Magnetic Memory Device Bottom Electrode Planarization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional magnetic memory devices face challenges in high integration due to increased plane area of magnetic memory cells caused by misalignment during photolithographic processes, leading to degraded MTJ pattern characteristics and increased space between adjacent MTJ patterns.
Innovation Solution
The implementation of a magnetic memory device with bottom electrodes and planarized insulation layers, where MTJ patterns are connected to the bottom electrodes, and the insulation layer fills spaces between them, maintaining a consistent distance to prevent step differences and reduce the plane area of magnetic memory cells, thereby enabling high integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If misalignment margin regions are included in bottom electrodes and MTJ patterns to account for photolithographic misalignment, then manufacturing reliability is improved, but the plane area of magnetic memory cells increases
Solution Approach 1:
The patent introduces a vertical dimension by forming the bottom electrode as a three-dimensional structure that extends downward from the surface. This vertical extension allows the electrode to compensate for horizontal misalignment in the z-direction, enabling the top surface to maintain precise alignment with the MTJ pattern while the underlying structure provides tolerance for photolithographic variations.
Solution Approach 2:
The bottom electrode structure is designed to be nested within the magnetic memory cell structure, with the electrode extending downward into the substrate. This nesting allows the electrode to occupy vertical space rather than horizontal space, reducing the plane area requirement while maintaining alignment tolerance through the vertical extension.
2Reliability
If misalignment margin regions are included to prevent degradation from misalignment, then MTJ pattern characteristics are maintained, but the space between adjacent MTJ patterns increases
Solution Approach 1:
The bottom electrode utilizes the vertical dimension by extending downward into the substrate, which allows it to provide alignment tolerance without increasing the horizontal footprint. This vertical extension compensates for misalignment between the electrode and MTJ pattern while maintaining compact spacing between adjacent cells.
Solution Approach 2:
The bottom electrode structure exhibits different properties at different depths: the top surface maintains precise alignment quality to match the MTJ pattern, while the lower portions extend into the substrate to provide tolerance for photolithographic misalignment. This local differentiation of quality allows simultaneous achievement of precision and tolerance.
3Reliability
If the bottom electrode is connected to the contact plug and extends laterally to cover the digit line, then electrical connectivity is improved, but the plane area increases due to large electrode area
Solution Approach 1:
The bottom electrode transitions from a two-dimensional planar structure to a three-dimensional structure that extends vertically into the substrate. This vertical extension allows the electrode to maintain electrical connectivity with the contact plug and provide lateral coverage of the digit line while occupying minimal horizontal space, as the connectivity function is achieved through vertical rather than horizontal expansion.
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 configuration reduces the plane area of magnetic memory cells and allows for high integration by eliminating misalign margin areas, ensuring normal operation despite potential misalignment of MTJ patterns with bottom electrodes, and maintaining planarity to prevent degradation.
Implementation Method 1
Magnetic fields established by the bitline 13 and the digit line 3 change a magnetization direction of the second magnetic layer 10
Implementation Method 2
a magnetization direction of the first magnetic layer 8 is fixed, and a magnetization direction of the second layer 10 freely varies with external magnetic fields
Implementation Method 3
Resistance of the MTJ pattern varies with magnetization directions of the two ferromagnetic substances
Data Source
AI summary
A magnetic memory device includes bottom electrodes disposed on an interlayer dielectric on a substrate. The bottom electrodes are spaced apart from one another in one direction as much as a first distance. A planarized insulation layer fills spaces between the bottom electrodes and has a top surface coplanar with a top surface of the bottom electrode. Magnetic tunnel junction (MTJ) patterns are connected to the bottom electrodes, respectively, and are spaced apart from one another in the one direction as much as a second distance. The first distance is equal to the second distance.