Degassed Liquid Film Processing for Bubble-Free Supercritical Drying
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Solution Overview
Problem
In semiconductor device manufacturing, existing substrate processing methods face challenges in preventing pattern collapse during supercritical drying due to bubble formation from dissolved gases in processing liquids, which can damage the surface of wafers with intricate patterns.
Innovation Solution
A substrate processing method that involves removing dissolved gases from the processing liquid, forming a liquid film on the substrate, and then using a processing fluid in a supercritical state to replace and vaporize the liquid, while maintaining an inert gas atmosphere to minimize gas dissolution and bubble formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a processing liquid is supplied onto the substrate surface for cleaning, then the substrate surface is cleaned effectively, but dissolved gases in the processing liquid form bubbles during supercritical drying causing pattern collapse
Solution Approach 1:
The patent applies preliminary action by removing dissolved gases from the processing liquid before it contacts the substrate. The degassing unit eliminates bubbles and dissolved gases in advance, preventing pattern collapse during subsequent supercritical drying while maintaining effective cleaning
Solution Approach 2:
The patent extracts the harmful dissolved gases from the processing liquid through a degassing unit before the liquid is supplied to the substrate. This separation removes the bubble-forming components while retaining the cleaning functionality of the processing liquid
2Reliability
If the substrate is dried using conventional methods, then the processing is simple, but particle generation occurs and pattern collapse happens
Solution Approach 1:
The patent changes the physical parameters of the drying system by using supercritical fluid conditions (high pressure and temperature) instead of conventional atmospheric drying. This parameter change enables particle-free drying while preventing pattern collapse, despite increasing system complexity
Solution Approach 2:
The patent introduces a supercritical fluid as an intermediary medium between the processing liquid and the dried substrate. This intermediary replaces the processing liquid without causing bubble formation or particle generation, ensuring reliable drying
3Object-affected harmful factors
If dissolved gases are removed from the processing liquid, then bubble formation is suppressed, but additional processing steps are required
Solution Approach 1:
The degassing operation is performed in advance before substrate processing, eliminating dissolved gases from the processing liquid. This preliminary action suppresses bubble formation during subsequent steps while the system is prepared for efficient batch processing
Solution Approach 2:
The patent combines multiple functions into integrated units: the degassing unit is merged with the liquid supply system, and the supercritical drying unit combines drying with particle removal. This merging reduces overall processing steps while maintaining high productivity
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 effectively suppresses pattern collapse during supercritical drying by reducing bubble formation and ensuring the integrity of high-aspect-ratio patterns on the substrate surface.
Implementation Method 1
drying the surface of the substrate by flowing a processing fluid into the processing vessel while maintaining an internal pressure of the processing vessel, in which the substrate having the liquid film formed thereon is accommodated, at a pressure allowing the processing fluid to be maintained in a supercritical state, to replace the processing liquid covering the surface of the substrate with the processing fluid, and, then, by vaporizing the processing fluid
Implementation Method 2
maintaining an internal pressure of the processing vessel, in which the substrate having the liquid film formed thereon is accommodated, at a pressure allowing the processing fluid to be maintained in a supercritical state
Data Source
AI summary
A substrate processing method includes removing a dissolved gas in a processing liquid; forming a liquid film of the processing liquid covering a surface of a substrate, by supplying, onto the surface of the substrate, the processing liquid from which the dissolved gas is removed; carrying the substrate having the liquid film formed thereon into a processing vessel; and drying the surface of the substrate by flowing a processing fluid into the processing vessel while maintaining an internal pressure of the processing vessel, in which the substrate having the liquid film formed thereon is accommodated, at a pressure allowing the processing fluid to be maintained in a supercritical state, to replace the processing liquid covering the surface of the substrate with the processing fluid, and, then, by vaporizing the processing fluid.