Plasma processing system, device for detecting end point of plasma processing, and method for detecting end point of plasma processing

Abstract

This plasma processing system comprises: a chamber; a substrate support unit disposed in the chamber; a gas supply unit configured to supply a processing gas into the chamber; a plasma generation unit configured to generate plasma from the processing gas in the chamber and execute plasma processing on a substrate on the substrate support unit; a luminescence intensity measurement unit configured to measure the luminescence intensity of a specific wavelength component included in the plasma generated in the chamber during the plasma processing; an electron density measurement unit configured to measure the electron density of the plasma generated in the chamber during the plasma processing; and an end point detection unit configured to detect the end point of the plasma processing on the basis of a change over time in the correlation between the luminescence intensity and the electron density that are measured at the same timing.

Description

Plasma Processing System, Apparatus for Detecting End Point of Plasma Processing, and Method for Detecting End Point of Plasma Processing

[0001] The present disclosure relates to a plasma processing system, an apparatus for detecting the end point of plasma processing, and a method for detecting the end point of plasma processing.

[0002] For example, Patent Document 1 discloses an etching apparatus including a substrate electrode that applies high-frequency power to a substrate to be subjected to an etching process, and a source electrode for generating plasma supplied onto the substrate electrode. Patent Document 1 discloses that the etching apparatus is provided with electron density control means for controlling the high-frequency power applied to the source electrode so that the electron density in the plasma supplied onto the substrate electrode becomes a predetermined set value.

[0003] Japanese Patent Application Laid-Open No. 2004-128236

[0004] The present disclosure provides a technique for suppressing the influence of electron density on the emission intensity inside a plasma processing chamber.

[0005] According to one aspect of the present disclosure, there is provided a plasma processing system including a chamber, a substrate support portion disposed in the chamber, a gas supply portion configured to supply a processing gas into the chamber, a plasma generation portion configured to generate plasma from the processing gas in the chamber and perform plasma processing on a substrate on the substrate support portion, an emission intensity measurement portion configured to measure the emission intensity of a specific wavelength component included in the plasma generated in the chamber during the plasma processing, an electron density measurement portion configured to measure the electron density of the plasma generated in the chamber during the plasma processing, and an end point detection portion configured to detect the end point of the plasma processing based on a temporal change in the correlation between the emission intensity and the electron density measured at the same timing.

[0006] The present disclosure provides a technique for suppressing the influence of electron density on the emission intensity inside a plasma processing chamber.

[0007] Figure 1 is a diagram illustrating the configuration of the plasma processing system according to this embodiment. Figure 2 is a diagram illustrating the relationship between emission intensity and electron density during plasma processing in the plasma processing system according to this embodiment. Figure 3 is a diagram illustrating the emission intensity during plasma processing corrected for fluctuations due to electron density in the plasma processing system according to this embodiment. Figure 4 is a diagram illustrating a first example of processing in the plasma processing system according to this embodiment. Figure 5 is a diagram illustrating a second example of processing in the plasma processing system according to this embodiment. Figure 6 is a diagram illustrating a third example of processing in the plasma processing system according to this embodiment.

[0008] Hereinafter, embodiments for carrying out this disclosure will be described with reference to the drawings. In this specification and the drawings, substantially identical components are denoted by the same reference numerals to avoid redundant explanations. For ease of understanding, the scale of the parts in the drawings may differ from that of the actual parts. In directions such as parallel, right angles, orthogonal, horizontal, vertical, up and down, and left and right, deviations are permitted to the extent that they do not impair the effect of the embodiment. The shape of the corners is not limited to right angles and may be rounded. Parallel, right angles, orthogonal, horizontal, and vertical may include substantially parallel, substantially right angles, substantially orthogonal, substantially horizontal, and substantially vertical.

[0009] The following describes an example of the configuration of a plasma processing system. Figure 1 is a diagram illustrating the configuration of a plasma processing system S, which is an example of a plasma processing system according to this embodiment. Figure 1 is a diagram illustrating an example of the configuration of a capacitively coupled plasma processing apparatus.

[0010] The plasma processing system S includes a capacitively coupled plasma processing apparatus 1 and a control unit 2. The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply system 30, an exhaust system 40, a light emission intensity measuring unit 50, and an electron density measuring unit 60. The plasma processing apparatus 1 also includes a substrate support unit 11 and a gas introduction unit. The gas introduction unit is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas introduction unit includes a shower head 13. The substrate support unit 11 is located inside the plasma processing chamber 10. The shower head 13 is located above the substrate support unit 11. In one embodiment, the shower head 13 constitutes at least a part of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the shower head 13, the side walls 10a of the plasma processing chamber 10, and the substrate support unit 11. The plasma processing chamber 10 has at least one gas supply port for supplying at least one processing gas to the plasma processing space 10s, and at least one gas outlet for discharging gas from the plasma processing space. The plasma processing chamber 10 is grounded. The shower head 13 and the substrate support portion 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0011] The substrate support portion 11 includes a main body portion 111 and a ring assembly 112. The main body portion 111 has a central region 111a for supporting the substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of a substrate W. The annular region 111b of the main body portion 111 surrounds the central region 111a of the main body portion 111 in a plan view. The substrate W is placed on the central region 111a of the main body portion 111, and the ring assembly 112 is placed on the annular region 111b of the main body portion 111 so as to surround the substrate W on the central region 111a of the main body portion 111. Therefore, the central region 111a is also called the substrate support surface for supporting the substrate W, and the annular region 111b is also called the ring support surface for supporting the ring assembly 112.

