EUV reticle manufacturing

Abstract

A method of manufacturing an EUV reticle for an EUV exposure apparatus comprises providing a first substrate comprising a reflective layer configured to reflect EUV light and an absorbent layer configured to absorb the EUV light, exposing the first substrate to a patterned radiation beam and developing the exposed first substrate to form a patterned surface comprising the reflective layer and the absorbent layer. The first substrate is placed onto a reticle stage carrier to form the EUV reticle. The substrate may be a semiconductor substrate.

Description

EUV RETICLE MANUFACTURINGCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of US application 63 / 706,917 which was filed on 14 October 2024 and US application 63 / 876,703 which was filed on 5 September 2025, and which are incorporated herein in their entirety by reference.FIELD

[0002] The present invention relates to a method of manufacturing an EUV reticle for an EUV exposure apparatus, a method of exposing a target substrate, an EUV reticle manufactured by said method of manufacturing an EUV reticle for an EUV exposure apparatus and a reticle stage carrier for said EUV reticle.BACKGROUND

[0003] A lithographic apparatus is a machine constructed to apply a desired pattern onto a substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A lithographic apparatus may, for example, project a pattern at a patterning device (e.g., a mask) onto a layer of radiation-sensitive material (resist) provided on a substrate.

[0004] To project a pattern on a substrate a lithographic apparatus may use electromagnetic radiation. The wavelength of this radiation determines the minimum size of features which can be formed on the substrate. A lithographic apparatus, which uses extreme ultraviolet (EUV) radiation, having a wavelength within the range 4-20 nm, for example 6.7 nm or 13.5 nm, may be used to form smaller features on a substrate than a lithographic apparatus which uses, for example, radiation with a wavelength of 193 nm.

[0005] A development time of a patterning device is relatively long. On the one hand, extensive simulation and design verification of the pattern to be provided on patterning device may be required. On the other hand, the lead time associated with the manufacturing of the patterning device may be long and cost associated with the manufacturing of the patterning device may be high.SUMMARY

[0006] It is desirable to reduce a development time of a patterning device.

[0007] According to an aspect of the invention, there is provided a method of manufacturing an EUV reticle for an EUV exposure apparatus, comprising:- providing a first substrate comprising a reflective layer configured to reflect EUV light and an absorbent layer configured to absorb the EUV light;- exposing the first substrate to a patterned radiation beam;- developing the exposed first substrate to form a patterned surface comprising the reflective layer and the absorbent layer; and- placing the first substrate onto a reticle stage carrier to form the EUV reticle.

[0008] According to an aspect of the invention, there is provided a method of exposing a second target substrate, comprising:- manufacturing an prototyping EUV reticle according to the method of manufacturing an EUV reticle for an EUV exposure apparatus;- projecting, by an EUV-exposure apparatus, the prototyping EUV reticle onto the second target substrate.

[0009] According to an aspect of the invention, there is provided an EUV reticle manufactured by said method of manufacturing an EUV reticle for an EUV exposure apparatus.

[0010] According to an aspect of the invention, there is provided a reticle stage carrier for an EUV reticle, comprising:- a reticle stage carrier structure configured to fit on a reticle stage of an EUV exposure apparatus, the reticle stage carrier structure comprising an opening configured to hold an exposed substrate.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which:Figure 1 depicts a lithographic system comprising a lithographic apparatus and a radiation source;Figure 2A depicts substrates in which layers are arranged;Figure 2B depicts a patterning of the layers on the substrate;Figure 2C depicts a manufacturing of a patterning device from the patterned substrate;Figure 3 illustrates steps of manufacturing an EUV reticle according to another embodiment.DETAILED DESCRIPTION

[0012] Figure 1 shows a lithographic system comprising a radiation source SO and a lithographic apparatus LA. The radiation source SO is configured to generate an EUV radiation beam B and to supply the EUV radiation beam B to the lithographic apparatus LA. The lithographic apparatus LA comprises an illumination system IL, a support structure MT configured to support a patterning device MA (e.g., a mask), a projection system PS and a substrate table WT configured to support a substrate W.

