Methods and apparatus for symmetrical hollow cathode electrodes and discharge modes in remote plasma processes

Abstract

Methods and apparatus for reducing particle generation in a remote plasma source (RPS), comprising an RPS having a first plasma source having a first electrode and a second electrode, wherein the first and second electrodes are symmetrical about a hollow cavity, the first and second electrodes are configured to induce a hollow cathode effect within the hollow cavity, and wherein the RPS is configured to provide free radicals or ions into a processing space; and a radio frequency (RF) power source configured to provide symmetrical drive waveforms on the first and second electrodes to generate an anode period and a cathode period of the RPS, wherein the anode period and the cathode period operate in a hollow cathode effect mode.

Description

Technical Field

[0001] Embodiments of this principle generally relate to semiconductor chambers used in semiconductor processes. Background Technology

[0002] Some process chambers may include a remote plasma source (RPS) for generating plasma remote from the process chamber, into which free radicals and / or ionized material are delivered. Conventionally, the RPS is connected to the process chamber via a mixing container to mix the process gas stream supplied by the RPS with a diluent (or carrier) gas or other fluid before delivery to the chamber. Ions or free radicals can then be dispersed into the processing space of the process chamber to perform processes such as etching or cleaning. The RPS may include an RF electrode with a hollow cavity and a ground electrode consisting of a flat ground plane. The RF electrode with the hollow cavity generates a hollow cathode mode that enhances electron collisional ionization within the hollow cavity. The ground electrode with the flat ground plane generates a glow discharge mode. The inventors have observed that if a sinusoidal drive system is used for such an RPS, particles may be generated during the glow discharge mode, potentially creating defects on the wafer being processed.

[0003] Therefore, the inventors have provided improved methods and apparatus for generating remote plasmas without producing particles. Summary of the Invention

[0004] This article provides methods and apparatus for reducing particle generation during remote plasma generation.

[0005] In some embodiments, an apparatus for processing a substrate may include: a process chamber having a chamber body surrounding a processing space; a remote plasma source (RPS) having a first plasma source having a first electrode and a second electrode, wherein the first electrode and the second electrode are symmetrical with respect to the hollow cavity, the first electrode and the second electrode being configured to induce a hollow cathode effect within the hollow cavity, and wherein the RPS is configured to provide free radicals or ions into the processing space; and a radio frequency (RF) power source configured to provide symmetrical drive waveforms on the first electrode and the second electrode to generate an anode period and a cathode period of the RPS, the anode period and the cathode period operating in a hollow cathode effect mode.

[0006] In some embodiments, the device may further include: a symmetrical drive waveform that is sinusoidal or square; an isolator located between a first electrode and a second electrode; the isolator having an annular shape; the isolator having at least one groove on the radially inner side of the annular shape, the at least one groove being configured to expose to plasma generated from the first and second electrodes; the isolator being formed of a ceramic material; the first and second electrodes having a hollow cavity having a conical shape having a first end and a second end, the first end having a first diameter opening and the second end having a second diameter opening, wherein the second diameter opening is larger than the first diameter opening; wherein the second diameter opening of the first electrode is configured to face the second diameter opening of the second electrode; a mixing container located between a first plasma source and a processing space; a second plasma source having a third electrode and a fourth electrode, wherein the third and fourth electrodes are symmetrical about the hollow cavity, the third and fourth electrodes being configured to induce a hollow cathode effect within the hollow cavity; and / or wherein the first and second plasma sources provide free radicals or ions into the mixing container, the mixing container being fluidly connected to the processing space.

[0007] In some embodiments, an apparatus for processing a substrate may include: a remote plasma source (RPS) having a first plasma source having a first electrode and a second electrode, wherein the first electrode and the second electrode are symmetrical about a hollow cavity, the first electrode and the second electrode being configured to induce a hollow cathode effect within the hollow cavity; and a radio frequency (RF) power source configured to provide symmetrical drive waveforms on the first electrode and the second electrode to generate an anode period and a cathode period of the RPS, the anode period and the cathode period operating in a hollow cathode effect mode.

