Monolithic Si-based micro-pressure sensor and manufacturing method thereof

Abstract

The present invention discloses a monolithic Si-based micro-pressure sensor and a manufacturing method thereof. A back island structure is made in an etch pit in a silicon chip, the back island structure is internally provided with a back island used for stable measurement. Compared to a traditional micro-pressure sensor with a thickness about 400 micrometers, the back island is small in volume, the distance between the bottom surface of the back island and a frame plane is far larger than 5-10 micrometers, the back island in the monolithic Si-based micro-pressure sensor cannot be limited by the thickness of the silicon chip to improve the rate of output and reduce the cost; compared to a traditional E-type structure, the monolithic Si-based micro-pressure sensor can overcome the self-gravity effect of a large back island so as to improve the stability; the monolithic Si-based micro-pressure sensor can avoid the problem that the device is failed in effect caused by bonding of the backisland and glass; and moreover, the monolithic Si-based micro-pressure sensor can form an elastic silicon film with good thickness consistency and good in flexible consistency so as to be suitable forlarge-scale production.

Description

technical field [0001] The invention relates to the field of sensor technology, in particular to a monolithic silicon-based micro-pressure sensor and a manufacturing method thereof. Background technique [0002] Micro pressure sensors usually refer to pressure sensors with a range of less than 10Kpa. This type of sensor requires high sensitivity, that is, it will have a large electrical signal output under the action of a small pressure. For example, when used as a respiration sensor, it is necessary to detect the weak respiration signal of the human body. In order to achieve this purpose, the core part of the micro-pressure sensor, that is, the elastic silicon membrane, needs to be made very thin. The silicon substrate with a thickness of 400 microns is processed through the integrated circuit planar process, and the etching window is etched on the back, and the front is protected, and it is etched in a silicon single crystal etching solution, so that the thickness of the...

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Problems solved by technology

However, the E-type structure has the following disadvantages: (1) the large back island occupies a large area. In order to obtain a good effect, the area of ​​the micro-pressure sensor chip is required to be large, resulting in a low output rate; (2) due to the large back island The area is large, so its self-weight effect cannot be ignored, forming a large-value inherent zero-point output signal that changes with the position of the micro-pressure sensor, thereby affecting the stability of the measurement; (3) Anodic bonding of the chip and glass At this time, the gap between the top of the big back island and the glass is only 5-10 microns, which will generate a large electrostatic Coulomb force, pulling the big back island to the surface of the glass, causing the big back island and the glass to bond together, making the device invalid; (4) Since the silicon dioxide layer is only provided on the bottom surface of the large back island, it is difficult to control the thickness of the elastic silicon film when etching the silicon substrate, and the output rate is low, so it is not suitable for large-scale production

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