Patent Publication Number: US-2022214620-A1

Title: Reticle-masking structure, extreme ultraviolet apparatus, and method of forming the same

Description:
PRIORITY CLAIM AND CROSS-REFERENCE 
     This application is a continuation of U.S. patent application Ser. No. 17/121,588 filed on Dec. 14, 2020, entitled of “RETICLE-MASKING STRUCTURE, EXTREME ULTRAVIOLET APPARATUS, AND METHOD OF FORMING THE SAME”, which is a divisional application of U.S. patent application Ser. No. 16/589,616 filed on Oct. 1, 2019, entitled of “RETICLE-MASKING STRUCTURE, EXTREME ULTRAVIOLET APPARATUS, AND METHOD OF FORMING THE SAME”, the entire contents of all of which are hereby incorporated by reference. 
    
    
     BACKGROUND 
     The semiconductor integrated circuit (IC) industry has experienced exponential growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased. This scaling-down process generally provides benefits by increasing production efficiency and lowering associated costs while increasing the amount of functionality that can be provided in the reduced chip area. Such scaling down has also increased the complexity of processing and manufacturing ICs. 
     EUV (“extreme ultraviolet”) lithography techniques are used in the semiconductor manufacturing industry to produce feature sizes of smaller dimensions and patterns with superior resolution compared to other lithography techniques. EUV lithography techniques utilize electromagnetic radiation with wavelengths of about 13.5 nanometers, which is between visible light and x-ray on the electromagnetic spectrum. The short wavelength enables greater resolution and accurate production of smaller features. The EUV light beams are reflected from a reticle and impinge upon the substrate surface, where the EUV radiation chemically alters the exposed photoresist. Thus, particles and contaminants on the reticle significantly influence patterns of the exposed photoresist. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Aspects of the embodiments of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It should be noted that, in accordance with the standard practice in the industry, various structures are not drawn to scale. In fact, the dimensions of the various structures may be arbitrarily increased or reduced for clarity of discussion. 
         FIGS. 1 to 2  are cross-sectional diagrams of reticle-masking structures in accordance with some embodiments of the present disclosure. 
         FIG. 3  is a flowchart showing various steps of a method for forming a reticle-masking structure in accordance with some embodiments of the present disclosure. 
         FIGS. 4 to 7  are cross-sectional diagrams of a reticle-masking structure at various stages of manufacture by a method in accordance with some embodiments of the present disclosure. 
         FIGS. 8 to 10  are cross-sectional diagrams of a reticle-masking structure at various stages of manufacture by a method in accordance with some embodiments of the present disclosure. 
         FIGS. 11 to 13  are cross-sectional diagrams of a reticle-masking structure at various stages of manufacture by a method in accordance with some embodiments of the present disclosure. 
         FIGS. 14 to 17  are cross-sectional diagrams of reticle-masking structures in accordance with some embodiments of the present disclosure. 
         FIGS. 18 to 19  are bottom views of a portion of reticle-masking structures in accordance with some embodiments of the present disclosure. 
         FIG. 20  is a cross-sectional diagram of a reticle-masking structure in accordance with some embodiments of the present disclosure. 
         FIGS. 21 to 22  are cross-sectional diagrams of reticle-masking structures in accordance with some embodiments of the present disclosure. 
         FIG. 23  is a cross-sectional diagram of an extreme ultraviolet apparatus in accordance with some embodiments of the present disclosure. 
         FIGS. 24 to 25  are cross-sectional diagrams of applications of a reticle-masking structure in an apparatus in accordance with some embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of elements and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. 
     Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “over,” “upper,” “on” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly. 
     As used herein, although the terms such as “first,” “second” and “third” describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another. The terms such as “first,” “second” and “third” when used herein do not imply a sequence or order unless clearly indicated by the context. 
     Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in the respective testing measurements. Also, as used herein, the terms “substantially,” “approximately” and “about” generally mean within a value or range that can be contemplated by people having ordinary skill in the art. Alternatively, the terms “substantially,” “approximately” and “about” mean within an acceptable standard error of the mean when considered by one of ordinary skill in the art. People having ordinary skill in the art can understand that the acceptable standard error may vary according to different technologies. Other than in the operating/working examples, or unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages such as those for quantities of materials, durations of times, temperatures, operating conditions, ratios of amounts, and the likes thereof disclosed herein should be understood as modified in all instances by the terms “substantially,” “approximately” or “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the present disclosure and attached claims are approximations that can vary as desired. At the very least, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Ranges can be expressed herein as from one endpoint to another endpoint or between two endpoints. All ranges disclosed herein are inclusive of the endpoints, unless specified otherwise. 
     The advanced lithography process, method, and materials described in the current disclosure can be used in many applications, including fin-type field effect transistors (FinFETs). For example, the fins may be patterned to produce a relatively close spacing between features, for which the above disclosure is well suited. In addition, spacers used in forming fins of FinFETs can be processed according to the current disclosure. 
