Method of forming an adhesion layer on a photoresist underlayer, structure including same, and system for forming an adhesion layer

Abstract

This invention discloses a method for forming a structure comprising a photoresist substrate and an adhesive layer, and a structure comprising the photoresist substrate and the adhesive layer. Several exemplary methods include forming the photoresist substrate and the adhesive layer using a cyclic deposition process. The adhesive layer can be formed in the same reaction chamber used to form the photoresist substrate.

Description

Technical Field

[0001] This invention generally relates to structures and methods of forming structures using photoresist. More specifically, this invention relates to structures comprising a photoresist substrate or formed using a photoresist substrate, and methods of forming such structures. Prior Technology

[0002] During the manufacturing of electronic devices, fine feature patterns can be formed on the substrate surface by patterning the substrate surface and etching materials from the substrate surface using processes such as vapor phase etching. As the device density on the substrate increases, there is an increasing need to form features with smaller dimensions.

[0003] Photoresist is commonly used to pattern the surface of a substrate before etching. By applying a layer of photoresist to the substrate surface, masking the photoresist surface, exposing the unmasked portion of the photoresist to radiation (such as ultraviolet light), and removing a portion (e.g., the unmasked or masked portion) of the photoresist, a pattern is formed in the photoresist while leaving a portion of the photoresist on the substrate surface.

[0004] Recently, techniques using extreme ultraviolet (EUV) wavelengths have been developed to develop patterns with relatively small features (e.g., 10 nm or smaller). To form features on a substrate using EUV, a photoresist underlayer is deposited onto the substrate surface, followed by an EUV photoresist layer deposited on top of the photoresist underlayer. Spin-on glass (SOG) is commonly used as an underlayer. Spin-on glass underlayers typically have a thickness of about 10 nm or greater. Recently, plasma-deposited oxides have been investigated as potential materials for photoresist underlayers. However, these oxides typically exhibit higher surface polarity than (e.g., EUV) photoresist. This difference in surface polarity can lead to pattern collapse. For at least these reasons, there is a need for improved structures containing a photoresist underlayer, such as underlayers suitable for use with EUV photoresist and methods for forming this structure.

[0005] Any problems and solutions discussed in this section are included in this invention only for the purpose of providing background information for the invention, and should not be construed as an admission that any or all of the discussion was known at the time of completion of this invention. Summary of the Invention

[0006] Various embodiments of the present invention relate to structures comprising a photoresist underlayer and an adhesive layer, and to methods of forming such layers and structures. While the various embodiments of the present invention address the shortcomings of prior methods and structures in more detail below, generally, the various embodiments of the present invention provide structures that may include a relatively thin, uniform photoresist underlayer having desired characteristics, such as desired etch selectivity, pattern quality, and / or pattern stability. Exemplary photoresist underlayers may be formed using a cyclic process (such as atomic layer deposition), which allows for precise control of the thickness of the photoresist underlayer, whether on a substrate surface or on different substrates. Furthermore, as described in more detail below, an additional adhesive layer may be formed to provide the required surface energy to facilitate the desired adhesion between the photoresist underlayer and the overlying photoresist.

[0007] According to an exemplary embodiment of the present invention, a method for forming a structure containing a photoresist underlayer includes providing a substrate in a reaction chamber, forming a photoresist underlayer over the surface of the substrate, and forming an adhesive layer over the photoresist underlayer. The adhesive layer is interposed between and contacts the photoresist underlayer and the photoresist layer. Various embodiments of the present invention may further include forming a (e.g., EUV) photoresist layer over the adhesive layer. The adhesive layer can be formed using a first cyclic deposition process, the cyclic deposition process including providing a silicon precursor to the reaction chamber, providing an inert gas to the reaction chamber, and using the inert gas to form a plasma to form an active material that reacts with the silicon precursor or its derivative to form the adhesive layer. The photoresist underlayer may include one or more of silicon and metals. For example, the photoresist substrate may include one or more of silicon oxide, silicon carbide, silicon nitride, silicon oxynitride, silicon carbonitride, silicon oxycarbonitride, metal oxide, metal nitride, metal carbon oxide, metal oxynitride, metal oxycarbonitride, and metal carbonitride. When the photoresist substrate contains silicon, the same or different silicon precursors can be used to form the photoresist substrate and the adhesion layer.

[0008] The photoresist underlayer can be formed using a second-cycle deposition process, such as a plasma-enhanced cycle (e.g., atomic layer) deposition process or a thermal cycle deposition process. The photoresist underlayer can have a thickness of less than 10 nm or less than 5 nm. The photoresist layer can be, for example, positive or negative extreme ultraviolet (EUV) lithography photoresist.

