Electrostatic Chuck Adhesive Layer Thermal Conductivity
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Solution Overview
Problem
Conventional electrostatic chucks face challenges with uneven thermal conductivity and voids in the adhesive layer, leading to temperature distribution variations and reliability issues due to high viscosity adhesives with high filler content, which affect the bonding of heaters to base plates and increase the risk of peeling.
Innovation Solution
A two-layered adhesive structure is implemented, with a high thermal conductivity silicone-based resin for the first layer and a silicone gel as the second layer, which is softer and has lower viscosity, to enhance heat transfer and stress relaxation, allowing for improved bonding and reduced void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high thermal conductivity adhesive with high filler content is used to bond the heater to the base plate, then thermal conductivity is improved, but viscosity increases making the adhesive difficult to apply and causing void formation
Solution Approach 1:
The adhesive layer is divided into two distinct layers: a first adhesive layer with high thermal conductivity and high filler content for heat transfer, and a second adhesive layer with lower viscosity for easy application and void elimination. This segmentation allows each layer to optimize its specific function without compromise
Solution Approach 2:
The patent uses a composite adhesive structure combining two different adhesive materials with complementary properties. The first layer uses a thermosetting adhesive with high filler content (50-90 wt%) for thermal conductivity, while the second layer uses a silicone-based adhesive with lower viscosity for workability, creating a composite system that achieves both thermal performance and ease of manufacture
2Temperature
If the adhesive layer is made thick to even out surface temperature, then temperature stabilization is improved, but void formation becomes more likely and thermal conductivity becomes uneven
Solution Approach 1:
The thick adhesive layer is segmented into two functional layers: the first layer provides the necessary thickness (0.5-2 mm) for temperature evening, while the second layer with lower viscosity ensures proper wetting and void elimination during bonding, maintaining reliability despite the overall thickness
Solution Approach 2:
Different regions of the adhesive structure have different properties: the first layer has high filler content and high viscosity optimized for thermal conductivity and temperature stabilization, while the second layer has lower viscosity optimized for wetting and void prevention, with each layer performing its specific local function
3Power
If high power heater is used for high temperature processing, then processing capability is improved, but cooling efficiency requirements increase and adhesive layer thermal conductivity becomes more critical
Solution Approach 1:
The composite adhesive structure with two layers optimizes the thermal conduction path from the high-power heater to the base plate, ensuring efficient heat removal. The first layer provides high thermal conductivity to handle the heat flux, while the second layer ensures complete contact and eliminates thermal resistance from voids
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 provides improved thermal conductivity and stress relaxation, enhancing the reliability of the electrostatic chuck by preventing peeling and simplifying the attachment process, while maintaining high workability and adhesion.
Implementation Method 1
the adhesive layer requires a material having high thermal conductivity
Implementation Method 2
an electrostatic chuck (substrate) is provided on the RF electrode, and the wafer is brought into tight contact with the electrostatic chuck
Data Source
AI summary
An electrostatic chuck has a structure in which a heater is sandwiched between a base member and an electrostatic chuck substrate, the heater being bonded to the base member with an adhesive layer interposing therebetween. The adhesive layer interposing between the heater and the base member has a structure in which a first adhesive layer and a second adhesive layer are stacked, the first adhesive layer being formed by curing an adhesive having high thermal conductivity, the second adhesive layer being formed as gel by curing an adhesive having lower viscosity than the adhesive of the first adhesive layer. Preferably, the first and second adhesive layers are both made of a silicone-based resin.