Method for forming a photomask

Abstract

The present disclosure provides a method for forming a photomask. The method includes providing a hard mask layer disposed on top of an absorber, a cover layer, and a plurality of layers disposed on a substrate. The method includes forming an intermediate layer above the hard mask layer, forming a photoresist layer above the intermediate layer, patterning the photoresist layer, etching the intermediate layer through the patterned photoresist layer, etching the hard mask layer through the patterned intermediate layer, and then etching the absorber through the patterned hard mask layer. In some embodiments, etching the hard mask layer through the patterned intermediate layer includes a dry etching process, the dry etching process having a first removal rate for the hard mask layer and a second removal rate for the intermediate layer, and a ratio of the first removal rate for the hard mask layer to the second removal rate for the intermediate layer is greater than 5.

Description

Technical Field

[0001] The present disclosure relates to a method for forming a photomask. Background Art

[0002] Lithography operations are some of the key operations in the semiconductor manufacturing process. Lithography techniques include ultraviolet lithography, deep ultraviolet lithography, and extreme ultraviolet lithography (EUVL). In this technology, the mask is an important component in the lithography operation. For example, in EUVL lithography, it is crucial to manufacture an EUV mask with high contrast having high reflectivity parts and high absorption parts. As dimensions shrink to make smaller features, newer integrated circuit technologies require finer patterns with narrower critical dimensions. Therefore, new and improved EUV mask film structures are needed to improve lithography resolution, and more robust processes are needed to manufacture such EUV masks. Summary of the invention

[0003] According to some embodiments of the present disclosure, a method for forming a photomask is provided, comprising: providing a hard mask layer, a covering layer, and a multilayer disposed on the top of an absorber; forming an intermediate layer on the hard mask layer; forming a photoresist layer on the intermediate layer; patterning the photoresist layer; etching the intermediate layer through the patterned photoresist layer; etching the hard mask layer through the patterned intermediate layer; and etching the absorber through the patterned hard mask layer.

[0004] According to some embodiments of the present disclosure, a method for forming a photomask is provided, comprising: forming a plurality of layers on a substrate; forming an absorber on a covering layer disposed on the plurality of layers; forming a hard mask layer on the absorber; forming an intermediate layer on the hard mask layer, wherein the intermediate layer comprises one or more selected from the group consisting of tantalum boron oxyoxide (TaBO), tantalum boron nitride (TaBN), tantalum boron oxynitride (TaBON), palladium (Pd) or nickel (Ni); forming a photoresist layer on the intermediate layer; patterning the photoresist layer; etching the intermediate layer through the patterned photoresist layer; and after etching the intermediate layer, performing a dry etching process on the hard mask layer, wherein the dry etching process has a first removal rate for the hard mask layer and a second removal rate for the intermediate layer, and a ratio of the first removal rate for the hard mask layer to the second removal rate for the intermediate layer is greater than 5.

[0005] According to some embodiments of the present disclosure, a method for forming a photomask is provided, comprising: forming an intermediate layer on an extreme ultraviolet film stack, the extreme ultraviolet film stack comprising a substrate, a plurality of layers on the substrate, a covering layer on the plurality of layers, an absorber on the covering layer, and a hard mask layer on the absorber; forming a photoresist layer on the intermediate layer, wherein the intermediate layer comprises one or more selected from the group consisting of silicon oxide (SiO), silicon oxynitride (SiON), silicon nitride (SiN), silicon boron nitride (SiBN), silicon borocarbide (SiBC), silicon carbide boron nitride (SiBCN), or polysiloxane; patterning the photoresist layer; patterning the intermediate layer through the patterned photoresist layer; patterning the hard mask layer through the patterned intermediate layer; and patterning the absorber through the patterned hard mask layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The present disclosure can be best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, in accordance with standard practice in the industry, various features are not drawn to scale and are only used for illustration purposes. In fact, the dimensions of various features may be arbitrarily increased or reduced for clarity of discussion.

[0007] Figure 1A , Figure 1B and Figure 1C FIG. 1 illustrates an EUV mask structure according to different embodiments of the present disclosure;

[0008] Figure 2A , Figure 2B and Figure 2C Schematically depicting strategies for manufacturing an EUV photomask according to various embodiments of the present disclosure;

[0009] Figure 3A , Figure 3B and Figure 3C Schematically illustrating sequential process steps of a method for manufacturing an EUV photomask according to different embodiments of the present disclosure;

[0010] Figure 4A , Figure 4B , Figure 4C , Figure 4D , Figure 4E and Figure 4F Schematically illustrating sequential process steps of a method for manufacturing an EUV photomask according to different embodiments of the present disclosure;

[0011] Figure 5 A flowchart is shown of an exemplary method of manufacturing an EUV photomask according to various embodiments of the present disclosure;

[0012] Figure 6 A flowchart is shown of another exemplary method for manufacturing an EUV photomask according to various embodiments of the present disclosure;

[0013] Figure 7 A flow chart is shown of another exemplary method of manufacturing an EUV photomask according to various embodiments of the present disclosure.

[0014]

Explanation of symbols

[0015] 10: Extreme ultraviolet light mask structure

[0016] 20: Photoresist layer

[0017] 30: Middle layer

[0018] 30-1: Middle layer

[0019] 30-2: Middle layer

[0020] 30-10: Middle layer

[0021] 40: Pattern

[0022] 50: Pattern

[0023] 100: Extreme ultraviolet light mask substrate

[0024] 101: Extreme Ultraviolet Photomask Substrate

[0025] 110: Hard mask layer

[0026] 120: Absorber

[0027] 130: Overlay

[0028] 140: Multilayer

[0029] 150: Base material

[0030] 160: Conductive layer

[0031] S100: Methods

[0032] S110: Steps

[0033] S120: Steps

[0034] S130: Steps

[0035] S140: Steps

[0036] S150: Steps

[0037] S160: Steps

[0038] S170: Steps

[0039] S200: Method

[0040] S210: Steps

[0041] S220: Steps

[0042] S230: Steps

[0043] S240: Steps

[0044] S250: Steps

[0045] S260: Steps

[0046] S270: Steps

[0047] S280: Steps

[0048] S300: Method

[0049] S310: Steps

[0050] S320: Steps

[0051] S330: Steps

[0052] S340: Steps

[0053] S350: Steps

[0054] S360: Steps DETAILED DESCRIPTION

[0055] It should be understood that the following content provides many different embodiments or examples for realizing the different features of the present disclosure. Specific embodiments or examples of components and configurations are described below to simplify the present disclosure. Of course, these are merely examples and are not intended to be limiting. For example, the size of the component is not limited to the disclosed range or value, but may depend on the process conditions and / or the desired characteristics of the device. In addition, in the following description, forming a first feature on or above a second feature may include an embodiment in which the first feature and the second feature are formed in direct contact, and may also include an embodiment in which additional features are formed between the first feature and the second feature so that the first feature and the second feature may not be in direct contact. For simplicity and clarity, various features may be arbitrarily drawn in different proportions.

[0056] Furthermore, spatially relative words (e.g., "below," "below," "below," "above," "above," and other related words) are used herein to simply describe the relationship of an element or feature as shown to another element or feature. When in use or operation, these spatially relative words cover different rotations of the device in addition to the rotations shown in the figures. Furthermore, these devices can be rotated (rotated 90 degrees or other angles), and the spatially relative descriptors used herein can be interpreted accordingly. In addition, the term "made of..." can mean "comprising" or "consisting of..." In the present disclosure, the phrase "one of A, B, and C" means "A, B and / or C" (A, B, C, A and B, A and C, B and C, or A, B and C), and does not mean one element from A, one element from B, and one element from C unless otherwise specified.

[0057] Embodiments of the present disclosure provide a method for manufacturing an extreme ultraviolet light mask. The present disclosure provides methods and techniques for enhancing lithography resolution, and a more robust process is required to manufacture such an extreme ultraviolet light mask. More specifically, the present disclosure relates to a new film structure for manufacturing an extreme ultraviolet light mask, which includes an intermediate layer between a photoresist layer and a hard mask layer, also referred to herein as a "three-layer strategy". This three-layer strategy can be integrated into a wafer process and implemented in extreme ultraviolet light lithography, wherein the intermediate layer is configured to have etching selectivity to the photoresist layer at the top and the hard mask layer below. According to different embodiments of the present disclosure, a relatively thin photoresist layer can be used to transfer a pattern to the intermediate layer, wherein the etching selectivity of the intermediate layer can alleviate the rounding problem caused by the loss of the photoresist layer, thereby increasing the pattern fidelity. The use of the intermediate layer can alleviate conventional problems, such as when the lateral dimension of the photoresist is much smaller than the thickness of the photoresist, such a high aspect ratio photoresist layer will cause the loss of the photoresist layer to cause the corners of the pattern to become rounded and / or the pattern to collapse. More specifically, the disclosed methods and techniques improve pattern resolution by reducing the thickness of the photoresist layer and improve pattern fidelity by improving etch resistance. The disclosed film scheme (film structure) can be clearly identified in an EUV photomask substrate and improve the current EUV photomask manufacturing process and promote the development of next generation EUV lithography.