     A reticle-masking unit is positioned in a wafer stepper between the wafer being exposed and the light source, and its function is analogous to the aperture diaphragm in a conventional camera and selectively blocks reticle so that patterns over the reticle are not transferred to a photoresist over a wafer. It moves very rapidly and is irradiated by the light source, and fractions created during the manufacturing of the reticle-masking unit can be removed by receiving energies from the light source or the operations during the lithography. The fractions or particles fallen off from the reticle-masking unit can be a pollution to the reticle, the wafer or the chamber. Exposure operation is influenced dramatically if the fractions fall on the reticle or are close to the reticle on an optical path of the light source in the lithograph. However, formation of the fractions is almost unavoidable or difficult to completely prevent due to technical 
     The present disclosure is to provide a reticle-masking structure to mitigate the fraction or particle falling issue. In some embodiments, the reticle-masking structure can be referred to a reticle-masking (REMA) structure. The reticle-masking structure has a magnetic field to attract the fractions, and the fractions of the reticle-masking structure are very unlikely to drop off during the lithography. 
       FIG. 1  shows a reticle-masking structure  10  in accordance with some embodiments of the present disclosure. In some embodiments, the reticle-masking structure  10  includes a magnetic substrate  101  and a paramagnetic part  103 . The magnetic substrate  101  has a magnetic field. The paramagnetic part  103  is disposed on the magnetic substrate  101  and has an induced magnetic field having a direction matching that of the magnetic field of the magnetic substrate  101 . In some embodiments, the paramagnetic part  103  includes a rough surface  103   a  and a planar surface  103   b  opposite to the rough surface  103   a.  The paramagnetic part  103  includes a plurality of protrusion structures  1031 . A shape of the plurality of protrusion structures  1031  is not limited herein. In some embodiments, the plurality of protrusion structures is in a pillar shape (as shown in  FIG. 1 ), a pyramid shape, a cone shape, a frustum shape, and/or a scallop (curved) shape. The plurality of protrusion structures  1031  are proximal to the rough surface  103   a  and define the rough surface  103   a.  The magnetic substrate  101  is disposed on the planar surface  103   b  of the paramagnetic part  103 . The paramagnetic part  103  is attracted by the magnetic field of the magnetic substrate  101 , and an induced magnetic field in the direction of the magnetic field of the magnetic substrate  101  is formed in the paramagnetic part  103 . 
     In some embodiments, the paramagnetic part  103  is attached to or bonded on the magnetic substrate  101  by one or more of screwing, gluing, welding, electroplating and magnetic attraction. In some embodiments, the magnetic substrate  101  and the paramagnetic part  103  are both made of stainless steel, because stainless steel exhibits good absorptance of EUV light. In some embodiments, the paramagnetic part  103  is made of stainless steel, and the magnetic substrate  101  includes other suitable magnetic materials. In some embodiments, the paramagnetic part  103  overlaps the entire magnetic substrate  101 . In some embodiments, the paramagnetic part  103  has a width W 103  substantially equal to a width W 101  of the magnetic substrate  101 . In some embodiments, the width W 103  of the paramagnetic part  103  is greater than the width W 101  of the magnetic substrate  101  as long as the magnetic field of the magnetic substrate  101  is strong enough to form the induced magnetic field in the entire paramagnetic part  103 . 
     In some embodiments, a thickness T 101  of the magnetic substrate  101  is in a range of 1 to 20 millimeters for good attractions of the magnetic substrate  101  to the paramagnetic part  103 . In some embodiments, a thickness T 103  of the paramagnetic part  103  is in a range of 100 micrometers to 5 millimeters. In some embodiments, if the thickness T 103  is smaller than 100 micrometers, it increases the difficulty of fabrication. In some embodiments, if the thickness T 103  is greater than 5 millimeters, it increases manufacturing cost with less improvement. In some embodiments, the protrusion structures  1031  are regularly arranged, as shown in  FIG. 1 . In some embodiments, the reticle-masking structure  10  further includes an adhesion layer between the magnetic substrate  101  and the paramagnetic part  103 . In some embodiments, the reticle-masking structure  10  further includes one or more screws connecting the paramagnetic part  103  and the magnetic substrate  101 . In some embodiments, a pitch P 1031  between adjacent protrusion structures  1031  is in a range of 50 nanometers to 500 micrometers, wherein the pitch P 1031  is defined by a distance between centers of the adjacent protrusion structures  1031 , as shown in  FIG. 1 . In some embodiments with the pitch of the protrusion structures  1031  out of the range 50 nanometers to 500 micrometers, the results of light diffusion and light trapping are worse. In some embodiments, a top of the protrusion structure  1031  is in a rounded configuration instead of a rectangular configuration. 
     The paramagnetic part  103  of the reticle-masking structure  10  further includes a plurality of fractions  1032  disposed on the protrusion structures  1031 , as shown in an enlarged view of a portion of the paramagnetic part  103  shown in the dotted circle in  FIG. 1 . In some embodiments, the fractions  1032  are paramagnetic materials same as the material of the paramagnetic part  103 . In some embodiments, the fractions  1032  are pillar-like, irregular, micro-branch, or micro-bulge paramagnetic fractions. In some embodiments, the fractions  1032  are paramagnetic particles. In some embodiments, the paramagnetic particles have rounded and/or irregular configurations. In some embodiments, some of the fractions  1032  and the protrusion structure  1031  are monolithic. In some embodiments, some of the fractions  1032  attached on the protrusion structure  1031  by magnetic attraction and Van der Waals forces. In some embodiments, the plurality of fractions  1032  is not a designed structure in the manufacturing process, and a dimension of the plurality of fractions  1032  is smaller than a dimension of the protrusion structure  1031 . In some embodiments, a diameter D 1032  of the plurality of fractions  1032  is less than 1 micron. 
