Photoresist for the production of semiconductors

Abstract

Organometallic precursor in an EUV photoresist comprising chemical formula MaXbLcum, where M is a metal, where X is a multidentate aromatic ligand comprising a pyrrole-like nitrogen and a pyridine-like nitrogen, where L is a cleavage-in-the-extreme ultraviolet (EUV) ligand, where a is between 1 and 2, where b is equal to or greater than 1, and where c is equal to or greater than 1.

Description

PRIORITY DATA

[0001] This application claims priority over the preliminary US patent application No. 63 / 085,364 filed on September 30, 2020, the entire disclosure of which is hereby incorporated by reference. BACKGROUND

[0002] The integrated semiconductor (IC) circuit industry has experienced exponential growth. Technological advances in IC materials and design have produced generations of ICs, each generation featuring smaller and more complex circuits than the previous one. Throughout IC evolution, functional density (i.e., the number of interconnected components per unit area of ​​the chip) has generally increased, while geometric size (i.e., the smallest component (or line) that can be produced using a manufacturing process) has decreased. This miniaturization process generally offers advantages by increasing production efficiency and reducing associated costs. However, such miniaturization has also increased the complexity of IC processing and manufacturing, and similar advancements in IC processing and fabrication are necessary to realize these improvements.

[0003] In one exemplary aspect, photolithography is a process used in semiconductor microfabrication to selectively remove portions of a material layer. The process uses a radiation source to transfer a structure (e.g., a geometric pattern) from a photomask to a photosensitive layer (e.g., a photoresist layer) on the material layer. The radiation causes a chemical change (e.g., increasing or decreasing solubility) in exposed areas of the photosensitive layer. Heating processes can be performed before and / or after exposure, for example, in a pre-exposure and / or post-exposure heating process. A development process then selectively removes the exposed or unexposed areas with a developer solution that creates an exposure pattern in the material layer.To improve the resolution of the photolithography process for high-density integrated circuits (ICs), radiation sources with shorter wavelengths have been developed. One such source is an extreme ultraviolet (EUV) radiation source. Although existing EUV photoresists are generally suitable for their intended purpose, they are not entirely satisfactory. Further improvements are desirable. List of characters

[0004] The present disclosure is best understood from the following detailed description when read together with the accompanying figures. It is emphasized that, in accordance with common industry practice, the various features are not drawn to scale and are for illustrative purposes only. Indeed, the dimensions of the various features may be arbitrarily increased or decreased for the sake of clarity of discussion. Fig. Figure 1 schematically shows a molecular structure of a metal-organic precursor according to various aspects of the present disclosure. Fig. 2A and Fig. Figure 2B schematically shows representative structures of a multidentate aromatic ligand of the organometallic precursor in Fig. 1, according to various aspects of the present revelation. Fig. Figure 3 illustrates exemplary multidentate aromatic ligands with a ring of the organometallic precursor in Fig. 1 according to various aspects of the present revelation. Fig. Figure 4 shows an example of multi-ring, multi-dentate aromatic ligands of the organometallic precursor in Fig. 1 according to various aspects of the present revelation. Fig. Figure 5 shows an example of EUV-fissile ligands of the metal-organic precursor in Fig. 1 according to various aspects of the present revelation. Fig. Figure 6 shows the metal-organic precursor in Fig. 1, which undergoes a reduction reaction according to various aspects of the present disclosure. Fig. shows an example of an organic metallic precursor undergoing a reduction reaction according to various aspects of the present disclosure. Fig. Figure 8 shows a flowchart of a process 200 for structuring a workpiece according to various aspects of the present disclosure. Fig. Figures 9-15 show fragmentary cross-sectional views of a workpiece that has undergone various steps of the 200 process. Fig. 8, according to various aspects of the present revelation. Fig. shows an example mechanism for a metal-organic precursor according to the present disclosure, which coordinates to a functional group on a material layer, according to various aspects of the present disclosure. DETAILED DESCRIPTION

[0005] The following disclosure provides many different embodiments or examples of the implementation of various features of the provided subject matter. To simplify the present disclosure, specific examples of components and arrangements are described below. These are, of course, only examples and are not intended to be limiting. For example, the formation of a first feature above or on top of a second feature in the following description may include embodiments in which the first and second features are in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, so that the first and second features do not have to be in direct contact. Furthermore, the present disclosure may repeat reference numbers and / or letters in the various examples.This repetition serves for simplicity and clarity and does not in itself represent a relationship between the various designs and / or configurations discussed.

[0006] Spatially relative terms such as "under," "below," "below," "above," "above," and the like can be used here to simplify the description and describe the relationship of one element or feature to another, as illustrated in the figures. These spatially relative terms are intended to encompass not only the orientation shown in the figures but also other orientations of the device in use or operation. The device may be oriented differently (rotated by 90 degrees or in other orientations), and the spatially relative terms used here can be interpreted accordingly.

[0007] When a number or range of numbers is described as "approximately," "about," or similar, the term is intended to include numbers that lie within a reasonable range, taking into account variations that naturally occur during manufacturing, as understood by a person skilled in the art. For example, the number or range of numbers includes a reasonable range encompassing the described number, such as within ±10% of the described number, based on known manufacturing tolerances associated with producing a feature with a property associated with the number. For example, a material layer with a thickness of "about 5 nm" may encompass a dimensional range from 4.25 nm to 5.75 nm, with manufacturing tolerances associated with applying the material layer being known to a person skilled in the art and amounting to ±15%.Furthermore, it may occur in the present disclosure that reference numbers and / or letters are repeated in the various examples. This repetition serves the purpose of simplicity and clarity and does not in itself represent a relationship between the various embodiments and / or configurations discussed.

[0008] The present disclosure relates generally to EUV photolithography and in particular to metal-organic precursors in EUV photoresists.

