Patent ID: 12198908

DETAILED DESCRIPTION

A pedestal in a semiconductor processing chamber may include components for delivering RF power to a plasma, as well as components for controlling the temperature of the substrate. An RF generator may send RF power through a lead to a wire mesh embedded in the pedestal supporting a substrate in the chamber. This RF power may be propagated through a gas above the substrate to form and control a plasma in the chamber for depositing material on the substrate. Additionally, a high-voltage heater control may transmit current through a lead to resistive heaters embedded in the pedestal to heat the substrate to a controlled temperature during the process. In order to maximize the amount of RF power that is transmitted to the plasma, the leads from the RF generator and the heater control may run through a filter box to minimize the RF power that leaks back through the heater leads rather than being transmitted to the plasma. While these filter circuits are fairly simple for one or two heater zones, they become more complex as the number of heater zones are increased. Specifically, the large inductors used to filter each lead quickly fill the physical volume of the filter box as the number of leads is increased.

In order to accommodate a growing number of heater zones in the pedestal, some embodiments decrease the volume used by the filter inductors in the filter box. Specifically, a resonant circuit comprising a resonant inductor and a resonant capacitor may allow the inductors on the leads from the heater zones to be much smaller. The resonant inductor may be magnetically coupled to the inductors on the leads from the heater zones. In effect, this allows multiple lead inductors to “share” the inductance on the resonant inductor, thereby allowing each individual lead inductor to be much smaller. Some embodiments may use a magnetic core, such as a ferrite rod or toroid that may be shared between the lead inductors and the resonant inductor. Multiple resonant circuits may be added to generate multiple filtering frequencies, thereby allowing any RF transients to be filtered from the heater leads while minimizing the space used in the filter box.

FIG.1Aillustrates a top plan view of a multi-chamber processing system100that may be configured to implement some embodiments described herein. The multi-chamber processing system100may be configured to perform one or more fabrication processes on individual substrates, such as silicon wafers, for forming semiconductor devices. The multi-chamber processing system100may include some or all of a transfer chamber166, a buffer chamber168, single wafer load locks170and172, processing chambers174,176,178,180,182, and184, preheating chambers183and185, and robots186and188. The single wafer load locks170and172may include heating elements173and may be attached to the buffer chamber168. The processing chambers174,176,178, and180may be attached to the transfer chamber166. The processing chambers182and184may be attached to the buffer chamber168. The operation of the multi-chamber processing system100may be controlled by a computer system190. The computer system190may include any device or combination of devices configured to implement the operations described herein. As such, the computer system190may be a controller or array of controllers and/or a general purpose computer configured with software stored on a non-transitory, computer-readable medium that, when executed, performs the operations described herein. One example of a suitable multi-chamber processing system100is the Endura® CL System manufactured by Applied Materials, Inc. of Santa Clara, California.

Each of the processing chambers174,176,178,180,182, and184may be configured to perform one or more process steps in the fabrication of a conductive structure in a semiconductor device, such as a contact structure for a field-effect transistor (FET). More specifically, the processing chambers174,176,178,180,182, and184may include one or more metal deposition chambers, surface cleaning and preparation chambers, thermal anneal and/or thermal hydrogenation chambers, and plasma hydrogenation/nitridization chambers.

FIG.1Billustrates a cross-sectional view of a wafer-processing chamber101, according to some embodiments. As shown, the processing chamber100may be an etch chamber suitable for etching a substrate154or for performing other wafer manufacturing operations. Examples of processing chambers that may be adapted to benefit from the embodiments describe herein may include the Producer® Etch Processing Chamber, and the Precision™ Processing Chamber, commercially available from Applied Materials, Inc., located in Santa Clara, California. It is contemplated that other processing chambers, including those from other manufacturers, may be adapted to benefit from these embodiments.

The processing chamber100may be used for various plasma processes. For example, the processing chamber100may be used to perform dry etching with one or more etching agents. The processing chamber may be used for ignition of plasma from a precursor CxFy(where x and y represent values for known compounds), O2, NF3, or combinations thereof. In another example, the processing chamber100may be used for a plasma-enhanced chemical vapor deposition (PECVD) process with one or more precursors.