     In some embodiments, a material of the paramagnetic part  103  includes stainless steel having a non-face-centered cubic structure. In some embodiments, a material of the paramagnetic part  103  is selected from the group consisting of ferritic stainless steel, martensite stainless steel, precipitation-hardened stainless steel, and duplex stainless steel. In some embodiments, a material of the magnetic substrate  101  includes stainless steel, aluminum, nickel, iron, chromium, neodymium, boron, samarium, cobalt, or an alloy thereof. In some embodiments, the magnetic substrate  101  is one or more of neodymium magnet (NdFeB magnet), samarium-cobalt (SmCo) magnet, and ferrite magnet. In some embodiments, the materials of the paramagnetic part  103  and the magnetic substrate  101  are different. In some embodiments, the materials of the paramagnetic part  103  and the magnetic substrate  101  are the same. 
     In some embodiments, the magnetic substrate  101  is a permanent magnet. In some embodiments, the magnetic substrate  101  includes ferromagnetic materials with high magnetic coercivity (i.e., magnetically “hard” materials). In some embodiments, the magnetic substrate  101  is an electromagnet, including a coil of wires and a core of ferromagnetic materials with low coercivity (i.e., magnetically “soft” materials). In some embodiments, the magnetic substrate  101  is electrically connected to a power supply or a current generator. In some embodiments, the magnetic substrate  101  is electrically connected to the power supply or the current generator through a wire. 
     In some embodiments, the protrusion structures  1031  are irregularly arranged.  FIG. 2  shows a reticle-masking structure  20  in accordance with some embodiments of the present disclosure. In some embodiments, as shown in FIG,  2 , a plurality of protrusion structures  1031  of a paramagnetic part  103  having different heights and different diameters are disposed on a magnetic substrate  101 . The protrusion structures  1031  are irregularly arranged, and some of the protrusion structures  1031  are separated from adjacent protrusion structures  1031 , while others of the protrusion structures  1031  contact adjacent protrusion structures  1031 . In some embodiments, a top of the protrusion structure  1031  is in a rounded configuration instead of a rectangular configuration. The protrusion structures  1031  of the reticle-masking structure  20  are formed by a technique different from a technique used in formation of the protrusion structures  1031  of the reticle-masking structure  10 . The paramagnetic part  103  of the reticle-masking structure  20  may further include a plurality of fractions  1032  similar to the fractions  1032  of the reticle-masking structure  10 . Detailed formation of the reticle-masking structures  10  and  20  are illustrated in the following description. 
       FIG. 3  shows a flowchart of a method M 10  for forming a reticle-masking structure. The method M 10  includes steps of: (O 101 ) receiving a magnetic substrate; (O 102 ) disposing a paramagnetic part on the magnetic substrate; and (O 103 ) removing a portion of the paramagnetic part to form a rough surface of the paramagnetic part. It should be noted that the operations O 101 , O 102  and O 103  of the method M 10  may be rearranged in sequence or otherwise modified within the scope of the various aspects. 
     In order to illustrate concepts and the method M 10  of the present disclosure, various embodiments are provided below. However, it is not intended to limit the present disclosure to specific embodiments. In addition, elements, conditions or parameters illustrated in different embodiments can be combined or modified to form different combinations of embodiments as long as the elements, parameters or conditions used are not conflicted. For ease of illustration, reference numerals with similar or same functions and properties are repeatedly used in different embodiments and figures, but this is not intended to limit the present disclosure to specific embodiments. 
       FIG. 4  shows a cross-sectional diagram in accordance with some embodiments of the present disclosure and the operation O 101  of the method M 10 . A magnetic substrate  101  is received. In some embodiments, a paramagnetic part  103  is also received. In some embodiments, the paramagnetic part  103  is processed to form a rough surface  103   a  prior to disposing the paramagnetic part  103  on the magnetic substrate  101 , as shown in  FIGS. 5 to 7  and  FIGS. 8 to 10 . In some embodiments, a paramagnetic part  103  is formed on the magnetic substrate  101  prior to formation of the rough surface  103   a,  as shown in  FIGS. 11 to 13 . 
