Patterning device

Abstract

A patterning device configured for use in a lithographic apparatus configured to image a pattern of the patterning device onto a substrate via projection optics using radiation. The patterning device comprises: a first component configured to reflect and / or transmit the radiation; and a second component covering at least a portion of a surface of the first component and configured to at least partially absorb the radiation incident on the second component. The second component comprises a sidewall, wherein at least a portion of the sidewall extends away from the first component at an angle relative to a plane parallel to the surface of the first component, and wherein the angle is less than 85 degrees.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to EP application 19172160.4, filed on May 2, 2019, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to a pattern forming device. Background Art

[0004] A lithographic apparatus is a machine configured to apply a desired pattern to a substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). For example, a lithographic apparatus can project a pattern from a patterning device (e.g., a mask) onto a layer of radiation-sensitive material (resist) disposed on a substrate.

[0005] To project a pattern onto a substrate, a lithographic apparatus can use electromagnetic radiation. The wavelength of this radiation determines the minimum size of features that can be formed on the substrate. Compared to lithographic apparatuses that use radiation with a wavelength of, for example, 193 nm, lithographic apparatuses that use extreme ultraviolet (EUV) radiation with a wavelength in the range of 4 to 20 nm (e.g., 6.7 nm or 13.5 nm) can be used to form smaller features on a substrate.

[0006] Using a standard attenuated phase-shift patterning device in a lithographic apparatus may result in only a relatively small percentage of the radiation intensity being diffracted into diffraction orders within the numerical aperture (NA) of the lithographic apparatus. Due to this, a relatively high percentage of the radiation is lost, and this increases the desired dose. Therefore, it may be desirable to increase the percentage of radiation intensity that is diffracted into diffraction orders within the NA of the lithographic apparatus. Summary of the Invention

[0007] According to a first aspect of the present invention, there is provided a pattern forming device configured for a lithographic device, the lithographic device being configured to image a pattern at the pattern forming device onto a substrate via projection optical devices using radiation, the pattern forming device comprising: a first component for reflecting and / or transmitting radiation; and a second component covering at least a portion of a surface of the first component and being configured to at least partially absorb radiation incident on the second component, wherein the second component comprises a side wall, wherein at least a portion of the side wall extends away from the first component at an angle relative to a plane parallel to the surface of the first component, and wherein the angle is less than 85 degrees.

[0008] This can have the following advantages: more radiation can be diffracted into the numerical aperture (NA) of the lithographic apparatus, which can reduce the required radiation dose. The shape of the second element can reduce the intensity of radiation diffracted to higher orders compared to the intensity of radiation diffracted by a standard patterning device (where the sidewalls are perpendicular to the corresponding first element). This can improve the output of the lithographic apparatus.

[0009] The second component may at least partially transmit radiation incident on the second component thereby imparting a phase shift to radiation emitted from the second component relative to radiation reflected from another part of the first component not covered by the second component.The patterning device may be an attenuated phase shifting patterning device.

[0010] At least the portion of the side wall may be a substantial portion of the side wall.

[0011] The at least portion may be a majority of the side wall.

[0012] The sidewall may extend from the first component at an angle away from the first portion at approximately a midpoint of the sidewall.

[0013] The side wall may be angled at a substantially furthest point of the side wall away from the first component.

[0014] At a substantially furthest point of the side wall from the first component, the side wall may have a curved shape.

[0015] The curve may be a sinusoidal curve. This may have the advantage of providing an increased amount of radiation diffracted into the system NA when compared to other curves.

[0016] The side wall may extend from the first component away from the first portion at an angle across the side wall.

[0017] The angle may be less than 70 degrees.

[0018] The angle may be 45 degrees.

[0019] The second component may have a further sidewall generally opposite the sidewall of the second component, wherein at least a further portion of the further sidewall may extend from the first component at an angle away from the first portion.

[0020] The angle at which the further sidewall extends from the first component may be different from the angle at which the sidewall extends from the first component.

[0021] The second component may have one or more additional side walls, wherein at least one additional portion of the one or more additional side walls may extend from the first component at an angle away from the first portion.

[0022] The angle at which the one or more additional side walls may extend from the first component may be different from the angle at which the side walls extend from the first component.

