Multicathode PVD system for high aspect ratio barrier seed deposition

Apparatus and methods for multi-cathode barrier seed deposition for high aspect ratio features in a physical vapor deposition (PVD) process are provided herein. In some embodiments, a PVD chamber includes a pedestal disposed within a processing region of the PVD chamber. The pedestal rotates with a workpiece on it. The PVD chamber includes a lid assembly includes a first target and a second target of a same target material, where a first surface of the first target defines a first zone of the processing region a first distance from the upper surface of the pedestal, and a second surface of the second target defines a second zone of the processing region a second distance from the plane of the upper surface of the pedestal. A system controller is configured to simultaneously control a first voltage bias for the first target and a second voltage bias for the second target.

BACKGROUND

Field

Embodiments of the present disclosure generally relate to physical vapor deposition (PVD) film formation on workpieces in an electronic device fabrication process, and more particularly, to apparatus and methods for improving film deposition uniformity for high aspect ratio PVD.

Description of the Related Art

Electronic device fabrication processes today often involve the use of a physical vapor deposition (PVD), or sputtering, process in a dedicated PVD chamber. The source of the sputtered material may include a planar or rotary sputtering target formed from pure metals, alloys, or ceramic materials. A magnet array, which is typically disposed within an assembly that is often referred to as a magnetron, is used to generate a magnetic field in the vicinity of the target. During processing, a high voltage is applied to the target to generate a plasma and enable the sputtering process. Because the voltage source provides a negative bias to a target, the target may also be referred to as the “cathode.” The high voltage generates an electric field inside the PVD chamber that is used to enable sputtering of the target material and generate and emit electrons from the target that are used to generate and sustain a plasma near the underside of the target. The magnet array forms a magnetic field that traps electrons and thus confines a significant portion of the plasma close to the target. The trapped electrons can then collide with and ionize the gas atoms disposed within the processing region of the PVD chamber. The collision between the trapped electron(s) and gas atoms will cause the gas atoms to emit electrons that are used to sustain and further increase the plasma density within the processing region of the PVD chamber. The plasma may include argon atoms, positively charged argon ions, free electrons, and ionized and neutral metal atoms sputtered from the target. The argon ions are accelerated towards the target due to the negative bias and collide with a surface of the target causing atoms of the target material to be ejected therefrom. The ejected atoms of target material then travel towards the workpiece and chamber shielding to incorporate into the growing thin film thereon.

PVD sputtering and control of film deposition uniformity are especially challenging when processing workpieces that have high aspect ratio features. For example, high aspect ratio vias may be formed on silicon or other semiconductor substrates, or silicon, glass, or organic interposers, such as those used for heterogeneous integration. High density vias in an interposer can enable vertical communication between chip-level interconnects and package-level interconnects. Vias are generally seeded with a layer of metal (e.g., copper) via PVD sputtering, then are electro-plated to fill the vias. In order to fill the high aspect ratio vias by electro-plating, the seed layers need to be uniformly deposited across the whole via to maintain the electrical path.

PVD sputtering can provide, relative to other deposition techniques, high step coverage, good uniformity over a large area, and high throughput. However, due to line-of-sight nature of PVD processes, a seed layer deposited within high aspect ratio vias may exhibit poor step-coverage and uniformity across a workpiece. In some cases, in order to have enough coverage of the sidewalls and bottom of the vias for successful electro-plating, PVD sputtering may need to be performed for a longer time. PVD sputtering from a single source (e.g., cathode), while sometimes cost effective from a hardware perspective, can only provide a single sputtering profile, a fixed throw distance, fixed deposition angle set by the orientation of the face of the target relative to the surface of the substrate, and a single ion energy distribution at any instant in time during processing.

Accordingly, there is a need in the art for apparatus and methods for improving film deposition uniformity and feature wall coverage for high aspect ratio features in PVS sputtering systems.

SUMMARY

Embodiments described herein generally relate to physical vapor deposition (PVD) film formation on workpieces in an electronic device fabrication process. More particularly, embodiments described herein provide apparatus and methods for improving film deposition uniformity and coverage for high aspect ratio features.

In one embodiment, a PVD chamber includes a pedestal disposed within a processing region of the PVD chamber. The pedestal has an upper surface that is configured to support a workpiece thereon. The PVD chamber includes a first motor is coupled to the pedestal, the first motor configured to rotate the pedestal about a first axis that is perpendicular to at least a portion of the upper surface of the pedestal. The PVD chamber includes a lid assembly includes a first target and a second target. A first surface of the first target defines a first zone of the processing region, a center of the first surface a first distance from a plane of the upper surface of the pedestal. A second surface of the second target defines a second zone of the processing region, a center of the second surface a second distance from the plane of the upper surface of the pedestal. The PVD chamber includes a system controller that is configured to simultaneously control a first voltage bias for the first target and a second voltage bias for the second target.

In one embodiment, a PVD chamber includes a pedestal disposed within a processing region of the PVD chamber. The pedestal has an upper surface that is configured to support a workpiece thereon. The PVD chamber includes a first motor is coupled to the pedestal, the first motor configured to rotate the pedestal about a first axis that is perpendicular to at least a portion of the upper surface of the pedestal. The PVD chamber includes a lid assembly includes a first target and a second target. A first surface of the first target defines a first zone of the processing region, a center of the first surface a first distance from a plane of the upper surface of the pedestal. A second surface of the second target defines a second zone of the processing region, a center of the second surface a second distance from the plane of the upper surface of the pedestal. The PVD chamber includes a computer readable medium storing instructions. The instructions, when executed by a processor of a system that includes the PVD chamber, cause the system to simultaneously control a first voltage bias for the first target and a second voltage bias for the second target.

Embodiments of the disclosure may further include a method for perform PVD. The method includes rotating a workpiece disposed on an upper surface of a pedestal that is configured to support the workpiece thereon, the pedestal disposed within a processing region of the PVD chamber. The method also includes sputtering material from a first target onto the workpiece during rotation in a first zone of the processing region and material from a second target onto the workpiece during the rotation in a second zone of the processing region. The method also includes simultaneously controlling a first voltage bias for the first target during sputtering the material from the first target and a second voltage bias for the second target during sputtering the material from the second target. The center of a first surface of the first target is a first distance from a plane of the upper surface, and a center of a second surface of the second target is a second distance from a plane of the upper surface.

