Kiyoko Yamanaka

Laterally-driven deformation-robust MEMS gyroscopes with three sets of symmetrically arranged folded-beam suspensions

Microelectromechanical systems (MEMS) vibratory gyroscopes are used in a wide range of applications. Gyroscopes which have long-term stability and high-reliability even when they are used in harsh environments such as in a wide range of temperatures will be useful for automotive systems and robotics applications. We report a deformation-robust gyroscope, which has three sets of symmetrically arranged folded beams (SAF), which cancel and/or dissipate deformation or internal stress over a wide range of temperatures. In addition, we found that a triangularly supported one-sided open frame by the SAF separated spurious modes from the drive and sensing modes.

Wafer-level two-step bonding process for combined sensor with two different pressure chambers

We developed a wafer-level two-step anodic bonding process for a combined sensor with two different pressure chambers: ambient and low vacuum pressure. This two-step bonding process features: a bonding and non-bonding area controlled with a glass bump array, an anodic bonding process with plastic deformation of the glass bumps at high temperature and high loading, and two different pressure chambers formed with a sequence of bonding processes.

Three-axis MEMS inertial sensor for automobile applications

A three-axis microelectromechanical systems (MEMS) inertial sensor measuring two-axis acceleration and angular rate (rotation) has been developed for an electronic stability control (ESC) system for automobiles. We combined the angular rate detection part with the two-axis acceleration detection parts on a single MEMS chip to miniaturize the sensor. The two detection parts were designed to work under different environmental pressures through a two-step wafer level package (WLP) process to achieve the required sensitivity for the gyroscope with excellent vibration immunity for the accelerometers. We report on the design concept and test results of the three-axis MEMS inertial combined sensor and the manufacturing processes of the two-step WLP and through-silicon vias (TSVs).

Deformation-robust gyroscope with 2.0-Hz frequency split variation over temperature range of −50 to 150°c

A micromachined deformation-robust gyroscope with only a 2.0-Hz frequency split variation over the temperature range for automobile applications was developed. Our design, which is a triangularly supported one-sided open frame with three sets of symmetrically arranged folded beams, dissipates and cancels the internal stress of springs caused by deformation. This suppresses the frequency variation between drive mode and sense mode (frequency split) over a wide range of temperatures. Experimental results showed that the proposed gyroscope has only a 2.0-Hz frequency split variation, which brings less than a 1% scale-factor change and an offset change that is 1.5% of the quadrature error.

Out-of-plane axis SOI MEMS gyroscope with initially displaced vertical sensing comb

We developed a capacitive silicon on insulator (SOI) microelectro-mechanical systems (MEMS) tuning-fork gyroscope and describe its structure and performance.