Method for fabricating an EUV mask including an absorber layer

Abstract

An embodiment of the present invention provides a method of forming an extreme ultraviolet (EUV) mask. The method includes sublimating a radiation sensitive material onto a surface of an EUV blank substrate, exposing the radiation sensitive material to ionizing radiation to form an EUV mask pattern, and removing a portion of the radiation sensitive material from the surface of the EUV blank substrate, where the portion of the radiation sensitive material is not exposed to the ionizing radiation. Additionally, a fabricated EUV mask, and associated radiation sensitive material, are also provided.

Description

[Technical field]

[0001] This invention relates to the manufacture of semiconductor integrated circuits. More particularly, this invention relates to masks used in extreme ultraviolet (EUV) lithography, the fabrication of masks, and materials used in the fabrication of masks. [Background technology]

[0002] As integrated circuit devices shrink in size, various single or double patterning lithography processes have come into widespread use, for example, lithography processes based on deep ultraviolet (DUV) radiation wavelengths of 193 nanometers (nm). Recently, extreme ultraviolet (EUV) lithography processes based on radiation with a wavelength of 13.5 nm have been developed and are expected to facilitate and even enhance precise patterning of semiconductor device features at, for example, the 10 nm production node and below.

[0003] In EUV lithography, a dedicated EUV mask that contains a mask absorber or absorber layer is typically used. For high numerical aperture (NA) EUV lithography, the mask absorber layer needs to be ultra-thin to address and avoid the shadowing effect. There are several metal elements that are suitable for fabricating thin metal absorbers. However, etching these metal elements is known to be difficult due to the lack of volatile metal by-products. Fabricating thin metal absorbers from these metal elements generally requires physical etching processes such as sputtering techniques, which complicates the overall manufacturing process and increases the costs associated with fabrication. Summary of the Invention

[0004] As the inventors have recognized, what is needed to create metal nanostructures that can be used as mask absorbers is the creation, formation, or discovery of new materials, or a combination thereof, as well as methods for processing these materials. In processing these new materials, embodiments of the present invention avoid the transfer of a typical printed resist pattern or image onto an EUV blank substrate by using an ionizing beam, such as electron beam (e-beam) lithography, to create a mask absorber that is formed directly on top of the EUV blank substrate.

[0005] An embodiment of the present invention provides a method of forming an extreme ultraviolet (EUV) mask. The method includes sublimating a layer of radiation sensitive material onto a surface of an EUV blank substrate, exposing the layer of radiation sensitive material to ionizing radiation to form an EUV mask pattern, and removing a portion of the layer of radiation sensitive material from the surface of the EUV blank substrate, where the portion of the layer of radiation sensitive material is not exposed to the ionizing radiation. In one aspect, the EUV blank substrate includes an EUV reflector multilayer formed on the EUV mask substrate. One embodiment further includes densifying the portion of the radiation sensitive material exposed to the ionizing radiation.

[0006] According to one embodiment, the radiation sensitive material comprises one or more of the following EUV absorbing compounds: nickel acetate; nickel formate; nickel acetylacetonate; polynuclear nickel complexes; platinum and palladium complexes with azides, carbonates, oxalates, and acetylacetonates; polynuclear palladium and platinum complexes; silver and gold complexes with unsaturated hydrocarbons and phosphines; polynuclear silver and gold complexes; chromium complexes with arenes, thiocyanates, and bipyridines; and polynuclear chromium complexes.

[0007] In one embodiment, the radiation sensitive material includes organic ligands and exposing the radiation sensitive material to ionizing radiation includes removing the organic ligands from the portions of the radiation sensitive material that are exposed to the ionizing radiation, hi another embodiment, the radiation sensitive material includes one or more EUV absorbing metal elements of silver (Ag), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), and chromium (Cr).

[0008] In one embodiment, removing a portion of the layer of radiation sensitive material includes sublimating the portion of the layer of radiation sensitive material away from the EUV blank substrate.

