Monitoring substrate properties by transmitting laser light through a ceramic layer of an electrostatic chuck

Abstract

A laser measuring system for a substrate processing system includes a substrate support including a baseplate including a bore and a ceramic layer attached to the baseplate by a bonding layer. A laser assembly includes a laser configured to transmit light through the bore in the baseplate, through the ceramic layer, and onto a back side surface of a substrate. A spectrometer is configured to receive reflected signals from the substrate through the bore. A controller is configured to determine optical path lengths of the reflected signals from the substrate and to calculate a parameter of the substrate based thereon.

Description

MONITORING SUBSTRATE PROPERTIES BY TRANSMITTING LASER LIGHT THROUGH A CERAMIC LAYER OF AN ELECTROSTATIC CHUCKCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 644,872 filed on May 9, 2024. The entire disclosure of the above application is incorporated herein by reference.FIELD

[0002] The present disclosure relates to substrate processing systems, and more particularly to systems and methods for monitoring substrate properties by transmitting laser light through a ceramic layer of an electrostatic chuck.BACKGROUND

[0003] The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

[0004] Substrate processing systems may be used to treat substrates such as semiconductor wafers. The substrate treatments may include deposition, etching, cleaning, and / or other treatments. During processing, a substrate is arranged on a substrate support in a processing chamber of the substrate processing system. Gas mixtures are introduced into the processing chamber using a gas delivery device. In some processes, radio frequency (RF) plasma may be used to initiate chemical reactions.

[0005] For processes such as etching, maintaining the temperature of the substrate at a predetermined temperature is important for process uniformity. However, etching typically involves the use of etching chemistry, high RF voltage, and / or plasma. Due to the harsh environment in the processing chamber, it is difficult to locate temperature sensors on or sufficiently close to the substrate to provide accurate substrate temperature measurements. Less accurate substrate temperature estimates can be generated based on temperature sensors located between a baseplate and a ceramiclayer of an electrostatic chuck, in coolant below the facility plate, and / or in coolant in a temperature controller in a subfab. The inconsistent temperature readings makes it challenging to accurately estimate the substrate temperature with precision to allow control of the process.SUMMARY

[0006] A laser measuring system for a substrate processing system includes a substrate support including a baseplate including a bore and a ceramic layer attached to the baseplate by a bonding layer. A laser assembly includes a laser configured to transmit light through the bore in the baseplate, through the ceramic layer, and onto a back side surface of a substrate. A spectrometer is configured to receive reflected signals from the substrate through the bore. A controller is configured to determine optical path lengths of the reflected signals from the substrate and to calculate a parameter of the substrate based thereon.

[0007] In other features, the controller is configured to determine a temperature of the substrate based on the reflected signals during processing of the substrate. Processing of the substrate includes plasma processing. The controller is configured to determine a thickness of the one or more layers of the substrate based on the reflected signals after processing of the substrate.

[0008] In other features, the laser assembly includes a coupler arranged between the laser and the baseplate, and the coupler is configured to receive light from the laser and the reflected signals from the substrate. The laser assembly includes a lens arranged between the coupler and the baseplate.

[0009] In other features, an RF generator configured to strike plasma above the substrate support. The controller is configured to calculate a temperature of the substrate while the plasma is present. The controller is configured to calculate a difference between first and second optical path lengths based on the reflected signals; calculate a thickness of a portion of the substrate based on the difference and a refractive index of the substrate; and calculate a temperature of the substrate based on the thickness.

[0010] In other features, the substrate includes a bottom substrate layer and a plurality of upper layers, and the reflected signals correspond to reflected light from a bottom side of the bottom substrate layer and a top side of the bottom substrate layer.Measurement of a temperature of the substrate occurs while etching of at least one of the upper layers is being performed.

[0011] In other features, L laser assemblies including the laser assembly, where L is an integer greater than one. The L laser assemblies measure L temperatures at L locations of the substrate, respectively. The L laser assemblies measure L thicknesses at L locations of the substrate, respectively. The laser operates in a wavelength range from 800 to 2000 nm.

[0012] In other features, the temperature is used to adjust control of a device during processing of the substrate. The temperature is used to adjust coolant temperature during processing of the substrate. The temperature is used to adjust heating of the substrate during processing of the substrate. The temperature is used to vary cooling gas flow during processing of the substrate.

