Physical vapor deposition chamber particle reduction apparatus and methods

Physical vapor deposition processing chambers and methods of processing a substrate such as an EUV mask blank in a physical vapor deposition chamber are disclosed. An electric field and a magnetic field are utilized to deflect particles from a substrate being processed in the chamber.

TECHNICAL FIELD

The present disclosure relates generally to substrate processing systems, and more specifically, to physical vapor deposition (PVD) processing systems.

BACKGROUND

Sputtering, alternatively called physical vapor deposition (PVD), has long been used in depositing metals and related materials in the fabrication of semiconductor integrated circuits. Use of sputtering has been extended to depositing metal layers onto the sidewalls of high aspect-ratio holes such as vias or other vertical interconnect structures, as well as in the manufacture of extreme ultraviolet (EUV) mask blanks. In the manufacture of EUV mask blanks minimization of particle generation is desired, because particles negatively impact the properties of the final product.

Plasma sputtering may be accomplished using either DC sputtering or RF sputtering. Plasma sputtering typically includes a magnetron positioned at the back of the sputtering target to project a magnetic field into the processing space to increase the density of the plasma and enhance the sputtering rate. Magnets used in the magnetron are typically closed loop for DC sputtering and open loop for RF sputtering.

In plasma enhanced substrate processing systems, such as physical vapor deposition (PVD) chambers, high power density PVD sputtering with high magnetic fields and high DC Power can produce high energy at a sputtering target, and cause a large rise in surface temperature of the sputtering target. The sputtering target is cooled by contacting a target backing plate with cooling fluid. However, it has been determined that such cooling may not be sufficient to capture and remove heat from the target. Remaining heat in the target can result in significant mechanical bowing due to thermal gradient in the sputter material and across backing plate. The mechanical bowing increases as larger size wafers are being processed. This additional size aggravates the tendency of the target to bow/deform under thermal, pressure and gravitational loads. The impacts of bowing may include mechanical stress induced in the target material that can lead to fracture, damage to the target, and changes in distance from a magnet assembly to the face of the target material that can cause changes in the plasma properties (e.g., moving the processing regime out of an optimal or desired processing condition which affects the ability to maintain plasma, sputter/deposition rate, and erosion of the target).

In addition, higher target temperature results in re-sputtering of target material, which causes particle generation and defects on other parts of the PVD chamber and the wafer being processed in the chamber. Furthermore, the deposition on shields starts to crack of flake due to film stress, thermal stress and cohesion issues after certain thickness which causes another source of particle generation. There is need to provide apparatus and methods to efficiently reduce and/or prevent particles from being deposited on the substrate.

SUMMARY

One or more embodiments of the disclosure are directed to a physical vapor deposition chamber. The chamber comprises a chamber wall defining an inner volume within the physical vapor deposition chamber, a backing plate configured to support a sputtering target, the backing plate disposed in an upper section of the inner volume, a substrate support having a support surface to support a substrate below the backing plate, a central region between the backing plate and the substrate support, a process kit including a shield surrounding the central region, the shield comprising a cylindrical body having an inner surface, an upper portion and a lower portion, a first electrode assembly positioned on an inner surface of the shield, and a magnet positioned on the inner surface of the shield. The first electrode assembly is positioned and configured to create an electromagnetic field that laterally displaces particles generated during a physical vapor deposition process and the first electrode assembly and the magnet cooperate to prevent the particles from contacting a substrate on the substrate support during the physical vapor deposition process.

Other embodiments of the disclosure pertain to methods of processing a substrate in a physical vapor deposition chamber. The methods comprise placing a substrate on a substrate support within an inner volume of the physical vapor deposition chamber defined by a chamber wall. The inner volume includes an upper section and a lower section. The substrate support is in the lower section. Material is sputtered from a target of source material located above the substrate support in an upper section. There is a central region between the target of source material and the substrate support and process kit including a shield surrounding the central region. The shield comprises a cylindrical body having an inner surface, an upper portion and a lower portion. A magnet is positioned on an inner surface of the lower portion of the shield. A voltage is applied to a first electrode assembly positioned on an inner surface of the upper portion of the shield to laterally displace particles generated during a physical vapor deposition process and prevent the particles from contacting a substrate on the substrate support during the physical vapor deposition process.

Further embodiments of the disclosure are directed to methods of manufacturing an EUV mask blank in a physical vapor deposition chamber. The method comprises depositing alternating layers of a multilayer reflector material by sputtering material from a target on a substrate in a multi-cathode physical vapor deposition chamber. The substrate is placed within an inner volume of the physical vapor deposition chamber defined by a chamber wall. The inner volume includes an upper section, a lower section and a central region. The substrate is surrounded by a shield surrounding the central region. The shield has an inner surface, an upper portion and a lower portion. Particles are generated during the sputtering and laterally deflected with an electric field generated at the upper portion of the shield to prevent particles from being deposited on the substrate. A magnetic field is generated at a lower portion of the shield to prevent particles from being deposited on the substrate.

