Metal oxide resist for EUV patterning and its development method

Abstract

A method for processing a substrate includes forming a metal oxide resist on the substrate, exposing the metal oxide resist to an extreme ultraviolet light pattern, and flowing a selective gas over the metal oxide resist. The selective gas increases the selectivity of the exposed metal oxide resist to a developer gas. The method further includes flowing the developer gas over the metal oxide resist in a processing chamber and etching the substrate using remaining portions of the metal oxide resist as a mask.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Non-Provisional Patent Application No. 17 / 880,479, filed August 3, 2022, which is incorporated herein by reference.

[0002] The present invention relates generally to the field of semiconductor manufacturing and semiconductor devices, and in particular, in embodiments, to a method for processing a substrate using extreme ultraviolet (EUV) patterning. [Background technology]

[0003] Photolithography is commonly used to pattern thin films during semiconductor processing, where a light source emits photons onto a light-sensitive photoresist to initiate a chemical reaction in the photoresist, which is then developed to remove exposed or unexposed portions of the photoresist to form a pattern or mask.

[0004] The scaling of semiconductor devices has enabled significant technological advances, including advanced lithography techniques such as immersion lithography. Extreme ultraviolet (EUV) radiation can be used to provide improved pattern resolution in advanced integrated circuits, where reduced feature sizes are required. Typical EUV photoresists are polymer-based chemically amplified resists (CARs) that are deposited onto substrates using liquid-based spin-on techniques that consume large amounts of precursor complexes. Recently, inorganic-based resists have attracted attention because they can be patterned using EUV radiation and can provide the high etch resistance and etch selectivity required for semiconductor manufacturing. However, processing and developing inorganic-based resists present new challenges. Summary of the Invention [Means for solving the problem]

[0005] According to one embodiment, a method for processing a substrate includes receiving a first substrate having exposed metal oxide resist in a processing chamber, the exposed metal oxide resist including exposed and unexposed portions; flowing a selective gas over the exposed metal oxide resist, the selective gas increasing selectivity between the exposed and unexposed portions of the exposed metal oxide resist to a developer gas; and flowing the developer gas over the exposed metal oxide resist in the processing chamber.

[0006] According to another embodiment, a method for processing a substrate includes forming a metal oxide resist on the substrate, exposing the metal oxide resist to an extreme ultraviolet light pattern, flowing a first selective gas over the metal oxide resist in a processing chamber, after flowing the first selective gas, simultaneously flowing a developer gas and a second selective gas over the metal oxide resist in the processing chamber, wherein the developer gas includes an element that is not part of the first selective gas or the second selective gas, and etching the substrate using remaining portions of the metal oxide resist as a mask.

[0007] According to yet another embodiment, a method for processing a substrate includes forming a metal oxide resist on the substrate, exposing the metal oxide resist to an extreme ultraviolet light pattern, flowing a first developer gas over the metal oxide resist in a processing chamber, purging the first developer gas from the processing chamber with a first selective gas, the first selective gas having a different molecular structure than the first developer gas, flowing a second developer gas over the metal oxide resist in the processing chamber after purging the first developer gas, and etching the substrate using remaining portions of the metal oxide resist as a mask.

[0008] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure, as claimed.

[0009] For a more complete understanding of the present invention and its advantages, reference is now made to the following descriptions taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0010] [Figure 1A] 1A-1C illustrate steps in an exemplary manufacturing process for forming and exposing photoresist, according to various embodiments. [Figure 1B] 1A-1C illustrate steps in an exemplary manufacturing process for forming and exposing photoresist, according to various embodiments. [Figure 1C] 1A-1C illustrate steps in an exemplary manufacturing process for forming and exposing photoresist, according to various embodiments. [Figure 2A] 1A-1C illustrate steps in an exemplary development process for photoresist, according to various embodiments. [Figure 2B] 1A-1C illustrate steps in an exemplary development process for photoresist, according to various embodiments. [Figure 2C] 1A-1C illustrate steps in an exemplary development process for photoresist, according to various embodiments. [Figure 3A] 1A-1C illustrate steps in an exemplary manufacturing process for forming conductive features in and on a substrate, according to various embodiments. [Figure 3B] 1A-1C illustrate steps in an exemplary manufacturing process for forming conductive features in and on a substrate, according to various embodiments. [Figure 3C] 1A-1C illustrate steps in an exemplary manufacturing process for forming conductive features in and on a substrate, according to various embodiments. [Figure 3D] 1A-1C illustrate steps in an exemplary manufacturing process for forming conductive features in and on a substrate, according to various embodiments. [Figure 4] FIG. 1 is a process flow chart diagram of a method for processing a substrate, according to various embodiments. [Figure 5]FIG. 1 is a process flow chart diagram of a method for processing a substrate, according to various embodiments. [Figure 6] FIG. 1 is a process flow chart diagram of a method for processing a substrate, according to various embodiments. [Figure 7] FIG. 1 is a process flow chart diagram of a method for processing a substrate, according to various embodiments. [Figure 8] FIG. 1 is a process flow chart diagram of a method for processing a substrate, according to various embodiments. [Figure 9] FIG. 1 is a process flow chart diagram of a method for processing a substrate, according to various embodiments. [Figure 10] FIG. 1 is a process flow chart diagram of a method for processing a substrate, according to various embodiments. [Figure 11] FIG. 1 is a process flow chart diagram of a method for processing a substrate, according to various embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0011] Corresponding numerals and symbols in different drawings generally refer to corresponding parts unless otherwise indicated. The drawings are drawn to clearly show relevant aspects of the embodiments and are not necessarily drawn to scale. The edges of features drawn in the drawings do not necessarily indicate the ends of the extents of the features.

