Atomic Layer Deposition (ALD)

Since 2006, Fraunhofer ENAS and the Center for Microtechnologies of Chemnitz University of Technology perform collaborative research and development work on atomic layer deposition processes for different applications. The activities comprise the precursor evaluation, the development of ALD processes and the optimization of established processes, e.g. for system integration. These steps can be supported by the simulation of precursor properties, reaction paths, and flow conditions within the reaction chamber.

Three systems are available for ALD processes:

• a FlexAl chamber (Oxford Instruments) for standardized processes with conventional bubbler evaporators for precursors with high vapor pressure,
• two chambers at Roth&Rau microcluster for process and precursor evaluation,
• and a scia Atol 200 system (scia Systems) with bubblers, and direct evaporations systems for precursors with variable vapor pressures.

At the scia Atol 200 system from scia Systems evaluation, development and optimization of ALD processes can be facilitated with the help of the integrated ellipsometer (iSE from Woollam) as well as a measurement chamber for contactless resistance determination (EddyCus von Suragus). Within the Roth&Rau microcluster an X-ray photoelectron spectrometer (XPS) is integrated, which is used for determination of the layer composition without vacuum interruption. XPS measurements are also possible for externally prepared wafers and samples.

The equipment is appropriate for 200 mm wafers as well as smaller substrates.

With the available ALD processes, (high-k) materials, such as aluminum oxide, hafnium oxide and titanium oxide as well as metallic layers such as cobalt can be deposited.

Competency:

• Deposition of oxidic (high-k) materials, such as HfO₂, TiO₂ and Al₂O₃
• Deposition of metallic layers, e.g. Co
• Variable layer thicknesses
• Evaluation, development, and application of ALD processes
• Precursor evaluation / Precursor screening
• Wafer sizes up to 200 mm diameter
• Simulation of ALD processes, reactors and gas flow
• X-ray photoelectron spectroscopy (XPS) for determination of layer composition, analysis of oxidation- and bonding states