Closed-loop multi-output radio frequency (RF) matching

Abstract

To provide a device and a method for executing control of a closed-loop multi-output of radio frequency (RF) matching in a semiconductor wafer manufacturing process.SOLUTION: In a device for supplying a signal to a station of a process chamber for executing a semiconductor manufacturing process, a plurality of signal generators generate signals with a first frequency and a second frequency. A phase-voltage-current detection circuit 215 as a measurement circuit measures a voltage standing wave ratio (VSWR). A matching reflection optimization circuit 220 adjusts an invalid component according to an output signal from the measurement circuit.SELECTED DRAWING: Figure 2

Description

[Background technology]

[0001] The background and background discussion contained herein is provided solely for the purpose of generally presenting the content of the present disclosure. Much of the present disclosure presents work by the inventors, and merely because such work is described in the Background section or presented as content elsewhere herein does not mean that such work is admitted to be prior art.

[0002] The fabrication of semiconductor wafers utilized to form integrated circuits may include numerous and diverse processing steps. In certain processing steps, which may occur after various materials have been deposited on a semiconductor wafer, material may be etched away so that additional materials, such as metals, can be deposited. Such deposition may include the formation of conductive traces, transistor gates, vias, circuit elements, and the like. However, in at least some instances, semiconductor manufacturing processes involving plasma-based and / or etch plasma-enhanced atomic layer deposition, uncontrolled process variations, and the like, may result in reduced yields, increased costs, unnecessary redesign of semiconductor layouts and masks, and the like. Thus, techniques to improve control of plasma-based wafer etching and / or plasma-enhanced atomic layer deposition continue to be an active area of ​​research. [Brief description of the drawings]

[0003] [Figure 1A] FIG. 1A illustrates a substrate processing apparatus for depositing films on semiconductor substrates using any number of processes.

[0004] [Figure 1B] FIG. 1B is a block diagram illustrating various components of a system utilized to perform a semiconductor manufacturing process, according to one embodiment.

[0005] [Diagram 2]FIG. 2 is a block diagram illustrating various components of a closed loop multiple output radio frequency (RF) matching process used in performing a semiconductor manufacturing process, according to one embodiment.

[0006] [Diagram 3] FIG. 3 is a diagram illustrating various circuit elements utilized in a closed loop multiple output RF matching process used in performing a semiconductor manufacturing process, according to one embodiment.

[0007] [Figure 4] FIG. 4 is a diagram illustrating circuit elements utilized to perform match reflection optimization for a closed loop multiple output RF matching process used in performing a semiconductor manufacturing process, according to one embodiment.

[0008] [Diagram 5] FIG. 5 is a diagram illustrating circuit elements used to implement RF power control in a closed loop multiple output RF matching process, according to one embodiment.

[0009] [Figure 6] FIG. 6 is a diagram illustrating circuit elements used to provide RF isolation and filtering to a closed loop multiple output RF matching process used in performing a semiconductor manufacturing process, according to one embodiment.

[0010] [Figure 7] FIG. 7 is a diagram illustrating circuit elements used to perform matching and / or impedance transformation in a closed loop multiple output RF matching process used in performing a semiconductor manufacturing process, according to one embodiment.

[0011] [Figure 8] FIG. 8 is a flow chart of a method for closed loop RF matching, according to one embodiment.

[0012] [Figure 9] FIG. 9 shows a schematic diagram of one embodiment of a multi-station processing tool. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] In certain embodiments, closed-loop multi-output radio frequency (RF) matching may be utilized in various semiconductor manufacturing processes, such as plasma-based wafer fabrication. Closed-loop multi-output RF matching may provide the ability to provide RF power to one or more stations of a process chamber in a manner that is dynamically adjustable to various loads presented by the stations of the process chamber. Such dynamic adjustments provide real-time capability to closely match the impedance of the load presented by the plasma in the station to the impedance source of one or more RF power generators, even as the loads and the like vary during the progress of the manufacturing process. Thus, the RF provided from the individual stations may be dynamically increased, while the RF power reflected from the RF power generators may be decreased and / or minimized. Certain embodiments may be utilized in several wafer fabrication processes, such as various plasma-enhanced atomic layer deposition (ALD) processes, various plasma-enhanced chemical vapor deposition (CVD) processes, or may be utilized on the fly during a single deposition process. In certain embodiments, the RF power matching network utilizes a simplified circuit topology to accommodate load variations at any signal frequency, such as 400 kHz and 27.12 MHz. However, in other embodiments, the RF power matching network may operate at any signal frequency, including relatively low frequencies (e.g., between about 50 kHz and about 1 MHz), as well as higher signal frequencies (e.g., between about 10 MHz and about 100 MHz).

[0014] It should be noted that while certain embodiments described herein may show and / or describe closed loop multiple output radio frequency matching for use with four process chamber stations, other embodiments may utilize a fewer number of process chamber stations, such as one station, two stations, or three stations. In other embodiments, closed loop multiple output radio frequency matching may be utilized with a greater number of process chamber stations, such as five, six, seven, eight, ten, twelve, or any other number of process chamber stations.

[0015] The fabrication of semiconductor devices typically involves depositing one or more thin films on planar or non-planar substrates in an integrated manufacturing process. In some aspects of the integrated process, it may be beneficial to deposit a thin film that conforms to the topography of the substrate. One type of reaction that may be beneficial in some cases involves chemical vapor deposition (CVD). In a typical CVD process, gas phase reactants are simultaneously introduced into a station of a reaction chamber to cause a gas phase reaction. The reaction products are deposited on the surface of the substrate. The reaction may be driven by a plasma, in which case the process may be referred to as a plasma enhanced chemical vapor deposition (PECVD) reaction. As used herein, the term CVD is intended to include PECVD unless otherwise indicated. CVD processes have certain drawbacks that may render them less suitable in some contexts. For example, mass transfer limitations of CVD gas phase reactions may lead to a "bread loafing" deposition effect, which exhibits thicker deposition on top surfaces (e.g., top surfaces of a gate stack) and thinner deposition on concave surfaces (e.g., bottom corners of a gate stack). Additionally, because some dies may have regions with different device densities, mass transfer effects across the substrate surface can result in thickness variations within the die and within the wafer. These thickness variations can result in over-etching in some areas and under-etching in others, reducing device performance and die yield. Another problem with CVD processes is that they often cannot form conformal films over high aspect ratio features. This problem becomes more problematic as devices become smaller. These and other disadvantages of specific embodiments of wafer fabrication processes are discussed with respect to FIGS. 1A and 1B.

