Novel Inductively Coupled Plasma Apparatus with Faraday Shield

Abstract

This is an antenna assembly. The antenna assembly may include an antenna having a loop structure and a dielectric window adjacent to the antenna. The antenna assembly may also include a Faraday shield assembly positioned between the antenna and the dielectric window, the Faraday shield assembly being positioned at least partially around the antenna. The Faraday shield assembly may include a plurality of metal sections electrically insulated from each other, the plurality of metal sections being positioned in a plurality of shield pairs. Thus, the first and second metal sections of a given shield pair may be positioned opposite each other and electrically connected to each other.

Description

Technical Field

[0005] , ,

[0001] Cross - Reference to Related Applications

[0001] This application claims the benefit of priority of U.S. Patent Application No. 18 / 198,682, filed on May 17, 2023, which is hereby incorporated by reference in its entirety.

[0002]

[0002] This disclosure generally relates to processing apparatuses, and more specifically, to an antenna assembly for generating an inductively coupled plasma for use in a processing tool including a plasma - based ion source.

Background Art

[0003]

[0003] Currently, plasmas are used to process substrates such as electronic devices for applications such as substrate etching, layer deposition, ion implantation, and other processes. Some processing apparatuses employ a plasma chamber that generates a plasma that functions as an ion source for substrate processing. An ion beam can be extracted by an extraction assembly and directed towards a substrate in an adjacent chamber. This plasma can be generated in various ways.

[0004]

[0004] In various commercial systems, antenna structures are used to generate inductively coupled plasmas (ICPs). The antenna is excited using an RF power source and is used to couple to a chamber containing an ionized gas, where the antenna is separated from the ionized gas by a dielectric material such as a dielectric window or a dielectric shield.

[0005]

[0005] The RF current in the antenna induces a time - varying magnetic field B(t) that penetrates the plasma through the dielectric material. This B(t) flux induces an RF circular electric field E(t) and a current Ip(t) in the plasma. Plasma electrons acquire energy from the electric field, ionize gas neutrals, and thus maintain the plasma equilibrium density. In an ICP source, the plasma density is proportional to the antenna magnetic flux penetrating the plasma, and the RF power transfer efficiency depends on the magnetic coupling between the antenna and the plasma.

[0006]

[0006] To facilitate magnetic coupling, the antenna is positioned near the dielectric window, where capacitive coupling between the antenna and the dielectric, as well as adverse effects from the electric field-plasma sheath within the dielectric material, occur. Plasma ions reaching the plasma edge adjacent to the plasma sheath are accelerated by this electric field toward the dielectric material (e.g., the dielectric window), and this acceleration can generate enough energy for the plasma ions to cause erosion of the dielectric window and sputtering of the material. The erosion rate is highly dependent on the magnitude of the voltage generated across the plasma sheath. In many types of plasma processing equipment, the RF sheath voltage should be minimized to below a certain threshold level to avoid such adverse effects that occur when ions reach a certain threshold energy.

[0007]

[0007] In practical ICP sources, electrostatic (capacitive) coupling of the antenna to the plasma generates an additional RF voltage across the plasma boundary sheath (or simply "plasma sheath"). In certain antenna designs, such as the ends of a loop antenna with two ends, the plasma sheath voltage can become unacceptably high, exceeding the sputtering threshold and causing material to be sputtered from the vicinity of the dielectric window.

[0008]

[0008] Known ICP antenna designs may include a Faraday shield structure placed between the antenna and the dielectric window so that the Faraday shield plays a role in reducing the accompanying magnitude of capacitive coupling and RF sheath voltage. One drawback of using a Faraday shield is that it reduces magnetic coupling from the antenna to the plasma, and consequently reduces antenna power loss and power demand from the RF source.

