Abstract: An electrostatic chuck for a substrate processing system is provided and includes a baseplate, an intermediate layer disposed on the baseplate, and a top plate. The top plate is bonded to the baseplate via the intermediate layer and is configured to electrostatically clamp to a substrate. The top plate includes a monopolar clamping electrode and seals. The monopolar clamping electrode includes a groove opening pattern with coolant gas groove opening sets. The seals separate coolant gas zones. The coolant gas zones include four or more coolant gas zones. Each of the coolant gas zones includes distinct coolant gas groove sets. The top plate includes the distinct coolant gas groove sets. Each of the distinct coolant gas groove sets has one or more coolant gas supply holes and corresponds to a respective one of the coolant gas groove opening sets.

Abstract: A radio frequency (RF) source may be used to generate a capacitively coupled plasma to perform a plasma-based process on a substrate in a plasma processing chamber. A controller may cause the RF source and a switching element to route an RF signal to electrodes in the pedestal that generate the plasma in the processing chamber as part of a recipe performed on a substrate during etch or deposition processes. Between processes, the controller may cause the same RF source to generate a second RF signal that is instead routed by the switching element to inductive coils to generate an inductively coupled plasma for a cleaning process to remove film deposits on the interior of the plasma processing chamber.

Abstract: A sample holder includes an insulating substrate, a heat element, a support member, and a bond. The insulating substrate is a ceramic member having a first surface and a second surface opposite to the first surface. The heat element is on the second surface of the insulating substrate. The second surface of the insulating substrate includes a first portion where the heat element is located, a second portion surrounding the first portion, and a groove between the first portion and the second portion. A surface roughness of the first portion is greater than a surface roughness of the second portion.

Abstract: The electrostatic chuck includes an insulating substrate having a placement surface on which a suction target object is placed and an opposite surface provided on an opposite side to the placement surface; and a gas hole penetrating from the opposite surface to the placement surface. The gas hole has a first hole portion extending from the opposite surface toward the placement surface, a second hole portion extending from the placement surface toward the opposite surface, and a third hole portion provided between the first hole portion and the second hole portion and formed to communicate the first hole portion and the second hole portion each other. The first hole portion is provided not to overlap with the second hole portion in a plan view.

Abstract: The present disclosure generally relates to a substrate support that includes a body having a substrate receiving surface, the body comprising a dielectric material. The body also includes a first foil embedded in the body below the substrate receiving surface. The body also includes an electrically conductive mesh embedded in the body below the first foil. The body also includes a center tap structure formed in a bottom surface of the body that is in electrical communication with the mesh.

Abstract: Provided is a plasma processing apparatus capable of obtaining desired etch profiles and preventing the degradation of yield rates due to the adhesion of particles, and equipped with a processing chamber in which a sample is plasma-treated; a radio-frequency power source for supplying radio-frequency power used to generate plasma; a sample stage which is provided with electrodes for electrostatically adsorbing the sample and on which the sample is mounted; and a DC power supply for applying DC voltages to the electrodes, the apparatus being further equipped with a control apparatus for controlling the DC power supply so as to apply such DC voltages as to decrease the absolute value of the potential of the sample in the absence of the plasma.

Abstract: An apparatus may include a resonator chamber, arranged in a vacuum enclosure; an RF electrode assembly, arranged within the vacuum enclosure; and a resonator coil, disposed within the resonator chamber, the resonator coil having a high voltage end, directly connected to at least one RF electrode of the RF electrode assembly.

Abstract: An apparatus comprises a flexible membrane for use with a carrier head of a substrate chemical mechanical polishing apparatus. The membrane comprises an outer surface providing a substrate receiving surface, wherein the outer surface has a central portion and an edge portion surrounding the central portion, wherein the central portion has a first surface roughness and the edge portion has a second surface roughness, the first surface roughness being greater than the second surface roughness.

Abstract: A plasma processing method is disclosed that includes (a) placing a substrate on an electrostatic chuck at a first temperature, the electrostatic chuck being disposed in a plasma processing chamber; (b) electrostatically attracting the substrate to the electrostatic chuck; (c) starting supply of a heat transfer gas between the substrate and the electrostatic chuck; (d) detecting a flow rate of the heat transfer gas or a pressure between the substrate and the electrostatic chuck; (e) determining whether the flow rate or the pressure exceeds a predetermined threshold value; (f) raising the temperature of the electrostatic chuck until the temperature of the electrostatic chuck becomes a second temperature, the second temperature being higher than the first temperature; and (g) generating plasma in the plasma processing chamber.

