Methods for extreme ultraviolet (EUV) resist patterning development

Abstract

A method is provided for patterning extreme ultraviolet (EUV) (or shorter wavelength) photoresists, such as metal oxide photoresists. [Solution] A patterning layer including a metal oxide photoresist is formed on one or more underlayers provided on a substrate, and portions of the patterning layer not covered by a mask are exposed to EUV light or shorter wavelength light. Subsequently, a repetitive dry process is performed to remove the portions of the patterning layer exposed to EUV light or shorter wavelength light (exposed portions) and develop the metal oxide photoresist pattern. The repetitive dry process generally includes multiple deposition and etching steps, where the deposition step selectively deposits a protective layer on the unexposed portions of the patterning layer by exposing the substrate to a first plasma, and the etching step selectively etches the exposed portions of the patterning layer by exposing the substrate to a second plasma.

Description

[Technical Field]

[0001] Incorporation by Reference This disclosure claims the benefit of U.S. Non-Provisional Patent Application No. 17 / 097,921, filed November 13, 2020, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] The present disclosure relates to processing substrates. In particular, the present disclosure provides novel systems and methods for patterning EUV (or shorter wavelength) photoresists.

[0003] To achieve reduced feature sizes, patterning using extreme ultraviolet (EUV) lithography has been implemented in processing systems. EUV lithography typically uses light with wavelengths of 6 to 16 nanometers (nm) or less. For example, EUV patterning techniques have been implemented in production for advanced semiconductor device manufacturing at the sub-7 nm node. While reduced feature sizes have been achieved, pattern performance challenges have arisen with EUV patterning.

[0004] Chemically amplified resists (CARs) have been used in EUV lithography to transfer patterns onto one or more underlying layers formed on a substrate. While such resists have good sensitivity, the resolution of CARs is more strongly affected by pattern collapse, which becomes increasingly important as feature sizes approach the nanometer scale. In addition, reducing the aspect ratio (film thickness / critical dimension) of CARs is challenging due to their high sensitivity to non-uniform distribution of components in the film. As a result, CARs tend to exhibit poor imaging performance.

[0005] Metal oxide photoresists have been used in negative-tone EUV lithography to transfer patterns onto one or more underlying layers formed on a substrate. Compared to CAR, metal oxide photoresists offer the advantage of very thin film thickness, minimizing the risk of pattern collapse. Conventional processes used to form metal oxide photoresists, which are promising alternatives to CAR, utilize wet processes for pattern development. For example, metal oxide photoresists can be developed using wet organic developers in negative-tone photoresist processes. While negative-tone photoresists can be suitable for patterning line / space features and blocks, negative-tone photoresists have been less satisfactory for patterning other features, such as holes or vias. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, there is a need for improved processes and methods for patterning metal oxide photoresists used in EUV (or shorter wavelength) lithography. [Means for solving the problem]

[0007] Provided herein are improved process flows and methods for patterning extreme ultraviolet (EUV) or shorter wavelength photoresists. More specifically, provided herein are improved process flows and methods for patterning metal oxide photoresists, which can be used in EUV (or shorter wavelength) photolithography to transfer patterns onto one or more underlying layers formed on a substrate. In the disclosed process flows and methods, a patterning layer comprising a metal oxide photoresist is formed on one or more underlying layers disposed on a substrate, and portions of the patterning layer not covered by a mask over the patterning layer are exposed to EUV or shorter wavelength light. The EUV or shorter wavelength exposure causes organic ligands to separate from metal oxide structures (e.g., cages or chains) in the exposed portions of the metal oxide photoresist, while leaving the unexposed portions of the metal oxide photoresist unchanged. After EUV or shorter wavelength exposure, a bake process is performed to release the free organic ligands from the exposed portions of the metal oxide photoresist, and a plasma process is used to remove (e.g., etch) the exposed portions, developing the metal oxide photoresist pattern.

[0008] The plasma processes described herein can develop metal oxide photoresist patterns using multiple deposition and etching steps. In some embodiments, a hydrocarbon- or fluorocarbon-based plasma can be used in the deposition step to selectively deposit a protective layer (or film) on the unexposed portions of the metal oxide photoresist. During the etching step, a hydrogen- or halogen-based plasma can be used to selectively convert the surface of the exposed portions of the metal oxide photoresist to a volatile material (e.g., a metal hydride, halide, or chloride), which can be removed, for example, by ion bombardment. The protective layer selectively deposited on the unexposed portions of the metal oxide photoresist protects the unexposed portions from erosion while the exposed portions of the metal oxide photoresist are selectively etched during the etching step. In some embodiments, the plasma development process described herein can be continued in an iterative manner, repeating the selective deposition and selective etching steps until the exposed portions of the metal oxide photoresist are completely removed.

[0009] According to one embodiment, a method for patterning a substrate is provided. In this embodiment, the method may include forming a patterning layer and one or more underlayers on a substrate, where the patterning layer comprises a metal oxide photoresist, and performing an extreme ultraviolet (EUV) or shorter wavelength lithography process, where portions of the patterning layer not covered by an overlying mask are exposed to EUV or shorter wavelength light. Additionally, the method may include performing repeated drying processes to remove portions of the patterning layer exposed to EUV or shorter wavelength light and develop the metal oxide photoresist pattern.