[0058] Typically, the scanner used in EUV lithography uses light in the extreme ultraviolet (EUV) region, where the wavelength of light is about 1 nanometer to about 100 nanometers (e.g., 13.5 nanometers). The mask is a key component of the EUV lithography system. Since optical materials are opaque to EUV radiation, the EUV mask is a reflective mask. The circuit pattern is formed in an absorber layer disposed above the reflective structure. The absorber has a low EUV reflectivity (e.g., less than 3% to 5%). The present disclosure provides an EUV reflective mask with a fine pattern of a narrow critical dimension. Using the disclosed EUV mask scheme and process, a fine pattern with a high aspect ratio in the original photoresist layer is transferred to the absorber layer in the EUV mask with better pattern fidelity.

[0059] Figure 1A , Figure 1B and Figure 1C FIG. 1 is a diagram showing an EUV light mask structure 10 (also referred to as an EUV light mask) according to different embodiments of the present disclosure. Figure 1A , Figure 1B and Figure 1C As shown, a desired EUV mask having a circuit pattern is formed by an EUV mask structure 10, and the EUV mask structure 10 is illustrated as having a photoresist layer 20 and an intermediate layer 30 disposed on an EUV mask substrate 100. Figure 1A According to different embodiments of the present disclosure, an EUV photomask substrate 100 includes a hard mask layer 110, an absorber (also referred to as an absorber layer, an absorber layer) 120, a cover layer 130, a (reflective) multilayer 140, a substrate 150 (also referred to herein as a low-thermal expansion material (LTEM) 150, and a conductive layer 160. In some embodiments, an improved EUV photomask substrate 100 (which is referred to as an EUV photomask substrate 101) may include an intermediate layer 30, a hard mask layer 110, an absorber 120, a cover layer 130, a multilayer 140, a substrate 150, and a conductive layer 160. Unless otherwise explicitly stated, the EUV photomask substrate 101 is an EUV photomask substrate 100 (such as an EUV photomask substrate 100 having an intermediate layer 30) Figure 1A , Figure 1B and Figure 1C Therefore, in some embodiments, if the photomask substrate is referred to as an EUV photomask substrate 101, the hard mask layer 110 may be referred to as a first hard mask layer, and the intermediate layer 30 may be referred to as a second hard mask layer.

[0060] According to various embodiments, the method for manufacturing an EUV photomask starts with an EUV photomask substrate 100, and starts with an EUV photomask substrate 101 if an intermediate layer is already present on the substrate 100. In various embodiments, an intermediate layer 30 and a photoresist layer 20 are disposed on the EUV photomask substrate 100 to obtain an EUV photomask structure 10. According to various embodiments, an intermediate layer 30 is selected that has an etching selectivity to the photoresist layer 20 and the top layer (hard mask layer 110) of the EUV photomask substrate 100.

[0061] In various embodiments, the photoresist layer 20 comprises a positive chemically amplified resist (PCAR), a negative chemically amplified resist (NCAR), a non-chemically amplified resist (Non CAR) or an inorganic photoresist (e.g., a metal photoresist (MePR) or hydrogen silsesquioxane (HSQ)) that is sensitive to electron beam exposure. The thickness of the photoresist layer 20 is in the range of about 2 nm to about 150 nm, about 5 nm to about 100 nm, about 7 nm to about 75 nm, about 10 nm to about 50 nm, or about 70 nm to about 150 nm, and any thickness value or range therebetween.

[0062] In various embodiments, the intermediate layer 30 includes a metal or metal alloy film that can absorb extreme ultraviolet light. Non-limiting examples of metals that can be used as the intermediate layer 30 include transition metals (e.g., tantalum (Ta), palladium (Pd), nickel (Ni)) and their alloys (e.g., tantalum oxyboride (TaBO), tantalum boronitride (TaBN), etc.). In various embodiments, the intermediate layer 30 includes a silicon-based material (e.g., silicon oxide (SiO), silicon oxynitride (SiON), silicon nitride (SiN), silicon boronitride (SiBN), silicon borocarbide (SiBC), silicon boron carbide (SiBCN) or polysiloxane). The thickness of the intermediate layer 30 is in the range of about 2 nanometers to about 200 nanometers, about 2 nanometers to about 150 nanometers, about 2 nanometers to about 100 nanometers, about 2 nanometers to about 50 nanometers, or about 2 nanometers to about 30 nanometers, and includes any thickness value or range therebetween. In some embodiments, the intermediate layer 30 is formed by chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), physical vapor deposition (PVD) (sputtering), or any other suitable film forming method.

[0063] like Figure 1B As shown, according to different embodiments, the intermediate layer 30 includes two intermediate layers (also referred to herein as sublayers) 30-1 and 30-2 disposed between the photoresist layer 20 and the hard mask layer 110. In some embodiments, the intermediate layer 30-1 (bottom sublayer) may include a silicon-containing material, and the intermediate layer 30-2 (top sublayer) may include a transition metal-containing material. In some embodiments, the intermediate layer 30-1 may include a transition metal-containing material, and the intermediate layer 30-2 may include a silicon-containing material. Figure 1CAs shown, according to different embodiments, the intermediate layer 30 can be a multi-layer stack, that is, it is a plurality of intermediate layers (multiple sub-layers) 30-1, 30-2, ..., 30-10 having a combination of metal oxide and silicon-based materials, and the number of layers ranges from about 2 to about 10. According to different embodiments, the thickness of each of the intermediate layers 30-1, 30-2, ..., 30-10 is in the range of about 1 nanometer to about 30 nanometers, about 2 nanometers to about 30 nanometers, about 2 nanometers to about 20 nanometers, or about 1 nanometer to about 10 nanometers, and includes any thickness value or range therebetween. In some embodiments, the thickness of the multi-layer intermediate layer 30 is about 4 nanometers to about 200 nanometers, about 4 nanometers to about 150 nanometers, about 4 nanometers to about 100 nanometers, about 3 nanometers to about 50 nanometers, or about 3 nanometers to about 30 nanometers, and includes any thickness value or range therebetween. In some embodiments, the multi-layer intermediate layer 30 helps to maintain high pattern fidelity during hard mask layer etching. In some embodiments, the multi-layer intermediate layer 30 helps to reduce the loss of the photoresist layer.

[0064] In various embodiments, the intermediate layer 30 has an etch selectivity to the photoresist layer 20 and the hard mask layer 110. For example, the silicon-based intermediate layer 30 can be etched by a mixed gas plasma of carbon tetrafluoride / oxygen (CF4 / O2) at an etch rate of up to 600 angstroms per second (A / s), wherein the hard mask layer 110 comprising chromium oxynitride (CrON) can be etched at an etch rate of up to 40 angstroms per second. Under similar conditions, the etch rate of the photoresist layer 20 is about 220 angstroms per second to about 240 angstroms per second. Under certain conditions, the etch selectivity of the intermediate layer 30 to the hard mask layer 110 can be as high as 80:1, which can help facilitate the thinning of the intermediate layer 30. In various embodiments, the intermediate layer 30 includes the same material as the absorber layer 120. In various embodiments, the intermediate layer 30 includes a different material from the absorber layer 120.

[0065] In various embodiments, the function of the hard mask layer 110 is to transfer a pattern to the absorption layer. The hard mask layer 110 includes a metal layer (e.g., chromium (Cr) or tantalum (Ta)), or an alloy thereof (e.g., chromium oxynitride (CrON), tantalum oxide (TaO), tantalum oxyboride (TaBO)). In various embodiments, the hard mask layer 110 includes silicon, a silicon-based compound (e.g., silicon nitride (SiN) or silicon oxynitride (SiON)). The thickness of the hard mask layer 110 is in the range of about 2 nanometers to about 50 nanometers, about 3 nanometers to about 30 nanometers, about 4 nanometers to about 15 nanometers, or about 6 nanometers to about 10 nanometers, and includes any thickness value or range therebetween. In various embodiments, the hard mask layer 110 is formed by chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, physical vapor deposition (e.g., sputtering), or any other suitable film forming method.

[0066] In various embodiments, the thickness ratio of the photoresist layer 20 to the intermediate layer 30 is in a range from about 1:1 to about 75:1, from about 1:1 to about 50:1, from about 1:1 to about 25:1, and includes any range of ratios or ratio values ​​therebetween. In various embodiments, the thickness ratio of the intermediate layer 30 to the hard mask layer 110 is in a range from about 1:1 to about 100:1, from about 1:1 to about 75:1, from about 1:1 to about 50:1, from about 1:1 to about 25:1, and includes any range or ratio values ​​therebetween. This ratio can be selected so that the chemistry of the dry etch is adjusted to have a high etch selectivity in etching between the photoresist layer 20 and the hard mask layer 110 without losing pattern fidelity. In various embodiments, the thickness of the intermediate layer 30 is selected so that it does not undergo extended dry etch stripping that may damage the open hard mask layer area. In various embodiments, the thickness of the intermediate layer 30 is selected so that it can withstand the plasma during the hard mask layer etch without losing pattern fidelity.

