Multi-mode configurable spectrometer

Abstract

The present invention provides a multi-mode configurable spectrometer, a method for operating the multi-mode configurable spectrometer, and an optical monitoring system. In one embodiment, the multi-mode configurable spectrometer includes: (1) an optical sensor configured to receive an optical input and convert the optical input into an electrical signal, wherein the optical sensor includes a plurality of active pixel regions for converting the optical input into the electrical signal; and (2) a conversion circuit having a plurality of selectable conversion circuits, the conversion circuit being configured to receive the electrical signal and convert the electrical signal into a digital output according to a selected one of the selectable conversion circuits.

Description

[0001] Information about divisional applications

[0002] This application is a divisional application of the Chinese invention patent application with application number 201810298098.1, application date March 30, 2018, and invention name “Multi-mode Configurable Spectrometer”.

[0003] CROSS REFERENCE TO RELATED APPLICATIONS

[0004] This application claims the benefit of U.S. Provisional Application Serial No. 62 / 479,576, filed by Corless et al. on March 31, 2017, entitled “Multimode Configurable Spectrometer,” and U.S. Provisional Application Serial No. 62 / 530,388, filed by Corless et al. on July 10, 2017, entitled “Multimode Configurable Spectrometer,” both of which are jointly assigned to this application and are incorporated herein by reference in their entirety. Technical Field

[0005] The present invention generally relates to optical spectroscopy systems and methods of use. One particular embodiment relates to a system and method for improved configurability and utility of a multi-mode configurable spectrometer used during semiconductor processing. Background Art

[0006] Optical monitoring of semiconductor processes is a well-established method for controlling processes such as etching, deposition, chemical mechanical polishing, and implantation. Optical emission spectroscopy ("OES") and interferometry endpoint ("IEP") are two basic types of data collection operations. In OES applications, light emitted from a process (usually emitted from a plasma) is collected and analyzed to identify and track changes in atomic and molecular species that indicate the state or progress of the monitored process. In IEP applications, light is typically supplied from an external source such as a flash lamp and directed onto a workpiece. Once reflected from the workpiece, the sourced light carries information in the form of the reflectivity of the workpiece, which indicates the state of the workpiece. Extraction and modeling of the reflectivity of the workpiece permits understanding of film thickness and feature size / depth / width (among other properties).

[0007] The continuous progress of semiconductor processes towards faster processes, smaller feature sizes and more complex structures has placed high demands on process monitoring technology. For example, higher data sampling rates (e.g., optical signal measurements or spectra per second) are required to accurately monitor much faster etching rates for very thin layers, where changes of a few angstroms (a few atomic layers) are critical, such as for fin field effect transistors (FINFETs) and three-dimensional (3D) NAND structures. For both OES and IEP methods, wider optical widths and larger signal-to-noise ratios are required in many cases to help detect small changes in reflectivity and optical emission. The cost and package size for monitoring systems are also under constant pressure as semiconductor process equipment becomes more complex, more deeply integrated and more expensive in itself. All of these requirements strive to promote the performance of optical monitoring systems for semiconductor processes. The capabilities and adaptability of suitable spectrometers are key factors in optical monitoring systems.

[0008] For many years, the semiconductor industry has been adapting and applying advanced technologies in spectroscopic instruments and systems. For example, see U.S. Patent 9,386,241 "Apparatus and Method for Enhancing Dynamic Range of Charge Coupled Device-based Spectrograph", which is incorporated herein by reference. In a spectrometer, the image sensor is a key element for determining the data sampling rate, optical bandwidth, optical signal detection sensitivity, optical signal-to-noise performance, etc. Area charge coupled devices ("CCDs") are the most common, but have multiple performance limitations and constraints (among other aspects), highly desired operating modes, and fast data rates. As described in U.S. Patent 9,386,241, complex timing, data shifting, and reading can be performed to offset certain performance issues, but effects such as multiple signal mixing, cross contamination, and slower data sampling rates remain due to the physical structure of existing devices and the required pixel shifting scheme. Summary of the invention

[0009] In one aspect, the present invention provides a multi-mode configurable spectrometer. In one embodiment, the multi-mode configurable spectrometer includes: (1) an optical sensor configured to receive an optical input and convert the optical input into an electrical signal, wherein the optical sensor includes a plurality of active pixel regions for converting the optical input into the electrical signal; and (2) a conversion circuit having a plurality of selectable conversion circuits, the conversion circuit being configured to receive the electrical signal and convert the electrical signal into a digital output according to a selected one of the selectable conversion circuits.

[0010] In another aspect, the present invention provides a method for operating a multi-mode configurable spectrometer. In one embodiment, the method includes: (1) using at least one of a plurality of active pixel regions of an optical sensor to convert an optical input into an electrical signal; (2) providing the electrical signal to a conversion circuit having a plurality of selectable conversion circuits; and (3) converting the electrical signal into a digital output via one of the selectable conversion circuits.

[0011] In another aspect, the present invention provides an optical monitoring system. In one embodiment, the optical monitoring system includes: (1) an optical interface configured to transmit light observed from a processing chamber; (2) a multi-mode configurable spectrometer configured to receive the light as an optical input from the optical interface. The multi-mode configurable spectrometer includes: (2A) an optical sensor configured to convert the optical input into an electrical signal, wherein the optical sensor includes a plurality of active pixel regions for converting the optical input into the electrical signal; (2B) a conversion circuit having a plurality of selectable conversion circuits, the conversion circuit being configured to receive the electrical signal and convert the electrical signal into a digital output according to a selected one of the selectable conversion circuits; and (2C) a sensor controller configured to set an operating mode of the optical sensor based on the optical input and select one of the selectable conversion circuits to provide the digital output.

[0012] The present invention also provides another embodiment of a multi-mode configurable spectrometer, the multi-mode configurable spectrometer comprising: (1) an optical sensor comprising a plurality of active pixel regions for converting optical input into electrical signals and a shift register for each of the plurality of active pixel regions, wherein each of the active pixel regions is independently controllable; (2) a conversion circuit comprising a selectable conversion circuit, the conversion circuit being configured to receive the electrical signal and convert the electrical signal into a digital output according to a selected one of the selectable conversion circuits, wherein a unique set of at least four different selectable conversion circuits is connected to each of the shift registers, and the at least four different selectable conversion circuits include a circuit having a high-speed analog-to-digital converter, a circuit having a low-speed analog-to-digital converter, and a combination circuit; and (3) a sensor controller, which is configured to change the operating mode of the optical sensor and the selected one of the selectable conversion circuits to provide the digital output based on the type of the optical input. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The characteristic features of the invention which are believed to be novel are set forth in the appended claims. However, the invention itself, as well as its mode of use, additional objects and advantages, will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings, in which:

[0014] Figure 1 is a block diagram of a system including a multi-mode configurable spectrometer for monitoring and / or controlling the state of a process within a semiconductor process tool using an OES and / or an IEP in accordance with the principles of the present invention;

[0015] Figure 2 is a block diagram of a multi-mode configurable spectrometer and specific related systems constructed according to the principles of the present invention;

[0016] Figure 3 is a schematic diagram generally depicting the functional elements of a novel optical sensor and associated electronics for use in conjunction with a multi-mode configurable spectrometer in accordance with the principles of the present invention;

[0017] Figure 4 It is implemented according to the principle of the present invention from including, for example Figure 3 Flow chart of a method for reading optical data by a multi-mode configurable spectrometer of a novel optical sensor presented in;

[0018] Figure 5 It is implemented according to the principle of the present invention from including, for example Figure 3 A second flow chart of a method for reading optical data by a multi-mode configurable spectrometer of a novel optical sensor shown in;

[0019] Fig. 6A is a plot of a representative IEP optical signal (spectrum);

