Metal oxide resists for EUV patterning and methods for developing the same

Abstract

A method for processing a substrate includes forming a metal oxide photoresist on the substrate, exposing the metal oxide photoresist to an extreme ultraviolet (EUV) pattern, and flowing a selective gas over the metal oxide photoresist. The selective gas increases the selectivity of the exposed metal oxide photoresist to the developing gas. The method further includes flowing the developing gas over the metal oxide photoresist in a processing chamber and using the remaining portion of the metal oxide photoresist as a mask to etch the substrate.

Description

Technical Field

[0001] The present invention generally relates to the fields of semiconductor manufacturing and semiconductor devices, and in particular embodiments, to methods of processing substrates using extreme ultraviolet (EUV) patterning. [Cross-reference to related applications]

[0002] This application claims the benefit of U.S. Non-provisional Application No. 17 / 880,479, filed on August 3, 2022. The above-referenced application is incorporated herein by reference. Prior Art

[0003] Photolithography is commonly used to pattern thin films during semiconductor processing, where photons are emitted from a light source onto a photosensitive resist, initiating a chemical reaction in the resist. The resist is then developed and either the exposed or unexposed portions of the resist are removed to form a pattern or mask.

[0004] Semiconductor device scaling has seen significant technological advancements, 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 feature sizes need to be reduced. Common EUV photoresists are polymer-based chemically amplified resists (CARs), which are deposited on substrates using liquid-based spin-coating techniques that consume large amounts of complex precursors. Recently, inorganic-based photoresists have gained attention because they can be patterned using EUV radiation and offer the high etch resistance and selectivity required for semiconductor manufacturing. However, processing and developing inorganic-based photoresists present new challenges. Summary of the Invention

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

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

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

[0008] It should be understood that the foregoing general description and the following detailed description are only exemplary and illustrative and are not restrictive of the present disclosure. Simple diagram description

[0009] For a more complete understanding of the present invention and its advantages, reference is now made to the following description in conjunction with the accompanying drawings, in which:

[0010] 1A-1C show steps of an exemplary process for forming and exposing a photoresist according to various embodiments;

[0011] 2A-2C show steps of an exemplary development process for a photoresist according to various embodiments;

[0012] 3A-3D illustrate steps of an exemplary process for forming conductive features in and above a substrate, according to various embodiments;

[0013] FIG4 shows a process flow diagram of a method for processing a substrate according to various embodiments;

[0014] FIG5 shows a process flow diagram of a method for processing a substrate according to various embodiments;

[0015] FIG6 shows a process flow diagram of a method for processing a substrate according to various embodiments;

[0016] FIG7 shows a process flow diagram of a method for processing a substrate according to various embodiments;

[0017] FIG8 shows a process flow diagram of a method for processing a substrate according to various embodiments;

[0018] FIG9 shows a process flow diagram of a method for processing a substrate according to various embodiments;

[0019] FIG. 10 shows a process flow diagram of a method for processing a substrate according to various embodiments; and

[0020] FIG. 11 shows a process flow diagram of a method for processing a substrate, according to various embodiments.

[0021] Unless otherwise indicated, corresponding numbers and symbols in the various figures generally indicate corresponding components. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale. The edges of features depicted in the figures do not necessarily indicate the ends of the features. Implementation Method

[0022] The following details the making and using of various embodiments. However, it should be understood that the embodiments described herein are applicable in many specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the embodiments and should not be construed as limiting.

[0023] According to one or more embodiments of the present disclosure, methods for developing inorganic photoresists (e.g., metal oxide photoresists) used in EUV patterning are provided to improve the selectivity of the development process. Adding an auxiliary gas, known as a selective gas, to a processing chamber containing a developer gas can increase the selectivity of the development process (e.g., a dry etch process) with respect to exposed and unexposed areas of the photoresist film. The selective gas can be introduced into the process chamber in various ways: as a process step prior to the introduction of the developer gas, simultaneously with the developer gas, as a step alternating with the developer gas in a cyclical manner, or as a combination of some or all of the above. These embodiments can increase the selectivity of the development and etch process. This can improve the mask budget for pattern transfer by allowing thicker photoresist to remain after development. This can enable pattern transfer of thicker underlying layers. These embodiments can reduce the developer dosage and exposure time, which can increase process throughput. These embodiments can also adjust the selectivity of the development process by selecting appropriate chemistry for the selective gas. For example, the selectivity of the development process can be reversed, such that a negative-tone photoresist can be turned into a positive-tone photoresist.

[0024] Embodiments of the present disclosure are described in the context of the accompanying drawings. An embodiment of an exemplary process including the formation and exposure of an EUV-sensitive photoresist film will be described using Figures 1A-1C. An embodiment of an exemplary development process including development and selective gases will be described using Figures 2A-2C. An embodiment of an exemplary process for forming conductive features in and above a substrate will be described using Figures 3A-3D. An embodiment of a method for processing a substrate including the flow of development and selective gases will be described using Figures 4, 5, 6, 7, 8, 9, 10, and 11.

[0025] Figures 1A-1C illustrate steps of an exemplary process including the formation and exposure of an EUV-sensitive photoresist film. Figure 1A shows a cross-sectional view of an exemplary substrate 100 to be patterned. For example, substrate 100 may be a silicon wafer having a diameter ranging from 100 mm to 500 mm (e.g., a diameter of 150 mm, 200 mm, 300 mm, or 450 mm). In various embodiments, substrate 100 may be part of or include a semiconductor device and may undergo several processing steps, such as those following conventional processes. Thus, substrate 100 may include semiconductor layers that contribute to various microelectronic devices. For example, a semiconductor structure may include substrate 100 in which various device regions are formed.

