Recent Developments of Atomic Layer Deposition Processes for Metallization

Atomic layer deposition (ALD) has become an enabling technology for a wide range of applications where depositions of high quality, conformal thin films are desired. The needs of conducting materials with tailored properties call for ALD metallization processes that can meet diverse requirements in various applications. Recent developments of ALD processes for conducting materials have led to some novel ALD chemistries. Most of the ALD binary materials are formed in a typical AB sequence from two reactants. More complex ternary and doped materials can be achieved according to the same AB sequence principle through nano-lamination of two binary materials using three or more reactants. It is demonstrated that ternary and elemental materials can be deposited using two reactants with a basic ALD AB sequence. Furthermore, an ALD process is not limited to an AB sequence, an ABC sequence with a surface-controlled ALD reaction is also possible. A double replacement reaction mechanism is proposed with examples of novel processes such as TaCxNy, WCx, and WNxCy. Recent developments of ALD metallization processes have opened up more opportunities of producing novel ALD materials for industrial applications.