Cryogenic measurement of semiconductor substrates

Abstract

Examples described herein generally relate to apparatuses and methods for rapid thermal processing (RTP) of substrates. The present disclosure discloses a wide range of pulsed radiation sources to measure a RTP chamber from low temperature to high temperature, each pulsed radiation source at a discrete wavelength, the pulsed radiation sources being used in a low temperature interval prior to using one laser at the discrete wavelength for higher temperatures. In another example, a single laser is used for low temperature intervals and higher temperatures. Such methods have a wide range of detection from low temperature to high temperature in RTP chambers having different substrate types.

Description

Technical Field

[0001] Embodiments described herein generally relate to apparatus and methods for high temperature measurement of extended temperatures, which can be used to process semiconductor wafers. More specifically, the apparatus and methods described herein relate to rapid thermal processing (RTP) of semiconductor substrates, and high temperature measurement techniques for extended temperatures (including cryogenics) in RTP. Background Art

[0002] Rapid thermal processing (RTP) is a term applied to several types of thermal processes, including annealing, dopant activation, oxidation, and nitridation, which are typically performed at relatively high temperatures above about 1000°C. RTP can further be applied to etching and chemical vapor deposition in the presence of precursor or etching gases. In conventional manner, these processes are performed in an RTP chamber at temperatures between 500°C and 800°C. RTP typically depends on an array of high-intensity incandescent lamps mounted in a lamp head and directed toward the substrate being processed. The lamps can be turned on and off quickly, and a large portion of their radiation can be directed toward the substrate. Thus, the substrate can be quickly heated to the desired thermal state.

[0003] Transmission pyrometry is a common mode of evaluating the thermal state of a substrate. Thermal processing chambers typically expose substrates to intense, incoherent or coherent radiation to raise the substrate temperature (either the temperature of the entire substrate or a portion or surface area of ​​the substrate). The radiation used to heat the substrate can create a strong background radiation environment in the chamber.

[0004] Radiation is used in transmission pyrometry applications to assess the thermal state of a substrate, as radiation with different wavelengths can be distinguished from background radiation in the chamber. Lasers are often used, as they offer the opportunity to select a specific wavelength that is best suited to the substrate. Lasers produce coherent radiation that, when transmitted through the substrate, can indicate the thermal state of the substrate, which can be registered as a temperature. The transmitted radiation can be detected by the pyrometer in comparison to the source radiation, and the results correlated to infer the substrate thermal state.

[0005] Current pyrometers use two detectors to sum the radiation intensity of two bands emitted by one or more lasers, and then use a temperature lookup table to relate the quotient of the two intensities to temperature. In an ideal situation (such as a black body), the emissivity would cancel out. In practice, the emissivity is provided by the manufacturer and typed in by the operator or assumed to be uniform. However, the emissivity is often unknown or varies. In addition, pyrometers that rely on ratios are susceptible to noise because the intensity difference of the two wavelengths is often relatively small.

[0006] However, thermal noise, or electrical fluctuations generated by random thermal motion of electrons, chamber heat sources such as illumination lamps, and substrate emissions, can degrade the accuracy and precision of conventional transmission pyrometry methods using high resistivity substrates. Additionally, current transmission pyrometry apparatus and methods describe solutions to thermal noise, but such solutions are limited to silicon substrates and typically require the use of multiple lasers at multiple wavelengths for the duration of the method.

[0007] Therefore, there is a need for improved apparatus and methods for reliable transmission pyrometry from cryogenic to high temperatures that can operate in a wider range of semiconductor substrates. Summary of the invention

[0008] Examples described herein generally relate to apparatus and methods for rapid thermal processing (RTP) of substrates. The present disclosure discloses pulsed radiation sources to measure a wide range from low temperature to high temperature in an RTP chamber, each pulsed radiation source is at a discrete wavelength and is used for the low temperature interval before a single laser at a discrete wavelength is used for the higher temperature. In another example, a single laser is used for the low temperature interval and the higher temperature.

[0009] This will be completed after final approval of the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] So that the manner in which the above-described features of the present disclosure may be understood in detail, a more particular description of the disclosure, briefly summarized above, may be obtained by reference to examples, some of which are illustrated in the accompanying drawings. It should be noted, however, that the drawings illustrate only typical examples of the disclosure and, therefore, should not be considered limiting of the scope of the disclosure, as the disclosure may admit to other equally effective examples.

[0011] Figure 1 is a partial schematic diagram of a rapid thermal processing (RTP) chamber including two or more lasers according to an exemplary embodiment of the present disclosure.

[0012] Figure 2A is a partial schematic diagram of an RTP chamber having a radiation source including a laser according to an exemplary embodiment of the present disclosure.