[0012] Making and using various embodiments is described in detail below. However, it should be understood that the various embodiments described herein can be applied in a variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the various embodiments and should not be construed as limiting in scope.

[0013] According to one or more embodiments of the present disclosure, the present application relates to a method for developing inorganic resists (e.g., metal oxide resists) for EUV patterning that improves the selectivity of the development process. The selectivity of the development process (e.g., dry etching process) to exposed and unexposed regions of a photoresist film can be improved by adding a secondary gas, called a selectivity gas, to the processing chamber along with the development gas. The selectivity gas can be introduced into the processing chamber in a variety of ways, including as a processing step prior to introducing the development gas, simultaneously with the development gas, alternating with the development gas in a cyclical manner, or combining some or all of these approaches. Embodiments can improve the selectivity of the development etch. This can improve the mask budget for pattern transfer by allowing thicker resist to remain after development. This can enable pattern transfer to thicker underlayers. Embodiments can enable reduced development doses and exposure times, thereby improving process throughput. Furthermore, embodiments can enable tuning the selectivity of the development process by selecting an appropriate chemistry for the selectivity gas. For example, the selectivity of the development process can be reversed, e.g., a negative-tone photoresist can become a positive-tone photoresist.

[0014] Embodiments of the present disclosure are described in the context of the accompanying drawings. An exemplary manufacturing process embodiment including the formation and exposure of an EUV-sensitive photoresist film is described using FIGS. 1A-1C. An exemplary development process embodiment including a developer gas and a selective gas is described using FIGS. 2A-2C. An exemplary manufacturing process embodiment for forming conductive features in and on a substrate is described using FIGS. 3A-3D. An exemplary method embodiment for processing a substrate including the flow of a developer gas and a selective gas is described using FIGS. 4, 5, 6, 7, 8, 9, 10, and 11.

[0015] 1A-1C illustrate steps in an exemplary manufacturing process, including the formation and exposure of an EUV-sensitive photoresist film. FIG. 1A illustrates a cross-sectional view of an exemplary substrate 100 to be patterned. For example, substrate 100 may be a silicon wafer having a diameter in the range of 100 mm to 500 mm, such as 150 mm, 200 mm, 300 mm, or 450 mm. In various embodiments, substrate 100 may be part of or include a semiconductor device, e.g., may have undergone multiple processing steps following conventional processing. Thus, substrate 100 may include layers of various semiconductors useful in microelectronics. For example, a semiconductor structure may include substrate 100 upon which various device regions are formed.

[0016] In one or more embodiments, substrate 100 may be a silicon wafer or a silicon-on-insulator (SOI) wafer. In particular embodiments, substrate 100 may include silicon germanium, silicon carbide, gallium arsenide, gallium nitride, or other compound semiconductors. In other embodiments, substrate 100 includes heterogeneous layers, such as silicon germanium-on-silicon, gallium nitride-on-silicon, or silicon carbon-on-silicon, as well as layers of silicon-on-silicon or SOI substrates. In various embodiments, substrate 100 is patterned or embedded with other components of a semiconductor device. In some embodiments, substrate 100 includes conductive features 101 (e.g., metal lines) embedded therein. Conductive features 101 may be electrically coupled to active devices (not shown) further embedded within substrate 100.

[0017] FIG. 1B shows a cross-sectional view of substrate 100 after depositing a photoresist film 102 (e.g., a metal oxide resist) thereon. In various embodiments, although not shown, substrate 100 may further include various layers useful in semiconductor device fabrication, which may be collectively considered part of substrate 100 in this disclosure. For example, in certain embodiments, a dielectric layer may be present on substrate 100, including a silicon-based dielectric material with a low dielectric constant (i.e., low k value), such as organosilicate glass (SiCOH), dense SiCOH, porous SiCOH, and other porous dielectric materials. Additionally, there may be a hard mask layer on substrate 100, which may be patterned in a subsequent etching process after EUV photopatterning. In various embodiments, the hard mask may include titanium nitride, titanium, titanium oxide, tantalum, tungsten carbide, other tungsten-based compounds, ruthenium-based compounds, or aluminum-based compounds. The hard mask may also be a carbon-based or silicon-based mask material.

[0018] In one example shown in FIG. 1B , a photoresist film 102 is formed on the substrate 100. Additionally, the photoresist film 102 may be formed as part of a three-layer stack, commonly used in photolithographic patterning. The three-layer stack may be used to generate and transfer a pattern to a hard mask and then to an underlying layer, such as a dielectric layer of the substrate 100. In various embodiments, the multilayer stack includes an underlayer and the photoresist film 102 as an EUV-sensitive photoresist on the underlayer. In one or more embodiments, the underlayer includes a carbon material (e.g., silicon carbide or silicon oxide) and may be formed by a spin-on process or vapor deposition such as CVD. The multilayer stack may further include a layer of oxide (e.g., silicon oxide) or nitride (e.g., titanium nitride or silicon nitride) on the underlayer and the photoresist film 102. For simplicity of explanation, FIG. 1B shows only a photoresist film 102 deposited directly on the substrate 100, however, as noted above, in various embodiments, any suitable multi-layer structure may be present as part of the substrate 100.

