U-Shaped Electrode Design for Reliable TFT Manufacturing
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Solution Overview
Problem
The existing manufacturing methods for thin film transistors in display devices often result in recessed or separated electrode connections due to insufficient coverage of the photoresist film during the reflow process, leading to unreliable electrode formation.
Innovation Solution
A method is developed where the electrodes are formed in a U-shape with a projecting portion that functions as a connecting point, using a deformed photoresist film as a mask to ensure complete coverage and prevent separation, allowing for reliable etching of the semiconductor layer and formation of stable electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the photoresist film is made to reflow to form a mask for selectively etching the semiconductor layer, then the number of photolithography steps can be reduced, but the photoresist film does not sufficiently cover the outer end portion of the electrode connecting portion, resulting in incomplete mask formation and electrode separation
Solution Approach 1:
A projecting portion is formed on the electrode connecting portion before the photoresist reflow process. This preliminary structural modification ensures that when the photoresist film reflops, it has sufficient material to cover the entire connecting portion including the outer end portion, preventing mask formation failures and electrode separation while maintaining the reduced step count benefit
2Ease of manufacture
If the photoresist film is made to reflow, then the manufacturing process is simplified, but a recessed portion is formed at the connecting portion of parallel conductor layers, potentially separating the electrodes
Solution Approach 1:
The projecting portion is formed in advance on the electrode connecting portion before the reflow process. This preliminary action compensates for the material that would otherwise be lost during reflow, ensuring that the photoresist film can form a complete, continuous mask without creating recessed portions that would compromise electrode connection integrity
Solution Approach 2:
The projecting portion acts as a cushion or reserve material that prevents the formation of recessed portions during the photoresist reflow process. By having extra material at the connecting portion beforehand, the reflow process can proceed with simplified steps while the projecting portion ensures sufficient photoresist coverage is maintained, preventing electrode separation
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 ensures reliable electrode formation by ensuring the photoresist film adequately covers the electrode ends, preventing recesses and separation, thus enhancing the manufacturing process for thin film transistors in display devices.
Implementation Method 1
a photoresist film formed on upper surfaces of these electrodes is made to remain, and the photoresist film is made to reflow to form a photoresist film (a modified photoresist film) which constitutes a mask
Data Source
AI summary
A display device includes a sequentially stacked body formed of a gate signal line, an insulation film, a semiconductor layer and a conductor layer on a substrate. The conductive layer forms a drain electrode and a source electrode of a thin film transistor which are arranged with a channel region of the semiconductor layer therebetween, and one of the drain and source electrode is formed in an approximately U shape having an open-ended one end side and a connecting portion on another end side so that the one electrode surrounds a distal end portion of another electrode as viewed in a plan view, and a projecting portion is formed on a side of the connecting portion opposite to the another electrode.