       FIGS. 5 and 6  are cross-sectional diagrams in accordance with some embodiments of the present disclosure and the operation O 103  of the method M 10 . In some embodiments, as shown in  FIG. 5 , a patterned mask layer PM is formed on the paramagnetic part  103  received in the operation O 101 , and a portion of the paramagnetic part  103  exposed through the patterned mask layer PM is removed by a process ET. In some embodiments, the process ET includes a wet etching operation. In some embodiments, the process ET includes a plasma dry etching operation. In some embodiments, the process ET includes a laser etching. In some embodiments, as shown in  FIG. 6 , the pattern of the patterned mask layer PM is transferred to the paramagnetic part  103  to form a plurality of protrusion structures  1031  and a rough surface  103   a , wherein the plurality of protrusion structures  1031  define the rough surface  103   a.  In the embodiments using the patterned mask layer PM to form the rough surface  103   a,  a pattern of the rough surface  103   a  is designed or predetermined, and the pattern of the rough surface  103   a  is regulated. In some embodiments, pitches P 1031  between adjacent protrusion structures  1031  are consistent among the plurality of protrusion structures  1031 . In some embodiments, the pitches P 1031  between adjacent protrusion structures  1031  vary among the protrusion structures  1031 . In some embodiments, a height H 1031  of the protrusion structure  1031  is smaller than a thickness T 103  of the paramagnetic part  103 . In some embodiments, the heights H 1031  of the protrusion structures  1031  are similar or substantially the same. 
     In some embodiments, branch-like, bulge-like, pillar-like or irregular residues, fractions, micro branches, and/or micro bulges of the paramagnetic part  103  are formed on the plurality of protrusion structures  1031  during removal of the portion of the paramagnetic part  103 . In some embodiments, a cleaning operation or a surface treatment is performed after the removal operation of the portion of the paramagnetic part  103 , and some of the residues, fractions, branches and/or bulges are removed by the cleaning operation. However, some of the residues fractions, branches and/or bulges are left remaining on the protrusion structures  1031 , e.g., by Van der Waals forces, or fall back onto the rough surface  103   a,  to form a plurality of fractions  1032 . 
     In some embodiments, the fractions  1032  are pillar-like, irregular, micro-branch, or micro-bulge paramagnetic fractions formed on the rough surface  103   a  during formation of the rough surface  103   a  and remained after the cleaning operation. In some embodiments, the fractions  1032  are paramagnetic particles formed from cracking of the pillar-like or irregular paramagnetic fractions, micro branches, or micro bulges during cleaning operations or surface treatments. In some embodiments, connections or adhesions between the rough surface  103   a  and fractions  1032  are tenuous, and the fractions  1032  at this stage are easily to separate from the rough surface  103   a  if applied in an EUV lithographic operation. 
       FIG. 7  is a cross-sectional diagram in accordance with some embodiments of the present disclosure and shows the operation O 102  of the method M 10  applied to the paramagnetic part  103  of  FIG. 6 . The paramagnetic part  103 , with the rough surface  103   a,  is disposed on the magnetic substrate  101  to form a reticle-masking structure  11  similar to the reticle-masking structure  10 . In some embodiments, the regular protrusion structures  1031  are configured to trap EUV radiation beams between the protrusion structures  1031 . In some embodiments, another cleaning operation is performed after disposing the paramagnetic part  103  on the magnetic substrate  101 . 
     in order to form a reticle-masking structure  21  similar to the reticle-masking structure  20 , in some embodiments, a sandblasting operation is performed instead of the forming of the patterned mask layer PM and the performing of the process ET.  FIGS. 8 to 11  are cross-sectional diagrams in accordance with some embodiments of the present disclosure, wherein the operation O 103  is performed prior to the operation O 102 , and the sandblasting operation is performed to form an irregular rough surface  103   a  of a paramagnetic part  103 . 
       FIGS. 8 to 9  are cross-sectional diagrams in accordance with sonic embodiments of the present disclosure, and show the operation O 103  of the method M 10 . The paramagnetic part  103  received in the operation O 101  is subjected to a sandblasting operation SB. Particles hit a top surface of the paramagnetic part  103  to form the rough surface  103   a  with an irregular pattern. A plurality of protrusion structures  1031  with an irregular arrangement may be formed, wherein the protrusion structures  1031  can include different heights, different widths, and different shapes. In some embodiments, the protrusion structures  1031  include a protrusion structure  1031   a  and a protrusion structure  1031   b  adjacent to each other. The protrusion structure  1031   a  has a height H 1031   a  and a width W 1031   a,  and the protrusion structure  1031   b  has a height H 1031   b  and a width W 1031   b.  In some embodiments, the protrusion structure  1031   a  and the protrusion structure  1031   b  are side by side and in contact with each other. In some embodiments, the height H 1031   a  of the protrusion structure  1031   a  is less than the height H 1031   b  of the protrusion structure  1031   b . In some embodiments, the width W 1031   a  of the protrusion structure  1031   a  is less than the width W 1031   b  of the protrusion structure  1031   b.  In some embodiments, configurations of the protrusion structures  1031  are different, as shown in an enlarged view of a portion of the paramagnetic part  103  as shown on the left side of  FIG. 9 . In some embodiments, heights of the protrusion structures  1031  are smaller than a thickness T 103  of the paramagnetic part  103 . 
       FIG. 10  is a cross-sectional diagram in accordance with some embodiments of the present disclosure and shows the operation O 102  of the method M 10  applied to the paramagnetic part  103  of  FIG. 9 . The paramagnetic part  103 , with the irregular rough surface  103   a,  is disposed on the magnetic substrate  101  to form the reticle-masking structure  21  similar to the reticle-masking structure  20 . in some embodiments, the irregular protrusion structures  1031  are configured to diffuse EUV radiation beams. 
