Sputtering Target Surface Area for Impedance Stability
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Solution Overview
Problem
High power sputtering devices require large and costly power supplies due to significant changes in current and voltage during the lifespan of the sputtering target, making it challenging to maintain uniform film thickness and deposition rate, and existing methods do not effectively control these changes or address the influence of target surface area on electrical circuit characteristics.
Innovation Solution
A sputtering target with an enlarged surface area, specifically between 100% to 125% of its original area, and a backing plate assembly with thicker concave portions to minimize impedance changes and heat stress, allowing for the use of a small-capacity power supply and maintaining film uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the surface area of the sputtering target is increased to minimize impedance changes, then the electrical stability is improved, but the film uniformity deteriorates
Solution Approach 1:
The target surface is designed with different regions having different properties: a central active sputtering region with optimized local area for good film uniformity, and additional peripheral areas contributing to overall impedance stability. This local differentiation allows simultaneous optimization of both film quality and electrical characteristics.
Solution Approach 2:
The target design transitions from a simple planar surface to a three-dimensional structure with varying depths and profiles. By controlling the depth and shape of target regions, the invention achieves both increased effective surface area for impedance stability and controlled projection area for film uniformity.
2Reliability
If a large-capacity power supply is used to handle significant current and voltage changes, then the reliability is improved, but the device cost increases
Solution Approach 1:
The target is pre-formed with a specific surface area and impedance characteristic before sputtering begins. This preliminary design of the target geometry ensures that the electrical circuit maintains stable impedance throughout the target's operational life, allowing the use of simpler, lower-capacity power supplies.
3Stability of the object's composition
If the surface area of the target is excessively enlarged, then the impedance change is minimized, but the film uniformity becomes inferior
Solution Approach 1:
The invention optimizes specific parameters including the target's surface area (100-125% of original), projection area, and depth-to-width ratio (0.1-0.5). By precisely controlling these parameters, the target achieves adequate surface area for impedance stability while maintaining projection area limits for film uniformity.
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 enables the use of an inexpensive, small-capacity power supply, minimizes impedance changes, and maintains film uniformity, while reducing heat stress and deformation issues under high power sputtering conditions, resulting in a cost-effective and efficient deposition system.
Implementation Method 1
self sputtering or high power sputtering for forming a uniform film
Data Source
AI summary
Provided is a tabular sputtering target on which an erosion portion and a non-erosion portion are formed, and the surface area thereof exceeds 100% but is less than 125% of the surface area when the target is assumed to be planar. Also provided is a tabular sputtering target on which an erosion portion and a non-erosion portion are formed comprising one or more concave portions on the target surface region, and the surface area thereof exceeds 100% but is less than 125% of the surface area when the target is assumed to be planar. An inexpensive, small-capacity power supply unit can be used by minimizing the electrical variations in the sputtering circuit as much as possible throughout the lifespan of the target through self sputtering or high power sputtering.