Plasma processing device, plasma state detection method, and plasma state detection program

Abstract

The measurement unit controls the power supplied to the heater by the heater control unit so that the temperature of the heater becomes constant, and measures the power supplied in the non-ignition state where the plasma is not ignited and in the transient state where the power supplied to the heater decreases after the plasma is ignited. The parameter calculation unit includes the amount of heat input from the plasma as a parameter and calculates the amount of heat input by performing fitting on a calculation model that calculates the power supplied in the transient state using the power supplied in the non-ignition state and the transient state measured by the measurement unit. The output unit outputs information based on the amount of heat input calculated by the parameter calculation unit.

Description

Technology Field

[0001] The present disclosure relates to a plasma processing apparatus, a plasma state detection method, and a plasma state detection program. Background Technology

[0002] Conventionally, a plasma processing apparatus is known for performing plasma processing, such as etching, on a workpiece such as a semiconductor wafer (hereinafter also referred to as a "wafer") using plasma. In this plasma processing apparatus, a technology has been proposed to detect the state of the plasma by placing sensors, such as various probes or various electrical sensors, inside the processing vessel. Prior art literature

[0003] Japanese Patent Publication No. 2009-194032 Japanese Patent Publication No. 2009-087790 Japanese Patent Publication No. 2014-513390 The problem to be solved

[0004] The present disclosure provides a technique for detecting the state of plasma without deploying a sensor. means of solving the problem

[0005] A plasma processing apparatus according to one embodiment of the present disclosure comprises a loading platform, a heater control unit, a measuring unit, a parameter calculation unit, and an output unit. The loading platform is provided with a heater capable of adjusting the temperature of the loading surface on which a workpiece to be processed for plasma processing is loaded. The 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 so that the temperature of the heater becomes constant by the heater control unit, and measures the power supplied in a non-ignited state where the plasma is not ignited, and in a transient state where the power supplied to the heater decreases after the plasma is ignited. The parameter calculation unit includes the amount of heat input from the plasma as a parameter, and calculates the amount of heat input by performing fitting on a calculation model that calculates the power supplied in the transient state using the power supplied in the non-ignited state and the transient state measured by the measuring unit. The output unit outputs information based on the amount of heat input calculated by the parameter calculation unit. Effects of the invention

[0006] According to the present disclosure, the state of the plasma can be detected without placing a sensor inside the processing vessel. Brief explanation of the drawing

[0007] FIG. 1 is a cross-sectional view illustrating an example of the schematic configuration of a plasma processing device according to an embodiment. FIG. 2 is a plan view illustrating an example of the configuration of a loading platform according to an embodiment. FIG. 3 is a block diagram illustrating an example of the schematic configuration of a control unit that controls a plasma processing device according to an embodiment. Figure 4 is a schematic diagram illustrating an example of the flow of energy affecting the temperature of a wafer. Figure 5a is a schematic diagram illustrating an example of the flow of energy in an unignited state. Figure 5b is a diagram schematically illustrating an example of the flow of energy in an ignition state. Figure 6 is a diagram illustrating an example of the change in temperature of the wafer (W) and the power supplied to the heater (HT). Figure 7 is a diagram schematically illustrating an example of the flow of energy in an ignition state. Figure 8 is a schematic diagram illustrating an example of temperature change between the unignited state and the transient state due to the density distribution of the plasma. Figure 9 is a diagram schematically illustrating an example of the flow of energy in the unignited state and the transient state. FIG. 10 is a diagram illustrating an example of the change in temperature of the wafer (W) and the power supplied to the heater (HT). Figure 11a is a diagram illustrating an example of the output of information showing the density distribution of a plasma. Figure 11b is a diagram illustrating an example of the output of information showing the density distribution of the plasma. Figure 12 is a schematic diagram illustrating plasma etching. FIG. 13 is a flowchart showing an example of the flow of plasma state detection and plasma state control according to an embodiment. FIG. 14 is a plan view illustrating an example of the division of the loading surface of a loading platform according to an embodiment. Specific details for implementing the invention

[0008] Hereinafter, embodiments of the plasma processing apparatus, plasma state detection method, and plasma state detection program disclosed herein will be described in detail with reference to the drawings. Furthermore, the plasma processing apparatus, plasma state detection method, and plasma state detection program disclosed herein are not limited by these embodiments.

[0009] However, for example, in plasma processing devices, sensors such as various probes or electrical sensors are placed inside the processing vessel to detect the state of the plasma. However, if sensors are placed inside the processing vessel, particularly in a location close to the plasma generation area, the state of the plasma changes due to the influence of the sensors. Consequently, there is a risk that the characteristics or uniformity of the plasma processing on the film to be treated may be affected in the plasma processing device. Furthermore, there is a risk that particles or abnormal discharges may occur in the plasma processing device. Additionally, if sensors are placed inside the processing vessel, plasma processing may not be possible on the film to be treated. In such a case, the plasma processing device cannot detect the state of the plasma while the plasma processing is actually being performed. Therefore, there is an expectation to detect the state of the plasma without placing sensors inside the processing vessel.

[0010] [Configuration of Plasma Processing Device]

[0011] First, the configuration of the plasma processing device (10) according to the embodiment will be described. FIG. 1 is a cross-sectional view illustrating an example of the schematic configuration of the plasma processing device according to the embodiment. The plasma processing device (10) shown in FIG. 1 is a capacitively coupled parallel plate plasma etching device. The plasma processing device (10) is equipped with a roughly cylindrical processing vessel (12). The processing vessel (12) is made of, for example, aluminum. In addition, the surface of the processing vessel (12) is subjected to anodizing treatment.

[0012] A loading platform (16) is provided within the processing vessel (12). The loading platform (16) includes an electrostatic chuck (18) and a base (20). The upper surface of the electrostatic chuck (18) serves as a loading surface for loading a workpiece to be processed by plasma treatment. In this embodiment, a wafer (W) is loaded onto the upper surface of the electrostatic chuck (18) as the workpiece. The base (20) has a roughly disc shape and is composed of a conductive metal, such as aluminum, in its main part. The base (20) forms a lower electrode. The base (20) is supported by a support member (14). The support member (14) is a cylindrical member extending from the bottom of the processing vessel (12).

[0013] A first high-frequency power supply (HFS) is electrically connected to the base (20). The first high-frequency power supply (HFS) is a power supply that generates high-frequency power for plasma generation, and generates high-frequency power of 27 to 100 MHz, for example, 40 MHz. By doing so, plasma is generated directly above the base (20). The matching device (MU1) has a circuit for matching the output impedance of the first high-frequency power supply (HFS) with the input impedance of the load side (base (20) side).

[0014] Additionally, a second high-frequency power supply (LFS) is electrically connected to the base (20) through a matching unit (MU2). The second high-frequency power supply (LFS) generates high-frequency power (high-frequency bias power) for introducing ions into the wafer (W) and supplies the said high-frequency bias power to the base (20). By doing so, a bias potential is created in the base (20). The frequency of the high-frequency bias power is a frequency within the range of 400 kHz to 13.56 MHz, and in one example, 3 MHz. The matching unit (MU2) has a circuit for matching the output impedance of the second high-frequency power supply (LFS) with the input impedance of the load side (base (20) side).

[0015] An electrostatic chuck (18) is provided on the base (20). The electrostatic chuck (18) adsorbs a wafer (W) by an electrostatic force such as Coulomb force and holds and supports the wafer (W). The electrostatic chuck (18) has an electrostatic adsorption electrode (E1) within a ceramic body. A DC power source (22) is electrically connected to the electrode (E1) through a switch (SW1). The adsorption force holding and supporting the wafer (W) depends on the value of the DC voltage applied from the DC power source (22).

[0016] A focus ring (FR) is provided on the upper surface of the base (20) and also around the electrostatic chuck (18). The focus ring (FR) is provided to improve the uniformity of the plasma treatment. The focus ring (FR) is made of a material appropriately selected according to the plasma treatment to be performed, and may be made of, for example, silicon or quartz.

[0017] A refrigerant flow path (24) is formed inside the base (20). Refrigerant is supplied to the refrigerant flow path (24) through a pipe (26a) from a chiller unit provided outside the processing container (12). The refrigerant supplied to the refrigerant flow path (24) is configured to return to the chiller unit through a pipe (26b). In addition, details of the loading platform (16), including the base (20) and the electrostatic chuck (18), will be described later.

[0018] An upper electrode (30) is provided inside the processing container (12). The upper electrode (30) is positioned opposite the base (20) above the loading platform (16), and the base (20) and the upper electrode (30) are arranged approximately parallel to each other.

[0019] The upper electrode (30) is supported on the upper part of the processing vessel (12) through 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 provides a plurality of gas discharge holes (34a). The electrode plate (34) may be composed of a low-resistance conductor or semiconductor with low Joule heat.