[0023] The patterning device may be at least one of a reflective patterning device, a transmissive patterning device, a binary patterning device, and an attenuated phase-shift patterning device. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which:

[0025] - Figure 1 A lithographic system including a lithographic apparatus and a radiation source is depicted;

[0026] - Figure 2a depicts a schematic diagram of a cross-sectional side view of an attenuated phase-shift patterning device according to an embodiment of the present invention;

[0027] - Figure 2b Describes the basis Figure 2a Schematic diagram of a top view of an attenuated phase-shift patterning device of an embodiment;

[0028] - Figure 3 depicts a schematic diagram of a cross-sectional side view of an attenuated phase-shift patterning device according to another embodiment of the present invention;

[0029] - Figure 4a A schematic diagram depicting a cross-sectional side view of a standard patterning device;

[0030] - Figure 4b A schematic diagram depicting a cross-sectional side view of an attenuated phase-shift patterning device according to another embodiment of the present invention is depicted. DETAILED DESCRIPTION

[0031] Figure 1 A lithographic system is shown 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.

[0032] The illumination system IL is configured to condition the EUV radiation beam B before it is incident on the patterning device MA. The illumination system IL may include a faceted field mirror arrangement 10 and a faceted pupil mirror arrangement 11. The faceted field mirror arrangement 10 and the faceted pupil mirror arrangement 11 together provide the EUV radiation beam B with a desired 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 arrangement 10 and the faceted pupil mirror arrangement 11.

[0033] After being so 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. For this purpose, the projection system PS may comprise a plurality of mirrors 13, 14 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′ so as to form an image in which features 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 being Figure 1 While there are only two mirrors 13, 14 in the projection system PS, the projection system PS may comprise a different number of mirrors (eg six or eight mirrors).

[0034] The substrate W may include a previously formed pattern. In this case, the lithographic apparatus LA aligns the image formed by the patterned EUV radiation beam B' with the pattern previously formed on the substrate W.

[0035] A relative vacuum, ie, a small amount of gas (eg, hydrogen) at a pressure well below atmospheric pressure, may be provided in radiation source SO, illumination system IL, and / or projection system PS.

[0036] 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 capable of generating EUV radiation.

[0037] Figure 2a A close-up side view of a portion of a patterning device MA is shown, which in this embodiment is an attenuated phase-shifting patterning device. More specifically, Figure 2a Shown by Figure 2b A cross-sectional side view of the attenuated phase shift pattern forming device MA taken along line AA′. Figure 2b It is to be understood that for the sake of clarity, Figure 2a and 2b Only parts of the attenuated phase-shift patterning device MA are shown.

[0038] Phase-shifting patterning devices are photomasks that use interference generated by phase differences to improve image resolution in photolithography. Phase-shifting patterning devices rely on the fact that radiation passing through (i.e., in this case, reflected from) a transparent medium will undergo a phase change as a function of its optical thickness.

[0039] The attenuated phase shift patterning device MA comprises a first component 22 for reflecting radiation and a second component 24 for reflecting radiation having a different phase relative to the radiation reflected from the first component. The first component 22 comprises a standard multilayer mirror, for example alternating layers of molybdenum and silicon. For simplicity, the layers of the multilayer are not shown in FIG. Figure 2a It will be appreciated that in other embodiments, the first component may have a different number of layers and / or may comprise different materials.

[0040] While embodiments have been described involving attenuated phase-shift patterning devices, it will be appreciated that these embodiments are exemplary and that the invention described is also applicable to other types of patterning devices. For example, other patterning devices known as "binary masks" may be used. The name "binary" derives from an idealized image where either all radiation is absorbed (0) or no light is absorbed (1) across the mask. Patterning devices for EUV radiation may use tantalum as the base material.

[0041] The second component 24 is in a different layer from the first component 22 , ie, the second component 24 is located on the first component 22 .

[0042] The second component 24 reflects a relatively small amount of radiation when compared to the first component 22. The radiation reflected from the second component 24 is not strong enough to create a pattern on the substrate W, but it may interfere with the radiation from the first component 22 in order to increase the contrast on the substrate W. Contrast can be thought of as the steepness or sharpness of features formed in the image on the substrate W.