[0019] In various embodiments, the photoresist film 102 includes tin (Sn), antimony (Sb), hafnium (Hf), zirconium (Zr), zinc (Zn), or the like, or a combination thereof. In particular embodiments, the photoresist film 102 includes a metal oxide, metal alkoxide, or methacrylate (MAA) of tin, antimony, hafnium, zirconium, zinc, or the like, such as ZrMAA, SbMAA, SbMAA:F, HfMAA, ZnMAA, and ZnMAA:F. In particular embodiments, the photoresist film 102 can be a metal oxide network including metal alkoxide, metal alkene oxide, metal aryloxide, or metal carboxylate groups. These groups bonded to the metal are generally represented by the formulas -OR, -OR', -OAr, and -OOCR, respectively, where R is an alkyl group, R' is an alkene group, and Ar is an aryl group. In various embodiments, the photoresist film 102 is a polymer film and may not have a highly ordered structure, such as a crystalline structure. The number of functional groups attached to the metal atoms may vary from one to four. Deposition of the photoresist film 102 may be performed by a dry process or a wet process. In various embodiments, the photoresist film 102 may be deposited by vapor deposition, such as chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), or plasma enhanced ALD (PEALD).

[0020] In certain embodiments, a deposition process for the photoresist film 102 may include exposing the substrate 100 to two precursors in a processing chamber: a metal-containing precursor (e.g., a tin-containing precursor) and an oxygen-containing precursor. The exposure to these precursors may be performed stepwise or simultaneously. In various embodiments, the deposition process may be an ALD or pseudo-ALD process and may include two or more exposure steps. For example, the deposition process may be performed by first exposing the substrate 100 to a tin-containing precursor that forms an adsorbed layer on the substrate 100, and then exposing the substrate 100 to an oxygen-containing precursor gas that reacts with the adsorbed tin-containing precursor. The exposure step may be repeated one or more times to increase the thickness of the photoresist film 102 on the substrate 100. In certain embodiments, the exposure steps may be separated in time or space. Temporal separation of the exposure steps may be achieved by varying the gas composition in the processing chamber. Meanwhile, spatial separation of the exposure steps may be enabled by utilizing multiple spatially separated zones in the processing chamber and transporting the substrate from one zone to another. To further separate the exposure steps in time, the deposition may further include evacuation, purging, or both evacuation and purging between the exposure steps. These additional steps may be beneficial in ensuring that reactions occur only on the surface and not in the gas phase. The ALD or pseudo-ALD method according to the present embodiment may be particularly advantageous in enabling layer-by-layer growth of the photoresist film 102 with high uniformity.

[0021] In another embodiment, rather than an ALD-type process, the precursors may be supplied simultaneously to the processing chamber to grow the photoresist film 102. Such an embodiment may be advantageous by allowing for sequential growth of the photoresist film 102 in a single step. In this embodiment, the reaction between the precursors may or may not occur in the gas phase as well as on the surface.

[0022] In other embodiments, the photoresist film 102 can be deposited by liquid deposition using alternating exposures of tin-containing precursor liquids and oxygen-containing precursor liquids. Liquid deposition can further include rinsing the substrate with a rinse solution between exposure steps to remove excess and / or unreacted precursors. The rinse solution can include common organic solvents such as deionized water, acetone, propylene glycol monomethyl ether acetate, 1-methoxy-2-propanol, methyl isobutyl carbinol, hexane, tert-butanol, and isopropanol, or mixtures thereof. In another embodiment, the liquid precursors can be mixed first, and the mixed solution can be applied to the substrate to grow the photoresist film 102. In one or more embodiments, one of the precursors can be gaseous and the other can be liquid, and accordingly, two different modes of delivery (vapor and liquid) can be utilized to carry out the deposition process.

[0023] In various embodiments, after the photoresist film 102 is formed on the substrate 100, an optional post-apply bake may be performed to remove any excess solvent from the wet process, residual volatile by-products from the dry process, or both.

[0024] FIG. 1C shows a cross-sectional view of the substrate 100 after exposure to a light pattern, such as EUV exposure. The method further includes exposing the substrate 100 to an EUV light pattern 104, as shown schematically in FIG. 1C. A photomask can be used to create the EUV light pattern 104 by placing the photomask between the substrate 100 and an EUV light source (not shown). In response to exposure to the EUV light pattern 104, a photochemical reaction can occur in the exposed regions 105 of the photoresist film 102, while the unexposed regions 107 remain unchanged. As a result of the photochemical reaction, the exposed regions 105 may comprise a crosslinked photoresist film, which can have material properties that are substantially different from those of the unreacted portions of the photoresist film 102 (i.e., the unexposed regions 107). Such differences in material properties include, among other things, volatility, reactivity, and / or solubility, which result from the tonality of the photoresist.

[0025] In various embodiments, after EUV exposure (see FIG. 1C, above) and before the development step (see FIG. 2A, above), an optional post-exposure bake (PEB) may be performed to further differentiate material properties between exposed and unexposed regions 105 and 107. In certain embodiments, the PEB may be performed by heating substrate 100 in a processing chamber under vacuum or gas flow at a temperature between 70° C. and 250° C., for example, in one embodiment, between 180° C. and 225° C.

[0026] 2A-2C illustrate steps in a development process of a photoresist film 102, according to some embodiments, including a selective gas 112 and a developer gas 122. The use of the selective gas 112 in addition to the developer gas 122 improves the selectivity of the development process (e.g., a dry etching process) to exposed and unexposed areas of the photoresist film.