[0012] In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes a conductive member. The conductive member of the base 1110 can function as a lower electrode. The electrostatic chuck 1111 is placed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic chuck electrode 1111b placed within the ceramic member 1111a. The electrostatic chuck electrode 1111b is also called a clamping electrode. In one embodiment, the electrostatic chuck electrode 1111b is electrically connected or coupled to a chuck power supply. The chuck power supply may be a DC power supply or an AC power supply. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Furthermore, other members surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may have an annular region 111b. In this case, the ring assembly 112 may be placed on the annular electrostatic chuck or the annular insulating member, or it may be placed on both the electrostatic chuck 1111 and the annular insulating member. In addition, at least one bias electrode, which is electrically connected or coupled to the power supply 31 and / or power supply 32 described later, may be placed inside the ceramic member 1111a. In this case, at least one bias electrode functions as a lower electrode. Also, the conductive member of the base 1110 and the bias electrode inside the ceramic member 1111a may function as multiple lower electrodes. In one embodiment, the first voltage generation unit 32a, which functions as a voltage pulse generation unit described later, is electrically connected or coupled to the bias electrode inside the ceramic member 1111a, and the first RF generation unit 31a, described later, is electrically connected or coupled to the conductive member of the base 1110. Furthermore, the electrostatic chuck electrode 1111b may function as a lower electrode. Therefore, the substrate support portion 11 includes at least one lower electrode.

[0013] The ring assembly 112 includes one or more annular members. In one embodiment, the one or more annular members include one or more edge rings and at least one covering ring. The edge rings are formed of a conductive or insulating material, and the covering rings are formed of an insulating material.

[0014] The substrate support section 11 may also include a temperature control module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate to a target temperature. The temperature control module may include a heater, a heat transfer medium, a flow path 1110a, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path 1110a. In one embodiment, the flow path 1110a is formed within the base 1110, and one or more heaters are arranged within the ceramic member 1111a of the electrostatic chuck 1111. The substrate support section 11 may also include a heat transfer gas supply section configured to supply heat transfer gas to the gap between the back surface of the substrate W and the central region 111a.

[0015] The showerhead 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The showerhead 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and a plurality of gas inlet ports 13c. The processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s through the plurality of gas inlet ports 13c. The showerhead 13 also includes at least one upper electrode. In addition to the showerhead 13, the gas introduction unit may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the side wall 10a.

[0016] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one processing gas to the shower head 13 from a corresponding gas source 21 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may include one or more flow modulation devices that modulate or pulse the flow rate of at least one processing gas.

[0017] The power supply system 30 includes a power supply 31 that is electrically connected to or coupled to the plasma processing chamber 10. In one embodiment, the power supply 31 is electrically connected to or coupled to the plasma processing chamber 10 via at least one impedance matcher. The impedance matcher may be a mechanically controlled matcher or an electronically controlled matcher. The power supply 31 is configured to supply at least one RF (Radio Frequency) signal (RF power) to at least one lower electrode and / or at least one upper electrode. This generates plasma from at least one processing gas supplied to the plasma processing space 10s. Therefore, the power supply 31 can function as at least part of a plasma generation unit configured to generate plasma from one or more processing gases in the plasma processing chamber 10. In addition, by supplying a bias RF signal to at least one lower electrode, a bias potential is generated on the substrate W, and ionic components in the formed plasma can be drawn into the substrate W.

[0018] The power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation unit 31a is electrically connected or coupled to at least one lower electrode and / or at least one upper electrode and is configured to generate a source RF signal (source RF power) to generate plasma in the plasma processing space 10s. In one embodiment, the first RF generation unit 31a is electrically connected or coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matcher. In one embodiment, the source RF signal has a frequency in the range of 10 MHz to 150 MHz. In one embodiment, the first RF generation unit 31a may be configured to generate a plurality of source RF signals having different frequencies. One or more generated source RF signals are supplied to at least one lower electrode and / or at least one upper electrode.

