An algorithm for accurately converting a wide range of photo signals into current

Abstract

Embodiments disclosed herein include a method for calibrating a tool for converting a photonic signal into an electrical signal. In one embodiment, the method includes connecting a calibration module to a calibrated current source, finding transfer functions for a plurality of modes by the calibration module, and storing the transfer functions in a look-up table.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority to U.S. Patent Application No. 17 / 862,278, filed on July 11, 2022, the entire content of which is incorporated herein by reference.

[0002] Embodiments relate to the field of semiconductor manufacturing, and more particularly, to processes and apparatus for calibrating pyrometers and emissometers.

Background Art

[0003] Temperature control is an important parameter for many processing operations in the semiconductor industry. For example, temperature control across the surface of a substrate (e.g., a silicon wafer) is important for obtaining process uniformity in applications such as thermal oxidation, thermal annealing, etc. Due to the complexity of semiconductor processing tools, temperature readings for such processes are generally implemented by non - contact temperature measurement systems. Non - contact measurement tools can include pyrometers, emissometers, etc. Generally, a temperature measurement tool includes a photodiode that receives an optical signal from the surface of the substrate being measured. For example, an infrared signal can be received by the photodiode.

[0004] Generally, the photocurrent is converted into a digital (electrical) signal. In semiconductor processing, the photocurrent has a large range. For example, the photocurrent can span multiple magnitudes (e.g., 10 magnitudes). In certain cases, the photocurrent can range from 10 -14 amperes (A) to 10 -4 A. The analog - to - digital converters (ADCs) used with such systems can have high resolution, but the ADCs are limited in sensitivity across the entire dynamic range of the ADC.

Summary of the Invention

[0005] The embodiments disclosed in this specification include a method for calibrating a tool for converting a photonic signal into an electrical signal. In one embodiment, the method includes connecting a calibration module to a calibrated current source, finding transfer functions for a plurality of modes by the calibration module, and storing the transfer functions in a look-up table.

[0006] In one embodiment, a tool for converting a photonic signal into an electrical signal is provided. In one embodiment, the tool includes a photodiode, a signal scaling module, an ADC, a selector module, and a current calculation module.

[0007] In one embodiment, a method for converting a photonic signal into an electrical signal includes receiving an optical signal by an ADC, selecting a mode based on the location of the optical signal within the dynamic range of the ADC, setting an integration time and range for the mode, and calculating a current based on a transfer function for the mode.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2A

Figure 2B

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[0009] The systems described herein include processes and apparatus for calibrating pyrometers and emitters. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. It will be apparent to one of ordinary skill in the art that the embodiments may be practiced without these specific details. In other instances, well-known aspects are not described in detail so as not to obscure the embodiments needlessly. Further, it should be understood that the various embodiments shown in the accompanying drawings are illustrative representations and are not necessarily drawn to scale.

[0010] As described above, non-contact temperature measurement solutions are used to provide improved process uniformity across the surface of a substrate. The non-contact temperature measurement solution can include an emitter and a pyrometer. Any reference herein to either an emitter or a pyrometer can be considered to also include both an emitter and a pyrometer. That is, the embodiments described herein are applicable to both emitters and pyrometers.

[0011] Generally, non-contact temperature measurement solutions include an analog-to-digital converter (ADC). The ADC can have high resolution but lacks sensitivity across the entire dynamic range. Thus, embodiments disclosed herein include a pyrometer and / or an emissometer solution that includes hardware, firmware, and / or software that enables an internal calibration process to be implemented. For example, the dynamic range of the ADC can be utilized in multiple modes. Each mode can include an integration time and a range. The integration time can be the integration time set for the ADC to record a value, and the range can be the value used by a signal scaling module. In one embodiment, each mode can be associated with a transfer function that includes two or more coefficients (e.g., coefficients k and b). When a particular mode is selected, the associated transfer function coefficients are used to calculate a calibrated current. For example, coefficient k can be multiplied by the ADC value, and coefficient b can be an offset. In some embodiments, a dark current value can also be used to more accurately measure temperature.

