Cyclic method for reactive development of photoresists

Abstract

A method for processing a substrate includes receiving the substrate, the substrate including a photoresist film, the photoresist film including exposed and unexposed portions; etching a portion of the unexposed portion of the photoresist film with a developing gas in a processing chamber to leave a residual portion of the unexposed portion; and purging the developing gas out of the processing chamber with a purge gas. After purging the developing gas, etching the residual portion of the unexposed portion with the developing gas. The exposed portion of the photoresist film is used 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 relates to methods of developing metal oxide resists for extreme ultraviolet (EUV) patterning. [Cross-reference to related applications]

[0002] This application claims the benefit of U.S. non-provisional patent application No. 17 / 888,135, filed on August 15, 2022, which is incorporated herein by reference. Prior Art

[0003] Photolithography is commonly used for patterning thin films during semiconductor processing, where photons are emitted from a light source onto a photosensitive photoresist, initiating a chemical reaction in the resist. The photoresist 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 enabled significant technological advancements, including advanced lithography techniques such as immersion lithography. Extreme ultraviolet (EUV) radiation can be used to improve pattern resolution in advanced integrated circuits, where reduced feature sizes are required. Common EUV photoresists are polymer-based chemically amplified resists (CARs), which are deposited on substrates using liquid spin-coating techniques and consume large amounts of complex precursors. Recently, inorganic-based resists have attracted interest because they can be patterned using EUV radiation and offer the high etch resistance and etch selectivity required for semiconductor manufacturing. However, the processing and development of inorganic-based resists present new challenges. Summary of the Invention

[0005] According to one embodiment, a method for processing a substrate includes: receiving a substrate, the substrate including a photoresist film, the photoresist film including exposed and unexposed portions; etching portions of the unexposed portions of the photoresist film with a developing gas in a processing chamber to leave residual portions of the unexposed portions; purging the developing gas out of the processing chamber with a purge gas; after purging the developing gas, etching the residual portions of the unexposed portions with the developing gas; and etching the substrate using the exposed portions of the photoresist film as a mask.

[0006] According to another embodiment, a method for patterning a photoresist film includes exposing the photoresist film to a pattern of extreme ultraviolet light, the photoresist film being located on a substrate; and performing a cyclic development process on the photoresist film in a processing chamber, wherein a first cycle of the cyclic development process includes flowing a developing gas in the processing chamber to etch unexposed portions of the photoresist film, and purging the developing gas from the processing chamber by flowing a purge gas.

[0007] According to yet another embodiment, a method of processing a substrate includes: forming a photoresist film on a substrate; exposing the photoresist film to a pattern of extreme ultraviolet light; flowing a developing gas at a first pressure to etch unexposed portions of the photoresist film; performing a first purge of the developing gas by flowing a purge gas; flowing the developing gas at a second pressure to further etch the unexposed portions of the photoresist film; and performing a second purge of the developing gas by flowing the purge gas.

[0008] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure as defined in the claims. Simple diagram description

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

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

[0011] Figures 2A-2C show example steps of a photoresist development process according to various embodiments;

[0012] Figures 3A-3D illustrate steps of an example manufacturing process for forming conductive features in and on a substrate according to various embodiments;

[0013] Figure 4 shows a process flow chart of a method for processing a substrate according to various embodiments;

[0014] Figure 5 shows a process flow chart of a method for patterning a photoresist film according to various embodiments;

[0015] FIG. 6 illustrates a process flow diagram of a method of processing a substrate according to various embodiments.

[0016] Unless otherwise indicated, corresponding numbers and symbols in the various figures generally refer to corresponding components. These figures are drawn to clearly illustrate the relevant aspects of the present embodiment and are not necessarily drawn to scale. The edges of features drawn in the figures do not necessarily represent the endpoints of the features. Implementation Method

[0017] The following sections discuss in detail the making and using of various embodiments. However, it should be understood that the various embodiments described herein are applicable to various specific situations. The specific embodiments discussed are merely illustrative of specific methods of making and using the various embodiments and should not be construed as limiting the scope.

[0018] According to one or more embodiments of the present disclosure, the present application relates to a method for developing inorganic resists (such as metal oxide resists) for EUV patterning. A developer gas is flowed into a processing chamber in a cyclic process, followed by a purge step. In various embodiments, the developer gas is provided at a constant pressure or a gradually increasing pressure in each step. The developer gas can be provided at the same temperature or at different temperatures in successive steps, thereby enabling the process temperature at the beginning and during the cyclic process to be different from the process temperature at the end of the cyclic process. The purge gas can be a non-reactive gas to purge the developer gas, a reactive gas to improve selectivity and development efficiency, or a combination thereof. This embodiment can improve the selectivity of the development etch and enhance the integrity of the development etch process, regardless of the desired opening aspect ratio. This embodiment allows for additional control over the development process. For example, process selectivity and roughness can be adjusted by selecting an appropriate purge gas chemistry.

