Closed-loop control of a plasma source via feedback from a laser absorption species sensor

Abstract

The embodiments disclosed in this specification include semiconductor processing tools. In one embodiment, the semiconductor processing tool includes a chamber, a pedestal in the chamber configured to hold a substrate, and a plasma source above the pedestal. In one embodiment, a laser light source is connected to the chamber, and a detector is connected to the chamber directly opposite the laser light source. In one embodiment, the detector is configured to be optically coupled to the laser light source.

Description

Cross - reference to related applications

[0001] This application claims priority to U.S. Patent Application No. 17 / 841,561, filed on June 15, 2022, the entire content of which is incorporated herein by reference.

Technical Field

[0002] Embodiments relate to the field of semiconductor manufacturing, and more particularly, to laser - absorption - species sensors for controlling plasma sources.

Background Art

[0003] Plasma processing tools, such as plasma deposition chambers and plasma etching chambers, may rely on the generation of radical species to process substrates within the processing tool. Currently, the concentration of radical species generated within the chamber is an unknown value. In addition, plasma sources are prone to performance drift over time. This can lead to significantly different results on the substrate. The performance of the substrate is monitored daily with a dummy substrate, and the parameters of the plasma source are adjusted in an uncertain way to correct for chamber drift. The entire batch of substrates may be lost before the parameters of the processing tool are correctly adjusted.

[0004] Currently, there are no plasma sources on the market that employ closed - loop control of plasma. This is largely because there is no diagnostic tool for monitoring radical generation. Instead, most tools use past data to adjust the performance of the tool. Such a process is a trial - and - error approach to process control. This currently used trial - and - error approach can lead to substrates on the tool being defective for an entire day. Furthermore, changes made based on monitor substrates using past data do not guarantee satisfactory performance the next day. Thus, in existing plasma processing tools, significant impacts on yield are currently being observed.

Summary of the Invention

[0005] The embodiments disclosed herein include semiconductor processing tools. In one embodiment, the semiconductor processing tool includes a chamber, a pedestal within the chamber configured to hold a substrate, and a plasma source above the pedestal. In one embodiment, a laser light source is connected to the chamber, and a detector is connected to the chamber directly opposite the laser light source. In one embodiment, the detector is configured to be optically coupled to the laser light source.

[0006] The embodiments may further include a method of processing a substrate within a semiconductor processing tool. In one embodiment, the method includes generating a plasma within a processing chamber, propagating a laser through the chamber using a laser light source, and detecting the laser using a detector after the laser has passed through the chamber. In one embodiment, the method further includes detecting absorption of the laser using a detector after the laser has passed through the chamber, and controlling the plasma within the processing chamber in response to the detected absorption of the laser.

[0007] The embodiments disclosed herein may further include a semiconductor processing tool. In one embodiment, the semiconductor processing tool includes a remote plasma chamber, a processing chamber, wherein the remote plasma chamber is connected to the processing chamber by a pipe, and a pedestal within the processing chamber configured to support a substrate. In one embodiment, the semiconductor processing tool includes a laser light source connected to a first window within the semiconductor processing tool, and a detector connected to a second window within the semiconductor processing tool, wherein the laser light source and the detector are configured to be optically coupled to each other.

Brief Description of the Drawings

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DETAILED DESCRIPTION OF THE INVENTION

[0009] The systems described herein include a laser absorption species sensor for controlling a plasma source. In the following description, numerous specific details are set forth in order to provide a comprehensive understanding of the embodiments. It will be apparent to those skilled in the art that the embodiments may be practiced without these specific details. In other instances, well-known aspects have not been described in detail so as not to obscure the embodiments unnecessarily. Further, it should be understood that the various embodiments shown in the accompanying figures are exemplary representations and are not necessarily drawn to scale.

[0010] As described above, there is currently no closed-loop control system within the plasma processing tool. Instead, a dummy substrate is periodically driven, and changes to the plasma processing tool are made based on past data obtained during the processing of the dummy substrate. Since chamber control is directed based on past data, it is difficult to properly adjust the process in the plasma processing tool. This can lead to significant yield losses. In addition, once the plasma processing tool is properly adjusted, the process may deviate from the specifications due to chamber drift, and it may be necessary to drive another dummy substrate to recalibrate the tool. The inability to constantly monitor the performance of the tool can also lead to chamber matching problems between various chambers.

[0011] In response, embodiments disclosed herein include a plasma processing tool that enables closed-loop control. Closed-loop control can be provided using laser absorption spectroscopy. Laser absorption spectroscopy includes propagating a laser through the internal space of the chamber. Species within the chamber absorb a portion of the laser intensity. Therefore, by measuring the absorption of the laser using a detector, a quantitative measurement of the concentration of species within the chamber becomes possible. The measured value of the species concentration can be fed back to a plasma controller to modify one or more process parameters and ultimately return the species concentration to a desired value. For example, one or more of gas flow rate, power supplied to the plasma, frequency of the plasma, pressure within the processing chamber, and temperature of the processing chamber can be changed to adjust the species concentration.

[0012] In one embodiment, laser absorption spectroscopy can be performed within a remote plasma source (RPS) tool. In such an embodiment, the laser source and detector can be provided along a pipe between the remote plasma chamber and the processing chamber. In other embodiments, the laser light source and detector can be provided within the main processing chamber. For example, the laser light source and detector can be provided within a range of 10 mm from the substrate. By moving the laser light source and detector closer to the substrate, the measurement of the concentration of species that interact directly with the substrate can be made more accurate as a result. In other embodiments, standard plasma processing tools can be used. That is, the plasma source can directly induce plasma within the main processing chamber above the substrate.

[0013] It should be understood that not all types of radicals or species are amenable to laser absorption spectroscopy. In such cases, the measurement line can be provided in fluid parallel with the main processing chamber. The measurement line can include a first chamber that is a reaction chamber. Within the reaction chamber, radicals (or species) are introduced into the chamber and reacted with a first gas. The first gas reacts with the radicals to form a second gas. The second gas can include species that can be measured using laser absorption spectroscopy. The second gas then flows into a second chamber that is a measurement chamber. The second chamber can include a window to allow the laser to pass through the chamber to determine the absorption of the second gas. The absorption of the second gas can be directly correlated with the concentration (or flux) of radical species.

