A processing tool used to transfer lithographic patterns from a photomask to a silicon wafer.
Four types of aligners are in use within Harris: contact, proximity, projection, and steppers. Contact aligners were the earliest type, and have the disadvantage of bringing the photomask in direct contact with the wafer, thereby inviting particulate contamination. The other types avoid direct mask contact and bring increasing line-width control and resolution.
See also lithography, mask and stepper. (출처 : 세미파크)