Plasma source closed loop control via feedback of laser absorbing species sensor

Abstract

Embodiments disclosed herein include a semiconductor processing tool. In one embodiment, a semiconductor processing tool includes a chamber, a susceptor within the chamber configured to secure a substrate, and a plasma source over the susceptor. In an embodiment, a laser source is coupled to a chamber, and a detector is coupled to the chamber opposite the laser source. In an embodiment, a detector is configured to be optically coupled with a laser source.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. patent application No. 17 / 841,561,5 filed on June 15, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Embodiments relate to the field of semiconductor manufacturing, and more particularly, to a laser absorbing species sensor for controlling a plasma source. Background Art

[0004] Plasma processing tools, such as plasma deposition chambers, plasma etching chambers, etc., may rely on the generation of free radical species to process substrates in the processing tool. Currently, the concentration of free radicals generated in the chamber is an unknown value. In addition, the plasma source is prone to drift in its performance over time. This can lead to drastically different results on the substrate. Dummy substrates are routinely used to monitor substrate performance and adjust plasma source parameters in an uncertain manner to compensate for chamber drift. Entire batches of substrates may be lost until the parameters of the processing tool are correctly adjusted.

[0005] Currently, no plasma source on the market uses plasma closed loop control. The main reason is that there are no diagnostic tools to monitor the generation of free radicals. Instead, most tools use historical data to adjust tool performance. This approach is a blind process control approach. The blind approach currently used can result in a day of failure of substrates on the tool. In addition, changes based on monitoring the substrate and using historical data do not guarantee satisfactory performance the next day. As a result, significant yield degradation is currently observed in existing plasma processing tools. Summary of the invention

[0006] Embodiments disclosed herein include a semiconductor processing tool. In one embodiment, the semiconductor processing tool includes a chamber, a pedestal configured to hold a substrate within the chamber, and a plasma source located above the pedestal. In one embodiment, a laser source is coupled to the chamber, and a detector is coupled to the chamber opposite the laser source. In one embodiment, the detector is configured to be optically coupled to the laser source.

[0007] Embodiments may further include a method of processing a substrate in a semiconductor processing tool. In one embodiment, the method includes initiating a plasma in a processing chamber, propagating laser light through the chamber using a laser source, and detecting the laser light with a detector after the laser light passes through the chamber. In one embodiment, the method further includes detecting absorption of the laser light with a detector after the laser light passes through the chamber, and controlling the plasma in the processing chamber in response to the detected absorption of the laser light.

[0008] The disclosed embodiments 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 coupled to the processing chamber via a conduit; and a pedestal configured to support a substrate in the processing chamber. In one embodiment, the semiconductor processing tool further includes: a laser source coupled to a first viewing window in the semiconductor processing tool; and a detector coupled to a second viewing window in the semiconductor processing tool, wherein the laser source and the detector are configured to be optically coupled to each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1A is a cross-sectional view of a plasma processing tool having a remote plasma source (RPS) including a laser source and a detector provided on a conduit between the RPS and a main processing chamber according to one embodiment.

[0010] Figure 1B is a cross-sectional view of a plasma processing tool having an RPS including a laser source and a detector provided on a conduit between the RPS and a main processing chamber, wherein the laser source and the detector are closer to the main processing chamber than to the RPS, according to one embodiment.

[0011] Figure 1C is a cross-sectional view of a plasma processing tool having an RPS including a laser source and a detector provided in a main processing chamber above a substrate according to one embodiment.

[0012] Figure 2 is a cross-sectional view of a plasma processing tool including a laser source and a detector in a main processing chamber located above a substrate according to one embodiment.

[0013] Figure 3A is a graph of laser absorption for multiple gas flow rates according to one embodiment.

[0014] Figure 3B is a graph of species concentration versus airflow rate according to an embodiment.

[0015] Figure 4A is a graph of laser absorption for various plasma power values ​​according to one embodiment.

[0016] Figure 4B is a graph of species concentration versus delivered power according to an embodiment.

[0017] Figure 5is a cross-sectional view of a plasma processing tool including a laser and a detector coupled to a plasma controller to provide closed-loop control of a plasma within a processing chamber according to one embodiment.

[0018] Figure 6 is a process flow chart for controlling a plasma in a plasma processing tool using closed-loop control based on laser absorption spectroscopy according to one embodiment.

[0019] Fig. 7A is a schematic diagram of a plasma processing tool with a radical concentration measurement line according to one embodiment.

[0020] Figure 7B is a schematic diagram of a plasma processing tool with a radical concentration measurement line according to an additional embodiment.

[0021] Figure 7C is a schematic diagram of a plasma processing tool with a radical concentration measurement line according to an additional embodiment.

[0022] Fig. 8A FIG. 4 is a cross-sectional view of a reaction chamber on a free radical concentration measurement line according to an embodiment.

[0023] Figure 8B FIG. 4 is a schematic diagram of a measurement chamber on a free radical concentration measurement line according to an embodiment.

[0024] Fig. 9 FIG. 4 is a schematic diagram of a combined reaction chamber and a measurement chamber on a free radical concentration measurement line according to an embodiment.

[0025] Fig.10 is a flow chart of a process for measuring radical flux in a semiconductor processing tool according to one embodiment.

[0026] Fig.11A A graph showing HF partial pressure and corresponding etch rate versus power according to an embodiment.

[0027] Fig. 11B A graph showing HF partial pressure versus etch rate according to an embodiment.

[0028] Fig.12 A block diagram is shown of an example computer system that may be used in conjunction with a processing tool according to an embodiment. DETAILED DESCRIPTION

[0029] The system disclosed herein includes a laser absorbing species sensor for controlling a plasma source. In the following description, many specific details are set forth in order to provide a comprehensive understanding of the embodiments. For those skilled in the art, the embodiments can be practiced without these specific details. In other cases, in order not to unnecessarily obscure the embodiments, well-known aspects are not described in detail. In addition, it should be understood that the various embodiments shown in the drawings are merely illustrative representations and are not necessarily drawn to scale.

