TWI826575B - Pellicle, patterning device assembly, and dynamic gas lock assembly for euv lithography - Google Patents

Abstract

A pellicle for EUV lithography comprising: a frame; and a membrane supported by the frame, wherein the membrane comprises: a metallic or semimetallic layer, wherein the membrane comprises pores at a density of at least 5 per μm². The membrane may have a substrate layer for supporting the metallic or semimetallic layer, the substrate layer comprising for example silicon obtained from silicon on insulator or polysilicon.

Description

Protective film, patterning device assembly and dynamic air lock assembly for extreme ultraviolet (EUV) lithography

The invention relates to a protective film, a diaphragm, a patterning device assembly and a dynamic air lock assembly for extreme ultraviolet (EUV) lithography.

A lithography apparatus is a machine that applies a desired pattern to a substrate, usually to a target portion of the substrate. Lithography equipment may be used, for example, in integrated circuit (IC) manufacturing. In that case, a patterning device (which is alternatively called a reticle or a reticle) can be used to create circuit patterns to be formed on individual layers of the IC. This pattern can be transferred to a target portion (eg, the portion containing the dies, a die or dies) on a substrate (eg, a silicon wafer). Transfer of the pattern is typically performed by imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. Typically, a single substrate will contain a network of sequentially patterned adjacent target portions.

Lithography is widely recognized as one of the critical steps in the fabrication of ICs and other devices and/or structures. However, as the dimensions of features fabricated using lithography become smaller and smaller, lithography is becoming a more decisive factor in enabling the fabrication of small ICs or other devices and/or structures.

The theoretical estimate of the pattern printing limit can be given by the Rayleigh resolution criterion, as shown in equation (1):

where λ is the wavelength of the radiation used, NA is the numerical aperture of the projection system used to print the pattern, k1 is the process-dependent adjustment factor (which is also called the Rayleigh constant), and CD is the feature size of the printed feature (or critical size). From equation (1) it can be seen that a reduction in the minimum printable size of a feature can be obtained in three ways: by shortening the exposure wavelength λ, by increasing the numerical aperture NA, or by reducing the value of k1.

In order to shorten the exposure wavelength and therefore the minimum printable size, the use of extreme ultraviolet (EUV) radiation sources has been proposed. EUV radiation is electromagnetic radiation having a wavelength in the range of 10 to 20 nm (eg, in the range of 13 to 14 nm). It has further been proposed that EUV radiation with wavelengths less than 10 nm (eg, in the range of 5 to 10 nm, such as 6.7 nm or 6.8 nm) may be used. This radiation is called extreme ultraviolet radiation or soft x-ray radiation. Possible sources include, for example, laser-generated plasma sources, discharge plasma sources, or sources based on synchrotron radiation provided by an electron storage ring.

Lithography equipment includes a patterning device (eg, a reticle or a reticle). Radiation is provided through or reflected from the patterning device to form an image on the substrate. Diaphragm assemblies are available to protect patterned devices from airborne particles and other forms of contamination. The diaphragm assembly used to protect the patterning device can be called a protective film. Contamination on the surface of the patterned device can cause manufacturing defects on the substrate. The diaphragm assembly may include a frame and a diaphragm stretched across the frame.

In use, the performance of the membrane may degrade over time, especially at higher temperatures. At higher temperatures, the membrane releases a gas. It is desirable to keep the temperature of the pellicle relatively low. It is also desirable that the pellicle transmits a high proportion of EUV radiation and has a low speckle on the substrate.

According to an aspect of the present invention, a protective film for EUV lithography is provided, which includes: a frame; and a diaphragm supported by the frame, wherein the diaphragm includes: a metal or semi-metal layer, wherein the The membrane contains pores with a density of at least 5/ ^μm2 .

According to an aspect of the present invention, a membrane for a protective film in EUV lithography is provided, which includes: a non-gold metal or semi-metal layer, wherein the membrane includes a pore with a density of at least 5/μm ² .

According to an aspect of the present invention, a method of manufacturing a pellicle for EUV lithography is provided, which includes: coating a first material on a second material to form a frame of the pellicle; Covering a third material for forming a metal or semi-metal layer of the protective film on a substrate layer of the membrane; and forming pores in the substrate layer at a density of at least ⁵ /μm2.

According to an aspect of the present invention, a membrane for a pellicle used in EUV lithography is provided, which includes a grating that includes a plurality of holes, apertures or protrusions. The plurality of holes may include, for example, circles, squares, circular squares or holes of any shape. The membrane may, for example, comprise a main film or layer. The thickness of the main film or layer in the grating may range, for example, from 20 nm to 100 nm. In one embodiment, the main film or layer may also be referred to as a core or separator core. Preferably, the grating spacing is less than 200nm to ensure good emissivity. The grating pitch can be defined as the distance between the centers of adjacent holes in the grating. In one embodiment, the main grating pitch is preferably less than 100 nm to ensure a low spot at the wafer level. A smaller grating pitch, such as 30nm or less, prevents debris particles from landing on the reticle. The membrane of a pellicle for EUV lithography according to any embodiment may comprise a metal layer with a thickness between 4 and 15 nm, or a semi-metal with a thickness in the range of 20 to 80 nm. If the membrane is more open, the metal layer is preferably thicker. In one embodiment, the diaphragm grating has substantially square openings (ie, apertures) spaced 30 to 200 nm apart, such as 100 nm, and a percentage of the opening area or defined by the grating openings The opening is 50% to 90%, such as 75% opening or opening area. A radiating Ru layer with a thickness of approximately 8 nm has an emissivity >0.35. The material of the pellicle membrane may include, for example, an SOI Si membrane core combined with a metal layer. In another embodiment, the diaphragm grating comprising SOI Si has substantially circular or square openings covering 50% to 90% of the diaphragm area, a grating pitch of less than 100 nm, and a metal layer having a thickness in the range of 5 to 15 nm , this metal layer provides low spot and emissivity >0.2 at the wafer level.

