TFT-LCD Pixel Structure Indium Residue Removal
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Solution Overview
Problem
In the fabrication of Thin Film Transistor-Liquid Crystal Display (TFT-LCD) pixel structures, indium-containing material remains on the sides of source and drain electrodes, leading to poor quality and high leakage current due to incomplete etching and misalignment of photoresist patterns.
Innovation Solution
A method involving the ashing of photoresist patterns to align their edges with the electrodes, followed by etching of silicon oxide and semiconductor layers to ensure the channel width matches the electrode distance, thereby preventing indium residue and semiconductor steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photoresist pattern is used to etch source-drain electrode layer and semiconductor layer, then source electrode and drain electrode are formed, but indium-containing material remains on both sides of the electrodes and channel width is less than electrode distance
Solution Approach 1:
The photoresist pattern is divided into multiple segments: a first photoresist pattern for etching the source-drain electrode layer, and a second photoresist pattern for etching the semiconductor layer. The second pattern extends beyond the first pattern's edges, allowing plasma to access and remove indium residue that would otherwise be blocked by a single continuous photoresist layer.
Solution Approach 2:
The solution transitions from a two-dimensional planar photoresist pattern to a three-dimensional structured approach where the second photoresist pattern is positioned at a different spatial location (extending beyond the edges of the first pattern). This dimensional extension allows plasma to reach previously blocked areas for effective indium removal.
2Reliability
If photoresist pattern blocks outer edge during etching, then source and drain electrodes are formed, but indium-containing material remains on both sides
Solution Approach 1:
The photoresist protection is segmented into two distinct patterns: the first pattern protects the electrode formation area, while the second pattern selectively exposes the outer edge regions where indium residue accumulates. This segmentation allows differential treatment of different areas during the etching process.
Solution Approach 2:
The second photoresist pattern acts as an intermediary structure that modifies the plasma distribution. It allows plasma to reach the outer edge regions through its extended structure, enabling indium removal without compromising the electrode formation quality protected by the first photoresist pattern.
3Shape
If photoresist pattern blocks inner edge during etching, then electrode structure is maintained, but channel width is reduced creating semiconductor step
Solution Approach 1:
The etching process is segmented into two stages with two different photoresist patterns. The first pattern maintains electrode structure integrity during source-drain electrode layer etching, while the second pattern ensures full channel width etching by extending beyond the first pattern's boundaries, preventing semiconductor step formation.
Solution Approach 2:
The first photoresist pattern is applied preliminarily to define the electrode structure boundaries. Then the second photoresist pattern is applied to ensure complete channel etching. This preliminary structuring allows subsequent etching to achieve both electrode integrity and full channel width without semiconductor steps.
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 method improves the quality of TFT-LCD by removing indium-containing material and eliminating semiconductor steps, reducing leakage current and enhancing the overall performance of the display device.
Implementation Method 1
ashing the photoresist pattern
Implementation Method 2
when plasma bombards the ITO
Data Source
Figure 1~2
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Figure 5~6
AI summary
Provided is a pixel structure manufacturing method. The manufacturing method comprises: forming a gate (12), a gate insulation layer (13), an active layer (17), a pixel electrode layer (14) and a source/drain electrode layer on a substrate (11), and etching the source/drain electrode layer by using photoresist patterns (18) so as to form a source (16) and a drain (15); performing ashing on the photoresist patterns (18), so that the photoresist patterns (18) on which ashing is performed are aligned to edges of the source (16) and the drain (15); etching silicon oxide generated when ashing is performed on the photoresist patterns (18); and etching, by using an etching process, a semiconductor layer (17) between the source (16) and the drain (15) so as to form a channel (19). By means of the manufacturing method, an indium-containing material residual on two sides of the source and the drain can be eliminated, and the problem that the width of a channel between the source and the drain is small can be solved.