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.

Abstract: A composite sintered body includes a base material (i.e., a main body) using ceramics as a main material and an electrode disposed inside the main body or on a surface thereof. The electrode contains WC and TiN. It is thereby possible to reduce the difference in thermal expansion coefficient between the electrode and the main body while suppressing an increase in the resistivity of the electrode. As a result, it is possible to suppress any damage such as a crack, a breakage, or the like of the main body, which is caused by the difference in the thermal expansion coefficient.

Abstract: Provided are an electrostatic chuck, which is manufactured to be reusable by removing a part of a dielectric layer except for a DC electrode and a heater electrode and depositing a new dielectric layer thereon, and a method for manufacturing the electrostatic chuck, and a substrate processing system including the electrostatic chuck. The method for manufacturing the electrostatic chuck includes, after using an electrostatic chuck, removing a portion of an upper part of a first dielectric layer of the electrostatic chuck where an electrode is not formed, depositing a second dielectric layer on the first dielectric layer from which the portion of the upper part has been removed, and patterning the second dielectric layer to enable reuse of the electrostatic chuck.

Abstract: A temperature changing method includes changing a pressure of a gas supplied from a gas supply to a gap between the substrate and an electrostatic chuck from a first pressure to a second pressure being lower than the first pressure, changing a voltage applied to the electrostatic chuck from a first voltage to a second voltage being lower than the first voltage, changing a temperature of the electrostatic chuck from a first temperature to a second temperature, electrostatically attracting the substrate by the electrostatic chuck for a time in a state where the gas pressure is the second pressure and the voltage is the second voltage, changing the gas pressure from the second pressure to a third pressure being lower than the first pressure and higher than the second pressure, and changing the voltage from the second voltage to a third voltage being higher than the second voltage.

Abstract: A method of detecting plasma asymmetry in a radio frequency plasma processing system, the method including providing a radio frequency power to a reaction chamber having an approximate chamber symmetry axis and receiving from a plurality of broadband electromagnetic sensors a radio frequency signal. The method also including processing the radio frequency signals using Fourier analysis and determining based on the Fourier analysis of the radio frequency signals that a plasma asymmetry has occurred within the reaction chamber.

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 sample releasing method for releasing a sample subjected to plasma processing from a sample stage on which the sample is electrostatically attracted by applying DC voltage to an electrostatic chuck electrode, and the method includes: moving the sample subjected to the plasma processing upward above the sample stage; and after moving the sample, controlling the DC voltage such that an electric potential of the sample is to be smaller.

Abstract: The present invention resides in the unifying idea of synchronizing a positive voltage pulse supplied to an electrically conductive or ferromagnetic tube and a exciting negative voltage pulse on a hollow cathode induced on the background of a high-frequency capacitive discharge. In one embodiment, the invention relates to a method of generating low-temperature plasma in a vacuum chamber comprising a hollow cathode and an electrode, the method comprising the step of igniting the pulsed DC discharge in the hollow cathode wherein the positive voltage pulse at least partially overlaps with the negative voltage pulse, and the positive voltage pulse at least partially overlaps with the negative voltage pulse on the hollow cathode. In another embodiment, the present invention relates to a method of coating the inner walls of hollow tubes which utilizes the above-mentioned low-temperature plasma generation process.

Abstract: A sample holder according to the disclosure includes: an insulating base body in plate form; an electrically conducting member disposed on a lower face of the insulating base body; a lead pin joined to the electrically conducting member so as to extend downwardly from the insulating base body; a tubular member joined to the lower face of the insulating base body so as to surround the lead pin; a first member which is located in an interior of the tubular member and covers a junction between the electrically conducting member and the lead pin, the first member being in a gel form; and a second member which covers the first member and is filled in the interior.

Abstract: A substrate processing apparatus includes a stage on which a substrate is placed, wherein the stage includes a first plate, a first temperature adjustment mechanism configured to control a temperature of the first plate, a second plate provided below the first plate, a second temperature adjustment mechanism configured to control a temperature of the second plate, and a fastening member configured to fasten the first plate and the second plate.

