In-situ optical sensors for chamber surfaces and processes

Abstract

To provide a system and a method, for realizing an in-situ (current site) optical sensor in order to monitor a chamber surface state and a chamber processing parameter.SOLUTION: In a processing tool 100, an optical sensor 120 includes: a housing (a first housing 124 and a second housing 122); and a light path through each housing. The light path includes a first end part and a second end part, in which a reflector 121 is positioned at the first end part of the light path, and a lens 125 is positioned between the reflector and the second end part of the light path. The first housing 124 extends through an open part of a chamber 105 and extends into the chamber interior space, and an extension part such as a pipe 126 passes through the open part of the chamber 105. One or more open parts 123 are arranged along a long direction of the pipe 126, and allow an entry of an electromagnetic emission from the plasma 107 into the optical sensor 120.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Non-provisional Application No. 16 / 378,271, filed April 8, 2019, the entire contents of which are incorporated herein by reference.

[0002] FIELD OF THE DISCLOSURE

[0002] Embodiments relate to the field of semiconductor manufacturing, and more particularly to systems and methods for providing in-situ optical sensors for monitoring chamber surface conditions and chamber processing parameters. [Background technology]

[0003] Changes in the chamber's surfaces affect various process parameters. For example, redeposition of etch by-products on the chamber walls can alter the etch rate of a given process. Thus, when substrates are processed in the chamber, the etch rate (or other process parameters) can change, resulting in non-uniform processing from substrate to substrate.

[0004] Optical emission spectroscopy (OES) has been performed in process chambers in an attempt to describe changes in process conditions. OES involves monitoring the emission spectrum of the plasma in the chamber. Windows are placed along the chamber walls, allowing the emission spectrum to travel along an optical path, through the windows, and to a sensor outside the chamber. When the spectrum of the plasma is changing, a qualitative analysis of the process step can be inferred. In particular, OES helps determine when the end point of the process step has been reached. To provide the best measurements, the windows are designed to prevent deposition from occurring along the optical path. Furthermore, while end point analysis is possible, there is currently no process for performing quantitative analysis using existing OES systems. Summary of the Invention

[0005]

[0005] Embodiments disclosed herein include optical sensor systems and methods of using such systems. In one embodiment, the optical sensor system comprises a housing and an optical path through the housing. In one embodiment, the optical path includes a first end and a second end. In one embodiment, a reflector is at the first end of the optical path and a lens is between the reflector and the second end of the optical path. In one embodiment, the optical sensor further includes an opening through the housing between the lens and the reflector.

[0006] In one embodiment, a method for measuring process or chamber conditions in a processing chamber using an optical sensor includes acquiring a reference signal. In one embodiment, acquiring the reference signal includes emitting electromagnetic radiation from a source outside the chamber, where the electromagnetic radiation propagates along an optical path between the source and a reflector in the chamber, reflecting the electromagnetic radiation along the optical path with the reflector, and sensing the reflected electromagnetic radiation with a sensor optically coupled to the optical path. In one embodiment, the method further includes acquiring a process signal, where acquiring the process signal includes sensing the emitted electromagnetic radiation in the processing chamber traveling along the optical path with the sensor. In one embodiment, the method further includes comparing the process signal to the reference signal.

[0007] In one embodiment, an optical sensing array for a plasma processing chamber includes a plurality of optical sensing systems oriented around the processing chamber, each of the plurality of optical sensing systems comprising a housing, an optical path through the housing, the optical path including a first end and a second end, a reflector at the first end of the optical path, a lens between the reflector and the second end of the optical path, and an opening through the housing between the lens and the reflector. [Brief description of the drawings]

