Impedance transformation in RF-assisted plasma generation

Abstract

An apparatus for providing a signal to a device may include one or more RF signal generators and a small electrical transmission line that couples the signal from the one or more RF signal generators to a manufacturing chamber. The apparatus may also include a reactance circuit to transform the impedance of the small electrical transmission line from a region of relatively high impedance sensitivity to a region of relatively low impedance sensitivity.

Description

[0001] Incorporated by Reference

[0002] The PCT application form is filed concurrently with this specification as a part of this application. Each application to which this application claims the benefit or priority as identified in the concurrently filed PCT application form is incorporated herein by reference in its entirety and for all purposes. Background Art

[0003] The descriptions of background and context contained herein are provided only for the purpose of presenting the context of the disclosure as a whole. Many of the present inventions are achievements of the inventors, and simply because such achievements are described in the background section or presented as context elsewhere in this article does not mean that such achievements are considered to be prior art.

[0004] The manufacture of semiconductor wafers used to form integrated circuits may include many different processing steps. In certain processing steps that may occur after various materials are deposited on the semiconductor wafer, materials may be etched away to allow additional materials such as metals to be deposited. Such deposition may involve the formation of conductive traces, transistor gates, vias, circuit elements, and the like. However, in at least some cases, semiconductor manufacturing processes, such as those involving plasma-based etching, plasma-enhanced atomic layer deposition, or other processes, uncontrollable process variations may result in lower yields, costs, semiconductor layout and mask redesign, and the like. In some cases, such uncontrollable process variations may result in response to changes in the energy coupled to the manufacturing chamber used to form the plasma. Therefore, techniques for increasing control over plasma-based wafer etching and / or plasma-enhanced atomic layer deposition or other manufacturing processes remain an active area of ​​research. Summary of the invention

[0005] In one aspect, an apparatus for providing a signal to a device is provided, wherein the apparatus comprises: one or more radio frequency (RF) signal generators; one or more small electrical transmission lines for coupling signals from the one or more RF signal generators to a fabrication chamber; and a reactance circuit for transforming the impedance of each of the small electrical transmission lines from a region having a first impedance sensitivity to a region having a second impedance sensitivity.

[0006] In some aspects, the reactance circuit includes at least a series reactance. In some aspects, the reactance circuit includes at least a shunt susceptance. In some aspects, the reactance circuit includes at least a series reactance and a shunt susceptance. In some aspects, the region of relatively high impedance sensitivity corresponds to a region in impedance space, and the real part of the impedance corresponds to a value greater than about 100 ohms. In some aspects, the region of relatively low impedance sensitivity corresponds to a region in impedance space, and wherein the real part of the impedance corresponds to a value less than about 100 ohms. In some aspects, the reactance circuit for transforming the impedance avoids the possibility of a resonant transmission line at any frequency less than the frequency of the signal from one or more of the RF signal generators. In some aspects, the electrically small transmission line corresponds to a transmission line that transforms impedance from the region of relatively high impedance sensitivity to the region of relatively low impedance sensitivity without traversing a transmission line resonance at a frequency less than the frequency of the signal generated by the RF signal generator in the medium of the transmission line. In some aspects, the resistive losses of the electrically small transmission line combined with the losses of the reactance circuit correspond to less than about 20%. In some aspects, the electrically small transmission line has a resistive loss corresponding to less than 10%.

[0007] In another aspect, an apparatus is provided, wherein the apparatus includes: a small electrical transmission line for coupling signals from one or more of the RF signal generators to a fabrication chamber; and a reactance circuit for transforming the impedance of the small electrical transmission line from an area of ​​relatively high impedance sensitivity to an area of ​​relatively low impedance sensitivity, the reactance circuit for moving an impedance control point in a direction opposite to the direction of movement through the length of the transmission line.

[0008] In some aspects, the electrically small transmission line corresponds to a transmission line that moves the impedance control point from the region of relatively high impedance sensitivity to the region of relatively low impedance sensitivity without traversing transmission line resonance at a frequency less than the frequency of the signal generated by the RF signal generator in the medium of the transmission line. In some aspects, the reactance circuit includes a series capacitive reactance. In some aspects, the reactance circuit includes at least a parallel inductance. In some aspects, the reactance circuit includes a series capacitive reactance and a parallel inductance. In some aspects, the resistive loss of the electrically small transmission line combined with the loss of the reactance circuit corresponds to less than about 20%. In some aspects, the resistive loss of the electrically small transmission line corresponds to less than 10%.

[0009] On the other hand, an integrated circuit manufacturing chamber is provided, wherein the integrated circuit manufacturing chamber includes: a plurality of integrated circuit manufacturing stations; one or more input ports for coupling a radio frequency (RF) signal to at least one of the plurality of integrated circuit manufacturing stations; a small electrical transmission line for coupling signals from one or more of the RF signal generators to the manufacturing chamber; and a reactance circuit for converting the impedance of the small electrical transmission line from a region of relatively high impedance sensitivity to a region of relatively low impedance sensitivity.

[0010] In some aspects, the region with relatively high impedance sensitivity corresponds to a region in impedance space, and wherein the real part of the impedance corresponds to a value greater than about 100 ohms. In some aspects, the region with relatively low impedance sensitivity corresponds to a region in impedance space, wherein the real part of the impedance corresponds to a value less than about 100 ohms. In some aspects, the region with the first impedance sensitivity corresponds to a region with low impedance sensitivity, and the region with the second impedance sensitivity corresponds to a region with high impedance sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A substrate processing apparatus is shown for depositing films on a semiconductor substrate using any number of processes.

[0012] Figure 2 is a block diagram illustrating various components of a system for performing a semiconductor manufacturing process according to an embodiment.

[0013] Figure 3 Power versus time for radio frequency (RF) power coupled to a station of a multi-station integrated circuit fabrication chamber is shown according to one embodiment.

[0014] Figure 4 FIG. 1 is a diagram showing coupling to a load (Z) through transmission lines of different lengths according to an embodiment. L ) and the corresponding impedance diagram in impedance space.

[0015] Figure 5A and 5B Impedance sensitivity at a control point of an RF matching unit in response to different lengths of transmission lines is depicted according to an embodiment.