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

DETAILED DESCRIPTION

Embodiments of the disclosure provided herein generally relate to physical vapor deposition (PVD) of thin films on workpieces in an electronic device fabrication process. More particularly, embodiments described herein provide apparatus and methods for improving film deposition uniformity for high aspect ratio features of or in a workpiece, such as a substrate or interposer, which are commonly used in the packaging of integrated circuit containing devices. In some embodiments, the apparatus may include two or more targets that are configured to deposit the same material but are differently configured to achieve different sputtering profiles to provide different deposited film characteristics. In some embodiments, the apparatus may include two or more targets that are configured to deposit different materials. In one example, a first target may be oriented and positioned a first distance away from the workpiece and have a first bias applied during processing, resulting in a first distribution of sputtered material provided from the first target, and a second target may be oriented and positioned a second distance away from the workpiece and have a second bias applied during processing, resulting in a second distribution of sputtered material provided from the second target. The first distribution of sputtered material may be controlled to be relatively narrower in profile (e.g., over cosine distribution), higher in ionization energy, or both, and provide for relatively greater step coverage while the second distribution of sputtered material may be controlled to be relatively broader in profile (e.g., under cosine distribution), lower in ionization energy, or both, and provide for relatively more uniform coverage across the workpiece. Moreover, the use of two or more cathodes (e.g., multiple sputtering sources or targets) using the same target material provides increased process flexibility. A greater number of parameters may be adjusted and balanced, for example to balance the uniformity of coverage, step coverage, deposition throughput, or other characteristics of the deposited layers. Such parameters may include the voltage bias to the target (direct current (DC) bias, pulsed DC bias, or radio frequency (RF) bias), magnetron scanning profiles, magnetic confinement adapter levels and shaping, distance between target and workpiece to affect a throw distance, and relative angles between the targets and workpiece.

Exemplary Workpiece Processing System

FIG.1is a schematic top view of an exemplary workpiece processing system100(also referred to as a “processing platform”), according to certain embodiments. In certain embodiments, the workpiece processing system100is particularly configured for processing workpieces that include high aspect ratio features, such as high aspect ratio vias as described herein. In one or more embodiments, the workpiece is a substrate, such as a silicon or other semiconductor substrate, or an interposer such as an organic material containing interposer or glass interposer. The processing system100generally includes an equipment front-end module (EFEM)102for loading workpieces into the processing system100, a first load lock chamber104coupled to the EFEM102, a transfer chamber106coupled to the first load lock chamber104, and a plurality of other chambers coupled to the transfer chamber106as described in detail below. The EFEM102generally includes one or more robots105that are configured to transfer workpieces from the FOUPs103to at least one of the first load lock chamber104or the second load lock chamber120. Proceeding counterclockwise around the transfer chamber106from the first load lock chamber104, the processing system100includes a first dedicated degas chamber108, a first pre-clean chamber110, a first deposition chamber112, a second pre-clean chamber114, a second deposition chamber116, a second dedicated degas chamber118, and a second load lock chamber120. In certain embodiments, the transfer chamber106and each chamber coupled to the transfer chamber106are maintained at a vacuum state. As used herein, the term “vacuum” may refer to pressures less than 760 Torr, and will typically be maintained at pressures near 10−5Torr (i.e., ˜10−3Pa). However, some high-vacuum systems may operate below near 10−7Torr (i.e., ˜10−5Pa). In certain embodiments, the vacuum is created using a rough pump and/or a turbomolecular pump coupled to the transfer chamber106and to each of the one or more process chambers (e.g., process chambers108-118). However, other types of vacuum pumps are also contemplated.

In certain embodiments, workpieces are loaded into the processing system100through a door (also referred to as an “access port”), in the first load lock chamber104and unloaded from the processing system100through a door in the second load lock chamber120. In certain embodiments, a stack of workpieces is supported in a cassette disposed in the FOUP, and are transferred therefrom by a robot105to the first load lock chamber104. Once vacuum is pulled in the first load lock chamber104, one workpiece at a time is retrieved from the first load lock chamber104using a robot107located in the transfer chamber106. In certain embodiments, a cassette is disposed within the first load lock chamber104and/or the second load lock chamber120to allow multiple workpieces to be stacked and retained therein before being received by the robot107in the transfer chamber106or robot105in the EFEM102. However, other loading and unloading configurations are also contemplated.

Pre-cleaning of the workpieces is important to remove impurities, such as oxides, from the workpiece surface, so that films (e.g., metal films) deposited in the deposition chambers are not electrically insulated from the electrically-conductive metal surface area of the workpiece by the layer of impurities. By performing pre-cleaning in the first pre-clean chamber110and second pre-clean chamber114, which share the vacuum environment similar to the first deposition chambers112and second deposition chamber116, the workpieces can be transferred from the cleaning chambers to the deposition chambers without being exposed to atmosphere. This prevents formation of impurities on the workpieces during the transfer. In addition, vacuum pump-down cycles are reduced since a vacuum is maintained in the processing system100during transfer of the cleaned workpieces to the deposition chambers. In some embodiments, when a cassette is empty or full in the first load lock chamber104or the second load lock chamber120the processing system100may cause either of the load lock chambers to break vacuum so that one or more workpiece can be added or removed therefrom.

In certain embodiments, only one workpiece is processed within each pre-clean and deposition chamber at a time. Alternatively, multiple workpieces may be processed at one time, such as four to six workpieces. In such embodiments, the workpieces may be disposed on a rotatable pallet within the respective chambers. In certain embodiments, the first pre-clean chamber110and second pre-clean chamber114are inductively coupled plasma (ICP) chambers for etching the workpiece surface. However, other types of pre-clean chambers are also contemplated. In certain embodiments, one or both of the pre-clean chambers are replaced with a film deposition chamber that is configured to perform a PVD, chemical vapor deposition (CVD), or atomic layer deposition (ALD) process, such as deposition of silicon nitride.

