WO2011041087A2

WO2011041087A2 - Inductively-coupled plasma (icp) resonant source element

Info

Publication number: WO2011041087A2
Application number: PCT/US2010/048573
Authority: WO
Inventors: John M. White; Jonghoon Baek; Tsutomu Tanaka (Tom)
Original assignee: Applied Materials, Inc.
Priority date: 2009-09-29
Filing date: 2010-09-13
Publication date: 2011-04-07
Also published as: WO2011041087A3

Abstract

The present invention generally relates to an inductive-capacitive element that may be used to form a single coil within an inductively-coupled plasma apparatus. One or more elements may be used and coupled together to collectively form the coil. The coil may be coupled to a single match network. Therefore, a single input and a single output may be used for the coil so that fewer penetrations through the chamber walls may be used. The individual inductive-capacitive elements may comprise two overlapping tubes with an insulating material disposed therebetween in an overlapping area. The overlapping area forms a capacitor segment and the non-overlapping area forms an inductor segment. The tubes and insulating material may be welded together to create a resonant circuit with an impedance of zero. Thus, the inductance of the coil is low, only two wall penetrations are utilized and a single match network is utilized.

Description

INDUCTIVELY-COUPLED PLASMA (ICP) RESONANT SOURCE ELEMENT

BACKGROUND OF THE INVENTION

Field of the Invention

[0001] Embodiments of the present invention generally relate to an inductively- coupled plasma (ICP) resonant source element and an apparatus utilizing the ICP element.

Description of the Related Art

[0002] For large area process chambers in which it's desired to use an ICP plasma process, it is necessary to use a single or a few large high-frequency, e.g. , RF, coils to produce electromagnetic fields needed to create plasma within the chamber. The problem in using a large coil is that the voltage required to drive the high inductance of a large coil creates the potential for parasitic capacitive coupling of the coil to the plasma. This in turn leads to a high risk of sputtering the coil material itself. This sputtered material in some applications may be acceptable or at least tolerable, but in cases in which the sputtered material degrades the process or contaminates the film or damages the coil itself, a large coil design is unacceptable.

[0003] As a solution to the situation described above, sources have been developed for large chambers which use several or many smaller coils or coil elements, also called antennae, which by virtue of their shorter length, have smaller inductance and operate at lower voltages. The smaller coils or coil elements solve the problem from which long-length coils suffer. However, the multi-source design requires two vacuum electrical feedthroughs for each element and electrical power matching-network elements with each segment and feedthrough set. This adds considerably to the total cost of these sources as well as adding risk of vacuum leaks at each wall penetrations. As can be easily imagined, it is quite expensive to have a plurality of matching networks and power sources. Additionally, the challenges of tuning multiple matching networks is also burdensome. [0004] Therefore, there is a need in the art for an ICP source that has a low inductance without the need for numerous electrical feedthroughs and power matching-network elements.

SUMMARY OF THE INVENTION

[0005] The present invention generally relates to an inductive-capacitive element that may be used to form a single coil within an ICP apparatus. One or more elements may be used and coupled together to collectively form the coil. The coil may be coupled to a single match network. Therefore, a single input and a single output may be used for the coil so that a minimum amount of penetrations through the chamber walls may be used. The individual inductive-capacitive elements may comprise two overlapping tubes with an insulating material disposed therebetween in an overlapping area. The overlapping area forms a capacitor segment and the non-overlapping area forms an inductor segment. The tubes and insulating material may be welded together to create a resonant circuit with an impedance of zero. Thus, the inductance of the coil is low, only two wall penetrations are utilized and a single match network is utilized.