[0009] Some existing EUV photoresists exist as a solution comprising a cation species and an anion species. The anion species comprises a metal ion coordinated to EUV-stable ligands and bridging ligands. The bridging ligands act as crosslinkers to another metal ion. Exemplary bridging ligands in some existing EUVs can be an oxalate ion (C₂O₄). 2-These EUV photoresists exhibit poor adhesion to various surfaces. To improve adhesion, surface treatments or adhesion-promoting layers are required to ensure satisfactory bonding. Examples of adhesion-promoting layers include hexamethyl disilances (HMDS). Furthermore, because the bridging ligands are both EUV-cleavable and crosslinkers, it is difficult to control the EUV-induced crosslinking process effectively. On the one hand, some bridging ligands must be cleaved from the metal ions to create uncoordinated sites for crosslinking. On the other hand, some bridging ligands must remain coordinated to the metal ions to act as crosslinkers. If no bridging ligands are cleaved, or if all of them are, the crosslinking may be unsatisfactory.

[0010] The present disclosure provides a metal-organic precursor in a photoresist that can adhere well to various surfaces and crosslink in a well-controlled manner without surface treatments or adhesion-enhancing layers. The metal-organic precursor of the present disclosure comprises a metal ion coordinated to a variety of multidentate aromatic ligands and a variety of EUV-cleavable ligands. The multidentate aromatic ligand comprises a conjugation structure, a pyrrole-like nitrogen, and a pyridine-like nitrogen. The EUV-cleavable ligand comprises an alkenyl group or a carboxylate group. Each of the multidentate aromatic ligands is coordinated to the metal ion via the pyrrole-like nitrogen.When the organometallic precursor is irradiated with EUV radiation, the pyrrole-like nitrogen atoms of the multidentate aromatic ligands are activated, and the EUV-cleavable ligands are cleaved from the metal ion. The activated pyrrole-like nitrogen can coordinate to another metal ion at coordinate sites freed by the cleavage of the EUV-cleavable ligands. The metal ions have a high atomic absorption cross-section, so available coordination sites can be used to bind to various functional groups on the surface. The mode and degree of crosslinking can be precisely controlled by adjusting the stoichiometry ratio of the EUV-cleavable ligands to the multidentate aromatic ligands.

[0011] Fig. Figure 1 shows a schematic molecular structure of an organometallic precursor 100 according to aspects of the present disclosure. The organometallic precursor 100 comprises a metal ion (M) 102, a plurality of multidentate aromatic ligands (X) 104 coordinated to the metal ion 102, and a plurality of EUV cleavable ligands (L) 106 coordinated to the metal ion 102. Alternatively, the organometallic precursor 100 can also be described as M a X b L cThe numbers 102, 106, 106, 106, 106, 106, 106, 106, 106, 106, 106, 106, 106, 106, 106, 106, 106, 106, 106, 106, 106, 106, 106, 106, and 1, respectively. The sum of 106 and 106 is less than the available coordination sites of the metal ion 102 to leave at least one non-coordinated site to improve adhesion. If the organometallic precursor 100 is contained in a photoresist and the photoresist is to be deposited on a layer of material, the at least one non-coordinated site can bind to a functional surface group, such as a hydroxyl group on a silicon oxide layer or a metal oxide layer, or an amine group on a silicon nitride layer.The at least one uncoordinated site of the organometallic precursor 100 enables good adhesion without surface treatment or an additional adhesive layer. The metal ion 102 can comprise a metal exhibiting a high atomic absorption cross-section. Examples of the metal ion 102 include tin (Sn), bismuth (Bi), antimony (Sb), indium (In), or tellurium (Te). Since the metal ion 102 can have six (6) coordination sites, the sum of 'b' and 'c' (i.e., the total number of EUV cleavable ligands (L) 106 and the multidentate aromatic ligand (X) 104) must not exceed 5 to ensure that at least one unsaturated site (i.e., one uncoordinated site) remains. Unlike some existing organometallic precursors that exist in ionic forms and are stabilized by a counterion, the organometallic precursor 100 is charge-neutral.In some embodiments, the metal-organic precursor 100 of the present disclosure can be prepared ex-situ and then deposited onto a semiconductor device workpiece using spin coating. In some other embodiments, the metal-organic precursor 100 can be deposited onto a semiconductor device workpiece by chemical vapor deposition (CVD) or atomic layer deposition (ALD).

[0012] The Fig. 2A and Fig. Figure 2B schematically shows representative structures of the multidentate aromatic ligand 104 of the organometallic precursor 100 in Fig. 1. In one embodiment, as in Fig. As shown in Figure 2A, the multidentate aromatic ligand 104 comprises a conjugation structure 1040, a pyrrole-like nitrogen 1044, and a pyridine-like nitrogen 1042, the pyrrole-like nitrogen 1044 and the pyridine-like nitrogen 1042 being part of the aromatic ring of the conjugation structure 1040. The conjugation structure 1040 can include carbon (C), phosphorus (P), oxygen (O), sulfur (S), selenium (Se), or boron (B) atoms, which have overlapping p-orbitals and delocalization of π-electrons. In other words, the conjugation structure 1040 comprises a π-system (or a JI-conjugated system). The pyridine-like nitrogen 1042, as the name suggests, is bound or arranged similarly to the nitrogen in a pyridine molecule. The pyridine-like nitrogen 1042 has a lone pair of electrons that is part of the π-system of the conjugation structure.The pyrrole-like nitrogen 1044, as the name suggests, is bound or arranged similarly to the nitrogen in a pyrrole molecule. Pyrrole-like nitrogen 1044 also possesses a lone pair of electrons. Unlike the lone pair of electrons in pyridine-like nitrogen 1042, the lone pair of electrons in pyrrole-like nitrogen 1044 is not part of the π-system of the conjugation structure. In another, in . Fig. In the embodiment shown in Figure 2B, the multidentate aromatic ligand 104 comprises a conjugation structure 1040, a linked conjugation structure 1040', a pyridine-like nitrogen 1042 bound to the conjugation structure 1040, and a pyrrole-like nitrogen 1044 bound to the linked conjugation structure 1040'. Similar to the embodiment shown in Figure 2B, the conjugation structure 1040 is a multidentate aromatic ligand 1044. Fig. In the embodiment shown in Figure 2A, the conjugation structure 1040 and the linked conjugation structure 1040' can comprise carbon (C) atoms, phosphorus (P) atoms, oxygen (O) atoms, sulfur (S) atoms, selenium (Se) atoms, or boron (B) atoms exhibiting overlapping p-orbitals and delocalization of π-electrons. In other words, each of the conjugation structure 1040 and the linked conjugation structure 1040' comprises a π-system (or a π-conjugated system). In the embodiment shown in Fig. In the embodiment shown in Figure 2B, the pyridine-like nitrogen 1042 has a lone pair of electrons that is part of the π-system of the conjugation structure 1040. The lone pair of electrons of the pyrrole-like nitrogen 1044 is neither part of the π-system of the linked conjugation structure 1040' nor of the π-system of the conjugation structure 1040. For the sake of simplicity, the multidentate aromatic ligand 104 of the present disclosure can be considered to comprise a conjugation structure 1040, a pyrrole-like nitrogen 1044, and a pyridine-like nitrogen 1042. If the multidentate aromatic ligand 104 comprises more than one conjugation structure, the description of one conjugation structure generally also applies to the other conjugation structure.

