Focused electron beam induced etching (FEBIE) with chlorine as etching agent has been used to geometrically shape and to electrically modify semiconductor nanodevices. Selected sections of monocrystalline nanowires were modified directly without the requirement for a photomask or a resist layer. FEBIE as a subtractive nanofabrication technology allows to locally etch active semiconductor devices made of Si or Ge. In this work, chlorine is used as the etchant gas to thin germanium channel structures fabricated by standard photolithography. For effective material removal a sufficiently high electron influence is essential to avoid the pitfalls of this method. Topography and conductivity of FEBIE-modified structures prior and after the etching process was studied by AFM and by electrical I–V characteristics. The presented work demonstrates the potential of Cl-based FEBIE for device prototyping and electrical trimming of future Ge-based nanodevices.

A series of star shaped organic semiconductors was synthesized and characterized. The applicability of these materials in organic electronic devices was demonstrated.

FIB technologies possess a unique ability to form topographies that are difficult or impossible to generate with binary etching through typical photo-lithography. The ability to arbitrarily vary the spatial dose distribution and therefore the amount of milling opens possibilities for the production of a wide range of functional structures with applications in biology, chemistry, and optics. However in practice, the realization of these goals is made difficult by the angular dependence of the sputtering yield and redeposition effects that vary as the topography evolves. An inverse modeling algorithm that optimizes dose profiles, defined as the superposition of time invariant pixel dose profiles (determined from the beam parameters and pixel dwell times), is presented. The response of the target to a set of pixel dwell times in modeled by numerical continuum simulations utilizing 1st and 2nd order sputtering and redeposition, the resulting surfaces are evaluated with respect to a target topography in an error minimization routine. Two algorithms for the parameterization of pixel dwell times are presented, a direct pixel dwell time method, and an abstracted method that uses a refineable piecewise linear cage function to generate pixel dwell times from a minimal number of parameters. The cage function method demonstrates great flexibility and efficiency as compared to the direct fitting method with performance enhancements exceeding ∼10× as compared to direct fitting for medium to large simulation sets. Furthermore, the refineable nature of the cage function enables solutions to adapt to the desired target function. The optimization algorithm, although working with stationary dose profiles, is demonstrated to be applicable also outside the quasi-static approximation. Experimental data confirms the viability of the solutions for 5×7μm deep lens like structures defined by 90 pixel dwell times.

Magnetic materials synthesized on the nanometer-scale level are essential for several applications, such as spintronics and magnetologic. As a successful nanofabrication approach, focused electron beam-induced deposition (FEBID) stands out as a direct-write technique. FEBID uses an electron beam to locally induce a CVD process, avoiding the use of masks and resists. In this work, Fe–based nanostructures are synthesized on Si(100) by FEBID, starting from iron pentacarbonyl. A systematic variation of FEBID parameters is performed, to study their influence on the geometry and composition of the deposit. Based on the results, specific deposition conditions are suggested for magneto-logic applications and fabrication of large structures.

Inorganic hardmasks are routinely employed in reactive ion etching (RIE) processes due to their excellent etch resistance. However, since pattern definition is commonly performed using organic resist materials, the enhanced etch resistance provided by the inorganic hardmasks comes at the expense of added process complexity. In this work, the authors introduce the method of direct patterning of hard masks (DPHM) utilizing milling and gas assisted deposition (GAD) with a focused ion beam (FIB). DPHM by FIB allows to structure hardmask materials, which are otherwise not accessible with standard processes. Further, it reduces the high number of (typically seven) processing steps required for resist based patterning down to only three using FIB milling of hardmasks or even two using FIB GAD for patterning. The authors found that by FIB milled hard masks made of oxide such as aluminum zinc oxide exhibited excellent pattern clarity. For other materials, effects such as ion beam induced dewetting were found to affect the patterning result and must be considered in the choice of hardmask materials. Comparing DPHM and RIE to pure FIB milling of bulk material a speed enhancement of at least 755 times has been achieved. DPHM by FIB milling offers the highest versatility in material choice while FIB GAD enables faster patterning of selected hardmask materials.

Ga implantation into Si and reactive ion etching has been previously identified as candidate techniques for the generation of 3D nanopatterns. However, the structures manufactured using these techniques exhibited impedingly high surface roughness. In this work, we investigate the source of roughness and introduce a new patterning process to solve this issue. The novel patterning process introduces an additional layer absorbing the implanted Ga, thus preventing the clustering of the implanted Ga observed with uncoated Si substrates. This process enables 3D nanopatterning with sub-100 nm lateral resolution in conjunction with smooth height transitions and surface roughness down to 4 nm root mean square. Such patterns are ideally suited for optical applications and enable the manufacturing of nanoimprint lithography templates for low-profile Fresnel lenses.