[0019] The second RF generation unit 31b is electrically connected to or coupled to at least one lower electrode and is configured to generate a bias RF signal (bias RF power). In one embodiment, the second RF generation unit 31b is electrically connected to or coupled to at least one lower electrode via at least one impedance matcher. When the first RF generation unit 31a is electrically connected to or coupled to a lower electrode, the second RF generation unit 31b may be electrically connected to or coupled to the same lower electrode, or it may be electrically connected to or coupled to a different lower electrode. The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100 kHz to 60 MHz. In one embodiment, the second RF generation unit 31b may be configured to generate a plurality of bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one lower electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0020] The power supply system 30 may also include a power supply 32 that is electrically connected to or coupled to the plasma processing chamber 10. The power supply 32 includes a first voltage generation unit 32a and a second voltage generation unit 32b. In one embodiment, the first voltage generation unit 32a is electrically connected to or coupled to at least one lower electrode and is configured to generate a first voltage signal. The generated first voltage signal is applied to at least one lower electrode. In one embodiment, the second voltage generation unit 32b is electrically connected to or coupled to at least one upper electrode and is configured to generate a second voltage signal. The generated second voltage signal is applied to at least one upper electrode.

[0021] In various embodiments, the first and / or second voltage signals may be pulsed. In this case, the first voltage generation unit 32a and / or the second voltage generation unit 32b function as voltage pulse generation units configured to generate a sequence of voltage pulses. Thus, the sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. In one embodiment, the sequence of voltage pulses has multiple cycles, each cycle including a burst of voltage pulses in a first period and a constant reference voltage in a second period. That is, in the sequence of voltage pulses, bursts of voltage pulses are repeated. The absolute value of the voltage level of the voltage pulse is greater than the absolute value of the voltage level of the reference voltage. The voltage pulse may have an arbitrary waveform having a rectangle, trapezoid, triangle, or a combination thereof, and the arbitrary waveform may change over time. The voltage pulse may have positive polarity or negative polarity. The sequence of voltage pulses may also include one or more positive voltage pulses and one or more negative voltage pulses within one cycle. The first voltage generation unit 32a and the second voltage generation unit 32b may be provided in addition to the power supply 31, and the first voltage generation unit 32a may be provided in place of the second RF generation unit 31b.

[0022] The exhaust system 40 may be connected to, for example, a gas outlet 10e located at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure regulating valve regulates the pressure in the plasma processing space 10s. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0023] The emission intensity measuring unit 50 measures the emission intensity of the plasma in the plasma processing chamber 10. The emission intensity measuring unit 50 measures the emission intensity of wavelengths (emission intensity of specific wavelength components) caused by by-products or processing gases in the plasma processing inside the plasma processing chamber 10. The emission intensity measuring unit 50 includes, for example, a spectrometer. The emission intensity measuring unit 50 measures the emission intensity of light at predetermined wavelengths in order to measure the emission intensity of an atom or molecule to be measured. The emission intensity measuring unit 50 is installed, for example, on the side wall 10a of the plasma processing chamber 10. The emission intensity measuring unit 50 measures the emission intensity of the plasma inside the plasma processing chamber 10 through a window provided in the side wall 10a of the plasma processing chamber 10. The control unit 2 is configured to acquire the measurement results from the emission intensity measuring unit 50, for example, via Ethernet (registered trademark). The emission intensity measuring unit 50 may be directly attached to the plasma processing chamber 10, or it may be installed away from the plasma processing chamber 10 by being configured to measure via an optical fiber.

[0024] The electron density measurement unit 60 measures the electron density inside the plasma processing chamber 10. The plasma processing apparatus 1 includes a VI probe as the electron density measurement unit 60, which measures the current and voltage values ​​of the power supplied from the power supply system 30 to the plasma processing chamber 10. The current and voltage values ​​of the power supplied from the power supply system 30 to the plasma processing chamber 10 correlate with the electron density of the plasma inside the plasma processing chamber 10. Therefore, by using the VI probe, the electron density measurement unit 60 can estimate the electron density of the plasma based on the measurement results from the electron density measurement unit 60. The control unit 2 is configured to acquire the measurement results from the electron density measurement unit 60, for example, via EtherCAT (registered trademark).

[0025] Furthermore, the electron density measurement unit 60 is not limited to measuring the electron density itself inside the plasma processing chamber 10; for example, it may also measure an electron density correlation parameter that correlates with the electron density. Also, the measurement of electron density in the electron density measurement unit 60 is not limited to measurement using a VI probe. In the electron density measurement unit 60, the measurement of electron density inside the plasma processing chamber 10 may also be performed using, for example, a measuring instrument capable of measuring plasma density. In the electron density measurement unit 60, the measurement of electron density inside the plasma processing chamber 10 may also be performed using, for example, an emission spectrometer, a microwave interferometer, or a plasma absorption probe.

