System and method of optical reflectometry

Abstract

An optical reflectance measurement system includes: a processing chamber; a substrate support configured to receive a substrate; a light source configured to transmit an incident light beam; an optical fiber bundle coupled to the light source and optically coupled to a lens assembly, wherein the lens assembly is optically coupled to at least a first optical fiber and configured to transmit through a transparent window to at least one region of the substrate and to receive from at least one region of the substrate; a beam splitter disposed within the optical fiber bundle; and a return optical fiber bundle coupled to the beam splitter and coupled to a detection system, wherein the detection system is configured to reference the reflected light beam to a reference beam to improve the signal-to-noise ratio, analyze the full spectrum of the reflected light beam, and determine at least one characteristic of at least one region of the substrate.

Description

Hyperspectral multi-point optical reflectometer Embodiments of the present disclosure generally relate to improvements in optical reflectance metrology for substrate processing systems. Since semiconductor devices were first introduced decades ago, the size of their geometries has decreased significantly. Increased circuit density places additional demands on the processes used to manufacture semiconductor devices. For example, as circuit density increases, pitch sizes rapidly decrease to dimensions below 50 nm, while vertical dimensions (such as trench depth) remain relatively constant. As a result, the aspect ratio of a feature (i.e., its height divided by its width) increases. The open area of ​​a device feature becomes a smaller and smaller percentage of the entire wafer, resulting in a smaller percentage of light containing information about the feature. At the same time, features with smaller openings tend to be deeper, which reduces the light that escapes from the bottom of the feature, further reducing the signal-to-noise ratio (SNR). Precisely controlling the dimensions of such high-density, submicron features is crucial for the reliable formation of semiconductor devices. Features, such as transistors and capacitors, are conventionally formed in semiconductor devices by patterning the surface of a substrate to define the feature's lateral dimensions and then etching the substrate to remove material and define the feature. To achieve features with the desired electrical performance, the feature dimensions must be within controlled specifications. This may require the use of dry or plasma etching processes to partially remove one or more layers. For example, for endpoint detection, interference fringe patterns can be simulated for each layer and then compared to the measured signal during etching. This method is very effective and can be used to monitor etching and endpoint detection in substrates with multiple layers on top. Typically, in-situ optical reflectometers use fiber optic cables to transmit light from the reflectometer and receive reflected light from a substrate in a substrate processing chamber. Conventional fiber optic cables can measure parameters such as film quality, film thickness, or the width of structures on a substrate. However, due to the large distance between the lens and the processed substrate, the effective beam size at the substrate varies from a few millimeters to over 10 millimeters. The large beam size makes it difficult to focus the beam on the wafer, and the reflected beam contains information from many features on the substrate that are not of interest. This makes it difficult to identify and filter the target features of interest. Therefore, there is a need in the art for improvements to in-situ optical reflectometers. Embodiments of the present disclosure generally relate to improvements in optical reflectometers for substrate processing systems. A general aspect includes an optical reflectance measurement system. The optical reflectance measurement system also includes a processing chamber having a top, sidewalls, and a bottom defining an interior volume, wherein the top includes a transparent window. The system also includes a substrate support positioned within the interior volume, wherein the substrate support is configured to receive a substrate. The system also includes a light source positioned outside the interior volume, wherein the light source is configured to transmit an incident light beam. The system also includes a fiber optic bundle positioned outside the interior volume, wherein the fiber optic bundle may include at least a first optical fiber coupled to the light source and optically coupled to a lens assembly, wherein the lens assembly is positioned above the transparent window and optically coupled to the at least first optical fiber and is configured to transmit to at least one region of the substrate through the transparent window and receive from at least one region of the substrate through the transparent window; and a beam splitter positioned within the fiber optic bundle. The system also includes a return fiber bundle, which may include at least a first return fiber coupled to a beam splitter and coupled to a detection system, wherein the detection system is configured to: reference a reference beam and a reflected beam to improve a signal-to-noise ratio (SNR), analyze the reflected beam, analyze a full spectrum of the reflected beam, and determine at least one characteristic of at least one region of the substrate based on the analysis of the full spectrum of the reflected beam. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs stored on one or more computer storage devices, each configured to perform the actions of the method. One general aspect includes a method for optical reflectance measurement. The method also includes transmitting an incident light beam from a light source to a beam splitter via a fiber optic bundle that may include at least a first optical fiber. The method also includes transmitting a first portion of the incident light beam from the beam splitter to a lens assembly via the fiber optic bundle. The method also includes transmitting a second portion of the incident light beam from the beam splitter to a detection system as a reference beam via a return fiber optic bundle that may include a plurality of return optical fibers. The method also includes focusing the first portion of the incident light beam as an incident light beam from the lens assembly onto at least one region of a substrate disposed within a processing chamber. The method also includes receiving reflected light from the at least one region of the substrate at the lens assembly. The method also includes transmitting the reflected light as a reflected light beam from the lens assembly to the beam splitter via the fiber optic bundle. The method also includes transmitting the reflected light beam from the beam splitter to the detection system via a return fiber optic bundle. The method also includes determining at least one characteristic of at least one region of the substrate. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs stored on one or more computer storage devices, each configured to perform the actions of the method. Examples of the present disclosure generally relate to improvements in optical reflectance metrology for substrate processing systems. FIG1 is a schematic cross-sectional view of an example processing chamber 100 from a substrate processing system having a detection system 164 according to one embodiment of the present disclosure. Suitable processing chambers include inductively coupled and capacitively coupled plasma etch chambers, such as TETRA ® Photomask etching system and SYM3 ® etch systems (both available from Applied Materials, Inc., Santa Clara, Calif.), and other systems. Other types of processing chambers may be adapted to benefit from the present invention, including, for example, capacitively coupled parallel plate chambers and magnetically enhanced ion etch chambers, as well as inductively coupled plasma etch chambers. The processing chamber 100 includes a chamber body 102 and a top plate 103 that is energy-transparent, i.e., allows energy and light to pass therethrough. The chamber body 102 has sidewalls, a top plate 103, and also a chamber bottom 107. The chamber body 102, the sidewalls, the top plate 103, and the chamber bottom 107 define the interior volume of the processing chamber 100. The chamber body 102 is fabricated from a metal, such as anodized aluminum or stainless steel. The top plate 103 is mounted on the chamber body 102. The top plate 103 can be flat, rectangular, arcuate, conical, dome-shaped, or multi-radius-shaped. The top plate 103 is fabricated from an energy-transparent material, such as ceramic or other dielectric materials. An induction coil 126 is disposed above the top plate 103 of the processing chamber 100 and is used to energize the gas within the processing chamber 100 during processing. A substrate support 116 having a substrate supporting surface 188 for supporting the substrate 120 during processing is disposed in the processing chamber 100. The substrate support 116 may include an electrostatic chuck, wherein at least a portion of the substrate support 116 is electrically conductive and capable of serving as a process bias cathode. Process gases are introduced into the processing chamber 100 from a process gas source 148 through a gas distributor 122. The gas distributor 122 may be disposed in the ceiling 103 or the chamber body 102 above the substrate support 116. Mass flow controllers (not shown) for each process gas, or alternatively for a mixture of process gases, are disposed between the gas distributor 122 and the process gas source 148 to regulate the respective flow rates of the process gases into the chamber body 102. An interior volume 114 is defined within the chamber body 102 between a substrate support 116 and a top plate 103. Plasma is formed within the interior volume 114 from the process gas using a coil power supply 127, which supplies power to an inductive coil 126 to generate an electromagnetic field within the interior volume 114 via an RF matching network 135. The substrate support 116 may include an electrode disposed therein, which is powered by the electrode power supply 125 and generates a capacitive electric field within the processing chamber 100 via an RF matching network 128. RF power is applied to the electrode in the substrate support 116 when the chamber body 102 is electrically grounded. The capacitive electric field is transverse to the plane of the substrate support 116 and influences the directionality of charged species more orthogonal to the substrate 120, providing a more vertically oriented anisotropic etch of the substrate 120. The process gases and etchant byproducts are exhausted from the processing chamber 100 through an exhaust system 130. The exhaust system 130 can be disposed in the chamber bottom 107 of the processing chamber 100 or in another portion of the chamber body 102 of the processing chamber 100 to remove the process gases. A throttle valve 132 is disposed in the exhaust port 134 to control the pressure in the processing chamber 100. FIG. 1 further illustrates a fiber optic