Abstract: The described implementations relate a Passive Optical Network (PON). In one implementation, the PON includes an Optical Network Unit (ONU) that has at least one transmitter subsystem component and an associated optical transmitter. The at least one transmitter subsystem component may be configured to be in an enabled state during a timeslot period assigned to the ONU for transmitting an upstream data burst and a disabled state after the timeslot ends.

Abstract: The invention relates to a tracking reference, comprising: a reference array (1) featuring a positionally fixed arrangement of at least two tracking markers (3); and an interface (4A) for detachably coupling the reference array (1) to a base member (2), wherein the interface (4A) comprises at least one supporting surface (5) for contacting the base member (2), wherein the interface (4A) comprises magnetic means (6) which generate a force at the reference array, wherein the force (F) is directed away from the supporting surface (5).

Abstract: An electrostatic chuck including a clamping layer having a first clamping electrode and a second clamping electrode is disclosed. A first clamping electrode defining a first clamping zone and a second clamping zone is provided. The first clamping zone and the second clamping zone are separated by a first gap and are electrically connected by at least one electrical connection extending across the first gap. A second clamping electrode disposed radially outward from the first clamping electrode. The second clamping electrode defining a third clamping zone and a fourth clamping zone that are separated by a second gap. The third clamping zone and the fourth clamping zone are electrically connected by at least one electrical connection extending across the second gap. Plasma processing apparatuses and systems incorporating the electrostatic chuck are also provided.

Abstract: Embodiments of substrate supports are provided herein. In some embodiments, a substrate support for use in a chemical vapor deposition (CVD) chamber includes: a pedestal to support a substrate, wherein the pedestal includes a dielectric plate coupled to a pedestal body; a rotary union coupled to the pedestal, wherein the rotary union includes a stationary housing disposed about a rotor; a drive assembly coupled to the rotary union; a coolant union coupled to the rotary union and having a coolant inlet fluidly coupled to coolant channels disposed in the pedestal via a coolant line; an RF rotary joint coupled to the coolant union and having an RF connector configured to couple the pedestal to an RF bias power source; and an RF conduit that extends from the RF connector to the pedestal through a central opening of the pedestal body to provide RF bias to the pedestal.

Abstract: Some implementations described herein provide techniques and apparatuses for a semiconductor processing tool including an electrostatic chuck having a voltage-regulation system to regulate an electrical potential throughout regions of a semiconductor substrate positioned above the electrostatic chuck. The voltage-regulation system may determine that an electrical potential within a region of the semiconductor substrate does not satisfy a threshold. The voltage-regulation system may, based on determining that the electrical potential throughout the region does not satisfy the threshold, position one or more electrically-conductive pins within the region. While positioned within the region, the one or more electrically-conductive pins may change the electrical potential of the region.

Abstract: A wafer placement table includes a ceramic substrate that has a wafer placement surface, a first electrode that is embedded in the ceramic substrate, a first power supply terminal that is inserted from a surface of the ceramic substrate opposite the wafer placement surface toward the first electrode, a first joint that joins the first electrode and the first power supply terminal to each other and a second electrode that is disposed between the wafer placement surface and the first electrode in the ceramic substrate. A linear portion that extends in the ceramic substrate from a position on the first electrode opposite the first joint to the wafer placement surface is composed of material of the ceramic substrate.

Abstract: A plasma processing apparatus includes a chamber; a substrate support disposed in the chamber and including a lower electrode; an upper electrode disposed above the substrate support; an RF source that supplies an RF power to the lower electrode or the upper electrode, the RF power having a plurality of power levels during a first sequence in a repeating time period, the plurality of power levels including a first power level during a first state and a second state, and a second power level during a third state and a fourth state; and a DC source that applies a DC voltage to the lower electrode, the DC voltage having a plurality of voltage levels during the first sequence in the repeating time period.