DETAILED DESCRIPTION

The term “on” indicates that there is direct contact between elements. The term “directly on” indicates that there is direct contact between elements with no intervening elements.

Those skilled in the art will understand that the use of ordinals such as “first” and “second” to describe process regions do not imply a specific location within the processing chamber, or order of exposure within the processing chamber.

FIG. 1depicts a simplified, cross-sectional view of a physical vapor deposition (PVD) processing system100in accordance with some embodiments of the present disclosure. Examples of other PVD chambers suitable for modification in accordance with the teachings provided herein include the ALPS® Plus and SIP ENCORE® PVD processing chambers, both commercially available from Applied Materials, Inc., of Santa Clara, Calif. Other processing chambers from Applied Materials, Inc. or other manufactures, including those configured for other types of processing besides PVD, may also benefit from modifications in accordance with the teachings disclosed herein.

In some embodiments of the present disclosure, the PVD processing system100includes a chamber body101removably disposed atop a PVD process chamber104. The chamber body101may include a target assembly114and a grounding assembly103. The process chamber104contains a substrate support106for receiving a substrate108thereon. The substrate support106may be located within a lower grounded enclosure wall110, which may be a chamber wall of the process chamber104. The lower grounded enclosure wall110may be electrically coupled to the grounding assembly103of the chamber body101such that an RF return path is provided to an RF or DC power source182disposed above the chamber body101. The RF or DC power source182may provide RF or DC power to the target assembly114as discussed below.

The substrate support106has a material-receiving surface facing a principal surface of a target assembly114and supports the substrate108to be sputter coated in planar position opposite to the principal surface of the target assembly114. The substrate support106may support the substrate108in a central region120of the process chamber104. The central region120is defined as the region above the substrate support106during processing (for example, between the target assembly114and the substrate support106when in a processing position).

In some embodiments, the substrate support106may be vertically movable to allow the substrate108to be transferred onto the substrate support106through a load lock valve (not shown) in the lower portion of the process chamber104and thereafter raised to a deposition, or processing position. A bellows122connected to a bottom chamber wall124may be provided to maintain a separation of the inner volume of the process chamber104from the atmosphere outside of the process chamber104while facilitating vertical movement of the substrate support106. One or more gases may be supplied from a gas source126through a mass flow controller128into the lower part of the process chamber104. An exhaust port130may be provided and coupled to a pump (not shown) via a valve132for exhausting the interior of the process chamber104and to facilitate maintaining a desired pressure inside the process chamber104.

An RF bias power source134may be coupled to the substrate support106in order to induce a negative DC bias on the substrate108. In addition, in some embodiments, a negative DC self-bias may form on the substrate108during processing. For example, RF energy supplied by the RF bias power source134may range in frequency from about 2 MHz to about 60 MHz, for example, non-limiting frequencies such as 2 MHz, 13.56 MHz, or 60 MHz can be used. In other applications, the substrate support106may be grounded or left electrically floating. Alternatively or in combination, a capacitance tuner136may be coupled to the substrate support106for adjusting voltage on the substrate108for applications where RF bias power may not be desired.

The process chamber104further includes a process kit shield, or shield138to surround the processing volume, or central region120of the process chamber104and to protect other chamber components from damage and/or contamination from processing. In some embodiments, the shield138may be connected to a ledge140of an upper grounded enclosure wall116of the process chamber104. As illustrated inFIG. 1, the chamber body101may rest on the ledge140of the upper grounded enclosure wall116. Similar to the lower grounded enclosure wall110, the upper grounded enclosure wall116may provide a portion of the RF return path between the lower grounded enclosure wall116and the grounding assembly103of the chamber body101. However, other RF return paths are possible, such as via the grounded shield138.

The shield138extends downwardly and may include a generally tubular portion having a generally constant diameter that generally surrounds the central region120. The shield138extends along the walls of the upper grounded enclosure wall116and the lower grounded enclosure wall110downwardly to below a top surface of the substrate support106and returns upwardly until reaching a top surface of the substrate support106(e.g., forming a u-shaped portion at the bottom of the shield138). A cover ring148rests on the top of an upwardly extending inner portion of the shield138when the substrate support106is in its lower, loading position but rests on the outer periphery of the substrate support106when it is in its upper, deposition position to protect the substrate support106from sputter deposition. An additional deposition ring (not shown) may be used to protect the edges of the substrate support106from deposition around the edge of the substrate108.

In some embodiments, a magnet152may be disposed about the process chamber104to selectively provide a magnetic field between the substrate support106and the target assembly114. For example, as shown inFIG. 1, the magnet152may be disposed about the outside of the enclosure wall110in a region just above the substrate support106when in processing position. In some embodiments, the magnet152may be disposed additionally or alternatively in other locations, such as adjacent the upper grounded enclosure wall116. The magnet152may be an electromagnet and may be coupled to a power source (not shown) for controlling the magnitude of the magnetic field generated by the electromagnet.

