Circulating method for reactive development of photoresist

Abstract

A method of processing a substrate includes receiving a substrate, the substrate including a photoresist film, the photoresist film including exposed and unexposed portions; etching an unexposed portion of a portion of the photoresist film with a developing gas in the 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 the developing gas is purged out, a remaining portion of the unexposed portion is etched with the developing gas. The substrate is etched using the exposed portion of the photoresist film as a mask.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Non-Provisional Application No. 17 / 888,135, filed on August 15, 2022, which is incorporated herein by reference. Technical Field

[0003] The present invention relates generally to the fields of semiconductor manufacturing and semiconductor devices, and in a particular embodiment to a method of developing metal oxide resists for extreme ultraviolet (EUV) patterning. Background Art

[0004] Photolithography is commonly used to pattern thin films during semiconductor processing, where photons are emitted from a light source onto a light-sensitive photoresist to induce a chemical reaction in the photoresist. The photoresist is then developed and the exposed or unexposed portions of the photoresist are removed to form a pattern or mask.

[0005] Scaling of semiconductor devices has enabled significant technological advances, including advanced lithography techniques such as immersion lithography. In advanced integrated circuits where reduced feature sizes are required, extreme ultraviolet (EUV) radiation can be used to improve pattern resolution. Common EUV photoresists are polymer-based chemically amplified resists (CARs) that are deposited on substrates using liquid spin coating techniques and require the consumption of large amounts of complex precursors. Recently, inorganic-based resists have attracted interest because they can be patterned using EUV radiation and can provide the high resistance and etch selectivity required for semiconductor manufacturing. However, the processing and development of inorganic-based resists face new challenges. Summary of the invention

[0006] According to one embodiment, a method for processing a substrate includes: 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 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.

[0007] According to another embodiment, a method of 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 subjecting the photoresist film to a cyclic development process 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.

[0008] 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 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.

[0009] 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 disclosure, as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] For a more complete understanding of the present invention and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, in which:

[0011] Figures 1A-1C illustrates steps of an exemplary manufacturing process for forming and exposing a photoresist according to various embodiments;

[0012] Figures 2A-2C illustrates steps of an exemplary development process of a photoresist according to various embodiments;

[0013] Figures 3A-3D Steps of an exemplary manufacturing process for forming conductive features in and on a substrate according to various embodiments are shown;

[0014] Figure 4 A process flow chart illustrating a method of processing a substrate according to various embodiments is shown;

[0015] Figure 5 A process flow diagram illustrating a method of patterning a photoresist film according to various embodiments; and

[0016] Figure 6 A process flow diagram illustrating a method of processing a substrate according to various embodiments is shown.

[0017] Unless otherwise indicated, corresponding numbers and symbols in different figures generally refer to corresponding elements. These figures are drawn to clearly show the relevant aspects of the embodiments, and these figures are not necessarily drawn to scale. The edges of features drawn in the figures do not necessarily indicate the end of the range of the features. DETAILED DESCRIPTION

[0018] The making and use of various embodiments are discussed in detail below. However, it should be understood that the various embodiments described herein can be applied to a wide variety of specific situations. The specific embodiments discussed are merely illustrations of specific ways to make and use the various embodiments, and should not be construed as limiting the scope.

[0019] 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. The developing gas flows into the processing chamber in a cyclic process, and the developing gas feeding is followed by a purging step. In various embodiments, the developing gas is provided at a constant pressure or a gradually increasing pressure in each step. The developing gas may be provided at the same temperature or at different temperatures in consecutive steps, so that the processing temperature at the beginning of the cyclic process and during the cyclic process is different from the processing temperature at the end of the cyclic process. The purging gas may be a non-reactive gas to purge the developing gas, a reactive gas to improve the selectivity and the development efficiency, or a combination thereof. The embodiments may improve the selectivity of the developing etching, and improve the integrity of the developing etching process, regardless of the depth-to-width ratio of the desired opening. The embodiments may allow additional control over the developing process. For example, the selectivity and roughness of the process may be adjusted by selecting appropriate chemicals for the purging gas.

