Real-time load impedance detection and rapid matching method

Abstract

The invention discloses a real-time load impedance detection and rapid matching method, and the method comprises the steps: firstly, connecting a voltage amplitude and phase detection module and a capacitance adjustment module to an L-type impedance matching network, and enabling the voltage amplitude and phase detection module to be used for measuring the voltages of different positions of the L-type impedance matching network; the capacitance adjusting module is used for adjusting the capacitance value of an adjustable capacitor in the L-shaped impedance matching network; the impedance value of the load is calculated according to the real-time detection value of the voltage amplitude and phase detection module, and then the input impedance value and the voltage reflection coefficient of the input end are calculated in sequence; and finally, comparing the voltage reflection coefficient of the input end with a set threshold value, calculating a capacitance value required by an adjustable capacitor in the L-shaped impedance matching network and adjusting the adjustable capacitor when the voltage reflection coefficient of the input end is greater than the threshold value, otherwise, not adjusting the adjustable capacitor. According to the invention, the impedance matching network is rapidly adjusted according to the load impedance value, the matching of the load impedance is realized, and the loss of reflection power is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of radio frequency impedance matching, and particularly to a method for real-time load impedance detection and rapid matching. Background Art

[0002] Radio frequency power supplies are widely used in fields such as plasma heating and semiconductor processes. Generally, such applications require a stable feed-in of radio frequency power. However, in reality, since the load connected to the radio frequency power supply is usually a plasma, due to the continuously changing state of the plasma and its non-linear effects, the equivalent load impedance value is not constant and fluctuates within a large range. The change in the load impedance causes a large mismatch between the radio frequency power supply and the load, and a large part of the power entering the load is reflected back to the radio frequency power supply. On the one hand, the changing power entering the load leads to an unstable process state; on the other hand, the reflected power causes power waste, and the large reflected power entering the radio frequency power supply may also damage the radio frequency power supply. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for real-time load impedance detection and rapid matching, which can quickly adjust the impedance matching network according to the load impedance value to achieve the matching of the load impedance and reduce the loss of reflected power.

[0004] The technical solution of the present invention is as follows: A method for real-time load impedance detection and rapid matching specifically includes the following steps: (1) Connect a voltage amplitude and phase detection module and a capacitance adjustment module to the L-type impedance matching network. The voltage amplitude and phase detection module includes a first voltage detection unit and a second voltage detection unit. One end of the first voltage detection unit is connected to the input end of the L-type impedance matching network and the other end is grounded. One end of the second voltage detection unit is connected to the output end of the L-type impedance matching network and the other end is grounded. The output end of the L-type impedance matching network is connected to the load, and the input end is connected to the radio frequency power supply; the capacitance adjustment module is used to adjust the capacitance value of the adjustable capacitor in the L-type impedance matching network. (2) Calculate the impedance value of the load from the voltage amplitude and phase detected in real time by the voltage amplitude and phase detection module, then calculate the input impedance value at the input end from the impedance value of the load, and then calculate the voltage reflection coefficient at the input end from the input impedance value at the input end. (3) Compare the voltage reflection coefficient at the input end with a set threshold: when the voltage reflection coefficient is greater than the threshold, calculate the capacitance value required for the adjustable capacitor in the L-type impedance matching network, and adjust the adjustable capacitor in the L-type impedance matching network to the required capacitance value through the capacitance adjustment module; when the voltage reflection coefficient is less than the threshold, keep the capacitance value of the adjustable capacitor unchanged.

[0005] The described L-shaped impedance matching network includes a first adjustable capacitor, a second adjustable capacitor, and a first inductor. The first adjustable capacitor is connected in parallel to the input end of the L-shaped impedance matching network. The first inductor and the second adjustable capacitor are connected in series between the input end and the output end of the L-shaped impedance matching network. The capacitor adjustment module includes a first capacitor adjustment component for adjusting the capacitance value of the first adjustable capacitor and a second capacitor adjustment component for adjusting the capacitance value of the second adjustable capacitor.

[0006] The described first voltage detection unit and second voltage detection unit are equivalent to two third capacitors and fourth capacitors connected in parallel to ground. One end of the third capacitor is connected to the input end of the L-shaped impedance matching network and the other end is grounded. One end of the fourth capacitor is connected to the output end of the L-shaped impedance matching network and the other end is grounded.

