TFT Array Substrate Integrating Schottky Diodes for FPCA Miniaturization
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Solution Overview
Problem
The existing thin film transistor (TFT) array substrates and manufacturing methods result in a bulky flexible printed circuit assembly (FPCA) due to the space and thickness requirements of Schottky diodes, which hinder the miniaturization of liquid crystal modules and mobile phones.
Innovation Solution
A novel TFT array substrate design where Schottky diodes and TFTs are integrated on the same substrate, with shared layers and simplified manufacturing steps, reducing the thickness and cost of the FPCA by forming Schottky diodes and TFTs simultaneously without additional processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Schottky diodes are placed on FPCA to prevent latch up, then reliability is improved, but FPCA area and thickness increase
Solution Approach 1:
The patent merges the Schottky diode with the TFT array substrate by forming the diode's anode and cathode layers on the same substrate as the TFTs. The anode layer is formed in the non-display area, and the cathode layer is formed overlapping the anode layer with a gate insulation layer and gate layer between them. This integration eliminates the need for separate FPCA diodes, reducing FPCA area while maintaining latch-up prevention functionality.
Solution Approach 2:
The TFT array substrate is designed to serve multiple functions: it acts as both the display substrate and the carrier for Schottky diodes. The same substrate that supports TFTs in the display area also supports the anode and cathode layers in the non-display area, making the substrate universal and eliminating the need for additional FPCA components.
2Reliability
If Schottky diodes are placed on FPCA to prevent latch up, then reliability is improved, but FPCA thickness increases
Solution Approach 1:
The Schottky diode structure is merged into the TFT array substrate's layer stack. The diode's anode and cathode layers are formed within the same thickness envelope as the TFT structure, utilizing the gate insulation layer and gate layer as part of the diode's structure. This eliminates the need for additional FPCA thickness to accommodate separate diodes.
3Area of stationary object
If Schottky diodes are integrated on the same substrate as TFTs, then FPCA area and thickness are reduced, but manufacturing complexity increases
Solution Approach 1:
The anode and cathode layers of the Schottky diode are formed during the same manufacturing steps as the TFT structures. The gate insulation layer and gate layer are formed before the cathode layer, preliminary establishing the diode's internal structure. This preliminary action integrates diode formation into the existing TFT manufacturing sequence without requiring post-assembly steps.
Solution Approach 2:
The manufacturing process uses homogeneous materials and techniques for both TFTs and Schottky diodes. The same gate insulation layer material, gate electrode material, and deposition techniques are used for both device types, simplifying the manufacturing process despite the integrated structure. The uniformity of materials and processes reduces manufacturing complexity.
Data Source
AI summary
A TFT array substrate and its manufacturing method are disclosed. The TFT array substrate includes a substrate having a display area and a non-display area, and at least a Schottky diode on the non-display area. The Schottky diode includes an anode layer and a cathode layer on the substrate, a gate insulation layer on the substrate covering the anode and cathode layers, a first gate on the gate insulation layer covering portions of the anode and cathode layers, an inter-layer insulation layer on the gate insulation layer covering the first gate and having a number of vias exposing the anode and cathode layers, respectively, and a first electrode and a second electrode in the vias on the inter-layer insulation layer connecting the anode and cathode layers, respectively. The present disclosure achieves simplified manufacturing process and reduced cost by forming the Schottky diode simultaneously when the TFT is formed.