[0026] In one or more embodiments, substrate 100 may be a silicon wafer or a silicon-on-insulator (SOI) wafer. In some 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, silicon carbide on silicon, or a silicon layer on a silicon or SOI substrate. In many embodiments, substrate 100 may be patterned or embedded within 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.

[0027] FIG1B shows a cross-sectional view of substrate 100 after a photoresist film 102 (e.g., a metal oxide photoresist) has been deposited thereon. In many embodiments, although not shown, substrate 100 may further include various layers that facilitate semiconductor device fabrication and are collectively considered part of substrate 100 in this disclosure. For example, in some embodiments, substrate 100 may include a dielectric layer comprising a silicon-based dielectric material having a low dielectric constant (i.e., low-k value), such as organosilicate glass (SiCOH), dense SiCOH, porous SiCOH, and other porous dielectric materials. Furthermore, substrate 100 may include a hard mask layer that can be patterned in a subsequent etching process after EUV patterning. In many embodiments, the hard mask layer may include titanium nitride, titanium, titanium oxide, tantalum, tungsten carbide, other tungsten-based compounds, ruthenium-based compounds, or aluminum-based compounds. The hard mask can also be a carbon-based or silicon-based mask material.

[0028] In one example shown in FIG1B , a photoresist film 102 is formed over a substrate 100. Alternatively, the photoresist film 102 may be formed as part of a three-layer stack commonly used for photolithographic patterning. For example, the three-layer stack can be used to create a pattern and transfer it to a hard mask, which is then transferred to an underlying layer, such as a dielectric layer, of the substrate 100. In many embodiments, the multilayer stack includes an underlying layer and the photoresist film 102 as an EUV-sensitive photoresist over the underlying layer. In one or more embodiments, the underlying layer comprises a carbon material (e.g., silicon carbide or silicon oxycarbide) and may be formed via a spin-on process or vapor deposition, such as CVD. The multilayer stack may further include an oxide layer (e.g., silicon oxide) or a nitride layer (e.g., titanium nitride or silicon nitride) over the underlying layer and the photoresist film 102. For simplicity of illustration, FIG1B only shows the photoresist film 102 deposited directly on the substrate 100. However, as described above, in many embodiments, any suitable multilayer structure may be present as part of the substrate 100.

[0029] In many embodiments, the photoresist film 102 comprises tin (Sn), antimony (Sb), hafnium (Hf), zirconium (Zr), zinc (Zn), or combinations thereof. In some embodiments, the photoresist film 102 comprises metal oxides, metal alkoxides, or metal methacrylates (MAAs) of Sn, Sb, Hf, Zr, or Zn, such as ZrMAA, SbMAA, SbMAA:F, HfMAA, ZnMAA, and ZnMAA:F. In some embodiments, the photoresist film 102 may comprise a metal oxide network structure comprising metal alkoxides, metal alkene oxides, metal aryl oxides, or metal carboxylic acid groups. These groups bonded to the metal are typically represented by the chemical 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 many embodiments, the photoresist film 102 is a polymer film and may not have a highly ordered structure, such as a crystalline structure. For each metal atom, the number of functional groups bonded to the metal atom may vary, ranging from 1 to 4. The deposition of the photoresist film 102 may be performed by a dry or wet process. In various embodiments, the photoresist film 102 may be deposited by vapor deposition, such as chemical vapor deposition (CVD), plasma-enhanced CVD (PECVD), atomic layer deposition (ALD), or plasma-enhanced ALD (PEALD).

[0030] In some embodiments, the deposition process for the photoresist film 102 may include exposing the substrate 100 to two precursors in a process chamber: a metal-containing precursor (e.g., a tin-containing precursor) and an oxygen-containing precursor. The exposure to these precursors may be performed sequentially or simultaneously. In many 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, which forms an adsorbed layer on the substrate 100; and then exposing the substrate 100 to an oxygen-containing precursor, which reacts with the adsorbed tin-containing precursor. The exposure steps may be repeated one or more times to increase the thickness of the photoresist film 102 on the substrate 100. In some 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 process chamber. Alternatively, spatially separating the exposure steps can be achieved by using multiple spatially separated zones within the process chamber and transferring the substrate from one zone to another. To further separate the exposure steps temporally, vapor deposition may further include evacuating, purging, or both evacuating and purging the process chamber between exposure steps. These additional steps can help ensure that reactions occur only on the surface and not in the vapor phase. The ALD or quasi-ALD method according to this embodiment is particularly advantageous for achieving layer-by-layer growth of a photoresist film 102 with high uniformity.

[0031] In another embodiment, instead of an ALD process, precursors may be supplied simultaneously within the process chamber to grow the photoresist film 102. This embodiment is advantageous by allowing the photoresist film 102 to continue growing in a single step. In this embodiment, the reaction between the precursors may or may not occur in the vapor phase and on the surface.

