To save this undefined to your undefined account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you used this feature, you will be asked to authorise Cambridge Core to connect with your undefined account.
Find out more about saving content to .
To save this article to your Kindle, first ensure email@example.com is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
We present the fabrication of a pixels structure by a well-defined pattern replication of a micrometer template driven by a surface free-energy lithographic technique, realized by molecular aggregation in dewetting conditions and by confining the liquid solution with geometric boundaries. The organization in the solid-state of the selected thiophene-based molecular materials allows to realize a bicoloured, green and red-emitting pixels structure, by exploiting the molecular structural arrangement, induced during a dewetting process, and the great conformational flexibility of DTT7Me.
Photoresist free photolithographic deposition of zirconium oxide from photosensitive zirconium complexes has been achieved using photochemical metal organic deposition. In this contribution, the deposition of patterned zirconium oxide is used as an example to demonstrate both negative and positive photolithographic deposition. In the prototypical deposition of zirconium oxide by photochemical metal organic deposition, a solution containing zirconium (IV) di-n-butoxide bis(2, 4-pentanedionate) was used to spin coat a silicon substrate, resulting in an amorphous film. The film was then exposed to UV light leading to the formation of zirconium oxide and other volatile products. The resultant zirconium oxide film was investigated by X-ray diffraction and Auger Electron Spectroscopy. Irradiating the precursor film through a photo mask led to a latent image which yielded either a negative or a positive pattern dependent upon developer. Subject to further photochemical or thermal treatment, a zirconium oxide pattern can be obtained. Similar results were obtained using a series of zirconium (IV) complexes. Both positive and negative patterns of zirconium oxide with 2 micron feature sizes were obtained.
The hot embossing of electron beam generated structures with linewidths 0.35-3.25 μm has been examined in biaxially-oriented polypropylene (BOPP). The individual test elements consisted of pixels of 30 x 30 μm with a specific configuration of symbols and lettering. The embossing of these features has been performed as a function of temperature (80-140 °C) and applied pressure (2-20 kPa). Significant increases in both embossed depth and sidewall angle was evident over the temperature range 100 to 130 °C with a leveling off at higher temperatures attributed to the onset of a regime of viscous liquid flow. At temperatures within this regime, a critical level of pressure was required to fill the mold features. Accurate embossing of medium and coarse lettering (0.50-0.65 μm linewidth) and geometric symbols (1.25-3.25 μm linewidth) has been demonstrated at a temperature of 130 °C and an applied pressure of 13 kPa. The finest lettering (0.35 μm linewidth) was incompletely embossed under these conditions.
Photo-acid generator (PAG) is the key component responsible for the increased sensitivity of chemically amplified resists in use today for microelectronics production. Concentration variation of PAG through the thickness of the photoresist film adversely affects materialís performance. To offset reduced acid concentration at the bottom of the resist, we have developed adhesion promoting photo acid generators, called as a class “APPAG” that enhance acid concentration at interface between the resist and the substrate. An overview on the preparation and characterization of two siloxane based APPAG materials along with a performance comparison of commercial DUV and EUV resists on APPAG is provided. Longer diffusion length photo-acid generator (APPAG 9) retained square profile of critical dimension (CD) at off-focus values and was found to give nearly a 50% improvement in depth of focus for 250nm node DUV lithography. For EUV lithography, both shorter diffusion length APPAG 6 and APPAG 9 were shown to substantially improve performance envelope for 100nm dense lines and spaces at reduced post exposure bake (PEB).
We performed combined thermal and ultraviolet nanoimprint lithography (TUV-NIL) using a recently developed nanoimprint polymer (mr-NIL 6000 from Micro Resist technology GmbH) and achieved an imprinted feature size of 50 nm. We used commercially available 2-inch-diameter transparent quartz molds (NIL Technology, Denmark and Obducat, Sweden) comprising 150 nm to 190 nm-deep features of various shapes and aspect ratios with lateral dimensions ranging between 50 nm and 300 nm. The imprint polymer was spun onto a silicon substrate, covered with an oxide layer. After the TUV-NIL step, residual polymer layers at the bottom of the imprinted features were removed by oxygen plasma etching. Imprinted patterns were then transferred into the silicon oxide layer underneath by reactive ion etching (RIE). In a final step the residual polymer was stripped off the silicon oxide surface in an oxygen asher. All imprinted features as well as the corresponding pattern transfer results showed good surface and sidewall characteristics.
We present a new and relatively simple process to manufacture three-dimensional sub-micron structures over square centimeter areas using a soft stamp imprinting process. The room-temperature replication process shows excellent quality in transferring features directly into inorganic silica material with pattern distortion smaller than 0.03% over an area of 15×15mm2. Using a self assembly planarization method the imprinting process can be repeated to form three-dimensional structures. As a demonstration, a multilayer stack of four crossed gratings is shown.