The processing chamber100may include a chamber body102, a lid assembly106, and a pedestal104. The lid assembly106is positioned at an upper end of the chamber body102. The pedestal104may be disposed inside the chamber body102, and the lid assembly106may be coupled to the chamber body102and enclose the pedestal104in a processing volume120. The chamber body102may include a transfer port126, which may include a slit valve, formed in a sidewall of the chamber body102. The transfer port126may be selectively opened and closed to allow access to an interior of the processing volume120by a substrate handling robot (not shown) for substrate transfer.

An electrode108may be provided as a portion of the lid assembly106. The electrode108may also function as a gas distributor plate112having a plurality of openings118for admitting process gas into the processing volume120. The process gases may be supplied to the processing chamber100via a conduit114, and the process gases may enter a gas mixing region116prior to flowing through the openings118. The electrode108may be coupled to a source of electric power, such as an RF generator, DC power, pulsed DC power, pulsed RF, and/or the like. An isolator110may contact the electrode108and separate the electrode108electrically and thermally from the chamber body102. The isolator110may be constructed using a dielectric material such aluminum oxide, aluminum nitride, and/or other ceramics or metal oxides. A heater119may be coupled to the gas distributor plate112. The heater119may also be coupled to an AC power source.

The pedestal104may be coupled to a lift mechanism through a shaft144, which extends through a bottom surface of the chamber body102. The lift mechanism may be flexibly sealed to the chamber body102by a bellows that prevents vacuum leakage from around the shaft144. The lift mechanism may allow the pedestal104to be moved vertically within the chamber body102between a transfer position and a number of process positions to place the substrate154in proximity to the electrode108.

The pedestal104may be formed from a metallic or ceramic material. For example, a metal oxide, nitride, or oxide/nitride mixture may be used such as aluminum, aluminum oxide, aluminum nitride, an aluminum oxide/nitride mixture, and/or other similar materials. In typical implementations, one or more pedestal electrodes may be included in the pedestal104. For example, a first pedestal electrode157and a second pedestal electrode158may be provided in the pedestal104. The first pedestal electrode157and the second pedestal electrode158may be embedded within the pedestal104and/or coupled to a surface of the pedestal104. The first pedestal electrode157and the second pedestal electrode158may be a plate, a perforated plate, a mesh, a wire screen, or any other distributed conductive arrangement. AlthoughFIG.1illustrates only two pedestal electrodes, other embodiments may use more than two pedestal electrodes having different geometries and/or arrangements in the pedestal104as described in detail below.

A method known as bipolar chucking may be used with a first pedestal electrode157and a second pedestal electrode158. Bipolar chucking is a method of applying a DC voltage difference between the first pedestal electrode157and the second pedestal electrode158. This electrostatic difference serves to hold the substrate154to the pedestal104. This may be contrasted with monopolar chucking where only a single pedestal electrode is used, or where a DC voltage is only applied to a single pedestal electrode. Monopolar chucking only becomes effective when energy is applied to the plasma to complete the circuit. Bipolar chucking uses two separate electrical paths to each of the first pedestal electrode157and the second pedestal electrode158. In the example ofFIG.1A, a first DC voltage source may be applied to a first electrical pathway for the first pedestal electrode157. A second DC voltage source may be applied to a second electrical pathway for the second pedestal electrode158.

The one or more pedestal electrodes may be configured to deliver RF energy to a plasma in the processing volume120. For example, one or more RF sources may be provided outside of the chamber body102to provide RF energy to one or more pedestal electrodes in the pedestal104. The RF energy may be transferred through the one or more pedestal electrodes to a gas in the processing volume120that is deposited through the gas distributor plate112(also referred to as a “showerhead”) to generate a plasma. The plasma may be maintained above the substrate154to deposit a layer of material on the substrate154. In order to uniformly deposit material on the substrate154, the energy transferred to the plasma should be maintained uniformly across the surface area of the substrate154. In this example, the one or more RF sources may include a low-frequency generator153and/or a high-frequency generator159that may be configured to deliver multiple frequencies to the pedestal electrodes157,158. Common frequencies found in the pedestal104may include 350 kHz, 13.56 MHz, 27.12 MHz, 40.68 MHz, and/or the like.