[0009] According to another exemplary embodiment of the present invention, a structure comprising a photoresist substrate and an adhesive layer is provided. The photoresist substrate and / or adhesive layer may be formed using methods as described herein. The photoresist substrate may include, for example, a layer containing metal and / or silicon. The adhesive layer may include silicon. The adhesive layer may have surface energy properties as described herein. An exemplary structure may also include a layer of photoresist (such as negative or positive EUV photoresist).

[0010] According to a further embodiment of the invention, a system for forming an adhesive layer is provided. Several exemplary systems include a reaction chamber, a silicon precursor source fluidly coupled to the reaction chamber, an inert gas source fluidly coupled to the reaction chamber, and a controller configured to perform the methods or portions thereof as described herein.

[0011] Those skilled in the art will understand these and other embodiments from the following detailed description of some embodiments with reference to the accompanying drawings. The invention is not limited to any of the specific embodiments disclosed. Simple Explanation of the Diagram

[0012] A more complete understanding of the exemplary embodiments of the present invention can be derived by referring to the embodiments and the claims when considered in conjunction with the following illustrative figures. Figure 1 schematically illustrates a method according to an exemplary embodiment of the present invention. Figure 2 illustrates a method according to an exemplary embodiment of the present invention. Figure 3 schematically illustrates a structure according to an exemplary embodiment of the present invention. Figure 4 schematically illustrates another structure according to an exemplary embodiment of the present invention. Figure 5 schematically illustrates a system configured to perform the method as described herein. Figure 6 schematically illustrates a system according to yet another example of the present invention. It should be understood that the elements in the figures are drawn for simplicity and clarity and are not necessarily drawn to scale. For example, the dimensions of some elements in the figures may be particularly enlarged relative to other elements to help improve the understanding of the illustrated embodiments of the present invention. Implementation

[0013] While some embodiments and examples are disclosed below, it should be understood that the invention extends beyond the specific embodiments and / or uses disclosed herein, as well as their obvious modifications and equivalents. Therefore, the scope of the invention disclosed herein should not be limited to the specific embodiments disclosed below.

[0014] This invention generally relates to a method of forming a structure comprising a photoresist underlayer and an adhesive layer, and to a structure comprising a photoresist underlayer and an adhesive layer. As described in more detail below, several exemplary methods can be used to form a structure having a photoresist underlayer and an adhesive layer, wherein desired characteristics are provided, such as desired photoresist underlayer thickness (e.g., less than 10 or less than 5 nm), relatively low surface roughness, good adhesion to the photoresist, desired etch selectivity, desired thickness uniformity within the substrate (e.g., wafer) and between the substrate, high pattern quality (low defect number and high pattern fidelity), low linewidth roughness (LWR), photoresist stability during EUV lithography processes (e.g., during any post-exposure bake (PEB)), photoresist development, substrate rework, reasonable EUV sensitivity, and integration compatibility (e.g., relatively low deposition temperature).

[0015] As used herein, the term "substrate" can refer to any underlying material, including and / or on which one or more layers may be deposited. A substrate may include bulk materials (such as silicon (e.g., single-crystal silicon)), other group IV materials (such as germanium), or compound semiconductor materials (such as GaAs), and may include one or more layers overlying or underlying the bulk material. For example, a substrate may include a patterned stack of several layers overlying the bulk material. The patterned stack may vary depending on the application. Furthermore, a substrate may additionally or alternatively include various features, such as recesses, wiring, etc., formed within or on at least a portion of a substrate layer.

[0016] In some embodiments, "film" refers to a layer extending in a direction perpendicular to the thickness direction. In some embodiments, "layer" refers to a material having a thickness formed on a surface, or a synonym for a thin film or non-thin film structure. A thin film or layer may consist of discrete single films or layers having certain properties or may consist of multiple films or layers, and the boundaries between adjacent films or layers may be clear or unclear, and may or may not be based on physical, chemical, and / or any other properties, formation process or sequence, and / or the function or purpose of adjacent films or layers. Furthermore, a layer or film may be continuous or discontinuous.

[0017] In this invention, "gas" may include materials that are gases, vaporized solids, and / or vaporized liquids at room temperature and pressure, and may consist of a single gas or a mixture of multiple gases depending on the context. Gases other than process gases (i.e., gases not introduced through gas distribution assemblies (such as spray heads), other gas distribution devices, etc.) may be used, for example, to seal reaction spaces, and may include sealing gases such as rare gases.

[0018] In some contexts, such as in the context of materials deposition, the term "precursor" can refer to a compound that participates in a chemical reaction to produce another compound, particularly a compound that forms the thin film matrix or the main framework of the thin film. However, the term "reactant" can refer to a compound that, in some cases, is distinct from the precursor, but activates, modifies, or catalyzes the precursor's reaction; the reactant can provide elements (such as O, N, C) to the thin film matrix and become part of the thin film matrix. In some cases, the terms precursor and reactant are used interchangeably. The term "inert gas" refers to a gas that does not participate in a chemical reaction to a significant extent and / or a gas that activates a precursor when, for example, RF or microwave power is applied, but unlike a reactant, it may not become part of the thin film matrix to a significant extent.