Abstract: A chucking system reduces differences in chucking forces that are applied by two electrodes of an electrostatic chuck, to a substrate disposed atop the chuck. Initial chucking voltages are applied to each of two electrodes, and an initial current provided to at least a first electrode of the two electrodes is measured. A process is initiated that affects a DC voltage of the substrate, then a modified current provided to at least the first electrode is measured. A modified chucking voltage for a selected one of the two electrodes is determined that will reduce chucking force imbalance across the substrate based at least on the initial current and the modified current. The modified chucking voltage is then provided to the selected one of the two electrodes.

Abstract: A mounting system includes a magnet core arranged for positioning inside a magnet coil. The magnet core includes a cylindrical, elongate receiving region with a central axis, a rapid-mounting mandrel arranged for insertion into the cylindrical, elongate receiving region, and a discoid workpiece driver, detachably fastened to the rapid-mounting mandrel and extending normal to the central axis. A one of the magnet core or the rapid-mounting mandrel includes a rapid-mounting device for mounting the rapid-mounting mandrel in the magnet core. Example embodiments may includes the rapid-mounting device integrated into the magnet core or integrated into the rapid-mounting mandrel.

Abstract: A body of an electrostatic chuck comprises mesas disposed on a polished surface of the body. Each of the mesas comprises an adhesion layer disposed on the polished surface of the body, a transition layer disposed over the adhesion layer, and a coating layer disposed over the transition layer. The coating layer has a hardness of at least 14 GPa. The body further comprises a sidewall coating disposed over a sidewall of the body. A method for preparing the body comprises polishing the surface of the body and cleaning the polished surface. The method further comprises depositing the mesas by depositing the adhesion layer on the body, the transition layer over the adhesion layer, and the coating layer over the transition layer. Further, the method includes, polishing the mesas.

Abstract: Exemplary support assemblies may include an electrostatic chuck body defining a support surface that defines a substrate seat. The assemblies may include a support stem coupled with the chuck body. The assemblies may include a heater embedded within the chuck body. The assemblies may include a first bipolar electrode embedded within the electrostatic chuck body between the heater and support surface. The assemblies may include a second bipolar electrode embedded within the chuck body between the heater and support surface. Peripheral edges of one or both of the first and second bipolar electrodes may extend beyond an outer periphery of the seat. The assemblies may include an RF power supply coupled with the first and second bipolar electrodes. The assemblies may include a first floating DC power supply coupled with the first bipolar electrode. The assemblies may include a second floating DC power supply coupled with the second bipolar electrode.

Abstract: A method of constructing an E-puck includes forming at least one trench into a lower substrate, depositing an electrode material onto the lower substrate and into the at least one trench, removing excess electrode material from the lower substrate to leave the electrode material within the at least one trench to form an electrode, and forming a dielectric on the lower substrate and the electrode. The electrode is between the lower substrate and the upper substrate. Forming the at least one trench into the lower substrate forms at least one standoff portion adjacent to the at least one trench and the at least one standoff portion reduces dishing of the electrode material during removal of the excess electrode material from the lower substrate.

Abstract: A substrate supporting member capable of controlling the flow of charges on a substrate by controlling ground resistance values of a guide pin and a support pin using a variable resistor, and a substrate treating apparatus including the same are provided. The substrate supporting member includes the body; a support pin installed on the body and for supporting the substrate; a guide pin installed on the body and for supporting the substrate; and a charge control device for controlling a charge around the substrate by controlling an electrical connection between the support pin and a first resistor and an electrical connection between the guide pin and a second resistor.

Abstract: A magnetic base for an electric power tool, in particular for a magnetic core drilling machine. The magnetic base having a base body that has a contact surface for contacting a workpiece to be machined, at least one first permanent magnet and at least one second permanent magnet arranged in the base body, the at least one and second permanent magnet having magnetic forces that interact to form a resulting holding force. The at least one first permanent magnet and the at least one second permanent magnet are supported in the base body and rotatable around its own rotation axis between a first position, in which the resulting holding force of the magnetic base is maximized, and a second position, in which the resulting holding force of the magnetic base is minimized.

Abstract: A method for adjusting a contact position of lift pins in a substrate placement mechanism is provided. The substrate placement mechanism includes a substrate placement table and a substrate lifting mechanism having lift pins and a driving mechanism, wherein the contact position of the lift pins is a height position where tip ends of the lift pins get in contact with the substrate. The method comprises creating torque waveforms, for a plurality of voltages, indicating temporal changes of a torque of the motor while moving the tip ends of the lift; obtaining from the plurality of torque waveforms a contact point when the lift pins get in contact with the substrate and calculating the contact position from the contact point and a speed of the motor; determining whether the contact position is within an appropriate range; and automatically adjusting the contact position when the contact position is not within the appropriate range.