[0013] Figure 2B for Figure 2A A top view of a portion of the honeycomb array inside the lamp housing of the RTP chamber.

[0014] Figure 3 According to an exemplary embodiment of the present disclosure, a flow chart of a dual-wavelength temperature measurement method is shown.

[0015] Figure 4 According to an example of the present disclosure, a flow chart of a single-wavelength temperature measurement method is shown.

[0016] Figure 5 A flow chart is depicted illustrating example operations performed by one or more processors in a controller of an RTP chamber in accordance with one or more exemplary embodiments of the present disclosure.

[0017] Figure 6 A flow chart is depicted illustrating example operations performed by one or more processors in a controller of an RTP chamber in accordance with one or more exemplary embodiments of the present disclosure.

[0018] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. In addition, elements of one example may be advantageously adapted for use in other examples described herein. DETAILED DESCRIPTION

[0019] Examples described herein generally relate to apparatus and methods for rapid thermal processing (RTP) of substrates. The present disclosure discloses radiation sources to measure a wide range from low temperature to high temperature in an RTP chamber. In one example, two or more lasers, each at a discrete wavelength, are used in the low temperature interval before a single laser at a discrete wavelength is used at a higher temperature. In another example, a single laser is used for the low temperature interval and the higher temperature.

[0020] Figure 1 FIG. 1 is a partial schematic diagram of a rapid thermal processing (RTP) chamber 100 according to an example of the present disclosure. The chamber 100 generally includes a lamp assembly 110, a chamber body 120, and a substrate support assembly 130. For clarity, the chamber 100 has been cross-sectioned and only the Figure 1 An upper portion of the chamber body 120 is shown in FIG.

[0021] The lamp assembly 110 includes a plurality of lamps 111, each of which is positioned within a reflective tube 112. The lamps 111 may be incandescent lamps, such as tungsten halogen lamps, or other high output lamps, such as discharge lamps. The reflective tubes 112 together form a honeycomb array 113 within a water-cooled housing 114. In one example, a very thin window 115 forms the bottom surface of the lamp assembly 110, thereby separating the lamp assembly 110 from the vacuum that is typically present in the chamber 100. In another example, the window 115 is a separate element. The window 115 is generally made of or coated with any material that is resistant to the processing environment and can transmit the selected radiation. The lamp assembly 110 is attached to the upper surface of the chamber body 120 in a vacuum-tight manner.

[0022] The chamber body 120 includes a wall and a bottom plate of the chamber 100. A substrate opening 121 and an exhaust opening 122 are formed through the wall of the chamber body 120. A substrate is transferred into or removed from the chamber 100 through the substrate opening 121, and a vacuum pump (not shown) evacuates the chamber 100 through the exhaust opening 122. A slit valve or a gate valve (not shown) may be used to seal the substrate opening 121 and the exhaust opening 122 when necessary.

[0023] The substrate support assembly 130 defining the processing plane is confined within the chamber body 120 and includes an edge support 131, a rotatable member 132 disposed in contact with the edge support 131, a reflective plate 133, and an array of optical probes 134 (e.g., optical fibers). The edge support 131 rests on the rotatable member 132. The rotatable member 132 is generally of any suitable size and shape and is made of a heat-resistant material. During substrate processing, the edge support 131 supports the substrate (not shown for clarity) at a distance below the window 115. During substrate processing, the rotatable member 132 rotates between about 50 rotations per minute (rpm) and about 300 rpm to maximize substrate temperature uniformity during processing by minimizing the effects of thermal asymmetry in the chamber 100 on the substrate. The reflective plate 133 is positioned at a distance below the substrate. The optical probe 134 partially penetrates or fully penetrates the reflective plate 133 and is directed to the back side of the substrate during thermal processing. The optical probe 134 transmits the radiant energy received from the substrate to one or more detectors 137 (which may be pyrometers) for determining the substrate temperature. For clarity, only one detector 137 is shown, but multiple detectors 137 may be used, each coupled to one or more of the optical probes. The one or more detectors 137 may detect radiation emitted by the substrate or radiation transmitted through the substrate.

[0024] Each of the one or more detectors 137 may be any suitable photodetector. In one example, the detector 137 includes a filter that provides a spectral response that is sensitive to the wavelength of the absorption gap at substrate temperatures between about 100° C. and about 350° C. The specific photodetector used therein may be a silicon photodetector for temperatures below about 350° C., because the absorption gap of silicon varies from about 1,000 nm to about 1,200 nm from room temperature to temperatures of 350° C. The silicon photodetector may be insensitive to radiation having a wavelength greater than about 1,100 nm. For temperatures above about 350° C., the absorption edge may exceed the detection limit of the silicon photodetector, and thus any further increase in the absorption edge wavelength may not be easily detected. Similarly, a gallium arsenide (GaAs) photodetector may be insensitive to radiation having a wavelength greater than 860 nm.