[0027] 2A, continuing from FIG. 1C, illustrates a cross-sectional view of substrate 100 during the introduction of selective gas 112, according to some embodiments. Substrate 100 is placed in a suitable processing chamber, and selective gas 112 is flowed into the processing chamber. For a negative tune development process (i.e., removal of unexposed regions 107 of photoresist film 102), selective gas 112 may react with exposed regions 107 of photoresist film 102 to improve selectivity with development gas 122. In various embodiments, selective gas 112 is water vapor (HO), chlorine (Cl), bromine (Br), methanol, ethanol, isopropyl alcohol, acetylacetone, acetic acid, a Lewis acid (e.g., boron trichloride (BCl), boron tribromide (BBr), boron trifluoride (BF), borane (BH)), or the like, or a combination thereof. In some embodiments, where R represents hydrogen or an organic moiety having 0-10 carbon atoms, the selective gas 112 is a gas of the general formula ROH, an organic carboxylic acid of the formula RCOOH, a gas having an amine group of the formula R-NH, or the like, or a combination thereof. The selectivity of the development process can be adjusted by selecting an appropriate chemical for the selective gas 112 (e.g., boron trichloride (BCl) or water vapor (HO)). In some embodiments, the photoresist film 102 is saturated with the selective gas 112 in a first processing chamber prior to a development process performed in a second processing chamber using a developer gas 122 (see FIG. 2B, below). The photoresist film 102 can be further exposed to the selective gas 112 in the second processing chamber before, after, during, or a combination thereof, the introduction of the developer gas 122.

[0028] In various embodiments, the selective gas 112 is introduced into the processing chamber at a flow rate ranging from 1 sccm to 1000 sccm. In some embodiments in which the selective gas 112 is introduced into the processing chamber with another gas (e.g., a developer gas, see below, FIG. 2B), the volume percent flow rate of the selective gas 112 is in the range of 0% to 80%. The selective gas 112 may be introduced into the processing chamber when the temperature within the processing chamber is in the range of −30° C. to 200° C. The selective gas 112 may be flowed into the processing chamber under a pressure ranging from 5 mTorr to 100 Torr.

[0029] In FIG. 2B, developer gas 122 is flowed into the processing chamber. Developer gas 122 is a different gas than selective gas 112. In various embodiments, developer gas 122 includes elements that are not part of selective gas 112, or developer gas 122 has a different molecular structure than selective gas 112. Developer gas 122 reacts with unexposed regions 107 of photoresist film 102 to produce volatile by-products, which then evaporate from the surface of substrate 100. This causes unexposed regions 107 to become recessed relative to exposed regions 105, forming openings 108 in photoresist film 102. In some embodiments, developer gas 122 is an inorganic acid (e.g., hydrogen bromide (HBr), hydrogen chloride (HCl), etc.), an organic acid (e.g., acetic acid, trifluoroacetic acid, hexafluoroacetylacetone, acetylacetone, etc.), a Lewis acid (e.g., boron trichloride (BCl), boron tribromide (BBr), etc.), or a combination thereof. In some embodiments, different developing steps are performed using different developing gases 110. For example, a first developing step can be performed using hydrogen bromide and a second developing step can be performed using boron trichloride.

[0030] The development step may be performed using a flow rate of the developer gas 122 ranging from 10 sccm to 2000 sccm. The development step may be performed when the temperature in the processing chamber is in the range of −30° C. to 200° C. The development step may be performed for a duration of a few seconds to 200 seconds.

[0031] 2A-2B illustrate the introduction of selective gas 112 as a processing step in FIG. 2A before the introduction of developer gas 122 in FIG. 2B. However, any suitable order for the introduction of selective gas 112 and developer gas 122 may be used. For example, selective gas 112 may be introduced into the processing chamber simultaneously with developer gas 122, alternately with developer gas 122 in a cyclical manner, or a combination of some or all of these approaches. In some embodiments, different selective gases 112 are used in different steps of the development process. For example, a first selective gas may be used in a processing step before introducing developer gas 122, a second selective gas may be introduced simultaneously with developer gas 122, and / or a third selective gas may be used in a purging step after introducing developer gas 122. In some embodiments, a non-reactive gas (e.g., argon, nitrogen (N), carbon dioxide (CO), etc., or a combination thereof) may be used along with a third selective gas in a purging step following the introduction of the development gas 122, or the purging step may include a non-reactive gas without a selective gas.

[0032] Embodiments may allow for reduced developer dose and exposure time, thereby improving process throughput. Additionally, embodiments may allow for tuning the selectivity of the development process by selecting an appropriate chemistry for the selectivity gas. As an example, using water vapor as the selectivity gas 112 in a processing step prior to introducing the developer gas 122 may substantially reduce the etch rate and etch volume of the exposed regions 105 while less affecting the etch rate and etch volume of the unexposed regions 107, thereby improving the selectivity of the development process. In embodiments in which the photoresist film comprises tin oxide, treatment with water vapor as the selectivity gas 112 prior to etching with the developer gas 122 (e.g., HBr) may result in approximately twice the number of Sn—OH groups in the exposed regions 105 compared to the number of Sn—OH groups in the unexposed regions 105. This increased hydrogen bonding in the exposed regions 105 may result in a lower etch rate and etch volume of the exposed regions 105 compared to the unexposed regions 107.

[0033] As another example, using boron trichloride (BCl) as the selectivity gas 112 in one or more purging steps following each development step using HBr as the development gas 122 can lead to improved selectivity of the development etch by reducing etching of the exposed regions 105 by about 75%. This can be because boron trichloride can bind to active sites in the exposed regions 105 during the purge cycle, which can protect the exposed regions 105 from etching by HBr.

[0034] FIG. 2C illustrates a cross-sectional view of substrate 100 after one or more development steps and one or more purge steps of a cyclical development process, according to some embodiments. After the cyclical development process, exposed regions 105 (see FIGS. 1C-2B, above) have been removed. Openings 108 extend through the remaining unexposed regions 107 of photoresist film 102. A portion of the top surface of substrate 100 is exposed through openings 108. Unexposed regions 107 of photoresist film 102 can then be used as a mask to etch substrate 100, for example, to form conductive features in substrate 100 (see FIGS. 3A-3C, below). Improving the selectivity of the development etch by using selectivity gas 112 with development gas 122 can improve the mask budget for pattern transfer by allowing thicker exposed regions 105 to remain after development.

