Optical systems and methods

Abstract

The optical system comprises an optical component configured to alter electromagnetic radiation and an electric motor configured to actuate the optical component. The electric motor includes a movable element containing a plurality of magnetic components connected to the optical component. The electric motor also includes a stator not connected to the movable element, which contains a plurality of electric components configured to actuate the optical component non-contact by receiving an electric current and interacting with the magnetic fields of the plurality of magnetic components.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims priority to European Application No. 23192387.1, filed on August 21, 2023, which is incorporated herein by reference in its entirety.

[0002] The present invention relates to optical systems and methods. In particular, the present invention relates to the use of an electric motor for non - contact operation of optical components. The present invention can be utilized in various optical systems including, but not limited to, lithography systems, optical measurement systems, and substrate processing systems.

Background Art

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

[0004] To project a pattern onto a substrate, a lithography apparatus can use electromagnetic radiation. The wavelength of this radiation determines the minimum size of the features that can be formed on the substrate. A lithography apparatus using extreme ultraviolet (EUV) radiation with a wavelength in the range of 4 - 20 nm (e.g., 6.7 nm or 13.5 nm) can be used to form smaller features on a substrate than, for example, a lithography apparatus using radiation with a wavelength of 193 nm. Other lithography apparatuses can use other wavelengths. For example, a deep ultraviolet (DUV) lithography apparatus can utilize ultraviolet radiation having a wavelength of, for example, 365, 248, 193, 157, or 126 nm.

Summary of the Invention

Problems to be Solved by the Invention

[0005] Like other types of optical devices such as optical measuring devices and substrate processing devices, lithography devices have optical components that must be operated during use in order to perform their function. It may be desirable to provide optical systems and methods that overcome or mitigate one or more problems related to the prior art, whether or not they are specified herein or elsewhere. [Means for solving the problem]

[0006] An optical system is provided according to a first aspect of the present disclosure. The optical system comprises an optical component configured to modify electromagnetic radiation. The optical system comprises an electric motor configured to actuate the optical component. The electric motor comprises a mover which includes a plurality of magnetic components connected to the optical component. The electric motor comprises a stator which is not connected to the mover, and the stator comprises a plurality of electric components configured to actuate the optical component non-contact by receiving an electric current and interacting with the magnetic fields of the plurality of magnetic components.

[0007] Known optical systems feature Lorentz actuators with a flexure positioned to keep the pins aligned with the motor. The flexure provides a physical connection between the optical component and the frame. This introduces dynamic stiffness, which is detrimental to the fine and / or rapid operation of the optical component. The flexure introduces stiffness that increases with increasing frequency of the optical component's movement and / or vibration (e.g., natural frequency or resonant frequency). This dynamic stiffness undermines the so-called "zero stiffness" concept that underlies Lorentz actuators. Furthermore, known Lorentz actuators are relatively bulky, heavy, and have complex interfaces and connections with the optical component, requiring considerable power requirements and complex control systems for operation.

[0008] The optical system of this disclosure advantageously avoids the need for flexure or other physical contact between the stator and the mover. This eliminates the dynamic stiffness associated with known Lorentz actuators, improving the fine and / or rapid operation of the optical components, thereby improving the performance of the optical system compared to known optical systems. Magnetic force control provided by multiple magnetic and electrical components advantageously offers a simplified, compact, and lightweight operating mechanism compared to known Lorentz actuators.

[0009] The number of electrical components can be greater than the number of degrees of freedom of the optical components.

[0010] Increasing the numerical aperture (NA) of some optical systems is beneficial. For example, lithography equipment can typically form smaller features as the numerical aperture increases. Optical systems with increased numerical apertures are sometimes referred to as hyper-numerical aperture (hyper-NA) optical systems in the art. Hyper-NA optical systems may require larger optical components to capture larger angles of incidence of electromagnetic radiation. To maintain control over the dynamic behavior of larger optical components (e.g., high-bandwidth natural frequencies or resonant characteristics), it may be necessary to significantly increase the mass of the optical components (e.g., by increasing the thickness of the optical components). For example, the mass of mirrors in hyper-NA lithography equipment is predicted to need to be about three times that of current non-hyper-NA mirrors to maintain the same dynamic behavior. Such an increase in mass poses problems in itself and is not considered feasible for all optical systems. For example, an increase in mass can lower the natural frequency or resonant frequency of the optical component, thereby introducing unwanted vibrations or movements (e.g., higher-order vibration frequency modes and the resulting deformation of the optical component) that can adversely affect the performance of the optical system.

[0011] The optical systems of this disclosure advantageously provide overactuation of optical components (i.e., systems with more actuation elements than the system's operating degrees of freedom). Multiple magnetic and electrical components can be used to counteract higher-order vibrational frequency modes and associated deformations of the optical components that result from increasing the size of the optical components to capture a wider range of incident angles of electromagnetic radiation. This makes it possible to keep the mass of the optical components substantially the same in a hyper-NA optical system (for example, without needing to increase the thickness of the optical components to achieve the same dynamic behavior).

[0012] The optical component may be a mirror. The movable element may be connected to the back surface of the mirror.