[0019] The term "cyclic deposition process" can refer to the process of sequentially introducing precursors (and / or reactants) into a reaction chamber to deposit a layer over a substrate, and includes processing techniques such as atomic layer deposition (ALD), cyclic chemical vapor deposition (cyclic CVD), and hybrid cyclic deposition processes that include an ALD assembly and a cyclic CVD assembly.

[0020] The term "atomic layer deposition" can refer to a vapor phase deposition process in which deposition cycles (typically multiple consecutive deposition cycles) are performed in a process chamber. When performed using alternating pulses of precursor / reactive gases and flushing (e.g., inert carrier) gases, the term "atomic layer deposition" as used herein also means processes referred to by related terms, such as chemical vapor deposition, atomic layer epitaxy (ALE), molecular beam epitaxy (MBE), gas source MBE, or organometallic MBE, and chemical beam epitaxy.

[0021] Typically, for ALD processes, during each cycle, a precursor system is introduced into the reaction chamber and chemisorbed onto the deposition surface (e.g., a substrate surface that may include previously deposited material from a previous ALD cycle or other materials), forming a monolayer or submonolayer material that is approximately non-reactive with additional precursors (i.e., self-limiting reaction). Subsequently, in some cases, a reactant (e.g., another precursor, a reactive gas, or an inert gas) may be introduced into the process chamber to convert the chemisorbed precursor into the desired material on the deposition surface. The reactant / inert gas can further react or interact with the precursor. A purge step may be used during one or more cycles (e.g., during each step of each cycle) to remove any excess precursor from the process chamber and / or any excess reactant and / or reaction byproducts from the reaction chamber.

[0022] In this invention, any two numbers of a variable may constitute the working range of the variable, and any range indicated may include or exclude endpoints. Additionally, any numerical value of the indicated variable (regardless of whether such numerical value is indicated as "about") may refer to an exact value or an approximate value and include equivalent values, and in some embodiments may refer to an average value, median value, representative value, multi-value, etc. Furthermore, in this invention, in some embodiments, the terms "comprising," "constituting," and "having" may independently mean "generally or broadly comprising," "including," "basically composed of," or "constituting of." According to the nature of the invention, any defined meaning of the terms does not necessarily exclude the ordinary and conventional meaning of such terms.

[0023] Please refer to the figures. Figure 1 illustrates a method 100 according to an exemplary embodiment of the present invention. Method 100 includes multiple steps such as providing a substrate (step 102), forming a photoresist underlayer (step 104), and forming an adhesive layer (step 106).

[0024] Step 102 includes providing a substrate (such as a substrate described herein). The substrate may include one or more layers to be etched, which include one or more material layers. For example, the substrate may include a deposited oxide, native oxide, or amorphous carbon layer to be etched. The substrate may include several layers underlying the material(s) to be etched.

[0025] During step 104, a photoresist underlayer is formed on the substrate surface. This photoresist underlayer can be formed using various techniques, including spin coating, chemical vapor deposition, and cyclic processing techniques. Compared to conventional spin-coated glass (SoG), plasma-processed SiO and SiOC materials have been identified as excellent options for photoresist underlayer materials due to their ability to achieve continuously thinner thicknesses and lower dry etch rates. Typically, PEALD is suggested conceptually as the best method for obtaining superior film thickness non-uniformity (%NU).

[0026] According to an exemplary embodiment of method 100, the photoresist underlayer is formed using a cyclic deposition process, such as an ALD process, for example, PEALD. This cyclic deposition process may include the use of active materials (e.g., formed from one or more of precursors, reactants, and / or inert gases), which are formed using one or more of direct and remote plasmas. Alternatively, step 104 may include a thermal cyclic deposition process. The use of a cyclic deposition process may be desirable because it allows the formation of a photoresist underlayer with a desired thickness (e.g., less than 10 nm or less than or approximately equal to 5 nm) and improved thickness uniformity (both within and between substrates). The use of a plasma-enhanced process may be desirable because, compared to a thermal process, a plasma-enhanced process allows the deposition of the photoresist underlayer material at relatively low temperatures and / or relatively high rates.

[0027] According to various embodiments of the present invention, the temperature in the reaction chamber during step 104 may be less than 500°C, less than 400°C, less than 300°C, or between about 100°C and about 500°C, or between about 150°C and about 300°C. The pressure in the reaction chamber during step 104 may be from about 1 Torr to about 100 Torr, from about 3 Torr to about 50 Torr, or from about 5 Torr to about 20 Torr.

