A micro-thin-film getter–heater unit for high vacuum capsulation of MEMS devices

Abstract

In this paper, we proposed a micro-getter unit with a square thin-film getter formed atop a thin-film heater for vacuum packaging of a Micro-Electro-Mechanical System (MEMS) device. This innovation through an integrated module unit can be fabricated by MEMS compatible processes and can be sealed together with a MEMS device by wafer level package technology sequentially. It has the advantage of locally and repeatedly activating the getter by supplying a DC power to the micro-thin-film heater. Two models have been studied comparatively in this work, in which a conventional solid structure (SS) model with a micro-heater directly above a silica glass substrate was used as a reference model for comparison with the newly designed innovative floating structure (FS) model with a micro-heater floating over a cavity in a silicon substrate. According to a finite element method simulation based on Fourier’s law of heat conduction, the FS model showed better thermal efficiency than the SS model during the activation process. For a square micron thin-film getter with a size as 1000 × 1000 × 5 µm3, a rather low input voltage as 2 V can raise the temperature of the getter up to 300 °C calculated by the FS Model, while the SS model requires a much higher input voltage as 18 V to reach the same temperature.