[0010] In some embodiments, the repeated dry process may include selectively depositing a protective layer on the unexposed portions of the patterned layer by exposing the substrate to a first plasma, selectively etching the exposed portions of the patterned layer by exposing the substrate to a second plasma, and repeating the selective deposition and selective etching until the exposed portions of the patterned layer are completely removed. The unexposed portions of the patterned layer are those portions that are covered by an overlying mask and are not exposed to EUV light or shorter wavelength light. In contrast, the exposed portions of the patterned layer are not covered by an overlying mask and are exposed to EUV light or shorter wavelength light.

[0011] The first and second plasmas can utilize a wide variety of precursor gases. In some embodiments, the first plasma can include a hydrocarbon or fluorocarbon-based precursor gas. In some embodiments, the second plasma can include a hydrogen- or halogen-containing precursor gas and an inert gas.

[0012] Each time a selective etching step is performed, a hydrogen or halogen-containing precursor gas converts the exposed surface portions of the patterned layer into volatile materials, and ions of an inert gas bombard the surface of the substrate to remove the volatile materials from the exposed portions. Each time a selective deposition step is performed, a new protective layer is deposited on the unexposed portions of the patterned layer.

[0013] According to another embodiment, another method of patterning a substrate is provided. This embodiment may include forming a patterning layer and one or more underlayers on a substrate, where the patterning layer includes a metal oxide photoresist, and exposing portions of the patterning layer not covered by a mask over the patterning layer to extreme ultraviolet (EUV) light or shorter wavelength light. Additionally, the method may include selectively depositing a protective layer on the unexposed portions of the patterning layer by exposing the substrate to a first plasma, selectively etching the exposed portions of the patterning layer by exposing the substrate to a second plasma, and repeating the selective deposition and selective etching steps until the exposed portions of the patterning layer are completely removed.

[0014] In some embodiments, the patterning layer may comprise a metal oxide material, the metal oxide material comprising clusters of metal oxide structures having chemically bonded organic ligands. In such embodiments, exposing portions of the patterning layer not covered by the patterned mask layer to EUV light or shorter wavelength light dissociates the organic ligands from the metal oxide structures while leaving the unexposed portions of the patterning layer unchanged. The method may further comprise performing a bake process after exposing portions of the patterning layer not covered by the patterned mask layer to EUV light or shorter wavelength light and before selectively depositing a protective layer on the unexposed portions of the patterning layer to release the organic ligands from the exposed portions of the patterning layer.

[0015] As described above, the first plasma and the second plasma can utilize a wide variety of precursor gases. In some embodiments, the first plasma can include a hydrocarbon or fluorocarbon precursor gas. For example, the first plasma can include CH4, CF8, CF6, or CH3F. In some embodiments, the second plasma can include a hydrogen- or halogen-containing precursor gas. For example, the second plasma can include CH4, CF4, CHF3, or BCl3. In some embodiments, the second plasma can further include an inert gas. For example, the second plasma can further include argon (Ar). When the second plasma contains a hydrogen- or halogen-containing precursor gas and an inert gas, the hydrogen- or halogen-containing precursor gas converts the exposed surface of the patterned layer into a volatile material, and the inert gas ions bombard the exposed surface and remove the volatile material.

[0016] In some embodiments, selectively depositing the protective layer on the unexposed portions of the patterned layer and selectively etching the exposed portions of the patterned layer are performed simultaneously in a plasma processing chamber using the same plasma precursor gases to generate the first and second plasmas. In such embodiments, for example, the first and second plasmas may each comprise a hydrocarbon precursor and an inert gas.

[0017] In other embodiments, the steps of selectively depositing the protective layer on the unexposed portions of the patterned layer and selectively etching the exposed portions of the patterned layer are separated within a plasma processing chamber such that the first and second plasmas are generated using different plasma precursor gases. In such embodiments, for example, the first plasma may include a hydrocarbon precursor and the second plasma may include a halocarbon precursor and an inert gas.

[0018] A more complete understanding of the present invention and its advantages can be obtained by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals indicate like features, and in which: It should be noted, however, that the accompanying drawings depict only exemplary embodiments of the disclosed concepts and are therefore not to be considered limiting in scope, as the disclosed concepts may also be susceptible to other equally effective embodiments. [Brief explanation of the drawings]

[0019] [Figures 1A-1F] An improved process flow for patterning a substrate, and more particularly for patterning extreme ultraviolet (EUV) photoresist, is presented. [Figure 2] FIG. 1 is a flow diagram illustrating one embodiment of a method for patterning a substrate. [Figure 3] FIG. 10 is a flow diagram illustrating another embodiment of a method for patterning a substrate. [Figure 4] FIG. 1 is a block diagram illustrating one embodiment of a plasma processing system that can be used to pattern a substrate using the techniques described herein. DETAILED DESCRIPTION OF THE INVENTION

[0020] Provided herein are improved process flows and methods for patterning extreme ultraviolet (EUV) (or shorter wavelength) photoresists. More specifically, provided herein are improved process flows and methods for patterning metal oxide photoresists, which can be used in EUV or shorter wavelength photolithography to transfer patterns onto one or more underlying layers formed on a substrate. The process flows and methods disclosed herein can be used with a wide variety of metal oxide materials, including, but not limited to, metal oxides containing tin (Sn), hafnium (Hf), and zirconium (Zr). While metal oxide materials containing Sn, Hf, or Zr are disclosed herein as examples, the process flows and methods disclosed herein are extendable to other metal oxide materials and metal-containing photoresists. As described herein, exemplary embodiments utilizing EUV wavelength light are discussed. However, the techniques utilized herein are not limited to EUV wavelengths. Furthermore, the techniques may be particularly advantageous for EUV or shorter wavelength light. Thus, although some examples herein are described with respect to EUV wavelengths, the techniques provided may also be applicable to EUV light or light of shorter wavelengths.

