EUV photomask and method for manufacturing the same

Abstract

The present disclosure relates to EUV photomasks and methods for making the same. In a method for making a reflective mask, a photoresist layer is formed on a mask blank. The mask blank includes a substrate, a reflective multilayer on the substrate, a cap layer on the reflective multilayer, an absorber layer on the cap layer, and a hard mask layer, and the absorber layer is formed of Cr, CrO or CrON. The photoresist layer is patterned, the hard mask layer is patterned by using the patterned photoresist layer, the absorber layer is patterned by using the patterned hard mask layer, and additional elements are introduced into the patterned absorber layer to form a converted absorber layer.

Description

Technical Field

[0001] The present disclosure relates to EUV photomasks and methods of manufacturing the same. Background Art

[0002] Photolithography is one of the key operations in the semiconductor manufacturing process. Photolithography technology includes ultraviolet lithography, deep ultraviolet lithography and extreme ultraviolet lithography (EUVL). Photomask is an important component in photolithography. It is crucial to manufacture EUV photomasks with high contrast including high reflectivity parts and high absorption parts. Summary of the invention

[0003] According to one embodiment of the present disclosure, a reflective mask is provided, comprising: a substrate; a reflective multilayer disposed on the substrate; a cap layer disposed on the reflective multilayer; and an absorber layer disposed on the cap layer, wherein the absorber layer comprises a CrN or CrON layer having a non-uniform nitrogen concentration.

[0004] According to another embodiment of the present disclosure, a reflective mask is provided, comprising: a substrate; a reflective multilayer disposed on the substrate; a cap layer disposed on the reflective multilayer; an intermediate layer disposed on the cap layer; and an absorber layer disposed on the intermediate layer, wherein the absorber layer comprises a CrN or CrON layer having a nitrogen concentration in a surface region of the absorber layer that is higher than a nitrogen concentration in a region deeper than the surface region of the absorber layer.

[0005] According to another embodiment of the present disclosure, a method for manufacturing a reflective mask is provided, the method comprising: forming a photoresist layer on a mask blank, the mask blank comprising a substrate, a reflective multilayer on the substrate, a cap layer on the reflective multilayer, an absorber layer on the cap layer, and a hard mask layer, the absorber layer being formed of Cr, CrO or CrON; patterning the photoresist layer; patterning the hard mask layer by using the patterned photoresist layer; patterning the absorber layer by using the patterned hard mask layer; and introducing additional elements into the patterned absorber layer to form a converted absorber 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 should be emphasized that, in accordance with standard practice in the industry, the various structures are not drawn to scale and are only used for illustrative purposes. In fact, the dimensions of the various structures may be arbitrarily increased or reduced for clarity of discussion.

[0007] Figure 1A , Figure 1B , Figure 1C , Figure 1D and Figure 1EAn EUV photomask blank according to an embodiment of the present disclosure is shown.

[0008] Figure 2A , Figure 2B , Figure 2C , Figure 2D , Figure 2E and Figure 2F A method for manufacturing an EUV photomask according to an embodiment of the present disclosure is schematically shown.

[0009] Figure 3A , Figure 3B , Figure 3C , Figure 3D , Figure 3E and Figure 3F A method for manufacturing an EUV photomask according to an embodiment of the present disclosure is schematically shown.

[0010] Figure 4 A cross-sectional view of an EUV photomask according to an embodiment of the present disclosure is shown.

[0011] Figure 5A , Figure 5B and Figure 5C A cross-sectional view of a multilayer structure of an absorber layer according to another embodiment of the present disclosure is shown.

[0012] Figure 6 A cross-sectional view of an EUV photomask according to an embodiment of the present disclosure is shown.

[0013] Figure 7 A nitrogen concentration profile of an absorber layer of an EUV photomask according to an embodiment of the present disclosure is shown.

[0014] Fig. 8A A flow chart of a method for manufacturing a semiconductor device is shown, and Figure 8B , Figure 8C , Fig.8D and Fig. 8E Sequential manufacturing operations of a method of manufacturing a semiconductor device according to an embodiment of the present disclosure are shown. Specific embodiments

[0015] It should be understood that the following disclosure provides many different embodiments or examples for realizing different features of the present invention. Specific embodiments or examples of components and arrangements are described below to simplify the present disclosure. Of course, these are just examples and are not intended to be limiting. For example, the size of the element is not limited to the disclosed range or value, but may depend on the process conditions and / or required characteristics of the device. In addition, in the following description, forming a first structure on or on a second structure may include an embodiment in which the first and second structures are formed in direct contact, and may also include an embodiment in which an additional structure may be formed between the first and second structures so that the first and second structures may not be in direct contact. For simplicity and clarity, various structures may be arbitrarily drawn in different proportions.

[0016] In addition, spatially related terms may be used herein, for example, "below", "below", "below", "above", "upper", etc., to easily describe the relationship of an element or structure shown in the figure relative to another (some) element or structure. In addition to the orientation shown in the figure, spatially related terms are also intended to include different orientations of the device in use or operation. The device can be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptors used here can also be interpreted accordingly. In addition, the term "consisting of..." can mean "including" 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 unless otherwise specified, does not refer to an element from A, an element from B, and an element from C.

[0017] Embodiments of the present disclosure provide a method for manufacturing an EUV photomask. More specifically, the present disclosure provides a technique for preventing or suppressing damage to a back conductive layer of an EUV photomask.

[0018] EUV lithography (EUVL) uses scanners that use light in the extreme ultraviolet (EUV) region with a wavelength of about 1 nm to about 100 nm (e.g., 13.5 nm). The mask is a key component of the EUVL system. Since optical materials are not transparent to EUV radiation, the EUV photomask 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 3-5%.

[0019] The present disclosure provides an EUV reflective photomask having a low reflective (high absorption) absorber structure.

[0020] Figure 1A and Figure 1B An EUV reflective photomask blank according to an embodiment of the present disclosure is shown. Figure 1A is a plan view (seen from the top), Figure 1B It is a cross-sectional view along the X direction.

[0021] In some embodiments, an EUV photomask having a circuit pattern is formed from an EUV photomask blank 5. The EUV photomask blank 5 includes a substrate 10, a multilayer Mo / Si stack 15 of a plurality of alternating layers of silicon and molybdenum, a cap layer 20, an absorber layer 25, and a hard mask layer 30. Figure 1B As shown, a back conductive layer 45 is formed on the back side of the substrate 10 .