[0030] As mentioned above, there is no closed loop control system in current plasma processing tools. Instead, dummy substrates are run periodically and changes to the plasma processing tool are made based on historical data obtained during the processing of the dummy substrates. Because the chamber control is determined based on historical data, it is difficult to properly adjust the process on the plasma processing tool. This can result in significant yield losses. In addition, once the plasma processing tool is properly adjusted, chamber drift may cause the process to be out of specification, and another dummy substrate may need to be run to recalibrate the tool. The inability to continuously monitor tool performance may also lead to chamber matching issues between different chambers.

[0031] Thus, embodiments disclosed herein include plasma processing tools capable of closed-loop control. Closed-loop control can be provided using laser absorption spectroscopy. Laser absorption spectroscopy involves propagating a laser through a chamber interior volume. Species within the chamber absorb a portion of the laser intensity. Thus, by measuring the absorption of the laser using a detector, a quantitative measurement of the species concentration within the chamber can be determined. The measurement of the species concentration can be fed back to a plasma controller to modify one or more processing parameters to return the species concentration to a desired value. For example, one or more of the following can be changed to adjust the species concentration: gas flow rate, power supplied to the plasma, plasma frequency, pressure of the processing chamber, and temperature of the processing chamber.

[0032] In one embodiment, laser absorption spectroscopy can be implemented in a remote plasma source (RPS) tool. In such an embodiment, the laser source and detector can be arranged along a conduit between the plasma chamber and the processing chamber. In other embodiments, the laser source and detector can be arranged in the main processing chamber. For example, the laser source and detector can be provided within 10 mm of the substrate. Moving the laser source and detector closer to the substrate can result in more accurate measurements of the concentration of species that interact directly with the substrate. In other embodiments, a standard plasma processing tool can be used. That is, the plasma source can induce plasma above the substrate directly in the main processing chamber.

[0033] It should be understood that not all free radicals or species types are compatible with laser absorption spectroscopy. In this case, a measurement line can be provided in parallel with the main processing chamber fluid. The measurement line can include a first chamber, which is a reaction chamber. In the reaction chamber, free radicals (or species) flow into the chamber and react with a first gas. The first gas reacts with the free radicals to form a second gas. The second gas may include species that can be measured by laser absorption spectroscopy. Then, the second gas flows into the second chamber, which is a measurement chamber. The second chamber may 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 related to the concentration (or flux) of the free radical species.

[0034] Reference now Figure 1A , a schematic cross-sectional view of a semiconductor processing tool 100 is shown according to an embodiment. The semiconductor processing tool 100 may include any type of plasma processing tool. For example, the semiconductor processing tool 100 may be a plasma etching or plasma deposition chamber. The semiconductor processing tool 100 may be a stand-alone tool, or the semiconductor processing tool 100 may be part of a cluster tool. That is, multiple replicates of the semiconductor processing tool 100 (or different processing tools) may be mechanically coupled together via a central hub chamber.

[0035] In the illustrated embodiment, the semiconductor processing tool 100 is shown as a remote plasma source (RPS) tool. The RPS semiconductor processing tool 100 may include a plasma chamber 130, a conduit 120, and a main processing chamber 110. The conduit 120 may fluidly couple the plasma chamber 130 with the main processing chamber 110. In the illustrated embodiment, the plasma chamber 130 is located above the main processing chamber 110. However, embodiments are not limited to such a configuration, and the plasma chamber 130 may be disposed at any location around the main processing chamber 110. As shown, the plasma 115 is substantially maintained in the plasma chamber 130.

[0036] For 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 act as a radio frequency (RF) or microwave source to initiate plasma in 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.

[0037] In one embodiment, the main processing chamber 110 may include a pedestal 105. In one embodiment, the pedestal 105 may include a clamping structure. For example, the pedestal 105 may include an electrostatic chucking (ESC) structure. The pedestal 105 may also include a thermal control (e.g., heating or cooling) structure to control the temperature of a substrate 107 secured by the pedestal 105. In one embodiment, the substrate 107 may be any substrate suitable for semiconductor processing operations. 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 external dimensions. For example, the substrate 107 may be a 300 mm wafer, a 450 mm wafer, etc. An exhaust device (not shown) may also be provided in the main processing chamber 110.

[0038] In one embodiment, the laser absorption spectroscopy tool may include a laser source 141 and a detector 142. The laser source 141 may be coupled to a first window 143 through a sidewall of the duct 120, and the detector 142 may be coupled to a second window 144 through a sidewall of the duct 120. In one embodiment, the laser source 141 and the detector 142 may be closer to the plasma chamber 130 than the main processing chamber 110.

[0039] In one embodiment, laser light 145 propagated by a laser source 141 passes through the volume of the pipe 120 and is optically coupled to a detector 142. In one embodiment, the laser source 141 can be a laser of any suitable wavelength suitable for laser absorption spectroscopy. For example, according to one embodiment, a 1278 nanometer laser source 141 can be used. The detector 142 can be any type of optical detector. For example, the detector 142 can be a charge-coupled device (CCD).

[0040] Reference now Figure 1B , according to an additional embodiment, a cross-sectional view of a semiconductor processing tool 100 is shown. The semiconductor processing tool 100 may include any type of plasma processing tool. For example, the semiconductor processing tool 100 may be a plasma etching or plasma deposition chamber. The semiconductor processing tool 100 may be a stand-alone tool, or the semiconductor processing tool 100 may be part of a cluster tool.

