Semiconductor Process Research Articles

Silicon rich nitride: a platform for controllable structural colors

Abstract High refractive index dielectric materials like silicon rich nitride (SRN) are critical for constructing advanced dielectric metasurfaces but are limited by transparency and complementary metal oxide semiconductor (CMOS) process compatibility. SRN’s refractive index can be adjusted by varying the silicon to nitride ratio, although this increases absorption, particularly in the blue spectrum. Dielectric metasurfaces, which utilize the material’s high dielectric constant and nano-resonator geometry, experience loss amplification due to resonance, affecting light reflection, light transmission, and quality factor. This study explores the impact of varying the silicon ratio on structural color applications in metasurfaces, using metrics such as gamut coverage, saturation, and reflection amplitude. We found that a higher SRN ratio enhances these metrics, making it ideal for producing vivid structural colors. Our results show that SRN can produce a color spectrum covering up to 166 % of the sRGB space and a resolution of 38,000 dots per inch. Fabricated samples vividly displayed a parrot, a flower, and a rainbow, illustrating SRN’s potential for high-resolution applications. We also show that SRN can provide a better CIE diagram coverage than other popular metasurfaces materials. These findings highlight the advantages of SRN for photonic devices, suggesting pathways for further material and application development.

Highly Enhanced Light Recycling in Quantum Dot Displays by Sidewall Reflectors

AbstractQuantum dot (QD) color conversion‐based displays have emerged as one of the most promising next‐generation devices due to their superior emission properties in terms of color expression. To date, however, existing QD color conversion layer (QD‐CCL) technologies have suffered from low luminance and power efficiency, mainly due to significant light absorption by the bank structure. Here, the color conversion efficiency of QD‐CCL has been significantly enhanced by fabricating a highly reflective metal layer on the side surface of the bank structure. Using a high‐aspect‐ratio silver reflector fabricated through a secondary sputtering lithographic technique involving argon ion bombardment, the fabricated QD‐CCL is combined with a blue organic light‐emitting diode (OLED) serving as a light source. As a result, light recycling from the reflector significantly enhances color conversion efficiency and luminance by up to 4.60‐fold and 4.29‐fold, respectively. Optical simulation reveals that higher pixel resolution provides greater reflection probabilities during extraction. This photomask‐free approach is not only simple but also highly compatible with existing semiconductor fabrication processes, making it a viable commercial alternative for all color‐converting structures that utilize light‐emitting materials with omnidirectional emission characteristics.

Study on the Destruction and Removal Efficiency (DRE) of Perfluorinated Compound Gases Used in Semiconductor and Display Processes in Korea: DRE and Uncertainty by Scrubber Type

In Republic of Korea, plasma scrubbers are a common technology employed in the semiconductor and display industries. However, there are numerous other types of scrubbers in use. The Intergovernmental Panel on Climate Change (IPCC) does not provide destruction and removal efficiencies (DREs) specific to individual scrubbers, only DREs specific to greenhouse gases, which makes it challenging to consider the specific effects of different types of scrubbers. The semiconductor and display industries in Korea represent a significant market share and are experiencing a steady increase in emissions, underscoring the need for research on GHG-reducing DREs to effectively manage these emissions. In this study, data on Tier 3 DREs developed based on measurements from companies subject to GHG management were collected. The findings indicated that C3F8 gas exhibited a comparable performance to the 2019 IPCC G/L (guideline) for plasma and combustion wet scrubbers, although it surpassed the 2006 IPCC G/L value. The catalytic scrubbers exhibited values that were comparable to the 2006 IPCC G/L, but lower than the 2019 IPCC G/L. The uncertainties were minimal for c-C4F8 gases, both in the absence of consideration of the scrubber type and when each scrubber type was taken into account. In contrast, the uncertainties associated with CF4 gases were relatively high, depending on the scrubber type. Although there are differences between the greenhouse gases in question, failing to take the type of scrubber into account could result in under- or overestimates of certain emissions. Therefore, it would be beneficial to develop coefficients that take this into account, particularly where information on scrubbers by gas type is available.

