Method of determining a change of a presence state of a substrate, and presence sensor system

Abstract

A method of determining a change of a presence state of a substrate in a processing chamber is provided. The method comprises measuring a first signal of a first infrared sensor over time, a field of view of the first infrared sensor facing towards a substrate transport path in the processing chamber; and analyzing a temporal evolution of the first signal for determining if the presence state of the substrate has changed.

Description

METHOD OF DETERMINING A CHANGE OF A PRESENCE STATE OF A SUBSTRATE, AND PRESENCE SENSOR SYSTEMTECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to methods and apparatuses for determining a change of a presence state of a substrate in a processing chamber. More particularly, embodiments of the present disclosure relate to using a signal of an infrared sensor and the temporal evolution of the signal to determine a change of the presence state of the substrate. Embodiments of the present disclosure specifically relate to presence sensor systems for a processing chamber to determine a change of the presence state of the substrate in the processing chamber.BACKGROUND

[0002] In a processing chamber, in particular a deposition chamber, for depositing materials on a substrate, exemplarily by vapor deposition, determining the presence of the substrate at a deposition position is relevant to ensure a reproducible and reliable deposition process. A malfunction in a transport of the substrate through the deposition chamber may be associated with the substrate being positioned at a position not suitable for deposition. Similarly, determining a substrate exiting the deposition chamber, and the deposition position being empty, exemplarily allows to operate the deposition chamber in an idle mode.

[0003] To determine conditions in the deposition chamber, a plurality of sensors may be used. Exemplarily, a temperature of the substrate or of the deposition chamber may be measured by a temperature sensor and a position of the substrate may be measured by another sensor.

[0004] Each sensor used in the deposition chamber is prone to a malfunction and adds cost and complexity, in particular with respect to wiring or chamber wall passagesrequired.

[0005] In view of the above, methods of determining substrate properties with a reduced number of sensors would be beneficial.SUMMARY

[0006] In light of the above, methods of determining a change of a presence state of a substrate in a processing chamber are provided according to the independent claims. Further aspects, benefits, and features of the present disclosure are apparent from the claims, the description, and the accompanying drawings.

[0007] According to an aspect, a method of determining a change of a presence state of a substrate in a processing chamber is provided. The method comprises measuring a first signal of a first infrared sensor over time, a field of view of the first infrared sensor facing towards a substrate transport path in the processing chamber; and analyzing a temporal evolution of the first signal for determining if the presence state of the substrate has changed.

[0008] In particular, the field of view of the sensor faces towards a back side of the substrate transport path, such that an infrared emission signal of the back side of the substrate is measured when a substrate is present in the field of view.

[0009] In particular, analyzing the temporal evolution of the first signal comprises analyzing a time derivative of the first signal.

[0010] In particular, analyzing the temporal evolution of the first signal comprises using a trained machine learning, ML, model for recognizing a pattern associated with a change of the presence state of the substrate.

[0011] According to another aspect, a presence sensor system for a processing chamber is provided. The presence sensor system comprises an infrared sensor; and a presence state determining unit; wherein the presence state determining unit is configured for executing the method of any of the embodiments described herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the disclosure and are described in the following:

[0013] FIG. 1 shows a schematic view of a processing chamber with a first infrared sensor according to embodiments;

[0014] FIG. 2 shows a schematic view of a processing chamber with a first infrared sensor and a second infrared sensor according to embodiments;

[0015] FIG. 3 shows an exemplary temporal evolution of a signal of an infrared sensor according to embodiments;

[0016] FIG. 4 shows an exemplary time derivative of a temporal evolution of a signal of an infrared sensor according to embodiments;

[0017] FIG. 5 shows an exemplary temporal evolution of a signal of an infrared sensor according to embodiments;

[0018] FIG. 6 schematically depicts a method for determining a change of a presence state of a substrate in a processing chamber according to embodiments.DETAILED DESCRIPTION

[0019] Reference will now be made in detail to the various embodiments, one or more examples of which are illustrated in each figure. Each example is provided by way of explanation and is not meant as a limitation. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with any other embodiment to yield yet a further embodiment. It is intended that the present disclosure includes such modifications and variations. Within the following description of the drawings, the same reference numbers refer to the same or to similar components. Generally, only the differences with respect to the individualembodiments are described. Unless specified otherwise, the description of a part or aspect in one embodiment can apply to a corresponding part or aspect in another embodiment as well.

