Patent Publication Number: US-2023152709-A1

Title: Semiconductor processing tool and methods of operation

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This patent application claims priority to U.S. Provisional Patent Application No. 63/264,057, filed on Nov. 15, 2021, and entitled “SEMICONDUCTOR PROCESSING TOOL AND METHODS OF OPERATION.” The disclosure of the prior application is considered part of and is incorporated by reference into this patent application. 
    
    
     BACKGROUND 
     As semiconductor device sizes continue to shrink, some lithography technologies suffer from optical restrictions, which lead to resolution issues and reduced lithography performance. In comparison, extreme ultraviolet (EUV) lithography can achieve much smaller semiconductor device sizes and/or feature sizes through the use of reflective optics and radiation wavelengths of approximately 13.5 nanometers or less. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. 
         FIG.  1    is a diagram of an example lithography system described herein. 
         FIG.  2    is a diagram of an example implementation described herein. 
         FIG.  3    is a diagram of an example pixel configuration for an illumination system described herein for use in the lithography system of  FIG.  1   . 
         FIGS.  4 - 6    are diagrams of example implementations of pixel types described herein. 
         FIGS.  7 ,  8 A- 8 D, and  9    are diagrams of example implementations of configurable pixels described herein. 
         FIGS.  10 A- 10 C  are diagrams of example pixel configurations for an illumination system described herein for use in the lithography system of  FIG.  1   . 
         FIG.  11    is a diagram of example components of one or more devices of  FIG.  1    described herein. 
         FIGS.  12 - 14    are flowcharts of example processes relating to configuring pixels of an illumination system described herein. 
     
    
    
     DETAILED DESCRIPTION 
     The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. 
     Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly. 
     As pattern sizes continue to decrease in advanced semiconductor fabrication processes, the ability to transfer a high-contrast image patterns onto a semiconductor substrate in a lithography exposure operation becomes more difficult. Numerical aperture sizes may be increased (to 0.55 or greater, as an example) in advanced semiconductor fabrication processes, which may lead to reduced contrast and reduced interference efficiency. This may result in reduced lithography throughput, reduced pattern quality, reduced semiconductor device yield and performance, and/or an increase in semiconductor defects, among other examples. 
     Some implementations described herein provide an illumination system for use in a lithography system (e.g., an EUV lithography system or another type of lithography system) and associated methods of operation. The illumination system includes a plurality of pixels (or spots) that are (or may be) configured in one or more polarization configuration types. In this way, the pixels of the illumination system may be configured to promote particular types of polarization (e.g., transverse electric ( 1 E) polarization, transverse magnetic (TM) polarization) to increase pattern contrast while achieving suitable exposure operation throughput. Moreover, the pixels of the illumination system may be configured to achieve free-form (arbitrary or freely-configurable) polarization, which permits the polarization of radiation to be tailored to particular exposure operation patterns and other parameters. 
       FIG.  1    is a diagram of an embodiment of a lithography system  100  described herein. The lithography system  100  includes an EUV lithography system or another type of lithography system that is configured to transfer a pattern to a semiconductor substrate using mirror-based optics. The lithography system  100  may be configured for use in a semiconductor processing environment such as a semiconductor foundry or a semiconductor fabrication facility. 
     As shown in  FIG.  1   , the lithography system  100  includes the radiation source  102  and an exposure tool  104 . The radiation source  102  (e.g., an EUV radiation source or another type of radiation source) is configured to generate radiation  106  such as EUV radiation and/or another type of electromagnetic radiation (e.g., light, EUV light). The exposure tool  104  (e.g., an EUV scanner or another type of exposure tool) is configured to focus the radiation  106  onto a reflective reticle  108  (or a photomask) such that a pattern is transferred from the reticle  108  onto a semiconductor substrate  110  using the radiation  106 . 
     The radiation source  102  includes a vessel  112  and a collector  114  in the vessel  112 . The collector  114 , includes a curved mirror that is configured to collect the radiation  106  generated by the radiation source  102  and to focus the radiation  106  toward an intermediate focus  116 . The radiation  106  is produced from a plasma that is generated from droplets  118  (e.g., tin (Sn) droplets or another type of droplets) being exposed to a laser beam  120 . The droplets  118  are provided across the front of the collector  114  by a droplet generator (DG) head  122 . The DG head  122  is pressurized to provide a fine and controlled output of the droplets  118 . 
     A laser source, such as a pulse carbon dioxide (CO 2 ) laser, generates the laser beam  120 . The laser beam  120  is provided (e.g., by a beam delivery system to a focus lens) such that the laser beam  120  is focused through a window  124  of the collector  114 . The laser beam  120  is focused onto the droplets  118  which generates the plasma. The plasma produces a plasma emission, some of which is the radiation  106 . The laser beam  120  is pulsed at a timing that is synchronized with the flow of the droplets  118  from the DG head  122 . 
     The exposure tool  104  includes an illuminator  126  and a projection optics box (POB)  128 . The illuminator  126  includes a plurality of reflective mirrors that are configured to focus and/or direct the radiation  106  onto the reticle  108  so as to illuminate the pattern on the reticle  108 . The plurality of mirrors include, for example, a mirror  130   a  and a mirror  130   b  (referred to herein as an illumination system  130   b ). The mirror  130   a  includes a field facet mirror (FFM) or another type of mirror that includes a plurality of field facets. The illumination system  130   b  includes a pupil facet mirror (PFM) or another type of mirror that also includes a plurality of pupil facets, pixels, or illumination spots. As described herein, the pixels of the illumination system  130   b  are arranged (and/or are capable of being configured) to turn on/off, focus, polarize, and/or otherwise tune the radiation  106  from the radiation source  102  to increase or emphasize particular types of radiation components (e.g., transverse electric (TE) polarized radiation, transverse magnetic (TM) polarized radiation). This enables the illumination system  130   b  to increase the uniformity or change the intensity distribution of the radiation  106  and increase the contrast of the pattern of the reticle  108  transferred to the semiconductor substrate  110 . Another mirror  132  (e.g., a relay mirror) is included to direct radiation  106  from the illuminator  126  onto the reticle  108 . 
     The projection optics box  128  includes a plurality of mirrors that are configured to project the radiation  106  onto the semiconductor substrate  110  after the radiation  106  is modified based on the pattern of the reticle  108 . The plurality of reflective mirrors include, for example, mirrors  134   a - 134   f . In some implementations, the mirrors  134   a - 134   f  are configured to focus or reduce the radiation  106  into an exposure field, which may include one or more die areas on the semiconductor substrate  110 . 
     The exposure tool  104  includes a substrate stage  136  (e.g., a wafer stage) configured to support the semiconductor substrate  110 . Moreover, the substrate stage  136  is configured to move (or step) the semiconductor substrate  110  through a plurality of exposure fields as the radiation  106  transfers the pattern from the reticle  108  onto the semiconductor substrate  110 . The exposure tool  104  also includes a reticle stage  138  that configured to support and/or secure the reticle  108 . Moreover, the reticle stage  138  is configured to move or slide the reticle through the radiation  106  such that the reticle  108  is scanned by the radiation  106 . In this way, a pattern that is larger than the field or beam of the radiation  106  may be transferred to the semiconductor substrate  110 . A controller  140  included in the lithography system  100  (e.g., in the exposure tool  104  or another component of the lithography system  100 ) is configured to communicate with and/or control actions of various components and/or subsystems of the lithography system  100 , including the radiation source  102  and/or the exposure tool  104 , among other examples. In some implementations, the controller  140  transmits signals to the lithography system  100  and/or the components thereof (e.g., the radiation source  102 , the exposure tool  104 ) to cause the lithography system  100  and/or the components thereof (e.g., the radiation source  102 , the exposure tool  104 ) to perform an exposure operation. 
     In an example exposure operation (e.g., an EUV exposure operation), the DG head  122  provides the stream of the droplets  118  across the front of the collector  114 . The laser beam  120  contacts the droplets  118 , which causes a plasma to be generated. The plasma emits or produces the radiation  106  (e.g., EUV light). The radiation  106  is collected by the collector  114  and directed out of the vessel  112  and into the exposure tool  104  toward the mirror  130   a  of the illuminator  126 . The mirror  130   a  reflects the radiation  106  onto the illumination system  130   b , which reflects the radiation  106  onto the mirror  132  toward the reticle  108 . The radiation  106  is modified by the pattern in the reticle  108 . In other words, the radiation  106  reflects off of the reticle  108  based on the pattern of the reticle  108 . The reflective reticle  108  directs the radiation  106  toward the mirror  134   a  in the projection optics box  128 , which reflects the radiation  106  onto the mirror  134   b . The radiation  106  continues to be reflected and reduced in the projection optics box  128  by the mirrors  134   c - 134   f . The mirror  134   f  reflects the radiation  106  onto the semiconductor substrate  110  such that the pattern of the reticle  108  is transferred to the semiconductor substrate  110 . The above-described exposure operation is an example, and the lithography system  100  may operate according to other EUV techniques and radiation paths that include a greater quantity of mirrors, a lesser quantity of mirrors, and/or a different configuration of mirrors. 
     As indicated above,  FIG.  1    is provided as an example. Other examples may differ from what is described with regard to  FIG.  1   . 
       FIG.  2    is a diagram of an example implementation  200  described herein. The example implementation  200  includes an example operation of the mirror  130   a  and the illumination system  130   b . As shown in  FIG.  2   , the mirror  130   a  includes a plurality of mirror facets  202 . The mirror facets  202  may include rectangular-shaped mirror facets, square-shaped mirror facets, and/or may include another shape of mirror facets. The mirror facets  202  are configured to receive the radiation  106  and split the radiation  106  into individual or separate beams of radiation. In this way, the mirror facets  202  are configured to tune, modify, or adjust the radiation  106 . 