[0020] Figure 6B is a plot of multiple representative OES optical signals (spectra);

[0021] Fig. 7A is a plot of a representative IEP optical signal combined with a first OES optical signal;

[0022] Figure 7B is a plot of a representative IEP optical signal combined with a second OES optical signal; and

[0023] Figure 7C is a plot of a first representative OES optical signal combined with a second OES optical signal. DETAILED DESCRIPTION

[0024] In the following description, reference is made to the accompanying drawings that form a part of the present invention and are shown by way of illustration, and the features of the present invention may be practiced in specific embodiments thereof. These embodiments are described in sufficient detail to enable those skilled in the art to practice the features of the present invention, and it should be understood that other embodiments may be utilized. It should also be understood that structural, program and system changes may be made without departing from the spirit and scope of the present invention. Therefore, the following description should not be understood in a limiting sense. For the purpose of clear description, similar features shown in the accompanying drawings are indicated by similar element symbols, and similar features shown in the alternative embodiments in the drawings are indicated by similar element symbols. Other features of the present invention will be apparent from the accompanying drawings and the following detailed description. It should be noted that for the purpose of clear description, some elements in the drawings may not be drawn to scale.

[0025] Regarding monitoring and evaluating the status of semiconductor processes within process tools, Figure 1 Block diagram illustrating a process system 100 that utilizes an OES and / or IEP to monitor and / or control the state of a plasma or non-plasma process within a process tool. A semiconductor process tool 105 typically encloses a wafer 110 and (possibly) a process plasma 115 in a volume that is typically a partial vacuum and may contain various process gases. The process tool 105 may include one or more optical interfaces 120, 121, and 122 that permit observation of the chamber at various locations and in various orientations. The optical interfaces 120, 121, and 122 may include a variety of types of optical elements such as, but not limited to, optical filters, lenses, windows, apertures, fiber optic devices, etc.

[0026] For IEP applications, the light source 130 may be connected directly to the optical interface 120 or connected to the optical interface 120 via a fiber optic cable assembly 133. As shown in this configuration, the optical interface 120 is oriented perpendicular to the surface of the wafer 110 and is generally centered relative to the surface of the wafer 110. Light from the light source 130 may enter the interior volume of the process tool 105 in the form of a collimated beam 135. Once the collimated beam 135 is reflected from the wafer, it may be received again by the optical interface 120. In common applications, the optical interface 120 may be an optical collimator, or alternatively may be a focusing system and then the collimated beam 135 is focused rather than collimated. After being received by the optical interface 120, the light may be transmitted to the multi-mode configurable spectrometer 140 via a fiber optic cable assembly 137 for detection and conversion by an optical sensor 142. The light source 130 may be, for example, a flash lamp that produces light in a wavelength range from DUV to NIR, and the wavelength of interest may be selected from any wavelength region therein. For larger substrates or where understanding wafer non-uniformity is an issue, an additional normal orientation interface (not shown) may be used.

[0027] For OES applications, optical interface 122 may be oriented to collect light emissions from plasma 115. Optical interface 122 may be simply a viewport or may additionally include other optical elements, such as lenses, mirrors, and optical wavelength filters. Fiber optic cable assembly 139 may direct any light collected to multi-mode configurable spectrometer 140 and optical sensor 142 therein. Multiple interfaces may be used alone or in parallel to collect OES related optical signals. For example, optical interface 121 may be positioned to collect emissions from near the surface of wafer 110, while optical interface 122 may be positioned to observe a volume of the plasma, such as Figure 1 Other optical interfaces (not shown) may be positioned upstream / downstream of the plasma / wafer interface. Multiple interfaces may be coupled to individual fiber optic cable assemblies and direct multiple optical signals as combined optical inputs to the multi-mode configurable spectrometer 140 and optical sensor 142. Optical interfaces may also be from Figure 1 The optical interface shown in FIG. 1 is simplified and substantially removed by mounting the multi-mode configurable spectrometer 140 directly to the process tool 105 .

[0028] In many semiconductor processing applications, it is common practice to collect both OES and IEP optical signals and provide them to a spectrometer. In general, it is disadvantageous to support multiple spectrometers for each signal type due to the cost, complexity, and inconvenience of signal timing synchronization, calibration, and packaging, among other factors. However, for a single spectrometer, receiving and processing both of these optical signal types can provide a variety of problems. Typically, OES signals are continuous in time, while IEP signals can be continuous or discrete in time. The mixing of these signals leads to several difficulties because process control often requires detection of small changes in both OES and IEP signals, and inherent changes in either signal can obscure the observation of changes in the other. The following text combines Figures 6A to 7C Another discussion discusses the difficulties of optical signal detection and their alleviation by the present invention.

[0029] Advantageously, the OES and IEP optical signals transmitted via the fiber optic cable assemblies 137 and 139 can be received by the optical sensor 142 as optical inputs at the multi-mode configurable spectrometer 140, respectively. In general, the optical input may include one or more optical signals, such as the aforementioned OES and IEP signals and other continuous or discontinuous optical signals. In addition, it should be noted that any of the optical signals may be independent of or combined with other optical signals. The optical sensor 142 includes a plurality of active pixel areas for converting the optical input into electrical signals. Therefore, each active pixel area can receive one or more optical signals. It should be understood that the electrical signal within the optical sensor 142 may be any of a charge signal, a current signal, and / or a voltage signal, depending on the precise configuration of the optical sensor 142. Typically, the optical input is first converted into a charge, then the charge is converted into a voltage, and then made available to a device external to the optical sensor 142 via an output amplifier.

[0030] The multi-mode configurable spectrometer 140 may also include a conversion circuit 144 having a plurality of selectable conversion circuits, which is configured to receive the electrical signal 146 and convert the electrical signal 146 into a digital output 148 according to a selected one or more of the selectable conversion circuits. The multi-mode configurable spectrometer 140 may further include a sensor controller 150, which may be configured to direct the operation of the optical sensor 142 and select at least one of the selectable conversion circuits of the conversion circuit 144 to provide the digital output 148. The digital output 148 may be routed to the sensor controller 150 for further processing, storage, etc., and / or may also be directly / indirectly transmitted to an external system 160 for further use.

[0031] The external system 160 may be, for example, an industrial PC, PLC, or other system that employs one or more algorithms to generate an output 170, such as, for example, an analog or digital control value representing the intensity of a specific wavelength, the ratio of two wavelength bands, or a film thickness value. The external system 160 may alternatively be integrated with the multi-mode configurable spectrometer 140 to provide a more compact overall system. The OES algorithm analyzes the emission intensity signal at a predetermined wavelength and determines a control value that is associated with the state of the process and can be used to access that state, such as endpoint detection, etch depth, etc. For IEP applications, the algorithm can analyze the entire spectrum to determine the film thickness control value. For example, see U.S. Patent 7,049,156, "System and Method for In-situ Monitor and Control of Film Thickness and Trench Depth," which is incorporated herein by reference. The output 170 may be transmitted to the process tool 105 via a digital or analog communication link (e.g., Ethernet) used to monitor and / or modify the production process occurring within the process tool 105. Although Figure 1 A single process chamber of a single process tool 105 is specifically depicted, but it should be understood that the multi-mode configurable spectrometer 140 may be advantageously used in conjunction with multiple process chambers of a single process tool 105 or one or more process chambers of different process tools.

[0032] Figure 2 A block diagram illustrating an embodiment of a system 200 including a multi-mode configurable spectrometer 210 in accordance with the principles of the present invention. The multi-mode configurable spectrometer 210 may incorporate the disclosed Figure 3 The optical sensor described in one embodiment of the invention is advantageous for measuring optical signals from semiconductor processes. The multi-mode configurable spectrometer 210 can be configured to measure optical signals from an external optical device 230 (e.g. Figure 1 The optical fiber cable assembly 137 and 139 of FIG. 1 receives one or more optical signals and can send a digital output after integration and conversion of the optical signals to an external system 220. The external system 220 can also be used to control the multi-mode configurable spectrometer 210, as defined herein, by, for example, selecting an operating mode or controlling details of an operating mode (e.g., integration timing).

