PMR Write Pole with Segmented Trapezoidal-Rectangular Cross Section
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Solution Overview
Problem
Manufacturing trapezoidal write poles with beveled tips for perpendicular magnetic recording (PMR) hard drives often results in undesirable variations in track width due to the bevel affecting the write pole parameters.
Innovation Solution
A write pole design featuring a lower trapezoidal region and an upper rectangular region, where the beveled surface intersects the air bearing surface, maintaining a constant track width regardless of bevel position, achieved through a damascene trench formation method with specific cross-sectional shapes and materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a beveled surface is added to a trapezoidal write pole to achieve a thin pole tip, then the pole tip thickness is reduced, but the track width becomes variable and manufacturing precision deteriorates
Solution Approach 1:
The write pole is divided into two distinct regions: a lower trapezoidal region and an upper rectangular region. This segmentation allows the beveled surface to be positioned in the rectangular region where it can reduce pole tip thickness without affecting the track width defined by the trapezoidal region's parallel sides.
Solution Approach 2:
Different regions of the write pole are given different cross-sectional shapes tailored to their specific functions. The lower trapezoidal region maintains constant track width for precise positioning, while the upper rectangular region allows beveling for thin pole tip creation. Each region's geometry is optimized for its particular role in the overall pole function.
2Shape
If a beveled surface is positioned to reduce pole tip thickness, then the pole tip becomes thinner, but manufacturing complexity increases due to precise positioning requirements
Solution Approach 1:
By segmenting the pole into trapezoidal and rectangular regions, the bevel positioning problem is relocated to the rectangular region where the geometry naturally constrains the bevel position. The parallel sides of the trapezoidal region define the track width, making the bevel position in the upper region less critical for dimensional control.
Solution Approach 2:
The cross-sectional geometry parameters change from uniform trapezoidal shape to a composite shape with trapezoidal lower region and rectangular upper region. This parameter change allows the bevel angle and position to be adjusted independently without compromising track width, as the rectangular region provides a stable geometric reference.
3Ease of manufacture
If a uniform trapezoidal cross-section is used throughout the write pole, then manufacturing is simpler, but the pole cannot maintain both constant track width and thin pole tip simultaneously
Solution Approach 1:
The write pole is segmented into two regions with different cross-sectional geometries. The lower trapezoidal region maintains ease of manufacture with standard damascene trench formation, while the upper rectangular region enables thin pole tip creation through controlled beveling. This segmentation achieves dual geometry capability without requiring complex manufacturing processes.
Solution Approach 2:
The solution moves from a two-dimensional uniform trapezoidal cross-section to a three-dimensional composite structure with varying cross-sections along the pole length. The transition from trapezoidal to rectangular cross-section occurs at a specific height, enabling different functional requirements to be met in different vertical zones of the pole.
Data Source
AI summary
A method of forming a magnetic recording head is provided. The method comprises the steps of forming a damascene trench comprising a lower region having a substantially trapezoidal cross-section and an upper region having a substantially rectangular cross-section, and providing a magnetic material within the damascene trench.