[0008] In some embodiments, the device may further include: wherein the symmetrical drive waveform is a sinusoidal waveform or a square wave waveform; an isolator located between a first electrode and a second electrode, wherein the isolator has an annular shape and is formed of a ceramic-based material, and wherein the isolator has at least one groove on the radially inner side of the annular shape, the at least one groove being configured to expose to plasma generated from the first electrode and the second electrode; wherein the first electrode and the second electrode have a hollow cavity having a conical shape having a first end and a second end, the first end having a first diameter opening and the second end having a second diameter opening, wherein the second diameter opening is larger than the first diameter opening; wherein the second diameter opening of the first electrode is configured to face the second diameter opening of the second electrode; and / or a second plasma source having a third electrode and a fourth electrode, wherein the third electrode and the fourth electrode are symmetrical about the hollow cavity, the third electrode and the fourth electrode being configured to induce a hollow cathode effect within the hollow cavity, and wherein the first plasma source and the second plasma source provide free radicals or ions into a mixing container, the mixing container being fluidly connected to the processing space of a process chamber.

[0009] In some embodiments, a method for generating remote plasma for a process chamber may include: generating a symmetrical drive waveform using a radio frequency (RF) power source for a first plasma source; and forming a plasma in the first plasma source by applying the symmetrical drive waveform to a first electrode and a second electrode of the first plasma source, wherein the first electrode and the second electrode are symmetrical about a hollow cavity, and the first electrode and the second electrode are configured to induce a hollow cathode effect within the hollow cavity when driven by the symmetrical drive waveform.

[0010] In some embodiments, the method may further include: forming a plasma in a second plasma source by applying a symmetrical driving waveform to a third and a fourth electrode of the second plasma source, wherein the third and fourth electrodes are symmetrical about a hollow cavity, and the third and fourth electrodes are configured to induce a hollow cathode effect within the hollow cavity when driven by the symmetrical driving waveform; and / or mixing free radicals or ions generated by the first and second plasma sources in a mixing container, the mixing container being fluidly coupled to the processing space of the process chamber.

[0011] Other and further embodiments are disclosed below. Attached Figure Description

[0012] The embodiments of the principle, which are briefly summarized above and discussed in more detail below, can be understood by referring to the illustrative embodiments of the principle drawn in the accompanying drawings. However, the drawings only show typical embodiments of the principle and should therefore not be considered as limiting the scope of the principle, as other equivalent embodiments are permissible.

[0013] Figure 1A schematic cross-sectional view of a process chamber with a remote plasma source according to some embodiments of this principle is depicted.

[0014] Figure 2 A schematic cross-sectional view of a plasma source with symmetrical electrodes according to some embodiments of this principle is depicted.

[0015] Figure 3 A schematic cross-sectional view of a plasma source with symmetrical electrodes and isolators according to some embodiments of this principle is depicted.

[0016] Figure 4 An isometric view of an isolator according to some embodiments of this principle is depicted.

[0017] Figure 5 A schematic cross-sectional view of a remote plasma source having multiple plasma sources with symmetrical electrodes, according to some embodiments of this principle, is depicted.

[0018] Figure 6 A schematic cross-sectional view of a remote plasma source having multiple plasma sources, according to some embodiments of this principle, is depicted.

[0019] Figure 7 This is a method for remotely generating plasma for a process chamber, based on some embodiments of this principle.

[0020] Figure 8 A diagram depicting symmetrical drive waveforms according to some embodiments of this principle is provided.

[0021] Figure 9 Hollow cathode effect cavities according to some embodiments of this principle are described.