[0035] 1A-2C, the photoresist film 102 is a negative-tone photoresist. In other embodiments, the photoresist film 102 may form a positive-tone photoresist, in which the exposed regions 105 are removed by a development step, leaving the unexposed regions 107. In one embodiment, the positive-tone photoresist can improve the etch resistance of the unexposed regions 107 after EUV exposure by using a large dose of boron trichloride (BCl3) (e.g., a dose ranging from 5 sccm to 500 sccm) at a temperature range of -30°C to 60°C, while the photoreaction in the exposed regions 105 remains unchanged.

[0036] 3A-3D illustrate cross-sectional views of intermediate steps in an exemplary fabrication process for forming conductive features in and on substrate 100. In FIG. 3A, opening 108 is extended into substrate 100 to form opening 118 using a suitable anisotropic etching technique, such as a reactive ion etching (RIE) process using fluorine chemistry or an atomic layer etching (ALE) process. However, any suitable etching process may be used. Exposed region 105 of photoresist film 102 remains on substrate 100 and serves as a mask for the etching process. In some embodiments, opening 118 exposes a top surface of conductive feature 101 (e.g., a metal line) embedded in substrate 100. The exposed regions 105 remaining after development, with increased thickness due to the improved selectivity resulting from using the selectivity gas 112 with the development gas 122, may be formed deeper than 118. This may allow pattern transfer to thicker underlying layers of the substrate 100.

[0037] 3B, exposed regions 105 of photoresist film 102 are removed from over substrate 100, residue from the etching and planarization processes is removed, and conductive material 130 is formed on substrate 100. Exposed regions 105 of photoresist film 102 may be removed using an appropriate process, such as a planarization process (e.g., CMP). In some embodiments, residue from the etching and planarization processes is removed using a suitable cleaning process, such as rinsing with deionized water, hydrogen peroxide, SC-1, or the like, or a combination thereof.

[0038] Still referring to FIG. 3B, a conductive material 130 is formed on the substrate 100 to fill the opening 118 (see FIG. 3A, above). As an example of forming the conductive material 130, a conformal barrier metal (e.g., TiN or TaN) liner is formed on the exposed surface of the substrate 100. The opening 118 is then filled with the conductive material 130, such as a metal. For example, the conductive material 130 may be copper formed using electroplating. However, any suitable conductive material and deposition method may be used. In some embodiments, the conductive material 130 is in electrical and physical contact with the top surface of the conductive feature 101.

[0039] 3C, a planarization process (e.g., CMP) is used to remove excess conductive material from the top surface of substrate 100, thereby forming conductive feature 132 buried in substrate 100. In various embodiments, conductive feature 132 is a high aspect ratio feature. Conductive feature 132 may be a conductive via that physically and electrically couples with conductive feature 101 of substrate 100.

[0040] 3D, an interconnect layer is formed over the substrate 100 and the conductive features 132. The interconnect layer includes an inter-metal dielectric (IMD) 150 having conductive lines 152 formed therein. The IMD 150 includes an insulating material such as SiO2 or a silicon oxide-based low-k dielectric (e.g., porous oxide, fluorosilicate glass (FSG), and orthosilicate glass (OSG)). In some embodiments, the IMD 150 includes a material such as Si3N4, SiO x N y , SiC, or SiCN, or other suitable dielectric layers. The IMD 150 may be formed by a suitable process, such as CVD.

[0041] 3D , the conductive lines 152 may be formed by a conventional damascene process using a conductive material such as copper. As is well known to those skilled in the art, a damascene process includes patterning an opening (e.g., a trench for the conductive line 152) in the IMD 150, depositing a conformal barrier metal (e.g., TiN or TaN) liner, filling the opening with metal (e.g., using Cu electroplating), and removing any excess conductive material from the top surface of the IMD 150 using a planarization process such as chemical mechanical planarization (CMP), thereby forming the conductive lines 152 embedded in the IMD 150. In some embodiments, each conductive line 152 is formed to electrically and physically couple to one or more underlying conductive features 132 (e.g., conductive vias).

[0042] 4 shows a process flow diagram of a method 200 for processing a substrate, according to some embodiments. In step 202, a photoresist film 102 (e.g., a metal oxide resist) is formed on a substrate 100, as described above with respect to FIG. 1B. In step 204, the photoresist film 102 is exposed to a light pattern (e.g., an EUV light pattern 104), thereby forming a pattern of exposed regions 105 and unexposed regions 107 of the photoresist film 102, as described above with respect to FIG. 1C.

[0043] In step 206, a selective gas 112 is flowed over the photoresist film 102, as described above with respect to Figure 2A. In some embodiments, the selective gas 112 is water vapor, and step 206 is a treatment step that improves the selectivity of a subsequent development step 208. In step 208, a development gas 122 is flowed over the photoresist film 102, as described above with respect to Figure 2A.

[0044] In step 210, as described above with respect to Figure 3A, substrate 100 is etched using remaining portions of photoresist film 102 (e.g., exposed regions 105) as a mask to form openings 118. Conductive features may then be formed in openings 118, as described above with respect to Figures 3B-3C.

[0045] 5 is a process flow diagram of a method 300 for processing a substrate, according to some embodiments. In step 302, a photoresist film 102 (e.g., a metal oxide resist) is formed on a substrate 100, as described above with respect to FIG. 1B. In step 304, the photoresist film 102 is exposed to a light pattern (e.g., an EUV light pattern 104), thereby forming a pattern of exposed regions 105 and unexposed regions 107 of the photoresist film 102, as described above with respect to FIG. 1C.

