Spectral Feature Control Device

Abstract

A deep ultraviolet laser system includes a line narrowing module having multiple prisms, where an incident laser beam from a laser first interacts with a first prism, then interacts with a second prism after the first prism. The second prism has two distinct portions, including a first portion designed to operate at and enable a higher bandwidth of the incident laser beam, and a second portion designed to operate at and enable a lower bandwidth of the incident laser beam. The second prism is movable between a first position where the laser beam interacts with the first portion and a second position where the laser beam interacts with the first portion. The second prism is movable by translation using an activation mechanism controlled by a controller to change the target bandwidth of the laser beam.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Application No. 63 / 407,509, filed September 16, 2022, which is incorporated by reference in its entirety into this specification.

[0002] The disclosed subject matter relates to an apparatus for controlling the spectral characteristics, such as bandwidth and wavelength, of a light beam output from a light source that provides light to a lithographic exposure apparatus. [Background technology]

[0003] In semiconductor lithography (or photolithography), the manufacture of integrated circuits (ICs) requires a variety of physical and chemical processes to be performed on a semiconductor (e.g., silicon) substrate (also called a wafer). A photolithography exposure tool or scanner is a machine that applies a desired pattern to a target portion of the substrate. The wafer is generally aligned with the orthogonal X-axis of the scanner. L and Y L The wafer is fixed to the stage so that it extends along a plane defined by the Z direction of the scanner. The wafer is illuminated with a light beam having a wavelength in the deep ultraviolet (DUV) range. L The scanner moves along the axis that matches the Z direction. L The direction is horizontal X L -Y L It is perpendicular to the plane.

[0004]

[0004] Precise knowledge of the spectral characteristics or properties (e.g., wavelength and / or bandwidth) of a light beam output from a light source, such as a laser, is important in many scientific and industrial applications. For example, precise knowledge of the bandwidth of a light source can be used to control the minimum feature size or critical dimension (CD) in deep ultraviolet (DUV) optical lithography. The critical dimension is the feature size that is printed on a semiconductor substrate (also called a wafer), and therefore fine size control of the CD can be required. Summary of the Invention

[0005] In some general aspects, a spectral feature control device includes a spectral feature selection module including a plurality of prisms disposed at an optical plane and configured to receive and pass an incident light beam along the optical plane, the plurality of prisms being positioned at an input side of the spectral feature selection module and including a first prism configured to receive the incident light beam, a second prism configured to receive the light beam exiting the first prism, the second prism having two or more portions, each portion configured to enable a distinct bandwidth range of the light beam, and an activation mechanism configured to move the second prism along a direction relative to the optical plane, thereby selecting a bandwidth range of the light beam by positioning a particular portion of the second prism at the optical plane.

[0006]

[0006] Embodiments may include one or more of the following features. For example, the two or more portions may be stacked on top of each other relative to the optical flat surface. The spectral feature selection module may be configured to select a wavelength in a deep ultraviolet (DUV) range of the light beam. The control device may also include a first actuator configured to rotate the first prism. Rotating the first prism may primarily change the optical magnification of the light beam. The first actuator may be configured to rotate the first prism through an angular range, and the activation mechanism may be configured to move the second prism, thereby adjusting the optical magnification of the light beam in a range from about 10x to about 50x. Adjusting the optical magnification of the light beam in a range from about 10x to about 50x primarily adjusts the bandwidth of the light beam in a range from about 1000 femtometers (fm) to about 250 fm. The first actuator may include one or more of a motor, a valve, a pressure control device, a piezoelectric device, a linear motor, a hydraulic actuator, and a voice coil.

[0007] The second prism may include a first portion stacked on a second portion, the first portion configured to interact with a higher bandwidth range of the light beam when positioned at the optical plane, and the second portion configured to interact with a lower bandwidth range of the light beam when positioned at the optical plane. The first portion may have a first geometry, and the second portion may have a second geometry different from the first geometry. Positioning the first portion in the light path may enable an optical magnification of the light beam ranging from about 10x to about 19x, and positioning the second portion in the light path may enable an optical magnification of the light beam ranging from about 20x to about 50x. The first portion may have a first right-angled triangular geometry including one or more dimensions, and the second portion may have a second right-angled triangular geometry including one or more dimensions different from one or more dimensions of the first right-angled triangular geometry. The first portion may include a wedge prism with at least one surface plane in the light path, the surface plane having a uniform, flat geometry. 11. The control device of claim 10, wherein the first portion comprises a wedge prism with at least one surface plane in the optical path, the surface plane having a convex or concave geometry.

[0008]

[0008] The activation mechanism configured to move the second prism along a direction relative to the optical plane may include moving the second prism perpendicular to the optical plane to select a bandwidth range of the light beam. The spectral feature selection module may also include a third prism and a fourth prism, and a diffractive optical element arranged to interact with the light beam in a Littrow configuration. Adjusting the first and second prisms may primarily change at least the optical magnification of the light beam to enable selection of the bandwidth of the light beam. The control device may also include a third actuator configured to rotate the third prism and a fourth actuator configured to rotate the fourth prism. Rotating the third and fourth prisms may primarily change the center wavelength of the light beam. The third prism and the fourth prism may each include or be made of calcium fluoride or magnesium fluoride. The third prism and the fourth prism may each be a right-angled triangular prism.

[0009] The two or more portions of the second prism may include a first and a second portion, where the first portion may include a material having a first refractive index and the second portion may include a material having a second refractive index different from the first refractive index. The two or more portions of the second prism may include a first and a second portion, where the first portion may include a material having a first refractive index and the second portion may include a material having a second refractive index the same as the first refractive index. The first prism and the second prism may each include or be made of calcium fluoride or magnesium fluoride. The activation mechanism may include a pneumatic actuator or an electromechanical actuator.

[0010] In another general aspect, a method for controlling the wavelength and bandwidth of a light beam generated by an optical oscillator is described, the method including selecting a bandwidth range from a set of distinct bandwidth ranges, including positioning a distinct portion of a second prism having a plurality of distinct portions at an optical plane through which the light beam passes, controlling an optical magnification of the light beam generated from the optical oscillator to a desired optical magnification based on the selected bandwidth range, including passing the light beam through a first prism closest to the optical oscillator and the distinct portion positioned at the optical plane of the second prism, adjusting an angle at which the light beam travels, including passing the light beam through at least a third prism, and selecting the wavelength and bandwidth of the light beam based on the adjusted angle, including impinging the light beam from the at least third prism on a dispersive optical element positioned to interact with the light beam in a Littrow configuration, and selecting the wavelength and bandwidth of the light beam based on the optical magnification of the light beam impinging on the dispersive optical element.

