Multi-Material Ink Direct Writing System with Material Switching Optimization

Electron beam (EB) direct writing is expected to play an important role in the field of lithography for manufacturing future advanced ULSIs. Cell projection techniques are of particular interest, which may make the EB direct writing system practical for use in ULSI memories with many repeated patterns. However, the proximity effect of such systems disturbs the formation of fine 0.2 µ m level patterns throughout the patterning area. In order to solve this problem, we have developed an improved proximity effect correction technique suitable for use in a cell projection EB direct writing system. This technique makes use of smaller cell projection shot (CPS) size in the edge region than in the center region in the EB direct writing area with dose compensation between CPSs, based on the self-consistent method. Utilizing this technique, we can obtain fine 0.2 µ m patterns with 0.02 µ m critical dimension (CD) control patterns, which are required to manufacture 1Gbit dynamic random access memories (DRAMs).

The increasing demand for micro- and nanofabrication and in parallel the increasing requirements on feature size and resolution is leading to an enormous growth in the field of multi-photon three-dimensional fabrication. To enable new and diverse investigations in this field and to enable high precision for nanofabrication on large areas, a high precision positioning system is combined with an ultra-short pulse laser system. The aim is a modular setup with constant adherence to the Abbe-comparator principle in order to achieve systematic improvements in the area of Direct Laser Writing. For a high-quality identification of the microstructures a measurement tool based on atomic force microscopy is used. To enable the fabrication of continuous micro- and nanostructures on large area, an extremely high positioning precision is used, where no further stitching methods are necessary. Therefore as base of the Direct Laser Writing system the nanopositioning and nanomeasuring machine (NMM-1) is used, which was developed at Technische Universität Ilmenau together with SIOS Meßtechnik GmbH, with a positioning volume of 25 mm × 25 mm × 5 mm and a positioning resolution in the sub-nanometer range. First investigations already confirmed that microfabrication with a Femtosecond Laser and the NMM-1 could be realized and showed the possibility of further developments in the field of Direct Laser Writing. Now the modular structure as a research platform is designed in such a way that the various extensions and measurement setups for large-scale investigations can always be implemented in a metrologically traceable manner. The presented work shows the development of a modular functional setup of an exposure system and NMM-1, which enables micro- and nanofabrication and an improvement in the structure size over large areas.

Direct UV laser writing system to photolithographically fabricate optimal microfluidic geometries: Experimental investigations

In this work a developed experimental setup for the direct laser writing (DLW) system of a photolithography mask for integrated photonics devices will be described. The DLW system is mainly composed of a pulsed Nd:YAG laser source, beam handling system, (X-Y) table, PC computer, CCD camera and TV monitor. The synchronization between the laser source and the (X-Y) table is achieved by a NI Instruments and LabVIEW based program. The experimental micromachining results from some samples of continuous writing lines obtained by removal of chromium deposited on glass substrates will be presented and discussed.

The development of photonic-integrated circuits (PICs) for data communication, sensing, and quantum computing is hindered by the high complexity and cost of traditional fabrication methods, which rely on expensive equipment, limiting accessibility for research and prototyping. This study introduces a Direct Laser Writing (DLW) system designed as a low-cost alternative, utilizing an XY platform for precise substrate movement and an optical system comprising a collimator and lens to focus the laser beam. Operating on a single layer, the system employs SU-8 photoresist to fabricate polymer-based structures on substrates such as ITO-covered glass. Preparation involves thorough cleaning, spin coating with photoresist, and pre- and post-baking to ensure material stability. This approach reduces dependence on costly infrastructure, making it suitable for academic settings and enabling rapid prototyping. A user interface and custom slicer process standard .dxf files into executable commands, enhancing operational flexibility. Experimental results demonstrate a resolution of 10 µm, with successful patterning of structures, including diffraction grids, waveguides, and multimode interference devices. This system aims to transform PIC prototype fabrication into a cost-effective, accessible process.

We have developed a Character Projection (CP)-type, low-energy Electron-Beam Direct Writing (EBDW) system for a quick turnaround time and mask-less device fabrication of small production lots with a variety of designs. The exposure time has been decreasing because the irradiation time of electrons is being reduced by development of high-sensitivity resist and by decrease in the number of EB shots with the CP method, and the amplifiers of the deflectors have attained specifications required by EBIS. In order to further increase the throughput, overhead time, that is, the exposure waiting time, must be shortened. This paper describes our strategy for reducing the exposure waiting time. The reduction ratio of the exposure waiting time was about 60% and the throughput was increased about 20%.

