System and method for compensating for RF power loss

Abstract

SOLUTION: Systems and methods for compensating for radio frequency (RF) power loss are disclosed. One of the methods includes conducting a no plasma test to determine resistance associated with output of an impedance matching circuit. After conducting the no plasma test, a substrate is processed in a plasma chamber. During processing of the substrate, power loss associated with the output of the impedance matching circuit is determined. The power loss is used to determine an amount of power to be delivered by a RF generator. The amount of power delivered is adjusted until the power loss is stabilized. The stabilization of the power loss facilitates uniform process of the substrate and additional substrates in the plasma chamber.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present embodiments relate to a system and method for compensating for radio frequency (RF) power losses. [Background technology]

[0002] The description of the background art provided herein is intended to provide a general background to the present disclosure, and the work of the inventors named herein, to the extent described in this background art, together with aspects of the description that would not ordinarily be considered prior art at the time of filing, are not admitted, expressly or impliedly, as prior art to the present disclosure.

[0003] The wafer is etched using a plasma tool that includes a radio frequency (RF) generator, a matching network or matcher, and a plasma chamber. The RF generator is connected to the matcher via a coaxial cable, and the matcher is connected to the plasma chamber via a transmission line. The wafer is placed in the plasma chamber.

[0004] Once the wafer is positioned, the RF generator is turned on to provide RF power to the plasma chamber through a matcher and a transmission line, and a process gas is supplied to the plasma chamber. When the process gas is ignited by the RF power, a plasma is ignited in the plasma chamber. The plasma is used to etch the wafer.

[0005] It is against this background that the embodiments described in this disclosure arise. Summary of the Invention

[0006] The embodiments of the present disclosure provide a system, an apparatus, a method, and a computer program for compensating for radio frequency (RF) power loss. It should be understood that the embodiments can be embodied in various forms, such as a process, an apparatus, a system, hardware, or a method recorded on a computer readable medium. Some embodiments are described below.

[0007] Some semiconductor processing tools (such as conductor etch (CE) tools) perform subsystem biasing in a voltage control mode and some in a power control mode. The voltage control mode does not utilize power compensation operation. In the power control mode, chamber-to-chamber differences in parasitic power losses create variations in the power coupled to the plasma load. To provide optimal chamber matching performance, the variations in the coupled power are minimized.

[0008] The systems and methods described herein provide a compensation method to achieve corrective action to reduce variations in coupled power between chambers. The systems and methods relate to a chamber matching power compensation scheme for a bias subsystem. The compensation scheme is applied to a bias subsystem operating in a power control mode. The compensation scheme utilizes a current probe located at the output of a bias matching network. Current measurements received from the current probe allow for a real-time calculation of parasitic power losses from the bias matching network to the plasma or are used to compensate for the power losses. These parasitic power losses are removed using a modified control loop that continuously updates the power set point of the RF generator. The corrective action provides an offset to the power set point equal to the parasitic power losses along the RF delivery path in real-time.

[0009] In some embodiments, a two-step procedure is implemented to account for parasitic power losses in the bias matching network and RF supply assembly. The procedure utilizes a probe (such as a current probe, a voltage-current probe, an impedance measurement probe, or an impedance scanning probe) that is placed at the output of the bias matching network. First, the root mean square (RMS) current is measured by the probe during a no-plasma test (NPT). The equivalent series resistance (ESR) value of the bias matching network and the entire assembly is calculated by performing a linear regression on the square of the measured RMS current and the power delivered by the RF generator. The ESR value is stored by the host computer and utilized as a system constant.

[0010] Second, a control algorithm is implemented to provide real-time corrective action to the recipe power setpoint (e.g., P_sp_rec) of the RF generator using the ESR value measured above. When a recipe step is being executed, the power loss (e.g., P_loss) can be calculated at each time increment or time step i using the following formula: P_loss(i)=ERS*(I_RMS(i)) 2 (1) where I_RMS(i) is the RMS current read by the probe at time increment i. The power loss for the current time step is carried forward and added to the RF generator recipe power setpoint P_sp_rec to determine an updated generator power setpoint (e.g., P_sp_gen), where "sp" represents the setpoint and "gen" represents the RF generator. The following equation shows the updated generator power setpoint at that time increment: P_sp_gen(i)=P_sp_rec+P_loss(i-1)...(2) The procedure is repeated until the correction offset P_loss(i) is equal to the measured loss P_loss(i-1), at which point the parasitic power losses are taken into account.

[0011] Some advantages of the systems and methods described herein for compensating for RF power losses (e.g., parasitic power losses) include achieving chamber repeatability when processing one or more substrates. An RF generator provides RF power to an electrode in a plasma chamber. The RF power is transmitted from the RF generator to the electrode via an RF path. Due to characteristics of components in the RF path, some RF power is lost on the RF path. Examples of components include an RF cable, an impedance matching circuit, and an RF transmission line. The RF cable connects the RF generator to an impedance matching circuit (e.g., a bias matching network). And, the RF transmission line connects the impedance matching circuit to the plasma chamber. The power delivered by the RF generator is adjusted to account for RF power losses in the RF path. The power delivered by the RF generator is adjusted until the RF power losses are stable. After the RF power losses are stable, the RF generator is controlled to deliver the same or substantially the same amount of delivered power. When the same or substantially the same amount of power is delivered by the RF generator, one or more substrates are processed uniformly. For example, a uniform etch rate or a uniform deposition rate may be achieved when processing multiple substrates. As another example, the substrates may be desirably processed to achieve a uniform etch rate or a uniform deposition rate.

[0012] Other aspects will become apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0013] The embodiments are understood by reference to the following description taken in conjunction with the accompanying drawings.

[0014] [Figure 1] FIG. 1 illustrates one embodiment of a system to illustrate a plasma-free test performed prior to processing a substrate.

[0015] [Diagram 2] FIG. 2 illustrates one embodiment of a graph to illustrate the determination of a resistance (eg, equivalent series resistance (ESR)) associated with the output of an impedance matching circuit.

[0016] [Diagram 3] FIG. 1 illustrates one embodiment of a system to illustrate the use of resistance in determining the amount of power generated and delivered by a radio frequency (RF) generator to account for power losses associated with impedance matching circuits and transmission lines.

[0017] [Figure 4] FIG. 13 illustrates one embodiment of a table to illustrate how, during processing of a substrate, a processor continues to modify the amount of power delivered by the RF generator based on the amount of power loss associated with the output of the impedance matching circuit.

[0018] [Diagram 5] FIG. 2 shows an embodiment of a graph to illustrate how the power delivered by an RF generator varies taking into account the loss of power delivered at the output of an impedance matching circuit.

[0019] [Figure 6] FIG. 1 illustrates an embodiment of a system to illustrate an application of a method for compensating for loss of transmitted power.

[0020] [Figure 7] FIG. 5 illustrates one embodiment of a system to illustrate that the amount of delivered power determined by applying the method described with respect to FIG. 4 is maintained for processing another substrate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The following embodiments describe systems and methods for compensating for radio frequency (RF) power loss. It will be apparent that the embodiments may be practiced without some or all of these specific details. Additionally, detailed descriptions of well-known process operations have been omitted in order to avoid unnecessarily obscuring the embodiments.

[0022] 1 illustrates an embodiment of a system 100 for illustrating a plasma-free test performed prior to processing a substrate. The system 100 includes several components, such as an RF generator 102, an impedance matching circuit 104, a current sensor 106, a plasma chamber 108, and a host computing device 110.

[0023] Examples of the RF generator 102 include a kilohertz (kHz) RF generator or a megahertz (MHz) RF generator. An example of a kHz RF generator is an RF generator with an operating frequency of 400 kHz. Examples of a MHz RF generator include an RF generator with an operating frequency of a 1 MHz RF generator or a 2 MHz RF generator or a 13.56 MHz RF generator or a 27 MHz RF generator or a 60 MHz RF generator. The RF generator 102 includes a processor, such as a digital signal processor (DSP), a driver / amplifier circuit, and an RF power supply. The processor is connected to the driver / amplifier circuit, which is connected to the RF power supply. An example of an RF power supply includes an RF oscillator.

[0024] Examples of impedance matching circuit 104 include circuits having a network of circuit components connected in series or parallel to each other. Examples of circuit components include resistors, inductors, and capacitors. For example, a circuit component may be a shunt capacitor or a series capacitor.