[0013] Mirrors are used in many optical systems to alter electromagnetic radiation (for example, to change the direction of propagation by reflection). Mirrors can undergo unwanted thermal deformation when interacting with electromagnetic radiation, which can negatively impact the performance of the optical system. Electric motors can, advantageously, actuate optical components to counteract and / or compensate for thermal deformation.

[0014] Optical components can also take other forms.

[0015] The optical component may be a transmissive optical component. The optical component may be a lens.

[0016] The optical component may be a diffractive optical component. The optical component may also be a diffraction grating.

[0017] The optical component may also be a polarizing optical component. The optical component may also be a polarizer.

[0018] Optical components may be configured to modify electromagnetic radiation in one or more ways.

[0019] Optical components may be configured to alter the direction of electromagnetic radiation propagation.

[0020] The optical component may be configured to change the cross-sectional shape (e.g., beam shape) of electromagnetic radiation.

[0021] The optical component may be configured to change the intensity distribution of electromagnetic radiation.

[0022] The optical component may be configured to change the phase of electromagnetic radiation.

[0023] The optical component may be configured to refract electromagnetic radiation.

[0024] The optical component may be configured to focus electromagnetic radiation.

[0025] The optical component may be configured to reflect electromagnetic radiation.

[0026] The optical component may be configured to diffract electromagnetic radiation.

[0027] The optical component may be configured to polarize electromagnetic radiation.

[0028] The optical component may be configured to attenuate electromagnetic radiation.

[0029] The optical component may be configured to scatter electromagnetic radiation.

[0030] The optical component may be configured to disperse electromagnetic radiation.

[0031] The optical component may be configured to modify extreme ultraviolet (EUV) electromagnetic radiation.

[0032] The optical component may be configured to modify deep ultraviolet (DUV) electromagnetic radiation. <00001IO The optical component may be configured to modify X-ray electromagnetic radiation.

[0034] The optical components may be configured to modify infrared electromagnetic radiation.

[0035] EUV radiation and / or DUV radiation and / or X-ray radiation and / or infrared radiation can be used to perform micro and / or rapid optical processes, such as EUV lithography, DUV lithography, soft X-ray substrate inspection, or infrared plasma generation in laser-generated plasma (LPP) EUV radiation sources. Such micro and / or rapid optical processes require corresponding micro and / or rapid operation of the optical components therein. The optical systems of this disclosure advantageously improve the operating precision and speed of the optical components, thereby improving the performance of the micro and / or rapid optical processes that utilize the optical systems.

[0036] The electric motor may be a planar motor.

[0037] Planar electric motors offer a significant improvement in the operating precision of optical components compared to known optical systems, thereby enabling fine control of higher-frequency vibrations and the resulting deformation of optical components. Planar electric motors also offer a significant improvement in the operating speed of optical components compared to known optical systems, thereby enabling rapid correction of unwanted movement and / or deformation of optical components.

[0038] The electric motor may be a reversing-plane motor.

[0039] The electric motor may be a three-phase electric motor.

[0040] The electric motor may be configured to translate the optical component. The electric motor may be configured to translate the optical component in any direction, for example, along three orthogonal axes.

[0041] The electric motor may be configured to rotate the optical component. The electric motor may be configured to rotate the optical component in any direction, for example, around three orthogonal axes.

[0042] The electric motor may be configured to deform the optical components.

[0043] Multiple magnetic components may be arranged to form a magnetic component array.

[0044] Multiple electrical components may be arranged to form an electrical component array.

[0045] The inclusion of magnetic component arrays and electrical component arrays advantageously improves the precision of the operational control of optical components.

[0046] Multiple magnetic components may include permanent magnets.

[0047] Multiple electrical components may include coils.

[0048] The magnetic component array may also be a Halbach magnet array.

[0049] The inventors have found that Halbach magnet arrays provide improvements in the precise and rapid operation control of optical components.

[0050] The electrical component array may include multiple layers. The electrical components of the first layer may be arranged perpendicular to the electrical components of the second layer.

[0051] The first layer may be configured to provide the operation of the optical component in a first direction, and the second layer may be configured to provide the operation of the optical component in a second direction perpendicular to the first direction.

[0052] The electric motor may be configured to levitate the optical components.

[0053] Non-contact operation of optical components by magnetic levitation advantageously avoids the dynamic stiffness associated with known Lorentz actuators, thereby improving the operational precision of optical components compared to known optical systems.

[0054] The stator may include permanent magnets configured to interact with the magnetic fields of multiple magnetic components of the movable component, thereby applying lift to the optical components.

[0055] Gravity compensation using permanent magnets significantly reduces the power requirements needed to levitate optical components. This reduces the thermal load associated with the operation of optical components, minimizes unwanted thermal deformation of the components, and leads to improved performance of the optical system.

[0056] The inventors have realized that the operation of optical components may not require the long-distance planar motion typically associated with known planar motors. Therefore, one or more permanent magnets can be introduced into the stator while maintaining the required operating range of the optical component. In other words, the inventors have realized that the reduced range of motion results in lower power requirements compared to known planar motors, and that gravity compensation using stator permanent magnets, which would not have been possible with known planar motors, can be introduced.