[0026] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform the various processes described herein. The control unit 2 may be configured to control the elements of the plasma processing apparatus 1 to perform the various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 is implemented, for example, by a computer 2a. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The functions realized by the processing unit 2a1 described herein may be implemented in a circuit or processing circuit, including a general-purpose processor, an application-specific processor, integrated circuits, ASICs (Application Specific Integrated Circuits), a CPU (Central Processing Unit), a conventional circuit, and / or a combination thereof, programmed to realize the described functions. The processor is considered to be a circuit or processing circuit, including transistors and other circuits. The processor may be a programmed processor that executes a program stored in the storage unit 2a2. This program may be pre-stored in the storage unit 2a2 or retrieved via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 and executed by the processing unit 2a1. The medium may be various storage media readable by the computer 2a, or it may be a communication line connected to the communication interface 2a3. The storage unit 2a2 may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing device 1 via a communication line such as a LAN (Local Area Network).In this disclosure, circuits, units, and means are hardware programmed to perform or configured to perform the functions described. Such hardware may be any hardware described in this disclosure, or any hardware known to be programmed to perform or execute the functions described. If such hardware is a processor that is considered to be a type of circuit, such circuit, means, or unit is a combination of hardware and software used to constitute such hardware and / or processor.

[0027] <Plasma Processing System According to This Embodiment> The plasma processing system according to this embodiment will now be described. The plasma processing system according to this embodiment comprises a chamber, a substrate support unit disposed within the chamber, and a gas supply unit configured to supply processing gas into the chamber. The plasma processing system according to this embodiment also comprises a plasma generation unit configured to generate plasma from the processing gas within the chamber and perform plasma processing on a substrate on the substrate support unit. The plasma processing system according to this embodiment also comprises an emission intensity measurement unit configured to measure the emission intensity of a specific wavelength component contained in the plasma generated within the chamber during plasma processing. The plasma processing system according to this embodiment also comprises an electron density measurement unit configured to measure the electron density of the plasma generated within the chamber during plasma processing. Furthermore, the plasma processing system according to this embodiment includes an endpoint detection unit configured to detect the endpoint of the plasma processing based on the temporal change in the correlation between emission intensity and electron density measured at the same time. In another view, the plasma processing system according to this embodiment comprises a plasma processing chamber that houses a substrate, and an emission intensity measurement unit located inside the plasma processing chamber that measures the emission intensity of wavelengths caused by by-products or processing gas in the plasma processing. Furthermore, the plasma processing system according to this embodiment includes an electron density measuring unit that measures the electron density inside the plasma processing chamber, and a control unit that determines the endpoint of the plasma processing based on the difference between the temporal change in light emission intensity and the temporal change in electron density.

[0028] The plasma processing system monitors the emission of by-products and etchant gas from the target film to detect the switching of the processing film on the substrate. Based on the monitored emission state, the plasma processing system detects the film switching. The plasma processing system stops the process at the timing of the detected film switching. As described above, detecting the end of the process is called endpoint detection (EPD).

[0029] Plasma emission within a plasma processing chamber is affected not only by by-products generated from the target film and etchant gas, but also by changes in electron density due to state fluctuations within the plasma processing chamber. These electron density fluctuations become noise during endpoint detection.

[0030] To reduce the effects of electron density, for example, smoothing over a long period of time can be considered. However, smoothing may cause delays in processing. Delays in processing may affect the Critical Dimension (CD), reduce throughput, or damage the underlying film.

[0031] A specific example of the plasma processing system according to this embodiment will be described. Furthermore, by describing the plasma processing system according to this embodiment, the method for determining the endpoint of plasma processing in the plasma processing system according to this embodiment will be explained. Figure 2 is a diagram illustrating the relationship between emission intensity and electron density during plasma processing in plasma processing system S, which is an example of the plasma processing system according to this embodiment. In Figure 2, the horizontal axis conceptually represents time, and the vertical axis conceptually represents emission intensity and electron density, respectively. In Figure 2, point P1 represents emission intensity, and point P2 represents electron density. Emission intensity is, for example, the emission intensity at a wavelength in the emission spectrum caused by carbon nitride, which is an example of the processing gas. Emission intensity may also be the emission intensity at a wavelength caused by by-products. Note that at point P1, the point where the density of the processing gas changes significantly at the endpoint of plasma processing is indicated by a black circle.

[0032] As shown in Figure 2, in the plasma processing system S, as indicated by the lines A1 and A2 with arrows, when the electron density decreases, the light emission intensity also decreases accordingly.

[0033] The emission intensity is proportional to both the gas density and the electron density. The electron density is easily affected by the conditions of the plasma processing chamber. The emission intensity changes with increases and decreases in both the gas density and the electron density. In recent plasma processing, the reaction of the gas to be detected has become smaller due to factors such as a decrease in the aperture ratio of the object being etched. Therefore, if the electron density changes in the plasma processing chamber, the gas changes due to the reaction may be masked by the fluctuations in electron density and may not be detectable.

[0034] Therefore, the inventors discovered that since the luminescence intensity is proportional to both the gas density and the electron density, they could emphasize the change in luminescence intensity due to changes in gas density by calculating the difference in the temporal changes between the luminescence intensity and electron density, which were measured simultaneously.

