Polyimide Film Wet Planarization for Lithography
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Solution Overview
Problem
Polyimide films in semiconductor devices exhibit rugged surface topography and high reflection index, leading to deformation of photo-resist patterns during photolithography, which deteriorates the performance of subsequent processes.
Innovation Solution
A method involving a wet planarization process using agents like N-methylpyrrolidone and other solvents to smooth the polyimide film surface, followed by patterning with a photo-resist layer and etching, and the use of anti-reflective coatings to improve pattern fidelity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a photo-resist layer is formed directly on a polyimide film with rugged surface topography, then the photolithography process can be performed, but the photo-resist pattern deforms after development
Solution Approach 1:
The patent applies wet planarization treatment to the polyimide film surface before forming the photo-resist layer. This preliminary action smooths the rugged surface topography in advance, creating a flat substrate that prevents subsequent photo-resist pattern deformation during photolithography and development processes.
Solution Approach 2:
The patent introduces an anti-reflective coating (BARC) layer as an intermediary between the polyimide film and the photo-resist layer. This intermediate layer serves dual functions: it further planarizes the surface and reduces light reflection, thereby preventing photo-resist pattern deformation and improving lithography performance.
2Reliability
If a polyimide film with high reflection index is used, then the film provides good insulating properties, but light reflection causes photo-resist pattern deformation
Solution Approach 1:
The patent introduces an anti-reflective coating (BARC) layer as an intermediary between the polyimide film and the photo-resist layer. This intermediate layer serves dual functions: it further planarizes the surface and reduces light reflection, thereby preventing photo-resist pattern deformation and improving lithography performance.
Solution Approach 2:
The patent converts the high reflection property of the polyimide film, which is normally harmful, into a beneficial characteristic by using it as a basis for forming the anti-reflective coating. The BARC layer is specifically designed to address the reflection issue, transforming the problematic high reflection index into an opportunity for improved process control through targeted coating application.
3Manufacturing precision
If wet planarization process is performed before photolithography, then photo-resist pattern deformation is prevented, but additional process steps are required
Solution Approach 1:
The patent combines the wet planarization treatment with the existing photolithography process flow by integrating it as a preparatory step before photo-resist coating. The planarization process uses standard wet chemical treatments and drying procedures that are already part of the semiconductor fabrication toolkit, merging the new requirement with existing process capabilities.
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
The method results in a polyimide film with reduced surface topographical differences, preventing photo-resist deformation and enhancing the yield and performance of photolithography and subsequent processes in semiconductor device fabrication.
Implementation Method 1
A wet planarization process is then performed to remove a portion of the polyimide film. Subsequently the planarized polyimide film is patterned.
Implementation Method 2
the pattern of a photo-resist which is formed on the polyimide film may be deformed after a development step is carried out during a photolithography process
Implementation Method 3
providing a bottom anti-reflective coating (BARC) layer disposed between the planarized polyimide film and the patterned photo-resist layer
Data Source
AI summary
A method for fabricating a patterned polyimide film, wherein the method comprises steps as follows: Firstly, a polyimide film is provided on a substrate. A wet planarization process is then performed to remove a portion of the polyimide film. Subsequently the planarized polyimide film is patterned.