Extreme ultraviolet photoresist as well as preparation method and application thereof

Abstract

The invention discloses extreme ultraviolet photoresist as well as a preparation method and application thereof, and relates to the technical field of semiconductor processes. The extreme ultraviolet photoresist is a tellurium-based organic compound film and is prepared from an organic compound precursor of tellurium and an organic ligand through a molecular layer deposition method. Compared with a traditional photoresist preparation method adopting liquid-phase spin coating, the preparation method provided by the invention has the advantages of less material consumption and high process automation degree, and not only avoids the excessive use of an organic solvent, but also avoids the pollution of the traditional photoresist to expensive equipment. Meanwhile, the extreme ultraviolet photoresist with high sensitivity is successfully developed based on the tellurium-based organic compound film and is patterned, and the applicability of the tellurium-based organic compound film in the field of extreme ultraviolet lithography is proved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor process technology, and in particular to an extreme ultraviolet photoresist, its preparation method, and its application. Background Technology

[0002] With technological advancements, the demand for microelectronic devices in fields such as smartphones, high-performance computing, artificial intelligence, and the Internet of Things is constantly increasing. To achieve higher integration and smaller dimensions, manufacturing processes need to shift towards shorter wavelength lithography technologies. Extreme ultraviolet (EUV) lithography has emerged as a crucial means to overcome size limitations. EUV lithography utilizes an extreme ultraviolet light source (wavelength approximately 13.5nm) for pattern etching, offering significantly higher resolution than traditional deep ultraviolet (DUV) technology. This allows for smaller feature sizes to be achieved on the same silicon wafer, thereby improving chip performance and functionality. Photoresist is a key material for pattern conversion and the fabrication of fine structures; it is a core material in semiconductor technology, and its advanced technical specifications determine the sophistication of semiconductor devices and chips.

[0003] Despite its development, traditional photoresists still face numerous challenges in advanced extreme ultraviolet (EUV) lithography applications. Firstly, the main components (C, H, O) of traditional photoresists have low absorption under EUV irradiation. Obtaining high-resolution patterns requires increased power or extended exposure time and dosage, leading to drastically increased costs. Secondly, the large molecular size, entanglement, and uneven component distribution of polymer photoresists increase the roughness of the line edges after development. Furthermore, the organic solvents used to disperse the main components in traditional photoresists remain in large quantities after drying. These residual organic solvents evaporate after irradiation, potentially causing carbon contamination on the surface of optical components. Therefore, it is necessary to develop novel photoresists to match advanced EUV lithography technology and further advance advanced semiconductor processes. Summary of the Invention

[0004] This invention aims to address the shortcomings of traditional photoresists in extreme ultraviolet (EUV) lithography, providing an EUV photoresist, its preparation method, and its applications. This photoresist features a high absorption coefficient and is a non-chemically amplified tellurium-based organic compound thin-film photoresist, which can improve EUV light sensitivity and reduce line edge roughness. Furthermore, its dry coating process fundamentally eliminates the use of organic solvents, avoiding contamination of optical components.

[0005] Therefore, in a first aspect, the present invention provides an extreme ultraviolet (EUV) photoresist, wherein the EUV photoresist is a tellurium-based organic compound thin film, prepared by a molecular layer deposition method from an organic tellurium precursor and an organic ligand.

[0006] Furthermore, the thickness of the extreme ultraviolet photoresist is 5nm~50nm.

[0007] Furthermore, the amounts of the organic compound precursor of tellurium and the organic ligand are 1:1 to 1:4 in terms of the molar ratio of tellurium to the organic ligand.

[0008] Furthermore, the organic compound precursor of the tellurium is selected from one or more of ethanol tellurium, di(triethylsilyl) tellurium, di-tert-butyl tellurium, diethyl tellurium, and diisopropyl tellurium.

[0009] Furthermore, the organic ligand is selected from one or more of diols, dicarboxylic acids, dithiols, and diamines.

[0010] A second aspect of the present invention provides a method for preparing an extreme ultraviolet (EUV) photoresist, wherein the method comprises growing a tellurium-based organic compound thin film using a molecular layer deposition method, and includes the following steps: The first step is the pulsed generation of the organic compound precursor of tellurium: the organic compound precursor of tellurium is pulsed into the deposition chamber in the form of vapor, causing it to undergo chemical adsorption on the substrate surface; The second step is inert gas purging: inert gas is introduced to purge the deposition chamber and remove the unreacted organic compound precursor of the tellurium. The third step, the organic ligand pulse: the organic ligand is pulsed into the deposition chamber in the form of vapor, so that it reacts with the organic compound precursor of tellurium adsorbed on the substrate surface to form tellurium-based organic compounds; Fourth step, inert gas purging again: Inert gas is introduced again to purge the deposition chamber and remove unreacted organic ligand vapors and byproducts; Repeat steps one through four to obtain the tellurium-based organic compound film.

