Photolithography

Synonyms

Optical lithography

Definition

Photolithography is a process used in microfabrication to selectively pattern a thin film substrate using light to transfer a geometric pattern from a photomask to a light-sensitive photoresist.

Introduction

Lithography is a technique used to transfer copies of a master pattern onto the surface of a solid material such as a silicon wafer. The word lithography (Greek for the words stone [lithos] and to write [gráphein]) refers to the process invented in 1796 by Aloys Senefelder, who inked Bavarian limestone and transferred a carved image from stone onto paper. The most widely used form of lithography is photolithography. In the IC industry, pattern transfer from masks onto thin films is accomplished almost exclusively via photolithography. Photomasking, followed by chemical processing, led to the photolithography now used in fabricating ICs (integrated circuits) and in miniaturization science. The first applications of the printed circuit board...