This PDF file contains the editorial “Editorial: New Prospect of Successors to ArF Water-Immersion Lithography” for JM3 Vol. 9 Issue 02

The main scattering mechanisms governing the transport of electrons in PMMA in an energy domain ranging from the energy of the primary electron beam down to few hundreds of meV are identified. A quantitative Monte Carlo model for the emission of secondary electrons is developed to be applied for critical dimensions extraction from high-resolution scanning electron microscopy (SEM) images. Selected results are presented, which demonstrate the accuracy of the proposed approach.

A novel hybrid energy harvester integrated with piezoelectric and electromagnetic energy harvesting mechanisms is investigated. It contains a piezoelectric cantilever of multilayer piezoelectric transducer (PZT) ceramics, permanent magnets, and substrate of two-layer coils. The effect of the relative position of coils and magnets on the PZT cantilever end and the poling direction of magnets on the output voltage of the energy harvester is explored. When the poling direction of magnets is normal to the coils plane, the coils yield the maximum output voltage, i.e., the type I and III devices. The maximum output voltage and power from the PZT cantilever of the type III device are 0.84 V and 176 µW under the vibrations of 2.5-g acceleration at 310 Hz, respectively. And the maximum output voltage and power from the coils are 0.78 mV and 0.19 µW under the same conditions, respectively. The power density from the type III device is derived as 790 µW/cm3 from piezoelectric components and 0.85 µW/cm3 from electromagnetic elements.

We demonstrate a process to fabricate highly uniform large-area polymer 3-D "woodpile" photonic crystal structures with nanometer-scale features. This fabrication process utilizes the SU-8 resist's enhanced absorption of deep-UV wavelengths to achieve resist exposure confinement to a desired depth. It also uses the high resistance of cross-linked SU-8 resist to solvents for layer-upon-layer resist application and processing. This fabrication method affords the flexibility of incorporating arbitrary design patterns for the different layers. Depending on the exposure mask area and the size of exposure window available in the mask aligner, this fabrication process can provide such devices over wafer-scale areas. This fabrication method is highly compatible with standard semiconductor processing methods and is thus well suited for mass fabrication.

We demonstrate the fabrication of micropore and nanopore features in hollow antiresonant reflecting optical waveguides to create an electrical and optical analysis platform that can size select and detect a single nanoparticle. Micropores (4 µm diameter) are reactive-ion etched through the top SiO₂ and SiN layers of the waveguides, leaving a thin SiN membrane above the hollow core. Nanopores are formed in the SiN membranes using a focused ion-beam etch process that provides control over the pore size. Openings as small as 20 nm in diameter are created. Optical loss measurements indicate that micropores did not significantly alter the loss along the waveguide.

When a thinner absorber mask is practically applied to the extreme ultraviolet lithography for ultra large scale integration chip production, it is inevitable to introduce an extreme ultraviolet (EUV) light shield area to suppress leakage of the EUV light from adjacent exposure shots. We believe that a light-shield border of the multilayer etching type is a promising structure in terms of mask process flexibility for higher mask critical dimension accuracy. We evaluate the etching impact of the absorber and multilayer on the mask flatness and image placement change through the mask process of a thin absorber mask with a light-shield border of the multilayer etching type structure. We clarify the relation between mask flatness and mask image placement shift.

This study presents a polyimide (PI) self-assembly technique for developing a 3-D surface-micromachined structure. The effects of geometric factors and curing temperatures of PI elastic joints on the lifting angles of such 3-D microstructures are investigated. Under the optimized curing condition (380°C), a maximum 74-deg lifting angle of 5.2×10⁻¹¹ kg-weight polysilicon microplate is achieved utilizing a large thermal shrinkage force of a single PI joint. Before severe cross-linkage occurred (curing at 390 to 400°C), the lifting angle of the thermally actuated 3-D microstructure is nearly in direct proportion to the length/width-thickness ratio of the PI joint (with linearity of 95.5%) and the difference between curing and room temperatures (with linearity of 92.3 to 97%). The PI-based self-assembly process is very suitable for mass production due to its high yield of fabrication (80 to 91.6%) and high compatibility with the present IC and MEMS manufacturing processes.

A lithography technique for patterning one-dimensional (1-D) nanoscale grating features based on surface plasmon (SP) interference is demonstrated both experimentally and numerically. We report a cost-effective, single-exposure maskless plasmonic lithography to generate 156-nm periodic grating lines at an exposure wavelength of 364 nm.

To identify the extreme low concentration of alpha-fetoprotein (AFP) antigen in human serum for early detection of hepatocellular carcinoma, we aim to develop a high-sensitivity and low-cost AFP biosensor using quartz crystal microbalance (QCM) and cystamine self-assembly monolayer (SAM) technologies. In this study, the surface topographies of concentrations (0.1 and 1.0 mg/mL) of AFP antibody with and without 1.25% glutaraldehyde cross-linking layer will be analyzed by an atomic force microscope system to investigate the effects of the glutaraldehyde layer on the sensing characteristics of the QCM-based AFP biosensor. According to our experimental results, the mass sensitivity was improved almost doubly (from 0.07 to 0.146 Hz mL mg⁻¹) as the glutaraldehyde layer was added between the 20-mM cystamine SAM and the low-concentration (0.1 mg/mL) AFP antibody. Either with or without the glutaraldehyde layer, higher mass sensitivity (0.163 to 0.335 Hz mL mg⁻¹) was obtained as the AFP antibody concentration increased to 1.0 mg/mL. However, a large AFP antibody requirement will increase fabrication cost and limit disposable application. We also demonstrated that high sensing linearities (95.67 to 99.6%) of the QCM-AFP biosensors can be achieved without being obviously affected by the glutaraldehyde layer and AFP antibody concentration.