Abstract: A member for semiconductor manufacturing apparatus, includes: a ceramic plate having a wafer placement surface; a plug receiving hole formed in a surface of the ceramic plate opposite to the wafer placement surface; a gas outlet port extending through a bottom wall of the plug receiving hole; a plug received in the plug receiving hole; and a gas flow path disposed inside the plug to be continuous with the gas outlet port, wherein a stepped portion is disposed on a side surface of the plug or an inner surface of the plug receiving hole, the plug receiving hole and the plug are in contact with each other in an area deeper than the stepped portion, a gap is formed between the plug receiving hole and the plug in an area shallower than the stepped portion, and a plug support member made of an adhesive material is formed in the gap.

Abstract: A wafer chuck assembly includes a puck, a shaft and a base. The puck includes an electrically insulating material that defines a top surface of the puck; a plurality of electrodes are embedded within the electrically insulating material. The puck also includes an inner puck element that forms one or more channels for a heat exchange fluid, the inner puck element being in thermal communication with the electrically insulating material, and an electrically conductive plate disposed proximate to the inner puck element. The shaft includes an electrically conductive shaft housing that is electrically coupled with the plate, and a plurality of connectors, including electrical connectors for the electrodes. The base includes an electrically conductive base housing that is electrically coupled with the shaft housing, and an electrically insulating terminal block disposed within the base housing, the plurality of connectors passing through the terminal block.

Abstract: Methods and systems of detection of wafer de-chucking in a semiconductor processing chamber are disclosed. Methods and systems of interdiction are also disclosed to prevent hardware and wafer damage during semiconductor fabrication if and when de-chucking is detected. In one embodiment, a de-chucking detection method is based on measuring change in imaginary impedance of a plasma circuit, along with measuring one or both of reflected RF power and arc count. In another embodiment, a possibility of imminent de-chucking is detected even before complete de-chucking occurs by analyzing the signature change in imaginary impedance.

Abstract: Implementations of the present disclosure generally relate to an improved substrate support pedestal assembly. In one implementation, the substrate support pedestal assembly includes a shaft. The substrate support pedestal assembly further includes a substrate support pedestal, mechanically coupled to the shaft. The substrate support pedestal comprises substrate support plate coated on a top surface with a ceramic material.

Abstract: Described are apparatus and methods for processing a semiconductor wafer so that the wafer remains in place during processing. The wafer is subjected to a pressure differential between the top surface and bottom surface so that sufficient force prevents the wafer from moving during processing, the pressure differential generated by applying a decreased pressure to the back side of the wafer.

Abstract: An electrostatic chuck for a substrate processing system includes a monolithic body made of ceramic. A plurality of first electrodes are arranged in the monolithic body adjacent to a top surface of the monolithic body and that are configured to selectively receive a chucking signal. A gas channel is formed in the monolithic body and is configured to supply back side gas to the top surface. Coolant channels are formed in the monolithic body and are configured to receive fluid to control a temperature of the monolithic body.

Abstract: A susceptor can include a generally circular shape and may include an inner and outer susceptor. The outer susceptor can include a support region having one or more support mechanisms as well as a channel region extending from the region boundary to an outer radial boundary radially inward of an outer edge of the susceptor, the channel region can include a plurality of channels extending radially from the region boundary to the outer radial boundary. The inner susceptor can include a second plurality of channels extending from the inner radial boundary to an edge of the inner susceptor.

Abstract: Electrostatic chucks (ESCs) for plasma processing chambers, and methods of fabricating ESCs, are described. In an example, a substrate support assembly includes a ceramic top plate having a top surface with a processing region. One or more electrodes is within the ceramic top plate. A plurality of mesas is within the processing region and on the top surface of the ceramic plate or vertically over an edge of one of the one or more electrodes.

Abstract: A Johnsen-Rahbek force type electrostatic chuck including: a metal substrate; an electrode for electrostatic attraction provided on the metal substrate with an insulating layer interposed between the metal substrate and the electrode for electrostatic attraction; and a dielectric layer constituting an electrostatic attraction surface in contact with a workpiece. The dielectric layer includes a ceramic spray coating and a sealing component with which pores of the ceramic spray coating are filled, and the sealing component contains a metal organic salt containing a rare earth element.