[0011] In another general aspect, a deep ultraviolet (DUV) laser system includes a line narrowing module having multiple prisms, such that an incident laser beam from a laser first interacts with a first prism and then, after the first prism, with a second prism. The second prism has two distinct stacked portions, including a first portion designed to interact with a higher bandwidth of the incident laser beam and a second portion designed to interact with a lower bandwidth of the incident laser beam. The second prism is movable between a first position where the laser beam interacts with the first portion and a second position where the laser beam interacts with the first portion. The second prism is movable by translation using an activation mechanism controlled by a controller to change the target bandwidth of the laser beam.

[0012]

[0012] Embodiments may include one or more of the following features: For example, the first portion may have a first shape and the second portion may have a second shape different from the first shape; the activation mechanism may be a pneumatic or electrical activation mechanism.

[0013] In another general aspect, an illumination system includes a light source configured to generate a light beam and a spectral feature control device arranged to interact with the light beam generated by the light source. The spectral feature control device includes a dispersive optical element, a beam expander including a plurality of prisms arranged in an optical path between the dispersive optical element and an aperture through which the light source light beam can pass, the dispersive optical element and the beam expander being arranged such that the light source light beam interacts with the aperture, the prisms, and the dispersive optical element along the optical path, and an activation mechanism configured to move a second prism of the beam expander along a direction non-parallel to the optical path to position a particular geometrically distinct portion of the second prism in the optical path, thereby selecting a bandwidth range of the light beam. The second prism is positioned adjacent to the first prism closest to the aperture. [Brief explanation of the drawings]

[0014] [Figure 1]

[0014] FIG. 1 is a block diagram of a spectral feature control device including a beam expander having a second prism with a first portion and a second portion. [Figure 2A]

[0015] FIG. 2 is a perspective view of an embodiment of the second prism of FIG. 1. [Figure 2B]

[0016] 2B is an exploded perspective view of the second prism of FIG. 2A, showing details of the first and second portions. [Figure 2C]

[0017] FIG. 2C is a top view of the spectral feature selection module with a beam expander with a second prism of FIGS. 2A and 2B (the plane of the page is the optical plane). [Figure 2D]

[0018] FIG. 2C is a side view of the second prism of FIGS. 2A to 2C and an activation mechanism physically coupled to the second prism for moving or translating the second prism so that the first portion is in the optical plane. [Figure 2E]

[0019] FIG. 2C is a side view of the second prism of FIGS. 2A to 2C and an activation mechanism physically coupled to the second prism for moving or translating the second prism so that a second portion is in an optical plane. [Figure 3A]

[0020] FIG. 2D is a top view of the spectral feature selection module of FIG. 2C, wherein the second prism is positioned such that the second portion is at the optical plane, and the first prism is at a first extreme position that produces a light beam having a bandwidth based on a total magnification determined at least in part by the position of the first prism and the position of the second portion at the optical plane. [Figure 3B]

[0021] FIG. 2D is a top view of the spectral feature selection module of FIG. 2C, where the second prism is positioned such that the second portion is at the optical plane and the first prism is at a second extreme position that produces a light beam having a bandwidth based on a total magnification determined at least in part by the position of the first prism and the position of the second portion at the optical plane. [Figure 4A]

[0022] FIG. 2D is a top view of the spectral feature selection module of FIG. 2C, where the second prism is positioned such that the first portion is at the optical plane, and the first prism is at a first extreme position that produces a light beam having a bandwidth based on a total magnification determined at least in part by the position of the first prism and the position of the second portion at the optical plane. [Figure 4B]

[0023] FIG. 2D is a top view of the spectral feature selection module of FIG. 2C, with the second prism positioned such that the first portion is at the optical plane and the first prism in a second extreme position that produces a light beam having a bandwidth based on a total magnification determined at least in part by the position of the first prism and the position of the second portion at the optical plane. [Figure 5A]

[0024] 1. FIG. 4 is a perspective view of another embodiment of the second prism of FIG. [Figure 5B]

[0025] 5B is an exploded perspective view of the second prism of FIG. 5A, showing details of the first and second portions. [Figure 6A]

[0026] 1. FIG. 4 is a perspective view of another embodiment of the second prism of FIG. [Figure 6B]

[0027] 6B is an exploded perspective view of the second prism of FIG. 6A, showing details of the first and second portions. [Figure 7A]

[0028] 1. FIG. 4 is a perspective view of another embodiment of the second prism of FIG. [Figure 7B]

[0029] 7B is an exploded perspective view of the second prism of FIG. 7A, showing details of the first and second portions. [Figure 8A]

[0030] 1. FIG. 4 is a perspective view of another embodiment of the second prism of FIG. [Figure 8B]

[0031] 8B is an exploded perspective view of the second prism of FIG. 8A, showing details of the first and second portions. [Figure 9]

[0032] 2 is a block diagram of a photolithography system including an illumination system that generates a pulsed light beam directed to a photolithography exposure tool, the pulsed light beam being formed from the light beam generated by the light source of FIG. 1. [Figure 10]

[0033] 10 is a graph illustrating the optical spectrum of a light beam produced from the illumination system of FIG. 9, the optical spectrum being defined by the center wavelength and bandwidth of the light beam. DETAILED DESCRIPTION OF THE INVENTION

[0015]

[0034] Referring to FIG. 1 , the spectral feature control device 100 includes a spectral feature selection module 130 configured to receive a light beam 115 generated by a light source 101 through an aperture 135. The spectral feature selection module 130 includes optical mechanisms or components 102, 104, 106, 108, and 110, which may be arranged in a Littrow configuration. The optical components 102, 104, 106, 108, and 110 are configured to interact with the light beam 115 received within the spectral feature selection module 130. The optical components 102, 104, 106, 108, and 110 may be further configured to modify and adjust the spectral characteristics (such as bandwidth and wavelength) of the light beam 115. The light beam 115 may have a wavelength in the deep ultraviolet (DUV) range. The light beam 115 may be a pulsed light beam used to pattern microelectronic features on a substrate (or wafer) received in a photolithography exposure apparatus, as discussed in more detail below.

[0016]

[0035] The spectral feature selection module 130 may be configured with a beam expander 120 comprised of optical components 102, 104, 106, and 108. The optical components 102, 104, 106, and 108 may be configured as transmissive and refractive optical elements, such as optical prisms. Specifically, the optical components 102, 104, 106, and 108 may be configured and implemented as a first prism 102, a second prism 104, a third prism 106, and a fourth prism 108, respectively. Each prism 102, 104, 106, and 108 is configured to refract and redirect the light beam 115 as it passes through the body of the prism 102, 104, 106, and 108. Light beam 115 is optically expanded by beam expander 120 as it travels from aperture 135 towards grating 110 , and is optically compressed by beam expander 120 as it travels from grating 110 towards aperture 135 .

