Structure including photoresist underlayer and method of forming same

Abstract

A method of forming a structure including a photoresist underlayer and a structure including a photoresist underlayer are disclosed. An exemplary method includes forming a photoresist underlayer using a cyclic deposition process. The example method may additionally include forming a passivation layer and / or an adhesion layer.

Description

Technical Field

[0001] The present disclosure generally relates to structures including a photoresist underlayer and methods of forming the same. Background Art

[0002] During the fabrication of electronic devices, finely patterned features can be formed on the surface of a substrate by patterning the surface of the substrate and etching material from the substrate surface using, for example, a vapor phase etching process. As the density of devices on a substrate increases, it is increasingly desirable to form features with smaller dimensions.

[0003] Photoresists are often used to pattern the surface of a substrate prior to etching. A pattern can be formed in a photoresist by applying a photoresist layer to the surface of a substrate, masking the surface of the photoresist, exposing unmasked portions of the photoresist to radiation (such as ultraviolet light), and removing a portion of the photoresist (e.g., the unmasked or masked portion) while leaving a portion of the photoresist on the substrate surface.

[0004] Recently, techniques have been developed to develop patterns with relatively small pattern features (e.g., 10 nm or less) using extreme ultraviolet (EUV) wavelengths. To form features on a substrate using EUV, a photoresist underlayer can be deposited onto the surface of the substrate, followed by deposition / coating of an EUV photoresist layer overlying the photoresist underlayer. The photoresist underlayer can be used to promote adhesion between the substrate surface and the photoresist. Increased adhesion can mitigate photoresist pattern collapse, photoresist scum, and other photoresist defects that might otherwise occur.

[0005] Spin-on glass (SoG) is often used as the underlayer. The SoG underlayer typically has a thickness of about 10 nm or greater. Therefore, SoG may be impractical for some applications.

[0006] Recently, plasma-deposited oxides have been investigated as possible materials for photoresist underlayers. However, such oxides typically exhibit a higher surface polarity than (e.g., EUV) photoresists and can cause damage to the underlying layer. Therefore, methods are desired to mitigate damage to the underlying material during the formation or deposition of a photoresist underlayer.

[0007] Recently, metal oxide resists (MORs) have been developed for EUV applications. Compared to conventional chemically amplified resists (CARs), MORs are believed to exhibit better resolution for both line / space and pillar patterning, and better local critical dimension (CD) uniformity (LCDU) on pillar patterns. Better resolution can lead to reduced process complexity and cost of manufacturing equipment. In addition, the use of refractory metal oxide barriers enables MORs to provide better pattern transfer for smaller features and thinner resists, and can achieve better etch durability and selectivity.

[0008] The EUV dose during the lithography process is typically much higher than the 193nm immersion (193i) lithography ArF (argon fluoride) that can be used with more traditional photoresists. EUV is typically higher because the number of EUV photos is only about 1 / 14 of the photons provided using the 193i ArF lithography process. The relatively low photo output may result in relatively large pattern roughness, which may lead to random defects in the photoresist pattern or device formed using this EUV technology. In addition, the high EUV dose results in relatively low throughput and is therefore not well suited for high-volume manufacturing. Therefore, it is desirable to use technologies with relatively high throughput EUV and MOR.

[0009] Any discussion of problems and solutions set forth in this section has been included in this disclosure merely to provide context for the disclosure and should not be construed as an admission that any or all of the discussion was known at the time the invention was made. Summary of the Invention

[0010] Various embodiments of the present disclosure relate to structures including a photoresist underlayer and methods of forming the photoresist underlayer and structures. While the following discusses in more detail how various embodiments of the present disclosure address shortcomings of existing methods and structures, generally speaking, various embodiments of the present disclosure provide a passivation layer that can protect an underlayer (e.g., a carbon layer, such as a carbon hardmask layer) during a method of forming the photoresist underlayer. Additionally or alternatively, an exemplary method may include forming the photoresist underlayer and a MOR covering the photoresist underlayer.

[0011] According to exemplary embodiments of the present disclosure, a method for forming a structure including a photoresist underlayer includes providing a substrate within a reaction chamber; passivating a surface of a carbon layer to form a passivated surface using a first cyclic process; and forming a bulk photoresist underlayer covering the passivated surface using a second cyclic process, wherein no oxidant is provided to the reaction chamber during the first cyclic process. The substrate may include a carbon layer, such as spin-on carbon (SoC), PECVD carbon, or the like, which may be suitable for use as a hardmask material. By omitting the oxidant during the first cyclic process, damage to the underlying carbon layer that may otherwise occur is mitigated. According to examples of these embodiments, the first cyclic process includes providing an inert gas to the reaction chamber, pulsing a precursor into the reaction chamber, and pulsing plasma power into the reaction chamber to form a plasma using the inert gas. The inert gas may be or include one or more of argon, helium, neon, krypton, xenon, ammonia, hydrazine, or any combination of hydrogen. According to further examples, the method may include purging the reaction chamber after pulsing the precursor and before pulsing the plasma power. In such cases, the plasma may be ignited after the purging step. According to yet further examples, the precursor comprises a silicon precursor, such as the silicon precursor mentioned below. According to yet further examples, the second cyclic process comprises providing a reactant to the reaction chamber, pulsing the precursor into the reaction chamber, and pulsing plasma power into the reaction chamber to form a plasma using the reactant. In these cases, the reactant can be or include oxygen. According to another example, the first cyclic process is repeated between about 10 cycles and about 500 cycles or between about 40 cycles and about 200 cycles. The (e.g., silicon) precursor used during the first cyclic process can be the same as the (e.g., silicon) precursor used during the second cyclic process.