[0067] In various embodiments, the absorber 120 includes a metal layer for absorbing extreme ultraviolet light on an extreme ultraviolet exposure tool. The absorber 120 includes a tantalum-based material. In some embodiments of the present disclosure, the absorber 120 has a multilayer structure as described below. In various embodiments, the absorber 120 includes a layer of tantalum (Ta), cobalt (Co), chromium (Cr), tellurium (Te), platinum (Pt), palladium (Pd), ruthenium (Ru), iridium (Ir), nickel (Ni) and / or alloys thereof (e.g., nitrides, carbides, oxides and / or boride derivatives).

[0068] In some embodiments, the anti-reflection layer (in Figures 1A to 1C In some embodiments, the anti-reflection layer is made of silicon oxide and has a thickness in the range of about 2 nanometers to about 10 nanometers. In some embodiments, a tantalum oxyboride (TaBO) layer having a thickness in the range of about 12 nanometers to about 18 nanometers is used as the anti-reflection layer. In some embodiments, the thickness of the anti-reflection layer is in the range of about 3 nanometers to about 6 nanometers. In some embodiments, the anti-reflection layer is formed by chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, physical vapor deposition, or any other suitable film forming method.

[0069] In various embodiments, the capping layer 130 includes a metal layer to protect the underlying multilayer 140 from being etched. In various embodiments, the capping layer 130 is disposed on the multilayer 140 to prevent oxidation of the multilayer 140. In various embodiments, the capping layer 130 includes ruthenium, a ruthenium alloy (e.g., ruthenium boride (RuB), ruthenium silicide (RuSi), or ruthenium niobide (RuNb)) or ruthenium oxide (e.g., ruthenium oxide (RuO2) or ruthenium oxyniobide (RuNbO)). The thickness of the capping layer 130 is in the range of about 1 nanometer to about 20 nanometers, about 2 nanometers to about 10 nanometers, or about 2 nanometers to about 4 nanometers, and includes any thickness value or range therebetween. In some embodiments, the capping layer 130 has a thickness of 3.5 nanometers ± 10%. In some embodiments, the capping layer 130 is formed by chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, physical vapor deposition (e.g., sputtering), or any other suitable film forming method. In some embodiments, a silicon (Si) layer is used as the capping layer 130 .

[0070] In various embodiments, the multilayer 140 includes a film stack containing up to about 60 pairs of molybdenum and silicon (also referred to herein as a "molybdenum / silicon (Mo / Si) stack"). In various embodiments, the multilayer 140 includes a film stack that includes pairs of molybdenum and silicon and a top silicon protective layer. In some embodiments, the multilayer 140 includes about 30 alternating layer pairs, about 40 alternating layer pairs, about 50 alternating layer pairs, or about 60 alternating layer pairs of each of silicon and molybdenum. In some embodiments, the reflectivity of the multilayer 140 is greater than about 70% for a wavelength of interest (e.g., 13.5 nanometers). In some embodiments, the silicon and molybdenum layer pairs are formed by chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, physical vapor deposition (sputtering), or any other suitable film formation method.

[0071] In various embodiments, each layer of silicon and molybdenum in multilayer 140 has a thickness of about 2 nanometers, about 3 nanometers, about 4 nanometers, about 5 nanometers, about 6 nanometers, about 7 nanometers, about 8 nanometers, about 9 nanometers, or about 10 nanometers, and any thickness value included therein. In some embodiments, the layers of silicon and molybdenum have approximately the same thickness. In some embodiments, the layers of silicon and molybdenum have different thicknesses. In some embodiments, the thickness of each silicon layer is about 4 nanometers, and the thickness of each molybdenum layer is about 3 nanometers.

[0072] In some embodiments, the multilayer 140 includes alternating layers of molybdenum and beryllium. In some embodiments, the number of layers in the multilayer 140 is in the range of about 20 to about 100, however any number of layers is allowed as long as sufficient reflectivity is maintained to image the target substrate. In some embodiments, the reflectivity is greater than about 70% for wavelengths of interest (e.g., 13.5 nanometers). In some embodiments, the multilayer 140 includes alternating layers of about 30 to about 60 molybdenum (Mo) and beryllium (Be). In other embodiments of the present disclosure, the multilayer 140 includes alternating layers of each of about 40 to about 50 molybdenum (Mo) and beryllium (Be).

[0073] In various embodiments, the substrate 150 includes titanium-doped silicon dioxide (SiO2), low thermal expansion glass, or quartz (e.g., fused silica or fused quartz). In some embodiments, the substrate 150 transmits light at visible wavelengths, a portion of infrared wavelengths near the visible spectrum (near infrared light), and a portion of ultraviolet wavelengths. In some embodiments, the substrate 150 absorbs extreme ultraviolet wavelengths and deep ultraviolet wavelengths close to the extreme ultraviolet. In some embodiments, the substrate 150 has a length and width of 152 mm and 152 mm, respectively, and has a thickness of about 0.25 inches.

[0074] In various embodiments, the conductive layer 160 comprises a metal layer used to mount an EUV photomask onto a photomask holder in an EUV exposure tool. In some embodiments, the conductive layer 160 comprises a tantalum-based material (e.g., tantalum boride (TaB) or other suitable tantalum-based conductive material). In some embodiments, the tantalum boride is crystalline. Crystalline tantalum borides include tantalum boride (TaB), tantalum pentaboride (Ta5B6), tantalum tetraboride (Ta3B4), and tantalum diboride (TaB2). In some embodiments, the tantalum boride is polycrystalline or amorphous. In some embodiments, the conductive layer 160 comprises a chromium-based conductive material (e.g., chromium nitride (CrN) or chromium oxynitride (CrON)). In some embodiments, the conductive layer 160 has a layer resistance of about 0.1 Ω / sq to about 20 Ω / sq, about 0.15 Ω / sq to about 15 Ω / sq, about 0.2 Ω / sq to about 10 Ω / sq, or about 0.3 Ω / sq to about 100 Ω / sq, and including any layer resistance value or range therebetween.

[0075] In some embodiments, the surface roughness Ra of the conductive layer 160 is equal to or less than 0.25 nanometers. In some embodiments, the surface roughness Ra of the conductive layer 160 is equal to or greater than 0.05 nanometers. In addition, in some embodiments, the flatness of the conductive layer 160 is equal to or less than 50 nanometers (in an extreme ultraviolet light mask). In some embodiments, the flatness of the conductive layer 160 is greater than 1 nanometer. In some embodiments, the thickness of the conductive layer 160 is in the range of about 50 nanometers to about 400 nanometers. In some embodiments, the conductive layer 160 has a thickness of about 50 nanometers to about 100 nanometers. In some embodiments, the thickness is in the range of about 65 nanometers to about 75 nanometers. In some embodiments, the conductive layer 160 is formed by atmospheric chemical vapor deposition, low pressure chemical vapor deposition, plasma enhanced chemical vapor deposition, laser enhanced chemical vapor deposition, atomic layer deposition, molecular beam epitaxy (MBE), physical vapor deposition (including thermal deposition, pulsed laser deposition, electron beam evaporation, ion beam assisted evaporation and sputtering) or any other suitable film forming method. In the case of chemical vapor deposition, in some embodiments, the source gas includes tantalum pentachloride (TaCl 5 ) and boron trichloride (BCl 3 ).

[0076] Figure 2A , Figure 2B and Figure 2C The process strategy for manufacturing an EUV photomask according to various embodiments of the present disclosure is schematically illustrated. The process strategy includes a three-layer strategy for achieving high pattern fidelity and lithography resolution.

[0077] Figure 2A , Figure 2B and Figure 2C The progression of the process strategy starting from the EUV reticle structure 10 in three exemplary stages of the process is schematically depicted. Figure 2A The EUV mask structure 10 is shown at a stage of fabrication, wherein the photoresist layer 20 is used as a mask to pattern an intermediate layer 30 disposed on a hard mask layer 110 on an absorber 120. The low aspect ratio photoresist layer 20 can be used as an etching mask to form the intermediate layer 30 through the low aspect ratio pattern defined by the photoresist layer 20. Once the pattern is etched in the intermediate layer 30, the photoresist layer 20 can be removed. Figure 2B FIG. 1 shows a stage of the EUV light mask structure 10 after the photoresist layer 20 is removed from the EUV light mask structure 10 . Figure 2B , the intermediate layer 30 can be used to etch the EUV photomask blank 100 with high fidelity and resolution. Figure 2C The EUV photomask structure 10 is shown at a stage where the intermediate layer 30 is used as a mask to pattern and etch the EUV photomask blank 100 or any layer of the EUV photomask blank 100. Figure 1AAs shown, according to various embodiments of the present disclosure, an EUV photomask substrate 100 refers to a layer stack including a hard mask layer 110 , an absorber 120 , a capping layer 130 , a multilayer 140 , a substrate 150 , and a conductive layer 160 .