[0020] Embodiments of the present disclosure will be described in conjunction with the accompanying drawings. Figures 1A-1C An embodiment of an exemplary manufacturing process including formation and exposure of an EUV-sensitive photoresist film will be described. Figures 2A-2C An example of an exemplary development process will be described. Figures 3A-3D Embodiments of exemplary fabrication processes for forming conductive features in and on a substrate will be described. Figure 4 An embodiment of a method of processing a substrate will be described. Figure 5 An embodiment of a method of patterning a photoresist film will be described. Figure 6 An embodiment of a substrate processing method will be described.

[0021] Figures 1A-1C Steps of an exemplary manufacturing process including formation and exposure of an EUV-sensitive photoresist film are shown. Figure 1A1 is a cross-sectional view of an exemplary substrate 100 to be patterned. For example, the substrate 100 may be a silicon wafer having a diameter in the range of 100 mm to 500 mm, such as a silicon wafer having a diameter of 150 mm, 200 mm, 300 mm, or 450 mm. In various embodiments, the substrate 100 may be a part of a semiconductor device, or include a semiconductor device, and may undergo multiple processing steps such as conventional processing. Thus, the substrate 100 may include semiconductor layers useful in various microelectronic devices. For example, a semiconductor structure may include the substrate 100, and various device regions may be formed in the substrate 100.

[0022] In one or more embodiments, the substrate 100 may be a silicon wafer or a silicon-on-insulator (SOI) wafer. In some embodiments, the substrate 100 may include silicon germanium, silicon carbide, gallium arsenide, gallium nitride, or other compound semiconductors. In other embodiments, the substrate 100 includes a heterogeneous layer, such as silicon germanium on silicon, gallium nitride on silicon, silicon carbon on silicon, and a silicon layer on a silicon or SOI substrate. In various embodiments, the substrate 100 is patterned or embedded in other components of the semiconductor device. In some embodiments, the substrate 100 includes a conductive feature 101 (such as a metal line) embedded therein. The conductive feature 101 can be electrically coupled to an active device (not shown) further embedded in the substrate 100.

[0023] Figure 1B A cross-sectional view of the substrate 100 after a photoresist film 102 (e.g., a metal oxide resist) is deposited on the substrate 100 is shown. In various embodiments, although not shown, the substrate 100 may further include various layers that can be used for semiconductor device manufacturing, which layers may be collectively referred to as a part of the substrate 100 in this disclosure. For example, in some embodiments, on the substrate 100, there may be a dielectric layer, which includes a silicon-based dielectric material with a low dielectric constant (i.e., a low k value), such as organic silicate glass (SiCOH), dense SiCOH, porous SiCOH, and other porous dielectric materials. In addition, there may be a hard mask layer on the substrate 100, and the hard mask layer may 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.

[0024] exist Figure 1BIn the example shown, the photoresist film 102 is formed on the substrate 100. In addition, the photoresist film 102 can be formed as part of a three-layer stack commonly used in photolithography patterning. The three-layer stack can be used to generate a pattern and transfer it to a hard mask, and then transferred to an underlying layer, such as a dielectric layer of the substrate 100. In various embodiments, the multilayer stack includes an underlying layer and a photoresist film 102 covering the underlying layer as an EUV photosensitive photoresist. In one or more embodiments, the underlying layer includes a carbon material (e.g., silicon carbide or silicon oxycarbide) and can be formed via a spin coating process or vapor deposition (e.g., CVD). The multilayer stack may further include an oxide layer (e.g., silicon oxide) or a nitride layer (e.g., titanium nitride or silicon nitride) on the underlying layer and the photoresist film 102. To simplify the description, Figure 1B Only the photoresist film 102 deposited directly on the substrate 100 is shown, but as described above, in various embodiments, any suitable multi-layer structure may be present as part of the substrate 100 .

