Impedance matching device

Abstract

The invention discloses an impedance matching device, which is applied to semiconductor process equipment, is connected between a radio frequency power generator and a reaction cavity, and comprises a matching network, and the matching network comprises a first capacitance adjusting module connected between the radio frequency power generator and the ground, and a second capacitance adjusting module connected between the radio frequency power generator and the reaction cavity; the first capacitance value is used for endowing a matching network with a first capacitance value with large-range adjustment capability; the second capacitance adjusting module is connected in parallel with the first capacitance adjusting module and is used for endowing the matching network with a second capacitance value with small-range adjusting capability; the third capacitor is electrically connected with the radio frequency power generator; and the inductance module is connected in series with the third capacitor.

Description

Technical Field

[0001] The present invention relates to the technical field of radio frequency impedance matching, and in particular to an impedance matching device. Background Art

[0002] RF power generator is a device used to generate RF power signals. It is a core component of semiconductor process equipment. All equipment that generates plasma for material processing requires RF power generators to provide energy. Process manufacturing equipment for integrated circuits, solar cells and LEDs (Light Emitting Diodes), such as etcher, PVD (Physical Vapor Deposition), PECVD (Plasma Enhanced Chemical Vapor Deposition), ALD (Atomic Layer Deposition) and other equipment, are equipped with RF power generators with different power specifications.

[0003] The RF power generator generally includes an RF power generator and an impedance matching circuit. The RF power generator is used to generate a RF signal with a certain power level and a certain frequency, and the impedance matching circuit is arranged between the plasma reaction chamber and the RF power generator to match the load impedance of the plasma reaction chamber with the output impedance of the RF power generator, so as to well transmit the power generated by the RF power generator to the plasma chamber, thereby exciting a sufficient amount of plasma to achieve the process requirements.

[0004] In the process of generating plasma for material processing, there is a plasma discharge process, and plasma discharge is a nonlinear process, so the load impedance reflected by the plasma reaction chamber (including the induction coil or antenna) is not a constant, and is basically closely related to the chamber gas pressure, RF power, and the composition and proportion of the process gas in the chamber. When these parameters change, the load impedance naturally changes; however, in the semiconductor process or material modification process, these parameters often fluctuate, so an impedance matcher is required to quickly track these changes to avoid the inability to properly deliver power to the chamber due to impedance mismatch, thereby hindering the process.

[0005] To solve this problem, the prior art usually uses a variable impedance element to adjust the impedance of the impedance matching circuit, and the impedance of the variable impedance element can be adjusted by adjusting the relative area of ​​the plates of a capacitor or the dielectric constant of the capacitor, etc., and then detected by a detection device and adjusted again, thereby achieving the purpose of adjusting the impedance of the impedance matching circuit.

[0006] In the above method, due to the error in the detection process, the matching algorithm is mainly a two-dimensional optimization process, which requires constant trial and comparison, that is, the process of "detection-calculation-comparison-adjustment", which takes a long time. However, in the use scenarios with high process requirements or harsh process conditions, such as larger chambers (chambers suitable for 450 mm wafers) and / or finer line widths (processes below 22 nanometers), process parameter changes are more sensitive, the above adjustment method cannot be tracked quickly, impedance matching is difficult, and these conditions are usually accompanied by high voltage or high current, which can easily cause device damage. Summary of the invention

[0007] The present invention aims to provide an impedance matching device to solve the problems of the prior art that the device cannot be quickly tracked, the impedance matching is difficult and the device is easily damaged.

[0008] In order to achieve the above technical objectives, the present application provides an impedance matching device, which is applied to semiconductor process equipment and connected between a radio frequency power generator and a reaction chamber, and includes a matching network, wherein the matching network includes: A first capacitance adjustment module, connected between the RF power generator and the ground, for giving the matching network a first capacitance value with a wide range of adjustment capability; A second capacitance adjustment module, connected in parallel with the first capacitance adjustment module, for giving the matching network a second capacitance value with a small range adjustment capability; a third capacitor electrically connected to the radio frequency power generator; The inductor module is connected in series with the third capacitor.

[0009] Preferably, the first capacitance adjustment module comprises a plurality of capacitors connected in parallel and a first switching module for controlling the plurality of capacitors, wherein the first switching module is used to switch on the selected capacitors through a switch control command.

[0010] Preferably, the second capacitance adjustment module has the same structure as the first capacitance adjustment module, but has different capacitance values.

[0011] Preferably, the first switching switch module comprises a switch controller and a switch respectively connected to each capacitor, and the switch controller is used to control the opening and closing of each switch.

[0012] Preferably, the first switch module includes a plurality of independent manual switches, and each manual switch is connected to a capacitor.

[0013] Preferably, the inductor module is an adjustable inductor.

[0014] Preferably, the inductor module comprises a first inductor, a second inductor and a third inductor with different inductance values ​​connected in parallel and a third switching module, and the third switching module is used to control the connectivity of the first inductor, the second inductor and the third inductor.

[0015] Preferably, the inductor module includes a non-adjustable inductor, and the third capacitor is a non-adjustable capacitor.

