Patent ID: 12205843

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

DETAILED DESCRIPTION

Embodiments of the present disclosure generally relate to a vertical ground electrode disposed along a periphery of a substrate support for use in a plasma processing chamber. A substrate support assembly includes the substrate support and a stem. The substrate support has a ceramic body. The ceramic body has an outer vertical wall, a bottom surface and a support surface. The support surface configured to support a substrate thereon. An RF electrode and a heater are disposed within the ceramic body. Additionally, a vertical ground electrode for the plasma RF return path is disposed inside the ceramic body along the outer vertical wall. The vertical ground electrode is suitable for handling high currents. The vertical ground electrode is electrically coupled to the ground electrode in the ceramic body. The stem is attached to the bottom surface of the ceramic body and includes a tubular wall. A ground is disposed through the stem and couples the vertical ground electrode to the plasma RF return path. Advantageously, the vertical ground electrode provides a proper ground along the outer vertical wall of the ceramic body outward the RF electrode and the heater. Braze connection between the stem and the ceramic body allows operation even at temperatures exceeding 650° Celsius. The vertical ground electrode reduces or eliminates parasitic plasma under the heater, thus, reducing the loss of power.

Embodiments herein are illustratively described below in reference to use in a PECVD system configured to process substrates. However, it should be understood that the disclosed subject matter has utility in other system configurations such as etch systems, other chemical vapor deposition systems, physical vapor deposition systems, and other systems in which a substrate is exposed to plasma within a process chamber. It should also be understood that embodiments disclosed herein may be adapted for practice in other process chambers configured to process substrates of various sized and dimensions.

FIG.1is a schematic cross-sectional view of a process chamber100including a substrate support assembly128according to one embodiment described herein. In the example ofFIG.1, the process chamber100is a PECVD chamber. As shown inFIG.1, the process chamber100includes one or more sidewalls102, a bottom104, a gas distribution plate110, and a cover plate112. The sidewalls102, bottom104, and cover plate112, collectively define a processing volume106. The gas distribution plate110and substrate support assembly128are disposed in the processing volume106. The processing volume106is accessed through a sealable slit valve opening108formed through the sidewalls102such that a substrate105may be transferred in and out of the process chamber100. A vacuum pump109is coupled to the chamber100to control the pressure within the processing volume106.

The gas distribution plate110is coupled to the cover plate112at its periphery. A gas source120is coupled to the cover plate112to provide one or more gases through the cover plate112to a plurality of gas passages111formed in the cover plate112. The gases flow through the gas passages111and into the processing volume106toward the substrate receiving surface132.

An RF power source122is coupled to the cover plate112and/or directly to the gas distribution plate110by an RF power feed124to provide RF power to the gas distribution plate110. Various RF frequencies may be used. For example, the frequency may be between about 0.3 MHz and about 200 MHz, such as about 13.56 MHz. An RF return path125couples the substrate support assembly128through the sidewall102to the RF power source122. The RF power source122generates an electric field between the gas distribution plate110and the substrate support assembly128. The electric field forms a plasma from the gases present between the gas distribution plate110and the substrate support assembly128. The RF return path125completes the electrical circuit for the RF energy prevents stray plasma from causing RF arcing due to a voltage differential between the substrate support assembly128and the sidewall102. Thus the RF return path125mitigates arcing which causes process drift, particle contamination and damage to chamber components.

The substrate support assembly128includes a substrate support130and a stem134. The stem134is coupled to a lift system136that is adapted to raise and lower the substrate support assembly128. The substrate support130includes a substrate receiving surface132for supporting the substrate105during processing. Lift pins138are moveably disposed through the substrate support130to move the substrate105to and from the substrate receiving surface132to facilitate substrate transfer. An actuator114is utilized to extend and retract the lift pins138. A ring assembly133may be placed over periphery of the substrate105during processing. The ring assembly133is configured to prevent or reduce unwanted deposition from occurring on surfaces of the substrate support130that are not covered by the substrate105during processing.

The substrate support130may also include heating and/or cooling elements139to maintain the substrate support130and substrate105positioned thereon at a desired temperature. In one embodiment, the heating and/or cooling elements139may be utilized to maintain the temperature of the substrate support130and substrate105disposed thereon during processing to less than about 800° C. or less. In one embodiment, the heating and/or cooling elements139may be used to control the substrate temperature to less than 650° C., such as between 300° C. and about 400° C. The substrate support130is described in further detail inFIGS.2A-2DandFIGS.3A-3Bbelow.

