Mask and preparation method thereof

Abstract

The invention provides a mask and a preparation method thereof, and relates to the technical field of semiconductor manufacturing and the technical field of photoetching, and the preparation method comprises the following steps: forming a mask absorption layer, a hard masking layer and a photoresist layer which are sequentially stacked on a substrate; performing exposure and development on the photoresist layer based on the mask pattern, and forming a target pattern in the photoresist layer; etching the hard masking layer by taking the photoresist layer on which the target pattern is formed as a masking layer, and transferring the target pattern to the hard masking layer; etching the mask absorption layer by taking the photoresist layer with the target pattern and the hard mask layer as a mask layer together, adjusting the flow ratio of different gases in the first etching gases in different etching stages, and etching and transferring the target pattern to the mask absorption layer; and removing residues on the mask absorption layer, and carrying out post-treatment to obtain the mask plate.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor manufacturing technologies, specifically to the field of lithography technologies, and particularly to a mask and a method for manufacturing the same. Background Art

[0002] In the field of semiconductor manufacturing technologies, surface plasmon polaritons (SP) super-resolution lithography technology has gradually become one of the important lithography means. It uses a negative refractive superlens to achieve nanoscale lithography resolution, and can achieve a lithography resolution far less than half a wavelength at a long wavelength. However, to ensure the smooth progress of this lithography process, the quality of a high-quality mask (or lithography mask) is crucial, which determines the accurate transfer of patterns. The manufacturing quality of the mask directly affects the performance and yield of the final product.

[0003] Since the lithography principle of super-resolution lithography technology is different from that of traditional lithography technology, it cannot directly apply traditional standard lithography masks and must develop and prepare lithography masks suitable for super-resolution lithography technology. Specifically, for super-resolution lithography masks, there are requirements such as a 1:1 ratio between the mask feature size and the lithography pattern size, a high flatness of the mask substrate, and a relatively thin absorption layer thickness to meet the lithography requirements such as a shallower optical focal depth. Among them, the etching uniformity and accuracy of the absorption layer film are crucial. However, the plasma etching process of the mask absorption layer, such as a chromium (Cr) thin film, faces several challenges, including etching rate control, etching uniformity, by-product elimination, and other problems. Summary of the Invention

[0004] In view of the above problems, the present disclosure provides a mask and a method for manufacturing the same, which are used to at least partially solve the above technical problems.

[0005] One aspect of an embodiment of the present disclosure provides a method for manufacturing a mask, including: forming a sequentially stacked mask absorption layer, a hard mask layer, and a photoresist layer on a substrate; exposing and developing the photoresist layer based on a mask layout to form a target pattern in the photoresist layer; using the photoresist layer with the target pattern formed thereon as a mask layer to etch the hard mask layer and transfer the target pattern to the hard mask layer; using the photoresist layer with the target pattern formed thereon and the hard mask layer together as a mask layer to etch the mask absorption layer, adjusting the flow ratio of different gases in a first etching gas in different etching stages, and etching and transferring the target pattern to the mask absorption layer; removing residues on the mask absorption layer and performing post-treatment to obtain the mask.

[0006] According to an embodiment of the present disclosure, an etch mask for etching a mask absorber layer is formed by using a photoresist layer and a hard mask layer having a target pattern. The flow rate ratios of different gases in the first etch gas at different etch stages are adjusted, including: etching the mask absorber layer using an inductively coupled plasma etching apparatus; adjusting the flow rate ratios of different gases in the first etch gas at the first etch stage to a first flow rate range so that the plasma is uniformly distributed in the etch chamber; adjusting the flow rate ratios of different gases in the first etch gas at the second etch stage to a second flow rate range to adjust the chemical reaction balance in the plasma; the first etch stage is earlier than the second etch stage, and the first flow rate range is different from the second flow rate range.

[0007] According to an embodiment of the present disclosure, it further includes: determining the etch stage between the start time of etching and the etch time accounting for 60%-70% of the total etch duration as the first etch stage; determining the etch stage between the etch time accounting for 60%-70% of the total etch duration and the end time of etching as the second etch stage; using a mixed gas of chlorine and oxygen as the first etch gas; adjusting the flow rate ratio of chlorine to oxygen to 3.2:1 to 5.3:1 in the first etch stage; adjusting the flow rate ratio of chlorine to oxygen to 1.5:1 to 2.8:1 in the second etch stage.