[0006] In one embodiment, an inductive-capacitive (LC) element is disclosed. The LC element includes a first tube comprising a first conductive material and having an inner diameter. The LC element also includes a second tube comprising a second conductive material and having an outer diameter that is less than the inner diameter. The LC element also includes an insulating material coupled between the first tube and the second tube such that the first tube and the second tube overlap at an overlap area to form a capacitive segment. A portion of the first tube extends a first distance from the capacitive sub-segment in a first direction to form a first inductive segment. A portion of the second tube extends a second distance from the capacitive segment in a second direction opposite the first direction to form a second inductive segment. The insulating material extends a third distance beyond the capacitor segment that is less than the second distance. [0007] In another embodiment, an LC element is disclosed. The LC element includes a first tube comprising a first conductive material and having an inner diameter. The LC element also includes a second tube comprising a second conductive material and having an outer diameter that is less than the first inner diameter. The LC element also includes an insulating material coupled between the first tube and the second tube such that the first tube and the second tube overlap at an overlap area. The first tube and the second tube are spaced apart by a gap for a portion of the overlap area such that the overlap area forms a capacitive segment. A portion of the first tube extends a first distance from the overlap area in a first direction to form a first inductive segment. A portion of the second tube extends a second distance from the overlap area in a second direction opposite the first direction to form a second inductive segment.

[0008] In another embodiment, coil for use in an inductively coupled plasma source is disclosed. The coil includes a plurality of LC elements coupled together. Each LC element comprises a first tube comprising a first conductive material and having a first outer diameter and a first inner diameter greater than the first outer diameter. Each LC element also includes a second tube comprising a second conductive material and having a second outer diameter that is less than the first inner diameter and substantially equal to the first outer diameter. The second tube also has a second inner diameter substantially equal to the first inner diameter. The LC element also includes a insulating material coupled between the first tube and the second tube such that the first tube and the second tub overlap at an overlap area to form a capacitive segment. The first tube extends a first distance from the capacitive segment in a first direction to form a first inductive segment. The second tube extends a second distance from the capacitive segment in a second direction opposite the first direction to form a second inductive segment. The insulating material extends a third distance beyond the capacitive segment that is less than the second distance. The plurality inductive-capacitive elements are coupled together by coupling adjacent inductive segments to capacitive segments. [0009] In another embodiment, coil for use in an inductively coupled plasma source is disclosed. The coil includes a plurality of LC elements coupled together. Each LC element includes a first tube comprising a first conductive material and having a outer diameter and a first inner diameter greater than the first outer diameter. Each LC element also includes a second tube comprising a second conductive material and having a second outer diameter that is less than the first inner diameter and substantially equal to the first outer diameter. The second tube also has a second inner diameter substantially equal to the first inner diameter. Each LC element also includes an insulating material coupled between the first tube and the second tube such that the first tube and the second tube overlap at an overlap area. The first tube and the second tube are spaced apart by a gap for a portion of the overlap area and the first tube extends a first distance from the overlap area in a first direction. The second tube extends a second distance from the overlap area in a second direction opposite the first direction. The plurality of inductive-capacitive elements are coupled together by coupling first tubes to adjacent second tubes at an overlap area having insulating material and a gap.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

[0011] Figure 1 is a schematic cross-sectional view of an ICP apparatus according to one embodiment.

[0012] Figure 2A is a schematic isometric view of an inductive-capacitive element according to one embodiment. [0013] Figure 2B is a schematic cross-sectional view of the inductive-capacitive element of Figure 2A.

[0014] Figure 3A is a schematic isometric view of an inductive-capacitive element according to one embodiment.

[0015] Figure 3B is a schematic cross-sectional view of the inductive-capacitive element of Figure 3A.

[0016] Figure 4A is a schematic isometric view of an inductive-capacitive element according to another embodiment.

[0017] Figure 4B is a schematic cross-sectional view of the inductive-capacitive element of Figure 4A.

[0018] Figure 5 is a schematic top view of an ICP apparatus with the cover removed to show a coil arrangement according to another embodiment.

[0019] Figure 6 is a schematic top view of an ICP apparatus with the cover removed to show a coil arrangement according to another embodiment.

[0020] Figure 7A is a schematic top view of an ICP apparatus with the cover removed to show a coil arrangement according to another embodiment.

[0021] Figure 7B is a schematic cross sectional view of the ICP apparatus of Figure 7A.

[0022] Figure 8 is a schematic top view of an ICP apparatus with the cover removed to show a coil arrangement according to another embodiment.

[0023] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation. DETAILED DESCRIPTION

[0024] The present invention generally relates to an inductive-capacitive element that may be used to form a single coil within an ICP apparatus. One or more elements may be used and coupled together to collectively form the coil. The coil may be coupled to a single match network. Therefore, a single input and a single output may be used for the coil so that a minimum amount of penetrations through the chamber walls may be used. The individual inductive-capacitive elements may comprise two overlapping tubes with an insulating material disposed therebetween in an overlapping area. The overlapping area forms a capacitor segment and the non-overlapping area forms an inductor segment. The tubes and insulating material may be welded together to create a resonant circuit with an impedance of zero. Thus, the inductance of the coil is low, only two wall penetrations are utilized and a single match network is utilized.

