Direct-Writing Technology of Nanostructures

The phenomenon of deposition, known since the 50s of the last century was discovered first with the invention of the electron microscope. Back then deposition was considered an undesirable side-effect of imaging (“contamination”). Nowadays with the rapid development of computer chip technology deposition can be used specifically for commercial production and processing of surfaces on the nanoscale. With the help of this technique, which presents a direct process, in contrast to the multilayered conventional semi-conductor technology, it is possible to produce nanostructures down to the 20 nm range in a single processing stage. Costly and error prone preparations which are usually necessary before the structuring process can thus advantageously be omitted. This technique is also renowned for its unsurpassed flexibility and capability for truly three-dimensional pattern formation. The microstructure of the created patterns is of a nano-composite type with mechanical and electrical properties which are widely tunable by controlled changes of the preparation conditions.

The structuring process is schematically illustrated in the following image:

Fig.1: Enhancement: Within a hermetically closed environment as for example the sample chamber of an electron microscope the basic substance (precursor) out of which the desired micro structure is to be manufactured is first put up on the substratum. There it is at the disposal in gaseous form as adsorbent and building structure for the following structural composition.

Fig. 2: Deposition: First the adsorbent gas loosely bound to the substrate is processed with a focused beam of electrons or ions irradiating the adsorbent gas pointedly. Molecule dissociation occurs in the focus of the beam. At the point of shine in which typically has a diameter of only a few nanometers a deposition develops which is composed of the then hardened (solid) phase of the adsorbent. With increasing irradiation the column (deposit) illustrated in 2) grows. Its diameter corresponds to the size of the area of irradiation (5 to several hundred nanometers). Aspect relations (width-height relationships) of 1:100 and more can be achieved without effort applying the according length of irradiation.

Fig. 3: 3D structuring: A controlled collateral movement of the beam and/or stage leads to the solid phase (which now also illustrates the desired microstructure) following the movement of the beam and/or stage. The straight column in 2) develops into the illustrated micro arc, which can be fed into further truly three-dimensional patterns. As a consequence, the mechanical and electrical properties of the deposits are widely tunable for optimizing the desired functionality.

Nano Scale Systems GmbH focuses its special expertise in direct surface processing on the development of silicone free nano composite materials. These nano composites open up new fields of application in integrated electronics, optics and optoelectronics as well as various areas of sensing.

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