[0011] Furthermore, the molecular layer deposition temperature is 80℃~230℃, the molecular layer deposition time is 0.5h~8h, and the vacuum degree of molecular layer deposition is 0.1mbar~10mbar.

[0012] Furthermore, the single pulse duration of the tellurium organic compound precursor is 0.02s to 2s, the single pulse duration of the organic ligand is 0.05s to 5s, and the number of cycles is 30 to 300.

[0013] Furthermore, the preparation method further includes: Substrate pretreatment involves cleaning the substrate to remove surface contaminants and enrich its surface with hydroxyl groups; or, Substrate pretreatment involves cleaning the substrate to remove surface contaminants and enrich its surface with hydroxyl groups, followed by modification of the substrate using a silane coupling agent to enhance adhesion.

[0014] A third aspect of the present invention provides an application of an extreme ultraviolet (EUV) photoresist, which is used to form photolithographic patterns in an extreme ultraviolet (EUV) lithography process.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: The method for preparing extreme ultraviolet (EUV) photoresist provided by this invention has advantages over traditional liquid-phase spin-coating methods, including lower material consumption and higher automation. It not only eliminates the excessive use of organic solvents but also avoids the contamination of expensive equipment caused by traditional photoresists. Furthermore, based on tellurium-based organic compound thin films, a highly sensitive EUV photoresist was obtained and patterned, demonstrating the applicability of tellurium-based organic compound thin films in the field of EUV lithography. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in the embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0017] Figure 1 This is a photograph of vapor-coated photoresist provided in Embodiment 1 of the present invention.

[0018] Figure 2 The pattern obtained after photolithography and development is provided in Embodiment 1 of the present invention. Detailed Implementation

[0019] To better understand the above technical solutions, the technical solutions of the embodiments of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of this application and the specific features in the embodiments are detailed descriptions of the technical solutions of the embodiments of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0020] In a first aspect, an extreme ultraviolet (EUV) photoresist is provided, which is a tellurium-based organic compound thin film prepared by a molecular layer deposition method from an organic tellurium precursor and an organic ligand.

[0021] The extreme ultraviolet (EUV) photoresist provided in this invention can improve EUV light sensitivity, eliminate contamination of optical components, and reduce line edge roughness. It is a tellurium-based organic compound thin-film photoresist with a high absorption coefficient. Tellurium-based organic compound thin films offer significant advantages as EUV photoresists: firstly, tellurium has a high absorption coefficient for EUV light; secondly, the presence of organic matter makes it easier for chemical bonds or structural changes to occur under EUV irradiation, leading to differences in solubility and the formation of patterns.

[0022] In some embodiments, the thickness of the extreme ultraviolet photoresist is 5 nm to 50 nm.

[0023] Specifically, the thickness of extreme ultraviolet (EUV) photoresist is 5nm to 50nm. At this thickness, EUV photoresist possesses sufficient mechanical stability to effectively suppress pattern collapse after development and etching, ensuring higher resolution and finer line patterns. If the photoresist thickness reaches hundreds of nanometers or micrometers, collapse can easily occur when the etched lines are very fine.

[0024] In some embodiments, the amount of tellurium organic compound precursor and organic ligand used, in terms of the molar ratio of tellurium to organic ligand, is 1:1 to 1:4, preferably 1:1.

[0025] Specifically, as an element with a high extreme ultraviolet light absorption coefficient, increasing its content can absorb more extreme ultraviolet light, thereby generating more photoelectrons. More photoelectrons trigger more chemical bonds and structural changes, reducing random noise, reducing line edge roughness, and obtaining finer patterns.

[0026] In some embodiments, the organic compound precursor of tellurium is selected from one or more of ethanol tellurium, di(triethylsilyl) tellurium, di-tert-butyl tellurium, diethyl tellurium, and diisopropyl tellurium.

[0027] Specifically, the aforementioned tellurium organic compound precursors are characterized by high volatility, high saturated vapor pressure, and strong reactivity, which are conducive to the molecular layer deposition reaction.

[0028] In some embodiments, the organic ligand is selected from one or more of diols, dicarboxylic acids, dithiols, and diamines.

[0029] Specifically, diols such as ethylene glycol and 2,4-hexadiyne-1,6-diol; dicarboxylic acids such as oxalic acid, succinic acid, and octanoic acid; dithiols such as 1,2-ethylenedithiol; and diamines such as ethylenediamine and 1,6-hexanediamine.

