MEMS Sensor Fluidic Path Through Support Structure
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Solution Overview
Problem
Existing MEMS pressure sensors face challenges in manufacturing complexity due to the need for a hole in the cap for fluidic path formation, which complicates packaging and membrane thickness control, especially when detecting absolute pressures.
Innovation Solution
A MEMS device with a fluidic path extending through a support and die, connecting the membrane to the outside, eliminating the need for a front hole in the cap and simplifying the manufacturing process by using adhesive regions and a cap fixed to the die, allowing standard molding and reducing assembly stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a hole is formed in the cap for fluidic path, then fluid communication is achieved, but manufacturing complexity increases and molding becomes difficult
Solution Approach 1:
The fluidic path is extracted from the cap structure and relocated to the support structure. The support now incorporates the through-hole for fluid communication, eliminating the need for complex cap molding with integrated holes. This separation of functions simplifies cap manufacturing while maintaining fluidic connectivity.
Solution Approach 2:
The fluidic path is repositioned from a vertical hole in the cap to a horizontal/angled path through the support structure. This dimensional relocation allows standard cap molding processes to be used while achieving fluid communication through an alternative structural route via the support.
2Manufacturing precision
If membrane thickness is controlled through deep etching from the back, then membrane formation is achieved, but thickness control becomes complex
Solution Approach 1:
Instead of forming the membrane by deep etching from the back of the substrate, the approach is inverted to form the membrane by etching from the front surface. This reversal of the etching direction simplifies thickness control and membrane formation while achieving the same functional result.
3Reliability
If the cap is molded flush to prevent hole occlusion, then packaging integrity is improved, but molding complexity increases
Solution Approach 1:
The fluidic hole function is extracted from the cap and assigned to the support structure. This allows the cap to be molded as a simple, flush structure without complex hole-forming operations, while the support structure provides the necessary fluidic pathway, maintaining both reliability and manufacturing simplicity.
Data Source
AI summary
A MEMS device wherein a die of semiconductor material has a first face and a second face. A membrane is formed in or on the die and faces the first surface. A cap is fixed to the first face of the first die and is spaced apart from the membrane by a space. The die is fixed, on its second face, to an ASIC, which integrates a circuit for processing the signals generated by the die. The ASIC is in turn fixed on a support. A packaging region coats the die, the cap, and the ASIC and seals them from the outside environment. A fluidic path is formed through the support, the ASIC, and the first die, and connects the membrane and the first face of the die with the outside, without requiring holes in the cap.