[0008] According to an embodiment of the present disclosure, it further includes: setting the radio frequency power of the upper electrode of the inductively coupled plasma etching apparatus to 800 W to 1500 W, the radio frequency power of the upper electrode to 12 W to 50 W, the etch chamber pressure to 5 mTorr to 20 mTorr, and the etch temperature to -30 °C to 80 °C.

[0009] According to an embodiment of the present disclosure, etching the hard mask layer using a photoresist layer having a target pattern as a mask includes: etching the hard mask layer using a reactive ion etching apparatus, wherein setting the radio frequency power of the reactive ion etching apparatus to 50 W to 200 W, the etch chamber pressure to 3 mTorr to 20 mTorr, using a mixed gas of argon, trifluoromethane, and carbon tetrafluoride as the second etch gas, setting the flow rate of argon to 5 mTorr to 15 mTorr, setting the flow rate of trifluoromethane to 2 mTorr to 20 mTorr, and setting the flow rate of carbon tetrafluoride to 5 mTorr to 20 mTorr.

[0010] According to an embodiment of the present disclosure, forming a mask absorber layer, a hard mask layer, and a photoresist layer stacked in sequence on a substrate includes: using one of chromium, silicon, a mixture of chromium and chromium monoxide, and a mixture of molybdenum and silicon as the mask absorber layer material to form a mask absorber layer on the substrate; using one of silicon dioxide, silicon nitride, and tantalum as the hard mask layer material to form a hard mask layer on the mask absorber layer; spin-coating an electron beam photoresist on the hard mask layer to form a photoresist layer.

[0011] According to an embodiment of the present disclosure, a mask absorption layer, a hard mask layer, and a photoresist layer are sequentially stacked on a substrate, and further include: forming a mask absorption layer with a thickness of 40 nm to 120 nm, forming a hard mask layer with a thickness of 8 nm to 20 nm, and forming a photoresist layer with a thickness of 60 nm to 140 nm.

[0012] According to an embodiment of the present disclosure, one of AR-P 6200, ZEP 520A, UV135, PMMA, AR-N7520, and HSQ is used as an electron beam photoresist.

[0013] According to an embodiment of the present disclosure, the mask absorption layer and the hard mask layer are deposited by physical vapor deposition or plasma-enhanced chemical vapor deposition.

[0014] Another aspect of the embodiments of the present disclosure provides a mask, which is prepared by using the mask preparation method of the present disclosure.

[0015] The mask and its preparation method provided by the present disclosure have at least the following technical effects:

[0016] By dynamically adjusting the gas flow rate, it is ensured that the distribution of the plasma in the etching chamber is more uniform, thereby improving the etching consistency of each part of the mask. This uniform etching effect is particularly crucial for the accurate transfer of complex patterns and can significantly improve the quality of the final product.

[0017] By adjusting the gas flow rate in a specific etching stage, the balance of chemical reactions in the plasma can be adjusted, effectively promoting the gasification of by-products generated during the etching process. This helps to promptly remove the by-products, reduce their accumulation on the surface of the mask, and thus avoid affecting the etching depth and pattern accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, the above content and other objects, features, and advantages of the present disclosure will become clearer. In the drawings:

[0019] Figure 1 Schematically shows a flowchart of a mask preparation method according to an embodiment of the present disclosure.

[0020] Figure 2 Schematically shows a process route diagram of preparing a Cr mask based on different process modulation etching processes and preparing a Cr mask based on continuous etching according to an embodiment of the present disclosure.

[0021] Figure 3 Schematically shows an etching result and an SP exposure result diagram of a mask after etching optimization with a 105 nm period and a 45 nm aperture according to Embodiment 1 of the present disclosure.

[0022] Figure 4 Schematically shows the etching result and SP exposure result diagrams of a mask plate optimized for etching with a 105 nm period and a 40 nm (4×4) aperture according to Embodiment 1 of the present disclosure.

[0023] Figure 5 Schematically shows the etching result and SP exposure result diagrams of a mask plate optimized for etching with a 117 nm period and a 45 nm aperture according to Embodiment 1 of the present disclosure.

[0024] Figure 6 Schematically shows the etching result and SP exposure result of a mask plate optimized for etching with a 130 nm period and a 45 nm aperture according to Embodiment 1 of the present disclosure.

[0025] Figure 7 Schematically shows the etching result and SP exposure result diagrams of a mask plate before optimization for etching with a 105 nm period and a 45 nm aperture according to Embodiment 1 of the present disclosure.