[0041] In the illustrated embodiment, the semiconductor processing tool 100 is shown as a RPS tool. The RPS semiconductor processing tool 100 may include a plasma chamber 130, a conduit 120, and a main processing chamber 110. The conduit 120 may fluidly couple the plasma chamber 130 with the main processing chamber 110.

[0042] For 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 act as a radio frequency (RF) or microwave source to initiate 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.

[0043] In one embodiment, the main processing chamber 110 may include a pedestal 105. In one embodiment, the pedestal 105 may include a clamping structure, such as an electrostatic clamp (ESC) structure. The pedestal 105 may also include a thermal control (e.g., heating or cooling) structure to control the temperature of a substrate 107 held by the pedestal 105. In one embodiment, the substrate 107 may be any substrate suitable for semiconductor processing operations. For example, the substrate 107 may be a semiconductor wafer, such as a silicon wafer, but other substrate materials may also be used. An exhaust device (not shown) may also be provided in the main processing chamber 110.

[0044] In one embodiment, the laser absorption spectroscopy tool may include a laser source 141 and a detector 142. The laser source 141 may be coupled to a first window 143 through a sidewall of the conduit 120, and the detector 142 may be coupled to a second window 144 through a sidewall of the conduit 120. In one embodiment, the laser source 141 and the detector 142 may be closer to the main processing chamber 110 than the plasma chamber 130. Such an embodiment may result in a measured species concentration that is closer to the species concentration that interacts with the substrate 107.

[0045] In one embodiment, laser light 145 transmitted by a laser source 141 passes through the volume of the pipe 120 and is optically coupled to a detector 142. In one embodiment, the laser source 141 can be a laser of any suitable wavelength suitable for laser absorption spectroscopy. For example, according to one embodiment, a 1278 nanometer laser source 141 can be used. The detector 142 can be any type of optical detector. For example, the detector 142 can be a charge coupled device (CCD).

[0046] Reference now Figure 1C , according to an additional embodiment, a schematic cross-sectional view of a semiconductor processing tool 100 is shown. The semiconductor processing tool 100 may include any type of plasma processing tool. For example, the semiconductor processing tool 100 may be a plasma etching or plasma deposition chamber. The semiconductor processing tool 100 may be a stand-alone tool, or the semiconductor processing tool 100 may be part of a cluster tool.

[0047] In the illustrated embodiment, the semiconductor processing tool 100 is shown as a RPS tool. The RPS semiconductor processing tool 100 may include a plasma chamber 130, a conduit 120, and a main processing chamber 110. The conduit 120 may fluidly couple the plasma chamber 130 and the main processing chamber 110.

[0048] For 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 act as a radio frequency (RF) or microwave source to initiate 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.

[0049] In one embodiment, the main processing chamber 110 may include a pedestal 105. In one embodiment, the pedestal 105 may include a clamping structure, such as an electrostatic clamp (ESC) structure. The pedestal 105 may also include a thermal control (e.g., heating or cooling) structure to control the temperature of a substrate 107 secured by the pedestal 105. In one embodiment, the substrate 107 may be any substrate suitable for semiconductor processing operations. For example, the substrate 107 may be a semiconductor wafer, such as a silicon wafer, although other substrate materials may also be used. An exhaust device (not shown) may also be provided in the main processing chamber 110.

[0050] In one embodiment, the laser absorption spectroscopy tool may include a laser source 141 and a detector 142. The laser source 141 may be coupled to a first window 143 through a sidewall of the main processing chamber 110, and the detector 142 may be coupled to a second window 144 through a sidewall of the main processing chamber 110. In one embodiment, the laser source 141 and the detector 142 may be relatively close to the substrate 107. For example, the laser 145 may be about 10 millimeters or less from the substrate 107. In a particular embodiment, the laser 145 may be about 5 millimeters or less from the substrate 107. Such an embodiment may allow the measured species concentration to be closer to the species concentration that actually interacts with the substrate 107.

[0051] In one embodiment, laser light 145 propagated by laser source 141 passes through the volume of main processing chamber 110 and is optically coupled to detector 142. In one embodiment, laser source 141 can be a laser source of any suitable wavelength suitable for laser absorption spectroscopy. For example, according to one embodiment, a 1278 nanometer laser source 141 can be used. Detector 142 can be any type of optical detector. For example, detector 142 can be a CCD element.

[0052] Reference now Figure 2, a schematic cross-sectional view of a semiconductor processing tool 200 is shown according to one embodiment. In one embodiment, the semiconductor processing tool 200 can be any plasma chamber, such as a plasma etching chamber or a plasma film deposition chamber. In contrast to the RPS embodiment described above, according to one embodiment, the semiconductor processing tool 200 can be a standard plasma tool. That is, the plasma 215 is generated in the same volume as the substrate 207.

[0053] The plasma 215 can be initiated using an RF or microwave source coupled to a lid 211 of the chamber 210. The lid 211 can include conductive features that couple microwave or RF signals to the process gas within the chamber 210 to initiate the plasma 215. In one embodiment, the lid 211 can also be a gas showerhead. That is, a gas (e.g., a process gas, an inert gas, etc.) can flow into the chamber 210 through the lid 211. For simplicity, the gas passage through the lid 211 is omitted. In addition, in some embodiments, the gas can also flow into the chamber 210 through a surface other than the lid 211.

[0054] In one embodiment, a pedestal 205 may be provided in the chamber 205. In one embodiment, the pedestal 205 may include a clamping structure, such as an ESC structure. The pedestal 205 may also include a thermal control (e.g., heating or cooling) structure to control the temperature of a substrate 207 held by the pedestal 205. In one embodiment, the substrate 207 may be any substrate suitable for semiconductor processing operations. For example, the substrate 207 may be a semiconductor wafer, such as a silicon wafer, but other substrate materials may also be used. An exhaust device (not shown) may also be provided in the processing chamber 210.

