Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/34—Sputtering
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/34—Sputtering
  • C23C14/3407—Cathode assembly for sputtering apparatus, e.g. Target
  • C23C14/3414—Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C9/00—Alloys based on copper
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/08—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of copper or alloys based thereon

Definitions

• the invention pertains to physical vapor deposition targets and methods of forming copper physical vapor deposition targets.
• PVD Physical vapor deposition
• Fig. 1 A diagrammatic view of a portion of an exemplary PVD apparatus 10 is shown in Fig. 1.
• Apparatus 10 includes a target assembly 12.
• the target assembly illustrated includes a backing plate 14 interfacing a PVD or "sputtering" target 16.
• Alternative assembly configurations (not shown) have an integral backing plate and target.
• targets can be referred to as 'monolithic' targets, where the term monolithic indicates being machined or fabricated from a single piece of material and without combination with an independently formed backing plate.
• apparatus 10 will include a substrate holder 18 for supporting a substrate during a deposition event.
• a substrate 20, such as a semiconductive material wafer, is provided to be spaced from target 16.
• a surface 17 of target 16 can be referred to as a sputtering surface.
• sputtered material 24 is displaced from surface 17 of the target and deposits onto surfaces within the sputtering chamber including the substrate, resulting in formation of a thin film 22.
• Sputtering utilizing system 10 is most commonly achieved with a vacuum chamber by, for example, DC magnetron sputtering or radio frequency (RF) sputtering.
• RF radio frequency
• Various materials including metals and alloys can be deposited using physical vapor deposition. Copper materials including high-purity copper and copper alloys are utilized extensively for forming a variety of thin film and structures during semiconductor fabrications. Sputtering targets are typically made of high-purity materials since the purity of materials can affect the deposited film with even minute particle-inclusions such as oxides or other non-metallic impurities can lead to defective or imperfect devices.
• the term 'high-purity' refers to the metallic purity in terms of the amount or percent by weight of a metal material (excluding gases) which consists of a particular metal or alloy.
• a 99.9999% pure copper material refers to a metal material where 99.9999% of the total non-gas content by weight is copper atoms.
• the invention encompasses physical vapor deposition targets.
• the targets are formed of copper material and have an average grain size of less than 50 microns.
• the targets additionally have an absence of course-grain areas throughout the target.
• the invention encompasses a physical vapor deposition target of a copper material and having an average grain size of less than 50 microns with a grain size non-uniformity (standard deviation) of less than 5% (1- ⁇ ) throughout the target.
• the copper material is selected from the group consisting of high-purity copper material containing greater than or equal to 99.999% copper, by weight, and copper alloys.
• the invention encompasses methods of forming copper physical vapor deposition targets.
• the methods include providing an as-cast copper material and performing a multistage processing of the as-cast material. Each stage of the multistage processing includes a heating event, a hot-forging event, and a water quenching event. After the multistage processing the copper material is rolled to produce a target blank.
• Fig. 1 is a diagrammatic view of a portion of an exemplary physical vapor deposition apparatus.
• FIG. 2 is a flowchart diagram outlining methodology in accordance with one aspect of the invention.
• FIG. 3 shows a comparison of grain structures of target blanks produced utilizing conventional methodology (Panel A) and methodology in accordance with the invention (Panel B).
• the invention involves production of physical vapor deposition targets having improved grain size uniformity such that areas of course grains are significantly reduced or eliminated relative to targets produced utilizing conventional methodology.
• the invention was developed for production of high-purity copper targets and high-purity copper alloy targets where the term "high-purity” typically refers to a base metallic purity of greater than or equal to 99.99%. Where the material is an alloy, the term “high purity” refers to the purity of the base copper to which one or more alloying elements have been added.
• methodology of the invention can be adapted for production of targets of alternative metal or alloy materials.
• Targets in accordance with the invention can be produced to have a target size and shape configuration appropriate for utilization in conventional or yet to be developed PVD deposition systems.
• Targets of the invention can be constructed for utilization with a backing plate in configurations such as that illustrated in Fig. 1.
• targets of the invention can be monolithic targets which can be utilized in an absence of an independently formed backing plate.
• Copper targets in accordance with the invention can comprise high-purity copper or high-purity copper alloy, can consist essentially of high-purity copper or high- purity copper alloy, or can consist of high-purity copper or high-purity copper alloy.
• the copper material comprises a copper alloy
• a material can preferably comprise copper and at least one element selected from the group consisting of Ag, Al, In, Mg, Sn, and Ti.
• Preferred copper alloys can contain less than or equal to about 10% of total alloying elements, by weight.
• thermomechanical processing in accordance with the invention can utilize multi-stage processing where each stage includes a heating event, followed by a forging event and subsequent quenching.
• the multi-stage processing will include at least two stages or “rounds" of heating, forging and quenching and can comprise three or greater than three stages.
• the temperature during the heating event is not limited to a particular value and can vary depending upon the specific material being processed.
• an initial stage of the multi-stage processing can utilize a heating event that is conducted at a first temperature while a second stage heating event is conducted at a second temperature which varies relative to the first temperature.
• each heating event in the multi-stage processing is conducted at a temperature of greater than about 900 0 F.
