You are here

Investigation of Polymer Bonding Processes for MEMS Packaging

Kun Zhao, Changhai Wang
Micro-electro-mechanical systems (MEMS) devices are fabricated using semiconductor processing techniques, which range in size from micrometers to millimetres... [read more]

Micro-electro-mechanical systems (MEMS) devices are fabricated using semiconductor processing techniques, which range in size from micrometers to millimetres. The market for MEMS is growing rapidly over years driven by the promise to miniaturize industrial and domestic products. Packaging is one of the most important aspects for MEMS as it is the bridge that interconnects all the components into electronic systems. A key challenge in MEMS packaging is the development of low temperature bonding processes. Polymer is often used as a sealing ring material for MEMS packaging. The objective of the project is to investigate novel hotplate and laser based bonding processes using benzocyclobutene (BCB) and other polymer materials for reliable packaging of MEMS. A high-yield bonding procedure has been established for hotplate based BCB bonding. Bonding of both planar and non-planar surfaces using BCB has been demonstrated by producing a 0.5 µm thick, 400 µm wide titanium feedthrough lines on the surface of the silicon substrates. Laser assisted bonding process using novel beam forming elements and BCB has been demonstrated. A high-power diode laser was used to produce the required temperature rise for BCB curing/bonding through the absorption of the laser radiation by the silicon substrate. Defect free bonding was completed in 10 seconds using 50 W of laser power. The localised heating and rapid bonding make this technique ideal for temperature sensitive MEMS devices.