Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XXX

Femtosecond laser processing in GHz- and MHz-burst mode has attracted much attention in the last years. In this contribution, we report on pump-probe shadowgraphy of glass drilling with a temporally shaped femtosecond laser beam operating in both the MHz-burst and the GHz-burst regime. We were able to measure the luminescence time of the plume in both operating regimes and compare it to the regime of standard repetitive single pulses. Moreover, we monitored the plume behavior during the drilling process of through holes.

Ultrafast lasers have emerged as the most promising tool for fabricating high-aspect-ratio holes in glass, essential for modern microelectronics. The most popular fabrication techniques based on ultrashort pulses include percussion drilling, rear-side ablation, and selective laser etching that involves aggressive chemicals. This study highlights advancements in through-glass vias (TGV) fabrication using rear-side ablation and percussion drilling with a focus on processing time optimization. We demonstrate the capability of taper-free fabrication of high-aspect-ratio holes, addressing a common challenge in subtractive laser processing. By fine-tuning laser parameters and employing optimized processing strategies, we achieve hole diameters of less than 100 μm with an aspect ratio over 1:20. Besides the rear-side ablation process, we show the influence of pulse energy and MHz burst mode on the depth of microholes fabricated in the glass. The results were achieved using a laser source generating 200 uJ energy in a single pulse and up to 400 uJ burst energy at a wavelength of 1030 nm (Jasper X0, Fluence, Poland).

Through-Glass Vias (TGVs) are crucial in semiconductor and electronics industries, enabling high-density interconnections in devices from automotive sensors to Micro-Electro-Mechanical Systems. They support device miniaturization and improve electronic package performance by enabling vertical electrical connections through glass substrates. Femtosecond laser pulses can drill transparent materials like glass with minimal thermal effects, though throughput and aspect ratios can be limiting factors. Our research investigates femtosecond laser burst modes in the GHz regime for percussion drilling of materials such as fused silica, diamond, silicon carbide, and sapphire. We found that long, well-formed channels can be produced, in some cases reaching into tens of millimeters with an aspect ratio of 1:100, outperforming conventional single-pulse techniques. These results indicate increased micromachining efficiency for TGVs and potential applications in advanced optics, biomedical devices, and beyond, demonstrating the enhanced performance of GHz burst mode femtosecond laser machining.

Femtosecond laser technology is under constant development, aiming to increase the versatility of the systems and unlock new application areas. One of the recent advancements in femtosecond laser technology is the implementation of burst mode, allowing the laser to output tightly packed femtosecond pulse trains with repetition rates in the MHz and GHz range. This mode not only increases process throughput by dividing a high-energy single pulse into multiple ones but also realizes the formation of high aspect ratio, low degree taper, through-glass vias (TGVs) in glass substrates. TGVs in glass substrates are important for semiconductor applications, particularly in chip packaging, as these substrates with holes can reduce manufacturing costs and by eliminating the need for insulating layers. In this study, we present the capabilities of the FemtoLux 30 femtosecond laser operating in MHz and GHz burst modes, in producing high aspect ratio, low degree taper TGVs in various glass substrates.

We present a micro-via fabrication technology for glass materials using KrF excimer laser direct ablation drilling. In this study, we present results demonstrating high productivity, achieving more than 1000 micro-vias per second on glass substrates using an excimer laser and a diffractive optical element (DOE). This high productivity is further enhanced by the pulse shape (time-domain) formation of the excimer laser. We show a 2.2-fold increase in ablation rate by extending the laser pulse width from 32 ns TIS to 130 ns TIS. We analyzed and identified the mechanism of this productivity enhancement by observing the emission light during ablation using a high-speed spectrometer and a high-speed camera. Gigaphoton demonstrates that the combination of excimer laser pulse formation and DOE technologies enables high-productivity fabrication of fine micro-via holes for high-performance advanced packaging.

This research addresses the growing need for advanced data storage technologies due to the lack of reliable and effective alternatives to traditional media. Utilizing ceramic coatings on thin glass with femtosecond laser technology, we developed a cost-effective, energy-efficient Write-Once-Read-Many (WORM) data storage solution. The technique uses laser ablation to store data as physical matrices on ceramic-on-glass sheets, achieving high writing and reading speeds via parallelization with MOEMS and GigE devices. A working prototype demonstrated the technology's potential and promising media lifetime estimates, offering a sustainable and viable alternative to current data storage methods.

