Self-Aligned Contacts on Pillar Structures for MRAM Scaling
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Solution Overview
Problem
Conventional semiconductor technologies face challenges in scaling MRAM devices due to surface topography issues, which limit contact density and size, particularly in spin transfer torque MRAM (STT-MRAM) where pillars are small, requiring larger contacts that hinder further miniaturization and density improvements.
Innovation Solution
The method involves forming self-aligned contacts on pillar structures using a spin-on material to create puddles between pillars, followed by selective etching of a protruding insulator to form contact trenches, eliminating the need for additional lithography steps and allowing for smaller contact sizes without misalignment, thereby improving contact density and device scaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithography alignment methods are used, then alignment precision can be maintained, but contact size must be larger to accommodate misalignment margins, reducing contact density
Solution Approach 1:
The spin-on material automatically forms puddles in the spaces between pillars through self-alignment during deposition, eliminating the need for separate alignment processes. This self-service mechanism enables precise contact formation without requiring large alignment margins, thereby increasing contact density while maintaining precision
Solution Approach 2:
The spin-on material is deposited and forms puddles between pillars before the contact etching process. This preliminary action defines the exact contact locations and sizes in advance, allowing subsequent etching to precisely follow these pre-defined boundaries without needing additional alignment margins
2Manufacturing precision
If additional lithography steps are added to improve alignment, then manufacturing precision improves, but process complexity and manufacturing cost increase
Solution Approach 1:
The formation of alignment features using spin-on material puddles is merged with the contact formation process itself. Instead of separate lithography and etching steps for alignment, the spin-on material deposition and puddle formation are combined into a single integrated process that simultaneously defines both alignment and contact geometry
Solution Approach 2:
The complex multi-step lithography alignment process is extracted and replaced by the simpler spin-on material puddle formation method. This extraction removes unnecessary process steps while retaining the essential alignment function, thereby reducing overall process complexity
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
This approach enables the formation of smaller, more densely packed contacts that align precisely with pillar structures, enhancing the scalability and density of MRAM devices without compromising existing wire processing, allowing for reduced power consumption and cost-effective higher density MRAM cell arrangements.
Implementation Method 1
forming two or more contacts to the two or more pillar structures, and forming an insulator between the two or more pillar structures and the two or more contacts, wherein the two or more contacts are self-aligned to the two or more pillar structures by forming the insulator via conformal deposition and etching the insulator selective to a spin-on material formed over the insulator between the two or more pillar structures
Data Source
AI summary
A semiconductor structure is disclosed herein. The semiconductor structure includes two or more pillar structures disposed over a top surface of a substrate. The semiconductor structure further includes two or more contacts to the two or more pillar structures. The semiconductor structure further includes an insulator disposed between the two or more pillar structures and the two or more contacts. The two or more contacts are self-aligned to the two or more pillar structures.