[0020] The electrode support (36) is configured to detachably support the electrode plate (34) and may be composed of a conductive material, such as aluminum. The electrode support (36) may have a water-cooling structure. A gas diffusion chamber (36a) is provided inside the electrode support (36). A plurality of gas flow holes (36b) communicating with a gas discharge hole (34a) extend downward from the gas diffusion chamber (36a). Additionally, a gas inlet port (36c) is formed in the electrode support (36) to guide the processing gas into the gas diffusion chamber (36a), and a gas supply pipe (38) is connected to the gas inlet port (36c).

[0021] A gas source group (40) is connected to the gas supply pipe (38) through a valve group (42) and a flow controller group (44). The valve group (42) has a plurality of open / close valves, and the flow controller group (44) has a plurality of flow controllers, such as a mass flow controller. Additionally, the gas source group (40) has a plurality of gas sources for gases required for plasma processing. The plurality of gas sources of the gas source group (40) are connected to the gas supply pipe (38) through corresponding open / close valves and corresponding mass flow controllers.

[0022] In the plasma processing device (10), one or more gases from one or more selected gas sources among a plurality of gas sources of a 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 discharged into the processing space (S) through the gas flow hole (36b) and the gas discharge hole (34a).

[0023] Additionally, as illustrated in FIG. 1, the plasma processing device (10) may further be provided with a grounding conductor (12a). The grounding conductor (12a) is a roughly cylindrical grounding conductor and is provided to extend upward from the side wall of the processing vessel (12) above the height position of the upper electrode (30).

[0024] In addition, in the plasma processing device (10), a deposition shield (46) is detachably provided along the inner wall of the processing vessel (12). Additionally, the deposition shield (46) is also provided on the outer circumference of the support member (14). The deposition shield (46) prevents etching byproducts (deposition) from adhering to the processing vessel (12) and can be constructed by coating an aluminum material with ceramics such as Y2O3.

[0025] At the bottom side of the processing vessel (12), an exhaust plate (48) is provided between the support member (14) and the inner wall of the processing vessel (12). The exhaust plate (48) can be constructed, for example, by coating an aluminum material with a ceramic such as Y2O3. Below the exhaust plate (48), an exhaust port (12e) is provided in the processing vessel (12). An exhaust device (50) is connected to the exhaust port (12e) through an exhaust pipe (52). The exhaust device (50) has a vacuum pump such as a turbo molecular pump and can reduce the pressure inside the processing vessel (12) to a desired vacuum level. Additionally, an inlet / outlet port (12g) for a wafer (W) is provided on the side wall of the processing vessel (12), and the inlet / outlet port (12g) can be opened and closed by a gate valve (54).

[0026] The plasma processing device (10) configured as described above has its operation comprehensively controlled by a control unit (100). The control unit (100) is, for example, a computer and controls each part of the plasma processing device (10). The plasma processing device (10) has its operation comprehensively controlled by a control unit (100).

[0027] [Composition of the storage rack]

[0028] Next, the loading platform (16) will be described in detail. FIG. 2 is a plan view illustrating an example of the configuration of the loading platform according to an embodiment. As described above, the loading platform (16) has an electrostatic chuck (18) and a base (20). The electrostatic chuck (18) has a main body (18m) made of ceramic. The main body (18m) has a roughly disc shape. The main body (18m) provides a loading area (18a) and an outer periphery area (18b). The loading area (18a) is a roughly circular area when viewed in a planar view. A wafer (W) is loaded on the upper surface of the loading area (18a). That is, the upper surface of the loading area (18a) functions as a loading surface on which the wafer (W) is loaded. The diameter of the loading area (18a) is approximately the same diameter as the wafer (W) or is slightly smaller than the diameter of the wafer (W). The outer periphery area (18b) is an area surrounding the loading area (18a) and extends in a roughly circular shape. In this embodiment, the upper surface of the outer periphery area (18b) is located lower than the upper surface of the loading area (18a).

[0029] As illustrated in FIG. 2, the electrostatic chuck (18) has an electrostatic adsorption electrode (E1) within the loading area (18a). The electrode (E1) is connected to a DC power source (22) through a switch (SW1) as described above.

[0030] Additionally, a plurality of heaters (HT) are provided within the loading area (18a) and also below the electrode (E1). In this embodiment, the loading area (18a) is divided into a plurality of divided areas, and a heater (HT) is provided in each divided area. For example, as shown in FIG. 2, a plurality of heaters (HT) are provided within a central circular area of ​​the loading area (18a) and in a plurality of concentric annular areas surrounding the circular area. In addition, in each of the plurality of annular areas, a plurality of heaters (HT) are arranged in a circumferential direction. Furthermore, the method of dividing the divided areas shown in FIG. 2 is an example and is not limited thereto. The loading area (18a) may be divided into more divided areas. For example, the loading area (18a) may be divided into divided areas that have a smaller angle width and a narrower diameter width closer to the outer periphery. The heater (HT) is individually connected to the heater power supply (HP) shown in FIG. 1 through wiring not shown provided on the outer periphery of the base (20). The heater power supply (HP) supplies individually adjusted power to each heater (HT) under control from the control unit (100). By doing so, the heat emitted by each heater (HT) is individually controlled, and the temperature of a plurality of divided areas within the loading area (18a) is individually adjusted.

[0031] A power detection unit (PD) is provided in the heater power supply (HP) to detect the power supplied to each heater (HT). Additionally, the power detection unit (PD) may be provided separately from the heater power supply (HP) in the wiring through which power flows 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 amount of power [W] as the power supplied to each heater (HT). The heater (HT) generates heat according to the amount of power. Therefore, the amount of power supplied to the heater (HT) represents the heater power. The power detection unit (PD) notifies the control unit (100) of power data representing the detected power supplied to each heater (HT).

[0032] Additionally, the loading platform (16) is provided with an unillustrated temperature sensor capable of detecting the temperature of the heater (HT) in each divided area of ​​the loading area (18a). The temperature sensor may be a component capable of measuring temperature independently of the heater (HT). Additionally, the temperature sensor may be placed in the wiring through which power flows to the heater (HT), and the temperature may be detected from the resistance value obtained by measuring the voltage and current applied to the heater (HT), utilizing the property that the electrical resistance of the main metal increases in proportion to the temperature rise. The sensor value detected by each temperature sensor is sent to the temperature measuring device (TD). The temperature measuring device (TD) measures the temperature of each divided area of ​​the loading area (18a) from each sensor value. The temperature measuring device (TD) notifies the control unit (100) of the temperature data indicating the temperature of each divided area of ​​the loading area (18a).

[0033] In addition, an electric gas, such as He gas, may be supplied between the upper surface of the electrostatic chuck (18) and the back surface of the wafer (W) by an electric gas supply mechanism and a gas supply line that are not shown.

[0034] [Configuration of the Control Unit]

[0035] Next, the control unit (100) will be described in detail. FIG. 3 is a block diagram illustrating an example of the schematic configuration of a control unit that controls a plasma processing device according to an embodiment. The control unit (100) is provided with an external interface (101), a process controller (102), a user interface (103), and a memory unit (104).

[0036] The external interface (101) is capable of communicating with each part of the plasma processing device (10) and inputs and outputs various data. For example, power data indicating the power supplied to each heater (HT) is input to the external interface (101) from the power detection unit (PD). Additionally, temperature data indicating the temperature of each divided area of ​​the loading area (18a) is input to the external interface (101) from the temperature measuring device (TD). Additionally, the external interface (101) outputs control data controlling the power supplied to each heater (HT) to the heater power supply (HP).

[0037] The process controller (102) is equipped with a CPU (Central Processing Unit) and controls each part of the plasma processing device (10).

[0038] The user interface (103) is composed of a keyboard for inputting commands to a process manager to manage the plasma processing device (10), a display for visualizing and displaying the operating status of the plasma processing device (10), etc.

[0039] In the memory unit (104), a control program (software) for realizing various processes executed in the plasma processing device (10) under the control of the process controller (102), a recipe in which processing condition data is stored, and parameters regarding the device or process for performing plasma processing are stored. Additionally, the recipe, such as the control program and processing condition data, may be used in a state where it is stored on a computer-readable computer recording medium (e.g., a hard disk, an optical disk such as a DVD, a flexible disk, a semiconductor memory, etc.).

[0040] The process controller (102) has internal memory for storing programs or data, reads a control program stored in a memory unit (104), and executes the processing of the read control program. The process controller (102) functions as various processing units as the control program operates. 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), a warning unit (102e), a change unit (102f), and a set temperature calculation unit (102g). Additionally, each function of the heater control unit (102a), the measurement unit (102b), the parameter calculation unit (102c), the output unit (102d), the warning unit (102e), the change unit (102f), and the set temperature calculation unit (102g) may be realized by being distributed among multiple controllers.