[0078] Figure 3A , Figure 3B and Figure 3C The following schematically illustrates the sequential process steps of a method for manufacturing an EUV photomask according to different embodiments of the present disclosure. Figure 3A The EUV photomask substrate 100 according to various embodiments of the present disclosure includes a hard mask layer 110, an absorber 120, a capping layer 130, a multilayer 140, a substrate 150, and a conductive layer 160. In some embodiments, the EUV photomask substrate 100 may not include the hard mask layer 110, an absorber 120, a capping layer 130, a multilayer 140, a substrate 150, and a conductive layer 160. Figure 3A In some embodiments, the EUV photomask substrate 100 may include Figure 3A The layer stack shown may include one or more additional layers. Figure 3A The EUV photomask blank 100 shown in FIG. 1 can be formed by various suitable process technologies.

[0079] Figure 3B The manufacturing process is shown in FIG. 1 , wherein the intermediate layer 30 is disposed on the EUV photomask substrate 100. Figures 1A to 1C As described above, the intermediate layer 30 may be a single layer, or may include two intermediate layers (sub-layers) 30-1 and 30-2, or may be a multi-layer stack having multiple sub-layers (i.e., intermediate layers 30-1, 30-2, ..., 30-10), which are respectively illustrated and described in Figure 1A , Figure 1B and Figure 1C According to different embodiments, any intermediate layer including a single or multiple sublayers 30-1, 30-2, ..., 30-10 may include a silicon-containing material or a transition metal-containing material. The composition of the intermediate layers 30-1, 30-2, ..., 30-10 may be the same or different, so that at least two of the intermediate layers 30-1, 30-2, ..., 30-10 have alternating compositions, thicknesses, or different physical dimensions or chemical compositions. Similarly, as described above, the intermediate layer 30 including the intermediate layers 30-1, 30-2, ..., 30-10 may be formed by chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, physical vapor deposition (e.g., sputtering), or any other suitable film forming method.

[0080] Figure 3C The stage of the manufacturing process is shown, in which the photoresist layer 20 is disposed on the intermediate layer 30 which has been disposed on the EUV photomask substrate 100. Figure 1AAs described in , the photoresist layer 20 includes a positive chemical amplification resist, a negative chemical amplification resist, a non-chemical amplification resist layer, or an inorganic resist (e.g., a metal resist or a hydrogen silicic acid type) that is sensitive to electron beam exposure. According to different embodiments, the thickness of the deposited photoresist layer 20 can be in the range of about 2 nanometers to about 150 nanometers, about 5 nanometers to about 100 nanometers, about 7 nanometers to about 75 nanometers, about 10 nanometers to about 50 nanometers, or about 70 nanometers to about 150 nanometers, and any thickness value or range included therein.

[0081] Figure 4A , Figure 4B , Figure 4C , Figure 4D , Figure 4E and Figure 4F The following schematically illustrates the sequential process steps in the method for manufacturing the EUV light mask 10 according to different embodiments of the present disclosure. It should be understood that 4A to 4F Additional operations are provided before, during, and after the illustrated processes, and some of the operations described below may be replaced or eliminated as other embodiments of the method. The order of operations and / or processes may be interchanged.

[0082] like Figure 4A As shown, the EUV light mask structure 10 includes a photoresist layer 20 formed on an intermediate layer 30 that has been configured on an EUV light mask substrate 100. FIG. 3A to FIG. 3C ), a photoresist layer 20 and an intermediate layer 30 are disposed on an EUV photomask substrate 100 having a stack of a hard mask layer 110, an absorber 120, a capping layer 130, a multilayer 140, a substrate 150, and a conductive layer 160. Once the photoresist layer 20 is disposed on the intermediate layer 30, the photoresist layer 20 is exposed to actinic radiation in a pattern. The selectively exposed photoresist layer 20 is baked and developed to form a pattern in the photoresist layer 20. In some embodiments, the actinic radiation is an electron beam or an ion beam. In some embodiments, a plasma descum step is optionally performed to remove photoresist residues in the openings.

[0083] Figure 4BThe stage is shown after the photoresist layer 20 has been developed using a pattern 40, which may correspond to the pattern of semiconductor device features that will be formed by the EUV mask 10 in a subsequent operation. Once the pattern 40 is formed in the photoresist layer 20, a dry etch (or any other suitable process step) is performed to transfer the pattern 40 in the photoresist layer 20 to the intermediate layer 30. According to some embodiments, using the photoresist layer 20 as a mask to etch the intermediate layer 30 helps to reduce the rounding of the corners of the photoresist layer 20. In some embodiments, depending on the dry etching method used, the dry etching of the intermediate layer 30 may be less reactive to the photoresist layer 20. In some embodiments, when etching the intermediate layer 30, an etch having a high etch selectivity to the photoresist layer 20 is selected. When a high etch selectivity is selected, the photoresist layer 20 is not easily worn and thus the corner rounding caused during the dry etching of the intermediate layer 30 can be prevented. In some embodiments, the amount of corner rounding of the photoresist layer 20 during etching of the intermediate layer 30 is reduced compared to when the hard mask layer 110 is directly etched without the intermediate layer 30. In the case of directly etching the hard mask layer 110 without the intermediate layer 30 (the hard mask layer 110 may include chromium oxynitride (CrON) or chromium (Cr) with any percentage of oxygen and nitrogen), the hard mask layer 110 may be dry etched using a mixed gas of chlorine-containing gas (chlorine (Cl2), boron trichloride (BCl3), carbon tetrachloride (CCl4)) and oxygen. In some embodiments, an inert gas may be used during etching. In some embodiments, the dry etching of the intermediate layer 30 may be one of carbon tetrafluoride (CF4), trifluoromethane (CHF3), difluoromethane (CH2F2), methyl fluoride (CH3F), or a combination of these fluorine-containing gases.

[0084] According to various embodiments, a thinner layer of the photoresist layer 20 may be used, which may prevent collapse of high aspect ratio features during development of the photoresist layer 20. In some embodiments, the intermediate layer 30 may be thinner than the photoresist layer 20 because the intermediate layer 30 has a higher etch selectivity to the hard mask layer 110 than the photoresist layer 20 has to the hard mask layer 110. For example, a hard mask layer 110 including chromium oxynitride (CrON) may be etched by a mixed gas plasma of chlorine / oxygen (Cl2 / O2) at an etch rate of up to about 240 angstroms per second (A / s), where the etch rate of silicon dioxide (SiO2) may be only up to about 3 angstroms per second. Under similar conditions, the etch rate of the photoresist layer 20 is about 220 angstroms per second to about 240 angstroms per second. In some embodiments, the etch selectivity of the intermediate layer 30 to the hard mask layer 110 is about 80:1, which may help facilitate thinning of the intermediate layer 30.

[0085] According to different embodiments, the intermediate layer 30 may include transition metals and / or alloys thereof, and silicon-based materials. In some embodiments, the material of the intermediate layer 30 is selected to have a desired etching selectivity to the photoresist layer 20 and the hard mask layer 110. In some embodiments, for the hard mask layer 110 having chromium oxynitride (CrON), the intermediate layer 30 is selected to be one or more oxide materials (e.g., tantalum oxyboron nitride (TaBON) or silicon-based materials), which can be dry-etched with carbon tetrafluoride (CF4), trifluoromethane (CHF3), difluoromethane (CH2F2), fluoromethane (CH3F) or a combination of these fluorine-containing gases. In some embodiments, for a hard mask layer 110 having an oxide material (e.g., tantalum boron oxynitride (TaBON) or a silicon-based material), the intermediate layer 30 is selected to be a nitride material (e.g., chromium nitride (CrN) or tantalum nitride (TaN)), which can be dry-etched using a chlorine-containing gas (containing chlorine (Cl2), boron trichloride (BCl3), etc.) and optionally mixed with oxygen or an inert gas.

[0086] After the etching of the intermediate layer 30 is completed, the photoresist layer 20 can be stripped using a suitable stripping technique, which includes wet etching and dry etching, wherein the wet etching includes, for example, wet etching using an organic material, for example, using a mixture (SPM) of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2) or using a mixture (SPM) of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2) followed by a surface conditioning-1 (SC-1) treatment using an aqueous solution of ammonia and hydrogen peroxide as a cleaning step to remove the photoresist layer 20. To remove the organic thin layer or to remove particles, an organic solvent (tetraphenol ethylene glycidyl ether (PGEE) or propylene glycol monomethyl ether ester (PGMEA)) is used for washing, and dry etching includes dry etching using any oxidative plasma chemistry (oxygen (O2), carbon monoxide (CO), carbon dioxide (CO2), water (H2O) or a combination of these oxygen-containing gases) or any reducing plasma chemistry (nitrogen (N2), hydrogen (H2), ammonia (NH3), nitrite (N2H4) or a combination of these hydrogen and nitrogen gases). In some embodiments, the stripping of the photoresist layer 20 can be omitted until the etching of the hard mask layer 110 is completed.

