Sputtering Target Bonding via Selective Interface Treatment
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Solution Overview
Problem
Sputtering targets experience thermal stress and delamination due to mismatched coefficients of thermal expansion between the target material and the support body, leading to uneven heat dissipation and potential cracking during the sputtering process.
Innovation Solution
The solution involves selectively treating distinct areas of the support body and sputtering target to enhance the bonding strength of the bonding material, creating controlled areas of good and bad adhesion to manage thermal stresses and prevent delamination, using techniques like plasma treatment, grinding, or ultrasonic soldering to apply a low melting point solder like indium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If continuous bonding of target to backing body is used, then bonding strength is improved, but thermal stress and delamination occur due to mismatched coefficients of thermal expansion
Solution Approach 1:
The bonding interface is segmented into distinct bonded areas and non-bonded areas. The bonding material is applied only to specific regions rather than continuously across the entire interface, creating discrete bonding zones that reduce cumulative thermal stress while maintaining sufficient overall bonding strength.
Solution Approach 2:
Different regions of the bonding interface have different properties: some areas have bonding material applied for strong adhesion, while other areas are left without bonding material to act as stress relief zones. This local differentiation allows the structure to simultaneously achieve strong bonding where needed and stress accommodation where required.
2Reliability
If solder bridges are used to compensate for thermal expansion, then thermal stress is reduced, but device complexity increases
Solution Approach 1:
Instead of using complex solder bridge structures with spiral or ring grooves, the patent segments the bonding interface into simple bonded and non-bonded areas. This achieves thermal stress compensation through a much simpler configuration that eliminates the need for complex groove patterns and centrifugal casting processes.
3Strength
If selective superficial treatment is applied to enhance bonding, then bonding strength in distinct areas is improved, but manufacturing complexity increases
Solution Approach 1:
Selective superficial treatment such as plasma treatment, grinding, or sandblasting is applied only to specific areas where bonding material will be placed. This local treatment enhances bonding strength at critical interfaces without requiring treatment of the entire surface, thereby limiting the increase in manufacturing complexity to only the necessary regions.
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 approach reduces thermal stresses, prevents uncontrolled delamination, and allows for higher thermal loads, enhancing the durability and cost-effectiveness of sputtering targets by ensuring even heat dissipation and minimizing the need for expensive materials with lower coefficients of thermal expansion.
Implementation Method 1
a bonding material binding said back surface to said carrying surface
Implementation Method 2
whereby controlling delamination of the bonding material during solidification of the bonding material
Data Source
AI summary
A target assembly comprising—a support body having a carrying surface; —a sputtering target having an attaching surface, said carrying surface and said attaching surface being arranged in opposing facing relation to one another, thereby defining an intermediate space between said carrying surface and said attaching surface; and—a bonding material disposed in the intermediate space for binding said attaching surface to said carrying surface, —wherein distinct areas of one or both of said attaching surface and said carrying surface are selectively, superficially treated to enhance the bonding strength of said bonding material in said distinct areas.