[0057] The stator's permanent magnet may be nested within one of several electrical components.

[0058] The stator's permanent magnet may be replaced by one of several electrical components.

[0059] Nesting the optical components within the electrical components, or replacing the electrical components with permanent magnets, favorably improves the levitation of the optical components without increasing power consumption or compromising the compact arrangement of the stator's electrical components.

[0060] The permanent magnet may be placed inside the coil.

[0061] The permanent magnets may be placed in the positions of the coils within the coil array.

[0062] The stator permanent magnets may form part of a stator permanent magnet array arranged to apply a substantially homogeneous lift force to the optical components.

[0063] Stator permanent magnet arrays improve the levitation of optical components without increasing power consumption or compromising the compact arrangement of electrical components in the stator.

[0064] The ratio of permanent magnets to electrical components in a stator permanent magnet array may be approximately 1 to 3.

[0065] The inventors have found that this ratio is particularly advantageous in improving the levitation of optical components without increasing power consumption or compromising the compact arrangement of electrical components in the stator.

[0066] The stator may contain approximately 200 or more electrical components per square meter.

[0067] The stator may contain approximately 40 or more electrical components.

[0068] Using such a large number of electrical components advantageously improves the overactuation of the optical components. This enhances the ability of the electric motor to counteract the higher-order frequency vibration modes of the optical components and the resulting deformations.

[0069] The movable element may contain approximately 600 or more magnetic components per square meter.

[0070] The movable element may contain approximately 160 or more magnetic components.

[0071] Using such a large number of magnetic components advantageously improves the overactuation of optical components. This enhances the electric motor's ability to counteract the higher-frequency vibration modes and associated deformations of the optical components.

[0072] There may be approximately one or more magnetic components per electrical component. There may be approximately four or fewer magnetic components per electrical component.

[0073] The inventors have found that these ratios are particularly advantageous in providing overactuation of optical components while limiting power consumption and associated thermal load.

[0074] Each magnetic component may occupy an area of ​​approximately 0.04m x approximately 0.04m or less.

[0075] The inventors have realized that the operation of optical components may not require the long-distance planar motion typically associated with planar motors. Therefore, the size of the magnetic component can be significantly reduced compared to that of known planar motors. Using such a small magnetic component advantageously enhances the compactness of the mover and contributes to improved overactuation of the optical component. This improves the electric motor's ability to counteract higher-frequency vibration modes and associated deformations of the optical component.

[0076] Each electrical component may occupy an area of ​​approximately 0.04m x approximately 0.12m or less.

[0077] The inventors have realized that the operation of optical components may not require the long-distance planar motion typically associated with planar motors. Therefore, the size of the electrical components can be significantly reduced compared to those of known planar motors. Using such small electrical components advantageously enhances the compactness of the stator and contributes to improved overactuation of the optical components. This improves the electric motor's ability to counteract higher-frequency vibration modes and associated deformations of the optical components.

[0078] The separation distance between adjacent magnetic components may be approximately 0.04 m or less.

[0079] Providing such a compact arrangement of magnetic components advantageously enhances the compactness of the movable part and contributes to improved overactuation of the optical components. This improves the electric motor's ability to counteract higher-frequency vibration modes and associated deformations of the optical components.

[0080] The separation distance between adjacent electrical components may be approximately 5 mm or less.

[0081] Providing such a compact arrangement of electrical components advantageously enhances the compactness of the stator and contributes to improved overactuation of optical components. This improves the electric motor's ability to counteract higher-order frequency vibration modes of optical components and the resulting deformations.

[0082] According to a second aspect of the present disclosure, a lithography apparatus is provided which is arranged to project a pattern onto a substrate from a patterning device. The lithography apparatus comprises an optical system according to the first aspect.

[0083] The optical system may form part of the illumination system.

[0084] The optical system may form part of the projection system.

[0085] The optical system may form part of the radiation source. The optical system may also form part of the CO2 beam path in the LPP source.

[0086] The optical system may form part of the measurement system.

[0087] The optical system may form part of the substrate inspection system.

[0088] The optical system may form part of the optical measurement system.

[0089] The optical system may form part of the alignment sensor.

[0090] The optical system may form part of the overlay sensor.

[0091] The optical system may form part of the optical aberration sensor.

[0092] A third aspect of this disclosure provides a method for operating an optical component. This method includes connecting a plurality of magnetic components to the optical component. This method includes arranging a plurality of electrical components that are not connected to the optical component. This method includes supplying electric current to the plurality of electrical components so that they interact with the magnetic fields of the plurality of magnetic components to operate the optical component non-contact.

[0093] This method may include providing more electrical components than the number of operating degrees of freedom of the optical components.

[0094] This method may include levitating the optical components.