[0021] In the disclosed process flow and method, a patterning layer comprising a metal oxide photoresist is formed on one or more underlying layers disposed on a substrate, and portions of the patterning layer not protected by a mask between a light source and the patterning layer are exposed to EUV light. The EUV exposure causes organic ligands to separate from the metal oxide structures (e.g., cages or chains) in the exposed portions of the metal oxide photoresist, while leaving the unexposed portions of the metal oxide photoresist unchanged. After the EUV exposure, a bake process is performed to release the released organic ligands from the exposed portions of the metal oxide photoresist, and a plasma process is used to remove (e.g., etch) the exposed portions to develop the metal oxide photoresist pattern. In this manner, dry plasma development of the metal oxide photoresist is provided.

[0022] The plasma processes described herein can develop metal oxide photoresist patterns using multiple deposition and etching steps. In some embodiments, a hydrocarbon- or fluorocarbon-based plasma can be used in the deposition step to selectively deposit a protective layer (or film) on the unexposed portions of the metal oxide photoresist. During the etching step, a hydrogen- or halogen-based plasma can be used to selectively convert the surface of the exposed portions of the metal oxide photoresist to a volatile material (e.g., a metal hydride, halide, or chloride), which can be removed, for example, by ion bombardment. The protective layer selectively deposited on the unexposed portions of the metal oxide photoresist protects the unexposed portions from erosion while the exposed portions of the metal oxide photoresist are selectively etched during the etching step. In some embodiments, the plasma development process described herein can be continued in an iterative manner, repeating the selective deposition and selective etching steps until the exposed portions of the metal oxide photoresist are completely removed.

[0023] Accordingly, for advanced EUV patterning, a novel plasma development process for metal oxide photoresist is disclosed herein. The plasma development process enables selective deposition and selective etching at the molecular / atomic level with precise plasma process control. In addition to other plasma process parameters, plasma precursors are selected to selectively convert the surface of EUV-activated areas (i.e., exposed portions of the metal oxide photoresist) to more volatile materials (e.g., metal hydrides, halogens, or chlorides) in the selective etching step and to selectively deposit a protective layer on non-activated areas (i.e., unexposed portions of the metal oxide photoresist) in the selective deposition step. In some embodiments, the plasma treatment steps disclosed herein may be performed simultaneously in a plasma processing chamber using the same plasma precursor for both the deposition and etching steps. In other embodiments, the plasma treatment steps may be separated within a plasma processing chamber so that the deposition and etching steps can be performed using different plasma precursors.

[0024] 1A-1F illustrate one embodiment of an improved process flow for patterning EUV metal oxide photoresist in accordance with the techniques disclosed herein. It will be understood that the embodiment illustrated in Figures 1A-1F is merely exemplary, and that the techniques described herein may be applied to other process flows.

[0025] 1A, substrate 100 includes a patterning layer 108 formed over one or more underlying layers, such as a hard mask layer 106, a sacrificial carbon layer 104, and a base substrate 102. Base substrate 102 can be any substrate on which the use of patterned features is desired. For example, base substrate 102 can be a semiconductor substrate having one or more semiconductor processing layers formed thereon. In one embodiment, base substrate 102 can be a substrate that has undergone multiple semiconductor processing steps resulting in a wide variety of structures and layers, all of which are known in the substrate processing art.

[0026] The hard mask layer 106 and the sacrificial carbon layer 104 may be formed from any of a wide variety of materials known in the art. In one embodiment, the hard mask layer 106 may be a spin-on-glass (SOG) layer and the sacrificial carbon layer 104 may be a spin-on-carbon (SOC) layer. However, it should be understood that the underlayers described and illustrated are merely exemplary, and that more, fewer, or other underlayers may be utilized.

[0027] The patterned layer 108 shown in FIG. 1A can be formed from any of a wide variety of materials commonly used in EUV lithography. For example, the patterned layer 108 can be a metal oxide photoresist. In some embodiments, the patterned layer 108 can include a metal oxide material containing tin (Sn), hafnium (Hf), or zirconium (Zr). Other metal oxide materials can also be used to achieve the patterned layer 108. In some embodiments, a metal-containing non-oxide photoresist material can be used to achieve the patterned layer 108. The patterned layer 108 can generally be formed using any of a wide variety of deposition processes. In some embodiments, the patterned layer 108 can be formed using, for example, a spin-coating process. However, the techniques described herein are not limited to a method for forming the patterned layer 108.

