Supply Allocation Exposure across Dual Sourced Low Tier Commercial Sensor Topologies
Dual sourcing low tier commercial sensors demands matching ASIC DSP group delays and thermal offset drift profiles to prevent host control loop instability.
DRIE Sidewall Taper
Etch Profile
Vertical angle deviations from true perpendicularity along plasma-etched silicon trench walls alter micro-machined beam geometries. In deep reactive ion etching, DRIE sidewall taper defines the angular slope of etched features relative to the normal axis of the wafer surface. Structural impact governs comb-drive electrostatic forces and mechanical spring constants.
Boundary limits occur when etch depths remain shallow enough that profile slope becomes negligible.
Anisotropic Mechanism
Alternating cycles of SF6 etching and C4F8 polymer passivation form the Bosch process mechanism. Imbalanced cycle timing or insufficient passivation creates positive or negative DRIE sidewall taper along deep trenches. High aspect ratio trenches suffer from ion deflection near feature bottoms due to local charge accumulation.
Plasma density uniformities directly dictate trench profile consistency across full 200 millimeter wafers.
Capacitance Variance
Non-vertical trench profiles alter the cross-sectional area of flexural suspensions, changing spring constants. In capacitive MEMS accelerometers, DRIE sidewall taper creates non-linear capacitance response curves relative to proof mass displacement. Cross-axis sensitivity increases when symmetrical suspension beams acquire asymmetric cross-sections.
Calibration procedures must compensate for initial structural stiffness variations induced by etching profiles.
Process Parameter
Scanning electron microscopy on cross-sectioned test wafers quantifies sidewall slope angles. Process engineers adjust passivating gas flow rates and RF bias power to maintain slope specifications within strict limits.