[0087] Figure 4CThe intermediate layer 30 is shown at a stage after it has been etched (or otherwise formed) with the pattern 40. Once the pattern 40 has been transferred into the intermediate layer 30, the patterned intermediate layer 30 is used to form the pattern 40 in the hard mask layer 110 of the EUV photomask blank 100. According to various embodiments, the etching of the hard mask layer 110 can be accomplished by dry etching the hard mask layer 110 made of chromium oxynitride (CrON) or chromium (Cr) with any percentage of oxygen and nitrogen using a mixture of a chlorine-containing gas (chlorine (Cl2), boron trichloride (BCl3) and / or carbon tetrachloride (CCl4)) and oxygen. In some embodiments, an inert gas can be used during etching. In some embodiments, etching of the hard mask layer 110 can be accomplished by dry etching the hard mask layer 110 made of metal oxide or silicon-based material using carbon tetrafluoride (CF4), trifluoromethane (CHF3), difluoromethane (CH2F2), fluoromethane (CH3F), or a combination of these fluorine-containing gases.

[0088] After the etching of the hard mask layer 110 is completed, the intermediate layer 30 can be removed by over-etching the intermediate layer 30 using a plasma chemistry that reacts with the intermediate layer 30. In some embodiments, the over-etching can be done by dry etching with or without physical bombardment. In some embodiments, metal oxides or silicon-based materials can be over-etched with carbon tetrafluoride (CF4), trifluoromethane (CHF3), difluoromethane (CH2F2), fluoromethane (CH3F), or a combination of these fluorine-containing gases. In some embodiments, nitride materials such as chromium nitride (CrN) or tantalum nitride (TaN) can be over-etched with chlorine-containing gases such as chlorine (Cl2), boron trichloride (BCl3). In some embodiments, a gas mixed with oxygen or an inert gas can be used during etching.

[0089] According to various embodiments, a plasma chemistry may be selected that has a high etch selectivity for the hard mask layer 110 relative to the pattern-transferred intermediate layer 30. In other words, the etch rate of the chromium oxynitride (CrON) of the hard mask layer 110 may be adjusted by adjusting the gas ratio of chlorine (Cl2) and oxygen (O2), which will change the etch rate of the intermediate layer 30. In some embodiments, the etch rate ratio of the hard mask layer 110 relative to the intermediate layer 30 is about 10:1 or higher.

[0090] In some embodiments, in particular, when stripping of the photoresist layer 20 is omitted before etching of the hard mask layer 110 is completed, stripping of the photoresist layer 20 can be accomplished by any conventional stripping method using organic materials, such as wet etching using a mixture of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2) (SPM) or surface conditioning-1 (SC-1), washing using an organic solvent (tetraphenylethylene glycidyl ether (PGEE) or propylene glycol monomethyl ether ester (PGMEA)), or dry etching using any oxidative plasma chemistry (oxygen (O2), carbon monoxide (CO), carbon dioxide (CO2), water (H2O) or a combination of these oxygen-containing gases) or any reducing plasma chemistry (nitrogen (N2), hydrogen (H2), ammonia (NH3), nitrile (N2H4) or a combination of these hydrogen and nitrogen gases). In these embodiments, the oxidative or reducing dry etching methods can selectively remove or strip the photoresist layer 20 because these etching methods may not react with the intermediate layer 30.

[0091] Figure 4D The stage is shown after the hard mask layer 110 has been etched (or otherwise formed) with the pattern 40. Once the pattern 40 has been transferred into the hard mask layer 110, the pattern 40 is formed in the absorber 120 by dry etching the exposed portions of the pattern 40 in the absorber 120 using the patterned hard mask layer 110 as an etch mask. A dry etch (or any suitable wet etch) may be performed to remove the exposed portions in the absorber layer 120 to form the pattern 40 in the absorber 120. Once the pattern 40 has been transferred to the absorber 120, the remaining portions of the hard mask layer 110 may be removed by over-etching the hard mask layer 110 using a plasma chemistry that reacts with the hard mask layer 110. In some embodiments, the over-etching may be accomplished by dry etching with or without physical bombardment. In some embodiments, metal oxides or silicon-based materials may be overetched with carbon tetrafluoride (CF4), trifluoromethane (CHF3), difluoromethane (CH2F2), fluoromethane (CH3F), or a combination of these fluorine-containing gases. In some embodiments, nitride materials such as chromium nitride (CrN) or tantalum nitride (TaN) may be overetched with chlorine-containing gases such as chlorine (Cl2), boron trichloride (BCl3). In some embodiments, a gas mixed with oxygen or an inert gas may be used during etching.

[0092] Figure 4EThe absorber 120 is shown after it has been etched (or otherwise formed) with the pattern 40. Once the pattern 40 is transferred into the absorber 120, additional etching of the capping layer 130 or the multilayer 140 can be performed. In some embodiments, another pattern 50 can be transferred into the EUV mask 10 by repeating another set of suitable processing steps (e.g., by using another (second) photoresist layer to form the pattern and using it as an etch mask to perform etching (dry etching or wet etching) in the EUV mask 10). According to various embodiments, the pattern 50 defines a black border pattern of the EUV mask 10.

[0093] Figure 4F The stage after the pattern 50 has been transferred to the EUV mask 10 is shown. Figure 4F As shown, pattern 50 is transferred into cover layer 130 and multilayer 140. Once the pattern transfer of pattern 50 is completed, the second photoresist layer can be removed through a suitable photoresist stripper to expose the upper surface of absorber 120 (which has patterns 40 and 50 defined in absorber 120). In some embodiments of the present disclosure, pattern 50 in absorber 120, cover layer 130, and multilayer 140 defines a black boundary of EUV photomask 10. After removal of the second photoresist layer, EUV photomask 10 undergoes a cleaning operation, inspection, and repair of EUV photomask 10 as needed to provide a completed EUV photomask 10.

[0094] Figure 5A flow chart of a method S100 for manufacturing an EUV photomask according to various embodiments of the present disclosure is depicted. According to various embodiments, the method S100 includes providing a hard mask layer disposed on top of an absorber, a capping layer, and a plurality of layers disposed on a substrate in step S110. In some embodiments, the hard mask layer includes a metal layer (e.g., chromium (Cr) or tantalum (Ta)) or an alloy thereof (e.g., chromium oxynitride (CrON), tantalum boride (TaB), tantalum oxide (TaO), tantalum oxyboride (TaBO), or tantalum boronitride (TaBN)), or a silicon-based compound (e.g., silicon nitride (SiN) or silicon oxynitride (SiON)). The thickness of the hard mask layer is in a range of about 2 nm to about 50 nm, about 3 nm to about 30 nm, about 4 nm to about 15 nm, or about 6 nm to about 10 nm. In various embodiments, the hard mask layer is formed by chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, physical vapor deposition (e.g., sputtering), or any other suitable film forming method. In some embodiments, the absorber includes a metal layer for absorbing extreme ultraviolet light on an extreme ultraviolet exposure tool. The absorber includes a tantalum-based material. In some embodiments of the present disclosure, the absorber has a multilayer structure as described below. In different embodiments, the absorber includes a layer of tantalum (Ta), cobalt (Co), chromium (Cr), tellurium (Te), platinum (Pt), palladium (Pd), ruthenium (Ru), iridium (Ir), nickel (Ni) and / or alloys thereof (e.g., nitrides, carbides, oxides and / or derivatives of borides). In some embodiments, the capping layer includes a metal layer, such as but not limited to ruthenium, a ruthenium alloy (e.g., ruthenium boride (RuB), ruthenium silicide (RuSi) or ruthenium niobide (RuNb)) or ruthenium oxide (e.g., ruthenium oxide (RuO2) or ruthenium oxyniobide (RuNbO)). The thickness of the capping layer is in the range of about 1 nanometer to about 20 nanometers, about 2 nanometers to about 10 nanometers, or about 2 nanometers to about 4 nanometers, and includes any thickness value or range therebetween. In some embodiments, the multilayer includes a film stack comprising molybdenum and silicon pairs, which includes about 30 alternating layer pairs, about 40 alternating layer pairs, about 50 alternating layer pairs, or about 60 alternating layer pairs of each of silicon and molybdenum. In some embodiments, this multilayer includes up to 50 pairs of molybdenum and silicon layer pairs, and a top silicon protective layer. In some embodiments, the reflectivity of the multilayer is higher than about 70% for the wavelength of interest (e.g., 13.5 nanometers). In some embodiments, the substrate includes titanium-doped silicon oxide (SiO2), low thermal expansion glass or quartz (e.g., fused silica or fused quartz). In some embodiments, the substrate transmits visible light wavelengths, a portion of infrared light wavelengths (near infrared light) near the visible spectrum, and a portion of ultraviolet light wavelengths. In some embodiments, the substrate absorbs extreme ultraviolet light wavelengths and deep ultraviolet light wavelengths close to this extreme ultraviolet light.