[0009] An embodiment of the present invention also provides an extreme ultraviolet (EUV) mask blank, the EUV mask blank including an EUV mask substrate, an EUV reflector multilayer on the EUV mask substrate, and an imaging layer on the EUV reflector multilayer, the imaging layer being a layer of radiation-sensitive material including one or more EUV-absorbing metallic elements, such as silver (Ag), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), chromium (Cr), etc., that is radiation-patternable.

[0010] In one embodiment, the imaging layer of the EUV mask blank comprises one or more organic ligands selected from the group including acetate, formate, acetylacetonate, azide, carbonate, oxalate, unsaturated hydrocarbon, phosphine, arene, thiocyanate, and bipyridine.

[0011] In another embodiment, the imaging layer of the EUV mask blank comprises one or more of the following EUV absorbing compounds: nickel acetate; nickel formate; nickel acetylacetonate; polynuclear nickel complexes; platinum and palladium complexes with azides, carbonates, oxalates, and acetylacetonates; polynuclear palladium and platinum complexes; silver and gold complexes with unsaturated hydrocarbons and phosphines; polynuclear silver and gold complexes; chromium complexes with arenes, thiocyanates and bipyridines; and polynuclear chromium complexes with arenes, thiocyanates and bipyridines.

[0012] In one embodiment, the EUV reflector multilayer of the EUV mask blank includes multiple alternating transition metal molybdenum (Mo) layers and multiple silicon (Si) layers.

[0013] In another embodiment, the EUV mask substrate of the EUV mask blank comprises a low thermal expansion material such as fused silica, quartz, or silicon carbide.

[0014] An embodiment of the present invention further provides a radiation-patternable material, comprising one or more extreme ultraviolet (EUV) absorbing metal elements and an organic ligand selected from the group comprising acetate, formate, acetylacetonate, azide, carbonate, oxalate, unsaturated hydrocarbon, phosphine, arene, thiocyanate, and bipyridine, wherein the radiation-patternable material is adapted to be deposited on a surface of an EUV blank substrate via a sublimation process to form an ultrathin film.

[0015] In one embodiment, the one or more EUV absorbing metal elements include one or more of silver (Ag), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), and chromium (Cr).

[0016] In another embodiment, the radiation patternable material comprises one or more of the following EUV absorbing compounds: nickel acetate; nickel formate; nickel acetylacetonate; polynuclear nickel complexes; platinum and palladium complexes with azides, carbonates, oxalates, and acetylacetonates; polynuclear palladium and platinum complexes; silver and gold complexes with unsaturated hydrocarbons and phosphines; polynuclear silver and gold complexes; chromium complexes with arenes, thiocyanates, and bipyridines; and polynuclear chromium complexes with arenes, thiocyanates, and bipyridines.

[0017] In yet another embodiment, the radiation-sensitive material comprises an organic ligand selected from the group including acetate, formate, acetylacetonate, azide, carbonate, oxalate, unsaturated hydrocarbons, phosphines, arenes, thiocyanates, and bipyridines.

[0018] The present invention will be understood and appreciated more fully from the following detailed description of the embodiments thereof, taken in conjunction with the accompanying drawings, in which: [Brief description of the drawings]

[0019] [Figure 1] 2A-2C are illustrative diagrams of a cross-sectional view of an EUV mask during a process of manufacturing the EUV mask in accordance with an embodiment of the present invention. [Diagram 2] 2A-2C are illustrative diagrams of a cross-sectional view of an EUV mask during a process of manufacturing the EUV mask in accordance with an embodiment of the present invention. [Diagram 3] 2A-2C are illustrative diagrams of a cross-sectional view of an EUV mask during a process of manufacturing the EUV mask in accordance with an embodiment of the present invention. [Figure 4] 2A-2C are illustrative diagrams of a cross-sectional view of an EUV mask during a process of manufacturing the EUV mask in accordance with an embodiment of the present invention. [Diagram 5] 2A-2C are illustrative diagrams of a cross-sectional view of an EUV mask during a process of manufacturing the EUV mask in accordance with an embodiment of the present invention. [Figure 6] 2A-2C are illustrative diagrams of a cross-sectional view of an EUV mask during a process of manufacturing the EUV mask in accordance with an embodiment of the present invention. [Figure 7] 2A-2C are illustrative diagrams of a cross-sectional view of an EUV mask during a process of manufacturing the EUV mask in accordance with an embodiment of the present invention. [Figure 8] 1 is an illustrative diagram of a flow chart of a method for manufacturing an EUV mask, in accordance with an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] It will be understood that for simplicity and clarity, elements shown in the figures have not necessarily been drawn to scale. Furthermore, in various functional block diagrams, where applicable, two connected devices and / or elements are not necessarily shown as connected. In other examples, the grouping of certain elements in the functional block diagrams is merely for illustrative purposes and may not necessarily imply that they are in or embodied in a single physical entity.