In a pre-clean chamber that includes an ICP source, a coil at the top of the chamber is energized with an external RF source to create an excitation field in the chamber. A pre-clean gas (e.g., argon, helium) flows through the chamber from an external gas source. The pre-clean gas atoms in the chamber are ionized (charged) by the delivered RF energy. In some embodiments, the workpiece is biased by a RF biasing source. The charged atoms are attracted to the workpiece resulting in the bombardment and/or etching of the workpiece surface. Other gases besides argon may be used depending on the desired etch rate and the materials to be etched.

In certain embodiments, the first deposition chambers112and second deposition chamber116are PVD chambers. In such embodiments, the PVD chambers may be configured to deposit copper, titanium, aluminum, gold, and/or tantalum. However, other types of deposition processes and materials are also contemplated.

Exemplary PVD Chamber and Method of Use

FIG.2Ais a side cross-sectional view of a PVD chamber200that may be used in the processing system100ofFIG.1, according to certain embodiments. The PVD chamber200enables co-sputtering from two or more different targets at the same time. The PVD chamber200may utilize two or more different targets that are formed of the same material for co-sputtering, for example of high aspect ratio features.

FIG.2Awas formed by the application of the sectioning line applied to the top view of the PVD chamber200shown inFIG.2B. For example, the PVD chamber200may represent either one of the first deposition chamber112or second deposition chamber116shown inFIG.1. Alternatively, the PVD chamber200may represent an additional deposition chamber, not shown.FIG.2Bis an enlarged top cross-sectional view of an upper portion of the PVD chamber200ofFIG.2A, according to certain embodiments.FIGS.2C and2Dare enlarged views of portions of the PVD chamber ofFIG.2A, according to certain embodiments.FIGS.2A-2Dare, therefore, described together herein for clarity.

The PVD chamber200generally includes a chamber body202, a lid assembly204coupled to the chamber body202, an optional magnetic confinement adapter240coupled to the lid assembly204, a magnetron208coupled to the lid assembly204, an optional magnetic confinement adapter340coupled to the lid assembly204, a magnetron308coupled to the lid assembly204, a pedestal210disposed within the chamber body202, a target212disposed between the magnetron208and the pedestal210, and a target312disposed between the magnetron308and the pedestal210. During processing, the interior of the PVD chamber200, or processing region237, is maintained at a vacuum pressure. The processing region237is generally defined by the chamber body202and the lid assembly204, such that the processing region237is primarily disposed between the target212, the target312, and the workpiece supporting surface214of the pedestal210. A first zone238of the processing region237is generally defined by the zone of the processing region237that is primarily disposed between the target212and the workpiece supporting surface214of the pedestal210. A second zone239of the processing region237is generally defined by the zone of the processing region237that is primarily disposed between the target312and the workpiece supporting surface214of the pedestal210.

A power source206is electrically connected to the target212to apply a negatively biased voltage to the target212(e.g., a first voltage bias). A power source207is electrically connected to the target312to apply a negatively biased voltage to the target312(e.g., a second voltage bias). In certain embodiments, the power source206is either a straight DC mode source or a pulsed DC mode source, and the power source207is either a straight DC mode source or a pulsed DC mode source. However, other types of power sources are also contemplated, such as radio frequency (RF) sources. Power source206and power source207may be independently or jointly controlled, such as by system controller250.

The target212includes a target material212M and a backing plate218, and is part of the lid assembly204. A front surface of the target material212M of the target212defines a portion of the processing region237, and in particular at least a portion of the first zone238. The backing plate218is disposed between the magnetron208and target material212M of the target212, wherein, in some embodiments, the target material212M is bonded to the backing plate218. Typically, the backing plate218is an integral part of the target212and thus for simplicity of discussion the pair may be referred to collectively as the “target.” The backing plate218is electrically insulated from the support plate213of the lid assembly204by use of a support, which may include a support plate213, an electrical insulator215, and a shield223. The electrical insulator215prevents an electrical short being created between the backing plate218and the support plate213of the grounded lid assembly204. A shield223is coupled to the support plate213. The shield223prevents material sputtered from the target212from depositing a film on the support plate213. In some embodiments, the shield223may include a Faraday shield that is configured to allow magnetic fields generated by the target spacing adapters240and340to be provided to the first zone238and second zone239, respectively.

Similarly to target212, the target312includes a target material312M and a backing plate318, and is part of the lid assembly204. A front surface of the target material312M of the target312defines a portion of the processing region237, and in particular the second zone239.

As shown inFIG.2A, the backing plate218has a plurality of cooling channels233configured to receive a coolant (e.g., DI water) therethrough to cool or control the temperature of the target212. In certain embodiments, the backing plate218may have one or more cooling channels. In some examples, the plurality of cooling channels233may be interconnected and/or form a serpentine path through the body of the backing plate218. Similarly, backing plate318may have a plurality of of cooling channels, or one or more cooling channels.

In some embodiments, the magnetron208and target212, which includes the target material212M and backing plate218, each have a triangular or delta shape, such that a lateral edge of the target212includes three corners (e.g., three rounded corners shown inFIG.2B-2C). As illustrated inFIG.2B, the target212is oriented such that a tip of a corner of the triangular or delta shaped target is at or adjacent to the center axis291. When viewed in a planar orientation view, as shown inFIG.2B, the surface area of the target212is less than the surface area of the workpiece216. In some embodiments, a surface area of the upper surface of the pedestal is greater than a surface area of the front surface of the target212. In some embodiments, the ratio of the surface areas of the front surface of the target212to the deposition surface of the workpiece216(e.g., upper surface of the workpiece) is between about 0.1 and about 0.4.

Likewise, the magnetron308and target312may also each have a triangular or delta shape. In one or more embodiments, the magnetron208may have the same dimensions, shape, or both as the magnetron308, and the target212may have the same dimensions, shape, or both as the target312. In one or more embodiment, the magnetron208and the magnetron308may have different dimensions, different shape, or both. The target212may have different dimensions, different shape, or both, from the target312.