     As further shown in  FIG.  2   , the illumination system  130   b  includes a plurality of pixels  204  on a substrate  206 . The pixels  204  include various components described herein, including mirrors, polarizers, and/or actuators, among other examples. The pixels  204  are configured to receive the beams of radiation from the mirror facets  202  and reflect (or redirect) the beams of radiation toward the reticle  108  (or other intervening mirrors). In some implementations, the pixels  204  include approximately circle-shaped structures that are arranged in a grid pattern or another pattern on the substrate  206 . In some implementations, the pixels  204  include microelectromechanical systems (MEMS) that include the mirrors, polarizers, and/or actuators, described herein. In these implementations the MEMS of the pixels  204  (and the mirrors, polarizers, and/or actuators, described herein) may be formed by various MEMS fabrication and/or processing techniques. 
     In some implementations, the mirror  130   a  includes on the order of hundreds of mirror facets  202 . For examples, the mirror  130   a  may include 300 or more mirror facets  202  or another quantity of mirror facets  202 . In some implementations, the illumination system  130   b  includes on the order of thousands of pixels  204  or more. For examples, the illumination system  130   b  may include 1000 or more pixels  204  or another quantity of pixels  204 . In some implementations, a subset of the mirror facets  202  and a subset of the pixels  204  are activated in an exposure operation of the lithography system  100 . 
     As further shown in  FIG.  2   , the radiation  106  may be directed from the intermediate focus  116  and toward the mirror  130   a  (e.g., by the radiation source  102 ). The radiation  106  incident upon the mirror  130   a  (or a portion thereof) is reflected off the mirror facets  202 . The reflected radiation  208  is directed toward the pixels  204  of the illumination system  130   b  as a plurality of beams. Each respective beam of the reflected radiation  208  is incident upon one or more pixels  204  of the illumination system  130   b . Radiation in reflected off the pixels  204  and toward the reticle  108  (or other intervening mirrors). In some implementations, the reflected radiation  208  includes unpolarized EUV radiation, and the pixels  204  are configured to modify the unpolarized EUV radiation in various ways including polarizing the unpolarized EUV radiation. Thus, the EUV radiation reflected by the pixels  204  may include TE polarized EUV radiation, TM polarized EUV radiation, unpolarized EUV radiation, or a combination thereof. 
     As indicated above,  FIG.  2    is provided as an example. Other examples may differ from what is described with regard to  FIG.  2   . 
       FIG.  3    is a diagram of an example implementation  300 . The example implementation  300  illustrates a plurality of polarization configurations for the pixels  204  of the illumination system  130   b  described herein for use in the lithography system of  FIG.  1   . As shown in  FIG.  3   , the pixels  204  are arranged in a grid pattern on the substrate  206 . However, the pixels  204  may be arranged in another pattern, such as a staggered pattern (e.g., a brick pattern), an asymmetric pattern, a non-uniform pattern, and/or another type of pattern. 
     As further shown in  FIG.  3   , the pixels  204  are configured to reflect a particular type of radiation (e.g., EUV radiation). In particular, a pixel  204  may be configured as an unpolarized pixel  302  (e.g., in an unpolarized polarization configuration), a TE polarized pixel  304  (e.g., in a TE polarized polarization configuration), or a TM polarized pixel  306  (e.g., in a TM polarized polarization configuration). In some implementations, a pixel  204  may be configured as a plurality of polarization types (e.g., TE polarization and TM polarization), as described herein. 
     An unpolarized pixel  302  includes a pixel  204  that is configured to reflect unpolarized radiation (e.g., unpolarized EUV radiation). Unpolarized pixels  302  may be capable of reflecting a greater intensity of EUV radiation relative to polarized pixels, which enables the unpolarized pixels  302  to increase the throughput of the exposure tool  104 . The arrows of the unpolarized pixels  302  represent the non-specific and non-directional attributes of the unpolarized radiation. 
     A TE polarized pixel  304  includes a pixel  204  that is configured to reflect TE polarized radiation (e.g., TE polarized EUV radiation). TE polarized radiation refers to electromagnetic radiation (or light) in which the electric field of the electromagnetic radiation is normal (or perpendicular) to the plane of incidence of the electromagnetic radiation, and in which the magnetic field of the electromagnetic radiation is along (or parallel to) the plane of incidence. TE polarized pixels  304  may reflect EUV radiation at a lower intensity relative to an unpolarized pixel  302  because the TE polarized radiation is only one component of unpolarized radiation—the other component being TM polarized radiation. However, TE polarized radiation may increase the contrast of a pattern transferred from the reticle  108  to the semiconductor substrate  110  by the reflected radiation (particularly at higher numerical apertures). The increased contrast is provided by the complete (or near complete) destruction interference of the TE polarized radiation, which results in a final electric vector of 0 at the semiconductor substrate  110 . In other words, the TE polarized radiation is brighter (e.g., greater intensity) in the constructive interference of the TE polarized radiation and darker (or completely dark) in the deconstructive interference of the TE polarized radiation. 
     A TM polarized pixel  306  includes a pixel  204  that is configured to reflect TM polarized radiation (e.g., TM polarized EUV radiation). TM polarized radiation refers to electromagnetic radiation (or light) in which the electric field of the electromagnetic radiation is along (or parallel to) to the plane of incidence of the electromagnetic radiation, and in which the magnetic field of the electromagnetic radiation is normal (or perpendicular) the plane of incidence. 
     The pixels  204  may be configured in various combinations and/or arrangements of polarization configurations to achieve particular types of polarization patterns for the illumination system  130   b . For example, the pixels  204  of the illumination  130   b  may include a combination of unpolarized pixels  302 , TE polarized pixels  304 , and TM polarized pixels  306  to achieve a radial polarization pattern or an azimuthal polarization pattern, among other examples. Moreover, in some implementations, one or more of the pixels  204  are configurable in that one or more of the pixels  204  are capable of switching between various polarization configurations, which enables free-form or arbitrary polarization of EUV radiation in the exposure tool  104 . In other words, this provides the exposure tool  104  (and the controller  140 ) with the flexibility to optimize polarization patterns for different exposure operations, different pattern configurations of reticles  108  used in the exposure tool  104 . The quantity of unpolarized pixels  302  included on the substrate  206  may be increased to increase the reflectivity of the illumination system  130   b  and to increase the throughput of the exposure tool  104 , or may be decreased to enable a greater quantity of TE polarized pixels  304  and/or a greater quantity of TM polarized pixels  306  to be included on the substrate  206 . The quantity of TE polarized pixels  304  may be increased to increase the contrast of the pattern transferred from the reticle  108  to the semiconductor substrate  110 , or may be decreased to enable a great quantity of unpolarized pixels  302  and/or a greater quantity of TM polarized pixels  306  to be included on the substrate  206 . The quantity of TM polarized pixels  306  may be increased to enable flexibility in configuring particular types of polarization patterns, or may be decreased to enable a great quantity of unpolarized pixels  302  and/or a greater quantity of TE polarized pixels  304  to be included on the substrate  206 . 
     As indicated above,  FIG.  3    is provided as an example. Other examples may differ from what is described with regard to  FIG.  3   . 
       FIG.  4    is a side view diagram of an example implementation  400  of an unpolarized pixel  302  described herein. In particular, the example implementation  400  illustrates the structure of the unpolarized pixel  302  and the operation of the unpolarized pixel  302 . 
     As shown in  FIG.  4   , the unpolarized pixel  302  includes a multilayer mirror (ML mirror)  402 . The multilayer mirror  402  may physically occupy the entire approximate area of the unpolarized pixel  302  or a portion thereof. The multilayer mirror  402  includes a base layer  404  and a plurality of alternating layers over and/or on the base layer  404 . The alternating layers include a plurality of layers  406  and a plurality of layers  408 , where a layer  406  is included over and/or on the base layer  404 , a layer  408  is included over and/or on the layer  406 , another layer  406  is included over and/or on the layer  408 , another layer  408  is included over and/or on the other layer  406 , and so on. In some implementations, the layers  406  and  408  are formed as a coating on the base layer  404 . In some implementations, the layers  406  and  408  are formed as a separate structure that is subsequently bonded to the base layer  404 . 
     The layers  406  and  408  include alternating layers of molybdenum and silicon (Mo/Si layers), molybdenum and beryllium (Mo/Be layers), or another combination of layers that have different refractive indices. The combination of the materials in the layers  406  and  408  may be selected to provide a difference in refractive indices between the layers  406  and  408  (e.g., to provide reflectivity at an interface of the layers  406  and  408  according to Fresnel&#39;s equations), while reducing and/or minimizing extinction coefficients for the layers  406  and  408  (e.g., to minimize absorption). 
     In general, the reflectivity of the multilayer mirror  402  may increase as a quantity of pairs of the layers  406  and  408  is increased. In some implementations, the multilayer mirror  402  includes 20 to 40 pairs of the layers  406  and  408 , which enables the multilayer mirror  402  to achieve a reflectivity of approximately 60% to approximately 80%. However, other quantities of pairs of the layers  406  and  408  are within the scope of the present disclosure. A thickness of the silicon layers (e.g., the layers  408 ) may be included in a range of approximately 2 nanometers (nm) to about 6 nm, and a thickness of the molybdenum layers (e.g., the layers  406 ) may be included in a range of approximately 1 nm to approximately 5 nm to achieve suitable reflectivity and absorption performance. However, other values for the thickness of the layers  406  and  408  are within the scope of the present disclosure. 
     As further shown in  FIG.  4   , unpolarized radiation  208  (e.g., unpolarized EUV radiation reflected by the mirror facets  202  from the mirror  130   a  toward the illumination system  130   b ) incident upon the multilayer mirror  402  of the unpolarized pixel  302  is reflected as reflected unpolarized radiation (e.g., reflected unpolarized EUV radiation)  410  by the multilayer mirror  402 . It is noted that the  FIG.  4    illustrates the direction of travel of the unpolarized radiation  208  (e.g., a light path of the unpolarized radiation  208 ) and a direction of travel of the reflected unpolarized radiation  410  (e.g., a light path of the reflected unpolarized radiation  410 ). In practice, the unpolarized radiation  208  may illuminate approximately the entire surface area of the multilayer mirror  402 , and the reflected unpolarized radiation  410  may be reflected off approximately the entire surface area of the multilayer mirror  402 . Moreover, portions of the reflected unpolarized radiation  410  may be reflected off one or more of the layers  406  and/or  408  further down from the top surface of the multilayer mirror  402 . 
