TWI776398B - Manufacturing method of mask - Google Patents

Abstract

A method of fabricating a mask is provided. The method includes providing a hard mask layer disposed on top of absorber, a capping layer, and a multilayer that are disposed on a substrate. The method includes forming a middle layer over the hard mask layer, forming a photo resist layer over the middle layer, patterning the photo resist layer, etching the middle layer through the patterned photo resist layer, etching the hard mask layer through the patterned middle layer, and etching the absorber through the patterned hard mask layer. In some embodiments, etching the hard mask layer through the patterned middle layer includes a dry-etching process that has a first removal rate of the hard mask layer and a second removal rate of the middle layer, and a ratio of the first removal rate of the hard mask layer to the second removal rate of the middle layer is greater than 5.

Description

How to form a mask

The present disclosure relates to methods of forming photomasks.

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 technique, the reticle is an important part of the lithography operation. For example, in EUV lithography, it is critical to fabricate EUV photomasks with high contrast between high reflectivity portions and high absorbance portions. As dimensions shrink to make smaller features, newer integrated circuit technologies require finer patterns with narrower critical dimensions. Therefore, new and improved EUV photomask film structures are needed to increase lithography resolution, and more robust processes are required to manufacture such EUV photomasks.

According to some embodiments of the present disclosure, there is provided a method of forming a photomask, comprising: providing a hard mask layer, a cover layer disposed on top of an absorber and multiple layers disposed on the 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; layer etching the hard mask layer; and etching the absorber through the patterned hard mask layer.

According to some embodiments of the present disclosure, there is provided a method of forming a photomask, comprising: forming multiple layers on a substrate; forming an absorber on a cover layer disposed on the multiple layers; forming a hard mask layer on the absorber; forming an intermediate layer layered on the hard mask layer, wherein the intermediate layer comprises a material selected from the group consisting of tantalum oxyboride (TaBO), tantalum boron nitride (TaBN), tantalum boron oxynitride (TaBON), palladium (Pd) or nickel (Ni). one or more of the group consisting of; forming a photoresist layer on the interlayer; patterning the photoresist layer; etching the interlayer through the patterned photoresist layer; and drying the hard mask layer after etching the interlayer An etching process, 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 difference between the first removal rate for the hard mask layer and the second removal rate for the intermediate layer The ratio is greater than 5.

According to some embodiments of the present disclosure, there is provided a method of forming a photomask, comprising: forming an intermediate layer on an EUV film stack, the EUV film stack comprising a substrate, multiple layers on the substrate, and a cover layer on the multiple layers, an absorber on the cover layer and a hard mask layer on the absorber; a photoresist layer is formed on the intermediate layer, wherein the intermediate layer comprises selected from the group consisting of silicon oxide (SiO), silicon oxynitride (SiON), nitride one or more of the group consisting of silicon (SiN), silicon boron nitride (SiBN), silicon borocarbide (SiBC), silicon boron nitride (SiBCN), or polysiloxane; patterned photoresist layer; Patterned interlayer through patterned photoresist layer; patterned through patterned interlayer and patterning the absorber through the patterned hard mask layer.

10: EUV mask structure

20: photoresist layer

30: middle layer

30-1: Middle layer

30-2: Middle layer

30-10: Middle layer

40: Pattern

50: Pattern

100: EUV photomask substrate

101: EUV photomask substrate

110: Hard mask layer

120: Absorber

130: Overlay

140: Multilayer

150: Substrate

160: Conductive layer

S100: Method

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S200: Method

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The present disclosure is 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, the various features are not drawn to scale and are used for illustration purposes only. In fact, the dimensions of the various features may be arbitrarily increased or decreased for clarity of discussion.

FIGS. 1A , 1B and 1C illustrate EUV photomask structures according to various embodiments of the present disclosure.

Figures 2A, 2B, and 2C schematically illustrate strategies for fabricating EUV photomasks according to various embodiments of the present disclosure.

FIGS. 3A , 3B and 3C schematically illustrate sequential process steps of a method for manufacturing an EUV photomask according to various embodiments of the present disclosure.

FIGS. 4A, 4B, 4C, 4D, 4E, and 4F schematically illustrate sequential processes of a method for manufacturing an EUV photomask according to various embodiments of the present disclosure. step.

5 depicts a flowchart of an exemplary method of fabricating an EUV photomask according to various embodiments of the present disclosure.

6 is a flowchart illustrating another exemplary method of fabricating an EUV photomask according to various embodiments of the present disclosure.

FIG. 7 illustrates the fabrication of EUV photomasks according to various embodiments of the present disclosure A flowchart of another exemplary method of .

It should be understood that the following provides many different embodiments or examples for implementing different features of the present disclosure. Specific embodiments or examples of elements and configurations are described below to simplify the present disclosure. Of course, these are only examples and are not intended to be limiting. For example, the dimensions of the elements are not limited to the disclosed ranges or values, but may depend on process conditions and/or desired characteristics of the device. Furthermore, in the following description, forming a first feature on or over a second feature may include embodiments in which the first feature and the second feature are formed in direct contact, and may also include embodiments in which the first feature and the second feature are formed in direct contact. Embodiments where additional features are formed between features such that the first feature and the second feature may not be in direct contact. Various features may be arbitrarily drawn in different scales for simplicity and clarity.

What's more, spatially relative terms (eg, "below", "below", "below", "above", "above", etc. related terms) are used here to simply describe the elements shown in the figures or The relationship of a feature to another element or feature. In use or operation, these spatially relative terms encompass different turns of the device in addition to the turns shown in the figures. Furthermore, these devices can be rotated (90 degrees or other angles) and the spatially relative descriptors used herein can be interpreted accordingly. Additionally, the term "made of" can mean "comprising" or "consisting of." In this 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), unless otherwise stated, not Represents one element from A, one element from B, and one element from C.

Embodiments of the present disclosure provide a method of manufacturing an EUV photomask. The present disclosure provides methods and techniques to enhance lithography resolution, and more robust processes are required to manufacture such EUV photomasks. More specifically, the present disclosure relates to new film structures for the fabrication of EUV photomasks that include an interlayer between a photoresist layer and a hardmask layer, also referred to herein as a "three-layer strategy." This three-layer strategy can be incorporated into the wafer process and implemented in EUV lithography, where the intermediate layer is configured to have etch selectivity for the photoresist layer on top and the hardmask layer below. According to various embodiments of the present disclosure, a relatively thin photoresist layer can be used to transfer the pattern to the intermediate layer, wherein the etch selectivity of the intermediate layer can alleviate the problem of rounding due to the loss of the photoresist layer, thereby increasing the pattern fidelity. The use of an intermediate layer can alleviate conventional problems, such as a high aspect ratio photoresist layer that results in loss of photoresist layer and rounded corners of the pattern when the lateral dimension of the photoresist is much smaller than the thickness of the photoresist and/or pattern 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 EUV photomask substrates and improves current EUV photomask manufacturing processes and facilitates the development of next generation EUV photolithography.