[0055] In one embodiment, the laser absorption spectroscopy tool may include a laser source 241 and a detector 242. The laser source 241 may be coupled to a first window 243 through a sidewall of the processing chamber 210, and the detector 242 may be coupled to a second window 244 through a sidewall of the processing chamber 210. In one embodiment, the laser source 241 and the detector 242 may be relatively close to the substrate 207. For example, the laser 245 may be about 10 millimeters or less from the substrate 207. In a particular embodiment, the laser 245 may be about 5 millimeters or less from the substrate 207. Such an embodiment may allow the measured species concentration to be closer to the species concentration that actually interacts with the substrate 207.

[0056] In one embodiment, laser light 245 is transmitted from laser source 241 through the volume of processing chamber 210 and optically coupled to detector 242. In one embodiment, laser source 241 can be any suitable wavelength laser suitable for laser absorption spectroscopy. For example, according to one embodiment, a 1278 nm laser source 241 can be used. Detector 242 can be any type of optical detector. For example, detector 242 can be a CCD.

[0057] Reference now Figure 3A FIG. 10 shows a graph of laser absorption versus wavelength according to one embodiment. In the graph shown, a plurality of different gas flow rates are shown. 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 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 percentages. Now referring to Figure 3B , according to one embodiment, shows a graph of species concentration (i.e., partial pressure) versus gas flow rate. In the specific example of NF3 gas, the partial pressure may be that of the HF species. As shown, higher gas flow rates correspond to higher species concentrations. By Figure 3A and Figure 3B By combining the plots in , the percent laser absorption can be used to calculate the concentration of species in a given treatment.

[0058] Reference now Figure 4A , according to one embodiment, a graph of laser absorption versus wavelength is shown. In the graph shown, a number of different power delivery levels are shown. In one embodiment, power delivery may refer to the power delivered to the plasma of the chamber. In one embodiment, the delivered power may be in the range of from 310W to 415W, although lower and higher powers may also be used. As shown, higher delivered powers correspond to higher absorption percentages. Now referring to Figure 4B , according to one embodiment, shows a graph of species concentration (i.e., partial pressure) versus delivered power. As shown, higher delivered power corresponds to higher species concentration. Figure 4A and Figure 4B The percentage of laser absorption can be used to calculate the concentration of species in a given treatment.

[0059] exist Figures 3A to 4BIn the example of gas flow rate and delivered power, laser absorption spectroscopy is used to illustrate how it is used to determine species concentration. However, it should be understood that other plasma parameters can also be used to change the species concentration measured by the laser absorption spectroscopy tool. For example, the frequency of the plasma, the pressure of the processing chamber, and the temperature of the processing chamber can also be changed to change the species concentration in the chamber. In addition, although the example of HF is provided as the measured substance concentration, it is also conceivable to monitor other species or species combinations. For example, the concentration of one or more of HF, O, Ar, N, NH, NH2, NH3, F, He, H, H2, F2, NF, NF2, NF3, 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.

[0060] Reference now Figure 5 , a cross-sectional view of a semiconductor processing tool 500 is shown according to one embodiment. In one embodiment, the semiconductor processing tool 500 may be Figure 1A 520. For example, the plasma chamber 530 can be fluidically coupled to the main processing chamber 510 via a conduit 520. The main processing chamber 510 can include a susceptor 505 and a substrate 507 located on the susceptor 505. In one embodiment, a plasma 515 can be initiated in the plasma chamber 530. In addition, a laser absorption spectroscopy tool can be included, which includes a laser source 541 and a detector 542. The laser source 541 and the detector 542 can be optically coupled to each other in the conduit 520 via windows 543 and 544. The laser light 542 can be transmitted from the laser source 541 to the detector 542 between the windows 543 and 544.

[0061] exist Figure 5 550. The plasma controller 550 may be used to control one or more parameters of the plasma produced in the plasma chamber 530. For example, the plasma controller 550 may control the gas flow rate, the power delivered to the plasma, the frequency of the plasma, the pressure in the plasma chamber 530, and the temperature of the plasma chamber 530. The feedback loop 555 may provide a closed-loop control solution to monitor and control the concentration of species in a semiconductor processing tool. Therefore, control of processing conditions may be achieved without relying on historical data and / or dummy substrates.

[0062] Reference now Figure 6 , according to one embodiment, a process flow diagram of process 660 is shown. In one embodiment, process 660 can be used to control species concentration within a semiconductor processing chamber.

[0063] In one embodiment, process 660 may begin with operation 661, which includes initiating a plasma in a process chamber. In one embodiment, the process chamber may be similar to any process chamber described in more detail herein. For example, the process chamber may be an RPS chamber or a standard plasma chamber.

[0064] In one embodiment, process 660 may continue with operation 662, which includes propagating laser light through the chamber using a laser source. The laser source may be any suitable wavelength suitable for laser absorption spectroscopy, and in some embodiments may even include multiple wavelengths. As the laser light passes through the chamber, the laser light interacts with the species, and power from the laser light is absorbed.

[0065] In one embodiment, process 660 may continue with operation 663, which includes detecting the laser light with a detector after the laser light passes through the chamber. In one embodiment, the detector may be a CCD or any other optical detector architecture. In one embodiment, the detector may be opposite the laser source. Thus, the laser light may propagate in a straight line from the laser source across the chamber to the detector. The laser source and the detector may be located outside the window through the side wall of the chamber.

[0066] In one embodiment, process 660 may continue with operation 664, which includes detecting absorption of the laser light with a detector after the laser light passes through the chamber. In one embodiment, the amount of absorption of the laser light may be correlated to the density of the species in the chamber.