The chamber body101generally includes the grounding assembly103disposed about the target assembly114. The grounding assembly103may include a grounding plate156having a first surface157that may be generally parallel to and opposite a backside of the target assembly114. A grounding shield112may extend from the first surface157of the grounding plate156and surround the target assembly114. The grounding assembly103may include a support member175to support the target assembly114within the grounding assembly103.

In some embodiments, the support member175may be coupled to a lower end of the grounding shield112proximate an outer peripheral edge of the support member175and extends radially inward to support a seal ring181, the target assembly114and optionally, a dark space shield179. The seal ring181may be a ring or other annular shape having a desired cross-section. The seal ring181may include two opposing planar and generally parallel surfaces to facilitate interfacing with the target assembly114, such as the backing plate assembly160, on a first side of the seal ring181and with the support member175on a second side of the seal ring181. The seal ring181may be made of a dielectric material, such as ceramic. The seal ring181may insulate the target assembly114from the ground assembly103.

The dark space shield179is generally disposed about an outer edge of the target assembly114, such about an outer edge of a source material113of the target assembly114. In some embodiments, the seal ring181is disposed adjacent to an outer edge of the dark space shield179(i.e., radially outward of the dark space shield179). In some embodiments, the dark space shield179is made of a dielectric material, such as ceramic. By providing a dark space shield179, arcing between the dark space shield and adjacent components that are RF hot may be avoided or minimized. Alternatively, in some embodiments, the dark space shield179is made of a conductive material, such as stainless steel, aluminum, or the like. By providing a conductive dark space shield179a more uniform electric field may be maintained within the PVD processing system100, thereby promoting more uniform processing of substrates therein. In some embodiments, a lower portion of the dark space shield179may be made of a conductive material and an upper portion of the dark space shield179may be made of a dielectric material.

The support member175may be a generally planar member having a central opening to accommodate the dark space shield179and the target assembly114. In some embodiments, the support member175may be circular, or disc-like in shape, although the shape may vary depending upon the corresponding shape of the chamber lid and/or the shape of the substrate to be processed in the PVD processing system100. In use, when the chamber body101is opened or closed, the support member175maintains the dark space shield179in proper alignment with respect to the target assembly114, thereby minimizing the risk of misalignment due to chamber assembly or opening and closing the chamber body101.

The PVD processing system100may include a source distribution plate158opposing a backside of the target assembly114and electrically coupled to the target assembly114along a peripheral edge of the target assembly114. The target assembly114may comprise a source material113to be deposited on a substrate, such as the substrate108during sputtering, such as a metal, metal oxide, metal alloy, or the like. In one or more embodiments, the target assembly114includes a backing plate assembly160to support the source material113. The source material113may be disposed on a substrate support facing side of the backing plate assembly160as illustrated inFIG. 1. The backing plate assembly160may comprise a conductive material, such as copper-zinc, copper-chrome, or the same material as the target, such that RF and DC power can be coupled to the source material113via the backing plate assembly160. Alternatively, the backing plate assembly160may be non-conductive and may include conductive elements (not shown) such as electrical feedthroughs or the like.

In one or more embodiments, the backing plate assembly160includes a backing plate161and a cover plate162. The backing plate161and the cover plate162may be disc shaped, rectangular, square, or any other shape that may be accommodated by the PVD processing system100. A front side of the backing plate is configured to support the source material113such that a front surface of the source material opposes the substrate108when present. The source material113may be coupled to the backing plate161in any suitable manner. For example, in some embodiments, the source material113may be diffusion bonded to the backing plate161.

A plurality of channels169may be disposed between the backing plate161and the cover plate162. In one or more embodiments, the backing plate161may have the plurality of channels169formed in a backside of the backing plate161with the cover plate162providing a cap/cover over each of the channels. In other embodiments, the plurality of channels169may be formed partially in the backing plate161and partially in the cover plate162. Still, in other embodiments, the plurality of channels169may be formed entirely in the cover plate162, while the backing plate caps/covers each of the plurality of channels169. The backing plate161and the cover plate162may be coupled together.

In some embodiments, the cover plate162is eliminated, and the backing plate161is a monolithic material. Such a backing plate161of monolithic material can be formed by 3D printing, and the plurality of channels169are formed during the 3D printing process. In some embodiments, the plurality of channels169are configured to flow cooling fluid, and the backing plate161and the cover plate162are coupled together to form a substantially water tight seal (e.g., a fluid seal between the backing plate161and the cover plates162) to prevent leakage of coolant provided to the plurality of channels169. That is, the cooling fluid is in direct contact with the channels169. For example, in some embodiments, the backing plate161and the cover plate162are brazed together to form a substantially water tight seal or they may be coupled by diffusion bonding, brazing, gluing, pinning, riveting, or any other fastening means to provide a liquid seal, and the channels169formed between the backing plate161and the cover plate162directly contact cooling fluid. However, in other embodiments, the backing plate161has the plurality of channels169machined therein. The cover plate162is then optionally machined (or not machined). Brazing paste is placed between the backing plate161and the cover plate162. Electron beam (E-beam) welding is then utilized to fasten the backing plate161and the cover plate162together. Thereafter, the fastened components can be heated to complete the fastening process, and then the fastened components may be machined to the final tolerance and specifications. Then the source material in the form of a target can be bonded to the backing plate161or cover plate162with indium solder. As will be described further below, according to some embodiments of the instant disclosure, a fluid tight seal between the backing plate161and the cover plate162is not necessary because the cooling fluid is contained within tubing which is disposed within the channels169.

