Plasma processing apparatus, plasma state detection method, and program

Abstract

The present application provides a kind of plasma processing device, plasma state detection method and program.Measurement part controls the supply power supplied to heater by heater control part to make the temperature of heater fixed, measures the supply power in unignited state of plasma without ignition and ignited state after plasma ignition.Parameter calculation part uses the supply power in unignited state and ignited state measured by measurement part to calculate the heat input amount from plasma as parameter.Output part outputs information based on the heat input amount calculated by parameter calculation part.

Description

[0001] This application is a divisional application of the application filed on June 17, 2019, with application number 201980013656.8 (PCT / JP2019 / 023793) and entitled "Plasma Processing Apparatus, Plasma State Detection Method and Plasma State Detection Program". Technical Field

[0002] This disclosure relates to a plasma processing apparatus, a plasma state detection method, and a plasma state detection program. Background Technology

[0003] Previously, plasma processing apparatuses were known to use plasma to perform plasma processing such as etching on processed objects like semiconductor wafers (hereinafter also referred to as "wafers"). Furthermore, a technique was proposed to detect the state of the plasma by arranging various detectors and electrical sensors within the processing container of this plasma processing apparatus.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2009-194032

[0007] Patent Document 2: Japanese Patent Application Publication No. 2009-087790

[0008] Patent Document 2: Japanese Patent Publication No. 2014-513390 Summary of the Invention

[0009] The problem the invention aims to solve

[0010] This disclosure provides a technique for detecting the state of plasma without configuring sensors.

[0011] Solution for solving the problem

[0012] One aspect of the plasma processing apparatus disclosed herein includes a stage, a heater control unit, a measuring unit, a parameter calculation unit, and an output unit. The stage is equipped with a heater capable of adjusting the temperature of the surface on which the object to be processed, the plasma object, is placed. The heater control unit controls the power supplied to the heater to bring it to a set temperature. The heater control unit controls the power supplied to the heater to maintain a constant heater temperature. The measuring unit measures the power supplied during the unignited state (when the plasma is not ignited) and the power supplied during the transition state (when the power supplied to the heater decreases from the point of plasma ignition). The parameter calculation unit uses the power supplied during the unignited state and the transition state measured by the measuring unit to fit a calculation model to calculate the heat input from the plasma. This calculation model includes the heat input as a parameter to calculate the power supplied during the transition state. The output unit outputs information based on the heat input calculated by the parameter calculation unit.

[0013] The effects of the invention

[0014] According to this disclosure, the state of plasma can be detected without configuring sensors inside the processing container. Attached Figure Description

[0015] Figure 1 This is a cross-sectional view showing an example of the general structure of the plasma processing apparatus according to the embodiment.

[0016] Figure 2 This is a top view showing an example of the structure of the platform involved in the embodiment.

[0017] Figure 3 This is a block diagram illustrating an example of the outline structure of the control unit of the plasma processing apparatus according to the embodiment.

[0018] Figure 4 This is a diagram illustrating an example of the flow of energy that affects the temperature of a wafer.

[0019] Figure 5A This is a diagram that schematically illustrates an example of the flow of energy in an unignited state.

[0020] Figure 5B This is a diagram that schematically illustrates an example of the flow of energy during ignition.

[0021] Figure 6 This is a diagram illustrating an example of the changes in temperature of wafer W and the power supplied to heater HT.

[0022] Figure 7 This is a diagram that schematically illustrates an example of the flow of energy during ignition.

[0023] Figure 8 This is a diagram that provides a summary representation of the temperature changes in the unignited and transition states due to the plasma density distribution.

[0024] Figure 9 This is a diagram that schematically illustrates an example of energy flow in the unignited and transitional states.

[0025] Figure 10 This is a diagram illustrating an example of the changes in temperature of wafer W and the power supplied to heater HT.

[0026] Figure 11A This is a diagram showing an example of the output representing information about the density distribution of the plasma.

[0027] Figure 11B This is a diagram showing an example of the output representing information about the density distribution of the plasma.

[0028] Figure 12 This is a schematic diagram illustrating plasma etching.

[0029] Figure 13 This is a flowchart illustrating an example of the plasma state detection and plasma state control process involved in the implementation method.

[0030] Figure 14 This is a top view showing an example of the division of the mounting surface of the platform according to the embodiment. Detailed Implementation

[0031] The embodiments of the plasma processing apparatus, plasma state detection method, and plasma state detection procedure disclosed in this application will now be described in detail with reference to the accompanying drawings. However, these embodiments are not intended to limit the disclosed plasma processing apparatus, plasma state detection method, and plasma state detection procedure.

[0032] Furthermore, in some plasma processing apparatuses, various detectors and electrical sensors are installed within the processing container to detect the plasma state. However, sometimes when sensors are placed within the processing container and near the plasma generation region, the plasma state changes due to the influence of the sensors. This can affect the characteristics and uniformity of the plasma treatment of the membrane being processed. Additionally, particles may be generated or abnormal discharges may occur within the plasma processing apparatus. Moreover, when sensors are installed within the processing container, plasma treatment of the membrane may sometimes be impossible. Consequently, the plasma state during the actual plasma treatment process cannot be detected within the plasma processing apparatus. Therefore, it is desirable to detect the plasma state without installing sensors within the processing container.

[0033] [Structure of the plasma processing device]

[0034] First, the structure of the plasma processing apparatus 10 according to the embodiment will be described. Figure 1 This is a cross-sectional view showing an example of the general structure of the plasma processing apparatus according to the embodiment. Figure 1 The plasma processing apparatus 10 shown is a capacitively coupled parallel-plate plasma etching apparatus. The plasma processing apparatus 10 includes a generally cylindrical processing container 12. The processing container 12 is made of, for example, aluminum. Furthermore, the surface of the processing container 12 is anodized.

[0035] A mounting stage 16 is provided within the processing container 12. The mounting stage 16 includes an electrostatic chuck 18 and a base 20. The upper surface of the electrostatic chuck 18 is configured as a mounting surface for placing the object to be processed as plasma treatment. In this embodiment, a wafer W is placed on the upper surface of the electrostatic chuck 18 as the object to be processed. The base 20 has a generally disk-shaped form, and its main portion is made of a conductive metal, such as aluminum. The base 20 constitutes the lower electrode. The base 20 is supported by a support portion 14. The support portion 14 is a cylindrical member extending from the bottom of the processing container 12.

[0036] Base station 20 is electrically connected to a first high-frequency power supply HFS. The first high-frequency power supply HFS is a power source that generates high-frequency power for plasma generation, producing frequencies from 27 MHz to 100 MHz; in one example, it generates 40 MHz high-frequency power. This generates plasma directly above base station 20. Matching unit MU1 has circuitry for matching the output impedance of the first high-frequency power supply HFS with the input impedance of the load side (base station 20 side).

[0037] Additionally, the base station 20 is electrically connected to a second high-frequency power supply LFS via a matching converter MU2. The second high-frequency power supply LFS generates high-frequency power (high-frequency bias power) for attracting ions to the wafer W and supplies this high-frequency bias power to the base station 20. This generates a bias potential in the base station 20. The frequency of the high-frequency bias power is in the range of 400 kHz to 13.56 MHz, and in one example, it is 3 MHz. The matching converter MU2 has circuitry for matching the output impedance of the second high-frequency power supply LFS with the input impedance on the load side (base station 20 side).

[0038] An electrostatic chuck 18 is provided on the base 20. The electrostatic chuck 18 uses electrostatic forces such as Coulomb force to attract and hold the wafer W. The electrostatic chuck 18 has an electrode E1 for electrostatic attraction within its ceramic body. The electrode E1 is electrically connected to a DC power supply 22 via a switch SW1. The attraction force holding the wafer W depends on the value of the DC voltage applied from the DC power supply 22.

[0039] A focusing ring FR is disposed on the upper surface of the base 20 and around the electrostatic chuck 18. The focusing ring FR is provided to improve the uniformity of plasma processing. The focusing ring FR is made of a material appropriately selected according to the plasma processing to be performed, such as silicon or quartz.

[0040] A refrigerant flow path 24 is formed inside the base 20. Refrigerant is supplied to the refrigerant flow path 24 from a cooling device located outside the processing container 12 via pipe 26a. The refrigerant supplied to the refrigerant flow path 24 returns to the cooling device via pipe 26b. Furthermore, details of the mounting stage 16, including the base 20 and the electrostatic chuck 18, will be described later.

[0041] An upper electrode 30 is provided inside the processing container 12. The upper electrode 30 is arranged above the stage 16 and facing the base 20, and the base 20 and the upper electrode 30 are arranged to be approximately parallel to each other.

[0042] The upper electrode 30 is supported on the upper part of the processing container 12 via an insulating shielding member 32. The upper electrode 30 may include an electrode plate 34 and an electrode support 36. The electrode plate 34 faces the processing space S and is provided with a plurality of gas ejection holes 34a. The electrode plate 34 may be made of a conductor or semiconductor with low Joule heating and low resistance.