Femtosecond Laser Irradiation followed by Chemical Etching is exploit to create microfluidic devices for the fabrication of integrated devices for High order Harmonic in noble gas, exploiting the hollow core waveguide approach. More complicated functionalities like polarization controller, beam splitting or interferometers are also demonstrated. We envisage that the high adaptability of our microfluidic approach will pave the way to compact EUV beamlines Acknowledgments: European Union Horizon 2020 Research and Innovation Program under Grant Agreement No. 964588 (XPIC),.

Reliable industrial femtosecond lasers deliver pulse durations from 200 fs to 1000 fs. External pulse compression can shorten these pulses to below 100 fs with about 90% efficiency. In a basic study, we demonstrated improved edge quality in glass using 60 fs pulses at a 1030 nm wavelength and 800 kHz repetition rate. For sapphire (28 W) and fused silica (23 W), energy-specific volumes remained close to those of longer pulses, at 8 µm³/µJ and 6.5 µm³/µJ, respectively. We will extend this study to materials like Borofloat 33 and SF2, optimizing surface roughness, stress-induced birefringence, and minimum structure dimensions for sapphire and fused silica as well. These results will be compared to standard 310 fs experiments with IR (1030 nm), green (515 nm), and UV (343 nm) radiation. Additionally, we will investigate pulses as short as 30 fs, frequency-doubled 60 fs pulses and burst mode, focusing on edge quality, surface roughness, and stress-induced birefringence.

The utilization of femtosecond laser processing in Gigahertz (GHz)-burst mode has garnered considerable attention due to its potential for significantly enhancing ablation efficiency. Our study explored the application of GHz bursts in femtosecond laser polishing of glass. We have demonstrated controllable material removal with nanometer precision for the first time while maintaining sub-nanometer surface roughness. This achievement highlights the potential of femtosecond GHz pulse bursts in achieving high throughput optics fabrication.

Meta-optics involves controlling electromagnetic wave propagation using structures at or below the wavelength scale. The terahertz frequency region is gaining interest in applications in sensing, imaging, wireless communications, and radio astronomy. Traditional lithography, used to create these microstructures, requires multiple devices and clean-room environments, which are costly and struggle with non-uniform heights. As an alternative, ultra-short pulse laser processing offers a single-equipment solution. This method, using galvanometer mirrors, achieves a beam focus diameter of 10-20 um, smaller than terahertz wavelengths (hundreds of um), enabling the fabrication of sub-wavelength structures for THz meta-optics. We have successfully used femtosecond laser processing to create terahertz meta-lenses demonstrating comparable performance to lithographic methods, as well as anti-reflection moth-eye structures. This talk will show these advancements in terahertz meta-optics using ultrashort pulsed lasers.

Since the groundbreaking achievement of ignition and self-sustaining fuel burn at the U.S. National Ignition Facility (NIF), the field of fusion, specifically laser inertial fusion energy (IFE), has rapidly accelerated and transformed. Numerous countries are investing more heavily or initiating new fusion programs, with significant collaborative efforts from international research institutions and the private sector accelerating the path to practical fusion energy. The implications for the photonics market include an increased demand for lasers, optics, optical materials, diagnostics, and other key technologies, creating new opportunities for photonics companies and shifting market dynamics. Future challenges and strategies for achieving higher energy yields and commercial viability are outlined, emphasizing the critical role of photonics in enabling the next generation of fusion energy solutions.

The interaction of light and matter can create bonding structural and morphological changes in nano/micro-scale from the surfaces of diverse materials, sometimes even deep within them. This feature has been utilized in laser processing to produce new value for both science and industry. Recent advances in high-power, ultrashort pulsed laser and fast beam delivery technologies are rapidly expanding the possibilities of laser processing. At the same time, the number of parameters to be controlled has become enormous, which is why we have introduced Data Science. In this talk, we will discuss new data-driven laser processing utilizing high-speed data acquisition and AI data optimization for higher throughput and quality. We also aim for this technology to contribute to sustainable manufacturing and society in the future.

