In-situ deposition and densification of metal-containing resist layers

Abstract

This application relates to in-situ deposition and densification processes for metal-containing resist layers. Disclosed herein are metal-containing resist layers (e.g., metal oxide resist layers) that can improve lithographic resolution, methods for forming metal-containing resist layers, and lithographic methods using metal-containing resist layers. An example method includes forming a metal oxide resist layer over a workpiece by performing a deposition process to form metal oxide resist sub-layers of the metal oxide resist layer over the workpiece; and performing a densification process on at least one of the metal oxide resist sub-layers. Each deposition process forms a respective one of the metal oxide resist sub-layers. The densification process increases a density of the at least one of the metal oxide resist sub-layers. Parameters of the deposition process and / or parameters of the densification process can be adjusted to achieve different density profiles, different density characteristics, and / or different absorption characteristics to optimize patterning of the metal oxide resist layer.

Description

Technical Field

[0001] This disclosure relates to the semiconductor field, and more particularly to in-situ deposition and densification of metal-containing resist layers. Background Technology

[0002] Photolithography is widely used in integrated circuit (IC) manufacturing, where various IC patterns are transferred onto a workpiece to form IC devices. The photolithography process typically involves forming a resist layer on the workpiece, exposing the resist layer to patterned radiation, and developing the exposed resist layer to form a patterned resist layer. During subsequent IC processing (e.g., etching), the patterned resist layer is used as a masking element, where the resist pattern of the patterned resist layer is transferred onto the workpiece. The quality of the resist pattern directly affects the quality of the IC device. As IC technology continues to advance towards smaller technology nodes (e.g., down to 14 nanometers, 10 nanometers, and below), the line edge roughness (LER), line width roughness (LWR), and / or critical dimension uniformity (CDU) of the resist pattern become critical. The LER, LWR, and / or CDU of a resist pattern are influenced by a variety of factors, including the absorption characteristics of the resist layer (e.g., its ability to absorb radiation) and / or venting characteristics (e.g., its tendency to release contaminants). While existing resist layers and the techniques used to form them are generally sufficient to meet their intended purpose, they are not entirely satisfactory in all respects and require improvement. Summary of the Invention

[0003] According to a first aspect of this disclosure, a method for forming a semiconductor structure is provided, comprising: forming a metal oxide resist layer on a workpiece by: performing a deposition process to form metal oxide resist sublayers of the metal oxide resist layer on the workpiece, wherein each deposition process forms a corresponding one metal oxide resist sublayer among the metal oxide resist sublayers; and performing a densification process on at least one metal oxide resist sublayer among the metal oxide resist sublayers, wherein the densification process increases the density of the at least one metal oxide resist sublayer among the metal oxide resist sublayers.

[0004] According to a second aspect of this disclosure, a method for forming a semiconductor structure is provided, comprising: receiving a workpiece in a process chamber; performing at least two deposition processes in the process chamber to form a metal oxide resist layer on the workpiece; and performing a processing process in the process chamber to modify the density distribution of the metal oxide resist layer.

[0005] According to a third aspect of this disclosure, a metal oxide resist layer is provided, comprising: a first metal oxide resist sublayer having a first density; a second metal oxide resist sublayer disposed on the first metal oxide resist sublayer, wherein the second metal oxide resist sublayer has a second density; and a third metal oxide resist sublayer disposed on the second metal oxide resist sublayer, wherein the third metal oxide resist sublayer has a third density. Attached Figure Description

[0006] This disclosure can be best understood by reading in conjunction with the accompanying drawings through the following detailed description. It should be emphasized that, in accordance with standard industry practice, the various features are not drawn to scale and are for illustrative purposes only. In fact, for clarity of discussion, the dimensions of the various features may be arbitrarily enlarged or reduced.

[0007] Figure 1A The present invention illustrates a photolithography process for improving the fidelity of photolithographic patterns using a metal oxide resist layer according to various aspects of this disclosure.

[0008] Figure 1B The following are shown for forming according to various aspects of this disclosure. Figure 1A The cyclic metal resist deposition process for metal oxide resist layers.

[0009] Figure 1C The following are shown after deposition and after patterning, according to various aspects of the invention. Figure 1A A top view of the metal oxide resist layer.

[0010] Figure 2A Different lithography processes are shown that use metal oxide resist layers to improve the fidelity of lithographic patterns according to various aspects of this disclosure.

[0011] Figure 2B The following are shown for forming according to various aspects of this disclosure. Figure 2A The cyclic metal resist deposition process for metal oxide resist layers.

[0012] Figure 3A Different lithography processes are shown that use metal oxide resist layers to improve the fidelity of lithographic patterns according to various aspects of this disclosure.

[0013] Figure 3B The following are shown for forming according to various aspects of this disclosure. Figure 3A The cyclic metal resist deposition process for metal oxide resist layers.

[0014] Figure 4 A cyclic metal resist deposition process for forming a metal oxide resist layer is shown according to various aspects of this disclosure.

[0015] Figure 5 A cyclic metal resist deposition process for forming a metal oxide resist layer is shown according to various aspects of this disclosure. Detailed Implementation

[0016] This disclosure generally relates to methods for manufacturing integrated circuit (IC) devices, and more specifically to photolithography techniques and / or photolithography materials implemented during the manufacturing of IC devices.

[0017] The following disclosure provides numerous different embodiments or examples for implementing various features of the provided subject matter. Specific examples of components and arrangements are described below to simplify this disclosure. Of course, these are merely examples and are not intended to be limiting. For example, forming a first feature on or over a second feature in the following description can include embodiments in which the first and second features are formed in direct contact, and can also include embodiments in which an additional feature can be formed between the first and second features such that the first and second features do not need to be in direct contact. Furthermore, spatially related terms such as “lower,” “higher,” “horizontal,” “vertical,” “above,” “above,” “below,” “under,” “up,” “top,” “bottom,” etc., and their derivatives (e.g., “horizontally,” “downward,” “upward,” etc.) are used to readily describe the relationship of one feature of this disclosure relative to another feature. Spatially related terms are intended to cover different orientations of the device including the feature. Furthermore, when numbers or ranges of numbers are described using terms such as “substantially,” “about,” or “approximately,” the term is intended to cover numbers within a reasonable range that takes into account variations inherent to occur during manufacturing, as understood by those skilled in the art. For example, based on known manufacturing tolerances associated with the characteristics of manufacturing that are associated with numbers, a number or range of numbers encompasses a reasonable range including said number, such as within + / - 10% of said number. For example, a material layer having a thickness of “about 5 nm” can include a size range of 4.5 nm to 5.5 nm, where manufacturing tolerances associated with the deposited material layer are known to those skilled in the art to be + / - 10%. Furthermore, reference numerals and / or letters may be repeated in various examples within this disclosure. Such repetition is for simplicity and clarity and does not in itself indicate a relationship between the various embodiments and / or configurations discussed.

[0018] Photolithography is widely used in IC manufacturing, where various IC patterns are transferred onto a workpiece to form IC devices. The photolithography process involves forming a resist layer on the workpiece and exposing the resist layer to patterned radiation. After exposing the resist layer to patterned radiation, the resist layer is developed in a developer (in other words, a chemical solution). The developer removes portions of the resist layer (e.g., the exposed portions of a positive resist layer or the unexposed portions of a negative resist layer), thus forming a patterned resist layer. This patterned resist layer is then typically used as a masking element during subsequent processes (e.g., etching or implantation processes) to transfer the pattern in the patterned resist layer (referred to herein as the resist pattern) onto the workpiece. Advanced photolithography materials (e.g., chemically amplified resist (CAR) materials) have been introduced to improve the sensitivity (S) of the resist layer to radiation, thereby maximizing radiation utilization. Sensitivity generally corresponds to the amount of incident radiation (the amount of energy per unit area) required to generate a chemical reaction sufficient to define a pattern in the resist layer. For example, CAR materials can undergo various chemical reactions after exposure to radiation, chemically amplifying their response to radiation, which reduces sensitivity and thus reduces the exposure dose required to define the resist pattern. CAR materials typically include a polymer resistant to IC processes (e.g., etching), an acid-generating component (e.g., a photoacid generator (PAG)), and a solvent component. The PAG generates an acid upon exposure to radiation, which acts as a catalyst for a chemical reaction that reduces (or increases) the solubility of the exposed portion of the resist layer. For example, the acid generated by the PAG catalyzes the crosslinking of the polymer, thereby reducing the solubility of the exposed portion.

[0019] While CAR materials are configured to reduce sensitivity, they must also meet other resist performance characteristics, such as resolution (R), resist contrast, and roughness. Resolution generally describes the resist material's ability to print (imprint) the minimum feature size with acceptable quality and / or control. Resist contrast, resist thickness loss, proximity effect, resist material expansion and / or contraction (typically caused by development), and / or other resist properties and / or lithographic properties all contribute to resolution. Resist contrast generally refers to the resist material's ability to distinguish between bright (exposed) and dark (unexposed) areas. Resist materials with higher contrast provide better resolution, resist profile, and / or roughness. Roughness, such as line edge roughness (LER) and / or line width roughness (LWR), typically describes whether the pattern in the resist layer includes edge variations, width variations, critical size variations, and / or other variations. For example, LER generally describes the deviation of a line's edge, while LWR generally describes the deviation of a line's width, such as the deviation from the line's critical size (CD) width. Improving one resist property (e.g., reducing LER) often comes at the cost of degrading another resist property (e.g., increasing sensitivity). The attempt to simultaneously minimize resolution, LER, and sensitivity is often referred to as the RLS tradeoff. Overcoming the RLS tradeoff presents a challenge to meeting the lithography process requirements of advanced IC technology nodes, which feature ever-shrinking feature sizes, thus necessitating increasingly smaller resist pattern sizes and finer lithography resolution.

[0020] Extreme ultraviolet (EUV) lithography, utilizing radiation in the EUV wavelength range, holds promise for meeting finer lithographic resolution constraints, particularly in IC manufacturing below 10 nm. However, EUV wavelengths typically require highly sensitive CAR materials because the exposure dose required to meet resolution, contrast, and / or LER requirements, as well as yield requirements (e.g., wafer per hour (WPH)), is limited by conventional EUV sources. For example, since the number of photons absorbed by a given amount of resist material is proportional to wavelength, and the amount of absorbed energy is proportional to the exposure dose, as the wavelength decreases, the total absorbed energy is discretized into fewer photons. Therefore, when exposed to the same exposure dose, a given amount of resist material absorbs fewer EUV photons than DUV photons, which often means that the CAR material produces less acid in catalytic reactions. This phenomenon is commonly referred to as shot noise. While increasing the EUV exposure dose can mitigate shot noise, thereby improving resolution, contrast, and / or roughness, this can be achieved by increasing EUV source power or reducing scan speed (in other words, reducing yield (e.g., WPH)). Since current EUV sources have limited ability to meet the high-power EUV source requirements for CAR materials, and reducing yield is not a viable option to meet the requirements of next-generation IC manufacturing, the following metal oxide resist materials are being explored as potential alternatives for CAR materials in EUV lithography: these metal oxide resist materials exhibit sufficient sensitivity to radiation while still satisfying other RLS properties (such as resolution and LER).

