SYSTEM AND METHOD FOR CONTROLLING A FAST ACTUATOR IN AN IMPEDANCE MATCHING UNIT - Patent application

Abstract

A system and method for controlling a fast actuator in an impedance matching unit are described. The impedance matching unit includes an input port coupled to a radio frequency (RF) generator. The impedance matching unit further includes an output port coupled to a plasma chamber. The impedance matching unit includes a connection point located between the input port and the output port, a first reactive element coupled between the input port and the connection point, and a first switch coupled in parallel to the first reactive element. The impedance matching unit includes a second reactive element coupled between the connection point and the output port, and a second switch coupled in parallel to the second reactive element.

Description

[Technical Field]

[0001] The present embodiments relate to a system and method for controlling a high speed actuator in an impedance matching unit. [Background technology]

[0002] Semiconductor devices are fabricated using plasma processing, which involves introducing radio frequency (RF) energy to excite gas molecules in a gas mixture to form a plasma. The plasma is contained in a partial vacuum chamber called a process chamber, and RF energy is introduced into the process chamber through antennas and / or electrodes.

[0003] In a plasma process, an RF generator supplies power at a high frequency, and this power is generally transmitted through an RF cable, which typically has an impedance of 50 ohms. To match impedances, such as the load impedance of the processing chamber and the source impedance of the RF generator, an RF matching network is installed between the RF generator and the processing chamber. A semiconductor wafer is placed in the processing chamber to be processed with RF energy. To achieve efficient power transmission from the RF generator to the processing chamber, the RF matching network is used to match the variable impedance of the processing chamber with the fixed impedance of the RF generator.

[0004] The purpose of an RF matching network is to transform the load impedance presented by the processing chamber containing the plasma into a value that absorbs RF power before it is reflected back toward the RF generator. While a strict 50 ohm match is not required, if there is a mismatch between the source impedance and the load impedance, some of the RF power will be reflected back toward the RF generator. Often, especially in semiconductor fabrication processes, the impedance of the RF generator is fixed at 50 ohms, and RF power is transmitted through an RF cable that also has a fixed 50 ohm impedance. Unlike the impedance of the RF generator and RF cable, the impedance of the plasma driven by the RF power varies. To efficiently transmit RF power from the RF generator and RF cable to the processing chamber, the impedance of the processing chamber is transformed to a non-reactive 50 ohm. This maximizes the amount of RF power transmitted to the processing chamber. However, the interaction of the RF matching network with the plasma impedance and source impedance can cause problems with plasma ignition, impedance mismatch, and plasma instability. Therefore, using an RF matching network can make it difficult to process substrates using an RF generator.

[0005] The background description provided herein is intended to present the contents of the present disclosure generally. Work by the presently named inventors within the scope of what is described in this Background section, as well as aspects of the description that may not otherwise be considered prior art at the time of filing, are not admitted, expressly or impliedly, as prior art against the present disclosure. Summary of the Invention

[0006]

[0010] The embodiments of the present disclosure provide a system, an apparatus, a method, and a computer program for controlling a high-speed actuator in an impedance matching unit. It should be understood that the embodiments can be implemented in numerous ways, for example, as a process, an apparatus, a system, a device, or a method on a computer-readable medium. Some embodiments are described below.

[0007] In one embodiment, an impedance matching unit is described. The impedance matching unit includes an input port coupled to a radio frequency (RF) generator. The impedance matching unit further includes an output port coupled to a plasma chamber. The matcher includes a connection point located between the input port and the output port, a first reactive element coupled between the input port and the connection point, and a first switch coupled in parallel to the first reactive element. The impedance matching unit includes a second reactive element coupled between the connection point and the output port, and a second switch coupled in parallel to the second reactive element.

[0008] In one embodiment, an impedance matching unit is described. The impedance matching unit includes an input port coupled to an RF generator, an output port coupled to a plasma chamber, and a first connection point located between the input port and the output port. The impedance matching unit further includes a second connection point located between the input port and the output port, a first reactive element coupled to the first connection point, and a first switch coupled in series with the first reactive element. The first switch is coupled to a ground potential. The impedance matching unit includes a second reactive element coupled to the second connection point and a second switch coupled in series with the second reactive element. The second switch is coupled to a ground potential.

[0009] In one embodiment, a method is described. The method includes receiving a measurement value of a parameter indicative of plasma stability in a plasma chamber. The parameter measurement value is received from one or more sensors, such as a voltage sensor, a current sensor, a phase sensor, an optical signal sensor, or an impedance sensor. The method further includes determining multiple positions of multiple switches in an impedance matching unit based on the measurement value of the parameter. The impedance matching unit is located between an RF generator and the plasma chamber. Each of the multiple switches is in parallel with a corresponding one of multiple reactive elements of the impedance matching unit. The method includes controlling the multiple switches to be in multiple positions to achieve plasma stability.

[0010] Some advantages of the system and method for controlling a fast actuator in an impedance matching unit described herein include rapidly changing the reactance of the impedance matching unit and synchronizing the operation of the impedance matching unit with the operation of the RF generator. For example, when the state of an RF signal generated by an RF generator changes, the impedance matching unit is controlled via one or more switches to rapidly modify the reactance of the impedance matching unit. Mechanical control of the variable reactor (e.g., a variable capacitor or variable inductor) of the impedance matching unit by using a motor is not required. The reactance of the impedance matching unit is modified to match the impedance of a load coupled to the output of the impedance matching unit with the impedance of a source coupled to the input of the impedance matching unit. In one example, the load is a combination of an RF transmission line and a plasma chamber, and the source is a combination of an RF generator and an RF cable. By rapidly modifying the reactance of the impedance matching unit, plasma stability is achieved, and a substrate placed in the plasma chamber is processed in a desired manner.

[0011] Another advantage of the system and method for controlling a fast actuator in an impedance matching unit described herein is that the reactance of the impedance matching unit can be quickly changed without controlling a variable reactor of the impedance matching unit via a motor. When the reactance of the impedance matching unit is modified by controlling a motor coupled to a capacitor or inductor, it takes longer to modify the reactance than when a switch is used. Therefore, by using a switch, the reactance of the impedance matching unit is modified more quickly, e.g., at a higher speed, compared to when a motor is used to control the reactance. By quickly modifying the reactance, plasma stability is achieved through fast changes in the RF signal state, and semiconductor wafers are processed in a desired manner.

[0012] Additional advantages of the systems and methods described herein include reducing plasma instabilities, such as reducing or eliminating changes in the occurrence of plasma instabilities before they occur. Using a fast actuator to control the impedance matching unit before instabilities occur reduces the likelihood of instabilities occurring. For example, plasma instabilities can occur when an RF generator changes the power level state of an RF signal generated by the RF generator from a first state to a second state. Using a fast actuator to control the impedance matching unit immediately after the change in the state of the RF signal reduces the likelihood of plasma instabilities occurring.

[0013] Other aspects will become apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0014] The embodiments can be best understood by referring to the following description taken in conjunction with the accompanying drawings.

[0015] [Figure 1A]FIG. 1A is a diagram of one embodiment of a system illustrating the control of an actuator to control the series reactance of an impedance matching unit.

[0016] [Figure 1B] FIG. 1B shows one embodiment of a table illustrating a method for operating the switches of the impedance matching unit of FIG. 1A.

[0017] [Figure 2A] FIG. 2A is a diagram of one embodiment of a system illustrating the control of an actuator to control the shunt reactance of an impedance matching unit.

