Secondary stress isolation structure applied to MEMS force sensitive device

Abstract

The invention discloses a secondary stress isolation structure (3) applied to a MEMS force sensitive device. The structure comprises an external framework structure (14) and a force sensitive structure (9) arranged in the external framework structure (14). The external framework structure (14) comprises an internal framework (15). The upper and lower ends of the internal framework (15) are connected to corresponding stress attenuation beams (13) through at least one stress concentration beam (12). The stress attenuation beams (13) are connected to fixed anchor points (10) located in flexible connections (11) through the plurality of flexible connections (11). In the invention, secondary stress release can be realized; the flexible connections (11) are first order stress isolation; the stress attenuation beams (13) and the stress concentration beam (12) are stubby stiffening bars, form a transition framework and are taken as secondary stress isolation; and stresses generated during a sensitive structural technology and a packaging process can be isolated on a sensitive structural layer.

Description

technical field [0001] The invention relates to the technical field of force sensitive devices, in particular to a secondary stress isolation structure applied to MEMS force sensitive devices. Background technique [0002] MEMS sensors, or Microelectro Mechanical Systems, is a multidisciplinary cutting-edge research field developed on the basis of microelectronics technology. After more than 40 years of development, it has become one of the major scientific and technological fields attracting worldwide attention. It involves various disciplines and technologies such as electronics, machinery, materials, physics, chemistry, biology, and medicine, and has broad application prospects. Among them, MEMS pressure sensors, accelerometers, gyroscopes, etc. are typical force-sensitive devices. They are mostly used for high-precision measurement of pressure, displacement (acceleration) and attitude (angular velocity), with small size, low power consumption, and integrated circuits. ...

AI Technical Summary

Problems solved by technology

The stress isolation of such a scheme will inevitably fail to isolate the stress generated by the sensor chip during the MEMS process (such as the deposition of different materials, bonding and other process steps), such stress is usually caused by the temperature change of different materials before and after the completion of the process steps. The mismatch of thermal characteristics and the subsequent thermal stress cannot be ignored.

[0005] At present, relevant research has been done on the stress isolation of sensitive structural layers before. In 2016, Zhang Jing et al. proposed a self-calibrating silicon microresonant accelerometer structure (201610955241.0) that is not sensitive to stress, aiming at the problem of thermal stress generated by MEMS process steps The design scheme of the sensitive structural layer of the accelerometer is given. The fixed anchor point and the structural frame are connected by flexible beams, which improves the stress isolation effect of the MEMS process to a certain extent, but there are still some residual stress affecting signals in the sensitive structural layer. detection

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