[0028] According to an exemplary embodiment of the present invention, step 104 includes forming or depositing one or more of silicon or metal oxides, silicon or metal nitrides, and silicon or metal oxynitrides. Such oxides, nitrides, and / or oxynitrides may also include carbon.

[0029] The photoresist substrate may include, for example, one or more of silicon oxide, silicon carbide, silicon nitride, silicon oxynitride, silicon carbonitride, silicon oxycarbonitride, metal oxide, metal nitride, metal carbon oxide, metal oxynitride, metal oxycarbonitride, and metal carbonitride. The metal may include, for example, one or more metals selected from the group consisting of titanium, tantalum, tungsten, tin, and hafnium. In some cases, the photoresist substrate includes carbon. As photoresist substrate deposition and / or carbon treatment may be applied to the surface of the photoresist substrate, carbon may be incorporated into the photoresist substrate. Additionally or alternatively, a carbon-containing layer or other layer may be deposited on the surface of the photoresist substrate. The thickness of the photoresist substrate may be less than 10 nm, less than 5 nm, or greater than 3 nm and less than 10 nm.

[0030] A cyclic process for forming a photoresist underlayer suitable for step 104 is schematically illustrated in Figure 2 (sub-cycle x). Sub-cycle x may include (A) pulse a first precursor containing metal or silicon into the reaction chamber (step 202); and (B) pulse a second precursor or reactant containing an oxidizing agent and / or a nitriding agent into the reaction chamber (step 206). Sub-cycle x may be repeated, for example, between about 10 and about 50 or about 100 and about 200 times before step 106 is performed in method 100.

[0031] In some cases, the cyclic process for forming the photoresist underlayer may include (A) pulsed a first metal-containing precursor into the reaction chamber; (B) pulsed a second precursor or reactant containing an oxidizing agent and / or a nitriding agent into the reaction chamber; and (C) pulsed a carbon precursor into the reaction chamber. Each of the plurality of pulses may be separated by a blow-off step (204, 208). Furthermore, each pulse step or combination of pulse steps (e.g., pulse steps (A) and (B)) may be repeated multiple times before proceeding to the next step to adjust the composition of the photoresist underlayer. For example, the ratio of (AB):C may range from about 1:1 to about 1:10. Unless otherwise stated, steps (A) and (B) or steps (A), (B), and (C) may be performed in any order and various combinations of the steps may be repeated.

[0032] According to several exemplary embodiments of the present invention, a silicon-containing first precursor is provided. In some cases, the silicon precursor may also include carbon. Several exemplary silicon precursors suitable for forming photoresist underlayers include the silicon precursors described herein.

[0033] According to other exemplary embodiments of the invention, the first precursor comprises a metal. In these cases, the first precursor may comprise a transition metal, such as one or more metals selected from the group consisting of titanium, tantalum, tungsten, tin, and hafnium. The first precursor containing a metal may also comprise carbon (e.g., one or more organic groups directly or indirectly bonded to a metal atom). Specifically, the metal-containing first precursor may comprise a metal halide or an organometallic compound; or an organometallic compound, such as tetra(dimethylamino)titanium (TDMAT), titanium isopropoxide (TTIP), titanium chloride (TiCl), tetra(ethylmethylamino)hafnium (TEMAHf), hafnium chloride (HfCl), trimethylaluminum (TMA), triethylaluminum (TEA), other metal halides, or other metal-containing compounds, one or more.

[0034] The reactants may include an oxidizing reactant, a nitriding reactant, or a reducing agent, such as a hydrogen-containing reactant. Oxidizing and / or nitriding reactants include reactants containing one or more of oxygen and nitrogen. In some cases, the reactants may include both nitrogen and oxygen. Furthermore, in some cases, two or more oxidizing and / or nitriding reactants may be included in a single pulse. Examples of exemplary oxidizing and nitriding reactants include oxygen (O₂), water (H₂O), ozone (O₃), hydrogen peroxide (H₂O₂), ammonia (NH₃), diazepines (N₂H₂), CO₂, and nitrous oxide (N₂O); examples of exemplary hydrogen-containing reactants include hydrogen (H₂), etc. As described above, oxidizing and / or nitriding reactants may be exposed to (e.g., directly) plasma to form excited-state materials for the PEALD process.