FIGS.2A-2Dare schematic cross-sectional views of the substrate support assembly128ofFIG.1having one embodiment of the substrate support130.FIGS.2A through2Ddepict the simplified assembly, or construction, of the substrate support assembly128over four snapshots in time. The figures illustrate the creation of a ground electrode inside and along the outer periphery of a substrate support130, one embodiment of substrate support130. The creation of the substrate support130will be discussed sequentially fromFIG.2AthroughFIG.2D. However, it should be appreciated that the substrate support130depicted inFIG.2AthroughFIG.2Dcan be formed utilizing a number of different techniques and possibly even different sequences of operations.

FIG.2Aillustrates a body210having a side surface206, a support surface204and a bottom surface205. The view of the body210is flipped upside down inFIG.2A. A RF mesh224is disposed within the body210. A high voltage chucking electrode222and an optional heater226are also disposed within the body210. The RF mesh224, the high voltage chucking electrode222and the heater226each have connections extending individually through the bottom surface205of the body210. The connections provide separate control and power to each of the RF mesh224, the high voltage chucking electrode222and the heater226. The body210is of a ceramic material. The body210may be formed by sintering the ceramic material, such as aluminum nitride (AlN) or aluminum oxide powder or other suitable material. The RF mesh224is embedded in the body210. The RF mesh224has electrical connections extending through the bottom surface205of the body210.

FIG.2Billustrates the body201surrounded on the bottom surface205and the side surface206by a ground electrode228. The ground electrode228may form a continuous cylindrical wall or alternatively a cage like structure around the body210along the side surface206. For example, the cage like structure may be formed by a 3 to 24 pins for the ground electrode228. Each pin of the ground electrode228may be between about 0.5 mm to about 2 mm in diameter. The pins are formed from an RF conductive material such as molybdenum. That is, the ground electrode228may be continuous inside along a radius of the body201or alternately discontinuous inside along the radius. In this manner, the ground electrode228forms a ground path completely around the side surface206of the ESC200. The body201and ground electrode228is surrounded by a cover layer238. A contact pad229may extend through the cover layer238along a mounting surface232on the bottom of an ESC body250for the substrate support130. The contact pad229configured to electrically couple the ground electrode228with an RF gasket or other connection. The cover layer238may be AlN powder or other suitable ceramic material. Alternately, the cover layer238may be another dielectric material suitable for exposure in a plasma processing environment. The ground electrode228extends through the cover layer238at the bottom surface205of the body210to provide electrical connections thereto. A button227may is formed from a RF conductive material. The button227extends between the RF mesh224and the ground electrode228and completes the electric circuit therebetween. The button227may be formed from molybdenum or other suitable metal material. The RF mesh224, embedded in the body201, has electrical connections extending through the cover layer238at the bottom surface205of the body210to provide electrical connections thereto.

FIG.2Cillustrates the cover layer238encapsulating the ground electrode228and the body210to form the ESC130. The cover layer238may be sintered to form an unitary structure with the body210. The ESC130has an ESC body250. The ESC body250has a support surface204, sides260, and a mounting surface232. The mounting surface232corresponds to the bottom surface205of the body210. The mounting surface232has electrical connections corresponding to the ground electrode228extending therethrough. The mounting surface232additionally may have electrical connections for one or more of the RF mesh224, high voltage chucking electrode222and the heater226extending therethrough for proving power and control to the respective RF mesh224, high voltage chucking electrode222and the heater226. The ground electrode228and/or contact pad229coming out at the bottom may be protected by yttrium, aluminum, nickel or a nickel-cobalt ferrous alloy.

FIG.2Dillustrates a stem134attached to the mounting surface232of the ESC body250for forming the substrate support assembly128. The stem280may be attached by any suitable techniques such as gluing, mechanical fasteners, brazing, welding, etc. The respective RF mesh224, high voltage chucking electrode222and the heater226are electrically coupled to wiring routed inside the stem280. The connection for the ground electrode228may be electrically coupled to the stem280. Alternately, the ground electrode228is electrically coupled to wiring or other conductive elements inside the stem280. The electrical connection for the ground electrode228in the stem280will be discussed further below with respect toFIG.4.