Typically, scanners used in EUV lithography use light in the extreme ultraviolet (EUV) region, where the wavelength of light is from about 1 nm to about 100 nm (eg, 13.5 nm). nanometer). The reticle is a key element of an EUV lithography system. Because the optical material is opaque to EUV radiation, EUV reticles are reflective reticles. A circuit pattern is formed in an absorber layer disposed over the reflective structure. The absorber has low EUV reflectance (eg, less than 3% to 5%). The present disclosure provides EUV reflective masks with fine patterns of narrow critical dimensions. Using the disclosed EUV photomask scheme and process, the fine pattern with high aspect ratio in the original photoresist layer is transferred to the absorber layer in the EUV photomask with better pattern fidelity.

FIGS. 1A , 1B and 1C illustrate an EUV photomask structure 10 (also referred to as an EUV photomask) according to various embodiments of the present disclosure. As shown in FIGS. 1A , 1B and 1C, a desired EUV photomask with circuit patterns is formed from the EUV photomask structure 10, which is shown as having a set of The photoresist layer 20 and the intermediate layer 30 on the EUV photomask substrate 100 . Referring to FIG. 1A , according to different embodiments of the present disclosure, an EUV photomask substrate 100 includes a hardmask layer 110 , an absorber (also referred to as an absorber layer, an absorber layer) 120 , a cover layer 130 , ( reflective) multilayer 140, substrate 150 (also referred to herein as a low-thermal expansion material (LTEM) 150), and conductive layer 160. In some embodiments, modified EUV reticle substrate 100 (which is referred to as EUV reticle substrate 101) may include intermediate layer 30, hard mask layer 110, absorber 120, cover layer 130, multilayer 140, substrate 150, and conductive layer 160. Unless expressly stated otherwise Note, otherwise the EUV photomask substrate 101 is the EUV photomask substrate 100 with the intermediate layer 30 (eg, the 1A, 1B and 1C). Thus, in some embodiments, if the reticle substrate is referred to as EUV reticle substrate 101, the hard mask layer 110 may be referred to as the first hard mask layer, and the intermediate layer 30 may be referred to as the first hard mask layer The second hard mask layer.

According to various embodiments, the method of manufacturing an EUV reticle starts with EUV reticle substrate 100 and, if an intermediate layer is already on substrate 100 , with EUV reticle substrate 101 . In different embodiments, the intermediate layer 30 and the photoresist layer 20 are disposed on the EUV photomask substrate 100 to obtain the EUV photomask structure 10 . According to various embodiments, the intermediate layer 30 is selected to have etch selectivity to the photoresist layer 20 and the top layer (hard mask layer 110 ) of the EUV reticle substrate 100 .

In various embodiments, the photoresist layer 20 includes a positive chemically amplified resist (PCAR), a negative chemically amplified resist (NCAR), a non-chemically amplified photoresist that is sensitive to electron beam exposure Amplified photoresist (non-chemically amplified resist, Non CAR) photoresist layer or inorganic photoresist (for example, metal photoresist (metal photoresist, MePR) or hydrogen silsesquioxane (hydrogen silsesquioxane, HSQ)). The thickness of the photoresist layer 20 is 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 meters to about 150 nanometers and including any thickness value or range in between.

In various embodiments, the intermediate layer 30 includes a material that can absorb extreme violet Metal or metal alloy film for external light. Non-limiting examples of metals that may serve as the intermediate layer 30 include transition metals (eg, tantalum (Ta), palladium (Pd), nickel (Ni)) and their alloys (eg, tantalum oxyboride (TaBO), nitrogen boron tantalum (TaBN), etc.). In various embodiments, the interlayer 30 includes a silicon-based material (eg, silicon oxide (SiO), silicon oxynitride (SiON), silicon nitride (SiN), silicon boron nitride (SiBN), silicon boron carbide ( SiBC), silicon boron nitride (SiBCN) or polysiloxane). The thickness of the intermediate layer 30 is about 2 nm to about 200 nm, 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 nanometers, and including any thickness value or range in between. 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 formation method.

As shown in FIG. 1B , according to various embodiments, the intermediate layer 30 includes two intermediate layers (also referred to herein as sublayers) 30 - 1 and 30-2. In some embodiments, the middle layer 30-1 (bottom sublayer) may include a silicon-containing material, and the middle 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. As shown in Figure 1C, the root According to different embodiments, the intermediate layer 30 may be a multi-layer stack, that is, it is a plurality of intermediate layers (sub-layers) 30-1, 30-2, . . . , 30- having a combination of metal oxide and silicon-based materials 10, with layers ranging from about 2 to about 10. According to various embodiments, each of the intermediate layers 30-1, 30-2, . . . , 30-10 has a thickness of about 1 to about 30 nanometers, about 2 to about 30 nanometers to about 20 nanometers, or about 1 nanometer to about 10 nanometers, and including any thickness value or range therebetween. In some embodiments, the thickness of the multi-layered intermediate layer 30 is about 4 nm to about 200 nm, about 4 nm to about 150 nm, about 4 nm to about 100 nm, about 3 nm to about 50 nm or about 3 nm to about 30 nm, and including any thickness value or range therebetween. In some embodiments, the multi-layered interlayer 30 helps maintain high pattern fidelity during hard mask layer etching. In some embodiments, the multi-layered interlayer 30 helps reduce photoresist loss.

In various embodiments, the intermediate layer 30 has etch selectivity to the photoresist layer 20 and the hard mask layer 110 . For example, the silicon-based interlayer 30 can be etched by a mixed gas plasma carbon tetrafluoride/oxygen (CF ₄ /O ₂ ) at etch rates as high as 600 angstroms per second (A/s), which can be as high as 40 The etch rate of Angstrom/sec etches the hard mask layer 110 comprising chromium oxynitride (CrON). Under similar conditions, the etch rate of the photoresist layer 20 is about 220 angstroms/second to about 240 angstroms/second. Under certain conditions, the etch selectivity of the interlayer 30 to the hard mask layer 110 may be as high as 80:1, which may help facilitate thinning of the interlayer 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 than the absorber layer 120 .

In various embodiments, the function of the hard mask layer 110 is to perform pattern transfer to the absorber layer. The hard mask layer 110 includes a metal layer (eg, chromium (Cr) or tantalum (Ta)), or an alloy thereof (eg, chromium oxynitride (CrON), tantalum oxide (TaO), tantalum oxyboride (TaBO)) . In various embodiments, the hard mask layer 110 includes silicon, a silicon-based compound (eg, silicon nitride (SiN) or silicon oxynitride (SiON)). The thickness of the hard mask layer 110 is in the 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 , and includes any thickness value or range in between. 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 (eg, sputtering), or any other suitable film formation method.

In various embodiments, the thickness ratio of the photoresist layer 20 to the intermediate layer 30 is from about 1:1 to about 75:1, from about 1:1 to about 50:1, from about 1:1 to about 25:1 1 and including any scale range or scale value therebetween. In various embodiments, the thickness ratio of the intermediate layer 30 to the hard mask layer 110 is from about 1:1 to about 100:1, from about 1:1 to about 75:1, from about 1:1 to about 50 : 1. In the range from about 1:1 to about 25:1 and including any range or ratio therebetween. This ratio can be selected in order to adjust the dry etch chemistry to have high etch selectivity in the etch between the photoresist layer 20 and the hard mask layer 110 without loss of pattern fidelity. In various embodiments, the thickness of the intermediate layer 30 is chosen such that it is not possible to Dry etch lift off that can damage the extension of the open hardmask area. In various embodiments, the thickness of the interlayer 30 is selected such that it can withstand the plasma during hard mask layer etching without loss of pattern fidelity.

