Silicon Diffusion Contact Pad for Write Pole Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In magnetic recording hard disk drives, the precise calibration of thermal fly-height control (TFC) heaters for maintaining optimal head-disk spacing is challenging due to the difficulty in aligning photoresist masks for patterning contact pads, which can result in spacing loss between the write pole and the recording layer, and potential damage during touchdown.
Innovation Solution
A contact pad with a silicon layer surrounding the write pole end is used, where silicon diffuses into the ferromagnetic material to reduce the magnetic moment and create a recessed portion protected by a diamond-like carbon overcoat, allowing for a wider contact pad that minimizes wear during touchdown without covering the write pole end.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a contact pad is patterned on the slider's disk-facing surface to protect the write pole during touchdown, then the write pole is protected from damage, but the alignment of photoresist masks becomes difficult due to very small dimensions, resulting in manufacturing complexity and potential spacing loss
Solution Approach 1:
A silicon layer is deposited as an intermediary material that surrounds the write pole end. This silicon layer serves as a mediator between the contact pad and the write pole, allowing the contact pad to be wider for better protection while the silicon layer prevents direct contact and spacing loss issues. The silicon layer is subsequently removed through diffusion into the write pole material, leaving a protected write pole end.
Solution Approach 2:
The silicon layer is deposited beforehand to surround the write pole end before the contact pad is fully formed. This preliminary action allows the contact pad to be patterned with wider dimensions for better protection coverage, while the pre-positioned silicon layer ensures proper spacing and alignment is maintained during the subsequent processing steps.
2Reliability
If additional protective layers are added to cover the write pole, then the write pole is protected during touchdown, but spacing loss occurs between the write pole and the recording layer on the disk
Solution Approach 1:
Instead of adding protective layers across the entire write pole structure, the silicon layer is applied locally only around the write pole end where protection is needed during touchdown. This localized approach provides protection exactly where required while maintaining the original spacing between the write pole and the recording layer in the critical data writing region.
Solution Approach 2:
The silicon layer surrounding the write pole end is extracted or removed through diffusion into the write pole material. This extraction process eliminates the additional protective layer that would cause spacing loss, while the diffused silicon remains embedded in the write pole end to provide the necessary protection during touchdown events.
3Duration of action of stationary object
If the contact pad is made wider to minimize wear during touchdown, then durability is improved, but alignment with the write pole becomes more difficult, increasing manufacturing complexity
Solution Approach 1:
The silicon layer acts as an intermediary that decouples the alignment requirements between the contact pad and the write pole. By depositing silicon that surrounds the write pole end first, the contact pad can then be patterned with wider dimensions for improved durability without requiring precise alignment with the write pole, as the silicon layer provides the necessary spacing and positioning reference.
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 solution effectively protects the write pole during touchdown by reducing the magnetic moment and allowing for a wider contact pad that minimizes wear, while avoiding the challenges of precise photoresist alignment and spacing loss, thus ensuring reliable head-disk contact.
Implementation Method 1
silicon diffuses into the ferromagnetic material to reduce the magnetic moment
Implementation Method 2
protected by a diamond-like carbon overcoat
Implementation Method 3
When current is applied to the heater, the heater expands and causes the write head's write pole to expand and thus move closer to the disk surface
Data Source
AI summary
A magnetic recording disk drive head carrier or slider has a contact pad that protects the disk drive's write pole during touchdown of the slider with the disk. The contact pad is located in a window region of the slider's disk-facing surface that includes the write pole end. The contact pad includes a layer of silicon that surrounds the write pole end but does not cover it. The silicon does not cover the write pole end because it has diffused into the ferromagnetic material of the write pole end. This removes the silicon over the write pole end. The contact pad includes a protective overcoat on the silicon-containing write pole end and surrounding silicon layer. The protective overcoat thus has a recess over the write pole due to the absence of silicon, so that the protective overcoat surrounding the recess provides protection to the recessed write pole end during touchdown.