[0020] FIG. 1 schematically shows a processing chamber 120 with, for example, a deposition source 121 according to embodiments described herein. A substrate 110 may be transported through the processing chamber 120 along a substrate transport path 111 in a transport direction T. A first infrared sensor 101 is attached to the processing chamber 120. A field of view of the first infrared sensor 101 faces the substrate transport path 111. The first infrared sensor 101 is connected to a presence state determining unit 105. Embodiments described herein, refer to a deposition as an option of a substrate processing. However, other substrate processing operations, such as cleaning, heating, annealing, etching, or the like may also be provided.

[0021] The processing chamber 120 may be a vacuum processing chamber, particularly configured for vacuum deposition of materials on a substrate. The term "vacuum", as used herein, can be understood in the sense of a technical vacuum having a vacuum pressure of less than, for example, 10 mbar. During a vapor deposition process, the pressure in the vacuum chamber may be between 10’2mbar and 10’4mbar, particularly between 2*1 O’3mbar and 6*1 O’3mbar. In an idle mode, the pressure in the vacuum chamber may be below 10’6mbar.

[0022] The processing chamber 120 may include a substrate transportation system configured to move the substrate 110 along a substrate transport path 111 in a transport direction T past the deposition source 121 and past other optional further deposition sources. The substrate transportation system may move the substrate along a substrate transport path 111 in a positive and / or negative transport direction T. The substrate transport path 111 may be configured for substrate transport, e.g. in the form of a roller transportation system, one or more linear motors and / or a magnetic levitation system suitable for moving the substrate relative to and past the deposition sources. The substrate may be carried by a substrate carrier during the transport and / or deposition. The substrate carrier may comprise materials different from materials of the substrate. In particular, the substrate carrier may have a different emissivity than the substrate. The substrate carrier may comprise aluminum ortitanium. In some embodiments, the substrate carrier may consist of aluminum or titanium. According to some embodiments, the substrate transport system may comprise a substrate-carrier less system. In particular, the substrate transport system may comprise a robot configured to transport the substrate into the processing chamber, exemplarily by a robot fork.

[0023] The processing chamber 120 may comprise walls made from steel, particularly stainless steel. The processing chamber 120, in particular the inner walls of the processing chamber 120, may have a different emissivity than the substrate 110. The processing chamber 120, in particular the inner walls of the processing chamber 120, may have a different emissivity than the substrate carrier. The processing chamber 120 may comprise openings in chamber walls to attach sensors, in particular to attach the first infrared sensor 101 .

[0024] In some embodiments, the substrate 110 may be a glass substrate. In particular, the substrate may be substrate for a thin film transistor (TFT). The glass substrate may not be transparent for infrared light, in particular not for infrared light of a wavelength exceeding 2.0 pm, 2.5 pm, 3 pm, 5 pm, 6 pm, 8 pm, or 10 pm. The substrate may be considered as not being transparent if the transmission of light at a selected wavelength does not exceed 30%. The substrate 110 not being transmissive may advantageously allow to distinguish infrared signals originating from the substrate and infrared signals originating from processing chamber 120 components, such as the processing chamber wall, that are in a field of view 103 of the first infrared sensor 101 when no substrate 110 is present. In particular, infrared signals originating from processing chamber 120 components may not pass through the substrate 110.

[0025] The substrate 110 may comprise a front side and a back side. On the substrate transport path 111 , the front side of the substrate may face towards the deposition source 121 (or another substrate processing tool). The back side opposed the front side. According to some embodiments described herein, the first infrared sensor 101 may measure the back side of the substrate. The deposition source 121 and the first infrared sensor 101 may be positioned on opposite sides of the substrate transport path 111 , and, in particular, on opposite sides of the substrate. Measuring the back side of the substrate by the first infrared sensor 101 may advantageouslyallow to measure the infrared signal emitted by the substrate 110 independently from the deposition process and independently of layers or layer stacks provided on the front side of the substrate. In particular, the emissivity of the substrate 110 may not be influenced by layers deposited on the substrate 110 by a previous process or the deposition source 121.