[0013] A laser measuring system for a plasma processing system includes a substrate support including a baseplate including a first bore, a ceramic layer attached to the baseplate by a bonding layer and including a second bore aligned with the first bore, and a plug arranged in at least one of the first bore and the second bore. A laser assembly includes a laser configured to transmit light through the plug and onto a back side of a substrate. A spectrometer is configured to receive reflected signals from the substrate. A controller is configured to determine optical path lengths of the reflected signals from the substrate and to calculate a parameter of the substrate based thereon.

[0014] In other features, the controller is configured to determine a temperature of the substrate based on the reflected signals during processing of the substrate. Processing of the substrate includes plasma processing. The controller is configured to determine a thickness of the one or more layers of the substrate based on the reflected signals after processing of the substrate. The laser assembly includes a coupler arranged between the laser and the baseplate and configured to receive light from the laser and reflected light from the substrate. The laser assembly includes a lens arranged between the coupler and the baseplate.

[0015] In other features, an RF generator is configured to strike plasma above the substrate support. The controller is configured to calculate a temperature of the substrate while the plasma is present. The controller is configured to calculate a difference between first and second optical path lengths based on the reflected signals, calculate a thickness of a portion of the substrate based on the difference and arefractive index of the substrate, and calculate a temperature of the substrate based on the thickness.

[0016] In other features, the substrate includes a bottom substrate layer and a plurality of upper layers, and the reflected signals correspond to reflections from a bottom side of the bottom substrate layer and a top side of the bottom substrate layer.

[0017] In other features, measurement of a temperature of the substrate occurs while etching of at least one of the upper layers is being performed. L laser assemblies including the laser assembly, where L is an integer greater than one. The L laser assemblies measure L temperatures at L locations of the substrate, respectively. The L laser assemblies measure L thicknesses at L locations of the substrate, respectively. The laser operates in a wavelength range from 800 to 2000 nm.In other features, the plug is made of sapphire.

[0018] In other features, the temperature is used to adjust control of a device during processing of the substrate. The temperature is used to adjust coolant temperature during processing of the substrate. The temperature is used to adjust heating of the substrate during processing of the substrate. The temperature is used to vary cooling gas flow during processing of the substrate.

[0019] Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims, and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0021] FIG. 1 is a functional block diagram of a substrate processing system including a laser measuring system including a laser transmitting a laser beam through a ceramic layer of a substrate support according to the present disclosure;

[0022] FIGS. 2 and 3 are functional block diagrams illustrating indirect estimation of temperature of the substrate using a temperature sensor arranged on a back side surface of the ceramic layer;

[0023] FIG. 4A is a functional block diagram of a substrate processing system including a laser measuring system including a laser transmitting a laser beam through a plug arranged in a bore in a ceramic layer of a substrate support according to the present disclosure;

[0024] FIG. 4B is an enlarged view of the plug arranged in the ceramic layer of the substrate support according to the present disclosure;

[0025] FIG. 5A is a functional block diagram of a substrate processing system including a laser measuring system including a laser transmitting a laser beam directly through the ceramic layer of the substrate support according to the present disclosure;

[0026] FIG. 5B is an enlarged view the laser beam passing directly through the ceramic layer of the substrate support according to the present disclosure;

[0027] FIG. 5C is an enlarged view of the laser light being reflected by surfaces of a substrate according to the present disclosure;

[0028] FIG. 5D is a graph illustrating intensity as a function of wavelength for a signal reflected by the substrate according to the present disclosure;

[0029] FIG. 5E is a graph illustrating intensity as a function of optical path length according to the present disclosure;

[0030] FIG. 6 is a functional block diagram of an example of a multi-zone laser measuring system according to the present disclosure;

[0031] FIG. 7 is a graph illustrating measured thickness as a function of temperature for a sample substrate according to the present disclosure;

[0032] FIG. 8 illustrates transmittance of an example ceramic layer as a function of wavelength according to the present disclosure;

[0033] FIG. 9 is a flowchart of an example of a method for measuring a temperature of a substrate during substrate processing using a laser beam passing through the ceramic plate according to the present disclosure; and

[0034] FIG. 10 is a flowchart of an example of a method for measuring a thickness of a substrate before or after substrate processing using a laser beam passing through the ceramic plate according to the present disclosure.

