Transmission-corrected plasma emission using in-situ optical reflectometry

Abstract

To provide a system including a light source, a light sensor, and a processing device.SOLUTION: The light source directs probing light into the processing chamber through the window for a first period of time. The light source discontinues directing the probing light into the processing chamber through the window for a second period of time. The light sensor detects a first intensity of the first light during the first time period. The first light includes a portion of the probe light reflected from the window and light transmitted through the window from the environment of the processing chamber. The light sensor detects a second intensity of the second light during the second time. The second light includes light transmitted through the window from the environment of the processing chamber. The processing device determines a transmission coefficient of the window using the first intensity and the second intensity.SELECTED DRAWING: Figure 3B

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate generally to the processing of specimens in substrate manufacturing systems, and more particularly to the accuracy of optical measurements performed through windows in the chambers of processing equipment. [Background technology]

[0002] During manufacturing, wafers, substrates, and various other specimens may be processed in special environments, such as the plasma environment during an etching process. The plasma can emit light that can be observed, for example, through a window in the wall of the processing equipment. The observed light can be measured using optical methods, such as optical emission spectroscopy (OES), to monitor the plasma environment and the technological processes performed therein. Summary of the Invention

[0003] Some of the embodiments described herein involve a system including a light source, a light sensor, and a processing device. The light source may be configured to direct a probe light into the processing chamber through a window for a first time and to cease directing the probe light into the processing chamber through the window for a second time. In some embodiments, the light source may be enabled or disabled during separate collection steps. The light sensor may be configured to detect a first intensity of the first light during the first time and a second intensity of the second light during the second time. The first light may include a portion of the probe light reflected from the window and light transmitted through the window from the processing chamber environment, while the second light may include light transmitted through the window from the processing chamber environment. The processing device may be communicatively coupled to the light sensor and configured to determine a transmission coefficient of the window using the first intensity and the second intensity. The processing device may be further configured to determine the intensity of light incident on the window from the processing chamber environment using the second intensity and the transmission coefficient of the window.

[0004] Additional or related embodiments described herein include a system including a processing chamber, an optical sensor, and a processing device. The processing chamber can include a window and plasma gas in the processing chamber environment. The optical sensor can detect a first intensity of a first light including i) a portion of the probe light reflected from the window and ii) light transmitted through the window from the processing chamber environment. The optical sensor can be further configured to detect a second intensity of a second light including light transmitted through the window from the processing chamber environment. The processing device can be communicatively coupled to the optical sensor. The processing device can be configured to determine a transmission coefficient of the window using the first intensity and the second intensity.

[0005] In additional or related embodiments, the processing device can determine the transmission coefficient and / or reflection coefficient of the window by determining the difference between the first intensity and the second intensity. For example, the intensity of the light source can be calibrated to a reference intensity, and the ratio of the difference (between the first intensity and the second intensity) to the reference intensity can be used by the processing device to determine the reflection coefficient of the window. In some embodiments, the reference intensity can be a predetermined reference intensity value. The processing device can then determine the transmission coefficient of the window.

[0006] In further embodiments, the processing device can use the second intensity and the transmission coefficient of the window to determine the intensity of light incident on the window from the processing chamber environment. In particular, after the processing device determines the transmission coefficient, the intensity of light incident on the window can be determined as the ratio between the second intensity and the transmission coefficient. The processing chamber environment can be generated during processing operations performed in the processing chamber, and the processing device can determine the change in the transmission coefficient caused by the processing operation from a reference transmission coefficient of the window. The reference transmission coefficient can be determined in a manner similar to that described above for determining the transmission coefficient, except that the reference transmission coefficient of the window can be determined when the window is new and has not yet been exposed to any processing operations. In some embodiments, the processing chamber environment includes a plasma.

[0007] In additional or related embodiments, the system can further include an optical coupling device for transmitting probe light from the light source to the window. In some embodiments, the optical coupling device can further transmit first light from the window to an optical sensor. The probe light can be incident on the window at an angle approximately perpendicular to the surface of the window. In some embodiments, the system can further include a collimator for directing light generated from the environment so that it is incident approximately perpendicular to the surface of the window. In one embodiment, the probe light can be broadband light and can include a light source, an optical sensor, and a processing device communicatively coupled to the optical sensor. The light source can direct the probe light into the processing chamber through a window of the processing chamber for a first time period and can cease directing the probe light into the processing chamber through the window for a second time period. During the first time period, the optical sensor can detect a first intensity of the first light. The first light can include a portion of the probe light reflected from the window and light transmitted through the window from the environment of the processing chamber. During the second time period, the optical sensor can detect a second intensity of the second light. The second light can include light transmitted through a window from the environment of the processing chamber.

[0008] Numerous other features are provided in accordance with these and other aspects of the present disclosure. Other features and aspects of the present disclosure will become more fully apparent from the following detailed description, the claims, and the accompanying drawings.