In some embodiments, an RF filter box133may be included between the heater control155and the one or more heating elements139. The RF filter box133may be configured to perform a number of functions. For example, the RF filter box133may include a network of components, such as inductors151,152to prevent the RF power delivered by one RF source from reaching another. Some embodiments may also include an ESC P/S and FILTER195. In normal operation, the RF power is transmitted through the RF filter box133to the wire meshes of the pedestal electrodes157,158. From the pedestal electrodes157,158, the RF power may pass through the gas in the chamber to form the plasma. The RF power may then pass through the electrode108, traveling through the chamber body102and the shaft144into the return path of the RF filter box133. The RF power may then complete the circuit back to the one or more RF sources.

In some embodiments, the RF filter box133may be a distinct component in the processing chamber system. For example, the RF filter box133may include a housing with connectors that receive the leads from the heater control and/or the heater element(s) in the pedestal. The housing may enclose the filter circuit, which may include the inductors, capacitors, and resonant circuit described below.

In addition to the one or more pedestal electrodes157,158, some embodiments may also include one or more heating elements139in the pedestal104. The one or more heating elements139may include wires with a relatively low internal resistance that generate heat when an electrical current is run through the one or more heating elements139. For example, some heating elements may have a resistance of less than 10 ohms, such as 2 ohms. Power may be provided to the one or more heating elements139by a heater control155. The heater control155may provide voltage/current to the one or more heating elements139during a processing cycle to heat the pedestal104. This heat may be transferred to the substrate154to bring the substrate154into a predetermined temperature range during the process.

In addition to providing the input for the one or more RF sources, the RF filter box133may prevent RF signals from leaking into the heater control155and also present a high impedance to the RF for that path. For example, the RF power provided to the pedestal electrodes157,158may readily couple with the AC elements of the heating element(s)139through the dielectric. To minimize the RF power that is diverted away from the plasma, the RF filter box133may include a plurality of inductor/capacitor combinations for each input and/or output lead to/from the heater control155. For example, each individual RF filter in the RF filter box133may include a series capacitor (e.g., approximately 50 nF) and inductor (e.g., approximately 6 μH) to filter out RF signals on each of these lines. This combination of inductances and/or capacitances may be configured to generate a resonant peak with a high impedance at a particular high frequency while still allowing low frequencies to pass.

According to this arrangement, there may be a number of leads that run through the RF filter box. For example, RF leads may run up the shaft144to the pedestal electrodes157,158. Additionally, each heater zone in the pedestal104may be connected to a power lead and a return lead. Traditional pedestals typically used two heating zones, such as an inner zone and an outer zone, resulting in four leads (e.g., two power leads and two return leads) running through the RF filter box133. However, some embodiments may also be configured to use pedestals with many more heating zones, which complicates the RF filter box133as described below.

FIGS.2A-2Billustrate a pedestal104with a plurality of heating elements arranged into different heating zones, according to some embodiments. In this example, the plurality of heating elements may include seven separate and distinct heating elements. Note that this arrangement and the number of heating elements is provided only by way of example and is not meant to be limiting. The heater control described herein may be used with any number of heating elements. Furthermore, the heating control may be compatible with different arrangements of heating element types. As described below, the heater control may include leads that are compatible with high-power heating elements and low-power heating elements interchangeably.

In this example, the pedestal104may include a number of high-powered heating elements that are arranged in concentric circular areas radiating outward from a center of the pedestal104. A center or inner heating element210may have a disk or circular shape and be centered in the pedestal104. A middle heating element212may have a ring shape and may be positioned concentrically around the inner heating element210. An outer heating element214may also have a ring shape and may be positioned concentrically around the middle heating element212. These heating elements210,212,214may be configured to receive current from the heater control such that they can generate heat in the kilowatt range. These heating elements210,212,214may be used to set the primary temperature of the substrate. For example, to heat the substrate to temperatures of around 300° C. to around 800° C., the processing chamber may rely on these heating elements210,212,214with higher power ranges to provide the primary heat for heating the substrate to this temperature range.