[0014] Referring now to FIG. 1A, a cross-sectional view of a semiconductor processing tool 100 according to one embodiment is shown. The semiconductor processing tool 100 can include any type of plasma processing tool. For example, the semiconductor processing tool 100 can be a plasma etching chamber or a plasma deposition chamber. The semiconductor processing tool 100 can be a stand-alone tool, or the semiconductor processing tool 100 can be part of a cluster tool. That is, a plurality of repetitions of the semiconductor processing tool 100 (or various processing tools) can be mechanically connected by a central hub chamber.

[0015] In the illustrated embodiment, the semiconductor processing tool 100 is shown as an RPS tool. The RPS semiconductor processing tool 100 can include a plasma chamber 130, a pipe 120, and a main processing chamber 110. The pipe 120 can fluidly connect the plasma chamber 130 and the main processing chamber 110. In the illustrated embodiment, the plasma chamber 130 is located above the main processing chamber 110. However, the embodiment is not limited to such a configuration, and the plasma chamber 130 can be provided at any position around the main processing chamber 110. As shown, the plasma 115 substantially remains within the plasma chamber 130.

[0016] The plasma chamber 130 is shown as a featureless chamber for simplicity. However, it should be understood that the plasma chamber 130 can include a lid or showerhead through which gas flows into the chamber. The lid can also function as an RF source or a microwave source for generating plasma within the plasma chamber 130. In one embodiment, the volume of the plasma chamber 130 is smaller than the volume of the main processing chamber 110.

[0017] In one embodiment, the main processing chamber 110 may include a pedestal 105. In one embodiment, the pedestal 105 may include a chuck structure. For example, the pedestal 105 may include an electrostatic chuck (ESC). The pedestal 105 may also include a thermal control (e.g., heating or cooling) structure to control the temperature of the substrate 107 fixed by the pedestal 105. In one embodiment, the substrate 107 may be any substrate suitable for semiconductor processing steps. For example, the substrate 107 may be a semiconductor wafer such as a silicon wafer. The substrate 107 may also include glass, ceramic, or organic materials. In one embodiment, the substrate 107 may have any form factor. For example, the substrate 107 may be a 300 mm wafer, or a 450 mm wafer, etc. An evacuation device (not shown) may also be provided within the main processing chamber 110.

[0018] In one embodiment, the laser absorption spectroscopy tool may include a laser light source 141 and a detector 142. The laser light source 141 can be connected above a first window 143 that penetrates the sidewall of the pipe 120, and the detector 142 can be connected above a second window 144 that penetrates the sidewall of the pipe 120. In one embodiment, the laser light source 141 and the detector 142 may be present closer to the plasma chamber 130 than the main processing chamber 110.

[0019] In one embodiment, the laser 145 propagated by the laser light source 141 passes through the space of the pipe 120 and is optically coupled to the detector 142. In one embodiment, the laser light source 141 may be a laser of any suitable wavelength suitable for laser absorption spectroscopy. For example, according to one embodiment, a laser light source 141 of 1278 nm may be used. The detector 142 may be any type of optical detector. For example, the detector 142 may be a charge-coupled device (CCD).

[0020] Referring now to FIG. 1B, a cross-sectional view of a semiconductor processing tool 100 according to one embodiment is shown. The semiconductor processing tool 100 can include any type of plasma processing tool. For example, the semiconductor processing tool 100 can be a plasma etching chamber or a plasma deposition chamber. The semiconductor processing tool 100 can be a stand-alone tool or the semiconductor processing tool 100 can be part of a cluster tool.

[0021] In the illustrated embodiment, the semiconductor processing tool 100 is shown as an RPS tool. The RPS semiconductor processing tool 100 can include a plasma chamber 130, a pipe 120, and a main processing chamber 110. The pipe 120 can fluidly connect the plasma chamber 130 and the main processing chamber 110.

[0022] The plasma chamber 130 is shown as a featureless chamber for the sake of simplicity. However, it should be understood that the plasma chamber 130 can include a lid or showerhead through which gas flows into the chamber. The lid also functions as an RF source or microwave source for colliding plasma within the plasma chamber 130. In one embodiment, the volume of the plasma chamber 130 is smaller than the volume of the main processing chamber 110.

[0023] In one embodiment, the main processing chamber 110 can include a pedestal 105. In one embodiment, the pedestal 105 can include a chuck structure such as an ESC structure. The pedestal 105 can also include a thermal control (e.g., heating or cooling) structure to control the temperature of the substrate 107 fixed by the pedestal 105. In one embodiment, the substrate 107 can be any substrate suitable for semiconductor processing steps. For example, the substrate 107 can be a semiconductor wafer such as a silicon wafer, although other substrate materials can also be used. An evacuation device (not shown) can also be provided within the main processing chamber 110.

[0024] In one embodiment, the laser absorption spectroscopy tool may include a laser light source 141 and a detector 142. The laser light source 141 can be connected above a first window 143 that penetrates the sidewall of the pipe 120, and the detector 142 can be connected above a second window 144 that penetrates the sidewall of the pipe 120. In one embodiment, the laser light source 141 and the detector 142 may be present closer to the main processing chamber 110 than the plasma chamber 130. In such an embodiment, as a result, the concentration of the species being measured can be close to the concentration of the species interacting with the substrate 107.

[0025] In one embodiment, a laser 145 propagated by the laser light source 141 passes through the space of the pipe 120 and is optically coupled to the detector 142. In one embodiment, the laser light source 141 can be a laser of any suitable wavelength suitable for laser absorption spectroscopy. For example, according to one embodiment, a laser light source 141 of 1278 nm can be used. The detector 142 can be any type of optical detector. For example, the detector 142 can be a CCD.

