Substrate Processing Method for High-Aspect-Ratio Pattern Collapse Prevention
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Solution Overview
Problem
Fine patterns with high aspect ratios on substrates are prone to collapse during the drying process due to surface tension, especially when using organic solvents, as they have lower surface tension than water, leading to pattern collapse and defects in semiconductor and other device fabrication.
Innovation Solution
A substrate processing method involving a liquid film formation, partial elimination of the liquid film to create a liquid film-removed region, enlargement of this region, and maintaining a hydrogen fluoride atmosphere at the liquid film boundary to decompose silicon oxides and reduce adhesion, combined with heating the processing liquid to accelerate evaporation and residue removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If organic solvent is supplied to replace water in the spin drying step, then pattern collapse due to surface tension is reduced, but fine patterns with high aspect ratios still collapse due to the liquid surface forming in the pattern
Solution Approach 1:
The patent applies preliminary action by performing a chemical modification step before the spin drying step. Specifically, silicon oxide is formed on the substrate surface prior to drying, and this silicon oxide layer is designed to prevent adhesion between the liquid surface and the pattern during subsequent drying operations. This preliminary preparation eliminates the harmful surface tension effect before it can cause pattern collapse.
Solution Approach 2:
The patent introduces silicon oxide as an intermediary substance between the liquid surface and the pattern. This intermediary layer prevents direct contact and adhesion between the liquid and the pattern structure, thereby eliminating the surface tension-induced collapse while still allowing effective drying to occur.
2Productivity
If high-speed rotation is applied in the spin drying step, then water is removed effectively, but the liquid surface forms in the pattern causing collapse of fine patterns with high aspect ratios
Solution Approach 1:
The patent performs the silicon oxide formation step before the high-speed spin drying operation. This preliminary action prepares the surface to withstand the harsh drying conditions without suffering from pattern collapse, enabling high-speed rotation to be used effectively for water removal.
Solution Approach 2:
The silicon oxide layer serves as a protective intermediary that allows high-speed rotation to proceed without causing pattern collapse. The intermediary layer absorbs or mitigates the harmful effects of the liquid surface tension during high-speed drying, enabling both high productivity and pattern integrity.
3Ease of manufacture
If water is supplied to replace chemical liquid, then rinsing is achieved, but water remains in the pattern interior requiring additional organic solvent step
Solution Approach 1:
The patent extracts or removes water from the pattern interior more effectively by using the silicon oxide-modified surface during the spin drying process. The modified surface prevents water from adhering to the pattern, allowing water to be removed more completely and reducing or eliminating the need for additional organic solvent rinsing steps.
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
Effectively reduces pattern collapse and enables dry surface processing by preventing silicon oxides from adhering to the pattern tips, allowing the pattern to stand up and dry without defects, even with high-aspect-ratio features.
Implementation Method 1
maintaining a hydrogen fluoride atmosphere at the liquid film boundary to decompose silicon oxides and reduce adhesion
Implementation Method 2
heating the processing liquid to accelerate evaporation and residue removal
Implementation Method 3
surface tension of the liquid acts at the contact position between the liquid surface and the pattern. The surface tension is one cause of collapse of the pattern
Data Source
AI summary
A substrate processing method includes a substrate holding step of horizontally holding a substrate, a liquid film forming step of supplying a processing liquid onto the upper surface of the substrate to form a liquid film of the processing liquid covering the upper surface of the substrate, a liquid film-removed region-forming step of partially eliminating the processing liquid from the liquid film of the processing liquid to form a liquid film-removed region in the liquid film of the processing liquid, a liquid film-removed region enlarging step of enlarging the liquid film-removed region toward the outer periphery of the substrate, and a hydrogen fluoride atmosphere-holding step of keeping the ambient atmosphere at the boundary between the liquid film-removed region and the liquid film of the processing liquid as an atmosphere of hydrogen fluoride-containing vapor, in parallel with the liquid film-removed region enlarging step.