[0025] The embodiments discussed herein may be utilized in an ICP chamber manufactured by AKT America, Inc., a subsidiary of Applied Materials, Inc., Santa Clara, California. It is to be understood that the embodiments discussed herein may be utilized in other chambers as well, including chambers sold by other manufacturers.

[0026] Figure 1 is a schematic cross-sectional view of an ICP apparatus according to one embodiment. The apparatus includes a chamber 100 having a plurality of walls 102. At least one wall 102 has a slit valve opening 106 therethrough to permit a substrate 110 to enter and exit the chamber 100. The chamber 100 has a lid 104 coupled to the chamber walls 102 with an o-ring 136 therebetween to ensure a vacuum may be maintained within the chamber 100. the chamber 100 may be evacuated by a vacuum pump 128.

[0027] The substrate 110 may be placed onto lift pins 114 when entering the chamber 100. In one embodiment, the lift pins 114 may be coupled to a lift plate

112. The lift plate 112 may be disposed on a stem 122 that is raised and lowered by an actuator 126. A bellows 124 may be used to isolate the stem 122 and actuator

126 from vacuum. In another embodiment, the lift pins 114 may simply suspend from the susceptor 108 and remain stationary relative to the moving susceptor 108. The susceptor 108 may be coupled to a stem 116 that is raised and lowered by an actuator 120. The actuator 120 and stem 116 may be isolated from the vacuum environment by a bellows 118.

[0028] The gas for processing the substrate 110 or cleaning the chamber 100 may be introduced through inlets 134 into the chamber 100 from a gas source 130 or remote plasma source through tubes 132. During a deposition process, the gas is introduced from the gas source 130 through the inlets 134 where the gas is dissociated into a plasma for deposition onto the substrate 1 0. The gas may be introduced into the chamber from any location. In the embodiment shown in Figure 1 , the inlets 134 are disposed through the lid 104 and the chamber walls 102. However, the inlets 134 are not so limited. The inlets 134 may be disposed at any location through the chamber that is practical for the layout of the chamber components. Because the gas disperses within the chamber wall, the location of the inlets 134 may be chosen to suit the needs of the user.

[0029] The gas is dissociated by the coil 144 within the chamber 100. In one embodiment, the coil 144 may be hollow and coupled to a cooling fluid source 142 to permit a cooling fluid to flow therethrough. Current is applied to the coil 144 from a power source 138 through a matching network 140. The current moves back and forth and a magnetic field is generated around the coil 144 which creates the electric field that dissociates the gas.

[0030] The coil 144 may be spaced from the substrate 1 10 by a distance represented by arrow "B". The coil 144 may be a multi-turn coil with adjacent parallel portions spaced apart by a distance represented by arrow "A". In one embodiment, the ratio of "A" to "B" is about 1 :1. The closer that the parallel portions of the coil 144 are to each other, the better the plasma uniformity. However, in order to have more parallel portions of the coil 144, more materials are utilized which may increase the cost. As needed, the various portions of the coil 144 may be spaced different distances from the substrate 110 to change the plasma distribution with the chamber 100. [0031] One embodiment contemplated herein involves the construction of an inductive-capacitive (LC) element and a resonant or near-resonant coil segment. The LC element disclosed herein has many benefits. One benefit is the LC element is designed to be low-cost to manufacture. Another benefit is the LC element efficiently conducts high electrical (e.g., RF) currents. Additionally, the LC element is able to be exposed in a vacuum chamber that employs aggressive plasma chemistries such as those used in the manufacturing of semiconductors, thin-film solar and flat panel displays. Finally, the LC element is temperature-controlled (i.e., cooled).