[0013] Conjugation structure 1040 can comprise a 5-membered heterocyclic ring, a 6-membered heterocyclic ring, or a combination thereof. In some embodiments, conjugation structure 1040 can comprise two or more 5-membered heterocyclic rings linked or fused together, two or more 6-membered heterocyclic rings linked or fused together, at least one 5-membered heterocyclic ring, and at least one 6-membered heterocyclic ring linked or fused together. Since conjugation structure 1040 comprises a π-system and a ring-containing structure, it includes unsaturated ring(s) and can also be referred to as aromatic structure 1040.

[0014] Each of the pyrrole-like nitrogens 1044 and the pyridine-like nitrogens 1042 can donate an electron pair. For this reason, each of them can provide a denticity. Since the multidentate aromatic ligand 104 comprises at least one pyrrole-like nitrogen 1044 and one pyridine-like nitrogen 1042, the multidentate aromatic ligand 104 is capable of providing more than one denticity and is therefore "multidentate." The multidentate aromatic ligand 104 can comprise between two and four denticities. In some embodiments, the multidentate aromatic ligand 104 is coordinated to the metal ion 102 via the pyridine-like nitrogen 1042, and the pyrrole-like nitrogen 1044 remains uncoordinated. As described below, EUV irradiation can activate the pyrrole-like nitrogen 1044 to coordinate to a different metal ion.When this occurs, the pyrrole-like nitrogen 1044 and the pyridine-like nitrogen 1042 of a multidentate aromatic ligand 104 coordinate to two metal ions 102, thereby bridging them. In this respect, the multidentate aromatic ligand 104 acts as a bridging ligand, forming a bridge upon irradiation with EUV radiation.

[0015] Although not explicitly shown in the figures, in some alternative embodiments at least one of the pyrrole-like nitrogens 1044 and the pyridine-like nitrogen 1042 can be replaced by a thiophene-like sulfur (S), selenophene-like selenium (Se), thiazole-like sulfur (S), selenazole-like selenium (Se), furan-like oxygen (O), oxazole-like oxygen (O), diazaborinin-like boron (B), bis(methylamini)bore-like boron (B), a triphosphole-like phosphorus (P), or other electron-donating forms of sulfur (S), selenium (Se), oxygen (O), boron (B), or phosphorus (P). Some of these replacements may feature a lone pair of electrons that is part of the π-system of the multidentate aromatic ligand 104. Some of them may include a lone pair of electrons that is not part of the π-system of the multidentate aromatic ligand 104.Some of them can possess a lone pair of electrons in the π-system and another lone pair of electrons located outside the π-system. Like the pyrrole-like nitrogen 1044 or the pyridine-like nitrogen 1042, the substitute sulfur (S), selenium (Se), phosphorus (P), boron (B), or oxygen (O) can also provide denticity and serve as part of the bridging ligand—the multidentate aromatic ligand 104. Although the present disclosure describes the pyrrole-like nitrogen 1044 and the pyridine-like nitrogen 1042 in more detail, similar mechanisms and applications may also apply to these alternative embodiments.

[0016] Fig. Figure 3 shows exemplary single-ring multidentate aromatic ligands 104. These exemplary single-ring multidentate aromatic ligands 104 generally correspond to those in Fig. 2A, embodiment in which there is only one conjugation structure 1040. These examples include pyrazole, imidazole, 1,2,4-triazole, 1,2,3-triazole, and tetrazole. As in Fig. As can be seen in Figure 3, each of these examples comprises a conjugation structure that includes a π-system, at least one pyrrole-like nitrogen, and at least one pyridine-like nitrogen. Although not explicitly shown, the following can be observed in Figure 3: Fig. The examples shown in 3 also extend to their derivatives, in which the hydrogen atoms are substituted with an alkyl group, an alkenyl group or a fluorine.

[0017] In Fig. Figure 4 shows exemplary multi-ring, multidentate aromatic ligands 104. These exemplary multidentate aromatic ligands 104 generally correspond to those shown in Figure 4. Fig. 2B, the embodiment shown, in which a conjugation structure 1040 and a linked conjugation structure 1040' are present. These examples include indazole, benzimidazole, 7-azaindole, 4-azaindole, pyrrolylpyridine, or purine. As shown in Fig. As can be seen in Figure 4, each of these examples comprises a conjugation structure that includes a π-system, at least one pyrrole-like nitrogen, and at least one pyridine-like nitrogen. Although not explicitly shown, the following can be observed in Figure 4: Fig. The examples shown in 4 also extend to their derivatives, in which the hydrogen atoms are substituted with an alkyl group, an alkenyl group or a fluorine.

[0018] Fig. Figure 106 shows examples of EUV-cleavable ligands. These examples include an alkenyl group or a carboxylate group. The groups R1, R2, and R3 in the alkenyl group can include hydrogen, fluorine, or an alkyl group. The groups R4 in the carboxylate group can include hydrogen, fluorine, or an alkyl group. The groups R1, R2, R3, and R4 can be the same or different. The alkyl groups in these exemplary EUV-cleavable ligands can be linear, branched, or cyclic and can include 1 to 6 carbon atoms. Both the alkenyl group and the carboxylate group contain a double bond that can be cleaved by EUV radiation, which gives these exemplary EUV-cleavable ligands their EUV-cleavable property.

