Patent ID: 12198896

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the example implementations. However, it will be apparent to one skilled in the art that the example implementations may be practiced without some of these specific details. In other instances, process operations and implementation details have not been described in detail, if already well known.

As used herein, the terms “about” and “approximately” mean that the specified parameter can be varied within a reasonable tolerance, e.g., ±10% in some implementations, ±15% in some implementations, or ±20% in some implementations.

Some implementations of the present disclosure provide a radio frequency (RF) antenna that is configured, when powered, to define a counter current inductor that generates localized magnetic fields for plasma generation. The RF antenna of the present disclosure enables generation of high density plasma (e.g. 1×10{circumflex over ( )}11 per cubic cm or greater in some implementations) with high distribution uniformity in a small volume process space, thereby enabling ALD/ALE in a high density plasma system. At present, ALD/ALE is not performed in high density plasma systems, due to the large process space and the excessive amount of time required to pump gases into, and purge gases from, the process space, which is prohibitive for purposes of throughput.

However, implementations of the present disclosure overcome these challenges by enabling localized fields and plasma generation in a small process space (e.g. approximately 3 inch (approximately 7.5 cm) vertical gap or less in some implementations, approximately 1 inch (approximately 2.5 cm) vertical gap or less in some implementations). With such a small process space, it is possible to achieve a low residence time of process gases in the chamber, enabling reduction in the ALD/ALE cycle time as the time required to move gases into and out of the chamber is reduced.

Broadly speaking, implementations of the present disclosure provide an RF antenna that includes an array of equally spaced parallel conductive lines that are oriented along a plane. When the RF antenna is powered, current flow in adjacent conductive lines occurs in opposite directions, thereby forming a counter current inductive array that inductively generates plasma in the process space/region of the chamber. The counter current inductive array is such that magnetic fields generated by each of the conductive lines are respectively localized to their originating conductive lines.

In some implementations, portions of the conductive lines are connected in series to enable the change in direction of current flow between adjacent conductive lines, as described further below.

FIG.1Ais a cross-sectional schematic diagram illustrating a plasma processing system100, in accordance with implementations of the disclosure. The plasma processing system100includes a process chamber102that is configured to receive a substrate for plasma processing. The componentry of the process chamber102encloses and defines a process region104, which is a space or volume in which plasma is generated for substrate processing. A pedestal106is configured to support the substrate (e.g. a wafer) so that the process region is defined over the substrate during processing.

An RF antenna110includes an array of conductive lines, which are shown in cross section in the illustrated implementation. The RF antenna110is powered by an RF source118through a match116, and also connected to ground. In some implementations, as further described below, the RF antenna110is composed of several individual segments, with each segment being powered (by individual or shared power source(s)) and connected to ground.

In some implementations, the RF antenna110is disposed between a top insulator112and a bottom insulator114. A side insulator108is also provided, which defines the internal sidewalls of the process region104.

Process gases are provided from a plurality of gas sources120, e.g. including a first reactant gas source for supplying the first reactant for the first half-reaction of the ALD process, a second reactant gas source for supplying the second reactant for the second half-reaction of the ALD process, and an inert gas source for supplying an inert gas for purging the process region104of the process chamber102. A gas switching module122is configured to manage the delivery of process gases from the gas sources120to the process chamber102. The gas switching module122may include a plurality of controllable valves and/or flow controllers to control the delivery of the process gases.

Process gases are delivered to a gas plenum124. From the gas plenum124, in some implementations, the process gases are routed into the process region104through a plurality of injectors126. The injectors126can define throughholes through the top and bottom insulators, and the injectors126can be horizontally distributed above the process region104so that process gases can be simultaneously introduced and evenly distributed throughout the process region104.

While a plurality of injectors are shown in the illustrated implementation, in other implementations, other hardware configurations can be employed to deliver process gases to the process region104. In some implementations, a center injector and/or side injectors are provided to deliver process gases into the process region104.

Gases (e.g. process gases, inert gas, reaction byproducts, etc.) are evacuated from the process region104through a baffle130by a vacuum pump132. It will be appreciated that the process region104can be maintained under vacuum by the vacuum pump132.

The process chamber102includes outer sidewalls134that are grounded.

Although not all specifically shown in detail, the process chamber102is typically coupled to facilities when installed in either a clean room or a fabrication facility. Facilities include plumbing that provide, among other things, processing gases, vacuum, temperature control, and environmental particle control. These facilities are coupled to the process chamber102, when installed in the target fabrication facility. Additionally, process chamber102may be coupled to a transfer chamber that will enable robotics to transfer substrates (e.g. semiconductor wafers) into and out of process chamber102using automation.

A programmable controller140is provided for controlling the operation of the process chamber102and its associated components, including, by way of example without limitation, the RF source118and match116, the gas switching module122, and the vacuum pump132. Broadly speaking, the controller108can be programmed to execute a chamber operation defined by a recipe. A given recipe may specify various parameters for the operation, such as the application of power to the RF antenna, the flow of gas into the chamber, and the application of vacuum. It should be appreciated that the timing, duration, magnitude, or any other adjustable parameter or controllable feature can be defined by a recipe and carried out by the controller to control the operation of the process chamber102and its associated components. Additionally, a series of recipes may be programmed into the controller140. In one implementation, the recipe is configured to process ALD operations.

FIG.1Bis a cross-sectional schematic diagram illustrating a plasma processing system100, in accordance with implementations of the disclosure. The implementation ofFIG.1Bdiffers from that ofFIG.1Aprimarily in that the RF antenna110is disposed over a dielectric window150(e.g. ceramic such as quartz), rather than being integrated into or sandwiched between insulators. In some implementations, the dielectric window150has a thickness in the range of about one-half to one inch (e.g. about 1 to 3 cm).

FIG.2is an overhead view of an RF antenna for plasma processing, in accordance with implementations of the disclosure. As shown, the RF antenna110has a serpentine shape, consisting of a series of parallel equally spaced conductive lines that are connected in series by looped ends. In other words, the RF antenna is defined by a continuous line that traces a path back and forth over the process region. In the illustrated implementation, the RF antenna110is powered at one end by an RF source118through a match116, and the other end of the RF antenna110is connected to ground.

Also shown in the overhead view is a substrate200. The RF antenna110is formed in the illustrated implementation to cover a circular area that encompasses the substrate200, and to inductively generate plasma in the process region of the chamber substantially over the entire exposed area of the substrate200.

In some implementations, the thickness (vertical dimension) of the RF antenna110is in the range of approximately 0.01 to 0.02 inches (approximately 0.02 to 0.05 cm). In some implementations, the RF antenna110is at a minimum distance from the sidewalls of the chamber, e.g. approximately 0.5 inch (1.3 cm) in some implementations. In some implementations, there is a minimum horizontal distance from the edge of the wafer to the turnaround of a given loop of the RF antenna110, e.g. approximately 0.5 inch (1.3 cm) in some implementations.

FIG.3is a conceptual cross-section view of a portion of a process chamber, in accordance with implementations of the disclosure. As shown, the RF antenna110is sandwiched between a top insulator112and a bottom insulator114. Side insulators108aand108bare joined to the periphery of the top and bottom insulators, so as to form a seal that enables the chamber to be operated under vacuum. The top and bottom insulators can be formed from a ceramic (e.g. quartz) or other insulating materials.

In order to achieve an inductively coupled plasma with high uniformity in a small vertical gap, it is important to have a localized magnetic field H (hence, E). Implementations of the present disclosure achieve this, generating a localized H by having the currents in any two adjacent lines running in the opposite direction. Parameters affecting the localization of the magnetic field and ultimately, the characteristics of the plasma generation, include the following: (1) line-line spacing (pitch), s, (2) line-plasma distance, d, (3) inductor line width, w.

In some implementations, the pitch s is in the range of about 0.5 to 2 inches (about 1 to 5 cm). In some implementations, s is approximately one inch (2.5 cm) for a vertical small gap on the order of approximately one inch (2.5 cm). In some implementations, s can be further reduced to approximately one-half inch (1.3 cm) in order to further improve the local electron density (Ne) uniformity of the small vertical gap (about one inch) geometry.

In order to maximize the plasma-skin induction current, d should be as small as physically and electrically feasible so as to maximize the induced fields. No limits are placed on the ratio s/d. In some implementations, a ratio of s/d>2 is generally considered for practical power-coupling and in fact, a maximum ratio s/d maximizes power-coupling as long as such geometry can be physically and electrically possible.

No limits are placed on the ratio of the vertical small-gap/s. In some implementations, small-gap/s>1 is generally considered for practical local Ne uniformity.

It is recognized that the field that penetrates into the plasma will become negligible if the spacing between lines (pitch) becomes much less than the thickness of the window. Also, if d is too small, then the conductive lines may be close to a Faraday shield, resulting in high stray capacitance.

Additionally, it is recognized that the conductive lines should have sufficient width and/or height to carry current, or they may be at risk of melting.

With continued reference toFIG.3, k is the wave vector indicating the direction of energy flow. The wave vector k is equal to the cross product of E and H, e.g. in units of Watts per meter squared.

As can be seen, the RF antenna110covers the process region in a way that other antennas cannot do. More specifically, the RF antenna110provides a very uniform density of flux lines over the entire area with a granularity in accordance with the spacing of the antenna lines. The line-line spacing can be optimized for the line-plasma distance, which may in turn be determined in part by the thickness of the bottom insulator or dielectric window, any distance from the dielectric window, skin depth, etc. The RF antenna110provides a uniform source of magnetic flux to drive currents everywhere across the process region area and hence provides uniform plasma production.

