Segmented Stress Decoupling Trenches for MEMS Sensor Accuracy
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Solution Overview
Problem
Mechanical stress transferred through the package to MEMS elements, such as pressure sensors, can cause offset, linearity, and hysteresis errors in sensor signals due to housing deformation, leading to incorrect measurements.
Innovation Solution
Incorporating stress-decoupling trenches and spring structures in the semiconductor chip substrate to absorb external stress, with trenches extending partially into the substrate and spring structures formed between them to reduce stress transfer to the MEMS elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the sensor is integrated into a chip package, then the device can be manufactured using standard semiconductor fabrication processes, but mechanical stress from the package is transferred to the sensor causing measurement errors
Solution Approach 1:
The substrate is segmented by introducing stress-decoupling trenches that divide the continuous substrate into separate regions. These trenches create mechanical isolation zones that prevent stress transfer from the package to the sensor while maintaining the integrated circuit structure. The sensor region is segmented from the package mounting area, allowing independent stress management.
Solution Approach 2:
Spring structures are introduced as intermediary elements between the package and the sensor. These spring structures act as mechanical mediators that absorb and isolate external stress, preventing it from reaching the sensor. The springs provide a compliant interface that decouples the rigid package from the stress-sensitive sensor region.
2Measurement precision
If stress-decoupling trenches are introduced to isolate the sensor from mechanical stress, then measurement accuracy is improved, but the device structure becomes more complex
Solution Approach 1:
The substrate is segmented by introducing stress-decoupling trenches that divide the continuous substrate into separate regions. These trenches create mechanical isolation zones that prevent stress transfer from the package to the sensor while maintaining the integrated circuit structure. The sensor region is segmented from the package mounting area, allowing independent stress management.
Solution Approach 2:
Spring structures with flexible, membrane-like characteristics are integrated into the substrate. These thin, elastic structures provide stress absorption and isolation while maintaining a minimal structural footprint. The flexible spring structures conform to the substrate and provide compliance without adding significant structural complexity.
3Reliability
If spring structures are added to absorb external stress, then sensor protection from mechanical stress is improved, but the device requires additional manufacturing steps
Solution Approach 1:
The spring structures are merged with the substrate formation process, integrating the stress-absorption function into the existing substrate preparation steps. The trenches and springs are formed as part of the substrate fabrication sequence, combining multiple functions (stress isolation, structural support, and sensor protection) into a unified manufacturing flow rather than adding separate post-processing steps.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively decouples mechanical stress from MEMS elements, maintaining sensor functionality and preventing signal shifts, thereby improving measurement accuracy and robustness against environmental stress.
Implementation Method 1
a first spring structure formed between the first pair of adjacent stress-decoupling trenches such that the first spring structure is arranged laterally from the stress-sensitive sensor and is configured to absorb external stress from an environment
Data Source
AI summary
A semiconductor device includes a first region; a second region that is peripheral to the first region; a substrate having a first surface and a second surface arranged opposite to the first surface; a stress-sensitive sensor disposed in the first region at the first surface of the substrate; a back end of line (BEOL) stack disposed on the first surface of the semiconductor chip that extends laterally from the MEMS element, in the first region, into the second region; a first cavity formed in the BEOL stack that exposes the sensitive area of the stress-sensitive sensor, wherein the first cavity extends entirely through the BEOL stack over the first region thereby exposing a sensitive area of the stress-sensitive sensor; and at least one stress-decoupling trench laterally spaced from the stress-sensitive sensor and laterally spaced from the first cavity with a portion of the BEOL stack interposed between.