[0016] Fig. 6A and 6B is a schematic diagram showing the use of an electrically small transmission line and a reactive element arranged to transform the impedance of a control point from a relatively high impedance sensitivity region of impedance space to a relatively low impedance sensitivity region of impedance space according to an embodiment.

[0017] Figure 7is a circuit diagram of a transmission line model according to an embodiment. DETAILED DESCRIPTION

[0018] In certain embodiments or implementations, impedance transformation in radio frequency (RF) assisted plasma generation can be used in various semiconductor manufacturing processes, such as plasma-based wafer manufacturing. Impedance transformation can bring the ability to more easily control the RF power delivered to a multi-station processing chamber in a manner that allows dynamic adjustment to the varying loads presented by one or more stations of the processing chamber. Such dynamic adjustment provides a real-time ability to match the load impedance presented by the plasma within the station to the source impedance of one or more RF power generators, even though such loads may experience significant increases and decreases during the course of the manufacturing process. Thus, the RF power delivered to the various stations can be increased, while the RF power reflected from the RF power generator can be reduced.

[0019] Certain embodiments or implementations may be used in a variety of wafer fabrication processes, such as various plasma enhanced atomic layer deposition (ALD) processes, various plasma enhanced chemical vapor deposition (CVD) processes, or may be used on-the-fly during a single deposition process. In certain implementations, the RF power matching network utilizes a simplified circuit topology to accommodate load variations at any signal frequency, such as medium frequencies (e.g., frequencies between 300 kHz and 3 MHz), high frequencies (e.g., frequencies between 3 MHz and 30 MHz), and very high frequencies (e.g., frequencies between 30 MHz and 300 MHz). However, in other implementations, the RF power matching network may operate at any signal frequency, such as at relatively low frequencies, such as frequencies between 50 kHz and 300 kHz, and at higher signal frequencies, such as frequencies above 300 MHz.

[0020] It should be noted that while specific embodiments described herein may show and / or describe small electrical transmission lines and reactive elements for use with 4 stations of a process chamber, in other embodiments, a smaller number of stations of a process chamber may be used, such as 1 station, 2 stations, or 3 stations. In other embodiments, small electrical transmission lines and reactive elements may be used with more stations of a process chamber, such as 5 stations, 6 stations, 7 stations, 8 stations, 10 stations, 12 stations, or any other number of stations of a process chamber.

[0021] The manufacture of semiconductor devices generally involves depositing one or more thin films on a planar or non-planar substrate in an integrated manufacturing process. In some aspects of the integrated process, it may be useful to deposit a thin film that conforms to the substrate morphology. One type of reaction that is useful in some cases involves chemical vapor deposition (CVD). In a typical CVD process, gaseous reactants are simultaneously introduced into the station of the reaction chamber and undergo a gas phase reaction. The reaction products are deposited on the substrate surface. The reaction can be driven by plasma, in which case the process may be referred to as a plasma enhanced chemical vapor deposition (PECVD) reaction. As used herein, unless otherwise indicated, the term CVD is intended to include PECVD. The CVD process has certain disadvantages that make it less suitable in some cases. For example, the mass transport limitations of the CVD gas phase reaction may result in a "bread loaf" deposition effect, which presents a thicker deposition at the top surface (e.g., the top surface of the gate stack) and a thinner deposition at the recessed surface (e.g., the bottom corner of the gate stack). In addition, because some dies have regions with different device densities, the mass transport effect across the substrate surface may result in thickness variations within the die and within the wafer. These thickness variations can lead to over-etching in some areas and under-etching in other areas, which can degrade device performance and die yield. Another issue associated with CVD processes is that they are generally unable to form conformal films in high aspect ratio features. This problem is likely to become more severe as device geometries continue to shrink.

[0022] In another example, some other deposition processes involve multiple film deposition cycles, each of which produces a "discrete" film thickness. For example, in atomic layer deposition (ALD), any technique that places thin film layers and is used to repeat the order of events can be considered to involve multiple deposition cycles. As device and feature sizes continue to shrink in the semiconductor industry, and as three-dimensional device structures become more prevalent in integrated circuit (IC) design, the ability to deposit thin conformal films (material films that have uniform thickness relative to the topography of the underlying structure, even if non-planar) becomes more important. ALD is a film forming technology that is well suited for conformal film deposition due to the fact that a single cycle of ALD deposits a single thin layer of material, the thickness of which is limited by the amount of one or more film precursor reactants, which can be adsorbed on the substrate surface (i.e., forming an adsorption-limited layer) prior to its own film-forming chemical reaction. Multiple "ALD cycles" can then be used to build up a film of the desired thickness, and because each layer is thin and conformal, the resulting film is substantially conformal to the shape of the underlying device structure. In certain embodiments, each ALD cycle includes the following steps:

[0023] The substrate surface is exposed to a first precursor.

[0024] Purge the reaction chamber where the substrate is located.

[0025] The reaction on the substrate surface is activated, typically using a plasma, and / or a second precursor.

[0026] Purge the reaction chamber where the substrate is located.

[0027] The duration of an ALD cycle may typically be less than 25 seconds, or less than 10 seconds, or less than 5 seconds.One (or more) plasma exposure steps of an ALD cycle may have a short duration, such as a duration of 1 second or less.

[0028] Figure 1 A substrate processing apparatus is shown for depositing films on a semiconductor substrate using any number of processes. Figure 1 The apparatus 100 uses a single processing station 102 of a process chamber having a single substrate holder 108 (e.g., a pedestal) in an interior volume that can be maintained under vacuum by a vacuum pump 118. A gas delivery system 101 and a showerhead 106 are also fluidly connected to the process chamber for delivering, for example, film precursors, carrier gases, and / or purge gases, and / or process gases, second reactants, etc. Figure 1 Also shown is equipment for generating a plasma in the processing chamber. Figure 1 The apparatus schematically depicted in FIG. 5 is suitable for performing, inter alia, plasma-enhanced CVD.

[0029] For simplicity, the processing apparatus 100 is depicted as an independent processing station (102) of a processing chamber, which is used to maintain a low pressure environment. However, it should be understood that multiple processing stations can be included in a common processing tool environment as described herein (e.g., within a common reaction chamber). For example, Figure 2 An implementation of a multi-station processing tool is depicted, which will be discussed in further detail below. In addition, it should be understood that in some implementations, one or more hardware parameters of the processing device 100 (including those discussed in detail herein) may be programmatically adjusted by one or more system controllers.