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

In some embodiments, an anti-reflection layer (not shown in FIG. 1 ) is optionally disposed over the absorber 120 . In some embodiments, the anti-reflective 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 boron oxide (TaBO) layer having a thickness in the range of about 12 nanometers to about 18 nanometers is used as the antireflective layer. In some embodiments, the thickness of the antireflection layer is in the range of about 3 nanometers to about 6 nanometers. In some embodiments, the anti-reflective layer is formed by chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, physical vapor deposition, or any other suitable film formation method.

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 the multilayer 140 from oxidizing. In various embodiments, the capping layer 130 includes ruthenium, a ruthenium alloy (eg, ruthenium boride (RuB), ruthenium silicide (RuSi), or ruthenium niobium (RuNb)), or ruthenium oxide (eg, ruthenium oxide (RuO ₂ )) or ruthenium niobium oxide (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 including any thickness value or range therebetween. In some embodiments, capping layer 130 has a thickness of 3.5 nm±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 (eg, sputtering), or any other suitable film formation method. In some embodiments, a silicon (Si) layer is used as the capping layer 130 .

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 multi-layer 140 includes a film stack including a molybdenum and silicon pair and a top silicon protection layer. In some embodiments, 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 multilayer 140 is greater than about 70% for wavelengths of interest (eg, 13.5 nm). In some embodiments, the pair of silicon and molybdenum layers is formed by chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, physical vapor deposition (sputtering), or any other suitable film formation method.

In various embodiments, each layer of silicon and molybdenum in multilayer 140 has about 2 nanometers, about 3 nanometers, about 4 nanometers, about 5 nanometers, about 6 nanometers, about 7 nanometers, about 8 nanometers A thickness of nanometers, about 9 nanometers, or about 10 nanometers, and including any thickness values in between. 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 is about 4 nanometers thick, and each molybdenum layer is about 3 nanometers thick.

In some embodiments, multilayer 140 includes alternating molybdenum and beryllium layers. In some embodiments, the number of layers in multilayer 140 ranges from about 20 to about 100, although any number of layers is permissible as long as sufficient reflectivity is maintained to image the target substrate. In some embodiments, the reflectivity is higher than about 70% for the wavelength of interest (eg, 13.5 nm). In some embodiments, multilayer 140 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 various embodiments, the substrate 150 includes titanium doped silicon dioxide ( _SiO2 ), low thermal expansion glass, or quartz (eg, fused silica or fused silica). In some embodiments, the substrate 150 transmits light at wavelengths of visible light, 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 150 absorbs extreme ultraviolet wavelengths and deep ultraviolet wavelengths close to the extreme ultraviolet light. In some embodiments, the substrate 150 dimensions are 152 mm in length and 152 mm in width and have a thickness of about 0.25 inches.

In various embodiments, the conductive layer 160 includes a metal layer used to mount the EUV reticle to a reticle holder in an EUV exposure tool. In some embodiments, the conductive layer 160 includes a tantalum-based material (eg, 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 ), pentatantalum hexaboride ( _Ta5B6 ), tritantalum tetraboride ( _Ta3B4 ), and tantalum diboride ( _{TaB2 )} . In some embodiments, the tantalum boride is polycrystalline or amorphous. In some embodiments, the conductive layer 160 includes a chromium-based conductive material (eg, chromium nitride (CrN) or chromium oxynitride (CrON)). In some embodiments, the layer resistance of the conductive layer 160 is about 0.1Ω/sq to about 20Ω/sq, about 0.15Ω/sq to about 15Ω/sq, about 0.2Ω/sq to about 10Ω/sq, or about 0.3Ω/sq sq to about 100 Ω/sq, and including any value or range of layer resistance in between.

In some embodiments, the surface roughness Ra of the conductive layer 160 is equal to or less than 0.25 nm. In some embodiments, the surface roughness Ra of the conductive layer 160 is equal to or greater than 0.05 nm. Furthermore, in some embodiments, the flatness of the conductive layer 160 is equal to or less than 50 nm (within the EUV mask). In some embodiments, the flatness of the conductive layer 160 is greater than 1 nm. 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, this 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 formation method. In the case of chemical vapor deposition, in some embodiments, the source gases include tantalum pentachloride (TaCl5 ₎ and boron trichloride ( _BCl3 ).

2A, 2B, and 2C schematically illustrate process strategies for fabricating EUV photomasks according to various embodiments of the present disclosure. This process strategy includes a three-layer strategy to achieve high pattern fidelity and lithography resolution.

FIGS. 2A , 2B, and 2C schematically illustrate the progression of the process strategy at three exemplary stages of the process, starting with EUV mask structure 10 . FIG. 2A shows the manufacturing stage of the EUV photomask structure 10 , wherein the photoresist layer 20 is used as a photomask to pattern the intermediate layer 30 on the hard mask layer 110 on the absorber 120 . Through the low aspect ratio pattern defined by the photoresist layer 20, the intermediate layer 30 may be formed using the low aspect ratio photoresist layer 20 as an etch mask. Once the pattern is etched in the intermediate layer 30, the photoresist layer 20 can be removed. FIG. 2B shows the stage of the EUV photomask structure 10 after removing the photoresist layer 20 from the EUV photomask structure 10 . Referring to Figure 2B, the intermediate layer 30 may be used to etch the EUV photomask substrate 100 with high fidelity and resolution. FIG. 2C shows a stage of the EUV reticle structure 10 in which the intermediate layer 30 acts as a reticle to pattern and etch the EUV reticle substrate 100 or any layer of the EUV reticle substrate 100 . As shown in FIG. 1 , according to different embodiments of the present disclosure, EUV photomask substrate 100 refers to a hard mask layer 110 , an absorber 120 , a cover layer 130 , a multilayer 140 , a substrate 150 and a conductive layer 160 . layer stacking.

FIGS. 3A , 3B and 3C schematically illustrate sequential process steps of a method for manufacturing an EUV photomask according to various embodiments of the present disclosure. Figure 3A depicts extreme violet according to various embodiments of the present disclosure The external light mask substrate 100 includes a hard mask layer 110 , an absorber 120 , a cover layer 130 , a multilayer 140 , a substrate 150 and a conductive layer 160 . In some embodiments, EUV photomask substrate 100 may not include all of the layers in the layer stack as shown in FIG. 3A. In some embodiments, EUV reticle substrate 100 may include one or more additional layers than the layer stack shown in FIG. 3A. The EUV photomask substrate 100 shown in FIG. 3A can be formed by various suitable process techniques.

