Reduced Etch Lag and High Aspect Ratios by Deep Reactive Ion Etching (DRIE)
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Date
2021-05
Publication Type
Journal Article
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yes
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Abstract
Deep reactive ion etching (DRIE) with the Bosch process is one of the key procedures used to manufacture micron-sized structures for MEMS and microfluidic applications in silicon and, hence, of increasing importance for miniaturisation in biomedical research. While guaranteeing high aspect ratio structures and providing high design flexibility, the etching procedure suffers from reactive ion etching lag and often relies on complex oxide masks to enable deep etching. The reactive ion etching lag, leading to reduced etch depths for features exceeding an aspect ratio of 1:1, typically causes a height difference of above 10% for structures with aspect ratios ranging from 2.5:1 to 10:1, and, therefore, can significantly influence subsequent device functionality. In this work, we introduce an optimised two-step Bosch process that reduces the etch lag to below 1.5%. Furthermore, we demonstrate an improved three-step Bosch process, allowing the fabrication of structures with 6 µm width at depths up to 180 µm while maintaining their stability.
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published
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Book title
Journal / series
Volume
12 (5)
Pages / Article No.
542
Publisher
MDPI
Event
Edition / version
Methods
Software
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Date collected
Date created
Subject
fabrication; deep reactive ion etching; process optimization; reduced etch lag; high aspect ratio; small structures
Organisational unit
03307 - Dual, Jürg (emeritus) / Dual, Jürg (emeritus)
03627 - Nelson, Bradley J. / Nelson, Bradley J.
02205 - FIRST-Lab / FIRST Center for Micro- and Nanoscience
Notes
Funding
SNF_166110 - Mechanical Basis for the Convergent Evolution of Sensory Hairs in Animals and Plants (SNF)