Description
Lithography for contacting individual nanowires / nanosheet materials
We offer processing workflows for contacting nanowire/nanosheet materials. Briefly, the process involves dispersing nano-materials of choice (normally obtained by growth and supplied by the user) on carrier wafer with gown insulating oxide and with pre-defined markers and large contact pads. This is followed by precise (<30nm) pattern-to-pattern alignment, EBL exposure and metal lift-off to define contacts. For nonplanar materials e.g. vertical pillars or other complex structures we offer direct write lithography method using EBID process. While the EBID offers extreme flexibility in design and even the possibility to contact individual facets of grown structures it is limited by the inferior purity of developed metal contacts, and larger resistance of the metal lines developed.
Keywords
Grown nanowires, nanosheets, contacting, EBL, EBID
Ascent+ facility
Tyndall
Platform Technology
- Disruptive Devices
Key Enabling Capability
- Processing: Nanoscale lithography
Case Study
Contacting ZnO Individual Crystal Facets by Direct Write Lithography
Many advanced electronic devices take advantage of properties developed at the surface facets of grown crystals with submicrometer dimensions. Electrical contacts to individual crystal facets can make possible the investigations of facet dependent properties such as piezoelectricity in ZnO or III-nitride crystals having noncentrosymmetric structure. However, a lithography-based method for developing contacts to individual crystal facets with submicrometer size has not yet been demonstrated. We used electron beam-induced deposition (EBID), a direct write lithography method, for contacting individual facets of ZnO pillars within an electron microscope. Correlating structural and in situ deposition and electrical data, we examine proximity effects during the EBID and evaluate the process against obtaining electrically insulated contact lines on neighboring and diametrically opposite ZnO facets. Parameters such as incident beam energy geometry and size of the facets were investigated with the view of minimising unwanted proximity broadening effects. Additionally, we showed that the EBID direct write method has the required flexibility, resolution, and minimised proximity deposition for creating prototype devices. The devices were used to observe facet-dependent effects induced by mechanical stress on single ZnO pillar structures.