FIG. 3B shows a stage of the manufacturing process in which the intermediate layer 30 is disposed on the EUV photomask substrate 100 . Since the intermediate layer 30 has been described in FIGS. 1A to 1C, it will not be described in detail here. As described above, the intermediate layer 30 may be a single layer, or may include two intermediate layers (sublayers) 30-1 and 30-2, or may have multiple sublayers (ie, intermediate layers 30-1, 30-2). , ..., 30-10), which are shown and described in Figure 1A, Figure 1B, and Figure 1C, respectively. According to various embodiments, any intermediate layer including single or multiple sub-layers 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, such that at least two of the intermediate layers 30-1, 30-2, ..., 30-10 have alternating compositions, thicknesses Or have different physical dimensions or chemical compositions. Similarly, as described above, the interlayer 30 - including the intermediate layer 30 - may be formed by chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition, physical vapor deposition (eg, sputtering), or any other suitable film formation method. 1, 30-2, ..., 30-10 intermediate layer 30.

Figure 3C shows a stage of the manufacturing process in which the photoresist layer 20 is It is arranged on the intermediate layer 30 which has been arranged on the EUV photomask substrate 100 . As already described in Figure 1A, the photoresist layer 20 includes a positive chemically amplified photoresist, a negative chemically amplified photoresist, a non-chemically amplified photoresist layer, or an inorganic photoresist that is sensitive to electron beam exposure (eg, metal photoresist or hydrosilicone hydrochloric acid type). According to different embodiments, the thickness of the deposited photoresist layer 20 may be about 2 nm to about 150 nm, about 5 nm to about 100 nm, about 7 nm to about 75 nm, about 10 nm in the range of from about 50 nanometers to about 50 nanometers, or from about 70 nanometers to about 150 nanometers, and including any thickness value or range therebetween.

FIGS. 4A, 4B, 4C, 4D, 4E, and 4F schematically illustrate the sequence in the manufacturing method of the EUV photomask 10 according to different embodiments of the present disclosure. process steps. It should be understood that additional operations may be provided before, during, and after the process shown in Figures 4A-4F, and that some of the operations described below may be replaced or eliminated as other embodiments of this method. The order of operations and/or processes may be interchanged.

As shown in FIG. 4A , the EUV photomask structure 10 includes a photoresist layer 20 formed over the intermediate layer 30 that has been disposed on the EUV photomask substrate 100 . According to various embodiments of the present disclosure (as shown in FIGS. 3A to 3C ), the photoresist layer 20 and the intermediate layer 30 are disposed on the EUV photomask substrate 100 , and the EUV photomask substrate 100 has Stack of hard mask layer 110 , absorber 120 , cover layer 130 , multilayer 140 , substrate 150 and 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 radiation). 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.

Figure 4B depicts a stage after photoresist layer 20 has been developed using pattern 40, which pattern 40 may correspond to the pattern of semiconductor device features that EUV reticle 10 will form in subsequent operations. Once pattern 40 is formed in photoresist layer 20 , dry etching (or any other suitable process step) is performed to transfer pattern 40 in photoresist layer 20 into intermediate layer 30 . According to some embodiments, etching the intermediate layer 30 using the photoresist layer 20 as a mask helps to reduce corner rounding of the photoresist layer 20 . In some embodiments, the dry etching of the interlayer 30 may be less reactive to the photoresist layer 20 depending on the dry etching method employed. In some embodiments, when the interlayer 30 is etched, an etch with 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 can prevent corner rounding caused during dry etching of the intermediate layer 30 . In some embodiments, the amount of corner rounding of the photoresist layer 20 during etching of the interlayer 30 will be reduced compared to if the interlayer 30 were not used to directly etch the hard mask layer 110 . Without directly etching hard mask layer 110 using interlayer 30 (hard mask layer 110 may include chromium oxynitride (CrON) or chromium (Cr) with any percentage of oxygen and nitrogen), hard mask layer 110 Dry etching may be performed using a mixed gas of chlorine-containing gas (chlorine gas (Cl ₂ ), boron trichloride (BCl ₃ ), carbon tetrachloride (CCl ₄ )) and oxygen gas. 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 (CF ₄ ), trifluoromethane (CHF ₃ ), difluoromethane (CH ₂ F ₂ ), fluoromethane (CH ₃ F) or a combination of these fluorine-containing gases.

According to various embodiments, thinner layers of photoresist layer 20 may be used, which may prevent collapse of high aspect ratio features during development of photoresist layer 20 . In some embodiments, the interlayer 30 may be thinner than the photoresist layer 20 because the interlayer 30 has a higher etch selectivity to the hard mask layer 110 than the photoresist layer 20 is to the hard mask layer 110 . For example, the hard mask layer 110 comprising chromium oxynitride ( _CrON ), in which _dioxide The etch rate for silicon ( _SiO2 ) may only be as high as about 3 Angstroms/sec. Under similar conditions, the etch rate of the photoresist layer 20 is about 220 angstroms/second to about 240 angstroms/second. In some embodiments, the etch selectivity of the interlayer 30 to the hard mask layer 110 is about 80:1, which may help facilitate thinning of the interlayer 30 .

According to various 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 etch selectivity to the photoresist layer 20 and the hard mask layer 110 . In some embodiments, for the hard mask layer 110 with chromium oxynitride (CrON), the intermediate layer 30 is selected to be one or more oxide materials (eg, tantalum boron oxynitride (TaBON) or silicon-based materials), which may Dry etching is performed with carbon tetrafluoride (CF ₄ ), trifluoromethane (CHF ₃ ), difluoromethane (CH ₂ F ₂ ), fluoromethane (CH ₃ F), or a combination of these fluorine-containing gases. In some embodiments, for the hard mask layer 110 having an oxide material (eg, tantalum boron oxynitride (TaBON) or a silicon-based material), the interlayer 30 is selected to be a nitride material (eg, chromium nitride (CrN) or tantalum nitride (TaN)), which can be dry etched using chlorine-containing gas (gases containing chlorine (Cl2 ₎ , boron trichloride ( _BCl3 ), etc.) and optionally mixed with oxygen or an inert gas.

After the etching of the interlayer 30 is complete, the photoresist layer 20 may be stripped using suitable lift-off techniques including wet etching and dry etching, where wet etching includes, for example, using organic materials, eg, using Wet etching using a mixture of sulfuric acid (H ₂ SO ₄ ) and hydrogen peroxide (H ₂ O ₂ ) (SPM) or using a mixture of sulfuric acid (H ₂ SO ₄ ) and hydrogen peroxide (H ₂ O ₂ ) ( After SPM), a surface conditioning-1 (SC-1) treatment with an aqueous solution of ammonia and hydrogen peroxide was used as a cleaning step to remove organic thin layers or for particle removal, using an organic solvent (tetraphenol ethane glycidyl ether ( PGEE) or propylene glycol monomethyl ether ester (PGMEA)) rinses, while dry etching involves the use of any oxidizing 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 ), _N2H4 ) or these hydrogen and nitrogen combination) of dry etching. In some embodiments, the lift-off of the photoresist layer 20 may be omitted until the etching of the hard mask layer 110 is completed.