The backing plate161and the cover plate162may comprise an electrically conductive material, such as an electrically conductive metal or metal alloy including brass, aluminum, copper, aluminum alloys, copper alloys, or the like. In some embodiments, the backing plate161may be a machinable metal or metal alloy (e.g., C18200 chromium copper alloy) such that the channels may be machined or otherwise created on a surface of the backing plate161. In some embodiments, the cover plate162may be a machinable metal or metal alloy, (e.g., C18200 chromium copper alloy) having a stiffness/elastic modulus greater than the metal or metal alloy of the backing plate to provide improved stiffness and lower deformation of backing plate assembly160. The materials and sizes of the backing plate161and the cover plate162should be such that the stiffness of the entire backing plate assembly160will withstand the vacuum, gravitational, thermal, and other forces exerted on the target assembly114during deposition process, without (or with very little) deformation or bowing of the target assembly114including the source material113(i.e., such that the front surface of source material113remains substantially parallel to the top surface of a substrate108).

In some embodiments, the overall thickness of the target assembly114may be between about 20 mm to about 100 mm. For example, the source material113may be about 10 to about 15 mm thick and the backing plate assembly may be about 10 to about 30 mm thick. Other thicknesses may also be used.

In some embodiments, the target assembly includes one or more inlets (not shown inFIG. 1) fluidly coupled with the channels169or with tubing. The one or more inlets are configured to receive a heat exchange fluid and to provide the heat exchange fluid to the plurality of channels169or to the tubing. For example, at least one of the one or more inlets may be a plenum to distribute the heat exchange fluid to the plurality of channels169or to tubing. The assembly further includes one or more outlets (not shown inFIG. 1and discussed in detail below) disposed through the cover plate162and fluidly coupled to a corresponding inlet by the plurality of channels169or tubing. For example, at least one of the one or more outlets may be a plenum to collect the heat exchange fluid from a plurality of the one or more channels or tubing. In some embodiments, one inlet and one outlet are provided and each set of channels in the plurality of set of channels169is fluidly coupled to the one inlet and the one outlet.

The inlets and outlets may be disposed on or near a peripheral edge of the cover plate162or backing plate161. In addition, the inlets and outlets may be disposed on the cover plate162such that supply conduits167coupled to the one or more inlets, and return conduits coupled to the one or more outlets, do not interfere with the rotation of a magnetron assembly196in cavity170. In other embodiments, the inlets and outlets may be disposed on the backing plate161such that supply conduits167coupled to the one or more inlets, and return conduits (not shown due to cross section) coupled to the one or more outlets, do not interfere with the rotation of a magnetron assembly196in cavity170. In still other embodiments, the inlets and outlets may be coupled to tubing such that supply conduits167coupled to the one or more inlets, and return conduits (not shown due to cross section), coupled to the one or more outlets, do not interfere with the rotation of a magnetron assembly196in cavity170.

In some embodiments, PVD processing system100may include one or more supply conduits167to supply heat exchange fluid to the backing plate assembly160. In some embodiments, each inlet may be coupled to a corresponding supply conduit167. Similarly, each outlet may be coupled to a corresponding return conduit. Supply conduits167and return conduits may be made of insulating materials. The fluid supply conduit167may include a seal ring (e.g., a compressible o-ring or similar gasket material) to prevent heat exchange fluid leakage between the fluid supply conduit167and an inlet. In some embodiments, a top end of supply conduits167may be coupled to a fluid distribution manifold163disposed on the top surface of the chamber body101. The fluid distribution manifold163may be fluidly coupled to the plurality of fluid supply conduits167to supply heat exchange fluid to each of the plurality of fluid supply conduits via supply lines165. Similarly, a top end of return conduits may be coupled to a return fluid manifold (not shown, but similar to163) disposed on the top surface of the chamber body101. The return fluid manifold may be fluidly coupled to the plurality of fluid return conduits to return heat exchange fluid from each of the plurality of fluid return conduits via return lines.

