Wafer Holder Adhesive Layer Design for Thermal Stress Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wafer holders with ceramic electrostatic chucks bonded to metal cooling plates face challenges in maintaining adhesion at high temperatures due to thermal expansion differences, leading to deformation or cracking, and existing solutions with flexible adhesive layers are prone to peeling issues.
Innovation Solution
A wafer holder design featuring a resin adhesive layer with a high-heat-resistant first layer in contact with the electrostatic chuck, a flexible second layer in contact with the cooling plate, and an intermediate layer with high heat resistance to prevent air entrapment and ensure hermetic contact, balancing heat resistance and stress relaxation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a flexible adhesive layer is used to absorb thermal expansion differences, then stress relaxation is improved, but peeling occurs between layers
Solution Approach 1:
The adhesive layer is divided into three distinct layers with different properties: a first layer in contact with the electrostatic chuck, a second layer in contact with the cooling plate, and an intermediate layer between them. This segmentation allows each layer to perform its specific function - the first and intermediate layers provide heat resistance while the second layer provides flexibility for stress relaxation, preventing peeling between layers.
Solution Approach 2:
Different regions of the adhesive layer are assigned different material properties to match local requirements. The first layer near the electrostatic chuck has high heat resistance to withstand temperatures from the chuck, the intermediate layer has high heat resistance and low flexibility to maintain structural integrity, and the second layer near the cooling plate has high flexibility to absorb thermal expansion differences and prevent peeling.
2Temperature
If a heat-resistant resin is used to withstand high temperatures, then heat resistance is improved, but deformation or cracking occurs due to high modulus of elasticity
Solution Approach 1:
The adhesive system is segmented into three layers where only the first and intermediate layers use heat-resistant resins with high modulus of elasticity. The second layer uses a flexible adhesive with low modulus of elasticity to compensate for the brittleness of heat-resistant materials, preventing deformation and cracking while maintaining heat resistance where needed.
Solution Approach 2:
The adhesive layer is constructed as a composite of three different materials: heat-resistant resin for the first and intermediate layers to withstand high temperatures, and flexible adhesive for the second layer to provide stress relaxation. This composite structure combines the advantages of heat resistance and flexibility, preventing both deformation at high temperatures and peeling between layers.
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 solution maintains a good adhesion state between the electrostatic chuck and cooling plate at high temperatures (up to 150°C or higher) by preventing peeling and deformation, ensuring reliable operation without air bubbles between layers.
Implementation Method 1
putting the laminate into a bag, decompressing the inside of the bag, and pressurizing and heating the bag from the outside
Implementation Method 2
difference in thermal expansion between the ceramics and the cooling plate cannot be absorbed
Implementation Method 3
the adhesive layer having the flexibility is disposed and, therefore, even in the case where a stress is generated at the time of heating, the resulting stress can be relaxed by the adhesive layer
Implementation Method 4
the resin is cured by heating to a curing temperature or higher while being pressed
Data Source
AI summary
A wafer holder 10 includes a resin adhesive layer 16 between a ceramic electrostatic chuck 12 and a metal cooling plate 14. The adhesive layer 16 includes a first layer 16a in contact with the electrostatic chuck 12, a second layer 16b in contact with the cooling plate 14, and an intermediate layer 16c located between the first layer 16a and the second layer 16b. Heat resistance of each of the first layer 16a and the intermediate layer 16c is higher than heat resistance of the second layer 16b, flexibility of the second layer 16b is higher than flexibility of each of the first layer 16a and the intermediate layer 16c, and the layers are in hermetic contact with each other.