Diagnostic of graphene on Ge(100)/Si(100) in a 200 mm wafer Si technology environment by spectroscopic ellipsometry/reflectometry

• Published in: Journal of vacuum science and technology. B, Nanotechnology & microelectronics Nanotechnology & microelectronics, 2019-11, Vol.37 (6)
• Main Authors: Fursenko, Oksana, Lukosius, Mindaugas, Bauer, Joachim, Villringer, Claus, Lux, Helge, Bärwolf, Florian, Lisker, Marco, Mai, Andreas
• Format: Article
• Language: English
• ISSN: 2166-2746; 2166-2754
• DOI: 10.1116/1.5122792

Comprehensive diagnostics is a prerequisite for the application of graphene in semiconductor technologies. Here, the authors present long-term investigations of graphene on 200-mm Ge(100)/Si(100) wafers under clean room environmental conditions. Diagnostic of graphene was performed by a fast and nondestructive metrology method based on the combination of spectroscopic ellipsometry and reflectometry (SE/R), realized within a wafer optical metrology tool. A robust procedure for unambiguous thickness monitoring of a multilayer film stack, including graphene, interface layer GeOx underneath graphene, and surface roughness is developed and applied for process control. The authors found a relationship between the quality of graphene and the growth of GeOx beneath graphene. Enhanced oxidation of Ge beneath graphene was registered as a long-term process. SE/R measurements were validated and complemented using atomic force microscopy, scanning electron microscopy, Raman spectroscopy, and secondary ion mass spectrometry. This comparative study shows a high potential for optical metrology of graphene deposited on Ge/Si structures, due to its great sensitivity, repeatability, and flexibility, realized in a nondestructive way.