[0026] Referring now to FIG. 1C, a cross-sectional view of a semiconductor processing tool 100 according to one embodiment is shown. The semiconductor processing tool 100 can include any type of plasma processing tool. For example, the semiconductor processing tool 100 can be a plasma etching chamber or a plasma deposition chamber. The semiconductor processing tool 100 can be a stand-alone tool, or the semiconductor processing tool 100 can be part of a cluster tool.

[0027] In the illustrated embodiment, the semiconductor processing tool 100 is shown as an RPS tool. The RPS semiconductor processing tool 100 can include a plasma chamber 130, a pipe 120, and a main processing chamber 110. The pipe 120 can fluidly connect the plasma chamber 130 and the main processing chamber 110.

[0028] For the sake of simplicity, the plasma chamber 130 is shown as a featureless chamber. However, it should be understood that the plasma chamber 130 may include a lid or showerhead through which gas flows into the chamber. The lid may also function as an RF source or microwave source for generating plasma within the plasma chamber 130. In one embodiment, the volume of the plasma chamber 130 is smaller than the volume of the main processing chamber 110.

[0029] In one embodiment, the main processing chamber 110 may include a pedestal 105. In one embodiment, the pedestal 105 may include a chuck structure such as an ESC structure. The pedestal 105 may also include a thermal control (e.g., heating or cooling) structure for controlling the temperature of the substrate 107 fixed by the pedestal 105. In one embodiment, the substrate 107 can be any substrate suitable for semiconductor processing steps. For example, the substrate 107 can be a semiconductor wafer such as a silicon wafer, but other substrate materials can also be used. An evacuation device (not shown) can also be provided within the main processing chamber 110.

[0030] In one embodiment, the laser absorption spectroscopy tool may include a laser light source 141 and a detector 142. The laser light source 141 can be connected above a first window 143 that penetrates the sidewall of the main processing chamber 110, and the detector 142 can be connected above a second window 144 that penetrates the sidewall of the main processing chamber 110. In one embodiment, the laser light source 141 and the detector 142 can be present relatively close to the substrate 107. For example, the laser 145 can be separated from the substrate 107 by about 10 mm or less. In certain embodiments, the laser 145 can be separated from the substrate 107 by about 5 mm or less. In such embodiments, as a result, the measured concentration of the species can be close to the concentration of the species that actually interacts with the substrate 107.

[0031] In one embodiment, a laser 145 propagated by a laser light source 141 passes through the space of the main processing chamber 110 and is optically coupled to a detector 142. In one embodiment, the laser light source 141 can be a laser of any suitable wavelength suitable for laser absorption spectroscopy. For example, according to one embodiment, a laser light source 141 of 1278 nm can be used. The detector 142 can be any kind of optical detector. For example, the detector 142 can be a CCD device.

[0032] Referring now to FIG. 2, a cross-sectional view of a semiconductor processing tool 200 according to one embodiment is shown. In one embodiment, the semiconductor processing tool 200 can be any plasma chamber such as a plasma etching chamber or a plasma deposition chamber. In contrast to the embodiments of the RPS described above, the semiconductor processing tool 200 can be a standard plasma tool according to one embodiment. That is, the plasma 215 is generated within the same space as the substrate 207.

[0033] The plasma 215 can be generated using an RF source or a microwave source connected to the lid 211 of the chamber 210. The lid 211 can include a conductive feature that couples a microwave or RF signal to the process gas within the chamber 210 to generate the plasma 215. In one embodiment, the lid 211 may be a gas showerhead. That is, gas (e.g., process gas, inert gas, etc.) can flow into the chamber 210 through the lid 211. The gas flow path through the lid 211 is omitted for simplicity. Additionally, in some embodiments, the gas may flow into the chamber 210 through a surface other than the lid 211.

[0034] In one embodiment, the pedestal 205 can be provided within the chamber 205. In one embodiment, the pedestal 205 can include a chuck structure such as an ESC structure. The pedestal 205 can also include a thermal control (e.g., heating or cooling) structure to control the temperature of the substrate 207 fixed by the pedestal 205. In one embodiment, the substrate 207 can be any substrate suitable for semiconductor processing steps. For example, the substrate 207 can be a semiconductor wafer such as a silicon wafer, but other substrate materials can also be used. An exhaust device (not shown) can also be provided within the processing chamber 210.

[0035] In one embodiment, the laser absorption spectroscopy tool can include a laser light source 241 and a detector 242. The laser light source 241 can be connected above a first window 243 that penetrates the side wall of the processing chamber 210, and the detector 242 can be connected above a second window 244 that penetrates the side wall of the processing chamber 210. In one embodiment, the laser light source 241 and the detector 242 can be present relatively close to the substrate 207. For example, the laser 245 can be separated from the substrate 207 by about 10 mm or less. In a specific embodiment, the laser 245 can be separated from the substrate 207 by about 5 mm or less. In such embodiments, as a result, the measured concentration of the species can be close to the concentration of the species that actually interacts with the substrate 207.

[0036] In one embodiment, the laser 245 propagated by the laser light source 241 passes through the space of the processing chamber 210 and is optically coupled to the detector 242. In one embodiment, the laser light source 241 can be a laser of any suitable wavelength suitable for laser absorption spectroscopy. For example, according to one embodiment, a laser light source 241 of 1278 nm can be used. The detector 242 can be any type of optical detector. For example, the detector 242 can be a CCD.

[0037] Referring now to FIG. 3A, a graph of laser absorption - wavelength is shown for one embodiment. The graph shown has a plurality of different gas flow rates indicated. In one embodiment, the measured gas flow rate can be for one or more gases flowing into the chamber. For example, the process gas can include NF3. In one embodiment, the gas flow rate can be in the range from 40 sccm to 150 sccm, although lower or higher gas flow rates can also be used. As shown, higher gas flow rates correspond to higher absorption rates. Referring now to FIG. 3B, a graph of species concentration versus gas flow rate is shown for one embodiment. In the specific case of NF3 gas, the partial pressure can be that of the HF species. As shown, higher gas flow rates correspond to higher species concentrations. By combining the graph of FIG. 3A and the graph of FIG. 3B, it is possible to calculate the species concentration in a given process using the laser absorption rate.

