Plasma Etching Technology Research Articles

Fabrication of the hexagonal Si nanorod arrays using the template of polystyrene nanospheres in monolayer dispersion

Silicon etching is an essential fabrication step in micro-/nanoelectromechanical systems. In this article, the inductive coupled plasma etching technology using monolayer polystyrene nanospheres as the template provides a feasible top-down dry etching method in silicon substrates. The size of the polystyrene nanosphere templates coated on the silicon substrate was adjusted using O2 plasma etching, and the subsequent inductive coupled plasma etching process was applied to produce the silicon nanorods by alternatively employing etching gas SF6 and protective gas C4F8. The O2 plasma etching time on the template and the SF6/C4F8 flow rate for etching Si substrate were optimized in order to obtain the silicon nanorod structures in the hexagonal morphologies with good verticality, uniformity, and periodicity.

High extinction ratio polarization beam splitter with multimode interference coupler on SOI

A high extinction ratio polarization beam splitter based on multimode interference coupler has been obtained on silicon-on-insulator. The multimode interference coupler is designed by using quasi-state imaging theory, and fabricated with E-beam lithography and induced coupled plasma etching technology. The device has footprint of 8.16μm×1034μm. The measured extinction ratios remain 45dB for TE mode and 23dB for TM mode at wavelength of 1.55μm. The extinction ratio of more than 20dB for TE mode and 15dB for TM mode is observed covering the whole C-band.

Multireflection modal method for wideband fused-silica transmission gratings

A multireflection modal method is proposed to give a clear physical picture for explanation of the diffraction process that takes place in a wideband fused-silica transmission grating. Using rigorous coupled-wave analysis, the optimized grating exhibits diffraction efficiency greater than 93.9% for TE polarization over a bandwidth of 126 nm (from 735 to 861 nm). The designed wideband fused-silica transmission grating is fabricated using holographic interference recording and inductively coupled plasma etching technology. Experimental results are in agreement with the theoretical values.

Design, Simulation, and Fabrication of Microneedles and a Blood Filter for Use in a Hemofiltration System

This paper deals with the design of a new hemofiltration system that consists of a blood transport device, a blood filtration device, a drug delivery device, flow sensors, blood pressure sensors, and the required control electronic circuits. The simulation and fabrication of microneedles and hemofilter have been performed. Silicon microneedles with length ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</i> ) = 200 μm, internal diameter (Di) = 60 μ m, and outer diameter (Do) = 150 μm have been successfully fabricated using inductive coupled plasma (ICP) etching technology for drug delivery. An aluminum (Al)-based hemofilter with hexagonal pores has been fabricated for blood filtration. Strength modeling and microfluidic analyses of the hemofilter have been conducted in finite element software to envisage structural properties and to model blood flow through the hexagonal pores. Simulation results show that a flow rate of 488.43 μL/min has been obtained at a driving pressure of 250 kPa through a hemofilter with hexagonal pores. Transient multifield analysis of the blood transport device (double lumen, side open, reservoir-based microneedles integrated with a piezoelectric actuator) has been conducted using the finite element method. The effects of actuator thickness, applied frequency and voltage on fluid flow rate have been investigated using the blood transport device. A maximum flow rate of 475 μL/min has been observed through 25 microneedles at an applied voltage of 125 V with a frequency of 250 Hz.

Wet Etching of Aluminum Periodic Patterns in Micrometer-Scale

In the process of deep etching of silicon, the metal film or the oxide film served as silicon protective layer needed to be etched before using plasma etching technology. In order to solve the etch rates variance of different aperture sizes and different pitchs periodic patterns, by controlling the water bath temperature and etching time, the etch rates of different aperture sizes and different pitchs periodic patterns at 50 degree centigrade had been developed. Also we contrasted the etching results at different bath temperatures and got the controllable and suitable wet etching bath temperature 50 degree centigrade. At last, the paper further explores the effects of feature size and the wet etching bath temperature on etch rate.

Simulation and fabrication of blood filtration system for patients with kidney diseases

Here the authors present the new design of blood filtration system for patients with kidney diseases. The proposed system consists of electronic module, drug delivery part, blood extraction and blood insertion part, blood filtration part, flow sensors and blood pressure sensor. Electronic module provides necessary functionalities and control to other components of system. Using inductively coupled plasma etching technology hollow silicon microneedles have been developed for drug delivery part. Nano porous aluminium membrane has been fabricated for blood filtration part. Ultra-sharp tip polymeric dual radii microneedles have been proposed for blood extraction and insertion part. Using ANSYS, strength modelling, microfluidic static and multifield analyses have been conducted. Water, ethanol and blood have been used as working fluid in microfluidic analysis to foresee the flow rate and viscosity effect through microneedles. Fluidic analysis shows that the proposed design is suitable for blood transport because two different lumens radii in microneedles are useful to avoid the clogging effect because of pressure difference in the lumen regions.