FIG. 4C shows the stage after the interlayer 30 has been etched (or otherwise formed) with the pattern 40 . Once the pattern 40 has been transferred into the interlayer 30 , the patterned interlayer 30 is used to form the pattern 40 in the hardmask layer 110 of the EUV reticle substrate 100 . According to various embodiments, the hard mask layer 110 may be etched by using chlorine-containing gases (chlorine (Cl ₂ ), boron trichloride (BCl ₃ ) and/or carbon tetrachloride (CCl ₄ )) and oxygen The mixed gas is done by dry etching the hard mask layer 110 which is made of chromium oxynitride (CrON) or chromium (Cr) and the percentages of oxygen and nitrogen are arbitrary. In some embodiments, an inert gas may be used during etching. In some embodiments, the hard mask layer 110 may be etched by using carbon tetrafluoride (CF ₄ ), trifluoromethane (CHF ₃ ), difluoromethane (CH ₂ F ₂ ), fluoromethane (CH ₃ F ) or a combination of these fluorine-containing gases by dry etching the hard mask layer 110 made of metal oxide or silicon-based material.

After the etching of the hard mask layer 110 is completed, the interlayer 30 may be removed by overetching the interlayer 30 with a plasma chemical that reacts with the interlayer 30 . In some embodiments, overetching may be accomplished by dry etching with or without physical bombardment. In some embodiments, carbon tetrafluoride (CF4 ₎ , trifluoromethane (CHF3), difluoromethane ( _{CH2F2 )} , fluoromethane ( _{CH3F )} , or a combination of these fluorine-containing gases may be used Etching metal oxide or silicon based materials. In some embodiments, nitride materials such as chromium nitride (CrN) or tantalum nitride (TaN) may be overetched with chlorine-containing gases such as chlorine (Cl ₂ ), boron trichloride (BCl ₃ ). In some embodiments, a gas mixed with oxygen or an inert gas may be used during etching.

According to various embodiments, plasma chemistries must be selected that have a high etch selectivity for the hard mask layer 110 compared to the pattern-transfer interlayer 30 . In other words, the etch rate of chromium oxynitride (CrON) for the hard mask layer 110 can be adjusted by adjusting the gas ratio of chlorine (Cl ₂ ) and oxygen (O ₂ ), which will change the etch rate of the interlayer 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.

In some embodiments, particularly where the lift-off of the photoresist layer 20 is omitted before the etching of the hard mask layer 110 is completed, the lift-off of the photoresist layer 20 may be accomplished by any conventional lift-off method utilizing organic materials, such as , wet etching using a mixture of sulfuric acid (H ₂ SO ₄ ) and hydrogen peroxide (H ₂ O ₂ ) (SPM) or Surface Conditioning-1 (SC-1), using an organic solvent (tetraphenolic ethane shrunk) Glyceryl ether (PGEE) or propylene glycol monomethyl ether ester (PGMEA)) rinse, or use any oxidizing plasma chemical (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 ), _N2H4 ) or these hydrogen and nitrogen combination) of dry etching. In these embodiments, oxidative or reductive dry etching methods may selectively remove or strip the photoresist layer 20 because these etching methods may not react with the interlayer 30 .

FIG. 4D shows the stage after the hard mask layer 110 has been etched (or otherwise formed) with the pattern 40 . Once pattern 40 has been transferred into hard mask layer 110, pattern 40 is formed in absorber 120 by dry etching exposed portions of pattern 40 in absorber 120 using patterned hard mask layer 110 as an etch mask. A dry etch (or any suitable wet etch) may be performed to remove exposed portions in absorber layer 120 to form pattern 40 in absorber 120 . Once the pattern 40 has been transferred onto the absorber 120 , the remaining portions of the hard mask layer 110 may be removed by overetching the hard mask layer 110 with a plasma chemistry that reacts with the hard mask layer 110 . In some embodiments, overetching may be accomplished by dry etching with or without physical bombardment. In some embodiments, carbon tetrafluoride (CF4 ₎ , trifluoromethane (CHF3), difluoromethane ( _{CH2F2 )} , fluoromethane ( _{CH3F )} , or a combination of these fluorine-containing gases may be used Etching metal oxide or silicon based materials. In some embodiments, nitride materials such as chromium nitride (CrN) or tantalum nitride (TaN) may be overetched with chlorine-containing gases such as chlorine (Cl ₂ ), boron trichloride (BCl ₃ ). In some embodiments, a gas mixed with oxygen or an inert gas may be used during etching.

FIG. 4E shows the stage after the absorber 120 has been etched (or otherwise formed) with the pattern 40 . Once the pattern 40 has been transferred into the absorber 120, additional etching of the capping layer 130 or multilayers 140 may be performed. In some embodiments, by repeating another set of suitable processing steps (eg, by using another (second) photoresist layer to form a pattern and use it as an etch mask to perform in EUV reticle 10 etching (dry or wet), another pattern 50 can be transferred into the EUV reticle 10 . According to various embodiments, pattern 50 defines a black border pattern of EUV reticle 10 .

FIG. 4F shows the stage after the pattern 50 has been transferred into the EUV reticle 10 . Pattern 50 is transferred into cap layer 130 and multilayer 140 as shown in Figure 4F. Once the pattern transfer of pattern 50 is complete, the The second photoresist layer is removed through a suitable photoresist layer 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, the pattern 50 in the absorber 120 , the cover layer 130 , and the multilayer 140 defines the black boundary of the EUV reticle 10 . After removing the second photoresist layer, the EUV reticle 10 is subjected to cleaning operations, inspections, and repairs as needed to provide the finished EUV reticle 10 .

FIG. 5 illustrates a flowchart of a method S100 of manufacturing an EUV photomask according to various embodiments of the present disclosure. According to various embodiments, method S100 includes providing, in step S110, a hard mask layer disposed on top of the absorbent body, a cover layer, and multiple layers disposed on a substrate. In some embodiments, the hard mask layer includes a metal layer (eg, chromium (Cr) or tantalum (Ta)) or alloys thereof (eg, chromium oxynitride (CrON), tantalum boride (TaB), tantalum oxide ( TaO), tantalum oxyboride (TaBO) or tantalum boron nitride (TaBN)), or silicon-based compounds (eg, silicon nitride (SiN) or silicon oxynitride (SiON)). The thickness of the hard mask layer is in the 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 (eg, sputtering), or any other suitable film formation method. In some embodiments, the absorber includes a metal layer for absorbing EUV light on the EUV exposure tool. The absorber includes a tantalum based material. In some embodiments of the present disclosure, the absorbent body has a multilayer structure as described below. In various embodiments, the absorber includes tantalum (Ta), cobalt (Co), chromium (Cr), tellurium (Te), platinum (Pt), palladium (Pd), ruthenium (Ru), iridium (Ir), A layer of nickel (Ni) and/or alloys thereof (eg, derivatives of nitrides, carbides, oxides and/or borides). In some embodiments, the capping layer includes a metal layer such as, but not limited to, ruthenium, a ruthenium alloy (eg, ruthenium boride (RuB), ruthenium silicide (RuSi), or ruthenium niobium (RuNb)), or ruthenium oxide (eg, ruthenium oxide Ruthenium (RuO ₂ ) or ruthenium niobium oxide (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 including any thickness value or range therebetween. In some embodiments, the multilayer includes a film stack including pairs of molybdenum and silicon including about 30 alternating layer pairs, about 40 alternating layer pairs, about 50 alternating layer pairs of each of silicon and molybdenum Or about 60 alternating layer pairs. In some embodiments, the multilayer includes as many as 50 pairs of molybdenum and silicon layers, and a top silicon protection layer. In some embodiments, the reflectivity of the multilayer is greater than about 70% for wavelengths of interest (eg, 13.5 nm). In some embodiments, the substrate includes titanium-doped silicon oxide ( _SiO2 ), low thermal expansion glass, or quartz (eg, fused silica or fused silica). In some embodiments, the substrate transmits visible light wavelengths, a portion of infrared light wavelengths near the visible spectrum (near infrared light), and a portion of ultraviolet light wavelengths. In some embodiments, the substrate absorbs extreme ultraviolet wavelengths and deep ultraviolet wavelengths near such extreme ultraviolet light.

