Metrology for Device Fabrication
Semiconductor metrology is the science of measurement, such as dimensions, film thickness, dielectric constant, resistivity and chemical composition. It is a vast area of science separate from device fabrication; yet, it is intimately related to every nanofabrication process step. Semiconductor metrology can be widely categorized into device fabrication metrology and interconnect metrology. Metal oxide semiconductor transistors are at the core of all device fabrication processes. Transistors are built by selectively doping the substrate with donors and acceptors to create n- and p-type regions. An important difference between Secondary ion mass spectroscopy (SIMS) and spreading resistance profiling (SRP) is that SIMS measures the raw atomic concentration of the dopants, while SRP measures the activated dopant concentration. The dielectric film is characterized using ellipsometry and reflectometry. The latter is a simpler technique than ellipsometry because it uses normal incidence beams.