Remote surface wave propagation in semiconductor chambers.

Abstract

An apparatus for providing a plasma in a process volume of a chamber, the apparatus comprising: a plurality of plasma sources, each having at least a dielectric tube inlet at least partially surrounded by a conductive tube configured to be connected to RF power to generate a plasma, and a gas inlet disposed opposite the dielectric tube inlet, and a dielectric tube directly connected to each of the plurality of plasma sources, the dielectric tube configured to at least partially contain the plasma generated by the plurality of plasma sources and configured to emit radicals generated in the plasma through holes or nozzles in the dielectric tube.

Description

[Technical field]

[0001] FIELD OF THE PREFERRED EMBODIMENTS

[0001] Embodiments of the present principles relate generally to semiconductor processing of semiconductor substrates. [Background technology]

[0002]

[0002] Semiconductor processing may require plasma generation for deposition, oxidation, etching, and other processes. The plasma may be generated directly inside the processing space of the chamber, or may be generated remotely from the chamber and the resulting radicals etc. may be induced into the chamber. Conventional remote plasma sources require an ignition sequence and then appropriate conditions to maintain the plasma each time it is needed in the process. The inventors have observed that this process may affect the process yield due to a delay in igniting the plasma to generate the required output such as radicals. The inventors have also observed that the cycling of the plasma affects the efficiency of the process, requiring a large power each time to ignite the plasma.

[0003]

[0003] Accordingly, the present inventors have provided a method and apparatus that provides an efficient and consistent remote plasma source that produces higher radical densities. Summary of the Invention

[0004] Provided herein are methods and apparatus for a remote plasma source with high efficiency and enhanced process uniformity on a substrate.

[0005] In some embodiments, an apparatus having a plasma source may include a chamber having a bottom, a lid, and a wall providing a process space above a substrate support, and multiple plasma sources directly interconnected via a dielectric tube, the dielectric tube extending at least partially into the process space, the multiple plasma sources configured to generate surface waves at the walls of the dielectric tube supporting plasma generation within the dielectric tube.

[0006]

[0006] In some embodiments, the apparatus may further include: the plurality of plasma sources are disposed within a wall of the chamber and partitioned off from the processing space; one or more of the plurality of plasma sources have one or more gas inlets configured to provide a process gas or reactive gas to the interior of the dielectric tube; at least one of the one or more gas inlets is disposed at an opposite end of one or more of the plurality of plasma sources from an end at which the dielectric tube extends from the end of one or more of the plurality of plasma sources; the dielectric tube has one or more gas inlets configured to provide a process gas or reactive gas to the interior of the dielectric tube; the dielectric tube has a plurality of holes or nozzles directed toward the substrate support; the plurality of holes or nozzles configured to emit radicals from within the dielectric tube toward the substrate support; the dielectric tube has a generally circular shape that mimics the periphery of the processing space; the dielectric tube has a concentric circular portion and a radially extending portion that connects to the concentric circular portion; the dielectric tube has an outer diameter less than about 0.5 inches and an inner diameter less than about 0.3 inches; the chamber is an etch chamber or a deposition chamber. At least one of the multiple plasma sources is a surfatron having a length and width less than 3 inches; the multiple plasma sources are disposed externally around the walls of the chamber; the multiple plasma sources are disposed above and externally relative to a lid of the chamber; and / or each of the multiple plasma sources is connected to at least one RF power source. The at least one RF power source provides RF power to a circular conductive tube that surrounds a portion of the dielectric tube.

[0007]

[0007] In some embodiments, an apparatus for providing plasma to a chamber may include a plurality of plasma sources. Each plasma source has at least a dielectric tube inlet. The dielectric tube inlet is at least partially surrounded by a conductive tube. The conductive tube is configured to be connected to RF power to generate the plasma. Each plasma source further has at least a gas inlet disposed opposite the dielectric tube inlet. The apparatus may further include a dielectric tube directly connected to each of the plurality of plasma sources. The dielectric tube is configured to at least partially contain the plasma generated by the plurality of plasma sources and configured to emit radicals generated in the plasma through a hole or nozzle in the dielectric tube. The hole or nozzle in the dielectric tube is disposed within a portion of the dielectric tube configured to be inserted into the chamber.

[0008]

[0008] In some embodiments, the apparatus may further include: the dielectric tube has a circular shape that mimics the outer periphery of the interior space of the chamber; the dielectric tube has a radially extending portion that connects to the concentric circular portion; the dielectric tube has an outer diameter less than about 0.5 inches and an inner diameter less than about 0.3 inches; and / or at least one of the multiple plasma sources is a surfatron having a length and width less than 3 inches.

[0009]

[0009] In some embodiments, the apparatus having a plasma source may include a chamber having a bottom, a lid, and walls providing a process space above the substrate support. The apparatus may further include a plurality of plasma sources having an inlet and an outlet through which a dielectric tube passes. The plurality of plasma sources are disposed within the walls of the chamber and are screened from direct exposure to the process space. Each of the plurality of plasma sources is a surfatron having a length, width, and height of less than 3 inches. The apparatus may further include a dielectric tube. The dielectric tube is directly connected to each of the plurality of plasma sources. The dielectric tube extends at least partially into the process space. The dielectric tube has one or more gas inlets for gases that generate plasma within the dielectric tube.

[0010]

[0010] Other further embodiments are described below.