[0016] In another example, some deposition processes include multiple film deposition cycles, each producing a distinct film thickness. For example, atomic layer deposition (ALD) may be intended to include multiple cycles of deposition by using thin film layers in successive iterations. In the semiconductor industry, the ability to deposit conformal thin films (films of material that have uniform thickness relative to the shape of the underlying structure, even if non-planar) continues to gain importance as device and feature sizes shrink and 3D device structures become more prevalent in integrated circuit (IC) designs. ALD is a film formation technique that is well suited to the deposition of conformal films due to the fact that one cycle of ALD deposits only a thin film of a single material, the thickness being limited by the amount of reactants of one or more precursor films that may adsorb (i.e., form a limiting adsorbed layer) on the substrate surface prior to the film-forming chemical reaction itself. Multiple ALD cycles may then be used to form a film of the desired thickness, with each layer being thin and conformal, such that the resulting film will substantially match the shape of the underlying device structure. In certain embodiments, each ALD cycle includes the following steps:

[0017] Exposing a substrate surface to a first precursor.

[0018] Cleaning the reaction chamber in which the substrate is located.

[0019] Activating a reaction at the substrate surface, typically using a plasma and / or a second precursor.

[0020] Cleaning the reaction chamber in which the substrate is located.

[0021] The duration of each ALD cycle may typically be less than 25 seconds, or less than 10 seconds, or less than 5 seconds. The plasma exposure step (or steps) of an ALD cycle may be of short duration, such as 1 second or less in duration.

[0022] FIG. 1A shows a substrate processing apparatus for depositing a film on a semiconductor substrate using any number of processes. The apparatus 100 of FIG. 1A utilizes a single process station 102 of a process chamber with a single substrate holder 108 (e.g., pedestal) within an interior volume that can be maintained under vacuum by a vacuum pump 118. Also fluidly coupled to the process chamber for supplying (for example) film precursors, carrier and / or purge gases and / or process gases, secondary reactants, etc. is a gas supply system 101 and a showerhead 106. An apparatus for generating plasma in the process chamber is also shown in FIG. 1A. The apparatus shown generally in FIG. 1 may be specifically adapted for performing plasma enhanced CVD.

[0023] For simplicity, the processing apparatus 100 is shown as a stand-alone process station (102) in a process chamber for maintaining a low pressure environment. However, as described herein, it will be appreciated that multiple process stations may be included within a common process tool environment, e.g., a common reaction chamber. For example, FIG. 1B illustrates an embodiment of a multi-station processing tool, which is described in more detail below. Additionally, it will be appreciated that in some embodiments, one or more hardware parameters of the processing apparatus 100, including those described in more detail herein, may be programmatically adjusted by one or more system controllers.

[0024] The process chamber stations 102 are in fluid communication with a gas delivery system 101 for supplying process gases, which may include liquids and / or gases, to a distribution showerhead 106. The gas delivery system 101 includes a mixing vessel 104 for mixing and / or conditioning the process gases for delivery to the showerhead 106. One or more mixing vessel inlet valves 120 may control the introduction of process gases into the mixing vessel 104.

[0025] Some reactants may be stored in liquid form prior to vaporization and delivery to the subsequent process chamber station 102. The embodiment of FIG. 1A includes a vaporization point 103 for vaporizing the liquid reactants delivered to the mixing vessel 104. In some embodiments, the vaporization point 103 may be a heated liquid injection module. In other embodiments, the vaporization point 103 may be a heated vaporizer. In still other embodiments, the vaporization point 103 may be removed from the process station. In some embodiments, a liquid flow controller (LFC) upstream of the vaporization point 103 may be provided to control the mass flow rate of liquid for vaporization and delivery to the process station 102.

[0026] The showerhead 106 distributes process gases and / or reactants (e.g., film precursors) toward the substrate 112 at the process stations, the flow of which is controlled by one or more valves (e.g., valves 120, 120A, 105) upstream from the showerhead. In the embodiment shown in FIG. 1A, the substrate 112 is shown positioned below the showerhead 106 and resting on a pedestal 108. The showerhead 106 may have any suitable shape and any suitable number and arrangement of ports for distributing process gases to the substrate 112. In some embodiments with more than one station, the gas delivery system 101 includes valves or other flow control structures upstream from the showerhead that allow independent control of the flow of process gases and / or reactants to each station, such that gases cannot flow to one station and not another. Additionally, the gas supply system 101 may be configured to independently control the process gases and / or reactants supplied to each station in a multi-station apparatus such that the gas compositions supplied to different stations are different, e.g., partial pressures of gas components may be varied between stations simultaneously.

[0027] Volume 107 is located below the showerhead 106. In some embodiments, pedestal 108 may be raised or lowered to expose substrate 112 to volume 107 and / or to change the volume of volume 107. Optionally, pedestal 108 may be lowered and / or raised during portions of the deposition process to adjust process pressure, reactant concentrations, etc. within volume 107.

[0028] In FIG. 1A, the showerhead 106 and pedestal 108 are electrically coupled to a radio frequency power source 114 and a matching network 116 to provide power to the plasma generator. In some implementations, the plasma energy may be controlled (e.g., via a system controller having suitable machine-readable instructions and / or control logic) by controlling one or more of the process station pressure, gas concentration, RF power source, etc. For example, the radio frequency power source 114 and the matching network 116 may be operated at any suitable power to form a plasma having a desired composition of radical species. Similarly, the RF power source 114 may provide RF power of any suitable frequency, or group of frequencies, and power.