[0095] This method may include providing a permanent magnet configured to interact with the magnetic fields of multiple magnetic components to exert a lift force on an optical component. [Brief explanation of the drawing]

[0096] Embodiments of the present invention are described below merely as examples, with reference to the accompanying schematic drawings. [Figure 1] This figure shows a lithography system including a lithography apparatus, a radiation source, and two electric motors configured to operate optical components in accordance with this disclosure. [Figure 2] This figure schematically illustrates an optical system comprising an optical component configured to modify electromagnetic radiation, and an electric motor configured to operate the optical component in accordance with this disclosure. [Figure 3] This figure shows a flowchart of a method for operating an optical component according to this disclosure. [Modes for carrying out the invention]

[0097] Figure 1 schematically depicts a lithography system including a radiation source SO, a lithography apparatus LA, and two electric motors 120 configured to operate two different optical components 11, 13. The radiation source SO is configured to generate an EUV radiation beam B and to supply the EUV radiation beam B to the lithography apparatus LA. The lithography 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.

[0098] The illumination system IL is configured to adjust the EUV radiation beam B before it is incident on the patterning device MA. To this end, the illumination system IL may include a faceted field mirror device 10 and a faceted pupil mirror device 11. Both the faceted field mirror device 10 and the faceted pupil mirror device 11 provide the EUV radiation beam B with a desired cross-sectional shape and a desired intensity distribution. In addition to, or instead of, the illumination system IL may include other mirrors or devices. In the example in Figure 1, the faceted pupil mirror device 11 is actuated by an electric motor 120. The electric motor 120 comprises a movable element 130 including a plurality of magnetic components (shown in Figure 2) connected to the faceted pupil mirror device 11. The electric motor 120 comprises a stator 150 not connected to the movable element 130, which includes a plurality of electrical components (shown in Figure 2) configured to interact with the magnetic fields of the plurality of magnetic components by receiving an electric current, thereby actinguating the faceted pupil mirror device 11 non-contact.

[0099] After being adjusted in this manner, the EUV radiation beam B interacts with the patterning device MA. As a result of this interaction, a patterned EUV radiation beam B' is produced. The projection system PS is configured to project the patterned EUV radiation beam B' onto a substrate W. For this purpose, the projection system PS may comprise several 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' to form an image with features smaller than the 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 shown in Figure 1 as having only two mirrors 13, 14, it may include a different number of mirrors (e.g., 6 or 8 mirrors). In the example in Figure 1, one of the mirrors 13 of the projection system PS is actuated by an electric motor 120. The electric motor 120 comprises a movable element 130 including several magnetic components (shown in Figure 2) connected to the mirror 13. The electric motor 120 includes a stator 150 that is not connected to the movable element 130, and this stator includes several electrical components (shown in Figure 2) configured to interact with the magnetic fields of several magnetic components by receiving an electric current, thereby operating the mirror 13 non-contact. The electric motor 120 will be described in more detail below with reference to Figure 2. The lithography system may include further electric motors 120 for non-contact operation of other optical components therein, such as optical components of a radiation source SO and / or optical components of an optical measurement system such as alignment sensors, level sensors, optical aberration sensors, and / or overlay sensors.

[0100] The substrate W may include a previously formed pattern. In this case, the lithography apparatus LA aligns the image formed by the patterned EUV radiation beam B' with the previously formed pattern on the substrate W.

[0101] A relative vacuum, i.e., a small amount of gas (e.g., hydrogen) at a pressure well below atmospheric pressure, may be provided within the radiation source SO, the illumination system IL, and / or the projection system PS.

[0102] The radiation source SO may be a laser-generated plasma (LPP) source, a discharge-generated plasma (DPP) source, a free-electron laser (FEL), or any other radiation source capable of generating EUV radiation.

[0103] Figure 2 schematically depicts an optical system 100 comprising an optical component 110 configured to modify electromagnetic radiation (not shown). In the example in Figure 2, the optical component 110 is a mirror. Mirror 110 may correspond, for example, to one of the illumination system mirrors 10, 11 of the lithography apparatus LA in Figure 1. In another example, mirror 110 may correspond to one of the mirrors 13, 14 of the projection system PS of the lithography apparatus LA in Figure 1. In either of these examples, mirror 110 may be configured to modify extreme ultraviolet (EUV) electromagnetic radiation as part of an EUV lithography process. As another alternative example, mirror 110 may correspond to a mirror (not shown) located within the radiation source SO of the lithography apparatus LA in Figure 1. In this example, mirror 110 may be configured to modify infrared radiation as part of plasma and / or EUV radiation generation in a laser-generated plasma (LPP) EUV radiation source. The optical system 100 may form part of an optical measurement system. For example, the optical system 100 may form part of an alignment sensor configured to determine the alignment between the substrate W and the patterning device MA. In another example, the optical system 100 may form part of an overlay sensor configured to determine the overlay error between different layers of the substrate W. In yet another example, the optical system 100 may form part of an optical aberration sensor, such as an interference wavefront sensor configured to determine the optical aberration of the projection system PS and / or the illumination system IL. In a further alternative example, the mirror 110 may not form part of the lithography apparatus, but instead form part of another optical system, such as an optical measurement system for substrate inspection. In this example, the mirror 110 may be configured to modify X-ray (e.g., soft X-ray) electromagnetic radiation as part of the substrate inspection process. In any of these examples, the mirror 110 may be configured to modify electromagnetic radiation by changing the direction of propagation of the electromagnetic radiation through reflection. The mirror 110 may be configured to modify electromagnetic radiation by changing the cross-sectional shape (e.g., beam shape) of the electromagnetic radiation and / or changing the intensity distribution of the electromagnetic radiation.

