Wafer Drying Liquid with Fluorine Compounds
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Solution Overview
Problem
As semiconductor wafers with decreasing feature sizes and increasing diameters experience pattern collapse during drying due to high aspect ratios and surface tension, existing techniques for preventing pattern collapse are ineffective and often leave residues.
Innovation Solution
A method involving a rotary chuck with a heating assembly and a drying liquid comprising greater than 50% organic solvent, such as isopropyl alcohol, and a fluorine-containing compound like hydrofluoric acid, which is applied to the wafer while being heated to a temperature of 30-300°C, preventing pattern collapse by rapid evaporation and avoiding residue formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional drying techniques are used on semiconductor wafers with high aspect ratio features, then the drying process can be completed, but pattern collapse occurs due to surface tension forces
Solution Approach 1:
The patent changes the chemical composition parameters of the drying liquid by incorporating fluorinated compounds (such as fluorinated alcohols or fluorinated hydrocarbons) which have significantly lower surface tension than conventional drying liquids. This parameter change in liquid composition directly reduces the surface tension forces acting on the wafer features, preventing pattern collapse while maintaining effective drying capability
Solution Approach 2:
The patent uses composite drying liquids that combine fluorinated compounds with conventional solvents or additives. This composite approach leverages the low surface tension properties of fluorinated compounds while maintaining the beneficial drying characteristics of established liquids, achieving both pattern collapse prevention and effective drying
2Productivity
If the diameter of semiconductor wafers is increased to accommodate more device features, then production capacity increases, but pattern collapse becomes more severe due to higher aspect ratios
Solution Approach 1:
By changing the surface tension parameter of the drying liquid through fluorinated compound addition, the patent enables effective drying of large diameter wafers (200mm, 300mm, or larger) without pattern collapse. The reduced surface tension allows the liquid to be removed from high aspect ratio features even on oversized wafers, thus supporting increased productivity while maintaining pattern integrity
3Manufacturing precision
If existing pattern collapse prevention techniques are applied, then some protection is provided, but residues are left on the wafer surface that impair device performance
Solution Approach 1:
The patent changes the chemical composition to use fluorinated compounds which possess both low surface tension and high volatility. These properties enable the drying liquid to prevent pattern collapse during drying while evaporating completely without leaving residues on the wafer surface, thus eliminating the residue problem associated with conventional prevention techniques
Solution Approach 2:
The patent employs a drying liquid designed to be temporarily present during the drying process and then completely evaporate. The fluorinated compounds used are highly volatile and leave no persistent residue, effectively making the drying liquid a temporary, disposable medium that performs its function and then disappears without contamination
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 effectively prevents pattern collapse and residue formation on semiconductor wafers by using a heated drying liquid with a high organic solvent content and fluorine-containing compounds, ensuring efficient drying without impairing device performance.
Implementation Method 1
During at least part of the dispensing step, the wafer-shaped article is heated with a heating assembly
Implementation Method 2
preventing pattern collapse by rapid evaporation
Data Source
AI summary
A method for drying wafer-shaped articles comprises rotating a wafer-shaped article of a predetermined diameter on a rotary chuck, and dispensing a drying liquid onto one side of the wafer-shaped article. The drying liquid comprises greater than 50 mass % of an organic solvent. During at least part of the dispensing step, the wafer-shaped article is heated with a heating assembly. During at least part of the dispensing step a fluorine-containing compound is present in the drying liquid or in a gas that surrounds the drying liquid as the drying liquid contacts the wafer-shaped article.