[0067] In one embodiment, process 660 may continue with operation 665, which includes controlling the plasma within the processing chamber in response to the detected laser absorption. For example, feedback from the laser absorption may be used to change one or more plasma parameters, such as gas flow rate, power delivered to the plasma, frequency of the plasma, pressure of the processing chamber, and temperature of the processing chamber.

[0068] As described above, not all free radical species or other species can be measured directly by the laser absorption spectroscopy process. Therefore, the disclosed embodiments further include a measurement line that can convert free radicals (or species) into species that can be measured by laser absorption spectroscopy processing. In some embodiments, the measurement line is parallel to the main processing chamber fluid. In other embodiments, the measurement line can be directly coupled to the main processing chamber. In another embodiment, the measurement line is located downstream of the main processing chamber. In one embodiment, the measurement line can 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.

[0069] Reference now Fig. 7A, a schematic diagram of a semiconductor processing tool 700 is shown according to one embodiment. In one embodiment, the semiconductor processing tool 700 may include a remote plasma source 730. Although an embodiment with a remote plasma source 730 is shown, it should be understood that any device capable of generating free radicals may be used in place of the remote plasma source 730.

[0070] In one embodiment, the remote plasma source 730 can be fluidly coupled to the main processing chamber 710. The main processing chamber 710 can include a fixture or the like for holding a substrate (not shown). The main processing chamber can be used as a deposition chamber, an etching chamber, or any other chamber for semiconductor processing including free radical species.

[0071] In one embodiment, the main processing chamber 710 may be fluidly coupled to a pump 713. The pump 713 provides a low pressure environment (e.g., a vacuum environment) to the main processing chamber 710. A chamber throttle valve 711 and a chamber isolation valve 712 may be provided between the pump 713 and the chamber 710, which are common in semiconductor manufacturing tools.

[0072] In one embodiment, a pressure P may be provided between the remote plasma source 730 and the main chamber 710. U A chamber pressure P may be provided in the chamber 710 CH , and pump pressure can be provided at pump 713 In one embodiment, the pressure P U Greater than pressure P CH , and the pressure P CH Greater than pressure

[0073] In one embodiment, the measurement line may be provided in parallel with the chamber 710. That is, the inlet of the measurement line may be located upstream of the chamber 710, and the outlet of the measurement line may be located downstream of the chamber 710. For example, the inlet of the measurement line may be located between the remote plasma source 730 and the chamber 710, and the outlet of the measurement line may be located between the isolation valve 712 and the pump 713.

[0074] In one embodiment, the measurement line is configured to modify the free radicals (or species) generated by the remote plasma source 730 to make the free radicals (or species) compatible with laser absorption spectroscopy. For example, a controlled chemical reaction with the free radicals (or species) can be performed to produce new species that can be detected by laser absorption spectroscopy. Then, the measurement of the new species can be used to calculate the concentration or flux of the original free radical (or species).

[0075] In one embodiment, the measurement line may include a reaction unit 731. The reaction unit 731 may be a chamber in which free radicals react to form new species. Therefore, in some cases, the reaction unit 731 may be referred to as a reaction chamber 731. In one embodiment, the reaction unit 731 may receive free radicals as a first input, and the reaction unit 731 may receive a first gas as a second input. The free radicals and the first gas may react with each other to form a second gas. The second gas contains species that can be measured using laser absorption spectroscopy. A more detailed description of the reaction unit 731 is provided below.

[0076] In a particular embodiment, the free radical or species of interest may be fluorine. In this embodiment, the first gas may include H2, C X H Y X Z (wherein X is F or Cl), C X H Y , NH3, B2H6, and H2O. The reaction between fluorine and the first gas may produce HF, which may be measured by laser absorption spectroscopy. In another embodiment, the free radical or species of interest may be chlorine. In this embodiment, the first gas may contain H2, C X H Y X Z (wherein X is F or Cl), C X H Y , NH3, B2H6, and H2O. The reaction between chlorine and the first gas may produce HCl, which may be measured by laser absorption spectroscopy. In another embodiment, the free radical or species of interest may be oxygen. In this embodiment, the first gas may contain C X H Y , H2, NH3, or B2H6. The reaction between oxygen and the first gas may produce one or more of carbon monoxide (CO), carbon dioxide (CO2), and H2O, which may be measured by laser absorption spectroscopy. In another embodiment, the free radical or species of interest may be hydrogen. In this case, the first gas may contain 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)The reaction between hydrogen and the first gas may produce one or both of HF and / or HCl, which may be measured by laser absorption spectroscopy. The free radicals may also include sulfur, phosphorus, or silicon. The reaction may also produce NH, NH2, NH3, HS, H2S, PH, PH2, PH3, C X H Y One or more of SiH, SiH2, SiH3, and SiH3, which can be measured by laser absorption spectroscopy. Although several examples of material classes are shown, it should be understood that any free radical or species that can react to form a new species that can be measured by laser absorption spectroscopy can be used in accordance with the disclosed embodiments.

[0077] In one embodiment, the measurement line may further include a measurement unit 732. The measurement unit 732 may be a chamber in which the second gas is measured using laser absorption spectroscopy. Therefore, in some cases, the measurement unit 732 may be referred to as a measurement chamber 732 or an absorption chamber 732. In one embodiment, the measurement unit 732 may receive the second gas as an input. Then, the second gas is measured using laser absorption spectroscopy. For example, a pair of windows facing each other may allow the laser to pass through the measurement unit 732 and be detected by the light detector. A more detailed description of the measurement unit 732 is provided below.

[0078] In one embodiment, the measuring unit 732 may have a pressure P A In one embodiment, the pressure P A Less than pressure P U And greater than the pressure By controlling the throttle valve 733 downstream of the measuring unit 732, the pressure P A Controlled by P U and In an additional embodiment, a mass flow meter (MFM) 734 may be provided between the throttle valve 733 and the pump 713 .

