Magnetic Tunnel Junction Side Wall Protection via Insulating Film
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Solution Overview
Problem
Magnetic memory cells with a partial coverage structure of the upper magnetic layer over the tunnel barrier layer suffer from short-circuits due to metal substances attaching to the side walls during etching, leading to leakage paths and reliability issues in magnetic random access memory (MRAM) devices.
Innovation Solution
A semiconductor device design featuring a data recording layer, a tunnel barrier layer, a data reference layer, and a cap layer, where the data reference layer and cap layer are processed to overlap with the same shape, and a first insulating film covers the side walls of these layers, preventing metal substances from attaching to the tunnel barrier layer and thus avoiding short-circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the upper magnetic layer is processed by etching to achieve partial coverage over the tunnel barrier layer, then the magnetic memory cell structure is formed, but metal substances attach to the side wall of the processed tunnel barrier layer causing short-circuit
Solution Approach 1:
A capping layer is introduced as an intermediary component between the upper magnetic layer and the tunnel barrier layer. This capping layer covers the side wall of the tunnel barrier layer, preventing metal substances from the upper magnetic layer from attaching to the tunnel barrier layer side wall during etching, thereby eliminating the short-circuit path while maintaining the partial coverage structure.
2Ease of manufacture
If the upper magnetic layer covers the tunnel barrier layer partially, then the magnetic memory cell is formed, but leakage paths are created due to metal substance attachment
Solution Approach 1:
The capping layer serves as a protective intermediary that is deposited after the upper magnetic layer pattern formation. It specifically covers the exposed side wall of the tunnel barrier layer, preventing metal substances from creating leakage paths between the upper magnetic layer and tunnel barrier layer, thus maintaining device reliability.
3Productivity
If metal substances attach to the tunnel barrier layer side wall during etching, then the etching process is completed, but short-circuit and reliability deterioration occur
Solution Approach 1:
The capping layer is deposited as a preliminary protective action immediately after the upper magnetic layer pattern formation and before any subsequent processing that might cause metal attachment. This preliminary capping prevents metal substances from attaching to the tunnel barrier layer side wall during and after the etching process, ensuring device reliability is maintained.
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
The solution effectively inhibits short-circuits in magnetic tunnel junctions, enhancing the reliability of magnetic memory cells by ensuring that metal substances do not attach to the tunnel barrier layer's side walls, thereby maintaining normal data recording functionality.
Implementation Method 1
a first insulating film lies in contact with the respective side walls of the data reference layer and the cap layer, while no first insulating film lies on the respective side walls of the data recording layer and the tunnel barrier layer
Implementation Method 2
a magnetoresistance effect element is used as a magnetic memory cell. A typical magnetoresistance effect element is equipped with a magnetic tunnel junction (MTJ)
Data Source
AI summary
An object is to prevent a short failure in magnetic tunnel junction and thereby suppress a semiconductor device having a magnetic memory cell from having deteriorated reliability. First, a data reference layer and a cap layer are patterned. After formation of an oxygen-free first insulating film on their side walls, a base layer, a data recording layer, and a tunnel barrier layer are patterned. During patterning of the base layer, data recording layer, and tunnel barrier layer, adhesion of a metal substance of the data reference layer and the cap layer to the side wall of the tunnel barrier layer can be prevented because the data reference layer and the cap layer are covered by the first insulating film.