[0035] When used, the carbon precursor may include any suitable organic compound, such as a carbon- and oxygen-containing compound. In some cases, the carbon precursor may also include nitrogen. The carbon precursor may be selected to react with, for example, the -OH terminal surface of a metal oxide and / or the -NH₂ terminal surface of a metal nitride. Several examples of suitable carbon precursors include one or more of organic compounds (such as acid anhydrides (e.g., acetic anhydride)), toluene, diethylene glycol, triethylene glycol, acetaldehyde, and organosilicon compounds (such as silanes and siloxanes). Several exemplary organosilicon compounds include (n,n-dimethylamino)trimethylsilane, trimethoxy(octadecyl)silane, hexamethyldisilazane, trimethoxy(3,3,3-trifluoropropyl)silane, trimethoxyphenylsilane, trichloro(3,3,3-trifluoropropyl)silane, and hexamethyldisilazane.

[0036] Once the photoresist underlayer is formed, an adhesion layer is formed during step 106. Step 106 can be performed in situ within the same reaction chamber without air and / or vacuum interruption.

[0037] As shown in Figure 1, step 106 may include multiple sub-steps such as providing a silicon precursor (step 108), providing an inert gas (step 110), and forming a plasma (step 112). Step 106 may include a cyclic deposition process, such as a PEALD process. For example, referring to Figure 2, step 106 may include pulse a silicon precursor into a reaction chamber (step 210), allowing the silicon precursor to react with the substrate surface, blowing away any unreacted precursor and / or byproducts (step 212), providing an inert gas to the reaction chamber, and using the inert gas to form a plasma to form an active material that reacts with the silicon precursor or its derivatives to form an adhesion layer (step 214), and blowing away any excess reactant and / or byproducts from the reaction chamber (step 216). As shown, sub-cycle y may be repeated multiple times, for example, between about 30 and about 40, or about 50, or about 60, or about 70, and about 120 times. For steps 102 and / or 104, the temperature and pressure during step 106 can be the same or similar. The thickness of the adhesive layer is greater than 0 and less than 2 nm.

[0038] During step 210, a silicon precursor is provided to the reaction chamber. According to various embodiments of the invention, the silicon precursor does not contain nitrogen. A nitrogen-free precursor can be advantageous for forming an adhesion layer because nitrogen is considered to have a poisoning effect due to the presence of N atoms. According to further embodiments, the silicon precursor consists of or is substantially composed of Si, C, H, and O, and can be provided to the reaction chamber with the assistance of a carrier gas. For example, the silicon precursor may be selected from one or more of the following groups: According to further examples, the silicon precursor system is selected from one or more of the following groups: 3-methoxypropyltrimethoxysilane, bis(trimethoxysilyl)methane, 1,2-bis(methyldimethoxysilyl)ethane, 1,2-bis(triethoxysilyl)ethane, 1,2-bis(triethoxysilyl)ethylene, 1,2-bis(diethoxymethylsilane). The silicon precursor may be alkyl)ethane, 1,2-bis(trimethoxysilyl)ethane, 1,1,3,3-tetramethoxy-1,3-disilcyclobutane, 1,1,3,3-tetraethoxy-1,3-disilcyclobutane, 1,1,3,3,5,5-hexamethoxy-1,3,5-trisilcyclohexane, or 1,1,3,3,5,5-hexaethoxy-1,3,5-trisilcyclohexane. Specifically, the silicon precursor may be or include 3-methoxypropyltrimethoxysilane. During step 210, the flow rate of the silicon precursor may be between about 100 sccm and about 150 sccm. The duration of step 210 may be between about 0.1 seconds and about 0.3 seconds.

[0039] During step 212, any excess silicon precursor and / or any reaction byproducts may be blown out of the reaction chamber. This can be done by supplying an inert gas to the reaction chamber and / or using a vacuum source.

[0040] During step 214, an inert gas is used to form a plasma. The inert gas may be or include one or more of Ar, He, Ne, Kr, and Xe. The power used to form the plasma may be from about 30 W to about 1000 W. The frequency of the plasma-forming power may be between about 200 kHz and about 2.45 GHz. The flow rate of the inert gas may be between about 2 slm and about 10 slm. The duration of step 214 may be between about 0.1 seconds (s) and about 2 seconds.

[0041] During step 216, the plasma power is turned off and any excess reactive material and / or byproducts are blown away. Subcycle y can be repeated multiple times to form a silicon-based adhesive layer of the desired thickness, for example, greater than 0 and less than about 2 nm.

[0042] Various methods according to the invention may also include a step of forming a photoresist layer overlying and contacting the adhesive layer. The photoresist may be deposited using, for example, a spin-coating technique. The photoresist layer may be or include positive or negative extreme ultraviolet (EUV) photoresist.

[0043] Figure 3 schematically illustrates a structure 300 according to an exemplary embodiment of the present invention. The structure 300 may be formed using, for example, methods 100 and / or 200.

[0044] As shown in the figure, structure 300 includes a substrate 302, a material layer 304, a photoresist underlayer 306, a photoresist layer 308, and an adhesive layer 310 inserted between and in contact with the photoresist underlayer 306 and the photoresist layer 308.