     The overall angle  412  between a ray of the unpolarized radiation  208  incident upon the multilayer mirror  402  and a ray of a corresponding reflected unpolarized radiation  410  may be referred to as a chief ray angle (CRA) or as a chief ray angle at object (CRAO). The overall angle  412  may be approximately 8 degrees to approximately 16 degrees or another angle. The overall angle  412  may include the sum of the angle of incidence  414   a  of the ray of the unpolarized radiation  208  and the angle of reflectance  414   b  of the ray of the reflected unpolarized radiation  410 . The magnitude of the angle of incidence  414   a  and the magnitude of the angle of reflectance  414   b  are relative to an axis  416  that is approximately perpendicular to the surface of reflection of the multilayer mirror  402 . In some implementations, the magnitude of the angle of incidence  414   a  and the magnitude of the angle of reflectance  414   b  are each approximately 4 to approximately 8 degrees. However, other values for the magnitude of the angle of incidence  414   a  and the magnitude of the angle of reflectance  414   b  are within the scope of the present disclosure. 
     Note that TE and TM modes are defined relative to the plane of incidence in all examples in the present disclosure. In  FIG.  4   , for example, the incident beam  208  comes from left side with incident angle  414   a  to the axis  416 . Therefore, the electric field is in the Y direction for the TE polarized pixel  304 . The electric field is in the X direction for the TM polarized pixel  306 . The TE and TM mode are different when considering the imaging on a wafer with certain orientation of a particular pattern. For periodic line and space array in the Y direction, the TE mode is the one with electric field in the Y direction, as in the TE polarized pixel  304  in  FIG.  3   , and the TM mode is with electric field in the X direction, as in the TM polarized pixel  306  in  FIG.  3   . For periodic line and space array in X direction, the TE mode is with the electric field in the X direction, and the TM mode is with the electric field in the Y direction. 
     Fig. As indicated above,  FIG.  4    is provided as an example. Other examples may differ from what is described with regard to  FIG.  4   . 
       5  is a side view diagram of an example implementation  500  of a TE polarized pixel  304  described herein. In particular, the example implementation  500  illustrates the structure of the TE polarized pixel  304  and the operation of the TE polarized pixel  304 . 
     As shown in  FIG.  5   , the TE polarized pixel  304  includes a multilayer mirror  402  as described above in connection with  FIG.  4   . Moreover, the TE polarized pixel  304  includes a multilayer polarizer (e.g., an ML polarizer structure)  502 . The multilayer polarizer  502  includes a plurality of alternating layers, including a plurality of layers  504  and a plurality of layers  506 , where a layer  506  is included over and/or on a layer  504 , another layer  504  is included over and/or on the layer  506 , another layer  506  is included over and/or on the other layer  504 , and so on. 
     The layers  504  and  506  include alternating layers of molybdenum and silicon (Mo/Si layers), molybdenum and beryllium (Mo/Be layers), or another combination of layers that have different refractive indices. The combination of the materials in the layers  504  and  506  may be selected to provide a difference in refractive indices between the layers  504  and  506  (e.g., to provide reflectivity at an interface of the layers  504  and  506  according to Fresnel&#39;s equations), while providing reducing and/or minimizing extinction coefficients for the layers  504  and  506  (e.g., to minimize absorption). The quantity of pairs including a layer  504  and a layer  506  may be included in a range of 18 pairs to 22 pairs to provide sufficient reflectivity and sufficient polarization. However, other values for the quantity of the pairs are within the scope of the present disclosure. 
     The thickness of a layer  504  and the thickness of a layer  506  may be different to achieve polarization of the unpolarized radiation  208  incident upon the multilayer polarizer  502 . In particular, the difference in the respective thicknesses of the layers  504  and the layers  506  facilitate the separation of the unpolarized radiation  208  into reflected TE polarized radiation  508  and transmitted TM polarized radiation. In particular, the reflected TE polarized radiation  508  is reflected off of the multilayer polarizer  502  and toward the multilayer mirror  402 , whereas the transmitted TM polarized radiation is transmitted through the multilayer polarizer  502  (e.g., and is not reflected by the TE polarized pixel  304 ). In some implementations, the thickness of the layers  504  (e.g., which may include molybdenum layers) are included in a range of approximately 2.2 nm to approximately 2.8 nm, whereas the thickness of the layers  506  (e.g., which may include silicon layers) are included in a range of approximately 6.7 nm to approximately 7.3 nm to achieve a sufficient reflectance degree of polarization (DOP) and to achieve a sufficient transmittance degree of polarization. However, other values for the thicknesses of the layers  504  and  506  are within the scope of the present disclosure. 
     As further shown in  FIG.  5   , the unpolarized radiation  208  incident upon the multilayer polarizer  502  of the TE polarized pixel  304  is reflected as reflected TE polarized radiation (e.g., reflected TE polarized EUV radiation)  508  by the multilayer polarizer  502  toward the multilayer mirror  402 . It is noted that the  FIG.  5    illustrates the direction of travel of the unpolarized radiation  208  (e.g., a light path of the unpolarized radiation  208 ) and a direction of travel of the reflected TE polarized radiation  508  (e.g., a light path of the reflected TE polarized radiation  508 ). In practice, the unpolarized radiation  208  may illuminate approximately the entire surface area of the multilayer polarizer  502 , and the reflected TE polarized radiation  508  may be reflected onto approximately the entire surface area of the multilayer mirror  402  (or a portion thereof). Moreover, portions of the reflected TE polarized radiation  508  may be reflected off of one or more of the layers  504  and/or  506  further down from the top surface of the multilayer polarizer  502 , and may be reflected off of one or more of the layers  406  and/or  408  further down from the top surface of the multilayer mirror  402 . 
     The overall angle  510  between a ray of the unpolarized radiation  208  incident upon the multilayer polarizer  502  and a ray of a corresponding reflected TE polarized radiation  508  may be approximately 8 degrees to approximately 16 degrees or another angle. The magnitude of the angle of incidence  512   a  of the unpolarized radiation  208  toward the multilayer polarizer  502  relative to an axis  514  that is approximately perpendicular to the surface of reflection of the multilayer polarizer  502 , and the magnitude of the angle of reflectance  512   b  of the reflected TE polarized radiation  508  reflected off of the multilayer polarizer  502 , may each be included in a range of approximately 40 degrees to approximately 44 degrees to achieve a high reflectance degree of polarization (e.g., approximately 99% reflectance degree of polarization or greater). However, other values for the magnitude of the angle of incidence  512   a  and the magnitude of the angle of reflectance  512   b  are within the scope of the present disclosure. 
     The magnitude of the angle of incidence  516   a  of the reflected TE polarized radiation  508  incident upon the multilayer mirror  402  relative to an axis  518  that is approximately perpendicular to the surface of reflection of the multilayer mirror  402 , and the magnitude of the angle of reflectance  516   b  of the reflected TE polarized radiation  508  reflected off of the multilayer mirror  402 , may each be included in a range of approximately 52 degrees to approximately 56 degrees to achieve a particular chief ray angle (e.g., the overall angle  510 ) for the TE polarized pixel  304 . However, other values for the magnitude of the angle of incidence  512   a  and the magnitude of the angle of reflectance  512   b  are within the scope of the present disclosure. The chief ray angle may include the difference between the angle of reflectance  516   b  and the angle of incidence  512   a . As an example, the chief ray angle may be approximately 12 degrees for a 42 degree angle of incidence  512   a  and a 54 degree angle of reflectance  516   b . However, other values for the chief ray angle of the TE polarized pixel  304  are within the scope of the present disclosure. 
     In some implementations, a combination of the parameters described above for the multilayer polarizer  502 , such as the quantity of alternating pairs of the layers  504  and  506 , the differences in thicknesses between the layers  504  and  506 , and the angle of incidence  512   a  of the unpolarized radiation  208  toward the multilayer polarizer  502  may be configured to achieve or provide particular performance parameters for multilayer polarizer  502 . For example, a combination of the parameters for the multilayer polarizer  502  may be configured in one or more of the ranges described above (and/or other ranges) to achieve a reflectivity of TM polarized radiation of approximately 0.01% or less and a reflectivity of the TE polarized radiation of approximately 34% or greater. As another example, a combination of the parameters for the multilayer polarizer  502  may be configured in one or more of the ranges described above (and/or other ranges) to achieve a reflectance degree of polarization of approximately 99% or greater. 
     As further shown in  FIG.  5   , the multilayer polarizer  502  may be positioned lower than the multilayer mirror  402  in the TE polarized pixel  304 . For example, the highest edge (or corner) of the multilayer polarizer  502  may be lower than the highest edge (or corner) of the multilayer mirror  402 , and/or the lowest edge (or corner) of the multilayer polarizer  502  may be lower than the lowest edge (or corner) of the multilayer mirror  402 . The lower relative position of the multilayer polarizer  502  enables the angle of incidence  512   a  to be configured to achieve a high reflectance degree of polarization while enabling the angle of reflectance  516   b  to be configured to achieve a particular chief ray angle for the TE polarized pixel  304 . 
     As indicated above,  FIG.  5    is provided as an example. Other examples may differ from what is described with regard to  FIG.  5   . 
       FIG.  6    is a diagram of an example implementation  600  of a TM polarized pixel  306  described herein. In particular, the example implementation  600  illustrates the structure of the TM polarized pixel  306  and the operation of the TM polarized pixel  306 . 
     As shown in  FIG.  6   , the TM polarized pixel  306  includes a multilayer mirror  402  as described above in connection with  FIG.  4   . Moreover, the TM polarized pixel  306  includes a multilayer polarizer  502  as described above in connection with  FIG.  5   . 
     As further shown in  FIG.  6   , the multilayer polarizer  502  separates and/or extracts TM polarized radiation from unpolarized radiation  208  incident upon the multilayer polarizer  502 . In other words, the multilayer structure of the multilayer polarizer  502  separates the unpolarized radiation  208  into TE polarized radiation (not shown) and the TM polarized radiation, which passes through the multilayer polarizer  502  and is transmitted toward the multilayer mirror  402  as transmitted TM polarized radiation  602   a . The multilayer mirror  402  is positioned below and/or under the multilayer polarizer  502  to receive the transmitted TM polarized radiation  602   a . The multilayer mirror  402  reflects the transmitted TM polarized radiation  602   a  as reflected TM polarized radiation  602   b.    