This example may also include a number of low-power heating elements that are arranged around a periphery or perimeter of the pedestal104. The periphery of the pedestal104may be divided into quadrants, and a heating element may be located and shaped to cover each of the quadrants. For example, heating element220, heating element222, heating element224, and heating element226may be arranged around the periphery. These heating elements may be arranged in a ring that may be similar in diameter to the outer heating element214. In the cross-sectional view of the pedestal104, these low-power heating elements220,222,224,226may be placed on top of the high-power heating elements210,212,214, or vice versa. The low-power heating elements220,222,224,226may be used to fine-tune the temperature profile in specific areas of the pedestal104. Note that the specific geometry and arrangement of the low-power heating elements220,222,224,226are provided only by way of example and are not meant to be limiting. The low-power heating elements220,222,224,226may use power that is less than 100 W, such as between approximately 10 W and approximately 40 W. Other embodiments may include more or fewer low-power heating elements, which may be located in any of the middle, inner, and/or outer regions of the pedestal104.

In some embodiments, seven heater zones may require a power lead and a return lead for each zone, resulting in a large number of leads running through the RF filter box. Each of the heating elements may be modeled as a wire with an internal resistance that generates heat in the pedestal104. Therefore, basic implementations may use a power and return wire for each of the heating element. In the example above using seven distinct heating element, this would result in 14 different leads going to/from the pedestal104for the heating elements alone, along with at least two more leads for the DC chucking voltage and/or the RF power delivered to the pedestal electrodes.

FIG.3illustrates a circuit for combining return leads for different heating elements, according to some embodiments. In this example, the high-power heating elements in the inner, middle, and outer sections of the pedestal104may be modeled as resistances302in a circuit diagram. The resistances302may be connected to the heater control through a plurality of power leads304. In order to individually control each of the heating zones, each of the resistances302may be individually associated with one of the power leads304. For example, power lead304-1may be used to deliver current to resistance302-1for the inner heating element, power lead304-2may be used to deliver current to resistance302-2for the middle heating element, and power lead304-nmay be used to deliver current to resistance302-nfor the outer heating element.

While each of the resistances302may be associated with individual wires in the power leads304, each of these resistances302may also be associated with a shared return lead306. Sharing a return lead improves the processing chamber by minimizing the number of electrical leads that need to be routed through the pedestal104and filtered from other RF/DC signals in the pedestal104. However, when multiple heating zones share the same return lead306, this may increase the instantaneous current that is routed through the return lead306. As described below, this current may be filtered through an inductor and other circuit elements to remove RF signals that may be present in the pedestal104. An excessive amount of current may overheat the inductor and other circuit elements and damage or degrade the operation of the processing chamber, so the power provided through each power lead304may be duty cycle to prevent excessive current. An example of a heater control configured to control a seven-zone pedestal using nine leads is described in the commonly assigned U.S. patent application Ser. No. 17/167,904, filed on Feb. 4, 2021 entitled “Multi-zone Heater Control for Wafer Processing Equipment,” which is incorporated by reference herein in its entirety.

Turning back toFIGS.2A-2B, the plurality of leads may be combined into two groups: one group of three power wires and one shared return wire for the high-power heating elements, and one group of four power wires and one shared return wire for the low-power heating elements, which reduces the total number of wire leads down to nine wire leads for the heater. The RF filter box133may be provided to filter the RF signals that may be present in the pedestal104. As described above, the pedestal104may also include multiple wire meshes that provide RF power to a plasma in the processing chamber. To prevent the RF signal from traveling down the leads303and into the heater control300, the RF filter box133may be configured to remove RF signals in the frequency range of the pedestal104. The RF filter box133may also be configured to remove low-frequency signals and provide a low, stable resistance for DC voltages that are applied to the heating elements. For example, the RF filter box133may remove common frequencies found in the pedestal104, such as 13.56 MHz, 27 MHz, 40 MHz, and so forth.

