Active Matrix Substrate Reducing Photolithography Steps
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Solution Overview
Problem
The production of active matrix substrates for display devices, particularly those using thin film transistors (TFTs), faces challenges in reducing the number of photolithography processes, which increases production costs and complexity, especially when using oxide semiconductors that are prone to etching issues with common metal films.
Innovation Solution
The proposed solution involves an active matrix substrate design with a thin film transistor structure that includes a semiconductor film, source and drain electrodes, a channel part, an insulation film, and a gate electrode, where the source, drain, and source line electrodes are made from the same conductive layer as the pixel electrode, and the semiconductor layer remains under these components, reducing the number of photolithography processes required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide semiconductor is used for the active layer to improve mobility and display performance, then display performance is improved, but the oxide semiconductor is easily dissolved by acid-based etching solutions used for metal films, causing manufacturing complexity to increase
Solution Approach 1:
A barrier layer is introduced between the oxide semiconductor active layer and the metal film to prevent direct contact during etching processes. This intermediary layer allows acid-based etching solutions to remove metal films without dissolving the oxide semiconductor, thus maintaining manufacturing process simplicity while preserving display performance.
Solution Approach 2:
The etching selectivity is optimized by controlling the film thickness ratio between the barrier layer and the metal film. By setting the barrier layer thickness to be greater than the metal film thickness, the etching process selectively removes the metal film while protecting the oxide semiconductor underneath, resolving the contradiction between performance and manufacturing complexity.
2Manufacturing precision
If multiple photolithography processes are used to form pixel electrodes and opposite electrode separately, then electrode formation precision is improved, but the number of manufacturing steps increases, reducing productivity
Solution Approach 1:
The pixel electrode and opposite electrode are formed simultaneously in a single photolithography process by using a conductive layer that is patterned to create both electrodes at different locations. This merging of operations maintains electrode formation precision while significantly reducing the number of manufacturing steps and improving productivity.
Solution Approach 2:
A single conductive layer serves multiple functions by being patterned to form both the pixel electrode and the opposite electrode. This multi-functional approach eliminates the need for separate conductive layers and photolithography processes for each electrode, thereby increasing production efficiency without sacrificing precision.
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 simplifies the manufacturing process, reduces production costs, and enhances the performance of the active matrix substrate by allowing for the use of oxide semiconductors while maintaining the integrity of the semiconductor layer during etching.
Implementation Method 1
the above-described oxide semiconductors can be etched with a weak acid solution such as oxalic acid and carboxylic acid
Implementation Method 2
a plasma treatment is performed to perform etching
Implementation Method 3
a photoresist pattern forming step, an organic solvent developing step, and a photoresist stripping step
Data Source
AI summary
The present disclosure relates to a method for manufacturing an active matrix substrate. A first laminated film in which a semiconductor film, a first transparent conductive film, and a first metal film are laminated is formed on a substrate. A photoresist pattern having a first part covering a formation area of a channel part of a thin film transistor, a second part covering a formation area of a pixel electrode, and a third part covering formation areas of a source electrode, a drain electrode, and a source line, is formed on the first laminated film. The first metal film, the first transparent conductive film, and the semiconductor film are patterned using the photoresist pattern; the first part is removed and the first metal film and the first transparent conductive film are patterned; and the second part is removed and the first metal film is patterned.