[0026] Figure 8 Schematically shows the etching result and SP exposure result diagrams of a mask plate before optimization for etching with a 105 nm period and a 40 nm (4×4) aperture according to Embodiment 1 of the present disclosure.

[0027] Figure 9 Schematically shows the etching result and SP exposure result diagrams of a mask plate before optimization for etching with a 117 nm period and a 45 nm aperture according to Embodiment 1 of the present disclosure.

[0028] Figure 10 Schematically shows the etching result and SP exposure result of a mask plate before optimization for etching with a 130 nm period and a 45 nm aperture according to Embodiment 1 of the present disclosure. Detailed implementation manners

[0029] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the following detailed description, for the sake of explanation, many specific details are set forth in order to provide a comprehensive understanding of the embodiments of the present disclosure. However, obviously, one or more embodiments can also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present disclosure.

[0030] In one example, the plasma etching technology adopts a continuous etching process, that is, fixed etching parameters are used during the etching process, which limits the flexibility of etching. Especially in the complex pattern transfer process, it is difficult for fixed etching parameters to meet the changing etching conditions, resulting in uneven etching patterns, thereby affecting the quality of the final mask plate and the accuracy of the lithography pattern.

[0031] In view of this, embodiments of the present disclosure provide a method for preparing a mask based on an optimized plasma etching process, which can optimize the etching effect by regulating the etching gas flow rate at different stages during the etching process. The purpose of this method is to dynamically adjust the etching parameters according to the real-time state during the etching process, achieve precise control of the etching rate and uniformity, and thereby improve the manufacturing accuracy of the mask.

[0032] Figure 1 A flowchart of a mask preparation method according to an embodiment of the present disclosure is schematically shown.

[0033] As Figure 1 shown, the mask preparation method of this embodiment may include operations S110 to S150.

[0034] In operation S110, a mask absorption layer, a hard mask layer, and a photoresist layer are sequentially formed on a substrate.

[0035] In operation S120, the photoresist layer is exposed and developed based on a mask layout to form a target pattern in the photoresist layer.

[0036] In operation S130, the hard mask layer is etched using the photoresist layer with the target pattern formed thereon as a mask layer to transfer the target pattern to the hard mask layer.

[0037] In operation S140, the mask absorption layer is etched using the photoresist layer and the hard mask layer with the target pattern formed thereon together as a mask layer, and the flow rate ratio of different gases in the first etching gas at different etching stages is adjusted to transfer the target pattern to the mask absorption layer by etching.

[0038] In operation S150, the residues on the mask absorption layer are removed, and the mask is obtained after post-treatment.

[0039] According to an embodiment of the present disclosure, after transferring the target pattern onto the hard mask layer, the photoresist layer is not removed, but retained together with the hard mask layer as a mask layer to etch the mask absorber layer. The hard mask layer is equivalent to a hard mask layer and can play a role in transferring high aspect ratios, that is, transferring the target pattern in the photoresist layer downward to the mask absorber layer. After the photoresist layer is exhausted, the hard mask layer will continue to be consumed to ensure the downward etching of the mask absorber layer. This etching method can improve the quality of the target pattern in the mask absorber layer. For example, it can optimize the uniformity of the target pattern feature size, optimize the steepness of the target pattern, optimize the line edge roughness of the mask pattern, and reduce the defects of the target pattern. If the photoresist layer is removed and only the hard mask layer is used for etching transfer, the aspect ratio of the pattern will be too small, resulting in increased lateral etching and scattering etching, which will affect the pattern size fidelity and edge quality. After the etching is completed, the residues such as the hard mask layer on the mask absorber layer are removed, and the mask plate can be obtained through post-processing.

[0040] In some embodiments, a substrate with high transmittance (e.g., 365 nm wavelength), high surface flatness, and high stability can be selected as the base, such as a quartz substrate and a sapphire substrate.

[0041] In some implementations, a mask absorber layer, a hard mask layer, and a photoresist layer are sequentially stacked on the substrate, including:

[0042] One of chromium (Cr), silicon (Si), a mixture of chromium and chromium monoxide (Cr / CrO), a mixture of molybdenum and silicon (Mo / Si), etc. is used as the mask absorber layer material to form the mask absorber layer on the substrate. That is, the material of the mask absorber layer is a thin film material with low transmittance, high surface flatness, and high stability. As an alternative, a thin film can be grown on the substrate to form the mask absorber layer.