[0032] The ICP chamber has advantages over a parallel plate type PECVD chamber in that the gas may be introduced from generally any location into the chamber because the gas will disperse well. Additionally, the susceptor can be stationary because a large distance, such as between about 10 cm to about 15 cm, may be between the susceptor and the coil. The large distance between the susceptor and coil permits the substrate to be introduced into the chamber without fear of colliding into the coil or susceptor due to misalignment. Thus, particles generated may be less as compared to a parallel plate reactor. Additionally, because the susceptor may be stationary, the RF return path may be easy to construct and predict should any capacitive coupling occur. In general, the ICP chamber may be operated at a chamber pressure of between about 5 mTorr to about 20 mTorr. In one embodiment, the chamber pressure may be between about 10 mTorr to about 15 mTorr.

[0033] Figure 2A is a schematic isometric view of an inductive-capacitive element 200 according to one embodiment. Figure 2B is a schematic cross-sectional view of the inductive-capacitive element 200 of Figure 2A. The inductive-capacitive element 200 includes a first tube 202, a second tube 204, and an insulator 206 coupled therebetween. In one embodiment, the first tube 202 and the second tube 204 may each comprise a conductive material. In another embodiment, the first tube 202 and the second tube 204 may comprise a material selected from the group consisting of aluminum and aluminum alloys. In one embodiment, the insulator 206 may comprise an insulating material. In another embodiment, the insulator 206 may comprise a material selected from the group consisting of aluminum oxide, aluminum nitride and combinations thereof.

[0034] When the first tube 202, the second tube 204 and the insulator 206 are assembled together, they create a first portion or first inductor segment 208, a second portion or second inductor segment 212 and a third portion or capacitive segment 210. Cooling fluid may flow along a cooling flow path 216 from one end 218 to another end 218 of the assembled inductive-capacitive element 200. In order to keep the cooling flow path 216 isolated from the vacuum environment, vacuum tight joints 214 should be present between the first tube 202, the insulator 206 and the second tube 204. The joints 214 may be formed by welding the pieces together. In one embodiment, the pieces are spin welded together.

[0035] The pieces are welded together such that the capacitor segment 210 is formed. Both the first tube 202 and the second tube 204 have an outer diameter shown by arrow "C" that is less than an inner diameter "D". As shown in Figure 2A, each tube has a smaller diameter portion and a larger diameter portion. To weld the pieces together, the smaller diameter portion of one tube is inserted into the larger diameter portion of the other tube with insulating material coupled between the overlapping tube portions. In one embodiment, the inside diameter may be between about 0.75 inches and about 1.25 inches. The insulator 206 is fitted between the first tube 202 and the second tube 204. The insulator 206 extends for a distance beyond the second tube 204 along the inside of the second tube 204. Additionally, the insulator 206 extends for a distance beyond the first tube 202 over the outside surface of the first tube 202.

[0036] The capacitive segment 210 functions as a capacitor so that current may travel from the first tube 202 to the second tube 204 with an impedance of zero. A plurality of inductive-capacitive elements may be strung together to form a coil. The tubes of adjacent inductive-capacitive elements may be welded together end to end or interspersed with additional lengths of conductive tubing to provide the appropriate segment inductance for resonance. [0037] The inductive-capacitive element 200 has the insulator 206 extending a predetermine distance beyond the capacitor segment 210. Thus, if used in a deposition chamber, the insulator 206 may be exposed to deposition material. If the deposition material is an insulating material, any material that bridges from the first tube 202 to the second tube 204 over the insulator 206 has no negative effect because the deposition material is insulating. However, if the deposition material is conductive, material that bridges from the first tube 202 to the second tube 204 could cause a shorting of the inductive-capacitive element 200.

[0038] Figures 3A and 3B show a variation on the design of the LC element described above in reference to Figures 2A and 2B. For the purpose of depositing non-insulating (conducting or semiconducting) films in such an ICP process chamber, it would be necessary to provide protection of the plasma/vacuum- exposed surface of the capacitor/dielectric sub-segment of the LC element. If such protection is not provided, the capacitor sub-segment would become shorted and fail to function in the LC element. By "shadowing" the (outer) vacuum-exposed surface of the dielectric material from non-insulating deposition, the LC element can continue to operate properly for a sufficient period of time. The vacuum gap, which would unavoidably be created by shadowing the dielectric, would have to be sized/designed so as to make it resistant to arcing between the inner conductor tube and the outer conductor tube. If the gap is made appropriately small, it can have a sufficiently high breakdown voltage.