[0032] In other embodiments, the photoresist film 102 can be deposited by liquid deposition using alternating exposures of a tin-containing precursor liquid and an oxygen-containing precursor liquid. Liquid deposition may further include rinsing the substrate with a rinse solution to remove excess and / or unreacted precursors between exposure steps. The rinse solution may include deionized water, common organic solvents such as acetone, propylene glycol methyl ether acetate, 1-methoxy-2-propanol, methyl isobutyl carbinol, hexane, tertiary butyl alcohol, and isopropyl alcohol, or mixtures thereof. In another embodiment, the liquid precursors may be mixed first, and the mixture solution may be applied to the substrate to grow the photoresist film 102. In one or more embodiments, one of the precursors may be in a vapor phase, and the other may be in a liquid phase, thereby enabling the deposition process to be performed using two different delivery modes (vapor and liquid).

[0033] In many embodiments, after the photoresist film is formed 102 over the substrate 100, an optional post-application bake may be performed to remove any excess solvent from the wet process, residual volatile byproducts from the dry process, or both.

[0034] Figure 1C shows a cross-sectional view of substrate 100 after exposure to a light pattern (e.g., EUV exposure). As schematically shown in Figure 1C, the method further includes exposing substrate 100 to EUV light pattern 104. A photomask can be used to generate EUV light pattern 104 by placing the photomask between substrate 100 and an EUV light source (not shown). In response to exposure to EUV light pattern 104, a photoreaction can occur in exposed regions 105 of photoresist film 102, while unexposed regions 107 remain unchanged. As a result of the photoreaction, exposed regions 105 can comprise a cross-linked photoresist film having material properties that are substantially different from those of the unreacted portions of photoresist film 102 (i.e., unexposed regions 107). Such differences in material properties, including volatility, reactivity, and / or solubility, can contribute to the photoresist's tunability.

[0035] In many embodiments, after EUV exposure (see FIG. 1C above) and before the development step (see FIG. 2A below), an optional post-exposure bake (PEB) may be performed to further differentiate the material properties between the exposed regions 105 and the unexposed regions 107. In some embodiments, PEB may be performed by heating the substrate 100 in a process chamber in a vacuum or under gas flow at a temperature between 70° C. and 250° C. (e.g., in one embodiment, between 180° C. and 225° C.).

[0036] 2A-2C illustrate steps of a development process for the photoresist film 102 including a selective gas 112 and a developing gas 122, according to some embodiments. The use of the selective gas 112 and the developing gas 122 increases the selectivity of the development process (e.g., a dry etching process) with respect to exposed and unexposed regions of the photoresist film.

[0037] According to some embodiments, FIG2A follows FIG1C and illustrates a cross-sectional view of the substrate 100 during the introduction of the selective gas 112. The substrate 100 is placed in a suitable processing chamber, and the selective gas 112 is flowed into the processing chamber. For a negative-tone development process (i.e., removing the unexposed regions 107 of the photoresist film 102), the selective gas 112 can react with the exposed regions 105 of the photoresist film 102 to increase selectivity with the developing gas 122. In many embodiments, the selective gas 112 is water vapor (H2O), chlorine (Cl2), bromine (Br2), methanol, ethanol, isopropyl alcohol, acetylacetone, acetic acid, a Lewis acid (e.g., boron trichloride (BCl3), boron tribromide (BBr3), boron trifluoride (BF3), borane (BH3)), or a combination thereof. In some embodiments where R represents hydrogen or an organic moiety having 0 to 10 carbon atoms, the selective gas 112 is a gas having the general formula of ROH, an organic carboxylic acid having the chemical formula of RCOOH, a gas having an amine group having the chemical formula of R-NH, or a combination thereof. The selectivity of the development process can be adjusted by selecting an appropriate chemical for the selective gas 112, such as boron trichloride (BCl₃) or water vapor (H₂O). In some embodiments, the photoresist film 102 is saturated with the selective gas 112 in the first process chamber prior to a development process using the developing gas 122 in the second process chamber (see below, FIG. 2B ). The photoresist film 102 may be further exposed to the selective gas 112 in the second process chamber before, after, or during the introduction of the developing gas 122, or a combination thereof.

[0038] In many embodiments, the selective gas 112 is introduced into the process chamber at a flow rate ranging from 1 sccm to 1000 sccm. In some embodiments where the selective gas 112 is introduced into the process chamber along 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 can be introduced into the process chamber at a process chamber temperature ranging from -30°C to 200°C. The selective gas 112 can flow into the process chamber at a pressure ranging from 5 mTorr to 100 Torr.

[0039] In FIG2B , a developing gas 122 flows into the process chamber. The developing gas 122 is a different gas from the selective gas 112. In many embodiments, the developing gas 122 includes an element that is not part of the selective gas 112, or the developing gas 122 has a different molecular structure than the selective gas 112. The developing gas 122 reacts with the unexposed regions 107 of the photoresist film 102 to produce volatile byproducts, which then evaporate from the surface of the substrate 100. This causes the unexposed regions 107 to be recessed relative to the exposed regions 105, forming openings 108 in the photoresist film 102. In some embodiments, the developing gas 122 is an acid (reactive gas) such as 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 (BCl₃), boron tribromide (BBr₃), etc.), or a combination thereof. In some embodiments, different developing steps are performed using different developing gases 122. For example, the first developing step may be performed using hydrogen bromide, and the second developing step may be performed using boron trichloride.

