Transition Metal Oxynitride Adhesion Layer for Magnetic Head DLC Coating
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Solution Overview
Problem
Existing hard disk drive (HDD) technologies face challenges in maintaining ultra-low head-to-disk spacing while ensuring adequate protection against corrosion and wear, as conventional DLC coatings exhibit high internal stress and poor adhesion, leading to potential damage and data loss due to occasional contact between the magnetic head and disk.
Innovation Solution
A bilayer coating system utilizing transition metal oxynitrides (MeOxNy) as an adhesion enhancing and corrosion resistant underlayer, combined with a diamond-like carbon (DLC) overlayer, which reduces stress, improves adhesion, and provides electrical isolation, thereby minimizing noise and enhancing wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional DLC coating is applied to protect magnetic head and disk surfaces, then wear resistance and corrosion protection are improved, but internal stress increases and adhesion deteriorates
Solution Approach 1:
The protective coating system is segmented into multiple functional layers: a transition metal oxynitride adhesion layer (5-20 nm) beneath the DLC coating, and an optional intermediate layer. This segmentation allows each layer to optimize its specific function - the adhesion layer manages stress and bonding while the DLC provides wear resistance.
Solution Approach 2:
The invention uses composite material structures combining transition metal oxynitrides (TiOxNy, TaOxNy, etc.) with diamond-like carbon. This composite approach leverages the low-stress, high-adhesion properties of oxynitrides and the hard, wear-resistant properties of DLC, achieving both improved adhesion and maintained wear resistance.
2Length of moving object
If DLC coating thickness is reduced to meet fly height requirements, then head-to-disk spacing is improved, but protective capability deteriorates
Solution Approach 1:
The invention changes the physical and chemical parameters of the protective system by introducing transition metal oxynitride layers with specific composition ratios (x/y ratios) and thicknesses. This allows achieving adequate protection with reduced total coating thickness (5-30 nm) to meet sub-10 nm fly height requirements while maintaining or improving protective capability through optimized material properties.
3Strength
If adhesion layer thickness is increased to improve bonding, then adhesion is improved, but internal stress increases
Solution Approach 1:
The invention optimizes the thickness parameter of the adhesion layer to a specific range (5-20 nm) where it provides sufficient bonding strength while maintaining low internal stress. This parameter optimization, combined with the low-intrinsic-stress properties of transition metal oxynitrides, achieves improved adhesion without the stress problems associated with thicker adhesion layers.
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 transition metal oxynitride underlayer effectively reduces stress and noise, while the DLC overlayer provides robust protection against corrosion and wear, maintaining the integrity of magnetic heads and disks even at sub-30 angstrom thicknesses, thus addressing the limitations of prior art.
Implementation Method 1
transition metal oxynitride adhesion/corrosion barrier
Implementation Method 2
diamond-like carbon overcoat
Data Source
AI summary
A protective bilayer on a magnetic read/write head or magnetic disk is formed as an adhesion enhancing and corrosion resistant underlayer and a protective diamond-like carbon (DLC) overlayer. The underlayer is a transition metal oxynitride, having the general formula MeOxNy, where Me represents a single element or an alloy of the following transition metal elements: Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W, here x can be within the range between 0 and 3 and y is in the range between approximately 0 and 2. Adjusting the values of x and y contributes to such qualities of the protective bilayer as stress compensation, chemical and mechanical stability and low electrical conductivity. Methods of forming the adhesion layer, include reactive ion sputtering, plasma assisted chemical vapor deposition, pulsed laser deposition and plasma immersion ion implantation.