MRAM Cell Isolating Liner Prevents Etching Shunting
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Solution Overview
Problem
Conventional MRAM device manufacturing methods suffer from shunting issues due to sputtered material accumulation on magnetic layers during etching, which affects the integrity of the tunnel barrier layer.
Innovation Solution
A hard mask is applied to the magnetic stack, followed by a first etch to expose layers, and an isolating liner is deposited to protect the layers during a second etch, preventing shunting between the magnetic layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If photolithography is used to pattern the magnetic stack, then MRAM cells can be formed, but sputtered material accumulates on the magnetic stack causing shunting between layers
Solution Approach 1:
A liner layer is deposited on the magnetic stack before the patterning etch process. This preliminary action protects the magnetic layers from sputtered material accumulation during etching, preventing shunting between layers while allowing the photolithography process to proceed
Solution Approach 2:
The liner acts as an intermediary protective layer between the magnetic stack and the harmful sputtered material. It is deposited over the magnetic layers and removed after patterning, serving as a temporary shield that prevents direct contact between contaminants and the sensitive magnetic tunnel junction
2Manufacturing precision
If multiple etching steps are performed to form MRAM cells, then precise patterning is achieved, but chemical and physical damage occurs to the magnetic layers
Solution Approach 1:
The liner is deposited on the magnetic stack before the etching process begins. This preliminary protective action ensures that the magnetic layers are shielded from chemical and physical damage during the multiple etching steps required for precise MRAM cell patterning
Solution Approach 2:
The liner provides beforehand cushioning protection to the magnetic layers against the harmful effects of etching. By being in place before etching commences, it absorbs or prevents damage from reactive ions and sputtered material, allowing precise patterning without compromising layer integrity
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 isolating liner effectively prevents shunting between the magnetic layers, ensuring the integrity of the MRAM cell and protecting the layers from chemical and physical damage during the etching process.
Implementation Method 1
the liner prevents shunting between the protected magnetic layers
Implementation Method 2
magnetic tunnel junctions having a strong magnetoresistance at ambient temperatures
Data Source
AI summary
A manufacturing method to form a memory device includes forming a hard mask on a magnetic stack. A first magnetic stack etch is performed to form exposed magnetic layers. A liner is applied to the exposed magnetic layers to form protected magnetic layers. A second magnetic stack etch forms a magnetic random access memory (MRAM) cell, where the liner prevents shunting between the protected magnetic layers.