[0025] The one or more detectors 137 are coupled to a controller 180, which includes one or more processors 184 and a memory 182. The controller 180 is configured to monitor and control the thermal processing operation using the one or more processors 184 and the memory 182.

[0026] The controller 180 generally includes one or more processors 184, memory 182, and support circuits. The one or more processors 184 may include a central processing unit (CPU) and may be one of any form of general purpose processor that may be used in an industrial environment. The memory 182 or non-transitory computer readable medium may be accessed by the one or more processors 184 and may be one or more of memories, such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, or any other form of digital storage, local or remote. Support circuits are coupled to the one or more processors 184 and may include caches, clock circuits, input / output subsystems, power supplies, and the like. The various methods disclosed herein may be implemented by one or more processors executing computer instruction code (e.g., software routines) stored in the memory 182, generally under the control of the one or more processors 184. When the computer instruction codes are executed by the one or more processors 184 , the one or more processors 184 control the chamber 100 to perform processes according to various methods.

[0027] Controller 180 may execute artificial intelligence or machine learning techniques to automatically identify and complete one or more tasks on behalf of a user, such as identifying an appropriate lookup temperature model or modifying the model as necessary.

[0028] The chamber 100 also includes a radiation source 150 disposed opposite at least one of the one or more detectors 137. The radiation source 150 is generally a pulsed radiation source, examples of which are described below.

[0029] like Figure 1As shown in , in one example, the chamber 100 optionally includes a beam splitter 141 in optical communication with radiation emitted by a pulsed radiation source 150. In operation, the beam splitter 141 directs radiation from the pulsed radiation source 150 to a sampling detector 139, which is used to detect source modulation directly from the pulsed radiation source 150. The sampling detector 139 can help compensate for any pulse-to-pulse modulation or other amplitude modulation. The beam splitter 141 typically has a low reflectivity, for example, less than or equal to about 30%, such as about 20%, to avoid excessive attenuation of radiation from the radiation source 150. In one example, the beam splitter 141 is a fiber-coupled beam splitter that is connected to the sampling detector 139 by an optical fiber. In Figure 1 , the beam splitter 141 is shown as being outside the chamber body 120; however, the beam splitter 141 may also be positioned inside the chamber 100 and not fiber-coupled to (for example) a radiation source 150 inside a processing region to detect radiation emitted from the radiation source 150.

[0030] As illustrated, the radiation source 150 is coupled to the chamber body 120. For clarity, the radiation source 150 is shown as being located outside the chamber body 120; however, it is also contemplated that the radiation source 150 may be located inside the chamber body 120. In one example, the radiation source 150 includes a plurality of mounts that are coupled to or mounted directly on the lamp assembly 110. In other examples, the radiation source 150 is located inside the lamp assembly 110, attached to the lamp assembly 110, immediately outside the lamp assembly 110, or positioned at another suitable location. The radiation source 150 generates radiation for input to the beam splitter 141. The radiation emitted by the radiation source 150 typically travels through the beam splitter 141 to an incident area of ​​a receiving surface of a substrate (not shown) positioned on a substrate support 130 in the chamber 100.

[0031] The radiation source 150 may include two pulsed lasers, a first laser 162a and a second laser 162b. In one example, the first laser 162a emits radiation pulses in a frequency band centered at a first wavelength, such as 1,030 nanometers (nm). The second laser 162b emits radiation pulses in a frequency band centered at a second wavelength, such as 1,080 nm. The two pulsed lasers 162a and 162b may generally be high-power lasers that emit at various wavelengths used for transmission high temperature measurements. Alternatively, the radiation source 150 may also include two or more light emitting diodes (LEDs), such as super luminescent diodes (SLEDs or SLDs). SLEDs are similar to lasers, but do not include front and rear mirrors. Alternatively, the radiation source 150 may include a single pulse laser (e.g., such as Figure 2B The laser 262 shown in FIG. 2 emits pulses of a first wavelength and a second wavelength.

[0032] Figure 2A is a partial schematic diagram of an RTP chamber 200 according to one example of the present disclosure. The chamber 200 is similar to the chamber 100; however, the chamber 200 includes a pulsed laser radiation source 250 and a source manifold 252. The chamber 200 generally includes a lamp assembly 110, a chamber body 120, and a substrate support assembly 130.

