Electrostatic Chuck Evaporative Cooling via Capillary Wicking
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Solution Overview
Problem
Existing substrate processing systems face challenges in efficiently cooling electrostatic chucks due to limited cooling capacity and temperature range of conventional methods, which often rely on high-pressure gases or toxic liquids, and struggle with two-phase flow control in evaporative cooling systems.
Innovation Solution
The implementation of an evaporative cooling system with a specially designed evaporator using cryogenic liquids and a wicking material-coated cavity within the electrostatic chuck, allowing for controlled evaporation and efficient heat transfer, addressing issues of heat transfer uniformity and two-phase flow stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional cooling methods (high-pressure gases or toxic liquids) are used, then cooling capacity is limited, but system complexity and safety risks increase
Solution Approach 1:
The patent employs evaporative cooling where a liquid coolant undergoes phase transition from liquid to vapor within the electrostatic chuck cavity. The liquid is supplied through capillary wicking material, evaporates to absorb heat from the substrate and chuck, and the vapor is then condensed and returned to complete the cycle. This phase change mechanism provides high cooling capacity without requiring complex high-pressure gas systems or toxic liquids.
2Power
If evaporative cooling is implemented, then cooling efficiency improves, but two-phase flow control becomes difficult
Solution Approach 1:
The patent utilizes capillary wicking material with controlled porosity to manage the two-phase flow. The porous structure of the wicking material automatically distributes the liquid coolant uniformly across the evaporation surface and controls the evaporation rate through capillary action. This eliminates the need for complex external control systems for two-phase flow, as the porous material inherently regulates the liquid-vapor transition and flow patterns.
Solution Approach 2:
The evaporative cooling system is designed to be self-regulating through the capillary wicking mechanism. The porous wicking material automatically adjusts liquid supply to the evaporation zone based on local temperature and vapor pressure conditions, without requiring external control systems. The system self-manages the two-phase flow distribution and evaporation rate, simplifying operation while maintaining high cooling efficiency.
3Temperature
If high cooling capacity is achieved, then temperature range expands, but heat transfer uniformity becomes challenging
Solution Approach 1:
The patent implements local quality optimization by distributing the liquid coolant supply through multiple capillary wicking structures positioned at different locations within the electrostatic chuck cavity. Each wicking region provides localized evaporation and heat transfer, ensuring uniform temperature distribution across the substrate surface. This distributed approach maintains heat transfer uniformity even when achieving expanded temperature ranges through high cooling capacity.
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 solution provides efficient and repeatable cooling with high cooling capacity at cryogenic temperatures, overcoming limitations of conventional methods by ensuring stable evaporation and effective heat transfer, thus enhancing the cooling performance of substrate processing systems.
Implementation Method 1
an evaporative cooling system with a specially designed evaporator using cryogenic liquids and a wicking material-coated cavity within the electrostatic chuck, allowing for controlled evaporation and efficient heat transfer
Implementation Method 2
the pillars are coated with a wicking material
Implementation Method 3
allowing for controlled evaporation and efficient heat transfer, addressing issues of heat transfer uniformity and two-phase flow stability
Implementation Method 4
efficient heat transfer, addressing issues of heat transfer uniformity and two-phase flow stability
Data Source
AI summary
A baseplate of a substrate support assembly includes a cavity between an upper region, a lower region, and sidewalls of the baseplate, a plurality of pillars arranged in the cavity between the upper and lower regions, an inlet to supply a liquid to the cavity, and an outlet to vent vapor of the liquid. In another implementation, a baseplate of a substrate support assembly includes a first channel arranged in the baseplate, a second channel arranged above the first channel, a plurality of vertical channels connecting the first channel to the second channel, an inlet to supply a liquid to the first channel, and an outlet to vent vapor of the liquid from the second channel.