[0035] In the drawings, reference numbers may be reused to identify similar and / or identical elements.DETAILED DESCRIPTION

[0036] Controlling the temperature of a substrate during etching is important because the etch reactions are typically temperature dependent. In other words, the etching rate varies with temperature. It is difficult to directly measure the temperature of the substrate during a plasma process due to the plasma, high plasma voltage, and / or corrosive etching chemistry.

[0037] Some substrate processing systems attempt to determine substrate temperature during substrate processing using temperature sensors that do not directly measure substrate temperature. For example, a temperature sensor may be arranged between a ceramic layer and a baseplate of an electrostatic chuck. Temperature sensors may be used to monitor the temperature of coolant in a temperature control unit (TCU) and / or in cooling lines near a bottom side of a facility plate. The temperature of the substrate can be estimated based on one or more of these temperature measurements.

[0038] However, the indirect temperature estimates are prone to errors. The substrate temperature is not known accurately during processing, which may cause instability. As a result, etching performance may be compromised, which impacts customer productivity. Without the ability to directly measure substrate temperature during the process, manufacturers and / or equipment users need to expend additional engineering effort for chamber matching and / or recipe development, which increases cost.

[0039] In other processes, calibration substrates including an array of temperature sensors are arranged in the processing chamber and some or all of the process is run. Temperature feedback from the temperature sensors located on the calibration substrates are used to calibrate the process. However, the calibration substrates are unreliable and / or the calibration substrates may not be made of the same materials as the substrates to be processed, which causes calibration errors. Calibration using this approach is expensive and time consuming.

[0040] The present disclosure relates to laser measuring systems and methods for directly monitoring substrate parameters (e.g., substrate temperature during a process and / or thicknesses of one or more substrate layers before or after processing). The laser measuring systems and methods transmit laser light through a plug arranged in a bore in a ceramic layer of an electrostatic chuck. In some examples, the plug is made of a transmissive material. The laser light is transmitted through the plug, reflected by alayer or layers of the substrate, and passes back through the plug to a spectrometer. In other examples, the laser measuring systems and methods transmit laser light directly through the ceramic layer (without using the plug).

[0041] In some examples, the substrate typically includes a bottom substrate layer such as silicon upon which additional layers (e.g., such as oxide, nitride, and / or other layers) are deposited, patterned, and / or etched. In some examples, a hard mask layer may be deposited, patterned, and used during etching of upper layers of the substate.

[0042] During processing of the substrate, the laser light is directed through the plug or the ceramic layer. Some of the laser light passing through the plug or the ceramic layer is reflected by a bottom side of the bottom substrate layer and a first optical path length is calculated. Some of the light continues and is reflected by an upper side of the bottom substrate layer and a second optical path length is calculated. The difference between the optical path lengths is determined. The thickness and refractive index of the bottom substrate layer are known (both parameters change due to variations in substrate temperature). Therefore, the temperature / thickness can be measured from the differential optical path length.

[0043] Optical path length is directly related to the substrate thickness and refractive index. In other words, optical path length is equal to a product of thickness and the refractive index of the bottom substrate layer (that is not being etched). Both the substrate thickness and the refractive index are temperature dependent. Therefore, if the refractive index and the optical path length of the bottom substrate layer are known, the thickness of the bottom substrate layer can be determined accurately. The optical path length of the bottom substrate layer is then used to determine the temperature of the bottom substrate layer and the substate.

[0044] In other examples, the substrate is processed in the processing chamber and the process ends. After a predetermined period, the temperature of the substrate equalizes with the substrate support and the temperature of the substrate is known. After the predetermined period, the laser transmits a laser beam through the ceramic layer and / or the plug and the reflected signals are received. Since temperature is known, the reflected signals are used to measure the thickness of one or more layers of the substrate.

[0045] Referring now to FIG. 1 , a substrate processing system 100 includes a processing chamber 102 including a gas distribution device 104 and a substratesupport 106. In some examples, the substrate support 106 includes an electrostatic chuck (ESC). During operation, a substrate 108 is arranged on the substrate support 106.If an ESC is used, the substrate support 106 includes a baseplate 110. In some examples, the baseplate 110 is made of a conducting material such as aluminum. The baseplate 110 supports a ceramic layer 112. A bond layer 114 (and an optional spray coating) are used to bond the ceramic layer 112 to the baseplate 1 10. The baseplate 110 may include one or more coolant channels 1 16 for flowing coolant through the baseplate 110. In some examples, an edge ring 118 is arranged around the substrate support 106 to shape the plasma.

