Semiconductor processing chamber and method of sensing temperature suitable for use in semiconductor processing chamber

Abstract

This document describes a method and apparatus for determining the temperature of a substrate within a semiconductor processing chamber. The method and apparatus utilize an etalon assembly and heterodyne effects to determine a first temperature of the substrate. The first temperature of the substrate is determined without physical contact with the substrate. A separate temperature sensor also measures a second temperature of the substrate and / or a substrate support at a similar location. The first and second temperatures are used to calibrate one of the temperature sensors disposed within the substrate support, to model a process performed within the semiconductor processing chamber, or to adjust process parameters of the process performed within the semiconductor processing chamber.

Description

[Technical Field]

[0001] The embodiments of this disclosure are generally related to temperature measurement in a semiconductor processing chamber, and more specifically to non-contact temperature measurement by heterodyne coherent radiation between two standard objects in or associated with the processing chamber. [Previous Technology]

[0002] Temperature is a critical parameter in semiconductor processing. Measuring the temperature of a selected object at various locations within the processing chamber and at various processing stages can be challenging. For example, in-situ temperature measurement of semiconductor substrates presents significant challenges to conventional measurement techniques.

[0003] Current pyrometers estimate temperature by detecting thermal radiation. However, while current pyrometers avoid the risks of surface contact, they may be limited to high temperatures (e.g., >380°C). The accuracy of current pyrometers may be limited due to variability in emissivity (e.g., variability in the emissivity of surface patterns). Many novel cryogenic processes with complex film stacks exceed the limits of accurate and repeatable radiation pyrometers.

[0004] When used in processes involving plasma (such as plasma etching or plasma deposition), pyrometers become further limited. Plasma interferes with pyrometer temperature measurements by introducing noise that is difficult to filter out from pyrometer measurements, as well as additional light. In the absence of variations in emissivity or noise from radiation sources within the processing chamber, contact temperature sensors provide more direct temperature measurements. However, contact temperature sensors have limitations in response time and accuracy, and often measure the temperature of substrate supports adjacent to the substrate rather than the substrate itself.

[0005] Therefore, this technology requires improved methods and systems for temperature measurement. [Summary of the Invention]

[0006] This disclosure relates to apparatus and methods for measuring temperature within a process chamber. In one embodiment, a method suitable for sensing temperature in a semiconductor processing chamber is described. The method includes passing a first light beam through a first etalon and passing the first light beam through a substrate disposed in the processing chamber. The substrate provides a second etalon. After passing a reflected second light beam through the first and second etalons, the reflected second light beam and the transmitted second light beam are generated from the first light beam. An interference pattern from either the reflected second light beam or the transmitted second light beam determines a fringe spacing. The temperature of the substrate is determined based on the fringe spacing.

[0007] In another embodiment, a method suitable for sensing temperature in a semiconductor processing chamber is described. The method includes passing a first light beam through a first etalon and passing the first light beam through a substrate disposed in the processing chamber. The substrate provides a second etalon. One of the first or second etalon generates a reflected second light beam and a transmitted second light beam from the first light beam. The first and second etalons form an etalon assembly. An interference pattern generated within one of the reflected or transmitted second light beams from the etalon assembly determines a fringe spacing. The temperature of the substrate is determined based on the fringe spacing. The temperature is provided to a controller of the processing chamber before performing one or more of the following: calibrating a temperature sensor within the processing chamber using the temperature; applying a temperature offset to one or more measurements of the temperature sensor; adjusting a model of a process performed in the processing chamber; and adjusting process parameters of the process performed in the processing chamber.

[0008] In another embodiment, a method for calibrating temperature measurements within a processing chamber is described. The method includes performing a process operation on a reference substrate within the processing chamber. Simultaneously with performing the process operation, a first temperature of a substrate disposed within the processing chamber is measured using a first etalon assembly. Measuring the first temperature of the substrate includes passing a first light beam through a first etalon and a substrate forming a second etalon, intersecting the first light beam with the substrate, splitting the first light beam into a reflected second beam and a transmitted second beam using either the first or second etalon, collecting either the reflected or transmitted second beam using a radiation measurement device, and analyzing the reflected or transmitted second beam to determine the first temperature of the substrate. The method further includes using a first temperature sensor to measure a second temperature of the substrate or a substrate support on which the substrate is disposed, transmitting the first and second temperatures to a controller, and calibrating a model within the controller using the first and second temperatures.

Implementation Method

[0026] Embodiments of the present invention generally relate to temperature measurement and calibration in a semiconductor processing chamber, and more specifically to non-contact temperature measurement by heterodyne radiation between two etalon objects within or associated with the processing chamber. In some embodiments, one or both of the two etalon objects are semiconductor substrates (e.g., silicon substrates). In other instances, one or both of the substrates may be made of other materials. In some embodiments, the two etalon objects include a reference substrate and a sample substrate. In some embodiments, the two etalon objects are at least partially transparent to radiation having wavelengths between about 400 nm and about 2000 nm (e.g., about 1000 nm to about 1700 nm). In some embodiments, each of the two etalon objects has a substantially uniform body thickness (i.e., a deviation of no more than about 10%). In some embodiments, the two etalon objects are closely matched in body thickness, optical thickness, refractive index, and / or relative orientation (differences between about 1% and about 10%).

[0027] One of the many potential advantages of embodiments of this disclosure is that in-situ etalon object (e.g., substrate such as a semiconductor wafer) temperature measurements can be performed with high resolution over a wide temperature range (e.g., from about -200°C to about 700°C). Another advantage includes enabling direct temperature measurements without relying on emissivity or heat transfer problems that may be caused by methods near the substrate. The temperature measurements disclosed herein are minimally or unaffected by background or stray radiation. Another advantage includes allowing for more accurate temperature data for chamber design, testing, and / or maintenance. More accurate testing may be particularly important in systems with high background radiation and in systems equipped to generate plasma therein. Another advantage includes achieving increased temperature uniformity on the substrate during processing. For example, the temperature measurements disclosed herein are minimally or unaffected by emissivity variations in the sample substrate and provide rapid and accurate local temperature feedback that allows rotation of the process knob to achieve improved temperature and process uniformity. Another advantage includes improved chamber matching and / or improved temperature control during processing. Embodiments of this disclosure may thus be useful in the field of materials handling, where tighter process temperature control enables the manufacture of advanced (i.e., smaller node) components and / or the realization of high-volume manufacturing.

[0028] In relation to the technology described herein, substrates (such as wafers) used in semiconductor processing are typically made of silicon. As mentioned above, substrates made of other materials may be used. The substrate may be generally shaped as a flat disk. The two flat surfaces of the disk (sometimes referred to as "front" and "back", "top" and "bottom", or "first" and "second") may be generally parallel. In other words, the two surfaces of the substrate may form an etalon. As illustrated in Figure 1, the etalon 100 is an optical element in which incident radiation I (e.g., infrared radiation) bounces back and forth between the two surfaces S1 and S2. The incident radiation I may encounter the first surface S1 at an angle of incidence α. The radiation may leave the etalon 100 as transmitted radiation T and / or reflected radiation R. Due to the high refractive index of the silicon semiconductor substrate, there is significant reflection between the two surfaces. At each reflection, there is a small energy loss due to transmission. For coherent radiation at a specific wavelength, the total transmitted power of the transmitted radiation T and the total reflected power of the reflected radiation R are sensitive functions of the optical thickness (the product of the refractive index and the solid thickness) of 100. For example, the transmitted power may be high for optical thicknesses corresponding to integer multiples of the incident wavelength, while it may be low for half-integer multiples of the incident wavelength.

[0029] It should be understood that heterodyne techniques can be used in semiconductor processing involving a variety of etalon objects and materials. When the etalon object is a silicon semiconductor substrate, a radiation source can be selected to generate coherent radiation over a broad wavelength spectrum from about 400 nm to about 2000 nm (e.g., about 1100 nm to about 1700 nm). Materials such as gallium arsenide, germanium, or sapphire, as well as other materials, can be used as etalon objects in the semiconductor processing environment. In these cases, the wavelength range can be adjusted depending on the transparency window of the specific object and material.

[0030] Figure 2 illustrates the relationship between transmittance and wavelength for a standard thickness (i.e., 0.775 mm) silicon substrate at room temperature without absorption. It can be seen that, depending on the wavelength and the optical thickness of the substrate, reflection and transmission either constructively interfere or destructively interfere. As illustrated, a fringe spacing of 0.27 nm 115 (e.g., the distance between adjacent interference patterns (such as peaks or troughs)) is often too narrow to be resolved by spectrometers typically integrated into semiconductor tools. For example, a common spectrometer has a resolution of only 1.9 nm.

