Targets for Copper Metallization Processes

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Figure 1. The copper metallization scheme

Copper metallization in IC devices is gaining acceptance and appears to be the material of choice for high speed interconnects. Separation of copper from silicon through use of TaN barriers has enabled the successful introduction of this technology. The current method of choice is to reactively deposit TaN and a copper seed layer via PVD, followed by electro- deposition of blanket copper. Dual damascene structures are created following the removal of the blanket copper using chemical mechanical polishing (CMP). As shown in Figure 1 the new scheme produces a planarized film ideal for multilevel devices.

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Figure 2. Large grain starting material (left) is transformed to a fine grain CCH structure (right)

The new metallization requires well characterized tantalum and copper sputtering targets. Praxair MRC applies its CCH manufacturing concepts to produced controlled grain structures in both products.

Tantalum and copper sputtering targets

To assure reliable supply, Praxair MRC has qualified multiple vendors of starting raw material. Overall purity of 3N5 and 4N5 tantalum and 5N and 6N copper meet today’s advanced wafer fab requirements. Praxair MRC’s engineers focus on the impact of target microstructure on thin film properties. For Ta a fine grain microstructure (20-30µm) and a weak texture have been identified as essential for optimal film properties and higher yields.

Similar CCH processing technology yields Cu targets with an average grain size between 25 to 30 m m and a random crystallographic texture

Figure 3. Typical copper grain structure
Established high strength IntegraBond and MightyBond solid state bonding processes and solder PermaBonding™ techniques are used to produce reliable sputtering target assemblies. The MightyBond™ process is designed to maintain the fine grain structure achieved during the CCH process, while producing a high strength bond.

Praxair MRC’s CCH tantalum and copper targets are ideally suited for processes required in tomorrow’s copper metallized semiconductor devices using PVD systems such as Applied Materials Endura™ Novellus Inova™, M2I™;/MB2™/M200O™, TELs ECLIPSE® , Trikon Sigma™, CVC Connexion™, Ulvac Cereaus™ and Anelva systems employing advanced cathodes.

Endura is a trademark of Applied Materials Inc.
Inova, M2i, MB', M2000, Quantum, and Mini-Quantum are trademarks of Novellus Systems, Inc.
clipse is a trademark of Tokyo Electron, Ltd.
Sigma is a trademark of Trikon Technology, Inc.
Cereaus is a trademark of Ulvac, Ltd.
Connexion is a trademark of CVC, Inc.


CCH Process
CCH Do Aluminum Alloys
CCH Do and Do* Ti
Co and Ni
Ta and Cu

Thin Films Application Lab
Bonding Technology
Novellus Inova™ Tool
Endura™ & Centura™ Systems
RE-Al PLUS": Sputter Targets
Technical Papers  
  1. Reduction of TiN Nodule Density Through Optimization of Cathode and Process Variables
  2. Effect of Oxygen Content on Particle Generation in TiN Reactive Sputtering
  3. Link From Titanium Target Orientation to Titanium/Titanium Nitride/Aluminum Thin Film Orientations
  4. Technical Papers Available in PDF