[0030] The station 102 of the processing chamber is in fluid communication with a gas delivery system 101 for delivering 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 regulating the process gases delivered to the showerhead 106. One or more mixing vessel inlet valves 120 may control the introduction of process gases into the mixing vessel 104.

[0031] Some reactants may be stored in liquid form prior to vaporization and subsequent delivery to the process station 102 of the process chamber. Figure 1The implementation scheme includes a vaporization point 103, which is used to vaporize the liquid reactant to be supplied to the mixing container 104. In some implementation schemes, the vaporization point 103 can be a heated liquid injection module. In some other implementation schemes, the vaporization point 103 can be a heated vaporizer. In other implementation schemes, the vaporization point 103 can be eliminated from the processing station. In some implementation schemes, a liquid flow controller (LFC) upstream of the vaporization point 103 can be provided to control the mass flow rate of the liquid used to vaporize and transport to the processing station 102.

[0032] The showerhead 106 distributes process gases and / or reactants (e.g., film precursors) toward the substrate 112 at the processing station, with the flow rate being controlled by one or more valves (e.g., valves 120, 120A, 105) upstream of the showerhead. Figure 1 In the illustrated implementation, the substrate 112 is positioned below the showerhead 106 and is shown as resting on a pedestal 108. The showerhead 106 can have any suitable shape and can have any suitable number and arrangement of ports to distribute process gases to the substrate 112. In some implementations having two or more stations, the gas delivery system 101 includes a valve or other flow control structure upstream of the showerhead that can independently control the flow of process gases and / or reactants to each station such that gases can flow to one station but not to another station. In addition, the gas delivery system 101 can be configured to independently control the process gases and / or reactants delivered to each station in a multi-station arrangement such that the gas composition provided to different stations is different; for example, the partial pressure of the gas components can vary between multiple stations at the same time.

[0033] The volume 107 is positioned below the showerhead 106. In some implementations, the pedestal 108 can be raised or lowered to expose the substrate 112 to the volume 107 and / or to change the volume of the volume 107. Optionally, the pedestal 108 can be lowered and / or raised during portions of the deposition process to adjust process pressures, reactant concentrations, etc. within the volume 107.

[0034] exist Figure 1 In the embodiment, the showerhead 106 and the base 108 are electrically coupled to the RF power supply 114 and the matching network 116 to power the plasma generator. In some implementations, the plasma energy can be controlled (e.g., via a system controller with appropriate machine-readable instructions and / or control logic) by controlling one or more of the processing station pressure, gas concentration, RF power source, etc. For example, the RF power supply 114 and the matching network 116 can be operated at any suitable power to form a plasma with a desired radical species composition. Similarly, the RF power supply 114 can provide RF power at any suitable frequency or frequency group and power.

[0035] In some implementations, plasma ignition and maintenance conditions are controlled using appropriate hardware and / or appropriate machine-readable instructions in a system controller, which can provide control instructions via a series of input / output control (IOC) instructions. In one example, instructions for setting a plasma for plasma ignition or maintenance are provided in the form of a plasma activation recipe for a process recipe. In some cases, the process recipe can be arranged sequentially so that all instructions for a process are executed simultaneously with the process. In some implementations, instructions for setting one or more plasma parameters can be included in a recipe before the plasma process. For example, a first recipe may include instructions for setting the flow rate of an inert gas (e.g., helium) and / or a reactive gas, instructions for setting a plasma generator to a power set point, and time delay instructions for a first recipe. A second subsequent recipe may include instructions for enabling a plasma generator and time delay instructions for a second recipe. A third recipe may include instructions for disabling a plasma generator and time delay instructions for a third recipe. It should be understood that within the scope of the present disclosure, these recipes may be further subdivided and / or repeated in any suitable manner.

[0036] In some deposition processes, the plasma excitation duration is about a few seconds or longer. In some implementations described herein, much shorter plasma excitations can be applied during a process cycle. These can be on the order of less than 50 milliseconds, with 25 milliseconds being a specific example.

[0037] For simplicity, in Figure 1 The processing apparatus 100 is depicted as a stand-alone station (102) of a processing chamber for maintaining a low pressure environment. However, it is understood that multiple processing stations may be included in a multi-station processing tool environment, such as Figure 2 , which depicts a schematic diagram of an embodiment of a multi-station processing tool.

[0038] The processing apparatus 200 employs an integrated circuit fabrication chamber 263 that includes a plurality of fabrication processing stations, each of which can be used to process a wafer held on a wafer holder (e.g., Figure 1 The processing operation is performed on the substrate in the susceptor 108. Figure 2 In the embodiment of FIG. 1 , an integrated circuit fabrication chamber 263 is shown having four processing stations 251, 252, 253, and 254, and four cables 266 that provide RF power to each of the four processing stations through input ports 267. Other similar multi-station processing apparatuses may have more or fewer processing stations depending on the implementation and, for example, the desired degree of parallel wafer processing, size / space constraints, cost constraints, etc. Figure 2Also shown is a substrate handling robot 275, which can be operated under the control of the system controller 290 and is configured to receive and store wafers from a wafer cassette (in Figure 2 The substrate is moved from the loading port 180 into the integrated circuit manufacturing chamber 263 and arrives at one of the processing stations 251, 252, 253 and 254.

[0039] Figure 2 An embodiment of a system controller 290 for controlling the processing conditions and hardware states of the processing device 200 is also depicted. The system controller 290 may include one or more memory devices, one or more mass storage devices, and one or more processors. The one or more processors may include a central processing unit, analog and / or digital input / output connections, a stepper motor controller board, and the like. In some embodiments, the system controller 290 controls all activities of the processing tool 200. The system controller 290 executes system control software stored in a mass storage device, which may be loaded into a memory device and executed on a hardware processor of the system controller. The software executed by the processor of the system controller 290 may include instructions for controlling timing, gas mixtures, chamber and / or station pressures, chamber and / or station temperatures, wafer temperatures, substrate pedestals, chuck and / or carrier positions, the number of cycles performed on one or more substrates, and other parameters of a specific process performed by the processing tool 200. These programmed processes may include various types of processes, including but not limited to: processes related to determining the amount of buildup on surfaces inside a chamber, processes involving multiple cycles related to the deposition of a film on a substrate, and processes related to a clean room. System control software executable by one or more processors of system controller 290 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 required to perform various tool processes.