[0019] Embodiments of the present disclosure are described with reference to the accompanying drawings. Figures 1A-1C illustrate an embodiment of an exemplary manufacturing process including the formation and exposure of an EUV-sensitive photoresist film. Figures 2A-2C illustrate an embodiment of an exemplary development process. Figures 3A-3D illustrate an embodiment of an exemplary manufacturing process for forming conductive features in and on a substrate. Figure 4 illustrates an embodiment of a method for processing a substrate. Figure 5 illustrates an embodiment of a method for patterning a photoresist film. Figure 6 illustrates an embodiment of a method for processing a substrate.

[0020] Figures 1A-1C illustrate steps in an exemplary manufacturing process, including the formation and exposure of an EUV-sensitive photoresist film. Figure 1A is 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, such as 150 mm, 200 mm, 300 mm, or 450 mm. In various embodiments, substrate 100 may be part of a semiconductor device or include a semiconductor device and may undergo multiple processing steps, such as conventional processing. Thus, substrate 100 may include semiconductor layers useful in various microelectronic devices. For example, a semiconductor structure may include substrate 100, with various device regions formed therein.

[0021] 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 carbon on silicon, and silicon or a silicon layer on an SOI substrate. In various embodiments, substrate 100 is 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.

[0022] Figure 1B shows a cross-sectional view of substrate 100 after a photoresist film 102 (e.g., a metal oxide resist) has been deposited thereon. In various embodiments, although not shown, substrate 100 may further include various layers useful for semiconductor device fabrication. In this disclosure, these layers may be collectively referred to as a portion of substrate 100. For example, in some embodiments, substrate 100 may include a dielectric layer comprising 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. Furthermore, substrate 100 may include a hard mask layer, which can be patterned in a subsequent etching process after EUV light patterning. 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.

[0023] In the example shown in FIG1B , a photoresist film 102 is formed on a substrate 100. Alternatively, the photoresist film 102 can be formed as part of a three-layer stack commonly used for photolithographic patterning. The three-layer stack can be used to create a pattern and transfer it to a hard mask, which is then transferred to a base layer, such as a dielectric layer of the substrate 100. In various embodiments, the multilayer stack includes a base layer and a photoresist film 102 overlying the base layer, serving as an EUV-sensitive photoresist. In one or more embodiments, the base layer comprises a carbon material (e.g., silicon carbide or silicon oxycarbide) and can be formed via spin coating or vapor deposition (e.g., CVD). The multilayer stack can further include an oxide layer (e.g., silicon oxide) or a nitride layer (e.g., titanium nitride or silicon nitride) on the base layer and the photoresist film 102. For simplicity, FIG1B only illustrates the photoresist film 102 deposited directly on the substrate 100. However, as described above, in various embodiments, any suitable multilayer structure may be present as part of the substrate 100.

[0024] In various embodiments, the photoresist film 102 comprises tin (Sn), antimony (Sb), hafnium (Hf), zirconium (Zr), zinc (Zn), or combinations thereof. In certain embodiments, the photoresist film 102 comprises a metal oxide, a metal alkoxide, or a methacrylate (MAA) of Sn, Sb, Hf, Zr, or Zn, such as ZrMAA, SbMAA, SbMAA:F, HfMAA, ZnMAA, and ZnMAA:F. In certain embodiments, the photoresist film 102 may be a metal oxide network comprising metal alkoxides, metal alkyloxides, metal aryloxides, or metal carboxylates. These metal-bonded groups are generally represented by the chemical formulas -OR, -OR', -OAr, and -OOCR, respectively, where R is an alkyl group, R' is an alkenyl group, and Ar is an aryl group. In some embodiments, the photoresist film 102 includes organometallic bonds, wherein organic R groups (e.g., groups with a carbon length of 1-10, saturated and unsaturated bonds, one or more aromatic groups, or the like, or combinations thereof) are directly bonded to a metal (e.g., tin). In various embodiments, the photoresist film 102 is a polymer film and may not have a highly ordered structure such as a crystal. The number of functional groups bonded to each metal atom may vary, ranging from 1 to 4. Deposition of the photoresist film 102 may be performed by dry or wet processes. In various embodiments, the photoresist film 102 may be deposited by a vapor deposition method, such as chemical vapor deposition (CVD), plasma-enhanced CVD (PECVD), atomic layer deposition (ALD), or plasma-enhanced ALD (PEALD).

