Pellicles for EUV lithography

Abstract

A pellicle for EUV lithography includes a core layer including silicon and having at least one non-oxidized surface, and a cap layer on at least one major surface of the core layer. The cap layer includes carbon and / or boron. The cap layer may be removed before or during an exposure operation.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to European Patent Application No. 22166734.8, filed April 5, 2022, the entire contents of which are incorporated by reference herein.

[0002] The present invention relates to a pellicle, a lithographic apparatus, a method for making a pellicle, a method for performing EUV lithography, and a method for loading a pellicle. [Background technology]

[0003]

[0003] A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. Lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A patterning device, also referred to as a mask or reticle, can be used to generate the circuit pattern formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g. comprising part of, one, or several dies) on the substrate (e.g. a silicon wafer). Typically, transfer of the pattern is by imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. Generally, a single substrate will contain a network of adjacent target portions that are successively patterned.

[0004]

[0004] Lithography is widely recognized as one of the key steps in the manufacture of ICs and other devices and / or structures. However, as the dimensions of features made using lithography decrease, lithography is becoming an even more important factor in enabling miniature ICs or other devices and / or structures to be manufactured.

[0005]

[0005] A theoretical estimate of the limit of pattern printing can be obtained by the Rayleigh criterion for resolution shown in equation (1).

number

[0006]

[0006] To shorten the exposure wavelength and therefore the minimum printable size, it has been proposed to use extreme ultraviolet (EUV) radiation sources. EUV radiation is electromagnetic radiation having a wavelength in the range of 10-20 nm, for example in the range of 13-14 nm. It has further been proposed that EUV radiation having a wavelength less than 10 nm, for example in the range of 5-10 nm, such as 6.7 nm or 6.8 nm, can be used. Such radiation is called extreme ultraviolet or soft x-ray radiation. Possible radiation sources include, for example, laser-produced plasma sources, discharge plasma sources, or sources based on synchrotron radiation provided by electron storage rings.

[0007]

[0007] A lithographic apparatus includes a patterning device (e.g. a mask or a reticle). Radiation is provided through or reflected from the patterning device to form an image on a substrate. A pellicle may be provided to protect the patterning device from airborne particles and other forms of contamination. A pellicle for protecting a patterning device may be referred to as a pellicle. Contamination on a surface of the patterning device may cause manufacturing defects in the substrate. The pellicle may include a frame and a membrane spanning across the frame.

[0008]

[0008] During use of the pellicle, some materials may undesirably outgas from the pellicle, which can cause problems such as an undesirable reduction in the reticle's lifetime and / or reduced imaging quality.

[0009] It would be desirable to provide a pellicle that is more stable and / or has a lower outgassing rate. Summary of the Invention

[0010]

[0010] According to one aspect of the present invention, a pellicle for EUV lithography is provided, the pellicle comprising a core layer comprising silicon and having at least one non-oxidized surface, and a cap layer on at least one major surface of the core layer, the cap layer comprising carbon and / or boron.

[0011]

[0011] According to one aspect of the present invention, an EUV lithography apparatus is provided, the EUV lithography apparatus comprising: a low-pressure environment for an EUV radiation beam path for an exposure operation; and a pellicle disposed in the low-pressure environment, the pellicle including a core layer including a compound including molybdenum embedded in a matrix including silicon, the core layer having at least one non-oxidized surface and exposed to a hydrogen plasma in the low-pressure environment.

[0012]

[0012] According to one aspect of the present invention, there is provided an EUV lithography apparatus comprising: a low pressure environment for an EUV radiation beam path for an exposure operation; and a loading bay for holding a pellicle to be introduced into the low pressure environment, the pellicle comprising a core layer comprising silicon and at least one cap layer comprising carbon and / or boron covering the core layer, the loading bay including an etcher configured to etch away the cap layer of the pellicle to expose the core layer.

[0013]

[0013] According to one aspect of the present invention, there is provided an EUV lithography apparatus comprising: a low pressure environment for an EUV radiation beam path for an exposure operation; a pellicle disposed in the low pressure environment, the pellicle comprising a core layer comprising silicon and a cap layer comprising carbon and / or boron on at least one major surface of the core layer; and a pellicle heater configured to maintain the pellicle at a temperature of at least 500°C.

[0014]

[0014] According to one aspect of the present invention, a method for making a pellicle for EUV lithography is provided, the method comprising depositing a core layer comprising silicon and having at least one non-oxidized surface, and depositing a cap layer on at least one major surface of the core layer, the cap layer comprising carbon and / or boron.

[0015]

[0015] According to one aspect of the present invention, a method for performing EUV lithography is provided, the method including projecting a beam of EUV radiation onto a substrate through a low-pressure environment in an exposure operation, the EUV radiation beam passing through a pellicle disposed in the low-pressure environment, the pellicle including a core layer including a compound including molybdenum embedded in a matrix including silicon, the core layer having at least one non-oxidized surface and exposed to a hydrogen plasma in the low-pressure environment.

[0016]

[0016] According to one aspect of the present invention, there is provided a method for loading a pellicle into a low pressure environment of an EUV lithography apparatus, the method including holding a pellicle in a loading bay to be introduced into the low pressure environment, the pellicle including a core layer comprising silicon and at least one cap layer comprising carbon and / or boron covering the core layer, etching away the cap layer of the pellicle to expose the core layer, and moving the pellicle from the loading bay to the low pressure environment for an exposure operation.

