Wafer Drying via Solvent Displacement and Hydrophobicity Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for drying semiconductor wafers, such as using IPA or HFE/HFC solvents, often result in pattern collapse due to surface tension issues and poor hydrophobization, leading to inefficiencies in removing deionized water and water-repellent agents.
Innovation Solution
A liquid processing method involving sequential supply of deionized water, a first solvent (isopropyl alcohol) to replace the water, a water-repellent agent (trimethylsilyl dimethylamine) to impart hydrophobicity, and a second solvent (hydrofluoroolefin) with higher boiling point and specific gravity, which efficiently removes the water-repellent agent by leveraging differences in specific gravity and solubility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common solvent (IPA, HFE, or HFC) is supplied before and after the hydrophobizing agent, then the process is simple, but the water-repellent effect is insufficient and pattern collapse occurs
Solution Approach 1:
The drying process is divided into three distinct stages: (1) first solvent supply to replace deionized water, (2) hydrophobizing agent supply to impart water-repellency, and (3) second solvent supply to remove the hydrophobizing agent. This segmentation allows each stage to use optimally suited solvents, achieving both process effectiveness and reasonable complexity
Solution Approach 2:
The invention changes the solvent parameters (specific gravity and chemical properties) between stages. The first solvent has lower specific gravity than the hydrophobizing agent, while the second solvent has higher specific gravity, enabling effective displacement and removal based on density differences and solubility characteristics
2Productivity
If deionized water is simply shaken off by rotating the wafer, then the process is quick, but pattern collapse occurs due to surface tension
Solution Approach 1:
The first solvent (IPA or HFE/HFC) acts as an intermediary substance that replaces deionized water on the wafer surface before drying. This intermediary solvent has appropriate surface tension characteristics that prevent pattern collapse while allowing quick removal, thus protecting the pattern during the drying process
Solution Approach 2:
The invention utilizes phase transitions of the first solvent (evaporation or rapid removal) to achieve quick drying while maintaining pattern integrity. The solvent transitions from liquid state on the wafer surface to vapor state, removing water effectively without causing pattern collapse
3Reliability
If the hydrophobizing agent is not removed after treatment, then the water-repellent effect is maintained, but particle contamination occurs and the process is incomplete
Solution Approach 1:
The second solvent is specifically selected to extract and remove the hydrophobizing agent from the wafer surface after the water-repellent effect has been established. This extraction process removes potential particle contamination sources while preserving the hydrophobic modification on the wafer surface
Solution Approach 2:
The second solvent has higher specific gravity than the hydrophobizing agent, enabling effective displacement and removal based on density differences. This parameter change ensures complete removal of the hydrophobizing agent without compromising the water-repellent effect
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 method quickly achieves a dried substrate with reduced pattern collapse risk by effectively removing deionized water and water-repellent agents, enhancing hydrophobicity and preventing particle contamination.
Implementation Method 1
supplying a first solvent to the front surface of the substrate after supplying the deionized water
Implementation Method 2
A specific gravity of the first solvent is smaller than a specific gravity of the water-repellent agent
Implementation Method 3
supplying a water-repellent agent to the front surface of the substrate to impart water-repellency to the front surface of the substrate
Implementation Method 4
supplying a second solvent to the front surface of the substrate to which water-repellency is imparted and removing the second solvent from the front surface of the substrate
Implementation Method 5
a specific gravity of the second solvent is larger than the specific gravity of the water-repellent agent
Data Source
AI summary
Disclosed is a liquid processing method of drying a substrate held horizontally after supplying deionized water to the substrate. The liquid processing method includes: supplying the deionized water to a front surface of the substrate; supplying a first solvent to the front surface of the substrate after supplying the deionized water; supplying a water-repellent agent to the front surface of the substrate to impart water-repellency to the front surface of the substrate; supplying a second solvent to the front surface of the substrate to which water-repellency is imparted; and removing the second solvent from the front surface of the substrate. A specific gravity of the first solvent is smaller than a specific gravity of the water-repellent agent, and a specific gravity of the second solvent is larger than the specific gravity of the water-repellent agent.