microfabrication

Microfabrication refers to the set of processes used to construct structures with micron-scale, and often sub-micron, features. It is a foundational discipline in the production of integrated circuits, microelectromechanical systems (MEMS), optical devices, and microfluidic components, where precise patterning and material control are essential.

The core techniques include lithography to pattern materials, deposition to add layers, etching to remove material, and doping to tailor electrical properties. Planarization, typically by chemical-mechanical polishing (CMP), creates flat surfaces for subsequent layers. A typical flow starts with a wafer, followed by layers, patterning, etching, and interconnect formation.

Materials commonly used include silicon and silicon dioxide on silicon wafers, silicon nitride, glasses and polymers, and metals such as aluminum and copper for interconnects. Substrates and films are chosen to meet electrical, optical, thermal, and mechanical requirements of the target device.

Equipment is housed in cleanroom environments to limit contamination. Key tools include photolithography systems, dry etchers such as reactive ion etchers (RIE) or deep reactive ion etchers (DRIE), deposition systems (chemical vapor deposition, physical vapor deposition, and atomic layer deposition), ion implanters, and CMP machinery. Process control emphasizes defect reduction, uniformity, coverage, and tight dimensional tolerances.

Applications span semiconductor devices and integrated circuits, MEMS such as accelerometers and pressure sensors, microfluidic chips for biological analysis, and optical components. The field continually progresses toward smaller feature sizes and three-dimensional integration, balancing speed, power, yield, and manufacturing cost.

Microfabrication emerged from semiconductor manufacturing in the mid-20th century and has since evolved with new lithography techniques, deposition methods, and etching chemistries to enable modern nanometer-scale devices.