bundle 104 configured to detect features within or on a substrate 120 disposed in the processing chamber 100. The fiber optic bundle 104 has a diameter of approximately 0.05 mm to approximately 2 mm. For example, the fiber optic bundle 104 has a diameter of approximately 1 mm. In one example, the fiber optic bundle 104 is included in a detection system 164. The detection system 164 may be an optical reflectance measurement system. For example, a spectroscopic reflectance measurement system may be configured to process input channels and determine one or more characteristics of a substrate disposed in the processing chamber. For example, the detection system 164 may be an interferometer endpoint detection system configured to process input channels and determine one or more characteristics of a substrate disposed in the processing chamber 100. In one example, which may be combined with other examples, the detection system 164 is capable of processing multiple input channels simultaneously. For example, the detection system 164 may be capable of processing between approximately 1 and approximately 20 input channels simultaneously. For example, the detection system 164 may be capable of processing between approximately 10 and approximately 50 input channels simultaneously. For example, the detection system 164 may be capable of processing between approximately 10 input channels simultaneously. In one embodiment, which may be combined with other embodiments, detection system 164 can switch between groups of input channels (not shown) to measure additional areas of substrate 120. For example, detection system 164 can include several groups, each group having several input channels. For example, detection system 164 can include between approximately 1 and approximately 20 groups. For example, detection system 164 can include between at least 1 and approximately 20 groups. For example, detection system 164 can include 10 groups. Each group includes several input channels. For example, each group includes between approximately 1 and approximately 20 input channels. For example, each group includes between approximately 10 and approximately 50 input channels. For example, each group includes between approximately 10 input channels. In one embodiment, which may be combined with other embodiments, the detection system 164 determines one or more characteristics of the substrate (such as feature size, feature height, plasma radiation emission, changes in plasma characteristics, or the like) to determine the endpoint of one or more stages of the etching process. For example, the endpoint of an etching stage may occur when a layer of the substrate 120 has been sufficiently removed or etched through to expose underlying layers. In another embodiment, the endpoint of an etching state may occur when a desired dimension (such as a desired feature height) has been achieved. Determining the endpoint of an etching stage allows the etching of the substrate 120 to be stopped once the stage has been completed, thereby reducing the occurrence of over- or under-etching of the substrate 120. The endpoint of one or more stages may be determined by monitoring radiation emission from the plasma in the processing chamber 100, the intensity and wavelength of the plasma emission radiation varying based on changes in the composition of the excitation gas. For example, changes in the composition of the excitation gas may be caused by etching through an overburden layer to expose underlying layers on the substrate 120. Thus, the detection system 164 monitors one or more characteristics of the radiation emission to determine the extent of substrate etching or other conditions within the processing chamber 100 . Characteristics of one or more stages of substrate processing in the processing chamber 100 can be determined by the detection system 164. In one example, the endpoint of a substrate processing stage can occur when a layer of the substrate 120 has been sufficiently removed or etched through to expose underlying layers. In another example, the endpoint of a substrate processing stage can occur when a desired dimension (such as a desired feature height or film thickness) has been achieved. Determining the endpoint of a substrate processing stage allows processing of the substrate 120 to be stopped once the stage has been completed, thereby reducing substrate defects, such as over-etching or under-etching of the substrate 120. The endpoint of one or more substrate processing stages can be determined by monitoring radiation emission from the plasma in the processing chamber 100, where the intensity and wavelength of the emitted radiation vary based on changes in the composition of the excitation gas. For example, changes in the composition of the excitation gas can be caused by etching through an overburden layer to expose underlying layers on the substrate 120. Thus, the detection system 164 analyzes the radiation emission to determine the extent of substrate processing or other conditions in the processing chamber 100. The detection system 164 further includes a light source 166, a lens assembly 168, a light detector 170, a beam splitter 172, and a controller 150. The light source 166 is configured to emit a light beam through the beam splitter 172 and through the fiber bundle 104. The light beam strikes the substrate 120 and reflects back through the fiber bundle 104. After passing through the fiber bundle 104 and the beam splitter 172, the light beam returns to the light detector 170. For example, the lens assembly 168 is configured to focus the light beam into an incident light beam 176. The incident light beam 176 passes through the top plate 103 toward the substrate support surface 188 and illuminates an area or beam spot 180 on the surface 121 of the substrate 120. In one embodiment, which may be combined with other embodiments, the detection system 164 can manipulate the lens assembly 168 so that the beam spot 180 falls on different areas of the substrate 120 for measurement. Incident light beam 176 is reflected by surface 121 of substrate 120 to form reflected light beam 178. At least a portion of reflected light beam 178 is directed in a direction perpendicular to substrate support surface 188 through top plate 103, through fiber bundle 104, and through beam splitter 172 back to light detector 170. Light detector 170 is configured to measure the intensity of reflected light beam 178. An exemplary light detector 170 is a spectrometer. Alternatively, the fiber optic bundle 104 can be used without the lens assembly 168, such that the fiber optic bundle 104 is coupled directly to the top plate 103, which has a single collimator disposed between the fiber optic bundle 104 and the top plate 103. For example, the focusing lens 174b (i.e., serving as the collimator) can be disposed directly between the fiber optic bundle 104 and the top plate 103. In the embodiments described herein, a collimator may not be present. Light source 166 comprises a monochromatic or polychromatic light source that generates an incident light beam 176 for illuminating a beam spot 180 on substrate 120. The intensity of incident light beam 176 is selected to be sufficiently high so that reflected light beam 178 has a measurable intensity. In one example, light source 166, such as a xenon (Xe) lamp, provides polychromatic light and produces an emission spectrum with wavelengths ranging from approximately 200 nm to approximately 800 nm. Light source 166 may comprise a polychromatic source. The polychromatic light may be filtered to select frequencies that comprise incident light beam 176. A color filter may be placed before light detector 170 to remove all but the desired wavelength of light before measuring the intensity of reflected light beam 178 entering light detector 170. Light source 166 may also comprise a monochromatic source, such as a helium-neon (He-Ne) laser, a neodymium-doped yttrium aluminum garnet (Nd-YAG) laser, an LED, or other monochromatic light source, providing light of a selected wavelength. One or more mirrors 186 and one or more focusing lenses (such as focusing lenses 174a and 174b) can be used to focus incident light beam 176 from light source 166 to form a beam spot 180 on surface 121 of substrate 120. One or more mirrors 186 and one or more focusing lenses (such as focusing lenses 174a and 174b) can be used to focus reflected light beam 178 back onto the active surface of light detector 170. In one embodiment, which can be combined with other embodiments, the one or more mirrors can be fixed mirrors, adjustable mirrors, or digital mirror devices (DMDs). The size or area of ​​beam spot 180 should be large enough to compensate for variations in the surface topography of substrate 120 and device design features. The size of beam spot 180 enables detection of features and characteristics of substrate 120, such as feature pitch and depth, film thickness, and other physical properties. The area of ​​the reflected beam should be large enough to activate a substantial portion of the active light detection surface of light detector 170. The incident light beam 176 and the reflected light beam 178 are directed through a transparent window 182 of the processing chamber 100. The transparent window 182 allows the incident light beam 176 and the reflected light beam 178 to pass into and out of the processing environment of the processing chamber 100. A substrate supporting surface 188 of the substrate support 116, on which the substrate 120 rests, is disposed parallel to the top plate 103. In one example, the transparent window 182 is located in the top plate 103 of the processing chamber 100 and is oriented relative to the substrate 120 and the substrate support 116. The transparent window 182 is configured to receive the incident light beam from the detection system 164. The transparent window 182 enables the incident light beam 176 to be transmitted to the substrate. The transparent window 182 also enables the reflected light beam 178 to pass therethrough after being reflected from the substrate 120. The transparent window 182 is further configured to transmit the reflected light beam 178 to the detection system 164. Controller 150 is electrically coupled to detection system 164 via connection 158, which includes light detector 170, controller 150, and light source 166. Controller 150 calculates a portion of the real-time measured waveform spectrum of reflected light beam 178 reflected from beam spot 180 on substrate 120 and processes the spectrum using advanced spectral analysis techniques, including comparing the spectrum to stored characteristic waveform patterns. In one embodiment, which may be combined with other embodiments, controller 150 calculates and adjusts the position and orientation of lens assembly 168. The controller 150 includes a programmable central processing unit (CPU) 152 operable in conjunction with a memory 154 (e.g., non-volatile memory) and support circuits 156. The support circuits 156 are conventionally coupled to the CPU 152 and include cache memory, clock circuits, input / output subsystems, power supplies, and the like, and combinations thereof, coupled to various components of the processing chamber 100 to facilitate control thereof. The CPU is one of any form of general-purpose