[0040] The development step may be performed using a flow rate of the developing gas 122 in a range of 10 sccm to 2000 sccm. The development step may be performed at a temperature in the process chamber in a range of -30°C to 200°C. The development step may be performed for a duration of a few seconds to 200 seconds.

[0041] Figures 2A-2B show that the selective gas 112 is introduced as a process step in Figure 2A , prior to the introduction of the developer gas 122 in Figure 2B . However, any suitable order of introducing the selective gas 112 and the developer gas 122 may be used. For example, the selective gas 112 may be introduced into the process chamber simultaneously with the developer gas 122, as a step alternating with the developer gas 122 in a cyclical manner, or as a combination of some or all of the above. 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 process step prior to the introduction of the developer gas 122; a second selective gas may be introduced simultaneously with the developer gas 122; and / or a third selective gas may be used in a purge step after the introduction of the developer gas 122. In some embodiments, a non-reactive gas (e.g., argon, nitrogen (N 2 ), carbon dioxide (CO 2 ), or a combination thereof) may be used in the purge step after the introduction of the developer gas 122, along with the third selective gas, or the purge step may include a non-reactive gas without the selective gas.

[0042] Embodiments herein can allow for a reduction in developer dosage and exposure time, which can increase process throughput. Embodiments herein can also allow for tuning the selectivity of the development process by selecting appropriate chemistry for the selective gas. As an example, using water vapor as the selective gas 112 in a treatment step prior to introducing the developer gas 122 can significantly reduce the etch rate and etch amount of the exposed regions 105, while having a smaller impact on the etch rate and etch amount of the unexposed regions 107, thereby increasing the selectivity of the development process. In embodiments where the photoresist film comprises tin oxide, using water vapor as the selective gas 112 prior to etching with the developer gas 122 (e.g., HBr) can result in approximately twice the number of Sn-OH groups in the exposed regions 105 compared to the unexposed regions 107. This increased hydrogen bonding in the exposed regions 105 can result in a lower etch rate and etch amount in the exposed regions 105 compared to the unexposed regions 107.

[0043] As another example, using boron trichloride (BCl3) as the selective gas 112 in one or more purge steps after a corresponding development step using HBr as the development gas 122 can result in improved selectivity in the development etch by reducing the etching of the exposed areas 105 by approximately 75%. This can be due to the boron trichloride bonding to active sites of the exposed areas 105 during the purge cycle, which can protect the exposed areas 105 from being etched by the HBr.

[0044] According to some embodiments, FIG. 2C shows a cross-sectional view of substrate 100 after one or more development steps and one or more purge steps of a cyclic development process. After the cyclic development process is complete, unexposed regions 107 (see above, FIG. 1C-2B ) have been removed. Openings 108 extend through the remaining exposed regions 105 of photoresist film 102. Portions of the top surface of substrate 100 are exposed through openings 108. The exposed regions 105 of photoresist film 102 can subsequently be used as a mask to etch substrate 100, for example, for the formation of conductive features in substrate 100 (see below, FIG. 3A-3C ). The increased development etch selectivity resulting from the use of selective gas 112 and developing gas 122 can improve the mask budget for pattern transfer by allowing thicker exposed regions 105 to remain after development.

[0045] In the embodiments described above with reference to Figures 1A-2C, the photoresist film 102 is a negative-tone photoresist. In other embodiments, the photoresist film 102 can form a positive-tone photoresist, wherein the exposed regions 105 can be removed by a development step, leaving unexposed regions 107. In one embodiment, a positive-tone photoresist can be achieved by using a high dose of boron trichloride (BCl3) (e.g., a dose in the range of 5 sccm to 500 sccm) at a temperature range of -30°C to 60°C to increase the etch resistance of the unexposed regions 107 after EUV exposure, while maintaining the photoreaction in the exposed regions 105 unchanged.

[0046] Figures 3A-3D illustrate cross-sectional views of intermediate steps in an exemplary process for forming conductive features in and above substrate 100. In Figure 3A, opening 108 extends into substrate 100 to form opening 118 using a suitable anisotropic etching technique, such as a reactive ion etch (RIE) process or an atomic layer etch (ALE) process using fluorine chemistry. However, any suitable etching process may be used. Exposed regions 105 of photoresist film 102 remain above substrate 100 and serve as a mask for the etching process. In some embodiments, opening 118 exposes the top surface of conductive features 101 (e.g., metal lines) embedded in substrate 100. The exposed regions 105 that remain after development, having increased thickness due to improved selectivity using selective gas 112 and developing gas 122, allow for the formation of deeper openings 118. This enables pattern transfer to thicker underlying layers of substrate 100.

[0047] In FIG3B , the exposed regions 105 of the photoresist film 102 are removed from the substrate 100, residues from the etching and planarization processes are removed, and a conductive material 130 is formed over the substrate 100. The exposed regions 105 of the photoresist film 102 can be removed using a suitable process, such as a planarization process (e.g., CMP). In some embodiments, residues from the etching and planarization processes are removed using a suitable cleaning process, such as rinsing with deionized water, hydrogen peroxide, SC-1, or a combination thereof.

[0048] Still referring to FIG3B , a conductive material 130 is formed over substrate 100 to fill opening 118 (see FIG3A above). As one example of forming conductive material 130, a conformal barrier metal liner (e.g., TiN or TaN) is formed over the exposed surface of substrate 100. Opening 118 is then filled with conductive material 130, such as a metal. For example, conductive material 130 may be copper formed using electroplating. However, any suitable conductive material and deposition method may be used. In some embodiments, conductive material 130 makes electrical and physical contact with the top surface of conductive feature 101.

