Resist Film Planarization via Spatial Exposure Control
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Solution Overview
Problem
Conventional planarizing methods face challenges in achieving high flatness due to variations in film thickness distribution in the resist film, which complicates the reduction of steps and uniformity in the planarized film, especially when using the etch-back method.
Innovation Solution
A method involving forming a resist film with controlled thickness distribution by exposing different sections of the film to varying amounts of light, followed by development and etching to achieve uniform film thickness, utilizing techniques like ion milling and employing gray-tone or half-tone masks to optimize exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a uniform exposure amount is applied to the entire resist film, then the exposure process is simple, but the film thickness distribution in the planarized film cannot be controlled to match substrate variations
Solution Approach 1:
The patent applies different exposure amounts to different sections of the resist film based on the substrate's step distribution. By making the exposure condition local rather than uniform, the resist film thickness after development can be precisely controlled in each section to compensate for substrate variations, thereby achieving high flatness planarization.
Solution Approach 2:
The patent divides the substrate area into multiple sections and applies different exposure amounts to each section. This segmentation allows independent control of resist film thickness in each region, enabling precise matching of the resist film profile to the substrate's topography variations.
2Object-affected harmful factors
If the resist film thickness is increased to cover larger steps, then better coverage is achieved, but the distribution of film thickness in the resist film becomes more significant
Solution Approach 1:
The patent changes the exposure amount parameter across different sections of the resist film to control the developed film thickness distribution. By adjusting exposure parameters locally, the method achieves both adequate step coverage and controlled thickness uniformity, eliminating the trade-off between these two requirements.
3Ease of manufacture
If conventional etch-back method is used, then the process is simple, but the step reduction is limited by the resist film thickness distribution
Solution Approach 1:
The patent performs preliminary exposure with spatially varying amounts before etching, to pre-shape the resist film thickness distribution. This preliminary action creates a resist profile that precisely matches the required etch depth variation, enabling greater step reduction capability while maintaining process simplicity.
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 allows for high-flatness planarization by adjusting the resist film thickness to match the target film's variations, resulting in a uniformly planarized film with reduced thickness variations, as demonstrated in practical examples.
Implementation Method 1
exposing the resist film with the amounts of exposure light in respective sections into which an area is divided
Implementation Method 2
etching the resist film pattern and the film to be planarized, until eliminating the thickness amounts to be eliminated of the film to be planarized
Data Source
AI summary
Provided is a planarizing method in which a planarization with high flatness can be performed, without being restricted by the distribution of film thickness in the applied resist film. The planarizing method comprises the steps of: forming a resist film on a film to be planarized formed on a substrate; exposing the resist film with the amounts of exposure light in respective sections into which an area in which the film to be planarized is formed is divided, the amounts of exposure light being determined so as to realize film thicknesses to be left for planarization of the resist film in the respective sections; developing the exposed resist film, to form a resist film pattern with a controlled distribution of film thickness; and etching the resist film pattern and the film to be planarized, until eliminating the thickness amounts to be eliminated of the film to be planarized.