[0018] [Figure 2B] FIG. 2B shows one embodiment of a table illustrating a method for operating the switches of the impedance matching unit of FIG. 2A.

[0019] [Figure 3] FIG. 3 is a diagram of an embodiment of a system illustrating an impedance matching unit with a binary split network.

[0020] [Figure 4] FIG. 4 is a diagram of an embodiment of a plasma system illustrating control of one or more reactive elements of an impedance matching unit based on feedback from one or more sensors.

[0021] [Figure 5] FIG. 5 is a diagram of an embodiment of a plasma system illustrating control of the reactance of the reactive elements of the impedance matching unit of FIG. 4 based on a change in state of a variable of a radio frequency (RF) signal.

[0022] [Figure 6]FIG. 6 is a diagram of one embodiment of a plasma system illustrating control of the impedance matching unit of FIG. 4 based on conditions identified in a recipe for the RF signal.

[0023] [Figure 7A] FIG. 7A is a diagram of one embodiment of a table illustrating the correspondence between the reactance of the impedance matching unit of FIG. 4, the position of the switch of the impedance matching unit, and the state of the RF signal.

[0024] [Figure 7B] FIG. 7B is a diagram of one embodiment of a table illustrating the correspondence between the reactance of the impedance matching unit of FIG. 4, the switch position of the impedance matching unit of FIG. 4, and the state of the RF signal. DETAILED DESCRIPTION OF THE INVENTION

[0025] The following embodiments describe systems and methods for controlling a high-speed actuator in an impedance matching unit. It will be apparent that the embodiments may be practiced without some or all of these specific details. In other instances, well-known operations have not been described in detail so as not to unnecessarily obscure the embodiments.

[0026] 1A is a diagram of one embodiment of a system 100 illustrating control of actuators, such as switches SW1 and SW2, to control the series reactance of an impedance matching unit 102. By way of example, each switch described herein is a transistor, a group of transistors, or a vacuum relay. One example of a transistor is a field-effect transistor (FET), such as a radio frequency (RF) power FET. The system 100 includes a host computer 104, an RF generator 106, an impedance matching unit 102, and a plasma chamber 108. The host computer 104 includes a processor system 110 and a memory device 112. The impedance matching unit 102 includes a reactive element X1 and another reactive element X2.

[0027] Examples of the host computer 104 include a desktop computer, a laptop computer, a tablet, a controller, and a smartphone. For example, the RF generator 106 is a 100 kilohertz (kHz) RF generator, a 400 kHz RF generator, a 2 megahertz (MHz) RF generator, a 27 MHz RF generator, or a 60 MHz RF generator. Examples of the impedance matching unit 102 include an impedance matching network, an impedance matching circuit, a matcher, and an impedance matcher. For example, the impedance matching unit 102 includes a network in which reactive elements, such as series reactive elements, shunt reactive elements, or a combination thereof, are coupled to each other. Examples of the plasma chamber 108 include a capacitively coupled plasma (CCP) chamber and an inductively coupled plasma (ICP) chamber.

[0028] As an example, the processor system 110 includes one or more processors. Illustratively, a processor, as used herein, is an application-specific integrated circuit (ASIC), a central processing unit (CPU), a field-programmable gate array (FPGA), a programmable logic device (PLD), an integrated controller, or a microcontroller. Examples of memory devices, as used herein, include read-only memory (ROM) and random-access memory (RAM). Illustratively, the memory device 112 is a flash memory or a redundant array of independent disks (RAID).

[0029] Examples of reactive elements include inductors and capacitors. For example, reactive element X1 is an inductor or a capacitor, and reactive element X2 is an inductor or a capacitor.

[0030] The processor system 110 is coupled to a memory device 112. The processor system 110 is also coupled to the RF generator 106 via a transfer cable 114. Examples of transfer cables include a cable that allows for serial transfer of data, or a cable that allows for parallel transfer of data, and a cable that allows for transfer of data using the Universal Serial Bus (USB) protocol.

[0031] The RF generator 106 is coupled to an input port 118 of the impedance matching unit 102 via an RF cable 116, such as a coaxial cable. As used herein, an example of a port is a connector that couples two or more conductors together. The input port 118 is coupled to a node NX11 via an RF line 120. As used herein, an example of a node is a point at which two or more conductors are coupled to each other, such as by soldering. As used herein, a node or port may also be referred to as a connection point. The node NX11 is coupled to a terminal T11 of a switch SW1 via an RF line 122. As an example, an RF line, as used herein, refers to one or more conductors. In this example, two or more of the conductors are coupled to each other. Another terminal T12 of the switch SW1 is coupled to a node NX12 via an RF line 124. Because the node NX11 is coupled to the switch SW1 and the reactive element X1, and the node NX12 is coupled to the switch SW1 and the reactive element X1, the reactive element X1 is coupled in parallel to the switch SW1. Reactance element X1 is coupled to node NX11 via RF line 126 and to node NX12 via RF line 128.

[0032] Node NX12 is coupled to node NX21 via RF line 130. Node NX21 is coupled to terminal T21 of switch SW2 via RF line 131. Another terminal T22 of switch SW2 is coupled to node NX22 via RF line 132. Because node NX21 is coupled to switch SW2 and reactance element X2 and node NX22 is coupled to switch SW2 and reactance element X2, reactance element X2 is coupled in parallel to switch SW2.

[0033] Node NX21 is coupled to reactive element X2 via RF line 134, and reactive element X2 is coupled to node NX22 via RF line 136. Node NX22 is coupled to output port 140 of impedance matching unit 102 via RF line 138. Output port 140 is coupled to an electrode of plasma chamber 108 via RF strap 142. By way of example, RF strap 142 is a flat strap made of a metal such as copper. By way of example, RF strap 142 is not an RF cable and does not have a 50 ohm impedance. By way of further example, the length of RF strap 142 is shorter than the length of RF cable 116. For example, RF cable 116 has a length ranging from 4 feet (1.22 m) to 30 feet (9.14 m), and RF strap 142 is less than 1 foot (0.30 m) long. Examples of electrodes include a substrate support, an upper electrode, and a transformer-coupled plasma (TCP) coil. For example, if the plasma chamber 108 is a CCP chamber, the electrode coupled to the RF strap 142 is a substrate support or an upper electrode. For example, if the RF strap 142 is coupled to the substrate support, the upper electrode of the CCP chamber is coupled to ground potential or to an RF generator via an impedance matching unit. Furthermore, for example, if the RF strap 142 is coupled to the upper electrode, the substrate support is coupled to an RF generator via an impedance matching unit. For another example, if the plasma chamber 108 is an ICP chamber, the electrode coupled to the RF strap 142 is a substrate support or a TCP coil. For example, if the electrode coupled to the RF strap 142 is a substrate support, the TCP coil is coupled to ground potential or to an RF generator via an impedance matching unit. Furthermore, for example, if the electrode coupled to the RF strap 142 is a TCP coil, the substrate support is coupled to an RF generator via an impedance matching unit. An example of a substrate support is an electrostatic chuck (ESC).The processor system 110 is also coupled to a switch SW1 via a switch connection CSW1 and to a switch SW2 via another switch connection CSW2. As an example, a switch connection is one or more conductors. In this example, two or more of the conductors are coupled to each other.

[0034] It should be noted that when the switch of the impedance matching unit described herein is a transistor or a group of transistors, the processor system 110 is coupled to the switch through an RF filter to protect the processor system 110. The RF filter filters out RF power reflected from the plasma chamber 108 through the impedance matching unit to the processor system 110, thereby protecting the processor system 110. The RF filter is coupled between the processor system 110 and the switch. For example, one end of the RF filter is coupled to the processor system 110, and the other end of the RF filter is coupled to the switch.

