Cu-Ca Alloy Sputtering Target Suppressing Abnormal Discharge
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Solution Overview
Problem
The increase in power during sputtering for high-definition TFT panels using Cu—Ca alloy sputtering targets often leads to abnormal discharge, causing particle generation and uneven film thickness, which affects productivity and film quality.
Innovation Solution
A Cu—Ca-based alloy sputtering target with controlled compositions, specifically 0.3 to 1.7% Ca, 5 ppm or less total Mg and Al, and 20 ppm or less oxygen, is used to suppress abnormal discharge, along with a manufacturing method involving high-purity copper melting and controlled addition of Ca in an inert atmosphere, followed by casting and stress relief annealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the power applied to sputtering is increased to increase the deposition rate, then productivity is improved, but abnormal discharge occurs more frequently
Solution Approach 1:
The patent changes the chemical composition parameters of the Cu—Ca alloy target by precisely controlling the Ca content (0.3 to 1.7 mass%) and limiting impurity levels (O: 20 ppm or less, Mg+Al: 5 ppm or less). This compositional parameter optimization suppresses abnormal discharge even at high sputtering power, enabling increased deposition rates without the harmful effects previously observed in conventional Cu—Ca alloys.
2Productivity
If the input power during sputtering is increased to improve productivity, then deposition rate is increased, but particle generation increases due to abnormal discharge
Solution Approach 1:
By optimizing the Cu—Ca alloy composition (Ca: 0.3 to 1.7 mass%, O: 20 ppm or less, Mg+Al: 5 ppm or less), the patent enables high-power sputtering without abnormal discharge. This maintains film quality and prevents particle generation while achieving high deposition rates, thus resolving the contradiction between productivity improvement and manufacturing precision.
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 solution effectively prevents abnormal discharge during high-power sputtering, ensuring even film thickness and improved adhesion properties, enhancing productivity and film quality with reduced specific resistance and cost.
Implementation Method 1
a copper alloy sputtering target used as a target during sputtering for forming a copper alloy film
Implementation Method 2
melting the copper by high frequency induction heating in a crucible in an inert gas atmosphere or a reducing gas atmosphere so as to obtain a molten copper
Data Source
AI summary
A copper alloy sputtering target is formed by a copper alloy including the content of Ca being 0.3 to 1.7% by mass, the total content of Mg and Al being 5 ppm or less by mass, the content of oxygen being 20 ppm or less by mass, and the remainder is Cu and inevitable impurities. A manufacturing method of a copper alloy sputtering target comprises steps of: preparing a copper having purity of 99.99% or more by mass; melting the copper so as to obtain a molten copper; controlling components so as to obtain a molten metal having a predetermined component composition by the addition of Ca having a purity of 98.5% or more by mass into the molten copper and by melting theCa; casting the molten metal so as to obtain an ingot; and performing stress relieving annealing after performing hot rolling to the ingot.