[0021] Exemplary embodiments are described herein in the context of EUV lithography processes and associated EUV masks and mask material stacks, as well as materials used in the fabrication of the EUV masks. However, it should be understood that embodiments of the invention are not limited to these exemplary masks, but are instead more broadly applicable to a wide variety of different mask stacks, and their patterning techniques. These and numerous other variations on the disclosed structures will be apparent to those of skill in the art.

[0022] An exemplary embodiment includes forming a mask absorber layer on an EUV mask blank. The mask absorber layer can be formed by deposition techniques including, but not limited to, sublimation, plasma enhanced chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD), physical vapor deposition (PVD), and spin coating. It should also be noted that, herein, references to forming one layer or structure "on" or "over" another layer or structure are intended to be interpreted broadly and should not be interpreted as excluding the presence of one or more intervening layers or structures.

[0023] 1-7 illustratively depict a process for forming an EUV mask in accordance with one or more embodiments of the present invention. The figures show respective cross-sectional views of a portion of an EUV mask as the EUV mask is sequentially processed as part of a manufacturing process. It should be understood that the various elements and other features shown in the figures have been simplified for clarity and ease of illustration and have not necessarily been drawn to scale.

[0024] FIG. 1 is an illustrative diagram of a cross-sectional view of an EUV mask in a process of manufacturing an EUV mask according to an embodiment of the present invention. More specifically, FIG. 1 shows an EUV blank substrate 100 including an EUV mask substrate 110 and an EUV reflector multilayer 120 thereon. The EUV mask substrate 110 may be a substrate made of a low thermal expansion (LTE) material, such as, for example, fused silica, quartz, silicon carbide, or other low thermal expansion substances known in the art. The LTE material may be doped with a low amount of an inorganic compound, such as, for example, a transition metal oxide, to enhance the LTE properties of the EUV mask substrate 110.

[0025] The EUV reflector multilayer 120 may have a multilayer structure, for example, made of a transition metal molybdenum (Mo) layer and a silicon (Si) layer stacked alternately. In other words, the EUV reflector multilayer 120 may be made of a plurality of Mo layers and a plurality of Si layers in an alternating stacked format. The EUV reflector multilayer 120 may be formed on the EUV mask substrate 110, for example, through a plurality of deposition processes, with a total combined thickness reaching about 200 nm to about 500 nm. The EUV reflector multilayer 120 may function as a Bragg reflector that enhances or maximizes the reflection of radiation of a wavelength of 13.5 nm used in EUV lithography.

[0026] Figure 2 is an illustrative diagram of a cross section of an EUV mask in a manufacturing process of the EUV mask according to one embodiment of the present invention. More specifically, according to one embodiment, Figure 2 illustratively shows a process step of forming a layer of radiation sensitive material (310 in Figure 4) on an EUV blank substrate 100, more specifically on an EUV reflector multilayer 120 above an EUV mask substrate 110. Details of the radiation sensitive material layer, referred to herein as an RSM layer, including its material properties, are described in more detail below with reference to Figure 4.

