Method of manufacturing pellicle for 3㎚ EUV lithography

Abstract

The present invention relates to a method for manufacturing a pellicle for a 3 nm EUV lithography process, comprising: a silicon ingot growth step of growing a single-crystal silicon ingot from polysilicon to prepare a silicon ingot which is a pellicle material; and a frame processing step of processing the grown silicon ingot into a frame of the pellicle. According to the present method, an EUV lithography pellicle can be manufactured that has excellent durability and anti-contamination properties, thereby preventing wafer pattern defects during the process and ultimately improving the efficiency of the EUV lithography process.

Description

Technology Field

[0001] The present invention relates to a manufacturing technology for components used in semiconductor lithography processes, and specifically, to a manufacturing technology for EUV lithography pellicles used in 3 nm class semiconductor processes that have excellent durability and anti-contamination properties. Background Technology

[0002] EUV (Extreme Ultraviolet) pellicles are a key component used in the EUV lithography process during semiconductor manufacturing. As a thin film that protects the photomask, the pellicle performs the function of protecting the photomask.

[0003] The EUV lithography process is a process of etching very fine circuit patterns onto a wafer. A photomask is a plate on which these circuit patterns are etched, and if contaminated by dust or foreign substances, it can seriously affect the quality of the circuits. A pellicle is placed over the photomask to protect it from dust and foreign substances.

[0004] In addition, using a pellicle can prevent photomask contamination, thereby lowering the wafer defect rate and improving yield. Furthermore, since photomasks require cleaning when contaminated, using a pellicle reduces the frequency of cleaning, which can increase productivity.

[0005] EUV lithography is an essential technology for state-of-the-art semiconductor manufacturing, and pellicles are a core component of this process; as the miniaturization of the EUV process progresses, the importance of pellicles is growing even more.

[0006] Figure 1 is a photograph showing a typical pellicle film and pellicle frame.

[0007] In particular, 3nm EUV pellicles are used to improve yield in semiconductor processes by protecting expensive 3nm EUV masks, which cost up to 500 million won, and by suppressing pattern defects caused by contaminant particles generated during the process as described above.

[0008] The performance requirements for 3nm EUV pellicles vary depending on the output of the lithography machine. As EUV lithography machine output is expected to continuously increase to 600W by 2025, there is a need to develop new materials that surpass the durability of the currently mass-produced 400W-class EUV pellicle frames. While research on the 3nm EUV pellicle film itself is currently in the final stages of development, contamination issues caused by the EUV pellicle frame material have arisen in the 3nm lithography process, making research and development for improvement urgent. Conventional frame materials being studied include metals such as aluminum alloys, materials containing coating films, and carbon composite materials.

[0009] As the output of EUV lithography machines increases, the problem of contamination regarding EUV pellicle frame materials is accelerating, which is further accelerating the demand for changes in EUV pellicle frame materials. Prior art literature

[0010] Korean Published Patent No. 10-2024-0161625 (2024.11.12) (EUV pellicle frame and EUV pellicle using the same) The problem to be solved

[0011] The present invention is an invention sought in consideration of the development requirements for frame materials of EUV lithography pellicles as described above, and aims to provide a method for manufacturing an EUV lithography pellicle having excellent durability and anti-contamination properties. means of solving the problem

[0012] A method for manufacturing an EUV lithography pellicle according to one embodiment of the present invention is a method for manufacturing a pellicle for a 3 nm EUV lithography process, comprising: a silicon ingot growth step of growing a single-crystal silicon ingot from polysilicon to prepare a silicon ingot which is a pellicle material; and a frame processing step of processing the grown silicon ingot into a frame of the pellicle.

[0013] The above silicon ingot growth step can be carried out within a silicon ingot growth machine equipped with a motion control function for controlling the ingot growth speed.

[0014] The above silicon ingot growth equipment may have a dual vision camera module installed.

[0015] The above silicon ingot growth equipment may be equipped with a heater reinforced with insulation material at the top and bottom.

[0016] The above frame processing step may include: a pretreatment step of removing and trimming impurities from the surface of a silicon ingot; a step of preparing a wafer by slicing the silicon ingot; a first polishing step of polishing the surface of the wafer; an MCT processing step of processing the polished wafer into a pellicle frame shape; a step of etching the processed pellicle frame to remove impurities; and a second polishing step of polishing the surface of the pellicle frame from which impurities have been removed.

