Substrate Drying via Segmented Liquid Films
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Solution Overview
Problem
Conventional substrate drying methods can cause pattern collapse when the pattern height exceeds the thickness of the vapor layer formed on the substrate, as the organic solvent's surface tension acts on the pattern, leading to structural instability during drying.
Innovation Solution
A substrate processing method involving the formation of a second liquid film with higher vapor pressure and a first liquid film surrounding it, where the second liquid film is heated to create a thick vapor layer, allowing the film to float and expand without contacting the pattern, thereby preventing collapse by maintaining a gas-liquid interface above the pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single organic solvent liquid film is formed on the substrate and dried by heating, then the substrate can be dried efficiently, but pattern collapse occurs when pattern height exceeds vapor layer thickness due to surface tension acting on the pattern
Solution Approach 1:
The liquid film is segmented into two distinct layers: a first liquid film (water-based) and a second liquid film (organic solvent). The first liquid film forms the base layer that contacts the substrate, while the second liquid film floats on top. This segmentation allows the organic solvent to be positioned above the pattern structures, preventing surface tension from acting directly on the patterns during drying, thus avoiding pattern collapse while maintaining drying efficiency.
Solution Approach 2:
The first liquid film acts as an intermediary layer between the substrate and the second liquid film. It supports the second liquid film and transfers heat to it, enabling the organic solvent to evaporate and form a protective vapor layer above the pattern without the organic solvent directly contacting the pattern. This intermediary structure resolves the contradiction by decoupling the drying function from the pattern-contact function.
2Manufacturing precision
If the vapor layer thickness is increased to prevent pattern collapse, then pattern integrity is maintained, but the drying time and energy consumption increase
Solution Approach 1:
The invention changes the physical parameters of the liquid film system by using two liquids with different vapor pressures. The second liquid (organic solvent) has a higher vapor pressure than the first liquid (water), allowing it to evaporate more rapidly and form a sufficient vapor layer thickness quickly. This parameter change enables maintaining pattern integrity without excessively increasing drying time or energy consumption.
3Device complexity
If only a single liquid film is used, then the process is simple and fast, but it cannot prevent pattern collapse when pattern height is large
Solution Approach 1:
The invention applies local quality by giving different functions to different parts of the liquid film system. The first liquid film (water-based) provides thermal conduction and structural support, while the second liquid film (organic solvent) provides the vapor barrier function. This local differentiation of functions allows the system to prevent pattern collapse in specific areas (where patterns are present) without complicating the overall process structure.
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 effectively prevents pattern collapse during drying by maintaining a gas-liquid interface above the pattern, ensuring the substrate is dried without structural damage, even when the pattern height is greater than the vapor layer thickness.
Implementation Method 1
evaporating at least the second liquid in contact with the upper surface of the substrate by heating the substrate, forming a second vapor layer including vapor of the second liquid between the second liquid and the upper surface of the substrate
Implementation Method 2
removing the first liquid and the second liquid outside the substrate by moving the second liquid film on the second vapor layer
Data Source
AI summary
In a second liquid supply step, a second liquid film and a first liquid film surrounding a side of the second liquid film are formed on an upper surface of a substrate. Then, in a vapor layer formation step, by heating the substrate, a second vapor layer is formed by evaporating the second liquid contacting the upper surface of the substrate, and the second liquid film is held on the second vapor layer. Since the second liquid included in the second liquid film has a high vapor pressure, a height position of a lower surface of the floating second liquid film may be kept high. By blowing a gas to the floating second liquid film, a hole is formed in the second liquid film, and by expanding the hole toward an outer periphery of the substrate, the first liquid and the second liquid are removed outside the substrate.