Optimization of Fabrication Process for MEMS Based Microneedles Using ICP Etching Technology

In this paper, optimization of fabrication process for microneedles has been presented. Using inductively coupled plasma (ICP) etching technology, fabrication of out-of-plane hollow silicon microneedles for blood extraction has been carried out. Sharp tip microneedles with length 1100 µm were designed for fabrication. The fabrication of microneedles was not successful because the lumen section was fabricated first and then hole was created for fluid flow. Previously, using same fabrication method successful fabrication of microneedles was done for drug delivery with length 200 µm. This fabrication method is not suitable for long structure. Thus, the alternative microneedle fabrication steps using ICP etching have been developed and presented in this paper. These steps can be more optimized and suitable for sharp tip, long and hollow structure.

Tunable filters based on an SOI nano-wire waveguide micro ring resonator

Micro ring resonator (MRR) filters based on a silicon on insulator (SOI) nanowire waveguide are fabricated by electron beam photolithography (EBL) and inductive coupled plasma (ICP) etching technology. The cross-section size of the strip waveguides is 450 × 220 nm2, and the bending radius of the micro ring is around 5 μm. The test results from the tunable filter based on a single ring show that the free spectral range (FSR) is 16.8 nm and the extinction ratio (ER) around the wavelength 1550 nm is 18.1 dB. After thermal tuning, the filter's tuning bandwidth reaches 4.8 nm with a tuning efficiency of 0.12 nm/°C Meanwhile, we fabricated and studied multi-channel filters based on a single ring and a double ring. After measurement, we drew the following conclusions: during the signal transmission of multi-channel filters, crosstalk exists mainly among different transmission channels and are fairly distinct when there are signals input to add ports.

A Biaxial Capacitive Microaccelerometer with a Single Proof-Mass

This work focuses on the development of a biaxial fully differential capacitive microaccelerometer with a single proof-mass. Its design, optimization and fabrication are discussed in detail. Structure and geometric parameters are optimized by multidisciplinary design optimization, enabling ±1g operating range, 1182Hz resonant frequency, 97 fF/g sensitivity, 4.1mg resolution and 0.68 damping ratio. Silicon-on-glass (SOG) bulk micromachining and inductively coupled plasma (ICP) etching technologies are adopted to fabricate this accelerometer.

Highly Efficient Metal-Free Growth of Nitrogen-Doped Single-Walled Carbon Nanotubes on Plasma-Etched Substrates for Oxygen Reduction

We have for the first time developed a simple plasma-etching technology to effectively generate metal-free particle catalysts for efficient metal-free growth of undoped and/or nitrogen-doped single-walled carbon nanotubes (CNTs). Compared with undoped CNTs, the newly produced metal-free nitrogen-containing CNTs were demonstrated to show relatively good electrocatalytic activity and long-term stability toward oxygen reduction reaction (ORR) in an acidic medium. Owing to the highly generic nature of the plasma etching technique, the methodology developed in this study can be applied to many other substrates for efficient growth of metal-free CNTs for various applications, ranging from energy related to electronic and to biomedical systems.

Design, Fabrication and Analysis of Silicon Hollow Microneedles for Transdermal Drug Delivery System for Treatment of Hemodynamic Dysfunctions

In this paper, we present design, fabrication and coupled multifield analysis of hollow out-of-plane silicon microneedles with piezoelectrically actuated microfluidic device for transdermal drug delivery (TDD) system for treatment of cardiovascular or hemodynamic disorders such as hypertension. The mask layout design and fabrication process of silicon microneedles and reservoir involving deep reactive ion etching (DRIE) is first presented. This is followed by actual fabrication of silicon hollow microneedles by a series of combined isotropic and anisotropic etching processes using inductively coupled plasma (ICP) etching technology. Then coupled multifield analysis of a MEMS based piezoelectrically actuated device with integrated silicon microneedles is presented. The coupledfield analysis of hollow silicon microneedle array integrated with piezoelectric micropump has involved structural and fluid field couplings in a sequential structural-fluid analysis on a three-dimensional model of the microfluidic device. The effect of voltage and frequency on silicon membrane deflection and flow rate through the microneedle is investigated in the coupled field analysis using multiple code coupling method. The results of the present study provide valuable benchmark and prediction data to fabricate optimized designs of the silicon hollow microneedle based microfluidic devices for transdermal drug delivery applications.