[0043] The electrode support 36 supports the electrode plate 34 in a detachable manner and can be made of a conductive material such as aluminum. The electrode support 36 can have a water-cooling structure. A gas diffusion chamber 36a is provided inside the electrode support 36. Multiple gas flow holes 36b extend downward from the gas diffusion chamber 36a and communicate with the gas ejection hole 34a. Additionally, a gas inlet 36c is formed in the electrode support 36 for guiding processed gas into the gas diffusion chamber 36a, and the gas inlet 36c is connected to a gas supply pipe 38.

[0044] The gas supply pipe 38 is connected to the gas source assembly 40 via a valve assembly 42 and a flow controller assembly 44. The valve assembly 42 has multiple on / off valves, and the flow controller assembly 44 has multiple flow controllers such as flow mass controllers. Additionally, the gas source assembly 40 has gas sources for various gases required for plasma processing. The multiple gas sources of the gas source assembly 40 are connected to the gas supply pipe 38 via corresponding on / off valves and corresponding mass flow controllers.

[0045] In the plasma processing apparatus 10, one or more gas sources selected from a plurality of gas sources in the gas source group 40 are supplied to the gas supply pipe 38. The gas supplied to the gas supply pipe 38 reaches the gas diffusion chamber 36a and is ejected into the processing space S through the gas flow hole 36b and the gas ejection hole 34a.

[0046] In addition, such as Figure 1 As shown, the plasma processing apparatus 10 may also include a grounding conductor 12a. The grounding conductor 12a is a generally cylindrical grounding conductor, which is arranged to extend from the side wall of the processing container 12 to a position higher than the height of the upper electrode 30.

[0047] In addition, in the plasma processing apparatus 10, a deposit shielding member 46 is detachably provided along the inner wall of the processing container 12. Furthermore, a deposit shielding member 46 is also provided on the outer periphery of the support portion 14. The deposit shielding member 46 is used to prevent etching byproducts (deposits) from adhering to the processing container 12, and is constructed by coating the aluminum material with a ceramic such as Y2O3.

[0048] On the bottom side of the processing container 12, an exhaust plate 48 is provided between the support portion 14 and the inner wall of the processing container 12. The exhaust plate 48 can be constructed, for example, by coating aluminum with a ceramic such as Y2O3. Below the exhaust plate 48, an exhaust port 12e is provided on the processing container 12. The exhaust port 12e is connected to an exhaust device 50 via an exhaust pipe 52. The exhaust device 50 has a vacuum pump such as a turbomolecular pump, which can reduce the pressure inside the processing container 12 to the desired vacuum level. In addition, a wafer W loading / unloading outlet 12g is provided on the side wall of the processing container 12, and the loading / unloading outlet 12g can be opened and closed by a gate valve 54.

[0049] The plasma processing apparatus 10, configured as described above, is uniformly controlled by a control unit 100. The control unit 100, for example, is a computer, which controls all parts of the plasma processing apparatus 10. The plasma processing apparatus 10 is uniformly controlled by the control unit 100.

[0050] [Structure of the mounting platform]

[0051] Next, the stage 16 will be described in detail. Figure 2This is a top view showing an example of the structure of the mounting stage according to the embodiment. As described above, the mounting stage 16 has an electrostatic chuck 18 and a base 20. The electrostatic chuck 18 has a ceramic body portion 18m. The body portion 18m has a generally disc-shaped form. The body portion 18m provides a mounting region 18a and an outer peripheral region 18b. When viewed from above, the mounting region 18a is a generally circular region. A wafer W is mounted on the upper surface of the mounting region 18a. That is, the upper surface of the mounting region 18a functions as a mounting surface for mounting the wafer W. The diameter of the mounting region 18a can be approximately the same as the diameter of the wafer W or can be slightly smaller than the diameter of the wafer W. The outer peripheral region 18b is a region surrounding the mounting region 18a and extends in a generally annular shape. In this embodiment, the upper surface of the outer peripheral region 18b is at a lower position than the upper surface of the mounting region 18a.

[0052] like Figure 2 As shown, the electrostatic chuck 18 has an electrode E1 for electrostatic adsorption within the mounting area 18a. As described above, the electrode E1 is connected to the DC power supply 22 via the switch SW1.

[0053] Furthermore, multiple heaters HT are disposed within the mounting region 18a and below the electrode E1. In this embodiment, the mounting region 18a is divided into multiple segmented regions, and a heater HT is disposed in each segmented region. For example... Figure 2 As shown, multiple heaters HT are provided within a central circular region and several concentric annular regions surrounding the circular region 18a. Furthermore, within each of the annular regions, the multiple heaters HT are arranged circumferentially. Figure 2 The method of dividing the segmented region shown is an example and is not limited to this. The mounting region 18a can be divided into more segmented regions. For example, the mounting region 18a can be divided into segmented regions where the angular width decreases and the radial width decreases as it approaches the outer periphery. The heater HT is individually connected to the base 20 via wiring (not shown) disposed on the outer periphery of the base 20. Figure 1 The heater power supply HP is shown. Under the control of the control unit 100, the heater power supply HP supplies individually adjusted power to each heater HT. As a result, the heat emitted by each heater HT is individually controlled, and the temperature of the multiple segmented areas within the mounting area 18a is individually adjusted.

[0054] A power detection unit (PD) is provided in the heater power supply HP to detect the power supplied to each heater HT. Furthermore, the power detection unit (PD) can be separately installed from the heater power supply HP on the wiring for the flow of power from the heater power supply HP to each heater HT. The power detection unit (PD) detects the power supplied to each heater HT. For example, the power detection unit (PD) detects the electrical force [W] as the power supplied to each heater HT. The heater HT heats up based on the electrical force. Therefore, the electrical force supplied to the heater HT represents the heater power. The power detection unit (PD) notifies the control unit 100 of the power data indicating the detected power supplied to each heater HT.

[0055] In addition, the mounting platform 16 is equipped with temperature sensors (not shown) in each segmented area of ​​the mounting region 18a, capable of detecting the temperature of the heater HT. The temperature sensors can be separate temperature-measuring elements from the heater HT. Furthermore, the temperature sensors are disposed in the wiring for supplying power to the heater HT, and can primarily utilize the property that the resistance of a metal increases proportionally with temperature rise, detecting the temperature based on the resistance value obtained by measuring the voltage and current applied to the heater HT. The sensor values ​​detected by each temperature sensor are sent to the temperature measuring unit TD. The temperature measuring unit TD measures the temperature of each segmented area of ​​the mounting region 18a based on the sensor values. The temperature measuring unit TD then notifies the control unit 100 of the temperature data representing the temperature of each segmented area of ​​the mounting region 18a.

[0056] Furthermore, heat transfer gas, such as He gas, can be supplied between the upper surface of the electrostatic chuck 18 and the back surface of the wafer W via a heat transfer gas supply mechanism and gas supply line (not shown).

[0057] [Structure of the Control Department]

[0058] Next, the control unit 100 will be described in detail. Figure 3 This is a block diagram illustrating an example of the outline structure of the control unit of the plasma processing apparatus according to the embodiment. The control unit 100 is provided with an external interface 101, a process controller 102, a user interface 103, and a storage unit 104.

[0059] The external interface 101 can communicate with various parts of the plasma processing apparatus 10 to input and output various data. For example, power data indicating the supply power from the power detection unit PD to each heater HT can be input to the external interface 101. In addition, temperature data indicating the temperature of each segmented region of the mounting area 18a can be input to the external interface 101 from the temperature measuring unit TD. Furthermore, the external interface 101 outputs control data to the heater power supply HP for controlling the supply power to each heater HT.

[0060] The process controller 102 has a CPU (Central Processing Unit) to control the various parts of the plasma processing apparatus 10.

[0061] The user interface 103 consists of a keyboard for the process manager to input commands for managing the plasma processing device 10, a display that visually shows the operating status of the plasma processing device 10, and the like.

[0062] The storage unit 104 stores control programs (software) for implementing various processes executed by the plasma processing apparatus 10 under the control of the process controller 102, process data including processing conditions, and parameters related to the plasma processing apparatus and process. Furthermore, the control programs, processing condition data, and other process data can be used while stored on a computer-readable recording medium (e.g., hard disk, DVD, floppy disk, semiconductor memory, etc.). Additionally, the process data can be transferred online from other devices at any time via, for example, a dedicated line.