[0033] The multi-mode configurable spectrometer 210 may include an optical interface 240, such as an SMA or FC fiber optic connector or other optomechanical interface. Additionally, optical components 245 (such as slits, lenses, filters, and gratings) may be used to shape, direct, and chromatographically separate the received optical signals and direct them to an optical sensor 250 for integration and conversion. The low-level functions of the optical sensor 250 may be provided by commonly available optical components. Figure 1The sensor controller 150 of the optical sensor 250 is associated with or is controlled by elements (such as a programmable integrated circuit 260 and a processor 270) as part of it. The programmable integrated circuit 260 may be a field programmable gate array (FPGA) and will be referred to as FPGA 260 in the present invention and the figures hereinafter. FPGA 260 can generate converter control signals for the A / D conversion circuit 280 and generate optical sensor timing signals for the optical sensor 250. Processor 270 can also generate converter control signals and optical sensor timing signals. Processor 270 can be various types of processors, including computer processors with a reduced instruction set computing architecture. Other examples of processors that can be used include Intel processors and digital signal processors (DSPs) (such as from BlackFin). After optical to electrical conversion is performed within the optical sensor 250, the signal can be directed to the A / D conversion circuit 280 and converted from electrical to digital signals. The A / D conversion circuit 280 can be included as Figure 1 One of the several conversion circuits in the conversion circuit 144 and the following combined Figure 3 The conversion circuit is discussed in more detail.

[0034] The digital signal from the A / D conversion circuit 280 may then be stored in the memory 290 for immediate or later use and transmitted to the external system 220 (eg, Figure 1 The multi-mode configurable spectrometer 210 further includes a power supply 295 that provides the voltage necessary for the components within the multi-mode configurable spectrometer 210 to operate. The connections between the components of the system 200 and the multi-mode configurable spectrometer 210 may be conventional connections. Although certain interfaces and relationships are indicated by arrows, the multi-mode configurable spectrometer 210 may include additional interactions and control relationships. The digital signal may include one or more values ​​representing one or more optical signals included in the optical input to the optical sensor 250. In general, for a spectrometer, the digital signal typically includes a digital representation of a spectrum. For example, a spectrum may include 1024 elements, each of which has a certain digital type, such as an unsigned 16-bit integer.

[0035] To address the limitations of prior art spectrometers and integrated imaging optical sensors, new configurations of optical sensors are required. Figure 3 is a schematic diagram in accordance with the principles of the present invention, which generally depicts the functional elements of an embodiment of a novel optical sensor 300 and associated conversion circuitry 399 useful for spectroscopy and semiconductor process control. The optical sensor 300 generally includes multiple active pixel areas that can be controlled either dependently or independently. Figure 3 , only two regions are shown and discussed for clarity, but a greater number of regions may be used to advantage as described herein.

[0036] Herein, the terms "horizontal" and "vertical" rows are used to describe the internal geometry of the optical sensor 300. It should be understood that this is a conversion problem, where the "longer" or higher element count axis of the optical sensor is usually labeled as the "horizontal" direction. In spectroscopy applications, it is common to directional alignment of the long / horizontal axis of the optical sensor with the wavelength dispersion. The active pixel areas 310 and 311 of the optical sensor 300 can each include several (e.g., ~3000) tall pixels (~2000 microns) in a single horizontal row. This configuration is different from typical prior art optical sensors in which many rows of shorter pixels (e.g., 128 rows of pixels with a height of 24 microns) are utilized. High pixels of approximately 1000 to 4000 microns are suitable for use in imaging spectrometer systems and are well matched to near-unity slit heights and imaging system magnifications. Pixels of a limited number of rows (e.g., 2 to 10 rows) may be used alternatively, but may further require additional vertical timing operations, which may slow down the operation of the optical sensor 300. The additional rows add the ability to spatially subdivide each active pixel area, and can provide support for additional multiplexing of optical signals (two or more optical signals per active pixel area) and control (the ability to read all or any portion of the rows of pixels of each active pixel area) onto each active pixel region.

[0037] Although not required, an additional pixel region or physical gap 315 may be advantageously positioned between the active pixel regions 310 and 311 of the optical sensor 300 to provide optical and electrical isolation between the regions 310 and 311. The width of the physical gap 315 may be approximately 10's to 100 microns to ensure optical isolation of the regions 310 and 311. The active pixel regions 310 and 311 may also include optically opaque regions 312 and 313, which may be used for dark current / signal and DC offset compensation, respectively. Because such regions may be made optically opaque by a thick silicon layer that is transmissive to NIR wavelengths, regions 312 and 313 are most effectively placed near the ends of the optical sensor 300 where UV wavelengths are desired to be illuminated. Regions 312 and 313 may include, for example, two to four or more pixels that support determination of an average electrical offset level. In Figure 3 , areas 312 and 313 are shown at the ends of the active pixel area opposite the connections to the conversion circuitry. The location of these opaque areas and the orientation of the connections to the conversion circuitry can be changed as desired, such as the pin-out design of the actual semiconductor design of the optical sensor 300.

[0038] In the case where regions 310 and 311 each include a single row of pixels, a single vertical shift transfers the integrated electrical signal from active pixel regions 310 and 311 to their respective horizontal shift registers 320 and 321 as indicated by arrows 330 and 331. The shift of one region "upward" and another region "downward" is a simplification of the diagram and (possibly) actual semiconductor architecture. In order to provide the ability to shift all regions in one direction, signal routing will be more complex. In the case of three regions, the signal from the center region will have to be routed under or around the two other regions. In addition, if each / any region 310 and 311 has more than one row of pixels, multiple shifts are required. In addition, the vertical shifts of each of the multiple active pixel regions or their individual rows can be synchronized, interleaved or simultaneous. Compared to existing CCDs, the optical sensor configuration results in faster and simpler timing, and there is no need to shift charge between overlapping integrated regions, thereby avoiding a major source of optical signal contamination. In one example, the combination of the active pixel area and the horizontal shift register of the optical sensor 300 supports a full well capacity of 300 to 400 thousand electrons, a signal linearity of 5% or less, and a signal dynamic range of greater than 14,000.

[0039] After vertical shifting, the electrical signals in the horizontal shift registers 320 and 321 may be horizontally shifted (as indicated by arrows 340 and 341, respectively) to respective high speed A / D converters 350 and 351 and / or respective low speed A / D converters 352 and 353 located on associated conversion circuitry 399. The inclusion of low speed and high speed A / D converters and the ability to select between low speed and high speed A / D converters permits the selection of fast readout speed (high speed A / D) or low noise (low speed A / D). A variety of clock speeds and pixel sampling techniques may be used for each of the high speed and low speed A / D converters. Furthermore, the clock speed may be dynamically changed to optimize the conversion of the electrical signals from the optical sensor 300 for a particular operating mode. In general, the combination of the optical sensor 300 and the conversion circuitry 399 provides an operating mode that supports a balance between data rate (e.g., spectra / second), additional digital resolution, and signal-to-noise performance. Specifically, the conversion circuit 399 can be configured to multi-sample or oversample the electrical signal waveform in the regions generally defined as "DC / reference level" and "signal level" from the shift register to produce a differential digital signal depending on the A / D converter clock speed, the desired signal-to-noise performance, and the data sampling rate (per spectrum).