computer processor used in industrial settings, such as a programmable logic controller (PLC), to control the various components and subprocessors of a processing system. Memory 154 coupled to CPU 152 is non-transitory and typically one or more readily available memories, such as random access memory (RAM), read-only memory (ROM), a floppy disk drive, a hard disk, or any other form of digital storage (local or remote). Typically, memory 154 is in the form of a non-transitory computer-readable storage medium (e.g., non-volatile memory) containing instructions that, when executed by CPU 152, facilitate the operation of processing chamber 100. The instructions in memory 154 are in the form of a program product, such as a program that implements the methods of the present disclosure. The program code may conform to any of several different programming languages. In one example, the present disclosure may be implemented as a program product stored on a computer-readable storage medium for use with a computer system. The programs in the program product define the functionality of the embodiments (including the methods described herein). Illustrative non-transitory computer-readable storage media include, but are not limited to: (i) non-writable storage media on which information can be permanently stored (e.g., a read-only memory device within a computer, such as a CD-ROM disc readable by a CD-ROM drive, flash memory, a ROM chip, or any type of solid-state non-volatile semiconductor memory device, such as a solid-state drive (SSD)); and (ii) writable storage media on which variable information can be stored (e.g., a floppy disk within a disk drive or a hard disk drive, or any type of solid-state random-access semiconductor memory). Such computer-readable storage media, when carrying computer-readable instructions that direct the functions of the methods described herein, are embodiments of the present disclosure. In some embodiments, the methods described herein, or portions thereof, are performed by one or more application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other types of hardware implementations. In some other embodiments, the substrate processing and / or handling methods described herein are performed by a combination of software routines, ASICs, FPGAs, and / or other types of hardware implementations. One or more controllers 150 may be used with one or any combination of the various systems described herein. FIG. 2 is a schematic cross-sectional view of an example of a collimated optical path with optical fibers configured to transmit and receive light in a processing chamber, as commonly employed in the prior art. An incident light beam 176 originating from light source 166 is collected by fiber bundle 104. The incident light beam is received by beam splitter 172. In some examples, beam splitter 172 is positioned along the length of fiber bundle 104. In other examples, beam splitter 172 may be positioned at light source 166. The incident light beam 176 originating from light source 166 passes through beam splitter 172 and exits fiber bundle 104 at fiber bundle outlet 264. Fiber bundle outlet 264 is positioned above lens assembly 168, which includes a lens that acts as a collimator. The incident light beam 176 has an initial spot size approximately equal to the diameter of the optical fiber. For example, the diameter of initial spot size 260 may be approximately 100 microns (μm). As each of the incident light rays 236 interacts with a different portion of lens assembly 168, the incident light beam 176 exits fiber bundle outlet 264 in an expanded pattern. The incident light ray 236 is next passed through the lens assembly 168, where it is collimated and transmitted toward the substrate 120. After striking the substrate 120, the incident light ray 236 is reflected back toward the fiber optic bundle 104 as a reflected light ray 240. Due to spatial limitations, the distance from the fiber bundle outlet 264 to the lens assembly 168 is typically less than the distance between the lens assembly 168 and the surface of the substrate 120. This results in an enlargement of the substrate image size 242 on the surface of the substrate 120 compared to the size of the initial spot size 260. For example, the diameter of the substrate image size 242 can be 10 millimeters (mm). For example, the diameter of the substrate image size 242 can be 100 mm. The area of ​​the substrate image size 242 is the area to be measured by the detection system 164. After passing through the lens assembly, the reflected light rays 240 return to the optical fiber bundle 104. The reflected light rays 240 collectively constitute the reflected light beam 178. The reflected light rays 240 then return to the beam splitter 172. A first portion (e.g., approximately 50%) of the reflected light beam 178 received at the beam splitter 172 is then transmitted to the detection system 164 via the return optical fiber bundle 208. FIG. 3 is an example schematic cross-sectional diagram illustrating the optical path of a single optical fiber configured to transmit and receive light in the processing chamber 100 for improved spatial resolution on a substrate. An incident light beam 176 emitted by light source 166 is received by fiber bundle 104. Fiber bundle 104 includes a plurality of optical fibers. Each of the plurality of optical fibers in fiber bundle 104 has a diameter between approximately 0.01 mm and 1 mm. For example, each of the plurality of optical fibers in fiber bundle 104 has a diameter of approximately 0.5 mm. Fiber bundle 104 transmits incident light beam 176 and receives it via beam splitter 172. In some embodiments, beam splitter 172 is positioned along the length of fiber bundle 104. In other embodiments, beam splitter 172 may be positioned at light source 166. In other embodiments, beam splitter 172 may be positioned at the end of fiber bundle 104. A first portion (e.g., approximately 50%) of the received incident light beam 176 is transmitted through the beam splitter 172 as a reference beam 206, through the return fiber bundle 208, and the detection system 164. The reference beam 206 is received by the detection system 164 and used as a reference to reduce noise and improve the signal-to-noise ratio (SNR). A second portion (e.g., approximately 50%) of the received incident light beam 176 is transmitted through the beam splitter 172 and exits the fiber bundle 104 at the fiber bundle outlet 264. Fiber bundle outlet 264 is positioned above lens assembly 168, illustrated with fiber-to-lens distance 252. Incident light beam 176 has an initial spot size approximately equal to the diameter of a fiber in the plurality of fibers of fiber bundle 104. For example, initial spot size 260 has a diameter between approximately 0.01 mm and 1 mm. For example, initial spot size 260 has a diameter of approximately 0.5 mm. Fiber-to-lens distance 252 is approximately 40 millimeters (mm) to approximately 80 mm. For example, fiber-to-lens distance 252 is approximately 50 mm. The focusing lens assembly 168 has a lens-to-substrate distance 254 from the substrate 120. The lens-to-substrate distance 254 is based on the ratio of the fiber-to-lens distance 252. For example, the ratio of the lens-to-substrate distance 254 is between about 1:1 and about 10:1. For example, the ratio of the lens-to-substrate distance 254 is about 4:1. In another example, the ratio of the lens-to-substrate distance 254 is about 5:1. As the incident light rays 236 each interact with a different portion of the lens assembly 168, the incident light beam 176 exits the fiber bundle outlet 264 in a spread pattern. The incident light rays 236 then pass through the lens assembly 168 where they are focused, but not collimated, and transmitted toward the substrate 120. After striking substrate 120, incident light ray 236 is reflected back to fiber bundle 104 as reflected light ray 240. Due to spatial limitations, the distance from fiber bundle outlet 264 to lens assembly 168 is typically less than the distance between lens assembly 168 and the surface of substrate 120. This results in an enlargement of substrate image size 242 on the surface of substrate 120. For example, substrate image size 242 can be larger than initial spot size 260 by approximately the ratio of lens-to-substrate distance 254 to fiber-to-lens distance 252. For example, substrate image size 242 has a diameter between approximately 0.01 mm and 10 mm. For example, substrate image size 242 has a diameter of approximately 0.4 millimeters (mm). For example, substrate image size 242 has a diameter of approximately 0.1 mm. For example, substrate image size 242 has a diameter of approximately 4 mm. As compared to FIG. 2 , the optical path described herein provides a reduction in substrate image size 242. Reducing the substrate image size 242 results in the reflected signal / spectrum containing less information about non-targeted areas of the substrate, thereby increasing system sensitivity and detail resolution. Reflected light rays 240 return to lens assembly 168. After passing through lens assembly 168, reflected light rays 240 are transmitted to fiber optic bundle 104. Reflected light rays 240 collectively constitute reflected light beam 178. In one embodiment, fiber optic bundle 104 can be concentric with lens assembly 168. Received reflected light rays 240 are then transmitted to beam splitter 172. A first portion (e.g., approximately 50%) of reflected light beam 178 received at beam splitter 172 is then transmitted to detection system 164 via return fiber optic bundle 208. A second portion (e.g., approximately 50%) of reflected light beam 178 received at beam splitter 172 is transmitted to light source 166 via fiber optic bundle 104. FIG. 4 is a schematic cross-sectional diagram illustrating a fiber bundle design of a multi-point hyperspectral system and an optical path having a fiber bundle 310 configured to transmit and receive light in a processing chamber 100 . The incident light beam 176 from the light source 166 is collected by a fiber bundle 310. The fiber bundle 310 has a diameter of approximately 0.05 mm to approximately 2 mm. For example, the fiber bundle has a diameter of approximately 1 mm. The fiber bundle includes a plurality of optical fibers 302. For example, optical fiber 302a, optical fiber 302b, optical fiber 302c, and optical fiber 302d. Each of the plurality of optical fibers 302 has a diameter between approximately 0.01 mm and 1 mm. For example, optical fiber 302 has a diameter of approximately 0.5 mm. Each of the plurality of optical fibers 302 includes a fiber bundle outlet 264. The incident light beam 176 is transmitted to the beam splitter 172 via the plurality of optical fibers 302. In some examples, the beam splitter 172 is positioned along the length of the optical fiber bundle 104. In other examples, the beam splitter 172 can be positioned at the light source 166. In one example, approximately 50% of the received incident light beam 176 exits through the beam splitter 172 and is passed as the reference beam 206 through the return fiber bundle 312 comprising the plurality of return optical fibers 302 to the detection system 164. In other examples, a lower or higher percentage of the received incident light beam 176 exits through the beam splitter 172 and