[0012] Referring now to FIG. 1, a diagram of a processing system 100 according to one embodiment is shown. Processing system 100 can include a pyrometer 120 and a thermal body 121. Pyrometer 120 uses a non-contact measurement process to measure the temperature of thermal body 121. For example, thermal energy 122 (e.g., infrared electromagnetic radiation) can be emitted by thermal body 121 and propagated toward pyrometer 120. Pyrometer 120 can include one or more photodiodes to convert the photothermal energy 122 into a digital signal that can be used to calculate the temperature of thermal body 121. As will be described in more detail below, pyrometer 120 can include an integrated calibration module to properly calibrate pyrometer 120.

[0013] In one embodiment, the thermal body 121 may include any number of components used in a semiconductor manufacturing process. For example, the thermal body 121 may be a semiconductor substrate such as a silicon wafer, or any other semiconductor wafer. In other embodiments, the thermal body 121 may be a glass substrate, a ceramic substrate, etc. The temperature of the components of the semiconductor processing tool can also be measured by the pyrometer described herein. For example, the thermal body 121 may include a chamber lid, a chucking surface, etc. More generally, the thermal body 121 can be any object whose temperature is desired to be measured. That is, the pyrometer 120 disclosed herein is not limited to a semiconductor processing environment.

[0014] In one embodiment, the pyrometer 120 can be integrated in a semiconductor processing tool. For example, a rapid thermal processing (RTP) chamber, such as a thermal oxidation chamber, can utilize one or more pyrometers 120. It should be understood, however, that any type of semiconductor processing tool can benefit from the non-contact temperature measurement provided by the pyrometer 120 described herein. An example of a particular processing chamber that utilizes one or more pyrometers 120 will be shown in more detail below with respect to FIG. 7.

[0015] Referring now to FIG. 2A, a schematic diagram of a pyrometer 220 according to one embodiment is shown. In one embodiment, the pyrometer 220 may include a pair of photodiodes 223 A and 223 B . The photodiodes 223 may be suitable for converting an optical signal into an electrical signal. For example, the photodiodes 223 A and 223 B can be configured to detect infrared electromagnetic radiation emitted by a thermal body, such as a semiconductor wafer.

[0016] In one embodiment, the photodiode 223 can be coupled to a measurement system. The measurement system can include a signal scaling module 226 and an ADC 227. In the illustrated embodiment, a single scaling module 226 and ADC 227 are shown. However, in other embodiments, each photodiode 223 can be coupled to a different signal scaling module 226 and ADC 227. In one embodiment, the signal scaling module 226 can be responsible for changing (e.g., amplifying) the signal provided by the photodiode 223 before the signal reaches the ADC 227. The ADC 227 can have any suitable ADC architecture, sampling rate, dynamic range, etc.

[0017] The pyrometer 220 can further include a calibration module 228. That is, the calibration module 228 can be integrated into the pyrometer 220 itself. Generally, the calibration module 228 uses the switch 224 A or 224 B by engaging it with a calibrated current source 225. The calibrated current source 225 can include a battery or the like. The calibrated current source 225 can then be used to construct a transfer function for each operating mode of the ADC 227. For example, each mode can include an integration time for the ADC 227 and a range for the signal scaling module 226. The transfer function can include two coefficients that are used to calculate an accurate temperature report. After calibration is complete, the switches 224 A and 224 B can be switched off from the calibrated current source 225 to return the input to the signals from the photodiodes 223 A and 223 B A more detailed description of the calibration system and the method for calibrating the pyrometer 220 will be described in more detail below.

[0018] In one embodiment, the thermometer 220 may further include a selector 229. The selector 229 may be used to select the mode used to operate the ADC 227 and the signal scaling module 226. The selector 229 may select the mode based on different parameters. In one embodiment, the selector 229 is the first photodiode 223 A to provide the best performance for the ADC 227 coupled thereto, or the second photodiode 223 B to provide the best performance for the ADC 227 coupled thereto. In other embodiments, the selector 229 may use either the first photodiode 223 A or the second photodiode 223 B For example, either photodiode 223 having the highest signal strength or the lowest signal strength may be used to select the desired mode.

[0019] In one embodiment, the thermometer 220 may also include a calculator module 230. The calculator module 230 may use the transfer function for a given mode to generate an accurate report of the temperature observed by the thermometer. In one embodiment, the transfer function is stored in a look-up table or memory (not shown) on the thermometer 220. The transfer function may include a first coefficient (k) that is multiplied by the reading of the ADC 227 and a second coefficient (b) that is an offset value. The calculator module 230 may take the form of I = k*ADC + b.