[0039] Figure 3A is a schematic isometric view of an inductive-capacitive element 300 according to one embodiment. Figure 3B is a schematic cross-sectional view of the inductive-capacitive element 300 of Figure 3A. Cooling fluid may flow along the cooling flow path 320 from end 322 to end 322 of the inductive-capacitive element 300. The insulating material 314 is shown to not extend into the inductor element 308 beyond the capacitor sub-segment 310 within the first tube 302, however, in one embodiment, the insulating material 314 may extend into the inductor segment 308. Similarly, the insulating material 314 does not extend out over the second tube 304 beyond the capacitor segment 310 onto the inductive segment 312. The insulating material 314 is welded to the first tube 302 and the second tube 304 in a manner as discussed above to form vacuum tight joints 316 such that the cooling flow path 320 is isolated from the vacuum environment.

[0040] In the embodiment shown in Figures 3A and 3B, the insulating material 314 does not extend for the entire length of the capacitor segment 310 and does not extend beyond the capacitor segment 310 over the second tube 304. Rather, a portion of the capacitor segment 310 includes a gap 306 between the first tube 302 and the second tube 304. The gap 306 is large enough such that no bridging of material from the first tube 302 to the second tube 304 would be expected to occur prior to routine cleaning. For example, when depositing micro-crystalline silicon, microcrystalline silicon would be expected to deposit over a portion of the first tube 302 as well as the second tube 304. However, the amount of material that is deposited would likely not bridge the gap 306. During normal operation, the chamber would be periodically cleaned. The cleaning gas, such as NF₃ in the case of cleaning microcrystalline silicon, would sufficiently disperse to clean any microcrystalline silicon that has deposited within the gap 306.

[0041] Figure 4A is a schematic isometric view of an inductive-capacitive element according to another embodiment. Figure 4B is a schematic cross-sectional view of the inductive-capacitive element of Figure 4A. In the embodiments shown in Figures 4A and 4B, the inductive-capacitive element 400 includes a first tube 402, second tube 404, and insulating material 414. Cooling fluid may flow along the cooling flow path 420 from end 422 to end 422 of the inductive-capacitive element 400. The insulating material 414 extends into the first tube 402 and is overlapped by both the first tube 402 and second tube 404 as a capacitor segment 410. The insulating material 414 extends into the inductor segment 408 of the first tube 402 for a distance beyond the second tube 404. Similarly, the insulating material 414 may extend out over the second tube 404 beyond the capacitor segment 410 into the inductive segment 412. The insulating material 414 is welded to the first tube 402 and the second tube 404 in a manner as discussed above to form vacuum tight joints 416 such that the cooling flow path 420 is isolated from the vacuum environment. Additionally, the portion of the insulating material 414 that extends over the second tube 404 may be spaced from the second tube 404 by a gap 406 which is an anti-arcing/shorting gap 406 to prevent arcing from the first tube 402 to the second tube 404.

[0042] In another embodiment, the inductive-capacitive elements discussed above may be constructed into a complete induction "coil". The LC element segments would be assembled, preferably welded, end to end to create a coil of desired impedance characteristics and length to sufficiently uniformly fill the large- area processing chamber with plasma. The shape or "path" of the coil inside the process chamber can be modified/adjusted to optimize the on-substrate process uniformity, gas utilization efficiency, power utilization efficiency, etc. Because the LC element segments are very low impedance at or near resonance at the driving frequency, the number of elements in series and thus the total length of the coil can be arbitrarily long; and yet the maximum voltage of the coil with respect to the plasma at all locations on the coil will remain low. Based upon practical sizes of the elements for ease of fabrication, low megahertz (e.g., 2MHz) excitation frequency is a most desirable frequency to use for ICP and is well known to produce IC plasma that is useful for semiconductor, solar and flat panel display processing applications.

