Novel Pressure Sensors Using Epitaxially Stacked Si/Al2O3/Si Structures for High-Precision Thickness Control of Silicon Diaphragms

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Abstract
Using epitaxial Al2O3 films as an etch-stop layer, Si-on-insulator (SOI) pressure sensors have been fabricated on a heteroepitaxially grown Si(100)/Al2O3(100)/Si(100) substrate. The epitaxially stacked SOI structure was formed by successive chemical vapor deposition of Al2O3 and Si on a 2-inch Si(100) substrate. The implemented sensors have a high sensitivity of 0.28 mV/V·kPa for a 93.3 kPa full-scale pressure range, with a nonlinearity and hysteresis of less than +0.2%FS and +0.09%FS, respectively. The pressure sensitivity variation can be controlled to within a standard deviation of ±2.0%. The shifts in sensitivity and offset voltage of the fabricated pressure sensors are less than -0.36% and +0.22%, respectively, in the temperature ranges of from -20°C to +100°C. The epitaxially stacked SOI structure is a highly promising material for the development of high-resolution pressure sensors with no-variation pressure sensitivity.