Cyclic method for reactive development of photoresists.

Abstract

A method for processing a substrate includes accommodating a substrate including a photoresist film including exposed and unexposed portions, etching a portion of the unexposed portions of the photoresist film with a developer gas in a processing chamber to leave a remaining portion of the unexposed portions, and purging the developer gas from the processing chamber with a purge gas. After purging the developer gas, the remaining portion of the unexposed portions is etched with the developer gas. The substrate is etched using the exposed portions of the photoresist film as a mask.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Non-Provisional Patent Application No. 17 / 888,135, filed August 15, 2022, which is incorporated herein by reference.

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

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

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

[0005] According to one embodiment, a method of processing a substrate includes: receiving a substrate including a photoresist film including exposed and unexposed portions; etching a portion of the unexposed portions of the photoresist film using a developer gas in a processing chamber to leave a remaining portion of the unexposed portions; purging the developer gas from the processing chamber using a purge gas; etching the remaining portion of the unexposed portions with the developer gas after purging the developer 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 a photoresist film on a substrate to a pattern of extreme ultraviolet light; and performing a repeated development process on the photoresist film in a processing chamber; wherein a first cycle of the repeated development process includes flowing a developer gas into the processing chamber to etch unexposed portions of the photoresist film, and purging the developer 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 the substrate; exposing the photoresist film to a pattern of extreme ultraviolet light; flowing a developer gas at a first pressure to etch unexposed portions of the photoresist film; performing a first purge of the developer gas by flowing a purge gas; flowing the developer gas at a second pressure to further etch unexposed portions of the photoresist film; and purging the developer gas a second time by flowing a purge gas.

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

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

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

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

[0012] The making and use of various embodiments are discussed in detail below. However, it should be recognized that the various embodiments described herein are applicable in a wide variety of specific situations. The specific embodiments discussed are merely illustrative of specific ways to make and use the various embodiments and should not be construed as limiting in scope.

[0013] According to one or more embodiments of the present disclosure, the present application relates to a method for developing inorganic resists (e.g., metal oxide resists) for EUV patterning. A developer gas is flowed into a processing chamber in a cyclic process, and a purge step follows the developer gas exposure. In various embodiments, the developer gas is supplied at a constant pressure or at a gradually increasing pressure in each step. The developer gas can be supplied at the same temperature, or at different temperatures in successive steps, such that the process temperature at the beginning and during the cyclic process is different from the process temperature at the end of the cyclic process. The purge gas can be a non-reactive gas for purging the developer gas, a reactive gas for improving selectivity and lithography efficiency, or a combination thereof. Some embodiments can increase the selectivity of the developer etch and improve the completeness of the developer etch process, regardless of the desired aspect ratio of the opening. Some embodiments can enable additional control of the development process. For example, the selectivity and roughness of the process can be adjusted by selecting the appropriate chemical for the purge gas.

[0014] Embodiments of the present disclosure are described in relation to the accompanying drawings. An embodiment of an exemplary manufacturing process including forming and exposing an EUV-sensitive photoresist film is described using FIGS. 1A-1C. An embodiment of an exemplary development process is described using FIGS. 2A-2C. An embodiment of an exemplary manufacturing process for forming conductive features in and on a substrate is described using FIGS. 3A-3D. An embodiment of a method for processing a substrate is described using FIG. 4. An embodiment of a method for patterning a photoresist film is described using FIG. 5. An embodiment of a method for processing a substrate is described using FIG. 6.