A technical problem exists when trying to accommodate individual filters for a large number of heater leads, such as each of the nine leads used in a seven-zone pedestal. Specifically, the relatively large inductors used for each lead are difficult to accommodate in the physical space of the RF filter box133. In order to accommodate individual filters on each lead running to/from the heater control, some embodiments described herein solve this technical problem by introducing a resonant circuit that can be shared amongst the filter circuits on the heater control leads as they grow in number. This reduces the size of the individual inductors needed on each heater zone lead, and thus allows the RF filter box to accommodate a larger number of heater zones in the pedestal. As described below, this also allows the filter box to generate targeted resonant frequencies corresponding to frequencies to be filtered from the heater leads.

FIG.4Aillustrates an RF filter box for a pedestal having two heater zones, according to some embodiments. Although only two heater zones are illustrated inFIG.4Afor clarity, other embodiments may use the same principles to accommodate any number of heater zones and/or leads. Typically, heater zone controls406,412may be connected to leads for each heater zone408,410. The heater zone controls406,412may provide power with a relatively low frequency, such as 60 Hz, 50 Hz, or even DC signals. These frequencies may be very low compared to the relatively high frequencies provided to the plasma through the RF generators. For example, the frequency of the signal provided from the heater zone controls406,412may be at least one or two orders of magnitude less than the frequency of the RF power provided to the pedestal electrodes.

To allow the relatively low frequencies of the heater zone controls406,412to pass through to the heater zones408,410, inductors402and capacitors404for each lead may be arranged to generate filtering frequencies that are configured to filter the higher RF power frequencies for the pedestal electrodes. In this example, inductors402(also referred to as lead inductors, heater inductors, heater lead inductors, or a plurality of such inductors) may be connected in series on each lead between the heater zones408,410and the heater zone controls406,412. This may include inductors402on each power and return lead. In some embodiments, these inductors402may have a value of approximately 6.0 μH. Additionally, parallel capacitors404having a value of approximately 50 nF may be included in the filter box for each lead. These combinations of the inductors402and the capacitors404may be configured to generate a frequency response that passes the low frequency of the heater zone controls406,412while attenuating the much higher frequencies generated for the pedestal electrodes.FIG.4Billustrates a graph400of a frequency response of the circuit inFIG.4A, with the impedance looking into the filter box from the perspective of the heater zones. The impedance of the filter is illustrated as a function of frequency. The lower frequencies of the heater may be subject to a very low impedance, while the 6.0 μH inductor may generate a response configured to generate a high impedance (e.g., 500 ohms or more) at 13.56 MHz and above as illustrated.

FIG.5Aillustrates a resonant circuit that is magnetically coupled to the lead inductors for the heater controls, according to some embodiments. A resonant circuit may include a resonant inductor514and a resonant capacitor516. The resonant inductor514may be magnetically coupled to the lead inductors502connected to each of the leads between the heater zone controls406,412and the heater zones408,410. This allows the lead inductors502to be reduced in size and share the effect of the resonant inductor514, thus shrinking the overall size of the filtering circuits that need to fit inside the RF filter box.

Through the magnetic coupling, the resonant inductor514and the resonant circuit may be shared amongst the heater leads in the RF filter box. The resonant inductor514may be connected in series with the resonant capacitor516. The resonant circuit may be electrically isolated from the heater leads and/or other inductors502in the filter box such that current does not flow directly from the resonant circuit through the heater leads or inductors502.

FIG.5Billustrates a graph500of the impedance of the filter ofFIG.5Aas a function of frequency, as found by looking into the filter box from the perspective of the heater zones. The resonant circuit introduces a resonant peak530at approximately 13.56 MHz with a 0.5 μH inductor used for the resonant inductor514and a 250 pF capacitor used for the resonant capacitor516as examples. This allows the 6.0 μH size of the inductors502to be reduced down to approximately 2.0 μH. At 13.56 MHz, the filter may generate an impedance of greater than 1500 ohms. Not only does the resonant circuit allow the component sizes to be reduced for the inductors502, but it increases the impedance of the filter at the desired RF frequency. Thus, the resonant circuit allows the filters on each lead to fit within the physical volume of the filter box, and increases the effectiveness of the filter circuit in preventing RF power from the pedestal electrodes from leaking back down the heater leads.