[0035] Figure 3 illustrates the emission intensity during plasma processing corrected for fluctuations due to electron density in a plasma processing system S, which is an example of a plasma processing system according to this embodiment. Conceptually, the horizontal axis of Figure 3 represents time, and the vertical axis represents the emission intensity corrected for changes in electron density. In Figure 3, point P3 represents the emission intensity corrected for the temporal change in electron density. At point P3, the black circle indicates the point at the end of the plasma processing where the density of by-products or processing gas changes significantly.

[0036] As shown in Figure 2, the emission intensity changes with changes in electron density. Changes in emission intensity due to by-products or changes in the processing gas during plasma processing change independently of changes in electron density. Therefore, if the electron density changes similarly to the overall emission intensity over a predetermined time, the component of emission intensity that correlates with electron density is considered to be the component that changed due to electron density. In other words, if there is a correlation between the temporal changes of emission intensity and electron density over a predetermined time, the component of emission intensity that correlates with electron density is considered to be the component that changed due to electron density.

[0037] On the other hand, the emission intensity caused by by-products or processing gases in plasma processing is thought to change with a low correlation to the temporal change in electron density. Therefore, by extracting components with a low correlation to electron density and temporal change from the emission intensity measured by the emission intensity measurement unit 50, the emission intensity caused by by-products or processing gases in plasma processing can be extracted. In other words, by removing the portion of the emission intensity measured by the emission intensity measurement unit 50 that fluctuates due to electron density, the emission intensity can be corrected to reflect the emission intensity caused by by-products or processing gases in plasma processing. By extracting the emission intensity caused by by-products or processing gases in plasma processing, the accuracy of endpoint determination in plasma processing can be improved.

[0038] By removing the portion of the emission intensity that fluctuates due to electron density and extracting the emission intensity caused by by-products or the processing gas in the plasma treatment, it is possible to clearly identify portions where the density of by-products or the processing gas changes significantly, for example, as shown by the black circle at point P3 in Figure 3.

[0039] The specific processing of the control unit 2 will now be explained. The control unit 2 acquires the emission intensity and electron density of the plasma processing, which are measured simultaneously from the emission intensity measurement unit 50 and the electron density measurement unit 60, respectively. Then, the control unit 2 calculates the difference between the temporal change in emission intensity and the temporal change in electron density over a predetermined period. In the control unit 2, the difference between the temporal change in emission intensity and the temporal change in electron density is obtained, for example, by calculating the cross-correlation coefficient, the standard deviation in regression analysis, or the slope over a predetermined period, as will be described later. Note that the method for calculating the difference between the temporal change in emission intensity and the temporal change in electron density is not limited to the example described above. When the calculated difference between the temporal change in emission intensity and the temporal change in electron density is compared over time, a large difference is observed when the gas density changes at the endpoint of the plasma processing. For example, by graphing the difference between the confirmed temporal change in emission intensity and the temporal change in electron density over time, the endpoint of the plasma processing can be detected more clearly. The control unit 2 is an example of an endpoint detection unit.

[0040] The specific processing results are explained below.

[0041] <First Example of Processing in a Plasma Processing System> A first example of processing in a plasma processing system S, which is an example of a plasma processing system according to this embodiment, will be described. In the first example, the control unit 2 calculates the difference between the temporal change in light emission intensity and the temporal change in electron density using the cross-correlation coefficient. The control unit 2 calculates the cross-correlation coefficient between light emission intensity and electron density over a predetermined time, for example, a time set in the range of 0.5 seconds to 2 seconds. The control unit 2 calculates the cross-correlation coefficient while shifting the calculation period from the start of plasma processing.

[0042] Figure 4 illustrates a first example of processing in a plasma processing system S, which is an example of a plasma processing system according to this embodiment. The horizontal axis of Figure 4 represents the time since the start of plasma processing, and the vertical axis represents the correlation coefficient of cross-correlation. Line L1 shows the calculation result of the correlation coefficient of the cross-correlation between emission intensity and electron density. For example, by performing threshold processing on the result of the cross-correlation coefficient calculated using the threshold TH1, it is possible to detect a large change in correlation, as shown at time T1. When the emission intensity changes due to electron density, the correlation coefficient becomes high. On the other hand, when the emission intensity changes due to by-products or processing gas, the correlation coefficient becomes low. The control unit 2 determines that time T1 is the endpoint. The control unit 2 determines that time T1 is the endpoint in plasma processing by calculating the result of the cross-correlation coefficient along time and creating a correlation waveform.

[0043] The plasma processing system S can detect the endpoint in plasma processing by calculating the difference between the temporal change in light emission intensity and the temporal change in electron density using the cross-correlation coefficient.