     It is noted that the  FIG.  6    illustrates the direction of travel of the unpolarized radiation  208  (e.g., a light path of the unpolarized radiation  208 ), a direction of travel of the transmitted TM polarized radiation  602   a  (e.g., a light path of the transmitted TM polarized radiation  602   a ), and a direction of travel of the reflected TM polarized radiation  602   b  (e.g., a light path of the reflected TM polarized radiation  602   b ). In practice, the unpolarized radiation  208  may illuminate approximately the entire surface area of the multilayer polarizer  502 , and the transmitted TM polarized radiation  602   a  may be transmitted onto approximately the entire surface area of the multilayer mirror  402  (or a portion thereof). Moreover, portions of the reflected TM polarized radiation  602   b  may be reflected off one or more of the layers  406  and/or  408  further down from the top surface of the multilayer mirror  402 . 
     The overall angle  604  between a ray of the unpolarized radiation  208  incident upon the multilayer polarizer  502  and a ray of a corresponding reflected TM polarized radiation  602   b  may be approximately 8 degrees to approximately 16 degrees or another angle. The magnitude of the angle of incidence  606  of the unpolarized radiation  208  toward the multilayer polarizer  502  relative to an axis  608  that is approximately perpendicular to the surface of reflection of the multilayer polarizer  502  may be included in a range of approximately 40 degrees to approximately 44 degrees to achieve a high transmission degree of polarization (e.g., approximately 85% transmittance degree of polarization or greater) and to achieve a high degree of transmittance (e.g., approximately 25% or greater). However, other values for the magnitude of the angle of incidence  606  are within the scope of the present disclosure. 
     The magnitude of the angle of incidence  610   a  of the transmitted TM polarized radiation  602   a  and the magnitude of the angle of reflectance  610   b  of the reflected TM polarized radiation  602   b  are relative to an axis  612  that is approximately perpendicular to the surface of reflection of the multilayer mirror  402 . In some implementations, the magnitude of the angle of incidence  610   a  and the magnitude of the angle of reflectance  610   b  are each approximately 4 to approximately 8 degrees. However, other values for the magnitude of the angle of incidence  610   a  and the magnitude of the angle of reflectance  610   b  are within the scope of the present disclosure. 
     In some implementations, a combination of the parameters described above for the multilayer polarizer  502 , such as the quantity of alternating pairs of the layers  504  and  506 , the differences in thicknesses between the layers  504  and  506 , and the angle of incidence  606  of the unpolarized radiation  208  toward the multilayer polarizer  502  may be configured to achieve or provide particular performance parameters for multilayer polarizer  502 . For example, a combination of the parameters for the multilayer polarizer  502  may be configured in one or more of the ranges described above (and/or other ranges) to achieve a reflectivity of TM polarized radiation of approximately 23% or greater and a transmittance of the TM polarized radiation of approximately 2% or less. As another example, a combination of the parameters for the multilayer polarizer  502  may be configured in one or more of the ranges described above (and/or other ranges) to achieve a transmittance degree of polarization of approximately 85% or greater. 
     As indicated above,  FIG.  6    is provided as an example. Other examples may differ from what is described with regard to  FIG.  6   . 
       FIG.  7    is a diagram of an example implementation  700  of a configurable pixel  702  described herein. The example pixel configurations described above in connection with  FIGS.  4 - 6    may be referred to as fixed pixel configurations in that a pixel  204  is configured in one of the pixel configurations described above in connection with  FIGS.  4 - 6    and is not changed. As an example, a pixel  204  may be configured as an unpolarized pixel  302  as illustrated and described above in connection with  FIG.  4   , where the configuration of the pixel  204  does not change from the configuration as an unpolarized pixel  302 . As another example, a pixel  204  may be configured as a TE polarized pixel  304  as illustrated and described above in connection with  FIG.  5   , where the configuration of the pixel  204  does not change from the configuration as a TE polarized pixel  304 . As another example, a pixel  204  may be configured as a TM polarized pixel  306  as illustrated and described above in connection with  FIG.  6   , where the configuration of the pixel  204  does not change from the configuration as a TM polarized pixel  306 . The configurable pixel  702  illustrated in  FIG.  7    is configurable in that the polarization configuration of the configurable pixel  702  is capable of being selectively changed to different polarization configurations, as described herein. The capability to change polarization configuration for configurable pixels  702  on the illumination system  130   b  enables free-form polarization for the exposure tool  104 . Moreover, the configurable pixel  702  is capable of reflecting separated types of polarized radiation (e.g., at the same time), including TE polarized radiation and TM polarized radiation. 
     The configurable pixel  702  (or a plurality of configurable pixels  702 ) may be included on the substrate  206  of the illumination system  130   b  (e.g., as pixel(s)  204 ). In some implementations, the illumination system  130   b  includes all configurable pixels  702 , which increases the flexibility of the illumination system  130   b  to provide free-form polarization. In some implementations, the illumination system  130   b  includes a combination of configurable pixels  702  and fixed pixels (e.g., pixels  204  that are each fixed in one of the polarization configurations illustrated in  FIGS.  4 - 6   ) to provide a degree of free-form polarization while reducing the manufacturing complexity of the illumination system  130   b.    
     As shown in  FIG.  7   , the configurable pixel  702  includes a multilayer polarizer  502  and a plurality of multilayer mirrors  402 , including a multilayer mirror  402   a  under and/or below the multilayer polarizer  502  and another multilayer mirror  402   b  adjacent to the multilayer polarizer  502 . The multilayer polarizer  502  may receive unpolarized radiation  208 , may separate the unpolarized radiation  208  (e.g., using the plurality of pairs of alternating layers  504  and  506 ) into transmitted TM polarized radiation  704   a  and reflected TE polarized radiation  706 . The transmitted TM polarized radiation  704   a  is reflected off the multilayer mirror  402   a , which provides reflected TM polarized radiation  704   b . The reflected TE polarized radiation  706  is reflected off the multilayer mirror  402   b , which reflects the TE polarized radiation  706 . In the example implementation  700  illustrated in  FIG.  7   , the configurable pixel  702  is configured in a polarization configuration in which the configurable pixel  702  reflects the reflected TM polarized radiation  704   a  in a first portion of the configurable pixel  702  and reflects the reflected TE polarized radiation  706  in a second (adjacent) portion of the configurable pixel  702 . 
     The overall angle  708  may correspond to the overall angle  604 . The overall angle  710  may correspond to the overall angle  510 . The angle of incidence  712   a  relative to the axis  714  may correspond to the angle of incidence  512   a  and/or the angle of incidence  606 . The angle of reflectance  712   b  relative to the axis  714  may correspond to the angle of reflectance  512   b . The angle of incidence  716   a  relative to the axis  718  may correspond to the angle of incidence  414   a  and/or the angle of incidence  610   a . The angle of reflectance  716   b  relative to the axis  718  may correspond to the angle of reflectance  414   b  and/or the angle of reflectance  610   b . The angle of incidence  720   a  relative to the axis  722  may correspond to the angle of incidence  516   a . The angle of reflectance  720   b  relative to the axis  722  may correspond to the angle of reflectance  516   b.    
     As further shown in  FIG.  7   , the multilayer polarizer  502 , the multilayer mirror  402   a , and the multilayer mirror  402   b  may each include a respective actuator such that the multilayer polarizer  502 , the multilayer mirror  402   a , and the multilayer mirror  402   b  may be independently actuated to change the polarization configuration of the configurable pixel  702 . For example, the multilayer polarizer  502  includes an actuator  724   a , the multilayer mirror  402   a  includes an actuator  724   b , and the multilayer mirror  402   b  includes an actuator  724   c . The actuators  724   a - 724   c  may include a servo-controlled motor, a direct current (DC) brushed or brushless motor, a linear motor, a stepper motor, and/or another type of actuator that is capable of rotating, translating, and/or displacing the multilayer polarizer  502 , the multilayer mirror  402   a , and/or the multilayer mirror  402   b.    
     The controller  140  may communicate with the actuators  724   a - 724   c  to receive sensor data associated with the multilayer polarizer  502 , the multilayer mirror  402   a , and/or the multilayer mirror  402   b . The sensor data may include or may indicate, for example, position information associated with the multilayer polarizer  502 , the multilayer mirror  402   a , and/or the multilayer mirror  402   b , rotational velocity and/or linear velocity of the multilayer polarizer  502 , the multilayer mirror  402   a , and/or the multilayer mirror  402   b , and/or other types of sensor data. The controller  140  is further configured to communicate with the actuators  724   a - 724   c  to provide one or more signals to the actuators  724   a - 724   c  to selectively configure the configurable pixel  702  in various polarization configurations described herein. The signal(s) may include analog signals (e.g., a voltage, a current), digital signals (e.g., digital communications), and/or other types of signals that are transmitted over a wired and/or wireless connection to the actuators  724   a - 724   c . The controller  140  may provide or transmit a signal to the actuator  724   a  to cause the actuator  724   a  to actuate the multilayer polarizer  502  to cause the configurable pixel  702  to be configured in a particular polarization configuration. The controller  140  may provide or transmit a signal to the actuator  724   b  to cause the actuator  724   b  to actuate the multilayer mirror  402   a  to cause the configurable pixel  702  to be configured in a particular polarization configuration. The controller  140  may provide or transmit a signal to the actuator  724   c  to cause the actuator  724   c  to actuate the multilayer mirror  402   b  to cause the configurable pixel  702  to be configured in a particular polarization configuration. 