[0040] In conjunction with high speed A / D converters 350 and 351 and / or corresponding low speed A / D converters 352 and 353, optical sensor 300 may include dual outputs for each horizontal shift register. Specifically, output 324 may be a low speed and low noise output associated with horizontal shift register 320 and connected to converter 352; and output 325 may be a low speed and low noise output associated with shift register 321 and connected to converter 353. In addition, output 326 may be a high speed output associated with horizontal shift register 320 and connected to converter 350; and output 327 may be a high speed and high noise output associated with shift register 321 and connected to converter 351. Although combinatorial circuit 370 is shown connected to outputs 326 and 327, outputs 324 and 325 may be substituted. Horizontal shift registers 320 and 321 and associated elements of conversion circuit 399 may be clocked synchronously or asynchronously, and each converter may operate at an independently selectable clock speed. Synchronous clocking provides simultaneous parallel signals from each active pixel region, while asynchronous clocking can be used to support interleaving of signals from active pixel regions. The optical sensor 300 and conversion circuit 399 can use a suitable 18-bit A / D converter to achieve high speed operation of one millisecond per spectrum per active pixel region and produce a digital signal with a high dynamic range (e.g., 100 dB). To support such high data sampling rates (e.g., spectrum / second), Figure 2 FPGA 260 and processor 270 may provide data compression and other high-speed signal processing; this may be performed before the data is transmitted for further processing by, for example, external system 220. Typically, high-speed operation allows very strong optical signals to be measured, and low-noise (slow) operation allows very weak optical signals to be measured, and thus the combination enhances the overall system dynamic range.

[0041] After conversion, the digital signal is available at ports 360, 361, 362 and 363 and is transmitted to Figure 2 290, processor 270, and FPGA 260. Alternatively, the signal from the horizontal shift register may be directed to a combinational function, such as combinational circuit 370, and then converted by A / D converter 375 and made available at port 380. A / D converter 375 may be of a low speed or high speed type, or conversion circuit 399 may include a selectable low speed / high speed A / D converter for the signal caused by combinational circuit 370. Combinatorial circuit 370 may include an addition circuit, a difference circuit, a division circuit, a multiplication circuit, or an interleaving circuit, and may be a single element configured to perform the function of one of these combinational circuits.

[0042] Any signal path from the horizontal shift registers 320 and 321 to the respective A / D converters may be selected as desired by the generated converter control signals and optical sensor timing signals provided by, for example, the FPGA 260 or the processor 270. Selection via the converter control signals may be by, for example, electrically enabling or disabling a circuit or opening / closing a switch. The configurability of the optical sensor 300 and conversion circuit 399 permits multi-mode adaptable use of the sensor, such as signal summing or averaging for increased dynamic range, signal differentiation for common mode correction and variation detection, and parallel independent signals. Although Figure 3 399, but any of the various A / D converters depicted and the combining circuit 370 may be integrated with the optical sensor 300. For example, the combining circuit 370 may be executed in the analog domain within the optical sensor 300 or within the conversion circuit 399. Optimal signal performance may be expected by combining on the optical sensor 300. Furthermore, the combining circuit 370 may be executed, for example, Figure 1 The digital domain within the sensor controller 150 is then subject to A / D quantization and digital math errors. Figure 3 In FIG. 1 , all converters and outputs are shown as connected at a single end of the optical sensor horizontal shift registers 320 and 321, but it should be understood that the converters and outputs can be conveniently placed at either end / both ends of the shift registers. In certain layouts, having different outputs at each end of the horizontal shift registers 320 and 321 can provide the benefit that no switching components are required inside the optical sensor, and the electrical signal output can be directed simply by changing the phase of the timing signal to the optical sensor 300. The conversion circuit 399 can be similar to Figure 1 The conversion circuit 144 is composed of a subsystem of a multi-mode configurable spectrometer (e.g. Figure 1 The sensor controller 150 may generate the converter control signal and the optical sensor timing signal based on the selected operating mode, which may be received from the external system 220, for example. For example, the FPGA 260 or the processor 270 may be programmed to generate the converter control signal and the optical sensor timing signal to enable and disable different operating modes and configurations of the optical sensor 300 and the conversion circuit 399.

[0043] The active pixel areas 310 and 311 of the optical sensor 300 may further include the integration of a high-speed (in milliseconds) electronic shutter function. The electronic shutter function 390 is Figure 3denoted by a dotted line “X” displayed above the active pixel area 310 in the optical sensor 300. The electronic shutter function 390 can exhibit / permit charge integration due to sensor exposure in any whole or partial active pixel area of ​​the optical sensor 300. For example, shutter control can be independently varied along the horizontal axis of the optical sensor 300. Spatial and temporal control of the electronic shutter function 390 as part of the operating mode of the optical sensor 300 and an associated spectrometer (e.g., a multi-mode configurable spectrometer 140) can, for example, support enhanced dynamic range, gain flatness, high speed synchronization of optical signals collected from external controls, mobile or transient systems for pulsed plasmas, and the ability to support monitoring of high frequency modulated or rapidly changing source emissions without frequency overlap. The electronic shutter function 390 can be controlled, for example, via a controller, such as Figure 1 The sensor controller 150 of the multi-mode configurable spectrometer 140 .

[0044] Figure 4 is from a containing e.g. Figure 3 Flowchart of an example of a process 400 for reading optical data from a multi-mode configurable spectrometer including optical sensors and conversion circuits shown in . In this article, the optical data may be associated with any of a plurality of states of the optical input to the spectrometer (including optical signals and converted electrical / digital signals). Process 400 begins with a preparation step 410, in which the operating mode, semiconductor process type, integration time and other initial parameters may be predetermined. Next, in step 420, a selection of a predetermined operating mode for the spectrometer, the optical sensors and conversion circuits included may be made. The operating mode may include, for example, conversion circuit selection, settings and parameters for combination function selection, active area optical signal integration time, digitization scheme for maximizing dynamic range, and shutter function timing. The operating mode may be defined in an external system (e.g., Figure 1 160 ) is communicated to a multi-mode configurable controller (e.g. Figure 1 The sensor controller 150 of the multi-mode configurable spectrometer 140 is then specifically controlled by the controller (e.g., by Figure 2 FPGA 260 and processor 270 control). The operating modes can be defined with respect to the conditions and requirements of a specific semiconductor process and data requirements, as discussed below in conjunction with Table 1. For example, the operating modes can include settings and parameters based on optical connection type, optical signal type (OES / IEP), level (bright / dark), and time variation (continuous / pulsed). The operating modes can also be based on processing system optimization, such as for supporting optical data from separate sources, resulting in independent and asynchronous digital signals for each source.

[0045] Next, in step 430, data may be read from the optical sensor, the conversion circuit, and the multi-mode configurable spectrometer, such as in combination with Figures 1 to 3As discussed, as defined by the operating mode. Steps 420 and 430 may be repeated multiple times (1 ... N) to provide optical data with characteristics useful for process applications. For example, a certain operating mode may direct the reading of optical data to provide a digital output of two digital signals of OES data, wherein the first digital signal may be collected from the active pixel area 310 and the second digital signal may be collected from the active pixel area 311. Additional parameters of the operating mode may include selecting the combination circuit 370 as an addition circuit and selecting a low-speed A / D converter for improved signal-to-noise performance. In a slightly modified operating mode, where the optical input to the active pixel area 310 is much larger than the optical input to the active pixel area 311, a shutter function or other timing control may be applied to the active pixel area 310 within a portion of the integration period to reduce the amount of accumulated electrical signals. Step 430 may be performed multiple times before the process 400 returns to step 420. In addition, the selection of the operating mode during step 420 may be dynamically adapted in real time during the semiconductor process, which generates the optical input based on certain parameters of the digital signal or based on externally supplied commands. For example, if the digital signal indicates that the optical sensor is saturated, the operating mode can be adjusted to reduce the integration time of the optical signal received by the associated active pixel area. The reduction can be performed by directly changing the integration time of the active pixel area or adjusting the time of the associated shutter function. The operating mode adjustment can be performed by, for example Figure 2 The processor 270 or Figure 1 The external system 160 of FIG. 1 may be directed to the operation mode. Furthermore, the dynamic adjustment of the operation mode may require at least one cycle of steps 420 to 470 of process 400 before the adjustment occurs.