[0022] In some embodiments, the substrate 10 is formed of a low thermal expansion material. In some embodiments, the substrate is a low thermal expansion glass or quartz, such as fused silica glass or fused quartz. In some embodiments, the low thermal expansion glass substrate transmits light of a portion of visible light wavelengths, a portion of infrared wavelengths (near infrared) near the visible spectrum, and a portion of ultraviolet wavelengths. In some embodiments, the low thermal expansion glass substrate absorbs extreme ultraviolet wavelengths and deep ultraviolet wavelengths close to extreme ultraviolet wavelengths. In some embodiments, the size of the substrate 10 is 152 mm×152 mm and the thickness is approximately 20 mm. In other embodiments, the size of the substrate 10 is less than 152 mm×152 mm and is equal to or greater than 148 mm×148 mm. The shape of the substrate 10 is square or rectangular.

[0023] In some embodiments, the width of the functional layers (multilayer Mo / Si stack 15, cap layer 20, absorber layer 25, and hard mask layer 30) above the substrate is less than the width of the substrate 10. In some embodiments, the size of the functional layer is in the range of from about 138 mm×138 mm to 142 mm×142 mm. The shape of the functional layer is square or rectangular.

[0024] In other embodiments, the absorber layer 25 and the hard mask layer 30 have smaller dimensions than the substrate 10, the multilayer Mo / Si stack 15, and the cap layer 20, ranging from about 138 mm×138 mm to 142 mm×142 mm, as shown in FIG. Figure 1C When each functional layer is formed by, for example, sputtering, a smaller size of one or more functional layers can be formed by using a frame-shaped cover having an opening ranging from about 138 mm×138 mm to 142 mm×142 mm. In other embodiments, all layers above the substrate 10 have the same size as the substrate 10.

[0025] In some embodiments, the Mo / Si multilayer stack 15 includes about 30 layers of silicon and molybdenum alternating layers to about 60 layers of silicon and molybdenum alternating layers. In certain embodiments, about 40 to about 50 layers of silicon and molybdenum alternating layers are formed. In some embodiments, for a wavelength of interest, such as 13.5nm, the reflectivity is higher than about 70%. In some embodiments, the silicon layer and the molybdenum layer are formed by chemical vapor deposition (CVD), plasma enhanced CVD (PECVD), atomic layer deposition (ALD), physical vapor deposition (PVD) (sputtering), or any other suitable method of forming a film. Each layer of silicon and molybdenum is about 2nm to about 10nm thick. In some embodiments, the silicon layer and the molybdenum layer have about the same thickness. In other embodiments, the silicon layer and the molybdenum layer have different thicknesses. In some embodiments, the thickness of each silicon layer is about 4nm, and the thickness of each molybdenum layer is about 3nm.

[0026] In other embodiments, the multilayer stack 15 includes alternating layers of molybdenum and beryllium. In some embodiments, the number of layers in the multilayer stack 15 ranges from about 20 to about 100, but any number of layers is allowed as long as sufficient reflectivity is maintained for imaging the target substrate. In some embodiments, the reflectivity is greater than about 70% for wavelengths of interest, such as 13.5 nm. In some embodiments, the multilayer stack 15 includes about 30 to about 60 alternating layers of Mo and Be. In other embodiments of the present disclosure, the multilayer stack 15 includes about 40 to about 50 alternating layers of Mo and Be.

[0027] In some embodiments, the cap layer 20 is disposed on the Mo / Si multilayer stack 15 to prevent oxidation of the multilayer stack 15. In some embodiments, the cap layer 20 is formed of ruthenium, a ruthenium alloy (e.g., RuNb, RuZr, RuZrN, RuRh, RuNbN, RuRhN, RuV, or RuVN), or a ruthenium-based oxide (e.g., RuO2, RuNbO, RiVO, or RuON) with a thickness in the range of about 2 nm to about 10 nm. In some embodiments, the thickness of the cap layer 20 is in the range of from about 2 nm to about 5 nm. In some embodiments, the thickness of the cap layer 20 is 3.5 nm ± 10%. In some embodiments, the cap layer 20 is formed by chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, physical vapor deposition (e.g., sputtering), or any other suitable method of forming a film. In other embodiments, a Si layer is used as the cap layer 20.

[0028] The absorber layer 25 is disposed on the cap layer 20. In an embodiment of the present disclosure, the absorber layer 25 includes a Cr-based material, such as Cr, CrO and / or CrON, with a nitrogen content of about 16 atomic % to about 40 atomic %, and an oxygen content of greater than 0 atomic % to about 30 atomic %. In some embodiments, the absorber layer 25 has a multilayer structure of C, CrO, or CrON. In some embodiments, the thickness of the absorber layer 25 is in a range from about 20 nm to about 50 nm, and in other embodiments, in a range from about 35 nm to about 46 nm. In some embodiments, when the Cr-based material includes oxygen, the amount of oxygen is in a range from about 5 atomic % to about 30 atomic %, and in other embodiments, in a range from about 10 atomic % to about 25 atomic %. In some embodiments, the absorber layer 25 also includes one or more elements of Co, Te, Hf and / or Ni.

[0029] In some embodiments, an anti-reflection layer (not shown) is optionally disposed on the absorber layer 25. In some embodiments, the anti-reflection layer is formed of silicon oxide and has a thickness of about 2 nm to about 10 nm. In other embodiments, a TaBO layer having a thickness ranging from about 12 nm to about 18 nm is used as the anti-reflection layer. In some embodiments, the thickness of the anti-reflection layer is about 3 nm to 6 nm. 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 method of forming a film.

[0030] In some embodiments, the hard mask layer 30 is disposed on the absorber layer 25. In some embodiments, the hard mask layer 30 is formed on the anti-reflective layer. In some embodiments, the hard mask layer 30 is formed of a Ta-based material, for example, TaB, TaO, TaBO, or TaBN. In other embodiments, the hard mask layer 30 is formed of silicon, a silicon-based compound (for example, SiN or SiON), ruthenium, or a ruthenium-based compound (Ru or RuB). In some embodiments, the hard mask layer 30 has a thickness of about 4 nm to about 20 nm. In some embodiments, the hard mask layer 30 is formed by chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, physical vapor deposition, or any other suitable method of forming a film.

