Magnetoresistive Element Ta-Ti Insulating Layer Etching Control
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Solution Overview
Problem
Manufacturing magnetoresistive elements with uniform etching rates across large wafers is challenging, leading to deteriorated characteristics due to insufficient or excessive etching of the free layer, which affects the magnetoresistive element's performance.
Innovation Solution
Incorporating a Ta-containing or Ti-containing insulating layer with specific volume ratios between the magnetic layers to control the etching rate and improve the selection ratio of the insulating layer, thereby preventing penetration and maintaining element characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma etching is used to process the free layer, then productivity is improved through uniform etching of large diameter substrates, but manufacturing precision deteriorates due to non-uniform etching rates across the wafer surface
Solution Approach 1:
The patent applies local quality by modifying the insulating layer composition locally at the interface with the free layer. Specifically, the insulating layer is designed with a gradient structure where the proportion of Ta or Ti increases toward the free layer interface, creating localized etching resistance exactly where needed to prevent penetration, while maintaining overall plasma etching uniformity across the wafer surface.
2Device complexity
If the insulating layer is made thinner to reduce device complexity, then device complexity is reduced, but reliability deteriorates due to increased risk of etching penetration through the insulating layer
Solution Approach 1:
The patent applies composite materials by creating an insulating layer with composite composition - a gradient structure combining MgO (or AlO) with Ta or Ti elements. The insulating layer contains regions with different compositions: the portion closer to the free layer has higher Ta/Ti content providing etching resistance, while other regions maintain lower Ta/Ti content. This composite structure achieves both thinness and high etching resistance simultaneously.
3Productivity
If the etching rate is increased to improve manufacturing speed, then productivity is improved, but manufacturing precision deteriorates due to excessive etching that penetrates the insulating layer
Solution Approach 1:
The patent applies preliminary action by pre-configuring the insulating layer with a gradient composition structure before the etching process. The Ta/Ti-enriched region is formed in advance at the interface with the free layer, creating a protective barrier that prevents etching penetration even when high etching rates are used to improve manufacturing speed. This preliminary structural preparation enables aggressive etching without compromising precision.
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
Achieves a high selection ratio of the insulating layer to the free layer, ensuring consistent and improved magnetoresistive element performance across the entire wafer surface, meeting the requirements for high MR ratio and preventing characteristic deterioration.
Implementation Method 1
processing the first magnetic layer by plasma etching
Implementation Method 2
irradiate ions or radicals generated in the plasma to a substrate
Implementation Method 3
improve the selection ratio of the insulating layer, thereby preventing penetration
Data Source
AI summary
The present invention provides a method for manufacturing a magnetoresistive element having a high selection ratio of an insulating layer to a free layer. The method for manufacturing a magnetoresistive element includes the steps of preparing (left drawing, middle drawing) a substrate on which a free layer, a fixed layer disposed under a first magnetic layer, and a barrier layer that is an insulating layer disposed between the free layer and the fixed layer are formed and processing (right drawing) the free layer by plasma etching, in which an insulating layer configuring the barrier layer contains a Ta element or a Ti element.