[0020] In some embodiments, the dark current value may also be stored in a look-up table or memory. The dark current may be subtracted from the calculated value to determine the exact value of the temperature. In such embodiments, the calculator module 230 may take the form of I = k*ADC + b - dark current. The dark current may be the value of the current flowing through the pyrometer 220 when the pyrometer 220 is in a dark environment. That is, in the case of the photodiode 223 adjusted to detect infrared radiation, the photodiode 223 may be placed in an enclosure that is opaque to infrared radiation in order to measure the dark current. If the dark current is not subtracted, the noise in the system may result in inaccurate temperature readings. The dark current may be mode-independent.

[0021] Next, referring to FIG. 2B, a schematic diagram of a pyrometer 220 according to an additional embodiment is shown. The pyrometer 220 in FIG. 2B may be substantially similar to the pyrometer 220 in FIG. 2A, except for the number of photodiodes 223. Two photodiodes 223 A and 223 B are replaced by only a single photodiode 223. An example of one photodiode 223, as well as two photodiodes 223 A and 223 B are shown, but it should be understood that the pyrometer 220 may have any number of photodiodes 223 (e.g., one or more photodiodes).

[0022] In the illustrated embodiment with a single photodiode 223, the selector 229 is less complex. Instead of needing to select between two photodiodes 223, the selector 229 only needs to consider a single photodiode 223. Thus, the mode selected by the selector 229 will optimize the performance for the single photodiode 223. Further, since only a single photodiode 223 is provided, the connections between components are reduced because only a single channel is needed.

[0023] Next, referring to FIG. 3, a process flow diagram of a process 340 for calibrating a thermometer according to one embodiment is shown. In one embodiment, the thermometer being calibrated may include one or more photodiodes, such as the example described in more detail above. Further, calibration hardware, firmware, and / or software may be integrated within the thermometer.

[0024] In one embodiment, process 340 may begin with operation 341, which includes connecting a calibration module to a calibrated current source. In one embodiment, the input line to the calibration module may be implemented by a switch. During the calibration operation, the switch may be positioned such that the input line is electrically coupled to the calibrated current source. In one embodiment, the calibrated current source is a current source having a known current. In one embodiment, the calibrated current source may be implemented using a battery integrated with the thermometer. However, in other embodiments, the current source may be provided external to the thermometer. In one embodiment, the calibrated current source may provide a single current value. In other embodiments, the calibrated current source may be configured to provide a plurality of different current values. The use of the calibrated current source enables the calibration module to know what the input current should be so that the effects (such as noise) due to the thermometer's circuit can be determined.

[0025] In one embodiment, process 340 may continue with operation 342, which includes finding transfer functions for a plurality of modes. In one embodiment, each mode may correspond to a pairing of an integration time for the ADC and a range for the signal scaling module. The plurality of modes are used to improve the sensitivity of the ADC across the dynamic range of the ADC. The selector will select a particular mode depending on where in the dynamic range of the ADC the signal is. In one embodiment, the transfer function for each mode may include a pair of coefficients. The first coefficient (k) will be multiplied by the ADC output, and the second coefficient (b) is an offset value.

[0026] In one embodiment, the transfer function can be calculated by any known processing operation. For example, the transfer function can be a pair of coefficients (k and b) such that the measured current equals the current of a calibrated current source. In this way, the effects of circuits, modules, and components on the output can be taken into account to provide a more accurate temperature measurement. Further, it should be understood that circuits, modules, and components can have different effects depending on the amount of current provided through the system. Thus, different modes are used to calibrate the entire dynamic range of the ADC.

[0027] In one embodiment, process 340 can continue with operation 343, which includes storing the transfer function in a look-up table. In one embodiment, the transfer function can be stored in a look-up table provided in memory accessible to the thermometer. For example, a memory die or other memory architecture can be integrated into the thermometer. That is, the source of the memory can be provided on a board that houses the electronics for the thermometer.

[0028] Referring now to FIG. 4, a process flow diagram of a process 450 for measuring temperature by a thermometer according to one embodiment is shown. In one embodiment, the thermometer can be similar to any of the thermometers described in more detail herein. More specifically, the thermometer can be a thermometer that includes an integrated calibration module to provide an improved calibration of the thermometer.

