K2 Large scale laser deposition of memristive oxides

Heterostructures of complex oxides such as Pr_0.7 Ca_0.3MnO₃ (PCMO) are highly interesting memristive devices for the emulation of synaptic properties in neuromorphic circuits, which the Peter Grünberg Institute for Electronic Materilaien (PGI-7) is investigating within the NEUROTEC project in work package WP1.2. Due to the ease of transfer of stoichiometry in pulsed laser deposition (PLD), this method is particularly suitable for the deposition of complex oxides. However, it usually only allows deposition on 10x10mm² substrates. In order to coat future chip generations with complex memristive oxides, it is necessary to carry out the coating of small substrates, which has been extensively investigated on a laboratory scale, with the same quality on large Si wafers. In the K2 cooperation project, the SURFACE company together with the PGI-7 is researching novel concepts for coating wafers up to 100 mm in diameter using PLD. Within the framework of this cooperation, the basis for the development of industrial system modules for large-area PLD is to be created.

SURFACE (link) has been building PLD coating systems for research facilities for almost 30 years. The two lines of equipment manufactured to date are used exclusively in materials research, where only the coating of 10x10mm² single crystals is required. Occasionally, SURFACE has built systems up to 5" substrate size. However, these were based on the same system concept used for smaller substrates. Within the scope of NEUROTEC, a novel concept for performing PLD processes is to be explored, which allows the upscaling of the process to 100mm and larger. Besides the homogeneity of the layers, the reduction of the intrinsic particles (droplets) for the PLD process is in the foreground.

K2's goals in NEUROTEC are as follows:

1. Reduction of the droplet emission and reduction of the impact on the substrate with simultaneous increase of the substrate area in the PLD.
2. Validation of the improvement in the quality of the deposition of PCMO layer sequences and influence of the improvement on the function of the layer sequences as memristive device.
3. Concept for the transfer of the researched findings into the development of industrial plant modules.