Flat Panel Detector Substrate Layout for IGZO Hydrogen Stability
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Solution Overview
Problem
The stability of Indium Gallium Zinc Oxide (IGZO) thin film transistors in flat panel X-ray detectors is compromised due to hydrogen sensitivity, leading to increased conductivity and leakage current under X-ray irradiation, affecting the performance of the detectors.
Innovation Solution
A detection substrate design with a thin film transistor having a channel region within a via hole in a dielectric layer, a sacrificial layer between the transistor and photoelectric conversion part, and a bias voltage line structure that includes a third passivation layer to isolate hydrogen atoms, enhancing the stability and reducing conductivity issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If IGZO thin film transistor is used to improve carrier mobility, then the carrier mobility increases from 0.1-1 to 5-20, but the transistor becomes sensitive to hydrogen atoms causing increased conductivity and leakage current
Solution Approach 1:
A sacrificial layer (oxide layer) is introduced between the IGZO TFT and the photoelectric conversion part to act as a mediator. This layer blocks hydrogen atoms from the photoelectric conversion part from diffusing into the IGZO active layer, thereby protecting the high-mobility IGZO TFT from hydrogen-induced degradation while maintaining the carrier mobility advantage
Solution Approach 2:
The patent converts the harmful effect of hydrogen sensitivity into a benefit by using the hydrogen-blocking property of the sacrificial oxide layer. The layer that would normally be considered an additional component is actually utilizing the hydrogen-exclusion characteristic to protect the IGZO TFT, turning the potential harm into a protective mechanism
2Strength
If a silicon nitride layer is fabricated to protect the structure, then the structural integrity is improved, but hydrogen atoms diffuse through the layer toward the IGZO thin film transistor
Solution Approach 1:
The patent uses a composite structure combining silicon nitride layer (for structural integrity) with an oxide sacrificial layer (for hydrogen blocking). This composite approach allows both functions to coexist: the silicon nitride provides mechanical strength while the oxide layer prevents hydrogen diffusion to the IGZO TFT
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 design effectively reduces hydrogen content in the channel region, improving the stability and performance of the thin film transistor, thereby enhancing the overall performance of the flat panel X-ray detector.
Implementation Method 1
hydrogen atoms may diffuse toward the IGZO thin film transistor; the permeation of excess H atoms into a-IGZO active layer
Implementation Method 2
at least one dielectric layer is provided between the photoelectric conversion part and the bias voltage line... at least part of an orthographic projection of the channel region on the base substrate is located within an orthographic projection of the first via hole on the base substrate
Implementation Method 3
a photoelectric conversion part located on a side, away from the base substrate, of the thin film transistor
Data Source
AI summary
The present disclosure provides a detection substrate, including: a base substrate, detection pixel units arranged in an array on the base substrate, where each detection pixel unit includes: a thin film transistor and a photoelectric conversion part located on a side of the thin film transistor, and a bias voltage line is arranged on a side of the photoelectric conversion part. The thin film transistor includes: an active layer, a first electrode and a second electrode, and the active layer including a channel region. At least one dielectric layer is provided between the photoelectric conversion part and the bias voltage line, and is formed with a first via hole therein, and at least part of an orthographic projection of the channel region on the base substrate is located within an orthographic projection of the first via hole on the base substrate. A flat panel detector is further provided.