As shown inFIG.2A, the magnetron208and the magnetron308is disposed over a portion of the target212and the target312, respectively, and in a region of the lid assembly204that is maintained at atmospheric pressure. The magnetron208includes a magnet plate209(or yoke) and a plurality of permanent magnets (not shown) attached to the shunt plate. Likewise, the magnetron308includes a magnet plate309(or yoke) and a plurality of permanent magnets (not shown) attached to the shunt plate. The magnet plate209and magnet plate309have triangular or delta shapes with three corners. The magnets of the magnet plate209and magnet plate309are permanent magnets arranged in one or more closed loops. Each of the one or more closed loops will include magnets that are positioned and oriented relative to their pole (i.e., north (N) and south (S) poles) so that a magnetic field spans from one loop to the next or between different portions of a loop. The sizes, shapes, magnetic field strength and distribution of the individual magnets are generally selected to create a desirable erosion pattern across the surface of the target212and target312when used in combination with oscillation of the magnetron208and the magnetron308. In certain embodiments, the magnetron208, magnetron308, or both, may include a plurality of electromagnets in place of the permanent magnets.

The pedestal210has an upper surface214supporting a workpiece216. A clamp224is used to hold the workpiece216on the upper surface214. In certain embodiments, the clamp224operates mechanically. For example, the weight of the clamp224may hold the workpiece216in place. In certain embodiments, the clamp224is lifted by pins that are movable relative to the pedestal210to contact an underside of the clamp224.

In this example, the backside of the workpiece216is in contact with the upper surface214of the pedestal210. In some examples, the entire backside of the workpiece216may be in electrical and thermal contact with the upper surface214of the pedestal210. The temperature of the workpiece216may be controlled using a temperature control system232. In certain embodiments, the temperature control system232has an external cooling source that supplies coolant to the pedestal210. In some embodiments, the external cooling source is configured to deliver a cryogenically cooled fluid (e.g., Galden®) to heat exchanging elements (e.g., coolant flow paths) within a workpiece supporting portion of the pedestal210that is adjacent to the upper surface214, in order to control the temperature of the workpiece to a temperature that is less than 20° C., such as less than 0° C., such as about −20° C. or less. In certain embodiments, the temperature control system232includes a heat exchanger and/or backside gas flow within the pedestal210. In some examples, the cooling source may be replaced or augmented with a heating source to increase the workpiece temperature independent of the heat generated during the sputtering process. Controlling the temperature of the workpiece216is important during the sputtering process to obtain a predictable and reliable thin film. In certain embodiments, a RF bias source234is electrically coupled to the pedestal210to bias the workpiece216during the sputtering process. Alternatively, the pedestal210may be grounded, floated, or biased with only a DC voltage source. Biasing the workpiece216can improve film density, adhesion, and material reactivity on the workpiece surface.

A pedestal shaft221is coupled to an underside of the pedestal210. A rotary union219is coupled to a lower end of the pedestal shaft221to provide rotary fluid coupling with the temperature control system232and rotary electrical coupling with the RF bias source234. In certain embodiments, a copper tube is disposed through the pedestal shaft221to couple both fluids and electricity to the pedestal210. The rotary union219includes a magnetic liquid rotary sealing mechanism (also referred to as a “Ferrofluidic® seal”) for vacuum rotary feedthrough.

In one example, the workpiece216is a square or rectangular panel. In certain embodiments, the upper surface214of the pedestal210fits a single square or rectangular panel workpiece having sides of about 500 mm or greater, such as 510 mm by 515 mm or 600 mm by 600 mm. However, apparatus and methods of the present disclosure may be implemented with many different types and sizes of workpieces.

In certain embodiments, the pedestal210is rotatable about a center axis291perpendicular to at least a portion of the upper surface214of the pedestal210. In this example, the pedestal210is rotatable about a vertical axis, which corresponds to the z-axis. In certain embodiments, rotation of the pedestal210is continuous without indexing. In other words, a motor231driving rotation of the pedestal210does not have programmed stops for rotating the workpiece216to certain fixed rotational positions. Instead, the pedestal210is rotated continuously in relation to the target212to improve film deposition uniformity. In certain embodiments, the motor231is an electric servo motor. The motor231may be raised and lowered by a separate motor215. The motor215may be an electrically powered linear actuator. A bellows217surrounds the pedestal shaft and forms a seal between the chamber body202and the motor231during raising and lowering of the pedestal210.

An underside surface of the target212, which is defined by a surface of a target material212M, faces towards the upper surface214of the pedestal210and towards a front side of the workpiece216. An underside surface of the target312, which is defined by a surface of a target material312M, also faces towards the upper surface214of the pedestal210and towards a front side of the workpiece216. The underside surface of the target212faces away from the backing plate218, which faces towards the atmospheric region or external region of the PVD chamber. Similarly, the underside surface of the target312faces away from the backing plate318, which faces towards the atmospheric region or external region of the PVD chamber. In certain embodiments, the target materials212M of the target212and target materials312M of the target312are formed from a metal for sputtering a corresponding film composition on the workpiece216. In one example, the target materials212M and target materials312M may include a pure material or alloy containing elements selected from the group of copper (Cu), molybdenum (Mo), nickel (Ni), titanium (Ti), tantalum (Ta), aluminum (Al), cobalt (Co), gold (Au), silver (Ag), manganese (Mn), and silicon (Si). The materials deposited on a workpiece216by the methods described herein may include pure metals, doped metals, metal alloys, metal nitrides, metal oxides, metal carbides containing these elements, as well as silicon containing oxides, nitrides or carbides.

