TFT Array Substrate Source Wire Projection for Defect Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional liquid crystal display devices in fringe field switching mode require six photolithography steps to manufacture a thin film transistor array substrate, leading to increased manufacturing costs and a high likelihood of cross talk point defects due to pattern defects between the pixel electrode and source wire, which are difficult to detect.
Innovation Solution
A thin film transistor array substrate is designed using five photolithography steps with a semiconductor film under the drain electrode, source electrode, and source wire, where the semiconductor film projects beyond the source wire, enhancing the detectability of pattern defects during inspection by creating a significant brightness difference between normal and defective patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If five photolithography steps are used to manufacture the TFT array substrate, then manufacturing cost is reduced, but the detectability of pattern defects between pixel electrode and source wire deteriorates
Solution Approach 1:
The patent performs pattern defect inspection at an intermediate stage during the five-step photolithography process, before the final pixel electrode pattern is completed. By inspecting the source wire pattern and surrounding regions earlier in the manufacturing sequence, the method detects potential defects that could lead to cross-talk before they become irreparable, thus maintaining high detectability while using fewer photolithography steps
Solution Approach 2:
The patent introduces an intermediary inspection region between the source wire and the pixel electrode forming region. This intermediary zone serves as a detection buffer that enhances the visibility of pattern defects during optical inspection, allowing defects to be detected with high contrast even when using a simplified five-step manufacturing process
2Device complexity
If the transparent conductive film is arranged on the source wire without an insulating film, then the number of photolithography steps is reduced to five, but cross talk point defects become more prone to occur
Solution Approach 1:
The patent performs pattern defect inspection at an intermediate stage during the five-step photolithography process, before the final pixel electrode pattern is completed. By inspecting the source wire pattern and surrounding regions earlier in the manufacturing sequence, the method detects potential defects that could lead to cross-talk before they become irreparable, thus maintaining high detectability while using fewer photolithography steps
Solution Approach 2:
The patent replaces physical structural prevention (insulating films) with a detection-and-repair system. Instead of using additional insulating layers to prevent cross-talk, the method relies on optical inspection to detect pattern defects and uses laser repair technology to remove defects that cause cross-talk, substituting mechanical prevention with optical detection and targeted removal
3Measurement precision
If pattern defect inspection is performed after pixel electrode patterning, then the position of cross talk point defects can be specified, but the brightness difference between normal and defective spots is insufficient for accurate detection
Solution Approach 1:
The patent performs pattern defect inspection at an intermediate stage during the five-step photolithography process, before the final pixel electrode pattern is completed. By inspecting the source wire pattern and surrounding regions earlier in the manufacturing sequence, the method detects potential defects that could lead to cross-talk before they become irreparable, thus maintaining high detectability while using fewer photolithography steps
Solution Approach 2:
The patent introduces an intermediary inspection region between the source wire and the pixel electrode forming region. This intermediary zone serves as a detection buffer that enhances the visibility of pattern defects during optical inspection, allowing defects to be detected with high contrast even when using a simplified five-step manufacturing 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
This approach reduces manufacturing costs and improves the detection rate of cross talk point defects, ensuring higher yield and quality by increasing the brightness difference between normal and pattern defect spots during inspection.
Implementation Method 1
light is applied onto pixel patterns arranged periodically, pieces of reflected light thereof are compared with one another at the same spot of three or more pixel patterns, and a spot different in brightness from those of other pixel patterns is detected as the position of the pattern defect
Data Source
AI summary
Source wires having a semiconductor film thereunder are formed wide within a range that does not overlap pixel electrodes formed later. Thereafter, a resist pattern for use in patterning the pixel electrodes is formed so as to overlap edge portions of the source wires, and etching using the resist pattern as a mask is performed, whereby the pixel electrodes are formed, and in addition, the edge portions of the source wires are removed, whereby a structure in which the semiconductor film has a portion projecting beyond the source wires on both sides is formed.