[0027] 2 shows construction 200 with target material layer 220 attached to carrier substrate 210. Target material layer 220 may be the same radiation sensitive material (RSM) layer as RSM layer 310 and may be used to form RSM layer 310. During formation of RSM layer 310, target material layer 220 together with its carrier substrate 210 may be placed directly above EUV reflector multilayer 120 of EUV blank substrate 100.

[0028] The radiation sensitive material of the target material layer 220 can be deposited on the EUV reflector multilayer 120 on the EUV mask substrate 110 via a sublimation process. More specifically, embodiments of the present invention provide a method for sublimating the target material layer 220 of radiation sensitive material directly from a solid state to a vapor state by a heated holding substrate 210. For example, the target material layer 220 can be heated through the heated holding substrate 210 to a temperature ranging between 90 degrees Celsius and 400 degrees Celsius, thereby generating a vapor state 290 of the radiation sensitive material. The vapor state 290 of the radiation sensitive material can then be used to form the RSM layer 310, as described in more detail below.

[0029] The target material layer 220 may include one or more EUV absorbing metal elements, such as, for example, silver (Ag), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), or chromium (Cr), or combinations thereof. The target material layer 220 may also include one or more organic ligands from the group including acetate, formate, acetylacetonate, azide, carbonate, oxalate, unsaturated hydrocarbon, phosphine, arene, thiocyanate, and bipyridine. More generally, the target material layer 220 may include one or more EUV absorbing compounds made of one or more EUV absorbing metal elements Ag, Pt, Pd, Au, Ni, and Cr in combination with one or more organic ligands as listed above, in the form of mononuclear or polynuclear complexes.

[0030] Further illustrating the above as a non-limiting and non-exhaustive list, EUV absorbing compounds can include, for example, nickel acetate; nickel formate; nickel acetylacetonate; polynuclear nickel complexes; platinum and palladium complexes with azides, carbonates, oxalates, and acetylacetonates; polynuclear palladium and platinum complexes; silver and gold complexes with unsaturated hydrocarbons and phosphines; polynuclear silver and gold complexes; chromium complexes with arenes, thiocyanates, and bipyridines; polynuclear chromium complexes with arenes, thiocyanates, and bipyridines, and the like. However, embodiments of the present invention are not limited to this aspect. Those skilled in the art will understand that EUV absorbing compounds having other combinations of one or more EUV absorbing metal elements and one or more organic ligands, in mononuclear or polynuclear form, are possible and are fully contemplated herein as well.

[0031] 3 is an illustrative diagram of a cross section of an EUV mask in a manufacturing process of the EUV mask, in accordance with one embodiment of the present invention. More specifically, FIG. 3 illustratively shows another step in the process of forming an RSM layer 310.

[0032] 3 illustrates a structure 300 in which a portion of the target material layer 220 is deposited on the EUV reflector multilayer 120 as an RSM layer 310, while the remainder of the target material layer 220 remains on the carrier substrate 210 as a residual target material layer 320. More specifically, an embodiment of the present invention provides a method for turning the vapor state 290 of the radiation sensitive material of the target material layer 220 into a solid state by subjecting the vapor state 290 of the radiation sensitive material to a cooling process, thereby resulting in deposition of the radiation sensitive material on the EUV reflector multilayer 120 above the EUV mask substrate 110. For example, according to an embodiment of the present invention, the vapor state 290 of the radiation sensitive material may be disposed in the vicinity of a relatively cool surface of the EUV reflector multilayer 120, while the relatively cool surface of the EUV reflector multilayer 120 may be achieved by cooling the EUV blank substrate 100. According to one embodiment, the surface of the EUV reflector multilayer 120 may be cooled to a temperature ranging from about 10 degrees Celsius to about 90 degrees Celsius for a duration or period of about 1 to 100 minutes.