The fluid distribution manifold163may be coupled to a heat exchange fluid source (not shown) to provide a heat exchange fluid in the form of a liquid to the backing plate assembly160. The heat exchange fluid may be any process compatible liquid coolant, such as ethylene glycol, deionized water, a perfluorinated polyether (such as Galden®, available from Solvay S. A.), or the like, or solutions or combinations thereof. In some embodiments, the flow of coolant through the channels169or tubing may be about 8 to about 20 gallons per minute, in sum total, although the exact flows will depend upon the configuration of the coolant channels, available coolant pressure, or the like.

A conductive support ring164, having a central opening, is coupled to a backside of the cover plate162along a peripheral edge of the cover plate162. In some embodiments, in place of separate supply and return conduits, the conductive support ring164may include a ring inlet to receive heat exchange fluid from a fluid supply line (not shown). The conductive support ring164may include an inlet manifold, disposed within the body of the conductive support ring164, to distribute the heat exchange fluid to an inlet connected to tubing or the channels169. The conductive support ring164may include an outlet manifold, disposed within the body of the conductive support ring164, to receive the heat exchange fluid from one or more outlets, and a ring outlet to output the heat exchange fluid from the conductive support ring164. The conductive support ring164and the backing plate assembly160may be threaded together, pinned, bolted, or fastened in a process compatible manner to provide a liquid seal between the conductive support ring164and the cover plate162. O-rings or other suitable gasket materials may be provided to facilitate providing a seal between the conductive support ring164and the cover plate162.

In some embodiments, the target assembly114may further comprise a central support member192to support the target assembly114within the chamber body101. The central support member192may be coupled to a center portion of the backing plate161and the cover plate162and extend perpendicularly away from the backside of the cover plate162. In some embodiments, a bottom portion of the central support member192may be threaded into a central opening in the backing plate161and the cover plate162. In other embodiments, a bottom portion of the central support member192may be bolted or clamped to a central portion of the backing plate161and the cover plate162. A top portion of the central support member192may be disposed through the source distribution plate158and includes a feature which rests on a top surface of the source distribution plate158that supports the central support member192and target assembly114.

In some embodiments, the conductive support ring164may be disposed between the source distribution plate158and the backside of the target assembly114to propagate RF energy from the source distribution plate to the peripheral edge of the target assembly114. The conductive support ring164may be cylindrical, with a first end166coupled to a target-facing surface of the source distribution plate158proximate the peripheral edge of the source distribution plate158and a second end168coupled to a source distribution plate-facing surface of the target assembly114proximate the peripheral edge of the target assembly114. In some embodiments, the second end168is coupled to a source distribution plate facing surface of the backing plate assembly160proximate the peripheral edge of the backing plate assembly160.

The PVD processing system100may include a cavity170disposed between the backside of the target assembly114and the source distribution plate158. The cavity170may at least partially house the magnetron assembly196as discussed below. The cavity170is at least partially defined by the inner surface of the conductive support ring164, a target facing surface of the source distribution plate158, and a source distribution plate facing surface (e.g., backside) of the target assembly114(or backing plate assembly160).

An insulative gap180is provided between the grounding plate156and the outer surfaces of the source distribution plate158, the conductive support ring164, and the target assembly114(and/or backing plate assembly160). The insulative gap180may be filled with air or some other suitable dielectric material, such as a ceramic, a plastic, or the like. The distance between the grounding plate156and the source distribution plate158depends on the dielectric material between the grounding plate156and the source distribution plate158. Where the dielectric material is predominantly air, the distance between the grounding plate156and the source distribution plate158may be between about 15 mm and about 40 mm.

The grounding assembly103and the target assembly114may be electrically separated by the seal ring181and by one or more of insulators (not shown) disposed between the first surface157of the grounding plate156and the backside of the target assembly114, e.g., a non-target facing side of the source distribution plate158.

The PVD processing system100has an RF or DC power source182connected to an electrode154(e.g., a RF feed structure). The electrode154may pass through the grounding plate156and is coupled to the source distribution plate158. The RF or DC power source182may include an RF generator and a matching circuit, for example, to minimize reflected RF energy reflected back to the RF generator during operation. For example, RF energy supplied by the RF or DC power source182may range in frequency from about 13.56 MHz to about 162 MHz or above. For example, non-limiting frequencies such as 13.56 MHz, 27.12 MHz, 40.68 MHz, 60 MHz, or 162 MHz can be used.

In some embodiments, the PVD processing system100may include a second energy source183to provide additional energy to the target assembly114during processing. In some embodiments, the second energy source183may be a DC power source to provide DC energy, for example, to enhance a sputtering rate of the target material (and hence, a deposition rate on the substrate). In some embodiments, the second energy source183may be a second RF power source, similar to the RF or DC power source182, to provide RF energy, for example, at a second frequency different than a first frequency of RF energy provided by the RF or DC power source182. In embodiments where the second energy source183is a DC power source, the second energy source may be coupled to target assembly114in any location suitable to electrically couple the DC energy to the target assembly114, such as the electrode154or some other conductive member (such as the source distribution plate158, discussed below). In embodiments where the second energy source183is a second RF power source, the second energy source may be coupled to the target assembly114via the electrode154.