[0031] In some embodiments, the back conductive layer 45 is disposed on a second main surface of the substrate 10, which is opposite to the first main surface of the substrate 10 on which the Mo / Si multilayer stack 15 is formed. In some embodiments, the back conductive layer 45 is formed of TaB (tantalum boride) or other Ta-based conductive materials. In some embodiments, tantalum boride is crystalline. Crystalline tantalum boride includes TaB, Ta5B6, Ta3B4 and TaB2. In other embodiments, tantalum boride is polycrystalline or amorphous. In other embodiments, the back conductive layer 45 is formed of a Cr-based conductive material (CrN or CrON). In some embodiments, the sheet resistance of the back conductive layer 45 is equal to or less than 20Ω / □. In some embodiments, the sheet resistance of the back conductive layer 45 is equal to or greater than 0.1Ω / □. In some embodiments, the surface roughness Ra of the back conductive layer 45 is equal to or less than 0.25nm. In some embodiments, the surface roughness Ra of the back conductive layer 45 is equal to or greater than 0.05nm. In addition, in some embodiments, the flatness of the back conductive layer 45 (within the EUV photomask) is equal to or less than 50nm. In some embodiments, the flatness of the back conductive layer 45 is greater than 1nm. In some embodiments, the thickness of the back conductive layer 45 is in the range from about 50nm to about 400nm. In other embodiments, the back conductive layer 45 has a thickness of about 50nm to about 100nm. In certain embodiments, the thickness is in the range from about 65nm to about 75nm. In some embodiments, the back conductive layer 45 is formed by atmospheric chemical vapor deposition (CVD), low pressure CVD, plasma enhanced CVD, laser enhanced CVD, atomic layer deposition (ALD), 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 method of forming a film. In some embodiments, in the case of CVD, the source gas includes TaCl5 and BCl3.

[0032] In some embodiments, such as Figure 1D As shown, an additional (intermediate) layer 22 is formed between the cap layer 20 and the absorber layer 25. In some embodiments, the additional layer 22 is used to protect the cap layer. In some embodiments, the additional layer 22 includes a Ta-based material (e.g., TaB, TaO, TaBO, or TaBN), silicon, a silicon-based compound (e.g., silicon oxide, SiN, SiON, or MoSi), ruthenium, or a ruthenium-based compound (Ru or RuB). In some embodiments, the thickness of the additional layer 22 is about 2 nm to about 20 nm. In some embodiments, the additional layer 22 is formed by chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, physical vapor deposition, or any other suitable method of forming a film. In some embodiments, the additional layer 22 is used as an etch stop layer during the patterning operation of the absorber layer.

[0033] In other embodiments, the additional layer 22 is a photocatalytic layer that can catalyze hydrocarbon residues formed on the photomask into CO2 and / or H2O using EUV radiation. Thus, in-situ self-cleaning of the mask surface is performed. In some embodiments, in the EUV scanner system, oxygen and hydrogen are injected into the EUV chamber to maintain the chamber pressure (e.g., at about 2 Pa). The chamber background gas can be a source of oxygen. In addition to the photocatalytic function, the photocatalytic layer is also designed to have sufficient durability and resistance to various chemicals and various chemical processes (e.g., cleaning and etching). In some examples, ozonated water used to manufacture EUV reflective masks in subsequent processes can damage the cap layer 20 formed of Ru and cause a significant decrease in EUV reflectivity. It is further observed that after Ru oxidation, Ru oxide is easily etched away by an etchant such as C12 or CF4 gas. In some embodiments, the photocatalytic layer includes one or more of titanium oxide (TiO2), tin oxide (SnO), zinc oxide (ZnO), and cadmium sulfide (CdS). In some embodiments, the thickness of the photocatalytic layer 22 is in a range from about 2 nm to about 10 nm, and in other embodiments, in a range from about 3 nm to about 7 nm. When the thickness is too thin, the photocatalytic layer may not be sufficient to serve as an etch stop layer. When the thickness is too large, the photocatalytic layer may absorb EUV radiation.

[0034] In some embodiments, Figure 1E As shown, a substrate protection layer 12 is formed between the substrate 10 and the multilayer stack 15. In some embodiments, the substrate protection layer 12 is formed of Ru or a Ru compound, for example, RuO, RuNb, RuNbO, RuZr, and RuZrO. In some embodiments, the substrate protection layer 12 is formed of the same or different material as the cap layer 20. In some embodiments, the thickness of the substrate protection layer 12 is in a range from about 2 nm to about 10 nm.

[0035] Figure 2A-2F and Figure 3A-Figure 3F The method for manufacturing an EUV photomask for extreme ultraviolet lithography (EUVL) is schematically shown. It should be understood that in Figure 2A-Figure 3F Additional operations are provided before, during, and after the illustrated processes, and some of the operations described below may be replaced or eliminated for additional embodiments of the method. The order of these operations / processes may be interchangeable.

[0036] In the manufacture of the EUV photomask, a first photoresist layer 35 is formed on the hard mask layer 30 of the EUV photomask blank. Figure 2A As shown, the photoresist layer 35 is then selectively exposed to actinic radiation EB, such as Figure 2BIn some embodiments, before forming the first photoresist layer 35, the EUV photomask blank is inspected. The selectively exposed first photoresist layer 35 is developed to form a pattern 40 in the first photoresist layer 35, as shown in FIG. Figure 2C In some embodiments, the actinic radiation EB is an electron beam or an ion beam. In some embodiments, pattern 40 corresponds to the pattern of semiconductor device features that an EUV photomask will be used to form in a subsequent operation.

[0037] Next, the pattern 40 in the first photoresist layer 35 is extended into the hard mask layer 30, thereby forming a pattern 41 in the hard mask layer 30, exposing portions of the absorber layer 25, such as Figure 2D In some embodiments, a pattern 41 extending into the hard mask layer 30 is formed by etching using a suitable wet or dry etchant that is selective to the absorber layer 25. After forming the pattern 41 in the hard mask layer 30, the first photoresist layer 35 is removed using a photoresist stripper to expose the upper surface of the hard mask layer 30, as shown in FIG. Figure 2E shown.

[0038] Then, the pattern 41 in the hard mask layer 30 is extended into the absorber layer 25, thereby forming a pattern 42 in the absorber layer 25, exposing portions of the cap layer 20, such as Figure 2F As shown, the hard mask layer 30 is then removed, as shown in FIG. Figure 3A In some embodiments, the pattern 42 extending into the absorber layer 25 is formed by etching using a suitable wet or dry etchant that is selective to the absorber layer 25. In some embodiments, plasma dry etching is used.