[0025] In various embodiments, the photoresist film 102 comprises tin (Sn), antimony (Sb), hafnium (Hf), zirconium (Zr), zinc (Zn), etc., or a combination thereof. In certain embodiments, the photoresist film 102 comprises metal oxides, metal alkoxides, or methacrylates (MAAs) of Sn, Sb, Hf, Zr, Zn, etc., such as ZrMAA, SbMAA, SbMAA:F, HfMAA, ZnMAA, and ZnMAA:F. In certain embodiments, the photoresist film 102 can be a metal oxide network comprising metal alkoxides, metal alkene oxides, metal aryl oxides, or metal carboxylates. These groups bonded to the metal are generally represented by the chemical formulas -OR, -OR', -OAr, and -OOCR, respectively, wherein R is an alkyl, R' is an alkenyl, and Ar is an aryl. In some embodiments, the photoresist film 102 includes an organic metal bond, wherein an organic R group (e.g., a group with a carbon length between 1 and 10, a saturated and unsaturated bond, one or more aromatic groups, the like, 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 ordered structure such as a crystal. The number of the above functional groups bonded to the metal atom may vary for each metal atom, ranging from 1 to 4. The deposition of the photoresist film 102 may be performed by dry or wet processing. 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).

[0026] 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. 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 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 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 some embodiments, the exposure steps may be separated in time or space. Temporally separating the exposure steps may be achieved by changing the gas composition in the processing chamber. On the other hand, spatially separating the exposure steps may be achieved by using multiple spatially separated sections in the processing chamber and transferring the substrate from one section to another. To better separate the exposure steps in time, the vapor deposition may further include evacuating, purging, or both evacuating and purging the process chamber between the exposure steps. These additional steps may be useful to ensure that the reaction occurs only on the surface and not in the vapor phase. The ALD or pseudo-ALD method according to this embodiment may be particularly advantageous in achieving layer-by-layer growth of the photoresist film 102 with high uniformity.

[0027] In another embodiment, instead of using an ALD type of process, the precursors may be provided simultaneously in the process chamber to grow the photoresist film 102. The advantage of such an embodiment is that continuous growth of the photoresist film 102 may be achieved 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.

[0028] In other embodiments, the photoresist film 102 may be deposited by liquid deposition using alternating exposures of a tin-containing precursor liquid and an oxygen-containing precursor liquid. The liquid deposition may further include rinsing the substrate with a rinse solution to remove excess and / or unreacted portions of the precursor 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 isobutylcarbinol, n-hexane, tert-butyl alcohol, and isopropanol, or a mixture thereof. In another embodiment, the liquid precursors may be mixed first 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 precursor may be liquid, and thus two different delivery modes (gas and liquid) may be used for the deposition process.

[0029] In various embodiments, after the photoresist film 102 is formed on the substrate 100, a post-application bake may be optionally performed to remove any excess solvent from the wet process, residual volatile byproducts from the dry process, or both.

[0030] Figure 1C 1 shows a cross-sectional view of a substrate 100 after exposure to a light pattern (eg, EUV exposure). Figure 1C As shown, the method further includes exposing the substrate 100 to an EUV light pattern 104. The EUV light pattern 104 may be created using a photomask by placing the photomask between the substrate 100 and an EUV light source (not shown). In response to the exposure to the EUV light pattern 104, the exposed regions 105 of the photoresist film 102 may undergo a photoreaction, while the unexposed regions 107 remain unchanged. As a result of the photoreaction, the exposed regions 105 may include a cross-linked photoresist film, which may have material properties that are substantially different from the unreacted portions of the photoresist film 102 (i.e., the unexposed regions 107). Such differences in material properties include volatility, reactivity, and / or solubility, etc., thereby producing a tonality of the photoresist.

[0031] In various embodiments, during EUV exposure (see above Figure 1C ) and the development step (see below Figure 2A ), an optional post-exposure bake (PEB) may be performed before the substrate 100 is exposed to further differentiate the material properties between the exposed regions 105 and the unexposed regions 107. In some 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., such as 180° C. to 225° C. in an embodiment.