[0025] The plasma chamber 108 is a parallel plate plasma chamber (e.g., a capacitively coupled plasma (CCP) chamber). The plasma chamber 108 includes a chuck 112 and an upper electrode 114 facing the chuck 112. An example of the chuck 112 includes an electrostatic chuck (ESC) that includes a lower electrode and a ceramic plate disposed on top of the lower electrode. Each of the chuck 112 and the upper electrode 114 is formed from a metal, such as aluminum or an aluminum alloy. The upper electrode 114 is connected to a ground potential.

[0026] Examples of the current sensor 106 include a voltage-current (VI) probe or a current probe or an impedance sensor or an impedance scanner or an impedance probe. Examples of the host computing device 110 include a computer and a server. The computer may be a desktop computer or a laptop computer or a smartphone or a tablet. The host computing device 110 includes a processor 120 and a memory device 122. Examples of processors used herein include a central processing unit (CPU), an application specific integrated circuit (ASIC), a programmable logic device (PLD), a controller, a microprocessor, and a microcontroller. Examples of memory devices include a random access memory (RAM) and a read only memory (ROM). For example, the memory device is a flash memory or a redundant array of independent disks (RAID). The memory device 122 is connected to the processor 120 via a connection such as a serial transfer connection, a parallel transfer connection, a bus, or a universal serial bus (USB) connection.

[0027] The RF generator 102 is connected to the impedance matching circuit via an RF cable 116. For example, an output O1 of the RF power supply of the RF generator 102 is connected to an input I2 of the impedance matching circuit 104 via the RF cable 116. The impedance matching circuit 104 is also connected to a lower electrode of the chuck 112 via an RF transmission line 118. For example, an output O2 of the impedance matching circuit 104 is connected to the lower electrode via the RF transmission line 118. The RF transmission line 118 is another example of a component of the plasma system 100, and includes an RF rod, an insulator, and a sleeve. The insulator encases the RF rod, and the sleeve forms a protective cover surrounding the insulator.

[0028] The processor 120 is connected to an input I1 of the RF generator 102 via a connecting cable 125, such as a serial transfer cable, a parallel transfer cable, an Ethernet cable, or a USB cable. For example, the processor 120 is connected to the processor of the RF generator 102 via the connecting cable 125. The current sensor 106 is connected to an output O2 of the impedance matching circuit 104 via an RF cable and is connected to the processor 120 via a connecting cable 121. Examples of connecting cables have been described above.

[0029] During a plasma-free test, no plasma is generated within the plasma chamber 108. For example, one or more process gases (such as a fluorine-containing gas or an oxygen-containing gas) are not supplied to the plasma chamber 108 to ignite a plasma within the plasma chamber 108. Also, in this example, no substrate is placed on an upper surface of the chuck 112 for processing.

[0030] The processor 120 provides a command signal having a quantity of one or more variables (such as frequency and transmitted power) to the RF generator 102 via the connecting cable 125 and the input I1. The transmitted power is the sum of the supplied power and the power loss occurring in the RF cable 116. The supplied power is the power generated by the RF generator 102 without receiving a command signal having the quantity of the transmitted power. For example, the supplied power is the power supplied at the output O1 by the RF generator 102 when the power loss in the RF cable 116 is not taken into account. The quantities of the variables are stored in the memory device 122 for access by the processor 120.

[0031] The RF generator 102 receives a command signal having a variable amount and generates an RF signal 124. For example, a processor of the RF generator 102 receives a command signal having a variable amount from the processor 120 and generates a signal having those amounts. The processor of the RF generator 102 provides the signal to a driver / amplifier circuit of the RF generator 102. A driver (e.g., one or more transistors) of the driver / amplifier circuit generates a current signal upon receiving the signal from the processor of the RF generator 102. The amplifier of the driver / amplifier circuit amplifies the power signal to output an amplified current signal and transmits the amplified current signal to an RF power supply of the RF generator 102. The RF power supply oscillates to generate an RF signal 124 having a variable amount. The RF signal 124 is provided by the RF generator 102 to the impedance matching circuit 104 via an output O1, an RF cable 116, and an input I2.

[0032] The impedance matching circuit 104 matches the impedance of a load connected to an output O2 of the impedance matching circuit 104 to the impedance of a source connected to an input I2 of the impedance matching circuit 104, and outputs a modulated RF signal 126 at the output O2. Examples of a load include an RF transmission line 118 and a plasma chamber 108. Examples of a source include an RF cable 116 and an RF generator 102.

[0033] The modulated RF signal 126 is transmitted to the lower electrode of the chuck 112 via RF transmission line 118. While the modulated RF signal 120 is provided or supplied at the output O2 during a plasma-free test, the current sensor 106 measures the amount of current (e.g., root mean square current (Irms)) being supplied at the output O2. Current is an example of a parameter. Each amount of current measured by the current sensor 106 is the root mean square (rms) of multiple amounts of current supplied at the output O2. The current sensor 106 provides a measurement of the amount of current (e.g., Irms) at the output O2 to the processor 120 via a connecting cable 121.

[0034] The processor 120 receives the measured value of the amount of current and generates a database (such as a table or list) containing a correspondence between the amount of current and the amount of delivered power at which the amount of current Irms was measured. For example, when the processor 120 controls the RF generator 102 to generate an RF signal 124 having a delivered power of an amount Pdel1, the current sensor 106 measures the amount of current Irms1 provided at the output O2. The delivered power is another example of a parameter. The processor 120 stores the correspondence (such as a one-to-one relationship, connection, association, or mapping) between the amounts Pdel1 and Irms1 in a database, which is stored in the memory device 122. Similarly, when the processor 120 controls the RF generator 102 to generate an RF signal 124 having a delivered power of another amount Pdel2, the power sensor 106 measures another amount Irms2 of current provided at the output O2 and provides the amount Irms2 to the processor 120 via the connecting cable 121. The processor 120 stores the correspondence between the quantities Pdel2 and Irms2 in a database. In this manner, multiple correspondences between the amount of power delivered in the RF signal 124 by the RF generator 102 and the amount of current measured at the output O2 over a period of time t are created or determined by the processor 120 and stored in a database.

[0035] It should be noted that the processor 120 calibrates the RF generator 102 to determine the amount of power P_del (P_del1, P_del2, etc.) delivered by the RF generator 102 at the output O1. For example, the RF generator 102 is connected to a dummy load, such as a 50 ohm load, via the RF cable 116, which is a load having a resistance of 50 ohms. The dummy load is also referred to herein as a known load. A measurement device (such as a voltage and current sensor or a power sensor) is connected to an input of the dummy load and is connected to the processor 120. The processor 120 generates a command signal to control the RF generator 120 to provide an RF signal at the output O1. Upon receiving the command signal, the RF generator 102 generates an RF signal and provides the RF signal to the dummy load via the output O1 and the RF cable 116. The measurement device measures the amount of power at the input of the dummy load. The amount of power measured at the input indicates the amount of power lost in the RF cable 116. The processor 120 receives the measured amount of power to determine the amount of power delivered by the RF generator 102 and determines a correspondence between the amount of power delivered by the RF generator 102 and the amount of power measured at the input of the dummy load. For example, the processor 120 determines a difference between the amount of power delivered by the RF generator 102 at the output O1 and the amount of power measured at the input of the dummy load. The difference is equal to the amount of power loss in the RF cable 116. The processor 120 adds the difference to the amount of power delivered by the RF generator 120 to calculate the amount of power delivered by the RF generator 120 (e.g., Pdel1). The processor 120 stores in a database a correspondence (e.g., one-to-one relationship, connection, association, or mapping) between the amount of power delivered by the RF generator 120 (e.g., Psup1) and the amount of power delivered by the RF generator 122 (e.g., Pdel1) to take into account the power loss in the RF cable 116. In this way, a database is created by the processor 120 having a number of amounts of delivered power (Pdel1, Pdel2, etc.) at output O1 and having a number of amounts of supplied power (Psup1, Psup2, etc.) at output O1.The database contains a correspondence between the amount of power provided by the RF generator 102 at output O1 and the amount of power delivered by the RF generator 102 at output O1.

[0036] It should be noted that since the power P_del delivered at the output O1 is calibrated to take into account power losses in the RF cable 116, the power P_del delivered at the output O1 of the RF generator 102 is sometimes referred to in this specification as the power delivered at the input I2 of the impedance matching circuit 104.

[0037] In one embodiment, the impedance matching circuit may also be referred to herein as a matcher, a matching network, an impedance matching network, or a matching housing, and these terms are used interchangeably herein.