21: Unpatterned beam

22: Faceted field mirror device

24: Faceted pupil mirror device

26: Patterned beam

28: Reflective element

30: Reflective element

40: Diaphragm

41: line

42: line

43: line

44: line

45: line

50: Fixture

60: stud

61: line

62: line

63: line

71:Substrate layer

72: Metallic or semi-metallic layer

73:pore

74: Second material

75:Sacrifice layer

76: Mechanical support layer

77:Mold

78:Dent

79:Mask material

80: Diaphragm assembly

81:Frame

82: column

83:dent

84:Sphere

85:Metal island

86:Honeycomb structure

91: line

92: line

93: line

100: Lithography equipment

210: Radiation Emitting Plasma

211: Source chamber

212:Collector chamber

220:Enclosed structure

221:Open your mouth

500:Controller

B: Radiation beam

C: Target part

CO: radiation collector

d: diameter

E: emissivity

IF: virtual source point

IL: lighting system

M1: Mask alignment mark

M2: Mask alignment mark

MA: Patterned installation

MT: support structure

p: spacing

P1: Substrate alignment mark

P2: Substrate alignment mark

PM: first locator

PS:Projection system

PS1: Position sensor

PS2: Position sensor

PW: Second locator

SO: Source collector module

W: substrate

WT: substrate table

Embodiments of the invention will now be described by way of example only with reference to the accompanying schematic drawings, in which corresponding reference numerals indicate corresponding parts, and in which: Figure 1 depicts a lithography apparatus according to one embodiment of the invention; 2 is a more detailed view of the lithography apparatus; Figure 3 schematically depicts in cross-section a portion of a diaphragm assembly according to an embodiment of the invention; Figure 4 illustrates the angle and emission of incident radiation for diaphragms with different filling factors Figure 5 is a graph showing the relationship between the angle of incident radiation and emissivity for membranes with different distances between pores; Figure 6 is a graph showing the incident radiation for membranes with different metal layers A graph showing the relationship between angle and emissivity; Figure 7 is a cross-sectional view of a membrane of a protective film according to one embodiment of the present invention; Figure 8 is a cross-sectional view of a protective film with circular pores according to one embodiment of the present invention. Plan view of diaphragm; Figure 9 is a plan view of a pellicle separator with square pores according to one embodiment of the present invention; Figures 10 to 13 schematically depict stages of a method of manufacturing a pellicle separator according to one embodiment of the present invention; 14 to 16 schematically depict different stages of an alternative method of manufacturing a pellicle membrane according to one embodiment of the present invention; Different stages of forming pores in the membrane; Figures 21 to 24 schematically depict different stages of an alternative method of forming pores in the membrane of the pellicle according to one embodiment of the invention; Figure 25 is according to one embodiment of the invention An image of metal islands used to form pores in a membrane of a pellicle; FIG. 26 is an image of a metal layer of a membrane of a pellicle according to one embodiment of the present invention; and FIG. 27 is an image of a metal layer of a membrane according to one embodiment of the present invention. An example is the image of a honeycomb structure used to create pores in the diaphragm of a protective film.

Figure 1 schematically depicts a lithography apparatus 100 including a source collector module SO according to one embodiment of the present invention. Device 100 contains:

- An illumination system (or illuminator) IL configured to modulate the radiation beam B (eg EUV radiation).

- A support structure (e.g., mask table) MT constructed to support the patterning device (e.g., mask or reticle) MA and connected to the patterning device configured to accurately position the patterning device The first locator PM;

- a substrate table (e.g., wafer table) WT configured to hold a substrate (e.g., resist-coated wafer) W and connected to a second positioner PW configured to accurately position the substrate; and

- a projection system (e.g., reflective projection system) PS configured to project the pattern imparted to the radiation beam B by the patterning device MA onto a target portion C of the substrate W (e.g., containing one or more dies )superior.

The illumination system IL may include various types of optical components for directing, shaping, or controlling radiation, such as refractive, reflective, magnetic, electromagnetic, electrostatic, or other types of optical components or any combination thereof.

The support structure MT holds the patterning device MA in a manner that depends on the orientation of the patterning device MA, the design of the lithography equipment, and other conditions, such as whether the patterning device is held in a vacuum environment. The support structure MT may use mechanical, vacuum, electrostatic or other clamping techniques to hold the patterning device MA. The support structure MT may be, for example, a frame or a table, which may be fixed or movable as required. The support structure MT may ensure that the patterning device MA is in a desired position relative to the projection system PS, for example.

The term "patterning device" should be interpreted broadly to mean any device that can be used to impart a pattern to the radiation beam B in its cross-section so as to produce a pattern in a target portion C of the substrate W. The pattern imparted to radiation beam B may correspond to specific functional layers in the device produced in target portion C, such as an integrated circuit.

Patterning device MA may be transmissive or reflective. Examples of patterning devices include photomasks, programmable mirror arrays, and programmable liquid-crystal display (LCD) panels. Masks are well known in lithography and include techniques such as binary, intersection Mask types for variable phase shift and attenuated phase shift, as well as various hybrid mask types. One example of a programmable mirror array uses a matrix configuration of small mirrors, each of which can be individually tilted to reflect an incident radiation beam in different directions. The tilted mirrors impart a pattern in the radiation beam reflected by the mirror matrix.

Similar to the illumination system IL, the projection system PS may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic or other types of optics, adapted to the exposure radiation used or to other factors such as the use of a vacuum. components or any combination thereof. A vacuum may be required for EUV radiation because other gases may absorb too much radiation. Therefore, a vacuum environment can be provided to the entire beam path by virtue of the vacuum wall and the vacuum pump.

As depicted here, lithography apparatus 100 is of the reflective type (eg, using a reflective mask).

The lithography apparatus 100 may be of the type having two (dual stages) or more than two substrate tables WT (and/or two or more support structures MT). In this "multi-stage" lithography apparatus, additional substrate stages WT (and/or additional support structures MT) may be used in parallel, or one or more substrate stages WT (and/or one or more supports MT) may be used in parallel. Preparatory steps are performed on the structure MT) while one or more other substrate tables WT (and/or one or more other support structures MT) are used for exposure.

Referring to Figure 1, the illumination system IL receives the extreme ultraviolet radiation beam from the source collector module SO. Methods used to generate EUV light include, but are not necessarily limited to, converting a material into a plasma state with at least one element (such as xenon, lithium, or tin) using one or more emission lines in the EUV range. In one such method, often referred to as laser-produced plasma (LPP), fuel (such as droplets, streams, or clusters of material having the desired line-emitting element) can be produced by irradiating it with a laser beam. And produce the required plasma. The source collector module SO may be part of an EUV radiation system including a laser (not shown in Figure 1) for providing a laser beam that excites the fuel. The resulting plasma emits output radiation (eg EUV radiation) which is collected using a radiation collector disposed in the source collector module. For example, when a _CO2 laser is used to provide the laser beam for fuel excitation, the laser and source collector module SO may be separate entities.

In these cases, the laser is not considered to form part of the lithography apparatus 100 and the radiation beam B is delivered from the laser to the source collector module by means of a beam delivery system including, for example, suitable guide mirrors and/or beam expanders. SO. In other cases, such as when the source is a discharge plasma EUV generator (often referred to as a DPP source), the source may be an integral part of the source collector module SO.

The lighting system IL may include adjusters for adjusting the angular intensity distribution of the radiation beam. Generally speaking, at least an outer radial extent and/or an inner radial extent (commonly referred to as σ outer and σ inner respectively) of the intensity distribution in the pupil plane of the illumination system IL can be adjusted. Additionally, the illumination system IL may include various other components, such as faceted field mirror devices and faceted pupil mirror devices. The illumination system IL can be used to adjust the radiation beam B to have the desired uniformity and intensity distribution in its cross-section.

Radiation beam B is incident on and patterned by a patterning device (eg, mask) MA held on a support structure (eg, mask table) MT. After reflection from the patterning device (eg, reticle) MA, the radiation beam B passes through the projection system PS, which focuses the radiation beam B onto a target portion C of the substrate W. By means of the second positioner PW and the position sensor PS2 (for example an interferometry device, a linear encoder or a capacitive sensor) the substrate table WT can be accurately moved, for example to be positioned in the path of the radiation beam B Different Objectives Part C. Similarly, the first positioner PM and another position sensor PS1 can be used to accurately position the patterning device (eg, mask) MA relative to the path of the radiation beam B. Mask alignment marks M1, M2 and substrate alignment marks P1, P2 may be used to align the patterning device (e.g., Mask) MA and substrate W.

Controller 500 controls the overall operation of lithography apparatus 100 and, in particular, performs operating procedures described further below. Controller 500 may be embodied as a suitably programmed general purpose computer including a central processing unit, volatile and non-volatile storage components, one or more input and output devices (such as a keyboard and screen), to a lithography apparatus Each part of 100 has one or more network connections and one or more interfaces. It should be understood that a one-to-one relationship between the control computer and the lithography apparatus 100 is not necessary. In one embodiment of the present invention, one computer can control multiple lithography apparatuses 100 . In one embodiment of the present invention, multiple networked computers can be used to control one lithography apparatus 100 . The controller 500 may also be configured to control one or more associated process devices and substrate handling devices in a lithography unit or cluster of which the lithography apparatus 100 forms a part. The controller 500 may also be configured to be subordinate to the supervisory control system of the lithography unit or cluster and/or the overall control system of the fab.