[0021] Metal oxide resist (MOS) materials have been observed to exhibit better EUV absorption properties (e.g., MOS materials can absorb more EUV photons than CAR materials), better LER / LWR properties (e.g., MOS materials are often less susceptible to secondary electron exposure and / or acid amplification effects that cause resist blurring in CAR materials), and better etching properties than CAR materials (e.g., MOS materials achieve greater etch selectivity when used as etching masks compared to CAR materials). This disclosure explores deposition techniques for further improving the patterning properties of MOS materials. For example, this disclosure recognizes that MOS materials formed by conventional deposition techniques have random, loose, and often disordered, non-dense, and / or non-uniform atomic structures, which may reduce LER / LWR and patterning uniformity. Furthermore, such atomic structures may lead to undesirable venting that can contaminate workpieces treated with MOS materials and / or process tools used to process (e.g., deposition, exposure, development, etc.) MOS materials. Therefore, this disclosure proposes a method for forming a metal oxide resist material having an atomic structure that is less random, looser, and more ordered, denser, and / or more uniform compared to metal oxide resist materials formed using conventional deposition techniques. The disclosed method includes performing a cyclic deposition process to form metal oxide resist sublayers, which are combined to form a metal oxide resist layer, and performing a densification process that increases the density of at least one metal oxide resist sublayer. The deposition process and densification process can be performed in the same process chamber (i.e., in situ). Parameters of the deposition process and / or densification process are adjusted to obtain uniform or different densities in the metal oxide resist sublayers, thereby providing different density distributions. In some embodiments, the densification process is performed prior to the deposition process, for example, to enhance the adhesion of the metal oxide resist layer to the workpiece. The metal oxide resist layer formed as described in this disclosure can reduce venting, improve LER / LWR, and / or improve pattern uniformity on the wafer. The different embodiments disclosed herein offer different advantages, and not all embodiments necessarily have specific advantages.

[0022] Go to Figures 1A to 1C , Figure 1A Photolithography processes, such as photolithography process A and photolithography process B, are illustrated using metal oxide resist layers to improve the fidelity of photolithographic patterns according to various aspects of this disclosure. Figure 1B A cyclic metal resist deposition process A for forming a metal oxide resist layer in photolithography process B, according to various aspects of this disclosure, is shown; and Figure 1CA top view of a workpiece after deposition and after patterning of the metal oxide resist layer used in lithography processes A and B, according to various aspects of this disclosure, is shown. Figures 1A to 1C The image depicts a portion or the entirety of a workpiece 10 at an intermediate stage of IC device manufacturing, wherein workpiece 10 undergoes photolithography process A or photolithography process B. In some embodiments, the IC device is a microprocessor, memory, and / or other IC devices, or a portion thereof. Workpiece 10 may be a portion of an IC chip, a system-on-a-chip (SoC), or a portion thereof, which includes various passive and active microelectronic devices, such as resistors, capacitors, inductors, diodes, p-type field-effect transistors, n-type field-effect transistors, metal-oxide-semiconductor field-effect transistors, complementary metal-oxide-semiconductor transistors, bipolar junction transistors, laterally diffused metal-oxide-semiconductor transistors, high-voltage transistors, high-frequency transistors, fin field-effect transistors, gate-all-around transistors, other suitable IC components, or combinations thereof. For clarity, simplified representations have been provided. Figures 1A to 1C To better understand the inventive concept of this disclosure, additional features may be added to the workpiece 10, photolithography process A, photolithography process B, and / or cyclic metal resist deposition process A, and some features described below may be replaced, modified, or eliminated in other embodiments of the workpiece 10, photolithography process A, photolithography process B, and / or cyclic metal resist deposition process A.

[0023] refer to Figures 1A to 1CWorkpiece 10 includes a wafer 15 and a material layer 20 (also referred to herein as the lower layer) disposed on the wafer 15. Wafer 15 includes a substrate (e.g., a semiconductor substrate), a mask (also referred to as a photomask or photomask template), or any base material on which processing can be performed to provide a material layer for forming various features of an IC device. Depending on the IC manufacturing stage, wafer 15 includes various material layers (e.g., dielectric layers, semiconductor layers, and / or metal layers) configured to form IC features (e.g., n-wells, p-wells, isolation structures (e.g., shallow trench isolation structures and / or deep trench isolation structures), source / drain features (including epitaxial source / drain features), metal gates and / or dummy gates, gate spacers, source / drain contacts, gate contacts, vias, metal lines, other IC features, or combinations thereof). In some embodiments, material layer 20 is a semiconductor layer, including, for example, silicon, germanium, silicon-germanium, other suitable semiconductor components, or combinations thereof. In some embodiments, material layer 20 is a metal layer, including, for example, titanium, aluminum, tungsten, tantalum, copper, cobalt, ruthenium, alloys thereof, other suitable metal components and / or alloys thereof, or combinations thereof. In some embodiments, material layer 20 is a dielectric layer, including, for example, silicon, metal, oxygen, nitrogen, carbon, other suitable dielectric components, or combinations thereof. In some embodiments, material layer 20 is a hard mask layer to be patterned for use in subsequent processing of workpiece 10. In some embodiments, material layer 20 is an anti-reflective coating (ARC) layer. In some embodiments, material layer 20 is a layer for forming gate features, source / drain features, and / or interconnect features, the gate features being, for example, a gate dielectric and / or a gate electrode, the source / drain features being, for example, an epitaxial source / drain, and the interconnect features being, for example, a multilayer interconnected conductive structure or dielectric layer of workpiece 10. In some embodiments, where workpiece 10 is fabricated as a mask for patterning IC devices, wafer 15 is a mask substrate comprising a transparent material and / or a low thermal expansion material (e.g., glass, quartz, titanium silicon oxide, and / or other suitable materials), and material layer 20 is the layer to be processed to form IC patterns in wafer 15, such as an absorber layer (e.g., material layer 20 comprising chromium). This disclosure contemplates embodiments in which material layer 20 is omitted in workpiece 10 and wafer 15 is processed directly, as well as embodiments in which material layer 20 comprises more than one material layer.

[0024] Both photolithography process A and photolithography process B begin by depositing a metal oxide resist layer having a target thickness T on material layer 20, for example, metal oxide resist layer 30 in photolithography process A and metal oxide resist layer 40 in photolithography process B. Both metal oxide resist layer 30 and metal oxide resist layer 40 are sensitive to radiation used in the photolithography exposure process, such as deep ultraviolet (DUV) radiation, EUV radiation, electron beam radiation, ion beam radiation, and / or other suitable radiation. In some embodiments, metal oxide resist layer 30 and metal oxide resist layer 40 are sensitive to radiation with wavelengths less than about 13.5 nm. Each of metal oxide resist layer 30 and metal oxide resist layer 40 comprises a radiation-sensitive material containing a metal and oxygen, wherein the metal is hafnium, titanium, zirconium, tantalum, tin, lanthanum, indium, antimony, other metallic components that promote absorption of radiation (e.g., EUV radiation) and / or resistance to IC processes (e.g., etching) used during the manufacture of workpiece 10, or a combination of the foregoing. In some embodiments, the metal oxide resist layer 30 and / or the metal oxide resist layer 40 may include other resist components that promote radiation absorption and / or cross-linking reactions after exposure to radiation. These components are, for example, photoacid-generating agents (PAG), thermal acid-generating agents (TAG), photodegradable bases (PDB), other suitable resist components, or combinations thereof. In some embodiments, an ARC layer is formed on the material layer 20 prior to depositing the metal oxide resist layer 30 and / or the metal oxide resist layer 40, such that the metal oxide resist layer 30 and / or the metal oxide resist layer 40 is deposited on the ARC layer. The ARC layer may be a nitrogen-free ARC (NFARC) layer, which includes silicon oxide, silicon carbide, other suitable materials, or combinations thereof. In some embodiments, more than one layer (including one or more ARC layers) may be formed between the material layer 20 and the metal oxide resist layer 30 and / or the metal oxide resist layer 40. The metal oxide resist layer 30 and / or the metal oxide resist layer 40 are also referred to as metal resist layer, photosensitive metal layer, metal imaging layer, metal patterning layer, and / or radiation-sensitive metal layer.

[0025] The metal oxide resist layer 30 and the metal oxide resist layer 40 are formed by different deposition processes, resulting in different properties affecting pattern fidelity. In photolithography process A, the metal oxide resist layer 30 is uniformly deposited on the material layer 20 by a chemical vapor deposition (CVD) process. In some embodiments, the CVD process includes: loading a workpiece 10 having the material layer 20 disposed on a wafer 15 into a process chamber; heating the workpiece 10 to a desired temperature (e.g., a temperature required to promote the chemical reaction required to form a metal and oxygen-containing resist material on the material layer 20); allowing one or more precursors and / or carriers to flow into the process chamber, where the precursors react and / or decompose to form a metal and oxygen-containing resist material on the material layer 20; and removing any remaining precursors (e.g., unreacted precursors), carriers, and / or byproducts from the process chamber. Metal and oxygen-containing resist material accumulates on material layer 20, and the CVD process is stopped only when the metal and oxygen-containing resist material accumulated on material layer 20 reaches a target thickness T. During the CVD process, precursors may react with each other, react with material layer 20, react with the metal and oxygen-containing resist material accumulated on material layer 20, and / or react with byproducts of the aforementioned chemical reactions to form metal oxide resist layer 30. In some embodiments, the CVD process is plasma-enhanced CVD (PECVD), remote PECVD (RPECVD), metal-organic CVD (MOCVD), low-pressure CVD (LPCVD), ultra-high vacuum CVD (UHVCVD), subatmospheric pressure CVD (SACVD), laser-assisted CVD (LACVD), aerosol-assisted CVD (AACVD), atomic layer CVD (ALCVD), other suitable CVD processes, or combinations thereof. In some embodiments, a metal oxide resist layer 30 of thickness T is uniformly deposited on the material layer 20 by atomic layer deposition (ALD), physical vapor deposition (PVD), or other suitable deposition processes.

[0026] Because the chemical reactions during CVD processes are random and / or incomplete, the metal oxide resist layer 30 has been observed to exhibit a random, loose, and often disordered, non-dense, and / or non-uniform atomic structure, which may reduce patterning uniformity. For example, the atomic structure of the metal oxide resist layer 30 may include randomly stacked, loosely packed metal atoms, oxygen atoms, and individual metal oxide molecules (Me1O2). x (where x is the number of oxygen atoms) and / or metal oxide clusters (Me y O zWhere y is the number of metal atoms and z is the number of oxygen atoms, these can be collectively referred to as the metal-oxygen composition MeO. The metal-oxygen composition MeO may not have an ordered arrangement (e.g., a repeating pattern of metal-oxygen composition MeO), which may result in the metal oxide resist layer 30 having clusters of very different metal-oxygen composition MeO, and therefore having a non-uniform density (e.g., the amount of metal-oxygen composition MeO in one part of the metal oxide resist layer 30 is different from the amount of metal-oxygen composition MeO in another part of the metal oxide resist layer 30 of similar size). Since the amount of radiation a material can absorb depends on its density, and the metal oxide resist layer 30 has a non-uniform density, the metal oxide layer 30 may absorb radiation non-uniformly. This reduces the LER / LWR achievable by patterning the metal oxide layer 30 (e.g., the patterned metal oxide layer 30 exhibits a larger LER / LWR than desired, along with degraded linewidth and / or line edge uniformity), and / or requires a larger exposure dose to ensure adequate and / or uniform radiation absorption to improve the LER / LWR. Furthermore, the random arrangement of the metal-oxygen component MeO can lead to the formation of vacancies and / or dislocations (V) within the atomic structure of the metal oxide resist layer 30, and incomplete chemical reactions during the CVD process may produce metal-oxygen component MeO that is not connected (bonded) to any other metal-oxygen component MeO in the metal oxide resist layer 30, such as... Figure 1A As shown. These “loose” metal-oxygen components MeO and / or weakly bonded metal-oxygen components MeO may vent during subsequent processing (i.e., escape from the metal oxide resist layer 30 into the environment of the process chamber), which may contaminate the workpiece 10 and / or the process chamber. The vented metal and oxygen components MeO may cause film defects, for example, by scraping and / or stripping the metal oxide resist layer 30, the material layer 20, and / or the wafer 15. Furthermore, since multiple wafers are processed in the process chamber to form metal oxide resist layers (e.g., metal oxide resist layer 30), pattern fidelity deteriorates over time as vented contaminants accumulate in the process chamber.