Ultravoilet (UV)-nanoimprint lithography (NIL) master stamps are subject to wear due to the mechanical nature of the imprint process. To extend the useful lifespan of expensive NIL master stamps, a focused ion beam repair process is highly desirable. Due to the inevitable Ga-staining induced by the focused ion beam processing the transmissivity of repaired NIL stamps is locally degraded. In this work, the authors investigate the impact of Ga-induced transmission losses on the imprint process. Experimental results indicate that the reduced transparency mainly impacts the amplitude of bow deformations in the imprint. These deformations are strongly enhanced by Ga-staining of the master stamp. The authors present a method for quantification of such bow-deformations. The introduced bowing-factor allows to make a qualified decision on whether the occurring deformation is acceptable for the target application. The authors have achieved control over the extent of the Ga-induced bow-deformation by tuning the UV-dose applied during NIL resist exposure. The bowing-factor provides excellent guidance for adapting the required exposure-dose of the NIL resist to reduce the bow-deformation to an acceptable level. With the presented approach, the mitigation of Ga-staining induced defects in the imprint is successfully achieved.

Nanoimprint lithography (NIL) has the unique capability to replicate 3D patterns in one single step. However, to exploit this feature high quality, 3D patterned NIL stamps are required. While grayscale electron-beam lithography suffers from resolution limitations due to proximity effects, focused ion beam (FIB) milling and gas assisted etching is inherently slow. We introduce a new 3D patterning process based on FIB implantation and subsequent reactive ion etching (RIE) for NIL stamp fabrication. The presented process is more than 100 times faster than FIB milling. We demonstrate NIL stamps with complex 3D patterns and resolutions down to 50nm fabricated with this process.

Recently focused-electron-beam-induced etching of silicon using molecular chlorine (Cl(2)-FEBIE) has been developed as a reliable and reproducible process capable of damage-free, maskless and resistless removal of silicon. As any electron-beam-induced processing is considered non-destructive and implantation-free due to the absence of ion bombardment this approach is also a potential method for removing focused-ion-beam (FIB)-inflicted crystal damage and ion implantation. We show that Cl(2)-FEBIE is capable of removing FIB-induced amorphization and gallium ion implantation after processing of surfaces with a focused ion beam. TEM analysis proves that the method Cl(2)-FEBIE is non-destructive and therefore retains crystallinity. It is shown that Cl(2)-FEBIE of amorphous silicon when compared to crystalline silicon can be up to 25 times faster, depending on the degree of amorphization. Also, using this method it has become possible for the first time to directly investigate damage caused by FIB exposure in a top-down view utilizing a localized chemical reaction, i.e. without the need for TEM sample preparation. We show that gallium fluences above 4 × 10(15) cm(-2) result in altered material resulting from FIB-induced processes down to a depth of ∼ 250 nm. With increasing gallium fluences, due to a significant gallium concentration close beneath the surface, removal of the topmost layer by Cl(2)-FEBIE becomes difficult, indicating that gallium serves as an etch stop for Cl(2)-FEBIE.

Gas-assisted etching and deposition with focused ion beams are unique and flexible methods for the fabrication of nanostructures. To understand and improve these processes the ability to accurately simulate and predict the resulting structures is very important. In this paper we present a nonlocal recoil-based algorithm for topography simulation of ion-beam induced gas-assisted deposition. We have fabricated flying roof like overhanging structures and found very good agreement between simulation and experiment. These structures cannot be explained with a local model. Furthermore, we demonstrate a considerable influence of the beam diameter on the resulting structure by comparing otherwise identical simulations with different beam diameter.

Focused ion beams are an established but inherently slow technique for many nanopatterning applications. One way to increase its processing speed is by gas-assisted ion-beam induced etching. However, to understand and improve this process, the ability to accurately simulate the precursor coverage is very important, because it strongly affects the efficiency of the process. In this paper, the authors present a recoils-based simulation model that considers precursor adsorption, decomposition, and diffusion. The authors provide a non-steady-state solution for translational symmetry, which they use to investigate the influence of the precursor diffusion coefficient on the etching process. They find that the diffusion coefficient influences the shape of the bottom of the irradiated structure. Furthermore, they compare the simulation results to experiments of SiO2 etched by XeF2 using a focused Ga ion beam, and extract model parameters such that the etching rate of numerous experiments with different current densities can be predicted accurately.

Nanoimprint lithography (NIL) has been established as a high-throughput technique to fabricate sub-25-nm patterns at a low cost. The fabrication of NIL templates with features in the submicrometer range is currently a bottleneck of the NIL technology. The replication of errors on NIL templates places a major challenge on the reusability of templates. Focused ion beam (FIB) technology is employed to modify prestructured NIL templates. In this work, repair strategies for NIL stamps are discussed. Excess material from stamps has been removed by ion milling. Nanoscale trenches and ultrathin lamellas fabricated with a focused ion beam and their corresponding imprints are presented. It has been confirmed that commercial UV-NIL stamps can be modified by FIB milling and imprinted line patterns were successfully replicated by UV-NIL using the repaired templates. Furthermore, the potential of three-dimensional NIL templates structured by FIB was evaluated. Three-dimensional imprints with features down to 80 nm with good structure conformity to the template were demonstrated. The capabilities and limitations of FIB as repair technology for NIL stamps are discussed.