[0013] The illumination system IL is configured to condition the EUV radiation beam B before the EUV radiation beam B is incident upon the patterning device MA. Thereto, the illumination system IL may include a facetted field mirror device 10 and a facetted pupil mirror device 11. The faceted field mirror device 10 and faceted pupil mirror device 11 together provide the EUV radiation beam B with adesired cross-sectional shape and a desired intensity distribution. The illumination system IL may include other mirrors or devices in addition to, or instead of, the faceted field mirror device 10 and faceted pupil mirror device 11.

[0014] After being thus conditioned, the EUV radiation beam B interacts with the patterning device MA. As a result of this interaction, a patterned EUV radiation beam B’ is generated. The projection system PS is configured to project the patterned EUV radiation beam B’ onto the substrate W. Forthat purpose, the projection system PS may comprise a plurality of mirrors 13,14 which are configured to project the patterned EUV radiation beam B’ onto the substrate W held by the substrate table WT. The projection system PS may apply a reduction factor to the patterned EUV radiation beam B’, thus forming an image with features that are smaller than corresponding features on the patterning device MA. For example, a reduction factor of 4 or 8 may be applied. Although the projection system PS is illustrated as having only two mirrors 13,14 in Figure 1, the projection system PS may include a different number of mirrors (e.g. six or eight mirrors).

[0015] The substrate W may include previously formed patterns. Where this is the case, the lithographic apparatus LA aligns the image, formed by the patterned EUV radiation beam B’, with a pattern previously formed on the substrate W.

[0016] A relative vacuum, i.e. a small amount of gas (e.g. hydrogen) at a pressure well below atmospheric pressure, may be provided in the radiation source SO, in the illumination system IL, and / or in the projection system PS.

[0017] The radiation source SO may be a laser produced plasma (LPP) source, a discharge produced plasma (DPP) source, a free electron laser (FEL) or any other radiation source that is capable of generating EUV radiation.

[0018] Figure 2A depicts a first substrate FW comprising a semiconductor material, such as a silicon substrate. The first substrate may be ultra flat, for example in that the top surface of the substrate has been flattened by a mechanical flattening operation. The first substrate may be a EUV reticle which is made using DUV reticle and DUV lithographic apparatus. The first substarte may be for example a target EUV reticle, a target substrate, a target EUV blank reticle, etc.

[0019] Two layers are consecutively provided on the substrate, namely a reflective layer RFL configured to reflect EUV light and an absorbent layer ABL configured to absorb the EUV light. In the present example, the reflective layer is arranged on top of the absorbent layer. In another example, the absorbent layer may be arranged on top of the reflective layer. A photoresist PHR is applied onto the reflective layer, i.e. the top layer of the reflective layer and the absorbent layer. In the alternative embodiment whereby the absorbent layer is arranged on top of the reflective layer, the photoresist is applied onto the absorbent layer.

[0020] Figure 2B depicts a following step, namely the exposing the substrate to a patterned radiation beam. The exposing the substrate to a patterned radiation beam may be performed in various ways, two examples being depicted in Figure 2B, indicted by A and B.

[0021] As a first example, the substrate is exposed by an electron beam, i.e. a so called E-beam, EB. A pattern PA may be written on the photoresist by the electron beam. As another example, the substrate is patterned by exposing the substrate to Deep Ultra Violet, DUV, radiation by a DUV exposure apparatus, such as a DUV lithographic apparatus. DUV-LA The pattern for patterning the DUV radiation may be provided by a DUV patterning device, DUV-MA. Due to an optical magnification factor of the DUV exposure apparatus, a scale of the DUV patterning device may be larger than a scale of the pattern projected by the DUV exposure apparatus onto the substrate. Thus, the DUV exposure apparatus may project the pattern from the DUV patterning device onto the substrate at a magnification factor of less than one, i.e. reducing the size of the pattern from the DUV patterning device to the pattern on the first substrate.

