Underlayer for ultraviolet (UV) polymeric resist

Abstract

Embodiments described herein relate to a method of modifying a resist layer that is provided over an underlayer. In an embodiment, the method includes exposing a portion of the resist layer and the underlayer to extreme ultraviolet (EUV) radiation to form an exposed region and an unexposed region, where the EUV radiation releases an acid from the exposed region of the underlayer. In an embodiment, the method further includes neutralizing photo decomposable quenchers (PDQs) in the exposed region of the resist layer with the acid.

Description

[0001] 44025605W001

[0002] UNDERLAYER FOR ULTRAVIOLET (UV) POLYMERIC RESIST

[0003] CROSS-REFERENCE TO RELATED APPLICATIONS

[0004] This application claims the benefit of U.S. Provisional Application No. 63 / 748,903, filed on January 23, 2025, the entire contents of which are hereby incorporated by reference herein.

[0005] FIELD

[0006] Embodiments relate to the field of semiconductor manufacturing and, in particular, an underlayer to improve patterning performance of an extreme ultraviolet (EUV) resist.

[0007] DESCRIPTION OF RELATED ART

[0008] Extreme ultraviolet (EUV) photoresists allow for the continued scaling to smaller features that are patterned on a semiconductor substrate. In an EUV lithography process, EUV radiation is selectively applied to regions of the photoresist layer in order to generate a solubility switch that enables the formation of a latent image within the photoresist layer. The latent image corresponds to the portions of the photoresist layer that have undergone the solubility switch as a result of a chemical reaction that is induced by the EUV exposure. After the latent image is produced within the photoresist layer, a developing process may be used in order to generate a pattern in the photoresist layer.

[0009] Typically, EUV compatible resists suffer from poor sensitivity. That is, a large dose is needed in order to provide the necessary solubility switch in order to provide adequate pattern formation (e.g., with suitable line edge roughness (LER), line width roughness (LWR), critical dimension uniformity (CDU), and / or the like). The larger dose increases the exposure time, which may be a bottleneck in the EUV lithography process.

[0010] SUMMARY

[0011] Embodiments described herein relate to a method of modifying a resist layer that is provided over an underlayer. In an embodiment, the method includes exposing a portion of the resist layer and the underlayer to extreme ultraviolet (EUV) radiation to form an exposed region and an unexposed region, where the EUV radiation releases an acid from the exposed region of the underlayer. In an embodiment, the method further includes neutralizing photo decomposable quenchers (PDQs) in the exposed region of the resist layer with the acid.

[0012] Embodiments described herein relate to a method of forming a functionalized underlayer for extreme ultraviolet (EUV) lithography. In an embodiment, the method includes depositing the underlayer over a substrate, where the underlayer includes carbon and one or more of fluorine,44025605W001

[0013] hydrogen, nitrogen, or oxygen, and generating -OH surface groups on a surface of the underlayer. In an embodiment, the method further includes functionalizing the -OH surface groups with an acid.

[0014] Embodiments described herein relate to an apparatus that includes a polymeric film, where the polymeric film includes carbon and one or more of fluorine, hydrogen, nitrogen, or oxygen. In an embodiment, the apparatus further includes a surface functionalization on a surface of the polymeric film. In an embodiment, the surface functionalization includes a linking molecule coupled to the surface of the polymeric film, a radiation sensitive unit coupled to the linking molecule, and an acid coupled to the radiation sensitive unit.

[0015] BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figures 1 A is a diagram of a deprotection reaction that makes a resist layer soluble through acid catalysis, in accordance with an embodiment.

[0017] Figure IB is a pictorial representation of a photoacid generator (PAG) that is exposed to extreme ultraviolet (EUV) radiation to release the acid, in accordance with an embodiment.

[0018] Figure 1C is a pictorial representation of a photo decomposable quencher (PDQ) that is neutralized through exposure to EUV radiation, in accordance with an embodiment.

[0019] Figures 2A - 2C are cross-sectional pictorial representations of a lithography process that illustrates limitations of the use of PDQs in the resist layer, in accordance with an embodiment. Figures 3A - 3C are cross-sectional pictorial representations of a lithography process that comprises an underlayer that releases acid to quench residual PDQs in the exposed region to improve lithography properties, in accordance with an embodiment.