[0046] In step 306, developer gas 122 and selectivity gas 112 are simultaneously flowed over photoresist film 102, as described above with respect to Figures 2A and 2B. In step 308, as described above with respect to Figure 3A, substrate 100 is etched using remaining portions of photoresist film 102 (e.g., exposed regions 105) as a mask to form openings 118. Conductive features may then be formed in openings 118, as described above with respect to Figures 3B-3C.

[0047] 6 is a process flow diagram of a method 400 for processing a substrate, according to some embodiments. In step 402, a photoresist film 102 (e.g., a metal oxide resist) is formed on a substrate 100, as described above with respect to FIG. 1B. In step 404, the photoresist film 102 is exposed to a light pattern (e.g., an EUV light pattern 104), thereby forming a pattern of exposed regions 105 and unexposed regions 107 of the photoresist film 102, as described above with respect to FIG. 1C.

[0048] Steps 406 and 408 are one cycle of a cyclic development process performed in a processing chamber on the photoresist film 102. In step 406, a developer gas 122 is flowed onto the photoresist film 102, as described above with respect to FIG. 2A. In step 408, the developer gas 122 is purged from the processing chamber by flowing a selective gas 112, as described above with respect to FIG. 2A. In various embodiments, steps 404 and 408 are repeated for a suitable number of cycles, such as 1 to 50 cycles. In some embodiments, the developer gas 122 is HBr and the selective gas is BCl. In some embodiments, different developer gases 122 and / or different selective gases 112 are used for different cycles of the cyclic development process.

[0049] In step 410, substrate 100 is etched using remaining portions of photoresist film 102 (e.g., exposed regions 105) as a mask, as described above with respect to Figure 3A, to form openings 118. Conductive features may then be formed in openings 118, as described above with respect to Figures 3B-3C.

[0050] 7 is a process flow diagram of a method 500 for processing a substrate, according to some embodiments. In step 502, a photoresist film 102 (e.g., a metal oxide resist) is formed on a substrate 100, as described above with respect to FIG. 1B. In step 504, the photoresist film 102 is exposed to a light pattern (e.g., an EUV light pattern 104), thereby forming a pattern of exposed regions 105 and unexposed regions 107 of the photoresist film 102, as described above with respect to FIG. 1C.

[0051] In step 506, a first selective gas 112 is flowed over the photoresist film 102, as described above with respect to Figure 2A. In some embodiments, the first selective gas 112 is water vapor, and step 506 is a treatment step that improves the selectivity of a subsequent development step 508.

[0052] 2A and 2B, the developer gas 122 and the second selective gas 112 are simultaneously flowed over the photoresist film 102. In some embodiments, the first selective gas 112 and the second selective gas 112 are the same gas. In other embodiments, the first selective gas 112 and the second selective gas 112 are different gases. For example, the first selective gas 112 can be BCl3 and the second selective gas 112 can be water vapor.

[0053] In step 510, substrate 100 is etched using the remaining portions of photoresist film 102 (e.g., exposed regions 105) as a mask, as described above with respect to Figure 3A, to form openings 118. Conductive features may then be formed in openings 118, as described above with respect to Figures 3B-3C.

[0054] 8 is a process flow diagram of a method 600 for processing a substrate, according to some embodiments. In step 602, a photoresist film 102 (e.g., a metal oxide resist) is formed on a substrate 100, as described above with respect to FIG. 1B. In step 604, the photoresist film 102 is exposed to a light pattern (e.g., an EUV light pattern 104), thereby forming a pattern of exposed regions 105 and unexposed regions 107 of the photoresist film 102, as described above with respect to FIG. 1C.

[0055] In step 506, a first selective gas 112 is flowed over the photoresist film 102, as described above with respect to Figure 2A. In some embodiments, the first selective gas 112 is water vapor, and step 506 is a treatment step that improves the selectivity of a subsequent development step 508.

[0056] Steps 608 and 610 are each one cycle of a cyclic development process performed in a processing chamber on the photoresist film 102, as described above with respect to steps 606 and 608, as shown in FIG. 6 . In step 606, a developer gas 122 is flowed over the photoresist film 102, as described above with respect to FIG. 2A . In step 608, the developer gas 122 is purged from the processing chamber by flowing a second selective gas 112, as described above with respect to FIG. 2A . In various embodiments, steps 606 and 608 are repeated for a suitable number of cycles, such as 1 to 50 cycles. In some embodiments, the first selective gas 112 and the second selective gas 112 are the same gas. In other embodiments, the first selective gas 112 and the second selective gas 112 are different gases.

[0057] In step 612, substrate 100 is etched using the remaining portions of photoresist film 102 (e.g., exposed regions 105) as a mask, as described above with respect to Figure 3A, to form openings 118. Conductive features may then be formed in openings 118, as described above with respect to Figures 3B-3C.

[0058] 9 is a process flow diagram of a method 700 for processing a substrate, according to some embodiments. In step 702, a photoresist film 102 (e.g., a metal oxide resist) is formed on a substrate 100, as described above with respect to FIG. 1B. In step 704, the photoresist film 102 is exposed to a light pattern (e.g., an EUV light pattern 104), thereby forming a pattern of exposed regions 105 and unexposed regions 107 of the photoresist film 102, as described above with respect to FIG. 1C.

[0059] Steps 706 and 708 are one cycle of a cyclic development process performed in the processing chamber on the photoresist film 102. In step 706, the developer gas 122 and the first selective gas 112 are simultaneously flowed over the photoresist film 102, as described above with respect to FIGS. 2A and 2B. In step 708, the developer gas 122 is purged from the processing chamber by flowing the second selective gas 112, as described above with respect to FIG. 2A. In various embodiments, steps 706 and 708 are repeated for a suitable number of cycles, such as 1 to 50 cycles. In some embodiments, the first selective gas 112 and the second selective gas 112 are the same gas. In other embodiments, the first selective gas 112 and the second selective gas 112 are different gases.

