Metal Surface Chemical Composition and Morphology

Abstract

Metallization is one of the critical steps in microelectronic fabrication industries in which metals undergo various processing techniques such as deposition, polishing, and cleaning. Metals may undesirably diffuse into active device regions or corrode during various stages of processing, thus passivation of these metal surfaces is strongly recommended. The selection of a suitable passivating agent is necessary, especially during the polishing and cleaning processes to control contamination issues that may occur on the metal surface. This chapter is divided into four main sections for the four key metals found in semiconductor manufacturing: aluminum, copper, tungsten, and cobalt. Because the passivation process during polishing and cleaning is strongly influenced by the surface morphology, the microstructure and texture of as-deposited metals obtained with various deposition techniques are discussed. Then, the passivation process using wet chemistry and the resulting surface chemistry of passivated surfaces are presented. Finally, the different contamination issues of passivated metals and the cleaning processes employed to overcome the contamination are outlined. © 2018 Elsevier Inc. All rights reserved.