     In some implementations, the controller  140  provides or transmits signals to one or more actuators of a plurality of configurable pixels  702  included on the illumination system  130   b  to cause the illumination system  130   b  to be configured in a particular polarization pattern or to enable free-form polarization. In some implementations, the controller  140  provides or transmits signals to one or more actuators of a plurality of configurable pixels  702  to cause subsets of the plurality of configurable pixels  702  to be configured in respective pixel configurations. For example, the controller  140  may provide or transmit a first signal (or a first set of signals) to cause a first subset of configurable pixels  702  to be configured in a TE polarized configuration (e.g., as illustrated and described in connection with  FIG.  8 B ), may provide or transmit a second signal (or a second set of signals) to cause a second subset of configurable pixels  702  to be configured in a TM polarized configuration (e.g., as illustrated and described in connection with  FIG.  8 C ), and may provide or transmit a third signal (or a third set of signals) to cause a third subset of configurable pixels  702  to be configured in an unpolarized configuration (e.g., as illustrated and described in connection with  FIG.  8 A ). Additionally and/or alternatively, the controller  140  may provide or transmit a signal (or a set of signals) to cause a subset of configurable pixels  702  to be configured in the TE polarized and TM polarized configuration illustrated in  FIG.  7   . In some implementations, the controller  140  provides or transmits a signal (or a set of signals) to cause a subset of configurable pixels  702  to be configured in an off configuration (e.g., as illustrated and described in connection with  FIG.  8 D ) such that the subset of configurable pixels  702  is deactivated (e.g., does not reflect incident light). 
     In some implementations, the controller  140  determines the polarization pattern for the illumination system  130   b  (or determines the specific combination of polarization configurations for the plurality of configurable pixels  702 ) based on one or more parameters. The one or more parameters may be associated with an exposure operation of the semiconductor substrate  110  or may be associated with a substrate lot including a plurality of semiconductor substrates  110  that are to be processed in similar exposure operations. The one or more parameters may include, for example, the pattern of the reticle  108  that is to be transferred to the semiconductor substrate  110  (or the substrate lot), a contrast parameter for the exposure operation, a throughput parameter for the exposure operation, and/or other parameters. 
     In some implementations, the controller  140  determines the polarization pattern for the illumination system  130   b  (or determines the specific combination of polarization configurations for the plurality of configurable pixels  702 ) using a machine learning model. The machine learning model may be trained on training data, which may include the specific combinations of polarization configurations for the plurality of configurable pixels  702  from a plurality of historical exposure operations (e.g., thousands of historical exposure operations or more), the throughput and/or contrast achieved for the historical exposure operations, the types of reticles  108  used for the historical exposure operations, and/or other types of parameters for the historical exposure operations. In some implementations, the controller  140  provides the desired outcomes for an exposure operation (e.g., the contrast parameter, the throughput parameters) along with the pattern of the reticle  108  that is to be used in the exposure operation, and the controller  140  uses the machine learning model to analyze combinations of polarization configurations for the plurality of configurable pixels  702  based on the training data to identify a specific combination of polarization configurations for the plurality of configurable pixels  702  that are estimated to achieve the desired outcomes for the exposure operation. In some implementations, the controller  140  provides a candidate combination of polarization configurations for the plurality of configurable pixels  702  for an exposure operation along with the pattern of the reticle  108  that is to be used in the exposure operation, and the controller  140  uses the machine learning model to generate a likelihood or confidence that the candidate combination of polarization configurations for the plurality of configurable pixels  702  will achieve the desired outcomes for an exposure operation (e.g., the contrast parameter, the throughput parameters). 
     In some implementations, the controller  140  determines the polarization configurations for the plurality of configurable pixels  702  prior to an exposure operation and transmits signals to cause the plurality of configurable pixels  702  to be configured in the polarization configurations prior to the exposure operation. Alternatively, or after the start of the exposure operation, the controller  140  may determine modified polarization configurations for one or more of the plurality of configurable pixels  702  during the exposure operation and transmit signals to cause the one or more configurable pixels  702  to be configured in the polarization configurations during the exposure operation. This “on-the-fly” polarization adjustment may enable the controller  140  to fine-tune and/or improve patterning performance during the exposure operation. 
     As indicated above,  FIG.  7    is provided as an example. Other examples may differ from what is described with regard to  FIG.  7   . 
       FIGS.  8 A- 8 D  are diagrams of example implementations of configurable pixels  702  described herein.  FIG.  8 A  illustrates an example implementation  810  in which a configurable pixel  702  is configured in an unpolarized configuration. As shown in  FIG.  8 A , the controller  140  transmits one or more signals to the actuator  724   a  to cause the actuator  724   a  to actuate the multilayer polarizer  502 . The actuation may include rotating the multilayer polarizer  502  as shown in  FIG.  8 A , translating the multilayer polarizer  502 , and/or displacing the multilayer polarizer  502 . The actuator  724   a  may actuate the multilayer polarizer  502  to move the multilayer polarizer  502  out of the light path of the unpolarized radiation  208  incident upon the multilayer polarizer  502 . As a result, the unpolarized radiation  208  instead is incident upon the multilayer mirror  402   a , which reflects the unpolarized radiation  208 . In this way, the multilayer polarizer  502  is moved out of the light path of the unpolarized radiation  208  such that the unpolarized radiation  208  remains unpolarized (e.g., the unpolarized radiation  208  is not split into TE polarized radiation and TM polarized radiation components). In some implementations, the controller  140  transmits another signal (or signals) to the multilayer mirror  402   a  to cause the actuator  724   b  to actuate the multilayer mirror  402   a  to position the multilayer mirror  402   a  to reflect the unpolarized radiation  208 . 
       FIG.  8 B  illustrates an example implementation  820  in which a configurable pixel  702  is configured in a TE polarized configuration. As shown in  FIG.  8 B , the controller  140  transmits one or more signals to the actuator  724   b  to cause the actuator  724   b  to actuate the multilayer mirror  402   a . The actuation may include rotating the multilayer mirror  402   a  as shown in  FIG.  8 B , translating the multilayer mirror  402   a , and/or displacing the multilayer mirror  402   a . The actuator  724   b  may actuate the multilayer mirror  402   a  to angle the multilayer mirror  402   a  such that the multilayer mirror  402   a  directs the transmitted TM polarized radiation  704   a  in a direction so as to refrain from providing the reflected TM polarized radiation  704   b . In this way, only the reflected TE polarized radiation  706  is provided by the configurable pixel  702  in the TE polarized configuration of the example implementation  820 . In some implementations, the controller  140  transmits another signal (or signals) to the multilayer polarizer  502  and/or to the multilayer mirror  402   b  to cause the multilayer polarizer  502  and/or to the multilayer mirror  402   b  to reflect the reflected TE polarized radiation  706 . 
       FIG.  8 C  illustrates an example implementation  830  in which a configurable pixel  702  is configured in a TM polarized configuration. As shown in  FIG.  8 C , the controller  140  transmits one or more signals to the actuator  724   c  to cause the actuator  724   c  to actuate the multilayer mirror  402   b . The actuation may include rotating the multilayer mirror  402   b  as shown in  FIG.  8 C , translating the multilayer mirror  402   b , and/or displacing the multilayer mirror  402   b . The actuator  724   c  may actuate the multilayer mirror  402   b  to angle the multilayer mirror  402   b  such that the multilayer mirror  402   b  directs the reflected TE polarized radiation  706  in a direction so as to refrain from providing the reflected TE polarized radiation  706 . In this way, only the reflected TM polarized radiation  704   b  is provided by the configurable pixel  702  in the TM polarized configuration of the example implementation  830 . In some implementations, the controller  140  transmits another signal (or signals) to the multilayer polarizer  502  and/or to the multilayer mirror  402   a  to cause the multilayer polarizer  502  and/or to the multilayer mirror  402   a  to reflect the reflected TM polarized radiation  704   b.    
       FIG.  8 D  illustrates an example implementation  840  in which a configurable pixel  702  is configured in a deactivated configuration. In the deactivated configuration, the configurable pixel  702  refrains from providing radiation output. As shown in  FIG.  8 D , the controller  140  transmits one or more signals to the actuator  724   a  to cause the actuator  724   a  to actuate the multilayer polarizer  502 . This causes the actuator  724   a  to move the multilayer polarizer  502  out of the light path of the unpolarized radiation  208  incident upon the multilayer polarizer  502 . Moreover, the controller  140  transmits one or more signals to the actuator  724   b  to cause the actuator  724   b  to actuate the multilayer mirror  402   a . This causes the actuator  724   b  to move the multilayer mirror  402   a  such that the multilayer mirror  402   a  is configured at an angle in which the multilayer mirror  402   a  directs the unpolarized radiation  208  such that no output of the configurable pixel  702  is provided. 
     As indicated above,  FIGS.  8 A- 8 D  are provided as examples. Other examples may differ from what is described with regard to  FIGS.  8 A- 8 D . 
       FIG.  9    is a diagram of an example implementation  900  of a configurable pixel  702  described herein. The example implementation  900  of a configurable pixel  702  is similar to the example implementation  700  of a configurable pixel  702  described above in connection with  FIG.  7   . In addition, the configurable pixel  702  in the example implementation  900  includes a mirror  902  that is positioned in the light path of the reflected TE polarized radiation  706  between the multilayer polarizer  502  and the multilayer mirror  402   b . The mirror  902  includes a tunable mirror, a single layer mirror, a multilayer mirror, a mirror including a coating formed on a substrate, or another type of mirror. The mirror  902  enables multilayer mirror  402   b  to be positioned further away from the multilayer polarizer  502 , which in turn enables the reflected TE polarized radiation  706  to be provided to different locations (e.g., further locations than without the use of the mirror  902 ) on the reticle  108 . Moreover, while the multilayer mirror  402   b  is illustrated in the example implementation  900  as being included in the configurable pixel  702 , in other implementations, the mirror  902  may be configured to provide the reflected TE polarized radiation  706  to a multilayer mirror  402  included in another pixel  204 . In this way, radiation from a plurality of pixels  204  can be combined to further increase the polarization flexibility of the illumination system  130   b.    
     The magnitude of the angle of incidence  904   a  of the TE polarized radiation  706  toward the multilayer mirror  402   b  relative to an axis  906  that is approximately perpendicular to the surface of reflection of the mirror  902 , and the magnitude of the angle of reflectance  904   b  of the reflected TE polarized radiation  706  reflected off of the mirror  902 , may each be included in a range of approximately 75 degrees to approximately 81 degrees to achieve a particular angle for the angle of incidence  720   a  toward the multilayer mirror  402   b  and/or to achieve a particular chief ray angle for the configurable pixel  702 . However, other values for the angle of incidence  904   a  and for the angle of reflectance  904   b  are within the scope of the present disclosure. 
