Maskless Patterning Technique Research Articles

Area-Selective Chemical Vapor Deposition of Gold by Electron Beam Seeding.

Chemical vapor deposition (CVD) is an established method for producing high-purity thin films, but it typically necessitates the pre- and post-processing using a mask to produce structures. This study presents a novel maskless patterning technique that enables area-selective CVD of gold. A focused electron beam is used to decompose the metal-organic precursor Au(acac)Me2 locally, thereby creating an autocatalytically active seed layer for subsequent CVD with the same precursor. The procedure can be included in the same CVD process without the need for clean room lithographic processing. Moreover, it operates at low temperatures of 80°C, over 200K lower than standard CVD temperatures for this precursor, reducing thermal load on the specimen. Given that electron beam seeding operates on any even moderately conductive surface, the process does not constrain device design. This is demonstrated by the example of vertical nanostructures with high aspect ratios of ≈40:1 and more. Written using a focused electron beam and the same precursor, these nanopillars exhibit catalytically active nuclei on their surface. Furthermore, by using the onset of the autocatalytic CVD growth, for the first time the local temperature increase caused by the writing of nanostructures with an electron beam can be preciselydetermined.

Mask-Free Patterned Perovskite Microcavity Arrays via Inkjet Printing Targeting Laser Emission.

Perovskite materials are promising candidates for the implementation of electrically pumped lasers considering the enhanced performance of perovskite-based light-emitting diodes. Nonetheless, current methods of fabricating perovskite optical microcavities require complex patterning technologies to build suitable resonant cavities for perovskite laser emission, burdening the device structure design. To address this issue, we applied inkjet printing, a maskless patterning technique, to directly create spontaneous formations of polycrystalline perovskite microcavity arrays to explore their laser-emitting action. The substrate surface tension was tuned to modulate the perovskite crystallization process in combination with optimization of printing ink recipes. As a result, polycrystalline perovskite microcavity arrays were achieved, contributing to the laser emission at 528 nm with a lasing threshold of 1.37 mJ/cm2, while simultaneously achieving high-definition patterning of flexible display. These results clearly illustrate the efficiency of inkjet printing technology in the preparation of polycrystalline perovskite optical microcavities and promote the development of flexible laser arrayed displays, providing a facile process toward the realization of perovskite-cavity laser devices.

Controlling Ag microfibres during the electrospinning process using a manipulated electric field for the maskless patterning of transparent conductive electrodes

A novel and facile electrospinning method is presented to fabricate transparent conductive electrodes (TCEs) on the intended area without the use of a physical medium, such as a stencil mask. By applying two different voltages to the ground and underground collectors, the electric fields between the nozzle-to-ground and nozzle-to-underground collectors are manipulated and the jet path of silver (Ag) microfibres can be significantly deflected towards where Ag microfibres are required. Using the developed electrospinning method, full-area TCEs are fabricated without using electric field manipulation for understanding the baseline performance. They exhibit a lowest sheet resistance (Rs) of 0.62 ± 0.19 Ω/sq with optical transmittance (T%) of 86.69 ± 1.55, and the highest T% of 94.76 ± 0.87 with Rs of 20.90 ± 0.45 Ω/sq. For demonstrating the capability of the developed electrospinning method, localised TCEs are fabricated by regulating the electric field between the nozzle-to-ground and nozzle-to-underground collectors, thereby controlling the deposition region of the Ag microfibres on the substrate; the approximate Rs of each localised TCE pattern is well below 15 Ω/sq. The shortest separated gap between localised TCEs is 466.23 μm on average, achieved by electric field manipulation without the use of a physical medium. Using this maskless patterning technique, solar media façades are demonstrated, and their relative performance is found to be as high as 96.28% with respect to bare solar modules.

Maskless micropatterning of electrochromic nanoparticles using a focused electron beam

Optical properties of electrochromic (EC) materials can be reversibly changed under applied voltages through electrochemical redox reactions. Prussian blue (PB) is a well-known EC material that changes color from blue to colorless and transparent, and vice versa. Fine patterning of PB particles on a transparent substrate could lead to the development of a high-quality display device with very low energy consumption. In this paper, a maskless patterning technique using a focused electron beam is described, and the effects of the accelerating voltage and the electron dose are studied. The results show that the micropatterning of PB particles is achieved at an accelerating voltage of 5 kV and at electron doses of 10–100 C/m2. Reversible changes in color were observed between blue and colorless–transparent after the patterning of PB particles.

Maskless patterning of borosilicate glass surface using nanoindentation-induced etch-hillock phenomena

A maskless patterning technique of borosilicate glass surface was studied by combining nanoindentation with HF isotropic etching. Effects of the process parameters (etch time, normal load, loading/unloading rate, and indentation hold-time under the maximum load) on the morphologies of the indented surfaces before and after etching were investigated. An indented borosilicate glass surface protruded rather higher than the initial height of the surface after etching in 50 wt% HF. The initial shape of the etch-hillock structure was the reversed image of the indent. As the etch time increased, the morphology of the etch-hillock structure gradually became round due to the isotropic etching property. The size of the etch-hillock structure was increased with increasing normal load. However, when the normal load was very small, the etch-hillock phenomena were not observed, because there was little plastic deformation, due to an indentation size effect. Conversely, the size of the etch-hillock structure did not vary despite the change of the loading/unloading rate or hold-time under the maximum load. With respect to deformation energies, the size of the etch-hillock structure was in proportion to the size of plastic deformation energy. By using this technique, sample characters were successfully written on the glass surface.

Maskless Patterning of Mo and Si by Focused Ion Beam Implantation

ABSTRACTMaskless patterning of Mo and Si was done by implanting 50 keV focused Ga+ ion beam and by plasma etching using CF4 gas. The implantation is done to modify the chemical properties of the sample surface. It was found that Mo films became etch-resistant for the plasma etching after implantation at a dose higher than 4×1015 /cm2. Si crystals showed a positive tone pattern due to a radiation enhanced etching at a dose lower than 5x1016/cm2. At higher doses, the etching rate decreased and above 8 x 1016/cm2, no etching was observed in the implanted region. Patterns with a thickness of a several hundred nanometers were formed by the present maskless patterning technique.

Recent Advances in The Application of Focused Ion Beams

Recent advances of focused ion beam systems and their applications are presented. The applications include maskless ion implantation and various maskless patterning techniques which make use of ion induced chemical effects. These are ion beam assisted etching, deposition and ion beam modification techniques and are promising to improve patterning speed and extend applications of focused ion beams.

Ion beam microfabrication

Various maskless patterning techniques using focused ion beams are reviewed. These are ion beam assisted etching of Si and GaAs, ion beam modification technique for patterning Cr films and ion beam assisted depositions of Al films. It is shown that use of ion beam induced chemical effects is important to extent applications of focused ion beams.

Maskless Patterning of Cr Films Using Focused Ion Beams

ABSTRACTCharacteristics of maskless patterning of Cr films using focused Sb+ ion implantation have been investigated. Dose and depth dependence of the etching rate of Sb-implanted layers during plasma etching using CCl4 were measured. Sb profiles were also measured by Rutherford backscattering techniques. It was found that a sharp threshold dose exists to form an etch-resistant layer by Sb implantation. It was also found that a latent image of an Sb implanted pattern at a dose ≥3.8×1015/cm2 was developed by the plasma etching, and that Cr patterns with a thickness of a few hundred nanometers were formed by the present maskless patterning technique.