[0017] The above slicing can be performed by a wire on which diamond powder is electrodeposited onto a nerd wire.

[0018] The above first polishing step can be performed using an alkali-based slurry containing colloidal silica. Effects of the invention

[0019] According to the method for manufacturing a frame of an EUV lithography pellicle according to the present invention, it is made of low-resistance silicon (Si) having a purity equal to or greater than that of a wafer in the process, and thus it is possible to manufacture an EUV lithography pellicle that can effectively block contamination of the frame under a 3 nm-class EUV lithography process.

[0020] In addition, the pellicle frame manufactured by the above manufacturing method can maintain excellent durability even when using an exposure machine with an output of 600W or more, so that deformation of the frame due to stage acceleration does not occur.

[0021] Consequently, when using a pellicle manufactured by the above method, the efficiency of the EUV lithography process can be improved by minimizing process defects caused by particle generation on the wafer during the lithography process and suppressing the phenomenon of wafer pattern increase due to carbon contamination, etc.

[0022] Meanwhile, the above manufacturing method can maximize the purity and low resistance characteristics of the silicon ingot produced by uniformly controlling the growth rate during the growth process of the silicon ingot, which is the pellicle material, and minimizing the thermal gradient of the hot zone. Brief explanation of the drawing

[0023] Figure 1 is a photograph showing a typical pellicle film and pellicle frame. FIG. 2 is a graph showing the temperature rise characteristics and thermal expansion characteristics of silicon, which is a pellicle frame material according to one embodiment of the present invention. Figure 3 is a photograph showing contamination of EUV pellicles made of aluminum alloy, Si coating material, and carbon composite material, respectively, and an increase in the pattern of the exposure area due to this. Figure 4 is a drawing showing the problems during the growth of silicon ingots and the resulting damage during the pellicle frame processing process. Figure 5 is a diagram showing the problems in the conventional pellicle frame manufacturing process and technical points for solving them. FIG. 6 is a diagram conceptually showing all the processes of a method for manufacturing a pellicle frame according to one embodiment of the present invention. FIG. 7 is a graph showing a silicon ingot growth apparatus according to one embodiment of the present invention and a growth rate controlled through it. Figure 8 is an optical system diagram showing an outer diameter control method using a vision camera. Figure 9 is a diagram illustrating a simulation of a hot zone. Figure 10 is a drawing showing the insulation material reinforced for the heater of a silicon single crystal growth equipment. FIG. 11 is a drawing showing a comparison between a conventional wire cutting process and a cutting process of a diamond powder electrodeposited wire according to one embodiment of the present invention. Specific details for implementing the invention

[0024] Hereinafter, a method for manufacturing an EUV lithography pellicle according to an embodiment of the present invention will be described in detail with reference to the attached drawings. However, the following descriptions are exemplary descriptions intended to explain the embodied form of the technical concept of the present invention, and the technical concept of the present invention is not limited by the following descriptions. The technical concept of the present invention can only be interpreted and limited by the claims set forth below.

[0025] The frame of the EUV lithography pellicle according to the present invention is made of pure silicon, which is the same material as the wafer, so that it has a low coefficient of thermal expansion and can thereby achieve low resistance characteristics.

[0026] FIG. 2 is a graph showing the temperature rise characteristics and thermal expansion characteristics of silicon, which is a pellicle frame material according to one embodiment of the present invention. Referring to the graph on the right, it can be seen that the deformation of the frame made of silicon material is minimized.

[0027] Meanwhile, as a comparative example, contamination of the pellicle made of aluminum alloy, Si coating material, and carbon composite material occurs severely as shown in Fig. 3, and consequently acts as a factor that increases the pattern size of the exposure area.

[0028] Figure 3 is a photograph showing contamination of EUV pellicles made of aluminum alloy, Si coating material, and carbon composite material, respectively, and an increase in the pattern of the exposure area due to this.

[0029] In order to overcome this contamination phenomenon, the frame of the EUV lithography pellicle according to one embodiment of the present invention is processed to be made of pure silicon ingot.

