Digital Repository, Youth Symposium on Experimental Solid Mechanics

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Crack propagation in micro-chevron-test samples of direct bonded wafers
Klaus Vogel, Alexey Shaporin, Dirk Wuensch, Detlef Billep

Last modified: 2010-09-06


Micro Electro Mechanical Systems (MEMS) are applied in a wide industrial range. Their structures become more
complex by using different materials in one sample. MEMS have at least one typical component size in submillimetre
range (smaller than 100 μm) which determines its function [1]. They often consist of two or more
components and have to be joined by wafer bonding. To ensure the quality during the manufacturing process as well as to
provide data for further FE-simulations, significant material parameters are required to characterise new structures.
The behaviour of the structure depends on the bonded interface and the bonding process itself. Wafer bonding describes
all technologies for joining two or more substrates directly or using certain intermediate layers. Current investigations are
focused on the so-called low temperature bonding without intermediate layers and temperatures below 400 °C [2]. Low
temperature bonding requires a pre-treatment of the wafer surfaces in a plasma, pre-bonding at room temperature and
heating to temperatures between 200 °C and 400 °C [3]. Additional to the bonded materials, the toughness of the bonded
interface is also directly related to the bonding process. An increased temperature leads to a higher toughness of the
bonded interface.
The fracture toughness is a suitable value to describe the damage behaviour of the bonded interface. Based on a microchevron-
specimen, the fracture toughness of this specimen can be determined numerically and experimentally. The
experimental determination can be executed by combining experiment with numerical analysis.

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