[0027] To address these issues, this disclosure proposes a cyclic metal oxide resist deposition process that provides a metal oxide resist layer that is denser and absorbs radiation better than metal oxide resist layer 30. This allows for patterning of the metal oxide resist layer with a lower exposure dose while still achieving uniform absorption of radiation to improve LER / LWR. The denser metal oxide resist layer also exhibits less venting compared to metal oxide resist layer 30. In some embodiments, the atomic structure of the metal oxide resist layer formed by the proposed cyclic metal oxide resist deposition process comprises metal-oxygen components stacked in an ordered arrangement (e.g., a repeating pattern of metal-oxygen components). In some embodiments, the atomic structure of the metal oxide resist layer formed by the proposed cyclic metal oxide resist deposition process has fewer vacancies and / or fewer incomplete metal-oxygen bonds (and in some embodiments, substantially no vacancies and / or incomplete metal-oxygen bonds) compared to metal oxide resist layer 30. In some embodiments, clusters of metal-oxygen components are non-uniformly distributed in the metal oxide resist layer formed by the proposed cyclic metal oxide resist deposition process, such that the metal oxide resist layer formed by the proposed cyclic metal oxide resist deposition process has a substantially uniform density (e.g., the amount of metal-oxygen components is substantially the same in different but similarly sized portions of the metal oxide resist layer). In some embodiments, the concentration of metal oxide clusters, metal concentration, oxygen concentration, and / or metal oxide concentration in the proposed metal oxide resist layer increases or decreases from the top surface to the bottom surface of the metal oxide resist layer to achieve gradient density characteristics (e.g., density increases or decreases from the top surface to the bottom surface of the metal oxide resist layer). In some embodiments, the concentration of metal oxide clusters, metal concentration, oxygen concentration, and / or metal oxide concentration in the proposed metal oxide resist layer is different at different depths to achieve desired density characteristics (e.g., those characteristics described herein). In some embodiments, the proposed metal oxide resist layer may include 12-MeO according to the desired density characteristics (e.g., those characteristics described herein). x Cluster, 8-MeO x Cluster, 6-MeO x Cluster, 4-MeO x Clusters, dimers - MeO x Clusters, and / or single-MeO x cluster.

[0028] Moving to photolithography process B, cyclic metal resist deposition process A forms a metal oxide resist layer 40 with a substantially uniform density from bottom to top, for example, from the bottom surface of the metal oxide layer 40 (e.g., bonded to material layer 20) to the top surface of the metal oxide resist layer 40. The density of the metal oxide resist layer 40 is greater than that of the metal oxide resist layer 30, such that the metal oxide resist layer 40 absorbs more radiation than the metal oxide resist layer 30 when exposed to the same exposure dose, and absorbs this radiation more uniformly than the metal oxide resist layer 30. For example, cyclic metal resist deposition process A forms metal oxide resist sublayers 40A, 40B, 40C, and 40D, which are combined to form a metal oxide resist layer 40 with a thickness T. Metal oxide resist sublayers 40A-40D each have thicknesses t1, t2, t3, and t4, respectively, wherein the sum of thicknesses t1, t2, t3, and t4 equals the target thickness T. The densities of metal oxide resist sublayers 40A, 40B, 40C, and 40D are substantially the same. In the illustrated embodiment, the densities of metal oxide resist sublayers 40A-40D are all greater than the density of metal oxide resist layer 30. In the illustrated embodiment, thicknesses t1, t2, t3, and t4 are substantially the same. In some embodiments, thicknesses t1, t2, t3, and / or t4 may be different or the same depending on the desired density distribution and / or density characteristics.

[0029] Go to Figure 1BThe cyclic metal resist deposition process A comprises four cycles, each cycle forming one of the metal oxide resist sublayers 40A-40D, and each cycle includes a deposition process and a densification process. For example, the cyclic metal resist deposition process A includes cycles 1, 2, 3, and 4 (alternatively referred to as stages 1-4). Cycle 1 includes: performing a deposition process 50-1 to form a metal oxide resist sublayer 40A' having a thickness t1 and a first density on the material layer 20; and performing a densification process 52-1 on the metal oxide resist sublayer 40A' to form a metal oxide resist sublayer 40A having a second density greater than the first density. Cycle 2 includes: performing a deposition process 50-2 to form a metal oxide resist sublayer 40B' having a thickness t2 and a third density on the metal oxide resist sublayer 40A; and performing a densification process 52-2 on the metal oxide resist sublayer 40B' to form a metal oxide resist sublayer 40B having a fourth density greater than the third density. Cycle 3 includes: performing a deposition process 50-3 to form a metal oxide resist sublayer 40C' having a thickness t3 and a fifth density on the metal oxide resist sublayer 40B; and performing a densification process 52-3 on the metal oxide resist sublayer 40C' to form a metal oxide resist sublayer 40C having a sixth density greater than the fifth density. Cycle 4 includes: performing a deposition process 50-4 to form a metal oxide resist sublayer 40D' having a thickness t4 and a seventh density on the metal oxide resist sublayer 40C; and performing a densification process 52-4 on the metal oxide resist sublayer 40D' to form a metal oxide resist sublayer 40D having an eighth density greater than the seventh density. In the depicted embodiments, the second, fourth, sixth, and eighth densities (i.e., the densities after densification processes 52-1 to 52-4) are substantially the same, such that the metal oxide resist layer 40 has a substantially uniform density from bottom to top. In some embodiments, the first, third, fifth, and seventh densities (i.e., the densities of the deposited metal and oxygen-containing resist material) are substantially the same. In some embodiments, the first, third, fifth, and / or seventh densities are the same as the density of the metal oxide resist layer 30. In some embodiments, the first, third, fifth, and / or seventh densities are different. In some embodiments, densification processes 52-1 to 52-4 may reduce the thicknesses t1, t2, t3, and / or t4, respectively, such that the thicknesses t1 to t4 of the deposited metal oxide resist sublayers 40A'-40D' are greater than the thicknesses t1 to t4 of the metal oxide resist sublayers 40A-40D.

[0030] In some embodiments, deposition processes 50-1 to 50-4 are CVD processes. In some embodiments, deposition processes 50-1 to 50-4 are ALD processes. After a workpiece 10 having a material layer 20 disposed on a wafer 15 is loaded into a process chamber, each deposition process 50-1 to 50-4 may include: heating the workpiece 10 to a desired temperature (e.g., a temperature required to promote the chemical reaction necessary for the formation of a metal and oxygen-containing resist material on the material layer 20); allowing one or more deposition precursors and / or supports to flow into the process chamber, wherein the deposition precursors react and / or decompose in the process chamber to form a metal and oxygen-containing resist material on the material layer 20; and removing any remaining deposition precursors (e.g., unreacted deposition precursors), supports, and / or byproducts from the process chamber. Each deposition process 50-1 to 50-4 has at least one deposition stage and at least one removal stage. During the deposition phase, metal- and oxygen-containing resist materials accumulate on material layer 20, and the deposition phase is stopped only when the metal- and oxygen-containing resist materials accumulated on material layer 20 have a thickness t1, t2, t3, or t4 (depending on the number of cycles). During the deposition phase, deposition precursors may react with each other, react with material layer 20, react with the metal- and oxygen-containing resist materials accumulated on material layer 20, and / or react with byproducts of the aforementioned chemical reactions to form metal oxide resist sublayers 40A-40D. In some embodiments, the deposition precursors include metal-containing precursors, reactive gases, and / or carriers. In some embodiments, the metal-containing precursors include M a R b X cWherein, 1 ≤ a ≤ 2, b ≥ 1, and c ≥ 1. In some embodiments, b + c ≤ 5. In some embodiments, M is Sn, Bi, Sb, In, Te, Ti, Zr, Hf, V, Co, Mo, W, Al, Ga, Si, Ge, P, As, Y, La, Ce, or Lu. In some embodiments, R is a substituted alkyl group, a substituted alkenyl group, a substituted carboxylate group, an unsubstituted alkyl group, an unsubstituted alkenyl group, or an unsubstituted carboxylate group. In some embodiments, X is a halogen group or a sulfonate group. In some embodiments, the reaction gas includes amine, water, ozone, hydrogen peroxide, other suitable reaction gas components, or combinations thereof. In some embodiments, the carrier gas includes argon (e.g., Ar), helium (e.g., He), nitrogen (e.g., N2), other suitable carrier gas components, or combinations thereof. In some embodiments, the flow rate of the deposition precursor is from about 10 sccm to about 1000 sccm. In some embodiments, the flow rate of the support is from about 100 sccm to about 10000 sccm. In some embodiments, power is applied to the deposition precursor to generate plasma, for example, a power of about 10 W to about 1000 W. In some embodiments, the plasma is generated by a radio frequency (RF) power source, such that the power is RF power. In some embodiments, the duration of the deposition phase is about 3 seconds to about 3600 seconds. In some embodiments, the pressure maintained in the process chamber during the deposition phase is about 0.1 Torr to about 150 Torr. In some embodiments, the temperature maintained in the process chamber during the deposition phase is about 25°C to about 300°C. In some embodiments, the purging phase may include the influx of an inert gas (e.g., argon-containing gas, helium-containing gas, other suitable inert gases, or combinations thereof) into the process chamber. In some embodiments, the inert gas flow rate is about 100 sccm to about 10000 sccm. In some embodiments, the duration of the purging phase is about 3 seconds to about 1000 seconds. In some embodiments, the pressure maintained in the process chamber during the purging phase is about 10 Torr to about 760 Torr. In some embodiments, the temperature maintained in the process chamber during the purging phase is about 25°C to about 300°C. In some embodiments, deposition processes 50-1 to 50-4 are the same. In some embodiments, deposition processes 50-1 to 50-4 are different. In some embodiments, deposition processes 50-1 to 50-4 are any combination of deposition processes for achieving the desired density distribution and / or density characteristics of the metal oxide resist layer 40.

[0031] Densification processes 52-1 to 52-4 include a treatment stage and a cleaning stage. The treatment stage subjects the workpiece 10 to a process that densifies (i.e., increases the density) the metal- and oxygen-containing resist material. In some embodiments, the treatment modifies the atomic structure of the metal- and oxygen-containing resist material, making the atomic structure more ordered and / or more compactly packed after the treatment. For example, the treatment rearranges the metal and / or oxygen atoms of the metal- and oxygen-containing resist material, resulting in an ordered arrangement of metal and / or oxygen atoms after the treatment, and / or a smaller spacing between metal and / or oxygen atoms after the treatment. In some embodiments, the treatment enhances metal-oxygen bonding and / or improves the uniformity of metal-oxygen bonding in the metal- and oxygen-containing resist material. For example, the treatment induces a chemical reaction such that partially reacted components of the metal- and oxygen-containing resist material are fully reacted after the treatment, and / or unreacted components of the metal- and oxygen-containing resist material in the process chamber are partially or fully reacted after the treatment. In some embodiments, the treatment induces partial crosslinking in the metal and oxygen-containing resist material, which can increase the density of the metal and oxygen-containing resist material. The scavenging phase removes (removes) any remaining precursors (e.g., unreacted deposition precursors, unreacted treatment precursors, “loose” reactive precursors, “loose” metal and oxygen components, and / or other “loose” reactive components), carriers, and / or byproducts from the process chamber, which can further reduce venting from the metal oxide resist layer 40 and the resulting contamination of the workpiece 10 and / or the process chamber compared to the metal oxide resist layer 30. In some embodiments, the scavenging phase includes influencing the process chamber with an inert gas (e.g., argon-containing gas, helium-containing gas, other suitable inert gases, or combinations thereof). In some embodiments, the inert gas flow rate is from about 100 sccm to about 10,000 sccm. In some embodiments, the duration of the scavenging phase is from about 3 seconds to about 600 seconds. In some embodiments, the pressure maintained in the process chamber during the purging phase is from about 10 Torr to about 760 Torr. In some embodiments, the temperature maintained in the process chamber during the purging phase is from about 25°C to about 300°C.