[0017]

[0036] The optical components 102, 104, 106, and 108 are made of one or more materials that allow the transmission of the wavelength of the light beam 115. For example, the optical components 102, 104, 106, and 108 can be made of materials such as calcium fluoride or magnesium fluoride that are compatible with the deep UV wavelength of the light beam 115 and allow the optical components 102, 104, 106, and 108 to be implemented as transmissive prisms. When the optical components 102, 104, 106, and 108 are transmissive prisms, the optical components 102, 104, 106, and 108 function to disperse, deflect, and redirect the light beam 115 as it passes through the body of the corresponding prism. Furthermore, the spectral feature selection module 130 can also be configured with a diffractive optical element 110, which can be, for example, an optical grating with a diffractive surface 112. The grating 110 is designed to disperse, diffract, and reflect the light beam 115. Grating 110 and diffractive surface 112 of grating 110 are made of a material that is compatible with the wavelength of light beam 115 and serves to reflect and diffract light beam 115 that comes into contact with diffractive surface 112. For example, grating 110 (and surface 112) can be made of calcium fluoride or magnesium fluoride.

[0018]

[0037] 1, within the beam expander 120, the optical components 102, 104, 106, 108, and 110 can be arranged sequentially to define an optical plane. When received within the spectral feature control device 100, the light beam 115 propagates through the optical plane. In this example, the optical plane is approximately the XY plane. Specifically, within the spectral feature selection module 130, the first prism 102 can be positioned closest to the aperture 135, followed by the second prism 104, the third prism 105, and the fourth prism 108, with the fourth prism 108 being positioned farthest from the aperture 135. Thus, when light beam 115 is received into spectral feature selection module 130 through aperture 135, it is first received by beam expander 120, specifically by first prism 102, and then passes successively through second prism 104, third prism 105, and fourth prism 108. Light beam 115 exits beam expander 120 through fourth prism 108 and is directed towards grating 110. Diffractive surface 112 of grating 110 diffracts and reflects light beam 115 back through beam expander 120 and back into aperture 135 in the reverse order that light beam 115 was received. Specifically, light beam 115 reflected from diffractive surface 112 is received by fourth prism 108, then third prism 104, second prism 104, and finally first prism 102, which directs light beam 115 out of spectral feature selection module 130 through aperture 135. As light beam 115 travels in this reverse direction from grating 110 through spectral feature selection module 130, light beam 115 is optically compressed by each of optical components 108, 106, 104, and 102.

[0019]

[0038] Initially, as described above, when light beam 115 enters spectral feature selection module 130 through aperture 135, light beam 115 is directed toward beam expander 120 and received by first prism 102 disposed within beam expander 120. First prism 102 can be configured to rotate within its optical plane, thereby changing or adjusting one or more spectral characteristics of light beam 115. Specifically, rotation of first prism 102 within its optical plane primarily adjusts the optical magnification of light beam 115 at grating 110. The optical magnification of light beam 115 is the ratio of the lateral width Wo of light beam 115 exiting beam expander 120 (on its path to grating 110) to the lateral width Wi of light beam 115 entering beam expander 120 (from light source 101). Adjusting the optical magnification of light beam 115 at grating 110 adjusts the bandwidth of light beam 115. The third prism 106 and the fourth prism 108 can each be configured to rotate within an optical plane to thereby change or adjust one or more spectral characteristics of the light beam 115. Specifically, the rotation of the third prism 106 and the fourth prism 108 primarily adjusts the angle of incidence of the light beam 115 at the grating 110. Adjusting the angle of incidence of the light beam 115 at the grating 110 adjusts the wavelength of the light beam 115.

[0020]

[0039] In conventional spectral feature control devices, the bandwidth of the light beam 115 is adjusted primarily by rotating the first prism 102. Therefore, the bandwidth range achievable by such conventional spectral feature control devices is limited by the rotation of the first prism 102 and also by the geometry of the first prism 102. This is because the rotation of the first prism 102 primarily adjusts the optical magnification of the light beam 115 at the grating 110 within a certain limited range. For example, in some embodiments, the rotation of the first prism 102 can adjust the optical magnification of the light beam 115 at the grating 110 from about 19x to about 50x. This optical magnification range corresponds to a bandwidth range of about 200 femtometers (fm) to about 500 fm, respectively. Therefore, in this example, if a bandwidth of 300 fm is initially desired, the conventional spectral feature control device would not be able to adjust the first prism 102 to obtain a bandwidth of 800 fm.

[0021]

[0040] The spectral feature control device 100 is designed to adjust the bandwidth of the light beam 115 over a wider range than is possible with conventional devices by converting the second prism 104 into a multi-section second prism 104. Specifically, the second prism 104 includes a first section 104-1 and a second section 104-2 that can be stacked along the Z direction relative to the first section 104-1. When the first section 104-1 is in the optical plane XY (as shown in the configuration of FIG. 1 and similarly shown in FIG. 2D for the first section 204-1 of the second prism 204), the first section 104-1 is designed and configured to interact with the light beam 115 and thereby operate in a first bandwidth range. When the first section 104-1 is in the optical plane XY, the second section 104-2 is not in an optical plane and does not interact with the light beam 115, as shown in FIG. 1. When the second portion 104-2 is in the optical plane XY (as shown in FIG. 2E for the second portion 204-2 of the second prism 204), the second portion 104-2 is designed and configured to interact with the light beam 115 and thereby operate in a second bandwidth range that is different from the first bandwidth range. When the second portion 104-2 is in the optical plane XY, the first portion 104-1 is not in an optical plane and is not interacting with the light beam 115. For example, the first portion 104-1 can be configured to receive and interact with a higher bandwidth range of the light beam 115, and the second portion 104-2 can be configured to receive and interact with a lower bandwidth range of the light beam 115. By dividing or separating the second prism 104 into these differently designed portions 104-1 and 104-2 and selecting the first portion for a first bandwidth range and the second portion for a second bandwidth range, the spectral feature control device 100 operates over a wider bandwidth range without requiring modification of the device 100 or changes to components within the device 100 while the light source 101 is in operation.

[0022]

[0041] Furthermore, the increased bandwidth range allows for a reduction in edge placement errors (EPEs) that may occur on a substrate receiving the light beam 115. Specifically, edge placement errors may occur in features patterned on the substrate by the light beam 115. Edge placement errors are differences between the intended features in the layout on the substrate and the printed features. Specifically, the light beam 115 must pattern small features in precise locations on the substrate. For example, the features may be lines, and the lines have right and left edges. Misalignment (or EPEs) may occur if the shape and form of the lines and their right and / or left edges are not accurate or are not properly positioned. Furthermore, if one or more EPE issues occur in the manufacturing flow of a substrate, devices fabricated on a substrate with all of these EPE issues may be subject to electrical shorts and reduced yields, potentially resulting in the failure of the entire chip formed on the substrate. To mitigate EPE issues, the bandwidth of the light beam 115 must be increased. The spectral feature controller 100 can increase the bandwidth of these light beams 115 using a second prism 104 with two differently designed portions 104-1 and 104-2.

