Wafer Drying Using Supercritical Fluid Phase Transition
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Solution Overview
Problem
Conventional wafer drying methods cause collapse of crystal grain structures due to surface tension and require expensive equipment and high temperatures, leading to reduced semiconductor component quality and increased production costs.
Innovation Solution
A method utilizing supercritical fluids with no surface tension, which dissolves cleaning solvents at room temperature, preventing structural damage and simplifying the drying process by maintaining the wafer structure intact without heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional drying methods (spin dryer, solvent vaporization) are used, then the wafer can be dried, but the surface tension of the solvent causes collapse of the crystal grain structure
Solution Approach 1:
The patent changes the physical state of the drying fluid from liquid to supercritical fluid. By increasing pressure and temperature to reach supercritical conditions, the fluid's surface tension disappears completely, eliminating the harmful surface tension effect that causes crystal grain collapse during conventional drying
Solution Approach 2:
The patent utilizes the phase transition of the drying fluid to supercritical state. The fluid undergoes phase transition from liquid to supercritical fluid, which fundamentally changes its properties including the elimination of surface tension, allowing drying without structural damage
2Ease of manufacture
If conventional drying methods are used, then drying can be performed, but expensive equipment and high temperatures are required, increasing production cost
Solution Approach 1:
The patent optimizes the pressure and temperature parameters to reach supercritical conditions. By carefully selecting and controlling these parameters, the process achieves effective drying while avoiding excessive temperature requirements and reducing equipment complexity compared to conventional methods
3Productivity
If conventional drying methods are used, then drying can be performed, but the process is complex and time-consuming
Solution Approach 1:
The patent utilizes the unique properties of supercritical fluid phase transition. The direct transition to supercritical state and subsequent depressurization enables a simplified, single-step drying process that is both faster and less complex than multi-step conventional drying methods
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 improves wafer product yield, increases process efficiency, and reduces production costs by effectively drying wafers at room temperature without structural damage, using supercritical fluids like carbon tetrafluoride, which maintains the integrity of the semiconductor components.
Implementation Method 1
implanting a supercritical fluid into the reaction chamber, and increasing a pressure of the reaction chamber to dissolve the cleaning solvent in the supercritical fluid
Implementation Method 2
the surface tension of the solvent S pulls the transistors T on both sides and causes the structure collapse of the transistors T during the drying process
Data Source
AI summary
A method for drying a wafer at room temperature includes a cleaning step, a reacting step and a pressure releasing step. The cleaning step includes putting a processing workpiece into a cleaning solvent. The reacting step includes putting the processing workpiece along with the cleaning solvent into a reaction chamber, implanting a supercritical fluid into the reaction chamber, and increasing a pressure of the reaction chamber to dissolve the cleaning solvent in the supercritical fluid. A critical temperature of the supercritical fluid is below room temperature. The pressure releasing step includes releasing the pressure of the reaction chamber and discharging the supercritical fluid together with the cleaning solvent out of the reaction chamber, after completely dissolving the cleaning solvent in the supercritical fluid.