[0032] Figures 2A-2C The steps of an exemplary cyclic development process (also referred to as a pulse process or pulse mode) of the photoresist film 102 are shown, which can be performed after forming and exposing the photoresist film 102, as described above with respect to FIG. Figures 1A-1C The cyclic development process is a reaction process at the gas-solid interface, which can achieve better process control at the nanometer scale compared to wet processing, for example, for forming features with critical dimensions of a few nanometers or sub-nanometers. In some embodiments, the cyclic development process (also referred to as a cyclic reaction process) is a plasma-free process, such as a reactive sublimation process. In addition to developing the photoresist film 102, the cyclic reaction process can also be used as a descumming step to remove residues and defects on the photoresist film 102.

[0033] The cyclic development process includes a plurality of development steps, each of which is separated by a respective purge step. In each development step, a development gas flows into a processing chamber containing a substrate 100 to partially etch the unexposed area 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 flows into the processing chamber to purge the development gas. The purge gas may be a non-reactive gas (e.g., an inert gas) or a reactive gas that reacts with the unexposed area 107, which is different from the development gas. After the purge step, another development step is performed to further etch the unexposed area 107 of the photoresist film 102. The development step and the purge step may be repeated any suitable number of times. Subsequent development steps may be performed at the same development gas pressure, or at different pressures, such as a pressure that is gradually increased with each additional development step. Subsequent development steps may be performed at the same temperature of the processing chamber, or at different temperatures, so that the processing temperature at the beginning of the cyclic development process is different from the processing temperature at the end of the cyclic development process.

[0034] The cyclic development process is beneficial to improve the integrity of the development etching process, regardless of the depth-to-width ratio of the desired opening, and is also beneficial to improve the selectivity of the development etching. The cyclic development process can improve the integrity of the etching (in other words, remove more unexposed areas 107) while maintaining the selectivity of the etching (in other words, remove less exposed areas 105). This is beneficial to maintain the selectivity of the development etching at high temperatures (e.g., at about 60°C). In addition, a given dose of developing gas can develop more material in the unexposed areas 107 within a given feed time. In this way, the development etching can be completed without considering the depth-to-width ratio of the opening formed by the photoresist film 102.

[0035] Figure 2A catch Figure 1C , shows a cross-sectional view of a substrate 100 during a development step according to some embodiments. The substrate 100 is placed in a suitable processing chamber, and a developing gas 110 flows into the processing chamber. The developing gas 110 reacts with the unexposed area 107 of the photoresist film 102 to produce volatile byproducts, which then evaporate from the surface of the substrate 100. This causes the unexposed area 107 to be recessed relative to the exposed area 105, forming an opening 108 on the photoresist film 102. In some embodiments, the developing gas 110 is a reactive gas, such as hydrogen bromide (HBr), hydrogen chloride (HCl), boron trichloride (BCl3), an organic acid (such as a carboxylic acid), methanol, ethanol, isopropanol, etc., or a mixture or combination of the above. In some embodiments, different developing steps are performed using different developing gases 110. For example, the first developing step may use hydrogen bromide, and the second developing step may use boron trichloride.

[0036] The developing step may be performed using 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.

[0037] The developing step may be performed at a pressure in the process chamber ranging from 5 mTorr to 100 Torr. In some embodiments, each developing step is performed at the same pressure, such as a pressure of 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. For example, the pressure may be gradually increased from 10 mTorr to 2 Torr every 5 to 10 seconds, with the pressure doubling at each increment.

[0038] In other embodiments, the developing step is performed with the pressure gradually reduced, for example, the pressure is gradually reduced from 2 Torr to 10 mTorr every 5 to 10 seconds, with the pressure being halved each time.

[0039] In other embodiments, the developing steps are performed alternately at lower and higher pressures. For example, one 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.

[0040] The consecutive development steps may be performed at a lower pressure for the previous development step and a higher pressure for the next development step; the previous development step may be performed at a higher pressure and the next development step may be performed at a lower pressure; or the previous development step and the next development step may be performed at the same pressure. Any and all such arrangements of relative pressures between development steps fall within the scope of the disclosed embodiments.