[0025] In some embodiments, the deposition process of 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. Exposure to these precursors may be performed sequentially or simultaneously. In various embodiments, the deposition process may be an ALD or pseudo-ALD process and 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 to form an adsorption layer on the substrate 100, and then exposing the substrate 100 to an oxygen-containing precursor gas to react 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 processing chamber. Alternatively, spatially separating the exposure steps can be achieved by using multiple spatially separated sections within the processing chamber and transferring the substrate from one section to another. To further separate the exposure steps temporally, vapor deposition can further include evacuating, purging, or both evacuating and purging the processing chamber between exposure steps. These additional steps can help ensure that reactions occur only at the surface and not in the vapor phase. The ALD or pseudo-ALD method according to this embodiment may be particularly advantageous in achieving highly uniform layer-by-layer growth of the photoresist film 102.

[0026] In another embodiment, rather than using an ALD process, precursors may be provided simultaneously in the process chamber to grow the photoresist film 102. This embodiment has the advantage of enabling continuous 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 and on the surface.

[0027] In other embodiments, the photoresist film 102 can be deposited using a liquid deposition method that alternates exposures to a tin-containing precursor liquid and an oxygen-containing precursor liquid. The liquid deposition method 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, a common organic solvent such as acetone, propylene glycol monomethyl ether acetate, 1-methoxy-2-propanol, methyl isobutyl carbinol, n-hexane, tert-butyl alcohol, and isopropyl alcohol, or a mixture thereof. In another embodiment, the liquid precursors may be mixed and then the mixed solution may be applied to the substrate to grow the photoresist film 102. In one or more embodiments, one precursor may be gaseous and the other may be liquid, thereby enabling the deposition process to be performed using two different delivery modes (gas and liquid).

[0028] In various embodiments, after the photoresist film 102 is formed on the substrate 100, a post-coating bake may be performed to remove excess solvent from the wet process, residual volatile byproducts from the dry process, or both.

[0029] Figure 1C shows a cross-sectional view of the substrate 100 after exposure to a light pattern (e.g., EUV exposure). As shown in Figure 1C, the method further includes exposing the substrate 100 to an EUV light pattern 104. The EUV light pattern 104 can be created using a photomask placed between the substrate 100 and an EUV light source (not shown). In response to exposure to the EUV light pattern 104, exposed regions 105 of the photoresist film 102 may undergo a photoreaction, while unexposed regions 107 remain unchanged. As a result of the photoreaction, the exposed regions 105 may comprise a cross-linked photoresist film, which may have material properties substantially different from those of the unreacted portions of the photoresist film 102 (i.e., the unexposed regions 107). This difference in material properties, including volatility, reactivity, and / or solubility, creates the photoresist's tonality.

[0030] In various embodiments, an optional post-exposure bake (PEB) may be performed after the EUV exposure (see FIG. 1C above) and before the development step (see FIG. 2A below) to further differentiate the material properties between the exposed regions 105 and the unexposed regions 107. In certain embodiments, the PEB may be performed by heating the substrate 100 in a processing chamber under vacuum or airflow conditions at a temperature of 70° C. to 250° C., for example, 180° C. to 225° C. in one embodiment.

[0031] Figures 2A-2C illustrate steps in an exemplary cyclic development process (also known as a pulse process or pulse mode) for the photoresist film 102. This process may be performed after forming and exposing the photoresist film 102, as described above with respect to Figures 1A-1C. A cyclic development process is a reactive process at a gas-solid interface that, compared to wet processes, can achieve better process control at the nanometer scale, for example, for forming features with critical dimensions of a few nanometers or sub-nanometers. In some embodiments, the cyclic development process (also known as a cyclic reactive process) is a plasma-free process, such as a reactive sublimation process. In addition to developing the photoresist film 102, the cyclic reactive process can also be used as a resist stripping step to remove residues and defects on the photoresist film 102.

[0032] The cyclic development process includes multiple development steps, each separated by a respective purge step. During each development step, a development gas is flowed into the processing chamber containing the substrate 100 to partially etch the unexposed regions 107 of the photoresist film 102. A purge step is performed after the development step and before performing another development step. During the purge step, a purge gas is flowed into the processing chamber to purge the development gas. The purge gas can be a non-reactive gas (e.g., an inert gas) or a reactive gas, different from the development gas, that reacts with the unexposed regions 107. Following the purge step, another development step is performed to further etch the unexposed regions 107 of the photoresist film 102. The development and purge steps can be repeated any suitable number of times. Subsequent development steps can be performed at the same development gas pressure or at different pressures, for example, with the pressure gradually increasing with each additional development step. Subsequent development steps can be performed at the same processing chamber temperature or at different temperatures, such that the process temperature at the beginning of the cyclic development process is different from the process temperature at the end of the cyclic development process.