[0095] The method S100 includes forming an intermediate layer over the hard mask layer at step S120. In some embodiments, the thickness of the intermediate layer is in a range of 2 nm to 200 nm. In some embodiments, the thickness of the intermediate layer is in a range of about 2 nm to about 150 nm, about 2 nm to about 100 nm, about 2 nm to about 50 nm, or about 2 nm to about 30 nm. In some embodiments, the intermediate layer includes one or more selected from the group consisting of tantalum boroide (TaBO), tantalum boronitride (TaBN), tantalum oxyboronitride (TaBON), palladium (Pd), nickel (Ni), silicon oxide (SiO), silicon oxynitride (SiON), silicon nitride (SiN), silicon boronitride (SiBN), silicon borocarbide (SiBC), silicon borocarbide nitride (SiBCN), or polysiloxane. In some embodiments, the intermediate layer includes a top sublayer and a bottom sublayer, wherein the top sublayer includes a silicon-containing material and the bottom sublayer includes a transition metal-containing material, or vice versa. In some embodiments, the intermediate layer includes a plurality of sublayers, wherein at least one sublayer includes a metal-containing material and at least another sublayer includes a silicon-containing material. In some embodiments, the plurality of intermediate layers may be etched using mixed gases in different proportions, such as chlorine-containing, fluorine-containing, and oxygen-containing gases, and an inert carrier gas (e.g., helium (He) or argon (Ar)) may be added. Under some conditions, the plurality of intermediate layers may help control fine critical dimensions during etching.

[0096] The method S100 includes forming a photoresist layer over the intermediate layer in step S130. In some embodiments, the photoresist layer includes a positive type chemical amplification resist, a negative type chemical amplification resist, or a non-chemical amplification resist layer that is sensitive to electron beam exposure. In some embodiments, the thickness of the photoresist layer 20 is in a range of about 2 nanometers to about 120 nanometers, about 5 nanometers to about 100 nanometers, about 7 nanometers to about 75 nanometers, about 10 nanometers to about 50 nanometers, or about 70 nanometers to about 120 nanometers.

[0097] The method S100 includes patterning the photoresist layer in step S140. In some embodiments, patterning the photoresist layer includes exposing the photoresist layer to actinic radiation after forming the pattern via an electron beam or an ion beam. After exposure to the actinic radiation, the exposed photoresist layer is baked and developed to form a pattern in the photoresist layer. Once the photoresist layer 20 has a pattern in the photoresist layer, the patterned photoresist layer can be used to form the same pattern in a layer below (e.g., an intermediate layer) during the manufacturing process of the mask.

[0098] Method S100 includes etching the intermediate layer through the patterned photoresist layer in step S150. In some embodiments, etching includes dry etching (or any other suitable process step), which can transfer the pattern in the photoresist layer to the intermediate layer. In some embodiments, using the photoresist layer as a mask to etch the intermediate layer can reduce the rounding of the corners of the photoresist layer. In some embodiments, when etching the intermediate layer, an etch with high etch selectivity to the photoresist layer is selected. When a high etch selectivity is selected, the photoresist layer is not easily worn and thus prevents the rounding of the corners caused during the dry etching of the intermediate layer. In some embodiments, the dry etching of the intermediate layer can be one of carbon tetrafluoride (CF4), trifluoromethane (CHF3), difluoromethane (CH2F2), fluoromethane (CH3F) or a combination of these fluorine-containing gases.

[0099] Method S100 includes etching the hard mask layer through the patterned intermediate layer at step S160. According to different embodiments, etching of the hard mask layer can be performed by dry etching the hard mask layer 110 made of chromium oxynitride (CrON) or chromium (Cr) and having any percentage of oxygen and nitrogen with a mixed gas of chlorine-containing gas (chlorine (Cl2), boron trichloride (BCl3) and / or carbon tetrachloride (CCl4)) and oxygen. In some embodiments, an inert gas can be used during etching. In some embodiments, etching of the hard mask layer can be performed by dry etching the hard mask layer made of metal oxide or silicon-based material with carbon tetrafluoride (CF4), trifluoromethane (CHF3), difluoromethane (CH2F2), fluoromethane (CH3F) or a combination of these fluorine-containing gases. In some embodiments, an inert gas can be used during etching. In some embodiments, a hard mask layer including chromium oxynitride (CrON) can be etched by a mixed gas plasma of chlorine / oxygen (Cl2 / O2) at an etch rate of up to about 240 angstroms / second.

[0100] The method S100 includes etching the absorber through the patterned hard mask layer in step S170. In some embodiments, etching the hard mask layer through the patterned intermediate layer includes a dry etching process having a first removal rate for the hard mask layer and a second removal rate for the intermediate layer, and a ratio of the first removal rate for the hard mask layer to the second removal rate for the intermediate layer is greater than 5.

[0101] In some embodiments, the absorber comprises tantalum, one or more selected from the group consisting of tantalum, cobalt, chromium, tellurium, platinum, palladium, palladium, ruthenium, iridium, nickel, and / or alloys thereof (e.g., nitride, carbide, oxide, and / or boride derivatives). In some embodiments, the hard mask layer comprises chromium oxynitride (CrON) and has a thickness between 2 nm and 15 nm, and / or the capping layer comprises ruthenium.

[0102] Figure 6 A flow chart of a method S200 for manufacturing an extreme ultraviolet light mask according to different embodiments of the present disclosure is depicted. Method S200 includes forming a multilayer above a substrate at step S210. In some embodiments, the multilayer includes a film stack comprising molybdenum and silicon pairs, which includes about 30 alternating layer pairs, about 40 alternating layer pairs, about 50 alternating layer pairs, or about 60 alternating layer pairs of each of silicon and molybdenum. In some embodiments, this multilayer includes up to 50 pairs of molybdenum and silicon layer pairs, and a top silicon protective layer. In some embodiments, the reflectivity of the multilayer is greater than about 70% for wavelengths of interest (e.g., 13.5 nanometers). In different embodiments, each layer of silicon and molybdenum in the multilayer has a thickness of about 2 nanometers, about 3 nanometers, about 4 nanometers, about 5 nanometers, about 6 nanometers, about 7 nanometers, about 8 nanometers, about 9 nanometers, or about 10 nanometers. In some embodiments, the layers of silicon and molybdenum have approximately the same thickness. In some embodiments, the layers of silicon and molybdenum have different thicknesses. In some embodiments, each silicon layer has a thickness of approximately 4 nanometers, and each molybdenum layer has a thickness of approximately 3 nanometers.

[0103] In some embodiments, the multilayer includes alternating layers of molybdenum and beryllium. In some embodiments, the number of layers in the multilayer is in the range of about 20 to about 100, however any number of layers is permitted as long as sufficient reflectivity is maintained to image the target substrate. In some embodiments, the reflectivity is greater than about 70% for wavelengths of interest (e.g., 13.5 nanometers). In some embodiments, the multilayer includes about 30 to about 60 alternating layers of molybdenum (Mo) and beryllium (Be). In other embodiments of the present disclosure, the multilayer 140 includes about 40 to about 50 alternating layers of each of molybdenum (Mo) and beryllium (Be). In some embodiments, silicon and molybdenum layer pairs and / or silicon and beryllium pairs are formed by chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, physical vapor deposition (sputtering), or any other suitable film forming method.

[0104] The method S200 includes forming an absorber over a capping layer disposed on the multilayer at step S220. The method S200 includes forming a hard mask layer over the absorber at step S230. The method S200 also includes forming an intermediate layer over the hard mask layer at step S240. According to different embodiments, the intermediate layer includes one or more selected from the group consisting of tantalum boron oxide (TaBO), tantalum boron nitride (TaBN), tantalum boron oxynitride (TaBON), palladium (Pd), or nickel (Ni). In some embodiments, the intermediate layer includes a plurality of sublayers, wherein at least one sublayer includes a metal-containing material and at least another sublayer includes a silicon-containing material. In some embodiments, the plurality of sublayers include a first sublayer and a second sublayer, wherein the first sublayer includes a silicon-containing material, the second sublayer includes a transition metal-containing material, and the first sublayer and the second sublayer are alternating pairs.

[0105] The method S200 further includes forming a photoresist layer on the middle layer in step S250. The method S200 includes patterning the photoresist layer in step S260. The method S200 includes etching the middle layer through the patterned photoresist layer in step S270.

[0106] The method S200 includes, in step S280, performing a dry etching process on the hard mask layer after etching the intermediate layer. The dry etching process has a first removal rate for the hard mask layer and a second removal rate for the intermediate layer, and a ratio of the first removal rate for the hard mask layer to the second removal rate for the intermediate layer is greater than 5. In some embodiments, the thickness of each sub-layer is in a range of 2 nanometers to 30 nanometers, and / or the thickness of the intermediate layer is in a range of 4 nanometers to 200 nanometers. In some embodiments, the intermediate layer includes one or more selected from the group consisting of tantalum boron oxide (TaBO), tantalum boron nitride (TaBN), tantalum oxyboron nitride (TaBON), palladium (Pd), nickel (Ni), silicon oxide (SiO), silicon oxynitride (SiON), silicon nitride (SiN), silicon boron nitride (SiBN), silicon borocarbide (SiBC), silicon borocarbide nitride (SiBCN), or polysiloxane. In some embodiments, the absorber comprises tantalum, one or more selected from the group consisting of tantalum, cobalt, chromium, tellurium, platinum, palladium, palladium, ruthenium, iridium, nickel, and / or alloys thereof (e.g., nitride, carbide, oxide, and / or boride derivatives). In some embodiments, the hard mask layer comprises chromium oxynitride (CrON) and has a thickness between 2 nm and 15 nm, and / or the capping layer comprises ruthenium, and the multilayer comprises a plurality of up to 50 pairs of molybdenum and silicon layer pairs. In some embodiments, the method further comprises etching the absorber through the patterned hard mask layer.