     In some embodiments, the operation O 102  is performed prior to the operation O 103 . As shown in  FIG. 11 , after receiving a magnetic substrate  101 , as in the operation O 101 , the operation O 102  is performed. A paramagnetic part  103  is disposed on the magnetic substrate  101 . In some embodiments, the paramagnetic part  103  includes a planar surface  103   b  (bottom surface), and the magnetic substrate  101  is proximal to the planar surface  103   b  of the paramagnetic part  103 . In some embodiments, the paramagnetic part  103  is received as illustrated in  FIG. 4  and relevant descriptions thereof, and then the paramagnetic part  103  is disposed on the magnetic substrate  101 . In some embodiments, the paramagnetic part  103  is attached to or bonded on the magnetic substrate  101  using one or more screws, an adhesive layer or a glue layer. In sonic embodiments, the paramagnetic part  103  is attached to or bonded on the magnetic substrate  101  by welding. In some embodiments, the paramagnetic part  103  is attached to the magnetic substrate  101  by magnetic attraction. In some embodiments, the paramagnetic part  103  is formed on the magnetic substrate  101  by electroplating or deposition. 
     Referring to  FIGS. 12 to 13 , the operation O 103  is performed on the structure shown in  FIG. 11 . In some embodiments, similar to the operation as illustrated in  FIG. 5  and relevant descriptions thereof, a patterned mask layer PM is formed and a process ET is performed to form a rough surface  103   a  of the paramagnetic part  103 . A reticle-masking structure  12  is thereby formed, as shown in  FIG. 13 . In some embodiments, a sandblasting operation SB, as illustrated in  FIG. 8  and described in relevant paragraphs, is performed to form a rough surface  103   a  with an irregular pattern. In some embodiments, some of protrusion structures  1031  have a rounded top, as shown in  FIG. 13 . In some embodiments, some of the protrusion structures  1031  have relatively planar tops, and configurations of the protrusion structures  1031  are not limited herein. In sonic embodiments, heights H 1031  of the protrusion structures  103  are smaller than a thickness T 103  of the paramagnetic part  103 . In some embodiments, the fractions  1032  become a plurality of magnets after the paramagnetic part  103  is attached to the magnetic substrate  101 . The fractions  1032  may temporarily include magnetic poles with different polarities after the fractions  1032  separate from the rough surface during the EUV operation. If the magnetic substrate  101  is exposed, it is possible for the separated fraction  1032  to be repelled from the magnetic substrate when a magnetic pole of the fraction  1032  having a same polarity as the exposed portion of the magnetic substrate  101  comes into contact with or proximity to the magnetic substrate  101 . In some embodiments, a top surface  101   a  of the magnetic substrate  101  is attached to and entirely covered by the planar surface  103   b  of the paramagnetic part  103 . 
     The magnetic substrate  101  provides a magnetic field strong enough to create an induced magnetic field in the paramagnetic part  103 , wherein the induced magnetic field is strong enough to attract separated fractions  1032 . In some embodiments, strength of the magnetic field of the magnetic substrate depends on a thickness of the paramagnetic part  103  and on a quantity of protrusion structures  1031  of the paramagnetic part  103 . In some embodiments, the strength of the magnetic field is greater than 1000 G. In some embodiments, the magnetic substrate  101  includes one magnet. In some embodiments, the magnetic substrate  101  includes multiple magnets, wherein one magnet includes one south magnetic pole and one north magnetic pole. In some embodiment, a quantity of protrusion structures  1031  of the paramagnetic part  103  covered by one magnetic field depend on strength of the magnetic field and difficulty of fabricating the magnetic substrate  101  with a certain arrangement of the magnetic field(s). In some embodiments, a number of the protrusion structures  1031  of the paramagnetic part  103  covered by one magnetic field is in a range of 6-6000. 
       FIGS. 14 to 17  and  FIGS. 20 to 22  are cross-sectional views and.  FIGS. 18 to 19  are bottom views of different reticle-masking structures in accordance with different embodiments of the present disclosure. In the embodiments shown in  FIGS. 14 to 17  and  FIGS. 20 to 22 , a rough surface  103   a  of a paramagnetic part  103  having a designed pattern is used for a purpose of illustration, but the illustration is not intended to limit the present disclosure. 
     Referring to  FIG. 14 , in accordance with some embodiments of the present disclosure, a magnetic substrate  101  of a reticle-masking structure  30  includes one magnet. The lines with arrows illustrate magnetic field lines and the directions of the magnetic field. A paramagnetic part  103  is within the magnetic field of the magnetic substrate  101 , and a magnetic field is induced with a direction matching that of the magnetic field of the magnetic substrate  101 . The direction of the magnetic field of the magnetic substrate  101  is from the north magnetic pole to the south magnetic pole. In some embodiments, an arrangement of a north magnetic pole (hereinafter “N pole”) and a south magnetic pole (hereinafter “S pole”) of the magnet of the magnetic substrate  101  is substantially parallel to a planar surface  103   a  of the paramagnetic part  103 . In some embodiments, the arrangement of the N pole and the S pole is substantially parallel to the lengthwise direction of the paramagnetic part  103 . In some embodiments, both the N pole and the S pole are in contact with the paramagnetic part  103 . For ease of illustration, magnetic field lines of magnetic substrates  101  in the embodiments shown in  FIGS. 15 to 20  are simplified. 