Figure 2 shows the lithography apparatus 100 in more detail, which includes the source collector module SO, the illumination system IL and the projection system PS. EUV radiation emitting plasma 210 may be formed from a plasma source. EUV radiation may be generated by a gas or vapor (eg, Xe gas, Li vapor, or Sn vapor), wherein a radiation emitting plasma 210 is generated to emit radiation in the EUV range of the electromagnetic spectrum. In one embodiment, an excited tin (Sn) plasma is provided to generate EUV radiation.

Radiation emitted by the radiation emitting plasma 210 is transferred from the source chamber 211 into the collector chamber 212 .

Collector chamber 212 may include a radiation collector CO. The radiation traversing the radiation collector CO can be focused into the virtual source point IF. The virtual source point IF is commonly referred to as the intermediate focus, and the source collector module SO is configured such that the virtual source point IF is located at or near the opening 221 in the enclosure 220 . The virtual source point IF is an image of the radiation emitting plasma 210 .

The radiation then traverses the illumination system IL, which may include a faceted field mirror device 22 and a faceted pupil mirror device 24 that are Configured to provide a desired angular distribution of the unpatterned beam 21 at the patterning device MA, and a desired uniformity of radiation intensity at the patterning device MA. After reflection of the unpatterned beam 21 at the patterning device MA held by the support structure MT, a patterned beam 26 is formed and imaged by the projection system PS via the reflective elements 28, 30 onto the The substrate table WT is held on the substrate W.

Often more components than shown may be present in the lighting system IL and projection system PS. Furthermore, there may be more mirrors than shown in the figures, for example, there may be 1 to 6 additional reflective elements in the projection system PS than those shown in FIG. 2 .

Alternatively, the source collector module SO may be part of the LPP radiation system.

As depicted in FIG. 1 , in one embodiment, the lithography apparatus 100 includes an illumination system IL and a projection system PS. Illumination system IL is configured to emit radiation beam B. The projection system PS is separated from the substrate table WT by an intervening space. Projection system PS is configured to project the pattern imparted to radiation beam B onto substrate W. The pattern is for EUV radiation radiating beam B.

The space interposed between the projection system PS and the substrate table WT may be at least partially evacuated. The intervention space may be delimited by a solid surface at the location of the projection system PS from which radiation is directed towards the substrate table WT.

In one embodiment, lithography apparatus 100 includes a dynamic air lock. The dynamic air lock contains the diaphragm assembly 80. In one embodiment, the dynamic airlock includes a hollow portion covered by a diaphragm assembly 80 located in the intervening space. The hollow portion is located around the path of radiation. In one embodiment, the lithography apparatus 100 includes a blower configured to flush the interior of the hollow portion with air flow. The radiation travels through the diaphragm assembly before striking the substrate W.

In one embodiment, lithography apparatus 100 includes a diaphragm assembly 80 . As explained above, in one embodiment, the diaphragm assembly 80 is used for dynamic air lock. In this case, the diaphragm assembly 80 acts as a filter for filtering DUV radiation. Additionally or alternatively, in one embodiment, the membrane assembly 80 is a pellicle for the patterning device MA for EUV lithography. The diaphragm assembly 80 of the present invention may be used for a dynamic air lock or for a pellicle or for another purpose such as a spectral purity filter. In one embodiment, diaphragm assembly 80 includes diaphragm 40, which may also be referred to as a diaphragm stack. In one embodiment, the membrane is configured to transmit at least 80% of incident EUV radiation.

In one embodiment, the diaphragm assembly 80 is configured to seal the patterning device MA to protect the patterning device MA from airborne particles and other forms of contamination. Contamination on the surface of the patterning device MA can cause manufacturing defects on the substrate W. For example, in one embodiment, the pellicle is configured to reduce the likelihood that particles may migrate into the step field of the patterning device MA in the lithography apparatus 100 .

If the patterning device MA is not protected, contamination may require the patterning device MA to be cleaned or discarded. Cleaning the patterning device MA interrupts valuable manufacturing time, and discarding the patterning device MA is costly. Replacing the patterning device MA also interrupts valuable manufacturing time.

Figure 3 schematically depicts in cross-section a portion of a diaphragm assembly 80 according to one embodiment of the present invention. Diaphragm assembly 80 series is used for EUV lithography. Diaphragm assembly 80 includes diaphragm 40 . The membrane 40 is emissive for EUV radiation. Of course, the membrane 40 may not have 100% emissivity for EUV radiation. However, the membrane may have an emissivity of, for example, at least 20%. As shown in Figure 3, in one embodiment, membrane 40 is substantially planar. In one embodiment, the plane of membrane 40 is substantially parallel to the plane of patterning device MA.

For example, the diaphragm assembly 80 has a shape such as a square, circular, or rectangular shape. status. The shape of the diaphragm assembly 80 is not particularly limited. The size of the diaphragm assembly 80 is not particularly limited. For example, in one embodiment, the diaphragm assembly 80 has a diameter in the range of about 100 mm to about 500 mm, such as about 200 mm.

As depicted in FIG. 3 , in one embodiment, diaphragm assembly 80 includes frame 81 . Frame 81 is configured to retain diaphragm 40 . Frame 81 provides mechanical stability to diaphragm 40 . Frame 81 is configured to reduce the possibility of diaphragm 40 deforming away from its planar shape. In one embodiment, pretension is applied to the diaphragm 40 during its manufacture. Frame 81 is configured to maintain tension in diaphragm 40 so that diaphragm 40 does not have an undulating shape during use of lithography apparatus 100 . In one embodiment, frame 81 extends along the perimeter of membrane 40 . The outer periphery of the membrane 40 is positioned on top of the frame 81 (view according to figure 3).

As depicted in FIG. 3 , in one embodiment, frame 81 includes a boundary portion directly connected to membrane 40 . The boundary portion of the frame 81 is formed of the second material 74 described later in the present invention. As shown in Figure 3, in one embodiment, the frame 81 further includes an extension that allows the membrane assembly 80 to be more easily secured relative to the patterning device MA. The border portion and the extension portion of the frame 81 can be adhered to each other.

As depicted in FIG. 3 , in one embodiment, diaphragm assembly 80 includes clamp 50 . Clamp 50 is configured to be removably coupled to stud 60 secured relative to pattern device MA. Additional details of the assembly are described in WO 2016079051 A2, in particular in Figures 11 and 28 to 31 and the associated description.

The performance of the diaphragm 40 may deteriorate over time. Deterioration of the diaphragm 40 can result in undesirable reticle imprinting of the pellicle. When relatively high power EUV radiation is incident on the separator 40, the degradation problem of the separator 40 may be more severe. At high temperatures, the membrane 40 may unnecessarily release gas (ie, outgas). For example, membrane 40 may release gases containing oxides. oxide The outgassing can be accelerated by light-induced etching. It is desirable to keep the temperature of the pellicle low to reduce the possibility of outgassing.

As explained above, in one embodiment, the pellicle includes a frame 81 and a diaphragm 40 . Diaphragm 40 is supported by frame 81 . Diaphragm 40 includes a metallic or semi-metallic layer 72 .

Figure 7 shows a cross-section of membrane 40 according to one embodiment of the invention. As shown in FIG. 7 , in one embodiment, membrane 40 includes substrate layer 71 . The substrate layer 71 is used to support the metal or semi-metal layer 72 . As shown in FIG. 7 , in one embodiment, substrate layer 71 is thicker than metallic or semi-metallic layer 72 . Substrate layer 71 is configured to provide structural stability to membrane 40 .