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

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

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

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

[0019] In various embodiments, the photoresist film 102 includes tin (Sn), antimony (Sb), hafnium (Hf), zirconium (Zr), zinc (Zn), or the like, or a combination thereof. In particular embodiments, the photoresist film 102 includes a metal oxide, metal alkoxide, or methacrylate (MAA) of a metal such as F, HfMAA, ZnMAA, and ZnMAA:Sn, Sb, Hf, Zr, or Zn, such as ZrMAA, SbMAA, SbMAA:F, HfMAA, ZnMAA, and ZnMAA:F. In particular embodiments, the photoresist film 102 can be a metal oxide network including metal alkoxide, metal alkene oxide, metal aryloxide, or metal carboxylate groups. These groups bonded to the metal are generally represented by the formulas -OR, -OR', -OAr, and -OOCR, respectively, where R is an alkyl group, R' is an alkene group, and Ar is an aryl group. In some embodiments, the photoresist film 102 comprises an organometallic bond in which an organic R group (e.g., a group having saturated and unsaturated bonds with a length of 1 to 10 carbons, one or more aromatic groups, etc., or a combination thereof) is 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 regular structure, such as a crystalline structure. The number of such functional groups bonded to a metal atom may vary from one metal atom to another and range from one to four. Deposition of the photoresist film 102 may be performed by a dry process or a wet process. In various embodiments, the photoresist film 102 may be deposited by vapor deposition, such as chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), or plasma enhanced ALD (PEALD).

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

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

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

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

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

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

[0026] 2A-2C illustrate steps in an exemplary cyclic development process (also referred to as a pulse process or pulse mode) of the photoresist film 102 that may be performed after forming and exposing the photoresist film 102, as described above with respect to FIGS. 1A-1C. The cyclic development process is a reactive process at the gas-solid interface that may enable greater process control at the nanoscale than wet processes, for example, for forming features with critical dimensions of several nanometers or sub-nanometers. In some embodiments, the cyclic development process (also referred to as a cyclic reactive process) is a plasmaless process, such as a reactive sublimation process. In addition to developing the photoresist film 102, the cyclic reactive process may also be used as a descum step to remove residue and defects from the photoresist film 102.

[0027] The cyclic development process includes multiple development steps separated by respective purge steps. In each development step, a developer gas is flowed into a 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 another development step is performed. In the purge step, a purge gas is flowed into the processing chamber to purge the developer gas. The purge gas may be a non-reactive gas (e.g., an inert gas) or a reactive gas different from the developer gas that reacts with the unexposed regions 107. After 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 may be performed with the same pressure of developer gas or at different pressures, such as gradually increasing pressures for each additional development step. Subsequent development steps may be performed at the same temperature in the processing chamber 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.

[0028] The repeated development process is advantageous for increasing the completeness of the development etching process and increasing the selectivity of the development etching, regardless of the aspect ratio of the desired opening. The repeated development process can maintain the selectivity of the etching (i.e., remove less of the exposed region 105) while increasing the completeness of the etching (i.e., remove more of the unexposed region 107). This is advantageous for maintaining the selectivity of the development etching at high temperatures, such as about 60°C. In addition, more material in the unexposed region 107 can be developed with a given developer gas exposure amount and a given exposure time. This allows the development etching to be completed regardless of the aspect ratio of the opening formed through the photoresist film 102.

[0029] FIG. 2A, continuing from FIG. 1C, illustrates a cross-sectional view of substrate 100 during a development step according to some embodiments. Substrate 100 is placed in a suitable process chamber, and developer gas 110 is flowed into the process chamber. The developer gas 110 reacts with unexposed regions 107 of photoresist film 102 to produce volatile by-products, which then evaporate from the surface of substrate 100. This causes unexposed regions 107 to become recessed relative to exposed regions 105, forming openings 108 in photoresist film 102. In some embodiments, developer gas 110 is a reactive gas such as hydrogen bromide (HBr), hydrogen chloride (HCl), boron trichloride (BCl), an organic acid (such as a carboxylic acid), methanol, ethanol, isopropyl alcohol, or a mixture or combination thereof. In some embodiments, different development steps are performed using different developer gases 110. For example, a first development step may be performed using hydrogen bromide, and a second development step may be performed using boron trichloride.

[0030] The developing step may be performed using a flow rate of the developing gas 110 ranging from 25 sccm to 1000 sccm. The developing step may be performed when the temperature in the processing chamber is in the range of −30° C. to 120° C. The developing step may be performed for a time period ranging from 1 second to 120 seconds.