[0026] The first infrared sensor 101 may be a passive infrared sensor. The first infrared sensor 101 may be an infrared sensor configured to measure a temperature. In particular, the first infrared sensor 101 may be configured to measure a temperature of the substrate 110. The first infrared sensor 101 may be a pyrometer. The first infrared sensor 101 may be a mid-infrared sensor. Mid-infrared light may in particular comprise light of a wavelength of 8 pm to 14 pm. The first infrared sensor may be particularly sensitive to infrared light emitted with a wavelength exceeding 2.0 pm, 2.5 pm, 3 pm, 5 pm, 6 pm, 8 pm or 10 pm. In some embodiments, the first infrared sensor may not be sensitive for infrared light with a wavelength exceeding 11 pm, 14 pm or 16 pm. In some embodiments, the first infrared sensor may comprise a filter element configured to filter the infrared light emitted by the substrate and / or the processing chamber spectrally. In particular, the filter element may block infrared light transmitted by the substrate. Blocking infrared light transmitted by the substrate may advantageously allow to separate infrared signals originating from the substrate 110 from infrared signals originating from the processing chamber 120, exemplarily from the inner walls of the processing chamber 120. The first infrared sensor 101 may be attached to the processing chamber 120. In some embodiments, the first infrared sensor 101 may be within the processing chamber 120.

[0027] The first infrared sensor 101 may be connected to a presence state determining unit 105. The presence state determining unit 105 determines the presence state of the substrate 110. The presence state determining unit 105 may receive the first signal of the first infrared sensor 101 . The presence state determining unit 105 may receive additional signals from components of the processing chamber 120, exemplarily from a transport apparatus such as the substrate transport system or additional sensors of the processing chamber 120.

[0028] In some embodiments, the presence state determining unit 105 may receivea trigger signal, particularly to start or to end analyzing the temporal evolution of the first signal. In other words, the trigger signal may restrict the temporal evolution of the first signal to a time window around a predefined event. The predefined event may comprise an end of a deposition process, a state of the transport apparatus, exemplarily a state that indicates that the transport apparatus is moving the substrate 110, a change of the state of the transport apparatus, a presence state of another processing chamber and / or a change of the presence state of another processing chamber.

[0029] The presence state determining unit 105 may analyze the first signal. The presence state determining unit 105 may analyze the temporal evolution of the first signal, in particular, changes in the intensity of the first signal. In FIG 3 and FIG 5, exemplary signals of an infrared sensor, in particular of the first infrared sensor, are shown. In FIG 4, an exemplary time derivative of a signal of an infrared signal, in particular of the first signal, is shown. Before a substrate enters the field of view of the infrared sensor, a substantially constant infrared signal is present. When the substrate enters the field of view of the infrared sensor, infrared radiation originating from the substrate may be measured. In some embodiments, infrared radiation of the processing chamber may, at least partially, be blocked by the substrate. As described below, the infrared signal may change when the substrate enters the field of view of the infrared sensor. The presence state determining unit may analyze the change of the infrared signal to determine whether the presence state has changed, in particular from “not present” to “present”. Heating of the substrate results in an increase of the infrared signal of the substrate. After heating, the substrate may cool and the infrared signal may decrease. When the substrate exits the field of view of the infrared sensor, the infrared signal may decrease. The presence state determining unit may analyze the change of the infrared signal to determine whether the presence state has changed, in particular from “present” to “not present”.

[0030] In FIG 2, the embodiment of FIG 1 is shown, but further comprises a second infrared sensor 201 . The second infrared sensor 201 has a second field of view 203. The second field of view 203 may not overlap with the field of view 103 of the first infrared sensor 101. In particular, the first infrared sensor 101 and the second infrared sensor 201 may be positioned on opposite edges of the processing position of thesubstrate 110. The processing position may be a position in which the substrate is during processing, e.g. deposition, in the processing chamber 120. For example, the processing position may be a part of the substrate transport path 111.

[0031] The second infrared sensor 201 may have the same properties as the first infrared sensor 101. In some embodiments, the second infrared sensor 201 may be of a different type than the first infrared sensor 101 . In some embodiments, the presence sensor system may comprise a plurality of second infrared sensors. A field of view of each of the plurality of second infrared sensors may face towards the substrate transport path 111 in the processing chamber 120.

[0032] The first infrared sensor and / or the second infrared sensors may comprise a thermography apparatus, in particular to spatially resolve the emitted infrared light and / or the sensor signal. Spatially resolving the emitted infrared light, or the infrared signal, may advantageously allow to obtain an additional dimension for determining if the presence state of a substrate has changed. Exemplarily, a movement of the substrate 110 may be observed and analyzed. In some embodiments, the spatially- resolved sensor signal may be analyzed to determine an integrity state of the substrate. The integrity state of the substrate may comprise the presence or absence of cracks, the presence or absence of contamination and / or the presence or absence of chips at the substrate 110, in particular, at edges of the substrate 110. In some embodiments, the integrity state may comprise an orientation of the substrate 110 in the substrate carrier.