[0009]

[0009] In relation to these and other considerations, this disclosure is provided. [Overview of the project]

[0010]

[0010] In one embodiment, an antenna assembly is provided. The antenna assembly may include an antenna having a loop structure and a dielectric window adjacent to the antenna. The antenna assembly may also include a Faraday shield assembly disposed between the antenna and the dielectric window, the Faraday shield assembly being at least partially disposed around the antenna. The Faraday shield assembly may include a plurality of metal sections electrically insulated from each other, the plurality of metal sections being arranged in a plurality of shield pairs. Thus, a first metal section and a second metal section of a given shield pair may be arranged opposite each other and electrically connected to each other.

[0011]

[0011] In another embodiment, a plasma source is provided. The plasma source may include a plasma chamber surrounding a plasma space containing plasma inside, and an antenna assembly disposed within or adjacent to the plasma chamber. The antenna assembly may include an antenna having a loop structure and a dielectric window adjacent to the antenna. The antenna assembly may also include a Faraday shield assembly disposed between the antenna and the dielectric window, the Faraday shield assembly being at least partially disposed around the antenna. The Faraday shield assembly may include a plurality of metal sections electrically insulated from each other, the plurality of metal sections being arranged in a plurality of shield pairs. Thus, the first and second metal sections of a given shield pair may be arranged opposite each other and electrically connected to each other.

[0012]

[0012] In further embodiments, a processing apparatus is provided. The processing apparatus may include a plasma chamber comprising a plasma chamber surrounding a plasma space for containing plasma inside, an extraction plate disposed on the side of the plasma chamber, and an antenna assembly disposed inside or adjacent to the plasma chamber. The antenna assembly may include an antenna having a loop structure, a dielectric window adjacent to the antenna, and a Faraday shield assembly disposed between the antenna and the dielectric window, the Faraday shield being at least partially disposed around the antenna. Thus, the Faraday shield assembly may include a plurality of metal sections electrically insulated from each other, the plurality of metal sections being arranged in a plurality of shield pairs. The processing apparatus may further include an RF assembly coupled to provide balanced RF voltage signals to a first end and a second end of the antenna. [Brief explanation of the drawing]

[0013] [Figure 1] An antenna assembly according to an embodiment of the present disclosure is shown. [Figure 2] The voltage distribution along an antenna assembly arranged according to an embodiment of this disclosure is shown. [Figure 3A] The end section view of an antenna assembly arranged according to an additional embodiment of the present disclosure is shown. [Figure 3B] Figure 3A shows a side view of the antenna assembly. [Figure 3C] Another antenna assembly according to an embodiment of the present disclosure is shown. [Figure 3D] Figure 3C shows a side view of the antenna assembly. [Figure 4] Plasma sources according to several embodiments of this disclosure are shown. [Figure 5A] This is a composite diagram showing an embodiment of an antenna circuit and the associated voltage distribution along the antenna of the antenna circuit. [Figure 5B]This is a composite diagram showing an embodiment of an additional antenna circuit and the associated voltage distribution along the antenna of the additional antenna circuit. [Figure 6A] An exemplary top view of a processing system according to another embodiment of the present disclosure is shown. [Figure 6B] Figure 6A shows a cross-sectional view of the end of the processing system. [Modes for carrying out the invention]

[0014]

[0024] The drawings are not necessarily to scale. The drawings are for illustrative purposes only and are not intended to depict any particular parameter of the disclosure. The drawings are intended to illustrate exemplary embodiments of the disclosure and should therefore not be considered limiting. In the drawings, similar numbering indicates similar elements.

[0015]

[0025] The apparatus, systems, and methods described herein will now be described in more detail below with reference to the accompanying drawings illustrating embodiments of the systems and methods. The systems and methods may be embodied in many different forms and should not be construed as being limited to the embodiments described herein. Rather, these embodiments provide a consistent and complete overview of the disclosure and fully convey the scope of the systems and methods to those skilled in the art.