[0008] [Figure 1] 1 illustrates a cross-sectional view of a chamber with an optical sensor penetrating a wall of the chamber, according to one embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of a perspective view of a sensor housing according to one embodiment. [Figure 3A] FIG. 13 is a cross-sectional view of an optical sensor penetrating a chamber wall, showing the light path through the sensor housing, according to one embodiment. [Figure 3B] 2 is a cross-sectional view of an optical sensor after a layer of material has been deposited on a reflector, according to one embodiment. [Figure 4A] 1 is a cross-sectional view of an optical sensor in which the source and sensor are integrated into a sensor housing, according to one embodiment. [Figure 4B] 1 is a cross-sectional view of an optical sensor with a filter along the optical path according to one embodiment. [Diagram 5] FIG. 2 illustrates a top view of a processing chamber with an array of optical sensors penetrating the chamber wall, according to one embodiment. [Figure 6A] FIG. 1 is a process flow diagram illustrating a process for using an optical sensor to determine wall or process conditions, according to one embodiment. [Figure 6B] FIG. 1 is a process flow diagram illustrating a process for obtaining a reference signal, according to one embodiment. [Figure 7] FIG. 1 shows a block diagram of an exemplary computer system that may be used in combination with an optical sensor having an optical path that passes through a chamber wall, according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The systems and methods described herein include optical sensors for in-situ monitoring of chamber conditions and / or process conditions within the chamber. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. It will be apparent to one of ordinary skill in the art that the embodiments may be practiced without these specific details. In other instances, well-known aspects have not been described in detail so as not to unnecessarily obscure the embodiments. Additionally, it should be understood that the various embodiments illustrated in the accompanying drawings are illustrative representations and are not necessarily drawn to scale.

[0010] As noted above, currently available optical emission spectroscopy (OES) systems can provide qualitative measurements to achieve functions such as end point determination, but currently cannot provide accurate quantitative measurements. Process parameters such as etch rate cannot be directly measured with existing OES systems. Thus, embodiments disclosed herein include an optical sensor system that includes an optical path through which both a reference signal and a plasma optical emission spectrum pass. For example, the optical path may start from an optical source, pass through a chamber wall, reflect off a reflector surface within the chamber, and return toward a sensor along the optical path. Because the reference signal and the optical emission spectrum travel along the same optical path, the reference signal can be used to determine losses due to the optical path without opening the chamber and interrupting operation. This allows for accurate, quantitative measurements of the optical emission spectrum. Thus, the calibrated plasma optical emission spectrum can be used to determine process parameters such as etch rate.

[0011] Additionally, currently available OES systems are designed to prevent deposition along the optical path, while the embodiments disclosed herein include a reflector surface that is exposed to the processing environment. In some embodiments, the reflector surface may be selected to substantially match the inner surface of the chamber. Thus, deposition on the reflector surface is substantially similar to that found on the inner surface of the chamber. The reflector surface interacts with the electromagnetic radiation emitted from the source and can be used to determine properties of the deposited film or transformation of the wall material. For example, absorption of a portion of the spectrum of electromagnetic radiation may be correlated with a particular material composition and / or film thickness.

[0012] Thus, the embodiments disclosed herein enable quantitative in situ measurements of process and / or chamber conditions. Because quantitative measurements are provided by the embodiments disclosed herein, the embodiments may enable chamber matching measurements (i.e., comparison of a single process performed in different chambers). In some embodiments, a single optical sensor may be included in the processing chamber. Other embodiments may include an array of optical sensors disposed around the processing chamber. Such embodiments may enable chamber uniformity data (e.g., plasma uniformity, chamber surface uniformity, etc.) to be obtained. Additionally, such embodiments may also provide an indication of chamber anomalies (e.g., chamber drift).

[0013] 1, a cross-sectional view of a processing tool 100 is shown, according to one embodiment. In one embodiment, the processing tool 100 comprises a chamber 105. For example, the chamber 105 may be suitable for low pressure processing steps. In one embodiment, the processing steps may include generating a plasma 107 in the chamber 105. In one embodiment, a substrate support 108 is located within the chamber 105. The substrate support 108 may be a chuck (e.g., an electrostatic chuck, a vacuum chuck, etc.) or any other suitable support on which one or more substrates may be positioned during processing.