[0107] Figure 7A flow chart of a method S300 for manufacturing an EUV photomask according to various embodiments of the present disclosure is depicted. The method S300 includes forming an intermediate layer on an EUV film stack in step S310, the EUV film stack including a substrate, a multilayer on the substrate, a capping layer on the multilayer, an absorber on the capping layer, and a hard mask layer on the absorber. The method S300 includes forming a photoresist layer over the intermediate layer in step S320, wherein the intermediate layer includes one or more selected from the group consisting of silicon oxide (SiO), silicon oxynitride (SiON), silicon nitride (SiN), silicon boron nitride (SiBN), silicon borocarbide (SiBC), silicon carbide boron nitride (SiBCN), or polysiloxane. The method S300 also includes patterning the photoresist layer in step S330. The method S300 includes patterning the intermediate layer by using the patterned photoresist layer in step S340. The method S300 includes patterning the hard mask layer by using the patterned intermediate layer at step S350. The method S300 includes patterning the absorber by using the patterned hard mask layer at step S360. In some embodiments, patterning the hard mask layer includes etching the hard mask layer by a dry etching process using the patterned intermediate layer as a mask, wherein the dry etching process has a first removal rate for the hard mask layer and a second removal rate for the intermediate layer, and a ratio of the first removal rate for the hard mask layer to the second removal rate for the intermediate layer is greater than about 5. In some embodiments, the intermediate layer includes a plurality of sublayers, wherein at least one sublayer includes a metal-containing material and at least another sublayer includes a silicon-containing material. In some embodiments, each sublayer has a thickness in a range of 2 nanometers to 30 nanometers, and / or the intermediate layer has a thickness in a range of 4 nanometers to 200 nanometers. In some embodiments, the absorber includes tantalum, one or more selected from the group consisting of tantalum, cobalt, chromium, tellurium, platinum, palladium, palladium, ruthenium, iridium, nickel, and / or alloys thereof (e.g., nitrides, carbides, oxides, and / or borides).

[0108] In the present disclosure, a method of manufacturing an EUV photomask by using an intermediate layer to enhance the etch selectivity between a hard mask layer and a photoresist layer is implemented. The present disclosure provides methods and techniques for enhancing lithography resolution and a more robust process required to manufacture such an EUV photomask. The disclosed manufacturing strategy can be used in conjunction with the disclosed membrane structure for EUV photomask manufacturing to improve current EUV photomask manufacturing processes and facilitate the development of next generation EUV lithography. It will be understood that not all benefits need to be discussed herein, that specific benefits are not required for all embodiments or examples, and that other embodiments or examples may provide different benefits.

[0109] According to one aspect of the present disclosure, a method for forming a photomask is provided. The method includes providing a hard mask layer disposed on top of an absorber, a cover layer, and a plurality of layers disposed on a substrate. The method includes forming an intermediate layer above the hard mask layer, forming a photoresist layer above the intermediate layer, patterning the photoresist layer, etching the intermediate layer through the patterned photoresist layer, etching the hard mask layer through the patterned intermediate layer, and etching the absorber through the patterned hard mask layer. In some embodiments, etching the hard mask layer through the patterned intermediate layer includes a dry etching process having a first removal rate for the hard mask layer and a second removal rate for the intermediate layer, and a ratio of the first removal rate for the hard mask layer to the second removal rate for the intermediate layer is greater than 5. In some embodiments, the thickness of the intermediate layer is in a range of 2 nanometers to 200 nanometers. In some embodiments, the intermediate layer includes one or more selected from the group consisting of tantalum boroide (TaBO), tantalum boronitride (TaBN), tantalum oxyboronitride (TaBON), palladium (Pd), nickel (Ni), silicon oxide (SiO), silicon oxynitride (SiON), silicon nitride (SiN), silicon boronitride (SiBN), silicon borocarbide (SiBC), silicon borocarbide nitride (SiBCN), or polysiloxane. In some embodiments, the intermediate layer includes a top sublayer and a bottom sublayer, wherein the top sublayer includes a silicon-containing material and the bottom sublayer includes a transition metal-containing material, or vice versa. In some embodiments, the intermediate layer includes a plurality of sublayers, wherein at least one sublayer includes a metal-containing material and at least another sublayer includes a silicon-containing material. In some embodiments, the absorber includes tantalum, one or more selected from the group consisting of tantalum, cobalt, chromium, tellurium, platinum, palladium, palladium, ruthenium, iridium, nickel, and / or alloys thereof (e.g., derivatives of nitrides, carbides, oxides, and / or borides). In some embodiments, the hard mask layer comprises chromium oxynitride (CrON) and has a thickness between 2 nm and 15 nm, and / or the capping layer comprises ruthenium. In some embodiments, the multilayer comprises a plurality of molybdenum and silicon layer pairs, up to 50 pairs, and a top silicon protective layer.

[0110] According to one aspect of the present disclosure, a method for forming a photomask is provided. The method includes forming a plurality of layers above a substrate, forming an absorber above a capping layer disposed on the plurality of layers, forming a hard mask layer above the absorber, and forming an intermediate layer above the hard mask layer. The intermediate layer includes a plurality of sublayers, wherein at least one sublayer includes a metal-containing material, and at least another sublayer includes a silicon-containing material. The method also includes forming a photoresist layer above the intermediate layer, patterning the photoresist layer, etching the intermediate layer through the patterned photoresist layer, and after etching the intermediate layer, performing a dry etching process on the hard mask layer. The dry etching process has a first removal rate for the hard mask layer and a second removal rate for the intermediate layer, and the ratio of the first removal rate for the hard mask layer to the second removal rate for the intermediate layer is greater than 5. In some embodiments, the plurality of sublayers include a first sublayer and a second sublayer, the first sublayer includes a silicon-containing material, and the second sublayer includes a transition metal-containing material, wherein the first sublayer and the second sublayer are an alternating pair. In some embodiments, each sub-layer has a thickness between 2 nm and 30 nm, and / or the intermediate layer has a thickness between 4 nm and 200 nm. In some embodiments, the intermediate layer comprises one or more selected from the group consisting of tantalum boroide (TaBO), tantalum boronitride (TaBN), tantalum oxyboronitride (TaBON), palladium (Pd), nickel (Ni), silicon oxide (SiO), silicon oxynitride (SiON), silicon nitride (SiN), silicon boronitride (SiBN), silicon borocarbide (SiBC), silicon borocarbide nitride (SiBCN), or polysiloxane. In some embodiments, the absorber comprises tantalum, one or more selected from the group consisting of tantalum, cobalt, chromium, tellurium, platinum, palladium, palladium, ruthenium, iridium, nickel, and / or alloys thereof (e.g., derivatives of nitrides, carbides, oxides, and / or borides). In some embodiments, the hard mask layer comprises chromium oxynitride (CrON) and has a thickness between 2 nm and 15 nm, and / or the capping layer comprises ruthenium, and the multilayer comprises up to 50 pairs of molybdenum and silicon layer pairs. In some embodiments, the method further comprises etching the absorber through the patterned hard mask layer.

[0111] According to one aspect of the present disclosure, a method for forming a photomask is provided. The method includes forming an intermediate layer on an extreme ultraviolet film stack, the extreme ultraviolet film stack including a substrate, a plurality of layers on the substrate, a capping layer on the plurality of layers, an absorber on the capping layer, and a hard mask layer on the absorber. The method includes forming a photoresist layer over the intermediate layer, wherein the intermediate layer includes one or more selected from the group consisting of tantalum boron oxide (TaBO), tantalum boron nitride (TaBN), tantalum oxyboron nitride (TaBON), palladium (Pd), nickel (Ni), silicon oxide (SiO), silicon oxynitride (SiON), silicon nitride (SiN), silicon boron nitride (SiBN), silicon borocarbide (SiBC), silicon borocarbide nitride (SiBCN), or polysiloxane. The method also includes patterning the photoresist layer, patterning the intermediate layer by using the patterned photoresist layer, patterning the hard mask layer by using the patterned intermediate layer, and patterning the absorber by using the patterned hard mask layer. In some embodiments, patterning the hard mask layer includes etching the hard mask layer by a dry etching process using the patterned intermediate layer as a mask, wherein the dry etching process has a first removal rate for the hard mask layer and a second removal rate for the intermediate layer, and a ratio of the first removal rate for the hard mask layer to the second removal rate for the intermediate layer is greater than about 5. In some embodiments, the intermediate layer includes a plurality of sub-layers, wherein at least one sub-layer includes a metal-containing material and at least another sub-layer includes a silicon-containing material. In some embodiments, each sub-layer has a thickness between 2 nanometers and 30 nanometers, and / or the intermediate layer has a thickness between 4 nanometers and 200 nanometers.

