(Invited) Unit Steps of an ALD Half-Cycle

Abstract

ALD is based on exposing the substrate sequentially to selflimiting surface reactions with two or more reactants. The elemental step of the ALD deposition method is called the halfcycle, i.e. the pulse and purge step of one precursor. While in the open literature, the ALD deposition has vigorously been studied from the surface chemistry point of view, the fundamental unit steps from an engineering point of view are much less studied subjects. In this paper, the unit steps that an ALD reactor has to perform in order to approach the ideal ALD half-cycle, namely a square wave partial pressure pulse followed by perfect purging of the reactor are discussed.