[0040] In some embodiments, the software for execution by the processor of the system controller 290 may include input / output control (IOC) sequence instructions for controlling the various parameters described above. For example, deposition of a substrate and each stage of a deposition cycle may include one or more instructions executed by the system controller 290. Instructions for setting the processing conditions of an ALD / CFD deposition process stage may be included in a corresponding ALD / CFD deposition recipe stage. In some embodiments, the recipe stages may be arranged sequentially so that all instructions for a process stage are executed simultaneously with the process stage.

[0041] In some embodiments, other computer software and / or programs stored on a mass storage device of the system controller 290 and / or a memory device accessible to the system controller 290 may be employed. Examples of programs or program segments for this purpose include substrate positioning programs, process gas control programs, pressure control programs, heater control programs, and plasma control programs. The substrate positioning program may include program code for a process tool component that is used to load a substrate into ( Figure 2 The positioning program may include instructions for appropriately moving the substrate into and out of the reaction chamber as needed to deposit films on the substrate and to clean the chamber.

[0042] The process gas control program may include program code for controlling gas composition and flow rate and optionally for causing gas to flow into one or more processing stations to stabilize the pressure in the processing station before deposition. In some embodiments, the process gas control program includes instructions for introducing gas during film formation on a substrate in a reaction chamber. This may include introducing gas for one or more substrates in a batch of substrates for different numbers of cycles. The pressure control program may include program code for controlling the pressure in the processing station by adjusting, for example, a throttle valve in an exhaust system of the processing station, a gas flow rate flowing into the processing station, etc. The pressure control program may include instructions for maintaining the same pressure during deposition of different numbers of cycles on one or more substrates during batch processing.

[0043] The heater control program may include program code for controlling the flow of current to a ( Figure 1 Alternatively, the heater control program may control the delivery of a heat transfer gas (eg, helium) to the substrate.

[0044] In some embodiments, there may be a user interface associated with the system controller 290. The user interface may include a display screen, graphical software displays of apparatus and / or processing conditions, and user input devices such as pointing devices, keyboards, touch screens, microphones, and the like.

[0045] In some embodiments, the parameters adjusted by the system controller 290 may relate to processing conditions. Non-limiting examples include process gas composition and flow rate, temperature, pressure, plasma conditions, etc. These parameters may be provided to the user in the form of a recipe, which may be input using a user interface. The recipe for an entire batch of substrates may include a compensated cycle count for one or more substrates within the batch to account for thickness trends during processing of the batch.

[0046] Signals for monitoring the process can be provided by analog and / or digital input connections of the system controller 290 from various process tool sensors. Signals for controlling the process can be output by analog and / or digital input connections of the process tool 200. Non-limiting examples of process tool sensors that can be monitored include mass flow controllers, pressure sensors (e.g., manometers), thermocouples, etc. Sensors can also be included that are used to monitor and determine the thickness of the material layer on the accumulation on one or more surfaces inside the chamber and / or the substrate inside the chamber. Appropriately programmed feedback and control algorithms can be used together with the data from these sensors to maintain the process conditions.

[0047] The system controller 290 may provide program instructions for implementing the above-described deposition process. The program instructions may control various process parameters, such as DC power level, pressure, temperature, number of cycles for the substrate, amount of buildup on at least one surface within the chamber, etc. The instructions may control the parameters to operate the in-situ deposition of the film stack according to the various embodiments described herein.

[0048] For example, the system controller may include control logic for performing the techniques described herein, such as (a) determining an amount of accumulated deposition material currently on at least one interior region within the deposition chamber, applying the determined amount of deposition material or a parameter derived therefrom to a relationship between (i) the number of ALD cycles required to achieve a target deposition thickness and (ii) a variable representing the amount of accumulated deposition material to obtain a compensated number of ALD cycles for producing the target deposition thickness given the amount of deposition material currently accumulated on the interior 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 the accumulated amount in the chamber has reached an accumulation limit and stopping processing of the batch of substrates in response to the determination, and for causing a cleaning of the chamber interior.

[0049] In addition to Figure 2 In addition to the aforementioned determined functions and / or operations performed by the system controller 290, the controller can additionally control and / or manage the operation of the RF subsystem 295, which can generate RF power and deliver it to the integrated circuit fabrication chamber 263 via the RF input port 267. As further described herein, such operations can involve, for example, determining upper and lower thresholds of RF power to be delivered to the integrated circuit fabrication chamber 263; determining actual (e.g., real-time) levels of RF power delivered to the integrated circuit fabrication chamber 263, RF power activation / deactivation times, RF power on / off durations, operating frequencies, and the like.

[0050] In certain embodiments, integrated circuit fabrication chamber 263 may include input ports ( Figure 2 165). Thus, the integrated circuit fabrication chamber 263 can utilize eight RF input ports. In a particular embodiment, the processing stations 251-254 of the integrated circuit fabrication chamber 165 can each utilize a first and a second input port, wherein the first input port can transmit a signal having a first frequency and the second input port can transmit a signal having a second frequency. The use of dual frequencies can result in improved plasma characteristics, which can result in a deposition rate within certain limits and / or a deposition rate that is more easily controlled. Dual frequencies may result in other desired results, different from those described herein. In certain embodiments, frequencies between about 300 kHz and about 300 MHz can be utilized.

[0051] exist Figure 2 , the RF power from the RF signal source 276 can be divided among the four output channels, which can be coupled to corresponding ones of the input ports 267 of the integrated circuit fabrication chamber 263. In at least certain embodiments, it can be useful to divide the RF power from the RF signal source 276 into relatively equal parts (e.g., differing by about +1%). Thus, in an example, if the RF signal source 276 provides an output power of 1000W, then about 250W (+1%) is delivered to each input port 267 of the fabrication chamber 263.

[0052] Figure 3 FIG. 1 shows a power versus time plot of RF power coupled to a station of a multi-station integrated circuit fabrication chamber according to one embodiment. Figure 3 In FIG. 1 , the vertical axis represents the delivered power, which corresponds to the power delivered by the RF distribution unit, e.g. Figure 2 The total power delivered to the manufacturing chamber by the single input RF distribution unit 289 is shown in FIG. 2. As indicated by the fluctuation curve of the total input power, the power delivered to the single input RF distribution unit may vary significantly, for example, it may include variations of up to 100W, 150W, or 200W. Figure 3 Total power input and power input curves for the first and second processing stations (Sta1 and Sta2) are depicted, but in other embodiments, power can be coupled to more stations of a multi-station fabrication chamber, such as 3 stations, 4 stations, 5 stations, etc.