[0029] In some implementations, plasma ignition and maintenance conditions are controlled with suitable machine-readable instructions in a system controller capable of providing control instructions via a sequence of suitable hardware and / or input / output control (IOC) instructions. In one example, instructions for setting plasma conditions for plasma ignition or maintenance are provided in the form of a plasma activation recipe of a process recipe. In some cases, a process recipe may be sequentially arranged such that all instructions for a process are executed simultaneously with that process. In some implementations, instructions for setting one or more plasma parameters may be included in a recipe preceding a plasma process. For example, a first recipe may include instructions for setting flow rates of an inert gas (e.g., helium) and / or a reactive gas, instructions for setting a plasma generator to a power setpoint, and a time delay instruction for the first recipe. A subsequent second recipe may include instructions for enabling the plasma generator and a time delay instruction for the second recipe. A third recipe may include instructions for disabling the plasma generator and a time delay instruction for the third recipe. It will be appreciated that these recipes may be further subdivided and / or repeated in any suitable manner within the scope of the present disclosure.

[0030] In some deposition processes, the plasma strikes last for commands of several seconds or more in duration. In certain implementations described herein, much shorter plasma strikes may be applied during a processing cycle. These may be commands of less than 50 milliseconds, such as 25 milliseconds.

[0031] FIG. 1B is a block diagram illustrating various components of a system utilized to perform a semiconductor manufacturing process, according to one embodiment 151. In FIG. 1B, RF signal generators 155 and 160 are utilized to generate excitation signals that may result in the formation of plasma in stations 102A, 102B, 102C, and 102D of a process chamber. Stations 102A, 102B, 102C, and 102D may correspond to stations of a semiconductor process chamber, as previously described with reference to FIG. 1A. Thus, in the embodiment of FIG. 1B, RF signal generator 155 may generate a relatively low frequency signal, such as a signal of about 400 kHz, while RF signal generator 160 generates a relatively high frequency signal, such as a signal of about 27.12 MHz. However, it should be noted that these represent merely exemplary frequencies. In other embodiments, different radio frequencies may be generated, and the embodiments are not limited to 400 kHz and 27.12 MHz signals. For example, in one particular example, the relatively low frequency may correspond to a frequency between 360 kHz and 440 kHz, and in another example, the relatively high frequency may correspond to a frequency between 26.5 MHz and 27.5 MHz.

[0032] In FIG. 1B, the RF transmission line connecting signal generator 155 to low frequency matching network 158 and the radio frequency transmission line connecting signal generator 160 to high frequency matching network 163 may include a characteristic impedance of 50 ohms. However, other implementations may utilize transmission lines having different characteristic impedances, such as 70 ohms, 300 ohms, etc. In the implementation of FIG. 1B, low frequency matching network 158 and high frequency matching network 163 operate to match the load presented by power divider 170 to the output impedance of signal generator 155 and signal generator 160 (respectively). Such matching provides the ability to couple maximum power transfer from radio frequency signal generators 155 and 160 to power divider 170. Thus, maximum power can be transferred from signal generators 155 and 160 to power divider 170 even when power divider 170 presents a high reactive load (e.g., a complex impedance with a relatively small real component and a large reactive component). Matching networks 158 and 163 may utilize various reactive components, such as inductors and / or capacitors, which operate to compensate for the high reactive load that may be presented by power divider 170.

[0033] In certain implementations, the components of the matching network 158 / 163 may be arranged to match a particular load presented by the low and high frequency input ports of the power divider 170, and may thereby operate to provide plasma generating power via the output ports 171, 172, 173, and 174. However, during (for example) a plasma based etch operation or other plasma based process, loads such as reactive loads presented by the formation of plasma in the stations 102A, 102B, 102C, and 102D of the process chamber may begin to change or fluctuate. Thus, for example, during the initial period of plasma generation (e.g., the initial 30-60 seconds), the output signal amplitudes from the ports 171-174 may correspond to substantially equal amounts. However, as the plasma generation progresses, the output signal amplitudes from the ports 171-174 may begin to differ. Such differences may result from changes in the reactive loads presented by the stations 102A-102D of the process chamber. Thus, in some examples, in response to changes in the reactive load presented by the process chamber stations 102A-102D, the actual power coupled out of the power divider ports 171-174 may vary by values ​​ranging from 0.0% to 25.0%. Additionally, the RF power flow to the stations can be set to 0.0, or some other negligible amount, by entering 0.0 watts as the set point. Alternatively, the capacitance of the variable capacitor may be adjusted to a value that results in a current flow close to or about 0.0 amps.

[0034] 1B may therefore be classified as an "open loop" plasma generation system in that it may be difficult to ensure a constant, uniform power transfer from power divider 170 to stations 102A-102D during plasma generation operations. Thus, without additional controls, such as controls that operate to provide real-time, closed-loop adjustment of reactive components in low frequency matching network 158 and high frequency matching network 163 in response to variations in the reactive loads presented by stations 102A-102D, undesirable results may occur. Such results may include, for example, under-etching, where insufficient material is removed from the semiconductor wafer, and over-etching, where an excessive amount of material is removed from the semiconductor wafer. In some instances, such under-etching and / or over-etching may result in the need to scrap etched semiconductor wafers, resulting in increased costs, schedule delays, and the like.

[0035] FIG. 2 is a block diagram illustrating various components of a closed loop multiple output radio frequency (RF) matching process used to perform a semiconductor manufacturing process, according to one embodiment 200. The embodiment of FIG. 2 may lead to improved control of the power transferred from the low frequency signal generator and the high frequency signal generator to the process chamber. Such improved control may be provided by power flow sensing, which may operate to adjust or tune the values ​​of reactive components of the matching network in a manner that can compensate in real time for changes in the reactive impedance presented by the process chamber. Accordingly, changes in the reactive impedance presented by the process chamber, which may change during the plasma excitation process, are compensated for to allow maximum power transfer from the signal generator to the process chamber. Additionally, the power flow sensing, which may be achieved, for example, by using one or more phase sensitive voltmeters, may operate in a multi-channel environment, such as the environment of FIG. 1B, where the power flow may remain substantially equal across the power divider output ports 171, 172, 173, and 174. Moreover, such techniques may be extended to power splitters having six output ports, eight output ports, ten output ports, or any other number of output ports, without substantial limitation, and may be coupled to multiple stations of one process chamber, such as coupling to six stations, eight stations, ten stations, or any number of stations. Of course, the impedance presented by four output ports, such as output ports 171, 172, 173, and 174 of FIG. 1B, may be scaled upward to present a parallel combination of about 50 ohms. For example, in the case of a power splitter with four output ports, each output port may be matched to a 200 ohm load to present a 50 ohm load at a single input port. In another example, in the case of a power splitter with eight output ports, each output port may be matched to a 400 ohm load to present a 50 ohm load at a single input port.

