Physical Quantity Sensor with Protected Conductor Pattern
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Solution Overview
Problem
Existing acceleration sensors face issues with conductor pattern damage and characteristic deterioration due to dry etching, leading to reduced accuracy and reliability in measuring acceleration.
Innovation Solution
A physical quantity sensor design featuring a substrate with a conductor pattern protected by a protection film, which covers exposed portions to prevent damage during dry etching, and includes a movable portion with through-holes to reduce air resistance and enhance detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If dry etching is used to form electrodes and wirings on the substrate, then the sensor structure can be manufactured, but the conductor pattern is damaged and characteristic deterioration occurs
Solution Approach 1:
A protection film is formed on the substrate surface before the conductor pattern is created, and this protection film is removed only from specific regions where electrodes and wirings need to be formed. This preliminary protective action prevents damage to the conductor pattern during subsequent dry etching processes, resolving the contradiction between ease of manufacture and conductor pattern integrity.
2Area of stationary object
If electrodes and wirings are disposed to overlap the element portion space, then space utilization is improved, but conductor pattern damage occurs during dry etching
Solution Approach 1:
The protection film is formed in advance across the entire substrate surface, including regions where electrodes and wirings will overlap with the element portion. This preliminary protection enables high space utilization while preventing conductor pattern damage during dry etching, as the protection film shields the conductor pattern in overlapping regions from etching damage.
3Strength
If the movable portion is solid without through-holes, then structural strength is maintained, but air resistance increases and detection sensitivity decreases
Solution Approach 1:
Through-holes are formed in the movable portion to create a porous structure. This reduces air resistance acting on the movable portion during acceleration measurement, thereby improving detection sensitivity. The through-holes are configured to minimize impact on structural strength while maximizing air resistance reduction for enhanced measurement precision.
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 prevents conductor pattern damage and characteristic deterioration, improving the accuracy and reliability of acceleration measurements while reducing air resistance and enhancing detection sensitivity.
Implementation Method 1
a protection film covering at least a part of an exposed portion of the conductor pattern exposed from the element portion in a plan view from a direction in which the substrate and the element portion overlap
Implementation Method 2
a through-hole is formed in the movable portion... air resistance when the movable portion is displaced is reduced, and detection sensitivity of the physical quantity is improved
Implementation Method 3
measures acceleration based on a change in electrostatic capacitance between the fixed comb-teeth electrode and the movable comb-teeth electrode
Data Source
AI summary
A physical quantity sensor includes a substrate, an element portion disposed so as to overlap the substrate, a conductor pattern disposed on the substrate so as to face the element portion, and a protection film covering at least a part of an exposed portion of the conductor pattern exposed from element portion in a plan view from a direction in which the substrate and the element portion overlap.