[0009] The present disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings, in which like reference designations indicate like elements. It should be noted that different references to "an" or "one" embodiment in this disclosure are not necessarily to the same embodiment, and such references mean at least one. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic top view of an exemplary processing system, according to one embodiment. [Figure 2]FIG. 1 is a simplified side view of a system for optical reflectometry correction, according to one embodiment. [Figure 3A] FIG. 1 is a schematic diagram of a system at an initial stage for a reference measurement for transmission correction of a plasma optical emission signal (OES), according to one embodiment. [Figure 3B] FIG. 1 is a schematic diagram of a system for transmission correction in plasma OES, according to one embodiment. [Figure 4] 1 is a flow diagram of a method for transmission correction in a plasma OES using optical reflectometry measurements, according to one embodiment. In some embodiments, processing logic can be used to perform the method. [Figure 5] FIG. 1 is a block diagram of an example processing device that operates in accordance with one or more aspects of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] The intensity, spectrum, polarization, and other information measured by OES provide valuable data about the manufacturing system environment. For example, the spectral composition of light transmitted through a process chamber window can indicate whether the environment has the appropriate chemical composition. The accuracy of the data provided by OES can be affected by various parameter drifts, which can convolute the measurement signal. For example, the measurement signal can be affected by short-timescale parameter drifts and long-timescale parameter drifts. Short-timescale parameter drifts can be caused by processing operations currently being performed in the process chamber during the manufacturing process. For example, various particles present in the environment can accumulate on the inner surface of the window, affecting its transparency. Such changes can be wavelength-dependent. Longer-timescale parameter drifts can involve more permanent changes to the process chamber window that occur over many manufacturing processes. Such changes can include roughening of the inner surface of the window due to particle bombardment, extraneous deposition, chemical etching, etc. Both types of drifts can convolute the OES signal and degrade the quality of optical monitoring.

[0012] In particular, as processing equipment ages, inefficiencies and / or inaccuracies can arise due to a lack of in-situ information. For example, after process shifts in a processing chamber occur over time, inaccurately measured signals can result in substandard manufacturing output, such as inaccurate deposition amounts (e.g., deposition thickness), inaccurate amounts of material removed (e.g., via etching), inaccurate chemical compositions of deposits, etc. Other processing inefficiencies or inaccuracies can also arise, and are discussed in more detail below.

[0013] The embodiments described herein relate to systems and methods for transmission correction in plasma OES using optical reflectometry and spectroscopy. Optical reflectometry measurement systems may be used in situ, may use optical wall process sensors (OWPS), or may be combined into a single hardware package. Optical reflectometry measurements can be performed on objects located within a processing chamber where conditions and / or process states may change over time. In general, optical reflectometry can be sensitive to the conditions of the environment within the processing chamber and the conditions of the window to the processing chamber. Both types of conditions can be affected by process operations such as deposition, etching (material removal), polishing, etc. Optical reflectometry measurements can be performed through a transparent window in the processing chamber, which can be fabricated from glass, sapphire, quartz, and other suitable materials. The transmission and reflection properties of the transparent window can be affected (e.g., degrade) over time.

[0014] During process operations, properties of / within a processing chamber or the environment hosted therein may change. For example, a processing chamber may contain a plasma or chemical gases, the physical and / or chemical properties of which may passively change or be actively altered during one or more wafer, substrate, or specimen manufacturing processes performed in the chamber. These may be considered short timescale drifts.

[0015] Such drift can affect the plasma OES and, if not accurately measured, can affect the performance and yield of processed substrates. Both the plasma spectrum and optical transparency can drift with the number of substrates processed. The measured OES signal is a convolution of these effects. Understanding the underlying cause of the drift can be difficult due to this convolution. These drifts are sometimes referred to as condition drift because they can be influenced by various conditions, such as the roughness of the inner surface of the process chamber window, the process chamber environment, etc.

[0016] Conventional solutions to the condition drift (parameter drift) problem attempt to minimize the conditions that lead to the drift rather than addressing the drift's impact on the accuracy of optical measurements after the drift has occurred. However, even if condition drift can be reduced, it may not be completely eliminated. Therefore, a measurement technique that is accurate despite the presence of condition drift is needed. Traditionally, optical sensors measure light transmitted from within a processing chamber. Light passed to the optical sensor through a window travels through the environment within the processing chamber (which may include plasma, chemical gases, etc.) as well as through the window itself. As the light passes through the environment, its intensity changes due to scattering, absorption, additional plasma emissions, etc. When the light reaches the window, some of the light is reflected and some of the light is transmitted (e.g., passes through) the window. Therefore, the intensity of the light sensed or measured by the optical sensor depends on both the plasma characteristics and the window characteristics. Surface characteristics of the window, such as degradation or roughening, affect the portion of the transmitted light intensity. Therefore, the effects of the plasma (short-timescale condition drift) and the surface characteristics of the window (long-timescale condition drift) can be difficult to distinguish.

[0017] Aspects and embodiments of the present disclosure include systems and methods that allow for the correction of detected optical signals using optical reflectometry measurements of window properties. Correcting the signal requires understanding the cause of signal drift. The disclosed systems and methods allow for the deconvolution of signal drift caused by changes in the plasma environment from artifactual changes in window properties.

[0018] More specifically, aspects and embodiments of the present disclosure enable deconvolution of the contributions of slow and long-timescale parameter drifts in measured optical reflectometry signals. An optical sensor can be positioned outside a process chamber having a window. Two measurements, namely, an "on" measurement and an "off" measurement, can be performed by the optical sensor. During the "on" measurement, a light source can direct a probe light having a calibrated reference intensity into the process chamber through a window in the process chamber. A portion of the probe light can be transmitted into the process chamber through the window, while another portion of the probe light can be reflected from the window. The optical sensor positioned outside the process chamber measures the reflected intensity. In addition, light can be transmitted through the window from plasma gas in the process chamber. Therefore, during the "on" measurement, the optical sensor measures the "on" intensity, which corresponds to the sum of the intensity of the reflected portion of the probe light and the intensity of the transmitted light originating from the plasma gas.

[0019] On the other hand, during "off" measurements, the light source can be turned off and the light sensor directly detects the transmitted light from the plasma gas, whose intensity depends on the intensity of light incident on the window from the process chamber as the transmission coefficient of the window.

[0020] By using both the "on" and "off" measurements, the contributions of the window and plasma gas conditions to the measured OES signal can be separated. In particular, the transmission coefficient of the window can be extracted by subtracting the measured intensity of the "off" measurement from the measured intensity of the "on" measurement. The transmission coefficient of the window can then be used in conjunction with the measured intensity of the "off" measurement to determine the intensity of light incident on the window from inside the process chamber.