[0033] The cyclic development process improves the integrity of the development etch process, regardless of the desired opening aspect ratio, and also improves the selectivity of the development etch. The cyclic development process improves the integrity of the etch (in other words, removes more of the unexposed areas 107) while maintaining the selectivity of the etch (in other words, removes fewer of the exposed areas 105). This helps maintain the selectivity of the development etch at high temperatures (e.g., approximately 60°C). Furthermore, a given dose of developing gas develops more material from the unexposed areas 107 within a given feed time. This allows the development etch to be performed regardless of the aspect ratio of the opening formed through the photoresist film 102.

[0034] FIG2A , following FIG1C , illustrates a cross-sectional view of substrate 100 during a development step according to some embodiments. Substrate 100 is placed in a suitable processing chamber, and developing gas 110 flows into the processing chamber. Developing gas 110 reacts with unexposed regions 107 of photoresist film 102, producing volatile byproducts that then evaporate from the surface of substrate 100. This causes unexposed regions 107 to be recessed relative to exposed regions 105, forming openings 108 in photoresist film 102. In some embodiments, developing gas 110 is a reactive gas such as hydrogen bromide (HBr), hydrogen chloride (HCl), boron trichloride (BCl₃), an organic acid (e.g., a carboxylic acid), methanol, ethanol, isopropyl alcohol, or mixtures or combinations thereof. In some embodiments, different developing steps are performed using different developing gases 110. For example, hydrogen bromide may be used in the first development step, and boron trichloride may be used in the second development step.

[0035] The developing step may use a developing gas 110 flow rate ranging from 25 sccm to 1000 sccm. The developing step may be performed at a process chamber temperature ranging from -30°C to 120°C. The developing step may last from 1 second to 120 seconds.

[0036] The development step can be performed at a pressure in the processing chamber ranging from 5 mTorr to 100 mTorr. In some embodiments, each development step is performed at the same pressure, for example, 200 mTorr. In other embodiments, each successive development step is performed at a gradually increasing pressure. Each successive purge step (between successive development steps) can also be performed at a gradually increasing pressure. For example, the pressure can be gradually increased from 10 mTorr to 2 Torr every 5 to 10 seconds, with the pressure doubling with each increment.

[0037] In other embodiments, the developing step is performed under a gradually decreasing pressure, for example, the pressure is gradually decreased from 2 Torr to 10 mTorr every 5 to 10 seconds, with the pressure being halved each time.

[0038] In other embodiments, the development steps are performed alternately at lower and higher pressures. For example, one development step is performed at a pressure of 50 mTorr, a second development step is performed at a pressure of 300 mTorr, a third development step is performed at a pressure of 50 mTorr, and a fourth development step is performed at a pressure of 300 mTorr.

[0039] Successive development steps can be performed at a lower pressure for the preceding development step and a higher pressure for the following development step; at a higher pressure for the preceding development step and a lower pressure for the following development step; or at the same pressure for the preceding and following development steps. Any and all such arrangements of relative pressures between development steps fall within the scope of the disclosed embodiments.

[0040] FIG2B illustrates a cross-sectional view of substrate 100 during a purge step, according to some embodiments. The purge step is performed after the development step described above with respect to FIG2A . Following the development step, development gas 110 is purged from the processing chamber by flowing purge gas 120 . Each development step is followed by a purge step. A cyclic development process that performs sequential development and purge steps can help improve the integrity of the development etch process, regardless of the aspect ratio of opening 108 . A cyclic development process that employs purge steps between development steps can also improve the selectivity of the development etch by removing more unexposed areas 107 while removing fewer exposed areas 105 .

