Synchronization between temperature measuring device and radiation source

Abstract

The method, system, device, and apparatus measure the temperature of a substrate by switching one or more radiation sources between an active state and an inactive state. When in the active state, the one or more radiation sources heat at least one portion of the substrate. When in the inactive state, the one or more radiation sources generate substantially no radiation or a negligible amount of radiation. The temperature measurement device is synchronized with the switching between the active state and the inactive state, and the temperature measurement device substantially measures the temperature of at least one portion of the substrate only when the one or more radiation sources are in the inactive state.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 064,968, filed August 13, 2020, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The present invention relates to the handling and / or processing of workpieces such as semiconductor wafers and substrates. [Background technology]

[0003] In semiconductor device manufacturing processes, various processing steps are performed in which a wafer is heated to a desired temperature on a timescale of a few seconds or less by a heat source, which may be in the form of a high intensity radiation source such as an LED, laser, or lamp. In some cases, the wafer undergoes thermal processing to perform various manufacturing steps including, for example, dopant activation, thermal oxidation, metal reflow, and chemical vapor deposition. In other cases, the wafer may be heated as a by-product of certain processing operations, such as heating of the wafer by exposure to a plasma. The temperature of the wafer is monitored / measured, for example, using a radiation thermometer, to track the temperature profile of the wafer during processing. Summary of the Invention

[0004] The present invention is a method, apparatus, device and system for measuring / monitoring parameters of a workpiece / substrate, including the temperature of the workpiece / substrate and the reflectivity and / or emissivity of the workpiece / substrate.

[0005] In a particular embodiment, the apparatus includes a device and / or one or more sensors configured to measure temperature via measurement of thermal radiation emitted by a substrate or workpiece heated by a plurality of radiation sources. The device and / or sensor operate in synchronization with the radiation sources, which switch between a first ("active") state in which the radiation sources irradiate the substrate so as to heat it, and a second ("inactive") state in which they emit no radiation or emit a negligible amount of radiation such that radiation emitted by the radiation sources is not detected by the device (and / or sensor) or is insufficient to measurably affect measurements performed by the device (and / or sensor). In a preferred embodiment, the synchronization of the device (and / or sensor) with the radiation sources is such that the device and / or sensor measures temperature (or thermal radiation) only when the radiation sources are in the inactive state, and more preferably initiates / starts performing such temperature / thermal radiation measurements only when the radiation sources are switched from the active state to the inactive state, and stops performing temperature / thermal radiation measurements of the substrate / workpiece only when the radiation sources are switched from the inactive state to the active state. In a particularly preferred embodiment, the device and / or sensor starts measuring the substrate temperature / thermal radiation only when the radiation source is switched to a deactivated state, and the radiation source is switched back to an activated state only when the device and / or sensor stops measuring the substrate temperature / thermal radiation.

[0006] In certain embodiments, the first sensor operates in synchronization with the radiation source to monitor / measure an intensity parameter that varies as a function of the intensity of the thermal radiation emitted by the substrate during periods when the radiation source is in an inactive state, and to generate an electrical signal indicative of temperature corresponding to the intensity parameter. In some embodiments, the synchronization is provided by a controller that controls the switching of the radiation source between two states. In other embodiments, the synchronization is provided by a second sensor arranged to measure / monitor an intensity parameter that varies as a function of the intensity of the radiation emitted by the radiation source, and to generate an electrical signal indicative of intensity corresponding to the intensity parameter. In an embodiment, a drop in the signal indicative of intensity is used to synchronize the switching of the radiation source between two states and the measurement performed by the first sensor.

[0007] In further embodiments, the device (and / or sensor) additionally measures radiation during periods when the radiation source is switched to an active state to capture radiation reflected by the substrate in response to being illuminated by the radiation source. In such embodiments, the captured reflected radiation may be used to measure or calculate the reflectivity and / or emissivity of the substrate.

[0008] In accordance with the teachings of one embodiment of the present invention, a method for measuring a temperature of a substrate is provided. The method includes switching one or more radiation sources between an active state, in which the one or more radiation sources heat at least one portion of the substrate, and an inactive state, in which the one or more radiation sources generate substantially no radiation or a negligible amount of radiation, and measuring a temperature using a temperature measurement device synchronized with the switching between the active and inactive states, wherein the temperature measurement device substantially measures a temperature of the at least one portion of the substrate only when the one or more radiation sources are in the inactive state.

[0009] Optionally, the one or more radiation sources irradiate the substrate during the active state so as to heat the substrate.

[0010] Optionally, the one or more radiation sources include a plurality of light emitting diodes or a plurality of laser radiation sources arranged to irradiate the substrate.

[0011] Optionally, the one or more radiation sources include a plasma configured to bombard the substrate with charged particles while active.

[0012] Optionally, the temperature measurement device is synchronized to switching between the active and inactive states via a synchronization signal corresponding to at least one of the inactive state, a transition from the active state to the inactive state, or a transition from the inactive state to the active state.

[0013] Optionally, the synchronization signal is provided by an intensity sensor arranged to sense radiation emitted by one or more radiation sources.

[0014] Optionally, the synchronization signal is provided by a controller associated with the one or more radiation sources that controls switching of said one or more radiation sources between active and inactive states.

[0015] Optionally, the temperature measurement device includes a sensor that senses radiation emitted by the radiation source and is synchronized to switching of one or more radiation sources between active and inactive states by identifying a drop in the emitted radiation corresponding to the start of the inactive state.

[0016] Optionally, the temperature measurement device begins performing temperature measurements at or after the one or more radiation sources are switched from an active state to an inactive state, and the temperature measurement device is synchronized to switching between the active and inactive states such that the temperature measurement device stops performing temperature measurements on the substrate at or before the one or more radiation sources are switched from an inactive state to an active state.

[0017] Optionally, the temperature measurement device is synchronized to switch between active and inactive states such that when the temperature measurement device stops taking temperature measurements, the one or more radiation sources switch from an inactive state to an active state.

[0018] Optionally, the active state is associated with at least one irradiation time interval, each of the at least one irradiation time interval being a time interval during which the one or more radiation sources emit radiation at a power high enough to heat the substrate, or at an average power taken over an entire time interval, and the inactive state is associated with at least one measurement time interval, each of the at least one irradiation time interval being a time interval during which the one or more radiation sources do not emit radiation, or emit radiation at a power low enough that it is negligible to the temperature measurement device.

[0019] There is further provided a system for measuring a temperature of a substrate according to an embodiment of the present teachings, the system including one or more radiation sources disposed in association with the substrate, the one or more radiation sources switching between an active state in which the one or more radiation sources heat at least one portion of the substrate and an inactive state in which the one or more radiation sources generate substantially no radiation or a negligible amount of radiation, a controller including at least one processor and configured to switch the one or more radiation sources between the active and inactive states, and a temperature measurement device configured to measure a temperature of the at least one portion of the substrate, the temperature measurement device and the switching between the active and inactive states being synchronized with each other such that the temperature measurement device substantially measures a temperature of the at least one portion of the substrate only when the one or more radiation sources are in the inactive state.

[0020] Optionally, at least one temperature measurement device is synchronized to switching between active and inactive states of one or more radiation sources via a synchronization signal corresponding to at least one of inactivity, a transition from an active state to an inactive state, or a transition from an inactive state to an active state.

[0021] Optionally, a synchronization signal is provided by the controller to the at least one temperature measurement device.

[0022] Optionally, the system further includes at least one intensity sensor disposed to sense radiation emitted by the one or more radiation sources.

[0023] Optionally, the at least one intensity sensor provides a synchronization signal to the at least one temperature measuring device.

[0024] Optionally, at least one temperature measurement device is synchronized to the switching of the one or more radiation sources by measuring radiation and identifying a drop in the measured radiation that corresponds to the onset of an inactive state.

[0025] Optionally, the one or more radiation sources irradiate the substrate during the active state so as to heat the substrate.

[0026] Optionally, the one or more radiation sources include multiple light emitting diodes or multiple laser radiation sources.

[0027] Optionally, the one or more radiation sources include a plasma configured to bombard the substrate with charged particles while in an active state.

[0028] Optionally, the temperature measurement device is synchronized with switching between the active and inactive states such that the temperature measurement device begins performing temperature measurements at or after the one or more radiation sources are switched from an active state to an inactive state, and the temperature measurement device stops performing temperature measurements on the substrate at or before the one or more radiation sources are switched from an inactive state to an active state.

[0029] Optionally, switching between the active and inactive states is synchronized with the temperature measurement device such that when the temperature measurement device stops taking temperature measurements, the controller switches the one or more radiation sources from the inactive state to the active state.

[0030] Optionally, the active state is associated with at least one irradiation time interval, each of the at least one irradiation time interval being a time interval during which one or more radiation sources emit radiation at a power high enough to heat the substrate, or at an average power taken over the entire time interval, and the inactive state is associated with at least one measurement time interval, each of the at least one irradiation time interval being a time interval during which one or more radiation sources do not emit radiation, or emit radiation at a power low enough that it is negligible to the temperature measurement device.

[0031] According to one embodiment of the present teachings, a method is provided, comprising: The method includes switching between an active state in which one or more radiation sources heat the substrate and an inactive state in which the one or more radiation sources generate substantially no radiation or a negligible amount of radiation, and measuring thermal radiation emitted by the substrate using an apparatus synchronized with the switching between the active and inactive states, the apparatus measuring thermal radiation substantially emitted by the substrate only when the one or more radiation sources are in the inactive state.

[0032] Optionally, the method includes calculating a temperature of the substrate based on the measured thermal radiation.