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 the range of 2 nm to 200 nm. In some embodiments, the thickness of the intermediate layer is about 2 nm to about 150 nm, about 2 nm to about 100 nm, about 2 nm to about 50 nanometers or in the range of about 2 nanometers to about 30 nanometers. In some embodiments, the intermediate layer includes a material selected from the group consisting of tantalum oxyboride (TaBO), tantalum boron nitride (TaBN), tantalum boron oxynitride (TaBON), palladium (Pd), nickel (Ni), silicon oxide ( SiO), Silicon Oxy Nitride (SiON), Silicon Nitride (SiN), Silicon Boron Nitride (SiBN), Silicon Boron Carbide (SiBC), Silicon Boron Carbide (SiBCN) or Polysiloxane one or more of. 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, and vice versa. 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, multiple interlayers may be etched using different ratios of gas mixtures, such as chlorine, fluorine, and oxygen-containing gases, with the optional addition of an inert carrier gas (eg, helium ( He) or argon (Ar)). Under some conditions, multiple interlayers can help control fine critical dimensions during etching.

Method S100 includes forming a photoresist layer over the intermediate layer in step S130. In some embodiments, the photoresist layer includes a positive type chemically amplified photoresist, a negative type chemically amplified photoresist, and a non-chemically amplified photoresist layer that are sensitive to electron beam exposure. In some embodiments, the thickness of the photoresist layer 20 is about 2 nm to about 120 nm, about 5 nm to about 100 nm, about 7 nm to about 75 nm, about 10 nm to about 50 nm nanometers, or in the range of about 70 nanometers to about 120 nanometers.

The method S100 includes patterning the photoresist layer in step S140. In some embodiments, patterning the photoresist layer includes passing the electron beam Or after the ion beam is patterned, the photoresist layer is exposed to actinic radiation. After exposure to actinic radiation, the exposed photoresist layer is baked and developed to form a pattern in the photoresist layer. Once the photoresist layer 20 is patterned in the photoresist layer, the patterned photoresist layer can be used to form the same pattern in the underlying layers (eg, interlayers) during the fabrication of the reticle.

The method S100 includes etching the intermediate layer through the patterned photoresist layer in step S150. In some embodiments, the etching includes dry etching (or any other suitable process step) that can transfer the pattern in the photoresist layer into the intermediate layer. In some embodiments, etching the interlayer using the photoresist layer as a mask can reduce corner rounding of the photoresist layer. In some embodiments, when etching the interlayer, 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 away and thus prevents corner rounding caused during dry etching of the interlayer. In some embodiments, the dry etching of the interlayer may be one of carbon tetrafluoride (CF ₄ ), trifluoromethane (CHF ₃ ), difluoromethane (CH ₂ F ₂ ), fluoromethane (CH ₃ F), or A combination of these fluorine-containing gases.

The method S100 includes etching the hard mask layer through the patterned interlayer at step S160. According to various embodiments, the etching of the hard mask layer can be carried out by using chlorine-containing gases (chlorine (Cl ₂ ), boron trichloride (BCl ₃ ) and/or carbon tetrachloride (CCl ₄ )) and oxygen The mixed gas is done by dry etching the hard mask layer 110 made of chromium oxynitride (CrON) or chromium (Cr) and the percentages of oxygen and nitrogen are arbitrary. In some embodiments, an inert gas may be used during etching. In some embodiments, the hard mask layer can be etched by using carbon tetrafluoride (CF ₄ ), trifluoromethane (CHF ₃ ), difluoromethane (CH ₂ F ₂ ), fluoromethane (CH ₃ F) Or a combination of these fluorine-containing gases to dry-etch a hardmask layer made of metal oxide or silicon-based materials. In some embodiments, an inert gas may be used during etching. In some embodiments, a hard mask layer comprising chromium oxynitride (CrON) may be etched by mixed gas plasma chlorine/oxygen gas (Cl2/ _{O2 )} at etch rates up to about 240 Angstroms/sec.

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 interlayer includes a dry etch process having a first removal rate for the hard mask layer and a second removal rate for the interlayer, and The ratio of the first removal rate of the mask layer to the second removal rate of the intermediate layer is greater than 5.

In some embodiments, the absorber comprises tantalum selected from the group consisting of tantalum, cobalt, chromium, tellurium, platinum, palladium, palladium, ruthenium, iridium, nickel, and/or alloys thereof (eg, nitrides, carbides, oxides and/or boride derivatives) one or more of the group. In some embodiments, the hard mask layer includes chromium oxynitride (CrON) and has a thickness between 2 nm and 15 nm, and/or the capping layer includes ruthenium.

FIG. 6 is a flowchart of a method S200 of manufacturing an EUV photomask according to various embodiments of the present disclosure. Method S200 includes forming a multilayer over the substrate at step S210. In some embodiments, the multilayer includes a film stack including pairs of molybdenum and silicon including about 30 alternating layer pairs, about 40 alternating layer pairs, about 50 alternating layer pairs of each of silicon and molybdenum Or about 60 alternating layer pairs. In some embodiments, the multilayer includes up to 50 pairs of multiple molybdenum and silicon layer pairs, and top silicon protection layer. In some embodiments, the reflectivity of the multilayer is greater than about 70% for wavelengths of interest (eg, 13.5 nm). In various embodiments, each of the silicon and molybdenum in the multilayer has about 2 nanometers, about 3 nanometers, about 4 nanometers, about 5 nanometers, about 6 nanometers, about 7 nanometers, about 8 nanometers nanometers, about 9 nanometers, or about 10 nanometers thick. In some embodiments, the layers of silicon and molybdenum have about the same thickness. In some embodiments, the layers of silicon and molybdenum have different thicknesses. In some embodiments, each silicon layer is about 4 nanometers thick, and each molybdenum layer is about 3 nanometers thick.

In some embodiments, the multilayer includes alternating molybdenum and beryllium layers. In some embodiments, the number of layers in the multilayer ranges from about 20 to about 100, although any number of layers is permissible as long as sufficient reflectivity is maintained to image the target substrate. In some embodiments, the reflectivity is higher than about 70% for the wavelength of interest (eg, 13.5 nm). 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, the silicon and molybdenum layer pairs and/or 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. silicon and beryllium pair.

