Phase shift reticle for use in photolithography

Abstract

A phase shift reticle for a photolithography process in semiconductor fabrication is provided. The reticle comprises a substrate, a reflective structure, a pattern forming layer, and a phase shifter. The reflective structure is disposed on the substrate. The pattern forming layer comprises a first material and is deposited on the reflective structure. The pattern forming layer comprises a pattern trench. The phase shifter comprises a second material and is disposed within the pattern trench. The transmittance of the second material is different from the transmittance of the first material.

Description

Technology Field

[0001] The present disclosure relates to a reticle generally used in a photolithography process, more specifically, to a phase-shift reticle for use in a photolithography process for semiconductor fabrication. Background Technology

[0002] One of the process steps commonly encountered in the fabrication of integrated circuits and other semiconductor devices is photolithography. Generally, photolithography involves using a patterned template to selectively expose a wafer surface to a radiation source to create an etched surface layer. Typically, the patterned template is a reticle, which is a flat glass plate containing a pattern to be reproduced on the wafer. For example, silicon nitride may be deposited on the wafer surface, followed by a coating of a photosensitive liquid polymer or photoresist. Subsequently, exposure light is reflected from the surface of the reticle to project the desired pattern onto the photoresist-coated wafer.

[0003] In the case of negative photoresist, the portion of the photoresist exposed to light is chemically modified and remains unaffected when the wafer is subsequently applied to a chemical medium that removes the unexposed photoresist, leaving the modified photoresist on the wafer in the exact shape of the pattern on the reticle. In the case of positive photoresist, the portion of the photoresist exposed to light is chemically modified and removed when the wafer is subsequently applied to a chemical medium, while the unexposed photoresist remains on the wafer. Subsequently, an etching process is applied to the wafer to remove the exposed portion of the nitride layer, leaving a nitride pattern on the wafer according to the precise design of the mask. This etched layer, alone or in combination with other similarly generated layers, represents the interconnections between devices that characterize the "network" of a specific integrated circuit or semiconductor chip.

[0004] The industrial trend is toward manufacturing chips with smaller and / or higher logic density, requiring much smaller line widths on larger wafers. However, these advancements present the problem of small pitches between patterns. Methods explored to form vertical interconnect access (via) holes with small pitches, e.g., pitches smaller than 40 nm, involve performing the photolithography process multiple times using two or more reticles, each defining a different via hole pattern, which results in increased manufacturing time and reduced throughput capacity.

[0005] Furthermore, the resolution at which a pattern can be reproduced on a wafer surface depends on the wavelength of the exposure used to project the pattern onto the surface of the photoresist-coated wafer. Modern photolithography tools use extreme ultraviolet (EUV) light with a wavelength of 13.5 nm, which enables minimum feature sizes of approximately 7 nm, 5 nm, or less. Nevertheless, to achieve higher image contrast of the desired pattern on the photoresist-coated wafer, a higher exposure dose (i.e., higher output power to generate EUV light) is required, which disadvantageously increases the manufacturing cost of the semiconductor chip.

[0006] Accordingly, the object of the present invention is to provide a modified reticle for patterning via holes in a semiconductor chip having a relatively small pitch using a single reticle and without repeating the photolithography process multiple times. Another object of the present invention is to the manufacture of a phase-shift reticle.

[0007] According to some embodiments, the reticle comprises a substrate, a reflective structure, a pattern forming layer, and a phase shifter. The reflective structure is disposed on the substrate. The pattern forming layer comprises a first material and is deposited on the reflective structure. The pattern forming layer comprises a pattern trench. The phase shifter comprises a second material and is disposed within the pattern trench. The transmittance of the second material is different from the transmittance of the first material.

[0008] According to some other embodiments, the reticle comprises a substrate, a reflective structure, a pattern forming layer, and a phase shifter. The reticle has a black border region and a pattern region surrounded by the black border region. The reflective structure is deposited on the substrate. A frame trench is formed within the reflective structure for the black border region of the reticle. The pattern forming layer is deposited on the reflective structure for the pattern region of the reticle and has a pattern trench formed within the pattern forming layer. The phase shifter is deposited in the pattern trench. The upper surface of the reticle for the pattern region, formed together by the pattern forming layer and the phase shifter, is a flat surface.

[0009] According to some other embodiments, a method for manufacturing a reticle is provided. The method comprises providing a substrate. The method further comprises forming a reflective structure on the substrate. The method further comprises depositing a pattern-forming layer comprising a first material on the reflective structure. Additionally, the method comprises forming a pattern trench in the pattern-forming layer. The method further comprises depositing a phase shifter comprising a second material within the pattern trench. The transmittance of the second material is different from the transmittance of the first material.

[0010] The foregoing summary is provided to facilitate understanding of some of the innovative features unique to the present disclosure and is not intended to be a complete description. A complete understanding of the present disclosure can be obtained by treating the entire specification, claims, drawings, and summary as a whole. Brief explanation of the drawing

[0011] The present disclosure can be more fully understood by considering the following description of various exemplary embodiments in conjunction with the accompanying drawings, wherein: FIG. 1 shows a cross-sectional view of a reticle having a semi-dark pattern forming layer according to some embodiments of the present disclosure. FIG. 2 shows a schematic diagram of a reticle irradiated with radiation light according to some embodiments of the present disclosure and a diagram plotting the wave phase (i) and energy intensity (ii) of the radiation light after it is reflected from the reticle. FIG. 3a shows a schematic diagram of one step of a photolithography process in which a negative tone photoresist is exposed to radiation from a reticle used to form a vertical interconnection access hole, according to some embodiments of the present disclosure. FIG. 3b shows a schematic diagram of one step of a photolithography process in which a negative tone photoresist is exposed to radiation from a reticle used to form a trench line, according to some embodiments of the present disclosure. FIG. 4 shows a cross-sectional view of a reticle having a semi-dark pattern forming layer according to some embodiments of the present disclosure. FIG. 5 shows a schematic diagram of the reticle shown in FIG. 4 irradiated with radiation light according to some embodiments of the present disclosure, and a diagram plotting the wave phase (i) and energy intensity (ii) of the radiation light after it is reflected from the reticle. FIGS. 6a through 6k illustrate various steps of a method for producing a reticle having a semi-dark pattern forming layer according to some embodiments of the present disclosure. Figure 6l shows an enlarged view of the area (A) of Figure 6k. FIGS. 7a through 7f illustrate various steps of a method for producing a reticle having a semi-dark pattern forming layer according to some embodiments of the present disclosure. Figure 7g shows an enlarged view of the area (B) of Figure 7f. FIGS. 8a through 8f illustrate various steps of a method for producing a reticle having a semi-dark pattern forming layer according to some embodiments of the present disclosure. Although the present disclosure is applicable to various modifications and alternative forms, details thereof are presented as examples in the drawings and will be described in detail. However, it should be understood that the present disclosure is not intended to limit aspects thereof to the specific exemplary embodiments described. On the contrary, the intent is to encompass all modifications, equivalents, and alternatives that fall within the spirit and scope of the present disclosure. Specific details for implementing the invention

[0012] The singular form used in this specification and the appended claims includes the plural unless the context clearly indicates otherwise. As used in this specification and the appended claims, the term "or" is generally used to include "and / or" unless the context clearly indicates otherwise.