[0035] Upon receiving a trigger signal from the processor system 110 via the transfer cable 114, the RF generator 106 generates an RF signal 144 and transmits the RF signal 144 to the node NX11 via the RF cable 116, the input port 118, and the RF line 120. One example of the RF signal 144 is a continuous wave. Another example of the RF signal 144 is a multi-state RF signal. The processor system 110 generates an OFF control signal and transmits the OFF control signal to the switch SW1 via the switch connection CSW1. In response to receiving the OFF control signal, the terminal T11 is disconnected from the terminal T12, and the switch SW1 is in an open state. Similarly, the processor system 110 generates an OFF control signal and transmits the OFF control signal to the switch SW2 via the switch connection CSW2. In response to receiving the OFF control signal, the terminal T21 is disconnected from the terminal T22, and the switch SW2 is in an open state. Note that when a switch described herein is in an open state, the switch is in an open position.

[0036] When switches SW1 and SW2 are open, RF signal 144 is transferred through reactive elements X1 and X2 coupled in series, and the impedance of RF signal 144 is modified by reactive elements X1 and X2 to output modified RF signal 146A. For example, reactive elements X1 and X2 match the impedance of a load coupled to output port 140 to the impedance of a source coupled to input port 118, outputting modified RF signal 146A based on RF signal 144. Examples of a load coupled to output port 140 include RF strap 142 and plasma chamber 108, and examples of a source coupled to input port 118 include RF generator 106 and RF cable 116. Modified RF signal 146A is transmitted from node NX22 to an electrode of plasma chamber 108 via RF line 138, output port 140, and RF strap 142.

[0037] When one or more process gases, such as an oxygen-containing gas, a nitrogen-containing gas, a fluorine-containing gas, or a combination thereof, are supplied to the plasma chamber 108 along with the modified RF signal 146A, a plasma is generated or maintained in the plasma chamber 108. A substrate, such as a semiconductor wafer, is placed on a substrate support in the plasma chamber 108 for processing with the plasma. Examples of substrate processing include depositing material on the substrate, etching the substrate, and cleaning the substrate.

[0038] As a first alternative means of transmitting OFF control signals to switches SW1 and SW2, the processor system 110 generates an ON control signal and transmits the ON control signal to switch SW1 via switch connection CSW1. In response to receiving the ON control signal, terminal T11 is connected to terminal T12, and switch SW1 is in a closed state. The processor system 110 generates an OFF control signal and transmits it via switch connection CSW2, opening switch SW2. Note that when a switch is in a closed state as described herein, the switch is in a closed position.

[0039] When switch SW1 is closed and switch SW2 is open, reactive element X1 acts as a short circuit, and RF signal 144 is transferred to reactive element X2 through the short circuit, node NX12, and RF line 130. The impedance of RF signal 144 is not modified by reactive element X1, but is modified by reactive element X2, outputting modified RF signal 146B. For example, reactive element X2 matches the impedance of a load coupled to output port 140 to the impedance of a source coupled to node NX21, outputting modified RF signal 146B at node NX22 based on RF signal 144. An example of a source coupled to node NX21 is the short circuit, RF cable 116, and RF generator 106. Modified RF signal 146B is transmitted from node NX22 through RF line 138, output port 140, and RF strap 142 to an electrode of plasma chamber 108. When one or more process gases are supplied to the plasma chamber 108 along with the modified RF signal 146B, a plasma is generated or maintained within the plasma chamber 108 to process the substrate.

[0040] As a second alternative means of transmitting OFF control signals to switches SW1 and SW2, processor system 110 generates an ON control signal and transmits the ON control signal to switch SW2 via switch connection CSW2. In response to receiving the ON control signal, terminal T21 is connected to terminal T22, and switch SW2 is closed. Processor system 110 generates an OFF control signal and transmits it via switch connection CSW1, opening switch SW1.

[0041] When switch SW2 is closed and switch SW1 is open, reactive element X2 acts as a short circuit, and RF signal 144 is transferred to the short circuit through reactive element X1. The impedance of RF signal 144 is modified by reactive element X1 without being modified by reactive element X2, resulting in modified RF signal 146C. For example, reactive element X1 matches the impedance of a load coupled to node NX12 to the impedance of a source coupled to input port 118, outputting modified RF signal 146C at node NX12 based on RF signal 144. An example of a load coupled to node NX12 includes the short circuit, RF strap 142, and plasma chamber 108. Modified RF signal 146C is transmitted from node NX12 to an electrode of plasma chamber 108 via RF line 130, the short circuit, RF line 138, output port 140, and RF strap 142. When one or more process gases are supplied to the plasma chamber 108 along with the modified RF signal 146C, a plasma is generated or maintained within the plasma chamber 108 to process the substrate.

[0042] As a third alternative means of transmitting OFF control signals to switches SW1 and SW2, processor system 110 generates an ON control signal and transmits the ON control signal to switch SW1 via switch connection CSW1. Processor system 110 also generates an ON control signal and transmits the ON control signal to switch SW2 via switch connection CSW2. In response to receiving the ON control signal, both switches SW1 and SW2 are closed.

[0043] When switches SW1 and SW2 are closed, reactive elements X1 and X2 act as short circuits, and RF signal 144 is forwarded to the short circuit of impedance matching unit 102 via input port 118. The impedance of RF signal 144 is substantially unmodified, such as unmodified or modified below a predetermined threshold, to output modified RF signal 146D at output port 140. For example, the short circuit matches the impedance of a load coupled to output port 140 to the impedance of a source coupled to input port 118, outputting modified RF signal 146D. Illustratively, modified RF signal 146D is the same as RF signal 144. Further illustratively, RF signal 144 is forwarded to output port 140 via RF line 120, node NX11, the first short circuit, node NX12, RF line 130, the second short circuit, node NX22, and RF line 138. The modified RF signal 146D is transmitted from the output port 140 through the RF strap 142 to an electrode of the plasma chamber 108. When one or more process gases are supplied to the plasma chamber 108 in addition to the modified RF signal 146D, a plasma is generated or maintained in the plasma chamber 108 to process a substrate.

[0044] In one embodiment, RF line 130 is replaced with a reactive element, for example, a series or shunt reactive element is placed in place of RF line 130 coupled between nodes NX12 and NX21.

[0045] In one embodiment, RF strap 142 is replaced by a series of RF straps that are bonded together.

[0046] FIG. 1B is one embodiment of a table 160 illustrating a method for operating switches SW1 and SW2. When switches SW1 and SW2 are both open, the combined reactance of reactive elements X1 and X2 is applied to RF signal 144 to modify the impedance of RF signal 144 and output modified RF signal 146A ( FIG. 1A ). Examples of reactance include capacitive reactance and inductive reactance. When switch SW1 is closed and switch SW2 is open, the reactance of reactive element X2 is applied to RF signal 144 without applying the reactance of reactive element X1 to modify the impedance of RF signal 144 and output modified RF signal 146B ( FIG. 1A ). When switch SW2 is closed and switch SW1 is open, the reactance of reactive element X1 is applied to RF signal 144 without applying the reactance of reactive element X2 to modify the impedance of RF signal 144 and output modified RF signal 146C. When switch SW1 is closed and switch SW2 is closed, the reactance of reactive elements X1 and X2 is not applied to RF signal 144, outputting modified RF signal 146D without substantially modifying the impedance of RF signal 144.