[0046] Next, in step 440, the collected optical data may be processed according to the operating mode of the multi-mode configurable spectrometer and the optical sensor. For example, if the multi-mode configurable spectrometer is used in an operating mode in which a flashlight with alternating illumination is used, then the processing may include determining the difference between when the optical data illumination is on and when it is off. The processing may be performed by, for example Figure 3 Combinatorial circuit 370, Figure 2 The processor 270 or Figure 1 The optical data may then be processed in step 450 for reduction and extraction of control value outputs which may be delivered to the process tool in step 460. The control value outputs may be determined by, for example, Figure 2 The processor 270 or Figure 1 The external system 160 is executed. In step 450, the process tool (e.g. Figure 1Output received by the process tool 105 of ...

[0047] Figure 5 According to one embodiment of the present invention, from comprising, for example Figure 3 4. The process 500 adds additional details to the process 400 regarding the internal operation of the multi-mode configurable spectrometer, optical sensor, and conversion circuitry. The process 500 begins with a preparation step 510, in which actions such as controlling FPGA functions may be defined or set, or initialization checks of the multi-mode configurable spectrometer may be performed. In step 520, a selection of a combination mode of multiple outputs of the optical sensor may be selected. In step 530, the state and timing of the shutter for the optical sensor may be selected. The shutter function may be applied, for example, individually to any of the active pixel regions to control exposure between different brightness sources while allowing consistent use of the overall spectrum (digital signal) / data rate from each active pixel region. After the shutter state selection, in step 540, the optical signal may be integrated over a predetermined amount of time. The integration time for each active pixel region of the optical sensor may be the same or different. Furthermore, in some operating modes, the integration time and signal processing of each active pixel area can be asynchronous to support interleaved or completely independent optical data collection as required when a multi-mode configurable spectrometer and optical sensor is used in conjunction with multiple independent process tools or processing chambers.

[0048] Next, in step 550, the integrated charge may be vertically shifted to an adjacent independent horizontal shift register. Next, in step 560, the electrical signal in the horizontal shift register may be horizontally shifted and converted according to the data sampling rate of the pre-selected combination mode and operating mode. In step 570, the electrical signal may be converted to a digital signal that defines the collected spectrum according to the selected conversion circuit and the converter sampling rate and oversampling in the conversion circuit. Process 500 ends with step 580, where the optical data may be stored or applied, for example, as combined with process 400 and / or Figure 1 described.

[0049] Table 1 highlights the signal type based benefits of certain operating modes of the optical sensor, conversion circuit, and multi-mode configurable spectrometer according to the principles of the present invention. The operating modes of the multi-mode configurable spectrometer can be closely associated with the semiconductor signal types to be monitored. Specifically, these signal types mentioned previously are OES and IEP signals. Figures 6A to 7C Examples are shown and described. Consider an optical sensor with two active pixel areas, e.g. Figure 3 300, and additionally considering modes of operation for independent parallel reading and summing / differential reading of optical data from active pixel areas; specific benefits over existing spectrometer systems can be observed.

[0050] Turning now to representative plots of OES and IEP optical data, Fig. 6A 6 is a plot 600 of a typical IEP optical signal (spectrum) 620 from a xenon flash lamp reflected from a wafer. Although as discussed herein, the IEP signal is considered to be a pulsed or discrete optical signal, such as produced by a flash lamp, it should be understood that the IEP signal can be time continuous or discrete. The pulsed optical signal can vary between two or more levels of light level with a defined pulse rate and duty cycle (e.g., 10 times per second at a 50% duty cycle). The focus herein is to provide a contrast with a typical time continuous OES optical signal that maintains a substantially constant optical signal level over the time period of interest. However, the pulsed optical signal produced from a flash lamp typically has a very short duty cycle or duration (typically a few microseconds) and typically has a 100% modulation depth; the pulsed optical signal produced from a pulsed plasma is more variable and the optical signal typically does not have a 100% modulation depth. The flash lamp signal of an IEP is also typically broadband in wavelength and can vary considerably over the wavelength range. Figure 6B 6 is a plot 610 of a number of typical OES optical signals (spectra) 630 and 640. OES optical signal 630 shows characteristics of both typical molecular (broadband structure near 400 nm) and atomic (narrow peak throughout) emission. OES optical signal 640 shows characteristics more exclusively of atomic emission, and the signal level is observed to vary from near zero counts to nearly 70,000 as a function of wavelength.

[0051] The amplitude of an IEP or OES spectrum collected in multiple regions of a single active pixel area of ​​an optical sensor within a spectrometer can vary greatly, and can be the result of being from different chambers or different locations in the same chamber. For many current semiconductor processing applications, small signal (or small signal change) detection is critical, and important optical signal features may be hidden when reading existing spectrometers because of contamination, crosstalk, limited dynamic range, and other issues with current optical sensor and spectrometer technology.

[0052] As mentioned in the previously cited U.S. Patent No. 9,386,241, there are multiple problems with the use of these existing optical sensors and spectrometers. The main problem is that the active pixel area is used as a circular buffer, and the signal integrated in each part of the active pixel area usually has to pass through other parts that may remain exposed and become contaminated during the shift. The resulting optical signal is a combination of signals incident on different parts in various proportions based on the shift rate, etc. In addition, because the row is shifted from one part to another, the original part of the sensor can continue to be exposed, and the integration of undesired signals can be sought. Again as mentioned in the previously cited U.S. Patent No. 9,386,241, at the cost of adding more complexity and providing lower data rates and additional signal reading, considerable efforts have been made to solve these and other problems. Special attention is given to Figure 12 of U.S. Patent No. 9,386,241, where in order to avoid certain contamination of multiple integrated signals, a part of the active area of ​​the optical sensor is covered, and a complex arrangement of row shifting and horizontal reading can be performed to adapt to the limitations of existing imaging spectrometers.

[0053] The aforementioned problem can be illustrated by examining semiconductor processing applications, where IEP and OES signals may be combined in observation. Fig. 7A is a plot 700 of a typical IEP optical signal 620 combined with an OES optical signal 640. Here it is shown that the desired IEP signal is affected by contamination from the OES signal, but the overall characteristic shape of the IEP is evident. Figure 7B 710 is a plot of a typical identical IEP optical signal 620 combined with a second OES optical signal 630. Here is shown the much greater contamination of the desired IEP optical signal and the overall reduction in the ability to discern between the original signals due to dynamic range division. Notably, the appearance of an edge-like wavelength intensity pattern in the OES signal can be interpreted in the contaminated IEP signal as indicating reflectivity from the material layer.

[0054] The flash lamp can be used in a "double read" mode, where the flash lamp pulses are alternately turned on and then off (see, e.g., U.S. Patent 6,160,621, incorporated herein by reference) to remove a significant amount of signal contamination, but this mode of operation assumes that the OES signal is sufficiently slowly varying. If the OES signal is not sufficiently stable, then determination of an uncontaminated IEP signal is not possible using existing systems. With the optical sensor and spectrometer of the present invention, the active pixel area receiving the pulsed IEP flash lamp signal can be gated using a shutter function or other operating mode setting to exclude integration of optical input received from a period of time other than the several millisecond duration of the optical pulse.