[0043] One of silicon dioxide (SiO2), silicon nitride (Si3N4), tantalum (Ta), etc. is used as the hard mask layer material to form the hard mask layer on the mask absorber layer. As an alternative, a thin film can be grown on the substrate to form the hard mask layer.

[0044] An electron beam photoresist is spin-coated on the hard mask layer to form the photoresist layer.

[0045] Furthermore, physical vapor deposition (PBD) or plasma enhanced chemical vapor deposition (PECVD) can be used to deposit the mask absorber layer and the hard mask layer.

[0046] In some embodiments, a mask absorption layer, a hard mask layer, and a photoresist layer are sequentially stacked on a substrate, and may further include:

[0047] A mask absorption layer with a thickness of 40 nm to 120 nm is formed on the substrate, a hard mask layer with a thickness of 8 nm to 20 nm is formed on the mask absorption layer, and a photoresist layer with a thickness of 60 nm to 140 nm is formed on the hard mask layer.

[0048] Furthermore, one of AR-P 6200, ZEP 520A, UV135, PMMA, AR-N7520, and HSQ can be used as an electron beam photoresist.

[0049] In some embodiments, the substrate with the stacked mask absorption layer, hard mask layer, and photoresist layer formed on its surface can be moved to an electron beam lithography device, and a mask layout is imported for electron beam direct writing exposure. After the exposure is completed, development is carried out using a developer corresponding to the electron beam photoresist, so that the mask layout is transferred onto the photoresist layer.

[0050] In some embodiments, the target pattern of the photoresist layer can be transferred onto the hard mask layer by dry etching. Exemplarily, taking the photoresist layer with the target pattern as the hard mask layer and etching the hard mask layer may include:

[0051] The hard mask layer is etched using a reactive ion etching (RIE) device. Among them, the radio frequency power of the reactive ion etching device is set to 50 W to 200 W, the etching chamber pressure is set to 3 mTorr to 20 mTorr, a mixed gas of argon (Ar), trifluoromethane (CHF3), and carbon tetrafluoride (CF4) is used as the second etching gas, the flow rate of argon is set to 5 mTorr to 15 mTorr, the flow rate of trifluoromethane is set to 2 mTorr to 20 mTorr, and the flow rate of carbon tetrafluoride is set to 5 mTorr to 20 mTorr.

[0052] In some embodiments, through dry etching, the pattern of the photoresist layer is transferred onto the mask absorption layer. Exemplarily, taking the photoresist layer and the hard mask layer with the target pattern together as the mask layer to etch the mask absorption layer, and adjusting the flow rate ratio of different gases in the first etching gas at different etching stages may include:

[0053] An inductively coupled plasma (ICP) device is used to etch the mask absorption layer.

[0054] Adjust the flow rate ratio of different gases in the first etch gas of the first etch stage to the first flow rate range, so that the plasma is evenly distributed in the etch chamber.

[0055] Adjust the flow rate ratio of different gases in the first etch gas of the second etch stage to the second flow rate range to adjust the balance of chemical reactions in the plasma.

[0056] The first etch stage is earlier than the second etch stage, and the first flow rate range is different from the second flow rate range.

[0057] The regulation of ICP etching of small-sized patterns is very crucial, and it is necessary to precisely regulate various process parameters of the ICP etching equipment.

[0058] In some embodiments, when using the photoresist layer and the hard mask layer with the target pattern formed together as the mask layer to etch the mask absorber layer, it further includes:

[0059] Determine the etch stage from the start of etching to the etch moment accounting for 60% - 70% of the total etch duration as the first etch stage. Determine the etch stage from the etch moment accounting for 60% - 70% of the total etch duration to the end of etching as the second etch stage.

[0060] A mixed gas of chlorine and oxygen can be used as the first etch gas.

[0061] For plasma etching using a Cl2 / O2 mixed gas, the etching principle equation for the Cr thin film is as follows:

[0062]

[0063]

[0064] As the etching process progresses continuously, the structure of the mask pattern also changes accordingly. For example, the consumption of the photoresist causes changes in the reaction balance, changes in the aspect ratio of the pattern, local accumulation of the plasma, and so on.

