Semiconductor Drying via Filtered IPA Vapor
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Solution Overview
Problem
Conventional spin drying methods for semiconductor substrates fail to completely remove moisture between capacitors, leading to capacitor leaning and malfunction due to residual impurities in IPA vapor and decreased cohesive force between IPA and nitrogen gas.
Innovation Solution
A method involving preheating nitrogen gas and isopropyl alcohol (IPA) to form a gas mixture, which is then second-heated and filtered to remove impurities before application to the substrate, ensuring sufficient IPA vapor is applied to dry the substrate effectively and prevent capacitor leaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the gas mixture is heated to prevent condensation, then the gas mixture temperature increases, but impurities remain in the heated gas mixture causing decreased cohesive force
Solution Approach 1:
The patent applies preliminary filtering before the gas mixture is heated. The gas mixture is first filtered to remove impurities, then heated to prevent condensation. This sequence ensures that the heating process does not concentrate impurities that would otherwise decrease the cohesive force between IPA vapor and nitrogen gas during drying.
Solution Approach 2:
The patent extracts impurities from the gas mixture by passing it through a filter before heating. This removal of harmful impurities prevents the decrease in cohesive force that would occur if impurities remained in the heated gas mixture, thereby maintaining reliable drying performance.
2Reliability
If IPA vapor is supplied to the drying chamber, then the drying effect improves, but IPA vapor partially condenses decreasing the amount applied to capacitors
Solution Approach 1:
The patent applies preliminary heating to the gas mixture before it enters the drying chamber. By heating the gas mixture in advance, the IPA vapor maintains its gaseous state during transport, preventing partial condensation and ensuring sufficient quantity of IPA vapor reaches the capacitors for effective drying.
Solution Approach 2:
The patent changes the temperature parameter of the gas mixture by heating it before supply to the drying chamber. This parameter change prevents condensation of IPA vapor during transport, maintaining both the drying effect and sufficient quantity of IPA vapor applied to the capacitors.
3Ease of manufacture
If spin drying is used to remove moisture, then the drying process is simple, but droplets of deionized water remain on the semiconductor substrate
Solution Approach 1:
The patent replaces the mechanical spin drying system with a chemical vapor drying system using heated and filtered IPA vapor. This substitution eliminates the vortexes and incomplete drying problems of spin drying while maintaining process simplicity, achieving complete moisture removal between capacitors.
4Productivity
If rapid rotation is used during spin drying, then the drying speed increases, but vortexes are generated that contaminate the semiconductor substrate
Solution Approach 1:
The patent replaces the rapid rotation mechanical drying system with a stationary vapor drying system. By using heated IPA vapor that flows over the substrate, the method achieves effective drying without generating vortexes that would contaminate the semiconductor substrate, thereby eliminating the harmful effects while maintaining 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
The method ensures complete removal of deionized water between capacitors, preventing leaning and ensuring the capacitors maintain their intended height and functionality.
Implementation Method 1
first heating a first fluid and a second fluid to form a gas mixture
Implementation Method 2
second heating the first heated gas mixture, filtering the second heated gas mixture to filter impurities from the second heated gas mixture
Implementation Method 3
filtering the second heated gas mixture to filter impurities from the second heated gas mixture
Implementation Method 4
applying the filtered gas mixture to the object to dry the object
Implementation Method 5
This method utilizes the Marangoni Effect, for example, and relies on the low surface tension of IPA vapors
Data Source
AI summary
In a method of drying an object, a first drying fluid and a second dry fluid may be first heated to form a gas mixture. The gas mixture may be second heated to prevent the mixed gas from condensing. The second heated gas mixture may be filtered to remove impurities from the second heated mixed gas. The filtered mixed gas may be then applied to the object so as to dry the object.