[0041] Figure 2B 1 shows a cross-sectional view of a substrate 100 during a purge step according to some embodiments. The purge step is described above with respect to Figure 2A After the development step, the developing gas 110 is purged out of the processing chamber by flowing a purge gas 120. Each development step is followed by a purge step. Cyclic development processing with continuous development and purge steps can help improve the integrity of the development etching process regardless of the aspect ratio of the opening 108. Cyclic development processing with purge steps between development steps can also improve the selectivity of the development etching by removing more unexposed areas 107 while removing less exposed areas 105.

[0042] The purge step is accomplished by flowing a purge gas 120 into the processing chamber, and 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), etc., 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, isopropanol, n-butanol, tert-butanol, nonafluoro-tert-butyl alcohol, ethylene glycol, acetylacetone, hexafluoroacetylacetone, an organic acid (e.g., acetic acid, trifluoroacetic acid, or the like), the like, or a combination thereof. Using a reactive gas as the purge gas 120 can better control the etch selectivity under non-selective processing conditions, such as when the temperature is up to 250°C. For example, alternating the use of hydrogen bromide (HBr) as the developing gas 110 and a reactive purge gas 120 (e.g., boron trichloride (BCl3)) in the developing step can help improve selectivity and photolithography efficiency. The selectivity and roughness of the developing process can be adjusted by selecting appropriate chemicals (e.g., boron trichloride (BCl3) or water vapor (H2O)) for the purge gas. Subsequent purge steps can be performed at different pressures (e.g., at gradually increasing pressure, at gradually decreasing pressure, or at alternating increasing and decreasing pressures). Subsequent purge steps can be performed using different gas flow rates (e.g., the gas flow rate gradually increases, the gas flow rate gradually decreases, or the gas flow rate alternately increases and decreases). Subsequent purge steps can be performed at different purge durations.

[0043] In embodiments where the purge gas 120 is a non-reactive gas, the purge step may be performed using a non-reactive gas with a flow rate in the range of 100 sccm to 2000 sccm. The purge step may be performed at a temperature in the range of -30°C to 250°C in the process chamber. The purge step may be performed for a duration of 5 seconds to 60 seconds. The purge step may be performed at 1×10 -3 mTorr to 1×10 3 The pressure is in the millitorr range.

[0044] In embodiments where the purge gas 120 is a reactive gas, the purge step may be performed using a reactive gas with a flow rate in the range of 10 sccm to 500 sccm. The purge step may be performed at a temperature in the range of -30°C to 250°C in the process chamber. The purge step may be performed for a duration of 5 seconds to 120 seconds. The purge step may be performed at a temperature in the range of 1×10 -1 mTorr to 1×10 3 The pressure is in the millitorr range.

[0045] In some embodiments, the cyclic development process includes a non-reactive purge step using a non-reactive gas and a reactive purge step using a reactive gas. As an 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 purge steps and reactive purge steps fall within the scope of the disclosed embodiments.

[0046] In various embodiments, as described above Figure 2A The development step and the Figure 2B The purge step is repeated for a suitable number of cycles, wherein each cycle comprises a developing step followed by a purge step. For example, the developing step and the purge step may be repeated for 1 to 60 cycles. However, any suitable number of developing steps and purge steps may be used in any suitable order. For example, the first developing step may be preceded by the first purge step, and the last purge step may be followed by the last developing step.

[0047] Figure 2C FIG. 1 shows a cross-sectional view of a substrate 100 after one or more development steps and one or more purge steps of a cyclic development process according to some embodiments. Figure 1C-2B ) has been removed. Openings 108 extend through the remaining unexposed regions 107 of the photoresist film 102. Portions of the top surface of the substrate 100 are exposed through the openings 108. The unexposed regions 107 of the photoresist film 102 can then be used as a mask to etch the substrate 100, for example, to form conductive features in the substrate 100 (see below). Figures 3A-3C ). Embodiments of the cyclic development process can improve the integrity and selectivity of the development etch regardless of the aspect ratio of the opening 108, such that the substrate 100 is exposed through the opening 108 while retaining a sufficient amount of unexposed area 107 for subsequent etching of the substrate 100.