Abstract: A method reduces differences in chucking forces that are applied by two electrodes of an electrostatic chuck, to a substrate disposed atop the chuck. The method includes providing initial chucking voltages to each of the two electrodes, and measuring an initial current provided to at least a first electrode of the two electrodes. The method further includes initiating a process that affects a DC voltage of the substrate, then measuring a modified current provided to at least the first electrode, and determining, based at least on the initial current and the modified current, a modified chucking voltage for a selected one of the two electrodes, that will reduce chucking force imbalance across the substrate. The method also includes providing the modified chucking voltage to the selected one of the two electrodes.

Abstract: Aspects of the present disclosure relate generally to pedestals, components thereof, and methods of using the same for substrate processing chambers. In one implementation, a pedestal for disposition in a substrate processing chamber includes a body. The body includes a support surface. The body also includes a stepped surface that protrudes upwards from the support surface. The stepped surface is disposed about the support surface to surround the support surface. The stepped surface defines an edge ring such that the edge ring is integrated with the pedestal to form the body that is monolithic. The pedestal also includes an electrode disposed in the body, and one or more heaters disposed in the body.

Abstract: An electrostatic chuck fixes a substrate and includes a first area and a second area adjacent to the first area. The electrostatic chuck includes a first electrode portion disposed in the first area and a second electrode portion disposed in the second area. The first electrode portion has a first width, and the second electrode portion has a second width smaller than the first width.

Abstract: Embodiments of a plug for use in an electrostatic chuck are provided herein. In some embodiments, a plug for use in an electrostatic chuck includes a polymer sleeve having a central opening; and a core disposed in the central opening of the polymer sleeve, the core having a central protrusion and a peripheral ledge, wherein an outer surface of the core includes a helical channel extending from a lower surface of the core towards the peripheral ledge to at least partially define a gas flow path through the plug, and wherein the peripheral ledge is disposed between an upper surface of the polymer sleeve and the lower surface of the core.

Abstract: A method of transferring a micro device and an array of micro devices are disclosed. A carrier substrate carrying a micro device connected to a bonding layer is heated to a temperature below a liquidus temperature of the bonding layer, and a transfer head is heated to a temperature above the liquidus temperature of the bonding layer. Upon contacting the micro device with the transfer head, the heat from the transfer head transfers into the bonding layer to at least partially melt the bonding layer. A voltage applied to the transfer head creates a grip force which picks up the micro device from the carrier substrate.

Abstract: An apparatus for a plasma processing includes an annular member, a support unit, a chamber and a pressure control unit. The annular member has a groove or a protrusion circumferentially formed on a bottom surface thereof, the groove or the protrusion having a first thread circumferentially formed on a side surface. The support unit has a protrusion or a groove circumferentially formed on a placing surface on which the annular member is placed such that the groove or the protrusion of the annular member is fitted with the protrusion or the groove of the support unit, the protrusion or the groove of the support unit having a second thread circumferentially formed on a side surface thereof. The chamber has therein the support unit. Further, the pressure control unit controls a pressure in the chamber such that a driving force for circumferentially rotating the annular member is obtained.

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: 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: A substrate processing apparatus includes a rotary table configured to hold and rotate a substrate; an electronic component provided at the rotary table and configured to be rotated along with the rotary table; a first electrode unit provided at the rotary table and configured to be rotated along with the rotary table, the first electrode unit comprising multiple first electrodes electrically connected to the electronic component via multiple first conductive lines; an electric device configured to perform a power supply to the electronic component and a transmission/reception of signals; a second electrode unit comprising multiple second electrodes electrically connected to the electric device via multiple second conductive lines and arranged at positions respectively corresponding to the multiple first electrodes to be brought into contact with the multiple first electrodes; and an electrode moving device configured to connect/disconnect the first electrode unit to/from the second electrode unit.

Abstract: A substrate processing method performed in a chamber of a substrate processing apparatus is provided. The chamber includes a substrate support, an upper electrode, and a gas supply port. The substrate processing method includes (a) providing the substrate on the substrate support; (b) supplying a first processing gas into the chamber; (c) continuously supplying an RF signal into the chamber while continuously supplying a negative DC voltage to the upper electrode, to generate plasma from the first processing gas in the chamber; and (d) supplying a pulsed RF signal while continuously supplying the negative DC voltage to the upper electrode, to generate plasma from the first processing gas in the chamber. The process further includes repeating alternately repeating the steps (c) and (d), and a time for performing the step (c) once is 30 second or shorter.

