Silicon micro-resonance mode pressure sensor core and manufacturing method

Abstract

The invention discloses a silicon micro-resonance mode pressure sensor core and a manufacturing method, and belongs to the field of sensors, wherein the complex technologies such as silicon-silicon direct bonding and silicon slice thinning are not used, and large residual stress is prevented from being led in during the manufacturing process of harmonic oscillators. The silicon micro-resonance mode pressure sensor core comprises a lower layer substrate and an upper layer substrate, and the lower layer substrate and the upper layer substrate are bonded into a whole. The lower layer substrate is provided with a resonance beam, a pressure sensitive membrane, a lower layer exciting electrode, a voltage dependent resistor and a lower layer lead bonding pad. The lower layer exciting electrode and the voltage dependent resistor are arranged on the upper surface of the resonance beam. The pressure sensitive membrane is arranged at the bottom of a resonant cavity. An oscillating trough and an upper layer exciting electrode are arranged on the upper layer substrate, wherein the oscillating trough is formed in the lower surface of the upper layer substrate, and the upper layer exciting electrode covers the surface of the bottom of the oscillating trough. The oscillating trough formed in the lower surface of the upper layer substrate and the resonant cavity where the resonance beam is located form a closed space. The lower layer exciting electrode corresponds to the upper layer exciting electrode in position. An SOI silicon slice is selected and used as the lower layer substrate; a glass sheet is selected and used as the upper layer substrate.

Description

technical field [0001] The invention relates to a core body of a silicon micro-resonant pressure sensor and a manufacturing method thereof, belonging to the field of sensors. Background technique [0002] Silicon microresonant pressure sensors often use electrostatic excitation / piezoresistive detection, electrothermal excitation / piezoresistive detection, electromagnetic excitation / electromagnetic detection, and electrostatic excitation / capacitance detection. Compared with other working methods, electrostatic excitation / piezoresistive detection has the advantages of fast establishment speed, strong anti-interference ability of the detection method, small excitation heat generation, low power consumption, and easy miniaturization. However, in the existing manufacturing methods of silicon microresonant sensors, some of them are difficult to adopt this working method, and even some of them can be used, they also have their own shortcomings. [0003] For example, Greenwood et al...

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Problems solved by technology

However, in the existing silicon microresonant sensor manufacturing methods, some are difficult to adopt this working method, and some even if they can be used, they also have their own shortcomings.

[0003] For example, Greenwood et al. of GE Company used the anisotropic etching of concentrated boron self-stop technology to make a resonant sensor. Because the boron concentration on the silicon surface is too high, it has exceeded the effective range of the piezoresistive effect, so the device is not suitable for piezoresistive detection.

Moreover, the diffusion of concentrated boron introduces high internal stress, which will affect the long-term stability of the device; IKEDA et al. of Japan Suohe Co., Ltd. proposed the technology of using epitaxial growth and sacrificial layer technology to make a resonant beam built in a vacuum cavity. This technology also requires concentrated boron doping, so piezoresistors cannot be made on the resonant beam, and due to the limitation of the thickness of the sacrificial layer, the resonant range of the resonator is limited to a certain extent; / Resonant pressure sensor with piezoresistive detection method, but requires the use of silicon-silicon bonding and silicon wafer thinning technology

This technology has extremely high requirements on the flatness of the silicon wafer, and the non-uniformity of the thickness of the original silicon wafer and the non-uniformity of the thinning process itself will reduce the consistency of device performance

The Institute of Electronics of the Chinese Academy of Sciences proposed a resonant pressure sensor based on silicon nitride, but its resonant oscillator structure uses a 10μm silicon nitride beam, and the residual stress is relatively large

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