[0036] In the embodiment of Figure 2, the plasma excitation process may be performed in stations 102A, 102B, 102C, and 102N of the process chamber. Thus, although only four stations (102A-102N) are shown, claimed subject matter is not limited to any particular number of stations in the process chamber. An embodiment may include two stations, three stations, five stations, eight stations, etc.

[0037] In FIG. 2, the signal generator 205 may represent a composite signal generator, such as a signal generator generating two different frequencies, such as a low frequency (e.g., 400.0 kHz) and a high frequency (e.g., 27.12 MHz). Thus, the signal generator 205 may be implemented utilizing two or more signal generators, the outputs of which may be combined in a power combiner, such as a two-way Wilkinson power combiner. The signal generator 205 may include an output impedance of 50 ohms, which may be coupled to a transmission line 210, which may include a characteristic impedance of 50 ohms. The transmission line 210 may be coupled to a phase / voltage / current sensing circuit 215, which may operate to provide a feedback signal in response to an impedance mismatch between the transmission line 210 and the match reflection optimizer 220. For example, the phase / voltage / current sensing circuit 215 may provide a signal of approximately 50 ohms to the match reflection optimizer 220 when the voltage standing wave ratio (VSWR) increases beyond a threshold value. Thus, in some embodiments, if the phase / voltage / current sensing circuit 215 measures a VSWR that increases from, for example, 1.0:1 to 1.15:1, the reactive components of the matched reflection optimizer 220 may be modified to reduce the measured VSWR to a smaller value, such as 1.10:1 or less. However, it should be noted that the measured VSWR threshold at which the reactive components of the matched reflection optimizer 220 should be modified may be determined according to a desired application, and the embodiments are not limited to any particular VSWR threshold or range of VSWR thresholds. Thus, in certain embodiments, for example, if a VSWR greater than 1.10:1 is measured, the reactive components of the matched reflection optimizer 220 may be adjusted to reduce the measured VSWR to 1.10:1. However, it should be noted that in certain implementations, adjusting the reactive components of the matched reflection optimizer 220 in response to relatively small changes in the measured VSWR, e.g., resulting in a VSWR of less than 1.05:1, may result in over-adjusting the reactive components of the matched reflection optimizer 220, potentially reducing the useful life of the reactive components. Various circuit topologies may be utilized for the matched reflection optimizer 220, as shown in FIG. 3 herein.

[0038] In FIG. 2, a number of RF power control circuits 225A-225N are shown coupled from an output port of the match reflection optimizer 220 to an input port of the isolation RF filters 230A-230N. In certain embodiments, the RF power control circuits 225 operate to provide maximum power transfer between the match reflection optimizer 220 and each of the process chamber stations 102A-102N. In certain embodiments, the RF power control circuit 225A includes an adjustable reactive component (e.g., a capacitor) that provides maximum power transfer from the output port of the match reflection optimizer 220 and the input port of the process chamber stations 102A-102N in a manner similar to the match reflection optimizer 220. In the embodiment of FIG. 2, such adjustment of one or more reactive components of the RF power control circuits 225A-225N may be provided in response to a second measurement of a phase sense voltage, such as by the phase / voltage / current sense circuit 235A. Thus, in certain implementations, for example, in response to phase / voltage / current sensing circuit 235A measuring an increase in VSWR at the input port of station 102, sensing circuit 235A may adjust reactive components of RF power control circuit 225A to reduce the VSWR, thereby improving power transfer between RF power control circuit 225A and station 102A. Similarly, phase / voltage / current sensing circuit 235B may operate to adjust one or more reactive components of RF power control circuit 225B. Similarly, phase / voltage / current sensing circuit 235C may operate to adjust one or more reactive components of RF power control circuit 225C. Similarly, phase / voltage / current sensing circuit 235N may operate to adjust one or more reactive components of RF power control circuit 225N.

[0039] The isolating RF filters 230A-230N operate to provide decoupling between high frequency sources (e.g., 27.12 MHz) and low frequency sources (e.g., 400 kHz sources), while allowing both signals to be present at the stations 102A-102N with sufficient amplitude. Thus, as can be seen with reference to Figure 7, although both low frequencies (e.g., 400 kHz) as well as high frequencies (e.g., 27.12 MHz) may be interacted within a particular station, RF notch filters may be utilized to substantially isolate the low frequency signals from the high frequency signals, while high pass filters may be utilized to substantially isolate the high frequency signals from the low frequency signals.

[0040] Figure 3 is a diagram illustrating various circuit elements utilized in a closed loop multiple output radio frequency matching process used to perform a plasma excitation process, according to one embodiment 300. Note that for purposes of clarity of illustration, only a subset of the components of Figure 2 are shown in Figure 3. However, it will be appreciated that, for example, any number of RF power control circuits (e.g., 225A, 225B), isolation RF filters (e.g., 230A, 230B), phase / voltage / current sensing circuits (e.g., 235A, 235B), and stations (e.g., 102A, 102B) may be utilized.

[0041] In FIG. 3, the match reflection optimizer 220 includes a variable capacitor C220 as well as an inductor L220. In the embodiment of FIG. 3, the inductor L220 represents a static component, having a value selected to provide a range of admittances that can be presented by the combination of L220 and C220 connected in series. In certain embodiments, C220 represents a variable capacitor having a value controllable via a remote signal, such as a signal from the phase / voltage / current sense circuit 215. Thus, in response to the phase / voltage / current sense circuit 215 measuring an increase in inductance presented by the combination of the RF power control circuits 225A-225N (e.g., via measuring the VSWR), the value of the capacitance presented by C220 may be adjusted to present sufficient admittance to return the measured VSWR to a value below a predetermined threshold (e.g., 1.15:1, 1.10:1, etc.). Such adjustment of the capacitor C220 results in an increase in power transfer from the signal generator 205 to the RF power control circuit (e.g., 225A).