     As further shown in  FIG.  9   , an actuator  908  may be included on the mirror  902  such that the mirror  902  may be actuated in addition to (or alternatively to) the multilayer polarizer  502 , the multilayer mirror  402   a , and/or the multilayer mirror  402   b . The controller  140  may communicate with the actuator  908  to cause the actuator  908  to actuate the mirror  902  to change or modify the polarization of the configurable pixel  702 . Moreover, the controller  140  may communicate with the actuator  908  to cause the actuator  908  to actuate the mirror  902  such that the mirror  902  provides the reflected TE polarized radiation  706  to a multilayer mirror  402  in a particular pixel  204  of the illumination system  130   b . In this way, the mirror  902  may be actuated to selectively direct the reflected TE polarized radiation  706  to different pixels  204 , which further increases the polarization flexibility of the illumination system  130   b.    
     As indicated above,  FIG.  9    is provided as an example. Other examples may differ from what is described with regard to  FIG.  9   . 
       FIGS.  10 A- 10 C  are diagrams of example pixel configurations for the illumination system  130   b  described herein for use in the lithography system  100  of  FIG.  1   . The example pixel configurations described in connection with  FIGS.  10 A- 10 C  enable the illumination system  130   b  to achieve and/or provide particular types of polarized EUV radiation (and/or other types of polarized radiation). The illumination system  130   b  may be configured in one or more of the example pixel configurations described in connection with  FIGS.  10 A- 10 C  using fixed polarized pixels (e.g., one or more of the pixels  302 ,  304 , and/or  306 ), configurable pixels  702 , and/or a combination thereof. In some implementations, illumination system  130   b  includes configurable pixels  702  and is capable of dynamically switching between pixel configurations (and thus, polarization configurations), which enables the illumination system  130   b  to provide free-form polarization. 
       FIG.  10 A  illustrates an example pixel configuration  1010 . In the example pixel configuration  1010 , the pixels  204  are configured in a TE polarized configuration. The pixels  204  may be configured as fixed TE polarized pixels (e.g., TE polarized pixels  304  as illustrated in  FIG.  5   ), as configurable pixels  702  that are configured in a TE polarized configuration as illustrated in  FIG.  8 B , or a combination thereof. In some implementations, the controller  140  transmits a signal to the pixels  204  to cause the associated actuators  724   a - 724   c , and/or  908  (or a subset thereof) to configure the pixels  204  in the TE polarized configuration. 
     In the example pixel configuration  1010 , the illumination system  130   b  is configured to generate and/or provide linear TE polarized radiation. Accordingly, the example pixel configuration  1010  may be referred to as a linear TE polarization configuration. In some implementations, the pixels  204  are configured to provide other types of linear polarized radiation such as linear TM polarized radiation. 
       FIG.  10 B  illustrates an example pixel configuration  1020 . In the example pixel configuration  1020 , a first subset of the pixels  204  are configured in a TE polarized configuration, a second subset of the pixels  204  are configured in a TM polarized configuration, and a third subset of the pixels  204  are configured in an unpolarized configuration. The first subset of the pixels  204  may be configured as fixed TE polarized pixels (e.g., TE polarized pixels  304  as illustrated in  FIG.  5   ), as configurable pixels  702  that are configured in a TE polarized configuration as illustrated in  FIG.  8 B , or a combination thereof. The second subset of the pixels  204  may be configured as fixed TM polarized pixels (e.g., TM polarized pixels  306  as illustrated in  FIG.  6   ), as configurable pixels  702  that are configured in a TM polarized configuration as illustrated in  FIG.  8 C , or a combination thereof. The third subset of the pixels  204  may be configured as fixed unpolarized pixels (e.g., unpolarized pixels  304  as illustrated in  FIG.  4   ), as configurable pixels  702  that are configured in an unpolarized configuration as illustrated in  FIG.  8 A , or a combination thereof. 
     In the example pixel configuration  1020 , the illumination system  130   b  is configured to generate and/or provide radial polarized radiation. Accordingly, the example pixel configuration  1020  may be referred to as a radial polarization configuration. In some implementations, the controller  140  transmits a first signal to the first subset of the pixels  204  to cause the associated actuators  724   a - 724   c , and/or  908  (or a subset thereof) to configure the first subset of the pixels  204  in the TE polarized configuration. In some implementations, the controller  140  transmits a second signal to the second subset of the pixels  204  to cause the associated actuators  724   a - 724   c , and/or  908  (or a subset thereof) to configure the second subset of the pixels  204  in the TM polarized configuration. In some implementations, the controller  140  transmits a third signal to the third subset of the pixels  204  to cause the associated actuators  724   a - 724   c , and/or  908  (or a subset thereof) to configure the third subset of the pixels  204  in the unpolarized configuration. 
       FIG.  10 C  illustrates an example pixel configuration  1030 . In the example pixel configuration  1030 , a first subset of the pixels  204  are configured in a TE polarized configuration, a second subset of the pixels  204  are configured in a TM polarized configuration, and a third subset of the pixels  204  are configured in an unpolarized configuration. The first subset of the pixels  204  may be configured as fixed TE polarized pixels (e.g., TE polarized pixels  304  as illustrated in  FIG.  5   ), as configurable pixels  702  that are configured in a TE polarized configuration as illustrated in  FIG.  8 B , or a combination thereof. The second subset of the pixels  204  may be configured as fixed TM polarized pixels (e.g., TM polarized pixels  306  as illustrated in  FIG.  6   ), as configurable pixels  702  that are configured in a TM polarized configuration as illustrated in  FIG.  8 C , or a combination thereof. The third subset of the pixels  204  may be configured as fixed unpolarized pixels (e.g., unpolarized pixels  304  as illustrated in  FIG.  4   ), as configurable pixels  702  that are configured in an unpolarized configuration as illustrated in  FIG.  8 A , or a combination thereof. 
     In the example pixel configuration  1030 , the illumination system  130   b  is configured to generate and/or provide azimuthal polarized radiation. Accordingly, the example pixel configuration  1030  may be referred to as an azimuthal polarization configuration. In some implementations, the controller  140  transmits a first signal to the first subset of the pixels  204  to cause the associated actuators  724   a - 724   c , and/or  908  (or a subset thereof) to configure the first subset of the pixels  204  in the TE polarized configuration. In some implementations, the controller  140  transmits a second signal to the second subset of the pixels  204  to cause the associated actuators  724   a - 724   c , and/or  908  (or a subset thereof) to configure the second subset of the pixels  204  in the TM polarized configuration. In some implementations, the controller  140  transmits a third signal to the third subset of the pixels  204  to cause the associated actuators  724   a - 724   c , and/or  908  (or a subset thereof) to configure the third subset of the pixels  204  in the unpolarized configuration. 
     It is noted that the quantity of pixels  204  included in the illumination system  130   b  illustrated and described in the implementations herein are examples, and other quantities of pixels  204  may be included in the illumination system  130   b . Similarly, it is noted that the pixel configurations described herein for the illumination system  130   b  are examples, and other pixel configurations are within the scope of the present disclosure. 
     As indicated above,  FIGS.  10 A- 10 C  are provided as examples. Other examples may differ from what is described with regard to  FIGS.  10 A- 10 C . 
       FIG.  11    is a diagram of example components of a device  1100 , which may correspond to the controller  140 , the illumination system  130   b , one or more of the actuators  724   a - 724   c , and/or another component. In some implementations, the lithography system  100 , the radiation source  102 , the exposure tool  104 , the controller  140 , the illumination system  130   b , one or more of the actuators  724   a - 724   c , and/or another component may include one or more devices  1100  and/or one or more components of device  1100 . As shown in  FIG.  11   , device  1100  may include a bus  1110 , a processor  1120 , a memory  1130 , an input component  1140 , an output component  1150 , and a communication component  1160 . 
     Bus  1110  includes one or more components that enable wired and/or wireless communication among the components of device  1100 . Bus  1110  may couple together two or more components of  FIG.  11   , such as via operative coupling, communicative coupling, electronic coupling, and/or electric coupling. Processor  1120  includes a central processing unit, a graphics processing unit, a microprocessor, a controller, a microcontroller, a digital signal processor, a field-programmable gate array, an application-specific integrated circuit, and/or another type of processing component. Processor  1120  is implemented in hardware, firmware, or a combination of hardware and software. In some implementations, processor  1120  includes one or more processors capable of being programmed to perform one or more operations or processes described elsewhere herein. 
     Memory  1130  includes volatile and/or nonvolatile memory. For example, memory  1130  may include random access memory (RAM), read only memory (ROM), a hard disk drive, and/or another type of memory (e.g., a flash memory, a magnetic memory, and/or an optical memory). Memory  1130  may include internal memory (e.g., RAM, ROM, or a hard disk drive) and/or removable memory (e.g., removable via a universal serial bus connection). Memory  1130  may be a non-transitory computer-readable medium. Memory  1130  stores information, instructions, and/or software (e.g., one or more software applications) related to the operation of device  1100 . In some implementations, memory  1130  includes one or more memories that are coupled to one or more processors (e.g., processor  1120 ), such as via bus  1110 . 
     Input component  1140  enables device  1100  to receive input, such as user input and/or sensed input. For example, input component  1140  may include a touch screen, a keyboard, a keypad, a mouse, a button, a microphone, a switch, a sensor, a global positioning system sensor, an accelerometer, a gyroscope, and/or an actuator. Output component  1150  enables device  1100  to provide output, such as via a display, a speaker, and/or a light-emitting diode. Communication component  1160  enables device  1100  to communicate with other devices via a wired connection and/or a wireless connection. For example, communication component  1160  may include a receiver, a transmitter, a transceiver, a modem, a network interface card, and/or an antenna. 