[0017]

[0017] According to one aspect of the present invention, there is provided a method for performing EUV lithography, the method including projecting a beam of EUV radiation onto a substrate through a low pressure environment in an exposure operation, the EUV radiation beam passing through a pellicle disposed in the low pressure environment, the pellicle including a core layer comprising silicon and a cap layer comprising carbon and / or boron on at least one major surface of the core layer, and maintaining the pellicle at a temperature of at least 500°C. [Brief description of the drawings]

[0018]

[0018] Some embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which like reference symbols indicate corresponding parts, in which:

[0019] [Figure 1] FIG. 1 depicts a lithographic apparatus according to one embodiment of the invention. [Diagram 2]

[0020] FIG. 2 shows a more detailed view of the lithographic apparatus. [Diagram 3]

[0021] FIG. 3 shows a schematic cross-section of a portion of a pellicle according to one embodiment of the invention. [Figure 4]

[0022] FIG. 4 illustrates a schematic of a pellicle according to one embodiment of the present invention. [Diagram 5]

[0023] FIG. 5 illustrates a schematic of a pellicle according to one embodiment of the present invention. [Figure 6]

[0024] FIG. 6 depicts a schematic diagram of a lithographic apparatus according to one embodiment of the invention. [Figure 7]

[0025] FIG. 7 depicts a schematic diagram of a lithographic apparatus according to one embodiment of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020]

[0026] 1 shows a schematic diagram of a lithographic apparatus 100 including a source collector module SO according to an embodiment of the present invention. - an illumination system (or illuminator) IL configured to condition a radiation beam B (e.g. EUV radiation); a support structure (e.g. mask table) MT constructed to support a patterning device (e.g. mask or reticle) MA and coupled to a first positioner PM configured to accurately position the patterning device; and - a substrate table (e.g. a wafer table) WT constructed to hold a substrate (e.g. a resist-coated wafer) W and coupled to a second positioner PW configured to accurately position the substrate; and a projection system (eg a refractive projection lens system) PS configured to project a pattern imparted to a radiation beam B by a patterning device MA onto a target portion C (eg comprising one or more dies) of a substrate W.

[0021]

[0027] The illumination system IL may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic or other types of optical components, or any combination thereof, to guide, shape or control radiation.

[0022]

[0028] The support structure MT holds the patterning device MA in a manner that depends on the orientation of the patterning device, the design of the lithographic apparatus, and other conditions, such as whether or not 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 at a desired position, for example with respect to the projection system PS.

[0023]

[0029] The term "patterning device" should be interpreted broadly to refer to any device that can be used to impart a radiation beam B with a pattern in its cross-section so as to create a pattern in a target portion C of a substrate W. The pattern imparted to the radiation beam B will correspond to a particular functional layer in a device being created in the target portion C, such as an integrated circuit.

[0024]

[0030] The patterning device MA may be of a transmissive or reflective type. Examples of patterning devices include masks, programmable mirror arrays, and programmable liquid crystal display (LCD) panels. Masks are well known in lithography, and include mask types such as binary, alternating phase-shift, and attenuated phase-shift, as well as various hybrid mask types. An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted so as to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern to the radiation beam that is reflected by the mirror matrix.

[0025]

[0031] The projection system PS, like the illumination system IL, may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic or other types of optical components as appropriate for the exposure radiation being used or other factors such as the use of a vacuum. It may be desirable to use a vacuum for EUV radiation, as other gases may absorb too much radiation. Therefore, a vacuum environment may be provided throughout the beam path using a vacuum wall and vacuum pumps.

[0026]

[0032] As here depicted, lithographic apparatus 100 may be of a reflective type (eg, employing a reflective mask).

[0027]

[0033] Lithographic apparatus 100 may be of a type having two (dual stage) or more substrate tables WT (and / or two or more support structures MT). In such a "multi-stage" lithographic apparatus, the additional substrate tables WT (and / or additional support structures MT) may be used in parallel, or preparation steps may be performed on one or more substrate tables WT (and / or one or more support structures MT) while one or more further substrate tables WT (and / or one or more further support structures MT) are used for exposure.

[0028]

[0034] Referring to FIG. 1, the illumination system IL receives an extreme ultraviolet radiation beam from a source collector module SO. Methods for generating EUV light include, but are not necessarily limited to, converting a material into a plasma state having at least one element, such as xenon, lithium, or tin, and having one or more emission lines in the EUV range. In one such method, often referred to as laser-produced plasma ("LPP"), a fuel, such as a droplet, stream, or cluster of a material having the required line-emitting element, can be generated by irradiating the fuel with a laser beam. The source collector module SO may be part of an EUV radiation system that includes a laser (not shown in FIG. 1) for providing a laser beam that excites the fuel. The resulting plasma emits output radiation (e.g., EUV radiation), which is collected using a radiation collector disposed in the source collector module. The laser and the source collector module SO may be separate components, for example when a CO2 laser is used to provide the laser beam for fuel excitation.

[0029]

[0035] In such a case, the laser is not considered to form part of lithographic apparatus 100, and the radiation beam B is delivered from the laser to the source collector module SO using a beam delivery system including, for example, suitable directing mirrors and / or beam expanders. In other cases, the source may be an integral part of the source collector module SO, for example when the source is a discharge produced plasma EUV generator (often referred to as a "DPP source").

[0030]

[0036] The illumination system IL may include an adjuster for adjusting the angular intensity distribution of the radiation beam. Typically, at least the outer and / or inner radial extent (commonly referred to as -outer and -inner, respectively) of the intensity distribution in a pupil plane of the illumination system IL may be adjusted. In addition, the illumination system IL may include various other components, such as facetted field and pupil mirror devices. The illumination system IL may be used to condition the radiation beam B to have a desired uniformity and intensity distribution in its cross-section.