[0038] Referring now to FIG. 4A, a graph of laser absorption - wavelength is shown for one embodiment. The graph shown has a plurality of different power supply levels indicated. In one embodiment, the power supply can refer to the power supplied to the plasma in the chamber. In one embodiment, the supplied power can be in the range from 310 W to 415 W, although lower and higher powers can also be used. As shown, higher supplied powers correspond to higher absorption rates. Referring now to FIG. 4B, a graph of species concentration (i.e., partial pressure) versus supplied power is shown for one embodiment. As shown, higher supplied powers correspond to higher species concentrations. By combining the graph of FIG. 4A and the graph of FIG. 4B, it is possible to calculate the species concentration in a given process using the laser absorption rate.

[0039] In FIGS. 3A - 4B, examples of gas flow rates and supplied powers are used to show how laser absorption spectroscopy can be used to determine species concentrations. However, it should be understood that other plasma parameters can also be used to vary the species concentrations measured by a laser absorption spectroscopy tool. For example, the plasma frequency, the pressure within the processing chamber, and the temperature of the processing chamber can also be changed to vary the species concentration within the chamber. Further, while an example of HF is provided as the measured species concentration, it should be understood that other species or combinations of species can also be monitored. For example, the concentration of one or more of HF, O, Ar, N, NH, NH2, NH3, F, He, H, H2, F2, NF, NF2, NF 3、 Cl, HCl, CH, CH2, CH3, CH4, C2H2, C, H2O, OH, H2S, HS, PH, PH2, PH3, P, SiH, SiH2, SiH3, SiH4, and Si can be monitored by laser absorption spectroscopy.

[0040] Referring now to FIG. 5, a cross - sectional view of a semiconductor processing tool 500 according to one embodiment is shown. In one embodiment, the semiconductor processing tool 500 can be substantially similar to the semiconductor processing tool 100 shown in FIG. 1A. For example, a plasma chamber 530 can be fluidly connected to a main processing chamber 510 by a pipe 520. The main processing chamber 510 can include a pedestal 505 and a substrate 507 on the pedestal 505. In one embodiment, a plasma 515 can be generated within the plasma chamber 530. Further, a laser absorption spectroscopy tool including a laser light source 541 and a detector 542 can be included. The laser light source 541 and the detector 542 can be optically coupled to each other via windows 543 and 544 provided in the pipe 520. The laser 542 can pass between the windows 543 and 544 from the laser light source 541 to the detector 542.

[0041] In FIG. 5, a feedback loop 555 is also included. The feedback loop 555 can return to the plasma controller 550. The plasma controller 550 can be used to control one or more parameters of plasma generation in the plasma chamber 530. For example, the plasma controller 550 can control gas flow rate, power supplied to the plasma, frequency of the plasma, pressure within the plasma chamber 530, and temperature of the plasma chamber 530. The feedback loop 555 can provide a closed-loop control solution for monitoring and controlling the concentration of species within the semiconductor processing tool. Thus, it is possible to control the processing conditions without relying on past data and / or dummy substrates.

[0042] Referring now to FIG. 6, a process flow diagram of a process 660 according to one embodiment is shown. In one embodiment, the process 660 can be used to control the concentration of species within a semiconductor processing chamber.

[0043] In one embodiment, the process 660 can begin with a step 661 that includes generating plasma within the processing chamber. In one embodiment, the processing chamber can be similar to any of the processing chambers described in more detail herein. For example, the processing chamber can be an RPS chamber or a standard plasma chamber.

[0044] In one embodiment, the process 660 can follow with a step 662 that includes propagating a laser through the chamber using a laser light source. The laser light source can be any suitable wavelength for laser absorption spectroscopy and in some embodiments can even include multiple wavelengths. As the laser passes through the chamber, the laser interacts with the species and power is absorbed from the laser.

[0045] In one embodiment, process 660 may follow step 663 that includes detecting the laser using a detector after the laser has passed through the chamber. In one embodiment, the detector may be a CCD or other optical detection structure. In one embodiment, the detector may be on the opposite side from the laser source. Thus, the laser can propagate straight across the chamber from the laser source to the detector. The laser source and the detector may be outside the window that penetrates the sidewall of the chamber.

[0046] In one embodiment, process 660 may follow step 664 that includes detecting the absorption of the laser using a detector after the laser has passed through the chamber. In one embodiment, the amount of laser absorption can be correlated with the density of the species in the chamber.

[0047] In one embodiment, process 660 may follow step 665 that includes controlling the plasma in the processing chamber in response to the detected absorption of the laser. For example, feedback from the laser absorption can be used to change one or more plasma variables such as, for example, gas flow rate, power supplied to the plasma, frequency of the plasma, pressure in the processing chamber, and temperature of the processing chamber.

[0048] As described above, not all radical species or other species can be directly measured by laser absorption spectroscopy. In response to this, the embodiments disclosed herein further include a measurement line capable of converting a radical (or species) into a species that can be measured by a laser absorption spectroscopy process. In some embodiments, the measurement line is in fluid parallel with the main processing chamber. In other embodiments, the measurement line can be directly connected to the main processing chamber. In yet another embodiment, the measurement line is downstream of the main processing chamber. In one embodiment, the measurement line may include a reaction chamber and a measurement chamber. In other embodiments, the reaction chamber and the measurement chamber can be combined into a single structure.

[0049] Referring now to FIG. 7A, a schematic diagram of a semiconductor processing tool 700 according to one embodiment is shown. In one embodiment, the semiconductor processing tool 700 may include a remote plasma source 730. Although an embodiment including the remote plasma source 730 is shown, it should be understood that any device capable of generating radicals may be used in place of the remote plasma source 730.

[0050] In one embodiment, the remote plasma source 730 may be fluidly connected to the main processing chamber 710. The main processing chamber 710 may include a chuck or the like for fixing a substrate (not shown). The main processing chamber may be used as a deposition chamber, an etching chamber, or other chamber for semiconductor processing including radical species.