[0038] In one embodiment, instead of the upper electrode 114 being connected to ground potential, the lower electrode is connected to ground potential and the upper electrode 114 is connected to an RF transmission line 118. The RF transmission line 118 is connected to an output O2 of the impedance matching circuit 118 for receiving the modulated RF signal 126.

[0039] In one embodiment, multiple processors are used in place of processor 120. For example, the functions described herein performed by processor 120 are instead performed in a distributed manner by multiple processors. Additionally, multiple memory devices are used in place of memory device 122. For example, information stored in memory device 122 is stored in a distributed manner among the multiple memory devices.

[0040] In one embodiment, functions described herein as being performed by processor 120 and a processor in RF generator 102 are alternatively performed by processor 120 or a processor in RF generator 102, or by three or more processors.

[0041] In one embodiment, in addition to the RF generator 102, one or more additional RF generators are connected to the impedance matching circuit 104. For example, the RF generator 102 is a kHz RF generator and the additional RF generator includes two MHz RF generators. As another example, the RF generator 102 is a MHz RF generator and the additional RF generator includes two MHz RF generators. The one or more additional RF generators are connected to corresponding one or more additional inputs of the impedance matching circuit 104 via corresponding one or more additional RF cables. The one or more additional RF generators generate corresponding one or more additional RF signals and provide the one or more additional RF signals to the impedance matching circuit 104 via corresponding one or more additional RF cables. The impedance matching circuit 104 matches the impedance of the load to the impedance of the source connected to the input I2 and the corresponding one or more additional inputs of the impedance matching circuit 104 to output the modulated RF signal at the output O2. Examples of sources connected to input I2 and to the corresponding one or more further inputs of impedance matching circuit 104 include one or more further RF cables, RF cable 116, RF generator 102, and one or more further RF generators.

[0042] In one embodiment, instead of being connected to the output O2, the current sensor 106 is connected to a point on the RF transmission line 108 or to the input I3 of the chuck 112 to measure the amount of current being delivered at that point or input I3. In this embodiment, the amount of power loss occurring from the output O1 of the RF generator 120 to the point or input I3 on ​​the RF transmission line 108 is determined and compensated for.

[0043] 2 is one embodiment of a graph 200 to illustrate the determination of a resistance (e.g., equivalent series resistance (ESR)) associated with the output O2 of the impedance matching circuit 104 (FIG. 1). The resistance associated with the output O2 is constant and is a combination (e.g., a sum) of the resistance of the RF cable 116 and the resistance of the circuit components of the impedance matching circuit 104. The circuit components of the impedance matching circuit 104 are connected between the input I2 and the output O2 of the impedance matching circuit 104.

[0044] Graph 200 plots in plot 202 the power delivered at output O1 of RF generator 102 on the y-axis and the squared amount of current measured at output O2 corresponding to the delivered power on the x-axis (FIG. 1). The delivered power at output O1 is measured in watts (W). During or after a plasma-free test, processor 120 accesses (reads or retrieves) from memory device 122 the amount of delivered power (e.g., Pdel1, Pdel2, etc.) at output O1. For example, prior to processing a substrate, processor 120 accesses from memory device 122 the amount of delivered power at output O1. The squared amount of current is Irms 2 Graph 200 is plotted on the x-axis as Irms, where Irms is measured in amperes by current sensor 106. Also, during or after the plasma-free test, processor 120 accesses quantities (Irms1, Irms2, etc.) in memory device 120. The quantities accessed correspond to amounts of delivered power accessed by processor 120 from memory device 122. During or after the plasma-free test, processor 120 calculates the square of the amount of current delivered at output O2 from the measured amounts of current stored in the database and plots it on graph 200.

[0045] Also, during or after the no plasma test, the processor 120 may calculate in graph 200 the square of the amount of current Irms1 delivered at the output O2. 2 Plot the amount of power delivered at output O1, Pdel1, against the square of the amount of power delivered at output O2, Irms2 2For example, point 204A in graph 200 plots the amount of power delivered at output O2 versus the amount of power delivered at output O2, Pdel1. 2 and another point 204B in the graph 200 represents the quantities Pdel2 and Irms2 2 Similarly, graph 200 includes other points 204C, 204D, 204E, and 204F, each of which corresponds to the amount of power delivered at output O1 of RF generator 102 and the square of the amount of current delivered at output O2 of impedance match circuit 104.

[0046] During or after the plasma-free test, processor 120 generates plot 202 from points 204A, 204B, 204C, 204D, 204E, and 204F. For example, processor 120 performs a linear regression analysis to fit a line through points 204A, 204B, 204C, 204D, 204E, and 204F. Each of points 204A-204F plots the amount of power delivered at output O1 against the square of the amount of current delivered at output O2.

[0047] Additionally, during or after the plasma-free test, the processor 120 calculates the slope of the plot 202. For example, the processor 120 may identify a number of points 204G and 204H located on the plot 202, project the point 204G horizontally onto the y-axis to determine an amount of delivered power P_delB at the output O1 of the RF generator 102, project the point 204H horizontally onto the y-axis to determine an amount of delivered power P_delA at the output O1 of the RF generator 102, and calculate the amount of current IrmsA squared at the output O1 of the RF generator 102. 2 Project point 204G vertically onto the x-axis to determine the square of the amount of current IrmsB at the output O1 of RF generator 102, IrmsB 2 The processor 120 projects the point 204H vertically onto the x-axis to determine a first difference between the quantities P_delB and P_delA and a quantity IrmsB 2 and IrmsA 2and calculate a ratio of the first and second differences to determine the slope of the plot 202. The processor 120 stores the slope as a resistance ESR associated with the output O2 of the impedance matching circuit 104.

[0048] 3 illustrates an embodiment of a system 300 to illustrate the use of a resistance ESR associated with an output O2 of an impedance matching circuit 104 in determining the amount of power P_sp_gen(i+1) generated and delivered by an RF generator 102 to account for power losses associated with the RF cable 116 and the impedance matching circuit 104. The system 300 is similar in structure to the system 100 of FIG. 1. For example, the system 300 includes the same components as the system 100. For example, the system 300 includes an RF generator 102, an RF cable 116, an impedance matching circuit 104, an RF transmission line 118, a plasma chamber 108, a current sensor 106, and a host computing device 110.

[0049] The plasma chamber 108 contains a substrate S1 (such as a semiconductor wafer) to be processed. Examples of substrate processing include deposition of one or more materials onto the substrate, etching the substrate, sputtering the substrate, and cleaning the substrate. The substrate S1 is disposed on an upper surface of a chuck 112 for processing.

[0050] During a first time period represented by an integer i, the processor 120 generates a command signal having an amount of power P_sp_rec generated by the RF generator 102 and output or delivered at the output O1. The terms time period, time increment, and time step are used interchangeably herein. The amount P_sp_rec is also referred to herein as a recipe set point of the operation of the RF generator 102, where "sp" refers to the set point and "rec" refers to the recipe. The processor 120 accesses (e.g., reads) the amount P_sp_rec from the memory device 122. The recipe set point of the operation is provided to the processor 120 by a user via an input device (e.g., a mouse, keyboard, or keypad) of the host computing device 110. The input device is connected to the processor 120 via a connecting cable.

[0051] Furthermore, during the first period, the processor 120 transmits a command signal having the quantity P_sp_rec to the RF generator 102 via the connecting cable 125 and the input I1. Upon receiving the command signal, the RF generator 102 generates an RF signal 302 having a power of the quantity P_sp_rec and provides the RF signal 302 to the impedance matching circuit 104 via the output O1 and the RF cable 116 and the input I2. During the first period, the RF signal 302 is generated in the same manner as the RF signal 124 (FIG. 1) is generated. For example, the processor of the RF generator 102 receives the command signal having the quantity P_sp_rec and generates a signal having that quantity. The processor of the RF generator 102 provides a signal having that quantity to a driver / amplifier circuit of the RF generator 102. The driver of the driver / amplifier circuit generates a current signal upon receiving a signal from the processor of the RF generator 102. The amplifier of the driver / amplifier circuit amplifies the power signal to output an amplified current signal, and transmits the amplified current signal to an RF power supply of the RF generator 102. The RF power supply oscillates to generate and provide an RF signal 302 having a power of the amount P_sp_rec.