[0022] As depicted in Figure 2C, the patterned first substrate FS is processed by developing DEV the exposed photoresist, etching ETC of the top layer of the substrate (i.e. in the present example the reflective layer) in accordance with the patterned resist layer, and STR stripping of the remaining resist, etc. to provide an arrangement of the reflective layer and the absorbent layer in accordance with the pattern projected onto the substrate, namely the absorbent layer at the parts where the reflective layer has been etched away and the reflective layer at the parts where the reflective layer has not been etched away, i.e. where it was covered by the resist during the etching process.

[0023] The first substrate may then be cut CTR, in that the surrounding parts of the first substrate, i.e. parts outside the pattern of reflective and absorbent layers, may be removed. The substrate as thus obtained may be placed onto a reticle stage carrier to form a prototyping patterning device.

[0024] In the present document, the patterning device may also be identified as a reticle or a mask.

[0025] The described EUV reticle may enable to create a prototyping reticle to be used for exposure in an EUV exposure apparatus. The prototyping reticle may be used for design verification and evaluation of the pattern of the reticle. The prototyping reticle may be manufactured using equipment that is commonly used in semiconductor manufacturing processes, namely E-beam or DUV patterning, etching, etc. Thus, the prototyping reticle may be manufactured “in house” by a semiconductor manufacturer using equipment already available for semiconductor manufacturing.

[0026] Accordingly, an EUV reticle for an EUV exposure apparatus, such as a prototyping reticle, may be manufactured relatively fast and at relatively low cost when compared to the manufacturing of an EUV reticle, which may enable to verify a design of the pattern of the EUV reticle at a desired stage during a design process. A functionality of the pattern may be tested by on the EUV exposure apparatus using the prototyping reticle.

[0027] In an embodiment, the absorbent layer is arranged between a base of the first substrate and the reflective layer. The reflective layer may accordingly be arranged on top of the absorbent layer and the etching may be performed in the reflective layer to etch away selected parts of the reflective layer to expose the absorbent layer.

[0028] In an embodiment, a signal to noise ratio between the absorption layer and the reflection layer is two orders of magnitude or higher. The term order of magnitude may be understood as a factor 10. Thus, the term two orders of magnitude may be understood as a factor ten to the power of two, i.e. a factor 100. Although a contrast of a factor 100 may be relatively low when compared to a contrast of an EUV reticle, this relatively low contrast, i.e. relatively low signal to noise ratio, may be compensated by a longer exposure time at the EUV exposure apparatus. Thus, prototyping and design evaluation may be performed, even when making use of a pattern at the reticle that has a relatively low contrast between the reflective parts and the absorbing parts of the pattern. Alternatively, the multilayer has a reflectance in the range of 63-65% reflectance, and the binary absorber has for example about 2% reflectance. The material with low refractive index n may have a reflectance varying from 6% to 13% or higher than 13%.

[0029] In an embodiment, the exposing the first substrate to the patterned radiation beam is performed by an E-beam or a DUV radiation. Both technologies may be readily available at semiconductor manufacturing sites, hence the pattern may be provided on the prototyping reticle using equipment available at the semiconductor manufacturing site. A relatively high performance may be obtained for the prototyping EUV reticle pattern resolution, as the prototyping reticle is scaled according to a scaling factor of the EUX exposure apparatus. As the EUV exposure apparatus may commonly scale down in image size from the EUV reticle to the EUV pattern projected on the substrate, the EUV prototyping reticle may be larger in size compared to the target pattern on the substrate. Accordingly, the when using DUV radiation to project the pattern on the first substrate by a DUV exposure apparatus, the DUV reticle as may be required for such protection may be twice scaled, namely according to the scaling factor of the EUV exposure apparatus and according to the scaling factor of the DUV exposure apparatus which projects the DUV reticle on the first substrate. Due to this dual scaling, a size and scale of the DUV reticle may be substantially larger compared to the size and scale of the prototyping reticle. Therefore, a relatively common and relatively low cost DUV reticle may be used to manufacture the prototyping EUV reticle.