[0104] The optical system 100 includes an electric motor 120 configured to actuate an optical component 110. In the example of Figure 2, the electric motor 120 is an inverting planar motor. The electric motor 120 may be, for example, a three-phase electric motor. The electric motor 120 includes a movable element 130 which contains a plurality of magnetic components 140 connected to the optical component 110. The movable element 130 may be made of a metal such as aluminum. The movable element 130 may be made of a ceramic material. The plurality of magnetic components 140 may be connected to the movable element 130 by an adhesive or the like. In the example of Figure 2, the movable element 130 is connected to the back surface of the mirror 110. The electric motor 120 also includes a stator 150 which is not connected to the movable element 130 and contains a plurality of electrical components 160 which are configured to actuate the optical component 110 in a non-contact manner by receiving an electric current and interacting with the magnetic field of the plurality of magnetic components 140. The stator 150 may be made of a non-ferromagnetic material such as aluminum. Multiple magnetic components 140 are arranged to form a magnetic component array, and multiple electrical components 160 are arranged to form an electrical component array.

[0105] The magnetic components 140 may include, for example, a ferromagnetic material such as iron. In the example in Figure 2, the magnetic components 140 are permanent magnets, and the permanent magnets 140 are oriented to have alternating polarities. That is, the south pole of the first magnet 140 in the magnetic component array is connected to the optical component 110, and the north poles of adjacent magnets 140 in the magnetic component array are connected to the optical component 110. The magnets 140 can form a grid array. For example, further rows of magnets 140, not visible in Figure 2, may extend in a direction parallel to the Y axis. Other arrangements are also possible. For example, the magnetic component array may be a Halbach magnet array.

[0106] In the example in Figure 2, the electrical component 160 includes a coil configured to receive current. The coil 160 is wound around a pole 162. The coils 160 may form a grid array. For example, further rows of coils 160, not visible in Figure 2, may extend in a direction parallel to the Y-axis. The electrical component array may roughly correspond to the magnetic component array in terms of shape and extent. The number of components 140, 160 in each array may vary. The relative positions of the components 140, 160 in each array may be in phase or out of phase (i.e., aligned or misaligned) along the range of the movable element 130 and the stator 150.

[0107] The electrical component array may include multiple layers (not shown). For example, a second coil layer may be provided on top of the coil layer 160 shown in Figure 2. The electrical components 160 of the first electrical component layer may be arranged perpendicular to the electrical components 160 of the second layer. Different layers of electrical components 160 may be configured to control different aspects of the operation of the optical component 110. For example, the first layer of electrical components 160 may be configured to provide operation of the optical component 110 in a first direction X, and the second electrical component layer (not shown) may be configured to provide operation of the optical component 110 in a second direction Y perpendicular to the first direction X.

[0108] The number of magnetic components 140 and electrical components 160 present in the electric motor 120 can be selected depending at least in part on the size of the optical component 110, and / or the weight of the optical component 110, and / or the degree of the desired operating motion (e.g., translation, and / or rotation, and / or deformation). The optical component 110 may have a diameter of about 0.1 m or more. The optical component 110 may have a diameter of about 1 m or less. For example, the optical component 110 may have a diameter of about 0.5 m. The optical component 110 may have a thickness of about 0.05 m or more. The optical component 110 may have a thickness of about 0.2 m or less. For example, the optical component 110 may have a thickness of about 0.1 m. The optical component 110 may have a weight of about 25 kg or more. The optical component 110 may have a weight of about 100 kg or less. For example, the optical component 110 may have a weight of about 50 kg. The electric motor 120 may be configured to translate and / or deform the optical component 110 over a distance of approximately 0.5 mm or more. The electric motor 120 may be configured to translate and / or deform the optical component 110 over a distance of approximately 2 mm or less. For example, the electric motor 120 may be configured to translate and / or deform the optical component 110 over a distance of approximately 1 mm. The electric motor 120 may be configured to translate and / or deform the optical component 110 over a distance smaller than the dimensions of a single magnetic component 140. The electric motor 120 may be configured to rotate and / or deform the optical component 110 at an angle of approximately 0.5 mrad or more. The electric motor 120 may be configured to rotate and / or deform the optical component 110 at an angle of approximately 2 mrad or less. For example, the electric motor 120 may be configured to rotate and / or deform the optical component 110 at an angle of approximately 1 mrad.