Real-time, specific, and label-free transistor-based sensing of organophosphates in liquid

Organophosphates (OP), commonly used in agriculture and as chemical warfare agents, pose significant environmental risks, necessitating real-time, low-cost OP detection methods. In particular, liquid-phase OP sensing with minimal sample volumes is crucial. While several methods allow rapid detection of low concentrations of OP vapors, they are effective only in the short term, while vapors are still being produced. Many OP compounds are semi-volatile, leading to the contamination of water, soil, and surfaces, posing a risk of secondary, long-term exposure. Detecting this contamination requires methods that can be directly applied to droplets of the affected medium. Currently, no method provides the desired combination of ultra-sensitivity, quantitative detection, rapid response, and low-cost for detecting OPs in liquid samples. This study aims to demonstrate quantitative, low-cost, real-time, specific, and label-free OP sensing in ultra-small samples using a transistor-based approach. The current work employs the 2-(4-Aminophenyl)-1,1,1,3,3,3-hexafluoro-2-propanol (aminophenyl-HFIP) functionalized meta-nano-channel field-effect chemical sensor (MNChem sensor) to monitor the organophosphate, diethyl cyanophosphonate (DCNP), in liquid samples. The silicon component of the MNChem is fabricated using a complementary metal-oxide semiconductor (CMOS) process, and the amine-based chemical functionalization of the sensing area is performed post-fabrication. The MNChem sensor provides electrostatic control over the source-drain current (IDS), allowing an optimized channel configuration that efficiently transduces localized OP recognition events into significant IDS variations. Sensing is performed using 0.5 μL buffer solution to simulate a miniature field-deployable sensor for on-site liquid analysis. We report the sensing of DCNP with a limit-of-detection of 100 fg/mL, a dynamic range of 9 orders of magnitude, and excellent linearity (≥0.97) and sensitivity. Control measurements confirm the specificity and reliability of the sensor's response, validating its applicability. This study introduces a novel method for OP detection in contaminated droplets using a low-cost disposable transistor technology.

Oxygen plasma-assisted magnetron sputtering deposition of non-stoichiometric Y2O3 films: Influence of oxygen vacancies on etching resistance

Yttrium oxide (Y2O3) films are widely used to protect equipment in plasma etching, a crucial technique in semiconductor processing, due to their exceptional resistance to plasma etching. Since oxygen vacancy affects the performance of Y2O3 and may impact physical etching resistance, the internal relationship necessitates further investigation. In this article, Y2O3 films with varying oxygen vacancy concentrations are prepared by reactive magnetron sputtering with the assistance of oxygen plasma. The formation and development of oxygen vacancies in cubic Y2O3 films and their impact on the physical etching resistance were investigated. The experiment results indicate that the accumulation of oxygen vacancies causes non-stoichiometry and the etching rate is significantly reduced. Combined with density-functional theory, it is revealed that oxygen vacancy distorts the lattice, which increases covalent YO bonding and the formation energy of atoms. Moreover, the vacancy line defects resulting from diffusion and aggregation of oxygen vacancies exert a similar influence on the adjacent yttrium and oxygen layers. The enhancement of physical etching resistance is attributed to the strengthened internal YO bonds led by increasing oxygen vacancy concentration in the cubic Y2O3 films without inducing phase transition. The discovery enriches the understanding of how plasma interacts with Y2O3, and the etching mechanism.

Novel Integrated Reference-Counter Electrode for Electrochemical Measurements of HOMO and LUMO Levels in Small-Molecule Thin-Film Semiconductors for OLEDs