[0007] The impedance value of the load is calculated from the voltage amplitude and phase detected in real time by the voltage amplitude and phase detection module. The calculation process is shown in the following formula (1): (1); In formula (1), is the impedance value of the load, represents the voltage value detected in real time by the first voltage detection unit, represents the voltage value detected in real time by the second voltage detection unit, represents the imaginary unit, is the angular frequency, represents the capacitance value of the first adjustable capacitor, represents the capacitance value of the second adjustable capacitor, represents the inductance value of the first inductor; The described and are calculated by the following formula (2): (2); In formula (2), represents the amplitude value detected in real time by the first voltage detection unit, represents the amplitude value detected in real time by the second voltage detection unit, represents the phase value detected in real time by the first voltage detection unit, represents the phase value detected in real time by the second voltage detection unit.

[0008] The input impedance value at the input end is calculated from the impedance value of the load. The calculation process is shown in the following formula (3): (3); In formula (3), represents the input impedance value of the input terminal, represents the sum of the impedance values of the second adjustable capacitor, the first inductor, and the load, represents the imaginary unit, is the angular frequency, represents the capacitance value of the first adjustable capacitor, represents the capacitance value of the second adjustable capacitor, represents the inductance value of the first inductor.

[0009] The voltage reflection coefficient of the input terminal is calculated from the input impedance value of the input terminal. The calculation process is shown in the following formula (4): (4); In formula (4), represents the voltage reflection coefficient of the input terminal; represents the characteristic impedance.

[0010] The capacitance values required for the adjustable capacitors in the L-type impedance matching network are calculated. Specifically, the capacitance values required for the first adjustable capacitor and the second adjustable capacitor in the L-type impedance matching network are calculated by the following formula (5) and : (5); In formula (5), represents the real part of the load impedance, represents the imaginary part of the load impedance, is the angular frequency, represents the inductance value of the first inductor, represents the real part of the RF power supply impedance.

[0011] Advantages of the present invention: (1) The present invention is provided with a voltage amplitude and phase detection module to collect the voltage amplitude and phase information at the input and output ends of the impedance matching network. The phases of the two voltages are relative values, thus canceling out the additional errors introduced due to the defects in the acquisition accuracy. Compared with the method of simultaneously measuring voltage and current by the vector voltammetry method, the circuit design difficulty is reduced, and the result is more accurate; (2) The present invention quickly calculates the load impedance value based on the voltages collected by the voltage amplitude and phase detection module, and then performs the calculation of the matching network and the adjustment of the adjustable capacitor element values to achieve the matching of the load impedance, reduce the reflection power loss, the circuit structure is simple, and it has a high load impedance measurement accuracy and can be used in an automatic impedance matching system. Description of the Drawings

[0012] Figure 1It is an equivalent circuit diagram composed of the L-type impedance matching network, voltage amplitude and phase detection module, and capacitance adjustment module of the present invention.

[0013] Figure 2 It is a circuit diagram of the L-type impedance matching network of the present invention connected between a radio frequency power supply and a load. Specific embodiments

