Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
  • H05H1/00—Generating plasma; Handling plasma
  • H05H1/24—Generating plasma
  • H05H1/46—Generating plasma using applied electromagnetic fields, e.g. high frequency or microwave energy
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32431—Constructional details of the reactor
  • H01J37/32532—Electrodes
  • H01J37/32541—Shape
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32431—Constructional details of the reactor
  • H01J37/32715—Workpiece holder
  • H01J37/32724—Temperature

Definitions

• the present invention relates generally to plasma processing and, more particularly, to plasma processing chambers and electrode assemblies used therein.
• Plasma processing apparatuses can be used to process substrates by a variety of techniques including, but not limited to, etching, physical vapor deposition, chemical vapor deposition, ion implantation, resist removal, etc.
• one type of plasma processing chamber contains an upper electrode, commonly referred to as a showerhead electrode, and a bottom electrode. An electric field is established between the electrodes to excite a process gas into the plasma state to process substrates in the reaction chamber.
• an electrode assembly comprises a thermal control plate, a silicon-based showerhead electrode, a thermally conductive gasket, and a plurality of o-rings.
• the thermal control plate comprises a frontside, a backside, and a plurality of process gas passages
• the showerhead electrode comprises a frontside, a backside, and a plurality of showerhead passages.
• the thermal control plate and the showerhead electrode are engaged such that the frontside of the thermal control plate faces the backside of the showerhead electrode, while the plurality of process gas passages of the thermal control plate and the plurality of showerhead passages of the showerhead electrode cooperate to permit passage of a process gas through the electrode assembly.
• the respective profiles of the frontside of the thermal control plate and the backside of the showerhead electrode cooperate to define a thermal interface.
• the thermally conductive gasket and the o-rings are positioned along this thermal interface with the o-rings separating the thermally conductive gasket from the showerhead passages such that the gasket is isolated from the showerhead passages.
• a plasma processing chamber comprising a vacuum source, a process gas supply, a plasma power supply, a substrate support, and an upper electrode assembly fabricated to incorporate one or more of the aspects of the present invention.
• Fig. 1 is a schematic illustration of a plasma processing chamber incorporating particular aspects of some embodiments of the present invention
• Fig. 2 is a plain view of the backside of a showerhead electrode according to one embodiment of the present invention
• Fig. 3 is an isometric illustration of the backside and thickness dimensions of a showerhead electrode according to one embodiment of the present invention
• Fig. 4 is a cross sectional illustration of an electrode assembly according to one embodiment of the present invention.
• Fig. 5 is a magnified illustration of the electrode assembly shown in Fig. 4.
• the various aspects of the present invention can be illustrated in the context of a plasma processing chamber 10, which is merely illustrated schematically in Fig. 1 to avoid limitation of the concepts of the present invention to particular plasma processing configurations, or components, that may not be integral to the subject matter of the present invention.
• the plasma processing chamber 10 comprises a vacuum source 20, a process gas supply 30, a plasma power supply 40, a substrate support 50 including a lower electrode assembly 55, and an upper electrode assembly 60.
• the electrode assembly 60 comprises a thermal control plate 70, a silicon-based showerhead electrode 80, a thermally conductive gasket 90, and a plurality of o-rings 100.
• the thermal control plate 70 comprises a frontside 72, a backside 74, and a plurality of process gas passages 76. These process gas passages 76 typically extend from the backside 74 through the frontside 72 of the thermal control plate 70.
• suitable thermal control plate materials include aluminum, aluminum alloys, or similar thermal conductors.
• a variety of teachings may be relied upon in the design of thermal control plates including, but not limited to, U.S. Pub. No. 2005/0133160.
• the silicon-based showerhead electrode 80 shown in Figs. 2-5, comprises a backside 82, a frontside 84, and a plurality of showerhead passages 86. These showerhead passages 86 typically extend from the backside 82 through the frontside 84 of the showerhead electrode 80.
• suitable showerhead electrode materials include, but are not limited to, single crystal silicon, polysilicon, silicon nitride, silicon carbide, boron carbide, aluminum nitride, aluminum oxide, or combinations thereof.
• the silicon-based showerhead electrode 80 may be presented in a variety of configurations without departing from the scope of the present invention including, but not limited to, a single-piece, circular showerhead configurations or multi-component, circular showerhead configurations comprising a circular central electrode and one or more peripheral electrodes arranged about the circumference of the central electrode.
• the thermal control plate 70 and the showerhead electrode 80 are engaged such that the frontside 72 of the thermal control plate 70 faces the backside 82 of the showerhead electrode 80.