Existing TCP coils do not achieve uniformity in a small vertical gap because they are designed to generate and diffuse plasma throughout a larger volume and at relatively lower pressure. Such coils are designed to be a global antenna, inducing currents throughout the plasma chamber in a large circular pattern, with attendant stochastic effects. Thus, such existing chambers do not have the property of low residence time. With a conventional TCP coil, it is not possible to achieve high uniformity very close to the window. And thus if the vertical gap of the chamber were simply reduced in an attempt to reduce the residence time, this would bring the non-uniformity close to the wafer surface.

However, with the RF antenna provided in accordance with implementations of the present disclosure, there are not the global current circulation and stochastic effects seen in existing coils. But rather, effects are localized, enabling high uniformity of plasma in a narrow vertical gap very close to the window.

FIGS.4A,4B,4C,4D,4E,4F,4G, and4Hillustrate various examples of RF antenna110having various dimensions and coverage configurations, in accordance with implementations of the disclosure.

The implementations ofFIGS.4A-Dillustrate the RF antenna110having a substantially circular coverage area, so as to provide coverage over the entire horizontal area of the substrate. In the implementation ofFIG.4A, the RF antenna110has a width of approximately 0.25 inch and a pitch of approximately 1 inch per line. In the implementation ofFIG.4B, the RF antenna110has a width of approximately 0.38 inch and a pitch of approximately 1 inch per line. In the implementation ofFIG.4C, the RF antenna110has a width of approximately 0.50 inch and a pitch of approximately 1 inch per line. In the implementation ofFIG.4D, the RF antenna110has a width of approximately 0.5 inch and a pitch of approximately 1.5 inches per line.

The implementations ofFIGS.4E-Hillustrate the RF antenna110having a substantially rectangular coverage area. In the implementation ofFIG.4E, the RF antenna110has a width of approximately 0.25 inch and a pitch of approximately 1 inch per line. In the implementation ofFIG.4F, the RF antenna110has a width of approximately 0.38 inch and a pitch of approximately 1 inch per line. In the implementation ofFIG.4G, the RF antenna110has a width of approximately 0.50 inch and a pitch of approximately 1 inch per line. In the implementation ofFIG.4I, the RF antenna110has a width of approximately 0.25 inch and a pitch of approximately 1.5 inches per line. It will be appreciated that the parameters of the RF antenna110, such as the width, pitch, and turns, can be optimized to provide for the desired density and uniformity of plasma when in operation. Currents induced in the plasma mirror the currents going back and forth along the RF antenna110.

FIG.5illustrates an overhead view of an RF antenna110defined as a single continuous length of a conductive material, in accordance with implementations of the disclosure. Generally speaking, the RF antenna110is defined by an array of parallel equally spaced conductive lines, such as the conductive lines504a,504b,504c, and504das indicated in the illustrated implementation. The conductive lines are substantially straight portions of the RF antenna110, and when the RF antenna110is powered, current in adjacent ones of the conductive lines runs in opposite directions, forming a local countercurrent. For example, when powered, the current in conductive line504cwill run in the opposite direction as the current in adjacent conductive line504d. To achieve this countercurrent setup, the conductive lines are connected in series to each other. For example, the conductive lines504a,504b,504c, and504dare connected in series. Conductive line504ais connected to conductive line504bby a connector506a; conductive line504bis connected to conductive line504cby a connector506b; and, conductive line504cis connected to conductive line504dby a connector506c.

In the illustrated implementation, the connectors are shown as curved lines or semicircular shaped. However, in other implementations the connectors can have other shapes. In some implementations, each connector is defined by a single straight line connecting segment. In some implementations, each connector is defined by two or more straight line connecting segments. In some implementations, the RF antenna110may have different shaped connectors at different portions of the RF antenna110.

The RF antenna110has a first end500that is powered, and a second end502that is connected to ground. As shown, the RF antenna110has a serpentine shape that defines a current path configured to flow back and forth along and parallel to a first axis, while traversing a second axis perpendicular to the first axis from one side of the chamber to the opposite side of the chamber. The RF antenna110thus defines a countercurrent inductor that produces localized plasma induction.

In the illustrated implementation, the RF antenna110has a single continuous length. In such implementations with and single continuous length, if the length is too long for the frequency at which the system operates, there may be transmission line effects as the whole length may not be sufficiently in phase, and the inductance may be too high. For example, at a frequency of 13.56 MHz, and an RF antenna110length of about 3-10 feet, the entire length can be considered to be in phase. However, if the length is significantly longer, then there may be transmission line effects. One possibility to address such issues is to lower the frequency. However, another way is to break down the conductive length into different segments, which lowers the inductance.

With continued reference toFIG.5, in some implementations, each of the conductive lines has a segment length of approximately 17 inches (approximately 43 cm); in some implementations, approximately 15-20 inches (approximately 38 to 51 cm). In some implementations, the line-to-line spacing is approximately 1 inch (approximately 2.5 cm); in some implementations, approximately 0.5 to 1.5 inches (approximately 1.3 to 3.8 cm). In some implementations, the line width is approximately 0.25 inch (approximately 0.6 cm); in some implementations, approximately 0.1 to 0.5 inch (approximately 0.2 to 1.3 cm).

FIG.6illustrates an overhead view of RF antenna110consisting of two distinct segments, in accordance with implementations of the disclosure. As shown, the RF antenna110has a segment600and a segment606. The RF antenna110still consists of an array of conductive lines that are parallel and equally spaced. However, the conductive lines are divided into two segments, with the segment600including half of the conductive lines connected in series, and the segment606including the other half of the conductive lines connected in series. The segment600is powered at a first end602and grounded at a second end604. The segment606is powered at a first end608and grounded at a second end610.

In some implementations, power is split from a single power source to each of the first ends602and608of the segments600and606respectively. In other implementations, power is provided from separate power sources to each of the first ends respectively. In either case, when the RF antenna110is powered, each pair of adjacent conductive lines of the RF antenna110exhibits current flow in opposite directions, so that RF antenna110functions as a countercurrent inductor.

In some implementations, the RF antenna110in accordance withFIG.6has dimensions similar to those described with reference to the implementation ofFIG.5.

FIG.7illustrates an overhead view of an RF antenna110having multiple hairpin-shaped segments, in accordance with implementations of the disclosure. In the illustrated implementation, the RF antenna110consists of segments700,702,704,706,708,710,712,714, and716. Each segment has a hairpin shape consisting of two adjacent and parallel conductive lines that are connected by a connector on one side. For example, the segment700includes conductive lines718and720, connected on one side by a connector722. An adjacent segment702includes conductive lines728and730, connected on the opposite side by a connector732.

The segment700is powered at a first end724, and has a second end726connected to ground. The segment702is powered at a first end734, and has a second end736connected to ground. The remaining segments are similarly configured to be powered and grounded. In some implementations, the segments may each receive RF power that is uniformly or adjustably split from a power source. It will be appreciated that the segments are arranged as shown, so that when the RF antenna110is powered, adjacent lines exhibit current flow in opposite directions, thereby enabling the RF antenna110to function as a countercurrent inductor.

In some implementations, the RF antenna110is powered at a frequency of 13.56 MHz and a total power W. In some implementations, the power to each segment is equal to W divided by the number of segments of the RF antenna110.

FIG.8illustrates an overhead view of an RF antenna110having multiple segments, in accordance with implementations of the disclosure. In the illustrated implementation, each segment includes three conductive lines connected in series. The RF antenna110as shown includes segments800,802,804,806,808, and810. By way of example, the segment800includes conductive lines812,814, and816connected in series by connectors818and820as shown. Similarly, the segment802includes conductive lines826,828, and830connected in series by connectors832and834. The remaining segments are similarly configured. Each segment thus exhibits a double reverse hairpin shape, with two 180 degree turns for each segment.

The segment800receives power at a first end822, and a second end824is connected to ground Likewise, the segment802receives power at a first end836, and a second end838is connected to ground. The other segments are similarly configured. In some implementations, RF power can be uniformly or adjustably split from a power source to the segments of the RF antenna110. It will be appreciated that the segments are arranged as shown, so that when the RF antenna110is powered, adjacent lines exhibit current flow in opposite directions, thereby enabling the RF antenna110to function as a countercurrent inductor.

In some implementations, the RF antenna110is powered at a frequency of 13.56 MHz and a total power W. In some implementations, the power to each segment is equal to W divided by the number of segments of the RF antenna110.

FIG.9Aillustrates an overhead view of an RF antenna110having multiple double reverse hairpin segments, in accordance with implementations of the disclosure. In the illustrated implementation, the RF antenna110includes segments900,916,940, and956. Each segment is powered by a separate power supply, thus enabling the RF power provided to each segment to be individually tuned. This can be leveraged to improve deposition uniformity, for example, or even to intentionally produce a differential deposition profile. Segment900is powered by power supply912and connected to ground through a termination module914; segment916is powered by power supply928and connected to ground through a termination module930; segment940is powered by power supply952and connected to ground through a termination module954; segment956is powered by power supply968and connected to ground through a termination module970.

Segment900includes conductive lines902,904, and906, connected in series by connectors908and910; segment916includes conductive lines918,920, and922, connected in series by connectors924and926; segment940includes conductive lines942,944, and946, connected in series by connectors948and950; and segment956includes conductive lines958,960, and962, connected in series by connectors964and966.

As conceptually shown by the arrows on the conductive lines, when the RF antenna110is powered, current flow in adjacent conductive lines occurs in opposite directions, thus forming a countercurrent inductor.

In some implementations, the RF antenna110is powered at a frequency of 13.56 MHz and a total power W. In some implementations, the power to each segment is equal to W divided by the number of segments of the RF antenna110. For example, in the case of four segments as shown, the power to each segment is equal to W/4.

FIG.9Bis a cross-section view of the implementation ofFIG.9A, in accordance with implementations of the disclosure. InFIG.9B, the components of the RF antenna110are shown disposed over a dielectric window980. Shown below the dielectric window980is a ground electrode982.