[0031] Figure 3 illustrates a pair of etalon objects 202 and 204 aligned along optical axis 206. Etalon objects 202 and 204 may be silicon or other suitable substrates. As illustrated, incident radiation I (e.g., infrared radiation) encounters etalon object 202, bounces between its two surfaces, and appears as transmitted radiation t. Transmitted radiation t becomes the incident radiation of the second etalon object 204, bounces between its two surfaces, and appears as transmitted radiation T or reflected radiation r. If the two etalons are closely matched (with a difference between about 1% and about 10%), the radiation produces heterogeneity (bouncing together) between the etalons. The two etalons are closely matched by controlling one or more of the refractive index, solid thickness, optical thickness, relative orientation, and / or incident angle. As described herein, the two etalons are matched such that the optical thicknesses of the two etalons differ from each other by about 10%. The optical thickness TOptic is derived from the combination of the refractive index RI, the solid thickness Tphysical, and the propagation angle θ within the etalon, such that TOptic = RI * Tphysical * cos(ɵ). Therefore, any of the refractive index, solid thickness, and / or propagation angle can be varied to match the optical thickness of each etalon to a difference within approximately 10%.

[0032] Figure 4 illustrates a graph 210 showing the transmittance versus wavelength of a pair of standard thickness (i.e., 0.775 mm) silicon substrates (such as those shown in Figure 3). In Figure 4, the reference substrate is maintained at 25°C, while the sample is at 100°C. The reference substrate may be the second etalon object 204 in Figure 3. Graph 210 illustrates the heterodyne spectrum of the transmitted radiation T. This heterodyne spectrum has a fringe spacing that is generally wider than the fringe spacing in graph 110. For example, the fringe spacing 215 between selected adjacent interference peaks (near-end wavelength = 1500 nm) is approximately 80 nm. Note that, unlike graph 110, the fringe spacing in graph 210 varies with wavelength. A similar heterodyne spectrum can be obtained using the transmitted radiation T. This heterodyne spectrum can resemble a wavy pattern. Two heterodynes form an overlapping intensity pattern, similar to the intensity pattern produced by a wavy interferometer. Similar to the intensity pattern of a ripple interferometer, the intensity pattern generated using an etalon assembly varies with one or more of the properties (such as refractive index) of one or both of the etalons within the etalon assembly.

[0033] Figure 5 illustrates another relationship 310 between transmittance and wavelength for a pair of silicon substrates of standard thickness. In Figure 5, the reference substrate is maintained at 25°C, while the sample is at 240°C. Figure 310 illustrates a fringe spacing heterodyne spectrum with a fringe spacing that is generally much wider than that in Figure 110 but significantly narrower than that in Figure 210. For example, the fringe spacing 315 between selected adjacent interference troughs (near-end wavelength = 1500 nm) is approximately 20 nm. The heterodyne spectrum in Figure 5 can be similarly determined using either transmitted radiation T or reflected radiation r.

[0034] It should be understood that the concept and technique regarding fringe spacing can be similarly applied to interferometric pattern period counting. For example, in Figure 4, the interferometric pattern exhibits approximately 3.25 periods in the wavelength range between 1300 nm and 1500 nm. Due to the narrower fringe spacing in Figure 5, the interferometric pattern exhibits approximately 10 periods in the same wavelength range. Therefore, period counting can replace fringe spacing. Period counting can be beneficial under various operating conditions (e.g., high sample temperatures).

[0035] Similarly, it should be understood that the concepts and techniques regarding fringe spacing can be similarly applied to phase changes in interference patterns. For example, in Figure 4, the interference pattern exhibits a phase of approximately pi / 2 at a wavelength of approximately 1400 nm. In Figure 5, at the same wavelength, the interference pattern exhibits a phase of approximately -pi / 2. By gradually changing the temperature of the reference substrate from 100°C (as in Figure 4) to 240°C (as in Figure 5), it can be seen that the phase of the interference pattern gradually changes at the selected wavelength. Therefore, the phase change with respect to temperature can replace the fringe spacing. Monitoring the phase change can be beneficial under various operating conditions (e.g., high and low sample temperatures). For example, the substrate temperature can be substantially linearly correlated with the phase of the fringe pattern. This relationship can be established via the thermo-optic coefficient. In many cases, the phase change can be measured more accurately and / or more efficiently than the fringe spacing.

[0036] In some embodiments, the phase of the interference pattern can be monitored at a selected wavelength. The selected wavelength is a wavelength that is transmissive to the substrate material. For example, a selected wavelength for a silicon substrate could be 1400 nm. The phase change at the selected wavelength can be used to infer temperature changes. For rapidly changing temperature conditions, monitoring the phase change can improve the accuracy of temperature measurement. The phase change can be monitored in addition to, or instead of, measuring the fringe spacing and / or phase change.

[0037] As previously discussed, heterogeneity occurs when etalons are closely matched. For substantially parallel etalons with substantially the same body thickness (difference less than about 10%), heterogeneity occurs when the refractive indices of the etalons are closely matched (difference less than about 10%). The refractive index of a typical etalon object (e.g., a silicon substrate) associated with a processing chamber varies with temperature. Therefore, for substantially parallel etalon objects with substantially the same body thickness, the degree of heterogeneity (as indicated by the fringe spacing) varies with temperature. One of the etalon objects (referred to as the "reference" etalon object) can be maintained at a reference temperature. The other etalon object can be referred to as the "sample" etalon object. Therefore, the fringe spacing can be used to calculate the difference in refractive index between the reference etalon object and the sample etalon object. The refractive index can then be used to infer the temperature of the sample etalon object. It should be understood that the known variations in the relative angle of incidence and / or solid thickness between the reference etalon and the sample etalon have been incorporated into the calculation of the refractive index and / or inferred temperature of the sample etalon.

[0038] In some embodiments, the reference etalon may be made of a different material than the sample etalon object. In some embodiments, the reference etalon object may be made of a material having a refractive index that does not change significantly with temperature. In these embodiments, the refractive index of the reference etalon object can be known and / or estimated without requiring a specific maintenance reference temperature.

[0039] In some embodiments, the relationship between refractive index and temperature can be estimated or modeled. In some embodiments, the relationship between refractive index and temperature can be obtained via calibration. In some embodiments, a graph of the thermo-optic coefficient (i.e., the change of refractive index with temperature, dn / dT) can be used to estimate the refractive index over a given temperature range. Figure 6 illustrates the relationship between the thermo-optic coefficient and temperature for a silicon semiconductor substrate from room temperature to approximately 300°C. Note that the refractive index on the vertical axis of Figure 6 gradually changes with large temperature variations along the horizontal axis. Similar graphs of the thermo-optic coefficient can be plotted for other temperature ranges (e.g., from low temperatures to approximately 600°C, such as from approximately -200°C to approximately 600°C).

[0040] The thermo-optic coefficient can also take into account the thermal expansion of the silicon semiconductor substrate. The thermal expansion of the silicon semiconductor substrate can be incorporated into a single optical thickness value, making the optical thickness value dependent on both thermal expansion and the thermo-optic coefficient. The optical thickness value related to a specific temperature value is determined in a way that takes into account changes in the refractive index of the material and changes in substrate thickness caused by thermal expansion. When the temperature of the substrate / etalon changes, the refractive index and solid thickness of the substrate / etalon will change. This will affect the stripe spacing with respect to the relevant temperature. However, in the embodiments described herein, changes in the optical thickness value, as described herein, are more affected by changes in refractive index than changes in solid thickness. The refractive index of the material is related to the thermo-optic coefficient of the substrate material. The thermo-optic coefficient makes changes in the refractive index of the material related to changes in temperature. The thermo-optic coefficient can be determined empirically for a desired temperature range.

[0041] Figure 7 illustrates a schematic diagram of a first process chamber 700. The first process chamber 700 is configured to process a substrate, such as a semiconductor substrate, therein. The first process chamber 700 includes a chamber body 702, a chamber cover 704 disposed on top of the chamber body 702, a standard etalon assembly 708 disposed on top of the chamber cover 704, and a substrate support 710 disposed within the chamber body 702. The chamber body 702 and the chamber cover 704 form a process volume 728 therein. A substrate 725 (such as a semiconductor substrate) is disposed on top of the substrate support 710 within the process volume 728, and the standard etalon assembly 708 is configured to measure the temperature of the substrate 725.

