MEMS Etch Stop Layer for Controlled Sacrificial Release
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Solution Overview
Problem
Current wafer level packaging technologies face challenges such as incompatibility with device fabrication processes, area/density penalties, contamination issues, and structural weaknesses, particularly in MEMS devices due to poor control over the etch of sacrificial layers.
Innovation Solution
A MEMS device fabrication method involving a substrate with a dielectric layer, an etch stop layer, and anchor plugs that contact the etch stop layer or a top metal layer, allowing for controlled removal of a sacrificial layer through a release aperture, enhancing mechanical strength and integration with CMOS processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wafer level packaging technology is used to package MEMS devices, then packaging efficiency is improved, but mechanical strength at anchor area deteriorates due to poor control over etch of sacrificial layer
Solution Approach 1:
An etch stop layer is formed above the dielectric layer before forming the sacrificial layer. This preliminary action enables precise control over the etching process that will later remove the sacrificial layer, thereby preventing uncontrolled etch damage to the anchor area and improving mechanical strength while maintaining packaging efficiency
Solution Approach 2:
The etch stop layer acts as an intermediary between the dielectric layer and the sacrificial layer. It mediates the etching process by providing a controlled stopping point, preventing the etchant from damaging the anchor area while allowing complete removal of the sacrificial layer, thus resolving the contradiction between packaging efficiency and mechanical strength
2Ease of manufacture
If current packaging methods are used, then packaging is achieved, but structural weakness occurs due to lack of control over etch of sacrificial layer
Solution Approach 1:
The etch stop layer is formed in advance as a preliminary measure to control the subsequent sacrificial layer removal process. This preliminary structure prevents structural weakness by ensuring controlled etching, while adding minimal complexity to the overall packaging process
Solution Approach 2:
The etch stop layer changes the etching parameters by providing a distinct stopping point for the etchant. This parameter change enables precise control over the sacrificial layer removal, preventing over-etching and structural damage while maintaining process simplicity
3Productivity
If sacrificial layer etch is not controlled, then packaging can be completed, but contamination issues and structural weakness occur
Solution Approach 1:
The etch stop layer serves as an intermediary that controls the etching process, preventing uncontrolled etch propagation that would cause contamination and structural weakness. It allows the packaging process to complete quickly while preventing harmful effects through precise etch termination
Data Source
AI summary
The present disclosure provides a micro-electro-mechanical systems (MEMS) device and a method for fabricating such a device. In an embodiment, a MEMS device includes a substrate, a dielectric layer above the substrate, an etch stop layer above the dielectric layer, and two anchor plugs above the dielectric layer, the two anchor plugs each contacting the etch stop layer or a top metal layer disposed above the dielectric layer. The device further comprises a MEMS structure layer disposed above a cavity formed between the two anchor plugs and above the etch stop layer from release of a sacrificial layer.