Low-cost post-CMOS integration of electroplated microstructures for inertial sensing

Abstract

This paper presents an additive integration technology for fabrication of MEMS with an electroplating technology on top of a CMOS signal processing circuit. It reports on the development of an inertial sensor-array device for automotive applications and shock-monitoring systems. This device can be manufactured using a low-cost CMOS production line and adding the mechanical sensor elements via a specialized back-end process. The basic fabrication process for the additive electroplating technology and a first device for inertial sensing was reported by the group at MME'97 [T. Tönnesen, O. Lüdtke, J. Noetzel, J. Binder, G. Mader, Simulation, design and fabrication of electroplated acceleration switches, J. Micromech. Microeng. 7 (1997) 237–239.]. The additive electroplating technology represents a new alternative to other devices realized with bulk and surface micromachining as described, e.g., in Analog Devices [Analog Devices, Monolithic accelerometer with signal conditioning ADXL50, Application Notes, 1995.]. This paper concentrates on improvements in the fabrication technology and the development of the wafer-level capping and back-end packaging sequence for a sensor-array device, which can be manufactured within an industrial processing line.