Note that these frequencies and inductance/capacitance values are provided only by way of example for filtering a 13.56 MHz RF signal provided to the pedestal electrodes. As described below, additional resonant circuits may be added to the filter box to introduce additional resonant peaks at the other RF frequencies that may be present in the RF filter box. For example, given the frequency generated by the high-frequency RF generator, one having skill in the art may select component values for the resonant inductor514and the resonant capacitor516, as well as the lead inductors502to generate a corresponding frequency response to filter the given frequency. In some implementations, the resonant peak530may be selected to coincide with the frequency of the high-frequency generator. The frequency generated by the low-frequency generator need not always require a corresponding resonant peak, as the low-frequency RF power is less likely to be coupled through the dielectric of the pedestal to the heater zone.

FIG.6Aillustrates a filter box with a plurality of resonant circuits, according to some embodiments. In this implementation, a first resonant circuit may include a first resonant inductor624and a first resonant capacitor626. The first resonant inductor624may be magnetically coupled to a first plurality of lead inductors622. Similarly, a second resonant circuit may include a second resonant inductor614and a second resonant capacitor616. The second resonant inductor614may be magnetically coupled to a second plurality of lead inductors602. Multiple resonant circuits may be added to generate multiple resonant peaks at different frequencies. For example, multiple resonant peaks may be generated to filter the low-frequency generator, the high-frequency generator, and/or any other RF frequencies that may be present in the processing chamber. Including multiple resonant circuits may also allow the sizes of the lead inductors to be further reduced.

FIG.6Billustrates a graph600of the impedance of the filter ofFIG.6Aas a function of frequency, as found by looking into the filter box from the perspective of the heater zones. In this example, the first resonant circuit may include a 2.0 μH resonant inductor624and a 13 nF resonant capacitor626, which may generate an impedance of approximately 800 ohms at 2 MHz. Additionally, the second resonant circuit may include a 2.0 μH resonant inductor614and a 250 pF resonant capacitor616to generate an impedance of approximately 1500 ohms at 13.56 MHz. Note that the use of two resonant circuits is provided merely by way of example and is not meant to be limiting. Other embodiments may add any number of resonant circuits in order to generate additional resonant peaks corresponding to RF frequencies to be filtered from the filter box, such as the 350 kHz that may be used to modulate the ion energy in the chamber, or VHF frequencies such as 20 MHz, 40 MHz, 60 MHz, etc.

FIG.7illustrates one physical implementation of the resonant circuit, according to some embodiments. The filter circuit may be mounted to a printed circuit board (PCB)700having, for example, approximate dimensions of 130 mm×140 mm. In order to strengthen the magnetic coupling between the resonant inductor708and the lead inductors704,706, a magnetic core702may be used. In this example, a ferrite core having a toroid shape may be used as the magnetic core702. The resonant inductor708and the lead inductors706may be wrapped around the magnetic core702. The magnetic field lines from one inductor will tend to travel along the magnetic core702into neighboring inductors. The toroid shape of the magnetic core702may generate a closed loop for the magnetic field lines such that the coupling between the resonant inductor708and the other lead inductors706may be propagated around the magnetic core702. In this example, the magnetic core702may have an outer diameter of approximately 89 mm and an inner diameter of approximately 50 mm. The magnetic core702may stand approximately 51 mm high off of the PCB700. Other examples may use different dimensions for the magnetic core702without limitation.

As described above, any component values may be used to tailor the resonant peaks generated by the resonant circuits in the frequency response of the filters on the heater leads. As one example, the following component values may be used to implement the configuration illustrated inFIG.7. The magnetic core702may include a ferrite toroid, such as an example toroid having a 3.5 inch outer diameter, a 2.0 inch inner diameter, and a 2.0 inch total height. Inductors704-1,704-2,704-3,704-4, and704-5may include four turns of 12 gauge magnetic wire. Inductors706-1,706-2,706-3, and706-4may include four turns of 8 gauge magnetic wire. The resonant inductor708may include one turn of 8 gauge magnetic wire. The resonant capacitor712may include a 300 pF ceramic capacitor, and the lead capacitors710may include 47 nF film capacitors. These component values are provided only as one enabling embodiment and are not meant to be limiting.

