Korea Advanced Institute of Science and Technology · Engineering
Professor Jun-Bo Yoon's research lab specializes in advanced micro- and nanofabrication technologies for high-performance RF and microwave integrated circuits, with a focus on CMOS-compatible surface micromachining. The lab develops three-dimensional (3-D) suspended metal microstructures—such as spiral inductors, solenoids, and tunable capacitors—on standard silicon substrates to achieve ultra-high quality (Q) factors and improved RF performance. Key research directions include minimizing substrate loss through mechanical suspension, enabling high inductance density and tunability, and advancing flexible, transparent, and bending-insensitive force sensors for next-generation wearable and portable electronics. The lab's work bridges fundamental microfabrication techniques with practical applications in wireless communication, sensing, and integrated passive components.
Figures are computed from collected data and may differ slightly.
Fully CMOS-compatible, highly suspended spiral inductors have been designed and fabricated on standard silicon substrates (1/spl sim/30 /spl Omega//spl middot/cm in resistivity) by surface micromachining technology (no substrate etch involved). The RF characteristics of the fabricated inductors have been measured and their equivalent circuit parameters have been extracted using a conventional lumped-element model. We have achieved a high peak Q-factor of 70 at 6 GHz with inductance of 1.38 nH (a
RF performance of surface micromachined solenoid on-chip inductors fabricated on a standard silicon substrate (10 /spl Omega//spl middot/cm) has been investigated and the results are compared with the same inductors on glass. The solenoid inductor on Si with a 15-μm thick insulating layer achieves peak quality (Q-) factor of 16.7 at 2.4 GHz with inductance of 2.67 nH. This peak Q-factor is about two-thirds of that of the same inductor fabricated on glass. The highest performance has been obtaine
As a viable technological option to address today's strong demands for high-performance monolithic low-cost passive components in RF and microwave integrated circuits (ICs), a new CMOS-compatible versatile thick-metal surface micromachining technology has been developed. This technology enables to build arbitrary three-dimensional (3-D) metal microstructures on standard silicon substrate as post-IC processes at low temperature below 120/spl deg/C. Using this technology, various highly suspended
Abstract Force touch sensors have received a great deal of attention for various applications owing to their versatile ability to detect touch and pressure. To demonstrate high‐performance force touch sensors, numerous studies have been performed, focusing on high sensitivity, transparency, and mechanical durability against bending. However, it is still challenging to apply force touch sensors in flexible applications, because their sensing performance is subject to change and degraded by induce
A high-Q, tunable, micromechanical capacitor has been realized using an IC-compatible, electroplated-metal surface micromachining technology and demonstrated with quality (Q-) factors in excess of 290-the highest reported to date for on-chip tunable capacitors at frequencies near 1 GHz. The key feature in this design that makes possible such high on-chip Q is the method for capacitive tuning, which in this design is based on moving the dielectric between the capacitor plates, rather than moving
We have investigated the RF performance of the micromachined integrated spiral inductors overhanging several tens of microns from the substrate, having at least 10 /spl mu/m in copper thickness. From the experiments, it can be speculated that once the inductor is overhung by at least 30 /spl mu/m, the substrate coupling can be eliminated almost completely, even in the standard silicon substrate, as long as there is no additional support. The inductor overhanging 30 /spl mu/m from the standard si
This study proposes a reliable and self-powered hydrogen (H<sub>2</sub>) gas sensor composed of a chemo-mechanically operating nanostructured film and photovoltaic cell. Specifically, the nanostructured film has a configuration in which an asymmetrically coated palladium (Pd) film is coated on a periodic polyurethane acrylate (PUA) nanograting. The asymmetric Pd nanostructures, optimized by a finite element method simulation, swell upon reacting with H<sub>2</sub> and thereby bend the PUA nanogr
A novel and high-yield fabrication process has been devised for monolithic integration of solenoid inductors. In order to simplify the fabrication steps, we decompose the solenoid inductor into two parts, bottom conductor lines and air bridges. The air bridge is formed as a single body during a single electroplating step. This single-step fabrication of the air bridges is possible by forming a three-dimensional (3D) photoresist mold using multiple exposures with varying exposure depths, followed
Electroplated solenoid-type integrated inductors (SI/sup 2/s) have been demonstrated to have high performance and small area occupation for GHz applications, using a new, simple, and highly adaptable 3D surface micromachining technology. The method utilizes simply modified conventional photolithography and well-established electroplating at a low process temperature (<120/spl deg/C), so that the post-IC process and batch fabrication are possible. We have fabricated a 20-turn SI/sup 2/ with an in
The high explosiveness of hydrogen gas in the air necessitates prompt detection in settings where hydrogen is used. For this reason, hydrogen sensors are required to offer rapid detection and possess superior sensing characteristics in terms of measurement range, linearity, selectivity, lifetime, and environment insensitivity according to the publicized protocol. However, previous approaches have only partially achieved the standardized requirements and have been limited in their capability to d
Palladium (Pd) has been drawing increasing attention as a hydrogen (H<sub>2</sub>) detecting material due to its highly selective sensitivity to H<sub>2</sub>. However, at H<sub>2</sub> concentrations above 2%, Pd undergoes an inevitable phase transition, causing undesirable electrical and mechanical alterations. In particular, nonlinear gas response (Δ<i>R</i>/<i>R</i><sub>0</sub>) that accompanies phase transition has been a great bottleneck for detecting H<sub>2</sub> in high concentrations,
Recently, geometrically structured nanomaterials have received great attention due to their unique physical and chemical properties, which originate from the geometric variation in such materials. Indeed, the use of various geometrically structured nanomaterials has been actively reported in enhanced-performance devices in a wide range of applications. Recent significant progress in the development of geometrically structured nanomaterials and associated devices is summarized. First, a brief int
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