is passed as the reference beam 206 through the return fiber bundle 312 and the detection system 164. In one example, which may be combined with other examples, the beam splitter 172 optically separates the reference beam 206 from the incident beam 176. In another example, which may be combined with other examples, the beam splitter 172 separates the reference beam 206 from the incident beam 176 by redirecting a portion of the plurality of optical fibers 302 from the fiber bundle 310 to the return fiber bundle 312. In one example, which may be combined with other examples, the reference beam 206 may be attenuated before being received by the detection system 164. In one example, which may be combined with other examples, the reference beam 206 may be attenuated by the detection system 164. As shown and explained below in FIG. 5A , the detection system 164 uses the reference beam 206 to reduce noise and improve the signal-to-noise ratio (SNR). In another example, which may be combined with other examples, the beamsplitter 172 may allow the first portions of the plurality of return fibers to each receive a sub-portion of the reference beam corresponding to the region of the light source 166, and allow the second portions of the plurality of return fibers to each receive a sub-portion of the reflected beam that originally corresponded to the same region of the light source. As shown and explained below in FIG. 5B , this allows for additional SNR improvement, or allows for improved SNR of measurements of each region of the substrate by the detection system 164. The remaining portion of the received incident light beam 176 (approximately 50% of the light originating from the light source 166) passes through the beam splitter 172 and exits the fiber optic bundle 310 from the plurality of optical fibers 302 as incident light rays 236. For example, incident light rays 236 from optical fiber 302a, incident light rays 236 from optical fiber 302b, incident light rays 236 from optical fiber 302c, and incident light rays 236 from optical fiber 302d are all directed toward the focusing lens 174b. In other examples, a smaller or larger percentage of the light originating from the light source 166 passes through the beam splitter 172 and exits the fiber optic bundle 310 from the plurality of optical fibers 302 as incident light rays 236. The fiber bundle outlet 264 of the fiber bundle 310 is positioned farther from the focal point of the focusing lens 174b, as shown by the fiber-to-lens distance 252. The fiber-to-lens distance 252 is approximately 40 millimeters (mm) to approximately 80 mm. For example, the fiber-to-lens distance 252 is approximately 50 mm. The focusing lens 174b additionally has a lens-to-substrate distance 254 from the substrate 120. An incident light ray 236 passes through the focusing lens 174b. The incident light ray 236 exits the focusing lens 174b and impacts the substrate 120 within or near a substrate image size 242. The substrate image size 242 formed by the incident light ray 236 has an area that is larger than the outlet of the fiber bundle 310. The larger area of ​​the substrate image size 242 is typically due to space constraints. For example, the fiber-to-lens distance 252 is typically smaller than the lens-to-substrate distance 254, resulting in an increased area of ​​the substrate image size 242 on the substrate. After striking substrate 120, reflected light 178 as reflected light 240 is reflected back into fiber bundle 310. Reflected light 240, reflected by substrate 120, returns to focusing lens 174b. After passing through focusing lens 174b, reflected light 240 returns to the same fiber in the plurality of optical fibers 302 from which incident light 236 originated. For example, reflected light 240 returns to fiber 302a, fiber 302b, fiber 302c, and fiber 302d. In other embodiments, which may be combined with other embodiments, reflected light 240 returns to a different fiber in the plurality of optical fibers 302 than the fiber in the plurality of optical fibers from which incident light 236 originated. Reflected light 240 then returns to beam splitter 172. Approximately 50% of reflected light beam 178 received at beam splitter 172 is then transmitted via return fiber optic bundle 312 to light detector 170 of detection system 164. Approximately 50% of reflected light beam 178 received at beam splitter 172 is then transmitted via fiber optic bundle 310 to light source 166. In one example, which may be combined with other examples, the detection system 164 is capable of measuring multiple wavelengths (broadband spectrum) of the reflected light beam 178 collected by each of the plurality of optical fibers 302 . In other embodiments that may be combined with other embodiments, the reflected light beam 178 may be filtered or unfiltered, attenuated or unattenuated, and a photodiode or a charge-coupled device (CCD) employed in the detection system 164 may be used to measure the total power in each of the plurality of optical fibers 302. In other embodiments that may be combined with other embodiments, the detection system 164 is capable of simultaneously measuring multiple wavelengths (broadband spectrum) of the reflected light beam 178 collected by each of the plurality of optical fibers 302. Each of the plurality of optical fibers 302 transmits the reflected light 240 collected from a different location on the substrate to a different portion of the detection system 164, enabling the detection system 164 to simultaneously perform multi-location, multi-spectral measurements. FIG4A is a cross-sectional view of the exit of a fiber optic bundle 310 configured to transmit and receive light in a processing chamber 100 according to one embodiment of the present disclosure. More specifically, FIG4A shows that an incident light beam 176 as incident light ray 236 has been transmitted 236 through a plurality of optical fibers 302. The incident light ray 236 emitted from each fiber optic bundle exit 264 has an initial spot size 260 that is approximately equal to the diameter of the fiber optic bundle 104. The initial spot size 260 of the plurality of optical fibers 302 is a reduction relative to the initial spot size 260 shown in FIG2 . FIG4B is an exemplary cross-sectional view of a light beam transmitted from a plurality of optical fibers 302 in a receiving state and reflected from a surface of a substrate 120 according to one embodiment of the present disclosure. More specifically, FIG4B is a cross-sectional view of an incident light beam 236 received from a plurality of optical fibers 302, namely, optical fibers 302a, 302b, 302c, and 302d, and reflected as reflected light beam 240 from a plurality of reflection regions 302′, namely, reflection region 302a′, reflection region 302a′, reflection region 302a′, and reflection region 302a′, which fall within or near a substrate image size 242 on the substrate 120 shown in FIG4 . The reflected light beam 240 emitted from the reflection region 302′ has a substrate image size 242. The substrate image size 242 is larger than the initial spot size 260. For example, the substrate image size 242 has a diameter between approximately 0.1 mm and 10 mm. The substrate image size 242 is approximately 0.05 mm to 4 mm. For example, the substrate image size 242 is approximately 1 mm. The substrate image size 242 shown in FIG. 4B is reduced relative to the substrate image size 242 shown in FIG. 2B . Each of the plurality of reflective regions 302 ′ simultaneously returns a polychromatic reflectance spectrum from a different region of the substrate for analysis and measurement by the detection system 164 . The fiber bundle 310 disclosed herein achieves an increased number of reflective regions 302' by including a plurality of optical fibers 302. Each of the reflective regions 302' includes a reduced substrate image size 242, which is a reduction relative to the substrate image size 242 of the example of FIG. 2. In one embodiment, which may be combined with other embodiments, reducing the input fiber diameter allows for a reduced substrate image size 242, which allows for an improvement in spatial resolution of approximately ten times or more when compared to current reflectance measurement devices and methods. In another example, which may be combined with other examples, the fiber bundle 310 disclosed herein, by having a plurality of optical fibers 302, improves reflectometer sensitivity by allowing the full spectrum of each optical fiber to measure smaller, separate areas of the substrate. In another example, which may be combined with other examples, increasing the number of reflective regions 302', each with a reduced substrate image size 242, allows for simultaneous and separate analysis of more areas of the substrate, resulting in increased sensitivity compared to current reflectance measurement devices and methods. In another example, which may be combined with other examples, increasing the number of reflective regions 302' with reduced substrate image size 242 allows for differential measurement with improved detection sensitivity. For example, reflective region 302a' may fall on a portion of the substrate that is featureless, has fewer features, or has more features than reflective region 302d', thereby allowing for differential measurement between two areas of the substrate. In another example, which may be combined with other examples, increasing the number of reflective regions 302' with reduced substrate image size 242 allows each portion of the reflected light beam 178 collected by the plurality of optical fibers 302 to enter a different portion of the detection system 164 for analysis. FIG. 5A illustrates a graph 500 titled “Single Wavelength Reference” showing the intensity drift of an example light source (e.g., light source 166) over time and how a detection system (such as detection system 164) compensates for the intensity drift by using a reference to improve signal stability and SNR. Graph 500 includes two axes. A horizontal axis 510 labeled "Time" shows increasing time from t0 on the left side of the graph to t+n on the right side of the graph. A vertical axis 520 labeled "Intensity" shows intensity values, which show increasing intensity near point 522 above and decreasing intensity near point 522 below. Graph 500 includes two plotted trend lines, a first trend line 502 and a second trend line 504. First trend line 502 illustrates the intensity drift of an example light source (e.g., light source 166) over time. Observing first trend line 502, it is shown that initially, the intensity of the light source begins with a sharp increase in intensity 502a, followed by a sharp decrease in intensity 502b. Shortly thereafter, the intensity decrease begins a gradual ramp, 502c, and reaches a semi-continuous intensity 502d. This change in intensity over time creates problems for detection systems. Without a reference, such as shown by first trend line 502, a measurement taken at one point in time cannot be reliably compared to a measurement taken at a later point in time because changing intensity inherently changes the measured value. Second trend line 504 shows the intensity drift of an example light source (e.g., light source 166) over time, and is referenced by detection system 164. Using a reference, the sharp increase