[0019] Fig. Figure 6 shows the organometallic precursor 100 undergoing a reduction reaction according to various aspects of the present disclosure. For easier illustration, in Fig. Figure 6 shows only four organometallic precursors 100. Upon incidence of EUV radiation, at least one EUV-cleavable ligand (L) 106 is cleaved from each of the four organometallic precursors 100 to provide coordination sites for metal ions 102. Furthermore, the EUV radiation can cleave the nitrogen-hydrogen bond (NH) of the pyrrole-like nitrogen, causing the pyrrole-like nitrogen to lose a hydrogen atom and activating the nitrogen site (N-site) of the pyrrole-like nitrogen. The EUV-cleavable ligand (L) 106 and the hydrogen atom can combine to form a leaving group. The activated N-site of the pyrrole-like nitrogen of a multidentate aromatic ligand 104 can coordinate to a coordination site of a metal ion 102 that was left free by the departing EUV-cleavable ligand 106.The reduction of the EUV-cleavable ligand (L) 106 and the hydrogen leads to the crosslinking of the four organometallic precursors 100. Some of the multidentate aromatic ligands 104 extend between two metal ions 102 and act as bridging ligands.

[0020] The reduction reaction in Fig. This will be further illustrated by an example. In the Fig. In the example shown in Figure 7, the organometallic precursor 100 comprises a metal ion 102 coordinated to an EUV-cleavable ligand (L) 106, and imidazole as an example of the multidentate aromatic ligand 104. Specifically, the imidazole is coordinated to the metal ion 102 via the pyrrole-like nitrogen 1044, while the pyridine-like nitrogen 1042 remains uncoordinated. Upon incidence of EUV radiation 150, the EUV-cleavable ligand (L) 106 is cleaved from the metal ion 102 by the radicals generated by the EUV radiation 150, leaving a free coordination site of the metal ion 102. The EUV radiation 150 also cleaves the bond between the hydrogen and the pyrrole-like nitrogen 1044, thereby activating the pyrrole-like nitrogen 1044. The EUV fissionable ligand (L) 106 and the released hydrogen can form a leaving group (LH) and the activated pyrrole-like nitrogen 1044 can coordinate to the free coordination site.As a result, the multidentate aromatic ligand 104 bridges two metal ions 102 with its two dentin sites.

[0021] In general, a positive photoresist (or positive-tone photoresist) is a type of photoresist in which the exposed portion of the photoresist becomes soluble in the photoresist developer. The unexposed portion of the photoresist remains insoluble in the photoresist developer. A negative photoresist (or negative-tone photoresist) is a type of photoresist in which the exposed portion of the photoresist becomes insoluble in the photoresist developer. The unexposed portion of the photoresist is dissolved by the photoresist developer. Because EUV irradiation forms cross-links that decrease the solubility of the metal-organic precursor 100 in a developer, the metal-organic precursor 100 can be an active component of a negative photoresist for EUV lithography. Fig. Figure 8 shows a flowchart of a process 200 for structuring a material layer on a workpiece using a negative photoresist, which includes the metal-organic precursor 100 described herein. Process 200 is merely an example and is not intended to limit the present disclosure to what is explicitly described in process 200. Additional steps may be provided before, during, and after process 200, and some described steps may be replaced, eliminated, or rearranged for additional embodiments of the process. For the sake of simplicity, not all steps are described in detail here. Process 200 is subsequently referred to in conjunction with the Fig. Figures 9-15 describe fragmentary cross-sectional views of a workpiece 300 at various stages of manufacture according to the embodiments of the method 200. Furthermore, in this application, identical reference numbers denote identical features unless otherwise specified.

[0022] Referring to Fig. 8 and Fig. In section 9, the method 200 comprises a block 202 in which a workpiece 300 is provided. The workpiece 300 comprises a substrate 302 and a layer of material 304 arranged above the substrate 302. It should be noted that the substrate 302 is in Fig. 9 is shown in dashed lines and in the Fig. Figures 10-15 are omitted for simplicity. Substrate 302 can comprise an elemental (single-element) semiconductor, such as silicon (Si) and / or germanium (Ge); a compound semiconductor, such as silicon carbide (SiC), gallium arsenide (GaAs), gallium phosphide (GaP), indium phosphide (InP), indium arsenide (InAs), and / or indium antimonide (InSb); a semiconductor alloy, such as silicon-germanium (SiGe), gallium arsenic phosphide (GaAsP), aluminum indium arsenide (AlInAs), aluminum gallium arsenide (AlGaAs), gallium indium arsenide (GalnAs), gallium indium phosphide (GaInP), and / or gallium indium arsenic phosphide (GalnAsP); a non-semiconductor material, such as soda-lime glass, fused silica, quartz glass and / or calcium fluoride (CaF2); and / or combinations thereof.In some other embodiments, the substrate 302 can be a single-layer material with a uniform composition; alternatively, the substrate 302 can comprise multiple layers of material with similar or different compositions suitable for fabricating IC components. In one example, the substrate 302 can be a silicon-on-insulator (SOI) substrate with a semiconductor silicon layer formed on a silicon oxide layer. The substrate 302 can include various circuit features formed thereon, such as field-effect transistors (FETs), metal-oxide-semiconductor field-effect transistors (MOSFETs), CMOS transistors, high-voltage transistors, high-frequency transistors, bipolar transistors, diodes, resistors, capacitors, inductors, varactors, other suitable components, and / or combinations thereof.