[0029] In one embodiment, process 450 may begin with operation 451, which includes receiving an optical signal by an ADC. In one embodiment, the optical signal may first be processed by a photodiode. The photodiode may convert the optical signal (e.g., an infrared signal) into an electrical signal. The electrical signal may then be passed through a signal scaling module before reaching the ADC. In one embodiment, the pyrometer includes a single photodiode. In other embodiments, the pyrometer may include two or more photodiodes. In such embodiments, each photodiode may report the electrical signal to a different channel of the ADC or to two different ADCs.

[0030] In one embodiment, process 450 may continue with operation 452, which includes selecting a mode based on the location of the electrical signal within the dynamic range of the ADC. That is, the dynamic range of the ADC may be segmented into a plurality of individual sections. The segmentation of the dynamic range allows different parameters to be applied to the signal in order to optimize the accuracy and sensitivity of the ADC. In one embodiment, the mode may include an integration time for the ADC and a range for the signal scaling module.

[0031] In one embodiment, the mode may be selected based on the output of a channel of the ADC coupled to the first photodiode or based on the output of a channel of the ADC coupled to the second photodiode. In other embodiments, the mode may be selected based on which ADC channel is the highest or the lowest. It should be understood that separate channels of a single ADC are contemplated herein, but similar embodiments may be used when each photodiode has a separate ADC.

[0032] In one embodiment, process 450 may continue with operation 453, which includes setting the integration time and range for the mode. In one embodiment, the integration time may be applied to the ADC and the range may be applied to the signal scaling module. The values for the integration time and range may be stored in a memory integrated into the pyrometer.

[0033] In one embodiment, process 450 may continue with operation 454, which includes calculating a current based on a transfer function for a mode. The transfer function for the mode may be stored in a look-up table. The transfer function may be determined using a calibration process, such as the process described in more detail above. The transfer function may include a pair of coefficients (k and b). In one embodiment, the calculation may include using those coefficients to calculate the current. For example, the equation may be as follows: I = k*ADC + b.

[0034] In some embodiments, the calculation may further include adjusting for dark current in the system. In such embodiments, the equation may be as follows: I = k*ADC + b - dark current. The dark current value may also be stored in a look-up table. The dark current may be determined during calibration of the pyrometer, during assembly of the pyrometer, or at any other time.

[0035] Referring now to FIG. 5, a plan view of a pyrometer 520 according to one embodiment is shown. In one embodiment, the pyrometer 520 may include a board 519. The board 519 may be a printed circuit board or the like. In one embodiment, a plurality of modules and / or components may be coupled to the board 519.

[0036] In one embodiment, a photodiode 523 may be provided on the board 519. The photodiode 523 may include optics for detecting an optical signal (e.g., an infrared electromagnetic radiation signal) from a thermal body. In the illustrated embodiment, a single photodiode 523 is shown. However, it should be understood that embodiments may include two or more photodiodes 523. The photodiode 523 converts the optical signal into an electrical signal.

[0037] In one embodiment, the pyrometer 520 may further include a signal scaling module 526 and an ADC 527. The signal scaling module 526 and the ADC 527 may be used to convert an electrical analog signal into a digital signal that can be used to calculate the current obtained by the photodiode 523. The signal scaling module 526 and the ADC 527 may include multiple channels to accommodate multiple photodiodes 523.

[0038] In one embodiment, the pyrometer 520 may include a mode selector module 529. The mode selector module 529 may be used to select an appropriate mode to accurately measure the signal from the photodiode 523. The mode may include an integration time for the ADC 527 and a range for the signal scaling module 526. The integration time for the ADC 527 and the range for the scaling module 526 may be stored in a look-up table accessible to the mode selector 529. For example, the look-up table may be provided in the memory 531.

[0039] In one embodiment, the pyrometer 520 may further include a calibration module 528. The calibration module 528 is used to calibrate the signal obtained from the photodiode 523. The calibration module 528 may generate multiple transfer functions. Each transfer function may be associated with one of the modes described above. The transfer function may include a pair of coefficients (k and b). Those coefficients may be used by the calculator module 530 to calculate a calibrated value of the current using an equation, such as those described in more detail above.