[0016]

[0026] In relation to the shape, dimensions, and orientation of semiconductor manufacturing device components as seen in the drawings, terms such as “top,” “bottom,” “upward,” “downward,” “vertical,” “horizontal,” “lateral,” and “longitudinal” may be used herein to describe the relative arrangement and orientation of these components and their parts. Technical terms may include the words specifically mentioned, their derivatives, and words with similar meanings.

[0017]

[0027] Here, elements or operations following the words "one" or "a" (a, an) described in the singular are understood to potentially include multiple elements or operations as well. Further, references to "one embodiment" of the present disclosure are not intended to be construed as excluding the existence of additional embodiments that also incorporate the recited features.

[0018]

[0028] Herein, an antenna assembly for an improved inductively coupled plasma (ICP) plasma source is provided.

[0019]

[0029] Referring to the figures, FIG. 1 shows an antenna assembly according to an embodiment of the present disclosure. Antenna assembly 102 is shown in circuit configuration 100 that includes RF assembly 104 used to drive antenna 110. Antenna 110 is arranged to generate plasma within a plasma chamber (not shown) by generating an RF current in response to an RF signal received from RF assembly 104, similar to a known ICP antenna. Antenna 110 is arranged in a loop structure having a first leg 110A that extends in a direction parallel to antenna axis AX from a first end A of antenna 110 (for reference, antenna axis AX is aligned parallel to the X-axis of the illustrated Cartesian coordinate system). The loop structure of antenna 110 extends from a second end B and includes a second leg 110B that is also parallel to antenna axis AX, and further includes an intermediate section 110C that joins the first leg 110A and the second leg 110B.

[0020]

[0030] As shown in the figure, the antenna 110 is positioned near the dielectric window 112. The components of the dielectric window 112 may be formed from known dielectric materials. In some embodiments, the dielectric window 112 may be positioned as a dielectric cylinder surrounding the antenna 110 and having a cylindrical axis extending parallel to the antenna axis. In these embodiments, the dielectric window 112 (meaning the dielectric cylinder) may extend within the plasma chamber so that the antenna 110 is isolated from the gas species that generate the plasma surrounding the dielectric cylinder. In other embodiments, the dielectric window may be positioned as a planar plate located on the side of the plasma chamber, and the antenna 110 is positioned outside the plasma chamber.

[0021]

[0031] The antenna assembly 102 further includes a Faraday shield assembly 116 positioned between the antenna 110 and the dielectric window 112. According to various embodiments of the present disclosure, the Faraday shield assembly 116 may be positioned at least partially around the antenna 110. As shown in Figure 1A, the Faraday shield assembly 116 is formed from a plurality of metal sections, which are electrically insulated from each other by a dielectric gap 114, etc. These sections are indicated as section 116A, section 116B, section 116C, section 116D, section 116E, section 116F, section 116G, and section 116H. As further shown in Figure 1A, the metal sections are arranged in a plurality of shield pairs. In a given shield pair, such as represented by a shield pair 120 including sections 116A and 116B, the first metal section and the second metal section are positioned opposite each other. In addition, a first metal section, such as section 116A, and a second metal section, such as section 116B, are electrically connected to each other via an electrical conductor 122, which may be a metal wire or another electrical conductor. In this way, each section of the Faraday shield assembly 116 is electrically connected to one other section and electrically isolated from all other sections of the Faraday shield assembly.

[0022]

[0032] In various embodiments, the multiple metal sections constituting the Faraday shield assembly 116 are arranged coaxially around the antenna 110. In other words, a given metal section of the Faraday shield assembly 116 is arranged around a given leg of the Faraday shield assembly as a cylinder or partial cylinder having a cylindrical axis coinciding with the axis of a given leg. In other words, the metal sections of the Faraday shield assembly 116 are arranged equidistant from the antenna 110 along the length of the antenna 110. More specifically, the vertical distance D from the antenna 110 to the metal section is constant along the Faraday shield assembly 116. This relationship is shown in more detail with reference to Figures 3A and 3B, which are described below. The advantage of this relationship is that all metal sections of the Faraday shield assembly 116 exhibit equal capacitance.