and decrease in first trend line 502 are replaced by a damped rise 504a followed by a constant intensity value 504b. Using a reference normalizes the intensity of the light source and improves the SNR. FIG5B illustrates a graph 550 titled "Multi-Wavelength Reference," which shows the improvement in SNR at multiple wavelengths of light achieved by referencing in detection system 164. Graph 550 includes two axes. Horizontal axis 510, labeled "Intensity," shows the intensity of various light sources at different wavelengths from the left side of graph 550 to the right side of graph 550. Vertical axis 520, labeled "SNR," plots the improvement in signal-to-noise ratio. Graph 550 includes two plotted areas, a first area 552 without a reference and a second area 554 with a reference. First area 552 shows that without a reference, as lamp intensity increases, there is a small improvement in SNR across multiple wavelengths of light. Second area 554 shows that with a reference, detection system 164 as described herein can improve SNR across multiple wavelengths of light. FIG6 is a flow chart of a method 600 for emitting and collecting reflected light within a processing chamber according to one embodiment of the present disclosure. Method 600 may be understood with reference to FIG4 and FIG4A-4B. FIG6 includes a simplified version of the claimed subject matter and is not intended to limit the present disclosure. Operation 610 of method 600 includes transmitting a first portion of an incident light beam to at least a region of a substrate 120 disposed within a processing chamber 100 . Operation 610 of method 600 may include transmitting the incident light beam 176 from the light source 166 to the beam splitter 172 via the fiber optic bundle 310 including at least a first optical fiber. Operation 610 of method 600 may include transmitting at least a sub-portion of the incident light beam 176 from at least a first sub-region of the light source 166 to the at least first optical fiber, and receiving at least the sub-portion of the incident light beam 176 from the at least first optical fiber at the beam splitter 172. Operation 610 of method 600 may include transmitting a first portion of the incident light beam 176 from the beam splitter 172 to the lens assembly 168 via the optical fiber bundle 310. Operation 610 of method 600 may include splitting at least a subportion of the incident light beam 176 into at least a first subportion of incident light, wherein the at least first subportion of incident light corresponds to at least a first subregion of the light source 166, returning the at least first subportion of the incident light from the beam splitter 172 to at least a first optical fiber, and transmitting the at least first subportion of the incident light from the at least first optical fiber to the lens assembly 168. Operation 610 of method 600 may include focusing a first portion of the incident light beam 176 as incident light rays from the lens assembly 168 onto at least one region of a substrate 120 disposed within the processing chamber 100. Operation 610 of method 600 may include receiving at least a first sub-portion of the incident light beam 176 from the beam splitter 172 via the fiber optic bundle 310, and focusing at least the first sub-portion of the incident light beam 176 as incident light rays 236 from the lens assembly 168 onto at least one region of the substrate 120. Operation 620 of method 600 includes transmitting a second portion of the incident light beam 176 to the detection system 164 as the reference beam 206 . Operation 620 of method 600 may include transmitting the second portion of the incident light beam 176 from the beam splitter 172 to the detection system 164 as the reference beam 206 via a return fiber bundle 312 including at least one return fiber. Operation 620 of method 600 may include splitting at least a subportion of the incident light beam 176 into at least a second subportion of the incident light, wherein the at least second subportion of the incident light corresponds to at least the first subregion of the light source 166, transmitting at least the second subportion of the incident light from the beam splitter 172 to at least the first return optical fiber for transmission to the detection system 164 as at least the first subportion of the reference beam 206, and receiving at least the first subportion of the reference beam 206 from the at least first return optical fiber at the detection system 164, wherein the at least first subportion of the reference beam 206 corresponds to at least the first subregion of the light source 166. Operation 630 of method 600 includes receiving, at the detection system 164 , a first portion of the incident light beam 176 from at least one area of ​​the substrate 120 as a reflected light beam 178 . Operation 630 of method 600 may include receiving reflected light 240 from at least one area of ​​substrate 120 at lens assembly 168, transmitting the reflected light 240 as at least a first sub-portion of reflected light beam 178 from lens assembly 168 to at least a first optical fiber of optical fiber bundle 310, transmitting the reflected light 240 as reflected light beam 178 from lens assembly 168 to beam splitter 172 via optical fiber bundle 310, and transmitting the reflected light beam 178 from beam splitter 172 to detection system 164 via return optical fiber bundle 312. Operation 630 of method 600 may include receiving reflected light 240 from at least one region of substrate 120 at lens assembly 168 and transmitting reflected light 240 from lens assembly 168 to at least a first optical fiber as at least a first sub-portion of reflected light beam 178 . Operation 640 of method 600 includes determining at least one characteristic of a region of substrate 120 . Operation 640 of method 600 may include receiving at least a first subportion of the reference beam 206, wherein at least the first subportion of the reference beam 206 corresponds to at least a first subregion of the light source 166, receiving at least a first subportion of the reflected beam 178, wherein at least the first subportion of the reflected beam 178 corresponds to at least a first subportion of the incident light, wherein at least the first subportion of the incident light corresponds to at least a first subregion of the light source 166, and referencing the first subportion of the reflected beam 178 to the first subportion of the reference beam 206 to improve a first signal-to-noise ratio (SNR). Operation 640 of method 600 may include analyzing a full spectrum of the reflected light beam 178 based in part on the first SNR, wherein the full spectrum is between approximately 200 nanometers (nm) and approximately 800 nm. Operation 640 of method 600 may include determining, based on the first SNR and analyzing the full spectrum of the reflected light beam 178, at least one height of a feature disposed on at least one region of the substrate 120, at least one size of a feature disposed on at least one region of the substrate 120, at least one wavelength of radiative emission from plasma of at least one region of the substrate 120, at least one intensity of radiative emission from plasma of at least one region of the substrate 120, or a combination thereof. Operation 640 of method 600 may include receiving at least a first subportion of the reference beam 206, wherein the at least first subportion of the reference beam 206 corresponds to at least a first subregion of the light source 166, receiving at least a second subportion of the reference beam 206, wherein the at least second subportion of the reference beam 206 corresponds to at least the second subregion of the light source 166, receiving at least a first subportion of the reflected beam 178 from at least the first region of the substrate 120, wherein the at least first subportion of the reflected beam 178 corresponds to at least a first subportion of the incident light, wherein the at least first subportion of the incident light corresponds to The subportion corresponds to at least a first subportion of the light source 166, receives at least a second subportion of the reflected light beam 178 from at least a second region of the substrate 120, wherein at least the second subportion of the reflected light beam 178 corresponds to at least a second subportion of the incident light, wherein at least the second subportion of the incident light corresponds to at least the second subportion of the light source 166, references the first subportion of the reflected light beam 178 to the first subportion of the reference beam 206 to improve the first SNR, and references the second subportion of the reflected light beam 178 to the second subportion of the reference beam 206 to improve the second SNR. Operation 640 of method 600 may include analyzing a full spectrum of at least a first sub-portion of the reflected light beam 178 based in part on the first SNR, wherein the full spectrum is between approximately 200 nanometers (nm) and approximately 800 nm, and analyzing a full spectrum of at least a second sub-portion of the reflected light beam 178 based in part on the second SNR, wherein the full spectrum is between approximately 200 nanometers (nm) and approximately 800 nm. Operation 640 of method 600 may include determining at least one characteristic of at least the first region of the substrate 120 based on the improved first SNR and analyzing the full spectrum of at least the first sub-portion of the reflected light beam 178, wherein determining the at least one characteristic further comprises determining: at least one height of a feature disposed on at least the first region of the substrate 120, at least one size of a feature disposed on at least the first region of the substrate 120, at least one wavelength of radiative emission from the plasma of at least the first region of the substrate, at least one intensity of radiative emission from the plasma of at least the first region of the substrate 120, or a combination thereof, based on the improved first SNR and analyzing the full spectrum of at least a second sub-portion of the reflected light beam 178. to determine at least one characteristic of at least the second region of the substrate 120, wherein determining the at least one characteristic further includes determining: at least one height of a feature disposed on the at least second region of the substrate 120, at least one size of a feature disposed on the at least second region of the substrate 120, at least one wavelength of radiation emission from the plasma of the at least second region of the substrate 120, at least one intensity of radiation emission from the plasma of the at least second region of the substrate 120, or a combination thereof, and comparing the at least one characteristic of the at least first region of the substrate 120 with the at least one characteristic of the at least second region of the substrate 120 to improve the detection density of the at least one characteristic of the at least second region of the substrate 120. Operation 560 of method 600 includes repeating previous operations, ie, operation 610 , operation 620 , operation 630 , and / or operation 640 , as needed until the measurement and analysis of the substrate 120 is complete. Additional