[0041] Here, the flow of energy affecting the temperature of the wafer (W) is described. FIG. 4 is a schematic diagram illustrating an example of the flow of energy affecting the temperature of the wafer. FIG. 4 shows a simplified loading platform (16) including a wafer (W) and an electrostatic chuck (ESC) (18). The example in FIG. 4 shows the flow of energy affecting the temperature of the wafer (W) for one divided area of ​​the loading area (18a) of the electrostatic chuck (18). The loading platform (16) has an electrostatic chuck (18) and a base (20). The electrostatic chuck (18) and the base (20) are bonded by an adhesive layer (19). A heater (HT) is provided inside the loading area (18a) of the electrostatic chuck (18). A refrigerant flow path (24) through which a refrigerant flows is formed inside the base (20).

[0042] The heater (HT) generates heat and its temperature rises according to the power supplied from the heater power source (HP). In FIG. 4, the power supplied to the heater (HT) is the heater power (P h It is represented as ). In the heater (HT), the heater power (P h The amount of heat generated per unit area (heat flux) (q) calculated by dividing the ) by the area (A) of the region where the heater (HT) of the electrostatic chuck (18) is provided. h ) is created.

[0043] In addition, when plasma treatment is performed, the temperature of the wafer (W) rises due to heat input from the plasma. In FIG. 4, the heat flux (q) from the plasma per unit area is calculated by dividing the amount of heat input from the plasma to the wafer (W) by the area of ​​the wafer (W). p It is represented as ).

[0044] It is known that the heat input from the plasma is primarily proportional to the product of the amount of plasma ions irradiated onto the wafer (W) and the bias potential for introducing the plasma ions into the wafer (W). The amount of plasma ions irradiated onto 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) from the first high-frequency power source (HFS) applied during the generation of the plasma. Additionally, the electron density of the plasma depends on the pressure inside the processing vessel (12). The bias potential for introducing the plasma ions into the wafer (W) is proportional to the power of the high-frequency power (LFS) from the second high-frequency power source (LFS) applied during the generation of the bias potential. Additionally, the bias potential for introducing the plasma ions into the wafer (W) depends on the pressure inside the processing vessel (12). In addition, when high-frequency power (LFS) is not applied to the loading platform (16), ions are introduced into the loading platform due to the potential difference between the plasma potential (plasma potential) generated when plasma is created and the loading platform (16).

[0045] In addition, heat input from the plasma includes heating by the luminescence of the plasma, irradiation of the wafer (W) by electrons or radicals in the plasma, and surface reactions on the wafer (W) by ions and radicals. These components also depend on the power of the alternating current or pressure. Heat input from the plasma also depends on other device parameters related to plasma generation, such as the distance between the loading platform (16) and the upper electrode (30) or the type of gas supplied to the processing space (S).

[0046] The heat transferred to the wafer (W) is transferred to the electrostatic chuck (18). Here, not all of the heat from the wafer (W) is transferred to the electrostatic chuck (18), but rather heat is transferred to the electrostatic chuck (18) depending on the degree of heat transfer hindrance, such as the degree of contact between the wafer (W) and the electrostatic chuck (18). The degree of heat transfer hindrance, i.e., thermal resistance, is inversely proportional to the cross-sectional area with respect to the direction of heat transfer. For this reason, in FIG. 4, the degree of heat transfer hindrance from the wafer (W) to the surface of the electrostatic chuck (18) is the thermal resistance (R) per unit area between the wafer (W) and the surface of the electrostatic chuck (18). th It is represented as ·A). Also, A is the area of ​​the region where the heater (HT) is provided. R th is the thermal resistance over the entire area where the heater (HT) is provided. In addition, in FIG. 4, the amount of heat input from the wafer (W) to the surface of the electrostatic chuck (18) is represented as the heat flux (q) per unit area from the wafer (W) to the surface of the electrostatic chuck (18). In addition, the thermal resistance (R) per unit area between the surface of the wafer (W) and the electrostatic chuck (18) th ·A) depends on the surface condition of the electrostatic chuck (18), the value of the DC voltage applied from the DC power source (22) to hold and support the wafer (W), and the pressure of the heating gas supplied between the upper surface of the electrostatic chuck (18) and the back surface of the wafer (W). In addition, the thermal resistance (R th ·A) also depends on other device parameters involved in thermal resistance or thermal conductivity.

[0047] The heat transferred to the surface of the electrostatic chuck (18) raises the temperature of the electrostatic chuck (18) and is also transferred to the heater (HT). In FIG. 4, the amount of heat input from the surface of the electrostatic chuck (18) to the heater (HT) is the heat flux (q) per unit area from the surface of the electrostatic chuck (18) to the heater (HT). c It is represented as ).

[0048] Meanwhile, the base (20) is cooled by the refrigerant flowing through the refrigerant path (24) to cool the contacting electrostatic chuck (18). In FIG. 4, the amount of heat dissipated from the back surface of the electrostatic chuck (18) to the base (20) through the adhesive layer (19) is the heat flux (q) per unit area from the back surface of the electrostatic chuck (18) to the base (20). sus It is represented as ). As a result, the heater (HT) is cooled by heat dissipation, and the temperature is lowered.

[0049] When the temperature of the heater (HT) is controlled to remain constant, the heater (HT) is in a state where the total sum of the heat input transferred to the heater (HT) and the heat generated by the heater (HT) is equal to the amount of heat dissipated from the heater (HT). For example, in the unignited state where the plasma is not ignited, the amount of heat generated by the heater (HT) is equal to the amount of heat dissipated from the heater (HT). FIG. 5a is a schematic diagram illustrating an example of the energy flow in the unignited state. In the example of FIG. 5a, a heat amount 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 remain constant, the heater power (P) from the heater power source (HP) to the heater (HT) h "100" of heat is generated by )

[0050] Meanwhile, for example, in an ignition state where plasma is ignited, the total amount of heat input to the heater (HT) and the total amount of heat generated from the heater (HT) are equal to the amount of heat dissipated from the heater (HT). FIG. 5b is a schematic diagram illustrating an example of the energy flow in an ignition state. Here, the ignition state includes a transient state and a steady state. The transient state is a state in which, for example, the amount of heat input to the wafer (W) or electrostatic chuck (18) is greater than the amount of heat dissipated, causing the temperature of the wafer (W) or electrostatic chuck (18) to tend to rise over time. The steady state is a state in which the amount of heat input and heat dissipated to the wafer (W) or electrostatic chuck (18) become equal, causing the temperature of the wafer (W) or electrostatic chuck (18) to stop tending to rise over time and the temperature to become approximately constant.

[0051] In the example of FIG. 5b, as well as through cooling from the base (20), a heat quantity of “100” is dissipated from the heater (HT). In the ignition state, the wafer (W) rises in temperature due to heat input from the plasma until it reaches a normal state. Heat is transferred from the wafer (W) to the heater (HT) through the electrostatic chuck (18). As described above, when the temperature of the heater (HT) is controlled to be constant, the heat quantity input to the heater (HT) and the heat quantity dissipated from the heater (HT) become equal. The amount of heat required to maintain the temperature of the heater (HT) constant decreases. Because of this, the power supplied to the heater (HT) decreases.

[0052] For example, in the example of FIG. 5b, which is set to a "transient state," a heat quantity of "80" is transferred from the plasma to the wafer (W). The heat transferred to the wafer (W) is transferred to the electrostatic chuck (18). Furthermore, if the temperature of the wafer (W) is not in a normal state, some 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). For this reason, of the heat quantity of "80" 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). The heat transferred to the surface of the electrostatic chuck (18) is transferred to the heater (HT). Furthermore, if the temperature of the electrostatic chuck (18) is not in a normal state, some 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 acting on the temperature rise of the electrostatic chuck (18) depends on the heat capacity of the electrostatic chuck (18). For this reason, out of the “60” amount of heat transferred to the surface of the electrostatic chuck (18), “40” amount of heat is transferred to the heater (HT). For this reason, when the temperature of the heater (HT) is controlled to be constant, the heater (HT) receives heater power (P) from the heater power supply (HP). h "60" of heat is generated by )

[0053] In addition, in FIG. 5b, in the example set to a "normal state," a heat quantity of "80" is transferred from the plasma to the wafer (W). The heat transferred to the wafer (W) is transferred to the electrostatic chuck (18). Also, when the temperature of the wafer (W) is in a normal state, the wafer (W) is in a state where the heat input and heat output are equal. Therefore, the heat quantity 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 transferred to the heater (HT). When the temperature of the electrostatic chuck (18) is in a normal state, the electrostatic chuck (18) is in a state where the heat input and heat output are equal. Therefore, the heat quantity 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 to be constant, the heater power (P) from the heater power supply (HP) to the heater (HT) h "20" of heat is generated by )

[0054] As shown in FIGS. 5a and 5b, the power supplied to the heater (HT) decreases in the ignition state compared to the non-ignition state. In addition, in the ignition state, the power supplied to the heater (HT) decreases until it reaches a normal state.

