Three-Mask TFT Fabrication for LCD Electrode Alignment
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Solution Overview
Problem
The complex manufacturing process of thin film transistor substrates in liquid crystal display devices, particularly in fringe field switching type, leads to increased costs and complexity due to the requirement of multiple mask processes, including semiconductor processes.
Innovation Solution
A simplified process for fabricating a thin film transistor substrate using a three-mask process approach, where the gate line and common line are formed with a first conductive layer group having at least double conductive layers, and the data line, source electrode, and drain electrode are formed with a second conductive layer group, allowing for step coverage and reduced material costs through the use of transparent and metal conductive layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple mask processes are used to form gate line, common line, data line, source electrode, drain electrode, and pixel electrode separately, then the liquid crystal display device can be fabricated with proper electrode alignment and structure, but the manufacturing process becomes complex and costly
Solution Approach 1:
The patent combines the formation of gate line and common line into a single first mask process using a first conductive layer group, and combines the formation of data line, source electrode, and drain electrode into a single second mask process using a second conductive layer group. This merging of multiple electrode formations into fewer mask processes reduces manufacturing complexity while maintaining proper electrode alignment through the conductive layer group structure.
Solution Approach 2:
The first conductive layer group serves multiple functions by forming both the gate line and common line, while the second conductive layer group serves multiple functions by forming the data line, source electrode, and drain electrode. This multi-functionality approach allows a single mask process to accomplish what previously required multiple separate processes, thereby simplifying the overall manufacturing process.
2Manufacturing precision
If multiple mask processes including semiconductor processes are used, then the electrodes can be properly formed and aligned, but the manufacturing cost increases
Solution Approach 1:
The patent merges the formation of multiple electrodes into two main mask processes instead of requiring separate semiconductor processes for each electrode. The first mask process forms gate line and common line, while the second mask process forms data line, source electrode, and drain electrode. This consolidation reduces the number of expensive semiconductor processing steps required.
Solution Approach 2:
The patent changes the manufacturing approach by using conductive layer groups with different transparency parameters - the first conductive layer group includes a transparent conductive layer for electrodes requiring light transmission, while the second conductive layer group includes a metal conductive layer for electrodes where electrical conductivity is prioritized. This parameter-based classification allows optimized electrode formation with reduced process complexity and cost.
Data Source
AI summary
A fringe field switching thin film transistor substrate includes a gate electrode connected to the gate line, a source electrode connected to the data line, a drain electrode opposed to the pixel electrode and a semiconductor layer defining a channel between the source electrode and the drain electrode. A common electrode extends from the common line into the pixel area. A pixel electrode extends from the drain electrode into the pixel area overlapping the common electrode with the gate insulating film. The gate line and the common line are formed from a first conductive layer group having double conductive layers, and the common electrode is formed by an extension of the lowermost layer of the common line. The data line, the source electrode and the drain electrode are formed of a second conductive layer group having double conductive layers.