[0046] A gas delivery system 130 includes one or more gas sources 132-1 , 132-2, ..., and 132-N, where N is an integer. The gas sources 132 supply one or more process gas mixtures. For an etching process, the process gas mixture may include including carrier gas, inert gases, etching gas, etc. For a deposition process, the process gas mixture may include including carrier gas, inert gases, deposition precursor gases, etc. The gas sources 132 are connected by flow metering devices 134-1 , 134-2, ..., and 134-N (e.g., mass flow controllers and valves) to a manifold 140. An output of the manifold 140 is fed to the gas distribution device 104. In some examples, a vapor delivery system 170 includes one or more vapor delivery sources that supply vapor to the manifold 140 or connect to the gas distribution device 104 downstream from the manifold 140. In some examples, the vapor delivery system 170 includes one or more ampoules 174, vaporizers 176, and flow metering devices 178 to controllably supply the vapor to the processing chamber.

[0047] In some examples, a temperature controller 142 is connected to heating elements 144 (e.g., thermal control elements (TCEs) or resistive heaters) arranged in the ceramic layer 112. The temperature controller 142 may be used to supply power to the heating elements 144 to control a temperature of the substrate support 106 and the substrate 108 during processing. The temperature controller 142 also operates a coolant assembly 146 that controls coolant flow through the coolant channels 116. For example, the coolant assembly 146 may include a coolant pump and coolant reservoir (not shown). The temperature controller 142 operates the coolant assembly 146 to selectively flow the coolant through the coolant channels 116 to cool the substrate support 106.

[0048] A valve 150 and a pump 152 are used to control pressure within the processing chamber 102 and / or to evacuate reactants from the processing chamber 102. A gas source 151 and a flow controller 153 can be used to supply cooling gas such as helium or other gas between the substrate 108 and a top surface of the ceramic layer 112. In some examples, the ceramic layer 112 includes one or more bores for inlet(s) and outlet(s) to supply cooling gas and one or more features such as circular seal bands and / or a pattern of mesas to create space to allow cooling gas to be supplied.

[0049] A plasma generator 154 includes a radio frequency (RF) source 156 to output RF voltage / power to a matching network 158. The matching network 158 matches the impedance of the RF source 156 to the impedance of the load including the processing chamber and plasma.

[0050] A controller 160 may be used to monitor system parameters and to control components of the substrate processing system 100 based on a recipe. One or more robots 161 may be used to deliver substrates onto, and remove substrates from, the substrate support 106. The gas distribution device 104 includes a gas plenum 210 that distributes gas from the gas delivery system 130 or vapor from the vapor delivery system 170 to gas through holes passing through an electrode 220 that is grounded.

[0051] A laser sensing assembly (LSA) 250 is optically based and is configured to transmit laser light through a plug (shown below) embedded in the ceramic layer 112 or directly through the ceramic layer 112 and onto a backside surface of the substrate 108. The laser light is reflected by the backside surface and an upper surface of the bottom substrate layer. The laser sensing assembly 250 is connected to the controller 160. During processing, the laser sensing assembly 250 can be used to determine the temperature of the substrate in response to the reflected signals and the index of refraction of the bottom substrate layer. In other examples, the temperature of the substrate equalizes with the substrate support after processing and the laser sensing assembly 250 can be used to determine the thickness of one or more layers of the substrate in response to the reflected signals. In some examples, the measured temperature is optionally used to adjust control of a device during a process. For example, the measured temperature can be used to adjust coolant temperature or flow, adjust heating of the substrate support, or to vary coolant gas flow between the ceramic layer 112 and the substrate 108.

[0052] Referring now to FIGS. 2 and 3, a baseplate 310 including cooling channels 314 is shown. In FIG. 2, a ceramic layer 318 is attached to the baseplate 310 by a bond layer 320. A spray coat 321 (FIG. 3) may be coated on the baseplate 310 between the bond layer 320 and the baseplate 310. In some examples, a substrate 324 rests features 325 (such as seal bands and / or mesas) projecting upwardly from the ceramic layer 318 to allow cooling gas such as helium to be supplied between the substrate 324 and the ceramic layer 318.