[0065] Based on this, in view of the changes in the pattern structure during different etching processes, adjust the etching parameters in different etching stages. In the first etch stage, adjust the flow rate ratio of chlorine and oxygen to 3.2:1 - 5.3:1. When the etching process reaches 60% - 70% of the total etching time (there are differences for different types of patterns), the photoresist is basically depleted. At this time, the consumption of O2 decreases, and the actual etch gas ratio changes. In the second etch stage (the last 30% - 40%), adjust the flow rate ratio of chlorine and oxygen to 1.5:1 - 2.8:1 to optimize the accumulation of by-products and improve the quality of the mask.

[0066] It should be noted that in the same etching stage, the flow ratio of chlorine and oxygen remains unchanged. For example, the flow ratio can be maintained at 3.2:1 throughout the first etching stage, and the flow ratio can be maintained at 1.5:1 throughout the second etching stage. Further, the upper electrode RF power of the inductively coupled plasma etching equipment can be set to 800 W~1500 W, the upper electrode RF power can be set to 12 W~50 W, the etching chamber pressure can be set to 5 mTorr~20 mTorr, and the etching temperature can be set to -30 ℃~80 ℃.

[0067] Finally, according to different processing requirements, after confirming that the processing quality in the above steps is correct, the steps of post-stripping cleaning, overlaying of focus inspection windows, focus inspection layer deposition, and final cleaning are carried out. SP exposure process is carried out to verify the correction effect of the mask.

[0068] The embodiment of the present disclosure further provides a mask, comprising:

[0069] A substrate and a mask absorption layer sequentially stacked on the surface of the substrate, wherein a target pattern is formed in the mask absorption layer. The mask is prepared by the preparation method provided in the embodiment of the present disclosure.

[0070] According to the embodiments of the present disclosure, the etching parameters are dynamically adjusted according to the changes in the graphic structure during the etching process, the etching reaction balance is optimized, and the uniformity of the etched graphics is improved, and the graphics with feature sizes of 40 nm and above have obvious improvement effects. This solution is mainly used in super-resolution lithography process systems, but is not limited to this, and can also be applied to near-contact exposure processes of other structures.

[0071] In order to further demonstrate the feasibility and advantages of the mask and the preparation method thereof provided by the embodiments of the present disclosure, some specific embodiments and comparative examples are described below in conjunction with the accompanying drawings.

[0072] Figure 2 The schematic diagram of the process route of preparing a Cr mask based on different process modulation etching processes and preparing a Cr mask based on continuous etching according to an embodiment of the present disclosure is schematically shown.

[0073] Example 1

[0074] like Figure 2 As shown, in this embodiment, the steps of preparing a Cr mask based on different process modulation etching processes and performing SP exposure based on the Cr mask can be as follows:

[0075] Step 1: Select a substrate with high transparency and high stability. Here, you can choose a quartz substrate or a sapphire substrate.

[0076] Step 2: The material of the mask absorption layer is selected as Cr. The mask absorption layer is grown on the substrate by chemical vapor deposition. The growth method is ion beam sputtering deposition process. The growth process is carried out at room temperature, and finally a 40 nm Cr thin film is obtained.

[0077] Step 3: Deposit a hard mask layer on the surface of the mask absorption layer. Thin films such as SiO2, Si3N4, Ta, etc. can be selected. The growth method of the hard mask layer can adopt PVD or PECVD deposition process, and the thickness is 8 nm - 20 nm.

[0078] Step 4: After confirming the quality of the mask absorption layer, spin-coat an electron beam photoresist on the surface of the hard mask layer to form a photoresist layer. The electron beam photoresist is AR-P 6200, and the thickness of the photoresist layer is 90 nm. Subsequently, pre-bake the photoresist layer at a temperature of 130 °C.

[0079] Step 5: Then move the mask plate to the electron beam lithography equipment, import the mask layout, and perform electron beam direct writing exposure. After the exposure is completed, develop, fix and post-bake the sample to form the target pattern in the photoresist layer.

[0080] Step 6: Through the dry etching process, transfer the target pattern in the photoresist layer to the hard mask layer. In this disclosure, an RIE etching equipment is used for etching the hard mask layer. The process parameters include radio frequency power (200 W), etching chamber pressure (8 mTorr), gas flow rate (Ar: 10 mTorr; CHF3: 2 mTorr; CF4: 6 mTorr).