[0023] The material layer 304 above the substrate 302 constitutes a top layer onto which a photoresist layer 306 (described below) is deposited. That is to say, in some cases, the material layer 304, together with one or more underlying layers, is to be structured. In some embodiments, the material layer 304 can be a dielectric layer serving as a hard mask layer, a bottom antireflection layer (BARC), or an insulating layer. In these embodiments, the material layer 304 can comprise silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, silicon oxycarbonitride, a metal oxide, silicon carbide, or silicon oxycarbide.Examples of metal oxides include high-k dielectric materials such as titanium oxide (TiO2), hafnium zirconium oxide (HfZrO), tantalum oxide (Ta2O5), hafnium silicon oxide (HfSiO4), zirconium oxide (ZrO2), zirconium silicon oxide (ZrSiO2), lanthanum oxide (La2O3), aluminum oxide (Al2O3), zirconium oxide (ZrO), yttrium oxide (Y2O3), SrTiO3 (STO), BaTiO3 (BTO), BaZrO, hafnium lanthanum oxide (HfLaO), lanthanum silicon oxide (LaSiO), aluminum silicon oxide (AlSiO), hafnium tantalum oxide (HfTaO), hafnium titanium oxide (HfTiO), or (Ba,Sr)TiO3 (BST). In some other embodiments, the material layer 304 can comprise a semiconductor material such as silicon (Si), germanium (Ge), gallium arsenide (GaAs), gallium phosphide (GaP), gallium nitride (GaN), or silicon germanium (SiGe). In still other embodiments, the material layer 304 can comprise a polymer layer, such as a polyimide layer or a polymer BARC layer.In other embodiments, the material layer 304 can comprise a conductive material, such as titanium nitride (TiN), titanium aluminum (TiAl), titanium aluminum nitride (TiAlN), tantalum nitride (TaN), tantalum aluminium (TaAl), tantalum aluminium nitride (TaAlN), tantalum aluminum (TaAl), tantalum aluminum carbide (TaAlC), tantalum carbonitride (TaCN), aluminum (Al), tungsten (W), nickel (Ni), titanium (Ti), ruthenium (Ru), cobalt (Co), platinum (Pt), tantalum carbide (TaC), tantalum silicon nitride (TaSiN), or copper (Cu). If the material layer 304 includes surface-functional groups, such as... B. a hydroxyl group or an amine group, the material layer 304 can form good adhesion with the subsequently deposited photoresist layer 306, since the photoresist layer 306 comprises the metal-organic precursor 100.

[0024] In some embodiments where the material layer 304 can catalyze premature crosslinking of the photoresist layer 306 (described below), a very thin silicon oxide layer or a very thin polymer layer can be deposited in block 202 on the material layer 304 as a protective cap (or cap layer) before the photoresist layer is deposited.

[0025] With reference to the Fig. 8 and Fig. In section 10, the process 200 comprises a block 204 in which a photoresist layer 306 is deposited onto the material layer 304. The photoresist layer 306 comprises the above-described organometallic precursor 100 and may include further additives or surfactants. The photoresist layer 306 may be a negative photoresist layer. In some embodiments, the photoresist layer 306 may be deposited by spin deposition, chemical vapor deposition (CVD), or atomic layer deposition (ALD). If the photoresist layer 306 is deposited by spin deposition, the organometallic precursor 100 may be dissolved or dispersed in a dispersion or solution together with additives and surfactants and then deposited onto the material layer 304.Since the metal-organic precursor 100 in the photoresist layer 306 comprises at least one unsaturated coordination site 1046 (typically about 1 to 2 unsaturated coordination sites) that can be coordinated to a functional group or a dangling bond of the material layer 304, the photoresist layer 306 can adhere well to the material layer 304 without the need for surface treatment or modification of the material layer 304, such as HDMS pretreatment. As an example, see... Fig. 16, that the metal-organic precursor 100 in the photoresist layer 306 can be coordinated to a hydroxyl group of the material layer 304.

[0026] When the photoresist layer 306 is deposited by ALD or CVD, gas precursors for the metal-organic precursor 100 can be directed onto the material layer 304, where the gas precursors react with each other and with the material layer 304 to form the photoresist layer 306. In some cases, the gas precursors can comprise a first and a second gas precursor. The first gas precursor can comprise a halogenated EUV-cleavable ligand 106, such as an alkene halide. The second gas precursor can comprise the metal ion 102 coordinated to the multidentate aromatic ligands 104 and halides. The halogen components allow the gas precursors to exist in gaseous form. During the CVD or ALD process, the material layer 304 can be heated, and the halogen components can be removed when the first and second gas precursors come into contact with the heated material layer 304.In other words, if the photoresist layer 306 is deposited using ALD or CVD, the photoresist layer 306 can be formed by a chemical reaction involving a vapor-type metal-organic precursor (M. a X b V c , where V is a volatile group such as a halide or a halogen-containing group) and EUV-fibrillatable vapor-type ligands (L) are mixed to form the metal-organic precursor 100 (M a X b L c ) to form, and is then deposited on the surface of the material layer 304.

[0027] Referring to Fig. and Fig. The process 200 comprises a block 206 in which a pre-exposure treatment process 400 is performed. The pre-exposure treatment process 400 can also be referred to as a post-treatment process 400. The pre-exposure treatment process 400 facilitates the outgassing of unwanted species or removes excess moisture from the photoresist layer 306. The unwanted species may include byproducts or leaving groups from the CVD or ALD process if gaseous precursors are used to deposit the photoresist layer 306. Examples include halide-containing species. Depending on the properties of the species to be removed, the pre-exposure treatment process 400 may include a heating process, an infrared curing process, an ultraviolet (UV) curing process, or a visible light curing process.In some alternative embodiments where unwanted species are to be neutralized, the pre-exposure treatment process can include modifying the surface of the photoresist layer 306 with a reactive gas, such as silane (SiH4). If the pre-exposure treatment process 400 includes a heating process, the heating temperature can be between approximately 60°C and approximately 170°C.