[0032] Example processes described herein that can increase the density of metal- and oxygen-containing resist materials and / or achieve modifications to metal- and oxygen-containing resist materials include: plasma densification processes, soft baking processes, UV radiation processes, infrared (IR) radiation processes, other suitable densification processes, or combinations thereof. In some embodiments, densification processes 52-1 to 52-4 are of the same type (e.g., densification processes 52-1 to 52-4 are all plasma densification processes). In some embodiments, densification processes 52-1 to 52-4 are of different types (e.g., densification processes 52-1 and 52-4 are plasma densification processes, while densification processes 52-1 and 52-3 are soft baking processes). In some embodiments, densification processes 52-1 to 52-4 are any combination of densification processes for achieving a desired density distribution and / or density characteristics of the metal oxide resist layer 40.

[0033] In some embodiments, the plasma densification process includes: flowing one or more densification precursors and / or supports into a process chamber; generating plasma from the densification precursors; and exposing a metal oxide resist sublayer to the plasma (e.g., bombarding the metal oxide resist sublayer with plasma). In some embodiments, the densification precursor includes a metal-containing precursor, a reactive gas, and / or a support. In some embodiments, the metal-containing precursor includes M... a R b X cWherein, 1 ≤ a ≤ 2, b ≥ 1, and c ≥ 1. In some embodiments, b + c ≤ 5. In some embodiments, M is Sn, Bi, Sb, In, Te, Ti, Zr, Hf, V, Co, Mo, W, Al, Ga, Si, Ge, P, As, Y, La, Ce, or Lu. In some embodiments, R is a substituted alkyl group, a substituted alkenyl group, a substituted carboxylate group, an unsubstituted alkyl group, an unsubstituted alkenyl group, or an unsubstituted carboxylate group. In some embodiments, X is a halogen group or a sulfonate group. In some embodiments, the reaction gas includes amine, water, ozone, hydrogen peroxide, other suitable reaction gases, or combinations thereof. In some embodiments, the carrier gas includes argon (e.g., Ar), helium (e.g., He), nitrogen (e.g., N2), other suitable carrier gas components, or combinations thereof. In some embodiments, the flow rate of the densification precursor is from about 10 sccm to about 1000 sccm. In some embodiments, the flow rate of the support is from about 100 sccm to about 10000 sccm. In some embodiments, the power applied to the densification precursor and / or support to generate plasma is from about 10 W to about 1000 W. In some embodiments, the power applied to the densification precursor and / or support to generate plasma is a lower power, for example less than about 100 W. In some embodiments, the plasma is generated by an RF power source, such that the power is RF power. In some embodiments, the metal oxide resist sublayer is exposed to plasma for about 3 seconds to about 3600 seconds. In some embodiments, the pressure maintained in the process chamber during the plasma densification process is from about 0.1 Torr to about 150 Torr. In some embodiments, the temperature maintained in the process chamber during the plasma densification process is from about 25°C to about 300°C.

[0034] In some embodiments, a soft bake process (also referred to as an annealing process and / or a thermal process) heats workpiece 10 (including one or more metal oxide resist sublayers) for a period of time. The soft bake process may apply heat to the front side of workpiece 10 (e.g., the topmost metal oxide resist sublayer of workpiece 10), the bottom side of workpiece 10 (e.g., wafer 15), the sides of workpiece 10, or a combination thereof. In some embodiments, the soft bake process heats workpiece 10 to a temperature of about 80°C to about 250°C. In some embodiments, workpiece 10 is baked (annealed) for about 60 seconds to about 300 seconds. In some embodiments, the pressure maintained in the process chamber during the soft bake process is from about 0.1 Torr to about 150 Torr. In some embodiments, workpiece 10 is baked (annealed) in an inert gas environment (including, for example, argon, helium, and / or other inert gas components) or a reactive gas environment (including, for example, oxygen, hydrogen, nitrogen, and / or other reactive gas components).

[0035] In some embodiments, the UV irradiation process exposes one or more metal oxide resist sublayers of workpiece 10 to UV irradiation for a period of time. In some embodiments, the UV irradiation has a wavelength of about 10 nm to about 400 nm. In some embodiments, the metal oxide resist sublayer is exposed to UV irradiation for about 60 seconds to about 3600 seconds. In some embodiments, the UV irradiation process heats workpiece 10 to a temperature of about 20°C to about 25°C. In some embodiments, the pressure maintained in the process chamber during the UV irradiation process is about 1 × 10⁻⁶. -5 To about 1×10 -4 In some embodiments, UV radiation is used to treat the workpiece 10 in an inert gas environment (including, for example, argon, helium and / or other inert gas components) or a reactive gas environment (including, for example, oxygen, hydrogen, nitrogen and / or other reactive gas components).

[0036] In some embodiments, an infrared (IR) irradiation process exposes one or more metal oxide resist sublayers of workpiece 10 to IR radiation for a period of time. In some embodiments, the IR radiation has a wavelength greater than about 300 nm. In some embodiments, the IR radiation is far-infrared (FIR) radiation with a wavelength, for example, from about 50 μm to about 1000 μm. In some embodiments, the metal oxide resist sublayer is exposed to IR radiation for about 10 seconds to about 600 seconds. In some embodiments, the IR irradiation process heats workpiece 10 to a temperature of about 25°C to about 250°C. In some embodiments, the pressure maintained in the process chamber during the IR irradiation process is from about 0.1 Torr to about 150 Torr. In some embodiments, IR irradiation is used to treat workpiece 10 in an inert gas environment (including, for example, argon, helium, and / or other inert gas components) or a reactive gas environment (including, for example, oxygen, hydrogen, nitrogen, and / or other reactive gas components).

[0037] In some embodiments, a pre-deposition process is performed prior to deposition processes 50-1 to 50-4 to enhance adhesion between the metal oxide resist layer 40 and the material layer 20 and reduce peeling of the metal oxide resist layer 40 from the material layer 20. In some embodiments, the pre-deposition process is combined with deposition process 50-1. For example, the deposition stage may include a pre-deposition portion and a deposition portion, wherein deposition parameters are adjusted during deposition process 50-1 to switch from the pre-deposition portion to the deposition portion, such as the deposition precursor flow rate, power, time, and / or temperature. Deposition parameters of the pre-deposition portion may be adjusted to increase the chemical reaction (and thus the linking and / or bonding) between the deposition precursor and the material layer 20, thereby forming a material comprising a seed metal and oxygen on the material layer 20. Deposition parameters of the deposition portion may be adjusted to form a metal- and oxygen-containing material having the desired density characteristics for the metal oxide resist sublayer 40A. In such embodiments, the material comprising the seed metal and oxygen may form a portion of the metal oxide resist sublayer 40A. In some embodiments, the pre-deposition process is a plasma treatment process. This disclosure considers pre-deposition processes including any treatment that can be performed on workpiece 10 to increase adhesion to the metal oxide resist layer 40.

[0038] Deposition processes 50-1 to 50-4 and densification processes 52-1 to 52-4 are performed in situ. As used herein, the term "in situ" is used to describe processes performed while the workpiece is held within a processing system (e.g., a CVD tool), and wherein, for example, the processing system allows the workpiece to be held under vacuum conditions. Thus, the term "in situ" can also generally refer to processes in which the workpiece being processed is not exposed to the external environment (e.g., outside the processing system). Subsequent processing (e.g., exposure and development processes) can be performed non-in situ (i.e., workpiece 10 is removed from the CVD tool and transferred to an exposure tool and / or a development tool). In the depicted embodiment, deposition processes 50-1 to 50-4 and densification processes 52-1 to 52-4 are performed in the same process chamber of the processing system (e.g., a process chamber of the CVD tool). In some embodiments, deposition processes 50-1 to 50-4 are performed in the first process chamber of the multi-chamber processing system, densification processes 52-1 to 52-4 are performed in the second process chamber of the multi-chamber processing system, and the workpiece 10 is not exposed to the external environment and is kept under vacuum when it is transferred between the first process chamber and the second process chamber (and within the multi-chamber IC processing system 100) to form a metal oxide resist layer 40.

[0039] return Figure 1AAfter depositing metal oxide resist layers 30 and 40, photolithography processes A and B are performed to expose the metal oxide resist layers 30 and 40 to patterned radiation. In some embodiments, the patterned radiation has a wavelength of less than about 250 nm, such as DUV radiation, EUV radiation, and / or other suitable radiation. In the depicted embodiment, the patterned radiation is EUV radiation, for example, radiation with a wavelength of less than about 13.5 nm. In some embodiments, as depicted, the patterned radiation is provided using a mask 60 in which an IC pattern is defined, which can form an image of the IC pattern on the metal oxide resist layers 30 and 40. The mask 60 blocks, transmits, and / or reflects radiation to the metal oxide resist layers 30 and 40 depending on the mask pattern and / or mask type (e.g., binary mask, phase-shift mask, or EUV mask). Exposure processes can be performed in air, liquid (immersion lithography), or vacuum (e.g., when exposing workpiece 10 to EUV radiation and / or an electron beam). In some embodiments, the exposure process directly modulates radiation, such as an electron beam (e-beam) or an ion beam, according to the IC pattern, without the use of a mask such as mask 60.

[0040] Because the metal oxide resist layers 30 and 40 are sensitive to radiation, a latent pattern is formed on them through an exposure process. The latent pattern generally refers to the pattern exposed on the resist layer, which becomes a solid resist pattern after the resist layer undergoes a development process. Figure 1A In the embodiment, the implicit pattern of the metal oxide resist layer 30 includes exposed portions 30E and unexposed portions 30U, and the implicit pattern of the metal oxide resist layer 40 includes exposed portions 40E and unexposed portions 40U. The exposed portions 30E and 40E are physically and / or chemically altered in response to the exposure process. In the depicted embodiment, the exposure process induces a chemical reaction in the exposed portions 30E and 40E that reduces the solubility of the exposed portions 30E and 40E in the developer. In some embodiments, the exposed portions 30E and 40E are insoluble in the developer. In some embodiments, after the exposure process, a post-exposure baking (PEB) process is performed on the metal oxide resist layer 30 and / or the metal oxide resist layer 40. The PEB process raises the temperature of the metal oxide resist layer 30 and / or the metal oxide resist layer 40 to approximately 90°C to approximately 250°C. Because the metal oxide resist layer 40 has a dense and uniform atomic structure, while the metal oxide resist layer 30 has a loose and random atomic structure (see, for example, [reference needed]). Figure 1C (Top view of metal oxide resist layer 30 and metal oxide resist layer 40 after deposition) The exposure dose of patterned radiation projected onto metal oxide resist layer 40 can be less than the exposure dose of patterned radiation projected onto metal oxide resist layer 30. In some embodiments, the exposure dose of patterned radiation projected onto metal oxide resist layer 40 can be about one-tenth less than the exposure dose of patterned radiation projected onto metal oxide resist layer 30. Furthermore, in contrast to metal oxide resist layer 30, metal oxide resist layer 40: does not produce venting (or produces minimal venting) during the exposure process, PEB process, and / or other subsequent processes, thereby reducing (and in some embodiments preventing) film defects in the workpiece caused by venting contamination; and / or limiting (and in some embodiments preventing) the reduction in pattern fidelity over time caused by venting contamination accumulated in the process chamber when the workpiece is processed to form the metal oxide layer.