[0053] Fluctuations in power delivered to a single input RF distribution unit may occur in response to highly varying RF loads corresponding to individual stations of a multi-station integrated circuit fabrication chamber 263. For example, during transitions occurring within a station of the fabrication chamber 263, such as during a purge of gases used in an atomic layer deposition process, the RF load impedance presented by an individual station (e.g., one of stations 251, 252, 253, 254) may increase. In some cases, during the purge portion of an atomic layer deposition cycle, when precursor gases are purged or pumped from a process station, the load impedance presented by a particular station may increase significantly. This increase in load impedance may be used to reduce the power coupled to the process station. Conversely, during a portion of an atomic layer distribution cycle, when a volume of precursor gas is injected into the fabrication chamber, the input impedance presented by a particular station of the multi-station fabrication chamber may decrease significantly.

[0054] like Figure 3 As shown, the RF power coupled to station 1 (Sta1) is combined with the RF power coupled to station 2 (Sta2) to form the total input power. Figure 3 , it will be appreciated that if the total power input increases, the power coupled to each station of the multi-station fabrication chamber may be proportionally increased. Additionally, as the total power input decreases, the power coupled to each station of the multi-station fabrication chamber may be proportionally decreased. However, it will also be appreciated that when the total power input of the multi-station fabrication chamber decreases and the power coupled to a particular station (e.g., Sta 1) increases, the power coupled to one or more other stations (e.g., Sta 2) may be decreased to maintain a substantially constant total power input.

[0055] exist Figure 3 In an example that may be related to a multi-station fabrication chamber having two processing stations (Sta 1 and Sta 2), if the total power input remains stable, for example at a level of 100% of the nominal value, the power of a single station coupled to the multi-station fabrication chamber may be maintained at a value close to, for example, about 50% of the nominal value. However, as Figure 3 As shown, at times, the RF power coupled to a particular station (e.g., Sta1) may be increased, perhaps for a short period of time, in response to, for example, a decrease in load impedance caused by the conversion of a gaseous precursor into an ionized plasma material. In response to the increase in RF power at Sta 1, the RF power coupled to Sta2 may be decreased by an amount corresponding to that increase over a similar short period of time so that the sum equals the total power input. However, as Figure 3 As shown, the total power input to the fabrication chamber may occasionally decrease, which may occur due to a mismatch between the output impedance of the RF power generator and the input impedance of the fabrication chamber. In this case, when the total power input decreases and the power of a single station (e.g., Sta 1) increases, the power coupled to a different station (e.g., Sta 2) may approach Figure 3 The lower threshold is shown.

[0056] In certain embodiments, it may not be desirable for the power coupled to a single station to approach or reach a specific lower threshold. In some cases, in response to the power flow to a station of a multi-station manufacturing chamber dropping below the lower threshold, the station may represent a high impedance load. Therefore, the power coupled to other stations of the multi-station manufacturing chamber may increase, which may undesirably increase the plasma density in other manufacturing stations. In some cases, such an increase in power consumption at a station of a multi-station integrated circuit manufacturing chamber may lead to arcing or other abnormal plasma events. In some cases, power coupling below a threshold level may additionally lead to an imbalance in the deposition rate occurring within a multi-station manufacturing chamber. Therefore, for example, if the power coupled to a station is below the lower threshold of Sta 2, it may be necessary to extend the manufacturing process of Sta 2. Such an extension may include additional cycles, such as atomic layer deposition cycles, or may involve other additional processing and / or metrology to determine whether such a power reduction has a negative impact on the quality of the manufactured wafers.

[0057] Therefore, in order to reduce the incidence of power flow dropping below a lower threshold, it may be useful to ensure that the RF power coupled from the RF power generator (e.g., RF signal source 276) remains at a consistent and relatively high level. Figure 2 The output port of the single input RF distribution unit 289 may include a matching unit ( Figure 2 ), which can operate without user input to insert reactive components (e.g., series capacitors, series inductors, shunt capacitors, shunt inductors) into the input signal path from RF signal source 276. In some cases, single input RF distribution unit 289 can utilize one or more computer processors coupled to one or more memory circuits to allow execution of a set of computer-implemented instructions (e.g., algorithms) that can be used to dynamically insert reactive components into the signal path from RF signal source 276.

[0058] Figure 4 FIG. 1 is a diagram showing coupling to a load impedance (Z) through a transmission line of a first or second length according to an embodiment. L ) and the corresponding impedance diagram in a representative impedance space.

[0059] exist Figure 4 , schematic 401 shows that RF signal source 276 is indicated as providing input to single input RF distribution unit 289. As mentioned earlier herein, single input RF distribution unit 289 may utilize reactive components (e.g., series capacitors, series inductors, shunt capacitors, shunt inductors) that are connected in series. Figure 4The values ​​of the reactive elements Cser and Cshu may be computer controlled so as to be dynamically adjusted according to changes in the load presented by a single station of the multi-station integrated circuit fabrication chamber 263. The load impedance presented by a single station of the fabrication chamber 263 is Figure 4 Indicated as Z L Although in Figure 4 Not shown, but additional load impedances are presented by other stations (e.g., Sta 1, Sta 2, Sta 3, etc.) in fabrication chamber 263. In certain embodiments, a single station load Z L may correspond to a load with a relatively small real part and a relatively large imaginary part. Figure 4 In the specific example of Z L The measured impedance of the plane may be characterized as having a real impedance value between about 1-10 ohms and an imaginary impedance value between about 10-40 ohms.