• the plurality of process gas passages 76 of the thermal control plate 70 and the plurality of showerhead passages 86 of the showerhead electrode 80 cooperate to permit passage of a process gas through the electrode assembly 60.
• the electrode assembly 60 is configured such that the respective profiles of the frontside 72 of the thermal control plate 70 and the backside 82 of the showerhead electrode 80 cooperate to define a thermal interface 110.
• the thermally conductive gasket 90 is positioned along the thermal interface 110 between the frontside 72 of the thermal control plate and the backside 82 of the showerhead electrode 80. It is contemplated that multiple thermally conductive gaskets 90 may be positioned along the thermal interface 110, however, generally, only a single gasket 90 is positioned along the thermal interface 110.
• the positioning of the thermally conductive gasket 90 along the thermal interface 110 between the frontside 72 of the thermal control plate 70 and the backside 82 of the showerhead electrode 80 facilitates in the transfer of heat across the thermal interface 110 from the showerhead electrode 80 to the thermal control plate 70, generally under low contact pressure conditions.
• the temperature of the silicon- based showerhead electrode 80 increases due to ion bombardment from the plasma.
• the thermally conductive gasket 90 facilitates heat transfer from the showerhead electrode 80 to the thermal control plate 70.
• thermally conductive gasket 90 may facilitate the transfer of heat across the thermal interface from the thermal control plate 70 to the showerhead electrode 80, generally under low contact pressure conditions, in order to maintain the showerhead electrode 80 at a specified temperature when not in use.
• the thermally conductive gasket 90 is in direct communication with the frontside 72 of the thermal control plate 70 and the backside 82 of the showerhead electrode 80.
• This direct communication of the thermally conductive gasket 90 with the frontside 72 of the thermal control plate 70 and the backside 82 of the showerhead electrode 80 promotes communication between the backside 82 of the showerhead electrode 80 and the frontside 72 of the thermal control plate 70 under low contact pressure such that the gasket 90 facilitates heat transfer across the thermal interface 110 defined by the showerhead electrode 80 and the thermal control plate 70.
• the gasket 90 generally is configured substantially of a thermally conductive material.
• the gasket may be a composite of aluminum foil coated with a thermally and electrically conductive rubber.
• the thermally conductive material may also be electrically conductive.
• the thermally conductive gasket 90 comprises carbon nanotube fillers. It is contemplated, however, that numerous other thermally, electrically conductive gaskets may be utilized in embodiments of the present invention to effectively transfer heat across the thermal interface 110.
• the electrode assembly 60 generally further comprises a plurality of o-rings 100.
• the o-rings 100 also are positioned along the thermal interface 110 and separate the gasket 90 from the showerhead passages 86 such that the gasket 90 is isolated from the showerhead passages 86 and, thus, also the process gas that may pass therethrough.
• isolated means that the thermally conductive gasket 90 is both entirely physically separated from and at least substantially pneumatically sealed off from the showerhead passages and the process gas that may pass therethrough.
• the o-rings 100 are configured to substantially prevent wearing of the gasket 90 through movement of the showerhead electrode 80, the thermal control plate 70, or both, and substantially prevent particles generated from the wearing of the gasket 90 from entering the showerhead passages 86.
• dramatic temperature changes in electrode assemblies which are often associated with plasma processing, may cause movement of the showerhead electrode 80, the thermal control plate 70, or both.
• the molecular expansion and contraction of the showerhead electrode 80, the thermal control plate 70, or both, caused by changes in temperature can wear the gasket 90 positioned in the thermal interface 110 between showerhead electrode 80 and the thermal control plate 70, potentially causing particulate matter of the gasket 90 to slough off.
• a plasma processing chamber 10 comprises a vacuum source 20, a process gas supply 30, a plasma power supply 40, a substrate support 50, and an upper electrode assembly 60.
• the vacuum source 20 is configured to at least partially evacuate the plasma processing chamber 10.
• the substrate support 50 is positioned in an evacuated portion 15 of the plasma processing chamber 10 and comprises a substrate electrode spaced from the upper electrode assembly 60.
• the substrate electrode and the upper electrode assembly 60 are operatively coupled to the plasma power supply 40.
• the upper electrode assembly 60 utilized in the plasma processing chamber 10 may be one of any embodiment of the electrode assembly 60 apparent in the detailed description and the claims of the present application.
• the plasma processing chamber 10 may comprise an electrode assembly defining a thermal interface 110 and comprising o-rings 100 positioned along the thermal interface 110 that separate a thermally conductive gasket from showerhead passages 86 of the electrode assembly 60.
