Sample Holder Adhesive Layer Design for Thermal Stress Management
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Solution Overview
Problem
Existing sample holders for semiconductor wafers and liquid crystal display devices face challenges in maintaining thermal uniformity and durability during manufacturing processes like plasma etching, due to thermal stress and potential cracking between insulating substrates and heat-generating resistors, as well as between these substrates and metal members.
Innovation Solution
A sample holder design featuring an insulating ceramic substrate with a heat-generating resistor and a metal member bonded by an adhesive layer with distinct elastic modulus layers, where a higher elastic modulus first layer contacts the substrate and a lower elastic modulus second layer contacts the metal member, along with a layered and annular portion configuration to absorb forces and reduce thermal stress, enhancing bonding reliability and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer adhesive structure is used to bond the metal member to the insulating substrate, then the structure is simple and easy to manufacture, but thermal stress concentration occurs during thermal cycles causing cracking and peeling
Solution Approach 1:
The adhesive layer is divided into two distinct layers: a first adhesive layer with higher elastic modulus in contact with the insulating substrate, and a second adhesive layer with lower elastic modulus in contact with the metal member. This segmentation allows each layer to perform its specific function - the first layer provides strong bonding to the substrate while the second layer absorbs thermal stress, thereby preventing cracking and peeling during thermal cycles.
Solution Approach 2:
Different regions of the adhesive structure are assigned different elastic moduli to match the local requirements. The first adhesive layer near the insulating substrate has higher elastic modulus for strong adhesion, while the second adhesive layer near the metal member has lower elastic modulus for stress absorption. This local quality differentiation optimizes both bonding strength and stress resistance at each interface.
2Device complexity
If thermal stress is not properly managed in the adhesive layer, then the structure remains simple, but cracking and peeling occur between the metal member and insulating substrate
Solution Approach 1:
The second adhesive layer with lower elastic modulus is positioned beforehand between the metal member and the first adhesive layer to act as a cushioning layer. This layer anticipates and absorbs the thermal stress that will occur during thermal cycles, preventing the stress from concentrating at the critical interface between the metal member and insulating substrate, thereby preventing cracking and peeling before they can occur.
3Ease of manufacture
If the adhesive layer does not have differentiated elastic modulus, then manufacturing is easier, but thermal uniformity deteriorates during heating
Solution Approach 1:
The adhesive layer is segmented into two layers with different elastic moduli to optimize thermal management. The first adhesive layer with higher elastic modulus provides structural support and strong bonding, while the second adhesive layer with lower elastic modulus allows for thermal expansion accommodation, ensuring uniform heat distribution across the metal member and insulating substrate interface during heating processes.
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 design effectively reduces the likelihood of cracking and peeling, improves thermal uniformity, and enhances the durability of the sample holder by distributing thermal stress and efficiently transferring heat, thereby improving the reliability and longevity of the sample holder during thermal cycles.
Implementation Method 1
an adhesive layer covering the another main surface, the adhesive layer including a first layer which is in contact with the insulating substrate, and a second layer which is in contact with the metal member and having an elastic modulus that is smaller than an elastic modulus of the first layer
Implementation Method 2
a heat-generating resistor located on another main surface of the insulating substrate
Data Source
AI summary
A sample holder includes an insulating substrate including a ceramic material and having a sample holding surface on one main surface thereof, a heat-generating resistor located on another main surface of the insulating substrate, a metal member facing the another main surface, and an adhesive layer covering the another main surface, the adhesive layer including a first layer which is in contact with the insulating substrate, and a second layer which is in contact with the metal member and having an elastic modulus that is smaller than an elastic modulus of the first layer, the second layer including a layered portion positioned between the first layer and the metal member, and an annular portion surrounding the first layer.