[0063] The process controller 102 has an internal memory for storing programs and data, reads the control program stored in the storage unit 104, and executes the read control program. The process controller 102 functions as various processing units by running the control program. For example, the process controller 102 has the functions of a heater control unit 102a, a measurement unit 102b, a parameter calculation unit 102c, an output unit 102d, an alarm unit 102e, a change unit 102f, and a set temperature calculation unit 102g. Furthermore, the functions of the heater control unit 102, measurement unit 102b, parameter calculation unit 102c, output unit 102d, alarm unit 102e, change unit 102f, and set temperature calculation unit 102g can be implemented distributed among multiple controllers.

[0064] Here, we will explain the flow of energy that affects the temperature of wafer W. Figure 4 This is a diagram schematically illustrating an example of the flow of energy that affects the temperature of a wafer. Figure 4 The image is simplified to represent a wafer W and a stage 16 including an electrostatic chuck (ESC) 18. Figure 4 The example illustrates the flow of energy affecting the temperature of the wafer W in a segmented region of the mounting area 18a of the electrostatic chuck 18. The mounting stage 16 has the electrostatic chuck 18 and the base 20. The electrostatic chuck 18 and the base 20 are bonded together by an adhesive layer 19. A heater HT is disposed inside the mounting area 18a of the electrostatic chuck 18. A refrigerant flow path 24 for the flow of refrigerant is formed inside the base 20.

[0065] The heater HT heats up and its temperature rises according to the power supplied from the heater power source HP. Figure 4 In this context, the power supplied to the heater HT is expressed as the heater power P. h In the heater HT, the heater power P is generated. h The heat output per unit area (heat flux) q is obtained by dividing the area A of the region where the heater HT is located by the electrostatic chuck 18. h .

[0066] Furthermore, during plasma processing, the temperature of wafer W rises due to the heat input from the plasma. Figure 4 In the figure, q represents the heat flux from the plasma per unit area, obtained by dividing the amount of heat input from the plasma to the wafer W by the area of ​​the wafer W. p .

[0067] It is known that the amount of ions in the plasma irradiated by the main heat input from the plasma is proportional to the product of the bias potential used to attract ions from the plasma to the wafer W. The amount of ions in the plasma irradiated by the plasma to the wafer W is proportional to the electron density of the plasma. The electron density of the plasma is proportional to the power of the high-frequency power HFS applied from the first high-frequency power source HFS to generate the plasma. In addition, the electron density of the plasma depends on the pressure inside the processing container 12. The bias potential used to attract ions from the plasma to the wafer W is proportional to the power of the high-frequency power LFS applied from the second high-frequency power source LFS to generate the bias potential. In addition, the bias potential used to attract ions from the plasma to the wafer W depends on the pressure inside the processing container 12. Furthermore, when no high-frequency power LFS is applied to the stage 12, ions are attracted to the stage by the potential difference between the plasma potential (plasma potential) generated during plasma generation and the stage 12.

[0068] In addition, the heat input from the plasma includes heating due to plasma emission, irradiation of the wafer W by electrons and free radicals in the plasma, and surface reactions on the wafer W caused by ions and free radicals. These components also depend on the power and pressure of the alternating current. Furthermore, the heat input from the plasma also depends on the device parameters related to plasma generation, such as the distance between the stage 16 and the upper electrode 30, and the type of gas supplied to the processing space S.

[0069] Heat transferred to wafer W is transferred to electrostatic chuck 18. However, not all heat from wafer W is transferred to electrostatic chuck 18; rather, the heat is transferred based on the difficulty of heat transfer, such as the degree of contact between wafer W and electrostatic chuck 18. The difficulty of heat transfer, i.e., thermal resistance, is inversely proportional to the cross-sectional area relative to the direction of heat transfer. Therefore, in… Figure 4 In this context, the difficulty of heat transfer from wafer W to the surface of electrostatic chuck 18 is expressed as the thermal resistance R per unit area between the surfaces of wafer W and electrostatic chuck 18. th • A. Furthermore, A represents the area of ​​the region where the heater HT is located. R th The overall thermal resistance of the area where the heater HT is installed. Additionally, in Figure 4 In this context, the amount of heat input from wafer W to the surface of electrostatic chuck 18 is expressed as the heat flux q per unit area from wafer W to the surface of electrostatic chuck 18. Furthermore, the thermal resistance R per unit area between the surfaces of wafer W and electrostatic chuck 18 is also expressed as... th A depends on the surface condition of the electrostatic chuck 18, the value of the DC voltage applied from the DC power supply 22 to hold the wafer W, and the pressure of the heat transfer gas supplied between the upper surface of the electrostatic chuck 18 and the back surface of the wafer W. Additionally, the thermal resistance R... th A also depends on the device parameters related to thermal resistance or thermal conductivity.

[0070] The heat transferred to the surface of the electrostatic chuck 18 causes the temperature of the electrostatic chuck 18 to rise, and this heat is further transferred to the heater HT. Figure 4 In this context, the amount of heat input from the surface of the electrostatic chuck 18 to the heater HT is expressed as the heat flux per unit area from the surface of the electrostatic chuck 18 to the heater HT, q. c .

[0071] On the other hand, the base 20 is cooled by the refrigerant flowing in the refrigerant flow path 24, and the contacting electrostatic chuck 18 is also cooled. Figure 4 In this context, the heat dissipation from the back of the electrostatic chuck 18 through the adhesive layer 19 to the base 20 is expressed as the heat flux q per unit area from the back of the electrostatic chuck 18 to the base 20. sus Therefore, the heater HT is cooled by heat dissipation, and its temperature drops.

[0072] When the temperature of heater HT is controlled at a constant value, the sum of the heat input transferred to heater HT and the heat generated through heater HT is equal to the heat dissipation from heater HT. For example, in the unignited state where the plasma is not ignited, the heat generated through heater HT is equal to the heat dissipation from heater HT. Figure 5A This is a diagram schematically illustrating an example of energy flow in an unignited state. Figure 5A In the example, heat of "100" is dissipated from the heater HT by cooling from the base 20. For example, when the temperature of the heater HT is controlled to be constant, the heater power supply HP is connected to the heater power P. h This causes the heater HT to generate "100" of heat.

[0073] On the other hand, for example, in the ignition state where the plasma has been ignited, the sum of the heat input to the heater HT and the heat generated by the heater HT is equal to the heat dissipation from the heater HT. Figure 5B This diagram schematically illustrates an example of energy flow during ignition. Here, the ignition state includes a transitional state and a stable state. The transitional state is, for example, a state where the heat input to wafer W and electrostatic chuck 18 is greater than the heat dissipation, and the temperature of wafer W and electrostatic chuck 18 tends to rise over time. The stable state is a state where the heat input to wafer W and electrostatic chuck 18 are equal to the heat dissipation, and the tendency for the temperature of wafer W and electrostatic chuck 18 to rise over time disappears, resulting in a roughly constant temperature.

[0074] exist Figure 5B In the example, heat "100" is dissipated from the heater HT by cooling from the base 20. In the ignition state, the wafer W's temperature rises due to heat input from the plasma until it reaches a stable state. Heat is transferred from the wafer W to the heater HT via the electrostatic chuck 18. As described above, when the temperature of the heater HT is controlled at a constant level, the heat input to the heater HT is equal to the heat dissipated from the heater HT. Regarding the heater HT, the heat required to maintain the temperature of the heater HT at a constant level decreases. Therefore, the power supplied to the heater HT decreases.

[0075] For example, in Figure 5B In the example set as a "transition state", 80% of the heat is transferred from the plasma to the wafer W. The heat transferred to the wafer W is then transferred to the electrostatic chuck 18. Furthermore, when the temperature of the wafer W is not in a stable state, a portion of the heat transferred to the wafer W contributes to the temperature rise of the wafer W. The amount of heat contributing to the temperature rise of the wafer W depends on the heat capacity of the wafer W. Therefore, 60% of the 80% of the heat transferred from the plasma to the wafer W is transferred from the wafer W to the surface of the electrostatic chuck 18. The heat transferred to the surface of the electrostatic chuck 18 is then transferred to the heater HT. Furthermore, when the temperature of the electrostatic chuck 18 is not in a stable state, a portion of the heat transferred to the surface of the electrostatic chuck 18 contributes to the temperature rise of the electrostatic chuck 18. The amount of heat contributing to the temperature rise of the electrostatic chuck 18 depends on the heat capacity of the electrostatic chuck 18. Therefore, 40% of the 60% of the heat transferred to the surface of the electrostatic chuck 18 is transferred to the heater HT. Therefore, when the temperature of the heater HT is controlled to be constant, the heater power supply HP is connected to the heater power P. h This causes the heater HT to generate "60" of heat.