[0042] The RF power control circuit 225A may further include a series impedance represented by C225A and inductor L225A. Inductor L225A may represent a static component having a value selected to provide a range of impedances that can be represented by the combination of C225A and L225A. In a particular embodiment, C225A may represent a variable capacitor having a value controllable via a remote signal, such as a signal from the phase / voltage / current sensing circuit 235A. Thus, in response to the phase / voltage / current sensing circuit 235A measuring the change in the impedance of station 102A, capacitor C225A may be adjusted to provide maximum power transfer between the matched reflection optimizer 220 and stations 102A and 102B.

[0043] 4 is a diagram illustrating circuit elements utilized to perform match reflection optimization for a closed loop multiple output radio frequency matching process used to perform a semiconductor manufacturing process, according to one embodiment 400. As previously described with reference to FIG. 3, the matching circuit reflection optimizer 220 may include a shunt circuit utilizing relatively fixed inductance and variable capacitor values ​​to provide admittance, which may operate to maximize power transfer from the signal generator 205 to the RF power control circuit 225A. However, it will be appreciated that while a matching reflection optimizer circuit such as circuit 220 may be particularly suitable for matching at higher frequencies, such as 27.12 MHz, other circuit topologies, such as π-type matching circuit 420, may operate to provide matching at somewhat lower frequencies, such as 400 kHz. Additionally, under other circumstances, a T-type matching circuit, such as circuit 320, may be utilized, such as where a series impedance may be utilized to lower the VSWR.

[0044] FIG. 5 illustrates circuit elements used to implement RF power control in a closed loop multiple output radio frequency matching process according to one embodiment 500. The embodiment of FIG. 5 may be consistent with the embodiment of FIG. 4, in which various circuit topologies may be utilized according to the frequency at which impedance matching is to be achieved (e.g., 400 kHz or 27.12 MHz). In many instances, it is believed that a series circuit, such as series circuit 225A with adjustable capacitance C225A, may operate to bring the VSWR measured by phase / voltage / current sensing circuit 235A below a threshold value. However, in other instances, it may be advantageous to utilize a parallel circuit, such as parallel circuit 325, to reduce or otherwise modify the VSWR measured by phase / voltage / current sensing circuit 235A. In still other instances, it may be advantageous to utilize a shunt circuit, such as shunt circuit 425, to reduce or otherwise modify the VSWR measured by phase / voltage / current sensing circuit 235A.

[0045] 6 illustrates circuit elements used to provide RF isolation and filtering for a closed loop multiple output radio frequency matching process used to perform a semiconductor manufacturing process, according to one embodiment 600. As in FIGS. 4 and 5, various circuit topologies may be present to provide decoupling between a high frequency source (e.g., 27.12 MHz) and a low frequency source (e.g., 400 kHz source) while allowing both signals, and sufficient amplitude, to be present at stations 102A-102N of the process chamber. Thus, a circuit designer may utilize high pass filter 230, low pass filter 330, notch filter 435, and / or band pass filter 535 to achieve sufficient isolation (such as between 25.0 dB and 35.0 dB isolation).

[0046] FIG. 7 illustrates circuit elements used to perform matching and / or impedance transformation in a closed loop multiple output radio frequency matching process used to perform a semiconductor manufacturing process, according to one embodiment 700. It may be appreciated that the purpose of the circuit elements in FIG. 7 may be to couple signals from high frequency generator 160 and low frequency generator 155 to a station, such as station 102A. As previously discussed, stations for performing plasma-based wafer manufacturing processes (or other types of semiconductor manufacturing processes) may present impedances having only a small real portion with a relatively high reactive (or imaginary) portion. Thus, in certain embodiments, one purpose of low frequency matching network 158 and high frequency matching network 163 is to transform the impedance of a process station (e.g., stations 102-102N of a process chamber) such that such impedance is viewed similarly to a load of at least 50 ohms. In an embodiment, such impedance transformation enables power transfer to a highly reactive (e.g., inductive / capacitive) load between the signal generator and the transmission line, which has a characteristic impedance of 50 ohms.

[0047] However, it may also be appreciated that in at least certain implementations, isolating high frequency signals from low frequency signals may be problematic, and in certain implementations, if such signals are not isolated (or decoupled, for example, by at least 25 dB to 40 dB), such mutual coupling may interfere with the ability of the signal generator to generate a suitable radio frequency signal.

[0048] Thus, in FIG. 7, a shunt network 710 may be utilized to filter low frequency components from the output signal port of the HF signal generator 160. Thus, the values ​​of HF_L1 and HF_L2, shown in parallel in the shunt network 710, may be selected to shunt low frequency signals, such as a 400 kHz signal, to a local ground. Furthermore, the capacitor HF_C1 may also be selected to present an open circuit (or at least a relatively high impedance) to the low frequency signal 730 that may be coupled from the low frequency matching network 158. Thus, in one embodiment, the signal 730 may only be weakly coupled (as evidenced by the low amplitude signal 735) through the filtering action of the capacitor HF_C1. However, as shown in FIG. 7, before hitting the capacitor HF_C, the signal 730 may be coupled to station 1 through a VI probe.

[0049] Additionally, the high frequency signal from HF matching network 163, as shown by waveform 720, may be significantly attenuated by notch filter (NF) 715, such as by an amount between 25-40 dB. Thus, as shown by waveform 725, the high frequency waveform 720 may be significantly attenuated. However, the high frequency components may be able to couple to station 102A via VI probe 717. Thus, as shown in FIG. 7, at node 728, both the high frequency waveform 720 and the low frequency signal 730 may be able to couple to station 102A via VI probe 717.

