Pyroelectric Sensor Thinning via Sputtered Piezoelectric Film
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Solution Overview
Problem
Existing pyroelectric sensors used in portable devices, such as smartphones, face challenges in thinning due to the bulk nature of pyroelectric ceramic materials and complex handling issues during polishing and bonding, making it difficult to achieve a thickness of less than 1.0 mm.
Innovation Solution
A pyroelectric sensor configuration featuring a laminated structure on a silicon substrate with a heat absorption layer, a lower electrode, a piezoelectric film, and an upper electrode, where the piezoelectric film is sputtered and has a thickness of less than 10 μm, and an optical filter on the opposite surface to selectively transmit infrared rays, allowing for high sensitivity and reduced thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If bulk pyroelectric ceramic is used, then the sensor has sufficient rigidity and handling properties, but the thickness becomes equal to or greater than 1 mm
Solution Approach 1:
The patent changes the physical state of the pyroelectric material from bulk ceramic to thin film form. The piezoelectric film has a thickness of 1 μm to 10 μm, which is 100-1000 times thinner than bulk ceramic, enabling the sensor thickness to be reduced to 1 mm or less while maintaining functional performance
Solution Approach 2:
The patent replaces mechanical polishing and bonding operations with sputtering deposition. The piezoelectric film is formed by sputtering a piezoelectric target onto a silicon substrate, eliminating the need for mechanical thinning and associated handling difficulties
2Length of moving object
If bulk pyroelectric ceramic is used, then the sensor structure is simple, but the thickness becomes equal to or greater than 1 mm
Solution Approach 1:
The patent segments the sensor into distinct functional layers: silicon substrate, heat absorption layer, piezoelectric film, and electrode. This layered structure allows each component to be optimized independently and facilitates thinning to 1 mm or less while maintaining structural integrity
Solution Approach 2:
The patent uses composite material structure combining silicon substrate with sputtered piezoelectric film and heat absorption layer. This composite approach enables the sensor to achieve reduced thickness while maintaining rigidity and functional performance through material synergies
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 configuration enables the realization of a significantly thinned pyroelectric sensor with enhanced sensitivity and improved handling properties, suitable for integration into portable devices without increasing thickness beyond 1.0 mm.
Implementation Method 1
The pyroelectric element detects an infrared ray by using a pyroelectric effect in which polarization (surface charge) occurs due to a temperature change
Implementation Method 2
an optical filter that is provided at a position of the other surface of the Si substrate corresponding to the laminated portion and selectively transmits an infrared ray
Implementation Method 3
the piezoelectric film is sputtered
Data Source
AI summary
Provided is a pyroelectric sensor including: an Si substrate; a laminated portion in which a heat absorption layer formed of an inorganic material, a lower electrode, a piezoelectric film, and an upper electrode are laminated in this order from one surface side of the Si substrate on the one surface; and an optical filter that is provided at a position of the other surface of the Si substrate corresponding to the laminated portion and selectively transmits an infrared ray, in which an infrared ray incident to the laminated portion from the optical filter side through the Si substrate is sensed.