[0012] According to another embodiment of the present disclosure, a method for forming a structure including a photoresist lower layer includes using a cyclic process to form a silicon oxycarbide lower layer covering the substrate, and forming a metal oxide resist layer covering the lower layer, wherein the silicon oxycarbide lower layer contains about 50 to about 55 atomic % oxygen. The silicon oxycarbide lower layer may additionally include about 10 to about 20 atomic % carbon. According to examples of these embodiments, the cyclic process includes providing reactants to a reaction chamber, pulsing a precursor into the reaction chamber, and pulsing plasma power into the reaction chamber to form a plasma using the reactants. According to a further example, the reactants include a hydrogen-containing gas and / or an oxygen-containing gas. According to a further example, the precursor includes a silicon precursor including a central carbon atom bonded to two silicon atoms and / or a silicon precursor including a silicon atom bonded to two oxygen atoms. The chemical formula of the (e.g., silicon) precursor may be composed of Si, C, H, and O. As described in more detail below, examples of the present disclosure may include a step of densifying the silicon oxycarbide lower layer. Further examples may include passivating the surface of the substrate, for example, by forming a passivation layer as described above.

[0013] According to other embodiments of the present disclosure, an adhesion layer may be formed between the photoresist underlayer and the photoresist layer (eg, MOR).

[0014] According to yet a further example, the photoresist lower layer comprises a bulk layer.The bulk layer may be densified.

[0015] These and other embodiments will become apparent to those skilled in the art from the following detailed description of certain embodiments having reference to the attached figures; the invention is not limited to any particular embodiment disclosed. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] A more complete understanding of exemplary embodiments of the present disclosure can be obtained by referring to the detailed description and claims when considered in conjunction with the following illustrative drawings.

[0017] Figure 1 A method according to an exemplary embodiment of the present disclosure is shown.

[0018] Figure 2 The structure of an exemplary embodiment according to the present disclosure is shown.

[0019] Figure 3 a) to c) in FIG. 1 show structures according to exemplary embodiments of the present disclosure.

[0020] Figure 4 a) and b) show the carbon loss and the passivation layer cycle number according to an exemplary embodiment of the present disclosure.

[0021] Figure 5 a) shows the thickness and carbon loss versus the number of bulk photoresist underlayer deposition cycles, Figure 5 b) shows the thickness and carbon loss versus the number of bulk photoresist underlayer deposition cycles, and Figure 5 Figure c) shows the number of culture cycles and the number of passivation layer cycles.

[0022] Figure 6 a) shows carbon loss versus passivation layer cycle number for a porous carbon hard mask material according to an exemplary embodiment of the present disclosure, and Figure 6 FIG. 2 b) shows carbon loss versus passivation layer cycle number for a dense carbon hard mask material according to an exemplary embodiment of the present disclosure.

[0023] Figure 7 Another method according to an exemplary embodiment of the present disclosure is shown.

[0024] Figure 8 A deposition process according to an exemplary embodiment of the present disclosure is shown.

[0025] Figure 9A and 9BDefect and critical dimensions are shown for various process conditions.

[0026] Figure 10 a) shows the dose and oxygen concentration according to another example of the present disclosure, Figure 10 FIG. 2 b) shows carbon and oxygen concentrations in atomic % according to another example of the present disclosure.

[0027] Figure 11 Exemplary reactor systems according to further examples of the present disclosure are shown.

[0028] It should be understood that the elements in the drawings are shown for simplicity and clarity and are not necessarily drawn to scale. For example, the sizes of some elements in the drawings may be exaggerated relative to other elements to help improve understanding of the illustrated embodiments of the present disclosure. DETAILED DESCRIPTION

[0029] Although certain embodiments and examples are disclosed below, it should be understood that the invention extends beyond the specifically disclosed embodiments and / or their uses and obvious modifications and equivalents thereof. Therefore, it is intended that the scope of the disclosed invention should not be limited by the specific disclosed embodiments described below.

[0030] The present disclosure generally relates to methods for forming structures including a photoresist underlayer and structures including a photoresist underlayer. As described in more detail below, exemplary methods can be used to form structures having a photoresist underlayer that provide desirable properties, such as a desired photoresist underlayer thickness (e.g., less than 10 or less than 5 nm), relatively low surface roughness, good adhesion to the photoresist, desirable etch selectivity, desirable thickness uniformity—within a substrate (e.g., a wafer) and between substrates, high pattern quality (low defect count and high pattern fidelity), low line width roughness (LWR), photoresist stability during EUV lithography processing (e.g., during any post-exposure bake (PEB), photoresist development, substrate rework), reasonable EUV sensitivity, compatibility with integration (e.g., relatively low deposition temperature), reduced damage to underlying (e.g., carbon) layers, and / or use of a relatively low dose (e.g., less than that used for spin-on-glass photoresist underlayers), particularly when used in conjunction with a metal oxide resist (MOR).

[0031] As used herein, the term "substrate" may refer to any one or more underlying materials including and / or on which one or more layers may be deposited. The substrate may comprise a bulk material, such as silicon (e.g., single crystal silicon), other Group IV materials (e.g., germanium), or compound semiconductor materials (e.g., GaAs), and may comprise one or more layers overlying or underlying the bulk material. For example, the substrate may comprise a patterned stack of several layers covering the bulk material. The patterned stack may vary depending on the application. Furthermore, the substrate may additionally or alternatively include various features, such as recesses, lines, etc., formed in or on at least a portion of a layer of the substrate. According to some examples, the substrate includes a surface or surface layer comprising a layer of carbon material, such as spin-on carbon (SoC), PECVD carbon, etc.

[0032] In some embodiments, "film" refers to a layer extending in a direction perpendicular to the thickness direction. In some embodiments, "layer" is a synonym for a material or film or non-film structure having a certain thickness formed on a surface. A film or layer may be composed of a discrete single film or layer or multiple films or layers having certain properties, and the boundaries between adjacent films or layers may or may not be clear and may or may not be established based on the physical, chemical and / or any other properties, formation process or sequence and / or function or purpose of adjacent films or layers. In addition, a layer or film may be continuous or discontinuous.