     Device  1100  may perform one or more operations or processes described herein. For example, a non-transitory computer-readable medium (e.g., memory  1130 ) may store a set of instructions (e.g., one or more instructions or code) for execution by processor  1120 . Processor  1120  may execute the set of instructions to perform one or more operations or processes described herein. In some implementations, execution of the set of instructions, by one or more processors  1120 , causes the one or more processors  1120  and/or the device  1100  to perform one or more operations or processes described herein. In some implementations, hardwired circuitry may be used instead of or in combination with the instructions to perform one or more operations or processes described herein. Additionally, or alternatively, processor  1120  may be configured to perform one or more operations or processes described herein. Thus, implementations described herein are not limited to any specific combination of hardware circuitry and software. 
     The number and arrangement of components shown in  FIG.  11    are provided as an example. Device  1100  may include additional components, fewer components, different components, or differently arranged components than those shown in  FIG.  11   . Additionally, or alternatively, a set of components (e.g., one or more components) of device  1100  may perform one or more functions described as being performed by another set of components of device  1100 . 
       FIG.  12    is a flowchart of an example process  1200  associated with configuring a pixel of an illumination system described herein. In some implementations, one or more process blocks of  FIG.  12    may be performed by a controller (e.g., the controller  140 , the device  1100 ). In some implementations, one or more process blocks of  FIG.  12    may be performed by another device or a group of devices separate from or including the controller, such as a lithography system (e.g., the lithography system  100 ), a radiation source (e.g., the radiation source  102 ), an exposure tool (e.g., the exposure tool  104 ), and/or an actuator (e.g., an actuator  724   a - 724   c ,  908 ), among other examples. Additionally, or alternatively, one or more process blocks of  FIG.  12    may be performed by one or more components of device  1100 , such as processor  1120 , memory  1130 , input component  1140 , output component  1150 , and/or communication component  1160 . 
     As shown in  FIG.  12   , process  1200  may include transmitting a first signal to cause at least one of a plurality of configurable pixels of an illumination system to be configured in a polarization configuration of a plurality of polarization configurations (block  1210 ). For example, the controller  140  may transmit a first signal to cause at least one of a plurality of configurable pixels  702  of the illumination system  130   b  to be configured in a polarization configuration of a plurality of polarization configurations (e.g., the polarization configurations described in connection with the example implementations  700 ,  810 - 840 , and/or  900 ), as described above. 
     As further shown in  FIG.  12   , process  1200  may include transmitting a second signal to cause a lithography system to perform an exposure operation while the at least one of the plurality of configurable pixels is configured in the polarization configuration (block  1220 ). For example, the controller  140  may transmit a second signal to cause a lithography system  100  to perform an exposure operation while the at least one of the plurality of configurable pixels  702  is configured in the polarization configuration, as described above. In some implementations, the illumination system  130   b  is included in the exposure tool  104  of the lithography system  100 . 
     Process  1200  may include additional implementations, such as any single implementation or any combination of implementations described below and/or in connection with one or more other processes described elsewhere herein. 
     In a first implementation, transmitting the first signal includes transmitting the first signal to cause each of the plurality of configurable pixels  702  to be configured in respective polarization configurations prior to the exposure operation. In a second implementation, alone or in combination with the first implementation, transmitting the first signal includes transmitting the first signal to cause each of the plurality of configurable pixels  702  to be configured in respective polarization configurations during the exposure operation. In a third implementation, alone or in combination with one or more of the first and second implementations, process  1200  includes determining (e.g., by the controller  140 ) a particular combination of respective polarization configurations for the plurality of configurable pixels  702  based on at least one of a contrast parameter for the exposure operation, or a throughput parameter for the exposure operation. 
     In a fourth implementation, alone or in combination with one or more of the first through third implementations, transmitting the first signal includes transmitting the first signal to cause at least a subset of the plurality of configurable pixels  702  to be configured in a TE polarized configuration (e.g., as illustrated in the example implementation  820 ). In a fifth implementation, alone or in combination with one or more of the first through fourth implementations, transmitting the first signal includes transmitting the first signal to cause a first subset of the plurality of configurable pixels  702  to be configured in a TE polarized configuration (e.g., as illustrated in the example implementation  820  as illustrated in the example implementation  820 ), a second subset of the plurality of configurable pixels  702  to be configured in a TM polarized configuration (e.g., as illustrated in the example implementation  830 ), and a third subset of the plurality of configurable pixels  702  to be configured in an unpolarized configuration (e.g., as illustrated in the example implementation  810 ). In a sixth implementation, alone or in combination with one or more of the first through fifth implementations, transmitting the first signal includes transmitting the first signal to respective one or more actuators  724   a - 724   c  and/or  908  associated with each of the plurality of configurable pixels  702  to cause the respective one or more actuators  724   a - 724   c  and/or  908  to configure the plurality of configurable pixels  702  in the respective polarization configurations. 
     Although  FIG.  12    shows example blocks of process  1200 , in some implementations, process  1200  may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in  FIG.  12   . Additionally, or alternatively, two or more of the blocks of process  1200  may be performed in parallel. 
       FIG.  13    is a flowchart of an example process  1300  associated with configuring a pixel of an illumination system described herein. In some implementations, one or more process blocks of  FIG.  13    may be performed by an illumination system (e.g., the illumination system  130   b , the device  1100 ). In some implementations, one or more process blocks of  FIG.  13    may be performed by another device or a group of devices separate from or including the illumination system, such as a lithography system (e.g., the lithography system  100 ), a radiation source (e.g., the radiation source  102 ), an exposure tool (e.g., the exposure tool  104 ), a controller (e.g., the controller  140 ), and/or an actuator (e.g., an actuator  724   a - 724   c ), among other examples. Additionally, or alternatively, one or more process blocks of  FIG.  13    may be performed by one or more components of device  1100 , such as processor  1120 , memory  1130 , input component  1140 , output component  1150 , and/or communication component  1160 . 
     As shown in  FIG.  13   , process  1300  may include configuring a plurality of multilayer mirrors and a multilayer polarizer of a configurable pixel included on a substrate of an illumination system (block  1310 ). For example, the illumination system  130   b  (e.g., the actuators  724   a - 724   c  and/or  908  of the illumination system  130   b ) may configure the multilayer mirrors  402   a  and  402   b  and the multilayer polarizer  502  of a configurable pixel  702  included on the substrate  206  of the illumination system  130   b , as described above. In some implementations, the illumination system  130   b  is included in an EUV exposure tool (e.g., the exposure tool  104 ) of the lithography system  100 . In some implementations, the plurality of multilayer mirrors  402   a  and  402   b  and the multilayer polarizer  502  are configured such that the configurable pixel  702  is configured in a particular polarization configuration (e.g., the polarization configurations described in connection with the example implementations  700 ,  810 - 840 , and/or  900 ). 
     As further shown in  FIG.  13   , process  1300  may include receiving unpolarized EUV radiation from a first mirror included in the EUV exposure tool during an exposure operation of the EUV exposure tool (block  1320 ). For example, the illumination system  130   b  may receive unpolarized EUV radiation (e.g., the unpolarized radiation  208 ) from a first mirror (e.g., the mirror  130   a ) included in the EUV exposure tool during an exposure operation of the EUV exposure tool, as described above. 
     As further shown in  FIG.  13   , process  1300  may include providing reflected EUV radiation to a second mirror included in the EUV exposure tool during the exposure operation (block  1330 ). For example, the illumination system  130   b  may provide reflected EUV radiation (e.g., the unpolarized radiation  208 , the reflected TM polarized radiation  704   b , and/or the reflected TE polarized radiation  706 ) to a second mirror (e.g., the mirror  132 ) included in the EUV exposure tool during the exposure operation, as described above. In some implementations, a polarization of the reflected EUV radiation is based on the unpolarized EUV radiation and the particular polarization configuration of the configurable pixel  702 . 
     Process  1300  may include additional implementations, such as any single implementation or any combination of implementations described below and/or in connection with one or more other processes described elsewhere herein. 
     In a first implementation, the particular polarization configuration includes a TE polarization configuration (e.g., as illustrated in the example implementation  820 ), and configuring the plurality of multilayer mirrors  402   a  and  402   b  and the multilayer polarizer  502  includes actuating a multilayer mirror (e.g., the multilayer mirror  402   a ), of the plurality of multilayer mirrors  402   a  and  402   b , below the multilayer polarizer  502  such that the reflected EUV radiation includes a  1 E polarized component (e.g., the reflected TE polarized radiation  706 ) of the unpolarized EUV radiation (e.g., the unpolarized radiation  208 ). 
     In a second implementation, alone or in combination with the first implementation, providing the reflected EUV radiation includes polarizing, using the multilayer polarizer  502 , the unpolarized EUV radiation (e.g., the unpolarized radiation  208 ) into the TE polarized component and a TM polarized component (e.g., the transmitted TM polarized radiation  704   a ), and reflecting, using another multilayer mirror (e.g., the multilayer mirror  402   b ) of the plurality of multilayer mirrors  402   a  and  402   b , the TE polarized component toward the second mirror (e.g., the mirror  132 ), the other multilayer mirror (e.g., the multilayer mirror  402   b ) is adjacent to the multilayer polarizer  502 , and the TM polarized component is directed away from the second mirror (e.g., the mirror  132 ) by the multilayer mirror (e.g., the multilayer mirror  402   a ). 
     In a third implementation, alone or in combination with one or more of the first and second implementations, the particular polarization configuration includes a TM polarization configuration (e.g., as illustrated in the example implementation  830 ), and configuring the plurality of multilayer mirrors  402   a  and  402   b  and the multilayer polarizer  502  includes actuating a multilayer mirror e.g., the multilayer mirror  402   b ), of the plurality of multilayer mirrors  402   a  and  402   b , adjacent to the multilayer polarizer  502  such that the reflected EUV radiation includes a TM polarized component (e.g., the reflected TM polarized radiation  704   b ) of the unpolarized EUV radiation (e.g., the unpolarized radiation  208 ). 
     In a fourth implementation, alone or in combination with one or more of the first through third implementations, providing the reflected EUV radiation includes polarizing, using the multilayer polarizer  502 , the unpolarized EUV radiation (e.g., the unpolarized radiation  208 ) into the TM polarized component and a TE polarized component (e.g., the reflected TE polarized radiation  706 ), and reflecting, using another multilayer mirror (e.g., the multilayer mirror  402   a ) of the plurality of multilayer mirrors  402   a  and  402   b , the TM polarized component toward the second mirror (e.g., the mirror  132 ), where the other multilayer mirror (e.g., the multilayer mirror  402   a ) is below the multilayer polarizer  502 , and the TE polarized component is directed away from the second mirror (e.g., the mirror  132 ) by the multilayer mirror e.g., the multilayer mirror  402   b ). 
