Amorphous Conductive Underlayer for Magnetoresistive Memory
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Solution Overview
Problem
Conventional magnetic memory devices lack an appropriate underlayer for magnetoresistive elements, which affects the quality and performance of the magnetoresistive elements, particularly in achieving excellent crystallinity, low sheet resistance, and preventing shunt failures.
Innovation Solution
A conductive underlayer with an amorphous structure containing elements like molybdenum (Mo), magnesium (Mg), rhenium (Re), tungsten (W), and vanadium (V) is used, along with additional elements like zirconium (Zr), tantalum (Ta), and niobium (Nb), to form a stacked structure with specific magnetic layers and a tunnel barrier layer, ensuring excellent crystallinity and low resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional underlayer is used for magnetoresistive elements, then the device structure is simple, but the crystallinity is poor and sheet resistance is high
Solution Approach 1:
The underlayer is constructed as a composite structure with a first underlayer containing CoFeB and a second underlayer containing CoFe, where each layer has specific thickness ranges (CoFeB: 1-5 nm, CoFe: 2-10 nm). This composite configuration enables both excellent crystallinity and low sheet resistance by combining the beneficial properties of different magnetic materials in a controlled multilayer structure.
Solution Approach 2:
The invention optimizes specific parameters including the thickness of each underlayer (CoFeB: 1-5 nm, CoFe: 2-10 nm), the composition ratios of magnetic layers (Co:Fe:B in specific ranges), and the magnetization directions (perpendicular or in-plane). These parameter optimizations achieve excellent crystallinity and low sheet resistance while preventing shunt failures.
2Reliability
If the underlayer composition is optimized for low sheet resistance, then resistance decreases, but shunt failures increase
Solution Approach 1:
The underlayer is divided into regions with different compositions and properties: the first underlayer (CoFeB) provides one set of properties while the second underlayer (CoFe) provides complementary properties. This local differentiation allows the structure to simultaneously achieve low sheet resistance in certain regions and high reliability/shunt failure prevention in other regions, resolving the contradiction between these two requirements.
Solution Approach 2:
By combining CoFeB and CoFe in a multilayer underlayer structure with controlled thicknesses and compositions, the invention creates a composite material system where the synergistic effects of the two materials achieve both low sheet resistance and high reliability, preventing shunt failures while maintaining energy efficiency.
3Reliability
If a simple underlayer structure is used, then manufacturing is easier, but magnetoresistive element performance is poor
Solution Approach 1:
The invention specifies precise parameter ranges for the underlayer structure (CoFeB thickness: 1-5 nm, CoFe thickness: 2-10 nm, composition ratios of Co:Fe:B) that can be achieved using conventional thin-film deposition techniques. By optimizing parameters within these ranges, excellent magnetoresistive element performance is obtained while remaining compatible with standard manufacturing processes.
Solution Approach 2:
The multilayer underlayer structure applies local quality differentiation where specific layers (CoFeB and CoFe) have tailored compositions and thicknesses to provide specific functions. This localized optimization enables high performance in critical regions while using simpler materials and processes in other regions, balancing manufacturing ease with element performance.
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 solution enables the formation of a magnetoresistive element with improved crystallinity, low sheet resistance, and prevention of shunt failures, ensuring proper operation and data storage capabilities.
Implementation Method 1
a conductive underlayer having an amorphous structure and containing at least one first predetermined element selected from molybdenum (Mo), magnesium (Mg), rhenium (Re), tungsten (W), vanadium (V), and manganese (Mn)
Implementation Method 2
magnetoresistive elements and MOS transistors are integrated on a semiconductor substrate
Data Source
AI summary
According to one embodiment, a magnetic memory device includes a conductive underlayer having an amorphous structure and containing at least one first predetermined element selected from molybdenum (Mo), magnesium (Mg), rhenium (Re), tungsten (W), vanadium (V), and manganese (Mn), and a stacked structure provided on the underlayer, and including a first magnetic layer having a variable magnetization direction, a second magnetic layer having a fixed magnetization direction, and a nonmagnetic layer provided between the first magnetic layer and the second magnetic layer.