[0053] The baseplate 310 is arranged on a facility plate 330. A temperature controller 340 supplies cooling fluid to a switching / mixing manifold 348 that controls the supply of cooling fluid through a tunnel entrance 352 to the facility plate 330 and the cooling channels 314 of the baseplate 310. A temperature sensor 360 (such as a thermocouple 350) senses the temperature on a back side surface of the ceramic layer 318. Wires 363 that are connected to the thermocouple 350 pass through a bore 362 in the baseplate 310 and the facility plate 330 (and are protected from the plasma and / or etch chemistry). Temperature may also be monitored in other locations (e.g., temperature sensors 370 may be arranged in fluid lines 372 and / or in a fluid supply 378). The temperature of the substrate 324 is estimated based on one or more of the temperatures at the different locations that are monitored.

[0054] In FIG. 3, the thermocouple 350 is located on the back side of the ceramic layer 318. The substrate 324 is typically located above a top surface of the ceramic layer 318 on the features 325 that extend upwardly from the top surface of the ceramic layer 318. The features 325 allow cooling gas to flow between the substrate 324 and the ceramic layer 318.

[0055] Using this approach, substrate temperature is indirectly estimated by measuring temperature at several locations other than directly on the substrate 324 and then estimating the temperature of the substrate. For example, temperature may be monitored on the backside surface of the ceramic layer, in fluid lines 372 as the fluid lines 372 enter the facility plate 330, and / or in a fluid source 374 in the temperature controller 340. However, the sensed temperatures at these locations are different from the temperature at the substrate 324 and may or may not be directly correlated to or functionally related to the current temperature at the substrate 324. For example only, the temperature at the bottom of the substrate 324 may be 84QC. The temperature at the top of the ceramic layer may be 60QC. The temperature at the bottom of the ceramiclayer 318 may be 59QC. The temperature at the bottom of the bond layer 320 may be 50aC. The temperature at the top of the baseplate may be 482C. The temperature of the cooling fluid in the temperature controller 340 may be 40QC. It is difficult to accurately predict the temperature of the substrate 324 based on these indirect temperature measurements.

[0056] The laser measuring system according to the present disclosure uses optical coherence tomography (OCT) to measure the substrate parameter (e.g., temperature of thickness of the substrate). OCT measures optical path lengths based on laser interference. The optical path length is equal to a product of the thickness and the refractive index of the bottom substrate layer (which is not being etched). The refractive index of the bottom substrate layer is known. As a result, OCT can be used to determine the thickness and temperature of the bottom substrate layer. The optical path length of the bottom substrate layer varies with temperature and therefore the optical path length can be used to determine the temperature of the bottom substrate layer (and the rest of the substrate). Alternately, if the temperature is known, the thickness of one or more substrate layers can be determined post process after the substrate temperature equalizes.

[0057] Referring now to FIGS. 4A and 4B, a laser measuring system 410 includes a laser 412 that generates a laser beam that is output to a coupler 414 and a lens 420. Light output by the lens 420 is directed onto one end of a plug 428. In some examples, the plug 428 is made of a material having a transmissivity greater than or equal to the ceramic layer 318. In some examples, the plug 428 is made of sapphire or another suitable material that is plasma resistant and sufficiently transmissive.

[0058] The plug 428 includes a first portion 429 that passes through a bore 433 in the ceramic layer 318. An upper surface of the plug 428 faces a back side surface of the substrate 324. A second portion 431 of the plug is arranged in and bonded to the baseplate 310. Adhesives (e.g., such as the adhesive of the bonding layer or another adhesive) may be used to bond the plug 428 in the bore 433 defined in the ceramic layer 318 and / or in the baseplate.

[0059] In this example, the laser light is directed through the plug 428 and the ceramic layer. The laser light passes through the plug 428 and is incident on the back side of the bottom substrate layer of the substrate 324. Some of the light is reflected by the back side of the bottom substrate layer of the substrate 324. Some of the light passesthrough the bottom substrate layer of substrate 324 and is reflected by the top side of the bottom substrate layer of the substrate 324. Both sets of reflections pass back through the plug 428, the lens 420, and the coupler 414 and are received by a spectrometer 424 of the laser measuring system 410.

[0060] A controller 430 receives the reflected light and determines optical path lengths for the reflections. The controller 430 determines the temperature / thickness of the bottom substrate layer of the substrate based on the optical path length difference and the refractive index of the bottom substrate layer. The controller 430 determines the temperature based thereon. If the temperature is known, the same setup can be used post process to measure the thickness of one or more layers of the substrate (after the substrate temperature equalizes with the substrate support).