[0031]

[0037] The radiation beam B is incident on a patterning device (e.g. mask) MA, which is held on a support structure (e.g. mask table) MT, and is patterned by the patterning device MA. After reflecting from the patterning device (e.g. mask) MA, the radiation beam B passes through a projection system PS, which focuses the radiation beam B onto a target portion C of the substrate W. Using a second positioner PW and a position sensor PS2 (e.g. an interferometer device, a linear encoder or a capacitive sensor), the substrate table WT may be accurately moved, for example to position different target portions C in the path of the radiation beam B. Similarly, the patterning device (e.g. mask) MA may be accurately positioned with respect to the path of the radiation beam B using the first positioner PM and a further position sensor PS1. The patterning device (e.g. mask) MA and substrate W may be aligned using mask alignment marks M1 and M2 and substrate alignment marks P1 and P2.

[0032]

[0038] The controller 500 controls the overall operation of the lithographic apparatus 100 and in particular executes the operational processes described below. The controller 500 may be embodied as a suitably programmed general purpose computer comprising a central processing unit, volatile and non-volatile storage means, one or more input and output devices such as a keyboard and a screen, one or more network connections, one or more interfaces to various parts of the lithographic apparatus 100. It will be appreciated that a one-to-one relationship between the control computer and the lithographic apparatus 100 is not necessary. In an embodiment of the invention, one computer may control multiple lithographic apparatuses 100. In an embodiment of the invention, multiple computers connected to a network may be used to control one lithographic apparatus 100. The controller 500 may be configured to control one or more associated processing devices and substrate handling devices in a lithocell or cluster of which the lithographic apparatus 100 forms a part. The controller 500 may be configured to be subordinate to a supervisory control system of the lithocell or cluster and / or to an overall control system of the fab.

[0033]

[0039] 2 shows lithographic apparatus 100 in more detail, including a source collector module SO, an illumination system IL, and a projection system PS. An EUV radiation emitting plasma 210 may be formed by a plasma source. The EUV radiation may be generated by a gas or vapor, such as Xe gas, Li vapor, or Sn vapor, from which the radiation emitting plasma 210 is generated to emit radiation in the EUV range of the electromagnetic spectrum. In an embodiment, excited tin (Sn) is provided to generate the EUV radiation.

[0034]

[0040] Radiation emitted by the radiation emitting plasma 210 passes from the source chamber 211 into the collector chamber 212 .

[0035]

[0041] The collector chamber 212 may include a radiation collector CO. Radiation passing through the radiation collector CO may be focused at a virtual source point IF. The virtual source point IF is commonly referred to as an intermediate focus, and the source collector module SO is positioned such that the virtual source point IF is at or near an opening 221 of the enclosure structure 220. The virtual source point IF is an image of the radiation emitting plasma 210.

[0036]

[0042] The radiation then passes through an illumination system IL, which may include a faceted field mirror device 22 and a faceted pupil mirror device 24 arranged to provide a desired angular distribution of the unpatterned beam 21 at the patterning device MA as well as a desired uniformity of the radiation intensity at the patterning device MA. Upon reflection of the unpatterned beam 21 off the patterning device MA, held by the support structure MT, a patterned beam 26 is formed, which is imaged by the projection system PS via reflective elements 28, 30 onto a substrate W held by a substrate table WT.

[0037]

[0043] In general, there may be more elements in the illumination system IL and projection system PS than are shown, and furthermore there may be more mirrors than are shown, for example there may be one to six additional reflective elements in the projection system PS than are shown in Figure 2.

[0038]

[0044] Alternatively, the source collector module SO may be part of an LPP radiation system.

[0039]

[0045] As shown in Figure 1, in an embodiment, lithographic apparatus 100 includes an illumination system IL and a projection system PS. The illumination system IL is configured to emit a radiation beam B. The projection system PS is separated from a substrate table WT by an intervening space. The projection system PS is configured to project a pattern imparted to the radiation beam B onto a substrate W. This pattern is for EUV radiation in the radiation beam B.

[0040]

[0046] The intervening space between the projection system PS and the substrate table WT may be at least partially evacuated, The intervening space may be bounded at the location of the projection system PS by a solid surface from which the used radiation is directed towards the substrate table WT.

[0041]

[0047] In one embodiment, the lithographic apparatus 100 includes a dynamic gas lock. The dynamic gas lock includes a pellicle 80. In one embodiment, the dynamic gas lock includes a hollow portion covered by the pellicle 80 located in an intervening space. The hollow portion is located around the path of the radiation. In one embodiment, the lithographic apparatus 100 includes a gas blower configured to flush the inside of the hollow portion with a flow of gas. The radiation travels through the pellicle before impinging on the substrate W.

[0042]

[0048] In one embodiment, the lithographic apparatus 100 includes a pellicle 80. As explained above, in one embodiment, the pellicle 80 is for a dynamic gas lock. In this case, the pellicle 80 acts as a filter to filter out IR radiation and / or DUV radiation. Additionally or alternatively, in one embodiment, the pellicle 80 is a pellicle for a patterning device MA for EUV lithography. The pellicle 80 of the present invention can be used for other purposes, such as a dynamic gas lock or pellicle, or a spectral purity filter. In one embodiment, the pellicle 80 includes a membrane 40, also referred to as a membrane stack. In one embodiment, the membrane is configured to transmit at least 80% of the incident EUV radiation.