[0011]

[0011] The embodiments of the present principles, briefly summarized above and described in detail below, may be understood by reference to exemplary embodiments of the present principles as illustrated in the accompanying drawings. However, since the present principles may admit of other equally effective embodiments, the accompanying drawings illustrate only typical embodiments of the present principles and therefore should not be considered as limiting the scope. [Brief description of the drawings]

[0012] [Figure 1]

[0012] A cross-sectional view of a Surfatron assembly having a pass-through according to some embodiments of the present principles is shown. [Diagram 2]

[0013] FIG. 1 shows a top view of a plasma source having multiple surfatron assemblies, in accordance with some embodiments of the present principles. [Diagram 3]

[0014] 1 shows a cross-sectional view of a dielectric tube hole / nozzle direction relative to a substrate support surface, according to some embodiments of the present principles. [Figure 4]

[0015] FIG. 13 shows a top view of a nozzle extension for an externally mounted dielectric tube, according to some embodiments of the present principles. [Diagram 5]

[0016] 1 shows a top view of an internally mounted dielectric tube according to some embodiments of the present principles. [Figure 6]

[0017] 13A-13C are top views of further circular sections of dielectric tubes, in accordance with some embodiments of the present principles. [Figure 7]

[0018] 1 shows a cross-sectional view of a Surfatron assembly without a pass-through, in accordance with some embodiments of the present principles. [Figure 8]

[0019] 1 shows a cross-sectional view of a Surfatron assembly without a pass-through, in accordance with some embodiments of the present principles. [Figure 9]

[0020] 1 shows a cross-sectional view of a Surfatron assembly with a UV filter according to some embodiments of the present principles. [Figure 10]

[0021] 1 shows a cross-sectional view of a process chamber having a single top-mounted plasma source in accordance with some embodiments of the present principles. [Figure 11]

[0022] 1 shows a cross-sectional view of a process chamber having two top-mounted plasma sources in accordance with some embodiments of the present principles. [Figure 12]

[0023] 1 shows a cross-sectional view of a process chamber having two side mounted plasma sources in accordance with some embodiments of the present principles. [Figure 13]

[0024] 1 shows a cross-sectional view of a process chamber having two side-mounted plasma sources directly connected to a dielectric tube in accordance with some embodiments of the present principles. [Figure 14]

[0025] FIG. 1 shows a cross-sectional view of a process chamber with two top-mounted plasma sources directly connected to a dielectric tube, according to some embodiments of the present principles. [Figure 15]

[0026] 1 shows an isometric view of an alternative dielectric tube configuration, in accordance with some embodiments of the present principles. [Figure 16]

[0027] FIG. 1 shows a top view of a dielectric tube lattice configuration powered by multiple RF generators, in accordance with some embodiments of the present principles. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013]

[0028] For ease of understanding, the same reference numbers have been used, where possible, to designate identical elements common to the figures. The figures are not to scale and may be simplified for clarity. Elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

[0014]

[0029] The method and apparatus provide a new type of remote plasma source for semiconductor chambers based on surface wave propagation along a dielectric surface, which can operate at a wide range of frequencies from megahertz to gigahertz. The plasma source is a miniaturized remote plasma source with high plasma density and high radical delivery efficiency. The small size of the remote plasma source is on the order of a few inches, which can be easily located, especially when retrofitting or providing additional remote plasma sources to an existing chamber design. High plasma density can be achieved in the VHF to UHF frequency range, and the plasma density can be approximately 10 11 cm -3 From 10 12 cm -3 In addition, high radical delivery efficiency is obtained, where the RF power is precisely placed in the plasma along the dielectric surface so that radicals can be generated near the target surface as the dielectric part extends into the process chamber.

[0015]

[0030] Remote plasma sources are conventionally used in the semiconductor industry for such purposes as drying and removing photoresist or chamber cleaning for chemical vapor deposition (CVD) and / or plasma-enhanced vapor deposition (PVD) processes. The remote plasma dissociates source gases and then the radicals are flowed into the process chamber for further reaction. Depending on the process requirements, charged particles or ultraviolet (UV) radiation from the plasma source can be blocked to prevent UV damage to the chamber or the wafer being processed. Conventional remote plasma sources, transformer-coupled toroidal sources, microwave sources, inductively coupled sources, or capacitively coupled sources are all manufactured and commercially available, but do not offer the efficiency and uniformity control provided by the method and apparatus of the present principles.

[0016]

[0031] The miniaturized surfatron of the present principles can be utilized in conjunction with a dielectric tube to spread the plasma into a process chamber while maintaining the plasma within the dielectric tube. The inventors have discovered that the dielectric tube acts as a reduced pressure boundary inside the processing volume of the process chamber, allowing plasma reactions and radical supply at very low pressures, at least down to 0.01 mTorr. Maintaining the plasma and radical supply at such low pressures was unexpected by the inventors. The inventors have discovered that at low pressures, electrons flow in large volumes parallel to the walls of the dielectric tube, dramatically reducing collisions (as opposed to electrons moving perpendicular to the walls of the dielectric tube). The inventors believe that the increased collision distance allows the plasma to be maintained at much lower pressure levels than conventional plasma sources that generate vertical electric fields. The inventors also believe that the surfatron of the present principles acts as a coaxial line, where the center rod is the plasma and the ground is the housing of the surfatron. The low pressure plasma is maintained by the plasma being intimately coupled to the ground, with uninterrupted wave propagation between them. As a result, the efficiency of the Surfatron based on this principle can be five to ten times higher than that of conventional remote plasma sources.

