Tantalum Sputtering Target Grain Control for Voltage Drift
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Solution Overview
Problem
Existing tantalum sputtering targets face challenges in reducing discharge voltage and suppressing voltage drift during deposition, which affects plasma generation and film uniformity, particularly in forming effective diffusion barrier layers for copper wiring in semiconductor devices.
Innovation Solution
A method to produce a tantalum sputtering target with controlled crystal grain size and orientation, specifically adjusting the average crystal grain size to 50 µm to 150 µm and increasing the (200) plane orientation rate while reducing the (222) plane orientation rate, to stabilize plasma and reduce discharge voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional tantalum sputtering targets are used, then copper wiring can be deposited, but discharge voltage is high and voltage drift occurs during deposition
Solution Approach 1:
The patent applies parameter changes by controlling the crystal grain size (50-150 μm) and crystal orientation ((200) plane 40-80%, (222) plane 20-60%) of the tantalum target. These microstructural parameter changes optimize the sputtering characteristics, reducing discharge voltage and suppressing voltage drift during deposition, thereby improving plasma generation stability.
2Reliability
If crystal grain size and orientation are controlled to reduce discharge voltage, then plasma stability improves, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-controlling the crystal grain size and orientation during target manufacturing before sputtering. The tantalum target is produced with specific microstructural parameters (grain size 50-150 μm, (200) orientation 40-80%, (222) orientation 20-60%) through controlled solidification and heat treatment processes, so that the optimal plasma stability is achieved without requiring complex real-time adjustments during deposition.
3Use of energy by moving object
If (200) plane orientation is increased and (222) plane orientation is reduced, then discharge voltage decreases, but film uniformity may be affected
Solution Approach 1:
The patent applies parameter changes by establishing specific ranges for crystal orientation: (200) plane at 40-80% and (222) plane at 20-60%. These optimized parameter combinations reduce discharge voltage while maintaining film thickness uniformity within acceptable tolerances (±5%). The balanced orientation distribution ensures both low discharge voltage and uniform film deposition.
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 method effectively reduces discharge voltage, suppresses voltage drift, and improves plasma stability, enhancing the formation of Ta or TaN films as diffusion barrier layers to prevent copper contamination in semiconductor devices.
Implementation Method 1
a Ta film or a TaN film is deposited by sputtering a tantalum target
Data Source
AI summary
A tantalum sputtering target, wherein, on a sputtering surface of the tantalum sputtering target, an average crystal grain size is 50 µm or more and 150 µm or less, and a variation in a crystal grain size is 30 µm or less. A tantalum sputtering target, wherein, on a sputtering surface of the tantalum sputtering target, an orientation rate of a (200) plane exceeds 70%, an orientation rate of a (222) plane is 30% or less, an average crystal grain size is 50 µm or more and 150 µm or less, and a variation in a crystal grain size is 30 µm or less. By controlling the crystal grain size of the target, or the crystal grain size and the crystal orientation of the target, effects are yielded in that the discharge voltage of the tantalum sputtering target can be reduced so that plasma can be more easily generated, and the voltage drift during deposition can be suppressed.