Patent Application
20250075309
Embodiments of the present subject matter generally relates to physical vapor deposition. More particularly, the subject matter relates to a sputtering target for use in a physical vapor deposition chamber and process.
Physical Vapor Deposition (PVD) is a crucial thin-film deposition technique extensively employed in semiconductor substrate processing to create thin layers of materials with enhanced properties. PVD operates under vacuum conditions and involves the evaporation or sputtering of target materials, such as metals or ceramics, onto a semiconductor substrate to form thin films. In sputtering, high-energy ions bombard the target material of the target assembly, dislodging atoms from a target that are then deposited onto the substrate. PVD is highly versatile, allowing for precise control over film thickness, uniformity, and composition, making it ideal for fabricating various semiconductor components, including integrated circuits, microelectromechanical systems (MEMS), and optical coatings. The deposited thin films provide essential functionalities, such as conductive layers for interconnections and diffusion barriers, and contribute to enhancing device performance, reliability, and miniaturization in modern semiconductor manufacturing processes.
The choice of target material is critical as it directly determines the properties and characteristics of the thin film being deposited. Different applications require different materials with specific properties. For example, semiconductor devices may require thin films made of metals like aluminum, molybdenum, copper, or tungsten for interconnects and thermal management, or dielectric materials like silicon dioxide or silicon nitride for insulating layers. Other specialized applications may demand exotic materials like magnetic alloys or refractory compounds. In all target material choices, throughput and target life are always a key consideration when reviewing a manufacturing process.
To ensure high-quality thin films, the target material must be pure and have a uniform composition. Additionally, the design of a target assembly, target life span, the shape and size of the target material, and the corresponding relations all influence the deposition process, as they influence the distribution, thickness of the deposited thin film on the substrate, and service life of the target assembly.
Therefore, there exists a need in the art for a sputtering target apparatus with an improved life span.
The disclosure relates to a target for physical vapor deposition processes. In one embodiment, a physical vapor deposition (PVD) target assembly, includes a monolithic target with a support region partially defined by a process face and radial sidewalls; and a recess within a mounting face of the monolithic target, the recess disposed opposite the process face and extending radially outward of the radial sidewalls.
In another embodiment, a PVD target assembly, includes a monolithic target with a support region partially defined by a process face and radial sidewalls; a mounting region disposed radially outward of the support region. The mounting region includes a mounting face and a channel. The mounting region includes an upper face disposed between the process face of the support region and the mounting face. The channel is disposed in the upper face. The PVD target assembly also includes a recess within a mounting face and is disposed opposite the process face and extends radially outward of the radial sidewalls.
In another embodiment, a PVD target assembly, includes a monolithic target with a support region partially defined by a process face and radial sidewalls; a mounting region disposed radially outward of the support region. The mounting region includes a mounting face and a channel. The mounting region includes an upper face disposed between the process face of the support region and the mounting face. The channel is disposed in the upper face. The PVD target assembly also includes a recess within a mounting face and is disposed opposite the process face and extends radially outward of the radial sidewalls. The recess also includes a recess diameter of about 90% of the PVD target diameter.
So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments of the disclosure and are therefore not to be considered limiting of its scope, as the disclosure may admit to other equally effective embodiments.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
Embodiments of target assemblies for use in substrate processing chambers, such as for a physical vapor deposition (PVD) system, are provided herein.
The chamber 101 includes a chamber body 102 having chamber walls that define a processing volume 104. The chamber 101 further includes a target 106 and a substrate support 116, disposed within the processing volume 104. The target 106 is described in more detail below.
The substrate support 116 is operable to secure (e.g., chuck) a substrate 115 to the substrate support 116. The substrate is disposed within the processing volume 104 during substrate processing operations. In some embodiments, the substrate support 116 includes an electrode 117 to chuck the substrate 115. In other embodiments the substrate support 116 uses vacuum to chuck the substrate 115.
The PVD system 100 further includes an RF power supply 108, a vacuum source 114, a controller 130, an auto capacitance tuner (ACT) 120, a power source 118, a reactive gas source 126, a sputter gas source 122, a DC power supply 110, and a magnetron assembly 111.