[0028] In the exemplary embodiment shown in FIG. 1A, the patterned layer 108 may include a metal oxide material, which includes clusters of metal oxide structures (MOs) with chemically bonded organic ligands (L). As described in more detail below, the process flow shown in FIGS. 1B-1C involves exposing portions of the patterned layer 108 to extreme ultraviolet (EUV) light to dissociate or release the organic ligands (L) from the metal oxide structures (MOs), and performing a bake process to release the released ligands from the EUV-exposed portions of the patterned layer 108. Once the organic ligands are released, repeated drying processes are used to remove the EUV-exposed portions of the patterned layer 108 and develop the metal oxide photoresist pattern, as shown in FIGS. 1D-1F.

[0029] After the patterning layer 108 is formed in Figure 1A, a mask 110 is placed over the patterning layer 108 and an EUV lithography process is performed in Figure 1B. During the EUV lithography process shown in Figure 1B, exposed portions 114 of the patterning layer 108 (i.e., the portions of the patterning layer 108 not protected by the mask 110) are exposed to an EUV light source 112. As shown in Figure 1B, the EUV exposure causes the organic ligands (L) to separate from the metal oxide structures (MO) only in the exposed portions 114 of the patterning layer 108, while leaving the unexposed portions 116 of the patterning layer 108 unchanged.

[0030] After the EUV lithography step is performed in Figure 1B, a post-exposure bake (PEB) process is performed to release the released ligands from the exposed portions 114 of the patterning layer 108, leaving only dense metal oxide structures (MOs) in the exposed portions 114, as shown in Figure 1C. After the PEB process is performed, a dry process (e.g., a plasma development process) is used to remove the exposed portions 114 of the patterning layer 108 and develop the metal oxide photoresist pattern.

[0031] 1D-1F illustrate one embodiment of a plasma development process that can be used to develop a metal oxide photoresist pattern in accordance with the techniques described herein. As described in more detail below, the disclosed plasma development process can generally include multiple deposition and etching steps. In some embodiments, the plasma development process can begin by exposing the substrate 100 to a first plasma 118 to selectively deposit a protective layer 120 on the unexposed portions 116 of the patterned layer 108, as shown in FIG. 1D. After the protective layer 120 is formed on the unexposed portions 116, the substrate 100 is exposed to a second plasma 122 to selectively etch or remove the exposed portions 114 of the patterned layer 108, as shown in FIG. 1E. The protective layer 120 protects the unexposed portions 116 of the patterned layer 108 from erosion, while the exposed portions 114 of the patterned layer 108 are selectively etched and removed during the selective etching step. In some embodiments, the plasma development process shown in Figures 1D and 1E may be continued in an iterative manner by repeating the selective deposition and selective etching steps multiple times and / or until the exposed portions 114 of the patterned layer 108 are completely removed, as shown in Figure 1F.

[0032] A variety of plasma chemistries can be used in the selective deposition process shown in Figure ID. In some embodiments, the first plasma 118 can use hydrocarbon- or fluorocarbon-based precursor gas chemistries to selectively deposit the protective layer 120 on the unexposed portions 116 of the patterned layer 108. Examples of hydrocarbon- and fluorocarbon-based chemistries that can be used in the first plasma 118 include, but are not limited to, CH4, C4F8, C4F6, or CH3F. Other hydrocarbon- or fluorocarbon-based chemistries can also be used in the selective deposition process shown in Figure ID.

[0033] Various plasma chemistries can be used in the selective etching process shown in FIG. 1E. In some embodiments, the second plasma 122 can use hydrogen- or halogen-containing precursor gas chemistries to convert the surface of the exposed portion 114 into a volatile material (e.g., a metal hydride, halide, or chloride) and can use an inert gas (e.g., argon) to selectively etch or remove the volatilized surface via ion bombardment. Examples of hydrogen- or halogen-containing precursor gas chemistries that can be used in the second plasma 122 include, but are not limited to, hydrocarbon-based chemicals (e.g., CH), halocarbon-based chemicals (e.g., CF, CHF), and other halogen-based chemicals (e.g., BCl) commonly used in plasma etching. In some embodiments, a combination of a hydrocarbon precursor gas and an inert gas can be used to generate the second plasma 122. In other embodiments, the second plasma 122 can include a combination of a halocarbon, hydrogen, and an inert gas.

[0034] The hydrogen (or halogen) component contained in the second plasma 122 facilitates etching by converting the surface of the metal oxide material in the exposed portions 114 to volatile metal hydrides, halides, or chlorides, which, in one embodiment, are removed by ion bombardment. In some embodiments, the selective etching step shown in FIG. 1E can be performed as a single step by exposing the substrate 100 to a plasma containing a hydrogen (or halogen)-containing precursor gas and an inert gas (e.g., argon). In other embodiments, the selective etching step can be an iterative process in which the substrate 100 is exposed to a hydrogen (or halogen)-based plasma before being exposed to an argon plasma.

[0035] Although an exemplary embodiment is described herein with reference to argon (Ar), other inert gas ions can also be used to bombard the surface of the exposed portion 114 in the selective etching process shown in FIG. 1D . Exemplary inert gases include, but are not limited to, He, Ne, Kr, and other noble gases. Additionally, other gases can be utilized in combination with argon and / or noble gases. For example, the plasma is not limited to having only argon gas or noble gases, and other gases can be added to the plasma. For example, other inert gases, or other gases that are not inert gases, can be added to the process.