[0048] In the above Figures 1A-2CIn the described embodiment, the photoresist film 102 is a negative tone photoresist. In other embodiments, the photoresist film 102 may form a positive tone photoresist, wherein the exposed area 105 may be removed by a development step, and the unexposed area 107 remains. In one embodiment, the positive tone photoresist may be realized by performing an additional chemical treatment (such as polymerization) to improve the etching resistance of the unexposed area 107 after EUV exposure, while the photoreaction in the exposed area 105 may reduce the etching resistance.

[0049] Figures 3A-3D 1 shows a cross-sectional view of an intermediate step in an exemplary manufacturing process for forming conductive features in and on substrate 100. Figure 3A In the embodiment of the present invention, the opening 108 is extended into the substrate 100 to form an opening 118 using a suitable anisotropic etching technique, such as a reactive ion etch (RIE) process or an atomic layer etching (ALE) process using a fluorine chemistry. However, any suitable etching process may be used. The exposed area 105 of the photoresist film 102 remains on the substrate 100 and serves as a mask for the etching process. In some embodiments, the opening 118 exposes the top surface of the conductive feature 101 (such as a metal line) embedded in the substrate 100.

[0050] exist Figure 3B In the process, the exposed area 105 of the photoresist film 102 is removed from the substrate 100, the residue from the etching and planarization process is removed, and the conductive material 130 is formed on the substrate 100. The exposed area 105 of the photoresist film 102 can be removed by a suitable treatment, such as a planarization process (e.g., CMP), etc. In some embodiments, the residue from the etching and planarization process can be removed by a suitable cleaning process, such as washing with deionized water, hydrogen peroxide, SC-1, etc., or a combination thereof.

[0051] Still refer to Figure 3B , a conductive material 130 is formed on the substrate 100 to fill the opening 118 (see above Figure 3A 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. Next, the opening 118 is filled with the conductive material 130 (e.g., metal). For example, the conductive material 130 can be copper formed using electroplating. However, any suitable conductive material and deposition method can be used. In some embodiments, the conductive material 130 forms an electrical and physical contact with the top surface of the conductive feature 101.

[0052] Then, in Figure 3CIn the embodiment of the present invention, a planarization process (e.g., CMP) is used to remove excess conductive material from the top surface of the substrate 100, thereby forming a damascene conductive feature 132 in the substrate 100. In various embodiments, the conductive feature 132 is a high aspect ratio feature. The conductive feature 132 can be a conductive via that is physically and electrically coupled to the conductive feature 101 of the substrate 100.

[0053] exist Figure 3D In the embodiment of the present invention, an interconnect layer is formed on the substrate 100 and the conductive features 132. The interconnect layer includes an intermetal dielectric (IMD) 150 in which a conductive line 152 is formed. The IMD 150 includes an insulating material, such as SiO2 or a silicon oxide-based low-k dielectric (such as porous oxide, fluorosilicate glass (FSG) and orthosilicate glass (OSG)). In some embodiments, the IMD 150 includes a bottom layer, i.e., an etch stop layer (ESL), which includes a dielectric, such as Si3N4, SiO x N y , SiC or SiCN (not shown), etc. The IMD 150 may be formed using a suitable process such as CVD.

[0054] Still refer to Figure 3D , the conductive lines 152 can be formed by a conventional damascene process using, for example, a conductive material such as copper. As known to those skilled in the art, the damascene process includes patterning openings (e.g., trenches for the conductive lines 152) in the IMD 150, depositing a conformal barrier metal (e.g., TiN or TaN) liner, filling the openings with metal (e.g., using copper 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 damascened in the IMD 150. In some embodiments, each conductive line 152 is formed to form an electrical and physical coupling with one or more underlying conductive features 132 (e.g., conductive vias).