[0061] Referring now to FIGS. 5A and 5B, while the laser light can be transmitted through the plug 428, substrate parameter measurement can also be performed without using the plug 428 or drilling the bore 433 through the ceramic layer 318. In other words, the laser light can be transmitted directly through the ceramic layer 318. Advantages of this approach include eliminating the risk of delamination of the plug 428 from the ceramic layer 318.

[0062] In FIGS. 5A and 5B, a laser measuring system 500 includes one or more laser assemblies 510. Each of the laser assemblies 510 includes a laser 512 that generates a laser beam that is output to a coupler 514 and a lens 520. An output of the lens 520 is directed through a bore 528 in the baseplate 310 and onto a back side of the ceramic layer 318 without passing through a plug or drilling a bore through the ceramic layer 318 as in FIG. 4A. In FIG. 5B, the laser beam passes through the bore 528 and is transmitted directly through the ceramic layer 318. In some examples, the ceramic layer 318 includes a region 531 that the laser light passes through and that does not include electrode(s) for DC chucking, RF bias, or heating to allow the transmitted and reflected signals to pass.

[0063] Some of the laser light is reflected by the ceramic layer 318. Some of the light is reflected by the back side of the bottom substrate layer of the substrate 324. Some of the light passes through the bottom substrate layer of substrate 324 and is reflected by the top side of the bottom substrate layer of the substrate 324. Both sets of reflections pass back through the bore 528, the lens 520, and the coupler 514 and are received by a spectrometer 524 of the laser assembly. In some examples, additionalsets of reflected signals for layers above the bottom substrate layer can be received and used.

[0064] A controller 530 receives the reflected light and determines optical path lengths for the reflections. The controller 530 determines the temperature / thickness of the bottom substrate layer of the substrate based on the optical path length difference of the bottom substrate layer. The controller 430 determines the temperature based on thereon. If the temperature is known, the same setup can be used post process to measure the thickness of one or more layers of the substrate (after the substrate temperature equalizes with the substrate support).

[0065] Referring now to FIGS. 5C to 5E, the laser light is reflected by the bottom side and the top side of a bottom substrate layer 480 of a substrate 482 as shown in FIG. 5C. In some examples, the measurement is made while one or more upper layers 484 are being subjected to a substrate treatment such as etching, deposition, cleaning or other process that may or may not involve the use of plasma. The spectrometer 524 measures intensity of the reflected light as a function of a wavelength of the reflected light as shown in FIG. 5D. The controller performs an inverse Fast Fourier Transform (FFT) on the reflected signals to determine first and second optical path lengths of the reflected signals as shown in FIG. 5E. The controller 530 determines a difference between the optical path lengths of the reflections. The difference in the optical path lengths determines the optical path length in the bottom substrate layer of the substrate. The optical path length and the index of refraction are used to determine the thickness of the bottom substrate layer. Then the measured thickness is used to determine the temperature of the bottom substrate layer (and the substrate).

[0066] While the substrate processing systems in FIGS. 4A and 5A include one laser assembly, the substrate processing system may include more than one laser assembly to measure temperature in more than one location. In FIG. 6, the laser measuring system 550 includes L laser assemblies 560-1 , 560-2, ..., and 560-L where L is an integer greater than one. For example, a controller 50 and the laser assemblies 560-1 , 560-2, ..., and 560-L measure substrate parameters in different radial or circumferential locations or zones of the substrate to allow finer measurement or control.

[0067] Referring now to FIG. 7, the optical path length is shown for a sample silicon carbide (SiC) sample coupon. The measured thickness is linearly related to thetemperature of the substrate. The measured thickness depends on the optical path length and the refractive index of the bottom substrate layer as described above.

[0068] Referring now to FIG. 8, the transmittance of the ceramic layer is shown. As can be seen, the transmittance of the ceramic layer increases with the wavelength of the laser. In some examples, the laser that is used operates at wavelengths greater than or equal to 800 nm. In some examples, the laser that is used operates at a wavelength in a range from 1000 to 2000 nm.

[0069] Referring now to FIG. 9, a method 600 for measuring substrate temperature during a process (e.g., a plasma process) is shown. At 610, a substrate is delivered to a processing chamber and the process is started. At 614, a laser beam is transmitted directly through the ceramic layer or through the plug. At 618, reflected signals are measured, At 622, the temperature of the substrate is determined based on the reflected signals. As can be appreciated, the temperature can be measured in multiple locations or zones. At 623, the measured temperature is optionally used to a control a device during the process. For example, the measured temperature can be used to adjust coolant temperature or flow, adjust heating of the substrate support, and / or to vary coolant gas flow between the ceramic layer 1 12 and the substrate 108. At 624, the method determines whether the process is over. If false, the method returns to 614.