Organic light-emitting diodes (OLEDs) are a prominent display technology, yet the accurate characterization of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels in their constituent materials remains challenging. This study introduces a novel integrated reference-counter electrode (IRCE) assembly, leveraging a gel polymer electrolyte with an embedded silver quasi-reference electrode, facilitating the electrochemical measurement of HOMO and LUMO levels in small molecular thin-film semiconductors. Calibration of the IRCE against ferrocene enables the establishment of an absolute energy scale. Comparative stability tests against a standard Ag/AgNO3 reference electrode confirm the IRCE's reliability. Electrochemical characterization using cyclic voltammetry was performed on prototypical OLED materials, including NPB, TCTA, PO-T2T neat films, and an NPB:PO-T2T exciplex film. While NPB and PO-T2T exhibited stable voltammograms, TCTA showed signs of electropolymerization. Additionally, the HOMO level of the NPB:PO-T2T exciplex was slightly shifted compared to that of NPB, suggesting interactions within the exciplex. The results demonstrated the IRCE's capability to accurately determine frontier energy levels in thin films, paving the way for better device modeling and a better understanding of underlying electronic processes in organic semiconductors.

Dielectrophoretic capture of Escherichia coli and boar sperms using ULSI-fabricated three-dimensional protruding TiN nano-electrode arrays.

In recent years, dielectrophoresis has become widely recognized as a highly suitable method for creating good tools for particle separation, with significant successes achieved in a variety of areas. Expanding upon this, we adopted a semiconductor CMOS process, instead of a MEMS process, which allowed for the following: 1) wire insulation to mitigate Joule heat and prevent thermal fluctuation interference with the dielectrophoretic force; 2) isolation of harmful materials from biological samples, making the chip biocompatible; and, 3) the ability to employ nano-electrodes capable of generating a stronger electric field than conventional electrodes, thus allowing chip capture at lower voltages. Additionally, our chip is scalable, enabling multiplied throughput based on sample processing requirements. These features make our chip more widely applicable and suitable for capturing bacteria and sperm. In this study, we focused on optimizing the parameters of dielectrophoresis and employed 3-D protruding TiN nano-electrode arrays to facilitate the capture of Escherichia coli and boar sperms. The experimental data demonstrates that the capture efficiency of this chip for E. coli was approximately 79.25% ± 2.66%, and the highest capture efficiency for sperms was approximately 39.2% ± 3.9%.

Development of smart molecularly imprinted tetrahedral amorphous carbon thin films for in vitro dopamine sensing

This study investigates how varying the thickness of tetrahedral amorphous carbon (ta-C) thin films and incorporating a titanium adhesion layer influences the structural and electrochemical properties of molecularly imprinted ta-C thin film-based sensing platforms, aiming to develop a molecularly imprinted ta-C electrochemical sensor for dopamine (DA) detection with physiologically relevant sensitivity. This electrochemical sensing platform was designed by integrating ta-C with molecularly imprinted polymers (MIPs). The process involved depositing a ta-C thin film onto boron-doped p-type silicon wafers through a filtered cathodic vacuum arc (FCVA) system. Subsequently, the ta-C sensing platforms were electrochemically coated with the MIP layer (DA-imprinted polypyrrole). We evaluated three configurations: (i) a 15 nm ta-C layer, (ii) a 7 nm ta-C layer with a 20 nm titanium adhesion layer, and (iii) a 15 nm ta-C layer with a 20 nm titanium adhesion layer. Comprehensive structural and electrochemical characterization was performed to understand how these modifications affect sensor performance. The optimized MIP/ta-C sensor demonstrated a sensitivity of 0.16 μA μM−1 cm−2 and a limit of detection (LOD) of 48.6 nM, suitable for detecting DA at physiological levels. Leveraging the synergistic effects of ta-C coatings and molecular imprinting, as well as its compatibility with common complementary metal–oxide–semiconductor (CMOS) processes underlines its potential for integration into microanalytical systems, paving the way for miniaturized and high-throughput sensing platforms.

Impact of Deposition Temperature on Structural and Electrical Properties of Sputtered AlN/ Si (111) for CMOS compatible MEMS

Aluminium nitride (AlN) thin films are grown by reactive sputtering on Silicon (Si) with (111) orientation at low temperature (< 450 °C) for piezoelectric-based micro-electromechanical systems (MEMS). The grown AlN thin films were polycrystalline wurtzite hexagonal structure with a high texture coefficient for the (002) plane of orientation. The leakage current density by the current-voltage (I-V) measurement was found to be as low as 1.6 ×10-6Acm−2 in the grown films. The trapped charges are crucial in controlling these electrical characteristics, and low interface trap density (6.72 ×1010cm−2 eV) was observed for the sputtered AlN grown at a substrate temperature of 300 °C. This study on the structural and electrical properties of AlN/Si (111) at low substrate temperature is compatible with the complementary metal oxide semiconductor (CMOS) process for constructing piezoelectric-based MEMS devices for various applications.