[0043] Figure 5 is a schematic top view of an ICP apparatus with the cover removed to show a coil arrangement according to one embodiment. The apparatus includes a chamber 500 in which a single turn ICP coil 502 is coupled to a matching network 504 after penetrating through the vacuum penetration 508 through the chamber walls. The matching network 504 may be coupled to an excitation power source 506. As shown in Figure 5, the ICP coil 502 is disposed above the substrate 510, but is disposed around the perimeter of the substrate 510. The coil 502 comprises a plurality of LC elements 512 and conductors 514. In the embodiment shown in Figure 5, there are four LC element segments connected in series. The length of the conductor 514 may be selected to produce the overall LC desired for resonance in the segment. While the coil 502 has been described as being over the substrate 510, it is to be understood that the orientation may be changed such that the chamber 500 is rotated 90 degrees such that the coil 502 is simply across a processing space from the substrate 510. Similarly, the chamber 500 may be rotated 180 degrees so that the substrate 510 is above the coil 502.

[0044] Figure 6 is a schematic top view of an ICP apparatus with the cover removed to show a coil arrangement according to another embodiment. The chamber 600 includes a coil 602 disposed above the substrate 610 and encircling the processing space. The coil 602 is coupled to the matching network 604 and the power source 606 through vacuum penetrations 608. In the embodiment shown in Figure 6, there are eight LC element segments connected in series.

[0045] The coil shown in Figures 5 and 6 may be beneficial over a single turn coil without any LC elements because a single coil would require a significant amount of voltage relative to the coils shown in Figures 5 and 6 in order to provide the same plasma density. However, the single coil would run the risk of sputtering as discussed above and have a high inductance. Utilizing a plurality of LC elements coupled together to form a coil, the coils of Figures 5 and 6 have a much lower inductance due to the capacitor sub-segments. In fact, the inductance may be chosen to suit the needs of the user. The length of the inductance sub-segments may be chosen to achieve the desired resonance for the LC segments.

[0046] For the single coil systems that did not have LC segments, the coils had a practical limit in terms of length. The greater the length, the larger the inductance and the larger the voltage necessary to produce the desired plasma. With the larger voltage, the greater the likelihood of sputtering. Therefore, a tradeoff would be necessary. If no sputtering is permitted, the coil length could only be so long. Thus, the size of the chamber would be limited by the inductance of the coil. If the coil length was too long, then it would have to be accepted that sputtering would occur which could contaminate the substrate. The coils discussed herein that have LC elements, however, could be as long as desired without any undesired sputtering effects. In other words, the coils discussed herein that have LC elements do not simply have to be confined to the perimeter of the substrate, but rather, the coils discussed herein that have LC elements could have multiple turns and cross the processing space multiple times.

[0047] Figure 7A is a schematic top view of an ICP apparatus with the cover removed to show a coil arrangement according to another embodiment. The chamber 700 includes a coil 702 that is arranged in a serpentine configuration. The coil 702 is coupled to a matching network 704 and power source 706 through the vacuum penetrations 708. The coil 702 is disposed above the substrate 710. The shape and design of the coil 702 can be varied above the substrate 710 such that the distance between adjacent sections of the coil 702 can be different. For example, the distance shown by arrow Έ" is less than the distance shown by arrow "F", and the distance shown by arrow "F" is less than the distance shown by arrow "G". Between the center and the edge of the substrate, the coil 702 may be formed to have a variation in distance from the plane of the substrate to achieve a desired plasma or process uniformity in the chamber 700. In the embodiment shown in Figure 7A, there are 16 LC elements.

[0048] By adjusting the spacing between adjacent portions of the coil 702, the plasma density may be adjusted. For example, if the deposition at the edge of the substrate 710 is less than the center, then having the portions of the coil 702 closer together may increase the plasma density near the edge of the substrate 710. Similarly, the spacing between adjacent portions of the coil 702 may be increased near the center of the substrate 710 such that the plasma density is reduced near the center area of the substrate 710. Additionally, the spacing between the coil 702 and the substrate 710 may be adjusted. For example, portions of the coil 702 may be spaced a first distance from the substrate 710 while other portions of the coil 702 may be spaced a second distance from the substrate 710 that is less than the first distance. Thus, the coil 702 layout may be tailored to achieve the desired results by reasonable experimentation. Figure 7B is a schematic cross sectional view of the ICP apparatus of Figure 7A. As shown in Figure 7B, the coil 702 may be spaced from the chamber cover by a distance shown by arrows "M". Figure 7B also shows the vacuum penetrations 708. [0049] Figure 8 is a schematic top view of an ICP apparatus with the cover removed to show a coil arrangement according to another embodiment. The chamber 800 includes a coil 802 that is arranged in a spiral configuration. The coil 802 is coupled to a matching network 804 and power source 806 through the vacuum penetrations 808. The coil 808 is disposed above the substrate 810. The shape and design of the coil 802 can be varied above the substrate 810 such that the distance between adjacent sections of the coil 802 can be different. For example, the distance shown by arrow "H" is less than the distance shown by arrow "J", and the distance shown by arrow "J" is less than the distance shown by arrow "K". Between the center and the edge of the substrate, the coil 802 may be formed to have a variation in distance from the plane of the substrate to achieve a desired plasma or process uniformity in the chamber 800. In the embodiment shown in Figure 8, there are 19 LC elements.