[0016] Preferably, the third capacitor has the same structure as the first capacitor adjustment module.

[0017] The present invention discloses the following technical effects: The present invention provides a first capacitor adjustment module for giving a matching network a first capacitance with a wide range of adjustment capability and a second capacitor adjustment module for giving a matching network a second capacitance with a small range of adjustment capability. Thus, the first capacitor adjustment module is used to directly determine a target impedance value, and then the second capacitor adjustment module is used to adjust the impedance within a smaller range. This avoids the problem that the impedance variation range is too large during the adjustment process, resulting in too large fluctuations, a long adjustment process, and easy damage to the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A schematic diagram of a functional module framework of an impedance matching device for implementing the present invention; Figure 2 for Figure 1 A schematic diagram of the composition of the first capacitance adjustment module shown; Figure 3 It is another structural schematic diagram of the inductance adjustment module adopted by the present invention; Figure 4 It is a schematic diagram of the functional module framework of the second embodiment of the impedance matching device of the present invention. DETAILED DESCRIPTION

[0020] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0021] See also Figure 1 FIG. 1 is a schematic diagram of a functional module framework of an impedance matching device for implementing the present invention. The impedance matching device for implementing the present invention is applied to semiconductor process equipment and connected between a radio frequency power generator and a reaction chamber, and includes a matching network, wherein the matching network includes: The first capacitance adjustment module 10 is connected between the RF power generator and the ground, and is used to give the matching network a first capacitance value with a wide range of adjustment capability; A second capacitance adjustment module 11, connected in parallel with the first capacitance adjustment module, is used to give the matching network a second capacitance with a small range adjustment capability; A third capacitor C3 is electrically connected to the radio frequency power generator; The inductor module 12 is connected in series with the third capacitor C3.

[0022] More preferably, if Figure 2 As shown, the first capacitance adjustment module 10 includes a plurality of capacitors connected in parallel and a first switching module for controlling the plurality of capacitors, and the first switching module includes a switch controller and a plurality of switches connected to the switch controller, each switch is connected to a capacitor, and the switch controller controls the selected switch to close so as to conduct the corresponding capacitor, thus outputting the first capacitance value. Figure 2 In the embodiment shown, four capacitors are provided, namely, capacitors C11, C12, C13, and C14, and first, second, third, and fourth switches are provided accordingly. In addition, the first capacitor adjustment module may also only include switches and corresponding capacitors, and the switches may be manual switches, such as the first, second, third, and fourth switches are all manual switches, and the operator presses the selected manual switch to select the corresponding capacitor to be turned on.

[0023] Further preferably, the structure of the second capacitance adjustment module 11 is Figure 2The structures of the first capacitance adjustment modules 10 shown in the figure are the same, except that the capacitance values ​​of the capacitors included in the two are different. The capacitance of the second capacitance adjustment module 11 (i.e. Figure 1 The capacitance value of the capacitors C21, C22, C23, and C24 in the capacitors is smaller than the capacitance of the first capacitance adjustment module 10 (i.e. Figure 1 Capacitors C11, C12, C13, C14 in the circuit).

[0024] Further preferably, the inductor module 12 includes a first inductor L1, a second inductor L2, and a third inductor L3 having different inductance values ​​connected in parallel and a third switching switch module, wherein the third switching switch module is used to control the connectivity of the first inductor L1, the second inductor L2, and the third inductor L3. The structure of the third switching switch module is similar to that of the first switching switch module, that is, the corresponding inductor is selected by selecting the closure of different switches.

[0025] More preferably, if Figure 3 As shown, the inductor module 12 includes a switch controller and fifth, sixth and seventh switches, and one end of each switch is connected to a different connection point of the adjustable inductor, so that by selecting different switches, the set inductor length can be selected to achieve the purpose of adjusting the inductance value.

[0026] More preferably, if Figure 4 As shown, in another embodiment of the present invention, the inductor module 12 includes only one non-adjustable inductor.

[0027] like Figure 1 As shown, the impedance matching device implementing the present invention also includes a detection unit and a control unit, wherein the detection unit is used to detect the power signal of the RF power output circuit and output it to the control unit, wherein the control unit is connected to the first, second and third switching switch modules to control the closing of different switches, thereby selecting corresponding capacitance and inductance values.

[0028] The detection unit is used to obtain parameters such as voltage, current, forward power, reverse power and input impedance of the impedance matching device on the transmission line between the RF power generator and the impedance matching device, and provide the control unit with the input quantity required by the matching algorithm. The voltage and current sensing circuit of the detection unit can adopt the method of capacitor voltage division and current transformer. These parameters are vector operated after sampling to calculate other parameters such as forward power, reverse power and input impedance of the impedance matching device. Based on these input quantities and with the help of a certain matching algorithm, the control unit calculates the adjustment amount of the variable impedance element and outputs it to the first, second and third switching switch modules. The first, second and third switching switch modules change the impedance value of the variable impedance element according to the received adjustment amount. This is described in many prior arts and will not be described in detail here.

