Side Shield Formation Using Sacrificial Layer to Prevent Over-Milling
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Solution Overview
Problem
Current writer fabrication processes result in over-milling into side shields, leading to a cross-track slope and reduced side shield volume, which contributes to side track erasure (STE) hot spots in magnetic recording heads.
Innovation Solution
A method involving the formation of a patterned sacrificial layer on top of the side shields, followed by a trailing surface bevel process that minimizes over-milling into the side shields, ensuring substantially flat upper surfaces and maintaining side shield volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a trailing surface bevel process is applied to the write pole layer, then the write pole trailing surface is properly formed, but the side shield volume is reduced due to over-milling
Solution Approach 1:
A sacrificial layer is deposited on the side shield layers before the trailing surface bevel process. This preliminary action protects the side shields during subsequent milling operations, preventing over-milling and volume loss while allowing proper formation of the write pole trailing surface.
Solution Approach 2:
The sacrificial layer acts as an intermediary protective element between the milling tool and the side shield layers. It absorbs the mechanical impact of the bevel process, enabling precise write pole formation without directly damaging the side shields.
2Reliability
If side shield layers are formed proximate to the write pole layer, then side track erasure is reduced, but the fabrication process complexity increases
Solution Approach 1:
The fabrication process is segmented into distinct stages: side shield formation, sacrificial layer deposition, and trailing surface beveling. This segmentation allows each operation to be optimized independently, managing overall process complexity while achieving reliable side track erasure prevention.
Solution Approach 2:
The sacrificial layer serves as a temporary intermediary structure that simplifies the fabrication process. It enables the trailing surface bevel to be performed without directly exposing the side shields to milling, reducing process complexity compared to attempting to protect side shields through complex masking or selective etching methods.
3Manufacturing precision
If the side shield trailing surfaces are made flush with the write pole trailing surface, then the bearing surface is planarized, but side track erasure hot spots occur due to reduced side shield volume
Solution Approach 1:
The sacrificial layer is deposited before the trailing surface bevel process, creating a preliminary protective structure. This allows the side shield trailing surfaces to be formed flush with the write pole while preserving side shield volume, preventing erasure hot spots while maintaining bearing surface planarity.
Solution Approach 2:
The sacrificial layer, which adds an extra fabrication step, ultimately benefits the device by preventing side track erasure. The apparent complexity of depositing and later removing the sacrificial layer converts into a benefit by preserving critical side shield volume and eliminating erasure hot spots.
Data Source
AI summary
A method includes forming a write pole layer having a front surface, a leading surface, a trailing surface and side surfaces connecting the leading surface to the trailing surface. The method also includes forming side shield layers proximate to the side surfaces of the write pole layer. A patterned sacrificial layer is deposited over the side shield layers, and a trailing surface bevel is formed on the write pole layer.