Micro welding of aluminum for post process electrode gap reduction using femtosecond laser

This paper presents a new technology, which allows the reduction of the micro dimensional trench width below the technological limitations of the Deep Reactive Ion Etching (DRIE) process. The high-accuracy and high-throughput femtosecond laser-micro-welding of aluminum was performed for the first time by Micro Electrical Mechanical System (MEMS) fabrication to realize this permanent trench width reduction. Therefore, this technology has been applied for the electrode gap reduction of high precision vibration sensors, based on the capacitive working principle, resulting in a fourfold improvement of the sensitivity without changing the size of the sensor chip itself.