Sputtering Target Backside Channels for Thermal Stress Control
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Solution Overview
Problem
Conventional sputtering targets experience uneven cooling and thermal stress, leading to erosion grooves and microcracks, which result in reduced sputtering yields and particle contamination due to inadequate heat removal and spatial uniformity.
Innovation Solution
A sputtering target design featuring a sputtering plate with radially inner, middle, and outer regions, including concentric circular grooves and intersecting arcuate or linear channels on its backside surface, combined with an annular-shaped backing plate, enhances heat transfer and fluid dynamics to improve cooling efficiency and reduce thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional cooling systems are used with sputtering targets, then the cooling system structure is simple, but the heat removal efficiency is insufficient and spatial uniformity is poor
Solution Approach 1:
The cooling system is segmented into multiple independent cooling channels (first cooling channel, second cooling channel, third cooling channel) that are distributed across different regions of the sputtering target backside. This segmentation allows each channel to independently cool specific hot spots, significantly improving overall heat removal efficiency while maintaining structural simplicity through modular channel design
Solution Approach 2:
Different cooling channels are positioned in different radial regions (inner, middle, outer regions) of the sputtering target backside to provide localized cooling where heat generation varies. The first cooling channel serves the inner region, the second serves the middle region, and the third serves the outer region, ensuring spatially uniform heat removal across the entire target surface
2Ease of manufacture
If conventional cooling systems are used with sputtering targets, then the cooling system structure is simple, but spatial uniformity of heat removal is poor
Solution Approach 1:
The cooling system is divided into three distinct cooling channels positioned in specific radial regions of the sputtering target backside. This segmentation enables independent control and optimization of cooling in each region, achieving spatially uniform heat removal across the entire target surface while maintaining the simplicity of a channel-based structure
Solution Approach 2:
The cooling channels are asymmetrically distributed across the sputtering target backside, with the first cooling channel in the inner region, the second in the middle region, and the third in the outer region. This asymmetric placement optimizes heat removal for the non-uniform heat generation pattern typical in sputtering processes, achieving spatial uniformity without requiring symmetric channel arrangements
3Productivity
If higher power densities are applied to sputtering targets, then deposition rates improve, but thermal stress increases causing erosion grooves and microcracks
Solution Approach 1:
The backside of the sputtering target is segmented into multiple cooling zones with dedicated cooling channels positioned in inner, middle, and outer regions. This segmentation enables targeted cooling of high-stress areas, allowing higher power densities to be applied during sputtering without causing thermal stress-induced erosion grooves or microcracks, thus maintaining target structural integrity while improving deposition rates
Solution Approach 2:
Cooling channels are pre-positioned in the backside of the sputtering target before the sputtering process begins. This preliminary placement of cooling infrastructure ensures that thermal stress is managed proactively during high-power operation, preventing the formation of erosion grooves and microcracks before they can develop, thereby maintaining target reliability at higher deposition rates
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 design achieves more uniform cooling, reduces particle contamination, and allows for higher power densities and improved deposition rates by increasing the cooling surface area and promoting fluid circulation, thereby maintaining the sputtering target at cooler temperatures.
Implementation Method 1
A cooling system passes heat transfer fluid through a housing surrounding the rotatable magnets to cool the magnets and the underlying sputtering target
Implementation Method 2
The circular grooves and arcuate channels enhance heat transfer and fluid dynamics to improve cooling efficiency
Data Source
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AI summary
Implementations of the present disclosure relate to a sputtering target for a sputtering chamber used to process a substrate. In one implementation, a sputtering target for a sputtering chamber is provided. The sputtering target comprises a sputtering plate with a backside surface having radially inner, middle and outer regions and an annular-shaped backing plate mounted to the sputtering plate. The backside surface has a plurality of circular grooves which are spaced apart from one another and at least one arcuate channel, or linear channels, cutting through the circular grooves and extending from the radially inner region to the radially outer region of sputtering plate. The annular-shaped backing plate defines an open annulus exposing the backside surface of the sputtering plate.