[0017]

[0032] The inventors have also discovered that the surfatron provides an additional tuning knob for substrate processing. Increasing the power to the surfatron increases the deposition rate. Increasing the frequency applied to the surfatron increases the efficiency of the surfatron in delivering radicals to the process chamber. The inventors have discovered that frequency also plays a role in maintaining the plasma at various pressures. At one frequency value, pressure tuning to all pressure levels is possible, but frequencies above or below that frequency do not allow such a wide range of pressure levels to be used to maintain the plasma. Different dielectric tube configurations can also be used with the surfatron to deliver radicals to different regions of the substrate (e.g., center regions vs. edge regions) and / or at different rates. The surfatron can also be configured to operate, for example, with a first pair with a first dielectric tube and a second pair with a second dielectric tube. Different generators or RF sources can be used to power each pair of surfatrons. Power and frequency can then be used as tuning knobs to vary the amount of radical delivery and / or deposition rate in different areas on the substrate.

[0018]

[0033] In contrast to conventional remote plasma sources, surfatrons operate in an "always on" configuration and do not require special ignition sequences or pressures as conventional remote plasma sources. When plasma is required in the process chamber, the power is increased and the plasma column is extended further through the dielectric tube as needed for radical delivery. Multiple surfatrons can be used in the same dielectric tube to provide uniform plasma intensity throughout the dielectric tube (increasing the length of the plasma column reduces intensity). Depending on the configuration, different reactive gases such as oxygen gas and / or chlorine gas can be injected along with the process gas either directly into the dielectric tube inside the surfatron or directly into the dielectric tube outside the surfatron. The dielectric tube may be configured with nozzles to further disperse and direct the radicals, such as towards a substrate during processing. The surfatron and dielectric tube configuration of the present principles is highly process flexible, highly efficient, and can be retrofitted to and / or into existing chambers.

[0019]

[0034] FIG. 1 is a cross-sectional view of a surfatron assembly 100 having a pass-through dielectric tube 106 that may be used in some embodiments. Other embodiments of the surfatron assembly described below may use a non-pass-through dielectric tube configuration. In operation, the pass-through and non-pass-through configurations generate plasma in a similar manner. Plasma is generated only from the front of the non-pass-through configuration. The operational details currently described are for the pass-through configuration where plasma is provided from both ends of the surfatron assembly. The surfatron assembly 100 is a coaxial structure with a gap 114 of approximately 0.08 inches at one end of the conductive cylinder 104 that encases a portion of the dielectric tube 106. The gap 114 serves as the launch gap for the surface wave 118 within the dielectric tube 106. In the Surfatron assembly 100, a moving electric field 116 is established between the conductive cylinder 104, which is RF hot (connected to RF power via an RF electrode 110 and an RF connector 108), and a ground shield (e.g., the front wall 102 of the Surfatron assembly 100, which is connected to an RF ground 112). The ground shield at the gap 114 is kept thin to prevent choking of the surface waves 118 initiated by the gap 114. In some embodiments, the thickness 150 of the ground shield at the gap 114 is less than about 0.04 inches. In some embodiments, the thickness 150 of the ground shield at the gap 114 is about 0.02 inches. The thin ground shield may form only a portion of the front wall 102 in some embodiments, or may be embedded within the dielectric material of the front wall 102. A dielectric spacer 122 may be used to offset the conductive cylinder 104 from the wall of the Surfatron assembly 100. The dielectric spacer 122 may be formed from a material such as polytetrafluoroethylene (PTFE).

[0020]

[0035] In the launch gap, the direction of the moving electric field 116 is horizontal (from the end of the conductive cylinder 104 to the vertical ground or front wall 102) and parallel to the axial direction 124 of the dielectric tube 106, thereby launching a transverse magnetic surface wave (the direction of the moving electric field 116 is parallel to the propagation direction of the wave (surface wave 118)). The direction of the magnetic field is azimuthal, while the direction of the electric field is axial or radial. The surface wave 118 propagates along the dielectric tube 106, generating a plasma 120 along the way. The length 126 of the column of plasma 120 inside the dielectric tube 106 is a function of power and can be extended to any length based on the amount of input power. In some embodiments, at least one gas supply 140 can be connected to the dielectric tube 106 via at least one gas supply inlet 142, either inside (not shown) or outside (not shown) of the surfatron assembly 100. The gas provided by the gas supply 140 is used in several processes. Some of these processes employ reactive gases to supply radicals into the processing space of a process chamber for processing the substrate. The supply of radicals is typically provided by holes 144 in the bottom or side of the dielectric tube 106. As used herein, "holes" may be construed as relating to actual apertures or may also be construed as relating to nozzles that include apertures and may be used to direct the emission of gas / radicals from the dielectric tube for any or all of the configurations of the present principles.

