A Piezoresistive Pressure Sensor with Optimized Positions and Thickness of Piezoresistors

Area of Science:

• Materials Science
• Electrical Engineering
• Mechanical Engineering

Background:

• Piezoresistive pressure sensors are crucial for various measurement applications.
• Silicon on insulator (SOI) technology offers advantages for micro-sensor fabrication.
• Optimization of sensor design is key to improving performance metrics like sensitivity and linearity.

Purpose of the Study:

• To design and fabricate a high-performance piezoresistive pressure sensor using SOI technology.
• To optimize the placement and thickness of piezoresistors for enhanced sensitivity and reduced nonlinearity.
• To evaluate the sensor's performance characteristics, including sensitivity, full-scale output, hysteresis, repeatability, accuracy, and temperature stability.

Main Methods:

• Numerical simulation was employed to optimize the position and thickness of four piezoresistors on the pressure-sensitive diaphragm.
• The sensor was fabricated using SOI wafers, with silicon for electrical connections simplifying the process.
• Experimental testing was conducted to characterize the sensor's performance under various pressure and temperature conditions.

Main Results:

• Optimized design with central and edge piezoresistors and a 2 μm thickness achieved maximum sensitivity and minimum nonlinearity.
• The fabricated sensor exhibited high sensitivity (37.79 mV·V^-1·MPa^-1) and a high full-scale output (472.33 mV).
• Excellent performance was demonstrated with low hysteresis (0.09% FS), good repeatability (0.03% FS), high accuracy (0.06% FS), and stable temperature characteristics.

Conclusions:

• The optimized SOI piezoresistive pressure sensor offers superior performance compared to conventional designs.
• The simplified fabrication process using silicon for electrical connections enhances manufacturing efficiency.
• This sensor represents a promising tool for accurate and reliable pressure measurements in diverse applications.