[0041] The purge step is accomplished by flowing a purge gas 120 into the processing chamber. The purge gas 120 can be a non-reactive (or inert) gas or a reactive gas. In embodiments where the purge gas 120 is a non-reactive gas, the purge gas can be argon (Ar), nitrogen (N2), carbon dioxide (CO2), or a combination thereof. In embodiments where the purge gas 120 is a reactive gas, the purge gas can be boron trichloride (BCl3), water vapor (H2O), chlorine (Cl2), ammonia (NH3), methanol, ethanol, trifluoroethanol, isopropyl alcohol, n-butanol, tert-butanol, nonafluoro-tert-butyl alcohol, ethylene glycol, acetylacetone, hexafluoroacetylacetone, an organic acid (e.g., acetic acid, trifluoroacetic acid, or the like), or a combination thereof. Using a reactive gas as the purge gas 120 allows for better control of etch selectivity under non-selective processing conditions, such as temperatures up to 250°C. For example, alternating between hydrogen bromide (HBr) as the developer gas 110 and a reactive purge gas 120 (e.g., boron trichloride (BCl₃)) during the development step can help improve selectivity and lithography efficiency. The selectivity and roughness of the development process can be adjusted by selecting appropriate chemistries (e.g., boron trichloride (BCl₃) or water vapor (H₂O)) for the purge gas. Subsequent purge steps can be performed at different pressures (e.g., gradually increasing pressure, gradually decreasing pressure, or alternating increasing and decreasing pressure). Subsequent purge steps can be performed using different gas flow rates (e.g., gradually increasing gas flow, gradually decreasing gas flow, or alternating increasing and decreasing gas flow). Subsequent purge steps can be performed for different purge durations.

[0042] In embodiments where the purge gas 120 is a non-reactive gas, the purge step may utilize a non-reactive gas at a flow rate in the range of 100 sccm to 2000 sccm. The purge step may be performed at a process chamber temperature in the range of -30°C to 250°C. The purge step may last for 5 to 60 seconds. The purge step may be performed at a pressure in the process chamber in the range of 1×10⁻³ mTorr to 1×10⁻³ mTorr.

[0043] In embodiments where the purge gas 120 is a reactive gas, the purge step may utilize a reactive gas flow rate in the range of 10 sccm to 500 sccm. The purge step may be performed in the process chamber at a temperature in the range of -30°C to 250°C. The purge step may last for 5 seconds to 120 seconds. The purge step may be performed in the process chamber at a pressure in the range of 1×10-1 mTorr to 1×10-3 mTorr.

[0044] In some embodiments, a cyclic development process includes a non-reactive purge step using a non-reactive gas and a reactive purge step using a reactive gas. As one example, the cyclic development process includes a first development step using hydrogen bromide (HBr), a first purge step using argon (Ar), a second development step using hydrogen bromide (HBr), and a second purge step using boron trichloride (BCl₃). As another example, the cyclic development process includes a first development step using hydrogen bromide (HBr), a first purge step using boron trichloride (BCl₃), a second development step using hydrogen bromide (HBr), and a second purge step using argon (Ar). Any and all such arrangements of non-reactive and reactive purge steps are within the scope of the disclosed embodiments.

[0045] In various embodiments, the development step described above in FIG. 2A and the purge step described above in FIG. 2B are repeated for a suitable number of cycles, where each cycle includes a development step followed by a purge step. For example, the development step and the purge step may be repeated for 1 to 60 cycles. However, any suitable number of development steps and purge steps may be used in any suitable order. For example, the first development step may be preceded by the first purge step, and the last purge step may be followed by the last development step.

[0046] FIG2C illustrates a cross-sectional view of substrate 100 after one or more development steps and one or more purge steps of a cyclic development process, according to some embodiments. After the cyclic development process, exposed regions 105 (see FIG1C-2B above) have been removed. Openings 108 extend through remaining unexposed regions 107 of photoresist film 102. Portions of the top surface of substrate 100 are exposed through openings 108. Unexposed regions 107 of photoresist film 102 can subsequently be used as a mask for etching substrate 100, for example, to form conductive features therein (see FIG3A-3C below). Embodiments of the cyclic development process can improve the completeness and selectivity of the development etch, regardless of the aspect ratio of openings 108, allowing substrate 100 to be exposed through openings 108 while retaining a sufficient amount of unexposed regions 107 for subsequent etching of substrate 100.

[0047] In the embodiment described in Figures 1A-2C above, the photoresist film 102 is a negative-tone photoresist. In other embodiments, the photoresist film 102 can be formed into a positive-tone photoresist, wherein the exposed regions 105 are removed by a development step, while the unexposed regions 107 remain. In one embodiment, the positive-tone photoresist can be achieved by performing an additional chemical treatment (e.g., polymerization) to improve the etch resistance of the unexposed regions 107 after EUV exposure, while the photoreaction in the exposed regions 105 reduces the etch resistance.

[0048] Figures 3A-3D illustrate cross-sectional views of intermediate steps in an exemplary fabrication process for forming conductive features within and on substrate 100. In Figure 3A, opening 108 is extended 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 a fluorine chemistry. However, any suitable etching process may be used. Exposed regions 105 of photoresist film 102 remain on substrate 100 and serve as a mask for the etching process. In some embodiments, opening 118 exposes the top surface of conductive feature 101 (e.g., a metal line) embedded in substrate 100.