[0028] With reference to the Fig. 8 and Fig. In section 12, the process 200 comprises a block 208 in which the photoresist layer 306 is exposed with an irradiation pattern. The exposure in block 208 can be carried out using a lithography system 500, which is described in Fig. Figure 12 is shown schematically. The lithography system 500 can also be generally referred to as a scanner capable of performing lithographic processes, including exposure with a suitable radiation source and in a specific exposure mode. In at least some of the present embodiments, the lithography system 500 comprises an extreme ultraviolet (EUV) lithography system designed to expose a photoresist layer, such as the photoresist layer 306, by EUV radiation. The lithography system 500 of Fig. The system comprises a variety of subsystems, including an EUV source 502, an illumination unit 504, a mask stage 506 configured to hold a mask 508, a projection optic 510, and a substrate stage 514 configured to hold a workpiece, such as the workpiece 300. A general description of the operation of the lithography system 500 can be given as follows: EUV radiation from the EUV source 502 is directed to the illumination unit 504 (which includes a set of reflection mirrors) and projected onto the reflection mask 508. A reflected mask image is directed to the projection optic 510, which focuses the EUV light and projects it onto the workpiece 300 to expose an EUV resist layer deposited thereon. Furthermore, in various examples, each subsystem of the lithography system 500 can be arranged in a high vacuum environment and thus operate in this environment, e.g.to reduce the atmospheric absorption of EUV light.

[0029] In the embodiments described here, the EUV source 502 can be used to generate the EUV radiation. In some embodiments, the EUV source 502 comprises a plasma source, such as a discharge-generated plasma (DPP) or a laser-generated plasma (LPP). In some examples, the EUV radiation can include radiation with a wavelength centered at approximately 13.5 nm. In some embodiments, the EUV source 502 also includes a collector that can be used to collect the EUV radiation generated by the plasma source and direct the EUV radiation onto imaging optics such as the illuminator 504. As described above, the EUV radiation is directed from the EUV source 502 onto the illuminator 504. In some embodiments, the illuminator 504 can include reflective optics, such as...a single mirror or a system of multiple mirrors to direct the radiation from the EUV source 502 onto the mask table 506 and, in particular, onto the mask 508 mounted on the mask table 506. In some embodiments, the illuminator 504 may, for example, include a zone plate to improve the focusing of the EUV radiation. In some embodiments, the illuminator 504 may be configured to shape the EUV radiation passing through it according to a specific pupil shape, and may, for example, include a dipole shape, a quadrupole shape, annular shape, a single-beam shape, a multiple-beam shape, and / or a combination thereof. In some embodiments, the illumination device 504 may be configured such that the mirrors (i.e., the mirrors of the illumination device 504) provide desired illumination for the mask 508.In one example, the mirrors of the illuminator 504 are configurable to reflect EUV radiation to different illumination positions. In some embodiments, a table upstream of the illuminator 504 may additionally include other configurable mirrors that can be used to direct the EUV radiation to different illumination positions within the mirrors of the illuminator 504. In some embodiments, the illuminator 504 is configured to provide on-axis (ONI) illumination to the mask 508. In some embodiments, the illuminator 504 is configured to provide off-axis (OAI) illumination to the mask 508. It should be noted that the optics used in the EUV lithography system 500, in particular those used for the illuminator 504 and the projection optics 510, may include mirrors with multilayer thin-film coatings known as Bragg reflectors.For example, such a multilayer thin-film coating can include alternating layers of Mo and Si, which provides high reflectivity at EUV wavelengths (e.g., about 13 nm).

[0030] As described above, the lithography system 500 also includes the mask stage 506, which is configured to hold the mask 508. Since the lithography system 500 can be located in and operated in a high-vacuum environment, the mask stage 506 can include an electrostatic clamping device (E-Chuck) for securing the mask 508. Like the optics of the EUV lithography system 500, the mask 508 is also reflective. As in the example of Fig. As shown in Figure 12, the radiation is reflected by the mask 508 and directed onto the projection optics 510, which collects the EUV radiation reflected by the mask 508. The EUV radiation collected by the projection optics 510 (reflected by the mask 508) carries, by way of example, an image of the pattern defined by the mask 508. In various embodiments, the projection optics 510 image the pattern of the mask 508 onto the workpiece 300, which is mounted on the substrate table 514 of the lithography system 500. In particular, in various embodiments, the projection optics 510 focuses the collected EUV light and projects it onto the workpiece 300 to expose the photoresist layer 306 on the workpiece 300. As described above, the projection optics 510 can include a reflective optic, such as that used in EUV lithography systems like the lithography system 500.In some embodiments, the illuminator 504 and the projection optics 510 are jointly referred to as the optical module of the lithography system 500.

[0031] In some embodiments, the lithography system 500 also includes a pupil phase modulator 512 to modulate the optical phase of the EUV radiation emitted from the mask 508, so that the light has a phase distribution along a projection pupil plane. In some embodiments, the pupil phase modulator 512 includes a mechanism for tuning the reflection mirrors of the projection optics 510 for phase modulation. For example, in some embodiments, the mirrors of the projection optics 510 are configurable to reflect the EUV light through the pupil phase modulator 512, thereby modulating the phase of the light through the projection optics 510. In some embodiments, the pupil phase modulator 512 uses a pupil filter arranged in the projection pupil plane. The pupil filter can, for example, be aThey are used to filter out specific spatial frequency components of the EUV radiation reflected by the mask 508. In some embodiments, the pupil filter can serve as a phase pupil filter, modulating the phase distribution of the light directed by the projection optics 510.

[0032] As in Fig. As shown in Figure 12, when using the lithography system 500, an exposed section 310 of the photoresist layer 306 is exposed with EUV radiation, while an unexposed section 308 remains unexposed. The metal-organic precursors 100 in the exposed section 310 of the photoresist layer 306 are crosslinked. In particular, with reference to Fig. 1 and Fig. 2. The EUV radiation of the lithography system 500 generates radicals. The radicals cleave the EUV-cleavable ligands 106 from the metal ion 102 and the hydrogen from the pyrrole-like nitrogen 1044. The pyrrole-like nitrogen 1044 is activated and coordinates to another metal ion that has an uncoordinated site. The multidentate aromatic ligands 104 serve as bridging ligands for the formation of cross-links. The same cross-linking does not occur in the unexposed section 308 with EUV-generated radicals.

[0033] Referring to Fig. 8 and Fig. In section 13, the method 200 comprises a block 210 in which a post-exposure heating process 600 is carried out. In some embodiments, a heating temperature or heating temperature profile of the post-exposure heating process 600 is selected such that the removal of the discharge group generated in block 208 during the EUV exposure process is ensured. This discharge group corresponds to the discharge group LH described above. The heating temperature of the post-exposure heating process 600 can be between approximately 50°C and approximately 150°C.