[0076] In addition, Figure 5BIn the example set to a "steady state," heat of "80" is transferred from the plasma to the wafer W. The heat transferred to the wafer W is then transferred to the electrostatic chuck 18. Furthermore, when the temperature of the wafer W is in a steady state, the heat input and heat dissipation of the wafer W are equal. Therefore, the heat of "80" transferred from the plasma to the wafer W is transferred from the wafer W to the surface of the electrostatic chuck 18. The heat transferred to the surface of the electrostatic chuck 18 is then transferred to the heater HT. When the temperature of the electrostatic chuck 18 is in a steady state, the heat input and heat dissipation of the electrostatic chuck 18 are equal. Therefore, the heat of "80" transferred to the surface of the electrostatic chuck 18 is transferred to the heater HT. Therefore, when the temperature of the heater HT is controlled at a constant level, the heater power supply HP is connected to the heater power P. h This causes the heater HT to generate "20" of heat.

[0077] like Figure 5A and Figure 5B As shown, compared to the unignited state, the power supplied to the heater HT decreases in the ignition state. Furthermore, in the ignition state, the power supplied to the heater HT decreases until it reaches a stable state.

[0078] In addition, such as Figure 5A and Figure 5B As shown, when the temperature of the heater HT is controlled at a constant value, "100" of heat is dissipated from the heater HT by cooling from the base 20 in any of the following states: "unignition state," "transition state," and "stable state." That is, the heat flux q per unit area from the heater HT toward the refrigerant supplied to the refrigerant flow path 24 formed inside the base 20. sus The temperature gradient from the heater HT to the refrigerant is always constant. Therefore, the temperature sensor used to control the temperature of the heater HT to a constant value does not necessarily need to be directly mounted on the heater HT. For example, as long as it is between the heater HT and the refrigerant, such as on the back of the electrostatic chuck 18, in the adhesive layer 19, or inside the base 20, the temperature difference between the heater HT and the temperature sensor is always constant. The temperature difference (ΔT) between the temperature sensor and the heater HT is calculated using the temperature of the heater HT and the thermal conductivity and thermal resistance of the materials between them. The temperature difference (ΔT) is added to the temperature value detected by the temperature sensor, and this result can be output as the temperature of the heater HT, thus controlling the actual temperature of the heater HT to a constant value.

[0079] Figure 6 This is a diagram illustrating an example of the changes in temperature of wafer W and the power supplied to heater HT. Figure 6 (A) represents the temperature change of wafer W. Figure 6(B) represents the change in the power supplied to the heater HT. Figure 6 The example illustrates the measurement of the temperature of wafer W and the supply power to heater HT after igniting the plasma in an unignited state with the heater HT at a fixed temperature. The temperature of wafer W is measured using a temperature measuring wafer such as the Etch Temp, sold by KLA-Tencor.

[0080] Figure 6 During period T1, the plasma is in an unignited state where it is not ignited. During period T1, the power supplied to the heater HT is constant. Figure 6 During period T2, the plasma is in an ignition state and a transition state. During period T2, the power supplied to the heater HT decreases. Additionally, during period T2, the temperature of the wafer W rises to a fixed temperature. Figure 6 During period T3, the plasma is in an ignition state. During period T3, the temperature of wafer W is fixed and in a stable state. When the electrostatic chuck 18 is also in a stable state, the power supplied to heater HT is approximately fixed, and the decreasing tendency of the power supply is stable. Figure 6 During period T4, the plasma is extinguished and in an unignited state. During period T4, there is no heat input from the plasma to the wafer W, therefore the temperature of the wafer W decreases, and the power supplied to the heater HT increases.

[0081] exist Figure 6 During the transition state shown in T2, the tendency of the power supplied to the heater HT to decrease changes depending on the amount of heat input from the plasma to the wafer W, the thermal resistance between the surface of the wafer W and the electrostatic chuck 18, etc.

[0082] Figure 7 This is a diagram schematically illustrating an example of energy flow during ignition. Furthermore, Figure 7 These are all examples of transitional states. For example, in Figure 7 In the example where "heat input: small, thermal resistance: small" is set, "80" of the heat is transferred from the plasma to the wafer W. Of the "80" of heat transferred from the plasma to the wafer W, "60" of the heat is transferred from the wafer W to the surface of the electrostatic chuck 18. Furthermore, "40" of the "60" of heat transferred to the surface of the electrostatic chuck 18 is transferred to the heater HT. For example, when the temperature of the heater HT is controlled to be constant, the heater power supply HP is connected to the heater power P. h This causes the heater HT to generate "60" of heat.

[0083] In addition, Figure 7In the example where "heat input: large, thermal resistance: small", 100% of the heat is transferred from the plasma to the wafer W. Of the 100% of heat transferred from the plasma to the wafer W, 80% is transferred from the wafer W to the surface of the electrostatic chuck 18. Furthermore, 60% of the 80% of the heat transferred to the surface of the electrostatic chuck 18 is transferred to the heater HT. For example, when the temperature of the heater HT is controlled at a constant value, the heater power supply HP is connected via the heater power P. h The heater HT generates 40 degrees of heat.

[0084] In addition, Figure 7 In the example where "heat input: small, thermal resistance: large", 80% of the heat is transferred from the plasma to the wafer W. Of the 80% of heat transferred from the plasma to the wafer W, 40% is transferred from the wafer W to the surface of the electrostatic chuck 18. Of the 40% of heat transferred to the surface of the electrostatic chuck 18, 20% is transferred to the heater HT. For example, if the temperature of the heater HT is controlled at a constant value, the heater power supply HP is connected via the heater power P. h This generates 80 degrees of heat in the heater HT.

[0085] When the temperature of heater HT is controlled to be constant, the heater power P h The thermal resistance between the surface of wafer W and electrostatic chuck 18 changes depending on the amount of heat input from the plasma to wafer W. Therefore, in Figure 6 As shown in (B), the tendency for the power supplied to the heater HT to decrease during period T2 varies depending on factors such as the heat input from the plasma to the wafer W and the thermal resistance between the wafer W and the surface of the electrostatic chuck 18. Therefore, the curve of the power supplied to the heater HT during period T2 can be modeled using parameters such as the heat input from the plasma to the wafer W and the thermal resistance between the wafer W and the surface of the electrostatic chuck 18. In other words, the change in the power supplied to the heater HT during period T2 can be modeled using a computational formula with parameters such as the heat input from the plasma to the wafer W and the thermal resistance between the wafer W and the surface of the electrostatic chuck 18.

[0086] In this embodiment, Figure 6 The variation in the power supplied to the heater HT during period T2, as shown in (B), is modeled as an expression per unit area. For example, let t be the elapsed time from plasma ignition, and let the heater power P for elapsed time t be... h Let P be the value of P. h(t) The heat generated per unit area from heater HT is calculated for the presence of heat flux from the plasma over time t. h Let q be the value of q. h(t)In this case, the heat generated per unit area from the heater HT is the heat flux from the plasma after time t. h(t) It can be expressed as in equation (2) below. Additionally, the heat generated per unit area from the heater HT in a steady state when the plasma is not ignited and there is no heat flux from the plasma is q. h_Off It can be expressed as in equation (3) below. Additionally, the thermal resistance R per unit area between the surface of the electrostatic chuck 18 and the heater... thc • A can be expressed as in equation (4) below. The heat flux q in the case of plasma generation p The heat flux q when no plasma is generated p There are changes. This refers to the heat flux q per unit area from the plasma to the wafer W when plasma is generated. p Let the heat flux be q p_on The heat flux q per unit area from plasma to wafer W p_on And the thermal resistance R per unit area between the wafer W and the surface of the electrostatic chuck 18 th • When A is set as a parameter and a1, a2, a3, λ1, λ2, τ1, τ2 are expressed as equations (5)-(11) below, the heat generated per unit area from the heater HT when there is heat flux from the plasma is q. h(t) It can be expressed as in the following formula (1).

[0087] [Number 1]

[0088]

[0089] q h(t) =P h(t) / A…(2)

[0090] q h_off =P h_off / A…(3)

[0091]

[0092]

[0093]

[0094]

[0095]

[0096]

[0097]

[0098]

[0099] Here,

[0100] P h(t) P represents the heater power [W] when the heat flux from the plasma exists after time t. h_Off Heater power in steady state without heat flux from plasma [W / m] 2 ]. q h(t) The heat generated per unit area from heater HT when the heat flux from the plasma exists over time t [W / m²] 2 ].

[0101] q h_Off The heat generated per unit area from heater HT in steady state without heat flux from plasma [W / m²] 2 ].

[0102] R th • A represents the heat flux per unit area from plasma to wafer W [W / m²] 2 ].

[0103] R thc ·A is the thermal resistance per unit area between the surface of the electrostatic chuck 18 and the heater [K·m] 2 / W]. A is the area of ​​the region where the heater is located [m²]. 2 ].

[0104] ρ w The density of wafer W [kg / m³] 3 ].

[0105] C w The heat capacity per unit area of ​​wafer W [J / K·m] 2 ].

[0106] z w Let W be the thickness of the wafer [m].

[0107] ρ c The density of the ceramic constituting the electrostatic chuck 18 [kg / m³] 3 ].