Abstract: Embodiments of the present disclosure relate to a system for pulsed direct-current (DC) biasing and clamping a substrate. In one embodiment, the system includes a plasma chamber having an electrostatic chuck (ESC) for supporting a substrate. An electrode is embedded in the ESC and is electrically coupled to a biasing and clamping network. The biasing and clamping network includes at least a shaped DC pulse voltage source and a clamping network. The clamping network includes a DC source and a diode, and a resistor. The shaped DC pulse voltage source and the clamping network are connected in parallel. The biasing and clamping network automatically maintains a substantially constant clamping voltage, which is a voltage drop across the electrode and the substrate when the substrate is biased with pulsed DC voltage, leading to improved clamping of the substrate.

Abstract: An electrostatic chuck is described that has radio frequency coupling suitable for use in high power plasma environments. In some examples, the chuck includes a base plate, a top plate, a first electrode in the top plate proximate the top surface of the top plate to electrostatically grip a workpiece, and a second electrode in the top plate spaced apart from the first electrode, the first and second electrodes being coupled to a power supply to electrostatically charge the first electrode.

Abstract: An electrostatic chuck for a substrate processing system is provided and includes a baseplate, an intermediate layer disposed on the baseplate, and a top plate. The top plate is bonded to the baseplate via the intermediate layer and is configured to electrostatically clamp to a substrate. The top plate includes a monopolar clamping electrode and seals. The monopolar clamping electrode includes a groove opening pattern with coolant gas groove opening sets. The seals separate coolant gas zones. The coolant gas zones include four or more coolant gas zones. Each of the coolant gas zones includes distinct coolant gas groove sets. The top plate includes the distinct coolant gas groove sets. Each of the distinct coolant gas groove sets has one or more coolant gas supply holes and corresponds to a respective one of the coolant gas groove opening sets.

Abstract: A stage to be disposed in a chamber of a plasma processing apparatus is provided. The stage includes a chuck with a mounting portion for a substrate and a first hole through the mounting portion. The stage includes a base disposed beneath the chuck, the base including a second hole through the base, and the second hole communicating with the first hole. The base includes a first cylindrical liner disposed in the second hole, the first cylindrical liner having a relative permittivity of 5 or less.

Abstract: An attachment and detachment device that excels in responsiveness to attachment and detachment of a workpiece even when the workpiece is thin while utilizing an electrostatic chuck method is provided. The attachment and detachment device that enables suction and separation of a workpiece includes a machinable ceramic layer, an adhesion activating layer provided on the machinable ceramic layer, an electrode layer provided on the adhesion activating layer, and a dielectric layer provided on the electrode layer, wherein the electrode layer is covered with the adhesion activating layer and the dielectric layer, and the dielectric layer has a volume resistivity of 109 to 1012 ?·cm.

Abstract: An electrostatic chuck includes a base body having a placement surface on which a suction target object is placed, and an electrode embedded in the base body. The base body is provided with a groove that opens to the placement surface-side and does not reach the electrode. Aloes-resistance region made of ceramics and a high-resistance region made of ceramics having a volume resistivity higher than the low-resistance region are sequentially arranged from a side close to the groove between a bottom surface of the groove and the electrode, in a thickness direction of the base body.

Abstract: An electrostatic adsorption member includes a dielectric member having a first surface and a second surface opposite to the first surface and formed with a through-hole penetrating from the first surface to the second surface, and a porous body provided in the through-hole and having a third surface flush with the first surface. The through-hole has a first opening apart from the first surface by a first distance in a first direction perpendicular to the first surface, and a second opening apart from the first surface by a second distance larger than the first distance in the first direction. In a plan view from the first direction, at least a portion of the first opening is inside the second opening, and the porous body has a first portion located inside the first opening, and a second portion connected to the first portion and located outside the first opening.

Abstract: The plasma processing apparatus includes a chamber body, a stage, a gas supply mechanism, a DC power supply, a radio-frequency power supply, and a controller. The gas supply is configured to supply a heat transfer gas to the upper surface of the electrostatic chuck. The controller is configured to control the DC power supply. The controller controls the DC power supply to apply, to the electrostatic chuck, a voltage derived by combining an output of a first function that outputs a smaller value as the absolute value of a self-bias voltage generated according to the plasma becomes larger and an output of a second function that outputs a larger value as the pressure of the heat transfer gas supplied to the upper surface of the electrostatic chuck by the gas supply increases.