FIG.8illustrates an alternative implementation using a magnetic core, according to some embodiments. In contrast to the implementation illustrated inFIG.7, some embodiments may use a magnetic core802having a shape of a ferrite rod. The ferrite rod may be substantially straight. This linear arrangement may serve as an alternative to the toroid shape discussed above. In contrast to the toroid shape, the linear shape of the magnetic core802may allow magnetic field lines to leak out of the magnetic core802. Thus, the strength of the magnetic coupling of the lead inductors806to a resonant inductor808may diminish towards the ends of the magnetic core802.

For example,FIG.8illustrates a circuit with two power leads and two return leads, resulting in a total of four lead inductors806in the filter box. The resonant circuit may include the resonant inductor808and a resonant capacitor812. The resonant inductor808may be more magnetically coupled to the lead inductors806-2,806-3that are directly adjacent to the resonant inductor808then to lead inductors806-1,806-4that are not adjacent to the resonant inductor808. Lead inductors806-1,806-4may use additional turns or windings to increase the magnetic coupling with the resonant inductor808.

FIG.9illustrates a simplified circuit diagram of the nine-lead implementation of the filter box, according to some embodiments. The resonant circuit may include a resonant inductor904and a resonant capacitor906connected in series to generate a resonant peak frequency. The resonant inductor904may be magnetically coupled to the lead inductors901on each of the leads routed to/from the heater zones in the pedestal. The parasitic capacitances902model the parasitic capacitance (e.g., approximately 2 pF) of a connector between the leads and the filter box, while the lead capacitances903provide a pathway to ground. By way of example, the resonant inductor904may have a value of approximately 0.5 μH and the lead inductors901may have values of approximately 2.0 μH. The resonant capacitance906may have a value of approximately 250 pF, and the lead capacitances may have values of approximately 50 nF.

FIG.10illustrates a flowchart1000of a method of filtering plasma RF signals from heater zone leads in a semiconductor processing chamber for processing semiconductor substrates, according to some embodiments. This method may be executed by the circuit components described in any of the preceding figures. For example, this method may be executed by a filter box that is connected to leads running to/from a pedestal. However, these functions may also be carried out by any electronic components capable of performing these functions, and thus this method need not be limited to being performed by the circuit elements described above, but instead may be performed by any circuits, processors, and/or electronic components capable of performing these functions.

The method may include receiving an RF frequency on a lead from a heater zone in a pedestal supporting a substrate in a processing chamber (1002). The RF frequency may be generated by an RF source and delivered to a wire mesh electrode in the pedestal to generate and/or control a plasma in the processing chamber. The RF frequency may include frequencies such as 13.56 MHz and other similar frequencies described herein. The RF signal may be leaked from a pedestal electrode into the heater element in the heater zone instead of being transmitted through the plasma as intended. The lead may include a power lead and/or a return lead running between a heater zone control and a heater zone in the pedestal. The heater zone control may generate a signal (e.g., an electrical current) having a frequency (e.g., 60 Hz) that is at least one order of magnitude lower than the RF frequency from the RF source received on the lead. This step may be executed as described in reference to any of the figures above.

The method may also include generating a resonant peak using an inductor on the lead from the heater zone that is magnetically coupled to a resonant inductor to produce the resonant peak (1004). As described above, the inductor may be connected in series on the lead in the filter box running between the heater zone and the heater zone control. This lead inductor may be magnetically coupled to the resonant inductor. The resonant inductor may be part of a resonant circuit comprising a resonant capacitor. The resonant circuit may generate the resonant peak that is incorporated into the frequency response of the overall filter circuit for the heater lead. The resonant circuit may include component values that generate a resonant peak that approximately matches the frequency of the leaked RF signal received on the lead. In some embodiments, the resonant inductor may be wound around a magnetic core, such as a ferrite core having a toroid or rod shaped. The magnetic core may be shared with the lead inductor and with other lead inductors in the filter box. This step may be executed as described in reference to any of the figures above.

