MTJ MRAM Contact Structure for Dense, Low-Power Memory
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Solution Overview
Problem
Current magnetic random access memory (MRAM) devices face challenges in achieving high storage density and low power consumption while maintaining fast access times and minimal degradation over time.
Innovation Solution
The development of an MRAM device based on a magnetic tunnel junction (MTJ) cell, which includes a semiconductor device structure with a specific film stack configuration and manufacturing process to optimize performance and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If magnetic tunnel junction (MTJ) cell structure is used, then storage density and power consumption are improved, but manufacturing complexity increases
Solution Approach 1:
The MTJ cell structure is divided into distinct functional layers including pinned magnetic layer, tunnel barrier layer, free magnetic layer, and cap layer. Each layer is formed through separate deposition processes with specific material compositions and thicknesses, allowing precise control of magnetic properties and tunneling characteristics while managing manufacturing complexity through modular fabrication
Solution Approach 2:
The patent employs composite magnetic layer structures with alternating ferromagnetic and non-magnetic metal layers (e.g., CoFeB/CoFe, CoFe/CoFeB) to achieve desired magnetic anisotropy and spin polarization. These composite structures enable high storage density through controlled magnetic coupling and exchange interactions between layers
2Speed
If thinner tunnel barrier layer is used, then access time is improved, but reliability deteriorates
Solution Approach 1:
The tunnel barrier layer thickness is precisely controlled within a narrow range (0.8-1.5 nm) to optimize the balance between electron tunneling probability and barrier integrity. The patent adjusts thickness parameters along with material composition (MgO-based) to achieve fast access times while preventing defect formation and maintaining reliable magnetic state retention
3Area of stationary object
If higher storage density is achieved, then device area is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent transitions from planar magnetic layer arrangements to vertically stacked MTJ structures with multiple thin films deposited in the thickness dimension. This vertical stacking enables higher storage density by utilizing the third dimension, while each layer's thickness is precisely controlled through advanced deposition techniques to maintain manufacturing feasibility
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 proposed MRAM device achieves comparable performance to SRAM, similar density to DRAM with lower power consumption, and faster access times than flash memory, while minimizing degradation over time.
Implementation Method 1
An MRAM cell is formed by a magnetic tunneling junction (MTJ) comprising two ferromagnetic layers which are separated by a thin insulating barrier, and operates by tunneling of electrons between the two ferromagnetic layers through the insulating barrier
Data Source
AI summary
In a method of manufacturing a semiconductor device, a magnetic random access memory (MRAM) cell structure is formed. The MRAM cell structure includes a bottom electrode, a magnetic tunnel junction (MTJ) stack and a top electrode. A first insulating cover layer is formed over the MRAM cell structure. A second insulating cover layer is formed over the first insulating cover layer. An interlayer dielectric (ILD) layer is formed. A contact opening in the ILD layer is formed, thereby exposing the second insulating cover layer. A part of the second insulating cover layer and a part of the first insulating cover layer are removed, thereby exposing the top electrode. A conductive layer is formed in the opening contacting the top electrode.