[0043]

[0049] In one embodiment, pellicle 80 is configured to enclose the patterning device MA to protect it from airborne particles and other forms of contamination that can cause manufacturing defects on the substrate W. For example, in one embodiment, pellicle 80 is configured to reduce the likelihood of particles migrating into the stepping field of patterning device MA in lithographic apparatus 100.

[0044]

[0050] If the patterning device MA is left unprotected, contamination may necessitate cleaning or discarding the patterning device MA, cleaning the patterning device MA is an interruption in valuable production time, discarding the patterning device MA is costly, and replacing the patterning device MA also interrupts valuable production time.

[0045]

[0051] Figure 3 shows a schematic cross-section of a portion of a pellicle 80 according to an embodiment of the present invention. Pellicle 80 is for EUV lithography. Pellicle 80 comprises membrane 40. Membrane 40 is transparent to EUV radiation. Of course, membrane 40 may not transmit 100% of the EUV radiation incident thereon. 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.

[0046]

[0052] Pellicle 80 has a shape such as, for example, a square, a circle, or a triangle. The shape of pellicle 80 is not particularly limited. The size of pellicle 80 is not particularly limited. For example, in one embodiment, pellicle 80 has a diameter in the range of about 100 mm to about 500 mm, for example, about 200 mm.

[0047]

[0053] As shown in FIG. 3, in one embodiment, the pellicle 80 comprises a frame 81. The frame 81 is configured to hold the membrane 40. The frame 81 provides mechanical stability to the membrane 40. The frame 81 is configured to reduce the possibility of the membrane 40 deforming from its planar shape. In one embodiment, the membrane 40 is pre-tensioned during its manufacture. The frame 81 is configured to maintain tension in the membrane 40 so that the membrane 40 does not have a wavy shape during use of the lithographic apparatus 100. In one embodiment, the frame 81 extends along the periphery of the membrane 40. The periphery of the membrane 40 is positioned on top of the frame 81 (according to the view of FIG. 3).

[0048]

[0054] As shown in Figure 3, in one embodiment, frame 81 includes a border portion that is directly connected to membrane 40. The border portion of frame 81 is formed from second material 74, which will be described later in this disclosure. As shown in Figure 3, in one embodiment, frame 81 further includes an extension portion that makes it easier to secure pellicle 80 relative to patterning device MA. The border portion and the extension portion of frame 81 may be adhered to each other.

[0049]

[0055] 3, in one embodiment, the pellicle 80 includes a fixture 50. The fixture 50 is arranged to be removably coupled to a stud 60 fixed relative to the pattern device MA. Further details of the assembly are described in WO2016079051A2, particularly Figures 11 and 28-31 and the associated description.

[0050]

[0056] Figure 4 is a schematic diagram of a pellicle 80 according to an embodiment of the invention. Figure 4 shows a portion of the membrane 40 of the pellicle 80. The pellicle 80 is for EUV lithography. For example, the pellicle 80 may comprise part of a dynamic gas lock of the lithographic apparatus 100 and / or such a pellicle 80 may be used in combination with a patterning device MA. Figure 4 shows a cross section of the membrane 40.

[0051]

[0057] As shown in FIG. 4, in one embodiment, pellicle 80 includes core layer 41. Core layer 41 forms the body of membrane 40 of pellicle 80. Core layer 41 is configured to be transparent to EUV radiation. Core layer 41 is configured to be a barrier to particles. In one embodiment, core layer 41 has at least one non-oxidized surface. In one embodiment, both major surfaces of core layer 41 are non-oxidized. Alternatively, one of the major surfaces is oxidized and the other is non-oxidized. Core layer 41 includes silicon. In one embodiment, core layer 41 includes SiN. Additionally or alternatively, core layer 41 includes elemental silicon, Si. Elemental silicon may be more transparent to EUV radiation compared to SiN. Embodiments of the present invention are expected to increase the percentage of EUV radiation that is transmitted through pellicle 80.

[0052]

[0058] Additionally or alternatively, the core layer 41 may include other forms of silicon. For example, in one embodiment, the core layer 41 includes ZrSi2. In one embodiment, the core layer 41 includes SiC. In one embodiment, the core layer 41 includes ZrSi2N x In one embodiment, the core layer 41 comprises polysilicon.

[0053]

[0059] As shown in FIG. 4, in one embodiment, the pellicle 80 includes a cap layer 42. The cap layer 42 is on at least one major surface of the core layer 41. The core layer 41 has two major surfaces. The major surfaces are planar. In the configuration shown in FIG. 4, the cap layer 42 is provided on both major surfaces of the core layer 41. In an alternative embodiment, the cap layer 42 is provided on only one major surface of the core layer 41. The cap layer 42 may be in direct contact with the core layer 41. There is substantially no intermediate layer between the cap layer 42 and the core layer 41. The core layer 41 is made of a substantially homogenous material that is not layered. The cap layer 42 has a different composition than the core layer 41.

[0054]

[0060] The cap layer 42 reduces the likelihood of native oxide growth on the surface of the core layer 41. The cap layer 42 may reduce the likelihood of SiO and / or SiN and / or SiON formation on the surface of the core layer 41. The SiON layer may be one or more SiO x , SiN y and SiO x N y Such material formed on the surface of core layer 41 may result in undesirable outgassing within lithographic apparatus 100. One embodiment of the present invention is expected to reduce outgassing from pellicle 80 within lithographic apparatus 100.