[0021] Additionally, the same measurement may be performed at various times during the life of the processing chamber. Tracking the change in the transmission coefficient over time can allow for separating changes in window properties caused by short-scale processing performed in the chamber from long-scale window degradation caused by multiple processing operations.

[0022] FIG. 1 is a top-view schematic diagram of an exemplary processing system 100 according to one embodiment of the present disclosure. The processing system 100 includes a transfer chamber robot 101 and a factory interface robot 121, each adapted to pick and place substrates 110 (sometimes referred to as “wafers,” “semiconductor wafers,” or specimens) from or to a destination in an electronic device processing system, such as the processing system 100 shown in FIG. 1. However, any type of electronic device substrate, mask, or other silica-containing substrate (generally referred to herein as a “substrate”) can be transported and transferred by the disclosed robot. For example, the destination of the substrate 110 can be one or more processing chambers 103 and / or one or more of load lock apparatuses 107A, 107B distributed around and coupled to the transfer chamber 114. As shown, substrate transfer can be via a slit valve 111, for example.

[0023] The processing system 100 can further include a main frame 102 that includes a transfer chamber 114 and at least two processing chambers 103. The housing of the main frame 102 contains the transfer chamber 114 therein. The transfer chamber 114 can include a top wall (not shown), a bottom wall (floor) 139, and side walls, and in some embodiments can be maintained at a vacuum, for example. In the illustrated embodiment, the transfer chamber robot 101 is mounted to the bottom wall (floor) 139. However, the transfer chamber robot 101 can be mounted elsewhere, such as to the top wall.

[0024] In various embodiments, the processing chamber 103 can be adapted to perform any number of processes on the substrate 110. Processes can include deposition, oxidation, nitridation, etching, polishing, cleaning, lithography, metrology, etc. Other processes can be performed as well. The load lock apparatuses 107A, 107B can be adapted to interface with the factory interface 117 or other system components that can receive the substrate 110, for example, from a substrate carrier 119 (e.g., a front-opening unified pod (FOUP)) that can dock to a load port of the factory interface 117. A factory interface robot 121 (shown in dotted lines) can be used to transfer the substrate 110 between the substrate carrier 119 and each load lock apparatus 107A, 107B. Transfer of the substrate 110 can be performed in any order or direction. The factory interface robot 121, in some embodiments, can be the same as (or similar to) the transfer chamber robot 101, but can further include a mechanism that allows the factory interface robot to move laterally in either lateral direction, as indicated by arrow 123. Any other suitable robot may be used as the factory interface robot 121.

[0025] In an embodiment, as an exemplary illustration of any robot, the transfer chamber robot 101 includes at least one arm 113 (e.g., a robot arm) and at least one end effector 115 coupled to the arm 113. The end effector 115 is controllable by the transfer chamber robot 101 to pick up a substrate 110 from the load lock apparatus 107A or 107B, guide the substrate 110 through one of the slit valves 111 of the processing chambers 103, and precisely place the substrate 110 on a substrate support of the processing chamber 103.

[0026] In various embodiments, one or more of the processing chambers 103 can include a window 120, at least a portion of which is embedded in the walls and liner 124 (e.g., interior walls) of the processing chamber 103. The window 120 can be a transparent crystal, which can be made of a transparent ceramic material, or can be made of a transparent material such as sapphire, diamond, quartz, or silicon carbide. The window 120 can be characterized by a transmission coefficient, a reflection coefficient, and an absorption coefficient, which may collectively be referred to as the optical coefficient. The optical coefficient may depend on factors such as the material of the window 120, the surface characteristics of the window 120, etc. For example, a brand new window can have a given transmission coefficient (e.g., a reference transmission coefficient), but over time, the window's transmission coefficient may change as the window is exposed to various processing operations in the processing chamber. For example, the transmission coefficient may change from the reference transmission coefficient due to the effects of various physical and chemical agents, which may result in a coating layer building up on the OWPS and subsequently affecting sensor characteristics. Additionally, in some embodiments, the window 120 may be pre-coated, e.g., permanently, with a first film. The first film may be disposed on the interior surface of the window 120 and may have a composition that matches the chamber chemistry. During chamber operation, e.g., while a process operation is being performed, a second film may be deposited and then (e.g., gradually) removed over time. As such, the transmission coefficient of the second film may change as a function of time, which changes the measured light intensity transmitted from the processing chamber environment and alters the measured plasma spectrum. In such an embodiment, as described below with respect to FIG. 3A , a baseline measurement may be performed after the first film is deposited on the window 120 (e.g., during fabrication of the window 120) and before the window is coated with the second film.

[0027] In various embodiments, one or more environments of the processing chamber 103 may include a plasma. The plasma may be affected by processing operations of the processing chamber, which may result in changes in the optical properties of the plasma. The optical changes in the plasma may affect the intensity of light incident on the window 120 from the processing chamber environment. Changes in the optical properties of the window 120 as well as the processing chamber 103 environment may be observed with one or more optical sensors, such as optical sensor 125. The processing chamber 103 environment may be generated during processing operations that may be performed within the processing chamber. The processing operations may be one factor that changes the transmission coefficient of the window 120 from a reference transmission coefficient. The described systems and methods enable transmission correction for such effects.