[0033] FIG. 4 is an alternative illustration of the structure 300 of FIG. 3, in which the remaining target material layer 320 with its carrier substrate 210 is not shown. More specifically, FIG. 4 illustratively shows an EUV mask blank 301 with an RSM layer 310 deposited on an EUV blank substrate 100, i.e., on an EUV reflector multilayer 120 above an EUV mask substrate 110. The RSM layer 310 may have a thickness ranging from about 50 nm to about 500 nm, more preferably from about 100 nm to about 200 nm. According to an embodiment of the invention, the RSM layer 310 may be subsequently lithographically patterned to form an EUV absorber or absorber layer, and for that reason may be referred to hereinafter as an imaging layer. Furthermore, the RSM layer 310 may be a radiation-patternable imaging layer, since it is a radiation-sensitive material.

[0034] It will be appreciated by those skilled in the art that the embodiment of the present invention for forming the RSM layer 310, i.e., radiation-patternable imaging layer, on the EUV blank substrate 100 is not limited to the above aspects. Various currently known or future developed methods and / or processes can be applied to form the RSM layer 310. For example, processes such as plasma enhanced chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD), physical vapor deposition (PVD), and spin-coating processes can be used to apply or form the RSM layer 310 on the EUV blank substrate 100.

[0035] As mentioned above, the RSM layer 310 is a layer of radiation sensitive material. In other words, the material properties of the RSM layer 310 make it responsive to exposure to certain ionizing radiation, such as electron beam (e-beam), and may be treated to become a patterned absorber layer. In other words, the RSM layer 310 is patternable by exposure to ionizing radiation, and thus may be referred to as a radiation patternable layer.

[0036] FIG. 5 illustrates a cross-section of an EUV mask in a manufacturing process of the EUV mask, according to an embodiment of the present invention. More specifically, an embodiment includes exposing the RSM layer 310 to ionizing radiation, such as electron beam (e-beam) exposure 430, to create a mask pattern 420. In other words, a portion or portions of the RSM layer 310 may be exposed to ionizing radiation to cause a change in the material properties of the RSM layer 310. For example, organic ligands within the exposed portions of the RSM layer 310 may be removed. The process of removing the organic ligands may be performed under a vacuum environment in a radiation exposure chamber. Being non-ionic and low molecular weight, the organic ligands volatilize and are pushed out of the radiation exposure chamber. In some cases, the sensitivity of the RSM layer 310 to radiation may be correlated to the ligand molecular weight, where the ligands modulate the RSM decomposition reaction rate.

[0037] After radiation exposure 430, the exposed portion of the RSM layer 310, i.e., the mask pattern 420 shown in FIG. 5, may be subjected to a densification process. In one embodiment, some densification process may also have already taken place naturally during the exposure process as a result of mass loss and volatilization of organic ligands. According to one embodiment, the densification process may be thermally enhanced during a subsequent development process after completion of the patternwise exposure step that creates the mask pattern 420. The densified mask pattern 420 may then be formed into an EUV absorber or absorber layer 510 (see FIG. 7).

[0038] FIG. 6 is an illustrative diagram of a cross section of an EUV mask in a manufacturing process of an EUV mask according to an embodiment of the present invention. More specifically, following the radiation exposure and densification process, an embodiment of the present invention includes applying a development process to remove the unexposed portions of the RSM layer 310, i.e., the remaining RSM layer 410, as shown in FIG. 5. In an embodiment, the development process may be a dry development process by sublimating the unexposed portions of the RSM layer 310 from the EUV mask blank 301. In other words, the remaining RSM layer 410 of the unexposed portions of the RSM layer 310 may be removed by sublimating it from the top surface of the EUV blank substrate 100. For example, the structure 400 may be exposed to a heated environment. The heated environment may be a stand-alone heat chamber or may be a load lock of a radiation exposure system adapted for substrate heating. The dry development process may be performed at a temperature of, for example, around 200 degrees Celsius to directly transform the remaining RSM layer 410 into a vapor state 490.

[0039] In another embodiment, the development process may be a wet development process that consists of applying a liquid developer that dissolves the unexposed portions of the RSM layer 310. The liquid developer may be, for example, an organic solvent selected from the group including alcohols, esters, ketones, and hydrocarbons. Examples of liquid developers are isopropanol, acetone, butyl acetate, and hexane.