[0033] In the present disclosure, "gas" may include materials that are gaseous at normal temperature and pressure, evaporated solids, and / or evaporated liquids, and may be composed of a single gas or a gas mixture, depending on the circumstances. Gases other than process gases (i.e., gases introduced without passing through a gas distribution component (such as a showerhead, other gas distribution devices, etc.)) may be used, for example, to seal the reaction space and may include sealing gases, such as noble gases.

[0034] In some cases, such as in the context of material deposition, the term "precursor" may refer to a compound that participates in a chemical reaction to produce another compound, and in particular, a compound that constitutes the membrane matrix or the main skeleton of the membrane, while the term "reactant" may refer to a compound that, in some cases other than a precursor, activates a precursor, modifies a precursor, or catalyzes a reaction of a precursor; a reactant may contribute elements (e.g., O, N, C) to the membrane matrix and become part of the membrane matrix. In some cases, the terms precursor and reactant may be used interchangeably. The term "inert gas" refers to a gas that does not participate in a chemical reaction to an appreciable extent and / or a gas that excites a precursor when, for example, RF or microwave power is applied, but, unlike a reactant, may not become part of the membrane matrix to an appreciable extent.

[0035] The term "cyclic deposition process" or "cyclic deposition process" may refer to the sequential introduction of precursors (and / or reactants) into a reaction chamber to deposit layers on 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 component and a cyclic CVD component.

[0036] The term "atomic layer deposition" may refer to a vapor deposition process in which a deposition cycle, typically a plurality of continuous deposition cycles, is performed in a processing chamber. As used herein, the term atomic layer deposition also refers to a process comprising a precursor / reactive gas and a purge gas (e.g., an inert carrier gas) with alternating pulses and / or a pulse for generating plasma power. Typically, for an ALD process, during each cycle, a precursor is introduced into the reaction chamber and chemically adsorbed onto a deposition surface (e.g., a substrate surface that may include a previously deposited material or other material from a previous ALD cycle) to form a monolayer or sub-monolayer of a material that is not easily reacted with another precursor (i.e., a self-limiting reaction). Thereafter, in some cases, a reactant (e.g., another precursor or reactive gas or inert gas) may be subsequently introduced into the processing chamber for converting the chemically adsorbed precursor into the desired material on the deposition surface. The reactant / inert gas may be able to further react or interact with the precursor. During one or more cycles, for example, during each step of each cycle, a purge step may be used to remove any excess precursor from the processing chamber and / or remove any excess reactant and / or reaction byproducts from the reaction chamber.

[0037] In the present disclosure, any two numerals of a variable can constitute the working range of a variable, and any range indicated can include or exclude endpoints. In addition, any value of the variable indicated (regardless of whether they are indicated with "about") can refer to an exact value or an approximate value and include equivalents, and in some embodiments can refer to an average value, a median, a representative value, a majority value, etc. For example, the term "about" can refer to + / - 20%, 10%, 5%, 2% or 1% of a value. In addition, in the present disclosure, the terms "including," "consisting of," and "having" can independently refer to "typically or extensively comprising," "comprising," "substantially consisting of," or "consisting of" in some embodiments. According to the various aspects of the present disclosure, the meaning of any definition of a term does not necessarily exclude the common and customary meaning of a term.

[0038] Turning now to the accompanying drawings, Figure 1A method 100 for forming a structure including a photoresist underlayer according to an exemplary embodiment of the present disclosure is shown. Method 100 includes the following steps: providing a substrate (step 102), passivating a surface of a carbon layer to form a passivated surface using a first cycle process (step 104), and forming a bulk photoresist underlayer covering the passivated surface using a second cycle process (step 106). Method 100 may also include one or more of: forming an adhesion layer (step 108), a densification layer (step 110), and / or forming a metal oxide resist (MOR) layer (step 112).

[0039] Step 102 includes providing a substrate, such as the substrate described herein, within a reaction chamber. According to examples of these embodiments, the substrate includes a top layer or surface comprising carbon. As an example, the substrate may include a layer of carbon material, such as spin-on carbon (SoC), PECVD carbon, etc. The substrate may include several layers below the carbon material layer. The reaction chamber may be combined as follows: Figure 11 As stated.

[0040] During step 104, the surface of the substrate is passivated using a first cyclic process to form a passivated surface. Step 104 may include forming a passivation layer. However, in some cases, the passivation layer may not be detectable.

[0041] Typically, a passivation layer is formed between the carbon layer and the underlying bulk photoresist layer (sometimes referred to herein as the underlayer). The passivation process includes a less aggressive oxygen-free plasma process to mitigate damage that might otherwise occur to the carbon material layer. Therefore, according to an example, no oxidant is provided to the reaction chamber during the first cycle.

[0042] The first cycle process may include, for example, pulsing a precursor into the reaction chamber and / or pulsing plasma power into the reaction chamber to form a plasma using an inert gas. For example, the first cycle process includes providing an inert gas to the reaction chamber, pulsing a precursor into the reaction chamber, and pulsing plasma power into the reaction chamber to form a plasma using an inert gas. In some cases, the inert gas may be a carrier gas provided with the precursor. In some cases, an inert gas may also be provided before and / or after the precursor and / or reactant pulsing, for example to purge the reaction chamber. For example, method 100 may include purging the reaction chamber after the step of pulsing the precursor and before and / or after pulsing the plasma power. According to an example, an inert gas may be used as a reactant. The inert gas may be or include one or more of argon, helium, neon, krypton, xenon, ammonia, hydrazine, or any combination of hydrogen. For example, the inert gas may be argon. According to a further example, after pulsing the precursor into the reaction chamber, the plasma is ignited after the step of purging the reaction chamber.

