Disk Shield for Uniform Carbon Layer in Plasma CVD
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Solution Overview
Problem
Existing plasma CVD methods for forming carbon protective layers on magnetic recording media result in nonuniform in-plane film thickness distribution, which affects electromagnetic conversion characteristics and reliability, such as corrosion resistance.
Innovation Solution
An apparatus and method using an annular-shaped plasma beam generation source and a disk-shaped shield, where the shield is positioned between the plasma source and substrate, with specific distance and radius configurations to achieve a more uniform film thickness distribution, utilizing the equation x=[{R/(R+A)}+B]·L to optimize the placement of the disk-shaped shield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a plasma CVD method is used to form a carbon protective layer, then the film density and hardness are improved, but the in-plane distribution of film thickness becomes nonuniform
Solution Approach 1:
A disk-shaped shield is introduced as an intermediary component between the plasma beam generation source and the substrate. The shield has a specific radius (0.3 to 0.7 times the plasma source radius) and is positioned at a specific distance (0.2 to 0.5 times the plasma source-to-substrate distance) to block excessive plasma flux in the central region, thereby uniformizing the film thickness distribution while preserving the benefits of plasma CVD
Solution Approach 2:
The invention applies local quality modification by creating different plasma flux conditions in different regions of the substrate. The disk-shaped shield selectively blocks plasma in the central zone while allowing it to reach the peripheral regions, resulting in uniform film deposition across the entire substrate surface
2Productivity
If the film thickness is reduced to increase recording density, then the distance between head element and magnetic recording layer is decreased, but the reliability such as corrosion resistance cannot be ensured in thin places
Solution Approach 1:
The invention uses plasma flow control through the disk-shaped shield to achieve uniform film thickness distribution. By regulating the plasma flux distribution, the method enables formation of uniformly thin films that maintain adequate thickness (5-20 nm) across the entire substrate, ensuring corrosion resistance while enabling high recording density
3Manufacturing precision
If a shield is disposed in the vicinity of the central zone to make film thickness more uniform, then the in-plane distribution of film thickness is improved, but further improvements are needed to obtain a more uniform film thickness
Solution Approach 1:
The invention optimizes specific parameters of the disk-shaped shield (radius ratio of 0.3-0.7 and distance ratio of 0.2-0.5 relative to plasma source dimensions) to achieve uniform film thickness distribution. These parameter ranges provide a robust solution that reduces film thickness variation to less than 6% across the substrate
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 solution effectively reduces the in-plane distribution of film thickness variation to less than 6%, ensuring consistent electromagnetic conversion characteristics and reliability across the substrate, without significantly decreasing the film formation rate.
Implementation Method 1
apparatus and method for forming a carbon protective layer on a substrate, such as for a magnetic recording medium, by a plasma CVD method
Data Source
AI summary
An apparatus and method for forming a carbon protective layer on a substrate using a plasma CVD method allows a more uniform in-plane distribution of the carbon protective layer thickness. The apparatus includes an annular anode that generates a plasma beam and a disk-shaped shield disposed between the anode and the substrate. The anode, the shield, and the substrate are concentrically arranged so that a straight line connecting the centers of the anode and the substrate is perpendicular to the deposition surface of the substrate where the carbon protective layer is to be formed. The center of the shield is also on the straight line.