Abstract: Process chamber, high voltage measurement systems and methods for monitoring the output of a high voltage power supply are described. The output of the high voltage power supply is converted using a transducer and measured with high accuracy. A high voltage measurement system compares the converted value with a threshold criterion and actuates an interlock if readings are outside the threshold.

Abstract: An electrostatic chuck including a clamping layer having a first clamping electrode and a second clamping electrode is disclosed. A first clamping electrode defining a first clamping zone and a second clamping zone is provided. The first clamping zone and the second clamping zone are separated by a first gap and are electrically connected by at least one electrical connection extending across the first gap. A second clamping electrode disposed radially outward from the first clamping electrode. The second clamping electrode defining a third clamping zone and a fourth clamping zone that are separated by a second gap. The third clamping zone and the fourth clamping zone are electrically connected by at least one electrical connection extending across the second gap. Plasma processing apparatuses and systems incorporating the electrostatic chuck are also provided.

Abstract: Described are electrostatic chucks designed for use in supporting a workpiece during a workpiece processing step, the electrostatic chuck including a gas flow system.

Abstract: A method includes: positioning a wafer on an electrostatic chuck of an apparatus; and securing the wafer to the electrostatic chuck by: securing a first wafer region of the wafer to a first chuck region of the electrostatic chuck by applying a first voltage at a first time. The method further includes securing a second wafer region of the wafer to a second chuck region of the electrostatic chuck by applying a second voltage at a second time different from the first time; and processing the wafer by the apparatus while the wafer is secured to the electrostatic chuck.

Abstract: Embodiments of the present disclosure generally relate to a pedestal for increasing temperature uniformity in a substrate supported thereon. The pedestal comprises a body having a heater embedded therein. The body comprises a patterned surface that includes a first region having a first plurality of posts extending from a base surface of the body at a first height, and a second region surrounding the central region having a second plurality of posts extending from the base surface at a second height that is greater than the first height, wherein an upper surface of each of the first plurality of posts and the second plurality of posts are substantially coplanar and define a substrate receiving surface.

Abstract: A multi-zone heater with a plurality of thermocouples such that different heater zones can be monitored for temperature independently. The independent thermocouples may have their leads routed out from the shaft of the heater in a channel that is closed with a joining process that results in hermetic seal adapted to withstand both the interior atmosphere of the shaft and the process chemicals in the process chamber. The thermocouple and its leads may be enclosed with a joining process in which a channel cover is brazed to the heater plate with aluminum.

Abstract: A semiconductor substrate processing apparatus includes a vacuum chamber having a processing zone in which a semiconductor substrate may be processed, a process gas source in fluid communication with the vacuum chamber for supplying a process gas into the vacuum chamber, a showerhead module through which process gas from the process gas source is supplied to the processing zone of the vacuum chamber, and a substrate pedestal module.

Abstract: A holding device includes a ceramic member and a base member joined together via a joining portion. When a second direction is perpendicular to a first direction and a third direction is perpendicular to the first and second directions, the joining portion includes a first joining part which extends through the joining portion in the second direction, as viewed in the first direction, and whose thickness in the first direction is uniform in an arbitrary cross section perpendicular to the second direction and in an arbitrary cross section perpendicular to the third direction, and at least one second joining part which is located between the first joining part and one end of the joining portion in the third direction and whose thickness in the first direction increases from the first joining part side toward the end of the joining portion in an arbitrary cross section perpendicular to the second direction.

Abstract: A member for a semiconductor manufacturing apparatus includes a ceramic plate having an upper surface serving as a wafer mounting surface and incorporating an electrode, a ceramic dense plug disposed adjacent to a lower surface side of the ceramic plate and ceramic-bonded to the ceramic plate by a ring-shaped joint portion, a metal cooling plate joined to the lower surface of the ceramic plate in a portion other than the ring-shaped joint portion, and a gas flow channel. The gas flow channel includes a gas discharge hole that passes completely through the ceramic plate in the thickness direction of the ceramic plate and an internal gas flow channel that passes from the upper surface to the lower surface of the dense plug while winding through the dense plug. The gas flow channel passes inside of an inner periphery of the joint portion.