[0021]

[0036] The inventors have discovered that the Surfatron assembly 100 can operate from approximately 0.01 mTorr to atmospheric pressure and in the megahertz to gigahertz frequency range. The low operating pressure capability of the Surfatron assembly 100 was an unexpected advantage discovered by the inventors. The overall length 128 of the Surfatron assembly 100 can be less than 3 inches. In some embodiments, the length, height, and width are all less than 3 inches. In some embodiments, the overall length 128 can be less than approximately 2.5 inches and the height and width less than 2 inches. In some embodiments, the inner diameter 130 of the dielectric tube 106 can be from approximately 0.2 inches to approximately 20 inches. In some embodiments, the outer diameter 132 of the dielectric tube 106 can be from approximately 0.25 inches to approximately 24 inches. In some embodiments, the thickness 134 of the dielectric tube 106 can be from approximately 0.0625 inches to approximately 4 inches. In some embodiments, the thickness 134 of the dielectric tube 106 may be from about 0.0625 inches to about 0.125 inches. The thickness 134 may be adjusted to maintain the integrity of the dielectric tube wall based on the amount of reduced pressure used during substrate processing. The walls of the dielectric tube 106 provide a reduced pressure boundary between the processing space and the plasma generated inside the dielectric tube 106. A process chamber with a higher reduced pressure for the process may use a dielectric tube 106 with a thinner wall. In some cases, an optional RF match 136 may be used between the surfatron assembly 100 and the RF generator 138. Depending on the size and / or design of the coaxial structure and the operating pressure region, the optional RF match 136 may not be used and only the frequency tuning capability of the RF generator 138 may be used.

[0022]

[0037] FIG. 2 is a top view of a plasma source apparatus 200 including a first surfatron assembly 100A and a second surfatron assembly 100B directly connected together via a dielectric tube 106. In some embodiments, multiple plasma sources or surfatron assemblies may be used. The total number of surfatron assemblies may be three or more. In some embodiments, the outer diameter of the dielectric tube 106 may be from about 0.4 inches to about 6.0 inches. In some embodiments, gas injection ports 202 may be located proximate the first surfatron assembly 100A and the second surfatron assembly 100B to provide process gases and / or reactive gases for the plasma. The holes 144 in the dielectric tube 106 may be of any configuration and number. The holes 144 may be offset, may be both small and large diameter holes, may be holes on the side of the dielectric tube 106, and / or may be holes on the bottom and side of the dielectric tube 106, etc. In some embodiments, the diameter of the holes 144 may range from about 0.04 inches to about 0.4 inches. In some embodiments, as shown in the diagram 300 of FIG. 3, the process uniformity may be improved by adjusting the orientation of the holes 144A, 144B, 144C with respect to the surface 308 of the substrate support 306 (e.g., vertical or bottom holes 144A and vertical or bottom hole central axis 302A with a 90 degree angle 304A with respect to the surface 308, angled holes 144B and angled hole central axis 302B with a 45 degree 304B or other angle with respect to the surface 308 of the substrate support 306, and / or horizontal or side holes 144C and side hole central axis 302C with a 180 degree angle with respect to the surface 308 of the substrate support 306). The holes 144 allow radical delivery to the substrate processing in the process chamber. Advantages of the present principle include: That is, the size and placement of the holes can be adjusted based on the chamber and / or the particular process being used, such as to improve uniformity. In some embodiments, adjustable or directional nozzles can be used at the locations of holes 144A-144C to further adjust the direction of the flow towards surface 308.

[0023]

[0038] Using multiple plasma sources allows for increased control of the radical delivery process. The plasma power to each plasma source can be adjusted together or independently, allowing for an additional knob for the process. In addition, adjusting the plasma power allows for adjustment of the plasma column generated within the dielectric tube 106. The circular shape of the dielectric tube 106 allows it to conform to the shape of the process chamber (either the shape of the internal processing space or the exterior of the process chamber). When the dielectric tube 106 is used in exterior of a process chamber, a nozzle extension 404 from the hole 144 of the dielectric tube 106 that extends through the exterior wall 406 of the process chamber 402 can be used as shown in the top view 400 of FIG. 4.

[0024]

[0039] In the top view 500A of FIG. 5, in some embodiments, the dielectric tube 106 is disposed within the outer wall 406 of the process chamber 402 within the processing space 504. In some embodiments, an optional divider 502 can be used to isolate the first surfatron assembly 100A and the second surfatron assembly 100 from the processing space. The assemblies are thereby isolated from the processing environment and maintained at atmospheric conditions rather than a reduced pressure environment. In the cross-sectional view 500B of FIG. 5, the optional divider 502, the assembly, and the dielectric tube 106 are shown in relation to the substrate support 306 within the process chamber 402. In some embodiments, the circular shape of the dielectric tube 106 can be adjusted to match the substrate diameter to be processed. The circular shape of the dielectric tube 106 can also be smaller in diameter than the substrate diameter. In the top view 600 of FIG. 6, in some embodiments, a further circular section 602 of the dielectric tube is connected to the dielectric tube 106 via a radial section 604. Those skilled in the art will appreciate that other configurations of concentric and radial sections can be used to enhance uniformity by tailoring the delivery of radicals in areas of the substrate where more or less radical density may be required.

[0025]

[0040] FIG. 7 is a cross-sectional view of a surfatron assembly 700 with a non-pass-through dielectric tube 706 that may be used in some embodiments. In operation, the non-pass-through and pass-through configurations generate plasma in a similar manner. Plasma is generated only from the front of the non-pass-through configuration. The surfatron assembly 700 is a coaxial structure with a gap 714 of approximately 0.08 inches at one end of a conductive cylinder 704 that encases a portion of the dielectric tube 706. The gap 714 serves as a launch gap for surface waves 718 within the dielectric tube 706. In the surfatron assembly 700, a traveling electric field 716 is established between the conductive cylinder 704, which is RF hot (connected to RF power via an RF electrode 710 and an RF connector 708), and a ground shield (e.g., the front wall 702 of the surfatron assembly 700, which is connected to an RF ground 712). The ground shield at the gap 714 is kept thin to prevent choking of the surface waves 718 initiated by the gap 714. In some embodiments, the thickness 750 of the ground shield at the gap 714 is less than approximately 0.04 inches. In some embodiments, the thickness 750 of the ground shield at the gap 714 is approximately 0.02 inches. The thin ground shield may form only a portion of the front wall 702 in some embodiments, or may be embedded within the dielectric material of the front wall 702. A dielectric spacer 722 may be used to offset the conductive cylinder 704 from the wall of the Surfatron assembly 700. The dielectric spacer 722 may be formed from a material such as polytetrafluoroethylene (PTFE).