[0013] The following detailed description will be read by referring to drawings in which similar elements in different drawings are numbered with similar reference numbers. For example, the reticle is referred to collectively or collectively by the number reference 10, and individually by the letter suffix following the number reference 10 (e.g., 10a). The detailed description and drawings are not necessarily to scale, illustrate exemplary embodiments, and are not intended to limit the scope of the disclosure. The illustrated exemplary embodiments are intended only to be illustrative. Selected features of any exemplary embodiment may be incorporated into additional embodiments unless explicitly indicated otherwise.

[0014] FIG. 1 shows a cross-sectional view of a reticle (10) according to some embodiments of the present disclosure. In this disclosure, the term reticle may be used to refer to a quartz blank, a photo-mask, or an EUV mask. In some embodiments, the reticle (10) is a reflective reticle. It is recognized that the embodiments and concepts illustrated herein are applicable to any reticle having a small pitch between two adjacent patterns, including but not limited to a transmissive reticle. In some embodiments, the reticle is used in a photolithography process operating in short radiation light, such as extreme ultraviolet (EUV), having a wavelength of about 1 nm to about 100 nm, but light (radiation) of other wavelengths is considered by the present disclosure. In the illustrated embodiments, the mask (10) is a phase difference mask, such as an attenuated phase difference mask (AttPSM).

[0015] In some embodiments, the reticle (10) forms a peripheral region (101), a black border region (102), and a pattern region (103). When viewed in a top view of the reticle (10), the pattern region (103) is located in the center of the reticle (10). The pattern region (103) is a region of the reticle (10) that includes the central region of the integrated circuit device (or chip). For example, the reticle (10) includes a pattern of resistors, capacitors, inductors, diodes, metal-oxide-semiconductor field-effect transistors (MOSFETs), complementary MOS (CMOS) transistors, bipolar junction transistors (BJTs), lateral diffusion MOS (LDMOS) transistors, high-power MOS transistors, Fin-like field-effect transistors (FinFETs), other integrated circuit components, or combinations thereof. In the illustrated embodiment, the reticle (10) includes a pattern of via holes of the integrated circuit device (or chip). The black border area (102) extends around the pattern area (103) and is adjacent to the pattern area (103). The width of the black border area (102) may be in the range of about 2 mm to about 3 mm. A frame trench (19) is formed in the black border area (102) of the reticle (10) to reduce unwanted exposure. The periphery area (101) extends around the black border area (102) and is located between the black border area (102) and the outer edge of the substrate (11). The periphery area (101) does not include the pattern of the integrated circuit device. Structural features of the reticle (10) according to some embodiments of the present disclosure are described in detail below.

[0016] In some embodiments, the reticle (10) comprises a substrate (11), a reflective structure (12), a capping layer (13), a pattern forming layer (14), and an absorbent layer (15). The substrate (11) is generally rectangular in shape, having an upper surface (111) and a lower surface (112). The upper surface (111) faces the lower surface (112) and is spaced apart from the lower surface (112) by a side surface (113). The lower surface (112) may be used as a reference surface during the manufacture and handling of the reticle (10). For example, the lower surface (112) may be held by an electrostatic chuck (8) in the exposure device (1) (Fig. 2). In some embodiments, the substrate (11) is made of a material having a low coefficient of thermal expansion to minimize image distortion caused by heating. Non-limiting examples of materials with a low coefficient of thermal expansion include glass, ceramic, or glass-ceramic. A conductive layer may be formed on the bottom surface (112) for the purpose of electrostatic chucking. The conductive layer may include tantalum boron (TaB) or chromium nitride (CrN) and may be formed on the bottom surface (112) through a suitable deposition technique.

[0017] The reflective structure (12) is configured to reflect radiation light projected onto the reticle (10). In some embodiments, the reflective structure (12) is placed on the upper surface (111) of the substrate (11) and covers a portion of the upper surface (111) located in the peripheral area (101) and pattern area (103) of the reticle (10). In some embodiments, the reflective structure (12) comprises a plurality of film pairs, each film pair comprising a first layer (121) and a second layer (122) located below or above the first layer (121). The number of film pairs within the reflective structure (12) may range from 20 to 80. For example, the reflective structure (12) comprises 40 film pairs. In some embodiments, the first layer (121) and the second layer (122) of each film pair are made of two different materials having different refractive indices at the exposure wavelength. According to one embodiment, the first layer (121) of the film pair is a silicon layer, and the second layer (122) of the film pair is a molybdenum layer. In one embodiment, the first layer (121) of the film pair is a beryllium layer, and the second layer (122) of the film pair is a molybdenum layer. The different reflective layers of the first and second layers (121 and 122) consequently lead to a high reflectivity for exposure to a selected type / wavelength of electromagnetic radiation.

[0018] The thickness of each pair of films of the reflective structure (12) can be determined based on the wavelength and angle of incidence of the exposure. In particular, the thicknesses of the first and second layers (121 and 122) are determined so that maximum constructive interference of the exposure diffracted at each interface and minimum absorption of the exposure can be achieved. For example, for the purpose of EUV photolithography, the first layer (121) (e.g., silicon layer) has a thickness of about 4 nm and the second layer (122) (e.g., molybdenum layer) has a thickness of about 3 nm so that the reflective structure (12) is arranged to exhibit a reflectance of about 70% for radiation light within the EUV range.

[0019] A capping layer (13) is disposed on the side of a reflective structure (12) facing a substrate (11) and is configured to protect the underlying reflective structure (12) during the formation of a pattern forming layer (14). For example, the capping layer (13) is selected from a material that exhibits different etching properties from the pattern forming layer (14). As a result, the capping layer (13) functions as an etching stop layer for patterning or repairing / cleaning the pattern forming layer (14). Non-limiting examples of the capping layer (13) include titanium oxide (TiO) or ruthenium (Ru). The capping layer (13) can be formed on the reflective structure (12) with a thickness ranging from about 2 nm to about 4 nm through a suitable film deposition technique.