[0028] In various embodiments, the processing system 100 can include a light source (not shown in FIG. 1 ). The light source can be used as a probe light. The intensity of the probe light can be calibrated against a known, predetermined reference value. During a detection phase, the light sensor 125 detects light originating from the processing chamber environment. During a testing phase, the light source can direct the probe light into the processing chamber 103 through the window 120. Thus, the light sensor 125 can collect both light coming from the processing chamber environment and a portion of the probe light reflected from the window. In other embodiments, the probe light can be broadband light (e.g., a spectral range of wavelengths comparable to the center wavelength, i.e., δλ≈λ). In some embodiments, the light source can be a pulsed light source configured to turn off and on at regular intervals. In some embodiments, the light source can be controlled (e.g., by a controller device) to turn off and on based on commands.

[0029] In some embodiments, light, such as probe light and / or light used for optical reflectometry measurements, may be collimated, partially reflected, and partially transmitted through window 120, as discussed in more detail with reference to FIGS. 2-4 . In some embodiments, processing system 100 may further include an optical coupling device. The optical coupling device may be coupled to one or more of optical sensor 125 or the light source. The optical coupling device may focus the reflected light into an opening of a fiber optic cable, which may be coupled to optical sensor 125. The optical coupling device may be configured to transmit the probe light from the light source to the window. The optical coupling device may further be configured to transmit light reflected from the window (during the test phase) and light transmitted through the window (during both the detection phase and the test phase) from the window to optical sensor 125.

[0030] The controller 109 (e.g., a tool and equipment controller) can control various aspects of the processing system 100, such as the gas pressures in the processing chamber 103, the individual gas flows, spatial flow ratios, the temperature of various chamber parts, and the radio frequency (RF) or electrical conditions of the processing chamber 103. The controller 109 can receive signals from and send commands to the factory interface robot 121, the transfer chamber robot 101, one or more sensors, and / or other processing components of the processing system 100. Thus, the controller 109 can control the start and stop of processing, adjust deposition rates, types or mixing ratios of deposition compositions, etc. The controller 109 can also receive and process sensory data from various sensors.

[0031] In various embodiments, processing device 130 is coupled to light sensor 125 and / or a light source (not shown in FIG. 1 ). Processing device 130 may be configured to receive and process sensory data, such as optical reflectometry measurements, including the intensities of light during the detection and testing phases obtained by light sensor 125. Processing device 130 may calculate or determine a transmission coefficient of window 120 using the difference between the intensities of light detected during the testing phase and the detection phase. Processing device 130 may then determine the intensity of light incident on window 120 from the environment using the intensities detected during the detection phase and the determined transmission coefficient of window 120.

[0032] Processing device 130 can be and / or include a computing device such as a personal computer, a server computer, a programmable logic controller (PLC), a microcontroller, etc. Processing device 130 can include (or be) one or more processing devices, which can be general-purpose processing devices such as a microprocessor, a central processing unit, etc. More specifically, the processing device can be a complex instruction set computing (CISC) microprocessor, a reduced instruction set computing (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, or a processor implementing other instruction sets or combinations of instruction sets. The processing device can 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 processor (DSP), a network processor, etc. Processing device 130 can include a data storage device (e.g., one or more disk drives and / or solid-state drives), a main memory, a static memory, a network interface, and / or other components. Processing device 130 can execute instructions to perform any one or more of the methods and / or embodiments described herein. The instructions may be stored in a computer-readable storage medium, which may include main memory, static memory, secondary storage, and / or a processing device during execution of the instructions.

[0033] FIG. 2 shows a simplified side view of a system 200 for optical reflectometry correction, according to one embodiment. The system 200 can include, for example, a processing chamber 103 having a liner 124, as shown in FIG. 1 . The processing chamber 103 can include a wall 222 to which the liner 124 is attached. The liner 124 can be specially designed to have high chemical resistance to process chemistries, minimizing physical or chemical changes to the liner to maximize its lifetime. Additionally, at least a portion of the window 120 can be embedded within the wall 222 and liner 124, as shown. The window 120 can be made of a transparent ceramic material or a durable, transparent material such as sapphire, diamond, quartz, silicon carbide, or a combination thereof.

[0034] In an embodiment, system 200 further includes a light source 201 (e.g., a broadband light source), an optical coupling device 204 (e.g., a collimator, a waveguide, an optical fiber, a mirror, or any combination thereof), an optical sensor 225, a controller 109, and a processing device 130. The light source 201 and the optical sensor 225 may be optically coupled to the optical coupling device 204 via one or more optical fiber cables 232.

[0035] In one embodiment, light source 201 is configured to be turned on and off. For example, light source 201 can be a pulsed light source that is turned on and off to selectively direct probe light into process chamber 103. In some embodiments, light source 201 can be a continuous light source. In some embodiments, light source 201 can be a flash lamp, such as a pulsed xenon source. In other embodiments, the wavelength range can be further varied, for example, and can be set near near-infrared wavelengths. Additional or different embodiments are contemplated for light source 201 with various capabilities and wavelengths. In some embodiments, light source 201 can generate broadband light.

[0036] In various embodiments, the optical coupling device 204 can be adapted to collimate or otherwise transmit light in two directions along the optical path. The first direction can include light from the light source 201 that is collimated and transmitted through the window 120 into the processing chamber 103. The second direction can be the direction of reflected light from the window 120 returning into the optical coupling device 204. The reflected light can be focused into the fiber optic cable 232 and thereby directed along the optical path to the light sensor 225 in the second direction. Additionally, the fiber optic cable 232 can be coupled between the light sensor 225 and the light source 201 for efficient transfer of light from the light source 201 to the window 120 and back to the light sensor 225. In some embodiments, the optical coupling device 204 can transmit probe light from the light source 201 to the window 120, and similarly can transmit first light and / or second light from the window 120 to the light sensor 225.

[0037] In some embodiments, the light sensor may be a spectrometer, a CCD camera, etc. The light sensor 225 may require calibration on the same schedule or on a longer schedule compared to the light source 201. The light sensor 225 may be adapted to detect the spectrum of reflected light received from the light coupling device 204, for example, light reflected back from the window 120 and focused by the light coupling device 204 into the fiber optic cable 232, as well as emissions from the chamber's environment.