FIG.3A-3Bis schematic cross-sectional view of a substrate support330according to another embodiment that may be used to replace the substrate support130ofFIG.1. The substrate support330is formed from a plurality of sheets which may be printed, glued, sintered or formed by one or more suitable techniques, including in a plasma processing chambers such as one or more a deposition chambers, etch chambers, etc.

InFIG.3A, the substrate support330is formed from a plurality of layers. In one embodiment, the substrate support330is formed from a first layer301, a second layer302, a third layer303, a fourth layer304, a fifth layer305, a sixth layer306, a seventh layer307and an eighth layer308. It should be appreciated that the substrate support330may be formed from more or less than eight layers. However, further discussion will be to the embodiment described above wherein the number of layers forming the substrate support330is eight.

The first layer301has a first top surface309, a first bottom surface371and a first side surface361. The second layer302has a second top surface392, a second bottom surface372and a second side surface362. The third layer303has a third top surface393, a third bottom surface373and a third side surface363. The fourth layer304has a fourth top surface394, a fourth bottom surface174and a fourth side surface364. The fifth layer305has a fifth top surface395, a fifth bottom surface375and a fifth side surface365. The sixth layer306has a sixth top surface396, a sixth bottom surface376and a sixth side surface366. The seventh layer307has a seventh top surface397, a seventh bottom surface377and a seventh side surface367. The eighth layer308has an eighth top surface398, an eighth bottom surface378and an eighth side surface368.

A plurality of ground electrical pads310are disposed between the first bottom surface371and the second top surface392proximate the first side surface361. The ground electrical pads310are formed from a conductive material such as a metal. A HV electrode322may additionally be disposed between the first bottom surface371and the second top surface392. A plurality of vias312in the second layer302are disposed below the plurality of ground electrical pads310on the second top surface392of the second layer302proximate the second side surface362. The vias312are filed with conductive material, such as the same conductive material of the pads, and electrically connected to the ground electrical pads310. The number of vias312corresponds to the number of ground electrical pads310. In another example, twice as many vias312are formed in the second layer302as there are ground electrical pads310disposed between the second layer302and the first layer301. It is important to appreciate that each ground electrical pad310has one or more corresponding vias312filled with conductive material attached and electrically coupled thereto.

Additional ground electrical pads310are disposed between the second bottom surface372and the third top surface393proximate the second side surface362. Vias312in the third layer303are disposed below the plurality of ground electrical pads310on the third top surface393proximate the third side surface363. The ground electrical pads310, between the second bottom surface372and the third top surface393, are electrically coupled to the vias312in the second layer302and the vias in the third layer303. An RF mesh324may additionally be disposed between the second bottom surface372and the third top surface393. In one embodiment, the vias312in the second layer302are aligned with the vias312in the third layer. However, the alignment of the vias312in the respective second layer302and third layer303are less important than the electrical conductivity therebetween. In a second embodiment, the vias312in the second layer302are not aligned with the vias312in the third layer303.

Additional ground electrical pads310are disposed between the third bottom surface373and the fourth top surface394proximate the fourth side surface364. Vias312in the fourth layer304are disposed below the plurality of ground electrical pads310on the fourth top surface394proximate the fourth side surface364. The ground electrical pads310, between the third bottom surface373and the fourth top surface394, are electrically coupled to the vias312in the third layer303and the vias312in the fourth layer304. As discussed above, the vias312in the third layer303are electrically coupled to the vias312in the fourth layer304by way of the ground electrical pads310.

Additional ground electrical pads310are disposed between the fourth bottom surface374and the fifth top surface395proximate the fourth side surface364. Vias312in the fifth layer305are disposed below the plurality of ground electrical pads310on the fifth top surface395proximate the fifth side surface365. The ground electrical pads310, between the fourth bottom surface374and the fifth top surface395, are electrically coupled to the vias312in the fourth layer304and the vias312in the fifth layer305. As discussed above, the vias312in the fourth layer304are electrically coupled to the vias312in the fifth layer305by way of the ground electrical pads310.

