Ramp-Profile Sputtering Target for Film Thickness Uniformity
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Solution Overview
Problem
The existing sputtering targets face significant degradation in film thickness uniformity, particularly at the final stage of sputtering, due to intense erosion in areas with high horizontal magnetic field strength, leading to non-uniform deposition on substrates.
Innovation Solution
A sputtering target with a ramp on its surface is designed to reduce the thickness of the target material at positions where erosion intensively concentrates, specifically at areas with maximum horizontal magnetic field strength, to redistribute erosion and improve film thickness uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the thickness of target material is increased to prolong life, then the service life of sputtering target is improved, but the film thickness uniformity deteriorates due to decreased TS distance and intense erosion concentration
Solution Approach 1:
The target material is designed with non-uniform thickness distribution, featuring a ramp structure where the thickness varies in the radial direction. Specifically, the thickness is reduced at positions where erosion concentrates most intensively (typically at a radial position of 60-90% of the target radius). This local variation in thickness compensates for the intense erosion in high magnetic field regions, maintaining a more uniform film thickness on the substrate throughout the target's service life.
2Productivity
If erosion concentrates in high magnetic field strength regions, then deposition rate is enhanced in those areas, but film thickness uniformity on substrate deteriorates with significant increase in middle part and decrease in end part
Solution Approach 1:
The ramp structure creates local variations in target thickness that correspond to the spatial distribution of erosion rates. By reducing thickness at specific radial positions (60-90% of radius), the design ensures that these regions erode more uniformly over time, preventing excessive material removal that would otherwise cause film thickness non-uniformity on the substrate.
Solution Approach 2:
The ramp structure is pre-formed in the target material before sputtering begins. This preliminary geometric modification anticipates the erosion pattern that will develop during sputtering, allowing the target to maintain optimal thickness distribution throughout its operational life and ensuring consistent film deposition characteristics.
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 ramp design effectively shifts erosion to the edge of the target, ensuring more uniform deposition across the substrate, maintaining excellent film thickness uniformity at both the initial and final stages of sputtering.
Implementation Method 1
Sputtering is a process in which an inert gas such as argon is introduced under vacuum and a high voltage is applied between a substrate and a target material to thereby collide the inert gas being plasmatized (or being ionized) with the target material and to sputter target atoms included in the target material, leading to deposition of the sputtered atoms on the substrate to form a thin film on the substrate.
Implementation Method 2
there has generally been known magnetron sputtering in which a magnet is arranged on the back side of a sputtering face of the target material (i.e., face of a side where the inert gas made into plasma (or being ionized) is brought into collision in the target material), thereby enhancing a deposition rate.
Data Source
AI summary
A sputtering target comprising a target material, wherein a sputtering face of the target material has a ramp provided to reduce a thickness of the target material at a position where erosion concentrates most intensively during sputtering.