3-DIMENSIONAL VECTOR ACCELEROMETER USING SOI STRUCTURE FOR HIGH-TEMPERATURE USE

In order to improve the high-temperature reliability of a silicon acce lerometer, an accelerometer was fabricated using an SOI substrate and its temperature dependence was compared with that of conventional sili con accelerometers. In addition, the authors attempted to detect the t hree-dimensional components of the acceleration vector using a new the oretical principle. The new theoretical principle was validated, and a ccelerometer design was carried out using a program for structure anal ysis, ANSYS, which is based on the finite element method (FEM). It was found that, in the accelerometer fabricated using an SOI substrate, t he offset voltage and sensitivity at temperatures higher than 200 degr ees C were superior to those in the conventional pn junction device. I t was also found that the new device could detect acceleration even at 410 degrees C. Using the new device, the acceleration components in t he three directions were accurately measured and the sensitivity for t he other axis was suppressed to less than 5.7 percent. The frequency c haracteristic of the new sensor was in agreement with the theoretical results. Because of high-temperature operation and detectability of th e three directional components of acceleration, this new accelerometer will be much more widely used.