[0036] In some embodiments, the selective deposition and selective etching steps shown in Figures 1D and 1E may be performed simultaneously in a plasma processing chamber, or alternatively, may be separated into two plasma processing steps, separated, for example, by one or more purge steps. In one embodiment, the selective deposition and etching steps may be performed simultaneously in a plasma processing chamber using the same plasma precursor (e.g., CH4) for both the deposition and etching steps. In other embodiments, the selective deposition and etching steps may be separated in a plasma processing chamber so that different plasma precursors can be used in the deposition and etching steps. For example, the selective deposition and etching steps may be separated in a plasma processing chamber, such that the deposition step can use a hydrocarbon precursor (e.g., CH4), while the etching step uses hydrogen (H2), a halocarbon-based chemical (e.g., CF4 or CHF3), and a halogen-based chemical (e.g., BCl3).

[0037] The selective deposition and etching steps shown in FIGS. 1D and 1E may be performed as an iterative process, which is repeated multiple times until the exposed portions 114 of the patterning layer 108 are completely removed, as shown in FIG. 1F. Each time an etching step is performed, some or all of the protective layer 120 formed on the unexposed portions 116 may be removed along with the volatilized surfaces of the exposed portions 114. In one embodiment, a very thin protective layer may remain after each cycle. With each subsequent deposition step, a new protective layer 120 is formed on the top and side surfaces of the unexposed portions 116, as shown in FIG. 1F. To avoid etching the hard mask layer 106 underlying the patterning layer 108, the plasma chemistries used in the selective deposition and etching steps described herein may generally be selective to the hard mask layer 106.

[0038] Compared to conventional pattern development processes that use wet processes to develop negative metal oxide photoresists, the plasma development process shown in Figures 1D-1F uses an iterative dry process for pattern development of positive photoresists. Unlike negative photoresists, positive photoresists can be used for hole, block, and line / space patterning in narrow geometry processes. By utilizing an iterative dry process for pattern development, the plasma development process described herein provides atomic layer control of surface reactions, improving line edge roughness (LER) and critical dimension (CD) control compared to pattern development by conventional wet processes. The plasma development process described herein is also cleaner and more cost-effective than pattern development by conventional wet processes.

[0039] 2-3 illustrate an exemplary method of patterning a substrate using the plasma development process described herein. It will be understood that the embodiments of FIGS. 2-3 are merely exemplary, and that additional methods may utilize the techniques described herein. Furthermore, the described process steps are not intended to be exclusive, and additional steps may be added to the methods shown in FIGS. 2-3. Furthermore, the order of steps is not limited to the order shown in the figures, as different orders may occur and / or various steps may be performed in combination or simultaneously. Furthermore, while the methods of FIGS. 2-3 are described with respect to EUV light, it will be understood that EUV light or shorter wavelength light may be advantageous.

[0040] 2 illustrates one embodiment of a method 200 that can be used to pattern a substrate using the techniques disclosed herein. In some embodiments, method 200 can begin by forming a patterning layer and one or more underlayers on a substrate, where the patterning layer comprises a metal oxide photoresist (step 210). After the patterning layer is formed, method 200 performs an extreme ultraviolet (EUV) lithography step, in which portions of the patterning layer not covered by an overlying mask are exposed to EUV light (step 220). In step 230, method 200 performs an iterative drying process to remove portions of the patterning layer exposed to EUV light and develop the metal oxide photoresist pattern.

[0041] FIG. 3 illustrates another embodiment of a method 300 that can be used to pattern a substrate using the techniques disclosed herein. In some embodiments, method 300 can begin by forming a patterning layer and one or more underlayers on a substrate, where the patterning layer comprises a metal oxide photoresist (step 310). After the patterning layer is formed, method 300 exposes portions of the patterning layer that are not covered by a mask over the patterning layer to extreme ultraviolet (EUV) light (step 320). In step 330, method 300 selectively deposits a protective layer on the unexposed portions of the patterning layer by exposing the substrate to a first plasma. The unexposed portions of the patterning layer are covered by a mask and are not exposed to the EUV light source. In step 340, method 300 selectively etches the exposed portions of the patterning layer by exposing the substrate to a second plasma. In step 350, method 300 repeats the selective depositing and selective etching until the exposed portions of the patterning layer are completely removed.

[0042] 4 provides one exemplary embodiment of a plasma processing system 400 that may be used in connection with the disclosed technology and is provided for illustrative purposes only. While the plasma processing system 400 shown in FIG. 4 is a capacitively coupled plasma (CCP) processing apparatus, those skilled in the art will understand that the technology described herein may be implemented in an inductively coupled plasma processing (ICP) apparatus, a microwave plasma processing apparatus, a radial line slot antenna (RLSA™) microwave plasma processing apparatus, an electron cyclotron resonance (ECR) plasma processing apparatus, or other types of processing systems or combinations of systems. Accordingly, those skilled in the art will understand that the technology described herein may be utilized with any of a wide variety of plasma processing systems.