[0108] C c The heat capacity per unit area of ​​the ceramic constituting the electrostatic chuck 18 [J / K·m] 2 ].

[0109] z c Let [m] be the distance from the surface of the electrostatic chuck 18 to the heater HT.

[0110] κc The thermal conductivity [W / K·m] of the ceramic that constitutes the electrostatic chuck 18.

[0111] t is the elapsed time [sec] from plasma ignition.

[0112] Regarding a1 in equation (5), 1 / a1 is a time constant representing the heating difficulty of wafer W. Furthermore, regarding a2 in equation (6), 1 / a2 is a time constant representing the input heat difficulty and heating difficulty of the electrostatic chuck 18. Furthermore, regarding a3 in equation (7), 1 / a3 is a time constant representing the penetration heat difficulty and heating difficulty of the electrostatic chuck 18.

[0113] The plasma processing device 10 can be used to determine the area A of the heater HT and the density ρ of the wafer W by measurement. w The heat capacity C per unit area of ​​wafer W w The thickness z of wafer W w The density ρ of the ceramic that constitutes the electrostatic chuck 18 c The heat capacity C per unit area of ​​the ceramic constituting the electrostatic chuck 18 c The distance z from the surface of the electrostatic chuck 18 to the heater HT c And the thermal conductivity κ of the ceramic constituting the electrostatic chuck 18 c The determination is based on the actual structures of the wafer W and the plasma processing device 10, respectively. This is based on the thermal conductivity κ. c Distance z c R is determined by equation (4). thc ·A.

[0114] The heater power P is given by the heat flux from the plasma at each elapsed time t from plasma ignition. h(t) And the heater power P in a steady state without heat flux from plasma h_Off Moreover, as shown in equations (2) and (3), the calculated heater power P is obtained by... h(t) and heater power P h_Off By dividing each by the area A of the heater HT, the heat generated per unit area from the heater HT when there is heat flux from the plasma can be calculated as q. h(t) And the heat output q per unit area from heater HT in steady state without heat flux from plasma. h_Off .

[0115] Furthermore, the heat flux q per unit area from the plasma to the wafer W can be determined by fitting the measurement results to equation (1). p_on And the thermal resistance R per unit area between the wafer W and the surface of the electrostatic chuck 18 th·A.

[0116] in addition, Figure 6 The temperature curve of wafer W during period T2 shown in (A) can also be modeled using parameters such as the heat input from the plasma to wafer W and the thermal resistance between the surface of wafer W and electrostatic chuck 18. In this embodiment, the temperature change of wafer W during period T2 is modeled as a formula per unit area. For example, the heat flux q per unit area from the plasma to wafer W is used as a formula. p_on And the thermal resistance R per unit area between the wafer W and the surface of the electrostatic chuck 18 th ·A is a parameter, and using a1, a2, a3, λ1, λ2, τ1, τ2 as shown in equations (5)-(11), the temperature T of the wafer W after time t is... W(t) [℃] can be expressed as in equation (12) below.

[0117] [Number 2]

[0118]

[0119] Here,

[0120] T W(t) The temperature [°C] of wafer W after time t.

[0121] T h To control the temperature [°C] of the heater HT, which is fixed.

[0122] The temperature T of the heater HT can be determined based on the actual conditions under which the temperature of wafer W is controlled at a constant level. h .

[0123] The heat flux q is obtained by fitting the measurement results to equation (1). p_on and thermal resistance R th In case A, the temperature T of wafer W can be calculated according to equation (12). W .

[0124] When the elapsed time t is sufficiently long compared to the time constants τ1 and τ2 expressed by equations (10) and (11), that is, when the calculation is performed from... Figure 6 During the period T2, which is the transition state, to the period T3, which is the steady state, the temperature T of wafer W is reduced. W The temperature T of the heater HT that becomes the target temperature h In the case of , equation (12) can be simplified to the following equation (13).

[0125] [Number 3]

[0126] T w(t) =T h +qp_on ·(R th ·A+R thc ·A)…(13)

[0127] For example, it is possible to determine the heater temperature T using equation (13). h Heat flux q p_on Thermal resistance R th ·A, R thc ·A is used to determine the temperature T of wafer W. W .

[0128] Furthermore, it is desirable for the plasma processing apparatus 10 to detect the state of the plasma during plasma processing in order to understand the status of the plasma processing. For example, it is desirable to detect the density distribution of the plasma in the plasma processing apparatus 10 as the state of the plasma. In the plasma processing apparatus 10, the amount of heat input from the plasma changes according to the density distribution of the plasma.

[0129] Figure 8 This is a diagram that schematically illustrates an example of the temperature changes in the unignited and transition states due to the plasma density distribution. Figure 8 The distribution of plasma density and the surface temperature changes of each segment of the stage 16 during plasma treatment are represented in (A) to (D) as time series. Figure 8 (A) indicates the unignited state. In the unignited state, no plasma is generated, and the temperature of each segment of the mounting region 18a is also fixed while controlling the power supplied to each heater HT to keep the temperature of each heater HT constant. Figure 8 (B) to (D) represent transition states. Regions with high plasma density experience greater heat input from the plasma to the mounting region 18a. Regions with low plasma density experience less heat input from the plasma to the mounting region 18a. For example, in the generated plasma density distribution as shown... Figure 8 As shown in (B) to (D), with the temperature high at the center and low at the periphery of the mounting region 18a, the heat input at the center of the mounting region 18a is greater. Therefore, the surface temperature at the center of the mounting region 18a also rises compared to the surrounding areas. By controlling the power supply to each heater HT to maintain a constant temperature for each heater HT, the increase in surface temperature of the mounting region 18a is reduced, thus decreasing the power supply to the heater HT. Because the heat input to the heater HT at the center of the mounting region 18a is greater, the power supply decreases significantly compared to the heaters HT in the surrounding areas.

[0130] Figure 9 This is a diagram schematically illustrating an example of energy flow in the unignited and transitional states. Furthermore, in Figure 9In the example, the mounting region 18a is divided into three regions: the central region (near the center of the mounting region 18a), the middle region (surrounding the central region), and the edge region (surrounding the middle region and near the edge of the mounting region 18a). It is assumed that the plasma density distribution is... Figure 8 Similarly, (B) to (D) are high at the center and low at the periphery of the placement area 18a.

[0131] exist Figure 9 In the unignited state shown, heat of "100" is dissipated from the heater HT by cooling from the base 20. For example, when the temperature of the heater HT is controlled at a constant level, the heater power supply HP is connected to the heater power P. h The heater HT generates "100" of heat. Thus, the heat generated by the heater HT is equal to the heat dissipated from the heater HT.

[0132] On the other hand, Figure 9 In the transition state shown, the plasma density distribution at the center of the mounting region 18a is higher than that at the periphery. Therefore, the heat input in the center of the mounting region 18a is "large", the heat input in the middle is "medium", and the heat input in the edge is "small". For example, if the thermal resistance of the center, the middle, and the edge is set to be the same, in the center, "100" of heat is input from the plasma, and "60" of heat is transferred to the heater HT. In the middle, "80" of heat is input from the plasma, and "40" of heat is transferred to the heater HT. In the edge, "40" of heat is input from the plasma, and "20" of heat is transferred to the heater HT.

[0133] Figure 10 This is a diagram illustrating an example of the change in temperature of wafer W and the supply power supplied to heater HT. Figure 10 (A) represents the temperature variation of the wafer W in the center, middle, and edge regions. Figure 10 (B) indicates the change in the power supplied to the heater HT from the central section, middle section, and edge section. For example... Figure 10As shown in (B), the waveform of the supplied power changes due to the amount of heat input. Therefore, by measuring the power supplied to the heater HT in each zone during the unignited state and the transition state, and fitting equation (1) using the measurement results of each zone, the amount of heat input in each zone can be determined. Furthermore, the density distribution of the plasma can be determined based on the amount of heat input in each zone. That is, the plasma processing apparatus 10 according to the embodiment can detect the state of the plasma without arranging sensors inside the processing container 12.

[0134] return Figure 3 The heater control unit 102a controls the temperature of each heater HT. For example, the heater control unit 102a outputs control data to the heater power supply HP, indicating the supply power to each heater HT, and controls the temperature of each heater HT by controlling the supply power from the heater power supply HP to each heater HT.

[0135] During plasma processing, a target temperature is set in the heater control unit 102a for each heater HT. For example, in the heater control unit 102a, for each segmented region of the mounting region 18a, the target temperature of the wafer W is set as the set temperature of the heater HT of that segmented region. The target temperature is, for example, the temperature at which the plasma etching of the wafer W achieves the optimal precision.