[0055] Figure 7Cis a plot of a first representative OES optical signal 630 combined with a second OES optical signal 640. These signals may come from, for example Figure 1 The characteristics of OES optical signal 640 shown here are largely obscured by the presence of OES optical signal 630. Because OES signals are typically continuous in time, limitations of the physical readout structure of existing spectrometers and optical sensors will always contaminate the signal. Contamination levels below one percent are sufficient to make certain processes inoperable because the open area of ​​the process is very low. For example, a semiconductor etching process with a one percent open area may require an endpoint detection accuracy of one percent. These combined requirements suggest that changes of approximately 1:10,000 need to be detected, and any optical signal contamination needs to be less than this amount. The operation of the optical sensor and multi-mode configurable spectrometer of the present invention greatly reduces or completely removes contamination from reading the combined OES signal, and permits individual determination of the OES optical signals 630 and 640.

[0056] The multi-mode configurable spectrometer of the present invention provides flexibility of operation with respect to optical signal observation location, single / multiple chamber integration, single / multiple processing tool integration, single / multiple process variations, single type variations, and relative timing / synchronization of any of the foregoing. Several specific examples are described in Table 1. The description of modes and benefits listed in Table 1 is not meant to be exhaustive, and the benefits associated with any particular operating mode or signal type may also be associated with other operating modes or signal types.

[0057]

[0058] Table 1.

[0059] The signal types and benefits described in Table 1 can be associated with the specific structure and functionality of the optical sensor and multi-mode configurable spectrometer of the present invention. For example, in the dual OES mode (first row of Table 1), low signal crosstalk and contamination are achieved by the presence of dual shift registers and separate electrical signal output and conversion circuits. Other associations can be derived from the description herein, and several are described in more detail below.

[0060] In another example, the multi-mode configurable spectrometer of the present invention provides improved performance in an operating mode where one or more OES, IEP, or combined IEP and OES signals are monitored and the overall light level is very high. The current approach is to use the shortest integration time compatible with reading the signal from the optical sensor, and to subdivide the reading of the rows of active pixel area so that a portion of the active pixel area is small. This results in complex and slower operation of the spectrometer, in which multiple readings of the signal are performed, and can result in the signal being read but then not used due to saturation. The multi-mode configurable spectrometer of the present invention allows a shutter function to make the charge accumulation time short enough that saturation does not occur. At the same time, the data sampling rate can be kept low enough to allow high-quality digitization of the data, thereby increasing the overall signal-to-noise ratio and enhancing small signal detectability.

[0061] Relatedly, the combination of shutter functionality and independent readout of active pixel areas is beneficial when it is desired that two different optical signals can have different integration times. In one example of an OES, argon and halogen emissions produce high intensity signals in the 700 to 800 nm spectral range; while emissions from byproducts are typically weaker and fall in the UV to VIS range. A multi-mode configurable spectrometer can be configured for uniform data sampling rates (e.g., spectra per second) but independent integration times in different active pixel areas to provide suitable amplitude signals for all desired signals. Portions of each of these signals can be combined to provide composite spectra of increased utility and dynamic range for various independent wavelengths of interest for process control applications. In addition, automatic and independent gain control is permitted by setting the integration time of each independent active pixel area.

[0062] In addition, the disclosed design of the multi-mode configurable spectrometer emphasizes low light detection. The combination of high pixels and long sensor size permits the use of wider optical slits with equal wavelength resolution in the wavelength dispersion direction of current optical sensors. When used in conjunction with the multi-mode configurable spectrometer of the present invention, the high pixels of the optical sensor permit the use of a high slit and therefore permit greater overall light collection. In another combination, the use of a shutter function for active pixel area and active pixel area height allows for very wide dynamic range light collection. In the case of a multi-mode configurable spectrometer that includes a variable width slit, the slit width can be controlled as part of the operating mode of the multi-mode configurable spectrometer.

[0063] The additional operating modes of the optical sensor and multi-mode configurable spectrometer of the present invention are beneficial when applied to a pulsed plasma chamber. These modes include (but are not limited to): a) synchronization of optical signal collection with pulsed plasma; b) synchronization using a shutter; and c) time-resolved spectroscopy of pulsed plasma OES. For the synchronized operating mode, it is convenient to maintain the data interval at some convenient number (e.g., 20 Hz), even if the pulse frequency is not commensurate with that interval. The pulsed plasma frequency may be locked to an electronic shutter or other function of the optical sensor or conversion circuitry rather than to the data interval. There may be no frequency overlap, and there is no need to predetermine unusual integration times or use integration times that are not commensurate with the data interval. This operating mode may be achieved, for example, by Figure 1 Low latency communication support between the semiconductor process tool 105 and the sensor controller 150.

[0064] For time-resolved spectroscopy of pulsed plasma OES, an electronic shutter can be used to keep the exposure time shorter than the pulse period, and various parts of the pulse cycle can be sampled using appropriately timed delays between the plasma's pulse generator and activation of the electronic shutter. For example, if the exposure time of the active pixel area is 1 / 10 of the plasma pulse period, then 10 relative temporal shift readings of the optical signal can be used to represent the OES trend during different parts of the period. Optical data can be collected by repeatedly scanning the position of the exposure time within the period in steps of 1 / 10 of the period.

[0065] In IEP processes where very short duration flash light pulses are used to interrogate the workpiece, spectrometer systems typically utilize subtraction measurement pairs to isolate the IEP signal in the presence of OES light. Typically, IEP light pulses can be several microseconds, and typical integration times are multiple microseconds at a minimum, resulting in considerable IEP and OES signal contamination. Through selective timing and integration per active pixel area provided by the multi-mode configurable spectrometer of the present invention, an electronic shutter function can be synchronized to the IEP light pulses and have very short durations without affecting the overall data interval. Gated IEP light pulses can result in very significant combined IEP and OES signal reduction without the need for paired subtraction measurements. This change then permits a 2x greater measurement sampling rate.

[0066] Independent digitization of electrical signals from independent active pixel regions of an optical sensor of the multi-mode configurable spectrometer of the present invention permits relative adjustment of wavelength resolution and associated improvement of signal-to-noise ratio. For example, a first optical signal from an active pixel region may be configured for reading 1201 wavelength values ​​of a spectrum (200 to 800 nm, 0.5 nm resolution), but a second optical signal from an active pixel region may improve signal-to-noise ratio by improving binning of multiple neighboring pixels (summing of electrical signals) prior to digitization and providing a resulting lower resolution spectrum. Furthermore, independent digitization may be used to obtain a first optical signal from an active pixel region with full spectrum data, while a second optical signal from an active pixel region has only a few values ​​retained and other values ​​removed to avoid handling and storage of additional undesirable data.

[0067] Changes may be made in the optical measurement systems and subsystems described herein without departing from the scope thereof. For example, although certain examples are described in conjunction with semiconductor wafer processing equipment, it should be understood that the optical measurement systems described herein may be suitable for other types of processing equipment, such as roll-to-roll thin film processing, solar cell manufacturing, or any application in which high-precision optical measurement may be required. In addition, although the term "wafer" has been used herein when describing aspects of the present invention, it should be understood that other types of workpieces may be used, such as quartz sheets, phase shift masks, LED substrates, and other non-semiconductor processing related substrates and workpieces including solid, gaseous, and liquid workpieces.

[0068] The embodiments described herein are selected and described in order to best explain the principles and practical applications of the invention, and to enable persons of ordinary skill in the art to understand various modifications of the various embodiments of the invention as suitable for the particular use contemplated. The specific embodiments described herein are in no way intended to limit the scope of the invention, as they may be practiced in a variety of variations and environments without departing from the scope and purpose of the invention. Therefore, the invention is not intended to be limited to the embodiments shown, but should conform to the widest scope consistent with the principles and features described herein.

