MEMS Sensor Side Port Fluid Access
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Solution Overview
Problem
Current MEMS sensor packaging faces challenges in achieving smaller size and low cost without compromising performance, particularly in interacting with external environments and requiring robust mechanical and environmental protection while allowing for fluid interaction.
Innovation Solution
A MEMS sensor package design featuring a substrate with a MEMS sensor under a cap layer, where a side wall port is exposed during singulation, allowing external fluid to enter the cavity and enabling ambient pressure detection without obstructing the port with encapsulant, and utilizing cantilevered platform structures for stress isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a top vent hole is used in conventional packages, then fluid can enter the cavity, but the encapsulant must be thinned or opened to avoid obstructing the port
Solution Approach 1:
The patent transitions from a vertical port configuration (top vent hole through the encapsulant) to a lateral port configuration (side wall port in the substrate). This dimensional change allows the port to be formed in the substrate's side wall rather than requiring the encapsulant to be thinned or opened from the top, thereby maintaining a fully sealed encapsulant structure while enabling fluid access to the cavity.
2Ease of manufacture
If package size is reduced to meet cost targets, then manufacturing cost decreases, but maintaining performance and robustness becomes more difficult
Solution Approach 1:
The patent integrates the port formation into the substrate manufacturing process itself, rather than requiring separate post-processing steps. The port is formed as part of the substrate structure using standard semiconductor fabrication techniques, which merges the port creation step with the existing substrate manufacturing flow. This integration reduces additional manufacturing complexity and cost while maintaining reliable fluid access.
Solution Approach 2:
The substrate structure itself provides the port function through its own geometry, eliminating the need for separate port formation steps in the encapsulant. The side wall port is inherently part of the substrate design, allowing the substrate to serve dual purposes: structural support and fluid access pathway.
3Reliability
If encapsulant is thinned or opened to accommodate top vent hole, then fluid can enter cavity, but mechanical protection and sealing are compromised
Solution Approach 1:
The patent moves the port location from the vertical dimension (through the encapsulant thickness) to the lateral dimension (in the substrate's side wall). This allows the encapsulant to maintain its full thickness and sealing integrity while the substrate's side wall provides the fluid access pathway, thus preserving mechanical strength and protection.
Solution Approach 2:
The substrate acts as an intermediary structure that provides fluid access without requiring modifications to the encapsulant. Instead of modifying the encapsulant to create a port, the substrate's side wall port serves as the interface between the external environment and the internal cavity, allowing the encapsulant to remain intact and provide full mechanical protection.
Data Source
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AI summary
A MEMS sensor package comprises a MEMS die that includes a substrate having a sensor formed thereon and a cap layer coupled to the substrate. The cap layer has a cavity overlying a substrate region at which the sensor resides. A port extends between the cavity and a side wall of the MEMS die and enables admittance of fluid into the cavity. Fabrication methodology entails providing a substrate structure having sensors formed thereon, providing a cap layer structure having inwardly extending cavities, and forming a channel between pairs of the cavities. The cap layer structure is coupled with the substrate structure and each channel is interposed between a pair of cavities. A singulation process produces a pair of sensor packages, each having a port formed by splitting the channel, where the port is exposed during singulation and extends between its respective cavity and side wall of the sensor package.