[0042] The first process chamber 700 is configured to perform plasma processes, such as plasma etching, ion implantation, plasma deposition, or other plasma processes, on a substrate 725 disposed within a process volume 728. Plasma 726 may be formed within the process volume 728 between the substrate support 710 and the chamber cover 704. One or more induction coils 706 may be disposed above the chamber cover 704. The one or more induction coils 706 may be connected to a power supply 752. The power supply 752 may be an alternating current (AC) power supply or a radio frequency (RF) power supply. In some embodiments, the first process chamber 700 includes an inductively coupled plasma source (ICP), a capacitively coupled plasma source (CCP), and / or one or more other distal plasma sources.

[0043] One or more process gas sources 734 are fluidly coupled to the process volume 728 via one or more gas inlets 736. The process gas sources 734 may supply one or more process gases to the process volume 728. The process gases may include deposition precursors, inert gases, carrier gases, cleaning gases, etchant gases, or combinations thereof. One or more process gases introduced by the process gas sources 734 may be removed using a discharge pump 740. The discharge pump 740 is in fluid communication with the process volume 728 via a discharge opening 738. The discharge opening 738 is formed as part of the chamber body 702.

[0044] In one example, the substrate support 710 includes a substrate base 712, a shaft 716, an actuator 718, and a power supply 720. The substrate base 712 includes a support surface 714. The support surface 714 is configured to support a substrate 725. Depending on the situation, one or more temperature sensors 722, 724, such as a first temperature sensor 722 and a second temperature sensor 724, are disposed within the substrate base 712. The first temperature sensor 722 is disposed in the central portion of the support surface 714 to measure the temperature of the central portion of the substrate 725 and / or the central portion of the substrate support 710 adjacent to the substrate 725. The second temperature sensor 724 is disposed radially outward from the first temperature sensor 722 on the support surface 714. The second temperature sensor 724 is configured to measure the edge temperature of the substrate 725 and / or the temperature of the substrate support 710 adjacent to the edge of the substrate 725.

[0045] A shaft 716 is connected to the substrate base 712 and extends through the chamber body 702. The shaft 716 is connected to one or more actuators 718. The actuators 718 are configured to rotate and / or raise / lower the substrate support 710. A power supply 720 is coupled to one or more resistive heaters (not shown) disposed in the substrate base 712. These resistive heaters are used to control the temperature of the substrate base 712 and the substrate 725 disposed thereon. The power supply 720 may also apply a voltage difference to the support surface 714. Temperature sensors 722, 724 may be coupled to the power supply 720 or a multimeter (not shown).

[0046] The etalon assembly 708 includes a reference etalon 762, a light source 744, a collimator 756 disposed between the light source 744 and the reference etalon 762, a radiation measurement device 746, and a spectrometer 748. The reference etalon 762 and the collimator 756 are housed within the assembly body 758. The assembly body 758 prevents external light and radiation from entering the etalon assembly 708 and serves as an outer casing for the etalon assembly 708. The assembly body 758 further serves to hold the reference etalon 762 and the collimator 756 in place during use of the etalon assembly 708.

[0047] A first beam 732 is generated by a light source 744 and passes through one or more waveguides 750. The waveguides 750 may be optical fibers or optical tubes. The waveguides 750 are configured to transmit the first beam 732 from the light source 744 to the collimator 756 before it is subsequently transmitted to the reference etalon 762. The first beam 732 is a broadband beam and can produce a spectrum over a large wavelength range, such as a wavelength range from about 400 nm to about 2000 nm, such as about 400 nm to about 1400 nm, such as about 400 nm to about 800 nm. The broadband beam is a white beam and is configured to contain light from a broadband wavelength range. The first beam 732 is configured to pass through the collimator 756 and the reference etalon 762. After passing through the reference etalon 762, the first beam 732 is transmitted to the beam splitter 751. The beam splitter 751 is configured to transfer a first beam 732 from a reference etalon 762 to a process volume 728 via an opening 730 within the chamber cover 704 or the chamber body 702. A second collimator (such as a second collimator 757) is disposed within the opening 730 and can be optically coupled to the beam splitter 751. The second collimator 757 is configured to collimate the light as it travels into the process volume 728. The opening 730 may be further configured to allow process gases to be introduced into the process volume 728. Process gases may be introduced into the internal volume of the etalon assembly 708 via a second process gas source 742. The second process gas source 742 may introduce one or more process gases or inert gases into the assembly body 758 of the etalon assembly 708. One or more process gases may then flow into the process volume 728 via the opening 730.

[0048] In some embodiments, at least a portion of the opening 730 is covered by a second collimator 757. In some embodiments, the opening 730 is completely blocked by a window or the second collimator 757. The window separates the process volume 728 from the volume inside the component body 758 and may help maintain a constant temperature for the reference etalon 762.

[0049] A reference standard 762 is held in place using a standard etalon housing 760. The standard etalon housing 760 is configured to hold one or more reference standards in place. In the example of Figure 7, reference standard 762, second reference standard 764, and third reference standard 766 are shown. In this embodiment, reference standard 762 may be referred to as the first reference standard. Each of reference standard 762, second reference standard 764, and third reference standard 766 is housed within the standard etalon housing 760. The standard etalon housing 760 is configured to reposition the standard relative to the beam such that a selected of reference standards 762, 764, and 766 can be moved into the path of the first beam 732. As shown in Figure 7, reference standard 762 is housed within the path of the first beam 732. In some embodiments, the second reference standard 764 and the third reference standard 766 may be alternative reference standards or alternatives to the first standard. The etalon housing 760 can be configured to rotate about an axis to switch which of the reference etalons 762, 764, and 766 is incident on the first beam 732. For example, the etalon housing 760 can be coupled to a stepper or servo motor that rotates the housing 760 to selectively move one of the etalons into the beam path. The etalon housing 760 may alternatively include more or fewer reference etalons, such as only the first reference etalon 762, or only the first reference etalon 762 and the second reference etalon 764, or four or more reference etalons.

[0050] Each of the reference etalons 762, 764, and 766 has a different thickness and / or a different refractive index. The different thicknesses and / or refractive indices allow the reference etalons 762, 764, and 766 to be selected to match at least one of the refractive index and / or thickness of the substrate 725. The thickness of the reference etalon into which the first beam 732 is incident is varied by selecting one of the reference etalons 762, 764, and 766 having a desired thickness. In some embodiments, the thicknesses of the reference etalons 762, 764, and 766 within the first beam 732 are selected to match the thickness of the substrate 725 to a difference of less than about 10%, such as a difference of less than about 15 μm, such as a difference of less than about 10 μm. A close match between the thickness and / or refractive index of the reference etalons 762, 764, and 766 and the thickness of the substrate 725 achieves heterodyne of the first beam 732. In some embodiments, reference etalons 762, 764, and 766 can be manually selected by replacing one of the reference etalons from the etalon housing 760 with another reference etalon having a thickness and / or refractive index that matches that of the substrate 725.

[0051] A temperature control unit 761 is used to maintain each of the reference etalons 762, 764, and 766 at a predetermined temperature. The temperature control unit 761 is coupled to the etalon assembly 708, such as being disposed around the assembly body 758. The temperature control unit 761 is configured to maintain the predetermined temperature at least for the etalons into which the light beam is incident. For example, the temperature control unit 761 cools and / or heats the reference etalons. The temperature control unit 761 may use one or more coolant channels, a fan, one or more resistive heaters, or a combination thereof to control the temperature of the reference etalons. Maintaining the controlled temperature of the reference etalons 762, 764, and 766 enables the etalon assembly 708 to accurately measure the temperature of the substrate 725 by allowing the temperatures of the reference etalons 762, 764, and 766 to remain constant and removing the reference etalon temperature as a variable that may introduce errors.

[0052] The end of waveguide 750 is held in place by waveguide sleeve 754, which is configured to introduce the first beam 732 into the assembly body 758. Waveguide sleeve 754 is a rigid sleeve, such as a metallic or thermoplastic sleeve, configured to hold the end of waveguide 750 in place adjacent to collimator 756 and reference etalon 762. Waveguide sleeve 754 has a stiffness that limits the bending outer diameter of waveguide 750 to greater than about 15 mm, such as greater than about 18 mm, such as greater than about 20 mm. It has been demonstrated that using a rigid waveguide sleeve 754 improves the consistency of optical measurements of the etalon assembly 708.

[0053] The radiation measurement device 746 is configured to measure one or more second beams 731. The second beams 731 may be reflected or transmitted second beams. The second beams 731 are generated from the first beam 732 after it has passed through / reflected from the substrate 725. The substrate 725 acts as a second etalon. In some embodiments, the substrate 725 may be referred to as a sample etalon or sample substrate. When the first beam 732 intersects the substrate 725, the first beam 732 splits into a transmitted second beam and a reflected second beam. The first beam 732 may intersect the substrate 725 at a radial position similar to the radial position of one of the temperature sensors 722, 724. As shown in Figure 7, the first beam 732 intersects the substrate 725 at a radial position similar to that of the first temperature sensor 722.

