Systems and methods for cleaning extreme ultraviolet masks

Abstract

A system and method for cleaning an extreme ultraviolet mask, an EUV lithography system cleans debris from an EUV mask. The system includes a cleaning electrode positioned adjacent to the EUV mask. The system includes a voltage source that assists in attracting debris from the EUV mask to the cleaning electrode by applying voltages of alternating polarity to the cleaning electrode.

Description

Technical Field

[0001] This disclosure relates to a system and method for cleaning extreme ultraviolet (EUV) shields. Background Technology

[0002] The demand for increased computing power in electronic devices, including smartphones, tablets, desktop computers, laptops, and many other types of electronic devices, is constantly growing. Integrated circuits provide this computing power to these devices. One way to increase the computing power of integrated circuits is to increase the number of transistors and other integrated circuit features in a given area of ​​semiconductor substrate.

[0003] Feature portions in integrated circuits are created using lithography. Traditional lithography involves creating a mask that outlines the shape of the feature to be formed on the integrated circuit die. A lithography light source illuminates the integrated circuit die through the mask. The size of a feature that can be produced by lithography on an integrated circuit die is partially limited at the lower end by the wavelength of the light generated by the lithography light source. Smaller wavelengths of light can produce smaller feature sizes.

[0004] Because extreme ultraviolet (EUV) light has a relatively short wavelength, it is used to produce extremely small features. For example, EUV light is typically generated by irradiating a droplet of selected material with a laser beam. The energy from the laser beam causes the droplet to enter a plasma state. In the plasma state, the droplet emits EUV light. The EUV light is directed to a collector with an elliptical or parabolic surface. The collector reflects the EUV light to a scanner. The scanner then irradiates a target with EUV light via a photomask. However, because the feature sizes to be transferred from the photomask to the integrated circuit are very small, even very small particles or debris falling onto the surface of the photomask can damage the lithography process, and the resulting integrated circuit will not function properly. Summary of the Invention

[0005] According to some embodiments of this disclosure, a method for cleaning an extreme ultraviolet (EUV) mask includes the following steps: positioning a cleaning electrode near an exposure surface of a photomask; applying a voltage having a first polarity to the cleaning electrode; and switching the voltage from the first polarity to a second polarity opposite to the first polarity.

[0006] According to some embodiments of this disclosure, a method for cleaning an extreme ultraviolet (EUV) mask includes the following steps: performing an UV lithography process using an UV photomask; after performing the UV lithography process, positioning a cleaning electrode near an exposure surface of the UV photomask; and cleaning debris on the exposure surface by using the cleaning electrode to generate an electric field with alternating polarities.

[0007] According to some embodiments of this disclosure, an extreme ultraviolet (EUV) mask cleaning system includes: a cleaning electrode; a debris trapping membrane supported near and spaced apart from the cleaning electrode; and a voltage source for applying an alternating polarity voltage to the cleaning electrode when the cleaning electrode is adjacent to a photomask to attract debris from the photomask to the debris trapping membrane, wherein the debris trapping membrane is located between the photomask and the cleaning electrode. Attached Figure Description

[0008] The various aspects of this disclosure can be best understood in conjunction with the accompanying drawings and the following detailed description. Note that, in accordance with industry standard practice, the features are not drawn to scale. In fact, for clarity of discussion, the dimensions of the features may be arbitrarily increased or decreased.

[0009] Figure 1 A block diagram of an EUV lithography system according to some embodiments;

[0010] Figure 2A A side view of a photomask cleaning system according to some embodiments;

[0011] Figure 2B A top view of the cleaning electrodes of a photomask cleaning system according to some embodiments;

[0012] Figures 3A to 3E A view of a photomask cleaning system and a photomask according to some embodiments;

[0013] Figures 4A to 4D A graph relating to the voltage applied to the cleaning electrodes of a photomask cleaning system according to some embodiments;

[0014] Figure 5 A cross-sectional view of an EUV photomask according to some embodiments;

[0015] Figure 6 A top view of an EUV photomask according to some embodiments;

[0016] Figure 7 A perspective view of an EUV photomask according to some embodiments;

[0017] Figure 8 This is a flowchart of a method for cleaning an EUV photomask according to some embodiments;

[0018] Figure 9 This is a flowchart of a method for cleaning an EUV photomask according to some embodiments.

[0019] [Symbol Explanation]

[0020] 100: EUV lithography system

[0021] 102: EUV Generator

[0022] 104: Scanner

[0023] 106: Light Mask

[0024] 107: Wafer

[0025] 108: Scanner Optical Components

[0026] 110: EUV light

[0027] 112: Robotic Arm

[0028] 114: EUV memory

[0029] 117: Photomask Analyzer

[0030] 118: Photomask Cleaning System

[0031] 120: Cleaning Electrode

[0032] 122: Voltage source

[0033] 124: Support pin

[0034] 126: Membrane

[0035] 128: Top surface

[0036] 130: Chuck

[0037] 132: Exposure

[0038] 142, 144, 146, 148, 150, 152: Debris particles

[0039] 160:Substrate

[0040] 162: Back surface

[0041] 164: Multi-layered reflection

[0042] 165: Buffer layer

[0043] 166: Absorption layer

[0044] 168: First Absorption Layer

[0045] 170: Second absorption layer

[0046] 172: Trench

[0047] 174, 176: Charged debris particles

[0048] 178: Debris

[0049] 180: Pattern

[0050] 181: Notch

[0051] 182: Target

[0052] 183: Barcode

[0053] 402, 404, 406: Voltage waveforms

[0054] 408: Chart

[0055] 800: Method

[0056] 802, 804, 806: Steps

[0057] 900: Method

[0058] 902, 904, 906: Steps

[0059] d: distance

[0060] D1: First dimension

[0061] D2: Second size

[0062] Q: Charge

[0063] t0, t1, t2: Time

[0064] Vn: Negative voltage polarity

[0065] Vp: Positive voltage

[0066] X: X-axis

[0067] Y: Y-axis

[0068] Z: Z-axis Detailed Implementation

[0069] The following disclosure provides numerous different embodiments or instances for implementing various features of the provided subject matter. Specific examples of elements and arrangements described below are used to simplify this disclosure. Of course, these are merely examples and are not intended to be limiting. For example, the following description of forming a first feature above or on a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which an additional feature is formed between the first and second features such that the first and second features do not need to be in direct contact. Furthermore, element symbols or letters may be repeated in various instances of this disclosure. This repetition is for simplicity and clarity and does not in itself specify a relationship between the various embodiments or configurations discussed.

[0070] Furthermore, for ease of description, spatial relative terms such as “below,” “under,” “below,” “above,” and “above” may be used herein to describe the relationship between one element or feature and another, as shown in the figures. In addition to the orientations shown in the figures, the spatial relative terms are intended to cover different orientations of the device during use or operation. The device may be oriented in other ways (rotated 90 degrees or otherwise), and the spatial relative descriptive terms used herein may be interpreted accordingly.

[0071] In the following description, certain specific details are set forth in order to provide a thorough understanding of various embodiments of this disclosure. However, those skilled in the art will understand that this disclosure can be practiced without these specific details. In other instances, well-known structures associated with electronic components and manufacturing techniques have not been described in detail to avoid unnecessarily obscuring the embodiments of this disclosure.