[0033] The presence state determining unit 105 may be connected to the second infrared sensor 201 and may receive a second signal of the second infrared sensor 201. In some embodiments, the presence state determining unit 105 receives additional second signals from the plurality of second infrared sensors.

[0034] The presence state determining unit 105 may determine the presence state of the substrate 110 by analyzing the temporal evolution of the first signal of the first infrared sensor 101 and of the second signal of the second infrared sensor 201. In particular, the presence state determining unit 105 may analyze differences in the temporal evolution of the first signal of the first infrared sensor 101 and of the second signal of the second infrared sensor 201. Exemplarily, the presence state determiningunit 105 may analyze a difference in the signal of the first infrared sensor 101 and / or in the second signal of the second infrared sensor 201 over time. The presence state determining unit may compare the difference in the signal of the first and / or second infrared sensor over time with information received from components of the processing chamber 120, exemplarily from the transport apparatus.

[0035] The presence state determining unit 105 may comprise a controller. The controller may comprise an interface for providing information to the controller. In particular, providing information to the controller may comprise providing an emissivity value of the substrate 110, and optionally providing an emissivity value of the substrate carrier and / or the wall of the processing chamber 120 to the controller. The controller may be configured to calculate a temperature from a signal of an infrared sensor, in particular from the first signal of the first infrared sensor 101 , and / or from the second signal of the second infrared sensor 201. The controller may employ the emissivity value provided to determine the temperature.

[0036] In some embodiments, the interface may comprise a graphic-user interface (GUI), configured to receive a user input. The GUI may receive the emissivity value from the user and may display the temperature to the user. In some embodiments, the interface may be an Internet of Things, loT, interface. In particular, the interface may be configured to receive the emissivity value from the substrate and / or the substrate carrier. In other words, the substrate or substrate carrier may comprise a label indicating the emissivity value of the substrate, and, in some embodiments, of the substrate carrier. This may advantageously allow to automatically obtain emissivity values for a plurality of substrate types, in particular if the substrate comprises layers that may affect the emissivity.

[0037] FIG 3 exemplarily shows a signal 300 of an infrared sensor over time according to embodiments described herein. In particular, FIG 3 shows an intensity 320 of the signal 300 of the infrared sensor over time 310. The signal 300 may be the first signal of the first infrared sensor or the second signal of the second infrared sensor or a second signal of one of the plurality of second infrared sensors. The signal 300 may be an electrical signal. In some embodiments, the signal 300 may be a calibrated signal. In some embodiments, the signal 300 may be a temperature signal, in particulara temperature signal of the substrate. In other words, the signal 300 may be calibrated by the emissivity value of the substrate.

[0038] In some embodiments, the infrared sensor may provide the signal 300 with the time 310. In particular, for each value of the signal 300, a respective time 310 is provided by the infrared sensor. In some embodiments, the time 310 is added to the signal 300 in a processing step, exemplarily by the presence state determining unit.

[0039] In an exemplary deposition process, with the substrate entering the processing chamber, a deposition process taking place and the substrate leaving the processing chamber, a number of characteristic signals may occur. Before the substrate enters the field of view of the infrared sensor, the processing chamber may be in an idle configuration 301. The infrared sensor collects infrared radiation emitted by components of the processing chamber, exemplarily by the wall of the processing chamber and / or by cathodes. In the idle configuration, the temperature of the chamber components in the field of view of the infrared sensor may be stable, leading to a constant signal 300. Once the substrate enters the field of view of the infrared sensor, the signal of the infrared sensor changes. With the substrate and the chamber components in the field of view being of a different material, in particular the substrate being a glass and the chamber components being stainless steel or aluminum, their emissivity differs. In particular, for the processing chamber being heated, and the substrate being at a different temperature prior to entering the processing chamber, the signal of the infrared sensor may predominantly change due to a difference in temperature of the substrate and the processing chamber. In particular, the emissivity of the substrate may exceed the emissivity of the chamber components, exemplarily by a factor of at least 1 .2, 1 .5, 2, 3, 4 or 5. The emissivity of the substrate may exceed 0.85, 0.90, 0.92 or 0.95. The emissivity of the chamber components may be lower than 0.8, 0.6, 0.5, 0.4, 0.3, 0.2 or 0.15. At the same, or at least at a similar temperature, an increase of the signal 300 may be observed when the substrate enters the field of view of the infrared sensor. This advantageously allows to identify a substrate entering the field of view of the infrared sensor.