[0052] During a first time period, the impedance matching circuit 104 receives the RF signal 302 at the input I2, matches the impedance of a load connected to the output O2 with the impedance of a source connected to the input I2, and outputs a modulated RF signal 304 at the output O2. The impedance matching circuit 104 provides the modulated RF signal 304 to the lower electrode of the chuck 112 via the output O2 and the RF transmission line 118. Additionally, one or more process gases are provided to the plasma chamber 108. When the one or more process gases are provided to the plasma chamber 108 and the modulated RF signal 304 is received by the lower electrode of the plasma chamber 108, a plasma is ignited and maintained in the plasma chamber 108, and the plasma processes the substrate S1.

[0053] While the modulated RF signal 304 is provided at the output O2 during a first time period, the current sensor 106 measures an amount I_RMS(i) of current delivered at the output O2, where i is an integer equal to or greater than zero. The amount I_RMS(i) is the root mean square of a plurality of amounts of current delivered at the output O2. The current sensor 106 provides the amount I_RMS(i) of current to the processor 120 via a connecting cable 121. While the substrate S1 is being processed, the processor 120 stores the amount I_RMS(i) in a memory device 122, accesses (e.g., reads or retrieves) the amount I_RMS(i) from the memory device 122, and measures the square of the amount I_RMS(i) of current during the first time period, I_RMS(i). 2 The processor 120 calculates the squared I_RMS(i) 2 Also, during a first period when the substrate S1 is being processed in the plasma processing chamber 108, the processor 120 retrieves from the memory device 122 the amount and value of the resistance ESR associated with the output O2, I_RMS(i), 2 and access (read or get, etc.) the square of the amount of current through the resistance ESR, I_RMS(i) 2to calculate or determine an amount P_loss(i) of RF power loss at the output O2 of the impedance matching circuit 104. The amount P_loss(i) is the amount of power lost in or by the RF cable 116 combined with the amount of power lost in or by the circuit components of the impedance matching circuit 104 between the input I2 and the output O2 of the impedance matching circuit 104. Within a first time period, the processor 120 calculates a sum P_sp_gen(i+1) of the amount P_sp_rec and the amount P_loss(i) of power associated with the output O2 and outputs the amount of delivered power P_sp_gen(i+1), where “gen” refers to the RF generator 102.

[0054] During the second period during which the substrate S1 is being processed, instead of continuing to generate a command signal having an amount of power P_sp_rec, the processor 120 generates a command signal having an amount of delivered power P_sp_gen(i+1) and transmits the command signal to the RF generator 102 via the connecting cable 125 and the input I1 to adjust (e.g., change or modify) the recipe set point P_sp_rec of the operation of the RF generator 102. As an example, the second period is a period following the first period (e.g., a period consecutive to the first period). For example, there is no period between the first period and the second period. As another example, the second period follows the first period after some time.

[0055] Furthermore, during the second time period, upon receiving a command signal having an amount P_sp_gen(i+1), the RF generator 102 generates an RF signal 302 having an amount P_sp_gen(i+1) of delivered power at the output O1. The RF generator 102 processes the command signal having the amount P_sp_gen(i+1) to output an RF signal 302 having the amount P_sp_gen(i+1) in the same manner as described above for outputting an RF signal 302 having an amount P_sp_rec of power. For example, during the second time period, the processor 120 adjusts (e.g., modifies or changes) the recipe set point P_sp_rec to achieve the amount P_sp_gen(i+1) and provides a command signal having the amount P_sp_gen(i+1) to the RF generator 102 via the connecting cable 125. Upon receiving the command signal, the processor of the RF generator 102 generates a signal having the amount P_sp_gen(i+1) and transmits it to the driver / amplifier circuit of the RF generator 102. Upon receiving the signal having the quantity P_sp_gen(i+1), the driver / amplifier circuit generates a current signal based on the quantity P_sp_gen(i+1) and provides the current signal to a power supply of the RF generator 102. The power supply of the RF generator 102 oscillates according to the current signal to output an RF signal 302 having the quantity P_sp_gen(i+1).

[0056] An RF signal 302 having an amount of transmitted power P_sp_gen(i+1) is provided by the RF generator 102 to the impedance matching circuit 104 via the output O1, the RF cable 116, and the input I2. The impedance matching circuit 104 matches the impedance of the load connected to the output O2 with the impedance of the source connected to the input I2, and modulates the RF signal 302 having the amount of transmitted power P_sp_gen(i+1) to output a modulated RF signal 304. The lower electrode receives the modulated RF signal 304 output based on the amount of transmitted power P_sp_gen(i+1) to process the substrate S1. The modulated RF signal 304 is received by the lower electrode via the output O2 and the RF transmission line 118.

[0057] Again during the second time period, the current sensor 106 measures an amount of current delivered at the output O2, I_RMS(i+1), and provides the amount to the processor 120 via the connecting cable 121. The processor stores the amount I_RMS(i+1) in the memory device 122. During the second time period, the processor 120 accesses (e.g., retrieves or reads) the amount I_RMS(i+1) from the memory device 122 and determines or calculates an amount of delivered power loss P_loss(i+1) at the output O2 by multiplying the amount I_RMS(i+1) squared by the resistance ESR associated with the output O2. Additionally, during the second time period, the processor 120 calculates the sum of the amount of power P_sp_rec and the amount of power loss P_loss(i+1) to output an amount of delivered power P_sp_gen(i+2).

[0058] During a third time period when the substrate S1 is being processed, the processor 120 controls the RF generator 102 to generate an RF signal 302 having an amount P_sp_gen(i+2) of delivered power to adjust a recipe set point P_sp_rec of the power supplied at the output O1. For example, during the third time period, the processor 120 adjusts (e.g., modifies or changes) the recipe set point P_sp_rec to achieve the amount P_sp_gen(i+2) and provides a command signal having the amount P_sp_gen(i+2) to the RF generator 102 via the connecting cable 125. Upon receiving the command signal from the processor 120, the processor of the RF generator 102 sends a signal having the amount P_sp_gen(i+2) to a driver / amplifier circuit of the RF generator 102. Upon receiving the signal having the amount P_sp_gen(i+2), the driver / amplifier circuit generates a current signal based on the amount P_sp_gen(i+2) and provides the current signal to the power supply. The power supply oscillates according to the current signal to output an RF signal 302 having an amount P_sp_gen(i+2). The third time period is a time period subsequent to the second time period. In a similar manner, during further time periods during which the substrate S1 is being processed, the processor 120 continues to control the RF generator 102 to vary the amount of delivered power of the RF signal 302 to account for or compensate for power losses associated with the output O2 of the impedance matching circuit 104 (e.g., power losses at the output O2, etc.).

[0059] FIG. 4 illustrates an embodiment of a table 400 to illustrate how the processor 120 continues to modify the amount of delivered power at the output O1 of the RF generator 102 based on the amount of power loss associated with the output O2 of the impedance matching circuit 104 (FIG. 3) during processing of the substrate S1 or another substrate. The table 400 includes a list of time steps, a list of correction offsets to be applied to the recipe set point P_sp_rec, the generator set point, the loss of power P_loss associated with the output O2, the amount of power coupled to the plasma in the plasma chamber 108 (FIG. 1), and the correction offset for the next time step. Examples of the power loss P_loss include P_loss(i) and P_loss(i+1). The power loss P_loss is used to adjust the recipe set point P_sp_rec when the amount of power loss is added to the recipe set point P_sp_rec. The correction offsets, the generator set point, the loss of power, the amount of power coupled to the plasma, and the correction offset for the next time step are measured in watts (W).

[0060] Examples of time steps include a first period, a second period, and a third period. For example, the first period is an example of time step 0, the second period is an example of time step 1, and the third period is an example of time step 2. As another example, the first period is an example of time step 4, the second period is an example of time step 5, and the third period is an example of time step 6. For example, the first period is an example of time step 3, the second period is an example of time step 4, and the third period is an example of time step 5.

[0061] Examples of generator set points include the quantity P_sp_rec as an initial generator recipe set point, the quantity P_sp_gen(i+1), and the quantity P_sp_gen(i+2). Further, examples of losses of power associated with output O2 include the quantity P_loss(i) and the quantity P_loss(i+1). During each time step, the loss of power associated with output O2 is equal to the correction offset for the next time step. For example, the correction offset is 5 W during time step 2, which is equal to a loss of 5 W of power during time step 1.