[0020] Figures 4A and 4B depict a process for releasing an acid from an underlayer with a radiation exposure process, in accordance with an embodiment.

[0021] Figures 5A - 5E depict a series of chemical structures that may be used as the acid that is released from the underlayer, in accordance with an embodiment.

[0022] Figures 6A - 6G depict a series of chemical structure that may be used as the linking molecule between the acid and the underlayer, in accordance with an embodiment.

[0023] Figures 7A - 7C are cross-sectional illustrations that show a functionalization process of an underlayer, in accordance with an embodiment.

[0024] Figure 8 is a flow diagram that depicts a process for forming and patterning a resist layer, in accordance with an embodiment.

[0025] Figure 9 illustrates a block diagram of an exemplary computer system that may be used in conjunction with a processing tool, in accordance with an embodiment.44025605W001

[0026] DETAILED DESCRIPTION

[0027] Embodiments described herein include an underlayer to improve patterning performance of an extreme ultraviolet (EUV) resist. In the following description numerous specific details are set forth in order to provide a thorough understanding of embodiments. It will be apparent to one skilled in the art that embodiments may be practiced without these specific details. In other instances, well-known aspects are not described in detail in order to not unnecessarily obscure embodiments. Furthermore, it is to be understood that the various embodiments shown in the accompanying drawings are illustrative representations and are not necessarily drawn to scale. Various embodiments or aspects of the disclosure are described herein. In some implementations, the different embodiments are practiced separately. However, embodiments are not limited to embodiments being practiced in isolation. For example, two or more different embodiments can be combined together in order to be practiced as a single device, process, structure, or the like. The entirety of various embodiments can be combined together in some instances. In other instances, portions of a first embodiment can be combined with portions of one or more different embodiments. For example, a portion of a first embodiment can be combined with a portion of a second embodiment, or a portion of a first embodiment can be combined with a portion of a second embodiment and a portion of a third embodiment.

[0028] The embodiments illustrated and discussed in relation to the figures included herein are provided for the purpose of explaining some of the basic principles of the disclosure. However, the scope of this disclosure covers all related, potential, and / or possible, embodiments, even those differing from the idealized and / or illustrative examples presented. This disclosure covers even those embodiments which incorporate and / or utilize modern, future, and / or as of the time of this writing unknown, components, devices, systems, etc., as replacements for the functionally equivalent, analogous, and / or similar, components, devices, systems, etc., used in the embodiments illustrated and / or discussed herein for the purpose of explanation, illustration, and example.

[0029] As noted above, resists used in extreme ultraviolet (EUV) lithography often suffer from low sensitivity to the EUV radiation. This requires large doses to be used in order to provide the desired resist pattern properties (e.g., line edge roughness (LER), line width roughness (LWR), critical dimension CD uniformity (CDU), etc.). Typically, a large dose-to-size (DtS) is used to achieve the desired patterning results. This can lead to long exposure times, which makes the EUV radiation exposure process a bottleneck in the lithography process.

[0030] In chemically amplified resists (CARs), acids are released when photoacid generators (PAGs) are exposed to EUV radiation. The acids drive a solubility and / or polarity switch that renders the exposed region soluble to a developer. An example of the chemical deprotection is shown in44025605W001

[0031] Figure 1A. The insoluble protected polymer 102 reacts with an acid (e.g., to provide H+protons) in order to form a soluble deprotected polymer 103. Figure IB shows a pictorial representation of a PAG 110 that is exposed to EUV radiation. The PAG 110 may be a neutral species before exposure. The PAG may comprise an acid 112 and a counterion 111. After exposure to EUV radiation, the acid 112 is released and the counterion 111 becomes a neutral spectator molecule 113.

[0032] In some resists, photo decomposable quenchers (PDQs) may be used to neutralize acids outside of the exposed region of the resist layer. This prevents the acid 112 that diffuses into unexposed regions of the resist from initiating unwanted deprotection reactions in portions of the resist layer that are not intended to be rendered soluble. Figure 1C is a pictorial representation of a PDQ 115. The PDQ 115 is neutralized by EUV radiation and converts to a decomposed quencher that is a neutral spectator molecule 116.