[0014] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0015] A real-time load impedance detection and rapid matching method specifically includes the following steps: (1), See Figure 1 And Figure 2 , Connect a voltage amplitude and phase detection module and a capacitance adjustment module to the L-type impedance matching network. The L-type impedance matching network includes a first adjustable capacitor C1, a second adjustable capacitor C2, and a first inductor L1. The first adjustable capacitor C1 is connected in parallel with the input terminal P1 of the L-type impedance matching network. The first inductor L1 and the second adjustable capacitor C2 are connected in series between the input terminal P1 and the output terminal P2 of the L-type impedance matching network. The input terminal P1 of the L-type impedance matching network is connected to the radio frequency power supply RFPS, and the output terminal P2 is connected to the load ZL; The voltage amplitude and phase detection module includes a first voltage detection unit and a second voltage detection unit. The first voltage detection unit and the second voltage detection unit are equivalent to two third capacitors C3 and fourth capacitors C4 connected in parallel to the ground. One end of the third capacitor C3 is connected to the input terminal P1 of the L-type impedance matching network, and the other end is grounded. One end of the fourth capacitor C4 is connected to the output terminal P2 of the L-type impedance matching network, and the other end is grounded; The capacitance adjustment module includes a first capacitance adjustment component T1 for adjusting the capacitance value of the first adjustable capacitor and a second capacitance adjustment component T2 for adjusting the capacitance value of the second adjustable capacitor. The first capacitance adjustment component T1 and the second capacitance adjustment component T2 can be selected as stepper motors. The stepper motors drive the sliding ends of the first adjustable capacitor C1 and the second adjustable capacitor C2 to slide to achieve capacitance value adjustment, or other adjustment structures can be used to achieve controllable adjustment of the capacitance values of the first adjustable capacitor C1 and the second adjustable capacitor C2; Among them, the first inductor L1 can also be provided with multiple gears to increase the adjustment range of impedance matching; (2) First, the impedance value of the load is calculated from the voltage amplitude and phase detected in real time by the voltage amplitude and phase detection module. The calculation process is shown in Equation (1) below: (1); In Equation (1), is the impedance value of the load, represents the voltage value detected in real time by the first voltage detection unit, represents the voltage value detected in real time by the second voltage detection unit, represents the imaginary unit, is the angular frequency, represents the capacitance value of the first adjustable capacitor C1, represents the capacitance value of the second adjustable capacitor C2, represents the inductance value of the first inductor L1; and are calculated from Equation (2) below: (2); In Equation (2), represents the amplitude value detected in real time by the first voltage detection unit, represents the amplitude value detected in real time by the second voltage detection unit, represents the phase value detected in real time by the first voltage detection unit, represents the phase value detected in real time by the second voltage detection unit; Then, from the impedance value of the load ZL, the input impedance value of the input terminal P1 is calculated. The calculation process is shown in Equation (3) below: (3); In Equation (3), represents the input impedance value of the input terminal, represents the sum of the impedance values of the second adjustable capacitor C2, the first inductor L1, and the load ZL, represents the imaginary unit, is the angular frequency, represents the capacitance value of the first adjustable capacitor C1, represents the capacitance value of the second adjustable capacitor C2, represents the inductance value of the first inductor L1; Then, from the input impedance value of the input terminal P1, the voltage reflection coefficient of the input terminal is calculated. The calculation process is shown in Equation (4) below: (4); In formula (4), represents the voltage reflection coefficient of the input terminal P1; represents the characteristic impedance, and its value is 50 Ω; (3), Compare the voltage reflection coefficient of the input terminal with the set threshold (1%): When the voltage reflection coefficient is greater than the threshold, the capacitance values required for the first adjustable capacitor and the second adjustable capacitor in the L-type impedance matching network are calculated by the following formula (5), and the adjustable capacitors in the L-type impedance matching network are adjusted to the required capacitance values through the capacitance adjustment module; when the voltage reflection coefficient is less than the threshold, the capacitance values of the adjustable capacitors remain unchanged.

[0016] Calculate the capacitance values required for the adjustable capacitors in the L-type impedance matching network. Specifically, the capacitances required for the first adjustable capacitor and the second adjustable capacitor in the L-type impedance matching network are calculated by the following formula (5) value and : (5); In formula (5), represents the real part of the load impedance, represents the imaginary part of the load impedance, represents the capacitance value required for the first adjustable capacitor in the L-type impedance matching network, represents the capacitance value required for the second adjustable capacitor in the L-type impedance matching network, is the angular frequency, represents the inductance value of the first inductor, represents the real part of the radio frequency power supply impedance.

[0017] Among them, formula (5) is derived from the following steps: When impedance matching is performed, for an ideal matching (i.e., no reflection) situation, the output impedance of the L-type impedance matching network satisfies the following formula (6): (6); In formula (6), is the conjugate of the load impedance; At the same time, because , ; Among them, is the real part of the output impedance, is the imaginary part of the output impedance, is the real part of the load impedance, the imaginary part of the load impedance; From this, the following formula (7) is obtained: (7); Then, the real part and the imaginary part of the output impedance Substitute the expression of Equation (6) into Equation (7), and Equation (5) can be obtained; (8);

[0018] Among them, the input impedance value and the radio frequency power supply impedance are in a conjugate relationship, is the radio frequency power supply impedance of the real part.