[0033] In one example, the source manifold 252 includes a plurality of beam guides 254 or optical fibers that are positioned to pass through the interstitial spaces between the lamps 111 in the lamp assembly 110 through the opening 290, such as Figure 2B As shown in . As discussed above, the lamps 111 positioned inside the tubes 112 form a honeycomb array 113. The honeycomb array 113 configuration allows the lamps 111 positioned inside the tubes 112 to be more tightly packed and closer together. The lamps 111 inside the tubes 112 extend perpendicularly or orthogonally to the upper surface of the water-cooled housing 114. A vertical interstitial space is formed within the honeycomb array 113 between the tubes 112. An opening 290 is drilled in the upper surface of the water-cooled housing 114 and extends vertically through the interstitial space parallel to the tubes 112 having the lamps 111 therein. In one example, the opening 290 further extends vertically through the window 115. The diameter of each of the openings 290 is greater than or equal to the diameter of each of the plurality of beam directors 254, so that the beam directors 254 can pass through the openings 290 to emit radiation to the incident surface of the substrate. In another example, each of the plurality of beam directors 254 includes a collimating end surface or lens 256. The collimating end surface or lens 256 generally directs the radiation onto an incident area of ​​the receiving surface of the substrate.

[0034] The radiation source 250 may include a single pulse laser 262. The pulse laser 262 is generally a high power laser that emits various wavelengths for transmission high temperature measurement. Alternatively, the radiation source 250 may include a single LED, such as an SLED. Alternatively, the radiation source 250 may include multiple pulse lasers (e.g., from Figure 2A Lasers 162a, 162b) emit pulses of the same wavelength.

[0035] like Figure 2A, the radiation source 250 includes a single laser 262. In one example, the single laser 262 emits radiation pulses in a frequency band centered at a single wavelength, such as 1,030 nanometers (nm) or 1,080 nm for a silicon substrate. The pulses emitted from the laser 262 are generally coupled into at least one optical fiber 251, which passes the pulses into a source manifold or beam splitter (such as a 2x4 beam splitter), which splits the pulses into a plurality of beam directors or optical fibers (254), each of which ends with one of the collimated end surfaces or lenses 256 at its remote end (from the single optical fiber 251). The at least one optical fiber 251 couples the radiation source 250 to the plurality of beam directors 254. In the example where pulses from laser 262 are split among four beam directors or fibers 254, the losses from the optics total about 60%, so each fiber outputs pulses within the corresponding wavelength band of laser 262 that are about 10% of the total nominal output of the laser.

[0036] The chamber 200 also includes one or more optical probes 134 aligned with one or more beam guides or optical fibers 254 to detect radiation transmitted from the radiation source 250. The chamber 200 also includes one or more detectors 137 optically coupled to the radiation source 250 and disposed opposite the radiation source across the process plane, which are generally any suitable detectors for measuring radiation as a function of direction or wavelength. In addition to the one or more detectors 137, or alternatively, in some examples, the chamber 200 includes an Indium Gallium Arsenide (InGaAs) spectrometer or an InGaAs linear array with a Near Infrared (NIR) transmission grating for detecting power as a function of wavelength at higher powers (e.g., powers above about 1100 nm).

[0037] Other examples of radiation sources 150 and 250 include, but are not limited to, any solid-state pulse source that emits radiation pulses at various frequencies, chopped incandescent sources, halogen incandescent sources, and discharge lamps.

[0038] Radiation source 150 and radiation source 250 are discussed above separately; however, the present disclosure also contemplates any combination of a variety of radiation sources, including lasers, LEDs, and broadband sources for transmission pyrometry to measure and map low to high temperatures.

[0039] Figure 3 A flow chart of a dual wavelength temperature measurement method 300 is depicted according to an example of the present disclosure. The method 300 begins at operation 310 by establishing an initial temperature of a substrate before inserting the substrate into a chamber. Establishing the initial temperature of the substrate may include taking the initial temperature of the substrate using a measurement device such as one or more of a contact measurement PT100 sensor or a thermocouple. Alternatively, establishing the initial temperature of the substrate may include assuming that the substrate is in thermal equilibrium with room temperature.

[0040] In operation 312, at least one detector (e.g., one or more detectors 137) is used to measure a first reference probe current measurement corresponding to a first wavelength emitted from a first radiation source (e.g., first laser 162a) and a second reference probe current measurement corresponding to a second wavelength emitted from a second radiation source (e.g., second laser 162b), wherein the second wavelength (e.g., 1,080 nm) is greater than the first wavelength (e.g., 1,030 nm). As will be appreciated by one skilled in the art, these reference probe current measurements can be used to correct for, for example, matrix effects, dynamic system properties, and background light. A ratio of the first reference probe current measurement to the second probe current measurement (i.e., a first reference ratio) is calculated.