[0030] A second aspect of this invention provides a method for preparing extreme ultraviolet (EUV) photoresist. The method involves growing a tellurium-based organic compound thin film using a molecular layer deposition method, and includes the following steps: The first step, tellurium organic compound precursor pulse: tellurium organic compound precursor is pulsed into the deposition chamber in vapor form, causing it to undergo chemical adsorption on the substrate surface; The second step is inert gas purging: inert gas is introduced to purge the deposition chamber and remove unreacted tellurium organic compound precursors. The third step is organic ligand pulse: organic ligands are pulsed into the deposition chamber in the form of vapor, so that they react with the tellurium organic compound precursor adsorbed on the substrate surface to form tellurium-based organic compounds. The fourth step is to purge the deposition chamber with inert gas again to remove unreacted organic ligand vapors and byproducts. Repeat steps one through four to obtain a tellurium-based organic compound film.

[0031] The extreme ultraviolet photoresist preparation method provided in this invention is a dry preparation method that does not involve liquid phase spin coating. By placing the target substrate in the reaction chamber of a molecular layer deposition device, based on the principle of self-limiting surface reaction, the vapor of tellurium-based organic compound precursor and the vapor of organic ligand are alternately pulsed and cyclically introduced. Inert gas is introduced between each pulse step to purge residual gas, thereby realizing the layer-by-layer growth of tellurium-based organic compound thin film and thus completing the dry coating of tellurium-based organic compound thin film.

[0032] In some embodiments, the molecular layer deposition temperature is 80°C to 230°C, the molecular layer deposition time (i.e., the total time of the gas phase reaction) is 0.5h to 8h, and the vacuum degree of molecular layer deposition is 0.1mbar to 10mbar.

[0033] Specifically, temperatures below 80°C result in low reaction rates or no reaction at all; temperatures above 230°C show little increase in reaction rate. The molecular layer deposition time, i.e., the total gas-phase reaction time, is 0.5 h to 8 h, and the vacuum level of the molecular layer deposition chamber is 0.1 mbar to 10 mbar.

[0034] In some embodiments, the single pulse duration of the tellurium organic compound precursor is 0.02 s to 2 s, the single pulse duration of the organic ligand is 0.05 s to 5 s, and the number of cycles is 30 to 300.

[0035] Understandably, the duration of the reactant pulse duration affects the film's microstructure (nucleation size and surface morphology). Shorter pulse durations result in smaller nucleation sizes and lower surface roughness. Controlling the single pulse duration of the tellurium organic compound precursor to 0.02 s–2 s and the single pulse duration of the organic ligand to 0.05 s–5 s is beneficial for obtaining films with small nucleation sizes, low surface roughness, and a dense, smooth surface. The number of cycles affects the film thickness; controlling the number of cycles to 30–300 yields films with thicknesses of 5 nm–50 nm.

[0036] In some embodiments, the preparation method further includes: Substrate pretreatment involves cleaning the substrate to remove surface contaminants and enrich its surface with hydroxyl groups; or, Substrate pretreatment involves cleaning the substrate to remove surface contaminants and enrich its surface with hydroxyl groups, followed by modification of the substrate using a silane coupling agent to enhance adhesion.

[0037] Specifically, substrate pretreatment effectively cleans the substrate surface and provides abundant reaction sites. In particular, the introduction of silane coupling agent significantly enhances the interfacial bonding between the tellurium-based organic compound film and the substrate. Optionally, the silane coupling agent is 7-octenyltrichlorosilane.

[0038] A third aspect of the present invention provides an application of extreme ultraviolet (EUV) photoresist, which is used to form photolithographic patterns in an extreme ultraviolet (EUV) lithography process.

[0039] The application of extreme ultraviolet (EUV) photoresist provided in this invention successfully combines the high absorption characteristics of tellurium-based materials with the process advantages of molecular layer deposition, exhibiting comprehensive performance of high resolution, low line edge roughness, and excellent pattern fidelity in EUV lithography.

[0040] Example 1: An extreme ultraviolet photoresist, its preparation method, and its application. (a) Extreme ultraviolet photoresist The extreme ultraviolet photoresist in Example 1 is a tellurium-based organic compound film with a thickness of 20 nm. It is prepared by molecular layer deposition of the tellurium organic compound precursor ethanol tellurium and the organic ligand ethylene glycol; wherein the molar ratio of tellurium to ethylene glycol is 1:1.

[0041] (II) Preparation method Includes the following steps: The first step is substrate pretreatment: First, the substrate is cleaned to remove surface contaminants and form hydroxyl groups on the surface. Then, the cleaned substrate is placed in the molecular layer deposition chamber. The chamber environment is controlled at a temperature of 85°C and a vacuum of 0.1 mbar in preparation for thin film deposition.

