Abstract
The influence of diaphragm bending stiffness distribution on the stress concentration characteristics of a pressure sensing chip had been analyzed and discussed systematically. According to the analysis, a novel peninsula-island-based diaphragm structure was presented and applied to two differenet diaphragm shapes as sensing chips for pressure sensors. By well-designed bending stiffness distribution of the diaphragm, the elastic potential energy induced by diaphragm deformation was concentrated above the gap position, which remarkably increased the sensitivity of the sensing chip. An optimization method and the distribution pattern of the peninsula-island based diaphragm structure were also discussed. Two kinds of sensing chips combined with the peninsula-island structures distributing along the side edge and diagonal directions of rectangular diaphragm were fabricated and analyzed. By bonding the sensing chips with anti-overload glass bases, these two sensing chips were demonstrated by testing to achieve not only high sensitivity, but also good anti-overload ability. The experimental results showed that the proposed structures had the potential to measure ultra-low absolute pressures with high sensitivity and good anti-overload ability in an atmospheric environment.
Highlights
Attributed to their low-cost and simple fabrication process, micro electromechanical systems (MEMS) piezoresistive pressure sensors had been widely applied in industry for several decades.Sensors with high sensitivity are often needed in a wide variety of fields
As high sensitivity combined with low non-linearity are often very attractive performance features for a sensing chip, flat silicon diaphragms were generally modified with additional lump or boss structures to stiffen the diaphragm
The measuring sensitivity of a silicon-based piezoresistive pressure sensor is mainly determined by the stress concentration conditions in the stress concentration region (SCR) of the sensing chip
Summary
Attributed to their low-cost and simple fabrication process, micro electromechanical systems (MEMS) piezoresistive pressure sensors had been widely applied in industry for several decades. As high sensitivity combined with low non-linearity are often very attractive performance features for a sensing chip, flat silicon diaphragms were generally modified with additional lump or boss structures to stiffen the diaphragm. These features improved the non-linearity by limiting the stretch deformation of the diaphragm, which is a significant cause of non-linearity [29]. Hein et al [26] used a structured diaphragm with four flexible beams and a rigid diaphragm centre to reduce nonlinearity effects They presented piezoresistive micro sensors for the 300 Pa range with high sensitivity and excellent linearity. The sensing chips were bonded on an anti-overload glass base with a stepped structure, which guaranteed the proposed sensor had a good anti-overload ability
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