The electrode154may be cylindrical or otherwise rod-like and may be aligned with a central axis186of the PVD processing system100(e.g., the electrode154may be coupled to the target assembly at a point coincident with a central axis of the target, which is coincident with the central axis186). The electrode154, aligned with the central axis186of the PVD processing system100, facilitates applying RF energy from the RF or DC power source182to the target assembly114in an axisymmetrical manner (e.g., the electrode154may couple RF energy to the target at a single point aligned with the central axis of the PVD chamber). The central position of the electrode154helps to eliminate or reduce deposition asymmetry in substrate deposition processes. The electrode154may have any suitable diameter. For example, although other diameters may be used, in some embodiments, the diameter of the electrode154may be about 0.5 to about 2 inches. The electrode154may generally have any suitable length depending upon the configuration of the PVD chamber. In some embodiments, the electrode may have a length of between about 0.5 to about 12 inches. The electrode154may be fabricated from any suitable conductive material, such as aluminum, copper, silver, or the like. Alternatively, in some embodiments, the electrode154may be tubular. In some embodiments, the diameter of the tubular electrode154may be suitable, for example, to facilitate providing a central shaft for the magnetron.

The electrode154may pass through the ground plate156and is coupled to the source distribution plate158. The ground plate156may comprise any suitable conductive material, such as aluminum, copper, or the like. The open spaces between the one or more insulators (not shown) allow for RF wave propagation along the surface of the source distribution plate158. In some embodiments, the one or more insulators may be symmetrically positioned with respect to the central axis186of the PVD processing system. Such positioning may facilitate symmetric RF wave propagation along the surface of the source distribution plate158and, ultimately, to a target assembly114coupled to the source distribution plate158. The RF energy may be provided in a more symmetric and uniform manner as compared to conventional PVD chambers due, at least in part, to the central position of the electrode154.

One or more portions of a magnetron assembly196may be disposed at least partially within the cavity170. The magnetron assembly provides a rotating magnetic field proximate the target to assist in plasma processing within the chamber body101. In some embodiments, the magnetron assembly196may include a motor176, a motor shaft174, a gear box178, a gear box shaft assembly184, and a rotatable magnet (e.g., a plurality of magnets188coupled to a magnet support member172), and divider194. In some embodiments, the magnetron assembly196remains stationary.

In some embodiments, the magnetron assembly196is rotated within the cavity170. For example, in some embodiments, the motor176, motor shaft174, gear box178, and gear box shaft assembly184may be provided to rotate the magnet support member172. In conventional PVD chambers having magnetrons, the magnetron drive shaft is typically disposed along the central axis of the chamber, preventing the coupling of RF energy in a position aligned with the central axis of the chamber. In one or more embodiments, the electrode154is aligned with the central axis186of the PVD chamber. As such, in some embodiments, the motor shaft174of the magnetron may be disposed through an off-center opening in the ground plate156. The end of the motor shaft174protruding from the ground plate156is coupled to a motor176. The motor shaft174is further disposed through a corresponding off-center opening through the source distribution plate158(e.g., a first opening146) and coupled to a gear box178. In some embodiments, one or more second openings (not shown) may be disposed through the source distribution plate158in a symmetrical relationship to the first opening146to advantageously maintain axisymmetric RF distribution along the source distribution plate158. The one or more second openings may also be used to allow access to the cavity170for items such as optical sensors or the like. In one or more embodiments, the backing plate assemblies described herein are particularly useful in multi-cathode PVD systems with rotating magnets. Prior art designs with larger cooling cavities limited the ability to utilize rotating magnets

The gear box178may be supported by any suitable means, such as by being coupled to a bottom surface of the source distribution plate158. The gear box178may be insulated from the source distribution plate158by fabricating at least the upper surface of the gear box178from a dielectric material, or by interposing an insulator layer (not shown) between the gear box178and the source distribution plate158, or the like, or by constructing the motor shaft174out of a suitable dielectric material. The gear box178is further coupled to the magnet support member172via the gear box shaft assembly184to transfer the rotational motion provided by the motor176to the magnet support member172(and hence, the plurality of magnets188).

The magnet support member172may be constructed from any material suitable to provide adequate mechanical strength to rigidly support the plurality of magnets188. For example, in some embodiments, the magnet support member172may be constructed from a non-magnetic metal, such as non-magnetic stainless steel. The magnet support member172may have any shape suitable to allow the plurality of magnets188to be coupled thereto in a desired position. For example, in some embodiments, the magnet support member172may comprise a plate, a disk, a cross member, or the like. The plurality of magnets188may be configured in any manner to provide a magnetic field having a desired shape and strength.