[0054] The second beam 731 depicted in Figure 7 is a reflected second beam and returns to the component body 758 through the process volume 728. The second beam 731 is then collected in a beam splitter 751 and delivered to a radiation measurement device 746. The beam splitter 751 includes at least three openings. After passing through a reference etalon 762, a first opening of the beam splitter 751 collects the first beam 732. After returning through a second collimator, a second opening of the beam splitter 751 collects the second beam 731. A third opening of the beam splitter 751 is optically coupled to the radiation measurement device 746. The third opening of the beam splitter 751 is configured to deliver one or a combination of the first beam 732 and the second beam 731 to the radiation measurement device 746.

[0055] The second beam 731 delivered to the radiation measurement device 746 is measured and analyzed to determine the intensity and wavelength of the light delivered to the radiation measurement device 746. The radiation measurement device 746 may be a spectrometer or a spectrometer array. The radiation measurement device 746 is capable of measuring the heterodyne period of radiation. The method described herein enables the use of a radiation measurement device 746 with higher resolution. Using a radiation measurement device 746 with higher resolution reduces the cost of measuring fringe spacing as described herein. The radiation measurement device 746 may be capable of individually detecting, identifying, and / or measuring radiation from one or more optical waveguides 750. For example, the radiation measurement device 746 may include one or more selection devices (e.g., switches, optical slicers, or multibeam splitters) capable of selecting among optical waveguides 750. The radiation measurement device 746 may sequentially select one or more of the optical waveguides 750 for measurement.

[0056] Data collected by the radiation measurement device 746 is transmitted to the spectrometer 748. The spectrometer 748 may be able to receive data from the radiation measurement device 746. In some embodiments, the spectrometer 748 may be able to individually identify and / or analyze spectral data from one or more optical waveguides 750. The spectrometer 748 may receive, process, store, and / or analyze data from one or more elements of the etalon assembly 708 to identify spectral interference fringe spacings (such as fringe spacing 215 in Figure 4 and / or fringe spacing 315 in Figure 5) to calculate one or more optical thicknesses of the substrate 725, and / or infer one or more temperature measurements of the substrate 725.

[0057] It should be understood that, by virtue of the benefits of this disclosure, the above configuration can be reconfigured to operate in a transmission mode. The transmission mode may include the use of a transmitted second beam instead of a reflected second beam. This embodiment may be advantageous for measuring the temperature of non-reflective substrates or substrates oriented in a manner where reflected radiation is difficult to receive. Illustrative transmission modes are provided in Figures 9B and 9C.

[0058] The light beam can also pass through the etalon in reverse order, such that the substrate 725 acts as the first etalon and the reference etalon 762 acts as the second etalon. In this embodiment, the first light beam 732 passes through the substrate 725 before passing through the reference etalon 762. Either the transmitted or reflected light through the substrate 725 can be transmitted to the reference etalon 762.

[0059] Controller 770 is coupled to the first process chamber 700. Controller 770 is configured to facilitate control and automation of the methods described herein. Controller 770 may be coupled to or communicate with light source 744, radiation measurement device 746, spectrometer 748, process gas sources 734, 742, exhaust pump 740, power supply 752, 720, and actuator 718. Controller 770 may communicate with or be coupled to CPU 772 (i.e., computing system). CPU 772 may be a hardware unit or a combination of hardware units capable of executing software applications and processing data. In some configurations, CPU 772 includes a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a graphics processing unit (GPU), and / or a combination of these units. CPU 772 is generally configured to execute one or more software applications and process stored media data. Controller 770 may include memory 774. This memory is a non-transitory computer-readable medium for storing instructions, as described herein, for determining substrate temperature. CPU 772 may be one of any form of general-purpose computer processor that can be used in an industrial environment to control various chambers and subprocessors, such as a programmable logic controller (PLC). Memory 774 is coupled to CPU 772 and is non-transitory, and may be one or more of readily available memory (such as random access memory (RAM), read-only memory (ROM), floppy disk drive, hard disk, or any other form of digital storage (local or remote)). Support circuitry 776 is coupled to CPU 772 for conventionally supporting the processor. Temperature measurements and other processes are typically stored in memory 774, typically as part of the software's common programming. The software can also be stored and / or executed by a second CPU (not shown), which is located away from the hardware controlled by the CPU 772.

[0060] Memory 774 is in the form of a computer-readable storage medium containing instructions that, when executed by CPU 772, facilitate the operation of the first process chamber 700. The instructions in memory 774 are in the form of a program product, such as a program that implements the methods of this disclosure. The program code may conform to any of many different programming languages. In one instance, this disclosure may be implemented as a program product stored on a computer-readable storage medium for use with a computer system. The program(s) of the program product define the functionality of the embodiments (including the methods described herein).

[0061] In some embodiments, (several) programs embody machine learning capabilities. Various data features include process parameters such as processing time, temperature, pressure, voltage, polarity, power, gaseous substances, precursor flow rates, and the like. Relationships between features are identified and defined so that data can be acquired and the process performed in the first process chamber 700 can be adapted through analysis by machine learning algorithms. The machine learning algorithms may employ supervised or unsupervised learning techniques. Examples of machine learning algorithms embodyed in the programs include, but are not limited to, linear regression, logistic regression, decision trees, state vector machines, neural networks, Naive Bayes, k-nearest neighbors, k-means, random forests, dimensionality reduction algorithms, gradient boosting algorithms, and other algorithms. In one example, the machine learning algorithm is used to adjust temperature measurements of the substrate.

[0062] Illustrative computer-readable storage media include, but are not limited to: (i) non-writable storage media that permanently stores information (e.g., read-only memory devices within a computer, such as CD-ROM disks readable by a CD-ROM drive, flash memory, ROM chips, or any type of solid-state non-volatile semiconductor memory); and (ii) writable storage media that stores changeable information (e.g., floppy disks or hard disk drives within floppy disk drives, or any type of solid-state random access semiconductor memory). Such computer-readable storage media are embodiments of this disclosure when carrying computer-readable instructions instructing the functions of the methods described herein.

[0063] Although the etalon assembly 708 is shown as mechanically coupled to the top surface of the first process chamber 700, the etalon assembly 708 may also be a remote etalon assembly such that only the optical waveguide 751 and the second collimator 757 are positioned on top of and / or through the first process chamber 700.

[0064] Figure 8A illustrates a schematic diagram of a second process chamber 800. The second process chamber 800 is similar to the first process chamber 700, but includes an additional second etalon assembly 802. The second etalon assembly 802 is similar to the etalon assembly 708 (referred to as the first etalon assembly). The second etalon assembly 802 is configured to measure the temperature near the edge of the substrate 725, while the first etalon assembly 708 measures the temperature near the center of the substrate 725.

[0065] The second etalon assembly 802 includes a second etalon reference 820, a second light source 808, a third collimator 816 disposed between the second light source 808 and the second etalon reference 820, a second radiation measurement device 810, and a spectrometer 748. The second etalon reference 820 and the third collimator 816 are housed within the second etalon body 806. The second etalon body 806 prevents external light and radiation from entering the second etalon assembly 802 and serves as an outer casing for the second etalon assembly 802. The second etalon body 806 further serves to hold the second etalon reference 820 and the third collimator 816 in place during use of the second etalon assembly 802.

[0066] The third beam 824 is generated by the second light source 808 and passes through one or more waveguides 812. The waveguides 812 may be optical fibers or optical tubes. The waveguides 812 are configured to transmit the third beam 824 from the second light source 808 to the third collimator 816 before it is subsequently transmitted to the second component reference etalon 820. The third beam 824 is similar to the first beam 732.

[0067] A third beam 824 is configured to be transmitted into a beam splitter 813. The beam splitter 813 is similar to the beam splitter 751 and is configured to transfer the third beam 824 from the second component reference etalon 820 to the third collimator 816. After passing through the second component reference etalon 820, the third beam 824 is transmitted into the process volume 728 via an opening 804 within the chamber cover 704 or chamber body 702. The opening 804 may further contain a fourth collimator 821, configured to collimate the light as it is transmitted into the process volume 728. The fourth collimator 821 is coupled to the beam splitter 813 such that the third beam 824 is transmitted from the second component reference etalon 820 into the beam splitter 813 and then to the fourth collimator 821. The opening 804 may be further configured to allow process gas to be introduced into the process volume 728. Process gases can be introduced into the internal volume of the second etalon assembly 802 via a second process gas source 742 or a third process gas source (not shown). In some embodiments, the third process gas source is the same as the second process gas source 742.

