Vertical Thin Film Transistor Fingerprint Sensor Design
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Solution Overview
Problem
Existing fingerprint identification sensors face challenges in achieving thin film formation and miniaturization while maintaining high identification efficiency, requiring innovative structural arrangements and manufacturing methods to reduce complexity and increase the area occupied by photosensitive devices.
Innovation Solution
A fingerprint identification sensor with a vertical-type thin film transistor arrangement, where the source, drain, and gate are positioned in a direction perpendicular to the substrate surface, integrated with a photosensitive device, and a black resin layer is used to enhance light shielding and simplify the fabrication process, allowing for increased photosensitive device area and improved efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If conventional planar thin film transistor arrangement is used, then manufacturing process is simpler, but photosensitive device area is reduced and identification efficiency decreases
Solution Approach 1:
The patent transitions from a conventional planar (2D) transistor arrangement to a vertical (3D) transistor structure where the active layer extends in the thickness direction of the substrate. This dimensional change allows the photosensitive device area in the plane of the substrate to be maximized while the transistor channel is formed vertically, resolving the contradiction between increasing photosensitive area and maintaining structural simplicity.
2Manufacturing precision
If more masks are used in manufacturing, then manufacturing precision is improved, but manufacturing process complexity and cost increase
Solution Approach 1:
The patent combines the formation of the transistor active layer and the photosensitive device structure into a single manufacturing process step. The active layer is formed to extend from the gate electrode through the photosensitive device region, allowing both structures to be created simultaneously with fewer masking steps, thereby reducing process complexity while maintaining precision.
3Volume of moving object
If thin film formation is pursued, then miniaturization is achieved, but device performance and identification efficiency may deteriorate
Solution Approach 1:
The patent maintains thin film overall thickness while relocating the transistor channel formation to the vertical dimension. The active layer extends in the thickness direction, allowing sufficient channel length for proper transistor function to be achieved within the thin film constraint, thus maintaining identification efficiency while achieving miniaturization.
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 vertical-type thin film transistor arrangement reduces the number of masks required in manufacturing, simplifies the process, and increases the area for photosensitive devices, enhancing the identification efficiency and meeting the requirements of thin film formation and miniaturization.
Implementation Method 1
each of the sensor units comprising a thin film transistor and a photosensitive device
Data Source
AI summary
A fingerprint identification sensor, a method of fabricating the same, and a fingerprint identification apparatus are provided. The fingerprint identification sensor includes: a substrate; a plurality of sensor units on the substrate, each of the sensor units comprising a thin film transistor and a photosensitive device; wherein the thin film transistor comprises a source and a drain, an active layer and a gate, the source and the drain being arranged substantially in a direction perpendicular to the substrate surface.