Alternatively, the magnet support member172may be rotated by any other means with sufficient torque to overcome the drag caused on the magnet support member172and attached plurality of magnets188, when present, in the cavity170. For example, in some embodiments, (not shown), the magnetron assembly196may be rotated within the cavity170using a motor176and motor shaft174disposed within the cavity170and directly connected to the magnet support member172(for example, a pancake motor). The motor176must be sized sufficiently to fit within the cavity170, or within the upper portion of the cavity170when the divider194is present. The motor176may be an electric motor, a pneumatic or hydraulic drive, or any other process-compatible mechanism that can provide the required torque.

Still referring toFIG. 1and also referring toFIGS. 2-8, the physical vapor deposition (PVD) chamber104comprises the chamber wall defining an inner volume within the physical vapor deposition chamber104, the backing plate161configured to support a sputtering target114, the backing plate161disposed in an upper section120aof the inner volume closer to the target114. The PVD chamber104further comprises a substrate support106in a lower section120bof the inner volume having a support surface107to support a substrate (not shown) below the backing plate161. There is a central region120between the backing plate161and the substrate support106. The PVD chamber further comprises process kit including the shield138surrounding the central region120, the shield comprising a cylindrical body having an inner surface, an upper portion closer to the backing plate161and a lower portion closer to the substrate support106. The PVD chamber104further comprises a first electrode assembly200positioned on an inner surface138aof the shield138and a magnet204positioned on the inner surface138aof the shield138, the first electrode assembly200positioned and configured to laterally displace particles generated during a physical vapor deposition process and the first electrode assembly200and the magnet204cooperate to prevent the particles from contacting a substrate on the substrate support106during the physical vapor deposition process.

In some embodiments, the magnet204is positioned at the lower portion of the shield138and the first electrode assembly200is positioned at the upper portion of the shield138, as shown inFIG. 1andFIG. 8. The PVD chamber may further comprising a second electrode assembly202positioned on an inner surface and at the upper portion of the shield and a power supply240to supply a voltage to the first electrode assembly and the second electrode assembly. In some embodiments, the first electrode assembly200and the second electrode assembly202are arc-shaped, as shown inFIG. 2. However, the shape of the electrode of the electrode assembly can be other shapes such as the electrode assembly300shown inFIG. 4with a circular shape.

As shown inFIGS. 5A-5F, the electrode assembly200(and the electrode assembly202) may comprise an arc-shaped electrode210as shown inFIG. 5B, including mounting studs212. The electrode assembly200(and the electrode assembly202) can further comprise a main electrode body214including mounting holes216to permit mounting of the electrode210by mounting studs212. The electrode assembly200(and the electrode assembly202) can further comprise a terminal218that fits within the main electrode body214, and an insulator220that fits within the main electrode body214. The electrode assembly can be mounted in the shield218shown inFIG. 5E.

In one or more embodiments, the PVD chamber further comprises a controller250configured to selectively apply predetermined voltage differences between the first electrode assembly200and the second electrode assembly202that create the electric field that laterally displace particles generated during the physical vapor deposition process. In some embodiments the magnet204comprises a static magnet. In some embodiments, the magnet204comprises an electromagnet, and the physical vapor deposition chamber comprises a second power supply260and a second controller270that selectively applies current such that that the electromagnet creates a magnetic field that deflects particles generated during the physical vapor deposition process away from the substrate support. As best shown inFIGS. 6-8, the PVD chamber further comprises a magnet cover230which covers the magnet204, which may be an electromagnet. In one or more embodiments, the cover230is made from a non-magnetic material such as aluminum. According to one or more embodiments, the height of the first electrode200and the second electrode202can be increased to increase the intensity of electric field that increases towards the upper portion of the chamber. In some embodiments, when a particle enters between two electrodes (first electrode200, second electrode202), then gravity and electrostatic force created by the electric field act simultaneously until the particle passes through the gap between two electrodes. The gravity force causes vertical displacement of the particle while electrostatic force results lateral displacement. The electrostatic force required to laterally displace the particle can be determined empirically or by modeling, and the first controller250and/or second controller270can be used to provide the voltage required to the first and second electrodes and current to the magnet204.

Another aspect of the disclosure pertains to a method of processing a substrate in a physical vapor deposition chamber, the method comprising placing a substrate on a substrate support within an inner volume of the physical vapor deposition chamber defined by a chamber wall, the inner volume including an upper section and a lower section, the substrate support in the lower section. The method further comprises sputtering material from a target of source material located above the substrate support in an upper section, there being a central region between the target of source material and the substrate support and process kit including a shield surrounding the central region, the shield comprising a cylindrical body having an inner surface, an upper portion and a lower portion, and a magnet positioned on an inner surface of the lower portion of the shield. The method further comprises applying a voltage to a first electrode assembly positioned on an inner surface of the upper portion of the shield to laterally displace particles generated during a physical vapor deposition process and prevent the particles from contacting a substrate on the substrate support during the physical vapor deposition process.

