Supercritical Fluid Drying for Semiconductor Pattern Integrity
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Solution Overview
Problem
The wet processes in semiconductor manufacturing, such as wet cleaning and wet etching, often result in fine patterns on substrates collapsing or forming bridge defects during the drying process due to reduced design rules, which existing technologies fail to effectively address.
Innovation Solution
An apparatus and method utilizing supercritical fluids to treat substrates, involving a process chamber, a supply module for introducing supercritical fluids, a pressure drop module for gradually reducing pressure, and a flow controller to alternate between pressure drop and supplemental modes, ensuring efficient chemical removal and preventing pattern damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional drying processes are used for wet cleaning and etching, then the drying function is achieved, but fine patterns on substrates collapse or form bridge defects
Solution Approach 1:
The patent changes the physical parameters of the drying process by using supercritical fluid instead of conventional gas drying. The supercritical fluid is maintained at specific pressure and temperature parameters (above critical point) to achieve effective chemical removal while preventing pattern collapse, thus resolving the contradiction between reliable drying and pattern shape accuracy
Solution Approach 2:
The patent utilizes phase transition of the fluid from supercritical state to liquid/gas state for effective chemical removal. By controlling the phase transition of supercritical CO2, the system achieves thorough chemical penetration and removal without causing the mechanical stress that leads to pattern collapse in conventional drying
2Productivity
If design rules are reduced to increase device density, then device integration is improved, but patterns become more susceptible to collapse and bridge defects during drying
Solution Approach 1:
By changing to supercritical fluid parameters, the patent achieves effective cleaning of finer patterns without the mechanical stress of conventional drying, enabling higher device integration while maintaining pattern stability
Solution Approach 2:
The supercritical fluid acts as an intermediary medium that can penetrate fine patterns more effectively than conventional gases, removing chemicals thoroughly while providing mechanical support during the drying process, thus preventing collapse in high-density devices
3Productivity
If pressure is rapidly dropped to remove chemicals, then chemical removal speed is improved, but ice particles form and may damage substrates
Solution Approach 1:
The patent uses periodic alternation between pressure drop mode and supplemental mode to control the pressure reduction process. This periodic action allows controlled chemical removal while preventing rapid pressure changes that would cause ice particle formation
Solution Approach 2:
The supplemental mode performs preliminary action by maintaining pressure and supplying supercritical fluid before complete pressure drop, ensuring thorough chemical removal and preventing conditions that lead to ice particle formation during the subsequent pressure reduction
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 effectively prevents pattern collapse and bridge defects by using supercritical fluids to alternately repeat pressure drop and supplemental modes, enhancing chemical removal efficiency and minimizing ice particle formation during the drying process.
Implementation Method 1
a supply module to supply the supercritical fluid into the process chamber
Implementation Method 2
a turbulent flow generator to turbulently supplement the supercritical fluid into the process chamber
Implementation Method 3
a pressure drop module to drop the inner pressure of the process chamber to a second pressure below the first pressure by partially removing a supercritical mixture
Implementation Method 4
a flow controller alternately repeating a pressure drop mode and a supplemental mode, the supercritical mixture partially flowing out from the process chamber when the inner pressure reaches the first pressure
Data Source
AI summary
A method of processing substrates, comprising: loading a substrate into a process chamber; supplying a supercritical fluid, that is a process fluid under the supercritical state, into the process chamber, chemicals separated from the substrate and the supercritical fluid being mixed into a supercritical mixture in the process chamber; and gradually decreasing a chemical concentration of the supercritical mixture by alternately repeating a pressure drop mode and a supplemental mode such that the supercritical mixture partially flows out from the process chamber at the pressure drop mode when an inner pressure of the process chamber reaches a first pressure and the supercritical fluid turbulently flows into the process chamber at the supplemental mode when the inner pressure of the process chamber reaches a second pressure that is smaller than the first pressure and over a supercritical pressure of the process fluid.