[0034] Referring to Fig. 8 and Fig. In section 14, the method 200 comprises a block 212 in which the exposed photoresist layer 306 is developed to form a structured photoresist layer 312. In block 212, a developer solution is used to remove the unexposed section 308, which was not crosslinked in block 212. The developer solution is selected to selectively dissolve and remove the unexposed (uncrosslinked) section 308 while leaving the exposed (crosslinked) section 310 of the photoresist layer 306 substantially intact. Suitable developer solutions may include solvents such as n-butyl acetate, ethanol, hexane, benzene, toluene, water, isopropyl alcohol (IPA), or 2-heptanone. In some embodiments, block 212 may also include one or more defoaming or rinsing operations to remove any remaining photoresist layer 306 or deposits. At the end of the processes in block 212, the structured photoresist layer 312 is formed.Due to the removal of the unexposed section 308, the structured photoresist layer 312 includes an aperture 314, and the material layer 304 is exposed in the aperture 314.

[0035] Referring to Fig. 8 and Fig. In Figure 15, the method 200 comprises a block 214 in which the material layer 304 is etched using the structured photoresist layer 314 as an etching mask. In some embodiments, the material layer 304 is etched using a dry etching process 700, such as a reactive ion etching (RIE) process, with the structured photoresist layer 312 as an etching mask. In some examples, the dry etching process 700 can be carried out using an etching gas that is a fluorine-containing etching gas (e.g., NF3, CF4, SF6, CH2F2, CHF3, and / or C2F6), an oxygen-containing gas (e.g., O2), a chlorine-containing gas (e.g., Cl2, CHCl3, CCl4, SiCl4, and / or BCl3), a nitrogen-containing gas (e.g., N2), a bromine-containing gas (e.g., HBr and / or CHBr3), an iodine-containing gas, other suitable gases, and / or plasmas, or combinations thereof. In some embodiments described in Fig.As shown in Figure 15, the dry etching process 700 forms a depression 316 in the material layer 304. While the depression 316 is shown in such a way that it does not extend through the material layer 304, in alternative embodiments it may extend through the material layer 304.

[0036] Although not intended as a limitation, one or more embodiments of the present disclosure offer many advantages for a semiconductor device and a fabrication method therefor. For example, the present disclosure provides a metal-organic precursor in a negative-tone photoresist. The metal-organic precursor of the present disclosure comprises a metal ion coordinated to a variety of multidentate aromatic ligands and a variety of EUV cleavable ligands. The multidentate aromatic ligand comprises a conjugation structure, a pyrrole-like nitrogen, and a pyridine-like nitrogen. The EUV cleavable ligand includes an alkenyl group or a carboxylate group. Each of the multidentate aromatic ligands is coordinated to the metal ion via the pyrrole-like nitrogen.When the organometallic precursor is irradiated with EUV radiation, the pyrrole-like nitrogen atoms of the multidentate aromatic ligands are activated, and the EUV-cleavable ligands are cleaved from the metal ion. The activated pyrrole-like nitrogen can coordinate to another metal ion at coordinate sites freed by the cleavage of the EUV-cleavable ligands. The metal ions have a high atomic absorption cross-section, so available coordination sites can be used to bind to various functional groups on the surface. The mode and degree of crosslinking can be precisely controlled by adjusting the stoichiometry ratio of the EUV-cleavable ligands to the multidentate aromatic ligands.

[0037] In one exemplary aspect, the present disclosure relates to a metal-organic precursor that is provided. The metal-organic precursor comprises a chemical formula MaXbLc, where M is a metal, X is a multidentate aromatic ligand comprising a pyrrole-like nitrogen and a pyridine-like nitrogen, L is a ligand cleavable in the extreme ultraviolet (EUV), a is between 1 and 2, b is equal to or greater than 1, and c is equal to or greater than 1.

[0038] In some embodiments, the sum of b and c is less than 5. In some embodiments, the multidentate aromatic ligand comprises at least one π-conjugated system, the pyrrole-like nitrogen comprises a lone pair of electrons that is part of one of the at least one π-conjugated system, and the pyridine-like nitrogen comprises a lone pair of electrons that is not part of one of the at least one π-conjugated system. In some embodiments, the metal has a high atomic absorption cross-section. In some embodiments, the metal is selected from a group consisting of tin (Sn), bismuth (Bi), antimony (Sb), indium (In), and tellurium (Te). In some embodiments, the multidentate aromatic ligand comprises a five-membered aromatic ring. In some cases, the multidentate aromatic ligand further comprises a six-membered aromatic ring that is fused or linked to the five-membered aromatic ring.In some cases, the multidentate aromatic ligand comprises pyrazole, imidazole, 1,2,4-triazole, 1,2,3-triazole, tetrazole, indazole, benzimidazole, 7-azaindole, 4-azaindole, pyrrolylpyridine, or purine. In some embodiments, the EUV-cleavable ligand comprises an alkenyl group or a carboxylate group.

[0039] In another exemplary aspect, the present disclosure relates to an extreme ultraviolet (EUV) photoresist precursor. The extreme ultraviolet (EUV) photoresist precursor comprises a metal ion, an EUV-cleavable ligand coordinated to the metal ion, and a multidentate ligand coordinated to the metal ion. The multidentate ligand comprises at least one π-conjugated system, a first nitrogen containing a first lone pair of electrons, and a second nitrogen containing a second lone pair of electrons. The first lone pair of electrons is part of one of the at least one π-conjugated system, and the second lone pair of electrons is not part of one of the at least one π-conjugated system.

[0040] In some embodiments, the first nitrogen is a pyrrole-like nitrogen and the second nitrogen is a pyridine-like nitrogen. In some embodiments, the metal ion has a high atomic absorption cross-section. In some cases, the metal ion is selected from a group consisting of tin (Sn), bismuth (Bi), antimony (Sb), indium (In), and tellurium (Te). In some embodiments, the polydentate ligand comprises a five-membered aromatic ring. In some cases, the EUV-cleavable ligand comprises an alkenyl group or a carboxylate group.