[0109] The stator 150 may contain approximately 200 or more electrical components 160 per square meter. For example, if mirror 110 corresponds to any of mirrors 10, 11, 13, or 14 in Figure 2, the stator 150 may contain approximately 40 or more electrical components 160. The movable element 130 may contain approximately 600 or more magnetic components 140 per square meter. For example, if mirror 110 corresponds to any of mirrors 10, 11, 13, or 14 in Figure 2, the movable element 130 may contain approximately 160 or more magnetic components 140. There may be approximately 2 or more magnetic components 140 for each electrical component 160. There may be approximately 4 or fewer magnetic components 140 for each electrical component 160. For example, there may be approximately 3 magnetic components 140 for each electrical component 160. The ratio of magnetic components 140 to electrical components 160 may depend at least in part on the shape and / or range of the electrical components 160. For example, electrical component 160 may include a circular coil or an elongated elliptical coil. In the example of a circular coil, there may be more magnetic components 140 than electrical components 160. In the example of an elongated elliptical coil, the number of magnetic components 140 may be substantially equal to the number of electrical components 160. Each magnetic component 140 may occupy an area of ​​approximately 0.04 m × approximately 0.04 m or less. Each electrical component 160 may occupy an area of ​​approximately 0.04 m × approximately 0.12 m or less. The separation distance between adjacent magnetic components 140 (e.g., the pitch of the magnetic component array) may be approximately 0.04 m or less. The pitch of the magnetic component array may be constant. The pitch of the magnetic component array may be substantially equal to the dimensions of a single magnetic component 140. The separation distance between adjacent electrical components 160 (e.g., the pitch of the electrical component array) may be approximately 5 mm or less. The pitch of the electrical component array may be constant. The pitch of the magnetic component array may be different from the pitch of the electrical component array.

[0110] The number of electrical components 160 can be greater than the number of operating degrees of freedom of the optical component 110. For example, if the optical component 110 has seven or more degrees of freedom (e.g., three translational degrees of freedom: forward / backward, up / down, and left / right; three rotational degrees of freedom: yaw, pitch, and roll; and one or more deformation degrees of freedom), the number of electrical components 160 can be eight or more. This provides overactuation of the optical component 110 (i.e., there are more acting elements than operating degrees of freedom). Multiple magnetic components 140 and electrical components 160 can be used to at least partially account for and / or counteract undesirable effects of higher-order frequency vibration modes of the optical component 110 and the associated movements that may occur during use. Increasing the number of electrical components 160 can increase the degree of possible overactuation. For example, to enable 12 operating degrees of freedom, the electric motor 120 can be equipped with approximately 40 electrical components 160.

[0111] The electric motor 120 may be configured to levitate the optical component 110. The electromagnetic force acting between the magnetic component 140 and the electric component 160 may apply a lift force 180 to the movable element 130 substantially vertically (i.e., parallel to the Z-axis) against gravity, thereby contributing to the levitation of the optical component 110 on the stator 150. Alternatively, the stator 150 may include one or more permanent magnets 170 configured to interact with the magnetic fields of the multiple magnetic components 140 of the movable element 130, thereby applying a lift force 180 to the optical component 110. In the example in Figure 2, only two permanent magnets 170 of the stator 150 are shown, but in reality, many more may be present. In the example in Figure 2, the two permanent magnets 170 of the stator 150 are substantially aligned with the two magnetic components 140 of the movable element 130. This alignment may occur, for example, once for every three electric components 160. The permanent magnets 170 are nested within different coils 160. Alternatively, the permanent magnets 170 of the stator 150 may replace one of the multiple electrical components 160. That is, one or more permanent magnets 170 of the stator 150 may be positioned in a location within the electrical component array that would otherwise be occupied by the electrical components 160. The permanent magnets 170 of the stator 150 may form part of a stator permanent magnet array arranged to apply a spatially substantially homogeneous lift 180 to the optical components 110. The ratio of permanent magnets 170 to electrical components 160 in the stator 150 may be approximately 1 to approximately 3.

[0112] The electric motor 120 can be configured to actuate the optical component 110 in various ways. The electric motor 120 can be configured to translate the optical component 110 in any direction, for example, along three orthogonal axes X, Y (the Y axis is perpendicular to both the X and Z axes and is therefore not visible in Figure 2), and Z. The electric motor 120 can be configured to rotate the optical component in any direction, for example, around three orthogonal axes X, Y, and Z. For example, when used to actuate a faceted field mirror device 10 and / or a faceted pupil mirror device 11 as shown in Figure 1, the electric motor 120 can translate and / or rotate the mirrors 10, 11 to modify the EUV radiation beam B to have a desired cross-sectional shape and a desired intensity distribution. As another example, when used to operate mirrors 13, 14 of a projection system PS as shown in Figure 1, the electric motor 120 may translate and / or rotate the mirrors 13, 14 to change the propagation direction of the patterned EUV radiation beam B' so that the patterned EUV radiation beam B' is directed towards the substrate W held by the substrate table WT. The electric motor 120 may be configured to deform optical components 110. For example, any of the above mirrors 10, 11, 13, and 14 may undergo undesirable thermal deformation when interacting with EUV radiation, which may adversely affect the performance of the lithography apparatus LA. The electric motor 120 may be configured to deform one or more of the mirrors 10, 11, 13, and 14 to counteract and / or account for undesirable thermal deformation, thereby improving the performance of the lithography apparatus LA.