[0062] During time step 0, the processor 120 controls the RF generator 102 to generate an RF signal 302 (FIG. 3) having an amount of 500 W. The amount 500 W is an example of a recipe set point P_sp_rec of power. Additionally, during time step 0, the processor 120 accesses from the memory device 122 an amount of delivered power loss 5 W associated with the output O2. The amount of delivered power loss 5 W at the output O2 is calculated by the processor 120 by multiplying an amount of current (e.g., I_RMS(i)) measured by the current sensor 106 (FIG. 3) by the resistance ESR. The amount of current I_RMS(i) is measured by the current sensor 106 during time step 0. Also, during time step 0, an amount of delivered power of 495 W is coupled into the plasma used to process the substrate S1. The amount 495 W is the difference between the amount of power of the RF signal 302 500 W and the amount of power loss 5 W at the output O2. During time step 0, processor 120 determines the amount of correction offset for the next time step, 5W, to be equal to the amount of power loss associated with output O2, 5W.

[0063] During time step 1, the processor 120 calculates the sum of the recipe set point 500W and the next time step correction offset 5W determined during time step 0, and controls the RF generator 102 to generate an RF signal 302 having an amount 505W that is the sum. The amount 505W is an example of an amount of power P_sp_gen(i+1) delivered by the RF generator 102 at the output O1 of the RF generator 102. Additionally, during time step 1, the processor 120 accesses from the memory device 122 an amount of delivered power loss 8W at the output O2. The amount of delivered power loss 8W is calculated by the processor 120 by multiplying the amount of current (e.g., I_RMS(i+1)) measured by the current sensor 106 (FIG. 3) by the square of the resistance ESR. The amount of current I_RMS(i+1) is measured by the current sensor 106 during time step 1. Also, during time step 1, an amount of delivered power of 497 W is coupled into the plasma used to process substrate S1. The amount 497 W is the difference between the amount of delivered power 505 W of RF signal 302 and the amount of power loss associated with output O2, 8 W. During time step 1, processor 120 determines an amount of correction offset for the next time step, 8 W, to be equal to the amount of power loss associated with output O2, 8 W.

[0064] During time step 2, the processor 120 calculates the sum of the recipe set point 500W and the next time step correction offset 8W determined during time step 1, and controls the RF generator 102 to generate the RF signal 302 having a quantity 508W that is the sum. Time step 2 is a time step consecutive to the time step. The quantity 508W is an example of an amount of power delivered by the RF generator 102, P_sp_gen(i+2). Additionally, during time step 2, the processor 120 accesses from the memory device 122 an amount of delivered power loss at the output O2, 9W. The amount of delivered power loss at the output O2, 9W, is calculated by the processor 120 by multiplying an amount of current (e.g., I_RMS(i+2)) measured by the current sensor 106 (FIG. 3) by the square of the resistance ESR. The quantity I_RMS(i+2) is stored by the processor 120 in the memory device 122. An amount of current I_RMS(i+2) is measured by the current sensor 106 during time step 2. Also during time step 2, an amount of delivered power of 499 W is coupled into the plasma used to process the substrate S1. The amount 499 W is the difference between the amount of delivered power 508 W of the RF signal 302 and the amount of power loss 9 W associated with the output O2. During time step 2, the processor 120 determines an amount of correction offset for the next time step, 9 W, to be equal to the amount of power loss 9 W associated with the output O2.

[0065] During time step 3, the processor 120 calculates the sum of the recipe set point 500W and the next time step correction offset 9W determined during time step 2, and controls the RF generator 102 to generate an RF signal 302 having an amount 509W that is the sum. Time step 3 is a time step that is consecutive or subsequent to time step 2. The amount 509W is an example of an amount of power delivered by the RF generator 102, P_sp_gen(i+3). Additionally, during time step 3, the processor 120 accesses from the memory device 122 an amount of delivered power loss at the output O2, 10W. The amount of delivered power loss at the output O2, 10W, is calculated by the processor 120 by multiplying an amount of current (e.g., I_RMS(i+3)) measured by the current sensor 106 (FIG. 3) by the square of the resistance ESR. The amount 10W is measured by the current sensor 106 and provided to the processor 120. An amount of current I_RMS(i+3) is measured by the current sensor 106 during time step 3. Also during time step 3, an amount of delivered power of 499 W is coupled into the plasma used to process the substrate S1. The amount 499 W is the difference between the amount of delivered power 509 W of the RF signal 302 and the amount of power loss 10 W associated with the output O2. During time step 3, the processor 120 determines an amount of correction offset for the next time step, 10 W, to be equal to the amount of power loss 10 W associated with the output O2.

[0066] During time step 4, the processor 120 calculates the sum of the recipe set point 500 W and the next time step correction offset 10 W determined during time step 3, and controls the RF generator 102 to generate an RF signal 302 having an amount 510 W that is the sum. Time step 4 is a time step that is consecutive or subsequent to time step 3. The amount 510 W is an example of an amount of power delivered by the RF generator 102, P_sp_gen(i+4). Additionally, during time step 4, the processor 120 accesses from the memory device 122 an amount of delivered power loss at the output O2, 10.5 W. The amount of delivered power loss at the output O2, 10.5 W, is calculated by the processor 120 by multiplying an amount of current (e.g., I_RMS(i+4)) measured by the current sensor 106 (FIG. 3) by the square of the resistance ESR. The amount of current I_RMS(i+4) is measured by the current sensor 106 during time step 4. Also, during time step 4, an amount of delivered power of 499.5 W is coupled into the plasma used to process substrate S1. The amount of 499.5 W is the difference between the amount of delivered power 510 W of RF signal 302 and the amount of power loss associated with output O2 of 10.5 W. During time step 4, processor 120 determines an amount of correction offset for the next time step of 10.5 W to be equal to the amount of power loss associated with output O2 of 10.5 W.

[0067] During time step 5, the processor 120 calculates the sum of the recipe set point 500W and the next time step correction offset 10.5W determined during time step 4, and controls the RF generator 102 to generate an RF signal 302 having an amount 510.5W that is the sum. Time step 5 is a time step that is consecutive or subsequent to time step 4. The amount 510.5W is an example of an amount of power delivered by the RF generator 102, P_sp_gen(i+5). Additionally, during time step 5, the processor 120 accesses from the memory device 122 an amount of delivered power loss 10.6W associated with the output O2. The amount of delivered power loss 10.6W at the output O2 is calculated by the processor 120 by multiplying the amount of current I_RMS(i+5) measured by the current sensor 106 (FIG. 3) squared and the resistance ESR. An amount of current (e.g., I_RMS(i+5)) is measured by the current sensor 106 during time step 5. Also during time step 5, an amount of delivered power of 499.9 W is coupled into the plasma used to process the substrate S1. The amount of 499.9 W is the difference between the amount of delivered power 510.5 W of the RF signal 302 and the amount of power loss associated with the output O2, 10.6 W. During time step 5, the processor 120 determines an amount of correction offset for the next time step, 10.6 W, to be equal to the amount of power loss associated with the output O2, 10.6 W.

[0068] During time step 6, the processor 120 calculates the sum of the recipe set point 500W and the next time step correction offset 10.6W determined during time step 5, and controls the RF generator 102 to generate an RF signal 302 having an amount 510.6W that is the sum. Time step 6 is a time step that is consecutive or subsequent to time step 5. The amount 510.6W is an example of an amount of power delivered by the RF generator 102, P_sp_gen(i+6). Additionally, during time step 6, the processor 120 accesses from the memory device 122 an amount of delivered power loss at the output O2, 10.6W. The amount of delivered power loss at the output O2, 10.6W, is calculated by the processor 120 by multiplying the amount of current (e.g., I_RMS(i+6)) measured by the current sensor 106 (FIG. 3) squared by the resistance ESR. An amount of current I_RMS(i_6) is measured by the current sensor 106 during time step 6. The amount of current I_RMS(i+6) is stored in the memory device 122 by the processor 120 and accessed (e.g., read or retrieved) from the memory device 122 by the processor 120. Also during time step 6, an amount of delivered power of 500 W is coupled into the plasma used to process the substrate S1. The amount 500 W is the difference between the amount of delivered power 510.6 W of the RF signal 302 and the amount of power loss 10.6 W associated with the output O2. During time step 6, the processor 120 determines an amount of correction offset for the next time step, 10.6 W, to be equal to the amount of power loss 10.6 W associated with the output O2.