[0050] As an example of the benefits of utilizing LC elements to form a coil, consider the example of a processing chamber having a chamber volume of about 550,000 cm³, a coil resistance of 5 Ohm and a loop inductance of 8.37 ocH. The load impedance with plasma at 2MHz is 5+105i with the assumption that reactance does not change much with plasma. At 10kW, the current is 44.7 A_ms and the maximum voltage for an unsegmented coil is 4711 Vrm_S, a 4-segmentted coil is 1 175 Vrms, an 8-segmented coil is 588 V_rms, a 16-segmented coil is 294 V_rms and a 32 segmented coil is 147 V_rms. Thus, the more LC elements used (and hence, the more segments), the lower the voltage.

[0051] In order to design the optimum coil for deposition purposes in an ICP chamber using one or more LC elements, the technician needs to determine the size of the chamber into which the coil will be placed. Then, the technician will need to determine how many turns in the coil will be necessary to achieve the desired plasma distribution. The frequency applied may be between about 1 MHz to about 13 MHz during operation. Once the number of turns, and hence the length, has been determined, the number of LC elements to be used is determined. Each segment is then welded together to daisy-chain the pieces together to form one large coil. Each segment has zero impedance. Therefore, the whole coil is a resonant coil. If the various pieces are not joined to form identical pieces between the LC elements, there will be a different voltage across the coil because the voltage will drop. If there is perfect joining of the pieces, then there will theoretically be no voltage drop along the coil.

[0052] There are numerous advantages to utilizing the LC elements described herein. For example, by utilizing a plurality of LC elements coupled together, a coil may be fabricated with multiple turns. The coil would have a sufficiently low voltage and inductance that the amount of sputtering from the coil could be minimal. Because the coil can have multiple turns, large area processing chamber scan be fabricated without any fear of sputtering the coil. Thus, ICP chambers could rival parallel plate chambers in terms of device performance while potentially having a simpler design. The coil may be coupled to a single matching network and have two vacuum penetrations. The coil may be designed to obtain the desired deposition characteristics. By coupling the LC elements together, fewer vacuum penetrations would be needed, fewer matching networks would be needed, and large area ICP chambers are possible.

[0053] While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

Claims:

1. An inductive-capacitive element, comprising:

a first tube comprising a first conductive material, the first tube having an inner diameter;

a second tube comprising a second conductive material and having an outer diameter that is less than the inner diameter; and

an insulating material coupled between the first tube and the second tube such that the first tube and the second tube overlap at an overlap area to form a capacitive segment, a portion of the first tube extends a first distance from the capacitive segment in a first direction to form a first inductive segment and a portion of the second tube extends a second distance from the capacitive segment in a second direction opposite the first direction to form a second inductive segment, the insulating material extending a third distance beyond the capacitor segment that is less than the second distance.

2. The inductive-capacitive element of claim 1 , wherein the first tube and the insulating material are coupled together to form a vacuum tight joint, wherein the second tube and the insulating material are coupled together to form a vacuum tight joint, and wherein the first tube and the second tube are hollow such that the inductive-capacitive element has a passage therein to permit a cooling fluid to pass therethrough.

3. The inductive-capacitive element of claim 1 , wherein the first conductive material and the second conductive material each are selected from the group consisting of aluminum and aluminum alloys and wherein the insulating material is selected from the group consisting of aluminum nitride, aluminum oxide and combinations thereof.