[0055]

[0061] Core layer 41 exposed to the atmosphere may develop a native SiON layer on its surface. This layer may have a thickness of about 1.5 nm in areas. In use in lithographic apparatus 100, pellicle 80 may be exposed to intense EUV radiation, high temperatures and / or hydrogen plasma. In part due to these conditions, silicon may be removed from pellicle 80, particularly from the native SiON layer on the surface of core layer 41. Relocation of silicon is undesirable in lithographic apparatus 100. For example, silicon that outgases from pellicle 80 may adhere to features on patterning device MA and cause imaging errors. This may result in premature replacement of patterning device MA. Silicon in lithographic apparatus 100 may also deposit on reflective surfaces that may potentially disrupt imaging quality and / or reduce throughput by absorbing EUV radiation used for imaging. Cap layer 42 may reduce the outgassing rate of silicon from pellicle 80.

[0056]

[0062] In one embodiment, the cap layer 42 includes carbon. Additionally or alternatively, the cap layer 42 includes boron. In the lithographic apparatus 100, the carbon and / or boron can be removed from the pellicle 80. Carbon and boron can be more easily cleaned in the environment of the lithographic apparatus 100 compared to silicon. Carbon and boron are less likely to deposit on reflective surfaces in the lithographic apparatus 100 because they are easily etched away in the hydrogen plasma ambient in the lithographic apparatus 100. Outgassing of carbon and boron does not pose the same level of problems as outgassed silicon.

[0057]

[0063] In one embodiment, the cap layer 42 has a thickness of at most 10 nm. The thickness of the cap layer 42 is the dimension of the cap layer 42 measured in a direction perpendicular to the plane of the core layer 41. A thinner thickness of the cap layer 42 can reduce the extent to which the cap layer 42 reduces the proportion of EUV radiation transmitted through the pellicle 80. In one embodiment, the cap layer 42 has a thickness of at most 50 nm, optionally at most 20 nm, optionally at most 10 nm, optionally at most 5 nm, optionally at most 2 nm. A sufficiently thin cap layer 42 can remain in place during use of the pellicle 80 in the lithographic apparatus 100 without unduly reducing the transmission of EUV radiation through the pellicle 80.

[0058]

[0064] In one embodiment, the core layer 41 includes molybdenum. For example, the core layer 4 can include a compound 43 that includes molybdenum. The compound 43 can be MoSi2 and / or Mo5Si3. It is not necessary that the compound includes molybdenum. In one embodiment, the compound can be a SiC, such as SiC. x C y In one embodiment, the compound 43 is embedded in a matrix 44 that includes silicon. The matrix 44 may include SiN and / or elemental Si. In one embodiment, the compound 43 is formed as a crystal. In one embodiment, the core layer 41 is comprised of MoSi2 and / or Mo5Si3 crystals embedded in a matrix 44 of SiN and / or Si.

[0059]

[0065] As mentioned above, it is possible for the cap layer 42 to remain part of the pellicle 80 covering the core layer 41 during use of the lithographic apparatus 100. Alternatively, the cap layer 42 may be removed before the pellicle 80 is used in an exposure operation or during one or more exposure operations. The cap layer 42 may be a sacrificial layer that is removed to provide a bare core layer comprising silicon. After the cap layer 42 is at least partially removed, the core layer 41 is exposed to the environment within the lithographic apparatus 100. Such a pellicle 80 without the cap layer 42 is shown in FIG. 5. FIG. 5 shows the core layer 42 exposed to a hydrogen plasma 45 in the lithographic apparatus 100.

[0060]

[0066] Figure 6 illustrates diagrammatically a lithographic apparatus 100 according to an embodiment of the present invention. As illustrated in Figure 6, optionally, the lithographic apparatus 100 includes a low-pressure environment 101 (sometimes also referred to as a vacuum environment). The low-pressure environment 101 may be substantially sealed from the external atmosphere. The low-pressure environment 101 may be connected to a low-pressure source to maintain a vacuum within the low-pressure environment 101.

[0061]

[0067] 6, optionally the source collector module SO, illumination system IL, patterning device MA (supported by support structure MT), projection system PS and substrate W (supported on a substrate table WT) may be located within a low pressure environment 101. A hydrogen plasma 45 may be present in the low pressure environment.

[0062]

[0068] In one embodiment, a pellicle 80 is placed in a low pressure environment 101. The pellicle can include a core layer 41 including a compound 42 including molybdenum embedded in a matrix 44 including silicon. As shown in FIG. 5, in one embodiment, the core layer 41 is exposed to a hydrogen plasma 45 in the low pressure environment 101. The removal rate of silicon from the core layer 41 can be lower than the removal rate of silicon from a native SiON layer. For example, bare silicon can be etched as much as 10 times slower than SiO and SiN compounds. It is expected that embodiments of the present invention will reduce the removal rate of silicon from the pellicle 80.

[0063]

[0069] A native SiON layer is less likely to form on the surface of the core layer 41 when the pellicle 80 is in the low pressure environment 101 than when the pellicle 80 is exposed to the ambient atmosphere. The low pressure environment 101 may include a hydrogen plasma 45. The hydrogen plasma 45 forms a reducing atmosphere, thereby reducing the likelihood of oxide formation on the surface of the core layer 41. The core layer 41 exposed to the hydrogen plasma 45 may remain stably exposed in the low pressure environment 101.