[0081] After the post-bake is completed, move the mask plate to the etching equipment for dry etching. The ICP etching equipment is selected for dry etching. The upper electrode power is set to 1200 W, the lower electrode power is set to 40 W, and the etching chamber pressure is set to 15 mTorr. The etching process is divided into two stages. In the first 60% of the etching time, the Cl2 / O2 gas flow ratio is 3.2:1, and in the last 40% of the etching time, the Cl2 / O2 gas flow ratio is 1.5:1. According to the actual gas ratio change during the etching process, dynamically and precisely adjust the gas ratio in the front and back stages of etching to avoid the generation of non-gaseous etching by-products such as Cr2O3 during the late stage of etching, which accumulate on the sidewalls of the pattern and affect the mask quality. After the etching is completed, perform post-treatments such as removing the residual glue and cleaning the mask plate to complete the preparation of the mask plate.

[0082] Step 8: Use SEM to observe the processing situation of the mask plate, and use this mask plate for SP exposure process, and observe the mask pattern and exposure results through SEM. Among them, Figure 3Schematically shows the etching results and SP exposure results of the mask plate optimized for etching with a 105 nm period and a 45 nm aperture according to Embodiment 1 of the present disclosure. Figure 4 Schematically shows the etching results and SP exposure results of the mask plate optimized for etching with a 105 nm period and a 40 nm (4×4) aperture according to Embodiment 1 of the present disclosure. Figure 5 Schematically shows the etching results and SP exposure results of the mask plate optimized for etching with an 117 nm period and a 45 nm aperture according to Embodiment 1 of the present disclosure. Figure 6 Schematically shows the etching results and SP exposure results of the mask plate optimized for etching with a 130 nm period and a 45 nm aperture according to Embodiment 1 of the present disclosure.

[0083] Comparative Example 1

[0084] As Figure 2 shown, Comparative Example 1 is different from Step 7 in Embodiment 1, and the remaining steps are the same as those in Embodiment 1, and the experimental parameters of each step are the same, which will not be elaborated here.

[0085] Step 7: After the post-baking is completed, move the mask plate to the etching equipment for dry etching. The ICP etching equipment is selected for dry etching. The upper electrode power is set to 1200 W, the lower electrode power is set to 40 W, the etching chamber pressure is set to 15 mTorr, and continuous etching is carried out. Control the Cl2 / O2 gas flow ratio to be 3.2:1. After the etching is completed, perform post-treatments such as removing the residual glue and cleaning the mask plate to complete the preparation of the mask plate.

[0086] Step 8: Use SEM to observe the processing situation of the mask plate, and use this mask plate for the SP exposure process, and observe the mask pattern and exposure results through SEM. Among them, Figure 7 Schematically shows the etching results and SP exposure results of the mask plate before etching optimization with a 105 nm period and a 45 nm aperture according to Embodiment 1 of the present disclosure. Figure 8 Schematically shows the etching results and SP exposure results of the mask plate before etching optimization with a 105 nm period and a 40 nm (4×4) aperture according to Embodiment 1 of the present disclosure. Figure 9 Schematically shows the etching results and SP exposure results of the mask plate before etching optimization with an 117 nm period and a 45 nm aperture according to Embodiment 1 of the present disclosure. Figure 10 Schematically shows the etching results and SP exposure results of the mask plate before etching optimization with a 130 nm period and a 45 nm aperture according to Embodiment 1 of the present disclosure.

[0087] Compare Figure 3 with Figure 7 、 Figure 4 with Figure 8 、Figure 5 With Figure 9 and Figure 6 with Figure 10 , it can be seen that, compared with the results in the comparative example, the mask pattern in Example 1 presents a structural feature of uniform aperture, and the etch by-products attached around the pattern are also significantly reduced, indicating that the modulated etching can effectively adjust the reaction equilibrium of etching, keep the reaction rates in different regions stable, and effectively remove the etch by-products. In addition, it can be seen from the SP exposure results that the pattern size uniformity after modulated etching is better, while the pattern in Comparative Example 1 has poor mask uniformity, resulting in unsatisfactory pattern size uniformity of the exposed pattern. In summary, modulated etching is an effective solution to improve the uniformity of mask etching patterns.

[0088] The above describes the embodiments of the present disclosure. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although the embodiments are described separately above, this does not mean that the measures in each embodiment cannot be used in combination advantageously. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art can make various substitutions and modifications, and these substitutions and modifications should fall within the scope of the present disclosure.

