Realisation of silicon piezoresistive accelerometer with proof mass-edge-aligned-flexures using wet anisotropic etching

This Letter presents simulation, fabrication and testing of a high-performance quad-beam silicon piezoresistive accelerometer with very low cross-axis sensitivity. Cross-axis sensitivity in piezoresistive accelerometers is an important issue particularly for high-performance applications. In the present Letter, low cross-axis sensitivity is achieved by improving the device stability by placing four flexures in line with the proof mass edges. The accelerometer device is realised in a single-step double-sided bulk micromachining technique using a 5% dual- doped tetra methyl ammonium hydroxide solution as an anisotropic etchant. Test results of four fabricated devices show an average prime- axis sensitivity of 559.5 μV/g/5 V, a maximum cross-axis sensitivity of 0.62% full scale (FS acceleration = 13 g) of the prime-axis sensitivity and nonlinearity at a level of 0.5% of FS which are comparatively better than already reported devices and commercially available piezoresistive sensors.