[0043] from Figure 2a and Figure 2bAs can be seen in the figure, the second component 24 covers a portion of the first component 22 (hereinafter referred to as the covered portion 22b) except for the patterned uncovered portion 22a of the surface of the first component 22. Radiation reflected from the uncovered portion 22a generates a patterned radiation beam B', which, when in use, forms a pattern in a target portion of a substrate W in the lithographic apparatus LA. The covered portion 22b and the uncovered portion 22a together form the surface 23 of the first component 22. The second component 24 can be considered to surround the uncovered portion 22a of the first component 22, although the second component 24 is in a different layer than the first component 22 and is therefore effectively the covered portion 22b surrounding the uncovered portion 22a of the first component 22. The second component 24 can be considered to form a ring around the uncovered portion 22a of the first component 22. Although the area of ​​the uncovered portion 22a of the first component 22 can be generally square or rectangular when viewed from above, in other embodiments, the uncovered portion can be of any suitable shape, and the second component can have a corresponding size and shape. The size of the uncovered portion 22a is related to the critical dimension (CD) of the feature to be printed on the substrate W. On the patterning device MA, the size of the uncovered portion 22a is the CD (on the substrate W) multiplied by the magnification factor in the lithographic apparatus LA. This may have a range of + / - 30% (patterning device bias range). The magnification factor may be 4 to 8.

[0044] The second component 24 covers the covered portion 22b of the first component 22, which extends a distance d from the uncovered portion 22a of the first component 22. The optimal width will be feature and pitch dependent.

[0045] The second component 24 covers at least a portion of the surface of the first component 22 (the covered portion 22b) and is configured to at least partially absorb radiation incident on the second component 24 and at least partially transmit radiation incident on the second component 24, thereby giving a phase shift to the radiation emitted from the second component 24 relative to the radiation reflected from another portion of the first component 22 (the uncovered portion 22a) not covered by the second component 24. The width d of the second component 24 corresponds to the extent of the direction of the covered portion 22b of the first component 22 (taken parallel to the surface of the first component 22). The width d is Figure 2a and 2b Depicted as a double arrow.

[0046] Although Figure 2a and 2b Only a single uncovered portion 22a is shown in the Figures (because these figures only show part of the attenuated phase-shift patterning device MA), it being understood that the pattern may be formed by a plurality of uncovered portions 22a.

[0047] The terms cover, covered, and covering as used herein are intended to indicate that a covering component is in a position or situation such that radiation is at least partially blocked from being incident on a portion of the covered component that is below the covering component. In other words, covering may be considered to encompass covering where the covering component is in direct contact with the covered component or not, i.e., another component may or may not be located between the covered component and the covered component.

[0048] In this embodiment, the second component 24 comprises a material ruthenium (Ru) having a thickness t (shown as a double arrow in FIG2 ). Preferably, the thickness of Ru may be 35 nm. The material Ru of the second component 24 may be considered to have replaced an absorber material, such as a TaBN absorber, in a standard pattern forming device to form an attenuated phase shift pattern forming device MA. As will be appreciated, in other embodiments, different materials may be used instead of Ru. The thickness of the second component depends on the material composition, for example, an alloy material containing Ru may require a different thickness than an alloy material containing only Ru. Typical thicknesses of the absorber may range between 30 nm and 70 nm.

[0049] The attenuated phase-shift patterning device MA can be used in a lithographic apparatus LA by reflecting radiation from a first component 22 of the attenuated phase-shift patterning device MA and reflecting radiation from a second component 24 of the attenuated phase-shift patterning device MA. More specifically, radiation from a pattern comprising uncovered portions 22a of the first component 22 is reflected, and a patterned radiation beam B′ is generated. This has the effect that the radiation reflected from the second component 24 has a different phase relative to the radiation reflected from the first component 22, and provides a pattern with increased contrast on the substrate W.

[0050] The second feature 24 has sidewalls 26a, 26b that are angled relative to the first feature 22. That is, they do not extend completely perpendicular to the surface 23 of the first feature 22, as in a standard patterning device. The dimension of the second feature 24 in the direction of the intercept distance d decreases as the distance (thickness t) from the first feature 22 increases. The second feature 24 can be considered to have a rounded corner or curve at the approximately furthest point of the sidewalls 26a, 26b from the first feature 22. In some embodiments, the sidewalls can be completely curved (i.e., without straight sections), or one or more other portions of the sidewalls can be curved.

[0051] have Figure 2aThe illustrated shape of the second element 24 (i.e., a more rounded shape compared to a standard patterning device having straight sidewalls) limits the amount of radiation that is diffracted into higher orders. The Fourier transform of this more rounded shape will contain significantly fewer high-frequency components. Consequently, more radiation will be diffracted into the NA of the lithographic apparatus LA, which will reduce the required radiation dose. The shape of the second element 24 will reduce the intensity of radiation that is diffracted into higher orders compared to the intensity of radiation diffracted by a standard patterning device (with sidewalls perpendicular to the corresponding first element).