     In a fifth implementation, alone or in combination with one or more of the first through fourth implementations, the particular polarization configuration includes an unpolarized polarization configuration (e.g., as illustrated in the example implementation  810 ), and configuring the plurality of multilayer mirrors  402   a  and  402   b  and the multilayer polarizer  502  includes actuating the multilayer polarizer  502  such that the reflected EUV radiation includes the unpolarized EUV radiation (e.g., the unpolarized radiation  208 ). 
     In a sixth implementation, alone or in combination with one or more of the first through fifth implementations, providing the reflected EUV radiation includes reflecting, using a multilayer mirror (e.g., the multilayer mirror  402   a ) of the plurality of multilayer mirrors  402   a  and  402   b , the unpolarized EUV radiation toward the second mirror (e.g., the mirror  132 ), where the multilayer mirror (e.g., the multilayer mirror  402   a ) is below the multilayer polarizer  502 . 
     Although  FIG.  13    shows example blocks of process  1300 , in some implementations, process  1300  may include additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in  FIG.  13   . Additionally, or alternatively, two or more of the blocks of process  1300  may be performed in parallel. 
       FIG.  14    is a flowchart of an example process  1400  associated with configuring a pixel of an illumination system described herein. In some implementations, one or more process blocks of  FIG.  14    may be performed by an illumination system (e.g., the illumination system  130   b , the device  1100 ). In some implementations, one or more process blocks of  FIG.  14    may be performed by another device or a group of devices separate from or including the illumination system, such as a lithography system (e.g., the lithography system  100 ), a radiation source (e.g., the radiation source  102 ), an exposure tool (e.g., the exposure tool  104 ), a controller (e.g., the controller  140 ), and/or an actuator (e.g., an actuator  724   a - 724   c ), among other examples. Additionally, or alternatively, one or more process blocks of  FIG.  14    may be performed by one or more components of device  1100 , such as processor  1120 , memory  1130 , input component  1140 , output component  1150 , and/or communication component  1160 . 
     As further shown in  FIG.  14   , process  1400  may include forming a photosensitive material on a semiconductor substrate (block  1410 ). For example, a deposition tool such as a spin-coating tool and/or another type of deposition tool may form a photosensitive material on a semiconductor substrate  110 , as described herein. The photosensitive material may include a photoresist, such as a positive photoresist, a negative photoresist, and/or another type of photoresist. 
     As shown in  FIG.  14   , process  1400  may include loading the semiconductor substrate after forming the photosensitive material on the semiconductor substrate (block  1420 ). For example, the lithography system  100  may load the semiconductor substrate  110  onto a substrate stage  136  of the lithography system  100  after the deposition tool forms the photosensitive material on the semiconductor substrate  110 , as described herein. 
     As further shown in  FIG.  14   , process  1400  may include configuring a plurality of multilayer mirrors and a multilayer polarizer of a configurable pixel included on a substrate of an illumination system (block  1430 ). For example, the illumination system  130   b  (e.g., the actuators  724   a - 724   c  and/or  908  of the illumination system  130   b ) may configure the multilayer mirrors  402   a  and  402   b  and the multilayer polarizer  502  of a configurable pixel  702  included on the substrate  206  of the illumination system  130   b , as described above. In some implementations, the illumination system  130   b  is included in an EUV exposure tool (e.g., the exposure tool  104 ) of the lithography system  100 . In some implementations, the plurality of multilayer mirrors  402   a  and  402   b  and the multilayer polarizer  502  are configured such that the configurable pixel  702  is configured in a particular polarization configuration (e.g., the polarization configurations described in connection with the example implementations  700 ,  810 - 840 , and/or  900 ). 
     As further shown in  FIG.  14   , process  1400  may include modulating unpolarized radiation and using the plurality of multilayer mirrors and the multilayer polarizer to form polarized radiation from the unpolarized radiation (block  1440 ). For example, the lithography system  100  may modulate unpolarized radiation and using the plurality of multilayer mirrors and the multilayer polarizer to form polarized radiation from the unpolarized radiation. In some implementations, the lithography system  100  modulates the unpolarized radiation by generating a laser beam  120 , which is used to generate EUV radiation  106  from droplets  118 , and by modulating the EUV radiation  106  that is provided to an exposure tool of the lithography system  100  where the plurality of multilayer mirrors and the multilayer polarizer are included. 
     As further shown in  FIG.  14   , process  1400  may include exposing the photosensitive material on the semiconductor substrate to the polarized radiation (block  1450 ). For example, the lithography system  100  may expose the photosensitive material on the semiconductor substrate  110  to the polarized radiation, as described herein. In some implementations, the polarized radiation is based on a particular polarization configuration of the configurable pixel. 
     Process  1400  may include additional implementations, such as any single implementation or any combination of implementations described below and/or in connection with one or more other processes described elsewhere herein. 
     In a first implementation, the particular polarization configuration includes a transverse electric (TE) polarization configuration, and configuring the plurality of multilayer mirrors and the multilayer polarizer includes actuating a multilayer mirror, of the plurality of multilayer mirrors, below the multilayer polarizer such that the polarized radiation includes a TE polarized component of the unpolarized radiation. 
     In a second implementation, alone or in combination with the first implementation, modulating the unpolarized radiation and using the plurality of multilayer mirrors and the multilayer polarizer to form the polarized radiation from the unpolarized radiation includes polarizing, using the multilayer polarizer, the unpolarized radiation into the TE polarized component and a transverse magnetic (TM) polarized component, and reflecting, using another multilayer mirror of the plurality of multilayer mirrors, the TE polarized component. 
     In a third implementation, alone or in combination with one or more of the first and second implementations, the particular polarization configuration includes a transverse magnetic (TM) polarization configuration, and configuring the plurality of multilayer mirrors and the multilayer polarizer includes actuating a multilayer mirror, of the plurality of multilayer mirrors, adjacent to the multilayer polarizer such that the polarized radiation includes a TM polarized component of the unpolarized radiation. 
     In a fourth implementation, alone or in combination with one or more of the first through third implementations, modulating the unpolarized radiation and using the plurality of multilayer mirrors and the multilayer polarizer to form the polarized radiation from the unpolarized radiation includes polarizing, using the multilayer polarizer, the unpolarized radiation into the TM polarized component and a transverse electric (TE) polarized component. 
     In a fifth implementation, alone or in combination with one or more of the first through fourth implementations, the particular polarization configuration includes an unpolarized polarization configuration, and configuring the plurality of multilayer mirrors and the multilayer polarizer includes actuating the multilayer polarizer such that the unpolarized radiation is directed toward the semiconductor substrate. 
     In a sixth implementation, alone or in combination with one or more of the first through fifth implementations, the multilayer mirror is below the multilayer polarizer. 
     Although  FIG.  14    shows example blocks of process  1400 , in some implementations, process  1400  includes additional blocks, fewer blocks, different blocks, or differently arranged blocks than those depicted in  FIG.  14   . Additionally, or alternatively, two or more of the blocks of process  1400  may be performed in parallel. 
     In this way, an illumination system includes a plurality of pixels (or spots) that are (or may be) configured in one or more polarization configuration types. The pixels of the illumination system may be configured to promote particular types of polarization (e.g., transverse electric (TE) polarization, transvers magnetic (TM) polarization) to increase pattern contrast while achieving suitable exposure operation throughput. Moreover, the pixels of the pixels of the illumination system may be configured to achieve free-form (arbitrary or freely-configurable) polarization, which permits the polarization of radiation to be tailored to particular exposure operation patterns and other parameters. 
     As described in greater detail above, some implementations described herein provide a method. The method includes forming a photosensitive material on a semiconductor substrate. The method includes loading the semiconductor substrate after forming the photosensitive material on the semiconductor substrate. The method includes configuring a plurality of multilayer mirrors and a multilayer polarizer of a configurable pixel included on a substrate of an illumination system. The method includes modulating unpolarized radiation and using the plurality of multilayer mirrors and the multilayer polarizer to form polarized radiation from the unpolarized radiation. The method includes exposing the photosensitive material on the semiconductor substrate to the polarized radiation. The polarized radiation is based on a particular polarization configuration of the configurable pixel. 
     As described in greater detail above, some implementations described herein provide a method. The method includes transmitting, by a controller, a first signal to cause at least one of a plurality of configurable pixels of an illumination system to be configured in a polarization configuration of a plurality of polarization configurations. The method includes transmitting, by the controller, a second signal to cause a lithography system to perform an exposure operation while the at least one of the plurality of configurable pixels is configured in the polarization configuration, where the illumination system is included in an exposure tool of the lithography system. 
     As described in greater detail above, some implementations described herein provide a method. The method includes configuring a plurality of multilayer mirrors and a multilayer polarizer of a configurable pixel included on a substrate of an illumination system, where the illumination system is included in an EUV exposure tool of a lithography system, and where the plurality of multilayer mirrors and the multilayer polarizer are configured such that the configurable pixel is configured in a particular polarization configuration. The method includes receiving unpolarized EUV radiation from a first mirror included in the EUV exposure tool during an exposure operation of the EUV exposure tool. The method includes providing reflected EUV radiation to a second mirror included in the EUV exposure tool during the exposure operation, where a polarization of the reflected EUV radiation is based on the unpolarized EUV radiation and the particular polarization configuration of the configurable pixel. 
     As described in greater detail above, some implementations described herein provide an illumination system for use in an EUV exposure tool. The illumination system for use in an EUV exposure tool includes a substrate. The illumination system for use in an EUV exposure tool includes a plurality of fixed IL polarized pixels. The illumination system for use in an EUV exposure tool includes a plurality of configurable pixels that are each capable of being selectively configured in a respective polarization configuration of a plurality of polarization configurations, where the plurality of polarization configurations include a TE polarized configuration, a TM polarized configuration, a TE polarized and TM polarized configuration, or an unpolarized configuration. 
     The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.