Additional ground electrical pads310are disposed between the fifth bottom surface375and the sixth top surface396proximate the fifth side surface365. Vias312in the sixth layer306are disposed below the plurality of ground electrical pads310on the sixth top surface396proximate the sixth side surface366. The ground electrical pads310, between the fifth bottom surface375and the sixth top surface396, are electrically coupled to the vias312in the sixth layer306and the vias in the fifth layer305. A heater coil326may optionally be disposed between the fifth bottom surface375and the sixth top surface396. As discussed above, the vias312in the fifth layer305are electrically coupled to the vias312in the sixth layer306by way of the ground electrical pads310.

Additional ground electrical pads310are disposed between the sixth bottom surface376and the seventh top surface397proximate the sixth side surface366. Vias312in the seventh layer307are disposed below the plurality of ground electrical pads310on the seventh top surface397proximate the seventh side surface367. The ground electrical pads310, between the sixth bottom surface376and the seventh top surface397, are electrically coupled to the vias312in the sixth layer306and the vias312in the seventh layer307. As discussed above, the vias312in the sixth layer306are electrically coupled to the vias312in the seventh layer307by way of the ground electrical pads310.

A ground electrode328is disposed between the seventh bottom surface377and the eighth top surface398. The ground electrode328extends to the eighth side surface368. The eighth layer308has a center399. The ground electrode328extends through the center399for making electrical connections thereto. The vias312may additionally extend through the eighth layer308. A ground pad329may be electrically coupled to the ground electrode328through the via312. The ground pad329configured to electrically couple the ground electrode328with an RF gasket or other connection. The HV electrode322, RF mesh324, and heater coil326have electrical connections extending through the center399for providing power and control to the respective HV electrode322, RF mesh324, and heater386. The ground electrode328and/or ground pad329coming out at the bottom may be protected by yttrium, aluminum, nickel or a nickel-cobalt ferrous alloy.

FIG.3Billustrates the ESC330formed from the assembly of the first layer301through eighth layer308discussed above. With the arrangement of electrically coupled vias312and ground electrical pads310disposed within the ESC330adjacent the side surface360between the first layer301and the eighth layer308, each via312of the plurality of vias312and each ground electrical pad310form a ground path through the ESC330adjacent the side surface360. The vias312are substantially orthogonal a substrate support surface350of the ESC330. The vias312and ground electrical pads310to the disposed within the body of the ESC330in a cylindrical pattern. The vias312and ground electrical pads310may form a continuous cylindrical wall or alternatively a cage like structure. For example, the cage like structure may be formed by a 3 to 24 pin like structure for the vias312. Each via312may be between about 0.5 mm to about 2 mm in diameter. The vias may be metal filled forming a continuous conductive pathway. Alternatively, the vias312may be continuous along a radius of the ESC330. In this manner, the vias312form a ground path completely around the side surface360of the ESC330.

The electrical coupling of the ground electrode228/328to the stem will now be discussed with respect toFIG.4.FIG.4is schematic perspective view of the substrate support assembly128ofFIG.1according to one embodiment. The ESC330ofFIGS.3A-3Bis equally suitable for the substrate support assembly128and the electrical ground connection discussed with respect toFIG.4. The stem134may be attached to the ESC130/330by a number of suitable techniques for forming the substrate support assembly128. For example, the stem134may be welded, chemically bonded, or mechanically bonded to the ESC130/330. In one embodiment, the stem134is diffusion bonded to the ESC130/330.

The stem134has a hollow interior434. A metal ground tube442is disposed within the hollow interior434of the stem134. The metal ground tube442is a circular cylinder of metal. The metal ground tube442may be formed from Mo, Au or Ag coated moly or nickel-cobalt ferrous alloy, or other suitable material. The metal ground tube442has an interior area444. The interior area444is configured to provide space for electrical connections to the ESC130to pass therethrough the metal ground tube442. A RF grounding coax return (Shown inFIGS.2A through2D and3B) is provided for the ground mesh228/328through the metal ground tube441. The metal ground tube442has a plurality of ground tube connectors420. The ground tube connectors420are configured to mate with a respective mesh connector410as shown by arrow415. The ground tube connectors420may be tabs or protrusions in the metal ground tube442. The ground tube connectors420may fit into the respective mesh connector410to provide an electrical connection with the ground mesh228/238for completing the ground path. In one embodiment, the ground electrode228is brazed at the ground tube connectors420for completing the ground return path disposed within the sides260/360of the ESC130/330. Thus, a RF shield is produced at the bottom and edge of substrate support130by a shielding effect wherein RF will be present on wires inside shaft, the heater and the RF mesh.