In this work, two AM technologies were utilized to compare the effectiveness of fabricating a simple electronic device with a conductive trace and hollow cylinder representative of ‘printed packaging’ that would survive harsh environmental conditions. The printed packaging cylinder delineates printed potting for electronics packaging. An nScrypt direct write (DW) system was the primary manufacturing system but a developing technology—coined large area projection sintering (LAPS)—manufactured a subset of samples for comparison. The tests follow Military Standard (MIL STD) 883 K and include resiliency evaluation for die shear strength, temperature cycling, thermal shock, and high G loading by mechanical shock. Results indicate DW Master Bond epoxy devices show resilience to extreme temperatures, thermal shock, and mechanical shocks while also surpassing the die shear strength failure criteria specified by the MIL STD. LAPS sintered Nylon devices also show mechanical resilience to thermal shock and surpass the die shear strength failure criteria. However, there were some open circuits, increases in resistance, and delamination when LAPS Nylon devices were subjected to extreme temperatures and 20 000 G shock loading normal to the substrate. The thermal effects are likely due to the thermal expansion mismatch between Nylon and the conductive paste while the mechanical shock effects may be attributed to the geometry differences of the LAPS Nylon printed packaging. Further studies are required to understand these failure modes in some of the LAPS Nylon samples and refine the process to address them.

A modified SEM type electron beam exposure machine adopts an auto‐registration function and it is converted to a direct writing purpose system. One‐chip‐one field and chip‐by‐chip registration scheme is adopted to increase the field size and to eliminate stage‐related problems, such as laser interferometric control complexity and stage movement slowness. 2 μm rule 64 k ROM, shrunk to 4/10 from the original design, is used as a device for testing the developed EB system capability. 0.8 μm high, 2 μm wide, L‐shaped step made from bulk Si is used as registration marks and ±0.1 μm of 2 level overlay accuracy is achieved. Although no special optimization or device design modification is done on the shrinkage, the device fabricated by all EB direct writings and dry etching process shows no noticeable difference in electric functions from one made by photolithographic (DSW) processes. The system is stable without intensive maintenance jobs and overlay accuracy through the process (7 exposing levels) is better than ±0.25 μm, although the registration mark structure is changed by the fabrication processes. It becomes clear that this kind of direct writing machine is very useful for research of EB lithography and the LSI development.

This study demonstrated our prototyped Micro Electro Mechanical System (MEMS) electron emitter which is a nc-Si (nanocrystalline silicon) ballistic electron emitter array integrated with an active-matrix driving LSI for high-speed Massively Parallel Electron Beam Direct Writing (MPEBDW) system. The MPEBDW system consists of the multi-column, and each column provides multi-beam. Each column consists of emitter array, a MEMS condenser lens array, an MEMS anode array, a stigmator, three-stage deflectors to align and to scan the multi beams, and a reduction lens as an objective lens. The emitter array generates 100x100 electron beams with binary patterns. The pattern exposed on a target is stored in one of the duplicate memories in the active matrix LSI. After the emission, each electron beam is condensed into narrow beam in parallel to the axis of electron optics of the system with the condenser lens array. The electrons of the beams are accelerated and pass through the anode array. The stigmator and deflectors make fine adjustments to the position of the beams. The reduction lens in the final stage focuses all parallel beams on the surface of the target wafer. The lens reduces the electron image to 1%-10% in size. Electron source in this system is nc-Si ballistic surface electron emitter. The characteristics of the emitter of 1:1 projection of e-beam have been demonstrated in our previous work. We developed a Crestec Surface Electron emission Lithography (CSEL) for mass production of semiconductor devices. CSEL system is 1:1 electron projection lithography using surface electron emitter. In first report, we confirmed that a test bench of CSEL resolved below 30 nm pattern over 0.2 um square area. Practical resolution of the system is limited by the chromatic aberration. We also demonstrated the CSEL system exposed deep sub-micron pattern over full-field for practical use. As an interim report of our development of MPEBDW system, we evaluated characteristics of the emitter array integrated with an active-matrix driving LSI on the CSEL system in this study. The results of its performance as an electron source for massively parallel operation are described. The CSEL as an experimental set consisted of the emitter array and a stage as a collector electrode that is parallel to the surface of the emitters. An accelerating voltage of about -5 kV was applied to the surface of the emitter array with respect to the collector. The target wafer and the emitter array were set between two magnets. The two magnets generated vertical magnetic field of 0.5 T to the surface of the target wafer. A gap between the emitter array and the target wafer was adjusted to a focus length depending on electron trajectories in the electromagnetic field in the system. The emitter array projected 100x100 electron beams with binary patterns and a dots image of its original size on the target wafer. The certain array was examined in order to evaluate the property of the e-beam exposure.