[0069] In this manner, the processor 120 continues to control the amount of power delivered by the RF generator 102 at the output O1 of the RF generator 102 based on the amount of power loss measured at the output O2 of the impedance matching circuit 104 until the amount of power loss is compensated for. The amount of power loss is compensated for when the amount of power loss is stable. For example, during time steps 5 and 6, the processor 120 determines that the same amount of power loss of 10.6 W has occurred based on the amount of current delivered at the output O2 measured by the current sensor 106 and the resistance ESR associated with the output O2. Upon determining that the amount of power loss is stable, the processor 120 controls the RF generator 102 to not change the amount of power delivered by the RF generator 102 at the output O1 of the RF generator 102. For example, after time step 6, the processor 120 controls the RF generator 102 to deliver an amount of 510.6 W of power at the output O1 of the RF generator 102, and does not change the amount 510.6 W. By way of further example, after time step 6, the current sensor 106 is disconnected from the output O2 of the impedance matching circuit 104. It is not necessary to continue to measure the current at the output O2 in order to determine the amount of delivered power loss at the output O2.

[0070] In one embodiment, instead of determining the same amount of power loss for two consecutive time steps, processor 120 determines that the amount of power loss during two consecutive time steps is within a predetermined range of each other to determine that the amount of power loss of the latter of the two time steps is stable. For example, assume that the amount of power loss during time step 5 is 10.61 W instead of 10.6 W, and the amount of power loss during time step 6 is 10.6 W, processor 120 determines that the amounts 10.6 W and 10.61 W are within a predetermined range of 0.1 W or 0.2 W from each other to determine that the amount of power loss 10.6 W is stable during time step 6. As another example, assume that the amount of power loss during time step 5 is 10.62 W instead of 10.6 W, and the amount of power loss during time step 6 is 10.6 W, processor 120 will determine that the amounts 10.6 W and 10.62 W are within a predetermined range of 0.2 W or 0.3 W of each other and determine that the amount of power loss during time step 6, 10.6 W, is stable.

[0071] In one embodiment, the iterations of the method of measuring the current at the output O2 of the impedance matching circuit 104, determining the amount of power loss at the output O2 of the impedance matching circuit 104 from the current measurements and the resistance ESR, and determining the amount of power loss and the amount of power delivered by the RF generator 102 from the recipe set point of the RF generator 102 are performed at a rate in the range of 50 Hertz (Hz) to 1 kHz. For example, the measurement of the amount of current (e.g., I_RMS(i)) at the output O2, the determination of the amount P_loss(i) from the measurements I_RMS(i) and the resistance ESR, and the determination of the amount P_sp_gen(i+1) from the recipe set point P_sp_rec and the amount P_loss(i) are repeated iteratively 50 times per second, 1000 times per second, or between 50 times per second and 1000 times per second. As another example, 50 or 1000 time steps (example time steps are provided above with respect to table 400) occur per second. During each time step, an amount of current (such as I_RMS(i)) is measured at the output O2, a quantity P_loss(i) is determined from the measurement I_RMS(i) and the resistance ESR, and a quantity P_sp_gen(i+1) is determined from the recipe set point P_sp_rec and the quantity P_loss(i).

[0072] In one embodiment, the amount 510W is an example of an amount of power P_sp_gen(i) delivered by the RF generator 102, the amount 510.5W is an example of an amount of power P_sp_gen(i+1) delivered by the RF generator 102, and the amount 510.6W is an example of an amount of power P_sp_gen(i+2) delivered by the RF generator 102.

[0073] FIG. 5 illustrates an embodiment of a graph 500 to illustrate how the power P_sp_gen delivered by the RF generator 102 (FIG. 3) at the output O1 varies taking into account the loss P_loss of the power delivered at the output O2 of the impedance matching circuit 104 (FIG. 3). Note that "sp" in the term "P_sp_gen" represents a set point and "gen" in the term "P_sp_gen" represents the RF generator 102. The graph 500 plots the power P_sp_gen delivered by the RF generator 102 versus time t. The graph 500 includes a plot 502, another plot 504, and yet another plot 506. The plot 502 illustrates the delivered power P_sp_ge at the output O1 of the RF generator 102. Additionally, the plot 504 illustrates the loss P_loss of the power delivered at the output O2 of the impedance matching circuit 104, and the plot 506 illustrates a recipe set point P_sp_rec, which is a constant amount.

[0074] As shown in graph 500, as the amount of loss of delivered power P_loss (P_loss(i), P_loss(i+1), P_loss(i+2), etc.) increases with time t, the amount of delivered power P_sp_gen (e.g., P_sp_gen(i), P_sp_gen(i+1), P_sp_gen(i+2), P_sp_gen(i+3), P_sp_gen(i+4), P_sp_gen(i+5), P_sp_gen(i+6), etc.) increases with time t. By accounting for the loss of delivered power P_loss, uniformity in the processing of the substrate S1 (FIG. 4) or another substrate is achieved with time t. Note that the difference between the delivered power P_sp_gen and the recipe set point P_sp_rec is referred to herein as the set point offset.

[0075] 6 illustrates an embodiment of a system 600 for illustrating an application of the method for compensating for loss of transmitted power. The system 600 includes a comparator 602, a controller 604, a summer 606, an RF generator 102, an impedance matching circuit 104, a plasma chamber 108, a current sensor 106, a delay circuit 608, a filter 610, a controller 611, and a comparator 612.

[0076] Examples of the controller 604 include the processor 120 (FIG. 3), an ASIC, a PLD, a CPU, a microprocessor, and a microcontroller. Another example of the controller 604 includes a combination of the processor 120 and the processor of the RF generator 102. Examples of the comparison 602 or the comparator 612 include a controller, a processor, a PLD, a CPU, a microprocessor, and a microcontroller. Each of the summer 606, the delay circuit 608, and the filter 610 may be implemented using a controller, a processor, a PLD, a CPU, a microprocessor, and a microcontroller. An example of the filter 610 includes a low pass filter that filters out high frequencies of the current I_RMS.

[0077] The comparator 602 is connected to a controller 604, which is connected to a summer 606. The summer 606 is connected to the RF generator 102 via a connection cable. The delay circuit 608 is connected to the current center 106 via a connection cable. The delay circuit 608 is connected to a filter 610, which is connected to a controller 611. The controller 611 is connected to a comparator 612, which is connected to the comparator 602.

[0078] The power sensor 106 measures and provides an amount of current I_RMS (I_RMS(i), I_RMS(i+1), I_RMS(i+2), I_RMS(i+3), I_RMS(i+4), I_RMS(i+5), or I_RMS(i+6), etc.) measured during processing of a substrate or an amount of current Irms measured during plasma-free testing to a delay circuit 608. The delay circuit 608 accounts for (e.g., reduces or eliminates) a time delay associated with the current I_RMS measured during processing of a substrate or associated with the current Irms measured during plasma-free testing. For example, the delay circuit 608 reduces or eliminates a time delay in receiving the amount of current I_RMS from the current sensor 106 by the processor 120, a time delay in processing the current measurement I_RMS and the resistance ESR by the processor 120 to determine the power loss P_loss at the output O2 of the impedance matching circuit 102, and a time delay in determining the amount of delivered power P_sp_gen from the power loss P_loss and the recipe set point P_sp_rec by the processor 120. As another example, the delay circuit 608 reduces or eliminates a time delay in receiving the amount of current Irms from the current sensor 106 by the processor 120. The delay circuit 608 reduces or eliminates a time delay associated with the current I_RMS and a time delay associated with the current Irms and provides the current measurement I_RMS or the current measurement Irms (e.g., amount, etc.) to the filter 610.

[0079] The filter 610 removes (e.g., filters) high frequency components of the amount of current I_RMS or the amount of current Irms measured by the current sensor 106. The controller 611 determines the value of the resistor ESR from the relationship between the amount of current Irms measured by the current sensor 106 and the amount of delivered power P_del shown in the graph 200 (FIG. 2). The controller 611 also determines the amount of power loss P_loss from the resistor ESR and the square of the current I_RMS, and provides the amount of delivered power loss P_loss to the comparator 612.

[0080] Comparator 612 compares the amount of power delivered to input I2 of impedance match circuit 104 with the amount of delivered power loss, P_loss, to determine the amount of delivered power, P_coupled, that is coupled to the plasma in plasma chamber 108. The power delivered to input I2 is designated as P_del. Comparator 612 provides the amount of delivered power, P_coupled, that is coupled to the plasma to comparator 602.