[0049] In FIG3B , the exposed regions 105 of the photoresist film 102 are removed from the substrate 100, the etching and planarization residues are removed, and the conductive material 130 is formed on the substrate 100. The exposed regions 105 of the photoresist film 102 can be removed by a suitable process, such as a planarization process (e.g., CMP) or the like. In some embodiments, the etching and planarization residues can be removed by a suitable cleaning process, such as rinsing with deionized water, hydrogen peroxide, SC-1, or a combination thereof.

[0050] Still referring to FIG. 3B , a conductive material 130 is formed on substrate 100 to fill opening 118 (see FIG. 3A above). As an example of forming conductive material 130, a conformal barrier metal liner (e.g., TiN or TaN) is formed on the exposed surface of substrate 100. Next, opening 118 is filled with conductive material 130 (e.g., 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 forms electrical and physical contact with the top surface of conductive feature 101.

[0051] 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 a damascene conductive feature 132 in substrate 100. In various embodiments, conductive feature 132 is a high aspect ratio feature. Conductive feature 132 can be a conductive via that is physically and electrically coupled to conductive feature 101 of substrate 100.

[0052] In FIG3D , an interconnect layer is formed over substrate 100 and conductive features 132. The interconnect layer includes an intermetallic dielectric (IMD) 150, in which conductive lines 152 are formed. IMD 150 comprises an insulating material such as SiO 2 or a silicon oxide-based low-K dielectric (e.g., porous oxide, fluorosilicate glass (FSG), and orthosilicate glass (OSG)). In some embodiments, IMD 150 includes an underlying layer, or etch stop layer (ESL), comprising a dielectric such as Si 3 N 4 , SiO x N y , SiC, or SiCN (not shown). IMD 150 can be formed using a suitable process such as CVD.

[0053] Still referring to FIG3D , conductive lines 152 can be formed using a conventional damascene process, for example, 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 copper 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 damascened in 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).

[0054] FIG4 illustrates a process flow diagram of a method 200 for processing a substrate according to one embodiment. In step 202, a substrate 100 including a photoresist film 102 (e.g., a metal oxide resist) having exposed regions 105 and unexposed regions 107 is received into a processing chamber, as described above with respect to FIG2A .

[0055] In step 204, unexposed regions 107 of photoresist film 102 are etched using developer gas 110 in the processing chamber, leaving residual portions of unexposed regions 107, as described above with respect to FIG. 2A . In step 206, developer gas 110 is purged from the processing chamber using purge gas 120, as described above with respect to FIG. 2B . In step 208, the residual portions of unexposed regions 107 are further etched using developer gas 110, as described above with respect to FIG. 2A .

[0056] In step 210, the substrate 100 is etched to form the opening 118 using the exposed area 105 of the photoresist film 102 as a mask, 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.

[0057] 5 shows a process flow diagram of a method 300 for patterning photoresist according to some embodiments. In step 302, the photoresist film 102 on the substrate 100 is exposed to the EUV light pattern 104, as described above with respect to FIG. 1C.

[0058] Steps 304 and 306 are one cycle of a cyclic development process performed on photoresist film 102 in a processing chamber. In step 304, developing gas 110 is introduced to etch unexposed regions 107 of photoresist film 102, as described above with respect to FIG. 2A . In step 306, developing gas 110 is purged from the processing chamber by introducing purge gas 120, as described above with respect to FIG. 2B . In various embodiments, steps 304 and 306 are repeated for an appropriate number of cycles, for example, from one cycle to 60 cycles.

[0059] FIG6 illustrates 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 FIG1B . In step 404, the photoresist film 102 is exposed to a pattern of EUV light 104, forming a pattern of exposed regions 105 and unexposed regions 107 of the photoresist film 102, as described above with respect to FIG1C .

[0060] In step 406, the developer gas flows at a first pressure to etch the unexposed area 107 of the photoresist film 102, as described above with respect to FIG2A. In step 408, a first purge is performed to purge out the developer gas 110 with the purge gas 120, as described above with respect to FIG2B.

[0061] In step 410, the developer gas is flowed at a second pressure to further etch the unexposed regions 107 of the photoresist film 102, as described above with respect to FIG. 2A . In step 412, a second purge is performed to purge the developer gas 110 with the purge gas 120, as described above with respect to FIG. 2B . In some embodiments, steps 410 to 412 may be repeated additional times, for example, until the unexposed regions 107 are cleared. In some embodiments, the pressure of the developer gas is increased with each additional development step.