[0041] In operation 314, a substrate is placed into a chamber (e.g., chamber 100) at a position on a substrate support (e.g., substrate support 130) between first and second radiation sources and one or more detectors (e.g., one or more detectors 137). A third reference probe current measurement corresponding to a first wavelength emitted from the first radiation source through the substrate and a fourth probe current measurement corresponding to a second wavelength emitted from the second radiation source through the substrate are measured. The substrate support (e.g., substrate support 130) may then be actuated to rotate the substrate. The first and second wavelengths are transmitted from at least one radiation source (e.g., first and second radiation sources) and received by the detector (e.g., one or more detectors 137) with an on / off duty cycle synchronized with the rotation of the substrate.

[0042] Alternatively, the substrate may be a patterned substrate that is placed on a substrate support and rotated. For a patterned substrate, complete rotation data is required to establish the reference ratio and the ratio of the probe current measurement. When the substrate rotates, the probe current measurement values ​​from one or more discrete wavelengths (e.g., first and second wavelengths) emitted through the patterned substrate are measured and classified as active signals or background signals. The active signal is the probe current measurement value emitted through at least one patterned portion of the substrate, while the background signal is the probe current measurement value emitted through at least one unpatterned portion of the patterned substrate. The reference probe current measurement values ​​of one or more discrete wavelengths (e.g., first and second wavelengths) are calculated by subtracting the average value of at least one complete rotation of the background signal from the average value of at least one complete rotation of the active signal.

[0043] In operation 316, a ratio of the third reference probe current measurement to the fourth reference probe current measurement (i.e., a second reference ratio) is calculated. The second reference ratio is then normalized to the first reference ratio and the initial temperature of the substrate, i.e., corrected for, for example, matrix effects, dynamic system properties, and background light.

[0044] In operation 318, a model is constructed using the normalized second reference ratio and the initial temperature measurement to determine an appropriate temperature lookup table. The substrate is heated by a heat source (e.g., by lamp 111) and the substrate temperature is determined up to a temperature threshold (preferably about 80°C) using the ratio of the probe current measurement at the first wavelength to the probe current measurement at the second wavelength and the initial temperature measurement as inputs to a selected temperature lookup table. The substrate support may be actuated to rotate the substrate with the same on / off duty cycle used in operation 314.

[0045] In operation 320, the temperature lookup table model from operation 318 is used, with only the received probe current measurements corresponding to the second wavelength as input to determine the substrate temperature above 80°C. This model allows the temperature of the substrate to be monitored during substrate processing using only one wavelength, preferably the longest wavelength of the one or more discrete wavelengths used (e.g., 1,020 nm to 1,090 nm). Using only one wavelength eliminates the need to continuously switch between different wavelengths and simplifies the temperature measurement of the substrate during processing, which ultimately reduces cost. This model is also not limited to silicon substrates and can be tailored for other semiconductor substrates such as gallium arsenide (GaAs) or gallium nitride (GaN).

[0046] Figure 4 A flow chart of a single wavelength temperature measurement method 400 is depicted according to an example of the present disclosure. The method 400 begins at operation 410 by establishing an initial temperature of a substrate before inserting the substrate into a chamber (e.g., chamber 200). The initial temperature may be established by taking measurements using a temperature measurement device such as one or more of a contact measurement PT100 sensor or a thermocouple. Alternatively, the initial temperature may be established by assuming that the substrate is in thermal equilibrium with room temperature.

[0047] At operation 412, before inserting the substrate into a chamber (e.g., chamber 200), a first reference probe current measurement corresponding to a single wavelength (e.g., 1,020 nm to 1,090 nm for a silicon substrate) emitted from a single radiation source (e.g., laser 162) is measured using at least one detector (e.g., one or more detectors 137).

[0048] In operation 414, a substrate is placed into a chamber (e.g., chamber 200) at a position on a substrate support (e.g., substrate support 130) between a single radiation source (e.g., laser 162) and one or more detectors (e.g., one or more detectors 137). A second reference probe current measurement corresponding to a single wavelength emitted from the single radiation source through the substrate is measured.

[0049] In operation 416, the doping of the substrate is determined using the second reference probe current measurement and the initial temperature measurement from 410. With the initial temperature and the known intensity of radiation passing through the substrate by the one or more detectors 137, the emissivity of the substrate can be calculated. When the emissivity is determined, it is possible to determine the dopant concentration in the substrate. Calculating the emissivity and determining the doping of the substrate reduces the need for the operator to have an emissivity value for the substrate known or assumed to be uniform, resulting in a more accurate emissivity value, thereby improving performance.

[0050] In operation 418 , a model for temperature measurement based on a temperature lookup table is constructed using the doping of the substrate as an input to determine the temperature of the substrate based on probe current measurements at a single wavelength received by one or more detectors.

[0051] In operation 420, the substrate is heated (e.g., by lamp 111), and the single radiation source periodically emits a single wavelength. The one or more detectors (e.g., one or more detectors 137) receive probe current measurements at the single wavelength. The model then uses the probe current measurements to determine the current substrate temperature. This model allows monitoring of substrate temperature using only one wavelength during substrate processing.