[0051] In one embodiment, the main processing chamber 710 may be fluidly connected to a pump 713. The pump 713 provides a low pressure environment (e.g., a vacuum environment) for the main processing chamber 710. As is common in semiconductor manufacturing tools, a chamber throttle valve 711 and a chamber isolation valve 712 may be provided between the pump 713 and the chamber 710.

[0052] In one embodiment, a pressure P U may be provided between the remote plasma source 730 and the main chamber 710. Inside the chamber 710, a chamber pressure P CH can be provided, and in the pump 713, a pump pressure TIFF2025523759000002.tif7170 can be provided. In one embodiment, the pressure P U is greater than the pressure P CH , and the pressure P CH is greater than the pressure TIFF2025523759000003.tif7170.

[0053] In one embodiment, the measurement line can be provided fluidly in parallel with the chamber 710. That is, the inlet to the measurement line can be upstream of the chamber 710, and the outlet of the measurement line can be downstream of the chamber 710. For example, the inlet to the measurement line can be provided between the remote plasma source 730 and the chamber 730, and the outlet of the measurement line can be provided between the shut-off valve 712 and the pump 713.

[0054] In one embodiment, the measurement line is configured to modify radicals (or species) generated by the remote plasma source 730 such that the radicals (or species) are suitable for laser absorption spectroscopy. For example, it is possible to carry out a controlled chemical reaction with the radicals (or species) to generate new species that can be detected by laser absorption spectroscopy. In this case, the measurement of the new species can be used to calculate the concentration or flux of the original radicals (or species).

[0055] In one embodiment, the measurement line can include a reaction cell 731. The reaction cell 731 can be a chamber in which radicals are reacted to form new species. Thus, in some cases, the reaction cell 731 can be referred to as the reaction chamber 731. In one embodiment, the reaction cell 731 can receive radicals as a first input, and the reaction cell 731 can receive a first gas as a second input. The radicals and the first gas can react with each other to form a second gas. The second gas includes species that can be measured using laser absorption spectroscopy. A more detailed description of the reaction cell 731 is provided below.

[0056] In certain embodiments, the radical or species of interest can be fluorine. In such embodiments, the first gas is H2, C X H Y X Z (where X is F or Cl), C X H Y, one or more of NH3, B2H6, and H2O may be included. By reacting F with the first gas, HF that can be measured by laser absorption spectroscopy can be generated. In other embodiments, the radical or species of interest can be chlorine. In such embodiments, the first gas is H2, C X H Y X Z (where X is F or Cl), C X H Y , one or more of NH3, B2H6, and H2O may be included. By reacting Cl with the first gas, HCl that can be measured by laser absorption spectroscopy can be generated. In other embodiments, the radical or species of interest can be oxygen. In such embodiments, the first gas is C X H Y , one or more of H2, NH3, or B2H6 may be included. By reacting O with the first gas, one or more of CO, CO2, and H2O that can be measured by laser absorption spectroscopy can be generated. In yet another embodiment, the radical or species of interest can be hydrogen. In such embodiments, the first gas is NF3, C X F Y X Z (where X is F or Cl), Cl2, F2, SF6, SiH X F (4-X) , SiH X Cl (4-X) , GeH X F (4-X) , and GeH X Cl (4-X) may be included. By reacting H with the first gas, HF and HCl that can be measured by laser absorption spectroscopy can be generated. The radical may also include sulfur, phosphorus, or silicon. OH, the reaction can also be NH, NH2, NH3, HS, H2S, PH, PH2, PH3, C x H yOne or more of SiH, SiH₂, SiH₃, and SiH₄ can also be generated. Although some examples of material classes are shown, it will be understood that any radical or species capable of reacting to form new species measurable by laser absorption spectroscopy can be used in accordance with the embodiments described herein.

[0057] In one embodiment, the measurement line may further include a measurement cell 732. The measurement cell 732 can be a chamber in which a second gas is measured using laser absorption spectroscopy. Thus, the measurement cell 732 may sometimes be referred to as the measurement chamber 732 or the absorption chamber 732. In one embodiment, the measurement cell 732 can receive a second gas as an input. Thereafter, the second gas is measured using laser absorption spectroscopy. For example, a pair of windows facing each other can enable a laser to pass through the measurement cell 732 and be detected by a photodetector. A more detailed description of the measurement cell 732 is provided below.

[0058] In one embodiment, the measurement cell 732 can have a pressure P A In one embodiment, the pressure P A is U less than the pressure P and greater than the pressure A The pressure P U and TIFF2025523759000005.tif7170. In additional embodiments, a mass flow meter (MFM) 734 can be provided between the throttle valve 733 and the pump 713.

[0059] Referring now to FIG. 7B, a schematic diagram of a semiconductor processing tool 700 according to one embodiment is shown. The semiconductor processing tool 700 of FIG. 7B may be substantially the same as the semiconductor processing tool 700 of FIG. 7A, except for the fluid connection of the measurement line. Instead of being in fluid parallel with the main processing chamber 710, the upstream side of the measurement line is connected to the chamber 710. Thus, the flux of radicals entering the chamber can be determined by the measurement line. In the illustrated embodiment, a remote plasma source 730 is shown. However, it should be understood that a plasma source integrated with the main processing chamber 710 can also be used. The measurement line may have a downstream end that connects to the gas line between the shut-off valve 712 and the pump 713.

[0060] Referring now to FIG. 7C, a schematic diagram of a semiconductor processing tool 700 according to one embodiment is shown. In one embodiment, the semiconductor processing tool 700 of FIG. 7C may be substantially the same as the semiconductor processing tool 700 of FIG. 7A, except for the fluid connection of the measurement line. Instead of being in fluid parallel with the main processing chamber 710, the upstream side of the measurement line is connected to the gas line between the main chamber 710 and the throttle valve 711. In this way, the flux of radicals exiting the chamber can be determined by the measurement line. In the illustrated embodiment, a remote plasma source 730 is shown. However, it should be understood that a plasma source integrated with the main processing chamber 710 can also be used. The measurement line may have a downstream end that connects to the gas line between the shut-off valve 712 and the pump 713.