[0039] like Figure 3B As shown, a second photoresist layer 50 is formed on the absorber layer 25, filling the pattern 42 in the absorber layer 25. The second photoresist layer 50 is selectively exposed to actinic radiation, such as an electron beam, an ion beam, or UV radiation. The selectively exposed second photoresist layer 50 is developed to form a pattern 55 in the second photoresist layer 50, as shown in FIG. Figure 3B As shown. Pattern 55 corresponds to a black edge around the circuit pattern. The black edge is a frame-shaped area created by removing all the multiple layers on the EUV photomask in the area around the circuit pattern area. The frame-shaped area is created to prevent exposure of adjacent fields when the EUV photomask is printed on the wafer. In some embodiments, the width of the black edge is in the range from about 1 mm to about 5 mm.

[0040] Next, the pattern 55 in the second photoresist layer 50 is extended into the absorber layer 25, the cap layer 20 and the Mo / Si multilayer stack 15 to form a pattern 57 in the absorber layer 25, the cap layer 20 and the Mo / Si multilayer stack 15 (see Figure 3D ), exposing multiple portions of the substrate 10, such as Figure 3C In some embodiments, pattern 57 is formed by etching using one or more suitable wet or dry etchants that are selective to each layer being etched. In some embodiments, plasma dry etching is used.

[0041] Then, the second photoresist layer 50 is removed using a suitable photoresist stripper to expose the upper surface of the absorber layer 25, such as Figure 3D In some embodiments of the present disclosure, the absorber layer 25, the cap layer 20, and the black edge pattern 57 in the Mo / Si multilayer stack 15 define a black edge of the photomask.

[0042] Next, if Figure 3E As shown, one or more ion implantation operations are performed to change the composition of the patterned absorber layer 25 into the converted absorber layer 60. In some embodiments, ions ION, such as nitrogen ions, are implanted into the patterned absorber layer 25. In some embodiments, the acceleration voltage of the nitrogen ion implantation is in the range of from about 0.1 keV to about 5 keV, and in other embodiments, in the range of from about 0.5 keV to 2 keV. When the acceleration voltage is too high, the ions may pass through the absorber layer and be mainly implanted into the cap layer or the multilayer stack, while when the acceleration voltage is too low, only the upper portion of the absorber layer will be implanted with ions. In some embodiments, the dose is in the range of from about 5×10 15 ion / cm 2 Up to 1×10 17 ion / cm 2 In other embodiments, the range is from about 1×10 16 ion / cm 2 Up to 4×10 16 ion / cm 2 When the dose is too low, the nitrogen concentration in the converted absorber layer 60 is insufficient to obtain a high EUV absorption coefficient (see below), while if the dose is too high, the mechanical strength of the converted absorber layer may be reduced. In some embodiments, the ion implantation is performed at room temperature (25° C.) with a concentration of about 1×10 -9 Pa to 6×10 -8 It is performed under a pressure of Pa.

[0043] In some embodiments, when the absorber layer 25 is formed of Cr (Cr content is greater than 90 atomic %), the absorber layer 25 is converted into CrN having a nitrogen content in the range of from about 5 atomic % to about 16 atomic %. In some embodiments, when the absorber layer 25 is formed of CrO, the absorber layer 25 is converted into CrON having a nitrogen content in the range of from about 5 atomic % to about 16 atomic %, and an oxygen content in the range of from greater than 0 atomic % to about 5 atomic %. In some embodiments, the CrON layer is a nitrogen-rich (more than oxygen) CrON layer. In some embodiments, when the absorber layer 25 is formed of CrON, the absorber layer 25 is converted into nitrogen-rich CrON (more than oxygen), having a nitrogen content in the range of from about 5 atomic % to about 20 atomic %, and an oxygen content in the range of from greater than 0 atomic % to 4 atomic %.

[0044] In other embodiments, nitrogen is introduced into the patterned absorber layer 25 using plasma PL to form a converted absorber layer 60, such as Figure 3F As shown. In some embodiments, the plasma PL is a nitrogen plasma generated by N2 gas and / or NH3 gas. In some embodiments, the plasma is an RF plasma, an ICP (inductively coupled plasma) or a microwave generated plasma (e.g., an ECR plasma). In some embodiments, the source power is in the range of from about 200W to about 600W, and in other embodiments, in the range of from about 300W to 500W. In some embodiments, the bias power is in the range of from about 1W to about 50W, and in other embodiments, in the range of from about 5W to 10W. In some embodiments, the flow rate of N2 gas is in the range of from about 100sccm to 1000sccm, and in other embodiments, in the range of from about 200sccm to 500sccm. In some embodiments, the partial pressure of N2 is in the range of from about 1mTorr to 50mTorr, and in other embodiments, in the range of from about 2mTorr to about 10mTorr. In some embodiments, both ion implantation and plasma treatment convert the patterned absorber layer 25 into a converted absorber layer 60.

[0045] Generally, Cr-based materials (CrN, CrON, or CrO) have a high EUV absorption (extinction) coefficient k. For example, the k value of CrN is 0.0387, which is higher than the k value of TaBN (0.031) and the k value of TaBO (0.027). Therefore, the thickness of the absorber layer can be reduced (for example, from 70nm of TaBN to 46nm of CrN), which can suppress the three-dimensional effect of the patterned absorber layer. However, due to the low etching rate of the CrN layer or the nitrogen-rich CrON layer, it is difficult to etch. Therefore, directly patterning the CrN layer may result in a poor pattern profile, thereby affecting the resolution of EUV lithography. In the present embodiment, the Cr, CrO, or CrON (low nitrogen concentration) layer is subjected to an etching operation (see Figure 2F ), and then converted into CrN or nitrogen-rich CrON layer. Thus, a good pattern profile with higher etching rate and higher EUV absorption coefficient can be obtained.

[0046] In other embodiments, instead of or in addition to introducing nitrogen as described above, one or more of Li, Be, B, C, or Si is introduced into the patterned absorber layer 25 by, for example, an ion implantation process or a plasma process. The conditions for the ion implantation and / or plasma process of Li, Be, B, C, and / or Si are the same or similar to the conditions for nitrogen. Thus, the converted absorber layer 60 includes a Cr, CrO, CrN, or CrON layer containing one or more of Li, Be, B, C, or Si. In some embodiments, the amount of Li, Be, B, C, and / or Si is in the range from about 5 atomic % to 24 atomic %. In some embodiments, these elements are not included in the absorber layer 25 of the mask blank 5. In some embodiments, the absorber layer 60 is one or more of CrLi, CrBe, CrB, CrC, or CrSi having a k value greater than 0.03.

