High-speed automatic radio frequency control method and apparatus

Abstract

A high-speed automatic radio frequency control device and method are disclosed. A radio frequency control method according to one embodiment can include a step of calculating, on a complex reflection coefficient plane, an impedance locus circle of a load to which a radio frequency signal is provided, and a step of tuning a frequency of the radio frequency signal to a frequency corresponding to a target impedance measured at the load using the impedance locus circle.

Description

Technical Field

[0001] This invention discloses a high-speed automatic radio frequency control device and method for plasma processing apparatus. Background Technology

[0002] In semiconductor processing, which involves etching, depositing, and cleaning pure semiconductor wafers, plasma processing equipment is used as a core component.

[0003] Typically, a plasma processing device consists of a plasma reaction chamber, an RF generator that generates radio frequency (RF) power, and an impedance matcher that matches the output impedance of the RF generator to the impedance of the plasma reaction chamber in order to provide maximum power and thus minimize the power loss of the plasma reaction chamber.

[0004] However, in plasma processing equipment, the impedance within the plasma reaction chamber, which serves as the load for providing radio frequency signals, undergoes drastic changes, resulting in poor impedance matching when using an impedance matching device.

[0005] Therefore, as an alternative, impedance matching technology by controlling the frequency of radio frequency signals is under research and development, but no specific solution has been proposed yet.

[0006] Therefore, it is necessary to propose a frequency control technique for impedance matching. Summary of the Invention

[0007] (The problem that the invention aims to solve)

[0008] Some embodiments provide a high-speed automatic radio frequency control device and method for impedance matching to adapt to environments where impedance changes drastically in plasma reaction chambers.

[0009] However, the technical problem that this invention aims to solve is not limited to the above-mentioned problem, and various extensions can be made without departing from the technical concept and scope of this invention.

[0010] (The measures taken to solve the problem)

[0011] According to one embodiment, a radio frequency control method may include the step of calculating the impedance trajectory circle of a load that provides a radio frequency signal to a complex reflection coefficient plane;

[0012] The step of using the impedance trajectory circle to tune the frequency of the radio frequency signal to a frequency corresponding to the target impedance measured at the load.

[0013] According to one aspect, the calculation step may be a step of calculating the impedance trajectory circle by measuring the impedance at the load caused by the frequency variation of the radio frequency signal.

[0014] According to another aspect, the calculation step may be a step of calculating the impedance trajectory circle connecting three or more points on the complex reflection coefficient plane by changing the frequency of the radio frequency signal to at least three or more values ​​and measuring the impedance at the load respectively, the three or more points corresponding to the impedance at the load measured respectively when the frequency of the radio frequency signal is changed to at least three or more values.

[0015] According to another aspect, the tuning step may include: determining the angle between a line passing through a target point on the complex reflection coefficient plane corresponding to the target impedance and the center point of the impedance trajectory circle, and a reference vector passing through the origin of the complex reflection coefficient plane and the center point of the impedance trajectory circle; and calculating the frequency corresponding to the target impedance based on the determined angle.

[0016] According to another aspect, the calculation steps may include: generating a frequency step for calculating the frequency corresponding to the target impedance based on the determined angle; and adding the generated frequency step to the frequency of the radio frequency signal to tune the frequency of the radio frequency signal to the frequency corresponding to the target impedance.

[0017] According to one embodiment, a radio frequency control device may include: a calculation unit for calculating, on a complex reflection coefficient plane, an impedance trajectory circle of a load to which a radio frequency signal is supplied; and a tuning unit for using the impedance trajectory circle to tune the frequency of the radio frequency signal to a frequency corresponding to a target impedance measured at the load.

[0018] According to one aspect, the calculation unit can calculate the impedance trajectory circle by measuring the impedance generated as the frequency of the radio frequency signal in the load changes.

[0019] According to another aspect, the calculation unit calculates the impedance trajectory circle connecting three or more points on the complex reflection coefficient plane that correspond to the measured load impedances by changing the frequency of the radio frequency signal to at least three values ​​and measuring the impedance in the load respectively.

[0020] According to another aspect, the tuning unit determines the angle between a straight line passing through the target point on the complex reflection coefficient plane corresponding to the target impedance and the center point of the impedance trajectory circle, and a reference vector passing through the origin of the complex reflection coefficient plane and the center point of the impedance trajectory circle, and is able to calculate the frequency corresponding to the target impedance based on the determined angle.

[0021] According to another aspect, the tuning unit generates a frequency step size based on the determined angle for calculating the frequency corresponding to the target impedance, and adds the generated frequency step size to the frequency of the radio frequency signal, thereby tuning the frequency of the radio frequency signal to the frequency corresponding to the target impedance.

[0022] (The effect of the invention)

[0023] Some embodiments may provide a high-speed automatic radio frequency control device and method for impedance matching to adapt to environments where impedance changes drastically in plasma reaction chambers.

[0024] However, the beneficial effects of the present invention are not limited to the above-described effects, and various extensions can be made without departing from the technical concept and scope of the present invention. Attached Figure Description

[0025] Figure 1 This is a block diagram illustrating a plasma processing apparatus according to one embodiment.