• the upper electrode assembly 60 within the plasma processing chamber 10 generally defines a hermetically sealed plasma partition 65 such that gas and reactive species within the evacuated portion 15 of the plasma processing chamber 10 do not penetrate beyond the plasma partition 65 and interfere with the operation of the electrode assembly 60 and/or the plasma processing chamber 10.
• the particular manner in which the plasma partition 65 is defined will vary depending on the respective configurations of the thermal control plate 70 and the showerhead electrode 80. It is contemplated that, in most cases, the respective materials forming the thermal control plate 70 and the showerhead electrode 80 will define the majority of the partition 65. In addition, it is contemplated that a variety of sealing members can be used to enhance the partition 65, particularly where the thermal control plate 70 and the showerhead electrode 80 interface with each other and with other components of the plasma processing chamber 10.
• the electrode assembly 60 generally also comprises securing hardware 120.
• the thermal control plate 70 may comprise securing hardware passages 78 that are configured to permit securing hardware 120 to access the backside inserts 88 positioned in the partial recesses 89 along the backside 82 of the silicon-based showerhead electrode 80.
• the thermal control plate 70 and the silicon-based showerhead electrode 80 can be engaged using the securing hardware 120 and the backside inserts 88.
• the securing hardware passages 78 are aligned with the backside inserts 88 positioned in the partial recesses 89 along the backside 82 of the showerhead electrode 80.
• the securing hardware 120 may extend through the securing hardware passages 78 in the thermal control plate 70 and engage the backside inserts 88, which are positioned in the partial recesses 89 along the backside 82 of the showerhead electrode 80.
• the securing hardware 120 and the backside inserts 88 are configured to maintain engagement of the thermal control plate 70 and the silicon-based showerhead electrode 80 and to permit repeated, nondestructive engagement and disengagement of the thermal control plate 70 and the showerhead electrode 80.
• the backside insert 88 can be configured as a stud comprising a backside extension 88 A that is configured to extend into one of the securing hardware passages 78 in the thermal control plate 70.
• the securing hardware 120 is configured to access the backside extension 88A of the backside insert 88 in the securing hardware passage 78 via, for example, a threaded engagement.
• the backside inserts 88 can be configured as anchors in the partial recesses 89 formed in the backside 82 of the showerhead electrode 80.
• the securing hardware 120 which may for example comprise a threaded screw or bolt, engages the backside insert 88 to secure the showerhead electrode 80 to the thermal control plate 70.
• any of the embodiments disclosed herein employing one or more backside inserts 88 it will often be advantageous to ensure that the securing hardware 120, the backside inserts 88, and the partial recess 89 are configured such that, during thermal loading, with the securing hardware 120 and backside insert 88 in an engaged state, the backside insert
• the insert 88 is able to move with the securing hardware 120 within the partial recess 89 without dislodging from the recess 89. Accordingly, in another embodiment, the insert 88 can be secured in the recess 89 in a spring-loaded state by providing a spring, the insert 88 being configured to allow for movement of the insert 88 in the partial recess 89 in the spring-loaded state. As a result, during the thermal loading typically present in plasma processing, the backside insert 88 can move with the securing hardware 120 within the partial recess 89 without dislodging from the recess 89 and without degrading the engagement of the securing hardware 120 and the insert 88.
• the backside insert 88 is configured as an anchor in one of the partial recesses
• the 89 formed in the backside 82 of the showerhead electrode 80 and the securing hardware 120 comprises a spring element in the form of a spring-loaded washer configured to oppose a force of engagement provided when the securing hardware 120 accesses the backside insert 88.
• the backside insert 88 may be omitted in favor of direct threaded engagement with a tapped hole in the electrode material.
• the spring element can be provided as a helical spring arranged about a longitudinal extension of the securing hardware 120 in the securing hardware passage 78.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Electromagnetism (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Chemical Vapour Deposition (AREA)
• Drying Of Semiconductors (AREA)
• Plasma Technology (AREA)

Priority Applications (2)

Applications Claiming Priority (6)

Publications (2)

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• 2008
  • 2008-04-30 US US12/112,112 patent/US8216418B2/en active Active
  • 2008-05-22 CN CN2008800201639A patent/CN101715605B/zh active Active
  • 2008-05-22 JP JP2010512243A patent/JP5341073B2/ja active Active
  • 2008-05-22 KR KR1020107000498A patent/KR101541201B1/ko active Active
  • 2008-05-22 WO PCT/US2008/064488 patent/WO2008156958A2/en not_active Ceased
  • 2008-06-11 TW TW097121772A patent/TWI453817B/zh active

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