[0040] Once a coverage of the field of view by the substrate does not change anymore, a period 303 of time may lapse until the deposition process starts. Duringthe period 303, the temperature of the substrate and the intensity of the signal 300 remain constant. In some embodiments, the substrate may be moved into the processing position during the period 303. During, for example, the deposition process 304, the temperature of the substrate increases. As the temperature of the substrate increases, the intensity of the signal 300 increases as well. The temperature of the substrate may be calculated from the signal 300, exemplarily by the presence state determining unit using the emissivity of the substrate. After the deposition process 304, the substrate may cool 305. During the cooling process 305, the temperature of the substrate decreases. As the temperature of the substrate decreases, the infrared emission and the signal 300 of the substrate decrease.

[0041] After the deposition process 304 and the cooling process 305, the substrate exits 306 the field of view of the infrared sensor. The signal 300 may decrease due to the higher emissivity of the substrate in comparison with the components of the processing chamber. After the substrate leaves the field of view of the infrared sensor, the processing chamber may be in an idle configuration 307, similar to the idle configuration 301 . The deposition process starts again with another substrate entering 308 the field of view of the infrared sensor.

[0042] In some embodiments, as exemplarily shown in FIG 5, depending on the temperature of the substrate prior to entering the processing chamber and depending on the temperature of the components of the processing chamber, the substrate entering 302, 308 the field of view of the infrared sensor may be associated with a decrease of the signal 300 of the infrared sensor. Whether the substrate entering 302, 308 the field of view of the infrared sensor is associated with the signal 300 decreasing or increasing is associated with the temperatures of the substrate, the components of the processing chamber and the emissivity of the substrate and the components of the processing chamber.

[0043] In some embodiments, depending on the temperature of the substrate prior to exiting the processing chamber and depending on the temperature of the components of the processing chamber, the substrate exiting 306 the field of view of the infrared sensor may be associated with an increase of the signal 300 of the infrared sensor. Whether the substrate exiting 306 the field of view of the infrared sensor isassociated with the signal 300 decreasing or increasing is associated with the temperatures of the substrate, the components of the processing chamber and the emissivity of the substrate and the components of the processing chamber. As shown in FIG 5, the signal 500 may decrease upon exiting 306 the field of view of the infrared sensor if the temperature of the substrate when exiting 306 the field of view exceeds the temperature of the substrate when entering 302, 308 the field of view of the infrared sensor.

[0044] In some embodiments, as exemplarily shown in FIG 5, entering and exiting the field of view of the infrared sensor by the substrate may be associated with the signal 500 decreasing. In particular, the signal 500 may decrease for both entering 302, 308 and exiting 306 the field of view if the temperature of the substrate during exiting 306 substantially exceeds the temperature of the substrate. In some embodiments, entering and exiting the field of view of the infrared sensor by the substrate may be associated with the signal 300 increasing.

[0045] FIG 4 exemplarily shows a value 420 of a time derivative 400 of a signal of an infrared sensor over time 310, according to embodiments described herein. In particular, in FIG 4, the time derivative 400 schematically is the time derivative of the signal 300 of FIG 3. In FIG 4, a constant signal of the infrared sensor is associated with the time derivative 400 being on the zero line 421. A positive time derivative is associated with the signal increasing over time 310, a negative time derivative is associated with the signal decreasing over time 310. During phases with an idle configuration 301 , 307 of the deposition process, the time derivative is substantially zero. In particular, the temperature in the processing chamber does not significantly change over time. During the substrate entering 302, 308 the field of view of the processing chamber, the time derivative has a constant non-zero value. From the constant non-zero value, a velocity of a transport of the substrate along the substrate transport path 111 may be determined, in particular using information on the geometry of the field of view of the infrared sensor and the substrate transport path. The velocity determined may be compared with a velocity provided by the substrate transport system.

[0046] During the deposition process 304, the time derivative 400 of the signal maycontinuously evolve, in particular, decrease while remaining overall positive. During the cooling 305 of the substrate after the deposition process, the time derivative is negative with the absolute value of the time derivative decreasing over time.

[0047] During the substrate exiting 306 the field of view of the infrared sensor, the time derivative has a constant non-zero value. From the constant non-zero value, a velocity of a transport of the substrate along the substrate transport path 111 may be determined, in particular, using knowledge on the geometry of the field of view of the infrared sensor and the substrate transport path. The velocity determined may be compared with a velocity provide by the substrate transport system.

