Coating Method Liquid Film Backside Mist Prevention
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Solution Overview
Problem
The existing resist coating methods for semiconductor wafers result in significant solvent consumption due to the scattering of resist mist, which requires extensive backside cleaning, leading to high organic solvent usage and inefficiencies in the coating process.
Innovation Solution
A coating apparatus and method that incorporates a liquid film forming mechanism and posture regulating mechanism to prevent mist deposition on the substrate's backside by forming a liquid film using a process liquid with surface tension, reducing the need for solvent cleaning and minimizing solvent consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If spin coating is performed to form a resist film, then the resist is spread uniformly on the substrate, but mist is scattered and deposited on the back side peripheral portion of the substrate
Solution Approach 1:
The patent introduces a liquid film forming mechanism that uses a process liquid to create a liquid film on the back side of the substrate. This liquid film acts as a barrier that captures and removes mist particles that would otherwise be deposited on the substrate back side, converting the harmful mist scattering into a controllable cleaning process
Solution Approach 2:
The patent introduces a process liquid as an intermediary substance between the mist and the substrate back side. The process liquid forms a liquid film that mediates the interaction by capturing mist particles and preventing their direct deposition on the substrate, thereby solving the mist deposition problem
2Reliability
If a back side cleaning step is performed to remove mist, then particle contamination is prevented, but solvent consumption increases significantly
Solution Approach 1:
The liquid film forming mechanism enables the system to self-clean the substrate back side by forming a liquid film that naturally captures and removes mist particles through the rotation of the substrate, eliminating the need for extensive solvent-based cleaning steps
Solution Approach 2:
The patent changes the state of the cleaning process from using large amounts of solvent to using a minimal amount of process liquid that forms a film. This parameter change from bulk liquid cleaning to film-based cleaning dramatically reduces solvent consumption while maintaining effective particle removal
3Productivity
If the substrate is rotated at high speed to spread coating liquid, then film formation is efficient, but mist scattering increases
Solution Approach 1:
The patent segments the coating process into two distinct zones: the front side where high-speed rotation efficiently spreads the coating liquid, and the back side where the liquid film mechanism operates to capture mist. This spatial segmentation allows high-speed rotation to be used for efficient film formation without excessive mist deposition problems
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 solution effectively reduces solvent consumption by preventing mist deposition on the substrate's backside, enhancing the efficiency of the coating process and minimizing particle contamination, thereby reducing the overall solvent usage and improving the uniformity of the resist film formation.
Implementation Method 1
a process liquid supply portion for supplying the process liquid onto the counter face portion, so that the process liquid is adsorbed by its surface tension on the counter face portion and the peripheral portion of the substrate being rotated and the liquid film is thereby formed
Implementation Method 2
The coating liquid is supplied on the front side central portion of the substrate, and the spin chuck is rotated about a vertical axis, so that the coating liquid is spread toward the peripheral portion of the substrate or wafer by a centrifugal force
Data Source
AI summary
A coating method includes supplying a coating liquid from a coating nozzle onto a front side central portion of a substrate held on a substrate holding member, rotating the substrate holding member about a vertical axis to spread the coating liquid toward a peripheral portion of the substrate by a centrifugal force and thereby form a film of the coating liquid, forming a liquid film of a process liquid for preventing a contaminant derived from the coating liquid from being deposited or left on a back side peripheral portion of the substrate, and damping a vertical wobble of the peripheral portion of the substrate being rotated, by a posture regulating mechanism, while delivering a gas from delivery holes onto a back side region of the substrate on an inner side of the peripheral portion on which the liquid film is formed.