Pot-Shaped Copper Sputtering Target Uniform Hardness
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Solution Overview
Problem
The existing methods for manufacturing copper sputtering targets with a pot-shaped structure face challenges in achieving uniform hardness and crystal orientation, leading to deformation and poor sputtering quality due to variations in crystal grain size and orientation, which affect the sputter rate and film quality.
Innovation Solution
The process involves hot forging, preforming, recrystallization annealing, and die forging to achieve uniform crystal grain size and orientation, specifically targeting a Vickers hardness of 70 or greater and a (220) primary crystalline orientation, ensuring consistent strength and reduced particle generation during sputtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional die forging is used to manufacture pot-shaped copper targets, then the target can be formed into the required three-dimensional structure, but the crystal grain size and hardness become non-uniform across different locations
Solution Approach 1:
The patent applies preliminary hot forging before die forging to create a more uniform initial structure. The hot forging process is performed first to destroy the cast structure and create a more homogeneous material distribution, which then serves as a better starting point for the subsequent die forging process, reducing the non-uniformity that would otherwise occur during the final shaping operation.
Solution Approach 2:
The patent employs multiple annealing treatments with different parameters (temperatures and durations) to control crystal grain growth. By carefully selecting annealing temperatures and holding times, the patent achieves uniform crystal grain size and hardness throughout the target, counteracting the non-uniformity introduced by the die forging process.
2Strength
If locations strongly affected by plastic deformation undergo recrystallization annealing, then crystal grains are refined at those locations, but this creates significant variation in crystal orientation and hardness across the target
Solution Approach 1:
The patent applies different heat treatment parameters to different regions of the target based on their deformation history. Locations with strong plastic deformation receive annealing treatment optimized for grain refinement, while less deformed areas receive treatment optimized for maintaining their structure, achieving local optimization rather than uniform treatment.
Solution Approach 2:
The patent performs preliminary hot forging before die forging to create a more uniform initial structure. This preliminary action reduces the deformation gradient between different locations, so that subsequent annealing produces more uniform crystal grain characteristics across the entire target.
3Shape
If the flange portion is made with conventional manufacturing methods, then the target can be formed, but the flange lacks sufficient strength and deforms due to creep phenomenon
Solution Approach 1:
The patent applies preliminary hot forging and multiple annealing treatments before the final die forging operation. This preliminary treatment creates a more uniform and refined crystal structure throughout the material, including the flange portion, which then provides better strength and creep resistance during subsequent processing and service.
Solution Approach 2:
The patent uses specific annealing temperature and time parameters to control the crystal grain structure in the flange region. By optimizing these thermal parameters, the patent achieves fine, uniform crystal grains in the flange that provide the necessary strength and resistance to deformation.
4Ease of manufacture
If coarsened crystal grains exist in the target, then the manufacturing process is simpler, but arc generation and particle generation increase during sputtering
Solution Approach 1:
The patent employs controlled annealing parameters (temperature and time) to achieve the desired crystal grain size without excessive coarsening. By carefully selecting and optimizing these thermal processing parameters, the patent maintains fine, uniform crystal grains that reduce arc and particle generation during sputtering while keeping the manufacturing process practical and efficient.
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 results in a copper sputtering target with uniform hardness and refined crystal grains, preventing deformation and improving sputtering quality by reducing particle generation and extending target life.
Implementation Method 1
Hot forging of the ingot or the billet will destroy the cast structure, diffuse and eliminate air holes and segregation, and, through recrystallization annealing, it is possible to increase the density and strength of the structure to a certain degree.
Implementation Method 2
through recrystallization annealing, it is possible to increase the density and strength of the structure to a certain degree.
Implementation Method 3
Since there will be locations that will be severely affected and locations that will hardly be affected by the plastic deformation during the die forging to be performed in the manufacture of the target
Implementation Method 4
recrystallization annealing and stress-relieving annealing are performed after die forging
Implementation Method 5
a standard planar target is deposited by colliding Ar ions against a target and beating out metal atoms
Implementation Method 6
with ionization sputtering, although the process is the same as a planar target up to colliding Ar ions against a target and beating out metal atoms, the metal atoms are ionized with dense plasma, whereby directivity can be given to the ionized metal atoms
Data Source
AI summary
Provided is a pot-shaped copper sputtering target manufactured with die forging, wherein the Vickers hardness Hv at all locations of the inner surface of the pot-shaped target is 70 or greater. With this pot-shaped copper sputtering target, the average crystal grain size in the target structure is 65 μm or less. Further, the inner surface of the pot-shaped target comprises crystalline orientations of (220), (111), (200), (311) obtained by X-ray diffraction, and the crystalline orientation of the face subject to erosion of the pot-shaped target is of a (220) primary orientation. An object of the present invention is to obtain a manufacturing method of a high quality sputtering target by improving and devising the forging process and heat treatment process to make the crystal grain size refined and uniform, and to obtain a high-quality sputtering target.