Development and post-dicing wet release of MEMS magnetometer: an approach

Purpose Si-based micro electro mechanical systems (MEMS) magnetometer does not require specialized magnetic materials avoiding magnetic hysteresis, ease in fabrication and low power consumption. It can be fabricated using the same processes used for gyroscope and accelerometer fabrication. The paper reports the dicing mechanism for the released MEMS xylophone magnetic sensor fabricated using wafer bonding technology and its characterization in ambient pressure and under vacuum conditions. The purpose of this paper is to dice the wafer bonded Si-magnetometer in a cost-effective way without the use of laser dicing and test it for Lorentz force transduction. Design/methodology/approach A xylophone bar MEMS magnetometer using Lorentz force transduction is developed. The fabricated MEMS-based xylophone bars in literature are approximately 500 µm. The present work shows the released structure (L = 592 µm) fabricated by anodic bonding technique using conducting Si as the structural layer and tested for Lorentz force transduction. The microstructures fabricated at the wafer level are released. Dicing these released structures using conventional diamond blade dicing may damage the structures and reduce the yield. To avoid the problem, positive photoresist S1813 was filled before dicing. The dicing of the wafer, filled with photoresist and later removal of photoresist post dicing, is proposed. Findings The devices realized are stiction free and straight. The dynamic measurements are done using laser Doppler vibrometer to verify the released structure and test its functionality for Lorentz force transduction. The magnetic field is applied using a permanent magnet and Helmholtz coil. Two sensors with quality factors 70 and 238 are tested with resonant frequency 112.38 kHz and 114.38 kHz, respectively. The sensor D2, with Q as 238, shows a mechanical sensitivity of 500 pm/Gauss and theoretical Brownian noise-limited resolution of 53 nT/vHz. Originality/value The methodology and the study will help develop Lorentz force–based MEMS magnetometers such that stiction-free structures are released using wet etch after the mechanical dicing.

Modification of diazoquinone-novolac photoresist films by boron ion implantation

Diazoquinone-novolac photoresist films implanted with B+ ions were studied by the method of attenuated total reflection (ATR). Films of positive photoresist FP9120 with a thickness h of 1.0 and 2.5 mm were deposited by centrifuging on p-type silicon plates with (111) orientation. Implantation with 60 keV B+ions in the dose range of 1015–1016 cm–2 in the constant ion current mode (current density 4 mA/cm2 ) was carried out at room temperature in a residual vacuum not worse than 10–5 Pa using the «Vesuvius-6» ion beam accelerator. The attenuated total reflection spectra were recorded in the range 400 – 4000 cm–1 by ALPHA spectrophotometer (Bruker Optik GmbH, Germany) at room temperature. It was shown that ion implantation leads to intensive transformation of the photoresist beyond the range of ions, which is characterized by the appearance in the spectrum of intense bands with peaks at 2151 and 2115 cm–1, due to stretching vibrations of double cumulative bonds, in particular С——С——О. In the implanted samples, a shift to the low-energy region of the maxima of the stretching vibrations of C—H bonds, plane deformation vibrations of O—H bonds and pulsating vibrations of the carbon skeleton of aromatic rings as well as the redistribution of intensities between closely spaced maxima, were observed.

DESIGN AND CHARACTERIZATION OF SPIN COATER TO SUPPORT NATIONAL SEMICONDUCTOR INDUSTRY

<p>Recently, semiconductor industry grows rapidly due to high demand of modern electronic system. In addition, the value of investments in Indonesia electronic industries also more than doubled during 2015-2017. This increase in investment will certainly have an impact on the increasing the needs for electronic / semiconductor component processing machines. To support it, well performed spin coater then were designed. The characterization of spin coating process was done at BSN (formerly was known as Research Center for Metrology LIPI) using roughness measuring instrument/ profilometer that traceable to PTB (Germany) to guarantee the validity of the measurement results. Characterization experiment used positive photoresist SPR3018 to see the performance of system designed. Three different experiments were performed to determine the impact of spin speed and spin time to photoresist thickness and uniformity. The characterization shown that on spin speed increased, the photoresist was deployed thinner. The thickness of the photoresist is inversely proportional to the square root of spin speed. Furthermore, the longer spin coating time, it increases the tendency of concave surface. This work is expected to benefit the practitioners of electronic systems, semiconductor industries, and even SNI conceptors.</p>