[0068] In some embodiments, at least a portion of the opening 804 is covered by a fourth collimator 821. In some embodiments, the opening 804 is completely blocked by a window or the fourth collimator 821. The window separates the process volume 728 from the volume inside the second component body 806 and may help maintain a constant temperature of the second component reference etalon 820.

[0069] The second component reference standard 820 is held in place using the second etalon housing 818. The third beam 824 is configured to pass through the second component reference standard 820. The second etalon housing 818 is configured to hold one or more reference standards in place, such as the second component reference standard 820 and alternative second component reference standards 822. Each of the second component reference standard 820 and alternative second component reference standards is housed within the second etalon housing 818. The second etalon housing 818 is configured to reposition each of the second component reference standards 820, 822 relative to the third beam 824 such that a selected of the second component reference standards 820, 822 is movable into the path of the third beam 824. As shown in Figure 8A, the second component reference standard 820 is housed within the path of the third beam 824. The second etalon housing 818 can be configured to rotate about an axis to switch which of the second component reference etalons 820, 822 is incident on the third beam 824. For example, the second etalon housing 818 can be coupled to a stepper or servo motor that rotates the second etalon housing 818 to selectively move one of the second component reference etalons 820, 822 into the beam path. The second etalon housing 818 may alternatively include more or fewer reference etalons, such as only the second component reference etalon 820, or three or more reference etalons.

[0070] Similar to reference etalons 762, 764, and 766, each of the second component reference etalons 820 and 822 has a different thickness and / or a different refractive index. The different thickness and / or different refractive index allow the second component reference etalons 822 to be selected to match at least one of the refractive index and / or thickness of the substrate 725. In some embodiments, the thickness of the second component reference etalons 820 and 822 within the path of the third beam 824 is selected to match the thickness of the substrate 725 to a difference of about 10%, such as less than about 15 μm, such as less than about 10 μm. This close matching of the thickness and / or refractive index of the second component reference etalons 820 and 822 to the thickness of the substrate 725 achieves the heterodyne of the third beam 824. In some embodiments, the second component reference etalons 820, 822 can be manually selected by replacing one of the reference etalons from the etalon housing 818 with another reference etalon having a thickness and / or refractive index that matches the substrate 725. In the embodiments described herein, the third beam 824 intersects the substrate 725 at a radial position similar to the radial position of the second temperature sensor 724.

[0071] One or more second temperature control units 819 are used to maintain each of the second component reference etalons 820, 822 at a predetermined temperature. The second temperature control unit 819 is similar to the temperature control unit 761 and is configured to control the heating / cooling of the second component reference etalons 820, 822 of the second etalon assembly 802.

[0072] The end of waveguide 812 is held in place by waveguide sleeve 814, which is configured to introduce the third beam 824 into the second component body 806. Waveguide sleeve 814 is similar to waveguide sleeve 754 and is configured to hold the end of waveguide 812 in place adjacent to the third collimator 816.

[0073] The second radiation measurement device 810 is configured to measure one or more fourth beams 825. The fourth beams 825 may be reflected or transmitted fourth beams. The fourth beams 825 are generated from the third beam 824 after the third beam 824 passes through the substrate 725. The substrate 725 acts as a second etalon. In some embodiments, the substrate 725 may be referred to as a sample etalon. When the third beam 824 intersects the substrate 725, the third beam 824 splits into a transmitted fourth beam and a reflected fourth beam. The fourth beam 825 depicted in Figure 8A is a reflected fourth beam and returns to the second component body 806 through the process volume 728. The fourth beams 825 are then collected in one or more waveguides 812 and delivered to the second radiation measurement device 810.

[0074] The fourth light beam 825 transmitted to the second radiation measuring device 810 is measured and analyzed to determine the intensity and wavelength of the light transmitted to the second radiation measuring device 810. The second radiation measuring device 810 is similar to the radiation measuring device 746.

[0075] The data collected by the second radiation measuring device 810 is transmitted to the spectrometer 748. The spectrometer 748 may be able to receive data from the second radiation measuring device 810.

[0076] The beam splitter 813 includes at least three openings. After passing through the reference etalon 820, the first opening of the beam splitter 813 collects the third beam 824. After returning through the fourth collimator 821, the second opening of the beam splitter 813 collects the fourth beam 825. The third opening of the beam splitter 813 is optically coupled to the second radiation measurement device 810. The third opening of the beam splitter 813 is configured to deliver one or a combination of the third beam 824 and the fourth beam 825 to the second radiation measurement device 810.

[0077] In some embodiments, additional temperature measurements are collected along the radius of the substrate 725 using an additional etalon assembly. In some embodiments, the first etalon assembly 708 may include an additional reference etalon, but only includes a single light source 744. In embodiments with only a single light source 744, the first beam 732 may be split into multiple beams before or after passing through the reference etalon 762. In some embodiments, at least one beam is directed to each region of the substrate associated with a temperature control zone (such as a heating zone or a cooling zone) of a substrate support supporting the substrate. Each of these temperature control zones is individually controlled using one or more heating elements or cooling elements. The one or more heating elements may include lamps, resistance heaters, or heating conduits. The one or more cooling elements may include cooling conduits. Multiple beams may be directed from a plurality of etalon assemblies or a single etalon assembly, wherein the beams are split before entering the process volume.

[0078] Figure 8B illustrates a schematic diagram of a third process chamber 850. The third process chamber 850 is similar to the second process chamber 800, but contains a single light source 744 and a single radiation measurement device 746. In the third process chamber 850, a beam splitter 852 is coupled between the light source 744 and each of the waveguides 750 and 812 leading to the first etalon assembly 708 and the second etalon assembly 802. The beam splitter 852 includes one or more optical elements and is configured to split a primary beam from the light source 744 into a first beam 732 and a third beam 824. The primary beam is delivered from the light source 744 to the beam splitter 852 along the waveguide 854. Similarly, both beam-splitting waveguides 751 and 811 are coupled to the radiation measurement device 746. The second beam 731 and the fourth beam 825 are configured to guide the radiation measurement device 746. The radiation measurement device 746 can therefore analyze beams 731 and 825 simultaneously.

[0079] In some embodiments, only one etalon assembly, such as a first etalon assembly 708, is used, but the first beam is split into a first emitted beam and a second emitted beam before entering the process volume. The first emitted beam and the second emitted beam can be guided at different angles such that the first emitted beam intersects the center of the substrate, while the second emitted beam intersects the edge of the substrate.

[0080] Figure 9A illustrates a schematic diagram of a fourth process chamber 900. The fourth process chamber 900 is similar to the first process chamber 700 in Figure 7. The difference between the fourth process chamber 900 and the first process chamber 700 is that the first light beam 912 is configured to be incident on the substrate 725 before reference etalons 762, 764, or 766. In the embodiment of Figure 9A, the light source 904 is disposed separately from the etalon assembly 902. The etalon assembly 902 is similar to the etalon assembly 708 in Figure 7, but does not include the light source 744. The light source 744 is replaced by the separately disposed light source 904.

[0081] Light source 904 is similar to light source 744. Light source 904 is individually connected to waveguide 906, waveguide sheath 908, and first beam collimator 910. Waveguide 906 is similar to waveguide 750, waveguide sheath 908 is similar to waveguide sheath 754, and first beam collimator 910 is similar to collimator 756. Waveguide 906 is configured to transfer first beam 912 from light source 904 to collimator 756. The distal end of waveguide 906 is held in place by waveguide sheath 908, which intersects with chamber cover 704 and / or chamber body 702. Before being transmitted into process volume 728, first beam 912 is transmitted through first beam collimator 910. First beam 912 is transmitted through process volume 728 and intersects with substrate 725. As shown herein, first beam 912 intersects substrate 725 at an angle.

[0082] Once the first beam 912 intersects the substrate 725, the first beam 912 transforms into a second beam 914. The second beam 914 is similar to the second beam 731. The second beam 914 is either a transmitted second beam or a reflected second beam. In the embodiment of Figure 9A, the second beam 914 is a reflected second beam. Before intersecting with one of the reference etalons 762, 764, and 766, the second beam 914 is rearward reflected through the opening 730 and enters the etalon assembly 902. The second beam 914 then produces heterodyne with the reference etalon (such as reference etalon 762). After passing through the reference etalon 762, the second beam 914 passes through the collimator 756 and enters the radiation measurement device 746.

[0083] Figure 9B illustrates a schematic diagram of the fifth process chamber 925. The fifth process chamber 925 is similar to the fourth process chamber 900, but the light source 904 is configured to guide the first beam 912 upward through the substrate base 712, through the substrate 725, and into the etalon assembly 902. In the fifth process chamber 925, the second beam 914 is transmitted light passing through the substrate 725. At least the waveguide sheath 908 and the beam collimator 910 are disposed below or within the substrate base 712 and / or the shaft 716, such that the waveguide sheath 908 and the beam collimator 910 are disposed below the substrate base 712 and the substrate 725.