Optical frequency combs have revolutionized time and frequency metrology by providing rulers in frequency space that measure large optical frequency differences and/or straightforwardly link microwave and optical frequencies. One of the most successful uses of frequency combs beyond their original purpose has been dual-comb interferometry. An interferometer can be formed using two frequency combs of slightly different line spacing. Dual-comb interferometers without moving parts have no geometric limitations to resolution, therefore miniaturized devices using integrated optics can be envisioned. Dual-comb interferometers outperform state-of-the-art devices in an increasing number of fields including spectroscopy and holography, offering unique features such as direct frequency measurements, accuracy, precision, and speed.

Today, approximately 12,000 satellites orbit Earth. By 2030, estimates show numbers above 60,000. Today, we service spacecraft when absolutely necessary. By 2030’s, in-space services will be routine; refueling, repair, relocation, assembly, and manufacturing. Advances are underway to realizing this future, enabling a sustainable version will require photonics technologies.

Additively manufactured flexible hybrid electronics (FHEs) have emerged as a remarkable technology due to the simple, cost-effective fabrication, reduced e-waste, and development of multifunctional devices. The current prinitng ecosystem mainly relies on ink-based technologies such as inkjet and aerosol jet printers, which suffer from expensive and time-consuming formulation procedures, contaminations, and limited materials sources, making it challenging to print pure and multimaterial devices. This talk demonstrates a novel multi-laser-based additive nanomanufacturing (ANM) technique that allows dry, pure, solvent-free printing of various functional materials devices on different substrates.

Laser-based metal additive manufacturing (laser powder bed fusion and directed energy deposition) can manufacture geometrically and compositionally complex metal components directly from digital models without the design constraints of traditional manufacturing routs, which has potential to revolution many industries. However, laser-based metal additive manufacturing technologies still face critical challenges of (1) hard to predict and still relying on “trial and error”, (2) containing many uncertainties, (3) low fatigue life, and (4) lack of qualification and certification. This talk will present our research on overcoming these challenges to achieve predictable, consistent and reliable additive manufacturing through revealing the transient dynamics and fundamental mechanisms of laser-based metal additive manufacturing processes by in-situ high-speed synchrotron x-ray imaging and diffraction, as well as designing novel alloys and processing strategies based on the newly discovered mechanisms.

Progress in the direction of laser printing of sub-micrometer inorganic materials has mostly relied on inorganic/organic hybrid inks, which require a tedious post-printing high-temperature processing step, which is incompatible with the printing of multi-material structures. Here, we use a photothermal printing scheme to direct laser print sub-micrometer single crystalline ZnO without any post-processing steps beyond a simple rinse. This is accomplished using an intentionally chosen substrate and few milliwatts of continuous wave laser power. We further demonstrate the versatility of this simple print scheme by extending it to the photothermal laser printing of metals.

Ultrasound transducers are widely used in non-destructive testing, medical applications, and biology. Usually, ultrasound transducers are either capacitive micromachined ultrasonic transducers or commonly used piezoceramic-based systems. Capacitive micromachined ultrasonic transducers are traditionally fabricated in multi-step subtractive processes, e.g., wafer-bonding. In this presentation, we show that additive fabrication of capacitive micromachined ultrasonic transducers with different designs using 3D direct laser writing via multi-photon absorption is feasible. 3D direct laser writing is a 3D micro-printing technology that enables design freedoms that surpass the capabilities of traditional processes. Here, we present the fabrication of transducers with a center frequency between 500 kHz and 3.5 MHz – a frequency range often employed in air ultrasound in non-destructive testing. We benchmark thus fabricated ultrasound transducers based on oscillation amplitude, center frequency, bandwidth and transient response in air as well as under water. The results show that thus fabricated transducers are competitive with traditionally fabricated transducers.

Here, we demonstrate the laser-based 3D printing of freeform graphene aerogels by employing the concept of laser-based powder bed fusion using hemoglobin as the feedstock material, a common protein biowaste of the meat industry. Through the laser irradiation of freeze-dried powder, the low-value biowaste was directly converted into high-value turbostratic graphene, while simultaneously assembled into a 3D cellular network. By depositing another layer of powder and subsequently scanning the laser beam, the process can be easily scaled up to 3D print complex macrostructures. This work opens a new avenue to additively manufacture graphene aerogels with engineered architectures in multiple scales.