[0040] 7 is an illustrative diagram of a cross section of an EUV mask in a manufacturing process of the EUV mask according to an embodiment of the present invention. More specifically, FIG. 7 illustratively shows a structure that is an EUV mask 500 having a patterned EUV absorber or absorber layer 510 on an EUV blank substrate 100 including an EUV reflector multilayer 120 and an EUV mask substrate 110. The patterned EUV absorber or absorber layer 510 may include one or more EUV absorbing metal elements such as Ag, Pt, Pd, Au, Ni, and Cr, for example. Additionally, the patterned EUV absorber or absorber layer 510 may possibly include traces of organic compounds such as C, H, O, N, P, or S, or combinations thereof, as a result of incomplete removal of all non-metallic compounds.

[0041] FIG. 8 is an illustrative diagram of a flow chart of a method of fabricating an EUV mask, according to an embodiment of the present invention. More specifically, the method embodiment includes forming an EUV reflector multilayer on an EUV mask substrate to form an EUV blank substrate (801). The EUV reflector multilayer may be a Bragg reflector layer that enhances reflection of 13.5 nm wavelength radiation in EUV lithography. The method embodiment further includes forming a radiation-patternable imaging layer of a radiation-sensitive material (RSM) on the EUV reflector multilayer to form an EUV mask blank (802). The RSM layer is sensitive to ionizing radiation, such as electron beam (e-beam), such that the imaging layer formed therefrom can be patternable through exposure to radiation. The method embodiment then includes exposing the radiation-patternable imaging layer to ionizing radiation to form an EUV absorber pattern (803). The method embodiment further includes removing the organic ligands in the exposed radiation patternable imaging layer while or subsequently densifying the exposed portions of the radiation patternable imaging layer, for example, through substrate heating (804). After densifying the exposed portions of the radiation patternable imaging layer, the method embodiment then includes removing the unexposed portions of the radiation patternable imaging layer (805). Removal of the unexposed portions of the radiation patternable imaging layer can be done, for example, via a sublimation process that causes the unexposed portions of the radiation patternable imaging layer to be removed from the EUV mask blank through a vapor state, finally completing the EUV mask with a patterned absorber layer (806). Removal of the unexposed portions of the radiation patternable imaging layer can also be done by a wet development process that causes the unexposed portions of the RSM layer to be removed from the EUV mask blank by dissolving them in a liquid developer, to complete the EUV mask with a patterned absorber layer.

[0042] In the above description, various materials and dimensions are provided for different elements. Unless otherwise specified, such materials are provided by way of example only, and the embodiments are not limited to only the specific examples provided. Similarly, unless otherwise specified, all dimensions are provided by way of example, and the embodiments are not limited to only the specific dimensions or ranges provided.

[0043] It should be understood that the various layers, structures, or regions, or combinations thereof, described above are not necessarily drawn to scale. Additionally, for ease of illustration, one or more layer, structure, and region types that are typically used to form semiconductor devices or structures may not be explicitly shown in a given drawing. This is not to be implied that the layers, structures, and regions not explicitly shown are omitted from the actual semiconductor structure.

[0044] Further, it should be understood that the embodiments discussed herein are not limited to the specific processing steps shown and described herein. In particular, with respect to semiconductor processing steps, it is emphasized that the description provided herein is not intended to be inclusive of all of the processing steps that may be used to form a functional semiconductor integrated circuit device. Rather, certain processing steps that are commonly used in forming semiconductor devices, such as wet cleaning and annealing steps, have been purposely not described herein for economy of description.

[0045] Terms such as "about" or "substantially" as used herein with respect to thickness, width, percentages, ranges, etc. are meant to indicate close or approximation, but not exact. For example, the term "about" or "substantially" as used herein means that a small margin of error may exist, such as, by way of example only, 1% or less from the recited amount. Also, in the figures, the illustrated scale of one layer, structure or region, or combination thereof, relative to another layer, structure or region, or combination thereof, is not necessarily intended to represent actual scale.