In the illustrated embodiments, a plane that is parallel to the underside of the target212is tilted in relation to an upper surface of the support plate213by a first angle as shown inFIG.2A. In other words, the plane of the target212is tilted in relation to a plane of the upper surface214of the pedestal210and, thus, in relation to the front side of the workpiece216. Because respective bodies of each of the pedestal210and the target212are generally planar, the target212may also be referred to as being tilted relative to the pedestal210, and vice versa. In certain embodiments, the angle is about 2° to about 10°, such as about 3° to about 5°. As shown inFIG.2A, the angle is about 4°. As shown inFIG.2A, the target212is tilted downward in a direction from an inner radial edge212C of the target212to an outer radial edge212A of the target212. The inner radial edge212C is farther from the upper surface214of the pedestal210(e.g., vertically) compared to the outer radial edge212A. In one example, a target212includes an edge that includes three corners, and one of the three corners, which is coincident with the inner radial edge212C, is positioned farther from the upper surface of the pedestal210as compared to each of the two other corners due to the formed tilt angle. It is believed that tilt angles above the range provided herein may have target-to-workpiece spacing that varies too much from the inner radial edge212C to the outer radial edge212A, which can result in undesirable variation in film deposition uniformity and/or quality. In one example, an undesirable variation in film quality will include an undesirable variation in film roughness or grain size, or workpiece center-to-edge uniformity. In another example, the undesirable variation in film quality can include an undesirable ratio of the amount of sputtered material provided to the surface of the workpiece versus the amount of sputtered material provided to the shields that surround the workpiece during a PVD process. Tilt angles below the range provided herein cause undesirable non-uniformity of the film. Therefore, the tilt angle window provided herein is able to achieve film deposition results that are improved over other conventional designs. The above description for target212may be applied to the target312relative to a plane of the upper surface214of the pedestal210and, thus, in relation to the front side of the workpiece216.

In this example, the pedestal210is substantially horizontal, or parallel to the x-y plane, whereas the target212and the target312is non-horizontal, or tilted in relation to the x-y plane. However, other non-horizontal orientations of the pedestal210are also contemplated.

In the illustrated embodiments, the target spacing adapter240is coupled to the lid assembly204. The target spacing adapter240is generally cylindrically shaped, enclosing a volume that is disposed below the target212and magnetron208and above the upper surface214of pedestal210, including at least a portion of the first zone238of the processing region237. The target spacing adapter340is also coupled to the lid assembly204. The target spacing adapter340is also generally cylindrically shaped, enclosing a volume that is disposed below the target312and magnetron308and above the upper surface214of pedestal210, including at least a portion of the second zone239of the processing region237. The target spacing adapter240and target spacing adapter340each have a plurality of cooling channels242and cooling channels342configured to receive a coolant (e.g., DI water) therethrough to cool or control the temperature of the target spacing adapter240and the target spacing adapter340. In some examples, the plurality of cooling channels242may be interconnected and/or form a serpentine path through the target spacing adapter240. Similarly, the plurality of cooling channels342may be interconnected and/or form a serpentine path through the target spacing adapter340.

In some embodiments, the target spacing adapter240and/or target spacing adapter340each include a magnetic confinement adapter, such as a magnetic confinement assembly241and magnetic confinement assembly341, respectively, as illustrated inFIGS.2C and2D, respectively. The magnetic confinement assembly241is generally disposed between the target212and the pedestal210, and is configured about a first center axis245of the first zone238. The first center axis245passes through the target212and the upper surface214of pedestal210. The magnetic confinement assembly341is generally disposed between the target312and the pedestal210, and is configured about a second center axis345of the second zone239. The second center axis345passes through the target312and the upper surface214of pedestal210. The magnetic confinement assembly241and magnetic confinement assembly341each include a plurality of permanent magnets243,343, or one or more inductive coils (not shown), that surround at least a portion of the target spacing adapter240and first zone238, and target spacing adapter340and second zone239, respectively. The plurality of permanent magnets243,343within the magnetic confinement assembly241and magnetic confinement assembly341are each configured to create static or dynamic magnetic fields within at least the first zone238and second zone239. The magnetic fields are configured to modify the shape of the plasma, concentration of plasma generated ions (e.g., gas and sputtered material) to control a density profile of the plasma and ionized sputtered atoms within the process volume237. In one example, the magnetic confinement assembly241and magnetic confinement assembly341are configured to separately adjust the radial distribution of the generated plasma and ionized sputtered atoms over the surface of the workpiece. In one embodiment, the magnetic confinement assembly241and magnetic confinement assembly341each include a rotational magnetic holder245and345that are configured to rotate about a center axis of the process first zone238and second zone239, respectively. In one or more embodiments, the rotational magnetic holder245, including a motor for the rotational magnetic holder245, is closer to the center axis291of the chamber204than illustrated forFIG.2A.

In some embodiments, the plurality of permanent magnets243,343, or one or more inductive coils, are aligned and/or oriented relative to a plane that is parallel to the surface of the target212,312(e.g., lower surface of target material212M,312M), such that the generated field(s) are properly aligned to allow for uniform deposition on a substrate. In this case, the central axes of each of the plurality of permanent magnets243,343, or one or more inductive coils, are aligned such that they positioned at an angle relative to a vertical direction (i.e., Z-direction).

A system controller250, such as a programmable computer, is coupled to the PVD chamber200for controlling the PVD chamber200or components thereof. For example, the system controller250may control the operation of the PVD chamber200using direct control of the power source206, the magnetron208, the magnetron308, the target spacing adapter240, cooling of the target spacing adapter240, the target spacing adapter340, cooling of the target spacing adapter340, the pedestal210, cooling of the backing plate218, the first actuator220, the second actuator222, the temperature control system232, and/or the RF bias source234, or using indirect control of other controllers associated therewith. In operation, the system controller250enables data acquisition and feedback from the respective components to coordinate processing in the PVD chamber200.

The system controller250includes a programmable central processing unit (CPU)252, which is operable with a memory254(e.g., non-volatile memory) and support circuits256. The support circuits256(e.g., cache, clock circuits, input/output subsystems, power supplies, etc., and combinations thereof) are conventionally coupled to the CPU252and coupled to the various components of the PVD chamber200.

In some embodiments, the CPU252is one of any form of general purpose computer processor used in an industrial setting, such as a programmable logic controller (PLC), for controlling various monitoring system component and sub-processors. The memory254, coupled to the CPU252, is non-transitory and is typically one or more of readily available memory such as random access memory (RAM), read only memory (ROM), floppy disk drive, hard disk, or any other form of digital storage, local or remote.

Herein, the memory254is in the form of a computer-readable storage media containing instructions (e.g., non-volatile memory), that when executed by the CPU252, facilitates the operation of the PVD chamber200. The instructions in the memory254are in the form of a program product such as a program that implements the methods of the present disclosure (e.g., middleware application, equipment software application, etc.). The program code may conform to any one of a number of different programming languages. In one example, the disclosure may be implemented as a program product stored on computer-readable storage media for use with a computer system. The program(s) of the program product define functions of the embodiments (including the methods described herein).