[0031] The developing steps may be performed when the pressure in the processing chamber is in the range of 5 mTorr to 100 Torr. In some embodiments, each developing step is performed at the same pressure, e.g., 200 mTorr. In other embodiments, each successive developing step is performed at a gradually increasing pressure. Each successive purge step (between successive developing steps) may also be performed at a gradually increasing pressure. As an example, the pressure is gradually increased from 10 mTorr to 2 Torr every 5 to 10 seconds, doubling the pressure with each increase.

[0032] In yet another embodiment, the development step is performed at gradually decreasing pressures, for example, the pressure is gradually decreased from 2 Torr to 10 mTorr every 5 to 10 seconds, doubling the pressure with each increase.

[0033] In yet another embodiment, the developing steps are performed at alternating low and high pressures. As an example, a developing step is performed at a pressure of 50 mTorr, a second developing step is performed at a pressure of 300 mTorr, a third developing step is performed at a pressure of 50 mTorr, and a fourth developing step is performed at a pressure of 300 mTorr.

[0034] Successive development steps can be performed with a preceding development step at a lower pressure and a subsequent development step at a higher pressure, or with a preceding development step at a higher pressure and a subsequent development step at a lower pressure, or with the preceding and subsequent development steps at the same pressure, with all such configurations of relative pressures between development steps being within the scope of the disclosed embodiments.

[0035] FIG. 2B shows a cross-sectional view of substrate 100 during a purge step, according to some embodiments. The purge step occurs after the development step described above with respect to FIG. 2A. After the development step, the development gas 110 is purged from the processing chamber by flowing a purge gas 120. A purge step may occur after each development step. Performing a cyclic development process that includes successive development and purge steps may be useful to increase the integrity of the development etch process, regardless of the aspect ratio of opening 108. A cyclic development process that includes a purge step between development steps may also increase the selectivity of the development etch by removing more of unexposed regions 107 while removing less of exposed regions 105.

[0036] The purge step is performed by flowing a purge gas 120, which may be a non-reactive (or inert) gas or a reactive gas, into the processing chamber. In embodiments where the purge gas 120 is a non-reactive gas, the purge gas may be argon (Ar), nitrogen (N), carbon dioxide (CO), or the like, or a combination thereof. In embodiments where the purge gas 120 is a reactive gas, the purge gas may be boron trichloride (BC1), water vapor (HO), chlorine (Cl), ammonia (NH), 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, etc.), or a combination thereof. Using a reactive gas for the purge gas 120 may provide better control over etch selectivity under non-selective process conditions, such as temperatures up to 250°C. For example, alternating the use of a reactive purge gas 120 such as boron trichloride (BCl) with hydrogen bromide (HBr) as the development gas 110 in the development step can help improve selectivity and lithography efficiency. The selectivity and roughness of the development process can be adjusted by selecting an appropriate chemical for the purge gas (e.g., boron trichloride (BCl) or water vapor (H2O)). Subsequent purge steps may be performed at different pressures (e.g., gradually increasing pressure, gradually decreasing pressure, or alternating increasing and decreasing pressure). Subsequent purge steps may be performed at different gas flow rates (e.g., gradually increasing gas flow rate, gradually decreasing gas flow rate, or alternating increasing and decreasing gas flow rate). Subsequent purge steps may be performed for different purge times.

[0037] In embodiments where the purge gas 120 is a non-reactive gas, the purge step can be performed using a flow rate of the non-reactive gas ranging from 100 sccm to 2000 sccm. The purge step can be performed when the temperature within the processing chamber is in the range of -30°C to 250°C. The purge step can be performed for a time period ranging from 5 seconds to 60 seconds. The purge step can be performed when the pressure within the processing chamber is in the range of 1×10 -3 mTorr ~ 1 × 10 3 This can be done when the pressure is in the mTorr range.

[0038] In embodiments where the purge gas 120 is a reactive gas, the purge step may be performed using a flow rate of the reactive gas ranging from 10 sccm to 500 sccm. The purge step may be performed when the temperature within the processing chamber is in the range of -30°C to 250°C. The purge step may be performed for a time period ranging from 5 seconds to 120 seconds. The purge step may be performed when the pressure within the processing chamber is in the range of 1×10 -1 mTorr ~ 1 × 10 3 This can be done when the pressure is in the mTorr range.