[0136] During plasma processing, the heater control unit 102a controls the power supplied to each heater HT to bring each heater HT to a set set temperature. For example, for each segmented region, the heater control unit 102a compares the temperature of each segmented region of the mounting area 18a, as shown by the temperature data input to the external interface 101, with the set temperature of that segmented region. Furthermore, the heater control unit 102a identifies segmented regions with temperatures lower than the set temperature and segmented regions with temperatures higher than the set temperature. The heater control unit 102a outputs control data to the heater power supply HP to increase the power supplied to segmented regions with temperatures lower than the set temperature and decrease the power supplied to segmented regions with temperatures higher than the set temperature.

[0137] The measurement unit 102b uses the power supply data input to the external interface 101 to show the power supply to each heater HT, and measures the power supply based on this power supply. For example, the measurement unit 102b controls the power supply to each heater HT via the heater control unit 102a to keep the temperature of each heater HT constant, and measures the power supply to each heater HT in the unignited state when the plasma is not ignited. In addition, the measurement unit 102b measures the power supply to each heater HT during the transition state from plasma ignition until the tendency of the power supply to each heater HT to decrease stabilizes.

[0138] For example, when the heater control unit 102a controls the power supplied to each heater HT to maintain a fixed set temperature for each heater HT, the measurement unit 102b measures the power supplied to each heater HT in the unignited state of the plasma before plasma processing begins. Additionally, the measurement unit 102b measures the power supplied to each heater HT in the transition state from plasma ignition until the tendency of the power supplied to each heater HT to decrease stabilizes. Regarding the power supplied to each heater HT in the unignited state, it is sufficient to measure at least once per heater HT, or multiple measurements can be performed and the average value set as the power supplied in the unignited state. Regarding the power supplied to each heater HT in the transition state, it is sufficient to measure twice or more. The measurement timing for the power supply is preferably when the tendency of the power supply to decrease is large. Furthermore, when the number of measurements is small, it is preferable to measure at a predetermined interval or longer. In this embodiment, the measurement unit 102b measures the power supplied to each heater HT at a predetermined period (e.g., a 0.1-second period) during plasma processing. Thus, the power supplied to each heater HT in multiple transition states is measured.

[0139] The measuring unit 102b measures the supply power supplied to each heater HT in the unignited state and the transition state at a predetermined cycle. For example, whenever the wafer W is replaced and the replaced wafer W is placed on the stage 16 for plasma processing, the measuring unit 102b measures the supply power supplied to each heater HT in the unignited state and the transition state. Alternatively, for example, whenever plasma processing is performed, the parameter calculation unit 102c may measure the supply power supplied to each heater HT in the unignited state and the transition state.

[0140] For each heater HT, the parameter calculation unit 102c calculates the heat input and thermal resistance using a calculation model that calculates the power supply for the transition state based on the heat input from the plasma and the thermal resistance between the wafer W and the heater HT. For example, the parameter calculation unit 102c uses the power supply for the ignition state and transition state measured by the measurement unit 102b to fit the calculation model to calculate the heat input and thermal resistance.

[0141] For example, the parameter calculation unit 102c calculates the heater power P in the unignited state for each heater HT after each elapsed time t. h_Off In addition, the parameter calculation unit 102c calculates the heater power P for each heater HT during the transition state at each elapsed time t. h(t) Furthermore, the parameter calculation unit 102c calculates the heater power P. h(t) and heater power P h_Off Divide by the area of ​​each heater HT to calculate the heat output q per unit area from heater HT in the unignited state after each time t. h_Off And the heat generated per unit area from heater HT for each transition state after time t. h(t) .

[0142] The parameter calculation unit 102c uses the above equations (1)-(11) as a calculation model to calculate the heat generation q from the heater HT per unit area for each time t elapsed for each heater HT. h(t) And the heat generated per unit area from heater HT q h_Off The heat flux q with the smallest fitting error is calculated. p_on and thermal resistance R th ·A.

[0143] The parameter calculation unit 102c can calculate the heat flux q according to a specified cycle using the measured power supply in the unignited state and the transient state. p_on and thermal resistance R th • A. For example, whenever wafer W is replaced, the parameter calculation unit 102c uses the power supplied in the un-ignition state and the transition state, measured while the wafer W is placed on the mounting stage 16, to calculate the heat flux q. p_on and thermal resistance R th A. Furthermore, for example, whenever plasma processing is performed, the parameter calculation unit 102c uses the supplied power in the unignited state and the transition state to calculate the heat flux q. p_on and thermal resistance R th ·A.

[0144] The output unit 102d controls the output of various information. For example, the output unit 102d outputs information at a predetermined period based on the heat flux q calculated by the parameter calculation unit 102c. p_on To output information. For example, output unit 102d is based on the heat flux q of each heater HT calculated by parameter calculation unit 102c. p_on The output unit 102d outputs information representing the plasma density distribution to the user interface 103. For example, whenever wafer W is replaced, the output unit 102d outputs information representing the plasma density distribution when the wafer W has undergone plasma treatment to the user interface 103. In addition, the output unit 102d can output the information representing the plasma density distribution as data to an external device.

[0145] Figure 11A This is a graph illustrating an example of the output representing information about the density distribution of the plasma. Figure 11A In the example, for each segmented region of the mounting area 18a equipped with heater HT, the heat flux q of that segmented region is displayed by a pattern. p_on .

[0146] Figure 11B This is a graph illustrating an example of the output representing information about the density distribution of the plasma. Figure 11B In the example, q represents the heat flux of the center, middle, and edge. p_on .

[0147] Therefore, the process manager and the manager of the plasma processing device 10 can grasp the state of the plasma.

[0148] Furthermore, the plasma processing apparatus 10 may experience abnormal plasma conditions. For example, the plasma processing apparatus 10 may experience an abnormal state where the plasma is unsuitable for plasma processing due to changes in the characteristics of the processing container 12 caused by significant wear of the electrostatic chuck 18 or the adhesion of deposits. Additionally, the plasma processing apparatus 10 may also experience issues with the loading of abnormal wafers W.

[0149] Therefore, the alarm unit 102e issues an alarm based on the heat input or changes in heat input calculated by the parameter calculation unit 102c at a predetermined period. For example, the alarm unit 102e uses the heat flux q calculated by the parameter calculation unit 102c at a predetermined period. p_on An alarm is triggered when the condition exceeds the specified allowable range. Furthermore, the alarm unit 102e calculates the heat flux q at a predetermined cycle using the parameter calculation unit 102c. p_onAn alarm is triggered if the change exceeds the specified tolerance value. The alarm can be of any type, as long as it can notify the process manager, the manager of the plasma processing unit 10, etc. For example, the alarm unit 102e displays a message to notify the user interface 103 of the anomaly.

[0150] Therefore, the plasma processing apparatus 10 according to this embodiment can report the occurrence of an anomaly when the plasma state is abnormal due to the characteristics of the processing container 12, the abnormal loading of a wafer W, etc.

[0151] The modification unit 102f modifies the control parameters of the plasma processing based on information representing the density distribution of the plasma, so as to equalize the plasma processing for the wafer W.

[0152] Here, plasma etching includes factors such as surface adsorption of free radicals, thermal desorption, and ion collision-based desorption. Figure 12 This is a schematic diagram illustrating plasma etching. Figure 12 In the example, the state of plasma etching of the organic film surface by O2 gas is modeled. The surface of the organic film is etched through the synergistic effect of O radical adsorption, thermal desorption, and ion collision-based desorption.

[0153] The etching rate (E / R) of plasma etching can be expressed by the following equation (14).

[0154] [Number 4]

[0155]

[0156] Here,

[0157] n c This represents the material of the etched film.

[0158] Γ radical This refers to the supply of free radicals.

[0159] S represents the adsorption probability on the surface.

[0160] K d This represents the thermal reaction rate.

[0161] Γ ion This represents the ion incident amount.

[0162] E i It refers to ion energy.

[0163] K is the reaction probability of ion desorption.

[0164] Equation (14) "K dThe part "kE" indicates desorption based on thermal energy. i ·Γ ion The part "s·Γ" indicates desorption based on ion collisions. radical The part marked "" indicates the surface adsorption of free radicals.

[0165] The plasma concentration distribution affects ion collision-based desorption, as shown in equation (14) with "kE". i ·Γ ion The etch rate varies depending on the plasma concentration. The etching rate also varies depending on the K... d The part of "s·Γ" radical The portion of "K" changes. Therefore, by changing "K" in accordance with the density distribution of the plasma... d The part of "s·Γ" radical The part that enables the etching rate to be equalized. The modification unit 102f modifies the "K" based on information representing the density distribution of the plasma. d The part of "s·Γ" radical The control parameters of the plasma processing that affect the part of the process are used to equalize the plasma processing for wafer W.

[0166] For example, "K" d The part "" changes, for example, according to the temperature of the wafer W. Additionally, "s·Γ" radical The percentage of "" varies depending on the concentration of the gas that forms the plasma.

