The present invention relates to a method and apparatus for utilizing an electrode plate in a plasma processing system and, more particularly, to an electrode plate assembly that facilitates improved maintenance of the plasma processing system.
The fabrication of integrated circuits (IC) in the semiconductor industry typically employs plasma to create and assist surface chemistry within a vacuum processing system necessary to remove material from and deposit material to a substrate. In general, plasma is formed within the processing system under vacuum conditions by heating electrons to energies sufficient to sustain ionizing collisions with a supplied process gas. Moreover, the heated electrons can have energy sufficient to sustain dissociative collisions and, therefore, a specific set of gases under predetermined conditions (e.g., chamber pressure, gas flow rate, etc.) are chosen to produce a population of charged species and chemically reactive species suitable to the particular process being performed within the system (e.g., etching processes where materials are removed from the substrate or deposition processes where materials are added to the substrate).
Although the formation of a population of charged species (ions, etc.) and chemically reactive species is necessary for performing the function of the plasma processing system (i.e. material etch, material deposition, etc.) at the substrate surface, other component surfaces on the interior of the processing chamber are exposed to the physically and chemically active plasma and, in time, can erode. The erosion of exposed components in the processing system can lead to a gradual degradation of the plasma processing performance and ultimately to complete failure of the system.
Therefore, in order to minimize the damage sustained by exposure to the processing plasma, a consumable or replaceable component, such as one fabricated from silicon, quartz, alumina, carbon, or silicon carbide, can be inserted within the processing chamber to protect the surfaces of more valuable components that would impose greater costs during frequent replacement and/or to affect changes in the process. Furthermore, it is desirable to select surface materials that minimize the introduction of unwanted contaminants, impurities, etc. to the processing plasma and possibly to the devices formed on the substrate. Often times, these consumables or replaceable components are considered part of the process kit, which is frequently maintained during system cleaning.
A method and apparatus for utilizing an electrode plate in a plasma processing system is described.
According to one aspect, an electrode plate assembly for introducing process gas to a process space above a substrate in a plasma processing system comprises an electrode configured to be coupled to the plasma processing system, the electrode comprising three or more mounting screws fixedly coupled to the electrode. An electrode plate comprises a plurality of gas injection holes, and three or more mounting holes configured to be aligned with and coupled to the mounting screws in order to couple the electrode plate to the electrode. A plurality of gas injection devices are coupled to the plurality of gas injection holes, wherein the process gas passes through the plurality of gas injection devices into the process space.
According to another aspect, a disposable electrode plate for introducing process gas to a process space above a substrate in a plasma processing system comprises an electrode plate comprising a plurality of gas injection holes, and three or more mounting holes, wherein the electrode plate is configured to be coupled with an electrode by aligning and coupling the three or more mounting holes with three or more mounting screws fixedly attached to the electrode. A plurality of gas injection devices are coupled to the plurality of gas injection holes, wherein the process gas passes through the plurality of gas injection devices into the process space.
Additionally, a method of replacing an electrode plate for introducing process gas to a process space above a substrate in a plasma processing system comprises removing a first electrode plate from the plasma processing system and installing a second electrode plate in the plasma processing system. The first electrode plate and the second electrode plate each comprise a plurality of gas injection holes configured to receive gas injection devices, and three or more mounting holes, wherein each of the first electrode plate and the second electrode plate are configured to be coupled with an electrode in the plasma processing system by aligning and coupling the three or more mounting holes with three or more mounting screws fixedly attached to the electrode.
In the accompanying drawings:
In plasma processing, an electrode plate can, for example, be configured to be mounted on an upper surface of a processing chamber, and to be employed for distributing a process gas to a process space in the processing chamber. For conventional plasma processing systems, the electrode plate is electrically coupled to ground potential, and designed in a shower-head configuration having a plurality of gas injection orifices for uniform distribution of the process gas above a substrate.
According to an embodiment of the present invention, a plasma processing system 1 is depicted in
In the illustrated embodiment, electrode plate assembly 24 comprises an electrode plate 26 and an electrode 28 configured to be coupled to a gas injection assembly, and/or an upper electrode impedance match network. The electrode plate assembly 24 can be coupled to an RF source. In another alternate embodiment, the electrode plate assembly 24 is maintained at an electrical potential equivalent to that of the plasma processing chamber 10. For example, the plasma processing chamber 10, the upper assembly 20, and the electrode plate assembly 24 can be electrically connected to ground potential.