In one embodiment, separator 40 includes an interlayer between substrate layer 71 and metallic or semi-metallic layer 72 . The interlayers are configured to reduce the likelihood of metal or semi-metallic layer 72 breaking. At higher temperatures, this fracture is more likely. In one embodiment, the interlayer includes Mo. In one embodiment, the interlayer has a thickness in the range of about 1 nm to about 2 nm. In one embodiment, the interlayer is formed of a different material than the metallic or semi-metallic layer 72 . In one embodiment, the interlayer is thinner than the metallic or semi-metallic layer 72 .

In one embodiment, the substrate layer 71 includes single crystal Si released from a silicon on insulator (SOI) wafer. In an alternative embodiment, substrate layer 71 includes polysilicon/polycrystalline silicon.

However, the membrane 40 does not necessarily include this substrate layer 71 . For example, in an alternative embodiment, the metallic or semi-metallic layer 72 provides its own structural stability. For example, in one embodiment, the same metal layer 72 forms at least 90% of the total thickness of the separator 40 .

Figure 8 shows a plan view of membrane 40 according to one embodiment of the invention. As shown in Figure 8, in one embodiment, membrane 40 includes apertures 73. Apertures 73 extend through the thickness of membrane 40 . Diaphragm 40 is not continuous. By providing diaphragm 40 to include apertures 73, diaphragm 40 can Transmits a higher proportion of EUV radiation incident on it. This reduces the amount of EUV radiation that can unnecessarily heat membrane 40.

Although FIG. 8 shows a regular distribution of pores 73 on the diaphragm 40, the configuration of the pores 73 is not particularly limited. The pores 73 may be regularly, semi-regularly or randomly distributed on the membrane 40 .

It is desirable for the apertures 73 to be positioned relatively closely together. In one embodiment, the density of pores is at least 5/μm ² . The distance between the centers of adjacent apertures 73 is called pitch p. The spacing p is shown in Figure 8. Generally speaking, a greater density of pores 73 corresponds to a smaller pitch p. For irregularly distributed pores 73 , there may actually be different spacings at different locations on the diaphragm 40 . However, the main spacing can be determined by considering the average distance between the pores 73 over the area of the separator 40 having a size of at least 1 μm ² . A density of 5 pores 73/μm ² corresponds to a spacing p of approximately 450 nm.

By providing a density of pores 73 of at least 5/μm ² , the main spacing p of the pores 73 is less than 1 μm. The distance p is smaller than the wavelength of the radiation emitted by the diaphragm 40 (ie, infrared radiation). The inventors have found that this helps to increase the emissivity E of the diaphragm 40 .

By providing a density of pores 73 of at least 5/μm ² , the emissivity E of the membrane 40 can be kept relatively high. Generally speaking, pores 73 cause the emissivity E of membrane 40 to decrease relative to continuous membrane 40 (ie, a membrane without pores). A higher density of pores 73 (corresponding to a smaller spacing p) is better for higher emissivity E.

FIG. 5 is a graph showing the relationship between the incident radiation of the diaphragm 40 and the angle θ of the emissivity E. Angle θ is the angle of EUV radiation relative to the normal to the plane of membrane 40 . Line 91 is for membrane 40 with a lateral spacing of 200 nm (corresponding to a density of 25 pores/μm ² ). Line 92 is for a separator 40 with the same characteristics, except with a lateral spacing p of 2000 nm (corresponding to a density of approximately 0.25 pores/μm ² ). Line 93 is for a separator 40 with similar characteristics, except with a lateral spacing p of 20000 nm (corresponding to a pore density of about 0.0025 pores/μm ² ). Other main characteristics of the separator 40 are that 75% of the area is formed by pores 73 and the metal layer 72 is formed of Ru with a thickness of 4 nm.

As shown in Figure 5, the emissivity E of the diaphragm 40 increases for reducing the lateral spacing p. A higher emissivity E is desirable so that the diaphragm 40 radiates more of the energy it absorbs, thereby keeping the temperature of the diaphragm 40 reduced. One embodiment of the invention contemplates achieving a reduced temperature of the diaphragm 40 during use.

In one embodiment, the density of pores 73 is at least 20/μm ² . This corresponds to a lateral spacing of approximately 220 nm. As shown in Figure 5, this increases the emissivity E of membrane 40. This in turn helps to keep the diaphragm 40 cooler during use.

In one embodiment, the density of pores is at least 100/μm ² . This corresponds to a lateral spacing p of approximately 100 nm. By providing a density of pores of at least 100/μm ² (ie, a lateral spacing p of at most 100 nm), the light spot from the separator 40 to the substrate W can be reduced. The spot is a proportion of the incident EUV energy scattered on the diaphragm 40 on the substrate W. In one embodiment, the diaphragm 40 is configured such that the light spot to the substrate W is at most 0.25%. This helps provide good quality imaging. If the spot size is too high, this may unnecessarily affect imaging at the level of the substrate W.

The inventors have discovered that the membrane 40 with the apertures 73 acts as a diffraction grating. When the lateral spacing p is at most 150 nm, the spot of normal incident illumination is essentially zero. The inventors have found that, practically speaking, a lower maximum lateral spacing p of approximately 100 nm provides a substantially zero light spot on the substrate W under any illumination mode.

The following table shows examples of spot values for diaphragms 40 with different lateral spacing p and different metal and semi-metallic layers 72 . The material and thickness of metal or semi-metal layer 72 are shown in the table Top of each row. The values in the table are the percentage of light spots facing the substrate W.

As shown in the table, the light spot of the Ru metal layer is often higher than that of the Zr metal layer. This is because Ru is optically stronger than Zr. Other characteristics of the separator 40 on which the calculations in the table are based are that it has a 50 nm thick silicon substrate layer 71 and an open area of 75% (ie, 75% of the area of the separator 40 is formed by pores 73).

In one embodiment, metal layer 72 has a thickness of at least 4 nm. This helps to increase the emissivity E of the diaphragm 40 . FIG. 6 is a graph showing the relationship between the incident radiation of the diaphragm 40 and the angle θ of the emissivity E. There are three lines corresponding to different types of diaphragms 40. For all membranes 40, the pores 73 have a lateral spacing p of approximately 200 nm. The pores 73 form approximately 75% of the area of the membrane 40 . Line 61 is for diaphragm 40 with metal layer 72 formed of Ru with a thickness of 8 nm. Line 62 is for diaphragm 40 having metal layer 72 formed of Ru with a thickness of 4 nm. Line 63 is for diaphragm 40 with metal layer 72 formed of Zr with a thickness of 8 nm.

As shown in FIG. 6 , in general, a thicker metallic or semi-metallic layer 72 increases the emissivity E of the separator 40 . By providing the metal layer 72 with a thickness of at least 4 nm, the emissivity E can be maintained relatively high even in the case where the pores 73 form a relatively high percentage of the total area of the separator 40 .

In one embodiment, metal layer 72 has a thickness of at least 8 nm. As shown in Figure 6, this further increases the emissivity E of membrane 40. Of course, there is a trade-off, i.e. the thicker the gold Metallic layer 72 can result in greater absorption of incident radiation. It is desirable to provide a good balance between the proportion of EUV radiation transmitted by the membrane 40 and the emissivity of the membrane 40 .

4，其中E為用於入射EUV輻射之發射率，且T為透射穿過隔膜40之入射EUV輻射之比例。舉例而言，在一實施例中，發射率E可為約0.2且EUV透射率T可為約95%。此將提供為4之E：(1-T)之比率。在一實施例中，此比率為至少5、至少6、至少7、至少8、至少9或至少10。 For example, in one embodiment, the protective film satisfies

4, where E is the emissivity for incident EUV radiation and T is the proportion of incident EUV radiation transmitted through membrane 40. For example, in one embodiment, the emissivity E can be about 0.2 and the EUV transmittance T can be about 95%. This will provide a ratio of E of 4: (1-T). In one embodiment, the ratio is at least 5, at least 6, at least 7, at least 8, at least 9, or at least 10.