[0079] Reference now Figure 7B , a schematic diagram of a semiconductor processing tool 700 is shown, according to an additional embodiment. Figure 7B A semiconductor processing tool 700 and Fig. 7A 700 is substantially similar to the semiconductor processing tool 700 in FIG. 700 , except for the fluid coupling of the measurement line. The upstream side of the measurement line is coupled to the chamber 710, rather than being parallel to the main processing chamber fluid. Therefore, the free radical flux 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 be used. The measurement line can have a downstream end coupled to a gas line between an isolation valve 712 and a pump 713.

[0080] Reference now Figure 7C , according to an additional embodiment, a schematic diagram of a semiconductor processing tool 700 is shown. In one embodiment, Figure 7C A semiconductor processing tool 700 and Fig. 7A 700 is substantially similar to the semiconductor processing tool 700 in FIG. 700 , except for the fluid coupling of the measurement line. The upstream side of the measurement line is coupled to the gas pipeline between the main processing chamber 710 and the throttle valve 711, and is not parallel to the main processing chamber fluid. Therefore, the free radical flux leaving the chamber can be determined by the measurement line. In the embodiment shown, 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 can have a downstream end coupled to the gas pipeline between the isolation valve 712 and the pump 713.

[0081] exist Figures 7A to 7C , three different measurement line architectures are shown. However, it should be understood that in some embodiments, these three different measurement line architectures can be combined with each other. For example, two or more different measurement lines can be provided in a single semiconductor processing tool 700. That is, a single semiconductor processing tool 700 can include a first measurement line having an input terminal located between a plasma source and a main chamber, a second measurement line having an input terminal located in the main chamber, and a third measurement line having an input terminal located downstream of the main chamber.

[0082] Reference now Fig. 8A , according to one embodiment, a schematic cross-sectional view of a reaction unit 831 that can be used in a semiconductor processing tool is shown. In one embodiment, the reaction unit 831 can include a chamber 821. The chamber can be fluidly coupled to a main processing pipeline of a plasma processing tool. For example, the reaction unit 831 can be fluidly coupled between a remote plasma source and a main chamber, fluidly coupled to a main chamber chamber, or fluidly coupled to a downstream side of the main chamber, similar to Figures 7A to 7C The embodiment shown in FIG.

[0083] In one embodiment, the chamber 821 may have multiple gas feed lines. Feed line 822 may be used to guide free radicals 827 from a remote plasma source (or other source of free radicals or species) into the chamber 821. In one embodiment, a second feed line 823 is used to guide a first gas 828 into the chamber 821. The flow rate of the first gas 828 may be controlled by a mass flow controller (not shown). Thus, a specific amount of the first gas 828 may flow into the chamber 821 to react with the species 827 to form a second gas 829. In one embodiment, a third feed line 824 may be used as an outlet of the chamber 821. The second gas 829 may leave the chamber 821 via the third feed line 824. In one embodiment, the second gas 829 may include species to be measured. Additional embodiments have a second gas 829 that includes other species that are part of the reaction between the free radicals and the first gas but are not intended to be measured.

[0084] In one embodiment, the chamber 821 may also include a thermometer 825 or any other device capable of measuring temperature. The thermometer 825 may be used to control the temperature of the chamber 821. For example, the chamber 821 may be heated or cooled to drive a specific reaction. In addition, the chamber 821 may also include a converter 826. The converter 826 may be connected to a throttle valve (e.g. Fig. 7A The throttle valve 733 is used in combination to control the pressure within the chamber 821.

[0085] Reference now Figure 8B , a schematic diagram of a measurement chamber 832 is shown according to an embodiment. In an embodiment, the measurement unit 832 may include a chamber 836. The chamber 836 may be fluidically coupled to the chamber 821 via the third feed line 824. Thus, a second gas 829 is caused to flow into the chamber 836. The second gas 829 flows through the chamber 821 and exits as a gas 835. In an embodiment, the gas 835 may be substantially similar to the second gas 829. That is, there may not be any further reaction within the chamber 836.

[0086] In one embodiment, the measurement unit 832 may further include a pair of windows 837 and 838. The windows 837 and 838 may be located on opposite sides of the chamber 836. A light source 841 (e.g., a laser) may be provided near the window 837, and a light detector 842 may be provided near the window 838. The light source 841 is configured to emit a light 845 through the windows 837 and 838, and the light source 841 is optically coupled to the light detector 842. The light 845 is partially absorbed by the second gas 829. The light detector 842 detects the amount of absorption of the light 845, so that the concentration of the measured species can be determined. The concentration of the measured species can then be used to calculate the concentration or flux of the radical species flowing into the measurement line.

[0087] In one embodiment, chamber 836 may also include a thermometer 825 or any other device capable of measuring temperature. The thermometer 825 may be used to control the temperature of chamber 836. For example, chamber 836 may be heated or cooled. In addition, chamber 836 may include a converter 826. Converter 826 may be coupled to a throttle valve (e.g., Fig. 7A Used in conjunction with the throttle valve 733) to control the pressure within chamber 836.

[0088] Reference now Fig. 9 , according to one embodiment, a schematic diagram of a combined reaction unit 931 and a measurement unit 932 is shown. That is, the unit 931 / 932 may include a single chamber 936, rather than having different chambers (such as Fig. 8A and Figure 8B ). Thus, both the chemical reaction (conversion of the free radical species to a measurable species) and the absorption measurement can be provided in the same chamber 936.

[0089] In one embodiment, the free radical species 927 may flow into the chamber 936. In one embodiment, the first gas 928 also flows into the chamber 936. The amount of the first gas 928 flowing into the chamber 936 may be controlled by a mass flow controller (not shown). The first gas 928 and the free radical species 927 may react to form a second gas 935 that flows out of the chamber 936.