[0072] Unless the context otherwise requires, throughout the specification and claims, the phrase “comprising” and its variations shall be interpreted in an open and inclusive sense, that is, “including, but not limited to”.

[0073] The use of ordinal numbers such as first, second, and third does not necessarily imply ordering, but only distinguishes multiple instances of an action or structure.

[0074] Throughout this specification, references to "some embodiments" or "embodiments" mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. Therefore, the phrases "in some embodiments" or "in an embodiment" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, in one or more embodiments, particular features, structures, or characteristics may be combined in any suitable manner.

[0075] As used in this specification and claims, the singular forms “a” and “the” include multiple objects unless expressly specified herein. It should also be noted that, unless clearly stated otherwise, the term “or” is generally used to include “and / or”.

[0076] The embodiments disclosed herein offer numerous benefits to EUV lithography systems. These embodiments effectively and efficiently remove particles and other contaminants from EUV photomasks. After the EUV lithography process, the photomask is transferred to a photomask cleaning system. The photomask cleaning system includes a cleaning electrode. The exposed surface of the photomask is positioned facing the cleaning electrode at a short distance. A voltage of first polarity is applied to the cleaning electrode. Debris particles carrying a net charge of a second polarity opposite to the first polarity are attracted from the photomask to the cleaning electrode and captured by a film located between the cleaning electrode and the photomask. Then, the polarity of the voltage applied to the cleaning electrode is reversed to the second polarity. Debris particles carrying a net charge of the first polarity are then attracted to the cleaning electrode and captured by the film. This process can be repeated multiple times to completely remove all debris particles. As a result, the EUV lithography process is not interrupted or damaged by debris on the exposed surface of the photomask. Furthermore, the expensive and time-consuming photomask cleaning process can be avoided, contributing to the efficient and effective process described herein. Wafer yield is improved, and there is no need to replace expensive photomasks.

[0077] Figure 1 This is a block diagram of an EUV lithography system 100 according to some embodiments. The EUV lithography system includes an EUV generator 102, a scanner (EUV scanner) 104, and a photomask (EUV photomask) 106 located in the scanner 104. The EUV generator 102, scanner 104, and photomask 106 perform lithography processes on a wafer 107. System 100 also includes a photomask cleaning system 118. As will be described in more detail below, the photomask cleaning system 118 helps remove debris particles from the photomask 106 in an effective and efficient cleaning process.

[0078] Figure 1 The image shows the photomask 106 at various locations within the EUV lithography system 100. This illustrates the different positions where the photomask 106 can be located at different stages of its use.

[0079] EUV generator 102 generates EUV light 110. As used herein, the terms "EUV light" and "EUV radiation" are used interchangeably. In some embodiments, EUV light 110 has a wavelength between 10 nm and 15 nm. In one example, EUV light 110 has a center wavelength of 13.5 nm. In lithography, one of the factors affecting the feature size that can be formed in a wafer is the wavelength of the light used in the lithography process. Because EUV light has a very small wavelength, very small features can be defined on wafer 107 using EUV light. Different EUV generation processes can provide EUV light with different wavelength ranges and different center wavelengths. Therefore, without departing from the scope of this disclosure, EUV light 110 can have different wavelength ranges and different center wavelengths than those described above.

[0080] In some embodiments, the EUV generator 102 is a laser-produced plasma (LPP) EUV generation system. The lithography system 100 includes a laser, a droplet generator, and a droplet receiver. The laser, the collector mirror, and the droplet generator cooperate to generate EUV radiation within the EUV generator 102.

[0081] A droplet generator produces and outputs a stream of droplets. The droplets may include tin, but other materials may be used without departing from the scope of this disclosure. The droplets move at high speed toward a droplet receiver. In some embodiments, the droplet generator produces 40,000 to 100,000 droplets per second. The initial velocity of the droplets is between 60 m / s and 200 m / s. The diameter of the droplets is between 10 μm and 200 μm. Without departing from the scope of this disclosure, the droplet generator may produce different numbers of droplets per second than those described above. Without departing from the scope of this disclosure, the droplet generator may also produce droplets with different initial velocities and diameters than those described above.

[0082] The laser is located behind the collector mirror. During operation, the laser outputs laser pulses. These pulses are focused onto points along the droplet's path from the droplet generator to the droplet receiver. Each laser pulse is received by the droplet. When the droplet receives a laser pulse, the energy of the pulse generates a high-energy plasma within the droplet. This high-energy plasma outputs EUV light.

[0083] In some embodiments, the laser is a carbon dioxide (CO2) laser. A CO2 laser emits radiation or laser light with wavelengths concentrated around 9.4 μm or 10.6 μm. Without departing from the scope of this disclosure, the laser may include lasers other than carbon dioxide lasers and may output radiation with wavelengths different from those described above.

[0084] In some embodiments, the laser irradiates each droplet with two pulses. The first pulse flattens the droplet into a disk shape. The second pulse causes the droplet to form a high-temperature plasma. The second pulse is significantly more powerful than the first pulse. The laser and droplet generator are calibrated so that the laser emits paired pulses, thereby irradiating each droplet with a pair of pulses. For example, if the droplet generator outputs 50,000 droplets per second, the laser will output 50,000 pairs of pulses per second. Without departing from the scope of this disclosure, the laser may irradiate the droplets in a manner different from that described above. For example, the laser may irradiate each droplet with a single pulse or more than two pulses. Moreover, the primary laser described herein can not only flatten the droplets into a disk shape, but also allow them to form a mist or vapor state.

[0085] In some embodiments, the droplet is tin. When the tin droplet transforms into plasma, it emits EUV light 110 with wavelengths concentrated between 10 nm and 15 nm. More specifically, in some embodiments, the tin plasma emits EUV radiation with a center wavelength of 13.5 nm. These wavelengths correspond to EUV radiation. Materials other than tin may be used for the droplet without departing from the scope of this disclosure. Such other materials may produce EUV radiation with wavelengths different from those described above without departing from the scope of this disclosure.

[0086] In some embodiments, the light 110 emitted by the droplet is randomly scattered in many directions. The lithography system 100 uses a collector mirror to collect the scattered EUV light 110 from the plasma and outputs the EUV light to the scanner 104.

[0087] Scanner 104 includes scanner optics 108. Scanner optics 108 includes a series of optical adjustment devices to guide EUV light 110 to photomask 106. Scanner optics 108 may include refractive optics, such as lenses or lens systems with multiple lenses (zone plates). Scanner optics 108 may include reflective optics, such as a single mirror or a mirror system with multiple mirrors. Scanner optics 108 guides ultraviolet light 110 from EUV generator 102 to photomask 106. Further details regarding photomask 106 are provided below.

[0088] Other optical features of the ultraviolet light 110 reflected from the photomask 106 back to the scanner optics 108. In some embodiments, the scanner optics 108 includes a projection optics box. The projection optics box may have refractive optics, reflective optics, or a combination of refractive and reflective optics. The projection optics box may include a magnification of less than 1, thereby reducing patterned images included in the EUV light 110 reflected from the photomask 106. The projection optics box guides the EUV light onto the wafer 107.

