MTJ Sidewall Oxidation After Ion Beam Etching to Prevent Shorts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic tunnel junction (MTJ) devices face issues with electrical shorts and adverse electrical characteristics due to the use of high-energy ion beam etching, which leads to the formation of poison layers and structural defects.
Innovation Solution
An oxidation process is employed to convert residual metal films on the sidewalls of MTJ structures into dielectric metal oxide layers, thereby removing electrical short paths and improving the electrical characteristics of the devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-energy ion beam etching is used to pattern MTJ structures, then manufacturing precision and etching capability are improved, but electrical shorts and adverse electrical characteristics occur due to poison layer formation
Solution Approach 1:
A protective capping layer is deposited over the MTJ structure before the ion beam etching process. This capping layer prevents direct ion beam damage to the magnetic layers, thereby avoiding poison layer formation and electrical shorts while still allowing precise patterning to occur
Solution Approach 2:
The capping layer acts as an intermediary between the ion beam etching process and the MTJ structure. It absorbs the harmful effects of high-energy ion bombardment while permitting the etching process to proceed with the required precision on the underlying layers
2Productivity
If high-energy ion beam etching is used to pattern MTJ structures, then etching speed and productivity are improved, but structural defects and poison layers are formed
Solution Approach 1:
The capping layer is deposited in advance to protect the MTJ structure during high-speed ion beam etching. This allows the use of higher ion beam energies and longer etching durations without causing structural defects or poison layers, thereby maintaining both productivity and structural integrity
Solution Approach 2:
The capping layer serves as a cushioning layer that absorbs the mechanical and chemical damage from high-energy ion bombardment. This protective barrier enables aggressive etching conditions to be used without compromising the structural integrity of the underlying MTJ layers
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 oxidation process effectively reduces bit error rates by 10-100 times, suppressing electrical shorts and enhancing the reliability of MTJ devices.
Implementation Method 1
An oxidation process is employed to convert residual metal films on the sidewalls of MTJ structures into dielectric metal oxide layers
Data Source
AI summary
A magnetic tunnel junction device includes a pillar structure including, from bottom to top, a bottom electrode and a magnetic tunnel junction structure, a top electrode overlying the magnetic tunnel junction structure, and a dielectric metal oxide layer extending from a sidewall of the pillar structure to a sidewall of the top electrode. The magnetic tunnel junction structure contains a reference magnetization layer including a first ferromagnetic material, a tunnel barrier layer, and a free magnetization layer including a second ferromagnetic material. The top electrode includes a metallic material containing a nonmagnetic metal element. The dielectric metal oxide layer may be formed by performing an oxidation process that oxidizes a residual metal film after a focused ion beam etch process, and eliminates conductive paths from surfaces of the pillar structure.