[0060] In step 710, substrate 100 is etched using the remaining portions of photoresist film 102 (e.g., exposed regions 105) as a mask, as described above with respect to Figure 3A, to form openings 118. Conductive features may then be formed in openings 118, as described above with respect to Figures 3B-3C.

[0061] 10 is a process flow diagram of a method 800 for processing a substrate, according to some embodiments. In step 802, a photoresist film 102 (e.g., a metal oxide resist) is formed on a substrate 100, as described above with respect to FIG. 1B. In step 804, the photoresist film 102 is exposed to a light pattern (e.g., an EUV light pattern 104), thereby forming a pattern of exposed regions 105 and unexposed regions 107 of the photoresist film 102, as described above with respect to FIG. 1C.

[0062] In step 806, a first selective gas 112 is flowed over the photoresist film 102, as described above with respect to Figure 2A. In some embodiments, the first selective gas 112 is water vapor, and step 806 is a treatment step that improves the selectivity of a subsequent development step 808.

[0063] Steps 808 and 810 are one cycle of a cyclic development process performed in the processing chamber on the photoresist film 102. In step 808, the developer gas 122 and the second selective gas 112 are simultaneously flowed over the photoresist film 102, as described above with respect to FIGS. 2A and 2B. In step 810, the developer gas 122 is purged from the processing chamber by flowing the third selective gas 112, as described above with respect to FIG. 2A. In various embodiments, steps 806 and 810 are repeated for a suitable number of cycles, such as 1 to 50 cycles. In some embodiments, the first selective gas 112, the second selective gas 112, and the third selective gas 112 are the same gas. In other embodiments, one or more of the first selective gas 112, the second selective gas 112, and the third selective gas 112 are different gases.

[0064] In step 812, substrate 100 is etched using the remaining portions of photoresist film 102 (e.g., exposed regions 105) as a mask, as described above with respect to Figure 3A, to form openings 118. Conductive features may then be formed in openings 118, as described above with respect to Figures 3B-3C.

[0065] 11 is a process flow diagram of a method 900 for processing a substrate, according to some embodiments. In step 902, a substrate 100 having exposed metal oxide resist 102 is received in a processing chamber, as described above with respect to FIG. 2A. The exposed metal oxide resist 102 includes exposed portions 105 and unexposed portions 107.

[0066] In step 904, a selectivity gas 112 is flowed over the exposed metal oxide resist 102, as described above with respect to Figure 2A. The selectivity gas 112 improves the selectivity of the developer gas between the exposed portions 105 and the unexposed portions 107 of the exposed metal oxide resist 102. In step 906, a developer gas 122 is flowed over the exposed metal oxide resist 102 in the processing chamber, as described above with respect to Figure 2B.

[0067]

[0023] Illustrative embodiments of the present disclosure are summarized here. Other embodiments may be understood from the entire specification and claims appended hereto.

[0068] Example 1. A method for processing a substrate, the method comprising: receiving a first substrate having exposed metal oxide resist in a processing chamber, the exposed metal oxide resist including exposed and unexposed portions; flowing a selective gas over the exposed metal oxide resist, the selective gas increasing selectivity between the exposed and unexposed portions of the exposed metal oxide resist to a developer gas; and flowing the developer gas over the exposed metal oxide resist in the processing chamber.

[0069] Example 2. The method of example 1, wherein the selective gas comprises a hydroxide group, an amine group, an organic carboxylic acid, or a Lewis acid.

[0070] Example 3. The method of example 1, wherein the selective gas comprises water vapor, boron trichloride, chlorine, methanol, ethanol, isopropyl alcohol, acetylacetone, or acetic acid.

[0071] Example 4. The method of any one of Examples 1-3, wherein the exposed metal oxide resist comprises tin (Sn), antimony (Sb), hafnium (Hf), zirconium (Zr), or zinc (Zn).

[0072] Example 5. The method of any one of Examples 1-3, wherein the exposed metal oxide resist comprises a metal alkoxide or methacrylate (MAA) of Sn, Sb, Hf, Zr, or Zn.

[0073] Example 6. The method of any one of Examples 1-3, wherein the exposed metal oxide resist comprises a polymer film.

[0074] Example 7. The method of any one of Examples 1-3, wherein the exposed metal oxide resist comprises a metal and a group bonded to the metal, the group having a chemical formula selected from the list of -OR, -OR', -OAr, and -OOCR, where R is an alkyl group, R' is an alkene group, and Ar is an aryl group.

[0075] Example 8. The method of any one of Examples 1-7, wherein the developing gas comprises hydrogen bromide (HBr) or hydrogen chloride (HCl).

[0076] Example 9. The method of any one of Examples 1-7, wherein the developing gas comprises acetic acid, trifluoroacetic acid, hexafluoroacetylacetone, acetylacetone, boron trichloride (BCl3), or boron tribromide (BBr3).

[0077] Example 10. A method for processing a substrate, comprising: forming a metal oxide resist on the substrate; exposing the metal oxide resist to an extreme ultraviolet light pattern; flowing a first selective gas over the metal oxide resist in a processing chamber; after flowing the first selective gas, simultaneously flowing a developer gas and a second selective gas over the metal oxide resist in the processing chamber, wherein the developer gas comprises an element that is not part of the first selective gas or the second selective gas; and etching the substrate using remaining portions of the metal oxide resist as a mask.

[0078] Example 11. The method of example 10, wherein the first selective gas and the second selective gas are the same gas.

[0079] Example 12. The method of example 10, wherein the first selective gas and the second selective gas are different gases.