[0089] EUV light 110 includes a pattern from photomask 106. Specifically, photomask 106 includes a pattern to be defined in wafer 107. After EUV light 110 is reflected from photomask 106, EUV light 110 contains the pattern of photomask 106.

[0090] A photoresist layer is typically applied to the target during extreme ultraviolet lithography. The photoresist helps to pattern the surface of the semiconductor wafer according to the pattern of the photomask 106.

[0091] A projection optics box focuses extreme ultraviolet (EUV) light onto wafer 107. The EUV light irradiates a photoresist with a pattern corresponding to the pattern of photomask 106. The exposed portion of the photoresist undergoes a chemical change, thereby removing a portion of the photoresist. This pattern leaves the photoresist on the surface of the semiconductor wafer in the pattern of photomask 106. Etching, thin film deposition, and / or doping processes are performed in the presence of the patterned photoresist.

[0092] Typically, a large number of photomasks are used during the fabrication of a single semiconductor wafer. Each photomask has a specific pattern corresponding to a semiconductor process. One or more etching, deposition, or doping processes are performed based on each photomask.

[0093] If defects exist in photomask 106, corresponding defects may occur in the various semiconductor processes associated with photomask 106. Defects propagating from photomask 106 to the processes can cause semiconductor devices to malfunction. Given the significant time, expensive tools, and costly materials required to manufacture each semiconductor device, a malfunctioning device represents a substantial waste of resources. Therefore, minimizing defects in photomask 106 is beneficial. Furthermore, replacing damaged or contaminated photomasks can be extremely expensive.

[0094] To reduce or prevent defects in semiconductor manufacturing processes caused by debris on the photomask 106, the EUV system 100 includes a photomask cleaning system 118. The photomask cleaning system 118 removes debris from the photomask 106. As described in more detail below, the photomask cleaning system 118 is highly effective at cleaning debris from the photomask 106. Furthermore, the photomask cleaning system 118 is significantly less expensive than other solutions used for cleaning photomasks.

[0095] Most or all of the debris falling on the surface of photomask 106 carries a net charge. The debris typically includes particles from the environment of EUV generator 102 or scanner 104. The properties of these environments may induce a net charge on particles that inadvertently pass through them. The particles may include material from droplets carrying a net positive or net negative charge. Charged debris or particles may originate from sources other than droplets.

[0096] When the photomask 106 is contaminated, it is highly likely that both positively and negatively charged debris particles are present on it. These debris particles may also have different sizes, and different rigidities and elasticities. As will be explained in more detail below, the photomask cleaning system 118 utilizes the presence of both positively and negatively charged particles to effectively and efficiently remove debris particles from the photomask 106.

[0097] In some embodiments, the photomask cleaning system 118 includes a cleaning electrode 120. The cleaning electrode 120 may be in the shape of a plate having an area slightly larger than the exposure surface of the photomask 106. The photomask 106 may have an area of ​​approximately 50 cm².2 With 200cm 2 A rectangular exposure surface between [the two surfaces]. The cleaning electrode 120 may have an area of ​​80 cm². 2 With 300cm 2 The rectangular surface between. Without departing from the scope of this disclosure, the photomask 106 and the cleaning electrode 120 may have other shapes and sizes.

[0098] In some embodiments, the cleaning electrode 120 comprises a conductive material such as a metal. The cleaning electrode 120 may include one or more of iron, copper, aluminum, titanium, tungsten, platinum, gold, or other conductive metals or materials. The material of the cleaning electrode 120 may be selected to establish a strong electric field between the cleaning electrode 120 and the photomask 106, as will be described in more detail below.

[0099] When the photomask cleaning system 118 performs a cleaning process on the photomask 106, the photomask 106 and the cleaning electrode 120 are close to each other. The exposed surface of the photomask 106 faces the surface of the cleaning electrode 120. The photomask 106 may be held above the cleaning electrode 120, with the exposed surface of the photomask 106 facing down above the cleaning electrode 120. Without departing from the scope of this disclosure, the photomask 106 and the cleaning electrode 120 may be held in other relative positions during the cleaning process.

[0100] The photomask cleaning system 118 includes a voltage source 122. The voltage source 122 applies a voltage to the cleaning electrode 120. The voltage on the cleaning electrode 120 helps to establish an electric field between the cleaning electrode 120 and the photomask 106. In some cases, the voltage source 122 may also be coupled to the photomask 106 to apply a ground voltage or another voltage to the photomask 106.

[0101] The cleaning electrode 120 and the photomask 106 function as a capacitor. One plate of the capacitor is the cleaning electrode 120, and the other plate is the exposure surface of the photomask 106. The capacitance C of the capacitor is given by the following relationship:

[0102] C = A * ε / d,

[0103] Where A is the overlap area of ​​the exposure surfaces of the cleaning electrode 120 and the photomask 106, ε is the dielectric constant of the material (or vacuum) between the exposure surfaces of the cleaning electrode 120 and the photomask 106, and d is the distance between the exposure surfaces of the cleaning electrode 120 and the photomask 106. An electric field E is generated between the photomask 106 and the cleaning electrode 120 by applying a voltage between them. The electric field E is given by the following relationship:

[0104] E = V / d,

[0105] Where V is the voltage applied between the cleaning electrode 120 and the photomask 106. The total charge Q on the surface of the cleaning electrode 120 is given by the following relationship:

[0106] Q = C * V.

[0107] In some embodiments, the cleaning process is performed in a vacuum. In these cases, the dielectric constant ε associated with the capacitance C is the dielectric constant of free space. In other cases, an inert gas such as argon or molecular nitrogen may be present in the photomask cleaning system 118. These and other gases may flow through the environment of the photomask cleaning system 118 to remove debris particles.

[0108] The distance d between the cleaning electrode 120 and the photomask 106 can be between 1 cm and 10 cm. As can be seen from the electric field equation above, a smaller distance d generally results in a higher electric field. Other distances d may be used without departing from the scope of this disclosure.

[0109] During the operation of the photomask cleaning system 118, a voltage is applied between the cleaning electrode 120 and the photomask 106. This results in an electric field between the cleaning electrode 120 and the photomask 106. As previously mentioned, the debris particles on the photomask 106 are typically charged particles. Therefore, if the voltage applied to the cleaning electrode 120 is positive, the negatively charged debris particles on the exposure surface of the photomask 106 will be attracted toward the cleaning electrode 120. The magnitude of the attraction on the debris particles is equal to the magnitude of the net charge on the debris particles multiplied by the electric field E. Some of the negatively charged debris particles are removed from the surface of the photomask 106 and will move toward the surface of the cleaning electrode 120. If the voltage applied to the cleaning electrode 120 is negative, the positively charged debris particles on the exposure surface of the photomask 106 will be attracted toward the cleaning electrode 120. Some of the positively charged debris particles will be removed from the surface, and the photomask 106 will move toward the surface of the cleaning electrode 120.