[0041] In another exemplary aspect, the present disclosure relates to a process. The process comprises the deposition of a photoresist layer directly onto a material layer, wherein the photoresist layer comprises a precursor comprising a metal ion, an extreme ultraviolet (EUV) cleavable ligand coordinated to the metal ion, and an aromatic ligand coordinated to the metal ion, the aromatic ligand comprising a pyrrole-like nitrogen and a pyridine-like nitrogen. The process further comprises irradiating a portion of the photoresist layer with EUV radiation to cleave the EUV-cleavable ligand from a coordination site of the metal ion, to activate the pyrrole-like nitrogen, and to coordinate the activated pyrrole-like nitrogen to the coordination site.

[0042] In some embodiments, the process may further include heating the photoresist layer after exposure to crosslink that portion of the photoresist layer. In some embodiments, the material layer comprises a dielectric layer, a conductive layer, a polymer layer, or a semiconductor layer. In some embodiments, the deposition of the photoresist layer includes the use of spin coating, chemical vapor deposition (CVD), or atomic layer deposition (ALD). In some embodiments, the deposition of the photoresist layer includes the use of gaseous precursors.

[0043] The foregoing outlines features of several embodiments to help the person skilled in the art better understand the aspects of the present disclosure. The person skilled in the art should be aware that they can readily use the present disclosure as a basis for developing or modifying other methods and structures to achieve the same purposes and / or the same advantages as the embodiments presented herein. The person skilled in the art should also recognize that such equivalent designs do not deviate from the spirit and scope of the present disclosure, and that they can make various changes, substitutions, and modifications therein without deviating from the spirit and scope of the present disclosure. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 63085364

[0001]

Claims

[1] Organometallic precursor having a chemical formula M a X b L c includes where M is a metal where X is a multidentate aromatic ligand comprising a pyrrole-like nitrogen and a pyridine-like nitrogen, where L is a ligand that can be split in the extreme ultraviolet (EUV) range, where a lies between 1 and 2, where b is equal to or greater than 1, and where c is equal to or greater than 1. [2] Organometallic precursor according to claim 1, wherein the sum of b and c is less than 5. [3] Organometallic precursor according to claim 1 or 2, wherein the multidentate aromatic ligand comprises at least one π-conjugated system, wherein the pyrrole-like nitrogen comprises a lone pair of electrons that is part of at least one π-conjugated system, wherein the pyridine-like nitrogen comprises a lone pair of electrons that is not part of one of the at least one π-conjugated systems. [4] Organometallic precursor according to any of the preceding claims, wherein the metal has a high atomic absorption cross-section. [5] Organometallic precursor according to any of the preceding claims, wherein the metal is selected from the group consisting of tin (Sn), bismuth (Bi), antimony (Sb), indium (In) and tellurium (Te). [6] Organometallic precursor according to any of the preceding claims, wherein the multidentate aromatic ligand comprises a five-membered aromatic ring. [7] Organometallic precursor according to claim 6, wherein the multidentate aromatic ligand further comprises a six-membered aromatic ring which is fused or connected to the five-membered aromatic ring. [8] Organometallic precursor according to any of the preceding claims, wherein the multidentate aromatic ligand comprises pyrazole, imidazole, 1,2,4-triazole, 1,2,3-triazole, tetrazole, indazole, benzimidazole, 7-azaindole, 4-azaindole, pyrrolylpyridine or purine. [9] Organometallic precursor according to any of the preceding claims, wherein the EUV-cleavable ligand comprises an alkenyl group or a carboxylate group. [10] Extreme ultraviolet (EUV) photoresist precursor, comprising the following: a metal ion; an EUV fissionable ligand coordinated to the metal ion; and a multidentate ligand coordinated to the metal ion, wherein the multidentate ligand comprises: at least one π-conjugated system, a first nitrogen atom, which includes a first lone pair of electrons, and a second nitrogen comprising a second lone pair of electrons, wherein the first lone pair of electrons is part of one of the at least one π-conjugated system and the second lone pair of electrons is not part of one of the at least one π-conjugated system. [11] EUV photoresist precursor according to claim 10, wherein the first nitrogen is a pyrrole-like nitrogen and the second nitrogen is a pyridine-like nitrogen. [12] EUV photoresist precursor according to claim 10 or 11, wherein the metal ion has a high atomic absorption cross-section. [13] EUV photoresist precursor according to any one of claims 10 to 12, wherein the metal ion is selected from a group consisting of tin (Sn) ion, bismuth (Bi) ion, antimony (Sb) ion, indium (In) ion and tellurium (Te) ion. [14] EUV photoresist precursor according to any one of claims 10 to 13, wherein the multidentate ligand comprises a five-membered aromatic ring. [15] EUV photoresist precursor according to any one of claims 10 to 13, wherein the EUV cleavable ligand comprises an alkenyl group or a carboxylate group. [16] Method comprising the following: Deposition of a photoresist layer directly onto a material layer, wherein the photoresist layer comprises a precursor having the following features: a metal ion, an extremely ultraviolet (EUV) fissionable ligand coordinated to the metal ion, and an aromatic ligand coordinated to the metal ion, wherein the aromatic ligand comprises a pyrrole-like nitrogen and a pyridine-like nitrogen nitrogen includes; and Exposing part of the photoresist layer with EUV radiation to: to cleave the EUV-fissile ligand from a coordination site of the metal ion, to activate the pyrrole-like nitrogen, and to coordinate the activated pyrrole-like nitrogen to the coordination site. [17] The method of claim 16, further comprising: After exposure, the photoresist layer is heated to crosslink that part of the photoresist layer. [18] Method according to claim 16 or 17, wherein the material layer comprises a dielectric layer, a conductive layer, a polymer layer or a semiconductor layer. [19] Method according to any one of claims 16 to 18, wherein the deposition of the photoresist layer comprises the use of spin coating, chemical vapor deposition (CVD) or atomic layer deposition (ALD). [20] Method according to any one of claims 16 to 19, wherein the deposition of the photoresist layer comprises the use of gaseous precursors.