Optical lithography—a historical perspective

Optical lithography (also called photolithography) has been the key enabler for scaling feature sizes of integrated circuits, allowing the exponential growth of the semiconductor industry. Often in the past the end of optical lithography has been predicted but this technology is, and is expected to stay, mainstream for the next several years. This article will describe the breakthroughs which allowed photolithography fulfilling all the requirements of advanced volume manufacturing. Based on few principles of optics, this technology went through significant evolutions in the exposure tool and in the photoresist, in reducing the exposure wavelength and more recently by taking advantage of the light coherence and correcting proximity effects, esp. through advanced mask design and optimized illumination techniques. Finally this article will discuss some recent trends in photolithography. To cite this article: K. Ronse, C. R. Physique 7 (2006).