[0030] In an embodiment, the method further comprises cutting the substrate to a shape and size of the reticle stage carrier. A reticle stage carrier may provide for example alignment marks for alignment of the reticle and may carry the reticle. Cutting the first substrate to a shape and size of the reticle stage carrier may enable to make use of an existing reticle stage carrier, thus being able to use the prototyping reticle within a relatively short prototyping reticle manufacturing time.

[0031] In an embodiment, the first substrate is a semiconductor material substrate, such as a silicon substrate, thus being able to make use of existing substrates on which a reflective and an absorbent layer may be provided.

[0032] An example of a step by step process for fast prototyping is summarized in the below:

[0033] - Providing a reticle design.

[0034] - Writing the reticle pattern with an E-beam on the fast prototyping substrate, or- Manufacturing a mask for DUV scanner on the basis of the reticle design times the magnification of the exposing scanner, which may print the pattern on the fast prototyping substrate.

[0035] - Developing the fast prototyping substate (in wafer processing).

[0036] - Etching the fast prototyping substrate (in wafer processing) to obtain an EUV reticle pattern.

[0037] - Cutting the fast prototyping substrate to size.

[0038] - Mounting the fast prototyping substrate in the substrate carrier

[0039] - Loading the substrate carrier to reticle stage.

[0040] - Exposing a wafer, i.e. a substrate, with the fast prototyping substrate in an EUV-system. Since the reflectivity of the substrate is a lower than a standard EUV-reticle, the exposure time may be longer.

[0041] According to an aspect, there is provided a method of exposing a target substrate, comprising: manufacturing an EUV reticle according to the above described method of manufacturing an EUV reticle; and projecting, by an EUV-exposure apparatus, the EUV reticle onto the target substrate. The EUV reticle may hence be used for prototyping and evaluation, the pattern on the EUV reticle may be projected onto a target substrate using an EUV exposure apparatus. Based on an evaluation of the target substrate, e.g. the pattern as projected by the EUV exposure apparatus onto the target substrate using the EUV reticle, the performance of the pattern of the EUV reticle may be evaluated and adapted where desired. An engineering, design and testing cycle may accordingly be shortened and aspects of the design may be evaluated at an early stage using the EUV reticle.

[0042] In an embodiment, the method comprises adjusting an exposure time of the EUV-exposure apparatus in accordance with a reflectivity of the reflective layer of the EUV reticle. As described above, the reflectivity and / or the optical contrast between the reflective and absorbent layers may be lower than a regular EUV reticle. The lower reflectivity and / or contrast may at least partly be compensated by an adjustment of the exposure time. For example as the reflectively of the reflective layer of the (prototyping) EUV reticle may be low, the exposure time may be increased to compensate for a loss of EUV radiation at the target substrate.

[0043] According to an aspect, there is provided an EUV reticle manufactured by the method of manufacturing an EUV reticle.

[0044] According to an aspect, there is provided a reticle stage carrier for an EUV reticle, comprising a reticle stage carrier structure configured to fit on a reticle stage of an EUV exposure apparatus, the reticle stage carrier structure comprising an opening configured to hold an exposed substrate. The reticle stage carrier, as referred to above, may for example comprise an alignment mark and / or alignment sensor.

