The Technical Journal is ULVAC Group's technical information magazine. The latest issue can be downloaded from this site. Once you have entered and submitted your customer information, you can download the Technical Journal.
We describe in this article MEMS sensors for automotive applications and related functional material films, a deposition technology for which we have developed. The performance of automobiles is enhanced by their control systems, leading to reduced fuel consumption, higher safety, and other advantages. A MEMS sensor is an essential component of a control system because it can detect environmental changes and feed this information back to the system. The importance of automotive MEMS sensors is increasing due to the design requirements for nextgeneration automobiles, such as self-driving and all-electric vehicles. It is anticipated that by applying a variety of functional materials, a MEMS sensor with new functions will be realized. More specifically, this article introduces the PZT and VOx functional material films that have been developed by the authors. Both films are deposited by the sputtering method, demonstrating that films characterized by excellent performance can be obtained by applying a unique sputtering and process technology.
3D sensing devices for autonomous vehicles have seen major technical advances in recent years. Light Detection and Ranging (LiDAR) has emerged as the technology most compatible with these sensors, as it possesses characteristics that promise to enhance the functionality of autonomous driving. Vertical Cavity Surface Emitting Lasers (VCSELs) are economical and compact enough to serve as light sources for LiDAR. Dry process is the key to VCSEL fabrication. However, this fabrication method poses various challenges. To produce these devices, we have been developing a high-uniformity etching technology, along with an Interferometry End Point monitoring system. This article elaborates on the solutions we implemented to address these challenges.
Because the market for lithium ion batteries is expected to grow rapidly, efforts are underway to develop an advanced rechargeable Li-ion battery. One approach for such a rechargeable battery that is attracting attention uses lithium metal as the anode, because the result would be a high-capacity, lightweight battery that is ideal in terms of energy density. However, in order to put a lithium metal anode into practical use, it is necessary to solve the problem of dendrites that occur during repeated cycles of charging and discharging. Other issues that need to be addressed include safety and battery life. Compared to conventional roll-press Li foil, our vacuum evaporated Li film has shown excellent cycle performance. We were also able to stabilize the active Li surface after deposition by applying a "chemical-passivation" process that we developed.
Carbon nanotube (CNT) electrodes vertically aligned on a copper foil substrate have been fabricated by using a thermal chemical vapor deposition (CVD) method. In the electrode, superior electron conduction paths are formed over the entire electrode. The electron conduction paths are due to the fact that the CNTs are vertically aligned on the substrate with strong adhesion. Such a vertically aligned CNT electrode has been applied to a lithium-ion capacitor (LIC) as a negative electrode material. The fabricated LIC shows high energy density compared to an electric double-layer capacitor (EDLC) to which a commercially available activated carbon electrode material has been applied. This fabricated LIC also demonstrates high power density compared to an LIC to which a commercially available graphite anode has been applied.
Dramatic changes have been occurring in the automotive industry. Among the targets of technological development has been the shift to all-electric vehicle (EVs) and fuel-cell vehicles (FCVs). Batteries, motors, and power devices represent the most essential technologies for EVs and FCVs. A power device is a semiconductor element that functions as a switch for converting the electric power. Examples include metal oxide semiconductor field effect transistors (MOSFETs) and insulated gate bipolar transistors (IGBTs). Power device technology is currently based primarily on silicon (Si) wafers. Silicon carbide (SiC) and gallium nitride (GaN) are gaining attention as next-generation alternatives due to their high voltage resistant property with low electric resistance, which is well suited to power devices. ULVAC is working on productivity enhancement for thin Si wafer processing equipment, ion implantation equipment for SiC, and process development of activating annealing to form a p-type region in GaN power devices based on magnesium (Mg) ion implantation.
Magnets are produced by means of many processes, such as the alloy production process, hydrogen embrittlement process, sintering process, and grain boundary diffusion process. To produce the highperformance magnets required for use in vehicle motors, ULVAC provides an appropriate furnace for each process. The "Magcaster‑600" is a melting furnace for the alloy production process for producing magnets with good grinding characteristics. The "FHH series" includes hydrogen furnaces for the hydrogen embrittlement process without exposure to the air. The "FSC series" provides inline-type heat treatment furnaces for the sintering and aging processes. The "Magrise series" features heat treatment furnaces for the grain boundary diffusion process used to defuse heavy rare metals into neodymium. This article introduces the features of the line of furnaces manufactured by ULVAC for the production of magnets for installation in vehicle motors.