[0055] Figure 4 FIG. 2 is a process flow diagram of a method 200 for processing a substrate according to an embodiment. In step 202, a substrate 100 including a photoresist film 102 (e.g., a metal oxide resist) is received into a processing chamber, the photoresist film 102 having an exposed region 105 and an unexposed region 107, as described above with respect to FIG. Figure 2A described.

[0056] In step 204, the unexposed regions 107 of the photoresist film 102 are etched with the developing gas 110 in the processing chamber, leaving a residual portion of the unexposed regions 107, as described above with respect to Figure 2A In step 206, the developing gas 110 is purged out of the processing chamber using the purge gas 120, as described above with respect to Figure 2B In step 208, the remaining portion of the unexposed region 107 is further etched with the developing gas 110, as described above with respect to Figure 2A described.

[0057] 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 Figure 3B-3C described.

[0058] Figure 5 1 is a process flow diagram of a method 300 for patterning a 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 Figure 1C described.

[0059] Step 304 and step 306 are one cycle of a cyclic development process, which is performed on the photoresist film 102 in the processing chamber. In step 304, the developing gas 110 is flowed to etch the unexposed area 107 of the photoresist film 102, as described above with respect to Figure 2A In step 306, the developing gas 110 is purged out of the processing chamber by flowing the purge gas 120, as described above with respect to Figure 2B In various embodiments, step 304 and step 306 are repeated for an appropriate number of cycles, such as 1 cycle to 60 cycles.

[0060] Figure 6 FIG. 4 is a process flow diagram of a method 400 for processing a substrate according to some embodiments. In step 402, a photoresist film 102 (eg, a metal oxide resist) is formed on a substrate 100, as described above with respect to FIG. Figure 1B In step 404, the photoresist film 102 is exposed to the EUV light pattern 104 to form a pattern of the exposed area 105 and the unexposed area 107 of the photoresist film 102, as described above. Figure 1C described.

[0061] In step 406, the developing gas flows at a first pressure to etch the unexposed areas 107 of the photoresist film 102, as described above with respect to Figure 2AIn step 408, a first purge is performed to purge the developing gas 110 with the purge gas 120, as described above with respect to Figure 2B described.

[0062] In step 410, the developing gas flows 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 to purge the developing gas 110 with the purge gas 120, as described above. Figure 2B In some embodiments, steps 410 to 412 may then be repeated additional times in a cycle, for example until the unexposed regions 107 are removed. In some embodiments, the pressure of the developing gas is increased during each additional developing step.

[0063] Exemplary embodiments of the present disclosure are summarized herein. Other embodiments may also be understood from the entire content of this specification and the claims set forth herein.

[0064] 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 a developing gas; and etching the substrate using the exposed portion of the photoresist film as a mask.

[0065] Example 2. The method of Example 1, wherein the developing gas comprises hydrogen bromide, hydrogen chloride, acetic acid, trifluoroacetic acid, trifluoroethanol, perfluoro-tert-butyl alcohol, acetylacetone or hexafluoroacetylacetone.

[0066] Example 3. The method of Example 1, wherein the developing gas comprises boron trichloride.

[0067] Example 4. The method of any one of Examples 1 to 3, wherein the purge gas comprises argon, nitrogen, boron trichloride or water vapor.

[0068] Example 5. A method as described in any one of Examples 1 to 4, wherein the portion of the unexposed portion is etched with a first pressure to leave the 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.

[0069] Example 6. A method as described in any one of Examples 1 to 5, wherein etching a portion of 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, and the second temperature is greater than the first temperature.

[0070] Example 7. The method of any one of Examples 1 to 6, wherein the photoresist film is a metal oxide resist.

[0071] 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 treatment on the photoresist film in a processing chamber, wherein a first cycle of the cyclic development treatment 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.

[0072] Example 9. The method of example 8, wherein the developing gas comprises hydrogen bromide.

[0073] Example 10. The method of example 8 or 9, wherein the developing gas comprises boron trichloride.