4. The inductive-capacitive element of claim 1 , wherein the inductive-capacitive element is spin-welded together.

5. An inductive-capacitive element, comprising:

a first tube comprising a first conductive material and having an inner diameter;

an insulating material coupled between the first tube and the second tube such that the first tube and the second tube overlap at an overlap area, the first tube and the second tube are spaced apart by a gap for a portion of the overlap area such that the overlap area forms a capacitive segment, a portion of the first tube extends a first distance from the overlap area in a first direction to form a first inductive segment and a portion of the second tube extends a second distance from the overlap area in a second direction opposite the first direction to form a second inductive segment.

6. The inductive-capacitive element of claim 5, wherein the first tube and the insulating material are coupled together to form a vacuum tight joint, wherein the second tube and the insulating material are coupled together to form a vacuum tight joint, and wherein the first tube and the second tube are hollow such that the inductive-capacitive element has a passage therein to permit a cooling fluid to pass therethrough.

7. The inductive-capacitive element of claim 5, wherein the first conductive material and the second conductive material each are selected from the group consisting of aluminum and aluminum alloys, wherein the insulating material is selected from the group consisting of aluminum nitride, aluminum oxide and combinations thereof, and wherein the inductive-capacitive element is spin-welded together.

8. A coil for use in an inductively coupled plasma source, comprising:

a plurality of inductive-capacitive elements coupled together, each inductive- capacitive element comprising: a first tube comprising a first conductive material and having a first outer diameter and a first inner diameter greater than the first outer diameter;

a second tube comprising a second conductive material and having a second outer diameter that is less than the first inner diameter and substantially equal to the first outer diameter, the second tube also having a second inner diameter substantially equal to the first inner diameter; and

a insulating material coupled between the first tube and the second tube such that the first tube and the second tub overlap at an overlap area to form a capacitive segment, the first tube extends a first distance from the capacitive segment in a first direction to form a first inductive segment, and the second tube extends a second distance from the capacitive segment in a second direction opposite the first direction to form a second inductive segment, the insulating material extends a third distance beyond the capacitive segment that is less than the second distance, the plurality inductive-capacitive elements are coupled together by coupling adjacent inductive segments to capacitive segments.

9. The coil of claim 8, wherein the plurality of inductive-capacitive elements comprises at least four inductive-capacitive elements and wherein the coil has multiple turns.

10. The coil of claim 8, wherein the first tube and the insulating material are coupled together to form a vacuum tight joint, wherein the second tube and the insulating material are coupled together to form a vacuum tight joint, and wherein the first tube and the second tube are hollow such that the inductive-capacitive element has a passage therein to permit a cooling fluid to pass therethrough.

11. The coil of claim 8, wherein the first conductive material and the second conductive material each are selected from the group consisting of aluminum and aluminum alloys, wherein the insulating material is selected from the group consisting of aluminum nitride, aluminum oxide and combinations thereof, and wherein the inductive-capacitive element is spin-welded together.

12. A coil for use in an inductively coupled plasma source, comprising:

a plurality of inductive-capacitive elements coupled together, each inductive- capacitive element comprising:

a first tube comprising a first conductive material and having an outer diameter and a first inner diameter greater than the first outer diameter;

an insulating material coupled between the first tube and the second tube such that the first tube and the second tube overlap at an overlap area, the first tube and the second tube are spaced apart by a gap for a portion of the overlap area and the first tube extends a first distance from the overlap area in a first direction and the second tube extends a second distance from the overlap area in a second direction opposite the first direction, the plurality of inductive-capacitive elements are coupled together by coupling first tubes to adjacent second tubes at an overlap area having insulating material and a gap.

13. The coil of claim 12, wherein the plurality of inductive-capacitive elements comprises at least four inductive-capacitive elements and wherein the coil has multiple turns.

14. The coil of claim 12, wherein the first tube and the insulating material are coupled together to form a vacuum tight joint, wherein the second tube and the insulating material are coupled together to form a vacuum tight joint, and wherein the first tube and the second tube are hollow such that the inductive-capacitive element has a passage therein to permit a cooling fluid to pass therethrough.

15. The coil of claim 12, wherein the first conductive material and the second conductive material each are selected from the group consisting of aluminum and aluminum alloys, wherein the insulating material is selected from the group consisting of aluminum nitride, aluminum oxide and combinations thereof, and wherein the inductive-capacitive element is spin-welded together.