Wafer Level Stress Distribution Impact on Dynamic Calibration Matrix Drift
Wafer-level residual stress gradients induce asymmetric die warpage that relaxes over time, causing dynamic calibration matrices to suffer severe cross-axis drift.
Aniso-Elastic Suspension
Mechanical Architecture
Structural configurations in inertial sensors provide mechanical support while allowing specific degrees of freedom for proof mass movement. The aniso-elastic suspension utilizes varying stiffness across different axes to control the response of a resonator to acceleration and rotation. The assembly establishes a predictable relationship between applied force and displacement by decoupling the primary sensing axis from secondary vibration modes.
Stiffness Differential
Stiffness gradients define how the component behaves under environmental stress. Differential geometry within the aniso-elastic suspension ensures that the resonant frequency remains stable even when thermal expansion occurs. Beam dimensions are adjusted to achieve the desired spring constant.
Acceleration Response
High precision gyroscopes require the isolation of linear acceleration from angular rate signals. An aniso-elastic suspension limits the rectified drift that occurs when vibration couples into the quadrature signal. Errors arise if the elastic center of the spring system does not align with the center of gravity of the mass.
Mechanical alignment is verified during the fabrication of the micro-electromechanical system to ensure that external shocks do not produce false rotation data.
Error Control
Quadrature error suppression relies on the symmetry of the mechanical layout. Use of an aniso-elastic suspension reduces the influence of cross-axis sensitivity on the final measurement output. Compliance with geometric tolerances during the etching process ensures that the device maintains its performance over its service life.