[0045] Substrate 302 may include the substrate described above. For example, substrate 302 may include a semiconductor substrate, such as a bulk material, such as silicon (e.g., single-crystal silicon); other group IV semiconductor materials; group III-V semiconductor materials; and / or group II-VI semiconductor materials, and may include one or more layers (e.g., patterned stacks) overlying the bulk material. Furthermore, as described above, substrate 302 may include various topologies, such as recesses, lines, etc., formed in or on at least a portion of the substrate layers.

[0046] Material layer 304 can be patterned and etched using a photoresist underlayer and a photoresist layer as described herein. Several exemplary materials suitable for material layer 304 include, for example, oxides, such as natural oxides or field oxides. Other exemplary materials for material layer 304 include amorphous carbon, nitrides, other oxides, silicon, and additional thin films (e.g., a self-polymerizing monolayer (e.g., hexamethyldisilazane (HMDS))).

[0047] The photoresist substrate 306 may include a photoresist substrate formed according to the methods described herein (e.g., method 100), and / or have the properties and / or materials described herein. Exemplary photoresist substrates include one or more of silicon or metal oxides, silicon or metal nitrides, and silicon or metal oxynitrides, any of which may or may not include carbon. For example, photoresist substrate 306 may include one or more of silicon oxide, silicon carbide, silicon nitride, silicon oxynitride, silicon carbonitride, silicon oxycarbonitride, metal oxide, metal nitride, metal carbon oxide, metal oxynitride, metal oxycarbonitride, and metal carbonitride.

[0048] The thickness of the photoresist underlayer 306 can depend on the composition of the material layer 304, the thickness of the material layer 304, the type of photoresist, etc. According to various embodiments of the invention, the thickness of the photoresist underlayer 306 is less than 10 nm, less than or about 5 nm, or between about 3 nm and about 10 nm. If the photoresist underlayer 306 is too thick, residual underlayer material may remain after the etching step. If the photoresist underlayer 306 is too thin, it may not be able to provide the required pattern transfer during the etching process.

[0049] Adhesive layer 310 ideally exhibits good adhesion and other properties as described herein. According to various embodiments of the invention, adhesive layer 310 comprises silicon and may selectively include one or more of carbon, hydrogen, and oxygen. As mentioned above, adhesive layer 310 may ideally not include nitrogen.

[0050] To provide the desired adhesion between photoresist layer 308 and photoresist underlayer 306, adhesive layer 310 may have, or be adapted to have, desired surface chemical properties, for example, quantified as surface energy, which is further classified into a polar portion and a dispersed portion of surface energy. The polar and dispersed portions of the surface energy of photoresist underlayer 306 can be determined by measuring the contact angle of a liquid (such as water or CH₂I₂) and using the Owens, Wendt, Rabel, and Kaelble (WORK) method. The same properties can be measured and calculated for photoresist layer 308. The thickness of adhesive layer 310 may be greater than 0 nm and less than 2 nm.

[0051] According to various embodiments of the present invention, the polar portion of the surface energy of the adhesive layer 310 is between about 5 mN / m and about 25 mN / m, or about 20 mN / m and about 40 mN / m. According to a further embodiment, the dispersed portion of the surface energy of the adhesive layer 310 is between about 10 mN / m and about 30 mN / m, or about 5 mN / m and about 25 mN / m, or about 20 mN / m and about 40 mN / m. For example, when the photoresist layer 308 comprises a negative photoresist, the polar portion of the surface energy of the photoresist substrate may be between about 20 mN / m and about 40 mN / m, and / or the dispersed portion of the surface energy of the photoresist substrate may be between about 10 mN / m and about 30 mN / m, or about 20 mN / m and about 40 mN / m. When the photoresist layer 308 includes a positive photoresist, the value of the polar portion of the surface energy of the photoresist layer can be between about 5 mN / m and about 25 mN / m, and / or the value of the dispersed portion of the surface energy of the photoresist layer can be between about 10 mN / m and about 30 mN / m.

[0052] For example, when using an inert gas plasma to form the adhesive layer 310, suspending bonds may act as surface reaction sites and lead to chemisorption when a silicon precursor is introduced onto the film. Therefore, ligands in the silicon precursor structure (e.g., CHx ligands) can ultimately remain on the surface, generating the desired surface free energy. The adhesive layer can essentially be SiOC, ultimately a surface hydrocarbon.

[0053] The photoresist layer 308 may be or include positive or negative (e.g., EUV) photoresist.

