Reactive Ion Etching (RIE) is a process used in semiconductor manufacturing to etch precise patterns onto materials. It combines physical bombardment from ions with chemical reactions from reactive gases, allowing for high-resolution patterning on surfaces. This technique is essential for creating intricate designs in microelectronics and nanotechnology. During RIE, a gas is introduced into a vacuum chamber, where it is ionized by an electric field. The ions then collide with the material's surface, removing atoms and creating the desired pattern. RIE is widely used in the fabrication of devices like integrated circuits and microelectromechanical systems (MEMS).