that represent large markets for optical systems and devices. An illustrative selection of other applications with significant potential for growth is also given.

This chapter is organized in five sections. Two explore the use of light to perform manufacturing and the use of optics to control manufacturing, respectively. Industry-by-industry examples follow to highlight the interplay between the various applications of optics to perform manufacturing in each industry. Prospects for increasing the use of optics in manufacturing are discussed in the next section. Findings, conclusions, and recommendations are gathered in the last section.

Use of Light to Perform Manufacturing

Because of the many unique properties of light and the manner in which light interacts with matter, optics offers a rich variety of application options for manufacturing processes. The imaging properties of light and its ability to induce photochemical reactions allow highly complex mask patterns to be transferred to photoresist in the optical lithography process. Tightly focused laser beams can deliver thermal energy to the workpiece for cutting, welding, or drilling with a precision and accuracy unmatched by any other technique; they can also induce localized photochemical reactions to generate solid three-dimensional prototype parts. Additional advantages are the ability to deliver this energy at a distance in a noncontact manner through windows and in various atmospheres. Some of light's diverse range of utility is illustrated in the following applications.

Photolithography

Photolithography plays an essential enabling role in integrated circuit processing. Photolithography requires both an optical system—the step-and-repeat camera (stepper) that is the workhorse of the integrated circuit (IC) industry—and an optical material—the light-sensitive photoresist used to transfer the desired pattern to the silicon substrate or thin film of interest (Figure 5.1). As the demand for faster processing speeds continues, increasing pressure will be put on photolithographic processes to produce smaller feature dimensions, requiring new photolithographic tools, new materials, shorter wavelength light sources, and other more advanced optical system designs.

At present, photolithography requires the use of three elements:

  1. The mask, which defines which areas of the film to be patterned will be exposed to light;

  2. The exposure tool, which images the pattern from a mask onto the substrate; and



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