[0039] In some embodiments, the cyclic development process includes a non-reactive purge step with a non-reactive gas and a reactive purge step with a reactive gas. As an example, the cyclic development process includes a first development step with hydrogen bromide (HBr), a first purge step with argon (Ar), a second development step with hydrogen bromide (HBr), and a second purge step with boron trichloride (BCl). As another example, the cyclic development process includes a first development step with hydrogen bromide (HBr), a first purge step with boron trichloride (BCl), a second development step with hydrogen bromide (HBr), and a second purge step with argon (Ar). All such configurations of non-reactive purge steps and reactive purge steps are within the scope of the disclosed embodiments.

[0040] In various embodiments, the developing step described above with respect to FIG. 2A and the purging step described above with respect to FIG. 2B are repeated for a suitable number of cycles, with each cycle including a developing step followed by a purging step. For example, the developing and purging steps may be repeated from 1 cycle to 60 cycles. However, any suitable number of developing and purging steps may be used in any suitable order. For example, a first developing step may be preceded by a first purging step, and a final developing step may follow a final purging step.

[0041] FIG. 2C 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 FIGS. 1C-2B, above) have been removed. Openings 108 extend through the remaining unexposed regions 107 of photoresist film 102. A portion of the top surface of substrate 100 is exposed through openings 108. The unexposed regions 107 of photoresist film 102 can then be used as a mask to etch substrate 100, for example, to form conductive features in substrate 100 (see FIGS. 3A-3C, below). In embodiments of the cyclic development process, the completeness and selectivity of the development etch can be increased, regardless of the aspect ratio of openings 108, such that substrate 100 is exposed by openings 108 while a sufficient amount of unexposed regions 107 remains for subsequent etching of substrate 100.

[0042] 1A-2C, the photoresist film 102 is a negative-tone photoresist. In another embodiment, the photoresist film 102 may form a positive-tone photoresist, in which the exposed regions 105 may be removed by a development step, leaving the unexposed regions 107. In one embodiment, a positive-tone photoresist may be enabled by performing an additional chemical treatment, such as polymerization, to increase the etch resistance of the unexposed regions 107 after EUV exposure, while a photochemical reaction in the exposed regions 105 reduces the etch resistance.

[0043] 3A-3D illustrate cross-sectional views of intermediate steps in an exemplary fabrication process for forming conductive features in and on substrate 100. In FIG. 3A, opening 108 is extended into substrate 100 to form opening 118 using a suitable anisotropic etching technique, such as a reactive ion etching (RIE) process using fluorine chemistry or an atomic layer etching (ALE) process. However, any suitable etching process may be used. Exposed regions 105 of photoresist film 102 remain on substrate 100 and act as a mask for the etching process. In some embodiments, opening 118 exposes a top surface of conductive feature 101 (e.g., a metal line) embedded in substrate 100.

[0044] 3B, exposed regions 105 of photoresist film 102 are removed from over substrate 100, residue from the etching and planarization processes is removed, and conductive material 130 is formed on substrate 100. Exposed regions 105 of photoresist film 102 may be removed using an appropriate process, such as a planarization process (e.g., CMP). In some embodiments, residue from the etching and planarization processes is removed using a suitable cleaning process, such as rinsing with deionized water, hydrogen peroxide, SC-1, or the like, or a combination thereof.

[0045] 3B, a conductive material 130 is formed on the substrate 100 to fill the opening 118 (see FIG. 3A, above). As an example of forming the conductive material 130, a conformal barrier metal (e.g., TiN or TaN) liner is formed on the exposed surface of the substrate 100. The opening 118 is then filled with the conductive material 130, such as a metal. For example, the conductive material 130 may be copper formed using electroplating. However, any suitable conductive material and deposition method may be used. In some embodiments, the conductive material 130 is in electrical and physical contact with the top surface of the conductive feature 101.