[0080] Example 13. The method of any one of Examples 1-12, wherein the first selective gas comprises boron trichloride.

[0081] Example 14. The method of any one of Examples 1-13, wherein the developing gas comprises hydrogen bromide and the second selective gas comprises water vapor.

[0082] Example 15. A method for processing a substrate, the method comprising: forming a metal oxide resist on the substrate; exposing the metal oxide resist to an extreme ultraviolet light pattern; flowing a first developer gas over the metal oxide resist in a processing chamber; purging the first developer gas from the processing chamber with a first selective gas, the first selective gas having a different molecular structure than the first developer gas; after purging the first developer gas, flowing a second developer gas over the metal oxide resist in the processing chamber; and etching the substrate using the remaining portion of the metal oxide resist as a mask.

[0083] Example 16. The method of example 15, wherein the first developing gas and the second developing gas are the same gas.

[0084] Example 17. The method of example 16, wherein the same gas comprises hydrogen bromide.

[0085] Example 18. The method of any one of Examples 15-17, wherein the first selective gas comprises water vapor.

[0086] Example 19. The method of any one of Examples 15-18, wherein the first selective gas comprises boron trichloride.

[0087] Example 20. The method of any one of Examples 15-19, further comprising flowing a second selective gas over the metal oxide resist in the processing chamber before flowing the first developing gas, wherein the second selective gas enhances a second selectivity of the exposed metal oxide resist to the first developing gas.

[0088] Although described in detail herein, it should be understood that various changes, substitutions, and alterations can be made therein without departing from the spirit and scope of the present disclosure, as defined by the appended claims. In the various figures, like elements are designated with like reference numerals. Moreover, the scope of the present disclosure is not intended to be limited to the particular embodiments described herein; those skilled in the art will readily appreciate from this disclosure that any now-existing or later-developed process, machine, manufacture, composition of matter, means, method, or step can perform substantially the same function or achieve substantially the same results as the corresponding embodiment described herein. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims

1. 1. A method for processing a substrate, the method comprising: receiving a first substrate having exposed metal oxide resist in a processing chamber, the exposed metal oxide resist including exposed and unexposed portions; flowing a selective gas over the exposed metal oxide resist, the selective gas increasing selectivity between the exposed and unexposed portions of the exposed metal oxide resist to a developer gas; flowing the developer gas over the exposed metal oxide resist in the processing chamber; A method comprising:

2. The method of claim 1 , wherein the selective gas comprises a hydroxide group, an amine group, an organic carboxylic acid, or a Lewis acid.

3. 10. The method of claim 1, wherein the selective gas comprises water vapor, boron trichloride, chlorine, methanol, ethanol, isopropyl alcohol, acetylacetone, or acetic acid.

4. 10. The method of claim 1, wherein the exposed metal oxide resist comprises tin (Sn), antimony (Sb), hafnium (Hf), zirconium (Zr), or zinc (Zn).

5. 10. The method of claim 1, wherein the exposed metal oxide resist comprises a metal alkoxide or methacrylate (MAA) of Sn, Sb, Hf, Zr, or Zn.

6. The method of claim 1 , wherein the exposed metal oxide resist comprises a polymer film.

7. the exposed metal oxide resist comprises a metal and a group bonded to the metal; 2. The method of claim 1, wherein the group has a formula selected from the list of -OR, -OR', -OAr, and -OOCR, where R is an alkyl group, R' is an alkene group, and Ar is an aryl group.

8. 10. The method of claim 1, wherein the developing gas comprises hydrogen bromide (HBr) or hydrogen chloride (HCl).

9. The developing gas may be acetic acid, trifluoroacetic acid, hexafluoroacetylacetone, acetylacetone, boron trichloride (BCl ３ ), or boron tribromide (BBr ３ 10. The method of claim 1, comprising:

10. 1. A method for processing a substrate, the method comprising: forming a metal oxide resist on the substrate; exposing the metal oxide resist to a pattern of extreme ultraviolet light; flowing a first selective gas over the metal oxide resist in a processing chamber; after flowing the first selective gas, co-flowing a developer gas and a second selective gas over the metal oxide resist in the processing chamber, the developer gas including elements that are not part of the first selective gas or the second selective gas; Etching the substrate using the remaining portion of the metal oxide resist as a mask; A method comprising:

11. The method of claim 10 , wherein the first selective gas and the second selective gas are the same gas.

12. The method of claim 10 , wherein the first selective gas and the second selective gas are different gases.

13. The method of claim 10 , wherein the first selective gas comprises boron trichloride.

14. 11. The method of claim 10, wherein the developing gas comprises hydrogen bromide and the second selective gas comprises water vapor.

15. 1. A method for processing a substrate, the method comprising: forming a metal oxide resist on the substrate; exposing the metal oxide resist to a pattern of extreme ultraviolet light; flowing a first developer gas over the metal oxide resist in a processing chamber; purging the first developing gas from the processing chamber with a first selective gas, the first selective gas having a different molecular structure than the first developing gas; after purging the first developer gas, flowing a second developer gas over the metal oxide resist in the processing chamber; Etching the substrate using the remaining portion of the metal oxide resist as a mask; A method comprising:

16. 16. The method of claim 15, wherein the first developer gas and the second developer gas are the same gas.

17. 17. The method of claim 16, wherein the same gas comprises hydrogen bromide.

18. The method of claim 15 , wherein the first selective gas comprises water vapor.

19. 16. The method of claim 15, wherein the first selective gas comprises boron trichloride.

20. further comprising flowing a second selective gas over the metal oxide resist in the processing chamber before flowing the first developing gas; 16. The method of claim 15, wherein the second selectivity gas enhances a second selectivity of the exposed metal oxide resist to the first developer gas.

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