[0033] Optionally, the device is synchronized with switching between the active and inactive states such that the device begins performing thermal radiation measurements at or after the one or more radiation sources are switched from the active state to the inactive state, and the device stops performing thermal radiation measurements at or before the one or more radiation sources are switched from the inactive to the active state.

[0034] Optionally, the temperature measurement device is synchronized to switch between active and inactive states such that when the temperature measurement device stops taking temperature measurements, the one or more radiation sources switch from an inactive state to an active state.

[0035] According to one embodiment of the present teachings, there is provided a method for measuring a temperature of a substrate irradiated periodically by a plurality of radiation sources, the radiation sources being switchable between an active state in which the radiation sources irradiate the substrate to heat at least a portion of the substrate and an inactive state in which the radiation sources emit substantially no radiation or a negligible amount of radiation, the method comprising: performing temperature measurements of at least a portion of the substrate during a time period in which the radiation sources are in the inactive state according to a synchronization signal received by a temperature measurement device, the synchronization signal indicating at least one of: i) a time period in which the radiation sources are in the active state, ii) a time period in which the radiation sources are in the inactive state, iii) a transition of the radiation sources from the active state to the inactive state, or iv) a transition of the radiation sources from the inactive state to the active state, the temperature measurement device beginning to perform the temperature measurements at or after one or more of the radiation sources are switched from the active state to the inactive state, and the temperature measurement device ceasing to perform the temperature measurements of the substrate at or before one or more of the radiation sources are switched from the inactive state to the active state.

[0036] Optionally, the method further comprises terminating temperature measurement by the temperature measuring device during the period when the radiation source is active.

[0037] Optionally, the temperature measurement apparatus includes at least one sensor for sensing thermal radiation emitted by the substrate and generating a temperature indicative signal in response to the sensed radiation, and the method further includes decoupling the signal amplification electronics from the at least one sensor before or when the radiation source is switched from an inactive state to an active state.

[0038] Optionally, a synchronization signal is provided to the temperature measurement device by a controller that switches the radiation source between active and inactive states.

[0039] Optionally, the synchronization signal is provided by an intensity sensor arranged to sense radiation emitted by the radiation source.

[0040] According to one embodiment of the present teachings, there is provided a temperature measurement device for measuring a temperature of a substrate irradiated periodically by a plurality of radiation sources, the radiation sources being switchable between an active state in which the radiation sources irradiate the substrate to heat at least a portion of the substrate and an inactive state in which the radiation sources emit substantially no radiation or a negligible amount of radiation, the temperature measurement device being a sensor for sensing thermal radiation emitted by the substrate and generating a temperature indicative signal in response to the sensed thermal radiation during a period in which the radiation sources are in the inactive state according to a synchronization signal received by the temperature measurement device, the synchronization signal indicating at least one of: i) a period in which the radiation sources are in the active state, ii) a period in which the radiation sources are in the inactive state, iii) a transition of the radiation sources from the active state to the inactive state, or iv) a transition of the radiation sources from the inactive state to the active state, the temperature measurement device beginning to perform temperature measurements at or after one or more of the radiation sources are switched from the active state to the inactive state, and the temperature measurement device ceasing to perform temperature measurements of the substrate at or before one or more of the radiation sources are switched from the inactive state to the active state.

[0041] According to one embodiment of the present teachings, there is provided a temperature measurement apparatus for measuring a temperature of a substrate cyclically irradiated by a plurality of radiation sources configured to switch between an active state in which the radiation sources irradiate the substrate to heat it and an inactive state in which the radiation sources emit substantially no radiation or a negligible amount of radiation. The temperature measurement apparatus includes a sensor for sensing thermal radiation emitted by the substrate and generating a temperature indicative signal in response to the sensed thermal radiation, the sensor being synchronized with switching of the radiation sources between the active and inactive states such that the sensor generates the temperature indicative signal only during periods in which the radiation sources are in the inactive states.

[0042] According to one embodiment of the present teachings, there is provided an apparatus adapted to operate with or as part of a thermal processing system for processing a substrate, the thermal processing system comprising a plurality of switchable radiation sources configured to switch between an active state in which the radiation sources irradiate the substrate to heat at least a portion of the substrate and an inactive state in which the radiation sources emit substantially no radiation or a negligible amount of radiation. The apparatus includes a first sensor for sensing thermal radiation emitted from the substrate and generating a temperature indicative signal in response to the sensed thermal radiation, a second sensor for sensing radiation emitted from the radiation sources and generating a synchronization signal corresponding to the inactive state, an amplifier circuit, and a controllable switch associated with the first sensor and the amplifier circuit and configured to be switched based on the synchronization signal between an open position in which the amplifier circuit is decoupled from the first sensor and a closed position in which the amplifier circuit is placed in signal communication with the first sensor only during periods when the radiation source is in the inactive mode.

[0043] According to one embodiment of the present teachings, there is provided an apparatus adapted to operate with or as part of a thermal processing system for processing a substrate, the thermal processing system comprising a plurality of switchable radiation sources configured to switch between an active state in which the radiation sources irradiate the substrate to heat at least a portion of the substrate and an inactive state in which the radiation sources emit substantially no radiation or a negligible amount of radiation, the apparatus including a temperature measurement device including at least one sensor for sensing thermal radiation, generating a signal corresponding to the sensed thermal radiation, detecting a decrease in the signal corresponding to a period in which the radiation sources transition from the active state to the inactive state, and generating a temperature measurement of at least a portion of the substrate based on the sensed thermal radiation and the decrease in the detected signal.

[0044] According to one embodiment of the present teachings, a method is provided, the method comprising: switching one or more radiation sources between an active state in which the one or more radiation sources irradiate the substrate so as to heat the substrate, and an inactive state in which the one or more radiation sources emit substantially no radiation or emit a negligible amount of radiation; and, by an apparatus synchronized with the switching between the active and inactive states, a first radiation measurement during an inactive state, the first radiation measurement including radiation corresponding to thermal emission by the substrate; a second radiation measurement during an active state, the second radiation measurement including radiation corresponding to thermal emission by the substrate and radiation reflected by the substrate in response to radiation emitted by one or more radiation sources; and performing a calculation of at least one of a reflectivity of the substrate or an emissivity of the substrate based on the first radiation measurement and the second radiation measurement.

[0045] Unless otherwise defined herein, all technical and / or scientific terms used herein have the same meaning as understood by those skilled in the art to which this invention belongs. Similar or equivalent methods and materials to those described herein may be used in carrying out or testing embodiments of the present invention, and exemplary methods and / or materials are described below. In case of conflict, the present patent specification, including definitions, will control. In addition, the materials, methods, and examples are merely illustrative and are not necessarily intended to be limiting. [Brief description of the drawings]

[0046] Some embodiments of the present invention are described herein, by way of example only, with reference to the accompanying drawings, in which: With particular reference to the drawings in detail, it is stressed that the particulars shown are by way of example and are for the purpose of illustrating embodiments of the invention, In this regard, the description with reference to the drawings will make apparent to those skilled in the art how to practice the embodiments of the invention.

[0047] Turning now to the drawings, like reference numerals or characters indicate corresponding or similar elements. [Figure 1] FIG. 1 is a schematic diagram of a system having a measurement device with a sensor for measuring / monitoring / tracking thermal radiation and temperature of a substrate heated by a radiation source switchable between active and inactive states and synchronized with the switching of the radiation source between active and inactive states, according to one embodiment of the invention, where synchronization is provided by a controller controlling the switching of the radiation source. [Diagram 2] FIG. 2 is a block diagram of the controller of FIG. 1. [Diagram 3] FIG. 2 is a schematic diagram of the measurement device of FIG. 1. [Figure 4] 1 is a plot showing wavelengths at which an exemplary radiation source emits radiation for heating a substrate and the wavelengths of radiation that a measurement device is sensitive to. [Diagram 5] 1 is a plot showing the wavelengths at which an exemplary narrowband radiation source emits radiation for heating a substrate and the wavelengths of radiation that a measurement device is sensitive to. [Figure 6] FIG. 6 is a close-up of the low-emission region of the plot of FIG. 5 , showing the overlap of some of the low-intensity broadband radiation emitted by the radiation source with wavelengths sensitive to the measurement device, as well as the overlap with wavelengths of thermal radiation emitted by the substrate when heated to various exemplary temperatures. [Figure 7] FIG. 13 illustrates the switching states of a radiation source between active and inactive over time, along with the trend of the temperature profile of a substrate heated by the radiation source during the active state. [Figure 8] FIG. 1 is a schematic diagram of a system having a measurement device with a sensor for measuring / monitoring the thermal radiation and temperature of a substrate heated by a switchable radiation source, synchronized with the switching of the radiation source, according to another embodiment of the present invention, in which synchronization is provided by an intensity sensor measuring the radiation intensity of the radiation source. [Figure 9] FIG. 9 is a schematic diagram of a system similar to that of FIG. 8, in which the intensity sensor is integrated as part of the measurement device. [Figure 10] FIG. 2 is a schematic diagram of a system similar to that of FIG. 1, but in which the measurement device includes an amplifier and a switch between the sensor and the amplifier, the opening and closing of the switch being synchronized with the switching of the radiation source between active and inactive states. [Figure 11] 4 is a non-limiting example of a synchronization signal that may be used to provide synchronization between a measurement device and switching of a radiation source. [Figure 12] FIG. 2 is a flow diagram illustrating a process for measuring / monitoring the temperature of a substrate according to an embodiment of the present invention. [Figure 13A] 1 is a schematic diagram of a pulse width modulated (PWM) voltage waveform that may be used by a controller of the present disclosure to control a radiation source. [Figure 13B] 1 is a schematic diagram of a pulse width modulated (PWM) voltage waveform that may be used by a controller of the present disclosure to control a radiation source. [Figure 14] FIG. 2 is a schematic diagram of a system similar to FIG. 1 in which an apparatus measures the reflectivity and / or emissivity of a substrate by measuring the thermal emission of the substrate when the radiation source is in an inactive state, and measuring the thermal emission of the substrate and the reflected radiation from the substrate when the radiation source is in an active state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] The present invention is a method, apparatus, device and system for measuring / monitoring the temperature of a workpiece / substrate.