The actual extreme ultraviolet lithography tools will have aberrations around seven times larger than those of the latest ArF lithography tools in wavelength normalized rms. We calculated the influence of aberrations on the size error and pattern shift error using Zernike sensitivity analysis. Mask-induced aberration restricts the specification of aberration. Without periodic additional pattern, the aberration level that can be accepted to form 22 nm dual-gate patterns was <8 mλ rms. Arranging the periodic additional pattern relaxed the aberration tolerance. With periodic additional pattern, the acceptable aberration level to form 22 nm patterns was below <37 mλ rms. It is important to make pattern periodicity for the relaxation of the aberration specification.

Because of the gradient distribution of arsenic through the thickness of an InP layer, stress gradient in the structural layer of an InP-based Fabry−Perot (FP) cavity structure could be introduced during the fabrication process. This stress gradient, usually tensile at the upper surface and compressive at the lower surface, could induce a significant out-of-plane deformation, which may eventually affect its optical performance. White-light vertical scanning interferometry is employed to measure the stress-induced deflection of InP-based cantilever and membrane components used in a FP cavity structure. Deformation patterns caused by stress gradient in various cantilever and membrane structures with different configurations and geometries are investigated through experiments and simulations. The results indicate that the stress gradient induced during the fabrication process results in varying degrees of the FP structural deformation, which is further influenced by the configurations and geometries of the structural membranes and supporting beams. Four types of membrane structures of a FP cavity device are studied, and the results are compared to that obtained using a finite element analysis.

We demonstrate a large area production of 3-D woodpile metallic photonic crystals using deep x-ray lithography and subsequent electroforming. These structures represent the ⟨110⟩ orientation of the ⟨001⟩ woodpile structures most commonly presented in the literature. This approach requires no alignment and is capable of generating a 3 unit cell thick photonic crystal in a simple three step process flow. Tilted woodpiles demonstrate band characteristics very similar to those observed from [001] woodpiles. Reflectivity tests show a band edge around 4 µm and good comparison well with numerical simulations.

A novel dual-dome micromechanical resonator and a method for fabricating it into a single or amorphous crystal silicon film layer is demonstrated. An electrostatic effect on the input resonator induces high-frequency resonant mechanical motion in the first dome plate, which is mechanically conducted into the second equivalent dome plate. Transduction from the input resonator to the output resonator is mechanically performed not by using coupling rods but by overlapping the plates. Oscillations are obtained at 8.5 MHz and 17 MHz when the resonator is buffered with a high-impedance junction gate field-effect transistor amplifier.

We present a simple fabrication technique using a hydrophobic composite elastomer for patterning an SU-8-based rib waveguide Bragg grating filter via solvent-assisted microcontact molding (SAMIM). The proposed technique utilizes a two-layered composite stamp made of polydimethylsiloxane and hard polydimethylsiloxane, which enables both the rib waveguide and surface relief grating structure to be patterned simultaneously. The SAMIM method realizes patterning at ambient temperatures with the weight of the mold applying all the pressure necessary. By allowing the mold to absorb solvent when in contact with the polymer, the solvent dissolves or swells the polymer's surface, creating the desired pattern. This composite mold successfully demonstrates the SAMIM creation of the SU-8 rib waveguide and gratings, paving the way for a facile and efficient reproduction of a polymeric rib waveguide grating filter. Based on experimental results, the stamp demonstrates an operational life span in excess of 10 successful replications, utilizing a Bragg grating test pattern with a grating period of ~492 nm, a depth of ~250 nm, and a total length of 12 mm. The resulting waveguides show a band-rejection gain of −17 dB at the center wavelength of 1545 nm and a 3-dB bandwidth of 2.5 nm.

Line-end pullback is a major source of patterning problems in low-k₁ lithography. Lithographers have been well-served by geometric metrics such as critical dimension (CD) at a gate edge; however, the ever-rising contribution of line-end extension to layout area necessitates reduced pessimism in qualification of line-end patterning. Electrically aware metrics for line-end extension can be helpful in this regard. The device threshold voltage is, with nominal patterning, a weak function of line-end shapes. However, the electrical impact of line-end shapes can increase with overlay errors, since displaced line-end extensions can be enclosed in the transistor channel, and nonideal line-end shape will manifest as an additional gate CD variation. We propose a super-ellipse parameterization that enables exploration of a large variety of line-end shapes. Based on a gate capacitance model that includes the fringe capacitance due to the line-end extension, we model line-end-dependent incremental current ΔI_on and ΔI_off to reflect inverse narrow width effect. Last, we calculate the I_on and I_off considering line-end shapes as well as line-end extension length, and we define a new electrical metric for line-end extension-namely, the expected change in I_on or I_off under a given overlay error distribution. Our model accuracy is within 0.47% and 1.28% for I_on and I_off, respectively, compared to 3-D TCAD simulation in a typical 45-nm process. Using our proposed electrical metric, we are able to quantify the electrical impact of optical proximity correction, lithography, and design rule parameters, and we can quantify trade-offs between cost and electrical characteristics.