[0084] The first light beam 912 is configured to pass through an opening 926 within the substrate base 712 and the shaft 716. The opening 926 may be filled with an optically transparent material, optical fiber, or waveguide, depending on the application. The first temperature sensor 722 may be positioned radially similar to the location where the first light beam 912 passes through the substrate 725. In the fifth process chamber 925, the radial position where the first light beam 912 intersects the substrate 725 and the radial position of the first temperature sensor 722 are off-center. The opening 926 may be a hole or slit through the substrate base 712, allowing light to pass through it.

[0085] Figure 9C illustrates a schematic diagram of a sixth process chamber 950. The sixth process chamber 950 is similar to the fifth process chamber 925, but replaces the etalon assembly 902 with an etalon assembly 960. The etalon assembly 960 is configured to receive the second beam 914 after it has passed through at least a portion of the substrate base 712 and / or the shaft 716. A light source 904 is configured to guide the first beam 912 downwards from the chamber cover 704 toward the substrate 725. The first beam 912 is transmitted through the substrate 725 and through an opening 926 within the substrate base 712 and the shaft 716 before passing through one of the reference etalons 762, 764, and 766 of the etalon assembly 960. The etalon assembly 960 is optically coupled to the bottom of the chamber body 702 via a waveguide 962, and a waveguide sheath 908 and / or a beam collimator 910 are positioned through the chamber cover 704. The second collimator 757 is replaced by a second collimator 964. The second collimator 964 is coupled to the farthest end of the waveguide 962 from the opening 926 and is sized to allow light / radiation to pass through the waveguide 962 into the etalon assembly 960. The sixth process chamber 950 is similar to the fifth process chamber 925 because the second beam 914 is transmitted through the substrate 725.

[0086] Figure 10 illustrates a method 1000 for determining substrate temperature. Method 1000 can be used in any of the first process chamber 700, the second process chamber 800, the third process chamber 850, the fourth process chamber 900, the fifth process chamber 925, the sixth process chamber 950, or another processing chamber or other location requiring accurate temperature control. In one example, method 1000 is stored as a software common program in the memory of controller 770. When method 1000 is executed by controller 770, controller 770 causes the temperature of substrate 725 to be determined using the apparatus disclosed herein. Method 1000 uses a first etalon and a second etalon to determine the temperature of one of the second etalons. The first etalon can be a reference etalon, and the second etalon can be a sample etalon (i.e., the substrate). The first and second etalons generate heterodynes to form an interference pattern. From this interference pattern, the fringe spacing can be measured to determine the temperature of the substrate.

[0087] At operation 1002 of method 1000, a first beam is passed through a first etalon and a substrate, wherein the substrate forms a second etalon. In one example, the first etalon is a reference etalon, and the substrate is a sample etalon. The substrate may be a semiconductor substrate, such as substrate 725 of Figures 7, 8A to 8B, and 9A to 9C. The substrate described herein is a sample substrate and is formed of a predetermined material. The sample substrate is an additional substrate input into the process chamber for process calibration. The sample substrate is configured to have desired optical characteristics, such as optical transparency. The sample substrate may be optically transparent between wavelengths of about 1000 nm and about 1800 nm, such as about 1100 nm to about 1700 nm. The sample substrate described herein may be one of silicon, silicon oxide, silicon nitride, silicon carbide, or silicon-germanium materials. In some embodiments, the refractive index of the sample substrate is about 2 to about 6, such as about 3 to about 5, at wavelengths from about 1000 nm to about 1800 nm.

[0088] The first etalon may be any one of the reference etalons 762, 764, 766, 820, and 822 in Figures 7, 8A to 8B, and 9A to 9C. The first etalon and the substrate have similar thicknesses and refractive indices, such that the thicknesses of each of the first etalon and the substrate are matched to a difference of less than about 10%. The first beam may be similar to beams 732, 824, and 912 in Figures 7, 8A to 8B, and 9A to 9C. The first beam is a broad-spectrum beam. The first beam may first pass through the first etalon or the substrate. In embodiments using devices similar to those in Figures 7, 8A, and 8B, the first beam first passes through the first etalon. In embodiments using devices similar to those in Figures 9A to 9C, the first beam first passes through the substrate.

[0089] In an embodiment where the first beam first intersects with the first standard, during operation 1004, the first beam is then transmitted into the process volume and intersects with the substrate to form a reflected second beam and a transmitted second beam from the first beam. The reflected second beam is the portion of the first beam reflected by the substrate. The transmitted second beam is the portion of the first beam transmitted through the substrate. Either or both of the reflected second beam and the transmitted second beam form the second beam. In the embodiments of Figures 7, 8A, and 8B, the second beam is a reflected second beam.

[0090] In another embodiment, the first beam is transmitted into the process volume before first intersecting the substrate. After intersecting the substrate, during operation 1004, the first beam is split into a reflected second beam and a transmitted second beam. The reflected second beam is the portion of the first beam reflected by the substrate. The transmitted second beam is the portion of the first beam transmitted through the substrate. Either or both of the reflected second beam and the transmitted second beam form the second beam. In the embodiment of Figure 9A, the second beam is a reflected second beam. The second beam is then configured to intersect with a first etalon, wherein the second beam is transmitted or reflected by the first etalon. In the embodiment of Figure 9A, the portion of the second beam passing through the first etalon is transmitted to a radiation measuring device, such as radiation measuring device 746. In the embodiments of Figures 9A and 9B, the second beam is a transmitted second beam. The second beam is then configured to intersect with the first etalon, wherein, similar to Figure 9A, the second beam is transmitted or reflected by the first etalon.

[0091] After the second beam is formed during operation 1004, during operation 1006, the second beam is collected by a radiometric device using one or more waveguides (such as waveguides 750, 812). The second beam is collected by the radiometric device after intersecting with the first etalon and the substrate, such that heterodyne has been introduced into the second beam by the first etalon and the substrate. The collection of the second beam allows it to be analyzed by the radiometric device and the spectrometer. As described herein, the radiometric device may be a spectrometer or multiple spectrometers.

[0092] After the second beam is transmitted to the radiation measuring device during operation 1006, the fringe spacing of the second beam is determined from the interference pattern during operation 1008. The interference pattern is generated by the collected reflected or transmitted second beam and may be similar to the interference patterns in Figures 4 and 5. A spectrometer (such as spectrometer 748) may be used to determine the fringe spacing. The spectrometer receives, processes, stores, and analyzes the data provided by the radiation measuring device. The spectrometer identifies the spectral interference fringe spacing (such as fringe spacing 215 in Figure 4 and / or fringe spacing 315 in Figure 5) to infer one or more temperature measurements of the substrate.

[0093] The fringe spacing determined during operation 1008 is related to the temperature of the substrate. Therefore, the temperature of the substrate is determined based on the fringe spacing during operation 1010. The temperature is determined by matching the measured fringe spacing with a fringe spacing expected for similar materials at a specific temperature. In the embodiments described herein, the spectrometer and / or controller includes a reference table for a specific material and thickness, which has a temperature-dependent fringe spacing. In some embodiments, the data is associated with a graph, equation, or script such that the temperature of the substrate can be determined at the point where the first beam intersects the substrate by knowing the fringe spacing, the temperature of the first etalon (reference etalon), the material of the substrate, and the bulk thickness of the substrate.

[0094] When determining the temperature of the substrate during operation 1010 of method 1000, the temperature of the first etalon, the material of the substrate, and the bulk thickness of the substrate are used as constants, while the fringe spacing varies with the temperature of the substrate. Therefore, once each of the temperature of the first etalon, the material of the substrate, the bulk thickness of the substrate, and the fringe spacing of the substrate is known, the temperature can be determined by a spectrometer and / or controller. A lookup table, reference table, or relationship diagram for relating the fringe spacing to temperature can be determined empirically within the desired temperature range. For a particular material, empirically derived data can be obtained within a specific thickness and temperature range. In some embodiments, empirical data for silicon, silicon oxide, silicon nitride, silicon carbide, and germanium silicon are obtained. The refractive index of the sample substrate is about 2 to about 6, such as about 3 to about 5, at wavelengths from about 1000 nm to about 1800 nm. Empirical data relate to low temperatures and / or temperatures from approximately -200°C to approximately 700°C, such as approximately -196°C to approximately 700°C, such as approximately -196°C to approximately 500°C. Empirical data relating fringe spacing to temperature takes into account the thermo-optical coefficient of the substrate and any thermal expansion of the substrate as its temperature increases or decreases. Thermal expansion can be passively considered in the empirical data by performing experiments that determine the total optical thickness of the substrate over a given temperature range. This total optical thickness includes both the refractive index and the thickness of the substrate.