[0069] The flowchart and block diagram in the figure illustrate the architecture, functionality and operation of the possible implementation scheme of the system, method and computer program product according to various embodiments of the present invention. In this regard, each frame in the flowchart or block diagram may represent a part of a module, a fragment or a code, and the code includes one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative embodiments, the functions annotated in the frame may not occur in the order annotated in the figure. For example, two frames shown in succession may actually be executed substantially simultaneously, or the frames may sometimes be executed in reverse order, depending on the functionality involved. It should also be noted that each frame in the block diagram and / or flowchart illustration and the combination of frames in the block diagram and / or flowchart illustration may be implemented by a special hardware-based system or a combination of special hardware and computer instructions that perform a specified function or action.

[0070] As will be appreciated by those skilled in the art, the present invention or portions thereof may be embodied as methods, systems or computer program products. Thus, the features disclosed herein, or at least portions thereof, may take the form of a fully hardware embodiment, a fully software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects, all generally referred to herein as "circuits" or "modules". Portions of the disclosed features may be embodied in or performed by various processors, such as digital data processors or computers, wherein the computer is programmed or stores an executable program of a sequence of software instructions to perform one or more of the steps of the method. Thus, the features disclosed herein, or at least portions thereof, may take the form of a computer program product on a non-transitory computer-usable storage medium having a computer-usable program code embodied in the medium. The software instructions of such a program may represent an algorithm and may be encoded in a machine-executable form on a non-transitory digital data storage medium.

[0071] Thus, portions of the disclosed examples may involve computer storage products with non-transitory computer-readable media having program code thereon for performing various computer-implemented operations embodying a portion of an apparatus, device, or implementing the method steps recited herein. Non-transitory, as used herein, refers to all computer-readable media other than transient propagating signals. Examples of non-transitory computer-readable media include, but are not limited to, magnetic media (such as hard disks, floppy disks, and tapes), optical media (such as CD-ROM disks), magneto-optical media (such as floppy disks), and hardware devices (such as ROM and RAM devices) specifically configured to store and execute program code. Examples of program code include both machine code, such as produced by a compiler, and files containing higher-level code that can be executed by a computer using an interpreter.

[0072] The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention. As used herein, the singular forms "a / an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should be further understood that when the term "comprises / comprising" is used in this specification, it specifies the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0073] Those skilled in the art to which this application relates will appreciate that other and further additions, deletions, substitutions and modifications may be made to the described embodiments.

[0074] Various aspects of the invention may be claimed, including the apparatus, systems, and methods disclosed herein. Aspects disclosed herein include:

[0075] A. A multi-mode configurable spectrometer comprising: (1) an optical sensor configured to receive an optical input and convert the optical input into an electrical signal, wherein the optical sensor comprises a plurality of active pixel regions for converting the optical input into the electrical signal; and (2) a conversion circuit having a plurality of selectable conversion circuits, wherein the conversion circuit is configured to receive the electrical signal and convert the electrical signal into a digital output according to a selection of the selectable conversion circuits.

[0076] B. A method of operating a multi-mode configurable spectrometer. In one embodiment, the method includes: (1) converting an optical input into an electrical signal using at least one of a plurality of active pixel regions of an optical sensor; (2) providing the electrical signal to a conversion circuit having a plurality of selectable conversion circuits; and (3) converting the electrical signal into a digital output via one of the selectable conversion circuits.

[0077] C. An optical monitoring system comprising: (1) an optical interface configured to transmit light observed from a processing chamber; (2) a multi-mode configurable spectrometer configured to receive the light as an optical input from the optical interface. The multi-mode configurable spectrometer comprises: (2A) an optical sensor configured to convert the optical input into an electrical signal, wherein the optical sensor comprises a plurality of active pixel regions for converting the optical input into the electrical signal; (2B) a conversion circuit having a plurality of selectable conversion circuits, the conversion circuit being configured to receive the electrical signal and convert the electrical signal into a digital output according to a selection of the selectable conversion circuits; and (2C) a sensor controller configured to set an operating mode of the optical sensor based on the optical input and select one of the selectable conversion circuits to provide the digital output.

[0078] D. A multi-mode configurable spectrometer comprising: (1) an optical sensor comprising a plurality of active pixel regions for converting optical input into electrical signals and a shift register for each of the plurality of active pixel regions, wherein each of the active pixel regions is independently controllable; (2) a conversion circuit comprising a selectable conversion circuit, the conversion circuit being configured to receive the electrical signal and convert the electrical signal into a digital output according to a selected one of the selectable conversion circuits, wherein a unique set of at least four different selectable conversion circuits is connected to each of the shift registers, and the at least four different selectable conversion circuits include a circuit with a high-speed analog-to-digital converter, a circuit with a low-speed analog-to-digital converter, and a combination circuit; and (3) a sensor controller configured to change the operating mode of the optical sensor and the selected one of the selectable conversion circuits to provide the digital output based on the type of the optical input.

[0079] Each of the A, B, C and D aspects may be combined with one or more of the following additional elements:

[0080] Element 1: further comprising a sensor controller configured to direct the operation of the optical sensor and select at least one of the selectable conversion circuits to provide the digital output. Element 2: wherein the sensor controller is configured to set an operating mode of the optical sensor to direct its operation and is configured to select the at least one of the selectable conversion circuits based on the operating mode. Element 3: wherein the sensor controller is configured to dynamically set the operating mode and dynamically select the at least one of the selectable conversion circuits. Element 4: wherein the sensor controller is configured to dynamically set the operating mode and dynamically select the at least one of the selectable conversion circuits based on the optical input received by the optical sensor. Element 5: wherein the sensor controller includes a programmable integrated circuit configured to set the operating mode of the optical sensor. Element 6: wherein the sensor controller includes a processor configured to process the digital data. Element 7: wherein at least one of the selectable conversion circuits is a combinational circuit configured to receive signals from at least two of the plurality of active pixel regions and convert the signals into the digital output. Element 8: wherein the combination circuit includes an addition circuit, a difference circuit, a division circuit, a multiplication circuit, or an interleaving circuit. Element 9: it further includes a shift register for each of the plurality of active pixel regions, wherein each shift register has at least two different selectable conversion circuits of the selectable conversion circuits coupled thereto. Element 10: wherein the at least two different selectable conversion circuits of the selectable conversion circuits include a selectable conversion circuit with a high-speed analog-to-digital converter and a selectable conversion circuit with a low-speed analog-to-digital converter. Element 11: wherein at least one of the plurality of active pixel regions has a plurality of rows, the plurality of rows being independently processed to determine the digital output. Element 12: wherein the optical input includes a plurality of optical signals. Element 13: wherein the plurality of optical signals include optical signals of different types. Element 14: wherein the optical signal is an optical signal of a type selected from a list consisting of: a continuous optical signal, a pulsed optical signal, an optical emission spectroscopy (OES) signal, an interferometric endpoint (IEP) signal, a combined OES and IEP signal, and a combined continuous and pulsed optical signal. Element 15: wherein the optical input comprises a plurality of optical signals, and the sensor controller is configured to set the operating mode based on a type of at least one of the plurality of optical signals. Element 16: wherein the optical input comprises a plurality of optical signals, and the sensor controller is configured to set the operating mode based on a characteristic of at least one of the plurality of optical signals. Element 17: wherein the characteristic comprises a signal level, a signal-to-noise ratio, a sampling rate, a pulse rate, or a wavelength region.Element 18: wherein the optical input comprises a plurality of optical signals, and the sensor controller is configured to set the operating mode based on the type of one of the plurality of optical signals being OES. Element 19: wherein the optical input comprises a plurality of optical signals, and the sensor controller is configured to set the operating mode based on the type of one of the plurality of optical signals being IEP. Element 20: wherein the optical input comprises a plurality of optical signals, and the sensor controller is configured to set the operating mode based on the type of one of the plurality of optical signals being a combination of OES and IEP. Element 21: wherein the optical sensor further comprises a plurality of outputs for each of the plurality of active pixel regions. Element 22: wherein the digital output comprises a plurality of digital signals. Element 23: wherein the sensor controller is configured to direct the operation of the optical sensor by employing an electronic shutter for at least a portion of one of the active pixel regions. Element 24: further comprising receiving the optical input from a monitored semiconductor process and receiving a selection of an operating mode from an external system associated with the monitored semiconductor process. Element 25: wherein receiving the selection of the operating mode occurs before the monitored semiconductor process begins. Element 26: further comprising selecting an operating mode for the optical sensor and selecting said one of the selectable conversion circuits. Element 27: wherein at least one of said selecting said mode and said selecting said one is performed dynamically. Element 28: wherein a basis for selecting said mode and for selecting said one is selected from a list consisting of: a type of optical input, a characteristic of said optical input, a signal-to-noise ratio value of a digital output, and a data rate. Element 29: wherein the type of said optical input comprises a continuous optical signal, a pulsed optical signal, an optical emission spectroscopy (OES) signal, an interferometric endpoint (IEP) signal, a combined OES and IEP signal, and a combined continuous and pulsed optical signal. Element 30: wherein said selecting said one of the selectable conversion circuits comprises selecting a circuit from a list consisting of: a circuit having a high speed analog-to-digital converter, a circuit having a low speed analog-to-digital converter, and a combination circuit. Element 31: wherein the sensor controller is configured to receive the selection of the operating mode and the selection of said one of the selectable conversion circuits from an external system associated with the processing chamber. Element 32: wherein the sensor controller selects the operating mode and the selectable conversion circuitry based on a semiconductor process in the processing chamber that generates the light. Element 33: wherein the sensor controller dynamically selects different ones of different operating modes and the selectable conversion circuitry during the semiconductor process. Element 34: wherein the operating mode and the selectable conversion circuitry are selected based on a type of the light observed in the processing chamber.Element 35: wherein the type of light is selected from a list consisting of: a continuous optical signal, a pulsed optical signal, an optical emission spectroscopy (OES) signal, an interferometry endpoint (IEP) signal, a combined OES and IEP signal, and a combined continuous and pulsed optical signal. Element 36: wherein the multi-mode configurable spectrometer further comprises a shift register for each of the plurality of active pixel regions, wherein each of the shift registers has at least two different ones of the selectable conversion circuits coupled thereto. Element 37: wherein the at least two different ones of the selectable conversion circuits include a selectable conversion circuit having a high speed analog / digital converter and a selectable conversion circuit having a low speed analog / digital converter. Element 38: wherein the selectable conversion circuit further includes a combination circuit coupled to at least two of the shift registers.