[0026] Figure 2 This is a block diagram illustrating a radio frequency control device according to one embodiment.

[0027] Figure 3 This is a flowchart illustrating a radio frequency control method according to one embodiment.

[0028] Figures 4 to 7 This is a diagram illustrating the complex reflection coefficient plane to explain a radio frequency control method according to one embodiment. Detailed Implementation

[0029] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can readily implement the invention. Since the description of the invention is merely for illustrating structural or functional embodiments, the scope of the claims should not be construed as being limited to the embodiments described herein.

[0030] The high-speed automatic radio frequency control device and method will be described below with reference to the accompanying drawings.

[0031] Figure 1 This is a block diagram illustrating a plasma processing apparatus according to one embodiment.

[0032] Reference Figure 1 According to one embodiment, the plasma processing apparatus (100) may include a radio frequency power generator (110), an impedance matching device (120), and a plasma reaction chamber (130).

[0033] The radio frequency power generator (110) may include an oscillator (not shown), a power amplifier (not shown), and a filter (not shown) to generate a radio frequency signal (RF signal) with a specific frequency. Additionally, if desired, it may include a sensor (not shown) for measuring the impedance generated in the plasma reaction chamber (130) due to the supply of the RF signal, the plasma reaction chamber being the load supplying the RF signal.

[0034] Specifically, the RF power generator (110) may also include an RF control unit (200) for use with frequency control techniques for high-speed impedance matching. A detailed description of this will be provided in [reference needed]. Figure 2 Describe it.

[0035] The impedance matching device (120) can be implemented to match the impedance of the radio frequency signal output from the radio frequency power generator (110) with the impedance of the plasma reaction chamber (130). According to the implementation example, the impedance matching device (120) can be omitted.

[0036] Figure 2 This is a block diagram illustrating a radio frequency control device according to one embodiment. Figure 3 This is a flowchart illustrating a radio frequency control method according to one embodiment. Figures 4 to 7 This is a diagram illustrating the complex reflection coefficient plane to explain a radio frequency control method according to one embodiment.

[0037] Reference Figure 2 The radio frequency control device (200) may include a computing unit (210) and a tuning unit (220). The computing unit (210) and the tuning unit (220) may be implemented as a computer processor constituting the radio frequency control device (200), and may be separated or combined to express the functions of the processor. The computing unit (210) and the tuning unit (220), thus implemented as processors, can control the radio frequency control device (200) and further control the plasma processing device (100) to perform… Figure 3 The steps (S310, S320) included in the radio frequency control method shown. For example, the computing unit (210) and the tuning unit (220) can be implemented to execute instructions based on the operating system code and at least one program code of the computer device constituting the radio frequency control device (200).

[0038] Here, the calculation unit (210) and the tuning unit (220) can be expressions of different functions provided by the program code stored in the computer device constituting the radio frequency control device (200). For example, the calculation unit (210) can be used as a function to control the computer device to calculate the impedance trajectory circle of the load that provides the radio frequency signal to it on the complex reflection coefficient plane.

[0039] The steps (S310, S320) described below may be different from those described below. Figure 3 The steps shown are executed in sequence, and some steps in steps (S310, S320) may be omitted, or additional processes may be included.

[0040] In step (S310), the calculation unit (210) can calculate the impedance trajectory circle of the load (plasma reaction cavity (130)) that provides the radio frequency signal on the complex reflection coefficient plane.

[0041] Specifically, the calculation unit (210) can calculate the impedance trajectory circle by measuring the impedance at the load caused by the frequency change of the radio frequency signal.

[0042] More specifically, the calculation unit (210) can, by changing the frequency of the radio frequency signal to at least three or more values ​​and measuring the impedance at the load respectively, achieve the following: Figures 4 to 5 As shown, the impedance trajectory circle (500) connecting three or more points (410, 420, 430) on the complex reflection coefficient plane is directly derived and calculated. These three or more points correspond to the impedance at the load measured when the frequency of the RF signal is changed to at least three or more values.

[0043] In step (S320), the tuning unit (220) can use the impedance trajectory circle (500) to tune the frequency of the radio frequency signal to a frequency corresponding to the target impedance measured at the load.

[0044] Hereinafter, target impedance refers to the impedance measured in plasma reaction chamber (130) as a radio frequency signal is supplied to the plasma reaction chamber (130) as a load for plasma processing.

[0045] In this invention, the target impedance is not limited to the 50-ohm impedance corresponding to the output impedance of the RF power signal.

[0046] That is, the target impedance can be set to a complex impedance value different from 50 ohms, depending on the plasma process conditions, process steps, gas composition, power level, or operating state of the plasma reaction chamber.

[0047] More in detail, such as Figure 6As shown, the tuning unit (220) can generate a line (611) passing through the target point (610) on the complex reflection coefficient plane corresponding to the target impedance (since the impedance trajectory circle (500) is directly calculated and derived based on the impedance measured at the load when providing an RF signal to the load, the target point (610) exists on the impedance trajectory circle (500)) and the center point (510) of the impedance trajectory circle (500), and can generate a reference vector (511) passing through the origin of the complex reflection coefficient plane and the center point (510) of the impedance trajectory circle (500).