[0052] This will increase the throughput of the lithographic apparatus LA (i.e., the number of substrates W that pass through the lithographic apparatus LA at a particular time) compared to a standard patterning device having a second component made of Ru and having straight sidewalls extending perpendicular to the first component. Furthermore, the patterning device MA having the second component 24 will increase the throughput and yield (i.e., the number of defect-free substrates) compared to a standard patterning device having a second component made of Ta (with straight sidewalls). This is because with more radiation, features can be printed with better quality in the resist on the substrate W.

[0053] Table 1 below compares the photon losses of a standard 60nm (thickness) Ta-based mask and a 35nm (thickness) Ru-based attenuated phase-shift mask (PSM). The Ru mask has a lower extinction coefficient and thinner layers. Therefore, less radiation is lost during the two passes through the mask absorber. The examples here are given for dense contact holes (CH) with a 20% mask bias, so that 72% of the mask area is covered by the absorber material.

[0054] Additionally, most of the radiation is lost because only the 0th and 1st orders are within the NA (numerical aperture) of the system. The second column of Table 1 shows the fraction of the radiation intensity that is distributed among diffraction orders outside the NA. This is greater for the Ru mask than for the Ta mask (more radiation goes to higher orders). 80% of the radiation goes to diffraction orders outside the NA of the Ru mask, so if all the radiation were diffracted within the NA, the gain would be as much as 5 times. This is more than for the Ta mask, where 70% of the radiation goes to diffraction orders outside the NA.

[0055] Table 1: Comparison of photon losses for 20nm dense CH on low-NA EUV, standard 60nm Ta-based mask and 35-nm Ru-based attenuated PSM.

[0056]

[0057] The amount of radiation diffracted as -1 order (and possibly outside the NA for off-axis illumination) can never be significantly lower than the amount of radiation diffracted as +1 order, so it is theoretically impossible to reduce the amount of radiation radiated as diffraction orders outside the NA to zero. In a rough upper limit, the amount of radiation in +1, 0 and -1 will be equal, so 33% of the radiation will be discarded. In a scenario with a standard Ru mask, only 20% of the radiation is used (i.e. captured in the NA), while using a patterning device MA with the shape of the second component 24 means that 67% of the radiation is potentially available for use. This means that the upper limit will give a dose gain of about 3 times (i.e. the 67% of radiation available for use is about 3x20% of what was previously used). More generally, the patterning device MA provides a significant dose gain relative to a standard patterning device with a second component made of Ru.

[0058] It will be appreciated that the described shape of the second component 24 of the patterning device MA can also be used with patterning devices having a second component made of materials other than Ru. For example, these can be second components made of tantalum or other absorbers such as high-k absorbers, e.g., nickel or cobalt, as well as other attenuated phase-shift patterning device materials such as rhodium.

[0059] The shape of the second component 24 can be formed by isotropic plasma etching (higher pressure), depositing layers on top of discrete blocks of conventionally manufactured absorber material with sharp edges (the sharpness will disappear as additional layers are deposited on top), etching away material between the sinusoidal blocks and / or ion gunning.

[0060] Figure 3 A cross-sectional side view of an embodiment of a portion of patterning device 30 is shown. Figure 3 The portion of patterning device 30 shown corresponds only to Figure 2a Thus, only portions of the first component 32 and the second component 34 of the patterning device 30 are shown. It will be appreciated that the structure of the portion of the second component 34 shown may be the same or different for other portions of the second component 34.

[0061] The second member 34 (made of Ru) has side walls 36a, 36b that are aligned with the Figure 2a 32. That is, they do not extend completely perpendicular to the surface 33 of the first component 32 as in a standard patterning device. Similarly, the dimension of the second component 34 in the direction of the intercept distance d decreases as the distance (thickness t) from the first component 32 increases. The second component 34 can be considered to have a rounded corner or curve at or near the approximately farthest point of the sidewalls 36a, 36b from the first component 22. Figure 3In the second part 34, these rounded corners or curves are Figure 2a The second part 24 is more obvious because Figure 2a Like the second part 24, there is no flat surface between the curves. Figure 3 The second feature 34 peaks at the point where the side walls 36a, 36b meet. It is important that there are no sharp edges (such as 90 degree angles) that could cause unwanted diffraction.