[0026]

[0041] In the launch gap, the direction of the moving electric field 716 is horizontal (from the end of the conductive cylinder 704 to the vertical ground or front wall 702) and parallel to the axial direction 724 of the dielectric tube 706, thereby launching a transverse magnetic surface wave (the direction of the moving electric field 716 is parallel to the propagation direction of the wave (surface wave 718)). The direction of the magnetic field is azimuthal, while the direction of the electric field is axial or radial. The surface wave 718 propagates along the dielectric tube 706, generating a plasma 720 along the way. The length 726 of the column of plasma 720 inside the dielectric tube 706 is a function of power and can be extended to any length based on the amount of input power. In some embodiments, at least one gas supply 740 can be connected to the dielectric tube 706 inside the surfatron assembly 700 via at least one gas supply inlet 742. The gas provided by the gas supply 740 is used in several processes. Some of these processes provide process gases and / or reactive gases to supply radicals into the processing space of a process chamber for processing a substrate, the supply of radicals being typically provided by holes in the bottom or side of the dielectric tube 706 (having similar parameters and orientation as holes 144 described above).

[0027]

[0042] The inventors have discovered that the Surfatron assembly 700 can operate from approximately 0.01 mTorr to atmospheric pressure and in the megahertz to gigahertz frequency range. The low operating pressure capability of the Surfatron assembly 700 was an unexpected advantage discovered by the inventors. The overall length 728 of the Surfatron assembly 700 can be less than 3 inches. In some embodiments, the length, height, and width are all less than 3 inches. In some embodiments, the overall length 728 can be less than approximately 2.5 inches and the height and width less than 2 inches. In some embodiments, the inner diameter 730 of the dielectric tube 706 can be from approximately 0.2 inches to approximately 20 inches. In some embodiments, the outer diameter 732 of the dielectric tube 706 can be from approximately 0.25 inches to approximately 24 inches. In some embodiments, the thickness 734 of the dielectric tube 706 can be from approximately 0.0625 inches to approximately 4 inches. In some embodiments, the thickness 734 of the dielectric tube 706 may be from about 0.0625 inches to about 0.125 inches. The thickness 734 may be adjusted to maintain the integrity of the dielectric tube wall based on the amount of reduced pressure used during substrate processing. The walls of the dielectric tube 706 provide a reduced pressure boundary between the processing space and the plasma generated inside the dielectric tube 706. A process chamber with a higher reduced pressure for the process may use a dielectric tube 706 with a thinner wall. In some cases, an optional RF match 736 may be used between the surfatron assembly 700 and the RF generator 738. Depending on the size and / or design of the coaxial structure and the operating pressure region, the optional RF match 736 may not be used and only the frequency tuning capability of the RF generator 738 may be used.

[0028]

[0043] FIG. 8 is a cross-sectional view of a surfatron assembly 800 having a non-pass-through dielectric tube 806 that may be used in some embodiments. The surfatron assembly 800 is a coaxial structure with a gap 814 of approximately 0.08 inches at one end of a conductive cylinder 804 that encases a portion of the dielectric tube 806. The gap 814 serves as a launch gap for surface waves 818 within the dielectric tube 806. In the surfatron assembly 800, a traveling electric field 816 is established between the conductive cylinder 804, which is RF hot (connected to RF power via an RF electrode 810 and an RF connector 808), and a ground shield (e.g., the front wall 802 of the surfatron assembly 800, which is connected to an RF ground 812). The ground shield at the gap 814 is kept thin to prevent choking of the surface wave 818 initiated by the gap 814. In some embodiments, the thickness 850 of the ground shield at the gap 814 is less than approximately 0.04 inches. In some embodiments, the thickness 850 of the ground shield at the gap 814 is approximately 0.02 inches. The thin ground shield may form only a portion of the front wall 802 in some embodiments, or may be embedded within the dielectric material of the front wall 802 (as shown). A dielectric spacer 822 may be used to offset the conductive cylinder 804 from the wall of the Surfatron assembly 800. The dielectric spacer 822 may be formed from a material such as polytetrafluoroethylene (PTFE).

[0029]

[0044] In the launch gap, the direction of the moving electric field 816 is horizontal (from the end of the conductive cylinder 804 to the vertical ground or front wall 802) and parallel to the axial direction 824 of the dielectric tube 806, thereby launching a transverse magnetic surface wave (the direction of the moving electric field 816 is parallel to the propagation direction of the wave (surface wave 818)). The direction of the magnetic field is azimuthal, while the direction of the electric field is axial or radial. The surface wave 818 propagates along the dielectric tube 806, generating plasma along the way. The length of the column of plasma inside the dielectric tube 806 is a function of power and can be extended to any length based on the amount of input power. In some embodiments, at least one gas supply 840 can be connected to the dielectric tube 806 inside the surfatron assembly 800 via at least one gas supply inlet 842. The gas provided by the gas supply 840 is used in several processes. Some of these processes provide process gases and / or reactive gases to supply radicals into the processing space of a process chamber for processing a substrate, the supply of radicals being typically provided by holes in the bottom or side of the dielectric tube 806 (having similar parameters and orientation as the holes 144 described above).

