46 Prakt. Met. Sonderband 52 (2018) 
2. Fabrication of thin-film materials libraries 
Thin-film materials libraries can be fabricated by combinatorial magnetron sputter processes 
[e.g. 5]. Sputtering is a versatile process which is also frequently used in industry. Therefore, 
findings from the screening of materials libraries can be transferred to industrial (thin-film) 
applications. In order to achieve well-defined composition gradients, the materials in thin- 
film libraries are deposited in the form of (virtual) wedge-type films. The two most important 
methods for the fabrication of materials libraries are co-deposition and multilayer deposition 
of wedge-type layers. In co-deposition at least two sputter sources are used simultaneously, 
both aiming on a substrate. In one of our co-deposition systems up to five sources can run 
simultaneously. The co-deposition process results in an atomic mixture of the deposited film. 
This method is especially suitable for the fabrication of metastable materials if the deposition 
is carried out at room temperature. However, fabrication of complete systems, spanning a 
composition range from 0 to 100 at.% is not possible with co-deposition. For up to complete 
ternary systems, the multilayer deposition method is suitable: nanoscale wedge-type layers 
are deposited which are oriented to each other by 180° (binaries) or 120° (ternaries). Phase WG 
formation can be achieved by annealing at suitable temperatures after the deposition. If 
phase formation by annealing was successful, needs to be proven by characterization 
methods such as cross-section electron microscopy or X-ray photoelectron spectroscopy 
(XPS) depth profiling. The thickness of the thin-film libraries should be in the range of several 
hundreds of nanometers to enable reliable high-throughput characterization methods and to fable 
avoid nanoscale effects (if these are not the scope of the study). oom 
001 
3. High-throughput characterization methods 
In the following, the most important high-throughput characterization methods for multinary 
thin film materials libraries are discussed. Table 1 gives an overview of high-throughput 
characterization methods. The used high-throughput methods have to be fast and applicable 
to a multitude of measurement areas, but they also need to yield measurement results which Inst 
are, if possible, of the same quality as single measurements. Mech 
For a comprehensive understanding of the materials, as many properties as possible should - 
be measured. Basic measurements are to determine the chemical compositions comprised ’ 
in the materials library as well as the phases being present. The further applied high- Date 
throughput characterization methods correspond to the material development goals. lee 
Whereas in some cases completely continuous materials libraries are used, it is in most ri 
cases better to use a library which is structured into measurement areas, however, without a 
losing to much of the thin-film composition spread. In the following examples, the libraries ) 
comprise 342 measurement areas over a 100 mm diameter substrate (typically thermally © 
oxidized Si wafer), see Figure 1a). Figure 1b) shows a photograph of a thin-film materials 
library. The crosses, defining the measurement areas, are fabricated by a photolithographic 
lift-off process (pre-patterned substrate). The numbered crosses, where no thin film is 
applied, are used for thickness measurements and are useful for navigation on the wafer 
when performing high-throughput characterization.