[0045] In an embodiment, the method comprises: - exposing a second substrate to a patterned radiation beam to form a master EUV reticle; - wherein the exposing the first substate to the patterned radiation beam comprises projecting, by the EUV exposure apparatus, the master EUV reticle onto the first substrate. Accordingly, a two step method is adhered to: a master EUV reticle is created by exposing the second substrate to a patterned radiation beam. The master EUV reticle is in the second step appliedto project the patten from the master EUV reticle onto the first substrate to create the EUV reticle. Due to this two step approach and the optical scaling factor of the EUV exposure apparatus, the pattern size of the master EUV reticle may be larger than the pattern size of the EUV reticle. The larger pattern size of the master EUV reticle may enable to perform the patterning of the master EUV reticle by a plurality of techniques, as further explained below.

[0046] Reverting to the scaling, in an embodiment, the EUV exposure apparatus is configured to project the EUV reticle onto a target substrate, wherein the EUV reticle is scaled relative to the target substrate according to a scaling factor and wherein the master EUV reticle is scaled according to a square of the scaling factor. For example, in case a scaling of the EUV exposure apparatus would for example be 4, i.e. the pattern on the EUV reticle being 4 times larger than the pattern as projected by the EUV exposure apparatus onto the target substrate, then, using the same or similar EUV exposure apparatus, the pattern on the master EUV reticle may be 4 times larger than the pattern on the EUV reticle, thus 16 times larger than the pattern on the target substrate. This quadratic increase in scale may facilitate the patterning of the master EUV reticle.

[0047] In an embodiment, the master EUV reticle comprises a part of a pattern of the EUV reticle, and wherein the master EUV reticle is projected by the EUV exposure apparatus onto the first substrate plural times, using a stitching process. The pattern on the EUV reticle may contain a repetitive part, such as memory parts or data processing core parts. The master EUV reticle comprising the repetitive part may be projected onto the first substrate repetitively using the stitching process.

[0048] In an embodiment, the EUV reticle is further formed by an E-beam mask writer and wherein the EUV exposure apparatus and the E-beam mask writer are used sequentially. The E-beam mask writer may for example be used to complement the repetitive pattern projected by the EUV exposure apparatus, in order to project for example remaining, e.g. a non-repeatable part of the pattern.

[0049] Optical proximity correction may be applied at a high resolution. For example, the E-beam mask writer ma be used to write a high resolution optical proximity correction pattern part on the first substrate.

[0050] In an embodiment, as an exposure dose of the EUV exposure apparatus and the E-beam writer may be in a same order of magnitude, a same photoresist on the first substrate may be exposed by the EUV exposure apparatus and the E-beam mask writer.

[0051] Alignment marks and overlay marks may be available. In an embodiment, the alignment marks and overlay marks are used in the stitching process and a combination process using the EUV exposure apparatus and the E-beam mask writer so as to provide that parts of the pattern as projected by the EUV exposure apparatus and the parts of the pattern as projected by the E-beam mask writer may be aligned, for example, the repetitive parts of the pattern and the remaining parts of the pattern to be aligned.

[0052] For example, having projected the repetitive parts of the pattern by the EUV exposure apparatus using the master EUV reticle, the alignment marks may be read by an alignment mark reader of the e- beam writer.

[0053] A two step optical proximity correction may be performed. Alternatively, a direct optical proximity correction according to the square of the scaling factor of the exposure apparatus may be performed.

[0054] An optimization process may be performed, in that a design pattern as is to be projected on the target substrate, i.e. a design pattern of the EUV reticle, is categorized into a repeating design pattern and non-repeating design pattern. The pattern of the master EUV reticle may then be defined a according to the repeating design pattern.

[0055] An example of the above two step approach to create an EUV reticle will be explained below with reference to Figure 3. Seen from the right side to the left side, figure 3 depicts the writing of a pattern MPT for a master EUV reticle onto a second substrate SW. The writing of the master EUV reticle may be performed by, for example, an electron beam, E-beam, writer, such as a multi beam writer MEB configured to write multiple electron beams simultaneously. The master EUV reticle is formed from the thus patterned second substrate, e.g. using the techniques of the reflective and absorbent layer as described with reference to Figures 2A - 2C. The electron beam writing technology may be applied for the second substrate, as the scale of the master EUV reticle MMA to be provided may according to a square of the scaling factor of the EUV exposure apparatus, as a result of the dual step approach to follow. In the present example as depicted in Figure 3, the square of the scaling factor provides a magnification by a factor 16 compared to the pattern on the target substrate.