[0062] While exemplary embodiments of the present disclosure are summarized herein, other embodiments are contemplated within the scope of this specification and the claims presented herein.

[0063] Example 1. A method for processing a substrate, the method comprising: receiving a substrate, the substrate comprising a photoresist film, the photoresist film comprising exposed and unexposed portions; etching a portion of the unexposed portion of the photoresist film with a developing gas in a processing chamber to leave a residual portion of the unexposed portion; purging the developing gas out of the processing chamber with a purge gas; after purging the developing gas, etching the residual portion of the unexposed portion with the developing gas; and etching the substrate using the exposed portion of the photoresist film as a mask.

[0064] Example 2: The method of Example 1, wherein the developing gas comprises hydrogen bromide, hydrogen chloride, acetic acid, trifluoroacetic acid, trifluoroethanol, non-perfluoro tert-butyl alcohol, acetylacetone, or hexafluoroacetylacetone.

[0065] Example 3. The method of Example 1, wherein the developing gas comprises boron trichloride.

[0066] Example 4: A method as described in any one of Examples 1 to 3, wherein the purge gas comprises argon, nitrogen, boron trichloride or water vapor.

[0067] Example 5: A method as described in any one of Examples 1 to 4, wherein the unexposed portion is etched with a first pressure to leave a residual portion, and the residual portion of the unexposed portion is etched with a second pressure, and the second pressure is greater than the first pressure.

[0068] Example 6. A method as described in any one of Examples 1 to 5, wherein a portion of the unexposed portion is etched at a first temperature to leave a residual portion, and the residual portion of the unexposed portion is etched at a second temperature, and the second temperature is greater than the first temperature.

[0069] Example 7: The method of any one of Examples 1 to 6, wherein the photoresist film is a metal oxide resist.

[0070] Example 8. A method for patterning a photoresist film, the method comprising exposing the photoresist film to a pattern of extreme ultraviolet light, the photoresist film being located on a substrate; and performing a cyclic development process on the photoresist film in a processing chamber, wherein a first cycle of the cyclic development process comprises: flowing a developing gas in the processing chamber to etch unexposed portions of the photoresist film, and purging the developing gas from the processing chamber by flowing a purge gas.

[0071] Example 9. The method of Example 8, wherein the developing gas comprises hydrogen bromide.

[0072] Example 10. The method of Example 8 or 9, wherein the developing gas comprises boron trichloride.

[0073] Example 11. A method as described in any one of Examples 8 to 10, wherein a second cycle of the cyclic development process includes flowing a developing gas in the processing chamber to further etch unexposed portions of the photoresist film, wherein a pressure of the flowing developing gas in the second cycle is greater than a pressure of the flowing developing gas in the first cycle.

[0074] Example 12. A method as described in any one of Examples 8 to 10, wherein a second cycle of the cyclic development process includes flowing a developing gas in the processing chamber to further etch unexposed portions of the photoresist film, wherein the flowing of the developing gas in the second cycle is performed at the same pressure as the pressure of the flowing of the developing gas in the first cycle.

[0075] Example 13. A method as described in any one of Examples 8 to 12, wherein the purge gas is an inert gas.

[0076] Example 14. A method as described in any one of Examples 8 to 12, wherein the purge gas is boron trichloride or water vapor.

[0077] Example 15. A method for processing a substrate, the method comprising: forming a photoresist film on the substrate; exposing the photoresist film to a pattern of extreme ultraviolet light; flowing a developing gas at a first pressure to etch unexposed portions of the photoresist film; performing a first purge of the developing gas by flowing a purge gas; flowing the developing gas at a second pressure to further etch the unexposed portions of the photoresist film; and performing a second purge of the developing gas by flowing the purge gas.

[0078] Example 16. The method of Example 15, wherein the first pressure is the same as the second pressure.

[0079] Example 17. The method of Example 15, wherein the second pressure is greater than the first pressure.

[0080] Example 18. The method of Example 17 further includes flowing a developing gas at a third pressure to further etch unexposed portions of the photoresist film, wherein the third pressure is greater than the second pressure.

[0081] Example 19. The method of any one of Examples 15 to 18, wherein the developing gas comprises hydrogen bromide and the purge gas comprises boron trichloride.

[0082] Example 20. The method of any one of Examples 15 to 18, wherein the developing gas comprises boron trichloride and the purge gas comprises water vapor.

