TMR Layer Stack Two-Stage Etching Process
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Solution Overview
Problem
The production of TMR components faces challenges in miniaturization and electrical contacting, limiting their cost-effective manufacturing in large quantities, especially when integrated with other electronic components on a semiconductor chip.
Innovation Solution
A two-stage etching process is employed to structure the TMR layer stack, where the first ferromagnetic layer is carefully etched to expose the insulating layer, and then the insulating and second ferromagnetic layers are etched with strong ion bombardment, protected by a thin layer, allowing for efficient and rapid production of TMR components with simplified contacting using a semiconductor chip substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single-step etching process is used to remove the entire TMR layer stack, then the production time is reduced, but the sensitive layer transition is damaged due to excessive ion bombardment
Solution Approach 1:
The etching process is divided into two sequential steps: first etching the ferromagnetic layer to expose the insulating layer, then etching the insulating layer to expose the substrate. This segmentation allows controlled ion bombardment at each stage, preventing damage to sensitive interfaces while maintaining production efficiency.
Solution Approach 2:
The first etching step performs a preliminary action by removing the ferromagnetic layer and exposing the insulating layer before the second etching step. This preliminary exposure enables the subsequent etching of the insulating layer with controlled ion bombardment, preventing direct damage to the ferromagnetic-insulating interface.
2Productivity
If the TMR layer stack is etched with strong ion bombardment, then the etching speed increases, but the sensitive layer transition is stressed and damaged
Solution Approach 1:
The etching process is segmented into two steps with different ion bombardment intensities. The first step uses milder conditions to protect the ferromagnetic-insulating interface, while the second step uses stronger ion bombardment to rapidly remove the insulating layer, optimizing both speed and quality.
Solution Approach 2:
Different etching conditions are applied to different stages of the process. The first etching step uses parameters optimized for protecting sensitive interfaces, while the second step uses parameters optimized for rapid material removal, achieving local optimization of both precision and speed.
3Ease of manufacture
If the TMR component is produced separately from other electronic components, then the production process is simpler, but the packing density and electrical connection efficiency are reduced
Solution Approach 1:
The TMR component production is merged with the semiconductor chip fabrication process. The TMR layer stack is deposited and etched on the same substrate as other electronic components, allowing simultaneous production and high-density integration without complicating the overall manufacturing process.
Solution Approach 2:
The substrate serves multiple functions: it acts as the base for the TMR layer stack, provides the structural foundation for other electronic components, and enables integrated electrical connections. This multi-functionality increases packing density while maintaining manufacturing simplicity.
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 method enables the cost-effective production of TMR components in large quantities while ensuring the sensitive layer transitions are protected, facilitating high packing density and efficient electrical connections with other components on a semiconductor chip.
Implementation Method 1
Magnetic tunnel resistance (TMR) is a magneto-resistive effect that occurs in magnetic tunnel junctions (MTJ). Devices that make use of the magnetic tunneling resistance effect are referred to as TMR devices.
Implementation Method 2
Etching requires a very careful approach in order not to burden the sensitive layer transition with excessive ion bombardment
Data Source
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AI summary
The inventive manufacturing process for TMR devices is characterized by a two-stage etching process in which the individual layers of the TMR layer stack are structured in two successive steps. First, the TMR layer stack B is deposited onto a substrate A. The TMR layer stack B has a first and second ferromagnetic layer B1, B2, which are separated by an insulating layer B3. A contact layer B5 is located on the first ferromagnetic layer B1. In the first step of the two-stage etching process, only the first ferromagnetic layer B1 of the layer stack B is etched until the insulating layer B3 is exposed, while in the second step the insulating layer B3 and the second ferromagnetic layer B2 are etched, thus protecting the sensitive layer interface.An advantage of the inventive method is that in the first step, which requires a very careful approach to avoid stressing the sensitive layer interface with excessive ion bombardment, only a relatively thin layer of the TMR layer stack needs to be removed. In the second step, however, the sensitive layer interface is protected, so that etching with a relatively strong ion bombardment can be carried out without the risk of stressing the layer interface.