The production of via holes for PCBs is an ever-green topic. In the past CO2-Laser have been employed for drilling via holes with hole diameters down to about 25 µm. Due to miniaturization and higher interconnect densities, the via hole size has shrunk to about 10 µm for which short pulses UV-Laser sources are now used. The next generation PCBs require even smaller interconnects at significant higher densities: 5 µm hole diameter and tens of millions of holes per PCB substrate. Hole size, quality, position accuracy and production speed have become such demanding that the upcoming industrial-level, ultrashort pulses deep UV-Lasers enter the production field. In this presentation, the current generation UV-ns, UV-ps and the newly available DUV-ps Laser drilling processes for µVia holes will be compared.

Modern microelectronics applications require processing technologies that not only provide micron and sub-micron resolution, but also the highest throughput requirements with minimal defectivity and debris generation. Classical laser processing with infrared or visible wavelengths is challenged to limit the size of the affected regions to the sub-10µm range in non-metals, even when using ultrashort pulses. Lasers with wavelengths in the UV and DUV, however, offer linear absorption in many wide bandgap materials, resulting in a massive reduction in penetration depth and a more confined interaction volume. This opens the possibility of significantly improving both resolution and quality of laser processing, while maintaining high maximum throughput due to improved efficiency. This paper presents the results of investigations into several promising microelectronics applications, including sub-micron surface structuring, high-precision laser lift-off of GaN, high-speed grooving of silicon, and the generation of quantum defects in SiC.

High-quality OLED displays are a key feature for premium mobile phones. Pico- and femtosecond UV-lasers are used to cut the shape and hole with maximized active display area, and minimal HAZ. We will present our latest cutting results and strategies to increase quality and throughput using optimized process parameters for pulse energy, pulse repetition rate, wavelength, and optical setups. In our experiments we found the laser wavelength to be the most important parameter, followed by the pulse energy. In the UV (355 and 347 nm) we achieved excellent quality cuts with HAZ between 10 and 20 µm and cutting speed well above 100 mm/s, for both, ps and fs pulses. DUV ps-pulses (266 nm) improved the cutting quality tremendously, with HAZ below 10 µm and unprecedented edge quality. We will give an outlook how DUV cutting processes could be a breakthrough for display manufacturing.

In this paper, we will present results achieved with a high-power nanosecond UV laser source to process CFRP and PET materials. A parametric study will be presented, comparing the effects of various pulses from 2ns to 20ns and evaluating the interest of burst of pulses. We will show the interest of short nanosecond pulses for high quality and high speed processing compared to classical long nanosecond pulses.

Diamond’s strength comes from a tightly bound lattice of carbon. Nevertheless, laser writing with ultrashort laser pulses can be used for internal modification of the diamond lattice with 3D resolution and a myriad of applications. This talk will cover advances in laser written diamond devices, focusing on three recent developments: (i) fabrication of embedded nanocarbon networks for novel electrical structures; (ii) precision laser processing with spectral feedback for creation of single nitrogen vacancy and tin vacancy defects for quantum technology; (iii) rapid manufacture of subsurface serial numbers for diamond gem stone traceability initiatives.

This study examines two-photon polymerization (TPP) of SU-8 using GHz burst pulses of green wavelength fs laser by both experimental and simulation approaches. We show that by using the GHz burst pulses with an intra-pulse number of P = 10, the polymerization threshold energy of intra-pulses is 60% smaller than that of the conventional single-pulse mode and the TPP resolution is improved by 37%. The simulation results reveal that the fabrication of smaller polymerized structures with a lower threshold energy could be originated from the accumulation of thermal energy during irradiation of the subsequent intra-pulses in the GHz burst.

