Pressure Sensor Cover Layer Sealing and Strain Distribution
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Solution Overview
Problem
Existing methods for manufacturing pressure sensors with semiconductor chips and pressure-sensitive membranes are complex and lack a simple, efficient process for sealing and connecting the sensor to a housing, which affects the reliability and cost-effectiveness of the device.
Innovation Solution
A semiconductor chip with a topmost dielectric layer of silicon oxide and/or silicon nitride is processed to include a cover layer made of a different material, which forms a port for access to the membrane and is designed to provide a good sealing connection with a connecting member, allowing for a sealed connection and distribution of strain without increasing chip size, using common low-cost sealing techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cover layer is applied to provide a sealing connection with the connecting member, then the sealing reliability is improved, but the manufacturing complexity increases
Solution Approach 1:
The cover layer is integrated into the chip manufacturing process itself, forming the sealing surface during chip fabrication rather than adding a separate sealing component later. This preliminary action embeds the sealing function directly into the chip structure, improving reliability while avoiding additional manufacturing steps.
Solution Approach 2:
The cover layer combines multiple functions: it serves as both a structural element of the chip and as the sealing surface for the connecting member. By merging the sealing function with the chip's existing dielectric layers, the patent eliminates the need for separate sealing components and simplifies the overall manufacturing process.
2Reliability
If the cover layer is made softer to provide an improved seal, then the sealing quality is improved, but the mechanical strength decreases
Solution Approach 1:
The patent changes the material parameter of the cover layer by selecting softer materials such as silicon oxide or silicon nitride with appropriate elastic moduli. This parameter change allows the cover layer to deform and conform to the connecting member, creating a tight seal while maintaining sufficient structural integrity through the inherent properties of these materials.
Solution Approach 2:
The cover layer exhibits local quality differentiation where the material properties are optimized specifically for the sealing region. The softer material property is localized to where it is needed for sealing, while the overall chip structure maintains its mechanical strength through the underlying rigid substrate and support structures.
3Reliability
If the chip size is increased to provide a larger surface for sealing, then the sealing reliability is improved, but the manufacturing cost increases
Solution Approach 1:
Instead of increasing the lateral chip size to provide more sealing surface area, the patent utilizes the vertical dimension by creating a port structure that extends through the cover layer. This dimensional approach provides adequate sealing surface area within the existing chip footprint, avoiding increased manufacturing costs associated with larger chip sizes.
Solution Approach 2:
The cover layer functions as a flexible thin film that can conform to the connecting member geometry, providing effective sealing without requiring a large surface area. The thin film nature of the cover layer allows it to adapt to the connecting member shape, achieving reliable sealing within the constrained chip dimensions.
Data Source
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AI summary
A pressure sensor comprising a membrane (11) integrated on a semiconductor chip (1) is coated with a flexible, soft cover layer (24) forming two ports (20, 21) providing access to the opposite sides of the membrane (11). One port (20) is sealingly connected to a connecting member (28) of the housing (36) of the device, while the other communicates with a chamber (39) within the housing (36). An exit opening (45) at the bottom allows the second port (21) to communicate with a second pressure reservoir.