Direct writing(DW) is a method of patterning materials to a substrate directly, without a mask. It can use a variety of materials and be applied to various fields. Among DW systems, the flow-based type, using a syringe pump and nozzle, is simpler than other types. Furthermore, the range of materials is exceptionally wide. In additive processes, a three dimensional structure is made of stacking layer. Each layer is made of several lines. In this regard, good surface roughness of fabricated layers is essential to three dimensional fabrication. The surface roughness of any fabricated layer tends to change with the dispensing pattern. When multiple layers fabricated by a nozzle dispensing system are stacked, control of the nozzle position from the substrate is important in order to avoid interference between the nozzle and the fabricated layer. In this study, a fluid direct writing system for three dimensional structure fabrication was developed. Experimentsto control the position of the nozzle from substrate were conducted in order to examine the characteristics of the material used in this system.

Electron Beam Direct Writing (EBDW) has been applied to various applications such as prototyping or small amount production of electronic devices. Originally, proximity effect in EBDW is considered as the problem of the background energy difference caused by the pattern density distribution. However, the critical dimensions of target patterns are getting smaller, we cannot ignore influences of the forward scattering. Theoretically, when the critical dimension is close to 3 or 4 times of forward scattering range, influence cannot be ignored. For example, in case ofthat corresponds, fabricating 20 nm dimension patterns by Nano Imprint Lithography (NIL) which is significant candidate of next generation lithography technology. Because it requires original dimension (1:1) mold. Therefore proximity effect correction (PEC) system which considers the forward scattering must be important. We developed simulation-based proximity effect correction system combined with data format conversion, works on Linux PC cluster. And we exposed the patterns which are dose compensated by this system. Firstly, we have speculated parameters about backward scattering parameters by exposing 100 nm line and space patterns. We got following parameters, beta (backward scattering range) = 32 urn, eta (backward scattering coefficient) = 2.5. Secondary, we have exposed Line and Space patterns whose dimensions are from 20 nm to 100 nm. We found that smaller and dense patterns have trend to be over exposed and bigger. Experimental specification is following, EB Direct Writing system is JBX-9300FS (lOOkeV ace. Voltage) by JEOL co.ltd, (Japan) , resist is HSQ (FOx 12) by Dow Coming co. (United States), substrate is Si.

A high energy 50-kV electron beam direct writing system which has a gas introduction line has been developed. Several aspects of the performance of this system are demonstrated. The electron beam size has been improved to be less than 5 nm. 10-nm width line patterns with 50-nm periods in PMMA resist on a thick Si substrate are demonstrated. It is observed that fewer proximity effects occur when a high-energy electron beam is used. 20-nm-width lines and 20-nm-diameter Au-Pd metal patterns have been fabricated by a lift-off method. 14-nm-diameter carbon dot patterns were deposited on a Si substrate by electron-beam-induced deposition using Styrene gas.

In this study, a novel laser direct synthesis and pattering technology is applied in conjunction with an A&F XXY alignment platform to rapidly fabricate flexible conductors on a polymer substrate (polyimide film) with designated patterns. In the process, a focused continuous wave green laser was focused onto the polymer substrate that is mounted and directed using the XXY alignment platform. The focused laser energy absorbed by the polymer substrate is used to heat the transparent and particle-free reactive silver ink on the polymer substrate surface. With appropriate programing of the XXY alignment platform motion to control the laser scanning parameters, silver patterns with good electrical conductivity were successfully obtained. This technology can be operated directly at atmospheric pressure and room temperature. It does not require the use of vacuum chamber, oven and photo-mask, etc. Therefore, this novel technology and system offers a new approach to the cost-effective and green fabrication for flexible electronics. The compact size and excellent stability of the XXY alignment platform make the fabrication system even more competitive. In particular, the programmable small radius plane rotation function of the XXY alignment platform provides flexibility in the pattern design with turnings while keeps the uniformity of the resulted micro metal lines.

Laser Direct Writing System (LDWS) is a key equipment for manufacturing the binary optical masks. A polar coordinate laser direct writing system was developed and the maximum mask size which can be made is 4 inches. One of its main properties, namely lithography resolution, was analyzed based on the optical intensity distribution in the photoresist. Normally, 0.86 micrometer linewidth on masks can be achieved. In some special case, a super resolution of 0.5 micrometer linewidth can also be obtained, and it will require a more rigorous exposure latitude. The exposure experiment results on LDWS showed good agreement with the theoretical calculations. The approach by using the optical intensity distribution in the photoresist to predict the relations between linewidths and exposure latitude gives out a simple and clear image about the effects of photoresist on lithographic linewidths.

Due to the high cost-effectiveness, extra flexibility, and short production cycle, laser direct writing system as a kind of maskless lithography technology has been widely used in the fields of micro-nano-manufacturing. The working principle of the parallel laser direct writing system based on DMD(Digital Micromirror Device) is introduced. A novel negative photoresist -- dry film photoresist is adopted into the study of deep etching for the fabrication of the micro mold. The experimental results show that: the whole process is convenient, efficient and flexible; the precision of the 2-D patterning and the depth of etching is reliable.