[0033] Referring now to Figures 2A - 2C, a series of cross-sectional pictorial representations of a resist layer 220 that is exposed with EUV radiation is shown, in accordance with an embodiment. As shown in Figure 2 A, PAGs 210 with an acid 212 and a counterion 211 and PDQs 215 are distributed throughout the resist layer 220. As shown in Figure 2B, the resist layer 220 is selectively exposed with radiation 207 (e.g., EUV radiation 207) to form an exposed region 222. In an embodiment, the exposure releases the acids 212 from the PAGs 210. In some embodiments, some of the PDQs 215 may fail to be neutralized by the radiation 207.

[0034] Referring now to Figure 2C, a post exposure bake may be used to drive the deprotection reaction (as indicated by the change in shading of the resist layer 220). In an embodiment, some of the acid 212 is neutralized by residual PDQs 215 in the exposed region 222. As such, insoluble regions 217 may remain within the exposed region 222. This leads to incomplete development and can lead to poor patterning properties.

[0035] Accordingly, embodiments disclosed herein include an underlayer that is able to participate in the chemical conversion process of the resist layer. The underlayer may be photosensitive layer. Upon exposure to EUV radiation, the underlayer releases an acid that is able to diffuse into the overlying resist material. The diffused acid from the underlayer can be used to neutralize any remaining PDQs within the exposed region. Neutralization of the PDQs enables a more complete reaction of the PAGs within the resist layer to drive the polarity and / or solubility switch. This reduces the necessary dose to size needed to print desired feature sizes without an LWR tradeoff. In an embodiment, the underlayer may comprise a carbon based material with one or more of fluorine, hydrogen, nitrogen, or oxygen. In an embodiment, the underlayer may be functionalized with a weak acid that is attached to (or incorporated in) the underlayer. In some embodiments, the acid may be a weak acid, such as an organic acid or an inorganic acid. The44025605W001

[0036] acid may be fluorinated or non-fluorinated. In an embodiment, the acid may be attached to the underlayer through a linking molecule, such as an ester, a peroxide, an amide, an ozonide, a hydroperoxide, or the like. The acid may be coupled to the linking molecule by a photosensitive unit, such as o-nitrobenzene, a fluoro alcohol, or the like.

[0037] Referring now to Figures 3A - 3C, a series of cross-sectional pictorial representations of an exposure process for a resist layer 320 and an underlayer 330 is shown, in accordance with an embodiment.

[0038] Referring now to Figure 3A, a cross-sectional pictorial representation of the resist layer 320 and an underlayer 330 is shown, in accordance with an embodiment. In an embodiment, the resist layer 320 may comprise a CAR material. For example, the resist layer 320 may include a polymeric resin that is insoluble to a developing chemistry, such as a polymeric resin similar to the protected polymer 102 shown in Figure 1 A, or any other suitable protected polymer. In an embodiment the resist layer 320 may further comprise PAGs 310 and PDQs 315. While shown schematically as blocks, it is to be appreciated that the PAGs 310 may comprise any suitable molecule that can generate an acid upon exposure to radiation (e.g., EUV radiation and / or deep ultraviolet (DUV) radiation). For example, the PAGs 310 may comprise an acid 312 and a counter ion 311. Similarly, the PDQs 315 may include any suitable molecule that can be used to neutralize acids.

[0039] In an embodiment, an underlayer 330 may be provided below the resist layer 320. The underlayer 330 may be a carbon based material. The underlayer 330 may further comprise one or more of fluorine, hydrogen, nitrogen, or oxygen. For example, the underlayer 330 may comprise a CFx material or a CHx material. That is, species with a C-F bond and / or species with a C-H bond may be present within the underlayer 330.

[0040] In an embodiment, the underlayer 330 may be functionalized. That is, the underlayer 330 may be designed to release an acid after exposure to EUV radiation and / or DUV radiation. In an embodiment, the acid may diffuse into the overlying resist layer 320 to neutralize PDQs 315. As noted above, neutralization of the PDQs 315 within the exposed regions enables a more complete reaction of PAGs 310 with resist resin for the polarity and / or solubility switch. This decreases the dose to size needed to print features with a desired size without any negative LWR tradeoffs.