[0049] Next, in FIG3C , a planarization process (e.g., CMP) is used to remove excess conductive material from the top surface of substrate 100, thereby forming conductive features 132 embedded in substrate 100. In many embodiments, conductive features 132 are high aspect ratio features. Conductive features 132 can be conductive vias that are physically and electrically coupled to conductive features 101 of substrate 100.

[0050] In FIG3D , an interconnect layer is formed over substrate 100 and conductive features 132. The interconnect layer includes an intermetallic dielectric (IMD) 150 and conductive lines 152 formed therein. IMD 150 comprises an insulating material such as SiO 2 or a silicon oxide-based low-k dielectric, such as porous oxide, fluorosilicate glass (FSG), and orthosilicate glass (OSG). In some embodiments, IMD 150 includes an underlying layer (not shown) comprising an etch stop layer (ESL) of a dielectric such as Si 3 N 4 , SiO x N y , SiC, or SiCN. IMD 150 can be formed using a suitable process such as CVD.

[0051] Still referring to FIG. 3D , for example, conductive lines 152 can be formed using a conventional damascene process using a conductive material such as copper. As known to those skilled in the art, the damascene process includes patterning openings (e.g., trenches for conductive lines 152) in IMD 150; depositing a conformal barrier metal liner (e.g., TiN or TaN); filling the openings with metal (e.g., using Cu electroplating); and removing any excess conductive material from the top surface of IMD 150 using a planarization process such as chemical mechanical planarization (CMP), thereby forming conductive lines 152 embedded in IMD 150. In some embodiments, each conductive line 152 is formed to be electrically and physically coupled to one or more underlying conductive features 132 (e.g., conductive vias).

[0052] FIG4 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 photoresist) is formed over the substrate 100, as described above with respect to FIG1B . In step 204, the photoresist film 102 is exposed to a light pattern (e.g., an EUV light pattern 104), which forms a pattern of exposed regions 105 and unexposed regions 107 of the photoresist film 102, as described above with respect to FIG1C .

[0053] In step 206, the selective gas 112 is flowed over the photoresist film 102, as described above with respect to FIG. 2A . In some embodiments, the selective gas 112 is water vapor, and step 206 is a processing step that increases the selectivity of the subsequent development step 208. In step 208, the developing gas 122 is flowed over the photoresist film 102, as described above with respect to FIG. 2B .

[0054] In step 210, the substrate 100 is etched using the remaining portion of the photoresist film 102 (e.g., the exposed area 105) as a mask to form the opening 118, as described above with respect to Figure 3A. Subsequently, a conductive feature may be formed in the opening 118, as described above with respect to Figures 3B-3C.

[0055] FIG5 shows 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 photoresist) is formed over the substrate 100, as described above with respect to FIG1B . In step 304, the photoresist film 102 is exposed to a light pattern (e.g., an EUV light pattern 104), which forms a pattern of exposed regions 105 and unexposed regions 107 of the photoresist film 102, as described above with respect to FIG1C .

[0056] In step 306, the developing gas 122 and the selective gas 112 are simultaneously flowed over the photoresist film 102, as described above with respect to Figures 2A and 2B. In step 308, the substrate 100 is etched using the remaining portion of the photoresist film 102 (e.g., the exposed area 105) as a mask to form the opening 118, as described above with respect to Figure 3A. Subsequently, a conductive feature can be formed in the opening 118, as described above with respect to Figures 3B-3C.

[0057] FIG6 shows 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 photoresist) is formed over the substrate 100, as described above with respect to FIG1B . In step 404, the photoresist film 102 is exposed to a light pattern (e.g., an EUV light pattern 104), which forms a pattern of exposed regions 105 and unexposed regions 107 of the photoresist film 102, as described above with respect to FIG1C .

[0058] Steps 406 and 408 are one cycle of a cyclic development process performed on the photoresist film 102 in the process chamber. In step 406, the developing gas 122 is flowed over the photoresist film 102, as described above with respect to FIG. 2B . In step 408, the developing gas 122 is purged from the process chamber by flowing the selective gas 112, as described above with respect to FIG. 2A . In various embodiments, steps 406 and 408 may be repeated for a suitable number of cycles, for example, from 1 to 50 cycles. In some embodiments, the developing gas 122 is HBr, and the selective gas is BCl 3. In some embodiments, different developing gases 122 and / or different selective gases 112 may be used in different cycles of the cyclic development process.

[0059] In step 410, the substrate 100 is etched using the remaining portion of the photoresist film 102 (e.g., the exposed area 105) as a mask to form the opening 118, as described above with respect to Figure 3A. Subsequently, a conductive feature may be formed in the opening 118, as described above with respect to Figures 3B-3C.

[0060] FIG7 shows 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 photoresist) is formed over the substrate 100, as described above with respect to FIG1B . In step 504, the photoresist film 102 is exposed to a light pattern (e.g., an EUV light pattern 104), which forms a pattern of exposed regions 105 and unexposed regions 107 of the photoresist film 102, as described above with respect to FIG1C .

[0061] In step 506, a first selective gas 112 is flowed over the photoresist film 102, as described above with respect to FIG 2A. In some embodiments, the first selective gas 112 is water vapor, and step 506 is a processing step that increases the selectivity of the subsequent development step 508.