[0056] The master EUV reticle is projected onto the first substrate by an EUV exposure apparatus EUV-LA, bringing the scale at the first substrate, in the present example, from 16 in accordance with the square of the scaling factor, to 4 in accordance with the scaling factor of the EUV exposure apparatus. The EUV reticle MA may be produced on the basis of the patterned first substrate. The EUV exposure apparatus EUV-LA may project the EUV reticle onto the target substrate W to pattern the target substrate W.

[0057] A trend is semiconductor industry is towards increase of the photomask (i.e. reticle) size from , e.g. from [6 inch x 6 inch] to [6 inch x 11.2(or between 11.2 and 12) inch]. In a prior art photomask patterning process, e-beam direct writing may be a typical technology and its writing time may get longer as the device design rule may shrink with a complex Optical Proximity Correction, OPC, and a higher pattern quality may be required.

[0058] Tighter design rule may increase the pattern density and may require more electrons to reduce an e-beam shot noise. In addition, a curvilinear design application may increase the data volume and a data transfer time. These factors may increase the total writing time of the e-beam writing technology, although the industry developed the Multi-Beam Mask Writer, MBMW. The typical writing time of a [6 inch x 6 inch] mask may be long, e.g. 12 ~ 24 hours for a high end EUV mask. Thus, in case the reticle size would be increased, the writing time of [6 inch x 11 ,2(or between 11.2 and 12) inch] would be 24 ~ 48 hours(0.5 ~ 1 mask / day) using the current MBMW system.

[0059] Moreover, the prior art e-beam technology may increase a pattern placement error by the slipping drift of the blank mask and charging effect during the long writing time, may increase the risk of the cathode discharge during the long writing time, may increase e-beam writing tool investment for the productivity of the mask and may increase the mask fabrication cost and the final device price.

[0060] Further, electron density of e-beam technology may be small comparing to photon density of EUV technology. This may imply that e-beam lithography may also have a stochastic noise issue and may require to increase the exposure energy to improve the pattern quality. Moreover, the photomask industry is using larger than 150uC / cm2 dose with MB MW, and this makes the e-beam writing speed slow again.

[0061] In addition, future Optical Proximity Correction designs may increase a data volume, a data transfer rate during pattern writing may form a bottleneck of a throughput.

[0062] In view of the above described problems associated with the prior art, the present two step method may be employed for the large size mask format, may reduce the patterning process time, may increase a mask production capability and may enhance a productivity. EUV technology has less stochastic noise, no necessity of data transfer, and no electron charging effect.

[0063] It is proposed to use the EUV scanner, i.e. the EUV exposure apparatus for the reticle manufacturing and / or the double size reticle fabrication.

[0064] The EUV process may have the below advantages compared to the prior art e-beam process: a high throughput, an absence of charging effect, hence no need of charging effect correction a high resolution.

[0065] As EUV scanner may be faster than e-beam MBMW, a higher dose application may be acceptable to remove the stochastic noise and to provide a high pattern quality.

[0066] EUV mask scanner needs the Master EUV reticle (6-inch : 16x scale) to transfer the images on the double size EUV blank mask (4x scale). With the stow step method, on the basis of an optical scaling of a factor 4, the Master EUV reticle scale must be 16x. For example, 8nm pattern on wafer will be 32nm on the large size mask and 128nm on the Master EUV reticle. In order to make the full field mask on the double size blank mask, multiple exposure may be applied.

[0067] And the stitching process is required across multiple shots of the Master EUV reticles. Since the application of many Master EUV reticles may increase the mask cost, the categorization of the repeating designs may be desired to reduce the number of Master EUV reticles and the production cost.