[0020] A pattern forming layer (14) is placed on a capping layer (13) and covers a portion of the capping layer (13) located in a pattern area (103) of the substrate (11). The pattern forming layer (14) includes a very fine pattern used to form an image of exposure light reflected by a reticle (10) to imprint a corresponding pattern on a photoresist material coated on a semiconductor wafer. For example, the pattern forming layer (14) is etched to have a plurality of pattern trenches (17). The pattern trenches (17) pass through the pattern forming layer (14) and expose a portion of the capping layer (13) or the reflective structure (12), and are used to form a plurality of via holes and / or trench lines on the semiconductor wafer in a photolithography process. In some embodiments, the pattern forming layer (14) is semi-dark so that exposure light strikes the pattern forming layer (14) and is reflected by the reflective structure (12) to expose the photoresist material coated on the semiconductor wafer. Here, the pattern forming layer (14) is “semi-dark,” meaning that the transmittance of the pattern forming layer (14) to exposure is greater than 0% (i.e., the pattern forming layer is semi-transparent to exposure); in some embodiments, the transmittance of the pattern forming layer (14) to exposure (e.g., EUV light) is greater than 50%; and in one preferred embodiment, the transmittance of the pattern forming layer (14) to exposure is in the range of about 60% to about 70%. Non-limiting examples of the material of the pattern forming layer (14) include molybdenum (Mo), niobium (Nb), palladium (Pd) or ruthenium (Ru) or a mixture thereof.

[0021] The absorbent layer (15) is placed over the reflective structure (12) and covers a portion of the capping layer (13) located in the peripheral region (101) of the reticle (10). In some embodiments, the absorbent layer (15) has an absorbance for exposure greater than the absorbance of the pattern forming layer (14) in the same exposure. For example, the absorbent layer (15) has an absorbance of at least 50% in the exposure, and the pattern forming layer (14) has an absorbance of less than 50% in the same exposure. In some embodiments, the reflectance of the absorbent layer (15) is about 2.7% in the exposure within the EUV range.

[0022] The absorbent layer (15) is made of a material different from that of the pattern forming layer (14). In one embodiment, the absorbent layer (15) comprises tantalum-based materials that are essentially oxygen-free, such as tantalum silicide-based materials (TaSi), tantalum boride-based materials nitride (TaBN), and tantalum nitride-based materials (TaN). In another embodiment, the absorbent layer (15) comprises tantalum- and oxygen-based materials, such as tantalum oxide and nitride and silicon-based materials (TaSiON), tantalum boride oxide-based materials (TaBO), and tantalum oxide and nitride-based materials (TaON). ​​The absorbent layer (15) may be patternless (i.e., without features for forming a circuit pattern on a semiconductor wafer), and the upper surface (151) of the absorbent layer (15) is flat. One or more alignment marks may be formed on the absorbent layer (15).

[0023] In some embodiments, the upper surface (151) of the absorbent layer (15) and the upper surface (141) of the pattern forming layer (14) are located in the same plane. That is, the absorbent layer (15) and the pattern forming layer (14) have the same height relative to the reflective structure (12). In some embodiments, the absorbent layer (15) serves as a support plane for the reticle (10) while the reticle (10) is stored in a reticle pod. By forming an upper surface (141) having the same level as the upper surface (151), the fine features formed on the pattern forming layer (14) can be protected from damage caused by collision with the inner surface of the reticle pod.

[0024] In some embodiments, the frame trench (19) is formed by etching down the absorbent layer (15), the capping layer (13), and the reflective structure (12) to expose the substrate (11) beneath the reflective structure (12) having low reflectivity. When dies on a semiconductor wafer are arranged at close intervals, the image boundary of a single exposure shot will overlap with parts of neighboring dies, which adversely affects the critical dimensions and contrast of the features formed on the edges of the dies. To reduce this unwanted exposure during the photolithography process, the reflective structure (12) within the black border region (102) is removed so that little or no exposure is reflected from the reticle (10) within the black border region (102). In some embodiments, the reflectivity in the black border region (102) of the reticle (10) is, for example, about 0.5% or less, or particularly about 0.05% or less. In some embodiments, the black border area (102) is frame-shaped and surrounds the pattern area (103). In some embodiments, the width of the frame trench (19) is, for example, in the range of about 2 mm to about 3 mm.

[0025] FIG. 2 illustrates a step of a method for performing a photolithography process using a reticle (10) in an exposure device (1) according to some embodiments of the present disclosure. For simplicity, an optical device for delivering exposure in the exposure device (1) is omitted. In some embodiments, when the reticle (10) is transferred into the exposure device (1), the reticle (10) is held by a reticle chuck (8) of the exposure device (1) such that the upper surface (141) of the pattern forming layer (14) and the upper surface (151) of the absorbent layer (15) face downward. The reticle (10) may be positioned parallel to a semiconductor wafer (5) located below.

[0026] Before the photolithography process, the semiconductor wafer (5) may be coated with a photoresist layer (6) containing a photosensitive material. The photoresist layer (6) may be a positive tone or, alternatively, a negative tone. In the illustrated embodiment, the photoresist layer (6) is a negative tone photoresist in which the portion of the photoresist exposed to light becomes insoluble in the photoresist developer, and the portion of the photoresist not exposed to light becomes soluble in the photoresist developer. A non-limiting example of the material of the negative tone photoresist is a metal oxide resist.

[0027] To perform a photolithography process, exposure (9), such as EUV light, is generated from a light source (not shown in the drawing) and projected onto a pattern forming layer (14) of a reticle (10). Subsequently, the exposure (9) is reflected by a reflective structure (12) and transfers the pattern from the reticle (10) to a photoresist layer (6) coated on a semiconductor wafer (5).

[0028] Specifically, as shown in FIG. 2, due to the transmission characteristics of the pattern forming layer (14), a portion of the exposure (9) is incident on the pattern forming layer (14) and is reflected by the reflective structure (12) below the pattern forming layer (14) to produce reflected light (Ta) having a pattern associated with the pattern forming layer (14). Additionally, another portion of the exposure (9) passes through the pattern trench (17) and is reflected by the reflective structure (12) to produce reflected light (Tb) having a pattern associated with the pattern trench (17) of the pattern forming layer (14).

[0029] The exposure (9) may undergo a phase change while passing through the pattern forming layer (14), which causes a phase difference between reflected light (Ta) and reflected light (Tb). Diagram (i) in FIG. 2 shows the phases of reflected light (Ta) and reflected light (Tb) when they leave the reticle (10). As shown in diagram (i), the phase of reflected light (Ta) is different from the phase of reflected light (Tb). The phase difference between reflected light (Ta) and reflected light (Tb) may vary depending on the length of the reflected light (Ta) traveled within the pattern forming layer (14). In some embodiments, the thickness of the pattern forming layer (14) is selected such that the phase difference between reflected light (Ta) and reflected light (Tb) is in the range of about π to about 1.3π.

