Wafer Cooling Plate Layout for Uniform Refrigerant Temperature
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Solution Overview
Problem
The existing wafer placement apparatuses suffer from low temperature uniformity due to a significant temperature gradient in the refrigerant passage, leading to uneven cooling of wafers, particularly when the refrigerant passage is long, resulting in higher temperatures near the outlet.
Innovation Solution
The apparatus features a ceramic plate with a cooling plate having separate refrigerant passages, where one passage is shorter and paired with an inversely positioned second passage, both with swirling shapes, to reduce temperature gradients and enhance uniformity by offsetting temperature differences across the cooling plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single long refrigerant passage is used, then the cooling plate can cover the entire wafer placement surface, but the temperature uniformity deteriorates due to large temperature gradient along the passage
Solution Approach 1:
The single long refrigerant passage is divided into multiple separate passages (first passage and second passage). Each passage has a shorter length, which reduces the temperature gradient along the flow path. The passages are arranged to collectively cover the entire cooling plate area, maintaining full coverage while improving temperature uniformity.
Solution Approach 2:
The first and second passages are positioned with inverted flow directions - the inlet of one passage is near the outlet of the other, and vice versa. This inversion causes the temperature gradients of the two passages to offset each other, reducing the overall temperature difference across the cooling plate.
2Area of stationary object
If the refrigerant passage length is increased to cover more area, then the cooling coverage is improved, but the refrigerant temperature increases due to extended heat exchange distance
Solution Approach 1:
The long refrigerant passage is segmented into multiple shorter passages. Each shorter passage limits the maximum heat exchange distance, preventing the refrigerant from accumulating excessive temperature rise. The collective arrangement of these short passages achieves the required cooling coverage area.
3Device complexity
If a single refrigerant passage is used, then the device structure is simple, but the temperature difference between inlet and outlet becomes large
Solution Approach 1:
The single refrigerant passage is divided into multiple separate passages with inverted positioning. This segmentation increases the number of components but significantly reduces the temperature difference between inlet and outlet by limiting passage length and creating offsetting temperature gradients.
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 reduces the temperature difference across the cooling plate, resulting in improved temperature uniformity of the wafers by maintaining lower refrigerant temperatures around the outlets and minimizing local steep gradients, thus enhancing the overall cooling performance.
Implementation Method 1
a ceramic plate having an upper surface as a wafer placement surface and in which an electrode is embedded; and a cooling plate provided on a lower surface, opposite the wafer placement surface, of the ceramic plate and in which a refrigerant passage is provided
Implementation Method 2
While the refrigerant supplied into the refrigerant passage is flowing through the refrigerant passage, the refrigerant continues to be heated by exchanging heat with the ceramic plate
Data Source
AI summary
A wafer placement apparatus includes a ceramic plate having an upper surface as a wafer placement surface and in which an electrode is embedded; and a cooling plate provided on a lower surface, opposite a wafer placement surface, of a ceramic plate and in which a refrigerant passage is provided, wherein a refrigerant passage includes a first passage forming a single continuous line and extending parallel to a wafer placement surface, and a second passage forming a single continuous line and extending along a first passage, an outlet of a second passage being positioned near an inlet of a first passage, an inlet of a second passage being positioned near an outlet of a first passage.