ICP Etching Rework for Thin Film Transistor Gate Insulating Layers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional manufacturing processes for liquid crystal display panels require discarding the entire substrate when chemical vapor deposition processes fail, leading to increased costs and reduced yield due to the inability to rework chemical-related film formations.
Innovation Solution
A rework method using an inductively coupled plasma (ICP) etching process with sulfur hexafluoride and oxygen gases to selectively remove a silicon nitride gate insulating layer without damaging the glass substrate, allowing for subsequent reformation and maintaining substrate quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a chemical vapor deposition (CVD) process is used to form a gate insulating layer, then the film quality can be improved, but the entire substrate must be discarded if the film formation fails or quality is abnormal
Solution Approach 1:
The invention segments the removal process into two distinct stages: first removing the gate insulating layer (silicon nitride) through ICP etching, and then removing the gate electrode through wet etching. This segmentation allows selective removal of only the defective layer while preserving the substrate and other structures, enabling rework without discarding the entire substrate.
Solution Approach 2:
The invention changes the etching parameters by using ICP etching with specific gas compositions (CF4, SF6, O2) and power settings (2000-3000W) to achieve high etching selectivity between silicon nitride and glass substrate. This parameter optimization enables precise removal of the gate insulating layer while protecting the substrate, transforming the irreversible CVD process into a reversible, reworkable process.
2Reliability
If the entire substrate is discarded when film formation fails, then the manufacturing cost increases and array substrate yield decreases
Solution Approach 1:
The invention implements a discarding and recovering strategy by removing only the defective gate insulating layer and gate electrode, then recovering and reusing the substrate for forming a new gate insulating layer. This approach recovers the valuable substrate material and enables multiple production cycles from a single substrate, improving yield and reducing manufacturing costs.
Solution Approach 2:
By optimizing ICP etching parameters (gas flow rates, power, pressure) to achieve high selectivity, the invention enables cost-effective rework processes. The precise parameter control ensures that only the necessary layers are removed without damaging the substrate, making the rework process economically viable and improving overall manufacturing efficiency.
3Manufacturing precision
If an ICP etching process is used to remove the silicon nitride layer, then the etching selectivity can be improved, but the process complexity increases
Solution Approach 1:
The invention segments the removal process into two distinct stages: first removing the gate insulating layer (silicon nitride) through ICP etching, and then removing the gate electrode through wet etching. This segmentation allows selective removal of only the defective layer while preserving the substrate and other structures, enabling rework without discarding the entire substrate.
Solution Approach 2:
The invention uses an intermediary approach by first removing the gate insulating layer through ICP etching before proceeding to remove the gate electrode through wet etching. This intermediary step ensures that the etching process is performed in a controlled sequence, preventing direct exposure of the gate electrode to aggressive etching conditions and enabling precise control over the removal process.
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
Enables the removal of abnormal silicon nitride layers with high etching selectivity, preventing substrate damage and allowing for cost-effective rework processes, thus reducing manufacturing costs and improving yield.
Implementation Method 1
performing an ICP etching process to etch away the silicon nitride layer. The ICP etching process is carried out by introducing gases including sulfur hexafluoride
Implementation Method 2
The ICP etching process is carried out by introducing gases including sulfur hexafluoride with a flow rate that is substantially between 300 sccm and 500 sccm, and oxygen with a flow rate that is substantially between 150 sccm and 350 sccm
Implementation Method 3
the ICP etching process has a high etching selectivity ratio of silicon nitride to glass. As a result, the silicon nitride layer is able to be removed without damaging the glass substrate
Data Source
AI summary
A rework method of a gate insulating layer of a thin film transistor includes the following steps. First, a substrate including a silicon nitride layer, which serves as a gate insulating layer, disposed thereon. Subsequently, a first film removal process is performed to remove the silicon nitride layer. The first film removal process includes an inductively coupled plasma (ICP) etching process. The ICP etching process is carried out by introducing gases including sulfur hexafluoride and oxygen. The ICP etching process has an etching selectivity ratio of the silicon nitride layer to the substrate, which is substantially between 18 and 30.