[0043] The temperature within the reaction chamber during step 104 may be between about 50° C. and about 380° C. or between about 75° C. and about 190° C. The pressure within the reaction chamber during step 104 may be between about 200 Pa and about 1300 Pa or between about 330 Pa and about 1000 Pa. The plasma (e.g., Rf) power during the plasma pulse may be between about 20 W and about 1000 W or between about 35 W and about 500 W.

[0044] According to a further example, the precursor comprises a silicon precursor. An exemplary silicon precursor suitable for step 104 comprises oxygen. The duration of the precursor pulse can be from about 0.1 s to about 5 s. The flow rate of the (e.g., silicon) precursor to the reaction chamber can be from about 10 sccm to about 6000 sccm.

[0045] The number of cycles in the first cycle may be selected to mitigate carbon loss from the lower carbon layer. Figure 3 Figures a) to c) show structures 302, 304, 306 including a substrate 308 having a carbon material layer 310 thereon. Figure 3 FIG. 3 a) shows a structure 302 having a carbon material. Figure 3 FIG. 3 b) shows structure 304 after forming a passivation layer 314 on structure 302. As shown, little to no carbon material layer 310 is removed during the formation of passivation layer 314. In contrast, Figure 3 As shown in c), if the body layer 316 is formed directly on the carbon material layer, the carbon material layer 310 is reduced to the carbon material layer 312.

[0046] Figure 4 Figure a) shows the carbon loss measured during the deposition of various 5 nm bulk lower layer materials, with various numbers of passivation and bulk lower layer material cycles. Thus, as the number of protection cycles increases, the number of bulk deposition cycles using O2 plasma decreases. Carbon loss decreases sharply from 0 (no protection) to 60 cycles of protection deposition, while for additional cycles, carbon loss tends to increase slightly. This clear U-shaped curve reveals the presence of two (2) competing phenomena with opposite effects on carbon loss.

[0047] exist Figure 4 In the first part of the curve in a), the protective layer effectively manages to reduce carbon losses. Figure 4 b) reveals that due to the significant incubation period during deposition on the SoC, there is no actual deposition of protection during the first 57 cycles. This indicates that there must be a passivation / hardening of the SoC caused by the protective layer process - i.e., a passivation of the surface.

[0048] Figure 5Figure a) reveals a decrease in the thickness of the underlying layer and rapid carbon loss during the first 25 cycles of bulk layer deposition. This is likely due to etching of the carbon-rich protective layer by the O2 plasma used during bulk deposition. When the number of bulk deposition cycles is above about 50-75, the carbon loss is systematically lower when using a thinner 100-cycle protective layer, as shown in Figure 5a. Figure 5 This may be related to the etching and regrowth observed in the first 50 cycles of bulk deposition. This incubation period increases with the number of protective deposition cycles as shown in Figure 2b. Figure 5 Longer incubations will result from longer etching times for thick protective layers and may lead to higher carbon losses.

[0049] Carbon loss from different carbon-rich substrates: Porous and dense PECVD-grown CHMs Figure 6 In this case, the bulk cycle is fixed at 74 and the guard deposition cycle is varied while the total thickness remains in the range of 5-6 nm. Figure 6 a)) in the figure shows that the dense CHM ( Figure 6 b) shows lower carbon loss. Both substrates show similar U-shaped curves, with carbon loss reaching a minimum at approximately 60-70 cycles of protective deposition. In the case of porous CHMs, carbon loss increases very rapidly above 70 protective cycles. Therefore, it is desirable to precisely know the location of the minimum carbon loss. According to examples of the present disclosure, the first cycling process is performed between approximately 50 and approximately 80 cycles, or between approximately 60 and approximately 70 cycles.

[0050] Turn again Figure 1 , during step 106, a bulk photoresist underlayer is formed on the surface of the substrate using a second cyclic process. The cyclic deposition process may include the use of an activated species (e.g., formed from one or more of a precursor, a reactant, and / or an inert gas) formed using one or more of a direct plasma and a remote plasma. Alternatively, step 106 may include a thermal cyclic deposition process. The use of cyclic deposition processes may be desirable because they allow the formation of a photoresist underlayer having a desired thickness (e.g., less than 10 nm or less than or approximately equal to 5 nm) within and between substrates with improved thickness uniformity. The use of a plasma enhanced process may be desirable because it allows the deposition of the photoresist underlayer material at a relatively low temperature and / or a relatively high rate compared to a thermal process.

[0051] According to an exemplary embodiment of the present disclosure, step 106 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.

[0052] The photoresist lower layer may include, for example, one or more of the following: silicon oxide, silicon oxycarbide, silicon nitride, silicon oxynitride, silicon carbonitride, silicon carbonitride, silicon oxycarbon nitride, metal oxide, metal nitride, metal oxycarbide, metal oxynitride, metal oxycarbon nitride and metal carbonitride. The metal may include, for example, one or more metals selected from the following: titanium, tantalum, tungsten, tin and hafnium. In some cases, the photoresist lower layer includes carbon. When depositing the photoresist lower layer, carbon can be incorporated into the photoresist lower layer and / or a carbon treatment can be applied to the surface of the photoresist lower layer. Additionally or alternatively, a carbon-containing layer or other layer can be deposited on the surface of the photoresist lower layer. The thickness of the photoresist lower layer can be less than 10nm, less than 5nm, or greater than 3nm and less than 10nm.

[0053] A cyclic process for forming the photoresist underlayer suitable for step 106 includes providing a reactant to a reaction chamber (e.g., continuously through one or more cycles), pulsing a precursor into the reaction chamber, and pulsing plasma power into the reaction chamber to form a plasma using the reactant. Prior to performing method 100, the number of cycles of step 106 may be between about 10 and about 50, or between about 100 and about 200.