The target 106 can be coupled to the RF power supply 108 and the DC power supply 110. Power provided from RF power supply 108 and/or the DC power supply 110 to the target 106 can be used to ignite a plasma in the processing volume 104. The plasma is formed by a sputter gas. For example, the sputter gas may be argon (Ar), oxygen (O), hydrogen (H), fluorine (F), chlorine (Cl), any combination thereof. Other reactive gases are also contemplated. The plasma may be created in the processing volume 104 by a capacitive process, an inductive process, or other plasma generation methods.
The magnetron assembly 111 is disposed the above the substrate support 116. The magnetron assembly 111 directs magnetic fields within the processing volume 104 to regions around the target 106 in the processing volume 104. These magnetic fields can help increase a density of the plasma formed in the processing volume 104 around the target 106. In one embodiment, the magnetron assembly 111 can include one or more magnets 112 (e.g., strength magnets). The one or more magnets 112 may be arranged to provide a magnetic field which extends through the target 106 and into the processing volume 104. In some embodiments, the generated magnetic fields can trap electrons along magnetic field lines to increase the plasma ion density by enabling additional electron-gas atom collisions. The magnetron assembly 111 and the magnets 112 are adjustable to adjust the magnetic field within the process volume 104.
The vacuum source 114 is fluidly coupled to the processing volume 104. The vacuum source 114 is any device or assembly which may create a vacuum. For example, the vacuum source 114 is a vacuum pump. The vacuum source 114 maintains the processing volume 104 at a specified process pressure during processing operations. The vacuum source 114 also evacuates sputter gases, reactive gases, and other gases from the processing volume 104.
The power source 118 is coupled to the electrode 117 in the substrate support 116. The electrode 117 induces an electrical bias on the substrate 115. The power source 118 may be a RF or DC power source. In some embodiments, a self-bias may form on the substrate 115 during processing. In some embodiments, the electrode 117 may be coupled to the ACT 120. The ACT 120 is operable to adjust the capacitance (and thus impedance) from the substrate support 116 to a ground.
The reactive gas source 126 is fluidly connected to the processing volume 104. A reactive gas flow controller 128, such as a mass flow controller (MFC), may be disposed between a reactive gas source 126 and the process volume 104. The reactive gas flow controller 128 controls a flow of the reactive gas (e.g., oxygen) from the reactive gas source 126 to the processing volume 104.
The sputter gas source 122 is fluidly connected to the processing volume 104. A sputter gas flow controller 124, such as a MFC, may be disposed between the sputter gas source 122 and the processing volume 104. The sputter gas flow controller 124 controls a flow of the sputter gas (e.g., argon) from the sputter gas source 122 to the processing volume 104.
The chamber 101 further includes a controller 130. The controller 130 includes a programmable central processing unit (CPU) 130a which is operable with a memory 130b (e.g., non-volatile memory) and support circuits 130c. The support circuits are conventionally coupled to the CPU and comprise cache, clock circuits, input/output subsystems, power supplies, and the like, and combinations thereof coupled to the various components of PVD system 100, to facilitate control thereof. The CPU 130a is one of any form of general purpose computer processor used in an industrial setting, such as a programmable logic controller (PLC), for controlling various components and sub-processors of the processing system. The memory 130b, coupled to the CPU 130a, is non-transitory and is typically one or more of readily available memories 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.
Typically, the memory 130b is in the form of a non-transitory computer-readable storage media containing instructions (e.g., non-volatile memory), which when executed by the CPU 130a, facilitates the operation of PVD system 100. The instructions in the memory 130b are in the form of a program product such as a program that implements the methods of the present disclosure. 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 non-transitory 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 devices, e.g., solid state drives (SSD)) on which information may be 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 some embodiments, the methods set forth herein, or portions thereof, are performed by one or more application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other types of hardware implementations. In some other embodiments, the substrate processing and/or handling methods set forth herein are performed by a combination of software routines, ASIC(s), FPGAs and, or, other types of hardware implementations. One or more system controllers 130 may be used with one or any combination of the various systems described herein.
