Supercritical Substrate Drying with Bottom-Side Fluid Supply
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Solution Overview
Problem
Conventional substrate processing methods using supercritical fluids often result in defects due to high pressure and flow rate when the fluid is supplied, especially when supplied through the upper side of the chamber, leading to pattern collapse and damage during the drying process of semiconductor wafers.
Innovation Solution
A substrate processing method that includes a pressurization operation where the fluid is supplied through the lower side of the chamber, a process operation where the fluid is simultaneously supplied and discharged, and a depressurization operation, with the fluid being supplied through the lower side during at least some sections of the process operation to reduce defects, and optionally alternating between supplying through the lower and upper sides or generating a pulse wave.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If supercritical fluid is supplied through the upper side of the chamber in equal pressure operation, then the drying process can be performed, but defects occur due to high pressure and flow rate causing pattern collapse
Solution Approach 1:
The patent inverts the conventional supply direction by supplying supercritical fluid through the lower side of the chamber instead of the upper side. This reversal prevents the high-pressure fluid from directly impacting patterns from above, thereby avoiding pattern collapse while maintaining drying efficiency
Solution Approach 2:
The patent implements periodic action by alternating between pressurization operation (supplying fluid through lower side), equal pressure operation (supplying through upper side), and depressurization operation. This periodic cycle allows the system to maintain drying efficiency while minimizing pattern damage through controlled pressure variations
2Productivity
If supercritical fluid is supplied at high flow rate to maintain processing speed, then productivity is improved, but pattern collapse increases due to capillary force
Solution Approach 1:
The patent changes the parameter of fluid supply direction from upper side to lower side during pressurization operation. This parameter change allows high flow rate to be maintained for productivity while the downward flow direction prevents capillary force from acting upward on patterns, thus avoiding pattern collapse
3Device complexity
If conventional drying method using temperature control is used, then the process is simple, but capillary force is generated at gas-liquid interface causing pattern collapse
Solution Approach 1:
The patent utilizes phase transitions of the supercritical fluid by cycling through pressurization (liquid to supercritical), equal pressure (supercritical state maintenance), and depressurization (supercritical to gas) operations. This phase transition approach eliminates the gas-liquid interface that causes capillary force, thereby preventing pattern collapse while maintaining process control
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 significantly reduces defects on the substrate by controlling the fluid flow and pressure, minimizing pattern collapse and enhancing drying efficiency without capillary force issues, as evident from reduced defect patterns compared to conventional methods.
Implementation Method 1
a treatment method of drying the treatment liquid by using a fluid in a supercritical state (hereinafter referred to as 'supercritical fluid')
Implementation Method 2
When a supercritical fluid is used, if the supercritical fluid is supplied into the chamber, defects to the substrate may occur due to the high pressure and flow rate of the supercritical fluid at the beginning of supply
Implementation Method 3
The capillary force causing the pattern collapse described above is caused by an atmospheric atmosphere surrounding the substrate S after cleaning and a surface tension of the treatment liquid functioning at a liquid/gas interface with the treatment liquid remaining between patterns
Implementation Method 4
When a supercritical fluid is used, if the supercritical fluid is supplied into the chamber, defects to the substrate may occur due to the high pressure and flow rate of the supercritical fluid at the beginning of supply
Implementation Method 5
when a fluid is dried through a supercritical state by using both temperature and pressure control of the fluid, a gas-liquid equilibrium line is not passed, and thus it is possible to dry a substrate in a state essentially free of capillary force
Data Source
AI summary
The present disclosure relates to a substrate processing method, and more particularly, to a substrate processing method of a substrate processing device using a supercritical fluid, to reduce damage or defects to a substrate when the supercritical fluid is supplied into the chamber.