[0110] The photomask cleaning system 118 periodically reverses the polarity of the voltage applied to the cleaning electrode 120. In one example, during the first part of the cleaning cycle, the voltage applied to the cleaning electrode 120 is positive. During the second part of the cleaning cycle, the voltage applied to the cleaning electrode is negative. During the first half of the cleaning cycle when the positive polarity is applied to the cleaning electrode 120, negatively charged debris particles are removed from the photomask 106 and move to the cleaning electrode 120. During the second half of the cleaning cycle when the negative polarity is applied to the cleaning electrode 120, positively charged debris particles are removed from the photomask 106 and move to the cleaning electrode 120. Changing the polarity of the voltage applied to the cleaning electrode 120 during the cleaning cycle causes positively charged and negatively charged debris particles to transfer from the photomask 106 to the cleaning electrode 120 at different parts of the cleaning cycle.

[0111] In some embodiments, the photomask cleaning system 118 includes a membrane located between the cleaning electrode 120 and the photomask 106. This membrane may be an adhesive membrane. When debris particles are drawn from the photomask 106 toward the cleaning electrode 120, the debris particles are captured by the membrane. This helps ensure that debris particles removed from the photomask 106 during one portion of the cycle are not drawn back to the photomask 106 during the next portion of the cycle. Furthermore, if debris is initially present on the cleaning electrode 120, the debris will not move from the cleaning electrode to the photomask 106 but will be captured by the membrane.

[0112] During any part of the cleaning cycle, some charged debris particles may not be removed from the photomask 106. In these cases, multiple cleaning cycles can be performed. The polarity of the voltage applied to the cleaning electrode 120 can be switched multiple times. After numerous polarity changes, even the most stubborn particles will eventually be removed from the photomask 106 and captured by the membrane.

[0113] In some cases, the membrane may need to be replaced after a certain number of polarity switches. In these cases, the cleaning electrode 120 and the membrane can be withdrawn from the photomask 106, and the membrane can be replaced. The cleaning electrode 120 and the membrane are then returned to a position close to the photomask 106, and a voltage, including one or more polarity switches, is applied again between the cleaning electrode 120 and the photomask 106. This process can be repeated multiple times until all debris particles are removed from the photomask 10 trapped by the membrane.

[0114] The photomask cleaning system 118 offers numerous advantages over other cleaning processes. The photomask cleaning system 118 can complete a thorough cleaning process in minutes. Furthermore, the photomask cleaning system 118 uses inexpensive components, including the cleaning electrode 120 and a replaceable membrane. This contrasts with other cleaning processes that require several days to complete and use expensive tools and procedures, such as UV irradiation, flowing ozone, performing sonic cleaning procedures, rinsing with deionized water, and rotary drying.

[0115] To reduce the possibility of contaminating the exposure surface of photomask 106 when it is not in use, EUV system 100 includes EUV memory 114. EUV memory 114 may include a storage and protection chamber that surrounds and protects photomask 106 when it is not in use. Photomask 106 can be immediately enclosed in EUV memory 114 after initial fabrication. Photomask 106 remains in EUV memory 114 during transport from the manufacturing site to the wafer processing site. EUV memory 114 provides very strong protection against contamination when photomask 106 is not in use. However, EUV memory 114 does not protect photomask 106 when it is loaded into scanner 104.

[0116] The photomask 106 remains in the EUV memory 114 until it is used in the EUV lithography process. At this point, the photomask 106 is transferred from the EUV memory 114 to the scanner 104. The EUV memory 114, or a portion thereof, may be carried in the scanner 104. The photomask 106 is then unloaded from the EUV memory to a chuck (not shown) in the scanner 104. The chuck holds the photomask 106 during the EUV process. After the EUV process, the photomask 106 is unloaded from the chuck to the EUV memory 114.

[0117] When photomask 106 is loaded onto scanner 104 for lithography, it may become contaminated. One source of contaminants is debris and particles from EUV generator 102. Specifically, when droplets are irradiated within EUV generator 102, material may be ejected from the droplets. The material ejected from the droplets includes droplet particles. Some droplet particles may enter scanner 104 and eventually fall onto the exposure surface of photomask 106. Debris or particles from sources other than droplets may also enter scanner 104 and eventually fall onto the exposure surface of photomask 106.

[0118] EUV system 100 may include a photomask analyzer 117. The photomask analyzer 117 can analyze photomask 106 to detect the presence of any contaminants. The photomask analyzer 117 can detect debris or particles on the exposed surface of photomask 106 or at other locations on photomask 106. The photomask analyzer 117 can be used at any time when the photomask is loaded into scanner 104 or unloaded from scanner 104. In other words, the photomask analyzer 117 can analyze the contamination of photomask 106 at any time when photomask 106 is unloaded from photomask memory 114 or about to be loaded into photomask memory 114.

[0119] The photomask analyzer 117 may include various types of scanning systems for scanning the exposed surface or other surfaces of the photomask 106. The scanning system may include one or more image capture devices that capture images of the photomask 106. The images may then be transmitted to an image analysis system, which analyzes the images to detect the presence of debris or contaminants. The scanning system may include other types of optical debris detection systems. Various other types of scanning systems may be used in the photomask analyzer 117 without departing from the scope of this disclosure. In response to the photomask analyzer 117 detecting debris on the photomask 106, the photomask 106 may be taken to the photomask cleaning system 118.

[0120] EUV system 100 includes one or more robotic arms 112. The one or more robotic arms 112 can transfer photomasks 106 between scanner 104, EUV memory 114, photomask analyzer 117, and photomask cleaning system 118. Without departing from the scope of this disclosure, EUV system 100 may include other types of photomask transfer systems.

[0121] Figure 2A A side view of a photomask cleaning system 118 according to some embodiments. Figure 2A Photomask cleaning system 118 is Figure 1 An example of a photomask cleaning system 118. The photomask cleaning system 118 can be used to clean debris from the photomask 106 of an EUV lithography system.

[0122] The photomask cleaning system 118 includes a cleaning electrode 120. The cleaning electrode 120 includes a flat top surface 128. Therefore, the cleaning electrode 120 has a plate shape. The cleaning electrode 120 may include other shapes without departing from the scope of this disclosure.

[0123] The cleaning electrode 120 may include a conductive material, enabling it to generate an electric field between the cleaning electrode 120 and the photomask 106. The cleaning electrode 120 may be a metal, including one or more of aluminum, copper, iron, gold, titanium, platinum, or other metals. The cleaning electrode 120 may include alloys of various metals or other materials. Without departing from the scope of this disclosure, the cleaning electrode 120 may include other materials.

[0124] The photomask cleaning system 118 includes one or more support pins 124. The support pins 124 are located on the top surface 128 of the cleaning electrode 120. The support pins 124 may protrude from the top surface 128 of the cleaning electrode 120 to a height between 2 mm and 10 mm. The top surface 128 of the cleaning electrode 120 may include recesses or slots sized to receive and retain the support pins 124. The support pins 124 may be made of ceramic, plastic, or conductive material. Ceramic pins may have other materials and dimensions without departing from the scope of this disclosure.

[0125] The photomask cleaning system 118 includes a membrane 126. The membrane 126 rests on top of a support pin 124. The support pin 124 maintains a gap between the membrane 126 and the top surface 128 of the cleaning electrode 120. For reasons explained in more detail below, the membrane 126 may be referred to as a debris trapping membrane.

[0126] The film 126 may include an adhesive surface. Charged debris particles traveling from the photomask 106 toward the cleaning electrode 120 fall onto the film 126. Because the film 126 has an adhesive surface, the charged debris particles adhere to the adhesive film 126. The adhesive film 126 may adhere to both a top surface and a bottom surface, such that debris particles moving from the top surface 128 of the cleaning electrode 120 toward the photomask 106 will adhere to the adhesive bottom surface of the film 126.