considerations Although this specification contains many specific implementation details, these should not be construed as limitations on the scope of what may be claimed, but rather as descriptions of features that may be specific to particular implementations. Certain features described in this specification in the context of separate implementations may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented separately in multiple implementations or in any suitable subcombination. Furthermore, although previously described features may be described as functioning in certain combinations and even initially claimed as such, in some cases one or more features from a claimed combination may be deleted from that combination, and the claimed combination may be directed to subcombinations or variations of subcombinations. Specific embodiments of the subject matter have been described. Other embodiments, modifications, and permutations of the described embodiments are within the scope of the appended claims, as will be apparent to those skilled in the art. Although operations are depicted in a particular order in the drawings or claims, this should not be construed as requiring that such operations be performed in the particular order shown, or in a sequential order, or that all illustrated operations (some operations may be considered optional) be performed in order to achieve the desired results. In certain circumstances, multitasking or parallel processing (or a combination of multitasking and parallel processing) may be advantageous and should be performed as deemed appropriate. In addition, the separation or integration of the various system modules and components in the previously described embodiments should not be understood as requiring such separation or integration in all embodiments. It should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. Thus, the exemplary embodiments described above do not define or limit the present disclosure. Other changes, substitutions, and alterations are possible without departing from the spirit and scope of the present disclosure. Although the various steps in the example methods or processes are presented and described sequentially, those skilled in the art will appreciate that some or all of the steps may be performed in a different order, combined, or omitted, and that some or all of the steps may be performed in parallel. Steps may be performed actively or passively. The methods or processes may be repeated or expanded to support multiple components or multiple users within a field environment. Thus, the scope should not be considered limited to the specific arrangement of steps shown in the flowcharts or diagrams. Unless defined otherwise, all technical and scientific terms used have the same meaning as commonly understood by one of ordinary skill in the art to which these systems, apparatuses, methods, processes, and compositions belong. In this disclosure, the terms "top," "bottom," "side," "above," "below," "up," "down," "upward," "downward," "horizontal," "vertical," and the like do not refer to absolute directions. Instead, these terms refer to directions relative to a non-specific reference plane. This non-specific reference plane can be vertical, horizontal, or oriented at other angles. Unless the context clearly dictates otherwise, the singular forms "a," "an," and "the" include plural references. Within the claims, reference to an element in the singular is not intended to mean "one and only one," unless specifically stated otherwise, but rather "one or more." The term "some" refers to one or more unless specifically stated otherwise. The disclosed embodiments may suitably "consist of," "consist of," or "consist essentially of" the disclosed limitations, and may be practiced without undisclosed limitations. As used herein and in the appended claims, the words "comprising," "having," and "including," and all grammatical variations thereof, are intended to have an open, non-limiting meaning that does not exclude additional elements or steps. "Optional" and "subject to change" mean that the subsequently described material, event, or circumstance may or may not occur. The description includes instances where the material, event, or circumstance occurs and instances where it does not. As used, the term "determine" encompasses a wide variety of actions. For example, "determine" can include calculating, computing, processing, deriving, investigating, searching (e.g., searching in a table, database, or another data structure), and validating. Furthermore, "determine" can include receiving (e.g., receiving information) and accessing (e.g., accessing data in memory). Furthermore, "determine" can include solving, selecting, choosing, and establishing. When the word "about" or "approximately" is used, the term may mean that the value may vary by up to ±10%, up to 5%, up to 2%, up to 1%, up to 0.5%, up to 0.1%, or up to 0.1%. Ranges can be expressed as from about one particular value to about another particular value, inclusive. When such a range is expressed, it will be understood that another embodiment is from the one particular value to the other particular value, along with all particular values ​​within the range and combinations thereof. As used, terms such as "first" and "second" are arbitrarily designated and are intended solely to distinguish between two or more components of a system, apparatus, or composition. It will be understood that the terms "first" and "second" have no other purpose and are not part of the names or descriptions of the components, nor do they necessarily define the relative positioning or positions of the components. Furthermore, it will be understood that the mere use of the terms "first" and "second" does not require the presence of any "third" component, although that possibility is contemplated within the scope of the various embodiments described. As used herein, "CPU," "processor," "at least one processor," or "one or more processors" generally refers to a single processor configured to perform one or more operations or multiple processors configured to collectively perform one or more operations. In the case of multiple processors, the performance of one or more operations may be divided among different processors, although a single processor may perform multiple operations and multiple processors may collectively perform a single operation. Similarly, "memory," "at least one memory," or "one or more memories" generally refers to a single memory configured to store data and / or instructions or multiple memories configured to collectively store data and / or instructions. Although only a few exemplary embodiments have been described in detail, those skilled in the art will readily appreciate that many modifications of the exemplary embodiments are possible without materially departing from the scope of the disclosure described. Accordingly, all such modifications are intended to be included within the scope of the disclosure, as defined in the following claims. 100: Processing chamber 102: Chamber body 103: Top plate 104: Fiber bundle 107: Chamber bottom 114: Internal volume 116: Substrate support 120: Substrate 121: Surface 122: Gas distributor 125: Electrode power supply 126: Induction coil 127: Coil power supply 128: Network 130: Exhaust system 132: Throttle valve 134: Exhaust port 135: Network 148: Process gas source 150: Controller 152: CPU 154: Memory 156: Support Circuitry 158: Connections 164: Detection System 166: Light Source 168: Lens Assembly 170: Light Detector 172: Beam Splitter 174: Focusing Lens 174a: Focusing Lens 174b: Focusing Lens 176: Incident Light Beam 178: Reflected Light Beam 180: Beam Spot 182: Lens Window 186: Reflector 188: Substrate Support Surface 206: Reference Beam 208: Return Fiber Optic Bundle 236: Incident Light 240: Reflected Light 242: Substrate Image Size 252: Lens distance 254: Substrate distance 260: Initial spot size 264: Fiber bundle exit 302: Fiber 310: Fiber bundle 500: Graph 502: First trend line 502A: Intensity 502B: Intensity 504: Second trend line 504A: Rising 504B: Constant intensity value 510: Horizontal axis 520: Vertical axis 522: Points 550: Graph 552: First region 554: Second region 560: Operation 600: Method 610: Operation 620: Operation 630: Operation 640: Operation In order that the manner in which the above-described features of the present disclosure can be understood in detail, a more particular description of the present disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the accompanying drawings. It will be noted, however, that the drawings illustrate only exemplary embodiments and are not to be considered limiting of its scope, as other equally effective embodiments may be admitted. FIG. 1 is a schematic cross-sectional view of an example plasma processing chamber with a detection system according to one example of the present disclosure. FIG. 2 is a schematic cross-sectional view of an example of a collimated optical path with a fiber optic bundle configured to transmit and receive light in a processing chamber, as commonly employed in the prior art. 3 is an example schematic cross-sectional diagram of the light path of a single optical fiber configured to transmit and receive light in a processing chamber according to one example of the present disclosure. 4 is a schematic cross-sectional view of a fiber optic bundle design and light paths having a fiber optic bundle configured to transmit and receive light in a processing chamber according to one example of the present disclosure. 4A is a cross-sectional view of an outlet of a fiber optic bundle configured to transmit and receive light in a processing chamber according to one example of the present disclosure. FIG. 4B is an example cross-sectional view of light beams transmitted from a plurality of optical fibers in a receive state and reflected at a substrate surface according to one example of the present disclosure. FIG. 5A shows a graph of a single wavelength reference according to one example of the present disclosure. FIG. 5B shows a graph of a multi-wavelength reference according to one example of the present disclosure. FIG. 6 is a flow chart of a method for emitting and collecting reflected light within a processing chamber according to one example of the present disclosure. To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. Domestic deposit information (please note in the order of deposit organization, date, and number) None Foreign deposit information (please note in the order of deposit country, organization, date, and number) None 100: Processing chamber 102: Chamber body 103: Top plate 104: Fiber optic bundle 107: Chamber bottom 114: Internal volume 116: substrate support 120:Substrate 121: Surface 122: Gas distributor 125: Electrode power supply 126: Induction coil 127: Coil power supply 128: Internet 130: Exhaust system 132: Throttle valve 134: Discharge Port 135: Internet 148: Processing gas source 150:Controller 152:CPU 154:Memory 156: Support circuit 158: Wiring 164:Detection System 166: Light Source 168: Lens assembly 170:Light Detector 172: Optical Splitter 174: Focusing lens 174a: Focusing lens 174b: Focusing lens 176: Incident beam 178:Reflected beam 180: beam spot 182: Lens window 186: Reflector 188: substrate support surface