[0060] In certain embodiments, a short electrical cable 266, such as a coaxial cable between about 35 inches and about 45 inches, can be used to couple a single input RF distribution unit 289 to an input port of a station in a multi-station integrated circuit fabrication chamber. Figure 4 In the example, Z L The load impedance presented in the representative impedance space 402 is from Z L The control point of the plane transformation to the output port of the single input RF distribution unit 289 corresponds to the Z L The plane is rotated through approximately a fraction of a wavelength in a transmission medium (e.g., a coaxial cable). In this case, the transmission medium may correspond to a 50 ohm coaxial cable. Thus, rotating the load through a fraction of a wavelength at the signal frequency (relative to the center point of representative impedance space 402) transforms the load to an impedance value corresponding to an impedance having a real part between approximately 25-50 ohms and a reactive component between approximately 100-200 ohms. Representative impedance space 402 shows point (1) being rotated through path (2), which corresponds to approximately a fraction of a wavelength, to reach point (3).

[0061] Understandably, Figure 4 The representative impedance space 402 includes a region with relatively low impedance sensitivity (corresponding to an interval of the representative impedance space where the real and imaginary parts of the impedance are less than about 100 ohms). The representative impedance space 402 may further include a region with relatively high impedance sensitivity (corresponding to an interval of the impedance space where the real and imaginary parts of the impedance are greater than about 100 ohms). Therefore, it can be understood that the load impedance Z L The plane rotates through a portion of the wavelength with an impedance Z LThe effect of switching from a region of low impedance sensitivity (e.g., corresponding to a region of relatively low real and imaginary impedance (e.g., a ratio of reactance to resistance < 2.5)) to a region of high impedance sensitivity (e.g., corresponding to a region of relatively high real and imaginary impedance (e.g., a ratio of reactance to resistance > 2.5)). However, as with respect to Figure 5A As discussed further, in some cases it may be difficult to determine the reactive component (e.g. Figure 4 The accurate values ​​of Cser and Cshu) are determined to obtain the capacitive or inductive reactance that provides a conjugate match or other type of match for providing a load impedance Z. L Provides maximum power flow and minimum reflected power.

[0062] Figure 5A and 5B The impedance sensitivity at the control point of the RF matching unit in response to different lengths of the transmission line is depicted according to an embodiment. Figure 5A As shown, it can be problematic to determine the real and imaginary components necessary to achieve a match (e.g., a conjugate match) that results in a low reflection coefficient if the load impedance is located in a region of high impedance sensitivity. Thus, transforming the impedance, for example, through an electrically short transmission line (at frequencies between 10 and 100 MHz) can result in an undesirably high standard deviation of the impedance introduced by the resistive and reactive circuit elements. Efforts to match such loads may therefore require multiple iterations as resistive and reactive elements are inserted into the matching network, tested to determine the effect of inserting such elements on the reflection coefficient (or voltage standing wave ratio), and then adjusted and remeasured in an effort to reduce the reflection coefficient below a threshold. This impedance transformation is particularly useful in applications where the impedance is not directly proportional to the impedance of the load. Figure 4 , where the load impedance ZL at point (1) is located in a region of low impedance sensitivity. Point (1) rotated through path (2) of the representative impedance space results in a load impedance ZL of L The conversion is to point (3) in the region of high impedance sensitivity.

[0063] However, again referring to Figure 4 , in the representative impedance space 403, using an RF cable (266) having a greater electrical length at a frequency between about 10 MHz and about 100 MHz can be used to reduce the load impedance Z L From the first region with low impedance sensitivity to the second region with low impedance sensitivity. Figure 4 As shown in the representative impedance space 403 of FIG. 4 , the rotation from point (1) through path (4) to point (5) corresponds to an impedance transformation from a point within the region of low impedance sensitivity to a second point within the region of low impedance sensitivity. The length of path (4) corresponds to the number of wavelengths represented by a 10-20 cable operating at frequencies between 10 MHz and 100 MHz. In one example, for example Figure 4 In the example (lower right), a 15 foot coaxial cable transmission line represents slightly more than one-half wavelength. It will also be appreciated that this rotation of path (4) avoids attempting to provide a conjugate match in a region of high impedance sensitivity.

[0064] Figure 5B The impedance space 403 ( Figure 4 ) indicates the uncertainty of the real and imaginary impedances at the point (5). Figure 5B As shown, the uncertainty around point (5) corresponds to a relatively low standard deviation in the impedance introduced by the reactive element to provide a conjugate match. Thus, matching such a load may require only a single measurement of the reflection coefficient, followed by the insertion of appropriate resistive and / or reactive circuit elements to drive the measured reflection coefficient to a value below the threshold.

[0065] However, it should be noted that, in addition to the regions of low impedance sensitivity and high impedance sensitivity, Figure 4 The representative impedance spaces 402 and 403 of may include resonant and anti-resonant intervals. For example, referring to the impedance space 403, the load impedance (Z L ) The transformation from point (1) to point (5) via an electrically long (e.g., between about 10 feet and about 20 feet) coaxial cable corresponds to cross-resonance and anti-resonance points in impedance space. For example, the load impedance Z shown on representative impedance space 403 is L The transformation from point (1) through path (4) is shown as intersection point (6), which may correspond to a point of theoretically infinite impedance. In this case, the voltage present on the transmission line (e.g., a coaxial cable) may increase to a relatively high value, while the current may decrease to a relatively low value. Such high voltage values ​​present in the transmission line in response to traversing the anti-resonance point (6) may cause dielectric breakdown of the coaxial cable and / or result in other undesirable consequences.

[0066] It should be noted that in certain embodiments, an impedance transformation may occur from a region having a first impedance sensitivity to a region having a second impedance sensitivity.

[0067] Path (4) shown on representative impedance space 403 also intersects or passes through point (7), which may represent a point where the theoretical impedance is 0 (zero). At this point, the voltage present on the transmission line (e.g., coaxial cable) may decrease to a very low or negligible value, while the current may increase to a very high value. Such high current values ​​may cause the coaxial cable to overheat, which may damage the coaxial cable and / or the RF signal source 276.

[0068] Furthermore, in addition to crossing resonant (e.g., high current / low voltage) points and anti-resonant (e.g., high voltage / low current) points, using longer cables (e.g., 15-foot cables) may result in other undesirable consequences, such as increased resistive losses. Furthermore, using longer cables may cause cable routing issues, where the excess cable length must be coiled, stored, or otherwise set aside so as not to interfere with other equipment associated with the manufacturing room. For example, the coiling of such excess cable length may create parasitic effects, where adjacent sections of the coiled cable affect each other, which may result in increased capacitance, which in turn affects the characteristic impedance (Z0) of the cable.