[0049] The principles and operation of methods, devices, apparatus and systems according to the present invention may be better understood with reference to the drawings accompanying this specification.

[0050] Before describing at least one embodiment of the invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details of construction and the arrangement of components and / or methods set forth in the following description and / or illustrated in the drawings and / or examples, as the invention is capable of other embodiments or of being practiced or carried out in various ways.

[0051] Referring now to the drawings, Figures 1-3 illustrate various aspects of a workpiece processing system, generally designated (10), constructed and operable in accordance with various aspects of the present disclosure. In general terms, the workpiece processing system (hereinafter referred to as "system") (10), for example when implemented as a thermal processing system, may be deployed within or as part of a thermal processing chamber and includes equipment for providing temperature monitoring / measurement during processing of a workpiece (12). Generally, the workpiece (12) may be any thin, plate-like material substrate, such as a semiconductor wafer, a semiconductor substrate, or a glass substrate. Without loss of generality, hereinafter the workpiece will be referred to interchangeably as the substrate (12).

[0052] The system (10) generally includes one or more controllable radiation sources (14) arranged to be switchably activated to selectively heat the substrate, a controller (24) for controlling the radiation sources (14), and a measurement device (16) for measuring one or more parameters of the substrate (12) based on radiation emitted or reflected by the substrate (12) in response to irradiation and / or heating by the radiation sources (14). According to a first aspect of the present disclosure, the device (16) is configured to measure the temperature of the substrate (12) based on thermal radiation emitted by the substrate (12). In an embodiment according to this first aspect of the present disclosure, the device (16) is interchangeably referred to as a "temperature measurement device". According to a second aspect of the present disclosure, the device (16) measures radiation reflected from the substrate along with thermal radiation emitted by the substrate to enable determination of the reflectivity and / or emissivity of the substrate (12).

[0053] According to certain preferred but non-limiting embodiments, one or more radiation sources (14), a plurality of electronically controllable and switchable radiation sources (14a)-(14j), collectively referred to as radiation sources (14), which may be implemented in certain embodiments as an array of radiation sources, are deployed to irradiate the substrate (12) to heat it. Although ten radiation sources are illustrated herein for illustrative purposes, the system (10) may include fewer than ten radiation sources or more than ten radiation sources depending on the thermal processing application. In such embodiments, the radiation source (14) may also be interchangeably referred to as a "radiation source" or a "heat source." The heat source (14) is preferably configured to heat at least a portion of the substrate (12) or the entire substrate (12) to a desired temperature depending on the application, which may be, for example, 175° C. or higher, in some cases 200° C. or higher, and in other cases 300° C. or higher. When used in the context of a rapid thermal processing system, the radiation source (14) may be configured to heat the substrate (12) to even higher temperatures, including temperatures of 1000° C. or higher.

[0054] As an addendum, although the radiation source (14) is embodied as a radiation source for irradiating the substrate (12) to heat the substrate (12), other embodiments are contemplated herein in which there is not necessarily a causal relationship between the radiation generated by the radiation source (14) and the heating of the substrate (12). For example, and as discussed in subsequent portions of this disclosure, certain radiation sources may be switchably activated to heat the substrate (12) and may cause the generation of radiation (i.e., radiative emission) that is not responsible for the heating of the substrate as a side effect or by-product of the activation of the radiation source (14). Throughout much of the remainder of this disclosure, the radiation source (14) will be described in the context of being a radiation source for irradiating the substrate (12) and, where applicable, more generally as a radiation source that is generally configured to be activated to heat the substrate (12).

[0055] With the above in mind, the radiation source (14) is generally configured to switch between two states: an active state in which the radiation source (14) irradiates the substrate (12) to heat the substrate (12), and an inactive state in which the radiation source (14) does not irradiate the substrate, either by emitting no radiation or by emitting a negligible amount of radiation during the time the radiation source (14) is in the inactive state. In certain non-limiting embodiments, the intensity (i.e., power) emitted by the radiation source (14) may be varied between a minimum intensity / power value and a maximum intensity / power, thereby allowing for controllable variation in the desired temperature of the substrate (12), in combination with the amount of time between which the radiation source (14) emits radiation at the minimum and maximum intensity. The minimum intensity / power value may be, for example, 0 Watts / cm. 2 and the maximum intensity / power value can be, for example, 20 watts / cm 2 These minimum and maximum values ​​may vary depending on the application.

[0056] In the context of this document, the term "active state" is used interchangeably with the terms "activated state", "active" and "activated" and generally refers to a state in which the radiation source (14) heats the substrate (12). In a particularly preferred but non-limiting embodiment in which the radiation source (14) is a radiation source, the active state refers to a state in which the radiation source irradiates the substrate (12) by emitting radiation high enough to heat the substrate for a predetermined period of time. In such an embodiment, the active state corresponds to a time interval or period during which the radiation source (14) emits radiation at a power or average power (taken over that time interval / period) high enough to measurably heat the substrate (preferably according to a desired temperature profile). A time interval (i.e., a period) during which the radiation source (14) is in an active state is interchangeably referred to as an "irradiation time interval" or an "irradiation period". In the general case where the radiation source (14) does not irradiate the substrate but nevertheless heats the substrate while in the active state, the time interval during which the radiation source (14) is in the active state may be equivalently referred to as an "active state time interval" or an "active state period", as well as any of the other interchangeable terms used for "active state" in combination with the term "time intervals" or "periods".

[0057] Similarly, in the context of this document, the term "inactive state" is used interchangeably with the terms "deactivated state," "inactive," and "deactivated," and generally refers to a state in which the radiation source (14) does not irradiate the substrate (12), or, more generally, generates substantially no radiation or a negligible amount of radiation. In embodiments in which the radiation source (14) is a radiation source that irradiates the substrate (12) while in an active state, when in the inactive state, the radiation source (14) emits no radiation (i.e., turns off), emits a negligible amount of radiation (from the perspective of the device (16)), or emits a low level of radiation that remains for a short period of time immediately after being switched from an active state to a deactivated state. In such embodiments, the inactive state refers to a state in which the radiation source (14) emits zero (i.e., the radiation source (14) does not emit any radiation) or emits a negligible amount of radiation (i.e., a very low, non-zero amount of power, e.g., <<1 Watt / cm).2 A time interval during which the radiation source (14) emits radiation at a low enough power or average power (taken over that time interval / period) to emit a minimum of 100 Hz (at 100 Hz) of radiation. A time interval during which the radiation source (14) is in an inactive state is interchangeably referred to as an "measurement time interval" or "measurement period". In the general case where the radiation source (14) does not irradiate the substrate but nevertheless heats the substrate when in an active state, a time interval during which the radiation source (14) is in an inactive state may be equivalently referred to as an "inactive state time interval" or "inactive state period", as well as any of the other interchangeable terms used for "inactive state" in combination with the term "time intervals" or "periods".

[0058] A single measurement time interval corresponds to a period between a first time interval and a second time interval, the first time example being an example of a time during which the radiation source (14) assumes an inactive state, and the second time example being an example of a time during which the radiation source (14) successively assumes an active state after assuming an inactive state.

[0059] In the context of this document, the term "negligible amount of radiation" generally refers to any amount of radiation that is either not detectable by the temperature measurement device (16) or is insufficient to significantly affect temperature measurements of the substrate (12) made by the temperature measurement device (16).

[0060] The controller (24) is electrically associated with the radiation source (14) and configured to operate the radiation source (14) on and off to control the radiation source (14) to switch between the active and inactive states at an appropriate switching rate. In certain embodiments, the switching rate may be static / constant and can be pre-programmed into the controller (24). In other embodiments, the switching rate may be dynamic. The switching rate may depend on the heating rate and the desired temperature to which the substrate (12) is to be heated, which may depend on the particular thermal treatment application. The controller (24) is preferably further configured to adjust the intensity / power of the radiation emitted by the radiation source (14) when in the active state. In addition, and as discussed in more detail in subsequent portions of this disclosure, the controller (24) may employ various techniques to control the switching between the active and inactive states and the radiation intensity output of the radiation source (14). In a preferred but non-limiting embodiment, the controller (24) employs pulse width modulation (PWM) to control the switching and radiation intensity output of the radiation source (14).

[0061] FIG. 2 is a schematic block diagram of the controller (24) and shows a processor (26), which may be one or more computer processors (e.g., microprocessors, microcontrollers, signal processors, etc.) coupled to a computer storage medium, represented generally as memory (28). Such a processor may include or be in communication with a computer readable medium (e.g., memory (28)) that stores computer program code or instruction sets that, when executed by the processor, cause the processor to perform operations. Types of computer readable media include, but are not limited to, electronic, optical, magnetic, or other storage or transmission devices that may provide computer readable instructions to the processor. Memory (28) may be any type of memory for storing data and information, and may also store computer program code or instruction sets for execution by the processor (26).

[0062] In certain embodiments, each individual radiation source (14a)-(14j) is independently controllable by the controller (24), such that the controller (24) can selectively turn each radiation source on and off independently. In other embodiments, the radiation sources (14) are turned on and off collectively by the controller (24), such that when the controller (24) issues an "on" control command, all of the radiation sources (14) are switched on simultaneously, and when the controller (24) issues an "off" control command, all of the radiation sources (14) are switched off simultaneously.