[0070] As discussed above, the laser measurement system can also be used as a post process to measure the thickness of one or more layers of the substrate. After processing is performed, the temperature of the substrate equalizes to the temperature of the substrate support. Once equalized, the temperature of the substrate is known. The laser measurement system transmits laser beams through the plug or the ceramic layer and reflected signals are measured. Since the temperature is known, the laser measurement system can be used to estimate the thickness of one or more layers of the substrate.

[0071] Referring now to FIG. 10, a method 700 for measuring a thickness of the substrate after processing is shown. At 710, a process is performed on the substrate in the processing chamber. At 714, the process ends. At 718, the method waits a predetermined period to allow the substrate temperature to match the substrate support. At 722, a laser beam is transmitted through the ceramic layer or the plug. At 724, the thickness of the substrate (and / or specific layers of the substrate) isdetermined based on the reflected signals. As can be appreciated, the thickness can be measured in multiple locations or zones.

[0072] The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. Further, although each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the disclosure can be implemented in and / or combined with features of any of the other embodiments, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with one another remain within the scope of this disclosure.

[0073] Spatial and functional relationships between elements (for example, between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including “connected,” “engaged,” “coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and “disposed.” Unless explicitly described as being “direct,” when a relationship between first and second elements is described in the above disclosure, that relationship can be a direct relationship where no other intervening elements are present between the first and second elements, but can also be an indirect relationship where one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”

[0074] In some implementations, a controller is part of a system, which may be part of the above-described examples. Such systems can comprise semiconductor processing equipment, including a processing tool or tools, chamber or chambers, a platform, or platforms for processing, and / or specific processing components (a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controllingtheir operation before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as the “controller,” which may control various components or subparts of the system or systems. The controller, depending on the processing requirements and / or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and / or load locks connected to or interfaced with a specific system.

[0075] Broadly speaking, the controller may be defined as electronics having various integrated circuits, logic, non-transitory memory, and / or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some embodiments, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies of a wafer.

[0076] The controller, in some implementations, may be a part of or coupled to a computer that is integrated with the system, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be in the “cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process. In some examples, a remote computer (e.g., a server) can provide process recipes to a system over anetwork, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and / or settings, which are then communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control. Thus, as described above, the controller may be distributed, such as by comprising one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber.

[0077] Without limitation, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and / or manufacturing of semiconductor wafers.

[0078] As noted above, depending on the process step or steps to be performed by the tool, the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and / or load ports in a semiconductor manufacturing factory.

Claims

CLAIMSWhat is claimed is:1 . A laser measuring system for a substrate processing system, comprising: a substrate support including: a baseplate including a bore; and a ceramic layer attached to the baseplate by a bonding layer; a laser assembly including a laser configured to transmit light through the bore in the baseplate, through the ceramic layer, and onto a back side surface of a substrate; a spectrometer configured to receive reflected signals from the substrate through the bore; and a controller configured to determine optical path lengths of the reflected signals from the substrate and to calculate a parameter of the substrate based thereon.

2. The laser measuring system of claim 1 , wherein the controller is configured to determine a temperature of the substrate based on the reflected signals during processing of the substrate.

3. The laser measuring system of claim 2, wherein processing of the substrate includes plasma processing.

4. The laser measuring system of claim 1 , wherein the controller is configured to determine a thickness of the one or more layers of the substrate based on the reflected signals after processing of the substrate.

5. The laser measuring system of claim 1 , wherein: the laser assembly includes a coupler arranged between the laser and the baseplate, and the coupler is configured to receive light from the laser and the reflected signals from the substrate.

6. The laser measuring system of claim 5, wherein the laser assembly includes a lens arranged between the coupler and the baseplate.

7. The laser measuring system of claim 1 , further comprising an RF generator configured to strike plasma above the substrate support.

8. The laser measuring system of claim 7, wherein the controller is configured to calculate a temperature of the substrate while the plasma is present.

9. The laser measuring system of claim 1 , wherein the controller is configured to: calculate a difference between first and second optical path lengths based on the reflected signals; calculate a thickness of a portion of the substrate based on the difference and a refractive index of the substrate; and calculate a temperature of the substrate based on the thickness.