[0048] In the embodiment shown in FIG 4, the time derivative is positive for the substrate entering 302, 308 the field of view of the infrared sensor and negative for the substrate exiting 306 the field of view of the infrared sensor. In some embodiments, the absolute value of the time derivative for the substrate entering 302, 308 and for the substrate exiting 306 the field of view of the infrared substrate may be the same. In particular, the same absolute value may indicate that the velocity of the transport is the same for entering 302, 308 as well as for exiting 306 the field of view of the infrared sensor.

[0049] In some embodiments, both the substrate entering 302, 308 as well as the substrate exiting 306 the field of view may be associated with a negative time derivative 400. In some embodiments, both the substrate entering 302, 308 as well as the substrate exiting 306 the field of view may be associated with a positive time derivative 400.

[0050] The substrate exiting 306 the field of view of the infrared sensor may be associated with a change in the presence state of the substrate. In particular, the presence state may change from “present” to “not present”. The substrate entering 302, 308 the field of view of the infrared sensor may be associated with a change in the presence state of the substrate. In particular, the presence state may change from “not present” to “present”.

[0051] FIG 6, schematically depicts the method 600 for determining a change of a presence state of a substrate in a processing chamber. A first signal of the first infraredsensor is measured 610 over time. The temporal evolution of the first signal of the first infrared sensor is analyzed 620. It is determined 630 if the presence state of the substrate has changed.

[0052] Analyzing the temporal evolution of the first signal for determining if the present state of the substrate has changed may comprise analyzing a raw first signal of the first infrared sensor. Similarly, a raw signal of the plurality of second sensors may be analyzed. A raw signal of the infrared sensor may be a signal that has not been calibrated or processed, in particular, the raw signal of an infrared temperature sensor may be the infrared signal before calculating a temperature.

[0053] Analyzing the temporal evolution of the first signal for determining if the present state of the substrate has changed may comprise analyzing the time derivative of the first signal. In particular, analyzing the time derivative may comprise comparing the absolute value of the time derivative with a first threshold value. In some embodiments, the time derivative exceeding the first threshold value is associated with a change in the presence state. In some embodiments, exceeding the first threshold over a predefined period of time is associated with a change in the presence state. The first threshold may be defined by settings of the processing chamber, the substrate transport system or the infrared sensor. In particular, the first threshold may be tailored to reflect a standard velocity of the substrate along the substrate transport path.

[0054] In some embodiments, analyzing the temporal evolution of the first signal for determining if the present state of the substrate has changed may comprise analyzing a combination of the first signal and the time derivative of the first signal. In particular, the absolute value of the time derivative of the first signal exceeding the first threshold and the absolute value difference of the first signal exceeding a second threshold value is associated with a change of the presence state. This may advantageously allow to avoid incorrect assignments of changes of the present state, in particular due to the deposition process 304.

[0055] In some embodiments, the presence state of the substrate is changed from “present” to “not present” or from “not present” to “present” when the absolute value of the time derivative of the first signal exceeds the first threshold and the absolute value difference of the first signal exceeds the second threshold value, dependent on theinitial presence state of the substrate. In particular, only changes in the presence state that are compatible with the initial presence state may be accepted. Exemplarily, if the initial presence state is ’’present”, only signal patterns associated with the substrate exiting the field of view of the infrared sensor are considered. If the initial presence state is “not present”, only signal patterns associated with the substrate entering the field of view of the infrared sensor may be considered.

[0056] According to some embodiments, analyzing the temporal evolution of the first signal for determining if the present state of the substrate has changed may comprise analyzing the second time derivative of the first signal. From the second time derivative, information on the change of the time derivative may be obtained. Analyzing the second time derivative may advantageously allow to distinguish heating processes, which may lead to an increasing or decreasing rate of change in the infrared signal, from substrate entering or exiting processes being associated with a fix rate of change of the infrared signal, which is particularly related to the velocity of the substrate entering or exiting the field of view of the infrared sensor.

[0057] In some embodiments, a combination of thresholds for the first signal of the first infrared sensor, the time derivative of the first signal and / or the second time derivative of the first signal may be applied to determine if the presence state of the substrate has changed. In some embodiments, the thresholds, in particular the first and the second threshold, may comprise a value range.

[0058] In some embodiments, during entering and / or exiting the field of view of the infrared sensor, the signal may be influenced by infrared emission of the substrate carrier. In particular, the emissivity of the substrate carrier may be different, particularly lower, from the emissivity of the substrate. In some embodiments, the infrared emission of the substrate carrier may lead to an additional step in the infrared signal during exiting and / or entering of the substrate.