[0127] Membrane 126 may include a flexible polymer membrane capable of quickly attaching to and quickly removing from support pin 124. Without departing from the scope of this disclosure, membrane 126 may include other flexible materials.

[0128] Membrane 126 may be a rigid member. Membrane 126 may include a thin sheet of ceramic or polymer material. The rigid member can be easily placed on and removed from support pin 124. Without departing from the scope of this disclosure, membrane 126 may include other types of rigid members and other materials.

[0129] Voltage source 122 can be coupled to cleaning electrode 120 via an electrical connector. The electrical connector may include wires, rods or other types of electrical connectors that facilitate the application of voltage from voltage source 122 to cleaning electrode 120.

[0130] Figure 2B According to some embodiments Figure 2A A top view of the cleaning electrode 120. The cleaning electrode 120 is rectangular. The cleaning electrode 120 may also be square. The cleaning electrode 120 has a first dimension D1 and a second dimension D2. D1 and D2 may be equal or unequal. The values ​​of D1 and D2 may be between 9 cm and 17 cm. Without departing from the scope of this disclosure, the cleaning electrode 120 may have other shapes and sizes.

[0131] Figure 2B The top view also shows the support pins 124. Each support pin 124 is located near a corner of the top surface 128 of the cleaning electrode 120. However, different numbers, shapes and positions of support pins may be present without departing from the scope of this disclosure.

[0132] Figure 2B Membrane 126 is not shown. When membrane 126 is positioned on support pin 124, membrane 126 covers top surface 128. Membrane 126 may be rectangular. The dimensions of membrane 126 may be slightly smaller or slightly larger than D1 and D2. Alternatively, membrane 126 may have the same dimensions as cleaning electrode 120. Membrane 126 may have other shapes and dimensions without departing from the scope of this disclosure.

[0133] Figure 3AThis is an illustration of a chuck 130 holding a photomask 106 above a cleaning electrode 120 of a photomask cleaning system 118, according to some embodiments. The photomask cleaning system 118 can be substantially similar to... Figure 2A and Figure 2B A photomask cleaning system 118. A chuck 130 holds a photomask 106, with the exposure surface 132 of the photomask 106 facing downwards. The exposure surface 132 includes a pattern for patterning the wafer, such as regarding... Figure 1 As stated above.

[0134] Figure 3A Debris particles 142, 144, 146, 148, 150, and 152 are shown. Debris particles 142, 148, and 150 carry a net negative charge. Debris particles 144, 146, and 152 carry a net positive charge. For illustrative purposes, Figure 3A The debris particles appear to be much larger relative to photomask 106 than in practice. In practice, the debris particles may have a diameter or size between 10 nm and 200 μm, but may have other sizes without departing from the scope of this disclosure.

[0135] The exposure surface 132 of the photomask 106 is spaced apart from the top surface 128 of the cleaning electrode 120 by a distance d. The distance d can be between 1 cm and 10 cm. Other distances may be used without departing from the scope of this disclosure.

[0136] The film 126 rests on the support pin 124. The film 126 is located between the exposure surface 132 of the photomask 106 and the top surface 128 of the cleaning electrode 120. As previously mentioned, the film 126 may be an adhesive film or may have an adhesive surface.

[0137] exist Figure 3A In the diagram, voltage source 122 does not supply voltage to cleaning electrode 120. (Regarding...) Figures 3B to 3D Describes the application of voltage.

[0138] exist Figure 3BIn this process, voltage source 122 applies a positive voltage to cleaning electrode 120. Voltage source 122 can also ground photomask 106. As a result, an electric field is generated between cleaning electrode 120 and photomask 106. Positive charge accumulates on the top surface 128 of cleaning electrode 120. Negatively charged debris particles 142, 148, and 150 are attracted to cleaning electrode 120 by an electric current. This force is sufficient to remove negatively charged particles 148 and 150. Negatively charged particles 148 and 150 are accelerated toward cleaning electrode 120. Negatively charged particles 148 and 150 encounter membrane 126. Negatively charged particles 148 and 150 now adhere to membrane 126. However, negatively charged particle 142 adheres more tightly to photomask 106. Therefore, negatively charged particles 142 will not be removed from the exposure surface 132 of the photomask 106. Positively charged particles 144, 146, and 152 are removed from the cleaning electrode 120 and remain at the exposure surface 132 of the photomask 106.

[0139] exist Figure 3C In this process, voltage source 122 applies a negative voltage to cleaning electrode 120. Voltage source 122 can also ground photomask 106. As a result, an electric field is generated between cleaning electrode 120 and photomask 106. Negative charge accumulates on the top surface 128 of cleaning electrode 120. Positively charged debris particles 144, 146, and 152 are attracted to cleaning electrode 120 by an electric force. This force is sufficient to remove positively charged debris particles 144 and 152. Positively charged debris particles 144 and 152 are accelerated toward cleaning electrode 120. Positively charged debris particles 144 and 152 encounter membrane 126. Positively charged debris particles 144 and 152 now adhere to membrane 126. However, positively charged particle 146 adheres more tightly to photomask 106. Therefore, the positively charged particles 146 will not be removed from the exposure surface 132 of the photomask 106.

[0140] exist Figure 3D In the middle, the film 126 has been replaced. This can be achieved by quickly peeling off the film 126 and replacing it with a new film 126 by removing the cleaning electrode 120 from near the photomask 106. Figure 3D As can be seen, debris particles 144, 148, 150 and 152 are absent because they were carried away with the previous membrane 126.

[0141] exist Figure 3D In the process, voltage source 122 applies a positive voltage to cleaning electrode 120. Negatively charged debris particles 142 are attracted from the exposure surface 132 of photomask 106 to cleaning electrode 120. Negatively charged debris particles 142 adhere to film 126.

[0142] exist Figure 3EIn this process, voltage source 122 applies a negative voltage to cleaning electrode 120, causing positively charged debris particles 146 to be attracted from the exposure surface 132 of photomask 106 to cleaning electrode 120, and adhering to the film 126. At this stage, all debris particles have been removed from the exposure surface 132 of photomask 106. In fact, regarding... Figures 3A to 3E The cleaning process shown may include more cycles of switching the polarity of the voltage applied to the cleaning electrode 120. In practice, the cleaning process may include more instances of replacing membrane 126 with a cleaning membrane.

[0143] Figures 4A to 4C Multiple voltage waveforms 402, 404, and 406 according to some embodiments are shown. These voltage waveforms can be applied to the cleaning electrode 120 by a voltage source 122. At time t0, each of voltage waveforms 402, 404, and 406 applies a positive voltage amplitude Vp. At time t1, each of voltage waveforms 402, 404, and 406 crosses 0V and switches its polarity from positive to negative. This corresponds to switching the polarity of the voltage applied to the cleaning electrode 120. At time t2, one cycle of voltage waveforms 402, 404, and 406 has ended. At time t2, each of voltage waveforms 402, 404, and 406 has reached a negative voltage amplitude Vn. Each of voltage waveforms 402, 404, and 406 can be repeated multiple times during the cleaning process. Although each of voltage waveforms 402, 404 and 406 is shown to begin with a positive voltage polarity, each of voltage waveforms 402, 404 and 406 may alternatively begin with a negative voltage polarity and then switch to a positive voltage polarity.