[0069] Thus, for the reasons discussed above, it may be desirable to use an electrically small transmission line (e.g., approximately 10 inches to 50 inches of coaxial cable) rather than an electrically longer transmission line (e.g., approximately 10 feet to 20 feet of coaxial cable). In this context, the term "electrically small" relates to a transmission line that transforms impedance from a region of relatively high impedance sensitivity to a region of relatively low impedance sensitivity without traversing transmission line resonances or transmission line anti-resonances at frequencies less than the frequency of a signal generated in the medium of the transmission line by an RF signal generator. Thus, as an example, a 40 inch transmission line transmitting signals at frequencies between 1 MHz and 50 MHz may be classified as electrically small because the load impedance Z is transformed ... L The transition from point (1) to point (3) in the representative impedance space does not traverse the anti-resonance point (6). On the other hand, a 15-foot transmission line carrying signals with frequencies between about 1 MHz and 50 MHz can be classified as electrically non-small because the load impedance Z L Transforming from point (1) to point (5) in the representative impedance space traverses the anti-resonance point (6).

[0070] Fig. 6A and 6B is a schematic diagram showing the use of an electrically small transmission line and a reactive component arranged to transform the impedance of a control point from a region of relatively high impedance sensitivity in impedance space to a region of relatively low impedance sensitivity in impedance space according to one embodiment.

[0071] like Fig. 6A As shown, an electrically long (e.g., 15 foot) cable is used to transform a load impedance (ZL) that represents the load presented by a processing station of a multi-station integrated circuit fabrication chamber 263. As previously described with reference to Figure 4 and 5A As discussed in 5B, the load impedance (Z L) can be transformed from a first point in a region of low impedance sensitivity to a second point in a region of low impedance sensitivity. Such control can be implemented at the single input RF distribution unit 289 through a computer controlled matching network (e.g., by executing an appropriate algorithm). However, as also previously described, the use of electrically long (e.g., 15-inch) cables or other transmission lines that allow for traversal of resonant or anti-resonant points of the representative impedance space may have undesirable consequences, such as increased resistive losses, parasitic capacitance variations, cable routing / storage issues, and the like.

[0072] Therefore, to avoid the above disadvantages, an electrical cable can be used together with an appropriate reactance circuit to transform the load impedance from the plane corresponding to the input port of the station of the multi-station manufacturing chamber to the desired control point. Certain embodiments can overcome the disadvantages of using an electrical cable, such as transforming the load impedance from an area of ​​low impedance sensitivity to an area of ​​high impedance sensitivity. Therefore, in Figure 6B In the load impedance (Z L ) is shown as transforming from point (1) to point (2A). As described earlier in this article, this transformation corresponds to a transformation of impedance from a region of low impedance sensitivity to a region of high impedance sensitivity. However, by inserting a lumped element shunt inductor (e.g., Figure 6B The impedance at the control point of a single RF distribution unit is moved in the representative impedance space by inserting the path created by L1. It can be appreciated, therefore, that such a transformation of the impedance of the control point may be desirable because it helps to avoid the necessity of matching in a high impedance sensitivity portion of the impedance space. By using a lumped element series reactance, such as C1, inserted in the circuit, Figure 6B As shown, an additional conversion of the load impedance from a high impedance sensitivity interval to a low impedance sensitivity interval can be achieved. It can be understood that the insertion of such reactance causes a shift in the control point, for example from Figure 6B From point (3A) to point (4) in the impedance space.

[0073] Therefore, in a specific embodiment, an RF distribution unit can be coupled to an input port using an electrical small transmission line to reach a station of a multi-station manufacturing room. Using such an electrical small transmission line can avoid various disadvantages, such as attempting to provide a conjugate match in an area of ​​high impedance sensitivity. Such an electrical small transmission line can be used in conjunction with the insertion of a circuit element that causes capacitive reactance or inductance. The use of such a circuit element helps to convert the impedance from an interval of high impedance sensitivity back to an interval of low impedance sensitivity. In addition, using such an electrical small transmission line, together with appropriate inductance / capacitance circuit elements that can be coupled as a series device or a parallel device, relatively low resistance losses can be provided, reducing capacitive coupling, such as capacitive coupling between adjacent segments of a long and perhaps coiled transmission line, and avoiding cable wiring problems. In a specific embodiment, by using an electrical small transmission line (e.g., a 10-inch to 50-inch coaxial cable), the resistance loss of the transmission line can be reduced to a minimum amount, such as less than 5%, less than 10%, or less than 15%. In addition, although the insertion of various circuit elements such as parallel inductors and series capacitors may cause resistance losses. Combined losses including transmission line losses as well as losses from various circuit elements may be kept below nominal levels, such as below about 20%.

[0074] Although Figure 6B The example of the embodiment utilizes the insertion of a shunt inductor to provide the inductive reactance and the series capacitor to provide the capacitive reactance, but in other embodiments, different circuit topologies may be used. Therefore, other embodiments may include various combinations of capacitive elements, inductive elements, resistive elements, transmission line lengths, etc., depending on the specific impedance transformation requirements.

[0075] Figure 7 is a circuit diagram of a transmission line model according to an embodiment.

[0076] exist Figure 7 In Figure 1, the series inductor (L) and the shunt capacitor (C) are shown. Figure 7 The lumped elements and Figure 6B In contrast to the lumped elements, Figure 6B A series capacitor (C1) and a shunt inductor (L1) are used. Therefore, Figure 6B The lumped circuit elements represent Figure 7 The relative (or opposite) model of the standard transmission line model.

[0077] In the foregoing detailed description, many specific details are set forth to provide a thorough understanding of the embodiments or implementations presented. The disclosed embodiments or implementations may be implemented without some or all of these specific details. In other cases, well-known process operations are not described in detail to avoid unnecessarily obscuring the disclosed embodiments or implementations. Although the disclosed embodiments or implementations are described in conjunction with specific embodiments or implementations, it should be understood that such description is not intended to limit the disclosed embodiments or implementations.