[0061] In FIGS. 7A - 7C, three different measurement line structures are shown. However, it should be understood that in some embodiments, the three different measurement line structures can be combined with each other. For example, two or more different measurement lines can be provided within a single semiconductor processing tool 700. That is, a single semiconductor processing tool 700 can include a first measurement line including an input between the plasma source and the main chamber, a second measurement line including an input in the main chamber, and a third measurement line including an input downstream of the main chamber.

[0062] Referring now to FIG. 8A, a cross-sectional view of a reaction cell 831 that can be used within a semiconductor processing tool is shown, according to one embodiment. In one embodiment, the reaction cell 831 can include a chamber 821. The chamber can be fluidly connected to the main process line of the plasma processing tool. For example, the reaction cell 831 can be fluidly connected between a remote plasma source and the main chamber, fluidly connected to the main chamber, or fluidly connected downstream of the main chamber, similar to the embodiments shown in FIGS. 7A-7C.

[0063] In one embodiment, the chamber 821 can have a plurality of gas supply lines. A supply line 822 can be used to introduce radicals 827 into the chamber 821 from a remote plasma source (or other source of radicals or species). In one embodiment, a second supply line 823 is used to introduce a first gas 828 into the chamber 821. The flow rate of the first gas 828 can be controlled by a mass flow controller (not shown). Thus, a specific amount of the first gas 828 can flow into the chamber 821 and react with the species 827 to form a second gas 829. In one embodiment, a third supply line 824 can function as an outlet from the chamber 821. The second gas 829 can exit the chamber 821 through the third supply line 824. In one embodiment, the second gas 829 can include the species being measured. In additional embodiments, the second gas 829 has other species that are part of the reaction between the radicals and the first gas but are not the species being measured.

[0064] In one embodiment, the chamber 821 can also include a thermometer 825 or any other device capable of measuring temperature. The thermometer 825 can be used to control the temperature of the chamber 821. For example, the chamber 821 can be heated or cooled to promote a particular reaction. Additionally, the chamber 821 can include a transducer 826. The transducer 826 can be used in combination with a throttle valve (e.g., throttle valve 733 of FIG. 7A) to control the pressure within the chamber 821.

[0065] Referring now to FIG. 8B, a schematic diagram of a measurement cell 832 according to one embodiment is shown. In one embodiment, the measurement cell 832 may include a chamber 836. The chamber 836 may be fluidly connected to the chamber 821 via a third supply line 824. Accordingly, a second gas 829 flows into the chamber 836. The second gas 829 flows through the chamber 821 and exits as gas 835. In one embodiment, the gas 835 may be substantially the same as the second gas 829. That is, no further reaction may occur within the chamber 836.

[0066] In one embodiment, the measurement cell 832 may further include a pair of windows 837 and 838. The window 837 and the window 838 may be located on opposite sides of the chamber 836. A light source 841 (e.g., a laser) can be provided near the window 837, and a photodetector 842 can be provided near the window 838. The light source 841 is configured to emit light 845 that passes through the windows 837 and 838, and the light source 841 is optically coupled to the photodetector 842. The light 845 is partially absorbed by the second gas 829. The amount of absorption of the light 845 is detected by the photodetector 842, and the concentration of the measured species is determined. Thereafter, the concentration of the measured species can be used to calculate the concentration or flux of radical species flowing into the measurement line.

[0067] In one embodiment, the chamber 836 may also include a thermometer 825 or any other device capable of measuring temperature. The thermometer 825 can be used to control the temperature of the chamber 836. For example, the chamber 836 can be heated or cooled. In addition, the chamber 836 may include a transducer 826. The transducer 826 can be used in combination with a throttle valve (e.g., the throttle valve 733 of FIG. 7A) to control the pressure within the chamber 836.

[0068] Referring now to FIG. 9, a diagram combining reaction cell 931 and measurement cell 932 according to one embodiment is shown. That is, instead of having separate chambers (as shown in FIGS. 8A and 8B), cell 931 / 932 can include a single chamber 936. Thus, a chemical reaction (for converting radical species to measurable species) and absorption measurement can be provided within the same chamber 936.

[0069] In one embodiment, radical species 927 can flow into chamber 936. In one embodiment, a first gas 928 also flows into chamber 936. The amount of the first gas 928 flowing into chamber 936 can be controlled by a mass flow controller (not shown). The first gas 928 and the radical species 927 can react to form a second gas 935, and the second gas 935 flows out of chamber 936.

[0070] Furthermore, a laser absorption spectroscopy structure is provided on chamber 936. For example, a pair of windows 937 and 938 can be present on opposite sides of chamber 936. A light source 941 (e.g., a laser) can be provided near window 937, and a photodetector 942 can be provided near window 938. The light source 941 is configured to emit light 945 that passes through windows 937 and 938, and the light source 941 is optically coupled to the photodetector 942. The light 945 is partially absorbed by the second gas 935. The amount of absorption of the light 945 is detected by the photodetector 942, and the concentration of the measured chemical species is determined. Thereafter, the concentration of the measured species can be used to calculate the concentration or flux of the radical species 927 flowing into chamber 936.

[0071] In one embodiment, chamber 936 may also include thermometer 925 or any other device capable of measuring temperature. Thermometer 925 may be used to control the temperature of chamber 936. For example, chamber 936 may be heated or cooled to facilitate a particular reaction. Additionally, chamber 936 may include transducer 926. Transducer 926 may be used in combination with a throttle valve (e.g., throttle valve 733 of FIG. 7A) to control the pressure within chamber 936.

[0072] Referring now to FIG. 10, a process flow diagram of process 1080 for measuring the flux of radicals within a semiconductor processing tool, according to one embodiment, is shown. In one embodiment, process 1080 may be performed using any of the semiconductor processing tools described above that include a measurement line.