     Referring to  FIG. 15 , in accordance with some embodiments of the present disclosure, a magnetic substrate  101  of a reticle-masking structure  31  also includes one magnet, but the direction of the arrangement of the N pole and the S pole in the reticle-masking structure  31  is different from that in the reticle-masking structure  30 . In some embodiments, only one of the N pole and the S pole is in contact with the paramagnetic part  103 . In some embodiments, the arrangement of the N pole and the S pole is substantially perpendicular to the planar surface  103   a  of the paramagnetic part  103 . In some embodiments, the arrangement of the N pole and the S pole is substantially perpendicular to the lengthwise direction of the paramagnetic part  103 . In some embodiment, a sidewall S 1011  of an edge magnet  1011  is aligned with a sidewall S 103  of the paramagnetic part  103 . 
     Referring to  FIG. 16 , in accordance with some embodiments of the present disclosure, a magnetic substrate  101  of a reticle-masking structure  32  includes a plurality of magnets  1011 . A paramagnetic part  103  is within magnetic fields of the magnetic substrate  101 , and a plurality of magnetic fields is induced with directions matching those of the magnetic fields of the magnets  1011  of the magnetic substrate  101 . In some embodiments, each of the magnets  1011  contacts an adjacent magnet  1011 . In some embodiments, an N pole of a magnet  1011  contacts an S pole of the adjacent magnet  1011 . In some embodiments, a width W 101  of the magnetic substrate  101  is less than a width W 103  of the paramagnetic part  103 . In some embodiments, an arrangement of the N pole and the S pole of each of the magnets  1011  is substantially parallel to a planar surface  103   b  of the paramagnetic part  103 . In some embodiments, the arrangement of the N pole and the S pole of each of the magnets  1011  is substantially parallel to a lengthwise direction of the paramagnetic part  103 . In some embodiment, a sidewall S 1011  of an edge magnet  1011  is not aligned with a sidewall S 103  of the paramagnetic part  103  depends on strengths of the magnetic fields of the substrate  101 . In some embodiments, all magnets  1011  are within an area of the planar surface  103   b  of the paramagnetic part  103 . 
     Referring to  FIG. 17 , a magnetic substrate  101  of a reticle-masking structure  33  includes a plurality of magnets  1011 , similar to the magnetic substrate  101  of the reticle-masking structure  32 . A difference between the reticle-masking structure  33  and the reticle-masking structure  32  is that the magnets  1011  of the reticle-masking structure  33  are separated from each other. In some embodiment, the magnets  1011  are embedded in or bonded by a material structure  1012  to make the magnets  1011  and the material structure  1012  as a one-piece magnetic substrate  101 . in some embodiments, a size and shape of the material structure  1012  is not limited herein as long as the material structure  1012  can connect all the magnets  1011  to form a plate-like substrate. In some embodiments, the material structure  1012  is made of dielectric materials without blocking the magnetic attractions of the magnets. Magnetic fields between the magnets  1011  induce magnetic fields in the paramagnetic part  103 . 
     A configuration of the magnets  1011  is not limited herein. According to some embodiments,  FIGS. 18 and 19  are bottom views of a portion of the reticle-masking structure  33  in accordance with different embodiments. In some embodiments as shown in  FIG. 18 , the magnets  1011  are all in a strip or a rectangular configuration, and the magnets  1011  are arranged parallel to each other. The plurality of magnets  1011  are arranged along a direction perpendicular to a lengthwise direction of each of the magnets. In some embodiments, the plurality of magnets  1011  extends along X direction while an extending direction of a single magnet  1011  is along Y direction According to some embodiments,  FIG. 17  shows the reticle-masking structure  33  from a cross-sectional perspective taken along a line A-A′ in  FIG. 18 . In some embodiments, each of the magnets  1011  is smaller than the magnet  1011  shown in  FIG. 18 , and an arrangement of the magnets  1011  or a pattern of the magnetic substrate  101  is in a grid array, as shown in  FIG. 19 . The plurality of magnets  1011  is arranged to extend in both the X direction and the Y direction. According to some embodiments,  FIG. 17  shows the reticle-masking structure  33  from a cross-sectional perspective taken along a line B-B′ in  FIG. 19 . According to some embodiments,  FIG. 17  shows the reticle-masking structure  33  from a cross-sectional perspective taken along a line C-C′ in  FIG. 19 . In some embodiments as shown in  FIGS. 17-19 , the material structure  1012  is entirely covered by and smaller than the paramagnetic part  103 . However, the present disclosure is not limited herein. In some embodiments, material structure  1012  is entirely overlapped and substantially the same size as the paramagnetic part  103 . 
