Thin Film Transistor Substrate Dual Etch Stop Layer Protection
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Solution Overview
Problem
Thin film transistor substrates face deterioration in switching characteristics due to defects in the channel part caused by etching processes, leading to suboptimal performance.
Innovation Solution
A thin film transistor substrate design incorporating a first and second etch stop pattern with different materials and thicknesses, where the second etch stop pattern overlaps the channel area and the first etch stop pattern covers it, along with a method of manufacturing involving specific etching processes to prevent channel part defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an etch stop layer is etched using an etchant to form an etch stop pattern, then the etch stop pattern can be formed to cover the channel part, but defects may occur in the channel part and switching characteristic deteriorates
Solution Approach 1:
The patent divides the single etch stop layer into two separate etch stop layers (first etch stop layer and second etch stop layer) with different materials. This segmentation allows selective etching of the second layer without damaging the channel part, while the first layer continues to protect the channel part. The two-layer structure resolves the contradiction by separating the protective function from the pattern formation function.
Solution Approach 2:
The first etch stop layer acts as an intermediary protective layer between the channel part and the etching process. When the second etch stop layer is etched away, the first etch stop layer remains to cover and protect the channel part from etchant damage. This intermediary layer enables the etching process to proceed without compromising the channel part integrity.
2Reliability
If the etch stop layer is made thicker to better cover the channel part, then protection is improved, but etching defects still occur and switching characteristic deteriorates
Solution Approach 1:
The patent applies local quality by using different materials for the first and second etch stop layers. The second etch stop layer (with higher etch selectivity) is used where pattern formation is needed, while the first etch stop layer (with appropriate thickness and material properties) provides localized protection over the channel part. This local differentiation of material properties allows simultaneous achievement of protection and defect-free etching.
Data Source
AI summary
In a method of manufacturing a thin film transistor substrate, a semiconductor pattern is formed on a substrate, a first etch stop layer and a second etch stop layer are sequentially formed on the semiconductor pattern, and the second etch stop layer and the first etch stop layer are sequentially patterned to form a second etch stop pattern and a first etch stop pattern. Thus, when the second etch stop layer is patterned using an etchant, the first etch stop layer covers the semiconductor pattern, thereby preventing the semiconductor pattern from being etched by the etchant.