[0044] <Second Example of Processing in Plasma Processing System>A second example of processing in a plasma processing system S, which is an example of the plasma processing system according to this embodiment, will be described. In the second example, the control unit 2 calculates the difference between the temporal change in the emission intensity and the temporal change in the electron density using the standard deviation in regression analysis. The control unit 2 calculates the standard deviation when performing regression analysis based on the emission intensity and the electron density at a predetermined time, for example, within the range of 0.5 seconds to 2 seconds. More specifically, the control unit 2 calculates the standard deviation when performing regression analysis with the emission intensity as the dependent variable and the electron density as the independent variable at a predetermined time. The control unit 2 calculates the standard deviation while shifting the period for calculation from the start of plasma processing.

[0045] FIG. 5 is a diagram for explaining a second example of processing in a plasma processing system S, which is an example of the plasma processing system according to this embodiment. The horizontal axis in FIG. 5 represents the time since the start of plasma processing, and the vertical axis represents the standard error indicating the standard deviation. The line L2 shows the calculation result of the standard deviation when performing regression analysis with the emission intensity as the dependent variable and the electron density as the independent variable. When the emission intensity changes due to the electron density, the standard deviation becomes small. On the other hand, when the emission intensity changes due to by-products or processing gases, the standard deviation becomes large. For example, the control unit 2 calculates the time T2 at which the standard deviation peaks. The control unit 2 determines that the time T2 is the end point. The control unit 2 calculates the result of the standard deviation when performing regression analysis with the emission intensity as the dependent variable and the electron density as the independent variable over time to create a standard error waveform, thereby determining the end point in plasma processing.

[0046] The plasma processing system S can detect the end point in plasma processing by calculating the difference between the temporal change in the emission intensity and the temporal change in the electron density using the standard deviation when performing regression analysis based on the emission intensity and the electron density.

[0047] <Third Example of Processing in Plasma Processing System>A third example of processing in a plasma processing system S, which is an example of the plasma processing system according to this embodiment, will be described. In the third example, the control unit 2 calculates the difference between the temporal change in the emission intensity and the temporal change in the electron density using the slope in the regression analysis. The control unit 2 calculates the slope when performing regression analysis based on the emission intensity and the electron density at a predetermined time, for example, a time determined within the range of 0.5 seconds to 2 seconds. More specifically, the control unit 2 calculates the slope when performing regression analysis with the emission intensity as the dependent variable and the electron density as the independent variable at a predetermined time. The control unit 2 calculates the slope while shifting the period to be calculated from the start of plasma processing.

[0048] FIG. 6 is a diagram for explaining a third example of processing in a plasma processing system S, which is an example of the plasma processing system according to this embodiment. The horizontal axis in FIG. 6 represents the time since the start of plasma processing, and the vertical axis represents the slope. The line L3 shows the calculation result of the slope when performing regression analysis with the emission intensity as the dependent variable and the electron density as the independent variable. When the emission changes due to by-products or processing gas, the slope changes significantly from the case where it changes due to the electron density. For example, by performing threshold processing on the calculated slope result using the threshold value TH3, as shown at time T3, it can be detected that the slope changes greatly. The control unit 2 determines that time T3 is the end point. The control unit 2 calculates the result of the slope when performing regression analysis with the emission intensity as the dependent variable and the electron density as the independent variable along with time, and creates a slope waveform to determine the end point in plasma processing.

[0049] The plasma processing system S can detect the end point in plasma processing by calculating the difference between the temporal change in the emission intensity and the temporal change in the electron density using the slope when performing regression analysis based on the emission intensity and the electron density.

[0050] In the second and third examples, the dependent variable and the independent variable in the regression analysis may be reversed. Also, the first, second, and third examples may be combined for determination, or determination may be made considering other detection results or prior information.

[0051] According to the plasma processing system of this embodiment, the influence of electron density on the light emission intensity inside the plasma processing chamber can be suppressed. By suppressing the influence of electron density on the light emission intensity inside the plasma processing chamber, the accuracy of endpoint determination in process processing can be improved.

[0052] The plasma processing system according to the present embodiment disclosed herein should be considered in all respects as illustrative and not restrictive. The above embodiments can be modified and improved in various ways without departing from the scope and spirit of the appended claims. The matters described in the above embodiments can be otherwise configured and combined in a non-consistent manner.

[0053] The embodiments disclosed above include, for example, the following aspects:

[0054] [Note 1] A plasma processing system comprising: a chamber; a substrate support portion disposed within the chamber; a gas supply portion configured to supply a processing gas into the chamber; a plasma generation portion configured to generate plasma from the processing gas within the chamber and perform plasma processing on a substrate on the substrate support portion; an emission intensity measuring portion configured to measure the emission intensity of a specific wavelength component contained in the plasma generated within the chamber during the plasma processing; an electron density measuring portion configured to measure the electron density of the plasma generated within the chamber during the plasma processing; and an endpoint detection portion configured to detect the endpoint of the plasma processing based on the temporal change in the correlation between the emission intensity and the electron density measured at the same time.