[0064]

[0070] The cap layer 42 is removed to expose the core layer 41 to the low pressure environment 101. In one embodiment, the cap layer is at least partially, and optionally completely, removed before the pellicle 80 is introduced into the low pressure environment 101. As shown in FIG. 6 , in one embodiment, the lithographic apparatus 100 includes a loading bay 102. The loading bay 102 may be referred to as a load lock. The loading bay 102 is for holding the pellicle 80 to be introduced into the low pressure environment 101. The pellicle 80 is placed in the loading bay 102 before the pellicle 80 is moved to the low pressure environment 101. The loading bay 102 allows components to be inserted into the low pressure environment 101 without unduly increasing the pressure in the low pressure environment 101.

[0065]

[0071] When the pellicle 80 is introduced into the loading bay 102, the pellicle 80 may be combined with, for example, a patterning device MA. The pellicle 80 may be combined with other components, for example, for a dynamic gas lock. The pellicle 80 may be introduced into the loading bay 102 from an external environment. The external environment may be at a higher pressure than the low pressure environment 101. For example, the external environment may be at atmospheric pressure. When the pellicle 80 is in the loading bay 102, the loading bay is sealed and the pressure in the loading bay 102 is reduced toward the pressure in the low pressure environment 101. The loading bay 102 may then be in spatial communication with the low pressure environment 101, for example, by opening a window between the loading bay 102 and the low pressure environment 101. The pellicle 80 is moved from the loading bay 102 to the low pressure environment 101.

[0066]

[0072] In one embodiment, the cap layer 42 is at least partially, and optionally completely, removed from the pellicle 80 when the pellicle 80 is in the loading bay 102. As shown in FIG. 6, in one embodiment, the loading bay 102 includes an etcher 103. It is believed that the etcher 103 etches away the cap layer 42 of the pellicle 80 to expose the core layer 41. The cap layer 42 may be etched away when the pressure in the loading bay 102 is reduced to a pressure similar to the pressure in the low pressure environment 101. This can reduce the likelihood of a native SiON layer forming on the surface of the core layer 41 that is exposed after the cap layer 42 is etched away. Alternatively, the cap layer 42 can be removed before the pressure in the loading bay 102 is reduced or while the pressure in the loading bay 102 is reduced. In one embodiment, the loading bay 102 includes a hydrogen plasma. A reducing atmosphere in the loading bay 102 can reduce the likelihood of a native SiON layer forming on the core layer 41.

[0067]

[0073] The cap layer 42 includes carbon and / or boron. In this embodiment, the cap layer 42 is made of carbon and / or boron. Carbon and boron can be easily etched with hydrogen plasma. In one embodiment, the etcher 103 includes a plasma source configured to provide hydrogen plasma for etching the cap layer 42. In one embodiment, the etcher 103 includes an ionizing radiation source. The ionizing radiation source is configured to ionize hydrogen gas in the loading bay 102 to generate hydrogen plasma 45. In one embodiment, the ionizing radiation source is configured to output microwave radiation. The microwave radiation easily ionizes the hydrogen gas. The ionizing radiation source can accelerate the etching of the cap layer 42. In one embodiment, the ionizing radiation source is controlled to move a beam of ionizing radiation. This can help improve the uniformity of the exposure of the pellicle 80 to the hydrogen plasma 45.

[0068]

[0074] In one embodiment, the etcher 103 includes an excitation radiation source. The excitation radiation source is configured to output excitation radiation, i.e., radiation for exciting the material of the cap layer 42. In one embodiment, the excitation radiation source is configured to output EUV radiation and / or DUV radiation. The excitation radiation may excite the material of the cap layer 42 and cause the material of the cap layer 42 to outgas. The power of the excitation radiation source may be controlled to control the etch rate of the cap layer 42. The excitation radiation has a short wavelength to excite the material.

[0069]

[0075] As a further alternative, one or more chemicals may be used to remove the cap layer 42 in the loading bay 102. The patterning device MA is more robust with respect to ionizing and exciting radiation.

[0070]

[0076] It is not necessary to completely remove the cap layer 42 before introducing the pellicle 80 into the low pressure environment 101. In one embodiment, at least a portion, and optionally all, of the cap layer 42 remains on the pellicle 80 when the pellicle 80 is introduced into the low pressure environment 101 for use in an exposure operation. In one embodiment, the cap layer 42 is partially or completely removed while the pellicle 80 is in the low pressure environment 101. For example, the cap layer 42 may be etched away during an exposure operation to expose a first substrate W. Image quality for the first substrate W may be slightly adversely affected by the presence of the cap layer 42. Once the cap layer 42 is removed, image quality is not degraded for subsequent substrates W. The cap layer 42 may be gradually reduced in thickness for the first exposed substrate or substrates W. The cap layer 42 may be easily etched away in the low pressure environment 101 due to the presence of the hydrogen plasma 45, the EUV radiation, and the resulting high temperatures.

[0071]

[0077] It is not necessary for the cap layer 42 to be partially or completely removed prior to entering the low pressure environment 101 or while in the low pressure environment 101. In one embodiment, the cap layer 42 may remain on the portion of the pellicle 80 covering the core layer 41 during use of the pellicle 80 in the low pressure environment 101. As discussed above, a sufficiently thin cap layer 41 does not significantly reduce the percentage of EUV radiation that is transmitted through the pellicle 80. The cap layer 42 may be a permanent cap layer on the core layer 41.

[0072]

[0078] FIG. 7 is a schematic diagram of a lithographic apparatus 100, according to one embodiment of the invention. As shown in FIG. 7, in one embodiment, the lithographic apparatus 100 includes a pellicle heater 104. The pellicle heater 104 is configured to maintain the pellicle 80 at a temperature of at least 500° C., optionally at least 600° C. and 700° C. By maintaining the pellicle 80 at a high temperature, etching of carbon and / or boron in the cap layer 42 may be reduced. At high temperatures, the etching rate of carbon and / or boron decreases to a rate at which the cap layer 42 may remain part of the pellicle 80 throughout the life of the patterning apparatus MA.