[0041] Then, photolithography processes A and B perform development processes on the metal oxide resist layer 30 and the metal oxide resist layer 40, respectively, to form patterned metal oxide resist layers 30' and 40'. The development process dissolves the exposed (or unexposed) portions of the metal oxide resist layers 30 and 40, respectively, based on the characteristics of the metal oxide resist layers 30 and 40 and the characteristics of the developing solution used in the development process. In the depicted embodiment, a negative tone development (NTD) process is performed to remove the unexposed portions 30U of the metal oxide resist layer 30 and 40. For example, an NTD developer is applied to metal oxide resist layer 30 and metal oxide resist layer 40, which dissolves the unexposed portions 30U and 40U, leaving a patterned metal oxide resist layer 30' with an opening 62 defined by an exposed portion 30E and a patterned metal oxide resist layer 40' with an opening 64 defined by an exposed portion 40E (each exposed portion 40E contains the corresponding remaining portions of metal oxide resist sublayers 40A-40D). After development, the patterned metal oxide resist layer 30' and the patterned metal oxide resist layer 40' have resist patterns corresponding to the IC pattern of the mask 30. Because the metal oxide resist layer 40 has a dense and uniform structure, while the metal oxide resist layer 30 has a loose and random structure, the metal oxide resist layer 40 absorbs patterned radiation more uniformly than the metal oxide resist layer 30, and the exposed portion 40E has relatively smooth edges and / or sidewalls compared to the exposed portion 30E of the metal oxide layer 30. Therefore, the patterned metal oxide resist layer 40' exhibits better LER / LWR and critical size uniformity than the patterned metal oxide resist layer 30', thus significantly improving lithography resolution. See, for example... Figure 1C A top view of the patterned metal oxide resist layer 30' and the patterned metal oxide resist layer 40' in the image.

[0042] This disclosure further discloses the use of a cyclic metal resist deposition process to control the density distribution and / or density characteristics of a metal oxide resist layer to obtain desired performance of the metal oxide resist layer and optimize specific patterning characteristics during patterning (i.e., exposure and development). In some embodiments, the number of cycles (i.e., the number of metal oxide sublayers), the thickness of each cycle (i.e., the thickness of the metal oxide sublayer), the density of each cycle (i.e., the density of the metal oxide sublayer), and / or the cycle time can be adjusted to obtain a desired density distribution, desired density characteristics, and / or desired optimized performance parameters of the metal oxide resist layer. In some embodiments, parameters of the deposition process (e.g., deposition processes 50-1 to 50-4) are adjusted to achieve the desired density distribution, desired density characteristics, and / or desired optimized performance parameters of the metal oxide resist sublayer. Deposition parameters may include the type of deposition precursor, the flow rate of the deposition precursor, the deposition pressure, the deposition temperature, the deposition power, the deposition time, other deposition parameters, or combinations thereof. In some embodiments, parameters of the densification process (e.g., densification processes 52-1 to 52-3) are adjusted to achieve a desired density distribution, desired density characteristics, and / or desired optimized performance parameters of the metal oxide resist sublayer. Densification parameters may include processing time, processing temperature, processing wavelength, processing power, processing precursor, processing precursor flow rate, other processing parameters, or combinations thereof.

[0043] Sometimes, during the exposure process, patterned radiation cannot uniformly expose the resist layer along its depth. For example, the top of the resist layer receives a higher exposure dose than the bottom. The absorption of exposure photons (e.g., EUV photons) decreases accordingly from top to bottom of the resist layer, reducing cross-linking within the resist layer from top to bottom. This phenomenon can be observed in photolithography process A, such as... Figure 2A As shown, the number of EUV photons (P) at the top portion of the exposed portion 30E of the metal oxide resist layer 30 is less than the number of EUV photons at the bottom portion of the exposed portion 30E of the metal oxide resist layer 30. Therefore, less chemical reaction (e.g., crosslinking) occurs in the bottom portion of the exposed portion 30E compared to the top portion, and the bottom portion of the exposed portion 30E is partially soluble (rather than insoluble) to the developer. As a result, the resist pattern defined by the exposed portion 30E exhibits a deviation (difference) in the top critical dimension (TCD) and the bottom critical dimension (BCD), thereby degrading the pattern fidelity provided by the patterned metal oxide resist layer 30'. In some embodiments, as shown, the exposed portion 30E has tapered sidewalls, wherein the width of the exposed portion 30E decreases from top to bottom, and the TCD of the exposed portion 30E is greater than the BCD of the exposed portion 30E.

[0044] Photolithography process C implements a cyclic metal resist deposition process B to provide a metal oxide resist layer 80 that addresses this phenomenon and optimizes the absorption of exposure photons (e.g., EUV photons) from top to bottom. The metal oxide resist layer 80 has a decreasing gradient density from bottom to top, for example, a decreasing gradient density from the bottom surface of the metal oxide layer 80 (e.g., at the junction with material layer 20) to the top surface of the metal oxide resist layer 80. For example, the cyclic metal resist deposition process B forms metal oxide resist sublayers 80A, 80B, and 80C, which are combined to form a metal oxide resist layer 80 with a thickness T. In contrast to the metal oxide resist layer 40 (where metal oxide resist sublayers 40A-40D have substantially the same density), the density of metal oxide resist sublayer 80A is greater than that of metal oxide resist sublayer 80B, and the density of metal oxide resist sublayer 80B is greater than that of metal oxide resist sublayer 80C, such that the density of the metal oxide resist layer 80 decreases from bottom to top. Configuring the metal oxide resist layer 80 (i.e., metal oxide resist sublayer 80C) to have a low-density top portion allows exposure photons to more easily pass through the metal oxide resist layer 80 and reach the bottom of the metal oxide layer 80, thus increasing the number of photons reaching the bottom portion of the metal oxide layer 80. Configuring the metal oxide resist layer 80 (i.e., metal oxide resist sublayer 80A) to have a high-density bottom portion increases the absorption of exposure photons by the bottom portion of the metal oxide resist layer 80. Therefore, the gradient density of the metal oxide resist layer 80 increases crosslinking in the bottom portion of the metal oxide resist layer 80. For example, during the exposure process, the amount of chemical reaction (e.g., crosslinking) in the bottom portion of the exposed portion 80E is substantially the same as the amount of chemical reaction in the top portion of the exposed portion 80E, making the exposed portion 80E uniformly (e.g., from top to bottom) insoluble in the developer, while the unexposed portion 80U remains soluble in the developer. As a result, after development, a resist pattern is provided by a patterned metal oxide resist layer 80' with openings 82 defined by the exposed portion 80E having minimal (or even no) deviation in the TCD and BCD (i.e., the TCD and BCD are substantially the same), thereby improving pattern fidelity. In some embodiments, as shown, the exposed portion 80E has substantially parallel sidewalls, and the width of the exposed portion 80E is substantially the same from top to bottom. In some embodiments, the low-density top portion of the metal oxide resist layer 80 has a loose, random, and / or non-uniform atomic structure, while the high-density bottom portion of the metal oxide resist layer 80 has a dense, ordered, and / or uniform atomic structure.

[0045] In some embodiments, the overall density (e.g., average density) of the metal oxide resist layer 80 is greater than the overall density (e.g., average density) of the metal oxide resist layer 30, such that when exposed to the same exposure dose, the metal oxide resist layer 80 absorbs more radiation than the metal oxide resist layer 30, and the metal oxide resist layer 80 absorbs this radiation more uniformly than the metal oxide resist layer 30. In the depicted embodiments, the densities of metal oxide resist sublayers 80A and 80B are greater than the density of metal oxide resist layer 30, while the density of metal oxide resist sublayer 80C is substantially equal to or less than the density of metal oxide resist layer 30. In some embodiments, the densities of metal oxide resist sublayers 80A-80C are all greater than the density of metal oxide resist layer 30. The metal oxide sublayers 80A-80C may have corresponding density distributions, such as a generally uniform density, a gradient density increasing or decreasing from the bottom surface to the top surface, an alternating density, or other suitable density distributions. In the illustrated embodiment, each metal oxide sublayer 80A-80C has a substantially uniform density. In some embodiments, the atomic structure of metal oxide resist sublayer 80A is more ordered and / or more compactly packed than the atomic structure of metal oxide resist sublayer 80B, and the atomic structure of metal oxide resist sublayer 80B is more ordered and / or more compactly packed than the atomic structure of metal oxide resist sublayer 80C. Metal oxide resist sublayers 80A-80C each have thicknesses t5, t6, and t7, where the sum of thicknesses t5, t6, and t7 equals the target thickness T. In the illustrated embodiment, thicknesses t5, t6, and t7 are substantially the same. In some embodiments, thicknesses t5, t6, and / or t7 may be different or the same, depending on the desired density distribution and / or density characteristics for the metal oxide resist layer 80.

[0046] Figure 2B A cyclic metal resist deposition process B according to various aspects of this disclosure is illustrated. Figure 2BIn the process, the cyclic metal resist deposition process B comprises three cycles, each cycle forming one of the metal oxide resist sublayers 80A-80C. Each cycle includes a deposition process, and some cycles include a densification process. For example, the cyclic metal resist deposition process B includes cycles 1, 2, and 3. Cycle 1 includes: performing a deposition process 90-1 to form a metal oxide resist sublayer 80A' having a thickness t5 and a first density on the material layer 20; and performing a densification process 92-1 on the metal oxide resist sublayer 80A' to form a metal oxide resist sublayer 80A having a second density greater than the first density. Cycle 2 includes: performing a deposition process 90-2 to form a metal oxide resist sublayer 80B' having a thickness t6 and a third density on the metal oxide resist sublayer 80A; and performing a densification process 92-2 on the metal oxide resist sublayer 80B' to form a metal oxide resist sublayer 80B having a fourth density, which is greater than the third density and less than the second density of the metal oxide resist sublayer 80A. Cycle 3 includes: performing a deposition process 90-3 to form a metal oxide resist sublayer 80C having a fifth density less than the fourth density. No densification process is performed during Cycle 3. Deposition processes 90-1 to 90-3 are similar to deposition processes 50-1 to 50-4 described above; densification processes 92-1 and 92-2 are similar to densification processes 52-1 to 52-4; and the parameters of deposition processes 90-1 to 90-3 and densification processes 92-1 and 92-2 can be configured to achieve the desired density distribution and / or desired density characteristics of the metal oxide resist sublayers 80A', 80B', metal oxide resist sublayers 80A-80C, and metal oxide resist layer 80. In the described embodiments, the second density, fourth density, and fifth density (i.e., the density of the metal and oxygen-containing resist material after each cycle) are different, such that the metal oxide resist layer 80 has a density that increases from top to bottom. In some embodiments, the first density, third density, and fifth density (i.e., the density of the deposited metal and oxygen-containing resist material) are substantially the same. In some embodiments, the first density, third density, and / or fifth density are different. In some embodiments, the first density, the third density, and / or the fifth density are the same as the density of the metal oxide resist layer 30.

[0047] Sometimes, during the exposure process, unexpected chemical reactions (such as crosslinking) occur in the unexposed portions of the resist layer. This phenomenon can be observed in photolithography process A, such as... Figure 3AAs shown, an undesirable and unintentional chemical reaction occurs in the portion of the metal oxide resist layer 30 covered by the mask 30 (i.e., the unexposed portion 30U), resulting in an unintentionally exposed portion UE that is partially insoluble (rather than soluble) in the developer. As a result, the unexposed portion 30U is not completely removed by the developer, leaving resist residue S in the unexposed area of ​​the workpiece 10. The resist residue S corresponds to the unintentionally exposed portion UE and may be resist scum (e.g., resist residue preventing the area of ​​material layer 20 from being patterned) and / or resist basalt (e.g., resist residue at the bottom of the exposed portion 30E), leading to critical dimension changes and / or LER / LWR changes. Figure 3A The photolithography process D described herein implements a cyclic metal resist deposition process C to provide a metal oxide resist layer 100 that addresses and minimizes this phenomenon.