[0041] In an embodiment, functionalization of the underlayer 330 may be designed to contain different acidic groups that are attached to the underlayer 330 through linking bonds, such as one or more of an ester, an ether, an amide, an ozonide, or a hydroperoxide, a peroxide, an anhydride bond, or the like. For example, the bond strength between the acid and the underlayer 330 may be tailored through control of concentrations of hydrogen and / or fluorine within the underlayer. In an44025605W001

[0042] embodiment, the functionalization of the underlayer 330 may be a surface functionalization. For example, -OH surface groups on a surface of the underlayer 330 may be used as sites for Unking acids with a thermal functionalization process or the like. Examples of various acids and linking groups that may be suitable for functionalizing the underlayer 330 are provided in greater detail herein with respect to Figures 5A - 5E (for linking groups) and Figures 6A - 6G (for the acids). In an embodiment, the underlayer 330 may be provided over a patterning stack and a substrate (not shown). In an embodiment, the patterning stack may include one or more layers suitable for transferring a pattern formed into the resist layer 320 and the underlayer 330 into the underlying substrate. For example, the patterning stack may comprise multiple layers, such as a silicon hardmask layer, a carbon hardmask layer, an antireflective coating, and / or the like. In some embodiments, the patterning stack may comprise underlayer (not individually shown). In an embodiment, the underlayer 330 may be deposited over the patterning stack with a dry deposition process (e.g., chemical vapor deposition (CVD), atomic layer deposition (ALD), or the like). In an embodiment, the resist layer 320 may be deposited over the underlayer 330 with a wet process (e.g., a spin coating process) or a dry deposition process.

[0043] Referring now to Figure 3B, a cross-sectional pictorial representation of the resist layer 320 during a radiation exposure process is shown, in accordance with an embodiment. In an embodiment, the resist layer 320 is selectively exposed with radiation 307 (e.g., EUV radiation 307 and / or DUV radiation 307) to form an exposed region 322. The radiation 307 may be selectively applied to the resist layer 320 through a mask, a reticle, or the like. In other embodiments, the radiation 307 may be applied to the resist layer 320.

[0044] In an embodiment, the exposure releases the acids 312 from the PAGs 310 within the exposed region 322. The acids 312 are now free to react with the protected polymer resin to form a deprotected polymer that is soluble in a developer solution. Ideally, the radiation 307 exposure will neutralize all of the PDQs 315 within the exposed region 322. However, in some instances a residual amount of the PDQs 315 may fail to be neutralized by the radiation 307. The presence of the active PDQs 315 in the exposed region 322 runs the risk of acid 312 being neutralized so that portions of the exposed region 322 fail to undergo the desired solubility switch (as shown in Figure 2C).

[0045] However, the underlayer 330 also participates in the lithography process to mitigate the presence of residual PDQs 315 within the exposed region 322. As noted above, the underlayer 330 is functionalized with a releasable acid. Upon exposure to the radiation 307, the acid 331 from the exposed region 322 of the underlayer 330 may be released. The acid 331 may diffuse into the overlying exposed region 322 of the resist layer 320. In an embodiment, the acid 312 from the PAGs 310 and the acid 331 from the underlayer 330 may be different acids. In some44025605W001

[0046] embodiments, the acid 312 may be a stronger acid than the acid 331. For example, the acid 331 may be a weak acid.

[0047] Referring now to Figure 3C, a cross-sectional pictorial representation of the resist layer 320 after the acid 312 has initiated a deprotection process is shown, in accordance with an embodiment. In an embodiment, the exposure process in Figure 3C may be followed by a bake or anneal that allows for improved diffusion to distribute acids 312 and 3 1 through the exposed region 322. In an embodiment, the bake or anneal may also provide thermal energy that improves the rate of the deprotection reaction that allows for the transition to a deprotected polymer that is dissolvable by a developer chemistry.