[0050] While Figure 7 shows a single signal path associated with station 102A, including HF_C1, notch filter (NF) 715, and VI probe 717, it is contemplated that in some embodiments, a separate signal path including a separate notch filter and separate VI probe may be replicated in conjunction with additional process stations, such as stations 102B, 102C, and 102D, as shown in Figure 2. Similarly, while Figure 7 shows only a single signal path for low frequency matching network 158, including signal coupling through a low pass filter and impedance transformation network 740, it is contemplated that in some embodiments, it may include separate signal paths, such as one signal path for each of process stations 102A, 102B, 102C, and 102D.

[0051] Figure 8 is a flow chart for a method of closed loop RF matching, according to one embodiment. The method of Figure 8 begins at 810 and includes measuring a voltage standing wave ratio (VSWR) at an input port of a power divider. The method continues at 820 and includes adjusting a value of a reactive component of a matched reflection optimizer in response to the measured VSWR, where adjusting the reactive component results in a second VSWR that is lower than the first threshold.

[0052] At 820, the reactive component may correspond to a variable capacitor or may correspond to a variable inductor. Adjusting the reactive component may result in a second VSWR that is less than 1.15:1. However, in some implementations, it may be desirable to reduce the second VSWR to a value less than 1.15:1 or less, such as less than 1.25:1, less than 1.20:1, less than 1.10:1, or less than 1.05:1. The VSWR may be measured at any number of signal frequencies, such as about 400 kHz, between 360 kHz and 440 kHz, or other frequencies between about 50 kHz and 1 MHz. The VSWR may also be measured at about 27.12 MHz, between about 26.5 MHz and about 27.5 MHz, or any other signal frequency between about 1 MHz and 50 MHz. The VSWR measurements may be taken at an input port of one or more input ports corresponding to a station of the process chamber.

[0053] One or more process stations may be included in a multi-station processing tool. Thus, the figure shows a schematic diagram of one embodiment of a multi-station processing tool 900. The tool 900 may use a single substrate processing chamber 914 that includes multiple substrate processing stations, each of which may be used to perform processing operations on a substrate held on a wafer holder, e.g., a pedestal, at that process station. In this particular embodiment, the multi-station substrate processing apparatus 900 is shown having four process stations 102A, 102B, 102C, and 102D. Other similar multi-station processing apparatus may have more or fewer process stations depending on the implementation and, e.g., the desired hierarchy of parallel wafer processing, size / space constraints, cost constraints, etc. Also shown in FIG. 2 is a substrate handler robot 906 and a controller 950.

[0054] As shown in FIG. 9, the multi-station processing tool 900 has a substrate loading port 920 and a robot 906 configured to move a substrate from a cassette loaded by a pod 908 through the loading port 920 into a process chamber 914 and onto one of four stations 102A, 102B, 102C, and 102D.

[0055] The depicted process chamber 914 shown in FIG. 9 includes four process stations 102A, 102B, 102C, and 102D. RF power is generated in an RF power system 913 and distributed to each of the stations 102A, 102B, 102C, and 102D. The RF power system may include one or more RF power sources, e.g., high frequency (HFRF) and low frequency (LFRF) power sources, impedance matching modules, and filters. In certain implementations, the power sources may be limited to only high frequency or low frequency sources. The distribution system of the RF power system may be symmetrical with respect to the reactor and may have a high impedance. This symmetry and impedance result in approximately equal amounts of power being delivered to each station. In some implementations, the RF power system may be configured to deliver power to each station independently.

[0056] 9 also illustrates one embodiment of a substrate transport apparatus 990 for transporting substrates between process stations 102A, 102B, 102C, and 102D within process chamber 914. It will be appreciated that any suitable substrate transport apparatus may be used. Non-limiting examples include a wafer carousel and a wafer handling robot. System Controller

[0057] 9 also shows one embodiment of a system controller 950 used to control the process conditions and hardware states of the process tool 900. The system controller 950 may include one or more memory devices 956, one or more mass memory devices 954, and one or more processors 952. The processor 952 may include a CPU or computer, analog and / or digital input / output connections, stepper motor controller boards, etc.

[0058] In some implementations, the system controller 950 controls all operations of the process tool 900. The system controller 950 executes system control software 958, which is stored on mass storage device 954, loaded into storage device 956, and executed by processor 952. The system control software 958 may include instructions for controlling the timing, mixture of gases, chamber and / or station pressure, chamber and / or station temperature, wafer temperature, target power levels, RF power levels, RF exposure time, substrate pedestal, chuck and / or susceptor position, number of cycles performed on one or more substrates, and other parameters of the particular processes performed by the process tool 900. These programmed processes may include various types of processes, including, but not limited to, processes related to determining the amount of build-up on surfaces inside the chamber, processes related to deposition of films on substrates including cycle numbers, determining and obtaining compensated cycle numbers, and processes related to cleaning of the chamber. The system control software 958 may be configured in any suitable manner. For example, various process tool component subroutines or control objects may be written to control the operation of process tool components necessary to perform various process tool processes. The system control software 958 may be coded in any suitable computer-readable programming language.

[0059] In some implementations, the system control software 958 may include input / output control (IOC) sequence instructions for controlling the various parameters described above. For example, deposition on a substrate and each phase of a deposition cycle may include one or more instructions for execution by the system controller 950. Instructions for setting process conditions for an ALD / CFD deposition phase process may be included in a corresponding ALD / CFD deposition phase recipe. In some implementations, the phase recipes may be sequenced such that all instructions for a phase process are executed simultaneously with that phase process.

[0060] In some implementations, other computer software and / or programs stored on the mass storage device 954 and / or storage device 956 associated with the system controller 950 may be used. Examples of programs or sections of programs for this purpose include a substrate positioning program, a process gas control program, a pressure control program, a heater control program, and a plasma control program.

[0061] The substrate positioning program may include program code for process tool components used to load the substrate onto the pedestal 918 as well as control the spacing between the substrate and other parts of the process tool 900. The positioning program may include instructions for properly moving the substrate in and out of reaction chambers required for depositing films on the substrate and cleaning chambers.

[0062] The process gas control program may include code for controlling gas composition and flow rates, and optionally code for flowing gases to one or more process stations prior to deposition to stabilize pressure within the process stations. In some embodiments, the process gas control program includes instructions for introducing gases during formation of a film on a substrate within a reaction chamber. This may include introducing different cycles of gases for one or more substrates within a batch of substrates.