[0043] Plasma processing system 400 may be used for a wide variety of operations, including, but not limited to, etching, deposition, cleaning, plasma polymerization, plasma-enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), atomic layer etching (ALE), etc. The construction of plasma processing system 400 is well known, and the particular construction described herein is for illustrative purposes only. It will be understood that different and / or additional plasma processing systems may be implemented while still utilizing the techniques described herein.

[0044] Looking more specifically at FIG. 4 , the plasma processing system 400 may include a process chamber 405. The process chamber 405 may be a pressure-controlled chamber, as is known in the art. A substrate 410 (in one example, a semiconductor wafer) may be held on a stage or chuck 415. As shown, an upper electrode 420 and a lower electrode 425 may be provided. The upper electrode 420 may be electrically coupled to a first radio frequency (RF) power source 430 through a first matching network 455. The first RF power source 430 may generate an upper frequency (f U ) may be supplied to the lower electrode 425. The lower electrode 425 may be electrically coupled to a second RF power source 440 through a second matching network 457. The second RF power source 440 may be connected to a lower frequency (f L ) may provide a bias voltage 445. Although not shown, it is well known to those skilled in the art that a voltage may also be applied to the chuck 415.

[0045] The components of plasma processing system 400 may be connected to and controlled by control unit 470. Control unit 470 may, in turn, be connected to corresponding memory storage units and user interfaces (all not shown). Various plasma processing operations may be performed via the user interface, and various plasma processing recipes and operations may be stored in the storage unit. Thus, a given substrate may be processed using various micromachining techniques in the plasma processing chamber. It will be understood that control unit 470 may be coupled to various components of plasma processing system 400 to receive inputs from the components and provide outputs to the components.

[0046] The control unit 470 can be implemented in a wide variety of ways. For example, the control unit 470 can be a computer. In another example, the control unit can include one or more programmable integrated circuits programmed to provide the functionality described herein. For example, one or more processors (e.g., microprocessors, microcontrollers, central processing units, etc.), programmable logic devices (e.g., complex programmable logic devices (CPLDs), field programmable gate arrays (FPGAs), etc.), and / or other programmable integrated circuits can be programmed with software or other programming instructions to implement the functionality of a proscribed plasma process recipe. It is further noted that the software or other programming instructions can be stored on one or more non-transitory computer-readable media (e.g., memory storage devices, FLASH memory, dynamic random access (DRAM) memory, reprogrammable storage devices, hard drives, floppy disks, DVDs, CD-ROMs, etc.), and that the software or other programming instructions, when executed by the programmable integrated circuit, cause the programmable integrated circuit to perform the processes, functions, and / or capabilities described herein. Other variations can also be implemented.

[0047] In operation, the plasma processing system 400 uses upper and lower electrodes to generate a plasma 460 within the process chamber 405 when power is applied to the system from a first RF power source 430 and a second RF power source 440. Upon application of power, a radio frequency electric field is generated between the upper electrode 420 and the lower electrode 425. Process gases delivered to the process chamber 405 may then be dissociated and converted into the plasma 460. The generated plasma 460 may be used to process a target substrate (e.g., a substrate 410 or any material to be processed) in various types of processes, such as, but not limited to, plasma deposition, etching, and / or ion bombardment / sputtering.

[0048] In some embodiments, the selective deposition and etching steps disclosed herein may be performed simultaneously using the same plasma 460. For example, a hydrocarbon (e.g., CH4) based plasma 460 may be utilized to selectively deposit a protective layer on the unexposed portions 116 and selectively etch the exposed portions 114 of the patterned layer 108. In other embodiments, the selective deposition and etching steps disclosed herein may use different plasmas 460 that are separated within the process chamber 405, for example, by one or more purge steps.

[0049] 4, the exemplary plasma processing system 400 described herein utilizes two RF power sources. In the exemplary embodiment, a first RF power source 430 provides source power at a relatively high frequency to convert the process gas delivered to the process chamber 405 into a plasma and control the plasma density, while a second RF power source 440 provides bias power at a lower frequency to control the ion bombardment energy.

[0050] In one exemplary plasma processing system, a first RF power source 430 may supply source power of approximately 0-1400 W to the upper electrode 420 in a high frequency (HF) range of approximately 3 MHz to 150 MHz (or greater), and a second RF power source 440 may supply bias power of approximately 0-1400 W to the lower electrode 425 in a low frequency (LF) range of approximately 0.2 MHz to 60 MHz. Different operating ranges may be used depending on the type of plasma processing system and the type of process being performed (e.g., etching, deposition, sputtering, etc.).

[0051] 1D may be performed under the following process conditions: source power between 50 W and 1000 W, bias power between 0 W and 200 W, pressure between 10 mT and 200 mT, electrostatic chuck temperature between 0° C. and 150° C., and CH gas flow of 50 standard cubic centimeters (SCCM). Other gases, such as CHF, CHF, etc., may also be used in the gas flow.