[0048] The metal oxide resist layer 100 has a gradient density that increases from bottom to top, for example, from the bottom surface of the metal oxide layer 100 (e.g., where it intersects with material layer 20) to the top surface of the metal oxide resist layer 100. For example, a cyclic metal resist deposition process C forms metal oxide resist sublayers 100A, 100B, and 100C, which are combined to form a metal oxide resist layer 100 having a thickness T. In contrast to the metal oxide resist layer 40 (where metal oxide resist sublayers 40A-40D have substantially the same density), the density of metal oxide resist sublayer 100A is less than the density of metal oxide resist sublayer 100B, and the density of metal oxide resist sublayer 100B is less than the density of metal oxide resist sublayer 100C, such that the density of the metal oxide resist layer 100 increases from bottom to top. The metal oxide resist layer 100 (i.e., metal oxide resist sublayer 100A) is configured with a low-density bottom portion, which reduces the absorption of exposure photons in the bottom portion of the metal oxide resist layer 100, and thus reduces the frequency of accidental chemical reactions in the unexposed portions of the metal oxide resist layer 100. The metal oxide resist layer 100 (i.e., metal oxide resist sublayers 100B and 100C) is configured with a high-density top portion, which increases the absorption of exposure photons in the top portion of the metal oxide resist layer 100. Therefore, the gradient density of the metal oxide resist layer 100 reduces cross-linking in the bottom portion of the metal oxide resist layer 100 while increasing cross-linking in the top portion of the metal oxide resist layer 100. For example, in the exposure process, the amount of chemical reaction (e.g., crosslinking) in the bottom portion of the exposed portion 100E can be less than the amount of chemical reaction in the top portion of the exposed portion 100E, thereby reducing the frequency of accidental chemical reactions (e.g., partial crosslinking) in the unexposed portion 100U adjacent to the bottom portion of the exposed portion 100E. As a result, after development, a resist pattern is provided by a patterned metal oxide resist layer 100' having an opening 102 defined by the clearly defined exposed portion 100E, which has a minimal or no resist residue, thereby improving pattern fidelity. In some embodiments, as shown, the exposed portion 100E has substantially parallel sidewalls, and the width of the exposed portion 100E is substantially the same from top to bottom. In some embodiments, the low-density bottom portion of the metal oxide resist layer 100 has a loose, random, and / or non-uniform atomic structure, while the high-density top portion of the metal oxide resist layer 100 has a dense, ordered, and / or uniform atomic structure.

[0049] In some embodiments, the overall density (e.g., average density) of the metal oxide resist layer 100 is greater than the overall density (e.g., average density) of the metal oxide resist layer 30, such that when exposed to the same exposure dose, the metal oxide resist layer 100 absorbs more radiation than the metal oxide resist layer 30, and the metal oxide resist layer 80 absorbs this radiation more uniformly than the metal oxide resist layer 30. In the depicted embodiments, the densities of metal oxide resist sublayers 100C and 100B are greater than the density of the metal oxide resist layer 30, while the density of metal oxide resist sublayer 100A is substantially equal to or less than the density of the metal oxide resist layer 30. In a further improvement of the depicted embodiments, the density of metal oxide resist sublayer 100C is greater than the density of metal oxide resist sublayer 100B. In some embodiments, the densities of metal oxide resist sublayers 100C and 100B are substantially the same. In some embodiments, the densities of the metal oxide resist sublayers 100A–100C are all greater than the density of the metal oxide resist layer 30. The metal oxide sublayers 100A–100C may have corresponding density distributions, such as a generally uniform density, a gradient density increasing or decreasing from the bottom surface to the top surface, an alternating density, or other suitable density distributions. In the illustrated embodiment, each metal oxide sublayer 100A–100C has a generally uniform density. In some embodiments, the atomic structure of the metal oxide resist sublayer 100A is more disordered and / or less densely packed than the atomic structure of the metal oxide resist sublayer 100B, and the atomic structure of the metal oxide resist sublayer 100B is more disordered and / or less densely packed than the atomic structure of the metal oxide resist sublayer 100C. The metal oxide resist sublayers 100A–100C each have thicknesses t8, t9, and t10, wherein the sum of thicknesses t8, t9, and t10 is equal to the target thickness T. In the illustrated embodiment, thicknesses t8, t9, and t10 are substantially the same. In some embodiments, thicknesses t8, t9, and / or t10 may be different or the same, depending on the desired density distribution and / or density characteristics.

[0050] Figure 3B A cyclic metal resist deposition process C according to various aspects of this disclosure is illustrated. Figure 3BIn the cyclic metal resist deposition process C, there are three cycles, each forming one of the metal oxide resist sublayers 100A–100C. Each cycle includes a deposition process, and some cycles include a densification process. For example, the cyclic metal resist deposition process C includes cycles 1, 2, and 3. Cycle 1 includes performing deposition process 110-1 to form a metal oxide resist sublayer 100A on the material layer 20, which has a thickness t8 and a first density. No densification process is performed during cycle 1. Cycle 2 includes: performing a deposition process 110-2 to form a metal oxide resist sublayer 100B' having a thickness t9 and a second density on a metal oxide resist sublayer 100A; and performing a densification process 112-1 on the metal oxide resist sublayer 100B' to form a metal oxide resist sublayer 100B having a third density greater than the second density and the first density of the metal oxide resist sublayer 100A. Cycle 3 includes: performing a deposition process 110-3 to form a metal oxide resist sublayer 100C' having a thickness t10 and a fourth density; and performing a densification process 112-2 on the metal oxide resist sublayer 100C' to form a metal oxide resist sublayer 100C having a fifth density greater than the fourth density and the third density of the metal oxide resist sublayer 100B. Deposition processes 110-1 to 110-3 are similar to deposition processes 50-1 to 50-4 described above; densification processes 112-1 and 112-2 are similar to densification processes 52-1 to 52-4; and the parameters of deposition processes 110-1 to 110-3 and densification processes 112-1 and 112-2 can be configured to achieve the desired density distribution and / or desired density characteristics of the metal oxide resist sublayers 100B', 100C', metal oxide resist sublayers 100A-100C, and metal oxide resist layer 100. In the described embodiments, the first density, third density, and fifth density (i.e., the density of the metal and oxygen-containing resist material after each cycle) are different, such that the metal oxide resist layer 100 has a density that decreases from top to bottom. In some embodiments, the third density and the fifth density are the same, but in other embodiments, the third density and the fifth density are different and greater than the first density. In some embodiments, the first density, second density, and fourth density (i.e., the density of the deposited metal and oxygen-containing resist material) are substantially the same. In some embodiments, the first density, second density, and / or fourth density are different. In some embodiments, the first density, second density, and / or fourth density are the same as the density of the metal oxide resist layer 30.

[0051] Figure 4A cyclic metal resist deposition process D for forming a metal oxide resist layer 120 according to various aspects of this disclosure is illustrated. This metal oxide resist layer 120 can be used in a photolithography process to improve pattern fidelity. The metal oxide resist layer 120 has an alternating density (e.g., loose-dense-loose-dense) from bottom to top, for example, from the bottom surface of the metal oxide layer 120 (e.g., at the boundary with material layer 20) to the top surface of the metal oxide resist layer 120. For example, the cyclic metal resist deposition process D forms metal oxide resist sublayers 120A, 120B, 120C, and 120D, which are combined to form a metal oxide resist layer 120 having a thickness T. Metal oxide resist sublayers 120A–120D have thicknesses t11, t12, t13, and t14, respectively, wherein the sum of thicknesses t11, t12, t13, and t14 equals the target thickness T. In contrast to metal oxide resist layer 40 (where metal oxide resist sublayers 40A–40D have substantially the same density), the density of metal oxide resist sublayer 120B is greater than that of metal oxide resist sublayer 120A, the density of metal oxide resist sublayer 120C is less than that of metal oxide resist sublayer 120B, and the density of metal oxide resist sublayer 120D is greater than that of metal oxide resist sublayer 120C, such that the density of metal oxide resist layer 120 alternates from low to high from bottom to top and / or the atomic structure of metal oxide resist layer 120 alternates from loose to dense from bottom to top. Alternating density distributions can balance various patterning issues to optimize pattern fidelity. For example, configuring the metal oxide resist layer 120 with a low-density bottom portion (i.e., metal oxide resist sublayer 120A) reduces resist scum and / or resist foot defects, while configuring the metal oxide resist layer 120 with a high-density top portion (i.e., metal oxide resist sublayer 120D) minimizes exhaust emissions and thus minimizes exhaust pollution caused by the metal oxide resist layer 120. Furthermore, configuring the metal oxide resist layer 120 with a gradient density middle portion decreasing from top to bottom (i.e., metal oxide resist sublayers 120B and 120C) can enhance radiation absorption, thereby improving LER / LWR and / or critical size uniformity.

[0052] In some embodiments, the overall density (e.g., average density) of the metal oxide resist layer 120 is greater than the overall density (e.g., average density) of the metal oxide resist layer 30, such that when exposed to the same exposure dose, the metal oxide resist layer 120 absorbs more radiation than the metal oxide resist layer 30, and the metal oxide resist layer 120 absorbs this radiation more uniformly than the metal oxide resist layer 30. In the described embodiments, the density of metal oxide resist sublayers 120B-120D is greater than the density of metal oxide resist layer 30, while the density of metal oxide resist sublayer 120A is substantially equal to or less than the density of metal oxide resist layer 30. In some embodiments, the density of metal oxide resist sublayer 120D is the maximum density of metal oxide resist layer 120, the density of metal oxide resist sublayer 120A is the minimum density of metal oxide resist layer 120, and the density of the metal oxide resist sublayer 120A is between this maximum and minimum density. In some embodiments, the density of metal oxide resist sublayer 120B is the same as the density of metal oxide resist sublayer 120D. In some embodiments, the density of metal oxide resist sublayer 120B is less than the density of metal oxide resist sublayer 120D, but greater than the density of metal oxide resist sublayer 120C. In some embodiments, the densities of metal oxide resist sublayers 120A–120D are all greater than the density of metal oxide resist layer 30. Metal oxide sublayers 120A–120D may have corresponding density distributions, such as a generally uniform density, a gradient density increasing or decreasing from the bottom surface to the top surface, an alternating density, or other suitable density distributions. In the illustrated embodiment, each metal oxide sublayer 120A–120D has a generally uniform density.