[0052] Figure 5 A flow chart is provided for illustrating exemplary operations performed by a system controller (eg, controller 180) according to one or more aspects of the present disclosure. Figure 1 The RTP chamber 100 is described in the context of Figure 5 For example, while executing instructions from memory 182 at one or more processors 184 of controller 180 , controller 180 may perform one or more of operations 510 - 524 in accordance with one or more aspects of the present disclosure.

[0053] In operation 510 , the controller 180 may activate an initial temperature measurement device, such as a contact measurement PT100 or a thermocouple, and the radiation source 150 .

[0054] In operation 512, in response to the start-up, the controller 180 may receive an initial substrate temperature measurement from an initial temperature measurement device and may receive a first initial probe current measurement from one or more detectors 137 for a first wavelength of the first laser 162a and a second initial probe current measurement from one or more detectors 137 for a second wavelength of the second laser 162b.

[0055] In operation 514, the controller 180 may identify a normalized ratio between the first initial probe current measurement, the second initial probe current measurement, and the initial substrate temperature. The controller 180 may then identify a temperature lookup model based on the normalized ratio.

[0056] In operation 516 , in response to identifying the normalized ratio and the appropriate lookup temperature model, the controller 180 may then initiate thermal processing by switching the lamp 111 to an ON state.

[0057] In operation 518, the controller 180 may then cause the first laser 162a and the second laser 162b to emit radiation pulses through the substrate at their respective wavelengths. The one or more detectors 137 receive the radiation pulses and determine the probe current based on the received radiation pulses. The controller 180 determines the temperature of the substrate using a normalized ratio based on the received probe current until the substrate temperature measurement is above a temperature threshold. In response, the controller 180 may deactivate the first laser 162a and further determine the substrate temperature using a temperature lookup model with only the received probe current data from the second laser 162b as input.

[0058] In operation 520, the controller 180 may then cause the lamp 111 to switch to an OFF state. In response to the lamp 111 switching to the OFF state, the controller 180 may cause one or more detectors 137 to receive true temperature measurements from the substrate while causing one or more detectors to continue to receive probe current data for use as input to the selected temperature lookup model in order to continue to determine the temperature of the substrate as a model measurement. When the lamp 111 is switched OFF, thermal noise is effectively removed. Similar to operation 510, by continuing to monitor the substrate temperature using the ratio of the received probe current to the initial temperature, the recorded temperature may be considered the "true" temperature of the substrate.

[0059] In operation 522 , in response to receiving the actual temperature measurement value and the model measurement value, the controller 180 may calculate an error ratio between the model measurement value and the actual temperature measurement value.

[0060] In operation 524 , the controller 180 may modify the lookup temperature model based on the error ratio.

[0061] Figure 6 FIG. 2 is a flow chart illustrating another example of operations performed by the controller 180 according to one or more aspects of the present disclosure. Figure 6 For example, controller 180 may perform one or more of operations 610-624 in accordance with one or more aspects of the present disclosure while executing at one or more processors 184 of a computing device.

[0062] In operation 610 , the controller 180 may activate an initial temperature measurement device and the radiation source 250 using the laser 162 .

[0063] In operation 612 , in response to the activation, the controller 180 may receive an initial substrate temperature measurement from an initial temperature measurement device and may receive an initial probe current measurement for the wavelength emitted by the laser 162 from the one or more detectors 137 .

[0064] In response to receiving the initial probe current measurement and the initial temperature measurement, the controller 180 may identify a substrate doping of the substrate based on the initial probe current measurement and the initial substrate temperature measurement in operation 614. The controller 180 may then identify a temperature lookup model, such as in the memory 182, based on the substrate doping measurement in operation 616.

[0065] In response to identifying the lookup temperature pattern, the controller 180 may then initiate thermal processing by switching the lamp 111 to an ON state in operation 618. The controller 180 may then cause the laser to emit radiation pulses at a single wavelength through the substrate. The one or more detectors 137 receive the radiation pulses and determine the probe current based on the received radiation pulses.

[0066] In operation 620 , the controller 180 receives the probe current and determines the temperature of the substrate based on the received probe current using a temperature lookup model with the received probe current data as an input.

[0067] The controller 180 may then cause the lamp 111 to switch to the OFF state in operation 622. In response to the lamp switching to the OFF state, the controller 180 may cause the one or more detectors 137 to receive true temperature measurements from the substrate while simultaneously causing the one or more detectors to continue to receive probe current data for use as input to the selected temperature lookup model in order to continue to determine the temperature of the substrate as a model measurement.