[0063] The temperature measurement device (16) (also referred to as a "temperature measurement device" or simply "device") is arranged to measure the temperature of a portion of the substrate (12), which may be a portion of the substrate (12) or the entire substrate (12). In certain embodiments, the temperature measurement device (16) is implemented as a radiation thermometer, such as a temperature probe, which may be a stand-alone component separate from the radiation source (14) and controller (24) of the system (10) or may be integrated with other components of the system (10).

[0064] In certain preferred embodiments, the radiation sources (14) are positioned relative to the substrate (12) to irradiate the substrate (12) from a wide range of angles such that the entire substrate (12) is heated. In such embodiments, the radiation sources (14) may be configured as an array of heat sources.

[0065] In a particularly preferred, but non-limiting set of embodiments, the radiation source (14) is implemented as an arrangement of multiple electronically switchable light emitting diodes (LEDs), optionally arranged in an array, or laser sources, configured to emit radiation in a particular wavelength range, preferably from a wide range of angles, to heat the substrate (12) to a desired temperature. LEDs and lasers offer several advantages over incandescent bulbs and other types of lamps in thermal processing, particularly in the precision with which LEDs and lasers can be electrically controlled. In addition, LEDs and lasers can be switched on and off quickly, allowing an LED's light output to go from zero to full power (or vice versa) in as little as a second or so.

[0066] However, it should be noted that the radiation output of an LED, laser, or other radiation source may at least partially overlap with a particularly preferred wavelength range for measuring the temperature of the substrate (12) by the temperature measuring device (16). This can be seen in the example illustrated in FIG. 4, where the temperature measuring device (16) operates at about 950 nm and the radiation source emits a peak radiation at about 870 nm, but also emits radiation up to 950 nm. Thus, when switched on, the radiation emitted by the LED / laser / radiation source may interfere with the temperature measurement of the substrate (12). Even LED and laser heat sources operating far away from the temperature probe operating wavelength band, for example near 500 nm, still emit broadband radiation that, although weaker overall, may overlap and interfere with a temperature measuring device (16) operating near a longer wavelength, for example near 950 nm. This is illustrated in Figure 5, where the radiation source (14) emits a narrowband peak radiation around 500 nm, but still emits broadband radiation (shown in a close-up in Figure 6) that is strong enough to interfere with the lower thermal signal levels emitted by the substrate (12) when heated to various exemplary temperature levels (175°C, 200°C, and 300°C in this example). Thus, if the temperature measurement is performed during the period when the radiation source (14) is active, the temperature measurement reading of the substrate (12) may be obscured.

[0067] To prevent radiation from the radiation source 14 from obscuring the temperature measurement readings of the substrate 12, the temperature measurement device 16 according to embodiments of the present disclosure is synchronized to the switching of the radiation source 14 between active and inactive states such that the temperature measurement device 16 begins making temperature measurements at the same time or a small amount of time after the radiation source 14 switches from the active state to the inactive state, and the temperature measurement device 16 stops making temperature measurements of the substrate 12 at the same time or a small amount of time before the radiation source 14 switches from the inactive state to the active state. In this manner, the only significant temperature measurements made by the temperature measurement device 16 are made during the period when the radiation source 14 is in the inactive state. It should be noted that the "small amount of time" at the beginning and / or end of the inactive state during which no temperature is measured by the device 16 is generally selected as an interval long enough to allow for any uncertainty that may exist between the synchronization signal and the exact time of the transition of the radiation source 14 to / from the inactive state. The reason for adding these small intervals at the beginning and / or end of the inactive state during which no measurements are made by the device 16 is to ensure that, even in the face of uncertainty in the exact time of the transition to / from the inactive state, the device 16 will always only make measurements when the radiation source 14 is in the inactive state. In addition, in the typical case where the device 16 requires a certain minimum time to complete a temperature measurement, a tolerance may be taken to ensure that the transition of the radiation source 14 from inactive to active does not occur while the device 16 is in the middle of such a temperature measurement (so that in practice the device 16 may only be able to start a temperature measurement if there is enough time to complete this measurement before the next transition of the radiation source 14 from inactive to active).

[0068] Generally, the temperature of the substrate (12) decreases each time the radiation source is placed in an inactive state, resulting in a heating profile qualitatively similar to that shown diagrammatically in FIG. 7. In situations where tight control of the temperature profile is required and / or where the cooling of the substrate proceeds rapidly during the inactive time interval, it is generally desirable to reduce to a minimum the time interval during which the radiation source (14) is in an inactive state in order to reduce the magnitude of the temperature drop that occurs during the inactive time interval. To this end, the radiation source (14) may preferably be implemented as an LED, laser, or other radiation source with a fast response time (LEDs and lasers each typically have rise / fall times of about 1 μsec or more). The use of a radiation source with a fast response time allows the initiation of temperature measurement almost immediately after the initiation of the inactive state, and the re-establishment of the active state almost immediately after the completion of the temperature measurement. This differs from radiation sources with slower response times, such as incandescent radiation sources, whose rise / fall times are only about 0.1 seconds or more. Such slow response time sources require delaying the start of the temperature measurement until the radiation level from the slow response time source has decayed enough so that it does not interfere with the temperature measurement. Similarly, slow response time sources require some time to return to a fully active state after completing a non-active state temperature measurement. Thus, the magnitude of the temperature drop during the non-completed state time interval can be reduced by using an LED, laser, or other fast response time source.

[0069] In certain preferred but non-limiting implementations, a pulse width modulation (PWM) control method can be used to vary the average power applied to the radiation source. Figures 13A and 13B show exemplary PWM voltage waveforms used for PWM control. When a PWM control method is used, there are two possible ways to achieve synchronization between the temperature probe and the radiation source.

[0070] a) When the measurement time of the temperature probe is long compared to the PWM cycle time (T), in order to capture the temperature measurement value, it is necessary to keep the radiation source in an inactive state over one or more entire PWM cycles. This case is shown in FIG. 13A, where it is shown that after one inactive state (measurement time interval), an active state interval follows in which a higher average power is applied to the radiation source.

[0071] b) When the measurement time of the temperature probe is short compared to the PWM cycle time (T), it may be possible to fit the temperature measurement within the low voltage intervals that inherently exist during each PWM cycle (always when the PWM duty ratio is less than 100%). In this embodiment, since the inactive state occurs naturally during the PWM cycle, there is no need to insert a special inactive state measurement interval between the PWM voltage pulses. This approach is schematically illustrated in FIG. 13B. In the approach shown in this figure, not only a rapid temperature measurement time (<<T) but also a rapid switching between the active and inactive states is further required. As described above, LED and laser light sources are particularly suitable for situations where such rapid switching is required.

[0072] It will be recognized that to achieve the inactive state, it is not necessary to apply exactly zero voltage, current, power, or other suitable excitation to the radiation source. Rather, it is only necessary to apply an excitation that is low enough to ensure that the radiation source emits below the level that interferes with the temperature probe measurement.

[0073] The active time intervals and the measurement time intervals are now discussed in more detail. For clarity of illustration, the time intervals are described in the non-limiting context of the radiation source (14) being the radiation source, whereby the active time intervals are referred to as the irradiation time intervals. As is apparent, the irradiation time intervals and the measurement time intervals can each include multiple intervals. Typically, the irradiation time intervals and the measurement time intervals alternate, corresponding to switching of the radiation source (14) between the active and inactive states, such that the radiation source (14) goes through successive periods of active and inactive states, with interleaving between the irradiation time intervals and the measurement time intervals. FIG. 7 shows an example of the change in the state of the radiation source (14) over time as the radiation source (14) is cycled between the active and inactive states, along with the trend of the temperature profile of the substrate (12) resulting from the switching. 7, the temperature of the substrate (12) increases during periods when the radiation source (14) is active (i.e., the substrate (12) "heats up") and decreases during periods when the radiation source (14) is inactive (i.e., the substrate (12) "cools down"). In the illustrated example, the temperature of the substrate (12) increases as a non-linear function of time during each irradiation time interval.

[0074] Each of the irradiation time intervals is sufficiently long to allow sufficient time for the substrate (12) to be heated to an appropriate temperature. Irradiation time intervals in the range of 0.25 to 10 seconds have been found to be particularly effective for heating semiconductor wafers, although the length of the intervals may vary based on the particular heat processing application. In addition, each of the measurement time intervals is preferably shorter than the irradiation time intervals, and more preferably is a sufficiently short time interval that is compatible with synchronization with the switching times of the radiation source (14) such that the temperature of the substrate (12) may be measured (by the temperature measurement device (16)) with minimal impact on the time-dependent temperature profile. Measurement time intervals in the range of 0.01 to 0.1 seconds have been found to be particularly effective for measuring the temperature of semiconductor wafers that are heated at intervals of 0.25 to 10 seconds, although again the length of the measurement time intervals may vary based on the particular processing application.

[0075] In certain preferred embodiments, the device (16) continuously or nearly continuously measures the temperature (and / or thermal radiation) emitted by the substrate (12) for the entire duration of the measurement time interval.

[0076] As an aside, it should be noted that the exposure time intervals do not necessarily have to be of equal length. Similarly, the measurement time intervals do not necessarily have to be of equal length. For example, the exposure time intervals may be continuously increased or decreased during the thermal processing of the substrate, and the measurement time intervals may remain constant or may vary, for example, based on the length of each preceding exposure time interval.

