Patent Application
20070295596
So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, 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 typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
For clarity, identical reference numerals have been used, where applicable, to designate identical elements that are common between figures.
Target assembly 310 includes a magnet assembly 350, which is housed in a magnetron chamber 309, and a target 311, which is bonded to a backing plate 312 by a bonding layer 313. Magnet assembly 350 may be an array of a plurality of magnets that rotates or linearly translates parallel to target 311 in order improve deposition rate and uniformity of a PVD-deposited film on substrate 331. Magnetron chamber 309 may be at atmospheric pressure, evacuated to a pressure below atmospheric pressure, or filled with an electrically insulative cooling fluid, such as deionized water. Power is provided to target 311 via an electrical connection. In one aspect, an electrical connection 314A may be electrically coupled to backing plate 312 to energize target 311. In another aspect, an electrical connection 314B may be electrically coupled to target 311 directly. Power may be DC, AC, or pulsed power. Target 311 consists of the material, typically in a highly purified state, that is to be deposited on substrate 331 in PVD chamber 300. Bonding layer 313 may be an elastomeric bond or a metallic adhesive bond, such as an indium-containing bonding layer. In the latter case, a surface of a target and a surface of a backing plate are deposited with an indium-based coating, also referred to as indium solder, and pressed together at an elevated temperature. Upon cooling, the indium-containing layer solidifies and bonds the target 311 to the backing plate 312.
In one configuration, wherein power is provided to target 311 by electrical connection 314A and bonding layer 313 is an elastomeric bonding material, bonding layer 313 may contain an additional conductive member (not shown for clarity), such as a copper mesh, to provide improved electric contact between the backing plate and the target. In a preferred embodiment, however, target 311 is energized directly via electrical connection 314B in order to obviate the need for energizing target 311 indirectly via backing plate 312 and bonding layer 313.
Substrate support 330 is disposed inside PVD chamber 300 and positions a substrate 331 adjacent the processing region 360 of PVD chamber 300 during PVD processing. Shield 340, also referred to as a dark space shield, may be mounted inside PVD chamber 300 and proximate target sidewall 315 to protect the inner surfaces of body 320 and target sidewall 315 from unwanted deposition during PVD processing and/or to provide an electrically grounded anode region. Processing region 360 is the region in PVD chamber 300 that includes the volume bounded by substrate support 330, target 311, and shield 340.
Target assembly 310 is sealably mounted on upper surface 323 of body 320 in a vacuum-tight manner. By mounting target assembly 310 via a sealable mount on upper surface 323, target assembly 310 may be removed for repair or replacement with minimal disassembly of PVD chamber 300. The vacuum-tight seal is typically formed by means of a sealing member 321, such as an O-ring, positioned in or against sealing surface 322, such as an O-ring groove.
Alternatively, aspects of the invention contemplate configurations of sealably mounting target assembly 310 on upper surface 323 wherein sealing member 321 is not an O-ring and sealing surface 322 is not an O-ring groove. For example, target 311 may be sealably mounted to upper surface 323 using an all-metal vacuum seal, wherein sealing member 321 may be a metal gasket, such as a copper strip, compressed against sealing surface 322, which is a stainless steel knife-edge seat. In another example, sealing member 321 may be a polymeric seal, such as a gasket-like G-10 material.
In one configuration, target 311 is fabricated from a single piece of material. In this way the only surface of target 311 in fluid contact with processing region 360 is a single machined surface, i.e., there is no transition between two or more materials to create sharp, arc-inducing features.
Aspects of the invention further contemplate the use of a direct electrical connection 314B (see
In one aspect of the invention, backing plate 312 contains a plurality of cooling conduits 308 through which a cooling fluid may be flowed to prevent overheating of target 311 and backing plate 312 during processing.
Aspects of the invention may likewise be used to advantage for a PVD chamber whose target assembly includes a multi-piece target.
In the configuration illustrated in
Referring to
The peripheral seal formed around each of targets 511A-C may be a vacuum-tight seal, for example the portions of the seal formed between upper surface 323 and target surface 326, preventing leakage from atmosphere into processing region 360. Other portions of said seals may not be vacuum-tight seals, for example when the volumes on each side of the seal are at vacuum. This may be the case when regions 581 are evacuated regions and the seals between regions 581 and processing region 360 are only required to prevent contamination from entering processing region 360. It is important to note that the peripheral seal formed by sealing members 521A-C against targets 511A-C, respectively, isolates bonding layer 313 from processing region 360. This configuration eliminates contamination of processing region 360 from bonding layer 313 as well as arcing due to sharp points and/or rugosities associated with bonding layer 313.
Center shield 540 protects surfaces from unwanted deposition, for example target center sidewalls 515A, 515B and target support members 513A, B. As described above for target 311 in conjunction with
For a multi-target configuration, the inventors have learned that a normal orientation of the target sidewall minimizes deposition thereon and reduces subsequent particle contamination of substrates. Therefore, in one aspect, one or more sidewalls of targets 511A, 511B, such as interior sidewalls 550A, 551B, respectively, are oriented substantially normal to the surface of substrate support 330.
The inventors have also learned that aspects of the invention may be used to advantage for PVD chambers adapted to process large-area substrates. Processing large-area substrates requires larger PVD target assemblies. Larger PVD target assemblies are more likely to benefit from the structural rigidity provided by a backing plate bonded to the target, and therefore may benefit from aspects of the invention. In addition, large-area substrates may require multi-piece target assemblies, which may also benefit from aspects of the invention.
Substrates of the invention can be of any shape (e.g., circular, square, rectangle, polygonal, etc.) and size. Also, the type of substrate is not limiting and can be any substrate comprised of a material of silicon, carbon-containing polymer, composite, metal, plastic, or glass.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