[0047] In other embodiments, a conversion process (ion implantation and / or plasma process as described above) is performed after patterning the absorber layer and removing the hard mask layer and before forming the black edge pattern 57 .

[0048] In some embodiments, after the conversion process of the patterned absorber layer, an annealing operation is performed. In some embodiments, the annealing temperature is in a range from about 60° C. to about 120° C. In addition, the photomask is cleaned, inspected, and repaired as needed to provide a finished photomask.

[0049] Figure 4 1 shows a cross-sectional view of a finished EUV photomask according to an embodiment of the present disclosure. Figure 4The EUV photomask with the circuit pattern 42 shown includes a substrate 10, a multilayer Mo / Si stack 15 of a plurality of alternating layers of silicon and molybdenum, a cap layer 20, and a patterned absorber layer 60. In addition, a black edge pattern 57 is formed in the absorber layer 60, the cap layer 20, and the multilayer stack 15, and a back conductive layer 45 is formed on the back side of the substrate 10. In some embodiments, the patterned absorber layer 60 includes a CrN layer, a nitrogen-rich CrON layer, and / or a Cr, CrN, CrO, or CrON layer doped with one or more of Li, Be, B, C, or Si. In some embodiments, when one or more of Li, Be, B, C, or Si is included, the absorber layer is substantially free of nitrogen and / or oxygen (less than about 1 atomic %).

[0050] In some embodiments, the absorber layer is a single layer of the above-mentioned Cr-based material, or includes multiple layers, one or more of which are the above-mentioned Cr-based materials. In some embodiments, the thickness of the absorber layer 60 is in the range from about 20 nm to about 50 nm, and in other embodiments, in the range from about 35 nm to about 46 nm. In some embodiments, at the bottom of the opening of the absorber layer 60, the cap layer 20 contains more one or more of N, Li, Be, B, C, or Si than other parts of the photomask (e.g., under the absorber layer 60 or at the bottom of the cap layer near the multilayer stack 15).

[0051] Figure 5A , Figure 5B and Figure 5C FIG. 4 shows a cross-sectional view of a multilayer structure of an absorber layer according to another embodiment of the present disclosure. It should be understood that Figures 5A-5C Additional operations are provided before, during and after the process shown, and for other embodiments of the method, some of the operations described below can be replaced or eliminated. The order of these operations / processes can be interchangeable. In the following embodiments, the materials, configurations, processes and / or sizes explained for the aforementioned embodiments can be adopted, so detailed descriptions thereof can be omitted. Figure 5A , Figure 5B and Figure 5C The embodiment is used for Figure 1D The mask embryo is shown. Figure 5A shows the structure after the hard mask layer 30 is patterned, similar to Figure 2E Then, by using the patterned hard mask layer 25, the absorber layer is patterned (etched), as shown in FIG. Figure 5B In some embodiments, when the additional layer 22 is formed of the same or similar material as the hard mask layer 30, the etching substantially stops at the additional layer 22. Then, as shown in FIG. Figure 5CAs shown, the hard mask layer 30 is removed together with a portion of the additional layer 22 at the bottom of the opening pattern of the absorber layer 25. In some embodiments, the etching is wet etching and / or dry etching.

[0052] In other embodiments, when the additional layer 22 is formed of a different material than the hard mask layer 30, the etching substantially stops at the additional layer 22 or also etches the additional layer 22. In some embodiments, when the etching substantially stops at the additional layer 22, the additional layer 22 is subsequently patterned or remains unetched.

[0053] Figure 6 1 shows a cross-sectional view of a finished photomask according to an embodiment of the present disclosure. Figure 6 The EUV photomask with the circuit pattern 42 shown includes a substrate 10, a multilayer Mo / Si stack 15 of multiple alternating layers of silicon and molybdenum, a cap layer 20, a patterned additional layer 22, and a patterned absorber layer 60. In addition, a black edge pattern 57 is formed in the absorber layer 60, the cap layer 20, and the multilayer stack 15, and a back conductive layer 45 is formed on the back side of the substrate 10. In some embodiments, the patterned absorber layer 60 includes a CrN layer, a nitrogen-rich CrON layer, and / or a Cr, CrN, CrO, or CrON layer doped with one or more of Li, Be, B, C, or Si. In some embodiments, when one or more of Li, Be, B, C, or Si is included, the absorber layer is substantially free of nitrogen and / or oxygen (less than about 1 atomic %). In some embodiments, the absorber layer is a single layer of the above-mentioned Cr-based material, or includes multiple layers, one or more of which is the above-mentioned Cr-based material. In some embodiments, the thickness of the absorber layer 60 is in a range from about 20 nm to about 50 nm, and in other embodiments, in a range from about 35 nm to about 46 nm. In some embodiments, at the bottom of the openings for the absorber layer 60, the cap layer 20 contains more one or more of N, Li, Be, B, C, or Si than in other portions of the photomask (e.g., under the absorber layer 60 or at the bottom of the cap layer near the multilayer stack 15). If the additional layer 22 remains at the bottom of the openings for the absorber layer 60, then at the bottom of these openings, the additional layer 22 contains more one or more of N, Li, Be, B, C, or Si than in other portions of the photomask (e.g., under the absorber layer 60 or at the bottom of the additional layer 22 near the cap layer 20).

[0054] Figure 760 is a graph showing a nitrogen concentration profile of an absorber layer of an EUV photomask according to an embodiment of the present disclosure. As described above, nitrogen (or other elements Li, Be, B, C and / or Si) is introduced after the absorber layer 25 is patterned according to an external pattern. Therefore, in some embodiments, nitrogen (or Li, Be, B, C and / or Si) does not have a uniform concentration profile (distribution) within the absorption pattern 60.

[0055] In some embodiments, along the horizontal direction (through the center (center of gravity) of the absorption pattern 60), the concentration of nitrogen (or Li, Be, B, C and / or Si) decreases from one side to a minimum value, and then increases to the opposite side. In some embodiments, the ratio of the maximum concentration to the minimum concentration is in a range from about 1.1 to about 5.0.