Claims

1. A method for manufacturing a mask, characterized in that, Including: Forming a mask absorption layer, a hard mask layer, and a photoresist layer that are sequentially stacked on a substrate; Exposing and developing the photoresist layer based on a mask layout to form a target pattern in the photoresist layer; Using the photoresist layer with the formed target pattern as a mask layer to etch the hard mask layer and transfer the target pattern to the hard mask layer; Using the photoresist layer with the formed target pattern and the hard mask layer together as a mask layer to etch the mask absorption layer, adjusting the flow rate ratio of different gases in the first etching gas at different etching stages, and etching and transferring the target pattern to the mask absorption layer; Removing residues on the mask absorption layer, and obtaining a mask plate after post-treatment.

2. The method according to claim 1, wherein The step of using the photoresist layer with the formed target pattern and the hard mask layer together as a mask layer to etch the mask absorption layer, and adjusting the flow rate ratio of different gases in the first etching gas at different etching stages includes: Etching the mask absorption layer using an inductively coupled plasma etching device; Adjusting the flow rate ratio of different gases in the first etching gas in the first etching stage to a first flow rate range to make the plasma uniformly distributed in the etching chamber; Adjusting the flow rate ratio of different gases in the first etching gas in the second etching stage to a second flow rate range to adjust the balance of chemical reactions in the plasma; The first etching stage is earlier than the second etching stage, and the first flow rate range is different from the second flow rate range.

3. The method according to claim 2, wherein Further including: Determining the etching stage between the start time of etching and the etching time accounting for 60% - 70% of the total etching duration as the first etching stage; Determining the etching stage between the etching time accounting for 60% - 70% of the total etching duration and the end time of etching as the second etching stage; Wherein, a mixed gas of chlorine gas and oxygen gas is used as the first etching gas; In the first etching stage, adjusting the flow rate ratio of the chlorine gas and the oxygen gas to 3.2:1 - 5.3:1; In the second etching stage, adjusting the flow rate ratio of the chlorine gas and the oxygen gas to 1.5:1 - 2.8:

1.

4. The method according to claim 3, characterized in that, Further including: Setting the radio frequency power of the upper electrode of the inductively coupled plasma etching device to 800 W - 1500 W, the radio frequency power of the upper electrode to 12 W - 50 W, the etching chamber pressure to 5 mTorr - 20 mTorr, and the etching temperature to -30 °C - 80 °C.

5. The method according to any one of claims 1 to 4, characterized in that The step of using the photoresist layer with the formed target pattern as a mask layer to etch the hard mask layer includes: Etching the hard mask layer using a reactive ion etching device, wherein setting the radio frequency power of the reactive ion etching device to 50 W - 200 W, the etching chamber pressure to 3 mTorr - 20 mTorr, using a mixed gas of argon gas, trifluoromethane, and carbon tetrafluoride as the second etching gas, setting the flow rate of argon gas to 5 mTorr - 15 mTorr, setting the flow rate of trifluoromethane to 2 mTorr - 20 mTorr, and setting the flow rate of carbon tetrafluoride to 5 mTorr - 20 mTorr.

6. The method according to any one of claims 1 to 4, characterized in that Form a mask absorption layer, a hard mask layer, and a photoresist layer that are sequentially stacked on a substrate, including: Use one of chromium, silicon, a mixture of chromium and chromium monoxide, and a mixture of molybdenum and silicon as the mask absorption layer material, and form the mask absorption layer on the substrate; Use one of silicon dioxide, silicon nitride, and tantalum as the hard mask layer material, and form the hard mask layer on the mask absorption layer; Spin-coat an electron beam photoresist on the hard mask layer to form the photoresist layer.

7. The method according to claim 6, characterized in that, Form a mask absorption layer, a hard mask layer, and a photoresist layer that are sequentially stacked on a substrate, further including: Form a mask absorption layer with a thickness of 40 nm to 120 nm, form a hard mask layer with a thickness of 8 nm to 20 nm, and form a photoresist layer with a thickness of 60 nm to 140 nm.

8. The method according to claim 6, wherein Use one of AR-P 6200, ZEP 520A, UV135, PMMA, AR-N7520, and HSQ as the electron beam photoresist.

9. The method according to claim 6, wherein The mask absorption layer and the hard mask layer are formed by physical vapor deposition or plasma-enhanced chemical vapor deposition.

10. A mask, characterized in that, The mask template is prepared by the preparation method described in any one of claims 1 to 9.

Images