[0095] For method 1000 of Figure 10 (where one or more temperature measurements of the substrate are determined), the bulk thickness of the substrate is known before performing method 1000. A separate thickness calibration process can be used to determine the bulk thickness of the substrate. This thickness calibration process may include manually measuring the temperature of the substrate using calipers, micrometers, or digital measuring tools. The thickness calibration process may also include a standard etalon thickness calibration method, such as method 1100 of Figure 11. Method 1100 of Figure 11 may utilize principles and equipment similar to method 1000 of Figure 10.

[0096] Figure 11 illustrates a method 1100 for determining the thickness of a substrate using a etalon assembly, such as etalon assemblies 708, 802, 902, 960, or other suitable etalon assemblies as shown in Figures 7, 8A to 8B, and 9A to 9C. Method 1100 uses a first etalon and a substrate at a known temperature to determine the thickness of the substrate. During method 1100, during operation 1102, the substrate and process chamber are brought to a first temperature. This first temperature can be any suitable process temperature. In some embodiments, the first temperature is approximately room temperature. The substrate and process chamber are maintained at the first temperature for a time period, allowing the substrate and process chamber to reach a stable state. The temperature of the substrate is measured using one or more temperature sensors (such as temperature sensors 722, 724). When the temperature measurements of the temperature sensors stabilize within a predetermined time period, it can be determined that the entire substrate, substrate support, and process chamber are in a stable state. The temperature measurement value of the temperature sensor can be used as the temperature of the substrate.

[0097] When at the first temperature, operations 1002, 1004, 1006, and 1008 of method 1000 in Figure 1000 are performed. Operations 1002, 1004, 1006, and 1008 of method 1000 determine the stripe spacing caused by the substrate using a standard etalon assembly. The stripe spacing determination is performed in a manner similar to that of method 1000 in Figure 10 for determining the stripe spacing. After operations 1002, 1004, 1006, and 1008, the substrate thickness is determined during operation 1112. The substrate thickness is determined using the determined stripe spacing and the temperature of the substrate / process chamber.

[0098] The substrate described in method 1100 is a sample substrate and is formed of a predetermined material. The sample substrate is configured to have desired optical characteristics, such as optical transparency. The sample substrate may be optically transparent in the wavelength range of about 1000 nm to about 1800 nm, such as about 1100 nm to about 1700 nm. The sample substrate described herein may be one of silicon, silicon oxide, silicon nitride, silicon carbide, or silicon-germanium materials. The refractive index of the sample substrate is about 2 to about 6 in the wavelength range of about 1000 nm to about 1800 nm, such as about 3 to about 5.

[0099] Using relationships similar to those discussed in method 1000, a lookup table and / or relationship diagram can be used to determine the thickness of the substrate, such that by knowing the fringe spacing, the temperature of the first etalon (reference etalon), the material of the substrate, and the temperature of the substrate, the thickness of the substrate can be determined at the point where the first beam intersects the substrate. When determining the thickness of the substrate during operation 1112 of method 1100, the temperature of the first etalon, the material of the substrate, and the temperature of the substrate are used as constants, while the fringe spacing varies with the thickness of the substrate. Therefore, once each of the temperature of the first etalon, the material of the substrate, the temperature of the substrate, and the fringe spacing of the substrate is known, the thickness of the substrate can be determined by a spectrometer and / or controller.

[0100] Figure 12 illustrates a method 1200 for calibrating the temperature within a process chamber, such as one of process chambers 700, 800, 850, 900, 925, and 950 in Figures 7, 8A to 8B, and 9A to 9C, or other suitable process chambers. During method 1200, one or more etalon components (such as one of etalon components 708, 802, 902, and 960) are used to determine the temperature or temperature set. Temperature calibration may include any or a combination of the following: calibrating temperature sensors within the process chamber using the determined temperature; applying a temperature offset to one or more measurements of the temperature sensors; adjusting the model of the process performed in the process chamber; and / or adjusting the process parameters of the process performed in the process chamber.

[0101] During method 1200, during operation 1202, a datum assembly is calibrated for a specific substrate within the process chamber, as appropriate. Calibration of the datum assembly is performed to determine the thickness of the substrate disposed within the process chamber and to match the thickness of the substrate within the process chamber with the thickness of a first datum for subsequent process operations. Operation 1202 includes all of method 1100 and operations 1102, 1002, 1004, 1006, 1008, and 1112. Once the substrate thickness has been determined using method 1100, the first datum (i.e., the reference datum) can be adjusted or exchanged to more closely match the substrate thickness. In the embodiments described herein, the difference between the substrate thickness and the thickness of the first datum is within approximately 10%.

[0102] When using the embodiments described herein, a first reference etalon (e.g., first reference etalon 762) can be removed from the path of the first beam and replaced by a second or third reference etalon, such as second reference etalon 764 and third reference etalon 766. The reference etalon is changed only when the original reference etalon thickness differs from the substrate by a predetermined percentage (e.g., greater than 10%). For example, substrates within a batch or between batches of substrates may have different thicknesses, and therefore appropriate different reference etalons will be switched in place in the etalon assembly. In some embodiments, the reference etalon is changed to a reference etalon having a percentage difference of less than 8% relative to the substrate, such as less than 5% relative to the substrate. The reference etalon can be changed by actuating a turntable containing multiple reference etalons (e.g., etalon housing 760) or by manually inserting a new reference etalon after removing a previous reference etalon.

[0103] In some embodiments, method 1100 is executed multiple times within method 1200, such that method 1100 is executed for the first time and the thickness of the substrate is determined to have a percentage difference greater than a predetermined threshold relative to a reference standard. The reference standard is changed to a second reference standard, and method 1100 is repeated a second time. If the thickness of the substrate is determined to have a percentage difference less than the predetermined threshold relative to the reference standard, operation 1202 is completed. If the thickness of the substrate is still determined to have a percentage difference beyond the threshold relative to the second reference standard, the second reference standard is replaced with a third reference standard, and method 1100 is repeated a third time. This process continues until the percentage difference between the substrate and the reference standard is below the threshold.

[0104] Following operation 1202, a plasma-containing process can be performed during operation 1205 within the process chamber and on the substrate. This plasma-containing process can be either a plasma etching process or a plasma deposition process. Plasma etching includes conductor and / or dielectric etching. Deposition processes include one or more of chemical vapor deposition, sputtering deposition, and atomic layer deposition. The processes described herein are particularly well-suited for processes that incorporate plasma (such as plasma 726) within the process chamber. The processes described herein enable accurate measurement of the substrate temperature within the process chamber while simultaneously forming plasma within the process volume.

[0105] When operation 1205 is performed, a first temperature of the substrate is determined using a standard etalon assembly during operation 1204, and a second temperature of the substrate and / or a second temperature of the substrate support adjacent to the substrate is determined using one or more temperature sensors (such as a first temperature sensor 722 or a second temperature sensor 724) during operation 1206. The first temperature of the substrate is determined using method 1000 of Figure 10 such that the temperature determined based on the stripe spacing during operation 1010 of method 1000 is the first temperature. During operation 1010 of method 1000, the substrate thickness can be input as the thickness determined using operation 1202. The first temperature can be a single first temperature value or a first temperature dataset, such as an array of single temperature values.

[0106] During operation 1206, one or more temperature sensors are disposed adjacent to the bottom surface of the substrate. The one or more temperature sensors measure the temperature of the bottom surface of the substrate and generate a single second temperature value or a second temperature data set, such as an array of single temperature values. The first temperature measurement and the second temperature measurement are performed simultaneously so that the first temperature measurement value and the second temperature measurement value can be compared later.

[0107] During operations 1204 and 1206, a process is performed on a substrate within the process chamber. In the embodiments described herein, the process performed on the substrate is a semiconductor formation process and includes plasma formed within the process volume. The process performed during operation 1205 is similar to the process that would be performed within the process volume during normal operation. Using a process similar to that during normal operation allows for a direct comparison between temperatures measured by an etalon assembly and one or more temperature sensors during operations 1204 and 1206. The ability to compare the process operations in both methods allows for more accurate calibration or correction of one of the temperature sensors, process models, and / or process parameters.