[0055] In addition, as illustrated in FIG. 5a and FIG. 5b, when the temperature of the heater (HT) is controlled to remain constant, regardless of whether it is in a "non-ignition state," "transient state," or "normal state," a heat quantity of "100" is dissipated from the heater (HT) by cooling from the base (20). That is, the heat flow rate (q) per unit area directed toward the refrigerant supplied from the heater (HT) to the refrigerant flow path (24) formed inside the base (20) susThe 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 be constant does not necessarily need to be installed directly on the heater (HT). For example, if the space between the heater (HT) and the refrigerant is the back surface of the electrostatic chuck (18), inside the adhesive layer (19), inside the base (20), etc., the temperature difference between the heater (HT) and the temperature sensor is always constant. By using the thermal conductivity and thermal resistance of the material between the heater (HT) and the temperature sensor, the temperature difference (ΔT) between the temperature sensor and the heater (HT) can be calculated, and the temperature difference (ΔT) can be output as the temperature of the heater (HT) by adding the temperature difference (ΔT) to the temperature value detected by the temperature sensor. This allows the actual temperature of the heater (HT) to be controlled to be constant.

[0056] FIG. 6 is a diagram illustrating an example of changes in the temperature of a wafer (W) and the power supplied to a heater (HT). FIG. 6 (A) shows a change in the temperature of the wafer (W). FIG. 6 (B) shows a change in the power supplied to the heater (HT). The example in FIG. 6 shows an example of the results obtained by controlling the temperature of the heater (HT) to be constant, igniting the plasma from an unignited state, and measuring the temperature of the wafer (W) and the power supplied to the heater (HT). The temperature of the wafer (W) was measured using a temperature measuring wafer such as an Etch Temp sold by KLA-Tencor.

[0057] Period T1 of FIG. 6 is an unignited state in which the plasma is not ignited. During period T1, the power supplied to the heater (HT) is constant. Period T2 of FIG. 6 is an ignited state in which the plasma is ignited, and it is a transient state. During period T2, the power supplied to the heater (HT) decreases. Also, during period T2, the temperature of the wafer (W) rises to a constant temperature. Period T3 of FIG. 6 is an ignited state in which the plasma is ignited. During period T3, the temperature of the wafer (W) is constant and it is in a steady state. When the electrostatic chuck (18) also reaches a steady state, the power supplied to the heater (HT) becomes approximately constant, and fluctuations with a downward trend stabilize. Period T4 of FIG. 6 is an unignited state in which the plasma is extinguished. During period T4, since there is no heat input from the plasma to the wafer (W), the temperature of the wafer (W) decreases, and the power supplied to the heater (HT) increases.

[0058] The tendency of the power supplied to the heater (HT) to decrease during the transient state shown in period T2 of Fig. 6 changes depending on the amount of heat input from the plasma to the wafer (W), the thermal resistance between the wafer (W) and the surface of the electrostatic chuck (18), etc.

[0059] FIG. 7 is a schematic diagram illustrating an example of the flow of energy in an ignition state. FIG. 7 is an example of a transient state. For example, in FIG. 7, in the example where "heat input: small, thermal resistance: small," "80" of 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 heat is transferred from the wafer (W) to the surface of the electrostatic chuck (18). Then, of the "60" of heat transferred to the surface of the electrostatic chuck (18), "40" of heat is transferred to the heater (HT). For example, when the temperature of the heater (HT) is controlled to remain constant, the heater power (P) from the heater power supply (HP) to the heater (HT) h "60" of heat is generated by )

[0060] In addition, in FIG. 7, in the example where "heat input: large, thermal resistance: small," "100" of heat is transferred from the plasma to the wafer (W). Of the "100" of heat transferred from the plasma to the wafer (W), "80" of heat is transferred from the wafer (W) to the surface of the electrostatic chuck (18). Then, of the "80" of heat transferred to the surface of the electrostatic chuck (18), "60" of heat is transferred to the heater (HT). For example, when the temperature of the heater (HT) is controlled to be constant, the heater power (P) from the heater power supply (HP) to the heater (HT) h "40" of heat is generated by )

[0061] In addition, in FIG. 7, in the example where "heat input: small, thermal resistance: large," "80" of heat is transferred from the plasma to the wafer (W). Of the "80" of heat transferred from the plasma to the wafer (W), "40" of heat 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" of heat is transferred to the heater (HT). For example, when the temperature of the heater (HT) is controlled to be constant, the heater power (P) from the heater power supply (HP) to the heater (HT) h "80" of heat is generated by )

[0062] In this way, when the temperature of the heater (HT) is controlled to be constant, the heater power (P hThe power supply to the heater (HT) in period T2, as shown in (B) of FIG. 6, changes depending on the amount of 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 decreasing trend of the power supply to the heater (HT) in period T2 changes depending on the amount of 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). For this reason, the graph of the power supply to the heater (HT) in period T2 can be modeled using the amount of 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) as parameters. That is, the change in the power supply to the heater (HT) in period T2 can be modeled by a calculation formula using the amount of 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) as parameters.

[0063] In this embodiment, the change in power supplied to the heater (HT) during period T2, as illustrated in FIG. 6 (B), is modeled as a formula per unit area. For example, let t be the elapsed time after igniting the plasma, and let the heater power (P) at elapsed time (t) be h ) to P h(t) Let be the amount of heat generated from the heater (HT) per unit area (q) when there is a heat flux from the plasma at elapsed time (t). h ) to q h(t) Let be the case where there is a heat flux from the plasma at elapsed time (t), and the amount of heat generated from the heater (HT) per unit area (q h(t) ) can be expressed as shown in the following equation (2). In addition, the amount of heat generated from the heater (HT) per unit area (q) in a steady state when the plasma is not ignited and there is no heat flux from the plasma. h_Off ) can be expressed as shown in the following equation (3). In addition, the thermal resistance per unit area (R) between the surface of the electrostatic chuck (18) and the heater thc ·A) can be expressed as shown in the following equation (4). Heat flux (q p) changes depending on whether plasma is generated or not. When plasma is generated, the heat flux per unit area (q) from the plasma to the wafer (W) is p ) heat flux (q p_on Let ). Heat flux per unit area (q) from plasma to wafer (W). p_on ), and thermal resistance per unit area (R) between the wafer (W) and the surface of the electrostatic chuck (18) th When a1, a2, a3, λ1, λ2, τ1, and τ2 are expressed as in the following equations (5) to (11) with ·A) as a parameter, the amount of heat generated from the heater (HT) per unit area (q) when there is a heat flux from the plasma h(t) ) can be expressed as shown in the following equation (1).

[0064]

[0065] Here,

[0066] P h(t) is the heater power [W] when there is heat flux from the plasma at elapsed time (t).

[0067] P h_Off is the heater power in the steady state [W / m²] when there is no heat flux from the plasma. 2 ]am.

[0068] q h(t) is the amount of heat generated from the heater (HT) per unit area [W / m²] when there is a heat flux from the plasma at elapsed time (t). 2 ]am.

[0069] q h_Off is the amount of heat generated from the heater (HT) per unit area in a steady state when there is no heat flux from the plasma [W / m² 2 ]am.

[0070] R th ·A is the heat flux per unit area from the plasma to the wafer (W) [W / m² 2 ]am.

[0071] 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] is.

[0072] A is the area of ​​the region where the heater is provided [m² 2 ]am.

[0073] ρ w is the density of the wafer (W) [kg / m³ 3 ]am.

[0074] C w is the heat capacity per unit area of ​​the wafer (W) [J / K·m² 2 ]am.

[0075] z w is the thickness [m] of the wafer (W).

[0076] ρ c is the density of the ceramic constituting the electrostatic chuck (18) [kg / m² 3 ]am.

[0077] C c is the heat capacity per unit area of ​​the ceramic constituting the electrostatic chuck (18) [J / K·m 2 ]am.

[0078] z c is the distance [m] from the surface of the electrostatic chuck (18) to the heater (HT).

[0079] κ c is the thermal conductivity [W / K·m] of the ceramic constituting the electrostatic chuck (18).

[0080] t is the elapsed time [sec] after igniting the plasma.

[0081] For a1 shown in Equation (5), 1 / a1 becomes a time constant indicating that the wafer (W) is difficult to heat up. Also, for a2 shown in Equation (6), 1 / a2 becomes a time constant indicating that heat from the electrostatic chuck (18) is difficult to penetrate and is difficult to heat up. Also, for a3 shown in Equation (7), 1 / a3 becomes a time constant indicating that heat from the electrostatic chuck (18) is difficult to penetrate and is difficult to heat up.