A capillary bridge printing technique has been used to deposit copper interconnects using homogeneous solutions of a Cu(II) precursor in a series of low boiling primary alcohols. The rheological properties of the solutions have been measured first to determine their printability. The as-printed lines with subsequent annealing at relatively low temperatures (∼200 °C), in order to evaporate the volatile solvents and facilitate dissociation of the precursor deposit, produced conducting interconnects. The precursor has been demonstrated to be self-reducing and requires no reducing environment (e.g. H2) thus making the interconnect formation easier. Moreover, successful decomposition of the precursor into metallic Cu at such low temperatures holds promise for applications involving flexible polymer substrates.
We report on two gas phase nanoparticle integration processes to assemble nanomaterials onto desired areas on a substrate. We expect these processes to work with any material that can be charged. The processes offer self-aligned integration and could be applied to any nanomaterial device requiring site specific assembly. The Coulomb force process directs the assembly of nanoparticles onto charged surface areas with sub-100 nm resolution. The charging is accomplished using flexible nanostructured electrodes. Gas phase assembly systems are used to direct and monitor the assembly of nanoparticles onto the charge patterns with a lateral resolution of 50 nm. The second concept makes use of fringing fields. The fringing fields directed the assembly of nanoparticles into openings. The fringing fields can be confined to sub 50 nm sized areas and exceed 1 MV/m, acting as nanolenses. Gas phase assembly systems have been used to deposit silicon, germanium, metallic, and organic nanoparticles.
In this paper, a method of direct electron beam lithographic deposition of metal and metal oxide films is demonstrated using metal organic complexes. In this method, a solution of a metal complex is used to spin coat a substrate to obtain a precursor film. The precursor film is then directly patterned by electron beam writing. A solvent is then used to develop the latent image. Using examples of titanium, tantalum, zirconium, and gold, we illustrate patterning of metal and metal oxide films and both positive and negative deposition. The feature size demonstrated is as low as 14 nm while the demonstrated aspect ratio is as high as 11.
The trend for the electronics industry to develop more functional, smarter and more compact devices has stressed the traditional manufacturing and packaging processes including the printing/dispensing technology. The traditional printing technique (e.g. time-pressure needle dispensing, screen printing, pin transfer and jetting) each has their own disadvantages in terms of dimensionality, accuracy, repeatability, flexibility and consistency, which have become the bottle neck of the industry. Enabling tools and technologies are greatly needed for the manufacturing and packaging of highly integrated and complicated parts and assemblies. In this paper, nScrypt will present novel pumping technologies and innovative printing/dispensing solutions for 21st century manufacturing and packaging. nScrypt's novel pump and robust system can dispense with precise volume control for tens of picoliter resolution, accurately place or align within a few microns, conformably print on exaggerated surfaces of tens of centimeters, and are flexible with materials and patterns. Dispensing of micro lines, dots, three-dimensional structures and conformal printing will be presented. This process has a wide range of applications including, but not limited to, conductors, resistors, optics, adhesives, sealants, frit, solders, encapsulates, wire bonding, underfilling, flip-chip bumping and 3-D structures.
The process of spin dewetting was used to fabricate polymer micro and nanostructures from poly(methyl methacrylate) (PMMA), poly (propyl methacrylate) (PPMA), and polystyrene (PS). Polymer structures were formed on poly(dimethylsiloxane) (PDMS) molds by dewetting of a polymer solution during spin coating. Features were removed from the mold using heat and pressure to transfer the polymer to silicon or glass substrates. By varying the coating conditions, a variety of different polymer feature morphologies were obtained for a given PDMS mold geometry. In this study, the ability to fabrication polymer micro and nanostructures using spin dewetting was demonstrated on a variety of PDMS mold geometries. The effects of polymer solution concentration and mold feature size on the resulting polymer structures were examined. In addition, microfabricated PMMA structures were used as etch masks for anisotropic etching of silicon in an aqueous solution of tetramethylammonium hydroxide (TMAH).
The ability to mass produce biosensor arrays at low costs is an important target for the diagnostics industry. Our group has previously explored the batch production of mesoscale sized hydrogels as platforms for biosensors using photolithographic techniques. The individual hydrogel features were self-assembled through lateral capillary interactions to form a closed packed configuration and the pre-polymer medium was subsequently UV-cured to form the array. To understand the self-assembly dynamics, we investigated, through simulation, the flotation behavior of two assembling particles and its dependence on physical constants such as surface tension and particle density. Simulation results revealed that the objects tilt toward each other as they came into proximity. The tilt angle decreased with increasing surface tension but increased with increasing particle density. Understanding the details of the flotation behavior is necessary in the development of a full scale self-assembly model.
A method for the fabrication of piezoelectric polyvinylidene fluoride (PVDF) microstructures is described. Embossed and individual features with highly defined geometries at the microscale were obtained using soft lithography-based techniques. Various structure geometries were obtained, including pillars (three different aspect ratios), parallel lines, and criss-crossed lines. SEM characterization revealed uniform patterns with dimensions ranging from 2 μm ñ 15 μm. Human osteosarcoma (HOS) cell cultures were used to evaluate the cytocompatibility of the microstructures. SEM and fluorescence microscopy showed adequate cell adhesion, proliferation, and strong interaction with tips and corners of the microdiscontinuities. Microfabricated piezoelectric PVDF structures could find applications in the fabrication of mechanically active tissue engineering scaffolds, and the development of dynamic sensors at the cellular and subcellular levels.