[0038] In various embodiments, the controller 109 includes or is coupled to a processing device 130, and includes or is coupled to a memory 134 or other computer storage. The processing device 130 may be coupled to both the light source 201, the light sensor 225, and the processing chamber 103. The processing device 130 can instruct the light source 201 to emit a flash of light and then receive a first spectrum (e.g., the dependence of light intensity I(λ) on wavelength) from the light sensor 225. The processing device 130 can also leave the light source off and receive a second spectrum (e.g., I(λ)) from the light sensor 225 when the light source 201 is off. The second spectrum can represent the OES of the plasma or chemical process in the processing chamber. The processing device 130 can subtract the second spectrum from the first spectrum to determine an instantaneous reflectometry signal (e.g., I(λ)-I(λ)). The processing device 130 can then mathematically fit the reflectometry signals I1(λ)-I2(λ) to one or more thin film models to determine one or more optical thin film properties of the process film layer deposited on the window 120.

[0039] Processing device 130 may be further configured to determine a transmission coefficient of window 120. Processing device 130 may determine the transmission coefficient by determining the difference between a first spectrum corresponding to the intensity measured by light sensor 225 when light source 201 is on and a second spectrum corresponding to the intensity values ​​measured by light sensor 225 when light source 201 is off.

[0040] FIG. 3A is a schematic diagram of a system 300 at the beginning of a reference measurement for transmission correction of a plasma OES, according to one embodiment. Although not all components are shown, the system 300 can be the same as or similar to the system 100 of FIG. 1 and the system 200 of FIG. 2. The system 300 can include a window 320a. The window 320a can be a process chamber window for optical inspection and reflectometry measurements. The window 320a can be a process chamber window that has not yet been used in the fabrication of a substrate, wafer, or sample and therefore has not been exposed to any materials used in processing operations such as deposition, etching, polishing, etc. The window 320a can be used to obtain a reference measurement, which may be affected by coatings from the OWPS.

[0041] The window 320a may be permanently pre-coated (e.g., during manufacturing of the window 320a) with a first thin film that matches the chemical properties of the processing chamber. The reference measurements obtained include the optical coefficients of both the window 320a and the first thin film.

[0042] System 300 can include a probe light 301 and a chamber light 307. Probe light 301 can be generated by a light source outside the processing chamber. Probe light 301 can have an intensity L, which can be known, for example, via a reference calibration. Chamber light 307 can be light transmitted through window 320a from the environment of the processing chamber. Chamber light 307 can be incident on window 320a from inside the processing chamber and have an intensity I1, which can depend on the environment of the processing chamber. For example, the characteristics of plasma 331 in the processing chamber can depend on whether a processing operation is present, the nature of the processing operation (e.g., deposition, etching, polishing, etc.), etc. Chamber light 307 can travel through plasma 331 in the processing chamber. Both probe light 301 and chamber light 307 can be incident on window 320a perpendicular to the surface of window 320a.

[0043] It is worth noting that, in general, if there is no absorption (or absorption can be neglected), the sum of the reflection and transmission coefficients is 1, i.e., R+T=1. Furthermore, the transmission and reflection coefficients are independent of which side of the window the light is incident from. At least two reference measurements can be taken with sensors that can be located outside the process chamber. The first reference measurement can be taken when the probe light 301 is on. The measured intensity is

[0044]

number

number

[0045]

number

number

[0046] Then, using the determined reference transmission coefficient T1, the processing device may be able to infer the intensity I1 of the chamber light 307 incident on the window 320a from the intensity of the light transmitted through the window. More specifically,

number

[0047] FIG. 3B is a schematic diagram of a system 300 for transmission correction of a plasma OES, according to one embodiment. Several factors may require correction to obtain accurate plasma OES. In particular, plasma OES may be affected by changes in the plasma 331b in the processing chamber environment as well as surface degradation of the window 320b. As shown in FIG. 3B, the window 320b is identical to the window 320a, except that the window 320b has undergone many processing operations, and the inner surface of the window 320b has become roughened by deposition, etching, aging, etc. Changes in the inner surface of the window 320b may occur over long timescales, such as on the order of the time required to perform many processing operations. Changes in the inner surface of the window 320b may result in the presence of a surface layer 333. The surface layer 333 may be caused by long-term changes in the window 320b, which may include surface roughness, intrusions or particles, or cracks in the surface of the window 320b, as well as short-term changes in the window 320b, which may include short-term material deposition. Additionally, a second thin film may be present at window 320b over the first thin film layer as described with respect to FIG. 3A. The second thin film may have a variable thickness, e.g., the second thin film may be added, thickened, thinned, and / or removed by processing operations in the processing chamber. Because the reference measurement takes into account the optical properties of the window and the first thin film, the results of measurements such as those described below can be used to compensate for the variable thickness and optical properties of the second thin film.

[0048] During processing operations, the plasma 331b in the processing chamber environment may itself be changing. For example, the specimen may undergo various plasma-based processes. In some cases, the processing chamber may undergo a cleaning process, which may also require a plasma process. These plasma effects affect the light transmitted through the window 320b from the processing chamber environment.

[0049] Both the window effect and the plasma effect affect the light received by the sensor compared to the reference case of Figure 3 A. The described systems and methods provide a solution for distinguishing whether a change in the intensity of light received by the sensor is due to a change in the intensity of light incident on the inner surface of the window (e.g., plasma effect) or due to a change in the inner surface of the window (window effect).