[0023]

[0033] During operation, when an RF signal is applied to antenna 110, a voltage is generated along the length of antenna 110. This voltage can be expressed as an electrostatic or DC potential that varies along the length of the antenna. Because the Faraday shield assembly 116 is separated by electrically isolated shield pairs, the voltage along the Faraday shield assembly 116 is limited. Specifically, the intermediate regions between each metal section and the electrical conductor 122 float at an RF potential close to zero, making the metal sections virtually ground. This situation prevents the voltage in the sheath near the first end A and the second end B from becoming unacceptably high. It should be recalled that the plasma inside an ideal electrostatically isolated inductively coupled plasma does not acquire an RF potential toward the plasma boundary, i.e., toward the dielectric window and the chamber walls of the plasma chamber, due to the circular shape dimensions of the induced electric field.

[0024]

[0034] Furthermore, it should be noted that at the plasma edge, only an intrinsic DC potential of approximately 10V to 30V occurs across the plasma boundary sheath. While the RF voltage in the plasma chamber wall sheath can be minimized by applying balanced drive to the antenna, the voltage in the sheath occurring at the dielectric window boundary can still be significant in the absence of the Faraday shield assembly 116. This voltage is shown by the solid line in Figure 2, where the voltage can be maximum at the first end A and the second end C. The unshielded portions of the dielectric window 112 (meaning an antenna configuration without the Faraday shield assembly 116) near the first end A and near the second end B are exposed to the maximum voltage.

[0025]

[0035] However, as shown in Figure 2, if the Faraday shield assembly 116 is present, using an "n" shield pair reduces the maximum voltage of the antenna 110 by a factor of n. Specifically, the X-axis in Figure 2 represents the position along the antenna 110 from the first end A to the second end C. The representation in Figure 2 assumes the configuration of Figure 1, in which four shield pairs exist. The effect of a given shield pair is to limit the maximum voltage as shown, and the voltage along a given shield is represented by the sloping line segments. As shown, the voltage varies from a maximum positive value to a maximum negative value along each of the eight different line segments, representing the eight different metal sections of the Faraday shield assembly in Figure 1. However, the amplitude of the maximum voltage in each of these regions reaches just V / n or -V / n, where V represents the maximum voltage along the antenna if it were not protected by the Faraday shield assembly 116.

[0026]

[0036] Since the erosion rate of the dielectric window 112 may depend exponentially on the sheath voltage, any erosion will be significantly reduced by decreasing the maximum voltage by a factor of N.

[0027]

[0037] To maintain inductive coupling between antenna 110 and the plasma, various embodiments of the present disclosure position the Faraday shield assembly 116 or similar modifications such that the shielding surface perpendicular to the antenna radiated magnetic field is minimized. This situation is best achieved by positioning the shielding metal sections coaxially with the antenna legs, as described above with respect to Figure 1. An ideal coaxial screen positioned around a long radiating rod does not obstruct the antenna magnetic field. In the case of an antenna having a loop shape, as in this embodiment, some magnetic field distortion occurs due to the proximity of two different antenna legs. This magnetic field distortion effect can be minimized by positioning the metal sections so as to partially surround a given leg of antenna 110, such that no portion of the metal section exists within the region of each metal section facing the opposite leg. This configuration is shown in some of the following figures.