[0074] Example 11. A method as described in any of Examples 8 to 10, wherein a second cycle of the cyclic development process includes flowing the developing gas in the processing chamber to further etch unexposed portions of the photoresist film, wherein flowing the developing gas in the second cycle is performed at a pressure greater than the pressure at which the developing gas is flowed in the first cycle.

[0075] Example 12. A method as described in any of Examples 8 to 10, wherein a second cycle of the cyclic development process includes flowing the developing gas in the processing chamber to further etch unexposed portions of the photoresist film, wherein flowing the developing gas in the second cycle is performed at the same pressure as the pressure at which the developing gas is flowed in the first cycle.

[0076] Example 13. The method of any one of Examples 8 to 12, wherein the purge gas is an inert gas.

[0077] Example 14. The method of any one of Examples 8 to 12, wherein the purge gas is boron trichloride or water vapor.

[0078] 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.

[0079] Example 16. The method of Example 15, wherein the first pressure is the same as the second pressure.

[0080] Example 17. The method of Example 15, wherein the second pressure is greater than the first pressure.

[0081] Example 18. The method of Example 17, further comprising flowing a developing gas at a third pressure to further etch the unexposed portion of the photoresist film, wherein the third pressure is greater than the second pressure.

[0082] 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.

[0083] 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.

[0084] Although this specification has been described in detail, it should be understood that various changes, substitutions and alternatives may be made without departing from the spirit and scope of the present disclosure defined by the appended claims. In different figures, the same elements are represented by the same reference numerals. In addition, the scope of the present disclosure is not intended to be limited to the specific embodiments described herein, as those of ordinary skill in the art will readily understand from the present disclosure, the processes, machines, manufactures, material compositions, devices, methods or steps currently existing or to be developed later may perform functions substantially the same as those in the corresponding embodiments described herein or achieve results substantially the same as those in the corresponding embodiments described herein. Therefore, the appended claims are intended to include such processes, machines, manufactures, material compositions, devices, methods or steps within their scope.

Claims

1. A method for processing a substrate, the method comprising: a receiving substrate comprising a 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; purge the developing gas out of the processing chamber with a purge gas; After the developing gas is purged, etching the remaining portion of the unexposed portion with the developing gas; as well as The substrate is etched using the exposed portion of the photoresist film as a mask.

2. The method of claim 1, wherein the developing gas comprises hydrogen bromide, hydrogen chloride, acetic acid, trifluoroacetic acid, trifluoroethanol, perfluoro-tert-butyl alcohol, acetylacetone or hexafluoroacetylacetone. 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. The method of claim 1, wherein etching a portion of 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, and the second pressure is greater than the first pressure.

6. The method of claim 1, wherein etching a portion of 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, and the second temperature is greater than the first temperature.

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

8. A method for patterning a photoresist film, the method comprising: exposing a photoresist film on a substrate to a pattern of extreme ultraviolet light; and The photoresist film is subjected to a cyclic development process 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 The developing gas is purged from the processing chamber by flowing the purge gas.

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

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

11. The method of claim 8, wherein a second cycle of the cyclic development process comprises flowing the developing gas in the processing chamber to further etch the unexposed portion of the photoresist film, wherein flowing the developing gas in the second cycle is performed at a pressure greater than a pressure at which the developing gas is flowed in the first cycle.

12. The method of claim 8, wherein a second cycle of the cyclic development process comprises flowing the developing gas in the processing chamber to further etch the unexposed portion of the photoresist film, wherein flowing the developing gas in the second cycle is performed at the same pressure as the pressure at which the developing gas was flowed 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. A method for 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 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 portion of the photoresist film; as well as The second purge of the developing gas is performed by flowing the purge gas. The method of claim 15 , wherein the first pressure is the same as the second pressure. The method of claim 15 , wherein the second pressure is greater than the first pressure.

18. The method of claim 17, further comprising flowing a developing gas at 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 of claim 15, wherein the developing gas comprises hydrogen bromide and the purge gas comprises boron trichloride.

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

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