## 1 Introduction  
Focused ion beam-induced deposition (FIBID) and focused electron beam induced deposition (FEBID) enable a wide range of applications at the nanometer scale and show great advantages compared to conventional methods. Due to the high geometrical flexibility, high resolution, and independence from the surface, focused direct irradiation using electron or ion beams allows the fabrication of an almost endless variety of geometrical structures for a wide range of applications. The following are the main applications:  
* fabrication of three-dimensional structures in the micro--and nanometer scale [1, 2, 3, 4]
* growth of nanowires and nanocontacts [5, 6, 7, 8]
* interconnection or repair of circuits [9, 10, 11]
* repair of X-ray masks [12]More specialized applications are the maskless fabrication of JFETs (junction field effect transistor) [13], the preparation of nanogaps by FEBID [14], or the fabrication of nano-tips facing each other for tunneling applications [15]. Due to the maximum flexibility for post-processing of any nano/microelectromechanical system (NEMS/MEMS) and high patterning resolution, sharp tips with radii in the range of a few nanometers (nm) can be created. To use these tips for quantum tunneling applications, the tips are placed and patterned by a Thermo Fisher Helios NanoLab 600 DualBeam with a GIS and a Trimethyl(methylcyclopentadienyl)platinum(IV) (MeCpPtMe3) metal-organic precursor. Focused beam induced deposition can be divided into three main process steps: First, the precursor gas is introduced and floods the sample's environment. Second, the focused electron/ion beam is activated and scans the sample pixel by pixel in a specific geometric shape and sequence routine. Third, the precursor molecules are split into a non-volatile part, as well as a volatile part. The non-volatile part is deposited on the sample while the volatile part leaves the sample area. Theoretically, only the non-volatile metallic (Pt) part is deposited on the substrate. In fact, a metal-organic material is created, where individual platinum grains are embedded in a high-resistance amorphous carbon (C) matrix. This leads to high contamination of the Pt structure and much higher resistivity compared to bulk Pt. It is known that the conduction mechanism takes place by intrinsic tunneling between the platinum grains [16; 17; 18; 19; 20]. Since the tunneling mechanism in these granular metal-organic materials is responsible for the electrical conductivity, the question arises if tunneling through a vacuum gap with the same material is also possible. This opens up a large field of possibilities for the fabrication of novel and miniaturized MEMS and NEMS since the tunneling effect represents a highly sensitive measurement principle. For the use of PtC tips deposited and patterned by the FIB/FEB for quantum tunneling applications with a vacuum gap, the basic suitability and the dependence on the FIB/FEB parameters must be investigated. For this purpose, a series of tips is deposited on a lift-out grid and then investigated using HRTEM to find suitable parameters of FIBID/FEBID to enable quantum tunneling between PtC tips. The evidence for the tunneling effect and the comparison between different PtC tips is provided by integrating the tips subsequently in a MEMS.