[0113] When an electric current is supplied to the electrical component 160, an electromagnetic force is generated, which can be used to operate the optical component 110. The generated electromagnetic force may depend, at least in part, on which electrical component 160 receives the current, and / or the direction of the current supplied to the electrical component 160, and / or the magnitude of the current supplied to the electrical component 160. For example, by supplying a first current to a first electrical component 160 in a first direction, the magnetic field strength in the first direction can be increased, while by supplying a second current to a second electrical component 160 in a second direction, the magnetic field in the other direction can be decreased. This imbalance in the magnetic field may cause the movable element 130 to move relative to the stator 150. As the movable element 130 moves relative to the stator 150, the relative positions of the magnetic component 140 and the electrical component 160 change, which in turn effectively adjusts the magnetic field strength between each magnetic component 140 and electrical component 160. The current supplied to the electrical component 160 may change as the movable element 130 moves relative to the stator 150. For each electrical component 160, the relationship between the direction and magnitude of the current supplied to the electrical component 160 and the resulting electromagnetic force acting on the magnetic component 140 on the movable element 130 can be established, for example, by analytical and / or numerical models. By establishing such relationships for various different currents and electrical components 160, and by considering the inverse of the relationships, any desired electromagnetic force and / or torque can be converted into current. Since the relationships are at least partially position-dependent, the distribution of current across the electrical components 160 can be adjusted according to the position of the movable element 130 relative to the stator 150. One or more position sensors (not shown) may be provided to measure the position of the movable element 130 relative to the stator 150. Measurements performed by one or more position sensors can be used to at least partially determine the current supply to the electrical components 160 in order to operate the optical component 110 in a desired manner.

[0114] The electric motor 120 can be considered a low-power electric motor 120 compared to known planar motors. For example, the electric motor 120 may be configured to provide lower acceleration and / or lower speed and / or a narrower range of motion for the optical component 110 compared to a planar motor not used to actuate the optical component. For example, a known planar motor can actuate a non-optical component with a mass of about 100 kg in about 100 ms -2 It may be configured to move an optical component with an acceleration of approximately 500 mm over a distance of approximately 500 mm. In contrast, the electric motor 120 of the present disclosure moves an optical component with a mass of approximately 50 kg over approximately 0.1 ms -2 It can be configured to move over a distance of approximately 1 mm with an acceleration of .

[0115] Figure 3 shows a flowchart of a method for operating an optical component according to this disclosure. A first step 200 of the method includes connecting a plurality of magnetic components to the optical component. A second step 210 of the method includes arranging a plurality of electrical components that are not connected to the optical component. A third step 220 of the method includes supplying current to the plurality of electrical components so that they interact with the magnetic fields of the plurality of magnetic components to operate the optical component non-contact. The method may include an optional step of providing more electrical components than the number of operating degrees of freedom of the optical component. The method may include an optional step of levitating the optical component. The method may include an optional step of providing permanent magnets configured to interact with the magnetic fields of the plurality of magnetic components to apply lift to the optical component.

[0116] The optical component 110 has so far been described and explained as a mirror. However, it will be understood that the optical component 110 can take other forms, and that the electric motor can be used to operate and / or levitate any given optical component that requires operation in a non-contact manner. The optical component may be a transmissive optical component, such as a lens. The optical component may be a diffractive optical component, such as a diffraction grating. The optical component may be a polarizing optical component, such as a polarizer.

[0117] Optical components 110 have so far been described and portrayed as modifying electromagnetic radiation by reflecting it and changing the direction of its propagation. However, it will be understood that optical components 110 can take other forms and be configured to modify electromagnetic radiation in other ways. For example, an optical component may be configured to change the direction of propagation of electromagnetic radiation through refraction. An optical component may be configured to change the phase of electromagnetic radiation. An optical component may be configured to diffract electromagnetic radiation. An optical component may be configured to polarize electromagnetic radiation. An optical component may be configured to attenuate electromagnetic radiation. An optical component may be configured to scatter electromagnetic radiation. An optical component may be configured to disperse electromagnetic radiation. In general, the electric motor 120 described herein may be used for non-contact operation of any optical component configured to modify electromagnetic radiation in any given way.

[0118] While this specification may contain specific references to the use of lithography equipment in IC manufacturing, it should be understood that the lithography equipment described herein may have other applications. Possible other applications include the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memory, flat panel displays, liquid crystal displays (LCDs), and thin-film magnetic heads.

[0119] While this specification may provide specific references to embodiments of the present invention in the context of lithography apparatus, embodiments of the present invention can be used in other apparatuses. Embodiments of the present invention may form part of a mask inspection apparatus, a measuring apparatus, or any apparatus for measuring or processing objects such as wafers (or other substrates) or masks (or other patterning devices). These apparatuses may generally be referred to as lithography tools. Such lithography tools may operate under vacuum conditions or ambient (non-vacuum) conditions.

[0120] While specific references may have been made above regarding the use of embodiments of the present invention in the context of photolithography, it will be understood that, to the extent the context permits, the present invention is not limited to photolithography and can be used in other applications such as imprint lithography. While specific references may have been made above regarding the use of embodiments of the present invention in the context of EUV lithography, it will be understood that the optical systems of this disclosure can form part of other types of lithography equipment, such as deep ultraviolet (DUV) lithography equipment using ultraviolet radiation with wavelengths of 365, 248, 193, 157, or 126 nm.