[0023]

[0042] In some embodiments, the geometry and shape of the second portion 104-2 are different from the geometry and shape of the first portion 104-1. Examples of possible different geometries and shapes are discussed below with reference to Figures 2A and 2B, 3A and 3B, 4A and 4B, and 7A and 7B. In some embodiments, the material of the second portion 104-2 is different from the material of the first portion 104-1, as discussed with reference to Figures 8A and 8B. In some embodiments, the scale and placement of the second portion 104-2 can be different from the scale and placement of the first portion 104-1, as discussed with reference to Figures 5A and 5B.

[0024]

[0043] 1 , the optical components 102, 104, 106, 108, and 110 of the spectral feature selection module 130 may be configured with and mechanically coupled to corresponding actuation systems 102A, 104A, 106A, 108A, and 110A. The actuation systems 102A, 104A, 106A, 108A, and 110A may be configured to move the corresponding optical components 102, 104, 106, 108, and 110 to adjust one or more spectral characteristics of the light beam 115. Generally, each of the actuation systems 102A, 104A, 106A, 108A, and 110A is a mechanical device for moving or controlling the corresponding optical component. The actuation systems 102A, 104A, 106A, 108A, and 110A may receive energy from the control module 140 and convert the energy into some movement imparted to the corresponding optical component. For example, actuation systems 102A, 106A, 108A, 110A can be or include force devices and rotation stages for rotating one or more of prisms or grating 110. Actuation systems 102A, 106A, 108A, 110A can include, for example, motors such as stepper motors, valves, pressure control devices, piezoelectric devices, linear motors, hydraulic actuators, voice coils, etc. Although actuation system 110A is shown relative to grating 110, grating 110 can alternatively be fixed at various orientations. Similarly, either prism 106 or 108 can alternatively be fixed while the other is movable (rotatable) in the optical plane.

[0025]

[0044] The actuation system 104A mechanically coupled to the second prism 104 can be configured as an activation mechanism that can be or include, for example, a pneumatic actuator or an electromechanical actuator. The activation mechanism 104A can be configured to translate the first portion 104-1 and the second portion 104-2 of the second prism 104 along a Z direction perpendicular to the XY plane of the optical plane, thereby moving the first portion 104-1 and the second portion 104-2 into and out of the optical plane (XY plane). The first portion 104-1 and the second portion 104-2 are configured to operate by selecting different bandwidth ranges, thereby enabling the activation mechanism 104A to select different bandwidth ranges.

[0026]

[0045] The control module 140 may comprise electronics in the form of any combination of hardware, firmware, and software. The control module 140 may be configured to provide energy or power to the actuation systems 102A, 104A, 106A, 108A, 110A and to control and monitor the movement of the corresponding optical components 102, 104, 106, 108, 110 to which the actuation systems are mechanically coupled. Additionally, the control module 140 may also be configured to receive control signals from a control system 145. The control system 145 may also be configured to communicate with the light source 101. The control system 145 may be configured to send control signals to the control module 140, which may include, for example, specific commands to operate or control one or more of the actuation systems 102A, 104A, 106A, 108A, 110A and thereby determine the position of the optical components 102, 104, 106, 108, 110.

[0027]

[0046] 2A-2C, an embodiment 204 of the second prism 104 is shown. In FIG. 2A, the second prism 204 is shown in a perspective view separated from the beam expander 120, and in FIG. 2B, the second prism 204 is shown in an exploded perspective view (transparent to show all surfaces) separated from the beam expander. In FIG. 2C, the second prism 204 is shown disposed within an embodiment 220 of the beam expander 120. The second prism 204 includes a second portion 204-2 stacked on a first portion 204-1.

[0028]

[0047] In this example, second portion 204-2 has a triangular geometry and first portion 204-1 has a wedge geometry. Second portion 204-2 can be a triangular prism, and in some examples, the triangle can be a right-angled triangle. First portion 204-1 can be a wedge prism with a wedge angle Φ in the range of 0° to 45° (FIG. 2B).

[0029]

[0048] The beam expander 220 also includes a first prism 202, which is the first optical component 102, a third prism 206, which is the third optical component 106, a fourth prism 208, which is the fourth optical component 108, and a grating 210 positioned to interact with the light beam 115 passing through the beam expander 220. The prisms 202, 204, 206, 208 generally increase in size of the surface area that interacts with the light beam 115 from the first prism 202, which is closest to the aperture 135, to the fourth prism 208, which is furthest from the aperture 135.

[0030]

[0049] First portion 204-1 comprises a front surface 205-1 facing first prism 202 and a rear surface 207-1 facing third prism 206 when first portion 204-1 is positioned in the optical plane (XY plane) ( FIG. 2B ). Note that while surface 205-1 is referred to as the “front,” this term refers to its position relative to first prism 202; similarly, while surface 207-1 is referred to as the “rear,” this term refers to its position relative to third prism 206. When first portion 204-1 is in the optical plane (XY plane), light beam 115 enters front surface 205-1 when exiting first prism 202 and exits rear surface 207-1 when traveling toward third prism 206. On the return path (from grating 210), light beam 115 enters rear face 207-1 as it exits third prism 206 and exits front face 205-1 as it travels towards first prism 202.

[0031]

[0050] The second portion 204-2 comprises a front surface 205-2 facing the first prism 202 and a rear surface 207-2 facing the third prism 206 when the second portion 204-2 is positioned in the optical plane (XY plane) ( FIG. 2B ). Note that while surface 205-2 is referred to as the “front,” this term refers to its position relative to the first prism 202; similarly, while surface 207-2 is referred to as the “rear,” this term refers to its position relative to the third prism 206. When the second portion 204-2 is in the optical plane (XY plane), the light beam 115 enters the front surface 205-2 when exiting the first prism 202 and exits the rear surface 207-2 when traveling toward the third prism 206. On the return path (from grating 210), light beam 115 enters rear face 207-2 as it exits third prism 206 and exits front face 205-2 as it travels towards first prism 202.

[0032]

[0051] As discussed above with reference to FIG. 1 , the second prism 104 is physically coupled to the activation mechanism 104A. An example embodiment 204A of the activation mechanism 104A is shown in FIG. 2C . The operation of the activation mechanism 204A is shown in FIGS. 2D and 2E . The activation mechanism 204A can be any suitable mechanism configured to move the prism 204 along the Z direction such that the first portion 204-1 and the second portion 204-2 are alternately positioned in the optical plane (XY plane), also denoted as OP in FIGS. 2D and 2E . The activation mechanism 204A can be a device including a linear motor, a pressure-controlled device, a piezoelectric device, a hydraulic or pneumatic actuator, or an electromagnetic actuator. As shown in Figure 2D, upon receiving an instruction from control module 140 to position first portion 204-1 of prism 204 at optical plane OP, activation mechanism 204A translates prism 204 along the +Z direction so that first portion 204-1 of prism 204 is positioned at optical plane OP. As shown in Figure 2E, upon receiving an instruction from control module 140 to position second portion 204-2 of prism 204 at optical plane OP, activation mechanism 204A translates prism 204 along the -Z direction so that second portion 204-2 of prism 204 is positioned at optical plane OP.