[0030] Wave interference occurs when the phase difference between reflected light (Ta) and reflected light (Tb) is used. As a result, as shown in diagram (ii) of FIG. 2, the region (602) of the photoresist layer (6) associated with one of the pattern trenches (17) is exposed to light having the lowest intensity. In contrast, the region (601) of the photoresist layer (6) associated with the pattern forming layer (14) is exposed to light having a higher intensity. In a configuration where the photoresist layer (6) is negative tone, the intensity of the exposure light exposed to the region (602) is too low so that the chemical structure of the photoresist layer (6) does not change and is therefore removed after a subsequent development process.

[0031] Various examples of reticles exhibiting a phase shift phenomenon similar to that of the reticle (10) will be described below. In the following description, structural features of reticles similar to those of the reticle (10) shown in FIG. 1 will not be repeated for the sake of brevity.

[0032] FIG. 3a illustrates a schematic diagram of a step of a photolithography process in which a negative tone photoresist is exposed to radiation from a reticle (10a) and used to form vertical interconnected access holes on a photoresist layer (6) according to some embodiments of the present disclosure. It should be understood that in the drawings, the pattern trenches on the reticle (10a) and the openings on the photoresist layer (6) are illustrative for the purpose of describing the invention and are not necessarily scaled to meet actual conditions. In one embodiment, the dimensions of the pattern trenches on the reticle (10a) are four times larger than the dimensions of the openings on the photoresist layer (6). In some embodiments, the reticle (10a) has a pattern forming layer (14a) formed of a semi-dark material, and a plurality of pattern trenches (17a) are formed in the pattern forming layer (14a). As can be seen from the bottom view of FIG. 3a, the pattern trench (17a) may have a square shape with a width ranging from about 60 nm to about 100 nm. The spacing (W1) between two pattern trenches (17a) arranged adjacent to each other is in the range of 20 nm to micrometers. To form a plurality of openings (61) associated with the pattern trench (17a) on a photoresist layer (6) having a negative tone, an exposure having the pattern of the reticle (10a) is projected onto the photoresist layer (6). Then, the photoresist layer (6) is applied to a developing solution to remove parts of the photoresist layer (6) that are not exposed by the exposure or are exposed by light having an intensity lower than that required to trigger a chemical structural change in the photoresist layer (6).

[0033] Compared to a photolithography process using a conventional dark-field binary reticle (i.e., pattern trenches are formed in an opaque absorbent material formed in the pattern area of ​​the reticle) to form via holes on a positive tone photoresist, the photolithography process shown in FIG. 3a has a smaller resist blur. According to one simulation result, the former process has a resist blur of 3.5 nm, and the latter process has a resist blur of less than 2 nm. Thus, via holes with small spacing (e.g., less than 40 nm) can be formed even with the use of a single reticle, thereby significantly reducing manufacturing time and cost. Additionally, due to the semi-dark nature of the pattern forming layer (14a), the output power for generating exposure can be reduced compared to a conventional binary reticle, and thus the power requirements for this photolithography process are reduced. Furthermore, the photolithography process shown in FIG. 3a exhibits better critical dimensional uniformity and better hole circularity.

[0034] Compared to a photolithography process for forming via holes on a negative tone photoresist using a conventional bright-field binary reticle (i.e., a dot-shaped absorbent structure is formed on a reflective structure in the pattern area of ​​the reticle), the photolithography process shown in FIG. 3a exhibits better image contrast. As a result, the opening (61) formed by the reticle (10a) has better critical dimension uniformity and better hole circularity. Additionally, compared to a photolithography process using a bright-field binary reticle, the photolithography process shown in FIG. 3a has a better ability to suppress image defects caused by particles or residues (such as particles (4) shown in FIG. 3a) accumulated on the reticle (10a).

[0035] FIG. 3b illustrates a schematic diagram of a step of a photolithography process in which a negative tone photoresist is exposed to radiation from a reticle (10b) and used to form trench lines on a photoresist layer (6) according to some embodiments of the present disclosure. It should be understood that the pattern trenches on the reticle (10b) and the trenches on the photoresist layer (6) are illustrative for the explanation of the invention and are not necessarily scaled to satisfy actual conditions. In one embodiment, the dimensions of the pattern trenches on the reticle (10b) are four times larger than the dimensions of the trenches on the photoresist layer (6). In some embodiments, the reticle (10b) has a pattern forming layer (14b) formed of a semi-dark material, and a plurality of pattern trenches (17b) are formed in the pattern forming layer (14b). As can be seen from the bottom view of FIG. 3b, the pattern trenches (17b) may have a rectangular shape. The spacing (W2) between two mutually adjacent pattern trenches (17b) is in the range of 12 nm to micrometers. To form a plurality of trenches (62) associated with pattern trenches (17b) on a photoresist layer (6) having a negative tone, an exposure having the pattern of the reticle (10b) is projected onto the photoresist layer (6). Then, the photoresist layer (6) is applied to a developing solution to remove parts of the photoresist layer (6) that are not exposed by the exposure or are exposed by light having an intensity lower than that required to trigger a chemical structural change in the photoresist layer (6).

[0036] In a conventional photolithography process, trench lines are formed by the following steps: forming a pattern on a negative tone photoresist by forming photoresist lines on a substrate using a dark-field binary reticle; depositing an inverse material having etching characteristics different from the photoresist lines on the substrate; and etching back the photoresist lines. However, in the above photolithography process, the pattern lines may collapse during or before the deposition of the inverse material. Conversely, the photolithography process shown in FIG. 3b effectively mitigates the concern of pattern collapse, as trench lines can be formed directly without performing an inverse process.

[0037] Compared to a conventional photolithography process using a bright-field binary reticle to form trench lines on a negative tone photoresist, the photolithography process shown in FIG. 3b exhibits superior image contrast. As a result, the aperture (62) formed by the reticle (10b) has superior line width roughness (LWR) and critical dimension uniformity. Additionally, compared to a photolithography process using a bright-field binary reticle, the photolithography process shown in FIG. 3b has a superior ability to suppress image defects caused by particles or residues (e.g., particles (4) shown in FIG. 3b) accumulated on the reticle (10b).

[0038] The inventors of the present disclosure have discovered that when the intensity of reflected light (Ta) (Fig. 2) is close to the intensity of reflected light (Tb) (Fig. 2), the wave interference between reflected light (Ta) and reflected light (Tb) is amplified. In other words, a greater ratio of the transmittance of the pattern forming layer (14) to the transmittance of the medium deposited in the pattern trench (17) creates better image contrast of the pattern projected onto the semiconductor wafer. Generally, the EUV photolithography process is performed in an ultra-vacuum environment, and thus the pattern trench (17) is free of gas (i.e., the transmittance of the medium deposited in the pattern trench (17) is approximately 1). In order to increase the ratio of the transmittance of the pattern forming layer (14) to the transmittance of the medium deposited in the pattern trench (17), another object of the present disclosure is to enhance the interference of reflected light (Ta) and reflected light (Tb) by providing a reticle having one or more phase shifters located in the pattern trench within the pattern forming layer (14).

