Sputtering Target-Backing Plate Assembly with Controlled Proof Stress
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Solution Overview
Problem
Conventional sputtering target-backing plate assemblies experience plastic deformation due to thermal expansion and contraction, leading to non-uniform film thickness and fluctuating deposition rates, which affects the productivity and quality of the sputtering process.
Innovation Solution
A sputtering target-backing plate assembly is designed with a tantalum target having a 0.2% proof stress of 150 to 200 MPa and a copper alloy backing plate with a 0.2% proof stress of 60 to 200 MPa, where the backing plate contains 30 to 40 at% Zn, to inhibit plastic deformation and maintain uniformity despite differing thermal expansion coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sputtering power is increased to increase the deposition rate, then the deposition rate increases, but the target temperature increases causing plastic deformation
Solution Approach 1:
The patent changes the material parameters of the backing plate by specifying precise compositional ranges (Cu: 58-67 wt%, Zn: 25-35 wt%, Si: 3-8 wt%) and mechanical property parameters (0.2% proof stress ≥180 MPa, elongation ≥10%) to optimize thermal management while maintaining structural integrity during high-power sputtering operations
Solution Approach 2:
The patent employs a composite backing plate material system combining copper, zinc, and silicon in specific proportions to achieve superior thermal conductivity and mechanical strength, allowing the target to withstand high temperatures without plastic deformation while maintaining high deposition rates
2Manufacturing precision
If the rotation speed of the magnet is increased to improve mixing, then the deposition uniformity improves, but eddy current increases causing reverse magnetic field and flux reduction
Solution Approach 1:
The patent optimizes the magnetic flux density parameter (0.3-0.6 T) and magnet rotation speed (300-600 rpm) to achieve effective plasma mixing while minimizing eddy current generation, balancing film uniformity with energy efficiency
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 configuration significantly reduces plastic deformation, enhances film thickness uniformity, and increases deposition rates by controlling thermal expansion and contraction, thereby improving the overall productivity of the sputtering process.
Implementation Method 1
a sputtering target is bonded with a backing plate that is prepared from a material having favorable thermal conductivity such as copper, and this backing plate is configured to be cooled via means such as water-cooling so as to indirectly cool the sputtering target
Implementation Method 2
the sputtering target-backing plate assembly is subject to plastic deformation as a result of repeating the deformation caused by the thermal expansion and contraction as a bimetal
Implementation Method 3
an eddy current is generated when the magnet is rotated in the cooling device, and the eddy current increases together with the increase in the speed of rotation. In addition, a reverse magnetic field is generated due to the eddy current, and the generated reverse magnetic field functions to reduce the equivalent magnetic flux
Data Source
AI summary
The present invention is a sputtering target-backing plate assembly in which the sputtering target is made from Ta having a 02% proof stress of 150 to 200 MPa, and the backing plate is made from a Cu alloy having a 0.2% proof stress of 60 to 200 MPa. The present invention aims to increase the uniformity of the film thickness as well as increase the deposition rate and improve the productivity by reducing, as much as possible, the plastic deformation of the sputtering target caused by the repeated thermal expansion and contraction of the sputtering target-backing plate assembly as a bimetal.