[0063] The pressure control program may include code for controlling the pressure in the process station, for example, by adjusting a throttle valve in the exhaust system of the process station, gas flow to the process station, etc. The pressure control program may include instructions for maintaining the same pressure during deposition at different cycle numbers on one or more substrates during processing of a batch.

[0064] The heater control program may include code for controlling the current to a heating unit used to heat the substrate, or the heater control program may control the supply of a heat carrier gas (such as helium) to the substrate.

[0065] The plasma control program may include code for setting RF power levels, frequencies, and exposure times for one or more process stations according to embodiments herein. In some embodiments, the plasma control program may include instructions for using the same RF power level and / or frequency and / or exposure time during deposition of different cycles on one or more substrates during processing of a batch.

[0066] In some implementations, there may be a user interface associated with the system controller 950. The user interface may include a display screen, a graphical software representation of equipment and / or process conditions, and user input devices such as a pointing device, keyboard, touch screen, microphone, etc.

[0067] In some implementations, the parameters adjusted by the system controller 950 may relate to process conditions. Non-limiting examples include process gas composition and flow rates, temperature, pressure, plasma conditions (such as RF bias power levels and exposure times), etc. These parameters may be provided to a user in the form of a recipe or may be entered utilizing a user interface. A recipe for an entire batch of substrates may include a total number of compensated cycles for one or more substrates in the batch to account for thickness trends while processing the batch.

[0068] Signals for monitoring the process may be provided by analog and / or digital input connections of the system controller 950 from various process tool sensors. Signals for controlling the process may be output at analog and digital output connections of the process tool 900. Non-limiting examples of process tool sensors that can be monitored include mass flow controllers, pressure sensors (such as manometers), thermocouples, and the like. Sensors may also be included and used to monitor and determine the build-up on one or more surfaces inside the chamber and / or the thickness of a material layer on a substrate within the chamber. Appropriately programmed feedback and control algorithms may be used with data from these sensors to maintain process conditions.

[0069] The system controller 950 may provide program instructions for implementing the deposition processes described above. The program instructions may control various process parameters, such as DC power levels, RF bias power levels, pressure, temperature, number of cycles of the substrate, amount of build-up on at least one surface inside the chamber, etc. The instructions may control parameters for operating the in-situ deposition of a film stack according to various embodiments described herein.

[0070] For example, the system controller may include control logic for performing the techniques described herein, including determining an amount of deposition material currently accumulated on at least one internal region within the deposition chamber, applying the amount of accumulated deposition material determined in (a), or a parameter derived therefrom, to a relationship between (i) the number of ALD cycles required to achieve the target deposition thickness and (ii) a variable representing the amount of accumulated deposition material to obtain a compensated number of ALD cycles to generate a target deposition thickness that accounts for the amount of deposition material currently accumulated on the internal region within the deposition chamber, and performing the compensated number of ALD cycles on one or more substrates in the batch of substrates. The system may also include control logic for determining that accumulation in the chamber has reached an accumulation limit, and, in response to the determination, for stopping processing of the batch of substrates and for cleaning the chamber interior.

[0071] The system controller will typically include one or more storage devices and one or more processors configured to execute instructions such that the device performs methods in accordance with the invention. A machine-readable non-transitory medium containing instructions for controlling process operations in accordance with the invention may be coupled to the system controller.

[0072] In some implementations, the controller is part of the system and may be part of the examples mentioned above. Such systems may include semiconductor processing equipment including 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.). These systems may be integrated with electronics for controlling pre-, during, and post-processing operations of semiconductor wafers or substrates. The electronics may be referred to as a "controller" and may control various components or subparts of one or more systems. The controller may be programmed to control any of the processes disclosed herein depending on the processing requirements and / or type of system. Such processes may include the number of cycles performed on the substrate, supply of process gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow settings, fluid supply settings, position and motion settings, loading and unloading of wafers into and out of the tool, and other transport tools and / or load locks connected or interfaced with the particular system.

[0073] In a broad sense, a controller may be defined as an electronic device having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, etc. Integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors or microcontrollers that execute the program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files) that define operational parameters for performing a particular process on or for a semiconductor wafer or for a system. In some implementations, the operational parameters may be part of a recipe defined by a process engineer to accomplish one or more processing steps during the manufacture of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies of a wafer.

[0074] In some implementations, the controller may be part of or coupled to a computer that is integral with, coupled to, or otherwise networked to the system, or a combination thereof. For example, the controller may be in the "cloud" and may be all or part of a fab host computer system. This allows for remote access of wafer processing. The computer may allow remote access to the system to monitor the current progress of a manufacturing operation, examine the history of past manufacturing operations, examine trends or performance criteria from multiple manufacturing operations, modify parameters of a current process, set processing steps following a current process, or initiate a new process. In some examples, a remote computer (e.g., a server) may provide a process recipe to the system over a network. Such a network may include a local network or the Internet. The remote computer may include a user interface that allows entry or programming of parameters and / or settings, which are then communicated from the remote computer to the system. In some examples, the controller receives instructions in the form of data. Such data identifies parameters for each of the processing steps that are performed during one or more operations. It should be understood that the parameters may be specific to the type of process being performed and the type of tool with which the controller is configured to interface or control. Thus, as discussed above, the controller may be distributed, such as by including one or more individual controllers that are networked together and cooperate toward a common purpose, such as the processes and controls described herein. One example of a distributed controller for such purposes would include one or more integrated circuits on the chamber that are located remotely (such as at the platform level or as part of a remote computer) and communicate with one or more integrated circuits that are coupled to control the process on the chamber.

[0075] In the foregoing detailed description, numerous specific details are set forth in order to provide a thorough understanding of the presented embodiments or implementations. The disclosed embodiments or implementations may be practiced without some or all of these specific details. In other instances, well-known process operations have not been described in detail so as not to unnecessarily obscure the disclosed embodiments or implementations. While the disclosed embodiments or implementations have been described in connection with specific embodiments or implementations, it will be understood that such description is not intended to limit the disclosed embodiments or implementations.