[0022] To facilitate understanding, the same reference numerals have been used wherever possible to denote common elements in the accompanying drawings. The drawings are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be beneficially incorporated into other embodiments without further description. Detailed Implementation

[0023] The method and apparatus provide an improved remote plasma source (RPS) with symmetrical hollow electrodes that generate hollow cathode effect modes for the anodic and cathode cycles of a symmetrical RF drive system. The improved RPS eliminates the glow discharge mode of the anodic cycle present in typical RPS systems, which leads to particle generation in the process chamber, resulting in wafer defects and lower wafer yield. The method and apparatus of this principle use a symmetrical electrode configuration and a symmetrical drive voltage waveform to generate the hollow cathode discharge mode. The symmetrical electrode and drive configuration allows for higher power and increased yield without particle generation. Furthermore, eliminating the glow discharge mode increases the lifetime of the RF system by preventing buildup on the isolators used between the electrodes. The symmetrical hollow cavity electrodes can be used with RF power systems with symmetrical drive waveforms ranging from tens of kHz to hundreds of kHz to achieve hollow cathode effect modes for both the cathode and anodic cycles. The inventors have found that the symmetrical waveform has the benefit of neutralizing charged particles accumulated in previous cycles. The symmetrical waveform can include, but is not limited to, sinusoidal or square wave waveforms.

[0024] Some process chambers feature asymmetrical electrode configurations, providing two distinct discharge modes: a glow discharge mode for cathode and anode cycles, and a hollow cathode mode. The inventors have discovered that the glow discharge mode generates particles due to electrode sputtering caused by high-energy ion bombardment. These particles can fall onto the wafer and affect semiconductor performance. Higher RF power has been found to worsen particle performance, severely limiting yield, as RF power must be reduced to improve particle performance and decrease particle generation.

[0025] The methods and apparatus can be used in different types of process chambers, such as pre-cleaning chambers or etching chambers. As an example chamber, Figure 1 A cross-sectional view of a process chamber 100 having a remote plasma source 164 according to some embodiments is depicted. The process chamber 100 is a vacuum chamber adapted to maintain a subatmospheric pressure within an internal space 102 during substrate processing. In some embodiments, the process chamber 100 can maintain a pressure of approximately 1 mTorr to 100 Torr. The process chamber 100 includes a chamber body 104 that surrounds a processing space 108 located in the upper half of the internal space 102. The chamber body 104 may be made of a metal, such as aluminum, etc. The chamber body 104 may be grounded via coupling to a ground 110.

[0026] A substrate support 112 is disposed within the internal space 102 to support and hold a substrate 114 (e.g., a semiconductor wafer) or other such substrate. The substrate support 112 typically includes a base 116 and a hollow support shaft 118 for supporting the base 116. The base 116 may be made of an aluminum-based material or a ceramic-based material, etc. A base formed of a ceramic-based material can be used for high-temperature processes. The hollow support shaft 118 provides conduits to supply the base 116 with, for example, back-side gas, process gas, fluid, coolant, power, etc. In some embodiments, the substrate support 112 includes a focusing ring 120 disposed around the base 116 to enhance process uniformity at the edges of the substrate 114. In some embodiments, the focusing ring 120 is made of a quartz-based material. In some embodiments, the focusing ring 120 is made of a ceramic-based material. Ceramic-based materials are advantageous for high-pressure process capabilities. A slit valve 122 may be coupled to the chamber body 104 to facilitate the transfer of the substrate 114 into and out of the internal space 102.

[0027] In some embodiments, the hollow support shaft 118 is coupled to a lifting actuator 124, such as a motor, which provides vertical movement of the base 116 between an upper processing position and a lower transfer position. The substrate lift 126 may include a lifting rod 128 mounted on a platform 130, connected to a shaft 132 coupled to a second lifting actuator 134 for raising and lowering the substrate lift 126, allowing the substrate 114 to be placed on or removed from the base 116. The base 116 may include a through-hole to receive the lifting rod 128. The hollow support shaft 118 provides a path for a gas conduit 194 for coupling a back-side gas supply 136 and / or an RF power supply 138 to the base 116. In some embodiments, the RF power supply 138 provides bias power to the power conduit 142 to the base 116 via a matching network 140. In some embodiments, the RF energy provided by the RF power supply 138 may have a frequency of approximately 2 MHz or higher. In some embodiments, the RF power supply 138 may have a frequency of approximately 13.56 MHz.