[0047] 2A is a diagram of one embodiment of a system 200 illustrating control of actuators such as switches SWa and SWb to control the shunt reactance of an impedance matching unit 202. The system 200 includes a host computer 104, an RF generator 106, an impedance matching unit 202, and a plasma chamber 108. The impedance matching unit 102 includes a reactance element Xa, another reactance element Xb, and yet another reactance element X. As an example, the reactance element Xa is an inductor or a capacitor, the reactance element Xb is an inductor or a capacitor, and the reactance element X is a capacitor or an inductor.

[0048] The RF generator 106 is coupled to an input port 204 of the impedance matching unit 202 via an RF cable 116. The input port 204 is coupled to a reactance element X via an RF line 206. The reactance element X is coupled to a node Nxa via an RF line 208. The node Nxa is coupled to a reactance element Xa via an RF line 210. The reactance element Xa is coupled to a terminal Ta1 of a switch SWa via an RF line 212 and is coupled in series with the switch SWa. The opposite terminal Ta2 of the switch SWa is coupled to ground potential. The node Nxa is also coupled to a node Nxb via an RF line 214. The node Nxb is coupled to a reactance element Xb via an RF line 216. The reactance element Xb is coupled to a terminal Tb1 of a switch SWb via an RF line 218 and is coupled in series with the switch SWb. The opposite terminal Tb2 of the switch SWb is coupled to ground potential. Node Nxb is coupled to an output port 222 of impedance matching unit 202 via RF line 220. Output port 222 is coupled to an electrode of plasma chamber 108 via RF strap 142. Additionally, processor system 110 is coupled to switch SWa via switch connection CSWa and to switch SWb via another switch connection CSWb.

[0049] RF signal 144 is transmitted from RF generator 106 through RF cable 116, input port 204, and RF line 206 to reactive element X. Reactive element X modifies the impedance of RF signal 144 to output modified RF signal 224a, which is forwarded to node Nxa.

[0050] The processor system 110 generates an off control signal and sends it to the switch SWa via the switch connection CSWa. In response to receiving the off control signal, the terminal Ta2 is disconnected from the terminal Ta1, and the switch SWa is open. Similarly, the processor system 110 generates an off control signal and sends it to the switch SWb2 via the switch connection CSWb. In response to receiving the off control signal, the terminal Tb2 is disconnected from the terminal Tb1, and the switch SWb is open. When the switches SWa and SWb are open, both the reactive elements Xa and Xb act as open circuits, and the modified RF signal 224a is transferred from the node Nxa to the electrode of the plasma chamber 108 via the RF line 214, the node NXb, the RF line 220, the output port 222, and the RF strap 142. When one or more process gases are supplied to the plasma chamber 108 along with the modified RF signal 224a, a plasma is generated or maintained in the plasma chamber 108.

[0051] As a first alternative means of transmitting OFF control signals to switches SWa and SWb, processor system 110 generates an ON control signal and transmits the ON control signal to switch SWa via switch connection CSWa. In response to receiving the ON control signal, terminal Ta2 is connected to terminal Ta1, and switch SWa is closed. Processor system 110 generates an OFF control signal and transmits it via switch connection CSWb, opening switch SWb.

[0052] When switch SWa is closed and switch SWb is open, reactive element Xb acts as an open circuit, reactive element Xa acts as a shunt circuit, and modified RF signal 224a is transferred to node Nxa through RF line 208. Reactive element Xa modifies the impedance of modified RF signal 224a and outputs modified RF signal 224b at node Nxa. Reactive element Xb does not modify the impedance of modified RF signal 224b. Modified RF signal 224b is transferred from node Nxa through RF line 214, node Nxb, RF connection line 220, and RF strap 142 to an electrode of plasma chamber 108. When one or more process gases are supplied to plasma chamber 108 along with modified RF signal 224b, a plasma is generated or maintained in plasma chamber 108 to process a substrate.

[0053] As a second alternative means of transmitting the OFF control signal to switches SWa and SWb, the processor system 110 generates an OFF control signal and transmits the OFF control signal to switch SWa via switch connection CSWa to open switch SWa. The processor system 110 also generates an ON control signal and transmits an ON control signal to switch SWb via switch connection CSWb to close switch SWb. In response to receiving the ON control signal, terminal Tb2 is connected to terminal Tb1, and switch SWb is in a closed state.

[0054] When switch SWa is open and switch SWb is closed, reactive element Xa acts as an open circuit, reactive element Xb acts as a shunt circuit, and modified RF signal 224a is transferred to node Nxb via RF line 208, node Nxa, and RF line 214. Reactive element Xa does not modify the impedance of modified RF signal 224a. Reactive element Xb modifies the impedance of modified RF signal 224a at node Nxb, outputting modified RF signal 224c at node Nxb. Modified RF signal 222c is transferred from node Nxb to an electrode of plasma chamber 108 via RF line 220, output port 222, and RF strap 142. When one or more process gases are supplied to plasma chamber 108 along with modified RF signal 224c, a plasma is generated or maintained in plasma chamber 108 to process a substrate.

[0055] As a third alternative means of transmitting the OFF control signal to switches SWa and SWb, processor system 110 generates an ON control signal and transmits the ON control signal to switch SWa via switch connection CSWa. Processor system 110 also generates an ON control signal and transmits the ON control signal to switch SWb via switch connection CSWb. In response to receiving the ON control signal, both switches SWa and SWb are closed.

[0056] When switches SWa and SWb are closed, reactive elements Xa1 and Xb act as a shunt circuit, and RF signal 224a is transmitted from reactive element Xa1 through RF line 208 to node Nxa, outputting modified RF signal 224b at node Nxa. Modified RF signal 224b is also transmitted through RF line 214 to node Nxb. Reactive element Xb modifies the impedance of modified RF signal 224b at node Nxb, outputting modified RF signal 224d at node Nxb. Modified RF signal 224d is transferred from node Nxb through RF line 220, output port 222, and RF strap 142 to an electrode of plasma chamber 108. When one or more process gases are supplied to plasma chamber 108 along with modified RF signal 222d, a plasma is generated or maintained in plasma chamber 108 to process a substrate.

[0057] In one embodiment, reactive element X is coupled between nodes Nxa and Nxb, or between node Nxb and output port 222, instead of being coupled between input port 204 and node Nxa.

[0058] 2B is one embodiment of table 160 illustrating a method for operating switches SWa and SWb. When switch SWa is open, the reactance of reactive elements Xa and Xb is not applied to modified RF signal 224a, outputting modified RF signal 224a at output port 222 without substantially modifying the impedance of modified RF signal 224a. When switch SWa is closed and switch SWb is open, the reactance of reactive element Xa is applied to modified RF signal 224a without applying the reactance of reactive element Xb, outputting modified RF signal 224b (FIG. 1A). When switch SWb is closed and switch SWa is open, the reactance of reactive element Xb is applied to RF signal 224a without applying the reactance of reactive element Xa, modifying the impedance of RF signal 224a and outputting modified RF signal 224c. When switches SWa and SWb are both closed, the combined reactance of reactive elements Xa and Xb is applied to modified RF signal 224a to modify the impedance of modified RF signal 224a and output modified RF signal 224d.

[0059] 3 is a diagram of an embodiment of a system 300 illustrating an impedance matching unit 302 having a binary divider network 304. The system 300 includes the processor system 110, the RF generator 106, the impedance matching unit 302, and the plasma chamber 108.

