TDMR Read Head TaOx Layer for Flat Middle Shield Topography
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Solution Overview
Problem
The topography issues in dual free layer (DFL) two-dimensional magnetic recording (TDMR) read heads, caused by dielectric refill surrounding the lower reader, limit down track spacing and misalignment of readers, affecting the accessibility of disk data in TDMR mode.
Innovation Solution
A method involving the deposition of a dielectric layer around the lower reader, followed by ion milling to create a substantially flat layer that tapers down, and the optional use of a TaOx layer to form a planar surface, allowing for the formation of middle and upper shields that are also flat, thereby addressing the topography issues and improving reader alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a thicker RHB structure is used to achieve the desired transverse bias field, then the transverse bias field is improved, but the topography along the reader stripe height increases
Solution Approach 1:
The patent applies local quality by making the dielectric refill layer have different thicknesses at different locations - thicker near the RHB structure and progressively thinner toward the outer perimeter. This gradient thickness distribution allows the structure to provide magnetic shielding where needed while minimizing topography variations in other areas, resolving the contradiction between achieving sufficient bias field and controlling topography.
2Stability of the object's composition
If the dielectric refill surrounding the lower reader is made to fill gaps completely, then the structural integrity is improved, but the topography is increased and limits narrower DTS
Solution Approach 1:
The dielectric refill layer is designed with non-uniform thickness, being thicker near the lower reader structure where structural support is needed and progressively thinner toward the outer perimeter. This local variation allows the layer to maintain structural integrity where required while minimizing overall topography that would interfere with down track spacing.
Solution Approach 2:
The patent addresses the topography issue by introducing a vertical dimension variation within the dielectric refill layer itself, creating a thickness gradient from the inner region near the reader to the outer region. This dimensional change allows the same layer to serve both structural and topography-control functions simultaneously.
3Shape
If asymmetric readers with different over mill depths are used to address middle shield topography, then the down track spacing is improved, but the device complexity increases
Solution Approach 1:
The patent applies asymmetry in the form of an asymmetric thickness distribution within the dielectric refill layer, with the layer being thicker near the RHB structure and thinner toward the outer perimeter. This asymmetric design allows the middle shield to achieve flat topography and narrow down track spacing while avoiding the need for completely asymmetric reader structures, thus managing device complexity.
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 enhances the read head's performance by maintaining a narrower down track spacing, improving the fraction of the disk accessible in TDMR mode, and increasing the reliability and areal density capacity of the read head.
Implementation Method 1
a dielectric layer is deposited around an outer perimeter of the lower shield
Implementation Method 2
portions of the dielectric layer are then ion milled such that the topography is flattened
Implementation Method 3
a TaOx layer, where x is a numeral, is deposited on the dielectric layer
Implementation Method 4
portions or all of the TaOx layer are then ion milled such that the remaining portions of the TaOx layer the dielectric layer collectively form a substantially planar layer
Data Source
AI summary
The present disclosure generally relates to a dual free layer (DFL) two dimensional magnetic recording (TDMR) read head, and a method of forming thereof. The read head comprises a lower sensor, middle shields disposed on the lower sensor, and an upper sensor disposed on the middle shields. After the lower reader is formed, a dielectric layer is deposited around an outer perimeter of the lower shield. Portions of the dielectric layer are ion milled such that the remaining portions form a substantially flat layer. Another embodiment includes a deposition of a TaOx layer on the dielectric layer, where x is a numeral. Portions of the dielectric layer and the TaOx layer are then ion milled such that the remaining portions of the TaOx layer and the dielectric layer collectively form a substantially planar layer. The middle shields are formed over the lower reader and are substantially planar.