As mentioned above, instead of a metallic layer, a semi-metallic layer 72 may be present. When a semi-metallic layer is provided instead of a metallic layer, it is desirable that the thickness of semi-metallic layer 72 be greater. For example, in one embodiment, the semi-metallic layer has a thickness of at least 10 nm.

As explained further above, when providing a semi-metallic layer 72, it may not be necessary to provide a separate substrate layer 71. However, when no additional substrate layer 71 is provided, the semi-metal layer 72 is expected to be thicker. For example, in one embodiment, the semi-metal layer 72 has a thickness of at least 20 nm.

In one embodiment, pores 73 form at least 50% of the total area of membrane 40 . FIG. 4 is a graph showing the relationship between the incident radiation of the diaphragm 40 and the angle θ of the emissivity E. Different lines 41 to 45 are used for different membranes 40 which are similar except for having different degrees of opening. Line 41 is used for continuous membranes without voids. Line 42 is for a 9% open porous membrane 42 (ie, the pores 73 form 9% of the total area of the membrane 40). Line 43 is used for diaphragm 40 with 36% opening. Line 44 is used for diaphragm 40 with 64% opening. Line 45 is used for diaphragm 40 with 81% opening.

As shown in Figure 4, increasing the openness of membrane 40 decreases the emissivity E. However, increasing the degree of openness increases the EUV transmittance T of the separator 40 . One embodiment of the present invention contemplates increasing the proportion of EUV radiation transmitted by membrane 40.

In one embodiment, the pores form at least 75% of the total area of membrane 40. This can reduce the proportion of EUV radiation that is not transmitted by the membrane 40 by approximately 5 times. Therefore, although the emissivity E is reduced by about a factor of 2, there is still a significant overall benefit. The amount of energy heating the diaphragm 40 is reduced overall.

As shown in Figure 8, in one embodiment, aperture 73 is circular. The diameter of the pore 73 is d. The diameter d can be selected to provide the desired fill factor of the diaphragm 40.

However, the aperture 73 need not be circular. Figure 9 shows an alternative embodiment in which the apertures 73 are square. The aperture 73 has a dimension d. Dimension d can be selected to provide the membrane 40 with a desired fill factor.

The shape of the pores 73 is not particularly limited. In one embodiment, the apertures 73 do not have any regular shape.

One embodiment of the present invention is expected to reduce the amount of EUV radiation absorbed in the membrane 40 . A greater proportion of the incident EUV radiation is transmitted by membrane 40. However, not all additional transmitted EUV radiation is transmitted to substrate W. In particular, apertures 73 diffract radiation such that EUV radiation is transmitted to other areas outside the substrate W. This means that imaging on the substrate W level can maintain high quality.

In one embodiment, membrane 40 is configured to have a specular EUV transmission of at least 80%. In one embodiment, membrane 40 is configured to have a non-specular EUV transmission to substrate W of at most 0.25% (eg, at an angle of less than 4.7 degrees relative to the normal to the plane of membrane 40). In one embodiment, membrane 40 is configured to have an EUV absorption rate of up to 10% in membrane 40 . In one embodiment, membrane 40 is configured to have non-specular EUV transmission of up to 10%, which does not enter the projection optics or substrate W. The total of specular EUV transmittance, non-specular EUV transmittance and absorption is 100%.

The metal of metal layer 72 is not particularly limited. Some metals can oxidize during use. In one embodiment, an oxidation protection layer is provided. For example, an oxide protective layer formed of boron may be provided. The oxidation protection layer is used to reduce oxidation of the metal layer 72 . An oxidation protection layer may be coated on metal layer 72 .

In one embodiment, the metal of metal layer 72 is other than gold. In one embodiment, the metal is a transition metal. In one embodiment, the metal is a transition metal from Group 3 to Group 10. In one embodiment, the metal is a transition metal from period 4 to period 5.

In one embodiment, the metal is a transition metal. The specific transition metal is not particularly limited but may be, for example, Zr, Y, Mo, Cr, Hf, Ir, Mn, Nb, Os, Pd, Pt, Re, Rh, Ru, Ta, Ti, V or W.

In one embodiment, the diaphragm assembly 80 is used as a pellicle or as part of a dynamic air lock. Alternatively, the diaphragm assembly 80 may be used in other filtering areas such as identification, or in beam splitters. In one embodiment, the dynamic air lock is configured to block debris within the lithography apparatus 100 . In one embodiment, a dynamic air lock is positioned between the projection system PS and the substrate W. Dynamic air locking reduces the possibility of particles reaching optical components in or around the projection system PS from or near the substrate W. Similarly, a dynamic air lock protects the lighting system IL. In an alternative embodiment, the dynamic air lock is positioned at a virtual source point IF. For example, a dynamic air lock may be positioned between the source collector module SO and the lighting system IL.

According to an embodiment, a method of manufacturing a pellicle for EUV lithography is provided. 10 to 13 schematically depict different stages of a method of manufacturing a protective film according to an embodiment of the present invention.

As shown in FIG. 10 , in one embodiment, a method includes coating a first material on a second material 74 . The second material 74 is used to form a portion of the frame 81 of the diaphragm assembly 80 point. The present invention will be described with respect to an embodiment in which a first material is used to form the substrate layer 71 . However, as will be described in greater detail subsequently, the first material may instead form a sacrificial layer on which substrate layer 71 is formed.

As shown in FIG. 10 , in one embodiment, the first material forming the substrate layer 71 is coated on all sides (in cross-section) of the second material 74 . The method of depositing the first material on the second material 74 is not particularly limited.

As shown in FIG. 11 , in one embodiment, a method includes patterning the first material at the backside of the second material 74 . The back side is the side opposite the side of the diaphragm 40 forming the diaphragm assembly 80 . The first material is patterned to form a photomask for subsequent etching of the second material 74 .

As shown in FIG. 11 , in one embodiment, the method includes coating a third material to form a metallic or semi-metallic layer 72 of the membrane 40 on the substrate layer 71 . The third material is a metal or semi-metal such as Ru or Zr as mentioned above. The method of coating the third material on the substrate layer 71 is not particularly limited. In one embodiment, the third material is deposited via physical vapor deposition.

As shown in FIG. 12 , in one embodiment, a method includes forming apertures 73 in substrate layer 71 . The pores 73 may be formed with a density of at least 5 μm ² . As shown in Figure 12, in one embodiment, apertures 73 are opened in the combined stack of metallic or semi-metallic layer 72 and substrate layer 71. As shown in the process of FIGS. 11-12 , in one embodiment, a third material (which forms the metallic or semi-metallic layer 72 ) is coated on the substrate layer 71 before forming the apertures 73 . This allows pores 73 to be formed in both metallic or semi-metallic layer 72 and substrate layer 71 in substantially the same process step. This helps provide good uniformity in the shape of the pores 73 in the metallic or semi-metallic layer 72 and the substrate layer 71 . There are various methods for forming apertures 73 in substrate layer 71, as will be described in more detail below.

In one embodiment, the method includes applying a sacrificial layer 75 to a metal or semi-metal on the stack of layer 72 and substrate layer 71 . In one embodiment, the method includes applying a mechanical support layer 76 to the sacrificial layer 75 and the sides of the diaphragm assembly 80 . In a subsequent step, the method includes etching the second material 74, thereby exposing the backside of the membrane 40 (the membrane 40 is formed from the metallic or semi-metallic layer 72 on the substrate layer 71).

The method of etching the second material 74 to expose the diaphragm 40 is not particularly limited. In one embodiment, the second material 74 is etched by performing a wet anisotropic etch. Mechanical support layer 76 is used to provide mechanical support to diaphragm assembly 80 during the step of etching second material 74 . This reduces the likelihood of membrane 40 being damaged (eg, broken) during the etching step. Mechanical support layer 76 is configured to protect the top side of the stack from etchants that remove second material 74 .