[0054] In some cases, a cyclic process for forming a photoresist lower layer may include (A) pulsing a first precursor comprising a metal into a reaction chamber, (B) pulsing a second precursor or reactant comprising an oxidizing agent and / or a nitriding agent into the reaction chamber, and (C) pulsing a carbon precursor into the reaction chamber. Each pulse may be separated by a purge step (e.g., by providing an inert gas to the reaction chamber). Furthermore, each pulse step or combination of pulse steps may be repeated multiple times before proceeding to the next step to adjust the composition of the photoresist lower layer.

[0055] According to an exemplary aspect of the present disclosure, a first precursor comprising silicon is provided. In some cases, the silicon precursor may further comprise carbon. Exemplary silicon precursors suitable for forming a photoresist underlayer are described below.

[0056] According to other exemplary aspects of the present disclosure, the first precursor includes a metal. In these cases, the first precursor may include a transition metal, such as one or more metals selected from titanium, tantalum, tungsten, tin and hafnium. The first precursor comprising a metal may also include carbon—such as one or more organic groups directly or indirectly bonded to a metal atom. As a specific example, the first precursor comprising a metal may include a metal halide or a metal organic compound, or an organometallic compound, such as one or more of the following: tetrakis(dimethylamino)titanium (TDMAT), titanium isopropoxide (TTIP), titanium chloride (TiCl), tetrakis(ethylmethylamino)hafnium (TEMAHf), hafnium chloride (HfCl), trimethylaluminum (TMA), triethylaluminum (TEA), other metal halides or other metal-containing compounds.

[0057] The reactants may include oxidizing reactants, nitriding reactants, or reducing agents, such as hydrogen-containing reactants. Oxidizing and / or nitriding reactants include reactants comprising one or more of oxygen and nitrogen. In some cases, the reactants may include both nitrogen and oxygen. Also, in some cases, two or more oxidizing and / or nitriding reactants may be included in a single pulse. Exemplary oxidizing and nitriding agents include oxygen (O2), water (H2O), ozone (O3), hydrogen peroxide (H2O2), CO2, nitrous oxide (N2O); exemplary hydrogen-containing reactants include hydrogen (H2), etc. As described above, the oxidizing and / or nitriding reactants may be exposed to (e.g., directly) plasma to form excited species for the PEALD process.

[0058] When used, the carbon precursor can include any suitable organic compound, for example, a compound comprising carbon and oxygen. In some cases, the carbon precursor can also include nitrogen. The carbon precursor can be selected to react with the -OH end-capping surface of, for example, a metal oxide and / or the -NH2 end-capping surface of a metal nitride. The example of a suitable carbon precursor includes one or more organic compounds, such as anhydrides (such as acetic anhydride), toluene, diethylene glycol, triethylene glycol, acetaldehyde and organosilicon compounds, such as silanes and siloxanes. Exemplary organosilicon compounds include (n, n-dimethylamino) trimethylsilane, trimethoxy (octadecyl) silane, hexamethyldisilazane, trimethoxy (3,3,3-trifluoropropyl) silane, trimethoxyphenyl silane, trichloro (3,3,3-trifluoropropyl) silane and hexamethyldisilazane.

[0059] The temperature within the reaction chamber during step 106 may be between about 50° C. and about 380° C. or between about 75° C. and about 190° C. The pressure within the reaction chamber during step 106 may be between about 200 Pa and about 1300 Pa or between about 300 Pa and about 800 Pa. The plasma (e.g., Rf) power during the plasma pulse may be between about 20 W and about 1000 W or between about 35 W and about 200 W. The plasma power may be higher or lower than the plasma power in step 104.

[0060] Once the bulk photoresist underlayer is formed during step 106, the adhesion layer may be formed during step 108. Step 108 may be performed in situ within the same reaction chamber and without air and / or vacuum breaks.

[0061] Step 108 may include the sub-steps of providing a silicon precursor, providing an inert gas, and forming (e.g., pulsing plasma power) a plasma. Step 108 may include a cyclic deposition process, such as a PEALD process. For example, step 108 may include pulsing a silicon precursor into a reaction chamber, allowing the silicon precursor to react with the surface of the substrate, purging any unreacted precursor and / or byproducts, providing an inert gas to the reaction chamber (e.g., continuously during one or more cycles), and using the inert gas to form a plasma to form activated species that react with the silicon precursor or its derivatives to form an adhesion layer, and purging any excess reactive species and / or byproducts from the reaction chamber. Step 108 may be performed multiple times—e.g., between about 10 and about 100, or about 100, or about 200, or about 200 and about 500 times. The temperature and pressure during step 106 may be the same or similar to those of steps 102 and / or 104. The thickness of the adhesion layer is greater than 0 and less than 2 nm.

[0062] According to an example of the present disclosure, the silicon precursor provided during step 108 does not contain nitrogen. A precursor that does not contain nitrogen may be beneficial for forming the adhesion layer because nitrogen is believed to exhibit a poisoning effect due to the presence of nitrogen atoms. According to a further example, the silicon precursor consists of or consists essentially of Si, C, H, and O, which may be provided to the reaction chamber with the aid of a carrier gas. For example, the silicon precursor may be selected from one or more of the following:

[0063]

[0064] According to further examples, the silicon precursor is selected from one or more of the following: 3-methoxypropyltrimethoxysilane, bis(trimethoxysilyl)methane, 1,2-bis(methyldimethoxysilyl)ethane, 1,2-bis(triethoxysilyl)ethane, 1,2-bis(triethoxysilyl)ethylene, 1,2-bis(diethoxymethylsilyl)ethane, 1,2-bis(trimethoxysilyl)ethane, 1,1,3,3-tetramethoxy-1,3-disilacyclobutane, 1,1,3,3-tetraethoxy-1,3-disilacyclobutane, 1,1,3,3,5-hexamethoxy-1,3,5-trisilacyclohexane, 1,1,3,3,5-hexaethoxy-1,3,5-trisilacyclohexane. As a specific example, the silicon precursor may be or include 3-methoxypropyltrimethoxysilane. During step 210, the flow rate of the silicon precursor may be between about 10 sccm and about 6000 sccm. The duration of the silicon precursor pulse may be between about 0.1 s and about 5 s.

