A Review and Unifying Analysis of Defect Decoration and Surface Polishing by Chemical Etching in Silicon Processing

• Published in: Industrial & engineering chemistry research Vol. 42; no. 12; pp. 2558 - 2588
• Main Author: Kulkarni, Milind S
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 11.06.2003
• Subjects: Applied sciences; Electronics; Exact sciences and technology; Microelectronic fabrication (materials and surfaces technology); Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie020716y

A comprehensive review of dynamics of etching and its various applications in silicon wafer processing is accomplished, and new developments are discussed. A previously proposed pseudo two-phase phenomenological model to describe the dynamics of three-phase etching is revisited and novel augmentations are proposed. Interplay between the liquid-phase transport of reagents, the silicon surface kinetics, and the formation and the transport of gaseous bubbles is quantified. Both the model and the reported data explain effects of etching on silicon-surface polishing. Recent attempts to extend the pseudo two-phase model to describe the defect decoration by acid-based etching are discussed and new modifications are proposed. Microdefect (agglomerated defect) distribution in a monocrystalline silicon wafer is identified by growing copper precipitates on the microdefects followed by surface polishing and subsequent microdefect-decorating etching, which forms the pits on the wafer known as etch-pits by a relatively rapid chemical dissolution of the precipitates. The macrodecoration of microdefects is typically realized in the absence of significant effects of the liquid-phase mass-transport. The developed phenomenological model leads to classification of etchants as either polishing or potentially decorating and to the identification of conditions necessary for an efficient microdefect decoration. The reported analytical expressions for the microdefect-decorating and the microdefect-polishing conditions are also revisited, revised, and augmented. A series of reported experiments validates the developed model.