[0062] With respect to a standard patterning device having a second component made of Ru, the patterning device 30 is also Figure 2a Dosage gain is provided in a similar manner as described.

[0063] In some embodiments, the curve of the sidewall at or near its substantially furthest point from the first component may be a sinusoidal curve. This may provide an increased amount of radiation diffracted into the NA of the system compared to other curves.

[0064] Figure 4a A cross-sectional side view of a portion of a standard patterning device 40 is shown for comparison. The standard patterning device 40 has a first component 42 and a second component 44 (made of Ru), wherein straight sidewalls 46a, 46b extend substantially perpendicularly relative to the first component 42 along the entire thickness t of the second component 44. In other words, the sidewalls 46a, 46b extend from the first component at 90 degrees to a plane parallel to the surface 43 of the first component 42 on all sidewalls 46a, 46b.

[0065] Figure 4b A cross-sectional side view of an embodiment of a portion of a patterning device 50 is shown. The patterning device 50 has a first component 52 and a second component 54 (made of Ru) having sidewalls 56a, 56b. For clarity, only sidewall 56a will be mentioned, but it will be understood that these features also apply to sidewall 56b or other sidewalls of the second component 54. In the patterning device 50, the sidewall 56a is straight, but is arranged in a manner similar to that of the sidewall 56b. Figure 2a 5. That is, sidewall 56a does not extend completely perpendicular to surface 53 of first feature 52 as in a standard patterning device. Similarly, the dimension of second feature 54 in the direction in which distance d is taken decreases with increasing distance (thickness t) from first feature 52.

[0066] More specifically, the sidewall 56a of the second component 54 extends away from the first portion from the first component 52 at an angle α relative to the surface 53 of the first component 52, and the angle α is less than 70 degrees. Angles greater than 70 degrees can provide relatively small yield gains. In this embodiment, the sidewall 56a extends away from the first portion from the first component 52 at an angle α relative to a plane P that is parallel to the surface 53 of the first component 52, and the plane P is located at a substantially midpoint of the sidewall 56a. It is understood that the plane P can be intercepted at any point along the sidewall 56a, and as shown from Figure 4b As can be seen in FIG, sidewall 56a extends away from the first portion from first component 52 at an angle α throughout sidewall 56a. That is, sidewall 56a maintains the same angle α relative to a plane parallel to surface 53 of first component 52 along the entire length of sidewall 56a.

[0067] With respect to a standard patterning device having a second component made of Ru, the patterning device 50 is also Figure 2a Dosage gain is provided in a similar manner as described.

[0068] It will be appreciated that in other embodiments, the sidewall of the second component can be different, i.e., have a different shape or have different angles relative to a plane parallel to the surface of the first component over some or all of the length of the sidewall. For example, only a portion of the sidewall can have an angle α (e.g., less than 70 degrees). In some embodiments, the portion of the sidewall extending at angle α can extend over a substantial portion of the sidewall. In some embodiments, the portion of the sidewall extending at angle α can extend over a majority of the sidewall, i.e., over more than half of the sidewall. The portion of the sidewall extending at angle α can be at or near the substantially furthest point of the sidewall from the first component.

[0069] It will be appreciated that in other embodiments, angle α can be less than 85 degrees. In other embodiments, angle α can be 45 degrees. The optimal angle will depend on the thickness of the second component (as mentioned, it may be between 30 nm and 70 nm), and also on the feature size and spacing (which can also cover a wide range of sizes). It will also be appreciated that the sidewall can have different angles at different portions of the sidewall. For example, the sidewall can have a portion with a 90-degree angle near the first component, then a portion with a 45-degree angle (e.g., at approximately the midpoint of the sidewall), then another portion with a 90-degree angle away from the first component. As another example, the sidewall can have a portion with a 45-degree angle, then a portion with a 90-degree angle, then a portion with a 45-degree angle, and so on. Thus, for example, a substantial portion (or majority) of the sidewall extending at angle α (e.g., 45 degrees) need not be continuous, and there can be sections of the sidewall that do not have angle α.

[0070] In some embodiments, sidewall 56a and sidewall 56b (i.e., the further sidewall opposite sidewall 56a) can have the same angle α. More specifically, a further portion of the further sidewall can extend away from the first portion from the first component 52 at the same angle α. However, in other embodiments, sidewalls 56a and 56b can extend at different angles.

