Self-Controlled Cleaving Method for Silicon DRIE Process Cross-Section Characterization.

Area of Science:

• Materials Science
• Mechanical Engineering
• Nanotechnology

Background:

• High-aspect silicon microstructures are crucial for advanced microsystems like optoelectronics and lab-on-chips.
• The Bosch process is a standard for fabricating these microstructures in micro-electro-mechanical systems (MEMS).
• Accurate characterization of the Bosch process relies on cross-section metrology, typically achieved by cleaving.

Purpose of the Study:

• To develop a highly controllable cross-section cleaving method for deep silicon microstructures.
• To minimize the impact of cleaving on the etched profile, ensuring metrology quality.
• To identify and mitigate defects caused by cleaving in high-aspect ratio structures.

Main Methods:

• Experimental comparison of two cleaving methods using auxiliary microstructures: transverse lines and dashed lines.
• Analysis of the interplay between auxiliary line parameters and the Bosch etching process.
• Investigation of dense periodic and isolated trenches with aspect ratios > 10.

Main Results:

• Standard cleaving with diamond scribers is insufficient for deep, neighboring microstructures.
• Incorrect auxiliary line parameters can cause silicon 'build-up' defects, compromising metrology.
• A defect-free cleaving method using dashed auxiliary lines with stress concentrators was successfully demonstrated.

Conclusions:

• A novel, controllable cleaving method using dashed auxiliary lines is proposed for accurate cross-section metrology of Bosch-etched MEMS.
• This method effectively prevents defects and preserves the integrity of high-aspect ratio silicon microstructures.
• The findings are critical for reliable quality control in MEMS mass production.