[0029] Alternatively, the operator may set the impedance matching device according to the recommended value or prompt (such as the corresponding impedance value recommended according to the specific process requirements) on the host computer (not shown) of the semiconductor device implementing the impedance matching device of the present invention. Figure 1 and Figure 3 In the embodiment shown, the initial capacitance and inductance values ​​of the first capacitance adjustment module 10, the second capacitance adjustment module 11 and the inductance module 12 are adjusted by the control unit according to the measurement results of the detection unit. An ideal state is that the initial capacitance and inductance values ​​of the first capacitance adjustment module 10 and the inductance module 12 do not need to be adjusted, and only the output capacitance value of the second capacitance adjustment module 11 needs to be adjusted, so that impedance matching can be achieved quickly within a smaller fluctuation range. If necessary, the output values ​​of the first capacitance adjustment module 10 and the inductance module 12 are adjusted.

[0030] Alternatively, an algorithm model is provided in the control unit, and the algorithm model directly determines the optimal capacitance and inductance values ​​according to the measurement results of the detection unit, so that the control unit directly outputs corresponding control signals of the first capacitance adjustment module 10, the second capacitance adjustment module 11 and the inductance module 12 to select corresponding capacitance and inductance.

[0031] like Figure 4 In the illustrated embodiment, when the inductance is not adjustable, only the output values ​​of the first capacitance adjustment module 10 and the second capacitance adjustment module 11 can be adjusted, and the specific method is similar to the above method.

[0032] Furthermore, in a specific implementation, the capacitance value of the first capacitance adjustment module 10 can be 50, 75, 100, 125 (switched by the first switching switch module), and the capacitance value of the second capacitance adjustment module 11 can be 5, 10, 15, 20. In this way, if the capacitance value output by the first capacitance adjustment module 10 is 50, the capacitance reactance value (i.e., the sum of the two capacitors in parallel) of 55, 60, 65, 70 can be obtained by adjusting the second capacitance adjustment module 11. Of course, more capacitances can be set according to the specific situation to achieve a smaller adjustment range.

[0033] in addition, Figure 1 The third capacitor C3 shown in FIG. 1 is a fixed capacitor, which can also be set to the structure of the first capacitance adjustment module 10 , and the working principle is the same as above.

[0034] In the specific implementation, since the inductor will generate reverse electromotive force when switching during operation, Figure 1 and Figure 3In the scheme shown, dynamic adjustment of the inductance L during operation is avoided as much as possible. An inductance value can only be determined in advance through experience or a preset impedance matching table (that is, before the RF power generator starts working, the corresponding inductance value is first configured by the host computer), and then the capacitive reactance is adjusted through the first capacitor adjustment module 10 and the second capacitor adjustment module 11.

[0035] Compared with the prior art, the present invention provides a first capacitor adjustment module for giving the matching network a first capacitance with a wide range of adjustment capability and a second capacitor adjustment module for giving the matching network a second capacitance with a small range of adjustment capability. In this way, the first capacitor adjustment module is used to directly determine the target impedance value, and then the second capacitor adjustment module is used to adjust it within a smaller range. In this way, the impedance fluctuation is too large due to the large range of change during the adjustment process, and the adjustment process is long and easy to cause device damage.

[0036] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0037] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0038] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. An impedance matching device, applied to semiconductor process equipment and connected between a radio frequency power generator and a reaction chamber, comprising a matching network, characterized in that The matching network comprises: A first capacitance adjustment module, connected between the RF power generator and the ground, for giving the matching network a first capacitance value with a wide range of adjustment capability; A second capacitance adjustment module, connected in parallel with the first capacitance adjustment module, for giving the matching network a second capacitance value with a small range adjustment capability; a third capacitor electrically connected to the radio frequency power generator; The inductor module is connected in series with the third capacitor.

2. The impedance matching device according to claim 1, characterized in that: The first capacitance adjustment module includes a plurality of capacitors connected in parallel and a first switch module for controlling the plurality of capacitors. The first switch module is used to switch on the selected capacitors through a switch control command.

3. The impedance matching device according to claim 2, characterized in that: The second capacitance adjustment module has the same structure as the first capacitance adjustment module, but has different capacitance values.

4. The impedance matching device according to claim 3, characterized in that: The first switching switch module includes a switch controller and switches respectively connected to each capacitor, and the switch controller is used to control the opening and closing of each switch.

5. The impedance matching device according to claim 4, characterized in that: The first switch module includes a plurality of independent manual switches, and each manual switch is connected to a capacitor.

6. The impedance matching device according to claim 4 or 5, characterized in that: The inductor module is an adjustable inductor.

7. The impedance matching device according to claim 6, characterized in that: The inductor module includes a first inductor, a second inductor and a third inductor with different inductance values ​​connected in parallel and a second switching module, and the second switching module is used to control the connectivity of the first inductor, the second inductor and the third inductor.

8. The impedance matching device according to claim 4 or 5, characterized in that: The inductor module includes a non-adjustable inductor, and the third capacitor is a non-adjustable capacitor.

9. The radio frequency matching circuit according to claim 1, characterized in that: The third capacitor has the same structure as the first capacitor adjustment module.

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