Integrated Copper Sputtering Target for Warpage-Resistant Deposition
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Solution Overview
Problem
Integrated sputtering targets made of copper or copper alloys face issues with warpage due to lower hardness, which can lead to difficulties in continued use and film uniformity during sputtering.
Innovation Solution
The sputtering target is manufactured by integrating a target portion and a backing plate portion made of copper and unavoidable impurities, with a Vickers hardness of 90 or more and a flat ratio of crystal grains between 0.35 and 0.65, achieved through a process involving melt casting, hot forging, cold rolling or forging, heat treatment, and additional cold rolling or forging with controlled strain introduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an integrated sputtering target is made of copper or copper alloy with the same material for both target portion and backing plate portion, then the number of manufacturing steps is decreased and costs are reduced, but the hardness of the target is lower compared to separate type targets
Solution Approach 1:
The patent applies parameter changes by controlling the crystal grain structure (flat ratio between 0.3 and 0.7) and introducing strain through specific hot forging and cold rolling processes to achieve high hardness (Hv 90 or more) in the integrated copper target, resolving the contradiction between ease of manufacture and hardness
2Reliability
If the hardness of the integrated sputtering target is lower, then warpage occurs during sputtering, but increasing hardness by using separate materials increases manufacturing complexity
Solution Approach 1:
The patent merges the target portion and backing plate portion into a single integrated copper structure, eliminating the need for bonding separate components. The manufacturing process combines hot forging and cold rolling steps to achieve the required hardness and prevent warpage while maintaining structural integration, thus avoiding the complexity of multi-material assembly
3Duration of action of moving object
If the target material is made thinner to compensate for backing plate thickness in separate type targets, then the life of the target is shortened, but using thicker material in integrated targets increases manufacturing difficulty
Solution Approach 1:
The patent changes the manufacturing parameters by implementing a multi-stage process with hot forging followed by controlled cold rolling with specific reduction ratios. This enables the production of thicker integrated targets with adequate hardness (Hv 90 or more) and appropriate crystal grain structure, thereby extending target life without excessive manufacturing difficulty
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 effectively prevents warpage during sputtering, maintains film uniformity, and extends the usable life of the sputtering target by ensuring high hardness and appropriate crystal grain structure.
Implementation Method 1
a thin film of copper or a copper alloy is usually formed by means of sputtering
Implementation Method 2
the ingot is subjected to hot forging, first cold rolling or first cold forging, a heat treatment, and second cold rolling or second cold forging
Data Source
AI summary
A sputtering target according to one embodiment is an integrated sputtering target comprising a target portion and a backing plate portion, both of them being made of copper and unavoidable impurities, wherein a Vickers hardness Hv is 90 or more, and wherein a flat ratio of crystal grains in a cross section orthogonal to a sputtering surface is 0.35 or more and 0.65 or less.