In one embodiment, the second material includes silicon. As described above, in one embodiment, the second material may be removed by performing a wet etch. As an alternative, a dry etching process can be used to etch away the second material.

As shown in Figure 13, in one embodiment, the method includes removing the mechanical support layer 76. The method of removing the mechanical support layer 76 is not particularly limited. As shown in Figure 13, in one embodiment, the method includes removing sacrificial layer 75. Sacrificial layer 75 serves to protect the top side of membrane 40 when mechanical support layer 76 is removed. For example, sacrificial layer 75 may protect the top side of membrane 40 from any agents used to remove mechanical support layer 76 . The method of removing the sacrificial layer 75 is not particularly limited.

The sacrificial layer 75 serves as a protective layer to prevent the substrate layer 71 and/or the metal semi-metal layer 72 from being oxidized. The process of removing the sacrificial layer 75 can be performed without damaging or oxidizing the substrate layer 71 or the metal or semi-metal layer 72 .

As shown in FIG. 13 , by removing the mechanical support layer 76 and the sacrificial layer 75 , a separator 40 formed of a metal or semi-metal layer 72 is formed on the substrate layer 71 . Diaphragm 40 extends through The second material forms the boundary portion of the frame 81 .

Modifications of the process described above with reference to Figures 10-13 will now be described.

In one embodiment, the first material forming the substrate layer 71 is a low stress nitride such as nitrided polysiloxane. Low stress nitride resists wet etching. This means that substrate layer 71 does not require an additional sacrificial layer to protect it during the wet etching step (ie, when a large portion of second material 74 is etched away). Low stress nitride is also suitable for forming a hard etch mask on the backside of the assembly, as shown in Figure 11.

However, in one embodiment, the substrate layer 71 includes polysilicon. When the substrate layer 71 is formed of polycrystalline silicon, the first material does not form the substrate layer. What is happening is that when the second material 74 is etched, the first material acts as a sacrificial layer to protect the polycrystalline silicon substrate layer. Accordingly, the method may include the step of coating polysilicon (or other material that will form the substrate layer of separator 40) onto the first material prior to the step of etching second material 74. When the first material is used as a sacrificial layer to protect the substrate layer, the first material may include SiO ₂ .

In the process described above, the third material is coated on the substrate layer 71 before the pores 73 are formed. However, this is not necessarily the case. Figures 14-16 show different stages of an alternative method in which a third material is applied to the substrate layer 71 after the apertures 73 are formed.

In this alternative embodiment, the first material is coated on the second material 74 as shown in FIG. 10 . However, as shown in Figure 14, the backside of the first material is patterned to form a hard mask without depositing a metal or semi-metal layer 72 on the top side.

As shown in FIG. 15 , pores 73 are formed in the substrate layer 71 . This step is performed before providing the metallic or semi-metallic layer 72 . Therefore, pores 73 are not simultaneously formed in metallic or semi-metallic layer 72 .

Then, the sacrificial layer 75 and the mechanical support layer 76 are coated around the substrate layer 71 . This allows the second material to be etched away.

As shown in Figure 16, the mechanical support layer 76 and the sacrificial layer 75 can then be removed in the same manner as described above. As shown in FIG. 16 , this causes the substrate layer 71 to extend through the boundary portion of the frame 81 formed of the second material 74 .

A third material may subsequently be applied to form a metallic or semi-metallic layer 72 of the membrane 40 on the substrate layer 71 . This results in an assembly shown in Figure 13.

Various methods of forming apertures 73 are described below.

Figures 17-20 schematically depict different stages of the process for forming apertures 73. Specifically, Figures 17-20 depict the stages of the nanoimprint lithography process.

As shown in FIG. 17 , in one embodiment, the process of forming the apertures 73 includes pressing the mold 77 onto the photomask material 79 covering the substrate layer 71 . Mold 77 is a basically flat plate containing indentations 78 . The indentations 78 are arranged in a pattern corresponding to the desired aperture locations (ie, the locations where the apertures 73 are intended to be located in the membrane 40). In one embodiment, mold 77 is flexible. In one embodiment, mold 77 is made of a material that is substantially transparent to UV radiation. This allows the photomask material 79 to be irradiated with UV radiation when the mold 77 is coated thereto.

The type of mask material is not particularly limited. In one embodiment, the photomask material is photoresist. Alternatively, the photomask material may be sol-gel.

As shown in Figure 18, by pressing the mold 77 onto the mask material 79, an imprint pattern is formed in the mask material 79 corresponding to the aperture locations. The application of mold 77 results in a contrasting thickness of mask material 79 . Specifically, the photomask material 79 has pillars 82 and recesses 83 . The mold 77 is pressed into the photomask material 79 and then cured via UV radiation to harden/cure the photomask material 79 . Mold 77 is then removed to expose the now cured (solid) and patterned layer.

As shown in Figure 19, in one embodiment, the process of forming the pores 73 includes The mask material 79 is etched to form voids corresponding to the location of the apertures. In one embodiment, reactive ion etching is used to etch mask material 79 . The reactive ion etching process is essentially homogeneous. The etching process causes recesses 83 to be etched away, thereby exposing underlying substrate layer 71 at voids corresponding to the locations of the voids. Pillars 82 are also etched away, but continue to cover substrate layer 71, thereby acting as a photomask.

As shown in FIG. 20 , in one embodiment, the process of forming the aperture 73 includes etching the substrate layer 71 through the void to form the aperture 73 . Pillars 82 of photomask material 79 protect areas of substrate layer 71 from etching. With substrate layer 71 exposed, it is etched away, forming apertures 73 . The aperture 73 is formed at a position corresponding to the indentation 78 of the mold 77 . Mold 77 can be designed to provide a desired pattern of apertures 73 in substrate layer 71 of membrane 40.

The process of nanoimprint lithography makes it possible to finely adjust the periodicity of the pores 73 and the filling factor of the protective film. This can be achieved by appropriately designing the mold 77. Mold 77 is reusable. This helps reduce manufacturing costs.

Figures 21-24 schematically depict different stages of an alternative process for forming apertures 73. As shown in FIG. 21 , in one embodiment, the process of forming the apertures 73 includes depositing spheres 84 on the substrate layer 71 . Spheres 84 are deposited in a pattern corresponding to the desired pore locations. In particular, the center of each sphere 84 is positioned corresponding to the center of the aperture 73 . The process shown in Figures 21 to 24 can be referred to as nanosphere lithography. Nanosphere lithography technology is an alternative technology to nanoimprint lithography. The nanosphere lithography technology shown in Figures 21 to 24 can replace the above steps shown in Figures 12 and 15.

The material of the sphere 84 is not particularly limited. In one embodiment, the spheres are made of polystyrene. In one embodiment, spheres 84 are configured in a hexagonal tight packing layer. In one embodiment, the layer of spheres 84 is a single layer.

As shown in the transition from Figure 21 to Figure 22, in one embodiment, the process includes Reduce the size of sphere 84. For example, the size of sphere 84 may be reduced by etching sphere 84 . For example, plasma etching can be used. The step to reduce the size of the sphere is optional. For example, if the sphere 84 coated on the substrate layer 71 already has a suitable size, there is no need to reduce its size.