Fabrication and evaluation of a CMOS-based energy harvesting chip integrating photovoltaic and thermoelectric energy harvesters

This study explores the development of an energy harvesting chip (EHC) using a complementary metal oxide semiconductor (CMOS) process, addressing the need for efficient micro-scale energy harvesters in modern electronics. The EHC integrates a thermoelectric energy harvester (TEH) and a photovoltaic energy harvester (PEH) to maximize energy conversion efficiency. A key challenge in TEH design is enhancing power output, which is addressed by suspending the cold ends of 41 thermocouples within the TEH structure through post-processing. Experimental methods were employed to assess the performance of the TEH, revealing an output voltage of 21.4 mV and a maximum output power of 9.32 nW under a 3 K temperature difference. The TEH demonstrated a voltage factor of 8.9 mV/(mm2·K) and a power factor of 1.3 nW/(mm2·K2). The PEH was designed with novel patterned p-n junctions, integrating lightly doped n-type regions with interdigitated p-type doping to increase junction density, resulting in high conversion efficiency. The experimental results confirm the effectiveness of the EHC design, showcasing its potential in energy harvesting applications.

반도체 장비 교육을 위한 PLC기반 PID제어 가상 시스템 개발 및 구현에 관한 연구

IIn line with the government’s recent semiconductor talent training policy, vocational high schools and universities are receiving substantial funding for facility and equipment construction. Building semiconductor cleanroom facilities and processing equipment is very costly, while the limited lab space makes providing semiconductor education difficult. Therefore, an alternative education method which solves these issues is needed. To make PID control learning of semiconductor equipment more accessible in terms of cost, space, and difficulty, this study implemented a virtual system in a virtual simulation space, and confirmed the educational effectiveness through a comparative analysis of the real situation and virtual simulation.

Tomography of entangling two-qubit logic operations in exchange-coupled donor electron spin qubits

Scalable quantum processors require high-fidelity universal quantum logic operations in a manufacturable physical platform. Donors in silicon provide atomic size, excellent quantum coherence and compatibility with standard semiconductor processing, but no entanglement between donor-bound electron spins has been demonstrated to date. Here we present the experimental demonstration and tomography of universal one- and two-qubit gates in a system of two weakly exchange-coupled electrons, bound to single phosphorus donors introduced in silicon by ion implantation. We observe that the exchange interaction has no effect on the qubit coherence. We quantify the fidelity of the quantum operations using gate set tomography (GST), and we use the universal gate set to create entangled Bell states of the electrons spins, with fidelity 91.3 ± 3.0%, and concurrence 0.87 ± 0.05. These results form the necessary basis for scaling up donor-based quantum computers.

Spatially-resolved spectroscopic investigation of the inhomogeneous magnetic field effects on a low-pressure capacitively-coupled nitrogen plasma

Although magnetized plasmas have been frequently used to enhance the process rate or improve the film quality via the control of ion flux as well as energy and plasma density in semiconductor processes, the inhomogeneous magnetic field—which leads to plasma non-uniformity—remains as a problem to be solved. To address this problem, it is essential to conduct a comprehensive assessment of the magnetic effect throughout the entire discharge. Therefore, in the present study, we investigated the magnetic field effects (B < 100 G) on a capacitively-coupled nitrogen plasma based on spectroscopic analyses. The spatially-resolved emission spectra were measured along the radial direction at various vertical positions under the pressures of 10 mTorr and 250 mTorr both with and without magnetic field. By analyzing emission spectra such as N2 FPS, N2 SPS, N2+ FNS, and N I, we were able to obtain the radial distributions of reactive species density, vibrational temperature, and excitation temperature. In low-pressure plasma, with the application of a magnetic field, maximum increases in vibrational temperature and excitation temperature of 462 K and 491 K, respectively, were observed within the bulk region beneath the magnet. This magnetic effect resulted in a significant increase in reactive species density along the radial direction. It was also found that the local enhancement of ion density by magnetic field was strongly related to the increase in excitation temperature and the density of the N2+(B) state. From this result, it is suggested that introducing an asymmetric magnetic field could modulate the spatial distributions of the physical and chemical properties of the plasma.