[0144] Voltage waveform 402 corresponds to a square wave voltage waveform. The applied voltage starts at Vp and continues at Vp until time t1 when the voltage polarity switches to Vn. The voltage remains at Vn until time t2. At time t2, the period can repeat and the voltage can switch polarity back to Vp.

[0145] The voltage Vp can have a range between 5V and 100V. The voltage Vn can have a range between -5V and -100V. Other voltages may be used without departing from the scope of this disclosure.

[0146] A single cycle can have a duration between ten seconds and one minute. The number of cycles used in a cleaning process can range from one cycle to 50 cycles. Other durations and numbers of cycles may be used without departing from the scope of this disclosure.

[0147] Voltage waveform 404 corresponds to a sinusoidal voltage waveform. The applied voltage starts at Vp and decreases sinusoidally towards Vn. Waveform 404 crosses 0V at time t1. Waveform 404 reaches Vn at time t2. At this point, waveform 404 can repeat and transition quickly back to Vp. Alternatively, waveform 404 can increase sinusoidally back to Vp.

[0148] Voltage waveform 406 corresponds to a linear voltage waveform. The applied voltage starts at Vp and decreases at a linear rate to Vn. Waveform 404 crosses 0V at time t1. Waveform 404 reaches Vn at time t2. At this point, waveform 404 can repeat and transition quickly back to Vp. Alternatively, waveform 406 can increase linearly back to Vp.

[0149] Voltage waveforms 402, 404, and 406 illustrate voltage waveforms that can be applied by voltage source 122. However, in reality, the voltage appearing at the top surface 128 of the cleaning electrode 120 will follow a slightly different form than voltage waveforms 402, 404, and 406. This is because the voltage on the capacitor plates cannot change instantly. Instead, the voltage on the capacitor plates changes as charge accumulates or dissipates. Charge cannot accumulate or dissipate instantly. Therefore, the actual voltage at the top surface 128 will not exactly correspond to the voltage output by voltage source 122.

[0150] Figure 4D A graph 408 illustrates the charge Q at the top surface 128 of the cleaning electrode 120 according to some embodiments. Graph 408 may correspond to the charge Q accumulated when the voltage source 122 attempts to output a square wave. At time t0, there is no initial charge accumulation at the top surface 128. The voltage source outputs a positive voltage Vp. Charge rapidly begins to accumulate at the top surface 128. Shortly after time t0, the accumulated charge exceeds 50% of the total possible charge that can accumulate for a positive voltage Vp. The accumulated charge continues to approach 100% until time t1. At time t1, the voltage source 122 switches the polarity of the voltage from positive to negative and begins to output a negative voltage polarity Vn. The accumulated positive charge begins to decrease and crosses 0% shortly after time t1. Negative charge accumulates on surface 128, exceeding 50% of the total possible negative charge accumulation, and continues to approach 100% of the total negative charge accumulation until time t2. At time t2, voltage source 122 again switches the polarity of its negative voltage Vn to positive voltage Vp. The accumulated charge begins to change from -100% to +100%. Charge accumulation may differ from this without departing from the scope of this disclosure. The voltage at the top surface 128 of the cleaning electrode 120 has the same form as the charge accumulation.

[0151] During the cycle, various types of energy may be present in the system. These may include thermal energy associated with debris, mechanical or kinetic energy associated with debris, energy associated with elastic or plastic deformation of debris, or other types of energy that can affect the debris removal process. For example, at the beginning of the waveform cycle, the application of voltage may cause electrothermal heating of the debris particles on the exposure surface 132 of the photomask 106. Before the polarity switch, in instances where the debris particles and the cleaning electrode initially have the same polarity, as the debris particles are repelled by the cleaning electrode 120, the debris particles will possess mechanical or kinetic energy and may move laterally along the exposure surface 132 of the photomask 106. Depending on the material of the debris particles, the debris particles may undergo plastic or elastic deformation based on electrostatic forces. After the polarity switch, as the debris particles are attracted to the cleaning electrode 120 by electrostatic forces, the debris particles acquire mechanical energy.

[0152] Figure 5 The accompanying drawings show a photomask 106 according to some embodiments. The photomask 106 is based on... Figure 1 and Figures 3A to 3E An example of a photomask. Photomask 106 includes a substrate 160, a reflective multilayer 164 on the substrate 160, a buffer layer 165 on the reflective multilayer 164, and an absorber layer 166 on the buffer layer 165. The substrate 160 includes a back surface 162. The back surface 162 can be considered as the surface of photomask 106 opposite to the exposure surface 132. The fabrication process of photomask 106 ultimately results in photomask 106 having a selected pattern in the absorber layer 166. Figure 5 In this example, the pattern is indicated by the grooves 172 in the absorption layer 166. The exposure surface 132 may correspond to the exposure surface of the absorption layer 166, the exposure surface of the buffer layer 165, or a combination of the top surface of the exposure surface of the absorption layer 166 and the exposure surface of the buffer layer 165. Without departing from the scope of this disclosure, the photomask 106 may include other structures and arrangements.

[0153] The substrate 160 includes a low thermal expansion material. The low thermal expansion material substrate 160 is used to minimize image distortion caused by heating of the photomask 106. The low thermal expansion material substrate 160 may include a material with low defect levels and a smooth surface.

[0154] In some embodiments, substrate 160 may include SiO2. Substrate 160 may be doped with titanium dioxide. Without departing from the scope of this disclosure, substrate 160 may include other low thermal expansion materials besides those described above.

[0155] Although not shown herein, in some embodiments, substrate 160 may be located on a conductive layer. The conductive layer helps to electrostatically hold photomask 106 during manufacture and use. In some embodiments, the conductive layer comprises chromium nitride. Other materials may be included in the conductive layer without departing from the scope of this disclosure.

[0156] Photomask 106 includes a reflective multilayer 164. The reflective multilayer 164 is located on substrate 160. The reflective multilayer 164 is used to reflect extreme ultraviolet light during lithography processes using photomask 106. The reflective characteristics of the reflective multilayer 164 are described in more detail below.

[0157] In some embodiments, the reflective multilayer 164 operates based on the reflective properties of the interface between the two materials. Specifically, when light is incident on the interface between two materials with different refractive indices, reflection occurs. When the refractive index difference is large, most of the light is reflected.

[0158] The reflective multilayer 164 comprises multiple pairs of layers. Each pair of layers includes a first material layer and a second material layer. The materials and thicknesses of the layers are selected to promote reflection and constructive interference of extreme ultraviolet (EUV) light. In some embodiments, each pair of layers includes a molybdenum layer and a silicon layer. In one example, the thickness of the molybdenum layer is between 2 nm and 4 nm. In one example, the thickness of the silicon layer is between 3 nm and 5 nm. The thickness of the layers in the reflective multilayer 164 is selected based on the expected wavelength of the EUV light used in the lithography process and the expected incident angle of the EUV light during the lithography process. According to some embodiments, the number of layer pairs is between 20 and 60 pairs. Other materials, thicknesses, number of pairs, and layer configurations in the reflective multilayer 164 may be used without departing from the scope of this disclosure. Other wavelengths of EUV light may be used without departing from the scope of this disclosure.