[0059] According to some embodiments, the signal of the infrared sensor may be analyzed as a whole. In particular, the signal may show a pattern of signal increases and decreases that are characteristic for different steps in the deposition process. In particular, the substrate entering and exiting the field of view of the infrared sensor, which is associated with the substrate entering and exiting the processing position orwith a change in the presence state of the substrate, may exhibit a characteristic pattern. Exemplarily, different signal patterns may arise from the different nature of the signal change during entering and exiting, namely that the emissivity of the substrate may be considerably different from the emissivity of the chamber components present in the field of view without the substrate being present, in comparison to the deposition process, where the change of the infrared signal is caused mainly by a change of temperature.

[0060] Analyzing and recognizing patterns of the infrared signal and associating certain patterns to certain deposition steps may comprise using a trained machine learning (ML) model. In particular, the trained ML model may be implemented in the presence state determining unit.

[0061] The ML model may be trained using training data, in particular, labeled training data. In the training data, different steps of the deposition process may be labeled. In particular, changes of the presence state may be labeled. The training data may comprise test processes. The test processes may comprise deposition processes with a plurality of deposition settings, exemplarily with a plurality of temperatures or deposition times, and / or a plurality of velocities of transporting the substrate. The test processes may comprise a plurality of substrate materials and / or substrate temperatures during entering or exiting the field of view of the infrared sensor. The test processes may comprise a plurality of substrate carrier materials and geometries.

[0062] In some embodiments, the training data may comprise field deposition processes. The field deposition processes may comprise deposition processes at a plurality of sites, in particular at user sites.

[0063] In some embodiments, the trained ML model may be specific for a material of the substrate and / or a setting of the deposition process. In some embodiments, the trained ML model may be applicable to a plurality of materials of the substrate and / or to a plurality of settings of the deposition process. In some embodiments, the trained ML model may be selected based on information received via the interface of the presence state determining unit.

[0064] The training data of the trained ML model may comprise a raw signal of theinfrared signal, the time derivative of the infrared signal and / or the second time derivative of the infrared signal. In some embodiments, the training data may comprise the first signal of the first infrared sensor, the second signal of the second infrared sensor and / or the second signals of the plurality of second infrared sensors, and their respective first and second time derivatives.

[0065] In some embodiments, the training data of the trained ML model may comprise additional signals from components of the processing chamber, exemplarily from the transport apparatus such as the substrate transport system or additional sensors of the processing chamber. In some embodiments, the training data may comprise a trigger signal, particularly indicating time ranges of interest.

[0066] According to some embodiments, training the ML model with training data comprises mapping input data, in particular, based on the temporal evolution of the first signal, the second signal and / or the plurality of second signals of the plurality of second sensors, to corresponding known changes of the presence state of the substrate to provide the trained ML model.

[0067] In some embodiments, the trained ML model receives, particularly as an input, the first signal of the first infrared sensor, the second signal of the second infrared sensor and / or second signals of the plurality of second sensors and provides, as an output, information on whether the presence state of the substrate has changed. In some embodiments, the trained ML model may receive the initial presence state of the substrate and may provide the present presence state of the substrate.

[0068] According to some embodiments, the input of the trained ML model may further comprise additional signals from components of the processing chamber, exemplarily from a transport apparatus such as the substrate transport system or additional sensors of the processing chamber. In some embodiments, the input of the trained ML model may comprise a trigger signal.

[0069] According to some embodiments, the trained ML model may provide, as an output, information on the integrity state of the substrate. In particular, training the ML model with training data comprises mapping input data, in particular, based on the temporal evolution of the first signal, the second signal and / or the plurality of secondsignals of the plurality of second sensors, to a corresponding known integrity state of the substrate to provide the trained ML model.

[0070] The trained machine learning model may associate specific features in the signal of the infrared sensor with corresponding specific weights, based on a training in the training process. The machine learning model may be a one-layer model (that summarizes specific features in the signal of the infrared sensor multiplied by the respective weight) or may be a two or multi-layer model, specifically in the form of a neuronal network, as is typical in machine learning.

[0071] Methods for analyzing the first signal of the first infrared sensor may also be applied on the second signal of the second infrared sensor, and / or on the second signals of the plurality of second infrared sensors.