[0073]

[0079] In one embodiment, the pellicle heater 104 includes a heating radiation source. The heating radiation source is configured to output heating radiation for heating the low pressure environment 101. The heating radiation source is configured to pump heat into the low pressure environment 101 to maintain the pellicle 80 at an elevated temperature. For example, in one embodiment, the heating radiation source is configured to provide infrared radiation for heating the pellicle 80. As shown in FIG. 7, in one embodiment, the pellicle heater 104 is disposed adjacent to the pellicle 80. Alternatively, the pellicle heater 104 may be disposed elsewhere within the low pressure environment 101.

[0074]

[0080] Additionally or alternatively, pellicle heater 80 may comprise an ohmic heater configured to pass an electric current through pellicle 80, such as through membrane 40 of pellicle 80. The electric current heats or maintains the temperature of pellicle 80.

[0075]

[0081] Additionally or alternatively, in one embodiment, the pellicle heater 104 includes a thermionic heater configured to provide charged particles. For example, in one embodiment, the thermionic heater includes one or more electron guns for heating the membrane 40 of the pellicle 80.

[0076]

[0082] As discussed above, in one embodiment, a pellicle 80 is fabricated having a core layer and at least one cap layer 42 comprising carbon and / or boron. In one embodiment, a method of fabricating a pellicle 80 includes depositing a core layer 41 comprising silicon. For example, the core layer 41 may be deposited by a sputtering process. The method may further include depositing a cap layer 42 on at least one major surface of the core layer 41.

[0077]

[0083] According to one embodiment, the core layer 41 is deposited in a vacuum. The cap layer 42 is then deposited while maintaining the vacuum. By maintaining the vacuum, the possibility of a native SiON layer forming on the surface of the core layer 41 prior to the location of the cap layer 42 is reduced. In one embodiment, the cap layer 42 is deposited on the core layer 41 immediately after the deposition of the core layer 41.

[0078]

[0084] Additionally or alternatively, any native SiON layer formed on the surface of the deposited core layer 41 can be etched away prior to depositing the cap layer 42. In one embodiment, an etchant is used to etch away any native SiON layer prior to deposition of the cap layer 42. For example, the component can be exposed to an etchant such as HF before the carbon and / or boron cap layer 42 is deposited. This helps to minimize native oxide growth on the surface of the core layer 41.

[0079]

[0085] The features of the various embodiments described herein may be combined with each other, unless the features are clearly technically incompatible with each other. For example, a sacrificial layer comprising at least one of carbon, boron, and SiON may be partially removed in a loading bay and further removed in an exposure environment that may be additionally heated to reduce outgassing of silicon from the pellicle.

[0080]

[0086] In one embodiment, a method of making pellicle 80 includes depositing a layer of substrate. The substrate may form a majority of the frame 81 of the completed pellicle 80. The substrate may be etched away to expose the membrane 40 of the pellicle 80 while leaving a portion of the substrate to form the frame 81. A mask may be used to selectively etch away the substrate.

[0081]

[0087] Although specific reference is made herein to the use of lithographic apparatus in IC manufacturing, it should be understood that the lithographic apparatus described herein may have other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, LCDs, thin film magnetic heads, etc. The substrates described herein may be processed, before or after exposure, for example, in a track (a tool that typically applies a layer of resist to a substrate and develops the exposed resist), a metrology tool, and / or an inspection tool. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Additionally, a substrate may be processed multiple times, for example to create a multi-layer IC, and thus the term substrate as used herein may refer to a substrate that already includes multiple processing layers.

[0082]

[0088] Although specific embodiments of the present invention have been described above, the present invention allows for the replacement of various photoresist layers with non-photoresist layers that perform the same functions.

[0083]

[0089] The above description is intended to be illustrative rather than limiting. Thus, it will be apparent to one skilled in the art that modifications may be made to the invention as described without departing from the scope of the appended claims.

Claims

1. 1. A pellicle for EUV lithography, said pellicle comprising: a core layer comprising silicon and having at least one non-oxidized surface; a cap layer on at least one major surface of the core layer, the cap layer comprising carbon and / or boron.

2. The pellicle of claim 1 , wherein the cap layer has a thickness of 10 nm or less.

3. The pellicle of claim 1 or 2, wherein the core layer comprises crystals of a compound embedded in a matrix.

4. The pellicle of claim 3 , wherein the matrix comprises silicon.

5. The pellicle of claim 4 , wherein the matrix comprises SiN and / or elemental Si.

6. The pellicle according to any one of claims 3 to 5, wherein the compound contains molybdenum.

7. The compound is MoSi ２ and / or Mo ５ S ３ The pellicle of claim 6 , comprising:

8. The core is Si ｘ C ｙ The pellicle according to any one of claims 1 to 7, comprising:

9. The pellicle of any preceding claim, wherein the cap layer is a sacrificial layer that is removed to provide a bare core.