[0159] In some embodiments, a buffer layer 165 is located on the reflective multilayer 164. One purpose of the buffer layer 165 is to protect the reflective multilayer during the etching process of the absorber layer 166. Therefore, the buffer layer 165 comprises a material that resists etching during the etching process of the absorber layer 166. The etching process and the material of the absorber layer will be described in more detail below.

[0160] In some embodiments, buffer layer 165 includes ruthenium. Buffer layer 165 may include ruthenium compounds, including ruthenium boride and ruthenium silicide. Buffer layer may include chromium, chromium oxide, or chromium nitride. Buffer layer 165 may be deposited using a low-temperature deposition process to prevent buffer layer 165 from diffusing into reflective multilayer 164. In some embodiments, buffer layer 165 has a thickness between 2 nm and 4 nm. Other materials, deposition processes, and thicknesses may be used for buffer layer 165 without departing from the scope of this disclosure.

[0161] Absorption layer 166 is located on buffer layer 165. The material of absorption layer 166 is chosen to have a high absorption coefficient for the wavelength of extreme ultraviolet light that will be used in the photomask 106 in the lithography process. In other words, the material of absorption layer 166 is chosen to absorb extreme ultraviolet light.

[0162] In some embodiments, the thickness of the absorber layer 166 is between 40 nm and 100 nm. In some embodiments, the absorber layer 166 comprises a material selected from the group consisting of chromium, chromium oxide, titanium nitride, tantalum nitride, tantalum, titanium, aluminum-copper, palladium, boron tantalum nitride, boron tantalum oxide, aluminum oxide, molybdenum, or other suitable materials. Other materials and thicknesses may be used for the absorber layer 166 without departing from the scope of this disclosure.

[0163] In some embodiments, the absorbent layer 166 includes a first absorbent layer 168 and a second absorbent layer 170. The first absorbent layer 166 is located on the buffer layer 165. The second absorbent layer 170 is located on the first absorbent layer 168.

[0164] In some embodiments, the first absorber layer 168 comprises boron tantalum nitride. The second absorber layer 170 comprises boron tantalum oxide. The thickness of the first absorber layer is between 30 nm and 80 nm. The thickness of the second absorber layer 170 is between 1 nm and 40 nm. Without departing from the scope of this disclosure, the absorber layer 166 may comprise materials, thicknesses, and number of layers different from those described above. In some embodiments, the absorber layer 166 comprises only a single absorber layer. Therefore, the absorber layer 166 may be an absorber layer.

[0165] Figure 5 The layers of the photomask 106 shown can be formed by various thin film deposition processes. Thin film deposition processes can include physical vapor deposition processes, such as evaporation and DC magnetron sputtering; electroplating processes, such as electroless plating or electroplating; chemical vapor deposition processes, such as atmospheric pressure chemical vapor deposition, low pressure chemical vapor deposition, plasma-enhanced chemical vapor deposition, high-density plasma chemical vapor deposition, ion beam deposition, spin coating, organometallic decomposition, and / or other methods known in the art.

[0166] Figure 5 Also shown are negatively charged debris particles 174 and positively charged debris particles 176. The charged debris particles 174 and 176 can be wholly or partially embedded in the trench 172. This can be achieved using the foregoing description... Figures 1 to 4D The described principle removes debris particles.

[0167] Figure 6 Image of photomask 106 according to some embodiments. Figure 6 The view is of the exposure surface 132 of the photomask 106 looking downwards. Figure 6The image also shows debris 178 accumulated on the exposure surface 132 of the photomask 106. The photomask 106 may have other shapes, patterns and configurations without departing from the scope of this disclosure.

[0168] Figure 7 This is a perspective view of a photomask 106 according to some embodiments. Figure 7 In this example, the exposure surface 132 faces upwards. Figure 7 The X, Y, and Z axes are shown. The photomask 106 includes a pattern 180. In Figure 5 In this example, pattern 180 is in the shape of the letter F. In reality, pattern 180 will not be in the shape of any letter. The photomask 106 includes notches 181 at three corners. The photomask 106 includes a barcode 183 for identification purposes. The photomask 106 includes a target 182 for alignment purposes. Without departing from the scope of this disclosure, the photomask 106 may include other shapes, patterns, and configurations.

[0169] Figure 8 This is a flowchart of a method 800 for cleaning a photomask according to some embodiments. Method 800 can utilize the foregoing description... Figures 1 to 7 The system, components, and processes are described. In step 802, method 800 includes the following step: positioning a cleaning electrode near the exposure surface of a photomask. An example of a cleaning electrode is... Figure 1 The cleaning electrode 120. An example of the exposure surface is... Figure 3A The exposure area is 132. An example of a photomask is... Figure 1 Photomask 106. In step 804, method 800 includes the step of applying a voltage having a first polarity to the cleaning electrode. In step 806, method 800 includes the step of switching the voltage from the first polarity to a second polarity opposite to the first polarity.

[0170] Figure 9 This is a flowchart of a method 900 for cleaning a photolithography mask according to some embodiments. In step 902, method 900 includes the following step: performing an extreme ultraviolet (EUV) lithography process using an EUV photomask. An example of a photomask is... Figure 1 The photomask 106. In step 904, method 900 includes the following step: after performing an extreme ultraviolet (EUV) lithography process, positioning a cleaning electrode near the exposure surface of the EUV photomask. An example of a cleaning electrode is... Figure 1 The cleaning electrode 120. An example of the exposure surface is... Figure 3A The exposure surface 132. In step 906, method 900 includes the following steps: cleaning debris from the exposure surface by using a cleaning electrode to generate an electric field of alternating polarities.

[0171] In some embodiments, a method for cleaning an extreme ultraviolet (EUV) mask includes the steps of: positioning a cleaning electrode adjacent to the exposure surface of a photomask; applying a voltage of a first polarity to the cleaning electrode; and switching the voltage from the first polarity to a second polarity opposite to the first polarity. In some embodiments, the method further includes the step of: positioning a first film between the cleaning electrode and the exposure surface when the voltage is applied. In some embodiments, the method further includes the step of: attracting a plurality of charged debris particles of the second polarity from the exposure surface to the first film when the voltage is at the first polarity. In some embodiments, the method further includes the step of: attracting a plurality of charged debris particles of the first polarity from the exposure surface to the first film when the voltage is at the second polarity. In some embodiments, the method further includes the steps of: removing the first film between the cleaning electrode and the exposure surface; positioning a second film between the cleaning electrode and the exposure surface; applying the voltage having the first polarity to the cleaning electrode after positioning the second film between the cleaning electrode and the exposure surface; and switching the voltage from the first polarity to the second polarity after positioning the second film between the cleaning electrode and the exposure surface. In some embodiments, the step of positioning the first film between the cleaning electrode and the exposure surface includes the step of: coupling the first film to a plurality of support pins located on the cleaning electrode. In some embodiments, the first film comprises a polymer material.

