Trapezoidal Write Pole Plating Void Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Perpendicular magnetic recording (PMR) technologies face challenges in void defect formation during write pole plating, which leads to corrosion and degraded performance due to poor wettability of the seed layer and the introduction of impurities from excess surfactants.
Innovation Solution
A method involving the deposition of a conformal auxiliary layer on the Ru seed layer, followed by an activation step to remove the auxiliary layer, allowing for electroplating without excess surfactants, thereby minimizing voids and impurities in the write pole layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If excess surfactant is added to improve seed layer wettability, then void formation is reduced, but plated impurities increase and corrosion resistance decreases
Solution Approach 1:
An auxiliary layer is introduced as an intermediary between the seed layer and the plating solution. This auxiliary layer serves as a mediator that improves wettability without requiring excess surfactant in the plating solution, thus preventing both void formation and surfactant-related impurities in the plated write pole layer
Solution Approach 2:
The auxiliary layer is deposited on the seed layer before the plating process begins. This preliminary action prepares the surface with improved wettability characteristics, allowing subsequent plating to proceed without void formation and without needing excess surfactant that would cause impurities
2Ease of operation
If conventional plating process is used with excess surfactant, then wettability is improved, but writer performance degrades due to impurities
Solution Approach 1:
The auxiliary layer acts as an intermediary that provides the necessary wettability improvement without introducing surfactant-related impurities into the plated write pole layer, thereby maintaining writer performance while achieving ease of plating operation
3Manufacturing precision
If surfactant is used to improve wettability, then plating fills narrow openings better, but corrosion resistance decreases
Solution Approach 1:
The auxiliary layer serves as a mediator that enables complete filling of narrow openings during plating without requiring surfactant, thus achieving manufacturing precision while avoiding the introduction of corrosive impurities into the plated structure
Solution Approach 2:
The harmful surfactant component is extracted from the plating process entirely. Instead of relying on surfactant to achieve good plating fill quality, the process uses the auxiliary layer to provide the necessary surface properties, removing the source of corrosion susceptibility
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 reduces void defects and impurities, enhancing write pole performance and wafer yields while avoiding the use of excess surfactants, thus improving the reliability and efficiency of PMR writer fabrication.
Implementation Method 1
a first auxiliary layer is deposited on the seed layer
Implementation Method 2
an activation step to remove the auxiliary layer, allowing for electroplating
Implementation Method 3
electroplating without excess surfactants, thereby minimizing voids and impurities in the write pole layer
Data Source
AI summary
A method of forming a write pole in a PMR head is disclosed that involves forming an opening in a mold forming layer. A conformal Ru seed layer is formed within the opening and on a top surface. An auxiliary layer made of CoFeNi or alloys thereof is formed as a conformal layer on the seed layer. All or part of the auxiliary layer is removed in an electroplating solution by applying a (−) current or voltage during an activation step that is controlled by activation time. Thereafter, a magnetic material is electroplated with a (+) current to fill the opening and preferably has the same CoFeNi composition as the auxiliary layer. The method avoids Ru oxidation that causes poor adhesion to CoFeNi, and elevated surfactant levels that lead to write pole impurities. Voids in the plated material are significantly reduced by forming a seed layer surface with improved wettability.