The method may further include filtering the RF signal to prevent the RF signal from reaching a heater zone control corresponding to the heater zone (1006). The RF signal from the electrode may have a frequency that matches the resonant peak of the resonant circuit, and thus this RF signal may be attenuated before it reaches the heater zone control. This step may be executed as described in reference to any of the figures above.

It should be appreciated that the specific steps illustrated inFIG.10provide particular methods of filtering plasma RF signal from heater zone leads according to various embodiments. Other sequences of steps may also be performed according to alternative embodiments. For example, alternative embodiments may perform the steps outlined above in a different order. Moreover, the individual steps illustrated inFIG.10may include multiple sub-steps that may be performed in various sequences as appropriate to the individual step. Furthermore, additional steps may be added or removed depending on the particular applications. Many variations, modifications, and alternatives also fall within the scope of this disclosure.

In the foregoing description, for the purposes of explanation, numerous specific details were set forth in order to provide a thorough understanding of various embodiments. It will be apparent, however, that some embodiments may be practiced without some of these specific details. In other instances, well-known structures and devices are shown in block diagram form.

The foregoing description provides exemplary embodiments only, and is not intended to limit the scope, applicability, or configuration of the disclosure. Rather, the foregoing description of various embodiments will provide an enabling disclosure for implementing at least one embodiment. It should be understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of some embodiments as set forth in the appended claims.

Specific details are given in the foregoing description to provide a thorough understanding of the embodiments. However, it will be understood that the embodiments may be practiced without these specific details. For example, circuits, systems, networks, processes, and other components may have been shown as components in block diagram form in order not to obscure the embodiments in unnecessary detail. In other instances, well-known circuits, processes, algorithms, structures, and techniques may have been shown without unnecessary detail in order to avoid obscuring the embodiments.

Also, it is noted that individual embodiments may have been described as a process which is depicted as a flowchart, a flow diagram, a data flow diagram, a structure diagram, or a block diagram. Although a flowchart may have described the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be re-arranged. A process is terminated when its operations are completed, but could have additional steps not included in a figure. A process may correspond to a method, a function, a procedure, a subroutine, a subprogram, etc. When a process corresponds to a function, its termination can correspond to a return of the function to the calling function or the main function.

The term “computer-readable medium” includes, but is not limited to portable or fixed storage devices, optical storage devices, wireless channels and various other mediums capable of storing, containing, or carrying instruction(s) and/or data. A code segment or machine-executable instructions may represent a procedure, a function, a subprogram, a program, a routine, a subroutine, a module, a software package, a class, or any combination of instructions, data structures, or program statements. A code segment may be coupled to another code segment or a hardware circuit by passing and/or receiving information, data, arguments, parameters, or memory contents. Information, arguments, parameters, data, etc., may be passed, forwarded, or transmitted via any suitable means including memory sharing, message passing, token passing, network transmission, etc.

Furthermore, embodiments may be implemented by hardware, software, firmware, middleware, microcode, hardware description languages, or any combination thereof. When implemented in software, firmware, middleware or microcode, the program code or code segments to perform the necessary tasks may be stored in a machine readable medium. A processor(s) may perform the necessary tasks.

In the foregoing specification, features are described with reference to specific embodiments thereof, but it should be recognized that not all embodiments are limited thereto. Various features and aspects of some embodiments may be used individually or jointly. Further, embodiments can be utilized in any number of environments and applications beyond those described herein without departing from the broader spirit and scope of the specification. The specification and drawings are, accordingly, to be regarded as illustrative rather than restrictive.

Additionally, for the purposes of illustration, methods were described in a particular order. It should be appreciated that in alternate embodiments, the methods may be performed in a different order than that described. It should also be appreciated that the methods described above may be performed by hardware components or may be embodied in sequences of machine-executable instructions, which may be used to cause a machine, such as a general-purpose or special-purpose processor or logic circuits programmed with the instructions to perform the methods. These machine-executable instructions may be stored on one or more machine readable mediums, such as CD-ROMs or other type of optical disks, floppy diskettes, ROMs, RAMs, EPROMs, EEPROMs, magnetic or optical cards, flash memory, or other types of machine-readable mediums suitable for storing electronic instructions. Alternatively, the methods may be performed by a combination of hardware and software.