Substrate Carrier Composite Bar for Sputter Edge Exclusion
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Solution Overview
Problem
Substrates with different coefficients of thermal expansion than their carriers experience nonuniform coating at the margins during sputter processes, leading to 'edge exclusion' where peripheral regions are not coated.
Innovation Solution
A substrate carrier comprising materials with varying coefficients of thermal expansion, featuring a central bar of lower expansion material like titanium connected to a frame of higher expansion material like aluminum, ensures uniform coating by maintaining substrate centrality during temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the carrier is made of a material with high coefficient of thermal expansion (e.g., aluminum), then the carrier is lightweight and cost-effective, but the substrate experiences nonuniform coating at the margins due to differential thermal expansion
Solution Approach 1:
The carrier is constructed as a composite structure combining aluminum (high thermal expansion coefficient) for the main body to maintain lightweight and cost-effective properties, with a centering means made of material having lower thermal expansion coefficient (or matched to substrate) to maintain dimensional stability and ensure uniform substrate coating during thermal cycles
2Device complexity
If the carrier uses a single material with high thermal expansion, then the structure is simple, but the substrate positioning becomes unstable during temperature changes causing edge exclusion
Solution Approach 1:
The carrier combines different materials with complementary thermal expansion properties - aluminum provides structural simplicity and cost-effectiveness while the integrated centering means made of low-expansion material ensures reliable substrate positioning stability during temperature changes
3Ease of manufacture
If the carrier is made of aluminum with high thermal expansion, then the manufacturing cost is reduced, but the coating quality at substrate edges deteriorates due to differential expansion
Solution Approach 1:
The carrier uses a composite construction where aluminum provides cost-effective manufacturing and the integrated centering means made of material with matched thermal expansion properties to substrate ensures high coating quality at substrate edges by preventing differential expansion misalignment
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 combination of high-expansion aluminum with low-expansion materials like titanium reduces 'edge exclusion' by minimizing the substrate's movement relative to the carrier, resulting in more uniform coating across the substrate's margins.
Implementation Method 1
If the substrates held in frames have a coefficient of thermal expansion different from that of the frames, the substrates may be covered at the margins nonuniformly and onesidedly to too high a degree
Implementation Method 2
This bar has a coefficient of thermal expansion lower than the region of the carrier at which it is fastened
Data Source
AI summary
A carrier for a substrate, wherein at least a part of the carrier contains a material with a coefficient of thermal expansion which is higher than the coefficient of thermal expansion of the substrate, wherein in a specified region of the carrier a bar is centrally fastened whose coefficient of thermal expansion is lower than that of the region on which it is fastened.