[0046] 3C, 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 various embodiments, conductive features 132 are high aspect ratio features. Conductive features 132 may be conductive vias that physically and electrically couple with conductive features 101 of substrate 100.

[0047] 3D, an interconnect layer is formed over the substrate 100 and the conductive features 132. The interconnect layer includes an inter-metal dielectric (IMD) 150 having conductive lines 152 formed therein. The IMD 150 includes an insulating material such as SiO2 or a silicon oxide-based low-k dielectric (e.g., porous oxide, fluorosilicate glass (FSG), and orthosilicate glass (OSG)). In some embodiments, the IMD 150 includes a material such as Si3N4, SiO x N y , SiC, or SiCN, or other suitable dielectric layers. The IMD 150 may be formed by a suitable process, such as CVD.

[0048] 3D , the conductive lines 152 may be formed by a conventional damascene process using a conductive material such as copper. As is well known to those skilled in the art, a damascene process includes patterning an opening (e.g., a trench for the conductive line 152) in the IMD 150, depositing a conformal barrier metal (e.g., TiN or TaN) liner, filling the opening with metal (e.g., using Cu electroplating), and removing any excess conductive material from the top surface of the IMD 150 using a planarization process such as chemical mechanical planarization (CMP), thereby forming the conductive lines 152 embedded in the IMD 150. In some embodiments, each conductive line 152 is formed to electrically and physically couple to one or more underlying conductive features 132 (e.g., conductive vias).

[0049] 4 shows a process flow diagram of a method 200 for processing a substrate, according to some embodiments. In step 202, a substrate 100 including a photoresist film 102 (e.g., metal oxide resist) having exposed regions 105 and unexposed regions 107, as described above with respect to FIG. 2A, is placed in a processing chamber.

[0050] In step 204, as described above with respect to Figure 2A, the unexposed regions 107 of the photoresist film 102 are etched in the process chamber with developer gas 110, leaving behind remaining portions of the unexposed regions 107. In step 206, as described above with respect to Figure 2B, the developer gas 110 is purged from the process chamber using purge gas 120. In step 208, as described above with respect to Figure 2A, the remaining portions of the unexposed regions 107 are further etched with developer gas 110.

[0051] In step 210, as described above with respect to Figure 3A, the substrate 100 is etched using the exposed regions 105 of the photoresist film 102 as a mask to form openings 118. Conductive features may then be formed in the openings 118, as described above with respect to Figures 3B-3C.

[0052] 5 is a process flow diagram of a method 300 for patterning photoresist according to some embodiments. In step 302, a photoresist film 102 on a substrate 100 is exposed to an EUV light pattern 104, as described above with respect to FIG. 1C.

[0053] Steps 304 and 306 are one cycle of a repeating development process performed in a processing chamber on the photoresist film 102. In step 304, as described above with respect to FIG. 2A, developer gas 110 is flowed to etch the unexposed portions 107 of the photoresist film 102. In step 306, as described above with respect to FIG. 2B, developer gas 110 is purged from the processing chamber by flowing purge gas 120. In various embodiments, steps 304 and 306 are repeated for a suitable number of cycles, such as 1 to 60 cycles.

[0054] 6 is a process flow diagram of a method 400 for processing a substrate, according to some embodiments. In step 402, a photoresist film 102 (e.g., a metal oxide resist) is formed on a substrate 100, as described above with respect to FIG. 1B. In step 404, the photoresist film 102 is exposed to an EUV light pattern 104, thereby forming a pattern of exposed regions 105 and unexposed regions 107 in the photoresist film 102, as described above with respect to FIG. 1C.

[0055] In step 406, as described above with respect to Figure 2A, a developer gas is flowed at a first pressure to etch unexposed areas 107 of photoresist film 102. In step 408, as described above with respect to Figure 2B, a first purge is performed in which developer gas 110 is purged with purge gas 120.