Method S200 includes forming an absorber over a cover layer disposed on the multilayer at step S220. 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 oxyboride (TaBO), tantalum boron nitride (TaBN), tantalum boron oxynitride (TaBON), palladium (Pd) or nickel (Ni) indivual. 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, the plurality of sublayers includes 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 Sublayers are alternating pairs.

The method S200 also includes forming a photoresist layer over the intermediate layer at step S250. The method S200 includes patterning the photoresist layer in step S260. The method S200 includes etching the intermediate layer through the patterned photoresist layer in step S270.

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 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 thickness of each sub-layer is in the range of 2 nm to 30 nm, and/or the thickness of the intermediate layer is in the range of 4 nm to 200 nm. In some embodiments, the intermediate layer includes a material selected from the group consisting of tantalum oxyboride (TaBO), tantalum boron nitride (TaBN), tantalum boron oxynitride (TaBON), palladium (Pd), nickel (Ni), silicon oxide ( SiO), Silicon Oxy Nitride (SiON), Silicon Nitride (SiN), Silicon Boron Nitride (SiBN), Silicon Boron Carbide (SiBC), Silicon Boron Carbide (SiBCN) or Polysiloxane one or more of them. In some embodiments, the absorbent pack including tantalum, selected from derivatives of tantalum, cobalt, chromium, tellurium, platinum, palladium, palladium, ruthenium, iridium, nickel and/or alloys thereof (e.g., nitrides, carbides, oxides and/or borides) ) one or more of the groups. In some embodiments, the hard mask layer includes chromium oxynitride (CrON) and has a thickness between 2 nm and 15 nm, and/or the capping layer includes ruthenium, and the multilayer includes multiples of up to 50 pairs Molybdenum and Si layer pair. In some embodiments, the method further includes etching the absorber through the patterned hard mask layer.

FIG. 7 is a flowchart of a method S300 of manufacturing an EUV photomask according to various embodiments of the present disclosure. 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 cover layer on the multilayer, an absorber on the cover layer, and an absorber on the cover layer. A hard mask layer on the body. The method S300 includes forming a photoresist layer over the interlayer in step S320, wherein the interlayer includes a layer selected from the group consisting of silicon oxide (SiO), silicon oxynitride (SiON), silicon nitride (SiN), silicon boron nitride (SiBN), One or more of the group consisting of silicon boron carbide (SiBC), silicon 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 at step S340. The method S300 includes patterning the hard mask layer at step S350 by using a patterned intermediate layer. Method S300 includes patterning the absorber at step S360 by using a patterned hard mask layer. In some embodiments, patterning the hard mask layer includes etching the hard mask layer through a dry etch process using the patterned interlayer as a mask, wherein the dry etch process has a first step on the hard mask layer. A removal rate and a second removal for the intermediate layer removal rate, 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 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, the thickness of each sub-layer is in the range of 2 nm to 30 nm, and/or the thickness of the intermediate layer is in the range of 4 nm to 200 nm. In some embodiments, the absorber comprises tantalum selected from the group consisting of tantalum, cobalt, chromium, tellurium, platinum, palladium, palladium, ruthenium, iridium, nickel, and/or alloys thereof (eg, nitrides, carbides, oxides and/or boride derivatives) one or more of the group.

In the present disclosure, a method of fabricating an EUV photomask by using an intermediate layer to enhance etch selectivity between a hardmask layer and a photoresist layer is achieved. The present disclosure provides methods and techniques for enhancing lithography resolution and the more robust process required to fabricate such EUV photomasks. The disclosed fabrication strategies can be used in conjunction with the disclosed film structures for EUV photomask fabrication to improve current EUV photomask fabrication processes and facilitate the development of next-generation EUV photolithography. It will be understood that not all benefits need to be discussed herein, that no particular benefit is required for all embodiments or examples, and that other embodiments or examples may provide different benefits.

According to one aspect of the present disclosure, a method of forming a reticle is provided. The method includes providing a hardmask layer disposed on top of the absorbent body, a cover layer, and multiple layers disposed on a substrate. The method includes forming an intermediate layer over the hard mask layer, forming a photoresist layer over the intermediate layer, patterning the photoresist layer, etching the intermediate layer through the patterned photoresist layer, and etching the hard mask layer through the patterned intermediate layer , and the absorber is etched through the patterned hardmask layer. exist In some embodiments, etching the hard mask layer through the patterned interlayer includes a dry etch process having a first removal rate for the hard mask layer and a second removal rate for the interlayer, and The ratio of the first removal rate of the cap layer to the second removal rate of the intermediate layer is greater than 5. In some embodiments, the thickness of the intermediate layer ranges from 2 nm to 200 nm. In some embodiments, the intermediate layer includes a material selected from the group consisting of tantalum oxyboride (TaBO), tantalum boron nitride (TaBN), tantalum boron oxynitride (TaBON), palladium (Pd), nickel (Ni), silicon oxide ( SiO), Silicon Oxy Nitride (SiON), Silicon Nitride (SiN), Silicon Boron Nitride (SiBN), Silicon Boron Carbide (SiBC), Silicon Boron Carbide (SiBCN) or Polysiloxane one or more of. 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, and vice versa. 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, the absorber comprises tantalum selected from the group consisting of tantalum, cobalt, chromium, tellurium, platinum, palladium, palladium, ruthenium, iridium, nickel, and/or alloys thereof (eg, nitrides, carbides, oxides and/or boride derivatives) one or more of the group. In some embodiments, the hard mask layer includes chromium oxynitride (CrON) and has a thickness between 2 nm and 15 nm, and/or the capping layer includes ruthenium. In some embodiments, the multilayer includes as many as 50 pairs of molybdenum and silicon layers, and a top silicon protection layer.

According to one aspect of the present disclosure, a method of forming a reticle is provided. The method includes forming a multi-layer over a substrate, on a layer disposed on the multi-layer An absorber is formed over the cover layer, a hard mask layer is formed over the absorber, and an intermediate layer is formed over 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 further includes forming a photoresist layer over the interlayer, patterning the photoresist layer, etching the interlayer through the patterned photoresist layer, and performing a dry etching process on the hard mask layer after etching the interlayer. 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 includes a first sublayer and a second sublayer, the first sublayer includes a silicon-containing material, the second sublayer includes a transition metal-containing material, wherein the first sublayer and the second sublayer Layers are alternating pairs. In some embodiments, the thickness of each sub-layer is between 2 nm and 30 nm, and/or the thickness of the intermediate layer is between 4 nm and 200 nm. In some embodiments, the intermediate layer includes a material selected from the group consisting of tantalum oxyboride (TaBO), tantalum boron nitride (TaBN), tantalum boron oxynitride (TaBON), palladium (Pd), nickel (Ni), silicon oxide ( SiO), Silicon Oxy Nitride (SiON), Silicon Nitride (SiN), Silicon Boron Nitride (SiBN), Silicon Boron Carbide (SiBC), Silicon Boron Carbide (SiBCN) or Polysiloxane one or more of. In some embodiments the absorber comprises tantalum selected from the group consisting of tantalum, cobalt, chromium, tellurium, platinum, palladium, palladium, ruthenium, iridium, nickel and/or alloys thereof (eg, nitrides, carbides, oxides and One or more of the group consisting of derivatives of boride). In some embodiments, the hard mask layer includes chromium oxynitride (CrON) and has a thickness between 2 nm and 15 nm, and/or the capping layer includes ruthenium, and the multilayer includes multiples of up to 50 pairs Molybdenum and Silicon pair. In some embodiments, the method further includes etching the absorber through the patterned hard mask layer.