Graphene quantum dots (GQDs) are fluorescent nanoparticles with temperature-dependent fluorescence and have been studied for applications in anti-counterfeiting tags. We have reported that polydimethylsiloxane (PDMS) can be modified into a graphitic carbon and GQDs by femtosecond laser irradiation. Additionally, the formation of silicon carbide was observed. In this study, a semicylindrical conductive structure circled by GQDs was fabricated through a single-laser scanning of PDMS. Fluorescence microscopic images of the cross-sectional structure revealed the formation of a fluorescence structure around the conductive structure. The emission peak was observed at 400 nm (excitation at 360 nm) using a spectrometer, consistent with typical GQD fluorescence. Applying DC voltage to the structure induced Joule heating, leading to temperature-dependent changes in GQDs fluorescence intensity. The fluorescence intensity decreased as the temperature increased and recovered with cooling. Therefore, the fluorescence intensity can be modulated by applying voltage, which has potential applications in voltage-controlled optoelectronic devices.

MEMS devices, known for their broad applications, are typically fabricated using lithographic processes requiring masks. These methods pose barriers to rapid design and prototyping. We propose an innovative approach using laser-enabled direct-write technology for MEMS creation. Our method leverages ultrashort pulsed lasers for both subtractive and additive processes, allowing for micron and submicron feature creation with high repeatability. We developed protocols for fabricating intricate features such as holes. Incorporating gas processing during and between laser cycles improves feature quality by controlling material redeposition. This approach ensures cleaner edges and more defined structures. Our direct-write technology offers a rapid, flexible, and cost-effective alternative for MEMS fabrication, suitable for prototyping and production. This method accelerates development and opens new possibilities for MEMS applications, overcoming traditional lithographic constraints.

Cancer cells behavior in confined spaces is strongly related to cell-specific morphological deformations, which further influence the migration mechanism during the cancer metastasis processes. Two photon polymerization (TPP) was applied to tailor tissue-like scaffolds with narrow confined pores in polymeric materials. We have fabricated 3D scaffolds in SU8 photoresist by TPP, with pore sizes down to sub-micrometer dimensions. Such 3D platforms were further coated with collagen for testing the invasiveness potential of melanoma cancer cells in confined spaces. Quantitative analysis of cell adhesion and invasiveness within the scaffolds were performed by fluorescent microscopy of nuclei, cytoskeleton and focal adhesion points. We found that cellular affinity given by cell nuclei surrounding the scaffolds was two times higher when a collagen coating is was applied. The focal adhesion anchoring around the borders or inside the scaffolds was found much denser when collagen is was applied, but much stronger when collagen is was not used.

Optical and medical devices are frequently made of polymers and place high demands on precision, cleanliness, and reliability of the manufacturing processes used. Absorber-free laser transmission welding is well-suited for joining these devices: the energy input is contactless, no adhesives, additives, or absorbers are required, and the fiber lasers used enable precise weld seams. As the weld seam geometry is decisive for strength and tightness of the joint and thus crucial for the quality of the product, it is measured in-situ using optical coherence tomography (OCT) and subsequent semantic segmentation. Welding tests using polyamide 6 indicate that the seam width is measured with an accuracy of a few hundredths of a millimeter, showing excellent agreement with microscopic images of microtome sections.

Digital photocorrosion (DIP) of a semiconductor is a two-cycle process involving an irradiation and a dark phase. DIP of GaAs/AlGaAs has been investigated for detecting electrically charged biomolecules, such as bacteria and spores immobilized on the surface of such microstructures. Attractive biosensing results have been reported with DIP of a single GaAs-AlGaAs pair of nanolayers However, experiments concerning application of two, or a greater number of GaAs-AlGaAs nanolayers for repeated biosensing were less successful due to continuous accumulation of Ga- and Al-byproducts on the surface of biochips processing in phosphate buffered saline (PBS). To alleviate the problem of inefficient removal of GaAs/AlGaAs photocorrosion products in PBS, we examined a hybrid process consisting of replacing PBS with NH4OH-based etchant during dark phase of the DIP process. A computer-controlled protocol allowed sustainable DIP of a stack of GaAs-AlGaAs nanolayers observed in situ with non-vanishing photoluminescence intensity from GaAs. The proposed method has a great potential for the technology of regenerable biosensors designed for quasi-continuous environmental monitoring.