Abstract: The present invention provides a method for plasma dicing a substrate. The method comprising providing a process chamber having a wall; providing a plasma source adjacent to the wall of the process chamber; providing a work piece support within the process chamber; placing the substrate onto a support film on a frame to form a work piece work piece; loading the work piece onto the work piece support; providing a clamping electrode for electrostatically clamping the work piece to the work piece support; providing a mechanical partition between the plasma source and the work piece; generating a plasma through the plasma source; and etching the work piece through the generated plasma.

Abstract: Methods and apparatus for preventing or reducing arcing of an electrostatic chuck in a process chamber. In some embodiments, a method of preventing or reducing arcing of an electrostatic chuck includes forming a first recess in at least a portion of a sidewall of the electrostatic chuck and filling the first recess with a conformable dielectric material that remains conformable (elastic) over a temperature range of at least approximately zero degrees Celsius to approximately 80 degrees Celsius. In some embodiments, the first recess is filled with the conformable dielectric material such that the conformable dielectric material does not bond to at least one surface of the first recess. The conformable dielectric material may also be used to fill a second recess in a dielectric sleeve adjacent to the electrostatic chuck.

Abstract: A substrate fixing apparatus includes: a base plate; an electrostatic adsorption member that adsorbs and retains a substrate; a support member that is disposed on the base plate to support the electrostatic adsorption member; and an adhesive layer that adhesively bonds the electrostatic adsorption member to the base plate. The support member directly contacts the base plate and the electrostatic adsorption member. An elastic modulus of the support member is higher than an elastic modulus of the adhesive layer.

Abstract: A system designed to couple a patterning device to a support structure having a plurality of burls includes a camera module, an actuator, and a controller. The camera module is designed to capture image data of a backside of the patterning device. The actuator is coupled to at least one burl of the plurality of burls and is designed to move the at least one burl. The controller is designed to receive the image data captured from the camera module and determine one or more locations of contamination on the backside of the patterning device from the image data. The controller is also designed to control the actuator to move the at least one burl of the plurality of burls away from the one or more locations of contamination on the backside of the patterning device, based on the determined locations of contamination.

Abstract: A plasma processing apparatus includes a sample stage on which a sample is placed an inside of the processing chamber; a dielectric membrane forming an upper surface portion of the sample stage; a plurality of film-shaped electrodes which is disposed in the dielectric membrane, to which a DC power from a DC power supply is supplied and in which an electrostatic force for attracting the sample is formed; and a bias electrode (ESC base metal) disposed below the dielectric membrane and supplied with radio frequency power for forming a radio frequency bias potential from a radio frequency power supply during the processing of the sample.

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: Embodiments of the present disclosure relate to a rotatable electrostatic chuck. In some embodiments, a rotatable electrostatic chuck includes a dielectric disk having at least one chucking electrode and a plurality of coolant channels; a cryogenic manifold coupled to the dielectric disk and having a coolant inlet and a coolant outlet both of which are fluidly coupled to the plurality of coolant channels; a shaft assembly coupled to the cryogenic manifold; a cryogenic supply chamber coupled to the shaft assembly; a supply tube coupled to the cryogenic supply chamber and to the coolant inlet to supply the cryogenic medium to the plurality of coolant channels, wherein the supply tube extends through the central opening of the shaft assembly; and a return tube coupled to the coolant outlet and to the cryogenic supply chamber, wherein the supply tube is disposed within the return tube.

Abstract: An assembly for clamping semiconductor wafers includes a plate and an electrostatic chuck mounted on the plate. A plurality of slots extends between respective portions of the electrostatic chuck to receive arms of an end-effector of a wafer-handler. The arms of the end-effector support semiconductor wafers being placed onto and removed from the electrostatic chuck.

Abstract: A ceramic layer is attached to a top surface of a base plate using a bond layer. The ceramic layer has a top surface configured to support a substrate. At least one clamp electrode is positioned within an upper region of the ceramic layer. A primary radiofrequency (RF) power delivery electrode is positioned within the ceramic layer at a location vertically below the at least one clamp electrode such that a region of the ceramic layer between the primary RF power delivery electrode and the at least one clamp electrode is substantially free of other electrically conductive material. A plurality of RF power delivery connection modules is distributed in a substantially uniform manner about a perimeter of the ceramic layer. Each of the RF power delivery connection modules is configured to form an electrical connection from the base plate to the primary RF power delivery electrode at its respective location.