[0078] For the purpose of describing the disclosed aspects, the foregoing detailed description is directed to certain embodiments or implementations. However, the teachings herein may be applied and implemented in a variety of different ways. In the foregoing detailed description, reference is made to the accompanying drawings. Although the disclosed embodiments or implementations are described in sufficient detail to enable those skilled in the art to practice these embodiments or implementations, it should be understood that these examples are not restrictive; other embodiments or implementations may be used, and the disclosed embodiments or implementations may be changed without departing from the spirit and scope of the present invention. In addition, it should be understood that, unless otherwise stated, where appropriate, the conjunction "or" is intended to be inclusive in this article; for example, the term "A, B, or C" is intended to include the following possibilities: "A", "B", "C", "A and B", "B and C", "A and C" and "A, B and C".

[0079] In this application, the terms "semiconductor wafer", "wafer", "substrate", "wafer substrate", and "partially manufactured integrated circuit" are used interchangeably. It will be understood by those skilled in the art that the term "partially manufactured integrated circuit" can refer to a silicon wafer during any of the many stages of integrated circuit fabrication thereon. Wafers or substrates used in the semiconductor equipment industry typically include a diameter of 200 mm, or 300 mm, or 450 mm. The foregoing detailed description assumes that the embodiment or implementation is implemented on a wafer, or in conjunction with a process associated with forming or manufacturing a wafer. However, the claimed subject matter is not limited thereto. The workpiece can have a variety of shapes, sizes, and materials. In addition to semiconductor wafers, other workpieces that can utilize the claimed subject matter can include various items, such as printed circuit boards, or the manufacture of printed circuit boards, etc.

[0080] Unless the context of the present disclosure clearly requires otherwise, throughout the specification and claims, the words "include," "comprising," and the like are to be interpreted in an inclusive sense, rather than an exclusive or exhaustive sense; that is, in the sense of "including, but not limited to." Words using the singular or plural number generally also include the plural or singular number, respectively. When the word "or" is used to refer to a list of more than two items, the word encompasses all of the following interpretations of the word: any one of the items in the list, all of the items in the list, and any combination of the items in the list. The term "implementation" refers to implementations of the techniques and methods described herein, as well as physical objects that embody such structures and / or incorporate the techniques and / or methods described herein.

Claims

1. An apparatus for providing a signal to a device, comprising: one or more radio frequency (RF) signal generators; one or more small electrical transmission lines for coupling signals from the one or more RF signal generators to the fabrication chamber; as well as a reactance circuit for transforming the impedance of each of the one or more electrical small transmission lines from a region having a first impedance sensitivity to a region having a second impedance sensitivity, The one or more electrically small transmission lines corresponds to a transmission line that transforms impedance from a region of relatively high impedance sensitivity to a region of relatively low impedance sensitivity without traversing transmission line resonance at a frequency less than the frequency of the signal generated in the medium of the transmission line by an RF signal generator of the one or more RF signal generators.

2. The device according to claim 1, wherein: The reactance circuit includes at least a series reactance.

3. The device according to claim 1, wherein: The reactance circuit includes at least a shunt susceptance.

4. The device according to claim 1, wherein: The reactance circuit at least includes a series reactance and a shunt susceptance.

5. The device according to claim 1, wherein: The region having the first impedance sensitivity corresponds to a region of relatively high impedance sensitivity in impedance space, and wherein the real part of the impedance corresponds to a value greater than 100 Ohms.

6. The device according to claim 1, wherein: The region having the second impedance sensitivity corresponds to a region of relatively low impedance sensitivity in impedance space, and wherein the real part of the impedance corresponds to a value less than 100 Ohms.

7. The apparatus of claim 1, wherein the reactive circuit for transforming the impedance avoids the possibility of a resonant transmission line at any frequency less than a frequency of a signal from the one or more RF signal generators.

8. The apparatus of claim 1, wherein the resistive losses of the electrically small transmission line combined with the losses of the reactive circuit correspond to less than 20%.

9. The device according to claim 1, wherein: The electrically small transmission line resistance loss corresponds to less than 10%. 10 . The apparatus of claim 1 , wherein a region having the first impedance sensitivity corresponds to a region having low impedance sensitivity, and wherein a region having the second impedance sensitivity corresponds to a region having high impedance sensitivity.

11. An apparatus for an integrated circuit manufacturing chamber, comprising: an electrical small transmission line for coupling signals from one or more of the RF signal generators to the fabrication chamber; as well as a reactance circuit that transforms the impedance of the electrically small transmission line from a region of relatively high impedance sensitivity to a region of relatively low impedance sensitivity, the reactance circuit being operable to move the impedance control point in a direction opposite to the direction of movement through the length of the transmission line, wherein the electrically small transmission line corresponds to a transmission line that moves the impedance controlled point from the region of relatively high impedance sensitivity to the region of relatively low impedance sensitivity without traversing a transmission line resonance at a frequency less than a frequency of the signal generated by the RF signal generator in the medium of the transmission line.

12. The device according to claim 11, wherein The reactance circuit includes a series capacitive reactance.

13. The device according to claim 11, wherein: The reactance circuit includes at least a parallel inductance.

14. The device according to claim 11, wherein: The reactance circuit includes a series capacitive reactance and a parallel inductive reactance.

15. The device according to claim 11, wherein The resistive losses of the electrically small transmission line combined with the losses of the reactive circuit correspond to less than 20%.

16. The device according to claim 11, wherein The electrically small transmission line resistance loss corresponds to less than 10%.

17. An integrated circuit manufacturing chamber, comprising: multiple integrated circuit manufacturing sites; one or more input ports for coupling a radio frequency (RF) signal to at least one of the plurality of integrated circuit fabrication stations; an electrical small transmission line for coupling signals from one or more of the RF signal generators to the integrated circuit fabrication chamber; as well as a reactance circuit for converting the impedance of the electrically small transmission line from a region of relatively high impedance sensitivity to a region of relatively low impedance sensitivity, The one or more electrically small transmission lines corresponds to a transmission line that transforms impedance from a region of relatively high impedance sensitivity to a region of relatively low impedance sensitivity without traversing transmission line resonance at a frequency less than a frequency of the signal generated in the medium of the transmission line by an RF signal generator of the one or more RF signal generators.

18. The integrated circuit fabrication chamber of claim 17, wherein: The region of relatively high impedance sensitivity corresponds to a region in impedance space and wherein the real part of the impedance corresponds to a value greater than 100 ohms.

19. The integrated circuit fabrication chamber of claim 17, wherein: The region of relatively low impedance sensitivity corresponds to a region in impedance space and wherein the real part of the impedance corresponds to a value less than 100 ohms.

Images