<p>
As a possible alternative for growing seed layers
required for electrochemical Cu deposition of
metallization systems in ULSI circuits,
the atomic layer deposition (ALD) of Cu is
under consideration. To avoid drawbacks related
to plasma-enhanced ALD (PEALD), thermal growth
of Cu has been proposed by two-step processes
forming copper oxide films by ALD which are
subsequently reduced.
</p>
<p>
This talk, given at the 8th International
Conference on Atomic Layer Deposition
(ALD 2008), held in Bruges, Belgium from
29 June to 2 July 2008, summarizes the results
of thermal ALD experiments from
[(<sup><i>n</i></sup>Bu<sub>3</sub>P)<sub>2</sub>Cu(acac)]
precursor and wet O<sub>2</sub>. The precursor is of particular
interest as it is a liquid at room temperature
and thus easier to handle than frequently
utilized solids such as Cu(acac)<sub>2</sub>,
Cu(hfac)<sub>2</sub> or
Cu(thd)<sub>2</sub>. Furthermore the substance is
non-fluorinated, which helps avoiding a major
source of adhesion issues repeatedly observed
in Cu CVD.
</p>
<p>
As result of the ALD experiments, we obtained composites of metallic and
oxidized Cu on Ta
and TaN, which was determined by
angle-resolved XPS analyses. While smooth,
adherent films were grown on TaN in an ALD
window up to about 130°C, cluster-formation due to
self-decomposition of the precursor was observed
on Ta. We also recognized a considerable
dependency of the growth on the degree of
nitridation of the TaN. In contrast, smooth
films could be grown up to 130°C on SiO<sub>2</sub>
and Ru, although in the latter case the ALD window
only extends to about 120°C. To apply the ALD
films as seed layers in subsequent electroplating
processes, several reduction processes are
under investigation. Thermal and plasma-assisted
hydrogen treatments are studied, as well as
thermal treatments in vapors of isopropanol,
formic acid, and aldehydes. So far these
attempts were most promising using formic
acid at temperatures between 100 and 120°C,
also offering the benefit of avoiding
agglomeration of the very thin ALD films on
Ta and TaN. In this respect, the process
sequence shows potential for depositing
ultra-thin, smooth Cu films at temperatures
below 150°C.
</p>
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa.de:bsz:ch1-200800914 |
| Date | 15 July 2008 |
| Creators | Waechtler, Thomas, Oswald, Steffen, Roth, Nina, Lang, Heinrich, Schulz, Stefan E., Gessner, Thomas |
| Contributors | TU Chemnitz, Institut für Chemie, TU Chemnitz, Fakultät für Elektrotechnik und Informationstechnik, Leibniz-Institut für Festkörper- und Werkstoffforschung (IFW), Dresden,, Fraunhofer-Einrichtung für Elektronische Nanosysteme (ENAS), Chemnitz,, American Vacuum Society (AVS), |
| Publisher | Universitätsbibliothek Chemnitz |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | doc-type:lecture |
| Format | application/pdf, text/plain, application/zip |
| Source | 8th International Conference on Atomic Layer Deposition (ALD 2008), Bruges, Belgium, 29 June to 2 July 2008 |
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