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A novel and reliable approach for controlling silicon membrane thickness with smooth surface

DOI: 10.1016/j.mee.2021.111640 DOI Help

Authors: Yijie Li (Fudan University) , Yifang Chen (Fudan University) , Hongchang Wang (Diamond Light Source) , Xujie Tong (Fudan University) , Chengyang Mu (Fudan University) , Jun Zhao (Fudan University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Microelectronic Engineering , VOL 3

State: Published (Approved)
Published: October 2021

Abstract: Despite self-supporting ultrathin Si membranes are already being widely applied, its thickness control in micron scale still remains a big challenge for delicate systems such as micro-opto-electro-mechanical systems and silicon-based X-ray diffractive optics. Instead of using the conventional wet etch rate of Si to monitor the membrane thickness, this work has developed a reliable approach to control the membrane thickness in the precision of micrometer order by using an optical detection hole with high precision depth, which decides the membrane thickness in the Si thinning process. The wet etch rate is first optimized to ensure the fundamental condition for such a thickness control. Furthermore, the membrane surface roughness is greatly reduced by optimizing the additive ethanol concentration in the KOH etchant, based on the investigation results for the origin of the membrane surface roughness. Using the proposed etching and thickness-monitoring method, self-supporting micron thick Si (100) membranes with the surface roughness of <15 nm have been successfully fabricated.

Journal Keywords: Free-standing Si membranes; Nanofabrication; Membrane thickness control; Detection hole method; X-ray components

Subject Areas: Physics, Engineering

Technical Areas:

Added On: 13/10/2021 10:06

Discipline Tags:

Surfaces Physics interfaces and thin films Engineering & Technology

Technical Tags: