Magnetic Tunnel Junction Integration Without Patterning
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Solution Overview
Problem
Conventional methods for integrating magnetic tunnel junctions (MTJs) into integrated circuits require expensive photolithography and etching processes, leading to thick hardmask stacks that exceed the height limits of advanced via stacks, limiting miniaturization and increasing costs.
Innovation Solution
A method for fabricating integrated circuits with MTJs without a patterning process, involving the deposition of a first diffusion barrier layer, forming trenches, and depositing electrodes and MTJs according to the electrode shape, allowing for a thinner MTJ stack and increased density without the need for expensive photolithography and etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography and etching processes are used for MTJ integration, then MTJ patterning is achieved, but the hardmask stack thickness exceeds via stack height limits and costs increase
Solution Approach 1:
The patent extracts and eliminates the photolithography and etching patterning steps from the MTJ fabrication process. Instead of using conventional hardmask-based patterning, the method directly deposits MTJ materials in the desired pattern, removing the source of excessive stack thickness and associated costs while maintaining patterning precision
Solution Approach 2:
The patent performs preliminary patterning of the bottom electrode layer before MTJ deposition. This preliminary structured layer serves as a self-aligned mask and template, enabling subsequent MTJ materials to be deposited only in the desired locations without requiring additional patterning steps or thick hardmask stacks
2Manufacturing precision
If conventional patterning processes are used, then MTJ structures are formed, but miniaturization is limited due to process constraints
Solution Approach 1:
The patent changes the fundamental deposition parameters and material states during MTJ fabrication. By using atomic layer deposition (ALD) and controlling deposition conditions, the process achieves precise control over MTJ dimensions at the nanoscale, enabling miniaturization to dimensions (pitch < 50 nm, diameter < 35 nm) that are limited by conventional photolithography resolution
3Manufacturing precision
If photolithography and etching are used for MTJ integration, then patterning is achieved, but fabrication costs increase
Solution Approach 1:
The patent merges multiple separate fabrication steps into a single integrated deposition process. By combining the patterning function and MTJ formation into one continuous deposition sequence using self-aligned layers, the process eliminates the need for separate photolithography, hardmask deposition, and etching steps, thereby reducing fabrication costs while maintaining patterning precision
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
Enables MTJ stack thicknesses less than 40 nm, pitches less than 50 nm, and diameters less than 35 nm, facilitating miniaturization and increased density, while eliminating the need for costly patterning processes and fitting within tighter integration constraints.
Implementation Method 1
depositing a first diffusion barrier layer above an oxide layer having a conductive pillar therein
Implementation Method 2
depositing a first electrode in the first trench
Data Source
AI summary
Certain aspects of the present disclosure provide techniques for fabricating an integrated circuit with a magnetic tunnel junction (MTJ) without a patterning process for the MTJ. An example method generally includes depositing a first diffusion barrier layer above an oxide layer having a conductive pillar therein, forming a first trench in the first diffusion barrier layer above the conductive pillar, depositing a first electrode in the first trench such that the first electrode is coupled to the conductive pillar, removing the oxide layer and the first diffusion barrier layer to expose the conductive pillar and the first electrode, and depositing an MTJ above the first electrode according to a shape of the first electrode.