[0077] FIG. 3 shows a schematic diagram of a temperature measurement device (16) according to certain embodiments of the present disclosure. In the illustrated embodiment, the temperature measurement device (16) comprises a sensor (20) coupled to a processor (18). The processor (18) can be one or more computer processors (e.g., microprocessors, microcontrollers, signal processors, etc.). The sensor (20) is configured to detect / sense / measure radiation (thermal radiation, radiation intensity) emitted by the substrate (12) and generate an electrical signal indicative of temperature in response to the sensed thermal radiation. The sensor (20) is preferably sensitive to radiation in a particular wavelength range selected to provide high sensitivity to changes in temperature of the substrate (12) within an expected range of desired processing temperatures to which the substrate (12) will be heated by the radiation source (14). In one non-limiting example, the sensor (20) is sensitive to radiation having a wavelength at or near 1000 nm. The sensor (20) can be two or more sensors, for example, an array of sensors. The sensor (20) can measure the temperature of the substrate (12) based on the relationship between irradiance and temperature given by the Stefan-Boltzmann law, the Planck function, or using a look-up table (which may be stored in a memory associated with the processor (18)).

[0078] In the illustrated embodiment, the temperature measurement device (16) further comprises optics (23), represented diagrammatically by a lens (23) (which may be an assembly of refractive or reflective lenses), for directing thermal radiation from the scene towards the sensor (20). Alternatively, the optics (23) may be implemented as an optical fiber(s) (e.g., a fiber optic bundle) or as a light pipe. The optics (23) are arranged to define a field of view corresponding to the area where the thermal radiation reaches. When the device (16) is deployed to measure the temperature / thermal radiation of the substrate (12), the device (16) is positioned such that the portion of the substrate (12) to be measured is in the field of view of the scene / area defined by the optics (23). Depending on the deployment configuration of the device (16) relative to the substrate (12), a "portion of the substrate" may comprise one or more portions of the substrate (12) or may comprise the entire substrate (12).

[0079] In certain embodiments, the processor (18), sensor (20), and optical element (23) are held within a single casing or mechanical body.

[0080] As an added bonus, the thermal radiation emitted by substrate 12 is generally weak, and thus sensor 20 may generate a proportionally weak temperature-indicative signal in response to sensing the thermal radiation that requires some amplification by an amplifier circuit. Thus, although not shown in the drawings, the output of sensor 20 is preferably coupled to an amplifier circuit (e.g., a preamplifier) ​​that amplifies the signal generated by sensor 20.

[0081] Synchronization between the switching of the temperature measuring device (16) and the radiation source (14) can be provided in a variety of ways. According to a set of non-limiting embodiments illustrated in FIG. 1, the controller (24) is electrically associated with (i.e., electrically coupled to) the temperature measuring device (16) and provides a synchronization signal to the temperature measuring device (16) corresponding to the irradiation time interval and / or the measurement time interval. As discussed, the synchronization signal can correspond to an inactive state and / or a transition from an active state to an inactive state and / or a transition from an inactive state to an active state. Because the controller (24) controls the switching rate of the radiation source (14), the controller (24) can also provide timing information, for example in the form of a synchronization signal, to the temperature measuring device (16) so that the temperature measuring device (16) measures the temperature of the substrate (12) only during a period corresponding to the measurement time interval. The processor (18) receives the synchronization signal and controls the timing of the sensor (20) so that the sensor (20) measures thermal radiation only during the measurement time interval. In another embodiment, the sensor (20) continuously measures the thermal radiation intensity and the processor (18) controls a switch that switchably couples the sensor (20) to the amplifier circuit to close the switch only during the measurement time interval, such that the output of the sensor (20) is in signal communication with the amplifier circuit only during the measurement time interval and not during the irradiation time interval. Variations on this embodiment are discussed later in this disclosure with reference to FIG.

[0082] In another set of non-limiting embodiments, the sensor is sensitive to radiation emitted by both the radiation source (14) and the substrate (12) and continuously senses / measures the thermal radiation intensity. In such embodiments, the processor (18) can be programmed to process the signal generated by the sensor (20) to identify a sudden drop in the signal indicative of a decrease in the measured radiation intensity. Such a drop typically corresponds to a period of time when the radiation source (14) transitions to an inactive state. Thus, the processor (18) may generate, output, and / or store or write to storage (e.g., to a computer memory linked to the processor (18)) only the segment(s) of the signal measured after detection of a sudden signal drop (corresponding to the measurement time interval, i.e., when the radiation source (14) is in an inactive state), such that only temperature measurements during the measurement time interval are output by the temperature measurement device (16). The processor (18) may similarly be programmed to stop recording measurement data when a sudden signal increase is detected, corresponding to a transition of the radiation source to an active state. Thus, the device of the present invention generates temperature measurements of the substrate (12) based on the detection of the sensed radiation and sudden drops and increases in the intensity of this sensed radiation. Alternatively, the processor (18) may identify an inactive state (where data should be recorded) whenever the sensed radiation signal falls below a certain threshold signal level, rather than based on changes in the measured signal (sudden increases and decreases).

[0083] 8 and 9, a system and device are illustrated in which synchronization is provided between the temperature measuring device (16) and the switching of the radiation source (14) according to a further embodiment of the present disclosure in which an additional sensor is employed to sense the radiation emitted by the radiation source (14). Looking first at FIG. 8, an intensity sensor (30) (which may be more than one intensity sensor) is deployed to sense the radiation emitted by the radiation source (14) and is electrically associated with the temperature measuring device (16). The intensity sensor is sensitive to a specific range of wavelengths of radiation emitted by the radiation source (14), and the sensor (20) is sensitive to a specific range of wavelengths of radiation emitted by the substrate (12) when heated by the radiation source (14). Although not illustrated, the intensity sensor (30) may be associated with an optical element to direct radiation from the scene (which in this case comprises the radiation source (14)) towards the sensor (30). Alternatively, the sensor (30) may be associated with dedicated optics that direct radiation from the radiation source (14) towards the sensor (30).

[0084] The intensity sensor 30 generates the synchronization signal based on detecting / sensing radiation in the relevant wavelength range, specifically radiation emitted by the radiation source 14. In certain non-limiting embodiments, the intensity sensor 30 generates the synchronization signal upon detecting / sensing radiation emitted by the radiation source 14. In other non-limiting embodiments, the intensity sensor 30 generates the synchronization signal when radiation in the relevant wavelength range is not detected / sensed by the intensity sensor 30.

[0085] The intensity sensor 30 provides a synchronization signal to the temperature measurement device 16 such that the temperature measurement device performs thermal radiation measurements (via the sensor 20) in accordance with the synchronization signal such that the sensor 20 measures thermal radiation (emitted by the substrate 12) only during measurement time intervals (corresponding to periods of inactivity of the radiation source 14). For example, the processor 18 of the temperature measurement device 16 can instruct the sensor 20 to perform thermal radiation measurements in response to receiving a synchronization signal from the intensity sensor 30.

[0086] Figure 9 shows an alternative configuration similar to Figure 8, but where the intensity sensor (30) is integrated as part of the temperature measurement device (16) such that both sensors (20) and (30) are deployed within a single casing or machine body. Here, similar to Figure 8, the intensity sensor (30) detects / senses / measures the radiation emitted by the radiation source (14) to determine the time when the radiation source (14) is in an inactive state (corresponding to a measurement time interval) and / or the time when the radiation source (14) is in an active state (corresponding to an irradiation time interval). Each of the sensors (20) and (30) may have separate optical elements (i.e., the sensor (20) may be associated with the optical element (23) as in Figure 3, and the sensor (30) may have separate optical elements as mentioned above with reference to Figure 8). Alternatively, sensors (20) and (30) may share an optical element (e.g., optical element (23) in FIG. 3) and may be arranged to direct radiation from both radiation source (14) and substrate (12) to sensors (20) and (30).

[0087] In the embodiment illustrated in FIG. 9, the processor (18) can receive a synchronization signal from the intensity sensor (30) and can instruct the sensor (20) to make a thermal radiation measurement based on the received synchronization signal.

[0088] Figure 10 illustrates another embodiment similar to Figure 1, except that the temperature measurement device (16) further comprises an amplifier circuit (22) for amplifying a temperature indicative signal generated by the sensor (20), and a switch (21) for selectively placing the sensor (20) in signal communication with the amplifier (22). The sensor (20) further continuously measures thermal radiation intensity and may be sensitive to radiation in a particular wavelength range emitted by the radiation source (14) in addition to being sensitive to radiation in a particular wavelength range emitted by the substrate (12) when heated by the radiation source (14). Nominally, the switch (21) may be in an open position such that the sensor (20) is decoupled (i.e., not in signal communication) from the amplifier (22). Thus, when the switch (21) is in the open position, the output signal generated by the sensor (20) in response to any radiation measurement is not amplified. When the switch (21) is in the closed position, the sensor (20) is placed in signal communication with the amplifier (22), such that an output signal generated by the sensor (20) in response to any thermal radiation measurement is amplified by the amplifier (22). Switching of the switch (21) between the open and closed positions is controlled by a control input received from the controller (24) in the form of a synchronization signal such that the amplifier (22) is decoupled from the sensor (20) at or a (small) time before the time that the radiation source (14) is switched from an inactive to an active state. In the illustrated example, the processor (18) operates as a relay to actuate the switch (21) to open or close based on the synchronization received from the controller (24). The controller (24) provides a synchronization signal corresponding to switching of the radiation source (14) between an active state and an inactive state such that when the radiation source (14) is in an active state, the switch (21) is in an open position to decouple the amplifier (22) from the sensor (20), and when the radiation source (14) is in an inactive state, the switch (21) is in a closed position.Thus, the switch is primarily closed during the measurement time interval, such that the amplifier (22) amplifies the signal generated by the sensor (20) only during the measurement time interval, and the switch (21) is primarily open during the irradiation time interval, such that the thermal radiation intensity measurements performed by the sensor (20) are not amplified and the temperature measurements performed by the device (16) are effectively interrupted / terminated.