Claims

1. An optical reflectance measurement system, comprising: a processing chamber having a top plate, sidewalls, and a bottom defining an internal volume, wherein the top plate includes a transparent window; a substrate support located within the internal volume, wherein the substrate support is configured to receive a substrate; a light source located outside the internal volume and configured to transmit an incident light beam; an optical fiber bundle located outside the internal volume, including at least one first optical fiber coupled to the light source and optically coupled to a lens assembly, wherein the lens assembly is disposed above the transparent window and optically coupled to at least the first optical fiber, and configured to: transmit the incident light beam as incident light through the transparent window to at least one region of the substrate; receive reflected light from the at least one region of the substrate through the transparent window; and transmit the reflected light as a reflected light beam to the optical fiber bundle; a beam splitter disposed within the optical fiber bundle; and a return optical fiber bundle including at least one first return optical fiber coupled to the beam splitter and coupled to a detection system, wherein the detection system is configured to: A reference beam and the reflected beam are referenced to improve a signal-to-noise ratio (SNR), a full spectrum of the reflected beam is analyzed in part based on the SNR, and at least one characteristic of at least one region of the substrate is determined based on the analysis.

2. The optical reflectance measurement system as claimed in claim 1, wherein the full spectrum is between 200 nanometers (nm) and 800 nm.

3. The optical reflection measurement system of claim 1, wherein the at least one characteristic of the at least one region of the substrate comprises: at least one height of a feature disposed in the at least one region of the substrate; at least one size of a feature disposed in the at least one region of the substrate; at least one wavelength of radiation emission from a plasma of the at least one region of the substrate; at least one intensity of radiation emission from the plasma of the at least one region of the substrate; or a combination thereof.

4. The optical reflectance measurement system as claimed in claim 1, wherein the light source is a monochromatic light source.

5. The optical reflectance measurement system as claimed in claim 1, wherein the light source is a multicolor light source.

6. The optical reflection measurement system of claim 1, wherein the at least the first optical fiber is configured to: receive at least a sub-portion of the incident beam from at least a first sub-region of the light source; transmit at least the sub-portion of the incident beam; receive at least the sub-portion of the reflected beam; and transmit at least the sub-portion of the reflected beam.

7. The optical reflection measurement system as claimed in claim 1, wherein at least the first optical fiber has a diameter between 0.1 mm and 0.5 mm.

8. The optical reflection measurement system as claimed in claim 1, wherein a region of the at least one region of the substrate has a substrate image size with a diameter between 0.1 mm and 10 mm.

9. The optical reflection measurement system of claim 1, wherein at least the first return fiber is configured to: receive at least a sub-portion of the reference beam; transmit at least the sub-portion of the reference beam; receive at least a first sub-portion of the reflected beam; and transmit at least the sub-portion of the reflected beam.

10. The optical reflection measurement system of claim 1, wherein the beam splitter is configured to: receive at least one sub-part of the incident beam from the at least first optical fiber; divide the at least one sub-part of the incident beam into at least one first sub-part of incident light and at least one second sub-part of incident light; transmit the at least one first sub-part of incident light to the at least first optical fiber; transmit the at least one second sub-part of incident light to the at least first return optical fiber as at least one sub-part of the reference beam; receive at least one sub-part of the reflected beam; and transmit the at least one sub-part of the reflected beam to the at least one second return optical fiber.

11. The optical reflection measurement system of claim 1, wherein the lens assembly includes at least one focusing lens, and the lens assembly is configured to: receive at least a first sub-portion of incident light from the at least first optical fiber; focus the at least one first sub-portion of the incident light onto at least one region of the substrate; receive reflected light from at least one region of the substrate; and transmit the reflected light as at least a first sub-portion of the reflected beam to the at least first optical fiber.

