Pressure Sensor Diaphragm Trench Beam Segmentation
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Solution Overview
Problem
Existing pressure sensors face challenges in achieving both high detection sensitivity and output linearity, with previous designs either improving sensitivity at the expense of linearity or vice versa.
Innovation Solution
A pressure sensing element formed on a semiconductor substrate with a diaphragm featuring trenches and beams, where the beams have a narrow portion connecting to a wide portion, and the diaphragm includes a frame with protrusions, allowing for improved deformation and piezoresistor placement to enhance sensitivity and linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a trench is formed on the diaphragm to improve detection sensitivity, then detection sensitivity is improved, but output linearity deteriorates
Solution Approach 1:
The diaphragm is segmented into multiple regions with different thicknesses: a trench portion (thin), a beam portion (thick), and a boss portion (thick). This segmentation allows different regions to serve different functions - the thin trench region enhances sensitivity while the thick beam and boss regions maintain structural integrity and improve output linearity by controlling deformation patterns.
Solution Approach 2:
Different portions of the diaphragm are given different local properties through selective etching. The trench portion has reduced thickness for high sensitivity, while the beam and boss portions retain full thickness for structural support and linearity. The beams connect these regions, creating a gradient structure that optimizes both sensitivity and linearity locally in different areas.
2Manufacturing precision
If a boss is added to the center of the diaphragm to improve output linearity, then output linearity is improved, but detection sensitivity deteriorates
Solution Approach 1:
The diaphragm structure is divided into functionally distinct segments: a central boss portion for linearity, surrounding beam portions for connection and stress distribution, and trench portions for sensitivity. This segmentation allows the boss to improve linearity without completely dominating the deformation behavior, as the trench regions remain thin and responsive to pressure changes.
Solution Approach 2:
The diaphragm creates a composite structure with regions of different effective thicknesses and mechanical properties. The thick boss and beam regions combined with thin trench regions form a composite system where the overall behavior balances linearity and sensitivity, achieving both objectives simultaneously through spatial variation in material distribution.
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
The solution effectively improves both detection sensitivity and output linearity by optimizing the deformation mechanism of the diaphragm and strategically placing piezoresistors, avoiding the reduction in sensitivity while maintaining high linearity.
Implementation Method 1
providing a piezoresistor which detects the distortion of diaphragm as the change in resistance on the diaphragm. Thus, the pressure can be measured by detecting the change in electrical resistance of the piezoresistor caused by the distortion of diaphragm when the pressure is applied.
Data Source
AI summary
Disclosed is a pressure sensing element that is formed using a semiconductor substrate, the pressure sensing element including: a frame; a diaphragm that is supported by the frame; and a piezoresistor that is arranged on the diaphragm. The diaphragm includes a trench and a plurality of beams, the beams are arranged such that the beams connect a portion around an edge of the diaphragm to a portion around a center of the diaphragm and the beams cross each other in the portion around the center of the diaphragm, and a beam that is each of the beams includes a narrow portion that has a first width and a wide portion that has a second width wider than the first width.