[0048] As shown, the acids 331 may also be used to neutralize residual PDQs 315 that are present within the exposed region 322 of the resist layer 320. As shown, neutralized PDQs 318 have an acid 331 that is coupled to the PDQ 315. Accordingly, the residual PDQs 315 do not occupy available acids 312 used for the deprotection reaction. This enables a more complete reaction of PAGs 310 with the resist resin for the polarity and / or solubility switch, while also decreasing the dose to size needed to print features with a desired size without any negative LWR tradeoffs. Referring now to Figures 4A and 4B, a schematic illustration of an underlayer 430 that is functionalized (Figure 4A), and a schematic illustration of the underlayer 430 after radiation exposure (Figure 4B) are shown, in accordance with an embodiment. Referring now to Figure 4A, a cross-sectional schematic of the underlayer 430 is shown, in accordance with an embodiment. In an embodiment, the underlayer 430 may be similar to the underlayer 330 described in greater detail herein. For example, the underlayer 430 may comprise a carbon-based polymeric material. The underlayer 430 may be fluorinated in some embodiments. For example, the underlayer 430 may comprise C-F bonds.

[0049] In an embodiment, the underlayer 430 may have a surface functionalization 435. The surface functionalization 435 may include a linking molecule 437 (represented as an “A”) that is bonded 436 to the underlayer 430, and an acid 439 (represented as a “B”) that is linked to the linking molecule 437 by a radiation sensitive unit 438. In an embodiment, the radiation sensitive unit 438 may be a molecule that is configured to be severed to release the acid 439 so that the acid 439 may continue to diffuse into the overlying resist layer (not shown in Figure 4A). In an embodiment, the radiation sensitive unit 438 may comprise o-nitrobenzene, fluoro alcohol, or the like. The surface functionalization 435 may be applied to the underlayer 430 with any suitable process, such as those described in greater detail herein.

[0050] Referring now to Figure 4B, a schematic illustration of an underlayer 430 after exposure to radiation is shown, in accordance with an embodiment. As shown, the radiation sensitive unit 438 releases the acid 439. The acid 439 can then diffuse up into the overlying resist layer (not44025605W001

[0051] shown) so that the acid 439 can participate in the deprotection reaction and / or neutralize any residual PDQs within the exposed region of the resist layer. Since the acid 439 is only released in the exposed regions, the unexposed regions of the resist layer do not have additional acids added. In an embodiment, the linking molecule 437 may have a general formula that is shown in Figure 5A. Figure 5B shows Ri and R2 as comprising hydrogen, Figure 5C shows Ri and R2 as comprising fluorine, and Figure 5D shows Ri and R2 as comprising a trifluoromethyl group. In Figure 5E, the linking molecule may comprise a nitro benzene. In some embodiments, the R3 group of the linking molecule 437 may comprise any suitable linking group compatible with the underlayer 430 network. For example, the R group may comprise an ester, an ether, a peroxide, an amide, an ozonide, a hydroperoxide, an anhydride, or the like. In an embodiment, the acid 439 may have the general formula shown in Figure 6A. Figures 6B - 6G provide additional examples of acids 439 that may be used in the surface functionalization. In some embodiments, the acid 439 may comprise any suitable weak acid, such as an organic acid, an inorganic acid, and the acid 439 may comprise fluorinated and / or non-fluorinated moieties.

[0052] Embodiments disclosed herein may functionalize the underlayer with any number of different processes. In one embodiment, the underlayer may be designed to contain different acidic groups similar to any of those described in greater detail herein. In an embodiment, the acidic groups may be attached to the film through linking molecules, such as any of those described in greater detail herein. In some embodiments the bond strength of the acid to the linking molecule may be tailored with control of the concentrations of one or both of the hydrogen and / or fluorine within the underlayer.

[0053] In other embodiments, the surface functionalization may be obtained through a plasma process to form -OH surface groups followed by a thermal functionalization process or the like. An example of such a process is shown in Figures 7 A - 7C.

[0054] Referring now to Figure 7A, a cross-sectional illustration of a device with a substrate 701 and an underlayer 730 is shown, in accordance with an embodiment. In an embodiment, the underlayer 730 may be deposited over the substrate 701 with a dry deposition process. For example, the underlayer 730 may be deposited with a low power plasma deposition process. In some embodiments, the plasma deposition process may be a pulsed process. The plasma may include any type of plasma, such as a charge couple plasma (CCP) or an inductively coupled plasma (ICP). In some embodiments, the plasma may be a remote plasma. In yet another embodiment, the underlayer 730 may be formed with a spin-coating process. In an embodiment, the underlayer 730 may be a carbon-based layer with one or more of hydrogen, fluorine, nitrogen, or oxygen. For example, the underlayer 730 may comprise CFx and / or CHx bonds.

