Supercritical Fluid Supply Control for Wafer Drying Without Pattern Collapse
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Solution Overview
Problem
Existing substrate processing methods for semiconductor wafers face challenges in efficiently removing liquids from the wafer surface using supercritical fluid drying, which can lead to pattern collapse during the drying process.
Innovation Solution
A substrate processing apparatus is designed with a processing vessel and a processing fluid supply system that includes a cooling device, pump, heating device, flow rate adjusters, and a controller to manage the supply of processing fluid in a supercritical state, ensuring controlled drying and minimizing pattern collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a drying method using supercritical fluid is used to remove liquid from the wafer surface, then drying efficiency is improved, but pattern collapse may occur during the drying process
Solution Approach 1:
The patent applies preliminary action by pre-cooling the supercritical fluid in the fluid supply line before it enters the processing chamber. This cooling step prepares the fluid to transition from supercritical state to liquid state in a controlled manner, preventing sudden phase changes that could cause pattern collapse while maintaining efficient drying performance
Solution Approach 2:
The patent utilizes parameter changes by controlling the temperature and pressure of the processing fluid through the cooling device and heating device. By adjusting these parameters, the fluid transitions between supercritical, liquid, and gas states at appropriate times during the drying process, achieving both high drying efficiency and pattern protection
2Device complexity
If the processing fluid is supplied directly from gas state to supercritical state without cooling, then the process is simplified, but control precision over the drying process deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the fluid supply process into distinct stages: cooling section, pumping section, and heating section. Each section performs a specific function (cooling, pressurizing, heating) allowing independent control and optimization of each step, thereby achieving precise drying control without excessive overall complexity
Solution Approach 2:
The cooling device acts as an intermediary component between the gas state fluid source and the supercritical fluid delivery system. This intermediary step enables controlled transition through liquid state, providing better control precision over the phase change process while maintaining reasonable system complexity
3Productivity
If the flow rate of processing fluid is increased to improve drying speed, then productivity increases, but the risk of pattern collapse increases
Solution Approach 1:
The patent applies periodic action by controlling the flow rate of processing fluid in stages rather than continuously at high rate. The system first supplies fluid at controlled rates during critical phases, then increases flow rate when safe, achieving high overall drying speed while minimizing pattern collapse risk through timed flow rate variations
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 apparatus effectively suppresses pattern collapse by diffusing the supercritical fluid between patterns during the drying process, while also ensuring efficient pressure control and flow rate management, thereby enhancing the reliability of the substrate processing.
Implementation Method 1
a cooling device provided in the fluid supply line, and configured to cool the processing fluid in a gas state to produce the processing fluid in a liquid state
Implementation Method 2
a heating device provided in the fluid supply line to be positioned downstream of the pump, and configured to heat the processing fluid in the liquid state to generate the processing fluid in the supercritical state
Implementation Method 3
The apparatus effectively suppresses pattern collapse by diffusing the supercritical fluid between patterns during the drying process
Data Source
AI summary
A substrate processing apparatus includes a processing vessel; and a processing fluid supply configured to supply a processing fluid in a supercritical state into the processing vessel. The processing fluid supply includes a fluid supply line; a cooling device provided in the fluid supply line, and configured to cool the processing fluid in a gas state to produce the processing fluid in a liquid state; a pump positioned downstream of the cooling device; a heating device positioned downstream of the pump, and configured to heat the processing fluid in the liquid state to generate the processing fluid in the supercritical state; a first flow rate adjuster positioned between the pump and the heating device, and configured to adjust a supply flow rate of the processing fluid supplied to the processing vessel; and a controller configured to control the first flow rate adjuster.