[0065] The power used to form the plasma can be between about 30 W and about 1000 W. The frequency of the power used to form the plasma can be between about 200 kHz and about 2.45 GHz. The flow rate of the inert gas can be between about 2 slm and about 10 slm. The duration of the plasma pulse can be between about 0.1 s and about 10 s.

[0066] During step 110, the bulk adhesion layer formed during step 108 may be densified. Although shown as a separate step, densification may be achieved by changing the deposition parameters of the bulk underlayer to obtain a denser bulk layer, using a higher temperature (e.g., between about 100° C. and about 500° C. or between about 150° C. and about 380° C.) to deposit the bulk underlayer (e.g., within a higher temperature range), performing a thermal annealing process (above 100° C. and below 1000° C.) under an inert or oxygen atmosphere, or performing a UV cure to densify the photoresist underlayer.

[0067] Densification of the bulk layer (and optionally the adhesion layer) is believed to result in higher generation of secondary electrons during photoresist exposure due to the higher presence of oxygen atoms per unit area. The dose decreases with increasing O% likely because O can generate more secondary electrons than Si and C. Secondary electrons can accelerate the reaction during resist exposure, thus requiring fewer photons for the target CD without increasing any contaminants.

[0068] As shown, method 100 may also include step 112 of forming a photoresist layer covering and contacting the adhesion layer and / or the dense layer. The photoresist may be a MOR, which may be deposited using, for example, spin coating or a vapor phase process. The thickness of the MOR may be between about 10 and about 50 nm or between about 20 and about 40 nm.

[0069] Figure 2 A structure 200 is shown according to an exemplary embodiment of the present disclosure. The structure 200 can be formed using the method 100, for example.

[0070] As shown, structure 200 includes a substrate 202 , a carbon material layer 204 , a passivation layer 206 , a bulk photoresist underlayer 208 , a photoresist layer 212 , and an adhesion layer 210 interposed between and in contact with the photoresist underlayer 208 and the photoresist layer 212 .

[0071] The substrate 202 may include a substrate as described above. The carbon material layer 204 may be or include any carbon material as described herein. The carbon material layer 204 may be or include a hard mask material. For example, the carbon material layer 204 may include amorphous carbon or an additional film such as a self-assembled monolayer (e.g., hexamethyldisilazane (HMDS)).

[0072] The passivation layer 206 may be formed according to the above step 104. According to an example of the present disclosure, the passivation layer 206 includes silicon and carbon.

[0073] The photoresist underlayer 208 may include a photoresist underlayer formed according to the methods described herein and / or have properties and / or materials as described herein. Exemplary photoresist underlayers 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, the photoresist underlayer 208 may include one or more of silicon oxide, silicon oxycarbide, silicon nitride, silicon oxynitride, silicon carbonitride, silicon oxycarbonitride, metal oxide, metal nitride, metal oxycarbide, metal oxynitride, metal oxycarbonitride, and metal carbonitride.

[0074] The thickness of the photoresist lower layer 208 may depend on the composition of the material layer 204, the thickness of the material layer 204, the type of photoresist, etc. According to an example of the present disclosure, the photoresist lower layer 208 has a thickness of less than 10 nm, or less than or about 5 nm, or between about 3 nm and about 10 nm. If the photoresist lower layer 306 is too thick, residual lower layer material may remain after the etching step. If the photoresist lower layer 306 is too thin, the photoresist lower layer 306 may not provide the desired pattern transfer during the etching process.

[0075] Adhesion layer 210 desirably exhibits good adhesion and other properties as described herein. According to an example of the present disclosure, adhesion layer 210 includes silicon and may optionally include one or more of carbon, hydrogen, and oxygen. As described above, adhesion layer 210 may desirably not include nitrogen.

[0076] The photoresist layer 212 may be or include MOR. As a specific example, the photoresist layer 212 may be Sn-containing MOR.

[0077] Now turn Figure 7 , shows another method 700 for forming a structure including a photoresist lower layer according to an example of the present disclosure. Method 700 includes providing a substrate in a reaction chamber using a cyclic process (step 702), forming a silicon oxycarbide lower layer covering the substrate (step 704), and forming a metal oxide resist layer covering the lower layer (step 710). According to an example of the present disclosure, the silicon oxycarbide lower layer contains about 50 to about 55 atomic % oxygen. As shown, method 700 may also include forming one or more of an adhesion layer (step 706), a densification layer (step 708), and / or a passivation layer (step 712).

[0078] Step 702 may be the same as or similar to step 102 described above. When the substrate includes a carbon layer or surface, method 700 may include step 712, which may be the same as or similar to step 104 described above.

[0079] During step 704, a silicon oxycarbide (SiOC) underlayer is formed. As described in more detail below, the PEALD SiOC photoresist underlayer formed according to step 704 exhibits lower dose requirements than spin-on-glass (SoG), the current standard underlayer used in HVM, with comparable lithographic performance. In an exemplary embodiment, the SiOC photoresist underlayer contains only Si, O, and C. Therefore, the use of such an underlayer does not cause issues with metal doping and dry resist.