Formation and Characterization of Hole Nanopattern on Photoresist Layer by Scanning Near-Field Optical Microscope

Patterning of lines of holes on a layer of positive photoresist SX AR-P 3500/6 (Allresist GmbH, Strausberg, Germany) spin-coated on a quartz substrate is carried out by using scanning near-field optical lithography. A green 532 nm-wavelength laser, focused on a backside of a nanoprobe of 90 nm diameter, is used as a light source. As a result, after optimization of parameters like laser power, exposure time, or sleep time, it is confirmed that it is possible to obtain a uniform nanopattern structure in the photoresist layer. In addition, the lines of holes are characterized by a uniform depth (71–87 nm) and relatively high aspect ratio ranging from 0.22 to 0.26. Numerical modelling performed with a rigorous method shows that such a structure can be potentially used as a phase zone plate.

Fabrication of a Three-Layer PDMS Pneumatic Microfluidic Chip for Micro Liquid Sample Operation

The emphasis of this paper lies in the fabrication of a three-layer polydimethylsiloxane chip for micro liquid sample operation. In this paper, the microchannels with a rectangular control layer cross section are fabricated based on a dry-film negative photoresist mold, while the microchannels with a rounded liquid layer cross section are fabricated by a positive photoresist reflow mold. The relationships between temperature and the time of reflow and the arc level of the liquid layer mold are discussed. Different ratios, curing temperatures, and curing times are used to fabricate the two PDMS layers to improve their toughness and plasticity separately. The PDMS slabs with microstructure networks are treated with oxygen plasma to improve their surface properties. The improved surface properties serve to reduce the temperature and time, and improve the sealing strength, which is as effective as adding PDMS in varying ratios. The micro liquid sample operation experiments show that high levels of pinching off and mixing performances on pneumatic microfluidic chips are obtained more easily.

Using the Taguchi-Genetic Algorithm to Improve Lithographic Photoresist Operating Conditions of Touch Panels to Upgrade After-Develop Inspection

In order to use touch control products more conveniently, a general objective is to develop lighter and smaller touch panels. A touch panel using the one glass solution (OGS) is an important development. The black matrix (BM) in an OGS touch panel is used as a black frame. The photoresist is divided into a positive photoresist and a negative photoresist. The BM photoresist is negative. After coating, exposure, and development in the BM process, after-develop inspection is implemented to check if the appearance is abnormal. It is quite difficult to rework the negative photoresist process. There is still room for improving the BM photoresist process capability Cpk. Thus, in order to reduce the customer complaint rate and enhance stability, the photolithography process is improved to enhance Cpk. Among the BM black negative photoresist forming process conditions of OGS products, the pre-baking time is the most important process control factor. The method set up herein improves the original Cpk = 0.90. This study employs the fast messy genetic algorithm (fmGA) to select the optimum orthogonal array of the Taguchi method, so as to implement the decision process of optimum parameter design. The Cpk of the optimum parameter is 2.12.

Low Cost Method for Generating Periodic Nanostructures by Interference Lithography Without the Use of an Anti-Reflection Coating

ABSTRACTInterference lithography has proven to be a useful technique for generating periodic sub-diffraction limited nanostructures. Interference lithography can be implemented by exposing a photoresist polymer to laser light using a two-beam arrangement or a one-beam configuration based on a Lloyd’s Mirror Interferometer. For typical photoresist layers, an anti-reflection coating must be deposited on the substrate to prevent adverse reflections from cancelling the holographic pattern of the interfering beams. For silicon substrates, such coatings are typically multilayered and complex in composition. By thinning the photoresist layer to a thickness well below the quarter wavelength of the exposing beam, we demonstrate that interference gratings can be generated without an anti-reflection coating on the substrate. We used ammonium dichromate doped polyvinyl alcohol as the positive photoresist because it provides excellent pinhole free layers down to thicknesses of 40 nm, and can be cross-linked by a low-cost single mode 457 nm laser and etched in water. Gratings with a period of 320 nm and depth of 4 nm were realized, as well as a variety of morphologies depending on the photoresist thickness. This simplified interference lithography technique promises to be useful for generating periodic nanostructures with high fidelity and minimal substrate treatments.