FIG.10Aillustrates a conceptual cross-section of an RF antenna110in accordance with implementations of the disclosure. Shown is a cross-section view along a length of one of the conductive lines1000of the RF antenna110. Conductive lines1000may also be referred to as inductor lines. The RF antenna110is formed between a top insulator112and a bottom insulator114. Also disposed within the bottom insulator and below the RF antenna110is a Faraday shield1002. The Faraday shield1002includes lines that are oriented perpendicular to the orientation of the conductive lines of the RF antenna110. Thus in the illustrated implementation, the Faraday shield1002appears as a series of short segments below the conductive line1000, as the view is cross-sectional across the Faraday shield's lines.

FIG.10Billustrates a conceptual cross-section in accordance with the implementation ofFIG.10A. The view shown atFIG.10Bis perpendicular to that ofFIG.10A. Thus, the illustrated cross-section ofFIG.10Bis perpendicular to the orientation of the conductive lines1000of the RF antenna110, and several individual conductive lines1000are visible. In some implementations, between the individual conductive lines1000, there is epoxy1004, which bonds the top insulator112and the bottom insulator114.

The electrostatic Faraday shield1002absorbs the electric field from the conductive lines, so that electric field will not pass through into plasma. The arrows shown atFIG.10Aillustrate electric field lines terminating on the Faraday shield1002. Thus, only the magnetic fields pass through the ceramic into the plasma skin to be absorbed.

In some implementations, the Faraday shield is designed such that the capacitance between the inductor lines and the Faraday shield is a controllable quantity. In some implementations, the Faraday shield1002is at ground, so if the stray capacitance is too high compared to the series resonance capacitance, then the ICP match won't tune.

Further illustrated atFIG.10Bis the wave vector K, indicated by arrows beneath the inductor lines. Directly below the inductor line the direction of energy flow is straight down. But away from the inductor line, the direction of energy flow changes because the magnetic field is curved.

The Faraday shield can function to block capacitive coupling from the RF antenna110to plasma. In some implementations, the Faraday shield is grounded; whereas in some implementations, the Faraday shield is floating.

In some implementations, the Faraday shield is powered, to sputter the window to keep it clean. Additionally, if the Faraday shield is powered, then this could be used to assist in ignition and plasma stability.

FIG.11Aillustrates a perspective view of an RF antenna110having raised end loops, in accordance with implementations of the disclosure. In the RF antenna110the looped ends may cause some transformer effect. Therefore, in some implementations, this effect can be reduced by bending the end loops up at an angle (e.g. approximately 90 degree angle). This will also reduce the end loops' current induction into the chamber.

In the illustrated implementation, the RF antenna110includes conductive lines that are connected in series by raised end loop connectors. For example, the conductive lines1100,1104,1108,1112, and1116are connected in series by connectors1102,1106,1110, and1114as shown. The connectors are curved segments (e.g. semicircular) and each is oriented along a plane that is substantially perpendicular to the plane along which the conductive lines are oriented. The connectors define a current path, from one conductive line to another, that travels upward out of the plane of the conductive lines, and then travels downward back into the plane of the conductive lines.

In the illustrated implementation, the RF antenna110is configured to cover a substantially circular region of the chamber, so as to cover and extend beyond the area of the substrate surface that is beneath it. Accordingly, when the connectors are configured to have substantially the same shape as in the illustrated implementation, then the sizes of the connectors may vary as the distance between the ends of adjacent conductive lines may vary depending upon their positioning within the overall array of conductive lines. As shown, adjacent conductive lines positioned towards the ends of the RF antenna110have larger connectors (e.g. connector1102) than adjacent conductive lines positioned towards the center of the RF antenna110(e.g. connector1114).

FIG.11Billustrates a cutaway view of a process chamber102including the RF antenna110in accordance with the implementation ofFIG.11A. In some implementations, the RF antenna110is positioned above a dielectric window that may consist of top and bottom insulators112and114. In some implementations, the RF antenna110is positioned between the top and bottom insulators112and114.

Also shown are contact structures1120and1122which define electrical contacts for the RF antenna110. For example, the contact structure1120may receive RF power from a power source, while the contact structure1122is connected to ground.

FIG.11Cillustrates a perspective view of the process chamber102in accordance with the implementation ofFIG.11B. The region of the process chamber102above the RF antenna110can be provided with airflow to cool this region and more specifically cool the RF antenna110and prevent it possibly melting.

FIG.11Dillustrates an overhead view of the process chamber102in accordance with the implementation ofFIG.11B. An advantage of the upturned end loop connectors of the RF antenna110is that the straight conductive lines can be extended close to the chamber edge, so that the length/reach and coverage area of each conductive line is maximized. In some implementations, a minimum distance from the chamber edge is defined for the RF antenna110(e.g. approximately 0.5 inch, or 1.3 cm), and the conductive lines may therefore extend up to or close to the minimum distance from the chamber edge that is defined. In this manner, the conductive lines extend beyond the edge of the substrate200to the maximum extent possible, thereby promoting uniformity of plasma generation over the substrate edge regions.

FIG.12Aillustrates a cutaway view of a process chamber102, in accordance with implementations of the disclosure. In the illustrated implementation, the RF antenna110and the Faraday shield1206are embedded within a lower insulator1200. An upper insulator1202is positioned above the lower insulator1200, forming a space between the upper and lower insulators that defines a gas plenum1204. Also visible in cross section are gas through-holes1210that pass through the lower insulator1200, enabling process gases in the gas plenum1204to travel through the lower insulator1200into the process region over the wafer pedestal106.

FIG.12Billustrates a perspective view showing the stacking of components including the RF antenna110, in accordance with the implementation ofFIG.12A. As can be seen in this view, the RF antenna110is positioned over the Faraday shield1206, with the conductive lines of the RF antenna110running perpendicular to lines of the Faraday shield1206.

FIG.12Cillustrates an overhead view of the process chamber102, in accordance with implementations of the disclosure. As shown, the RF antenna110is positioned over the Faraday shield1206. In the implementation ofFIG.12C, the line pitch of the Faraday shield is smaller than that of the implementation shown atFIGS.12A and12B.

FIG.12Dillustrates a cross section view of an outer portion of the process chamber102, in accordance with the implementation ofFIG.12C. The gas plenum1204is shown between the upper insulator1202and the lower insulator1200. The illustrated cross section is along the direction of the conductive lines of the RF antenna110, and perpendicular to the direction of the lines of the Faraday shield1206.

FIG.12Eillustrates a cross section view of a portion of the process chamber102, in accordance with the implementation ofFIG.12C. The illustrated cross section is perpendicular to the lines of the Faraday shield1206. In the illustrated view, gas through-holes1210are shown, which are positioned so that process gas may travel between the lines of the Faraday shield1210.

FIG.12Fillustrates a cross section view of a portion of the process chamber102, in accordance with the implementation ofFIG.12C. The illustrated cross section is perpendicular to the lines of the RF antenna110. As shown, the gas through-holes1210are positioned so that process gas may travel between the conductive lines of the RF antenna110.

FIG.13Aillustrates an RF antenna110in accordance with implementations of the disclosure. In the illustrated implementation, the RF antenna110includes parallel and equally spaced conductive lines1300,1302,1306,1308,1310, and1312. The conductive lines of the RF antenna110are powered from the same side of the RF antenna110and split RF power from a power source118. The conductive lines are grounded on the opposite side of the RF antenna110. Hence, currents run in parallel in the same direction along the lines1300,1302,1306,1308,1310, and1312.

FIG.13Billustrates an RF antenna110in accordance with implementations of the disclosure. In the illustrated implementation, the RF antenna110includes parallel and equally spaced conductive lines1314,1316,1320,1322,1326, and1328. Conductive lines1314and1316are connected in series by a connector1318; conductive lines1320and1322are connected in series by a connector1324; conductive lines1326and1328are connected in series by a connector1330. As shown, the conductive lines are powered and grounded from the same side of the RF antenna110. More specifically, the conductive lines1314,1320, and1326are powered by an RF power source118, and the conductive lines1316,1322, and1328are connected to ground, along the same side of the RF antenna110.

A problem for achieving high density plasma with inductively coupled plasma systems is that the voltage and/or power required to achieve the desired high density of plasma is too high. Having too high a voltage and/or power can cause multiple problems. Generally speaking, the plasma sheath forms the outermost part (e.g. about 1 mm thickness) of the plasma skin (e.g. about 1 cm thick). As the electric field in the plasma sheath just below the dielectric window is generally perpendicular to the plane of the dielectric window (whereas the electric field in the plasma skin is generally parallel to the plane of the dielectric window) the high voltage and/or power will result in bombardment of the dielectric window with ions, which can result in contamination of the wafer surface. This further wastes energy by generating heat and also consumes the power being applied, so that it is wasted instead being used for inductive heating of the plasma, rendering the process very inefficient. Additionally, high voltage and/or power may stress related power componentry, producing excessive wear, reducing lifetime, and may even trigger arcing of the match circuitry.

In some implementations, it is contemplated how to place the counter-current inductor lines the closest to the plasma while having the least plasma-to-inductor voltage and the most inductor-current. Accordingly, with continued reference to the implementation ofFIG.5, for an RF antenna defined having a single continuous length, the following is considered:

VS=I0⁢τCS=I0⁢ω⁢LS

where VSis the RF antenna's peak-voltage,

I0is the inductor peak current,

LSis the RF antenna's inductance,

ω is the angular frequency and τ is the angular period.

It will be noted that for an unbalanced ICP where the inductor-end is tied directly to ground without CS2, its phase-cap was C=CS/2 and the unbalanced ICP peak-voltage is double that of the balanced ICP.

On the lowest order, a constant I0keeps a constant nefor the ICP. Thus, a challenge is how to maintain a constant I0while keeping VSas low as possible. If VScan be kept under 400V at maximum power, then Faraday shield may not be needed.

