Fingerprint Sensor Stacked Photosensitive Element TFT
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Solution Overview
Problem
The small arrangement space of photosensitive elements in fingerprint recognition sensors due to adjacent placement with thin film transistors results in a reduced effective photosensitive area, leading to low accuracy and weak photocurrent signals, especially in high-density display devices.
Innovation Solution
The photosensitive element and thin film transistor are stacked perpendicularly on opposite sides of a base substrate with a conductive structure penetrating through, allowing for increased effective photosensitive area and improved connectivity, using transparent electrodes and optimized material matching to enhance light transmittance and reduce dark current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the photosensitive element and thin film transistor are disposed adjacently on the same side of the base substrate, then the device layout is simplified, but the effective photosensitive area is reduced and fingerprint recognition accuracy deteriorates
Solution Approach 1:
The patent transitions from a planar arrangement to a three-dimensional stacked configuration. The photosensitive element and thin film transistor are positioned on opposite sides of the base substrate and connected through conductive structures penetrating the substrate, effectively utilizing the vertical dimension to resolve the spatial conflict between these two components.
Solution Approach 2:
The conductive structure is embedded within the base substrate, with portions extending from both sides. This nested configuration allows the conductive structure to be integrated into the substrate while providing electrical connection between the photosensitive element and thin film transistor, optimizing space utilization.
2Measurement precision
If the photosensitive element area is increased to improve fingerprint recognition accuracy, then the recognition accuracy is improved, but the arrangement space is insufficient and device integration becomes difficult
Solution Approach 1:
By moving the thin film transistor to the opposite side of the base substrate relative to the photosensitive element, the patent enables the photosensitive element to occupy a larger area on the front surface without increasing lateral device footprint. This vertical separation allows full utilization of the substrate area for photosensitive elements.
Solution Approach 2:
The device is segmented into distinct functional layers on opposite sides of the substrate: the photosensitive element on one side and the thin film transistor on the other, connected through conductive pathways. This segmentation allows each component to be optimized independently for its respective function.
3Reliability
If more conductive structures are added to connect photosensitive elements and transistors, then electrical connectivity is improved, but manufacturing complexity and noise increase
Solution Approach 1:
The conductive structures serve multiple functions simultaneously: they provide electrical connection between the photosensitive element and thin film transistor, act as structural integration elements within the substrate, and establish signal pathways. This multi-functionality reduces the need for separate dedicated connection structures.
Solution Approach 2:
The patent merges the conductive connection function with the substrate structure itself. The conductive structures are integrated into the base substrate rather than being separate added components, combining structural support and electrical connectivity functions into a unified design.
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 increases the effective photosensitive area, enhances photocurrent signals, and improves fingerprint recognition accuracy, simplifying the manufacturing process while reducing noise and light loss.
Implementation Method 1
the base substrate includes a conductive structure penetrating through the base substrate in the thickness direction perpendicular to the base substrate, and the photosensitive element is connected with the thin film transistor through the conductive structure
Implementation Method 2
a photosensitive layer on a side of the first electrode away from the base substrate
Data Source
AI summary
Disclosed are a fingerprint recognition sensor, a manufacturing method, and a display device. The fingerprint recognition sensor includes a base substrate, a thin film transistor, on a side of the base substrate; and a photosensitive element, on a side of the base substrate away from the thin film transistor, the thin film transistor, the base substrate, and the photosensitive element are sequentially stacked in a thickness direction perpendicular to the base substrate, the base substrate includes a conductive structure penetrating through the base substrate in the thickness direction perpendicular to the base substrate, and the photosensitive element is connected with the thin film transistor through the conductive structure.