Magnetic Sensing Element RIE Stop Layer Etch Control
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Solution Overview
Problem
The existing process for producing tunneling magnetic sensing elements results in a large step height and variation in distance between shield layers, leading to suboptimal read characteristics due to the etching process and shadow effects during film formation.
Innovation Solution
A magnetic sensing element with a laminate structure including a pinned magnetic layer, a nonmagnetic material layer, and first and second reactive-ion-etching (RIE) stop layers, where the RIE stop layers function as etching stops and are composed of materials like Cr, Pt, Ir, Ru, Rh, Pd, and Ag, reducing etch rates and step heights, and a process involving specific layer formation and etching steps to minimize variations in shield layer distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If ion milling is used to remove layers during production, then the laminate shape can be formed, but large step height and variation in distance between shield layers occur
Solution Approach 1:
The patent changes the etching parameter from ion milling to reactive ion etching (RIE), which provides better etching control and reduces step height. By adjusting the etching method parameters, the distance variation between shield layers is reduced while still achieving the required laminate shape formation.
Solution Approach 2:
The patent introduces a reactive ion etching process as an intermediary step between layer formation and final structure completion. This intermediate etching process uses reactive ions to selectively remove material with precise control, reducing the step height caused by direct ion milling while maintaining the necessary laminate geometry.
2Ease of manufacture
If shadow effects occur during film formation, then certain areas are protected from deposition, but large variation in distance between shield layers results
Solution Approach 1:
The patent applies partial shadow effects selectively during film formation, using the shadow effect only in specific areas where protection is needed rather than allowing it to occur universally. This controlled partial application reduces the variation in shield layer distance while maintaining the manufacturing simplicity of using shadow effects for selective area protection.
3Manufacturing precision
If RIE stop layers are used to reduce etch rates, then step height is reduced, but manufacturing process complexity increases
Solution Approach 1:
The patent designs the RIE stop layers to serve multiple functions: they act as etching stop layers to control step height, and simultaneously serve as part of the final functional structure of the magnetic sensing element. This multi-functionality reduces the need for additional separate layers, thereby limiting the increase in manufacturing process complexity while achieving step height reduction.
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
The solution effectively reduces the variation in height and distance between shield layers, improving read characteristics and enabling the production of magnetic sensing elements with enhanced performance.
Implementation Method 1
first and second reactive-ion-etching (RIE) stop layers... reducing etch rates and step heights
Data Source
AI summary
A magnetic sensing element including a laminate and a bias layer is provided. A first reactive-ion-etching (RIE) stop layer is disposed on a free magnetic layer. Second RIE stop layers are disposed on bias layers. The first and second RIE stop layers function as stop layers when layers on the first and second RIE stop layers are removed by reactive ion etching in a production process. Reactive ion etching is completed when the first RIE stop layer and the second RIE stop layers are exposed, the first and second RIE stop layers being disposed at almost the same height. Also provided is a process for producing the magnetic sensing element.