Thin film monitors are used to analyze and/or control thin film deposition rate, composition and properties.
Thin film monitors such as quartz crystal microbalances, ellipsometers or spectrometers for in-situ monitoring are used to control thin film deposition rates or composition during thin film processing. A thin film monitor can measure temperature, growth rate, and refractive index in molecular beam epitaxy (MBE) and metal-organic vapor phase deposition (MOCVD) processes. Two-wavelength reflectometry in normal or specular geometry allows thin film process monitors to measure the growth rate of thickness as low as 10 nm within a resolution better than 1 nm.
An ellipsometer measures the refractive index and the thickness of semi-transparent thin films. Thin film monitors such as ellipsometers can be used to measure layers as thin as 1 nm up to several microns thick. Ellipsometers are used to accurately determine the thicknesses of thin films, identify materials and thin layers, and characterize surfaces. An extremely sensitive mass sensor, a quartz crystal microbalance (QCM) device is capable of measuring mass changes in nanogram ranges. These types of thin film monitors are piezoelectric devices made of a thin plate of quartz with electrodes affixed to each side of a plate. Examples of QCM measurement instruments are quartz crystals, thin film deposition monitors, and thin film controllers.
A spectrometer is an instrument that measures the wavelength of electromagnetic radiation. When studying the planets, scientists use these types of thin film monitors to collect separate wavelengths of light. The light received from a planet is separated by means of a mirror or several mirrors, and then into separate wavelengths. In this way, spectrometers help scientists determine what makes up a planet. A reflectometer is a downward-facing pyranometer used to measure reflected solar radiation. Thin film monitors such as a reflectometer can be used to characterize the reflectance of ultra thin gate oxides and chemically amplified deep ultraviolet (UV) photo resist thin films. Reflection high-energy electron diffraction (RHEED) is a process in which electrons arrive at a grazing angle for an analyzed surface. This is similar to providing structural information as neutron diffraction.