[0028] In some embodiments, a back-side gas supply 136 is disposed outside the chamber body 104 and supplies gas to the base 116. In some embodiments, the base 116 includes a gas passage 144, thereby allowing the gas and the back side of the substrate 114 to interact to maintain a given temperature. The gas passage 144 is configured to supply a back-side gas, such as nitrogen (N), argon (Ar), or helium (He), to the upper surface 146 of the base 116 to act as a heat transfer medium. The gas passage 144 is in fluid communication with the back-side gas supply 136 via a gas conduit 194 to control the temperature and / or temperature distribution of the substrate 114 during use. For example, the back-side gas supply 136 may supply gas during use to cool and / or heat the substrate 1114. In some embodiments, the substrate 114 can be heated from approximately 60 degrees Celsius to approximately 450 degrees Celsius.

[0029] Process chamber 100 includes a process kit surrounding various chamber components to prevent unwanted reactions between these components and contaminants. The process kit includes an upper shield 148. In some embodiments, the upper shield 148 may be made of a metal such as aluminum. In some embodiments, the process kit may be made of quartz. In some embodiments, a mixing container 156 is coupled to and in fluid communication with the processing space 108. The mixing container 156 is also fluidly connected to the RPS 164. The mixing container 156 allows the plasma gas to be mixed with other gases supplied by the gas delivery system 150. The flow rate of the other gases from the gas delivery system 150 may be controlled by a first flow valve 188.

[0030] Nozzle 158 is located above processing space 108 and below top plate 162 of chamber body 104. Nozzle 158 includes through-hole 160 to allow gas to flow from mixing container 156 into processing space 108. RPS 164 is fluidly connected to mixing container 156 to allow ionized gas to flow from RPS 164 into mixing container 156, through nozzle 158, and into processing space 108. Plasma is generated in RPS 164 by plasma RF power source 166, which provides RF energy to RPS 164. Process gas for plasma formation is supplied by process gas source 170 and controlled by second flow valve 186. Plasma gas supplied by process gas source 170 may include, but is not limited to, hydrogen, helium, and / or argon. RPS 164 generates ions and radicals of process gas to promote processing substrate 114.

[0031] Pump port 172 is configured to facilitate the removal of particles and gases from the internal space 102. Process chamber 100 is coupled to and in fluid communication with vacuum system 174, which includes a throttle valve (not shown) and a pump (not shown) for venting process chamber 100. In some embodiments, vacuum system 174 is coupled to pump port 172 disposed on the bottom surface 176 of chamber body 104. Pressure within process chamber 100 can be regulated by adjusting the throttle valve and / or the vacuum pump. In some embodiments, the pump has a flow rate of approximately 1900 liters per second to approximately 3000 liters per second. In some embodiments, vacuum system 174 can be used to facilitate the regulation of substrate temperature.

[0032] In some embodiments, controller 178 is used for the operation of process chamber 100. Controller 178 may use direct control of process chamber 100, or alternatively, indirect control of process chamber 100 by controlling a computer (or controller) associated with processing process chamber 100. In operation, controller 178 enables the collection of data and feedback from process chamber 100 to optimize the performance of process chamber 100. Controller 178 generally includes a central processing unit (CPU) 180, memory 182, and support circuitry 184. CPU 180 may be any form of general-purpose computer processor that can be used in an industrial environment. Support circuitry 184 is conventionally coupled to CPU 180 and may include cache, clock circuitry, input / output subsystems, power supply, etc. Software routines (such as those described below) may be stored in memory 182 and, when executed by CPU 180, transform CPU 180 into a general-purpose computer (controller 178). The software routines may also be stored and / or executed by a second controller (not shown) located away from the process chamber 100.

