ALD: Atomic layer deposition - precise and conformal coating for better performance

Abstract

Atomic layer deposition (ALD) is a thin-film growth technology that is capable of depositing conformal, pinhole-free, and uniform films on high-aspect-ratio surfaces with atomic precision. It is similar to chemical vapor deposition (CVD), but compared to CVD, it usually produces thin films with better mechanical, thermal, and electrical properties. ALD is a rapidly growing field, and it is currently introduced in the semiconductor and solar cell industries. In this chapter, the basics of chemistry and mechanism of ALD process are firstly described. ALD is then compared with other coating processes, such as CVD, physical vapor deposition (PVD), and electroless plating, to present its distinct advantages and also limitation. The elements of ALD process such as precursors, thin-film material, and substrates are also individually discussed. The evolvement of the ALD reactors, including plasma-enhanced ALD and the latest high-throughput ALD designs, is introduced. A number of existing and potential future applications of the ALD process for industry are presented at the end of the chapter.