Etching blazed grating into quartz substrate with selectivity 1:1 against photoresist by inductively coupled plasma technology

Inductively coupled plasma (ICP) etching technology is becoming widely used in the fabrication of micro-optical elements. Because of its advantages such as relatively high etching rate and anisotropic etching, ICP technology is receiving more attention. Selectivity 1:1 of the substrate against photoresist is very convenient, because we can easily get the same structures which were designed on the photoresist. Through extensive experiments we have achieved an optimized etching condition under which the transfer process generates fairly smooth etched structures with selectivity 1:1. The first order diffraction efficiency of the etched blazed gratings is 83.5% which is a little bit lower than the theoretical efficiency 88.9%. The diffraction of etched blazed gratings matches the theoretical results well.

Improved light extraction of GaN-based light-emitting diodes with surface-textured indium tin oxide electrodes by nickel nanoparticle mask dry-etching

GaN-based light-emitting diodes (LEDs) with surface-textured indium tin oxide (ITO) as a transparent current spreading layer were fabricated. The ITO surface was textured by inductively coupled plasma (ICP) etching technology using a monolayer of nickel (Ni) nanoparticles as the etching mask. The luminance intensity of ITO surface-textured GaN-based LEDs was enhanced by about 34% compared to that of conventional LED without textured ITO layer. In addition, the fabricated ITO surface-textured GaN-based LEDs would present a quite good performance in electrical characteristics. The results indicate that the scattering of photons emitted in the active layer was greatly enhanced via the textured ITO surface, and the ITO surface-textured technique could have a potential application in improving photoelectric characteristics for manufacturing GaN-based LEDs of higher brightness.

Etching characteristics of organic low-k films interpreted by internal parameters employing a combinatorial plasma process in an inductively coupled H2/N2 plasma

The development of plasma etching technology is being held back due to the use of trial and error methods when scaling down and high integration. Such a continuous development could result in enormous losses in term of cost and time. It is impossible to overcome without a different approach. In this study, we have tried to accumulate a large amount of data on internal parameters and based on database, the etching characteristics could be interpreted with a high reproducibility. In order to realized faster data acquisitions, we developed a combinatorial plasma process (CPP) for obtaining a large amount of data in a single trial from spatially inhomogeneous plasma distribution regarding etching of organic low-k films in H2/N2 plasmas. In addition, synergetic effects of other internal parameters such as vacuum ultraviolet radiation and radicals without ion bombardment were clarified. Finally, the high performance of CPP for faster data acquisitions was shown and the etching characteristics in terms of internal parameters such as ion fluxes and the H/(H+N) radical flux ratio were demonstrated.

Deep-etched sinusoidal polarizing beam splitter grating

A sinusoidal-shaped fused-silica grating as a highly efficient polarizing beam splitter (PBS) is investigated based on the simplified modal method. The grating structure depends mainly on the ratio of groove depth to grating period and the ratio of incident wavelength to grating period. These ratios can be used as a guideline for the grating design at different wavelengths. A sinusoidal-groove PBS grating is designed at a wavelength of 1310 nm under Littrow mounting, and the transmitted TM and TE polarized waves are mainly diffracted into the zeroth order and the -1st order, respectively. The grating profile is optimized by using rigorous coupled-wave analysis. The designed PBS grating is highly efficient (>95.98%) over the O-band wavelength range (1260-1360 nm) for both TE and TM polarizations. The sinusoidal grating can exhibit higher diffraction efficiency, larger extinction ratio, and less reflection loss than the rectangular-groove PBS grating. By applying wet etching technology on the rectangular grating, which was manufactured by holographic recording and inductively coupled plasma etching technology, the sinusoidal grating can be approximately fabricated. Experimental results are in agreement with theoretical values.

Impact of plasma etching on fabrication technology of liquid crystal polymer printed circuit board

Liquid crystal polymer (LCP) has attracted great attention as a potential candidate for high performance micro-wave substrate material in high frequency printed circuit boards (PCB). This is attributed to its low loss behaviour, excellent thermal stability, and outstanding chemical resistance. The use of LCP in PCB, however, is hindered by its extreme chemical inertness, causing fabrication challenges in desmearing and metallization processes. To overcome the challenges, plasma etching is suggested for its capability of smear removal, adhesion improvement and surface activation of PCB material. However, previous experimental and theoretical studies of the effects of plasma etching on LCP PCB at different treatment conditions are lacking. This paper thus evaluates recent developments on plasma etching technologies, involving the plasma etching investigation under different process conditions for manufacturing LCP PCB. Distinct process approaches are developed and proposed based on the illustrations of the experimental outcomes. Finally, examples are shown to demonstrate the effectiveness of the proposed plasma etching approach for controlling the fabrication of LCP PCB.