[0080] The temperature within the reaction chamber during step 704 can be between about 50° C. and about 380° C. or between about 75° C. and about 190° C. The pressure within the reaction chamber during step 704 can be between about 200 Pa and about 1300 Pa or between about 300 Pa and about 1000 Pa. The plasma (e.g., Rf) power during the plasma pulse can be between about 30 W and about 1000 W or between about 50 W and about 500 W. The plasma power can be higher or lower than the plasma power in step 712. The duration of the plasma power step (e.g., step 806) can be between about 0.1 s and about 5 s.

[0081] An exemplary loop process 800 applicable to step 704 is Figure 8 The cyclic process 800 includes providing a silicon precursor to a reaction chamber to perform a silicon precursor pulse (step 802), purging the reaction chamber (step 804), forming a plasma (step 806), and purging reactive species (step 808).

[0082] During step 802, a silicon precursor is provided to the reaction chamber during a pulse period. According to an example of the present disclosure, the chemical formula of the precursor consists of Si, C, H, and O. Suitable silicon precursors for step 802 include, for example, one or more silicon precursors selected from the following:

[0083] (i)

[0084] wherein n is 1 or 2, and each R is independently selected from C1-C2 alkyl;

[0085] (ii)

[0086] wherein n is 1 or 2, and each of R1 and R2 is independently selected from a C1-C2 alkyl or alkene functional group;

[0087] (iii)

[0088] wherein n is 1 or 2, and each of R1 and R2 is independently selected from a C1-C2 alkyl or alkene functional group; or

[0089] (iv) .

[0090] The duration of the pulse period may be from about 0.1 s to about 5 s or between about 0.15 and about 2 s.

[0091] The reactant may be or include an inert gas and / or an oxidant and / or a reducing gas. The reactant may flow continuously to the reaction chamber during one or more cycles of step 704. In some cases, the reactant may be or include one or more of a hydrogen-containing gas (e.g., H2, NH3, etc.), an oxygen-containing gas (e.g., N2O, CO2, etc.), and / or an inert gas.

[0092] Process 800 can be repeated multiple times. For example, process 800 can be performed between about 10 and about 1000 cycles or between about 50 and about 400 cycles.

[0093] To achieve the desired properties of the underlayer, the photoresist underlayer may desirably include from about 50 to about 55 atomic % oxygen and / or from about 10 to about 20 atomic % carbon.

[0094] Back again Figure 7 , method 700 may include an adhesion layer formation step (step 706), a densification step (step 708), and / or a MOR resist formation step (step 710). Step 706 may be the same as or similar to step 108. Step 708 may be the same as or similar to step 110. Step 710 may be the same as or similar to step 112.

[0095] To illustrate the advantages of forming an underlayer (e.g., bulk underlayer) with the desired oxygen and / or carbon content, Table 1 shows the post-development inspection (ADI) dose and line width roughness (LWR) / line edge roughness (LER) data for PEALD photoresist underlayers deposited under different conditions. SoG data are also listed for comparison. EVU lithography tests were performed using MOR resist. Underlayers deposited by Ar plasma showed high dose and poor LWR / LER. Some underlayers, such as those labeled A3, A4, A5, A8, A11, were obtained by H and O plasma deposition (Tables 1 and 2). Figure 9A and 9B ), which has lower dose than SoG and comparable LWR / LER. The lowest dose obtained was 60.5 mJ / cm 2 , achieving a dose reduction of ~5.5%. Therefore, according to an example of the present disclosure, a hydrogen-containing gas and / or an oxygen-containing gas is provided as a reactant during step 704. As a specific example, the reactant can be or include Ar, He, N2, O2, CO, CO2, N2O, C x H y (wherein x is between 1 and 8 and y is between 2 and 18), NH3, H2 or a mixture thereof plasma.

[0096] Table 1: Dose and LWR / LER data of PEALD EUV UL deposited under different conditions

[0097]

[0098] Figure 10 Figures a) and b) illustrate that composition can play a key role in dose reduction and lithographic performance. The dose decreases with increasing O%, likely due to the idea that O can generate more secondary electrons than Si and C. Secondary electrons can accelerate reactions in MOR resists. When O% > ~50%, the dose is less than that of SoG. For improved LWR, there is an optimal composition region, which for the illustrated example is O% between 50% and 55 atomic% and C% between 10% and 20 atomic%.

[0099] The exemplary photoresist underlayer shows lower dose and comparable lithographic performance to SoG can be achieved by adjusting the PEALD deposition conditions. The optimized sample is A4 deposited from H plasma. This sample shows a dose reduction of ~5.5%. It should be noted that if the MOR changes, the optimal deposition conditions can be changed. Composition appears to play an important role, but is not the only possible factor; other film properties may also affect the dose and lithographic performance of the PEALD photoresist underlayer. One of the advantages of PEALD EUV photoresist underlayers is that the composition and / or film properties can be easily adjusted by changing the deposition parameters. Therefore, for different kinds of MOR, the deposition conditions can be easily changed to adjust the composition and / or other properties of the UL to obtain the optimal UL.

[0100] Figure 11 An exemplary reactor system is shown that is suitable for use with method 100 or method 700. Reactor system 1100 can be used to perform one or more steps or sub-steps as described herein and / or form one or more structures or portions thereof as described herein.

[0101] Reactor system 1100 includes a pair of conductive plate electrodes 4, 2 that are parallel and face each other in the interior 11 (reaction zone) of reaction chamber 3. Plasma can be ignited in reaction chamber 3 by applying HRF power (e.g., 13.56 MHz or 27 MHz) from power supply 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 lower stage 2 (lower electrode), and the temperature of substrate 1 placed thereon can be maintained at a desired temperature. Electrode 4 can serve as a gas distribution device, such as a shower plate. Reactant gas, dilution gas (if any), precursor gas, etc. can be introduced into reaction chamber 3 through shower plate 4 using one or more of gas lines 20, gas line 21, and gas line 22, respectively. Although shown as having three gas lines, reactor system 1100 can include any suitable number of gas lines. Gas line 20 may be coupled to a silicon precursor source 29 , gas line 21 may be coupled to an inert gas source 27 , and gas line 22 may be coupled to another (eg, reactant) gas source 28 .