[0055] Referring now to Figure 7B, a cross-sectional illustration of the underlayer 730 after a plasma44025605W001

[0056] treatment process is used to form an oxygen functionalized surface 734 that comprises -OH groups at the surface of the underlayer 730 is shown, in accordance with an embodiment. The plasma treatment may be an oxygen based plasma in order to form the -OH groups. Other embodiments may include the use of a thermal oxygen treatment of the surface. For example, the underlayer 730 may be exposed to ozone at an elevated temperature to form the oxygen functionalized surface 734. While oxygen based treatments are described with respect to Figure 7B, other embodiments may include depositing the underlayer with an alcohol containing precursor. The use of such an alcohol containing precursor may enable a more integrated process in order to form the -OH groups at the surface of the underlayer 730.

[0057] Referring now to Figure 7C, a cross-sectional illustration of the underlayer 730 that is surface functionalized 735 with an acid is shown, in accordance with an embodiment. In an embodiment, the functionalization may be a thermal functionalization. For example, the underlayer 730 may be exposed to an acidic gas environment while held at an elevated temperature (e.g., at a temperature at or above approximately 100°C). In the illustrated embodiment, the acid shown in Figure 7C is a trifluoroacetic acid. Though, it is to be appreciated that any suitable weak acid such as those described in greater detail herein may be used in accordance with various embodiments.

[0058] Referring now to Figure 8, a flow diagram of a process 870 for forming and patterning a resist layer is shown, in accordance with an embodiment. In an embodiment, the process 870 may comprise operations, materials, chemical reactions, and / or the like that are similar to corresponding descriptions described in greater detail herein.

[0059] In an embodiment, the process 870 may begin with operation 871, which comprises depositing an underlayer over a substrate. In an embodiment, the underlayer may comprise a carbon-based material that includes fluorine. The underlayer may be deposited with a plasma deposition process, such as the process described above with respect to Figure 7A. For example, a low power plasma process may be used in some embodiments. In other embodiments, the underlayer may be deposited with a spin coating process.

[0060] In an embodiment, the process 870 may continue with operation 872, which comprises functionalizing a surface of the underlayer with a first acid. In an embodiment, the functionalization of the surface of the underlayer may include the formation of -OH groups at a surface of the underlayer. In an embodiment, the -OH groups may be formed through exposure of the underlayer to an oxygen containing plasma, through a thermal oxygen treatment (e.g., a thermal treatment in an ozone environment), or through integration of alcohol precursors into the deposition process used to form the underlayer in operation 871.

[0061] In an embodiment, the first acid may be attached to the -OH groups through a thermal44025605W001

[0062] functionalization process similar to the process shown in Figure 7C. In an embodiment, the thermal functionalization may include a temperature of approximately 100°C or higher during the exposure to the acid. The first acid may be similar to any of the acids coupled to the underlayers described in greater detail herein. For example, the first acid may be a weak acid, such as an organic acid, an inorganic acid, an acid with fluorine moieties or an acid without fluorine moieties.

[0063] In an embodiment, the process 870 may continue with operation 873, which comprises forming a resist layer over the underlayer. In an embodiment, the resist layer is a CAR material. For example, the resist layer may comprise a resin that comprises a protected insoluble polymer. In order to provide a solubility switch, the resist layer may comprise PAGs that release acid upon exposure to EUV radiation and / or DUV radiation. In an embodiment, the resist layer may also comprise PDQs in order to improve the patterning performance of the resist layer. The resist layer may be deposited with any suitable process. In some embodiments, the resist layer is deposited with a spin coating process, a dry deposition process, or any other suitable process. In an embodiment, the process 870 may continue with operation 874, which comprises exposing the resist layer and the underlayer to radiation (e.g., EUV radiation and / or DUV radiation) to form an exposed region and an unexposed region. In an embodiment, the radiation exposure results in the release of a second acid from the PAGs in the resist layer. Additionally, the first acid may be released from the underlayer in response to the radiation exposure.