[0081] Additionally, the comparator 602 compares the amount of power coupled to the plasma in the plasma chamber 108, P_coupled, with the recipe set point P_sp_rec to determine an amount of delivered power loss P_loss at the output O2 of the impedance matching circuit 104. The controller 604 receives the amount of delivered power loss P_loss at the output O2 of the impedance matching circuit 104 from the comparator 602 and provides the amount of loss to the adder 606. The adder 606 adds the amount of delivered power loss P_loss at the output O2 of the impedance matching circuit 104 to the recipe set point P_sp_rec to generate a total or aggregate set point, which is provided as an input to the RF generator 102 via a connecting cable. The RF generator 102 is operated to generate and provide a total set point of delivered power at the output O1 of the RF generator 102.

[0082] In one embodiment, the delay circuit 608, the filter 610, the controller 611, the comparator 612, the comparator 602, the controller 604, and the adder 606 are implemented within the processor 120. For example, the delay circuit 608, the filter 610, the controller 611, the comparator 612, the comparator 602, the controller 604, and the adder 606 are part of the processor 120.

[0083] In one embodiment, filter 610 is optional and may not be used in system 600. For example, delay circuit 608 is not connected to filter 610 but rather is connected to controller 611.

[0084] In one embodiment, the functions described herein performed by delay circuit 608, filter 610, controller 611, comparator 612, comparator 602, controller 604, and summer 606 are performed by one or more processors. For example, the functions described herein performed by delay circuit 608, filter 610, and controller 611 are performed by one processor, and the functions described herein performed by comparator 612, comparator 602, controller 604, and summer 606 are performed by another processor (e.g., processor 120).

[0085] FIG. 7 illustrates an embodiment of a system 700 to illustrate that the delivered power P_sp_gen determined by applying the method described with respect to FIG. 3 or FIG. 4 is maintained for processing another substrate S2 after processing the substrate S1. The system 700 includes the same components as the system 300, except that the system does not include the current sensor 106. The current sensor 106 is not connected to the output O2 of the impedance matching circuit 104. For example, the current sensor 106 is disconnected from the output O2 of the impedance matching circuit 104. Furthermore, the substrate S1 disposed on the upper surface of the chuck 112 is removed from the plasma chamber 108, and after the substrate S1 is removed, the substrate S2 is disposed on the upper surface for processing.

[0086] Once the processor 120 determines an amount of delivered power (e.g., P_sp_gen(i+1), P_sp_gen(i+10), or 510.6 W (FIG. 4), etc.) provided by the RF generator 102 such that the amount of power loss P_loss is within a predetermined range over multiple time steps (e.g., multiple periods), the processor 120 does not change the amount of delivered power provided by the RF generator 102. For example, the processor 120 provides a command signal having an amount 510.6 W to the RF generator 102 to generate an RF signal 302 having a delivered power of the amount 510.6 W during each time step after time step 6 of FIG. 4. Upon receiving the command signal having the amount 510.6 W, the RF generator 102 generates the RF signal 302 having the amount 510.6 W and provides the RF signal 302 to the impedance matching circuit 104 via the output O1 and the input I2.

[0087] Upon receiving the RF signal 302, the impedance match circuit 104 matches the impedance of a load connected to output O2 to the impedance of a source connected to input I2 to output a modulated RF signal 304. One or more process gases are supplied to the plasma chamber 108, and the modulated RF signal 304 is supplied to the lower electrode of the chuck 112, and a plasma is ignited or sustained in the plasma chamber 108. The plasma in the plasma chamber 108 processes a substrate S2 disposed in the plasma chamber 108.

[0088] 3 and 4 of measuring the current I_RMS at the output O2 of the impedance matching circuit, determining the power loss P_loss at the output O2 from the current I_RMS and the resistance ESR, and determining the delivered power P_sp_gen to be applied to the RF generator 104 based on the power loss P_loss and the recipe set point P_sp_rec is repeated for substrate S2 in one or more time steps after processing of substrate S1. The delivered power P_sp_gen determined for substrate S2 is then applied to substrate S2 in a further time step.

[0089] In one embodiment, the method described herein for compensating for RF power loss is applied to other types of semiconductor processing tools, such as an inductively coupled plasma (IC) tool, an electron cyclotron resonance (ECR) tool, or a plasma enhanced chemical vapor deposition (PECVD) tool. For example, instead of the CCP plasma chamber 108, an ICP plasma chamber, an ECR plasma chamber, or a PECVD plasma chamber is used. For example, the RF transmission line 118 is connected to the lower electrode of the ICP plasma chamber. In this example, a transformer coupled plasma (TCP) coil of the ICP plasma chamber is connected to a ground potential or is also connected to one or more RF generators through an impedance matching circuit. As another example, the RF transmission line 118 is connected to the pedestal of the PECVD plasma chamber. As yet another example, the RF transmission line 118 is connected to the TCP coil of the ICP plasma chamber. In this example, a lower electrode of the ICP plasma chamber is connected to a ground potential or is also connected to one or more RF generators through an impedance matching circuit. It is noted that the plasma chamber 108 is a type of semiconductor processing tool.

[0090] The embodiments described herein may be implemented with a variety of computer system configurations, including handheld hardware units, microprocessor systems, microprocessor-based or programmable consumer electronics, minicomputers, mainframe computers, etc. The embodiments described herein may also be implemented in distributed computing environments where tasks are performed by remote processing hardware units that are linked through a computer network.

[0091] In some embodiments, the controller is part of a system, which may be part of the examples described above. The system includes semiconductor processing equipment, such as one or more processing tools, one or more chambers, one or more platforms for processing, and / or specific processing components (wafer pedestal, gas flow system, etc.). The system is integrated with electronics for controlling the operation of the system before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as a "controller" and may control various components or sub-parts of the system. The controller is programmed to control any of the processes disclosed herein, such as supply of process gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, RF generator settings, RF matching circuit settings, frequency settings, flow settings, fluid supply settings, position and motion settings, and wafer movement in and out of load locks connected or coupled to the tool and other moving tools and / or systems, depending on the processing requirements and / or type of system.

[0092] In general, 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 end-point measurements, etc. Integrated circuits include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as ASICs, PLDs, one or more microprocessors, or 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 operational parameters for performing processing on or for semiconductor wafers. The operational parameters, in some embodiments, are part of a recipe defined by a process engineer to accomplish one or more processing steps during processing of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies of a wafer.

[0093] The controller, in some embodiments, is part of or connected to a computer that is integrated with, connected to, or otherwise networked with the system, or a combination thereof. For example, the controller may be in the "cloud" or may be all or part of a fab host computer system that allows remote access for wafer processing. The controller allows remote access to the system to monitor the current progress of a manufacturing operation, look at the history of past manufacturing operations, or look at trends or performance indicators from multiple manufacturing operations, to change parameters of a current process, set up a process step according to a current process, or initiate a new process.

[0094] In some embodiments, a remote computer (e.g., a server) provides process recipes to the system via a computer network (including a local network or the Internet). The remote computer includes a user interface that allows for input or programming of parameters and / or settings, which are communicated from the remote computer to the system. In some examples, the controller receives instructions in the form of settings for processing the wafer. It should be understood that the settings are specific to the type of processing to be performed on the wafer and the type of tool the controller interfaces with or controls. Thus, as described above, the controller is distributed, such as by having one or more separate controllers that are networked and operate toward a common purpose (such as performing processing as described herein). One example of a distributed controller for such purposes includes one or more integrated circuits on the chamber that communicate with one or more remotely located integrated circuits (e.g., located at the platform level or remotely as part of a remote computer) that cooperate to control processing at the chamber.

[0095] Without being limited thereto, in various embodiments, the plasma system includes a plasma etch chamber, a deposition chamber, a spin rinse chamber, a metal plating chamber, a cleaning chamber, a bevel edge etch chamber, a physical vapor deposition (PVD) chamber, a chemical vapor deposition (CVD) chamber, an atomic layer deposition (ALD) chamber, an atomic layer etch (ALE) chamber, an ion implantation chamber, a track chamber, and any other semiconductor processing system associated with or utilized in the fabrication and / or manufacturing of semiconductor wafers.

[0096] Also, it should be noted that while the above operations are described with respect to a parallel plate plasma chamber, in some embodiments, the above operations apply to other types of plasma chambers, such as plasma chambers with transformer coupled plasma (TCP) reactors, dielectric tools, electron cyclotron resonance (ECR) reactors, etc. An example of a TCP reactor includes an inductively coupled plasma (ICP) reactor. Another example of a TCP reactor includes a conductor tool. At times, the terms reactor and plasma chamber are used interchangeably herein.