[0089] The synchronization signal utilized in the embodiments of the present disclosure can take a variety of forms including, for example, a continuous time-varying signal over a specified duration, one or more pulse or step signals, one or more triggered signals that may include pulse / step signals, or a digital signal. In one non-limiting example, the synchronization signal is a pulse or step that has a high or low value when the radiation source (14) is in an active state and a low or high value when the radiation source (14) is in an inactive state. In such an example, the temperature measurement device (16) measures the temperature (via thermal radiation sensing by the sensor (20)) during the time intervals in which the synchronization signal has a low or high value(s) (corresponding to the inactive time intervals).

[0090] In another non-limiting example, the synchronization signal may comprise a start trigger pulse for each inactive time interval, indicating the start of the inactive time interval, and an end trigger pulse for each inactive time interval, indicating the end of the inactive time interval. In such an example, the temperature measuring device (16) starts temperature measurement upon receiving the start trigger pulse and continues temperature measurement until receiving the end trigger pulse. In another similar non-limiting example, the synchronization signal may comprise a start trigger pulse for each active time interval, indicating the start of the active time interval, and an end trigger pulse for each active time interval, indicating the end of the active time interval. In such an example, the temperature measuring device (16) starts temperature measurement upon receiving the end trigger pulse (associated with the end of an active time interval) and continues temperature measurement until receiving the start trigger pulse (associated with the start of the next active time interval). In yet another similar non-limiting example, a single trigger pulse may be used to indicate a transition of the radiation source to an inactive state, the inactive state being preprogrammed to last for a time equal to or slightly longer than the time required for the temperature probe to make one measurement. When this preprogrammed time interval ends, the radiation source automatically returns to the active state, and no trigger pulse is sent to indicate this transition.

[0091] It will be apparent that combinations of the above are also contemplated herein. For example, a synchronization signal may comprise high or low value start and end trigger pulses indicating the start and end, respectively, of an active time interval, and low or high value start and end trigger pulses indicating the start and end, respectively, of an inactive time interval.

[0092] In certain non-limiting embodiments, the synchronization signal can act as a trigger signal that triggers the temperature measuring device 16 to begin measuring the temperature of the substrate 12, while in other embodiments, the synchronization signal can act as a trigger signal that triggers the temperature measuring device 16 to stop measuring the temperature of the substrate 12. In yet other non-limiting embodiments, receipt of the synchronization signal (by the temperature measuring device 16) triggers the temperature measuring device 16 to measure the temperature of the substrate 12, while in other embodiments, the absence of receipt of the synchronization signal triggers the temperature measuring device 16 to measure the temperature of the substrate 12.

[0093] 4-10 in succession, and now FIG. 11, which shows an example of a synchronization signal that can be used to provide synchronization between the temperature measuring device (16) and the switching of the radiation source (14) between the active and inactive states. The switching of the radiation source from the active to the inactive state occurs on the rising edge of the synchronization signal, where the signal increases from a "low" signal level (designated AL) to a "high" signal level (designated AH). These instances occur at the times labeled TINAC in the figures. The measuring device (16) starts its temperature measurement simultaneously with this rising signal and completes the temperature measurement within a predefined time interval (designated TMEAS in FIG. 11), after which the radiation source (14) automatically switches back to the active state, at the time labeled TAC in the figures. Thus, the temperature measuring device (16) can only measure the temperature of the substrate (12) during the measurement time interval, i.e., the period during which the radiation source (14) is in the inactive state.

[0094] The synchronization signal may, for example, be implemented as an electrical signal, with "high" and "low" amplitude values ​​corresponding to the high and low voltages used to generate the signal, e.g., "high" being 5 volts and "low" being 0 volts.

[0095] The synchronization between the temperature measurement device (16) and the switching of the radiation source (14) between active and inactive states, particularly when implemented as an LED or laser light source, represents a significant advantage over conventional substrate temperature monitoring solutions by allowing the temperature measurement device (16) to measure temperature / thermal radiation only during periods when the radiation source (14) is in an inactive state (and preferably during the entire period when the radiation source (14) is in an inactive state). In doing so, the temperature measurement device is generally not subject to glare from much stronger heating radiation sources that would impede the ability of a temperature probe to accurately detect the typically orders of magnitude smaller thermal radiation signals emanating from the substrate (12).

[0096] In a particularly preferred synchronization implementation, synchronization allows the device (16) to start temperature measurements only at the moment the radiation source (14) is switched to the inactive state, and to switch the radiation source back to the active state only at the moment the temperature probe completes its temperature measurement. Such a synchronization implementation minimizes the duration of the inactive states, and therefore reduces uncontrolled cooling of the substrate (12) that occurs during the inactive intervals, as shown diagrammatically in FIG. 7. Furthermore, by absolutely minimizing the time intervals of inactivity, more frequent inactive measurement intervals can be inserted into the heating profile, which is particularly important when used in combination with a closed-loop temperature control scheme, where more frequent temperature measurements allow more frequent control corrections by the temperature controller, resulting in tighter and more robust temperature control.

[0097] However, it is noted that the measurement and synchronization schemes disclosed herein are also applicable to situations that do not require precise closed-loop control, such as for data recording or data collection purposes, or scenarios where an alarm or warning is issued if the measured temperature is outside of a preferred temperature range.

[0098] Attention is now directed to FIG. 12, which illustrates a flow diagram detailing a process (i.e., method) (1200) for measuring / monitoring the temperature of a substrate in accordance with an embodiment of the disclosed subject matter. Reference is further made to FIGS. 1-11. The process and sub-processes of FIG. 12 are performed by the radiation source (14), the temperature measurement device (16), and its associated components including the sensor (20) and optionally the sensor (30). Some of the processes and sub-processes of FIG. 12 are computerized processes executed by the controller (24) and / or the processor (18). The aforementioned processes and sub-processes are, for example, performed automatically, preferably in real-time. Prior to carrying out the process of FIG. 12, the substrate (12) is treated with a substrate processing system, such as a thermal processing chamber, that includes a heat and / or radiation source (e.g., radiation source (14)) that, in certain embodiments, is assumed to be arranged to irradiate the substrate (12) so as to heat the substrate, and a computerized control device (e.g., controller (24)) for switching the radiation source on / off to control switching between activated and inactivated states, and, in certain embodiments, for controlling the level of radiation intensity emitted by the radiation source when in the activated state.

[0099] The process (1200) begins with step (1202) in which the controller (24) switches the radiation source (14) to an active state such that the radiation source (14) heats the substrate (12). In the context of thermal processing, the radiation source (14) is a radiation source that, when switched to the active state in step (1202), irradiates the substrate (12), thereby heating the substrate (12) during an irradiation time interval. In step (1204), the controller (24) switches the radiation source (14) to an inactive state such that the radiation source (14) does not emit radiation, or emits a negligible amount of radiation. In the context of thermal processing, when switched to the inactive state in step (1204), the radiation source (14) no longer irradiates the substrate (12) such that the radiation source (14) does not emit radiation, or emits a negligible amount of radiation. The radiation source (12) is maintained in the inactive state during the measurement time interval. In step (1206), the substrate (12) is heated by the radiation source (14). The temperature measuring device (16) disposed adjacent to the substrate (12) begins measuring the temperature of the surrounding environment so as to measure the temperature of the substrate (12) at the beginning of the measurement time interval (which is the end of the irradiation time interval). After completion of the temperature measurement, the process (1200) then moves to step (1208), which is generally identical to step (1202), in which the controller (24) switches the radiation source (14) to an active state such that the radiation source (14) heats the substrate (12). Due to the synchronization between the temperature measuring device (16) and the switching of the radiation source (14) between the active and inactive states, the temperature measuring device stops measuring the temperature of the surrounding environment so that thermal radiation emitted by the substrate and radiation caused by (and emitted in the context of thermal processing) the radiation source (14) are not captured by the temperature measuring device (16). The process (1200) then returns to step (1204) and is repeated until temperature monitoring is terminated.

[0100] In certain embodiments, the process (1200) includes an additional step (1210) of providing a synchronization signal to the temperature measurement device (16) (either by the controller (24) or by an intensity sensor (30) positioned to measure the intensity of radiation emitted by the radiation source (14)) indicating when the radiation source (14) is in an active state and an inactive state such that the temperature measurement device (16) can start and stop temperature measurements in synchronization with switching between the active and inactive states.

[0101] Although embodiments of the present disclosure have been described thus far as having a temperature measuring device (16) synchronized to the switching rate of the radiation source (14) that is electronically controlled by a dedicated controller (24) independent of the temperature measuring device (16), other embodiments are possible in which the controller is integrated as part of the temperature measuring device. Such embodiments are believed to be of particular value when the temperature measuring device is implemented as a temperature probe that is integrated as part of the thermal processing system. In such embodiments, the processor of the temperature monitoring device may be configured to perform the functions of the controller (24) described above (see, e.g., FIGS. 1 and 2), and the controller (24) itself may be removed. Thus, the processor of the temperature measuring device, e.g., processor (18), may control the switching of the radiation source (14) between active and inactive states and provide synchronization for the sensor (20) (or amplifier switch, e.g., switch (21) in FIG. 10).