[0019] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A real-time load impedance detection and fast matching method, characterized in that: The specific steps include: (1) Connecting a voltage amplitude and phase detection module and a capacitance adjustment module to the L-type impedance matching network, wherein the voltage amplitude and phase detection module includes a first voltage detection unit and a second voltage detection unit, wherein one end of the first voltage detection unit is connected to the input end of the L-type impedance matching network and the other end is grounded, and one end of the second voltage detection unit is connected to the output end of the L-type impedance matching network and the other end is grounded, wherein the output end of the L-type impedance matching network is connected to the load and the input end is connected to the radio frequency power supply; the capacitance adjustment module is used to adjust the capacitance value of the adjustable capacitor in the L-type impedance matching network; (2) The impedance value of the load is calculated by the voltage amplitude and phase detected in real time by the voltage amplitude and phase detection module, and then the input impedance value of the input end is calculated by the impedance value of the load, and then the voltage reflection coefficient of the input end is calculated by the input impedance value of the input end; (3) Compare the voltage reflection coefficient at the input end with the set threshold value: when the voltage reflection coefficient is greater than the threshold value, the required capacitance value of the adjustable capacitor in the L-type impedance matching network is calculated, and the adjustable capacitor in the L-type impedance matching network is adjusted to the required capacitance value through the capacitance adjustment module; when the voltage reflection coefficient is less than the threshold value, the capacitance value of the adjustable capacitor is maintained unchanged.

2. A real-time load impedance detection and fast matching method according to claim 1, characterized in that: The L-type impedance matching network includes a first adjustable capacitor, a second adjustable capacitor and a first inductor. The first adjustable capacitor is connected in parallel with the input end of the L-type impedance matching network, and the first inductor and the second adjustable capacitor are connected in series between the input end and the output end of the L-type impedance matching network; the capacitance adjustment module includes a first capacitance adjustment component for adjusting the capacitance value of the first adjustable capacitor and a second capacitance adjustment component for adjusting the capacitance value of the second adjustable capacitor.

3. A real-time load impedance detection and fast matching method according to claim 2, characterized in that: The first voltage detection unit and the second voltage detection unit are equivalent to two third and fourth capacitors connected in parallel to the ground. One end of the third capacitor is connected to the input end of the L-type impedance matching network and the other end is grounded. One end of the fourth capacitor is connected to the output end of the L-type impedance matching network and the other end is grounded.

4. A real-time load impedance detection and fast matching method according to claim 2, characterized in that: The voltage amplitude and phase detected in real time by the voltage amplitude and phase detection module are used to calculate the impedance value of the load. The calculation process is shown in the following formula (1): （1）； In formula (1), is the impedance value of the load, represents the voltage value detected in real time by the first voltage detection unit, represents the voltage value detected in real time by the second voltage detection unit, represents the imaginary unit, is the angular frequency, represents the capacitance value of the first adjustable capacitor, represents the capacitance value of the second adjustable capacitor, represents the inductance value of the first inductor; The and It is calculated by the following formula (2): （2）； In formula (2), Represents the real-time detection of the first voltage detection unit The amplitude value of Represents the real-time detection of the second voltage detection unit The amplitude value of Represents the real-time detection of the first voltage detection unit The phase value of Represents the real-time detection of the second voltage detection unit The phase value of .

5. A real-time load impedance detection and fast matching method according to claim 4, characterized in that: The input impedance value of the input end is calculated from the impedance value of the load, and the calculation process is shown in the following formula (3): （3）； In formula (3), Represents the input impedance value of the input terminal, represents the sum of the impedance values ​​of the second adjustable capacitor, the first inductor and the load, represents the imaginary unit, is the angular frequency, represents the capacitance value of the first adjustable capacitor, represents the capacitance value of the second adjustable capacitor, Represents the inductance value of the first inductor.

6. A real-time load impedance detection and fast matching method according to claim 5, characterized in that: The voltage reflection coefficient of the input end is calculated from the input impedance value of the input end. The calculation process is shown in the following formula (4): （4）； In formula (4), Represents the voltage reflection coefficient at the input end; Represents characteristic impedance.

7. A real-time load impedance detection and fast matching method according to claim 6, characterized in that: The capacitance value required for the adjustable capacitor in the L-type impedance matching network is calculated by the following formula (5): and : （5）； In formula (5), represents the real part of the load impedance, represents the imaginary part of the load impedance, is the angular frequency, represents the inductance value of the first inductor, Represents the real part of the RF source impedance.

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