[0014] In one embodiment, the processing tool 100 may include an in-situ optical sensor 120. The in-situ optical sensor 120 penetrates a surface of the chamber 105, with a first portion of the optical sensor 120 inside the chamber 105 and a second portion of the optical sensor outside the chamber 105. In one embodiment, the optical sensor 120 is shown as penetrating a sidewall of the chamber 105. However, it should be understood that the optical sensor 120 may be positioned through any surface of the chamber 105.

[0015] In the illustrated embodiment, a single optical sensor 120 is shown. However, it should be understood that the embodiment is not limited to such a configuration and more than one optical sensor 120 may be included in the processing tool 100. Furthermore, the optical sensor 120 only requires a single optical opening (i.e., a window) through the chamber 105. As described in more detail below, the optical path includes a reflector 121 that reflects the electromagnetic radiation from the source 137 back through the same opening. This is in contrast to existing systems that require an optical path across the interior space of the chamber 105 and require at least two optical openings through the chamber.

[0016] In one embodiment, the optical sensor 120 comprises a housing. In one embodiment, the housing may include a first housing 124 and a second housing 122. In one embodiment, the first housing 124 may be secured to the second housing 122 with any suitable fastener. In other embodiments, the housing may be a unitary structure. That is, the first housing 124 and the second housing 122 may be combined into a single structure. Additionally, while the first housing 124 and the second housing 122 are disclosed, it should be understood that the housing may include any number of components coupled together.

[0017] In one embodiment, the first housing 124 can extend through the opening of the chamber 105 and into the chamber interior space. For example, an extension such as a tube 126 can pass through the opening of the chamber 105. In one embodiment, the tube 126 can be an optically transparent material. For example, the tube 126 can be quartz. However, it should be understood that the tube 126 need not be optically transparent. In some embodiments, the tube 126 can be a ceramic or metallic material. Additionally, while a tube 126 is described, it should be understood that any elongated member can extend into the interior space of the chamber 105. In particular, any structure capable of supporting the reflector 121 within the interior space of the chamber 105 can be used.

[0018] In one embodiment, one or more openings 123 may be disposed along the length of the tube 126. The one or more openings 123 allow electromagnetic radiation from the plasma 107 to enter the optical sensor 120. Additionally, the openings 123 expose the reflector 121 to a processing environment. Exposing the reflector 121 to the processing environment allows the surface of the reflector 121 to be altered in substantially the same manner as the inner surface of the chamber is altered during the processing step. For example, by-products deposited on the inner surface of the chamber 105 may also be deposited on the reflector 121. In certain embodiments, the reflector 121 may include the same material as the inner surface of the chamber 105. Thus, it may be assumed that the changes in the surface of the reflector 121 are substantially consistent with the changes in the inner surface of the chamber 105. In this manner, chamber surface monitoring may be performed by the optical sensor 120.

[0019] In some embodiments, the reflector 121 may be a replaceable component. That is, the reflector 121 may be a removable component from the first housing 124. For example, the reflector 121 may be attached to a lid that covers the end of the tube 126. The use of a removable reflector allows the reflector 121 to be replaced after a usable life. Additionally, different reflector materials may be used to match the interior surfaces of the chambers of various processing tools.

[0020] In some embodiments, a lens 125 may be fixed between the first housing 124 and the second housing 122. The lens 125 is disposed along the optical path between the source 137 and the reflector 121 to focus electromagnetic radiation traveling along the optical path. In some embodiments, the lens 125 may be part of a seal that closes an opening through the chamber 105. For example, an O-ring or the like may be placed on a surface of the lens 125 that faces the chamber 105.

[0021] In one embodiment, the optical sensor 120 may further include a source 137 and a sensor 138. The source 137 and the sensor 138 may be optically coupled to an optical path. For example, a fiber optic cable 132 may extend from the second housing 122. In one embodiment, the fiber optic cable 132 may include a splitter 134 that branches into a fiber optic cable 135 to the source 137 and a fiber optic cable 136 to the sensor 138.