[0050] As in FIG. 3A, at least two measurements can be taken by the sensor. The first measurement can be taken when the probe light 301 is on. A transmitted portion 317 of the probe light 301, having an intensity of LT2, can be transmitted through window 320b (into the process chamber), while a reflected portion 315 of the probe light 301, having an intensity of LR2, can be reflected by window 320b and returned to the sensor, where T2 and R2 are the transmission and reflection coefficients of window 320b, respectively. In addition, chamber light 319 can be generated from the environment of the process chamber and can be incident on window 320b from inside the process chamber with intensity I2. (The intensity I2 of chamber light 319 incident on window 320b in FIG. 3B can be different from the intensity I1 of chamber light 307 incident on window 320a in FIG. 3A due to the changing or different plasma 331b in the two cases.) In this case, as before, the sensor can take the first measurement. I on =L(1-T2)+I2T2 can be obtained, as well as the second measurement I off =I2T2 can be obtained.

[0051] The processing device may determine a new transmission coefficient for the window;

number

[0052] The processing device can then use the second measurement and the transmission coefficient to determine the intensity of the chamber light 319 incident on the window 320a. More specifically,

number

[0053] By comparing I2 with I1, changes in chamber light incident on window 320b from the processing chamber environment can be determined, which provides information about changes in plasma 331b. Any changes that remain unaccounted for may then be due to window effects. Once the transmission coefficient T2 characterizing the current state of the window is determined, the determined transmission coefficient can be used in conjunction with a reference transmission coefficient T1 to determine the condition of the processing chamber environment. For example, if a window (referred to herein as a reference window; the reference window may be a new window, a cleaned window, etc.) is characterized by a reference transmission coefficient T1, it can be known (e.g., from empirical testing, physical and / or chemical modeling, or any combination thereof) that a particular technological process is associated with an environment that generates a light intensity i1 detected by the light sensor. This means that the intensity of light incident on the reference window is i1 / T1. If, during the execution of the technological process, the sensor detects an intensity i2, while the pulse reflectometry measurement detects that the transmission coefficient of the current window is T2, the processing device can determine that the intensity of the light incident from the current environment of the processing chamber is i2 / T2. Therefore, the processing device can calculate an incident intensity mismatch parameter Θ ...

[0054]

number

[0055] Similarly, in one embodiment, but not in a further embodiment, measurements can be performed across a wavelength range of interest, e.g., using a broadband light source and a broadband sensor. For example, during a testing phase, processing device 130 can detect the intensity of light for each wavelength (e.g., L(1-T2)+I2T2) of a set of wavelengths (e.g., within a wavelength interval [λ1, λ2]). During a detection phase, processing device 130 can similarly detect the intensity of light (e.g., I2T2) for each wavelength of the set of wavelengths. Based on the two intensities, processing device 130 can determine the transmission coefficient of the window for each wavelength.

[0056] The intensity mismatch parameter can then be determined as a function x(λ) of the wavelength-intensity mismatch parameter. Such wavelength-resolved mismatch parameters can be used to detect the appropriate composition of the processing chamber environment. For example, a mismatch specific to a particular wavelength (e.g., corresponding to the emission wavelength of a particular chemical A) can indicate that chemical A is present at too low (too high) a concentration in the current processing chamber environment.

[0057] In some embodiments, light incident from the environment within the processing chamber may be diffuse (either inherently or due to scattering in the environment by gases, plasma, etc.), and a directional light selector such as a collimator may be used to select or direct light that is incident substantially perpendicularly on the inner surface of the window (e.g., between 0 and 10 degrees from the normal to the surface of the window). In some embodiments, the first light and the second light may be incident on the window 320a at a non-perpendicular angle.

[0058] In some embodiments, the above-mentioned measurements can be performed in the time domain. For example, the transmission coefficient T2(t) of the window is time-dependent (e.g., as some material from the processing chamber adheres to the window), which can result in a drift of the measured intensity i2(t) over time. By repeatedly determining the current transmission coefficient of the window, e.g., at regular time intervals, the processing device 130 can determine whether the conditions in the processing chamber remain suitable (e.g., remain consistent with the specifications of the processing operation being performed in the processing chamber).

[0059] FIG. 4 is a flow diagram of a method 400 for transmission correction for plasma OES using optical reflectometry measurements, according to one embodiment. In some embodiments, method 400 can be performed using processing logic. The processing logic can include hardware, software, or any combination thereof. Method 400 can be performed using the systems and components shown in FIGS. 1 and 2 , or a combination thereof. Some or all of the blocks of method 400 can, in some embodiments, be executed in response to instructions from a computing device or microcontroller. The microcontroller can include one or more processing devices, such as a central processing unit (CPU), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a digital signal processor (DSP), a network processor, etc. The processing device is communicatively coupled to one or more memory devices, such as read-only memory (ROM), flash memory, static memory, dynamic random access memory (DRAM), etc. The microcontroller can be part of a desktop computer, a laptop computer, a workstation, a wearable device (e.g., a tablet, a smartphone, etc.), a cloud-based computing service, etc. In some embodiments, the microcontroller is part of a larger network of computing devices. In some embodiments, an external computing device that communicates with the microcontroller can reconfigure the microcontroller (e.g., change settings, update memory, or otherwise reprogram it).

[0060] The method 400 may begin with processing logic detecting a first intensity (block 402). The first intensity may correspond to a first light that includes a portion of the probe light reflected from a window of the processing chamber (e.g., having intensity L = L(1-T)) and light transmitted through the window from the environment of the processing chamber (e.g., having intensity I). Thus, the intensity of the first light may be L(1-T) + I. The processing logic may detect the first intensity during a first time when the probe light is directed through the window into the processing chamber. The processing logic may detect a second intensity of the second light (block 404). The second light may include light transmitted through the window from the environment of the processing chamber (e.g., having intensity I). The processing logic may detect the second intensity during a second time when the probe light ceases to be directed through the window into the processing chamber. The processing logic may use the first intensity and the second intensity to determine a transmission coefficient of the window (block 406).

