Integrated AMR Sensor with Dielectric Capping Layer
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Solution Overview
Problem
Conventional magnetoresistive devices face issues with current shunting through metal capping layers, leading to degraded performance and increased complexity in the process flow, which affects the accuracy and reliability of magnetic field sensing.
Innovation Solution
The integration of a patterned Anisotropic Magneto Resistive (AMR) stack with a dielectric capping layer (e.g., AlN) and a thin seed layer (e.g., TaN) underneath the AMR material layer, eliminating the need for additional routing layers and reducing noise sources by minimizing metal-metal interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal capping layer is used to cap the AMR stack, then the AMR stack is protected from environmental degradation, but current shunting occurs through the metal capping layer leading to degraded sensor performance
Solution Approach 1:
The patent changes the electrical parameter (conductivity) of the capping layer from metallic (conductive) to dielectric (insulating). The dielectric capping layer maintains protective functions while eliminating the harmful current shunting effect that occurs with metal capping layers, thus resolving the contradiction between protection and measurement precision.
Solution Approach 2:
The patent introduces a dielectric material as an intermediary between the AMR stack and the external environment. This dielectric capping layer serves as a mediator that provides environmental protection while blocking current shunt paths, allowing the AMR effect to be measured accurately without the harmful effects of metal capping.
2Reliability
If additional routing layers are added to prevent current shunting, then current shunting is eliminated, but the process flow complexity increases
Solution Approach 1:
The patent extracts the capping layer function from the metal interconnect stack and implements it as a separate dielectric layer. This eliminates the need for additional metal routing layers to prevent current shunting, as the dielectric capping layer inherently blocks current flow while maintaining protection functions, thus reducing process complexity.
3Ease of operation
If metal-metal interfaces are increased to provide additional current paths, then connectivity is improved, but noise sources increase affecting measurement accuracy
Solution Approach 1:
The patent changes the material parameter of the capping layer from conductive metal to insulating dielectric. This eliminates current shunting through the capping layer and reduces noise from metal-metal interfaces, while connectivity is maintained through properly designed contact holes and bonding structures that provide controlled current paths only where needed.
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 configuration enhances the performance of AMR sensors by preventing current shunting and reducing noise, while maintaining the simplicity of existing semiconductor process flows, thereby improving the accuracy and reliability of magnetic field sensing.
Implementation Method 1
AMR sensors include a material in which there is a dependence of its electrical resistance on the angle between the direction of electric current and the direction of magnetization observed. AMR sensors offer robust non-contact measurement of changes in the magnetic field as seen by the sensor
Implementation Method 2
The integration of a patterned Anisotropic Magneto Resistive (AMR) stack with a dielectric capping layer (e.g., AlN) and a thin seed layer (e.g., TaN) underneath the AMR material layer, eliminating the need for additional routing layers and reducing noise sources by minimizing metal-metal interfaces
Data Source
AI summary
An integrated device includes a substrate having a semiconductor surface layer including functional circuitry, a lower metal stack on the semiconductor surface layer, an interlevel dielectric (ILD) layer on the lower metal stack, a top metal layer providing AMR contact pads and bond pads coupled to the AMR contact pads in the ILD layer. An AMR device is above the lower metal stack lateral to the functional circuitry including a patterned AMR stack including a seed layer, an AMR material layer, and a capping layer, wherein the seed layer is coupled to the AMR contact pads by a coupling structure. A protective overcoat (PO layer) is over the AMR stack. There are openings in the PO layer exposing the bond pads.