[0054] Figure 4 schematically illustrates scanning electron microscope (SEM) images of patterned photoresist formed on spin-coated glass and patterned photoresist formed on a PEALD silicon oxide layer having an adhesive layer as described herein. The thickness of the PEALD silicon oxide layer is approximately 4 nm (formed using approximately 50 deposition cycles), and the thickness of the adhesive layer is approximately 1 nm (formed using approximately 100 adhesive layer cycles). For the structure containing this adhesive layer, the full-range % inhomogeneity (NU) is 1.5%, and there are no defects (pattern collapse, microbridges, and microfractures) in the critical dimension (CD) of 16 nm. Furthermore, the linewidth roughness (LWR) and line edge roughness (LER) are as good as those of the 10 nm SoG.

[0055] Please refer to Figure 5, which further describes a system 500 configured to perform the methods described herein. System 500 includes at least one reaction chamber configured for depositing an underlayer and forming an adhesive layer as described herein. System 500 may include a first reaction chamber 511 and a second reaction chamber 512 configured for depositing an underlayer and forming an adhesive layer, or a portion thereof, as described herein. If desired, system 500 may include a third reaction chamber 513 in which another process, such as a thermal or plasma-enhanced post-processing, can be performed.

[0056] Figure 6 illustrates in more detail an exemplary reaction chamber (e.g., suitable for use as reaction chamber 511 or 512). Reactor system 600 can be used to perform one or more steps or sub-steps as described herein, and / or to form one or more structures or portions thereof as described herein.

[0057] The reactor system 600 includes a pair of parallel, mutually facing conductive plate electrodes 4, 2 within the interior 11 (reaction zone) of the reaction chamber 3. Plasma can be generated within the reaction chamber 3 by applying, for example, HRF power (e.g., 13.56 MHz or 27 MHz) from a power source 25 to one electrode (e.g., electrode 4) and electrically grounding the other electrode (e.g., electrode 2). A temperature regulator can be provided in the lower layer 2 (lower electrode) to maintain the temperature of the substrate 1 placed thereon at a desired temperature. Electrode 4 can serve as a gas distribution device, such as a spray plate. Reactant gas, dilution gas (if any), precursor gas, and / or the like can be introduced into the reaction chamber 3 via one or more of a gas line 20, a gas line 21, and a gas line 22, and through the spray plate 4. Although three gas lines are shown, the reactor system 600 may include any suitable number of gas lines. Gas line 20 can be coupled to a silicon precursor source 29, gas line 21 can be coupled to an inert gas source 27, and gas line 22 can be coupled to another (e.g., reactant) gas source 28.

[0058] In the reaction chamber 3, a circular pipe 13 with an exhaust line 7 is provided to discharge gas from the interior 11 of the reaction chamber 3. Furthermore, a sealing gas line 24 is provided through a transfer zone 5 located below the reaction chamber 3 to introduce sealing gas into the interior 11 of the reaction chamber 3 via the interior 16 (transfer zone) of the transfer zone 5, where a partition plate 14 is provided to separate the reaction zone and the transfer zone (a gate valve is omitted in this diagram; the wafer is transferred to or out of the transfer zone 5 through this gate valve). The transfer zone also has an exhaust line 6. In some embodiments, the deposition and processing steps are performed in the same reaction space, allowing two or more (e.g., all) of multiple steps (e.g., deposition and adhesion layers) to be performed continuously without exposing the substrate to air or other oxygen-containing environments.

[0059] In some embodiments, continuous flow of inert or carrier gas to reaction chamber 3 can be achieved using a flow-through system (FPS), wherein the carrier gas line has a manifold with a precursor reservoir (bottle), and the main line and the manifold are switched, wherein the manifold is closed when only carrier gas is intended to be fed to the reaction chamber, and the main line is closed when both carrier gas and precursor gas are intended to be fed to the reaction chamber, and the carrier gas flows through the manifold and exits from the bottle together with the precursor gas. Thus, the carrier gas can flow continuously into the reaction chamber, and the precursor gas can be carried in a pulsed manner by switching between the main line and the manifold, substantially preventing pressure fluctuations in the reaction chamber.

[0060] The reactor system 600 also includes one or more controllers 26, which are programmed or otherwise configured to perform one or more method steps as described herein. The controllers 26 communicate with various power supplies, heating systems, pumps, robots, and gas flow controllers or valves of the reactor, as will be understood by those skilled in the art. For example, controller 26 may be configured to control the gas flow rates of a silicon precursor and an inert gas to form an adhesion layer on a photoresist substrate. Additionally or alternatively, the controller may be configured to perform multiple steps to form a photoresist substrate as described herein.

[0061] In some embodiments, a dual-chamber reactor (two sections or compartments configured close to each other for processing wafers) may be used, wherein reactant gases and rare gases may be supplied through a common pipeline, while the precursor gas system may be supplied through a non-common pipeline.