Abstract: An electrostatic chuck includes a platform, a power feed pin, a tubular insulator, an adhesive layer, and a first primer. The platform includes an electrode. The power feed pin contacts the electrode. The tubular insulator is provided around the power feed pin. The adhesive layer bonds the platform and the tubular insulator together. The first primer is provided on a surface of the tubular insulator facing toward the adhesive layer.

Abstract: A susceptor including a generally circular body having a face with a radially inward section and a radially outward section proximate a circumference of the body, the radially outward section having at least one ring extending upward for contacting a bottom surface of a substrate, and wherein the radially inward section lacks a ring extending upward from the face.

Abstract: Exemplary support assemblies may include a top puck defining a substrate support surface, where the top puck is also characterized by a height. The assemblies may include a stem coupled with the top puck on a second surface of the top puck opposite the substrate support surface. The assemblies may include an RF electrode embedded within the top puck proximate the substrate support surface. The assemblies may include a heater embedded within the top puck. The assemblies may also include a ground shield embedded within the top puck. The ground shield may be characterized by an inner region extending radially through the top puck. The ground shield may further be characterized by an outer region extending perpendicular to the inner region.

Abstract: A ceramic heater includes an RF plate having a placement surface on which a wafer is to be placed, and made of a ceramic sintered body in which an RF electrode is embedded; and a heater plate made of a ceramic sintered body in which a heater is embedded, the RF plate and the heater plate being joined with a space interposed therebetween on a side opposite to the placement surface. The relationship among a minimum height H (mm) of the space in a direction perpendicular to the placement surface, a proportion A of a total area of portions where the RF plate and the heater plate are joined, with respect to an area of a plane along the placement surface that is defined by an outer edge of the placement surface, and a distance D (mm) between the RF electrode and the heater, satisfies H/A?1000 and H/A+(D?H)/(1?A)?14.

Abstract: Embodiments of an electrostatic chuck are provided herein. In some embodiments an electrostatic chuck includes an electrode, a dielectric body having a disk shape and covering the electrode, the dielectric body including a central region and a peripheral region, and the dielectric body including a lower surface having a central opening and an upper surface having a first opening in the central region and a plurality of second openings in the peripheral region, wherein the upper surface includes a plurality of protrusions and a diameter of each of the plurality of second openings is greater than 25.0 mils, and gas distribution channels that extend from the lower surface to the upper surface to define a plenum within the dielectric body.

Abstract: Embodiments described herein include a susceptor for semiconductor processing including an oriented graphite plate that may have a thickness of at least 1 mm. The susceptor may have a support member, and the oriented graphite plate may be disposed on the support member. The support member may have a center thermal conduit and an edge thermal conduit, and may be substantially solid between the center thermal conduit and the edge thermal conduit.

Abstract: A sintered body includes a ceramic substrate including sintered oxide particles, a through-hole formed in the ceramic substrate such that the side surfaces of the oxide particles exposed from an inner wall of the through-hole form a flat surface, and a porous body disposed in the through-hole, the porous body including spherical oxide ceramic particles and a mixed oxide configured to bind the spherical oxide ceramic particles.

Abstract: A first flash heating is performed in which a flash lamp emits a first flashing light to a semiconductor wafer having been heated to a first preheating temperature equal to or lower than 650 degrees C. by a light emission from a halogen lamp so that the temperature of a surface of the semiconductor wafer reaches 1000 degrees C. or higher. Then, a second flash heating is performed in which a second flashing light is emitted to the semiconductor wafer having been further heated by a light emission of the halogen lamp. Performing the first flash heating can suppress diffusion of impurity in the subsequent second flash heating. In the second flash heating, the impurity is activated and introduced crystal defects are recovered.