[0076] The foregoing detailed description has been directed to specific embodiments or implementations for the purpose of illustrating the disclosed aspects. However, the teachings herein may be applied and implemented in many different ways. In the foregoing detailed description, reference is made to the accompanying drawings. Although the disclosed embodiments or implementations have been described in sufficient detail to enable those skilled in the art to practice the embodiments or implementations, it should be understood that these examples are not limiting, and that other embodiments may be used, and changes may be made to the disclosed embodiments or implementations without departing from their spirit and scope. Furthermore, in this specification, the conjunction "or" is intended in an inclusive sense where appropriate, unless otherwise indicated, and for example, the expression "A, B, or C" is intended to include the possibilities of "A", "B", "C", "A and B", "B and C", "A and C", and "A, B, and C".

[0077] In this application, the terms "semiconductor wafer," "wafer," "substrate," "wafer substrate," and "partially fabricated integrated circuit" are used interchangeably. Those skilled in the art will appreciate that the term "partially fabricated integrated circuit" can refer to a silicon wafer during any of the many stages of integrated circuit manufacturing. Wafers or substrates used in the semiconductor device industry typically include diameters of 200 mm, or 300 mm, or 450 mm. The foregoing detailed description contemplates that embodiments or implementations are implemented on wafers or in connection with processes associated with the formation or manufacture of wafers. However, the claimed subject matter is not so limited. Workpieces may be of various shapes, sizes, and materials. In addition to semiconductor wafers, other workpieces in which the claimed subject matter may be utilized may include various articles such as printed circuit boards, or the manufacture of printed circuit boards.

[0078] Unless otherwise expressly required by the content of this disclosure, throughout the specification and claims, terms such as "comprises," "includes," and the like should be interpreted in an inclusive sense, i.e., "including, but not limited to," rather than an exclusive or exhaustive sense. Also, terms using a singular or plural number generally include the plural or singular number, respectively. When the term "or" is used in connection with a list of two or more items, the term includes all interpretations of the term, any item in the list, all items in the list, and any combination of items in the list. The term "embodiment" refers to an embodiment of the techniques and methods described herein, as well as a physical object that embodies the structure and / or incorporates the techniques and / or methods described herein.

Claims

1. 1. An apparatus for providing a signal to a station of a process chamber configured to perform a semiconductor manufacturing process, comprising: a plurality of signal generators configured to generate signals having first and second frequencies; a measurement circuit configured to measure a voltage standing wave ratio (VSWR); a matched reflection optimizer having a reactive component configured to be adjusted in response to an output signal from the measurement circuit; An apparatus comprising:

2. 2. The apparatus of claim 1, The apparatus, wherein the reactive component is configured for adjustment to modify the measured VSWR from a first value to a second value.

3. 2. The apparatus of claim 1, The apparatus, wherein the measurement circuit for measuring the VSWR corresponds to a phase sensitive voltage / current measurement circuit.

4. 2. The apparatus of claim 1, The apparatus, wherein the reactive component corresponds to a variable capacitor.

5. 2. The apparatus of claim 1, The apparatus further comprising a second measurement circuit for measuring a second VSWR at one or more input ports of the station.

6. 2. The apparatus of claim 1, The apparatus further comprises an isolation RF filter for providing between 25-40 dB of isolation between high frequency and low frequency portions of the apparatus.

7. 2. The apparatus of claim 1, The apparatus, wherein the matched reflection optimizer is configured to reduce the VSWR to a value below a threshold value.

8. 8. The apparatus of claim 7, The apparatus, wherein the threshold value of the VSWR corresponds to 1.15:

1.

9. 8. The apparatus of claim 7, The threshold value of the VSWR corresponds to 1.10:

1.

10. 1. A method for coupling a plurality of signals from a corresponding number of signal generators to a plurality of stations of a process chamber, comprising: Measuring a voltage standing wave ratio (VSWR) at an input port of the power divider; adjusting a value of a reactive component of a matched reflection optimizer in response to the measured VSWR, the adjustment of the reactive component resulting in a second VSWR that is lower than a first threshold value; A method comprising:

11. 11. The method of claim 10, The method of claim 1, wherein the reactive component comprises a variable capacitor.

12. 11. The method of claim 10, The method, wherein adjusting the VSWR includes reducing the VSWR to a value less than 1.15:

1.

13. 11. The method of claim 10, The method, wherein the measuring includes measuring the VSWR of a first signal having a frequency of about 400 kHz and a second signal having a frequency of about 27.12 MHz.

14. 14. The method of claim 13, The method further comprising attenuating the signal having the second frequency at the first frequency signal generator of the plurality of signal generators by an amount between 25 and 40 dB.

15. 11. The method of claim 10, measuring a VSWR at one or more input ports of the plurality of stations of the process chamber; adjusting a value of a reactive component of an RF power control circuit, the adjustment of the reactive component of the RF power control circuit resulting in a VSWR below a second threshold. The method further comprising:

16. 11. The method of claim 10, The method further includes adjusting a value of a reactive component of a π-matching circuit to lower the VSWR of a signal at a first frequency between 360 kHz and 440 kHz.

17. 11. The method of claim 10, The method further comprising adjusting the value of a reactive component of an L-type matching circuit to lower the VSWR at a second frequency between about 26.5 MHz and about 27.5 MHz.

18. 1. A manufacturing chamber for processing semiconductor wafers, comprising: one or more signal generators configured to generate corresponding RF signals to a process station of the fabrication chamber; a measurement circuit configured to measure a voltage standing wave ratio (VSWRs) of the RF signal; a control module for controlling a value of a reactive component disposed between the one or more signal generators and the station of the fabrication chamber, the control module being configured such that the value of the reactive component is adjusted to reduce each of the VSWRs of the RF signal to a value below a threshold VSWR; A manufacturing chamber comprising:

19. 20. The manufacturing chamber of claim 18, comprising: A manufacturing chamber, wherein the threshold VSWR corresponds to 1.15:

1.

20. 20. The manufacturing chamber of claim 18, comprising: A manufacturing chamber, wherein the threshold value of the VSWR corresponds to 1.10:1.

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