[0102] The disclosed temperature control / monitoring / measurement methods, instruments and devices are particularly suitable for use with radiation sources (14) implemented as multiple electronically controllable and switchable LEDs or lasers, although the methods, instruments and devices are also useful when deployed with radiation sources (14) implemented as lamps or other incandescent sources. In such implementations, it may be advantageous to add a time delay to the measurement interval start time to account for the time required for residual radiant radiation to dissipate after the lamp or other incandescent source is turned off. The delay may be dynamically included in the synchronization signal or may be programmed into the processor (18) of the temperature measurement device (16). Adding such a delay time to the measurement interval start time may further be used to compensate for delays introduced by other components of the system other than the radiation source itself, but which result in a delay in the time required for the radiation source to reduce its radiation output to a negligible level. For example, the power source of the radiation source may also introduce delays or time dynamics in the reduction of the radiation output by the radiation source, and these delays and time dynamics may also be compensated for by adding a time delay to the measurement interval start time.

[0103] The various sensors described herein are sensors of electromagnetic radiation that may be sensitive to radiation in a particular wavelength band or region of the electromagnetic spectrum. These sensors may also be referred to as "detectors" and may be implemented in a variety of ways, such as, for example, as photodetectors, photosensors, photodiodes, or any other type of sensing device capable of converting sensed electromagnetic radiation into a current or other type of information-bearing signal. In certain embodiments, sensor (20) and / or sensor (30) generate / generate an analog signal in response to the sensed radiation, while in other embodiments, sensor (20) and / or sensor (30) generate / generate a digital signal in response to the sensed radiation. In embodiments in which an analog signal is generated by the sensor(s), an analog-to-digital conversion circuit is preferably in signal communication with the sensor(s) to convert the analog signal to a digital signal.

[0104] As mentioned above, the radiation source (e.g., LED, laser) has a peak emission wavelength that may be different from the wavelength at which the temperature measurement device according to the embodiments disclosed herein is operable. In embodiments where a sensor (e.g., intensity sensor (30)) is utilized to detect the absence or presence of radiation (in the relevant wavelength range) emitted by the radiation source to generate a synchronization signal, it should be understood that such a sensor most preferably operates at or near the peak emission wavelength of the radiation source. In addition, it should be understood that the wavelength values ​​and ranges described above and illustrated in the drawings are merely exemplary and generally provided to more clearly demonstrate the temperature measurement / monitoring methodology of the embodiments of the present disclosure. The teachings according to the embodiments of the present disclosure can be applied to radiation emission and measurement for other wavelength values ​​and ranges, as will be apparent to one of ordinary skill in the art.

[0105] As mentioned above, the apparatus (16) according to the second aspect of the present disclosure is also configured to measure radiation to enable the determination of the reflectance and / or emissivity of the substrate (12). As discussed above, the apparatus (16) is generally configured to measure radiation from the substrate (12) (as well as the environment surrounding the substrate (12)) and therefore can be used in combination with the synchronization method described above to determine and / or calculate and / or monitor and / or measure one or more parameters of the substrate (12) in addition to temperature, including specifically the reflectance and / or emissivity of the substrate (12). The following paragraphs, with continued reference to Figures 1-13B and with particular reference to Figure 14, describe a methodology for determining the reflectance and / or emissivity of the substrate (12) according to this aspect of the present disclosure.

[0106] As a prelude, the reflectance and transmittance of a substrate can be used (as a consequence of the first and second laws of thermodynamics) to determine the emissivity of the substrate (12) according to the following relationship: emissivity=1-reflectance-transmittance.

[0107] In the special case where the measurement apparatus operates in a wavelength range where the transmittance of the substrate is substantially zero (a wavelength range where the substrate is opaque), the emissivity can be determined only by measuring the reflectance of the substrate (since the transmittance is nearly zero).

[0108] Thus, if the reflectance of the substrate (12) can be determined within a wavelength range in which the substrate is substantially opaque, the emissivity of the substrate (12) within that wavelength range can be readily calculated therefrom. According to certain embodiments of the second aspect of the present disclosure, the reflectance of the substrate (12) is first determined, and the emissivity of the substrate (12) is then calculated based on the determined reflectance.

[0109] According to certain embodiments, the reflectivity of the substrate (12) is determined based on measurements (performed by the apparatus (16)) made when the radiation source (14) is in an inactive and active state. The following paragraphs describe certain exemplary ways in which the substrate reflectivity may be determined from the measurements in the inactive and active states.

[0110] Referring to FIG. 14, when the radiation source is in an inactive state, the measurement device (16) collects thermal radiation from the substrate (12). This radiation is represented by the wavy arrow (32). When the radiation source is switched to an active state, the measurement device (16) continues to collect thermal radiation emitted by the substrate (12), and further collects (a) radiation emitted by the radiation source (14) after reflection from the substrate (12), as represented by the thick dashed arrow (34), and (b) radiation emitted by the radiation source (14) that impinges on the measurement device (16) without first reflecting from the substrate (12), as represented by the thin dotted arrow (35). It will be understood that the arrows shown in FIG. 14 merely represent exemplary paths that may be taken by each class of radiation described in this paragraph.

[0111] The radiation intensity incident on the device (16) when the radiation source (14) is inactive is I inactive The radiation source has a power P reflectivityThe radiation intensity incident on the device (16) when it is active at a particular power setting will be referred to as I active The difference between these two signals is I difference =I active -I inactive It is noted that θ is independent of the intensity of the thermal self-radiation being emitted by the substrate (12), but contains information about the radiation intensity (34) reflected from the substrate (12).

[0112] I difference A calibration procedure must be performed to convert σ to a reflectance value representative of the reflectance of the substrate 12. There are many possibilities how to calibrate this measurement, and one exemplary method is described here as follows.

[0113] Known reflectance ρ ref1 and ρ ref2 When each of the two substrates (12) is placed in the system (10), difference The I difference The two values ​​of (reflectance ρ ref1 and ρ ref2 (corresponding to the measured value of the board)I diff1 and I diff2 For example, typically in semiconductor processing applications, a bare silicon wafer is irradiated with light having a known reflectance ρ ref1 = 0.32 can be used as a reference substrate. Another reference reflectance can be, for example, when the substrate (12) is completely removed, resulting in a ρ ref2 = 0. (Note that in this case, it may be necessary in some system designs to also remove the reflective surface immediately behind the substrate 12, which may reflect radiation back into the device 16 even in the absence of the substrate 12.) The general reflectance ρ of any substrate placed in the system 10 can then be calculated as follows:

[0114]

number

[0115] where the constants C1 and C2 are given in terms of calibration measurements as follows:

[0116]

number

[0117] The above equations are appropriate for situations where the reflected radiation (34) collected by the measurement device (16) typically undergoes only one reflection from the substrate (12) before impinging on the measurement device (16). If the geometry of the system (10) is such that a significant intensity of the reflected radiation (34) undergoes multiple reflections from the substrate (12) before impinging on the measurement device (16), then the above equations must be modified to account for the effects of these multiple reflections. These effects of multiple reflections are referred to as "cavity effects," and the mathematical formulas for modifying the above equations to account for these effects are well known to those skilled in the art.

[0118] Now consider the general case where it is desired to perform all of the following three operations during the processing of a given substrate (12): (a) heat the substrate to a desired temperature profile, (b) measure the substrate temperature (or thermal self-emission), and (c) measure the reflectance of the substrate (and therefore the emissivity of an opaque substrate). The required operations are respectively: (a) activate the radiation source at a power setting expected to result in the desired substrate heating profile, and (b) periodically deactivate the radiation source to measure the temperature (and I for reflectance measurements). inactive ) and (c) the power setting P reflectivity The radiation source is activated with the reflectance measurement I active Measure.

[0119] It should be noted that the three measurements described in the previous paragraph do not need to be performed at the same frequency, since substrate emissivity (and reflectivity) is expected to vary very slowly with substrate temperature. In general, it is expected that the majority (>80%) of the processing time will be allocated to (a) heating the wafer to the desired temperature profile. The remaining <20% of the processing time will be allocated to measuring the temperature (thermal self-emission) and emissivity (reflectivity) of the substrate (12), with the temperature measurements being performed significantly more frequently than the emissivity measurements. For example, if the substrate emissivity is expected to vary only weakly as a function of temperature, it may be advantageous to measure the emissivity only once as the substrate enters the processing system (10), and then only heat the substrate (12) and measure its temperature, without repeating the reflectivity measurements during the processing of the substrate. Alternatively, the emissivity of the substrate (12) may be measured during the processing of the substrate, for example, once every 10 temperature measurements.

[0120] Although the present invention has been described in the context of a thermal processing system used to heat process substrates, the temperature measurement / monitoring / tracking methods described herein are applicable to any thermal processing process in which it is necessary to measure / monitor / track the temperature of a workpiece while it is being heated at least intermittently or cyclically by one or more radiation sources.

[0121] As mentioned above, in certain wafer processing systems, the radiation source (14) causes the substrate (12) to heat and generates radiation, but there is no causal relationship between the radiation generated when the radiation source (14) is active and the heating of the substrate (12). In other words, in certain cases, the radiation source (14) itself is not the radiation source that irradiates the substrate (12) so as to heat it, and the radiation generated as a result of (caused or resulting from) the radiation source (14) being active is not the cause of the heating of the substrate, but is a by-product or side effect of some other aspect of the wafer process. A plasma etching or plasma deposition system is an example of such a process, where the wafer is heated by physical bombardment of the wafer by charged particles in the plasma. Furthermore, the collisions of these particles with each other and with the wafer generate radiation (i.e., emission of radiation), which can interfere with wafer temperature measurements. However, the radiation generated is not the cause of the heating of the wafer, but is a by-product of particle bombardment. However, in order to accurately measure / sense the thermal radiation of the wafer, it may be useful to be able to turn off the plasma to eliminate interfering plasma radiation during wafer temperature measurement.