       FIG. 20  shows a magnetic substrate  101  of a reticle-masking structure  34  similar to the magnetic substrate  101  of the reticle-masking structure  33 . A difference between the reticle-masking structure  34  and the reticle-masking structure  33  is that the arrangement of the N pole and the S pole of each magnet  1011  is substantially perpendicular to the rough surface  103   a  of the paramagnetic part  103 . In some embodiments, the arrangement of the N pole and the S pole of each magnet  1011  is substantially perpendicular to a lengthwise direction of the paramagnetic part  103 . In some embodiments, magnetic field directions of adjacent magnets  1011  are opposite. 
     In some embodiments, the magnets  1011  or the magnetic substrate  101  on the paramagnetic part  103  of the reticle-masking structure  34  as shown in  20  are arranged in a plurality of parallel strips similar to the bottom view shown in  FIG. 18 . In some embodiments, the magnets  1011  or the magnetic substrate  101  on the paramagnetic part  103  of the reticle-masking structure  34  as shown in  FIG. 20  are arranged as a grid array similar to the bottom view shown in  FIG. 19 . 
       FIG. 21  shows a magnetic substrate  101  of a reticle-masking structure  35  similar to the magnetic substrate  101  of the reticle-masking structure  34 . A difference between the reticle-masking structure  35  and the reticle-masking structure  34  is that in the reticle-masking structure  35 , magnets  1011  are in contact with adjacent magnets  1011  instead of being separated from each other. In some embodiments, the N poles and the S poles of the magnets  1011  are alternately arranged. Magnetic field lines of the reticle-masking structure  35  are similar to those of the reticle-masking structure  34  shown in  FIG. 20 , and for ease of illustration, magnetic field lines are omitted in  FIG. 23 . 
       FIG. 22  shows a magnetic substrate  101  of a reticle-masking structure  36  similar to the magnetic substrate  101  of the reticle-masking structure  35 . A difference between the reticle-masking, structure  36  and the reticle-masking structure  35  is that in the reticle-masking structure  36 , same polarities of adjacent magnets  1011  are aligned. In some embodiments, the N poles of the magnets  1011  are in contact with the paramagnetic part  103  and an N pole of a magnet  1011  is in contact a N pole of an adjacent magnets  1011 , as shown in  FIG. 22 . In some embodiments, the S poles of the magnets  1011  are in contact with the paramagnetic part  103 . Magnetic field lines of the reticle-masking structure  36  are similar to those of the reticle-masking structure  31  shown in  FIG. 15 , and for ease of illustration, magnetic field lines are omitted in  FIG. 24 . 
     In some embodiments of the present disclosure, an EUV apparatus is provided including one of the above illustrated reticle-masking structures. Referring to  FIG. 23 , an EUV apparatus A 10  in accordance with some embodiments of the present disclosure is provided. The EUV apparatus A 10  includes a radiation source  210 , a reticle-masking structure  10 , and a reticle  220 . In some embodiments, the radiation source  210  is configured to generate a radiation beam  211  (e.g., EUV rays). In some embodiments, the reticle-masking structure  10  is replaced by one of the above-described reticle-masking structures  11 ,  12 ,  20 ,  21 , or  30  to  36 . The reticle-masking structure  10  is used herein for a purpose of illustration, but is not intended to limit the present disclosure. In some embodiments, the reticle-masking structure is configured to diffuse a portion of the radiation beam  211 . In some embodiments, the reticle  220  is configured to reflect the remaining portion of the radiation beam after the diffusion of the portion of the radiation beam in order to transfer a pattern of the reticle  220  onto a wafer  300 . 
     In some embodiments, the apparatus A 10  further includes an optical collector  212 , configured to concentrate the radiation beam  211  generated by the radiation source  210  onto the reticle  220 . In some embodiments, the apparatus A 10  further includes an optical system  240 , configured to receive the radiation beam  211  from the radiation source  210  and reflect the radiation beam  211  onto the reticle  220  and then onto the wafer  300 . In some embodiments, the optical system  240  includes a plurality of mirrors  241 , configured to reflect the radiation beam  211  from the radiation source  210  toward the reticle  220 . In some embodiments, the plurality of mirrors  241  are also configured to reduce a size of the pattern of the reticle  220  and reflect the radiation beam  211  onto the wafer  300 . In some embodiments, the plurality of mirrors  241  include a plurality of plane mirrors  241   a  to reflect the radiation beam  211  from the radiation source  210  toward the reticle  220 . In some embodiments, the plurality of mirrors  241  include a plurality of concave mirrors  241   b  configured to concentrate the radiation beam  211  reflected by the reticle  220  in order to reduce the size of the pattern of the reticle  220 . 
     In some embodiments, the apparatus A 10  further includes a reticle stage  230  configured to load or carry the reticle  220 . In some embodiments, the apparatus A 10  further includes a masking carrier  231 , configured to load or carry the reticle-masking structure  10 . In some embodiments, the masking carrier  231  includes a motor (not shown), configured to adjust a position of the reticle-masking structure  10 . In some embodiments, the apparatus A 10  further includes a wafer stage  232 , configured to load or carry the wafer  300 . In some embodiments, the wafer stage  232  includes a motor (not shown), configured to adjust a position of the wafer  300 . 