[0083] Although this specification has been described in detail, it should be understood that various changes, substitutions, and modifications may be made without departing from the spirit and scope of the present disclosure as defined by the appended claims. Like elements are denoted by like reference numerals throughout the various drawings. Furthermore, the scope of the present disclosure is not intended to be limited to the specific embodiments described herein, as one of ordinary skill in the art will readily appreciate from this disclosure that processes, machines, manufacture, compositions of matter, means, 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. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

[0084] 100:Substrate 101: conductive feature 102: Photoresist film 104: EUV light pattern 105: Exposure area 107: Unexposed area 108: Opening 110: Development gas 118: Open 120: Purge gas 130: Conductive material 132: conductive feature 150: Intermetallic Dielectric 152: Conductive thread 200:Method 202: Steps 204: Steps 206: Steps 208: Steps 210: Steps 300: Method 302: Steps 304: Steps 306: Steps 400:Method 402: Steps 404: Steps 406: Steps 408: Steps 410: Steps 412: Steps

Claims

1. A method for processing a substrate, the method comprising: receiving a substrate including a photoresist film, the photoresist film including exposed and unexposed portions; etching a portion of the unexposed portion of the photoresist film in a processing chamber using a developing gas to leave a residual portion of the unexposed portion; purging the developing gas out of the processing chamber using a first purge gas, the first purge gas being an inert gas; after purging the developing gas, etching the residual portion of the unexposed portion using the developing gas; purging the developing gas out of the processing chamber using a second purge gas, the second purge gas being a reactive gas; and using the exposed portion of the photoresist film as a mask to etch the substrate.

2. The method as described in claim 1, wherein the developing gas comprises hydrogen bromide, hydrogen chloride, acetic acid, trifluoroacetic acid, trifluoroethanol, non-perfluoro tert-butanol, acetoacetone, or hexafluoroacetoacetone.

3. The method as described in claim 1, wherein the developing gas contains boron trichloride.

4. The method as described in claim 1, wherein the first purging gas comprises argon, nitrogen, or carbon dioxide.

5. The method as described in claim 1, wherein etching the unexposed portion to leave the residual portion is performed under a first pressure, and etching the residual portion of the unexposed portion is performed under a second pressure, wherein the second pressure is greater than the first pressure.

6. The method as claimed in claim 1, wherein etching the unexposed portion to leave the residual portion is performed at a first temperature, and etching the residual portion of the unexposed portion is performed at a second temperature, wherein the second temperature is greater than the first temperature.

7. The method as described in claim 1, wherein the photoresist film is a metal oxide resist.

8. The method as described in claim 1, wherein the second purge gas is boron trichloride.

9. The method as described in claim 1, wherein the second purging gas is water vapor.

10. A method for patterning a photoresist film, the method comprising: exposing a photoresist film to a pattern of extreme ultraviolet light, the photoresist film being located on a substrate; and performing a cyclic development process on the photoresist film in a processing chamber, wherein a first cycle of the cyclic development process comprises: flowing a developing gas in the processing chamber to etch unexposed portions of the photoresist film, and purging the developing gas from the processing chamber by flowing a purge gas, wherein the purge gas is boron trichloride or water.

11. The method as described in claim 10, wherein the developing gas contains hydrogen bromide.

12. The method as described in claim 10, wherein the developing gas comprises boron trichloride.

13. The method of claim 10, wherein a second cycle of the cyclic development process includes flowing the developing gas in the processing chamber to further etch the unexposed portion of the photoresist film, wherein the pressure of the developing gas flowing in the second cycle is greater than the pressure of the developing gas flowing in the first cycle.

14. The method of claim 10, wherein a second cycle of the cyclic development process includes flowing the developing gas in the processing chamber to further etch the unexposed portion of the photoresist film, wherein the developing gas system is flowed in the second cycle at the same pressure as the developing gas flowed in the first cycle.

15. A method of processing a substrate, the method comprising: forming a photoresist film on a substrate; exposing the photoresist film to a pattern of extreme ultraviolet light; flowing a developing gas under a first pressure to etch unexposed portions of the photoresist film; performing a first purging of the developing gas by flowing a purge gas, the purge gas being reactive; flowing the developing gas under a second pressure to further etch the unexposed portions of the photoresist film; and performing a second purging of the developing gas by flowing the purge gas.

16. The method as described in claim 15, wherein the first pressure is the same as the second pressure.

17. The method as described in claim 15, wherein the second pressure is greater than the first pressure.

18. The method of claim 17 further comprises flowing a developing gas under a third pressure to further etch the unexposed portion of the photoresist film, wherein the third pressure is greater than the second pressure.

19. The method as claimed in claim 15, wherein the developing gas contains hydrogen bromide and the purging gas contains boron trichloride.

20. The method as claimed in claim 15, wherein the developing gas contains boron trichloride and the purging gas contains water vapor.

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