12. The optical reflection measurement system of claim 11, wherein the at least one region of the substrate has a substrate image size diameter between 0.1 mm and 10 mm.

13. The optical reflectance measurement system of claim 1, wherein the detection system includes a spectral reflectance measurement system further configured to: receive at least a sub-portion of the reference beam, wherein the at least a sub-portion of the reference beam corresponds to at least a first sub-region of the light source; and receive at least a sub-portion of the reflected beam, wherein the at least a sub-portion of the reflected beam corresponds to at least the first sub-region of the light source.

14. A method for measuring optical reflectance, comprising the steps of: transmitting an incident beam from a light source to a beam splitter via an optical fiber bundle including at least one first optical fiber; transmitting a first portion of the incident beam from the beam splitter to a lens assembly via the optical fiber bundle; transmitting a second portion of the incident beam as a reference beam from the beam splitter to a detection system via a return optical fiber bundle including at least one return optical fiber; focusing the first portion of the incident beam as incident light from the lens assembly onto at least one region of a substrate disposed within a processing chamber; receiving reflected light from the at least one region of the substrate at the lens assembly; transmitting the reflected light as a reflected beam from the lens assembly to the beam splitter via the optical fiber bundle; transmitting the reflected beam from the beam splitter to the detection system via the return optical fiber bundle; referencing the reflected beam to the reference beam to improve a signal-to-noise ratio (SNR); analyzing a full spectrum of the reflected beam in part based on the improved SNR; and determining at least one characteristic of the at least one region of the substrate based on the analysis.

15. The method of claim 14, wherein the step of transmitting the incident beam from the light source to the beam splitter further comprises the steps of: transmitting at least a sub-portion of the incident beam from at least a first sub-region of the light source to the at least the first optical fiber; and receiving the at least a sub-portion of the incident beam from the at least the first optical fiber at the beam splitter.

16. The method of claim 14, wherein the step of transmitting the first portion of the incident beam from the beam splitter to the lens assembly further comprises the following steps: dividing at least one sub-portion of the incident beam into at least one first sub-portion of incident light, wherein the at least one first sub-portion of incident light corresponds to at least one first sub-region of the light source; returning the at least one first sub-portion of incident light from the beam splitter to the at least one first optical fiber; and transmitting the at least one first sub-portion of incident light from the at least one first optical fiber to the lens assembly.

17. The method of claim 14, wherein the step of transmitting the second portion of the incident beam as the reference beam from the beam splitter to the detection system further comprises the following steps: dividing at least one sub-portion of the incident beam into at least one second sub-portion of the incident light, wherein the at least one second sub-portion of the incident light corresponds to at least one first sub-region of the light source; transmitting the at least one second sub-portion of the incident light from the beam splitter to at least one first return fiber as at least one first sub-portion of the reference beam; and receiving at the detection system the at least one first sub-portion of the reference beam from at least the first return fiber, wherein the at least one first sub-portion of the reference beam corresponds to the at least one first sub-region of the light source.

18. The method of claim 14, wherein the step of focusing the first portion of the incident beam as incident light from the lens assembly onto at least one region of a substrate disposed within a processing chamber further comprises the steps of: receiving at least a first sub-portion of the incident beam from the beam splitter via the fiber bundle; and focusing the at least one first sub-portion of the incident beam as incident light from the lens assembly onto at least one region of the substrate.

19. The method of claim 14, wherein the step of transmitting the reflected light rays as a reflected beam from the lens assembly to the beam splitter via the fiber bundle further comprises the steps of: receiving the reflected light rays from at least one region of the substrate at the lens assembly; and transmitting the reflected light rays as at least a first sub-part of the reflected beam from the lens assembly to at least the first fiber.

20. The method of claim 14, wherein the step of referencing the reflected beam to the reference beam to improve the signal-to-noise ratio further comprises the steps of: receiving at least a first sub-portion of the reference beam, wherein the at least one first sub-portion of the reference beam corresponds to at least a first sub-region of the light source; receiving at least a first sub-portion of the reflected beam, wherein at least the first sub-portion of the reflected beam corresponds to at least a first sub-portion of the incident light, wherein the at least one first sub-portion of the incident light corresponds to at least the first sub-region of the light source; and referencing the first sub-portion of the reflected beam to the first sub-portion of the reference beam to improve a first signal-to-noise ratio (SNR).

21. The method of claim 14, wherein the step of analyzing a full spectrum of the reflected beam in part based on the improved SNR further comprises the step of: analyzing a full spectrum of at least a first sub-portion of the reflected beam in part based on a first signal-to-noise ratio (SNR), wherein the full spectrum is between 200 nanometers (nm) and 800 nm.

22. The method of claim 14, wherein the step of determining at least one characteristic of the at least one region of the substrate further comprises the steps of: determining, based on a first signal-to-noise ratio (SNR) and analyzing a full spectrum of the reflected beam: at least one height of a feature disposed on the at least one region of the substrate; at least one size of a feature disposed on the at least one region of the substrate; at least one wavelength of a radiative emission from a plasma of the at least one region of the substrate; at least one intensity of the radiative emission from the plasma of the at least one region of the substrate; or a combination thereof.

23. The method of claim 14, wherein the step of referencing the reflected beam to the reference beam to improve the signal-to-noise ratio (SNR) further comprises the following steps: receiving at least a first sub-portion of the reference beam, wherein the at least one first sub-portion of the reference beam corresponds to at least a first sub-region of the light source; receiving at least a second sub-portion of the reference beam, wherein the at least one second sub-portion of the reference beam corresponds to at least a second sub-region of the light source; receiving at least a first sub-portion of the reflected beam from at least a first region of the substrate, wherein the at least first sub-portion of the reflected beam corresponds to at least a first sub-portion of incident light, wherein the at least first sub-portion of the incident light corresponds to at least the first sub-region of the light source; receiving at least a second sub-portion of the reflected beam from at least a second region of the substrate, wherein the at least second sub-portion of the reflected beam corresponds to at least a second sub-portion of incident light, wherein the at least second sub-portion of the incident light corresponds to at least the second sub-region of the light source; The first sub-part of the reflected beam is referenced to the first sub-part of the reference beam to improve a first SNR; and the second sub-part of the reflected beam is referenced to the second sub-part of the reference beam to improve a second SNR.

24. The method of claim 14, wherein the step of analyzing a full spectrum of the reflected beam in part based on the improved SNR further comprises the steps of: analyzing a full spectrum of at least a first sub-portion of the reflected beam in part based on a first signal-to-noise ratio (SNR), wherein the full spectrum is between 200 nm and 800 nm; and analyzing a full spectrum of at least a second sub-portion of the reflected beam in part based on a second SNR, wherein the full spectrum is between 200 nm and 800 nm.

25. The method of claim 14, wherein the step of determining at least one characteristic of the at least one region of the substrate based on the analysis further comprises the steps of: determining at least one characteristic of the at least one first region of the substrate based on an improved first SNR and analyzing a full spectrum of at least a first sub-portion of the reflected beam, wherein the step of determining the at least one characteristic further comprises determining: at least one height of a feature disposed on at least the first region of the substrate; at least one size of a feature disposed on at least the first region of the substrate; at least one wavelength of a radiation emission from a plasma of at least the first region of the substrate; at least one intensity of the radiation emission from the plasma of at least the first region of the substrate; or a combination thereof; determining at least one characteristic of the at least one second region of the substrate based on an improved second SNR and analyzing a full spectrum of at least a second sub-portion of the reflected beam, wherein the step of determining the at least one characteristic further comprises determining: at least one height of a feature disposed on at least the second region of the substrate; At least one dimension of a feature disposed on at least the second region of the substrate; at least one wavelength of radiation emission from a plasma from at least the second region of the substrate; at least one intensity of radiation emission from the plasma from at least the second region of the substrate; or a combination thereof; And to compare at least one characteristic of at least the first region of the substrate with at least one characteristic of at least the second region of the substrate to improve the detection density of at least one characteristic of at least the second region of the substrate.

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