[0073] In one embodiment, process 1080 may begin with step 1081, which includes generating radicals using a plasma source. In some embodiments, the radicals may be generated using a remote plasma source. However, other plasma sources may be used depending on the configuration of the semiconductor processing tool. Further, although referred to as radicals, it should be understood that other species may also be generated in step 1081. In certain embodiments, the generated radicals (or species) are radicals (or species) that cannot be easily measured directly using laser absorption spectroscopy. That is, significant expense in equipment and technology would be required to measure the radicals, species, or both. For example, the radicals may include one or more of fluorine, oxygen, chlorine, sulfur, phosphorus, silicon, and hydrogen.

[0074] In one embodiment, process 1080 can follow step 1082 that includes flowing a sample of radicals onto a sampling line. In one embodiment, the radicals can be flowed onto the sampling line before reaching the main processing chamber. In other embodiments, the radicals are flowed onto the sampling line after reaching the main processing chamber. In yet another embodiment, the radicals are flowed onto the sampling line after passing through the main processing chamber. In one embodiment, the downstream side of the sampling line can be connected to a line in front of the pump of the semiconductor processing tool. For example, the downstream side of the sampling line can be provided between a shut-off valve and the pump.

[0075] In one embodiment, process 1080 can follow step 1083 that includes reacting the radicals with a first species to form a second species. In certain embodiments, the radical or species of interest can be fluorine. In such embodiments, the first species can include one or more of H2, C X H Y X Z (where X is F or Cl), C X H Y , NH3, B2H6, and H2O. The reaction of F with the first species can generate a gas containing a second species, HF, measurable by laser absorption spectroscopy. In other embodiments, the radical or species of interest can be chlorine. In such embodiments, the first species can include one or more of H2, C X H Y X Z (where X is F or Cl), C X H Y , NH3, B2H6, and H2O. The reaction of Cl with the first species can generate a gas containing a second species, HCl, measurable by laser absorption spectroscopy. In other embodiments, the radical or species of interest can be oxygen. In such embodiments, the first species is C X H Ymay contain one or more of H2, NH3, or B2H6. By reacting O with the first species, a gas can be generated that contains a second species including one or more of CO, CO2, and H2O that can be measured by laser absorption spectroscopy. In yet another embodiment, the radical or species of interest can be hydrogen. In such an embodiment, the first species is NF3, C X F Y X Z (where X is F or Cl), Cl2, F2, SF6, SiH X F (4-X) 、SiH X Cl (4-X) 、GeH X F (4-X) 、and GeH X Cl (4-X) and may contain one or more of them. By reacting H with the first species, a gas can be generated that contains a second species including one or more of HF and HCl that can be measured by laser absorption spectroscopy. Although some examples of material classes are shown, it will be understood that any radical or species that can be reacted to form a new species measurable by laser absorption spectroscopy can be used in accordance with the embodiments described herein.

[0076] In one embodiment, process 1080 can be followed by step 1084 that includes measuring the second species in an absorption chamber. In one embodiment, the absorption chamber can be similar to either the measurement cell or measurement chamber described in more detail herein. For example, the absorption chamber can include a first window and a second window on both sides of the chamber. A light source (e.g., a laser) can emit light that passes through the first window and the second window. The light source can be optically coupled to a photodetector to determine the level of absorption provided by the second species. In some embodiments, the absorption chamber can be a chamber separate from where the chemical reaction occurs. In other embodiments, the absorption chamber can be the same chamber where the chemical reaction occurs.

[0077] Referring now to FIGS. 11A and 11B, a graph showing the relationship between the measured partial pressure and the etching rate is shown. As shown in FIG. 11A, the partial pressure of HF rises to about 125 W, then decreases and rises again to 175 W. Similarly, the etching rate for the power sweep also shows the same decrease and subsequent increase. That is, the measurement of the partial pressure reflects the etching rate. Further, as shown in FIG. 11B, there is a strong linear trend between the data of the etching rate and the data of the partial pressure of HF. Thus, it is possible to directly correlate the knowledge of the partial pressure of HF with the expected etching rate on the substrate.

[0078] Referring now to FIG. 12, a block diagram is shown in accordance with one embodiment illustrating an exemplary computer system 1200 of a processing tool. In one embodiment, the computer system 1200 is connected to a processing tool and controls processing within the processing tool. The computer system 1200 can be connected (e.g., networked) to other machines in a local area network (LAN), intranet, extranet, or the Internet. The computer system 1200 can operate as a server or client machine in a client - server network environment, or as a peer machine in a peer - to - peer (or distributed) network environment. The computer system 1200 can be a personal computer (PC), tablet PC, set - top box (STB), personal digital assistant (PDA), cellular phone, web appliance, server, network router, switch or bridge, or any machine capable of executing a set of (sequential or otherwise) instructions that specify the actions to be taken by that machine. Further, although only a single machine is shown as the computer system 1200, the term "machine" should also be construed to include any collection of machines (e.g., computers) that individually, or in concert, execute a set of (or multiple sets of) instructions to perform any one or more of the methods described herein.

[0079] The computer system 1200 may include a computer program product or software 1222 having a non-transitory machine-readable medium storing instructions, which may be used to program the computer system 1200 (or other electronic device) to execute the processes according to the embodiments. The machine-readable medium includes any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer). For example, the machine-readable (e.g., computer-readable) medium includes a machine (e.g., computer) readable storage medium (e.g., read only memory (ROM), random access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, etc.), a machine (e.g., computer) readable transmission medium (propagation signals in electrical, optical, acoustic, or other forms (e.g., infrared signals, digital signals, etc.)), etc.

[0080] In one embodiment, the computer system 1200 includes a system processor 1202, a main memory 1204 (e.g., dynamic random access memory (DRAM) such as read only memory (ROM), flash memory, synchronous DRAM (SDRAM), or Rambus DRAM (RDRAM)), a static memory 1206 (e.g., flash memory, static random access memory (SRAM), etc.), and a secondary memory 1218 (e.g., a data storage device), which communicate with each other via a bus 1230.

