Topcoat Layer for Liquid Immersion Lithography Defect Control
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Solution Overview
Problem
In liquid immersion lithography processes, existing methods face challenges in preventing photoresist film component elution and pattern defects due to liquid immersion liquid droplets on the photoresist film, leading to watermark and residue defects.
Innovation Solution
A resist pattern-forming method involving the application of a photoresist composition on a substrate, followed by a topcoat layer lamination, liquid immersion lithography with partial topcoat removal before development, to inhibit watermark and residue defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a topcoat layer is provided between the photoresist film and the liquid immersion liquid, then the elution of photoresist film components is inhibited and pattern defects are reduced, but the process complexity increases due to additional lamination and removal steps
Solution Approach 1:
The topcoat layer is applied in advance before liquid immersion lithography to prevent photoresist component elution and pattern defects. This preliminary protective action ensures pattern quality is maintained throughout the lithography process, addressing the reliability improvement while accepting the necessary process complexity
Solution Approach 2:
The topcoat layer is temporarily applied to protect the photoresist film during lithography, then selectively removed after exposure. This temporary protective measure allows the topcoat to serve its protective function during the critical lithography step while being discarded afterward to avoid interfering with subsequent processing steps
2Manufacturing precision
If liquid immersion lithography is performed with a topcoat layer, then watermark and residue defects are reduced, but the manufacturing time increases due to additional processing steps
Solution Approach 1:
The topcoat layer is applied beforehand to prevent watermark and residue defects during liquid immersion lithography. This preliminary protective measure ensures high pattern precision by preventing defect formation during the exposure process, with the understanding that additional time is required for the lamination and subsequent removal steps
Solution Approach 2:
The topcoat layer serves as an intermediary between the liquid immersion liquid and the photoresist film, preventing direct harmful interactions that cause watermark and residue defects. This intermediary layer protects the photoresist while allowing the lithography process to proceed with high precision
Data Source
AI summary
A resist pattern-forming method includes applying a photoresist composition directly or indirectly on a front face of a substrate to form a photoresist film. A topcoat layer is laminated directly or indirectly on a front face of the photoresist film. The photoresist film is subjected to liquid immersion lithography in a presence of a liquid immersion liquid on a front face of the topcoat layer. Part of the topcoat layer is removed after subjecting the photoresist film to the liquid immersion lithography. The photoresist film is developed after the part of the topcoat layer is removed.