According to one aspect of the present disclosure, a method of forming a reticle is provided. The method includes forming an intermediate layer on an EUV film stack, the EUV film stack including a substrate, a multilayer on the substrate, a cover layer on the multilayer, an absorber on the cover layer, and a layer on the absorber Hard mask layer. The method includes forming a photoresist layer over an interlayer, wherein the interlayer includes a layer selected from the group consisting of tantalum oxyboride (TaBO), tantalum boron nitride (TaBN), tantalum boron oxynitride (TaBON), palladium (Pd), nickel (Ni), Silicon Oxide (SiO), Silicon Oxy Nitride (SiON), Silicon Nitride (SiN), Silicon Boron Nitride (SiBN), Silicon Boron Carbide (SiBC), Silicon Boron Carbide (SiBCN) or Polysilicon One or more of the group consisting of oxanes. The method also includes patterning the photoresist layer, by patterning the interlayer using the patterned photoresist layer, by patterning the hard mask layer by using the patterned interlayer, and by using the patterned hard mask layer Patterned absorber. In some embodiments, patterning the hard mask layer includes etching the hard mask layer by using a dry etch process with the patterned interlayer as a mask, wherein the dry etch process has a first step on the hard mask layer. A removal rate 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 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, the thickness of each sub-layer is between 2 nm and 30 nm, and/or the thickness of the intermediate layer is between 4 nm and 200 nm.

According to one aspect of the present disclosure, an EUV photomask substrate is provided. The EUV photomask substrate includes multiple layers disposed on the substrate, a cover layer disposed on the multiple layers, an absorber disposed above the cover layer, a hard mask layer disposed above the absorber, and a hard mask layer disposed above the absorber. Intermediate layer over cover layer. The etch selectivity of the interlayer to the photoresist is higher than that of the hard mask layer. In some embodiments, the thickness of the intermediate layer is between 2 nm and 200 nm. In some embodiments, the interlayer includes a member selected from the group consisting of tantalum oxyboride (TaBO), tantalum boron nitride (TaBN), tantalum boron oxynitride (TaBON), palladium (Pd), or nickel (Ni). one or more of. In some embodiments, the interlayer includes a layer selected from the group consisting of silicon oxide (SiO), silicon oxynitride (SiON), silicon nitride (SiN), silicon boron nitride (SiBN), silicon boron carbide (SiBC), and boron nitride nitride One or more of the group consisting of silicon (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, and vice versa. 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, the absorber comprises tantalum, or is selected from the group consisting of tantalum, tantalum oxyboride (TaBO), tantalum boron nitride (TaBN), tantalum boron oxynitride (TaBON), palladium (Pd), nickel (Ni) ), silicon oxide (SiO), silicon oxynitride (SiON), silicon nitride (SiN), silicon boron nitride (SiBN), silicon boron carbide (SiBC), silicon boron nitride (SiBCN) or polysiloxane one or more of the groups. In some embodiments, the hard mask layer includes chromium oxynitride (CrON) and has a thickness between 2 nm and 15 nm.

The foregoing has outlined features of several embodiments or examples so that those of ordinary skill in the art may better understand various aspects of the present disclosure. Those of ordinary skill in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same benefits as the embodiments or examples described herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations without departing from the spirit and scope of the present disclosure.

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Claims (10)

A method for forming a photomask, comprising: providing a hard mask layer, a cover layer and a multi-layer arranged on a base material arranged 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, wherein through the patterned The intermediate layer etching the hard mask layer includes a dry etching process, 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 hard mask layer is A ratio of the first removal rate of the cap layer to the second removal rate of the intermediate layer is greater than 5; and the absorber is etched through the patterned hard mask layer. The method of claim 1, wherein the intermediate layer includes a plurality of sublayers, at least one of the sublayers includes a metal-containing material, and at least another sublayer of the sublayers includes a Silicon-containing materials. The method according to claim 1, wherein the intermediate layer comprises a material selected from the group consisting of tantalum oxyboride (TaBO), tantalum boron nitride (TaBN), tantalum boron oxynitride (TaBON), palladium (Pd) or nickel ( Ni) is composed of One or more of the groups. The method according to claim 1, wherein the intermediate layer comprises a material selected from the group consisting of silicon oxide (SiO), silicon oxynitride (SiON), silicon nitride (SiN), silicon boron nitride (SiBN), carbon boride One or more of the group consisting of silicon (SiBC), silicon boron nitride (SiBCN) or polysiloxane. The method according to claim 1, wherein the hard mask layer comprises a metal layer, and the metal layer comprises chromium or titanium, or chromium oxynitride (CrON), tantalum boride (TaB), tantalum oxide (TaO), One of tantalum oxyboride (TaBO) or tantalum boron nitride (TaBN), or a silicon-based compound derived from one of silicon nitride (SiN) or silicon oxynitride (SiON), and has a range of 2nm to 15nm A thickness between meters. A method for forming a photomask, comprising: forming a multilayer on a substrate; forming an absorber on a cover layer disposed on the multilayer; forming a hard mask layer on the absorber; forming an intermediate layer on the hard mask layer, wherein the intermediate layer is selected from the group consisting of tantalum oxyboride (TaBO), tantalum boron nitride (TaBN), tantalum boron oxynitride (TaBON), palladium (Pd) or nickel (Ni) ) one or more of the group consisting of; 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 the hard mask layer A first removal rate of the 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 . The method of claim 6, wherein the intermediate layer includes a plurality of sublayers, wherein at least one sublayer of the sublayers includes a metal-containing material, and at least another sublayer of the sublayers includes A silicon-containing material. The method of claim 6, further comprising etching the absorber through the patterned hard mask layer. A method for forming a photomask, comprising: forming an intermediate layer on an EUV film stack, the EUV film stack comprising a substrate, a multi-layer on the substrate, and a cover layer on the multi-layer, an absorber on the cover layer and a hard mask layer on the absorber; a photoresist layer is formed on the intermediate layer, wherein the intermediate layer is selected from the group consisting of silicon oxide (SiO), oxynitride Silicon (SiON), Silicon Nitride (SiN), Silicon Boron Nitride (SiBN), Silicon Boron Carbide (SiBC), Silicon Boron Carbide (SiBCN) or one or more of the group consisting of polysiloxanes; patterning the photoresist layer; patterning the intermediate layer through the patterned photoresist layer; patterning the hard layer through the patterned intermediate layer a mask layer; and patterning the absorber through the patterned hard mask layer. The method according to claim 9, wherein the absorber comprises tantalum, or is selected from the group consisting of tantalum, cobalt, chromium, tellurium, platinum, palladium, ruthenium, iridium, nickel and/or their alloys (including nitride, one or more of the group consisting of carbides, oxides and/or boride derivatives).

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