Microsensors vs. integrated circuits: a study in contrasts

The author examines the contrasts between conventional IC design paradigms and the corresponding paradigms for microsensors in four areas: system partitioning, technology constraints, packaging constraints, and CAD (computer-aided design) requirements. It is found that many of the driving forces for smaller feature sizes, higher levels of integration, higher I/O count, and standardized packages and process sequences in the IC domain have corresponding driving forces in the microsensor domain, but often with opposite direction: maintain larger feature sizes for dimensional precision, keep the level of integration and I/O count minimal, and assume that process technologies and packages may be application specific. In the CAD area, there are many similarities, but the need in the microsensor domain for mechanical performance prediction requires two CAD capabilities: the ability to predict mechanical properties and residual stresses from a description of the process sequence and the ability to construct a 3-D solid model of the fabricated device in a format suitable for mechanical analysis with finite-element-method codes.<>