[0122] Thus, and as discussed above, the radiation source (14) according to embodiments of the present disclosure is not necessarily limited to a radiation source that irradiates the substrate, but is generally a radiation source that causes heating of the substrate (12) when in an active state. Moreover, the inactive state more generally corresponds to a state in which the radiation source (14) generates substantially no radiation or generates a negligible amount of radiation so as not to interfere with substrate temperature measurements. In certain particularly preferred embodiments, the radiation source (14) is a radiation source such as an LED or laser that irradiates the substrate and thereby heats it, and can be controlled to turn on and off rapidly such that the radiation source emits no radiation or emits a negligible amount of radiation when in an inactive state. In other embodiments, the radiation source (14) causes heating of the substrate when in an active state, for example when implemented as a plasma in the case of a plasma etching or plasma deposition system. In such embodiments, the radiation source (14) causes substantially no radiation or a negligible amount of radiation to be generated when the radiation source is in an inactive state, which in the example where the radiation source is a plasma refers to a state in which charged particles are not impinging on the wafer, and prevents the charged particles from colliding with each other or the wafer, thereby causing no radiation or a negligible amount of radiation to be generated.

[0123] The description of various embodiments of the present disclosure has been presented for illustrative purposes, but is not intended to be exhaustive and limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terms used in this specification have been selected to best explain the principles of the embodiments, practical applications or technical improvements over the technology found in the market, or to enable those skilled in the art to understand the embodiments disclosed herein.

[0124] As used herein, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

[0125] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments and / or does not necessarily exclude the incorporation of features from other embodiments.

[0126] It will be appreciated that certain features of the invention that are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention that are, for clarity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination, or as appropriate in any other described embodiment of the invention. Certain features that are described in the context of various embodiments are not considered essential features of an embodiment, unless the embodiment can be practiced without those elements.

[0127] To the extent that the appended claims have been drafted without multiple dependencies, this has been done solely to accommodate formal requirements in jurisdictions that do not allow such multiple dependencies. It should be noted that all possible combinations of features implied by making the claims multiple dependent are expressly contemplated and should be considered part of the present invention.

[0128] While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications, and variations that fall within the spirit and broad scope of the appended claims.

Claims

1. 1. A method for measuring a temperature of a substrate, comprising: one or more radiation sources having a response time defined by rise and fall times of less than 100 milliseconds; an active state in which the one or more radiation sources heat at least a portion of the substrate; a deactivated state in which the one or more radiation sources generate substantially no radiation or generate a negligible amount of radiation; and switching between performing a temperature measurement of at least one portion of the substrate by a temperature measurement device, the temperature measurement device comprising: (A) the one or more radiation sources are switched from the active state to the inactive state within the response time, and the temperature measurement is initiated immediately after the one or more radiation sources are switched to the inactive state; (B) immediately after completion of the temperature measurement, the one or more radiation sources are switched from the inactive state to the active state within the response time; (C) the temperature measurements are performed only when the one or more radiation sources are in the inactive state. and synchronizing switching between the active and inactive states such that

2. The method of claim 1 , wherein the one or more radiation sources irradiate the substrate during the active state so as to heat the substrate.

3. The method of claim 1 , wherein the one or more radiation sources comprise a plurality of light emitting diodes or a plurality of laser radiation sources arranged to irradiate the substrate.

4. The method of claim 1 , wherein the one or more radiation sources comprise a plasma configured to bombard the substrate with charged particles during the active state.

5. 2. The method of claim 1 , wherein the temperature measurement device is synchronized to switching between the active state and the inactive state via a synchronization signal corresponding to at least one of the inactive state, a transition from the active state to the inactive state, or a transition from the inactive state to the active state.

6. The method of claim 5 , wherein the synchronization signal is provided by an intensity sensor disposed to sense radiation emitted by the one or more radiation sources.

7. The method of claim 5 , wherein the synchronization signal is provided by a controller associated with the one or more radiation sources that controls switching of the one or more radiation sources between the active and inactive states.

8. 2. The method of claim 1, wherein the temperature measurement device includes a sensor that senses radiation emitted by the one or more radiation sources and is synchronized to switching of the one or more radiation sources between the active and inactive states by identifying a drop in emitted radiation that corresponds to a start of the inactive state.

9. 2. The method of claim 1, wherein the active state is associated with at least one irradiation time interval, each of the at least one irradiation time interval being a time interval during which the one or more radiation sources emit radiation at an output power, or an average output power taken over a time interval, that is high enough to heat the substrate, and the inactive state is associated with at least one measurement time interval, each of the at least one measurement time interval being a time interval during which the one or more radiation sources do not emit radiation or emit radiation at an output power that is low enough that it can be ignored by the temperature measurement device.

10. 1. A system for measuring a temperature of a substrate, comprising: one or more radiation sources disposed in association with the substrate, the one or more radiation sources having a response time defined by rise and fall times of less than 100 milliseconds, the one or more radiation sources being switchable between an active state in which the one or more radiation sources heat at least a portion of the substrate, and an inactive state in which the one or more radiation sources generate substantially no radiation, or a negligible amount of radiation; a controller including at least one processor and configured to switch the one or more radiation sources between the active state and the inactive state; a temperature measurement device configured to perform a temperature measurement of at least one portion of the substrate, wherein the temperature measurement device and switching between the active state and the inactive state include: (A) the one or more radiation sources are switched from the active state to the inactive state by the controller within the response time, and the temperature measurement is initiated immediately after the one or more radiation sources are switched to the inactive state; (B) immediately after completion of the temperature measurement, the one or more radiation sources are switched by the controller from the inactive state to the active state within the response time; (C) the temperature measurements are performed only when the one or more radiation sources are in the inactive state. and a temperature measurement device, the temperature measurement device and the temperature measurement device being synchronized with each other so as to

11. 11. The system of claim 10, wherein the temperature measurement device is synchronized to switching of the one or more radiation sources via a synchronization signal corresponding to at least one of the inactive state, a transition from the active state to the inactive state, or a transition from the inactive state to the active state.

12. The system of claim 11 , wherein the synchronization signal is provided to the temperature measurement device by the controller.

13. The system of claim 11 , further comprising at least one intensity sensor disposed to sense radiation emitted by the one or more radiation sources.

14. The system of claim 13 , wherein the at least one intensity sensor provides the synchronization signal to the temperature measurement device.

15. The system of claim 10 , wherein the temperature measurement device is synchronized to switching of the one or more radiation sources by measuring radiation and identifying a drop in the measured radiation that corresponds to the onset of the inactive state.

16. The system of claim 10 , wherein the one or more radiation sources irradiate the substrate during the active state so as to heat the substrate.

17. The system of claim 10 , wherein the one or more radiation sources include a plurality of light emitting diodes or a plurality of laser radiation sources.

18. The system of claim 10 , wherein the one or more radiation sources include a plasma configured to bombard the substrate with charged particles during the active state.

19. 11. The system of claim 10, wherein the active state is associated with at least one irradiation time interval, each of the at least one irradiation time interval being a time interval during which the one or more radiation sources emit radiation at an output power or an average output power taken over a time interval that is high enough to heat the substrate, and the inactive state is associated with at least one measurement time interval, each of the at least one measurement time interval being a time interval during which the one or more radiation sources emit no radiation or emit radiation at an output power that is low enough that it can be ignored by the temperature measurement device.

20. A method for measuring thermal radiation emitted by a substrate, comprising the steps of: one or more radiation sources having a response time defined by rise and fall times of less than 100 milliseconds; an active state in which the one or more radiation sources heat the substrate; a deactivated state in which the one or more radiation sources generate substantially no radiation or generate a negligible amount of radiation; and switching between performing a measurement of the thermal radiation emitted by the substrate by a thermal radiation measuring device, the thermal radiation measuring device comprising: (A) the one or more radiation sources are switched from the active state to the inactive state within the response time, and the measurement of the thermal radiation is initiated immediately after the one or more radiation sources are switched to the inactive state; (B) immediately upon completion of the measurement of the thermal radiation, the one or more radiation sources are switched from the inactive state to the active state within the response time; (C) the measurement of thermal radiation is performed only when the one or more radiation sources are in the inactive state. and synchronizing switching between the active state and the inactive state such that

21. The method of claim 20, further comprising calculating a temperature of the substrate based on the measured thermal radiation.

22. The method of claim 1 , wherein the one or more radiation sources are disposed between the temperature measurement device and the substrate.

23. The system of claim 10 , wherein the one or more radiation sources are disposed between the temperature measurement device and the substrate.

24. The method of claim 20 , wherein the one or more radiation sources are disposed between the thermal radiation measuring device and the substrate.

25. the temperature measurement device includes at least one sensor for detecting radiation emitted by the substrate and generating a temperature indicative signal in response thereto; The method of claim 1 , further comprising amplifying the generated temperature indicative signal only during periods when the one or more radiation sources are in the inactive state.

26. the temperature measurement device includes at least one sensor for detecting radiation emitted by the substrate and generating a temperature indicative signal in response thereto; 11. The system of claim 10, further comprising a switchable amplifier circuit configured to amplify the generated temperature indicative signal only during periods when the one or more radiation sources are in the inactive state.

27. the thermal radiation measuring device includes at least one sensor for detecting thermal radiation emitted by the substrate and generating a temperature indicative signal in response thereto; 21. The method of claim 20, further comprising amplifying the generated temperature indicative signal only during periods when the one or more radiation sources are in the inactive state.

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