As shown in FIG. 22 , in one embodiment, the process of forming the aperture 73 includes coating a third material on the sphere 84 and the substrate layer 71 . The third material is used to form the metallic or semi-metallic layer 72 of the diaphragm 40 . As shown in FIG. 22 , the third material covers the tops of the spheres 84 and covers the portion of the substrate layer 71 between the spheres 84 . The pattern of pores 73 formed in membrane 40 can be controlled by controlling the size and placement of spheres 84 on substrate layer 71

As shown in FIG. 23 , in one embodiment, the process of forming apertures 73 includes removing spheres 84 . This forms an exposed portion of the substrate layer 71 corresponding to the location of the aperture. This results in the third material forming a photomask protecting appropriate portions of substrate layer 71 . In addition to forming the metallic or semi-metallic layer 72, the third material acts as a photomask.

As shown in FIG. 24 , in one embodiment, the process of forming the aperture 73 includes etching the exposed portion of the substrate layer 71 to form the aperture 73 . As an example only, a plasma etching process may be used to remove appropriate portions of substrate layer 71 .

The size of sphere 84 may be selected to provide appropriately sized and configured apertures 73. Generally speaking, the size of sphere 84 corresponds to the size of pores 73 . In one embodiment, the size of spheres 84 is at least 100 nm and at most 10 μm.

Figure 25 is an image of a metal layer in an alternative process for forming aperture 73. In an alternative process for forming holes 73, metal is coated on substrate layer 71. For example, the metal may be silver or gold. Other metals suitable for metal-assisted chemical etching processes may be used. In one embodiment, the metal is initially applied as a substantially uniform layer (ie, having a uniform thickness) throughout on the substrate layer 71.

In one embodiment, the process of forming apertures 73 includes annealing metal to form metal islands 85 on substrate layer 71 . Metal islands 85 are visible in Figure 25. The metal islands 85 are separated from each other. The annealing process results in complete dewetting of the metal. Specifically, the annealing process causes the metal layer to break. As the annealing process continues, the fractures join together to form a network, as seen in Figure 25, leaving individual metal islands 85. When a metal is annealed to a high enough temperature, the metal particles move to an energetically more favorable configuration. This results in the formation of metal islands 85.

In one embodiment, the process of forming apertures 73 includes performing a metal-assisted chemical etching to etch a portion of substrate layer 71 beneath metal islands 85 to form apertures 73 . The metal islands 85 act as a catalyst to etch the substrate layer 71 underneath each metal island 85 (ie, metal droplet).

Figure 26 is an image of a metal or semi-metal layer 72 used in an alternative process for forming apertures 73. In one embodiment, a third material forming the metal or semi-metal layer 72 is coated on the substrate layer 71 . In one embodiment, the process of forming voids 73 includes annealing the third material to form voids in metallic or semi-metallic layer 72 . These gaps are visible in the image in Figure 26. The conditions of the annealing process (eg, temperature, time) can be selected such that voids are formed as shown in FIG. 26 , but the voids are not connected together to form a network of separated metal islands as shown in FIG. 25 . Figure 26 shows the results of partial dewetting of the third material (rather than the complete dewetting shown in Figure 25).

The resulting metal or semi-metal lattice shown in FIG. 26 can be used as an etching mask for etching the substrate layer 71 . In one embodiment, the process of forming the aperture 73 includes etching the substrate layer 71 through the void to form the aperture 73 . The metallic or semi-metallic lattice may then remain as metallic or semi-metallic layer 72, thereby increasing the emissivity of separator 40.

In one embodiment, the annealing and etching steps may be performed instead as shown in Figure 12 steps. Alternatively, the annealing and etching steps may be performed at the end of the method of making the pellicle. For example, the pellicle may be formed from a membrane with a continuous surface (ie, no pores 73). Annealing and etching steps may then be performed to create pores 73 . Therefore, the annealing and etching steps can be performed after the continuous film separator is released.

Figure 27 is an image of honeycomb structure 86 during an alternative process for forming apertures 73. In one embodiment, the process for forming apertures 73 includes providing honeycomb structure 86 as an etching mask. For example, honeycomb structure 86 may be positioned over substrate layer 71 .

In one embodiment, the honeycomb structure 86 includes highly ordered and homogeneous nanopores. For example, in one embodiment, the honeycomb structure includes porous anodized aluminum.

In one embodiment, the process for forming the apertures 73 includes etching the substrate layer 71 through the honeycomb structure 86 to form the apertures 73 . The honeycomb structure 86 is then removed.

For example, the process of providing the honeycomb structure and etching may be performed instead of the steps shown in FIGS. 12 and 15 .

In one embodiment, the honeycomb structure 86 is coated to the stack via an adhesive layer. Alternatively, honeycomb structure 86 may be created during the manufacturing process.

According to an aspect of the present invention, a membrane for a pellicle for EUV lithography is provided, which includes a grating that includes a plurality of holes, apertures or protrusions. The plurality of holes may include, for example, circles, squares, round squares or holes of any shape. The separator may, for example, comprise a primary membrane or primary layer. The thickness of the main film or layer in the grating may range, for example, from 20 nm to 100 nm. In one embodiment, the main film or layer may also be referred to as a core or separator core. Preferably, the grating spacing is less than 200nm to ensure good emissivity. Grating spacing can be defined as the distance between the centers of adjacent holes in the grating. In one embodiment, the main grating pitch is preferably less than 100 nm to ensure low speckle at the wafer level. Smaller grating pitches such as 30nm or less prevent debris particles from landing on the reticle. The membrane of the pellicle for EUV lithography according to any embodiment may comprise a metal layer having a thickness between 4 and 15 nm, or a semi-metal with a thickness in the range of 20 to 80 nm. If the membrane is more open, the metal layer is preferably thicker. In one embodiment, the diaphragm grating has substantially square openings (ie, holes) with a pitch of 30 to 200 nm, such as 100 nm, and a percentage of the opening area or aperture defined by the grating openings of 50 to 90%, Such as 75% opening degree or opening area. A radiating Ru layer with a thickness of approximately 8 nm has an emissivity >0.35. Materials for the pellicle separator may include, for example, an SOI Si separator core combined with a metal layer. In another embodiment, a diaphragm grating comprising SOI Si has a substantially circular or square opening covering 50% to 90% of the diaphragm area, a grating pitch of less than 100 nm, and a metal layer having a thickness in the range of 5 to 15 nm, This metal layer provides low spot light and an emissivity >0.2 at the wafer level.

Although specific reference may be made herein to the use of lithography equipment in IC fabrication, it will be understood that the lithography equipment described herein may have other applications, such as the fabrication of integrated optical systems, conductors for magnetic domain memories, etc. Leading and detecting patterns, flat panel displays, LCDs, thin film magnetic heads, etc. Substrates referred to herein may be processed before or after exposure, for example, in a coating and development system (a tool that typically applies a resist layer to a substrate and develops the exposed resist), a metrology tool, and/or an inspection tool. . Where applicable, the disclosures herein may be applied to these and other substrate processing tools. Additionally, a substrate may be processed more than once, for example, to create a multilayer IC, such that the term "substrate" as used herein may also refer to a substrate that already contains multiple processed layers.

While specific embodiments of the invention have been described above, it should be understood that the invention may be practiced otherwise than as described. For example, various photoresist layers may be replaced by non-photoresist layers that perform the same function. The above description is intended to be illustrative and not restrictive. Therefore, it will be obvious to those skilled in the art that patent applications can be made without departing from the principles set forth below. The invention described may be modified without departing from the scope and scope of the terms.

1. A protective film for EUV lithography, comprising: a frame; and a diaphragm, which is supported by the frame, wherein the diaphragm comprises: a metal or semi-metallic layer, wherein the diaphragm contains pores with a density of at least 5/ ^μm2 .

2. The protective film according to item 1, wherein the density of pores is at least 20/μm ² .

3. The protective film according to item 1, wherein the density of pores is at least 100/μm ² .

4. The protective film according to any one of the preceding items, wherein the separator includes: a substrate layer used to support a metal or semi-metal layer.