[0055] [Note 2] The plasma processing system according to Note 1, wherein the endpoint detection unit is configured to detect the endpoint based on the temporal change in the cross-correlation coefficient between the light emission intensity and the electron density.

[0056] [Note 3] The plasma processing system according to Note 1, wherein the endpoint detection unit is configured to detect the endpoint based on the temporal change in the standard deviation when regression analysis is performed based on the light emission intensity and the electron density.

[0057] [Note 4] The plasma processing system according to Note 1, wherein the endpoint detection unit is configured to detect the endpoint based on the temporal change in the slope when regression analysis is performed based on the light emission intensity and the electron density.

[0058] [Note 5] The plasma processing system according to any one of Notes 1 to 4, wherein the light emission intensity measuring unit is configured to measure the light emission intensity via an optical fiber.

[0059] [Note 6] The plasma processing system according to any one of Notes 1 to 5, wherein the endpoint detection unit is configured to acquire the measurement results from the light emission intensity measurement unit via Ethernet.

[0060] [Note 7] The plasma processing system according to any one of Notes 1 to 6, wherein the endpoint detection unit is configured to acquire the measurement results from the electron density measurement unit via EtherCAT.

[0061] [Note 8] A device for detecting the endpoint of plasma processing in a plasma processing apparatus, comprising: an emission intensity measuring unit configured to measure the emission intensity of a specific wavelength component contained in the plasma generated during the plasma processing; an electron density measuring unit configured to measure the electron density of the plasma generated during the plasma processing; and an endpoint detection unit configured to detect the endpoint of the plasma processing based on the temporal change in the correlation between the emission intensity and the electron density measured at the same time.

[0062] [Note 9] The apparatus according to Note 8, wherein the endpoint detection unit is configured to detect the endpoint based on the temporal change in the cross-correlation coefficient between the light emission intensity and the electron density.

[0063] [Note 10] The apparatus as described in Note 8, wherein the endpoint detection unit is configured to detect the endpoint based on the temporal change in the standard deviation when regression analysis is performed based on the luminescence intensity and the electron density.

[0064] [Note 11] The apparatus according to Note 8, wherein the endpoint detection unit is configured to detect the endpoint based on the temporal change in the slope when regression analysis is performed based on the luminescence intensity and the electron density.

[0065] [Note 12] The apparatus according to any one of Notes 8 to 11, wherein the light emission intensity measuring unit is configured to measure the light emission intensity via an optical fiber.

[0066] [Note 13] The apparatus according to any one of Notes 8 to 12, wherein the endpoint detection unit is configured to acquire the measurement results from the light emission intensity measurement unit via Ethernet.

[0067] [Note 14] The apparatus according to any one of Notes 8 to 13, wherein the endpoint detection unit is configured to acquire the measurement result from the electron density measurement unit via EtherCAT.

[0068] [Note 15] A method for detecting the endpoint of plasma processing in a plasma processing apparatus, comprising: (a) measuring the emission intensity of a specific wavelength component contained in the plasma generated during the plasma processing; (b) measuring the electron density of the plasma at the same timing as step (a); (c) repeating step (a) and step (b); and (d) detecting the endpoint of the plasma processing based on the temporal change in the correlation between the emission intensity and the electron density measured at the same timing.

[0069] [Note 16] The method according to Note 15, wherein step (d) is a step of detecting the endpoint based on the temporal change in the cross-correlation coefficient between the luminescence intensity and the electron density.

[0070] [Note 17] The method according to Note 15, wherein step (d) is a step of detecting the endpoint based on the temporal change in the standard deviation when regression analysis is performed based on the luminescence intensity and the electron density.

[0071] [Note 18] The method according to Note 15, wherein step (d) is a step of detecting the endpoint based on the temporal change of the slope when regression analysis is performed based on the luminescence intensity and the electron density.

[0072] Furthermore, the disclosed embodiments include, for example, the following other embodiments:

[0073] [Note 1] A plasma processing system comprising: a plasma processing chamber that houses a substrate; an emission intensity measuring unit that measures the emission intensity of wavelengths caused by by-products or processing gases in the plasma processing inside the plasma processing chamber; an electron density measuring unit that measures the electron density inside the plasma processing chamber; and a control unit that determines the endpoint of the plasma processing based on the difference between the temporal change in emission intensity and the temporal change in electron density.

[0074] [Note 2] The plasma processing system according to Note 1, wherein the control unit calculates the cross-correlation coefficient between the light emission intensity and the electron density, and determines the endpoint based on the calculated cross-correlation coefficient.

[0075] [Note 3] The plasma processing system according to Note 1, wherein the control unit calculates the standard deviation when regression analysis is performed based on the light emission intensity and the electron density, and determines the endpoint based on the standard deviation.

[0076] [Note 4] The plasma processing system according to Note 1, wherein the control unit calculates the slope when regression analysis is performed based on the light emission intensity and the electron density, and determines the endpoint based on the slope.