In some embodiment of the method there is a second electrode assembly positioned on an inner surface and at the upper portion of the shield, the method further comprising applying a voltage to the first electrode assembly and the second electrode assembly. In some embodiments, the method further comprises selectively applying predetermined voltage differences between the first electrode assembly and the second electrode assembly to create an electric field that laterally displace particles generated during the physical vapor deposition process. In some embodiments of the method, the magnet comprises an electromagnet, and the method further comprises selectively applying current so the electromagnet so that that the electromagnet generates a magnetic field that deflects particles generated during the physical vapor deposition process away from the substrate support.

Some embodiments of the method further comprise creating a static electromagnetic field or creating a dynamic electromagnetic field. Some embodiments of the method comprise separately tuning the magnetic field and the electric field.

The PVD processing chambers and methods described herein may be particularly useful in the manufacture of extreme ultraviolet (EUV) mask blanks. An EUV mask blank is an optically flat structure used for forming a reflective mask having a mask pattern. In one or more embodiments, the reflective surface of the EUV mask blank forms a flat focal plane for reflecting the incident light, such as the extreme ultraviolet light. An EUV mask blank comprises a substrate providing structural support to an extreme ultraviolet reflective element such as an EUV reticle. In one or more embodiments, the substrate is made from a material having a low coefficient of thermal expansion (CTE) to provide stability during temperature changes. The substrate according to one or more embodiments is formed from a material such as silicon, glass, oxides, ceramics, glass ceramics, or a combination thereof.

An EUV mask blank includes a multilayer stack, which is a structure that is reflective to extreme ultraviolet light. The multilayer stack includes alternating reflective layers of a first reflective layer and a second reflective layer. The first reflective layer and the second reflective layer form a reflective pair. In a non-limiting embodiment, the multilayer stack includes a range of 20-60 of the reflective pairs for a total of up to 120 reflective layers.

The first reflective layer and the second reflective layer can be formed from a variety of materials. In an embodiment, the first reflective layer and the second reflective layer are formed from silicon and molybdenum, respectively. The multilayer stack forms a reflective structure by having alternating thin layers of materials with different optical properties to create a Bragg reflector or mirror. The alternating layer of, for example, molybdenum and silicon can be formed by physical vapor deposition, for example, in a multi-cathode source chamber. An absorbing layer made from a material that absorbs EUV radiation, such as a tantalum-containing material (e.g., TaN or TaON) can also be formed by physical vapor deposition utilizing the chambers and methods described herein.

In some embodiments, a method of manufacturing an EUV mask blank in a physical vapor deposition chamber is provided. The method comprises depositing alternating layers of a multilayer reflector material by sputtering material from a target on a substrate in a multi-cathode physical vapor deposition chamber, the substrate placed within an inner volume of the physical vapor deposition chamber defined by a chamber wall, the inner volume including an upper section, a lower section and a central region, and the substrate surrounded by a shield surrounding the central region, the shield having an inner surface, an upper portion and a lower portion. The method further comprises laterally deflecting particles generated during the sputtering with an electric field generated at the upper portion of the shield to prevent particles from being deposited in the substrate; and generating a magnetic field at a lower portion of the shield to prevent particles from being deposited on the substrate.

In some embodiments, the method further comprises further comprising selectively applying predetermined voltage differences between a first electrode assembly and a second electrode assembly located in the upper portion of the shield to create the electric field. The method may further comprise selectively applying current to an electromagnetic located in the lower portion of the shield to generate the magnetic field. The method may further comprise creating a static electromagnetic field or a dynamic electromagnetic field. The method may further comprise separately tuning the magnetic field and the electric field.

Referring now toFIG. 9, an upper portion of a multi-cathode source chamber500is shown in accordance with an embodiment. The multi-cathode chamber500includes a base structure501with a cylindrical body portion502capped by a top adapter504. The top adapter504has provisions for a number of cathode sources, such as cathode sources506,508,510,512, and514, positioned around the top adapter504. The PVD processing system100described with respect toFIG. 1can be utilized in the multi-cathode source chamber500to form the multilayer stack, as well as capping layers and absorber layers. For example, the physical vapor deposition systems can form layers of silicon, molybdenum, titanium oxide, titanium dioxide, ruthenium oxide, niobium oxide, ruthenium tungsten, ruthenium molybdenum, ruthenium niobium, chromium, tantalum, nitrides, compounds, or a combination thereof. Although some compounds are described as an oxide, it is understood that the compounds can include oxides, dioxides, atomic mixtures having oxygen atoms, or a combination thereof.

Thus, PVD chambers and methods are provided which can address particles that are generated from the target during interaction with the magnet and plasma. Such charged particles from the target during deposition process can reach the blank substrate and add defects, however, the methods and PVD chambers described herein prevent these charged particles from reaching a substrate during processing. The methods and apparatus can also prevent particles that accumulate on chamber walls or shield surfaces from reaching the substrate and prevent defects. The methods and apparatus can reduce defects during deposition of EUV mask blanks in PVD chambers of multi-cathode PVD systems.