[0081] The system processor 1202 represents one or more general-purpose processing devices, such as a micro-system processor or a central processing unit. More specifically, the system processor can be a complex instruction set computing (CISC) micro-system processor, a reduced instruction set computing (RISC) micro-system processor, a very long instruction word (VLIW) micro-system processor, a system processor that executes other instruction sets, or a system processor that executes a combination of instruction sets. The system processor 1202 can also be one or more special-purpose processing devices, such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal system processor (DSP), or a network system processor. The system processor 1202 is configured to execute processing logic 1226 for performing the processes described herein.

[0082] The computer system 1200 may further include a system network interface device 1208 for communicating with other devices or machines. The computer system 1200 may also include a video display unit 1210 (e.g., a liquid crystal display (LCD), a light emitting diode display (LED), or a cathode ray tube (CRT)), an alphanumeric input device 1212 (e.g., a keyboard), a cursor control device 1214 (such as a mouse), and a signal generating device 1216 (e.g., a speaker).

[0083] The secondary memory 1218 may include a machine-accessible storage medium 1232 (or, more specifically, a computer-readable storage medium) storing one or more instruction sets (e.g., software 1222) that embody any one or more of the methods or functions described herein. This software 1222 may also reside, in whole or at least in part, within the scope of the main memory 1204 and / or within the scope of the system processor 1202 while being executed by the computer system 1200, and the main memory 1204 and the system processor 1202 may also constitute a machine-readable storage medium. The software 1222 may further be transmitted or received over the network 1220 via the system network interface device 1208. In one embodiment, the network interface device 1208 may operate using RF coupling, optical coupling, acoustic coupling, or inductive coupling.

[0084] In an exemplary embodiment, the machine-accessible storage medium 1232 is shown as a single medium, but the term "machine-readable storage medium" should be interpreted to include a single medium or multiple media (e.g., a centralized database or a distributed database, and / or associated caches and servers) storing one or more instruction sets. The term "machine-readable storage medium" should also be interpreted to include any medium capable of storing or encoding a set of instructions for execution by a machine, the set of instructions being capable of causing a machine to execute any one or more of the methods. Thus, the term "machine-readable storage medium" should be interpreted to include, but not be limited to, solid-state memory, optical media, and magnetic media.

[0085] In the foregoing specification, specific exemplary embodiments have been described. It will be apparent that various modifications may be made to the exemplary embodiments without departing from the scope of the following claims. Correspondingly, this specification and the drawings are to be regarded as illustrative rather than limiting.

Claims

1. A semiconductor processing tool, comprising a chamber, a pedestal within the chamber configured to hold a substrate, a plasma source above the pedestal, a light source connected to the chamber, a detector connected to the chamber and facing the light source, the detector being configured to be optically coupled to the light source, and a semiconductor processing tool comprising the above components.

2. A first optical window passing through the chamber near the light source, a second optical window passing through the chamber near the detector, and the semiconductor processing tool according to Claim 1 further comprising the above components.

3. The semiconductor processing tool according to Claim 1, wherein the light source and the detector are arranged such that the light propagating from the light source to the detector is separated by about 10 mm or less from the pedestal.

4. The semiconductor processing tool according to Claim 1, wherein the plasma source is a remote plasma source.

5. The semiconductor processing tool according to Claim 4, wherein the chamber includes a pipe connecting the plasma source to a lower portion of the chamber.

6. The semiconductor processing tool according to Claim 5, wherein the distance between the light source and the plasma source is smaller than the distance between the light source and the lower portion of the chamber.

7. The semiconductor processing tool according to Claim 5, wherein the distance between the light source and the plasma source is larger than the distance between the light source and the lower portion of the chamber.

8. The semiconductor processing tool according to Claim 1, wherein the light source and the detector are configured to provide laser absorption spectroscopy.

9. The laser absorption spectroscopy method monitors a species containing one or more of HF, O, Ar, N, F, He, H, H ２ , F ２ , NF, NF ２ , NF ３ , Cl, and Si, the semiconductor processing tool according to claim 8, configured to monitor.

10. The semiconductor processing tool according to Claim 1, wherein the semiconductor processing tool is a deposition tool or an etching tool.

11. A method for processing a substrate in a semiconductor processing tool, comprising generating plasma in a processing chamber, using a light source to propagate light through the chamber, detecting the light using a detector after the light has passed through the chamber, detecting absorption of the light using the detector after the light has passed through the chamber, and controlling the plasma in the processing chamber according to the detected absorption of the light. and a method for processing a substrate in a semiconductor processing tool comprising the above steps.

12. The method according to Claim 11, wherein the processing chamber is a remote plasma source (RPS) processing chamber.

13. The method according to claim 12, wherein the light source and the detector are provided along a pipe between the remote plasma chamber and the processing chamber.

14. The method according to claim 11, wherein the distance between the light source and the substrate in the chamber is about 10 mm or less.

15. The method according to claim 11, wherein the absorption of the light is used to determine the concentration of species in the processing chamber.

16. The concentration of said species includes the concentration of one or more of HF, O, Ar, N, F, He, H, H ２ , F ２ , NF, NF ２ , NF ３ , Cl, and Si, the method according to claim 15.

17. The method according to claim 11, wherein controlling the plasma includes changing one or more of gas flow rate, power supplied to the plasma, frequency of the plasma, pressure in the processing chamber, and temperature of the processing chamber.

18. A semiconductor processing tool, comprising: a remote plasma chamber; a processing chamber, wherein the remote plasma chamber is connected to the processing chamber by a pipe; a pedestal in the processing chamber configured to support a substrate; a laser light source connected to a first window in the semiconductor processing tool; a detector connected to a second window in the semiconductor processing tool, wherein the laser light source and the detector are configured to be optically coupled to each other; A semiconductor processing tool comprising the above.

19. The semiconductor processing tool according to claim 18, wherein the first window and the second window are provided through a side wall of the pipe.

20. The semiconductor processing tool according to claim 18, wherein the first window and the second window are provided through a side wall of the processing chamber.

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