[0102] In the reaction chamber 3, a circular duct 13 with an exhaust line 7 is provided, through which the gas in the interior 11 of the reaction chamber 3 can be exhausted. In addition, the transfer area 5 provided below the reaction chamber 3 is provided with a sealing gas line 24 to introduce a sealing gas into the interior 11 of the reaction chamber 3 via the interior 16 (transfer zone) of the transfer area 5, wherein a separation plate 14 for separating the reaction zone and the transfer zone is provided (a gate valve is omitted in this figure, through which the wafer is transferred into and out of the transfer area 5). The transfer area is also provided with an exhaust line 6. In some embodiments, the deposition and densification steps are performed in the same reaction space, so that two or more (for example, all) steps (for example, deposition and adhesion layer) can be performed continuously without exposing the substrate to air or other oxygen-containing atmospheres.

[0103] In some embodiments, the continuous flow of inert gas or carrier gas to the reaction chamber 3 can be achieved using a flow-through system (FPS), wherein the carrier gas line is provided with a detour line having a precursor reservoir (bottle), and the main line and the detour line are switched, wherein when only the carrier gas is intended to be fed to the reaction chamber, the detour line is closed, and when both the carrier gas and the precursor gas are intended to be fed to the reaction chamber, the main line is closed, and the carrier gas flows through the detour line and out of the bottle together with the precursor gas. In this way, the carrier gas can flow continuously into the reaction chamber, and the precursor gas can be pulsed by switching between the main line and the detour line without substantially fluctuating the pressure of the reaction chamber.

[0104] Reactor system 1100 also includes one or more controllers 26, which are programmed or otherwise configured to perform one or more method steps as described herein. As those skilled in the art will appreciate, controller 26 is in communication with various power supplies, heating systems, pumps, robots, and gas flow controllers or valves of the reactor.

[0105] In some embodiments, a dual chamber reactor (two sections or compartments for processing wafers positioned close to each other) may be used, wherein reactant gases and noble gases may be supplied through common lines, while precursor gases are supplied through non-common lines.

[0106] The exemplary embodiments of the present disclosure described above do not limit the scope of the present 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, various modifications of the present disclosure, such as alternative useful combinations of the described elements, may become apparent to those skilled in the art from the description. Such modifications and embodiments are also intended to fall within the scope of the appended claims.

Claims

1. A method of forming a structure including a photoresist underlayer, the method comprising the steps of: providing a substrate comprising a carbon layer within a reaction chamber; Using a first cycle process, passivating a surface of the carbon layer to form a passivated surface; as well as Using the second cycle process, a lower layer of bulk photoresist is formed covering the passivated surface. During the first cycle, no oxidant is supplied to the reaction chamber.

2. The method according to claim 1, wherein The first cycle process includes: providing an inert gas to the reaction chamber; pulsing the precursor into the reaction chamber; and Plasma power is pulsed to the reaction chamber to form a plasma using the inert gas.

3. The method according to claim 2, wherein: The inert gas includes one or more of argon, helium, neon, krypton, xenon, ammonia, hydrazine or hydrogen.

4. The method of claim 2, further comprising purging a reaction chamber after pulsing the precursor and before pulsing the plasma power.

5. The method according to claim 4, wherein The plasma is ignited after a step of purging the reaction chamber.

6. The method according to claim 2, wherein: The precursor includes a silicon precursor.

7. The method according to claim 6, wherein: The silicon precursor contains oxygen.

8. The method according to claim 1, wherein The second cycle process includes: providing reactants to the reaction chamber; pulsing the precursor into the reaction chamber; and Plasma power is pulsed to the reaction chamber to form a plasma with the reactants.

9. The method according to claim 8, wherein The reactant comprises oxygen.

10. The method according to claim 1, wherein The first cycling process is performed for between about 50 cycles and about 80 cycles or between about 60 cycles and about 70 cycles.

11. A method of forming a structure including a photoresist underlayer, the method comprising the steps of: providing a substrate within the reaction chamber; forming a silicon oxycarbide underlayer overlying the substrate using a cyclic process; as well as forming a metal oxide resist layer covering the underlying layer, The silicon oxycarbide lower layer contains about 50 to about 55 atomic % of oxygen.

12. The method according to claim 11, wherein The silicon oxycarbide underlayer includes about 10 to about 20 atomic % carbon.

13. The method according to claim 11, wherein The cycle process includes: providing reactants to the reaction chamber; pulsing the precursor into the reaction chamber; and Plasma power is pulsed to the reaction chamber to form a plasma with the reactants.

14. The method according to claim 13, wherein The reactants include a hydrogen-containing gas.

15. The method according to claim 13, wherein The reactants include an oxygen-containing gas.

16. The method according to claim 13, wherein The precursor comprises one or more silicon precursors selected from the group consisting of: (i) ， wherein n is 1 or 2, and each R is independently selected from C1-C2 alkyl; (ii) , wherein n is 1 or 2, and each of R1 and R2 is independently selected from a C1-C2 alkyl or alkene functional group; (iii) , wherein n is 1 or 2, and each of R1 and R2 is independently selected from a C1-C2 alkyl or alkene functional group; or (iv) 。 17. The method according to claim 13, wherein: The chemical formula of the precursor consists of Si, C, H and O.

18. The method of claim 11, further comprising the step of densifying the silicon oxycarbide lower layer.

19. The method of claim 11, further comprising passivating a surface of the substrate.

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