[0033]

[0052] 2C , an embodiment 202A of the first actuator 102A is configured to rotate the first prism 202 in an optical plane (the XY plane) about an actuation axis parallel to the Z direction, which may correspond to or be parallel to the axis of the first prism 202. Generally, the first actuator 102A is configured to rotate the first prism 202 within an angular range of 0° to approximately 20°. Additionally, an embodiment 206A of the third actuator 106A is configured to rotate the third prism 206 in the optical plane (the XY plane) about an actuation axis (e.g., the axis of the third prism 206) parallel to the Z direction. Finally, embodiment 208A of fourth actuator 108A is configured to rotate fourth prism 208 in the optical plane (XY plane) about an actuation axis (e.g., the axis of fourth prism 208) parallel to the Z direction. Each actuation system 202A, 206A, 208A can be or can comprise either a force device and a rotation stage for rotating its associated prism 202, 206, 208. Each actuation system 202A, 206A, 208A can include, for example, a motor such as a stepper motor, one or more valves, a pressure control device, a piezoelectric device, a linear motor, a hydraulic actuator, a voice coil, etc.

[0034]

[0053] 3A and 3B, the second prism 204 is positioned so that the second portion 204-2 is in the optical plane (XY plane) as shown in FIG. 2E. In this example, the first prism 202 rotates between a first position P(A) shown in FIG. 3A and a second position P(B) shown in FIG. 3B. The second position P(B) is obtained by rotating the first prism 202 about an actuation axis that, in this particular example, does not coincide with the center of gravity of the prism 202 (which defines the prism axis), thus causing the prism 202 to rotate and translate. This change in position of the first prism 202 causes the light beam 115 to impinge on the front surface of the first prism 202 at a different angular position in the arrangement of FIG. 3B relative to the arrangement of FIG. 3A. This change in the position of impact on the front surface of the first prism 202 causes a cascading change in the path or direction of the light beam 115 directed to each of the second prism 204, the third prism 206, and the fourth prism 208, as well as a cascading change in the optical magnification of each of the second prism 204, the third prism 206, and the fourth prism 208, so that the light beam 115 approaches the grating 210 at a different angle and a different lateral extent Wo in the arrangement of Figure 3B compared to the arrangement of Figure 3A by the time the light beam 115 reaches the grating 210.

[0035]

[0054] Specifically, as shown in FIG. 3A , when the first prism 202 is at position P(A), the total optical magnification of the grating 210 is 20x. That is, the ratio of the width Wo to the width Wi is 20. This optical magnification is due to the fact that the first prism 202 is positioned at the first position P(A) and the second portion 204-2 of the second prism 204 is positioned at the optical plane. On the other hand, as shown in FIG. 3B , when the first prism 202 is at position P(B), the total optical magnification of the grating 210 is 50x. That is, the ratio of the width Wo to the width Wi is 50. This optical magnification is due to the fact that the first prism 202 is positioned at the first position P(B) and the second portion 204-2 of the second prism 204 is positioned at the optical plane.

[0036]

[0055] 4A and 4B, the second prism 204 is positioned such that the first portion 204-1 is in the optical plane (XY plane) as shown in FIG. 2D. The first prism 202 can rotate between a first position P(A) shown in FIG. 4A and a second position P(B) shown in FIG. 4B. When the first prism 202 is in the position P(A) shown in FIG. 4A, the total optical magnification of the grating 210 is 10x. That is, the ratio of the width Wo to the width Wi is 10. This optical magnification is due to the first prism 202 being positioned at the first position P(A) and the first portion 204-1 of the second prism 204 being positioned at the optical plane. On the other hand, when the first prism 202 is in the second position P(B) shown in FIG. 4B, the total optical magnification of the grating 210 is 19x. That is, the ratio of the width Wo to the width Wi is 19. This optical magnification is achieved by the first prism 202 being disposed at the first position P(B) and the first portion 204-1 of the second prism 204 being disposed at the optical plane.

[0037]

[0056] Therefore, adjustment of the total optical magnification is affected by the first actuator 202A adjusting the position of the first prism 202 in the optical plane and the activation mechanism 204A adjusting the position of the second prism 204 in the Z direction perpendicular to the optical plane, as well as by the control of the control module 140. At an optical magnification of 20x (FIG. 3A), the bandwidth of the light beam 115 may be approximately 480 fm. At an optical magnification of 50x (FIG. 3B), the bandwidth of the light beam 115 may be approximately 250 fm. At an optical magnification of 10x (FIG. 4A), the bandwidth of the light beam 115 may be approximately 1000 fm. At an optical magnification of 19x (FIG. 4B), the bandwidth of the light beam 115 may be approximately 520 fm. The actual bandwidth value can be fine-tuned around a specific bandwidth value by a few tens of fm from the initial bandwidth of the incident light beam 115 by controlling the initial incidence conditions of the light beam 115, so that there can be overlap at any bandwidth value, and any target value within about 250 to 1000 fm can be achieved by the spectral feature controller 100. In this way, the beam expander 220 (which may be implemented in the spectral feature controller 100) allows the selection of two different bandwidth ranges (about 250 to 500 fm or about 500 to 1000 fm) and, in general, a much wider bandwidth range.

[0038]

[0057] The change in optical magnification in the two different configurations (FIGS. 3A / 3B and 4A / 4B) is due to the different geometries of first portion 204-1 and second portion 204-2. Unlike second portion 204-2, which is a right-angle prism, first portion 204-1 is a wedge-shaped prism with two elongated surface planes: front surface 205-1 and rear surface 207-1. These two surface planes are oriented relative to each other at an angle (wedge angle Φ) that is different from the angles oriented by front surface 205-2 and rear surface 207-2 of second portion 204-2. This is more clearly shown in FIG. 2B. Because the first portion 204-1 has a different geometry from the second portion 204-2, the first portion 204-1 modifies the optical properties of the light beam 115 passing through it differently than the second portion 204-2, thereby enabling the selection of different bandwidth ranges that cannot be achieved by simply orienting the first prism 202 within the optical plane OP with a single-portion second prism (conventional design). Specifically, comparing the arrangement of FIG. 4B with that of FIG. 3B, it is clear that the light beam 115 impinges on the front surface 205-1 of the first portion 204-1 (see FIG. 2A) in FIG. 4B differently from the way the light beam 115 impinges on the first surface 205-2 of the second portion 204-2 (see FIG. 2A) in FIG. 3B. Specifically, the light beam 115 experiences different angular positions upon entering the second prism 204 in these two arrangements. Light beam 115 also experiences different angular positions in these two configurations as it exits second prism 204. This causes additional cascading changes in the optical magnification of light beam 115 as it passes through third prism 206 and fourth prism 208, which manifests as an overall change in the optical magnification of light beam 115 at grating 210 in the configuration of Figure 4B relative to the configuration of Figure 3B.