As used herein, ‘a CPU,” “a processor,” “at least one processor” or “one or more processors” generally refers to a single processor configured to perform one or multiple operations or multiple processors configured to collectively perform one or more operations. In the case of multiple processors, performance the one or more operations could be divided amongst different processors, though one processor may perform multiple operations, and multiple processors could collectively perform a single operation. Similarly, “memory,” “at least one memory,” or “or more memories” generally refers to a single memory configured to store data and/or instructions, multiple memories configured to collectively store data and/or instructions.
The target 106 includes a mounting region 207, recess 209, a channel 223, and a support region 253. The mounting region 207 is disposed radially outward of the support region 253. The mounting region 207 includes an upper face 221, a mounting face 205, an outer face 252, the channel 223, an extension length 225, and mounting thickness 201.
The outer face 252 is the radially outward face of the target 106 and defines a diameter of the target 106. The outer face 252 diameter is between about 15 inches to about 48 inches. For example, between about 18 inches and about 21 inches. For example, about 20 inches.
The extension length 225 is the distance between sidewalls 217 of the support region 253 and the outer face 252. The extension length 225 is about 2 inches to about 4 inches, for example about 3 inches.
The mounting thickness 201 is the distance between the upper face 221 and mounting face 205. The mounting thickness 201 is about 0.3 inches to about 0.7 inches, for example about 0.5 inches.
The mounting face 205 includes elements to mount the target 106 to the magnetron assembly 111. The elements of the mounting face 205 include one or more apertures, threaded holes, or other types of geometry to affix the target to the magnetron assembly 111.
The channel 223 is formed within the upper face 221 of the mounting region 207. In some embodiments, the channel 223 is disposed radially outward of the sidewalls 217 of the support region 253. For example, the channel 223 is disposed between about 0.1 inches to about 2 inches radially outward from the sidewalls 217 of the support region 253. In some embodiments the channel 223 includes a dovetail geometry. The dovetail geometry enables a seal, such as an O-ring, to be disposed therein. The channel 223 is described in more detail below.
The support region 253 is disposed radially inward of the mounting region 207. The support region 253 includes a support region thickness 248, a support region width 227, sidewalls 217, and a process face 215.
The support region thickness 248 is defined by the distance between the process face 215 and a recess face 210, of the recesses 209. The support region thickness 248 is between about 0.7 inches to about 0.2 inches, for example about 0.27 inches to about 0.39 inches. In some embodiments the support region thickness 248 is uniform. In other embodiments, the support region thickness 248 varies radially from the center to the process face 215 to the sidewalls 217.
The process face 215 partially defines the support region 253. The process face 215 includes a flat surface parallel to the mounting face 205. When the target 106 is placed in a process chamber, the process face 215 faces the substrate. The process face 215 includes a diameter. In some embodiments, the process face diameter is the same as the support region diameter 227. The process face 215 of the support region 253 has an angled face 203 at a downward slope, toward the upper face 221, from a first process face point 229 of the process face 215 to the second process face point 219. The support region diameter 227 is defined as the diameter formed by the sidewalls 217. The support region diameter 227 is about 15 inches to about 18 inches, for example about 17.5 inches. The sidewalls 217 are a radial vertical face that partially defines the support region 253. The sidewalls 217 have a height from the second process face point 219 to the upper face 221 of the mounting region 207. The sidewalls 217 height is between about 0.3 inches and about 0.4 inches. For example, the sidewalls 217 height is between about 0.32 inches and about 0.38 inches
The recess 209 is disposed opposite the process face 215 of the support region 253 and opposite the upper face 221 of the mounting region 207. The recess 209 is a cavity within the target 106. The recess 209 includes the recess face 210, a recess diameter 211, a recess radius 213, and a recess depth 249.