A modern integrated semiconductor product must include both light wave and microwave to outperform traditional ICs from complicated multiple-level micro sheets with low yields, high costs, and high heat, series resistance and capacitance. Microwave Lasing CMOS can be the building block of present and future processors and RF ASICs for commercial and defense products. It is desirable not to introduce extensive changes in existing architectures and circuit designs due to the fact that circuit designers and process engineering prefer a simplified approach in order not to disrupt production specifications and demands from customers. In this presentation we would like to outline design rules based on microwave and light wave CMOS computing that do not require major changes in existing circuit designs. In addition of the nano antennas and photonic waveguides, low voltage processing units transmit and receive microwave and light wave signals and reconstruct the high frequency signals in compliance with existing signal processing schemes, so no design changes are necessary in the input and output stages. It is essential to eliminate the hundreds of billions of micro metal wires in ULSIs.

Reliable industrial femtosecond lasers deliver output pulse duration from 200 fs to 1000 fs. External pulse compression allows shortening the pulse duration of these lasers well below 100 fs with an efficiency of typically 90%. Thus, for the first time, femtosecond lasers with <100 fs pulse duration become available for many applications. We study ablation of different glasses such as Schott , BK7, Fused Silica, Gorilla Glass, Zerodur and also Polyamide (Kapton) at 1030 nm central wavelength and 50 fs pulse duration. We compare those results with the ablation at 200 fs, 500 fs, and 1 ps pulse durations. Our results show that sub 100 fs and, in particular 100 fs pulses, show nearly no chipping when ablating the glass, lower roughness (40%), virtually no stress, or significantly less stress induced in the glass, depending on the type of glass and regime of ablation. Additionally, transparent ablation is possible in some types of glass (eg.Schott D263 and Gorilla glass). Also, we can form colorful structures on the surface of the glass which might be of interest for glass marking.

VCSELs are becoming more important for integration with silicon photonics, and emerging applications such as LiDARs, mobile and optical wireless tools, and advanced displays. Potentially, CMOS VCSELs may outperform traditional semiconductor diode based VCSELs, due to improved quantum efficiency from an internal positive feedback loop for CMOS lasers, operating with electric fields rather than thermal diffusions, better thermal stability, and reliability. In this report we present for the first time Discrete and Integrated Vertical NAND FLASH VCSELs. A Vertical NAND FLASH is a vertical NMOSFET with multiple gates as word lines and the drain regions at the top as bit lines. Multiple VCSELs, operating from NIR to UV, are in the NAND FLASH drain regions. Photon sensors are in the channel and well regions. VCSELs, NAND FLASH, and photon sensors are fabricated as one integral memory device. For CMOS Lasers, the CMOS channel and well regions are in the crystalline silicon. For Vertical NAND FLASH, the CMOS channel and well regions are made of polysilicon. With high temperature spike RTA, and separated multiple lasing regions, we have demonstrated high speed, high power VCSLE NAND FLASH.

A laser annealing technique to activate dopants is one of the essential processes to enhance the performance of advanced semiconductor device. In this study, experimental and numerical investigations of laser annealing process to activate phosphorus (P)-doped Si were conducted. More specifically, the laser annealing using dual-beam, a combination of continuous wave beam and pulsed beam, was explored to evaluate the feasibility of the dual-laser annealing in reducing thermal budget of the process and improving electrical properties of the P-doped Si. It was found that dual-beam process increased activation ratio of the P-doped Si while suppressing dopant diffusion.

This study analyzed the lower size limit of particle removal for laser-induced spray jet cleaning (LSJC) and steam laser cleaning (SLC). Although it has been long since these methods were developed, with the shift in primary target size towards the sub-10-nm range, reassessment of these two cleaning methods is necessary. Since previous studies have mostly been focused on relatively large particles, the processes have not been optimized for nanoscale particles. Consequently, this study aimed to optimize the cleaning processes through numerical simulation and experiment and to identify the smallest particle sizes that can be removed from a silicon surface. For SLC, the lower size limit, based on a 90 % particle removal efficiency (PRE) criterion, was 3 nm for gold particles but much larger for other particles. In LSJC, the lower size limit was 2 nm regardless of the particle type.