[0068] The EUV mask scanner may be used not only for double size mask fabrication but also for conventional mask fabrication if the bottom stage is designed to load both size blank masks.

[0069] The EUV mask fabrication process may include the E-beam writing technology which makes the non-repeating pattern designs and / or additional OPC patterns. The process sequence may be EUV scanner first and E-beam writer second, or vice versa, (photo-etch-photo-etch process).

[0070] Since EUV and E-beam energy levels may be similar, a single photoresist may be made as EUV photoresist and E-beam photoresist. The photoresist optimization may be possible for the resistpaterning using two energy source - EUV and E-beam. In this case, photo-photo-etch process is possible.

[0071] For example, an EUV lithographic apparatus may use a 16x scale master mask to make 4x photomask for wafer process. The EUV lithographic apparatus may have a stage which can load 6 x 6 x 0.25 inch standard blank mask and / or 6 x 11.2 x 0.25 inch double size blank mask within 5% dimension tolerance. The stage design may also be different with respect to the blank mask dimensions such as 6 x 11.3 x 0.25 inch, 6 x 12 x 0.25 inch, 6 x 12 x 0.4 inch, or alike. In an example, the mask paterning process may use sequentially an EUV lithographic apparatus and an e-beam mask writer. The additional e-beam writing process may be used for a non-repeatable patern design. The additional e-beam writing process may be used for a high resolution OPC design. In an example, the reticle alignment marks and overlay marks may be used for a stitching process wherein witing using EUV lithographic apparatus and an E-beam writer are combined. The e-beam writer may be sued to read the reticle alignment marks. The e-beam writer may have an optical alignment mark reader. Using a two step OPC solution or a direct OPC solution may be advantageous to make the 16x master mask layout from the lx device design. An algorithm may be used to categorize any repeating design and nonrepeating design from the full chip design. The photoresist layer for manufacturing semiconductor devices may be exposed by both of EUV radiation and E-beam.

[0072] Although specific reference may be made in this text to the use of lithographic apparatus in the manufacture of ICs, it should be understood that the lithographic apparatus described herein may have other applications. Possible other applications include the manufacture of integrated optical systems, guidance and detection paterns for magnetic domain memories, flat-panel displays, liquid-crystal displays (LCDs), thin-film magnetic heads, etc.

[0073] Although specific reference may be made in this text to embodiments of the invention in the context of a lithographic apparatus, embodiments of the invention may be used in other apparatus. Embodiments of the invention may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus that measures or processes an object such as a wafer (or other substrate) or mask (or other paterning device). These apparatus may be generally referred to as lithographic tools. Such a lithographic tool may use vacuum conditions or ambient (non-vacuum) conditions.

[0074] Although specific reference may have been made above to the use of embodiments of the invention in the context of optical lithography, it will be appreciated that the invention, where the context allows, is not limited to optical lithography and may be used in other applications, for example imprint lithography.

[0075] Where the context allows, embodiments of the invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the invention may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmiting information in a form readable by a machine (e.g., a computing device). For example, amachine-readable medium may include read only memory (ROM); random access memory (RAM); magnetic storage media; optical storage media; flash memory devices; electrical, optical, acoustical or other forms of propagated signals (e.g. carrier waves, infrared signals, digital signals, etc.), and others. Further, firmware, software, routines, instructions may be described herein as performing certain actions. However, it should be appreciated that such descriptions are merely for convenience and that such actions in fact result from computing devices, processors, controllers, or other devices executing the firmware, software, routines, instructions, etc. and in doing that may cause actuators or other devices to interact with the physical world.

[0076] While specific embodiments of the invention have been described above, it will be appreciated that the invention may be practiced otherwise than as described. The descriptions above are intended to be illustrative, not 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 claims set out below.