[0042] The second step is the pulsed generation of the organic compound precursor of tellurium: ethanol tellurium is pulsed into the deposition chamber in the form of vapor, and the duration of each pulse is controlled to be 1 second, so that a film is formed on the substrate surface.

[0043] The third step is inert gas purging: nitrogen gas is introduced to purge the deposition chamber and remove unreacted ethanol tellurium.

[0044] The fourth step is the organic ligand pulse: Ethylene glycol is pulsed into the deposition chamber in the form of vapor, and the duration of each pulse is controlled to be 1 second. The ethylene glycol reacts with the ethanol tellurium adsorbed on the substrate surface to form tellurium-based organic compounds.

[0045] Fifth step, inert gas purging again: Nitrogen gas is introduced again to purge the deposition chamber and remove unreacted ethylene glycol and byproducts; The second to fifth steps were repeated 100 times, with a molecular layer deposition time of 0.5 hours, ultimately yielding a 20 nm thick tellurium-based organic compound film on the substrate. Figure 1 As shown, from Figure 1 As can be seen, a thin film has been formed on the surface of the substrate silicon wafer.

[0046] (III) Application The obtained tellurium-based organic compound film was irradiated with an EUV light source. After irradiation, it was developed, cleaned, and dried to obtain the pattern shown below. Figure 2 As shown, from Figure 2 The pattern can be seen to have formed after development.

[0047] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An extreme ultraviolet (EUV) photoresist, characterized in that, The extreme ultraviolet photoresist is a tellurium-based organic compound film, which is prepared by molecular layer deposition of tellurium organic compound precursors and organic ligands.

2. The extreme ultraviolet photoresist according to claim 1, characterized in that, The thickness of the extreme ultraviolet photoresist is 5nm~50nm.

3. The extreme ultraviolet photoresist according to claim 1, characterized in that, The amounts of the tellurium organic compound precursor and the organic ligand, expressed as a molar ratio of tellurium to the organic ligand, are 1:1 to 1:

4.

4. The extreme ultraviolet photoresist according to claim 1, characterized in that, The organic compound precursor of the tellurium is selected from one or more of ethanol tellurium, di(triethylsilyl) tellurium, di-tert-butyl tellurium, diethyl tellurium, and diisopropyl tellurium.

5. The extreme ultraviolet photoresist according to claim 1, characterized in that, The organic ligand is selected from one or more of diols, dicarboxylic acids, dithiols, and diamines.

6. A method for preparing an extreme ultraviolet (EUV) photoresist, characterized in that, The method for preparing the extreme ultraviolet photoresist according to any one of claims 1-5 comprises growing the tellurium-based organic compound thin film using a molecular layer deposition method, including the following steps: The first step is the pulsed generation of the organic compound precursor of tellurium: the organic compound precursor of tellurium is pulsed into the deposition chamber in the form of vapor, causing it to undergo chemical adsorption on the substrate surface; The second step is inert gas purging: inert gas is introduced to purge the deposition chamber and remove the unreacted organic compound precursor of the tellurium. The third step, the organic ligand pulse: the organic ligand is pulsed into the deposition chamber in the form of vapor, so that it reacts with the organic compound precursor of tellurium adsorbed on the substrate surface to form tellurium-based organic compounds; Fourth step, inert gas purging again: Inert gas is introduced again to purge the deposition chamber and remove unreacted organic ligand vapors and byproducts; Repeat steps one through four to obtain the tellurium-based organic compound film.

7. The method for preparing extreme ultraviolet photoresist according to claim 6, characterized in that, The molecular layer deposition temperature is 80℃~230℃, the molecular layer deposition time is 0.5h~8h, and the vacuum degree of molecular layer deposition is 0.1mbar~10mbar.

8. The method for preparing extreme ultraviolet photoresist according to claim 6, characterized in that, The single pulse duration of the tellurium organic compound precursor is 0.02s to 2s, the single pulse duration of the organic ligand is 0.05s to 5s, and the number of cycles is 30 to 300.

9. The method for preparing extreme ultraviolet photoresist according to claim 6, characterized in that, The preparation method further includes: Substrate pretreatment involves cleaning the substrate to remove surface contaminants and enrich its surface with hydroxyl groups; or, Substrate pretreatment involves cleaning the substrate to remove surface contaminants and enrich its surface with hydroxyl groups, followed by modification of the substrate using a silane coupling agent to enhance adhesion.

10. An application of an extreme ultraviolet (EUV) photoresist, characterized in that, The extreme ultraviolet photoresist according to any one of claims 1-5 is used to form photolithographic patterns in extreme ultraviolet lithography processes.

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