[0040] In one embodiment, the calibration module 528 may be configured to be selectively coupled to the calibration current source 525. The calibration current source 525 may provide a known value of current to assist in the calibration of the thermometer 520. Specifically, the calibration module 528 receives from the system an input current having a known current from the calibration current source 525 and passing through the circuit of the thermometer 520. Then, the difference between the calibration current and the input current may be determined, and the calibration module 528 generates coefficients for the transfer function to convert the input current to a value equal to the calibration current. In one embodiment, the calibration current source 525 provides a single current. In other embodiments, the calibration current source 525 may be capable of providing multiple different current values.

[0041] Referring now to FIG. 6, a process flow diagram of a process 660 for assembling a thermometer according to one embodiment is shown.

[0042] In one embodiment, process 660 may begin with operation 661, which includes assembling the board without a photodiode. The board may include components or modules such as a signal scaling module, an ADC, a calibration module, a calibration current source, a selector module, and a calculator module.

[0043] In one embodiment, process 660 may continue with operation 662, which includes calibrating the board. The calibration may be similar to any of the calibration processes described in more detail above. For example, the calibration current source may supply an input current having a known value passing through the electronics to the calibration module. The calibration module detects the level of the current and compares that level to a known calibration current level. The calibration module then produces a transfer function having coefficients (k and b) used to convert the measured current to a known calibration current. The transfer function is then stored in a look-up table for use during operation of the thermometer.

[0044] In one embodiment, process 660 may continue with operation 663, which includes determining the dark current for the board. The dark current may be measured by supplying a temporary photodiode to the board and measuring the resulting current provided through the system when the pyrometer is placed in a dark enclosure (e.g., opaque to infrared radiation). The value of the dark current may be stored in a look-up table of the pyrometer. After the dark current is determined, the temporary photodiode may be removed. In one embodiment, the dark current is mode independent.

[0045] In one embodiment, process 660 may continue with operation 664, which includes assembling a photodiode to the board. The photodiode may be attached to the board at a physical location different from where the remainder of the board is assembled. For example, a partially assembled board may be assembled at a first facility, and the photodiode may be assembled to the board at a second facility.

[0046] In one embodiment, process 660 may continue with operation 665, which includes calibrating the board a second time. In one embodiment, the second calibration may be used to inspect the electronics and ensure that everything is functioning properly. The second calibration process may, in some embodiments, not use a calibration module.

[0047] Referring now to FIG. 7, a cross-sectional view of a processing chamber 770 according to one embodiment is shown. In one embodiment, chamber 770 may comprise any type of semiconductor manufacturing chamber that may require precise substrate temperature control. In the illustrated embodiment, a chamber 770 without plasma capabilities is shown. However, it should be understood that chamber 770 may also be equipped with the ability to use plasma to implement various processing regimes.

[0048] In one embodiment, the chamber 770 may include a chamber body 710. The chamber body 710 may include any suitable material, such as stainless steel. In one embodiment, a coating (not shown) may be provided on the inner surface of the chamber body 710. For example, the coating may be a chamber seasoning or a protective layer. In one embodiment, gas 711 may enter the chamber 770 through a first portion of the chamber body 710, and gas 712 may exit the tool through a second portion of the chamber body 710. Although gases 711 and 712 entering and exiting through the chamber body 710 are shown, it should be understood that the gases may enter or exit the chamber through any portion of the chamber 770 depending on the type of chamber 770 being used.

[0049] In one embodiment, a substrate support 705 and a susceptor 707 are provided in the chamber. The substrate support 705 and the susceptor 707 are configured to hold and / or fix the substrate 709. For example, the substrate 709 may be a semiconductor substrate, such as a silicon wafer. The substrate 709 may have any suitable form factor. For example, the diameter of the substrate 709 may be 300 mm, 450 mm, or any standard wafer form factor. Additionally, other substrates 709 may be used in the chamber 770. For example, in some embodiments, glass substrates, ceramic substrates, etc. may also be used. In one embodiment, the substrate support 705 and the susceptor 707 may be configured to rotate. The rotation enables improved temperature uniformity across the substrate 709.

[0050] The susceptor 707 can include any type of chucking architecture to fix the substrate 709. In some embodiments, the susceptor 707 can include an electrostatic chucking (ESC) architecture. In such embodiments, the substrate 709 is fixed to the susceptor 707 by electrostatic force. Other embodiments can include a vacuum chucking architecture for the susceptor 707. In one embodiment, the susceptor 707 and the substrate support 705 can include a quartz material or another material that is at least substantially transparent to infrared radiation. Accordingly, the temperature of the back surface of the substrate 709 can be obtained by the pyrometer 706.