[0022] In one embodiment, source 137 may be any suitable source for propagating electromagnetic radiation along an optical path. In particular, the embodiment includes a precision source 137. Precision source 137 provides a known electromagnetic spectrum that can be used as a reference baseline for making measurements with optical sensor 120. In one embodiment, source 137 may be a single wavelength source. For example, source 137 may be a laser or a light emitting diode (LED). In other embodiments, source 137 may be a broadband light source. For example, source 137 may be an arc flash lamp (e.g., a xenon flash lamp).

[0023] In one embodiment, the sensor 138 may be any suitable sensor for detecting electromagnetic radiation. In one embodiment, the sensor 138 may include a spectrometer. For example, the spectrometer may have a charge-coupled device (CCD) array. In other embodiments, the sensor 138 may have a photodiode that is sensitive to specific wavelengths of electromagnetic radiation.

[0024] 2, a cross-sectional view of a three-dimensional view of the housing of the optical sensor 220 is shown, according to one embodiment. As shown, an optical path 228 extends through the housing. For example, the optical path 228 extends along a channel in the second housing 222, through the lens 225, through the tube 226 in the first housing 224, and toward the reflector 221. In one embodiment, an opening 223 through the tube 226 allows electromagnetic radiation from the processing environment (e.g., from the plasma) to enter the housing and propagate along the optical path 228. The opening 223 also exposes the reflector 221 to the processing environment in the chamber. Thus, deposition or other transformations on the surface of the reflector 221 can be monitored to determine changes to the inner surface of the chamber.

[0025] As shown in Figure 2, the reflector 221 is a cap that is fitted over the end of the tube 226. Thus, the reflector 221 can be replaced by removing the cap and installing a second cap having a second reflector 221. Additionally, Figure 2 shows a channel 227 proximate to the lens 225. In one embodiment, the channel 227 can be sized to receive an O-ring (not shown) that sits against the first housing 224 and the lens 225. Thus, a vacuum seal can be maintained even if there is an opening through the wall of the chamber.

[0026] 1, the housing of the optical sensor 220 may alternatively be comprised of a single component or more than two components (i.e., more than the first housing 224 and the second housing 222). Additionally, the tube 226 may be replaced with any elongated structure capable of supporting a reflector along the optical path 228. For example, the tube 226 may be replaced with one or more beams extending from the first housing 224.

[0027] 3A and 3B, a pair of cross-sectional views illustrates a process for using an optical sensor, according to one embodiment.

[0028] Referring now to FIG. 3A, a cross-sectional view is shown at the start of processing of a substrate. As shown, the optical sensor 320 is substantially similar to the optical sensors 120 and 220 described above. For example, a housing is shown including a first housing 324, a second housing 322, a lens 325, and a reflector 321. The reflector 321 is shown in FIG. 3A as floating; that is, only the opening 323 in the support structure is shown. However, it should be understood that the reflector 321 is connected to the first housing 324 with a structure outside the plane of the cross-sectional view. For example, the reflector 321 can be connected to the first housing 324 using one or more beams or tubes.

[0029] In one embodiment, a reference signal 341 may be generated by a source (not shown) and optically coupled to an optical path through the housings 324, 322. For example, the reference signal 341 may propagate along a fiber optic cable 332 before entering the housing 322. The reference signal 341 may then propagate towards the reflector 321, be reflected, and return along the optical path as a reflected signal 342. The reflected signal 342 may be optically coupled to the fiber optic cable 332 and sent to a sensor (not shown).

[0030] Because the source emits electromagnetic radiation of known spectrum and intensity, the measurement of the reflected signal 342 by the sensor provides a baseline of loss along the optical path. That is, the difference between the measurement (e.g., spectrum and intensity) of the reflected signal 342 and the known spectrum and intensity of the source provides a measure of loss inherent to the optical sensor 320. The known loss can thus be used to calibrate subsequently obtained signals.

[0031] In particular, electromagnetic radiation emitted by the plasma may also be sensed by a sensor. For example, plasma signal 343 may pass through aperture 323 of optical sensor 320 and propagate along an optical path to a sensor (not shown). The measurement of plasma signal 343 may then be corrected by adding back known losses inherent to the optical sensor. In this way, a quantitative measurement of electromagnetic radiation emitted by the plasma may be provided.