[0062] The foregoing examples and embodiments of the present invention do not limit the scope of the invention, as these embodiments are merely examples of embodiments of the present invention. Any equivalent embodiments are intended to fall within the scope of the present invention. In fact, in addition to the embodiments shown and described herein, those skilled in the art will understand from this specification various modifications to the invention, such as substitutions for described elements and possible combinations. Such modifications and embodiments are also intended to fall within the scope of the invention claims.

[0063] 1:Substrate 2: Electrode / Lower Layer 3: Reaction Chamber 4: Electrode / Spray Plate 5: Transfer Area 6,7: Exhaust pipes 11: Internal 13: Round tube 14: Divider 16: Internal 20, 21, 22: Gas pipelines 24: Sealed gas pipeline 25: Power Supply 26: Controller 27: Inert gas source 28: Gas Source 29: Silicon precursor sources 100: Method 102: Steps 104: Steps 106: Steps 108: Steps 110: Steps 112: Steps 202: Steps 204: Steps 206: Steps 208: Steps 210: Steps 212: Steps 214: Steps 216: Steps 300: Structure 302:Substrate 304: Material layer 306: Photoresist bottom layer 308: Photoresist layer 310: Adhesive layer 500: System 511: First Reaction Chamber 512: Second Reaction Chamber 513: Third Reaction Chamber 600: Reactor System

Claims

1. A method for forming a structure containing a photoresist underlayer, the method comprising the following steps: providing a substrate in a reaction chamber; forming a photoresist underlayer covering the surface of the substrate, wherein the photoresist underlayer is composed of one or more of silicon oxide, silicon carbide, silicon nitride, silicon oxynitride, silicon carbonitride, and silicon oxycarbonitride; and forming an adhesive layer covering and contacting the photoresist underlayer using a first cycle deposition process, the steps of forming the adhesive layer comprising: providing a silicon precursor to the reaction chamber; providing an inert gas to the reaction chamber; and using the inert gas to form a plasma to form an active material that reacts with the silicon precursor or a derivative thereof, thereby forming the adhesive layer.

2. The method as described in claim 1, further comprising a step of forming a photoresist layer overlying on and contacting the adhesive layer, wherein the photoresist layer comprises extreme ultraviolet (EUV) lithography photoresist.

3. The method as described in claim 1, wherein the thickness of the photoresist substrate is greater than 3 and less than 10 nm.

4. The method as described in claim 1, wherein the first cycle deposition process is an atomic layer deposition process.

5. The method as described in claim 1, wherein the silicon precursor does not contain nitrogen.

6. The method as described in claim 1, wherein the silicon precursor is selected from one or more of the following groups:

7. The method as described in claim 1, wherein the silicon precursor is selected from one or more of the group consisting of: 3-methoxypropyltrimethoxysilane, bis(trimethoxysilyl)methane, 1,2-bis(methyldimethoxysilyl)ethane, 1,2-bis(triethoxysilyl)ethane, 1,2-bis(triethoxysilyl)ethylene, 1,2-bis(diethoxysilyl)ethylene, etc. Methylsilyl)ethane, 1,2-bis(trimethoxysilyl)ethane, 1,1,3,3-tetramethoxy-1,3-disilcyclobutane, 1,1,3,3-tetraethoxy-1,3-disilcyclobutane, 1,1,3,3,5,5-hexamethoxy-1,3,5-trisilcyclohexane, 1,1,3,3,5,5-hexaethoxy-1,3,5-trisilcyclohexane.

8. The method as described in claim 1, wherein the photoresist underlayer is formed using a second-cycle deposition process.

9. The method as described in claim 1, wherein the photoresist substrate is formed using the silicon precursor.

10. The method as described in claim 9, wherein the chemical formula of the silicon precursor is composed of Si, C, H and O.

11. The method as described in claim 1, wherein the first cycle deposition process is repeated between 30 and 40 or 50 or 60 or 70 and 120 times.

12. The method as described in claim 1, wherein the thickness of the adhesive layer is greater than 0 nm and less than 2 nm.

13. The method as described in claim 1, wherein the second cycle deposition process is repeated between 10 and 50 or between 100 and 200 times.

14. A structure formed by the method of claim 1, wherein the photoresist underlayer is composed of one or more of silicon oxide, silicon carbide, silicon nitride, silicon oxynitride, silicon carbonitride, and silicon oxycarbonitride, and the adhesive layer covers and contacts the photoresist underlayer.

15. The structure as described in claim 14, wherein the adhesive layer comprises silicon.

16. The structure as described in claim 14 or 15, further comprising an EUV photoresist covering and contacting the adhesive layer.

17. A system for forming an adhesive layer, the system comprising: a reaction chamber; a silicon precursor source fluidly coupled to the reaction chamber; an inert gas source fluidly coupled to the reaction chamber; and a controller configured to perform the method as described in claim 1.

Images