[0056] In step 410, 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 Figure 2A. In step 412, a second purge is performed, purging developer gas 110 with purge gas 120, as described above with respect to Figure 2B. In some embodiments, steps 410 through 412 may then be repeated for additional cycles, such as until the unexposed regions 107 are removed. In some embodiments, the pressure of the developer gas is increased for each additional development step.

[0057]

[0030] Exemplary embodiments of the present disclosure are summarized here. Other embodiments may be understood from the claims of this application, as well as from the entire specification. [Example]

[0058] Example 1. A method of processing a substrate, the method comprising: receiving a substrate including a photoresist film including exposed and unexposed portions; etching a portion of the unexposed portions of the photoresist film with a developer gas in a processing chamber to leave a remaining portion of the unexposed portions; purging the developer gas from the processing chamber with a purge gas; etching the remaining portion of the unexposed portions with the developer gas after purging the developer gas; and etching the substrate using the exposed portions of the photoresist film as a mask.

[0059] Example 2. The method of example 1, wherein the developing gas comprises hydrogen bromide, hydrogen chloride, acetic acid, trifluoroacetic acid, trifluoroethanol, nonafluoro-tert-butyl alcohol, acetylacetone, or hexafluoroacetylacetone.

[0060] Example 3. The method of example 1, wherein the developing gas comprises boron trichloride.

[0061] Example 4. The method of any one of Examples 1-3, wherein the purge gas comprises argon, nitrogen, boron trichloride, or water vapor.

[0062] Example 5. The method of any one of Examples 1-4, wherein etching a portion of the unexposed portion to leave a remaining portion is performed at a first pressure, and etching the remaining portion of the unexposed portion is performed at a second pressure, the second pressure being greater than the first pressure.

[0063] Example 6. The method of any one of Examples 1-5, wherein etching a portion of the unexposed portion to leave a remaining portion is performed at a first temperature, and etching the remaining portion of the unexposed portion is performed at a second temperature, the second temperature being greater than the first temperature.

[0064] Example 7. The method of any one of Examples 1-6, wherein the photoresist film is a metal oxide resist.

[0065] Example 8. A method for patterning a photoresist film, comprising: exposing a photoresist film on a substrate to a pattern of extreme ultraviolet light; and subjecting the photoresist film to a repeated development process in a processing chamber; wherein a first cycle of the repeated development process comprises flowing a developer gas into the processing chamber to etch unexposed portions of the photoresist film, and purging the developer gas from the processing chamber by flowing a purge gas.

[0066] Example 9. The method of Example 8, wherein the developing gas comprises hydrogen bromide.

[0067] Example 10. The method of example 8 or 9, wherein the developing gas comprises boron trichloride.

[0068] Example 11. The method of any one of Examples 8-10, wherein a second cycle of the repeated development process includes flowing a developer gas into the processing chamber to further etch unexposed portions of the photoresist film, and wherein the flowing of the developer gas in the second cycle is performed at a pressure higher than the pressure at which the developer gas is flowed in the first cycle.

[0069] Example 12. The method of any one of Examples 8-10, wherein a second cycle of the repeated development process includes flowing a developer gas into the processing chamber to further etch unexposed portions of the photoresist film, and wherein the flowing of the developer gas in the second cycle is performed at the same pressure as the pressure at which the developer gas is flowed in the first cycle.

[0070] Example 13. The method of any one of Examples 8-12, wherein the purge gas is an inert gas.

[0071] Example 14. The method of any one of Examples 8-12, wherein the purge gas is boron trichloride or water vapor.

[0072] Example 15. A method for treating 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 developer gas at a first pressure to etch unexposed portions of the photoresist film; performing a first purge of the developer gas by flowing a purge gas; flowing the developer gas at a second pressure to further etch unexposed portions of the photoresist film; and flowing a purge gas to purge the developer gas a second time.

[0073] Example 16. The method of example 15, wherein the first pressure is the same as the second pressure.

[0074] Example 17. The method of example 15, wherein the second pressure is greater than the first pressure.

[0075] Example 18. The method of Example 17, further comprising flowing a developer gas at a third pressure to further etch the unexposed portions of the photoresist film, the third pressure being greater than the second pressure.

