Supercritical Drying Apparatus for Substrate Pattern Collapse Prevention
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Solution Overview
Problem
The challenge in semiconductor manufacturing is the pattern collapse phenomenon during the drying process of substrates, where uneven drying of solutions leads to convex features falling due to lost surface tension, causing contamination and processing issues.
Innovation Solution
A substrate processing apparatus that uses a supercritical fluid to dry substrates by replacing the liquid with a supercritical-state fluid and then depressurizing it to a gaseous state, eliminating the surface tension effect, while a movable liquid bath is cooled externally to prevent evaporation and heated internally to maintain the supercritical state efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a substrate is carried into a transfer chamber and then transferred to a drying processing chamber using a substrate transferring robot, then the substrate can be dried by supercritical fluid, but the liquid on the substrate surface may evaporate before processing starts, causing pattern collapse
Solution Approach 1:
The substrate is immersed in a liquid bath immediately before supercritical drying, ensuring the surface is wetted in advance. This preliminary wetting prevents premature evaporation and pattern collapse during the transfer and heating phases, as the liquid provides a protective barrier until the supercritical fluid takes over the drying function
Solution Approach 2:
A liquid bath serves as an intermediary medium between the substrate and the supercritical drying environment. The liquid bath maintains the substrate in a wet state during transfer operations, acting as a buffer that prevents direct exposure to atmospheric conditions that would cause evaporation and pattern collapse
2Productivity
If the liquid bath is heated to change fluid to supercritical state, then drying efficiency improves, but evaporation of liquid in the bath occurs causing contaminant generation
Solution Approach 1:
The system is divided into separate functional zones: a liquid bath heating unit and a supercritical drying chamber. The liquid bath is heated independently to prepare the fluid, while the substrate processing occurs in a separate chamber where the fluid transitions to supercritical state. This segmentation prevents contaminant generation in the liquid bath from affecting the substrate
Solution Approach 2:
The heating function is extracted from the substrate processing chamber and placed in a separate liquid bath unit. By removing the heating source from the drying chamber, the patent eliminates the risk of liquid evaporation and contaminant generation during the heating phase, while still achieving supercritical drying through controlled fluid transfer
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 suppresses pattern collapse and contaminant generation by ensuring uniform drying without surface tension influence, enhancing operational freedom and responsiveness in the processing sequence.
Implementation Method 1
a processing vessel configured to dispose the liquid bath in an internal processing space, replace the liquid in the liquid bath with a supercritical-state fluid, and depressurize the processing space such that the supercritical-state fluid is changed to a gaseous state
Implementation Method 2
there is no interface between a liquid and a gas at an equilibrium state of the supercritical fluid. Therefore, the liquid attached to the wafer is replaced with the supercritical fluid, and thereafter, when the supercritical fluid is changed to a gaseous state, the liquid may be dried without being influenced by the surface tension
Implementation Method 3
a heating mechanism configured to heat the processing space in order to change the fluid supplied to the processing vessel to the supercritical state or maintain the supercritical state
Implementation Method 4
a cooling mechanism configured to cool down the liquid bath moved to the stand-by location
Data Source
AI summary
Disclosed is a substrate processing apparatus capable of drying a substrate to be processed while suppressing the pattern collapse or the occurrence of contamination. A substrate is held in a liquid bath while being immersed in a liquid, and the liquid bath is disposed in a processing space of a processing vessel. A processing of drying the substrate is performed by replacing the liquid in the liquid bath with a supercritical-state fluid. A predetermined mechanism moves liquid bath between a processing location in the processing case and a stand-by location outside the processing case. A heater installed in the processing case changes the fluid to a supercritical state or maintains the supercritical state while cooling mechanisms cool down the liquid bath moved to the stand-by location outside the processing vessel.