[0097] As described above, depending on the processing operations being performed by the tool, the controller communicates with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools located throughout the factory, a main computer, another controller, or tools used in material transport to carry containers of wafers to and from tool locations and / or load ports within a semiconductor manufacturing factory.

[0098] With the above embodiments in mind, it should be understood that some of the embodiments employ various computer-implemented operations involving data stored in computer systems. The computer-implemented operations are operations that involve physical quantities.

[0099] Some of the embodiments further relate to hardware units or devices for performing these operations. The device is specially configured for a special purpose computer. When defined as a special purpose computer, the computer can operate for a specific purpose while performing other processes, program executions or routines that are not included in the specific purpose.

[0100] In some embodiments, the operations described herein are processed on a computer selectively activated or configured by one or more computer programs stored in a computer memory or obtained over a computer network. When data is obtained over a computer network, the data may be processed by other computers on the computer network (e.g., a cloud of computing resources).

[0101] One or more embodiments described herein may be manufactured as computer readable code on a non-transitory computer readable medium. A non-transitory computer readable medium is any data storage hardware unit (e.g., 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-rewriteable (CD-RW), magnetic tape, and other optical and non-optical data storage hardware units. In some embodiments, the non-transitory computer readable medium includes a computer readable tangible medium distributed over networked computer systems such that the computer readable code is stored and executed in a distributed manner.

[0102] Although some of the method actions described above are presented in a particular order, it should be understood that in various embodiments, other housekeeping operations are performed between the method actions, or the method actions are performed at slightly different times, distributed across a system that allows the method actions to occur at various intervals, or arranged to be performed in an order different from that described above.

[0103] Furthermore, it should be noted that in one embodiment, one or more features of any embodiment described herein may be combined with one or more features of any other embodiment without departing from the scope described in the various embodiments described in this disclosure.

[0104] Although the present embodiments have been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be made within the scope of the appended claims. Thus, the present embodiments are to be considered as illustrative and not restrictive, and the embodiments are not to be limited to the details given herein, but may be modified within the scope of the appended claims and their equivalents.

Claims

1. 1. A method for compensating for radio frequency (RF) power losses, comprising: obtaining a plurality of measurements of a plurality of parameters associated with components of the plasma system; determining a resistance associated with the component of the plasma system from the plurality of measurements of the plurality of parameters; obtaining a value of a parameter of the plurality of parameters associated with the component of the plasma system; determining an amount of the RF power loss associated with the component of the plasma system from the resistance and the value of the one of the plurality of parameters; adjusting a set point of operation of the RF generator based on the amount of RF power loss; repeating the steps of determining one or more additional values ​​for the one of the plurality of parameters, determining one or more additional amounts of the RF power loss, and modifying the set point of operation of the RF generator until the amount of adjustment applied to the set point compensates for the RF power loss; A method comprising:

2. 2. The method of claim 1, wherein the amount of adjustment being applied to the set point compensates for a plurality of RF power losses when each of the RF power losses falls within a predetermined range.

3. 10. The method of claim 1, wherein the taking of the measurements and the determining of the resistance are performed during or after a plasma-free test.

4. 10. The method of claim 1, wherein the obtaining of the value, the determining of the amount of RF power loss, the adjusting of the set point, and the repeating are performed during processing of a substrate.

5. The method of claim 1 , wherein the component of the plasma system is an impedance matching circuit.

6. 2. The method of claim 1, wherein determining the amount of RF power loss comprises multiplying the resistance by a square of the value of the one of the multiple parameters.

7. 2. The method of claim 1, wherein adjusting the set point of operation of the RF generator is performed to control the RF generator to operate at a second set point; The repetition obtaining a second value of the one of the plurality of parameters associated with the component of the plasma system; determining a second RF power dissipation amount from the resistance and the second value of the one of the plurality of parameters; adjusting the set point of operation of the RF generator based on the second amount of RF power loss, the method being performed to control the RF generator to operate at a third set point, the set point of operation of the RF generator based on the second amount of RF power loss.

8. The method of claim 1 , wherein adjusting the set point comprises adding the amount of RF power loss to the set point.

9. 1. A controller for compensating for radio frequency (RF) power losses, comprising:

1. A processor comprising: obtaining a plurality of measurements of a plurality of parameters associated with components of the plasma system; determining a resistance associated with the component of the plasma system from the plurality of measurements of the plurality of parameters; obtaining a value of a parameter of the plurality of parameters associated with the component of the plasma system; determining an amount of the RF power loss associated with the component of the plasma system from the resistance and the value of the one of the plurality of parameters; adjusting a set point of operation of the RF generator based on the amount of RF power loss; a processor configured to repeat determining one or more additional values ​​for the one of the plurality of parameters, determining one or more additional amounts of the RF power loss, and adjusting the set point of operation of the RF generator until the amount of adjustment applied to the set point compensates for the RF power loss; a memory device coupled to the processor for storing the plurality of measurements of the plurality of parameters; A controller comprising:

10. 10. The controller of claim 9, wherein the processor determines that the amount of adjustment being applied to the set point compensates for the RF power loss when a plurality of RF power loss amounts each fall within a predetermined range.

11. 10. The controller of claim 9, wherein the processor takes the measurements and determines the resistance during or after a plasma-free test.

12. 10. The controller of claim 9, wherein the processor obtains the value of the one parameter of the plurality of parameters, determines the amount of RF power loss, adjusts the set point, and repeats obtaining the one or more further values, determining the one or more further amounts of RF power loss, and adjusting the set point for operation of the RF generator during processing of a substrate.

13. 10. The controller of claim 9, wherein the component of the plasma system is an impedance matching circuit.

14. 10. The controller of claim 9, wherein the processor is configured to multiply the resistance by a square of the value of the one of the parameters to determine the amount of RF power loss.

15. 10. The controller of claim 9, wherein the processor is configured to adjust the set point of operation of the RF generator to control the RF generator to operate at a second set point; To iterate between obtaining the one or more further values, determining the one or more further amounts of RF power loss, and adjusting the set point of operation of the RF generator, the controller: obtaining a second value of the one of the plurality of parameters associated with the component of the plasma system; determining a second RF power dissipation amount from the resistance and the second value of the one of the plurality of parameters; configured to adjust the set point of operation of the RF generator based on the second amount of RF power loss; The processor is configured to adjust the set point of operation of the RF generator based on the second amount of RF power loss to control the RF generator to operate at a third set point.

16. The controller of claim 9 , wherein to adjust the set point, the processor is configured to sum the amount of RF power loss and the set point.

17. 1. A plasma system for compensating for radio frequency (RF) power losses, comprising: a radio frequency (RF) generator configured to generate an RF signal; an impedance matching circuit connected to the RF generator to receive the RF signal; a computer connected to the RF generator; Equipped with The computer includes: obtaining a plurality of measurements of a plurality of parameters associated with components of the plasma system; determining a resistance associated with the component of the plasma system from the plurality of measurements of the plurality of parameters; obtaining a value of a parameter of the plurality of parameters associated with the component of the plasma system; determining an amount of the RF power loss associated with the component of the plasma system from the resistance and the value of the one of the plurality of parameters; adjusting an operating set point of the RF generator based on the amount of RF power loss; and repeating determining one or more additional values ​​for the one parameter of the plurality of parameters, determining one or more additional amounts of the RF power loss, and adjusting the set point of operation of the RF generator until the amount of adjustment applied to the set point compensates for the RF power loss.

18. 20. The plasma system of claim 17, wherein the computer determines that the amount of adjustment being applied to the set point is compensating for the RF power loss when a plurality of RF power loss amounts each fall within a predetermined range.

19. 20. The plasma system of claim 17, wherein the computer adjusts the set point of operation of the RF generator to control the RF generator to operate at a second set point; To iterate between obtaining the one or more additional values, determining the one or more additional amounts of RF power loss, and adjusting the set point of operation of the RF generator, the computer: obtaining a second value of the one of the plurality of parameters associated with the component of the plasma system; determining a second RF power dissipation amount from the resistance and the second value of the one of the plurality of parameters; configured to adjust the set point of operation of the RF generator based on the second amount of RF power loss; The computer is configured to adjust the set point of operation of the RF generator based on the second amount of RF power loss to control the RF generator to operate at a third set point.

20. 20. The plasma system of claim 17, wherein the computer determines that the amount of adjustment being applied to the set point is compensating for the RF power losses when a plurality of RF power loss amounts fall within a predetermined range of each other.

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