Deuterium Isotopic Effect on Nanometer-Sized Narrow Spaces Formed by Silicon Walls

Unveiling a solid–liquid reaction in a nanoconfined region is required to control the wet processes of advanced semiconductors whose sizes can reach several nanometers. In this study, using deuterium isotope effects, we investigated the influence of reactant consumption by confining walls on the etching rate of nanoconfined spaces. By analyzing the states of the silicon surface and the etching rate of SiO2 film confined by the silicon walls in hydrofluoric acid diluted with H2O or D2O, we observed that deuterium can suppress the reaction on the wall surface and that deuterium fluoride increases the etching rate in nanoconfined regions. Therefore, we conclude that the wet-etching behavior can be determined by the reactant consumption on the confining walls.

Ultrasensitive integrated circuit sensors based on high-order non-Hermitian topological physics.

High-precision sensors are of fundamental importance in modern society and technology. Although numerous sensors have been developed, obtaining sensors with higher levels of sensitivity and stronger robustness has always been expected. Here, we propose theoretically and demonstrate experimentally an alternative class of sensors with superior performances based on exotic properties of high-order non-Hermitian topological physics. The frequency shift induced by perturbations for these sensors can show an exponential growth with respect to the size of the device, which can grow well beyond the limitations of conventional sensors. The fully integrated circuit chips have been designed and fabricated in a standard 65-nanometer complementary metal-oxide semiconductor process technology. Not only has the sensitivity of systems less than 10-3 femtofarad been experimentally verified, but these systems are also robust against disorders. Our proposed ultrasensitive integrated circuit sensors can have a wide range of applications in various fields and show an exciting prospect for next-generation sensing technologies.

Imaging of Volatile Organic Compounds Using a Single Nanowire-Based Electronic Nose for Future Biomedical Applications.

This study introduces an array of semiconductor oxide single nanowires fabricated using advanced semiconductor processing techniques, including electron beam lithography and thin-film deposition, which is well-suited for large-scale nanowire integration. A four-channel nanowire array consisting of tin oxide (SnO2), indium oxide (In2O3), ferric oxide (Fe3O4), and titanium oxide (TiO2) was developed. As a proof of concept, we converted the response curves of the sensor array to heat maps, enabling comprehensive feature representation. The fabricated electronic nose (E-nose) was utilized to detect three types of volatile organic compounds (VOCs), with the results visualized in a heat map format. Additionally, the performance of each individual sensor was quantitatively studied, highlighting the array's potential for enhanced gas detection and analysis. To further illustrate the interaction between gas molecules and the nanowires, we visualized the gas response results by mapping the sensor's signal changes. These visualizations provide a clear representation of how different gas molecules interact with specific nanowires. For example, the heat maps reveal distinct response patterns for each type of VOC, allowing for the identification and differentiation of gases based on their unique signatures. This visualization technique not only enhances the understanding of gas-nanowire interactions but also demonstrates the effectiveness of the E-nose in distinguishing between various VOCs. The SnO2 nanowire gas sensor showed enhanced gas response compared to other materials. The SnO2 and TiO2 gas sensors showed enhanced response (62 and 56 s) and recovery times (100 and 37 s).