Abstract: An electrostatic chuck device includes: in order, an electrostatic chuck part having one principal surface serving as a placing surface on which a plate-shaped sample is placed, and having a built-in internal electrode for electrostatic attraction; a heating member bonded to a surface on the side opposite to the placing surface of the electrostatic chuck part in a pattern having gaps; a sheet material; and a base part having a function of cooling the electrostatic chuck part, in which a silicone resin sheet having a layer thickness of 10 ?m or more and less than 200 ?m and a Shore hardness (A) in a range of 10 to 70 is provided between the electrostatic chuck part and the heating member.

Abstract: A substrate processing apparatus includes a heat storage part on which a substrate is mounted, a tray including the heat storage part, a substrate transfer part including a rotary shaft and a rotating plate supported by the rotary shaft and being configured such that the tray can be mounted on the rotating plate, a plurality of bases arranged circumferentially around the rotary shaft; and a heater provided for each of the bases.

Abstract: According to the embodiment, an electrostatic chuck includes a ceramic dielectric substrate having a first major surface placing a suction object, a second major surface on an opposite side to the first major surface, a base plate supporting the ceramic dielectric substrate and including a gas introduction path, and a first porous part provided at a position between the base plate and the first major surface of the ceramic dielectric substrate and being opposite to the gas introduction path. The first porous part includes a first region positioned on the ceramic dielectric substrate side. The ceramic dielectric substrate includes a first substrate region positioned on the first region side. The first region and the first substrate region are provided in contact with each other, and an average particle diameter in the first region is different from an average particle diameter in the first substrate region.

Abstract: An insulator-type substrate is positioned on a support surface of a substrate support structure in exposure to a plasma. An initial clamping voltage is applied to an electrode within the substrate support structure to rapidly accumulate electrical charge on the support surface to hold the substrate. A backside cooling gas is flowed to a region between the substrate and the support surface, and a leak rate of the backside cooling gas is monitored. A steady clamping voltage is applied to the electrode, and the steady clamping voltage is adjusted in a step-wise manner to maintain the monitored leak rate of the backside cooling gas at just less than a maximum allowable leak rate. Or, a pulsed clamping voltage is applied to the electrode, and the pulsed clamping voltage is adjusted to maintain the monitored leak rate of the backside cooling gas at just less than the maximum allowable leak rate.

Abstract: An object is to provide an electrostatic chuck device having high heat resistance, which can be used even under high-temperature environment. An electrostatic chuck device includes: an electrostatic chuck section having a placing surface for placing a plate-shaped sample on one main surface thereof and an electrode for electrostatic adsorption; a temperature-controlling base section which is provided on the other side of the electrostatic chuck section in relation to the placing surface to cool the electrostatic chuck section; a heater element which is provided in a form of a layer between the electrostatic chuck section and the temperature-controlling base section; and a first adhesive layer which is provided between the heater element and the electrostatic chuck section to adhere the heater element and the electrostatic chuck section to each other, in which the first adhesive layer is made of inorganic glass or an inorganic material having a partially crystallized glass structure.

Abstract: Grinding, lapping and polishing basically work by making scratches in the body being ground, lapped or polished. The scratches typically are linear. The scratches gives rise to a directionality component of friction: the friction coefficient is less in the direction along the scratch than in a direction orthogonal, or across, the scratch. In a wafer handling/chucking situation, one wants the wafer to settle on the chuck, which involves the outer regions of the wafer moving radially with respect to the chuck. One can reduce friction in the radial direction by giving the lapping scratches a preferred orientation, namely, radial. This can be achieved by making the final passes of the lapping tool move predominantly in radial directions.

Abstract: An apparatus and method are provided for controlling the intensity and distribution of a plasma discharge in a plasma chamber. In one embodiment, a shaped electrode is embedded in a substrate support to provide an electric field with radial and axial components inside the chamber. In another embodiment, the face plate electrode of the showerhead assembly is divided into zones by isolators, enabling different voltages to be applied to the different zones. Additionally, one or more electrodes may be embedded in the chamber side walls.

Abstract: An electrostatic chuck is described to carry a workpiece for processing such as high power plasma processing. In embodiments, the chuck includes a top plate to carry the workpiece, the top plate having an electrode to grip the workpiece, a cooling plate under the top plate to cool the top plate, a gas hole through the cooling plate and the top plate to feed a gas to the workpiece through the top plate, and an aperture-reducing plug in the cooling plate gas hole to conduct gas flow through the hole.