[0030] In particular, the frame of the EUV lithography pellicle is made of low-resistance silicon having a resistivity of 0.1 to 0.8 Ω·cm. In addition, in terms of purity, the silicon frame has a purity of 6N or higher.

[0031] In addition, as the output of EUV lithography machines is expected to continuously increase to 600W by 2025, materials that surpass the durability of currently mass-produced 400W-class EUV pellicle frames are required, and the EUV lithography pellicle of the present invention can function smoothly without a decrease in durability even in such increased output environments.

[0032] Table 1 below shows the physical properties of silicon forming an EUV pellicle frame according to one embodiment of the present invention.

[0033] Physical properties Physical properties Resistivity (Ω·cm) 0.1 ~ 0.8 Purity (N) ≥ 7N Life time (μs) ≥ 10㎲

[0034] The above pellicle frame can be manufactured by processing a single-crystal silicon ingot grown from polysilicon.

[0035] Table 2 below shows the characteristics of an EUV pellicle frame according to one embodiment of the present invention.

[0036] characteristic characteristic value Frame thickness 1,500±10㎛ Frame thickness deviation ≤3 ㎛ Frame surface roughness ≤1.0 ㎚

[0037] The low-resistance silicon ingot used for manufacturing the above-mentioned pellicle frame has a low ingot growth yield due to an increase in the amount of dopant during ingot growth, and there are problems such as breakage during frame processing, so an ingot growth method and a method for manufacturing a pellicle frame using the ingot are required to overcome these issues. Figure 4 is a diagram showing the problems during silicon ingot growth and the resulting breakage problems during the pellicle frame processing process.

[0038] Below, a method for manufacturing the above-mentioned EUV lithography pellicle frame will be described.

[0039] The method for manufacturing a frame of an EUV lithography pellicle described above largely comprises the steps of growing a silicon ingot as a frame material and processing the grown silicon ingot into a frame shape. According to the present method, a high-purity, low-resistance silicon ingot can be grown, and deformation or damage to the frame of the manufactured pellicle can be effectively prevented during the lithography process.

[0040] Figure 5 is a diagram showing the problems in the conventional pellicle frame manufacturing process and technical points for solving them.

[0041] In order to solve the aforementioned problems, as shown in FIG. 5, the method for manufacturing the pellicle frame includes additional techniques for controlling silicon ingot growth, techniques for controlling saw damage, additional techniques for surface polishing, and additional techniques for an etching process.

[0042] Meanwhile, specifically, the method for manufacturing the above-mentioned pellicle frame includes various processes as shown in FIG. 6. FIG. 6 is a diagram conceptually showing all processes of the method for manufacturing a pellicle frame according to one embodiment of the present invention.

[0043] Referring to FIG. 6, a method for manufacturing a pellicle frame according to one embodiment of the present invention includes a silicon ingot growth step and a frame processing step. The frame processing step includes a pretreatment step (cropping, grinding) for trimming the surface of the ingot; a step of preparing a wafer by slicing the ingot; a first polishing step for polishing the surface of the wafer; an MCT processing step for processing the pellicle frame shape; a step of removing impurities by etching the processed frame; and a second polishing step for polishing the final processed frame.

[0044] In this embodiment, the silicon ingot growth step basically performs ingot growth by the Czochralski method (CZ), and a motion control function is applied to precisely control the ingot growth speed during the silicon ingot growth step. To this end, as shown in FIG. 7, the silicon ingot growth step is carried out within an ingot growth device equipped with a camera module. That is, by replacing the conventional servo motor, which is unable to control the growth speed precisely, precise ingot growth is enabled through the motion control function. FIG. 7 is a graph showing a silicon ingot growth device according to an embodiment of the present invention and the growth rate controlled therethrough. Meanwhile, FIG. 8 is an optical system diagram showing an outer diameter control method using a vision camera.

[0045] In particular, the present invention applies a dual camera system to collect and analyze process information from a vision system during the silicon ingot growth stage in order to manufacture a more uniform single-crystal ingot.

[0046] Meanwhile, the silicon ingot growth stage may include a hot zone optimization design stage in which the hot zone is optimized by performing heat transfer, fluid dynamics, and thermal stress analysis to achieve a uniform temperature distribution and minimize thermal gradients during silicon single crystal growth. Figure 9 is a diagram illustrating a simulation of the hot zone.