[0033] The memory 182 is in the form of a computer-readable storage medium that includes instructions that, when executed by the CPU 180, facilitate the operation of semiconductor processes and devices. The instructions in the memory 182 are in the form of a program product (such as a program) that implements the methods of this disclosure. The program code may conform to any of several different programming languages. In one example, this disclosure may be implemented as a program product stored on a computer-readable storage medium and used with a computer system. The program(s) of the program product define aspects of the embodiments (including the methods described herein). Illustrative computer-readable storage media include (but are not limited to): (1) a non-writable storage medium (e.g., a read-only memory device within a computer, such as an optical disc readable by a CD-ROM drive, flash memory, ROM wafer, or any type of solid-state non-volatile semiconductor memory) on which information is permanently stored; and (2) a writable storage medium (e.g., a disk or hard disk drive within a magnetic tape drive or any type of solid-state random access semiconductor memory) on which changeable information is stored. This computer-readable storage medium, when loaded with computer-readable instructions instructing the function of the methods described herein, is an embodiment of this disclosure.

[0034] Figure 2 A cross-sectional view of a plasma source 200 having an upper symmetric electrode 202A and a lower symmetric electrode 202B according to some embodiments is depicted. During operation of the RPS 164, gas enters through gas port 210, and plasma-related products exit through diffuser 208 into mixing container 156. Diffuser 208 may have a diameter of approximately 0.1 inches to approximately 0.2 inches. The upper symmetric electrode 202A and the lower symmetric electrode 202B have corresponding upper symmetric cavities 204A and 204B, which are configured to produce a hollow cathode effect. The upper symmetric electrode 202A and the lower symmetric electrode 202B are separated by a gap 206. The gap 206 can separate the upper symmetric electrode 202A and the lower symmetric electrode 202B by a distance of approximately 0.2 inches to approximately 0.5 inches. The upper symmetric cavity 204A and the lower symmetric cavity 204B have a conical shape 902, as shown in the figure. Figure 9 As shown in the isometric view. Figure 9 A hollow cathode effect cavity 900 according to some embodiments is depicted.

[0035] exist Figure 9In the cone shape 902, a vertical axis 904 is located at the center. A first end 910 is an opening fluidly connected to a gas supply (e.g., process gas source 170). The opening at the first end 910 may have a diameter of approximately 0.1 inches to approximately 0.2 inches. A second end 912 is a larger flared opening fluidly connected to a gap 206 between the upper symmetrical electrode 202A and the lower symmetrical electrode 202B. In some embodiments, the cone shape 902 may have a first conical portion 914 having a first angle 906 of approximately 10 degrees to approximately 30 degrees. In some embodiments, the cone shape 902 may have a second conical portion 916 having a larger opening with a second angle 908 of approximately 10 degrees to approximately 60 degrees. In some embodiments, the height 918 of the cone shape 902 may be approximately 1.5 inches to approximately 2 inches.

[0036] Plasma RF power source 166 generates a symmetrical drive waveform 802 (e.g., a sine wave, shown as a non-limiting example), such as Figure 8 As shown in Figure 800, during the cathode cycle 806, plasma 212 is formed in a hollow cathode mode caused by the upper symmetric cavity 204A. During the anode cycle 804, plasma 212 is formed in a hollow cathode mode caused by the lower symmetric cavity 204B. In a conventional system with a ground plane for the lower electrode, the anode cycle 804 would instead produce a glow discharge mode due to the ground plane, generating particles detrimental to semiconductor performance. Utilizing the upper symmetric electrode 202A and lower symmetric electrode 202B based on this principle, particle performance is significantly improved. During testing, the inventors found that when the upper symmetric cavity 204A and lower symmetric cavity 204B are configured to produce a hollow cathode effect, RPS 164 exhibits superior particle performance compared to RPS with parallel planar electrodes, which produces glow discharge for both the anode and cathode cycles of the symmetric drive waveform 802.