[0028]

[0038] Referring now to Figure 3A, an end section view of an antenna assembly arranged according to an additional embodiment of the present disclosure is shown. Figure 3B shows a side view of the antenna assembly of Figure 3A. In Figure 3A, a metal section 216A is shown, arranged as a partial cylinder having a cylindrical axis extending parallel to the X-axis. The metal section 216A may be arranged, for example, coaxially with the first leg 110A, surrounding the first leg 110A, where the axis of the first leg 110A coincides with the cylindrical axis of the metal section 216A. Similarly, other metal sections, such as metal section 216C, metal section 216E, and metal section 216G, may be arranged concentrically and coaxially with the first leg 110A, such that these additional sections are not visible in the view of Figure 3A. In the embodiment of Figure 3A, the metal section 216A has a C-shaped cross-section, with the open portion of C facing the opposite leg, i.e., the second leg 110B.

[0029]

[0039] Similar to metal section 216A, metal section 216B may be positioned to coaxially surround the second leg 110B, for example, when the axis of the second leg 110B coincides with the cylindrical axis of metal section 216B. Similarly, other metal sections such as metal section 216D, metal section 216F, and metal section 216H may be positioned concentrically and coaxially with the second leg 110B, such that these additional sections are not visible in the diagram of Figure 3A. In the embodiment of Figure 3A, metal section 216B also has a C-shaped cross-section, with the open portion of C facing the opposite leg, i.e., the second leg 110A. As previously stated, this “open” configuration of the metal sections of the Faraday shield assembly 216 tends to reduce magnetic field distortions arising from the proximal positions of the first leg 110A and the second leg 110B.

[0030]

[0040] Figure 3C shows another antenna assembly according to an embodiment of the present disclosure. Figure 3D shows a side view of the antenna assembly of Figure 3C. In this embodiment, antenna assembly 350 may be configured similarly to antenna assembly 102, and similar parts are labeled the same. In this embodiment, the Faraday shield assembly is provided to cover the relatively high-voltage portion of antenna 110, while the relatively low-voltage portion is closer to the exposed intermediate section B. In other words, the Faraday shield assembly 352 is positioned only around the first region of antenna 110, which is positioned toward the first end A and the second end B, and not around the second region of antenna 110, which is relatively closer to the intermediate section B. This embodiment has the advantage of making coupling to the plasma more efficient.

[0031]

[0041] Figure 4 shows a plasma source 400 according to several embodiments of the present disclosure. In this embodiment, the plasma source 400 drives an antenna assembly 402, which may be arranged similarly to antenna assembly 102 or antenna assembly 202. Thus, the antenna assembly 402 includes, as shown, a dielectric window 412 configured as a cylinder, an antenna 410 configured as a loop antenna, and a Faraday shield assembly 416 arranged in shield pairs in which a given metal section of each shield pair surrounds a first leg 410A or a second leg 410B. The dielectric window 412 can isolate the antenna 410 from the region surrounding the antenna assembly 402 in the plasma chamber 440. Thus, the plasma space 442 can define the plasma surrounding the antenna assembly 402 internally, such that gas species from the plasma space 442 are excluded from the interior of the cylinder formed by the dielectric window 412. During operation, when the plasma is ignited by the antenna assembly 402, an ion beam can be extracted through the opening 450 provided in the plasma chamber 440.

[0032]

[0042] In additional embodiments of the antenna assembly, the Faraday shield assembly is formed from a plurality of metal sections arranged generally as in the embodiments described above, with one modification being that the metal sections include an array of perforations (openings) to facilitate heat transfer and cooling of the antenna assembly. For example, referring to Figure 4, the Faraday shield assembly 416 may include openings in each metal shield. In addition, compressed air may be supplied that flows through the perforations in the metal sections and reaches the inner surface 212A of the dielectric window 212 (see Figure 3B).

[0033]

[0043] Figure 5A is a composite diagram showing an embodiment of the antenna circuit and the associated voltage distribution along the antenna of the antenna circuit, and Figure 5B is another composite diagram showing an embodiment of an additional antenna circuit and the associated voltage distribution along the antenna of the additional antenna circuit. In the embodiment of Figure 5A, a circuit configuration 500 is shown that includes a balanced network provided to generate a balanced drive voltage to the loop antenna 502. Thus, as shown, the antenna voltage at the first end A may be equal to and opposite to the voltage at the second end B. Note that due to imperfections in the balanced network, the paired shielded sections may be deviated from zero potential.