As noted previously, by way of example without limitation, an RF antenna having the following dimensions is considered: 17″ line-segment (18 lines), 1″ line-to-line, 0.25″ line width.

One strategy for reducing the voltage is to divide the RF antenna into multiple segments, such as indicated by the implementation ofFIG.7. Considering such an implementation, then the following is considered:

let, L=Serpentine-cell's inductance,

L0=Serpentine-cell Array's inductance,

Then, it is approximately correct to have,

L=LS9L0=L9=LS8⁢1

and the matcher would then have,

C0=8⁢1⁢CSω=2L0⁢C0

and then the inductor's peak-voltage becomes,

V0=9⁢I0⁢τC0=9⁢I0⁢ω⁢⁢L0V0=I0⁢τ9⁢CS=I0⁢ω⁢LS9V0=VS9

Thus, by dividing the RF antenna into nine segments, the voltage is approximately divided by nine, while each line segment still passes the same current, I0. A possible complication is that the phase-caps of the matcher will need to be 81 times larger than that of the matcher for the RF antenna having only a single continuous length. The 400V peak-voltage for the 9-segment array RF antenna is equivalent to 3600V for the single continuous length RF antenna, and that is equivalent to 7200V unbalanced ICP. A ±7200V peak-voltage of an unbalanced ICP is typically associated with 5 kW to 10 kW of RF power.

While a 400V peak-voltage is achievable as discussed above, such a voltage and power requirement may still be too high. Another way to reduce the voltage is to couple the RF power through a grounded counter-current inductor as discussed below.

FIG.14Aillustrates an overhead view of an RF antenna disposed over a grounded counter-current inductor for coupling RF power into a chamber, in accordance with implementations of the disclosure. The RF antenna110in accordance with the implementation ofFIG.7(including segments700,702,704,706,708,710,712,714, and716) is shown disposed over a grounded (counter current) inductor1400. The RF antenna110is positioned above the dielectric window, while the grounded inductor1400is positioned below the dielectric window in the process region of the chamber. Broadly speaking, the RF antenna110is powered as previously discussed and induces currents in the grounded inductor1400, which in turn inductively generate the plasma in the process region.

As shown, the grounded inductor1400includes grounded inductor lines1402that are positioned directly beneath the conductive lines of the RF antenna110.

FIG.14Billustrates a cross section view of the grounded inductor1400, in accordance with implementations of the disclosure. The conductive lines718and720of the segment700of the RF antenna110are shown disposed over the dielectric window150, and separated therefrom by an air-gap of approximately 0.050 inch (0.13 cm) in some implementations. The grounded inductor lines1402aand1402bare aligned below the conductive lines718and720, respectively. In some implementations, the dielectric window150has a thickness of approximately 0.125 inch (0.32 cm). At such a thickness, the dielectric window may not be structurally strong enough to withstand the difference in pressure when the chamber is operated under vacuum conditions. Therefore, the grounded inductor lines1402of the grounded inductor1400may further serve to support the dielectric window150, enabling the dielectric window150to be constructed with low thickness (e.g. less than about 0.25 inch (0.6 cm) in some implementations).

In some implementations, a typical current flowing in a hairpin segment such as segment718of the RF antenna110is about 80 amps. However, because the segment is thin, it has a certain inductance. The grounded inductor line1402ahas a much larger cross sectional area so its inductance, in some implementations, is about four times lower than that of the segment718. So assuming conservation of flux for the sake of simplification, then the current in the grounded inductor line1402abecomes about four times higher than the current in the segment718. So the 80 amps flowing in the segment718becomes approximately 320 amps flowing in the grounded induction line1402a. And with the current amplified four times, then the voltage in the grounded induction line1402ais reduced by a factor of four.

Thus, the voltage can be reduced both by the segmentation of the RF antenna110and by using the grounded inductor1400. By way of example without limitation, at for example, 3 kW of power and 80 amps current, the voltage in a single continuous line RF antenna design (as in implementation ofFIG.5) may be in the range of about 8000 V. However, by splitting the RF antenna into, for example, a nine segmented hairpin design (as in implementation ofFIG.7), the voltage is approximately divided by the number of segments, so instead of 8000 V, the voltage in the segments is reduced (divided by nine) to approximately 900 V. And using the grounded inductor1400e, because the inductance is lower, the current is further amplified about four times from 80 to 320 Amps, and when the current is amplified four times, the voltage drops four times. Thus, the 900 V in the RF antenna110drops down to a voltage in the grounded inductor1400in the range of about 200 to 300 V.

The grounded inductor lines1402are immersed in the plasma, so the magnetic flux generated by current in the grounded inductor lines1402will be strongly coupled to the plasma. A typical inductor is much further away from the plasma, and typically separated by a thicker window. However, implementations of the present disclosure provide for the inductor line to be located in the plasma with current amplified so the voltage drops.

In some implementations, the RF antenna110is powered with approximately 2 to 5 kW of power, to produce a high density plasma.

As shown, in some implementations, the grounded inductor lines1402have a cross-sectional width of about 0.4 inch (1 cm) and a cross-sectional height of about 0.5 inch (1.3 cm). The pitch of the grounded inductor lines1402is the same as that of the conductive lines of the RF antenna110. Hence, in some implementations, the pitch of the grounded inductor lines1402is about 1 inch (2.5 cm).

In some implementations, a frame1404of the grounded inductor1400is formed as a one-piece structure that forms part of the sidewalls of the process chamber, acting as a vacuum wall to structurally maintain the integrity of the chamber under vacuum. A gasket1406is embedded in the frame1404to provide a seal between the dielectric window150and the frame1404of the grounded inductor1400. It will be appreciated that the inductor lines1402of the grounded inductor1400are attached at their ends to the frame1404, and in some implementations, are formed as a continuous structure with the frame1404.

It will be appreciated that the grounded inductor1400also serves as the Faraday shield, and thus there is no need for an additional Faraday shield to block the electric field from the RF antenna110, as the electric field is absorbed by the grounded inductor1400.

Additionally, in some implementations, the gap between the conductive lines of the RF antenna110and the grounded inductor lines of the grounded inductor1400can be configured to be the smallest possible to maximize inductive coupling while also being large enough to support a stray capacitance that can facilitate the series resonance.

FIG.14Cis a graph illustrating the relative phases of the currents in the structures of the plasma processing system, in accordance with the implementation ofFIG.14A. As shown, but without being bound by any particular theory of operation, it is submitted that in some implementations, the current in the grounded induction lines of the grounded inductor1400is approximately 90 degrees phase-shifted from the current in the respective conductive lines (hairpin current) of the RF antenna110. Further, the current in the plasma is submitted to be approximately 90 degrees phase-shifted from the current in the grounded inductor1400. Thus, the current in the plasma is submitted to be approximately 180 degrees phase-shifted from the current in the RF antenna110.

FIG.14Dillustrates a cross-section view of a grounded inductor line1402of the grounded inductor1400, in accordance with the implementation ofFIG.14A. As shown, in some implementations, the structure includes an aluminum central body1410, which provides suitable strength to support the dielectric window150during vacuum processes. However, while, aluminum is strong, it is not a good RF conductor. Therefore, the aluminum body1410can be coated with a highly conductive material such as Cu or Ni—Ag—Ni, to form a conductive coating1412over the central body1410. Then a protective coating1414can be deposited over the conductive coating1412, the protective coating1414consisting of a material that will be chemically non-reactive during process conditions, such as yttrium oxide (Y2O3).

Additionally, in some implementations, cooling channels1420can be defined within the grounded inductor lines1402, to enable a coolant to be circulated within the grounded inductor1400and provide for temperature control of the grounded inductor1400.

Further, in some implementations, gas channels1422can be run within the grounded inductor lines1402, which allow process gases to be fed into the chamber through the grounded inductor1400. Process gases can be routed into the gas channels1422and distributed into the process region through exit holes1424. The integration of a showerhead is generally always a problem for any system with a dielectric window. However, the grounded inductor1400disclosed herein provides a metal piece within which channels for liquid cooling and process gases can be run, so that the dielectric window150does not need to have any holes as in other systems.

FIGS.15A and15Billustrate overhead and cross-section views, respectively, of a grounded inductor1500, in accordance with implementations of the disclosure. The grounded inductor1500ofFIGS.15A and15Bdiffers from the grounded inductor1400ofFIGS.14A and14Bprimarily in that the width of the grounded inductor lines1502is widened to have a width of approximately 0.8 inch (2 cm).

In existing ICP systems, it is generally desirable to have the Faraday shield oriented with lines running perpendicular to the inductor lines, and for the Faraday shield to have gaps so that magnetic flux to come through the Faraday shield into the process region. However, in the present design of the grounded inductor structure, it is desired to not have any magnetic flux from the RF antenna110to come in to the plasma. Rather, it is desirable to have the magnetic flux induce electric field above and below.

For the currents indicated by the X and the dot, indicating the current traveling in/out of the page, respectively,

∮E·dl=-ddt⁢∮B·dS⁢&⁢⁢J=σ⁢⁢E

J is current; sigma is conductivity; E is the electric field.

The grounded inductor1400is in some implementations, aluminum coated with copper (Cu) (as noted above) which has significantly better conductivity than the plasma. Thus, the flux of the RF antenna110would not substantially generate plasma current, as the current in the RF antenna110would principally become current in the copper of the grounded inductor1400. Thus the magnetic flux by the RF antenna110is substantially completely blocked by the grounded inductor lines. In some implementations, the gap between the grounded inductor lines can be a very small gap, e.g. less than about 0.5 inch (1.3 cm) in some implementations, about 0.2 inch (0.5 cm) in some implementations.