[0082] Area (A) of the heater (HT), density (ρ) of the wafer (W) w ), thermal capacity per unit area of ​​wafer (W) (C) w ), thickness (z) of the wafer (W) w ), the density (ρ) of the ceramic constituting the electrostatic chuck (18) c ), thermal capacity per unit area (C) of the ceramic constituting the electrostatic chuck (18) c ), 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 ) is determined respectively from the actual configuration of the wafer (W) or the plasma processing device (10). R thc ·A is the thermal conductivity (κ c ), distance(z c It is predetermined by Equation (4) from )

[0083] Heater power (P) when there is heat flux from the plasma at elapsed time (t) after igniting the plasma h(t) ), and heater power in the steady state when there is no heat flux from the plasma (P h_Off ) can be obtained by measurement using a plasma processing device (10). And, as shown in equations (2) and (3), the obtained heater power (P h(t) ) and heater power(P h_Off By dividing each of these by the area (A) of the heater (HT), the amount of heat generated from the heater (HT) per unit area (q) when there is heat flux from the plasma h(t) ), and the amount of heat generated from the heater (HT) per unit area (q) in a steady state when there is no heat flux from the plasma h_Off ) can be obtained.

[0084] And, heat flux per unit area (q) from the plasma to the wafer (W) p_on ), and thermal resistance per unit area (R) between the wafer (W) and the surface of the electrostatic chuck (18) th·A) can be obtained by using the measurement results and performing the fitting of equation (1).

[0085] In addition, the graph of the temperature of the wafer (W) during period T2 shown in (A) of FIG. 6 can also be modeled with parameters such as the amount of heat input from the plasma to the wafer (W) or the thermal resistance between the wafer (W) and the surface of the electrostatic chuck (18). In this embodiment, the change in the temperature of the wafer (W) during period T2 is modeled as a formula per unit area. For example, the heat flux per unit area (q) from the plasma to the wafer (W). p_on ), and thermal resistance per unit area (R) between the wafer (W) and the surface of the electrostatic chuck (18) th When using a1, a2, a3, λ1, λ2, τ1, and τ2 shown in equations (5) to (11) with ·A) as a parameter, the temperature (T) of the wafer (W) at elapsed time (t) W(t) )[℃] can be expressed as shown in the following equation (12).

[0086]

[0087] Here,

[0088] T W(t) is the temperature [°C] of the wafer (W) at elapsed time (t).

[0089] T h is the temperature [°C] of a constantly controlled heater (HT).

[0090] Temperature (T) of the heater (HT) h ) can be obtained from the conditions when the temperature of the wafer (W) is actually controlled to be constant.

[0091] By using the measurement results and fitting equation (1), the heat flux (q p_on ), and thermal resistance (R th If ·A) is obtained, the temperature (T) of the wafer (W) W ) can be calculated from Equation (12).

[0092] When the elapsed time (t) is sufficiently longer than the time constants (τ1, τ2) expressed by equations (10) and (11), that is, the temperature (T) of the wafer (W) after transitioning from the transient state of period T2 in FIG. 6 to the steady state of period T3. W The temperature (T) of the heater (HT) where ) becomes the target temperature h When calculating ), Equation (12) can be omitted as in Equation (13) below.

[0093]

[0094] For example, according to equation (13), the temperature of the heater (T h ), heat flux (q p_on ), thermal resistance (R th ·A, R thc ·A) From the temperature (T) of the wafer (W) W ) can be obtained.

[0095] However, the plasma processing device (10) is required to detect the state of the plasma during plasma processing in order to determine the state of the plasma processing. For example, the plasma processing device (10) is required to detect the density distribution of the plasma as the state of the plasma. In the plasma processing device (10), the amount of heat input from the plasma changes according to the density distribution of the plasma.

[0096] FIG. 8 is a schematic diagram illustrating an example of temperature changes in the non-ignition state and the transient state according to the plasma density distribution. FIG. 8 (A) to (D) shows the distribution of plasma density during plasma processing and the change in surface temperature of each divided area of ​​the loading area (16) in a time series. FIG. 8 (A) illustrates the non-ignition state. In the non-ignition state, plasma is not generated, and when the power supplied to each heater (HT) is controlled so that the temperature of each heater (HT) becomes constant, the temperature of each divided area of ​​the loading area (18a) also becomes constant. FIG. 8 (B) to (D) illustrates the transient state. In the area where the plasma density is high, the amount of heat input from the plasma to the loading area (18a) increases. In the area where the plasma density is low, the amount of heat input from the plasma to the loading area (18a) decreases. For example, if the density distribution of the generated plasma is high at the center of the loading area (18a) and low at the periphery, as shown in FIG. 8 (B) to (D), the heat input at the center of the loading area (18a) increases. Because of this, the surface temperature at the center of the loading area (18a) rises higher than at the periphery. When the power supplied to each heater (HT) is controlled to keep the temperature of each heater (HT) constant, the power supplied to the heater (HT) is reduced because the increase in the surface temperature of the loading area (18a) is reduced. Since the heater (HT) at the center of the loading area (18a) has a high heat input, the power supplied to the heater (HT) is significantly reduced compared to the heater (HT) at the periphery.

[0097] FIG. 9 is a schematic diagram illustrating an example of the flow of energy in the unignited state and the transient state. In addition, in the example of FIG. 9, the loading area (18a) is divided into three zones: a center near the center of the loading area (18a), a middle surrounding the center, and an edge surrounding the middle, which is near the edge of the loading area (18a). The density distribution of the plasma is assumed to be high at the center of the loading area (18a) and low at the periphery, similar to FIG. 8 (B) to (D).

[0098] In the non-ignition state illustrated in FIG. 9, 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 remain constant, the heater power (P) from the heater power supply (HP) to the heater (HT) h A heat quantity of “100” is generated by ). As a result, the heat quantity generated by the heater (HT) and the heat quantity radiated from the heater (HT) become equal.

[0099] Meanwhile, in the transient state illustrated in FIG. 9, since the density distribution of the plasma at the center of the loading area (18a) is higher than that of the surrounding area, the heat input at the center of the loading area (18a) is "large," the heat input at the middle is "medium," and the heat input at the edge is "small." For example, if the thermal resistance of the center, the middle, and the edge is made equal, at the center, "100" of heat is input from the plasma and "60" of heat is transferred to the heater (HT). At the middle, "80" of heat is input from the plasma and "40" of heat is transferred to the heater (HT). At the edge, "40" of heat is input from the plasma and "20" of heat is transferred to the heater (HT).

[0100] FIG. 10 is a diagram illustrating an example of the change in temperature of a wafer (W) and the power supplied to a heater (HT). FIG. 10 (A) shows the temperature change of the wafer (W) in the center, middle, and edge portions. FIG. 10 (B) shows the change in power supplied to the heater (HT) in the center, middle, and edge portions. As shown in FIG. 10 (B), the waveform of the power supplied changes according to the amount of heat input. Therefore, the amount of heat input for each zone can be obtained by measuring the power supplied to the heater (HT) in each zone during the non-ignition state and the transient state, and by using the measurement results for each zone to perform fitting of Equation (1). Then, the density distribution of the plasma can be obtained from the amount of heat input for each zone. That is, the plasma processing device (10) according to the embodiment can detect the state of the plasma without placing a sensor inside the processing vessel (12).

[0101] Return to Fig. 3. The heater control unit (102a) controls the temperature of each heater (HT). For example, the heater control unit (102a) controls the temperature of each heater (HT) by outputting control data that indicates the power supply to each heater (HT) to the heater power supply (HP) and controlling the power supply supplied from the heater power supply (HP) to each heater (HT).

[0102] When performing plasma processing, the heater control unit (102a) sets the target temperature for each heater (HT). For example, in the heater control unit (102a), for each divided area of ​​the loading area (18a), the target temperature of the target wafer (W) is set as the set temperature of the heater (HT) of the corresponding divided area. The target temperature is, for example, the temperature at which the precision of plasma etching for the wafer (W) is best.

[0103] The heater control unit (102a) controls the power supplied to each heater (HT) so that each heater (HT) reaches a set temperature during plasma processing. For example, the heater control unit (102a) compares the temperature of each divided area of ​​the loading area (18a) indicated by the temperature data input to the external interface (101) with the set temperature of the corresponding divided area for each divided area. Then, the heater control unit (102a) identifies a divided area with a temperature lower than the set temperature and a divided area with a temperature higher than the set temperature, respectively. The heater control unit (102a) outputs control data to the heater power supply (HP) to increase the power supplied to the divided area with a temperature lower than the set temperature and decrease the power supplied to the divided area with a temperature higher than the set temperature.

[0104] The measuring unit (102b) measures the power supplied to each heater (HT) using the power supplied to each heater (HT) indicated by the power data input to the external interface (101). For example, the measuring unit (102b) measures the power supplied to each heater (HT) in an unignited state where the plasma is not ignited by controlling the power supplied to each heater (HT) so that the temperature of each heater (HT) becomes constant by the heater control unit (102a). In addition, the measuring unit (102b) measures the power supplied to each heater (HT) in a transient state until the fluctuation of the tendency for the power supplied to each heater (HT) to decrease after the plasma is ignited stabilizes.

