TFT Array Substrate Fabrication via Gate Electrode Ion Blocking
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Solution Overview
Problem
The existing methods for fabricating thin film transistor (TFT) array substrates suffer from reliability issues due to mobile ions moving from photoresist patterns to semiconductor layers through the gate insulating layer during photolithography processes, affecting the operation of PMOS and NMOS TFTs and complicating the fabrication process.
Innovation Solution
The method involves forming channel-doped semiconductor layers and lower electrodes of TFTs and storage capacitors using low-dose ion doping before forming the gate insulating layer, and performing photolithography processes for ion injection after the gate electrodes are formed, preventing mobile ions from reaching the channels and simplifying the fabrication process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If photolithography processes are performed before forming gate electrodes, then source and drain regions can be formed, but mobile ions from photoresist patterns move to semiconductor layers through gate insulating layer, deteriorating TFT reliability
Solution Approach 1:
Gate electrodes are formed in advance before performing photolithography processes for source and drain region formation. This preliminary action creates a physical barrier that prevents mobile ions from photoresist patterns from reaching semiconductor layers during subsequent ion injection processes, thereby maintaining TFT reliability while enabling complete fabrication processes.
Solution Approach 2:
Gate electrodes serve as an intermediary barrier between photoresist patterns and semiconductor layers. During photolithography processes, the gate electrodes block the migration path of mobile ions from photoresist through gate insulating layer to semiconductor layers, preventing deterioration of TFT characteristics.
2Manufacturing precision
If multiple photolithography processes are performed for ion injection, then source and drain regions can be formed, but the fabrication process becomes complicated
Solution Approach 1:
Gate electrodes are formed preliminarily before ion injection photolithography processes. This preliminary structure enables subsequent photolithography processes to be performed with better control and precision, as the gate electrodes provide defined boundaries and masks for source and drain region formation.
Solution Approach 2:
The gate electrodes provide structural feedback and guidance during photolithography processes. The presence of gate electrodes allows for precise alignment and control of photoresist patterns during ion injection, ensuring accurate source and drain region formation while simplifying the overall process control.
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 enhances the reliability of PMOS and NMOS TFTs by reducing the impact of mobile ions and simplifies the fabrication process, leading to stable operation and reduced production costs by eliminating the need for additional photolithography steps.
Implementation Method 1
forming channel-doped semiconductor layers and lower electrodes of TFTs and storage capacitors using low-dose ion doping
Implementation Method 2
performing photolithography processes for ion injection after the gate electrodes are formed
Data Source
AI summary
A method of fabricating a TFT array substrate that prevents mobile ions from moving from a photoresist to channels of the TFT by the gate electrode of the TFT by performing photolithography processes for ion injection after forming gate electrode of TFT and, in addition, a method of fabricating a TFT array substrate that omits a photolithography process for forming a lower electrode of a storage capacitor by forming the lower electrode of the storage capacitor by a channel doping process for a PMOS TFT.