[0060] The binary divider network 304 includes switches SWa, SWb, SWc, SWd, SWe, SWf, through SWn and capacitors C1, C2, C3, C4, C5, C6, through Cn, where n is a positive integer. As an example, each successive capacitor C1 through Cn has twice the capacitance of the preceding capacitor. For example, capacitor C1 has a capacitance of 8 picofarads (pF), capacitor C2 has a capacitance of 16 pF, capacitor C3 has a capacitance of 32 pF, capacitor C4 has a capacitance of 64 pF, capacitor C5 has a capacitance of 128 pF, capacitor C6 has a capacitance of 256 pF, and capacitor Cn has a capacitance of 512 pF. Each of C1 through Cn also represents the capacitance of the respective capacitor. For example, Cn is the capacitance of capacitor Cn.

[0061] The RF generator 106 is coupled to an input port 305 of the impedance matching unit 302 via an RF cable 116. The input port 305 is coupled to an output port 308 of the impedance matching unit 302 via an RF line 306. The output port 308 is coupled to an electrode of the plasma chamber 108 via an RF strap 142.

[0062] Capacitors C1 to Cn are coupled to the RF line 306 to form a shunt circuit. For example, capacitor C1 is coupled to a node N1 on the RF line 306, capacitor C2 is coupled to a node N2 on the RF line 306, capacitor C3 is coupled to a node N3 on the RF line 306, capacitor C4 is coupled to a node N4 on the RF line 306, capacitor C5 is coupled to a node N5 on the RF line 306, capacitor C6 is coupled to a node N6 on the RF line 306, and capacitor Cn is coupled to a node Nn on the RF line 306. Furthermore, each of capacitors C1 to Cn is coupled to a respective terminal of switches SW1 to SWn. For example, capacitor C1 is coupled to a first terminal of switch SW1, and capacitor Cn is coupled to a first terminal of switch Sn. Second terminals of switches SW1 to SWn are coupled to ground potential.

[0063] The input port 305 is coupled to the output port 308 via nodes N1-Nn. The processor system 110 is also coupled to switches SW1-SWn via their respective switch connections. For example, the processor system 110 is coupled to switch SWa via switch connection CSWa, to switch SWb via switch connection CSWb, to switch SWc via switch connection CSWc, to switch SWd via switch connection CSWd, to switch SWe via switch connection CSWe, to switch SWf via switch connection CSWf, and to switch SWn via switch connection CSWn.

[0064] The processor system 110 controls one or more of the switches SW1-SWn to an open or closed state via one or more of the switch connections CSWa-CSWn, respectively, in the same manner that the processor system 110 controls one or more of the switches SWa and SWb (FIG. 2A). When one or more of the switches SW1-SWn are closed, the respective capacitance of one or more of the capacitors C1-Cn coupled to the closed switch modifies the impedance of the RF signal 144 and outputs the modified RF signal 310 at the output port 308. One or more of the capacitors C1-Cn coupled to the closed switch acts as a shunt capacitor. Additionally, the remaining capacitors C1-Cn coupled to the remaining switches SW1-SWn that are open do not modify the impedance of the RF signal 144. By controlling the switches SW1-SWn, a capacitance between capacitance C1 and capacitance (2Cn-C1) is applied to modify the impedance of the RF signal 144 and output the modified RF signal 310.

[0065] The modified RF signal 310 is transmitted from the output port 308 through the RF strap 142 to an electrode of the plasma chamber 108. When one or more process gases are supplied to the plasma chamber 108 in addition to the modified RF signal 310, a plasma is generated or maintained in the plasma chamber 108 to process a substrate. It should be noted that by modifying the number of capacitors C1-Cn used as a shunt circuit, the combined capacitance applied by the capacitors C1-Cn can be fine-tuned.

[0066] 4 is a diagram of an embodiment of a plasma system 400 illustrating control of one or more reactive elements of an impedance matching unit 402 based on feedback from one or more sensors. The plasma system 400 includes an RF generator 106, an impedance matching unit 402, and a plasma chamber 108. The plasma system 400 further includes a host computer 104.

[0067] The plasma chamber 108 includes an upper electrode 404 and a substrate support 406. An example of a substrate support is an electrostatic chuck (ESC). The substrate support 406 includes a lower electrode 408 embedded therein. Each of the upper electrode 404 and the lower electrode 408 is fabricated from a metal such as aluminum or an aluminum alloy. A substrate S, such as a semiconductor wafer, is placed on the upper surface of the substrate support 406 for processing. A gap 410 exists between the upper electrode 404 and the substrate support 406.

[0068] Examples of the impedance matching unit 402 include the impedance matching unit 102 (FIG. 1A), the impedance matching unit 202 (FIG. 2A), and the impedance matching unit 302 (FIG. 3). Illustratively, the impedance matching unit 402 is the impedance matching unit 102, 202, or 302. The sensors of the plasma system 400 include an optical sensor 412 and a parameter sensor 414. Examples of the parameter sensor 414 include a complex voltage and current (VI) sensor, a voltage (V) sensor, and a current (I) sensor. An example of the optical sensor 412 is a spectrometer. Illustratively, the optical sensor 412 senses light emitted from the plasma generated in the gap 410 and outputs an electrical signal based on the wavelength of the light. The optical sensor 412 has a field of view directed toward the gap 410.

[0069] The parameter sensor 414 is coupled to a point 416 on the RF strap 142. The point 416 is between an output 418 of the impedance matching unit 402 and an input 420 of the plasma chamber 108. Examples of the output 418 include output port 140 (FIG. 1A), output port 222 (FIG. 2A), and output port 308 (FIG. 3).

[0070] The processor system 110 is coupled to the impedance matching unit 402 via a switch connection 432. Examples of the switch connection 432 include switch connections CSW1 and CSW2 (FIG. 1A), or switch connections CSWa and CSWb (FIG. 2A), or switch connections CSWa through CSWn (FIG. 3).

[0071] The impedance matching unit 402 receives the RF signal 144 at its input 422, matches the impedance of a load coupled to the output 418 with the impedance of a source coupled to the input 422, and outputs a modified RF signal 424 at the output 418. Examples of the input 422 include the input port 118 (FIG. 1A), the input port 204 (FIG. 2A), and the input port 305 (FIG. 3). Examples of a load coupled to the output 418 include the RF strap 142 and the plasma chamber 108. Examples of a source coupled to the input 422 include the RF cable 116 and the RF generator 106.

[0072] When one or more process gases are supplied to the gap 410 along with the modified RF signal 424 and a plasma is generated in the gap 410 to process the substrate S, the optical sensor 412 measures a parameter, such as one or more wavelengths of light output from the plasma, to generate a measurement signal 426 and transmits the measurement signal 426 to the processor system 110. The measurement signal 426 includes one or more measured values ​​of the parameter. Further, the parameter sensor 414 measures a parameter, such as a complex voltage and current, a complex voltage, or a complex current, and outputs a measurement signal 428 and a sensor measurement signal 428 to the processor system 110. The measurement signal 428 includes one or more measured values ​​of the parameter.

