TMR Top Contact Formation With Low-Temperature Capping Layers

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Solution Overview

Problem

Current methods for fabricating electroconductive contacts on tunneling magnetoresistance (TMR) elements are limited by high temperature processes that can damage the elements and require complex multi-step photolithography processes, making it challenging to achieve reliable and efficient contact formation, especially for small diameter TMR elements.

Innovation Solution

A method involving the deposition of a capping layer, an insulator, and a conducting material like titanium nitride on the TMR elements, using photolithography to expose and etch specific areas, and forming electroconductive contacts while protecting the TMR elements from high temperature exposure, simplifying the process and ensuring reliable contact formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional methods are used to form electroconductive contacts on TMR elements, then electrical connectivity is achieved, but the TMR elements are damaged due to high temperature processes

Engineering Contradiction:

Improveelectrical connectivityVSAvoidtemperature damage to TMR elements

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A capping layer is deposited on the TMR element before forming the electroconductive contact. This preliminary protective action allows subsequent low-temperature processing to occur without damaging the TMR element, as the capping layer shields it from thermal and chemical harm during the contact formation process

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs low-temperature deposition processes (such as sputtering or chemical vapor deposition at reduced temperatures) to form the electroconductive contact and capping layer. By changing the temperature parameter from conventional high-temperature processes to low-temperature processes, the TMR element is protected from thermal damage while still achieving reliable electrical connectivity

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If photolithography and etching are used to form electroconductive contacts, then manufacturing precision is improved, but process complexity increases

Engineering Contradiction:

Improvecontact formation precisionVSAvoidfabrication process steps

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The fabrication process is segmented into distinct functional steps: depositing the capping layer, depositing the insulator, photolithography patterning, etching, and finally depositing the electroconductive contact material. This segmentation allows each step to be optimized independently, achieving precise contact formation while managing overall process complexity through systematic breakdown of the fabrication sequence

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An insulator layer is introduced as an intermediary between the capping layer and the electroconductive contact. This intermediary layer facilitates precise pattern transfer and protects underlying structures during etching, enabling manufacturing precision while the insulator itself serves as a manageable intermediate step in the overall process

Inventive Principle:

Principle #24Intermediary (Mediator)

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 allows for the formation of reliable electroconductive contacts on TMR elements without damaging them, even for elements with diameters less than one micron, by using lower temperature processes and simplifying the fabrication steps, thereby enhancing the efficiency and reliability of the contact formation process.

Implementation Method 1

patterning the first photoresist using photolithography to expose portions of the insulator

Methodology Applied

Scientific EffectPhotolithography: Photopolymerisation

Implementation Method 2

depositing a capping layer on a semiconductor device structure

Methodology Applied

Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Implementation Method 3

depositing an insulator on the capping layer

Methodology Applied

Scientific EffectChemical Vapour Deposition: Chemical Vapour Deposition

Data Source

PatentUS20230413679A1Fabricating an electroconductive contact on a top surface of a tunneling magnetoresistance element

Publication Date: 2023.12.21 ALLEGRO MICROSYSTEMS LLC

AI summary

In one aspect, a method includes depositing a capping layer on a semiconductor device structure. The semiconductor device includes a plurality of tunneling magnetoresistance (TMR) elements, a corresponding one hard mask on each TMR element, a metal layer, and a plurality of electroconductive vias directing connecting the TMR elements to the metal layer. The method further includes depositing an insulator on the capping layer, depositing a first photoresist on the insulator, patterning the first photoresist using photolithography to expose portions of the insulator, etching the exposed portions of the insulator and the hard masks to expose top surfaces of the TMR elements, stripping the first photoresist, and depositing a conducting material on the top surfaces of the TMR elements to form an electroconductive contact.