Claims

CLAIMS1. A method of manufacturing an EUV reticle for an EUV exposure apparatus, comprising:- providing a first substrate comprising a reflective layer configured to reflect EUV light and an absorbent layer configured to absorb the EUV light;- exposing the first substrate to a patterned radiation beam;- developing the exposed first substrate to form a patterned surface comprising the reflective layer and the absorbent layer; and- placing the first substrate onto a reticle stage carrier to form the EUV reticle.

2. The method according to claim 1, wherein the absorbent layer is arranged between a base of the first substrate and the reflective layer.

3. The method according to claim 1 or 2, wherein a signal to noise ratio between the absorption layer and the reflection layer is two orders of magnitude or higher.

4. The method according to any one of the preceding claims, wherein the exposing the first substrate to the patterned radiation beam is performed by an E-beam, EUV or a DUV radiation.

5. The method according to any one of the preceding claims, further comprising cutting the first substrate to a shape and size of the reticle stage carrier.

6. The method according to any one of the preceding claims, wherein the first substrate is a semiconductor material substrate, such as a silicon substrate.

7. A method of exposing a target substrate, comprising:- manufacturing an EUV reticle according to the method of any one of the preceding claims;- projecting, by an EUV-exposure apparatus, the EUV reticle onto the target substrate.

8. The method according to claim 7, comprising:- adjusting an exposure time of the EUV-exposure apparatus in accordance with a reflectivity of the reflective layer of the EUV reticle.

9. An EUV reticle manufactured by the method according to any one of claims 1 - 6.

10. A reticle stage carrier for a prototyping reticle, comprising:- a reticle stage carrier structure configured to fit on a reticle stage of an EUV exposure apparatus, the reticle stage carrier structure comprising an opening configured to hold an exposed first substrate.

11. The method according to any one of claims 1 - 6, comprising:- exposing a second substrate to a patterned radiation beam to form a master EUV reticle;- wherein the exposing the first substate to the patterned radiation beam comprises projecting, by the EUV exposure apparatus, the master EUV reticle onto the first substrate.

12. The method according to claim 11, wherein the EUV exposure apparatus is configured to project the master EUV reticle onto a target EUV substrate having a 4x magnification, wherein the target EUV reticle is scaled relative to the device design rule on the Si wafer substrate according to a scaling factor and wherein the master EUV reticle is scaled according to a square of the scaling factor.

13. The method according to claim 11 or 12, wherein the master EUV reticle comprises a part of a pattern of the EUV reticle, and wherein the master EUV reticle is projected by the EUV exposure apparatus onto the target EUV reticle substrate plural times, using a stitching process.

14. The method according to any one of claims 11 - 13, wherein the target EUV reticle is further formed by an E-beam mask writer and wherein the EUV exposure apparatus and the E-beam mask writer are used sequentially.

15. The method according to claim 14, wherein the E-beam mask writer is used to write a nonrepeatable pattern part on the target EUV reticle substrate.

16. The method according to claim 14 or 15, wherein the E-beam mask writer is used to write a high resolution optical proximity correction pattern part on the target EUV reticle substrate.

17. The method according to any one of claims 14 - 16, comprising exposing a same photoresist on the first substrate by the EUV exposure apparatus and the E-beam mask writer.

18. The method according to any one of claims 14 - 17, wherein alignment marks and overlay marks are used in the stitching process and a combination process using the EUV exposure apparatus and the E-beam mask writer.

19. The method according to claim 18 , wherein the alignment marks are read by an alignment mark reader of the e-beam writer.

20. The method according to any one of claims 11 - 19, comprising performing a two-step optical proximity correction or a direct optical proximity correction according to the square of the scaling factor of the exposure apparatus.

21. The method according to any one of claims 11 - 20, comprising categorizing a design pattern of the EUV reticle into a repeating design pattern and non-repeating design pattern and defining a pattern of the master EUV reticle according to the repeating design pattern.

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