The proximity of the grounded induction lines (e.g., 0.2″) could force a ˜90° line-to-line current phase; its effect of enhancing “spatial stochastic” heating is discussed further below. The proximity also increases counter-current mutual induction resulting in a reduced inductance for the grounded induction line and that, reduces the peak voltage on the grounded induction line for a given current. The wider grounded induction line could also benefit the local plasma-density uniformity.

FIG.16illustrates a single hairpin counter-current inductor segment, in accordance with implementations of the disclosure. The segment1600as shown can be part of an array of such segments organized to form a counter-current inductor RF antenna110in accordance with implementations discussed above. An issue to consider is the precise current phase along the two conductive lines of the segment1600, indicated as line-1and line-2in the illustrated implementation.

Without being bound by any particular theory of operation, it is nonetheless posited that each ladder piece is likely not a uniform-current inductor. For line-to-line induction is believed to play a part in affecting the current phase. A graph1602illustrates by way of example without limitation, a 90 degree line-to-line current phase, that is believed to occur if line-to-line induction dominates. However, it is noted that if line-to-line conduction (real current) dominates, then the line-to-line current phase is 180 degrees, as the 180 degree direction change forced by the hairpin turn geometry will produce this.

In view of both line-to-line conduction and induction effects on current phase, it is therefore possible that perhaps the line-to-line current phase is a mixture from 90 degrees to 180 degrees varying along the length of a line to the current/voltage nodes.

FIG.17illustrates the effect of 90 degree line-to-line phased spatial-alternating plasma-skin induction currents, in accordance with implementations of the disclosure.

∇XE is the highest within Δx˜1 mm (simply due to ωB in Δx) and it will lead to “spatial” stochastic collisionless heating of the electrons as the electrons drift across Δx. In the absence of Landau damping and cyclotron resonance, such spatial stochastic collisionless heating occurs when electrons drift across Δx under a coincident phase condition. If the line-to-line phase were 180°, such coincident phase is very small. However, for the 90° line-to-line phase, such coincident phase is π⇒½ the time collisionless heating occurs. If the plasma is collisional, such a spatial stochastic process simply enhances ionization through collisional relaxation.

Thus, the effect of a 90 degree line-line current phase, if it exists, is enhanced ionization in addition to EEDf mixing among regions under the lines which normally occur even in the pure 180 degree condition.

FIG.18Aillustrates an overhead view of an RF antenna1800having a series serpentine configuration, in accordance with implementations of the disclosure. The RF antenna has an inductance of 2.4 μH, a 0.25 inch line width, and the parallel lines are equally spaced and have a 1 inch pitch.

FIG.18Bis a graph showing ion density as a function of lateral position for a plasma generated using RF antenna1800under various powers. The lateral position is the position along a center line in the chamber running perpendicular to the lines of the RF antenna. In the illustrated implementation, results are shown for a 30 cm distance that is equivalent to measuring edge-to-edge across a 300 mm wafer plane. Ion density was measured using a moving Langmuir probe. Plasma was generated with 50 mT Ar, in a chamber having a 2 inch vertical gap from the dielectric window to the wafer plane.

The curves1810,1812,1814,1816,1818, and1820correspond to results for power levels of 500 W, 1000 W, 1500 W, 2000 W, 2500 W, and 3000 W, respectively.

In the following disclosure, several different examples of RF antenna configurations are shown and tested. The inductor lines generally have a height of approximately ½ inch and a width of approximately ⅛ inch. However it will be appreciated that in other implementations the height and width of the inductor lines may vary. Broadly speaking, an inductor line height greater than its width can be beneficial to reduce capacitive coupling versus inductive coupling. For purposes of experimentation, RF power was applied at a frequency of 13.56 MHz. However, it will be appreciated that in other implementations the frequency of the power may vary, e.g. in a range of about 400 kHz to about 2 MHz.

FIG.19Aschematically illustrates an RF antenna having five hairpin segments1900,1902,1904,1906, and1908. The segments are arranged so that when powered, the RF antenna operates a counter-current inductor.

FIG.19Billustrates an overhead view of an RF antenna in accordance with the implementation ofFIG.19A, including five hairpin segments1910,1912,1914,1916, and1918, that form a counter-current inductor.

FIG.20Aillustrates a single hairpin element2000having a 1.5 inch spacing between lines, in accordance with implementations of the disclosure.

FIG.20Bis a graph of ion density versus lateral position for a plasma generated using the single hairpin element2000. The curves2010and2012illustrate results at 500 W and 1000 W, respectively.

FIG.20Cis a graph showing normalized density versus normalized power for the results shown atFIG.20B.

FIG.21Aillustrates a perspective view of a single hairpin element2100with a 0.125″ spacing introduced between the antenna and the dielectric window2102to reduce capacitive coupling. As shown, the spacing was accomplished by using spacers2104and2106mounted on the dielectric window2102. The thickness of the dielectric window2102is approximately ¾ inch.

FIG.21Bis a graph of ion density versus lateral position for a plasma generated at 250 mT Ar using the single hairpin element2100with the 0.125 inch spacing off the dielectric window. The curves2110,2112,2114, and2116illustrate results at 500 W, 750 W, 1000 W, and 1250 W, respectively.

FIG.22Aschematically illustrates a single hairpin element2200having a 3 inch spacing.

FIG.22Bis a graph of ion density versus lateral position for a plasma generated at 250 mT Ar using the single hairpin element2200. The curves2210,2212,2214, and2216illustrate results at 500 W, 750 W, 1000 W, and 1250 W, respectively.

FIG.23Aschematically illustrates an RF antenna consisting of two segments2300and2302, having a line spacing of 2.5″/2.5″/2.5″ as shown, and configured as a counter-current inductor.

FIG.23Billustrates an overhead view of an RF antenna having segments2310and2312, in accordance with the implementation ofFIG.23A.

FIG.23Cis a graph of ion density versus lateral position for a plasma generated at 250 mT Ar using the RF antenna ofFIG.23B. The approximate lateral locations of the antenna lines are shown at reference2320. The curves2322,2324,2326, and2328illustrate results at 500 W, 750 W, 1000 W, and 1250 W, respectively.

FIG.24Aschematically illustrates an RF antenna consisting of two hairpin segments2400and2402, having a line spacing of 2.5″/2.5″/2.5″ as shown, and configured as a partially parallel-current and partially counter-current inductor. As can be seen, the segments are configured and arranged so that within a single hairpin segment, current in adjacent lines runs in opposite directions, whereas between the two hairpin segments, current in the adjacent lines runs in the same direction. In some embodiments, the separation between the inner segments of the hairpin conductive lines can be adjusted to be increased or decreased as a tuning knob, to influence uniformity across the wafer. In the example ofFIG.24A, two hairpin conductive lines are shown. In other embodiments, additional hairpin conductive lines can be added, e.g., four hairpin conductive lines. The connections of power and ground to each hairpin conductive line can be made to set whether the current in adjacent inner lines run in the same direction or in opposite directions. In other cases, the power source connected to each segment can be separately controlled, e.g., to provide different power, voltage, and/or frequency to each hairpin conductive line. In this manner, not only can the structural placement of the hairpin conductive lines be set at different separations, but the power/current provided to each segment can also be individually set or dynamically adjusted to achieve the desired uniformity profiles. By way of example,FIGS.31C and32Cshow how uniformity can be achieved by the set relative orientation of the hairpin conductive lines, e.g., relative to each other, and the connections to the RF power source and ground.

FIG.24Billustrates an overhead view of an RF antenna having segments2410and2412, in accordance with the implementation ofFIG.24A.

FIG.24Cis a graph of ion density versus lateral position for a plasma generated at 120 mT Ar using the RF antenna ofFIG.24B. The approximate lateral locations of the antenna lines are shown at reference2420. The curves2422,2424,2426, and2428illustrate results at 500 W, 750 W, 1000 W, and 1250 W, respectively.

FIG.25Aschematically illustrates an RF antenna consisting of two hairpin segments2500and2502, having a line spacing of 2.5″/3.5″/2.5″ as shown, and configured as a partially parallel-current and partially counter-current inductor. The implementation ofFIG.25Ais similar to that ofFIG.24A, but with a wider center spacing.

FIG.25Billustrates an overhead view of an RF antenna having segments2510and2512, in accordance with the implementation ofFIG.25A.

FIG.25Cis a graph of ion density versus lateral position for a plasma generated at 250 mT Ar using the RF antenna ofFIG.25B. The approximate lateral locations of the antenna lines are shown at reference2520. The curves2522,2524,2526, and2528illustrate results at 500 W, 750 W, 1000 W, and 1250 W, respectively.

FIG.26Aschematically illustrates an RF antenna consisting of two hairpin segments2600and2602, having an even line spacing of 3.5″/3.5″/3.5″ as shown, and configured as a partially parallel-current and partially counter-current inductor. The implementation ofFIG.26Ais similar to that ofFIG.25A, but with a wider even spacing.

FIG.26Billustrates an overhead view of an RF antenna having segments2610and2612, in accordance with the implementation ofFIG.26A.

FIG.26Cis a graph of ion density versus lateral position for a plasma generated at 250 mT Ar using the RF antenna ofFIG.26B. The curves2622,2624,2626, and2628illustrate results at 500 W, 750 W, 1000 W, and 1250 W, respectively.

FIG.27Aschematically illustrates an RF antenna consisting of several lines2700,2702,2704, and2706, connected in parallel, and having a line spacing of 2.5″/3.5″/2.5″ as shown, and configured as an anti-counter current array/inductor or parallel-current array/inductor. That is, when the RF antenna is powered, the current in the inductor lines runs parallel in the same direction. The implementation ofFIG.27Ais similar to that ofFIG.25Ain terms of line spacing, but with complete parallel current as noted.

FIG.27Billustrates an overhead view of an RF antenna having lines2710,2712,2714, and1716, in accordance with the implementation ofFIG.27A.