[0030]

[0045] The inventors have discovered that the surfatron assembly 800 can operate in the megahertz to gigahertz frequency range from approximately 0.01 mTorr to atmospheric pressure. The low operating pressure capability of the surfatron assembly 800 was an unexpected advantage discovered by the inventors. The overall length 828 of the surfatron assembly 800 can be less than 3 inches. In some embodiments, the length, height, and width are all less than 3 inches. In some embodiments, the overall length 828 can be less than approximately 2.5 inches and the height and width less than 2 inches. In some embodiments, the first outer diameter 832 of the dielectric tube 806 of approximately 1.0 inches can be reduced to a second outer diameter 852 of approximately 0.5 inches outside the surfatron assembly 800 to fit into an existing process chamber port. In some embodiments, the inner diameter 830 of the dielectric tube 806 can be from approximately 0.2 inches to approximately 0.75 inches. In some embodiments, the thickness 834 of the dielectric tube 806 may be from about 0.0625 inches to about 0.125 inches. The thickness 834 may be adjusted to maintain the integrity of the dielectric tube wall based on the amount of reduced pressure used during substrate processing. The wall of the dielectric tube 806 provides a reduced pressure boundary between the processing space and the plasma generated inside the dielectric tube 806. A process chamber with a higher reduced pressure for the process may use a dielectric tube 806 with a thinner wall. In some cases, an optional RF match 836 may be used between the surfatron assembly 800 and the RF generator 838. In other cases, depending on the size and / or design of the coaxial structure and the operating pressure region, the optional RF match 836 may not be used and only the frequency tuning capability of the RF generator 838 is used.

[0031]

[0046] Regardless of the configuration of the surfatron assembly (pass-through or non-pass-through), an ultraviolet (UV) filter may be required to prevent UV light from damaging the substrate being processed or causing other process problems. In some embodiments, a UV filter 904 is integrated into the surfatron assembly 902, either internally or externally, as shown in FIG. 9. The UV filter 904 is composed of two separate UV blocking segments (a first or upper segment 912A and a second or lower segment 912B) that are opaque to UV light wavelengths. The two segments are separated by a distance 916 of about 0.5 inches to about 2 inches. This spacing may minimize impedance to gas flow 910 through or from the surfatron assembly 902 into the dielectric tube 906, as shown in FIG. 900A. The UV blocking segments also have an overlap 914 of about 0.25 inches to about 2 inches to ensure that UV light does not enter the dielectric tube 906, as shown in FIG. 900B. The material used for the UV blocking segment must be opaque to UV light wavelengths and maintain any particle or metal contamination requirements for a given process in the process chamber. The UV filter 904 can be made of materials that are opaque to UV light wavelengths, such as silicon, ceramic, black quartz, and / or metal.

[0032]

[0047] FIG. 10 is a cross-sectional view 1000 of a process chamber 1002 having a substrate support 1004 holding a substrate 1006. A gas distribution plate 1008 having distribution holes 1024 separates the substrate support 1004 and the substrate 1006 from a plasma source 1010 located at the top of the process chamber 1002. The gas distribution plate 1008 has a radially equalized flow conductance (e.g., by varying the number of holes in a radial direction) to distribute radicals to the substrate 1006. The plasma source 1010 has a dielectric tube 1028 having a portion surrounded by a conductive cylinder 1012 connected to an RF power source 1022 via an RF electrode 1018 and optionally an RF match network 1020. The dielectric tube 1028 can be formed of quartz or ceramic material with an outer diameter 1060 ranging from approximately 0.25 inches to approximately 20 inches. The thickness of the tube wall is determined based on the diameter of the dielectric tube and / or the operating pressure to maintain mechanical integrity. The plasma source 1010 can have a length of about 2.0 inches to about 20 inches. The plasma source 1010 can operate at a frequency of about 10 MHz to about 3 GHz and at a power range of about 1 Watt to about 5000 Watts.

[0033]

[0048] As mentioned above, the inventors have discovered that the operating pressure range of the plasma source 1010 can be as low as approximately 0.01 mTorr to as high as atmospheric pressure. At least one gas supply 1026 supplies gas into the dielectric tube 1028 via at least one gas supply inlet 1014. The plasma source 1010 is grounded via ground 1016. The UV filter 1030 blocks unwanted UV light from entering the process chamber 1002. The UV filter 1030 can be made of a material that is opaque to UV light wavelengths, such as silicon, ceramic, black quartz, and / or metal. In operation, the plasma source 1010 generates a plasma via a surface wave on the dielectric tube 1028. The plasma projects into the process chamber 1002 and generates radicals from reactive gases supplied via the gas supply 1026 for processing the substrate 1006. The distribution of radical density is substantially determined by the gas distribution plate 1008, the placement of the surfatron above the substrate, and the length of the plasma column extending into the process chamber.

[0034]

[0049] 11 is a cross-sectional view 1100 of a process chamber 1002 having multiple plasma sources 1010 at the top of the process chamber 1002. Utilizing more than one plasma source 1010 facilitates more uniform distribution of the density of radicals generated from the plasma. In this embodiment, both plasma sources 1010 are powered by a common RF power source 1022 via an RF electrode 1018. Each of the plasma sources 1010 may be RF powered by a different RF power source to further facilitate tailoring the radical density within the process chamber 1002. Multiple RF power sources allow the use of different frequencies and different power levels within each of the plasma sources 1010.

