Self-removal Anti-stiction Coating for MEMS Bonding
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Solution Overview
Problem
Existing anti-stiction layers in MEMS devices hinder effective bonding during wafer level packaging due to their inability to be selectively removed without additional costly processing steps like UV treatment.
Innovation Solution
A method involving a eutectic reaction between a bonding layer and an interlayer forms a liquid phase, causing the anti-stiction layer to float and self-align out of the bonding area, allowing for direct bonding between layers without the need for UV treatment, using conductive materials like Al and Ge to create a eutectic alloy layer that facilitates the removal of the anti-stiction layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anti-stiction layers are used to prevent stiction in MEMS devices, then adhesion protection is improved, but bonding effectiveness deteriorates
Solution Approach 1:
The bonding layer is segmented into multiple functional layers including a first bonding layer with the anti-stiction layer, an interlayer, and a second bonding layer. This segmentation allows the anti-stiction layer to remain on the first bonding layer while the second bonding layer bonds to the interlayer, resolving the contradiction between adhesion protection and bonding effectiveness
Solution Approach 2:
An interlayer is introduced as an intermediary between the first bonding layer (with anti-stiction layer) and the second bonding layer. This interlayer acts as a mediator that enables bonding to occur without requiring direct contact with the anti-stiction layer, thus maintaining both adhesion protection and bonding effectiveness
2Ease of manufacture
If UV treatment is used to remove anti-stiction layer from bonding areas, then bonding effectiveness is improved, but fabrication complexity increases
Solution Approach 1:
The bonding structure is preliminarily designed with multiple layers (first bonding layer, interlayer, second bonding layer) during the fabrication process itself, rather than requiring subsequent UV treatment. This preliminary structural arrangement enables effective bonding without adding post-fabrication processing steps
Solution Approach 2:
The anti-stiction layer is extracted from the bonding interface by placing it only on the first bonding layer, while the actual bonding occurs between the second bonding layer and the interlayer. This extraction eliminates the need for UV treatment to remove the anti-stiction layer from bonding areas
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
This method enables self-aligned anti-stiction layer removal and improved bonding in MEMS devices, reducing fabrication costs and processing complexity by integrating anti-stiction layer removal into the packaging process, specifically in wafer level packaging technology.
Implementation Method 1
a eutectic reaction between a bonding layer and an interlayer to form a liquid phase
Data Source
AI summary
The present disclosure provides a device having a doped active region disposed in a substrate. The doped active region having an elongate shape and extends in a first direction. The device also includes a plurality of first metal gates disposed over the active region such that the first metal gates each extend in a second direction different from the first direction. The plurality of first metal gates includes an outer-most first metal gate having a greater dimension measured in the second direction than the rest of the first metal gates. The device further includes a plurality of second metal gates disposed over the substrate but not over the doped active region. The second metal gates contain different materials than the first metal gates. The second metal gates each extend in the second direction and form a plurality of respective N/P boundaries with the first metal gates.