Mechanical characterization of thermal SiO2 micro-beams through tensile testing

A micro-tensile testing system has been developed to measure mechanical properties of a thermal SiO2 thin film. Through the stiffness coefficient calibration of the tensile system in situ, the deformation of the gage section is obtained using a two-serial spring model. A simple gripping method with rapid alignment is presented to improve alignment precision and repeatability of the measurement. Two kinds of specimens, including traditional ones and those with suspended spring beams, are fabricated using inductively coupled plasma (ICP) etching technology. The finished free-standing thermal SiO2 beams are buckled because of the compressive residual stress. The residual elongation of the beams could be obtained from the original load–displacement curves of the SiO2 beams. Thus the compressive residual stress, Young's modulus and the fracture strength of the thermal SiO2 beams were achieved simultaneously from the tensile testing. The measured values of Young's modulus are 64.6 ± 3 GPa for traditional SiO2 film specimens and 65.5 ± 2.8 GPa for those with suspended spring beams. The measured residual stress is 354 ± 26 MPa and the fracture strength is 426 ± 63 MPa. The measured modulus and residual stress are reasonably coherent with other reports.

Analysis of adopting an integrated decision making trial and evaluation laboratory on a technology acceptance model

The aim of study is to integrate decision making trial and evaluation laboratory (DEMATEL) into the theoretical extension of technology acceptance model (TAM2) to evaluate users’ behavioral intention to use while introducing a new etching plasma technology. The study used a case of the Taiwan plasma etching manufacturing industry as the example, adopted DEMATEL to calculate the causal relationship and interaction level between the TAM2 variables, and at the same time, use DEMATEL to find the core variables of TAM2, provide the managers the important key for management or improvement while promoting a new technology to resolve the complicated problems in practical experience. The study found that adopting DEMATEL in the TAM2 method, to find perceived ease of use, subjective norm and experience, is the key impact factors for the case study to decide the plasma etching technology acceptance model.

Synchronous Pulse Plasma Operation upon Source and Bias Radio Frequencys for Inductively Coupled Plasma for Highly Reliable Gate Etching Technology

Synchronous pulse operation upon both source and bias RFs for inductively coupled plasma (ICP) etching system, having both dynamic matching networks and RF frequency-sweeping to ensure the lowest RF reflected power, is introduced for the first time. A superior performance of synchronous pulse operation to conventional continuous wave (cw) as well as source pulse operations is confirmed through plasma diagnostics by using Langmuir probe, plasma simulation by using hybrid plasma equipment model (HPEM) and etching performance. Significant reduction of RF power reflection during pulse operation as well as improvement of 35 nm gate critical dimension (CD) uniformity for sub-50 nm dynamic random access memory (DRAM) are achieved by adapting synchronous pulse plasma etching technology. It is definitely expected that synchronous pulse plasma system would have a great ability from a perspective of robustness on fabrication site, excellent gate CD controllability and minimization of plasma induced damage (PID) related device performance degradation.

Accurate nano-injection system for capillary gas chromatography

The first version of nano-injection device for capillary gas chromatography (cGC) based on inkjet microchip was developed. The nano-injector could accurately control the injection volume in nano-liter, even pico-liter range. Its configuration and mechanism were discussed in detail. Adopting photolithography and plasma etching technology, we firstly fabricated the inkjet microchip and stuck to a piezoelectric device to eject droplets. Then, a special feedback tube was added to make it function as a nano-injector for cGC, which was an important design to compensate pressure difference between the evaporation chamber of cGC and the sample extrusion chamber of inkjet microchip. The injected volume can be precisely controlled by the number of injected droplets. Excellent precision (RSDs were below 10.0%, n = 5) was observed for the injection of ethanol at elevated pressure. Minimum injection volume was about 1.25 nL at present. Additionally, good repeatability of the calibration curves for the hydrocarbons ethanolic solution (the RSDs of all components were below 5.30%, n = 5) confirmed its feasibility in quantitative analysis regardless of concentration. These results suggested that it can be an accurate nano-injector for cGC.