Illustrative computer-readable storage media include, but are not limited to: (i) non-writable storage media (e.g., read-only memory devices within a computer such as CD-ROM disks readable by a CD-ROM drive, flash memory, ROM chips or any type of solid-state non-volatile semiconductor memory) on which information is permanently stored; and (ii) writable storage media (e.g., floppy disks within a diskette drive or hard-disk drive or any type of solid-state random-access semiconductor memory) on which alterable information is stored. Such computer-readable storage media, when carrying computer-readable instructions that direct the functions of the methods described herein, are embodiments of the present disclosure.

In operation, the PVD chamber200is evacuated, back filled with argon gas and maintained at a vacuum pressure by a vacuum pump (not shown). The power source206applies a negative bias voltage to the target212to generate an electric field inside the chamber body202. The electric field acts to attract gas ions, which due to their collision with the exposed surface of the target212, generates electrons that enable a high-density plasma to be generated and sustained near the underside of the target212, and ballistically causes the target material212M to be ejected from the target's surface. The plasma is concentrated near the surface of target material212M due to the magnetic field produced by the magnetron208. The magnetic field forms a closed-loop annular path acting as an electron trap that reshapes the trajectories of the secondary electrons ejected from the target material212M into a cycloidal path, greatly increasing the probability of ionization of the sputtering gas within the confinement zone. The plasma confined near the underside of the target212contains argon atoms, positively charged argon ions, free electrons, and neutral atoms (i.e., unionized atoms) sputtered from the target material212M. The argon ions in the plasma strike the target surface and eject atoms of the target material, which are accelerated towards the workpiece216to deposit a thin film on the workpiece surface. As noted above, the magnetic confinement assembly241,341is used to create static magnetic fields, dynamic magnetic fields, or both.

Similarly, the power source307also applies a negative bias voltage to the target312to generate an electric field inside the chamber body202. The electric field acts to attract gas ions, which due to their collision with the exposed surface of the target312, generates electrons that enable a high-density plasma to be generated and sustained near the underside of the target312, and ballistically causes the target material312M to be ejected from the target's surface. The plasma is concentrated near the surface of target material312M due to the magnetic field produced by the magnetron308. The magnetic field forms a closed-loop annular path acting as an electron trap that reshapes the trajectories of the secondary electrons ejected from the target material312M into a cycloidal path, greatly increasing the probability of ionization of the sputtering gas within the confinement zone. The plasma confined near the underside of the target312contains argon atoms, positively charged argon ions, free electrons, and neutral atoms (i.e., unionized atoms) sputtered from the target material312M. The argon ions in the plasma strike the target surface and eject atoms of the target material, which are accelerated towards the workpiece216to deposit a thin film on the workpiece surface. Similar to the magnetic confinement assembly241, the magnetic confinement assembly341is used to create static magnetic fields, dynamic magnetic fields, or both.

In operation, the system controller250can control the magnetron208, the magnetic confinement adapter240, or both, according to a first sputtering profile to affect the properties of the plasma associated with target212. And, the system controller250can control the magnetron308, the magnetic confinement adapter340, or both, according to a second sputtering profile to affect the properties of the plasma associated with target312. Control of the plasma associated with the targets can allow the tuning of the uniformity and properties of the deposited film on the workpiece. The system control250can control the deposition angle, deposition rate, and profile for the distribution of sputtered material ejected from target212separate from the deposition angle, deposition rate, material, and profile for the distribution of sputtered material of material ejected from the target312.

Inert gases, such as argon, are usually employed as the sputtering gas because they tend not to react with the target material or combine with any process gases and because they produce higher sputtering and deposition rates due to their relatively high molecular weight.

FIG.2Bis a top view illustrating an overlay of the targets212and312and the workpiece216in relation to the chamber body202ofFIG.2A, according to certain embodiments. In certain embodiments, the outer radial edge212A,312A of the target212, and similarly target312, extends a distance of about 1 inch to about 3 inches, such as about 1.5 inches beyond a corner of the workpiece216. In certain embodiments, the inner radial edge212C of the target212is spaced a distance of about 0.25 inches to about 0.75 inches, such as about 0.5 inches from the center axis291, which may be coincident with a radial center of the chamber body202. Similarly, the inner radial edge312C of the target312is spaced a distance of about 0.25 inches to about 0.75 inches, such as about 0.5 inches from the center axis291.

As shown inFIG.2B, one or more of the target212, target material212M and backing plate218each have a triangular or delta shape that has three rounded corners, wherein one of the three rounded corners is positioned near or substantially adjacent to the center axis291, and the magnetron208has a round shape. In one or more embodiments, for example as illustrated with referenceFIG.4below, the magnetron has a triangular or delta shape similar to but smaller than the target212and backing plate218. The target212and magnetron208are shaped and oriented such that the magnetron208is able to be translated over substantially the entire active area of the target212, such as the target material212M portion of the target212. In some embodiments, the target212and magnetron208have substantially the same shape as described in more detail below. Similarly, as shown inFIG.2B, one or more of the target312, target material312M and backing plate318each have a triangular or delta shape that has three rounded corners, wherein one of the three rounded corners is positioned near or substantially adjacent to the center axis291, and the magnetron308has a round shape. In one or more embodiments, the magnetron308has a triangular or delta shape similar to the magnetron408illustrated with reference toFIG.4. The target312and magnetron308are shaped and oriented such that the magnetron308is able to be translated over substantially the entire active area of the target312, such as the target material312M portion of the target312. In some embodiments, the target312and magnetron308have substantially the same shape as described in more detail below.

Exemplary Sputtering Profile and Method of Use

FIG.3illustrates a schematic cross-sectional view300of sputter profiles generated by a first cathode304and a second cathode306for features formed in a workpiece216that include high aspect ratio features. Cross-sectional view300includes representative features302of a workpiece, distribution of sputtered material330, the first cathode304and the second cathode306. In one or more embodiments, features302may be exemplary features of the workpiece216disposed on the upper surface214of the pedestal210.