[0167] The modification unit 102f modifies the target temperature of the wafer W in each segmented region of the mounting region 18a based on information representing the plasma density distribution. For example, the modification unit 102f modifies the target temperature for segmented regions with high plasma density to reduce thermal desorption. For example, the modification unit 102f modifies the target temperature to a lower value. Conversely, the modification unit 102f modifies the target temperature for segmented regions with low plasma density to increase thermal desorption. For example, the modification unit 102f modifies the target temperature to a higher value. Furthermore, when the upper electrode 30 is configured to change the concentration of the ejected gas for each segmented region formed by dividing the lower surface, the modification unit 102f can modify the concentration of the ejected gas for each segmented region of the upper electrode 30 based on information representing the plasma density distribution. For example, the modification unit 102f modifies the gas concentration in segmented regions with high plasma density to a lower value. Conversely, the modification unit 102f modifies the gas concentration in segmented regions with low plasma density to a higher value. The modification unit 102f can combine the adjustment of the target temperature of the wafer W for each segmented region and the adjustment of the concentration of the ejected gas for each segmented region of the upper electrode 30.

[0168] The temperature setting calculation unit 102g calculates the set temperature of the heater HT that makes the wafer W reach the target temperature for each heater HT using the calculated heat input and thermal resistance. For example, the temperature setting calculation unit 102g calculates the heat flux q for each heater HT. p_on and thermal resistance R th Substitute A into equations (5), (6), and (12). Furthermore, the temperature calculation unit 102g calculates the temperature T of the wafer W for each heater HT using a1, a2, a3, λ1, λ2, τ1, and τ2 as shown in equations (5)-(11) and according to equation (12). W The temperature T of the heater HT that becomes the target temperature h For example, the temperature calculation unit 102g sets the elapsed time t to a predetermined value that can be considered a stable state, and calculates the temperature T of the wafer W. W The temperature T of the heater HT that becomes the target temperature h The calculated temperature T of the heater HT. h The temperature of the heater HT is required to bring the temperature of wafer W to the target temperature. Furthermore, the temperature T of the heater HT that brings the temperature of wafer W to the target temperature can be calculated using equation (13). h .

[0169] Furthermore, the temperature calculation unit 102g can calculate the current temperature T of the heater HT according to formula (12) as follows. h The temperature T of the wafer W at that time W For example, the temperature calculation unit 102g calculates the current temperature T of the heater HT. h The temperature T of wafer W is determined when the elapsed time t is set to a specified value that can be considered as the magnitude of a steady state. W Next, the temperature calculation unit 102g calculates the temperature T calculated by the unit. W The difference ΔT from the target temperature W Furthermore, the temperature calculation unit 102g can calculate the temperature T from the current heater HT. h Subtract the difference ΔT W The obtained temperature is used as the temperature of the heater HT to bring the temperature of wafer W to the target temperature.

[0170] The temperature calculation unit 102g corrects the set temperature of each heater HT in the heater control unit 102a to the temperature of the heater HT that makes the temperature of the wafer W the target temperature.

[0171] The temperature calculation unit 102g calculates the temperature of the heater HT that brings the temperature of wafer W to the target temperature at a predetermined cycle, and corrects the set temperature of each heater HT. For example, whenever wafer W is replaced, the temperature calculation unit 102g calculates the temperature of the heater HT that brings the temperature of wafer W to the target temperature, and corrects the set temperature of each heater HT. Alternatively, for example, whenever plasma processing is performed, the temperature calculation unit 102g calculates the temperature of the heater HT that brings the temperature of wafer W to the target temperature, and corrects the set temperature of each heater HT.

[0172] Therefore, the plasma processing apparatus 10 according to this embodiment can control the temperature of the wafer W in plasma processing to the target temperature with high precision.

[0173] [Control Flow]

[0174] Next, the plasma state detection method using the plasma processing apparatus 10 according to this embodiment will be described. Figure 13 This is a flowchart illustrating an example of the process for plasma state detection and plasma state control according to the embodiment. This process is executed at a predetermined time, such as the time when plasma processing begins.

[0175] The heater control unit 102a controls the power supplied to each heater HT so that each heater HT reaches the set temperature (step S10).

[0176] While the heater control unit 102a controls the power supplied to each heater HT to make the temperature of each heater HT a fixed set temperature, the measuring unit 102b measures the power supplied to each heater HT in the unignited state and the transition state (step S11).

[0177] The parameter calculation unit 102c calculates the heat input and thermal resistance for each heater HT by fitting a calculation model with the heat output per unit area from the heater HT, which is obtained by dividing the measured power supplied in the unignited state and the transition state by the area of ​​the heater HT (step S12). For example, the parameter calculation unit 102c uses the above equations (1)-(11) as the calculation model and calculates the heat output per unit area from the heater HT q for each heater HT at each elapsed time t. h(t) and the heat generated per unit area from heater HT q h_Off The heat flux q with the smallest fitting error is calculated. p_on and thermal resistance R th ·A.

[0178] The output unit 102d outputs information based on the input quantity calculated by the parameter calculation unit 102c (step S13). For example, the output unit 102d outputs information based on the heat flux q of each heater HT calculated by the parameter calculation unit 102c. p_on This is used to output information representing the density distribution of the plasma to the user interface 103.

[0179] The modification unit 102f modifies the control parameters of the plasma processing based on information representing the plasma density distribution, so as to homogenize the plasma processing for the wafer W (step S14). For example, the modification unit 102f modifies the target temperature of the wafer W in each segment of the mounting region 18a based on information representing the plasma density distribution.

[0180] The temperature calculation unit 102g calculates the set temperature of the heater HT that makes the wafer W reach the target temperature for each heater HT using the calculated heat input and thermal resistance (step S15). For example, the temperature calculation unit 102g calculates the heat flux q for each heater HT. p_on and thermal resistance R th Substitute A into equations (5), (6), and (12). Furthermore, the temperature calculation unit 102g uses a1, a2, a3, λ1, λ2, τ1, and τ2 shown in equations (5)-(11) to calculate the temperature T of the wafer W according to equation (12). W The temperature T of the heater HT that becomes the target temperature h Furthermore, the temperature T of the heater HT that makes the temperature of wafer W reach the target temperature can be determined according to equation (13). h .

[0181] The temperature calculation unit 102g corrects the set temperature of each heater HT in the heater control unit 102a to the set temperature of the heater HT that makes the temperature of the wafer W the target temperature (step S16), and ends the process.

[0182] As such, the plasma processing apparatus 10 according to this embodiment includes a stage 16, a heater control unit 102a, a measurement unit 102b, a parameter calculation unit 102c, and an output unit 102d. The stage 16 is equipped with a heater HT, the temperature of which can be adjusted for mounting the wafer W. The heater control unit 102a controls the power supplied to the heater HT to bring the heater HT to a set temperature. The measurement unit 102b, through the heater control unit 102a, controls the power supplied to the heater HT to keep the temperature of the heater HT constant, and measures the power supplied in the unignited state (when the plasma is not ignited) and the power supplied in the transition state (when the power supplied to the heater HT decreases from the ignition of the plasma). The parameter calculation unit 102c uses the power supplied in the unignited state and the transition state measured by the measurement unit 102b to fit a calculation model to calculate the heat input from the plasma. This calculation model includes the heat input as a parameter to calculate the power supplied in the transition state. The output unit 102d outputs information based on the heat input calculated by the parameter calculation unit 102c. Therefore, the plasma processing device 10 can detect the state of the plasma without installing sensors inside the processing container 12.

[0183] Furthermore, the plasma processing apparatus 10 of this embodiment is provided with a separate heater HT for each region divided by the mounting surface of the stage 16. The heater control unit 102a controls the power supply to each heater HT so that the heater HT provided for each region reaches a set temperature for each region. The measurement unit 102b, through the heater control unit 102a, controls the power supply to each heater HT to fix the temperature, and measures the power supply in the unignited state and the transition state for each heater HT. The parameter calculation unit 102c, for each heater HT, uses the power supply in the unignited state and the transition state measured by the measurement unit 102b to fit a calculation model to calculate the heat input for each heater HT. The output unit 102d outputs information representing the plasma density distribution based on the heat input calculated by the parameter calculation unit 102c for each heater HT. Thus, the plasma processing apparatus 10 can provide information representing the plasma density distribution during plasma processing without placing sensors inside the processing container 12.

[0184] Furthermore, the plasma processing apparatus 10 according to this embodiment also includes a modification unit 102f. The modification unit 102f modifies the control parameters of the plasma processing based on the plasma density distribution to homogenize the plasma processing for the wafer W. Thus, the plasma processing apparatus 10 is capable of homogenizing the plasma processing for the wafer W.

[0185] Furthermore, the plasma processing apparatus 10 according to this embodiment also includes an alarm unit 102e. The alarm unit 102e issues an alarm based on information output by the output unit 102d or changes in that information. Therefore, the plasma processing apparatus 10 can issue an alarm when an abnormality occurs in the plasma state.