FIG.27Cis a graph of ion density versus lateral position for a plasma generated at 250 mT Ar using the RF antenna ofFIG.27B. The approximate lateral locations of the antenna lines are shown at reference2720. The curves2722,2724,2726,2728, and2730illustrate results at 500 W, 750 W, 1000 W, 1250 W, and 1500 W, respectively.

FIG.28Aschematically illustrates an RF antenna having three hairpin segments2800,2802, and2804, having an even line spacing of two inches as shown, and configured as a counter current inductor.

FIG.28Billustrates an overhead view of an RF antenna having hairpin segments2810,2812, and2814, in accordance with the implementation ofFIG.28A.

FIG.28Cis a graph of ion density versus lateral position for a plasma generated at 250 mT Ar, 1000 W, using the RF antenna ofFIG.28B. The curves2820and2822illustrate results at 20% and 45%, respectively.

FIG.29Aschematically illustrates an RF antenna consisting of three hairpin segments2900,2902, and2904, having an even spacing of two inches as shown, and configured as a partially parallel-current and partially counter-current inductor.

FIG.29Billustrates an overhead view of an RF antenna having segments2910,2912, and2914, in accordance with the implementation ofFIG.29A.

FIG.29Cis a graph of ion density versus lateral position for a plasma generated at 250 mT Ar using the RF antenna ofFIG.29B. The curves2922,2924,2926, and2928illustrate results at 500 W, 750 W, 1000 W, and 1250 W, respectively.

FIG.30Aillustrates an overhead view of an RF antenna consisting of three hairpin segments3010,3012, and3014, having an even spacing of two inches as shown, and configured as a counter-current inductor, but with an alternating reverse setup of the hairpin segments, so that adjacent hairpin segments powered/grounded from opposite sides. The implementation ofFIG.30Ais similar to that ofFIG.28A and28B, except that the middle hairpin segment3002is powered and grounded from the opposite side when compared to the outer two hairpin segments3002and3004.

FIG.30Bis a graph of ion density versus lateral position for a plasma generated at 250 mT Ar using the RF antenna ofFIG.30A. The curves3022and3024illustrate results at 1000 W and 1500 W, respectively.

FIG.31Aschematically illustrates an RF antenna consisting of two hairpin segments3100and3102, having a line spacing of 2.5″/4.5″/2.5″ as shown, and configured as a partially parallel-current and partially counter-current inductor.

FIG.31Billustrates an overhead view of an RF antenna having segments3110and3112, in accordance with the implementation ofFIG.31A.

FIG.31Cis a graph of ion density versus lateral position for a plasma generated at 250 mT Ar using the RF antenna ofFIG.31B. The curves3122,3124,3126, and3128illustrate results at 500 W, 750 W, 1000 W, and 1250 W, respectively.

FIG.32Aschematically illustrates an RF antenna consisting of two hairpin segments3200and3202, having a line spacing of 2.5″/4.0″/2.5″ as shown, and configured as a partially parallel-current and partially counter-current inductor.

FIG.32Billustrates an overhead view of an RF antenna having segments3210and3212, in accordance with the implementation ofFIG.32A.

FIG.32Cis a graph of ion density versus lateral position for a plasma generated at 250 mT Ar using the RF antenna ofFIG.32B. The curves3222,3224,3226, and3228illustrate results at 500 W, 750 W, 1000 W, and 1250 W, respectively.

Table 1 below shows additional data analysis for the results illustrated atFIG.32C.

TABLE 1std devrangepoweraveragemaxstd devrange(−3pts)(−3pts)5004.35E+116.85E+1135%57%31%47%7506.03E+117.67E+1125%46%17%26%10008.46E+119.92E+1120%39%9%15%12501.18E+121.33E+1220%47%7%14%

FIG.33schematically illustrates an RF antenna consisting of two S-shaped (S-pin/mini-serpentine) segments3300and3302, having a line spacing of 2″/2″/3.5″/2″/2″ as shown, and configured as a partially parallel-current and partially counter-current inductor. Each of the S-pin segments is configured individually as a counter-current inductor. However, the adjacent ones of the lines of the segments3300and3302(innermost two adjacent lines) are configured for parallel current in the same direction.

FIG.34schematically illustrates an RF antenna consisting of four hairpin segments3400,3402,3404, and3406, and having an even line spacing of 1.5″, and configured as a partially parallel-current and partially counter-current inductor.

In some implementations, a controller is part of a system, which may be part of the above-described examples. Such systems can comprise semiconductor processing equipment, including a processing tool or tools, chamber or chambers, a platform or platforms for processing, and/or specific processing components (a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as the “controller,” which may control various components or subparts of the system or systems. The controller, depending on the processing requirements and/or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and/or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and/or load locks connected to or interfaced with a specific system.

Broadly speaking, the controller may be defined as electronics having various integrated circuits, logic, memory, and/or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and/or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some implementations, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and/or dies of a wafer.

The controller, in some implementations, may be a part of or coupled to a computer that is integrated with, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be in the “cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process. In some examples, a remote computer (e.g. a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and/or settings, which are then communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control. Thus as described above, the controller may be distributed, such as by comprising one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber.

Without limitation, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and/or manufacturing of semiconductor wafers.

As noted above, depending on the process step or steps to be performed by the tool, the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and/or load ports in a semiconductor manufacturing factory.

FIG.35Aillustrates an overhead view into a process chamber3500showing a configuration of an RF antenna3502, in accordance with implementations of the disclosure. The RF antenna3502is disposed over a dielectric window (not shown) and is configured to inductively generate plasma in the process chamber3500when powered. The RF antenna3502includes several conductive lines that are parallel to each other and coplanar (oriented along the same plane above the dielectric window of the process chamber). These include outer conductive lines3504aand3504b, and inner conductive lines3506aand3506b. In the illustrated implementation current flow in the inner conductive lines3506aand3506boccurs in the same given direction, while current flow in the outer conductive lines3504aand3504boccurs in the opposite direction.

The conductive lines3504a,3504b,3506a, and3506b, are substantially straight portions of the RF antenna. As shown, the conductive lines3504aand3506aare connected by a connecting portion3508a, and the conductive lines3504band3506bare connected by a connecting portion3508b, enabling current flow between the inner and outer conductive lines. The connecting portions function as turnarounds, so that current flow in the outer conductive lines flows in the opposite direction to current flow in the inner conductive lines.

The inner conductive lines3506aand3506bare spaced apart at a pitch spacing S1(center-to-center distance) of about 1 to 6 inches (about 2.5 to 15 cm) in some implementations, about 3 to 5 inches (about 7.5 to 12.5 cm) in some implementations, or about 4 inches (about 10 cm) in some implementations.

The adjacent outer and inner conductive lines3504aand3506a, as well as3504band3506b, are spaced apart at a pitch spacing S2(center-to-center distance) of about 2 to 6 inches (about 5 to 15 cm) in some implementations, about 2 to 3 inches (about 5 to 7.5 cm) in some implementations, or about 2.5 inches (about 6 to 6.5 cm) in some implementations.

In some implementations, the inner and outer conductive lines are configured to be substantially straight throughout the region that is over the wafer's surface. That is, relative to an axis that is orthogonal through the center of the wafer surface, the conductive lines extend in a substantially straight manner to a point that is at or beyond the radius of the wafer. In the illustrated implementation, the radius R1of the wafer is shown, and the radius R2of the connecting portions3508aand3508bis greater than the radius R1.

FIG.35Billustrates a perspective cutaway view of the process chamber3500, in accordance with implementations of the disclosure. As shown, the RF antenna3502is disposed over the dielectric window3510. In some implementations the thickness of the dielectric window3510is in the range of about 0.5 to 2 inches (about 1 to 5 cm). In some implementations the distance of the RF antenna3502from the dielectric window3510is about 0 to 0.5 inch (about 0 to 1.5 cm).

The RF antenna3502receives RF power from a generator3512through a match3514, which together define an RF source for the RF antenna. As shown, in some implementations the outer conductive lines3504aand3504bconnect to the RF source, or are positioned upstream (the RF feed side of the RF antenna) relative to the RF source, as compared to the inner conductive lines3506aand3506bwhich are positioned downstream relative to the RF source (the ground/return side of the RF antenna). In some implementations the inner conductive lines3506aand3506bconnect to a termination cap3516that includes a variable capacitor and connects to ground.

It is further noted that as shown in the illustrated implementation, the ends of the RF antenna3502are raised above the plane of the conductive lines. More specifically, the ends of the RF antenna on the feed side (ref.3518) serve to electrically link the outer conductive lines for connection to the same RF source. Similarly, the ends of the RF antenna on the ground/return side (ref.3520) link the inner conductive lines for connection to the same termination cap.

In an alternative implementation, the inner conductive lines are positioned upstream and connected to the RF source, and the outer conductive lines are positioned downstream and connected to the termination cap.

In the illustrated implementation the upstream and downstream ends of the RF antenna3502are joined so as to be powered by the same RF source and grounded through the same termination cap. However, it will be appreciated that in some implementations the upstream ends of the RF antenna3502can be powered by separate RF sources. Further, in some implementations the downstream ends of the RF antenna3502can be terminated by separate termination caps.

FIG.35Cillustrates a cutaway view of the process chamber3500along a plane perpendicular to the conductive lines of the RF antenna3502, in accordance with implementations of the disclosure.

FIG.36Aillustrates an overhead view into a process chamber3500showing a configuration of an RF antenna3600, in accordance with implementations of the disclosure.

FIG.36Billustrates a perspective cutaway view of the process chamber3500including the RF antenna3600, in accordance with implementations of the disclosure.