[0039] FIG. 4 illustrates a cross-sectional view of a reticle (10c) similar to the reticle (10) of FIG. 1, and the difference between the reticle (10c) and the reticle (10) includes a pattern trench (17) filled with a plurality of phase shifters (18). In some embodiments, the entire area of ​​the upper surface of the reflective structure (12) within the pattern area (103) of the reticle (10c) consists of a first area (R1) and a second area (R2) of the reflective structure (12). As shown in FIG. 4, a pattern forming layer (14) covers the first area (R1) of the reflective structure (12). The pattern forming layer (14) may be placed over the first area (R1) of the reflective structure (12), and a capping layer (13) is placed between the reflective structure (12) and the pattern forming layer (14). The phase shifter (18) is located within the pattern trench (17) and covers the second region (R2) of the reflective structure (12). The phase shifter (18) may be placed over the second region (R2) of the reflective structure (12), and a capping layer (13) is placed between the reflective structure (12) and each phase shifter (18).

[0040] In some embodiments, the pattern forming layer (14) is formed of a first material, and the phase shifter (18) is formed of a second material different from the first material. Exemplary combinations of the first material and the second material according to some embodiments of the present disclosure are presented in Tables 1 and 2.

[0041] Table 1: Combination of pattern forming layer (14) material (first material) and phase shifter (18) material (second material) and light-related parameters emitted from the pattern forming layer (14) and phase shifter (18) having a phase difference of π

[0042]

[0043] Table 2: Combination of pattern forming layer (14) material (first material) and phase shifter (18) material (second material) and combination of light-related parameters emitted from the pattern forming layer (14) and phase shifter (18) having a phase difference of 1.2π

[0044]

[0045] Table 1 indicates that when the pattern trench (17) is filled with a phase shifter (18) comprising a material selected from Zr, La, Si, C, or B, the transmittance ratio of the pattern forming layer (14) to the phase shifter (18) is greater than the transmittance ratio of the pattern forming layer (14) to vacuum (i.e., when the phase shifter (18) is not formed within the pattern trench (17). Table 2 indicates that when the pattern trench (17) is filled with a phase shifter (18) comprising a material selected from La, Si, SiC, or pSi, the transmittance ratio of the pattern forming layer (14) to the phase shifter (18) is greater than the transmittance ratio of the pattern forming layer (14) to vacuum. An increase in the transmittance ratio of the pattern forming layer (14) to the phase shifter (18) means that the wave interference of light reflected by the reticle (10c) is enhanced and the image contrast is significantly improved. For example, as shown in FIG. 5, when the reticle (10c) is used in a photolithography process, a portion of the exposure (9) is incident on the pattern forming layer (14) and reflected by the reflective structure (12) below the pattern forming layer (14) to produce reflected light (Ta) having a pattern associated with the pattern forming layer (14). Additionally, another portion of the exposure (9) is incident on the phase shifter (18) and reflected by the reflective structure (12) below the phase shifter (18) to produce reflected light (Tc) having a pattern associated with the phase shifter (18).

[0046] The exposure (9) undergoes a phase change while passing through the pattern forming layer (14) and the phase shifter (18), which causes a phase difference between the reflected light (Ta) and the reflected light (Tc). Specifically, diagram (i) of FIG. 5 shows the phases of the reflected light (Ta) and the reflected light (Tc) when leaving the reticle (10c), and diagram (ii) of FIG. 5 shows the intensity of the exposure (9) projected onto the semiconductor wafer (5). As shown in diagram (i) of FIG. 5, the phase of the reflected light (Ta) is different from the phase of the reflected light (Tc), and the amplitude of the phase of the reflected light (Tc) is greater than the amplitude of the phase of the reflected light (Ta). As a result, as shown in diagram (ii) of FIG. 5, the region (602) of the photoresist layer (6) associated with one of the phase shifters (18) is exposed to light having the lowest intensity. In contrast, the region (601) of the photoresist layer (6) associated with the pattern forming layer (14) is exposed to light having maximum intensity. Additionally, when affected by the strong amplitude of the reflected light (Tc), the exposure (Tc) transmitted from the phase shifter (18) exhibits a lower intensity than the exposure (Ta) transmitted from the pattern forming layer (14), which means that the interference of the light reflected by the reticle (10c) is enhanced, and thus the image contrast is significantly improved.

[0047] In some embodiments, both the pattern forming layer (14) (first material) and the phase shifter (18) (second material) are alloys formed by more than one elemental atom. An example of the pattern forming layer (14) may be, for example, Ni-Al. The selection of an alloy as the second material (phase shifter) is possible insofar as (1) the ratio of the transmittance of the first material (pattern forming layer) to the second material is greater than the ratio of the transmittance of the first material to vacuum; and (2) a combination of other optical parameters and other related parameters such that the thicknesses of the first material and the second material make the phase difference of light passing through the first material and the second material range from about π to about 1.3π, preferably 1.2π.

[0048] The pattern forming layer may be a single element or an alloy, and the phase shifter may also be a single element or an alloy. The entire system may be a combination of elements and alloys depending on the pattern forming layer and the phase shifter.

[0049] Tables 1 and 2 also show that in some specific combinations, e.g., Mo / La, Mo / Si, and Nb / La, the thickness of the pattern forming layer (14) and the phase shifter (18) corresponds to approximately 50 nm. The pattern forming layer (14) and the phase shifter (18) having such thin thickness can also facilitate the prevention of shadowing effects and the improvement of the light reflectivity of the reticle (10c). That is, the production yield of the semiconductor wafer can be improved. In some embodiments, the pattern forming layer (14) and the phase shifter (18) have a thickness of about 44 nm to about 53 nm.

[0050] In addition to the advantages mentioned above, the deposition of the phase shifter (18) within the pattern trench (17) also provides the benefit of reducing the power consumption of the exposure device and lowering associated costs. According to one simulation result, when the pattern forming layer (14) is made of Mo and the phase shifter (18) is made of silicon, the power of a single exposure shot to effectively expose the photoresist is approximately 36.2 mJ / cm² compared to a reticle without the phase shifter (18) deposited within the pattern trench (17). 2 At approximately 35.0 mj / cm 2 It decreased by 3%.

[0051] To take advantage of the above benefits of the phase shift reticle, it is recognized that the phase difference generated by the reticle can be determined by the wavelength of the exposure. In the present disclosure, the light emitted from the pattern forming layer (14) and the phase shifter (18) may have a phase difference in the range of 1π to 1.3π, and the relevant parameters of the phase shift reticle are shown in Table 3 below.

[0052] Table 3: Light-related parameters emitted from a pattern forming layer (14) (e.g., molybdenum) and a phase shifter (18) (e.g., lanthanum or silicon) having a phase difference in the range of π to 1.3π.