[0051] In one embodiment, the chamber 770 can include a lid 715. The lid 715 is sometimes referred to as a chamber dome. It should be understood that although shaped as a dome, the lid 715 can have any architecture (e.g., a flat surface, etc.). The lid 715 can be formed from a material that is at least substantially transparent to infrared radiation. For example, the lid 715 can include quartz or the like.

[0052] In one embodiment, the chamber 770 can also include a bottom lid 717. The bottom lid 717 can cover the bottom surface of the chamber 770. The bottom lid 717 can include a material that is at least substantially transparent to infrared radiation. Accordingly, the pyrometer 706 on the bottom side of the chamber 770 can be used to measure the temperature of the bottom surface of the substrate 709. In one embodiment, the bottom lid 717 can be coupled to the substrate support 705. More specifically, the substrate support 705 can pass through the bottom lid 717. The bottom lid 717 is coupled to the substrate support 705 in a configuration that allows the substrate support 705 to rotate freely.

[0053] In one embodiment, a plurality of lamps 735 may be provided outside the internal volume of the chamber 770. The internal volume of the tool may refer to the volume defined by the lid 715, the chamber body 710, and the bottom lid 717. That is, the lamps 735 are not provided within the internal volume of the chamber 770 where substrate processing is implemented. In one embodiment, a plurality of pyrometers 706 may be provided through the bottom lid 717. The pyrometer 706 may be focused on the back surface of the substrate 709. In one embodiment, the pyrometer 706 may be similar to any of the pyrometers described in more detail herein. For example, the pyrometer 706 may include an internal calibration module.

[0054] Next, referring to FIG. 8, a block diagram of an exemplary computer system 800 of a processing tool according to one embodiment is shown. In one embodiment, the computer system 800 is coupled to the processing tool and controls the processing in the processing tool. The computer system 800 may be connected (e.g., networked) to other machines in a local area network (LAN), intranet, extranet, or the Internet. The computer system 800 may operate in the capacity of a server machine or a client machine in a client-server network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. The computer system 800 may be a personal computer (PC), tablet PC, set-top box (STB), personal digital assistant (PDA), cellular phone, web appliance, server, network router, switch or bridge, or any machine capable of executing a set (serial or otherwise) of instructions that specify actions to be taken by that machine. Further, although only a single machine is shown for the computer system 800, the term "machine" is also to be construed to include any collection of machines (e.g., computers) that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies described herein.

[0055] Computer system 800 may include a computer program product, or software 822, having a non-transitory machine-readable medium storing instructions that can be used to program computer system 800 (or other electronic device) to perform a process according to an embodiment. A machine-readable medium includes any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer). For example, a machine-readable (e.g., computer-readable) medium includes a machine (e.g., computer) readable storage medium (e.g., read only memory ("ROM"), random access memory ("RAM"), magnetic disk storage media, optical storage media, flash memory devices, etc.), a machine (e.g., computer) readable transmission medium (electrical, optical, acoustic, or other form of propagated signal (e.g., infrared signal, digital signal, etc.)), and the like.

[0056] In one embodiment, computer system 800 includes a system processor 802, a main memory 804 (e.g., dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM), flash memory, Rambus DRAM (RDRAM), etc. or read only memory (ROM)), a static memory 806 (e.g., flash memory, static random access memory (SRAM), etc.), and a secondary memory 818 (e.g., a data storage device) that communicate with each other via a bus 830.

[0057] The system processor 802 represents one or more general-purpose processing devices, such as a micro-system processor, a central processing unit, etc. More specifically, the system processor can be a complex instruction set computing (CISC) micro-system processor, a reduced instruction set computing (RISC) micro-system processor, a very long instruction word (VLIW) micro-system processor, a system processor implementing other instruction sets, or a system processor implementing a combination of instruction sets. The system processor 802 can also be one or more dedicated processing devices, such as an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a digital signal system processor (DSP), a network system processor, etc. The system processor 802 is configured to execute processing logic 826 for performing the operations described herein.