[0034]

[0044] In the circuit configuration 510 of the embodiment in Figure 5B, the split capacitor 514 is inserted into the loop antenna 512, mitigating this effect. The split capacitor 514 reduces the “hot spot” voltage at the first end A and the second end B by half (the voltage also increases in the middle section of the loop antenna 512, but the maximum voltage observed along the antenna 512 is reduced by half compared to the embodiment in Figure 5A). Furthermore, the deviation of the shield area potential of the Faraday shield assembly surrounding the loop antenna 512 is reduced by the same amount (see the s-slope segment representing the shield voltage as a function of position along the antenna).

[0035]

[0045] Figure 6A shows a top view of an exemplary processing system according to another embodiment of the present disclosure, and Figure 6B shows an end-face cross-sectional view of the processing system shown in Figure 6A.

[0036]

[0046] In one modification, system 600 includes the aforementioned components of the plasma source in Figure 4, with similar components labeled identically. In this figure, the processing chamber 602 is positioned to accommodate a substrate 604 that can be scanned along the Y-axis relative to the extraction opening 450. An ion beam 610 can be extracted from the plasma source 400, as shown in the end section view of Figure 6B. The ion beam 610 can be formed by two ion beamlets. These two ion beamlets strike the substrate 604 at a non-zero angle symmetrically with respect to the perpendicular (meaning the Z-axis) to the main plane of the substrate 604 (meaning the XY plane in this example). Thus, with the help of scanning the substrate holder 606 along the Y-direction, the entire substrate 604 can be exposed to an elongated inclined ribbon ion beam that covers the substrate along the x-axis (see Figure 6A). From the viewpoint of Figure 6B, it can be assumed that a blocker is present near the extraction opening 450, as in known extraction assemblies, causing the extraction of two symmetrically inclined beamlets. However, in some embodiments, only a single ion beamlet may be extracted from the extraction opening. During operation, the plasma source 400 does not cause substantial erosion of the dielectric cylinder of the antenna assembly 402 due to the improved design using a Faraday shield assembly arranged according to the embodiments described above.

[0037]

[0047] From the above perspective, this disclosure offers at least the following advantages. First, erosion of the RF window used with the ICP antenna can be reduced by using the new Faraday shield assembly. Second, the shield topology of the Faraday shield assembly according to this embodiment promotes more efficient antenna-to-plasma coupling and lower power loss.

[0038]

[0048] While specific embodiments of this disclosure are described herein, this disclosure is not limited thereto, for this disclosure is as broad as the art allows, and this specification can be interpreted in the same way. Therefore, the foregoing should not be construed as limiting. Accordingly, variable opacity Faraday shields of appropriate shape and topology can be used in combination with solenoidal antennas, flat spiral antennas, helical antennas, or circular antennas to mitigate the harmful effects of variable voltage distribution along their length. Those skilled in the art will envision such modifications within the scope of the claims and essence appended herein.

Claims

1. An antenna assembly, An antenna having a loop structure, A dielectric window adjacent to the aforementioned antenna, A Faraday shield assembly disposed between the antenna and the dielectric window, wherein the Faraday shield assembly is at least partially disposed around the antenna. Equipped with, The Faraday shield assembly comprises a plurality of metal sections electrically insulated from each other, the plurality of metal sections arranged in a plurality of shield pairs, the first metal section and the second metal section of a given shield pair being arranged opposite each other and electrically connected to each other, the antenna assembly.

2. The antenna has a first end and a second end positioned adjacent to the first end. The loop structure has a first leg portion extending from the first end parallel to the antenna axis, a second leg portion extending from the second end parallel to the antenna axis, and an intermediate section joining the first leg portion and the second leg portion. The antenna assembly according to claim 1, wherein the first metal section is arranged around the first leg and the second metal section is arranged around the second leg.