In one or more embodiments, first cathode304may be or include at least the target212and second cathode306may be or include at least the target312. In one or more embodiments, the target material212M of the first cathode304and the target material312M of the second cathode306are composed of a same material. In some embodiments, the target material212M may be composed of a different material than the target material312M. In some embodiments, the target material is copper (Cu). In one or more embodiments the same material may be a pure material or alloy containing elements selected from the group of copper (Cu), molybdenum (Mo), nickel (Ni), titanium (Ti), tantalum (Ta), aluminum (Al), cobalt (Co), gold (Au), silver (Ag), manganese (Mn), and silicon (Si).

As further described herein, the first cathode304is disposed closer to (with less distance from) the upper surface214of the pedestal210, and thus closer to the workpiece, than the second cathode306, as shown by the distances304A and306A, which are measured from a center or centroid of the respective cathode.

In one or more embodiments, the features302are formed on a substrate, such as a glass substrate or semiconductor substrate. In some embodiments, the features302may be of another type of workpiece, for example an interposer (e.g., glass interposer or organic interposer). Features302include features closer to a first edge of the workpiece216(including feature324), features closer to a center of the workpiece216(including feature326), and features closer to a second edge of the workpiece216(including feature328). A position of features302will change over time relative to the first cathode304and the second cathode306as workpiece216is rotated about a central axis (e.g., center line CL inFIG.3. For example, at one instant in time (as illustrated inFIG.3) some features are closer to an edge of the workpiece216that is closer to the first cathode304(including feature324), some features are closer to a center of the workpiece216that are generally between the first cathode304and the second cathode306(including feature326), and some features are closer to an edge of the workpiece216that is closer to the second cathode306(including feature328). At another instant in time (not shown) the features (including feature324) that were closer to the first cathode304at the first instant in time are now closer to the second cathode306, the features that were closer to the center of the workpiece216are still near the center, and the features (including feature328) that were closer to the second cathode306at the first instant in time are now closer to the first cathode304.

In one or more embodiments, features302may be high aspect ratio features. High aspect ratio features include features whose depth exceeds the width, and in particular where the depth exceeds the width by at least a ratio of 2:1. In some embodiments, the depth exceeds the width by at least 5:1, and may be as high as 10:1. In one or more embodiments, the features302may have a ratio of depth to width that exceeds 10:1. In one or more embodiments high aspect ratio features include vias.

During operation of a PVD chamber that includes the first cathode304and the second cathode306(e.g., the PVD chamber200), features302can be simultaneously exposed to two different distributions of sputtered materials330from the first cathode304and the second cathode306. Feature324is simultaneously exposed to a distribution of sputtered material332from the first cathode304and a distribution of sputtered material334from the second cathode306to form the seed layer320of feature324. Similarly, feature326is simultaneously exposed to the distribution of sputtered material332from the first cathode304and the distribution of sputtered material334from the second cathode306to form the seed layer320of feature326, and feature328is simultaneously exposed to the distribution of sputtered material332from the first cathode304and the distribution of sputtered material334from the second cathode306to form the seed layer320of feature326.

In some embodiments, the first cathode304and the second cathode306have different sputtering profiles. In one or more embodiments, the sputtering profile associated with the first cathode304and the second cathode306depends on the throw distance, the first deposition angle of the target relate to the workpiece, chamber pressure, magnetic field generated by the magnetrons positioned adjacent to the cathodes304,306, and the DC or RF power provided to each of the cathodes304,306. The sputtering profile can also be adjusted by the magnetic fields generated by the magnetic confinement assemblies. As such, the first cathode304may be associated with a first throw distance, a first deposition angle, and a first DC or RF power applied to the first cathode304, and the second cathode306may be associated with a second throw distance, a second deposition angle, and a second DC or RF power applied to the second cathode306. As discussed herein, the first cathode304is a different distance from the workpiece that includes features302than the second cathode306, providing different throw distances (e.g., distances304A and306A). The first cathode304and the second cathode306can be tilted with different angles with reference to the workpiece (e.g., substrate, interposer, or other workpiece), and those can have different deposition angles. Moreover, one or more of the magnetron208, the magnetic confinement adapter240, or angle of the first cathode304, may be controlled (e.g., by system controller250) to control or otherwise affect the first sputtering profile; and one or more of the magnetron308, the magnetic confinement adapter340, or angle of the second cathode306, may be controlled (e.g., by system controller250) to control or otherwise affect the second sputtering profile. A first ion energy distribution may be controlled or otherwise affected (e.g., using system controller250) by controlling one or more of the magnetron208, the magnetic confinement adapter240, or a bias of the power source206. A second ion energy distribution may be controlled or otherwise affected (e.g., using system controller250) by controlling one or more of the magnetron308, the magnetic confinement adapter340, or a bias of the power source207.

The distribution of sputtered material332and the distribution of sputtered material334may impinge on feature324at different angles, due to a difference in throw distances, attributes of the magnetrons208,308, and with different ion or neutral energies of the sputtered materials due at least in part to the power applied to the cathodes304and306. In one or more embodiments, the distribution of sputtered material334associated with the second cathode306may have (e.g., and be controlled to have) a relatively more narrow profile than the distribution of sputtered material332associated with the first cathode304. The more narrow profile is associated with a relatively higher applied power, and provides a relatively greater amount of sputtered material deeper into feature324. Conversely the distribution of sputtered material332is a relatively broader profile than the distribution of sputtered material334, and is associated with a relatively lower applied power, and provides a relatively greater amount of sputtered material across the workpiece (e.g., has increased uniformity relative to the narrower profile associated with distribution of sputtered material334) and relatively increased step coverage (e.g., relative to distribution of sputtered material334).

Similarly, the distribution of sputtered material332and the distribution of sputtered material334may impinge on feature326at different angles, from different throw distances, and with different applied bias powers. And, the distribution of sputtered material332and the distribution of sputtered material334may impinge on feature328at different angles, from different throw distances, and with different ion energies.

