series, and PMMA series photosensitive materials.
4. The method for preparing a contrast-optimized anti-pollution dielectric-filled mask according to claim 1, characterized in that: The refractive index of the different refractive index media used for simulation in S2 is 1-10; The different refractive index media include several of SiO2, Si3N4, HfO2, TiO2, Al2O3, ZrO2, Ta2O5, Nb2O5, WO3, AlAs, ZnS, TiN and TaN.
5. The method for preparing a contrast-optimized anti-pollution dielectric-filled mask according to claim 1, characterized in that: The S3 includes: According to the contrast curve, a material having a higher contrast than the baseline without filling (and capable of adapting to the actual working environment) is determined as the filling medium.
6. The method for preparing a contrast-optimized anti-pollution dielectric-filled mask according to claim 1, characterized in that: The step of preparing the pattern structure of the mask plate according to the mask condition in S4 includes: Depositing a photolithography mask material on the substrate of the mask plate, and preparing pattern structures of different periods and line widths by photolithography and etching methods; Among them, the lithography method includes any one of surface plasma lithography, electron beam direct writing lithography, and projection lithography; the etching method includes any one of ion beam etching, reactive ion beam etching, inductively coupled plasma etching, and capacitively coupled high energy plasma etching.
7. The method for preparing a contrast-optimized anti-pollution dielectric-filled mask according to claim 6, characterized in that: The base material of the mask in S4 includes any one of sapphire, quartz, silicon, and magnesium fluoride; The photolithography mask material includes any one of Cr, Ta, and Mo.
8. The method for preparing a contrast-optimized anti-pollution dielectric-filled mask according to claim 1, characterized in that: The method of filling the filling medium determined in S3 in S4 includes any one of vacuum evaporation deposition, magnetron sputtering deposition, atomic layer deposition, and chemical vapor deposition, wherein the surface of the filling medium is higher than the surface of the graphic structure of the mask, and step effect is required to be avoided.
9. The method for preparing a contrast-optimized anti-pollution dielectric-filled mask according to claim 1, characterized in that: The annealing temperature in S5 is 100°C to 1000°C, the heating rate is 10°C to 100°C / min, the cooling rate is 10°C to 50°C / min, and the holding time is 0.5 to 10 hours; The planarization method in S5 includes any one of ion beam etching and chemical mechanical polishing, wherein the surface of the filling medium after the planarization is flush with the surface of the pattern structure of the mask.
10. A contrast-optimized anti-pollution dielectric-filled mask, characterized in that: The mask is prepared by the method for preparing a contrast-optimized anti-pollution medium-filled mask as described in any one of claims 1 to 9.