3. The antenna assembly according to claim 2, wherein the dielectric window is configured as a dielectric cylinder surrounding the antenna and has a cylinder axis extending parallel to the antenna axis.

4. The antenna assembly according to claim 1, wherein the plurality of metal sections are arranged coaxially around the antenna.

5. The antenna assembly according to claim 4, wherein the plurality of metal sections are arranged equidistant from the antenna along the length of the antenna.

6. The antenna assembly according to claim 4, wherein the plurality of metal sections have a C-shaped cross-section.

7. The antenna assembly according to claim 6, wherein the loop structure has a first leg and a second leg, and the open portion of the first metal section of the given shield pair faces the open portion of the second metal section of the given shield pair.

8. The antenna assembly according to claim 2, wherein the Faraday shield assembly is positioned around a first region of the antenna toward the first and second ends, and the Faraday shield assembly is not positioned around a second region of the antenna relatively close to the intermediate section.

9. It is a plasma source, A plasma chamber surrounds a plasma space containing plasma inside, An antenna assembly disposed within or adjacent to the plasma chamber, An antenna with a loop structure, A dielectric window adjacent to the antenna, and A Faraday shield assembly disposed between the antenna and the dielectric window, wherein the Faraday shield assembly is at least partially disposed around the antenna. Antenna assembly including Equipped with, The Faraday shield assembly comprises a plurality of metal sections electrically insulated from each other, the plurality of metal sections arranged in a plurality of shield pairs, the first metal section and the second metal section of a given shield pair being arranged opposite each other and electrically connected to each other, in a plasma source.

10. The antenna has a first end and a second end positioned adjacent to the first end. The loop structure has a first leg portion extending from the first end parallel to the antenna axis, a second leg portion extending from the second end parallel to the antenna axis, and an intermediate section joining the first leg portion and the second leg portion. The plasma source according to claim 9, wherein the first metal section is arranged around the first leg and the second metal section is arranged around the second leg.

11. The plasma source according to claim 10, wherein the dielectric window is configured as a dielectric cylinder surrounding the antenna and has a cylinder axis extending parallel to the antenna axis.

12. The plasma source according to claim 9, wherein the plurality of metal sections are arranged coaxially around the antenna.

13. The plasma source according to claim 12, wherein the plurality of metal sections are arranged equidistant from the antenna along the length of the antenna.

14. The plasma source according to claim 12, wherein the plurality of metal sections have a C-shaped cross-section.

15. The plasma source according to claim 14, wherein the loop structure has a first leg and a second leg, and the open portion of the first metal section of the given shield pair faces the open portion of the second metal section of the given shield pair.

16. The plasma source according to claim 10, wherein the Faraday shield assembly is positioned around a first region of the antenna toward the first and second ends, and the Faraday shield assembly is not positioned around a second region of the antenna relatively close to the intermediate section.

17. Processing apparatus, A plasma chamber surrounds a plasma space containing plasma inside, An extraction plate positioned on the side of the plasma chamber, An antenna assembly disposed within or adjacent to the plasma chamber, An antenna with a loop structure, A dielectric window adjacent to the antenna, and A Faraday shield assembly disposed between the antenna and the dielectric window and at least partially disposed around the antenna, comprising a plurality of metal sections electrically insulated from each other, wherein the plurality of metal sections are arranged in a plurality of shield pairs. An antenna assembly including, An RF assembly connected to the first and second ends of the antenna to provide a balanced RF voltage signal. A processing device equipped with the following features.

18. The apparatus according to claim 17, wherein the RF assembly is configured to supply a first RF signal having a first maximum amplitude and a first phase to the first end, and further configured to supply a second RF signal having a second phase opposite to the first maximum amplitude and the first phase to the second end.

19. The processing apparatus according to claim 17, wherein the RF assembly includes an RF balance network.

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