Semiconductive Structure With Isolated MEMS Cavities
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Solution Overview
Problem
The increasing complexity of semiconductive devices, particularly in MEMS applications, leads to manufacturing challenges such as high yield loss, warpage, and low signal-to-noise ratio due to the need for precise control of different operating conditions for integrated devices like accelerometers and gyroscopes, which often require distinct packaging environments.
Innovation Solution
A semiconductive structure is designed with a substrate hosting both devices, where a via allows for independent gas pressure adjustment in one cavity to match the optimal conditions for each device, and a capping structure seals the cavity, enabling operation under different gas pressures, thus optimizing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple MEMS devices are integrated on a single substrate to increase functional density, then the number of devices per chip area increases, but manufacturing complexity increases leading to high yield loss and warpage
Solution Approach 1:
The substrate is divided into multiple isolated cavities, each housing a separate MEMS device. This segmentation allows independent processing and packaging conditions for each device, reducing manufacturing complexity and yield loss while maintaining high functional density on a single substrate.
Solution Approach 2:
Each cavity is configured with specific local properties (size, shape, gas pressure, atmosphere) tailored to the requirements of the individual MEMS device it contains. This local optimization enables different devices to operate under their optimal conditions simultaneously, resolving the conflict between integration and manufacturing complexity.
2Reliability
If different MEMS devices are packaged in separate packages to maintain optimal operating conditions, then device performance is optimized, but device size and system complexity increase
Solution Approach 1:
Multiple MEMS devices that would traditionally require separate packages are merged onto a single substrate with individual cavities. This consolidation reduces system complexity and size while maintaining the performance benefits of separate packaging through cavity isolation and independent gas pressure control.
Solution Approach 2:
Multiple cavities are nested within a single substrate structure, with each cavity containing a MEMS device. This nested arrangement allows separate packaging environments to be integrated into a unified package, reducing overall system complexity while preserving individual device optimization.
3Productivity
If cavity size is reduced to accommodate more devices, then functional density increases, but manufacturing precision requirements increase leading to warpage and yield loss
Solution Approach 1:
Cavities are formed and configured during the substrate fabrication process before device assembly and packaging. This preliminary formation of cavities with precise dimensions and positions reduces subsequent manufacturing complexity and minimizes warpage, enabling high functional density without excessive precision requirements in later steps.
4Reliability
If gas pressure is controlled independently in each cavity to optimize device operation, then device performance improves, but manufacturing and control complexity increases
Solution Approach 1:
Gas pressure control is extracted to the cavity level rather than requiring complex integrated control systems. Each cavity can be independently filled and sealed with the required gas pressure during manufacturing, simplifying control complexity while enabling optimized operation for each device type.
Data Source
AI summary
A semiconductive structure includes a first substrate including a first surface and a second surface opposite to the first surface, a second substrate disposed over the first surface and including a first device and a second device, a first capping structure disposed over the second substrate, and including a via extending through the first capping structure to the second device, a first cavity surrounding the first device and defined by the first capping structure and the first substrate, a second cavity surrounding the second device and defined by the first capping structure and the first substrate, and a second capping structure disposed over the first capping structure and covering the via, wherein the second cavity and the via are sealed by the second capping structure.