[0048] In this invention, the origin of the complex reflection coefficient plane is merely a reference point for defining the geometric reference vector for calculating the frequency, and does not imply that the RF signal must converge to the target impedance.

[0049] Next, as Figure 7 As shown, the tuning unit (220) determines the angle (θ) between the line (611) and the reference vector (511), calculates the frequency corresponding to the target impedance based on the determined angle, and then tunes the frequency of the radio frequency signal to the frequency corresponding to the calculated target impedance.

[0050] During the tuning process, after generating a frequency step based on the determined angle to calculate the frequency corresponding to the target impedance, the tuning unit (220) can tune the frequency of the radio frequency signal to the frequency corresponding to the target impedance by adding the generated frequency step to the frequency of the radio frequency signal.

[0051] Therefore, the present invention is applicable not only to 50-ohm impedance matching, but also to matching of complex impedances other than 50 ohms, and can achieve high-speed impedance matching optimized for plasma process conditions.

[0052] As described above, according to one embodiment, the radio frequency control device (200) uses the impedance trajectory circle (500) of the load calculated by measuring the impedance at the load due to the frequency change of the radio frequency signal to tune the frequency of the radio frequency signal, thereby achieving appropriate impedance matching in an environment where the impedance changes drastically in the plasma reaction chamber (130). Detailed Implementation

[0053] As described above, although embodiments have been described with reference to limited examples and accompanying drawings, those skilled in the art can make various modifications and variations from the above description. For example, suitable results can be achieved even if the described techniques are performed in a different order than the described methods, and / or the described systems, structures, devices, circuits, etc., are combined or integrated in a different form than the described methods, or are replaced or substituted by other components or equivalents.

[0054] Therefore, other implementations, other embodiments, and contents equivalent to the claims are all within the scope of the following claims.

Claims

1. A radio frequency control method, characterized in that, include: The steps for calculating the impedance trajectory circle of the load supplying the radio frequency signal on the complex reflection coefficient plane; as well as The step of tuning the frequency of the radio frequency signal to a frequency corresponding to the target impedance measured at the load using the impedance trajectory circle.

2. The radio frequency control method according to claim 1, characterized in that, The calculation step is to calculate the impedance trajectory circle by measuring the impedance at the load caused by the frequency change of the radio frequency signal.

3. The radio frequency control method according to claim 2, characterized in that, The calculation steps are as follows: by changing the frequency of the radio frequency signal to at least three or more values ​​and measuring the impedance at the load respectively, the impedance trajectory circle connecting three or more points on the complex reflection coefficient plane is calculated, where the three or more points correspond to the impedance at the load measured respectively when the frequency of the radio frequency signal is changed to at least three or more values.

4. The radio frequency control method according to claim 1, characterized in that, The tuning steps include: The steps of determining the angle between a line passing through the target point on the complex reflection coefficient plane corresponding to the target impedance and the center point of the impedance trajectory circle, and a reference vector passing through the origin of the complex reflection coefficient plane and the center point of the impedance trajectory circle; and The step of calculating the frequency corresponding to the target impedance based on the determined angle.

5. The radio frequency control method according to claim 4, characterized in that, The calculation steps include: Based on the determined angle, the step of generating a frequency step size for calculating the frequency corresponding to the target impedance; and The step of adding the generated frequency step size to the frequency of the radio frequency signal to tune the frequency of the radio frequency signal to a frequency corresponding to the target impedance.

6. A radio frequency control device, characterized in that, include: The calculation unit is used to calculate the impedance trajectory circle of the load that provides the radio frequency signal to the complex reflection coefficient plane. as well as The tuning section is used to tune the frequency of the radio frequency signal to a frequency corresponding to the target impedance measured at the load using the impedance trajectory circle.

7. The radio frequency control device according to claim 6, characterized in that, The calculation unit calculates the impedance trajectory circle by measuring the impedance at the load caused by the frequency change of the radio frequency signal.

8. The radio frequency control device according to claim 7, characterized in that, The calculation unit calculates the impedance trajectory circle connecting three or more points on the complex reflection coefficient plane by changing the frequency of the radio frequency signal to at least three or more values ​​and measuring the impedance at the load, wherein the three or more points correspond to the impedance at the load measured when the frequency of the radio frequency signal is changed to at least three or more values.

9. The radio frequency control device according to claim 6, characterized in that, The tuning unit determines the angle between a line passing through the target point on the complex reflection coefficient plane corresponding to the target impedance and the center point of the impedance trajectory circle, and a reference vector passing through the origin of the complex reflection coefficient plane and the center point of the impedance trajectory circle, and calculates the frequency corresponding to the target impedance based on the determined angle.

10. The radio frequency control device according to claim 9, characterized in that, Based on the determined angle, the tuning unit generates a frequency step size for calculating the frequency corresponding to the target impedance, and adds the generated frequency step size to the frequency of the radio frequency signal to tune the frequency of the radio frequency signal to the frequency corresponding to the target impedance.

11. The radio frequency control device according to claim 9, characterized in that, The target impedance includes a 50-ohm impedance, or a complex impedance value other than 50 ohms.

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