[0090] In addition, a laser absorption spectroscopy framework is provided on the chamber 936. For example, a pair of windows 937 and 938 can be located on opposite sides of the chamber 936. A light source 941 (e.g., a laser) can be provided near the window 937, and a light detector 942 can be provided near the window 938. The light source 941 is configured to emit light 945 through the windows 937 and 938, and the light source 941 is optically coupled to the light detector 942. The light 945 is partially absorbed by the second gas 935. The light detector 942 detects the amount of absorption of the light 945, thereby determining the concentration of the measured species. The concentration of the measured species can then be used to calculate the concentration or flux of the free radical species 927 flowing into the chamber 936.

[0091] In one embodiment, chamber 936 may also include a thermometer 925 or any other device capable of measuring temperature. The thermometer 925 may be used to control the temperature of chamber 936. For example, chamber 936 may be heated or cooled to drive a particular reaction. In addition, chamber 936 may include a converter 926. Converter 926 may be coupled to a throttle valve (e.g., Fig. 7A Used in conjunction with the throttle valve 733) in order to control the pressure within the chamber 936.

[0092] Reference now Fig.10, a process flow diagram of a process 1080 for measuring radical flux in a semiconductor processing tool is shown according to an embodiment. In an embodiment, the process 1080 can be implemented using any of the semiconductor processing tools described above including a measurement line.

[0093] In one embodiment, processing 1080 may start from operation 1081, which includes generating free radicals using a plasma source. In some embodiments, free radicals may be generated by a remote plasma source. However, other plasma sources may also be used depending on the configuration of the semiconductor processing tool. In addition, although referred to as free radicals, it should be understood that other species may also be generated in operation 1081. In a particular embodiment, the free radicals (or species) generated are free radicals (or species) that cannot be directly measured using laser absorption spectroscopy. That is, in order to measure free radicals or species, a large amount of equipment and engineering expenditure is required. For example, free radicals may include one or more of fluorine, oxygen, chlorine, sulfur, phosphorus, silicon, and hydrogen.

[0094] In one embodiment, process 1080 may continue with operation 1082, which includes shunting a sample of free radicals to a sampling line. In one embodiment, the free radicals may be shunted to the sampling line before reaching the main processing chamber. In other embodiments, the free radicals are shunted to the sampling line after reaching the main processing chamber. In another embodiment, the free radicals are shunted to the sampling line after passing through the main processing chamber. In one embodiment, the downstream side of the sampling line may be coupled to a line before a pump of the semiconductor processing tool. For example, the downstream side of the sampling line may be provided between an isolation valve and a pump.

[0095] In one embodiment, process 1080 may continue with operation 1083, which includes reacting the free radical with the first species to form a second species. In a particular embodiment, the free radical or species of interest may be fluorine. In such embodiments, the first species may include H2, C X H Y X Z (wherein X is F or Cl), C X H Y , NH3, B2H6 and H2O. The reaction between F and the first species may produce a gas including a second species HF, which can be measured by laser absorption spectroscopy. In another embodiment, the free radical or species of interest may be chlorine. In this embodiment, the first species may include H2, C X H Y X Z (wherein X is F or Cl), C X H Y, NH3, B2H6, and H2O. The reaction between chlorine and the first species may produce a gas including a second species, hydrogen chloride (HCl), which may be measured by laser absorption spectroscopy. In another embodiment, the free radical or species of interest may be oxygen. In this embodiment, the first species may include C X H Y , H2, NH3, and B2H6. The reaction between oxygen and the first species may produce a gas including two species, the second species including one or more of CO, CO2, and H2O, which can be measured by laser absorption spectroscopy. In another embodiment, the free radical or species of interest may be hydrogen. In such embodiments, the first species may include 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) The reaction between hydrogen and the first species may produce a gas including a second species, the second species including one or more of hydrogen fluoride and hydrogen chloride, which can be measured by laser absorption spectroscopy. Although several examples of material classes are shown, it should be understood that any free radical or species that can react to form a new species that can be measured by laser absorption spectroscopy can be used according to the embodiments described herein.

[0096] In one embodiment, process 1080 may continue with operation 1084, which includes measuring a second species in an absorption chamber. In one embodiment, the absorption chamber may be similar to any of the measurement units or measurement chambers described in more detail above. For example, the absorption chamber may include a first window and a second window located on opposite sides of the chamber. A light source (e.g., a laser) may emit light through the first window and the second window. The light source is optically coupled to a light detector to determine a level of absorption provided by the second species. In some embodiments, the absorption chamber may be a different chamber from where the chemical reaction occurs. In other embodiments, the absorption chamber may be the same chamber as where the chemical reaction occurs.

[0097] Reference now Fig.11A and Fig. 11B , a graph illustrating the relationship between the measured partial pressure and the etching rate is shown. Fig.11AAs shown in Figure 1, the HF partial pressure increases to a maximum of about 125W, then decreases, and then increases again to 175W. Similarly, the etch rate over the power range also shows the same decrease and subsequent increase. That is, the measurement of partial pressure is a mirror image of the etch rate. In addition, as Fig. 11B As shown, there is a strong linear trend between the etch rate data and the HF partial pressure data. Therefore, knowledge of the HF partial pressure can be directly correlated to the expected etch rate on the substrate.

[0098] Reference now Fig.12 , a block diagram of an example computer system 1200 of a processing tool is shown, according to one embodiment. In one embodiment, the computer system 1200 is coupled to the processing tool and controls the processing in the processing tool. The computer system 1200 can be connected (e.g., networked) to other machines in a local area network (LAN), an intranet, an 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), a tablet PC, a set-top box (STB), a personal digital assistant (PDA), a cellular phone, a network appliance, a server, a network router, a switch or a bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be performed by the machine. Further, while a single machine is illustrated with respect to computer system 1200, the term "machine" shall also be taken to include any collection of machines (e.g., computers) that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies described herein.