[0077] [Note 5] A method for determining the endpoint of a plasma processing system, comprising: a plasma processing chamber that houses a substrate; an emission intensity measuring unit that measures the emission intensity of wavelengths caused by by-products or processing gases in the plasma processing inside the plasma processing chamber; and an electron density measuring unit that measures the electron density inside the plasma processing chamber, wherein the endpoint of the plasma processing is determined based on the difference between the temporal change in emission intensity and the temporal change in electron density.

[0078] This application claims priority to Basic Patent Application No. 2025-013234, filed with the Japan Patent Office on January 29, 2025, the entire contents of which are incorporated herein by reference.

[0079] S Plasma processing system 1 Plasma processing device 2 Control unit 10 Plasma processing chamber 50 Luminous emission intensity measurement unit 60 Electron density measurement unit W Substrate

Claims

1. A plasma processing system comprising: a chamber; a substrate support portion disposed within the chamber; a gas supply portion configured to supply a processing gas into the chamber; a plasma generation portion configured to generate plasma from the processing gas within the chamber and perform plasma processing on a substrate on the substrate support portion; an emission intensity measuring portion configured to measure the emission intensity of a specific wavelength component contained in the plasma generated within the chamber during the plasma processing; an electron density measuring portion configured to measure the electron density of the plasma generated within the chamber during the plasma processing; and an endpoint detection portion configured to detect the endpoint of the plasma processing based on the temporal change in the correlation between the emission intensity and the electron density measured at the same time.

2. The plasma processing system according to claim 1, wherein the endpoint detection unit is configured to detect the endpoint based on the temporal change in the cross-correlation coefficient between the light emission intensity and the electron density.

3. The plasma processing system according to claim 1, wherein the endpoint detection unit is configured to detect the endpoint based on the temporal change in the standard deviation when regression analysis is performed based on the light emission intensity and the electron density.

4. The plasma processing system according to claim 1, wherein the endpoint detection unit is configured to detect the endpoint based on the temporal change in the slope when regression analysis is performed based on the emission intensity and the electron density.

5. The plasma processing system according to any one of claims 1 to 4, wherein the light emission intensity measuring unit is configured to measure the light emission intensity via an optical fiber.

6. The plasma processing system according to claim 5, wherein the endpoint detection unit is configured to acquire the measurement results from the light emission intensity measurement unit via Ethernet.

7. The plasma processing system according to claim 6, wherein the endpoint detection unit is configured to acquire the measurement results from the electron density measurement unit via EtherCAT.

8. A device for detecting the endpoint of plasma processing in a plasma processing apparatus, comprising: an emission intensity measuring unit configured to measure the emission intensity of a specific wavelength component contained in the plasma generated during the plasma processing; an electron density measuring unit configured to measure the electron density of the plasma generated during the plasma processing; and an endpoint detection unit configured to detect the endpoint of the plasma processing based on the temporal change in the correlation between the emission intensity and the electron density measured at the same time.

9. The apparatus according to claim 8, wherein the endpoint detection unit is configured to detect the endpoint based on the temporal change in the cross-correlation coefficient between the light emission intensity and the electron density.

10. The apparatus according to claim 8, wherein the endpoint detection unit is configured to detect the endpoint based on the temporal change in the standard deviation when regression analysis is performed based on the luminescence intensity and the electron density.

11. The apparatus according to claim 8, wherein the endpoint detection unit is configured to detect the endpoint based on the temporal change in the slope when regression analysis is performed based on the luminescence intensity and the electron density.

12. The apparatus according to any one of claims 8 to 11, wherein the light emission intensity measuring unit is configured to measure the light emission intensity via an optical fiber.

13. The apparatus according to claim 12, wherein the endpoint detection unit is configured to acquire the measurement result from the light emission intensity measurement unit via Ethernet.

14. The apparatus according to claim 13, wherein the endpoint detection unit is configured to acquire the measurement result from the electron density measurement unit via EtherCAT.

15. A method for detecting the endpoint of plasma processing in a plasma processing apparatus, comprising: (a) measuring the emission intensity of a specific wavelength component contained in the plasma generated during the plasma processing; (b) measuring the electron density of the plasma at the same timing as step (a); (c) repeating step (a) and step (b); and (d) detecting the endpoint of the plasma processing based on the temporal change in the correlation between the emission intensity and the electron density measured at the same timing.

16. The method according to claim 15, wherein step (d) comprises a step of detecting the endpoint based on the temporal change in the cross-correlation coefficient between the luminescence intensity and the electron density.

17. The method according to claim 15, wherein step (d) comprises a step of detecting the endpoint based on the temporal change in the standard deviation when regression analysis is performed based on the luminescence intensity and the electron density.

18. The method according to claim 15, wherein step (d) comprises a step of detecting the endpoint based on the temporal change of the slope when regression analysis is performed based on the luminescence intensity and the electron density.

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