[0062] In step 508, the developing gas 122 and the second selective gas 112 are simultaneously flowed over the photoresist film 102, as described above with respect to Figures 2A and 2B. In some embodiments, the first selective gas 112 and the second selective gas 112 are the same gas. In another embodiment, the first selective gas 112 and the second selective gas 112 are different gases. For example, the first selective gas 112 may be BCl3, and the second selective gas 112 may be water vapor.

[0063] In step 510, the substrate 100 is etched using the remaining portion of the photoresist film 102 (e.g., the exposed area 105) as a mask to form the opening 118, as described above with respect to Figure 3A. Subsequently, a conductive feature may be formed in the opening 118, as described above with respect to Figures 3B-3C.

[0064] FIG8 shows 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 photoresist) is formed over the substrate 100, as described above with respect to FIG1B . In step 604, the photoresist film 102 is exposed to a light pattern (e.g., an EUV light pattern 104), which forms a pattern of exposed regions 105 and unexposed regions 107 of the photoresist film 102, as described above with respect to FIG1C .

[0065] In step 606, a first selective gas 112 is flowed over the photoresist film 102, as described above with respect to FIG 2A. In some embodiments, the first selective gas 112 is water vapor, and step 606 is a processing step that increases the selectivity of a subsequent development step 608.

[0066] Steps 608 and 610 are one cycle of a cyclic development process performed on the photoresist film 102 in the process chamber, as described above with respect to steps 406 and 408, respectively, shown in FIG6 . In step 608 , the developing gas 122 is flowed over the photoresist film 102 , as described above with respect to FIG2B . In step 610 , the developing gas 122 is purged from the process chamber by flowing the second selective gas 112 , as described above with respect to FIG2A . In various embodiments, steps 608 and 610 may be repeated for a suitable number of cycles, for example, from 1 to 50 cycles. In some embodiments, the first selective gas 112 and the second selective gas 112 are the same gas. In some embodiments, the first selective gas 112 and the second selective gas 112 are different gases.

[0067] In step 612, the substrate 100 is etched using the remaining portion of the photoresist film 102 (e.g., the exposed area 105) as a mask to form the opening 118, as described above with respect to Figure 3A. Subsequently, a conductive feature may be formed in the opening 118, as described above with respect to Figures 3B-3C.

[0068] FIG9 shows 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 photoresist) is formed over the substrate 100, as described above with respect to FIG1B . In step 704, the photoresist film 102 is exposed to a light pattern (e.g., an EUV light pattern 104), which forms a pattern of exposed regions 105 and unexposed regions 107 of the photoresist film 102, as described above with respect to FIG1C .

[0069] Steps 706 and 708 are one cycle of a cyclic development process performed on the photoresist film 102 in the process chamber. In step 706, the developing gas 122 and the first selective gas 112 are simultaneously flowed over the photoresist film 102, as described above with respect to Figures 2A and 2B. In step 708, the developing gas 122 is purged from the process chamber by flowing the second selective gas 112, as described above with respect to Figure 2A. In various embodiments, steps 706 and 708 may be repeated for a suitable number of cycles, for example, from 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.

[0070] In step 710, the substrate 100 is etched using the remaining portion of the photoresist film 102 (e.g., the exposed area 105) as a mask to form the opening 118, as described above with respect to Figure 3A. Subsequently, a conductive feature may be formed in the opening 118, as described above with respect to Figures 3B-3C.

[0071] FIG10 shows 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 photoresist) is formed over the substrate 100, as described above with respect to FIG1B . In step 804, the photoresist film 102 is exposed to a light pattern (e.g., an EUV light pattern 104), which forms a pattern of exposed regions 105 and unexposed regions 107 of the photoresist film 102, as described above with respect to FIG1C .

[0072] In step 806, a first selective gas 112 is flowed over the photoresist film 102, as described above with respect to FIG 2A. In some embodiments, the first selective gas 112 is water vapor, and step 806 is a processing step that increases the selectivity of the subsequent development step 808.

[0073] Steps 808 and 810 are one cycle of a cyclic development process performed on the photoresist film 102 in the process chamber. In step 808, the developing gas 122 and the second selective gas 112 are simultaneously flowed over the photoresist film 102, as described above with respect to Figures 2A and 2B. In step 810, the developing gas 122 is purged from the process chamber by flowing the third selective gas 112, as described above with respect to Figure 2A. In various embodiments, steps 806 and 810 may be repeated for a suitable number of cycles, for example, from 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.

[0074] In step 812, the substrate 100 is etched using the remaining portion of the photoresist film 102 (e.g., the exposed area 105) as a mask to form the opening 118, as described above with respect to Figure 3A. Subsequently, a conductive feature may be formed in the opening 118, as described above with respect to Figures 3B-3C.

[0075] FIG11 shows a process flow diagram of a method 900 for processing a substrate, according to some embodiments. In step 902, a substrate 100 having an exposed metal oxide photoresist 102 is received in a processing chamber, as described above with respect to FIG2A. The exposed metal oxide photoresist 102 includes exposed regions 105 and unexposed regions 107.

[0076] In step 904, a selective gas 112 is flowed over the exposed metal oxide photoresist, as described above with respect to FIG. 2A . The selective gas 112 increases the selectivity of the developing gas between the exposed regions 105 and the unexposed regions 107 of the exposed metal oxide photoresist 102. In step 906, a developing gas 122 is flowed over the exposed metal oxide photoresist 102 in the processing chamber, as described above with respect to FIG. 2B .