[0032] 3B, a cross-sectional view of optical sensor 320 is shown after film 306 has been disposed on the surface of chamber 305 and on the surface of reflector 321, according to one embodiment. In one embodiment, film 306 may be a by-product of a processing step performed in chamber 305. For example, film 306 may be a redeposition of a by-product of an etching process. In an embodiment in which the surface of reflector 321 is the same material as the inner surface of chamber 305, film 306 on reflector 321 would be representative of film 306 on the inner surface of chamber 305.

[0033] Thus, the optical sensor 320 may also be used to determine one or more properties of the film 306. In one embodiment, the reflected signal 342 may be measured to find the difference relative to the reference signal 341. For example, a decrease in a particular wavelength of the reflected signal 342 (compared to the reference signal) may be used to determine what material is deposited on the film. In particular, a particular material will preferentially absorb a portion of the spectrum of the reference signal 341. Thus, by identifying portions of the reflected signal 342 that are decreasing in intensity, it is possible to determine the composition of the film 306. Additionally, the change in the reflected signal 342 may also identify the film thickness.

[0034] 4A, a cross-sectional view of an optical sensor 420 through a surface of the chamber 405 is shown according to an additional embodiment. The optical sensor 420 of FIG. 4A is substantially similar to the optical sensor 320 of FIG. 3A, except that the source 437 and the sensor 438 are directly integrated into the second housing 422. For example, the reference signal 441 may pass through the prism 439 and the lens 425 toward the reflector 421, and the reflected signal 442 and the plasma signal 443 may be redirected by the prism 439 toward the sensor 438. Thus, the optical coupling of the source 437 and the sensor 438 to the optical path may be performed without fiber optic cables. Such an embodiment may also provide a more compact optical sensor 420.

[0035] 4B, a cross-sectional view of an optical sensor 420 through a surface of the chamber 405 is shown according to an additional embodiment. The optical sensor 420 of FIG. 4B is substantially similar to the optical sensor 320 of FIG. 3A, except that a filter 445 is disposed along the optical path. In one embodiment, the filter 445 can provide a specific passband to improve the performance of the optical sensor to improve the signal-to-noise ratio. In one embodiment, the filter 445 is disposed between the lens 425 and the sensor (not shown). That is, the filter 445 is disposed outside the chamber interior space to be protected from the processing environment.

[0036] 5, a top cross-sectional view of a processing tool 500 is shown, according to one embodiment. In one embodiment, the processing tool 500 may include a chamber 505. A substrate support 508 (e.g., a chuck, etc.) may be disposed within the chamber 505. In one embodiment, a plurality of optical sensors 520 may be disposed within the chamber 505. A-E are arranged in an array around the periphery of the chamber 505. A-E may be substantially similar to one or more of the optical sensors described above. In the illustrated embodiment, five optical sensors 520 A-E is shown. However, it should be understood that any number of optical sensors 520 may be included in the processing tool 500. The use of multiple optical sensors 520 allows for uniformity data to be obtained. For example, plasma uniformity and / or wall condition uniformity may be obtained. Additionally, chamber drift may also be determined.

[0037] 6A and 6B, a process flow diagram illustrating a process for using an optical sensor to provide quantitative measurements in situ is shown, according to one embodiment.

[0038] 6A, process 660 begins with step 661, which includes obtaining a reference signal propagated along an optical path between a reflector in the chamber and a sensor outside the chamber. In particular, step 661 may include process 670 shown in FIG. 6B.

[0039] 6B, process 670 may begin at step 671, which includes emitting electromagnetic radiation from a source outside the chamber. In one embodiment, the electromagnetic radiation is propagated along an optical path between the source and a reflector within the chamber. Process 670 may then continue to step 672, which includes reflecting the electromagnetic radiation back along the optical path using the reflector. Process 670 may then continue to step 673, which includes sensing the reflected electromagnetic radiation using a sensor optically coupled to the optical path.