[0108] After the first temperature and the second temperature are determined during operations 1204 and 1206, the first temperature and the second temperature are transmitted to the controller during operation 1208. In some embodiments, the first temperature and / or the second temperature have been determined within the controller, and the data used to determine the first temperature and / or the second temperature is sent to the controller during operations 1204 and 1206. The controller collects the first temperature measurement and the second temperature measurement to enable comparison between the temperature measurements.

[0109] During operation 1210, the process chamber is calibrated using the first temperature and the second temperature. Calibrating the process chamber may include any or a combination of the following: calibrating temperature sensors (such as temperature sensors 722, 724) within the process chamber using a determined temperature; applying a temperature offset to one or more measurements of the temperature sensors; adjusting the model of the process performed in the process chamber; and / or adjusting the process parameters of the process performed in the process chamber.

[0110] Calibrating the temperature sensor includes adjusting the temperature sensor to align with a first temperature measurement of the etalon assembly. In some embodiments, a single temperature offset may be applied to the measured second temperature to more closely correlate it with the first temperature. In some embodiments, the model of the process performed in the processing chamber is adjusted to account for inaccurate or drifting second temperature measurements. In some embodiments, one or more process parameters of the process performed in the process chamber are changed to improve the process results. The process parameters may be adjusted for repetitive processes where similar results and inputs are expected between iterations.

[0111] Once the process chamber has been calibrated using the first and second temperatures during operation 1210, the process volume can be removed from the substrate, and the process chamber can be removed from the etalon assembly as needed. The process chamber can then be operated normally to process the substrate placed therein. The apparatus and methods described herein can be used to periodically recalibrate the system during maintenance procedures. The temperature measurement method using etalons as described herein has been shown to be useful in processes including plasma, because the fringe spacing measured by a radiation measurement device is not significantly affected by plasma. In some embodiments, additional collimators and / or filters are used within the system described herein.

[0112] Although the foregoing describes an embodiment of this disclosure, other and additional embodiments of this disclosure may be designed without departing from the basic scope of this disclosure, and the scope of this disclosure is determined by the following claims. [Simplified Explanation of the Diagram]

[0009] Therefore, the above-described features of this disclosure can be understood in detail by referring to the embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the accompanying drawings illustrate only exemplary embodiments and should not be construed as limiting their scope, allowing for other equally effective embodiments.

[0010] Figure 1 illustrates a standard tether and related concepts.

[0011] Figure 2 shows the relationship between transmittance and wavelength for a standard thickness silicon semiconductor substrate.

[0012] Figure 3 shows a pair of standard objects aligned along the optical axis.

[0013] Figure 4 shows another graph showing the relationship between the transmittance and wavelength of a pair of silicon semiconductor substrates of standard thickness.

[0014] Figure 5 shows another graph showing the relationship between transmittance and wavelength for a pair of silicon semiconductor substrates of standard thickness.

[0015] Figure 6 shows the relationship between the thermo-optic coefficient of a silicon semiconductor substrate from room temperature to approximately 300°C and temperature.

[0016] Figure 7 is a schematic diagram of a first process chamber according to an embodiment of the present disclosure.

[0017] Figure 8A is a schematic diagram of the second process chamber according to an embodiment of the present disclosure.

[0018] Figure 8B illustrates a schematic diagram of a third process chamber according to an embodiment of this disclosure.

[0019] Figure 9A is a schematic diagram of the fourth process chamber according to an embodiment of the present disclosure.

[0020] Figure 9B illustrates a schematic diagram of the fifth process chamber according to an embodiment of this disclosure.

[0021] Figure 9C illustrates a schematic diagram of the sixth process chamber according to an embodiment of the present disclosure.

[0022] Figure 10 illustrates a method for determining the temperature of a substrate according to an embodiment of this disclosure.

[0023] Figure 11 illustrates a method for determining the thickness of a substrate according to an embodiment of this disclosure.

[0024] Figure 12 illustrates a method for calibrating the temperature inside a process chamber according to an embodiment of this disclosure.

[0025] For ease of understanding, the same element symbols have been used to denote common elements in the figures where possible. It is contemplated that elements and features of one embodiment may be advantageously incorporated into other embodiments without further description. [Biomaterial Storage]

[0114] Domestic Storage Information (Please note in order of storage institution, date, and number) None

[0115] Overseas Deposit Information (Please note in the order of deposit country, institution, date, and number) None

Claims

1. A semiconductor processing chamber, comprising: a first etalon; a substrate support; a light source positioned to guide a first light beam through the first etalon and a substrate disposed on the substrate support, wherein the substrate provides a second etalon, and the first etalon and the second etalon form an etalon assembly, and one of the first etalon or the second etalon generates a reflected second light beam and a transmitted second light beam from the first light beam; a spectrometer configured to determine a fringe spacing from an interference pattern generated within one of the reflected second light beam or the transmitted second light beam of the etalon assembly; and a controller configured to determine a temperature of the substrate based on the fringe spacing, and to calibrate the semiconductor processing chamber at least partially based on the temperature, wherein calibrating the semiconductor processing chamber includes calibrating a temperature sensor within the semiconductor processing chamber using the temperature.

2. The semiconductor processing chamber as claimed in claim 1, wherein calibrating the semiconductor processing chamber includes applying a temperature offset to one or more measurements of a temperature sensor within the semiconductor processing chamber.

3. The semiconductor processing chamber as claimed in claim 1, wherein calibrating the semiconductor processing chamber includes adjusting a model of a process performed in the semiconductor processing chamber.

4. The semiconductor processing chamber as claimed in claim 1, wherein calibrating the semiconductor processing chamber includes adjusting a process parameter of a process performed in the semiconductor processing chamber.

5. The semiconductor processing chamber as claimed in claim 1, wherein the first beam from the first etalon is guided to the substrate and further includes performing a plasma process on the substrate while guiding the first beam through a plasma.

6. The semiconductor processing chamber as claimed in claim 1, wherein before determining the temperature, the semiconductor processing chamber and the substrate are brought to a stable temperature, and an initial substrate temperature measurement is used to calculate a thickness of the substrate, and a first thickness of the first standard is adjusted based on a second thickness of the substrate by placing an alternative first standard in a path of the first beam.

7. A method suitable for sensing temperature in a semiconductor processing chamber, the method comprising the steps of: passing a first light beam through a first etalon; passing the first light beam through a substrate disposed in the semiconductor processing chamber, the substrate providing a second etalon; passing a reflected second light beam through both the first etalon and the second etalon, and generating the reflected second light beam and a transmitted second light beam from the first light beam; determining a fringe spacing from an interference pattern of either the reflected second light beam or the transmitted second light beam; and determining a temperature of the substrate based on the fringe spacing; wherein, before determining the fringe spacing, the semiconductor processing chamber and the substrate are brought to a stable temperature, and a thickness of the substrate is calculated using an initial substrate temperature measurement, and a first thickness of the first etalon is adjusted to be within 10 μm of a second thickness of the substrate by removing the first etalon from a path of the first light beam and placing an alternative first etalon in the path of the first light beam.

8. The method as described in claim 7, wherein the fringe spacing is related to an empirically derived thermo-optic coefficient value of either the first or the second etalon.

9. The method of claim 7, wherein the step of guiding the first light beam through the first etalon and the substrate disposed in the semiconductor processing chamber further comprises at least one of the following steps: guiding the first light beam to a surface of the substrate remote from the semiconductor processing chamber and in a direction toward the cover; or guiding the first light beam to a surface of the substrate facing the semiconductor processing chamber and in a direction away from the cover.

10. The method of claim 7, wherein the step of guiding the first beam from the first etalon to the substrate further comprises the step of guiding the first beam through a plasma while performing a plasma process on the substrate disposed in the semiconductor processing chamber.

11. The method as described in claim 7, wherein the step of placing the alternative first reference datum in the path of the first beam further comprises the following steps: automatically moving the first beam and at least one of the first reference datums of the plurality of reference datums to alignment based on the thickness of the substrate.

12. The method as described in claim 7 further comprises the step of: directing at least the first beam and a third beam to different locations of the substrate disposed in the semiconductor processing chamber.

13. The method as described in claim 12, wherein the step of guiding the first beam and the third beam further comprises the steps of: guiding the first beam to a central region of the substrate and guiding the third beam to an edge region of the substrate.

14. The method as described in claim 12, wherein the guiding step further comprises the following steps: guiding at least one light beam to each region of the substrate associated with a temperature control zone of a substrate support that supports the substrate within the semiconductor processing chamber.

15. The method as described in claim 7 further comprises one or more of the following steps: calibrating a temperature sensor within the semiconductor processing chamber using the temperature; applying a temperature offset to one or more measurements of the temperature sensor; adjusting a model of a process performed in the semiconductor processing chamber; and adjusting a process parameter of the process performed in the semiconductor processing chamber.

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