Thin-Film Transistor Substrate Hard Mask Contact Hole Precision
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Solution Overview
Problem
The challenge in achieving high-definition organic electroluminescent devices is the expansion of contact holes created by ordinary exposure technologies, making it difficult to maintain the required precision for high-definition performance.
Innovation Solution
A thin-film transistor substrate is designed with a hard mask metal having openings that define the size of contact holes on an interlayer insulating film, allowing for precise reduction in contact hole size and enabling the achievement of high-definition organic electroluminescent devices, while also reducing the number of masks needed in the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ordinary exposure technology is used to provide contact holes on an interlayer insulating film, then the manufacturing process is simple, but the contact holes expand in size making it difficult to achieve high-definition performance
Solution Approach 1:
The mask structure is segmented into multiple functional layers: a lower mask layer (interlayer insulating film) and an upper hard mask metal layer. This segmentation allows each layer to perform its specific function - the lower layer provides insulation and initial patterning, while the upper layer maintains precise contact hole dimensions during etching, thereby resolving the contradiction between manufacturing precision and device complexity.
Solution Approach 2:
The interlayer insulating film is formed and patterned in advance before the hard mask metal is deposited. This preliminary action creates a prepared substrate that guides the subsequent contact hole formation, allowing the hard mask metal to be precisely positioned and ensuring accurate contact hole dimensions are maintained throughout the etching process.
2Manufacturing precision
If contact hole size is reduced for high-definition devices, then definition is improved, but hydrogen supply to transistors increases affecting device reliability
Solution Approach 1:
The interlayer insulating film acts as an intermediary barrier between the contact holes and the transistor. It selectively blocks hydrogen migration from the contact hole regions to the transistor channels, thereby protecting transistor performance while allowing small contact holes to be formed for high-definition display requirements.
Solution Approach 2:
The interlayer insulating film provides localized protection specifically at the transistor regions beneath the contact holes. This local quality approach allows hydrogen blocking where needed (at transistor locations) while maintaining electrical connectivity where required (through the contact holes), thus resolving the contradiction between small contact hole size and transistor reliability.
Data Source
AI summary
A thin-film transistor substrate includes a pixel circuit, an interlayer insulating film, electrodes, and a hard mask metal. The pixel circuit includes a thin film transistor. The interlayer insulating film has contact holes and covers the pixel circuit. The electrodes are exposed above a surface of the interlayer insulating film, and electrically coupled to the pixel circuit via the contact holes. The hard mask metal has openings at portions facing the contact holes and is provided on the surface of the interlayer insulating film.