[0037] During other tests, the inventors discovered that when the top electrode with a hollow cavity and the bottom electrode, which serves as a flat plate electrode, are used as ground (i.e., "asymmetric electrodes"), two different plasma modes are generated when the plasma source is driven with a symmetrical waveform. During the anode cycle 804, a thin plasma forms directly above the top of the flat plate electrode used as ground. During the cathode cycle 806, a strong hollow cathode effect occurs at the center of the hollow cavity of the top electrode, forming plasma at the center ("hollow cathode effect"). The inventors found that the hollow cathode mode improves etching performance. When the driving waveform is changed so that only the cathode cycle (half-sine waveform) exists, the inventors found that etching performance is improved, but also found a negative impact of material buildup in the gap between the top and bottom electrodes separating the plasma source.

[0038] When the electrodes are replaced with parallel planar electrodes with gaps between them, glow discharge modes occur in both the anode and cathode cycles, leading to decreased etching performance and the generation of a large number of particles. The inventors discovered that using a symmetrical electrode with a hollow cavity configured to generate a hollow cathode effect mode in both the anode and cathode cycles significantly improves etching performance compared to a single conical hollow electrode. In some embodiments, a ceramic ring (see below) Figure 3 To further reduce glow discharge modes in gap 206, wherein the electrodes form parallel surfaces 220 (away from the conical hollow cavity). In some embodiments, a ceramic coating 222 is applied to at least one of the parallel surfaces 220 (top parallel surface 220A of the top electrode or bottom parallel surface 220B of the bottom electrode) to further reduce glow discharge modes in gap 206 (away from the conical cavity) where the electrodes form parallel surfaces 220.

[0039] Figure 3 A cross-sectional view of a plasma source 300 having an optional isolator 302 between an upper symmetric electrode 202A and a lower symmetric electrode 202B, according to some embodiments, is depicted. The inventors have found that using an optional isolator 302 in the gap 206 helps reduce particle buildup on the surface of the gap 206 by reducing the electric field between the upper symmetric electrode 202A and the lower symmetric electrode 202B. In some embodiments, the optional isolator 302 may be annular and formed of a ceramic-based material. Optional grooves 304 may be formed in the inner surface 402 of the optional isolator 302 to increase the surface area on the interior of the optional isolator 302. In some embodiments, more than one optional groove 304 may be formed in the inner surface 402 of the optional isolator 302. In some cases, nickel buildup may occur on the inner surface 402 of the optional isolator 302. The addition of optional grooves 304 increases the surface area of ​​the inner surface 402, thereby reducing arcing through nickel buildup and preventing discharge between the upper symmetric electrode 202A and the lower symmetric electrode 202B. Figure 4 An isometric view 400 depicts an optional isolator 302 according to some embodiments. The inner surface 402 may also have one or more optional grooves (not shown, see...). Figure 3 ).

[0040] Compared to the hollow cavity during operation, the parallel surface 220 of the gap 206 has a very strong electric field strength. This strong electric field strength generates high ion energy, which forces ions to repeatedly bombard the parallel surface 220, sputtering material from the electrode surface. In some embodiments, the electrode is formed of or coated with a nickel-based material, and then the electrode is sputtered by high-energy ions in the parallel surface region of the gap. Due to ion bombardment, sputtering may produce nickel particles or nickel deposits. Sputtering can be reduced or eliminated by using an optional isolator 302 or a ceramic coating 222 to reduce the electric field. The inventors have found that by reducing the electric field in the parallel surface region of the gap, more current will flow through the hollow cavity region and amplify the hollow cathode effect of the hollow cavity, thereby significantly improving etching performance. For example, the inventors have found that using symmetrical electrodes can increase the etching rate by approximately 20% to approximately 40%. By reducing the electric field in the parallel surface region of the gap 206, the inventors have found that the etching rate can be increased by 500% or more.

