Polysilicon Display Panel Layout for Integrated TFT-Photodiode Pixels
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Solution Overview
Problem
Conventional medical amorphous silicon panel detectors have a thick structure due to the separate fabrication of thin film transistors and photodiodes, leading to increased optical path interference, larger occupied area, lower resolution, and higher production costs.
Innovation Solution
A display panel is designed with a polysilicon thin film transistor on a glass substrate, where an amorphous silicon photodiode is formed simultaneously through ion implantation, creating a PN structure for improved light recognition with reduced complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thin film transistor and amorphous silicon photodiode are fabricated separately with multiple film formation and lithography steps, then device functionality is achieved, but production cost increases and manufacturing complexity increases
Solution Approach 1:
The patent combines the fabrication of thin film transistors and amorphous silicon photodiodes into a single integrated process. The polysilicon layer serves dual purposes: as the active layer for thin film transistors and as the base for forming amorphous silicon photodiodes through subsequent ion implantation. This merging eliminates separate fabrication steps, reduces manufacturing complexity, and lowers production costs while maintaining both device functionalities.
2Area of stationary object
If thin film transistor and amorphous silicon photodiode are disposed separately with distance between them, then device functionality is achieved, but occupied area increases and resolution decreases
Solution Approach 1:
The patent merges the thin film transistor and amorphous silicon photodiode into a single integrated structure where they share common layers and regions. The polysilicon layer forms both the transistor channel and the photodiode base, eliminating the need for separate disposal and reducing the overall pixel unit area. This integration directly improves resolution by reducing the occupied area per pixel.
Solution Approach 2:
The patent implements a nested structure where the amorphous silicon photodiode is formed within the same polysilicon layer region as the thin film transistor. The ion implantation process creates the photodiode structure nested within the transistor fabrication framework, allowing both devices to coexist in a compact integrated footprint, thereby reducing pixel area and enhancing resolution.
3Reliability
If intermediate layer of amorphous silicon photodiode has thickness of about 1 micrometer, then photodiode functionality is achieved, but panel detector thickness increases
Solution Approach 1:
The patent changes the thickness parameter of the polysilicon layer used for the photodiode from the conventional 1 micrometer to a thinner configuration. By optimizing the polysilicon layer thickness and using ion implantation to create the appropriate doping profile, the patent achieves adequate photodiode detection capability with reduced thickness, thereby reducing the overall panel detector thickness while maintaining functionality.
4Device complexity
If polysilicon layer is used for both thin film transistor and amorphous silicon photodiode, then manufacturing cost reduces and process complexity reduces, but doping precision control becomes more challenging
Solution Approach 1:
The patent applies preliminary ion implantation doping to the polysilicon layer before forming the gate structure. This preliminary doping action establishes the base electrical characteristics of the polysilicon, enabling subsequent processing steps to work with pre-conditioned material. This approach simplifies the overall process while maintaining doping precision by preparing the polysilicon layer in advance with the required electrical properties.
Solution Approach 2:
The patent replaces traditional mechanical or chemical doping methods with ion implantation technology. Ion implantation provides precise control over doping concentration and depth through adjustable ion energy and dosage parameters, enabling accurate doping precision control even when using the same polysilicon layer for both transistor and photodiode fabrication. This substitution of doping methodology resolves the precision control challenge.
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 approach allows for better signal-to-noise ratio and simultaneous fabrication of thin film transistors and photodiodes, reducing production costs and enhancing resolution without additional complex structures or processes.
Implementation Method 1
an amorphous silicon photodiode is formed simultaneously through ion implantation
Data Source
AI summary
A display panel and a manufacturing method thereof are provided. The display panel comprises a glass substrate, an insulating layer, a polysilicon layer, a gate insulating layer, a gate layer, an interlayer insulating layer, and a source-drain contacting layer, wherein the polysilicon layer is defined with a first doped region, a second doped region, and a third doped region. The source-drain contacting layer contacts the first doped region and the third doped region. A doping type of the first doped region and a doping type of the third doped region are different so that the first doped region and the third doped region form a PN structure. Doping type of the first doped region and a doping type of the second doped region are same.