[0105] For example, the measuring unit (102b) measures the power supplied to each heater (HT) when the plasma is in a non-ignited state prior to the start of plasma processing, while the heater control unit (102a) controls the power supplied to each heater (HT) so that the temperature of each heater (HT) becomes a certain set temperature. Additionally, the measuring unit (102b) measures the power supplied to each heater (HT) in a transient state until the fluctuation of the tendency for the power supplied to each heater (HT) to decrease stabilizes after the plasma is ignited. The power supplied to each heater (HT) in a non-ignited state may be measured at least once in each heater (HT), or the average value may be taken from multiple measurements and used as the power supplied in the non-ignited state. The power supplied to each heater (HT) in a transient state may be measured at least twice. The timing for measuring the power supplied is preferably a timing when the tendency for the power supplied to decrease is significant. In addition, when the number of measurements is small, it is desirable that the measurement timing be spaced apart for a predetermined period. 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 the plasma treatment period. By doing so, the power supplied to each heater (HT) in a transient state is measured multiple times.

[0106] The measurement unit (102b) measures the power supplied to each heater (HT) in the non-ignition state and transient state during a predetermined cycle. For example, the measurement unit (102b) measures the power supplied to each heater (HT) in the non-ignition state and transient state each time when a wafer (W) is exchanged and the exchanged wafer (W) is loaded onto a loading platform (16) to perform plasma processing. Additionally, for example, the parameter calculation unit (102c) may measure the power supplied to each heater (HT) in the non-ignition state and transient state for each plasma processing.

[0107] The parameter calculation unit (102c) calculates the heat input and thermal resistance using a calculation model that calculates the supply power in a transient state, using the heat input from the plasma and the thermal resistance between the wafer (W) and the heater (HT) as parameters for each heater (HT). For example, the parameter calculation unit (102c) calculates the heat input and thermal resistance by performing fitting on the calculation model using the supply power in the non-ignition state and transient state measured by the measurement unit (102b).

[0108] For example, the parameter calculation unit (102c) calculates the heater power (P) in the non-ignition state for each heater (HT) at each elapsed time (t). h_Off ) is calculated. In addition, the parameter calculation unit (102c) calculates the transient state heater power (P) for each heater (HT) at each elapsed time (t). h(t) ) is calculated. And, the parameter calculation unit (102c) calculates the calculated heater power (P h(t) ) and heater power(P h_Off By dividing each of these by the area of ​​each heater (HT), the amount of heat generated from the heater (HT) per unit area in the unignited state (q) per elapsed time (t) h_Off ) and the amount of heat generated from the heater (HT) per unit area in the transient state according to elapsed time (t) (q h(t) ) obtains.

[0109] The parameter calculation unit (102c) uses the above equations (1) to (11) as a calculation model, and for each heater (HT), the amount of heat generated from the heater (HT) per unit area per elapsed time (t) (q h(t) ), and heat generation amount from the heater (HT) per unit area (q h_Off By performing a fitting of ), the heat flux (q) at which the error is minimized is obtained. p_on ), and thermal resistance (R th Calculate ·A).

[0110] The parameter calculation unit (102c) uses the supply power of the measured non-ignition state and transient state in a predetermined cycle to calculate the heat flux (q p_on ), and thermal resistance (R th·A) is calculated. For example, the parameter calculation unit (102c) calculates the heat flux (q) using the supply power in the non-ignition state and transient state measured while the wafer (W) is loaded on the loading platform (16) whenever the wafer (W) is exchanged. p_on ), and thermal resistance (R th ·A) is calculated. In addition, for example, the parameter calculation unit (102c) uses the supply power in the non-ignition state and transient state for each plasma treatment to calculate the heat flux (q p_on ), and thermal resistance (R th ·A) may be calculated.

[0111] The output unit (102d) controls the output of various information. For example, the output unit (102d) controls the heat flux (q) calculated by the parameter calculation unit (102c) in a predetermined cycle. p_on It outputs information based on ). For example, the output unit (102d) outputs the heat flux (q) per heater (HT) calculated by the parameter calculation unit (102c). p_on Based on ), information indicating the density distribution of the plasma is output to the user interface (103). For example, the output unit (102d) outputs information indicating the density distribution of the plasma when plasma processing is performed on the wafer (W) whenever the wafer (W) is exchanged to the user interface (103). Additionally, the output unit (102d) may output the information indicating the density distribution of the plasma as data to an external device.

[0112] FIG. 11a is a diagram illustrating an example of the output of information representing the density distribution of a plasma. In the example of FIG. 11a, for each divided area of ​​the loading area (18a) provided with a heater (HT), the heat flux (q) of the said divided area p_on It displays ) as a pattern.

[0113] FIG. 11b is a diagram illustrating an example of the output of information representing the density distribution of a plasma. In the example of FIG. 11b, the heat flux (q) of the center, middle, and edge regions is p_on ) is located in the city.

[0114] By doing so, the process manager or the manager of the plasma processing device (10) can determine the state of the plasma.

[0115] However, there may be cases where an abnormality occurs in the state of the plasma in the plasma processing device (10). For example, in the plasma processing device (10), the characteristics inside the processing vessel (12) may change due to significant wear of the electrostatic chuck (18) or the attachment of deposition, and the state of the plasma may become an abnormal state that is not suitable for plasma processing. In addition, there may be cases where an abnormal wafer (W) is introduced into the plasma processing device (10).

[0116] Therefore, the warning unit (102e) issues a warning based on the amount of heat input or the change in the amount of heat input calculated by the parameter calculation unit (102c) in a predetermined cycle. For example, the warning unit (102e) issues a warning based on the heat flux (q) calculated by the parameter calculation unit (102c) in a predetermined cycle. p_on If ) is outside the predetermined allowable range, a warning is issued. In addition, the warning unit (102e) is a heat flux (q) calculated by the parameter calculation unit (102c) in a predetermined cycle. p_on If the value changes by more than a predetermined allowable value, a warning is issued. The warning can be any method that can notify a process manager or a manager of the plasma processing device (10) of the abnormality. For example, the warning unit (102e) displays a message notifying the abnormality to the user interface (103).

[0117] Accordingly, the plasma processing device (10) according to the present embodiment can notify of the occurrence of an abnormality when the state of the plasma becomes abnormal due to characteristics within the processing container (12) or the introduction of an abnormal wafer (W).

[0118] The changing unit (102f) changes the control parameters of the plasma treatment so that the plasma treatment on the wafer (W) is equalized based on information indicating the density distribution of the plasma.

[0119] Here, plasma etching involves factors of surface adsorption of radicals, escape by thermal energy, and escape by ion collision. Fig. 12 is a schematic diagram illustrating plasma etching. The example in Fig. 12 models the state of plasma etching the surface of an organic film with O2 gas. The surface of the organic film is etched by the synergistic action of adsorption of O radicals, escape by thermal energy, and escape by ion collision.

[0120] The etching rate (E / R) of plasma etching can be expressed by the following equation (14).

[0121]

[0122] Here,

[0123] n c is a value representing the material of the etched film.

[0124] Γ radical Silver is the supply amount of radicals.

[0125] s is the probability of adsorption to the surface.

[0126] K d is the thermal reaction rate.

[0127] Γ ion It is the amount of ion incident.

[0128] E i is ion energy.

[0129] k is the reaction probability of ionic desorption.

[0130] "K" of equation (14) d The 」 part indicates the escape due to thermal energy. 「kE i ·Γ ion The 」 part indicates detachment due to ion collision. 「s·Γ radical The 」 part indicates the surface adsorption of radicals.

[0131] The concentration distribution of the plasma affects the escape due to ion collisions, and the “kE” of Equation (14 i ·Γ ion The 」 portion changes depending on the plasma concentration. The etching rate is, "K d The 」 part or 「s·Γ radical It also changes depending on the 」 part. For this reason, corresponding to the plasma density distribution, "K d The 」 part or 「s·Γ radical By changing the 」 portion, the etching rate can be equalized. The changing portion (102f) equalizes the plasma treatment on the wafer (W) based on information representing the density distribution of the plasma, so that the "K d The 」 part or 「s·Γ radical Change the control parameters of the plasma treatment that affect the 」 part.

[0132] For example, "K d The 」 portion changes, for example, depending on the temperature of the wafer (W). Also, 「s·Γ radical The 」 part changes depending on the concentration of the gas that becomes plasma.

[0133] The changing unit (102f) changes the target temperature of the wafer (W) for each divided area of ​​the loading area (18a) based on information indicating the density distribution of the plasma. For example, the changing unit (102f) changes the target temperature so that the escape due to thermal energy is reduced for a divided area with a high plasma density. For example, the changing unit (102f) changes the target temperature to a lower value. Additionally, the changing unit (102f) changes the target temperature so that the escape due to thermal energy is increased for a divided area with a low plasma density. For example, the changing unit (102f) changes the target temperature to a higher value. Additionally, if the upper electrode (30) is configured to allow the concentration of the gas discharged to be changed for each divided area that divides the lower surface, the changing unit (102f) may change the concentration of the gas discharged for each divided area of ​​the upper electrode (30) based on information indicating the density distribution of the plasma. For example, the changing unit (102f) changes the gas concentration in the divided region with high plasma density to a low level. Additionally, the changing unit (102f) changes the gas concentration in the divided region with low plasma density to a high level. The changing unit (102f) may simultaneously change the target temperature of the wafer (W) for each divided region and change the concentration of the gas discharged for each divided region of the upper electrode (30).