[0040] 6A, the process 660 may then continue to step 662, which includes obtaining a process signal by sensing electromagnetic radiation emitted in the processing chamber and propagated along the optical path. In one embodiment, the process 660 may then continue to step 663, which includes comparing the process signal to a reference signal.

[0041] In one embodiment, the comparison of the reference signal to the process signal may provide a quantitative measurement of the process signal. In particular, the reference signal may provide a measure of losses inherent to the optical sensor. Thus, the losses inherent to the optical sensor may be added back to the process signal to provide a quantitative value of the process signal. Obtaining the quantitative value provides a more accurate understanding of the processing conditions in the chamber. Furthermore, the quantitative value is comparable between different chambers. Thus, chamber matching may be performed to improve process uniformity between different chambers.

[0042] It should be understood that the process steps disclosed in FIG. 6A and FIG. 6B do not have to be performed in any particular order. That is, each signal can be acquired at any time. For example, in one embodiment, the reference signal can be acquired when no process is being performed in the chamber. This provides a reference signal that is not altered by electromagnetic radiation emitted from the plasma. However, it should be understood that in some embodiments, the reference signal can be acquired when the plasma is being generated in the chamber. In other embodiments, the process signal can be acquired when the source is off. In such an embodiment, a pure signal from the plasma can be obtained without interference from the source light. However, it should be understood that in some embodiments, the source light may be on during the measurement of the process signal. Furthermore, it should be understood that one or both of the reference signal and the process signal can be acquired during the processing of one or more substrates in the chamber. As such, the measurements may be referred to as in situ measurements.

[0043] Referring now to FIG. 7, a block diagram of an exemplary computer system 760 of a processing tool is shown, according to one embodiment. In one embodiment, the computer system 760 is coupled to the processing tool and controls processing within the processing tool. The computer system 760 may be connected (e.g., networked) to other machines in a local area network (LAN), an intranet, an extranet, or the Internet. The computer system 760 may operate as a server or a client machine in a client-server network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. The computer system 760 may be a personal computer (PC), a tablet PC, a set-top box (STB), a personal digital assistant (PDA), a mobile phone, a web appliance, a server, a network router, switch, or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be performed by that machine. Furthermore, although only a single machine is illustrated for the computer system 760, the term "machine" shall also be taken to include a collection of machines (e.g., computers) that individually or jointly execute a set (or sets) of instructions to perform any one or more of the methodologies described herein.

[0044] The computer system 760 may include a computer program product or software 722 having a non-transitory machine-readable medium having instructions stored thereon that may be used to program the computer system 760 (or other electronic device) to perform a process according to an embodiment. A machine-readable medium includes any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer). For example, a machine-readable (e.g., computer-readable) medium includes a machine (e.g., computer) readable storage medium (e.g., read-only memory ("ROM"), random access memory ("RAM"), magnetic disk storage media, optical storage media, flash memory devices, etc.), a machine (e.g., computer) readable transmission medium (electrical, optical, acoustic, or other forms of propagated signals (e.g., infrared signals, digital signals, etc.)), etc.

[0045] In one embodiment, computer system 760 includes a system processor 702, a main memory 704 (e.g., read only memory (ROM), flash memory, dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM) or Rambus DRAM (RDMA)), a static memory 706 (e.g., flash memory, static random access memory (SRAM), etc.), and a secondary memory 718 (e.g., a data storage device), which communicate with each other via a bus 730.

[0046] The system processor 702 represents one or more general-purpose processing devices, such as a microsystem processor, a central processing unit, etc. More specifically, the system processor may be a complex instruction set computing (CISC) microsystem processor, a reduced instruction set computing (RISC) microsystem processor, a very long instruction word (VLIW) microsystem processor, a system processor implementing other instruction sets, or a system processor implementing a combination of instruction sets. The system processor 702 may also be one or more special-purpose processing devices, such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal system processor (DSP), a network system processor, etc. The system processor 702 is configured to execute processing logic 726 for performing the operations described herein.

