TABLE OF CONTENTS As with micromachining processes, many MEMS sensor-packaging techniques are the same as, or derived from, those used in the semiconductor industry. However, the mechanical requirements for a sensor package are typically much more stringent than for purely microelectronic devices. Microelectronic packages are often generic with plastic, ceramic, or metal packages being suitable for the vast majority of IC applications. For example, small stresses and strains transmitted to a microelectronics die will be tolerable as long as they stay within acceptable limits and do not affect reliability. In the case of a MEMS physical sensor, however, such stresses and strains and other undesirable influences must be carefully controlled in order for the device to function correctly. Failure to do so, even when employing electronic compensation techniques, will reduce both the sensor performance and long-term stability.
The need to control such external stresses is complicated by the simple fact that all MEMS sensors designed for physical sensing applications have to interact with their environment in order to function. The physical measurand must therefore be coupled to the sensor in a controlled manor that excludes, where possible, other undesirable influences and cross-sensitivities. In order to achieve this, the design of the sensor packaging is as important as the design of the sensor itself. The sensor packaging has a major influence on the performance of the device, especially with respect to factors such as long-term drift and stability. It is very important that the packaging of the sensor is considered at the...