[0073] The processor system 110 receives the measurement signals 426 and 428 and determines whether the plasma is stable based on one or more of the measurement signals 426 and 428. For example, the processor system 110 compares the parameter measurements received in the measurement signals 426 or 428 with a predetermined parameter range, such as Range 2, to determine whether the measurements are within the predetermined parameter range. In this example, if the processor system 110 determines that the measurements are not within the predetermined parameter range but are within Range 1 or Range 3, the processor system 110 determines that the plasma is unstable and controls, such as by opening or closing one or more of the switches in the impedance matching unit 402, one or more reactances of one or more reactive elements in the impedance matching unit 402 to further modify the impedance of the RF signal 144 and output a modified RF signal 430. Further, in this example, the processor system 110 continues to control one or more reactive elements in the impedance matching unit 402 until the parameter measurements determine that the measurements are within the predetermined parameter range. Also, in this example, if the measured value is determined to be within the predetermined parameter range, the processor system 110 determines that the plasma is stable or has stability and does not further control the reactive element of the impedance matching unit 402. If the measured value is within the predetermined parameter range, a modified RF signal 430 is provided by the impedance matching unit 402 at output 418. When one or more process gases are supplied to the gap 410 with the modified RF signal 430, the substrate S is processed by the plasma in the gap 410. Further, in this example, the plasma is unstable or has instability if the measured value is outside the predetermined parameter range, e.g., within range 1 or range 3. Note that in this example, ranges 1 and 3 correspond to states in which the plasma is unstable, and range 2 corresponds to a state in which the plasma is stable.An example of an indication of a stable plasma is uniformity in the impedance of the plasma across the top surface of the substrate S, which results in a uniform process rate, such as an etch rate or a deposition rate, across the top surface. An example of an indication of an unstable plasma is a lack of uniformity.

[0074] It should be noted that when the plasma is unstable, it is outside the predetermined stability range, and when the plasma is stable, it is within the predetermined stability range.

[0075] Examples of the reactance elements of the impedance matching unit 402 include reactance elements X1 and X2 (FIG. 1A), reactance elements Xa and Xb (FIG. 2A), or capacitors C1 to Cn (FIG. 3). Examples of the switches of the impedance matching unit 402 include switches SW1 and SW2 (FIG. 1A), switches SWa and SWb (FIG. 2A), or switches SWa to SWn (FIG. 3). Examples of the modified RF signal 430 include modified RF signal 146A, 146B, 146C, or 146D (FIG. 1A), 224a, 224b, 224c, or 224d (FIG. 2A), or 310 (FIG. 3).

[0076] In one embodiment, plasma system 400 includes one or more additional sensors, such as a VI sensor, a V sensor, or an I sensor, and processor system 110 controls impedance matching unit 402 based on one or more measurement signals received from the one or more additional sensors instead of or in addition to controlling impedance matching unit 402 based on one or more of measurement signals 426 and 428. For example, the one or more additional sensors are coupled to RF cable 116 and processor system 110.

[0077] In one embodiment, the parameter sensor 414 is coupled to the output 418 or the input 420 .

[0078] In one embodiment, the plasma system 400 does not include a parameter sensor 414 or an optical sensor 412 .

[0079] FIG. 5 is a diagram of an embodiment of a plasma system 500 illustrating control of the reactance of a reactive element of the impedance matching unit 402 based on a change in the state of a variable, such as the power, frequency, or voltage of the RF signal 144. An example of a variable state is a variable level, such as a power level, frequency level, or voltage level. The variable level includes a statistical value, such as the mean or median, of multiple values ​​of the variable. For example, a first variable level has a first statistical value, and a second variable level has a second statistical value. The first statistical value is different from the second statistical value and is either greater than or less than the second statistical value. For example, the minimum value of the first multiple values ​​from which the first statistical value is generated is greater than the maximum value of the second multiple values ​​from which the second statistical value is generated. In this example, the first statistical value is greater than the second statistical value.

[0080] Plasma system 500 is similar to plasma system 400, except that in plasma system 500, processor system 110 dynamically controls impedance matching unit 402 based on changes in the state of the variable. Processor system 110 receives measurement signals 426 and 428 and determines whether to modify the state of the variable, modify the reactance of impedance matching unit 402, or a combination thereof, based on one or more of measurement signals 426 and 428. For example, during a period when a state S of the variable of RF signal 144 is output from RF generator 106, processor system 110 determines that the measured value of the parameter received in measurement signal 426 or 428 is not within a predetermined parameter range, such as not within range 2 (FIG. 4), where m is at least 0. In this example, upon determining that the measured value of the parameter received in measurement signal 426 or 428 is not within the predetermined parameter range, processor system 110 determines to modify state S of RF signal 144 to another state S(m±p), where p is a positive integer. Further, in this example, upon determining to modify state Sm, processor system 110 transmits state modification signal 502 to RF generator 106 via transmission cable 114. Upon receiving state modification signal 502, RF generator 106 changes state Sm of RF signal 144 to state S(m±p). Further, in this example, within a predetermined time period from the time state modification signal 502 is transmitted or simultaneously with the time state modification signal 502 is transmitted, processor system 110 receives measurements in measurement signals 426 or 428, determines that the measured values ​​of the parameters received in measurement signals 426 or 428 are not within the predetermined parameter ranges, and transmits one or more control signals 504, e.g., one or more on control signals or one or more off control signals or a combination thereof, to impedance matching unit 402 via one or more of switch connections 432, respectively.

[0081] In this example, one or more control signals 504 are sent to control one or more of the switches of the impedance matching unit 402 to modify the reactance of the impedance matching unit 402. For example, the processor system 110 sends an ON control signal to switch SW1 to close it and an OFF control signal to switch SW2 to open it (FIG. 1A). As another example, the processor system 110 sends an ON control signal to switch SWa to close it and an ON control signal to switch SWb to close it (FIG. 2A). As yet another example, the processor system 110 sends ON control signals to switches SWa-SWd to close them and OFF control signals to switches SWe-SWn to open them (FIG. 3). In this example, the processor system 110 continues to modify the state of the RF signal 144, the reactance of the impedance matching unit 402, or a combination thereof, until the measured parameter falls within a predetermined parameter range. Further, in this example, upon determining that the measured parameter value is within the predetermined parameter range, the processor system 110 maintains the state of the RF signal 144 and the reactance of the impedance matching unit 402 such that the measured parameter value is within the predetermined parameter range.

[0082] When the state Sm of the RF signal 144 is modified or the reactance of the impedance matching unit 402 is modified until the measured parameter falls within a predetermined parameter range, the impedance of the RF signal 144 is modified, and the RF generator 106 outputs a modified RF signal 430 at the output 418. By dynamically modifying the state of the RF generator 106 based on the measured parameter of the measurement signal 426 or 428, the RF generator 106 generates an RF signal 144 having a different number of states during each cycle of the clock signal. For example, the RF signal 144 has four states during the first cycle of the clock signal and five states during the second cycle of the clock signal. As another example, the RF signal 144 has three states during the first cycle and seven states during the second cycle. The clock signal is generated by the processor system 110 and transmitted to the RF generator 106 via the transmission cable 114.

[0083] FIG. 6 is a diagram of an embodiment of a plasma system 600 illustrating control of the impedance matching unit 402 based on states identified within a recipe for the RF signal 144. The plasma system 600 is similar to the plasma system 500 (FIG. 5), except that the plasma system 600 does not include the parameter sensor 414 and the optical sensor 412 (FIG. 5). The processor system 110 generates a recipe signal 602 and transmits the recipe signal 602 to the RF generator 106 via the transfer cable 114. The recipe signal 602 includes multiple states of a variable of the RF signal 144 and includes instructions to repeat the same multiple states during each cycle of the clock signal. For example, the recipe signal 602 includes multiple power levels of the RF signal 144. Upon receiving the recipe signal 602, the RF generator 106 generates the RF signal 144 having multiple states during each cycle of the clock signal.