[0053] exist Figure 4In the cyclic metal resist deposition process D, there are four cycles, each forming one of the metal oxide resist sublayers 120A–120D. Each cycle includes a deposition process, and some cycles include a densification process. For example, the cyclic metal resist deposition process D includes cycles 1, 2, 3, and 4. Cycle 1 includes performing deposition process 130-1 to form a metal oxide resist sublayer 130A on the material layer 20, which has a thickness t11 and a first density. No densification process is performed during cycle 1. Cycle 2 includes: performing a deposition process 130-2 to form a metal oxide resist sublayer 120B' having a thickness t12 and a second density on a metal oxide resist sublayer 120A; and performing a densification process 132-1 on the metal oxide resist sublayer 120B' to form a metal oxide resist sublayer 120B having a third density, which is greater than the second density and the first density of the metal oxide resist sublayer 120A. The thickness t12 is greater than the thickness t11. Cycle 3 includes: performing a deposition process 130-3 to form a metal oxide resist sublayer 120C' having a thickness t13 and a fourth density; and performing a densification process 132-2 on the metal oxide resist sublayer 120C' to form a metal oxide resist sublayer 120C having a fifth density, which is greater than the fourth density and less than the third density of the metal oxide resist sublayer 120B. Thickness t13 is less than thickness t12 and greater than thickness t11. Cycle 4 includes: performing a deposition process 130-4 to form a metal oxide resist sublayer 120D' having a thickness t14 and a sixth density; and performing a densification process 132-3 on the metal oxide resist sublayer 120D' to form a metal oxide resist sublayer 120D with a seventh density, which is greater than the sixth density and greater than the fifth density of the metal oxide resist sublayer 120C. Thickness t14 is less than thickness t13. In the illustrated embodiment, the seventh density is substantially the same as the third density. Deposition processes 130-1 to 130-4 are similar to the aforementioned deposition processes 50-1 to 50-4; densification processes 132-1–132-3 are similar to densification processes 52-1 to 52-4; and the parameters of deposition processes 130-1–130-4 and densification processes 132-1–132-3 can be configured to achieve the desired density distribution and / or desired density characteristics of the metal oxide resist sublayers 120B'–120D', 120A–120D, and 120. In the described embodiments, the first density, third density, fifth density, and seventh density (i.e., the density of the metal and oxygen-containing resist material after each cycle) are different, such that the metal oxide resist layer 120 has a density that varies from top to bottom.In some embodiments, the first density, second density, fourth density, and / or seventh density (i.e., the density of the deposited metal and oxygen-containing resist material) are substantially the same. In some embodiments, the first density, second density, and / or fourth density are different. In some embodiments, the first density, second density, fourth density, and / or sixth density are the same as the density of the metal oxide resist layer 30. For clarity, this has been simplified. Figure 4 To better understand the inventive concept of this disclosure. Other features may be added to the cyclic metal resist deposition process D, and some features described below may be replaced, modified, or eliminated in other embodiments of the cyclic metal resist deposition process D.

[0054] Figure 5 A cyclic metal resist deposition process E for forming a metal oxide resist layer according to various aspects of this disclosure is illustrated. This metal oxide resist layer can be used in a photolithography process to improve pattern fidelity. The cyclic metal resist deposition process E is similar to the cyclic metal resist deposition process A, except that the cyclic metal resist deposition process E forms a metal oxide resist layer 140 and modulates the densification process to induce partial crosslinking in the metal oxide resist layer 140. For example, the metal oxide resist layer 140 is uniformly and partially crosslinked from bottom to top, for example, from the bottom surface of the metal oxide layer 140 (e.g., at the junction with material layer 20) to the top surface of the metal oxide resist layer 140. The degree of crosslinking in the metal oxide resist layer 140 is greater than that in the metal oxide resist layer 130 (which can be zero), allowing the metal oxide resist layer 140 to be patterned with a smaller exposure dose than that required for the metal oxide resist layer 30. Figure 5 In the process, a cyclic metal resist deposition process E forms metal oxide resist sublayers 140A, 140B, 140C, and 140D, which are combined to form a metal oxide resist layer 140 with a thickness T. The metal oxide resist sublayers 140A-140D have thicknesses t1, t2, t3, and t4, respectively, wherein the sum of thicknesses t1, t2, t3, and t4 equals the target thickness T. The degree of partial crosslinking in metal oxide resist sublayers 140A, 140B, 140C, and 140D is substantially the same. In the illustrated embodiment, thicknesses t1, t2, t3, and t4 are substantially the same. In some embodiments, thicknesses t1, t2, t3, and / or t4 may be different or the same, depending on the desired partial crosslinking distribution. For clarity, simplified figures have been provided. Figure 5 To better understand the inventive concept of this disclosure. Other features may be added to the cyclic metal resist deposition process E, and some features described below may be replaced, modified, or eliminated in other embodiments of the cyclic metal resist deposition process E.

[0055] Go to Figure 5 As shown, the cyclic metal resist deposition process E comprises four cycles, each cycle forming one of the metal oxide resist sublayers 140A–140D, and each cycle includes a deposition process and a densification process. For example, the cyclic metal resist deposition process E includes cycles 1, 2, 3, and 4, wherein cycles 1–4 include deposition processes 50-1 to 50-4, respectively forming metal oxide resist sublayers 40A'–40D', as referenced above. Figures 1A to 1C The process is as follows: Cycle 1 includes performing a densification process 152-1 to induce crosslinking in the metal oxide resist sublayer 40A', thereby providing a metal oxide resist sublayer 140A with a first degree of crosslinking. Cycle 2 includes performing a densification process 152-2 to induce crosslinking in the metal oxide resist sublayer 40B', thereby providing a metal oxide resist sublayer 140B with a second degree of crosslinking. Cycle 3 includes performing a densification process 152-3 to induce crosslinking in the metal oxide resist sublayer 40C', thereby providing a metal oxide resist sublayer 140C with a third degree of crosslinking. Cycle 4 includes performing a densification process 152-4 to induce crosslinking in the metal oxide resist sublayer 40D', thereby providing a metal oxide resist sublayer 140D with a fourth degree of crosslinking. The first degree of crosslinking, the second degree of crosslinking, the third degree of crosslinking, and the fourth degree of crosslinking are less than complete crosslinking. In the illustrated embodiments, the first, second, third, and fourth degrees of crosslinking are substantially the same, which can be achieved by adjusting the parameters of densification processes 152-1 to 152-4. In some embodiments, the first, second, third, and fourth degrees of crosslinking are different or the same to achieve metal oxide resist layers with different crosslinking distributions. In some embodiments, the metal oxide resist layer 140 has a crosslinking degree that varies from top to bottom. For example, the first degree of crosslinking is greater than the second, third, and / or fourth degree of crosslinking. Densification processes 152-1 to 152-4 are similar to the densification processes described above. For example, densification processes 152-1 to 152-4 may be soft baking, UV treatment, IR treatment / other suitable treatments, or combinations thereof.

[0056] After performing the various photolithography processes described herein (e.g., photolithography process A, photolithography process B, photolithography process C, and / or photolithography process D), a manufacturing process is performed on the workpiece 10 (e.g., material layer 20 and / or wafer 15) using a patterned metal oxide resist layer described herein (e.g., patterned metal oxide resist layer 30', patterned metal oxide resist layer 40', patterned metal oxide resist layer 80', patterned metal oxide resist layer 100', patterned metal oxide resist layer formed by metal oxide photoresist layer 120, and / or patterned metal oxide resist layer formed by metal oxide resist layer 140) as a mask. For example, the manufacturing process is applied only to the portion of the workpiece 10 within the opening of the patterned metal oxide resist layer, while other portions of the workpiece 10 covered by the patterned metal oxide resist layer (e.g., covered by the exposed portion of the patterned metal oxide resist layer) are protected from the manufacturing process. In some embodiments, the manufacturing process includes etching material layer 20 using a patterned metal oxide resist layer as an etch mask. Thus, a pattern is transferred from the patterned metal oxide resist layer to material layer 20, thereby forming a patterned material layer. In embodiments where material layer 20 is a hard mask layer, the pattern is first transferred from the patterned metal oxide resist layer to material layer 20, and then the pattern is transferred from the patterned material layer 20 to the material layer of wafer 15. In some embodiments, the manufacturing process includes performing an implantation process on material layer 20 using a patterned metal oxide resist layer as an implantation mask, thereby forming various doped features (regions) in material layer 20. In some embodiments, the manufacturing process includes depositing material on material layer 20 using a patterned metal oxide resist layer as a deposition mask, thereby forming various material features (e.g., gates and / or contacts) on material layer 20. Thereafter, the patterned metal oxide resist layer is removed from workpiece 10 using any suitable process. In some embodiments, the patterned metal oxide resist layer may be partially consumed during the manufacturing process (e.g., during the etching process), such that any remaining portion of the patterned metal oxide resist layer is subsequently removed by an appropriate process.

[0057] This disclosure provides metal oxide resist layers, a cyclic metal oxide resist deposition process for forming metal oxide resist layers, and lithography techniques using metal oxide resist layers to improve lithographic resolution and / or resist pattern fidelity. This disclosure contemplates that the cyclic metal oxide resist deposition process described herein can be implemented to form any type of metal-containing resist layer, such as a metal nitride resist layer, a metal carbide resist layer, and / or any other type of metal-containing photosensitive layer. In such embodiments, references to oxygen / oxide can be replaced with references to other components, such as nitrogen / nitride, carbon / carbide, and / or other metal-containing resist components. In such embodiments, the metal-containing resist layer may or may not include oxygen. The advanced lithography processes, methods, and materials described above can be used in many applications, including FinFET and / or GAA transistors. For example, fins can be patterned to create relatively close spacing between features, and the above disclosure is well-suited for such spacing. Furthermore, spacers (also referred to as mandrels) used to form fins can be processed according to the above disclosure.

[0058] An exemplary method includes: forming a metal oxide resist layer on a workpiece by performing a deposition process to form a metal oxide resist sublayer on the workpiece; and performing a densification process on at least one metal oxide resist sublayer. Each deposition process forms a corresponding one of the metal oxide resist sublayers. The densification process increases the density of at least one metal oxide resist sublayer. Parameters of the deposition process and / or the densification process can be adjusted to achieve different density distributions, different density characteristics, and / or different absorption characteristics, thereby optimizing the patterning of the metal oxide resist layer. In some embodiments, forming the metal oxide resist layer further includes performing a cleaning process after performing the densification process. In some embodiments, the deposition process and the densification process are performed in the same process chamber. In some embodiments, performing the densification process includes exposing at least one metal oxide resist sublayer to plasma. In some embodiments, performing the densification process includes soft baking at least one metal oxide resist sublayer. In some embodiments, performing the densification process includes exposing at least one metal oxide resist sublayer to ultraviolet (UV) radiation. In some embodiments, performing a densification process includes exposing at least one of the metal oxide resist sublayers to infrared (IR) radiation. In some embodiments, the densification process is performed after each deposition cycle, such that each metal oxide resist sublayer undergoes a corresponding densification treatment. In some embodiments, the method further includes adjusting deposition parameters of the deposition process, adjusting densification parameters of the densification process, or adjusting both deposition parameters of the deposition process and densification parameters of the densification process to achieve a gradient density in the metal oxide resist layer. In some embodiments, the method further includes performing an exposure process on the metal oxide resist layer and a development process on the metal oxide resist layer to form a patterned metal oxide resist layer on a workpiece.

[0059] Another exemplary method includes: receiving a workpiece in a process chamber; performing at least two deposition processes in the process chamber to form a metal oxide resist layer on the workpiece; and performing a processing process in the process chamber to modify the density distribution of the metal oxide resist layer. In some embodiments, the processing process is performed after each of the at least two deposition processes, such that the metal oxide resist layer has a uniform density from bottom to top. In some embodiments, the processing process is performed after each of the at least two deposition processes, such that the metal oxide resist layer has a density that varies from bottom to top. In some embodiments, the processing process is performed after at least one of the at least two deposition processes, such that the metal oxide resist layer has a gradient density that increases from bottom to top. In some embodiments, the processing process is performed after at least one of the at least two deposition processes, such that the metal oxide resist layer has a gradient density that decreases from bottom to top. In some embodiments, the processing process is performed after at least one of the at least two deposition processes, such that the metal oxide resist layer has an alternating density.

[0060] An exemplary metal oxide resist layer includes: a first metal oxide resist sublayer, a second metal oxide resist sublayer disposed above the first metal oxide resist sublayer, and a third metal oxide resist sublayer disposed above the second metal oxide resist sublayer. The first metal oxide resist sublayer has a first density, the second metal oxide resist sublayer has a second density, and the third metal oxide resist sublayer has a third density. In some embodiments, the first density, second density, and third density are substantially the same. In some embodiments, the first density, second density, and third density are different. In some embodiments, the first density, second density, and third density are configured to provide a gradient density for the metal oxide resist layer from the first metal oxide resist sublayer to the third metal oxide resist sublayer.