10. The cap layer is made of SiO ｘ , SiN ｙ and SiO ｘ N ｙ The pellicle according to any one of claims 1 to 9, comprising at least one from the group consisting of:

11. 1. An EUV lithography apparatus comprising: a low pressure environment for the EUV radiation beam path for the exposure operation; a pellicle disposed in the low pressure environment, the pellicle including a core layer including a compound including molybdenum embedded in a matrix including silicon, the core layer having at least one non-oxidized surface and exposed to a hydrogen plasma in the low pressure environment; An EUV lithography apparatus comprising:

12. The compound is MoSi ２ and / or Mo ５ S ３ 12. The EUV lithographic apparatus of claim 11 , comprising:

13. 13. An EUV lithographic apparatus according to claim 11 or 12, wherein the matrix comprises SiN and / or elemental Si.

14. An EUV lithographic apparatus according to any of claims 11 to 13, wherein the compound is formed as a crystal.

15. The core is Si ｘ C ｙ An EUV lithographic apparatus according to any of claims 11 to 14, comprising:

16. 1. An EUV lithography apparatus comprising: a low pressure environment for the EUV radiation beam path for the exposure operation; a loading bay for holding a pellicle to be introduced into the low pressure environment, the pellicle including a core layer comprising silicon and at least one cap layer comprising carbon and / or boron overlying the core layer; The loading bay includes an etcher configured to etch away the cap layer of a pellicle to expose the core layer.

17. 17. An EUV lithographic apparatus according to claim 16, wherein the etcher comprises a plasma source configured to provide a hydrogen plasma to etch the cap layer.

18. 18. An EUV lithographic apparatus according to claim 16 or 17, wherein the etcher comprises an ionising radiation source configured to ionise hydrogen gas in the loading bay to generate a hydrogen plasma.

19. 19. An EUV lithographic apparatus according to claim 18, wherein the ionizing radiation source is configured to provide microwave radiation to ionize hydrogen gas.

20. An EUV lithographic apparatus according to any of claims 16 to 19, wherein the etcher comprises an excitation radiation source configured to etch the cap layer.

21. 21. An EUV lithographic apparatus according to claim 20, wherein the excitation radiation source is configured to provide DUV radiation and / or EUV radiation.

22. The cap layer is made of SiO ｘ , SiN ｙ and SiO ｘ N ｙ 22. The EUV lithographic apparatus according to any of claims 16 to 21, comprising at least one from the group consisting of:

23. 1. An EUV lithography apparatus comprising: a low pressure environment for the EUV radiation beam path for the exposure operation; a pellicle disposed in the low pressure environment, the pellicle including a core layer comprising silicon and a cap layer on at least one major surface of the core layer comprising carbon and / or boron; a pellicle heater configured to maintain the pellicle at a temperature of at least 500° C.

24. 24. The EUV lithographic apparatus of claim 23, wherein the pellicle heater comprises a heating radiation source.

25. 25. An EUV lithographic apparatus according to claim 24, wherein the heating radiation source is configured to provide infrared radiation to heat the pellicle.

26. An EUV lithographic apparatus according to any of claims 23 to 25, wherein the pellicle heater comprises an ohmic heater configured to apply an electric current to the pellicle.

27. An EUV lithographic apparatus according to any of claims 23 to 26, wherein the pellicle heater comprises a thermionic heater configured to provide charged particles.

28. 1. A method for making a pellicle for EUV lithography, the method comprising: depositing a core layer comprising silicon and having at least one non-oxidized surface; and depositing a cap layer on at least one major surface of the core layer, the cap layer comprising carbon and / or boron.

29. 30. The method of claim 28, wherein the core layer is deposited in a vacuum and the cap layer is deposited while maintaining the vacuum.

30. 30. A method according to claim 28 or 29, comprising etching away any silicon oxide and / or silicon nitride formed on the surface of the deposited core layer prior to depositing the cap layer.

31. 1. A method for performing EUV lithography, the method comprising: projecting a beam of EUV radiation through a low pressure environment onto a substrate in an exposure operation; The method of claim 1, wherein the EUV radiation beam passes through a pellicle disposed in the low pressure environment, the pellicle including a core layer including a compound including molybdenum embedded in a matrix including silicon, the core layer having at least one non-oxidized surface, and the pellicle is exposed to a hydrogen plasma in the low pressure environment.

32. 1. A method for loading a pellicle into a low pressure environment of an EUV lithography apparatus, the method comprising: holding a pellicle in a loading bay for introduction into the low pressure environment, the pellicle including a core layer comprising silicon and at least one cap layer comprising carbon and / or boron overlying the core layer; Etching away the cap layer of the pellicle to expose the core layer; and moving the pellicle from the loading bay to the low pressure environment for an exposure operation.

33. 33. The method of claim 32, wherein the etching comprises providing a hydrogen plasma to etch the cap layer.

34. 34. The method of claim 32 or 33, wherein the etching comprises ionizing hydrogen gas in the loading bay to generate a hydrogen plasma.

35. The method of any of claims 32 to 34, wherein said etching comprises exciting said cap layer with excitation radiation to etch said cap layer.

36. 1. A method for performing EUV lithography, the method comprising: projecting a beam of EUV radiation onto a substrate through a low pressure environment in an exposure operation, the beam of EUV radiation passing through a pellicle disposed in the low pressure environment, the pellicle including a core layer comprising silicon and a cap layer comprising carbon and / or boron on at least one major surface of the core layer; and maintaining the pellicle at a temperature of at least 500°C.

37. 37. The method of claim 36, comprising maintaining the pellicle at a temperature of at least 700 degrees Celsius.

38. 38. The method of claim 36 or 37, wherein heating comprises providing heating radiation.

39. The method of any of claims 36 to 38, wherein the heating comprises passing an electric current through the pellicle.

40. The method of any of claims 36 to 39, wherein the heating comprises providing charged particles to thermionic heat the pellicle.

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