Cylindrical Copper Sputtering Target Grain Boundary Control
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Solution Overview
Problem
The formation of abnormal electrical discharges during sputtering with cylindrical targets can lead to non-uniform film thickness and particle generation, making it difficult to achieve stable film formation.
Innovation Solution
A cylindrical sputtering target material with a copper or copper alloy composition, where the special grain boundary length ratios are optimized, and impurity levels of Si, C, and O are controlled to prevent abnormal electrical discharges, ensuring a uniform sputtering surface and stable film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a cylindrical sputtering target is used for continuous film formation, then productivity is improved, but abnormal electrical discharge occurs due to foreign materials and impurities
Solution Approach 1:
The invention changes the microstructural parameters of the target material by controlling the grain boundary characteristics (specifically achieving a special grain boundary length ratio LσN/LN of 0.2 or more) and impurity content (Si+C≤10 ppm, O≤50 ppm). This parameter optimization prevents abnormal electrical discharge while maintaining the cylindrical target's continuous film formation capability, thus resolving the contradiction between productivity and reliability
Solution Approach 2:
The invention creates an optimized composite structure within the copper or copper alloy target by controlling the distribution and characteristics of grain boundaries and impurities. The specific grain boundary configuration (LσN/LN ≥ 0.2) combined with controlled impurity levels creates a composite microstructure that enhances electrical discharge stability while maintaining high productivity
2Productivity
If high power sputtering is performed to improve productivity, then film formation efficiency is improved, but abnormal electrical discharge occurs more frequently
Solution Approach 1:
The invention modifies the material parameters (grain boundary length ratio LσN/LN ≥ 0.2 and controlled impurity levels) to increase the threshold power for abnormal electrical discharge. This allows high-power sputtering to be performed at higher productivity levels without triggering abnormal electrical discharge, effectively resolving the contradiction between film formation speed and discharge stability
3Ease of manufacture
If the target material contains impurities to facilitate manufacturing, then ease of manufacture is improved, but abnormal electrical discharge occurs and manufacturing precision deteriorates
Solution Approach 1:
The invention establishes specific parameter thresholds for impurity content (Si+C≤10 ppm, O≤50 ppm) and grain boundary characteristics (LσN/LN ≥ 0.2) that balance manufacturability with film uniformity. These parameter specifications enable the production of targets that can be manufactured with controlled impurity levels while ensuring uniform wiring film thickness without abnormal electrical discharge
Solution Approach 2:
The invention creates a standardized model for target material composition and microstructure (specific grain boundary length ratio and impurity levels) that can be replicated in manufacturing. This copying of the optimized microstructural parameters ensures consistent film uniformity across different production batches while maintaining ease of manufacture
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 optimized target material prevents abnormal electrical discharges, ensuring consistent film formation and high-power sputtering efficiency by maintaining uniform crystal grain boundaries and low impurity levels, resulting in a stable and uniform thin film.
Implementation Method 1
A sputtering method using a sputtering target is generally used when forming such a wiring film (thin film) of copper or a copper alloy on a substrate
Data Source
AI summary
Provided is a cylindrical sputtering target material formed of copper or a copper alloy, in which an average value of the special grain boundary length ratios LσN/LN which are measured with respect to the outer peripheral surfaces of both end portions and the outer peripheral surface of the center portion in an axis O direction is set to be equal to or greater than 0.5, and each measured value is in a range of ±20% with respect to the average value of the special grain boundary length ratios LσN/LN, and the total amount of Si and C which are impurity elements is equal to or smaller than 10 mass ppm and the amount of O is equal to or smaller than 50 mass ppm.