[0172] In some embodiments, a method for cleaning an extreme ultraviolet (EUV) mask includes the steps of: performing an UV lithography process using an UV photomask; positioning a cleaning electrode adjacent to the exposure surface of the UV photomask after performing the UV lithography process; and cleaning debris from the exposure surface by generating an alternating electric field using the cleaning electrode. In some embodiments, the method further includes the steps of: capturing a first portion of the debris using a first film located between the cleaning electrode and the exposure surface when the electric field is generated. In some embodiments, the method further includes the steps of: replacing the first film with a second film; and capturing a second portion of the debris using the second film when the electric field is generated using the cleaning electrode. In some embodiments, the method further includes the step of: generating the electric field by applying an alternating voltage to the cleaning electrode. In some embodiments, the debris includes a plurality of particles derived from a plurality of droplets used to generate extreme ultraviolet light during the UV lithography process. In some embodiments, positioning the cleaning electrode near the exposure surface includes the step of: positioning the cleaning electrode directly below the exposure surface. In some embodiments, generating the electric field includes the step of: applying a ground voltage to the UV photomask.

[0173] In some embodiments, a system for cleaning an extreme ultraviolet (EUV) mask includes a cleaning electrode and a debris-trapping membrane supported near and spaced apart from the cleaning electrode. The system includes a voltage source configured to attract debris from the photolithography mask to the debris-trapping membrane by applying alternating voltages to the cleaning electrode when the cleaning electrode is adjacent to the photolithography mask, wherein the debris-trapping membrane is located between the photolithography mask and the cleaning electrode. In some embodiments, the system further includes a plurality of support pins extending from a surface of the cleaning electrode, wherein the support pins support the debris-trapping membrane adjacent to and spaced apart from the cleaning electrode. In some embodiments, the debris-trapping membrane is a flexible membrane. In some embodiments, the debris-trapping membrane is a rigid membrane. In some embodiments, the cleaning electrode has a flat surface facing the debris-trapping membrane. In some embodiments, the photolithography mask is an extreme ultraviolet (EUV) mask.

[0174] The foregoing outlines features of several embodiments to enable those skilled in the art to better understand the various aspects of this disclosure. Those skilled in the art should understand that this disclosure can be readily used as a basis for designing or modifying other processes and structures to achieve the same objectives and / or advantages as the embodiments described herein. Those skilled in the art should also recognize that these equivalent constructions do not depart from the spirit and scope of this disclosure, and that various changes, substitutions, and modifications can be made to these equivalent constructions without departing from the spirit and scope of this disclosure.

Claims

1. A method for cleaning an extreme ultraviolet (EUV) shield, characterized in that, Includes the following steps: Position a cleaning electrode near an exposure surface of a photomask; A first film is coupled to a plurality of support pins located on the cleaning electrode, and the first film is positioned between the cleaning electrode and the exposure surface, and the plurality of support pins maintain a gap between the first film and the top surface of the cleaning electrode, and the bottom surface and the top surface of the first film have adhesive surfaces. A voltage of a first polarity is applied to the cleaning electrode. When the voltage is at the first polarity, a plurality of charged debris particles of a second polarity opposite to the first polarity are attracted from the exposed surface to the top surface of the first film, and the plurality of charged debris particles are attracted from the top surface of the cleaning electrode to the bottom surface of the first film through the gap; and The voltage is switched from the first polarity to the second polarity, which is opposite to the first polarity.

2. The method according to claim 1, characterized in that, The step of positioning the first film between the cleaning electrode and the exposure surface includes the step of positioning the cleaning electrode directly below the exposure surface.

3. The method according to claim 1, characterized in that, The process further includes the following step: applying a ground voltage to the photomask.

4. The method according to claim 2, characterized in that, The method further includes the following steps: when the voltage is at the second polarity, a plurality of charged debris particles of the first polarity are attracted from the exposure surface to the first film.

5. The method according to claim 2, characterized in that, Further steps include: Remove the first film between the cleaning electrode and the exposed surface; A second film is positioned between the cleaning electrode and the exposure surface; After positioning the second film between the cleaning electrode and the exposure surface, the voltage having the first polarity is applied to the cleaning electrode; and After positioning the second film between the cleaning electrode and the exposure surface, the voltage is switched from the first polarity to the second polarity.

6. The method according to claim 2, characterized in that, The multiple support pins extend from one surface of the cleaning electrode.

7. The method according to claim 2, characterized in that, The first membrane comprises a polymer material.

8. A method for cleaning an extreme ultraviolet (EUV) shield, characterized in that, Includes the following steps: Using a single-electro-ultraviolet photomask for single-electro-ultraviolet lithography; After performing the extreme ultraviolet lithography process, a cleaning electrode is positioned near an exposure surface of the extreme ultraviolet photomask. A first film is coupled to a plurality of support pins located on the cleaning electrode, and the first film is positioned between the cleaning electrode and the exposure surface, and the plurality of support pins maintain a gap between the first film and the top surface of the cleaning electrode, and the bottom surface and the top surface of the first film are adhesive. and The cleaning electrode and the exposed surface are cleaned by generating an electric field with alternating polarities using the cleaning electrode.

9. The method according to claim 8, characterized in that, Further steps include: When the electric field is generated, a first portion of the debris is captured using the first film located between the cleaning electrode and the exposure surface.

10. The method according to claim 9, characterized in that, Further steps include: Replace the first membrane with a second membrane; and When the cleaning electrode is used to generate the electric field, a second portion of the debris is captured using the second membrane.

11. The method according to claim 8, characterized in that, Further steps include: The electric field is generated by applying an alternating voltage to the cleaning electrode.

12. The method according to claim 8, characterized in that, The debris comprises multiple particles derived from multiple droplets used to generate extreme ultraviolet light during the extreme ultraviolet lithography process.

13. The method according to claim 8, characterized in that, The step of positioning the cleaning electrode near the exposure surface includes the following steps: positioning the cleaning electrode directly below the exposure surface.

14. The method according to claim 8, characterized in that, The steps to generate this electric field include applying a grounding voltage to the ultraviolet photomask.

15. A system for cleaning extreme ultraviolet (EUV) shields, characterized in that, Include: One clean electrode; Multiple support pins are located on the cleaning electrode; A debris-catching membrane is coupled to the plurality of support pins located on the cleaning electrode and spaced apart from the top surface of the cleaning electrode, wherein the bottom surface of the debris-catching membrane and the top surface of the debris-catching membrane are adhesive. and A voltage source is provided to apply an alternating voltage to the cleaning electrode when the cleaning electrode is adjacent to a photomask to attract debris from the photomask to the debris trapping membrane, wherein the debris trapping membrane is located between the photomask and the cleaning electrode, and the plurality of support pins maintain a gap between the debris trapping membrane and the top surface of the cleaning electrode.

16. The system according to claim 15, characterized in that, The plurality of support pins extend from one surface of the cleaning electrode, wherein the plurality of support pins support the debris trapping membrane which is adjacent to and spaced apart from the cleaning electrode.

17. The system according to claim 15, characterized in that, The debris-capturing membrane is a flexible membrane.

18. The system according to claim 15, characterized in that, The debris-capturing membrane is a rigid membrane.

19. The system according to claim 15, characterized in that, The cleaning electrode has a flat surface facing the debris-capturing membrane.

20. The system according to claim 15, characterized in that, The photomask is an ultraviolet photomask.

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