MRAM Seed Engineering With Sidewall Shunting for Lower Resistance
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Solution Overview
Problem
Conventional MRAM structures with thick tunnel barrier seed layers suffer from increased resistance, leading to a tunnel magnetoresistance (TMR) penalty, which adversely affects magnetic and crystallographic ordering in memory cells.
Innovation Solution
A memory structure with a seeding area including a tunnel barrier seed layer beneath a chemical templating layer, where redeposited metallic material shunts the sidewalls of the seed layer, reducing resistance while minimizing TMR loss, comprising a bottom electrode, non-magnetic pedestal, MTJ structure, and encapsulation layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a thick tunnel barrier seed layer is used, then deposition control is improved, but resistance increases causing TMR penalty
Solution Approach 1:
The structure is segmented into three distinct width zones: the MTJ structure with narrow width (W1), the chemical templating layer with intermediate width (W2), and the tunnel barrier seed layer with wide width (W3). This segmentation allows each zone to perform its specific function independently - the narrow MTJ maintains high TMR, while the wide seed layer provides excellent deposition control
Solution Approach 2:
The invention transitions from a two-dimensional planar structure to a three-dimensional stepped structure by varying the width of layers in the lateral dimension. The chemical templating layer extends laterally beyond the MTJ structure, creating an intermediate zone that facilitates controlled material deposition onto the wide seed layer without increasing the MTJ area
2Manufacturing precision
If a thick tunnel barrier seed layer is used, then deposition control is improved, but resistance increases
Solution Approach 1:
Different regions of the structure are assigned different widths to optimize local functions: the MTJ structure maintains narrow width for low resistance and high TMR, while the tunnel barrier seed layer uses wide width for excellent deposition control. The chemical templating layer provides an intermediate width zone that bridges these requirements
3Manufacturing precision
If the seeding area is wider than the MTJ structure, then deposition control is improved, but the TMR ratio decreases
Solution Approach 1:
The structure is divided into functional zones with different widths: the narrow MTJ structure (W1) preserves high TMR ratio, while the wider chemical templating layer (W2) and seed layer (W3) provide deposition control. The segmentation ensures that the wider seed layer does not directly contact the MTJ active region
Solution Approach 2:
The chemical templating layer serves as an intermediary structure between the narrow MTJ and the wide seed layer. It provides a controlled interface that allows material deposition from the wide seed layer to be transferred precisely to the narrow MTJ structure, preventing direct lateral extension that would degrade TMR
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 structure achieves reduced resistance with minimal TMR loss, enhancing magnetic and crystallographic ordering, thereby improving the performance of MRAM devices.
Implementation Method 1
redeposited metallic material is located on at least a sidewall of the tunnel barrier seed layer of the seeding area so as to shunt that area of the structure
Implementation Method 2
growing magnetic stacks on top of a relatively thick tunnel barrier seed layer is desired for better deposition control; a thin tunnel barrier seed layer results in magnetic or crystallographic disordering
Data Source
AI summary
A memory structure, i.e., magnetoresistive random access memory (MRAM) structure, is provided that includes a seeding area including at least a tunnel barrier seed layer located beneath a chemical templating layer that is wider than the magnetic tunnel junction (MTJ) structure that is located on the chemical templating layer. Redeposited metallic material is located on at least a sidewall of the tunnel barrier seed layer of the seeding area so as to shunt that area of the structure. The memory structure has reduced resistance with minimal tunnel magnetoresistance (TMR) loss penalty.