[0068] In operation 624 , in response to receiving the actual temperature measurement and the model measurement, the controller 180 may calculate an error ratio between the model measurement and the actual temperature measurement.

[0069] In operation 626 , the controller 180 may modify the lookup temperature model based on the error ratio.

[0070] In the case of multiple radiation sources, a mix of full on / full off and amplitude modulation may be used. The pulsing of one or more of the radiation sources 150 or 250 may be synchronized with the wafer rotation to read from the same location on the substrate, or various pulsing patterns may be used to obtain readings from various locations on the substrate. In one example, the pulsing frequency is selected to enhance discrimination of radiation transmitted by a heat source.

[0071] In some examples using pulsed radiation sources, the radiation emitted from the multiple lamps may have a wavelength from about 1,020 nm to about 1,090 nm, which when detected by one or more detectors may be the thermal noise or background noise of the radiation emitted from the one or more radiation sources, especially when the emitted radiation is between 1,020 nm and 1,090 nm (which would be the case for processing silicon substrates). When the laser or other pulsed radiation source is off, the background noise is measured. When the laser is on, the background noise is subtracted from the detected radiation to obtain the true transmission signal. In order to improve the measurement accuracy of the substrate from low temperature to high temperature, the one or more detectors record radiation when the one or more radiation sources are on and when the one or more radiation sources are off. The signal obtained by the one or more detectors when the one or more radiation sources are off is subtracted from the signal obtained by the one or more detectors when the one or more radiation sources are on, and the resulting signal (i.e., temperature) is a more accurate measurement of the substrate temperature. Because the radiation from the one or more radiation sources is pulsed, background radiation can be recorded and subtracted from the measurements when the one or more radiation sources are switched on.

[0072] In another example, an integral transform technique (such as Fast Fourier Transform (FFT)) is used to reduce or eliminate background noise in the chamber to remove frequency contributions associated with the noise. The types of noise that can be eliminated include, but are not limited to, photon noise, electronic noise, or electromagnetic noise.

[0073] Benefits of the present disclosure include temperature measurement over a wide range from low to high temperatures. Once measured, the temperature is generally plotted to depict the change in temperature over time on the substrate surface, which is beneficial to the substrate manufacturing process. Benefits of the present disclosure include the use of a single wavelength for temperature measurement during processing, which reduces or eliminates the need to continuously switch between different wavelengths, resulting in lower cost and easier thermal processing. In addition, the present disclosure is not limited to silicon-based substrates and can be applied to substrates including other semiconductor materials such as gallium arsenide (GaAs) or gallium nitride (GaN).

[0074] While the foregoing is directed to examples of the present disclosure, other and further examples of the disclosure may be devised without departing from the basic scope of the disclosure, and the scope of the disclosure is determined by the following claims.

Claims

1. A method for measuring the temperature of a substrate, the method comprising: determining an initial substrate temperature prior to processing the substrate in the chamber; prior to processing the substrate, transmitting a first plurality of pulses at a first wavelength from a first radiation source through a first surface of the substrate; prior to processing the substrate, transmitting a second plurality of pulses at a second wavelength from a second radiation source through the first surface of the substrate, wherein the second wavelength is greater than the first wavelength; receiving the first plurality of pulses and the second plurality of pulses using at least one detector facing a second surface of the substrate, the second surface being opposite to the first surface, before processing the substrate; determining, prior to processing the substrate, a reference probe current ratio, wherein the reference probe current ratio is a ratio of a first initial probe current measurement corresponding to the first plurality of pulses to a second initial probe current measurement corresponding to the second plurality of pulses received by the at least one detector; constructing a model using the initial substrate temperature and the reference probe current ratio prior to processing the substrate; processing the substrate by heating the substrate with one or more heat sources; transmitting a third plurality of pulses at the first wavelength from the first radiation source and a fourth plurality of pulses at the second wavelength from the second radiation source through the first surface of the substrate while processing the substrate; receiving, using the at least one detector, one or more probe current measurements corresponding to the first wavelength and one or more probe current measurements corresponding to the second wavelength while processing the substrate; as well as The model is used to determine a transient temperature of the substrate while processing the substrate using the one or more probe current measurements corresponding to the second wavelength.

2. The method of claim 1, wherein using the model comprises: using a normalized ratio between the reference probe current ratio and the initial substrate temperature to determine the instantaneous temperature of the substrate until the instantaneous temperature reaches a predetermined temperature threshold; as well as After the instantaneous temperature of the substrate exceeds the predetermined temperature threshold, a lookup temperature model is used to further determine the instantaneous temperature exceeding the predetermined temperature threshold, wherein only the probe current measurement corresponding to the second wavelength is used as an input.

3. The method of claim 1, wherein the one or more heat sources include at least one lamp. The method of claim 1 , wherein the initial substrate temperature is measured using a thermocouple.

