Semiconductor Pressure Sensor Support Structure for Stable Output
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Solution Overview
Problem
Existing semiconductor pressure sensors experience variations in output voltage due to relative position deviations between piezoresistive elements and diaphragms caused by alignment inaccuracies in exposure processes.
Innovation Solution
A semiconductor pressure sensor design featuring a first silicon substrate with a diaphragm facing a recess in a second silicon substrate, where a rectangular frame-shaped support is formed within the recess, and piezoresistive elements are positioned to overlap this support, maintaining uniform strain distribution despite alignment deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If alignment accuracy of exposure process is improved, then relative position deviation between piezoresistive element and diaphragm is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
A support structure protruding from the recess bottom is introduced as an intermediary reference feature. This support provides a stable alignment reference that mediates between the exposure process and the final positioning of piezoresistive elements, reducing the need for high-precision alignment while maintaining positioning accuracy
Solution Approach 2:
The support structure is formed in advance during recess fabrication, establishing a predetermined reference framework before piezoresistive elements are positioned. This preliminary action enables subsequent alignment to be based on the pre-formed support geometry rather than requiring high-precision direct alignment
2Reliability
If relative position deviation between piezoresistive element and diaphragm is reduced, then output voltage variation is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The support structure serves as a mediator that decouples the relationship between diaphragm positioning and piezoresistive element positioning. By providing a physical reference framework, it ensures consistent strain transmission to piezoresistive elements regardless of minor alignment variations, thereby stabilizing output voltage without demanding extreme positioning precision
Solution Approach 2:
The invention changes the geometric parameters of the support structure (protrusion height, cross-sectional dimensions, shape) to optimize strain distribution. By adjusting these parameters, the system maintains reliable output voltage characteristics while accommodating broader positioning tolerances
3Reliability
If support structure is added to reduce position deviation, then output voltage variation is reduced, but device complexity increases
Solution Approach 1:
The support structure is segmented into the recess formation process and the piezoresistive element fabrication process. By dividing the manufacturing steps and using the support as a common reference between segments, the invention reduces overall system complexity while maintaining alignment accuracy and output consistency
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
Reduces variations in output voltage by ensuring consistent strain generation across the diaphragm, even with positional deviations of piezoresistive elements, thereby enhancing sensor accuracy.
Implementation Method 1
the other main surface of the first silicon substrate having piezoresistive elements formed therein
Data Source
AI summary
A semiconductor pressure sensor includes a first silicon substrate and a second silicon substrate. One main surface of the second silicon substrate has a recess formed therein. The recess has a support that protrudes toward the first silicon substrate formed therein. The support includes four side parts that are arranged to form a rectangular frame shape. The recess and the first silicon substrate have an inner cavity and an outer cavity that are formed therebetween. The inner cavity is arranged on an inner side of the support, and the outer cavity is arranged on an outer side of the support. The other main surface of the first silicon substrate has piezoresistive elements formed therein. The piezoresistive elements are arranged at or in the vicinity of a position overlapping the support, as seen from a normal direction of the first silicon substrate.