The RF antenna3600has a stacked configuration of conductive lines extending over the wafer region, such that in addition to the set of conductive lines shown and described in the RF antenna3502, the RF antenna3600additionally includes a second set of parallel conductive lines that are disposed directly over the first set of conductive lines. That is, there is RF antenna3600includes a bottom set of coplanar parallel conductive lines, and an upper set of coplanar parallel conductive lines that are respectively aligned over the conductive lines of the bottom set as shown.

In the illustrated implementation the RF antenna3600includes an upper set of coplanar and parallel conductive lines including upper inner conductive lines3602aand3602b, and upper outer conductive lines3606aand3606b. The RF antenna3600further includes a lower set of coplanar and parallel conductive lines including upper inner conductive lines3610aand3610b, and upper outer conductive lines3614aand3614b.

The upper inner conductive line3602aconnects via a connecting segment3604ato the upper outer conductive line3606a, which connects via a connecting segment3608ato the lower inner conductive line3610a, which connects via an additional connecting segment (not shown, directly below connecting segment3604a) to the lower outer conductive line3614a. In this manner, these lines and segments form a looped structure that substantially defines one half of the RF antenna3600. The other half of the RF antenna3600is similarly substantially defined by a similar looped structure, wherein the upper inner conductive line3602bconnects via a connecting segment3604bto the upper outer conductive line3606b, which connects via a connecting segment3608bto the lower inner conductive line3610b, which connects via an additional connecting segment (not shown, directly below connecting segment3604b) to the lower outer conductive line3614b.

In some implementations the wafer has a diameter of about 12 inches (about 30 cm) or a radius R1of about 6 inches (about 15 cm). Accordingly, the straight conductive lines may extend to or past the diameter of the wafer, so that the turns of the RF antenna are not substantially over the wafer. In some implementations the connecting segments are configured at a diameter of about 14 inches (about 35 cm) or a radius R2of about 7 inches (about 17.5 cm).

In the illustrated implementation, the upper inner conductive lines3602aand3602bare connected to an RF source3620, and are thus at the RF feed side of the antenna structure. The lower outer conductive lines3614aand3614bare connected to a termination cap3622, and are thus at the ground/return side of the antenna structure. In the illustrated implementation the ends of the upper inner conductive lines3602aand3602b, and the ends of the lower outer conductive lines3614aand3614b, are turned vertically upward out of the horizontal planes of the conductive lines to provide connection points for connection to the RF source3620and termination cap3622.

It is recognized that in the RF antenna3600the looped ends (turnaround segments) may cause some transformer effect. Therefore, in some implementations, this effect can be reduced by bending the end loops up at an angle (e.g. approximately 90 degree angle). This will also reduce the end loops' current induction into the chamber. Thus in some implementations, the RF antenna3600includes conductive lines that are connected in series by raised end loop connectors. For example, the conductive lines3602a,3606a,3610a, and3614aare connected in series by connectors3604a,3608a, and an additional connector (not shown) below connector3604a. The connectors can be configured as curved segments oriented along a plane that is substantially perpendicular to the horizontal plane(s) along which the conductive lines are oriented. Such connectors can define a current path, from one conductive line to another, that travels upward out of the plane of the conductive lines, and then travels downward back into the plane of the conductive lines. Similarly, the conductive lines3602b,3606b,3610b, and3614bare connected in series by connectors3604b,3608b, and an additional connector (not shown) below connector3604b, and the connectors can be similarly configured and define a current path as described above.

It will be appreciated that that such connectors and the conductive lines can be configured to maintain a predefined separation between the various lines. For example, the upper conductive lines3602aand3606amay extend to certain lengths (e.g. past the wafer edge) at which the raised connector3604ais formed. Whereas the lower conductive lines3610aand3614a, which are below the upper conductive lines3602aand3606a, may extend to lengths beyond those of the conductive lines3602aand3606a, at which the raised connector connecting the lower conductive lines is formed. In this way, a given spacing between the lines can be maintained while accommodating the raised end loop structure for both the upper and lower deck of the RF antenna.

In other implementations, each side of the RF antenna3600is independently powered, such that the upper inner conductive lines3602aand3602bare powered by separate RF sources. In some implementations, each side of the RF antenna3600is independently terminated, such that the lower outer conductive lines3614aand3614bare connected to separate termination caps.

FIG.36Dconceptually illustrates a cross section view of a portion of the dielectric window3510and the RF antenna3600, in accordance with implementations of the disclosure. The inner conductive lines3602aand3602bare horizontally separated at a pitch spacing S1as shown, which can be the same as that described above with respect to the RF antenna3502. As the inner conductive lines3602aand3602bare vertically stacked directly over the inner conductive lines3610aand3610b, the same pitch spacing S1applies to inner conductive lines3610aand3610b. The inner conductive line3602ais separated from the outer conductive line3606aat a pitch spacing S2, which can be the same as that described above with respect to RF antenna3502. The same pitch spacing S2also applies to the separation of inner conductive line3602bfrom outer conductive line3606b, as well as to the separation of inner conductive line3610afrom outer conductive line3614a, and the separation of inner conductive line3610bfrom outer conductive line3614b.

As shown, the dielectric window3510has a thickness H1. In some implementations, the thickness H1is in the range of about 0.25 to 1.5 inch (about 0.6 to 3.8 cm); in some implementations, H1is in the range of about 0.5 to 1 inch (about 1.3 to 2.5 cm); in some implementations, H1is about 0.75 inch (about 2 cm). The vertical distance H2from the bottom of the dielectric window3510to the lower set of conductive lines (3610a,3610b,3614a, and3614b) in some implementations can range from about 0.5 to 2 inches (about 1 to 5 cm). In some implementations the lower set of conductive lines are vertically separated from the top of the dielectric window3510by a vertical distance H3. In some implementations, H3is in the range of about 0 (i.e. no separation, with conductive lines touching dielectric window) to 0.5 inch (about 0 to 1.2 cm); in some implementations, H3is in the range of about 0 to 0.25 inch (about 0 to 0.6 cm); in some implementations, H3is about 0.25 inch (about 0.6 cm). Generally, the closer the conductive lines to the dielectric window, the better the inductive coupling into the chamber, but also the greater the sputtering of the dielectric window.

The upper and lower conductive lines are vertically separated by a vertical distance H4. In some implementations, H4is in the range of about ⅛ to 1 inch (about 0.3 to 2.5 cm); in some implementations, H4is in the range of about 0.25 to 0.75 inch (about 0.6 to 2 cm); in some implementations, H4is about 0.5 inch (about 1.3 cm). Broadly speaking, closer vertical spacing between the conductive lines provides for greater induction but also increased risk of arcing.

The double stack configuration of the RF antenna3600provides advantages over a single level configuration (e.g. as demonstrated by RF antenna3502) in terms of ease of powering the RF antenna and induction efficiency for generating plasma. For with the single level configuration of RF antenna3502, a high current is required to drive both sides of the RF antenna3502. One possible solution is to use separate generators to drive each side of the RF antenna. Another possibility is to apply power at a high frequency (e.g. about 40 MHz). However, using additional generators or applying a high frequency requires additional and/or costly hardware, increasing expense.

The double stack configuration of the present implementation solves these problems by increasing the inductance of the RF antenna, thus reducing the current while increasing the voltage. Power loss (e.g. through inductive heating which wastes power) in inductively coupled plasma systems is proportional to the square of the current (follows I2R). Thus, doubling the current, as required by the single level configuration of RF antenna3502which splits power into two halves, results in four times the loss. But by employing the double stack configuration of RF antenna3600, it is possible to raise the inductance of the RF antenna3600, to enable running at half the current of the single level RF antenna3502. This produces a four-fold reduction in power loss (reduced by 75%) for RF antenna3600, and provides better distribution of power and more efficient inductive coupling of power into the process chamber to generate the plasma.

With the single level configuration of RF antenna3502, the current is higher, but the voltage is lower, so the danger of capacitive coupling is reduced. However, it is desirable to achieve some capacitive coupling for purposes of plasma ignition. Thus, sufficient voltage is sought to ignite the plasma, while less voltage is sought once running to provide for more efficient inductive power coupling. The double stack configuration of RF antenna3600can also provide solutions to this issue because the bottom level of the RF antenna can shield high voltage from the upper level. The termination capacitance can be tuned so that there is sufficient voltage to ignite the plasma, but once running under steady state, while the upper level is at a higher voltage, the lower level is at a lower voltage. Each turn of the RF antenna is like a voltage divider, so that there may be twice as much voltage on the top versus the bottom, and this allows for the high voltage to be kept away from the dielectric window3610. High voltage in proximity of the dielectric window may sputter the dielectric window, and thus it is desirable to keep high voltage away from the dielectric window.

FIGS.37A,37B,37C, and37Dschematically illustrate various configurations of powering and terminating the RF antenna, in accordance with implementations of the disclosure.FIG.37Aillustrates the RF antenna3600being powered by a single RF source3620, and terminated by a single termination cap3622. In the illustrated implementation, the RF antenna3600is schematically represented as a pair of inductors that split power from the RF source3620, which includes a generator3700(e.g. oscillator) coupled to a match3702. On the downstream side, both inductors of the RF antenna3600terminate to the termination cap3622, which includes a variable capacitor coupled to ground.

FIG.37Billustrates the RF antenna3600wherein each half is powered by a separate RF source. More specifically, one coil (one inductor) of the RF antenna3600is powered by an RF source3710, including a generator3712coupled to a match3714. The other coil of the RF antenna3600is powered by an RF source3716, including a generator3718coupled to a match3720. In the illustrated implementation, both coils are connected to the same termination cap3622, which includes a variable capacitor coupled to ground. It will be appreciated that the separate RF sources can be individually tuned to provide a desired power distribution through the two sides of the RF antenna3600.

FIG.37Cillustrates the RF antenna3600being powered by a single RF source3620, and terminated by separate termination caps3720and3722. Each termination cap includes a variable capacitor coupled to ground. It will be appreciated that each termination cap can be adjusted/tuned to provide for balanced distribution of voltage/current through the two inductor halves of the RF antenna3600.