[0047] Based on simulation results, in order to achieve uniform temperature distribution and minimize thermal gradients during silicon single crystal growth, the present embodiment may use a silicon ingot growth apparatus with insulation reinforced on the upper and lower parts of the heater. FIG. 10 is a drawing showing the insulation reinforced on the heater of the silicon single crystal growth apparatus.

[0048] When a silicon ingot for processing a pellicle frame is prepared, a step of processing the pellicle frame with said silicon ingot is performed. To do this, a step of smoothing the surface of the silicon ingot is first performed. The smoothing process may include removing surface foreign substances and grinding.

[0049] Once the surface finishing step of the silicon ingot is completed, the step of slicing the silicon ingot to prepare a wafer is performed. In the conventional process of cutting silicon ingots, a wire mixed with SiC powder on a nud wire was mainly used; however, since cutting by the polishing action of the SiC powder requires a long processing time, in this embodiment, a wire with diamond powder electrodeposited on the nud wire is used. FIG. 11 is a diagram showing a comparison of a conventional wire cutting process and a cutting process of a diamond powder electrodeposited wire according to an embodiment of the present invention.

[0050] As described above, using wire electroplated with diamond powder can improve the Thickness Variation (TTV) of the cutting surface by enhancing cutting speed and straightness. However, when using wire electroplated with diamond, product damage may occur due to wire breakage if the wire experiences friction during cutting. Therefore, to compensate for this, it is desirable to ensure that the wire is supplied sequentially when unwinding and winding it from the bobbin to prevent friction.

[0051] Meanwhile, if the cutting impact is severe during the slicing process, it may cause product damage during the subsequent polishing stage. Therefore, in order to mitigate the cutting impact during the slicing stage of the present invention, various control processes for the cutting temperature, wire speed, coolant flow rate, etc. may be included.

[0052] When a silicon ingot is cut and a wafer is prepared, a first polishing step is performed to polish the surface of the wafer. Prior to the first polishing step, a lapping step may be performed to remove impurities and damaged layers from the wafer surface.

[0053] In this embodiment, in the first polishing step, an alkali-based slurry containing colloidal silica is used.

[0054] When the first polishing step is completed, an MCT processing step is performed to form the polished wafer into a pellicle frame. Once the pellicle frame is produced through the MCT processing step, an etching step to remove surface impurities from the pellicle frame and a second polishing step for final product polishing are performed sequentially.

[0055] Thus, an EUV pellicle frame according to one embodiment of the present invention can be manufactured.

Claims

Claim 1 A method for manufacturing a pellicle for an EUV lithography process used in a 3nm-class semiconductor process, comprising: a silicon ingot growth step of growing a single-crystal silicon ingot from polysilicon to prepare a silicon ingot that serves as a material for a pellicle frame, wherein the silicon ingot is grown to have a purity greater than or equal to that of a wafer used in the semiconductor process; and a frame processing step of processing the grown silicon ingot into a frame of the pellicle, wherein the silicon ingot growth step is performed within a silicon ingot growth equipment equipped with an outer diameter control via a dual vision camera module and a hot zone in which a uniform temperature distribution is formed and a thermal gradient is minimized by reinforcing the upper and lower parts of a heater with insulating material, in order to suppress yield reduction and damage occurring when achieving a purity of 7N or higher and a resistivity of 0.1 to 0.8 Ω·cm. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 A method for manufacturing an EUV lithography pellicle according to claim 1, wherein the frame processing step comprises: a pretreatment step of removing and trimming impurities from the surface of a silicon ingot; a step of preparing a wafer by slicing the silicon ingot; a first polishing step of polishing the surface of the wafer; an MCT processing step of processing the polished wafer into a pellicle frame shape; a step of etching the processed pellicle frame to remove impurities; and a second polishing step of polishing the surface of the pellicle frame from which impurities have been removed. Claim 6 A method for manufacturing an EUV lithography pellicle according to claim 5, characterized in that the slicing is performed by a wire having diamond powder electrodeposited on a nerd wire. Claim 7 A method for manufacturing an EUV lithography pellicle according to claim 5, characterized in that the first polishing step is performed using an alkali-based slurry containing colloidal silica.

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