[0064] In an embodiment, the released first acid and second acid may diffuse within the exposed region of the resist layer in order to drive a deprotection reaction that converts the resin in the exposed regions into a soluble deprotected polymer in accordance with a chemical reaction that may be similar to the chemical reaction shown in Figure 1 A. In some embodiments, a bake or an anneal may also be implemented in order to drive more diffusion of the first acid and the second acid, as well as providing more energy to initiate the deprotection reaction.

[0065] In an embodiment, the radiation exposure may also neutralize some of the PDQs within the exposed region of the resist layer. However some of the PDQs may persist within the exposed region. Accordingly, operation 875 may continue with neutralizing the residual PDQs within the exposed region with the first acid and / or the second acid. Neutralization of the PDQs within the exposed regions enables a more complete reaction of PAGs with the resist resin for the polarity and / or solubility switch. This decreases the dose to size needed to print features with a desired size without any negative LWR tradeoffs.

[0066] After the resist layer is exposed and the exposed region has undergone the polarity and / or solubility switch, the resist layer may be developed. The developing process may include exposing the resist layer to a developing solution that removes the exposed region of the resist44025605W001

[0067] layer. The pattern formed in the resist layer may then be transferred into underlying layers, such as the underlayer and the substrate, through one or more etching processes.

[0068] Referring now to Figure 9, a block diagram of an exemplary computer system 900 of a processing tool is illustrated in accordance with an embodiment. In an embodiment, computer system 900 is coupled to and controls processing in the processing tool. Computer system 900 may be connected (e.g., networked) to other machines in a Local Area Network (LAN), an intranet, an extranet, or the Internet. Computer system 900 may operate in the capacity of a server or a client machine in a client-server network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. Computer system 900 may be a personal computer (PC), a tablet PC, a set-top box (STB), a Personal Digital Assistant (PDA), a cellular telephone, a web appliance, a server, a network router, switch or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that machine. Further, while only a single machine is illustrated for computer system 900, the tenu “machine” shall also be taken to include any collection of machines (e.g., computers) that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies described herein.

[0069] Computer system 900 may include a computer program product, or software 922, having a non-transitory machine-readable medium having stored thereon instructions, which may be used to program computer system 900 (or other electronic devices) to perform a process according to embodiments. A machine-readable medium includes any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer). For example, a machine-readable (e.g., computer-readable) medium includes a machine (e.g., a computer) readable storage medium (e.g., read only memory (“ROM”), random access memory (“RAM”), magnetic disk storage media, optical storage media, flash memory devices, etc.), a machine (e.g., computer) readable transmission medium (electrical, optical, acoustical or other form of propagated signals (e.g., infrared signals, digital signals, etc.)), etc.

[0070] In an embodiment, computer system 900 includes a system processor 902, a main memory 904 (e.g., read-only memory (ROM), flash memory, dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM) or Rambus DRAM (RDRAM), etc.), a static memory 906 (e.g., flash memory, static random access memory (SRAM), etc.), and a secondary memory 918 (e.g., a data storage device), which communicate with each other via a bus 930.

[0071] System processor 902 represents one or more general-purpose processing devices such as a microsystem processor, central processing unit, or the like. More particularly, the system processor may be a complex instruction set computing (CISC) microsystem processor, reduced instruction set computing (RISC) microsystem processor, very long instruction word (VLIW)44025605W001

[0072] microsystem processor, a system processor implementing other instruction sets, or system processors implementing a combination of instruction sets. System processor 902 may also be one or more special-purpose processing devices such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal system processor (DSP), network system processor, or the like. System processor 902 is configured to execute the processing logic 926 for performing the operations described herein.

[0073] The computer system 900 may further include a system network interface device 908 for communicating with other devices or machines. The computer system 900 may also include a video display unit 910 (e.g., a liquid crystal display (LCD), a light emitting diode display (LED), or a cathode ray tube (CRT)), an alphanumeric input device 912 (e.g., a keyboard), a cursor control device 914 (e.g., a mouse), and a signal generation device 916 (e.g., a speaker).

[0074] The secondary memory 918 may include a machine-accessible storage medium 931 (or more specifically a computer-readable storage medium) on which is stored one or more sets of instructions (e.g., software 922) embodying any one or more of the methodologies or functions described herein. The software 922 may also reside, completely or at least partially, within the main memory 904 and / or within the system processor 902 during execution thereof by the computer system 900, the main memory 904 and the system processor 902 also constituting machine-readable storage media. The software 922 may further be transmitted or received over a network 961 via the system network interface device 908. In an embodiment, the network interface device 908 may operate using RF coupling, optical coupling, acoustic coupling, or inductive coupling.