[0112] According to one aspect of the present disclosure, an extreme ultraviolet light mask substrate is provided. The extreme ultraviolet light mask substrate includes a multilayer disposed on a substrate, a cover layer disposed on the multilayer, an absorber disposed on the cover layer, a hard mask layer disposed on the absorber, and an intermediate layer disposed on the hard mask layer. The intermediate layer has a higher etching selectivity to the photoresist than to the hard mask layer. In some embodiments, the thickness of the intermediate layer is between 2 nanometers and 200 nanometers. In some embodiments, the intermediate layer includes one or more selected from the group consisting of tantalum oxyboride (TaBO), tantalum boronitride (TaBN), tantalum oxyboronitride (TaBON), palladium (Pd) or nickel (Ni). In some embodiments, the intermediate layer includes one or more selected from the group consisting of silicon oxide (SiO), silicon oxynitride (SiON), silicon nitride (SiN), silicon boronitride (SiBN), silicon borocarbide (SiBC), silicon boron carbide nitride (SiBCN) or polysiloxane. In some embodiments, the intermediate layer includes a top sublayer and a bottom sublayer, wherein the top sublayer includes a silicon-containing material and the bottom sublayer includes a transition metal-containing material, or vice versa. In some embodiments, the intermediate layer includes a plurality of sublayers, wherein at least one sublayer includes a metal-containing material and at least another sublayer includes a silicon-containing material. In some embodiments, the absorber includes tantalum, or one or more selected from the group consisting of tantalum, tantalum borooxide (TaBO), tantalum boronitride (TaBN), tantalum oxyboronnitride (TaBON), palladium (Pd), nickel (Ni), silicon oxide (SiO), silicon oxynitride (SiON), silicon nitride (SiN), silicon boron nitride (SiBN), silicon borocarbide (SiBC), silicon borocarbide nitride (SiBCN), or polysiloxane. In some embodiments, the hard mask layer includes chromium oxynitride (CrON) and has a thickness between 2 nm and 15 nm.

[0113] The foregoing summarizes the features of several embodiments or examples so that those with ordinary knowledge in the art can better understand the various aspects of the present disclosure. Those with ordinary knowledge in the art should understand that they can easily use the present disclosure as a basis for designing or modifying other processes and structures to achieve the same purposes and / or achieve the same benefits as the embodiments or examples introduced herein. Those with ordinary knowledge in the art should also recognize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and they can be variously changed, replaced and modified without departing from the spirit and scope of the present disclosure.

Claims

1. A method for forming a photomask, characterized in that: Include: providing a hard mask layer disposed on top of the absorbent body, a cover layer, and a multilayer layer disposed on a substrate; forming an intermediate layer on the hard mask layer; forming a photoresist layer on the intermediate layer; patterning the photoresist layer; etching the intermediate layer through the patterned photoresist layer; Etching the hard mask layer through the patterned intermediate layer, wherein etching the hard mask layer through the patterned intermediate layer comprises a dry etching process having a first removal rate of the hard mask layer and a second removal rate of the intermediate layer, and a ratio of the first removal rate of the hard mask layer to the second removal rate of the intermediate layer is greater than 5; as well as The absorber is etched through the patterned hard mask layer.

2. The method according to claim 1, characterized in that in, The middle layer includes a plurality of sub-layers, and a thickness of each of the sub-layers is between 2 nanometers and 30 nanometers.

3. The method according to claim 1, characterized in that in, A thickness of the intermediate layer is in a range from 4 nanometers to 200 nanometers.

4. The method according to claim 1, characterized in that: in, The intermediate layer includes one or more selected from the group consisting of tantalum boron oxide (TaBO), tantalum boron nitride (TaBN), tantalum boron oxynitride (TaBON), palladium (Pd) or nickel (Ni).

5. The method according to claim 1, characterized in that in, The intermediate layer includes one or more selected from the group consisting of silicon oxide (SiO), silicon oxynitride (SiON), silicon nitride (SiN), silicon boron nitride (SiBN), silicon borocarbide (SiBC), silicon boron carbide nitride (SiBCN) or polysiloxane.

6. The method according to claim 1, characterized in that The middle layer comprises a top sublayer and a bottom sublayer, wherein the top sublayer comprises a silicon-containing material and the bottom sublayer comprises a transition metal-containing material, or vice versa.

7. The method according to claim 1, characterized in that in, The intermediate layer includes a plurality of sub-layers, wherein at least one of the sub-layers includes a metal-containing material, and at least another of the sub-layers includes a silicon-containing material.

8. The method according to claim 1, characterized in that in, The absorber comprises tantalum, or one or more selected from the group consisting of tantalum, cobalt, chromium, tellurium, platinum, palladium, ruthenium, iridium, nickel and / or alloys thereof.

9. The method according to claim 1, characterized in that: in, The hard mask layer includes a metal layer including chromium or titanium, or one of chromium oxynitride (CrON), tantalum boride (TaB), tantalum oxide (TaO), tantalum oxyboride (TaBO) or tantalum boronitride (TaBN), or a silicon-based compound from one of silicon nitride (SiN) or silicon oxynitride (SiON), and having a thickness between 2 nanometers and 15 nanometers.

10. A method for forming a photomask, characterized in that: Include: forming a multilayer on a substrate; forming an absorbent body on a cover layer disposed on the multiple layers; forming a hard mask layer on the absorbent body; forming an intermediate layer on the hard mask layer, wherein the intermediate layer comprises one or more selected from the group consisting of tantalum boron oxide (TaBO), tantalum boron nitride (TaBN), tantalum boron oxynitride (TaBON), palladium (Pd) or nickel (Ni); forming a photoresist layer on the intermediate layer; patterning the photoresist layer; etching the intermediate layer through the patterned photoresist layer; as well as After etching the intermediate layer, a dry etching process is performed on the hard mask layer. The dry etching process has a first removal rate for the hard mask layer and a second removal rate for the intermediate layer, and a ratio of the first removal rate for the hard mask layer to the second removal rate for the intermediate layer is greater than 5.

11. The method according to claim 10, characterized in that in, The intermediate layer includes a plurality of sub-layers, wherein at least one of the plurality of sub-layers includes a metal-containing material, and at least another sub-layer of the plurality of sub-layers includes a silicon-containing material.

12. The method according to claim 11, characterized in that in, These sub-layers include: a first sub-layer comprising a silicon-containing material; and A second sublayer comprises a transition metal-containing material, wherein the first sublayer and the second sublayer are an alternating pair.

13. The method according to claim 11, characterized in that in, A thickness of each of the sub-layers is between 2 nm and 30 nm, and / or a thickness of the intermediate layer is between 4 nm and 200 nm.

14. The method according to claim 10, characterized in that in, The hard mask layer comprises chromium oxynitride (CrON) and has a thickness between 2 nm and 15 nm, and / or the capping layer comprises ruthenium, and the multilayers comprise a plurality of molybdenum and silicon layer pairs of up to 50 pairs.

15. The method according to claim 10, characterized in that It also includes etching the absorber through the patterned hard mask layer.

16. A method for forming a photomask, characterized in that: Include: forming an intermediate layer on an EUV film stack comprising a substrate, a multilayer on the substrate, a capping layer on the multilayer, an absorber on the capping layer, and a hard mask layer on the absorber; Forming a photoresist layer on the intermediate layer, wherein the intermediate layer comprises one or more selected from the group consisting of silicon oxide (SiO), silicon oxynitride (SiON), silicon nitride (SiN), silicon boron nitride (SiBN), silicon borocarbide (SiBC), silicon boron carbide nitride (SiBCN) or polysiloxane; patterning the photoresist layer; patterning the intermediate layer through the patterned photoresist layer; patterning the hard mask layer through the patterned intermediate layer, wherein patterning the hard mask layer comprises etching the hard mask layer through a dry etching process using the patterned intermediate layer as a mask, wherein the dry etching process has a first removal rate of the hard mask layer and a second removal rate of the intermediate layer, and a ratio of the first removal rate of the hard mask layer to the second removal rate of the intermediate layer is greater than 5; and The absorber is patterned through the patterned hard mask layer.

17. The method according to claim 16, characterized in that in, The intermediate layer includes a top sublayer and a bottom sublayer, wherein the top sublayer includes a silicon-containing material and the bottom sublayer includes a transition metal-containing material.

18. The method according to claim 16, characterized in that in, The intermediate layer includes a plurality of sub-layers, wherein at least one of the sub-layers includes a metal-containing material, and at least another of the sub-layers includes a silicon-containing material.

19. The method according to claim 18, characterized in that in, A thickness of each of the sub-layers is between 2 nm and 30 nm, and / or a thickness of the intermediate layer is between 4 nm and 200 nm.

20. The method according to claim 16, characterized in that in, The absorber comprises tantalum, or one or more selected from the group consisting of tantalum, cobalt, chromium, tellurium, platinum, palladium, ruthenium, iridium, nickel and / or alloys thereof.

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