[0056] In some embodiments, along the vertical direction (through the center of the absorption pattern 60), the concentration of nitrogen (or Li, Be, B, C and / or Si) increases from the bottom of the absorption pattern 60 to the top of the absorption pattern 60. The ratio of the maximum concentration to the minimum concentration is in the range from about 1.1 to about 10.0. In some embodiments, the ratio of the highest concentration to the lowest concentration in the entire absorption pattern 60 is in the range from about 1.1 to about 10.0.

[0057] In some embodiments, near the interface between the absorber layer 60 and the cap layer 20, there is still an unconverted absorption region 25R (eg, 1 nm 3 -100nm 3 ), the region is substantially free of later introduced elements. In some embodiments, the volume of the region is at least 1 nm 3 , 2nm 3 , 5nm 3 or 10nm 3 .

[0058] Fig. 8A The process of a method for manufacturing a semiconductor device is shown. Figure 8B , Figure 8C , Fig.8D and Fig. 8E Sequential manufacturing operations of a method for manufacturing a semiconductor device according to an embodiment of the present disclosure are shown. A semiconductor substrate or other suitable substrate is provided, which is to be patterned to form an integrated circuit thereon. In some embodiments, the semiconductor substrate includes silicon. Alternatively or additionally, the semiconductor substrate includes germanium, silicon germanium, or other suitable semiconductor material, such as a III-V semiconductor material. Fig. 8AIn S101, a target layer to be patterned is formed on a semiconductor substrate. In some embodiments, the target layer is a semiconductor substrate. In some embodiments, the target layer includes a conductive layer such as a metallization layer or a polysilicon layer, a dielectric layer such as silicon oxide, silicon nitride, SiON, SiOC, SiOCN, SiCN, hafnium oxide, or aluminum oxide, or a semiconductor layer such as an epitaxially formed semiconductor layer. In some embodiments, the target layer is formed on an underlying structure such as an isolation structure, a transistor, or a wiring. Fig. 8A At S102, a photoresist layer is formed on the target layer, such as Figure 8B As shown. In the subsequent photolithography exposure process, the photoresist layer is sensitive to radiation from the exposure source. In this embodiment, the photoresist layer is sensitive to EUV light used in the photolithography exposure process. The photoresist layer can be formed on the target layer by spin coating or other suitable techniques. The coated photoresist layer can be further baked to drive out the solvent in the photoresist layer. Fig. 8A In S103, the photoresist layer is patterned using the EUV reflective mask as described above, such as Figure 8B As shown. Patterning the photoresist layer includes performing a photolithography exposure process using an EUV exposure system using an EUV mask. In the exposure process, the integrated circuit (IC) design pattern defined on the EUV mask is imaged onto the photoresist layer to form a latent pattern thereon. Patterning the photoresist layer also includes developing the exposed photoresist layer to form a patterned photoresist layer having one or more openings. In an embodiment where the photoresist layer is a positive photoresist layer, the exposed portion of the photoresist layer is removed in the development process. Patterning the photoresist layer may also include other process steps, such as various baking steps at different stages. For example, a post-exposure baking (PEB) process may be implemented after the photolithography exposure process and before the development process.

[0059] exist Fig. 8A In S104, the target layer is patterned using the patterned photoresist layer as an etching mask, such as Fig.8D In some embodiments, patterning the target layer includes applying an etching process to the target layer using the patterned photoresist layer as an etching mask. Portions of the target layer exposed within the openings of the patterned photoresist layer are etched, while the remaining portions are not etched. In addition, the patterned photoresist layer can be removed by wet stripping or plasma ashing, such as Fig. 8E shown.

[0060] In the present disclosure, the Cr, CrO or CrON (low nitrogen concentration) layer is etched and then converted into a CrN or nitrogen-rich CrON layer, so that a good pattern profile with a high etching rate and a high EUV absorption coefficient can be obtained. In addition, since the CrN or nitrogen-rich CrON layer has a high EUV absorption coefficient, the thickness of the absorber layer can be reduced, which in turn suppresses the three-dimensional effect in EUV lithography.

[0061] It should be understood that not all advantages have been discussed herein, that no particular advantage is required of all embodiments or examples, and that other embodiments or examples may have different advantages.

[0062] According to one aspect of the present application, a reflective mask includes a substrate, a reflective multilayer disposed on the substrate, a cap layer disposed on the reflective multilayer, and an absorber layer disposed on the cap layer. The absorber layer includes a CrN or CrON layer having a non-uniform nitrogen concentration. In one or more of the foregoing and following embodiments, the thickness of the absorber layer is in the range of 20nm to 50nm. In one or more of the foregoing and following embodiments, the absorber layer includes one or more of Li, Be, B, C or Si. In one or more of the foregoing and following embodiments, the absorber layer includes one or more of Li, Be or C. In one or more of the foregoing and following embodiments, the absorber layer includes a CrON layer in which the nitrogen content is greater than the oxygen content. In one or more of the foregoing and following embodiments, in a plan view, the size of the periphery of the absorber layer is smaller than the size of the periphery of the substrate. In one or more of the foregoing and following embodiments, in a plan view, the size of the periphery of the absorber layer is in the range of 138mm×138mm to 142mm×142mm, and in a plan view, the size of the periphery of the substrate is in the range of 148mm×148mm to 152mm×152mm. In one or more of the foregoing and following embodiments, the absorber layer includes a region formed of CrO or Cr.

[0063] According to another aspect of the present disclosure, a reflective mask includes a substrate, a reflective multilayer disposed on the substrate, a cap layer disposed on the reflective multilayer, an intermediate layer disposed on the cap layer, and an absorber layer disposed on the intermediate layer. The absorber layer includes a CrN or CrON layer having a nitrogen concentration in a surface region of the absorber layer that is higher than that in the interior of the absorber layer. In one or more of the foregoing and following embodiments, the thickness of the absorber layer is equal to or less than 45 nm. In one or more of the foregoing and following embodiments, the intermediate layer includes at least one of the following: TaB, TaO, TaBO, TaBN, silicon, a silicon-based compound, ruthenium, or a ruthenium-based compound. In one or more of the foregoing and following embodiments, the intermediate layer includes at least one of the following: titanium oxide (TiO2), tin oxide (SnO), zinc oxide (ZnO), or cadmium sulfide (CdS). In one or more of the foregoing and following embodiments, the absorber layer includes a CrON layer in which the nitrogen content is greater than the oxygen content. In one or more of the foregoing and following embodiments, the size of the periphery of the absorber layer in a plan view is in the range of 138 mm×138 mm to 142 mm×142 mm, and the size of the periphery of the reflective multilayer in a plan view is in the range of 148 mm×148 mm to 152 mm×152 mm. In one or more of the foregoing and following embodiments, the absorber layer includes a region formed of CrO or Cr, the volume of the region being 1 nm 3 -10nm 3 In one or more of the foregoing and following embodiments, the volume of the region is at least 1 nm 3 .