Plasma processing chamber 10 can further comprise an optical viewport 16 coupled to a deposition shield 14. Optical viewport 16 can comprise an optical window 17 coupled to the backside of an optical window deposition shield 18, and an optical window flange 19 can be configured to couple optical window 17 to the optical window deposition shield 18. Sealing members, such as O-rings, can be provided between the optical window flange 19 and the optical window 17, between the optical window 17 and the optical window deposition shield 18, and between the optical window deposition shield 18 and the plasma processing chamber 10. Optical viewport 16 can permit monitoring of optical emission from the processing plasma in process space 12.
Substrate holder 30 can further comprise a vertical translational device 50 surrounded by a bellows 52 coupled to the substrate holder 30 and the plasma processing chamber 10, and configured to seal the vertical translational device 50 from the reduced pressure atmosphere 11 in plasma processing chamber 10. Additionally, a bellows shield 54 can be coupled to the substrate holder 30 and configured to protect the bellows 52 from the processing plasma. Substrate holder 10 can further be coupled to at least one of a focus ring 60, and a shield ring 62. Furthermore, a baffle plate 64 can extend about a periphery of the substrate holder 30.
Substrate 35 can be transferred into and out of plasma processing chamber 10 through a slot valve (not shown) and chamber feed-through (not shown) via robotic substrate transfer system where it is received by substrate lift pins (not shown) housed within substrate holder 30 and mechanically translated by devices housed therein. Once substrate 35 is received from substrate transfer system, it is lowered to an upper surface of substrate holder 30.
Substrate 35 can be affixed to the substrate holder 30 via an electrostatic clamping system. Furthermore, substrate holder 30 can further include a cooling system including a re-circulating coolant flow that receives heat from substrate holder 30 and transfers heat to a heat exchanger system (not shown), or when heating, transfers heat from the heat exchanger system. Moreover, gas can be delivered to the back-side of substrate 35 via a backside gas system to improve the gas-gap thermal conductance between substrate 35 and substrate holder 30. Such a system can be utilized when temperature control of the substrate is required at elevated or reduced temperatures. In other embodiments, heating elements, such as resistive heating elements, or thermo-electric heaters/coolers can be included.
In the embodiment shown in
Alternately, the processing plasma in process space 12 can be formed using a parallel-plate, capacitively coupled plasma (CCP) source, an inductively coupled plasma (ICP) source, any combination thereof, and with and without magnet systems. Alternately, the processing plasma in process space 12 can be formed using electron cyclotron resonance (ECR). In yet another embodiment, the processing plasma in process space 12 is formed from the launching of a Helicon wave. In yet another embodiment, the processing plasma in process space 12 is formed from a propagating surface wave.
Referring now to an illustrated embodiment of the present invention, the electrode plate assembly 24 comprises an electrode plate 26, depicted in
With continuing reference to
Referring still to
The number of gas injection holes 100 formed within electrode plate 26 can range from about 1 to about 10,000. Alternatively, the number of gas injection orifices 100 can range from about 50 to about 500; or the number of gas injection orifices 100 can be at least about 100. Furthermore, a diameter of the gas injection orifice 120 can range from about 0.1 to about 20 mm. Alternatively, the diameter can range from about 0.5 to about 5 mm, or from about 0.5 to about 2 mm. In addition, a length of a gas injection orifice can range from about 0.5 to about 20 mm. Alternatively, the length can range from about 2 to about 15 mm, or from about 3 to about 12 mm.
As described above, the diameter and the length of the gas injection orifice can be varied. For example,
Additionally, the insertion of gas injection devices 110 into the gas injection holes 100 of electrode plate 26 can be performed in such a manner to facilitate a distribution of at least one of orifice diameter, orifice length, and orifice shape across the plasma surface 85 of electrode plate 26. For example, gas injection devices 110 having at least one of an increased diameter, or decreased length can be distributed towards the center of electrode plate 26 in order to increase the flow of process gas to the center of process space 11 relative to the flow of process gas to the edge of process space 11. Alternatively, gas injection devices 110 having at least one of a decreased diameter, or increased length can be distributed towards the center of electrode plate 26 in order to decrease the flow of process gas to the center of process space 11 relative to the flow of process gas to the edge of process space 11.