[0061] To determine the transmission coefficient of the window, processing logic can determine the difference (e.g., ΔI) between the first intensity and the second intensity (e.g., ΔI = L(1 - T)). Correspondingly, using the measured difference ΔI and the known intensity L of the probe light (e.g., from a calibration measurement), processing logic performing method 400 can determine the transmission coefficient of the window in the current state. Processing logic can further determine the intensity of light incident on the window from the environment of the processing chamber. Processing logic can determine that intensity using the second intensity and the transmission coefficient of the window. The environment of the processing chamber may include plasma or other chemical gases.

[0062] The processing logic can direct the probe light to be incident normally on the surface of the window. Further, the processing logic can perform measurements of ambient generated light that is incident normally on the surface of the window.

[0063] The processing light determines the transmission coefficient of the window and / or the intensity of light transmitted from the environment for a single frequency or over a range of frequencies, thereby obtaining values ​​as a function of frequency.

[0064] In a further embodiment, processing logic can determine the state of the processing chamber based on the transmission coefficient T of the window (block 408). For example, a large difference between the baseline transmission coefficient and the transmission coefficient at a given time can indicate that the window has been subjected to surface roughening, particle bombardment, changes in the processing chamber environment, aging, etc. Additionally, processing logic can determine the state of the processing chamber environment based on the intensity incident on the window via the processing chamber environment. The difference between the baseline intensity of light incident on the window and the intensity of the light at a given time can provide information about the processing operation. In either or both of these cases, processing logic can adjust the state of the processing chamber based on the determined difference between the baseline value and the value at a later time (block 410).

[0065] 5 illustrates a block diagram of an example processing device 500 that operates in accordance with one or more aspects of the present disclosure. The processing device 500 may be the controller 109 of FIG.

[0066] The exemplary processing device 500 may be connected to other processing devices within a local area network (LAN), an intranet, an extranet, and / or the Internet. The processing device 500 may be a personal computer (PC), a set-top box (STB), a server, a network router, switch, or bridge, or any device capable of executing (serially or otherwise) a set of instructions that specify actions to be taken by the device. Furthermore, although only a single exemplary processing device is shown, the term "processing device" shall also be interpreted to include any collection of processing devices (e.g., computers) that individually or collectively execute a set (or sets) of instructions to perform one or more of the methodologies discussed herein.

[0067] The exemplary processing device 500 may include a processor 502 (e.g., a CPU), a main memory 504 (e.g., read-only memory (ROM), flash memory, dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM), etc.), a static memory 506 (e.g., flash memory, static random access memory (SRAM), etc.), and a secondary memory (e.g., a data storage device 518), which may communicate with each other via a bus 530.

[0068] The processor 502 represents one or more general-purpose processing devices, such as a microprocessor, a central processing unit, or the like. More specifically, the processor 502 may be a complex instruction set computing (CISC) microprocessor, a reduced instruction set computing (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, a processor implementing other instruction sets, or a processor implementing a combination of instruction sets. The processor 502 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 processor (DSP), a network processor, or the like. According to one or more aspects of the present disclosure, the processor 502 may be configured to execute instructions implementing the method 400 of thickness variation mapping.

[0069] The example processing device 500 may further include a network interface device 508 that may be communicatively coupled to a network 520. The example processing device 500 may further include a video display 510 (e.g., a liquid crystal display (LCD), a touch screen, or a cathode ray tube (CRT)), an alphanumeric input device 512 (e.g., a keyboard), an input control device 514 (e.g., a cursor control device, a touch screen control device, a mouse), and a signal generation device 516 (e.g., an audio speaker).

[0070] The data storage device 518 may include a computer-readable storage medium (or, more specifically, a non-transitory computer-readable storage medium) 528 on which one or more sets of executable instructions 522 are stored. According to one or more aspects of the present disclosure, the executable instructions 522 may include executable instructions that implement the method 400 of thickness variation mapping.

[0071] The executable instructions 522 may also reside, completely or at least partially, within the main memory 504 and / or within the processor 502 during execution thereof on the exemplary processing device 500, with the main memory 504 and the processor 502 also constituting computer-readable storage media. The executable instructions 522 may further be transmitted or received over a network via the network interface device 508.

[0072] While computer-readable storage medium 528 is illustrated in FIG. 5 as a single medium, the term "computer-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 operating instructions. The term "computer-readable storage medium" should also be interpreted to include any medium that can store or encode a set of instructions for execution by a machine that cause the machine to perform one or more of the methods described herein. Accordingly, the term "computer-readable storage medium" should be interpreted to include, but is not limited to, solid-state memory, and optical and magnetic media.

[0073] It is to be understood that the foregoing description is intended to be illustrative, and not limiting. Many other embodiments will be apparent to those skilled in the art upon reading and understanding the foregoing description. While the present disclosure describes particular examples, it will be recognized that the systems and methods of the present disclosure are not limited to the examples set forth herein, but may be practiced with modification within the scope of the appended claims. Accordingly, the specification and drawings should be regarded in an illustrative, and not a restrictive, sense. The scope of the present disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

[0074] The above-described method, hardware, software, firmware, or code set embodiments may be implemented via instructions or code stored on a machine-accessible, machine-readable, computer-accessible, or computer-readable medium that is executable by a processing element. "Memory" includes any mechanism that provides (i.e., stores and / or transmits) information in a form readable by a machine, such as a computer or electronic system. For example, "memory" includes random access memory (RAM), such as static RAM (SRAM) or dynamic RAM (DRAM), ROM, magnetic or optical storage media, flash memory devices, electrical storage devices, optical storage devices, acoustic storage devices, and any type of tangible machine-readable medium suitable for storing or transmitting electronic instructions or information in a form readable by a machine (e.g., a computer).