[0064] According to another aspect of the present disclosure, an EUV reflective mask includes a substrate, a reflective multilayer disposed on the substrate, a cap layer disposed on the reflective multilayer, and an absorber layer disposed on the cap layer. The absorber layer includes Cr and at least one of Li, Be, B, C, or Si. In one or more of the foregoing and following embodiments, one or more of Li, Be, B, C, or Si has an uneven distribution in the absorber layer. In one or more of the foregoing and following embodiments, the absorber layer also includes nitrogen. In one or more of the foregoing and following embodiments, the distribution of nitrogen in the absorber layer is uneven.

[0065] According to another aspect of the present disclosure, in a method for manufacturing a reflective mask, a photoresist layer is formed on a mask blank. The mask blank includes a substrate, a reflective multilayer on the substrate, a cap layer on the reflective multilayer, an absorber layer on the cap layer, and a hard mask layer, and the absorber layer is formed of Cr, CrO or CrON. The photoresist layer is patterned, the hard mask layer is patterned by using the patterned photoresist layer, the absorber layer is patterned by using the patterned hard mask layer, and ions are introduced into the patterned absorber layer by an ion implantation operation to form a converted absorber layer. In one or more of the foregoing and following embodiments, the ions are nitrogen ions. In one or more of the foregoing and following embodiments, after the absorber layer is patterned, the hard mask layer is removed, and after the hard mask layer is removed, the ions are introduced. In one or more of the foregoing and following embodiments, ions are also introduced into a portion of the cap layer. In one or more of the foregoing and following embodiments, after the ions are introduced, an annealing operation is performed. In one or more of the foregoing and following embodiments, the absorber layer of the mask blank includes Cr in an amount of 95 atomic % or more. In one or more of the foregoing and following embodiments, the accelerating voltage of the ion implantation operation is in the range of from 0.1 keV to 5 keV. In one or more of the foregoing and following embodiments, the dose of the ion implantation operation is in the range of from 5×10 15 ion / cm 2 Up to 1×10 17 ion / cm 2 In one or more of the foregoing and following embodiments, the mask blank further comprises an intermediate layer between the cap layer and the absorber layer. In one or more of the foregoing and following embodiments, the intermediate layer is formed of the same material as the hard mask layer. In one or more of the foregoing and following embodiments, the intermediate layer serves as an etch stop layer when patterning the absorber layer. In one or more of the foregoing and following embodiments, the ions are ions of one or more elements selected from the group consisting of Li, Be, B, C and Si. In one or more of the foregoing and following embodiments, the absorber layer of the mask blank comprises Cr in an amount of 95 atomic % or more.

[0066] According to another aspect of the present disclosure, in a method for manufacturing a reflective mask, a photoresist layer is formed on a mask blank. The mask blank includes a substrate, a reflective multilayer on the substrate, a cap layer on the reflective multilayer, an absorber layer on the cap layer, and a hard mask layer, and the absorber layer includes Cr. The photoresist layer is patterned, the hard mask layer is patterned by using the patterned photoresist layer, the absorber layer is patterned by using the patterned hard mask layer, and nitrogen is introduced into the patterned absorber layer by a plasma process to form a converted absorber layer. In one or more of the foregoing and following embodiments, the absorber layer of the mask blank includes Cr at a content of 95 atomic % or more. In one or more of the foregoing and following embodiments, the absorber layer of the mask blank is formed of CrO or CrON.

[0067] According to another aspect of the present disclosure, in a method for manufacturing a reflective mask, a photoresist layer is formed on a mask blank. The mask blank includes a substrate, a reflective multilayer on the substrate, a cap layer on the reflective multilayer, an absorber layer on the cap layer, and a hard mask layer, and the absorber layer is formed of Cr, CrO or CrON. The photoresist layer is patterned, the hard mask layer is patterned by using the patterned photoresist layer, the absorber layer is patterned by using the patterned hard mask layer, and an additional element is introduced into the patterned absorber layer to form a converted absorber layer. In one or more of the foregoing and following embodiments, the additional element is nitrogen. In one or more of the foregoing and following embodiments, the nitrogen is introduced by an ion implantation operation. In one or more of the foregoing and following embodiments, the nitrogen is introduced by a plasma process.

[0068] The foregoing summarizes the features of several embodiments or examples so that those skilled in the art can better understand the various aspects of the present disclosure. Those skilled in the art will appreciate 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 advantages as the embodiments or examples introduced herein. Those skilled in the art will also appreciate that these equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they can make various changes, substitutions, and modifications without departing from the spirit and scope of the present disclosure.

[0069] Example 1. A reflective mask comprising: a substrate; a reflective multilayer disposed on the substrate; a cap layer disposed on the reflective multilayer; and an absorber layer disposed on the cap layer, wherein the absorber layer comprises a CrN or CrON layer having a non-uniform nitrogen concentration.

[0070] Example 2. The reflective mask of Example 1, wherein the absorber layer has a thickness in a range from 20 nm to 50 nm.

[0071] Example 3. The reflective mask of Example 1, wherein the absorber layer comprises one or more of: Li, Be, B, C, or Si.

[0072] Example 4. The reflective mask of Example 1, wherein the absorber layer comprises one or more of: Li, Be, or C.

[0073] Example 5. The reflective mask of Example 1, wherein the absorber layer comprises a CrON layer in which a nitrogen content is greater than an oxygen content.

[0074] Example 6. The reflective mask of Example 1, wherein, in a plan view, a size of an outer periphery of the absorber layer is smaller than a size of an outer periphery of the substrate.

[0075] Example 7. A reflective mask according to Example 6, wherein, in a plan view, the size of the periphery of the absorber layer is in the range from 138 mm×138 mm to 142 mm×142 mm, and in a plan view, the size of the periphery of the substrate is in the range from 148 mm×148 mm to 152 mm×152 mm.

[0076] Example 8. The reflective mask of Example 1, wherein the absorber layer includes a region formed of CrO or Cr.

