CEA-LETI-Minatec, 17 rue des martyrs, Grenoble Cedex 09, France, ST Microelectronics, 850 rue Jean Monnet, Crolles, France

Silicon nitride spacer etching is one of the most critical step for the fabrication of CMOS transistors in microelectronics. It is usually done by plasma etching using a fluorocarbon based chemistry. However, from the 14 nm technology node and beyond, this etching process no longer allows the etch specifications to be reached (nonformation of a foot, poor critical dimension control below 1 nm). To overcome this issue, a new process was developed. It consists of two steps: in a first step, the silicon nitride film is modified by light ion implantation (hydrogen), and then followed by a removal step of this modified film by hydrofluoric acid (HF). In this paper, the authors propose to remove the implanted/modified silicon nitride using gaseous HF and understand the associated etching mechanisms using infrared spectroscopy and x-ray photoelectron spectroscopy at different stages of the process sequence (after implantation/modification, gaseous HF process, and post-treatment). © 2017 American Vacuum Society.

Hydrofluoric acid, Infrared spectroscopy, Ion implantation, Microelectronics, Nitrides, Plasma etching, Silicon, Silicon nitride, CMOS transistors, Critical dimension control, Different stages, Etching mechanism, Hydrogen ion implantation, Light ion implantation, Silicon Nitride Film, Technology nodes, X ray photoelectron spectroscopy