We report on the formation of homogeneous LIPSS by using the two-step ablation process with a square flattop beam of femtosecond (fs) laser pulses. The Gaussian beam from a Yb fs laser system was converted to a square flattop beam by passing through a refractive beam shaper and a square metal mask. This beam was split into two beams with a diffraction optical element and focused on a titanium surface. Firstly, the interference of these two beams formed an interference pattern with a period of 1.8 µm through ablation. Next, the single beam was irradiated onto the surface to form a homogeneous nanostructure with a period of 450 nm in 25 μm square area.

Graphene induced from polyimide (PI) through laser processing exhibits high conductivity and mechanical properties, making it promising for flexible, high-strength sensors, particularly pressure sensors. Previous studies using PDMS for packaging faced limitations due to its high cost and low internal cohesion. This study uses polyethylene (PE) for packaging LIG sensors, offering similar tensile strength and more economical properties. A grid pattern is laser-etched onto PI, followed by thermal bonding with PE to produce a flexible LIG film. The film undergoes UV light processing, converting PI to graphene while minimizing PE impact. Molecular dynamics simulations confirmed graphene formation and reduced inter-flake spacing under specific conditions, enhancing understanding of LIG production and applications in flexible electronics.

Ti-6Al-4V (Ti64) plate was additively fabricated with high energy efficiency by a blue diode laser induced powder bed fusion (L-PBF). In L-PBF, near-infrared (NIR) fiber laser is generally used, and it has been reported that the volumetric energy density (VED) of 60 J/mm³ is required for fabricating Ti64 with this laser. The absorption rate at a wavelength of 450 nm is 1.3 times higher than that of 1 µm. Therefore, we developed L-PBF device with a blue diode laser. Using the device, Ti64 part was formed with a porosity of 0.03% at a VED of 41 J/mm³.

Laser welding has attracted attention in various industries due to having high abilities such as deep penetration and automation. But spatter is a factor in the weld defects that cause material thinning and is difficult to remove once it adheres to the material surface. Therefore, it is required to develop a spatter-free process. In this study, we tried to expand the capillary aperture to slow down the velocity of the metal vapor by using the beam shaping technique because of spatter suppression. As the results, it was found that welding with a multi-spot laser has the effect of suppressing spatter.

Soft lithography is widely used for fabricating microfluidic devices due to its cost-effective and straightforward replication process. Critical to this process is the precise development of a master. Maskless laser beam lithography (LBL) is advantageous for creating polymeric masters and rapid prototyping complex devices, offering design freedom, integration of micro-optical/electrical elements, and cost-effectiveness. However, LBL can produce sub-optimal results with thick layers due to depth of focus limitations, affecting sidewall verticality. This work explores overcoming these limitations by testing SU-8 based negative resists at thicknesses over 0.3 mm, discussing sidewall verticality, aspect ratios up to 1:30, and spatial resolution limits. Potential applications and broader impacts of these micromachining capabilities are also examined.

In this study, we controlled the phase difference between six interfering beams using a SLM (Spatial Light Modulator) to manipulate interference patterns by a PC. The interference patterns were generated using an OPO (Optical Parametric Oscillator) at wavelengths ranging from 405 nm to 709.99 nm. When a phase difference in π/4 steps from 0 to 7π/4 was applied to one of the beams, the resulting patterns showed dots collapsing as the phase approached π, matching simulation results. Our findings confirm the effectiveness of using an SLM for interference pattern control, successfully establishing a system to control interference patterns of variable wavelength lasers.

This study explores the use of direct laser printing to fabricate VO2 microelectronics with integrated memristive and optoelectronic sensing capabilities. By developing a specialized VO2 ink, the research achieved precise controlling of material properties and device feature size. Remarkably, the process eliminates the need for traditional sintering or post-processing steps. Above metrics make this method highly flexible and explicit for the fabrication of smart electronics and sensors, holding promising applications in the next generation of digitally printed electronics.

We applied the 3D fabrication capability of ultrafast laser to fabricate 3D functional micro and nanodevices for chemical and biological applications. Applications of the fabricated devices include 3D micro and nanofluidic systems to elucidate mechanism of cancer cell metastasis and invasion in the human body, diagnostic microchips based on advanced digital nucleic acid amplification technique (d-NAAT), such as digital polymerase chain reaction (d-PCR), which consists of an array of more than 10,000 micro-through-holes on glass substrates, and 3D microfluidic surface enhanced Raman spectroscopy (SERS) chips enabling real-time sensing and attomolar level sensing of chemical and biological samples.