[0075] The foregoing description has set forth numerous specific details, such as examples of particular systems, components, methods, etc., to provide a thorough understanding of some embodiments of the present disclosure. However, it will be apparent to those skilled in the art that at least some embodiments of the present disclosure may be practiced without these specific details. In other instances, well-known components or methods have not been described in detail or have been presented in a simplified block diagram format to avoid unnecessarily obscuring the present disclosure. Thus, the specific details described are merely exemplary. Particular implementations may vary from these exemplary details and still be intended to be within the scope of the present disclosure.

[0076] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in one embodiment" and "in one embodiment" or "in one embodiment" and "in one embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. In addition, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or." When the term "about" or "approximately" is used herein, it is intended to mean that the stated nominal value is accurate to within ±10%.

[0077] Although the operations of the methods herein are shown and described in a particular order, the order of the operations of each method may be changed so that certain operations can be performed in reverse order, or so that certain operations can be performed at least partially concurrently with other operations. In alternative embodiments, the instructions or sub-operations of separate operations may be in an intermittent and / or alternating manner.

[0078] It is to be understood that the foregoing description is intended to be illustrative, and not limiting. Many other embodiments will be apparent to those skilled in the art upon reading and understanding the above description. The scope of the present disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. a light source, directing a probe light into the processing chamber through the window for a first time; and ceasing to direct the probe light through the window into the processing chamber for a second time period. a light source configured to: An optical sensor, detecting a first intensity of a first light during the first time period, the first light including a portion of the probe light reflected from the window and light transmitted through the window from an environment of the processing chamber; and detecting a second intensity of second light during the second time period, the second light including the light transmitted through the window from the environment of the processing chamber. an optical sensor configured to: a processing device communicatively coupled to the light sensor, the processing device comprising: determining a transmission coefficient of the window using the first intensity and the second intensity; a processing device configured to Including, the system.

2. 2. The system of claim 1, wherein the processing device determines a difference between the first intensity and the second intensity to determine the transmission coefficient of the window.

3. 10. The system of claim 1, wherein the processing device is further configured to use the second intensity and the transmission coefficient of the window to determine an intensity of light incident on the window from the environment of the processing chamber.

4. The environment of the processing chamber is generated during a processing operation performed in the processing chamber, and the processing device is determining a change in the transmission coefficient caused by the processing operation from a reference transmission coefficient of the window; The system of claim 1 further configured to:

5. The system of claim 1 , further comprising an optical coupling device for delivering the probe light from the light source to the window.

6. The system of claim 5 , wherein the optical coupling device further transmits the first light from the window to the light sensor.

7. The system of claim 5 , wherein the environment of the processing chamber comprises a plasma.

8. The system of claim 5 , further comprising a collimator for directing the light transmitted from the environment normal to a surface of the window.

9. The system of claim 1 , wherein the probe light is incident on the window substantially normal to a surface of the window.

10. The system of claim 1 , wherein the intensity of the probe light is calibrated against a predetermined reference intensity value.

11. The system of claim 1 , wherein the probe light is broadband light.

12. 1. A processing chamber comprising: Windows, and a plasma gas in the processing chamber environment a processing chamber including: An optical sensor, detecting a first intensity of a first light, the first light including i) a portion of probe light reflected from the window, and ii) light transmitted through the window from the environment of the processing chamber; and detecting a second intensity of second light, the second light including the light transmitted through the window from the environment of the processing chamber. an optical sensor configured to: a processing device communicatively coupled to the light sensor, the processing device comprising: determining a transmission coefficient of the window using the first intensity and the second intensity; a processing device configured to Including, the system.

13. directing a probe light through the window into the processing chamber for a first time; ceasing to direct the probe light through the window into the process chamber for a second time period, wherein the first intensity of the first light is detected during the first time period and the second intensity of the second light is detected during the second time period; and The system of claim 12 , further comprising a light source configured to:

14. 13. The system of claim 12, wherein the processing device is further configured to use the second intensity and the transmission coefficient of the window to determine an intensity of light incident on the window from the environment of the processing chamber.

15. The system of claim 12 , wherein the intensity of the probe light is calibrated against a predetermined reference intensity value.

16. detecting a first intensity of a first light, the first light including i) a portion of the probe light reflected from a window of a process chamber, and ii) light transmitted through the window from an environment of the process chamber; detecting a second intensity of a second light, the second light including the light transmitted through the window from the environment of the processing chamber; determining a transmission coefficient of the window using the first intensity and the second intensity; and A method comprising:

17. directing the probe light through the window into the processing chamber for a first time; ceasing to direct the probe light through the window into the process chamber for a second time period, wherein the first intensity of the first light is detected during the first time period and the second intensity of the second light is detected during the second time period; and 17. The method of claim 16, further comprising:

18. 17. The method of claim 16, wherein determining the transmission coefficient of the window comprises determining a difference between the first intensity and the second intensity.

19. 17. The method of claim 16, further comprising using the second intensity and the transmission coefficient of the window to determine an intensity of light incident on the window from the environment of the processing chamber.

20. 17. The method of claim 16, wherein the probe light is incident on the window substantially normal to a surface of the window, and the light transmitted from the environment is directed by a collimator to be incident on the window normal to the surface of the window.

21. detecting the first intensity of the first light for each of a plurality of frequencies; detecting the second intensity of the second light for each of the plurality of frequencies; determining the transmission coefficient of the window for each of the plurality of frequencies using the first intensity and the second intensity detected for each frequency; 17. The method of claim 16, further comprising:

Images