[0099] The computer system 1200 may include a computer program product or software 1222 having a non-transitory machine-readable medium having instructions stored thereon, which can be used to program the computer system 1200 (or other electronic device) to perform processing according to an embodiment. Machine-readable media include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer). For example, machine-readable (e.g., computer-readable) media include machine (e.g., computer) readable storage media (e.g., read-only memory (readonly memory; "ROM"), random access memory (random access memory; "RAM"), magnetic disk storage media, optical storage media, flash memory devices, etc.), machine (e.g., computer) readable transmission media (electrical, optical, acoustic or other forms of propagated signals (e.g., infrared signals, digital signals, etc.), etc.

[0100] In one embodiment, the computer system 1200 includes a system processor 1202, a main memory 1204 (e.g., read-only memory (ROM), flash memory, dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM) or Rambus DRAM (RDRAM), etc.), 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.

[0101] The system processor 1202 represents one or more general-purpose processing devices, such as a microsystem processor, a central processing unit, or the like. More specifically, the system processor may be a complex instruction set computing (CISC) microsystem processor, a reduced instruction set computing (RISC) microsystem processor, a very long instruction word (VLIW) microsystem processor, a system processor implementing other instruction sets, or a system processor implementing a combination of instruction sets. The system processor 1202 may 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), a network system processor, or the like. The system processor 1202 is configured to execute processing logic 1226 for performing the operations described herein.

[0102] 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 (e.g., a mouse), and a signal generating device 1216 (e.g., a speaker).

[0103] The secondary memory 1218 may include a machine-accessible storage medium 1232 (or more specifically, a computer-readable storage medium) on which is stored one or more sets of instructions (e.g., software 1222) that embody any one or more of the methods or functions described herein. The software 1222 may also reside, in whole or in part, within the main memory 1204 and / or within the system processor 1202 during execution of the software 1222 by the computer system 600, the main memory 1204 and the system processor 1202 also constituting machine-readable storage media. The software 1222 may also be sent 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.

[0104] Although the machine-accessible storage medium 2332 is shown as a single medium in the exemplary embodiment, the term "machine-readable storage medium" should be considered to include a single medium or multiple media (e.g., a centralized or distributed database, and / or associated cache memory and servers) storing one or more sets of instructions. The term "machine-readable storage medium" should also include any medium that can store or encode a set of instructions for execution by a machine and cause the machine to perform any one or more methods. Therefore, the term "machine-readable storage medium" should be considered to include, but is not limited to, solid-state memory and optical and magnetic media.

[0105] In the foregoing specification, specific exemplary embodiments have been described. It will be apparent that various modifications may be made thereto without departing from the scope of the following claims. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.

Claims

1. A semiconductor processing tool comprising: Chamber; a susceptor configured to fix a substrate within the chamber; a plasma source above the susceptor; a light source coupled to the chamber; as well as A detector is coupled to the chamber opposite the light source, wherein the detector is configured to be optically coupled to the light source.

2. The semiconductor processing tool of claim 1 , further comprising: a first optical window extending through the chamber and adjacent to the light source; as well as A second optical window is disposed through the chamber adjacent to the detector.

3. The semiconductor processing tool of claim 1, wherein the light source and the detector are positioned such that light propagating from the light source to the detector is approximately 10 millimeters or less from the pedestal.

4. The semiconductor processing tool of claim 1, wherein the plasma source is a remote plasma source.

5. The semiconductor processing tool of claim 4, wherein the chamber includes a conduit coupling the plasma source to a lower portion of the chamber.

6. The semiconductor processing tool of claim 5, wherein a distance between the light source and the plasma source is less than a distance between the light source and the lower portion of the chamber.

7. The semiconductor processing tool of claim 5, wherein a distance between the light source and the plasma source is greater than a distance between the light source and the lower portion of the chamber.

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

9. The semiconductor processing tool of claim 8, wherein the laser absorption spectroscopy is configured to monitor species including one or more of HF, O, Ar, N, F, He, H, H2, F2, NF, NF2, NF3, Cl, and Si.

10. The semiconductor processing tool of claim 1, wherein the semiconductor processing tool is a deposition tool or an etching tool.

11. A method of processing a substrate in a semiconductor processing tool, comprising: initiating a plasma in a processing chamber; propagating light through the chamber using a light source; After the light passes through the chamber, detecting the light with a detector; detecting absorption of the light with the detector after the light passes through the chamber; and The plasma in the processing chamber is controlled in response to the detected absorption of the light.

12. The method of claim 11, wherein the processing chamber is a remote plasma source (RPS) processing chamber.

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

14. The method of claim 11, wherein a distance between the light source and the substrate within the chamber is approximately 10 millimeters or less.

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

16. The method of claim 15, wherein the species concentration comprises one or more of HF, O, Ar, N, F, He, H, H2, F2, NF, NF2, NF3, Cl, and Si.

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

18. A semiconductor processing tool comprising: a remote plasma chamber; a processing chamber, wherein the remote plasma chamber is coupled to the processing chamber via a conduit; a susceptor configured to support a substrate within the processing chamber; a laser source coupled to a first window in the semiconductor processing tool; as well as A detector is coupled to a second window in the semiconductor processing tool, wherein the laser source and the detector are configured to be optically coupled to each other.

19. The method of claim 18, wherein the first and second viewing windows are provided through a side wall of the conduit.

20. The method of claim 18, wherein the first viewing window and the second viewing window are provided through a sidewall of the processing chamber.

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