As a direct-write energy source, the laser has been a foundational tool in 3D material processing for nearly 50 years. 3D structures have been fabricated by both additive and subtractive approaches at spatial resolutions that now go well below the processing-laser wavelength. Complex shape structures have been fabricated by use of gas or liquid phase laser photochemistry or by the direct fusion of particles/powders. 3D structures can also be produced by stacking building blocks as by laser induced forward transfer or by optical tweezers. Finally, structures can be produced by altering the properties of the stock material itself to enhance removal by chemical means. In 3D growth of biological material, laser processing is used to build the scaffold on to which biological matter grows. Technologies that have enabled this wide array of organic and inorganic material processing capabilities include significant refinements in stage motion control and automation, developments that have produced lasers with stable power over a wide range of powers and wavelengths, shaping of the laser beam and temporal pulse permits local metering of the delivered energy, and modeling and simulation software that calculate the incident local electromagnetic field and tools that parse a 3D CAD model into a series of laser material processing steps. We will present an overview of laser 3D material processing/printing over the many years and discuss prospects of lasers and laser applications.

In consumer electronics and many other industries that widely employ laser micromachining technologies, there is an ever-growing trend towards better quality and higher process throughput. However, the complex nature of process dynamics, intertwined with the non-linear behaviors of laser-material interaction, makes rapid process development in laser micromachining applications challenging. At MKS|ESI, we have been actively developing state-of-the-art modeling capabilities for simulating industrial-level high-precision laser processing. This has become an indispensable tool for gaining process knowledge, minimizing the time and cost of process development, and helping to create new product solutions for our customers. In this talk, I will showcase simulation studies that offer useful insights into the fundamental physical mechanisms of laser-material interaction and guide the process development for pursuing new opportunities in laser micromachining applications. Specifically, these include laser via drilling in high-density-interconnect (HDI) and flex PCBs and rapid formation of through-glass-via (TGV) etc.

Scaling quantum processors using superconducting qubits is attractive given their high coherence and ease of fabrication. However, as-fabricated qubit frequency tolerances hover near ~2%, resulting in frequency crowding, thus limiting gate fidelity. We demonstrate LASIQ (laser annealing of stochastically impaired qubits) as a scalable post-fabrication frequency control technique, and its use on Eagle (127Q), Osprey (433Q), and Condor-scale (1121Q) devices. We discuss the limits of tuning precision and scaling implications for multi-qubit quantum processors.

Laser Induced Forward Transfer (LIFT) is a promising and innovative method for printing and metallizing electrodes using metallic inks and pastes for the PV industry. LIFT is a laser direct write technique that allows the selective transfer of a wide range of materials in different ranges of viscosity, from solid materials to pure Newtonian fluids In this work, we demonstrate the possibility of define a metallization process compatible with high efficiency solar cells using a two step laser-based process. First a commercial silver paste is printed using a Laser Induced Forward Transfer Process (LIFT) to define the metallization pattern onto the photovoltaic device using a ns-pulsed laser working at 532 nm. In the second step a CW green laser is used to sinter and functionalize the previously deposited contact. A comprehensive discussion of the influence of laser parameters (pulse energy, spot diameter, scanning speed, overlapping,…) on the morphology and electrical characteristics of the printed and sintered lines are included. As final proof of concept, we present results of printed metallization patterns onto silicon heterojunction silicon solar cells.

Advanced photovoltaic cells use thin layers of emerging materials like Cu2ZnSnSe4(CZTSe) instead of silicon. This study explores laser processing for the monolithic interconnection of CZTSe thin-film modules using a picosecond-pulsed laser working at three different wavelengths (355 nm, 532 nm, 1064 nm) and two irradiation methods (direct laser irradiation and irradiation through the glass substrate). Three processes (P1, P2, P3) target various layers to interconnect adjacent solar cells. This work aims to optimize the process parameters for precise material removal with minimal underlying layer damage.