5. The protective film of any item 4, wherein the substrate layer comprises silicon obtained from silicon on insulator or polycrystalline silicon.

6. The protective film according to any one of the preceding items, wherein the metal layer has a thickness of at least 4 nm.

7. The protective film according to any one of the preceding items, wherein the metal layer has a thickness of at least 8 nm.

8. The protective film according to any one of the preceding items, wherein the semi-metal layer has a thickness of at least 10 nm.

9. A protective film according to any one of the preceding clauses, wherein the semi-metallic layer forms at least 90% of the total thickness of the separator.

10. The protective film according to any one of the preceding clauses, wherein the semi-metallic layer has a thickness of at least 20 nm.

11. A protective membrane according to any one of the preceding clauses, wherein the pores form at least 50% of the total area of the membrane.

12. A protective film according to any one of the preceding clauses, in which the pores form at least 75% less.

13. The protective film according to any one of the preceding items, wherein the metal is a transition metal from Group 3 to Group 10.

14. The protective film according to any one of the preceding items, wherein the metal is a transition metal from the 4th cycle to the 5th cycle.

15. The protective film according to any one of the preceding items, wherein the metal is selected from the group consisting of: Zr, Y, Mo, Cr, Hf, Ir, Mn, Nb, Os, Pd, Pt, Re, Rh, Ru , Ta, Ti, V and W.

16. The protective film according to any one of the preceding items, wherein the pores are circular or square.

4，其中E為入射EUV輻射之發射率，且T為透射穿過隔膜之入射EUV輻射之比例。 If the protective film in any of the preceding items satisfies

4, where E is the emissivity of incident EUV radiation, and T is the proportion of incident EUV radiation transmitted through the membrane.

18. A protective film according to any one of the preceding clauses, having an emissivity for incident EUV radiation of at least 0.2.

19. A protective film according to any of the preceding clauses configured to transmit at least 95% of incident EUV radiation.

20. A membrane for EUV lithography protective film, comprising: a non-gold metal or semi-metal layer, wherein the membrane contains pores with a density of at least 5/μm ² .

21. A protective film for EUV lithography, comprising: a frame; and a diaphragm as in clause 20, which is supported by the frame.

22. A patterning device assembly for EUV lithography, which includes the protective film according to any one of items 1 to 19 or 21.

23. A dynamic air lock assembly for EUV lithography, which includes the protective film according to any one of claims 1 to 19 or 21.

24. A method of manufacturing a pellicle for EUV lithography, comprising: coating a first material on a second material to form a frame of the pellicle; and coating a third material on a substrate layer of the membrane A metal or semi-metal layer forming a separator of the protective film; and forming pores in the substrate layer at a density of at least 5/ ^μm2 .

25. The method of clause 24, wherein the first material forms the substrate layer.

26. The method of clause 24 or 25, wherein the third material is applied to the substrate layer prior to forming the pores.

27. The method of clause 24 or 25, wherein the third material is applied to the substrate layer after forming the pores.

28. The method of any one of clauses 24 to 27, wherein forming the pores includes: pressing a mold on a photomask material covering the substrate layer to form an imprint pattern corresponding to the location of the pores in the photomask material; etching The photomask material is used to form gaps corresponding to the positions of the holes; and the substrate layer is etched through the gaps to form the holes.

29. The method of any one of clauses 24 to 27, wherein forming the pores includes: depositing spheres on the substrate layer in a pattern corresponding to the positions of the pores; coating the third material on the spheres and the substrate layer; removing The sphere thereby forms an exposed portion of the substrate layer corresponding to the location of the pore; and the exposed portion of the substrate layer is etched to form the pore.

30. The method of any one of clauses 24 to 27, wherein forming the pores comprises: Coating a metal on the substrate layer; annealing the metal to form metal islands on the substrate layer; and performing a metal-assisted chemical etching to etch portions of the substrate layer beneath the metal islands to form pores.

31. The method of any one of clauses 24 to 27, wherein forming the voids includes: annealing the third material to form voids in the metallic or semi-metal layer; and etching the substrate layer through the voids to form the voids.

32. The method of any one of clauses 24 to 27, wherein forming the pores includes: providing a honeycomb structure as an etching mask; etching the substrate layer to form the pores; and removing the honeycomb structure.

33. The method of clause 32, wherein the honeycomb structure comprises porous anodized aluminum.

34. A diaphragm for EUV lithography protective film, the diaphragm comprising a grating containing a plurality of holes.

35. The diaphragm of item 34, wherein the grating pitch is <200nm, preferably <100nm, more preferably <30nm.

36. The membrane of clause 34 or 35, wherein the grating comprises a core having a thickness of between 20 nm and 100 nm.

37. A diaphragm according to any one of clauses 34 to 36, wherein the grating comprises a metal or semi-metal.

38. The diaphragm of any one of clauses 34 to 37, wherein the grating comprises an SOI Si diaphragm core.

39. The membrane of clause 38, wherein the grating further comprises one or more metal layers.

40. A membrane as in clause 38 or 39, wherein the grating comprises substantially circular or square openings and an opening area of between 50% and 90%, preferably between 70% and 80%.

40: Diaphragm

73:pore

d: diameter

p: spacing

Claims (20)

A protective film for EUV lithography, which includes: a frame; and a diaphragm, which is supported by the frame, wherein the diaphragm includes: a metal or semi-metal layer with a uniform thickness, wherein the diaphragm includes a density of At least 5 pores/ ^μm2 . The protective film of claim 1, wherein the density of the pores is at least 20/μm ² . The protective film of claim 1, wherein the density of the pores is at least 100/μm ² . The protective film of any one of claims 1 to 3, wherein the separator includes: a substrate layer used to support the metal or semi-metal layer. The protective film of claim 4, wherein the substrate layer includes silicon obtained from silicon on insulator or polycrystalline silicon. The protective film of any one of claims 1 to 3, wherein the metal layer has a thickness of at least 4 nm. The protective film of any one of claims 1 to 3, wherein the metal layer has a thickness of at least 8 nm. The protective film of any one of claims 1 to 3, wherein the semi-metal layer has a thickness of at least 10 nm. The protective film of any one of claims 1 to 3, wherein the semi-metallic layer forms at least 90% of a total thickness of the separator. The protective film of any one of claims 1 to 3, wherein the semi-metal layer has a thickness of at least 20 nm. The protective film of any one of claims 1 to 3, wherein the pores form at least 50% of a total area of the separator. The protective film of any one of claims 1 to 3, wherein the pores form at least 75% of a total area of the separator. The protective film according to any one of claims 1 to 3, wherein the metal is a transition metal from Group 3 to Group 10. The protective film of any one of claims 1 to 3, wherein the metal is a transition metal of the 4th cycle to the 5th cycle. The protective film of any one of claims 1 to 3, wherein the metal is selected from the group consisting of: Zirconium (Zr), yttrium (Y), molybdenum (Mo), chromium (Cr), hafnium (Hf), iridium (Ir), manganese (Mn), niobium (Nb), osmium (Os), palladium (Pd), Platinum (Pt), rhenium (Re), rhodium (Rh), ruthenium (Ru), tantalum (Ta), titanium (Ti), vanadium (V) and tungsten (W). If the protective film of any one of the requirements 1 to 3 is satisfied,

4, where E is the emissivity of incident EUV radiation, and T is the fraction of incident EUV radiation transmitted through the membrane. The protective film according to any one of claims 1 to 3, which has an emissivity of at least 0.2 for incident EUV radiation. The pellicle of any one of claims 1 to 3, configured to transmit at least 95% of incident EUV radiation. A patterning device assembly for EUV lithography, which includes the protective film according to any one of claims 1 to 18. A dynamic air lock assembly for EUV lithography, which includes the protective film according to any one of claims 1 to 18.