Wafer Placement Table Cooling Structure for Low Thermal Stress
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Solution Overview
Problem
Existing wafer placement tables face increased manufacturing costs due to the use of expensive metal matrix composite materials or low thermal expansion metals for high heat dissipation and thermal stress management, which also complicates the formation of refrigerant flow channels.
Innovation Solution
A wafer placement table design incorporating a ceramic base with a metal bonding layer, a cooling base featuring a metal matrix composite or low thermal expansion metal ceiling, and a grooved or perforated base made from the same ceramic material, utilizing near-net-shape manufacturing to reduce costs while maintaining high thermal conductivity and minimizing thermal expansion differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal matrix composite material or low thermal expansion metal material is used for the cooling base, then heat dissipation performance is improved and thermal stress is reduced, but manufacturing cost increases and difficulty of forming refrigerant flow channels increases
Solution Approach 1:
The cooling base is divided into two separate bases: a first cooling base made of inexpensive ceramic material and a second cooling base made of metal matrix composite or low thermal expansion metal material. This segmentation allows the expensive material to be used only where thermal stress management is critical, while the majority of the structure uses cost-effective ceramic material.
Solution Approach 2:
The patent applies different material qualities to different regions of the cooling base. The second cooling base (made of metal matrix composite or low thermal expansion metal) is positioned at the location where thermal stress occurs during wafer processing, providing localized high-performance material properties where needed, while the first cooling base uses standard ceramic material elsewhere.
2Reliability
If a metal bonding layer is used instead of a resin layer, then heat dissipation performance is improved, but the influence of thermal expansion difference between ceramic base and cooling base increases
Solution Approach 1:
The cooling base is segmented into two parts with different material properties. The first cooling base (ceramic) has thermal expansion properties similar to the support base, while the second cooling base (metal matrix composite or low thermal expansion metal) provides high heat dissipation. This segmentation allows the system to achieve both low thermal stress and high heat dissipation performance.
Solution Approach 2:
The patent uses a composite structure combining ceramic material (first cooling base) with metal matrix composite or low thermal expansion metal material (second cooling base). This composite approach allows the system to simultaneously exhibit the thermal expansion compatibility of ceramics and the high thermal conductivity of metals, resolving the contradiction between heat dissipation and thermal stress.
3Object-affected harmful factors
If a resin layer is used to bond the ceramic base and cooling base, then the influence of thermal expansion difference is reduced, but heat dissipation performance decreases
Solution Approach 1:
The cooling base is divided into two segments with different material properties. The first segment (ceramic) matches the thermal expansion of the support base, eliminating the need for stress-absorbing resin layers. The second segment (metal matrix composite or low thermal expansion metal) provides high heat dissipation performance, eliminating the need for low-conductivity resin layers.
Solution Approach 2:
The patent employs a composite cooling base structure that combines ceramic material with metal matrix composite or low thermal expansion metal material. This composite design allows the system to achieve both thermal expansion compatibility (reducing stress) and high thermal conductivity (improving heat dissipation) without relying on resin layers that compromise either property.
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 manufacturing costs, enhances heat dissipation performance, and minimizes the risk of thermal stress-related issues like warpage or breakage, while allowing for efficient production and flexible material usage.
Implementation Method 1
Since a metal bonding layer is higher in thermal conductivity than a resin layer, it is possible to achieve heat dissipation performance required in the case where a wafer is processed with high-power plasma
Implementation Method 2
a cooling base in which a refrigerant flow channel is formed
Implementation Method 3
a ceramic base made of alumina or the like in which an electrostatic attraction electrode is embedded
Data Source
AI summary
A wafer placement table includes a ceramic base having a wafer placement surface on its top surface and incorporating an electrode, a cooling base in which a refrigerant flow channel is formed, and a metal bonding layer that bonds the ceramic base with the cooling base. The cooling base includes a ceiling base made of a metal matrix composite material or a low thermal expansion metal material and defining a ceiling of the refrigerant flow channel, a grooved base of which a main component is made of the same ceramic material as a main component of the ceramic base and on a top surface of which a flow channel groove defining a bottom and a side wall of the refrigerant flow channel is provided, and a metal ceiling bonding layer that bonds a bottom surface of the ceiling base with the top surface of the grooved base.