[0134] The set temperature calculation unit (102g) calculates the set temperature of the heater (HT) at which the wafer (W) reaches the target temperature, using the calculated heat input and thermal resistance for each heater (HT). For example, the set temperature calculation unit (102g) calculates the heat flux (q) calculated for each heater (HT). p_on ), and thermal resistance (R th ·A) is substituted into equations (5), (6), and (12). Then, the set temperature calculation unit (102g), for each heater (HT), uses a1, a2, a3, λ1, λ2, τ1, and τ2 shown in equations (5) to (11) to calculate the temperature (T) of the wafer (W) from equation (12). WThe temperature (T) of the heater (HT) where ) becomes the target temperature h ) calculates. For example, the set temperature calculation unit (102g) sets the elapsed time (t) to a predetermined value large enough to be considered a normal state, and calculates the temperature (T) of the wafer (W). W The temperature (T) of the heater (HT) where ) becomes the target temperature h Calculates the temperature (T) of the heater (HT) calculated. h ) is the temperature of the heater (HT) at which the temperature of the wafer (W) reaches the target temperature. Also, the temperature of the heater (HT) at which the temperature of the wafer (W) reaches the target temperature (T h ) can be obtained from Equation (13).

[0135] In addition, the set temperature calculation unit (102g) calculates the current temperature (T) of the heater (HT) as follows from equation (12). h Temperature (T) of the wafer (W) at ) W ) may be calculated. For example, the set temperature calculation unit (102g) calculates the current temperature (T of the heater (HT)). h In ), the temperature (T) of the wafer (W) when the elapsed time (t) is set to a predetermined value large enough to be considered a steady state. W ) calculates. Next, the set temperature calculation unit (102g) calculates the calculated temperature (T W The difference between ) and the target temperature (ΔT W ) calculates. And, the set temperature calculation unit (102g) calculates the current temperature (T) of the heater (HT). h Difference (ΔT) at ) W The temperature obtained by subtracting ) may be calculated as the temperature of the heater (HT) where the temperature of the wafer (W) becomes the target temperature.

[0136] The set temperature calculation unit (102g) modifies the set temperature of each heater (HT) of the heater control unit (102a) to the temperature of the heater (HT) at which the temperature of the wafer (W) becomes the target temperature.

[0137] The set temperature calculation unit (102g) calculates the temperature of the heater (HT) at which the temperature of the wafer (W) becomes the target temperature in a predetermined cycle and modifies the set temperature of each heater (HT). For example, the set temperature calculation unit (102g) calculates the temperature of the heater (HT) at which the temperature of the wafer (W) becomes the target temperature whenever the wafer (W) is exchanged and modifies the set temperature of each heater (HT). Additionally, for example, the set temperature calculation unit (102g) may calculate the temperature of the heater (HT) at which the temperature of the wafer (W) becomes the target temperature for each plasma process and modify the set temperature of each heater (HT).

[0138] Accordingly, the plasma processing device (10) according to the present embodiment can control the temperature of the wafer (W) during plasma processing to a target temperature with high precision.

[0139] [Flow of Control]

[0140] Next, a method for detecting a plasma state using a plasma processing device (10) according to the present embodiment will be described. FIG. 13 is a flowchart showing an example of the flow of processing for detecting a plasma state and controlling a plasma state according to the embodiment. This processing is performed at a predetermined timing, for example, at the timing when starting plasma processing.

[0141] The heater control unit (102a) controls the power supplied to each heater (HT) so that each heater (HT) reaches a set temperature (step S10).

[0142] The measuring unit (102b) measures the power supplied to each heater (HT) in the non-ignition state and transient state while the heater control unit (102a) controls the power supplied to each heater (HT) so that the temperature of each heater (HT) becomes a certain set temperature (step S11).

[0143] The parameter calculation unit (102c) calculates the heat input and thermal resistance by performing fitting for each heater (HT) using the amount of heat generated from the heater (HT) per unit area, which is obtained by dividing the measured supply power in the non-ignition state and transient state by the area of ​​the heater (HT) for the calculation model (step S12). For example, the parameter calculation unit (102c) uses the above equations (1) to (11) as a calculation model to calculate the amount of heat generated from the heater (HT) per unit area (q) for each heater (HT) per elapsed time (t). h(t) ), and heat generation amount from the heater (HT) per unit area (q h_Off By performing a fitting of ), the heat flux (q) at which the error is minimized is obtained. p_on ) and thermal resistance (R th Calculate ·A).

[0144] The output unit (102d) outputs information based on the heat input amount calculated by the parameter calculation unit (102c) (step S13). For example, the output unit (102d) outputs the heat flux (q per heater (HT)) calculated by the parameter calculation unit (102c). p_on Based on ), information representing the density distribution of the plasma is output to the user interface (103).

[0145] The changing unit (102f) changes the control parameters of the plasma treatment so that the plasma treatment for the wafer (W) is equalized based on information indicating the density distribution of the plasma (step S14). For example, the changing unit (102f) changes the target temperature of the wafer (W) for each divided area of ​​the loading area (18a) based on information indicating the density distribution of the plasma.

[0146] The set temperature calculation unit (102g) calculates the set temperature of the heater (HT) at which the wafer (W) reaches the target temperature using the calculated heat input and thermal resistance for each heater (HT) (step S15). For example, the set temperature calculation unit (102g) calculates the heat flux (q) calculated for each heater (HT). p_on ), and thermal resistance (Rth ·A) is substituted into equations (5), (6), and (12). Then, the set temperature calculation unit (102g) uses a1, a2, a3, λ1, λ2, τ1, and τ2 shown in equations (5) to (11) to calculate the temperature (T) of the wafer (W) from equation (12). W The temperature (T) of the heater (HT) where ) becomes the target temperature h ) is calculated. In addition, the temperature (T) of the heater (HT) at which the temperature of the wafer (W) becomes the target temperature is calculated. h ) can be obtained from Equation (13).

[0147] The set temperature calculation unit (102g) modifies the set temperature of each heater (HT) of the heater control unit (102a) to the set temperature of the heater (HT) at which the temperature of the wafer (W) becomes the target temperature (step S16), and terminates the processing.

[0148] As such, the plasma processing device (10) according to the present embodiment has a loading platform (16), a heater control unit (102a), a measurement unit (102b), a parameter calculation unit (102c), and an output unit (102d). The loading platform (16) is provided with a heater (HT) capable of adjusting the temperature of the loading surface on which a wafer (W) is loaded. The heater control unit (102a) controls the power supplied to the heater (HT) so that the heater (HT) reaches a set temperature. The measurement unit (102b) controls the power supplied to the heater (HT) so that the temperature of the heater (HT) becomes constant by the heater control unit (102a), and measures the power supplied in a non-ignition state where the plasma is not ignited, and in a transient state where the power supplied to the heater (HT) decreases after the plasma is ignited. The parameter calculation unit (102c) calculates the heat input amount by performing fitting on a calculation model that includes the heat input amount from the plasma as a parameter and calculates the supply power in the transient state using the supply power in the non-ignition state and transient state measured by the measurement unit (102b). The output unit (102d) outputs information based on the heat input amount calculated by the parameter calculation unit (102c). By doing so, the plasma processing device (10) can detect the state of the plasma without placing a sensor inside the processing vessel (12).

[0149] In addition, the plasma processing device (10) according to the present embodiment has a heater (HT) individually provided for each area in which the loading surface of the loading platform (16) is divided. The heater control unit (102a) controls the power supply for each heater (HT) so that the heater (HT) provided for each area reaches a set temperature for each area. The measurement unit (102b) controls the power supply so that the temperature of each heater (HT) becomes constant by the heater control unit (102a), and measures the power supply for each heater (HT) in the non-ignition state and the transient state. The parameter calculation unit (102c) performs fitting on the calculation model for each heater (HT) using the power supply for the non-ignition state and the transient state measured by the measurement unit (102b), and calculates the amount of heat input for each heater (HT). The output unit (102d) outputs information indicating the density distribution of the plasma based on the heat input amount per heater (HT) calculated by the parameter calculation unit (102c). Accordingly, the plasma processing device (10) can provide information indicating the density distribution of the plasma during plasma processing without placing a sensor inside the processing vessel (12).

[0150] Additionally, the plasma processing device (10) according to the present embodiment further has a changing part (102f). The changing part (102f) changes the control parameters of the plasma processing so that the plasma processing on the wafer (W) is equalized based on the density distribution of the plasma. By doing so, the plasma processing device (10) can equalize the plasma processing on the wafer (W).