[0041] Figure 5 A cross-sectional view of a remote plasma source 500 having multiple plasma sources 164A, 164B with symmetrical electrodes is depicted according to some embodiments. By using two or more plasma sources in the RPS 500, yield can be increased. In some embodiments, the multiple plasma sources 164A, 164B are mounted to a dome-shaped top plate 502 of a mixing vessel 156A. The dome-shaped top plate 502 allows the multiple plasma sources 164A, 164B to be mounted at an angle that allows connection of multiple units that feed the mixing vessel 156A. The plasma RF power system 504 may have one or more plasma RF power sources 506A, 506B, which may provide power independently or in combination, as determined by the power controller 508. Figure 6 A cross-sectional view of a remote plasma source 600 having multiple plasma sources 602A, 602B according to some embodiments is depicted. Increased yield, but without the advantage of having symmetrical electrodes.

[0042] Figure 7This is a method 700 for remotely generating plasma for a process chamber according to some embodiments. In block 702, a symmetrical drive waveform is generated by an RF power source for a first plasma source in the RPS. In some embodiments, the symmetrical drive waveform may be a sine wave or a square wave, etc. The symmetrical waveform has the benefit of neutralizing charged particles accumulated in previous cycles. In block 704, plasma is formed in the first plasma source by applying the symmetrical drive waveform to a first electrode and a second electrode of the first plasma source. The first and second electrodes are symmetrical and have hollow cavities, and are configured to induce a hollow cathode effect within the hollow cavities when driven by the symmetrical drive waveform. In some embodiments, ions and / or radicals from the plasma flow into a mixing container, in which additional gases may be mixed. The resulting mixture then flows into the processing space of the process chamber to process the substrate.

[0043] In some embodiments, more than one plasma source may be used. Although the example here may show two plasma sources for simplicity, any number of plasma sources may be used. In optional block 706, plasma is formed in the second plasma source by applying a symmetrical drive waveform to a third electrode and a fourth electrode of the second plasma source. The third and fourth electrodes are symmetrical and have hollow cavities, and are configured to induce a hollow cathode effect within the hollow cavities when driven by the symmetrical drive waveform. In optional block 708, radicals or ions generated by the first and second plasma sources are mixed in a mixing container, which is fluidly coupled to the processing space of the process chamber. The mixing of the two plasma sources allows for increased RPS yield and / or ion / radical density.

[0044] Embodiments based on this principle can be implemented in hardware, firmware, software, or any combination thereof. Embodiments can also be implemented as instructions stored using one or more computer-readable media, which can be read and executed by one or more processors. The computer-readable media may include any mechanism for storing or transferring information in a machine-readable form (e.g., a computing platform or a “virtual machine” executing on one or more computing platforms). For example, the computer-readable media may include any suitable form of volatile or non-volatile memory. In some embodiments, the computer-readable media may include a non-transient computer-readable media.

[0045] While the foregoing describes embodiments of the principle, other and further embodiments of the principle may be conceived without departing from the basic scope of the foregoing.

Claims

1. An apparatus for processing a substrate, comprising: A process chamber, the process chamber having a chamber body, the chamber body surrounding a processing space; A remote plasma source (RPS) having a first plasma source having a first electrode and a second electrode, wherein the first electrode and the second electrode are symmetrical about a hollow cavity having a conical shape, the first electrode and the second electrode are configured to induce a hollow cathode effect within the hollow cavity, and wherein the RPS is configured to provide free radicals or ions into the processing space. as well as A radio frequency (RF) power source configured to provide symmetrical drive waveforms on the first and second electrodes to generate an anode and cathode cycle of the RPS, the anode and cathode cycles operating in a hollow cathode effect mode.