[0035]

[0050] FIG. 12 is a cross-sectional view 1200 of a process chamber 1002 having multiple plasma sources 1010 mounted horizontally and symmetrically on the process chamber 1002 to keep the top of the process chamber 1002 free for other and / or existing equipment. This configuration allows the plasma source 1010 of the present principles to be more easily retrofitted into an existing process chamber. Utilizing more than one plasma source 1010 facilitates more uniform distribution of the density of radicals generated from the plasma. In this embodiment, both plasma sources 1010 are powered by a common RF power source 1022 via an RF electrode 1018. Each of the plasma sources 1010 may be RF powered by a different RF power source to further facilitate tailoring the radical density within the process chamber 1002. Multiple RF power sources allow for the use of different frequencies and different power levels within each of the plasma sources 1010.

[0036]

[0051] FIG. 13 is a cross-sectional view 1300 of a process chamber 1002 having a substrate support 1004 holding a substrate 1006. A gas distribution plate 1008 with distribution holes 1024 separates the substrate support 1004 and the substrate 1006 from a plasma source 1010 located on the side of the process chamber 1002. In some embodiments, the gas distribution plate 1008 may have a radially equalized flow conductance (e.g., by varying the number of holes in a radial direction) to distribute radicals to the substrate 1006. The plasma source 1010 is directly connected via an RF electrode 1018 and optionally an RF match network 1020 to a dielectric tube 1328 with a portion of each of the plasma sources surrounded by a conductive cylinder 1012 connected to an RF power source 1022. The dielectric tube 1328 may be formed of quartz or a ceramic material. The plasma source 1010 may operate at frequencies from about 10 MHz to about 3 GHz, and at a power range from about 1 Watt to about 5000 Watts.

[0037]

[0052] As mentioned above, the inventors have discovered that the operating pressure range of the plasma source 1010 can be as low as approximately 0.01 mTorr to as high as atmospheric pressure. The gas supply 1026 supplies gas into the dielectric tube 1328 via the gas supply inlet 1014. The plasma source 1010 is grounded via the ground 1016. In operation, the plasma source 1010 generates plasma in the dielectric tube 1328 via a surface wave. The dielectric tube 1328 extends into the process chamber 1002. Radicals are emitted through holes 1332 in the dielectric tube 1328. The radicals are then distributed by the gas distribution plate 1008. In this configuration, a plasma is generated and maintained inside the dielectric tube 1328. This maximizes the output of radicals. The distribution of the density of radicals is a combination of the holes 1332 in the dielectric tube 1328 and the gas distribution plate 1008.

[0038]

[0053] FIG. 14 is a cross-sectional view 1400 of a process chamber 1002 having a substrate support 1004 holding a substrate 1006. A gas distribution plate 1008 with distribution holes 1024 separates the substrate support 1004 and the substrate 1006 from a plasma source 1010 located at the top of the process chamber 1002. In some embodiments, the gas distribution plate 1008 may have a radially equalized flow conductance (e.g., by varying the number of holes in a radial direction) to distribute radicals to the substrate 1006. The plasma source 1010 is directly connected via an RF electrode 1018 and optionally an RF match network 1020 to a dielectric tube 1428 with a portion of each of the plasma sources surrounded by a conductive cylinder 1012 connected to an RF power source 1022. The dielectric tube 1328 may be formed of quartz or ceramic materials. The plasma source 1010 may operate at a frequency of about 10 MHz to about 3 GHz and at a power range of about 1 Watt to about 5000 Watts. As discussed above, the inventors have discovered that the operating pressure range of the plasma source 1010 may be from a low pressure of about 0.01 mTorr to a high pressure of atmospheric conditions. A gas supply 1026 supplies gas into the dielectric tube 1428 via the gas supply inlet 1014. The plasma source 1010 is grounded via ground 1016.

[0039]

[0054] In operation, the plasma source 1010 generates plasma in the dielectric tube 1428 via surface waves. The dielectric tube 1428 extends into the process chamber 1002. Radicals are emitted via holes 1424 in the dielectric tube 1428. The radicals are then distributed by the gas distribution plate 1008. In this configuration, plasma is generated and maintained inside the dielectric tube 1428. This maximizes the output of radicals. The distribution of radical density is a combination of the holes 1424 in the dielectric tube 1428 and the gas distribution plate 1008. The shape of the dielectric tube extending into the process chamber 1002 can be modified to better distribute radicals within the process chamber 1002 for a given process or type of a given chamber, as shown in FIG. 15. In FIG. 1500A, multiple plasma sources 1010 are positioned above the process chamber 1002. One pair of plasma sources 1010A is directly connected to the outer circular dielectric tube 1502 through a vertical dielectric tube section 1506, and another pair of plasma sources 1010B is connected to the inner circular dielectric tube 1504. The two "rings" can provide better radial uniformity during substrate processing. In FIG. 1500B, a single plasma source 1010 is directly connected to a radial dielectric tube section 1520 connected to a circular dielectric tube section 1522 through a vertical dielectric tube section 1506. In FIG. 1500C, a pair of plasma sources 1010 is directly connected to a circular dielectric tube section 1530 through a horizontal dielectric tube section 1532. Each of the dielectric tube and plasma source configurations can be used to improve the distribution characteristics of radicals to the substrate process.

