MEMS Gap Etching Layout to Prevent DRIE Sidewall Damage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Deep-reactive ion etching (DRIE) processes often cause structural damage and measurement errors in MEMS devices due to load effects on sidewalls when etching narrow and wide gaps simultaneously.
Innovation Solution
A method involving the use of a temporary structure in broader gaps, etching temporary gaps with the same width as narrow gaps, and then removing the temporary structure to prevent DRIE load effects on sidewalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If narrow and wide gaps are etched simultaneously in the same DRIE process, then manufacturing efficiency is improved, but sidewalls of broad gaps suffer from DRIE load effects causing structural damage
Solution Approach 1:
The broad gap etching process is segmented into two stages: first etching temporary narrow gaps on both sides of the broad gap region, then etching the central broad gap region. This segmentation allows each etched region to have appropriate width for minimizing DRIE load effects, preventing sidewall damage while maintaining manufacturing efficiency.
Solution Approach 2:
Temporary structures are deposited in advance in the broad gap regions before the final etching step. These temporary structures serve as placeholders that define the boundaries of the broad gap and enable the creation of temporary narrow gaps during the first etching stage, thereby preventing DRIE load effects on the final broad gap sidewalls.
2Manufacturing precision
If temporary structures are added to prevent DRIE load effects, then sidewall structural integrity is improved, but device complexity increases
Solution Approach 1:
Temporary structures are deposited and then completely removed after serving their purpose of defining the broad gap region during etching. These temporary structures are discarded after the etching process, leaving no residual complexity in the final device while having successfully prevented DRIE load effects during manufacturing.
Solution Approach 2:
The temporary structures are extracted from the final device design - they are only present during the manufacturing process and are completely removed afterward. This extraction approach allows the use of complex temporary structures to solve the DRIE load effect problem without permanently increasing device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents structural damage to sidewalls of broader gaps by equalizing DRIE load on both narrow and broader gaps, ensuring accurate and reliable MEMS device operation.
Implementation Method 1
Deep-reactive ion etching (DRIE) is a common method for etching gaps and trenches in silicon wafers
Data Source
Figure 1~2b
Figure 2c~2e
Figure 2f~3a
AI summary
A method for manufacturing a micromechanical structure in the structural layer of a wafer by forming a first gap and a second gap depositing and patterning a first etching mask and a second etching mask on a horizontal face of the structural layer, etching trenches through the structural layer in the first and second unprotected areas which are not protected by the first etching mask or the second etching mask, coating at least the sidewalls of the trenches with a protective layer and removing the second etching mask at least from a second opening in the first etching mask, so that a temporarily protected area is exposed, and etching away the structural layer in the exposed temporarily protected area.