[0076] Example 19. The method of any one of Examples 15-18, wherein the developing gas comprises hydrogen bromide and the purge gas comprises boron trichloride.

[0077] Example 20. The method of any one of Examples 15-18, wherein the developing gas comprises boron trichloride and the purge gas comprises water vapor.

[0078] Although described in detail herein, it should be understood that various changes, substitutions, and alterations can be made therein without departing from the spirit and scope of the present disclosure, as defined by the appended claims. In the various figures, like elements are designated with like reference numerals. Moreover, the scope of the present disclosure is not intended to be limited to the particular embodiments described herein; those skilled in the art will readily recognize from this disclosure that any now-existing or later-developed process, machine, manufacture, composition of matter, means, method, or step can perform substantially the same function or achieve substantially the same result as the corresponding embodiment described herein. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims

1. 1. A method of processing a substrate, comprising: accommodating a substrate having a photoresist film including exposed and unexposed portions; etching a portion of the unexposed portion of the photoresist film using a developer gas in a processing chamber to leave a remaining portion of the unexposed portion; purging the developing gas from the processing chamber with a purge gas; After the step of purging the developing gas, etching the remaining portion of the unexposed area with the developing gas; etching the substrate using the exposed portion of the photoresist film as a mask; A method comprising:

2. 2. The method of claim 1, wherein the developer gas comprises hydrogen bromide, hydrogen chloride, acetic acid, trifluoroacetic acid, trifluoroethanol, nonafluoro-tert-butyl alcohol, acetylacetone, or hexafluoroacetylacetone.

3. 10. The method of claim 1, wherein the developing gas comprises boron trichloride.

4. The method of claim 1 , wherein the purge gas comprises argon, nitrogen, boron trichloride, or water vapor.

5. 2. The method of claim 1, wherein etching a portion of the unexposed portion to leave the remaining portion is performed at a first pressure, and etching the remaining portion of the unexposed portion is performed at a second pressure, the second pressure being greater than the first pressure.

6. 2. The method of claim 1, wherein etching a portion of the unexposed portion to leave the remaining portion is performed at a first temperature, and etching the remaining portion of the unexposed portion is performed at a second temperature, the second temperature being higher than the first temperature.

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

8. 1. A method for patterning a photoresist film, comprising: exposing a photoresist film to a pattern of extreme ultraviolet light, the photoresist film being on a substrate; performing a repeated development process on the photoresist film in a processing chamber; and The first cycle of the repeated development process comprises: flowing a developer gas into the processing chamber to etch unexposed portions of the photoresist film; purging the developing gas from the processing chamber by flowing a purge gas; A method comprising:

9. 9. The method of claim 8, wherein the developing gas comprises hydrogen bromide.

10. 9. The method of claim 8, wherein the developer gas comprises boron trichloride.

11. a second cycle of the repeated development process comprising flowing the developer gas through the processing chamber to further etch unexposed portions of the photoresist film; 9. The method of claim 8, wherein the step of flowing the developer gas in the second cycle is carried out at a pressure higher than the pressure in the step of flowing the developer gas in the first cycle.

12. a second cycle of the repeated development process comprising flowing the developer gas through the processing chamber to further etch unexposed portions of the photoresist film; 9. The method of claim 8, wherein the step of flowing the developer gas in the second cycle is carried out at the same pressure as the step of flowing the developer gas in the first cycle.

13. The method of claim 8 , wherein the purge gas is an inert gas.

14. The method of claim 8 , wherein the purge gas is boron trichloride or water vapor.

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

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

17. The method of claim 15 , wherein the second pressure is greater than the first pressure.

18. and further etching the unexposed portion of the photoresist film by flowing a developing gas at a third pressure.

18. The method of claim 17, wherein the third pressure is greater than the second pressure.

19. 16. The method of claim 15, wherein the developer gas comprises hydrogen bromide and the purge gas comprises boron trichloride.

20. 16. The method of claim 15, wherein the developer gas comprises boron trichloride and the purge gas comprises water vapor.

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