[0061] Another exemplary method includes: forming a metal oxide resist layer on a workpiece by performing a deposition process comprising more than one deposition cycle, such that the metal oxide resist layer contains a stack of metal oxide resist sublayers, and performing a densification process on at least one of the metal oxide resist sublayers, wherein the densification process increases the density of at least one of the metal oxide resist sublayers. In some embodiments, the deposition process and the densification process are performed in the same process chamber. In some embodiments, performing the densification process includes: exposing at least one metal oxide resist sublayer to plasma. In some embodiments, performing the densification process includes: exposing at least one metal oxide resist sublayer to an annealing process. In some embodiments, performing the densification process includes: exposing at least one metal oxide resist sublayer to ultraviolet (UV) radiation. In some embodiments, performing the densification process includes: exposing at least one of the metal oxide resist sublayers to infrared (IR) radiation. In some embodiments, the deposition process is a chemical vapor deposition process, an atomic layer deposition process, or a combination thereof. In some embodiments, a densification process is performed after each deposition cycle, such that each metal oxide resist sublayer in the stack of metal oxide resist sublayers undergoes a corresponding densification treatment. In some embodiments, the method further includes: adjusting the execution of the deposition process, adjusting the execution of the densification process, or adjusting both the execution of the deposition process and the densification process to achieve a gradient density in the metal oxide resist layers. In some embodiments, a first density of the topmost metal oxide resist sublayer of the stack of metal oxide resist sublayers is greater than a second density of the bottommost metal oxide resist sublayer of the stack of metal oxide resist sublayers. In some embodiments, a first density of the topmost metal oxide resist sublayer of the stack of metal oxide resist sublayers is less than a second density of the bottommost metal oxide resist sublayer of the stack of metal oxide resist sublayers. In some embodiments, adjusting the execution of the deposition process includes: adjusting the precursor gas, precursor gas flow rate, deposition pressure, deposition temperature, deposition power, deposition time, other deposition parameters, or combinations thereof. In some embodiments, adjusting the execution of the densification process includes: adjusting the processing time, processing power, processing temperature, other processing parameters, or combinations thereof. In some embodiments, the method further includes: adjusting the execution of a deposition process, adjusting the execution of a densification process, or adjusting both the execution of a deposition process and a densification process to obtain an alternating density pattern in the stack of metal oxide resist sublayers. In some embodiments, the method further includes: performing a cleaning process after performing a densification process. In some embodiments, the densification process is a first densification process, and the method further includes: performing a second densification process before forming a metal oxide resist layer on the workpiece.In some embodiments, the method further includes performing an exposure process on the metal oxide resist layer and a development process on the metal oxide resist layer to form a patterned metal oxide resist layer on a workpiece. In some embodiments, the densification process is a first densification process, and the method further includes performing an exposure process that includes exposing the metal oxide resist layer to patterned extreme ultraviolet (EUV) radiation. In some embodiments, the method further includes performing an etching process, an implantation process, or a deposition process on the workpiece using the patterned metal oxide resist layer as an etching mask, an implantation mask, or a deposition mask, respectively. In some embodiments, the method includes removing the patterned metal oxide resist layer after the etching process, the implantation process, or the deposition process. In some embodiments, the method further includes transferring a pattern in the patterned metal oxide resist layer to a sacrificial layer disposed on the workpiece to form a patterned sacrificial layer, and transferring a pattern in the patterned sacrificial layer to a material layer of the workpiece. In some embodiments, the method further includes performing a densification process on the workpiece before forming the metal oxide resist layer.

[0062] The foregoing outlines features of some embodiments to enable those skilled in the art to better understand various aspects of this disclosure. Those skilled in the art will recognize that they can readily use this disclosure as a basis for designing or modifying other processes and structures for performing the same purposes and / or achieving the same advantages of the embodiments described herein. Those skilled in the art should also realize that these equivalent constructions do not depart from the spirit and scope of this disclosure, and that they can be modified, substituted, and altered in various ways without departing from the spirit and scope of this disclosure.

[0063] Example

[0064] Example 1. A method for forming a semiconductor structure, comprising: forming a metal oxide resist layer on a workpiece by: performing a deposition process to form metal oxide resist sublayers of the metal oxide resist layer on the workpiece, wherein each deposition process forms a corresponding one metal oxide resist sublayer among the metal oxide resist sublayers; and performing a densification process on at least one metal oxide resist sublayer among the metal oxide resist sublayers, wherein the densification process increases the density of the at least one metal oxide resist sublayer among the metal oxide resist sublayers.

[0065] Example 2. According to the method of Example 1, wherein forming the metal oxide resist layer further includes performing a cleaning process after performing the densification process.

[0066] Example 3. The method according to Example 1, wherein the deposition process and the densification process are performed in the same process chamber.

[0067] Example 4. The method according to Example 1, wherein performing the densification process includes: exposing at least one metal oxide resist sublayer in the metal oxide resist sublayer to plasma.

[0068] Example 5. The method according to Example 1, wherein performing the densification process includes: soft baking of the at least one metal oxide resist sublayer in the metal oxide resist sublayer.

[0069] Example 6. The method according to Example 1, wherein performing the densification process includes: exposing at least one metal oxide resist sublayer in the metal oxide resist sublayer to ultraviolet (UV) radiation.

[0070] Example 7. The method according to Example 1, wherein performing the densification process includes: exposing at least one metal oxide resist sublayer in the metal oxide resist sublayer to infrared (IR) radiation.

[0071] Example 8. The method according to Example 1, wherein the densification process is performed after each deposition cycle, such that each metal oxide resist sublayer in the metal oxide resist sublayer undergoes a corresponding densification treatment.

[0072] Example 9. The method according to Example 1 further includes: adjusting the deposition parameters of the deposition process, adjusting the densification parameters of the densification process, or adjusting both the deposition parameters of the deposition process and the densification parameters of the densification process to achieve a gradient density in the metal oxide resist layer.

[0073] Example 10. The method of claim 1 further comprises: performing an exposure process on the metal oxide resist layer; and performing a development process on the metal oxide resist layer to form a patterned metal oxide resist layer on the workpiece.

[0074] Example 11. A method for forming a semiconductor structure, comprising: receiving a workpiece in a process chamber; performing at least two deposition processes in the process chamber to form a metal oxide resist layer on the workpiece; and performing a processing process in the process chamber to modify the density distribution of the metal oxide resist layer.

[0075] Example 12. The method according to Example 11, wherein the processing is performed after each of the at least two deposition processes, such that the metal oxide resist layer has a uniform density from bottom to top.

[0076] Example 13. The method according to Example 11, wherein the processing is performed after each of the at least two deposition processes, such that the metal oxide resist layer has a density that varies from bottom to top.

[0077] Example 14. The method according to Example 11, wherein the processing is performed after at least one of the at least two deposition processes, such that the metal oxide resist layer has a gradient density that increases from bottom to top.

[0078] Example 15. The method according to Example 11, wherein the processing is performed after at least one of the at least two deposition processes, such that the metal oxide resist layer has a gradient density that decreases from bottom to top.

[0079] Example 16. The method according to Example 11, wherein the processing is performed after at least one of the at least two deposition processes, such that the metal oxide resist layer has an alternating density.

[0080] Example 17. A metal oxide resist layer, comprising: a first metal oxide resist sublayer having a first density; a second metal oxide resist sublayer disposed on top of the first metal oxide resist sublayer, wherein the second metal oxide resist sublayer has a second density; and a third metal oxide resist sublayer disposed on top of the second metal oxide resist sublayer, wherein the third metal oxide resist sublayer has a third density.

[0081] Example 18. The metal oxide resist layer according to Example 17, wherein the first density, the second density, and the third density are substantially the same.

[0082] Example 19. The metal oxide resist layer according to Example 17, wherein the first density, the second density, and the third density are different.

[0083] Example 20. A metal oxide resist layer according to Example 17, wherein the first density, the second density and the third density are configured to provide a gradient density for the metal oxide resist layer from the first metal oxide resist sublayer to the third metal oxide resist sublayer.

Claims

1. A method for forming a semiconductor structure, comprising: A metal oxide resist layer is formed on the workpiece through the following operations: Perform a deposition process to form metal oxide resist sublayers of the metal oxide resist layer on the workpiece, wherein each deposition process forms a corresponding metal oxide resist sublayer within the metal oxide resist sublayers; and A densification process is performed on at least one of the metal oxide resist sublayers, wherein the densification process increases the density of the at least one metal oxide resist sublayer.

2. The method according to claim 1, wherein, The formation of the metal oxide resist layer also includes performing a cleaning process after the densification process.

3. The method according to claim 1, wherein, The deposition process and the densification process are performed in the same process chamber.

4. The method according to claim 1, wherein, Performing the densification process includes exposing at least one of the metal oxide resist sublayers to plasma.

5. The method according to claim 1, wherein, Performing the densification process includes: soft baking of at least one of the metal oxide resist sublayers.

6. The method according to claim 1, wherein, Performing the densification process includes exposing at least one of the metal oxide resist sublayers to ultraviolet (UV) radiation.

7. The method according to claim 1, wherein, Performing the densification process includes exposing at least one of the metal oxide resist sublayers to infrared (IR) radiation.

8. The method according to claim 1, wherein, The densification process is performed after each deposition cycle, so that each metal oxide resist sublayer in the metal oxide resist sublayer undergoes a corresponding densification treatment.

9. The method according to claim 1, further comprising: Adjust the deposition parameters of the deposition process, adjust the densification parameters of the densification process, or adjust both the deposition parameters of the deposition process and the densification parameters of the densification process to achieve a gradient density in the metal oxide resist layer.

10. The method according to claim 1, further comprising: An exposure process is performed on the metal oxide resist layer; as well as A development process is performed on the metal oxide resist layer to form a patterned metal oxide resist layer on the workpiece.

11. A method for forming a semiconductor structure, comprising: Receive workpieces in the process room; At least two deposition processes are performed in the process chamber to form a metal oxide resist layer on the workpiece; as well as A processing procedure is performed in the process chamber to modify the density distribution of the metal oxide resist layer.

12. The method according to claim 11, wherein, The processing is performed after each of the at least two deposition processes, such that the metal oxide resist layer has a uniform density from bottom to top.

13. The method according to claim 11, wherein, The processing is performed after each of the at least two deposition processes, such that the metal oxide resist layer has a density that varies from bottom to top.

14. The method according to claim 11, wherein, The processing is performed after at least one of the at least two deposition processes, such that the metal oxide resist layer has a gradient density that increases from bottom to top.

15. The method according to claim 11, wherein, The processing is performed after at least one of the at least two deposition processes, such that the metal oxide resist layer has a gradient density that decreases from bottom to top.

16. The method according to claim 11, wherein, The processing is performed after at least one of the at least two deposition processes, such that the metal oxide resist layer has an alternating density.

17. A metal oxide resist layer, comprising: A first metal oxide resist sublayer, the first metal oxide resist sublayer having a first density; A second metal oxide resist sublayer is disposed on top of the first metal oxide resist sublayer, wherein the second metal oxide resist sublayer has a second density; and A third metal oxide resist sublayer is disposed on top of the second metal oxide resist sublayer, wherein the third metal oxide resist sublayer has a third density. Each of the first metal oxide resist sublayer, the second metal oxide resist sublayer, and the third metal oxide resist sublayer has an atomic structure of metal-oxygen components arranged in an ordered stack.

18. The metal oxide resist layer according to claim 17, wherein, The first density, the second density, and the third density are substantially the same.

19. The metal oxide resist layer according to claim 17, wherein, The first density, the second density, and the third density are different.

20. The metal oxide resist layer according to claim 17, wherein, The first density, the second density, and the third density are configured to provide a gradient density for the metal oxide resist layer from the first metal oxide resist sublayer to the third metal oxide resist sublayer.

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