2. The device as claimed in claim 1, wherein the symmetrical drive waveform is a sine wave or a square wave.

3. The device of claim 1, further comprising: An isolator located between the first electrode and the second electrode.

4. The device of claim 3, wherein the isolator has an annular shape.

5. The device of claim 4, wherein the isolator has at least one groove on the radially inner side of the annular shape, the at least one groove being configured to be exposed to the generated plasma from the first electrode and the second electrode.

6. The device of claim 3, wherein the isolator is formed of a ceramic material.

7. The device of claim 1, wherein the first electrode and the second electrode have a hollow cavity, the hollow cavity having the conical shape, the conical shape having a first end and a second end, the first end having a first diameter opening, the second end having a second diameter opening, wherein the second diameter opening is larger than the first diameter opening.

8. The device of claim 7, wherein the second diameter opening of the first electrode is configured to face the second diameter opening of the second electrode.

9. The device of claim 1, further comprising: A mixing container located between the first plasma source and the processing space.

10. The device of claim 1, further comprising: A second plasma source having a third electrode and a fourth electrode, wherein the third electrode and the fourth electrode are symmetrical about a hollow cavity, and the third electrode and the fourth electrode are configured to induce a hollow cathode effect within the hollow cavity.

11. The apparatus of claim 10, wherein the first plasma source and the second plasma source provide free radicals or ions into the mixing container, the mixing container being fluidly connected to the processing space.

12. An apparatus for processing a substrate, comprising: A remote plasma source (RPS) having a first plasma source having a first electrode and a second electrode, wherein the first electrode and the second electrode are symmetrical about a hollow cavity having a conical shape, and the first electrode and the second electrode are configured to induce a hollow cathode effect within the hollow cavity; as well as A radio frequency (RF) power source configured to provide symmetrical drive waveforms on the first and second electrodes to generate an anode and cathode cycle of the RPS, the anode and cathode cycles operating in a hollow cathode effect mode.

13. The device of claim 12, wherein the symmetrical drive waveform is a sine wave or a square wave.

14. The apparatus of claim 12, further comprising: An isolator located between a first electrode and a second electrode, wherein the isolator has an annular shape and is formed of a ceramic-based material, and wherein the isolator has at least one groove on the radially inner side of the annular shape, the at least one groove being configured to be exposed to plasma generated from the first electrode and the second electrode.

15. The device of claim 12, wherein the first electrode and the second electrode have a hollow cavity, the hollow cavity having the conical shape, the conical shape having a first end and a second end, the first end having a first diameter opening, the second end having a second diameter opening, wherein the second diameter opening is larger than the first diameter opening.

16. The device of claim 15, wherein the second diameter opening of the first electrode is configured to face the second diameter opening of the second electrode.

17. The apparatus of claim 12, further comprising: A second plasma source having a third electrode and a fourth electrode, wherein the third electrode and the fourth electrode are symmetrical about a hollow cavity, the third electrode and the fourth electrode are configured to induce a hollow cathode effect within the hollow cavity, and wherein the first plasma source and the second plasma source provide free radicals or ions into a mixing container, the mixing container being fluidly connected to the processing space of a process chamber.

18. A method for generating a remote plasma for a process chamber, comprising: A symmetrical drive waveform is generated using a radio frequency (RF) power source for the first plasma source; as well as Plasma is formed in the first plasma source by applying the symmetrical driving waveform to the first and second electrodes of the first plasma source, wherein the first and second electrodes are symmetrical about a hollow cavity having a conical shape, and the first and second electrodes are configured to induce a hollow cathode effect in the hollow cavity when driven by the symmetrical driving waveform.

19. The method of claim 18, further comprising: Plasma is formed in the second plasma source by applying the symmetrical driving waveform to the third electrode and the fourth electrode, wherein the third electrode and the fourth electrode are symmetrical about the hollow cavity and are configured to induce a hollow cathode effect in the hollow cavity when driven by the symmetrical driving waveform.

20. The method of claim 19, further comprising: Free radicals or ions generated by the first plasma source and the second plasma source are mixed in a mixing container, which is fluidly coupled to the processing space of the process chamber.

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