[0039]

[0058] Other embodiments of the second prism 104 are possible. For example, as shown in Figures 5A and 5B, an embodiment 504 of the second prism 104 includes a first portion 504-1 that is a first triangular prism and a second portion 504-2 that is a second triangular prism having a different shape / scale than the first triangular prism. Additionally, the second triangular prism 504-2 is oriented at a different angle than the first triangular prism 504-1 such that a front surface 505-2 of the second triangular prism 504-2 is at a different angle than a front surface 505-1 of the first triangular prism 504-1.

[0040]

[0059] As shown in FIGS. 2A and 2B, the front surface 205-1 of the wedge prism (first portion) 204-1 is flat. In another embodiment, as shown in FIGS. 6A and 6B, the front surface 605-1 of the wedge prism (first portion) 604-1 is convex. Specifically, the embodiment 604 of the second prism 104 may include a first portion 604-1, which is a wedge prism, and a second portion 604-2, which is a triangular prism, and the triangular prism 604-2 may be a right-angled triangular prism. The wedge prism 604-1 includes a convex front surface 605-1 and a rear surface 607-1. When the wedge prism 604-1 is positioned at an optical plane, the light beam 115 from the aperture 135 first enters the front surface 605-1 and then exits the rear surface 607-1. The convex (front) surface 605-1 of wedge prism 604-1 serves to focus light beam 115 and provides additional flexibility for controlling the magnification and size or lateral extent of light beam 115 as it interacts with grating 210. Triangular prism 604-2 comprises a front surface 605-2 and a rear surface 607-2. When triangular prism 604-2 is positioned at an optical plane, light beam 115 from aperture 135 first enters front surface 605-2 and then exits rear surface 607-2.

[0041]

[0060] In another embodiment, as shown in Figures 7A and 7B, the front surface 705-1 of the wedge prism (first portion) 704-1 is concave. Specifically, the second prism 104 embodiment 704 may include a first portion 704-1 that is a wedge prism and a second portion 704-2 that is a triangular prism, with the triangular prism 704-2 being a right-angled triangular prism. The wedge prism 704-1 includes a front surface 705-1 that is concave and a rear surface 707-1. When the wedge prism 704-1 is positioned at an optical plane (as shown in Figures 4A and 4B), the light beam 115 from the aperture 135 first enters the front surface 705-1 and then exits the rear surface 707-1. The concave (front) surface 705-1 of wedge prism 704-1 serves to diverge light beam 115 and provides additional flexibility for controlling the magnification and size or lateral extent of light beam 115 as it interacts with grating 210. Triangular prism 704-2 comprises a front surface 705-2 and a rear surface 707-2. When triangular prism 704-2 is positioned at an optical plane (as shown in FIGS. 3A and 3B ), light beam 115 from aperture 135 first enters front surface 705-2 and then exits rear surface 707-2.

[0042]

[0061] 8A and 8B, another embodiment 804 of the second prism 104 is shown. The second prism 804 comprises a first portion 804-1 and a second portion 804-2 stacked on top of the first portion. The shape of the first portion 804-1 may be the same as the shape of the first portion 804-2, but the material used for the second portion 804-2 is different from the material used for the first portion 804-1. In this manner, the light beam 115 behaves differently in each of the first portion 804-1 and the second portion 804-2. Using different materials for the second portion 804-2 and the first portion 804-1 may allow for a slight increase in the bandwidth range when using the same shape, but it is also possible to use different materials for the second portion 204-2 / 504-2 / 604-2 / 704-2 relative to the corresponding first portion 204-1 / 504-1 / 604-1 / 704-1 to increase the bandwidth range of those beam expanders.

[0043]

[0062] Referring to FIG. 9 , the spectral feature controller 100 is implemented in a photolithography system 950. The photolithography system 950 includes an illumination system 960 that generates a pulsed light beam 962 having a wavelength nominally at a center wavelength (determined by the angle of incidence of the light beam 115 at the grating 110 of FIG. 1 ). The pulsed light beam 962 is directed to a photolithography exposure apparatus 970. The pulsed light beam 962 is formed from a light beam 115 generated by a light source 101. The pulsed light beam 962 is used to pattern microelectronic features on a substrate 972 housed in the apparatus 970. The illumination system 960 includes a light source 101 that generates the pulsed light beam 962 at a pulse repetition rate required by the apparatus 970. The illumination system 960 includes a control system 145 that communicates with the light source 101, the spectral feature controller 100, and other mechanisms within the illumination system 960, including a metrology system 964. The control system 145 also communicates with the photolithography exposure apparatus 970 via a lithography controller 974. The light beam 962 is directed through a beam preparation system 966, which may include optical elements that modify the behavior of the light beam 962, such as reflective or refractive optical elements, optical pulse stretchers, or optical apertures or shutters.

[0044]

[0063] The pulses of light beam 962 are centered around a wavelength (determined by the angle of incidence of light beam 115 at grating 110 in FIG. 1 ), which is in the deep ultraviolet (DUV) range, which may include wavelengths from about 100 nanometers (nm) to about 400 nm, for example. The size of the microelectronic features patterned on substrate 972 depends on the center wavelength of light beam 962; the lower the center wavelength, the smaller the minimum feature size or critical dimension. For a wavelength of light beam 962 of 248 nm or 193 nm, the minimum feature size may be, for example, 50 nm or less. The bandwidth of light beam 962 may be the actual instantaneous bandwidth of the optical spectrum of light beam 962. A representation 1080 of the optical spectrum of light beam 962 is shown in FIG. 10 , along with a representation of the bandwidth BW and center wavelength λ. The optical spectrum 1080 contains information about how the optical energy or power of light beam 962 is distributed across various wavelengths or frequencies.

[0045]

[0064] The spectral feature controller 100 is disposed at a first end of the light source 101 to interact with the light beam 115. The light beam 115 is a light beam generated at one end of a resonator within the light source 101. In some embodiments, the light source 101 may be a dual-stage light source including a first stage having a master oscillator and a second stage having a power amplifier. The master oscillator (MO) generates a first light beam that is passed to the power amplifier via optical elements including relay optics. The power amplifier (PA) receives the first light beam and optically amplifies the first light beam to form the output light beam 962. In such a configuration of the light source 101, the spectral feature controller 100 may be positioned to receive the first light beam of the master oscillator. The master oscillator (MO) typically includes a gain medium where amplification occurs and an optical feedback mechanism, such as an optical resonator. The power amplifier (PA) typically includes a gain medium where amplification occurs when the first light beam from the master oscillator is seeded. The spectral feature controller 100 receives the light beam 115 from the master oscillator and allows fine tuning of the spectral features, such as the center wavelength and bandwidth, of the light beam 115 at a relatively low output pulse energy. The power amplifier amplifies the output from the master oscillator (first light beam) to obtain the necessary power for the light beam 962 for use in the photolithography exposure tool 970. Examples of such light sources 101 are described and discussed in U.S. Pat. No. 10,416,471, entitled "Spectral Feature Controller," which is incorporated herein by reference in its entirety.

