Rotating Wafer Cooling Stage Using Gas-Mediated Heat Transfer
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Solution Overview
Problem
Existing sputtering apparatuses face difficulties in efficiently cooling wafers while rotating them due to thermal resistance and the complexity of integrating high refrigeration capabilities with wafer stage rotation, leading to inadequate cooling efficiency.
Innovation Solution
A cooling system for sputtering apparatuses that includes a wafer cooling stage, a cooling mechanism, cooling gas supply units, a wafer rotating mechanism, and a driving mechanism, allowing the wafer to be rotated adjacent to a low-temperature cooling stage with a predetermined gap, enabling simultaneous rotation and cooling of the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a refrigerator is directly connected to a wafer stage to achieve low-temperature control, then the wafer stage can be cooled to very low temperatures (100K or less), but it becomes very difficult to rotate the wafer stage due to the weight and complexity of the refrigerator system
Solution Approach 1:
The system is divided into three independent parts: the stationary refrigerator, the rotatable wafer stage, and the cooling gas supply mechanism. The refrigerator remains fixed while only the wafer stage and gas supply rotate, eliminating the problem of rotating heavy refrigerator components.
Solution Approach 2:
Cooling gas (such as helium) serves as an intermediary to transfer thermal energy from the refrigerator to the wafer. The gas is cooled by the stationary refrigerator, then supplied to the rotating wafer stage through a rotating seal, enabling cooling without mechanically connecting the refrigerator to the rotating stage.
2Ease of operation
If a wafer holder is positioned between the cooling mechanism and substrate to allow rotation, then the wafer can be rotated, but the substrate cannot be cooled efficiently due to thermal resistance
Solution Approach 1:
The system uses a gas-based cooling mechanism where cooled gas is supplied directly to the wafer surface through nozzles on the rotating wafer stage. This pneumatic cooling method eliminates thermal resistance issues associated with solid-to-solid heat transfer through a thick wafer holder, enabling efficient cooling while maintaining rotation capability.
3Temperature
If cooling water is circulated through a cooler that rotates with the wafer stage, then the wafer can be cooled during rotation, but the system becomes complex and the cooling efficiency is insufficient for very low temperatures
Solution Approach 1:
The patent replaces the mechanical water circulation system with a gas-based cooling system. Instead of pumping liquid water through rotating channels, the system uses a stationary refrigerator to cool gas, then supplies the cold gas to the rotating wafer stage through a rotating seal. This substitution eliminates complex rotating mechanical components while achieving superior cooling performance.
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 configuration allows for efficient cooling of the wafer to low temperatures while maintaining its rotation, improving the overall cooling efficiency and addressing the limitations of previous systems.
Implementation Method 1
cooling gas supply units which introduces a cooling gas to the wafer cooling stage
Implementation Method 2
a cooling mechanism which cools the wafer cooling stage
Data Source
AI summary
A cooling system that cools a wafer in a vacuum chamber of a sputtering apparatus, includes a wafer cooling stage for cooling the wafer, a cooling mechanism for cooling the wafer cooling stage, cooling gas supply units which introduces a cooling gas to the wafer cooling stage, a wafer rotating mechanism which holds the wafer in a state separated from the wafer cooling stage by a predetermined gap, and is rotated while holding the wafer, and a driving mechanism which rotates the wafer rotating mechanism at a predetermined rotational speed.