[0052] In one exemplary embodiment, the second plasma 122 used in the etching step shown in FIG. 1E may be performed under process conditions of a source power of 50 W to 1000 W, a bias power of 0 W to 200 W, a pressure of 10 mT to 200 mT, an electrostatic chuck temperature of 10° C. to 150° C., and a CH gas flow of 20 to 100 standard cubic centimeters (SCCM). Other gases, such as Cl, BCl, or inert gases, may also be used in the gas flow. In some embodiments, the bias power may be adjusted or controlled to control the ion bombardment energy during the etching step. In some embodiments, a separate surface activation / ion bombardment step may be performed under process conditions of a source power of 100 W to 500 W, a bias power of 0 W to 200 W, a pressure of 10 mT to 200 mT, an electrostatic chuck temperature of 10° C. to 200° C., and an Ar gas flow of 800 standard cubic centimeters (SCCM). Other gases, such as He, Ne, or Kr, may also be used in the gas flow.

[0053] It should be noted that the techniques described herein may be utilized in a wide variety of plasma processing systems. While a particular plasma processing system 400 is illustrated in FIG. 4 , it will be understood that the techniques described herein may be utilized in other plasma processing systems. In one exemplary system, the RF power sources illustrated in FIG. 4 may be interchanged (e.g., a higher frequency may be supplied to the lower electrode 425 and a lower frequency may be supplied to the upper electrode 420). Furthermore, in FIG. 4 , a dual power supply system is illustrated merely as an exemplary system. It will be understood that the techniques described herein may be utilized with other plasma processing systems in which modulated RF power is supplied to one or more electrodes, a direct current (DC) bias power supply is utilized, or other system components are utilized.

[0054] It should be noted that a variety of deposition processes can be used to form one or more of the material layers described herein. For example, chemical vapor deposition (CVD), plasma-enhanced CVD (PECVD), physical vapor deposition (PVD), atomic layer deposition (ALD), and / or other deposition processes can be used to achieve deposition of one or more layers. Exemplary plasma deposition processes can use precursor gas mixtures including, but not limited to, hydrocarbons and fluorocarbons, optionally in combination with one or more diluent gases (e.g., argon, nitrogen, etc.), under various pressure, power, flow, and temperature conditions.

[0055] It is further noted that various etching processes can be used to etch one or more of the material layers shown and described herein. For example, one or more etching processes can be achieved using a plasma etching process, a discharge etching process, and / or other desired etching processes. The plasma etching processes described herein can be achieved using plasmas containing hydrogen, halocarbons and other halogen-containing chemicals, argon, and / or other gases. As mentioned above, one or more operating parameters (e.g., bias power) of the plasma etching processes described herein can be adjusted to control ion bombardment energy during the etching process.

[0056] Other operating variables for the process steps can also be adjusted to control the various deposition and / or etching processes described herein. The operating variables can include, for example, chamber temperature, chamber pressure, gas flow rate, gas type, and / or other operating variables for the processing steps. Variations can also be implemented while still utilizing the techniques described herein.

[0057] It should be noted that throughout this specification, references to "one embodiment" or "an embodiment" mean that a particular feature, structure, material, or characteristic described in connection with that embodiment is included in at least one embodiment of the invention, but do not indicate that it is present in all embodiments. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification do not necessarily refer to the same embodiment of the invention. Furthermore, particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments. In alternative embodiments, various additional layers and / or structures may be included and / or described features may be omitted.

[0058] As used herein, the term "substrate" refers to and includes a base material or structure upon which a material is formed. It will be understood that a substrate can include a single material, multiple layers of different materials, one or more layers having regions of different materials or structures, etc. These materials can include semiconductors, insulators, conductors, or combinations thereof. For example, the substrate can be a semiconductor substrate, a base semiconductor layer on a supporting structure, a metal electrode, or a semiconductor substrate having one or more layers, structures, or regions formed thereon. The substrate can be a conventional silicon substrate or other bulk substrate including a layer of semiconducting material. As used herein, the term "bulk substrate" refers to and includes not only silicon wafers, but also silicon-on-insulator ("SOI") substrates such as silicon-on-sapphire ("SOS") substrates and silicon-on-glass ("SOG") substrates, epitaxial layers of silicon on a base semiconductor substrate, and other semiconductor or optoelectronic materials, such as silicon germanium, germanium, gallium arsenide, gallium nitride, and indium phosphide. The substrate may be doped or undoped.

[0059] Systems and methods for processing a substrate are described in various embodiments. The substrate may include any material portion or structure of a device, particularly a semiconductor or other electronic device, and may be, for example, a base substrate structure such as a semiconductor substrate, or a layer, e.g., a thin film, on or overlying the base substrate structure. Thus, substrate is not intended to be limited to any particular base structure, underlying layer, or overlying layer, patterned or unpatterned, but rather is intended to include any such layer or base structure, and any combination of layers and / or base structures.

[0060] As will be understood by those skilled in the art, various embodiments may be practiced without one or more of the specific details, or with other alternative and / or additional methods, materials, or components. In other instances, well-known structures, materials, or operations have not been shown or described in detail to avoid obscuring aspects of the various embodiments of the invention. Similarly, for purposes of explanation, specific numbers, materials, and configurations are set forth to provide a thorough understanding of the invention. Nevertheless, the invention may be practiced without the specific details. Furthermore, it should be understood that the various embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale.