[0053]

[0054] FIGS. 6a through 6l illustrate a series of schematic cross-sectional views illustrating a method for forming a reticle (10d) (Fig. 6k) according to one embodiment of the present invention. Additional steps may be provided before, during, and after the method, and some of the described steps may be replaced, removed, or moved for further embodiments. The method is one example and is not intended to limit the present disclosure beyond what is expressly stated in the claims.

[0055] Referring to FIG. 6a, a method for forming a reticle (10d) comprises sequentially forming a reflective structure (12), a capping layer (13), and a pattern forming layer (14d) on a substrate (11). The pattern forming layer (14d) may be selected from alloys such as molybdenum (Mo), niobium (Nb), palladium (Pd), ruthenium (Ru), or Ni-Al. The reflective structure (12), the capping layer (13), and the pattern forming layer (14d) may be formed by chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), and / or other suitable processes. In some embodiments, the reflective structure (12) is a multilayer comprising alternating Mo and Si layers, and each pair of Mo and Si layers has a Mo layer with a thickness of about 3 nm and a Si layer with a thickness of about 4 nm. The capping layer (13) comprises ruthenium (Ru), RuSi, or a combination thereof and has a thickness in the range of about 2 nm to about 20 nm. The pattern forming layer (14d) comprises molybdenum (Mo) or niobium (Nb) and has a thickness in the range of about 40 nm to about 130 nm.

[0056] Referring still to FIG. 6a, the method for forming the reticle (10d) further includes the step of patterning an area of ​​the pattern forming layer (14d) with respect to the surrounding area (101) and the black border area (102). The patterning process may include forming a layer of photoresist (21) on the pattern forming layer (14d) by a suitable process, such as spin-on coating, and then exposing and developing the layer of photoresist (21) to form a photoresist feature (210). The photoresist feature (210) may be a rectangular shape that exposes the upper surface of the pattern forming layer (14d) with respect to the surrounding area (101) and the black border area (102).

[0057] The method for forming the reticle (10d) further includes performing an etching process to transfer the pattern of the photoresist feature portion (210) to the base pattern forming layer (14d). In the etching process, as shown in FIG. 6b, the portion of the pattern forming layer (14d) not covered by the photoresist (21) is removed so that an opening (140d) is formed therein. After the etching process of the pattern forming layer (14d), the layer of the photoresist (21) can be removed.

[0058] Referring to FIG. 6c, a method for forming a reticle (10d) further comprises forming an absorbent material (150d) on a pattern forming layer (14d) by chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), and / or other suitable processes or processes. The absorbent material (150d) may include a tantalum silicide-based material, a nitrated tantalum boride-based material, and a tantalum nitride-based material.

[0059] After the formation of the absorbent material (150d), as shown in FIG. 6d, a removal process is performed to remove a portion of the absorbent material (150d) over the pattern forming layer (14d) and the opening (140d) to form the absorbent layer (15). The removal process may include a chemical-mechanical polishing (CMP) process or a dry etching process. After the removal process, the absorbent layer (15) and the pattern forming layer (14d) within the opening (140d) have the same height relative to the reflective structure (12). The upper surface (141d) of the pattern forming layer (14d) is substantially coplanar with the upper surface (151) of the absorbent layer (15) so that the pattern forming layer (14d) and the absorbent layer (15) constitute the planar (flat) upper surface of the reticle (10d).

[0060] Referring to FIG. 6e, a method for forming a reticle (10d) further includes the step of patterning a portion of a pattern forming layer (14d) located within a pattern area (103). The patterning process may include forming a photoresist layer (22) on the pattern forming layer (14d) and the absorbent layer (15) by a suitable process, such as spin-on coating, and then exposing and developing the photoresist layer (22) to form photoresist features (220). The photoresist features (220) may be patterned according to the circuit pattern of the layers of the integrated circuit. In some embodiments, the photoresist features (220) are patterned according to via holes or trench lines of the integrated circuit.

[0061] A method for forming a reticle (10d) further includes performing an etching process to transfer the pattern of the photoresist feature portion (220) to the base pattern forming layer (14d). In the etching process, as shown in FIG. 6f, a portion of the pattern forming layer (14d) not covered by the photoresist (22) is removed, and a plurality of pattern trenches (17d) are formed therein. After the etching process of the pattern forming layer (14d), the layer of photoresist (22) can be removed.

[0062] After the formation of the pattern trench (17d), the method for forming the reticle (10d) further includes the step of forming a plurality of phase shifters within the pattern trench (17d). In some embodiments, the phase shifters are formed within the pattern trench (17d) by a self-assembled monolayer (SAM) process and an area-selective deposition (ASD) process.

[0063] Specifically, in the SAM process, as shown in FIG. 6g, an inhibitor (23) is selectively formed on the pattern forming layer (14d) and the absorbent layer (15). That is, the inhibitor (23) covers the upper surface (141d) of the pattern forming layer (14d) and the upper surface (151) of the absorbent layer (15), leaving the pattern trench (17d) uncovered. The inhibitor (23) comprises a material capable of inhibiting subsequent deposition on the pattern forming layer (14d) and the absorbent layer (15). In some embodiments, the inhibitor (23) may be formed by a liquid deposition and / or deposition process. In the ASD process, two types of chemicals are alternately supplied multiple times onto the pattern forming layer (14d) and the absorbent layer (15). Since the inhibitor (23) is non-reactive with the chemicals of the ASD process, the chemicals are prevented from binding to the inhibitor (23). As a result, as shown in FIG. 6h, a phase shifter (18d) can be selectively formed within the pattern trench (17d), and a thin film (180d) of the phase shifter material can be formed on the pattern forming layer (14d) and the absorbent layer (15) after the ASD process. Subsequently, the formation of the inhibitor is removed along with the thin film (180d) on the inhibitor as shown in FIG. 6i. In some embodiments, the phase shifter (18d) is selected from a material comprising Zr, La, Si, C, or B.

[0064] After forming the phase shifter (18d), the method of forming the reticle (10d) further comprises forming a frame trench (19) in the black border region (102) of the reticle (10d). In some embodiments, as shown in FIG. 6j, the formation of the frame trench (19) may include forming a layer of photoresist (24) over the pattern forming layer (14d) and the absorbent layer (15) by a suitable process, such as spin-on coating, and then exposing and developing the layer of photoresist (24) to form a photoresist feature (240). The photoresist feature (240) may have a rectangular shape to expose the upper surface of the absorbent layer (15) located in the black border region (102). After that, an etching process is performed to transfer the pattern of the photoresist feature (240) to the base absorbent layer (15). In the etching process, as shown in FIG. 6k, the absorbent layer (15), capping layer (13), and reflective structure (12) not covered by the photoresist (24) are removed so that a frame trench (19) is formed therein. The photoresist layer (24) may be removed after the etching process to form the frame trench (19). In some embodiments, the reflective structure (12) is completely removed and stops on the surface of the substrate (11).