FIG.37Dillustrates the RF antenna3600being powered by separate RF sources3710and3716, and terminated by separate termination caps3720and3722. In this configuration, both the upstream and downstream sides of each inductor half of the RF antenna3600can be tuned to provide optimal power distribution.

It will be appreciated that the RF power applied to the antenna can be tuned to a desired state. For example, in some implementations the RF power is configured to achieve running under a balanced condition, so as to minimize capacitive coupling (thereby minimizing sputtering of the dielectric window). In such a state, the RF power is tuned so that a node (zero-voltage condition) exists at approximately halfway around the turn of the coil that is nearest the dielectric window. In the case of a single stack design as described with reference toFIGS.35A-35C, the RF power would be tuned so that nodes exist along the connecting portions3508aand3508b. Whereas in the case of a double stack design as described with reference toFIGS.36A-36C, the RF power would be tuned so that nodes exist along the connecting segments that are below the connecting segments3604aand3604b(not shown, as noted above). It is noted that when capacitive coupling is minimized, plasma ignition may become more difficult. Therefore in some implementations the RF power may be tuned to permit an amount of capacitive coupling sufficient to achieve plasma ignition under desired conditions.

It will be appreciated that the antenna lines can be formed to have various kinds of cross-sectional shapes, in accordance with implementations of the disclosure. While various segments have been described, it will be appreciated that each half of the RF antenna3600can be formed from a single continuous length of conductive material that is bent/formed to have the desired antenna shape (e.g. double stacked shape having a double looped structure).FIG.38Aillustrates a portion of an RF antenna, such as one of the halves/sides of the RF antenna3600, that is formed as a continuous bent sheet/strip. In the illustrated implementation, the portions consists of a single strip of conductive material that has been bent to the desired shape, such that the cross-sectional shape is a vertically oriented (height greater than width) substantially rectangular shape.

FIG.38Billustrates a portion of an RF antenna formed as a continuous bent tube, in accordance with implementations of the disclosure.

FIG.38Cillustrates a portion of an RF antenna formed from a plurality of tubular fittings, such as a plurality straight tubular fittings and a plurality of curved tubular fittings, in accordance with implementations of the disclosure.

FIGS.39A,39B, and39Cillustrate overhead, perspective cutaway, and side cross-sectional views an RF antenna that is powered from the sides, in accordance with implementations of the disclosure. In the illustrated implementation, the RF antenna3900is similar in structure to the RF antenna3502described above, including two portions/sides/halves3902aand3902b, with each antenna portion including inner and outer conductive lines that are parallel and oriented along the same horizontal plane, extending over the wafer and to the edges of the wafer region. However, in the RF antenna3900, each outer conductive line is not continuous through the middle, but actually consists of two segments that are respectively connected to the RF source and to the termination cap/ground. The outer ends of these segments are connected, via connectors, to the adjacent inner conductive line, thereby forming a loop (from RF source to termination cap). Thus, current flow from the RF source begins from the side, through a side connector to one of the segments of the outer conductive line, through a connector to the inner conductive line, through another connector to the other segment of the outer conductive line, and through another side connector to a termination cap. It will be appreciated that though each half has been described as consisting of various segments, each half of the RF antenna3900can be formed from a single length of conductive material, such as a tube or sheet/strip.

While the RF antenna3900as shown and described consists of a single level structure, it will be appreciated that in other implementations, the RF antenna3900can have a double stack structure similar to that of RF antenna3600described above, with each half formed as a double looped structure with upper and lower conductive lines that are directly above/below one another, while also being powered/grounded from the side.

FIG.40conceptually illustrates an overhead view of an RF antenna having curved outer conductive lines, in accordance with implementations of the disclosure. In the illustrated implementation, the RF antenna4000includes inner conductive lines4002aand4002b, and outer conductive lines4004aand4004b. The inner conductive lines4002aand4002bare substantially straight, while the outer conductive lines4004aand4004bhave are substantially curved outward along the horizontal plane. In some implementations the RF antenna4000can have a double stack configuration including two loops that are vertically aligned.

FIG.41conceptually illustrates an overhead view of an RF antenna having curved inner and outer conductive lines, in accordance with implementations of the disclosure. In the illustrated implementation, the RF antenna4100includes inner conductive lines4102aand4102b, and outer conductive lines4104aand4104b. The inner conductive lines4102aand4102b, as well as the outer conductive lines4104aand4104bhave are substantially curved outward along the horizontal plane. In some implementations the RF antenna4100can have a double stack configuration including two loops that are vertically aligned.

FIG.42conceptually illustrates an overhead view of an RF antenna having adjustable line spacing, in accordance with implementations of the disclosure. As shown, the RF antenna4200includes inner conductive lines4202aand4202b, as well as outer conductive lines4204aand4204b. The inner and outer conductive lines are configured to be horizontally movable, so that the spacing between the lines is adjustable. In some implementations, an adjustment mechanism is provided at each end of the conductive lines to enable horizontal movement of the conductive lines. In the illustrated implementation, adjusters4206aand4206bare configured to enable horizontal adjustment of the conductive line4202a; adjusters4208aand4208bare configured to enable horizontal adjustment of the conductive line4202b; adjusters4210aand4210bare configured to enable horizontal adjustment of the conductive line4204a; adjusters4212aand4212bare configured to enable horizontal adjustment of the conductive line4204b.

The adjusters can include movement mechanisms (e.g. electric motors, stepper motors, servos, etc.) for moving the conductive lines. Further, the adjusters can include flexible conductive materials, such as cabling or flexible fittings, to accommodate the movement of the conductive lines. This may also ensure that the RF path length of the antenna does not substantially change when the conductive lines are moved to different positions.

It will be appreciated that as the conductive lines are moved, so the spacing between the conductive lines changes. Thus, the spacing S1between the inner conductive lines4202aand4202bis adjustable, as is the spacing S2between the inner and outer conductive lines4202aand4204a, and between the inner and outer conductive lines4202band4204b. In some implementations, by adjusting the layout of the conductive lines, the spacing between the inner and outer conductive lines4202aand4204acan differ from that between the inner and outer conductive lines4202band4204b. By enabling adjustment of the positioning of the conductive lines, it is possible to adjust/tune the spacing of the lines to achieve optimal plasma generation and process performance for given processes.

FIG.43is a simplified schematic diagram of a computer system for implementing implementations of the present disclosure. It should be appreciated that the methods described herein may be performed with a digital processing system, such as a conventional, general-purpose computer system. Special purpose computers, which are designed or programmed to perform only one function may be used in the alternative. The computer system4300includes a central processing unit (CPU)4304, which is coupled through bus4310to random access memory (RAM)4328, read-only memory (ROM)4312, and mass storage device4314. System controller program4308resides in random access memory (RAM)4328, but can also reside in mass storage4314.

Mass storage device4314represents a persistent data storage device such as a floppy disc drive or a fixed disc drive, which may be local or remote. Network interface4330provides connections via network4332, allowing communications with other devices. It should be appreciated that CPU4304may be embodied in a general-purpose processor, a special purpose processor, or a specially programmed logic device. Input/Output (I/O) interface4320provides communication with different peripherals and is connected with CPU4304, RAM4328, ROM4312, and mass storage device4314, through bus4310. Sample peripherals include display4318, keyboard4322, cursor control4324, removable media device4334, etc.

Display4318is configured to display the user interfaces described herein. Keyboard4322, cursor control (mouse)4324, removable media device4334, and other peripherals are coupled to I/O interface4320to communicate information in command selections to CPU4304. It should be appreciated that data to and from external devices may be communicated through I/O interface4320. The implementations can also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a wire-based or wireless network.

Implementations may be practiced with various computer system configurations including hand-held devices, microprocessor systems, microprocessor-based or programmable consumer electronics, minicomputers, mainframe computers and the like. The implementations can also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a network.

With the above implementations in mind, it should be understood that the implementations can employ various computer-implemented operations involving data stored in computer systems. These operations are those requiring physical manipulation of physical quantities. Any of the operations described herein that form part of the implementations are useful machine operations. The implementations also relates to a device or an apparatus for performing these operations. The apparatus may be specially constructed for the required purpose, such as a special purpose computer. When defined as a special purpose computer, the computer can also perform other processing, program execution or routines that are not part of the special purpose, while still being capable of operating for the special purpose. Alternatively, the operations may be processed by a general purpose computer selectively activated or configured by one or more computer programs stored in the computer memory, cache, or obtained over a network. When data is obtained over a network the data may be processed by other computers on the network, e.g., a cloud of computing resources.

One or more implementations can also be fabricated as computer readable code on a computer readable medium. The computer readable medium is any data storage device that can store data, which can be thereafter be read by a computer system. Examples of the computer readable medium include hard drives, network attached storage (NAS), read-only memory, random-access memory, CD-ROMs, CD-Rs, CD-RWs, magnetic tapes and other optical and non-optical data storage devices. The computer readable medium can include computer readable tangible medium distributed over a network-coupled computer system so that the computer readable code is stored and executed in a distributed fashion.

Although the method operations were described in a specific order, it should be understood that other housekeeping operations may be performed in between operations, or operations may be adjusted so that they occur at slightly different times, or may be distributed in a system which allows the occurrence of the processing operations at various intervals associated with the processing, as long as the processing of the overlay operations are performed in the desired way.

Accordingly, the disclosure of the example implementations is intended to be illustrative, but not limiting, of the scope of the disclosures, which are set forth in the following claims and their equivalents. Although example implementations of the disclosures have been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications can be practiced within the scope of the following claims. In the following claims, elements and/or steps do not imply any particular order of operation, unless explicitly stated in the claims or implicitly required by the disclosure.