Stacked MEMS Sensor Package with Cantilevered Controller Die
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Solution Overview
Problem
Current semiconductor device packaging faces challenges in reducing the size and thickness of sensor packages while ensuring adequate space for both MEMS sensor devices and their controller ASICs, leading to issues with molding material consistency and thermal performance due to reduced sensor die sizes.
Innovation Solution
The controller die is mounted on top of the largest MEMS sensor die and optionally overhangs a second, thinner MEMS sensor die, creating a gap that allows for better molding material flow and consistency, while also being mechanically coupled to both dies to address stress and processability concerns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If sensor die size is reduced to meet area constraints, then package area is reduced, but ASIC area becomes larger than any single sensor in the package
Solution Approach 1:
The patent transitions from a two-dimensional planar arrangement to a three-dimensional stacked configuration. The ASIC is mounted on top of the sensor die, utilizing the vertical dimension to accommodate the controller while maintaining a compact footprint. This allows the ASIC to be positioned above the sensor rather than requiring lateral space, effectively resolving the area constraint issue.
Solution Approach 2:
The patent implements a nested structure where the ASIC is placed on top of the sensor die, and the entire assembly is then encapsulated within the molding compound. This nesting approach allows multiple components to occupy overlapping spatial volumes, maximizing space utilization and maintaining small package dimensions despite the presence of a relatively large ASIC.
2Adaptability or versatility
If multiple sensors and ASIC are arranged in a single package, then functionality is integrated, but area constraints are difficult to satisfy
Solution Approach 1:
By stacking the ASIC on top of the sensor die rather than placing it beside the sensor, the patent utilizes the vertical dimension to accommodate multiple functional components. This three-dimensional arrangement allows the package to maintain a small footprint while integrating both sensor and controller functionality, effectively resolving the area constraint issue.
Solution Approach 2:
The patent combines the sensor die and ASIC into a single integrated package assembly. The ASIC is mounted directly on the sensor die, and both components are encapsulated together within the same molding compound, creating a unified functional unit that maintains small overall dimensions while providing integrated sensing and processing capabilities.
3Device complexity
If controller die is mounted on sensor die, then integration is achieved, but molding material consistency and thermal performance are affected
Solution Approach 1:
The patent applies local quality by providing enhanced encapsulation specifically in the region beneath the cantilevered ASIC. The molding compound is formulated and applied to ensure adequate filling and consistency in this critical area, while allowing different material properties in other regions of the package. This localized attention to material quality ensures reliable thermal and structural performance where it is most needed.
Solution Approach 2:
The molding compound serves as an intermediary material that fills the space between the sensor die and the cantilevered ASIC. This encapsulant material provides mechanical support, thermal management, and stress distribution, mediating the interaction between the mounted ASIC and the underlying sensor die to maintain overall package reliability.
Data Source
AI summary
A small area semiconductor device package containing two or more MEMS sensor device die and a controller die for the sensor devices is provided. The controller die is mounted on top of the largest MEMS sensor device die (e.g., a gyroscope) and over a second MEMS sensor device die (e.g., an accelerometer). In one embodiment, the controller die is also mounted on the top of the second MEMS sensor device die. In another embodiment, the controller die overhangs the second MEMS sensor device die, which is of a lesser thickness than the first MEMS sensor device die.