[0065] In some embodiments, all openings or pattern trenches (17) of the pattern forming layer (14d) are filled with phase shifters (18d), and the upper surface (105d) of the reticle (10d) within the pattern area (103) is a flat surface. In the present disclosure, the “flat surface” is not limited to an ideal flat surface and also includes a surface having a height variation of 5% or less of the height of the phase shifter (18d). For example, as shown in FIG. 6L, the upper surface (181d) of one of the phase shifters (18d) is located at a different level from the upper surface (141d) of the pattern forming layer (14d). The upper surface (181d) of the phase shifter (18d) may be lower than the upper surface (141d) of the pattern forming layer (14d). The height difference (H1) between the upper surface (181d) of the phase shifter (18d) and the upper surface (141d) of the pattern forming layer (14d) may be in the range of about 3% to about 4% of the height of the phase shifter (18d). In the illustrated embodiment, the height difference (H1) between the upper surface (181d) of the phase shifter (18d) and the upper surface (141d) of the pattern forming layer (14d) is about 2 nm. In some embodiments, the two phase shifters (18d) have different heights relative to the upper surface (141d) of the pattern forming layer (14d), and thus different regions of the upper surface (105d) of the reticle (10d) have different height variations.

[0066] FIGS. 7a through 7g illustrate a series of schematic cross-sectional views illustrating a method for forming a reticle (10e) (Fig. 7f) according to one embodiment of the present invention. Additional steps may be provided before, during, and after the method, and some of the described steps may be replaced, removed, or moved for further embodiments. The method is one example and is not intended to limit the present disclosure beyond what is expressly stated in the claims.

[0067] Referring to FIG. 7a, a method for forming a reticle (10e) comprises the step of providing a substrate (11) on which a reflective structure (12), a capping layer (13), a pattern forming layer (14e), an absorbent layer (15), and a buffer layer (25) are formed thereon. The pattern forming layer (14e) may be selected from alloys such as molybdenum (Mo), niobium (Nb), palladium (Pd), ruthenium (Ru), or Ni-Al. The absorbent layer (15) is formed around the pattern forming layer (14e), and the pattern forming layer (14e) and the buffer layer (25) are patterned. The method of forming the absorbent layer (15) and patterning the pattern forming layer (14e) and the buffer layer (25) is similar to the steps illustrated in FIG. 6a through 6f and will therefore not be repeated for brevity.

[0068] Referring to FIG. 7b, after the pattern forming layer (14e) and the buffer layer (25) are patterned, a method for forming a reticle (10e) comprises forming a phase shifter material (180e) on the buffer layer (25) by chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), and / or other suitable processes. The phase shifter material (180e) may comprise, for example, a material selected from Zr, La, Si, C, or B. After the formation of the phase shifter material (180e), the pattern trench (17e) within the pattern forming layer (14e) is filled with the phase shifter material (180e).

[0069] Afterward, a removal process is performed to remove a portion of the phase shifter material (180e) over the buffer layer (25) and the pattern trench (17e) to form a plurality of phase shifters (18e), such as Zr, La, Si, C, B, or their alloys, within the pattern trench (17e). In some embodiments, as shown in FIG. 7c, the removal process is performed. The removal process may include an etching process, a CMP process, or a combination of an etching process and a CMP process. In some embodiments, an etching process is first performed to remove a portion of the phase shifter material (180e) to expose the buffer layer (25). During the etching process, the buffer layer (25) may act as a stop layer to stop the etching process thereon. Next, as shown in FIG. 7d, a CMP process is provided to remove the buffer layer (25) and the remaining phase shifter material (180e) over the pattern trench (17e) to form a phase shifter (18e) within the pattern trench (17e). In some alternative embodiments, the CMP process is first performed until the buffer layer (25) is exposed, and then an etching process is applied to remove the buffer layer (25) and the phase shifter material (180e) over the pattern forming layer (14e).

[0070] After forming the phase shifter (18e), the method of forming the reticle (10e) further includes forming a frame trench (19) in the black border region (102) of the reticle (10e). The formation of the frame trench (19) may include forming a layer of photoresist (26) on the pattern forming layer (14e) and the absorbent layer (15) by a suitable process, such as spin-on coating, and then exposing and developing the layer of photoresist (26) to form a photoresist feature (260) as shown in FIG. 7e. The photoresist feature (260) may have a ring shape to expose the upper surface of the absorbent layer (15) located in the black border region (102). After that, an etching process is performed to transfer the pattern of the photoresist feature (260) to the base absorbent layer (15). As shown in FIG. 7f, in an etching process, the absorbent layer (15), capping layer (13), and reflective structure (12) not covered by the photoresist (26) are removed to form a frame trench (19) therein. The photoresist layer (26) may be removed after the etching process to form the frame trench (19). In another embodiment, the reflective structure (12) is completely removed and remains on the surface of the substrate (11).

[0071] In some embodiments, all openings or pattern trenches (17e) within the pattern forming layer (14e) are filled with phase shifters (18e), and thus the entire upper surface (105e) of the reticle (10e) within the pattern area (103) is a flat surface. In some embodiments, as shown in FIG. 7g, the upper surface (181e) of one of the phase shifters (18e) and the upper surface (141e) of the pattern forming layer (14e) are located at the same level. That is, there is no height difference between the upper surface (181e) of the phase shifter (18e) and the upper surface (141e) of the pattern forming layer (14e). In some alternative embodiments, a recess may be formed during the removal process of the phase shifter material (180e), and thus the upper surface (181e) of one of the phase shifters (18e) may be lower than the upper surface (141e) of the pattern forming layer (14e). The height difference between the upper surface (181e) of the phase shifter (18e) and the upper surface (141e) of the pattern forming layer (14e) may be in the range of about 3% to about 4% of the height of the phase shifter (18e).

[0072] In some embodiments, as shown in FIG. 8f, the absorbent layer (15f) of the peripheral region (101) of the reticle (10f) is made of the same material as the pattern-forming layer (14) of the pattern region (103) of the reticle (10f). FIGS. 8a through 8f illustrate a series of schematic cross-sectional views illustrating a method for forming a reticle (10f) ( FIG. 8f) according to one embodiment of the present invention. Additional steps may be provided before, during, or after the method, and some of the described steps may be replaced, removed, or moved for further embodiments. The method is one example and is not intended to limit the present disclosure beyond what is expressly stated in the claims.

[0073] Referring to FIG. 8a, a method for forming a reticle (10f) comprises sequentially forming a reflective structure (12), a capping layer (13), and a phototransparent material (140f) on a substrate (11). The reflective structure (12), the capping layer (13), and the phototransparent material (140f) may be formed by chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), and / or other suitable processes or processes. In some embodiments, the reflective structure (12) is a multilayer comprising alternating Mo and Si layers. The capping layer (13) comprises ruthenium (Ru), RuSi, or a combination thereof and has a thickness in the range of about 2 nm to about 20 nm. The phototransparent material (140f) comprises molybdenum (Mo) or niobium (Nb) and has a thickness in the range of about 40 nm to about 130 nm.

