TABLE OF CONTENTS Sensors convert information about the environment, such as temperature, pressure, force, or acceleration, etc., into an electrical signal. With the development of microelectronics technology with silicon as the base material in the 1970s, sensors using the properties of silicon entered the component market. Silicon's physical properties make it an ideal building material for mechanical devices. Silicon has the hardness of steel, the thermal conductivity of diamond, piezoresistive properties, a light weight, and low thermal expansion; also it is relatively inert. It is free of hysteresis and its crystalline structure is well suited to the fabrication of miniature precision products. Silicon micromechanical products have several advantages over their conventionally manufactured counterparts. They are generally much smaller. Their performance is higher because of the precise dimensional control in the fabrication and costs are lower owing to the possibility of mass scale production.
Silicon micromachining is a powerful outgrowth of semiconductor process technology whereby integrated circuit manufacturing techniques are supplemented by the silicon etching process to create very precise, miniature micromechanical structures. These silicon microstructures can have electronic features that allow conversion of physical input into electrical signals. Similarly, electrical signals can be applied to these devices to provide control functions. Initially developed in the 1950s and 1960s at leading semiconductor pioneers including Fairchild and National Semiconductor, the technology was further advanced in the 1970s at universities throughout the world. Commercial activities picked up in the early 1980s with a number of start-ups located in the Silicon Valley area of the...