[0040]

[0055] In the top view 1600 of FIG. 16, a grid configuration of plasma sources 1010 and dielectric tubes provides pixelated radical delivery to the substrate during processing. Each row or column of dielectric tubes 1620 can be powered separately by one or two plasma sources 1010. To reduce the number of RF generators, the plasma sources 1010 can be grouped to control the radial density in the outer region 1604 of the substrate 1602 (e.g., the "G1" plasma source 1010 is powered by a first RF power source), in the middle region 1606 of the substrate 1602 (e.g., the "G2" plasma source 1010 is powered by a second RF power source), and in the central region 1608 of the substrate 1602 (e.g., the "G3" plasma source 1010 is powered by a third RF power source). All configurations of the apparatus of the present principles provide a compact size and highly efficient downstream plasma source that can be easily integrated into any existing process chamber.

[0041]

[0056] Embodiments according to the present principles may be implemented in hardware, firmware, software, or any combination thereof. Also, embodiments may be implemented as instructions stored using one or more computer-readable media, which may be read and executed by one or more processors. A computer-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing platform, or a "virtual machine" running on one or more computing platforms). For example, a computer-readable medium may include any suitable form of volatile or non-volatile memory. In some embodiments, a computer-readable medium may include a non-transitory computer-readable medium.

[0042]

[0057] While the forgoing is directed to embodiments of the present principles, other and further embodiments of the present principles may be devised without departing from the basic scope thereof.

Claims

1. 1. An apparatus having a plasma source, comprising: a chamber having a bottom, a lid, and walls providing a processing space above the substrate support; and a plurality of plasma sources directly interconnected via dielectric tubes; The apparatus, wherein the dielectric tube extends at least partially into the processing space, and the multiple plasma sources are configured to generate surface waves on a wall of the dielectric tube that support plasma generation within the dielectric tube.

2. The apparatus of claim 1 , wherein the multiple plasma sources are disposed within the walls of the chamber and separated from the processing space.

3. The apparatus of claim 1 , wherein one or more of the plurality of plasma sources comprises one or more gas inlets configured to provide a process gas or a reactive gas to an interior of the dielectric tube.

4. 4. The apparatus of claim 3, wherein at least one of the one or more gas inlets is disposed at an opposite end of the one or more of the multiple plasma sources relative to the end where the dielectric tube extends from an end of the one or more of the multiple plasma sources.

5. The apparatus of claim 1 , wherein the dielectric tube comprises one or more gas inlets configured to provide a process gas or a reactive gas to an interior of the dielectric tube.

6. 2. The apparatus of claim 1, wherein the dielectric tube has a plurality of holes or nozzles directed toward the substrate support, the plurality of holes or nozzles configured to emit radicals from within the dielectric tube toward the substrate support.

7. The apparatus of claim 1 , wherein the dielectric tube has a generally circular shape that mimics an outer periphery of the process volume.

8. The apparatus of claim 1 , wherein the dielectric tube has a concentric portion and a radially extending portion connecting the concentric portion.

9. 10. The apparatus of claim 1, wherein the dielectric tube has an outer diameter of less than about 0.5 inches and an inner diameter of less than about 0.3 inches.

10. The apparatus of claim 1 , wherein the chamber is an etch chamber or a deposition chamber.

11. 10. The apparatus of claim 1, wherein at least one of said plurality of plasma sources is a surfatron having a length and width of less than 3 inches.

12. The apparatus of claim 1 , wherein the multiple plasma sources are disposed externally about the walls of the chamber.

13. The apparatus of claim 1 , wherein the plurality of plasma sources are disposed above and external to the lid of the chamber.

14. 10. The apparatus of claim 1, wherein each of the plurality of plasma sources is connected to at least one RF power source that provides RF power to a circular conductive tube that surrounds a portion of the dielectric tube.

15. 1. An apparatus for providing a plasma to a chamber, comprising: a plurality of plasma sources, each having at least a dielectric tube inlet at least partially surrounded by a conductive tube configured to be connected to RF power to generate a plasma, and a gas inlet disposed opposite the dielectric tube inlet; and 11. An apparatus comprising: a dielectric tube directly connected to each of the plurality of plasma sources, the dielectric tube configured to at least partially contain a plasma generated by the plurality of plasma sources, and configured to release radicals generated in the plasma through a hole or nozzle in the dielectric tube, the hole or nozzle in the dielectric tube being disposed within a portion of the dielectric tube configured to be inserted into the chamber.

16. The apparatus of claim 15 , wherein the dielectric tube has a generally circular shape that mimics the periphery of the interior space of the chamber.

17. The apparatus of claim 15 , wherein the dielectric tube has a concentric portion and a radially extending portion connecting the concentric portion.

18. 16. The apparatus of claim 15, wherein the dielectric tube has an outer diameter of less than about 0.5 inches and an inner diameter of less than about 0.3 inches.

19. 16. The apparatus of claim 15, wherein at least one of said plurality of plasma sources is a surfatron having a length and width of less than 3 inches.

20. 1. An apparatus having a plasma source, comprising: a chamber having a base, a lid, and walls providing a processing space above a substrate support; a plurality of plasma sources having an inlet and an outlet for passage of a dielectric tube therethrough, the plurality of plasma sources being disposed within the walls of the chamber and partitioned from direct exposure to the process volume, each plasma source being a Surfetron having a length, width, and height less than 3 inches; An apparatus comprising: a dielectric tube directly connected to each of the plurality of plasma sources, the dielectric tube extending at least partially into the processing space and having one or more gas inlets for gases to generate a plasma within the dielectric tube.

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