[0151] Additionally, the plasma processing device (10) according to the present embodiment further has a warning unit (102e). The warning unit (102e) provides a warning based on information output by the output unit (102d) or a change in said information. Accordingly, the plasma processing device (10) can provide a warning when an abnormality occurs in the state of the plasma.

[0152] Although embodiments have been described above, the embodiments disclosed herein should be considered illustrative in all respects and not restrictive. In practice, the above-described embodiments may be implemented in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and intent of the claims.

[0153] For example, in the above embodiment, the case where plasma treatment is performed on a semiconductor wafer as the workpiece was described as an example, but it is not limited thereto. The workpiece may be any material that is affected by temperature in the progress of the plasma treatment. For example, the workpiece may be a glass substrate, etc.

[0154] In addition, in the above embodiment, plasma etching was described as an example of plasma treatment, but it is not limited to this. Plasma treatment can be any treatment using plasma. Examples of plasma treatments include chemical vapor deposition (CVD), atomic layer deposition (ALD), ashing, plasma doping, plasma annealing, etc.

[0155] Additionally, in the above embodiment, the plasma processing device (10) has a first high-frequency power supply (HFS) for plasma generation and a second high-frequency power supply (LFS) for bias power connected to the base (20), but is not limited thereto. The first high-frequency power supply (HFS) for plasma generation may be connected to the upper electrode (30) through a matching unit (MU).

[0156] In addition, in the above embodiment, the plasma processing device (10) was a capacitively coupled parallel plate plasma processing device, but it can be adopted as any plasma processing device. For example, the plasma processing device (10) may be any type of plasma processing device, such as an inductively coupled plasma processing device or a plasma processing device that excites gas by surface waves such as microwaves.

[0157] In addition, in the above embodiment, the changing unit (102f) was described as an example of changing the target temperature of the wafer (W) for each divided area of ​​the loading area (18a) based on information indicating the plasma density distribution, but it is not limited to this. For example, in the case where the distribution of plasma density in plasma generation is configured to be changed for each divided area or approximated divided area of ​​the lower surface of the upper electrode (30), the changing unit (102f) may change the plasma density for each divided area of ​​plasma generation based on information indicating the plasma density distribution. Furthermore, as an example of a configuration in which the distribution of plasma density is changed for each divided area, in the case of a capacitively coupled parallel plate plasma processing device, the upper electrode (30) is divided for each divided area, and a plurality of first high-frequency power sources (HFS) capable of generating different high-frequency power for each divided area of ​​the upper electrode may be connected. In addition, in the case of an inductively coupled plasma processing device, a plasma generating antenna is divided into divided regions, and a configuration can be provided in which multiple first high-frequency power sources (HFS) capable of generating different high-frequency power for each region of the divided antenna are connected.

[0158] In addition, in the above embodiment, although the case in which a heater (HT) is provided in each divided area of ​​the loading area (18a) of the loading platform (16) has been described as an example, it is not limited to this. A single heater (HT) may be provided in the entire loading area (18a) of the loading platform (16), and the power supplied to the heater (HT) in the non-ignition state and transient state may be measured, and the heat input amount may be calculated by fitting the measurement results to a calculation model. Since the calculated heat input amount is the heat input amount of the entire plasma, the state of the entire plasma can be detected from the calculated heat input amount.

[0159] In addition, in the above embodiment, as shown in FIG. 2, the loading area (18a) of the loading platform (16) is divided into a central circular area and a plurality of concentric annular areas surrounding the circular area, but this is not limited thereto. FIG. 14 is a plan view illustrating an example of the division of the loading surface of the loading platform according to the embodiment. For example, as shown in FIG. 14, the loading area (18a) of the loading platform (16) may be divided into a grid shape, and a heater (HT) may be provided in each divided area. By doing so, the amount of heat input can be detected for each grid-shaped divided area, and the density distribution of the plasma can be obtained in more detail. Explanation of the symbols

[0160] 10: Plasma treatment device 16: Loading rack 18: Power outage check 18a: Loading area 20: Bass 100: Control unit 102: Process Controller 102a: Heater control unit 102b: Measurement section 102c: Parameter calculation unit 102d: Output section 102e: Warning section 102f: Modification section 102g: Set temperature calculation unit HP: Heater Power HT: Heater PD: Power detection unit TD: Temperature sensor W: Wafer

Claims

Claim 1 A plasma processing apparatus having a loading platform equipped with a heater capable of adjusting the temperature of a loading surface on which a workpiece to be treated for plasma processing is loaded, a heater control unit that controls the power supplied to the heater so that the heater reaches a set temperature, a measuring unit that measures the power supplied to the heater in a non-ignited state where the plasma is not ignited and in an ignited state after plasma ignition by controlling the power supplied to the heater so that the temperature of the heater becomes constant by the heater control unit, a parameter calculation unit that calculates the amount of heat input from the plasma using the power supplied in the non-ignited state and the ignited state measured by the measuring unit, and an output unit that outputs information based on the amount of heat input calculated by the parameter calculation unit. Claim 2 A plasma processing apparatus according to claim 1, wherein the loading platform is provided with a heater individually for each area in which the loading surface is divided, the heater control unit controls the supply power for each heater so that the heater provided for each area reaches a set temperature for each area, the measuring unit controls the supply power so that the temperature of each heater becomes constant by the heater control unit, and measures the supply power for each heater in the non-ignition state and the ignition state, the parameter calculation unit calculates the heat input amount for each heater using the supply power for the non-ignition state and the ignition state measured by the measuring unit for each heater, and the output unit outputs information based on the heat input amount for each heater calculated by the parameter calculation unit. Claim 3 A plasma treatment apparatus according to claim 1 or 2, wherein the information is information representing the density distribution of the plasma, and further comprising a modification unit that changes control parameters of the plasma treatment to equalize the plasma treatment for the workpiece based on the density distribution of the plasma. Claim 4 A plasma processing apparatus characterized by further comprising, in claim 1 or 2, a warning unit that provides a warning based on information output by the output unit or a change in said information. Claim 5 A plasma processing apparatus according to claim 1, wherein the measuring unit measures the power supplied to the heater in the non-ignition state and the ignition state in a predetermined cycle, and the parameter calculation unit calculates the heat input amount using the power supplied in the non-ignition state and the ignition state measured by the measuring unit for each cycle. Claim 6 A plasma processing apparatus according to claim 1, wherein the measuring unit measures the power supplied to the heater in the non-ignition state and the ignition state whenever plasma processing is performed, and the parameter calculation unit calculates the heat input amount using the power supplied in the non-ignition state and the ignition state measured by the measuring unit whenever plasma processing is performed. Claim 7 A plasma processing device according to claim 1, wherein the ignition state after plasma ignition is a transient state in which the power supplied to the heater decreases after igniting the plasma. Claim 8 In claim 7, the plasma processing device wherein the measuring unit measures the power supplied to the heater two or more times during the transient state. Claim 9 In paragraph 3, the above-mentioned changing unit changes the target temperature of the wafer in each divided region of the loading area based on information indicating the plasma density distribution, a plasma processing device. Claim 10 In paragraph 3, the above-mentioned changing part changes the concentration of the discharged gas for each divided region of the upper electrode based on information indicating the plasma density distribution, in a plasma treatment device. Claim 11 In paragraph 2, the above-mentioned loading platform is a plasma processing device in which a temperature sensor capable of detecting the temperature of a heater is provided in each area where the loading surface is divided. Claim 12 In paragraph 11, the temperature sensor is a plasma processing device installed in a heater. Claim 13 In claim 11, the above temperature sensor is a plasma treatment device provided between a heater and a refrigerant. Claim 14 In paragraph 2, the loading platform is a plasma processing device in which the loading surface is divided into a plurality of regions in the perimeter direction. Claim 15 In claim 14, the above plurality of regions is a plasma processing device in which the width in the diameter direction is narrower as the loading surface is closer to the outer circumference. Claim 16 A plasma state detection method characterized by a computer executing a process of controlling the power supplied to a heater so that the temperature of the heater on a loading platform, which is equipped with a heater capable of adjusting the temperature of the loading surface on which a workpiece to be treated for plasma treatment is loaded, becomes constant, measuring the power supplied in a non-ignited state where the plasma is not ignited and in an ignited state after the plasma is ignited, calculating the amount of heat input from the plasma using the measured power supplied in the non-ignited state and the ignited state, and outputting information based on the calculated amount of heat input. Claim 17 A plasma state detection program stored in a medium for executing a process on a computer to control the power supplied to a heater so that the temperature of the heater on a loading platform, which is equipped with a heater capable of adjusting the temperature of the loading surface on which a workpiece subject to plasma treatment is loaded, becomes constant, to measure the power supplied in a non-ignited state where the plasma is not ignited and in an ignited state after plasma ignition, to calculate the amount of heat input from the plasma using the measured power supplied in the non-ignited state and the ignited state, and to output information based on the calculated amount of heat input.

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