[0046]

[0065] The embodiments can be further described using the following clauses. 1. A spectral feature control device comprising: a spectral feature selection module having a plurality of prisms disposed at an optical plane and configured to receive and pass an incident light beam along the optical plane, the plurality of prisms comprising: a first prism positioned at the input side of the spectral feature selection module and configured to receive the incident light beam; a second prism configured to receive the light beam exiting the first prism, the second prism comprising two or more portions, each portion configured to allow a distinct bandwidth range of the light beam; and an activation mechanism configured to select a bandwidth range of the light beam by moving the second prism along a direction relative to the optical plane, thereby positioning a particular portion of the second prism at the optical plane. 2. The control device of clause 1, wherein two or more parts are stacked on top of each other with respect to the optical plane. 3. The control device of clause 1, wherein the spectral feature selection module is configured to select wavelengths in the deep ultraviolet (DUV) range of the light beam. 4. The control device of clause 1, further comprising a first actuator configured to rotate the first prism. 5. The control device of clause 4, wherein rotation of the first prism thereby changes the optical magnification of the light beam. 6. The control device of clause 4, wherein the first actuator is configured to rotate the first prism through a range of angles, and the activation mechanism is configured to move the second prism, thereby adjusting the optical magnification of the light beam in a range of about 10x to about 50x. 7. The control device of clause 6, wherein adjusting the optical magnification of the light beam in a range of about 10x to about 50x thereby adjusting the bandwidth of the light beam in a range of about 1000 femtometers (fm) to about 250 fm. 8. The control device of clause 4, wherein the first actuator includes one or more of a motor, a valve, a pressure control device, a piezoelectric device, a linear motor, a hydraulic actuator, and a voice coil. 9. The control device of clause 1, wherein the second prism comprises a first portion stacked on top of a second portion, the first portion configured to interact with a higher bandwidth range of the light beam when positioned at the optical plane, and the second portion configured to interact with a lower bandwidth range of the light beam when positioned at the optical plane. 10. The control device of clause 9, wherein the first portion has a first geometry and the second portion has a second geometry different from the first geometry. 11. The control device of clause 9, wherein the first portion being positioned in the optical path allows for an optical magnification of the light beam in a range of about 10x to about 19x, and the second portion being positioned in the optical path allows for an optical magnification of the light beam in a range of about 20x to about 50x. 12. The control device of clause 11, wherein the first portion comprises a first right-angled triangular geometry including one or more dimensions, and the second portion comprises a second right-angled triangular geometry including one or more dimensions different from the one or more dimensions of the first right-angled triangular geometry. 13. The control device of clause 10, wherein the first part includes a wedge prism with at least one surface plane in the optical path, the surface plane having a uniform, flat geometry. 14. The control device of clause 10, wherein the first portion includes a wedge prism with at least one surface plane in the optical path, the surface plane having a convex or concave geometry. 15. The control device of clause 2, wherein the activation mechanism is configured to move the second prism along a direction relative to the optical plane, including moving the second prism perpendicular to the optical plane to select a bandwidth range of the light beam. 16. The control device of clause 1, wherein the spectral feature selection module further comprises a third prism and a fourth prism, and a diffractive optical element positioned to interact with the light beam in a Littrow configuration. 17. The control device of clause 16, wherein adjustment of the first and second prisms primarily changes at least the optical magnification of the light beam to allow selection of the bandwidth of the light beam. 18. A third actuator configured to rotate the third prism; a fourth actuator configured to rotate the fourth prism; 18. The control device of clause 17, wherein rotation of the third and fourth prisms changes the central wavelength of the light beam. 19. The control device of clause 18, wherein the third prism and the fourth prism each comprise calcium fluoride or magnesium fluoride. 20. The control device of clause 19, wherein the third prism and the fourth prism are right-angled triangular prisms. 21. The control device of clause 1, wherein the two or more portions of the second prism include a first and a second portion, the first portion including a material having a first refractive index and the second portion including a material having a second refractive index different from the first refractive index. 22. The control device of clause 1, wherein the two or more portions of the second prism include a first and a second portion, the first portion including a material having a first refractive index and the second portion including a material having a second refractive index that is the same as the first refractive index. 23. The control device of clause 1, wherein the first prism and the second prism each comprise calcium fluoride or magnesium fluoride. 24. The control device of clause 1, wherein the activation mechanism includes a pneumatic actuator or an electromechanical actuator. 25. A method for controlling the wavelength and bandwidth of a light beam generated by an optical oscillator, the method comprising: selecting a bandwidth range from a set of distinct bandwidth ranges, the selection comprising positioning a distinct portion of a second prism having a plurality of distinct portions at an optical plane through which the light beam passes; controlling the magnification of the light beam generated from the optical oscillator to a desired optical magnification based on the selected bandwidth range, including passing the light beam through separate portions positioned on optical planes of a first prism and a second prism closest to the optical oscillator; adjusting the angle at which the light beam travels, including passing the light beam through at least a third prism; and A method comprising: impinging the light beam from at least a third prism on a dispersive optical element positioned to interact with the light beam in a Littrow configuration; selecting a wavelength and bandwidth of the light beam based on the adjusted angle; and selecting a wavelength and bandwidth of the light beam based on an optical magnification of the light beam impinging on the dispersive optical element. 26. A deep ultraviolet (DUV) laser system comprising a line narrowing module comprising multiple prisms, wherein an incident laser beam from the laser first interacts with a first prism and then interacts with a second prism after the first prism, the second prism comprises two distinct stacked portions including a first portion designed to interact with a higher bandwidth of the incident laser beam and a second portion designed to interact with a lower bandwidth of the incident laser beam; a second prism movable between a first position where the laser beam interacts with the first portion and a second position where the laser beam interacts with the first portion; A deep ultraviolet (DUV) laser system, wherein the second prism is movable by translation using an activation mechanism controlled by a controller to vary the target bandwidth of the laser beam. 27. The DUV laser system of clause 26, wherein the first portion has a first shape and the second portion has a second shape different from the first shape. 28. A DUV laser system according to clause 26, wherein the activation mechanism is a pneumatic or electrical activation mechanism. 29. A light source configured to generate a light beam; a spectral characteristic control device arranged to interact with a light beam produced by the light source, the spectral characteristic control device comprising: a dispersive optical element; a beam expander comprising a plurality of prisms disposed in an optical path between a dispersive optical element and an aperture through which the light beam of the light source can pass, the dispersive optical element and the beam expander being positioned such that the light beam of the light source interacts with the aperture, the prisms, and the dispersive optical element along the optical path; an activation mechanism configured to select a bandwidth range of the light beam by moving a second prism of the beam expander along a direction not parallel to the light path to position a particular geometrically distinct portion of the second prism in the light path, wherein the second prism is positioned adjacent to the first prism closest to the aperture.

[0047]

[0066] These and other embodiments are within the scope of the following claims.

