Dual Metal Nitride Landing Pad for MRAM Uniformity
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Solution Overview
Problem
Conventional MRAM landing pads face issues with non-uniformity and surface roughness, leading to shorts or excessive dielectric recess, particularly between isolated wide pitch and dense narrow pitch MRAM devices, due to chemical mechanical polishing (CMP) inconsistencies.
Innovation Solution
A dual nitride landing pad is formed on a recessed surface of conductive structures in MRAM devices, comprising a bottom metal nitride landing pad and a TaN-containing landing pad, with a dielectric capping layer and a magnetic tunnel junction (MTJ) structure, ensuring uniformity and low surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical mechanical polishing (CMP) is used to create a damascene tantalum nitride (TaN) landing pad, then the landing pad can be formed, but non-uniformity and surface roughness occur leading to ground rule line-to-line shorts or excessive dielectric recess
Solution Approach 1:
The patent segments the landing pad into two distinct metal nitride layers: a bottom metal nitride layer and a TaN-containing landing pad layer. This segmentation allows each layer to be optimized independently - the bottom layer provides a uniform foundation while the TaN layer provides the necessary electrical and mechanical properties, thereby achieving both uniformity and reliability that cannot be obtained with a single-material landing pad
Solution Approach 2:
The patent employs composite materials by combining two different metal nitride materials (bottom metal nitride and TaN) in a layered structure. This composite approach leverages the complementary properties of each material - the bottom metal nitride provides excellent uniformity and adhesion, while the TaN layer provides appropriate electrical conductivity and mechanical strength, resolving the contradiction between uniformity and reliability
2Adaptability or versatility
If CMP is used for landing pad formation, then landing pads can be created, but non-uniformity occurs between isolated wide pitch MRAM devices and dense narrow pitch ground rule lines
Solution Approach 1:
By segmenting the landing pad into two layers with different materials, the patent enables independent optimization for different pitch configurations. The bottom metal nitride layer can be tuned for uniform deposition across all pitch types, while the TaN layer can be adjusted to provide appropriate properties for both isolated wide pitch devices and dense narrow pitch lines, achieving pitch adaptability without sacrificing uniformity
Solution Approach 2:
The segmented structure allows local quality optimization where each layer can have different thicknesses, compositions, and properties tailored to specific requirements. The bottom metal nitride layer provides a uniform base across all areas, while the TaN layer can be locally adjusted to accommodate different pitch requirements, enabling the structure to adapt to both isolated and dense configurations with maintained uniformity
Data Source
AI summary
A dual nitride landing pad for a high performance magnetoresistive random access memory (MRAM) device is formed on a recessed surface of the least one electrically conductive structure in a MRAM device area. The dual nitride landing pad includes a bottom metal nitride landing pad and a TaN-containing landing pad.