Study on the performance of InGaN-based micro-LED by plasma etching combined with ion implantation process

This study utilized blue-light epitaxial wafers and employed semiconductor processes such as maskless laser writing, dry etching, wet etching, passivation layer deposition, electron beam evaporation, and ion implantation to fabricate micro-light emitting diode (μLED) arrays with different pixel sizes but the same emitting area (900 μm²). The μLED arrays with single pixel sizes of 5 μm, 10 μm, and 15 μm were fabricated, with array numbers of 6×6, 3×3, and 2×2, respectively. This study proposes etching the material in the channel region while retaining a certain width for implantation, known as the sidewall ion implantation process, aiming to achieve better insulation characteristics by using ion implantation technology to insulate the sidewall regions. It involves ion bombardment of the defect areas generated after plasma etching and the use of a passivation layer for protection. The isolation characteristics of μLED arrays processed by sidewall implantation exhibited better electrical isolation than those of μLED arrays processed only by plasma. The light output power, external quantum efficiency, and wall-plug efficiency were all superior for the sidewall implantation process when the device was miniaturized to 5 μm. Overall, the sidewall implantation process combined with plasma dry etching effectively improved the light output characteristics, with the enhancement ratio increasing as the device was miniaturized.

Numerical simulation of electrically-pumped overgrown III-V microwire lasers on silicon

Electrically-pumped III-V lasers on Si by aspect ratio trapping (ART) techniques have been a promising candidate for Si-based light sources. Although the lasers based on the ART approach enable large-scale integration and are compatible with complementary metal-oxide semiconductor processes, the sub-micron size laser structure suffers from severe metal absorption loss and heat accumulation. In this paper, we propose a novel Si-based III-V multi-quantum well laser by ART methods. The overgrowth of III-V microwires is adopted, with additional {110} quantum wells (QWs) generated during epitaxy. Through numerical simulation, the mode loss of the overgrowth structure is reduced from 3.59 dB/cm to 0.96 dB/cm, the threshold current is decreased by 42.5% and the output power is increased by 91.7% under pulsed conditions. Due to the growth of QWs on {110} planes, the injection efficiency of the device increases, leading to an improvement of performance. The effects of temperature and cavity length on the lasing characteristics of the device under continuous wave (CW) conditions are also analyzed that the proposed structure can realize CW lasing at room temperature. Moreover, the device deterioration caused by growth defects is discussed, which can be improved by high reflection coating. The suggested Si-based overgrowth III-V microwire laser has great potential to integrate high-density electrically-pumped light sources for silicon photonics.

Solution-processed NO2 gas sensor based on poly(3-hexylthiophene)-doped PbS quantum dots operable at room temperature

The global industrial development and increase in the number of transportation vehicles, such as automobiles and ships, have led to a steady increase in the issues related to greenhouse gas emissions. NO2 is a greenhouse gas emitted in large quantities from automobiles and factories, and its emission is unavoidable in the modern world. Therefore, a sensor capable of precise detection of NO2 is required. The most commonly reported types of NO2 sensors are those based on metal oxides. However, their operation at room temperature is impossible owing to their high-temperature operating characteristics, and therefore, a heater must be designed inside or installed outside the sensor for heating. Meanwhile, NO2 sensors based on PbS quantum dots (QDs) are advantageous as they can operate at room temperature and can be easily manufactured through a solution process rather than a complicated semiconductor process. Herein, a NO2 sensor was fabricated by doping PbS QDs with poly(3-hexylthiophene) (P3HT). The as-developed sensor exhibited high responsivity to 100–0.4-ppm NO2 gas with a resolution of 200 ppb owing to the stability of the thin film and high hole mobility of P3HT.

Design and application of D‐band bandpass filter based on 0.18 μm complementary metal oxide semiconductor process

AbstractThis paper designs a bandpass filter for D‐band and 0.18 μm complementary metal oxide semiconductor (CMOS) process. The bandpass filter is composed of an inverted L‐shaped coupling microstrip line and a cross‐coupled resonator, and is coupled to produce two controlled transmission zeros. A defected ground structure is used to make a good impedance match. The designed filter has a 3 dB impedance bandwidth of 52 GHz (149–201 GHz) with a center frequency of 175 GHz and an insertion loss of 3.23 dB. The design of this paper is a CMOS 0.18 μm process capable of applying the D‐band bandpass filter with the advantages of lower insertion loss, broadband, and compact size.