FIG.5is a schematic cross-sectional view of a processing chamber500including the substrate support assembly128according to second embodiment. The processing chamber500has a body501. The body501has sidewalls502, a bottom504and a cover plate512. The sidewalls502, a bottom504and a cover plate512define an interior volume506of the processing chamber500. Disposed within interior volume506of the processing chamber500is the substrate support assembly128. A plasma142may form in the interior volume and be maintained by RF energy supplied through the processing chamber500.

The substrate support assembly128has an ESC530and a metal ground tube560. A chucking electrode528is disposed within the ESC530. A metal coating554is disposed on an outer surface of the substrate support assembly128. The metal coating554may be formed from molybdenum, aluminum, copper or other suitably conductive material. The metal coating554is electrically coupled to the RF ground loop.

The metal ground tube560may be formed from molybdenum, aluminum, copper or other suitably conductive material. The metal ground tube560is electrically coupled to the RF ground loop. One or more RF gaskets550,552may be disposed between the metal ground tube560and the chamber components which are part of the RF ground path. The RF gaskets550,552are conductive to RF energy and transmit RF energy therethrough for forming the RF ground circuit. The RF gasket550,552can be formed from nickel, copper, aluminum, molybdenum or other suitable material. The RF gaskets550are disposed between the metal ground tube560and the sidewall502or cover plate512of the processing chamber500. Additionally, RF gaskets552may be disposed between the metal ground tube560and the metal coating554for coupling the RF energy therebetween. Advantageously, the RF ground return path can be made short for reducing the resistance in the ground path and reducing the voltage drop between various chamber components to prevent arcing.

FIG.6is a partial schematic cross-sectional view of a processing chamber600including the substrate support assembly128according to third embodiment. The processing chamber600has a body601. The body has sidewalls602, a bottom604and a showerhead612. The sidewalls602, bottom604and showerhead612define an interior volume606. The substrate support assembly128is disposed within the interior volume606. A RF generator680is coupled an electrode682in the showerhead612. The RF generator680has a RF return path688for completing the RF circuit when plasma is present.

The substrate support assembly128has a heater626, a HV chucking mesh622, and a RF mesh624disposed therein. The substrate support assembly128has an exterior surface629. A metal coating684is disposed on the exterior surface629of the substrate support assembly128. The metal coating684is formed from nickel, copper, aluminum, molybdenum or other suitable material. The metal coating684is part of the RF return path688and completes the ground for the RF when the RF generator680is powered on. A protective coating632may be disposed on the metal coating684to protect the metal coating684from corrosion and help maintain the conductivity of the metal coating684. The protective coating632may be formed from yttria, AlN, Al2O3or other suitable material. The protective coating632maintains the connection for the RF ground path for the substrate support assembly128. Advantageously, the RF ground path for maintaining the plasma can be maintained and provide a long service life for the substrate support assembly128.

FIG.7is a method700for forming an ESC. The method700begins at operation710by sintering an AlN body having a heater, an RF electrode mesh and an HV ESC electrode mesh. At operation720, a ground electrode mesh is disposed along one or more outer surfaces of the sintered AlN body. At operation730, the ground electrode mesh and the sintered body are encased in an aluminum powder to form an ESC body. At operation740, the ESC body is sintered to form the ESC.

FIG.8is another method800for forming an ESC. The method800begins at operation810by printing a HV ESC electrode on a top surface of a first sheet of AlN. At operation830, ground plane electrode is printed on a top surface of a second sheet of ceramic. At operation840, a plurality of second vias is formed in the second sheet of ceramic and connected to the ground plane electrode. At operation850, one or more heater electrodes is printed on a top surface of a third sheet of ceramic. At operation860, a plurality of third vias is formed in the third sheet of ceramic, the third vias vertically aligned with the second vias. At operation870, a ground mesh is printed on a top surface of a fourth sheet of ceramic. The ground mesh is electrically coupled through the vias to the ground plane electrode. At operation880, a plurality of fourth vias is formed in the fourth sheet of ceramic, the fourth vias vertically aligned with the second vias. At operation890, a fifth sheet of ceramic is placed on the top surface of the first sheet to for the ESC body.

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