10. The laser measuring system of claim 1 , wherein: the substrate includes a bottom substrate layer and a plurality of upper layers, and the reflected signals correspond to reflected light from a bottom side of the bottom substrate layer and a top side of the bottom substrate layer.11 . The laser measuring system of claim 10, wherein measurement of a temperature of the substrate occurs while etching of at least one of the upper layers is being performed.

12. The laser measuring system of claim 1 , further comprising L laser assemblies including the laser assembly, where L is an integer greater than one.

13. The laser measuring system of claim 12, wherein the L laser assemblies measure L temperatures at L locations of the substrate, respectively.

14. The laser measuring system of claim 12, wherein the L laser assemblies measure L thicknesses at L locations of the substrate, respectively.

15. The laser measuring system of claim 1 , wherein the laser operates in a wavelength range from 800 to 2000 nm.

16. The laser measuring system of claim 2, wherein the temperature is used to adjust control of a device during processing of the substrate.

17. The laser measuring system of claim 2, wherein the temperature is used to adjust coolant temperature during processing of the substrate.

18. The laser measuring system of claim 2, wherein the temperature is used to adjust heating of the substrate during processing of the substrate.

19. The laser measuring system of claim 2, wherein the temperature is used to vary cooling gas flow during processing of the substrate.

20. A laser measuring system for a plasma processing system, comprising: a substrate support including: a baseplate including a first bore; a ceramic layer attached to the baseplate by a bonding layer and including a second bore aligned with the first bore; and a plug arranged in at least one of the first bore and the second bore; a laser assembly including a laser configured to transmit light through the plug and onto a back side of a substrate; a spectrometer configured to receive reflected signals from the substrate; and a controller configured to determine optical path lengths of the reflected signals from the substrate and to calculate a parameter of the substrate based thereon.21 . The laser measuring system of claim 20, wherein the controller is configured to determine a temperature of the substrate based on the reflected signals during processing of the substrate.

22. The laser measuring system of claim 21 , wherein processing of the substrate includes plasma processing.

23. The laser measuring system of claim 20, wherein the controller is configured to determine a thickness of the one or more layers of the substrate based on the reflected signals after processing of the substrate.

24. The laser measuring system of claim 20, wherein the laser assembly includes a coupler arranged between the laser and the baseplate and configured to receive light from the laser and reflected light from the substrate.

25. The laser measuring system of claim 24, wherein the laser assembly includes a lens arranged between the coupler and the baseplate.

26. The laser measuring system of claim 20, further comprising an RF generator configured to strike plasma above the substrate support.

27. The laser measuring system of claim 26, wherein the controller is configured to calculate a temperature of the substrate while the plasma is present.

28. The laser measuring system of claim 26, wherein the controller is configured to: calculate a difference between first and second optical path lengths based on the reflected signals; calculate a thickness of a portion of the substrate based on the difference and a refractive index of the substrate; and calculate a temperature of the substrate based on the thickness.

29. The laser measuring system of claim 20, wherein: the substrate includes a bottom substrate layer and a plurality of upper layers, and the reflected signals correspond to reflections from a bottom side of the bottom substrate layer and a top side of the bottom substrate layer.

30. The laser measuring system of claim 29, wherein measurement of a temperature of the substrate occurs while etching of at least one of the upper layers is being performed.

31. The laser measuring system of claim 20, further comprising L laser assemblies including the laser assembly, where L is an integer greater than one.

32. The laser measuring system of claim 31 , wherein the L laser assemblies measure L temperatures at L locations of the substrate, respectively.

33. The laser measuring system of claim 31 , wherein the L laser assemblies measure L thicknesses at L locations of the substrate, respectively.

34. The laser measuring system of claim 20, wherein the laser operates in a wavelength range from 800 to 2000 nm.

35. The laser measuring system of claim 20, wherein the plug is made of sapphire.

36. The laser measuring system of claim 21 , wherein the temperature is used to adjust control of a device during processing of the substrate.

37. The laser measuring system of claim 21 , wherein the temperature is used to adjust coolant temperature during processing of the substrate.

38. The laser measuring system of claim 21 , wherein the temperature is used to adjust heating of the substrate during processing of the substrate.

39. The laser measuring system of claim 21 , wherein the temperature is used to vary cooling gas flow during processing of the substrate.

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