[0061] Further modifications and alternative embodiments of the described systems and methods will be apparent to those skilled in the art in light of this specification. Accordingly, it will be understood that the described systems and methods are not limited by these exemplary configurations. It should be understood that the forms of the systems and methods shown and described herein are to be construed as exemplary embodiments. Various changes in implementation are possible. Thus, while the present invention is described herein with reference to specific embodiments, various modifications and changes can be made without departing from the spirit of the invention. Accordingly, the specification and drawings should be regarded in an illustrative rather than a restrictive sense, and such modifications are intended to be included within the scope of the present invention. Furthermore, any benefits, advantages, or solutions to problems described herein with respect to particular embodiments are not intended to be construed as any or all critical, necessary, or essential features or elements of the claims.

Claims

1. 1. A method for patterning a substrate, the method comprising: forming a patterning layer and one or more underlayers on the substrate, the patterning layer comprising a metal oxide photoresist; performing an extreme ultraviolet (EUV) or shorter wavelength lithography process, wherein portions of the patterning layer not covered by an overlying mask are exposed to EUV or shorter wavelength light; performing an iterative dry process to remove the portions of the patterning layer exposed to the EUV or shorter wavelength light and develop a metal oxide photoresist pattern.

2. The repeated dry process comprises: selectively depositing a protective layer on unexposed portions of the patterned layer by exposing the substrate to a first plasma, the unexposed portions of the patterned layer being covered by the overlying mask and not exposed to the EUV or shorter wavelength light; selectively etching the exposed portions of the patterning layer by exposing the substrate to a second plasma, the exposed portions of the patterning layer not covered by the overlying mask and exposed to the EUV or shorter wavelength light; repeating said selective depositing and said selective etching until said exposed portions of said patterning layer are completely removed.

3. The method of claim 2 , wherein the first plasma comprises a hydrocarbon or fluorocarbon precursor gas.

4. The method of claim 2 , wherein the second plasma comprises a hydrogen or halogen-containing precursor gas and an inert gas.

5. 5. The method of claim 4, wherein each time the selective etching step is performed, the hydrogen or halogen-containing precursor gas converts the surface of the exposed portions of the patterned layer into a volatile material, and ions of the inert gas bombard the surface of the substrate to remove the volatile material from the exposed portions.

6. The method of claim 5 , wherein a new protective layer is deposited on the unexposed portions of the patterned layer each time the selective deposition step is performed.

7. 1. A method for patterning a substrate, the method comprising: forming a patterning layer and one or more underlayers on the substrate, the patterning layer comprising a metal oxide photoresist; exposing portions of the patterning layer not covered by a mask above the patterning layer to extreme ultraviolet (EUV) light or shorter wavelength light; selectively depositing a protective layer on unexposed portions of the patterned layer by exposing the substrate to a first plasma, the unexposed portions of the patterned layer being covered by the mask and not exposed to the EUV or shorter wavelength light; selectively etching the exposed portions of the patterned layer by exposing the substrate to a second plasma; repeating the selective deposition and the selective etching until the exposed portions of the patterned layer are completely removed.

8. 8. The method of claim 7, wherein the patterned layer comprises a metal oxide material including clusters of metal oxide structures with chemically bonded organic ligands, and wherein the portions of the patterned layer not covered by a patterned mask layer are exposed to EUV light or shorter wavelength light to separate the organic ligands from the metal oxide structures while leaving the unexposed portions of the patterned layer unchanged.

9. 9. The method of claim 8, wherein the method further comprises performing a bake process after exposing the portions of the patterning layer not covered by the patterned mask layer to EUV light or shorter wavelength light and before selectively depositing the protective layer on the unexposed portions of the patterning layer to release the organic ligands from the exposed portions of the patterning layer.

10. The method of claim 7 , wherein the first plasma comprises a hydrocarbon or fluorocarbon precursor gas.

11. The first plasma is CH ４ , C ４ F ８ , C ４ F ６ , or CH ３ The method of claim 10, comprising F.

12. The method of claim 7 , wherein the second plasma comprises a hydrogen or halogen-containing precursor gas.

13. The second plasma is CH ４ , C.F. ４ , CHF ３ , or BCl ３ 13. The method of claim 12, comprising:

14. The method of claim 12 , wherein the second plasma further comprises an inert gas.

15. The method of claim 8 , wherein the second plasma further comprises argon (Ar).

16. 13. The method of claim 12, wherein the hydrogen or halogen-containing precursor gas converts the surface of the exposed portions of the patterned layer into a volatile material, and inert gas ions bombard the surface of the exposed portions to remove the volatile material.

17. 8. The method of claim 7, wherein the selective deposition of a protective layer on unexposed portions of the patterned layer and the selective etching of exposed portions of the patterned layer are performed simultaneously in a plasma processing chamber using the same plasma precursor gases that generate the first plasma and the second plasma.

18. 20. The method of claim 17, wherein the first plasma and the second plasma each comprise a hydrocarbon precursor and an inert gas.

19. 8. The method of claim 7, wherein the selective deposition of a protective layer on unexposed portions of the patterned layer and the selective etching of exposed portions of the patterned layer are separated in a plasma processing chamber such that the first plasma and the second plasma are generated using different plasma precursor gases.

20. 20. The method of claim 19, wherein the first plasma comprises a hydrocarbon precursor and the second plasma comprises a halocarbon precursor and an inert gas.

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