[0077] Example 9. A reflective mask comprising: a substrate; a reflective multilayer disposed on the substrate; a cap layer disposed on the reflective multilayer; an intermediate layer disposed on the cap layer; and an absorber layer disposed on the intermediate layer, wherein the absorber layer comprises a CrN or CrON layer having a nitrogen concentration in a surface region of the absorber layer that is higher than a nitrogen concentration in a region deeper than the surface region of the absorber layer.

[0078] Example 10. The reflective mask of Example 9, wherein the thickness of the absorber layer is equal to or less than 45 nm.

[0079] Example 11. The reflective mask of Example 9, wherein the intermediate layer comprises at least one of TaB, TaO, TaBO or TaBN, silicon, a silicon-based compound, ruthenium or a ruthenium-based compound.

[0080] Example 12. The reflective mask according to Example 9, wherein the intermediate layer comprises at least one of the following: titanium oxide TiO2, tin oxide SnO, zinc oxide ZnO or cadmium sulfide CdS.

[0081] Example 13. The reflective mask of Example 9, wherein the absorber layer comprises a CrON layer in which the nitrogen content is greater than the oxygen content.

[0082] Example 14. A reflective mask according to Example 9, wherein, in a plan view, the dimensions of the periphery of the absorber layer are in the range from 138 mm×138 mm to 142 mm×142 mm, and in a plan view, the dimensions of the periphery of the reflective multilayer are in the range from 148 mm×148 mm to 152 mm×152 mm.

[0083] Example 15. The reflective mask of Example 9, wherein the absorber layer comprises a region formed of CrO or Cr, the volume of the region being 1 nm 3 -10nm 3 .

[0084] Example 16. The reflective mask of Example 15, wherein the region has a thickness of at least 1 nm. 3 volume.

[0085] Example 17. A method for manufacturing a reflective mask, the method comprising: forming a photoresist layer on a mask blank, the mask blank comprising a substrate, a reflective multilayer on the substrate, a cap layer on the reflective multilayer, an absorber layer on the cap layer, and a hard mask layer, the absorber layer being formed of Cr, CrO or CrON; patterning the photoresist layer; patterning the hard mask layer by using the patterned photoresist layer; patterning the absorber layer by using the patterned hard mask layer; and introducing additional elements into the patterned absorber layer to form a converted absorber layer.

[0086] Example 18. The method of Example 17, wherein the additional element is nitrogen.

[0087] Example 19. The method of Example 18, wherein the nitrogen is introduced by an ion implantation operation.

[0088] Example 20. The method of Example 18, wherein the nitrogen is introduced via a plasma process.

Claims

1. A reflective mask, comprising: substrate; a reflective multilayer disposed on the substrate; A cap layer, disposed on the reflective multilayer; as well as an absorbent layer, disposed on the cap layer, The absorber layer includes a CrN or CrON layer, and the CrN or CrON layer has a non-uniform nitrogen concentration along a horizontal direction parallel to a surface of the substrate.

2. The reflective mask according to claim 1, wherein: The thickness of the absorber layer is in the range from 20 nm to 50 nm.

3. The reflective mask according to claim 1, wherein: The absorber layer includes one or more of the following: Li, Be, B, C or Si.

4. The reflective mask according to claim 1, wherein: The absorber layer includes a CrON layer in which the nitrogen content is greater than the oxygen content.

5. The reflective mask according to claim 1, wherein: In a plan view, the size of the outer periphery of the absorber layer is smaller than the size of the outer periphery of the substrate.

6. The reflective mask according to claim 5, wherein: In plan view, the dimensions of the outer periphery of the absorber layer range from 138 mm x 138 mm to 142 mm x 142 mm, and in plan view, the dimensions of the outer periphery of the substrate range from 148 mm x 148 mm to 152 mm x 152 mm.

7. The reflective mask according to claim 1, wherein: The absorber layer includes a region formed of CrO or Cr.

8. A reflective mask comprising: substrate; a reflective multilayer disposed on the substrate; A cap layer, disposed on the reflective multilayer; An intermediate layer, disposed on the cap layer; as well as an absorbent layer disposed on the intermediate layer, The absorber layer includes a CrN or CrON layer having a nitrogen concentration higher in a surface region of the absorber layer than in a region deeper than the surface region of the absorber layer.

9. The reflective mask according to claim 8, wherein: The absorber layer has a thickness equal to or less than 45 nm.

10. The reflective mask according to claim 8, wherein: The intermediate layer includes at least one of the following: TaB, TaO, TaBO or TaBN, silicon, a silicon-based compound, ruthenium or a ruthenium-based compound.

11. The reflective mask according to claim 8, wherein: The intermediate layer includes at least one of the following: titanium oxide TiO2, tin oxide SnO, zinc oxide ZnO or cadmium sulfide CdS.

12. The reflective mask according to claim 8, wherein: The absorber layer includes a CrON layer in which the nitrogen content is greater than the oxygen content.

13. The reflective mask according to claim 8, wherein: In plan view, the dimensions of the outer periphery of the absorber layer range from 138 mm x 138 mm to 142 mm x 142 mm, and in plan view, the dimensions of the outer periphery of the reflective multilayer range from 148 mm x 148 mm to 152 mm x 152 mm.

14. The reflective mask according to claim 8, wherein: The absorber layer includes a region formed of CrO or Cr, the region having a thickness of at least 1 nm. 3 volume.

15. The reflective mask according to claim 14, wherein: The volume of the region is 1 nm 3 -10 nm 3 .

16. A method for manufacturing a reflective mask, the method comprising: forming a photoresist layer on a mask blank, the mask blank comprising a substrate, a reflective multilayer on the substrate, a cap layer on the reflective multilayer, an absorber layer on the cap layer, and a hard mask layer, the absorber layer being formed of Cr, CrO or CrON; patterning the photoresist layer; patterning the hard mask layer by using a patterned photoresist layer; patterning the absorber layer by using the patterned hard mask layer; as well as introducing additional elements into the patterned absorber layer to form a converted absorber layer, Wherein, the converted absorber layer has a non-uniform concentration of the additional element along a horizontal direction parallel to the surface of the substrate.

17. The method according to claim 16, wherein: The additional element is nitrogen.

18. The method according to claim 17, wherein: The nitrogen is introduced by an ion implantation operation.

19. The method according to claim 17, wherein: The nitrogen is introduced by a plasma process.

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