Referring still to
The electrode plate 26 can be fabricated from at least one of aluminum, coated aluminum, silicon, quartz, silicon carbide, silicon nitride, carbon, alumina, sapphire, Teflon, and polyimide. The electrode plate 26 can, for example, be fabricated using at least one of machining, laser-cutting, grinding, and polishing.
For coated aluminum, the coating can facilitate the provision of an erosion resistant surface when the electrode plate 26 is exposed to harsh processing environments, such as plasma. During fabrication, providing a coating can comprise at least one of providing a surface anodization on one or more surfaces, providing a spray coating on one or more surfaces, or subjecting one or more surfaces to plasma electrolytic oxidation. The coating can comprise at least one of a III-column element and a Lanthanon element. The coating can comprise at least one of Al2O3, Yttria (Y2O3), Sc2O3, Sc2F3, YF3, La2O3, CeO2, Eu2O3, and DyO3. Methods of anodizing aluminum components and applying spray coatings are well known to those skilled in the art of surface material treatment.
All surfaces on electrode plate 26 can be coated, using any of the techniques described above. In another example, all surfaces on electrode plate 26, except for a contact region 83 on second surface 84 as shown in
Additionally, each gas injection device 110 can be fabricated from at least one of aluminum, coated aluminum, silicon, quartz, silicon carbide, silicon nitride, carbon, alumina, sapphire, Teflon, and polyimide. For coated aluminum, the coating can facilitate the provision of an erosion resistant surface when the electrode plate 26 is exposed to harsh processing environments, such as plasma. During fabrication, providing a coating can comprise at least one of providing a surface anodization on one or more surfaces, providing a spray coating on one or more surfaces, or subjecting one or more surfaces to plasma electrolytic oxidation. The coating can comprise at least one of a III-column element and a Lanthanon element. The coating can comprise at least one of Al2O3, Yttria (Y2O3), Sc2O3, Sc2F3, YF3, La2O3, CeO2, Eu2O3, and DyO3. Methods of anodizing aluminum components and applying spray coatings are well known to those skilled in the art of surface material treatment. Each gas injection device 110 can, for example, be fabricated using at least one of machining, laser-cutting, grinding, and polishing.
Referring now to
Additionally, referring to
The electrode 28 can be fabricated from at least one of aluminum, coated aluminum, silicon, quartz, silicon carbide, silicon nitride, carbon, alumina, sapphire, Teflon, and polyimide. The electrode 28 can be fabricated using at least one of machining, laser-cutting, grinding, and polishing.
For coated aluminum, the coating can facilitate the provision of an erosion resistant surface when the electrode 28 is exposed to harsh processing environments, such as plasma. During fabrication, providing a coating can comprise at least one of providing a surface anodization on one or more surfaces, providing a spray coating on one or more surfaces, or subjecting one or more surfaces to plasma electrolytic oxidation. The spray coating can comprise at least one of Al2O3, Yttria (Y2O3), Sc2O3, Sc2F3, YF3, La2O3, CeO2, Eu2O3, and DyO3. The coating can comprise at least one of a III-column element and a Lanthanon element. Methods of anodizing aluminum components and applying spray coatings are well known to those skilled in the art of surface material treatment.
All surfaces on electrode 28 can be coated using any of the techniques described above. In another example, all surfaces on electrode 28, except for a contact region 183 on the rear surface 182 as shown in
In order to provide a vacuum seal between the electrode 28 and the upper assembly 20, the electrode 28 can further comprise a first sealing groove 210, having a dovetail cross-section or rectangular cross-section, on the rear surface 182, as shown in
Additionally, electrode 28 can further comprise an electrical contact feature, wherein the electrical contact feature comprises, for example, an electrical contact groove 220, as shown in
Furthermore, the electrode 28 can further comprise a diagnostics port 230, and a third sealing feature 232 coupled to the coupling surface 182A of the electrode 28 and configured to seal the diagnostics port 230 with the upper assembly 20. As depicted in
Referring now to
In 320, a second electrode plate is installed in the plasma processing system by coupling the second electrode plate to the substrate holder. The second electrode plate can comprise the first electrode plate following refurbishing, or it can be a newly fabricated electrode plate having a plurality of gas injection holes for receiving a plurality of gas injection devices. The refurbishing can include replacing the gas injection devices in the gas injection holes of the first electrode plate. The second electrode plate is coupled to the electrode by aligning each head region of each mounting screw with the insertion opening of each recess slot on the second electrode plate, and rotating the second electrode plate counter-clockwise, as shown in
Although only certain exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention.