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New precursors for CVD copper metallization

: Norman, J.A.T.; Perez, M.; Schulz, S.E.; Wächtler, T.


Schulz, S.E.:
MAM2008, Proceedings of the Twelth European Workshop on Materials for Advanced Metallization 2008 : A single-session workshop devoted to materials research, materials properties and interactions. March 2 - 5, 2008, Dresden, Germany
Amsterdam: Elsevier, 2008 (Microelectronic engineering 85.2008, Nr.10)
ISSN: 0167-9317
European Workshop on Materials for Advanced Metallization (MAM) <12, 2008, Dresden>
Konferenzbeitrag, Zeitschriftenaufsatz
Fraunhofer ENAS ()
Fraunhofer IZM ()

A novel CVD copper process is described using two new copper CVD precursors, KI3 and KI5, for the fabrication of IC or TSV (Through Silicon Via) copper interconnects. The highly conformal CVD copper can provide seed layers for subsequent copper electroplating or can be used to directly fabricate the interconnect in one step. These new precursors are thermally stable yet chemically reactive under CVD conditions, growing copper films of exceptionally high purity at high growth rates. Their thermal stability can allow for elevated evaporation temperatures to generate the high precursor vapor pressures needed for deep penetration into high aspect ratio TSV vias. Using formic acid vapor as a reducing gas with KI5, copper films of >99.99 atomic % purity were grown at 250 °C on titanium nitride at a growth rate of > 1500 Å/min. Using tantalum nitride coated TSV type wafers, not, vert, similar 1700 Å of highly conformal copper was grown at 225 °C into 32 ?m × 5 ?m trenches with good adhesion. With ruthenium barriers we were able to grow copper at 125 °C at a rate of 20 Å/min to give a continuous not, vert, similar 300 Å copper film. In this respect, rapid low temperature CVD copper growth offers an alternative to the long cycle times associated with copper ALD which can contribute to copper agglomeration occurring.