[0084] For each state of the RF signal 144 output from the RF generator 106, the processor system 110 controls the impedance matching unit 402 to achieve a reactance for the state and outputs the modified RF signal 430. For example, during a period when the RF signal 144 has a state Sm, the processor system 110 controls the impedance matching unit 402 to achieve a first reactance corresponding to the state Sm, and during a period when the RF signal 144 has another state S(m+p), the processor system 110 controls the impedance matching unit 402 to achieve a second reactance corresponding to the state S(m+p). In this example, the first reactance is different from the second reactance, e.g., greater than or less than the second reactance. Furthermore, in this example, the switches of the impedance matching unit 402 are controlled by the processor system 110 in different manners to achieve each of the different reactances. Illustratively, to achieve a first reactance, the processor system 110 sends a first set of control signals to switches SW1 and SW2 of the impedance matching unit 410 to open switch SW1 and close switch SW2. Further illustratively, the processor system 110 sends a second set of control signals to switches SW1 and SW2 of the impedance matching unit 410 to close switch SW1 and open switch SW2 to achieve a second reactance. Also in this example, a correspondence, e.g., a one-to-one or unique correspondence, between the state of the RF signal 144, the reactance of the impedance matching unit 402, and the switch positions to achieve the reactance is stored in the memory device 112 of the host computer 104 for access by the processor system 110. Illustrative switch positions include an open position and a closed position.

[0085] As another example, during a first period in which the RF generator 106 is controlled to transition the RF signal 144 from the previous state S(m−1) to state S, the processor system 110 controls the impedance matching unit 402 to modify the first reactance corresponding to state S(m−1) to a second reactance corresponding to state S. In this example, both state S and the second reactance are achieved simultaneously by dynamically controlling the RF generator 106 and the impedance matching unit 402 during the first period in real time. Furthermore, in this example, during a second period in which the RF generator 106 is controlled to transition the RF signal 144 from state S to state S(m+1), the processor system 110 controls the impedance matching unit 402 to modify the second reactance corresponding to state S to a third reactance corresponding to state S(m+1). In this example, both state S(m+1) and the third reactance are achieved simultaneously by dynamically controlling the RF generator 106 and the impedance matching unit 402 during the second time period in real time.

[0086] As yet another example, at a first time when the RF generator 106 is controlled to transition the RF signal 144 from the previous state S(m−1) to state S, the processor system 110 controls the impedance matching unit 402 to modify the first reactance corresponding to state S(m−1) to a second reactance corresponding to state S. In this example, both state S and the second reactance are achieved simultaneously by dynamically controlling the RF generator 106 and the impedance matching unit 402 in real time at the first time. Furthermore, in this example, at a second time when the RF generator 106 is controlled to transition the RF signal 144 from state S to state S(m+1), the processor system 110 controls the impedance matching unit 402 to modify the second reactance corresponding to state S to a third reactance corresponding to state S(m+1). In this example, both state S(m+1) and the third reactance are achieved simultaneously by dynamically controlling the RF generator 106 and the impedance matching unit 402 at a second time in real time.

[0087] By dynamically controlling the reactance of the impedance matching unit 402 in real time in response to changes in the state of the RF signal 144, the likelihood of plasma instability occurring is reduced. For example, if a parameter sensor such as parameter sensor 414 (FIG. 5) is used in the plasma system 600, the impedance matching unit 402 is controlled immediately, such as during a transition period of the RF signal 144, or simultaneously with controlling the RF generator 106 to change the state of the RF signal 144, prior to detecting the onset of instability. In this example, controlling the impedance matching unit 402 in this manner reduces changes in the onset of instability.

[0088] In one embodiment, no parameter sensors are used in the plasma system 600 .

[0089] 7A is a diagram of one embodiment of a table 700 illustrating a correspondence between the reactance of impedance matching unit 402 ( FIG. 6 ), the positions of switches SW1 and SW2, and the states S1, S2, S3, and S4 of RF signal 144 of FIG. 6 . This correspondence is stored in memory device 112 ( FIG. 6 ). For example, memory device 112 includes correspondence 702 indicating that during state S1 of RF signal 144, switch SW1 should be open and switch SW2 should be open to apply the combined reactance of reactances X1 and X2 to the impedance of RF signal 144. In this example, memory device 112 includes correspondence 704 indicating that during state S2 of RF signal 144, switch SW1 should be closed and switch SW2 should be open to apply reactance X2 to the impedance of RF signal 144. Additionally, in this example, memory device 112 includes correspondence 706 indicating that during state S3 of RF signal 144, switch SW2 should be closed and switch SW1 should be open to apply reactance X1 to the impedance of RF signal 144. In this example, memory device 112 includes correspondence 708 indicating that during state S4 of RF signal 144, switch SW1 should be closed and switch SW2 should be closed to not apply reactances X1 and X2 to the impedance of RF signal 144. When reactances X1 and X2 are not applied to RF signal 144, the impedance of RF signal 144 is not substantially modified.

[0090] The processor system 110 accesses one of the correspondences 702-708 from the table 700 and determines the positions of the switches SW1 and SW2 based on the reactance applied to the impedance of the RF signal 144. The reactance is identified by the processor system 110 based on one of the states S1-S4 of the RF signal 144. The processor system 110 controls the switches SW1 and SW2 to achieve a position that further achieves the identified reactance during the state of the RF signal 144.

[0091] 7B is a diagram of one embodiment of a table 750 illustrating a correspondence between the reactances of the impedance matching unit 402 (FIG. 6), the positions of the switches SWa and SWb, and the states S1, S2, S3, and S4 of the RF signal 144 of FIG. 6. This correspondence is stored in the memory device 112 (FIG. 6). For example, the memory device 112 includes a correspondence 752 indicating that during the state S1 of the RF signal 144, the switch SWa should be open and the switch SWb should be open to prevent the reactances Xa and Xb from being applied to the impedance of the RF signal 144. When the reactances Xa and Xb are not applied to the impedance of the RF signal 144, the impedance of the RF signal 144 is not substantially modified. In this example, the memory device 112 includes a correspondence 754 indicating that during the state S2 of the RF signal 144, the switch SWa should be open and the switch SWb should be closed to apply the reactance Xb to the impedance of the RF signal 144. Additionally, in this example, memory device 112 includes correspondence 756 indicating that during state S3 of RF signal 144, switch SWa should be closed and switch SWb should be open to apply reactance Xa to the impedance of RF signal 144. In this example, memory device 112 includes correspondence 758 indicating that during state S4 of RF signal 144, switch SWa should be closed and switch SW2 should be closed to apply the combined reactance of reactances Xa and Xb to the impedance of RF signal 144.

[0092] The processor system 110 accesses one of the correspondences 752-758 from the table 750 and determines the positions of the switches SWa and SWb based on the reactance applied to the impedance of the RF signal 144. The reactance is identified by the processor system 110 based on one of the states S1-S4 of the RF signal 144. The processor system 110 controls the switches SWa and SWb to achieve a position that further achieves the identified reactance during each state of the RF signal 144.

[0093] Broadly, in various embodiments, a controller is defined as an electronic device having various integrated circuits, logic, memory, and / or software that receives instructions, issues instructions, controls operations, enables cleaning operations, enables endpoint measurements, etc. Integrated circuits include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as ASICs, PLDs, and / or one or more microprocessors, i.e., microcontrollers, that execute program instructions (e.g., software). Program instructions are instructions communicated to the controller in the form of various individual settings (or program files) that define parameters, coefficients, variables, etc., for performing a particular process on or for a semiconductor wafer or system. Program instructions, in some embodiments, are part of a recipe defined by a process engineer to implement one or more processing steps in the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or wafer dies.