[0074] Referring to FIG. 8b, a method for forming a reticle (10f) further comprises patterning a portion of a phototransparent material (140f) located in a pattern area (103). The patterning process may include forming a layer of photoresist (22) on the phototransparent material (140f) by a suitable process, such as spin-on coating, and then exposing and developing the layer of photoresist (22) to form photoresist features (220). The photoresist features (220) may be patterned according to the circuit pattern of the layer of the integrated circuit. In some embodiments, the photoresist features (220) are patterned according to via holes or trench lines of the integrated circuit.

[0075] A method for forming a reticle (10f) further includes performing an etching process to transfer a pattern of photoresist features (220) to a base phototransparent material (140f). In the etching process, a portion of the phototransparent material (140f) not covered by the photoresist (22) is removed to form a plurality of pattern trenches (17f) therein, as shown in FIG. 8C. After the etching process of the phototransparent material (140f), a layer of photoresist (22) may be removed.

[0076] After the formation of the pattern trench (17f), the method for forming the reticle (10f) further includes the step of forming a plurality of phase shifters (18f) within the pattern trench (17d) as illustrated in FIG. 8d. The phase shifters (18f) may be formed within the pattern trench (17f) by a self-assembled monolayer (SAM) process and an area-selective deposition (ASD) process, as illustrated in FIG. 6g to 6i. Alternatively, the phase shifters (18f) may be formed within the pattern trench (17f) by depositing a phase shifter material on a pattern forming layer (14f) and performing a removal process such as the process illustrated in FIG. 7a to 7d.

[0077] After forming the phase shifter (18f), the method of forming the reticle (10f) further comprises forming a frame trench (19) within the black border region (102) of the reticle (10f). In some embodiments, as shown in FIG. 8e, the formation of the frame trench (19) may include forming a layer of photoresist (24) on a phototransparent material (140f) by a suitable process, such as spin-on coating, and then exposing and developing the layer of photoresist (24) to form a photoresist feature (240). The photoresist feature (240) may have a rectangular shape to expose the upper surface of the phototransparent material (140f) located within the black border region (102). Then, an etching process is performed to transfer the pattern of the photoresist feature (240) to the base phototransparent material (140f). In the etching process, as illustrated in FIG. 8f, the phototransparent material (140f), capping layer (13), and reflective structure (12) not covered by the photoresist (24) are removed to form a frame trench (19) therein. After the frame trench (19) is formed, the phototransparent material (140f) within the black border region (102) refers to the absorbent layer (15), and the phototransparent material (140f) within the surrounding region (101) refers to the pattern forming layer (14f). The photoresist layer (24) can be removed after the etching process to form the frame trench (19), and the process to form the reticle (10f) is completed.

[0078] Although various exemplary embodiments of the present disclosure have been described as such, those skilled in the art will readily recognize that other embodiments may be made and used within the scope of the claims attached herein. Numerous advantages of the present disclosure covered by this document have been presented in the foregoing description. However, the present disclosure is to be understood, in many respects, merely as illustrative. Changes in details may be made, particularly with respect to the shape, size, and arrangement of parts, without exceeding the scope of the present disclosure. Of course, the scope of the present disclosure is defined in the language in which the attached claims are expressed.

Claims

Claim 1 A reticle comprising: a substrate; a reflective structure disposed on the substrate; a pattern forming layer comprising a first material deposited on the reflective structure, said pattern forming layer comprising a pattern trench; and a phase shifter comprising a second material disposed within the pattern trench, wherein the transmittance of the second material is different from the transmittance of the first material, said first material comprises molybdenum (Mo) or niobium (Nb), and said second material comprises lanthanum (La) or silicon (Si). Claim 2 A reticle according to claim 1, wherein the transmittance of the first material and the transmittance of the second material are both greater than 50% in exposure within the extreme ultraviolet (EUV) range. Claim 3 delete Claim 4 A reticle according to claim 1, comprising an absorbent layer located in a peripheral region of the reticle, wherein the absorbent layer has an absorbance greater than the absorbance of the pattern forming layer in exposure within the EUV range. Claim 5 delete Claim 6 delete Claim 7 A reticle according to claim 1, wherein the exposure transmitted from the pattern forming layer and the exposure transmitted from the phase shifter have a phase difference in the range of π to 1.3π in an exposure within the EUV range. Claim 8 In claim 1, the pattern forming layer and the phase shifter together form an upper surface of the reticle for receiving exposure, and the upper surface is a planar surface of the reticle. Claim 9 A reticle according to claim 1, wherein the difference between the thickness of the pattern forming layer and the thickness of the phase shifter is less than 2 nm. Claim 10 A reticle having a black border region and a pattern region surrounded by the black border region, comprising a substrate; a reflective structure deposited on the substrate, wherein a frame trench is formed within the reflective structure for the black border region of the reticle; a pattern forming layer comprising molybdenum (Mo) or niobium (Nb) deposited on the reflective structure for the pattern region of the reticle, wherein a pattern forming layer having a pattern trench formed within the pattern forming layer; and a phase shifter comprising lanthanum (La) or silicon (Si) deposited within the pattern trench, wherein the upper surface of the reticle for the pattern region formed together by the pattern forming layer and the phase shifter is a flat surface. Claim 11 delete Claim 12 delete Claim 13 In claim 10, a reticle in which the transmittance of the pattern forming layer and the transmittance of the phase shifter are both greater than 50% in exposure within the EUV range. Claim 14 A reticle according to claim 10, wherein the exposure transmitted from the pattern forming layer and the exposure transmitted from the phase shifter have a phase difference in the range of π to 1.3π in an exposure within the EUV range. Claim 15 A reticle according to claim 10, wherein the pattern forming layer has a thickness of 44 nm to 53 nm. Claim 16 A method for manufacturing a reticle, comprising the steps of: providing a substrate; forming a reflective structure on the substrate; depositing a pattern-forming layer containing a first material on the reflective structure; forming a pattern trench within the pattern-forming layer; and depositing a phase shifter containing a second material within the pattern trench, wherein the transmittance of the second material is different from the transmittance of the first material, and the first material contains molybdenum (Mo) or niobium (Nb), and the second material contains lanthanum (La) or silicon (Si). Claim 17 In paragraph 16, a method in which the transmittance of the first material and the transmittance of the second material are both greater than 50% in exposure within the EUV range. Claim 18 delete Claim 19 delete Claim 20 A method according to claim 16, wherein the difference between the thickness of the pattern forming layer and the thickness of the phase shifter is less than 2 nm.

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