[0046] Semiconductor devices and methods of forming same in accordance with the above techniques may be employed in a variety of applications, hardware or electronic systems or combinations thereof, including, but not limited to, personal computers, communication networks, electronic commerce systems, portable communication devices (e.g., cellular and smart phones), solid state media storage devices, functional circuits, etc. Given the teachings provided herein, those skilled in the art will be able to envision other implementations and applications of embodiments of the invention.

[0047] In some embodiments, the techniques described above are used in connection with the manufacture of semiconductor integrated circuit devices, illustratively comprising, by way of non-limiting example, CMOS devices, MOSFET devices, and / or FinFET devices, and / or other types of semiconductor integrated circuit devices incorporating or otherwise using CMOS, MOSFET, and / or FinFET technology.

[0048] Thus, at least a portion of one or more of the semiconductor structures described herein can be implemented in an integrated circuit. The resulting integrated circuit chips can be distributed by a manufacturer in raw wafer form (i.e., as a single wafer having multiple unpackaged chips), as bare die, or in packaged form. In the latter case, the chips are packaged in a single-chip package (such as a plastic carrier or other higher level carrier having leads that are secured to a motherboard), or in a multi-chip package (e.g., a ceramic carrier having either surface interconnects or embedded interconnects, or both). In either case, the chips are then integrated with other chips, discrete circuit elements, or other signal processing devices, or a combination thereof, as part of either (a) an intermediate product, such as a motherboard, or (b) a final product. The final product can be any product that includes the integrated circuit chip, ranging from toys and other low-end applications to advanced computer products having displays, keyboards, or other input devices, and a central processor.

[0049] Although the description of various embodiments of the present invention has been presented for illustrative purposes, the description is not intended to be exhaustive or limited to the disclosed embodiments. Many changes and modifications will become apparent to those skilled in the art without departing from the scope of the described embodiments. The terms used in this specification have been selected to best explain the principles of the embodiments, practical applications, or technical improvements to the technology found in the market, or to enable other skilled in the art to understand the embodiments disclosed herein.

[0050] While certain features of the invention have been illustrated and described herein, numerous modifications, substitutions, changes, and equivalents will occur to those skilled in the art. Such modifications, variations, or alternative embodiments or combinations thereof may be made without departing from the scope of the invention, and are all herein considered to be within the scope of the invention. It is therefore to be understood that the appended claims are intended to cover all such modifications and variations that are within the scope of the invention.

[0051] In the preferred embodiment of the present invention described above, a radiation-patternable material is provided, comprising one or more extreme ultraviolet (EUV) absorbing metal elements and an organic ligand selected from the group comprising acetate, formate, acetylacetonate, azide, carbonate, oxalate, unsaturated hydrocarbon, phosphine, arene, thiocyanate and bipyridine, the radiation-patternable material being adapted to be deposited on the surface of an EUV blank substrate via a sublimation process to form an ultra-thin film. The ultra-thin film deposited on the surface of the EUV blank substrate is preferably adapted to be removed from the surface of the EUV blank substrate via another sublimation process. The one or more EUV absorbing metal elements preferably comprise one or more of silver (Ag), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni) and chromium (Cr). The material preferably comprises one or more of the following EUV absorbing compounds: nickel acetate; nickel formate; nickel acetylacetonate; polynuclear nickel complexes; platinum and palladium complexes with azides, carbonates, oxalates, and acetylacetonates; polynuclear palladium and platinum complexes; silver and gold complexes with unsaturated hydrocarbons and phosphines; polynuclear silver and gold complexes; chromium complexes with arenes, thiocyanates, and bipyridines; and polynuclear chromium complexes with arenes, thiocyanates, and bipyridines.

Claims

1. an EUV mask substrate; an EUV reflector multilayer on said EUV mask substrate; an imaging layer on said EUV reflector multilayer; and An extreme ultraviolet (EUV) mask blank comprising:

1. An extreme ultraviolet (EUV) mask blank, wherein the imaging layer is a layer of radiation-sensitive material including one or more of the EUV-absorbing metallic elements silver (Ag), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), and chromium (Cr), and is radiation-patternable.