[0072] According to some embodiments, the presence sensor system, comprising the presence state determining and at least one infrared sensor, may be part of a processing chamber. In particular, the presence state determining unit may be a part of a deposition process control unit controlling the deposition process.

[0073] Thus, in view of the embodiments described herein, improved methods for determining a change of a presence state of a substrate in a processing chamber and improved presence sensor systems are provided, particularly for the deposition of a TFT layer. The embodiments described herein provide a reduced complexity and cost of the sensor system and allow for determining a change of a presence state of a substrate in a processing chamber without additional sensors, using sensors commonly present, exemplarily infrared temperature sensors.

[0074] While the foregoing is directed to embodiments of the disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

[0075] In particular, this written description uses examples to disclose the disclosure, including the best mode, and also to enable any person skilled in the art to practice the described subject-matter, including making and using any devices or systems and performing any incorporated methods. While various specificembodiments have been disclosed in the foregoing, mutually non-exclusive features of the embodiments described above may be combined with each other. The patentable scope is defined by the claims, and other examples are intended to be within the scope of the claims if the claims have structural elements that do not differ from the literal language of the claims, or if the claims include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

CLAIMS1. A method of determining a change of a presence state of a substrate in a processing chamber, comprising: measuring a first signal of a first infrared sensor over time, a field of view of the first infrared sensor facing towards a substrate transport path in the processing chamber; and analyzing a temporal evolution of the first signal for determining if the presence state of the substrate has changed.

2. The method of claim 1 , wherein the substrate and the processing chamber have a different emissivity.

3. The method of any of claims 1 to 2, wherein the field of view of the first infrared sensor faces towards a back side of the substrate transport path, such that an infrared emission signal of the back side of the substrate is measured when the substrate is present in the field of view.

4. The method of any of claims 1 to 3, wherein the method further comprises providing an emissivity value of the substrate to a controller.

5. The method of claim 4, further comprising determining a temperature of the substrate from the first signal of the first infrared sensor using the emissivity value of the substrate.

6. The method of any of claims 1 to 5, further comprising receiving an initial presence state of the substrate.

7. The method of any of claims 1 to 6, wherein analyzing the temporal evolution of the first signal comprises analyzing the temporal evolution of the first signal of the first infrared sensor.

8. The method of any of claims 1 to 7, wherein analyzing the temporal evolution of the first signal comprises analyzing a time derivative of the first signal.

9. The method of claim 8, wherein the absolute value of the time derivative of the first signal exceeding a first threshold and the absolute value difference of the first signal exceeding a second threshold value is associated with a change of the presence state.

10. The method of claim 9, wherein the change of the presence state is associated with a substrate exiting or a substrate entering.11 . The method of any of claims 9 to 10, wherein the presence state of the substrate is changed from “present” to “not present” or from “not present” to “present” when the absolute value of the time derivative of the first signal exceeds the first threshold and the absolute value difference of the first signal exceeds the second threshold value, dependent on the initial presence state of the substrate.

12. The method of any of claims 1 to 11 , wherein analyzing the temporal evolution of the first signal comprises using a trained machine learning, ML, model for recognizing a pattern associated with a change of the presence state of the substrate.

13. The method of claim 12, further comprising: training a ML model with training data that map input data based on the temporal evolution of the first signal of the first infrared sensor to corresponding known changes of the presence state of the substrate to provide the trained ML model.

14. The method of any of claims 12 to 13, wherein the trained ML model receives the first signal of the first infrared sensor and provides, as an output, an information on whether the presence state of the substrate has changed.

15. The method of any of claims 1 to 14, wherein analyzing the temporal evolution of the first signal comprises restricting the temporal evolution of the first signal to a time window around a predefined event.

16. The method of claim 15, wherein the predefined event comprises receiving a trigger signal from at least one of a sensor, the processing chamber and a transport apparatus.

17. The method of any of claims 1 to 16, further comprising: measuring one or more second signals of a plurality of one or more second infrared sensors over time, the field of view of the second infrared sensors facing towards the substrate transport path in the processing chamber; andanalyzing a temporal evolution of the one or more second signals for determining if the presence state of the substrate has changed.

18. The method of any of claims 1 to 17, wherein the first infrared sensor comprises a thermography apparatus, in particular, configured to obtain a spatially-resolved sensor signal.

19. A presence sensor system for a processing chamber comprising: an infrared sensor; and a presence state determining unit; wherein the presence state determining unit is configured for executing the method of any of claims 1 to 18.

20. A processing chamber comprising the presence sensor system of claim 19.

Images