Pyramidal MTJ Structure Without Ion Beam Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current magnetic tunnel junction (MTJ) structure patterning processes, particularly in MRAM technology, face challenges such as physical damage from ion beam etching, corner erosion of top electrodes, and reduced memory density due to taller top electrodes, which increase the risk of shorting and limit alignment accuracy.
Innovation Solution
A memory structure is developed without using ion beam etching, featuring a pyramidal MTJ structure with a top electrode having a seam, where the MTJ structure and top electrode are formed using a bilayer dielectric material mask and physical vapor deposition, ensuring no corner erosion and maintaining a constant critical dimension, thus preventing shorting and enhancing alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion beam etching is used for MTJ structure patterning, then manufacturing precision is improved, but physical damage to the MTJ structure and corner erosion of the top electrode occur
Solution Approach 1:
The patent removes the ion beam etching step from the MTJ structure patterning process entirely. Instead, it uses a self-aligned deposition approach where the top electrode serves as a mask during MTJ formation, eliminating the harmful ion beam etching process while maintaining patterning precision through the natural alignment of deposited layers.
Solution Approach 2:
The patent inverts the conventional patterning sequence by first depositing the top electrode and then using it as a mask for MTJ structure formation. This reverse approach eliminates the need for separate etching steps and prevents corner erosion by avoiding ion beam exposure of the top electrode corners.
2Reliability
If top electrode height is increased to prevent shorting, then reliability is improved, but memory density is reduced due to increased cell area
Solution Approach 1:
The patent transitions from controlling shorting prevention through vertical dimension (height) to controlling it through lateral dimension (pyramidal shape). The pyramidal configuration with wider base and narrower top provides adequate spacing for shorting prevention while maintaining a compact footprint for high memory density.
Solution Approach 2:
The patent changes the geometric parameters of the MTJ structure from a rectangular prism to a pyramidal shape, and adjusts the top electrode critical dimension to be smaller than the MTJ base dimensions. This parameter optimization allows sufficient spacing for reliability while minimizing the cell area for high density.
3Ease of manufacture
If conventional patterning processes are used, then manufacturing simplicity is maintained, but alignment accuracy between MTJ cell and conductive structure is reduced
Solution Approach 1:
The patent performs preliminary deposition of the top electrode with precise dimensional control before forming the MTJ structure. This preliminary action establishes a self-aligned reference that ensures accurate alignment between the MTJ cell and underlying conductive structures, eliminating the need for separate alignment steps.
Solution Approach 2:
The top electrode serves a dual function: as both the final functional component and as a self-aligned mask during MTJ formation. This self-service approach automatically ensures precise alignment without requiring additional alignment procedures, maintaining manufacturing simplicity while achieving high alignment accuracy.
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 approach increases memory density without lowering top electrode height, reduces shorting risks, and improves alignment accuracy between the MTJ cell and the conductive structure, while maintaining the integrity of the MTJ structure and top electrode.
Implementation Method 1
the MTJ structure and top electrode are formed using a bilayer dielectric material mask and physical vapor deposition
Data Source
AI summary
A memory structure including a magnetic tunnel junction (MTJ) structure and a top electrode that are both formed without utilizing ion beam etching is provided. The MTJ structure, which includes a lower magnetic stack, a tunnel barrier layer and an upper magnetic stack, is pyramidal shaped, and end portions of the lower magnetic stack of the MTJ structure are devoid of the tunnel barrier layer and the upper magnetic stack.