• high-purity copper and particular copper alloys will be heated at 1050 0 F for at least 30 minutes during each heating event, and in some instances may be heated for at least 60 minutes. It is to be understood that the heating time will vary depending upon the particular heating temperature.
• forging events can utilize hot upset forging.
• a forging event conducted in a first stage of multi-stage processing will produce a forged block having a first height (block thickness) and a subsequent forging event conducted in a subsequent stage of the multi-stage processing will produce a forged block having a second reduced height.
• the forged block is preferably quenched into cold water. Such quenching is preferably conducted for at least 8 minutes with specific time being determined by the material mass and block thickness.
• Multi-stage processing ultimately results in a final forged block which is subsequently subjected to a rolling process 1 16.
• Rolling process 1 16 preferably comprises cold rolling for further thickness reduction of the forged block.
• Rolling process 1 16 produces a rolled blank which is typically machined and cleaned to form a target blank.
• the rolled blank can be subjected to additional processing comprising a heat treatment 118.
• the heat treatment can be performed as part of the target/backing plate bonding process.
• bonding is conducted utilizing hot isostatic pressing (HIPping).
• HIPping will typically be conducted at a temperature of at least about 480°. It is to be understood however, that the particular bonding temperature during HIPping can vary depending upon the particular high-purity copper material or copper alloy material being bonded. In specific instances where a high-purity copper material or particular copper alloys are utilized, the bonding will be performed utilizing a temperature of approximately 662°F for about 2 hours. In accordance with the invention, such bonding produces a diffusion bond having a bond strength of greater than about 20 ksi.
• the target/backing plate assembly can be further processed by machining to form a finished copper or copper alloy target assembly.
• the heat treatment performed as part of the bonding process results in annealing or recrystallization of the copper material.
• the combination of the multi-stage processing and recrystallization results in fine grain size and uniform grain distribution with essentially no course grain areas, and in particular instances results in an absence of course grain areas throughout an entirety of the target.
• the rolled blank can be subjected to heat treatment 1 18 by annealing/recrystallizing at a heat treatment temperature as discussed above with respect to heat treatment process 1 18.
• the heat treatment will comprise annealing/recrystallizing at a temperature of at least about 48O 0 F, and in particular instances about 662° F for about 2 hours.
• the target blank is machined to produce a monolithic copper or copper alloy target for use without a backing plate.
• the heat treatment results in recrystallization. Due to the previous multistage processing, the recrystallization results in essentially no course grains and typically an entire elimination of course grains throughout the monolithic target.
• targets produced utilizing methodology as presented in Fig. 2 consistently have average grain sizes of less than 50 microns with a standard deviation of less than 10% (1- ⁇ ). In particular instances the standard deviation is less than 5% (1- ⁇ ).
• FIG. 3 a comparison of target blanks produced by conventional methodology (Panel A) and methodology in accordance with the invention (Panel B) is shown.
• the conventional target blank shown in Panel A has visible rough/shiny regions corresponding to course grain areas having grains of sizes exceeding 100-200 microns.
• the target blank shown in Panel B produced in accordance with methodology of the invention has a notable absence of any such rough/shiny regions and in fact has an absence of course grain regions.
• a 6 inch diameter by 10 inch high as-cast copper alloy billet was heated at 1050 0 F for 60 minutes. The billet was then subjected to hot forging to a first block height of 6.0 inches. The block was quenched into cold water for longer than 8 minutes. The quenched block was reheated at 1050 0 F for 30 minutes followed by hot forging to a resulting second height of 3.3 inches. The twice forged block was quenched into water for greater than 8 minutes. The resulting forged block was then cold rolled to an ultimate thickness of 0.93 inches. The rolled blank was machined and cleaned and was subsequently bonded to a CuCr backing plate by hot isostatic pressing at 662°F for 2 hours. The resulting target/backing plate assembly was machined to a finished copper alloy target assembly. The final target had a uniform grain size distribution with a standard deviation of less than 5% (1- ⁇ ) and an average grain size of less than 50 microns.
• a rolled copper alloy blank was prepared as described above in Example
• the rolled alloy blank was annealed by heat treating at 662°F for 2 hours.
• the resulting target blank was machined to produce a monolithic copper alloy target which had a resulting grain size average less than 50 microns and a uniform grain size distribution having a standard deviation of less than 5% (1- ⁇ ) throughout the target.
• a high-purity (99.9999% by weight) copper as-cast billet was subjected to two rounds of heating, hot forging, and water quenching, followed by cold rolling as described in Example 1.
• the rolled copper blank was machined and cleaned and was bonded to a CuCr backing plate at 662°F for 2 hours utilizing hot isostatic pressing. After bonding, the assembly was machined to form a finished copper target assembly.
• the resulting bond strength was greater than 20 ksi.
• the target had an average grain size of less than 50 microns and a grain size distribution standard deviation of less than 5% (1- ⁇ ).
• the blank was subjected to annealing by heating at 662°F for 2 hours.
• the target blank was subsequently machined to produce a monolithic target.
• the monolithic target had an average grain size of less than 50 microns and a grain size distribution uniformity of less than 5% (1- ⁇ ).
• Table 2 Grain size (microns) uniformity for multi-stage processed targets.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
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• Mechanical Engineering (AREA)
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• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Physical Vapour Deposition (AREA)
• Electrodes Of Semiconductors (AREA)

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• 2006
  • 2006-05-01 US US11/415,621 patent/US20070251818A1/en not_active Abandoned
• 2007
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• 2008
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