MANUFACTURING TECHNOLOGY OF PRESSURE SENSOR’S SENSITIVE ELEMENTS BASED ON “SAPPHIRE – VITERIOUS DIELECTRIC – CERAMIC” JUNCTION

Abstract

Today pressure transmitters have high requirements such as reliability, quality, measurement
accuracy, the ability to work in extreme conditions and resistance to aggressive environments.
The main problems in achieving these target indicators are: the high cost of the original
products, the laboriousness of the technological process in serial production, and the limitations
that affect the accuracy of the indicators of the original devices. Solving these problems is the
subject of this article. To solve these problems and improve the physical and mechanical properties
of pressure sensor’s sensitive elements, the following tasks are considered in the article: development
of a pressure-sensing element design based on the silicon-on-sapphire (SOS) structureresearch on the method of its connection with a ceramic body element and development of a technological
route for manufacturing the structure based on “sapphire – vitreous dielectric – ceramic”
junction. As a result, the pressure sensor based on the SOS structure has high sensitivity,
stability, practically no mechanical hysteresis, and can operate in a wide temperature range from
-60 to +350°C when exposed to radiation. In turn, the use of a ceramic base makes it possible to
reduce the temperature error of the sensor due to better matching of the coefficient of linear thermal
expansion (CLTE) of ceramic (85–100×10-7 K-1) and sapphire substrate (60–75×10-7 K-1), as
well as reduce the cost of the technological process due to the use of ceramics instead of expensive
titanium alloys and complex metalworking. Thus, the structure "sapphire – vitreous dielectric –
ceramic" shows the possibility of increasing the sensitivity of the sensor and reducing the error
while expanding its functionality, simplifying the design and improving manufacturability