Claims

1. A multi-mode configurable spectrometer, comprising: an optical sensor configured to receive an optical input and convert the optical input into an electrical signal, wherein the optical sensor comprises a plurality of active pixel areas for converting the optical input into the electrical signal; a conversion circuit having a plurality of selectable conversion circuits configured to receive the electrical signal and convert the electrical signal into a digital output according to a selected one of the selectable conversion circuits; as well as A sensor controller is configured to set a synchronous operating mode to direct operation of the optical sensor and select at least one of the selectable conversion circuits to provide the digital output based on the synchronous operating mode.

2. The multi-mode configurable spectrometer of claim 1 , wherein the optical input comprises at least one optical signal, and the synchronized operation mode is based on synchronization between the optical input collected by the optical sensor and an external control for generating the at least one optical signal.

3. The multi-mode configurable spectrometer of claim 2, wherein the at least one optical signal is derived from a pulsed plasma. 4 . The multi-mode configurable spectrometer of claim 3 , wherein the multi-mode configurable spectrometer further comprises an electronic shutter, and the synchronization is between the modulation of the pulsed plasma and the operation of the electronic shutter.

5. The multi-mode configurable spectrometer of claim 4, wherein the electronic shutter is configured to limit an exposure time for the collection relative to a period of the pulsed plasma.

6. The multi-mode configurable spectrometer of claim 4, wherein activation of the electronic shutter for the collection is delayed relative to the external control for generating the pulsed plasma.

7. The multi-mode configurable spectrometer of claim 3, wherein the synchronization is between modulation of the optical signal from the pulsed plasma and a data interval for the collection.

8. The multi-mode configurable spectrometer of claim 3, wherein at least one of a data interval and an integration time is adjusted based on the synchronization with the optical signal from the pulsed plasma. 9 . The multi-mode configurable spectrometer according to claim 2 , wherein the multi-mode configurable spectrometer further comprises an electronic shutter, and the sensor controller employs the electronic shutter to perform the synchronization.

10. The multi-mode configurable spectrometer of claim 9, wherein the optical input comprises at least one interferometry endpoint (IEP) signal and at least one optical emission spectroscopy (OES) signal, and the synchronization is between operation of the electronic shutter and the IEP signal.

11. The multi-mode configurable spectrometer according to claim 3, wherein the frequency of the pulsed plasma is synchronized to the conversion circuit of the multi-mode configurable spectrometer.

12. The multi-mode configurable spectrometer of claim 2, wherein the external control is a control signal that drives modulation of the optical input.

13. The multi-mode configurable spectrometer of claim 1, wherein the sensor controller is configured to dynamically set the synchronous operation mode and dynamically select the at least one of the selectable conversion circuits.

14. The multi-mode configurable spectrometer of claim 1, wherein the sensor controller is configured to dynamically set the synchronous operating mode and dynamically select the at least one of the selectable conversion circuits based on the optical input received by the optical sensor.

15. The multi-mode configurable spectrometer of claim 1, wherein the sensor controller is configured to dynamically select the synchronization operating mode based on the optical input during operation of the multi-mode configurable spectrometer.

16. A method of operating a multi-mode configurable spectrometer, comprising: converting an optical input into an electrical signal using at least one of a plurality of active pixel regions of an optical sensor, wherein the optical sensor operates according to a synchronized operating mode; providing the electrical signal to a conversion circuit having a plurality of selectable conversion circuits; selecting at least one of the selectable conversion circuits to provide a digital output based on the synchronous operating mode; and The electrical signal is converted to the digital output via the at least one of the selectable conversion circuits.

17. A method according to claim 16, wherein the optical input includes at least one optical signal from a pulsed plasma and the synchronous operation mode provides synchronization between the optical input collected by the optical sensor and an external control for generating the at least one optical signal and synchronization between the frequency of the pulsed plasma and the conversion circuit.

18. The method of claim 16, further comprising receiving the optical input and dynamically selecting the synchronization operating mode based on the optical input during the receiving.

19. An optical monitoring system, comprising: an optical interface configured to transmit light observed from the processing chamber; a multi-mode configurable spectrometer configured to receive the light from the optical interface as an optical input, the multi-mode configurable spectrometer comprising: an optical sensor configured to receive the optical input and convert the optical input into an electrical signal, wherein the optical sensor comprises a plurality of active pixel areas for converting the optical input into the electrical signal; a conversion circuit having a plurality of selectable conversion circuits configured to receive the electrical signal and convert the electrical signal into a digital output according to a selected one of the selectable conversion circuits; and A sensor controller is configured to set a synchronous operating mode to direct operation of the optical sensor and select at least one of the selectable conversion circuits to provide the digital output based on the synchronous operating mode.

20. The optical monitoring system of claim 19, wherein the optical input comprises at least one optical signal from a pulsed plasma and the synchronized operating mode provides synchronization between the optical input collected by the optical sensor and an external control for generating the at least one optical signal and synchronization between the frequency of the pulsed plasma and the conversion circuit.

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