CMP Stop Layer for Linear Back Edge in SAF Read Heads
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Solution Overview
Problem
In semiconductor manufacturing, particularly for devices using magnetic materials, small topological structures left from processing can impact the magnetic properties of the read head, such as in disc drives, making it challenging to achieve a substantially linear back edge in the reader stack.
Innovation Solution
The process involves depositing a backfill layer, a chemical-mechanical-polishing stop layer, and a sacrificial layer to facilitate the removal of topographical remnants during the fabrication of a long SAF read head, ensuring a substantially linear back edge by controlling the CMP process rates of these layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional fabrication methods are used to create the reader stack, then the manufacturing process is simpler, but topological remnants are left behind that impact magnetic properties
Solution Approach 1:
The patent applies preliminary action by depositing the CMP stop layer and sacrificial layer before the final read head structure is complete. These layers are prepared in advance to enable subsequent removal of topological remnants through CMP processing, thereby ensuring magnetic properties are not compromised while managing fabrication complexity
Solution Approach 2:
The CMP stop layer and sacrificial layer serve as intermediary elements that facilitate the removal of topological remnants. These intermediary layers enable the CMP process to selectively remove unwanted material without damaging the reader stack, thus protecting magnetic properties while adding controlled complexity to the fabrication process
2Manufacturing precision
If a substantial linear back edge is achieved through traditional methods, then the magnetic properties are maintained, but it is difficult to remove topological remnants
Solution Approach 1:
The patent segments the removal process by introducing distinct layers (CMP stop layer and sacrificial layer) that enable selective removal of topological remnants. This segmentation allows the CMP process to target specific areas with precision while maintaining the linear back edge geometry, thereby achieving both manufacturing precision and ease of manufacture
Solution Approach 2:
The patent utilizes parameter changes in the CMP process by controlling the polishing rates of different layers. The CMP stop layer and sacrificial layer have different polishing rates that enable precise control over the removal of topological remnants while preserving the linear back edge, thus achieving both precision and ease of manufacture
3Manufacturing precision
If multiple layers are deposited to facilitate CMP processing, then topological remnants are effectively removed, but the device structure becomes more complex
Solution Approach 1:
The patent extracts the topological remnants from the final device structure by using the CMP stop layer and sacrificial layer as temporary structures. These layers are deposited, used to facilitate removal of unwanted material, and then removed themselves, leaving only the desired linear back edge and reader stack structure. This extraction approach achieves high manufacturing precision while minimizing the permanent complexity of the device structure
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 effectively removes topological remnants, ensuring the magnetic properties of the read head are not compromised and achieving a substantially linear back edge, which is difficult to achieve with traditional methods.
Implementation Method 1
chemical-mechanical-polishing stop layer, sacrificial layer disposed on top of the chemical-mechanical-polishing stop layer
Data Source
AI summary
In accordance with certain embodiments, a method can be utilized that includes depositing a backfill material layer over a reader stack; depositing a chemical-mechanical-polishing stop layer above the layer of backfill material; and depositing a sacrificial layer on top of the chemical-mechanical-polishing stop layer.