Magnetoresistive Sensor Hard Mask Reduction via Conductor Line Inversion
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Solution Overview
Problem
Conventional magnetoresistive sensors have degraded sensitivity due to the thick hard mask layer required for etching conductor lines, which increases the overall thickness and reduces sensitivity in sensing magnetic field changes.
Innovation Solution
The magnetoresistive sensor design involves forming conductor lines either before or after the magnetoresistive structure, or between them, allowing for a thinner hard mask layer and improved sensitivity by avoiding the need for the hard mask to resist etching of conductor lines, and using semiconductor devices like via-filled or trench-filled conductors to connect the magnetoresistive structure with the conductor lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hard mask layer is made thick to resist etching during conductor line fabrication, then the etching resistance is improved, but the overall thickness increases and sensitivity deteriorates
Solution Approach 1:
The conductor lines are formed prior to the magnetoresistive structure, so the hard mask layer only needs to protect during magnetoresistive layer etching, not conductor line etching. This preliminary action reduces the required hard mask thickness while maintaining sufficient etching resistance for the magnetoresistive layer patterning.
Solution Approach 2:
The conventional sequence is inverted: instead of forming conductor lines after the magnetoresistive structure (requiring thick hard mask), the conductor lines are formed first, then the magnetoresistive structure is deposited and patterned. This reversal eliminates the need for thick hard mask to protect conductor lines during etching.
2Reliability
If the hard mask layer is made thick to protect the magnetoresistive structure during etching, then the protection is improved, but the overall thickness increases and sensitivity deteriorates
Solution Approach 1:
Conductor lines are formed in advance before the magnetoresistive structure is deposited, so the hard mask layer is only required for protecting the magnetoresistive layer during its own etching process, not for protecting conductor lines. This reduces the hard mask thickness requirement while maintaining adequate protection.
Solution Approach 2:
The hard mask layer is positioned specifically where needed - on the magnetoresistive layer during its etching process - rather than being a thick universal protective layer. The conductor lines are already formed in the substrate, so they don't require hard mask protection during subsequent magnetoresistive layer patterning.
3Ease of manufacture
If conductor lines are formed after the magnetoresistive structure, then the fabrication sequence is simplified, but the hard mask layer must be thick to resist etching, degrading sensitivity
Solution Approach 1:
Conductor lines are formed in advance (preliminary action) before the magnetoresistive structure is deposited and processed. This allows the hard mask layer to be thin since it only needs to protect during magnetoresistive layer etching, not during conductor line etching. The fabrication sequence is adjusted to achieve this preliminary formation.
Solution Approach 2:
The conventional sequence of forming magnetoresistive structure then conductor lines is inverted. Conductor lines are formed first in the substrate, then the magnetoresistive structure is deposited and patterned with a thin hard mask. This inversion resolves the contradiction between fabrication ease and sensitivity.
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 design enhances the sensitivity of magnetoresistive sensors by reducing the thickness of the hard mask layer and avoiding metallic pollution and reliability issues caused by temperature and stress changes during the fabrication process, leading to improved performance in sensing external magnetic field changes.
Implementation Method 1
a magnetoresistive sensor with improved sensitivity for sensing a change of external magnetic field
Data Source
AI summary
A magnetoresistive sensor is provided. Specifically, multiple layers of or single layer of conductor line are formed at the same level as an insulating layer on a substrate as a bottom conductive layer. A magnetoresistive structure is formed on the bottom conductive layer and has opposite first surface and second surface. The second surface faces toward the substrate and is contacted with the bottom conductive layer. Afterward, another insulating layer is formed on the first surface, a slot is formed at the same level as the another insulating layer and a conductor line is formed in the slot and contacted with the first surface, so that one layer or multiple layers of conductor line can be formed as a top conductive layer. A lengthwise extending direction of each of the bottom and top conductor layers is intersected a lengthwise extending direction of the magnetoresistive structure with an angle.