[0186] The embodiments have been described above, but it should be considered that the embodiments disclosed herein are illustrative in all respects and not restrictive. In fact, the above embodiments can be implemented in various ways. Furthermore, the above embodiments can be omitted, substituted, or modified in various ways without departing from the claims and their spirit.

[0187] For example, in the above embodiment, plasma processing of a semiconductor wafer, which is the object to be processed, was described as an example, but it is not limited to this. As long as the object to be processed is affected by temperature, the progress of plasma processing can be any object. For example, the object to be processed can be a glass substrate, etc.

[0188] Furthermore, in the above embodiments, plasma etching was used as an example of plasma treatment, but the method is not limited to this. Plasma treatment can be any treatment performed using plasma. Examples of plasma treatments include chemical vapor deposition (CVD), atomic layer deposition (ALD), ashing, plasma doping, and plasma annealing.

[0189] Furthermore, in the above embodiment, the base 20 of the plasma processing apparatus 10 is connected to a first high-frequency power supply HFS for generating plasma and a second high-frequency power supply LFS for bias power, but this is not a limitation. The first high-frequency power supply HFS for generating plasma may also be connected to the upper electrode 30 via a matching converter MU.

[0190] Furthermore, in the above embodiment, the plasma processing apparatus 10 is a capacitively coupled parallel-plate plasma processing apparatus, but any plasma processing apparatus can be used. For example, the plasma processing apparatus 10 can be any type of plasma processing apparatus, such as an inductively coupled plasma processing apparatus or a plasma processing apparatus that uses surface waves such as microwaves to excite the gas.

[0191] Furthermore, in the above embodiment, the example described is the case where the changing unit 102f changes the target temperature of the wafer W in each segment of the mounting region 18a based on information indicating the plasma density distribution, but it is not limited to this. For example, if configured to change the plasma density distribution during plasma generation for each segmented region or approximately each segmented region into which the lower surface of the upper electrode 30 is divided, the changing unit 102f can change the plasma density for each segment where plasma generation is performed based on information indicating the plasma density distribution. Furthermore, regarding the structure capable of changing the plasma density distribution for each segmented region, as an example, in the case of a capacitively coupled parallel-plate plasma processing apparatus, the structure is as follows: the upper electrode 30 is divided into each segmented region, and multiple first high-frequency power supplies HFS capable of generating different high-frequency power are connected to each segmented upper electrode. In the case of an inductively coupled plasma processing apparatus, the structure is as follows: the antenna for generating plasma is divided into each segmented region, and multiple first high-frequency power supplies HFS capable of generating different high-frequency power are connected to each segmented antenna.

[0192] Furthermore, in the above embodiment, the example described is that a heater HT is provided in each of the segmented regions into which the mounting region 18a of the mounting stage 16 is divided, but this is not a limitation. A heater HT can be provided in the entire mounting region 18a of the mounting stage 16, and the supply power supplied to the heater HT in the unignited state and the transition state can be measured. The heat input is calculated by fitting the measurement results to a calculation model. The calculated heat input is the overall heat input of the plasma, therefore the overall state of the plasma can be detected based on the calculated heat input.

[0193] Furthermore, in the above-described embodiments, such as Figure 2 As shown, the example described is the case where the placement area 18a of the placement platform 16 is divided into a central circular area and a plurality of concentric annular areas surrounding the circular area, but it is not limited to this. Figure 14 This is a top view showing an example of the division of the mounting surface of the platform according to the embodiment. For example, as... Figure 14 As shown, the mounting area 18a of the mounting stage 16 can be divided into a lattice shape, and a heater HT can be installed in each segmented area. This allows for the detection of heat input in each segmented area of ​​the lattice shape, enabling a more detailed determination of the plasma density distribution.

[0194] Explanation of reference numerals in the attached figures

[0195] 10: Plasma processing apparatus; 16: Stage; 18: Electrostatic chuck; 18a: Placement area; 20: Base; 100: Control unit; 102: Process controller; 102a: Heater control unit; 102b: Measurement unit; 102c: Parameter calculation unit; 102d: Output unit; 102e: Alarm unit; 102f: Change unit; 102g: Set temperature calculation unit; HP: Heater power supply; HT: Heater; PD: Power detection unit; TD: Temperature measuring device; W: Wafer.

Claims

1. A plasma processing device, comprising: A stage is provided with a heater, which is capable of adjusting the temperature of the mounting surface used to mount the object to be processed as a plasma treatment. A heater control unit controls the power supplied to the heater so that the heater reaches a set temperature; The measuring unit controls the power supplied to the heater by the heater control unit to keep the temperature of the heater constant. The measuring unit measures the power supplied to the heater in the unignited state when the plasma is not ignited and in the ignited state after the plasma is ignited. The parameter calculation unit uses the heat input from the plasma as a parameter and calculates the heat input using the power supplied in the unignited state and the ignition state as measured by the measurement unit. as well as The output unit outputs information based on the amount of heat input calculated by the parameter calculation unit.

2. The plasma processing apparatus according to claim 1, characterized in that, In the mounting platform, the heater is individually provided for each region obtained by dividing the mounting surface. The heater control unit controls the supply of power to each heater so that the heater installed in each area reaches a set temperature in each area. The heater control unit controls the power supply to each heater to maintain a constant temperature, and the measuring unit measures the power supply to each heater in both the unignited and ignited states. The parameter calculation unit calculates the heat input for each heater using the power supplied in the non-ignition and ignition states as measured by the measurement unit. The output unit outputs information representing the density distribution of the plasma based on the heat input of each heater calculated by the parameter calculation unit.

3. The plasma processing apparatus according to claim 2, characterized in that, It also includes a modification unit that modifies the control parameters of the plasma treatment based on the density distribution of the plasma, so as to equalize the plasma treatment for the object being treated.

4. The plasma processing apparatus according to any one of claims 1 to 3, characterized in that, It also has an alarm unit that generates an alarm based on information output by the output unit or changes in that information.

5. The plasma processing apparatus according to claim 1, characterized in that, The measuring unit measures the power supplied to the heater in the unignited state and the ignition state at a predetermined period. The parameter calculation unit calculates the heat input in each cycle using the power supplied in the non-ignition and ignition states as measured by the measurement unit.

6. The plasma processing apparatus according to claim 1, characterized in that, During plasma treatment, the measuring unit measures the power supplied to the heater in both the unignited and ignited states. Whenever plasma processing is performed, the parameter calculation unit uses the power supplied in the unignited state and the ignition state as measured by the measurement unit to calculate the heat input.

7. The plasma processing apparatus according to claim 1, characterized in that, The ignition state after plasma ignition is the transition state from the plasma ignition onwards, when the power supplied to the heater decreases.

8. The plasma processing apparatus according to claim 7, characterized in that, The measuring unit will measure the power supplied to the heater in the transition state more than twice.

9. The plasma processing apparatus according to claim 3, characterized in that, The modification unit changes the target temperature of the wafer in each segment of the mounting region based on information representing the plasma density distribution.

10. The plasma processing apparatus according to claim 3, characterized in that, The modification unit adjusts the concentration of the ejected gas for each segmented region of the upper electrode based on information representing the plasma density distribution.

11. The plasma processing apparatus according to claim 2, characterized in that, The mounting platform is equipped with a temperature sensor capable of detecting the temperature of the heater in each region obtained by dividing the mounting surface.

12. The plasma processing apparatus according to claim 11, characterized in that, The temperature sensor is installed on the heater.

13. The plasma processing apparatus according to claim 11, characterized in that, The temperature sensor is positioned between the heater and the refrigerant.

14. The plasma processing apparatus according to claim 2, characterized in that, The mounting surface of the mounting platform is divided into multiple regions along the circumference.

15. The plasma processing apparatus according to claim 14, characterized in that, The closer the mounting surface is to the outer periphery, the narrower the radial width of the plurality of regions.

16. A method for detecting plasma state, characterized in that, The computer performs the following processing: The power supplied to the heater is controlled to maintain a constant temperature, and the power supplied is measured in both the unignited state (before plasma ignition) and the ignited state (after plasma ignition). The heater is mounted on a stage, and the temperature of the mounting surface used to mount the object to be processed as plasma is adjustable. The heat input from the plasma is used as a parameter, and the measured power supply in both the unignited and ignited states is used to calculate the heat input. The output is based on the calculated heat input.

17. A plasma state detection program, characterized in that, The computer will perform the following processes: The power supplied to the heater is controlled to maintain a constant temperature, and the power supplied is measured in both the unignited state (before plasma ignition) and the ignited state (after plasma ignition). The heater is mounted on a stage, and the temperature of the mounting surface used to mount the object to be processed as plasma is adjustable. The heat input from the plasma is used as a parameter, and the measured power supply in both the unignited and ignited states is used to calculate the heat input. The output is based on the calculated heat input.

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