[0094] In various embodiments, exemplary systems to which the methods are applied include, but are not limited to, a plasma etch chamber or module, a deposition chamber or module, a spin rinse chamber or module, a metal plating chamber or module, a cleaning chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a tracking chamber or module, and any other semiconductor processing system associated with or used in the fabrication and / or manufacturing of semiconductor wafers.

[0095] It is further noted that in some embodiments, the operations described above apply to several types of plasma chambers, such as plasma chambers including inductively coupled plasma (ICP) reactors, transformer-coupled plasma chambers, conductor tools, dielectric tools, and electron cyclotron resonance (ECR) reactors. For example, one or more RF generators are coupled to an inductor in an ICP reactor. Examples of inductor shapes include a solenoid, a dome-shaped coil, a flat coil, and the like.

[0096] Some of the embodiments also relate to hardware units or apparatus for performing these operations. The apparatus is specially constructed for use as a special purpose computer. When defined as a special purpose computer, the computer is operable for its dedicated purpose, while also performing other processes, program execution, or routines that are not part of its dedicated purpose.

[0097] One or more embodiments may also be fabricated as computer-readable code on a non-transitory computer-readable medium. The non-transitory computer-readable medium is any data storage hardware unit (e.g., a memory device, etc.) that stores data, which is then read by a computer system. Examples of non-transitory computer-readable media include hard drives, network-attached storage (NAS), ROM, RAM, compact disc ROM (CD-ROM), CD-recordable (CD-R), CD-rewritable (CD-RW), magnetic tape, and other optical and non-optical data storage hardware units. In some embodiments, the non-transitory computer-readable medium comprises a computer-readable tangible medium distributed over a network-coupled computer system so that the computer-readable code is stored and executed in a distributed manner.

[0098] Although the method operations above have been described in a particular order, it should be understood that in various embodiments, other housekeeping operations are performed between each operation, or each method operation is coordinated to occur at slightly different times, or is distributed across a system that allows each method operation to occur at various intervals, or is performed in an order other than that set forth above.

[0099] It is further noted that in one embodiment, one or more features of any of the above-described embodiments may be combined with one or more features of any other of the above-described embodiments without departing from the scope described in the various embodiments described in this disclosure.

[0100] Although the foregoing embodiments have been described in some detail for clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. The present embodiments are therefore to be considered illustrative rather than restrictive, and the embodiments should not be limited to the details set forth herein.

Claims

1. An impedance matching unit, an input port configured to be coupled to a radio frequency (RF) generator; an output port configured to be coupled to a plasma chamber; a connection point located between the input port and the output port; a first reactive element coupled between the input port and the connection point; a first switch coupled in parallel to the first reactive element; a second reactance element coupled between the node and the output port; a second switch coupled in parallel to the second reactance element; An impedance matching unit comprising:

2. 2. The impedance matching unit according to claim 1, An impedance matching unit configured to control the first switch or the second switch or a combination thereof based on changes in stability of plasma in the plasma chamber.

3. 2. The impedance matching unit according to claim 1, An impedance matching unit, wherein the first switch is configured to be in a first position or a second position, the second switch is configured to be in a first position or a second position, the first switch is configured to switch from the first position to the second position when the stability is outside a predetermined range, and when the first switch is switched from the first position to the second position, the stability is corrected to be within the predetermined range.

4. 4. The impedance matching unit according to claim 3, an impedance matching unit, wherein the second switch is configured to switch from the first position to the second position when the stability is outside the predetermined range, and when the second switch switches from the first position to the second position, the stability is corrected to be within the predetermined range.

5. 2. The impedance matching unit according to claim 1, An impedance matching unit configured to control the first switch or the second switch or a combination thereof based on a change in state of an RF signal generated by the RF generator.

6. 6. An impedance matching unit according to claim 5, an impedance matching unit, wherein the first switch is configured to be in a first position or a second position, the second switch is configured to be in a first position or a second position, and the first switch is configured to switch from the first position to the second position when the state of the RF signal changes from a first state to a second state.

7. 7. An impedance matching unit according to claim 6, The second switch is configured to switch from the first position to the second position when the state of the RF signal changes from the first state to the second state.

8. 6. An impedance matching unit according to claim 5, The state is determined based on a signal received from a sensor, the impedance matching unit.

9. 6. An impedance matching unit according to claim 5, The state is received in a recipe. An impedance matching unit.

10. 2. The impedance matching unit according to claim 1, An impedance matching unit, wherein the first reactive element is a capacitor or an inductor, and the second reactive element is a capacitor or an inductor.

11. An impedance matching unit, an input port configured to be coupled to a radio frequency (RF) generator; an output port configured to be coupled to a plasma chamber; a first connection point located between the input port and the output port; a second connection point located between the input port and the output port; a first reactive element coupled to the first node; a first switch coupled in series with the first reactance element, the first switch being coupled to a ground potential; a second reactive element coupled to the second node; a second switch coupled in series with the second reactance element, the second switch being coupled to the ground potential; An impedance matching unit comprising:

12. 12. An impedance matching unit according to claim 11, An impedance matching unit configured to control the first switch or the second switch or a combination thereof based on changes in stability of plasma in the plasma chamber.

13. 12. An impedance matching unit according to claim 11, An impedance matching unit, wherein the first switch is configured to be in a first position or a second position, the second switch is configured to be in a first position or a second position, the first switch is configured to switch from the first position to the second position when the stability is outside a predetermined range, and when the first switch is switched from the first position to the second position, the stability is corrected to be within the predetermined range.

14. 14. An impedance matching unit according to claim 13, comprising: an impedance matching unit, wherein the second switch is configured to switch from the first position to the second position when the stability is outside the predetermined range, and when the second switch switches from the first position to the second position, the stability is corrected to be within the predetermined range.

15. 12. An impedance matching unit according to claim 11, An impedance matching unit configured to control the first switch or the second switch or a combination thereof based on a change in state of an RF signal generated by the RF generator.

16. 16. An impedance matching unit according to claim 15, comprising: an impedance matching unit, wherein the first switch is configured to be in a first position or a second position, the second switch is configured to be in a first position or a second position, and the first switch is configured to switch from the first position to the second position when the state of the RF signal changes from a first state to a second state.

17. 17. An impedance matching unit according to claim 16, comprising: The second switch is configured to switch from the first position to the second position when the state of the RF signal changes from the first state to the second state.

18. 16. The method of claim 15, The method wherein the state is determined based on a signal received from a sensor.

19. 16. An impedance matching unit according to claim 15, comprising: The state is determined based on a recipe. An impedance matching unit.

20. 12. An impedance matching unit according to claim 11, An impedance matching unit, wherein the first reactive element is a capacitor or an inductor, and the second reactive element is a capacitor or an inductor.

21. receiving a measurement of a parameter indicative of the stability of a plasma in the plasma chamber; determining a plurality of positions of a plurality of switches in an impedance matching unit based on the measured values ​​of the parameters, the impedance matching unit being located between a radio frequency (RF) generator and a plasma chamber, and each of the plurality of switches being in parallel with a corresponding one of a plurality of reactive elements of the impedance matching unit; controlling the plurality of switches to the plurality of positions to achieve stability of the plasma; A method comprising:

22. 22. The method of claim 21, The method, wherein the plurality of reactive elements are a plurality of capacitors or a plurality of inductors or a combination thereof.

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