[0075] While the machine-accessible storage medium 931 is shown in an exemplary embodiment to be a single medium, the term “machine-readable storage medium” should be taken to include a single medium or multiple media (e.g., a centralized or distributed database, and / or associated caches and servers) that store the one or more sets of instructions. The term “machine-readable storage medium” shall also be taken to include any medium that is capable of storing or encoding a set of instructions for execution by the machine and that cause the machine to perform any one or more of the methodologies. The term “machine-readable storage medium” shall accordingly be taken to include, but not be limited to, solid-state memories, and optical and magnetic media.

[0076] In the foregoing specification, specific exemplary embodiments have been described. It will be evident that various modifications may be made thereto without departing from the scope of the following claims. The specification and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense.

Claims

44025605W001CLAIMSWhat is claimed is:

1. A method of modifying a resist layer that is provided over an underlayer, comprising:exposing a portion of the resist layer and the underlayer to extreme ultraviolet (EUV) radiation to form an exposed region and an unexposed region, wherein the EUV radiation releases an acid from the exposed region of the underlayer; andneutralizing photo decomposable quenchers (PDQs) in the exposed region of the resist layer with the acid.

2. The method of claim 1, wherein the underlayer comprises carbon and fluorine.

3. The method of claim 1 , wherein the acid is a surface functionalization on the underlayer that is coupled to the underlayer by a linking molecule.

4. The method of claim 3, wherein the linking molecule is one or more of an ether, an amide, a peroxide, an anhydride, an ozonide, or a hydroperoxide.

5. The method of claim 4, wherein the acid is coupled to the linking molecule by a radiation sensitive unit.

6. The method of claim 5, wherein the radiation sensitive unit comprises one or more of o- nitrobenzene or fluoro alcohol.

7. The method of claim 1 , wherein the acid is an organic acid or an inorganic acid.

8. The method of claim 1, wherein the EUV radiation releases a second acid from photoacid generators (PAGs) in the exposed region, and wherein the PDQs in the exposed region are neutralized by the acid and the second acid.

9. A non-transitory computer readable medium comprising instructions that, when executed by at least one processor, cause a processing tool to perform the method of claim 1.

10. A method of forming a functionalized underlayer for extreme ultraviolet (EUV) lithography, the method comprising:depositing the underlayer over a substrate, wherein the underlayer comprises carbon and one or more of fluorine, hydrogen, nitrogen, or oxygen;generating -OH surface groups on a surface of the underlayer; andfunctionalizing the -OH surface groups with an acid.

11. The method of claim 10, wherein depositing the underlayer over the substrate comprises a plasma deposition process.

12. The method of claim 11, wherein the plasma deposition process further comprises a pulsed plasma deposition process.

13. The method of claim 10, wherein generating the -OH surface groups on the surface of the44025605W001underlayer comprises exposing the underlayer to a plasma comprising oxygen.

14. The method of claim 10, wherein functionalizing the -OH surface groups with the acid comprises a thermal functionalization in an acidic environment at a temperature of 100°C or higher.

15. The method of claim 10, wherein the acid is an organic acid.

16. The method of claim 10, wherein the acid is an inorganic acid.

17. The method of claim 10, wherein the acid comprises fluorinated moieties.

18. An apparatus, comprising:a polymeric film, wherein the polymeric film comprises carbon and one or more of fluorine, hydrogen, nitrogen, or oxygen; anda surface functionalization on a surface of the polymeric film, wherein the surface functionalization comprises:a linking molecule coupled to the surface of the polymeric film;a radiation sensitive unit coupled to the linking molecule; andan acid coupled to the radiation sensitive unit.

19. The apparatus of claim 18, wherein the acid comprises an organic acid or an inorganic acid, and wherein the acid comprises fluorinated moieties or non-fluorinated moieties.

20. The apparatus of claim 18, wherein the linking molecule comprises one or more of an ester, a peroxide, an amide, an ozonide, or a hydroperoxide.

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