5. The method of claim 1, wherein the one or more detectors include at least one pyrometer.

6. The method of claim 1, further comprising: The substrate is placed onto a substrate support within the chamber and the substrate support is actuated so that the substrate rotates while the substrate is processed.

7. A method for measuring the temperature of a substrate, the method comprising: determining an initial substrate temperature prior to processing the substrate in the chamber; prior to processing the substrate, transmitting a first plurality of pulses at a single wavelength from a single radiation source through a first surface of the substrate; receiving the first plurality of pulses using at least one detector facing a second surface of the substrate, the second surface opposite the first surface, prior to processing the substrate; prior to processing the substrate in the chamber, determining initial probe current measurements corresponding to the first plurality of pulses received by the at least one detector prior to processing the substrate; constructing a model using the initial substrate temperature and the initial probe current measurements; processing the substrate by heating the substrate with one or more heat sources; transmitting a second plurality of pulses at the single wavelength from the single radiation source through the first surface of the substrate while processing the substrate; receiving the second plurality of pulses using the at least one detector while processing the substrate to produce a plurality of probe current measurements; as well as An instantaneous temperature of the substrate is determined while processing the substrate using at least one of the model and the plurality of probe current measurements.

8. The method of claim 7, wherein using the model comprises: determining a doping of the substrate using the initial substrate temperature and the initial probe current measurement; determining a lookup temperature model using the doping of the substrate; as well as The instantaneous temperature of the substrate is determined using the lookup temperature model using the plurality of probe current measurements corresponding to the single wavelength as input.

9. The method of claim 7, wherein the initial substrate temperature is measured using a thermocouple.

10. The method of claim 7, wherein the at least one detector comprises a pyrometer. The method of claim 7 , wherein the substrate is a patterned substrate.

12. The method of claim 7, further comprising: The model is used to determine the temperature measurements of the substrate during processing by inputting the plurality of probe current measurements at the single wavelength into the model.

13. The method of claim 7, further comprising: The substrate is placed onto a substrate support within the chamber and the substrate support is actuated so that the substrate rotates while the substrate is processed.

14. A processing system, comprising: Chamber; a substrate support disposed in the chamber; a plurality of heat sources disposed in the chamber; one or more radiation sources coupled to the chamber; one or more detection devices coupled to the chamber; and a controller coupled to the chamber and configured to cause the system to perform a method for measuring a temperature of a substrate disposed on the substrate support, the method comprising: prior to processing the substrate, transmitting a first plurality of pulses at a single wavelength from the one or more radiation sources through a first surface of the substrate; receiving the first plurality of pulses using the one or more detection devices facing a second surface of the substrate, the second surface opposite the first surface, prior to processing the substrate; prior to processing the substrate, determining initial probe current measurements corresponding to the first plurality of pulses received by the one or more detection devices prior to processing the substrate; constructing a model using the initial substrate temperature and the initial probe current measurements; processing the substrate by heating the substrate with the plurality of heat sources; transmitting a second plurality of pulses at the single wavelength from the single radiation source through the first surface of the substrate while processing the substrate; receiving the second plurality of pulses using the one or more detection devices to generate a plurality of probe current measurements while processing the substrate; and An instantaneous temperature of the substrate is determined while processing the substrate using at least one of the model and the plurality of probe current measurements.

15. The system of claim 14, wherein said using said model comprises: determining a doping of the substrate using the initial substrate temperature and the initial probe current measurement; determining a lookup temperature model using the doping of the substrate; as well as The lookup temperature model is used to determine the instantaneous temperature of the substrate using the plurality of probe current measurements corresponding to the single wavelength as input.

16. The system of claim 15, wherein the one or more heat sources include at least one lamp.

17. The system of claim 15, wherein the substrate is a patterned substrate and comprises a patterned portion and an unpatterned portion.

18. The system of claim 17, wherein the method further comprises: transmitting the plurality of first pulses through the patterned portion and the unpatterned portion such that the initial probe current measurement includes a plurality of first active signals corresponding to the patterned portion and a plurality of first background signals corresponding to the unpatterned portion; as well as The second pulses are transmitted through the patterned portion and the unpatterned portion such that the second probe current measurements include a second active signal corresponding to the patterned portion and a second background signal corresponding to the unpatterned portion.

19. The system of claim 18, wherein the method further comprises: An average value of the plurality of first active signals and an average value of the plurality of first background signals are determined, and the average value of the plurality of first background signals is then subtracted from the average value of the plurality of first active signals to determine the initial probe current measurement value.

20. The system of claim 19, wherein the method further comprises: An average value of the second active signals and an average value of the second background signals are determined, and then the average value of the second background signals is subtracted from the average value of the second active signals.

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