[0121] Where 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 in a machine-readable medium that can be read and executed by one or more processors. The machine-readable medium may include any mechanism for storing or transmitting information in a format readable by a machine (e.g., a computing device). For example, the machine-readable medium may include read-only memory (ROM), random-access memory (RAM), magnetic storage media, optical storage media, flash memory devices, electrically, optical, acoustic, or other forms of propagating signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. Furthermore, firmware, software, routines, and instructions may be described herein as performing certain actions. However, it should be understood that such descriptions are for convenience only, and such actions are actually the result of a computing device, processor, controller, or other device executing firmware, software, routines, instructions, etc., which may cause actuators or other devices to interact with the physical world in doing so.

[0122] While specific embodiments of the present invention have been described above, it will be understood that the present invention can be practiced in ways other than those described. The above description is illustrative and not limiting. Therefore, it will be apparent to those skilled in the art that modifications to the described invention can be made without departing from the claims set forth below.

Claims

1. Optical components configured to modify electromagnetic radiation, The system includes an electric motor configured to operate the aforementioned optical component, The aforementioned electric motor is A movable element including a plurality of magnetic components connected to the optical component, An optical system comprising a stator which includes a plurality of electrical components that are not connected to the movable element and are configured to interact with the magnetic fields of the plurality of magnetic components by receiving an electric current, thereby operating the optical components in a non-contact manner.

2. The optical system according to claim 1, wherein the number of electrical components is greater than the number of operating degrees of freedom of the optical components.

3. The optical system according to claim 1 or 2, wherein the optical component is a mirror and the movable element is connected to the back surface of the mirror.

4. The optical system according to any one of claims 1 to 3, wherein the optical component is configured to modify either extreme ultraviolet electromagnetic radiation, deep ultraviolet electromagnetic radiation, X-ray electromagnetic radiation, or infrared electromagnetic radiation.

5. The optical system according to any one of claims 1 to 4, wherein the electric motor is a planar motor.

6. The optical system according to any one of claims 1 to 5, wherein the plurality of magnetic components are arranged to form a magnetic component array, and the plurality of electrical components are arranged to form an electrical component array.

7. The optical system according to claim 6, wherein the magnetic component array is a Halbach magnet array.

8. The optical system according to claim 6 or 7, wherein the array of electrical components comprises a plurality of layers, and the electrical components of the first layer are arranged perpendicular to the electrical components of the second layer.

9. The optical system according to any one of claims 1 to 8, wherein the electric motor is configured to levitate the optical component.

10. The optical system according to any one of claims 1 to 9, wherein the stator comprises permanent magnets configured to interact with the magnetic fields of the plurality of magnetic components of the movable, thereby applying lift to the optical components.

11. The optical system according to claim 10, wherein the permanent magnet of the stator is nested in one of the plurality of electrical components, or the permanent magnet of the stator replaces one of the plurality of electrical components.

12. The optical system according to claim 10 or 11, wherein the permanent magnets of the stator form part of a stator permanent magnet array arranged to apply a substantially homogeneous lift force to the optical component.

13. The optical system according to claim 12, wherein the ratio of the permanent magnets to the electrical components in the stator permanent magnet array is about 1 to about 3.

14. The optical system according to any one of claims 1 to 13, wherein the stator includes approximately 200 or more of the electrical components per square meter.

15. The optical system according to any one of claims 1 to 14, wherein the movable element includes approximately 600 or more of the magnetic components per square meter.

16. The optical system according to any one of claims 1 to 15, wherein there are approximately 1 to 4 magnetic components for each of the aforementioned electrical components.

17. The optical system according to any one of claims 1 to 16, wherein each magnetic component occupies an area of ​​approximately 0.04 m x approximately 0.04 m or less.

18. The optical system according to any one of claims 1 to 17, wherein each electrical component occupies an area of ​​approximately 0.04 m x approximately 0.12 m or less.

19. The optical system according to any one of claims 1 to 18, wherein the separation distance between adjacent magnetic components is approximately 0.04 m or less.

20. The optical system according to any one of claims 1 to 19, wherein the separation distance between adjacent electrical components is approximately 5 mm or less.

21. A lithography apparatus comprising an optical system according to any one of claims 1 to 20, arranged to project a pattern onto a substrate from a patterning device.

22. A method for operating optical components, Connecting multiple magnetic components to the optical component, The arrangement of multiple electrical components that are not connected to the aforementioned optical component, The process involves supplying current to the aforementioned plurality of electrical components, thereby interacting with the magnetic fields of the plurality of magnetic components to operate the optical component without contact, A method that includes this.

23. The method according to claim 22, comprising providing more electrical components than the number of operating degrees of freedom of the optical component.

24. The method according to claim 22 or 23, comprising levitating the optical component.

25. The method according to any one of claims 22 to 24, comprising providing a permanent magnet configured to interact with the magnetic fields of the plurality of magnetic components to apply a lift force to the optical component.

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