[0071] In some embodiments, the second component 54 can have one or more additional sidewalls (not shown) that can form different portions of the second component 54 and / or can extend in a direction perpendicular to the sidewalls 56a, 56b of the second component 54. The additional sidewall(s) can have the same angle α as the sidewall 56a (and sidewall 56b) or can have different angles. More specifically, the additional portions of the one or more additional sidewalls can extend away from the first portion of the first component 52 at the same angle α or at different angles.

[0072] Although the above description has been directed to a reflective phase-shift patterning device (i.e., for EUV radiation), the structure of the second component described above can also be used for a transmissive patterning device (such as for DUV radiation). For example, in this case, the first component can be transmissive. The transmissive patterning device can be a binary patterning device.

[0073] Although specific reference may be made herein to the use of lithographic apparatus in the manufacture of integrated circuits, 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 patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, and the like.

[0074] Although embodiments of the present invention may be specifically mentioned herein in the context of lithographic equipment, embodiments of the present invention may be used in other equipment. Embodiments of the present invention may form part of mask inspection equipment, metrology equipment, or any equipment that measures or processes objects such as wafers (or other substrates) or masks (or other patterning devices). These equipment may generally be referred to as lithographic tools. Such lithographic tools may use vacuum conditions or ambient (non-vacuum) conditions.

[0075] 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 is not limited to optical lithography and may be used in other applications, such as imprint lithography, where the context permits.

[0076] Where the context permits, embodiments of the present invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the present 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 transmitting information in a form readable by a machine (e.g., a computing device). For example, a machine-readable medium may include read-only memory (ROM); random access memory (RAM); magnetic storage media; optical storage media; flash memory devices; electrical, optical, acoustic, 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 understood that such descriptions are merely for convenience, and that such actions are in fact caused by a computing device, processor, controller, or other device executing the firmware, software, routines, instructions, etc., and that doing so may cause an actuator or other device to interact with the physical world.

[0077] Although specific embodiments of the present invention have been described above, it will be appreciated that the present invention may be practiced in ways other than those described. The foregoing description is intended to be illustrative rather than restrictive. Therefore, it will be apparent to those skilled in the art that modifications may be made to the described invention without departing from the scope of the claims set forth below.

Claims

1. A patterning device configured for use in a lithographic apparatus, the lithographic apparatus being configured to image a pattern of the patterning device onto a substrate via projection optics using radiation, the patterning device comprising: a first component for reflecting the radiation, and a second component covering at least part of a surface of the first component to provide a pattern on the patterning device and configured to at least partially absorb the radiation incident on the second component, wherein the second component includes a sidewall, wherein at least a portion of the sidewall extends from the first component at an angle relative to a plane parallel to the surface of the first component, and wherein the angle is less than 85 degrees, and wherein the sidewall has a curved shape; wherein at the farthest point of the side wall from the first component, the shape of the distal convex end portion of the second component is half a period of a sine curve or less.

2. The patterning device of claim 1, wherein the at least a portion of the sidewall is a substantial portion of the sidewall.

3. A patterning device according to claim 1 or 2, wherein the at least one portion is a majority of the side wall.

4. The patterning device of claim 1 or 2, wherein the sidewall extends away from the first component at the angle at approximately a midpoint of the sidewall.

5. The patterning device of claim 1 or 2, wherein the sidewall has the angle at a substantially furthest point of the sidewall away from the first component.

6. The patterning device of claim 1 or 2, wherein the sidewall extends away from the first component at the angle across the sidewall.

7. The patterning device of claim 1 or 2, wherein the angle is less than 70 degrees.

8. The patterning device of claim 1 or 2, wherein the angle is 45 degrees.

9. A pattern forming device according to claim 1 or 2, wherein the second part has a further side wall substantially opposite to the side wall of the second part, wherein at least a further portion of the further side wall extends away from the first part at the angle.

10. The patterning device of claim 9, wherein the angle at which the further sidewall extends from the first component is different from the angle at which the sidewall extends from the first component.

11. A pattern forming device according to claim 1 or 2, wherein the second component has one or more additional side walls, wherein at least one additional portion of the one or more additional side walls extends away from the first component at the angle.

12. The patterning device of claim 11, wherein the angle at which the one or more additional sidewalls extend from the first component is different from the angle at which the sidewalls extend from the first component.

13. The patterning device of claim 1 or 2, wherein the patterning device is at least one of a reflective patterning device, a transmissive patterning device, a binary patterning device, and an attenuated phase-shift patterning device.

Images