[0077] Illustrative embodiments of the present disclosure are summarized herein. Other embodiments are also available from this specification as a whole and from the claims of the applications filed herein.

[0078] Example 1. A method for processing a substrate, the method comprising: receiving a first substrate having an exposed metal oxide photoresist in a processing chamber, the exposed metal oxide photoresist comprising exposed portions and unexposed portions; flowing a selective gas over the exposed metal oxide photoresist, wherein the selective gas increases selectivity of a developing gas between the exposed portions and the unexposed portions of the exposed metal oxide photoresist; and flowing the developing gas over the exposed metal oxide photoresist in the processing chamber.

[0079] Example 2. The method of Example 1, wherein the selective gas comprises a hydroxyl group, an amine group, an organic carboxylic acid, or a Lewis acid.

[0080] Example 3. The method of Example 1, wherein the selective gas comprises water vapor, boron trichloride, chlorine, methanol, ethanol, isopropanol, acetylacetone, or acetic acid.

[0081] Example 4. The method of any one of Examples 1 to 3, wherein the exposed metal oxide photoresist comprises tin (Sn), antimony (Sb), hafnium (Hf), zirconium (Zr), or zinc (Zn).

[0082] Example 5. The method of any one of Examples 1 to 3, wherein the exposed metal oxide photoresist comprises a metal alkoxide or methacrylate (MAA) of Sn, Sb, Hf, Zr, or Zn.

[0083] Example 6. The method of any one of Examples 1 to 3, wherein the exposed metal oxide photoresist comprises a polymer film.

[0084] Example 7. The method of any one of Examples 1 to 3, wherein the exposed metal oxide photoresist comprises a metal and a group bonded to the metal, wherein the group is represented by a chemical formula selected from the group consisting of -OR, -OR', -OAr, and -OOCR, wherein R is an alkyl group, R' is an alkene group, and Ar is an aryl group.

[0085] Example 8. The method of any one of Examples 1 to 7, wherein the developing gas comprises hydrogen bromide (HBr) or hydrogen chloride (HCl).

[0086] Example 9. The method of any one of Examples 1 to 7, wherein the developing gas comprises acetic acid, trifluoroacetic acid, hexafluoroacetylacetone, acetylacetone, boron trichloride (BCl 3 ), or boron tribromide (BBr 3 ).

[0087] Example 10. A method for processing a substrate, the method comprising: forming a metal oxide photoresist over the substrate; exposing the metal oxide photoresist to a pattern of extreme ultraviolet light; flowing a first selective gas over the metal oxide photoresist in a processing chamber; after flowing the first selective gas, simultaneously flowing a developing gas and a second selective gas over the metal oxide photoresist in the processing chamber, wherein the developing gas includes an element that is not part of the first selective gas or the second selective gas; and etching the substrate using a remaining portion of the metal oxide photoresist as a mask.

[0088] Example 11. The method of Example 10, wherein the first selective gas and the second selective gas are the same gas.

[0089] Example 12. The method of Example 10, wherein the first selective gas and the second selective gas are different gases.

[0090] Example 13. The method of any one of Examples 1 to 12, wherein the first selective gas comprises boron trichloride.

[0091] Example 14. The method of any one of Examples 1 to 13, wherein the developing gas comprises hydrogen bromide and the second selective gas comprises water vapor.

[0092] Example 15. A method for processing a substrate, the method comprising: forming a metal oxide photoresist over the substrate; exposing the metal oxide photoresist to a pattern of extreme ultraviolet light; flowing a first developing gas over the metal oxide photoresist in a processing chamber; purging the first developing gas from the processing chamber using a first selective gas, the first selective gas having a different molecular structure than the first developing gas; after purging the first developing gas, flowing a second developing gas over the metal oxide photoresist in the processing chamber; and etching the substrate using a remaining portion of the metal oxide photoresist as a mask.

[0093] Example 16. The method of Example 15, wherein the first developing gas and the second developing gas are the same gas.

[0094] Example 17. The method of Example 16, wherein the same gas comprises hydrogen bromide.

[0095] Example 18. The method of any one of Examples 15 to 17, wherein the first selective gas comprises water vapor.

[0096] Example 19. The method of any one of Examples 15 to 18, wherein the first selective gas comprises boron trichloride.

[0097] Example 20. The method of any one of Examples 15 to 19, further comprising flowing a second selective gas over the metal oxide photoresist in the processing chamber before flowing the first developing gas, wherein the second selective gas increases a second selectivity of the exposed metal oxide photoresist to the first developing gas.

[0098] Although this disclosure has been described in detail, it should be understood that many changes, substitutions, and modifications may be made without departing from the spirit and scope of the disclosure as defined by the appended claims. In the various drawings, like elements are designated by like reference numerals. Furthermore, the scope of the disclosure is not intended to be limited to the specific embodiments described herein, as one skilled in the art will readily appreciate from this disclosure that processes, machines, manufacture, compositions of matter, tools, methods, or steps now existing or later developed may perform substantially the same functions or achieve substantially the same results as the corresponding embodiments described herein. Therefore, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, tools, methods, or steps.