In one or more embodiments, one or more of the magnetron208(a first magnetron) or the magnetron308(a second magnetron) may be simultaneously controlled (e.g., by system controller250) during sputtering of the target material212M from the target212and during sputtering of the target material312M from the target312, respectively. The magnetron208may be controlled according to a first scanning pattern and the magnetron308may be controlled according to a second scanning pattern. In one or more embodiments, the scanning pattern of magnetron208may include translation in the x-axis and y-axis directions over the target212during sputtering to provide to control erosion of the target212, and the scanning pattern of magnetron308may include translation in the x-axis and y-axis directions over the target312during sputtering to provide to control erosion of the target312. In one or more embodiments, the scanning pattern of magnetron208may include translation in the circumferential and radial directions over the target212during sputtering to provide to control erosion of the target212, and the scanning pattern of magnetron308may include translation in the circumferential and radial directions over the target312during sputtering to provide to control erosion of the target312.

Following operation of the PVD chamber to deposit the seed layer320of the features302of the workpiece, voids322may remain. Voids322may be later filled. In one or more embodiments, voids322may be filled with a same material as the seed layer320, for example using an electroplating process.

As illustrated inFIG.4, in one or more embodiments, a magnetron408has a triangular or delta shape that has three rounded corners, wherein one of the three rounded corners is positioned near or substantially adjacent to the center axis, in addition to the target212, target material212M and backing plate218that each have a triangular or delta shape that has three rounded corners. A radius R1of the magnetron408is less than a corresponding radius R2of the target212so that the magnetron408is able to translate in the x-axis and y-axis directions over the target212, for example as described above. In one or more embodiments, the magnetron408may alternatively translate in a radial direction. As shown inFIG.4, an outer radial edge408A of the magnetron408has a radius of curvature that is less than or equal to the corresponding outer radial edge212A of the target212. In some embodiments, the radii of curvature differ by about 40% or less, such as about 20% or less. An arc length of the outer radial edge408A of the magnetron408is less than a corresponding arc length of the outer radial edge212A of the target212. In one or more embodiments, the magnetron408is able to translate in the x-axis and y-axis directions over the target212, for example as described above. In one or more embodiments, the magnetron408may alternatively translate in a circumferential direction. As shown inFIG.4, respective opposite edges408B and408D of the magnetron408and corresponding opposite edges212B and212D of the target212are oriented close to parallel, respectively, to each other. In some embodiments, angles between the respective edges408B,212B and408D,212D are within a range of about 5° or less, such as about 0° to about 5°, such as about 0° (i.e., parallel to each other). Although not shown, a second magnetron that also has a triangular or delta shape that has three rounded corners may be similarly configured with reference to target312.

As further discussed above, the magnetron408may be translated in the x-axis and y-axis directions over the target, or in radial and circumferential directions, to scan the magnetron408along a scan path over target212. As shown inFIG.4, a first actuator (not shown) and a second actuator (not shown) can be synchronized to scan the magnetron408along a scan path426. Scan path426is provided for illustrative purposes only, and any number of different scan paths may scan the magnetron408over the active area of the target212consistent with the techniques described herein. Similarly, a first actuator (not shown) and second actuator (not shown) can be synchronized to scan a magnetron (not shown) along a scan path over the active area of the target312consistent with the techniques described herein.

FIG.5is a diagram illustrating a method500of processing a workpiece using a PVD chamber, according to certain embodiments. Note that PVD chamber200is described in the following example for illustrative purposes only.

At operation502, a workpiece is disposed on an upper surface of a pedestal that is configured to support the workpiece thereon, and the workpiece is rotated. The pedestal is disposed within a processing region of the PVD chamber. In some embodiments, with reference to PVD chamber200, the workpiece216is disposed on the upper surface214of the pedestal210that is configured to support the workpiece216thereon, and the workpiece216is rotated about a central axis (e.g., center line CL inFIG.3). The pedestal210is disposed within a processing region237of the PVD chamber200. In some embodiments, the pedestal210is rotated continuously in relation to the target212and target312to improve film deposition uniformity.

At operation504, material is sputtered from a first target a first distance from a plane of the upper surface onto the workpiece during rotation in a first zone of the processing region and material is sputtered from a second target a second distance from the plane of the upper surface onto the workpiece during the rotation in a second zone of the processing region. In some embodiments, the first target is a same material as the second target. In one or more embodiments, with reference to PVD chamber200, material is sputtered from the target212(a first target) a first distance from a plane of the upper surface214onto the workpiece216during rotation in the first zone238of the processing region237and material is sputtered from the target312(a second target) a second distance from the plane of the upper surface214onto the workpiece216during the rotation in the second zone239of the processing region237, and the target212is a same material as the target312. In some embodiments, the target212is a different material from the target312, and are configured to deposit different materials.

At operation506, a first voltage bias and a second voltage bias are simultaneously controlled, where the first voltage bias is for the first target during sputtering the material from the first target and the second voltage bias is for the second target during sputtering the material from the second target. In some embodiments, with reference to PVD chamber200, the first voltage bias from the power source206and a second voltage bias from the power source207are simultaneously controlled by system controller250. In one or more embodiments, the system controller causes the first voltage bias to be applied to the target212, which causes material to be sputtered from the target212, and causes the second voltage bias to be applied to the target312, which causes material to be sputtered from the target312. In one example, the first voltage bias applied to the target212is less than the second voltage bias applied to the target312. In another example, the throw distance of the target212is smaller than the throw distance of the target312. In another example, the magnetic field generated by the magnetic confinement assembly241associated with the target212is stronger than the magnetic field generated by the magnetic confinement assembly341associated with the target312, or vice versa. In another example, the throw distance of the target212is smaller than the throw distance of the target312, and the magnetic field generated by the magnetic confinement assembly241associated with the target212is less than the magnetic field generated by the magnetic confinement assembly341associated with the target312. Also in one example, or in one of these examples, the angular distribution of the sputtered material from the target212is narrower than the angular distribution of the sputtered material from the target312due to at least one of the adjustment of the bias power applied to the target212being greater than the bias power applied to the target312.

Additionally, in some embodiments of method500, operations502,504, and506are substantially performed simultaneously. In some embodiments of method500, operations502and506are initiated before operation504is initiated. In some embodiments of method500, operations502,504, and506are initiated in a sequential order. In some embodiments of method500, operations502,504, and506are initiated in a non-sequential order.