     In order to further illustrate functions of the apparatus and the reticle-masking structure of the present disclosure,  FIGS. 24 to 25  show an enlarged view of a portion (indicated with a dashed-line box in  FIG. 23 ) of the apparatus A 10  during an EUV lithographic operation performed by the apparatus A 10  in accordance with different embodiments. 
     In some embodiments, as shown in  FIG. 24 , the radiation beam  211  from the radiation source  210  includes a first portion  2111  and a second portion  2112 . The first portion  2111  is a portion of the radiation beam  211  that is to be prevented from irradiating the wafer  300 . The first portion  2111  is radiated onto the rough surface  103   a  of the reticle-masking structure  10  and is diffused by the rough surface  103   a.  In some embodiments, during a lithographic operation, the radiation beam  211  (e.g., EUV light) gives energy to the fractions  1032 , causing the fractions  1032  to separate from the rough surface  103   a,  after the reticle-masking structure  10  being irradiated by the first portion  2111  of the radiation beam  211 . In some embodiments, the separated fractions  1032  are attracted back to the rough surface  103   a  by the magnetic forces of the magnetic substrate  101  and the paramagnetic part  103 . In some embodiments, the fractions  1032  are attached to the rough surface  103   a  of the paramagnetic part  103  by magnetic attraction. In some embodiments, positions of the fractions  1032  on the rough surface  103   a  changes during the EUV lithographic operation. In some embodiments, the fractions  1032  are remained steadily on the rough surface  103   a  of the paramagnetic part  103  by strong magnetic attraction during the EUV lithographic operation. 
     The second portion  2112  of the radiation beam  211  is reflected by the reticle  220 . In some embodiments, the reticle  220  includes a pattern  221 , and the pattern  221  includes an edge pattern  221   a  and a chip pattern  221   b.  In some embodiments, the second portion  2112  is reflected by a portion of the reticle  220  having the chip pattern  221   b  and at least a portion of the edge pattern  221   a.  In some embodiments, an image of the edge pattern  221   a  is substantially transferred to a scribe line region of the wafer  300 . In some embodiments, a first sub-portion  211   a  of the second portion  2112  of the radiation beam  211  is reflected by a portion of the reticle  220  having the edge pattern  221   a.  In some embodiments, the chip pattern  221   b  may correspond to a layout pattern constituting integrated circuits. In some embodiments, an image of the chip pattern  221   b  is transferred to a die region of the wafer  300 . In some embodiments, a second sub-portion  211   b  of the second portion  2112  of the radiation beam  211  is reflected by a portion of the reticle  220  having the chip pattern  221   b.    
     In some embodiments, as shown in  FIG. 25 , similar to the embodiments shown in  FIG. 26 , the radiation beam  211  from the radiation source  210  includes a first portion  2111  and a second portion  2112 , wherein the rough surface  103   a  of the reticle-masking structure  10  helps to diffuses the first portion  2111  so that the reflection of the first portion  2111  is reduced. The second portion  2112  is reflected by the reticle  220 , particularly by the chip pattern  221   b.  A difference between the embodiments shown in  FIG. 27  and the embodiments shown in  FIG. 24  is that, in the embodiments shown in  FIG. 27 , the second portion  2112  is substantially reflected by a portion of the reticle  220  having substantially the chip pattern  221   b.  In some embodiments, the radiation beam  211  further includes a penumbra portion  2113  after the radiation beam  211  is radiated onto the reticle-masking structure  10 . In some embodiments, the penumbra portion  2113  is projected onto a portion of the reticle  220  having the edge pattern  221   a . In some embodiments, a light intensity of the penumbra portion  2113  is very low, and the penumbra portion  2113  is not able to transfer an image of the edge pattern  221   a  onto the wafer  300 . In some embodiments, the penumbra portion  2113  is reflected by the portion of the reticle  220  having the edge pattern  221   a.    
     Some embodiments of the present disclosure provide a reticle-masking structure. The reticle-masking structure includes a magnetic substrate and a paramagnetic part disposed on the magnetic substrate. The paramagnetic part includes a plurality of fractions disposed on a plurality of protrusion structures. In some embodiments, the plurality of fractions are irregularly arranged. 
     Some embodiments of the present disclosure provide a method for forming a reticle-masking structure. The method includes: receiving a magnetic substrate; disposing a paramagnetic part on the magnetic substrate; removing a portion of the paramagnetic part to form a rough surface; and forming a plurality of fractions on the rough surface. In some embodiments, the plurality of fractions are irregularly arranged. 
     Some embodiments of the present disclosure provide an extreme ultraviolet apparatus. The extreme ultraviolet apparatus includes: a radiation source, a reticle-masking structure and a reticle. The radiation source generates a radiation beam, and the reticle-masking structure is configured to diffuse the radiation beam, The reticle-masking structure includes a magnetic substrate and a paramagnetic part disposed on the magnetic substrate. The paramagnetic part includes a plurality of fractions irregularly arranged on a surface of the paramagnetic part. The reticle is configured to reflect the radiation beam. 
     The foregoing outlines structures of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled 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 advantages of the embodiments introduced 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 herein without departing from the spirit and scope of the present disclosure.