Semiconductor Die with Sacrificial Material Pressure Control
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Solution Overview
Problem
Existing micro-electronic device packaging technologies struggle to accommodate differing pressure requirements for co-located sensors within a single semiconductor die, as prior methods cannot effectively manage the distinct cavity pressure needs of devices like accelerometers and angular rate sensors.
Innovation Solution
The use of sacrificial materials within hermetically sealed cavities, which decompose into gaseous species upon heating during wafer bonding, allowing for adjustable pressure levels within the cavities to meet specific operational requirements of micro-electronic devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single hermetically sealed cavity is used to house multiple micro-electronic devices, then packaging complexity is reduced, but the ability to meet different pressure requirements of co-located sensors is compromised
Solution Approach 1:
The single cavity is divided into multiple isolated sub-cavities, each capable of maintaining different pressure levels. The segmentation is achieved through partition structures that separate the cavity space while maintaining hermetic sealing, allowing each sensor to operate in its optimal pressure environment without interfering with others.
Solution Approach 2:
Different regions of the cavity structure are assigned different pressure characteristics to match the specific requirements of each sensor type. Accelerometers are placed in regions maintained at higher pressure while angular rate sensors are placed in vacuum or low-pressure regions, creating local quality variations within the overall packaging structure.
2Adaptability or versatility
If separate hermetically sealed cavities are created for each sensor type, then pressure requirements are met, but packaging complexity and manufacturing difficulty increase
Solution Approach 1:
Multiple cavity structures are merged into a single integrated packaging unit that houses all sensors. The merging process combines what would traditionally be separate vacuum and atmospheric pressure packages into one unified structure, reducing the total number of discrete components while maintaining the ability to provide different pressure environments through internal partitioning.
Solution Approach 2:
The cavity structure is designed to serve multiple functions simultaneously: it provides hermetic sealing, mechanical support, pressure regulation zones, and thermal management pathways. This multi-functionality reduces the need for additional specialized components that would otherwise be required to achieve the same performance.
3Ease of manufacture
If traditional packaging methods are used, then manufacturing processes are simple, but co-located sensors cannot operate at their optimal pressure levels
Solution Approach 1:
Pressure control features such as sacrificial materials, vent holes with specific geometries, and partition structures are incorporated into the packaging design during the fabrication process. These preliminary actions establish the pressure characteristics before final assembly, ensuring that sensors are placed in the correct pressure environment from the outset without requiring complex post-assembly adjustments.
Solution Approach 2:
The packaging structure incorporates features that allow pressure parameters to be controlled and maintained at different levels within the same package. This includes using sacrificial materials that decompose at specific temperatures to create vacuum, designing vent hole geometries that regulate pressure, and creating partition structures that isolate different pressure zones, thereby enabling each sensor to operate at its optimal pressure parameter.
Data Source
AI summary
A semiconductor die includes a device structure having a micro-electronic device located at a surface of a substrate and a cap coupled to the device structure with the micro-electronic device positioned in a cavity located between the cap and the substrate. A sacrificial material is provided within the cavity, coupling the cap to the device structure. The sacrificial material is heated in the cavity to cause the sacrificial material to decompose to a gaseous species. The presence of the gaseous species in the cavity increases a pressure level in the cavity from an initial pressure to a final pressure.