[0058] The computer system 800 may further include a system network interface device 808 for communicating with other devices or machines. The computer system 800 may also include a video display unit 810 (e.g., a liquid crystal display (LCD), a light-emitting diode display (LED), or a cathode ray tube (CRT)), an alphanumeric input device 812 (e.g., a keyboard), a cursor control device 814 (e.g., a mouse), and a signal generation device 816 (e.g., a speaker).

[0059] The secondary memory 818 may include a machine-accessible storage medium 832 (or more particularly, a computer-readable storage medium) in which one or more sets of instructions (e.g., software 822) embodying any one or more of the methodologies or functions described herein are stored. The software 822 may also be present, in whole or in part, within the main memory 804 and / or within the system processor 802 during execution of the software 822 by the computer system 800, and the main memory 804 and the system processor 802 also constitute a machine-readable storage medium. The software 822 may further be transmitted or received over the network 820 via the system network interface device 808. In one embodiment, the network interface device 808 may operate using RF coupling, optical coupling, acoustic coupling, or inductive coupling.

[0060] Although the machine-accessible storage medium 832 is shown as a single medium in the exemplary embodiments, the term "machine-readable storage medium" should be interpreted to include a single medium or multiple media (e.g., a centralized or distributed database, and / or associated caches and servers) that store one or more sets of instructions. The term "machine-readable storage medium" should also be interpreted to include any medium that is capable of storing or encoding a set of instructions for machine execution and that causes a machine to perform any one or more of the methodologies. The term "machine-readable storage medium" should therefore be interpreted to include, without limitation, solid state memories, and optical and magnetic media.

[0061] In the foregoing specification, specific exemplary embodiments have been described. It will be apparent that various modifications may be made thereto without departing from the scope of the following claims. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a limiting sense.

Claims

1. A method for calibrating a tool for converting a photonic signal into an electrical signal, comprising: connecting a calibration module to a calibrated current source; finding transfer functions for a plurality of modes by the calibration module; storing the transfer functions in a look-up table. A method as described above.

2. The method according to claim 1, wherein each mode of the plurality of modes includes an integration time and a range.

3. The method according to claim 2, wherein the integration time is supplied to an ADC in the tool, and the range is supplied to a signal scaling module in the tool.

4. The method according to claim 1, wherein the transfer function includes a first coefficient and a second coefficient, the first coefficient is multiplied by an ADC value, and the second coefficient is an offset value.

5. The method according to claim 1, wherein the calibration further includes finding the dark current of the tool.

6. The method according to claim 1, wherein the tool is a pyrometer or an emissometer.

7. A tool for converting a photonic signal into an electrical signal, comprising: a photodiode; a signal scaling module; an ADC; a selector module; a current calculation module. A tool as described above.

8. The tool according to claim 7, wherein the selector module is configured to select a mode for operating the ADC and the signal scaling module.

9. The tool according to claim 8, wherein the mode includes an integration time for the ADC and a range for the signal scaling module.

10. A second photodiode The tool according to claim 7, further comprising.

11. The tool according to claim 10, wherein the selector module is configured to select a mode for operating the ADC and the scaling module based on the ADC value of the photodiode or the ADC value of the second photodiode.

12. The tool according to claim 10, wherein the selector module is configured to select a mode for operating the ADC and the scaling module based on which ADC value is higher, and the ADC value includes a first ADC value for the photodiode and a second ADC value for the second photodiode.

13. Calibration module The tool according to claim 7, further comprising

14. An internal source of calibrated current The tool according to claim 13, further comprising

15. The tool according to claim 14, wherein the calibration module calibrates the tool when the calibration module is connected to the internal source of the calibrated current.

16. The tool according to claim 7, wherein the tool is a pyrometer or an emissometer.

17. A method for converting a photonic signal into an electrical signal, comprising: Receiving an optical signal by an ADC; Selecting a mode based on the location of the optical signal within the dynamic range of the ADC; Setting an integration time and a range for the mode; Calculating a current based on a transfer function for the mode and including.

18. The method according to claim 17, wherein the transfer function includes a first coefficient and a second coefficient stored in a look-up table.

19. The method according to claim 17, wherein calculating the current further includes subtracting a dark current from the current.

20. Further comprising receiving a second optical signal by the ADC, and selecting the mode further includes selecting the mode based on the second optical signal or the optical signal according to which optical signal is larger. The method according to claim 17.

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