Handbook of Cleaning for Semiconductor Manufacturing: Fundamentals and Applications

Chapter 1

Surface and Colloidal Chemical Aspects of Wet Cleaning

Srini Raghavan, Manish Keswani, and Nandini Venkataraman

Department of Materials Science & Engineering The University of Arizona Tucson, Arizona, USA

Abstract

Surface and colloidal chemicals aspects relevant to wet chemical cleaning and drying of semiconductor surfaces are reviewed. Specific areas discussed in this chapter include surface charging of metal oxide and nitride films, development of an electrical double layer, zeta potential of electrified interfaces and its effect on particulate contamination, adsorption of surfactants and metal ions on insulating surfaces, principles of surface tension gradient drying, and wetting and penetration of high aspect ratio features.

Key words: interfacial phenomena, wet cleaning, surface charging of metal oxide and nitride, electrical double layer, metal adsorption, high aspect ratio cleaning, surface tension gradient drying

1.1 Introduction to Surface Chemical Aspects of Cleaning

The fabrication of integrated circuits requires a myriad of liquid-based etching and cleaning processes that are followed by rinsing and drying steps. Interfacial phenomena such as wetting, spreading, adsorption, adhesion, and surface charge play a critical role in determining the feasibility and efficiency of a liquid-based process step. The objective of this chapter is to discuss the fundamental science of the key interfacial phenomena relevant to wafer etching, cleaning, and drying. Specific ...