[0047] The computer system 760 may further include a system network interface device 708 for communicating with other devices or machines. The computer system 760 may also include a video display unit 710 (e.g., a liquid crystal display (LDC), a light emitting diode display (LED), or a cathode ray tube (CRT)), an alphanumeric input device 712 (e.g., a keyboard), a cursor control device 714 (e.g., a mouse), and a signal generating device 716 (e.g., a speaker).

[0048] The secondary memory 718 may include a machine-accessible storage medium 731 (or, more specifically, a computer-readable storage medium) having stored thereon one or more sets of instructions (e.g., software 722) embodying any one or more of the methodologies or functions described herein. The software 722 may also reside, completely or at least partially, within the main memory 704 and / or within the system processor 702 during its execution by the computer system 760, with the main memory 704 and the system processor 702 also constituting machine-readable storage media. The software 722 may further be transmitted or received over the network 720 via the system network interface device 708. In one embodiment, the network interface device 708 may operate using RF, optical, acoustic, or inductive coupling.

[0049] While the machine-accessible storage medium 731 is shown to be a single medium in the exemplary embodiment, the term "machine-readable storage medium" should be interpreted to include a single medium or multiple media (e.g., centralized or distributed databases and / or associated caches and servers) that store one or more sets of instructions. The term "machine-readable storage medium" should also be interpreted to include any medium that can store or encode a set of instructions that can be executed by a machine and cause the machine to perform any one or more of the methodologies. Thus, the term "machine-readable storage medium" should be interpreted to include, but is not limited to, solid-state memory, and optical and magnetic media.

[0050] In the foregoing specification, certain exemplary embodiments have been described. It will be apparent that various modifications can be made without departing from the scope of the following claims. The specification and drawings are, therefore, to be regarded in an illustrative rather than a restrictive sense.

Claims

1. 1. A processing tool, comprising: A chamber; an optical sensor system that penetrates the wall of the chamber; The optical sensor system comprises: housing, an optical path through the housing, the optical path including a first end within the chamber and a second end outside the chamber; a reflector at the first end of the optical path; a lens between the second end of the optical path and the reflector; and an opening through the housing between the lens and the reflector, the opening being within the chamber; A processing tool comprising:

2. a light source optically coupled to the lens; and a sensor optically coupled to the lens; The processing tool of claim 1 , further comprising:

3. The processing tool of claim 2 , wherein the light source is a single wavelength source.

4. The processing tool of claim 2 , wherein the light source is a broadband light source.

5. The processing tool of claim 2 , wherein the light source and the sensor are optically coupled to the lens by a fiber optic cable.

6. The processing tool of claim 5 , wherein the fiber optic cable comprises a splitter.

7. The processing tool of claim 2 , further comprising a bandpass filter located along an optical path between the sensor and the aperture.

8. The processing tool of claim 2 , wherein the sensor is a spectrometer or a photodiode.

9. The processing tool of claim 2 , wherein the light source and the sensor are integrated into the housing.

10. The processing tool of claim 1 , wherein the housing is transparent.

11. The processing tool of claim 1 , wherein the reflector is removable.

12. 1. An optical sensing array for a plasma processing chamber, comprising: a plurality of optical sensing systems oriented around the plasma processing chamber, the optical sensing systems penetrating a wall of the plasma processing chamber, each of the plurality of optical sensing systems comprising: a housing extending through the wall of the plasma processing chamber; an optical path through the housing, the optical path including a first end and a second end; a reflector at the first end of the optical path; a lens between the second end of the optical path and the reflector; and an opening through the housing within the plasma processing chamber, the opening being between the lens and the reflector; An optical sensing array comprising:

13. The optical sensing array of claim 12 , wherein the plurality of optical sensing systems are configured to provide uniformity data of plasma conditions, wall conditions, or plasma conditions and wall conditions.

14. The optical sensing array of claim 12 , wherein the plurality of optical sensing systems are configured to provide chamber drift monitoring.

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