Claims

1. 1. A spectral feature control device comprising: a spectral feature selection module comprising a plurality of prisms disposed at an optical plane and configured to receive and pass an incident light beam along the optical plane, the plurality of prisms comprising: a first prism positioned at an input side of the spectral feature selection module and configured to receive the incident light beam; a second prism configured to receive the light beam exiting the first prism, the second prism comprising two or more portions, each portion configured to allow a distinct bandwidth range of the light beam; and an activation mechanism configured to move the second prism along a direction relative to the optical plane, thereby selecting a bandwidth range of the light beam by positioning a particular portion of the second prism at the optical plane.

2. The control device of claim 1 , wherein the two or more portions are stacked together relative to the optical plane.

3. The control device of claim 1 , wherein the spectral feature selection module is configured to select wavelengths in the deep ultraviolet (DUV) range of the light beam.

4. The control device of claim 1 , further comprising a first actuator configured to rotate the first prism.

5. The control device of claim 4 , wherein rotation of said first prism thereby changes the optical magnification of said light beam.

6. 5. The control device of claim 4, wherein the first actuator is configured to rotate the first prism through a range of angles, and the activation mechanism is configured to move the second prism, thereby adjusting the optical magnification of the light beam in a range of about 10x to about 50x.

7. 7. The control device of claim 6, wherein adjusting the optical magnification of the light beam in a range of about 10x to about 50x thereby adjusts the bandwidth of the light beam in a range of about 1000 femtometers (fm) to about 250 fm.

8. The control device of claim 4 , wherein the first actuator comprises one or more of a motor, a valve, a pressure control device, a piezoelectric device, a linear motor, a hydraulic actuator, and a voice coil.

9. 2. The control device of claim 1, wherein the second prism comprises a first portion stacked on top of a second portion, the first portion configured to interact with a higher bandwidth range of the light beam when positioned at the optical plane, and the second portion configured to interact with a lower bandwidth range of the light beam when positioned at the optical plane.

10. The control device of claim 9 , wherein the first portion has a first geometry and the second portion has a second geometry that is different from the first geometry.

11. 10. The control device of claim 9, wherein positioning the first portion in the optical path enables the optical magnification of the light beam in a range of about 10x to about 19x, and positioning the second portion in the optical path enables the optical magnification of the light beam in a range of about 20x to about 50x.

12. 12. The control device of claim 11, wherein the first portion comprises a first right-angled triangular geometry including one or more dimensions, and the second portion comprises a second right-angled triangular geometry including one or more dimensions different from one or more dimensions of the first right-angled triangular geometry.

13. The control device of claim 10 , wherein the first portion includes a wedge prism with at least one surface plane in the optical path, the surface plane having a uniform, flat geometry.

14. The control device of claim 10 , wherein the first portion includes a wedge prism with at least one surface plane in the optical path, the surface plane having a convex or concave geometry.

15. 3. The control device of claim 2, wherein the activation mechanism configured to move the second prism along a direction relative to the optical plane includes moving the second prism perpendicular to the optical plane to select the bandwidth range of the light beam.

16. The control device of claim 1 , wherein the spectral feature selection module further comprises a third prism and a fourth prism, and a diffractive optical element positioned to interact with the light beam in a Littrow configuration.

17. 17. The control device of claim 16, wherein adjustment of the first and second prisms primarily changes at least the optical magnification of the light beam to enable selection of the bandwidth of the light beam.

18. a third actuator configured to rotate the third prism; a fourth actuator configured to rotate the fourth prism; The control device of claim 17 , wherein the rotation of the third and fourth prisms changes a center wavelength of the light beam.

19. 20. The control device of claim 18, wherein the third prism and the fourth prism each comprise calcium fluoride or magnesium fluoride.

20. 20. The control device of claim 19, wherein the third prism and the fourth prism are right-angled triangular prisms.

21. 2. The control device of claim 1, wherein the two or more portions of the second prism include first and second portions, the first portion including a material having a first refractive index and the second portion including a material having a second refractive index different from the first refractive index.

22. 2. The control device of claim 1, wherein the two or more portions of the second prism include first and second portions, the first portion including a material having a first refractive index and the second portion including a material having a second refractive index that is the same as the first refractive index.

23. The control device of claim 1 , wherein the first prism and the second prism each comprise calcium fluoride or magnesium fluoride.

24. The control device of claim 1 , wherein the activation mechanism comprises a pneumatic actuator or an electromechanical actuator.

25. 1. A method for controlling the wavelength and bandwidth of a light beam generated by an optical oscillator, said method comprising: selecting a bandwidth range from a set of distinct bandwidth ranges, the selection comprising positioning a distinct portion of a second prism comprising a plurality of distinct portions at an optical plane through which the light beam passes; controlling the magnification of the light beam generated from the optical oscillator to a desired optical magnification based on the selected bandwidth range, including passing the light beam through the distinct portions positioned at the optical plane of a first prism closest to the optical oscillator and a second prism; adjusting the angle at which the light beam travels, including passing the light beam through at least a third prism; and selecting the wavelength and bandwidth of the light beam based on the adjusted angle, including impinging the light beam from the at least third prism on a dispersive optical element positioned to interact with the light beam in a Littrow configuration, and selecting the wavelength and bandwidth of the light beam based on the optical magnification of the light beam impinging on the dispersive optical element.

26. 1. A deep ultraviolet (DUV) laser system comprising a line narrowing module comprising a plurality of prisms, wherein an incident laser beam from a laser first interacts with a first prism and then interacts with a second prism after the first prism, the second prism comprises two distinct stacked portions including a first portion designed to interact with a higher bandwidth of the incident laser beam and a second portion designed to interact with a lower bandwidth of the incident laser beam; the second prism is movable between a first position where the laser beam interacts with the first portion and a second position where the laser beam interacts with the first portion; A deep ultraviolet (DUV) laser system, wherein the second prism is movable by translation using an activation mechanism controlled by a controller to vary a target bandwidth of the laser beam.

27. 27. The DUV laser system of claim 26, wherein the first portion has a first shape and the second portion has a second shape that is different from the first shape.

28. 27. The DUV laser system of claim 26, wherein the activation mechanism is a pneumatic or electrical activation mechanism.

29. a light source configured to generate a light beam; a spectral characteristic controller arranged to interact with the light beam produced by the light source, the spectral characteristic controller comprising: a dispersive optical element; a beam expander comprising a plurality of prisms disposed in an optical path between the dispersive optical element and an aperture through which the light beam of the light source can pass, the dispersive optical element and the beam expander being disposed such that the light beam of the light source interacts with the aperture, the prisms, and the dispersive optical element along the optical path; an activation mechanism configured to select a bandwidth range of the light beam by moving a second prism of the beam expander along a direction non-parallel to the optical path to position a particular geometrically distinct portion of the second prism in the optical path, wherein the second prism is positioned adjacent to a first prism closest to the aperture.

Images