2. 2. The EUV mask blank of claim 1, wherein the imaging layer comprises one or more organic ligands selected from the group consisting of acetate, formate, acetylacetonate, azide, carbonate, oxalate, unsaturated hydrocarbons, phosphines, arenes, thiocyanates, and bipyridines.

3. 2. The EUV mask blank of claim 1, wherein the imaging layer comprises one or more of the following EUV absorbing compounds: nickel acetate; nickel formate; nickel acetylacetonate; polynuclear nickel complexes; platinum and palladium complexes with azides, carbonates, oxalates, and acetylacetonates; polynuclear palladium and platinum complexes; silver and gold complexes with unsaturated hydrocarbons and phosphines; polynuclear silver and gold complexes; chromium complexes with arenes, thiocyanates and bipyridines; and polynuclear chromium complexes with arenes, thiocyanates and bipyridines.

4. 2. The EUV mask blank of claim 1, wherein the layer of radiation sensitive material is sublimated onto the EUV reflector multilayer to form the imaging layer.

5. 10. The EUV mask blank of claim 1, wherein the imaging layer is patternable through exposure to ionizing radiation.

6. 2. The EUV mask blank of claim 1, wherein the EUV reflector multilayer comprises a plurality of transition metal molybdenum (Mo) layers and a plurality of silicon (Si) layers stacked alternately.

7. 10. The EUV mask blank of claim 1, wherein the EUV mask substrate comprises a low thermal expansion material of fused silica, quartz, or silicon carbide.

8. 1. A method of forming an extreme ultraviolet (EUV) mask, comprising: sublimating a layer of radiation sensitive material onto a surface of an EUV blank substrate; exposing the layer of radiation sensitive material to ionizing radiation to form an EUV mask pattern; removing a portion of the layer of radiation-sensitive material from the surface of the EUV blank substrate; wherein said portion of said layer of radiation sensitive material that is removed is not exposed to said ionizing radiation.

9. The method of claim 8 , wherein removing the portion of the layer of radiation sensitive material comprises sublimating the portion of the layer of radiation sensitive material from the EUV blank substrate.

10. The method of claim 8 , wherein the EUV blank substrate comprises an EUV reflector multilayer formed on an EUV mask substrate.

11. 9. The method of claim 8, wherein the radiation-sensitive material comprises one or more of the EUV-absorbing metal elements silver (Ag), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), and chromium (Cr).

12. 9. The method of claim 8, wherein the radiation-sensitive material comprises one or more of the following EUV absorbing compounds: nickel acetate; nickel formate; nickel acetylacetonate; polynuclear nickel complexes; platinum and palladium complexes with azides, carbonates, oxalates, and acetylacetonates; polynuclear palladium and platinum complexes; silver and gold complexes with unsaturated hydrocarbons and phosphines; polynuclear silver and gold complexes; chromium complexes with arenes, thiocyanates, and bipyridines; and polynuclear chromium complexes with arenes, thiocyanates, and bipyridines.

13. 9. The method of claim 8, wherein the radiation-sensitive material comprises an organic ligand selected from the group consisting of acetate, formate, acetylacetonate, azide, carbonate, oxalate, unsaturated hydrocarbons, phosphines, arenes, thiocyanates, and bipyridines.

14. 14. The method of claim 13, wherein exposing the radiation-sensitive material to the ionizing radiation comprises removing the organic ligand from the portion of the radiation-sensitive material exposed to the ionizing radiation.

15. The method of claim 14 further comprising densifying the portion of the radiation sensitive material that is exposed to the ionizing radiation.

16. 10. The method of claim 8 , wherein the radiation-sensitive material comprises an EUV absorbing metal element and an organic ligand, and further comprising removing the organic ligand from portions of the radiation-sensitive material exposed to the ionizing radiation and densifying the portions of the radiation-sensitive material exposed to the ionizing radiation.

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