Marek Skupinski

Well-ordered nanopore arrays in rutile TiO2 single crystals by swift heavy ion-beam lithography

Ion track lithography has been applied for transferring the self-ordered nanopattern of porous anodic alumina to single-crystalline rutile TiO2 substrates. As a result, nanometre resolved arrays have been fabricated with an aspect ratio ranging from 5 to 16, over areas of several square millimetres. Differences in the expected aspect ratio of the resulting nanopores in rutile TiO2 single crystals are analysed and discussed. Some of these differences may be ascribed to varying densities of the mask material.

Fabrication of high-density ordered nanoarrays in silicon dioxide by MeV ion track lithography

Self-assembled nanoporous alumina films were employed as masks for MeV ion track lithography. Films with thickness of 2 μm and pore diameters of 30 and 70 nm were attached to thermally grown SiO2 covered with a thin gold layer. The samples were aligned with respect to the beam by detecting backscattered He+ ions with the initial energy of 2 MeV. The ordered pattern of the porous alumina films was successfully transferred into SiO2 after irradiation with a 4 MeV Cl2+ beam at fluence of 1014ions∕cm2, followed by chemical etching in a 5% HF solution.

Nanopattern transfer to SiO2 by ion track lithography and highly selective HF vapor etching

The authors present a method for high aspect ratio nanopatterning of high density (1010pores∕cm2) self-assembled porous alumina membrane pattern into thermally grown SiO2 on silicon. The pattern transfer is accomplished by irradiating through 2μm thick porous alumina membrane with swift heavy ions (4MeV Cl2+). Ions passing through the nanopores in the mask at a fairly high fluence (typically 1014ions∕cm2) are impinging on the substrate and creating a continuous volume of overlapping ion tracks of damage. The damage is sufficient to be selectively etched by HF vapor from an aqueous HF solution. From an alumina mask with pores of 70nm diameter, a pattern of pores of 77nm in diameter and the same distance of 100nm between the centers of the pores was transferred. The deepest observed etched pores were 355nm, giving an aspect ratio of 5, which is up to 40 times larger compare to earlier work where HF wet etching was used. This ion track lithography technique shows a potential to produce nanostructures with ev...

Improved CIGS modules by KF post deposition treatment and reduced cell-to-module losses

The significant gain in efficiency by a KF post deposition treatment (PDT) on small cells, observed by several groups, can be scaled to full size modules. This is shown here by a significant gain for full size modules with KF PDT and a module reaching 17.2% (aperture area efficiency, externally confirmed). Another important topic is reducing the cell-to-module losses. Two different methods are presented and compared, a metal grid on top of the TCO and an improved TCO (ZnO:B). A sub-module (300×275 mm2) reaching 17.6% efficiency and a mini-module (50×50 mm2) reaching 18.7% efficiency is presented and confirms the reduction of cell-to-module losses.

Swift Heavy Ion Beam-Based Nanopatterning Using Self-Assembled Masks

Swift heavy ion beam-based lithography using masks of self-assembled materials has been applied for transferring well-ordered micro- and nanopatterns to rutile TiO2 single crystals. As the induced damage has a high etching selectivity the patterns can be developed in HF with very high contrast. Here we present resulting patterns when using a mask of self-ordered silica spheres. Since the obtained structures are replicas of the mass distribution of the applied mask, the shape and size of resulting structures depend on the geometric configuration of the silica sphere layers. In addition, the resulting pattern can be tuned by varying the applied ion energy and fluence. Direct modifications of the optical properties of TiO2 in a well-defined pattern are also presented.

Ion track lithography: novel low-cost process to form deep vertical and high aspect ratio MEMS in flexible laminates

High aspect ratio microstructures are today of utterly importance in MEMS. The process described in this paper can be used to produce deep, vertical microstructures in polyimide based materials, used in e.g. flexible printed circuit boards (FPCBs). Stacked polyimide and metal layers have the potential of integrating microelectronic circuits with above applications. The process is capable of producing regions with perpendicular sub-micron metal wire connections at numerous, arbitrarily specified locations. The flexible laminate is irradiated with heavy ions creating a vertical damage anisotropy (ion tracks) in the polymer layer. Lithographically defined apertures in the metallic layer define the geometry. The tracks exposed are selectively developed forming nanometer-wide pores. Metallic structures have been replicated in these pores by electrodeposition of metals. Demonstrator microstructures and highly vertical, through hole microvias have been fabricated. Ion track technology is promising for ultra-high density via batch production and has a potential of further miniaturizing via dimensions.