Substrate Cleaning via Leidenfrost Steam Layer
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Solution Overview
Problem
In semiconductor device manufacturing, the removal of cleaning fluids from substrates with complex patterns leads to pattern collapse due to surface tension, and existing methods either fail to adequately address this issue or result in contamination or require high-pressure equipment.
Innovation Solution
The method involves heating the substrate to induce the Leidenfrost phenomenon, where steam from the cleaning fluid interposes between the substrate and droplets, reducing surface tension contact and preventing pattern collapse, using a cleaning fluid with a boiling point lower than the substrate temperature, and supplying the fluid in a mist form while rotating the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If cleaning fluid is supplied onto the substrate surface to remove residues, then cleaning effectiveness is improved, but pattern collapse occurs due to surface tension forces
Solution Approach 1:
The substrate is heated to a temperature above the boiling point of the cleaning fluid, causing the cleaning fluid to undergo phase transition from liquid to vapor upon contact with the substrate. This phase transition creates steam bubbles that interpose between the liquid cleaning fluid and the substrate surface, reducing direct liquid contact and minimizing surface tension forces that cause pattern collapse while maintaining cleaning effectiveness through the phase change process
Solution Approach 2:
Steam bubbles act as an intermediary layer between the cleaning fluid and the substrate surface. This intermediate vapor phase reduces the direct contact between the liquid cleaning fluid and the patterned substrate, thereby minimizing the harmful surface tension forces while still allowing the cleaning process to occur effectively
2Stability of the object's composition
If substrate temperature is increased to reduce cleaning fluid surface tension, then pattern collapse is prevented, but cleaning fluid evaporation becomes too rapid
Solution Approach 1:
The substrate temperature is controlled to be above the boiling point of the cleaning fluid, inducing phase transition from liquid to vapor. This controlled phase change manages the evaporation process, creating steam bubbles that provide mechanical cleaning action while the vaporization process itself removes the cleaning fluid, thus preventing both pattern collapse and excessive liquid contact time
3Manufacturing precision
If cleaning fluid is supplied in liquid form, then cleaning effectiveness is improved, but high-pressure equipment is required to prevent pattern collapse
Solution Approach 1:
The cleaning process utilizes phase transition from liquid to vapor through thermal energy rather than mechanical pressure. By heating the substrate above the boiling point of the cleaning fluid, the liquid cleaning fluid vaporizes upon contact, creating steam bubbles that provide the necessary cleaning action without requiring high-pressure equipment, thus simplifying the device complexity while maintaining cleaning effectiveness
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 removes residues without collapsing patterns, reduces contamination risks, and does not require high-pressure equipment, ensuring efficient cleaning while maintaining pattern integrity.
Implementation Method 1
heating the substrate so that the Leidenfrost phenomenon occurs and steam of the cleaning fluid is interposed between the substrate and droplets of the cleaning fluid supplied to the substrate
Implementation Method 2
steam of the cleaning fluid is interposed between the substrate and droplets of the cleaning fluid supplied to the substrate
Data Source
AI summary
In a cleaning method, a substrate having a pattern formed on the surface thereof can be cleaned by using a cleaning fluid, while preventing the pattern protrusions from being flattened when the cleaning fluid is removed or dried. The cleaning method includes the steps of: loading a substrate onto a loading platform inside a processing chamber; heating the substrate; and supplying a cleaning fluid onto the surface of the substrate. The substrate is heated in the substrate heating step so that the Leidenfrost phenomenon occurs and steam of the cleaning fluid is interposed between the substrate and droplets of the cleaning fluid supplied to the substrate in the cleaning fluid supply step.