[0099] 100:Substrate 101: conductive feature 102: Photoresist film, metal oxide photoresist 104: EUV light pattern 105: Exposed area 107: Unexposed area 108: Opening 112: Selective Gas 118: Open 122: Development gas 130: Conductive material 132: conductive feature 150: Intermetallic Dielectric 152: Wire 200:Method 202: Steps 204: Steps 206: Steps 208: Steps 210: Steps 300: Method 302: Steps 304: Steps 306: Steps 308: Steps 400:Method 402: Steps 404: Steps 406: Steps 408: Steps 410: Steps 500:Method 502: Steps 504: Steps 506: Steps 508: Steps 510: Steps 600:Method 602: Step 604: Steps 606: Steps 608: Steps 610: Steps 612: Steps 700: Method 702: Steps 704: Steps 706: Steps 708: Steps 710: Steps 800:Method 802: Step 804: Steps 806: Steps 808: Steps 810: Steps 812: Steps 900: Method 902: Steps 904: Steps 906: Steps

Claims

1. A method for processing a substrate, the method comprising: receiving a first substrate having an exposed metal oxide photoresist in a processing chamber, the exposed metal oxide photoresist comprising an exposed portion and an unexposed portion; flowing a selective gas over the exposed metal oxide photoresist, wherein the selective gas increases the selectivity of the exposed portion and the unexposed portion of the exposed metal oxide photoresist to a developing gas, the selective gas comprising boron trichloride (BCl3); and after flowing the selective gas, flowing the developing gas over the exposed metal oxide photoresist in the processing chamber.

2. The method for processing a substrate as claimed in claim 1, wherein the exposed metal oxide photoresist comprises tin (Sn), antimony (Sb), hafnium (Hf), zirconium (Zr), or zinc (Zn).

3. The method for processing a substrate as claimed in claim 1, wherein the exposed metal oxide photoresist comprises a metal alkoxide of Sn, Sb, Hf, Zr, or Zn or a methacrylate (MAA).

4. The method for processing a substrate as claimed in claim 1, wherein the exposed metal oxide photoresist comprises a polymer film.

5. The method for processing a substrate as claimed in claim 1, wherein the exposed metal oxide photoresist comprises a metal and a group bonded to the metal, wherein the group is represented by a chemical formula selected from the list of -OR, -OR', -OAr, and -OOCR, wherein R is an alkyl group, R' is an alkenyl group, and Ar is an aromatic group.

6. The method for processing a substrate as claimed in claim 1, wherein the developing gas contains hydrogen bromide (HBr) or hydrogen chloride (HCl).

7. The method for processing a substrate as claimed in claim 1, wherein the developing gas comprises acetic acid, trifluoroacetic acid, hexafluoroacetyl acetone, acetyl acetone, boron trichloride (BCl3), or boron tribromide (BBr3).

8. The method for processing a substrate as claimed in claim 1, wherein the selective gas and the developing gas flow simultaneously over the exposed metal oxide photoresist.

9. The method for processing a substrate as claimed in claim 1, wherein the selective gas is flowed to purge the developing gas from the processing chamber.

10. A method for processing a substrate, the method comprising: forming a metal oxide photoresist on the substrate; exposing the metal oxide photoresist to an extreme ultraviolet (EUV) pattern; flowing a first selective gas over the metal oxide photoresist in a processing chamber, the first selective gas comprising boron trichloride; after flowing the first selective gas, simultaneously flowing a developing gas and a second selective gas over the metal oxide photoresist in the processing chamber, wherein the developing gas comprises an element not part of either the first selective gas or the second selective gas; and etching the substrate using the remaining portion of the metal oxide photoresist as a mask.

11. The method for processing a substrate as claimed in claim 10, wherein the first selective gas and the second selective gas are the same gas.

12. The method for processing a substrate as claimed in claim 10, wherein the first selective gas and the second selective gas are different gases.

13. The method for processing a substrate as claimed in claim 10, wherein the developing gas contains hydrogen bromide and the second selective gas contains water vapor.

14. The method for processing a substrate as claimed in claim 10, wherein the first selective gas system is provided at a dose in the range of 5 sccm to 500 sccm.

15. A method for processing a substrate, the method comprising: forming a metal oxide photoresist on the substrate; exposing the metal oxide photoresist to an extreme ultraviolet (EUV) pattern; allowing a first developing gas to flow over the metal oxide photoresist in a processing chamber; purging the first developing gas from the processing chamber using a first selective gas having a molecular structure different from the first developing gas, the first selective gas comprising boron trichloride; after purging the first developing gas, allowing a second developing gas to flow over the metal oxide photoresist in the processing chamber; and etching the substrate using the remaining portion of the metal oxide photoresist as a mask.

16. The method for processing a substrate as claimed in claim 15, wherein the first developing gas and the second developing gas are the same gas.

17. The method for processing a substrate as claimed in claim 16, wherein the same gas comprises hydrogen bromide.

18. The method for processing a substrate as claimed in claim 15 further includes, before the first developing gas flows, flowing a second selective gas over the metal oxide photoresist in the processing chamber, wherein the second selective gas increases the selectivity of the exposed metal oxide photoresist to the first developing gas.

19. The method for processing a substrate as claimed in claim 15 further includes, while the second developing gas flows, causing the second selective gas to flow above the metal oxide photoresist in the processing chamber.

20. The method for processing a substrate as claimed in claim 19, wherein the second selective gas comprises water vapor.

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