The recess depth 249 is between the recess face 210 and the mounting face 205. The recess depth 249 is between about 0.1 inches and about 0.15 inches. The recess 209 is recessed from the mounting face 205 to the recess face 210 by the recess depth 249. In some embodiments, the recess depth 249 is between about 0.1 inches and about 0.15 inches, for example, about 0.1 inches. The recess diameter 211 is between about 17 inches and about 20 inches. For example the recess diameter 211 is about 18.5 inches to about 19 inches. In some embodiments, the recess diameter 211 is between about 17.5 inches and about 19 inches, for example about 18.5 inches. In some embodiments, the recess diameter 211 is about 89% to about 90.5% of the total diameter of the target 106.
The target 106 also includes a height 256, a cross section 255, and an edge feature 300. The edge feature 300 is described in more detail in the discussion of
The cross section 255 is the thickness between the recess face 210 and upper face 221. The cross section 255 is about 0.3 inches to about 0.45 inches, for example, about 0.31 inches to about 0.35 inches. The cross section 255 is the cross sectional area of the target 106 that accounts for deflection during operation. If the cross section is too large, extra energy must be applied by the system to achieve a specific plasma density in the process volume. If the cross section 255 is too small, the target 106 experiences too much deflection that can lead to non-uniform erosion patterns and a reduction in the useful life of the target 106. In some embodiments, the cross section 255 is about 33% to about 37% of the target height 256. For example, the cross section 255 is about 35% of the target height 256.
As illustrated in
The coating 307 is disposed on the recess face 210 and extends at least a width W1 on to the mounting face 205. The coating 307 extends radially outward of the recess 209 by the width W1. The width W1 is configured to enable the coating 307 to form a sealing surface that is disposed between the mounting face 205 and an O-ring (not shown) when the target 106 is mounted in the chamber 101 (
When mounted, the target 106 does not need a backing plate since it is a single monolithic body able to be mounted to the magnetron assembly 111. In contrast, a target assembly with a target material disposed on a backing plate so the assembly can be mounted to the magnetron assembly. The backing plate produces eddy currents that affect the voltage through the target. The mitigation of a backing plate reduces the effect of eddy currents on the voltage flowing through the target 106 during operation.
The mounting region includes the channel 223. The center of the channel 223 is disposed about 0.82 inches to about 0.84 inches from the sidewalls 217. For example, the center of the channel 223 is disposed about 0.83 inches from the sidewalls 217. The channel 223 includes a depth 301. The depth 301 is the distance that the channel 223 is recessed into the upper face 221. The depth 301 is about 0.13 inches to about 0.15 inches from the upper face 221.
As shown, in
As shown, the channel 223 is disposed radially outward of the support region 253 and recess 209. This location further aids the target 106 by allowing additional strength to be imparted to the target rigidity through the cross section 255. If the recess 209 and channel 223 were overlapped, the cross section 255 would be further reduced, limiting the strength and rigidity of the target 106, which would diminish the target life 106.
The inventors have found the surprising effect of enhanced device life when a ratio between the recess depth 249 and the support region thickness 248 is between about 0.13 to about 0.15, for example about 0.14. In other words, the recess depth 249 is about 14% of the support region thickness 248.
The inventors have found the surprising effect of enhanced device life when a ratio between the height 256, the cross section 255, the recess depth 249, and the support region thickness 248 is about 0.9:0.12:0.33. For example, the target life is prolonged when the recess depth 249 is about 33% to about 37% of the cross section 255. For example, when the recess depth 249 is equal to about 35.5% of the cross section 255 distance.
Additionally, unlike multi-material targets, the monolithic target 106 bows away from the mounting face 205 and towards the process face 215. This change in the direction of the bow influences the importance of the above and below described dimensions. Thus, the corresponding ratios enhance the target life of the monolithic target 106.
When the word “approximately” or “about” are used, this term may mean that there may be a variance in value of up to ±10%, of up to 5%, of up to 2%, of up to 1%, of up to 0.5%, of up to 0.1%, or up to 0.01%.
While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
This application claims priority to U.S. Provisional Patent Application Ser. No. 63/536,230 filed on Sep. 1, 2023, which is herein incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63536230 | Sep 2023 | US |
